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REPORT 


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NICARAGUA  CANAL  COMMISSION 


1 897- 1 899 


REAR  ADMIRAL  JOHN  G.  WALKER,  U.  S.  N. 

PRESIDENT 

COLONEL  PETER  C.  MAINS,  U.  S.  A.         PROFESSOR  LEWIS  M.  HAUPT 

Corps  of  Engineers  Civil  Engineer 


^I^ANSPORTATION    LIBRARV 


WITH  AN  ATLAS 


^9e  £orb  (gattimovc  (preee 

The  Frihdenwald  Company 
BALTIMORE 

1899 


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CONTENTS 

PAGB 

■ 

Act  Authobizing  the  Appointment  of  the  Commission    XI 

Letter  of  Appointment  to  Members  of  the  Commission   XI 

Supplemental  Letter  of  Instructions XII 

Organization  of  the  Commission 1 

Letter  of  Instructions  to  the  Chief  Engineer   2 

Itinerary  of  the  Commission 3 

Physics  of  the  Canal  Region 5 

Lake  Nicaragua 5 

Western  Division 6 

Eastern  Division 7 

San  Juan  River 7 

Slopes  and  Distances 7 

Velocity  and  Discharge 8 

Lateral  Drainage 8 

Capacity  of  the  Channel 9 

Controlling  Section   9 

Computed  Velocities  and  Discharges 10 

Stability  of  Slopes 10 

Sanitary  and  Climatic 12 

Earthquakes  and  Volcanoes 13 

Materiaus  for  Structural  Purposes 13 

Alluvium    13 

Sand   13 

Clay 14 

Wood    14 

Iron  and  Steel 14 

Stone   15 

Classification  and  Weathering 16 

Dimensions  of  the  Canal 16 


yj  CONTENTS 

PAGE 

Regulation  of  the  Lake  Level 17 

Rainfall  18 

Evaporation  18 

Run-off , 19 

Lockage   1*9 

Limits  of  Regulation 19 

Location  of  Spillways 23 

Projects  and  Routes 24 

Western  Division 24 

Lake  Division 26 

Eastern  Division 26 

Gebytown  Harbob 29 

Brito  Harbor 31 

Dams  and  Embankments 32 

Dams  on  the  Eastern  Division 33 

Sites  for  Low  Dams .  34 

San  Carlos  and  San  Francisco  Embankment  Lines 34 

Dams  on  the  Western  Division 35 

Canal  Looks 35 

Quantities 36 

Unit  Prices 37 

Fbasibility   42 

Estimate    43 

Conclusions   45 

Appendix         I.  Report  of  the  Chief  Engineer 47 

n.  Geologic  Report 87 

m.  Hydrographic  Report * 193 

IV.  Report  of  J.  W.  G.  Walker,  Assistant  Engineer 343 

V.  Report  of  F.  L.  Stuart,  Assistant  Engineer 359 

VI.  Report  of  H.  H.  Trundle,  Assistant  Engineer 387 

Vn.  Report  of  Boyd  Ehle,  Assistant  Engineer 401 

Vm.  Report  of  S.  S.  Evans,  Assistant  Engineer 419 

LX.  Report  on  Precise  Levels * 431 

X.  Report  of  A.  Onderdonk,  Assistant  Engineer 475 

XI.  Report  of  L.  Hankins,  Assistant  Engineer 485 


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ILLUSTRATIONS 

Appendix  II. 

PAGE 

Plate.  I.  Map  of  the  San  Juan  Delta 98 

11.  Map  showing  changes  of  coast  lines  and  divides 102 

m.  Sections  showing  topographic  forms  in  the  San  Juan  Valley 104 

IV.  Volcano  Momotombo  from  Lake  Managua    110 

V.  The  Brito  formation  near  La  Flor    116 

VI.  Map  to  illustrate  recent  shifting  of  divides 142 

VII.  Map  of  Brito  harbor,  showing  depth  to  rock 1<)4 

Vni.  Drill  Sections,  Eastern  Divide 192 

IX.  Drill  Sections,  San  Francisco  Embankment 11)2 

X.  Drill  Sections,  Tambor  Grande  and  Tamborcito   192 

XL  Drill  Sections,  Lower  Ochoa  and  San  Carlos  Embankment 192 

XII.  Drill  Sections,  Upper  Ochoa 192 

XTTL  Drill  Sections,  Boca  San  Carlos •. 192 

XIV.  Drill  Sections,  Machuca,  Santa  Cruz  and  Conchuda 192 

XV.  Longitudinal  Sections  of  Eio  Grande  and  San  Juan  Valleys 192 

XVI.  General  Geologic  Sections 192 

XVn.  Geologic  Sections  at  dam  sites 192 

XVni.  Geologic  Sections  at  Embankment  lines 192 


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Appendix  III. 

Plate  I.  Gaging  Station  at  Brito 198 

n.  Lake  gage  at  Las  Lajas 202 

m.  Gaging  Rio  Viejo 204 

IV.  Gaging  Station  at  Tipitapa 208 

V.  Zapatero  and  Lake  Nicaragua 212 

VI.  Scene  on  San  Juan  River 218 

Vn.  Starting  to  Gage  a  River 227 

VHl.  Gaging  Rio  San  Carlos,  showing  use  of  staywire 233 

IX.  Rating  curves,  San  Juan  at  Ochoa   236 

X.  Comparative  Diagram,  San  Juan  and  San  Carlos 240 

XL  Rainfall  Diagram,  Brito — Deseado   262 


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yill  ILLUSTRATIONS 

PAGE 

Plate       XII.  Rainfall  Diagram,  Tipitapa — ^Rio  Viejo 2C6 

"         XIII.  Rainfall  Diagram,  Rio  San  Juan 274 

*'         XIV.  Rainfall  Diagram,  Las  Lajas — ^Ft.  San  Carlos — San  Francisco 276 

"  XV.  Monthly  Rainfall  at  Rivas,  1880-1898   278 

"         XVL  Daily  Rainfall  at  Rivas,  1890,  1807,  1898 280 

"        XVII.  Dam  site  at  Tipitapa  in  dry  season 292 

"  XVIII.  Elevation  of  Lake  Nicaragua  compared  with  syndironous  rainfall  in  its  basiin. 294 

"  XIX.  Inflow  to  Lake  Nicaragua,  compannl  with  accumulated  rainfall 296 

"  XX.  Measuring  the  sediment 301 

Figure  1.  Diagram  of  Daily  Discharge  of  Rio  (Jninde,  1898 200 

"       2.  Diagram  of  Daily  Discharge  of  Rio  Viejo,  1898    203 

"       3.  Diagram  of  Daily  Discharge  of  Rio  Tipitapa,  1898 211 

*^  4.  Diagram  of  Daily  Discharge  of  Tributaries  of  San  Juan  l)etwo(»n  Sahalos  and  Bo 

ca  San  Carlos,  1898 225 

"       5.  Diagram  of  Daily  Discharge  of  Rio  San  Jimn  above  Boca  San  ('arlos 220 

**       6.  Diagram  of  Daily  Discharge  of  Rio  San  Francisco  at  Embankment  line 248 

*'  7.  Comparative  monthly  rainfall  at  Greytown,  Ochoa,  Ft.  San  Carlos  and  Tola.  .  .  .278 

"       8.  Comparative  rainfall  at  Rivas  and  Masaya 297 

'*       9.  Sediment  Trap  ready  for  use 300 


CONTENTS  OF  ATLAS 

Map  No.  1 — In  4  sheets: 

Sheet  No.  1 — General  Map  of  the  Nicaragua  Canal  Region. 

Sheet  No.  2 — Geology  of  Canal  Region. 

Sheets  Nos.  3  and  4 — ^Hydrology  of  Canal  Region. 

Map  No.  2 — In  3  sheets,  showing  the  projected  lines  of  the  Nicaragua  Canal  on  the  scale  5000 

feet  to  1  inch. 

Map  No.  3 — In  20  sheets  and  Index  sheet,  showing  the  projected  lines  of  the  Nicaragua  Canal 

on  the  scale  of  1500  feet  to  1  inch. 

Map  No.  4 — Greytown  harbor. 

Map  No.  5 — Brito  harbor,  showing  Hydrography. 

Map  No.  6 — Hydrography  Caribbean  Coast  from  Indio  river  to  the  mouth  of  the  Colorado 

river. 

Map  No.  7 — Lake  Nicaragua. 

Profiles. 

Profile  No.  1 — In  2  sheets,  showing  Lull  route,  Variant  I,  East  Side. 

Profile  No.  2 — In  2  sheets,  showing  Menocal  route.  East  Side. 

Profile  No.  3 — Showing  Childs  route.  Variant  I,  West  Side. 

Profile  No.  4 — Showing  Childs  route,  Variant  11,  West  Side. 

Profile  No.  5 — Showing  proposed  railroad,  from  Greytown  to  Rio  Savalos. 

Profile  No.  6 — Showing  proposed  railroad,  from  Lake  Nicaragua  to  the  Pacific  ocean. 

Table  of  Quantities  for  various  Nicaragua  Canal  Routes. 
Plate  XlXa,  Diagram  of  Lake  Level  R^ulation. 


NICARAGUA  CANAL  COMMISSION 


To  continue  the  surveys  and  examinations 
authorized  by  the  Act  approved  March  second, 
eighteen  hundred  and  ninety-five,  entitled  "  An 
Act  making  appropriations  for  the  sundry  civil 
expenses  of  the  Government  for  the  fiscal  year 
ending  June  thirtieth,  eighteen  hundred  and 
ninety-six,  and  for  other  purposes,"  into  the 
proper  route,  the  feasibility  and  cost  of  construc- 
tion of  the  Nicaragua  Canal,  with  the  view  of 
making  complete  plans  for  the  entire  work  of 
construction  of  such  canal  as  therein  provided, 
one  hundred  and  fifty  thousand  dollars;  and  to 
carry  out  this  purpose  the  President  of  the 
United  States  is  authorized  to  appoint,  by  and 
with  the  advice  and  consent  of  the  Senate,  a 
commission  to  consist  of  one  engineer  from  the 
Corps  of  Engineers  of  the  United  States  Army, 
one  officer  of  the  Navy,  who  may  be  taken  from 
the  active  or  retired  lists,  and  one  engineer  from 
civil  life,  said  commis^^ion  to  have  all  the  i>owers 
and  duties  conferred  upon  the  commission  pro- 
vided for  in  said  Act. 

(Public  No.  2.  Approved  June  4,  1897. 
Page  54.) 

Department  of  State, 
Washington,  August  2,  1897. 
Gentlemen: — Pursuant  to*  that  portion  of  the 
Sundry  Civil  Appropriation  Act  (Public  No.  2) 
approved  June  4,  1897,  constituting  a  Nica- 
ragua Canal  Commission,  to  be  appointed  by 
the  President,  "  to  continue  the  surveys  and 
examinations  authorized  by  the  Act  approved 
March  2,  1895,  .  .  .  into  the  proper  route,  the 


feasibility  and  cost  of  construction  of  the  Nica- 
ragua Canal,  with  the  view  of  making  com- 
plete plans  for  the  entire  work  of  construction 
of  such  canal  as  therein  provided,"  you  have 
been  appointed  by  the  President  members  of 
said  Commission,  and  it  is  incumbent  upon  me, 
as  Acting  Secretary  of  State,  to  communicate 
to  you  the  following  instructions,  which  have 
been  approved  by  the  President,  for  the  guid- 
ance of  the  Commission: 

The  Commission  is  authorized  to  make  such 
journeys  and  to  do  such  work  as  may  be  neces- 
sary to  carry  into  effect  the  instructions  contain- 
ed in  the  Act.  To  facilitate  its  work,  the  Com- 
mission is  authorized  to  purchase  in  open  market 
such  materials,  including  instruments,  field  out- 
fit, supplies,  etc.,  as  in  its  judgment  are  neces- 
sary, and  to  employ  such  skilled  and  other  assist- 
ance as  it  may  deem  essential,  and  to  pay  such 
rates  of  compensation  as  may  be  deemed  proper. 
The  approval  of  the  President  of  the  Commission 
shall  be  final  authority  for  all  expenditures. 

An  itemized  account  of  all  disbursements, 
with  proper  vouchers,  will  be  submitted  through 
the  Department  of  State  for  audit  .  .  .  .' 

Respectfully  yours, 

Alvey  a.  Adee, 
Acting  Secretary^ 
Admiral  John  G.  Walker,  U.  S.  N., 

President, 
Captain  Obbrlin  M.  Carter, 

Corps  of  Engineers,  U.  S.  A. 
Prof.  Lewis  M.  Haupt, 

Civil  Engineer. 

Members  of  the  yicaraguu  Canal  Commission, 


ZII 


NICARAGUA  CANAL  COMMISSION 


Department  of  State, 

Washington,  November  3,  1897. 

Rear-Admiral  John  G.  Walker,  U.  S.  N., 
President;  Colonel  Peter  C.  Hains, 
Corps  of  Engineers,  TT.  S.  A.;  Professor 
Lewis  M.  Haupt,  Members  of  Nicaragua 
Canal  Commission,  Army  Building,  New 
York  City. 

Gentlemen: — Referring  to  the  Department's 
instructions  of  August  2,  1897,  concerning  the 
prosecution  of  the  work  of  the  Nicaragua  Canal 
(^mmission  agreeably  to  the  Act  of  Congress 
approved  June  4,  1897,  I  have  now  to  supple- 
ment those  instructions  in  the  following  par- 
ticulars. 

It  is  impossible  to  give  you  specific  instruc- 
tions for  the  execution  of  your  work  beyond 
referring  you  to  the  provisions  of  the  Act  re- 
ferred to  and  enjoining  upon  you  the  desira- 
bility and  the  necessity  of  prosecuting  your 
labors  to  completion  as  rapidly  as  circumstances 


will  permit.  It  will  be  observed,  by  reference 
to  the  Act,  that  it  contemplates  a  continuance 
of  the  previous  surveys,  "  with  a  view  of  making 
complete  plans  for  the  entire  work  of  construc- 
tion of  such  canal  as  therein  pro\'ided." 

The  Department's  understanding  of  this  lan- 
guage is  that  your  report  should  not  only  em- 
brace all  features  of  the  work  authorized  by  Con- 
gress under  the  present  law,  but  that  such  field 
notes  or  other  data  as  may  be  acquired  and  that 
may  be  necessary  for  the  complete  understand- 
ing of  the  President  and  Congress,  shall  be  spe- 
cifically included  in  your  report.  In  other 
words,  your  report  should  be  as  full  and  con- 
clusive upon  the  subject  as  it  is  practicable  to 
make  it,  to  the  end  that  "  the  proper  route,  the 
feasibility  and  cost  of  construction  of  the  Nica- 
ragua Canal "  may,  if  possible,   be  absolutely 

fixed  and  determined 

Respectfully  yours, 

John  Sherman. 


REPORT  OF  THE  NICARAGUA  CANAL 

COMMISSION. 


Washikgton,  D.  C,  May  9,  1899. 
The  President  of  the  United  States. 

Sir: — The  Nicaragua  Canal  Commission, 
having  completed  its  labors,  has  the  honor  to 
report  as  follows: 

The  Commission  was  organized  July  29,  1897, 
and  its  first  meeting  was  held  on  that  day.  It 
consisted  of  Rear-Admiral  John  G.  Walker, 
U.  S.  Navy,  President;  Captain  O.  M.  Carter, 
U.  S.  Corps  of  Engineers;  and  Professor  Lewis 
M.  Haupt,  Civil  Engineer,  members.  Captain 
Carter  was  relieved  from  duty  with  the  Com- 
mission and  was  succeeded  on  October  18  by 
Colonel  Peter  C.  Hains,  U.  S.  Corps  of  Engi- 
neers. 

This  Commission  has  imderstood  the  law,  ap- 
proved  June  4,  1897,  by  which  it  was  consti- 
tuted, to  require  that  all  routes  heretofore  pro- 
posed, having  any  merit,  should  be  considered, 
new  routes  that  appear  to  have  merit  should  be 
developed,  and  the  entire  region  of  canal  possi- 
bilities should  be  examined  with  sufficient  thor- 
oughness to  enable  a  just  and  comprehensive 
comparison  of  the  various  routes  to  be  made  and 
the  most  desirable  one  selected.  In  short,  to 
enable  it  to  make  a  complete  and  exhaustive 
report. 

With  this  in  view  the  Commission  established 

its  headquarters  in  the  Army  Building  in  New 

York  and  devoted  considerable  time  to  a  careful 
1 


examination  and  study  of  all  data  bearing  upon 
the  Nicaragua  Canal  question  obtainable  in  the 
United  States,  including  Government  surveys 
and  surveys  by  private  parties,  going  back  nearly 
fifty  years.  During  this  time  an  engineering 
staff  was  engaged,  and  the  organization  of  ex- 
ploring, surveying,  geological  and  hydrographic 
parties  was  proceeded  with,  considerable  delay 
being  caused  by  the  necessity  for  a  change  of 
Engineer  Members  of  the  Commission.  A 
Commissary  Department  was  also  organized  for 
the  handling  of  supplies  and  food  from  the 
United  States,  as  it  was  impossible  to  supply  the 
large  force  employed  with  promptness  -and  cer- 
tainty from  the  resources  of  Nicaragua  in  the 
wild  part  of  the  country  where  the  work  was 
prosecuted. 

The  preliminary  studies  having  been  made 
and  the  organization  completed,  the  expedition 
sailed  from  New  York  on  the  U.  S.  S.  "  New- 
port,"  on  December  5,  1897,  nearly  one  lum- 
dred  strong,  and  amved  off  Grey  town  Decem- 
ber 17.  The  men  and  stores  were  landed  as 
promptly  as  possible,  and  as  fast  as  laborers 
could  be  engaged,  the  various  parties  were  put 
into  the  field  and  entered  upon  the  work  as- 
signed them. 

Through  the  courtesy  of  the  Secretary  of  the 
Navy,  the  U.  S.  S.  '*  Newport ''  was  assigned 
to  the  service  of  the  Commission  for  the  survey 


2 


NICARAGUA   CANAL  COMMISSION 


of  Grevtown  harbor  and  vieinitv,  the  U.  S.  S. 
"  Alert  "  for  the  survey  of  Brito  and  its  vicinity, 
and  a  strong  hydrographic  party  under  Lieut. 
Hanus,  of  the  Xavy,  was  assigned  to  the  survey 
of  Lake  Nicaragua  and  the  San  Juan  river. 

The  following  instructions  for  the  guidance 
of  the  Chief  Engineer  of  the  Commission  were 
issued  December  21,  1897: 

San  Juan  del  Xorte,  Nicaragua, 

December  21,  1897. 
Mr.  E.  S.  \\"iieelek,  C.  E.,  Chief  Engineer  to 
the  Nicaragua   Canal  Commission. 

Sir: — The  Nicaragua  Canal  Commission,  ap- 
pointed by  the  President  under  the  Act  ap- 
proved Jime  4,  1807,  has  selected  you  to  take 
charge  of  the  field  work  and  direct  the  opera- 
tions of  the  various  parties  to  make  the  surveys 
and  examinations  provided  for  in  the  Act  above 
referred  to  in  reference  to  the  Nicaragua  Canal. 

The  scope  and  character  of  the  work  are  indi- 
cated by  the  words  of  the  law,  *^  to  continue  the 
surveys  and  examinations  .  .  .  into  the  proper 
route,  the  feasibility  and  cost  of  construction  of 
the  Nicaragua  Canal,  with  the  view  of  making 
complete  plans  for  the  entire  work  of  construc- 
tion of  said  canal  as  therein  provided." 

Your  familiarity  with  the  methods  employed 
in  conducting  surveys  and  examinations  under 
the  Government  with  a  view  to  projecting  works 
of  improvement  renders  it  unnecessary  at  this 
time  for  the  Commission  to  give  you  other  than 
general  instructions.  The  details  and  methods 
the  Commission  leaves  to  vou  to  work  out  as 
you  find  best  and  as  circumstances  render  ad- 
visable, the  field  parties  being  directly  under 
your  orders.  The  Commission  desires  as  a  final 
result,  to  be  in  possession  of  all  the  physical 
data  which  bear  in  any  important  way  upon  the 
construction  of  the  Nicaragua  Canal,  and  it  is 
expected  that  the  accuracy  and  trustworthiness 


of  these  results  shall  be  unquestioned.  Due 
care  will  Ix?  exercised  not  to  unnecessarily  dupli- 
cate anv  of  the  accurate  w^ork  alreadv  done. 

Naval  hydrographic  parties  working  under 
the  direction  of  the  Commission  will  survey 
Brito  harbor  and  vicinity,  Greytown  harbor  and 
vicinity,  Lake  Nicaragua  and  the  San  Juan  river. 
All  these  parties  will  connect  their  gages  w4th 
the  benches  established  by  your  topographical 
parties,  so  that  their  soimdings  and  your  work 
shall  confonn  to  the  same  datum  plane.  You 
are  expected  to  confer  freely  with  the  chiefs  of 
these  parties,  that  you  both  may  have  a  clear 
understanding  of  your  mutual  work. 

The  Commission  desires,  among  other  things, 
that  vou  determine  at  Grevtown  and  Brito  the 
mean  sea  levels  and  connect  them,  if  practicable, 
with  a  line  of  precise  levels  from  ocean  to  ocean. 

You  will  also  make  such  survevs  between  Brito 

t-' 

and  Lake  Nicaragua  as  may  be  necessary  to 
locate  the  best  line  for  the  canal,  and  such  other 
investigations  as  may  serve  to  determine  the 
practicability  of  controlling  the  lake  level  by  a 
weir  on  the  west  side. 

Borings  should  be  made  to  ascertain  the  kind 
and  quantity  of  material  to  be  removed  in  form- 
ing the  harbor  at  each  terminus  of  the  canal  and 
along  its  entire  route,  including  the  San  Juan 
river.  These  borings  should  be  made  more 
numerous  at  the  proposed  site  of  locks,  sluices 
and  dams  than  are  necessarv  elsewhere.  Par- 
ticular  attention  should  be  given  to  the  Ochoa 
and  other  important  dams  and  to  the  San  Fran- 
cisco and  San  Carlos  embankment  lines.  The 
feasibility  of  the  Canal  Company's  project 
hinges  on  the  control  of  the  lake  level,  the  Ochoa 
dam  and  the  maintenance  of  the  Divide  cut. 
All  possible  data  bearing  on  these  questions 
should  be  gathered. 

The   proper   Naval   hydrographic   party   will 


REPORT   OF  THE  COMMISSION 


make  the  necessary  survey  of  Lake  IXicaragua 
to  determine  with  sufficient  accuracy  its  area, 
in  order  that  the  question  of  controlling  its  level 
may  be  properly  studied,  the  extent  of  the  avail- 
able anchorage  between  Ometepe  island  and 
the  west  shore  be  ascertained,  as  well  as  the 
safety  of  the  course  which  would  be  followed  by 
steamers  between  the  western  entrance  to  the 
canal  and  the  head  of  the  San  Juan  river. 

AVhere  the  bends  of  the  river  are  sharp  it 
may  be  necessary  to  cut  through  them.  The 
survey  should  be  made  to  cover  such  possible 
contingency.  The  disposal  of  the  spoils  from 
the  excavations  in  the  river  must  be  taken  into 
consideration.  These  should  be  deposited  where 
thev  will  facilitate  rather  than  interfere  with 
navigation. 

A  suitable  number  of  rain  and  evaporation 
stations  should  be  established  at  the  most  de- 
sirable points  in  the  drainage  basin  affecting  the 
canal.  The  records  of  these  should  be  continued 
as  long  as  practicable. 

The  low-level  line  following  the  San  Juan 
to  near  its  junction  with  the  Colorado  should 
also  be  surveved,  and  an  estimate  of  its  cost  de- 
termined  for  comparison  with  other  projects. 
This  lipe  has  always  been  regarded  as  practica- 
ble, and  while  it  has  considerably  greater  length 
than  the  comparatively  direct  line  through  the 
Divide,  it  will  avoid  some  of  the  difficult  engi- 
neering problems  of  the  latter  route. 

The  survev  of  the  San  Juan  should  also  in- 
elude  the  gaging  of  the  river  at  numerous 
points,  the  determination  of  its  slope  in  high  and 
low  stages,  its  discharge  in  both  stages,  the  dis- 
charge and  regimen  of  the  principal  streams  that 
empty  into  it  and  generally  all  information  nec- 
essary to  determine?  the  best  method  of  improv- 
ing its  navigation,  whether  by  canalization  or 
otherwise. 


All  the  field  parties  will  receive  their  instruc- 
tions directly  from  you.  It  is  expected,  how- 
ever, that  you  will  keep  the  Commission  fully 
infonned  as  to  the  character  of  the  work  being 
done  and  the  methods  adopted  by  you  in  doing 
it.  For  this  purpose  you  will  submit  monthly 
reports  to  the  Commission  (which  shall  contain 
a  concise  history  of  the  operations  and  progress 
of  the  work),  and  such  special  reports  as  may 
from  time  to  time  be  necessary.  These  instnic- 
tions  are  not  intended  to  be  final  and  complete, 
but  may  be  supplemented  by  others  from  time 
to  time  as  the  exigencies  of  the  work  demand. 
I  am,  very  respectfully, 

J.  G.  Walker, 
President  of  the  Commission. 

The  Commission  remained  in  Grevtown  until 
January  8,  1898,  when  it  proceeded  in  a  special 
steamer,  kindly  placed  at  its  disposal  by  the 
Kicaraguan  Government,  to  the  examination  of 
the  San  Juan  river  from  the  sea  to  where  it 
leaves  Lake  Nicaragua,  including  the  Colorado 
branch. 

Five  days  were  occupied  in  this  examination. 
The  Commission,  arriving  at  Fort  San  Carlos, 
the  head  of  the  San  Juan  river,  on  the  evening 
of  January  13,  proceeded  at  once  by  steamer 
to  San  Jorge,  where  it  arrived  on  the  following 
morning,  and  after  putting  ashore  its  equipment, 
supplies  and  extra  baggage,  continued  to  Gra- 
nada and  Managua  for  the  purpose  of  paying  its 
respects  to  the  President  of  the  Republic. 

Arriving  at  Managua  on  the  afternoon  of  the 
15th  of  January  the  Commission  was  specially 
received  by  the  President  at  8  o'clock,  on  the 
same  evening,  w^th  all  the  ceremonies  and 
honors  pertaining  to  such  occasions.  During 
its  stay  in  Managua  every  attention  w^as  shown 
by  the  President,  members  of  the  Cabinet  and 


NICARAGUA   CANAL  COMMISSION 


other  ofRcers  of  the  Government.  On  the  morn- 
ing of  the  18th,  the  Commission  called  upon  the 
President  to  take  formal  leave  and  then  pro- 
ceeded by  rail  to  Granada,  was  transferred  to 
the  lake  steamer  "  Victoria,"  and  reached  San 
Jorge  late  the  same  afternoon,  arriving  at  Kivas 
shortly  aftenvards,  where  temporary  headquar- 
ters were  established. 

Promptly  upon  its  arrival  at  Rivas  the  Com- 
mission took  up  the  investigation  of  the  canal 
route  from  the  lake  to  the  Pacific,  and  remained, 
either  in  Rivas  or  upon  the  proposed  line  of  the 
canal,  until  February  13,  having  been  some- 
what delaved  bv  an  attempt  at  a  revolution  dur- 
ing  that  period. 

On  the  13th  the  Commission  left  by  steamer 
for  San  Carlos,  at  the  head  of  the  river  San 
Juan,  arriving  at  that  point  on  the  morning  of 
the  14th. 

After  inspecting  the  work  of  the  parties  under 
Lieutenant  Hanus,  U.  S.  N.,  and  Mr.  Stuart, 
Assistant  Engineer,  the  Commission,  on  the  fol- 
lowing morning,  proceeded  down  the  river,  land- 
ing that  afternoon  at  Ochoa,  and,  after  exam- 
ining the  work  going  on  in  that  neighborhood, 
which  included  borings  at  the  proposed  site  of 
the  Ochoa  dam,  started  on  foot  upon  the  trail 
over  the  Divide,  for  a  personal  examination  of 
that  part  of  the  line,  arriving  at  Greytown  at 
C  P.  M.  on  the  21st. 

The  Commission  remained  in  Greytown  imtil 
February  27,  when  it  left  on  board  the  IT.  S.  S. 
"  ^Newport "  for  Port  Limon,  Costa  Rica,  arriv- 
ing there  on  the  following  day,  and  proceeding 
by  special  train,  provided  by  order  of  the  (^osta 
Rican  Goveniment,  to  the  capital  (San  Jose), 
for  the  purpose  of  paying  its  respects  to  tlie 
President  of  Costa  Rica.  Thc^  Commission  was 
pleasantly  received  by  the  President,  by  special 
appointment,  at  8  P.  M.,  March  1.     The  next 


day  was  spent  in  visiting  the  neighborhood  of 
the  capital,  leaving  San  Jose  by  special  train  on 
the  morning  of  the  3d  for  Port  Limon,  and  go- 
ing immediately  on  board  the  "  Xewport.^' 
During  the  trip  to  and  from  San  Jose  the  cuts 
and  embankments  along  the  line  of  railroad 
were  carefully  observed  with  a  view^  to  obtaining 
information  w^itli  regard  to  the  stability  of  slopes 
in  tropical  regions  in  connection  with  the  pro- 
posed canal. 

The  "  Newport  ••  sailed  at  0  P.  M.,  March  3, 
for  Colon,  arriving  the  following  day  (^larch  4). 
The  five  succeeding  days  were  spent  in  exam- 
ining the  Panama  Canal  line,  the  work  being 
done,  and  the  plans,  drawings  and  data  in  the 
oflice  of  the  company  in  Panama. 

In  this  connection  the  Commission  wishes  to 
express  its  warmest  thanks  to  Monsieur  Belin, 
the  Director-General,  and  to  the  officers  of  his 
staff,  for  their  kindness  and  untiring  efforts  to 
facilitate  its  work  in  every  way  possible,  also  to 
Mr.  John  F.  Shaler,  the  Superintendent  of  the 
Panama  Railroad,  for  his  aid,  assistance,  personal 
efforts  and  care  during  its  entire  stay  upon  the 
Isthmus. 

On  the  10th,  having  taken  leave  of  the  offi- 
cials at  Colon,  the  "  Xewport ''  sailed  for  Port 
Limon  and  Greytown,  arriving  at  Greytown  on 
March  12. 

On  March  20  the  Commission,  having  com- 
pleted its  personal  examination  of  the  proposed 
Nicaragua  Canal  Route,  took  its  departure  for 
the  United  States,  leaving  its  working  parties  in 
the  field  to  prosecute  the  work  assigned  them 
under  the  direction  of  Mr.  E.  S.  Wheeler,  its 
Chief  Engineer. 

Much  delay  to  the  work  and  great  annoyance 
to  working  parties  were  caused  by  attempts  at 
revolution  and  bv  the  strained  relations  between 
the  Governments  of  Nicaragua  and  Costa  Rica, 


REPORT   OF   THE   COMMISSION 


which  rendered  it  difficult  and  often  impossible 
to  forward  supplies,  provisions  and  orders  to 
working  parties  in  the  field  and  to  receive  re- 
ports from  them.  It  is  a  difficult  country  in 
w^hich  to  carry  on  work  of  the  kind  assigned  to 
this  Commission  at  any  time,  but  the  difficulties 
were  increased  many  fold,  and  great  delay  was 
caused  bv  the  disturbed  conditions  referred  to. 
The  outbreak  of  the  war  between  the  Ignited 
States  and  Spain  w^as,  also,  a  serious  matter.  It 
deprived  the  Commission  of  two  ships  and  the 
naval  parties  which  were  working  with  and 
under  its  direction,  rendering  a  new  organiza- 
tion of  parties  necessary  and  with  a  much  de- 
creased force. 

Further  delay  was  caused  by  the  assignment 
of  Colonel  Hains  to  militarv  duty  in  command 
of  troops  at  Chickamauga,  and  later,  in  Porto 
Kico. 

But  in  vspite  of  these  troubles  and  delays  the 
work  w^as  prosecuted  as  rapidly  as  practicable. 

As  portions  of  the  work  were  completed, 
parties  were  withdrawn,  until  the  last  surveying 
party  left  Greyto^vn,  February  18,  1899,  leav- 
ing 13  men  in  the  country  at  10  stations  for  the 
purpose  of  continuing  the  observations  for  rain- 
fall and  evaiK)ration,  and  for  the  gaging  of  the 
lake  and  the  various  rivers  necessary  to  a  com- 
plete understanding  of  the  hydrology  of  the 
region  of  the  country  through  which  a  canal 
across  Nicaragua  must  pass. 

Soon  after  the  (/Ommission's  arrival  home,  the 
necessities  of  the  war  forced  it  to  vacate  its  head- 
quarters in  the  Army  Building  in  Xew  York, 
and  they  were  removed  to  Washington,  where 
the  work  of  examining,  computing  and  assem- 
bling the  data  has  been  steadily  prosecuted. 

The  Commission  desires  to  express  its  obliga- 
tions to  the  Maritime  Canal  Company,  which 
kindly  and  freely  furnished  all  data  and  infor- 
mation in  its  possession; 


To  the  Navy  Department,  for  assistance  with 
ships,  parties  and  instruments; 

To  Commanders  Tillev  and  I^utze,  command- 
ing  the  U.  S.  S.  ''  Newport,"  and  the  U.  S.  S. 
"  Alert,"  for  their  excellent  surv^eys  of  Grey- 
town  and  Brito; 

To  the  Director  of  the  Geological  Sun^ey  for 
the  services  of  C.  W.  Hayes,  Geologist,  and  A, 
P.  Davis,  Hydrographer; 

To  the  Chief  of  Engineers  and  to  the  Super^ 

intendent  of  the  Coast  Sun-ev  for  instruments 

«. 

kindly  loaned; 

To  the  Panama  Canal  Company  and  the 
Panama  Railroad  for  aid  and  courtesies  ren- 
dered ; 

To  E.  S.  Wheeler,  C.  E.,  Chief  Engineer  to 
the  Commission,  and  to  the  members  of  the  en- 
gineering staff  for  their  faithful  services  in  con- 
nection with  the  w^ork. 

Physics. 

To  secure  the  Ix^st  location  for  the  canal  care- 
ful attention  must  be  given  to  the  physical  fea- 
tures of  the  isthnms  and  their  adaptation  to  the 
purpose. 

As  the  repoi-ts  of  the  specialists,  hereto  an- 
nexed, cover  the  subjects  of  geology,  topog- 
raphy, hydrology  and  meteorology  quite  fully, 
it  would  seem  unnecessary  to  do  more  than  call 
attention  to  a  few  distinct  features  which  char- 
acterize the  route  on  which  this  (/'ommission  is 
directed  to  report. 

Lake  Nicaragua. 

It  is  an  interesting  and  peculiar  feature  of  this 
route  that  in  early  geologic  time  the  lake  was 
evident Iv  an  arm  or  bav  of  the  Pacific  ocean, 
while  the  Continental  Divide  traversed  the 
isthmus  to  the  eastward  in  the  vicinity  of  Cas- 
tillo  Viejo,  and  the  Rio  San  Juan,  as  an  outlet 
of  the  lake,  had  no  existence.     This  is  attested 


NICARAGUA  CANAL  COMMISSION 


by  the  remains  of  an  old  river  channel  of  large 
dimensions  which  crossed  the  Western  Divide 
and  formed  the  outlet  of  the  lake  after  it  be- 
came separated  from  the  ocean,  and  by  other 
geologic  features. 

An  old  drainage  channel  is  also  traceable 
under  the  Eio  San  Juan  west  of  C^istillo,  which 
has  gradually  filled  up  with  alluvium  to  the 
present  bed  of  the  stream.  There  is,  therefore, 
but  little  rock  found  in  this  portion  of  the  river. 

In  consequence  of  the  closure  of  the  western 
outlet  and  the  elevation  of  the  lake  to  a  mean 
altitude  of  over  one  hundred  feet  above  the  sea, 
the  outflow  was  diverted  to  the  eastward  over  a 
depression  in  the  original  divide,  so  that  this 
river  now  forms  the  only  outlet  for  tlie  drainage 
of  the  entire  basin. 

The  physical  elements  which  are  of  most  im- 
portance in  the  consideration  of  the  problem  of 
water  supply,  lake  regulation,  storage  and  oper- 
ation, have  been  ascertained  by  obser\"ation,  sur- 
veys and  measurements  as  far  as  possible  and 
mav  be  stated  as  follows: 


convenient  for  anchorage.  Xear  the  outlet  of 
the  lake  it  shoals  to  such  an  extent  as  to  require 
a  considerable  amount  of  dredging  through  soft 
material.  Xo  rock  is  found  near  this  portion  of 
the  channel.  The  area  of  that  portion  of  the 
lake  extending  below  sea  level  is  about  20  square 
miles.     A  steady  northeast  trade  sweeps  over  the 

lake  during  a  large  portion  of  the  year. 

• 

Western  Division. 

The  lake  is  separated  from  the  Pacific  on  the 
west  by  a  strip  of  land  about  12  miles  wide  with 
a  range  of  hills  having  heights  varv'ing  from  155 
feet  to  more  than  a  mile  above  sea  level.  The 
lowest  point  has  been  selected  for  the  route  of 
the  canal,  and  is  where  a  low  plateau  sei)arates 
the  drainage  of  the  Rio  Lajas,  which  empties 
into  the  lake,  from  the  Rio  Grande,  emptying 
into  the  Pacific  near  Brito  head.  This  latter  is 
a  bold,  rocky  promontory  248  feet  high,  which 
guards  a  natural  bight  in  the  coast  and  affords 
an  admirable  site  for  an  artificial  entrance  and 
harbor. 


Area  of  water  surface  of  Lake  Nicaragua 2,000,000  acres,         3,000  sq.  miles. 

Approximate  area  of  entire  drainage  basin 12,900  sq.  miles. 

Maximum  dimensions  of  Lake  Nicaragua 101  x  45  miles. 

Elevation  of  Lake  Nicaragua,  98'  to  111',  mean  104^'  above  mean  sea  level. 

Elevation  of  Lake  Managua  (above  Lake  Nicaragua)  approximately 28  feet. 

Area  of  Lake  Managua 438  sq.  miles. 

Length  of  Rio  San  Juan 121.7  miles. 

Extreme  range  of  temperature  on  line  of  canal  for  1898  (G5°  to  9C^).  . .  .31  degrees. 

Maximum  rainfall  observed  at  Rivas  was  in  1897,  when  it  was 123.43  inches. 

Minimum  rainfall  observed  at  Rivas  was  in  1890 31.81  inches. 

The  average  rainfall  in  the  basin  for  1898  is  found  to  be  28  per  cent,  less  than  that 
at  Rivas. 


The  lake  is  elliptical  in  form  and  has  several 
islands.  The  principal  one,  containing  the  sym- 
metrical cones  of  the  extinct  volcanoes  Ometepe 
and  Madera,  rises  over  a  mile  above  the  lake 
level  and  affords  an  excellent  harbor  to  leeward. 


The  streams  of  this  section  are  small  and  have 
a  limited  drainage,  being  nearly  drv  for  five 
months  of  the  year.  The  sIojk?  of  the  upper 
Rio  Grande,  however,  is  steep  and  its  bed  is 
therefore  sinuous  and  deeply  eroded.     Between 


REPORT   OF   THE   COMMISSION 


Espinal  and  the  sea,  a  distance  of  less  than  11 
miles,  it  falls  about  120  feet.  The  topography 
of  the  valley  is,  however,  well  adapted  to  the 
purposes  of  a  canal  on  either  bank,  or  to  the 
creation  of  an  artificial  basin  by  a  dam  closing 
the  gorge  through  which  the  lake  drainage  for- 
merly passed  to  the  sea.  The  rocks  on  this  di\d- 
sion  are  sedimentarv'^  and  readily  worked,  being 
loose  shales  and  sandstones  with  traces  of  cal- 
cium. The  material  composing  the  coastal  plain 
is  a  light  sandy  loam  and  easily  eroded. 

Eastern  Division. 

The  country  traversed  by  the  San  Juan  may 
be  conveniently  divided  into  two  sections,  to 
wit :  that  portion  lying  above  the  confluence  with 
the  San  Carlos,  in  which  the  deposit  of  sediment 
is  relatively  small,  and  that  below,  in  which  it 
is  large.  Further  subdivisions  are  suggested  by 
the  topographic  conditions.  From  the  lake  to 
the  first  rapids  at  Toro,  27  miles,  the  slope  is 
gentle,  being  about  2^  inches  per  mile,  while  the 
banks  are  low  and  the  adjacent  swamps  exten- 
sive. From  the  head  of  the  Toro  to  the  foot  of 
the  Machuca,  embracing  the  four  rapids,  the  fall 
is  nearly  43  feet  in  23  miles,  or  22i  inches  per 
mile.  This  comprises  the  rocky  section  of  the 
ancient  Continental  Divide  and  is  the  gorge  of 
the  river  valley.  Below  Machuca  occurs  a 
stretch  of  about  15  miles  of  deep  water,  the  bot- 
tom of  which  extends  in  places  to  below  sea  level, 
known  as  the  Agua  Muerta  (dead  water).  This 
is  a  portion  of  the  old  river  channel  not  silted  up 
by  the  volcanic  sands  brought  into  the  lower  San 
Juan  by  the  San  Carlos  river.  This  sand  be- 
comes a  characteristic  feature  of  the  entire  lower 
reach  of  the  river  and  its  delta,  from  this  point 
to  the  sea.  It  is  confined,  however,  mainly  to 
the  bed  of  the  channel,  the  banks  through  the 
hill  country  being  the  stiff  clays  resulting  from 


the  weathering  of  the  rocks  of  the  region.  These 
banks  are  remarkably  stable,  notwitlistanding 
the  heavy  rains  and  large  volume  of  water  which 
sweep  past  their  bases  at  high  stages. 

Physics  of  the  Stream. 

As  the  bed  of  the  upper  river  forms  an  im- 
portant part  of  the  route,  a  more  detailed  descrip- 
tion of  it  is  believed  to  be  necessarv. 

The  slope  as  given  by  the  survey  and  corrected 
for  stage  may  be  stated  to  best  advantage  in 
tabular  form.  This,  taken  with  the  cross  sec- 
tions, velocity  and  volume  of  discharge  as  stated 
in  detail  in  the  accompanying  reports  of  the  as- 
sistants, will  show  the  characteristics  of  the 
streams  in  a  state  of  nature. 

San  Juan  Kfver  Statistics. 

Slopes  and  Distances. — Upper  River. 

(Lake  at  105.) 

Rate  of  fall 
M^o^u  Distance,     Fall,    per  mile, 

Keacn.  miles.        feet.        feet. 

From  the  lake  to  Sabalos. 27.16       5.4       0.198 

Sabalos  to  foot  of  Toro 

rapids 1.70       7.8       4.294 

Toro  to  head  of  Castillo. .   7.98       1.2       0.150 

Castillo  to  bottom  of  rapids     .38       6.0     15.789 

Bottom  of  Castillo  rapids 

toPuntaGorda 2.08       2.5       1.202 

Punta  Gorda  to  1  mile  be- 
low Machuca  rapids.  .  .10.62     26.0       2.448 

One  mile  below  Machuca 
rapids  to  Boca  San  Car- 
los   ..14.79       1.0       0.067 

Upper  river 64.71     49.4       0.763 

IX)WER    Rn^ER. 

Rate  of  fall 
M^nnv^  Distance,     Fall,    per  mile, 

Keach.  m\\Q%.         feet.        feet. 

Boca   San   Carlos  to   San 

Juanillo 33.02     30.0       0.908 

San  Juanillo  to  Colorado.  5.28  4.0  0.757 
Colorado  to  ^!ea   (via   San 

Juan) 18.65     21.0       1.12^ 

Lake  to  sea 121. 6()  104.4       0.86 


8 


NICARAGUA   CANAL  COMMISSION 


The  slopes  are,  however,  constantly  varying 
witli  the  stage  and  local  conditions.  In  fact  a 
heavv  rainfall  on  the  San  Carlos  basin  niav  re- 
verse  the  slope  for  a  time  in  the  Agua  !^^uertx^ 
causing  the  water  to  run  up  stream. 

At  Sahalos,  where  the  slojw  is  about  2^  inches 
per  mile,  the  maximum  velocities  and  discharges 
as  observed  were  reported  as  follows: 

Cro88  section,    Mean  vclority,    Diwhargo, 
sq.  tt.  ft.  iH»r  nev.    cu.  ft.  per  sec. 


Date. 

Jan.  21, '98..  8,819 

Feb.  21,  '98  .  8,570 

Sept.  11,  -98.  11,273 

''      1-1,  '98.  10,684 

"   21,  '98.  10,720 

Dec.  3,  '98  . .  11,273 


2.10 
1.92 
1.95 
2.12 
2.09 
2.39 


19,000 
16,530 
21,995 
22,673 
22,431 
26,700 


In  the  up]>er  reaches,  the  slo]>e  being  verv^ 
flat,  the  river  carried  over  20,000  cubic  feet 
through  sections  of  over  10,000  square  feet  at 
velocities  exceeding  2  feet  per  second,  with  cor- 
responding increase  at  the  gorges  and  rapids. 

Observkd  ^Iaximum  Vfxocities  of  San  Juan. 

At  Ochoa  station,  about  69  miles  from  the 
lake,  the  banks  are  steep  clay  slopes.  The  bed 
of  the  river  consists  of  black  sand  of  the  same 
character  as  that  comjiosing  the  sea  Iwach  near 
Grevtow^n. 

i\u*n  Cross  section.    Mean  velocity,     Dischartfe, 

iiait.  sq.ft.  ft.  per  sec.      cu.  ft  per  sec. 

Jan.  8, '98...  13,100 

June  28,  '98.  14,462 

Nov.  17,  '98.  19,717 

Sept.  12,  '98.  10,336 

''      16,  '98.  12,761 

"  2ij,   '98.  9,895 

From  which  it  appears  that  in  a  state  of  na- 
ture the  mean  velocity  of  the  stream  is  fre- 
quently over  4  feet  ix?r  second  and  at  times  ex- 
ceeding 5,  while  the  lower  river  disc*harges  over 
50,000  cubic  feet  per  second  and  occasionally 


4.00 

52,400 

4.25 

61,410 

5.32 

104,930 

4.00 

41,199 

4.47 

57,047 

4.24 

41,975 

over  100,000  without  i>erceptible  effect  upon  the 
banks. 

The  slopes  of  the  stream,  therefore,  vary  from 
about  one  inch  per  mile  in  the  Agua  Muerta  to 
6  feet  in  one-third  of  a  mile  on  the  rapids  at  Cas- 
tillo, and  the  velocitv  from  less  than  one  foot 
per  second  to  over  12,  while  the  recorded  dis- 
charge at  Ochoa  ranges  from  16,145  to  104,930 
cubic  feet  })er  second.  To  pass  the  Castillo  rap- 
ids at  low  stages  of  the  river  a  tram-way  has 
been  constructed  under  the  brow  of  the  hill 
for  the  j)urix)se  of  transferring  passengers  and 
freight.  The  width  of  the  upper  river  is  quite 
variable.  Its  narrowest  limits  are  about  350 
feet,  while  in  some  places  it  wi<lens  out  to  1200 
feet.  Its  general  alignment  is  direct,  but  there 
are  several  shaq:)  horseshoe  cun'es  where  cut- 
offs would  be  required  across  alluvial  flats  by 
which  over  4  miles  of  distance  would  be  saved. 

The  Lateral  Dkainaoe. 

The  principal  tributaries  from  the  Costa  Rican 
side  are  the  Rio  Frio,  P(h*(>  Sol,  San  Carlos  and 
Sarapiqui,  the  former  emj)tying  into  the  lake 
just  at  the  head  of  the  river.  These  large 
streams  exert  a  controlling  influence  in  confin- 
ing the  location  of  the  canal  to  the  left  bank. 
The  streams  on  th(*  left  bank  are  the  Melchora, 
Palo  de  Arco,  Negro,  Sabalos,  Machuca,  La 
Cruz,  Alachado,  Danta,  San  Francisco  and  oth- 
ers, none  of  which  have  a  large  drainage  basin. 
They  have  many  small  branches  penneating  the 
swanqw  and  ravines  which  characterize  the 
brok(Mi  topography  of  this  section. 

On  reaching  the  edge  of  the  coastal  ]>lain  the 
river  drainage  is  distribute<l  through  the  San 
Juanillo,  Colorado,  lower  San  Juan,  Taura  and 
their  branches,  Parado  and  Cafio  linivo,  leading 
to  the  sea. 

The    minimum    computed    discharge    of    the 


REPORT   OF  THE  COMMISSION 


upper  river  at  the  Sabalos  station  during  1898 
was  found  to  be  11,206  cubic  feet  per  second  on 
May  13,  while  the  maximum  occurred  on  jS'o- 
vember  13,  when  it  was  28,490  feet,  the  differ- 
ence in  stage  being  3.55  feet.  At  Ochoa,  below 
the  mouth  of  the  San  Carlos,  the  minimum  com- 
puted discharge  on  May  10  was  16,300  and  the 
maximum  was  107,000  cubic  feet  per  second  on 
Xo vember  17,  the  variation  in  stage  being  13.35 
feet.  To  provide  for  extreme  cases,  however,  it 
is  estimated  that  the  river  above  the  San  Carlos 
may,  at  rare  inten-als,  imder  the  cumulative  dis- 
charges from  the  lake  and  river,  reach  a  possible 
maximum  of  100,000  second-feet  and  that  the 
San  Carlos,  a  flashv  and  torrential  stream,  mav 
add  100,000  more  to  this  quantity  in  the  lower 
section  for  a  short  time. 

The  Capacity  of  the  Channel. 

The  entire  river  bed  has  been  carefully  sur- 
veyed \dth  a  view  to  determine  its  carrying  ca- 
pacity imder  the  regimen  resulting  from  the 
creation  of  such  dams  and  locks  as  mav  be  found 
best  adapted  to  convert  it  into  a  navigable  chan- 
nel for  deep  draft  vessels.  The  upper  river  will 
require  dredging  from  the  lake  to  the  Castillo 
rapids,  and  as  the  channel  as  proposed  will  be  300 
feet  wide  at  bottom  and  extend  to  a  depth  of  30 
feet  below  the  lowest  lake  level,  this  cut  will 
largely  increase  the  cross  section  and  thus  enable 
a  larger  volume  to  be  discharged  without  any 
material  increase  of  velocity.  Moreover,  the 
river  falls  about  13.9  feet  below"  the  105  stiige  in 
the  lake  before  reaching  the  head  of  the  Castillo 
rapids  so  that  a  dam  farther  down  stream  im- 
l)ounding  this  water  would  still  further  augment 
the  cross  section  by  raising  the  surface.  As  the 
capacity  is  regulated  by  the  smallest  sections,  it 
is  necessarv  to  ascertain  their  location  and  effects 
upon  the  discharge  under  the  new  regimen. 


The  Controlling  Section. 

Under  existing  conditions  the  ruling  sections 
of  the  stream  are  found  to  be  at  stations  1494 
and  1515  near  the  head  of  the  Toro  rapids  and 
Castillo  rapids,  in  that  section  of  the  upper  river 
betw^een  Fort  San  Carlos  and  the  Castillo  Viejo, 
as  indicated  below.  The  relation  of  the  existing 
cross  section  of  the  stream  to  that  of  the  im- 
proved section  when  raised  to  the  upper  level  of 
the  lake  and  dredged  to  the  requisite  depth  of 
30  feet  with  a  bottom  width  of  300  feet,  is 
stated  in  square  feet  and  percentages. 

Relative  Areas  at  Controlling  Sections. 


Ijocation. 
Station. 

268 

680 
1,265 
1,494 
1,515 
1,665 
Castillo, 


Miles,  ^""^^^ft,"^^ 


5 


13 

24 

28J 

28f 

3H 


7,810 
7,697 
7,960 

2,948 
3,758 

6,435 


5- 

5' 


Enlargred  area,    Percentagre 
sq.  ft.  of  incieaee. 

I       94.6 

f        94.0 

116.0 

641.0 

775.0 


Lower  Machua,  6,060 


15,200 
15,920 
17,200 
21,840 
32,824 

23,406 
44,370 


264.0 
632.0 


From  this  it  appears  that  the  location  of  the 
controlling  section  would  be  changed  from  its 
present  position  to  a  point  5  miles  from  the  lake, 
while  the  area  of  that  section  would  be  very 
nearlv  doubled  at  a  lake  elevation  of  110  feet 
above  tide.  As  the  maximum  discharge  re- 
quired to  pass  through  this  section,  with  a  range 
of  6  feet  for  the  greatest  fluctuation,  would  not 
produce  velocities  exceeding  3.3  feet  per  second, 
such  a  discharge  would  not  materially  affect  the 
stability  of  the  channel  nor  its  navigation.  A 
further  discussion  of  the  rc*sulting  velocities 
under  different  volumes  of  discharge  is  submitr 
ted  by  Mr.  F.  L.  Stuart,  Assistant  Engineer, 
sho\\nng  that  at  no  other  })lace  in  the  channel 
would  the  velocity  be  as  great. 


10 


NICARAGUA  CANAL  COMMISSION 


Computed  Velocity  in  River  and  Canal  at  Vari- 
ous Points,  with  Different  Discharges,  re- 
ferred to  Lake  at  110: 


Location. 

Sta.  268 
in  Ri\ 

Sta.  680 
in  Ri\ 

Sta.  1265 
in  Ri 


30,000  50,000  DlgShar^a.  Velocity, 

cu.  ft.  cu.ft.  ^*?^,  f?^®*  feet  per 

Velocity,  Velocity,        ^'^  second, 

ft.  per  sec.  ft.  per  sec.       P®^  ^^• 


3.6 


8        K.  oo        55,000 

iver,P''  ""'^       35,000  2.3 


3.7 


'       h-^  3.1       J0,000 

iver,  I  40,000  2.5 


^'     ll.' 
iver,  J 


2.0 


70,000 
50,000 


4.1 
2.0 


Cut-Off  Palo  de  Arco  to  Isla  Grande. 
Surface  of  Water  110. 

Discharge,  Discharge, 
30,000  60,000 

Location.       cu.  ft.  cu.  ft. 

Velocity,    Velocity,  Various  discharges, 

ft.  per  sec.  ft.  iwr  sec.  cu.  ft.     Vel.       cu,  ft.       Vel. 

In  River,     1.16     1.86  2.4  1.66 

62,500  42,500 

In  Canal,    1.3       2.2  2.8  1.86 

Cut-Off  Sombrero  de  Quero  to  Santa  Cruz 

River. 
Surface  of  Water  110. 

Discharge,  Discharge, 
30.000  50,000 

Location.        cu.  ft.  cu.  it. 

Velocity,  Velocity.  Various  discharges, 

ft.  per  sec.  ft.  per  sec.  cu.  ft.    Vel.       cu.  ft.       Vel. 

In  River,     1.4       2.3  3.56  2.3 

75,000  50,000 

In  Canal, 
hot.  150 

In  River,    1.03     1.72  2.56  1.72 

75,000    50,000 
In  Canal, ) 


2.3       4.00 


5.0 


4.0 


hot.  250 


}>• 


0       3.23 


4.86 


3.23 


Cut-off  2  miles  west  of  Boca  San  Carlos. 
Surface  of  Wat^r  110. 

Discharge,  Discharge, 
30,000  50,000 

Location,      ou.  ft.  cu.  ft. 

Velocity,     Velocity,  Various  discharges, 

ft.  per  sec.  ft.  per  sec.  cu.ft.     Vel.       cu.  tt.       Vel. 

In  River,    0.6       1.0  2.01  1.0 

100,000  80,000 

In  Canal,    0.7       1.18  2.36  1.8 


2  Dams  Above  (\tt-Off,  H-Lock  System. 
Surface  of  Water  82.4. 

Discharge,  Disdiarge, 
30,000  50.0U) 

Location.       cu.  ft.         cu.  ft. 

Velocity,    Velocity,  Various  discharges, 

ft.  per  sec.  ft.  per  sec.  cu.  ft.     Vel.       cu.ft.       Vel. 

In  River,    0.8       1.35  2.7  — 

100,000  — 

In  Canal,    1.23     2.1  4.1  — 

2  Dams  Above  Cut-Off,  6-Lock  System. 
Surface  of  Water  73.2. 

Discharge,  Discharge, 
30,000  50.000 

location.       cu.  ft.         cu.  ft. 

Velocity,    Velocity,  Various  discharges, 

ft.  per  sec.  ft,  i>er  sec.    cu.ft      Vel.       cu  fi.       Vel. 

In  River,    0.83     1.30  2.77  1.2 

100,000  80,000 

In  Canal,    1.30     2.17  4.33  3.45 

This  table  further  demonstrates  that  instead 
of  having  velocities  exceeding  12  feet  per  second 
over  the  rapids,  which  would  he  submerged,  the 
maximum  current  in  the  river  under  a  discharge 
of  30,000  cubic  feet  would  not  exceed  2  feet  or 
IJ  miles  per  hour,  which  would  not  readily  dis- 
turb the  banks  of  this  section  of  the  stream. 
Under     ordinarv     conditions     and     throughout 

nearlv  this  entire  reach  the  velocities  wouM  be 

ft- 

less  than  one  foot  per  second. 

With  a  discharge  of  50,000  cubic  feet,  which 
is  higher  than  will  probably  (»ver  be  reached  in 
this  (upper)  part  of  the  river,  the  maximum  ve- 
locity through  the  controlling  sections  would  not 
therefore  much  exceed  3  feet  jxt  second,  impos- 
ing no  material  restrictions  on  navigation. 

Stability  of  Slopes. 

Xature's  Com}M?nsations. 

So  much  stress  has  been  laid  upon  the  exces- 
.sive  ])reci])itation  and  its  destructive  (effects  uix>n 
the  ])roposcd  works,  as  well  as  u])on  the  labor 
and  machinerv'  requiivd,  that  the  Commission  is 
impelled  to  call  attention  to  the  fact  that  the 


REPORT   OF   THE   COMMISSION 


11 


physical  features  of  the  country  furnish  the  most 
conWncing  and  conchisive  evidence  that  these 
uncontrolled  forces  are  not  so  injurious  as  has 
been  alleged,  for  the  angle  at  which  freshly 
made  earth-slopes  stand  is  found  to  be  much 
steeper  than  that  prevailing  in  our  more  north- 
ern latitudes,  where  they  are  also  exposed  to  the 
destructive  action  of  frost  and  the  internal  stress 
due  to  greater  ranges  of  temperature.  In  some 
cases  in  the  northwest  the  range  covers  160  de- 
grees, whereas  in  Nicaragua  the  greatest  fluctua-  • 
tion  seldom  exceeds  25  degrees.  The  absence  of 
frost  more  than  compensates  for  the  excessive 
downpour. 

Observ^ations  by  engineers  of  experience  in 
tropical  countries,  lead  them  to  believe  that  the 
same  security  and  greater  permanency  may  be 
obtained  with  less  first  cost  and  economy  of 
maintenance  by  making  the  side  slopes  steeper 
and  thus  reducing  the  prisms  of  cut  and  fill, 
than  by  employing  the  typical  sections  of  our 
own  latitudes.  Xature  compensates  for  the 
greater  rainfall  by  the  uniformity  of  heat  and 
moisture.  The  spontaneous  growth  of  vegeta-  * 
tion  revets  the  natural  surface,  clothing  it  with 
a  protecting  thatch  which  not  only  acts  as  an 
elastic  cushion  to  break  the  impact  but  also  to 
retain  the  water  and  thus  prevent  the  sudden 
and  destructive  floods  so  familiar  to  us  during 
the  spring,  when  the  rain  and  melting  snows 
combine  to  produce  their  maximum  effects. 

The  Board  of  1895,  in  referring  to  the  char- 
acter of  the  work  done  in  Grevtown  harbor,  re- 
marks  that  "  The  material  excavated  was  almost 
entirely  volcanic  sand,  similar  to  that  of  the 
beach.  .  .  .  When  piled  in  heaj^s  it  fonns  a  por- 
ous mass  through  wliich  the  toiTential  rainfalls 
descend  with  suq)risiiigly  little  effect  upon  its 
contour,  even  though  the  slopes  be  steep.  This 
feature  was  noted  both  in  the  mounds  of  dredg- 


ings  near  the  entrance  and  in  the  canal  banks, 
where  the  sands  dropped  from  the  dredge  chutes 
still  stood  seemingly  undisturbed  since  they  were 
put  there." 

Of  the  cuts  along  the  railroad  the  Board  also 
adds:  "The  cuts  have  heights  up  to  20  feet, 
^vith  slopes  from  vertical  to  45  degrees,  and  in 
most  cases  stood  with  an  extraordinary  stability 
under  the  tropical  downpours.  At  several,  the 
original  tool  marks  were  still  visible,  both  picks 
and  steam  shovel.  In  several  others,  there  had 
been  slides,  but  none  of  great  extent.  The 
ditches  were  generally  clean  and  in  but  few 
points  had  wash  reached  the  rail.  The  surface 
of  the  cuts  was  in  some  cases  protected  by  vines, 
but  in  most  was  quite  bare  unless  for  a  minute 
lichen. 

"As  these  clay  cuts  have  been  exposed  for 
over  three  years  to  the  severest  rainfall  of  record 
on  this  continent  and  were  found  in  better  con- 
dition on  the  whole  than  an  exposure  in  the 
United  States  for  a  single  winter  would  have  left 
them,  it  is  evident  that  the  absence  of  frost  more 
than  balances  the  tropic  downpour  and  for  the 
material  in  question  constructions  can  quite  as 
safely  be  designed  as  in  the  United  States.  .  .  . 
The  natural  growth  in  the  road-bed  was  unex- 
pectedly slight,  although  in  two  or  three  cases 
the  canebrakes  had  invaded  the  track. 

**  On  the  whole,  taking  into  account  the  con- 
dition of  the  sand  dumps  at  Greytown  and  of 
the  clay  cuts  and  fills  on  the  line  of  the  railroad, 
it  is  evident  that  the  heavy  rainfall  is  not  neces- 
sarilv  as  formidable  an  obstacle  to  outdoor  con- 
struction  as  might  be  supposed." 

The  Geologist,  Dr.  Hayes,  also  states,  con- 
cerning the  resistance  of  the  slopes  to  abrasion 
on  the  western  division,  that 

**  The  present  channel  of  the  Rio  Grande  is 
from  15  to  25  fi*et  in  depth  and  its  sides  are  gen- 


12 


NICARAGLTA   CANAL  COMMISSION 


erally    steo]>,    often    nearly    or    quiti^    vertical,  out  there  was  no  mortality  in  the  country.     The 
They  serve  to  show  the  capacity  of  the  material  constant  motion  of  the  wind,  sweeping  through 
to  staml   at  very  steep  slopes.     It  would  also  this  low  divide,  appears  to  I'emove  the  noxious 
probably  form  fairly  imix^rvious  embankments."  exhalations  which  characterize  other  portions  of 
There  is  no  reason,  therefore,  for  departing  the  isthmus.     Yellow  f(»ver  finds  no  habitat  at 
from  the  usual  engineering  ])ractice,  unless  it  be  ( Jreytown  and  even  when  im})orted  it  does  not 
to  make  the  slopes  steeper  and  thus  redu<'(»  the  become  ei)ideniic.     Abstemious  habits  and  care- 
cube  of  excavation  and  the  conseipient  cost  of  ful  police  of  camps  will  insuiv  as  gooil  health 
the  work.  amongst  laborers  as  will  be  found  in  many  lo- 
calities in  this  country.     The  climate  would  af- 
Saxitarv  and  CLniATir.  f^^.^  ^j^,  IqX^ov  question,  therefore,  chiefly  by  the 

The  impression  that  this  jiortion  of  the  isth-  lassitude  resulting  from  its  enervating  influence, 
mus  is  unasually  unhealthy,  is  eiToneous.     On         Assistant   Engineer  Stuart   says  that,   **  The 

the  contrarj',  the  Iwal  conditions  are  such  that  atmospheric  conditions  are  excellent,  and  for  the 

with    ordinarv    hygienic    precautions    the    risks  r^vvon  months  we  were  in  the  field,  we  worked  in 

from  disease  are  slight.  all  conditions  of  weather,  losing  but  one  entire 

The  frequent  rainfall  on  the  east  coast  fur-  day  on  account  of  a  heavy  down}>our  of  twelve 

nishes  an  ample  supply  of  frt^-^h,  soft  water  con-  houi*s." 

densed    directly    from    the   clouds;    the   porous  Tlu^  narrow  limits  within  which  the  temjx^ra- 

sandy  soil  absorbs  it  so  rapidly  as  to  prevent  ture  ranges  are  shown  from  a  few  stdected  ob- 

stagnation,   while  animal  refuse  is  quickly  re-  scrvations  at  various  stations  during  the  year  as 

moved  by  the  scavenger  birds  and  tish  con  tin-  below.     The  l{io  A'^iejo  station  is  locat<:»d  on  the 

ually  on  the  alert  for  food.  west(mi  slope  of  the  Cordilleras  east  of  the  lake 

With  their  light,  hx>se  clothing,  vegetable  and  at  a  higher  altitude  than  the  othei*s.  Hence 
diet  and  cleanly  habits,  the  natives  ^^eldom  suf-  its  greater  range  of  J50^.  This  uniformity  of 
fer  from  fevers.  Even  our  unacclimated  Ameri-  temi)erature  is  one  of  the  important  factors  in 
cans  passing  from  a  rigorous  winter  temperature  the  consideration  of  the  iK'rmanency  of  import- 
to  the  mild  region  of  the  trade  winds  were,  with  ant  works  as  well  as  in  the  health  of  the  inhabi- 
few  excej)tions,  exempt  from  febrile  complaints,  tants. 
and  amongst  the  large  number  of  engineers  sent 

Exhibit  ok  Extreme  Kanoe  of  the  Observed  Temperatire  in  Nicaragua. 

lA^cati«m.  Date,  1H96.         Maximum.       Minimum.       Dato,  18U8.       Kaiif^>. 

Brito  and  Tola  Stations Dec.  22,  88°  F.  75^^  E.  June  28,  13° 

Liis  Lajas  Station ifay  12,  91°  E.  7:]°  E.  Sept.  10,  18^' 

Rio  Viejo  Station Mar.  3,  97"^  E.  (>2^  E.  Mar.  12,  35° 

Eort  San  Carios  Station May  8,  91  °  E.  70°  E.  Mar.  28,  21  ° 

Sabalos  Station Mar.  20,  90°  E.  05.2°  E.  Dec.  25,  2-1.8^ 

San  Carios  Kiver May  7,  95°  E.  00°  E.  Eeb.  7,  29°      ' 

Ochoa  Station ..Oct.  1,  95°  E.  00.5°  E.  Jan.  3,  28.5° 

Deseado  River  Station May  25,  9 1  °  E.  05=^  E.  Jan.  3,  20° 

Greytown    Sept.  29,  90°  E.  09°  E.  .Mar.  14,  27° 


REPORT   OF   THE   COMMISSION 


13 


Earthquakes  and  Volcanoes. 

From  the  most  reliable  data  obtainable  the' 
Commission  believes  that  the  canal  region  is 
practically  exempt  from  any  seismic  influences 
of  sufficient  force  to  cause  destruction  or  danger 
to  any  part  of  the  canal  route  or  suspension  of 
its  traffic.  Dr.  C.  W.  Haves  has  treated  this 
question  fully  in  his  report.'     He  says  that: 

"  Earthquakes  due  to  the  dislocations  of  strata 
(faults)  are  perhaps  no  more  liable  to  occur  in 
the  vicinity  of  the  Nicaragua  Canal  Route  than 
elsewhere,  and  hence  thev  do  not  constitute  a 
danger  which  is  peculiar  to  this  region  more 
than  to  almost  any  other  in  which  a  ship  canal 
might  be  constructed." 

He  then  proceeds  to  discuss  those  due  to  vol- 
canic agencies  at  some  length  and  concludes 
that  those  activities  are  on  the  wane  and  so  re- 
mote from  the  route  as  not  to  constitute  a  men- 
ace.    In  quoting  from  Major  Button,  he  adds: 

"  Briefly,  then,  the  risk  of  serious  injury  by 
earthquakes,  to  the  constructions  proposed  for 
the  Pacific  section  of  the  canal  is  so  small  that  it 
ought  to  be  neglected;  .  .  .  also  that  the 
risks  to  the  Atlantic  section  are  still  smaller  than 
those  to  the  Pacific  section." 

Materials  for  Structural  Purposes. 

The  cost  and  durability  of  the  canal  are  also 
affected  by  the  character  and  distribution  of 
such  native  material  as  may  be  utilized  for  the 
purposes  of  construction.  These  consist  chiefly 
of  earth,  rock,  timber  and  sand,  all  of  which  are 
abundant  and  free.  Cement,  iron,  explosives, 
tools,  plant,  and  some  provisions  and  clothing 
will  need  to  be  imported  but  ^\all  be  exempt  from 
duty. 

Alluvium.' 

"  All  unconsolidated  material  w^iich  has  been 
transported  and  deposited  by  streams  is  classed 


'  See  Report  of  Dr.  Hayes,  Appendix  II. 


as  alluvium.  ...  It  varies  considerably  in 
composition,  dei)ending  ui>on  the  source  from 
which  it  was  derived  and  the  manner  in  which 
it  was  deposited.  It  varies  all  the  way  from 
coarse,  clean-washed  sand  or  gravel  to  the  finest 
clay.  It  may  for  convenience  be  separated  into 
three  sub-classes,  (1)  sand,  (2)  silt,  a  variable 
mixture  of  fine  sand  and  clay,  and  (3)  clay-silt, 
composed  chiefly  of  clay,  with  little  or  no  sand. 
All  three  subclasses  contain  variable  quantities 
of  vegetable  matter. 

"  The  alhudum  is  everywhere  of  such  charac- 
ter that  it  can  be  e^ly  handled  with  dredges. 
Almost  everywhere  the  silt  and  clay-silt  are  suffi- 
ciently solid  to  stand  at  moderate  slopes,  the 
slope  of  one  on  one  probably  being  sufficient. 
In  some  cases,  as  in  the  Florida  lagoon,  special 
precautions  may  be  needed  to  preserve  the  slopes. 
The  material  becomes  very  hard  when  dry,  and 
even  when  it  is  piled  up  so  that  the  water  can 
drain  off  it  becomes  comparatively  firm.  This 
is  shown  in  the  vertical  stream  banks  where 
drainage  is  possible,  while  the  same  material 
forms  a  soft  mud  in  the  swamps  at  some  distance 
from  the  stream  channels.  The  black  sand  when 
free  from  clay  is,  of  course,  quite  pensions  to 
water  and  would  not  be  suitable  for  banks  where 
the  water  level  was  permanently  different  on  its 
two  sides.  This  material,  however,  will  not  be 
encountered  beyond  the  site  of  the  first  lock  on 
the  proposed  low-level  line.  It  is  probable  that 
wherever  the  canal  is  more  than  lialf  in  excava- 
tion the  silt  will  form  banks  sufficiently  imper- 
vious to  hold  the  required  height  of  water  with- 
out the  addition  of  anv  other  material.  Where 
the  head  is  greater  than  fifteen  feet  it  may  be 
necessary  to  add  a  puddled  core  to  the  bank 
unless  the  latter  is  made  of  more  than  ordinary 
thickness.''  ^ 

OAND. 

The  black  volcanic  sand  of  the  east  coast  and 
lower  river  section  is  not  composed  of  the  partly 


14 


NICARAGUA  CANAL  COMMISSION 


decayed  minerals  derived  from  a  deeply  weath- 
ered rock,  but  is  made  up  entirely  of  finely  com- 
minuted fragments  of  fresh  volcanic  rock  evi- 
dently broken  up  and  ejected  by  explosive  vol- 
canic eruptions.  It  would  thus  make  a  good, 
sharp,  clean  material  for  hydraulic  mortar,  con- 
crete or  beton.  Its  specific  gravity  is  1 .  68  or 
104  lbs.  per  cubic  foot,  comparing  very  favor- 
ably with  the  best  building  sand  in  the  United 
States. 

Clay. 

Clay  of  excellent  quality  is  abundant  and  wtU 
distributed.  When  mLxed  in  suitable  propor- 
tions with  sand  and  gravel,  it  makes  an  admir- 
able puddling  material. 

"  Quartz  occurs  in  only  a  few  of  the  rocks,  so 
that  much  of  the  clay  is  remarkablv  free  from 
grit,  tough  and  compact.  Although  it  is  pene- 
trated by  numerous  roots  and  burrowing  insects, 
the  absence  of  frost  permits  it  to  remain  more 
compact  than  any  surface  clay  in  higher  lati- 
tudes. Next  to  the  silt  it  will  form  bv  far  the 
largest  part  of  the  excavation.  It  will  make  per- 
fectly impervious  embankments  if  some  means 
are  taken  to  puddle  it  as  it  is  deposited,  but 
probably  if  simply  dumped  in  the  bank  it  would 
be  pervious  to  water."  ' 

Wood. 

Numerous  large  trees  occur  in  the  forests 
along  the  river  and  on  the  border  of  the  lake, 
which  are  denser  and  stronger  than  our  Ameri- 
can oaks  and  pines.  The  clearing  of  the  canal 
route  will  also  furnish  a  large  number  of  cross- 
ties.  Some  of  these  native  woods,  according  to 
Col.  Childs,  will  last  above  ground  from  forty 
to  fifty  years.  The  Madera  Negra  is  one  of  the 
most  valuable  for  ties  and  is  abundant.     It  mav 


1  See  Report  of  Dr.  Hayes,  Appendix  II. 


also  be  obtained  for  dimension  timber  up  to 
thirty-foot  lengths  and  eleven  inches  square. 

The  Nispera  will  cut  in  lengths  of  fifty  feet 
and  square  eighteen  inches.  It  is  very  com- 
mon and  durable,  but  heaw.  Manv  other  va- 
rieties  exist,  as  the  Palo  Cortez,  Guachipilin, 
Roble,  Cocobole,  Pine,  Cedar,  Xiambaro,  Ca- 
oba  or  Mahogany,  Palo-de-Arco,  Granadillo, 
Guyacan,  Almendro,  Feniscaro,  etc.  The  ship- 
ment of  timber  is  one  of  the  industries  of  the 
port  of  San  Juan  del  Sur.  As  much  of  the  na- 
tive timber  is  valuable  for  export  and  as  no  mills 
exist  for  its  local  manufacture,  it  mav  doubtless 
prove  more  expedient  to  import  the  piling  and 
dimension  material  from  the  extensive  forests  of 
the  Southern  States  and  to  use  the  local  product 
mainly  for  fuel  and  ties. 

Shelter. 

There  is  also  ample  material  available  without 
cost,  for  the  protection  of  men  and  materials 
from  the  rain  and  sun.  The  usual  habitations 
of  the  natives  consist  of  a  carefully  laid  thatched 
roof,  substantially  built,  reaching  nearly  to  the 
ground,  with  walls  of  bamboo  or  adobe.  These 
afford  free  circulation  of  air  and  are  cool  and 
dry.  Their  only  cost  is  for  the  labor  of  erection, 
which  is  slight. 

The  fuel  in  general  use  is  wood,  which  is  cut 
and  stacked  under  shelter  on  the  banks  of  the 
river.  A  considerable  quantity  of  cord  w^ood 
can  be  secured  from  the  clearing  of  the  route 
and  adjacent  forests.  In  some  localities  water- 
power  may  be  made  available. 

Iron  and  Steel. 

These  metals  will  necessarily  be  imported,  but 
the  climatic  conditions  are  such  as  to  cause  re- 
markably little  deterioration.  Templates  of  the 
rails  which  have  been  exposed  to  the  rain  and  sun 


REPORT   OF  THE  COMMISSION 


15 


for  about  nine  vears  do  not  exhibit  anv  measnr- 

able  loss  in  section  of  weight.     The  spikes  also 

retain  the  sharp  edges  of  the  tool  marks  on  their 

heads  and  shanks.     Onlv  where  the  salt  water 

of  the  ocean  reaches  the  iron  rails  and  bolts  on 

the  pier  is  there  any  considerable  amount  of 

scale  visible. 

Stone. 

A  large  amount  of  material  on  the  route  of 
the  canal,  classified  as  rock  and  soft  rock,  will 
require  excavation  to  create  the  channel.  A 
portion  of  this  is  suitable  for  structural  pur- 
poses. On  the  western  division  the  rock  is 
generally  a  calcareous  non-fissile  shale,  inter- 
stratified  with  beds  of  sandstone  varying  from  a 
few  inches  to  two  or  three  feet  in  thickness. 
The  shales  constitute  the  greatest  bulk  of  the 
rock  to  the  eastward  of  Brito  Head,  where  the 
sandstones  of  the  northern  headland  are  too 
thin  for  use  as  building  stones  but  are  suitable 
for  concrete  or  rip-rap. 

About  half  a  mile  east  of  Brito,  however,  is 
found  a  group  of  heavy  sandstone  beds  forming 
a  spur  extending  into  the  Kio  Grande  valley. 
"  These  beds  would  probably  yield  a  good 
quality  of  dimension  stone;  would  be  easily 
quarried  in  dimensional  blocks  up  to  20  or  more 
inches  in  thickness;  w^ould  dress  readilv  and  be 
as  durable  as  the  average  sandstone."  * 

North  of  the  canal  line  at  Buen  Ketiro  is  a 
large  deposit  of  intruded  andesite  or  trap  which 
makes  a  verv  desirable  material  for  structural 
purposes. 

**  It  is  probable  that  all  the  material  on  the 
west  side  which  has  been  classed  as  soft  or  dis- 
integrated rock  can  be  excavated  with  a  steam 
shovel  without  blasting.  The  material  stands 
in  natural  slopes  of  60°  or  more  (to  the  hori- 
zontal) and  artificial  slopes  equally  steep  will 
probably  be  entirely  safe."  * 


I  See  Report  of  Dr.  Hayes,  Appendix  II. 


The  rocks  on  the  eastern  division  are  chiefly 
of  igneous  origin,  but  from  a  few  miles  below 
Castillo  to  half-way  between  Machuca  and  Boca 
San  Carlos  they  are  largely  sedimentary  with 
a  few  small  igneous  dikes. 

Xo  coarse  conglomerates  nor  pure  limestones 
have  been  discovered  in  this  formation,  although 
thev  mav  occur.  "  The  beds  of  massive  sand- 
stone  exposed  on  Machuca  creek  being  to  a  large 
extent  free  from  joints  could  probably  be  quar- 
ried for  dimensional  building  stone,  which  would 
be  easily  worked  and  fairly  durable."  * 

The  principal  varieties  of  the  igneous  rock 
found  in  this  section  are  augite-andesite,  olivine 
basalt,  hypersthene  basalt  and  dacite.  The  first 
three  are  commonly  known  as  trap  rocks.  They 
are  generally  compact  and  heavy.  The  dacite  is 
lighter  than  the  trap  and  somewhat  softer.  (This 
w^as  called  conglomerate  by  the  Canal  Company.) 

The  basalt  (trap)  extends  from  the  Boca  San 
Carlos  eastward  bevond  the  San  Francisco  hills, 
forming  the  Sarapiqui  hills  and  others  bordering 
the  lower  portion  of  the  San  Juan  river  as  well 
as  those  in  the  vicinity  of  Silico  lake,  and  is 
suitable  for  dams,  jetties  and  concrete. 

The  dacite  is  found  at  lower  Ochoa  and  Tam- 
bor  Grande,  where  it  comes  to  the  surface  and 
continues  to  the  Eastern  Divide.  It  is  there 
interbedded  with  the  andesite  tuffs  and  basalt 

Associated  with  the  above-named  massive 
rocks  is  a  group  of  fragmental  igneous  rocks 
whose  members  vary  from  coarse  conglomerate 
or  breccia  to  beds  of  fine  volcanic  ash.  The 
coarser  varieties  resemble  in  their  physical  prop- 
erties the  igneous  rocks  from  which  they  are  de- 
rived, while  the  fine  ash  is  generally  talcose  and 
crumblQs  on  exposure  to  the  air. 

Deposits  of  hard  rock  also  exist  near  the  site 
(^f  Lock  Xo.  1  of  the  Canal  Company's  line  to 
which  the  railroad  has  been  built. 


16 


NICARAGUA  CANAL  COMMISSION 


Several  outcrops  of  rock  reported  to  be  suit- 
able for  jetty  construction  exist  on  the  coast 
at  Point  of  Rocks  and  at  Monkey  Point,  but  no 
samples  from  these  ledges  have  been  secured. 
The  quarries  are  readily  accessible  from  the  sea 
and  furnish  material  for  ballast  to  coasters. 

Classification  and  Weathbrino. 

"  The  three  classes  of  materials — alluvium, 
residual  clay  and  soft  rock — should  be  consid- 
ered as  earth  in  making  estimates  for  excavation. 
The  soft  rock,  however,  may  require  some  blast- 
ing, particularly  toward  the  bottom  and  where 
it  contains  very  large  boulders.  It  will  stand 
with  much  steeper  slopes  than  the  silt  and  clay 
and  will  be  less  liable  to  slip.  Not  being  plastic, 
it  will  also  support  a  heavier  load,  and  hence  may 
be  relied  upon  for  foundations  where  the  weight 
of  the  structure  is  not  excessive.  For  these 
reasons  it  seems  desirable  to  make  the  distinction 
between  clay  and  soft  rock  wherever  possible."  * 

The  weathering  of  rocks  is  brought  about  by 
two  processes — rock  disintegration  and  rock 
decay.  The  first  varies  directly  and  the  second 
inversely  with  latitude  when  humidity  is  con- 
stant. The  first  process  depends  on  changes 
.  of  temperature  and  expansion  of  interstitial 
water  by  freezing,  hence  is  inactive  in  the 
tropics.  The  second  process  depends  on  high 
temperature  and  a  rapidly  decaying  vegetation, 
hence  is  active  in  the  tropics.  Special  atten- 
tion is  directed  to  the  fact  that  it  is  chiefly  the 
first  process  of  disintegration  which  is  inimical 
to  the  permanence  of  structures,  and  hence  that 
their  relative  durability  will  be  greater  in  the 
tropics  than  in  higher  latitudes. 

Such  being  in  brief  the  physical  conditions 
of  the  route,  it  remains  to  determine  the  dimen- 
sions,  which,   all  things  considered,   will   best 


1  See  Report  of  Dr.  Hayes,  Appendix  II. 


subserve  the  interest  of  the  world's  commerce  in 
making  this  transit  of  the  isthmus. 

Dimensions  of  Canal. 

To  provide  ample  facilities  for  the  safe  and 
expeditious  passage  of  vessels,  the  trunk  of  the 
water-way  has  been  considerably  enlarged  over 
that  of  any  previous  project.  The  dimensions 
adopted  by  the  Commission  as  the  basis  of  the 
estimates  are  as  follows: 

The  canal  nowhere  to  be  less  than  30  feet  in 
depth.  The  width  varying  with  the  local  con- 
ditions as  follows:  From  Grey  town  harbor  to 
Boca  San  Carlos  the  bottom  width  to  be  150 
feet  with  slopes  in  earth  of  1  :  1  and  in  alluvial 
silt  of  1  :  2.  In  hard  rock  vertical  sides  up  to 
40  feet  from  the  bottom,  then  slopes  of  5  :  1. 
In  soft  rock  the  slopes  to  be  2  :  1. 

In  the  river  the  \Wdth  at  bottom  to  be  300 
feet,  with  slopes  of  1  :  2  with  enlargements  at 
the  bends,  and  at  the  eastern  end  of  the  lake  the 
excavation  to  be  600  feet  wide  at  the  outer  end, 
decreasing  to  300  feet  at  the  river,  and  having 
slopes  of  1  :  5  to  the  depth  of  6  feet  and  then 
1:3;  for  all  routes  from  the  Caribbean  sea  to 
the  lake,  excepting  the  Menocal  route,  the  same 
dimensions  are  used.  The  bottom  width  of  the 
canal  from  the  lake  to  the  Pacific  to  be  150  feet, 
with  slopes  as  on  the  east  side,  and  the  compu- 
tations have  been  based  upon  a  minimum  lake 
elevation  of  104  feet  above  mean  sea  level, 
Caribbean  sea,  as  a  datum.  The  minimum 
radius  is  limited  to  3000  feet  with  enlargements 
of  width  in  bends  varv'ing  according  to  the  de- 
gree of  curvature. 

The  locks  are  80'  x  30'  x  665'  between  quoins, 
giving  an  available  length  of  620  feet  with  varia- 
ble lifts. 

Estimates  were  also  made  upon  numerous 
modifications  of  the  above  dimensions. 


REPORT   OF   THE   COMMISSION 


17 


10.3 

9.1 

50.0 

131.0 
84.0 
73.0 

210.0 


For  convenient  reference  and  comparison  with 
the  canal  prism  as  proposed  by  the  Maritime 
Canal  Company,  the  areas  of  the  several  cross 
sections  and  the  percentages  of  increase  are 
stated  herewith: 

Area  of  cross 
sections  in  wiuaro  Per  cent,  of 
feet.  increase. 

Between  jetties,  Greytown,  23,400 
Entrance  to  harbor.   Grey- 
town    \    14,700 

Coastal  section 6,300 

Canal  proper 5,400 

Through  rock 4,500 

In  the  river  (in  rock) 9,900 

In  the  river  (in  earth) ....    10,800 

I'^t^^i*'^^ {  is%l 

WEST    SIDE. 

Area  of  cross 
sections  in  square  Per  cent,  of 
feet.  increase. 

Western  Divide 4,500         50.0 

Across  coastal  plain 5,850  8.0  less 

Distances  along  the  line  of  the  Canal  route  pro- 
posed by  this  Commission  from  the  seven- 
fathom  curve  in  the  Pacific  ocean  to  the 
seven-fathom  cur\'e  in  the  Caribbean  sea: 

Miles. 

1.  Brito  Harbor 0.93 

2.  Brito  to  Buen  Ketiro 8.12 

3.  Buen  Retiro  to  west  side  of  lake 8.71 

4.  Lake  Nicaragua 71.34 

5.  East  side  Lake  Nicaragua  to  Boca  San 

Carlos 5G.96 

6.  Boca  San  Carlos  to  Sarapiqui 21.59 

7.  Sarapiqui  to  Greytown 20.59 

8.  Greytown  Harbor 1.74 


Total 189.98 

Kegulatiox  of  the  Lake  Level. 

All  plans  for  a  canal  by  the  Nicaragua  route 
contemplate  using  the  lake  as  the  summit  for  the 


canal  and  as  a  feeder.  The  regulation  of  its 
level  is  therefore  a  matter  of  the  greatest  im- 
portance. 

It  is  known  with  reasonable  certainty  that  the 
lake  has  varied  in  its  elevation  above  sea  level 
as  much  as  13  feet.  It  has  probably  been  as 
low  as  98  feet  above  mean  sea  level  and  as  high 
as  111  feet  above  the  same  plane.  These  ex- 
tremes have  occurred  at  relativelv  remote  inter- 
vals,  but  their  occurrence  must  be  admitted, 
and  their  recurrence  in  the  absence  of  regulating 
works  must  be  reasonably  anticipated.  It  is  also 
known,  as  a  result  of  the  observations  of  1898, 
that  notwithstanding  the  losses  due  to  the  out- 
flow through  the  San  Juan  river  and  to  evapora- 
tion, the  lake  has  risen  as  much  as  two  feet  in 
six  weeks. 

The  higher  the  lake  is  held  the  less  will  be  the 
excavation  in  the  upper  level,  and  as  this  is  a 
heavy  item  in  the  cost  of  construction,  the  effort 
has  always  been  to  keep  that  level  up  as  high  as 
practicable,  without  causing  unnecessary  dam- 
age to  private  property.  On  the  other  hand, 
a  spillway  of  capacity  sufficiently  great  to  pre- 
vent the  lake  from  rising  is  expensive.  The 
problem,  therefore,  is  how  best  to  meet  the  vary- 
ing conditions.  A  careful  investigation  has 
been  made  of  the  discharge  of  all  streams  of 
importance,  measurements  of  rainfall  observed 
at  points  widely  distributed  throughout  the 
basin,  and  the  rate  of  evaporation  from  the  lake 
surface  determined. 

The  area  of  Lake  Nicaragua,  in  round  num- 
bers, is  3000  ?i(iuare  miles,  nearly  2,000,000 
acres.  The  drainage  area,  including  both  lakes, 
is  about  12,000  square  miles.  During  the  dry 
season  of  1898  measurements  were  taken  to  de- 
termine the  total  inflow  into  Lake  Nicaragua, 
which  was  found  to  be  onlv  al)ont  1700  cubic 
feet  per  second,  showing  that  in  the  dry  season 


18 


NICARAGUA   CANAL  COMMISSION 


the  inflow  into  the  lake  is  very  small,  scarcely 
worth  considering.  Nearly  all  the  streams 
showed  evidences  of  being  stagnant  several 
months,  yet  the  year  1898  was  one  of  more  than 
average  rainfall. 

Kainfall. 

Observations  to  determine  rainfall  have  been 
kept  at  Rivas  for  the  last  19  years.  During  the 
year  1898  obsers^ations  were  taken  at  several 
scattered  stations  in  the  drainage  basin  to  deter- 
mine the  rainfall  of  the  lake  region.  These 
records  are  given  in  the  accompanying  ap- 
pendices. 

Comparing  the  records  at  Rivas  for  the  year 
1898  with  those  for  the  other  points,  it  will  be 
noted  that  the  rainfall  at  Rivas  was  greater  than 
the  averiage  for  other  parts  of  the  basin ;  that  at 
Rivas  being  108  inches  and  the  average  in  the 
basin  78  inches,  a  difference  of  about  28  per 
cent,  in  favor  of  Rivas.  This  might  at  first 
appear  anomalous,  but  it  may  be  accounted  for 
by  the  peculiar  topographical  features  of  the 
country  in  connection  with  the  prevailing  winds. 
It  will  therefore  be  assumed  that,  in  order  to 
obtain  the  rainfall  in  the  basin  for  other  years 
than  that  of  1898,  the  Rivas  record  will  have  to 
be  reduced  by  28  per  cent.  The  number  of 
observation  stations  in  the  basin  are  not  great, 
but  they  offer  a  basis  for  estimating  rainfall  in 
those  years  for  which  there  is  no  other  record 
than  that  of  Rivas. 

There  are  two  distinctly  marked  seasons  in 
the  drainage  area  of  the  lake — the  wet  and  the 
dry.  The  latter  begins  about  December  15  and 
lasts  until  about  May  15,  a  period  of  five  months. 
The  wet  season  then  begins  and  lasts  until  De- 
cember 15  following.  This  period  has  a  dura- 
tion of  about  seven  months.  It  is  probable, 
however,  that  the  length  of  the  wet  and  dry  sea- 


sons may  vary  in  some  years,  but  it  is  well  un- 
derstood among  the  people  in  that  region  that 
those  are  the  dates  from  which  they  are  reck- 
oned, and  the  observations  for  the  year  1898 
confinn  this. 

Evaporation. 

The  amount  of  evaporation  as  determined  for 
the  year  1898  was  52  inches.  That  year  was 
an  abnormally  wet  one  and  it  is  therefore  prob- 
able that  the  evaporation  was  somewhat  below 
the  average.  Mr.  Davis  estimates  a  normal 
annual  aggregate  at  about  60  inches,  or  five  feet. 
The  amount  of  evaporation  in  the  lake  itself  is 
greater  during  the  dry  and  less  in  the  wet  period. 
It  has  been  taken  at  4  inches  per  month  during 
the  wet  period,  and  6  inches  during  the  dry, 
which  corresponds  closely  with  the  observations 
for  1898. 

These  results  have  been  checked  by  the  Com- 
mission's study  of  the  exhibits,  as  follows: 

From  Plate  XVIII,  Appendix  HI,  it  appears 
that  during  the  year  of  1898,  throughout  which 
careful  observations  were  made,  the  lake  fell 
about  3.09  feet  between  January  6  and  May  15, 
a  period  of  131  days  or  4.5  months,  while  in  the 
following  season  of  rainfall  it  rose  4.72  feet  by 
December  5,  when  it  again  began  falling.  The 
net  gain  in  storage  during  this  entire  year  from 
January  5,  1898,  to  January  5,  1899,  was  15.6 
inches. 

It  will  be  observed  that  during  that  portion  of 
the  season  beginning  February  1  and  ending 
May  15  the  lake  surface  declined  uniformly  (the 
slight  fluctuations  being  due  to  wind  and  not  to 
rainfall),  and  that  in  this  time  the  total  rainfall 
did  not  exceed  2f  inches  over  the  lake  surface. 
The  run-off  from  the  parched  ground  at  this  sea- 
son is  practically  zero.  Hence  the  only  gain 
was  the  direct  rainfall  while  the  losses  were  those 


REPORT   OF  THE  COMMISSION 


19 


due  to  evaporation  and  outflow,  which  latter 
quantity  was  measured  by  continuous  observa- 
tions at  the  Sabalos  station  on  the  San  Juan 
river,  the  onlv  outlet. 

The  outflow  between  February  1  and  !^[ay  15 
is  given  as  2,817,748  acre-feet,  equivalent  to  a 
vertical  depth  over  the  lake  area  (2,000,000 
acres)  of  1.408  feet.  If  this  be  deducted  from 
the  loss  in  storage  and  rainfall,  which  is  2.840 
feet,  it  leaves  1.432  feet  loss  due  to  evaporation 
in  104  days,  or  a  diurnal  rate  of  .165  inch 
(i"),  or  5  inches  per  month,  or  a  rate  of  5.00 
feet  per  annum  for  a  dry  year.  This  being  de- 
duccd  during  the  dry  season  would  doubtless 
represent  the  maximum  for  the  year. 

Run-off. 

The  run-off  or  inflow  to  the  lake,  from 
rainfall  on  its  drainage  basin  exclusive  of  the 
lake  proper  for  the  year  1898,  has  been  found 
to  be  about  30  per  cent,  of  the  rainfall.  This 
is  computed  as  follows:  The  average  rain- 
fall at  six  stations  in  the  basin  of  Lake  Nica- 
ragua for  1898,  was  78.29  inches.  During  that 
vear  the  lake  rose  18  inches.  The  outflow  if 
held  would  have  raised  the  lake  84  inches. 
Evaporation  as  determined  was  52  inches,  so 
that  if  there  had  been  no  outflow  nor  evapora- 
tion the  lake  would  have  risen  154  inches.  Of 
this,  78.29  was  by  direct  fall  on  the  lake,  leav- 
ing 75.7  inches  as  the  rise  due  to  the  fall  on 
the  land,  or  the  rim-off.  The  area  of  the  lake 
is  3000  square  miles;  the  area  of  the  tributary 
basin  is  9900  square  miles.  The  latter  is,  there- 
fore,  3.3  times  that  of  the  former.  Dividing 
the  inflow  into  the  lake,  75.7  inches,  by  3.3, 
tlio  ratio  of  the  lake  surface  to  the  exterior 
drainage,  we  have  22.94  inches  as  the  rise 
due  to  run-off.  This  is  29.3  per  cent,  of  the 
rainfall. 


Lockage. 

When  the  canal  is  built,  the  lake  will  be 
drawn  upon  for  water  for  lockage  and  for  power. 
There  will  also  be  some  leakage,  the  amount 
depending  largely  on  the  kind  of  dams  and 
waste-ways  used.  The  estimate  for  leakage  is 
necessarily  arbitrary,  but  a  computation  based 
on  large  traffic  through  the  canal  gives  three 
inches  as  the  estimate  for  annual  requirements 
for  lockage,  leakage  and  power. 

Regulation. 

The  surface  of  the  lake  is  acted  upon  by  sev- 
eral opposing  forces.  They  must  be  so  regulated 
that  its  fluctuations  can  be  controlled  within 
proper  limits.  Evaporation,  outflow  and  use  of 
the  canal  will  lower  the  lake's  level.  Rainfall 
and  inflow  will  raise  it.  Water  must  therefore 
be  stored  for  evaporation  and  use,  and  the  ex- 
cess of  rainfall  and  inflow  be  discharged.  For 
purposes  of  storage  against  evaporation  years  of 
minimum  rainfall  must  be  considered,  and  for 
determining  spillway  capacity  years  of  maximum 
rainfall. 

The  data  for  an  absolute  determination  of 
these  problems  would  necessitate  a  series  of  ob- 
servations extending  over  many  years.  But 
with  the  records  for  1898  in  connection  with  the 
rainfall  records  of  Rivas  for  the  past  19  years, 
conclusions  may  be  reached  which,  while  they 
may  not  be  absolutely  correct,  will  be  sufficiently 
close  for  all  practical  purposes. 

The  year  of  minimum  rainfall,  as  determined 
by  the  Rivas  record,  is  1890.  During  that  year 
31.81  inches  of  rain  fell.  If  this  be  reduced 
by  28  per  cent.,  the  difference  between  Rivas 
and  the  average  of  other  parts  of  the  basin,  we 
have  22.9  inches  as  the  average  for  the  basin  in 
an  extreme  drv  vear.  It  is  well  known  that 
variations  in  annual  rainfall  are  greater  at  sin- 


20 


NICARAGUA  CANAL  COMMISSION 


gle  stations  than  over  an  extended  area.  It  is 
therefore  probable  that  this  estimate  is  too  low 
for  a  very  dry  year.  Twenty-eight  inches  have, 
therefore,  been  assumed  as  the  minimum  annual 
rainfall  in  (he  basin. 

The  estimated  run-off  for  1898  was  29.3  per 
cent,  of  the  rainfall,  and  as  the  nm-off  will  di- 
minish with  the  diminution  of  rainfall,  25  per 
cent,  of  the  rainfall  has  been  taken  as  the 
average  for  a  dry  year.  We  then  have  28  inches 
falling  directly  on  the  lake  and  28  inches  on  the 
drainage  area  tributary  thereto.  The  latter  be- 
ing about  9900  square  miles,  enough  water 
would  fall  on  the  land  to  raise  the  lake  23.1 
inches.  This  added  to  that  falling  direct  would 
raise  the  lake  51.1  inches  if  all  sources  of  loss 
were  cut  off.  But  the  loss  from  evaporation 
would  be  about  60  inches,  and  three  inches  would 
be. lost  by  lockage,  leakage  and  use — a  total  of 
63  inches,  or  5  feet  and  3  inches.  There  would 
then  be  a  deficit  of  11.9  inches  at  the  end  of 
the  year.  If  the  year  ends  with  the  end  of  the 
wet  period,  the  succeeding  dry  period  will  be 
begim  with  this  deficit.  For  this  period,  lasting 
about  5  montlis,  during  which  the  lake  would 
receive  practically  no  rain,  and  evaporation 
would  be  at  the  maximum,  the  loss  to  the  lake 
would  be  30  inches  for  evaporation  and  1^  inches 
for  lockage,  leakage,  etc.,  total  loss  31-^  inches, 
which,  added  to  the  deficit  of  11.9  inches,  gives 
43.4  inches  as  the  deficit  at  the  beginning  of  the 
wet  season,  when  the  lake  would  probably  fill 
up  again.  Temporary  storage  of  about  4  feet 
in  the  lake  is  therefore  needed  to  provide  for 
evaporation  and  use  in  a  time  covering  two  dry 
periods  and  one  wet  one.  In  other  words,  if 
the  lake  had  been  at  108  at  the  beginning  of  the 
first  dry  period,  it  would  have  fallen  to  104  at 
the  end  of  the  succeeding  dry  period. 

Substantially  the  same  result  is  reached  by 
^Ir.  Wheeler  in  another  way  (see  his  report). 


In  a  year  of  maximum  rainfall  and  minimum 

*  

evaporation  the  conditions  are  revei'sed.  The 
problem  will  be  to  get  rid  of  surplus  water  and 
prevent  the  lake  from  rising  to  a  high  level. 

The  year  of  maximum  rainfall,  according  to 
the  Rivas  record,  was  in  1897,  when  123  inches 
fell.  Keducing  this  by  the  28  per  cent,  ratio, 
we  have  a  rainfall  in  the  basin  of  88.6  inches  for 
the  maximum  year.  As  l>efore  stated,  the  varia- 
tion in  annual  rainfall  over  a  large  area  is  not 
as  great  as  it  is  at  one  station.  It  is  therefore 
probable  that  for  the  entire  basin  this  estimated 
rainfall  is  too  great.  Suppose  it  be  taken  at  84 
inches,  or  7  feet,  there  results: 

Rainfall  direct  on  the  lake.  .    84  inches 
Run-off,  30  per  cent.,  about.    84 


Total  inflow 168 

Deduct  for  evaporation  and 
use   03 


u 


10 


i> 


**  =8'  9 


ff 


This  represents  what  must  be  taken  care  of 
by  storage  and  discharge. 

This  rainfall  will  not  be  extended  uniformlv 
over  a  year,  but  most  of  it  will  fall  within  the 
wet  season  of  seven  months.  A  mean  discharge 
of  about  40,000  cubic  foot  i)er  second  would 
discharge  it  all  in  this  time  Or,  if  four  feet  be 
stored  in  the  lake,  a  moan  dij^charge  of  22,000 
cubic  foot  per  second  would  take  oaro  of  it.  In- 
asmuch as  it  is  imposv-iihlo  to  know  in  advance 
whether  the  rainfall  of  a  season  is  to  bo  heavy  or 
light,  it  will  not  l)e  safe  to  begin  discharging  at 
the  full  capacity  of  the  outlet  imtil  enough  water 
has  been  stored  for  possible  doficioncies.  Con- 
sequently, instead  of  having  seven  months'  time 
in  which  to  discharge  the  sui'plus,  a  large  part  of 
it  might  have  to  be  discharged  in  a  loss  time, 
and  a   spillway   of  greater  capacity  would   be 


REPORT   OF  THE   COMMISSION 


21 


needed.  With  a  spillway  capacity  of  50,000 
cubic  feet  per  second  the  entire  siirplns  could 
be  handled  in  al>out  92  davs. 

The  following  method  is  used  by  Mr.  E.  S. 
Wheeler  for  determining  the  amount  of  water 
to  be  taken  care  of  in  years  of  maximum  rain- 
fall: 

"Between  June  18  and  October  29,  1898,  a 
period  of  132  days,  the  rainfall  at  Rivas  was 
70.30  inches;  the  lake  rose  48.00  inches;  the 
outflow  lowered  it  32.70  inches  and  the  evapora- 
tion of  the  lake  surface  lowered  it  10.38  inches. 
Therefore,  if  there  had  been  no  evaporation  on 
the  lake  nor  outflow  from  it,  it  would  have  risen 
97.04  inches. 

"  Between  May  17  and  October  27,  1897,  a 
period  of  104  days,  the  rainfall  at  Rivas  was 
112.42  inches.  This  was  the  period  of  greatest 
rainfall  shown  in  the  Rivas  records  since  1879. 
The  amount  of  fluctuation  in  the  surface  of  Lake 
Nicaragua  caused  by  this  rainfall  was  not  ob- 
served; an  attempt  will  be  made  to  determine  it 
by  comparison  with  the  wet  portion  of  1898, 
when  both  fluctuations  and  rainfall  were  care- 
fully measured.  The  problem  may  then  be 
briefly  stated  as  follows:  If  a  rainfall  of  70.30 
inches  in  132  davs  would  cause  a  rise  in  the  lake 
surface  of  97.04  inches,  w^hat  rise  would  be 
caused  bv  a  rainfall  of  112.42  inches  in  104 
days?  The  ratio  between  rainfall  and  change 
in  lake  level,  as  given  in  the  preceding  table, 
cannot  be  used  for  this  problem,  because  in  this 
case  only  portions  of  a  season  are  considered. 
At  the  beginning  of  these  periods  the  streams 
and  marshes  were  drained  and  empty;  at  the 
end  they  were  overflowing  and  the  entire  nm- 
off  due  to  the  rainfall  had  not  vet  occurred. 
Therefore,  this  problem  must  be  solved  as  a 
special  case.  If  the  rise  w^as  exactly  propor- 
tional to  the  rainfall  it  would  be  143.7  inches, 


provided  there  w^as  no  evaporation  on  the  lake 
or  outflow  from  it.  It  is,  however,  probable  that 
in  this  case  as  in  the  preceding  one,  the  greater 
dailv  rate  of  rainfall  in  1897  w-ould  cause  the 
lake  to  rise  slightly  more  than  the  proportional 
amount.  An  examination  shows  that  the  daily 
rate  of  rainfall  in  1897  was  18  per  cent,  greater 
than  in  1898.  losing  the  ratio  as  before,  the 
rise  in  the  lake  would  be  22  per  cent,  greater. 
Applying  this  per  cent.,  the  computed  rise  in  the 
lake  for  1897  would  be  increased  from  143.7 
inches  to  148.58  inches.  This,  then,  is  the  esti- 
mated amount  of  fluctuation  that  would  have 
occurred  during  the  period  of  greatest  rainfall 
of  the  last  20  years  if  there  had  been  no  evapora- 
tion on  the  lake  or  outflow  from  it. 

"  The  question  as  to  what  amount  of  fluctua- 
tion in  the  lake  will  be  necessary  to  take  care  of 
this  rainfall  will  next  be  considered.  The  esti- 
mated rise  of  148.58  inches  must  be  provided  for 
by  evaporation,  outflow  and  temporary  storage  in 
the  lake. 

"  Assuming  the  ratio  of  evaporation  from  the 
lake  surface  to  be  the  same  as  in  1898,  it  would 
for  the  104  days  amount  to  20.97  inches.  Sub- 
tracting this  from  148.58  inches  leaves  127.01 
inches  that  must  be  provided  for  by  the  outflow 
and  temporary  storage. 

"  The  lake  has  an  area  of  3000  square  miles; 
a  rise  in  its  surface  127.01  inches  would  be 
equivalent  to  889,408,018,000  cubic  feet.  If 
this  should  nm  out  of  the  lake  in  104  days  the 
mean  discharge  would  be  02,709  cubic  feet  per 
second  and  there  would  be  no  change  in  the 
elevation  of  the  lake  surface.  If  the  lake  should 
be  permitted  to  rise  one  foot  then  the  mean  dis- 
charge would  be  reduced  to  50,800  and  each  ad- 
ditional foot  that  the  lake  is  allowed  to  rise 
w^ll  reduce  the  mean  rate  of  discharge  by  an 
equal  amount.     The  following  table  shows  the 


22 


NICARAGUA  CANAL  COMMISSION 


required  rate  of  diseliarge  for  each  foot  of  fluc- 
tuation : 

0  feet  require  62,800  cubic  feet  of  discharge. 

1  "         "       56,900     " 

2  "         "       51,000     " 
3-    "         "       45,100     '' 

4  "         "       39,200     " 

5  "         "       33,300 


kk 


<c 

ik 

a 

<( 

(( 

a 

a 

iC 

(( 

u 

"  It  appears  from  this  table  that  if  a  waste- 
way  having  a  capacity  of  33,000  cubic  feet  per 
second  be  provided,  the  fluctuation  in  the  lake 
could  be  limited  to  five  feet  for  rainfall  as  great 
as  any  that  has  occurred  in  the  last  twenty  years. 

"  Since  the  canal  itself  will  incidentally  pro- 
vide waste-ways  exceeding  this  in  capacity,  it 
appears  that  not  more  than  five  feet  of  rise  will 
be  caused  by  the  largest  rainfall.  Therefore,  no 
addition  need  be  made  to  the  six  feet  already 
provided  for  dry  periods." 

The  Commission  has  therefore  concluded  that 
in  any  plan  of  a  canal  by  the  Nicaragua  route  a 
spillway  of  50,000  cubic  feet  per  second  capacity 
should  be  provided,  and  that  the  lake  may  vary 
in  its  level  from  elevation  104,  the  minimum,  to 
110,  the  maximum. 

The  endeavor  would  be  to  approach  the  dry 
season  with  the  water  level  of  the  lake  at  about 
108,  and  during  that  dry  season  to  draw  it 
down  to  106  if  it  did  not  go  to  that  level  from 
natural  causes.  At  the  beginning  of  the  wet 
season  the  lake  would  be  allowed  to  rise,  but 
when  it  reached  108  the  spillway  would  be  op- 
ened, gradually  at  first,  and  at  its  full  capacity  if 
necessary.  In  this  way  there  would  be  a  margin 
of  four  feet  for  the  lake  to  fall  in  dry  seasons 
and  the  same  amount  for  it  to  rise  during  wet 
seasons.     This  is  believed  to  be  ample. 

The  possibility  of  securing  complete  control 
is  manifest  by  inspection  of  Plate  XlXa,'  which 


1  See  Plate  XlXa  iu  Atlas. 


shows  that  had  all  the  water  entering  the  lake 
been  impounded,  the  surface  during  the  first 
twenty  days  of  January,  1898,  would  have  risen 
throe  inches,  or,  since  there  was  no  rainfall, 
that  the  nm-off  and  seepage  from  the  previous 
season  were  still  feeding  it. 

From  this  period  it  would  then  have  declined 
quite  uniformly  from  loss  by  evaporation  until 
the  end  of  the  dry  season,  May  15,  when  it 
would  have  stood  at  an  elevation  of  104.07 
above  datum,  after  which  it  bore  a  nearlv  con- 
stant  relation  to  the  accumulated  rainfall  and 
would  have  reached  its  highest  level  of  113.69 
on  January  20,  1899,  a  gain  of  9.6  feet  in  about 
eight  months  had  all  the  water  been  held.  If, 
on  the  contrary,  it  had  been  desired  to  prevent 
any  further  rise  at  any  particular  stage,  even  the 
lowest,  it  might  have  been  done  by  a  spillway 
having  a  capacity  of  discharge  indicated  by  the 
red  line  of  the  chart  which  represents  an  incre- 
ment at  the  rate  of  45,940  cubic  feet  per  second. 
With  this  spillway  capacity  for  this  year  the 
lake  could  have  been  held  at  any  desired  stage, 
or  by  a  reduction  of  the  discharge,  it  could  have 
been  allowed  to  fluctuate  within  anv  reasonable 
limits. 

A  spillway  of  50,000  cubic  feet  capacity  di- 
vided between  the  eastern  and  western  outlets 
will  afford  ample  facilities  for  the  regulation  and 
control  of  the  lake  and  its  drainage. 

The  relation  of  such  a  spillway  capacity  to  the 
observed  fluctuations  during  1898  may  be  exhib- 
ited graphically  by  assuming  this  quantity  of 
water  to  be  poured  into  the  lake  basin  and  draw- 
ing a  curve  representing  the  rise  due  to  this  in- 
flow, all  the  water  being  stored  (see  Plate  XIX, 
Appendix  III). 

By  taking  the  difference  between  the  curve 
representing  the  lake  fluctuation  and  the  curve 
representing  45,940  second-feet  at  any  date,  as 


REPORT   OF  THE  COMMISSION 


23 


for  example  on  July  14,  and  plotting  this  diflfer- 
ence,  the  result  will  represent  the  fluctuation  of 
the  lake  under  the  physical  conditions  as  they 
existed  between  July  14  and  the  end  of  the 
record.  Had  the  sluices  remained  closed  be- 
tween January  1  and  Julv  14  the  lake  would 
have  risen  to  107,  and  if  then  thrown  fully 
open  the  lake  would  have  risen  only  one  inch 
higher  during  the  entire  season.  Had  they 
been  entirely  closed  again  on  October  28,  the 
lake  would  have  gained  two  feet  more  in  storage 
preparatory  to  the  next  dry  season,  which  it 
would  have  entered  at  108.68.  By  closing 
earlier  more  water  could  have  been  stored.  This 
matter  could  readily  be  regulated  by  the  judg- 
ment of  the  manager,  who  would  doubtless  have 
closed  the  valves  throughout  the  dry  season  and 
thus  have  stored  the  entire  outflow  during  that 
time. 

Location  of  Spillways. 

An  important  matter  in  connection  with  the 
regulation  of  the  lake  level  is  the  location  of  the 
regulating  works  or  spillway.  It  is  seen  that 
the  lake  may  at  times  have  to  discharge  as  much 
as  50,000  cubic  feet  per  second.  An  ideal  ar- 
rangement would  be  to  have  the  spillway  en- 
tirely independent  and  separated  from  the  canal 
proper  or  canalized  river.  A  careful  search  has 
been  made  for  such  location  on  the  west  side 
between  the  lake  and  the  Pacific,  but  no  suitable 
place  could  be  found  that  did  not  involve  an 
expense  almost  as  great  as  the-  constniction  of 
the  western  division  of  the  canal  itself.  It  has 
therefore  been  suggested  that  this  surplus  water 
might  be  discharged  through  the  canal  itself  as 
far  as  Buen  Retire,  and  there  turned  into  the 
valley  of  the  Rio  Grande,  which  it  would  be 
forced  to  follow  on  its  way  to  the  sea.  This 
plan  is  objectionable  for  several  reasons. 

It  will  necessitate  a  widening  of  the  canal 


proper  from  the  lake  to  Buen  Retiro,  a  dis- 
tance of  about  nine  miles,  the  most  of  which 
will  be  excavation  in  rock.  This  part  is  the 
Divide  cut  of  the  western  division.  Even  if  this 
cut  be  made  reasonably  wide,  the  current 
through  it  will  be  swift.  .  Of  course  the  greater 
the  width  the  less  the  current,  but  it  may  be 
questioned  whether  a  current  of  five  feet  a  sec- 
ond in  a  canal  200  feet  wide  would  be  entirely 
satisfactory  to  navigation.  Moreover,  200  feet 
width  will  only  discharge  about  35,000  cubic 
feet  per  second  with  a  five-foot  current,  and 
there  may  be  times  when  the  discharge  ought  to 
run  as  high  as  50,000  cubic  feet  per  second.  To 
carrv  this  amount  of  water  with  a  five-foot 
cuiTcnt  would  require  a  width  of  about  300 
feet. 

A  further  objection  would  be  the  difficulty 
of  properly  controlling  these  discharged  waters 
after  they  had  left  the  canal.  The  discharge 
of  35,000  to  50,000  cubic  feet  of  water  per 
second  into  the  vallev  of  tlie  Rio  Grande,  means 
the  creation  of  a  torrential  river  ten  times  the 
magnitude  of  the  existing  river  in  its  highest 
floods.  This  might  not  be  an  insuperable  ob- 
jection if  the  valley  of  the  river  were  rock  or 
some  material  not  easily  eroded.  The  soil  of 
this  valley  is  for  the  most  part  light,  sandy  and 
easily  put  in  motion  by  swift-running  water. 
The  distance  from  Buen  Retiro  to  the  Pacific 
is  about  eight  miles,  and  the  river  in  that  dis- 
tance would  have  a  fall  of  about  80  feet  from 
the  foot  of  the  spillway.  Moreover,  the  canal 
itself  will  be  located  in  this  valley,  and  at  the 
gorge  the  width  is  reduced  to  2000  feet.  A 
stream  like  the  one  thus  created  might  endanger 
the  canal  itself.  The  difliculties  of  controlling 
it  would  1)0  groat,  and  a  large  amoimt  of  the 
matorial  would  bo  sc»oured  and  carried  to  the 
ocean,   perhaps   to   the  groat  detriment  of  the 


24 


NICARAGUA  CANAL  COMMISSION 


entrance  to  the  canal.  It  is  possible  that  from 
10,000  to  15,000  cubic  feet  of  water  per  second 
might  be  discharged  througli  the  canal  on  the 
west  side  and  into  the  Rio  Grande  river  if  wid- 
ened and  straightened  without  damage,  but  the 
discharge  of  two  or  three  times  that  amoimt  is 
believed  to  be  impracticable  except  at  imwar- 
ranted  expense. 

Xor  does  there  appear  to  be  any  absolute  ne- 
cessity for  discharging  all  the  surplus  water  of 
the  lake  on  the  west  side.  The  San  Juan  river 
is  to-day,  and  has  been,  its  natural  and  only 
avenue  of  discharge.  According  to  the  esti- 
mates of  the  geologist  and  the  hydrographer, 
its  discharge  in  high  stages  has  at  times  been  as 
much  as  50,000  cubic  feet  per  second.  The 
evidence  appears  to  be  conclusive  that  even  this 
great  discharge  does  not  erode  its  banks  to  such 
a  degree  as  to  carry  much  sediment.  The  Agua 
Muerta  below  the  Machuca  rapids  indicates 
that  no  great  amoimt  of  sediment  is  carried  in 
the  upper  San  Juan,  and  this  notwithstanding 
the  fact  that  the  currents  have  been  greater  than 
thev  would  be  under  the  new  condition  of  affairs 
created  bv  the  canalization  of  the  river.  The 
fact  that  the  small  tributaries  that  drain  into  the 
San  Juan  may  at  times  discharge  as  much  as 
50,000  cubic  feet  per  second  between  the  lake 
and  the  San  Carlos  river,  is  objectionable,  but 
such  discharges  come  at  rare  intervals  and  last 
but  a  short  time.  Even  if  the  regulating  works 
could  not  take  care  of  it,  the  onlv  effect  w^ould 
be  to  raise  the  water  in  the  river  and  stop  the 
discharge  from  the  lake  for  a  short  period,  or 
possibly  turn  the  current  towards  the  lake.  If, 
then,  the  San  Juan  river,  discharging  sometimes 
as  much  as  50,000  cubic  feet  per  second,  in  ad- 
dition to  that  of  its  own  drainage  basin,  as  it 
exists  to-dav,  with  a  fall  from  the  lake  to  the 
foot  of  Machuca  rapids  of  48   feet,  does  not 


seriously  erode  its  banks,  it  does  not  seem  rea- 
sonable to  expect  more  erosion  when  that  fall  is 
reduced  and  the  discharge  area  of  the  river  in- 
creased. 

The  Commission  has,  therefore,  concluded 
that  the  discharge  from  the  lake  through  the 
canal  and  down  the  Rio  Grande  river  on  the  west 
side,  should  not  exceed  about  15,000  cubic  feet 
per  second,  and  that  the  remainder  should  be 
discharged  through  the  San  Juan  river.  The 
principal  regulating  works  are  therefore  de- 
signed to  be  located  at  the  site  of  the  dam  near 
Boca  San  Carlos,  capable  of  a  maximum  dis- 
charge of  S5,000  cubic  feet  per  second,  while 
the  works  on  the  west  side  should  have  a  ca- 
pacity of  20,000  cubic  feet. 

Projects  and  Routes. 

The  region  within  which  a  canal  can  be  con- 
structed is  comprised  within  comparatively  nar- 
row^ limits.  By  the  term  '*  Nicaragua  Route  ''" 
is  imderstood  a  canal  route  which  uses  Lake 
Nicaragua  as  a  part  of  its  system.  For  conveni- 
ence this  mav  be  divided  into  three  divisions: 

First,  the  division  between  the  Pacific  and 
the  lake,  called  the  western  division ; 

Second,  the  lake  itself; 

Third,  the  division  between  the  lake  and  the 
Caribbean  sea,  called  the  eastern  division. 

Western  Division. 

Col.  Childs,  an  eminent  civil  engineer,  in 
1850-51,  surveyed  and  located  a  route  for  a  canal 
over  this  western  division.  His  route,  starting 
from  the  Pacific  ocean  and  going  eastward,  from 
Brito,  at  the  mouth  of  the  Rio  Grande,  fol- 
lowed the  valley  of  this  river  to  a  point  about 
eleven  miles  from  the  lake,  thence  across  the  Di- 
vide to  the  valley  of  the  Lajas,  which  it  followed 
to   the  lake.     There    was   no   harbor  at   Brito^ 


REPORT  OF  THE  COMMISSION 


25 


and  he  proposed  to  form  one  by  the  construction 
of  jetties  and  by  excavating  the  alluvium  of 
which  the  coastal  plain  is  composed.  A  detailed 
description  of  the  project  is  given  in  the  report 
of  the  Board  of  1895. 

In  1873  a  survey  was  made  by  Commander 
Lull  of  the  TJ.  S.  Xavy.  He  proposed  to  con- 
struct a  harbor  at  Brito  and  to  follow  the  route 
suggested  by  Col.  Childs  up  the  valley  of  the 
Rio  Grande,  but  to  cross  the  Divide  farther  to 
the  north  and  to  follow  the  valley  of  the  Medio 
to  the  lake.  This  line  was  somewhat  shorter 
than  the  other,  but  involved  heavier  cutting  in 
the  Divide.  A  full  description  of  this  route  is 
given  in  Commander  Lull's  report. 

Mr.  Menocal,  the  Chief  Engineer  of  the  Mari- 
time Canal  Company,  after  furtlier  surveys, 
proposed  to  abandon  the  Medio  route  on  account 
of  the  heavy  cutting  in  the  Divide  and  adopted 
practically  the  route  suggested  by  Col.  Childs. 
His  first  project  was  for  a  canal  in  excavation 
along  the  north  side  of  the  valley  of  the  Rio 
Grande.  Subsequently  he  suggested  a  modi- 
fication of  this  project,  which  was  adopted  by 
the  Maritime  Canal  Company,  of  building  a  dam 
at  La  Flor  and  creating  an  artificial  basin  6.25 
square  miles  in  area,  reaching  from  near  the 
westerlv  side  of  the  Divide  to  w^ithin  four  miles 
of  the  Pacific  ocean.  At  the  projKJsed  site  of 
the  dam  the  vallev  of  the  Rio  Grande  narrows 
to  about  2000  feet,  and  the  surface  indications 
of  the  adjacent  hills  seemed  to  promise  good 
foundations  for  a  dam.  The  construction  of 
this  dam  would  practically  extend  the  lake  level 
westward  to  within  four  miles  of  the  Pacific 
ocean.  From  the  basin  thus  created  the  Pa- 
cific ocean  was  reached  bv  a  canal  with  three 
locks. 

The  Board  of  1S95  suggested  still  another 
project  for  a  canal  across  this  western  division 


which  did  not  differ  in  location  materially  from 
that  at  first  proposed  by  Col.  Childs,  but  fol- 
lowed the  left  bank  of  the  Rio  Grande  instead 
of  the  right.  These  several  routes  are  shown 
on  the  map  accompanying  this  report  and  a  fur- 
ther description  of  them  seems  imnecessary,  as 
full  descriptions  are  to  be  found  in  the  various 
reports  and  Congressional  documents  published 
bv  the  U.  S.  Government  from  time  to  time. 

The  relative  advantages  and  disadvantages  of 
these  several  routes  will  now  be  considered,  but 
solely  on  a  physical  basis  without  reference  to 
relative  cost. 

The  ^fenocal  project  of  creating  a  basin  in  the 
vallev  of  the  Rio  Grande  by  the  construction  of 
a  dam  at  La  Flor  has  the  advantage  of  bringing 
the  lake  level  close  to  the  Pacific  ocean.  The 
deep  part  of  such  a  basin  could  be  more  rapidly 
and  conveniently  navigated  than  a  qanal  in  ex- 
cavation. Moreover,  the  flood  discharges  of  the 
Tola  and  Rio  Grande  could  be  admitted  into 
the  basin  without  materially  affecting  the  sur- 
face level,  and  it  avoided  all  necessity  for  divert- 
ing the  waters  of  these  streams  from  the  canal 
eastward  of  the  dam. 

The  disadvantages  of  this  plan  are,  first,  the 
La  Flor  dam  itself.  Its  crest  would  have  to  be 
about  120  feet  above  sea  level,  allowing  10  feet 
for  freeboard,  while  the  solid  rock  is  found  at 
about  45  feet  below  sea  level.  The  total  height 
of  the  dam  in  the  deepest  part  would,  therefore, 
be  not  less  than  105  feet. 

Second.  If  a  high  dam  be  built  at  La  Flor 
to  hold  the  leve\  of  the  basin  at  110  feet  above 
sea  level,  all  the  locks  will  have  to  be  placed  on 
the  west  side  of  the  Rio  Grande.  This  is  a  dis- 
advantage because  the  area  suitable  is  limited. 

The  l(K'ks  will  necessarily  be  of  high  lift  and 
located  on  the  slope  of  the  hills  close  to  each 
other,  where  there  is  little  room  for  additional 


26 


NICARAGUA  CANAL  COMMISSION 


locks  sRould  they  become  necessary  by  future 
developments  in  the  commerce  through  the 
canal.  Moreover,  a  part  of  the  canal  itself  will 
necessarily  be  built  with  heavy  embankments  or 
retaining  walls  on  the  slope  of  these  hills,  and 
the  lower  Rio  Grande  will  either  have  to  be 
crossed,  taken  into  the  canal,  or  discharged  to 
the  eastward  of  the  proposed  harbor. 

Third.  The  creation  of  this  basin  would  sub- 
merge many  acres  of  land,  not  at  present  of 
great  value,  but  which  would  become  valuable 
should  a  canal  be  built. 

A  canal  in  excavation,  whether  it  follows  the 
right  or  left  bank  of  the  Rio  Grande,  avoids  the 
construction  of  the  La  Flor  dam,  presents  no 
special  engineering  difficulties,  enables  good  sites 
for  locks  to  be  selected,  and  preserves  for  culti- 
vation the  fertile  land  bordering  immediately  on 
its  banks.  Of  the  two  routes  in  excavation  the 
one  on  the  east  side  allows  the  river  to  discharge 
through  its  natural  mouth  on  the  west  side  of 
the  proposed  harbor.  It  is  somewhat  shorter 
than  the  other,  but  the  most  important  advan- 
tage is  that  it  enables  the  harbor  at  Brito  to  be 
constructed  on  the  east  side  of  the  Rio  Grande, 
which  is  considered  advisable  since  it  is  con- 
templated to  discharge  a  part  of  the  water  of 
the  lake  on  the  west  side  for  regulation  of  lake 
level. 

The  Menocal  project  could,  however,  be 
varied  by  providing  a  lock  and  dam  at  or  near 
Buen  Retiro,  and  dropping  down  to  a  lower 
level.  The  basin  would  in  this  case  be  diminished 
in  size,  and  the  dam  would  be  lowered  in  height 
by  the  number  of  feet  lift  in  the  lock.  Less  land 
would  be  submerged,  but  the  basin  would  not 
be  as  deep  nor  as  long.  On  the  other  hand, 
fewer  difficulties  would  be  encountered  in  con- 
structing the  locks  from  the  La  Flor  dam  to  the 
Pacific,  and  the  canal  could  be  carried  down  to 


the  sea  on  either  side  of  the  river  with  less  diffi- 
cultv. 

The  Commission  is  of  the  opinion,  in  view  of 
all  the  circumstances,  that  the  best  location  is  on 
the  left  bank  or  east  side  of  the  Rio  Grande. 

Lake  Division. 

The  lake  division  will  be  the  same  for  any 
project. 

Eastern  Division. 

The  projects  that  have  been  proposed  and  con- 
sidered for  the  eastern  division  admit  of  more 
variants  than  those  on  the  western  division,  but 
all  projects  for  the  eastern  division  look  to  canal- 
izing the  San  Juan  river  by  means  of  locks  and 
dams,  from  the  lake  to  the  vicinity  of  the  mouth 
of  the  San  Carlos  river. 

Three  projects  with  their  variants  are  all  that 
need  be  considered  on  the  eastern  side. 

The  first  is  that  for  canalizing  the  San  Juan 
river  from  its  source  at  the  lake  to  the  sea.  So 
far  as  the  canalization  of  the  river  from  the  lake 
to  Boca  San  Carlos  is  concerned,  no  doubt  exists 
as  to  its  practicability.  But  for  that  portion  of 
the  river  from  thence  to  its  mouth,  it  is  not 
deemed  practicable,  because  of  the  difficulties  of 
securing  good  foundations  for  dams,  the  torren- 
tial discharge  of  the  San  Carlos  and  Sarapiqui 
rivers  and  the  great  quantities  of  sand  carried  by 
them  and  deposited  along  the  river  channel  of 
the  lower  San  Juan. 

A  second  project  is  that  suggested  by  Mr. 
Menocal,  which  had  for  its  object  the  extension 
of  the  lake  level  through  the  "  Divide  cut ''  to 
within  twelve  miles  of  Grey  town.  It  is  similar 
to  that  suggested  by  him  for  the  west  side.  It 
looked  to  the  construction  of  a  high  dam  at 
Ochoa,  a  short  distance  below  the  mouth  of  the 
San  Carlos  river,  by  means  of  which  the  waters 
of  the  San  Juan  were  to  be  raised  to  the  level 


REPORT   OF  THE   COMMISSION 


27 


of  the  lake.  From  the  south  end  of  this  dam 
embankments  were  to  be  built  in  the  saddles 
of  the  San  Carlos  ridge,  to  connect  with  the 
tills  in  Costa  Rica,  thus  cutting  off  the  escape 
of  the  raised  waters  of  the  San  Juan  on  that 
side.  In  this  embankment  line  sluices  were  to 
be  built  to  discharge  the  surplus  waters  of 
the  lake  which  find  their  way  down  to  the  San 
Juan  river,  as  well  as  the  floods  of  the  San 
Carlos  itself. 

From  the  north  end  of  the  Ochoa  dam  similar 
embankments  were  to  be  built  across  the  saddles 
in  the  hills  on  this  side,  until  connection  was 
made  mth  the  high  ridge  known'  as  the 
"^^  Divide."  This  was  known  as  the  San  Fran- 
cisco embankment  line,  and  it  crossed  the  rivers 
San  Francisco,  Danta  and  Chanchos.  The  num- 
ber of  dams,  large  and  small,  was  67,  those  across 
the  rivers  named  being  the  largest.  This  em- 
bankment line  had  a  length  of  about  15i  miles 
from  the  north  end  of  the  Ochoa  dam  to  the  Di- 
vide, of  which  six  miles  were  artificial.  Sluices 
were  to  be  built  at  convenient  places  along  this 
embankment  to  discharge  the  surplus  waters  of 
the  drainage  area  to  the  northward. 

By  means  of  the  Ochoa  dam  and  the  San 
F'rancisco  and  San  Carlos  embankments  a  large 
pool  or  basin  of  irregular  shape  was  to  be  created 
and  the  surface  of  the  water  maintained  at  or 
near  the  level  of  that  in  the  lake  itself.  The 
excavation  in  the  upper  river  and  in  the  pool  was 
thus  reduced  to  a  minimum. 

From  a  point  near  the  eastern  end  of  the 
Ochoa  dam  the  canal  was  carried  in  excavation  to 
the  valley  of  the  Danta,  or  Florida  lagoon,  and 
from  thence  in  pools  and  cuts  to  the  valley  of  the 
Limpio  which  it  followed  to  the  Divide  cut. 
This  cut  is  about  three  miles  long  and  has  an 
average  depth  of  134.4  feet,  the  maximum  depth 
being    about    350    feet.     After    crossing    the 


Divide  the  canal  descends,  by  means  of  three 
locks  of  high  lift,  into  the  valley  of  the  Deseado 
which  it  follows  to  the  coastal  plain,  after  reach- 
ing which  it  continues  in  a  nearly  direct  line  to 
Greytown. 

A  third  project  is  to  construct  a  dam  in  the 
San  Juan  river  just  above  the  mouth  of  the  San 
Carlos,  giving  slack  water  navigation  from  the 
lake  to  the  dam,  and  thence  by  a  canal  in  excava- 
tion along  the  left  bank  of  the  San  Juan  or  near 
it,  to  the  junction  of  the  San  Juan  with  the  San 
Juanillo,  and  from  thence  across  the  coastal 
plain  to  Greytown. 

Each  of  the  two  latter  projects  admits  of  vari- 
ants. The  Menocal  project  can  be  varied  by 
locating  the  dam  across  the  San  Juan  above  the 
mouth  of  the  San  Carlos  river,  starting  with  ex- 
cavation to  the  eastward  of  that  dam  and  thence 
following  a  route  substantially  as  projected  by 
Mr.  Menocal  himself.  Or,  a  lock  may  be  used 
in  connection  with  this  dam  and  the  height  of 
the  embankments  be  correspondingly  reduced. 
This  would  increase  the  depth  of  the  Divide  cut 
by  the  same  amount.  The  practicability  of  a 
dam  only  a  short  distance  above  the  mouth  of 
the  San  Carlos  river  has  heretofore  been  doubt- 
ed, but  the  surveys  show  that  such  a  dam  is  not 
only  practicable  but  will  be  easier  of  construction 
than  one  at  Ochoa. 

Another  variant  would  be  to  build  a  dam  near 
the  lower  Machuca  rapids  and  lock  down  24  to 
30  feet,  then  follow  the  rest  of  the  route  practi- 
cally as  laid  down  l)y  Mr.  Menocal,  the  object  of 
the  latter  variant  being  to  avoid  the  constniction 
of  a  high  dam  at  Ochoa  and  to  reduce  the  height 
of  the  San  Francisco  and  San  Carlos  embank- 
ment lines.  This  would  increase  the  depth  of 
the  Divide  cut. 

Another  variant  would  be  to  construct  a  dam 
at  Tambor  Grande  and  an  embankment  on  the 


28 


NICARAGUA  CANAL  COMMISSION 


south  side  connecting  with  the  hills  in  Costa 
Rica.  This  would  take  the  place  of  the  Ochoa 
dam  and  eliminate  the  San  Francisco  and  San 
Carlos  embankments.  This  is  regarded  as  im- 
practicable. 

Other  variants,  such  as  increasing  the  number 
of  locks  or  varying  their  location,  suggest  them- 
selves. 

The  third  project  can  be  varied  by  construct- 
ing one  or  more  dams  with  locks  in  the  upper 
river,  thus  reducing  the  height  of  the  dam  at 
San  Carlos.  Or,  after  reaching  the  junction  of 
the  San  Juan  with  the  San  Juanillo  any  one  of 
several  routes  may  be  taken  to  the  sea. 

ifr.  MenocaPs  project  has  an  advantage  in 
that  it  is  two  miles  shorter  than  the  other  project 
following  the  bank  of  the  river.' 

Its  disadvantages  are,  first,  the  engineering 
difficulties  encountered  in  building  the  Ochoa 
dam.  This  dam  being  located  but  a  short  dis- 
tance below  the  mouth  of  the  San  Carlos  river, 
its  construction  would  be  attended  with  no  little 
risk. 

Second,  the  San  Francisco  embankment  line 
is  another  troublesome  engineering  construction. 
This  embankment  follows  an  irregular  line  from 
Ochoa  to  the  Divide.  Xo  less  than  67  dams  will 
be  required,  some  of  them  insignificant  in  size, 
but  four  of  them  of  great  length  and  of  more 
than  ordinary  difficulty  to  build  and  maintain, 
because  of  their  great  height  and  the  pressure 
of  water  to  which  they  would  be  subjected,  as 
well  as  to  the  fact  that  the  soil  on  which  they 
would  have  to  be  founded  is  overlain  for  a  great 
depth  with  soft  ooze. 

A  third  disadvantage  is  the  Divide  cut  itself. 
This,  as  before  stated,  is  over  three  miles  long. 
In  addition,  it  is  curved,  the  curvature  being  in 


1  Comparison  of  distances  between  the  lake  and  Grey  town 
harbor. 


places  the  maximum  that  should  be  allowed  in  a 
canal  of  this  magnitude.  This  would  render 
navigation  difficult.  Its  great  depth  would  also 
be  a  constant  menace,  for  while  it  is  believed 
that  the  rock  for  the  most  part  would  stand, 
there  is  some  likely  to  cause  trouble.  A  large 
portion  of  it,  dacite,  a  rock  that  weathers  rapidly, 
is  of  light  specific  gravity,  and  not  to  be  trusted 
in  a  deep  cut  like  that  through  the  Divide. 
Again,  on  account  of  its  depth  and  length  it 
would  necessarilv  be  made  of  the  minimum 
width  practicable  for  navigation;  consequently 
if  the  canal  were  working  to  its  full  capacity 
there  would  inevitably  be  some  delay  to  vessels 
passing  through  it,  since  two  large  ships  could 
not  paas  each  other..  Vessels  would  therefore 
accumulate  at  either  end  to  be  passed  at  stated 
intervals  in  fleets. 

The  variant  providing  for  the  constniction 
of  a  lock  and  dam  at  Machuca,  locking  down 
say  24  feet,  would  reduce  the  height  of  the  San 
Francisco  embankments  and  the  Ochoa  dam; 
but  the  excavation  in  the  San  Juan  river  and 
eastward  to  the  eastern  end  of  the  Divide  cut 
would  be  increased  by  this  extra  depth.  There 
would  still  be  the  Ochoa  dam,  though  of  less 
height,  to  be  constructed  in  contention  with  the 
floods  of  the  combined  San  Juan  and  San 
Carlos  rivers.  If  the  dam  be  built  above  the 
mouth  of  the  San  Carlos  river  instead  of  below 
it  at  Ochoa,  there  would  yet  remain  the  objec- 
tionable San  Francisco  embankments  and  the 
Divide  cut. 

The  project  which  looks  to  the  construction  of 
a  dam  above  the  mouth  of  the  San  Carlos  river, 
and  follows  close  to  the  north  bank  of  the  San 
Juan  river  as  far  as  the  junction  of  the  San  Juan 
and  San  Juanillo,  has  the  disadvantage  of  an 
increase  in  length  of  about  two  milet?,'  but  on 
the  other  hand  it  is  believed  the  difficulties  of 


REPORT   OP  THE  COMMISSION 


29 


construction  will  be  lessened  because  of  the  re- 
duction in  the  height  of  the  embankments  and 
by  avoiding  the  Divide  cut. 

There  are,  nevertheless,  several  hills  of  con- 
siderable height  to  be  cut  through  on  this  route. 
The  Tamborcito  hill  will  require  a  maximum 
depth  of  230  feet  of  cutting  in  rock,  but  it  is  less 
than  a  half  mile  in  length,  and  the  material  will 
be  required  on  the  work,  while  an  attempt  to  cir- 
cumvent the  hills  mav  involve  an  embankment 
founded  upon  a  depth  of  80  feet  or  more  of 
black  sand  in  the  bed  of  the  river.  From  this 
point  to  Lock  Xo.  1  most  of  the  canal  tnmk 
will  be  enclosed  between  embankments  built 
of  the  silt  from  the  excavations.  In  short  dis- 
tances they  may  exceed  30  feet  in  height,  with 
a  pressure  of  twenty  feet  of  water. 

A  variant  on  this  project  will  be  in  the  con- 
struction of  two  dams  in  the  river  al)ove  the  one 
near  the  mouth  of  the  San  Carlos.  But  it  has 
no  advantage  over  the  other  except  that  it 
enables  the  Iriwer  dam  to  be  reduced  in  height. 
This  is  not  considered  of  great  importance,  for 
while  the  construction  would  be  easier,  the  main 
difficulty  would  be  in  the  foimdations  and  they 
would  not  be  materiallv  different.  It  has  several 
serious  disadvantages,  however,  in  obstructing 
the  passage  of  large  volumes  of  water  at  narrow 
sections  of  the  river  and  in  confining  the  navi- 
gation below  the  upper  dam  to  a  narrow  channel 
excavated  in  large  part  through  rock. 

Numerous  other  adjustments  in  detail  ninv  be 
made,  both  in  the  alignment  and  grade,  but  they 
an*  not  of  sufficient  importance  to  warrant  con- 
sideration prior  to  final  location. 

Gkevtowx  Hakiku:. 

A  suitable  harbor  with  a  safe  entrance,  at  the 
oast(»rn  end  of  the  canal,  is  an  essential  rinpiisite 
to  its  proper  operation.      Xo  such  harbor  now 


exists.  About  fifty  years  ago  there  was  a  good 
harbor  at  Grey  town  with  thirty  feet  of  water  in 
the  anchorage  and  at  the  entrance.  The  sand, 
however,  that  has  been  brought  down  by  the 
San  Juan  river  and  deposited  in  the  sea  has 
closed  the  entrance,  and  in  a  large  measure  filled 
up  the  harbor  itself.  This  sand  movement  has 
been  .going  on  for  ages,  as  the  numerous  lagoons 
that  have  been  formed  parallel  to  the  coast 
line  testify.  The  sand  has  been  ejected  from 
volcanoes  in  the  region  of  the  headwaters  of  the 
Costa  Rican  tributaries  of  the  San  Juan,  car- 
ried down  to  the  sea  by  the  river,  deposited  on 
the  ocean  bed,  and  then  transported  by  wave  ac- 
tion in  one  direction  or  the  other  according  to 
the  prevailing  winds  and  the  resulting  direction 
of  the  waves. 

By  the  term  **  harbor ''  it  is  not  intended  to 
convey  the  idea  that  a  large  harbor  should  be 
constructed  for  commercial  purposes.  A  harbor 
of  sufficient  area  to  accommodate  the  vessels 
that  arrive  for  the  purpose  of  passing  through 
the  canal  is  all  that  is  considered  necessarv.  It 
is  not  expected  that  vessels  will  lie  in  such  a 
harbor  for  any  length  of  time,  but  will  move 
through,  either  in  one  direction  or  the  other. 

For  canal  construction  purposes  a  harbor  is 
necessary.  One  of  the  first  things,  therefore,  to 
be  done  in  undertaking  the  construction  of  the 
canal  will  be  to  form  a  harbor  of  reasonable 
depth.  This  has  an  important  bearing  in  esti- 
mating the  cost  of  construction. 

The  San  Juan  river  drains  a  basin  of  about 
17,000  square  miles.  The  silt  d(»posited  in  its 
delta  during  past  ages  has  built  out  the  coast, 
with  characteristic  lagoons  and  extensive  marshes 
covering  the  broad  plain  between  the  ])r(*sent 
shore  linc^  and  the  original  foot-hills  of  the  (.V»r- 
dilleras. 

The  delta   may   be  said  to  begin  at  a  point 


30 


NICARAGUA   CANAL  COMMISSION 


twelve  miles  in  an  air-line  from  the  outer  coast, 
where  the  San  Juanillo  leaves  the  main  trunk. 
This  stream  has  been  turned  parallel  to  the  coast, 
and  finally  reunites,  through  a  series  of  lagoons, 
with  the  lower  San  Juan.  The  latter  is  flanked 
by  lagoons  indicative  of  original  beaches,  the 
three  to  the  north  being  typical  of  the  prevailing 
direction  of  the  drift  on  this  portion  of  the  coast, 
due  to  the  angle  of  wave  incidence.  These  la- 
goons are  nearly  parallel  to  the  existing  coast 
line  and  are  separated  by  strips  of  land  enclosing 
long,  narrow  lakes.  The  date  of  these  forma- 
tions is  not  ascertainable  from  any  existing 
records. 

It  woidd  seem  that  what  is  now  the  lower 
San  Juan  river  was  at  one  time  the  main  stream 
and  discharged  most  of  the  sediment,  the  waves 
produced  by  the  trade  winds  carrying  a  part  of 
the  material  to  the  westward  and  a  part  of  it  to 
the  southward,  the  westerly  movement  of  this 
sand  having  formed  lagoons  whose  longer  axes 
are  nearly  parallel  to  the  coast.  The  prevailing 
winds  are  from  the  northeastward  and  while  they 
rarely  blow  with  great  violence,  they  blow 
steadily  and  with  considerable  force,  creating  a 
sea  which  stirs  up  the  light  sand  of  which  the 
beach  is  composed  and  carries  it  along  in  great 
volume.  One  has  only  to  observe  the  waves 
charged  with  black  sand,  running  diagonally 
along  the  beach,  to  realize  their  potent  agency 
in  transporting  this  material. 

The  Board  of  1895  gives  a  very  complete  de- 
scription of  the  sand  movement  on  this  coast,  a 
full  discussion  showing  how  the  destruction  of 
Grey  town  harbor  as  it  formerly  existed  was 
brought  about,  and  the  steps  necessary  to  be 
taken  in  the  construction  of  a  new  harbor.  The 
conclusions  arrived  at  by  that  Board  were  that 
.  the  Maritime  Canal  Company's  proposed  en- 
trance is  inadmissible,  and  the  Harbor  Head  en- 


trance inexpedient,  and  that  the  best  results  will 
be  obtained  by  locating  the  entrance  approxi- 
mately half-way  between  the  two.  This  Com- 
mission is  of  opinion  that  equally  good  results^ 
at  less  cost,  can  be  obtained  by  a  change  in  the 
entrance  and  form  of  the  harbor  itself.  The 
Commission  has,  therefore,  located  the  east  jetty 
about  2000  feet  westward  of  the  position  sug- 
gested by  the  Board  of  1895,  the  harbor  itself 
to  be  about  5000  feet  long  by  1000  feet  wide„ 
and  the  entrance  between  the  jetties  to  be  60O 
feet. 

The  construction  of  a  jetty  across  the  path  of 
moving  sand  must  of  necessity  cause  accumula- 
tions of  drift  to  windward,  hence  the  angle 
formed  between  any  such  projecting  structure 
and  the  shore  must  gradually  fill  up  and  the 
shore  line  advance  seaward  until  the  capacity  of 
this  receptacle  is  exhausted.  This  advance  di- 
minishes as  the  depth  and  consequent  capacity 
of  the  pocket  increase,  but  it  shows  that  some 
expense  must  be  incurred  for  the  maintenance 
of  the  harbor  either  by  jetty  extension  or  by 
the  removal  of  the  material  from  time  to  time,, 
which  would  otherwise  find  its  wav  around  the 
end  of  the  jetty  and  into  the  channel.  A  study 
has  therefore  been  made  of  the  various  surveys 
of  the  harbor  with  a  view  to  determining  the 
probable  amount  of  material  to  be  controlled  in 
the  maintenance  of  the  entrance.  This  amount 
is  estimated  to  vary  from  500,000  to  730,000 
cubic  yards  annually. 

The  entrance  to  the  harbor  will  be  formed 
by  two  parallel  jetties  about  600  feet  apart,  the 
easterly  one  about  20 70  feet  in  length,  the 
westerly  one  2500  feet.  They  will  extend  sea- 
ward in  a  northerly  direction,  thus  giving  shelter 
from  the  sea,  which  comes  generally  from  the 
northeastward.  As  the  sea  strikes  the  shore 
line  with  considerable  violence  at  times,  these 


REPORT   OF   THE   COMMISSION 


31 


jetties  will  be  constnieted  chiefly  of  heavy  stones 
not  easily  moved  by  the  force  of  the  waves.  To 
obtain  suitable  stone  for  this  purpose  in  large 
quantities  and  with  the  utmost  dispatch,  so  that 
a  part  at  least  of  the  jetty  can  be  quickly  con- 
structed, quarries  will  have  to  be  opened  at  the 
most  favorable  locations. 

Brito  Haebor. 

At  the  westerly  terminus  of  the  canal  there  is 
no  harbor.  The  nearest  harbor  is  that  at  San 
Juan  del  Sur,  about  eight  miles  to  the  south- 
eastward, but  this  cannot  be  put  to  any  useful 
purpose  so  far  as  the  canal  itself  is  concerned, 
though  it  may  be  utilized  in  a  measure  during 
the  early  stages  of  canal  construction.  A  har- 
bor will  have  to  be  constnieted  at  Brito  as  at 
GreytowTi.  San  Juan  del  Sur  could  only  be 
used  to  advantage  during  construction  by  the 
building  of  a  railroad  from  there  to  the  canal. 

The  remarks  as  to  the  capacity  of  a  harbor  at 
Greytown  will  apply  with  equal  force  to  Brito. 
In  other  words,  a  harbor  of  refuge  is  not  needed, 
but  only  such  a  harbor  as  will  make  the  canal 
available  for  commerce.  Vessels  will  seldom  go 
to  Brito  imless  entering  or  leaving  the  canal. 

The  conditions  on  this  coast  are  not  as  forbid- 
ding as  they  are  on  the  eastern.  The  sand  move- 
ment is  slight  and  the  winds  are  mostly  off  shore, 
consequently  the  difficulties  to  be  encountered 
will  be  more  easily  overcome.  The  mean  rise 
and  fall  of  tide  is  about  7  feet  The  sea  during 
the  greater  part  of  the  year  breaks  normal  to  the 
direction  of  the  shore;  the  prevailing  wind  is 
from  the  northeast,  and  while  west  and  south 
winds  sometimes  blow  tliev  are  of  rare  occur- 
rence. 

The  shore  is  bold,  and  deep  soundings  are 
found  at  no  great  distance  from  it.  The  shore 
line  trends  from  northwest  to  southeast,  but  the 


rocky  promontory  on  the  north  side  of  the  Kio 
Grande  projects  into  the  sea  and  gives  a  certain 
amount  of  protection. 

On  account  of  the  rapid  increase  in  depth 
from  shore  seaward,  an  outer  harbor  is  almost 
impracticable  within  the  limits  of  reasonable 
cost,  so  that  one  is  restricted  to  the  formation  of 
an  inland  harbor  within  the  area  that  is  now  oc- 
cupied by  a  swamp.  From  borings  made  and 
all  information  obtainable  it  is  believed  that  this 
material  is  easv  to  excavate.  In  fact  it  is  known 
that  some  of  the  borings  taken  by  the  Canal 
Company  in  close  proximity  to  the  proposed  har- 
bor, which  seemed  to  indicate  rock  at  no  great 
depth,  were  deceptive  and  that  the  boring  appa- 
ratus struck  boulders  which  were  supposed  to  be 
solid  rock. 

The  harbor  proposed  by  Col.  Childs  opened 
directly  to  the  south,  and  was  protected  by  two 
jetties,  one  springing  from  the  sandy  beach  and 
nmning  southward,  the  other,  but  smaller  jetty, 
springing  from  the  Brito  promontory  and  run- 
ning southeastward.  The  entrance  was  400  feet 
wide.  An  inner  harbor  was  formed  by  a  chtage 
in  direction  of  the  entrance  at  nearly  a  right 
angle,  which  gave  good  protection.  The  size 
and  depth  of  the  harbor  proposed  would  be  ut- 
terly inadequate  to  the  present  size  and  draft  of 
ships.  A  diversion  of  the  Rio  Grande  to  the 
eastward  of  the  entrance  was  a  necessary  feature 
of  this  scheme. 

Capt.  Lull,  in  his  project  for  a  harbor,  made 
some  changes  in  the  Childs  project,  with  a  view 
to  giving  a  wider  entrance  and  more  capacious 
and  deei)er  harbor,  suited  to  the  increased  depth 
which  he  proposed. 

The  Maritime  Canal  Company  also  proposed 
a  plan  for  a  harbor,  increasing  the  area  to  103 
acres. 

The  Board  of  1895  suggested  still  another 


32 


NICARAGl'A   CANAL  COMMIS.-I()N 


project,  the  main  feature  <»f  wliicli  was  the  ex- 
tension of  the  west  jetty  of  the  Lull  phm  to  u 
length  of  3C00  feet.  This  was,  liowevrr,  niily 
provisional,  with  a  view  to  an  appn)xiniati'  esti- 
mate and  not  as  a  definite  projeet  n(M*essarily  to 
be  followed.  That  Boanl  di-tinrtly  stated  that 
"the  information  avaihal>le  is  not  suHiricnt  to 
enalde  final  plans  and  estimates  to  h(»  ni:i«lf." 

All  the  plans  proposeil  liave  crrtain  inlim-nt 
defects,  and  it  is  scaively  possilih*  to  cnu^ti'iirt  a 
harbor  at  this  ])hu*e  that  will  he  ]MM'fect.  A 
bn^akwater  to  shelter  an  i*ntranr(»  becomes  a 
verv  exjKMisive  stnictnre  in  such  a  pla^e  as  Hrito 
and  is  liable  to  introduce  other  objectioual>lc 
features. 

It  is  believed,  however,  that  the  ditfirulties  of 
a  vessel's  enterin^r  between  two  jetties  that  pnv 
ject  seaward  in  the  direction  of  the  advancin<r 
waves  have  been  overestimated  in  tin-  case  un- 
der consideration.     San  Juan  del  Sur  is  a  fairlv 

« 

good  harbor,  yet  its  entrance  is  ojx-n  to  the  sea. 
It  is  said  that  no  trouble  is  experieneej]  by  ship- 
ping at  this  place  from  >\U'\\  exposure.  A  Va- 
eitie  Mail  steamer  calls  at  this  harbor  miee  a 
week  throughout  the  year.  She  does  not  g<>  to 
a  dock,  for  thei-e  is  nrnie  at  which  she  could  lie, 
but  it  is  understooil  no  trouble  i.-  experienced  in 
lightering  from  her  anchorage. 

To  pennit  a  vessel  to  ent»'r  the  harbor  normal 
to  the  swell,  and  at  the  sauH'  time  tti  guard  it 
against  agitation  from  the  adnli^^si^ul  of  largi- 
waves,  are  conditions  not  easily  ^atistied,  but  tin* 
Commission  believes  that  the  form  of  Imrbnr 
presented  with  this  reiMjrt  will  mei'i  tiie  con«li- 
tions  as  nearly  as  it  is  ju-acticable  to  do  within 
the  limits  of  reasonable  cost  and  in  a  maiiMer  le-s 
objectionable  than  any  other  yet  proj>oM'.|. 

The  plan  is  to  build  a  jetty  from  a  j joint  on 
the  beach  about  oGOO  feet  east  of  the  iJritn 
promontoiy,  extending  out  into  the  -ea  in  a  tli- 


rection  nearlv  >4)uth-sout Invent  to  the  seven- 
fatliom  <»urve:  tln*n  excavate  u  harbor  of  tbe 
t'nrm  shtrwn  on  the  plan,  to  the  eastward  oft 
north  an<l  -uMith  line  through  the  root  of  the 
iettv,  the  entnince  to  lie  iJOO  feet  wide  at  the 
thritat.  This  will  give  .sei-iirity  an<l  compara- 
tively .-still  water  in  all  winds  exoept  those  com- 
ing fn>ni  -onth  by  west  and  a  few  deprcres  either 
>ide.  Tin*  proniontory  will  prote«*t  from  winds 
comiiiir  fr«»m  a  nion'  wi'stiTlv  dirot'tion  and  the 
jetty  from  all  wind*^  coming'  froui  a  direction  east 
of  sonth.  The  ba.-in  to  lie  exc'avat4*<l  ha$  a  bot- 
tom area  of  iilMiut  l*»a  acres  and  a  depth  of  30 
feet  at  nu-an  li»w  tide  with  a  de|>th  of  36  at  the 
I  ntrance.  As  the  movement  <»f  san<l  Ls  slight 
the  co^t  of  maintenanc(»  will  not  1h*  ^cat. 

The  Kio  drand*'  in  this  project  will  not  be 
<liverti'd  at  its  lnwer  end,  btit  it  will  have  to  he 
enlarged  in  cross  section  in  order  to  carrv  in- 
i-reased  discharge. 

If  the  c«  nclusions  reaehe<l  l>y  this  Commi:^ 
>ion  that  thir-  harbor  gives  all  the  protection  that 
i<  ne<«h'd,  be  found  by  time  and  ex[)erience  to  W 
inci»rre«'t,  a  jettv  from  the  proinontorv  eastwanl 
«-an  beailded  at  any  future  tini€».  It  is  iKdieve^l, 
however,  that  such  jetty  will  never  he  requinJ, 
and  no  provision  has  bei'n  made  in  the  estimate 
for  one. 

1)a.MS    AM>    KMaANKMKS'TS. 

T«»  (Min^truct  <afe,  ilurable  and  stahle  stnic- 
tnre^ fnr  the  control  of  the  drainage  and  for 
navii!atiMn  i-  a  sinr  ifitu  lum. 

T\u'  jirincijKi!  .-auses  for  the  failures  of  dani-^ 
cir  rc-»  rvoirs  mny  be  traced  to  defective  founda- 
tions imjiropiT  di  >ign  or  imi>erfeet  construction, 
-ingle  or  ciinibined.  Probahly  the  most  frt- 
»iue!it  «mum-  of  their  failtirc;  are,  their  permea- 
biliiy  cjni>ing  a  breach  by  seepage,  and  their 
lack  I'f  -jjillway  capacity  allowing  the  dams  to 

in-    nV(  ll«i|ip<'il    hv    tlutnls. 


REPORT   OF  THE  COMMISSION 


33 


The  sites  projX)sed  in  Xicaragna  for  the  dams 
are  such  that,  in  connection  with  the  large  im- 
pounding capacity  of  the  lake  acting  as  a  reser- 
voir, there  is  little  or  no  danger  of  sudden  floods 
reaching  their  crests,  so  that  the  risk  from  this 
source  is  believed  to  be  eliminated  by  providing 
an  ample  waste-way  and  freeboard.  This  re- 
mark applies  with  still  greater  force  to  the  em- 
bankment lines,  which  may  be  used  for  the  pur- 
pose of  enclosing  large  artificial  lakes  in  basins 
of  limited  drainage  area  and  not  subject  to  the 
discharge  from  the  river. 

Moreover,  there  is  an  almndance  of  material 
suitable  for  puddle,  which  if  properly  applied 
will  secure  impenneability.  The  main  diffi- 
culty, therefore,  is  that  resulting  from  insecure 
foimdations.  For  the  dams  in  the  rivers  clos- 
ing the  summit  level,  satisfactory  rock  bottoms 
and  abutments  are  available,  but  to  reach  rock 
on  the  San  Francisco  embankment  line  is  a  morc 
difficult  and  expensive  problem. 

Dams  ox  the  Eastern  Division. 

In  view  of  the  large  amount  of  earth  and  rock 
excavation  and  the  necessity  for  disposing  of  the 
spoils,  it  was  decided  by  the  Maritime  Canal 
Company  to  construct  high  rock-fill  dams  on 
both  sides  of  the  lake  for  the  purpose  of  im- 
pounding the  waters  of  the  summit  level,  but 
the  desirability  of  avoiding  the  San  Carlos  river 
and  of  facilitating  the  construction  of  the  dam 
itself,  has  led  this  Commission  to  select  a  new 
and  better  site  a  short  distance  above  the  mouth 
of  the  San  Carlos  river. 

The  borings  made  on  the  site  of  the  proposed 
Ochoa  dam  revealed  rock  at  17  feet  below  sea 
level,  suitable  for  foundations.  The  width  be- 
tween banks  is  n^latively  nan*ow,  for  at  an  eleva- 
tion of  100  feet  above  sea  level  it  is  about  1400 
feet.     As  this  site  is  below  the  junction  ^f  the 

3 


San  Carlos  river,  which  at  flood  stages,  it  is  esti- 
mated, may  discharge  100,000  cubic  feet  per 
second  in  addition  to  the  lake  and  San  Juan 
river  drainage,  this  large  volume  must  either  be 
disposed  of  over  spillways  on  the  San  Carlos 
ridge  or  be  allowed  to  waste  over  the  dam  itself. 
It-s  sediment  also  would  l)e  deposited  in  the  bed 
of  the  stream  above  the  dam  and  cause  constant 
shoaling.  At  lower  Ochoa  the  sand  extends  to 
30  feet  below  sea  level.  To  avoid  these  serious 
objections  as  well  as  to  eliminate,  if  possible, 
the  embankments  of  the  San  Francisco  and 
Florida  lagoons,  examinations  were  made  for  a 
dam  site  at  Tambor  Grande  island.  The  subse- 
quent borings  in  the  bed  of  the  river  at  this  site, 
however,  showed  an  erosion  of  the  bed  rock  ex- 
tending to  128  feet  below  sea  level,  which  would 
necessitate  a  dam  in  this  narrow  gorge  of  the 
river  nearly  250  feet  in  height,  subject  to  the 
flow  of  the  entire  drainage  basin.  This  project 
was,  therefore,  discarded. 

The  more  recent  examinations  and  surveys, 
made  on  the  wider  reach  of  the  river  above  the 
San  Carlos,  gave  results  which  were  quite  satis- 
factor5\  Here  the  flowage  line  is  almost  con- 
tinuous, requiring  but  one  small  embankment, 
while  the  section  affords  ample  weir  length. 
Good  solid  rock  foundations  exist  at  about  15 
feet  below  sea  level.  Thus  the  maximum  height 
of  the  dam  from  the  bottom  of  the  foundation 
would  be  138  feet.  The  construction  of  a  dam 
at  this  point  avoids  the  serious  objections  to  the 
Ochoa  site,  and  also  reduces  the  cost  and  diffi- 
culties of  construction. 

The  estimates  are  based  upon  concrete,  which 
can  be  mixed  on  the  site.  Kegulating  works 
and  sluices  can  be  provided  in  the  original 
river  channel,  and  the  entire  length  of  the  crest 
may  be  utilizcnl  for  a  spillway  in  case  of  ne- 
cessitv. 


34 


NICARAGUA  CANAL  COMMISSION 


The  typical  section  on  which  the  estimates  are 
based  is  the  ogee  rising  from  the  natural  bed  of 
the  stream  at  an  elevation  of  about  38  feet  above 
sea  level  to  the  proposed  weir  sill  at  98,  with 
regulating  sluices  to  control  the  higher  stages. 
The  width  of  the  base  at  the  deepest  point  is  100 
feet.  The  ordinary  stage  of  water  at  the  foot 
of  the  dam  is  about  55  above  sea  level,  while  ex- 
treme low  water  is  about  45. 

Sites  for  Low  Dams. 

There  are  various  locations  on  the  river  where 
dams  may  safely  be  placed  for  variations  of  pro- 
ject. Taking  these  in  order,  coming  down 
stream,  the  first  mav  be  at  Castillo  where  the 
river  flows  over  ledges  of  basalt  which  is  some- 
what jointed,  giving  it  the  appearance  of  being 
stratified,  but  it  is  believed  to  be  firm  and  strong. 
The  anchorages  also  are  good. 

At  Upper  Machuca,  three  miles  above  Ma- 
chuca,  the  rock  is  calcareous  sandstone  with 
limited  weathering.  Solid  rock  is  usually  found 
under  a  few  feet  of  sand  in  the  river  channel, 
but  the  rock  in  the  adjacent  hills  is  weathered 
down  nearlv  to  the  same  level  as  the  surface  of 
the  solid  rock  in  the  channel  so  that  the  anchor- 
age must  be  in  residual  clay  and  soft  rock. 

Tlie  Macliuca  site  is  situated  across  the  head 
of  Campafia  island.  It  is  based  on  a  fine-grain- 
ed light-bluish  gray  rock,  evenly  bedded,  and 
closely  resembling  a  fine-grained  quartzite.  The 
borings  on  the  south  banks,  however,  show 
great  depths  of  weathering,  making  it  desir- 
able to  shift  the  location  farther  up  or  down 
stream. 

Conchuda  about  two  miles  above  the  Boca 
San  Carlos  also  affords  a  possible  dam  site  and 
has  been  considered  with  a  view  to  reduce  the 
large  amoimt  of  rock  excavation  incidental  to  the 
Machuca  dam  projects. 


Relative  Cost  of  the  Several  Oonoeete  Dam 

Projects  Between  the  Lake  and  Boca 

San  Carlos,  Including  the  Latter. 

These   estimates  are   based   upon    the   same 

prices  in  each  case  and  are  submitted  merely  as 
a  guide  to  the  relative  merits  of  the  plans: 

Low^  dam  at  Upjier  Machuca $1,045,569 

Low  dam  at  Lower  Machuca 866,040 

Low  dam  at  Boca  San  Carlos 2,633,124 

$4,544,733 

Low  dam  at  Lower  Machuca $1,240,785 

Low  dam  at  Conchuda 2,721,411 

Low  dam  at  Boca  San  Carlos 2,633,124 

$6,595,320 

Both  of  the  above  schemes  would  require  in 
addition  a  large  amount  of  rock  excavation  in 
the  river  to  create  navigable  channels  in  the 
pools,  which  would  be  avoided  by  the  higher 
single  dam. 

High  dam  at  Boca  San  Carlos,  of  concrete, 
$4,570,340. 

San  Carlos  and  San  Francisco  Embankment 

Lines. 

The  hills  to  the  southeast  of  the  San  Carlos 
river  contain  depressions  which  would  have  to 
be  closed  by  earthen  embankments  to  provide 
for  the  Menocal  project,  with  weirs  through  the 
saddles.  The  depth  to  hard  rock  varies  from 
probably  60  to  100  feet,  but  as  the  San  Carlos 
embankments  will  be  avoided  by  the  change  of 
the  dam  site  to  a  point  al>ove  the  Boca  San  Car- 
los, no  further  discussion  of  its  embankment  line 
is  required.  It  would  be  necessary,  however,  to 
extend  the  San  Francisco  embankment  line  from 
Ochoa  up  the  left  bank  of  the  river  to  comiect 
with  this  new  location,  involving  heavy  w-ork. 


REPORT  OP  THE  •  COMMISSION 


35 


Embankment  Foundations. 

To  ascertain  the  character  of  the  material  un- 
deriying  the  proposed  embankments  crossing  the 
Florida,  San  Francisco,  Nicholson  and  Chan- 
chos  depressions,  deep  borings  were  made  in  each 
which  revealed  the  residual  clav  and  soft  rock 
beneath  the  alluvium  but  in  thinner  strata  than 
on  the  hills. 

"  The  rock  is  only  moderately  hard,  consisting 
chiefly  of  talcose  volcanic  tuff  wth  a  thin  bed 
of  earthy  limestone.''  The  silt  in  these  depres- 
sions and  swamps  apparently  extends  to  about 
ten  feet  below  sea  level  and  renders  it  desirable 
to  reduce  the  height  of  the  embankments  as 
much  as  possible.  All  the  routes  traverse  the 
reach  on  the  left  bank  of  the  San  Juan  from 
Boca  San  Carlos  to  the  San  Francisco  near  its 
mouth  and  hence  cross  these  lateral  tributaries, 
but  at  different  elevations  dependent  upon  the 
number  and  location  of  the  locks. 

Dams  on  the  Western  Division. 
The  LuV  Flor  Site. 

Much  has  been  said  pro  and  con  concerning 
the  possibility  of  constructing  a  dam  at  this  site, 
and  the  Board  of  1895,  basing  its  conclusions 
upon  certain  exhibits  as  to  geological  structure, 
declared  it  inexpedient,  in  view  of  the  slight  ad- 
vantages and  the  ability  to  construct  a  canalized 
channel  at  a  somewhat  greater  cost  on  the  left 
bank  of  tlie  Rio  Grande. 

In  the  light  of  more  recent  borings  and  their 
interpretation  by  Dr.  Hayes,  this  Commission  is 
of  opinion  that  a  dam  at  this  point  is  practicable. 

BcEN  Retiro. 

The  summit  level  would  terminate  at  Buen 
Retire,  about  0  miles  from  the  lake,  where  the 
topography  is  well  adapted  for  the  puiiK>se,  as  it 
affords  opportunities  for  spillways  directly  into 


the  bed  of  the  Rio  Grande  and  Guachipilin,  and 
for  a  good  lock  site.  Here  a  small  ovoidal  hill 
rises  from  the  bottom  of  the  valley  "  composed 
of  a  calcareous  shale  more  or  less  disintegrated, 
but  sufBciently  firm  for  foundation  purposes." 
The  rock  is  about  50  feet  above  sea  level,  and 
comparatively  little  silt  would  have  to  be  exca-^ 
vated  to  place  the  foundations.  The  regulating 
works  with  the  lock  will  close  the  summit  level, 
making  it  unnecessary  to  build  a  dam  at  this  site. 
Xo  other  dams  are  required  on  the  west  side 
under  any  of  the  variants. 

Canal  Locks. 

On  the  route  selected  as  a  basis  for  the  esti- 
mate it  is  proposed  to  construct  6  locks  of  18.41 
feet  lift  each  on  the  eastern  division,  giving  a 
total  of  110.46  feet,  and  four  locks  of  29  feet 
lift  each  on  the  western  division,  giving  a  total  of 
116  feet,  the  difference  of  5.54  feet  being  due 
to  the  difference  in  rise  of  tides  in  the  two  oceans. 

In  estimating  the  cost  of  the  locks  the  large 
Poe  lock  at  the  Sault  Ste.  Marie  canal  at  the 
outlet  of  Lake  Superior  was  taken  as  a  standard, 
and  the  dimensions  of  lock  chamber,  fore-  and 
tail-bays,  gates,  culverts,  etc.,  were  modified  to 
adapt  them  to  the  present  requirements.  The 
lock  pits  were  extended  to  15  feet  below  the 
floor  to  provide  for  the  culverts  and  valves  and 
the  necessary  foundations.  The  following  are 
the  dimensions  used  for  one  of  the  18.41  feet 
lift  locks: 

Number  of  culverts 4 

Length  of  floor  and  side  walls 939.5    ft. 

Width  of  floor  in  the  clear 80.       " 

Height  of  side  walls  =  lift  +  draft 

+  4  ft 52.41  " 

Length  of  sides  between  abutments.  .601.75  " 

Width  of  side  walls  at  top 10. 

Width  of  side  walls  at  bottom 21.53  *' 

Width  of  abutment  walls  at  quoins  .  .    31.77  " 


36 


NICARAGUA  CANAL  COMMISSION 


On  the  western  division  the  topography  is 
such  that  the  best  results  are  obtained  bv  the  use 
of  four  locks  having  the  same  dimensions  as  to 
length  and  breadth,  the  only  modification  being 
in  the  lift  and  thickness  of  the  walls  and  foun- 
dations. 

Upon  this  basis  the  6  locks  on  the 

eastern  division  will  cost $0,560,400 

The  4  locks  on  the  western  division 

will  cost   7,412,580 

Making  the  total  cost $16,972,980 

QUAXTITIES. 

The  general  advantages  and  disadvantages  of 
the  several  locations  have  alreadv  been  stated 
under  the  head  of  ^'  Projects  and  Routes,"  but 
no  final  location  nor  estimate  could  be  com- 
pleted until  after  the  quantities  of  the  different 
classes  of  material  on  the  several  routes  had  been 
detennined. 

As  a  large  number  of  variants  are  |X)ssible, 
particularly  on  that  part  of  the  route  lying  be- 
tween Boca  San  Carlos  and  the  sea,  and  as  it 
was  impossible  to  determine  before  the  prelimi- 
nary sun^eys  were  completed  and  plotted  which 
would  give  promise  of  the  best  results,  the  de- 
tailed geological  examination  by  borings  on  any 
specific  route  had  to  be  defeiTcd  for  a  later  date. 
The  classification  which  has  been  made  along 
these  low  level  routes  is  therefore  based  upon 
outcrops,  borings  by  the  Canal  Company  con- 
firmed by  the  Commission  at  a  few  |)oints,  and 
an  examination  of  the  region,  which  is  believed 
to  be  ample  for  the  puii.)ose  of  an  estimate. 

The  collection,  plotting  and  computing  of 
tliese  data  have  required  considerable  time,  but 
so  far  as  quantities  are  coneenied  they  are  quite 
reliable.  There  may  be  variations  in  the  classi- 
fication where  the  lines  of  8ei>aration  between 


different  materials  merge  into  one  another,  but 
they  will  be  more  or  less  equalized,  so  that  errors 
due  to  this  cause  will  be  small. 

For  more  convenient  reference  and  ^ompari- 
son  of  the  quantities  under  the  variations  of  line 
and  grade,  they  have  been  aiTanged  in  a  table  ' 
which  gives  the  amount  of  excavation  and  em- 
bankment in  each  division  and  for  each  project 
and  class  of  material,  excepting  for  the  harbors, 
railroad  and  dams.  The  cost  of  the  dams,  locks, 
weirs,  and  other  structures  is  given  in  the  item 
entitled  "  Auxiliary  Cost,"  appended  to  each  di- 
vision. 

By  the  aid  of  this  tabular  statement  of  quan- 
tities an  estimate  of  the  cost  of  constructing  the 
canal  trunk  may  readily  be  obtained  by  apply- 
ing any  suitable  unit  price  to  the  factors  as 
stated.  The  amount  of  dredging  for  the  two 
harbors,  not  included  in  the  table,  which  should 
be  added  to  the  totals,  is,  for  Grey  town,  10,- 
748,900  cubic  yards,  and  for  Brito,  9,500,000 
cubic  yards.  The  jetty  and  other  harbor  work 
is  not  included  in  the  table,  but  is  stated  in  the 
estimates. 

For  the  route  recommended  bv  the  Commis- 
sion,  passing  to  the  nortli  side  of  Silico  lake,  fol- 
lowing the  left  bank  of  the  San  Juan  and  Rio 
Grande  rivers,  and  having  a  bottom  width  of 
150  feet,  ^\dth  10  locks  and  one  dam,  the  quan- 
tities from  ocean  to  ocean,  exclusive  of  the  rail- 
road, are: 

Cu.  yds. 

Dredging,  river  and  coastal  plain.  .  01,738,842 

Dredging,  lake  and  harbors 37,557,750 

Earth  excavation  and  embankment.  29,907,990 

Disintegi-ated  rock • 15,248,312 

Solid  rock 7,573,992 

Rock  under  water 754,378 

152,781,270 


» See  '*  Table  of  Quantities  "  in  Atlas. 


REPORT   OF   THE   COMMISSION 


37 


Unit  Prices. 

The  Commission  has  endeavoretl  to  reach  con- 
clusions in  respect  to  the  probable  cost  of  the 
canal  that  w-ill  be  fair  and  just.  It  has  tried  to 
have  the  figures  represent  the  probable  cost  of 
the  canal  as  nearly  as  can  be  ascertained,  with- 
out  being  too  high  or  too  low.  It  must  be  ad- 
mitted, however,  that  any  estimate?  of  probable 
cost  is  to  some  extent  a  matter  of  judgment.  It 
is  not  possible  to  determine  this  matter  with  ab- 
solute certainty,  as  many  of  the  elements  on 
which  one's  judgment  would  be  based  are  not 
accurately  known.  One's  experience  in  like 
work,  and  the  experience  of  others,  are.  the  only 
guides.  There  has  never  yet  been  a  work  of 
.similar  character  executed  under  exactly  similar 
conditions,  and  it  should  be  remembered  that 
work  on  a  small  scale,  or  which  is  greatly  dis- 
tributed and  not  en  masse,  involves  more  loss  of 
time  and  labor  and  is  consequently  more  expen- 
sive. The  work  on  the  Panama  canal  would 
perhaps  come  near  it  in  some  respects,  but  no 
one  would  think  of  comparing  the  extravagant 
methods  which  characterized  the  early  history  of 
that  enterprise  with  the  methods  that  should  be 
employed  on  this. 

The  latest  work  of  magnitude  of  this  char- 
acter which  affords  to  some  degree  a  means  of 
comparison  is  the  Chicago  drainage  canal.  The 
total  excavation  for  this  work  amounted  to  about 
12,318,000  cubic  yards  of  rock  and  20,087,000 
cubic  yards  of  earth,  a  total  of  38,405,000  cubic 
yards,  of  which  about  10  per  cent,  was  dredging. 

The  earth  was  of  every  variety  from  soft  mud  to 

«  t.' 

hard  indurated  clay  with  boulders;  all  being 
included  under  the  name  of  "  glacial  drift." 
The  rock  was  the  Joliet  limestone,  stratitied  in 
nearly  horizontal  layers,  and  Is  described  as  ideal 
for  ease  in  excavation.  The  proi)ortiou  of  rock 
to  earth  is  less  in  Nicaragua  than  in  the  Chicago 


drainage  canal.  The  actual  average  price  paid 
for  excavating  '"  glacial  drift "  at  Chicago  was 
29  cents  per  cubic  yard.  The  average  cost  of 
rock  was  77  cents.  If  the  Nicaragua  canal  were 
locat<?d  near  Chicago  and  its  rock  and  earth  simi- 
lar in  character  to  those  of  the  Chicago  drainage 
canal,  it  is  probable  that  the  average  cost  for 
earth  excavation  would  be  the  same  in  each. 
The  earth  in  the  Nicaragua  canal  varies  in  char- 
acter from  stiff,  indurated  clav  to  diluted  silt. 
The  range  is  equally  wide  in  the  Chicago  drain- 
age canal.  It  cannot  be  asserted  that  the  earth 
is  alike  in  the  two  places,  but  it  is  l)elieved  that 
it  may  be  substantially  so.  lender  such  circum- 
stances  it  might  be  fairly  assumed  that  the  aver- 
age cost  of  earth  excavation,  if  the  canal  were 
located  near  Chicago,  would  be  29  cents. 

As  the  Chicago  drainage  canal  affords  the 
nearest  precedent  available  and  as  the  actual 
average  prices  of  that  work  have  been  taken  as 
a  basis,  it  is  necessary  to  state  the  classification  of 
the  material  as  specified  for  that  work,  which 
was  as  follows: 

^'  For  the  purpose  of  letting  the  contracts  the 
material  to  be  excavatx^d  was  divided  into  two 
classes,  rock  and  '  glacial  drift.'  The  first  tenn 
explains  itself,  but  the  character  of  the  material 
termed  ^  glacial  drift,^  this  being  an  entirely  ar- 
bitrary classification,  needs  some  further  expla- 
nation. As  defined  in  the  specifications, '  glacial 
drift  shall  comprise  the  top  soil,  earth,  muck, 
sand,  gravel,  clay,  hardpan,  boulders,  fragmen- 
tary rock  displaced  from  its  original  bed,  and  any 
other  material  that  overlies  bed  rock.'  In  fact, 
all  these  materials  are  found  in  all  degrees  of 
intennixture,  from  soft  black  muck,  which  can 
be  pumped  with  centrifugal  pumps,  to  a  con- 
glomerate of  sand,  gravel,  clay,  and  boulders 
cemented  together  with  almost  the  hardness  of 
rock,  and  only  to  be  excavated  bv  means  of  the 


38 


NICARAGUA   CANAL  COMMISSION 


strongest  steam  shovels,  and  sometimes  even  re- 
quiring blasting  to  break  it  up." 

In  Nicaragua  the  rock  on  the  western  division 
is  chiefly  a  calcareous  shale,  thinly  stratified  and 
much  broken.  Some  pits  of  considerable  depth 
have  been  excavated  without  blasting,  and  the 
rock  has  been  used  for  macadamizing  the  roads. 
It  is  believed  that  a  large  part  of  this  rock  could 
be  excavated  with  steam  shovels  without  blast- 
ing. It  is  drilled  slightly  easier  than  the  Chi- 
cago limestone,  and  is  more  brittle.  The  loca- 
tion of  the  spoil  banks  would  be  quite  similar  to 
that  of  the  Chicago  work.  It  is  therefore  prob- 
able that  some  of  this  rock  could  be  excavated 
for  a  price  slightly  cheaper  than  the  Chicago 
rock.  Some  of  it,  however,  it  is  known,  will 
cost  more.  It  is  probable  that,  taken  as  a  whole, 
it  could  be  done  for  the  same  price,  and  it  is  so 
assumed. 

Between  Lake  Nicaragua  and  the  Caribbean 
sea,  viz.,  the  eastern  division,  the  rock  is  basalt, 
dacite,  sandstone  and  volcanic  tuff.  The  basalt 
and  dacite  are  both  considerably  harder  to  drill 
and  blast  than  the  Chicago  limestone.  In  the 
larger  cuts  the  waste  material  will  have  to  be 
transported  some  distance  to  the  dumping 
grounds.  For  these  reasons  it  is  estimated  that 
the  cost  per  yard  will  be  increased  10  cents. 
Therefore  it  is  assumed  that  if  the  Nicaragua 
canal  were  located  near  Chicago,  the  cost  of  ex- 
cavating its  rock  would  be  87  cents  per  cubic 
yard  on  the  eastern  division  and  77  cents  per 
cubic  yard  on  the  western  division. 

With  reference  to  the  actual  cost  of  work  at 
Chicago  Mr.  Isham  Randolph,  the  present  Chief 
Engineer  of  that  work,  writes  as  follows: 

"  The  prices  on  our  work  ranged  from  59  cents 
to  80  cents  for  solid  rock  and  from  19.9  cents 
to  56  cents  per  cubic  yard  for  glacial  drift.  This 
glacial  drift,  however,  covered  material  which 


under  railroad  specifications  would  come  under 
the  heads  of  loose  rock  and  hardpan.  The  av- 
erage price  paid  on  this  work  per  cubic  yard 
was  for  solid  rock  77.3  cents,  for  glacial  drift 
28.7  cents." 

"  In  the  light  of  our  experience  I  believe  that 
a  work  of  like  magnitude  prosecuted  under  simi- 
lar conditions  could  be  put  under  contract  at  a 
reduction  of  about  15  per  cent,  from  our  ruling 
prices;  in  other  words,  that  rock  work  should  be 
done  for  65  cents  and  earth  for  24i  to  25  cents, 
which  prices  would,  I  believe,  provide  a  fair 
margin  of  profit  for  the  contractor." 

Mr.  Lyman  S.  Cooley,  former  Chief  Engineer 
and  Director  of  this  work  also  concurs  in  this 
opinion,  stating  that  some  very  hard  glacial 
drift  was  removed  for  26  cents  per  cubic  yard 
and  that  the  actual  cost  of  rock  work  was  about 
as  follows: 

Per  cu.  yd. 


For  plant 15  cts. 

loading     15 

hoisting   15 

channeling 5 

drilling    6 

explosives 8 


a 

a 
a 


Total 

including  contractors'  profits. 


64 


t( 


It  yet  remains  to  assign  the  relative  cost  of 
work  in  the  United  States  and  in  Central  Amer- 
ica. This  will  involve  greater  uncertainty,  for 
the  reason  that  there  have  been  no  large  works 
in  Central  America  with  which  comparison 
could  be  made.  There  has,  however,  been 
some  railroad  building  in  all  of  the  Central 
American  States,  often  in  amount  sufficiently 
large  to  require  the  importation  of  labor,  thus 
making  the  conditions  of  labor  similar  to  those 
which  would  obtain  if  the  Nicaragua  canal 
should  be  built. 


REPORT   OF   THE   COMMISSION 


39 


Mr.  Wm.  H.  Keith,  Contractor,  reports  the 
cost  of  work  on  the  National  Railway  of  Costa 
Rica  to  be  for  solid  rock  60  cents  in  gold  per 
cubic  yard,  for  loose  rock  30  cents  in  gold  per 
cubic  yard,  and  dry  earth  18  cents  in  gold  per 
cubic  yard,  concrete  in  place,  including  "forms," 
$9.00  per  cubic  yard. 

Mr.  Louis  Wichmann,  General  Manager  of 
the  Atlas  Company,  who  has  been  engaged  in 
building  a  railroad,  six  miles  and  a  half  in 
length  and  2i  feet  gage,  from  Greytown  to  the 
lower  San  Juan  river,  states  "  that  the  total  cost 
per  cubic  yard  of  excavation  on  the  Silico  Rail- 
road is  $1.25  Nicaraguan  currency,  equal  to  50 
cents  gold." 

In  explanation  of  this  abnormally  high  price, 
he  says  that  "  the  disadvantages  were  extremely 
bad  weather,  especially  in  June  and  July,  during 
which  time  we  had  some  seven  weeks  of  con- 
tinuous rain,  and  the  principal  part  of  the  ma- 
terial being  heavy  clay,  it  was  very  difficult  to 
handle." 

"  Being  entirely  without  mechanical  applian- 
ces, I  had  to  rely  on  manual  labor,  which,  con- 
sidering the  nature  of  the  soil  and  constant  down- 
pour of  rain,  has  proved  a  great  drawback." 

"  The  material  on  the  first  big  through  cut  at 
the  Silico  end  consisted  of  conglomerate  with 
large  round  boulders,  which  could  only  be  re- 
moved after  blasting,  and  unfortunately,  owing 
to  the  American-Spanish  war,  we  were  unable 
to  secure  explosives  at  the  time  when  they  were 
most  needed." 

Other  difficulties  mentioned  were  the  long  car- 
riage to  the  spoil  banks  and  the  fact  that  all  sup- 
plies, tools  and  provisions  had  to  be  transported 
on  the  backs  of  the  laborers. 

These  conditions  and  prices  cannot  therefore 
be  cited  as  being  comparable  to  the  probable 
cost  of  90  great  a  work  as  the  construction  of  this 


canal,  where  the  most  modern  appliances  should 
be  used. 

Quite  recently  it  is  credibly  stated  that  the 
Silico  railroad  had  cost  more  than  was  antici- 
pated, and  that  the  total  cost  was  from  $110,000 
to  $120,000,  length  6^  miles,  equivalent  to  $16,- 
923  to  $18,461  per  mile,  and  that  this  cost  in- 
cluded everything — road-bed,  rails,  rolling  stock, 
bodegas,  wharves,  and  all  terminal  facilities  at 
both  ends.  It  was  built  in  very  bad  weather  and 
under  great  difficulties.  The  rolling  stock  con- 
sists of  one  locomotive,  eight  freight  ears,  two 
construction  cars  and  two  passenger  cars,  which 
were  imported.  The  ties  on  this  road  were  fur- 
nished and  put  in  place  for  about  24:  cents  apiece 
in  gold. 

'*  The  cost  of  excavation  varied  from  50  cents 
to  $1.00  (Xicaraguan  currency)  per  cubic  yard, 
depending  upon  the  condition  of  the  weather 
and  the  labor.  During  the  early  part  of  the 
construction.  Fortune  island  negroes  were  em- 
ployed, but  were  found  unsuitable  for  the  work. 
While  these  men  were  employed,  the  cost  of  ex- 
cavation was  rather  high.  The  labor  now  con- 
sists of  natives  and  Jamaicans,  and  the  cost  of 
excavation  is  kept  below  70  cents. 

"  The  cost  of  food  for  each  man  per  day 
varied  from  52  cents  to  75  cents.  This  is  in- 
cluded in  the  cost  of  excavation.  The  material 
chiefly  excavated  was  blue  and  brown  clay.  In 
handling  the  blue  clay,  the  rains  had  no  eflFect 
upon  it  whatever.  The  brown  clay  becomes 
rather  difficult  to  shovel  when  wet,  as  it  has  a 
tendency  to  stick.  In  the  former,  the  same 
amount  of  material  can  be  hauled  on  a  wet  day 
as  on  a  drj-  day.  The  haul  in  some  cases  was 
over  four  hundred  feet.  During  rainy  days  the 
work  was  not  interrupted. 

"  The  rate  of  exchange  at  present  is  200  per 
cent,  premium." 


40 


NICARAGUA   CANAL  COMMISSION 


An  engineer  of  large  experience  in  Guatemala 
states  that  prices  for  grading  on  railroad  work  in 
that  country  were  as  follows:  for  earth,  from  30 
to  40  cents;  for  loose  rock,  from  05  to  85  cents, 
and  for  solid  rock,  from  $1.40  to  $1.75,  exclusive 
of  cost  of  administration  and  engineering.  The 
prices  paid  for  clearing  ranged  from  $G5  per 
acre  on  the  swamp  work,  to  as  low  as  $25  for  the 
upper  end  of  the  line.  The  cost  of  masonry, 
where  the  haul  was  less  than  half  a  mile,  was 
about  $24  to  $28  for  first-class,  $14  to  $18  for 
second,  and  $10  to  $12  for  third.  "  In  all  of  the 
foregoing,  prices  are  expressed  in  the  silver  of 
the  countiy."  The  rate  of  exchange  is  not 
stated. 

Another  engineer,  also  in  Guatemala,  states 
that  the  unit  prices  there  were,  for  earth  40  cents, 
telpetate  $1.00,  loose  rock  $1.25,  solid  rock 
$1.80,  masonrv'  exclusive  of  cement,  third  class 
$10,  second  class  $16  and  first  class  $25  per  cubic 
yard.  ''  These  prices  include  a  good  profit  if 
work  is  propc^rly  handled."  They  are  all  on  a 
silver  basis.  Converted  into  gold  at  the  Nicara- 
gua ratio  they  Avould  be:  for  earth,  16  cents;  tel- 
petate, 40  cents;  loose  rock,  50  cents;  solid  rock, 
72  cents;  third-class  masonry,  $4.00;  second- 
class,  $6.40;  first-class,  $10.00. 

Mr.  M.  P.  Carter,  Civil  Engineer  on  the  con- 
struction of  the  Cauca  Railroad  in  Colombia, 
where  the  rainfall  is  said  to  exceed  300  inches  a 
year,  testified  under  oath  that  "  a  man  working 
in  earth  w-ork  would  move  three  or  four  yards 
a  day  at  40  cents  a  yard,  that  is  the  average.  For 
loose  rock,  that  has  been  loosened  a  little  with  a 
pick,  he  might  move  a  yard  and  a  half  or  two 
yards  a  day  at  80  cents  a  yard,  and  for  conglom^ 
erate,  a  man  would  not  move  more  than  two- 
thirds  or  three-quarters  of  a  yard  per  day  at 
$2.20  per  yard."  All  of  the  above  prices  are  in 
Colombian  money,  wdiicli  would  make  the  equiv- 


alents in  gold  for  earth,  17.2  cents,  for  loose 
rock,  34.4  cents;  for  conglomerate,  92  cents. 

(Extract  from  a  letter  from  Mr.  Harold  R. 
Miller,  dated  Atlas  Line  of  Mail  Steamers,  New 
York,  April  22,  1899.) 

"  The  three  rates  for  earthwork  and  conglome- 
rate were  40  cents,  80  cents,  and  $2.20,  Colom- 
bian, as  per  ^Ir.  Carter's  evidence.  TTie  ex- 
change at  that  time  was  130-150,  say  140  per 
cent. ;  that  makes  17  cents,  34  cents,  and  92  cents, 
gold.  To-day  the  exchange  is  230  per  cent., 
viz:  $1  gold  is  $3.30  Colombian.  Labor,  of 
course,  has  not  risen  in  proportion  with  the  ex- 
change, so  that  constniction  work  is  really  cheap- 
er to-day  than  then,  because  contractors  get  more 
cuiTency  for  their  gold  and  pay  about  the  same 
rates.  Labor  is  about  $1  Colombian  in  the  in- 
terior, $1.40  to  $1.60  on  the  coast.  The  condi- 
tions on  the  isthmus  are  different  from  the  rest 
of  the  Republic,  owing  to  the  silver  currency, 
which  alone  prevails  on  the  isthmus;  the  rest  of 
the  Republic  iLses  paper,  which  has  about  20  per 
cent,  discoinit  as  compared  with  silver." 

(Extract  from  communication,  dated  October 
30,  1897,  from  Edwin  F.  Smith,  Civil  and  Hy- 
draulic Engineer.) 

"  In  conclusion,  I  desire  to  say  that,  .  .  pro- 
cesses of  dredging  have  improved  very  much  in 
recent  years,  and  large  companies  in  the  United 
States  would,  I  think,  be  found  willing  to  take 
such  contracts  at  Greytown,  and  on  the  line  of 
the  Nicaragua  canal  at  less  than  the  figures 
given  in  the  estimates  of  the  Canal  Company. 

"  This  is  true  not  only  of  dredging,  but  also 
of  rock  excavation.  There  are  construction  com- 
panies and  contractors  handling  material  on  the 
Chicago  drainage  canal  wntli  modern  appliances, 
wdio  would,  no  doubt,  eagerly  compete  for  such 
contracts  as  those  of  the  rock  cut  through  the 
Eastern  Divide  and  the  building  of  the  Ochoa 


REPORT   OF  THE  COMMISSION 


41 


dam,  and  the  dredging  of  Grey  town  harbor  and 
the  canal  through  the  lagoons." 

(Extract  from  a  communication  from  Col.  T. 
P.  Roberts,  Chief  Engineer  Monongahela  Im- 
provement.) 

''  On  the  Nicaragua  canal,  if  extra  good  prices 
are  paid  foremen  and  bosses,  the  actual  cost  of 
work  will  not  be  much  in  excess  of  that  for 
which  it  could  be  done  here.  A  general  increase 
of  25  per  cent,  over  American  prices  ought  to 
be  sufficient.  While  I  would  thus  suggest  a 
reasonable  unit  price  for  items  of  labor,  I  would 
advise  a  liberal  percentage  on  the  whole  work,  to 
cover  engineering  and  management.  Admin- 
istration ex}>enses  will  doubtless  be  very  high  at 
first,  but  this  it^^m  will  diminish  after  the  officials 
have  become  acclimatized.  Physicians  and 
sanitary  engineers  should  be  employed  to  select 
the  i)laces  for  camps,  provide  the  water  supply, 
and  look  after  the  drainage.  If  this  be  properly 
done,  the  cost  for  hospital  service  would  not  be 
great.  I  do  not  see  why  this  item  should  be  dif- 
ferentiated  A  millage  tax  on  all  salar- 
ies and  wages  should  be  fixed  to  maintain  hos- 
pitals. 

"  It  has  been  my  observation  for  several  years 
past  that  American  engineers  have  been  overes- 
timating the  cost  of  work.  They  appear  to  me 
to  not  fully  realize  the  wonderful  improvements 
which  have  been  made  in  this  countiy.  Many 
of  them  still  think  that  French  and  German 
methods  on  canal  work  admit  of  little  improve- 
ment, but  such  engineers  have  not  been  atten- 
tive students  of  the  Chicago  drainage  canal  ex- 
perience. 

""  In  July  of  this  year,  six  locks  and  dams  were 
let  on  the  Monongahela  river.  The  United 
States  Engineers'  estimate  for  them  all  was 
about  $1,200,000,  which  amount  I  thought  was 
about  the  right  thing,  but,  although  the  estimate 


was  publicly  known,  a  number  of  responsible 
contractors  bid  less  than  $800,000,  and  it  was 
actually  awarded  for  less  than  $700,000.  The 
bidder  failing  to  isecure  bondsmen,  the  Depart- 
ment ordered  another  letting." 

For  convenience  of  comparison  these  prices 
are  tabulated  as  follows: 

Earth.  SoUd  rock. 

Chicago  basis. . .  .29  77 

Earth.       Loose  rock.      ttoUd  rock. 

Costa  Rica 18  30  60 

Guatemala    14  30  63 

16  50  72 

Colombia 17  34  92 


Average    . .  .16^ 


36 


71J 


From  this  it  appears  that  the  actual  cost  of 
earth  work  in  these  tropical  countries  is  in  gen- 
eral less  than  that  given  for  the  Chicago  basis. 
The  average  for  earth  and  loose  rock  is  26  cents, 
which  is  less  than  the  Chicago  price  of  29.  The 
average  of  the  rock  work  is  also  five  cents  below 
that  at  Chicago,  so  that  it  would  seem  that  the 
statement  of  Mr.  Shunk,  Chief  Engineer  of 
the  Intercontinental  R.  R.  Commission,  is  ap- 
parently correct  that  *'  an  estimate  of  like  work 
at  home  would  be  fairly  applicable  down 
there.'' 

In  view,  however,  of  the  difiiculties  of  secur- 
ing a  sufficient  supply  of  laborers  for  so  great  a 
work,  and  of  regulating  their  wages,  the  Com- 
mission has  concluded  to  increase  the  actual  av- 
erage prices  paid  at  Chicago  by  33  J  per  cent,  for 
all  earth  and  rock  work  on  the  western  division 
and  by  50  per  cent,  for  work  on  the  eastern  di- 
vision, after  allowing  an  increase  of  10  cents  for 
rock  on  the  eastern  division  because  of  local 
differences  and  character  of  material. 

The  prices  applied  to  the  quantities  will  there- 
fore be  as  follows: 


42 


NICARAGUA  CANAL  COMMISSION 


On  the  East  Side. 

For  Greytown  harbor,  dredg- 
ing   $     .25  per  cu.  yd. 

For  Greytown  harbor,  jetties.     2.50  "    "     *' 

For  dry  earth  excavation 44:  "    "     " 

For  solid  rock  excavation. . . .      1.30  "    "     " 

For  dredging  in  upper  river.  .        .30  "    "     ^' 

For  dredging  in  lake 20  "    "     " 

For  rock  under  water 5.00  "    *'     " 

Timber  cribs 3.25  "    ''     " 

Clay  puddle  and  back  filling, 
exclusive  of  cost  of  excava- 
tion         .50  "    "     '' 

Concrete   in   structures   other 

than  locks    8.30  "    "     " 

Concrete  in  locks 7.23  "    "     " 

Stone  pitching  on  embank- 
ments        2.00  "   sq.  yd. 

Timber  in  structures 60.00  "  M.B.M. 

Clearing 75.00  "  acre. 

Clearing  and  grubbing 100.00  "      " 

On  the  West  Side. 

For  dry  earth  excavation. . .  .$     .39  per  cu.  yd. 

For  solid  rock  excavation 1.03  "    "     " 

For  dredging  harbor 20  "    "     " 

For  rock  under  water 5.00  "    "     " 

For  jetties 2.00  "    "     " 

Timber  cribs 3.00  "    "     " 

Clay  puddle  and  back  filling, 
exclusive  of  cost  of  excava- 
tion     50  "    "     " 

Concrete   in   structures   other 

than  locks 8.30  "    "     " 

Concrete  in  locks 7.23  "    "     " 

Stone  pitching  on  embank- 
ments        1.75  "    sq.  yd. 

Timber  in  structures 60.00  "  M.B.M. 

Clearing 75.00  "  acre. 

Clearing  and  grubbing 100.00  "      " 

The  prices  for  structural  work  of  locks  and 
weirs  are  based  on  the  cost  of  similar  work  in 
the  United  States,  to  which  33  per  cent,  has 
been  added  for  diflFerence  of  location,  including 
climate,  etc. 


Feasibilfiy. 

Under  this  division  of  the  subject,  the  Com- 
mission would  respectfully  submit  that  it  has 
failed  to  find  any  competent  authority  that  de- 
nies the  feasibility  of  constructing  a  canal  across 
Nicaragua. 

The  feasibilitv  of  the  canal  is  conceded  for 
the  following  reasons: 

.  1.  There  are  at  this  date  sufficient  precedents 
for  ship  canals  capable  of  passing  the  largest 
vessels,  so  that  any  question  of  the  navigation  of 
such  a  channel  is  eliminated. 

2.  The  ability  to  construct  and  operate  locks 
of  the  requisite  dimensions  is  sufficiently  estab- 
lished by  existing  structures  on  the  Manchester 
and  Keil  canals,  at  Davis  island  on  the  Ohio, 
and  at  the  St.  Mary's  canal,  Michigan. 

3.  The  possibility  of  constructing  the  neces- 
sary dams,  weirs,  sluices  and  embankments, 
which  shall  be  sufficiently  stable  and  imperme- 
able to  control  the  water  required  for  naviga- 
tion, as  well  as  to  regulate  the  floods,  is  within 
the  resources  of  the  engineering  profession  and 
is  fully  demonstrated  by  the  many  hundreds  of 
miles  of  embankments,  levees  and  dams,  both  at 
home  and  abroad.  There  is  no  reason  to  doubt 
the  ability  to  build  them  out  of  the  native  rocks 
and  earth  and  to  give  them  the  required  strength 
and  tightness  to  retain  or  to  discharge  the  water 
with  safety. 

4. .  There  is  no  question  as  to  the  adequacy  of 
the  supply  of  water  for  all  purposes  at  all  sea- 
sons nor  as  to  its  control  in  times  of  flood. 

5.  Neither  is  there  any  doubt  with  reference 
to  the  ability  to  secure  good  supporting  ground 
for  the  trunk  of  the  canal  nor  suitable  sites  for 
locks  and  dams. 

6.  The  harbor  question  is  only  a  matter  of 
money  and  it  is  believed  that  good,  capacious 
and  safe  artificial  harbors  can  be  created  at  a 


REPORT   OF  THE  COMMISSION 


43 


reasonable  cost  In  brief,  this  Commission  sees 
no  reason  to  doubt  the  entire  feasibility  of  the 
project,  but  it  realizes  the  necessity  of  exercis- 
ing due  care  in  the  preparation  of  the  specifica- 
tions and  in  the  conduct  of  the  work,  that  the 
details  of  construction  l)e  tlioroughly  inspected 
and  properly  executeii  under  competent  super- 
vision. 

Estimate. 

After  a  careful  analysis  and  comparison  of  the 
physical  features  and  quantities  aflFecting  the 
numerous  variants,  the  Commission  has  selected 
that  route  which  it  believes  will  give  the  best 
results. 

This  route,  starting  from  the  harbor  at  Grey- 
town,  crosses  the  coastal  plain,  passes  to  the 
north  of  Lake  Silico,  and  up  the  left  bank  of  the 
San  Juan  to  the  dam  at  Boca  San  Carlos,  thence 
follows  the  improved  river  channel,  crosses  the 
lake,  and  traverses  the  valleys  of  the  Lajas  and 
Eio  Grande  to  Brito  on  the  Pacific. 

It  is  characterized  by  6  locks  on  the  eastern 


division,  having  a  lift  of  18.41  feet,  all  Mng 
east  of  the  dam,  and  4  locks  on  the  western  di- 
vision, having  a  lift  of  29  feet.  The  summit 
level  extends  from  the  lock  .43  of  a  mile  east  of 
the  beginning  of  the  cut  at  Boca  San  Carlos  to 
the  lock  1.80  miles  west  of  Buen  Retiro,  a  dis- 
tance of  139.3  miles. 

The  details  of  the  estimates  are  stated  in  the 
reports  of  the  assistants  hereto  appended,  and  it 
will  suffice  here  to  summarize  and  classify  the 
quantities  for  the  excavation  of  the  canal  trunk 
and  to  affix  their  unit  prices  in  order  to  ascer- 
tain the  approximate  cost.  The  auxiliary  works 
have  also  been  computed  for  each  subdivision 
separately  and  in  detail,  but  the  totals  only  are 
stated  in  this  connection.  The  calculations  are 
based  upon  a  minimum  elevation  of  104  for  the 
summit  level,  with  a  depth  of  30  feet  and  a 
minimum  bottom  width  of  150  feet,  as  set  forth 
more  particularly  under  the  "  Dimensions  of  the 
Canal." 


General  Estibiate  of  Cost. 
East  side,  with  50  per  cent,  over  Chicago  prices  for  earth  and  rock. 


Classification.  Cu.  yds. 

Earth 23,206,836 

Rock 1,309,375 

Rock  under  water 472,705 

Dredging  (harbor) 10,748,900 

Dredging  (lake) 17,308,850 

Dredging  river  «fe  canal . .  46,555,742 

Dredging  upper  river  . . .  15,183,100 

114,785,508 


Price. 

at$  .44 

"  1.30 

"  5.00 

"  .25 

"  .20 

"  .30 

"  .39 


Amount. 

$10,211,007.84 
1,702,187.50 
2,363,525.00 
2,687,225.00 
3,461,700.00 
13,966,722.60 
5,921,409.00 

$40,313,846.94 


West  side,  with  33i  per  cent  over  Chicago  prices. 


Earth 21,949,472 

Eock 6,264,617 

Rock  under  water 281,673 

Dredging  harbor 9,500,000 

37,995,762 


at$  .39 
"  1.03 
"  5.00 
"       .20 


152,781,270 


$  8,560,294.08 
6,452,555.51 
1,408,365.00 
1,900,000.00 

$18,321,214.59 

$58,635,061.53 


44 


NICARAGUA   CANAL  COMMISSION 


Auxiliary  AVorks. 

Cu.  yds. 


Classifloation. 

Amount  brought  forward 

Jetties,  Greytowii   550,000 

Jetties,  Brito 144,107 


Price. 


at  $2.50 
''     2.00 


Amount. 

$58,035,061.53 

$  1,375,000.00 

288,214.00 


$  1,063,214.00 

Concrete  dam  and  regulating  works  at  Boca  San  Carlos.  .  .  .  4,570,340.00 

4  locks  on  west  side,  28  feet  lift 7,412,580.00 

6  locks  on  west  side,  18.41  feet  lift 9,560,400.00 

Weir  on  west  side,  Buen  Retiro 1,102,300.00 

AVeirs  on  east  side  below  San  Carlos 207,890.00 

Clearing  and  grubbing  (7463  acres) 615,625.00 

Guard  gates,  timber  piers,  piling,  etc 1,089,343.00 


Miscellaneous. 

100  miles  of  R.  R.  for  construction  purj^oses,  at  $50,000 
per  mile  (double  track) 

Sanitary  and  police 

For  maintenance  of  harbors  during  construction  of  canal, 
and  for  buoys,  beacons  and  lighting    


$24,558,478.00 
$84,856,753.53 


5,000,000.00 
2,000,000.00 

1,000,000.00 


Engineering  and  administration,  6  per  cent. 


General  contingencies,  20  per  cent 


$92,856,753.00 
5,571,405.00 

$98,428,158.00 
19,685,632.00 


Total. $118,113,790.00 


For  the  cost  of  engineering  and  administra- 
tion an  estimate  of  6  per  cent,  has  been  made. 
This  estimate  is  large,  but  in  a  work  of  such 
great  importance,  the  engineering  and  superin- 
tendence must  be  thoroughly  and  carefully  done 
by  men  of  ability  and  integrity  who  w^ill  neces- 
sarily command  higher  rates  of  pay  than  would 
be  deemed  sufficient  in  the  United  States. 

An  estimate  of  20  per  cent,  for  contingencies 
has  been  made.  It  is  intended  to  cover  all 
items  of  expense  due  to  unforeseen  accidents  or 


emergencies.  Owing  to  the  extent  and  charac- 
ter of  the  work,  there  are  more  uncertainties 
than  usual,  including  that  of  labor,  which  w411 
have  to  be  largely  imported  from  the  islands  of 
the  West  Indies  and  from  our  Southern  States. 
No  work  of  this  character  and  importance  has 
ever  been  completed  within  the  tropics.  There 
is,  therefore,  nothing  to  serve  as  a  precedent  or 
guide  for  the  proper  contingent  percentage,  but 
after  careful  consideration  and  with  a  desire  to 
make  an  ample  allowance,  the  Board  has  decided 


REPORT   OF  THE   COMMISSION 


45 


to  include  an  estimate  of  20  per  cent.,  which  is 
believed  to  be  quite  sufficient  for  all  probable  ac- 
cidents or  emergencies. 

It  is  believed  that  if  honestly  and  properly 
administered,  with  money  at  command  as  re- 
quired, the  canal  can  be  built  within  the  limits 
of  the  above  estimate. 

Conclusions. 

The  Commission  after  mature  deliberation  has 
adopted  and  estimated  for  the  route  from  Brito 
to  Lake  Nicaragua,  called  Childs'  route,  variant 
Xo.  1,  and  from  the  lake  to  Grey  town,  that 
called  Lull  route,  variant  No.  1.  This  line  leav- 
ing Brito,  follows  the  left  bank  of  the  Rio 
Grande  to  near  Buen  Re  tiro,  crosses  the  West- 
ern Divide  to  the  valley  of  the  Lajas  which  it 
follows  to  Lake  Nicaragua.  Crossing  the  lake 
to  the  head  of  the  San  »Tuan  river,  it  follows  the 
upper  river  to  near  Boca  San  Carlos,  thence,  in 
excavation,  bv  the  left  bank  of  the  river  to  the 
San  Juanillo,  and  across  the  low  county  to  Grey- 
town,  passing  to  the  northward  of  Lake  Silico. 
It  requires  but  a  single  dam,  with  regulating 
works  at  both  ends  of  the  summit  level. 

The  new  location  selected  for  the  dam  at  Boca 
San  Carlos  eliminates  one  of  the  most  serious 
engineering  difficulties  by  avoiding  entirely  the 
San  Carlos  river  with  its  torrential  floods  and 
large  volume  of  sediment,  and  by  locking  down 
immediatelv  from  this  dam  the  difficulties  and 
risks  of  the  high  embankments  of  the  Menocal 
line  are  also  avoided. 

Instead  of  the  dam  at  La  Flor  a  lock  and 
regulating  works  have  been  substituted  at  Buen 
Retiro  where  the  topography  is  well  adapted  for 
the  purpose.  It  is  also  proposed  to  divide  the 
sui'plus  waters  of  the  lake  basin  between  the  east 
and  west  sides,  thus  reducing  the  velocities  in 
the   San   Juan   and   securing  ample   waste-way 


cai)a(*ity  for  the  maximum  discharge  that  can 
ever  occur,  if  stored  and  distributed  over  a  short 
period  of  time.  Ample  provision  has  also  been 
made  for  a  possible  fluctuation  of  the  lake  of  6 
feet  or  more  without  injury  to  property,  by  fix- 
ing the  elevation  of  the  bottom  of  the  canal 
sufficientlv  low  to  cover  seasons  of  minimum  rain- 
fall.  The  surveys  have  in  general  revealed  better 
physical  conditions  than  were  hitherto  supposed 
to  exist,  especially  as  to  the  amount  of  rock  in 
the  upper  river,  whereby  it  is  possible  greatly  to 
reduce  the  estimated  cost  of  construction.  This 
fact  will  account  largely  for  the  comparatively 
moderate  amount  of  the  estimate  when  the  en- 
larged dimensions  of  the  project  are  taken  into 
consideration.  Other  reductions  are  due  to  the 
improved  methods  and  machinery  available,  as 
developed  on  the  Chicago  drainage  canal,  and 
which  cannot  be  ignored  in  discussing  a  work 
of  this  magnitude. 

The  creation  of  sufficiently  capacious  interior 
harbors  presents  no  unusual  difficulties,  and  they 
can  be  secured  at  a  reasonable  cost. 

The  field  work,  under  the  authoritv  of  this 
Commission,  has  been  carefully  and  well  done, 
and  is  believed  to  be  all  that  is  necessary  for  the 
preliminary  location  of  a  canal,  and  to  deter- 
mine, within  narrow  limits,  the  final  location  of 
(lams,  lo<^ks,  and  other  constructions.  Should  a 
canal  across  Nicaragua  be  authorized,  it  will  be 
neccssar\'  to  make  further  minute  and  careful 
investigations  by  borings  to  determine  the  exact 
location  of  locks  and  dams,  for  which  this  Com- 
mission had  neither  the  time  nor  money,  nor 
would  it  have  been  justified  in  doing  work  of 
this  character  until  the  construction  of  a  canal 
was  assured.  The  computations  of  amounts  to 
be  excavated  have  been  carefully  made  and 
checked  to  guard  against  errors  and  are  believed 
to  be  accurate  within  narrow  limits.     All  pos- 


46 


NICARAGUA  CANAL  COMMISSION 


sible  information  has  been  sought  with  regard 
to  cost  of  similar  work  in  the  United  States  and 
in  Central  America,  and  a  careful  comparison 
made  of  the  probable  diflFerences  between  Nica- 
ragua and  the  United  States. 

To  determine  the  proper  unit  prices  for  ex- 
cavation the  average  of  prices  actually  paid  to 
contractors  on  the  Chicago  drainage  canal,  which 
represent  cost  of  plant,  prices  paid  for  work 
done,  and  contractors'  profits,  were  taken.  Up 
to  this  point  the  Commission  dealt  only  with 
facts.  To  the  prices  paid  at  Chicago  certain 
percentages  have  been  added  for  the  difference 
in  location,  climate,  etc.,  etc.  These  percent- 
ages are,  of  course,  a  matter  of  judgment,  upon 
which  men  may  honestlv  differ.  But  from  all 
the  information  obtainable  by  this  Commission 
and  after  careful  consideration,  with  a  desire  to 
arrive  at  a  proper  conclusion,  those  used  in  the 
estimate  are  deemed  fair  and  reasonable. 

In  obtaining  the  estimate  for  cost  of  locks  the 
prices  actually  paid  for  building  the  Govern- 
ment locks  at  the  Sault  Ste.  Marie  were  taken, 
and  33  per  cent,  was  added  for  the  difference  of 
location.  This  percentage  is  believed  to  be 
ample,  as  a  large  part  of  the  expense  of  con- 
structing the  locks  will  be  for  material,  much 
of  which  can  be  furnished  in  Nicaragua  at  the 
same  or  only  a  small  advance  upon  the  prices  in 
the  United  States. 


After  giving  due  weight  to  all  the  elements 
of  this  important  question  and  with  an  earnest 
desire  to  reach  logical  conclusions,  based  upon 
substantial  facts,  the  Commission  believes  that 
a  canal  can  be  built  across  the  isthmus  on  this 
route  for  a  sum  not  exceeding  that  stated  in  the 
estimate. 

The  dimensions  of  the  canal  proposed  are 
much  larger  than  any  hitherto  considered  and 
will  be  ample  not  only  to  meet  the  present  re- 
(luirements  of  commerce  but  also  for  many  years 
to  come.  A  navigable  channel  of  smaller  di- 
mensions than  those  proposed,  only  sufficient  for 
present  needs,  can  be  constructed  for  a  lesser 
sum  if  deemed  expedient. 

We  have  the  honor  to  be.  Sir, 

Your  obedient  servants, 

J.  G.  Walker, 
Eear- Admiral,  U.  S.  Navy, 

President  of  Commission. 

Lewis  M.  Haupt, 
Civil  Engineer,  Member. 

In  appending  my  signature  to  this  report,  I 
desire  to  state  that  I  concur  generally  with  the 
views  expressed,  but  my  estimate  of  the  cost  is 
$134,818,308. 

Peter  C.  Hains, 
Colonel,  U.  S.  Corps  of  Engineers,  Member. 


APPENDIX  I 


REPORT  OF  E.  S.  WHEELER 


CHIEF  ENGINEER 


CONTENTS 

Field  Work. 

Organization  and  Ingtnictions  to  Parties 51 

Results  aecomplishecl   52 

Topography  axd  Physics. 

General  Discussion .  54 

South  of  the  San  Juan  River 54 

North  of  the  San  Juan  River 55 

Lake  Nicaragua  to  the  Pacific 56 

Lake  Nicaragua   57 

Earthquakes    58 

San  Juan  River 58 

Volume  and  Tributaries 59 

Character  of  Bed  of  River 60 

Delta  Plain 61 

Sand  Movement 61 

Location. 

The  Canalization  of  the  Lower  San  Juan 62 

The  Canalization  of  the  Upper  San  Juan 63 

Fluctuations  in  the  Lake  Level 64 

Grade    68 

Additional  AVaste-ways 68 

Estimates. 

Nomenclature  of  Routes 70 

Unite  Prices 70 

Prices  for  the  East  Side 72 

Prices  for  the  AVest  Side 72 

Maritime  Canal  Co.'s  Proposed  Canal 72 

Menocal  Route,  Variant  1 73 

Lull  Route,  Variant  1 75 

Various  Routes,  Sarapiqui  Ridge  to  Caribbean  Sea 76 

Locks 78 

Various  Estimates    78 

Comparison  of  Estimates 79 

Route  with  One  Dam 80 

Route  with  Three  Dams 81 

The  100-ft.  Canal 83 

Value  of  Estimates 84 

4 


APPENDIX  I 


Washington,  D.  C. 

Rear-Admiral  J.  G.  Walker,  U.  S.  Navy, 
President  Nicaragua  Canal  Commission, 
Washington,  D.  C. 

Sir: — I  have  the  honor  to  submit  the  follow- 
ing report  of  operations  connected  with  the 
Nicaragua  Canal  Commission: 

The  expedition  sailed  from  New  York  De- 
cember 5,  1897,  on  the  U.  S.  Gimboat  "  New- 
port." There  were  on  board,  the  Commissioners 
and  sixty-nine  employes.  The  expedition  landed 
at  Greytown  December  18.  On  the  21st 
I  received  your  instructions  to  "  take  charge  of 
the  field  work  and  direct  the  operations  of  the 
various  parties." 

The  force  was  divided  into  eight  parties  with 
the  following  organization  and  instructions: 

Dr.  C.  W.  Hayes,  from  the  U.  S.  Geological 
Survey,  was  directed  to  take  charge  of  the  geo- 
logical work,  including  the  earth  and  rock  bor- 
ings. There  were  assigned  to  him  the  following 
assistants: 

Ignatius  O'lleardon,      Moriz  Bernstein, 
Ilarrv  Spence,  W.  E.  Herbert, 

P.  Tiemey,  E.  F.  Fischer, 

T.  J.  H.  Archambault,  E.  P.  Humphrey. 

Mr.  A.  P.  Davis,  also  from  the  U.  S.  Geo- 
logical Sur\'ey,  was  directed  to  take  charge  of 
the  hydrology  and  meteorology.  There  were 
assigned  to  him  the  following  assistants: 


R.  C.  Wheeler, 
D.  H.  Baldwin, 
W.  M.  Barton, 
F.  C.  Green, 
H.  S.  Reed, 
W.  W.  Schlecht, 


G.  P.  Philip, 
H.  W.  Miller, 
G.  R.  Wadleigh, 
R.  Breese, 
Neil  P.  Leary. 


Mr.  J.  W.  G.  Walker  was  directed  to  make  a 
topographical  survey  of  the  west  side.  The  fol- 
lowing assistants  were  assigned  to  him: 


E.  B.  Harden, 
M.  A.  Coroalles, 
H.  C.  Hurd, 
C.  P.  E.  Peugnet, 
O.  B.  Powell, 


L.  R.  Lee, 
J.  A.  Bull, 
P.  H.  Belknap, 
J.  D.  Forster. 


Mr.  George  W.  Brown  was  directed  to  make 
a  survey  of  the  San  Juan  river,  beginning  at 
Lake  Nicaragua.  The  following  assistants  were 
assigned  to  him: 


S.  S.  Evans, 
C.  L.  Hammond, 
Lester  Bernstein, 
F.  R.  Torrington, 


E.  G.  Nicewamer, 
Thaddeus  Merriman, 
G.  H.  AVilliams. 


Mr.  H.  H.  Trundle  was  directed  to  make  a 
survey  of  the  Canal  Company's  route  from  Grey- 
town  to  Ochoa.  The  following  assistants  were 
assigned  to  him: 

A.  J.  Norris, 
L.  F.  McNeil, 
P.  J.  Brune, 


W.  A.  Smith, 
Dion  Martinez. 


52 


NICARAGUA  CANAL  COMMISSION 


Mr.  Boyd  Ehle  was  directed  to  make  a  survey 
for  a  dam  at  Tambor  Grande  and  an  embank- 
ment southward  to  the  Costa  Riean  highland. 
The  following  assistants  were  assigned  to  him: 

O.  A.  F.  SaalVve,        E.  G.  Heyl, 
L.  S.  Snyder,  '  T.  F.  Boltz. 

J.  C.  Elson, 

Mr.  Andrew^  Onderdonk  was  directed  to  make 
a  survey  of  the  San  Juan  river  beginning  at 
Greytown.  The  following  assistants  were  as- 
signed to  him: 

W.  G.  Fitzgerald,      W.  D.  Thomas, 
R.  N.  Begien,  John  Carmichael, 

L.  E.  Lannan,  A.  V.  Montes. 

Messrs.  F.  L.  Stuart  and  Stephen  Harris  were 
directed  to  run  separate  lines  of  precise  levels 
from  the  Caribbean  sea  to  the  Pacific  ocean. 
The  following  assistants  were  assigned  to  them: 

J.  O.  Jones,  J.  A.  Mitchell, 

R.  B.  Post,  G.  F.  Seymour, 

Sherwood  Wilson,      L.  W.  Mohun. 

Mr.  F.  P.  Davis  was  directed  to  build  a  line  of 
camps  along  the  Canal  Company's  route  from 
Greytown  to  Ochoa.  Mr.  George  J.  Smart  was 
assigned  to  him  as  an  assistant. 

Mr.  H.  C.  Miller  was  assigned  to  the  Chief 
Engineer  as  First  Assistant. 

Mr.  J.  Crowninshield  was  given  charge  of 
supplies  and  warehouse  at  Greytown.  He  was 
assisted  by  Mr.  J.  H.  Barnard. 

The  following  gentlemen  were  sent  out  from 
the  United  States  later  and  were  distributed 
among  the  field  parties  on  their  arrival: 

C.  H.  Stockton,  H.  W.  Durham, 

H.  C.  C.  Shute,  J.  C.  Taylor, 

R.  Morrin,  H.  E.  Anschutz, 

John  Stockton,  L.  Hankins, 

H.  F.  Collins,  A.  S.  Miller. 


The  following  gentlemen  were  employed  in 
Nicaragua  and  distributed  among  the  parties: 

A.  L.  Scott,  J.  A.  Austin, 

Alfred  Ahrling,  A.  E.  L.  Pain, 

George  Challice,  Fred.  Davis, 

H.  E.  Webb,  E.  T.  Vargas, 

F.  H.  Davis,  F.  D.  Glennv. 
Charles  Hayman, 

Mr.  Brown  was  recalled  to  the  United  States 
shortly  after  he  began  work.  Mr.  Stuart  was 
put  in  charge  of  his  party  and  Mr.  Harris  took 
entire  charge  of  the  precise  leveling. 

Late  in  the  season  a  new  topographical  party 
was  organized  and  Mr.  Martinez  put  in  charge 
of  it;  after  one  month  he  was  replaced  by  Mr. 
Evans.  There  were  no  other  changes  among 
chiefs  of  parties,  though  the  exigencies  of  field 
work  made  many  changes  necessary  among  the 
subordinate  members. 

The  several  parties  completed  the  field  work 
assigned  them  as  follows:  Mr.  Boyd  Ehle  in 
August,  1898;  Messrs.  Miller,  Onderdonk, 
Trundle  and  the  Chief  Engineer  returned  to  the 
United  States  in  September;  Messrs.  Walker 
and  Hayes  in  October;  Mr.  Harris  in  November; 
Mr.  Stuart  in  December;  and  Mr.  Evans  in  Feb- 
ruary, 1899.   " 

Mr.  A.  P.  Davis  returned  in  October,  1898, 
leaving  his  party  in  the  field  under  the  charge 
of  Mr.  Hurd,  who  still  remains  in  Nicaragua. 

The  work  done  and  the  results  obtained  by 
each  of  the  parties  are  given  in  detail  in  the 
attached  appendices. 

A  brief  and  general  outline  of  the  aggregate 
results  is  as  follows:  The  geology  of  the  coun- 
try has  been  sufficiently  developed  so  that  a 
trustw^orthy  geological  map  of  the  Nicaraguan 
valley  has  been  made.  The  material  along  the 
line  of  the  various  canal  locations  has  been  clas- 
sified with  sufficient  accuracy  for  a  preliminary 


APPENDIX   I.— REPORT  OP  THE   CHIEF  ENGINEER 


53 


estimate.  Earthquakes  and  other  seismic  dis- 
turbances have  been  investigated  with  reassuring 
residts.  Tlie  rainfall  has  been  measured  con- 
tinuouslv  for  more  than  a  vear  at  twelve  dif- 
ferent  stations.  The  discharge  of  all  important 
streams  in  the  entire  drainage  basin  has  been 
measured,  both  at  high  and  low  water,  and  the 
amoimt  of  sediment  transported  by  them  deter- 
mined. Evaporation  obser\^ations  have  been 
made  at  different  places. 

The  probable  maximum  discharge  of  all  im- 
portant streams  has  been  deduced  from  their 
flood-plains  and  such  old  records  as  were  avail- 
able. 

The  fluctuations  of  Lake  Nicaragua,  its  evap- 
oration, inflow  and  outflow  have  been  continu- 
ously observed  for  more  than  a  year.  Their 
maximum  values  have  been  deduced  flx)m  the 
elevation  of  flood-plains  and  lake  beaches,  and 
from  former  observations.  A  similar  study  has 
been  made  of  Lake  Managua.  The  possibility 
of  diverting  certain  streams  into  Lake  Managua 
has  been  investigated  and  the  cost  estimated. 

On  the  west  side  a  topographical  survey  has 
been  made  of  the  vallevs  of  the  Rio  Grande 
and  the  Lajas  and  the  connecting  pass  betw^een 
their  headwaters.  This  survey  has  been  made 
with  sufficient  minuteness  so  that  locations  and 
estimates  can  be  made  directly  from  the  map. 

A  topographical  survey  of  the  San  Juan  river 
has  been  made  from  the  lake  to  the  sea,  includ- 
ing all  of  its  distributiaries  and  the  lower  reaches 
of  its  principal  tributaries.  (The  hydrography 
between  the  lake  and  Castillo  was  done  by  Lieu- 
tenant Hanus  of  the  Xavy,  and  was  not  under 
my  charge.)  This  survey  has  been  made  with 
suflScient  accuracy  so  that  wherever  the  river 
is  canalized  the  location  of  the  channel  and  the 
estimate  of  material  can  be  made  directly  from 
the  map. 


Probable  dam  sites  have  been  more  minutely 
developed. 

A  survey  has  been  made  of  Lake  Nicaragua, 
showing  the  shore  line  and  soundings. 

An  outline  survey  has  been  made  of  Lake 
Managua. 

A  survev  has  been  made  for  a  dam  at  Tambor 
Grande  and  an  embankment  line  running  south- 
ward to  the  highlands  of  Costa  Rica. 

A  resurvey  has  been  made  of  the  Maritime 
Canal  Company's  proposed  route  from  Greytown 
to  Ochoa.  This  survey  has  been  made  with 
sufficient  detail  so  that  an  accurate  estimate  of 
the  amount  and  classification  of  material  can 
be  made.  Surveys  for  a  canal  location  have 
beeif  made  from  the  mouth  of  the  San  Carlos 
river  to  Greytown.  From  the  source  of  the 
San  Juanillo  to  the  sea  three  different  lines  have 
been  run.  All  of  these  survevs  have  been  made 
with  sufficient  accuracy  for  an  estimate  along 
the  lines  themselves,  and  in  most  places  the 
topography  has  been  so  well  determined  that 
new  locations  and  estimates  can  be  made  from 
the  map. 

An  investigation  has  been  made  of  the  move- 
ment of  sand  along  the  shore  of  the  Caribbean 
sea  between  Port  Limon  and  Monkey  Point. 

A  duplicate  line  of  precise  levels  has  been 
run  from  Greytown  to  Brito.  Tide  gages  have 
been  read  for  several  months  at  both  places,  so 
that  the  difference  in  the  elevation  of  the  two 
oceans  is  quite  accurately  known. 

In  addition,  hydrographical  surveys  of  the 
coast  in  the  vicinity  of  Greytown  and  Brito 
were  made  from  the  U.  S.  Gunboats  "  New- 
port "  and  "  Alert."  This  work  was  not  under 
my  charge. 

The  aggregate  results  of  this  field  work,  when 
combined  with  the  results  of  previous  canal 
surveys,  together  with  all  other  existing  data,  are 


54 


NICARAGUA  CANAL  COMMISSION 


sufficient  to  sharply  define  the  limits  of  the 
"  canal  region  "  and  to  present  the  important 
physical  features  of  this  region  which  relate 
to  canal  construction. 

The  limits  of  the  canal  region  and  its  salient 
physical  features  will  first  be  presented. 

TOPOGEAPHY   AND  PllVSICS. 

The  following  discussion  of  the  topography 
and  physics  of  the  Nicaraguan  valley  is  for 
the  purpose  of  determining,  first,  the  limits  of 
the  canal  region;  and,  second,  such  physical 
features  of  this  region  as  relate  to  canal  con- 
struction. 

Much  of  the  data  in  this  discussion  is  tftken 
from  the  attached  appendices.  The  geology 
is  derived  entirely  from  the  report  of  Dr.  C. 
W.  Hayes,  the  hydrology  from  the  report  of 
Mr.  A.  P.  Davis  and  the  topography,  hydro- 
graphy, sand  movement,  etc.,  from  the  reports 
of  the  assistant  engineers. 

By  the  term  "  canal  region  "  is  meant  the 
region  in  which  a  canal  may  be  built  at  a  cost 
so  much  less  than  elsewhere  that  no  other  lo- 
cality need  be  considered.  Professor  Keasbey 
has  termed  this  "  the  region  of  comparative  fea- 
sibility." 

It  is  assumed,  without  discussion  here,  that 
no  canal  route  is  practicable  or  need  be  consid- 
ered that  does  not  pass  through  Lake  Nicaragua 
and  use  it  for  its  feeder  and  summit  level. 

The  canal  region  is  shown  on  Map  No.  2  in 
red.  It  will  be  seen  to  be  a  very  narrow  strip 
for  two-thirds  of  its  length.  In  the  remaining 
third  it  expands  to  a  width  of  fifteen  or  twenty 
miles.  All  of  the  proposed  canal  routes  lie 
within  this  region,  and  it  will  be  sho^vn  that  none 
outside  of  it  are  as  good.  (If  there  were  a  com- 
plete and  accurate  topographical  map  of  the  en- 
tire country,  this  fact  would  become  apparent 


by  a  simple  reference  to  it.  In  the  absence 
of  special  knowledge  derivable  from  such  a 
source,  evidence  must  come  from  the  considera- 
tion of  general  laws  sufficiently  convincing  to 
those  familiar  with  the  conditions.) 

For  convenience,  the  country  bordering  on  the 
canal  region  will  be  considered  in  three  parts. 
The  first  part  lies  south  of  the  San  Juan  river 
and  is  limited  on  the  south  bv  the  foot-hills  of 
the  Costa  Rican  mountains. 

The  second  part  lies  north  of  the  San  Juan 
river  and  between  Lake  Nicaragua  and  the 
Caribbean  sea. 

The  third  part  is  the  narrow  strip  of  land  ly- 
ing between  Lake  Nicaragua  and  the  Pacific 
ocean. 

In  the  present  discussion  it  is  not  intended  to 
give  a  complete  analysis  of  the  topography  and 
physics  of  the  entire  Nicaraguan  valley;  only 
such  points  will  be  considered  as  relate  to  the 
location  of  a  canal  and  tend  to  permit  or  pre- 
vent its  construction. 

A  reference  to  the  accompanying  map  will 
show^  that  the  portion  of  the  Nicaraguan  valley 
which  lies  between  the  San  Juan  river  and  the 
foot-hills  of  the  Costa  Rican  mountains  is 
crossed  by  a  number  of  rivers,  some  of  them  of 
considerable  size.  The  San  Carlos  is  the  largest. 
The  Sarapiqui,  Frio  and  Poco  Sol  are  streams 
of  considerable  size.  An  inspection  of  the  map 
shows  that  these  streams  have  their  sources  in 
the  Costa  Rican  mountains  and  flow  in  a  north- 
erly direction  across  the  plain  into  the  San  Juan 
river.  Thev  have  a  swift  current  but  no  falls 
or  great  rapids  below  the  foot  of  the  mountains. 

An  examination  of  the  map  shows  that  a  canal 
location  from  the  Caribbean  sea  to  Lake  Nica- 
ragua, south  of  the  San  Juan  river,  would  cross 
all  of  those  streams.  This  would  make  its  con- 
struction practically  an  impossibility.     The  ex- 


APPENDIX  I.— REPORT  OF  THE   CHIEF  ENGINEER 


55 


istence  of  these  streams  is  deemed  entirely  suf- 
ficient to  exclude  from  the  canal  region  all  that 
part  of  the  Nicaraguan  valley  lying  south  of 
the  San  Juan  river.  The  southern  boundary 
of  the  canal  region  on  the  eastern  side  is  then 
the  south  banks  of  the  San  Juan  and  Colorado 
rivers.  Before  leaving  the  discussion  of  the 
flouthem  part  of  the  valley  a  few  points  will  be 
mentioned  that  relate  to  and  assist  in  elucidating 
the  topography  north  of  the  river.  An  inspec- 
tion of  Map  No.  1,  Sheet  Iso.  2,  shows  that  the 
material  of  this  southern  part  of  the  Nicaraguan 
valley  is  volcanic  ejecta  and  alluvium.  The 
alluvium  is  found  at  the  eastern  and  western  ends 
of  the  valley,  where  it  borders  on  the  Caribbean 
«ea  and  Lake  Nicaragua.  The  volcanic  material 
was  ejected  from  the  line  of  Costa  Rican  vol- 
canoes and  flowed  down  to  the  northward,  until 
it  met  the  older  plain  which  slopes  from  the 
north,  southward.  A  reference  to  Map  No.  1, 
Sheet  No.  2,  will  show  that  the  San  Juan  river 
•does  not  exactly  follow  the  junction  of  these  two 
plains  but  cuts  through  the  southern  portion  of 
the  northern  plain,  leaving  a  few  of  the  older 
hills  south  of  the  San  Juan.  Of  these  hills, 
those  at  the  junction  of  the  San  Carlos  with  the 
San  Juan  are  most  conspicuous,  having  an  esti- 
mated height  of  more  than  1100  feet. 

The  second  part  is  the  region  lying  north  of 
the  San  Juan  river  and  between  Lake  Nicaragua 
and  the  Caribbean  sea.  A  reference  to  Map 
No.  1  will  show  by  the  sources  of  the  streams 
that  there  is  a  crest-line  or  divide  which  is 
nearly  parallel  to  the  eastern  shore  of  Lake  Nica- 
ragua and  about  twenty  miles  distant.  If  the 
narrow  strip  of  land  between  Lake  Nicaragua 
and  the  Pacific  were  removed,  this  crest  would 
become  the  Continental  Divide.  This  was  prob- 
ably the  case  until  quite  recent  geologic  times, 
and  the  shape  of  the  Pacific  shore,  before  the  •out- 


break of  the  Nicaraguan  volcanoes,  was  some- 
what as  shown  on  Plate  No.  11,  Appendix  11. 
This  is  mentioned  here  because  the  country  be- 
tween Lake  Nicaragua  and  the  Caribbean  sea  is 
much  older  than  the  Nicaraguan  volcanoes, 
and  much  of  its  surface  configuration  was  made 
before  Lake  Nicaragua  was  cut  off  from  the 
sea.  With  this  condition  in  mind  it  becomes 
easier  to  understand  certain  features  of  the 
topography.  The  streams  east  of  the  Divide 
run  in  an  easterly  direction  to  the  Caribbean 
sea;  those  west  of  the  Divide  run  in  a  south- 
westerly direction  to  Lake  Nicaragua.  It  will 
be  observed  that  the  direction  of  this  drainage 
is  about  parallel  to  the  course  of  the  San  Juan 
and  at  right  angles  to  that  of  the  country  south 
of  the  river.  This  is  an  indication  that  the  two 
plains  north  and  south  of  the  river  are  essen- 
tially dissimilar  and  that  they  were  formed  at 
different  times  and  by  different  causes. 

It  is  also  very  fortunate  for  canal  purposes 
that  no  large  rivers  flow  into  the  San  Juan  from 
the  north.  The  importance  of  this  fact  will 
be  referred  to  later.  In  addition  to  the  two 
plains  which  slope  to  the  sea  and  the  lake,  there 
is  a  third  important  line  of  descent  not  shown 
on  the  map,  and  this  is  the  Divide  itself.  In  the 
northern  part  of  Nicaragua  the  summits  along 
this  crest-line  reach  an  elevation  of  five  to  seven 
thousand  feet.  Following  the  Divide  south- 
ward, its  elevation  steadily  diminishes  until  it 
crosses  the  San  Juan  in  the  vicinity  of  Castillo 
and  is  soon  lost  in  the  Costa  Rican  plain. 

Referring  again  to  the  map,  it  will  be  seen 
that  the  shortest  distance  between  Lake  Nica- 
ragua and  the  Caribbean  sea  is  less  than  sixty 
miles,  while  the  canal  route  is  about  one  hundred 
miles.  It  will  also  be  seen  that  the  streams  and 
consequently  the  valley  lie  in  a  generally  east 
and   west  direction,   or  favorable   for  a   canal 


56 


NICARAGUA  CANAL  COMMISSION 


route.     The  question,  then,  whether  or  not  this 
shorter  route  can  be  utilized  becomes  an  impor- 
tant one;  and  if  this  narrowest  part  of  the  isth- 
mus is  excluded  from  the  canal  region  it  should 
be  for  a  sufficient  reason.     That  reason  is  the 
elevation  of  the  dividing  ridge  between  the  lake 
and  the  sea.     The  proof  that  there  are  no  low 
passes  through  this  divide  is  quite  conclusive. 
Some  of  the  evidence  is  as  follows:     When  the 
San  Juan  first  overtopped  and  broke  through 
the  pass  at  Castillo,  it  was  at  least  fifty  feet 
higher  than  it  is  now.     The  evidence  that  it 
has  been  eroded  and  cut  down  fifty  feet  is  ample. 
Since  the  water  would  find  the  lowest  pass,  it  is 
evident,  therefore,  that  there  is  no  other  pass 
that  is  not  at  least  fifty  feet  higher  than  the 
present  river  valley.     Again,  it  has  been  men- 
tioned that  in  the  northern  part  of  Nicaragua 
the  summits  of  this  ridge  are  seven  thousand  feet 
high,  while  the  intermediate  valleys  have  ele- 
vations of  two  and  three  thousand  feet.     Both 
the  summits  and  the  valleys  slope  quite  uni- 
formlv  to  the  southeast  until  both  are  lost  in  the 
Costa  Rican  plain.     The  rate  of  this  descent  is 
about  ten  feet  per  mile  for  the  valleys.     There- 
fore, if  this  ridge  be  followed  from  Castillo  in  a 
northwesterly  direction,  the  average  height  of 
its  valleys  or  passes  will  increase  at  the  rate  of 
about  one  hundred  feet  in  ten  miles.     So  far  as 
observations  go,  this  seems  to  be  the  case.     Per- 
haps the  most  convincing  proof  of  the  consider- 
able elevation  of  this  ridge  is  the  actual  observa- 
tions that  have  been  made.     In  this  countrv, 
without  roads,  the  streams  are  used  as  thorough- 
fares.     All   of    these   streams   are   continuallv 
traveled  by  rubber  hunters  and  explorers  of  all 
kinds.     The  invariable  report  of  these  men  is 
that  for  the  first  five  or  ten  miles  from  the  sea 
the  current  is  sluggish;  after  that  it  is  found  to 
be  rapid  all  the  way  to  its  source,  indicating  that 


all  of  the  larger  streams  have  their  sources  in 
elevations  of  not  less  than  three  or  four  hun- 
dred feet.  The  small  streams  that  flow  into 
the  San  Juan  from  the  north  are  rapid  in  their 
upper  reaches  and  soon  rise  to  a  considerable  ele- 
vation. Again,  the  summit  of  this  ridge  when 
seen  from  a  distance,  shows  a  uniform  slope  to 
the  southward,  but  with  no  indication  of  notches 
or  low  passes  in  it.  The  cumulative  evidence 
of  the  height  and  continuity  of  this  ridge  is  suf- 
ficient to  exclude  from  the  canal  region  all  of 
that  country  lying  north  of  the  San  Juan,  ex- 
cept the  narrow  valley  of  the  river  itself,  from 
the  lake  to  the  San  Juanillo  and  the  broader 
delta  plain  from  there  to  the  sea.  The  north- 
em  boundary  of  the  canal  region  on  the  east  side 
is,  therefore,  as  shown  in  Map  Xo.  2. 

The  third  section  is  the  narrow  strip  of  land 
lying  between  Lake  Nicaragua  and  the  Pacific 
ocean.  It  will  be  seen  that  the  canal  region 
here  occupies  the  valleys  of  the  Rio  Grande  and 
the  Lajas.  The  route  is  seventeen  miles  long. 
The  greatest  elevation  is  about  forty-five  feet 
above  Lake  Nicaragua.  This  country  is  tra- 
versed by  roads  in  every  direction.  It  is  quite 
accurately  mapped.  All  the  lower  passes  have 
been  examined,  and  the  evidence  is  complete  and 
convincing  that  the  route  chosen  is  through 
much  the  lowest  pass  between  the  lake  and  the 
ocean,  and  that  the  cost  is  much  less  here  than 
by  any  other  route.  This  conclusion  has  been 
reached  through  actual  surveys  and  observa- 
tions. The  boundaries  of  the  canal  region  on 
the  west  side  are,  therefore,  as  shown  on  the 
map. 

The  physical  reasons  w^hich  limit  the  canal 
region  may  be  briefly  summarized  as  follows: 
On  the  east  side  the  country  south  of  the  San 
Juan  river  is  excluded  by  the  large  rivers  which 
cross  it.     The  coimtrj-  north  of  the  valley  of  the 


APPENDIX   I.— REPORT   OF  THE   CHIEF  ENGINEER 


57 


San  Juan  river  is  excluded  by  the  range  of  high 
hills  which  crosses  it  in  a  northwesterly  and 
southeasterly  direction.  This  leaves  for  the 
canal  region  on  the  east  side  only  the  narrow 
valley  and  delta  plain  of  the  San  Juan  river. 

On  the  west  side  the  countrv  both  north  and 
south  of  the  valleys  of  the  Rio  Grande  and 
Lajas  is  excluded  by  the  range  of  high  hills 
which  form  the  Continental  Divide. 

The  character  and  importance  of  this  region 
may  be  illustrated  and  emphasized  by  the  state- 
ment that  it  is  believed  that  anv  canal  location 
whollv  outside  of  it  would  cost  at  least  five  times 
as  much  as  a  similar  canal  properly  located 
within  it. 

The  boundaries  of  the  canal  region  having 
thus  been  determined,  the  physical  features  of 
the  region  itself  will  next  be  considered. 

On  the  west  side  it  is  made  up  of  the  valleys  of 
two  small  streams  and  the  low  pass  connecting 
them.  The  Rio  Grande  flows  into  the  Pacific. 
Its  observed  maximum  discharge  is  2975  cubic 
feet  per  second.  Its  minimum  discharge  is  al- 
most nothing.  This  river  has,  in  former  times, 
been  much  larger  than  now  and  has  worn  a  cor- 
responding channel.  This  old  channel  has  been 
silted  up  and  the  present  smaller  river  has  cut 
its  way  through  the  silt,  using  only  a  portion  of 
the  old  river  bed.  It  is  probable  that  this  old 
river  was  the  outlet  for  a  time  of  Lake  Nica- 
ragua. Eventually  the  San.  Juan  river  cut  back 
through  the  Divide  at  Castillo  and  turned  the 
drainage  of  the  lake  to  the  Caribbean  sea. 
Whatever  the  cause  mav  have  been,  the  old 
river  bed  is  here  and  diminishes  to  a  considerable 
extent  the  rock-cutting  in  the  channel.  The 
probability  that  the  outlet  of  Lake  Nicaragua 
was  at  one  time  on  the  Pacific  side  is  of  interest 
and  some  importance  and  will  be  referred  to 
later.     The   Rio  Grande  at  times  carries  con- 


siderable sediment.  It  shows,  however,  no  signs 
of  a  delta.  The  coast  in  the  vicinity  of  its 
mouth  is  defended  by  a  series  of  rocky  promon- 
tories. Between  them  the  sand  and  alluvium  are 
shaped  by  the  sea  into  a  slightly  concave  shore 
line,  which  appears  to  be  practically  permanent. 
The  shore  where  the  Rio  Grande  discharges  into 
the  sea  shows  no  changes  from  the  earliest  maps. 
The  sea  floor  is  quite  steep,  the  seven-fathom 
cun^e  being  about  1300  feet  from  the  shore. 
The  tides  have  a  range  of  about  nine  feet. 

The  Lajas  is  a  small  stream  flowing  into  Lake 
Nicaragua.  It  carries  some  sediment.  The 
bottom  of  the  lake  at  the  mouth  of  this  stream  is 
quite  steep,  the  six-fathom  curve  being  about 
4000  feet  from  the  shore. 

The  first  seven  miles  of  the  canal  region  on 
the  west  side,  beginning  at  Brito  and  going  east- 
ward, are  the  flood-plain  of  the  Rio  Grande. 
This  plain  is  quite  irregular  in  shape.  It  has  a 
seaward  slope  of  about  ten  feet  to  the  mile.  The 
alluvium  of  which  it  is  composed  varies  from 
forty  to  one  hundred  feet  in  depth.  It  is  partly 
imder  cultivation  but  generally  wooded.  It  is 
the  most  fertile  and  beautiful  valley  in  the  canal 
region.  From  the  head  of  this  valley  to  Lake 
Nicaragua  is  about  ten  miles.  The  excavation 
for  the  canal  here  is  almost  entirely  through 
rock.  The  average  thickness  of  the  earth  on 
the  rock  is  about  six  feet.  The  rock  is  shale 
and  sandstone,  much  broken  and  easy  to  exca- 
vate. This  part  of  the  canal  region  is  quite  nar- 
row, the  hills  approaching  closely  on  each  side. 

Lake  Nicaragua. 

This  lake  is  about  one  hundred  miles  long 
and  fortv-five  miles  wide.  It  has  an  area  of 
about  3000  square  miles.  Its  greatest  depth  is 
two  hundred  feet.  It  is  about  one-third  the  size 
of  Lake  Erie.     The  length  of  the  sailing  line, 


58 


NICARAGUA  CANAL  COMMISSION 


between  the  points  where  the  canal  enters  and 
leaves  it,  is  about  seventy  miles.  Its  total  drain- 
age area  is  12,900  square  miles.  Its  inflow  dur- 
ing periods  of  great  rainfall  is  sometimes  suf- 
ficient to  raise  the  surface  six  inches  in  forty- 
eight  hours.  The  maximum  calculated  outflow 
is  50,000  cubic  feet  per  second.  Its  evapora- 
tion is  estimated  to  be  about  five  feet  annually. 
During  the  dry  season  the  evaporation  exceeds 
the  inflow.  During  exceptionally  dry  years  the 
evaporation  exceeds  the  inflow  for  the  entire 
year.  This  causes  considerable  fluctuation  in 
the  elevation  of  its  surface.  It  is  reported  as 
having  been  as  low  as  ninety-seven  feet  above 
sea  level  and  as  high  as  one  hundred  and  twelve. 
These  reports  or  traditions  are  somewhat  uncer- 
tain. It  is,  however,  reasonably  certain  that  it 
fluctuates  between  one  hundred  and  one  hundred 
and  ten  above  sea  level,  at  no  very  infrequent 
intervals.  Its  depth  along  the  proposed  sailing 
line  is  ample  except  for  thirteen  miles  on  the 
east  side.  Here  submarine  excavations  will  be 
necessary.  Borings  show  that  the  material  to 
be  excavated  is  silt. 

Earthquakes. 

Before  considering  the  east  side  some  of  the 
salient  facts  connected  with  earthquakes  will  be 
mentioned.  In  the  northwestern  part  of  Nica- 
ragua slight  earthquakes  are  frequent.  Scarcely 
a  month  passes  without  one  or  more  being  no- 
ticed. The  center  of  these  disturbances  is 
always  near  the  line  of  the  Nicaraguan  vol- 
canoes. The  line  of  volcanoes  begins  with  Ma- 
dera at  the  southern  end,  in  Lake  Nicaragua, 
and  terminates  with  Casiguina  at  the  northern 
end  near  the  Gulf  of  Fonseca.  This  country  is 
geologically  very  recent.  The  great  seismic  dis- 
turbance which  caused  this  upheaval  has  nearly 
passed.     Nearly  all  the  volcanoes  are  extinct; 


only  two  or  three  are*  still .  smoking.  It  is  be- 
lieved that  this  is  an  era  of  subsidence  and  that 
earthquakes  and  other  seismic  manifestations 
will  continue  to  grow  lighter  and  finally  cease 
altogether.  Again,  the  canal  route  is  entirely 
south  of  the  earthquake  area.  In  the  historic 
period  there  have  been  no  earthquakes  in  the 
canal  region  of  sufficient  violence  to  injure  canal 
structures.  It  is  believed  that  the  danger  from 
earthquakes  here  is  now  no  greater  than  in  any 
other  seacoast  region. 

East  Side. 

The  physical  features  of  the  east  side  will  next 
be  considered.  It  has  already  been  stated  that 
the  canal  region  is  only  the  narrow  San  Juan 
valley  and  its  broader  delta  plain.  The  con- 
trolling physical  feature  of  this  region  is  the  San 
Juan  river.  At  one  time  it  was  separated  into 
two  parts  by  the  Continental  Divide  crossing  at 
Castillo.  One  part  flowed  eastwardly  into  the 
Caribbean  sea  and  the  other  westwardly  into  the 
Pacific  ocean.  This  condition  was  so  recent 
that  many  of  its  topographic  and  hydrographic 
effects  still  remain,  some  of  them  having  an  im- 
portant bearing  upon  canal  work.  The  western 
branch  had  its  sources  west  of  Castillo  and  was 
formed  by  the  junction  of  the  Poco  Sol  and  the 
Savalos  rivers.  It  then  flowed  westwardly  and 
emptied  into  the  Pacific  ocean  near  where  Ma- 
dera now  stands.  An  inspection  of  the  map  of 
Lake  Nicaragua  shows  two  sections  of  this  old 
river  valley  not  yet  silted  up;  one  in  the  vicinity 
of  Madera  and  the  other  near  Solentiname.  This 
latter  will  be  utilized  for  canal  purposes.  It  will 
be  noticed  that  the  depth  of  this  submerged  river 
valley  is  considerably  below  sea  level,  showing 
that  at  the  time  it  was  formed  the  land  stood 
higher  than  now.  The  southern  end  of  Lake 
Nicaragua  has  been  so  silted  up  that  a  consid- 


APPENDIX  I— REPORT   OP  THE   CHIEF   ENGINEER 


59 


erable  portion  of  this  old  channel  is  concealed. 
Its  old  location  can,  however,  be  determined  by 
boring.  The  single  line  of  borings  between  the 
mouth  of  the  lake  and  Castillo  shows  it  in  many 
places.  It  is  probable  that  considerable  rock 
excavation  can  be  avoided  by  properly  develop- 
ing this  old  channel  and  following  it  with  the 
canal,  rather  than  the  present  river  bed.  An  in- 
spection of  the  map  shows  that  all  the  tributaries 
of  the  San  Juan  river  west  of  Castillo  still  run 
westwardly  in  their  lower  reaches  as  they  did 
when  they  ran  to  the  Pacific  ocean.  The  east- 
ern branch  had  its  sources  on  the  east  of  Castillo 
and  was  formed  by  the  junction  of  the  Bartolo 
with  other  small  streams  and  flowed  eastwardly 
to  the  Caribbean  sea  in  nearly  the  same  channel 
that  it  now  occupies;  except  perhaps  through  the 
delta  plain.  Its  bed  has  been  developed  by 
borings  in  a  number  of  places.  Its  seaward  slope 
seems  to  have  been  quite  uniform  with  a  gra- 
dient of  about  four  feet  per  mile,  which  is  much 
steeper  than  the  present  river  bed.  The  Ma- 
chuca  rapids  must  have  had  a  fall  of  about  fifty 
feet  more  than  at  present,  because  immediately 
below  Machuca  the  bottom  of  the  old  river  bed 
is  found  to  be  about  fiftv  feet  lower  than  at 
Machuca.  There  still  remains  one  section  of 
this  old  channel  that  has  not  yet  been  completely 
silted  up.  This  is  between  Machuca  and  the 
mouth  of  the  San  Carlos  river.  This  is  called 
Aguas  Muertas,  or  dead  waters.  There  are 
soundings  in  this  reach  that  go  below  sea  level. 
This  channel,  like  the  one  on  the  Pacific  slope, 
is  very  deeply  worn,  thus  indicating  again  that 
the  land  must  have  stood  higher  at  that  time 
than  at  present.  The  tributaries  to  this  branch 
turn  eastwardlv  in  their  lower  reaches.  The 
present  San  Juan  has,  therefore,  two  sets  of 
tributaries,  those  of  the  lower  half,  flowing  east- 
wardly in  the  normal  direction,  and  those  of  the 


upper  half,  flowing  westwardly  or  opposite  to 
the  direction  of  the  main  stream. 

Volume  and  Tributaries. 

The  San  Juan  river  as  it  is  at  present  is  about 
one  hundred  and  twenty  miles  long.  Where  it 
leaves  Lake  Nicaragua  its  estimated  maximum 
discharge  is  fifty  thousand  cubic  feet  per  second; 
above  the  mouth  of  the  San  Carlos  it  is  one  hun- 
dred thousand.  When  it  enters  the  Caribbean 
sea  the  estimated  maximum  discharge  of  all  its 
distributaries  is  three  hundred  thousand  cubic 
feet  per  second.  This  makes  the  upper  San 
Juan  river  a  stream  comparable  in  maximum  vol- 
ume with  the  St.  Mary's  river  or  the  Potomac 
at  the  head  of  tidewater,  and  the  lower  San  Juan 
comparable  with  Niagara  or  the  Susquehanna  at 
Harrisburg.  The  two  principal  tributaries  are 
the  San  Carlos  with  an  estimated  maximum  dis- 
charge of  one  hundred  thousand  cubic  feet  per 
second  and  the  Sarapiqui  with  an  estimated 
maximum  discharge  of  sixty  thousand  cubic  feet 
per  second.  The  reason  that  so  large  a  river  is 
possible  in  so  small  a  drainage  basin  is  the  enor- 
mous rainfall.  In  the  country  between  Lake 
Nicaragua  and  the  Caribbean  sea  the  average 
annual  rainfall  is  about  fifteen  feet.  The  aver- 
age annual  evaporation  from  the  land  surface  is 
about  four  feet.  This  leaves  eleven  feet  for 
run-off  or  about  eleven  times  as  deep  as  the  aver- 
age run-off  in  the  United  States  east  of  the 
Mississippi.  Again,  the  valley  is  so  small  that 
flood-waters  are  precipitated  very  quickly  into 
the  main  river. 

When  the  San  Juan  first  leaves  the  lake  it  is 
almost  wholly  free  from  sediment,  but  very  little 
is  added  above  the  San  Carlos.  This  is  evident 
from  the  fact  that  the  deep  channel  through  the 
Aguas  Muertas  has  not  yet  been  silted  up.  The 
San  Carlos  carries  large  quantities  of  sand,  and 


60 


NICARAGUA  CANAL  COMMISSION 


from  its  junction  to  the  sea  the  San  Juan  is 
heavily  laden  with  sand.  At  the  head  of  the 
delta  plain  the  San  Juan  separates  into  several 
distributaries.  The  Colorado  is  the  principal 
stream  and  carries  perhaps  four-fifths  of  the 
water.  The  lower  San  Juan  is  next  in  im- 
portance. It  has  a  small  branch  called  the 
Tauro.  The  San  Juanillo  leaves  the  main  river 
and,  after  a  circuitous  curve  of  about  tw^enty 
miles,  rejoins  it  again.  The  Cario  Bravo  is  a 
branch  of  the  Colorado.  The  Parado  is  a  small 
stream  that  leaves  the  lower  San  Juan  and  flows 
into  the  Agua  Dulce  lagoon. 

Character  of  Bed  of  River. 

From  the  lake  to  near  Castillo  the  river  bed 
to  a  depth  of  thirty  feet  or  more  is  earth,  being 
chiefly  silt,  sand  and  clay  that  has  been  deposited 
in  the  old  river  bed,  which  has  already  been  de- 
scribed and  which  was  much  deeper  than  the 
present  one  and  sloped  westwardly  to  the  Pacific 
ocean.  From  a  little  above  Castillo  to  a  little 
below  Machuca,  a  distance  of  about  fourteen 
miles,  the  river  flows  over  a  bed  of  sandstone 
rock  in  practically  the  same  channel  that  it  has 
always  followed.  This  part  of  the  river  has 
never  been  worn  down.  The  sandstone  has  re- 
sisted erosion  and  the  river  bed  here  is  the  same, 
or  probably  worn  a  little  deeper  than  it  was  be- 
fore the  drainage  of  Lake  Nicaragua  \tas  turned 
eastward.  This  is  the  only  river  section  in 
which  there  will  be,  for  canal  purposes,  any  con- 
siderable amount  of  rock  work.  Most  of  the 
rapids  occur  in  this  section.  There  is  a  fall 
of  thirty-seven  feet  in  fourteen  miles.  At  the 
foot  of  the  Machuca  rapids  the  sandstone  dis- 
appears. It  has  previously  been  mentioned  that 
the  upper  San  Juan  brings  no  sediment  from 
the  lake,  and  the  small  streams  that  flow  into  it 
carry  but  little.     This  is  believed  to  be  the  ex- 


planation as  to  why  this  portion  of  the  old  chan- 
nel still  remains.  The  San  Carlos  carries  a  large 
amount  of  sand,  so  that  from  its  mouth  to  the 
sea  the  old  channel  has  been  silted  up  and  the 
San  Juan  now  flow^s  over  a  sandv  bed  betw^een 
banks  of  sand. 

The  important  features  of  the  bed  of  the  San 
Juan    river   may    be    summarized    as   follows: 
From  the  lake  to  Toro  rapids  the  river  flows  in 
the  partially  silted  channel  of  an  older  stream 
that  formerlv  flowed  westwardlv  to  the  Pacific 
ocean.     From  Machuca  to  the  Caribbean,  the 
river  flows  in   the   deeply-worn   and   partially- 
silted  channel  of  an  older  stream  that  had  its 
source  near  Castillo  and  flowed  eastwardly  to 
the   Caribbean   sea.     Between    Toro    and    Ma- 
chuca the  river  flows  in  what  may  properly  be 
called  its  own  bed,  that  is,  the  earlier  streams 
that  flowed  through  this  section  were  so  small 
and  the  material  over  which  they  ran  so  hard, 
that  thev  left  no  traces  of  their  channel.     The 
great   amount   of  sediment    and    the   immense 
floods  below  the  San  Carlos  make  the  canaliza- 
tion of  this  part  of  the  San  Juan  very  difficult. 
Fortunately  the  topography  is  such  that  alterna- 
tives are  possible.     An  inspection  of  the  map 
shows  that  from  the  mouth  of  the  San  Carlos  to 
the  sea  no  large  streams  enter  the  San  Juan  from 
the  north.     The  largest  one  is  the  San  Francisco 
which  has  a  drainage  of  about  forty  square  miles. 
Its  greatest  observed  discharge  is  two  thousand 
cubic  feet  per  second.     Its  estimate'd  maximum 
discharge  is  four  thousand  cubic  feet  per  second. 
This  amount  of  water  is  not  so  great  that  it  can- 
not be  admitted  to  the  canal  and  passed  out 
again  through  sluices  without  serious  inconveni- 
ence.    There  are  some  hills  that  approach  close 
to  the  river  but  none  that  cannot  be  either  cut 
through  or  passed  around.    There  are,  therefore, 
no  serious  physical  objections  to  building  a  canal 


APPENDIX   I.— REPORT  OP  THE   CHIEF  ENGINEER 


61 


along  the  north  side  of  the  San  Juan  from  the 
lake  to  the  sea. 

Delta  Plaix. 

The  delta  plain  is  of  considerable  extent.  Its 
outlines  are  quite  accurately  shown  on  the  map. 
It  has  a  seaward  slope  of  about  one  and  one- 
half  feet  per  mile.  It  is  heavily  wooded  and 
for  the  most  part  marshy.  There  are  some  hills 
in  it,  mostly  between  Lake  Silico  and  the  Colo- 
rado river.  These  hills  are  much  older  than  the 
plain.  They  resemble  islands  in  a  sea  of  allu- 
vium. The  material  and  surface  of  the  delta 
plain  are  so  uniform  that  the  cost  per  mile  of 
building  a  canal  would  be  nearly  the  same  in 
any  part. 

Sand  Movement. 

After  the  sand  has  been  carried  to  the  sea 
by  the  streams  it  is  transported  by  wave  action 
along  the  shore.  The  observed  facts  concerning 
the  movement  of  sand  along  the  shore  in  the 
vicinity  of  Grey  town  harbor  are  as  follows: 
From  Port  Limon,  seventy  miles  south  of  Grey- 
town  to  Point  of  Rocks,  forty  miles  north  of 
Greytown,  the  shore  is  formed  of  a  coarse  black 
sand  of  volcanic  origin.  In  places  this  sand  is 
known  to  extend  two  or  three  miles  inland.  The 
hydrographic  map  of  the  coast  between  the  Colo- 
rado and  the  Indio  rivers  shows  that  it  extends 
seaward  to  between  the  seven-  and  eight-fathom 
curves.  Xone  is  shown  beyond  the  eight-fathom 
curve.  To  the  northwest  of  Grevtown  the 
amount  of  sand  along  the  shore  steadily  dimin- 
ishes, until  at  Point  of  Kocks  it  disappears  en- 
tirely. This  sand  is  at  present  being  brought 
to  the  sea  by  all  the  streams  having  their 
sources  in  the  Costa  Rican  mountains.  The 
Colorado  and  the  San  Juan  carry  considerable 
quantities  which  are  obtained  from  the  San 
Carlos  and  the  Sarapiqui.     The  streams  north 


of  the  San  Juan  do  not  carry  any.  A  consider- 
able amount  of  this  sand  stops  in  and  about 
Greytown  harbor.  This  quantity  has  been  com- 
puted by  Professor  Mitchell,  by  the  Board  of 
1895,  and  by  Professor  Haupt.  All  have  found 
it  to  be  about  seven  hundred  and  fifty  thousand 
cubic  yards  annually.  An  examination  of  old 
maps  shows  that  at  the  point  where  the  Maritime 
Canal  Company's  harlwr  is  located,  the  six-fath- 
om curve  has  been  pushed  seaward  at  an  average 
rate  of  seventy-five  feet  per  annum  since  1809. 
Dr.  Hayes  has  pointed  out  that  temporary 
harbors  have  been  formed  several  times  near 
where  GreytowTi  now  stands.  The  first  one  of 
these  was  Lake  Silico.  It  was  at  one  time  a 
sheltered  bay.  Some  of  the  hills  which  now 
surround  it  were  then  islands.  The  silt  and 
northward-moving  sea  drift  finally  shut  it  off 
from  the  sea.  Then  other  harbors  were  succes- 
sively formed  in  front  of  Lake  Silico.  The 
several  long  parallel  lagoons  still  show  the  sites 
of  these  harbors.  The  last  one,  which  has  been 
known  as  Greytown  harbor,  has  been  entirely 
formed  and  closed  within  the  historic  period. 
The  first  trustworthy  map  of  the  vicinity  was 
made  in  1809.  At  that  time  the  sand  spit  had 
pushed  out  from  harbor  head  %  about  three- 
quarters  of  a  mile.  If  its  rate  of  growth  or  ac- 
cretion before  that  time  had  been  the  same 
that  it  was  af tenvards,  it  must  have  begun  about 
the  middle  of  the  last  centurv.  In  1809  there 
was  a  small  but  deep  and  safe  harbor  behind  the 
sand  spit.  The  lengthening  of  this  sand  spit 
was  very  uniform,  imtil  in  1852  it  reached  the 
mainland,  and  the  harbor  of  Greytown  was  con- 
verted into  another  lagoon.  At  present  there 
are  no  definite  signs  of  the  beginning  of  another 
sand  spit.  It  may  or  may  not  be  that  the  form 
of  the  shore  is  now  such  that  this  process  will 
not  be  again  repeated.     The  littoral  current  off 


62 


NICARAGUA  CANAL  COMMISSION 


this  coast  is  for  the  most  part  southward.  On  the 
hydrographic  charts  it  is  so  marked  with  a  velo- 
city of  from  one  to  two  knots  per  hour.  During 
the  year  1898  it  ran  southward  about  eleven 
months.  When  the  trade  winds  were  mildest 
the  southerly  current  diminished  and  finally 
stopped  and  then  flowed  gently  northward  for 
about  one  month.  I  was  told  by  the  sailors  and 
fishermen  that  this  change  in  the  direction  of 
the  current  was  expected  by  them  each  year. 
An  inspection  of  the  map  shows  that  all  the 
streams  between  G  rev  town  and  Port  Limon  have 
at  their  mouths  sand  spits  which  are  turned 
northward.  The  Rio  Indio  north  of  Greytown 
has  a  sand  spit  now  turned  southward,  though 
formerly  it  seems  to  have  been  turned  to  the 
northward.  The  inferences  that  have  been 
drawn  from  the  preceding  data  are  as  follows: 
There  is  a  stream  of  sand  moving  northward 
along  the  coast  between  Port  Limon  and  Point 
of  Rocks.  It  is  confined  to  the  belt  between 
the  eight-fathom  curve  and  the  shore.  It  is, 
therefore,  not  carried  by  the  littoral  current 
which  is  for  the  most  part  southward,  but  is 
urged  along  the  shore  by  wave  action.  The 
amount  that  has  been  delivered  by  the  streams 
to  the  sea  is  much  greater  than  the  amount  which 
the  sea  has  been  able  to  move  to  the  northward, 
as  shown  by  the  fact  that  nearly  the  entire  shore 
from  Grevtown  to  Port  Limon  has  been  built 
out  into  the  sea  by  this  sand.  The  volume  of 
this  sand  stream  is  then  limited  by  the  trans- 
porting power  of  the  waves  and  not  by  the 
amount  delivered  by  the  streams  to  the  sea. 
The  volume  of  the  sand  stream  must  vary  in 
different  localities  because  portions  of  it  stop  in 
the  indentations  of  the  shore.  Greytown  is  a 
conspicuous  example  of  this.  Northward  from 
Greytown  the  sand  stream  must  diminish  stead- 
ily until  off  Point  of  Rocks  it  ceases  altogether. 


Since  the  building  out  of  the  shore  in  the  vicin- 
ity of  Greytown  is  much  more  rapid  than  it  is 
to  the  northward,  it  is  assumed  that  more  sand 
stops  at  Greytown  than  passes  by.  It  has  been 
previously  stated  that  the  amoimt  which  stops 
at  Greytown  is  known  to  be  about  750,000  cubic 
vards  annuallv.  It  has  therefore  been  assumed 
that  not  more  than  one  million  cubic  yards  pass 
Harbor  Head  annually.  This  latter  assumption 
is  a  conjecture  and  is  not  entitled  to  much 
weight. 

If  these  inferences  are  correct  it  follows  that 
any  pier  or  jetty  built  out  from  the  shore,  at  the 
proposed  harbor  entrance,  must  cross  and  stop 
this  sand  stream  and  that,  to  have  kept  the  sea- 
ward end  of  such  pier  or  jetty  at  the  six-fathom 
curve  for  the  last  ninety  years,  an  annual  exten- 
sion of  at  least  seventy-five  feet  (may  be  much 
more)  would  have  been  necessary.  It  also 
follows  that  the  further  north  the  location,  the 
smaller  will  be  the  volume  of  the  intercepted 
sand  stream. 

Location. 

The  limits  of  the  canal  region  having  been 
found  to  be  narrow  and  the  region  itself  small, 
the  question  of  location  is  very  much  simplified. 
But  narrow  and  small  as  it  is,  there  are  several 
alternative  locations,  each  having  merits  suffi- 
cient to  demand  consideration. 

The  canalization  of  the  San  Juan  river  may 
first  be  considered.  It  has  been  pointed  out 
that  the  floods  in  the  San  Juan  at  the  mouth  of 
the  San  Carlos  may  be  expected  to  exceed 
200,000  cubic  feet  per  second,  while  in  the 
lower  reaches  they  will  exceed  300,000. 

The  San  Carlos  discharges  into  the  San  Juan 
a  large  amount  of  black  sand  which  is  carried 
by  the  latter  river  to  the  sea.  The  channel  of 
the  San  Juan  was  formerly  much  deeper  than 


APPENDIX   I.— REPORT   OP  THE   CHIEF  ENGINEER 


63 


now  and  has  been  filled  to  a  considerable  depth. 
For  example,  at  Upper  Ochoa  the  black  sand  in 
the  bed  of  the  river  was  found  to  be  sixty  feet 
deep;  at  Lower  Ochoa  it  was  seventy  feet  deep; 
at  Tambor  Grande  it  was  one  hundred  and  fifty 
feet  deep.  Below  the  black  sand  was  found  in 
everv  case  the  solid  rock  of  the  old  river  bed. 
This  shows  that  suitable  foundations  for  dams 
can  only  be  found  at  great  depths. 

The  objections  to  canalizing  this  part  of  the 
river  are  its  great  floods,  its  sediment  transporta- 
tions and  the  great  depth  of  suitable  foundations 
for  dams.  These  objections  are  not  wholly  in- 
surmountable, and  if  there  were  no  alternative 
they  might  be  considered.  It  has,  however, 
been  already  pointed  out  that  there  is  an  alterna- 
tive route  going  across  country  from  the  mouth 
of  the  San  Carlos  to  the  sea,  and  that  this  route 
crosses  no  large  streams  or  high  hills  and  pre- 
sents no  unusual  difiiculties.  Since  it  is  unques- 
tionably the  better  of  the  two  plans,  the  canali- 
zation of  the  river  between  the  mouths  of  the 
San  Carlos  and  the  Colorado  will  not  be  further 
considered. 

The  canalization  of  the  lower  San  Juan  from 
the  Colorado  to  Greytown  is  feasible,  because  it 
can  be  cut  off  from  the  main  river  by  a  dam, 
thus  preventing  floods  and  sediment  trans- 
portation. It  will  be  considered  later  in  con- 
nection with  one  of  the  locations. 

The  Canalization  of  the  Upper  San  Juan. 

It  has  already  been  pointed  out  that  this  reach 
of  the  river  has  flood  discharges  of  50,000  cubic 
feet  per  second  where  it  leaves  Lake  Nicaragua, 
and  100,000  above  the  mouth  of  the  San  Carlos, 
that  it  carried  but  little  sediment,  and  that  its 
bottom  between  Machuca  and  Castillo  is  solid 
rock  and  near  the  surface,  which  is  verv  favor- 
able  for  dam  foundations.     Between  Machuca 


and  the  mouth  of  the  San  Carlos  the  solid  rock 
is  about  sixty-five  feet  below  tlie  surface  of  the 
river.  These  conditions  are  much  more  favor- 
able for  canalization  than  those  of  the  lower 
part  of  the  river.  The  flood  discharge  of  50,000 
and  100,000  cubic  feet  per  second  through  fifty 
miles  of  dredged  channel,  with  earth  banks,  is 
the  most  objectionable  feature.  It  is  feared 
that  the  stream  velocities  caused  by  such  floods 
would  be  sufficient  to  seriously  erode  the  channel 
banks,  and  make  na\ngation  difficult.  It  is  be- 
lieved that  a  waste-way  to  the  Pacific  would  suf- 
ficients reduce  the  torrential  floods  so  that  the 
question  of  canalizing  this  part  of  the  river 
would  become  a  fairly  simple  one.  Fortunately 
a  western  waste-way  is  possible  and  at  a  cost  not 
80  great  as  to  be  prohibitive.  This  question  will 
be  more  fully  discussed  under  the  head  of 
"Additional  Waste- Ways.'' 

The  conclusion  reached  may  be  summarized 
as  follows:  The  upper  San  Juan  from  the  lake 
to  the  mouth  of  the  San  Carlos  and  the  lower 
San  Juan  from  the  Colorado  to  Greytown,  can 
be  canalized  at  a  reasonable  cost.  The  re- 
mainder of  the  river  from  the  mouth  of  the 
San  Carlos  to  the  mouth  of  the  Colorado  could 
not  be  canalized  except  at  an  expense  that  would 
be  practically  prohibitive. 

The  location  of  the  canal  from  Lake  Nica- 
ragua to  the  mouth  of  the  San  Carlos  is  shown 
on  Map  Xo.  2.  It  is  practically  the  river  itself. 
It  will  be  observed  that  some  bends  in  the  river 
are  shortened  by  cut-offs  while  others  are  not. 
The  question  whether  or  not  a  shortening  in  the 
route  is  desirable  has  been  determined  by  its 
extra  cost.  The  following  rule  has  governed: 
Wherever  the  length  of  the  canal  could  he  short- 
ened with  an  extra  cost  of  less  than  one-quarter 
of  a  million  dollars  per  mile  of  shortening ,  it  hus 
been  done.     TT7ien  the  extra  cost  exceeded  one- 


64 


NICARAGUA  CANAL  COMMISSION 


quarter  of  a  million  dollars  per  mile  of  short- 
ening it  has  not  been  done. 

This  rule  has  been  derived  as  follows:  It  is 
assumed  that  the  business  through  the  canal  will 
be  ten  million  tons  annually,  that  the  tolls  will  be 
adjusted  so  as  to  produce  the  maximum  revenue, 
and  that  the  rate  of  interest  upon  the  capital 
to  be  invested  in  the  canal  is  four  per  cent,  an- 
nually. The  average  rate  for  carrying  freight 
over  ocean  routes  of  three  thousand  miles  or 
more  is  usually  assumed  by  statisticians  to  be 
one  mill  per  mile-ton.  Of  this  amount  one-half 
is  for  shore  expenses,  loading  and  unloading, 
warehouse,  insurance,  etc.,  leaving  one-half  mill 
per  mile-ton  for  moving  freight  through  the 
water.  It  is  assumed  that  vessels  move  at  half 
speed  in  the  canal.  Then  the  cost  in  the  canal 
would  be  one  mill  per  mileton,  and  the  cost  of 
moving  ten  million  tons  one  mile  would  be  ten 
thousand  dollars.  Therefore,  if  the  canal  could 
be  shortened  one  mile,  ten  thousand  dollars  ad- 
ditional tolls  could  be  collected  annually.  At 
four  per  cent,  this  would  pay  the  interest  on 
one-quarter  of  a  million  dollars.  Therefore, 
under  these  assumptions,  one-quarter  of  a  million 
dollars  could  be  borrowed  and  expended  without 
loss  in  shortening  the  canal  one  mile.  If  the 
shortening  cost  less,  it  would  be  desirable;  if 
more,  it  would  be  undesirable.  The  assumptions 
are  arbitrary.  Therefore,  the  rule  derived  from 
them  has  equal,  but  no  greater,  weight  than  the 
assumptions  themselves. 

From  the  mouth  of  the  San  Carlos  river  to 
the  sea  several  routes  and  variants  have  been 
considered.  They  are  all  shown  on  Map  No.  2. 
They  include  all  of  the  characteristic  feasible 
routes.  An  infinite  number  of  minor  changes 
in  location  are  possible,  some  of  them  probably 
profitable  to  some  small  extent  But  it  is  be- 
lieved that  there  is  no  route  worthy  of  considera- 


tion that  is  not  substantially  included  within  the 
limits  of  those  here  given. 

The  locations  on  the  west  side  are  shown 
on  Map  Xo.  2.  They  include  former  loca- 
tions made  by  the  Maritime  Canal  Company. 
The  Commission's  location  is  made  with  ref- 
erence to  minimum  excavation,  suitable  lock 
sites  and  a  waste-way  to  the  Pacific.  The 
valleys  are  so  narrow  and  the  physical  condi- 
tions so  sharply  defined  that  no  considerable 
variation  in  location  is  possible.  It  is  believed 
that  the  route  chosen  cannot  be  much,  if  any, 
improved. 

Fluctuations  in  Lake  Level. 

It  has  already  been  mentioned  that  Lake 
Nicaragua  has  a  range  in  elevation  of  at  least 
ten  feet,  and  there  are  traditions  of  still  greater 
changes. 

If  used  for  a  canal  it  is  desirable  to  limit  these 
fluctuations  as  much  as  possible.  A  very  fair 
determination  of  what  can  be  safely  done  in  this 
direction,  can  be  derived  from  the  data  now  in 
hand.  These  data  consist,  first,  of  the  observa- 
tions made  by  the  Commission  during  the  year 
1898.  There  were  observed,  the  rainfall  in  the 
entire  basin  of  Lakes  Nicaragua  and  Managua; 
the  continuous  outflow  from  Lake  Nicaragua; 
the  evaporation  from  its  surface,  and  the  daily 
changes  in  its  elevation.  These  obsei*vations  are 
trustworthy  and  ample  for  the  year.  In  addi- 
tion there  is  available  a  rainfall  record  made  at 
Rivas,  continuous  for  nearly  twenty  years.  Mr. 
Davis  shows  that  this  record  appears  to  be  trust- 
worthy. Since  the  fluctuations  in  the  lake  sur- 
face are  a  direct  and  almost  linear  fluctuation  of 
the  rainfall,  it  is  possible  to  determine  what  this 
relation  is  from  the  observations  of  1898,  when 
both  rainfall  and  fluctuations  were  observed, 
and  then  apply  it  directly  to  the  preceding  years 


APPENDIX  I.— REPORT   OF  THE   CHIEF   ENGINEER 


65 


when  only  rainfall  was  observed.  In  this  way 
the  fluctuations  at  any  time  during  the  last 
twenty  years,  can  be  determined  with  reasonable 
accuracy.  The  investigation  has  been  made  as 
follows:  Th3  observed  evaporation  from  the 
lake  surface  in  1898  was  fiftv-two  inches.  This 
result  is  the  mean  of  three  stations  around  the 
lake.  The  monthly  rate  ranged  from  6.5  inches 
in  April  to  3.1  inches  in  September;  April  be- 
ing a  dry  month  and  September  a  wet  month. 
1898  was  an  imusually  wet  year.  It  has  been 
assumed  by  Mr.  Davis  that  in  a  dry  year  the 
evaporation  from  the  lake  surface  would  be  as 
much  as  sixty  inches.  Only  one  other  assump- 
tion has  been  found  necessary  to  complete  the 
discussion.  In  determining  the  relation  be- 
tween rainfall  at  Rivas  and  rise  in  the  lake  sur- 
face the  following  method  was  used.  It  was 
found  that  for  the  year  1898  one  hundred  and 
eight  inches  (108)  of  rainfall  at  Rivas  corre- 
sponded to  a  rise  in  the  lake  of  one  hundred  and 
fifty-four  (154)  inches.  This  is  the  only  di- 
rectly observed  relation  that  we  have.  It  is  not 
believed  that  exactlv  the  same  ratio  will  hold 
for  the  different  rates  of  rainfall.  Mr.  Davis 
says  in  Appendix  III: 

"  While  we  have  no  conclusive  data  upon 
which  to  estimate  the  percentage  of  nm-off  to 
rainfall  in  the  basin  of  Lake  Nicaragua,  it  is  well 
established,  as  a  general  rule,  that  in  any  given 
basin  the  greater  the  rainfall  in  a  given  time  the 
greater  the  percentage  of  nm-oif.  So  that  if 
the  rainfall  were  increased  twenty-one  per  cent, 
the  nm-off  should  be  increased  somewhat  more. 
Say  twenty-five  per  cent." 

If  this  assumption  be  applied  to  the  preceding 
observations,  the  following  table  is  obtained 
showing  the  rise  in  Lake  Nicaragua,  cor- 
responding   to    different    rates    of    rainfall    at 

Rivas. 

5 


30  in.  of  rainfall  at  Rivas  corresponds  to  34 
in.  rise  in  lake. 

40  in.  of  rainfall  at  Rivas  corresponds  to  48 
in.  rise  in  lake. 

50  in.  of  rainfall  at  Rivas  corresponds  to  63 
in.  rise  in  lake. 

60  in.  of  rainfall  at  Rivas  corresponds  to  78 
in.  rise  in  lake. 

70  in.  of  rainfall  at  Rivas  corresponds  to  93 
in.  rise  in  lake. 

80  in.  of  rainfall  at  Rivas  corresponds  to  109 
in.  rise  in  lake. 

90  in.  of  rainfall  at  Rivas  corresponds  to  125 
in.  rise  in  lake. 

100  in.  of  rainfall  at  Rivas  corresponds  to  141 
in.  rise  in  lake. 

110  in.  of  rainfall  at  Rivas  corresponds  to  157 
in.  rise  in  lake. 

120  in.  of  rainfall  at  Rivas  corresponds  to  175 
in.  rise  in  lake. 

130  in.  of  rainfall  at  Rivas  corresponds  to  192 
in.  rise  in  lake. 

This  table  is  intended  to  be  used  onlv  in  com- 
paring  the  total  rainfall  of  different  years. 
When  partial  seasons  are  discussed  a  special  de- 
termination is  made  for  each  case. 

As  a  preliminarv  step  in  the  investigation,  the 
amount  of  water  nccessarv  for  the  use  of  a  canal 
has  been  determined  as  follows:  If  the  busi- 
ness of  the  canal  should  be  10,000,000  tons  an- 
nually and  2000  tons  should  be  passed  at  each 
lockage,  then  5000  lockages  would  be  required 
on  each  side.  If  the  vessels  were  all  going  one 
wav  5000  lockfuls  of  water  would  l)e  used, 
which  would  be  the  maximum.  If  going  alter- 
nately in  opposite  directions,  then  2500  lock- 
fuls would  be  used,  which  would  bo  a  mininiuni. 
If  the  mean  be  taken  then  3750  lockfuls  would 
be  used  annually  on  each  side,  or  7500  on  both 
sides.  With  a  six-lock  svstem  this  would  amount 
to  7,341,600,000  cubic  feet  annually. 

leakage  is  a  more  variable  quantity,  depend- 


66 


NICARAGUA  CANAL  COMMISSION 


ing  upon  the  condition  of  the  gates,  valves,  em- 
bankments, etc.  It  is  estimated  that  the  leak- 
age in  the  Poe  Lock  at  Sault  Ste.  Marie  averages 
200  cubic  feet  per  second.  If  this  be  taken 
for  the  leakage  of  one  lock  out  of  Lake  Nica- 
ragua then  the  total  leakage  of  the  two  sides 
would  be  12,014,400,000  cubic  feet  annually. 

For  the  purposes  of  operating  the  machinery 
of  the  locks,  generating  lights,  etc.,  it  is  assumed 
that  sixty  horse-power  operating  half  the  time 
.will  be  sufficient  for  one  lock.  With  a  fall  of 
18.4  feet  and  a  loss  of  twenty-five  per  cent,  in 
installation,  this  will  require  1,135,290,000 
cubic  feet  annually.  The  sum  of  these  three 
quantities  is  sufficient  to  low^er  the  lake  level 
three  inches  annually.  The  probable  changes 
in  the  lake  level  during  the  period  of  least  rain- 
fall \vill  first  be  determined. 

From  November  1,  1889,  to  June  1,  1891,  a 
period  of  nineteen  months,  the  total  rainfall  at 
Rivas  was  38.39  inches.  This,  from  the  pre- 
ceding table  would  have  raised  the  lake  45.75 
inches.  Evaporation  would  have  lowered  it 
ninety-five  inches  and  the  needs  of  the  canal 
w^ould  have  lowered  it  4.75  inches.  Therefore, 
the  lake  at  the  end  of  this  period  would  have 
been  54  inches  lower  than  at  the  beginning, 
even  though  there  had  been  no  outflow.  This 
is  the  driest  period  observed,  but  it  is  not  at  all 
anomalous.  From  the  beginning  of  December, 
1884,  to  the  end  of  April,  1886,  a  period  of  sev- 
enteen months,  the  total  rainfall  was  37.43 
inches,  which  w^ould  raise  the  lake  surface  44.40 
inches,  while  evaporation  and  the  needs  of  a 
canal  would  lower  it  89  inches,  thus  leaving 
it  44.6  inches  lower  at  the  end  of  the  period 
than  at  the  beginning.  Again,  from  the  begin- 
ning of  November,  1894,  to  the  end  of  April, 
1896,  a  period  of  19  months,  the  total  rainfall 
was  45.15  inches  which  would  cause  the  lake  to 


rise  55.72  inches,  w^hile  evaporation  would  have 
lowered  it  95  inches  and  the  needs  of  a  canal 
w^ould  have  lowered  it  4.75  inches  more,  thus 
leaving  the  lake  44  inches  low^r  at  the  end  of 
the  dry  period  than  at  the  beginning.  The  re- 
currence of  such  dry  periods  three  times  in 
twenty  years  show-s  that  they  are  to  be  expected 
in  the  future  and  should  be  provided  for.  The 
only  way  in  which  such  provision  can  be  made,  is 
by  the  temporary  storage  of  water  in  the  lake. 
If  at  the  beginning  of  the  dry  period  the  lake 
had  been  54  inches  higher  than  necessary  for  a 
30-foot  draft,  then  at  the  end  of  the  dry  period 
the  draft  would  have  been  reduced  to  exactlv 
30  feet.  A  fluctuation  of  54  inches  is,  there- 
fore, absolutely  necessary  to  provide  for  periods 
of  as  small  rainfall  as  have  occurred  in  the  last 
20  years.  Since  it  would  be  impossible  to  con- 
trol the  lake  within  exact  limits  an  additional 
18  inches  of  fluctuation  has  been  arbitrarily 
added,  making  the  total  allowable  fluctuation 
six  feet.  This  fluctuation  is  necessarj^  in  order 
to  maintain  a  30-foot  draft  during  dry  periods. 

The  periods  of  large  rainfalls  will  next  be  con- 
sidered. 

Between  June  18  and  October  29,  1898,  a 
period  of  132  days,  the  rainfall  at  Rivas  was 
76.36  inches,  the  lake  rose  48.00  inches;  the  out- 
flow lowered  it  32.76  inches  and  the  evaporation 
on  the  lake  surface  lowered  it  16.88  inches. 
Therefore,  if  there  had  been  no  evaporation  on 
the  lake  or  outflow  from  it,  it  would  have  risen 
97.64  inches. 

Between  May  17  and  October  27,  1897,  a 
period  of  164  days,  the  rainfall  at  Rivas  was 
112.42  inches.  This  was  the  period  of  greatest 
rainfall  shown  in  the  Rivas  records  since  1879. 
The  amount  of  fluctuation  in  the  surface  of  Lake 
Nicaragua  caused  by  this  rainfall  was  not  ob- 
served; an  attempt  will  be  made  to  determine 


APPENDIX   I.— REPORT   OF  THE   CHIEF  ENGINEER 


67 


it  by  comparison  with  the  wet  portion  of  1898, 
when  both  fluctuation  and  rainfall  were  care- 
fully measured.  The  problem  may  then  be 
briefly  stated  as  follows:  If  a  rainfall  of  76.36 
inches  in  132  days  would  cause  a  rise  in  the  lake 
surface  of  97.64  inches,  what  rise  would  be 
caused  by  a  rainfall  of  112.42  inches  in  164 
days?  The  ratio  between  rainfall  and  change 
in  lake  level,  as  given  in  the  preceding  table, 
cannot  be  used  for  this  problem,  because  in  this 
case  only  portions  of  a  season  are  considered. 
At  the  beginning  of  these  periods  the  streams 
and  marshes  were  drained,  and  empty.  At  the 
end  they  were  overflowing  and  the  entire  run-off 
due  to  the  rainfall  had  not  yet  occurred.  There- 
fore, this  problem  must  be  solved  as  a  special 
case.  If  the  rise  was  exactly  proportional  to 
the  rainfall  it  would  be  143.7  inches,  provided 
ithere  was  no  evaporation  on  the  lake  nor  out- 
flow from  it.  It  is,  however,  probable  that  in 
this  case  as  in  the  preceding  one,  the  greater 
dailv  rate  of  rainfall  in  1897  would  cause  the 
lake  to  rise  slightly  more  than  the  proportional 
amount.  An  examination  shows  that  the  daily 
rate  of  rainfall  in  1897  was  18  per  cent,  greater 
than  in  1898.     Using  the  ratio  as  before,  the 


The  question  as  to  what  amoimt  of  fluctuation 
in  the  lake  will  be  necessary  to  take  care  of  this 
rainfall  will  next  be  considered.  The  estimated 
rise  of  148.58  inches  must  be  provided  for  by 
evaporation,  outflow  and  temporary  storage  in 
the  lake. 

Assuming  the  ratio  of  evaporation  from  the 
lake  surface  to  be  the  same  as  in  1898,  it  would, 
for  the  164  davs,  amoimt  to  20.97  inches.  Sub- 
tracting  this  from  148.58  inches  leaves  127.61 
that  must  be  provided  for  by  outflow  and  tem- 
porary storage. 

The  lake  has  an  area  of  3000  square  miles,  a 
rise  in  its  surface  of  127.61  inches  would  be 
equivalent  to  889,408,618,000  cubic  feet.  If 
this  should  run  out  of  the  lake  in  164  days,  the 
mean  discharge  would  be  62,769  cubic  feet  per 
second  and  there  would  be  no  permanent  change 
in  the  elevation  of  the  lake  surface.  If  the  lake 
should  be  permitted  to  rise  one  foot,,  then  the 
mean  discharge  would  be  reduced  to  56,866  and 
each  additional  foot  that  the  lake  is  allowed  to 
rise  will  reduce  the  mean  rate  of  discharge  by 
an  equal  amount.  The  following  table  shows 
the  required  rate  of  discharge  for  each  foot  of 
fluctuation : 


!N'o  fluctuation  requires  62,800  cubic  feet  of  discharge. 


1  foot 

56,900 

2  feet 

51,000 

3     " 

45,100 

4     " 

39,200 

5     " 

33,300 

rise  in  the  lake  would  be  22  per  cent,  greater. 
Applying  this  per  cent,  the  computed  rise  in 
the  lake  for  1897  would  be  increased  from  143.7 
inches  to  148.58  inches.  This,  then,  is  the  esti- 
mated amount  of  fluctuation  that  would  have 
occurred  during  the  period  of  greatest  rainfall 
of  the  last  20  years,  if  there  had  been  no  evap- 
oration on  the  lake  nor  outflow  from  it. 


It  appears  from  this  table  that  if  a  waste-way 
having  a  capacity  of  33,300  cubic  feet  per  sec- 
ond be  provided,  the  fluctuation  in  the  lake  could 
be  limited  to  five  feet  for  a  rainfall  as  great  as 
any  that  has  occurred  in  the  last  twenty  years. 

Since  the  canal  itself  will  incidentally  provide 
waste-ways,  exceeding  this  in  capacity,  it  ap- 
pears that  not  more  than  five  feet  of  rise  need 


68 


NICARAGUA  CANAL  COMMISSION 


be  caused  by  the  largest  rainfall.  Therefore, 
the  range  of  fluctuation  of  6  feet  found  suf- 
ficient for  dry  periods  will  also  suffice  for  wet 
seasons. 

This  determination  of  the  volume  of  the  larg- 
est flood  in  the  last  twenty  years  is  believed  to 
be  reasonably  correct.  It  is  confirmed  by  a  dis- 
cussion of  the  flood-plains  of  the  San  Juan  river. 
This  discussion  made  by  Dr.  Hayes,  shows  that 
floods  as  great  as  the  one  under  consideration 
probably  occur  as  frequently  as  once  in  twenty 
years,  while  still  greater  floods  occur  at  much 
longer  intervals.  It  is  believed,  however,  that 
it  will  be  sufficient  to  control  floods  equal  to 
the  largest  that  have  occurred  in  the  last  twenty 
years,  simply  providing  locks,  embankments, 
etc.,  with  sufficient  heights  so  that  when  higher 
floods  occur  no  damage  will  be  done  to  the  canal. 

It  will  be  observed  that  the  preceding  deter- 
mination of  the  probable  changes  in  lake  level 
are  based  upon  the  assumption  that  the  average 
rainfall  in  the  basin  of  Lake  Nicaragua  varies 
as  the  rainfall  at  Rivas.  In  general,  the  aver- 
age rainfall  in  any  considerable  area  does  not 
have  as  wide  a  range  as  the  rainfall  at  a  single 
station  within  the  area.  Therefore,  the  pre- 
ceding determination  of  the  fluctuation  in  the 
level  of  Lake  Nicaragua  is  more  likely  to  be  too 
large  than  too  small. 

Grade. 

Under  your  instructions  the  grade  has  been 
designed  so  as  to  give  a  minimum  depth  of  30 
feet  in  the  canal  at  all  stages  of  the  sea,  lake  and 
ocean.  For  this  purpose  tide  gages  w-ere  ob- 
served at  Greytown  and  Brito  for  several 
months.  The  grade  at  the  bottom  of  the  canal 
at  these  points  was  placed  at  30  feet  below  mean 
low  tide.  At  Greytown  mean  low  tide  is  about 
one-half  foot  below  mean  sea  level;  at  Brito  it 


is  about  four  and  one-half  feet.  The  precise 
levels  show  that  the  Pacific  ocean,  during  the 
time  our  observations  were  made,  was  about  one 
foot  lower  than  the  Caribbean  sea,  therefore, 
the  grade  at  Brito  is  about  five  feet  lower  than 
at  Greytown,  and  consequently  the  maximum 
lift  on  the  west  side  will  be  five  feet  more  than 
on  the  east  side,  while  the  minimum  will  be  three 
feet  less.  The  upper  level  of  the  canal  extends 
from  near  Buen  Eetiro  on  the  west  side,  to  near 
Machuca  on  the  east  side. 

The  upper  limit  to  which  the  lake  will  be  al- 
lowed to  rise  has  been  fixed  by  you  at  110  feet 
above  the  mean  level  of  the  Caribbean  sea. 
The  permissible  fluctuation  has  been  limited  to 
six  feet.  Therefore,  the  lower  limit  of  the  lake 
surface  is  104  feet  above  sea  level  and  the  grade 
of  the  upper  level  of  the  canal  is  74  feet  above 
sea  level.  The  grade  of  the  intermediate  parts 
of  the  canal  is  determined  bv  the  lifts  of  the 

ft- 

locks. 

Additional  W^vste-Ways. 

It  is  proposed  to  control  the  lake  level  be- 
tween an  elevation  of  104  feet  and  110  feet 
above  sea  level  by  means  of  dams  in  the  San 
Juan  river.  These  dams  are  to  be  provided  with 
valves  and  the  outflow  from  the  lake  will  be 
entirely  cut  off  for  a  considerable  part  of  each 
season.  It  is  also  proposed  to  place  the  material 
which  is  excavated  from  the  river  in  piles  along 
both  banks  of  the  river. 

There  will  be  four  things  that  will  tend  to 
make  the  floods  in  the  riv^r  higher  than  hereto- 
fore. First,  the  dams  in  the  river  will  some- 
what obstruct  the  flow  by  diminishing  the  slope 
and  velocity.  Second,  the  spoil  banks  will  con- 
tract the  section  and  prevent  the  flood  waters 
from  so  readily  escaping  into  the  adjacent 
marshes.  Third,  the  water  will  be  retained  in 
the  lake  by  the  dams  so  that  at  the  beginning  of 


APPENDIX   I.— REPORT   OF  THE   CHIEF  ENGINEER 


69 


the  rainy  season  the  river  will  be  at  a  much 
higher  stage  than  formerly.  Fourth,  the  en- 
tire outflow  from  the  lake  will  be  precipitated 
into  the  river  in  five  or  six  months  instead  of  the 
entire  year  as  formerly.  On  the  other  hand, 
the  increased  cross  section  of  the  river  caused 
by  the  excavation  will  tend  to  facilitate  the  out- 
flow. This  is  a  large  factor  and  it  appears  (so 
far  as  computations  can  show)  sufficient  to  about 
offset  the  preceding  four  so  that  the  water  might 
all  be  carried  through  the  San  Juan  river,  with 
no  greater  velocity  or  higher  floods  than  for- 
merly. 

The  computed  effect  of  all  these  hypothetical 
cases  is  uncertain,  and  it  is  possible  that  the 
completed  canal  might  have  greater  floods  and 
velocities  than  the  San  Juan  river  now  has. 
Again  it  is  desirable  that  the  current  in  a  canal 
shall  be  as  small  as  possible.  Still  water  is  the 
ideal  case.  If  the  upper  San  Juan  is  canalized 
its  channel  banks  will  be  of  sloping  earth,  sub- 
merged, and  invisible.  Its  curves  have  a  pro- 
posed minimum  radius  of  3000  feet.  It  is  evi- 
dent that  strong  currents  will  make  navigation 
difficult  and  will  tend  to  erode  the  banks  and 
refill  the  excavated  channel.  In  order  to  re- 
duce these  objections  to  a  minimum,  a  waste-way 
on  the  west  side  is  proposed. 

The  conditions  are  as  follows:  The  estimated 
maximum  outflow  from  Lake  Nicaragua  is  50,- 
000  cubic  feet  per  second.  The  drainage  of 
the  valley  of  the  upper  San  Juan  sometimes 
amounts  to  50,000  cubic  feet  per  second,  so  that 
the  estimated  maximum  discharge  of  the  San 
Juan  above  the  San  Carlos  is  100,000  cubic 
feet  per  second.  In  order  to  obtain  a  minimum 
current  in  the  canalized  portion  of  the  river,  it 
is  proposed  to  divert  all  the  drainage  of  Lake 
Nicaragua  westward  to  the  Pacific.  The  drain- 
age of  the  San  Juan  valley  will  be  taken  down 


the  river,  though  at  times  of  great  floods  it  will 
be  divided  into  two  parts  by  the  dam  at  Ma- 
chuca,  one-half  being  temporarily  turned  back 
into  the  lake.  In  this  way  the  maximum  dis- 
charge in  the  river  will  be  reduced  to  25,000 
cubic  feet  per  second,  and  the  maximum  velocity 
to  1.5  feet  per  second. 

It  is  proposed  to  make  the  waste-way  on  the 
west  side  through  the  canal  for  the  first  ten 
miles  from  the  lake.  The  water  will  then  pass 
out  of  the  canal  through  controlling  works,  sim- 
ilar to  those  in  the  Chicago  drainage  canal. 
After  being  discharged  from  the  canal  the  water 
will  pass  down  to  the  sea  through  the  channel 
of  the  Eio  Grande,  which  will  be  enlarged  and 
rectified  in  places. 

The  ten  miles  of  canal  that  it  is  proposed  to 
use  for  a  waste-way  will  be  almost  entirely 
through  rock  cutting.  The  sides  of  the  canal 
will  be  almost  vertical  and  may  be  protected  by 
timber  fenders.  The  water  from  the  lake  car- 
ries practically  no  sediment.  A  velocity  of  five 
feet  per  second  will  neither  injure  the  canal 
nor  materially  interfere  with  navigation.  It  is 
proposed  to  make  this  ten  miles  of  the  canal 
200  feet  wide  with  a  fall  of  two  feet.  This 
with  a  velocity  of  not  more  than  five  feet  per 
second  will  give  a  mean  discharge  of  33,000 
cubic  feet  per  second  which,  as  already  shown, 
will  be  sufficient  to  limit  the  fluctuations  of  the 
lake  surface  within  five  feet.  The  widening  of 
this  part  of  the  canal  to  200  feet  will  be  a  sub- 
stantial benefit  to  navigation.  If  greater  floods 
should  occur,  there  are  additional  resources  in 
reserve.  The  discharge  through  the  waste-ways 
both  on  the  east  and  west  sides  could,  with  some 
inconvenience  to  navigation,  be  temporarily  in- 
creased and  finally,  if  the  lake  should  rise  a  little 
higher  than  110  feet  above  sea  level,  but  little 
harm  would  be  done. 


70 


NICARAGUA  CANAL  COMMISSION 


Estimates. 

Estimates  of  amounts  of  material  and  com- 
parative cost  of  construction  have  been  made 
for  all  the  routes  indicated  on  the  map.  The 
following  nomenclature  has  been  directed  by 
vou.  The  several  routes  on  the  west  side  are 
called  variants  of  the  Childs  route. 

The  Maritime  Canal  Company's  route  from 
the  lake  to  Greytown,  leaving  the  river  at  Ochoa 
and  crossing  the  Eastern  Divide  is  called  the 
Menocal  route.     It  has  one  variant. 

The  route  from  the  lake  to  the  mouth  of  the 
San  Carlos  and  then  across  the  coimtry  by  way 
of  Lake  Silico  is  called  the  Lull  route.  There 
are  four  variants  to  this  route.  The  one  north 
of  Lake  Silico  is  called  Variant  I.  The  one 
through  Lake  Silico  is  called  Variant  II.  The 
one  south  of  Lake  Silico  is  called  Variant  III, 
and  the  one  passing  through  the  Agua  Dulce 
lagoon  is  called  Variant  IV. 

A  number  of  different  forms  of  construction 
have  been  considered.  On  the  east  side  esti- 
mates have  been  made  for  different  lock  systems. 
Systems  of  3,  5,  6,  7  and  8  locks  with  1,  2  and  3 
dams  in  the  river  have  been  considered.  On 
the  west  side  systems  of  3,  4,  5  and  6  locks  have 
been  considered. 

Unit  prices  have  been  derived  as  follows: 

The  cost  of  excavating  has  been  obtained  by 
comparison  with  the  Chicago  Drainage  Canal. 
Here  the  actual  average  cost  was:  for  cubic  yard 
of  rock,  75  cents;  for  cubic  yard  of  earth,  28 
cents,  ilessrs.  L.  E.  Cooley  and  Isham  Ran- 
dolph have  expressed  their  opinions  that  if  the 
work  should  be  repeated,  it  could  be  done  for  65 
cents  and  25  cents,  respectively.  These  prices 
are,  therefore,  used  as  a  basis  of  comparison. 

If  the  Nicaragua  Canal  were  located  near 
Chicago  and  its  rock  and  earth  excavation  simi- 
lar in  character  to  that  of  the  Drainage  Canal, 


then  its  rock  and  earth  could  be  excavated  for 
65  cents  and  25  cents  per  cubic  yard.  Com- 
paring the  material  in  the  two  localities:  The 
earth  in  the  Nicaragua  Canal  varies  in  character 
from  soft  rock  to  diluted  silt.  In  the  Chicago 
Canal,  the  range  is  equally  as  wide.  It  is  be- 
lieved that  the  general  average  in  the  two  lo- 
calities w^ould  prove  to  be  substantially  the  same. 
Therefore,  it  is  assumed  that,  if  the  Nicaragua 
Canal  were  located  near  Chicago,  the  average 
cost  of  its  earth  excavation  would  be  25  cents 
I>er  cubic  yard. 

The  rock  between  Lake  Nicaragua  and  the 
Pacific  is  shale  and  sandstone,  thinlv  stratified 
and  much  broken.  Some  pits  of  considerable 
depth  have  been  excavated  without  blasting;  the 
rock  has  been  used  for  macadamizing  the  roads. 
It  is  believed  that  a  large  part  of  this  rock  could 
be  excavated  with  steam  shovel  without  blast- 
ing. It  is  drilled  slightly  more  easily  than  the 
Chicago  limestone,  and  is  much  more  brittle. 
The  location  of  the  spoil  banks  is  not  quite  so 
favorable  as  in  the  Chicago  works.  These  two 
opposite  conditions  have  been  taken  as  equal,  it 
has,  therefore,  been  assumed  that  it  could  be 
handled  for  the  same  price  as  the  Chicago  rock. 
Between  Lake  Nicaragua  and  the  Caribbean  sea 
the  rock  is  basalt,  dacite  and  sandstone.  The 
sandstone  is  in  such  small  quantities  that  it  need 
not  be  considered.  The  basalt  and  dacite  are 
both  considerablv  harder  to  drill  and  blast  than 
the  Chicago  limestone  but  somewhat  easier  than 
granite.  Again  in  the  larger  cuts  the  waste  ma- 
terial will  have  to  be  transported  horizontally 
three  or  four  miles  to  the  dumping  ground.  For 
these  reasons  it  is  estimated  that  the  cost  per 
yard  will  be  increased  10  cents.  Therefore,  it 
is  assumed  that  if  the  Nicaragua  Canal  were  lo- 
cated near  Chicago,  the  cost  of  excavating  this 
rock  would  be  75  cents  {x?r  cubic  yard  on  the 


APPENDIX   I.— REPORT   OF  THE   CHIEF  ENGINEER 


71 


east  side  and  65  cents  per  cubic  yard  on  the 
west  side.  So  far  the  data  has  been  reasonably 
full  and  exact  and  the  conclusions  cannot  be 
much  in  error. 

It  yet  remains  to  assign  the  relative  cost  of 
work  in  the  United  States  and  in  Central  Ameri- 
ca. This  will  involve  greater  uncertainty,  for 
the  reason,  that  there  have  been  no  large  works 
in  Central  America  with  which  comparison  can 
be  made,  except  the  Panama  Canal,  and  for 
many  reasons  it  is  believed  that  comparison  with 
this  work  would  be  misleading.  There  has, 
however,  been  some  railroad  building  in  all  of 
tlie  Central  American  States,  often  in  amounts 
sufficiently  large  so  that  the  entire  labor  was 
brought  to  the  country  from  the  outside,  thus 
making  the  conditions  of  labor  somewhat  similar 
to  those  which  would  obtain  if  the  Nicaragua 
Canal  should  be  built.  An  analysis  of  the  cost 
of  several  of  these  roads  has  been  obtained  from 
engineers  who  built  them.  In  one  case  a  small 
amount  of  work  under  very  unfavorable  circum- 
stances cost  about  100  per  cent,  more  than  it 
would  in  the  United  States.  In  other  cases  the 
difference  was  less  than  50  per  cent  The  range 
in  results  was  quite  wide  but  all  fell  between 
25  and  100  per  cent  in  excess  of  similar  work 
in  the  United  States. 

From  a  consideration  of  all  the  data  available 
the  following  ratios  have  been  assigned: 

The  rock  on  both  sides  and  the  earth  on  the 
west  side  will  cost  50  per  cent,  more  to  exca- 
vate in  Nicaragua  than  in  the  United  States. 

In  view  of  the  excessive  rainfall,  the  earth  on 
the  oast  side  would  cost  75  per  cent,  more  in 
!Xiearagua  than  in  the  United  States.  Apply- 
ing these  ratios  to  the  prices  previously  obtained, 
the  unit  cost  of  excavation  is  found  to  be  as  fol- 
low? : 


Rock  on  the  east  side $1.12  per  cubic  yd. 

Rock  on  the  west  side 07    "       "      ** 

Earth  on  the  east  side 44    '•'       "      " 

Earth  on  the  west  side 37    "       "      " 

The  cost  of  the  locks  has  been  obtained  by 
comparison  with  those  at  Sault  Ste.  Marie.  The 
material  estimated  for  is  concrete  walls,  steel 
gates,  wooden  floors  and  conduits.  The  strength 
and  dimensions  of  the  parts  necessary  for  the  re- 
quired Nicaragua  locks,  were  first  determined 
by  comparison  with  the  locks  at  Sault  Ste.  Marie. 
The  imit  prices  that  have  actually  been  paid  at 
the  Sault  were  then  applied.  Up  to  this  point 
the  data  are  quite  full  and  the  result  is  believed 
to  be  reasonably  exact.  The  excess  of  cost  in 
Nicaragua  over  that  in  the  United  States  is  more 
uncertain.  It  is  assumed  to  be  33  per  cent.  It 
has  been  taken  lower  than  that  for  excavation 
because  a  large  part  of  lock  construction  is  for 
material,  some  of  which  can  be  furnished  in 
Nicaragua  at  only  a  slight  advance  over  the 
price  in  the  United  States.  These  added  per- 
centages of  75,  50  and  33  are  believed  to  be 
large  enough  to  cover  all  contingencies.  There- 
fore, in  the  following  estimates  these  unit  prices 
have  been  reduced  so  that  an  item  of  20  per 
cent,  for  contingencies  can  be  added  to  the  total. 
The  two  items  of  excavation  and  lock  building 
amount  to  about  80  per  cent,  of  the  total  cost 
These  unit  prices  are,  therefore,  relatively  very 
important.  The  remaining  imit  prices  are  de- 
termined from  such  information  as  could  be  ob- 
tained in  Nicaragua  and  the  United  States. 
Some  of  the  items  are  ver^'  uncertain,  but  it  is 
believed  that  the  aggregate  will  prove  to  be 
reasonablv  correct. 

The  following  are  the  imit  prices  used  in  all 
the  estimates: 


72 


NICARAGUA  CANAL  COMMISSION 


Prices  for  the  East  Side. 

Earth  excavation $     .37  per  cu.  yd. 

(Obtained  by  adding  60^  to 
Chicago  price  of  25^  per 
cii.  yd.) 

Rock  excavation 93    ''    ''     " 

(Obtained  by  adding  10^  to 
Chicago  price  of  65ff  and 
then  adding  24ji^  to  the 
sura.) 

Rock  in  Greytown  breakwater.    1.75    "    ^*     " 

Timber  cribs 3.25    ''    "     " 

Clay  puddle  and  back-filling, 
exclusive  of  cost  of  excava- 
tion     50    "    "     " 

Concrete  in  structures,   other 

than  locks    8.30    "    ''     " 

Concrete  in  locks 7.23    "    *"•     " 

Stone  pitching,  on  embank- 
ments        2.00    "    sq.  yd. 

Timber  in  structures 60.00    "  M.B.M. 

Clearing 75.00    "  acre. 

Clearing  and  gnibbing 100.00    "      " 

Prices  for  West  Side. 

Earth  excavation $     .31  per  cu.  yd. 

(Obtained  by  adding  24:^  to 

Chicago   price   of   25^   per 

cu.  yd.) 
Rock  excavation 81    "    **     " 

(Obtained  by  adding  24j^  to 

Chicago   price   of   65^   per 

cu.  yd.) 
Rock  in  Brito  breakwater  .  .  .      1.50    ''    "     " 

Timber  cribs 3.00    ''    ''     " 

Clay  puddle  and  back-filling, 

exclusive  of  cost  of  excava- 
tion     50    "    *^     " 

Concrete  in  structures,   other 

than  locks    8.30    "    "     " 

Concrete  in  locks 7.23    "    "     '' 

Stone  pitching 1.75    "    sq.  yd. 

Timber  in  structures 60.00    "  M.B.'m. 

Clearing 75.00    "  acre. 

Clearing  and  grubbing 100.00    "      " 


The  first  estimate  is  for  the  Maritime  Canal 
Company's  proposed  canal. 

The  location  is  shown  by  the  dotted  lines  on 
Map  No.  2,  and  is  exactly  the  location  chosen 
by  the  Canal  Company.  The  dimensions  are 
those  assigned  by  the  Company.  The  more  im- 
portant ones  are  as  follows: 

Width  of  canal,  in  earth  80  to  120,  in  rock 
100,  in  river  125,  in  lake  125  to  275.  Depth 
28  to  30. 

The  number  of  locks  is  6.  The  3  on  the  east 
side  have  lifts  of  31,  35  and  40  feet;  and  the  3 
on  the  west  have  lifts  of  42.5,  42.5  and  30  feet; 
usable  length  C50  feet;  width  80  feet 

The  slopes  in  rock  range  between  one  hori- 
zontal to  one  vertical  and  one  horizontal  to  five 
vertical;  in  earth  between  six  horizontal  to  one 
vertical  and  three  horizontal  to  one  vertical. 

The  total  length  of  the  canal  from  the  7-fath- 
om  curve  in  the  Caribbean  sea  to  the  7-fathom 
curve  in  the  Pacific  ocean  is  186.56  miles. 

Minimum  elevation  of  lake  surface  110  feet 
above  mean  sea  level  (Caribbean  sea  level). 

The  estimate  of  cost  is  made  up  as  follows: 

Estimate  ox  Menocal  Route  and  Pl^vns. 

Eastern  Division. 

Excavation  earth,  cu.  yds.  45,731,- 

712,  at  37ff $16,920,733 

Excavation  rock,  cu.  yds.  9,278,803, 

at  93^ 8,629,287 

Embankment,  Deseado  basin 1,304,919 

Embankment,  San  Carlos  ridge. . .  261,114 

Embankment,  San  Francisco  ridge.  4,780,960 

Ochoa  dam 1,875,071 

Three  locks 5,154,760 

San  Francisco  and  Deseado  sluices.  1,947,484 

San  Carios  sluices 879,408 

Clearing  and  grubbing,  acres  731.5, 

at  $100 73,150 

Clearing,  acres  1186,  at  $75 88,950 

Greytown  breakwater,  etc 1,273,295 


APPENDIX   I.— REPORT   OF  THE  CHIEF  ENGINEER 


73 


Stone   pitching,   sq.    yds.    7680,    at 

$1.67    $12,820 

Guard  gate 171,708 

Railway,  Greytown  to  Ochoa 1,604,200 

Telegraph,  miles  72,  $500 36,000 

$45,013,865 

Western  Division. 

Childs  Route. — ^Variant  11. 

Excavation  earth,  cu.  yds.   0,928,- 

756,  at  31^^ $  3,077,914 

Excavation  rock,  cu.  yds.   10,638,- 

010,  at  81^ 8,616,788 

Three  locks 4,751,897 

Wast^way 406,173 

Timber  piers,  cu.  yds.   148,410,  at 

$3.08    457,103 

Clearing  and  grubbing,  acres  384, 

at  $100 38,400 

Clearing,  acres  417,  at  $75 31,275 

Railway  and  telegraph,  18  miles.  .  909,000 

Right  of  way  and  bridges 160,000 

Jetties,  cu.  yds.  264,369,  at  $1.50.  396,554 
Stone  pitching,  sq.  yds.   23,450,  at 

$1.67    39,162 

La  Flor  dam 2,903,804 

Guard  gates 153,416 

Wall  at  Lock  ISTo.  4 241,405 

Western  Division $22,182,891 

Western  Division  . . $22,182,891 

Eastern  Division 45,013,865 

$67,196,756 
Sanitary  and  police.  '  1,000,000 
Lights  and  buoys . . .         500,000 

$68,696,756 
Superintendence  and  engineer- 
ing         4,121,805 

$72,818,561 
Contingencies  20;?^ 14,563,712 

Grand  total $87,382,273 


It  is  believed  that  a  canal  of  this  kind  if  con- 
structed would  be  both  inadequate  and  unstable. 
The  following  are  some  of  the  deficiencies  that 
should  be  supplied  in  order  to  make  it  adequate 
to  the  present  needs  of  commerce:  the  draft 
should  be  increased  from  28  to  30  feet;  the  foun- 
dations of  the  San  Francisco  embankment 
should  be  carried,  down  to  solid  earth,  60  feet  in 
some  cases;  the  Ochoa  dam  should  be  built  of 
masonry  with  its  foundations  on  the  rock;  the 
width  of  the  channel  in  the  San  Juan  river 
should  be  increased  to  300  feet;  several  cut-offs 
should  be  made;  the  minimum  elevation  of  the 
surface  of  Lake  Nicaragua  should  be  reduced  to 
104  feet  above  mean  sea  level  so  as  to  permit  a 
fluctuation  of  6  feet  in  the  surface  of  the  lake; 
the  width  of  the  canal  for  10  miles  on  the  west 
side  should  be  increased  to  200  feet,  and 
waste-ways  provided;  the  La  Flor  dam  should  be 
built  of  masonry  with  its  foundations  on  the 
rock,  or  as  an  alternative,  omitted  entirely  and 
a  "low  level"  route  substituted;  the  harbor  at 
Brito  should  be  modified. 

Menocal  Route. — Variant  L 

Under  your  instructions  an  estimate  has  been 
made  with  these  modifications:  This  plan  is 
called  the  Menocal  route.  Variant  I.  The  route 
is  shown  on  Map  No.  2  and  is  on  the  east  side, 
the  same  as  the  Canal  Company's  route,  just 
considered,  except  some  cut-offs  in  the  San  Juan 
river,  which  both  shorten  and  cheapen  it.  On 
the  west  side  the  route  is  the  same  for  the  first 
10  miles  from  the  lake.  It  then  i)asses  down 
the  south  of  the  valley  of  the  Rio  Grande  and 
the  La  Flor  dam  is  omitted.  This  route  is  some- 
what similar  to  the  "  low  level "  plan  of  the 
Canal  Company. 

The  dimensions  are  those  assigned  by  the 
Commission  for  all  routes.  The  j)rincipal  ones 
are  as  follows:     Depth  of  water  in  the  canal  and 


74 


NICARAGUA  CANAL  COMMISSION 


locks  not  less  than  30  feet  for  all  stages  of  sea, 
lake  and  ocean.  Usable  length  of  locks  620 
feet,  width  of  locks,  80  feet  Width  of  canal  at 
bottom  100  feet  in  rock  cuts;  150  feet  between 
Greytown  and  East  Divide  and  between  Florida 
lagoon  and  Ochoa;  200  feet  through  the  San 
Francisco  and  Florida  lagoons;  and  300  feet  in 
the  San  Juan  river  with*  greater  widths  at  the 
bends.  In  Lake  Nicaragua  the  width  begins  at 
300  feet  and  increases  to  600  feet  at  the  outer 
end.  On  the  west  side  the  width  is  200  feet 
from  the  lake  to  the  first  lock,  then  150  feet 
from  there  to  the  sea.  The  minimum  elevation 
of  the  surface  of  Lake  Nicaragua  is  fixed  at  104 
feet  and  the  maximum  at  110  feet  above  sen 
level.  The  number  of  locks  on  the  east  side  is 
3,  with  lifts  of  36.8  feet  each.  On  the  west 
side  there  are  0  locks  with  lifts  of  19.3  feet 
each. 

The  total  length  of  the  route  between  the 
7-fathom  curves  is  185.32  miles.  The  estimate 
of  cost  is  made  up  as  follows: 

Estimate. 

Caribbean  Sea  to  Pacific  Ocean. 

East  Side. 

Menocal  Eoute. — Variant  I. 

Three  locks. 

Small  harbor  at  Greytown. 
Summit  level  base  at  elevation  74  (Caribbean 
datum). 

Excavation,   earth    87,284,170    cu. 

yds.  at  37ff $32,295,143 

Excavation,    rock    10,157,152    cu. 

yds.  at  93^ 9,446,151 

San  Carlos  embankment,  dry  exca- 
vation, earth  353,600  cu.  yds.  at 
37ff   130,832 

Ochoa  dam  and  controlling  works.  .      6,666,700 

San    Francisco    embankment    and 

dam 4,460,000 


Three  locks,  lift  36.82  feet  at  $2,- 

204,  630 6,613,900 

Guard  gate 172,000 

Sluices   and   weirs,    San    Francisco 

and  Deseado  basins 1,506,000 

Clearing  and  grubbing,  1461  acres 

at  $100 146,100 

Clearing  2460  acres  at  $75 184,500 

Greytown  breakwater,   stone   550,- 

000  cu.  yds.  at  $1.75 962,500 

Timber  work  for  cribs  and  retain- 
ing walls 1,000,000 

Stone  pitching 100,000 

Railroad    complete,    Greytown    to 

Toro  rapids " 4,125,000 

Total,  Eastern  Division $67,808,826 

West  Side. 

Childs  Route. — Variant  I. 

Six-lock  system,  with  summit  level  200  feet 
wide,  remainder  150  feet. 

Small  harbor  at  Brito. 

Excavation,    earth    16,063,377    cu. 

yds.  at  31^ $  4,979,646 

Excavation,    rock    22,625,710    cu. 

yds.  at  81^ 18,326,825 

6  locks  19.33  feet  lift  at  $1,601,250  9,607,500 

1  lock  foundation  in  alluvium 125,000 

Guard  gate 153,000 

Waste-weirs 1,102,300 

Timber  pier  west  side  lake,  151,000 

cu.  yds.  at  $3.08 465,080 

Jetties  Brito  harbor,    144,107    cu. 

yds.  at  $1.50 216,160 

Clearing  and  grubbing,  661  acres  at 

$100   66,100 

Clearing  1127  acres  at  $75 84,525 

Railroad  complete   514,942 

Total  Western  Division $35,641,078 

Total  Western  Division.   $35,641,078 
Total  Eastern  Division.      67,808,826 

$103,449,904 


APPENDIX   I.— HEPORT   OF  THE   CHIEF  ENGINEER 


iO 


Sanitary  and  police. .        1,000,000 
Lights  and  buoys ....  500,000 

$104,949,904 
Superintendence     and 
Engineering,  Q^...       6,296,994 

$111,246,898 
Contingencies,  20^  . .      22,249,380 

Grand  total $133,496,278 


Lull  Routes. 
Lull  Route. — Variant  I. 

An  estimate  has  been  made  of  a  route  which 
follows  the  Lull  route  for  a  portion  of  its  course. 
It  has,  therefore,  been  called  a  Variant  of  the 
Lull  route.     Its  location  is  shown  on  Map  No. 

2.  Leaving  Greytown  harbor  it  passes  north  of 
Lake  Silico  across  the  delta  plain  and  approaches 
the  San  Juan  a  few  miles  above  the  San  Juan- 
illo.  It  then  follows  along  the  north  side  of  the 
San  Juan  to  the  mouth  of  the  San  Carlos,  above 
which  it  enters  the  river.  From  this  point  to 
the  lake  it  follows  the  river  with  a  few  cut-offs 
which  are  shown  on  the  map.  On  the  west  side 
the  route  is  the  same  as  Variant  I  of  the  Childs 
route,  which  has  been  previously  defined.  The 
dimensions  are  also  the  same  except  that  the 
width  from  Greytown  to  the  mouth  of  the  San 
Carlos  is  150  feet  throughout.  The  number  of 
locks  on  the  east  side  is  6,  with  lifts  of  18.4  feet. 

The  number  of  dams  in  the  San  Juan  river  is 

3.  The  total  length  of  the  line  between  the  7- 
fathom  curves  in  the  Caribbean  sea  and  the  Pa- 
cific ocean  is  189.08  miles.  The  estimate  is 
made  up  as  follows: 

East  Side. 
Lull  Route. — Variant  I. 

Six-lock  system  with  3  dams  in  river  (Boca 
San   Carlos,    Conchuda  and   Machuca)   passing 


north  of  Lake  Silico,  includes  small  harbor  at 
Greytown,  lake  dredging  and  curve  widening  on 
river  section.  Summit  level  base  at  elevation 
74  (Caribbean  datum). 

Excavation,  earth   106,441,923  cu. 

yds.  at  37^ $39,383,511 

Excavation,  rock  6,158,160  cu.  yds. 

at  93^  . » 5,727,088 

Clearing,  acres  4100  at  $75 307,500 

Clearing  and  grubbing,  acres  1575 

at  $100 157,500 

Dam  masonry,  concrete  385,529  cu. 

yds.  at  $8.30 3,199,890 

Dam  construction,  not  masonry. . . .  3,395,430 
Four   locks,    lift    18.4    feet,    depth 

48.4  feet 6,406,400 

Two  locks,  lift  18.4  feet,  depth  53.4 

feet 3,414,800 

Waste-weirs 450,300 

Sheet  piling  1,059,800  feet  B.  M. 

at  $60 63,588 

Breakwater    550,000    cu.    yds.    at 

$1.75 "^ 962,500 

Stone  pitching,  120,000  sq.  yds.  at 

$2.00     240,000 

Guard  gate 172,000 

Cribs,  retaining  wall 1,000,000 

Railroad,  complete,  Greytown  to  Sa- 

valos  river \ 2,701,110 

Total  Eastern  Division $67,581,607 

West  Side. 

Childs  Route. — Variant  I. 

Six-lock  system  with  summit  level  200  feet 
wide  and  remainder  150  feet.  Small  harbor  at 
Brito. 

Excavation,    earth    16,063,377    cu. 

yds.  at  SU $  4,979,645 

Excavation,    rock    22,625,710    cu. 

yds.  at  81^ 18,326,825 

Six  locks,  19.33  feet  lift  at  $1,601,- 

250    9,607,500 


76 


NICARAGUA  CANAL  COMMISSION 


One  lock  foundation  in  alluvium. .  125,000 

Guard  gate 153,000 

Waste-weirs    1,102,300 

Timber  pier,  west  side  of  lake  151,- 

000  cu.  yds.  at  $3.08 465,080 

Jetties,  Brito  harbor,   144,107  cu. 

yds.,  stone  at  $1.50 216,160 

Clearing  and  grubbing,  661  acres  at 

$100   •  66,100 

Clearing  1127  acres  at  $75 84,525 

Railroad  complete    514,942 

Total  Western  Division $35,641,078 

Total  Western  Division .   $35,641,078 
Total  Eastern  Division  .      67,581,617 

$103,222,695 
Sanitary  and  police. .  1,000,000 
Lights  and  buoys.  .  .  .  500,000 

$104,722,695 
Superintendence    and 

engineering,  6j^. . .        6,283,361 

$111,006,056 
Contingencies,  20j^  . .     22,201,211 

Grand  total $133,207,267 

Estimates  have  been  made  of  Variants  I,  II, 
III  and  IV  of  Lull  route.  These  estimates 
have  all  started  from  a  common  point  in  the 
Sarapiqui  ridge.  The  dimensions,  number  of 
locks,  etc.,  are  the  same  as  for  the  preceding 
estimate. 

Lull  Eoute. — Variant  I. 

Estimate  of  quantities  for  a  6-lock  system  on 
the  line  passing  north  of  Lake  Silico  between 
Greytown  and  Sarapiqui  ridge.  Length  of  line 
22.324  miles. 

Excavation,    earth    23,406,600    cu. 

yds.  at  37^ $  8,660,442 


Excavation,  rock  1,069,500  cu.  yds. 

at  93ff 994,635 

Greytown     breakwater,     stone     in 

place,  550,000  cu.  yds.  at  $1.75.         962,500 

Eio  Negro  waste-weir,  dry  excava- 
tion, clay  410,000  cu.  yds.  at  37ff.        151,700 

Rio    Negro    waste-weir,    masonry, 

2770  cu.  yds.  at  $8.30 22,991 

Lock  No.  1,  waste-weir,  dry  excava- 
tion, clay  26,000  cu.  yds.  at  37ff .  9,620 

Lock  No.   1,  waste-weir,  masonry, 

250  cu.  yds.  at  $8.30 2,075 

Two  locks  18.414  feet  lift  at  $1,- 

577,000    3,154,000 

One  lock  18.414  feet  lift 1,675,400 

Stone     pitching     on     embankment 

120,000  sq.  yds.  at  $2 240,000 

Clearing,  1500  acres  at  $75 112,500 

Grubbing,  750  acres  at  $100 75,000 

Piers  at  Greytown  harbor  5500  lin. 

ft.  at  $150 825,000 

Total $16,885,863 

Lull  Route. — Variant  11. 

Estimate  of  quantities  for  a  6-lock  system  on 
the  line  through  Lake  Silico  between  Greytown 
and  Sarapiqui  ridge.  Length  of  line  22.068 
miles. 

Excavation,    earth   24,393,700    cu. 

yds.  at  37^ $  9,025,669 

Excavation,  rock  1,368,700  cu.  yds. 

at  93^ 1,272,801 

Greytown     breakwater,     stone     in 

place,  550,000  cu.  yds.  at  $1.75.         962,500 

Eio  Negro  waste-weir,  dry  excava- 
tion, clay  410,000  cu.  yds.  at  37^        151,700 

Eio    Negro    waste-weir,    masonry, 

2770  cu.  yds.  at  $8.30 22,991 

Lock  No.  1,  waste- weir,  dry  excava- 
tion, clay  26,000  cu.  yds.  at  37^ .  9,020 

Lock  No.   1,   waste-weir,  masonry, 

250  cu.  yds.  at  $8.30 2,075 

Two  locks,  lift  18.414  feet  at  $1,- 

577,000    3,154,000 


APPENDIX   I.— REPORT   OF  THE   CHIEF  ENGINEER 


77 


186,600 

112,500 

75,000 


One  lock,  lift  18.414  feet 1,675,400 

Stone    pitching    on    embankments, 

93,300  sq.  yds.  at  $2 

Clearing,  1500  acres  at  $75 

Grubbing,  750  acres  at  $100 

Piers  at  Greytown  harbor,  5500  lin. 

feet  at  $150 825,000 

Total .$17,475,946 

Lull  Route. — Variant  III. 

Estimate  of  quantities  for  a  6-lock  system  on 
the  line  south  of  Lake  Silico  from  harbor  head  to 
Sarapiqui  ridge.     Length  of  line  24.02  miles. 

Excavation,    earth    26,548,100    cu. 

yds.  at  37ff $  9,822,797 

Excavation,  rock  1,231,800  cu.  yds. 

at  93^ 1,145,574 

Harbor  head  breakwater,  stone  in 
place,  550,000  cu.  yds.  at  $1.75 . . 

Rio  Negro  waste-weir,  drj'  excava- 
tion, clay  410,000  cu.  yds.  at  37^ 

Rio  Nc.gro  waste-weir,  masonry, 
2770  cu.  yds.  at  $8.30 

Lock  No.  1,  waste-weir,  dry  excava- 
tion, clay  26,000  cu.  yds.  at  37^ 

Lock  No.  1,  masonry  250  cu.  yds.  at 
$8.30    

Two  locks,  lift  18.414  feet  at  $1,- 

577,000    3,154,000 

One  lock,  lift  18.414  feet 1,675,400 

Stone  pitching  on  embankment 
113,000  sq.  yds.  at  $2 

Clearing,  1650  acres  at  $75 

Grubbing,  825  acres  at  $100 

Pier  at  harbor  head,  5500  lin.  feet 
at  $150 


962,500 

151,700 

22,991 

9,620 

2,075 


226,000 

123,750 

82,500 


825,000 


Total $18,203,907 

Lull  Route. — Variant  IV. 

Estimate  of  quantities  for  a  6-lock  system  on 
the  line  from  Agua  Dulce  along  the  lower  San 
Juan  river  to  Boca  Colorado,  then  across  swamp 
to  Sarapiqui  ridge.     Length  of  line  24.53  miles. 


Excavation,    earth    23,095,100   cu. 

yds.  at  37^ 

Excavation,  rock  570,000  cu.  yds. 

at  93ff 

Agua  Dulce   breakwater,   stone  in 

place  550,000  cu.  yds.  at  $1.75.  . 
Rio  Negro  waste-weir,  dry  excava- 
tion, clay  410,000  cu.  yds.  at  37^, 
Rio    Negro    waste-weir,    masonry, 

2770  cu.  yds.  at  $8.30 

Three  locks,  lift  18.414  feet  at  $1,- 

675,400    

Stone  pitching  194,900  sq.  yds.  at 

$2    .'^ 

Clearing,  1240  acres  at  $75 

Grubbing,  620  acres  at  $100 

Pier  Agua  Dulce,  5500  lin.  feet  at 

$150   


$  8,545,187 

530,100 

962,500 

151,700 

22,991 

5,026,200 

389,800 
93,000 
62,000 

825,000 


Total $16,608,478 

If  each  of  these  partial  routes  be  combined 
with  the  total  estimate  of  the  Lull  Variant  I,  the 
following  are  obtained: 

Lull  Route. — Variant  I. 

Total  cost  of  route  north  of  Silico. $133,207,267 
Length  189.98  miles  (see  page  76). 

Lull  Route. — Variant  II. 

Through  Silico $133,957,853 

Length  189.76   miles. 

Lull  Route. — Variant  III. 

South  of  Silico $134,883,819 

Length  191.75  miles. 

Lull  Route. — Variant  IV. 

Agua  Dulce  • $132,854,433 

Length  192.25  miles. 

The  route  through  Agua  Dulce  is  a  little  the 
cheapest  of  the  four,  but  it  is  two  miles  longer 


78 


NICARAGUA  CANAL  COMMISSION 


and  is  rejected  on  that  account.  The  route 
through  Lake  Silico  is  one-quarter  of  a  mile 
shorter  than  the  northern  route,  but  costs  a  half 
a  million  more.  It  is  therc^fore  rejected.  The 
route  soutli  of  the  lake  is  longer  and  more  ex- 
pensive than  the  northern  one,  it  is  therefore  re- 
jected and  the  northern  one  selected.  The  small 
difference  in  the  cost  of  thej?e  various  routes 
shows  that  choice,  so  far  as  cost  alone  is  con- 
cerned, is  practically  immaterial.  The  northern 
route  has  in  addition  some  advantages  over  the 
others,  for  example,  it  can,  without  additional 
cost,  be  made  to  enter  the  sea  near  Tndio  river. 
This  may  prove  desirable.  This  completes  the 
estimate  of  the  proposed  locations. 

Locks. 

So  far,  for  the  purposes  of  comparison,  6-lock 
svstems  have  been  considered  on  botli  the  east 
and  west  sides. 

An  attempt  will  now  be  made  to  determine 
the  most  desirable  number  of  locks.  Tlie  east 
and  west  sides  will  be  considered  separately. 

In  anv  svstem  of  locks  there  are  some  advan- 
tages  in  having  the  dimensions  of  all  the  locks 
uniform.  The  lift  for  each  lock  in  any  system 
has  been  found  by  dividing  the  total  lift  by  the 
number  of  locks  in  the  system.  The  total  lift 
on  the  east  side  from  low  water  in  the  Caribbean 
sea  to  high  water  in  Lake  Nicaragua  being  110.5 
feet,  the  lift  of  a  single  lock  in  a  5-lock  system 
is  22.1  feet;  in  a  6-lock  system  18.4  feet;  in  a 
7-lock  system  15.8  feet;  and  in  an  8-lock  system 
13.8  feet. 

The  number  of  dams  in  the  San  Juan  river  is 
also  variable.  Systems  of  1,  2,  and  3  dams  have 
been  considered.  A  single  dam  at  the  mouth  of 
the  San  Carlos  river  would  have  a  head  of  55 
feet  in  ordinary  stages  of  water.  In  a  system  of 
2  dams,  each  dam  would  have  a  head  of  27.5 


feet  and  in  a  system  of  3  dams  that  head  would 
be  18.4  feet 

Estimates  have  been  made  of  the  cost  of  5,  6, 
7  and  8-lock  systems  on  the  east  side,  and  each 
one  of  these  has  been  combined  with  systems  of 
2  and  3  dams.     The  results  are  as  follows: 

Estimates. 

« 

Lake  Xicaragua  to  Caribbean  Sea. 

Totals,  various  systems  with  one  to  three  dams 
in  river.  Passing  north  of  Lake  Silico  and  in- 
cluding small  harbor  at  (Ireytown,  lake  dredg- 
ing and  curve  widening  on  river  section.  Sum- 
mit level  74  (Caribbean  datum). 

5-Lock  System,  1  dam  in  river.  . .  .$65,852,817 
5-Lock  System,  2  dams  in  river. .  .  67,354,539 
5-Lock  Svstem,  3  dams  in  river. .  .Not  feasible. 

6-Lock  System,  1  dam  in  river $63,240,141 

6-I^ck  System,  2  dams  in  river. .  .  64,812,470 
6-Lock  System,  3  dams  in  river.  . .    67,581,610 

7-Lock  System,  1  dam  in  river 62,669,099 

7-Lock  System,  2  dams  in  river.  .  .  63,818,731 
7-Lock  System,  3  dams  in  river.  .  .    67,411,672 

8-Lock  System,  1  dam  in  river.  .  . .  66,829,093 
8-Lock  System,  2  dams  in  river. .  .  68,780,662 
8-Lock  System,  3  dams  in  river.  .  .    71,157,210 

On  the  west  side  the  total  lift  from  low  water 
in  the  Pacific  ocean  to  high  water  in  Lake  Nica« 
ragua  is  115.5  feet. 

In  a  system  of  4  locks  the  lift  for  each  lock 
would  be  28.9  feet;  5  locks  would  be  23.1  feet, 
and  6  locks  would  be  19.3  feet.  Estimate  of 
cost  of  4,  5  and  6-lock  systems  have  been  made 
and  are  as  follows: 

West  Side. 

Childs  Eoute. — Variant  I. 

Four-lock  system  with  summit  level  200  feet 
wide  and  remainder  150  feet.  Small  harbor  at 
Brito. 


APPENDIX   I.— REPORT   OF   THE   CHIEF   ENGINEER 


79 


Excavation,    earth    10,226,281    cii. 

yds.  at  31^ 

Excavation,    rock    23,099,488    cu. 

yds.  at  81^ 

Four  locks,  29  ft.  lift  at  $1,853,1-45 

Guard  gate 

Waste-weir 

Timber  pier,  west  side  of  lake,  151,- 

000  cu.  yds.  at  $3.08 

Jetties,  Brito  harbor,  stone  144,107 

cu.  vds.  at  $1.50 

Clearing  and  grubbing,  acres  661  at 

$100   ...  .! 

Clearing,  acres  1127  at  $75 

Railroad  complete   


$  5,030,147 

18,710,585 

7,412,580 

153,000 

1,102,300 

465,080 

216,160 

66,100 

84,525 

514,942 


Total  AVesteni  Division $33,755,419 


West  Side. 

Cliilds  Eoutc. — Variant  I. 

Five-lock  system  with  summit  level  200  feet 
wide  and  remainder  150  feet.  Small  harbor  at 
Brito. 

Excavation,    earth    16,372,379    cu. 

yds.  at  31ff $  5,075,623 

Excavation,    rock    22,923,053    cu. 

yds.  at  81^ 18,567,673 

Five  locks,  23.2  feet  lift  at  $1,701,- 

900   8,509,500 

One  lock  foundation  in  alluvium.  .         125,000 

Guard  gate 153,000 

Waste-weirs 1,102,300 

Timber  piers  west  side  of  lake  151,- 

000  en.  yds  at  $3.08 465,080 

Jetties,  Brito  harbor,  stone  144,107 

cu.  yds.  at  $1.50 216,160 

Clearing  and  grubbing,  acres  661  at 

$100 66,100 

Clearing,  acres  1127  at  $75 84,525 

Railroad  complete   514,942 


West  Side. 
Childs  Route. — Variant  I. 

Six-lock  system  with  summit  level  200  feet 
wide  and  remainder  150  feet.  Small  harbor  at 
Brito. 

Excavation,    earth    16,063,377    cu. 

yds.  at  31^ $  4,979,646 

Excavation,    rock    22,625,710    cu. 

yds.  at  81^ 18,326,825 

Six  locks,  19.33  feet  lift  at  $1,601,- 

250 9,607,500 

One  lock  foundation  in  alluvium .  .         125,000 

Guard  gate 153,000 

Waste-weirs    1,102,300 

Timber  pier,  west  side  of  lake,  151,- 

000  cu.  yds.  at  $3.08 

Jetties,  Brito  harbor,  stone  144,107 

cu.  vds.  at  $1.50 

Clearing  and  grubbing,  acres  661  at 

$100   

Clearing,  acres  1127  at  $75 

Railroad   


465,080 
216,160 


66,100 

84,525 

514,942 


Total  Western  Division $34,879,903 


Total  Western  Division $35,641,078 

This  completes  the  estimates.  They  are  in- 
tended to  include  all  the  characteristic  variants, 
both  in  location  and  construction.  It  yet  re- 
mains to  point  out  their  relative  merits  and  de- 
fects and  to  select  the  one  which  seems  most  de- 
sirable. 

The  Menocal  plan,  as  has  been  previously 
pointed  out,  is  both  inadequate  and  unstable. 
The  variants  of  this  plan,  though  adequate,  are 
unsafe.  For  example,  one  feature  of  the  plan 
is  an  artificial  lake  of  nearly  100  square  miles 
in  area  and  60  feet  deep  in  places  and  retained 
by  dams  and  earth  embankments  having  a 
length  of  more  than  10  miles.  A  single  well- 
placed  charge  of  dynamite  might  break  through 
the  crest,  in  which  case  the  whole  delta  plain  of 
the  San  Juan  river  would  be  inundated.     There 


80 


NICARAGUA  CANAL  COMMISSION 


might  be  great  loss  of  life  and  it  is  not  probable 
that  the  canal  could  be  used  again  in  less  than 
three  years. 

It  does  not  seem  advisable  to  place  such  tre- 
mendous possibilities  within  easy  reach  of  the 
malice  of  an  enemy  or  the  caprice  of  a  madman. 

The  plan  of  a  single  dam  at  the  mouth  of  the 
San  Carlos  is  open  to  the  same  objection,  though 
in  a  much  less  degree.  In  this  case  an  artificial 
lake  is  formed  having  an  area  of  48  square  miles 
and  a  maximum  depth  of  55  feet,  much  land, 
both  in  Costa  Rica  and  Nicaragua,  that  might 
become  valuable,  would  be  submerged.  The 
cost,  however,  is  about  $5,000,000  less  than  for 
a  system  of  3  dams,  and  this  might  be  deemed 
sufficient  to  govern. 

The  plan  of  3  dams  in  the  river  practically 
eliminates  the  danger  from  floods  that  might  be 
caused  by  the  failure  of  dams,  because  the  pools 
of  impoimded  water  are  small  in  area  and  have 
a  maximum  depth  of  only  18  feet.  If  one  of 
these  should  be  suddenly  discharged  into  the 
river  it  would  cause  a  temporary  rise  of  only  a 
few  feet.  The  maximum  unit  pressure  on  a 
system  of  3  dams  is  only  one-third  as  great  as  for 
a  single  dam.  For  these  reasons  a  system  of  3 
dams  is  preferred. 

With  3  dams  in  the  river  a  system  of  7  locks 
is  slightly  cheaper  than  any  other,  the  difference 
between  it  and  a  G-lock  system  is  only  $170,000. 

The  cost  of  operating  a  lock  is  estimated  at 
$40,000  annually.  This,  if  capitalized  at  4  per 
cent,  would  add  $1,000,000  to  the  first  cost, 
which  would  make  the  7-lock  system  more  ex- 
pensive than  the  6. 

The  6-lock  svstem  with  3  dams  in  the  river, 
is  therefore  chosen  for  the  east  side. 

On  the  west  side  three  systems  of  locks  have 
been  considered.  Their  relative  costs  are  as  fol- 
lows: 


4  Locks $33,755,000 

5  Locks 34,879,900 

6  Locks 35,641,000 

The  4-lock  system  is  the  cheapest  of  the  three. 
The  lift  in  each  lock  is  28.9  feet.  This  large 
lift  is  objectionable.  Again  its  capacity  for 
passing  boats  is  13  per  cent,  less  than  that  of 
the  6-lock  system  on  the  east  side.  It,  however, 
has  the  advantage  of  having  rock  foundations 
for  all  its  lock  sites. 

In  order  to  make  the  systems  comparable  with 
each  otTier,  the  capitalized  cost  of  operating  the 
additional  locks  should  be  included.  If,  then, 
we  add  to  the  5-lock  system  $1,000,000,  and  to 
the  6-lock  system  $2,000,000,  their  cost  can  be 
compared  with  the  4-lock  system.  This  leaves 
the  4-lock  system  decidedly  the  cheaper  of  the 
three. 

Since  it  is  unlikely  that  any  system  of  locks 
would  be  pushed  to  its  full  capacity  during  the 
first  years  of  use  and  also  since  it  is  likely  that 
a  duplicate  system  of  locks  would  soon  be  con- 
structed, the  4-lock  system  has  been  chosen  for 
the  present 

A  canal  with  one  dam  in  the  river,  6  locks 
on  the  east  side,  4  locks  on  the  west  side  and 
small  waste-way  to  the  Pacific  has  been  esti- 
mated  for  as  follows: 

Estimate. 

Caribbean  Sea  to  Pacific  Ocean. 

6-Lock  system  east  side.    4-Lock  system  west  side. 

East  Sede. 

Lull  Route. — Variant  I. 

Six-lock  system,  one  dam  in  river  (Boca  San 
Carlos)  passing  north  of  Lake  Silico,  includes 
small  harbor  at  Greytown,  lake  dredging  and 
curve  widening  on  river  section.  Summit  level 
74  (Caribbean  datum). 


APPENDIX   I.— REPORT   OF  THE   CHIEF  ENGINEER 


81 


Excavation,  earth  102,099,463  cu. 

yds.  at  37^ $37,776,801 

Excavation,  rock  5,490,770  cu.  yds. 

at  93ff \  .  .     5,106,416 

Clearing  and  grubbing,  acres  1575 

at  $100 157,500 

Clearing,  acres  4100  at  $75 307,500 

Dam,  concrete   4,570,340 

Six  locks 9,560,400 

Waste-weirs    456,386 

Sheet  piling  3,819,800  ft.  B.  M.  at 

$60 229,188 

Breakwater    550,000    cu.    yds.    at 

$1.75    ' 962,500 

Stone  pitching  120,000  sq.  yds.  at  • 

$2    * 240,000 

Guard  gate 172,000 

Pier  Greytown 1,000,000 

"Railroad  complete,  Greytown  to  Rio 

Sahalos   .' 2,701,110 

Total  Eastern  Division $63,240,141 

West  Side. 

Childs  Eoute. — Variant  I. 

Four-lock  system.     150  feet  w^ide  throughout. 
Small  harbor  at  Brito. 

Earth    excavation    15,500,530    cu. 

yds.  at  31ff $  4,805,164 

Rock  excavation  18,081,334  cu.  yds. 

at  81ff 14,645,881 

Four  locks,  29  ft.  lift,  at  $1,853,145  7,412,580 

Guard  gate 153,000 

Waste-weirs 1,102,300 

Timber  piers,  west  side  of  lake,  151,- 

000  cu.  yds.  at  $3.08 465,080 

Jetties,  Brito  harbor,  stone  144,107 

cu.  yds.  at  $1.50 216,160 

Clearing  and  grubbing,  acres  661  at 

$100 66,100 

Clearing,  acres  1127  at  $75 84,525 

Railroad  complete   514,942 

$29,465,732 
6 


Total  Western  Division . .  $29,465,732 
Total  Eastern  Division  .  .    63,240,141 


$92,705,873 

Sanitary  and  police 1,000,000 

Lights  and  buoys 500,000 


$94,205,873 
Superintendence      and 

engineering,  6j^. . . .      5,652,352 


$99,858,225 
Contingencies,  20j^  ...   19,971,645 


$119,829,870 


This  plan  is  the  cheapest  of  any  that  has 
been  considered,  but  it  includes  a  high  dam  in 
the  San  Juan  river  and  an  insufficient  waste-way 
on  the  west  side,  therefore,  for  reasons  already 
given,  it  is  not  preferred. 

The  preferred  location  and  plan  of  construc- 
tion are  then  as  follows: 

The  route  on  the  east  side  is  shown  on  the 
map  as  *^  Lull  Route,  Variant  L"  It  passes 
north  of  Lake  Silico,  enters  the  San  Juan  river 
above  the  mouth  of  the  San  Carlos,  follows  the 
river  with  some  cut-offs  to  Lake  jSTicaragua, 
crosses  the  lake  to  the  mouth  of  the  Lajas.  On 
the  west  side  it  is  shown  as  "  Childs  Route,  Va- 
riant I."  It  passes  up  the  valley  of  the  Lajas, 
crosses  the  Continental  Divide,  enters  the  valley 
of  the  Rio  Grande  and  follows  down  its  southern 
side  to  Brito. 

Its  construction  contemplates  harbors  at  Grey- 
town and  Brito  .with  safe  entrances,  but  small 
interior  basins,  6  locks  on  the  east  side  with  3 
dams  in  the  San  Juan  river,  4  locks  on  the  west 
side  and  waste-way  to  the  Pacific  with  a  mean 
capacity  of  33,000  cubic  feet  per  second.  The 
proposed  sites  of  harbors,  locks,  dams  and  waste- 
ways  are  shown  on  the  map. 


82 


NICARAGUA  CANAL  COMMISSION 


It  is  neither  the  shortest  route  nor  the  cheap- 
est plan,  but,  for  reasons  given,  it  is  preferred. 
Its  estimated  cost  is  as  follows: 

Estimate. 

Caribbean  Sea  to  Pacific  Ocean. 

6-Lock  system  east  side.  4-Lock  system  west  side. 

Lull  Route. — Variant  I. 

Six-lock  system  with  3  dams  in  river  (Boca 
San  Carlos,  Conchuda  and  Machuca)  passing 
north  of  Lake  Silico,  includes  small  harbor  at 
Greytown,  lake  dredging  and  cun-e  widening  on 
river  sections.  Summit  level  at  elevation  74 
(Caribbean  datum). 

Excavation,  earth  106,441,923  cu. 

yds.  at  37^ $39,383,511 

Excavation,  rock  6,158,100  cu.  yds. 

at  93^ 5,727,088 

Clearing,  acres  4100  at  $75 307,500 

Clearing  and  grubbing,  acres  1575 

at  $100 157,500 

Dam    masonry,    concrete,    cu.    yds. 

385,529  at  $8.30 3,199,890 

Dam  construction  not  masonry. . . .      3,395,430 
Four    locks,    lift    18.4    ft.,    depth 

48.4  ft 6,406,400 

Two  locks,  lift  18.4  ft.,  depth  53.4 

ft 3,414,800 

Waste-weirs    450,300 

Sheet  piling,  feet  B.  M.  1,059,800 

at  $60  per  M 63,588 

Breakwater,    cu.    yds.    550,000    at 

$1.75     962,500 

Stone  pitching,  sq.  yds.  120,000  at 

$2    240,000 

Guard  gate 172,000 

Cribs,  retaining  walls 1,000,000 

Railroad  complete,  Greytown  to  Sa- 

balos  river 2,701,110 


West  Side. 

Childs  Koute. — Variant  I. 

Four-loi.»k  svstem  with  summit  level  200  feet 
wide  and  remainder  150  feet.  Small  harbor  at 
Brito. 

Excavation,    earth    16,226,281    cu. 

yds.  at  31^ $  5,030,147 

Excavation,    rock    23,099,488    cu. 

yds.  at  81^ 18,710,585 

Four  locks,  29  ft.  lift  at  $1,853,145  7,412,580 

Guard  gate 153,000 

Waste-weirs 1,102,300 

Timber  pier,  west  side  of  lake  151,- 

000  cu.  yd?,  at  $3.08 465,080 

Jetties,  Brito  harbor,  stone  144,107 

cu.  yds.  at  $1.50 216,160 

Clearing  and  grubbing,  acres  661  at 

$100   66,100 

Clearing,  acres  1127  at  $75 84,525 

Railroad  complete   514,942 


Total,  Western  Division $33,755,419 

Total  Western  Division.  .$33,755,419 
Total  Eastern  Division  . .   67,581,617 


$101,337,036 
Sanitary  and  police.  .  1,000,000 
Lights  and  buoys.  . .  .  500,000 


$102,837,036 
Superintendence     and 

engineering  add  6^       6,170,222 


$109,007,258 
Contingencies  add  20^    21,801,451 


Total  Eastern  Division $67,581,607 


Grand  total $130,808,700 

There  are  some  additional  conditions  bearing 
upon  the  cost  and  order  of  construction  that  may 
be  considered  here. 

The   assumed    dimensions   of   the   canal   are 


APPENDIX  I.— REPORT   OF  THE   CHIEF  ENGINEER 


83 


larger  in  tlie  aggregate  than  any  hitherto  pro- 
posed. They  are  supposed  to  be  sufficient  for 
the  growing  needs  of  commerce  for  a  term  of 
years,  perhaps  20.  It  is  known  that  large 
canals,  such  as  St.  Mary's  Falls,  Manchester  and 
Suez,  had  comparatively  little  business  during 
the  first  years  of  their  \ise.  It  is  safe  to  assume 
that  if  the  Nicaragua  Canal  should  be  built,  its 
business  would  be  relatively  small  at  first,  and 
that  if  adequate  to  do  the  business  for  20  years 
it  would  at  first  have  a  capacity  largely  in  excess 
of  its  needs.  It  is  possible,  and  even  probable, 
that  a  canal  100  feet  wide  in  earth  and  rock 
cuts,  and  150  feet  wide  in  the  river,  with  suit- 
able passing  places  would  do  all  the  business 
that  came  to  it  for  the  first  few  years.  The 
widening  of  the  channel  could  be  done  when 
the  needs  of  commerce  demanded  it  and  at  no 
greater  cost  than  if  done  at  first  Wooden  locks 
could  be  used  at  first;  there  is  even  a  possibility 
that  thov  would  be  better  in  the  end  than 
masonr\'  locks.  They  would  certainly  answer 
for  the  first  set,  until  duplicate  ones  were  neces- 
sary. An  estimate  has,  therefore,  been  made  of 
a  canal  with  nan*ow  channels  and  wooden  locks. 
The  estimated  cost  is  as  follows: 

Estimate. 

Caribbean  Sea  to  Pacific  Ocean. 

6-Lock  system  east  side.    4-Lock  system  west  side. 

East  Side. 

Lull  Eoute. — ^Variant  I. 

Six-lock  system  (timber)  3  dams  in  river  (Low- 
er [Machuca,  Conchuda  and  Boca  San  Carlos) 
passing  north  of  Lake  Silico,  including  small 
harbor  at  Greytown  and  lake  dredging.  Kivcr 
section  150  feet  wide,  balance  of  canal  100  feet. 
Summit  level  74  CCaribbean  datum). 


Excavation,    earth    78,251,986   cu. 

yds.  at  37^ $28,953,234 

Excavation,  rock  4,573,027  cu.  yds. 

at  93^ 4,252,914 

Clearing,  acres  4100  at  $75 307,500 

Clearing  and  grubbing,  acres  1575 

at  $100 157,500 

Dam,  masonry  (concrete)   385,529 

cu.  yds.  at  $8.30 3,199,890 

Dam  construction  other  than  ma- 
sonry        3,395,430 

Two  locks,  depth  53.4  ft.,  lift  18.4 

ft 2,000,000 

Four  locks,  depth  48.4  ft.,  lift  18.4 

ft 3,818,824 

Waste-weirs 450,280 

Sheet  piKng,  ft.  B.  M.  1,059,800  at 

$60  per  M 63,588 

Breakwater,    550,000    cu.    yds.    at 

$1.75   962,500 

Stone  pitching,  120,000  sq.  yds.  at 

$2   240,000 

Guard  gate 172,000 

Piers,  Greytown 1,000,000 

Railroad,  Greyto^vn  to  Rio  Sabalos     2,701,110 

Total,  Eastern  Division $51,674,776 

West  Side. 

Childs  Route. — Variant  I. 

Four-lock  system  (timber)  summit  level  200 
feet  wide.  Remainder  of  canal  100  feet  wide, 
except  at  passing  points  which  are  150  feet  wide. 
Small  harbor  at  Brito. 

Excavation,    earth    14,966,500    cu. 

yds.  at  31^ $  4,639,615 

Excavation,    rock    21,310,967    cu. 

yds.  at  81^ .' 17,261,883 

Four  locks,  lift  29  ft.  at  $1,220,000  4,880,000 

Lock  foundation  in  alluvium 125,000 

Guard  gate 153,000 

Waste-weirs 1,102,300 

Timber  pier,  west  side  lake  151,000 

cu.  yds.  at  $3.08 465,080 


84 


NICARAGUA  CANAL  COMMISSION 


Jetties,  Brito  harbor,  stone  144,107 

cu.  yds.  at  $1.50 216,160 

Clearing  and  grubbing,  acres  661 

at  $100 66,100 

Clearing,  acres  1127  at  $75 84,525 

Kailroad   514,942 

Total  Western  Division $29,508,605 

Total  Eastern  Division  .  .$51,674,778 
Total  Western  Division. .   29,508,605 

$81,183,383 
Sanitary  and  police.  .  .  1,000,000 
Lights  and  buoys 500,000 

$82,683,383 
Superintendence     and 

engineering,  6ji    ...     4,961,003 

$87,644,386 
Contingencies,  20j^  ...   17,528,877 

Grand  total $105,173,263 

This  estimate  has  been  made  without  any 
change  of  location  or  plan.  The  only  dimen- 
sion that  has  been  changed  is  the  width  of  the 
canal.  The  material  in  the  locks  has  been 
changed  from  concrete  to  wood. 

It  is  thus  possible  to  so  arrange  the  order  of 
construction  that  the  use  of  the  canal  can  be- 
gin when  an  expenditure  of  $105,000,000  has 
been  made.  The  remaining  $25,000,000  of  ex- 
penditure need  not  be  made  until  commerce  de- 
mands it.  This  order  of  construction  should,  in 
my  opinion,  be  followed. 

In  preparing  this  report  all  available  data  have 
been  used;  its  weight  upon  different  points  is  va- 
riable, and  an  attempt  has  been  made  to  point 
this  out  in  the  body  of  the  report.  It  will  be 
given  again  here  in  compact  form,  so  that  the 
relative  "weight  and  value  of  the  various  conclu- 
sions may  be  fully  understood. 


First  the  field  work  is  all  of  good  quality, 
there  are  no  weak  or  doubtful  parts;  as  far  as  it 
professes  to  go,  it  is  entirely  trustworthy.  The 
many  difficulties  in  the  way  of  doing  the  field 
work  served  only  to  retard  its  accomplishment, 
but  did  not  in  any  way  lower  its  quality.  In 
amount  it  is  sufficient  for  preliminarj"  estimates. 
It  is  not  and  was  not  intended  to  be  minute 
enough  for  the  preparation  of  specifications  and 
final  exact  locations.  The  computation  of  quan- 
tities has  been  made  and  checked  with  the  care 
usual  in  such  work,  and  the  totals  are  entirely 
trustworthy.  The  relative  amounts  of  earth  and 
rock  have  been  derived  from  a  line  of  borings 
along  the  proposed  line  of  the  canal.  These 
borings  in  important  places  ai*e  usually  not  more 
than  three  thousand  feet  apart.  It  is  believed 
that  the  relative  amounts  as  given  will  not  prove 
to  be  much  in  error.  The  unit  prices  for  exca- 
vation and  locks  have  been  obtained  by  compar- 
ison with  the  known  cost  of  the  Chicago  Drain- 
age Canal  and  the  locks  in  the  St.  ^Mary's  Falls 
Canal. 

Up  to  this  point  there  can  be  no  large  error, 
at  least  no  larger  than  would  enter  into  the  esti- 
mates for  a  second  drainage  canal  near  Chicago 
or  an  additional  lock  at  Sault  Ste.  Marie. 

The  next  step  is  to  assign  the  difference  be- 
tween the  cost  of  work  done  in  the  United 
States  and  similar  work  done  in  Nicaragua.  In 
this,  there  is  a  large  amount  of  uncertainty. 
The  Panama  Canal  is  the  onlv  similar  work  in 
this  region.  For  obvious  I'easons  it  cannot  be 
used  for  comparison.  Again,  comparison  with 
work  in  Central  America  done  bv  native  labor 
would  bo  misleading,  for  this  is  sometimes  al> 
normally  cheap.  Comparisons  have  been  made 
with  such  works  as  are  large  enough  to  require 
imported  labor.  The  results  are  not  accordant, 
but  the  following  limits  seem  reasonably  certain. 


APPENDIX   I.— REPORT   OF   THE   CHIEF  ENGINEER 


85 


The  excess  of  cost  in  Central  America  would  not 
be  less  than  twenty-five  per  cent,  and  would  not 
be  greater  than  one  hundred  per  cent  These 
are  wide  limits,  but  the  information  at  present 
available  does  not  seem  to  me  sufficient  to  make 
them  any  smaller.  I  have  assigned  different 
percentages  to  different  parts  of  the  work  for 
reasons  given.  In  the  aggregate  it  is  assumed 
that  the  work  in  Mcaragua  will  cost  about  sixty 
per  cent,  more  than  similar  work  in  the  United 
States.  This  is  but  little  more  than  an  opinion, 
which  may  be  changed  at  any  time  upon  better 
information. 

These  estimates  have  been  made  for  the  con- 
ditions deemed  most  likely  to  occur;  unlikely 
conditions,  though  possible,  have  not  been  con- 
sidered: for  example,  an  exceptionally  healthy 
period,  or  a  period  in  which  the  prices  of  labor 


and  material  were  below  the  average,  has  not 
been  assumed ;  these  would  tend  to  make  the  cost 
of  the  work  less.  On  the  other  hand  a  corrupt 
administration  or  a  season  of  pestilence  would 
make  the  cost  of  the  work  more,  but  these  possi- 
bilities are  remote  and  have  not  been  considered. 

The  estimates  are  intended  to  be  the  most 
probable,  that  is,  they  are  equally  likely  to  be 
small  or  large. 

I  have  the  honor  to  transmit  herewith,  the 
special  reports  of  Assistant  Engineers,  C.  W. 
Hayes,  A.  P.  Davis,  J.  W.  G.  Walker,  F.  L. 
Stuart,  H.  H.  Trundle,  Boyd  Ehle,  S.  S.  Evans, 
Stephen  Harris,  Andrew  Onderdonk,  and  L. 
Hankins. 

Very  respectfully, 

E.  S.  Wheelee, 
Chief  Engineer,  Nicaragua  Canal  Commission. 


APPENDIX  11 


REPORT 


ON  THE 


GEOLOGY  AND  PHYSIOGRAPHY 


OF  THE 


NICARAGUA  CANAL  ROUTE 


BY 

CHARLES  WILLARD  HAYES 

Geologist,  U.  S.  Geological  Survey. 


CONTENTS 

Letter  of  Transmittal. 

PAGB 

Personnel  of  the  Party 93 

Drilling  Operations   93 

General  Geologic  Work 94 

Scope  of  the  Report 94 

PART  1 

PHYSIOGRAPHY  AND  GEOLOGY  OF  THE  CANAL  REGION. 

Topography. 

The  Nicaraguan  Depression 95 

Classification  of  Topographic  Features 95 

The  Alluvial  Plains 97 

The  Dissected  Peneplain 100 

The  Residual  Hills 105 

The  Western  Divide 106 

Regions  Adjacent  to  the  Nicaraguan  Depression 107 

The  Lake— Caribbean  Divide 107 

Volcanic  Mountain  Ranges 108 

Volcanic  Plateaus 110 

Climate. 

9 

Amount  and  Distribution  of  Rainfall Ill 

Physiographic  Effects    112 

Eastern  Division    112 

Western  Division 113 

Rock  Formations. 

Conditions  for  Study 114 

Classification  of  the  Rocks 114 

Brito  Formation 114 

Distribution    114 


90  NICARAGUA  CANAL  COMMISSION 

PAGE 

Lithologic  Character    114 

Structure    115 

,  Utilization 117 

Age  of  the  Foiination 117 

Machuca  Formation 117 

Distribution ■. 117 

Lithologic  Character    118 

Structure    118 

Utilization 118 

Age  of  the  Formation 119 

Tertiary  Igneous  Rocks 119 

Massive  Igneous  Rocks 120 

Fragmental  Igneous  Rocks 121 

Recent  Alluvial  Formations 122 

Recent  Volcanic  Rocks 123 

Rock  Decay. 

Importance  of  the  Subject 124 

Conditions  Favoring  Rock  Decay 125 

Effect  of  Chemical  Composition 125 

Effect  of  Original  Structure 126 

Effect  of  Secondary  Structures 127 

Rock  Decay  in  the  Eastern  Division 127 

Products  of  Rock  Decay 128 

Red  Clav    128 

Blue  Clay 129 

Soft  rock  (saprolite) 129 

Rock  Decay  in  the  Western  Division 130 

Earthquakes. 

Relation  of  the  Canal  Route  to  Centers  of  Volcanic  Activity 132 

Considerations  Affecting  Earthquake  Forecasts    133 

Seismic  records  in  the  Canal  Region 136 

Recent  Gdologic  History. 

Conditions  Anterior  to  Tertiary  Time 138 

Early  Tertiary  Deposition  and  Volcanic  Activity 138 

Middle  Tertiary  Uplift  and  Erosion 139 

Post-Tertiary  Elevation  and  Gorge  Cutting 140 


APPENDIX  II.— GEOLOGIC   REPORT  9][ 

PAGE 

Recent  Depression  and  AUuviation 143 

Formation  of  Lake  Nicaragua 144 

Subsequent  Modification  of  the  Lake 146 

Physiography  of  the  San  Juan  Valley. 

Physiographic  Subdivisions  of  the  River  and  Valley 148 

The  Upper  Division 149 

The  Middle  Division 149 

The  Lower  Division 151 


PART  II 

APPLICATION  OF  GEOLOGIC  FACTS  TO  ENGINEERING  PROBLEMS. 

Classification  of  !&La.teeials. 

Alluvium    153 

Residual  Clay 155 

Soft  Rock 155 

Hard  Rock 158 

Factoes  Determining  Relative  Cost  of  Excavating  Hard  Rock, 160 

Character  of  Data  on  which  Geologic  Sections  are  Based. 

Boring  Operations 161 

Surface  Examinations 161 

Records  of  Canal  Company's  Borings 162 

Geologic  Details. 

Western  Division 162 

La  Flor  Dam  Site 162 

Rio  Grande  Dam  Site 163 

Brito 164 

Excavation  Lines,  Lake  Nicaragua  to  Pacific  Ocean    165 

Dam  Sites  on  the  Rio  San  Juan 167 

Castaio 167 

Upper  Machuca   167 

Machuca 167 

Conchuda 168 

Boca  San  Carlos 169 

Ochoa 169 


92  NICARAGUA   CANAL  COMMISSION 

PAQB 

I^wer  Ochoa 170 

Tambor  Grande    171 

Embankment  Lines   171 

San  Carlos   171 

San  Francisco 172 

Tamborcito  Point 172 

Tamborcito  Lagoon 173 

Excavation  Lines,  Eastern  Division 173 

Eiver  Section  (Lull  Route),  Lake  Nicaragua  to  Boca  San  Carlos 173 

Menocal  Route 175 

Variants  of  the  Lull  Route 177 

Additional  Geologic  Work  Required  for  Final  Location. 

On  Excavation  Lines 182 

On  Foundations 183 


PART  111 

MICROSCOPIC  PETROGRAPHY  OF  THE  ROCKS  FROM  THE  NICARAGUA 

CANAL  REGION. 

By  F.  LESLIE  RANSOME 

Asst.  Geologist,  U.  S.  G.  S. 


APPENDIX  II 


Mr.  E.  S.  Wheeler,  Chief  Engineer,  Nica- 
ragua Canal  Commission,  Washington, 
D.  C. 

Sir: — I  have  the  honor  to  submit  herewith  a 
report  of  my  work  for  the  Nicaragua  Canal 
Commission,  carried  on  under  your  direction. 
In  accordance  with  your  letter  of  instructions, 
dated  December  21,  1897,  received  at  Grey- 
town,  Nicaragua,  I  assumed  immediate  charge 
of  the  geological  party.  The  \york  of  that 
party  included  drilling  operations  as  well  as  a 
generaUgeologic  and  physiographic  study  of  the 
region  adjacent  to  the  route  of  the  proposed 
canal. 

Personnel  of  the  Party. — The  following 
men  were  assigned  to  the  party  under  my  charge: 
Ignatius  O'Reardon,  as  general  assistant;  Harry 
Spence  and  Patrick  Tierney,  as  chief  drillers; 
T.  J.  II.  Archambault,  Moriz  Bernstein,  W.  E. 
Herbert,  E.  F.  Fischer,  and  E.  P.  Humphrey,  as 
drillers.  Mr.  Humphrey  was  detached  from 
the  party  and  ordered  to  report  to  Assistant  En- 
gineer Walker  on  the  15th  of  Febniary,  1898. 
On  the  13th  of  August  George  H.  Seymour  was 
added  to  the  party,  and  on  September  1,  W.  A. 
Smith  and  A.  H.  Miller.  With  the  exception 
stated  above,  these  men  remained  with  the  party 
continuously  until  the  completion  of  the  work, 
when  they  were  ordered  to  report  to  the  Com- 
mis>iion  at  Washington  and  there  discharged. 
Mr.  O'Reardon  has  continued  as  mv  assistant  in 
the  office. 


Drilling  Operations. — Drilling  operations 
were  begun  at  Ochoa  early  in  January,  1898. 
Work  was  continued  at  this  point  and  on  the 
San  Francisco  embankment  until  early  in  March. 
The  party  was  then  divided;  one  party,  consist- 
ing of  Messrs.  Tierney,  Bernstein  and  Archam- 
bault, being  sent  to  the  west  side,  and  another, 
consisting  of  Messrs.  Spence,  Herbert  and 
Fischer,  beginning  work  on  the  upper  San  Juan 
river.  The  work  on  the  west  side  was  done  under 
my  immediate  direction,  while  Mr.  O'Reardon 
was  left  with  the  river  party  to  make  locations 
and  to  keep  the  records.  He  was  later  placed 
in  charge  of  the  party.  The  work  on  the  west 
side  was  completed  on  July  13,  and  the  party 
was  moved  back  to  the  east  side  and  began  work 
on  the  various  proposed  dam  sites  on  the  river. 
This  work  was  completed  about  ibjd  middle  of 
September,  and  the  work  by  the  river  party  was 
completed  on  the  23d  of  that  month.  Messrs. 
O'Reardon,  Spence  and  Archambault  were  then 
ordered  to  report  at  headquarters  in  Washington, 
and  a  single  party  was  started  at  work  on  the 
Eastern  Divide.  This  consisted  of  Mr.  Tier- 
ney, in  charge,  with  Messrs.  Bernstein,  Fischer, 
Herbert,  Seymour,  Smith  and  Miller.  The 
Eastern  Divide  work  was  completed  early  in 
November,  and  the  boring  outfit  was  stored  in 
Greytown,  and  all  members  of  the  party  re- 
turned to  Washington  except  Bernstein  and 
Seymour,  who  remained  at  Greytown  subject 
to  your  orders.     Early  in  December  it  was  de- 


94 


NICARAGUA  CANAL  COMMISSION 


cided  to  have  some  additional  work  done  on  the 
site  of  the  proposed  dam  at  Boca  San  Carlos, 
and  this  was  placed  in  charge  of  Mr.  Bernstein. 
He  began  work  early  in  January,  1899,  &nd 
completed  it  in  about  a  month. 

General  Geologic  Woek. — From  the  date 
of  receiving  your  letter  of  instructions  until 
my  return  to  Washington  at  the  end  of  Septem- 
ber, the  greater  part  of  my  time  was  devoted 
to  the  personal  direction  of  the  boring  parties. 
In  connection  with  this,  I  was  able  to  make  a 
somewhat  detailed  examination  of  the  surface 
geology  in  the  region  adjacent  to  the  canal 
route.  It  was  found,  however,  that  from  the 
nature  of  the  country,  and  especially  by  reason 
of  the  luxuriant  vegetation  and  the  depth  of 
rock  decay,  conclusions  derived  from  a  study  of 
the  natural  rock  outcrops  were  unsatisfactory, 
and  most  of  the  exact  data  obtained  was  by 
means  of  the  drilling  operations.  Observations 
were  made  on  the  physiography  of  the  region, 
which  not  onlv  have  considerable  scientific  in- 
terest,  but  are  believed  to  have  a  very  direct 
bearing  upon  the  practical  engineering  prob- 
lems connected  with  the  construction  of  the 
canal.  Some  examination  was  made  of  regions 
at  some  distance  from  the  canal  route,  though 
less  of  this  was  done  than  desired,  and  a  much 
further  exploration  of  this  portion  of  the  isth- 
mian region  might  be  made  with  distinct  advan- 
tage to  the  solution  of  problems  connected  with 
the  canal.  In  connection  with  iir.  Davis  a 
nearly  complete  circuit  of  the  lake  was  made  and 
the  geology  of  its  shores  examined.  The  region 
to  the  northwest  of  Lakes  Nicaragua  and  Man- 
agua was  studied  with  special  reference  to  the 


origin  of  those  lakes,  and  also  with  reference 
to  the  practicability  of  constructing  a  waste- 
way  from  the  lake  westward  to  the  Pacific. 

Scope  of  the  Report. — The  accompanying 
report  consists  of  two  parts.  The  first  is  in  the 
main  theoretical.  It  embraces  some  account  of 
the  topography  of  the  region,  the  climatic  con- 
ditions in  their  relation  to  physiographic  pro- 
cesses now  going  on,  a  description  of  the  vari- 
ous rock  formations,  a  consideration  of  the  seis- 
mic phenomena  of  the  region,  and  the  proba- 
bility of  the  occurrence  of  earthquakes  and 
finally  a  brief  outline  of  the  recent  geologic  his- 
tory of  the  region.  The  second  part  is  a  more  di- 
rect practical  application  of  the  facts  of  geology 
to  the  engineering  problems.  In  this  the  classi- 
fication of  materials  is  discussed  and  a  somewhat 
fuller  description  of  the  rock  formations  and 
their  mode  of  weathering  is  given,  and  second, 
the  various  localities  at  which  it  is  intended  to 
erect  structures,  such  as  dams,  weirs  and  locks, 
are  described;  also  the  various  lines  in  excavation 
and  the  various  embankment  lines.  Xot  the 
least  important  feature  of  this  portion  of  the 
report  is  the  discrimination  between  that  which 
is  actually  known  concerning  the  geological  con- 
ditions  prevailing  at  various  points   and   that 

which  is  inferred.     This  naturallv  leads  to  the 

t' 

final  section  of  the  report,  in  which  the  addi- 
tional work  needed  before  final  plans  can  be 
made,  is  pointed  out  in  some  detail. 

Very  respectfully  submitted, 

C.  WiLLARD  Hayes, 

Geologist,  U.  S.  G.  S. 

April  12,  1899. 


APPENDIX  II.— GEOLOGIC  REPORT 


95 


PART  I 

PHYSIOGRAPHY  AND  GEOLOGY  OF  THE 

CANAL  REGION 


TOPOGRAPHY. 


The  Nicaraguan  Depression. — The  region 
whose  topography  has  a  direct  bearing  upon  the 
problem  of  the  Nicaragua  Canal  embraces  north- 
ern Costa  Kiea  and  southern  Nicaragua.  It  is 
sharply  limited  on  the  south  by  the  high  vol- 
canic range  of  Costa  Rica  which  rears  its  mas- 
sive form  dia<ronallv  across  the  isthmus.  It  is 
less  definitely  limited  on  the  north  by  the  in- 
creasing height  of  a  deeply  dissected  plateau- 
which  merges  with  the  high  mountains  of  north- 
ern Nicaragua.  Between  these  limits  lies  a 
broad  irregular  depression  which  extends  very 
nearly  across  the  isthmus  in  a  diagonal  direction 
parallel  with  the  Costa  Rican  range.  This  de- 
pression is  now  occupied  chiefly  by  Atlantic 
drainage,  the  Continental  Divide  lying  within  a 
short  distance  of  the  Pacific.  It  contains  the 
basins  of  Lakes  Nicaragua  and  ^Managua  and 
their  outlet,  the  San  Juan  river,  the  latter  occu- 
pying a  position  toward  its  northern  margin.  It 
is  important  to  note  at  the  outset  that  the  de- 
pression is  not  a  simple  river  valley.  The  por- 
tion with  which  we  are  chieflv  concerned,  that 
lying  between  the  lake  and  the  Caribbean,  em- 
braces two  distinct  drainage  basins  whose 
streams  formerly  flowed  in  opposite  directions, 
although  by  a  geologically  recent  reversal  of 
the  drainage  they  now  have  a  single  outlet  to 
the  sea. 


Classification  of  TopooRArnic  Features. — 
When  examined  in  detail  the  surface  of  the 
Nicaraguan  depression  presents  considerable 
relief  and  its  topographic  features  naturally 
group  themselves  in  three  classes. 

Extending  from  the  base  of  the  Costa  Rican 
volcanoes  northward  to  the  San  Juan  river  and 
beyond  are  many  hills  whose  summits  reach  to 
a  tolerablv  uniform  elevation  on  north  and  south 
lines  but  increase  in  height  from  either  side  of 
the  isthmus  toward  its  axis.  In  the  vicinity  of 
the  larger  streams  as  the  San  Juan  and  San 
Carlos  these  hills  have  steep  slopes  and  rounded 
summits.  Farther  back  from  the  streams  the 
valleys  which  separate  them  are  narrower  and 
there  are  considerable  areas  of  level  or  undu- 
lating surface  at  an  altitude  corresponding  with 
the  hill  tops  near  the  streams.  It  is  evident  that 
if  the  valleys  were  filled  even  with  the  summits 
of  these  hills  there  would  be  formed  a  broad 
undulating  plain,  sloping  gradually  up  from 
either  side  toward  the  axis  of  the  isthmus.  It 
is  entirely  probable  that  such  a  plain  once  ex- 
isted and  that  it  has  been  converted  into  a  series 
of  even-topped  hills  and  ridges  by  the  cutting 
of  stream  channels  below  its  surface.  The  man- 
ner in  which  this  plain  was  originally  formed 
is  manifestly  by  the  long-continued  action  of 
streams  when  the  land  stood  considerably  lower 


96 


NICARAGUA  CANAL  COMMISSION 


than  now,  that  is,  by  the  process  of  stream  degra- 
dation or  base  leveling.  It  was,  therefore,  a 
gradational  and  not  a  constructional  plain.  If 
it  were  reconstructed  by  the  filling  of  the  stream 
valleys  its  present  altitude  would  vary  between 
100  and  200  feet. 

As  indicated  above,  numerous  valleys  now  in- 
tersect the  surface  of  this  old  plain.  They  vary 
with  the  size  of  the  streams  except  in  the  case  of 
the  San  Juan.  The  reasons  for  this  exception 
will  be  pointed  out  later.  They  are  broadest 
near  the  large  streams  where  the  old  plain  is 
nearly  or  quite  destroyed  and  grow  narrower 
with  increasing  distance  from  the  main  drainage 
lines.  The  smaller  streams  generally  head  in 
narrow  gorges,  but  in  some  cases  they  have  not 
completely  dissected  the  old  plain,  flowing  upon 
its  surface  in  shallow  vallevs  which  lower  down 
give  way  to  narrow  gorges  and  these  in  turn  to 
the  rather  ^vide  alluvial  valleys  near  the  trunk 
stream.  The  greater  part  of  the  erosion  which 
has  dissected  the  surface  of  the  old  plain  was 
accomplished  when  the  latter  stood  much  higher 
than  at  present.  The  valleys  were  then  much 
deeper,  and  none  had  extensive  flood-plains  ex- 
cept perhaps  the  largest  streams  near  the  sea.  A 
recent  change  in  the  altitude  of  the  land  has 
brought  the  valleys  below  sea  level,  changing 
the  rivers,  at  least  in  their  lower  portions,  from 
corrading  to  aggrading  streams.  They  have 
since  silted  up  the  estuaries  thus  formed,  pro- 
ducing the  wide  alluvial  plains  through  which 
they  now  meander. 

Corresponding  in  some  degree  w4th  the  valleys 
incised  within  the  old  plain  are  eminences  ris- 
ing distinctly  above  its  surface.  These  are  re- 
sidual hills  which  bv  reason  of  the  harder  rocks 
of  which  they  are  composed,  or  their  position 
on  the  divides,  far  from  the  main  drainage  lines, 
were  never  reduced  to  the  level  of  the  plain. 


Where  the  plain  was  best  developed,  that  is  near 
the  sea  margin  on  either  side,  these  residual  hills 
are  infrequent  and  inconspicuous.  Thus  to  the 
southward  of  the  San  Juan,  in  the  region  lying 
between  the  Sarapiqui  and  the  San  (.^arlos,  there 
is  an  extensive  area  in  which  the  hills  are  almost 
wholly  remnants  of  the  dissected  plain,  their 
summits  in  general  presenting  little  variation 
in  altitude.  To  the  northward  of  the  San  Juan 
the  residual  hills  occur  with  increasing  fre- 
quency and  greater  altitude,  and  finally  merge 
with  the  mountains  of  northern  Nicaragua. 
It  is  only  where  the  old  plain  is  somewhat  well 
presented  that  the  true  character  of  the  residual 
hills  is  clearly  seen.  At  certain  points  along 
the  San  Juan  they  rise  directly  from  the  river 
valley,  all  remnants  of  the  intermediate  plain 
having  been  destroyed.  The  residual  hills  also 
increase  in  number  and  height  from  either  side 
of  the  isthmus  toward  its  center,  being  most 
abundant  along  a  line  which  crosses  the  San 
Juan  valley  in  the  vicinity  of  Castillo.  If  the 
plain  were  reconstructed  by  the  filling  of  the 
vallevs  it  would  not  be  continuous  but  would 
pass  from  one  side  of  the  isthmus  to  the  other 
through  comparatively  low  gaps  between  the 
residual  hills. 

Summing  up  the  above  statements  very 
briefly,  then,  it  appears  that  we  have  in  this 
region  a  broadly  undulating  plain  formed  by  the 
erosion  of  streams  flowing  to  the  Pacific  and  to 
the  Atlantic  from  low  gaps  at  the  Divide. 
Above  this  plain  are  residual  hills,  most  abundant 
at  the  axis  of  the  isthmus  where  the  Continental 
Divide  was  formerly  located,  but  increasing 
toward  the  north  where  they  merge  with  the 
mountains  of  northern  J^icaragua;  and,  finally, 
there  are  many  valleys  cut  in  the  surface  of  the 
plain  by  the  erosion  of  the  streams  after  the 
region   had  been   lifted   to   a   higher   altitude, 


APPENDIX  II.— GEOLOGIC  REPORT 


97 


The  lower  portions  of  these  valleys  have  sub- 
sequently been  drowned  and  silted  up,  with  the 
formation  of  broad  alluvial  flood-plains. 

With  these  fundamental  eonceptioms  clearly 
in  mind  the  topographic  features  of  the  Nica- 
raguan  depression  may  be  taken  up  and  de- 
scribed more  in  detail.  They  will  be  considered 
in  the  reverse  order,  that  is,  the  youngest  of  the 
topographic  forms  will  be  considered  first  and 
the  successively  older  ones  later. 

Alluvial  Plains. — Since  the  river  valleys  are 
in  general  closely  followed  by  canal  routes  the 
alluvial  flood-plains  become  of  prime  importance 
in  planning  any  canal.  They  should  be  con- 
sidered not  alone  with  reference  to  their  present 
form  and  composition,  but  also,  in  this  region  at 
least,  with  reference  to  their  origin  and  the  topo- 
graphic forms  which  they  cover  and  conceal. 

The  coastal  plain  on  the  Atlantic  side  of  the 
isthmus  increases  from  a  mere  fringe  at  the 
base  of  the  mountains  in  Costa  Eica  northward 
to  a  belt  from  10  to  15  miles  wide  in  the 
vicinity  of  Greytown.  This  portion  of  it  is 
formed  chiefly  from  materials  brought  down  by 
the  rivers  heading  in  the  Costa  Eican  volcanoes; 
it  is,  in  fact,  a  series  of  coalescing  deltas  of 
which  the  largest  is  that  formed  by  the  San 
Juan.  The  sediment  brought  down  to  the  sea 
by  streams  north  of  the  San  Juan  is  very  small 
compared  with  that  brought  down  by  those  to 
the  south.  The  more  rapidly  growing  southern 
deltas  would,  therefore,  be  extended  seaward 
except  for  a  strong  northward  littoral  sand  cur- 
rent set  up  by  the  oblique  direction  at  which  the 
prevailing  winds  strike  the  shore.  The  true  litr 
toral  current  in  this  portion  of  the  Caribbean  is 
to  the  southward,  but  its  capacity  for  transport- 
ing sediment  is  more  than  neutralized  by  the 
active  northward  sand  drift  within  the  zone  of 
surf  action.  This  sand  drift  tends  to  distribute 
7 


the  sediment  evenly  along  the  coast  and  preserve 
gently  curving  coast  lines.  Notwithstanding 
this  tendency  the  San  Juan  delta  has  been  built 
out  a  short  distance  into  the  Caribbean  forming 
a  shallow  embayment  to  the  northward  of  Har- 
bor Head. 

The  level  surface  of  the  delta  plain  is  inter- 
rupted by  numerous  low  rounded  hills  com- 
posed of  residual  clay  derived  from  the  decay 
of  rock  in  situ,  and  differing  decidedly  in  ap- 
pearance and  composition  from  the  surrounding 
alluvium.  These  hills  have  the  form  and  ap- 
pearance of  islands  rising  above  the  level  delta 
plain,  and  it  is  quite  probable  that  they  were  at 
one  time  islands  fringing  the  shore  before  the 
alluvial  deposits  extended  out  to  them  and  con- 
nected them  with  the  mainland. 

The  inner  margin  of  the  delta  plain  is  ex- 
tremely irregular.  The  isolated  hills  increase 
in  number  and  size  and  finally  merge  with  the 
dissected  interior  highland  while  the  delta  plain 
itself  merges  with  the  broad  flood-plains  of  the 
streams. 

The  surface  of  the  delta  plain  in  its  seaward 
portion  is  but  a  few  feet  above  tide  level.  Its 
extreme  outer  margin  is  marked  by  low  ridges 
parallel  with  the  shore,  formed  by  the  sand 
thrown  up  during  exceptional  storms.  From 
the  shore  margin  the  surface  of  the  plain  ascends 
towards  the  interior  at  a  fairly  uniform  rate  of 
about  18  inches  to  the  mile. 

The  surface  of  the  delta  plain  is  also  diver- 
sified by  numerous  small  lakes  and  lagoons. 
These  are  produced  chiefly  in  two  ways:  (1)  by 
the  formation  of  sand  spits  and,  (2)  by  unequal 
sedimentation. 

Sediment  is  delivered  by  the  larger  streams 
slightly  faster  than  it  can  be  distributed  by  the 
littoral  current.  Hence  it  tends  to  build  out  a 
delta,  but  this  is  deflected  in  the  direction  of 


98 


NICARAGUA   CANAL  COMMISSION 


the  current  and  forms  a  curved  sand  spit  which 
for  a  time  makes  a  well-sheltered  harbor.  As 
the  sand  spit  continues  to  pn'ow,  however,  its 
point  eventually  joins  the  mainland  and  the 
harbor  is  converted  into  a  chased  lagoon.  This 
complete  cycle  of  changes  has  taken  place  at 
Greytown  during  the  last  century  and  a  half. 
The  cycle  has  also  been  repeated  at  the  same 
point  several  times  ])revi()us  to  the  last,  giving 
rise  to  the  Shei)ard,  Sucio,  Barca  and  Ibo  bgoons 
which  occur  back  of  and  parallel  with  the  one 
last  formed.     (See  Plate  I.) 

Agua  Dulce  and  Parada  lagoons  doubtless  owe 
their  origin  to  the  same  process.  The  mouth  of 
the  stream  emptying  into  the  lagoon  is  for  a 
time  candied  forward  in  the  direction  of  the 
littoral  current,  but  when  this  has  gone  to  a 
certain  point,  the  river  seeks  a  more  <lirect 
course  to  the  sea,  breaking  through  the  barrier 
as  the  Colorado  has  evidently  done  verv  recently 
while  the  deserted  outlet  is  quickly  obliterated. 
The  lagoons  are  thus  arranged  in  parallel  series 
on  that  side  of  the  stream  toward  which  the  lit- 
toral current  sets.  The  position  of  the  Agua 
Dulce  and  Parada  lagoons  with  reference  to  the 
Colorado  river  therefore  proves  conclusively 
that  the  northward  sand  current  observed  oppo- 
site Greytown  originates  to  the  southward,  at 
least  beyond  the  Colorado. 

The  second  method  by  which  lagoons  are 
formed  on  the  delta  plain  is  by  unequal  sedi- 
mentation. As  the  coast  was  built  outward  bv 
additions  to  its  outer  margin  it  advanced  past 
numerous  islands  which  had  fringed  the  shore. 
These  in  some  cases  prevented  the  uniform 
deposition  of  sediment  by  interrupting  the  lit- 
toral sand  stream  and  the  areas  in  which  little 
or  no  deposition  took  pjace  subsequently  formed 
lakes.  Perhaps  the  best  example  of  a  lake 
formed  in  this  manner  is  Lake  Silico.     This  oc- 


cupies what  was  evidently  at  one  time  a  bay 
sheltered  bv  the  Silico  hills  which  then  formed 
a  group  of  islands.  As  the  delta  plain  was 
built  outi?onnecting  these  islands  with  the  main- 
land the  sheltered  bav  was  not  filled  bv  sediment, 
but  its  opening  was  cut  oil  and  a  lake  thus 
formed. 

Another  class  of  lakes  or  lagoons  formed  by 
unequal  sedimentation  is  found  about  the  mar- 
gins of  the  delta  plain  and  of  the  river  flood- 
plains.  The  rivers  which  head  upon  the  Costa 
Pican  volcanoes  carrv  a  much  more  abundant 
sup])ly  of  sediment  than  the  smaller  streams 
which  flow  from  a  region  compos(»d  of  compact 
residual  clays  protected  by  a  heavy  mantle  of 
vegetation.  Hence  the  flood-plains  of  the  San 
Juan,  below  the  confluence  with  the  San  Carlos, 
are  built  up  more  rapidly  than  those  of  its  tribu- 
taries. The  latter  are  therefore  dammed  and 
form  lagoons  in  their  upper  basins.  The 
Florida  lagoon  is  a  typical  example  of  this  class. 
Since  they  occupy  drowned  stream  basins  in  a 
region  wdiich  originally  had  considerable  relief, 
their  outlines  are  very  irregular,  the  water  back- 
ing up  all  the  minor  tributari(»s  of  the  basin.  In 
some  cases,  as  in  the  Taud)orcito  region,  the 
water  surface  has  been  raised  above  the  gaps  be- 
tween neighboring  streams  and  their  basins  are 
now  confluent  while  the  residual  land  rising 
above  the  lagoon  level  forms  isolated  groups  of 
hills. 

The  lagoons  of  the  delta  plain  formed  in  these 
various  ways  are  at  first  open  lakes,  but  they 
gradually  become  choked  by  vegetation  and  filled 
wuth  fine  silt  so  that  thev  are  converted  into 
grassy  marshes  and  finally  when  the  silt  be- 
comes sufficiently  consolidated  to  form  a  stable 
support  the  forest  trees  encroach  upon  the 
marsh  and  all  trace  of  the  lagoon  is  lost.  Num- 
erous examples  occur  in  the  delta  plains,  illus- 


NICARAGUA  CANAL  COMMI88IDN. 

APPENDIX  2, 

PLATE  1. 

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MAP  OF  THE  SAN  JUAN  DELTA. 


APPENDIX  II.— GEOLOGIC  REPORT 


99 


trntin«r  everr  step  in  the  process:  first,  the  open 
lagoon,  then  the  floating  grass-mat,  then  the 
Silieo  swamp,  and  finally  the  heavy  forest. 

A>  alrea<lv  indicated,  the  delta-plain  at  its 
inner  margin  merges  with  the  broad  flood-plain 
of  the  San  Jnan  river  and  any  line  separating 
the  two  wonld  be  pnrely  arbitrary.  For  con- 
venience, however,  the  head  of  the  delta  may  be 
placed  at  the  point  where  the  first  distributary, 
the  San  Jnanillo,  leaves  the  main  stream. 

Most  flood-plains  are  formed  by  the  lateral 
cutting  of  streams  as  they  swing  from  side  to 
side  in  their  valleys.  A  plain  thus  cut  in  the 
nnderlving  rocks  is  nsnallv  covered  with  a  thin 
sheet  of  alluvial  material.  The  flood-plains  of 
this  region,  however,  belong  to  a  totally  dif- 
ferent class.  They  include*  no  level  plains  cut 
in  the  underlying  rock  or  residual  material  which 
covers  the  rock.  On  the  other  hand,  the  allu- 
vium has  very  considerable  depth,  and  instead  of 
forming  a  layer  of  uniform  thickness,  fills  a 
series  of  old  stream  channels.  It  is  evident  that 
these  channels  were  formed  when  the  land  stood 
higher  than  now,  for  manv  of  them  extend 
below  sea  level.  There  is  thus  an  old  land  sur- 
face concealed  beneath  the  alluvial  deposits,  and 
a  consideration  of  its  topography  becomes  a 
matter  of  prime  importance  to  the  engineer. 
This  buried  topography  will  be  considered  more 
fully  in  connection  with  the  unburied  portion  of 
the  same  surface,  that  is,  the  surface  of  the  hills 
rising  above  the  margins  of  the  alluvial  plains. 

Extensive  flood-plains  extend  up  the  San  Juan 
river  to  the  mouth  of  the  San  Carlos;  above  this 
to  the  head  of  the  Toro  rapids  the  river  flows 
in  a  comparatively  narrow  gorge  and  its  flood- 
plains  are  narrow  and  inconspicuous.  From 
the  Boca  San  Carlos  downward  to  the  head  of 
the  delta,  flood-plains  are  always  present  on  one 
or  both  sides  of  the  river,  though  they  are  most 


extensively  developed  on  the  south  side.  The 
surface  is  slightly  higher  near  the  river,  forming 
the  natural  levee  which  characterizes  most  flood- 
plains.  The  outer  margins  are  depressed  and 
occupied  by  swamps  or  lagoons.  The  surface 
of  the  flood-plains  in  the  vicinity  of  the  Boca 
San  Carlos  varies  from  15  to  20  feet  above  the 
river  at  ordinary  low  stages.  As  the  plains  be- 
come more  extensive  downstream,  their  surface 
is  slightly  less  elevated,  since  the  floods  which 
deposit  the  alluvium,  having  opportunity  to 
spread  over  a  much  larger  area,  do  not  rise  so 
high. 

The  slope  of  the  flood-plains  from  the  Boca 
San  Carlos  to  the  head  of  the  delta  is  about  12 
inches  per  mile.  This  slope  is  dependent  upon 
the  volume  of  the  river  and  the  character  and 
quantity  of  the  sediment  wdiich  it  carries.  It 
is  therefore  nuich  steeper  below  the  mouth  of 
the  San  Carlos  than  above,  for  it  is  from  this 
stream  that  the  greater  part  of  the  coarse  sedi- 
ment in  the  lower  river  is  derived,  but  it  is  only 
about  two-thirds  as  great  as  the  slope  of  the 
delta  plain. 

As  stated  above,  the  flood-plains  are  incon- 
spicuous from  the  Boca  San  Carlos  to  the  head 
of  the  Toro  rapids.  The  river  flows  in  a  compara- 
tively nari'ow  gorge  and  is  generally  bordered 
by  rather  steep  hills  which  approach  nearly 
to  the  river  channel.  At  the  head  of  the  Toro 
rapids,  however,  the  valley  widens,  and  from 
this  point  to  the  lake  the  river  is  everywhere 
bordered  on  one  or  both  sides  bv  extensive  flood- 
plains.  Although  their  general  relations  to  the 
river  are  similar  to  those  bordering  its  lower 
course  they  yet  differ  in  some  important  par- 
ticulars. They  liave  been  formed  bv  sediment 
borne,  not  bv  the  river  itself,  but  bv  tributaries 
coming  into  the  valley  on  either  side.  They 
thus  have  the  form  of  coalescing  deltas.     The 


100 


NICARAGUA  CANAL  COMMISSION 


natural  levee  which  is  a  conspicuous  feature  in 
the  flood-plains  of  the  lower  river  is  absent,  and 
the  plains  generally  show  a  gradual  descent  from 
their  outer  margins  toward  the  river.  Hence 
there  are  no  lagoons  upon  the  tributaries  such 
as  are  found  on  the  tributaries  of  the  lower  river, 
and  the  flood-plain  becomes  gradually  firmer 
and  more  heavily  wopded  with  increasing  dis- 
tance from  the  river.  From  the  mode  of  forma- 
tion of  these  plains  it  is  manifest  that  the  river 
is  in  a  stable  position  and  does  not  show  that 
tendency  to  seek  a  new  channel  which  is  char- 
acteristic of  delta  streams. 

Most  of  the  streams  entering  Lake  Nica- 
ragua on  its  northeastern  side  at  one  time  en- 
tered the  heads  of  estuaries.  These  estuaries 
have  been  almost  entirely  filled  mth  alluvial 
deposits,  and  in  some  cases  somewhat  extensive 
deltas  have  been  built  out  into  the  lake.  The 
absence  of  a  surf  in  this  portion  of  the  lake,  ex- 
cept on  rare  occasions,  owing  to  the  direction  of 
prevailing  winds,  permits  the  building  of  deltas 
which  carry  the  distributaries  of  the  streams 
a  considerable  distance  out  from  the  general 
shore  line.  The  most  extensive  alluvial  deposits 
about  the  lake  are  at  its  southern  end.  This 
portion  of  the  lake  basin  appears  to  have  been 
originally  rather  shallow  and  the  sediment 
brought  in  by  streams  from  the  south,  notably 
by  the  Rio  Frio,  has  considerably  contracted 
its  area.  The  newly-added  land  forms  about 
the  margin  of  the  lake  an  extensive  swamp 
through  which  the  streams  meander  in  a  network 
of  interlacing  distributaries,  all  more  or  less 
obstructed  by  vegetation.  The  land  becomes 
gradually  firmer  at  increasing  distances  from 
the  lake  and  finally  passes  into  an  ordinary  allu- 
vial flood-plain.  Streams  entering  the  lake  from 
the  southwest  in  general  flow  in  channels  which 
were  at  one  time  excavated  to  a  very  inconsid- 


erable depth  below  the  present  surface  of  the 
plain  through  which  they  flowed.  This  plain,  it 
may  be  remarked  in  passing,  is  not  alluvial,  but 
is  a  plain  of  degradation.  Hence  these  streams 
are  bordered  by  very  inconsiderable  alluvial 
plains  and  that  only  near  the  lake.  The  streams 
entering  the  Pacific  from  this  portion  of  the 
isthmus  are  all  short  and  consequently  small, 
since  the  Continental  Divide  is  near  the  west 
coast.  They  occupy  valleys  which  have  been 
cut  to  a  much  greater  depth  than  they  have  at 
present,  and  these  old  valleys  have  been  recently 
drowned  and  more  or  less  perfectly  filled  with 
alluvial  deposits.  Where  the  filling  is  not  quite 
complete  an  estuary  occupies  the  old  river  valley 
and  forms  a  harbor  as  in  the  case  at  San  Juan  del 
Sur.  Where  the  filling  is  complete,  as  in  the  val- 
ley of  the  Eio  Grande,  the  headlands  which  mark 
the  margins  of  the  former  deep  valley  are  con- 
nected by  a  curved  beach  which  does  not  indent 
the  coast  to  any  appreciable  extent.  The  depth 
of  the  alluvium  in  the  Rio  Grande  vallev  varies 
from  about  40  feet  at  the  head  of  the  flood-plain 
to  something  over  100  feet  at  the  coast.  The 
stream  which  has  filled  this  vallev  carries  at 
certain  seasons  an  abundant  supply  of  sediment, 
so  that  the  seaward  slope  of  the  flood-plain  is 
rather  steep,  a  little  over  ten  feet  to  the  mile. 
The  conditions  in  this  region  which  determine 
the  rate  of  erosion  are  much  more  favorable  to 
rapid  degradation  of  the  surface  than  in  the 
region  of  much  greater  rainfall  to  the  east,  where 
the  rain  is  distributed  somewhat  equally  through- 
out the  year.  The  streams  are  alternately 
shrunken  to  mere  rivulets  and  swelled  to  tor- 
rents and  the  resulting  flood-plain  has  somewhat 
the  character  of  an  alluvial  cone. 

The  Dissected  Peneplain, — The  group  of 
topographic  forms  to  be  described  next  in  order 
after  the  alluvial  plains,  consists  of  a  more  or 


APPENDIX  II.— GEOLOGIC   REPORT 


101 


less  completely  dissected  plain  or  peneplain  of 
degradation.  In  order  to  understand  the  present 
topography  it  is  necessary  to  consider  the  orig- 
inal form  of  this  plain  and  the  manner  in  which 
it  was  developed.  The  conditions  which  pre- 
vailed prior  to  its  formation  cannot  be  definitely 
determined,  but  may  be  inferred  in  a  general 
way.  There  was  probably  a  somewhat  elevated 
plateau  growing  broader  and  higher  both  to  the 
northward  and  the  southward  from  a  somewhat 
constricted  region  now  occupied  by  the  Xica- 
raguan  depression.  The  Continental  Divide  at 
that  time  probably  occupied  a  position  near  the 
central  part  of  the  isthmus,  crossing  the  present 
San  Juan  vallev  in  the  vicinitv  of  the  Castillo 
rapids,  and  streams  heading  upon  this  Divide 
flowed  to  the  seas  on  either  side.  Another  im- 
portant difference  was  in  the  form  and  position 
of  the  Pacific  coast  line.  The  differences  in 
the  geography  of  the  region,  so  far  as  they  can 
be  inferred,  are  represented  on  the  accompany- 
ing sketch  map,  Plate  11.  It  will  be  noted  that 
Lake  Nicaragua  did  not  then  exist.  Its  present 
basin  was  occupied  in  part  by  a  bay  indenting  the 
coast  line  and  in  part  by  the  basins  of  rivers  trib- 
utary to  this  bay.  The  region  occupied  by  the 
volcanic  peaks  of  the  Xicaraguan  range  and  the 
volcanic  plateau  west  of  the  lake  was  then  oc- 
cupied by  the  sea.  A  cape  projecting  north- 
ward between  the  sea  and  the  bay  was  composed 
of  low  hills  now  forming  the  Continental  Di- 
vide southwest  of  the  lake. 

In  still  other  respects  the  drainage  of  the 
region  during  the  formation  of  this  peneplain 
differed  from  the  present.  The  San  Juan  river 
receives  onlv  small  tributaries  from  the  north 
while  it  receives  both  small  and  large  from  the 
south.  The  large  tributaries  include  the  Frio, 
Poco  Sol,  San  Carlos  and  Sarapiqui.  These  all 
head  upon  the  slopes  of  the  Costa  Rican  volcanic 


range  which  forms  the  southern  margin  of  the 
Nicaraguan  depression.  The  upper  portions  of 
these  streams  are  normal  to  the  mountain  range, 
the  axes  of  their  valleys  being  at  right  angles 
to  the  axis  of  the  range  and  also  to  the  general 
course  of  the  San  Juan.  Midway  of  their 
courses,  however,  there  is  an  abrupt  change  in 
direction.  The  Frio  and  Poco  Sol  bend  west- 
ward while  the  San  Carlos  and  Sarapiqui  bend 
eastward,  the  axes  of  the  lower  valleys  in  every 
case  making  a  rather  acute  angle  with  the  course 
of  the  San  Juan.  It  seems  probable  that  when 
the  peneplain  was  being  developed  in  this  region 
the  two  rivers  whose  basins  now  form  that  of 
the  San  Juan  occupied  the  axes  of  those  basins 
receiving  tributaries  of  equal  length  from  either 
side.  The  volcanic  eruptions  to  the  south, 
however,  obliterated  the  former  drainage  of  that 
region,  and  the  consequent  streams  developed  on 
the  flanks  of  the  newly-formed  moimtains  were 
turned  northward,  discharging  into  the  head^  of 
the  pre-existing  small  tributaries.  It  thus  ap- 
pears that  the  four  above-named  southern  tribu- 
taries of  the  San  Juan  have  composite  courses. 
Their  upper  courses,  normal  to  the  trunk  stream, 
are  consequent)  upon  the  constructional  slope 
of  the  recent  volcanic  range,  their  lower  courses 
making  acute  angles  with  the  trunk  stream  are 
inherited  from  the  normally-developed,  small 
tributaries  of  two  streams  flowing  east  and  west. 
The  rapidity  with  which  the  streams  heading 
upon  the  Continental  Divide  reduced  their  val- 
leys to  base  level  depended  chiefly  upon  the 
character  of  the  rocks  which  they  encountered, 
while  the  rate  at  which  the  Divide  was  lowered 
by  the  action  of  opposing  streams  depended  upon 
the  character  of  the  rocks  and  the  distance  of 
the  Divide  from  the  coast,  or  the  width  of  the 
isthmus.  The  region  to  the  northward  is  prob- 
ably occupied  by  older  and  more  resistant  rocks, 


102 


NICARAGUA  CANAL  COMMISSION 


iiichuling  gneisses,  schists  and  quartzites.  Of 
tliat  to  the  south  \crj  little  is  known  since  its 
topography  has  been  entirely  changed  and  its 
older  rock  formations  concealed  bv  the  recent 
eruptions  of  its  A'olcanoes.  From  this  com- 
bination of  circnmstances  it  followed  that  the 
surface  was  most  completely  degraded  and  the 
Divide  most  rapidly  lowered  along  a  belt  ex- 
tending diagonally  across  the  isthmns  and  now 
forming  the  great  Xicaraguan  depression.  A 
broad  river  basin  was  developed- on  the  east  side 
of  the  Divide,  occupying  the  present  position 
of  the  lowcT  San  Juan  basin.  The  land  be- 
tween its  various  southern  tributaries  was  re- 
duced to  low  relief.  Its  nortluTU  tributaries 
were  separated  by  somewhat  higher  hills,  prob- 
al)ly  the  result  chieflv  of  the  greater  oriijinal 
elevation  of  this  portion  of  the  region.  Another 
river  system  developed  a  similar  basin  with  its 
outlet  to  the  Avest.  The  several  upper  tribu- 
taries of  each  of  these  two  river  svstems  headed 
upon  the  Continental  Divide  in  low  ga])s  against 
the  tributaries  of  the  other  system.  The  basin 
of  the  western  svsteni  was  somewhat  larger 
than  the  one  on  the  east  of  the  Divide.  Its  lower 
portion  Avas  separated  from  the  Pacific  by  a  range 
of  hills  Avhich  continued  nortlnvestward,  form- 
ing the  cape  between  the  then  existing  bay  and 
the  ocean.  The  southern  portion  of  the  present 
basin  of  Lake  Nicaragua  Avas  occupied  by  this 
river  system,  and  extensive  plains  Avere  devel- 
oped on  either  side  of  the  axis  extending  up  the 
tributaries  as  broad  valleys  well  back  into  the 
surrounding  liills. 

The  foregoing  brief  account  of  the  original 
extent  of  this  peneplain  and  the  manner  in 
which  it  Avas  formi^d  is  an  essential  preliminary 
to  an  understanding  of  the  present  topography  of 
the  region.  At  the  conclusion  of  the  long 
period  of  degradation,  during  which  the  Xica- 


raguan  dei>res>ion  was  reduced  to  a  region  of 
low  relief,  the  laud  was  sIoavIa-  elevated  until  it 
stood  some  hundred  feet  higher  than  before  and 
perhaps  tAvo  hundred  feet  higher  than  now. 
The  elevation  stimulated  the  streams  to  rencAved 
activity,  and  they  began  trenching  the  A'alleys 
AA'hich  they  had  previously  formed.  The  ero- 
sion was  at  first  most  active  near  the  coast  and 
worked  backward  toward  the  interior  most  rap- 
idly along  the  largest  streams.  The  portions  of 
the  peneplain  most  completely  dissected  Avere, 
therefore,  its  ontor  margins.  Here  the  surface 
was  almost  entirelv  reduced  to  the  lower  base- 
level  and  ouIa-  a  few  rounded  hills  on  the  divides 
retained  any  trace  of  the  former  plain.  The  first 
of  these  remnants  s(»en  on  ascending  the  San 
Juan  are  in  the  vicinitv  of  the  delta  head  Avhere 

« 

low  hills  approach  the  river  on  the  north  side. 
This  region,  however,  has  been  so  deeply  dis- 
sected that  the  hilltops  scarcely  suggest  the  ex- 
istence of  a  former  plain.  Other  hills  of  sim- 
ilar character  occur  along  the  river,  chiefiy  on 
the  north  side,  although  the  most  prominent  hills 
Avhich  come  down  to  the  river  do  not  belong  to 
the  group  now  being  described  but  to  the  residual 
hills  Avhich  rose  above  the  surface  of  the  old 
plain  at  the  time  of  its  most  perfect  development. 
The  remnants  of  the  dissected  plain  increase  in 
number  and  in  the  regularity  of  their  summits 
until  in  the  vicinitv  of  Ochoa  their  uniformitv 
is  such  that  the  position  of'  the  old  peneplain 
(»an  be  accurately  determined.  The  dense  troi> 
ical  forests  mask  the  minor  topographic  features 
so  that  the  uniformitv  in  the  summits  of  the 
hills  is  not  at  once  apparent.  The  detailed 
contour  maps,  however,  of  those  portions  of 
the  rcgion  Avhich  have  been  actually  surveyed 
exhibit  the  uniformity  in  a  striking  manner. 
The  present  elevation  of  the  hilltops  in  this 
region  is  about  150  fe(»t  above  sea  level,  and  the 


NICARAGUA  CANAL  COMMISSION. 


TerTiary  baselevefiog  period ^  — 

f^acific   coast  line   at  ttie  end  oftHe 

poSt-lerTiary  baseleveling  period 

Pi'esetnt    conTrn«nTal  divide  **♦»  +  »♦♦ 

Former   corftmentsl    divide  »-**■»*-* 

Recent"    volcanoes  O  OO 


MAP  SHOWING  CHANGE 


APPENDIX  2,  PLATE  II. 


ST  LINES  AND  DIVIDES. 


APPENDIX  II.— GEOLOGIC  REPORT 


103 


uniformity  of  tlieir  summits  is  shown  in  the 
sections  of  the  San  Carlos  embankment  line, 
Fig.  2,  Plate  III.  To  the  south  of  the  river 
the  old  plain  was  very  extensively  developed,  and 
while  it  has  suffered  much  subsequent  dissection, 
there  is  a  large  area  in  which  its  former  position 
can  be  readily  determined  by  th(»  summits  of 
the  present  hills.  To  the  north  of  the  river  it 
was  less  extensive,  forniinsi:  onlv  broad  vallevs 
between  the  residual  hills  which  occupied  the 
divides.  Although  not  so  extensively  devel- 
oped here  as  south  of  the  river,  the  plain  has 
been  somewhat  better  preserved  and  many 
streams  are  found  which  have  not  vet  lowered 
their  valleys  appreciably  below  the  old  surface. 
Heading  upon  the  steep  residual  hills  their  up- 
per courses  are  in  sharply  cut  V-shaped  valleys. 
Emerging  from  these  they  flow  in  shallow  val- 
leys across  the  remnant  of  the  old  plain,  tlieir 
channels  meandering  and  obstructed  by  swamps. 
Farther  down  they  enter  nari'ow  gorges  which 
they  have  cut  and  are  still  deepening  in  the  old 
peneplain.  Still  farther  down  they  are  bor- 
dered by  alhwial  plains  where  the  valleys  which 
they  cut  in  the  old  plain  have  been  depressed 
below  base  level  and  so  silted  up. 

These  features  are  admirablv  shown  on  the 
Machado  and  other  tributaries  of  the  San  Juan 
in  the  vicinity  of  Ochoa.  They  may  perhaps 
be  made  clearer  by  reference  to  the  somewhat 
idealized  sketch  and  section  forming  Fig.  1, 
Plate  III.  The  surface  of  the  i>eneplain  is  in- 
dicated bv  the  even  summits  of  the  hills  to  the 
right.  Residual  hills  are  represented  to  the  left, 
rising  abruptly  and  distinctly  above  the  surface 
of  the  pene])lain.  The  profile  shows  a  trans- 
verse section  of  the  San  Juan  valley  and  a  longi- 
tudinal section  of  the  vallev  of  a  tributary 
stream.  The  latter  is  re[)re.sented  as  rising  in 
the  residual   hills  to  the   left   and   flowing  for 


some  distance  in  the  narrow  gorge  a  6.  From 
h  to  c  the  stream  flows  in  a  broad,  shalfcw  valley 
at  about  the  level  of  the  peneplain.  From  c  to 
d  it  is  in  a  narrow  gorge  recently  cut  and  still 
being  actively  deepened  within  the  peneplain. 
It  emerges  from  this  gorge  at  d  and  thence  to 
the  margin  of  the  main  river  valley  at  e  it 
meanders  through  an  alluvial  plain,  the  con- 
tinuation of  the  San  Juan  flood-plain  e  /.  The 
bottom  of  the  vallevs  which  the  tributarv  and 
the  trunk  stream  occupied  before  the  recent  de- 
pression of  the  region  is  represented  in  the  pro- 
file by  the  solid  line  between  the  alluvium  and 
the  underlving  rock.  When  these  vallevs  w^ere 
formed  they  were  considerably  above  sea  level 
and  the  streams  had  a  much  more  rapid  fall  than 
at  present,  but  they  arc^  now  somewhat  below 
sea  level. 

Continuing  westward  from  Ochoa  the  sum- 
mits of  the  hills  become  less  uniform  in  altitude, 
corres])onding  with  the  originally  less  perfect  de- 
velopment of  the  old  peneplain  in  the  vicinity 
of  the  former  Continental  Divide.  Along  the 
upper  portion  of  the  river,  west  of  the  Toro 
rapids,  are  numerous  low,  rounded  hills  merging 
on  either  side  of  the  vallev  with  a  more  con- 
tinuous  upland  and  these  probably  mark  the  po- 
sition of  the  former  peneplain.  It  slopes  gently 
westward  and  probably  passes  beneath  the  waters 
of  Lake  Nicaragua.  The  broad  valleys  bordering 
the  streams  which  enter  the  noi^theastem  side 
of  the  lake  and  the  level  plain  which  forms  the 
western  margin  of  the  lake  basin  probably  con- 
stitute parts  of  this  old  plain,  which  have  here 
almost  entirely  escaped  dissection. 

In  connection  Avith  the  remnants  of  this  old 
peneplain  the  topography  of  the  surface  now 
concealed  by  the  alluvial  deposits  should  be  con- 
sidered. At  the  close  of  the  period  of  high 
level,  during  which. the  plain  was  dissected,  the 


104 


NICARAGUA   CANAL  COMMISSION 


valleys  were  rather  narrow  w^ith  steep  slopes  ex- 
cept near  the  coast.  If  the  subsidence  which  in- 
augurated the  period  of  alluviation  had  occurred 
all  at  once,  tidewater  would  have  extended  up 
the  valley  of  the  San  Juan  beyond  the  Boca 
San  Carlos  and  also  some  distance  up  its  tribu- 
taries. It  is  probable,  however,  that  the  land 
sank  very  slowly  so  that  the  estuaries  were  never 
deep,  but  were  filled  by  alluvium  almost  as  fast 
as  formed.  The  depth  of  these  old  valleys  hav- 
ing been  determined  by  borings  at  various  points 
on  the  trunk  stream  and  some  of  its  tributaries, 
it  is  possible  to  reconstruct  the  former  surface 
and  determine  approximately  the  depth  of  the 
alluvial  filling  in  any  part  of  the  drainage  sys- 
tem. It  is  found  that  the  erosion  of  the  hills 
has  been  inconsiderable  since  the  submergence, 
for  the  slopes  above  the  margin  of  the  flood- 
plains  are  practically  the  same  as  the  old  slope 
beneath  the  alluvial  cover.  The  forms  of  the 
alluvium-filled  vallevs  are  shown  on  the  sections 
representing  portions  of  the  San  Francisco  em- 
bankment line,  Plate  XVIII.  The  valleys  of 
the  lower  San  Juan  and  its  tributaries  have  been 
filled  in  such  a  manner  that  the  present  streams 
follow   very    nearlv    the    same    course    as    the 

streams  which   formed   the  vallevs.     In   some 

t/ 

cases  their  meanders  have  carried  them  to  one 
side  or  the  other  of  the  old  valley  where  they 
are  now  cutting  against  the  bordering  hills  of 
residual  clay. 

While  the  existence  of  this  old  channel  might 
be  inferred  with  certainty  from  a  study  of  the 
present  river  valley,  its  form  and  seaward  gradi- 
ent could  be  determined  only  by  boring.  From 
the  data  obtained  with  the  drill  at  the  various 
dam  sites  and  other  points  on  the  river  between 
Machuca  and  Tambor  Grande,  transverse  and 
longitudinal  sections  have  been  constructed, 
which  show  fairly  well  the  characteristics  of  the 


buried  channel.  Its  gradient  as  shown  on  the 
longitudinal  section.  Fig.  2,  Plate  XV,  is  fairly 
uniform  but  considerably  steeper,  than  the  gra- 
dient of  the  present  river.  The  lower  portion  is 
also  steeper  than  the  upper.  Thus  from  Cas- 
tillo to  Ochoa  the  gradient  of  the  rock  chan- 
nel is  about  3  feet  per  mile,  while  from 
Ochoa  to  Tambor  Grande  it  is  5.8  feet. 
The  minor  irregularities  in  the  channel  are 
doubtless  due  to  differences  in  the  hardness  of 
the  rocks,  but  the  increased  slope  of  the  lower 
portion  of  the  channel  is  probably  due  to  some 
change  in  conditions  during  its  formation,  such 
as  a  slight  uplift  toward  the  end  of  the  gorge- 
cutting  period.  The  form  of  the  buried  chan- 
nel is  shown  on  the  five  transverse  sections  at 
dam  sites  between  Machuca  and  Tambor  Grande, 
Figs.  3  to  7,  Plate  XVII.  In  general  the 
buried  slopes  conform  with  those  above  the  pres- 
ent river,  and  its  flood-plains  and  the  sections  are 
about  what  would  have  been  inferred  from  the 
exposed  slopes. 

The  original  form  of  the  surface  concealed  by 
the  flood-plain  of  the  upper  San  Juan  is  much 
more  difficult  to  make  out.  This  plain  was 
formed  by  deposition  in  quiet  water,  the  river 
valley  being  entirely  drowned.  Hence  the  pres- 
ent channel  was  not  determined  by  the  deepest 
portion  of  the  old  vallev  but  bv  the  relative 
amounts  of  sediment  brought  into  this  portion 
of  the  lake  bv  tributaries  on  either  side.  It  is 
evident  that  the  stream  bearing  the  largest 
amount  of  sediment  is  the  Rio  Frio,  and  the 
delta  of  this  stream  has  pushed  the  outlet  of  the 
lake  northward  away  from  the  deeper  portion 
of  the  old  valley  and  against  the  hills  which 
formed  its  margin.  The  same  thing  is  seen  at 
various  points  between  the  lake  and  the  Toro 
rapids.  At  numerous  points  the  meanders  of 
the  river  carry  it  away  from  the  deeper  portions 


APPENDIX  II.— GEOLOGIC  REPORT 


105 


of  the  old  valley  and  against  the  marginal  hills. 
In  most  eases  these  meanders  are  not  accidental, 
but  are  determined  by  the  entrance  of  a  tribu- 
tary on  the  opposite  side.  It  is  therefore  im- 
possible to  determine  the  position  of  the  stream 
which  formerly  occupied  this  valley,  from  the 
present  position  of  the  San  Juan.  Sufficient 
boring  has  been  done  in  this  portion  of  the  river 
channel,  however,  to  determine  the  fact  that  the 
rock  or  residual  clay  slopes  of  the  hills  which  at 
present  rise  above  the  alluvial  plain  continue 
practically  unchanged  beneath  the  alluvium. 
The  importance  of  this  fact  in  the  location  of 
the  canal  line  is  at  once  apparent.  The  line  in 
general  follows  the  channel  of  the  river,  but  if 
tliis  were  strictly  followed  considerable  rock  ex- 
cavation would  be  necessarv  wherever  the  chan- 
nel  swings  against  one  of  the  marginal  hills.  It 
is  evident,  however,  that  by  shifting  the  line 
away  from  the  hill  the  rock  slope  will  pass  be- 
low the  bottom  of  the  canal  so  that  the  excava- 
tion necessary  to  secure  the  required  depth  will 
be  entirely  in  alluvium. 

The  Residual  Hills. — The  third  group  of  to- 
pographic forms  which  characterizes  the  Nicara- 
guan  depression  embraces  the  elevations  rising 
distinctly  above  the  present  tops  of  the  lower 
hills  and  representing  portions  of  the  surface 
never  reduced  to  the  level  of  the  old  peneplain. 
The  summits  of  these  residual  hills  are  entirely 
different  from  the  dissected  remnants  of  the 
peneplain  above  described.  The  crests  are  al- 
ways sharp  and  serrate  with  no  uniformity  what- 
ever in  their  altitudes.  As  already  stated  these 
residual  hills  increase  in  frequency  and  magni- 
tude toward  the  north,  occupying  the  divides 
between  the  northern  tributaries  of  the  San 
Juan. 

The  hills  of  the  Eastern  Divide  lying  between 
the  basins  of  the  Deseado  and  the  San  Fran- 


cisco form  a  characteristic  group  belonging  to 
this  class.  Their  slopes  are  steep  and  their  sides 
are  furrowed  by  sharp  V-shaped  ravines.  Around 
their  base  are  remnants  of  the  old  plain  above 
which  they  formerly  rose,  now  appearing  as 
rounded  hills  with  uniform  summits.  Long 
spurs  radiate  from  the  central  mass  of  the  East- 
ern Divide  hills  and  reach  the  San  Juan  river 
at  several  points,  forming  the  high  ridges  at 
Sarapiqui,  Tamborcito,  Tambor  Grande  and  San 
Francisco.  Another  prominent  group  of  hills 
belonging  to  this  series  occurs  at  the  junction  of 
the  San  Juan  and  San  Carlos.  These  have  a 
form  similar  to  that  of  the  Eastern  Divide  hills, 
but  the  group  is  somewhat  smaller.  The  upper 
slopes  are  extremely  steep  and  the  sides  are 
deeply  gullied  while  the  summit  as  seen  from 
either  side  presents  a  sharply  serrate  outline. 
The  altitude  of  the  San  Carlos  hills  is  about 
1200  feet.  These  isolated  groups  of  high  hills 
occur  with  increasing  frequency  toward  the  line 
formerly  occupied  by  the  Continental  Divide, 
which  probably  crossed  the  present  valley  of  the 
San  Juan  in  the  vicinitv  of  Castillo.  West  of 
this  line  they  decrease  in  frequency  and  height 
to  the  lake.  Along  the  northeastern  margin  of 
the  lake  the  hills  of  this  class  are  represont-ed  by 
the  high  spurs  occupying  the  divides  between 
the  broad  river  valleys.  On  the  west  side  of 
the  lake  they  are  perhaps  represented  by  the 
ranges  of  hills  which  rise  abruptly  from  the 
Eivas  plain  and  extend  from  its  western  margin 
nearly  or  quite  to  the  Pacific.  Northward 
from  the  San  Juan  valley  these  residual  hills 
increase  gradually  in  height  and  numbers,  form- 
ing the  divides  between  the  lake  and  Caribbean 
drainage  and  the  subordinate  divides  between 
the  streams  of  each  system.  By  their  gradual 
increase  in  this  direction  they  form  the  indefinite 
northern  limit  of  the  great  Nicaraguan  depres- 


106 


NICARAGUA   CANAL  COMMISSION 


sion.  In  northern  Nicaragua  they  attain  con- 
siderable size,  forming  mountains  which  reach 
altitudes  of  five  to  seven  thousand  feet. 

The  AVkstekx  Divide. — As  alreadv  indi- 
cated,  the  great  Kicaraguan  depression  was 
formed  before  Lake  Nicaragua  came  into  exist- 
ence. It  originally  extended  entirely  across  the 
isthmus,  terminating  to  the  westward  at  the  bay 
which  then  indented  the  Pacific  coast,  a  cape 
projecting  to  the  northwestward  between  this 
bay  and  the  ocean.  The  cape  now  forms  the 
southern  part  of  the  narrow  isthmus  lying  to  the 
southwestward  of  Lake  Nicaragua  and  separating 
it  from  the  Pacific.  This  strip  of  land  is  not 
properly,  therefore,  a  part  of  the  Nicaraguan 
depression  and  its  topography  should  be  inde- 
pendently considered. 

Bordering  the  southwestern  shore  of  the  lake 
and  extending  northwestward  nearly  to  Zapatera 
island,  is  a  very  perfectly  base-leveled  surface, 
termed,  for  convenience,  the  Kivas  plain.  It 
varies  in  width  from  five  to  twelve  miles  and  is 
continuous  along  the  lake  margin  except  near 
the  Sapoa  river  where  it  is  interrupted  for  a 
short  distance  by  high  hills  coming  down  to  the 
lake.  Very  little  is  known  concerning  the 
southeastern  extension  of  this  plain,  but  it  is 
probably  nearly  or  quite  continuous  around  the 
end  of  the  lake  with  the  pcne^>lain  of  the  Nica- 
raguan depression  already  described.  Its  north- 
eastern margin  is  the  lak(^  shore,  where  the 
waves  have  cut  a  shallow  terrace  backed  by  a 
cliff  from  ten  to  fortv  feet  in  hei^rht.  A  few 
low  rounded  hills  rise  above  its  even  surface  but 
they  seldom  attain  heights  of  more  than  one 
hundred  feet.  In  the  vicinity  of  Rivas,  where 
it  is  most  thoroughly  known,  the  plain  ascends 
toward  the  southwest  at  the  rate  of  about  eight 
feet  to  the  mile  to  the  base  of  the  hills  which 
occupy  the  greater  part  of  this  strip  and  form 


the  Continental  Divide.  These  hills  rise  abruptly 
from  the  Rivas  plain  to  heights  of  800  to  1200 
feet  above  tide,  and  extend  northward  to  a  ix)int 
opposite  the  island  of  Zapatera  where  they  meet 
the  Jinotepe  plateau  and  the  serrate  residual  out- 
line of  the  former  gives  place  to  the  even  con- 
structional slope  of  the  latter.  A  single  break 
occurs  in  this  continuous  line  of  hills.  This  is 
the  gap  betw^een  the  waters  of  the  Rio  Lajas  and 
of  the  Rio  Grande.  Here  the  level  plain  bor- 
dering the  lake  extends  entirely  through  the 
range  of  hills,  fonning  a  low  broad  gap  whose 
summit  is  but  fifty  feet  above  the  lake. 

The  manner  in  which  this  single  low  gap  was 
formed  is  described  at  some  length  in  a  later  part 
of  this  report  (page  142),  where  the  recent  geo- 
logical history  of  the  region  is  given.  It  may 
be  stated  here,  however,  that  the  gap  is  the  pro- 
duct of  the  familiar  process  of  stream  capture. 
Owing  to  the  decided  advantages  possessed  by 
the  streams  flowing  directly  to  the  Pacific  over 
those  flowing  eastward  at  first  to  the  bay  of  Nica- 
ragua and  afterwards  to  the  lake,  the  former 
were  able  to  cut  back  through  the  divide  into 
the  drainage  area  of  the  latter  and  divert  their 
headwaters.  In  this  way  an  eastward  flowing 
stream  originally  occupying  the  position  of  the 
Tola,  the  upper  Rio  Grande,  the  Guiscoyol  and 
the  Lajas  was  beheaded,  and  the  drainage  of  a 
large  part  of  its  basin  was  diverted  to  the  Pacific. 
The  deserted  vallev  of  this  stream  fonns  the  low 
gap  through  which  the  canal  route  is  located. 
It  is  so  broad  and  level  that  accurate  instru- 
mental work  is  required  to  determine  the  actual 
summit  of  the  Continental  Divide. 

The  Pacific  coast  in  the  southern  part  of  this 
region  is  formed  by  alternating  short  strips  of 
sandy  beach  and  bold  rocky  promontories.  The 
stretches  of  beach  are  fonned  by  the  silting  up 
of  deeply  cut  valleys  and  the  promontories  by 


APPENDIX    II.— GEOLOGIC    REPORT 


107 


the  truncated  points  of  ridges  which  extend 
down  to  the  coast  between  the  valleys.  To  the 
northward  of  Brito,  the  proposed  western  termi- 
nus of  the  canal,  at  the  month  of  the  Rio 
Grande,  the  hills  are  farther  inland  and  fewer 
sjnirs  reach  the  coast.  A  coastal  plain  of  some 
extent  is  here  developed,  increasing  in  width  to 
tlic  northward  until  it  passes  beneath  the  recqnt 
voU'anic  deposits  which  form  the  Jinotepe 
plateau. 

This  coastal  plain  probably  at  one  time  passed 
around  tlie  northern  end  of  the  divide  hills  and 
was  continuous  wuth  the  Rivas  plain  to  the 
east.  "With  the  formation  of  the  Jinotepe 
plateau  the  tnffs  of  which  it  is  composed  buried 
this  northern  portion  of  the  plain  and  piled  up 
against  the  end  of  the  divide  hills  three  or  four 
hundred  feet  in  thickness. 

Regions  Adjacent  to  the  Xicaraguax  De- 
PKEssioN. — The  Nicaraguan  depression  and  the 
AVcsteni  Divide  as  above  defined  and  described 
embrace  the  naiTow  belt  of  country  to  which  all 
feasible  variants  of  the  Nicaragua  Canal  route 
are  confined.  The  topography  of  the  adjacent 
regions,  however,  is  of  more  or  less  interest  and, 
particularly  from  hydrographic  considerations, 
has  a  direct  bearing  upon  canal  problems.  Its 
main  features  will  therefore  be  ver}^  briefly  de- 
scribed. 

Tlip  Lake-Caribbean  Divide, — Consider  first 
the  region  lying  north  of  the  San  Juan,  between 
the  lake  and  the  Caribbean.  As  alreadv  stated 
the  residual  hills  which  rise*above  the  ])fnoplain 
of  the  Nicaraguan  depression  increase  in  height 
and  numbers  toward  the  north,  finally  merging 
w^ith  tlie  mountains  of  northern  Nicaragua, 
where  they  reach  elevations  from  six  to  seven 
thousand  feet  above  tide.  Comparatively  little 
is  known  of  any  portion  of  this  region  except  its 
western  margin.     The  eastern  part  is  covered 


with  a  dense  tropical  forest,  is  almost  entirely 
without  settlement,  and  has  been  only  partially 
explored. 

The  divide  between  the  lake  and  the  Carib- 
bean drainage  passes  some  distance  to  the  west- 
ward of  the  axis  of  the  isthmus,  being  approxi- 
mately parallel  with  the  Pacific  coast  north- 
westward to  the  Matagalpa  river,  where  it  makes 
an  abrupt  bend  to  the  eastward,  passing  around 
the  basin  of  that  stream.  This  region  between 
the  lake  and  the  Caribbean  mav  be  described  as 
a  deeply  dissected  upland.  During  Tertiary 
time  it  was  doubtless  the  locus  of  intense  vol- 
canic activity,  but  subsequent  erosion  has  en- 
tirely destroyed  all  trace  of  the  original  (;on- 
structional  topography,  and  the  location  of  the 
vents  by  which  the  volcanic  rocks  were  erupted 
cannot  be  determined  from  the  present  fonn  of 
the  surface,  though  it  might  be  detennined  by 
a  systematic  study  of  the  distribution  and  varia- 
tions in  character  of  the  volcanic  rocks.  To- 
ward the  northern  end  of  the  lake,  opposite  Gra- 
nada, the  summits  of  the  hills  present  an  even 
skyline  as  though  they  were  remnants  of  a  pla- 
teau, but  this  surface  may  be  a  degradational 
rather  than  a  constructional  plain. 

The  streams  flowing  into  the  lake  have  base- 
leveled  their  vallevs  for  a  considerable  distance 
back  into  the  upland,  but  are  separated  by  sharp 
ridges  and  hills  which  occupy  the  divides.  Al- 
though the  higher  portions  of  the  divides  attain 
somewhat  unifonn  altitudes  which  increase 
northward,  the  uniformity  is  not  sufficient  to  de- 
termine the  former  existence  of  a  distinct  plain, 
and  it  is  probable  that  the  present  valleys  are 
carved  in  a  surface  which,  since  its  final  emer- 
gence above  sea  level,  has  always  had  ratlu^r 
high  relief.  So  far  as  known  the  trend  of  the 
ridg(h^  and  lines  of  hills  which  cK,*cupy  this  re- 
gi(m  have  been  determined  entirely  by  the  direc- 


108 


NICARAGUA   CANAL  COMMISSION 


tion  of  the  drainage  and  is  consequently  nearly 
east  and  west.  It  is  possible,  however,  that  the 
original  geological  structure  may  have  deter- 
mined the  position  and  direction  of  the  streams, 
although  they  occupy  the  position  which  they 
would  have  assumed  if  developed  normally  upon 
a  gently  arched  plateau. 

The  much  greater  rainfall  in  the  eastern  por- 
tion of  this  region  has  given  the  Caribbean 
streams  a  decided  advantage,  and  they  have 
pushed  the  di\'ide  westward  probably  some  dis- 
tance from  its  original  position.  A  few  cases 
occur  which  clearly  indicate  stream  diversion. 
The  most  striking  of  these  is  the  upper  portion 
of  the  Rio  Grande  which  flows  to  the  Caribbean 
north  of  Bluefields.  (See  Plate  II.)  This  river 
heads  in  the  high  valley  of  Matagalpa,  from 
which  it  flows  southwestward  for  thirty-five 
miles,  approaching  the  Viejo  within  about  five 
miles,  being  separated  from  that  stream  by  a 
level  swampy  plain.  The  Viejo  flows  southwest- 
ward  to  the  upper  end  of  Lake  Managua  and  it 
is  entirely  probable  that  the  upper  portion  of  the 
Eio  Grande  was  formerly  a  tributary^  of  the 
Viejo.  From  the  point  where  it  approaches 
most  nearly  to  the  Viejo  it  flows  southward  for  a 
distance  of  twenty-five  miles,  and  this  southerly 
direction  is  continued  in  a  tributary  which  enters 
at  that  point.  This  portion  of  the  stream  ap- 
pears to  have  been  at  one  time  a  part  of  the 
IMalacapoya  which  enters  the  head  of  Lake  Nica- 
ragua. From  the  point  of  nearest  approach  to 
the  Malacapoya  the  Rio  Grande  turns  abruptly 
back  to  the  northeast  and  for  a  distance  of  thirty 
miles  is  approximately  parallel  to  its  upper 
course  in  the  valley  of  Matagalpa.  It  appears 
highly  probable  that  the  Rio  Grande  by  reason 
of  the  greater  rainfall  in  the  eastern  part  of  this 
region  pushed  the  divide  westward  until  its 
headwaters  intercepted  the  upper  portion  of  the 


Malacapoya.  The  same  process  was  continued 
and  the  extended  headwaters  affected  another 
conquest,  diverting  a  large  tributary  *  of  the 
Viejo.  The  latter  capture  has  been  so  recent 
that  the  channel  of  the  diverted  stream  has  not 
been  perceptibly  lowered  and  a  part  of  its  waters 
in  the  wet  season  may  still  follow  their  former 
course  to  the  Viejo  across  the  inter\-ening 
swampy  plain.  A  few  other  cases  of  stream  di- 
version are  indicated  by  the  character  of  the 
present  stream  channels,  but  none  of  them  are 
so  striking  or  important  as  that  of  the  Rio 
Grande. 

Volcanic  Mouniain  Banges. — As  indicated 
above,  the  southern  margin  of  the  Nicaraguan 
depression  is  formed  by  the  foothills  of  the 
Costa  Rican  volcanic  range.  This  range  termi- 
nates to  the  northwestward  in  the  probably  ex- 
tinct volcano  Orosi.  It  contains  a  large  num- 
ber of  volcanic  peaks,  most  of  which  are  extinct 
while  a  few  are  quiescent  or  moderately  active. 
These  peaks  have  a  striking  linear  arrangement 
and  form  two  nearly  parallel  lines  of  vents. 
The  line  terminating  in  Orosi  extends  southeast- 
ward into  Costa  Rica,  passing  to  the  southward 
of  a  parallel  range  whose  northern  peak  is  the 
volcano  Turrialba.  These  two  lines  are  about 
ten  miles  apart,  but  their  peaks  are  so  high  that 
their  slopes  merge  and  they  form  a  single  range. 
If  the  line  connecting  the  northeasteni  series  of 
peaks  were  continued  to  the  northwestward 
through  the  southern  portion  of  Lake  Nicaragua 
it  would  coincide  very  nearly  ^vith  the  line  con- 
necting the  peaks  of  the  Nicaraguan  range.  The 
latter  range  terminates  to  the  southward  in  the 
extinct  volcano  of  Madera;  thence  it  stretches 
to  the  northwestward,  terminating  in  the  vol- 
cano Coseguina  w^hich  occupies  a  peninsula  pro- 
jecting into  the  gulf  of  Fonseca.  Between 
these  two  extreme  peaks  there  is  a  large  number 


APPENDIX  II.— GEOLOGIC  REPORT 


109 


of  extinct,  quiescent  or  active  volcanic  vents 
forming  more  or  less  isolated  mountains.  Of 
these  Ometepe,  Masaya,  Momotombo  and  sev- 
eral others  to  the  northwest  of  the  latter  have 
been  in  eruption  within  historic  times.  Others 
are  in  the  solfataric  stage,  while  still  others  ap- 
pear to  be  entirely  extinct.  The  group  of  peaks 
between  Momotombo  and  Coseguina  is  called 
the  Marabios  range. 

It  is  probable  that  the  vents  which  formed 
the  Costa  Rican  range  broke  out  upon  a  some- 
what elevated  plateau,  while  those  which  formed 
the  Nicaraguan  range  were  at  first  submarine. 
The  latter,  also,  are  farther  apart,  except  those 
northwestward  of  Momotombo,  which  form  the 
Marabios  range.  This  may  explain  the  greater 
height  and  massiveness  of  the  Costa  Rican  range, 
and  the  amount  of  material  erupted  from  the 
two  series  of  vents  may  not  differ  greatly. 

As  already  indicated  it  is  probable  that  the 
form  of  the  Pacific  coast  has  been  materially 
modified  by  this  recent  volcanic  activity.  The 
whole  of  the  country  between  the  northern  por- 
tion of  Lakes  Nicaragua  and  Managua  and  the 
Pacific  consists  entirely  of  recently  ejected  vol- 
canic material,  and  the  r^on  which  it  now  oc- 
cupies was  doubtless  a  portion  of  the  Pacific 
until  recent  geologic  times.  The  former  coast 
line  is  represented  on  the  sketch  map  forming 
Plate  n.  The  surface  of  this  newly-added  land 
is  composed  of  level  or  gently  sloping  plains, 
isolated  conical  volcanic  peaks  and  the  more 
crowded  peaks  of  the  Marabios  range.  Types 
of  the  entirely  isolated  peaks  are  Ometepe  and 
Momotombo.  Both  of  these  are  composed  of 
alternate  layers  of  lava  and  ash.  The  latter, 
however,  gives  them  their  perfect  conical  form. 
Both  have  been  in  eruption  within  historic  times 
and  considerable  smoke  still  comes  from  Momo- 
tombo.    (Plate  IV.)     Only  a  small  amount  of 


steam  and  sulphurous  vapors  are  at  present  emit- 
ted from  the  crater  of  Ometepe.  Modification 
by  the  ordinary  processes  of  erosion,  in  the  form 
of  these  steep  cones  of  unconsolidated  ash,  is  ex- 
tremely rapid  and  their  summits  vary  in  detail 
of  outline  from  year  to  year.  Madera  and  Za- 
patera  are  volcanoes  which  have  been  extinct 
for  some  time  and  the  agents  of  degradation 
have  materially  reduced  their  height  and  de- 
stroyed the  original  conical  form  of  their  sum- 
mits. The  unconsolidated  ash  has  been  largely 
removed  from  their  upper  portions,  leaving  only 
the  massive  lava  beds  in  place.  Hence  their 
formation  has  been  ascribed  to  a  different  form 
of  eruption  from  that  which  produced  Ometepe 
and  Momotombo.  It  is  probable,  however,  that 
the  summits  of  the  former  once  consisted  of  ash 
cones  and  that  the  eruptions  in  all  have  been  ac- 
companied by  more  or  less  explosive  violence  to 
which  the  unconsolidated  fragmental  material  is 
due.  The  lower  slopes  of  Mombacho  are  rather 
smooth  and  symmetrical,  but  instead  of  a  single 
cone  its  summit  is  truncated  and  forms  a  series 
of  ragged  peaks  which  surround  a  deep  depres- 
sion occupied  by  a  small  lake.  There  is  a  tra- 
dition that  this  mountain  formerly  had  a  conical 
summit  which  was  destroyed  by  an  explosive 
eruption.  The  present  appearance  of  the  moun- 
tain makes  it  extremely  probable  that  this  tra- 
dition is  based  upon  fact  Its  outline  closely  re- 
sembles that  of  Coseguina,  and,  as  is  well  known, 
the  latter  was  formerly  capped  by  a  symmetri- 
cal cone  which  was  blown  off  in  the  explosive 
eruption  of  1835.  This  was  perhaps  the  most 
violent  recorded  eruption  of  this  character  up 
to  the  time  of  the  eruption  of  Krakatoa  in  1883. 
Since  this  final  burst  of  activity  Coseguina  has 
remained  perfectly  quiet.  The  volcano  of  Ma- 
saya,  which  erupted  a  flow  of  lava  in  1858,  is  at 
present  a  mountain  of  moderate  height,  about 


110 


NICARAGUA   CANAL  COMMISSION 


2200  feet.  It  occupies  the  position,  however, 
of  a  mountain  which  may  once  have  been  very 
much  higher.  The  former  volcanic  peak  occu- 
pying this  position  was  destroyed,  not  by  an  ex- 
plosive eruption,  but  by  engulfment.  The  peak 
now  occupies  a  depressed  area  having  an  oval 
shaj^  and  regular  outline  about  four  by  six 
miles.  It  is  located  a  little  north  of  the  center 
of  this  depression,  the  northern  portion  of  which 
its  lavas  have  nearly  filled,  flowing  out  over  the 
edge  at  several  points  upon  the  surrounding 
countr\'.  The  outlines  of  the  depression,  how- 
ever, can  be  traced  continuously  with  the  ex- 
ception of  these  few  breaks  where  its  rim  has 
been  overtopped  by  the  recent  lava.  It  is  nearly 
everywhere  a  vertical  cliff,  descending  abruptly 
from  the  level  or  rolling  plain.  The  southern 
end  of  the  depression  which  is  not  filled  by  the 
lavas  of  Masaya  is  occupied  by  the  waters  of 
Lake  Masaya.  The  lake  has  a  crescentic  form 
and  is  bordered  on  the  convex  side  bv  the  verti- 
cal  cliffs  of  the  caldera  wall  rising  360  or  more 
feet  above  its  surface.  On  the  concave  side  it 
is  bordered  by  the  gentle  slope  of  the  lavas  of 
Masaya.  It  appears,  therefore,  that  a  portion 
of  the  volcanic  plateau  and  perhaps  a  volcanic 
cone  of  considerable  height  have  disappeared  by 
engulfment,  and  that  a  subsequent  eruption  at 
the  same  point  has  partially  filled  the  depression, 
building  up  a  new  cone  over  the  same  vent, 
though  not  to  so  great  a  height  as  the  former 
one.  This  new  cone  is  Masava.  It  has  the 
rather  low  dome  shape  characteristic  of  cones 
composed  largely  of  lava  flows  and  is  broadly 
truncated  by  a  double  crater.  A  similar  engulf- 
ment has  occurred  south  of  Masaya,  forming  the 
present  Lake  Apoya.  The  latter  depression  did 
not  coincide  with  a  volcano  but  occurred  on  the 
northern  side  of  Mount  Catrina,  a  low  ash  cone, 
carrying  down  one  side  of  the  latter  and  a  por- 


tion of  the  adjacent  plain.  The  depression  is 
somewhat  smaller  than  the  one  occupied  by  the 
lake  and  volcano  Masaya,  being  nearly  circular 
and  about  four  miles  in  diameter.  The  depres- 
sion  is  now  occupied  by  the  waters  of  Lake 
Apoya,  the  surface  of  which  is  260  feet  below 
the  lowTi?t  point  of  the  surrounding  rim  and 
about  1500  feet  below  the  highest  point  of  the 
rim.  This  highest  point  probably  coincides 
very  nearly  with  the  former  volcanic  peak,  al- 
though the  latter  being  composed  almost  entirely 
of  unconsolidated  ash  has  been  ver\"  much  re- 
duced  in  height  by  erosion.  Several  other  cal- 
dera lakes  of  this  type  occur  in  the  vicinity  of 
Managua. 

Volcanic  Plateaus, — Ilefercnce  has  been 
made  to  a  plateau  lying  southwest  of  Lake  ilan- 
agua  and  the  northern  end  of  Lake  Nicaragua, 
which  I  have  called  the  Jinotepe  plateau,  from 
the  principal  town  upon  it.  This  plateau  is 
composed  entirely  of  recently  ejected  volcanic 
material,  chiefly  a  partially  consolidated  vol- 
canic tuff  which  was  sj)read  out  in  the  form  of  a 
semi-liquid  mud.  The  plateau  has  an  altitude 
along  its  northeastern  margin  of  twelve  to  eigh- 
teen hundred  feet.  From  this  gently  undulat- 
ing summit  it  descends  gradually  southward  and 
southwestward  to  its  margin  against  the  older 
rocks  to  the  south  and  to  the  Pacific  coast.  The 
central  portion  of  the  plateau  has  been  but  little 
modified  by  erosion  and  probably  presen- es  verv' 
nearly  its  original  constructional  form.  This  is 
due  largely  to  the  porous  nature  of  the  volcanic 
ash  of  which  the  surface  is  composed.  The  rain 
waters  sink  into  the  ground  before  they  have  an 
opportunity  to  collect  into  sufficient  volume  to 
effect  any  modification  of  the  surface  except 
where  the  original  slopes  were  very  steep.  A 
belt  along  the  coast,  however,  has  been  rather 
deeply  dissected  by  stream  channels,  where  the 


NICARAGUA  CANAL  COMMISSION 


APPENDIX  2,  PLATE  IV 


VOLCANO  MOMOTOMBO  FROM  LAKE  MANAGUA. 


APPENDIX  II.— GEOLOGIC  REPORT 


111 


smaller  interniittcnt  tributaries  are  collected  into 
pcnnanent  trunk  streams  and  where  the  plateau 
has  a  decided  seaward  slope.  Toward  the  north 
and  nortlieast  the  plateau  is  terminated  by  a 
somewhat  abrupt  escarpment  which  separates  it 
from  the  lower  plain  of  Leon  and  from  the  plain 
lying  between  Lakes  Managua  and  Nicaragua, 
These  lower  plains  have  precisely  the  same  ori- 
gin as  tlie  Jinotepe  plateau,  and  it  is  quite  pos- 
sible that  at  one  time  the  lower  and  higher  plains 
mav  have  been  continuous,  but  were  subse- 
quently  separated  by  a  depression  of  the  region 
to  the  northeast.  In  other  words,  the  escarp- 
ment which  limits  the  .Tinotepe  plateau  to  the 
north  and  east  may  possibly  mark  the  line  of  a 
rather  recent  fault.  The  escarpment  has  been 
deeply  scored  by  stream  channels  so  that  it  does 
not  now  have  the  characteristic  form  of  a  re- 
cent fault  scai-p  but  the  character  of  the  ma- 
terials of  which  it  is  composed  are  such  that  it 
would  be  rapidly  modified,  and  so  retain  its 
original  form  but  a  short  time. 

CLIMATE. 

The  climatic  conditions  prevailing  in  this  re- 
gion have  so  direct  a  bearing  upon  its  geology 
and  physiography  that  a  brief  statement  of  the 
more  important  characteristics  of  the  climate  is 
essential.  Lying  only  ten  degrees  north  of  the 
equator  the  climate  of  the  region  is  tropical, 
frost  being  entirely  unknown.  Furthermore 
since  it  forms  a  narrow  belt  between  two  oceans 
its  climate  is  also  insular,  the  annual  range  of 
temperature  being  very  much  smaller  than  all 
continental  areas  experience. 

Amount  and  Distribution  of  Rainfall. — 
Throughout  the  greater  part  of  tho  year  the 
trade  winds  prevail  with  fairly  constant  direction 
and  force.  These  winds  are  probably  deflected 
slightly  to  the  northward  by  the  high  voncanic 


range  of  Costa  Rica,  and  to  the  southward  by 
the  mountains  of  central  and  northern  Nicara- 
gua. Tho  low  gap  across  the  isthmus  constitu- 
ting the  Nicaraguan  depression,  thus  receives 
considerably  more  wind  than  would  be  due  to 
the  nonnal  trades.  It  is  probably  this  conges- 
tion of  the  air  currents  that  causes  the  excep- 
tional precipitation  in  this  region.  Coming  from 
the  warm  Caribbean  sea  the  trade  winds  are 
saturated  with  moisture,  and  as  they  strike  the 
slightly  elevated  land  forming  the  isthmus  the 
precipitation  is  there  veiy  abundant.  Within 
the  zone  of  maximum  precipitation  which  em- 
braces the  coastal  plain  and  the  adjacent  hills, 
forming  a  belt  from  50  to  100  miles  wide,  the 
annual  raihfall  reaches  nearly  300  inches.  Be- 
yond this  belt  at  increasing  distances  from  the 
Caribbean  coast  it  decreases  very  rapidly,  and  in 
the  western  part  of  the  region  the  annual  rain- 
fall is  less  than  a  third  of  that  on  the  eastern 
coast. 

More  important,  however,  than  the  absolute 
amount  of  rainfall  is  its  distribution  throughout 
the  year.  The  isthmus  may  be  divided  into  two 
distinct  and  well  marked  subdivisions  by  a  line 
coinciding  approximately  with  the  present  di- 
vide between  lake  and  Caribbean  drainage  and 
crossing  the  San  Juan  near  the  point  where  that 
river  leaves  the  lake.  In  the  eastern  division 
the  rain  is  distributed  with  tolerable  uniformity 
throughout  the  entire  year.  There  are  some 
years  in  which  little  rain  falls  for  a  period  of 
three  or  four  weeks  in  August  and  September, 
but  this  scarcely  constitutes  a  dry  season.  In 
the  western  division,  on  the  other  hand,  there  is 
a  distinct  drv  season  of  five  or  six  months,  in 
which  there  is  practically  no  rainfall.  The  rain 
begins  about  the  middle  of  May  when  the  trade 
winds  become  less  constant  and  an  occasional 
storm  comes  from  the  northwest. 


112 


NICARAGUA   CANAL  COMMISSION 


Physiographic  Effects. — ^These  climatic  dif- 
ferences between  the  eastern  and  western  por- 
tions of  the  region  give  rise  directly  to  very 
striking  differences  in  vegetation,  and  either  di- 
rectly or  indirectly  to  differences  in  the  appear- 
ance and  structure  of  the  soils,  in  the  topo- 
graphic  forms  of  the  land  surface  and  in  the  ef- 
fectiveness of  various  physiographic  processes. 

Eastern  Division, — The  eastern  division,  in 
which  the  rain  is  distributed  with  tolerable  uni- 
formity throughout  the  year,  is  covered  with  a 
dense  tropical  forest.  The  only  breaks  in  this 
forest  are  the  stream  channels  and  the  open 
lagoons,  or  those  so  recently  silted  up  that  the 
soil  is  not  sufficiently  firm  to  support  large  trees. 
Throughout  this  region  there  are  no  human  hab- 
itations except  in  the  few  small  towns  along  the 
coast  and  an  occasional  hut  in  a  clearing  upon 
the  banks  of  the  rivers.  There  are  no  roads  or 
other  means  of  intercourse  except  by  way  of  the 
streams. 

The  most  directly  apparent  effect  of  the  forest 
is  to  protect  the  land  surface  from  erosion.  The 
falling  rain  is  intercepted  by  the  canopy  of  foli- 
age, and  filters  down  gradually  to  the  surface, 
where  the  smaller  vegetation  consists  largely  of 
palms  whose  broad  leaves  afford  a  still  further 
protection  so  that  the  soil  never  receives  the  di- 
rect impact  of  the  raindrops.  Since  there  are 
no  forest  fires  the  surface  is  more  or  less  per- 
fectly covered  with  forest  litter  which  acts  as  a 
further  protective  covering  to  the  soil.  The 
character  of  the  soil  will  be  described  more  fully 
in  treating  of  the  regolith,  but  it  may  be  stated 
here  that  the  surface  of  this  eastern  division, 
wherever  it  rises  above  the  level  flood-plains  of 
the  streams,  is  composed  of  a  tenacious  red  clay. 
This  clay  never  becomes  dry  enough  to  be  in- 
tersected by  shrinkage  cracks  and  is  of  course 
never  loosened  by  the  action  of  frost.    Although 


it  is  penetrated  by  roots  and  to  some  extent  by 
the  burrows  of  insects,  it  nevertheless  resists 
degradation  to  a  remarkable  degree.  It  was 
often  observed  that  during  a  heavy  rainfall  the 
water  flowing  from  the  st^ep  hillsides  would  be 
scarcely  at  all  discolored  by  sediment.  After 
a  careful  study  of  the  region  it  was  concluded 
that  the  absence  of  frost  more  than  counterbal- 
ances the  enormous  rainfall  and  that  degradation 
of  the  surface  is,  on  the  whole,  slower  than  in 
temperate  regions  where  the  rainfall  is  less  than 
a  quarter  of  that  in  Nicaragua  but  where  the 
surface  soil  is  thoroughly  loosened  by  the  action 
of  frost.  Many  of  the  small  brooks  which  carry 
water  throughout  the  year  and  have  very  steep 
gradient,  flow  in  shallow  channels  cut  in  this 
clay.  The  clay  often  forms  cascades  and  ap- 
pears to  offer  more  resistance  to  corrasion  than 
many  varieties  of  rock.  Although  the  hill 
slopes  are  steep  they  are  comparatively  smooth, 
not  deeply  gullied,  as  is  usually  the  case  in  tem- 
perate regions,  and  it  is  only  after  the  water  has 
collected  in  considerable  volume  that  it  is  able 
to  lower  its  channel  through  the  clay  to  the  un- 
derlying rock.  A  further  effect  of  the  vegeta- 
tion, and  hence  indirectly  of  the  climate,  is  that 
many  of  the  streams  are  filled  with  an  abundant 
growth  of  vegetation  by  which  their  current  is 
checked  and  their  effectiveness  as  an  eroding 
agent  correspondingly  reduced.  The  decay  of 
vegetable  matter  is  so  rapid  that  there  are  no 
considerable  accumulations  of  such  matter  either 
in  the  forest  generally  or  in  the  lagoons  and 
swamps.  In  boring  through  the  alluvial  flood- 
plains,  many  of  which  have  once  been  open  la- 
goons, while  an  occasional  Ic^  was  encountered, 
nothing  was  found  in  the  nature  of  peat,  and  the 
silt  contains  only  a  relatively  small  proportion 
of  finely  comminuted  organic  matter.  On  well- 
drained  surfaces,  such  as  moderately  steep  hill- 


APPENDIX  II.— GEOLOGIC  REPORT 


113 


sides,  there  is  generally  no  humus  layer.  The 
red  soil,  practically  free  from  incorporated  or- 
ganic matter,  forms  the  surface,  only  in  part 
covered  by  the  forest  litter. 

Western  Division, — ^In  the  western  division, 
particularly  that  portion  of  it  lying  west  of  the 
lake,  the  distribution  of  the  rainfall  produces  a 
distinctly  different  type  of  vegetation.  This  re- 
gion is  characterized  by  open  savannas  in  which 
the  trees  are  small  and  grow  in  isolated  patches, 
the  greater  part  of  the  surface  being  open  and 
covered  with  grass  or  small  bushes.  These  sa- 
vannas are  probably  due  to  deforesting,  in  part 
by  clearing  for  cultivation  and  grazing,  and  in 
part  by  fires.  Wherever  a  forest  covers  the  sur- 
face its  character  is  entirely  different  from  that 
in  the  eastern  division.  It  has  the  thorny  habit 
and  scant  foliage  which  characterizes  the  vege- 
tation of  a  semi-arid  region.  The  light  is  not 
cut  off  by  the  foliage  of  the  higher  trees,  and 
hence  the  smaller  herbaceous  vegetation  is  much 
more  abundant  than  in  the  eastern  division. 
Fires  prevail  in  the  dry  season  so  that  the  forest 
litter  does  not  accumulate,  and  at  the  beginning 
of  the  wet  season,  before  the  vegetation  is  re- 
newed, the  surface  is  entirely  unprotected  from 
the  effects  of  the  heavy  rainfall  which  inaugu- 
rates that  season. 

Red  soil  is  rarely  seen  west  of  the  lake,  the 
prevailing  colors  being  blue,  bluish-gray  or 
black,  and  this  is  quite  independent  of  the  char- 
acter of  the  rock  from  which  it  is  derived,  since 
the  rocks  are  essentially  the  same  as  those  which 
yield  red  soils  in  the  eastern  division.  Toward 
the  end  of  the  dry  season  the  surface  is  inter- 
sected by  many  deep  cracks,  often  two  or  three 
inches  wide  and  as  many  feet  deep,  which  ef- 
fectually destroy  the  coherence  of  the  clay. 
This  alternate  saturation  and  baking  of  the  soil, 

therefore,  effects  somewhat  the  same  result  as 
8 


that  accomplished  elsewhere  by  frost.  It  also 
permits  the  incorporation  of  much  organic  mat- 
ter with  the  upper  portions  of  the  soil,  forming 
an  exceptionally  thick  humus  layer.  From  these 
and  perhaps  other  conditions  it  results  that  the 
smaller  rainfall  of  the  western  division  is  a  very 
much  more  efficient  agent  ot  erosion  than  the 
greater  rainfall  of  the  eastern  division. 

The  effect  of  these  climatic  conditions  is  seen 
in  the  topography  which  characterizes  the  region 
west  of  the  lake.  The  hills  are  extremely  steep 
and  deeply  gullied.  At  the  mouth  of  each  ra- 
vine there  is  an  alluvial  cone,  showing  that  a 
heavv  load  of  coarse  and  fine  detritus  is  moved 
by  the  occasional  flood  which  the  ravine  carries. 
The  depth  of  the  residual  material,  the  regolithy 
is  also  very  much  less  on  the  west  side  than  it  is 
on  the  east.  This  is  doubtless  due  in  part  to  the 
fact  that  the  conditions  of  rock  weathering  are 
less  favorable  in  the  former  than  in  the  latter 
region,  but  it  is  also  due  in  part  to  the  more 
favorable  conditions  under  which  the  agents  of 
degradation  act.  Both  of  these  factors,  how- 
ever, are  directly  dependent  on  climate. 

Another  factor  which  on  the  west  side  may 
be  effective  in  modifying  topographic  forms  is 
wind  erosion.  During  the  dry  season  when  the 
protecting  vegetation  has  been  removed  by 
forest  fires,  the  steady  force  of  the  trade  winds 
raises  clouds  of  dust,  and  the  total  amount  of 
transportation  effected  by  this  agency  must  be 
very  considerable.  The  effects  are  most  notice- 
able on  the  lake  and  ocean  beaches  where  the 
sand  is  driven  with  great  force  and  piled  up  in 
dunes.  Roads  on  which  there  is  sufficient  travel 
to  keep  down  the  vegetation  are  usually  sunk 
below  the  surface  of  the  adjacent  country.  The 
track  is  often  bordered  by  a  vertical  bank  from 
five  to  fifteen  feet  high,  and  a  part  of  this  ero- 
sion is  doubtless  due  to  w4nd  action. 


114 


NICARAGUA   CANAL  COMMISSION 


ROCK  FORMATIONS. 

Conditions  for  Study. — The  geology  of  the 
region  uiiJer  eonsideration  has  been  examined 
in  detail  onlv  in  the  vicinitv  of  the  route  of  the 
proposed  canal.  Even  where  studied  most  care- 
fully the  relations  of  the  various  rock  forma- 
tions  are  extremely  obscure.  This  obscurity 
arises  chiefly  from  the  nature  of  the  exposures 
which  must  be  depended  upon  in  making  out 
these  relations.  East  of  the  lake  rock  exposures 
are  very  infrequent,  and  it  is  practically  impos- 
sible from  them  alone  to  determine  the  relations 
of  the  various  rock  formations.  The  vegetation 
is  so  abundant  that  no  distant  views  can  be  ob- 
tained, and  the  information  which  can  usually 
be  derived  from  a  broad  study  ot*  the  topo- 
graphy is  entirely  w^anting.  The  extreme 
depths  to  which  the  rocks  are  decayed  and  tlie 
uniform  mantle  of  red  clav  which  covers  their 
outcrojis  effectually  conceal  their  distribution 
and  relations.  The  larger  streams,  as  ah*eady 
explained,  are  chiefly  flowing  in  old  valleys 
which  they  are  now  silting  up.  Since  they  are 
not  corrading  their  beds,  their  channels  furnish 
exposures  of  materials  other  than  alluvial  only 
where  they  hap])en  to  impinge  upon  the  adjoin- 
ing hills  in  their  lu'oad  meandei's.  The  only 
exception  to  this  general  statement  is  the  San 
Juj^n  l)etween  Castillo  and  ilachuca.  The  con- 
ditions west  of  Lake  Nicaragua  are  somewhat 
more  favorable.  The  vegetation  is  iu>t  so  abun- 
dant, and  the  removal  of  the  residual  matter  has 
more  nearly  kept  pace  with  the  rock  decay;  also 
the  slopes  are  more  abnipt,  and  most  of  the 
streajjis  are  corrading  their  channels  except  in 
the  lower  portions  of  their  valleys. 

Xo  attemj)t  was  made  in  the  field  to  do  areal 
mapping,  and  the  distribution  of  the  formations 
represented  on  the  accompanying  map  (Map 
Xo.  1,  Sheet  2)  must  therefore  be  regarded  as 


in  most  cases  only  approximate.  For  the 
reasons  stated  above  the  most  detailed  areal  work 
would  secure  but  little  additional  information 
concerning  distribution  in  some  portions  of  the 
region. 

Classification  of  the  Rocks. — The  rocks  of 
the  region  are  placed  in  two  groups,  Tertiary 
and  post-Tertiarv\  Each  includes  both  igneous 
and  sedimentary  formations.  Xo  rocks  cer- 
tainly  older  than  the  Tertiaiy  occur  along  the 
line  of  the  canal,  although  such  have  been  re- 
ported from  northern  Xicaragua  and  also  from 
central  Costa  Rica.  The  Tertiary  sedimentary 
formations  include  the  Brito  and  Machuca. 

Bkito  Formation. — Distribution. — With  the 
exception  of  a  few  areas  of  intrusive  igneous 
rocks,  the  strip  of  land  between  Lake  Xicaragua 
and  the  Pacific  is  occupied  entirely  by  the  Brito 
formation.  It  extends  from  the  Sapoa  river  to 
a  point  o})posite  the  island  of  Zapatera.  Rem- 
nants of  the  formation  are  also  found  along  the 
lake  shore  to  the  southeast  of  Sapoa,  and  its 
present  outcrops  may  extend  continuously  east- 
ward to  the  area  occupied  by  the  Machuca  sand- 
stone. To  the  southward  the  formation  is  prob- 
ably covered  bv  the  recent  lavas  of  the  Costa 
Rican  volcanoes.  It  also  probably  extcmds  some 
distance  to  the  northwest  of  Zapatera  where  it 
is  covered  by  the  recent  tuffs  which  form  the 
Jinotcpe  plateau. 

Lithologic  Character. — The  fonnation  presents 
considerable  variety  in  its  lithological  composi- 
tion, but  it  has  not  vet  been  suflicientlv  studied 
to  permit  of  its  subdivision,  even  if  this  may  be 
eventually  ])ossible.  Much  the  larger  mass  of 
the  formation  consists  of  somewhat  calcareous 
non-fissile  shale.  When  fresh  this  is  bluish- 
urav  and  weathers  to  a  yellowish  or  brownish 
color.  Distributed  through  the  shale  are  nu- 
merous beds  of  sandstone.     These  are  also  some- 


APPENDIX  II.— GEOLOGIC  REPORT 


115 


what  calcareous  and  doubtless  contain  a  consid- 
erable proportion  of  volcanic  ash.  The  sand- 
stone beds  vary  in  thickness  from  a  few  inches 
to  two  or  three  feet  and  occur  singly  or  in 
groups.  The  latter  are  sufficiently  heavy  to  ma- 
terially affect  the  topography  in  some  places. 
These  sandstones,  like  the  shales,  are  blue  when 
entirely  fresh,  but  are  always  weathered  at  the 
surface  to  some  shade  of  yellow  or  brown.  The 
hills  immediately  west  of  Rivas,  rising  abruptly 
above  the  Rivas  plain,  are  due  chiefly  to  the 
presence  of  these  resistant  sandstones.  They 
occur  most  abundantly,  however,  near  the  Pa- 
cific coast  and  are  well  exposed  in  the  headland 
northwest  of  the  Rio  Grande  valley  at  Brito. 
The  beds  here  have  a  general,  though  some- 
what variable,  dip  to  the  southwest,  hence  the 
higher  portions  of  the  formation  make  the  cliffs 
along  the  Pacific.  This  seems  also  to  be  its 
most  variable  portion.  In  addition  to  the  shales 
which  constitute  its  greatest  bulk  to  the  east- 
ward, it  here  contains  also  beds  of  sandstone, 
conglomerate  and  coarse  volcanic  breccia  on  the 
one  hand,  and  on  the  other  marly  beds  and 
lenses  of  pure  limestone.  Forming  a  part  of 
the  headland  south  of  Brito  is  a  bed  of  lime- 
stone something  over  a  hundred  feet  in  thick- 
ness. Small  outcrops  of  this  bed,  or  one  very 
similar,  have  been  noted  at  several  other  locali- 
ties to  the  eastward  in  the  Divide  hills.  Its 
limited  extent  is  due  in  part  to  erosion,  since 
the  dip  of  the  bed  would  carry  it  above  the  tops 
of  most  of  the  hills  to  the  eastward,  but  it  is 
doubtful  if  its  original  extension  was  very  great. 
Several  of  the  limestone  outcrops  noted  are 
probably  small  lenses  in  the  shale  and  not  con- 
nected with  the  more  continuous  bed  at  Brito. 
A  portion  of  this  limestone  has  a  peculiar  con- 
cretionarv  structure,  some  of  the  concretions  at- 
taining  a  diameter  of  an  inch  and  a  half  while 


other  portions  of  the  bed  are  oolitic.  Imme- 
diately west  of  this  exposure  of  limestone,  form- 
ing a  group  of  islets  nearly  covered  by  high 
tide,  is  a  very  coarse  volcanic  conglomerate  or 
breccia.  Tlie  larger  fragments  are  a  foot  or 
more  in  diameter  and  quite  angular,  and  from 
this  extreme  they  grade  downward  to  small  peb- 
bles some  of  which  are  well  rounded.  The  pres- 
ent relations  indicate  that  the  conglomerate  is 
the  stratigraphical  equivalent  of  the  limestone, 
replacing  it  within  a  few  yards.  In  some  places 
the  two  rocks  are  seen  to  merge,  the  limestone 
containing  numerous  angular  fragments  of  vol- 
canic rock.  At  other  points  along  the  coast  both 
north  and  south  of  Brito  similar  conglomerates 
occur.  Their  bedding  is  extremely  irregular, 
and  they  afford  evidence  of  having  been  formed 
rapidly  and  near  the  source  from  which  their 
constituents  were  derived.  While  it  is  possible 
that  the  source  of  this  material  mav  have  been 
to  the  eastward  it  seems  much  more  likely  that 
it  came  from  volcanic  vents  to  the  southwest, 
from  volcanoes  which  have  been  entirely  re- 
moved  by  the  waves  of  the  Pacific. 

Although  their  connection  has  not  been  con- 
tinuously traced  it  is  assumed  that  the  sedimen- 
tary rocks  found  at  various  points  along  the 
southern  margin  of  the  lake  east  of  Sapoa,  be- 
long to  the  Brito  formation.  This  region  was 
examined  by  coasting  along  the  lake  shore,  so 
that  it  was  chiefly  the  rocks  fonning  the  pro- 
jecting headlands  which  were  observed.  These 
consist  almost  entirely  of  sandstones  very  simi- 
lar in  appearance  to  the  sandstones  found  inter- 
bedded  with  the  Brito  shales,  and  also  con- 
glomerates and  breccias  similar  to  those  occur- 
ring at  various  points  along  the  Pacific  coast. 

Structure. — (See  general  geological  sections, 
Plate  XVI.)  The  Brito  formation  wherever  ob- 
served w^as  foimd  to  be  intersected  by  numerous 


116 


NICARAGUA   CANAL  COMMISSION 


joint  planes  as  shown  in  Plate  V.  In  some 
places  these  occur  as  two  well-developed  sets  of 
approximately  parallel  planes  which  intersect 
each  other  at  right  angles.  In  others  the  joint 
planes  are  vers-  numerous  and  irregular,  cutting 
the  beds  in  all  directions.  The  latter  form  is 
less  common  and  appears  to  be  confined  to  rather 
narrow  zones  where  sh(*aring  and  faulting  have 
probal)ly  taken  place.  The  frequency  of  the 
joint  planes  varies  with  the  thickness  of  the 
beds.  The  rhomboidal  blocks  into  which  the 
beds  of  shale  and  sandstone  are  broken  usually 
have  diametei*s  approximately  equal;  that  is,  the 
more  massive  the  original  beds  the  farther  apart 
are  the  intersecting  joint  planes.  These  joints 
have  permitted  the  percolation  of  surface 
waters  to  great  depths  and  have  facilitated  the 
deep  Aveathering  \vhicli  is  generally  observed. 
The  weathering  proceeding  outward  from  the 
joints  has  resulted  in  the  fonnation  of  concentric 
layers  about  a  core,  which  coincides  with  the 
center  of  the  original  rhomboidal  block.  The 
accompanying  illustration,  Plate  V,  is  from  a 
photograph  of  the  Brito  sandstone  exposed  in  a 
ravine  near  La  Flor.  It  shows  the  effect  of  the 
jointing  and  to  some  extent  the  subsequent  con- 
centric weathering  in  the  sandstone.  The  re- 
sulting rounded  blocks  in  some  places  give  the 
appearance  of  a  rude  rubble  wall.  In  the  vi- 
cinity of  Las  Lajas  the  horizontal  sandstone  beds 
have  been  laid  bare  by  the  action  of  the  waves, 
and  where  the  rhomboidal  blocks  produced  by 
jointing  have  been  rounded  by  concentric  weath- 
ering, the  appearance  is  that  of  a  cobble  pave- 
ment. 

The  Brito  formation  has  suffered  onlv  a  mod- 
erate  amount  of  disturbance  since  its  beds  were 
deposited.  Where  its  rocks  are  best  exposed 
along  the  Pacific  coast  numerous  small  faults 
are  observed,  the  displacement  in  many  cases 


being  but  a  few  inches.  The  inclination  of  tlie 
beds  is  generally  under  20°  though  in  a  few  lo- 
calities the  disturbance  has  been  much  greater 
and  the  dips  increase*  up  to  the  vertical.  Xeg- 
lecting  these  minor  iiTcgularities  the  dominant 
structure  is  a  broad  anticline  whose  axis  extends 
in  a  northwest-southeast  direction  approximately 
parallel  with  the  Pacific  and  lake  shores  and  a 
short  distance  southwest  of  the  latter  where  the 
beds  are  a|>proximately  horizontal.  The  greater 
poi*ti(>n  of  the  region  between  the  lake  and  the 
Pacific,  therefore,  is  occupied  by  the  western 
limb  of  the  anticline  and  has  prevailing  south- 
west dips.  From  San  Jorge  to  Lajas  the  dips 
are  somewhat  variable  but  generally  to  the 
northeast.  The  greater  part  of  the  eastern  limb 
of  the  anticline  is  covered  bv  the  lake.  The  nu- 
merous  exposures  of  the  Brito  fonnation  along 
the  southern  margin  of  the  lake  from  the  Sapoa 
to  the  Kio  Orosi  belong  to  this  eastern  limb  of 
the  anticline,  and  the  beds  have  northeasterly 
dips  of  5°  to  30°.  The  strike  of  these  beds  is 
not  strictly  parallel  with  that  of  the  beds  on  the 
Pacific  coast.  They  converge  slightly  toward 
the  northwest,  indicating  a  pitch  of  the  anti- 
cline in  that  direction. 

The  exposures  of  the  Brito  formation  are  so 
infrequent  and  the  dips  are  so  variable  that  no 
satisfactorv'  measure  of  the  thickness  of  the  for- 
mation can  be  obtained.  Taking  the  observed 
dips  between  the  Pacific  coast  and  the  lake  shore 
the  thickness  exposed  is  estimated  at  about 
10,000  feet.  This  of  course  is  not  the  total 
thickness  of  the  formation,  since  the  bottom  is 
not  exposed  at  the  axis  of  the  anticline.  Also 
the  fonnation  has  undoubtedly  suffered  an  un- 
known but  considerable  diminution  in  thickness 
by  erosion,  and  there  are  no  data  for  determin- 
ing the  thickness  of  strata  which  have  been  re- 
moved from  the  highest  beds  now  obsen^ed. 


NICARAGUA  CANAL  COMMISSION 


APPENDIX  2,  PLATE  V 


THE  BRITO  FORMATION   NEAR  LA  FLOP. 


Interbedded  aandatone  and  shale  ahowlng  intersecting  jolnta  and 
concentric  weathering. 


APPENDIX  II.— GEOLOGIC  REPORT 


117 


Utilization, — ilost  of  tlie  ^JalKlstones  of  the 
Brito  formation  are  too  thin-bedded  for  utiliza- 
tion as  building  stone.  This  is  the  character  of 
the  beds  exposed  in  the  northern  Brito  headland, 
although  a  part  of  them  at  least  might  be  util- 
ized for  concrete  and  rip-rap  work.  Abont  half 
a  mile  back  from  the  coast  a  group  of  heavy 
sandstone  beds  occurs  in  the  shales.  Thev  form 
a  spur  from  the  hills  to  the  north  extending 
out  a  short  distance  into  the  Rio  Grande  valley. 
These  beds  would  probably  yield  a  good  quality 
of  building  stone.  They  would  be  easily  quar- 
ried in  dimensional  blocks  up  to  twenty  or  more 
inches  in  thickness:  would  dress  readilv  and  be 
as  durable  as  the  average  sandstone. 

Age  of  the  Formation, — The  greater  part  of 
the  Brito  formation  is  apparently  barren  of  or- 
ganic remains.  The  only  locations  at  which  fos- 
sils have  been  found  are  on  or  near  the  Pacific 
coast.  This,  however,  may  be  due  to  the  fact 
that  the  rock  exposures  are  not  elsewhere  of  such 
a  character  as  to  fa(^ilitate  the  discover'  of  fos- 
sils,  and  the  latter  may  possibly  be  more  gener- 
ally distributed  than  present  knowledge  would 
indicate.  The  fossils  are  confined  almost  whollv 
to  the  limestones  and  marlv  beds.  Thev  con- 
sist  of  corals,  moluscan  and  foraminiieral  re- 
mains. The  latter  are  especially  abundant. 
The  rather  meager  collections  have  been  sub- 
mitted to  Dr.  Dall  for  determination.  He  pro- 
nounces them  Oligocene  and  probably  identical 
with  the  foraminiferal  beds  described  bv  Hill 
from  the  Caribbean  coast  at  Panama.  One  of 
the  most  abimdant  forms  is  a  small  numulite, 
orbitoides,  probably  forbcsei  which  is  character- 
istic of  the  lower  Oligocene.  The  moluscan  re- 
mains were  collected  on  the  Pacific  coast  about 
seventy-five  miles  northwest  of  Brito  in  what 
was  supposed  to  be  a  higher  portion  of  the  same 
formation.     Dr.  Dall  states  that  these  have  the 


upper  Oligocene  aspect  though  there  are  not 
enough  of  them  to  be  conclusive.  lie  thus  con- 
firms the  view  entertained  in  the  field  that  suc- 
cessively higher  beds  in  tlie  Brito  formation  are 
exposed  along  the  coast  toward  the  northwest. 

In  addition  to  the  fossils  on  which  is  based 
the  above  conclusion  concerning  the  age  of  the 
Brito  formation  it  also  contains  rather  abundant 
plant  remains.  They  are  in  the  form  of  drift- 
wood and  coal,  and  as  vet  no  remains  sufficientlv 
well  preserved  for  identification  have  been  dis- 
covered. Associated  with  the  coarser  sandstones 
are  numerous  blocks  of  wooil  whose  rounded 
forms  suggest  that  they  are  fragments  of  drift 
which  were  incorporated  with  the  sand  and 
gravel  while  it  was  accumulating.  In  some 
cases  they  still  contain  a  large  proportion  of 
their  original  carbon,  and  in  others  this  has  been 
more  or  less  perfectly  replaced  by  silica  or  iron 
pyrites.  The  coal  occui*s  associated  with  the 
finer  sediments,  and  although  a  careful  search 
was  made,  the  thickest  seam  observed  was  under 
half  an  inch.  AVhile  sufficient  carbonaceous 
matter  is  sometimes  disseminated  through  the 
shales  to  give  them  a  black  color,  no  indications 
were  found  pointing  to  the  existence  of  work- 
able coal  deposits  in  the  region  examined. 

Coal  in  workable  quantity  has  been  reported 
from  the  region  southwest  of  the  lake,  between 
the  lake  shore  and  the  Costa  Rican  volcanoes. 
The  exact  localitv  is  on  the  Rio  Hacienda, 
twelve  miles  from  its  mouth.  It  was  not  visited 
and  no  samples  of  the  coal  were  seen,  so  tliat  the 
report  lacks  verification.  There  appears  to  be 
no  reason,  however,  why  conditions  favorable 
for  coal  accumulation  should  not  have  prevailed 
in  some  portions  of  this  region  during  the  depo- 
sition of  the  Brito  beds. 

Maciiuca  Pormation. — Distribution. — The 
immediate  margins  of  the  San  Juan  valley  from 


118 


NICARAGUA   CANAL  COMMISSION 


the  lake  eastward  to  Castillo  are,  so  far  as 
known,  composed  entirely  of  igneous  rocks. 
From  a  point  a  few  miles  below  Castillo  to  an- 
other midwav  between  ]\[achuca  and  the  Boca 
San  Carlos,  tlie  rocks  are  largely  sedimentary, 
although  they  contain  some  igneous  rocks  in 
the  form  of  small  dikes.  These  sedimentary 
rocks  constitute  the  Machuca  formation.  Its 
present  extent  is  known  only  in  the  immediate 
vicinity  of  the  river.  The  region  south  of  the 
upper  San  Juan,  foraiing  the  lower  valleys  of 
the  Frio  and  Poco  Sol,  is  geologically  unex- 
plored. It  is  therefore  possible  that  the  Ma- 
chuca formation  may  extend  westward  through 
this  region  and  be  nearly,  if  not  quite,  contin- 
uous Avith  the  outcrops  of  the  Brito  formation 
south  of  the  lake.  TTntil  this  connection  is  es- 
tablished, however,  the  original  continuity  of 
the  two  formations  is  a  matter  of  doubt. 

Lithologic  Character. — The  rock  exposures  in 
this  region  to  the  eastward  of  Castillo  are  veiy 
much  less  satisfactory  than  those  along  the  Pa- 
cific coast;  hence  the  character  of  the  Machuca 
formation  is  not  so  well  known  as  is  that  of  the 
Brito.  Like  the  latter,  it  appears  to  consist 
chiefly  of  calcareous  shales  with  w^hich  sand- 
stones are  interbedded.  The  constituents  of  the 
rocks  are  largely  igneous  in  their  origin,  but 
there  are  no  coarse  conglomerates  or  breccias 
such  as  occur  in  the  Brito.  Also  no  pure  lime- 
stones or  distinctly  marly  beds  have  been  dis- 
covered, although  the  examination  of  the  forma- 
tion has  not  been  sufficiently  exhaustive  to  en- 
able one  to  say  that  such  beds  do  not  occur. 

Structure, — (See  general  geological  sections, 
Plate  XVI.)  The  exposures  are  comparatively 
few  in  which  the  dip  of  the  Machuca  sandstones 
can  be  determined.  At  the  Cano  Bartola  the 
dip  is  about  15°  and  to  the  north.  At  Machuca 
it  is  20°  and  to  the  northwest.     These  dips  sug- 


gest the  presence  of  a  synclinal  basin,  the  south- 
em  end  of  which  is  crossed  by  the  San  Juan. 
They  are  not  sufficient,  however,  to  locate  its 
axis.  Although  in  general  the  dips  are  light, 
the  formation  has  suffered  considerable  local  dis- 
turbance. Breccias,  probably  due  to  faulting, 
have  been  observed  at  several  points,  the  best 
example  being  the  ledge  which  projects  into  the 
river  opposite  the  mouth  of  the  Machuca.  Also 
numerous  sharp  folds  occur  in  the  vicinity  of 
Machuca.  The  same  evidence  of  faulting  and 
folding  would  probably  be  found  elsewhere  if 
the  exposures  were  sufficiently  abundant  to  ren- 
der the  structure  determinable. 

The  rocks  of  the  Machuca  formation  are  gen- 
erally found  deeply  weathered.  The  weather- 
ing is  hastened  by  the  igneous  constituents 
which  they  contain,  and  the  final  product  is  a 
residual  red  clay  which  is  indistinguishable  from 
the  product  of  the  decay  of  igneous  rocks.  Ex- 
cept for  the  fresh  rock  obtained  beneath  the 
residual  mantle  by  means  of  the  diamond  drill, 
it  would  have  been  impossible  to  determine  even 
approximately  the  limits  of  the  sedimentary  and 
igneous  rocks.  At  some  points,  as  at  Machuca, 
the  sandstone  contains  a  very  large  pro|X)rtion 
of  iron  pyrites  which  by  oxidation  also  tend  to 
hasten  its  decay. 

Nearly  everywhere  the  beds  are  intersected 
by  numerous  joint  planes,  the  only  marked  ex- 
ception being  the  rather  massive  interbedded 
sandstones  exposed  on  Machuca  creek.  Weath- 
ering has  proceeded  inward  from  the  joints  to- 
ward the  centers  of  the  rhomboidal  blocks  pro- 
ducing concentric  shells  about  a  central  nucleus 
exactly  as  in  the  Brito  formation. 

Utilization, — The  beds  of  massive  sandstone 
exposed  on  Machuca  creek,  being  to  a  large  ex- 
tent free  from  joints,  could  probably  be  quarried 
for    dimensional    building    stone.      This    stone 


APPENDIX  II.— GEOLOGIC  REPORT 


119 


would  be  easily  worked  and  fairly  durable.  The 
chief  difficulty  in  quarrying  would  be  the  ex- 
tent of  the  stripping  required  which  would 
doubtless  be  considerable.  These  are  the  only 
beds  known  in  the  region  east  of  the  lake  from 
which  dimensional  stone  could  be  obtained. 

Age  of  the  Formation, — No  fossils  have  as 
yet  been  found  in  the  Maehuca  formation  which 
are  sufficiently  well  preserv^ed  for  specific  deter- 
mination. At  Cruzita,  one  mile  below  Ma- 
ehuca, the  core  from  the  diamond  drill  hole  in 
the  bed  of  the  river  contains  numerous  indis- 
tinct organic  forms.  The  rock  is  described  by 
Dr.  Ransome  as  an  andesitic  tuff  containing 
fragments  of  limestone.  The  organic  forms  are 
revealed  by  the  weathering  of  the  rock  with  the 
removal  of  the  soluble  limestone,  and  they  are 
also  shown  in  the  thin  section  under  the  micro- 
scope. While  they  cannot  be  identified,  they 
strongly  suggest  the  forms  which  occur  so  abund- 
antly in  portions  of  the  Brito  formation.  The 
beds  in  which  they  occur  are  evidently  derived 
in  large  part  from  fresh  volcanic  tuff,  though 
the  latter  was  not  so  abundant  as  to  prevent  the 
growth  of  organisms  in  the  sea  in  which  it  was 
being  deposited.  In  the  absence  of  conclusive 
fossil  evidence,  therefore,  the  age  of  the  Ma- 
ehuca formation,  so  far  as  it  may  be  determined, 
rests  upon  other  and  less  satisfactory  evidence. 
It  is  believed  to  be  nearly  or  quite  contempora- 
neous with  the  Brito  formation,  that  is,01igocene 
(Tertiary).  The  grounds  on  which  this  con- 
clusion is  based  are  briefly  as  follows:  (1) 
There  is  a  general  similarity  in  lithologic  compo- 
sition and  appearance  between  the  two  forma- 
tions. (2)  Both  have  suffered  about  the  same 
amount  of  deformation,  elevation  and  erosion 
since  they  were  deposited.  The  value  of  this 
fact  for  correlation  depends  upon  the  proximity 
of  the  areas  which  they  occupy  and  the  evi- 


dence that  the  recent  geologic  conditions  have 
been  similar  in  both.  (3)  Both  formations  bear 
about  the  same  relation  to  a  group  of  igneous 
rocks  which  was  in  part  contemporary  with  them 
and  in  part  subsequently  invaded  their  beds. 
The  differences  in  composition  of  these  intrusive 
rocks  are  not  gi'eater  than  differences  in  igneous 
rocks  within  the  same  area  which  are  known  to 
be  nearly  or  quite  contemporaneous.  (4)  Fi- 
nally, as  pointed  out  above,  it  is  possible  and 
even  probable  that  the  two  formations  are  nearly 
or  quite  continuous  through  the  southern  part 
of  the  upper  San  Juan  valley. 

In  the  vicinity  of  the  Toro  rapids,  some  dis- 
tance westward  from  the  present  limit  of  the 
Maehuca  formation,  a  few  siliceous  boulders 
have  been  found  which  contain  fossil  remains. 
The  original  location  of  the  beds  from  which 
these  boulders  are  derived  is  not  known,  though 
they  have  probably  not  been  transported  a  great 
distance.  These  fossils  are  unfortunately  only 
casts.  Thev  have  been  examined  bv  Dr.  Dall 
who  savs  thev  "  are  not  determinable,  but  have 
the  general  look  of  a  fresh-water  assembly.'' 
They  are  not  regarded,  however,  as  having  any 
special  bearing  upon  the  age  of  the  Maehuca 
since  it  is  by  no  means  certain  that  they  have 
been  derived  from  that  formation. 

Tertiary  Igneous  Kocks.' — As  stated  above, 
the  beds  of  the  Maehuca  fonnation  occupy  a 
broad  belt  which  crosses  the  valley  of  the  San 
Juan  extending  from  a  point  a  little  below  Cas- 
tillo eastward  gome  distance  beyond  Maehuca. 
While  this  formation  contains  a  considerable 
proportion  of  volcanic  material  and  is  intersected 
by  numerous  dikes,  it  contains  no  lava  flows  and 


>The  writer  is  indebted  to  Dr.  F.  L.  Ransome,  of  the 
U.  S.  Geological  Survey,  for  a  petrographic  examination  of 
the  igneous  rocks  collected  in  Nicaragua,  and  for  the  deter- 
mination of  the  rock  species.  Dr.  Ransome's  petrographic 
notes  are  appended  to  this  report  as  Part  III. 


120 


NICARAGUA   CANAL  COMMISSION 


no  beds,  the  constituents  of  which  are  exclu- 
sively of  volcanic  origin.  In  the  remainder  of 
the  countrv  between  the  lake  and  the  Caribbean, 
wherever  the  underlying  rocks  or  their  residual 
products  rise  above  the  'recent  alluvium  of  the 
flood-plains,  the  rocks  are  almost  entirely  of  vol- 
canic origin.  They  present  a  great  variety  in 
structure  and  appearance,  varying  through  the 
extreme  types  of  volcanic  products  from  dis- 
tinctly stratified  beds  of  fine  volcanic  ash, 
through  well-rounded  conglomerates,  fine  and 
coarse  angular  breccias,  surface  lava  flows  and 
intrusive  masses  of  rather  coarsely  holocrystal- 
line  rock  which  did  not  reach  the  surface  be- 
fore cooling. 

!Massive  Igneous  Rocks. — The  principal  va- 
rieties of  igneous  rocks  which  are  found  between 
the  lake  and  the  Caribbean  are  augite  andesite, 
olivine  basalt,  hypersthene  basalt  and  dacite.  Of 
these  four  varieties  the  first  three  are  very  simi- 
lar in  appearance.  They  belong  to  the  class 
commonly  designated  as  trap  rocks.     They  are 

• 

dark  bluish-gray  to  black  in  color;  generally 
fine-grained  but  often  containing  certain  min- 
erals as  olivine  and  feldspar  which  can  be  read- 
ily distinguished  Avith  the  unaided  eye.  They 
are  generally  compact  and  heavy,  though  a  well- 
marked  vesicular  structure  characterizes  some 
portions  of  the  basalt.  The  red  clay  which  is 
the  final  product  of  their  decay  contains  numer- 
ous residual  boulders  of  the  fresh  rock  covered 
wdth  a  thin  ocherous  crust. 

The  dacite  is  light  gray  in  color  and  is  made 
up  of  abundant  quartz  and  feldspar  crystals  em- 
bedded in  a  fine-grained  or  glassy,  gray  ground- 
mass.  It  is  lighter  than  the  trap  rocks  and  is 
considerably  softer,  even  when  entirely  unweath- 
ered.  The  dacite  contains  numerous  fragments 
of  darker  basic  rocks.  It  doubtless  reached  its 
present  position  as  a  lava  flow,  and  these  inclu- 


sions are  fragments  of  the  underlying  rock 
which  were  picked  up  and  incorporated  in  the 
molten  mass  during  its  passage  through  the 
lower  formations  to  the  surface.  Many  of  them 
are  a  soft  greenish  rock  exactly  like  the  tuff  on 
which  the  dacite  rests.  The  presence  of  these 
included  fragments  of  a  different  rock  is  doubt- 
less the  reason  the  dacite  was  called  conglomer- 
ate in  the  Canal  Company's  Eastern  Divide  sec- 
tions. Of  the  fragmental  igneous  rocks  two 
classes  may  be  made,  according  as  their  igneous 
or  sedimentary  characteristics  are  the  more 
prominent.  In  the  first  class  are  included  the 
tuffs  which  form  the  western  portion  of  the 
Eastern  Divide,  passing  under  the  dacite  at  an 
angle  of  about  5°.  This  tuff  is  related  to  a 
basic  lava  either  andesite  or  basalt.  It  has  a 
dark  greenish  color  and  very  fine  grain.  It  is 
soft  and  talcose,  and  on  exposure  to  the  air  the 
cores  generally  crumble  into  small  fragments. 
While  this  tuff  owes  its  kaolin-like  character  to 
the  decomposition  of  a  basic  glass,  it  was  prob- 
ably never  a  hard  rock.  The  pressure  to  which 
it  has  been  subjected  since  its  deposition  has  apn 
parently  not  been  sufiicient  to  produce  complete 
induration. 

The  extent  to  which  these  rocks  have  weath- 
ered has  been  already  pointed  out,  but  may  be 
referred  to  again  in  explanation  of  the  difficulty 
which  has  been  experienced  in  determining  the 
relations  of  the  various  members  of  the  volcanic 
formations.  All  weather  to  a  red  clay,  and  ex- 
posures which  afford  any  indication  of  the  origi- 
nal character  of  the  underlying  rock  are  ex- 
tremely infrequent.  The  chief  reliance  must 
be  placed  upon  the  occasional  residual  boulders, 
upon  the  presence  or  absence  of  quartz  grains 
in  the  clay  and  upon  the  occassional  cut  banks 
along  the  streams.  The  large-scale  sections  of 
the  proposed  dam  sites  which  are  published  with 


APPENDIX  II.— GEOLOGIC  REPORT 


121 


this  report,  indicate  the  complexity  of  the  rela- 
tions between  the  various  volcanic  formations, 
and  the  hopelessness  of  attempting  to  work  out 
these  relations  from  surface  indications  alone, 
without  tlie  aid  of  sections  derived  from  drilling. 
For  the  reasons  given  above  it  is  practically  im- 
possible to  map  the  surface  outcrops  of  these  va- 
rious rock  varieties.  Their  distribution  can  only 
be  indicated  in  a  general  way. 

The  rock  forming  tlie  hill  on  which  San  Car- 
los is  located  consists  of  augite  andesite.  This 
extends  eastward  down  the  river  to  the  Rio 
Melchorita  forming  the  hills  which  rise  above 
the  level  alluvial  plains.  At  Palo  de  Arco  oc- 
curs olivine  basalt,  and  this  rock  continues  east- 
ward a  short  distiince  bevond  Castillo.  At  the 
Savalos  it  presents  an  amygdaloidal  phase,  and  in 
the  hill  near  the  mouth  of  the  Santa  Cruz  it  con- 
sists of  a  veiy  coarse  breccia.  The  high  hills  at 
the  junction  of  the  San  Carlos  with  the  San 
Juan  consist  of  hyperstheno  basalt  This  is  a 
holocrj'stalline  rock  and  one  which  probably 
cooled  at  some  distance  below  the  surface.  It 
may  possibly  mark  the  center  of  eruption  from 
which  lavas  in  the  surrounding  region,  which 
have  a  similar  composition  but  less  perfect  crj^s- 
talline  structure,  were  derived.  A  similar  but 
less  crystalline  rock  also  occurs  in  the  hills  on 
the  north  side  of  the  San  Juan  river.  To  the 
eastward  at  Oclioa  the  hyperethene  basalt  occurs 
south  of  the  river,  while  the  rocks  at  the  river 
bank  on  both  sides  and  extending  to  the  north- 
ward are  olivine  basalts.  This  olivine  basalt  ex- 
tends eastward  bevond  the  San  Francisco  hills. 

t' 

At  the  Tambor  Grande  it  is  replaced  for  a  short 
distance  by  dacite,  then  in  the  Tamborcito  hills 
by  hypersthene  basalt,  but  again  comes  in  in  the 
Sarapiqui  hills  and  thence  extends  eastward 
forming  all  of  the  hills  which  border  the  lower 
portion  of  the  San  Juan  river  and  also  those 


about  Silico  lake.  The  dacite,  while  it  does  not 
reach  the  surface  at  Ochoa,  was  encountered 
there  in  boring.  It  was  also  found  at  lower 
Ochoa  beneath  a  bed  of  volcanic  tuff  or  breccia 
and  some  unconsolidated  sediments.  It  comes 
to  the  surface  at  Tambor  Grande  and  is  probably 
continuous  northward  in  the  high  ridge  connect- 
ing the  Tambor  Grande  hills  with  the  Eastern 
Divide.  It  forms  the  surface  through  the 
higher  portion  of  the  Eastern  Divide  overlying 
andesitic  tuffs  and  passing  under  basalt. 

Fragmental  Igneous  Rocks. — Since  the 
closely  related  fragmental  rocks,  both  the  bed- 
ded tuffs  and  the  conglomerates,  do  not  weather 
in  such  a  way  as  to  furnish  residual  boulders, 
their  presence  is  much  more  difficult  to  detect. 
From  the  character  of  the  exposures  in  the  bluffs 
along  the  San  Juan  river,  and  from  the  results 
of  the  drill  sections,  it  seems  probable,  however, 
that  the  bulk  of  these  fragmental  rocks  is  as 
great  or  greater  than  that  of  the  massive  rocks. 
About  four  miles  above  the  Boca  San  Carlos 
these  beds  are  exposed  in  a  high  bluff  on  the 
north  bank  of  the  river.  There  is  shown  a  con- 
siderable diversity  in  the  character  of  the  ma- 
terial, varying  from  the  finest  tuff  to  coarse 
rounded  conglomerate.  All  parts  of  the  beds 
are  equally  weathered,  forming  a  tough  clay 
quite  free  from  grit.  The  different  beds  vary 
considerably  in  color,  although  the  prevailing 
colors  consist  of  various  shades  of  red  and  brown. 
The  planes  of  stratification  between  the  differ- 
ent beds  are  not  sharply  marked,  and  the  indi- 
cations are  that  the  deposit  was  made  rather 
rapidly  and  in  the  presence  of  strong  currents. 
Similar  exposures  of  thoroughly  decayed  sedi- 
mentary beds  occur  in  the  river  bluffs  at  various 
points  between  Ochoa  and  the  mouth  of  the  San 
Francisco. 

It  is  probable  that  during  the  extrusion  of  the 


122 


NICARAGUA   CANAL  COMMISSION 


volcanic  rocks  in  this  rcpon  numerous  hodies  of 
water  were  formed  by  the  interruption  of  drain- 
age lines  by  the  lava  flows.  In  these  bodies  of 
standing  water  the  finer  tuffs  were  accumulated 
with  considerable  regularity  in  their  planes  of 
stratification.  Forests  were  present  on  the  ad- 
joining shores  and  much  vegetable^  matter  was 
accumulated  along  vdth  these  silts.  There  thus 
resulted  deposits  of  considerable  <l(»])th  such  as 
those  encountered  at  lower  Ochoa  (see  Fig.  G, 
Plate  XVTI).  These  were  subsequently  covered 
by  lavas  or  deposits  of  f ragmen tal  material  but 
have  never  been  buried  sufficiently  deep  to  bring 
about  their  complete  consolidation.  In  some 
places  conditions  were  favorable  for  the  deposi- 
tion of  calcareous  material.  In  the  section  at  the 
San  Francisco  a  bed  of  very  fine-grained  (»arthy 
limestone  about  three  feet  in  thickness  was  en- 
countered with  fine  volcanic  tuff  al)Ove  and  be- 
low. The  limestone  was  ])erhaps  originally  a 
calcareous  mud  which  has  lx»en  thoroughly  solidi- 
fied and  is  now  comparatively  hard.  The  adja- 
cent tuffs  both  above  and  below  may  have  been 
solidified  at  one  time  but  are  now  soft  and  tal- 
cose.  No  traces  of  organisms  can  be  detected 
in  this  limestone,  and  it  may  have  been  precipi- 
tated from  solution  without  the  intervention  of 
life.  In  the  railroad  cut  near  Silico  lake  there 
occurs  a  bed  of  clay  enclosing  water-worn  peb- 
bles and  numerous  fragments  of  wood  which  is 
immediately  overlain  by  a  flow  of  basaltic  lava. 
This  clay  was  doubtless  alluvial  or  accumulated 
in  a  lake  and  has  probably  not  been  buried  to  a 
sufficient  depth  to  produce  consolidation. 

The  beds  of  lava  and  volcanic  tuff  above  des- 
cribed have  been  but  little  changed  from  the  po- 
sition in  which  they  were  originally  deposited. 
Wherever  bedding  planes  can  be  detected  in  the 
stratified  tuffs,  they  are  practically  horizontal. 
The  planes  separating  lava  flows  generally  have 


a  decided  original  inclination,  and  this  may  be 
increased  or  diminished  by  subsequent  tilting. 
In  the  sections  of  the  upper  and  lower  Ochoa 
dam  sites  (Figs.  5  and  fi,  and  Plate  XVII)  the 
planes  separating  the  several  formations  have  a 
slight  dip  to  the  northeast.  The  same  thing  is 
observed  in  the  sections  of  the  San  Francisco 
embankment  line  and  of  the  Eastern  Divide 
(Figs.  1  to  4  and  0,  and  Plate  XVIII).  Inso- 
far as  these  dips  are  due  to  deformation,  they 
suggest  the  ])resence  of  a  low  anticline  to  the 
east  of  the  Machuca  basin,  its  axis  approxi- 
mately parallel  with  the  Caribbean  coast  and 
crossing  the  San  Juan  near  the  Boca  San  Carlos. 
For  reasons  given  above,  the  structure  of  these 
igneous  fonnations  as  well  as  of  the  Machuca 
sandstone  shown  on  the  geological  sections,  Plate 
XVI,  rests  on  a  verv  few  observations  and 
should  not  be  accepted  with  too  great  confidence. 
TiKCENT  Alluvial  Formations. — The  post- 
Tertiary  formations  of  the  region  include  the 
recent  deposits  which  make  up  the  flood-plains 
of  the  rivers  and  the  delta  plains  about  their 
mouths,  together  with  the  products  of  the  recent 
volcanic  activitv. 

ft 

The  character  of  the  alluvium  has  been  some- 
what fully  described  in  a  previous  section  of  this 
report  and  requires  but  little  further  mention. 
It  varies  in  character  with  the  local  conditions 
imder  which  it  is  deposited  and  with  the  char- 
acter of  the  rocks  from  which  it  is  derived.  On 
the  west  side,  filling  the  valley  of  the  Rio 
Grande,  it  consists  of  fine  brown  sand  and  clay, 
derived  from  the  decay  chiefly  of  the  sandstones 
of  the  Brito  fcnnation.  In  some  places  it  con- 
tains enough  calcareous  cement,  which  has  been 
deposited  by  infiltration  from  above,  to  give  the 
alluvium  a  fair  degree  of  coherence. 

In  the  vallev  of  the  San  Juan  there  is  con- 
siderablv  wider  diversitv  in  the  character  of  the 


APPENDIX  II.— GEOLOGIC  REPORT 


123 


alluvium.  In  the  upper  portion  of  the  valley 
it  consists  of  fine  blue  clav  interbedded  with 
fine  blue  and  brown  sand.  The  sand  occurs 
chieflv  in  the  river  channel  and  is  the  residuum 
which  the  sluggish  current  of  the  river  has  been 
unable  to  transport.  It  is  probable  that  but 
little  sand  would  be  encountered  in  the  alluvium 
at  any  considerable  distance  from  the  present 
channel.  In  the  lower  portion  of  the  valley  the 
alluvium  in  the  immediate  vicinitv  of  the  river 
contains  considerable  black  sand,  such  as  it  is  at 
present  transporting  in  gi'cat  volume.  This  oc- 
curs either  disseminated  through  the  finer  silt 
which  is  derived  from  the  decav  of  rocks  in  the 
adjoining  region,  or  it  occurs  as  distinct  layci*s 
interstratified  with  the  clay.  The  presence  of  a 
considerable  proportion  of  sand  in  the  silt  ren- 
ders it  much  firmer  than  when  the  latter  con- 
sists chiefly  of  clay.  The  sand  does  not  extend 
to  any  great  distance  from  the  present  river 
channel,  and  hence  the  silt  becomes  less  stable 
with  increasing  distance  from  the  river.  The 
material  which  fills  the  tributary  valleys,  such 
as  the  Danta,  the  San  Francisco,  the  Cureno  and 
the  Tamborcito,  is  a  fine  silt,  generally  quite 
free  from  grit,  with  a  blue  color,  and  containing 
abundant  fragments  of  wood  and  leaves.  When 
this  material  is  thoroughly  drained  it  becomes 
fairly  compact,  as  shown  in  the  vertical  banks 
of  the  most  of  the  streams,  but  at  some  distance 
from  these  streams,  where  the  drainage  is  im- 
perfect, it  is  quite  soft  to  a  depth  of  25  to  50 
feet.  This  alluvial  silt  or  mud  when  first  ex- 
posed sometimes  has  a  brilliant  blue  color  which 
quickly  changes  to  a  yellowish  brown  on  expo- 
sure to  the  air.  In  some  cases  the  change  in 
color  takes  place  at  the  exposed  surfaces  within 
a  few  minutes  after  the  air  has  access  to  them. 
The  material  forming  the  delta  plain  of  the 
San  Juan  is  similar  to  that  composing  its  flood- 


plains.  The  black  sand  is  carried  out  to  sea  and 
transported  along  the  shore  by  littoral  currents 
and  thrown  up  to  some  distance  above  tide  level 
by  the  waves,  so  that  within  a  belt  two  or  three 
miles  broad  along  the  coast,  the  surface  is  com- 
posed chiefly  of  black  sand  with  a  small  amount 
of  vegetable  mould.  The  fine  silt  increases  in 
thickness  from  a  feather-edge  at  its  outer  margin 
at  a  rate  somewhat  greater  than  the  eastward 
slope  of  the  delta  plain.  It  is  probable  that  the 
delta  has  always  been  fringed  by  a  belt  of  sand 
which  never  rose  more  than  a  few  feet  above 
sea  level.  The  region,  however,  has  been  sink- 
ing while  the  delta  was  forming.  As  the  delta 
grew  by  accretions  of  sand  to  its  outer  margin, 
the  corresponding  growth  upon  its  surface  was 
made  by  the  fine  silt  deposited  from  the  flood 
waters  of  the  rivers.  The  plane  separating  the 
sand  from  the  overlying  silt  thus  appears  to  have 
a  gentle  landward  inclination,  being  slightly 
above  sea  level  at  the  present  coast  and  some 
distance  below  sea  level  toward  its  inner  margin. 
Recent  Volo.vnio  Rocks. — The  vulcanism 
which  gave  rise  to  the  igneous  rocks  associated 
with  the  Tertiary  sediments  appears  to  have  be- 
come entirely  extinct  in  this  region,  and  doubt- 
less a  long  interval  elapsed  in  which  it  was  free 
from  any  manifestations  of  volcanic  activity. 
In  comparatively  recent  times  the  vulcanism 
was  renewed,  and  its  products  form  the  Costa 
Rican  and  Nicaraguan  volcanic  ranges  which 
have  already  been  described.  Its  products  also 
form  the  Jinotepe  plateau  and  the  plain  of  Leon 
which  extend  northwestward  from  the  great 
lakes  to  the  Pacific.  In  mineralogical  composi- 
tion these  recent  volcanic  products  consist  very 
largely  of  hypersthene  andesite.  The  last  erup- 
tion from  Masaya  was  a  basaltic  lava,  and  a 
comparatively  recent  lava  flow  from  Ometepe  is 
also  a  basalt     With  these  two  exceptions  the 


124 


NICARAGUA   CANAL  COMMISSION 


recent  activity  so  far  as  obson-ed  has  given  rise 
only  to  andesitic  lavas  and  tuffs.  The  cone  of 
Ometepe  consists  largely  of  lapilli  with  occa- 
sional interlaminated  lava  flows.  The  lapilli 
consist  in  about  equal  parts  of  black  or  gray 
pumice  and  of  black  glassy  rock  which  has  been 
thoroughly  shattered  and  ground  up  by  explo- 
sive eruptions.  The  tuffs  from  this  volcano 
which  have  been  carried  to  a  considerable  dis- 
tance from  the  center  of  eruption,  chiefly  by 
wind,  are  composed  more  largely  of  tufaceoua 
material.  The  materials  erupted  from  the  other 
volcanic  centers  forming  the  various  peaks  of 
the  Nicaraguan  range  appear  to  be  similar  in 
composition  to  those  found  in  Ometepe.  The 
Jinotepe  plateau  is  composed  largely,  if  not  alto- 
gether, of  volcanic  tuffs  which  probably  reached 
their  present  jjosition  in  the  form  of  a  more  or 
less  fluid  mud.  This  mud  becomes  solidified, 
but  never  sufficiently  so  to  form  hard  rock.  It 
is  quarried  in  many  places  and  used  as  a  build- 
ing stone.  It  can  be  readily  cut  out  with  a 
pick,  but  becomes  somewhat  harder  on  exposure 
to  the  air.  The  rock  fragments  which  consti- 
tuted this  tuff  vary  widely  in  size  from  large 
boulders  several  feet  in  diameter  to  the  finest 
dust.  They  are  all  angular,  and  in  this  respect 
they  differ  from  the  volcanic  conglomerates  as- 
sociated with  the  Tertiary  rocks  of  the  San  Juan 
valley.  A  further  difference  is  the  almost  com- 
plete absence  of  stratification  and  sorting  of  the 
rock  constituents.  This  tuff  appears  to  have 
been  sufficiently  fluid  to  flow  upon  rather  low 
slopes  and  the  present  southward  and  westward 
slopes  of  the  Jinotepe  plateau  are  probably  the 
original  constructional  slopes.  In  the  vicinity 
of  Managua  planes  separating  successive  mud 
flows  intersect  the  rock  and  are  utilized  in 
quarrying.  In  these  quarries  human  tracks 
have  been  found  in  the  rock  where  they  were 


made  while  it  was  still  in  the  form  of  mud. 
They  prove  the  recency  of  the  tuffs  and  indicate 
something  as  to  its  physical  condition  when  first 
deposited.  At  the  margin  of  this  plateau  the 
tuff  is  found  filling  the  valleys  in  the  older  for- 
mations and  smoothing  out  the  former  irregu- 
larities of  the  topography.  In  many  cases  the 
present  streams  have  in  part  re-excavated  the 
old  valleys,  though  not  to  their  original  width. 
The  vertical  cliffs  surrounding  the  caldera 
lakes,  Apoya  and  Masaya,  display  the  underly- 
ing structure  of  this  plateau  near  the  centers 
from  which  its  material  Avas  derived.  These 
cliffs  are  composed  of  alternating  layers  of  tuff 
and  solid  lava  flows.  It  is  impossible  to  say  how 
far  from  the  centers  of  eruptions  these  lava 
flow^s  extend,  but  the  distance  is  probably  not 
very  great.  Near  the  centers  of  eruption  the 
character  of  the  tuff  is  somewhat  different  from 
that  at  greater  distances.  It  is  less  homogene- 
ous in  character  and  frequently  consists  of 
sharply-defined  alternating  tuff  beds  which 
differ  widely  in  appearance.  In  the  bluffs  sur- 
rounding Lake  Apoya  this  is  well  shown.  Nu- 
merous distinct  bands  of  white  pumice  occur 
interbeddcd  with  dark  lapilli  and  fragmental 
rocks,  and  these  in  turn  are  interbedded  with  the 
lava  flows. 

ROCK  DECAY. 

Importance  of  the  Surtect. — One  of  the 
features  which  first  impresses  the  geologist  or 
the  engineer  in  Nicaragua  is  the  extent  to  which 
the  surface  rocks  are  weathered.  This  feature 
is  common  to  all  tropical  regions,  at  least  to 
those  in  which  there  is  an  abundant  rainfall. 
While  the  extent  of  rock  weathering  has  an  im- 
portant bearing  on  the  geology  of  the  country, 
and  thus  a  high  degree  of  scientific  interest,  it 
is  a  fact  of  prime  importance  to  the  engineer  in 


APPENDIX   II.—GEOLOGIC   REPORT 


125 


planning  any  structures  in  this  region.  It  en- 
ters directly  into  the  cost  of  excavation  and  also 
into  the  cost  and  permanence  of  foundations  for 
all  heavy  structures.  The  weathering  of  rocks 
is  effected  by  two  processes  which  should  be 
carefully  discriminated.  These  are  rock  disin- 
tegration and  rock  decay.  By  the  first  a  rock  is 
broken  down  to  smaller  masses  or  even  to  its 
constituent  minerals  without  the  alteration  of 
the  minerals  themselves.  The  most  active 
agents  are  changes  of  temperature  and  the  ex- 
pansion of  interstitial  water  by  freezing.  Hence, 
in  general,  the  activity  of  the  process  varies  with 
latitude  and  in  the  humid  tropics  where  the 
range  in  temperature  change  is  slight,  the  effects 
are  practically  reduced  to  zero.  By  the  second 
process  the  constituent  minerals  themselves  un- 
dergo alteration  and,  as  will  be  more  fully 
pointed  out  below,  the  active  agents  are  the 
acids  derived  from  the  decay  of  organic  matter. 
Hence  this  second  process  varies  inversely  with 
latitude,  being  most  active  in  the  humid  tropics 
and  reduced  to  zero  in  the  arctic  regions. 

It  should  be  noted  that  it  is  the  first  of  these 
processes,  rock  disintegration,  which  is  chiefly 
inimical  to  the  permanence  of  structures  and 
hence  that  their  relative  durability  is  greater  in 
the  tropics  than  in  higher  latitudes. 

CoNDiTioxs  Favoring  Rock  Decay. — It  has 
been  shown  by  various  investigators  that  the 
conditions  most  favorable  to  rapid  rock  decay, 
and  hence  to  the  accumulation  of  an  extensive 
mantle  of  residual  materials,  are  high  tempera- 
ture and  abundant  moisture.  These  conditions 
are  only  indirectly  responsible  for  a  large  part 
of  the  rapid  rock  decay  which  always  accompa- 
nies them.  They  are  also  the  conditions  on 
which  the  rapid  growth  and  decay  of  a  luxuriant 
vegetation  depends,  and  it  is  the  latter  process 
which  is  chiefly  instrumental  in  hastening  the 
process  of  rock  weathering. 


It  is  manifest  that  heat  alone  without  mois- 
ture does  not  give  rise  to  conditions  which  favor 
rock  decay,  for  it  is  a  common  observation  in 
desert  regions  where  the  temperatures  reach  the 
maximum,  that  rocks  are  disintegrated  to  a  lim- 
ited depth  by  the  alternate  expansion  and  con- 
traction due  to  changes  in  temperature,  but  that 
rock  decay  is  practically  absent.  On  the  other 
hand,  abundant  moisture  and  continuous  low 
temperature  do  not  give  conditions  favorable  for 
rock  decav  since  these  conditions  favor  the  ac- 
cumulation  of  ice  and  snow.  Glaciers  are  effec- 
tive instruments  for  transportation  of  rock  debris 
and  to  a  limited  extent  are  efficient  as  eroding 
agents,  but  practically  no  rock  weathering  goes 
on  in  their  presence. 

Even  where  the  moisture  is  abundant  and  the 
temperature  is  sufficiently  high  for  the  growth 
of  an  abundant  vegetation,  unless  the  conditions 
are  also  favorable  for  the  decay  of  that  vegeta- 
tion they  are  not  favorable  for  rock  weathering. 
This  is  seen  in  the  extremely  luxuriant  forests 
of  the  north  Pacific  coast,  where  the  successive 
generations  of  forests  grow  upon  the  remains  of 
their  predecessors.  The  conditions  are  here 
favorable  for  the  preservation  of  vegetable  re- 
mains in  the  form  of  peat,  and  rock  decay  is 
practically  absent.  It  appears,  therefore,  that 
an  essential  condition  for  rapid  rock  decay  is  the 
rapid  decay  of  abundant  vegetable  matter,  and 
this  leads  to  the  conclusion  that  the  most  effi- 
cient factor  in  the  process  is  the  presence  of  the 
complex  organic  acids  which  are  derived  from 
the  decay  of  vegetation. 

Effect  of  Chemical  Coin  position. — The  depth 
to  which  the  rock  decay  has  gone  and  the  char- 
acter  of  the  products  depend  in  a  considerable 
measure  upon  the  chemical  composition  of  the 
rock,  upon  its  original  j?tructure  and  upon  the 
subsequent  alterations  which  it  has  under- 
gone,   such    as    fracturing    in    the    process    of 


126 


NICARAGUA  CANAL  COMMISSION 


consolidation  or  by  subsequent  d^Tiamic  disturb- 
ances. But  few  rocks  are  found  in  this  region 
wliicb  are  not  either  wholly  or  in  large  part  com- 
posed of  material  of  volcanic  origin.  Hence 
their  chemical  composition  does  not  present  so 
wide  a  range  as  is  usually  foimd  among  sedi- 
mentary and  igneous  rocks.  A  few  are  appar- 
ently the  products  of  thermal  springs,  and  the 
composition  of  these  is  perhaps  the  best  suited 
of  any  to  resist  the  process  of  rock  decay.  Ex- 
amples of  rocks  of  this  origin  are  found  in  the 
small  hill  opposite  San  Francisco,  a  short  dis- 
tance east  of  the  lake  and  also  at  CHiorrera  on 
the  Aguas  ^[uei*tas.  These  arc  composed 
chiefly  of  silica  Avhich  is  the  mineral  least  acted 
upon  by  the  processes  to  which  rock  decay 
is  chiefly  due.  The  ifachuca  sandstone,  as  al- 
ready  explained,  contains  a  large  proportion  of 
feldspathic  minerals  as  well  as  iron  sulphide  and 
carbonate  of  lime.  Hence  it  is  peculiarly  sus- 
ceptible to  hydration,  oxidation  and  solution. 
The  igneous  rocks  belong  to  the  basic  and  inter- 
mediate classes  and  hence  contain  a  large  pro- 
portion of  the  lime-soda  feldspars  and  the  ferro- 
magnesium  minerals.  Both  of  these  groups  of 
minerals  are  especially  liable  to  alteration. 
Quartz,  on  the  other  hand,  is  relatively  scarce. 
There  are  in  the  region  no  quartzites  and  argil- 
lites,  the  two  classes  of  rocks  which  are  especi- 
ally indifferent  to  the  action  of  the  weathering 
processes.  Certain  beds  associated  with  the 
lavas  are  composed  of  fine  volcanic^  ash  in  which 
the  constituent  particles  had  never  acquired  a 
crystalline  structure  but  were  entirely  glassy. 
These  are  perhaps  the  most  rapidly  altered  rocks 
in  the  region,  and  wherever  they  have  been  en- 
countered, even  as  in  the  (^astern  division  at  very 
great  deptlis  beneath  the  thick  sheet  of  dacite, 
they  are  found  in  the  form  of  a  soft  soapy  or 
talcose  rock. 


The  rocks  of  the  Brito  formation  contain  a 
much  smaller  proportion  of  igneous  constituents 
than  any  of  those  in  the  eastern  division.  Hence 
they  are  in  a  measure  free  from  this  source  of 
weakness.  They  contain,  however,  a  large  pro- 
portion of  lime  carbonate,  and  in  them  the 
weathering  process  consists  chiefly  in  the  solu- 
tion and  leaching  out  of  this  cementing  material. 
Tn  most  of  these  rocks  the  lime  forms  so  small  a 
pro])ortion  of  the  entire  mass  that  the  bulk  is 
not  diminished  or  the  structure  altered  by  its 
removal.  The  rock  merely  changes  in  color 
from  bluish  gray  to  brown  or  yellow  and  at  the 
same  time  bcM^onies  soft  and  porous. 

Effect  of  Original  Structure. — The  original 

structure  of  manv  of  the  rocks  is  such  as  to 

I. 

facilitate  weathering  to  a  considerable  degree. 
This  is  especially  tnie  of  the  basalts  which  are 
largely  composed  of  surface  lava  flows  and  have 
the  vesicular  structure  which  is  characteristic  of 
such  flows.  In  manv  cases  it  is  observed  that 
the  degree  of  weathering  in  the  case  of  basalts 
varies  directlv  with  the  extent  of  the  vesicular 
structure.  The  up|x*r  and  lower  surfaces  of  the 
flows  which  were  rapidly  cooled  by  contact  with 
the  underlying  rocks  and  by  exposure  to  the 
air,  contain  more  or  less  abundant  gas  bubble-, 
while  their  central  portions  are  relatively  com- 
pact. Tn  such  cases  it  is  foimd  that  the  vesicu- 
lar portions  are  .thoroughly  weathered,  w^hile  the 
interior  compact  portion  contains  large  boulders 
of  fresh  rock  or  continuous  beds  of  the  same. 
The  dacite  which  so  far  as  obsen'ed  never  has 
the  vesicular  structure  of  the  basalt,  does  not 
show  these  striking  differences  in  the  degree  to 
which  its  different  portions  have  weathered. 
The  depth  of  weathering  in  the  volcanic  san<l- 
stones  and  conglomerates  naturally  depends 
largely  upon  the  original  structure  of  their  con- 
stituents   which    shows    considerable    variation. 


APPENDIX  II.— GEOLOGIC  REPORT 


127 


Thus  the  conglomerate  encountered  at  upper 
Ochoa  is  composed  chiefly  of  pebbles  of  com- 
pact fine-grained  basalt  and  is  weathered  only  to 
a  moderate  depth.  A  conglomerate  was  en- 
countered at  lower  Ochoa  similar  to  the  above, 
except  that  its  constituent  pebbles  arc  largely 
composed  of  vesicular  or  pumiceous  basalt.  This 
diflFerence  in  the  composition  of  the  pebbles  is 
accompanied  by  a  corresponding  difference  in 
the  depth  of  weathering  which  has  extended  to 
a  very  great  depth  in  case  of  the  latter  rock. 

Effect  of  Secondary  Structures, — A  third  im- 
portant factor  in  determining  the  depth  to  which 
rock  decay  has  gone  is  the  extent  to  which  tlie 
rocks  have  been  affected  by  dynamic  agencies 
with  the  production  of  secondary  structures, 
puch  as  folds,  faults  and  joint  planes.  Of  these 
effects  jointing  is  perhaps  the  most  important 
It  pervades  all  the  rocks  of  the  region,  both  ig- 
neous and  sedimentary.  The  joints  which  in- 
tersect the  igneous  rocks  are  perhaps  largely 
due  to  shrinkage  on  (.*ooling.  The  regular  pris- 
matic jointing  common  in  basaltic  lava  flows 
has  not  been  observed  in  this  region.  In  its 
stead  is  a  system  of  more  or  less  regular  joints 
which  divides  the  rock  into  large  rliomboidal 
blocks.  The  loss  basic  rocks,  such  as  the  dacite, 
and  the  volcanic  conglomerates  are  nearly  or 
quite  free  from  these  joints,  and  the  manner  in 
which  thev  weather  is  therefore  different  from 
that  of  the  basalt. 

The  sedimentary  formations  are  generally 
very  d(»eply  fractured.     In  these  the  joints  are 

doubtless  due  to  the  action  of  dvnamic  forces 

« 

which,  while  tliey  have  not  greatly  changed  the 
original  position  of  the  beds,  have  been  sufficient 
to  thoroughly  shatter  them  to  great  depths. 
Onlv  a  few  of  the  more  massive  beds  of  sand- 
stone  have  in  some  measure  escaped  this  gen- 
eral fracturing.     Its  effect  is  most  pronounced 


in  the  less  massive  portions  of  the  Brito  forma- 
tion. At  the  surface  the  joints  have  been  en- 
larged by  the  weathering  process,  and  the  rock 
consists  of  a  loose  mass  of  small  fragments. 
This  condition  prevails  to  a  depth  of  more  than 
a  lumdred  feiet  from  the  surface,  as  shown  by 
the  boring  at  La  Flor.  One  effect  of  the  joint- 
ing of  the  rocks  is  to  make  it  nearly  impossible 
to  obtain  a  core  with  the  diamond  drill.  This 
fractured  calcareous  shale  is  the  material  which 
has  been  termed  "  telpetate  "  and  "  cascajo  "  in 
the  reports  of  the  drilling  done  by  the  Canal 
Company.  In  some  cases  it  was  obsen^d  that 
the  cracks  which  intersected  the  rocks  had  sub- 
sequently been  healed  up  by  the  deposition  of 
calcite.  This,  however,  is  not  general  at  ordi- 
narj'  depths. 

A  direct  consequence  of  the  presence  of  these 
cracks  intersecting  the  rocks  is  the  development 
of  secondary  concentric  structures.  The  crackS 
permit  the  percolation  to  great  depths  of  surface 
waters  bearing  the  agents  which  are  most  active 
in  rock  decay.  The  weathering  proceeds  out- 
ward from  these  joints  with  the  production  of 
successive  concentric  lavers  about  a  central  nu- 
cleus.  The  concentric  stnictures  which  have 
already  been  described  were  thus  produced. 

KocK  Decay  in  the  Eastern  Division. — As 
has  been  already  pointed  out  there  is  a  marked 
difference  in  the  distribution  of  the  rainfall  on 
opposite  sides  of  the  isthmus  with  a  corresjx>nd- 
ing  difference  in  the  character  of  the  vegetation 
and  in  the  extent  and  products  of  rock  decay. 
It  will  be  necessary,  therefore,  to  consider  the 
process  and  tlu*  products  in  the  two  divisions  of 
the  isthmus  separately. 

The  eastern  division  is  characterized  bv  a 
heavy  rainfall,  so  distributed  throughout  the 
vear  that  there  is  no  well-marked  dr>'  season. 
Hence  the  surface  soil  is  never  permitted  to  be- 


128 


NICARAGUA  CANAL  COMMISSION 


come  dry,  and  the  forest  litter  is  never  removed 
bv  fires.  The  entire  surface  is  covered  with  a 
dense  mantle  of  vegetation.  This  consists  of  a 
heavy  forest  growth  except  where  the  land  sur- 
face has  been  so  recently  reclaimed  from  swamps 
and  lagoons  that  it  has  not  yet  been  invaded  by 
the  forest,  or  that  its  surface  is  not  sufficiently 
firm  to  support  forest  trees.  Even  where  the 
forest  does  not  extend,  the  smaller  vegetation  is 
extremelv  dense,  and  the  surface  is  even  more 
eflFectually  protected  than  under  the  forest.  It 
may  be  stated  in  general,  however,  that  all  of 
the  land  which  rises  above  the  margins  of  the 
extensive  flood-plains  and  the  silt-filled  valleys, 
that  is,  all  which  is  underlain  by  rocks  older  than 
the  recent  silt,  is  forest-clad.  The  canopy  of 
foliage  formed  by  the  tree  tops  is  so  perfect  that 
much  of  the  light  and  all  of  the  direct  sunlight 
is  intercepted,  hence  the  smaller  vegetation  at 
the  surface  is  not  exceptionally  luxuriant  and 
only  partially  covers  the  surface. 

The  forest  trees  of  this  region  are  nearly  all 
deciduous,  but  the  season  of  shedding  their  foli- 
age is  different  for  different  species ;  hence  there 
is  a  continuous  supply  of  forest  litter  through- 
out the  entire  year,  and  its  decay  not  being 
checked  by  frost  is  a  continuous  process. 

All  rocks  of  this  eastern  division  show  the 
effects  of  weathering  to  great  depth,  not  only 
the  igneous  but  the  sedimentary  rocks  as  well. 
In  the  course  of  the  drilling  operations  which 
were  carried  on  in  this  region,  a  large  amount 
of  data  was  obtained  concerning  the  depth  to 
which  decay  has  gone  in  rocks  of  various  origin 
and  composition,  and  also  the  products  of  the 
weathering.  The  sections  which  were  obtained 
by  means  of  the  drill  arc  so  numerous  that  only 
a  few  typical  examples  have  been  selected  for 
publication  in  detail  in  this  report.  The  infor- 
mation obtained  in  all  is  of  course  embodied  in 


the  various  sections  which  have  been  prepared 
for  the  use  of  the  engineers.  These  sections 
which  appear  in  Plates  VIII  to  XIV  will  be  re- 
ferred to  for  the  purpose  of  illustrating  the 
statements  here  made  concerning  the  process 
and  products  of  rock  decay. 

Products  of  Rock  Decay. — The  final  pro- 
duct of  rock  decay  in  this  region  is  a  red  clay. 
This  represents  the  complete  oxidation  of  all  the 
constituent  minerals  of  the  rock  except  the 
quartz,  and  the  complete  obliteration  of  the 
original  rock  structure.  From  this  extreme  the 
products  of  rock  decay  present  all  possible  gra- 
dations to  the  perfectly  fresh  rock.  While  there 
are  no  sharp  lines  of  demarkation  between  dif- 
ferent phases  of  the  rock  weathering,  the  pro- 
ducts may  be  conveniently,  though  somewhat 
arbitrarily,  separated  into  three  groups,  namely, 
red  clay,  blue  clay  and  soft  rock.  The  first  two 
differ  chiefly  in  the  degree  of  oxidation,  and  the 
second  differs  from  the  third  chieflv  in  the  ex- 
tent  to  which  the  original  structure  of  the  rock 
has  been  obliterated.  The  third  group  itself  is 
not  sharply  separated  from  the  fresh  rock  but 
passes  into  it  in  most  cases  by  imperceptible 
gradations. 

Red  Clay. — As  already  stated,  in  the  eastern 
division  of  the  region  under  discussion,  all  por- 
tions of  the  surface  which  rise  above  the  mar- 
gins of  the  alluvial  flood-plains,  are  covered  with 
this  final  product  of  rock  decay. 

Its  appearance  and  doubtless  also  its  compo- 
sition vary  somewhat  from  place  to  place.  The 
bright  red  is  varied  by  shades  of  yellow,  b^o^vn 
and  occasionally  olive  green,  but  the  prevailing 
tint  is  nevertheless  very  generally  red.  The 
abrupt  change  in  color  between  the  residual 
clay  and  the  adjacent  alluvial  clay  is  very  strik- 
ing. The  latter  is  never  red,  but  is  always  some 
shade  of  gray  or  blue.     The  only  essential  dif- 


APPENDIX  II.— GEOLOGIC  REPORT 


129 


ference  between  the  two  clavs  is  in  the  form  of 
their  iron.  In  the  alhivium  this  is  in  the  fer- 
rous state,  forming  light-colored  compounds. 
In  the  residual  clay  it  is  in  the  ferric  state,  and 
not  only  more  highly  oxidized  but  the  oxide  is 
in  large  measure  dehydrated,  giving  the  bright 
red  color  of  hematite.  The  cause  of  this  differ- 
ence in  the  state  of  oxidation  in  clays  which  ap- 
pear to  be  affected  by  the  same  conditions,  is 
doubtless  the  different  amounts  of  organic  mat- 
ter incorporated  Avith  them.  As  already  des- 
cribed, the  residual  clay  is  very  compact.  ,  It  is 
never  loosened  by  frost  or  by  shrinkage  cracks. 
The  only  means  by  which  vegetable  matter 
finds  its  way  below  the  surface  is  by  growing 
roots  and  insect  burrows.  The  amount  thus  in- 
troduced is  not  sufficient  to  niateriallv  affect  the 
chemical  conditions  within  the  zone  of  rock  de- 
cay. The  vegetable  matter  at  the  surface  is  so 
rapidly  and  thoroughly  oxidized  that  the  or- 
ganic compounds  which  result  from  the  process 
are  not  effective  reducing  agents  when  they  per- 
colate downward  in  contact  with  the  red  clav, 
but  probably  carry  an  excess  of  oxygen  which  is 
expended  in  the  oxidation  of  the  rock  constitu- 
ents below.  In  the  alluvium,  on  the  other 
hand,  the  vegetable  matter  while  only  rarely 
constituting  a  large  proportion  of  the  mass,  is 
thoroughly  disseminated  through  it  and  con- 
trols the  chemical  conditions,  preventing  the 
oxidation  of  ferrous  compounds  and  reducing 
X  ferric  compounds  to  the  lower  state  of  oxidation. 
Before  the  deposition  of  the  alluvium  which 
now  fills  the  valleys  of  the  region,  the  bottoms 
of  these  valleys  were  covered  with  residual  clay 
the  same  as  that  now  covering  the  hills.  This 
clay  underlying  the  alluvium  and  subjected  to 
the  constant  downward  percolation  of  the  redu- 
cing solutions  from  the  latter  has  generally, 
though  not  always,  lost  its  red  color.  It  is  often 
9 


found  to  be  mottled  with  blue  patches  where  the 
reducing  solution  has  gained  access  to  the  ferric 
oxide. 

Doubtless  the  proportion  of  silica,  alumina  and 
iron  depends  to  some  extent  on  the  composition 
of  the  rock  from  which  the  clav  was  derived,  but 
this  variation  is  not  sufficient  to  produce  marked 
differences  in  its  appearance  and  pliysical  prop- 
erties. The  depth  of  this  upper  division  is  not 
very  great,  usually  from  ten  to  thirty  feet.  The 
separation  between  the  red  clay  and  the  under- 
lying blue  clay  is  usually  rather  sharp,  although 
in  many  cases  there  is  a  band  of  mottled  clay 
between  the  two. 

Blue  Clay, — This  division  is  usually  some- 
what thicker  than  the  overlying  red  clay. 
While  its  prevailing  color  is  blue,  it  varies  from 
white  to  various  shades  of  yellow  and  brown, 
depending  largely  upon  the  original  composi- 
tion of  the  rock  from  which  it  was  derived.  It 
represents  the  zone  of  complete  rock  decay  and 
disintegration  but  incomplete  oxidation.  The 
blue  color  is  due  not  to  the  presence  of  a  redu- 
cing agent  but  to  the  absence  of  a  sufficient  oxid- 
izing agent  to  convert  the  iron  into  the  higher 
oxides.  It  generally  contains  more  or  less 
abundant  fragments  of  thoroughly  weathered 
rock  which  retain  their  original  structure,  and 
where  it  is  derived  from  basalt  it  usuallv  con- 
tains  numerous  boulders  of  fresh  rock,  the  nu- 
clei about  which  concentric  weathering  has 
taken  place.  The  lower  limit  of  the  blue  clay 
division  is  often  more  indefinite  than  its  upper 
limit.  By  an  increase  in  the  number  and  size 
of  the  rock  fragments,  both  fresh  and  weathered, 
it  passes  into  the  zone  of  soft  rock.  As  will  be 
readily  seen,  the  point  at  which  the  division 
should  be  drawn  is,  to  a  large  extent,  arbitrary, 
since  the  distinction  is  at  best  only  one  of  degree. 

Soft  Bock, — The  red  clay  contains  but  few  of 


130 


NICARAGUA  CANAL  COMMISSION 


the  characteristics  of  the  rock  from  wliich  it  was 
derived,  hence  it  is  fairiy  uniform  throughout 
the  region.  In  the  blue  clay,  also,  the  original 
character  of  the  rock  is  almost  entirely  obliter- 
ated and  it  is  therefore  somewhat  uniform.  In 
case  of  the  soft  rock,  however,  in  so  far  as  it  re- 
tains the  original  structure  of  the  rock  from 
which  it  was  derived,  it  presents  the  same  diver- 
sity as  the  hard  rocks  of  the  region.  In  some  cases 
this  division  is  wanting  and  the  blue  clay  ex- 
tends entirely  down  to  the  fresh  rock.  This  is 
the  case  with  the  Machuca  sandstone  as  shown 
in  the  sections  1  and  2,  Plate  XIV.     In  other 

cases  the  blue  clav  is  thin  or  absent  and  there 

*• 

is  a  great  thickness  of  soft  rock.  This  is  the 
case  with  the  dacite  as  shown  at  Tambor 
Grande  in  sections  1  to  3,  Plate  X. 

The  material  classed  as  soft  rock  represents 
the  zone  of  practically  complete  rock  weathering 
but  of  incomplete  rock  disintegration.  The 
forms  of  the  constituent  minerals  can  usually 
be  made  out  in  rocks  which  were  originally 
coarse-grained.  The  original  structure  is  gen- 
erally well  presei'\"ed.  In  the  vesicular  lavas 
the  gas  cavities  are  nearly  as  perfect  as  in  the 
hard  rock.  In  the  volcanic  conglomerates  and 
breccias  the  distinction  of  matrix  and  inclosed 
pebbles  or  angular  fragments  is  perfectly  sharp. 
Yet  all  the  material  included  in  this  class  can 
be  cnmibled  in  the  Angers. 

The  extensive  beds  of  fine  basaltic  and  andes- 
itic  tuff  which  occur  in  the  Eastern  Divide  and 
elsewhere  are  perhaps  the  most  easily  altered 
rocks  in  the  region.  There  is  some  doubt  as  to 
their  ever  having  been  thoroughly  consolidated, 
and  this  may  account  for  the  depth  to  which 
they  are  weathered.  Wherever  found,  even 
under  a  great  mass  of  compact,  fresh  dacite,  the 
tuffs  are  soft  and  talcose,  resembling  a  very- 
compact,  structureless  clay.     The  principal  al- 


teration which  the  material  appears  to  have  un- 
dergone is  hydration.  It  can  be  easily  cut  with 
a  knife,  and  on  exposure  to  the  air  it  loses 
water  and  is  intersected  bv  numerous  cracks. 
If  thoroughly  dried  and  then  immersed  in  water 
it  immediately  crumbles  to  a  fine,  incoherent 
sand.  This  material  has  not  been  placed  in  the 
class  with  the  soft  rock  although  it  might  prop- 
erlv  be  so  classed.  Since  the  classification 
shown  on  the  sections  was  made  w^ith  a  view  to 
its  practical  application  to  engineering  prob- 
lems, the  upper  limit  of  hard  rock  does  not  gen- 
erally correspond  with  the  limit  of  rock  weather- 
ing from  the  surface  downward.  The  rock 
classed  as  hard  usually  shows  more  or  lees  altera- 
tion of  its  constituent  minerals,  but  not  enough 
to  affect  their  coherence.  While  this  incomplete 
weathering  does  not  materially  affect  the  exca- 
vation of  the  rock,  it  becomes  very  important 
and  should  be  carefullv  considered  when  the 
rock  is  intended  for  use  in  construction.  Rock 
which  appears  to  be  perfectly  fresh  when  first 
removed  from  the  quarry  often  contains  many 
incipient  fractures,  and  these  develop  rapidly  on 
exposure.  It  is  probable,  as  will  be  pointed  out 
later,  that  all  of  the  tuff  and  a  considerable  pro« 
portion  of  the  dacite  in  the  Eastern  Divide  cut 
would  develop  this  weakness  on  exposure  and 
hence  w^ould  be  entirelv  unsuited  for  structural 
purposes. 

Rock  Decay  in  the  Western  Division. — 
Turning  now  to  the  western  division  the  phe-  . 
nomena  of  rock  decay  arc  found  to  be  strikingly 
different,  and,  as  already  pointed  out,  this  prob- 
ably depends  largely  on  climatic  differences 
which  prevail  on  opposite  sides  of  the  isthmus. 
The  most  striking  difference  is  the  almost  com- 
plete absence  of  red  color  in  the  surface  soils. 
This  change  in  color  coincides  so  exactly  witli 
the  change  in  climatic  conditions  that  it  is  diffi- 


APPENDIX  II.— GEOLOGIC  REPORT 


131 


cult  to  escape  the  conclusion  that  the  change  in 
color  is  due  directly  to  climatic  causes.  The 
prevailing  color  in  the  surface  soil  in  the  region 
west  of  the  lake  is  a  bluish-gray,  varying  to 
black.  It  is  sometimes  a  yellowish-gray  and 
very  rarely  red.  One  reason  suggested  for  the 
absence  of  the  complete  oxidation  of  the  surface 
soil  and  the  consequent  red  color  is  the  greater 
amount  of  vegetable  matter  which  becomes  in- 
corporated with  the  upper  layers  of  the  soil. 
As  pointed  out  in  the  discussion  of  the  climate 
it  was  shown  that  the  surface  is  alternately 
baked  and  saturated  with  water.  The  numer- 
ous cracks  which  form  during  the  dry  season 
collect  leaves  and  twigs,  and  when  the  cracks  are 
closed  up  by  the  moistening  of  the  soil  this  vege- 
table matter  is  thoroughly  incorporated  with  the 
clay  to  a  very  considerable  depth.  It  may  be 
that  it  is  present  in  sufficient  quantity  to  com- 
bine with  all  the  oxygen  which  is  carried  down 
by  the  percolating  waters  and  thus  prevent  the 
oxidation  of  the  iron  contained  in  the  underly- 
ing rocks.  This  reducing  action  of  the  con- 
tained vegetable  matter  prevents  the  oxidation 
of  the  iron  contained  in  the  alluvial  silts  in  the 
eastern  division,  and  there  seems  no  reason  why 
it  should  not  be  equally  effective  in  preventing 
oxidation  in  the  residual  clays  in  the  western 
division. 

Another  difference  at  once  noted  is  the  ex- 
tent  to  which  rock  decay  has  extended.  The 
opportimities  for  determining  the  extent  of  rock 
weathering  on  the  west  side  have  not  been  so 
good  as  for  determining  its  extent  in  the  eastern 
division,  and  the  rocks  which  are  there  present 
do  not  aflFord  the  same  variety  in  composition 
and  structure.  Observations  are  confined  prac- 
tically to  two  kinds  of  rock,  namely,  the  igneous 
basic  rock  forming  the  large  area  north  of  the 
Kio  Grande  valley,  and  the  rocks  of  the  Brito 


formation.  The  basic  igneous  rocks  do  not 
differ  essentially  from  those  which  occur  on  the 
east  side,  whei*e  they  are  covered  with  a  great 
depth  of  red  and  blue  clays.  On  the  west  side, 
however,  the  residual  material  covering  them 
consists  of  a  comparatively  thin  layer  of  bluish- 
gray  clay.  It  is  somewhat  doubtful  whether 
the  thinness  of  this  residual  mantle  is  due  to  the 
loss  rapid  decay  of  the  rock  or  to  the  more  rapid 
removal  of  the  products  of  weathering.  Cer- 
tainly the  latter  factor  is  important,  but  the  rate 
of  weathering  may  also  be  very  much  slower, 
under  the  climatic  conditions  which  here  pre- 
vail, than  in  the  eastern  division.  The  blue  clay 
appears  to  constitute  practically  the  only  pro- 
duct of  decay,  and  the  extensive  zone  of  soft 
rock  in  which  the  minerals  are  entirely  altered 
but  in  which  the  original  rock  structure  remains 
is  entirely  wanting. 

The  clay  derived  from  the  decay  of  the  Brito 
formation  is  quite  similar  to  that  derived  from 
the  igneous  rocks,  except  that  it  contains  a 
notable  amount  of  sand  where  it  is  derived  from 
the  more  sandy  portions  of  the  formation. 
Where  derived  from  the  calcareous  shales  it 
forms  a  blue  or  black  tenacious  plastic  clay.  Its 
depth  varies  from  nothing  up  to  ten  or  fifteen 
feet,  depending  upon  the  position  in  which  it 
occurs.  The  greatest  tliickness  is  found  in  the 
level  valleys  where  the  surface  is  practically  at 
base  level  and  where  the  surface  erosion  is  prac- 
tically reduced  to  zero.  Upon  the  steep  hill- 
sides, on  the  other  hand,  the  same  kinds  of  rocks 
are  covered  with  a  very  scanty  layer  of  residual 
soil,  or  it  may  be  entirely  wanting. 

So  far  as  known  there  is  nothing  on  the  west 
side  which  con*esponds  to  the  zone  of  soft  rock 
generally  represented  in  the  sections  from  the 
eastern  division.  Wherever  opportunity  was  af- 
forded for  observing  the  character  of  the  passage 


132 


NICARAGUA  CANAL  COMMISSION 


from  the  overlying  blue  clay  to  the  underlying 
igneous  rocks,  the  transition  wa^  found  to  be 
abrupt  and  the  intennediate  zone  of  weathered 
rock  was  absent. 

Overlying  the  shales  of  the  Brito  formation 
there  is  a  zone  of  weathered  rock  which  corre- 
sponds in  some  measure  with  the  zone  of  soft 
rock  generally  observed  in  the  eastern  division. 
Within  this  zone  the  beds  are  thoroughly  shat- 
tered by  the  presence  of  numerous  joint  planes, 
and  concentric  weathering  has  been  more  or  less 
extensively  developed.  The  mechanical  altera- 
tions which  the  rocks  have  suffered,  however, 
are  much  more  important  and  striking  than  the 
chemical  changes,  hence  in  the  sections  this  is 
called  the  zone  of  disintegrated  rather  than  de- 
cayed rock.  For  the  purposes  of  the  engineer, 
however,  the  distinction  is  not  specially  import- 
ant. As  stated  above,  this  is  the  material  which 
has  been  very  loosely  termed  "  telpetate "  and 
cascajo. 

EARTHQUAKES. 

Relation  of  the  Canal  Route  to  Centers 
OF  Volcanic  Activity. — Most  earthquakes  for 
which  a  cause  can  be  assigned  with  any  degree 
of  probability  are  produced  either  by  an  explo- 
sion at  greater  or  less  depth  below  the  earth's 
surface  or  by  a  dislocation  of  the  earth's  crust 
producing  a  fault.  The  former  class  is  confined 
chiefly  to  volcanic  regions,  and  if  the  explosions 
are  sufficiently  long  continued  they  eventually 
find  a  vent  at  the  surface  and  produce  an  active 
volcanic  eruption.  Earthquakes  produced  by 
faulting  are  also  to  some  extent  characteristic 
of  volcanic  regions,  but  may  occur  remote  from 
any  scene  of  volcanic  activity,  especially  in 
regions  which  are  undergoing  rapid  elevation  or 
depression.  They  are  especially  characteristic 
of    regions    in    which    the    mountain-building 


forces  are  active.  Earthquakes  of  the  latter 
class,  due  to  dislocations  of  the  strata,  are  per- 
haps no  more  liable  to  occur  in  the  vicinity  of 
the  Is  icaraguan  Canal  route  than  elsewhere,  and 
hence  they  do  not  constitute  a  danger  which  is 
peculiar  to  this  region  more  than  to  almost  any 
other  in  which  a  ship  canal  might  be  con- 
structed. Earthquakes  of  the  first  class,  how- 
ever, are  assumed  to  constitute  a  menace  to  the 
permanence  of  the  canal  inasmuch  as  the  region 
is  one  of  considerable  volcanic  activity.  The 
question  of  the  risk  incurred  from  this  source  is 
certainly  one  which  should  be  considered. 

In  the  foregoing  description  of  the  topography 
and  geology  of  the  region  tlie  distribution  of 
modem  volcanic  activity  was  indicated.  It  was 
shown  that,  while  the  Xicaraguan  depression  is 
occupied  to  a  considerable  extent  by  volcanic 
rocks,  these  belong  in  large  measure  to  a  former 
geological  period,  and  the  activity  to  which  they 
owe  their  origin  has  long  since  entirely  ceased. 
It  was  shown  further  that  the  onlv  manifestation 
of  volcanic  activity  in  recent  times  has  been 
along  two  lines  of  vents  which  have  given  rise 
respectively  to  the  Costa  Rican  and  the  Nica- 
raguan  volcanic  ranges.  The  former  terminates 
to  the  northward  in  the  peak  of  Orosi.  This 
volcano  appears  at  present  to  be  entirely  extinct, 
and  there  is  no  authentic  record  or  tradition  of 
its  having  been  in  eruption  since  the  occupation 
of  the  country  by  the  Spaniards.  Button  de- 
scribed it  as  to  all  appearances  a  long  extinct  vol- 
cano; an  old  cone  in  an  advanced  stage  of  degra- 
dation by  weathering  and  showing  no  traces  of 
recent  action.  Squire,'  however,  speaks  of  it 
as  in  a  state  of  constant  activitv,  but  he  does  not 
describe  it  from  personal  observation,  nor  does 
he  give  the  date  of  any  authenticated  eruption. 


»  E.  G.  Squire,   "  The  States  of  Central  America,"  New 
York,  1858,  p.  361. 


APPENDIX  II.— GEOLOGIC  REPORT 


133 


Of  the  numerous  volcanoes  in  the  Costa  Rican 
range  to  the  southeast  of  Orosi  only  one  has 
shown  anv  activity  within  historic  times.  This 
is  Irazu,  near  the  center  of  the  range,  which  was 
last  in  eruption  in  1726.  As  described  by  Hill, 
"  the  entire  crater  occupies  but  a  relatively  small 
portion  of  the  great  moimtain  mass  which  it 
caps  and  is  apparently  a  later  parasitic  summit 
growth  upon  a  much  older  mass." '  It  is  evi- 
dent that  the  eruption  which  gave  rise  to  the 
present  conical  summit  of  Irazu  is  an  expiring 
phase  of  the  activity  which  produced  the  massive 
mountain  range. 

The  Xicaraguan  range  terminates  to  the 
southward  in  the  twin  peaks  of  Madera  and 
Ometepe,  occupying  the  island  of  Ometepe. 
The  interval  between  the  northern  terminus  of 
the  Costa  Rican  range  and  the  southern  termi- 
nus of  the  Xiearaguan  range  is  about  thirty 
miles,  and  between  these  points  passes  the  sailing 
line  of  the  canal  in  Lake  Nicaragua.  Madera 
may  be  regarded  as  extinct.  There  is  no  tra- 
dition of  its  having  shown  activity,  and  its  sum- 
mit has  been  greatly  modified  by  erosion,  indi- 
cating that  there  have  been  no  eruptions  for  a 
very  considerable  time.  Ometepe  is  quiescent. 
It  manifested  a  slight  activity  in  1883  when 
there  was  an  eruption  of  lapilli  with  explosions 
of  moderate  violence.  At  present  the  only  sign 
of  activity  consists  in  numerous  fumeroles  from 
which  steam  and  sulphurous  gases  escape. 
While  no  eniption  of  Ometepe  appears  immi- 
nent, there  is  no  certainty  that  its  activity  has 
entirely  ceased,  although  the  indications  are  that 
it  is  on  the  wane.  Mombacho  has  been  extinct 
for  a  long  time.  Its  last  eruption  was  probably 
one  of  the  explosive  type  and  destroyed  its  con- 


1  Tbe  Geological  History  of  the  Isthmus  of  Panama  and 
Portions  of  Costa  Rica,  by  Robert  T.  Hill,  Bull.  Mus. 
Comp.  ZooL,  Vol.  XXVIII,  1898,  p.  230. 


ical  summit.  Ifasaya  was  in  eruption  in  1858, 
but  the  eruption  was  not  accompanied  by  explo- 
sion, simply  consisting  of  the  welling  up  and 
overflow  of  fluid  basaltic  lava.  Momotombo  at 
the  northern  end  of  Lake  Managua  shows  signs 
of  moderate  activity.  It  is  not  at  present  erupt- 
ing solid  material,  but  throws  off  great  volumes 
of  vapors  which  form  a  black  cloud  over  its  sum- 
mit. Steam  and  other  vapors  are  escaping  from 
several  craters  to  the  northward  of  Momotombo, 
l)ut  from  none  of  them  are  any  lavas  or  lapilli 
being  extruded. 

It  is  thus  seen  that  the  present  activity  of  the 
volcanic  vents  which  form  the  Costa  Kican  and 
Nicaraguan  ranges  belongs  almost  entirely  to 
the  solfataric  stage  which  characterizes  the  ex- 
tinction of  volcanic  activity.     Considering  the 
great  mass  of  material  which  has  been  extruded 
from  these  vents  in  comparatively  recent  geo- 
logic times,  it  is  very  clear  that  the  activity  in 
this  region  is  on  the  wane;  and  while  eruptions 
will  doubtless  occur  in  the  future,  it  can  be  as- 
serted with  a  fair  degree  of  confidence  that  these 
will  be  less  violent  and  occur  at  longer  intervals 
than  in  the  past.     It  is  also  clear  that  the  great- 
est activity  at  present  and  hence  the  source  of 
greatest  danger  in  the  immediate  future  is  not 
in  the  vents  which  terminate  the  volcanic  ranges, 
but  rather  in  the  central  portion  of  those  ranges, 
that  is,  in  central  Costa  Rica  and  in  northern 
Nicaragua.     The    experience    of    many    years 
proves  that  these  regions  which  are  the  centers 
of  greatest  volcanic  activity  are  also  the  centers 
from  which  emanate  most  of  the  earthquakes  felt 
throughout  the  Nicaraguan  depression. 

(^OXSl  DERATIONS         AfFECTING         EARTHQUAKE 

Forecasts. — The  subject  of  earthquakes  in  this 
region  and  their  bearing  upon  the  problem  of 
the  canal  have  been  studied  by  Major  C.  E.  But- 
ton, than  whom  no  one  is  better  qualified  to 


134 


NICARAGUA   CANAL  COMMISSION 


speak  on  tliis  subject.  His  report  accompanies 
the  report  of  the  Nicaragua  Canal  Board  of 
1895,  and  his  discussion  of  some  of  the  princi- 
ples of  earthquakes  in  general  and  their  applica- 
tion to  this  particular  region  are  quoted  below. 
^'  As  regards  earthquakes,  it  is  well  known 
that  they  are  comparatively  frequent,  especially 
in  Costa  Rica  and  Nicaragua,  and  a  few  have 
been  destructive  in  verv  restricted  localities.  It 
is  no  doubt  a  matter  of  great  interest  to  the 
Canal  Company;  for  the  question  at  once  arises 
whether  there  is  not  danger  of  serious  damage 
from  this  cause  to  the  works  of  construction,  and 
of  the  still  more  serious  damage  of  long  suspen- 
sions of  traffic.  In  order  to  reach  some  esti- 
mates of  the  magnitude  of  this  danger,  it  may  be 
well  to  state,  as  briefly  as  possible,  some  general 
considerations  which  must  sen^e  for  a  logical 
basis  of  any  estimate: 

*^(1)  The  forecast  of  earthquakes  contemplates 
probabilities  only  and  not  certainties.  That  one 
will  happen  in  a  particular  region  in  a  specified 
number  of  years  is  a  probability  which  is  great 
or  small  according  to  the  nature  of  the  locality 
and  its  extent.  We  may  view  such  probabilities 
as  having  the  nature  of  risk  analogous  to  those 
of  fire  and  shipwreck,  with  the  following  differ- 
ence: Fires  and  shipwTecks  are  of  such  fre- 
quent occurrence,  and  have  been  so  thoroughly 
investigated  by  insurance  companies,  that  their 
probabilities  under  widely  varying  circumstances 
can  be  estimated  with  great  precision,  and  the 
commercial  value  of  the  risk  accurately  deter- 
mined. Earthquake  risks  have  never  been  so 
investigated,  and  it  is  therefore  impossible  to  as- 
sign specific  numerical  values  to  them.  Never- 
theless it  is  sometimes  practicable  to  show  that 
the  risk  is  so  small  that  it  can  be  left  out  of 
consideration  with  prudence,  though  we  may  not 
be  able  to  assign  its  precise  value. 


"  (2)  In  attempting  to  forecast  the  future  prob- 
abilities of  earthquakes,  we  must  assume  that 
the  future  will  be  like  the  past,  precisely  as  is 
done  in  insurance  probabilities.  We  must  as- 
sume that  where  they  have  been  frequent  and 
violent  they  will  continue  to  be  so,  and  that 
countries  seldom  visited  by  them  in  the  past  will 
be  as  seldom  visited  in  the  future.  There  is  no 
other  possible  basis  of  reasoning. 

*' (3)  Eartl^quakes  originate  at  very  different 
depths  in  the  earth,  rarely,  perhaps  never,  ex- 
ceeding twelve  miles,  and  generally  not  exceed- 
ing three  or  four  miles.  We  know  almost  noth- 
ing of  the  ultimate  nature  of  the  forces  or 
causes  which  generate  them;  but  we  know  con- 
siderable about  the  manner  in  which  thev  are 
propagated  after  they  have  been  started,  and 
concerning  their  subsequent  action  and  effects. 
Whatever  may  be  the  causes,  we  must  assume 
that  the  subterranean  tract  or  seat  in  w^liich  they 
originate  occupies  some  space  of  very  limited 
extent  and  contains  some  point  which  may  be  re- 
garded as  its  center — commonly  called  the  cen- 
trum. From  the  seat  of  origin  the  impulses 
are  propagated  as  elastic  waves  in  every  direc- 
tion, in  a  manner  having  much  in  common  with 
waves  of  sound  in  the  air. 

"  (4)  The  intensity  or  violence  of  these  waves 
diminishes  like  that  of  the  air,  at  as  rapid  a  rate 
as  they  are  propagated.  At  any  given  spot  the 
intensity  is  inversely  proportional  to  the  square 
of  the  distance  from  the  centrum. 

"  (5)  In  all  destructive  earthquakes,  the  extent 
of  the  country  in  which  they  are  destructive  is 
but  a  small  fraction  of  the  total  area  throughout 
which  the  tremors  are  perceptible.  Ordinarily 
it  is  not  far  from  the  four-hundredth  part  of  the 
area  perceptibly  shaken.  The  area  in  which  the 
shocks  may  cause  damage  varying  from  slight 
to  serious  (but  not  demolition  or  what  are  usu- 


APPENDIX  II.— GEOLOGIC  REPORT 


135 


ally  considered  destructive  eflFects)  is  commonly 
about  four  to  eight  times  as  large  as  the  destruc- 
tive area,  or  from  the  fiftieth  to  the  one-hun- 
dredth part  of  the  area  of  perceptible  vibration. 
Those  ratios  are  only  roughly  approximate,  and 
they  are  subject  to  some  qualification,  ordinarily 
not  large,  dependent  on  the  depth  of  the  cen- 
trum. They  are  of  importance  as  showing  the 
comparatively  narrow  localization  of  destructive 
and  even  damaging  effects.  Still,  the  destruc- 
tive areas  may  in  some  cases  be  absolutely  con- 
siderable, being  proportional  to  the  total  energy 
of  the  shock  at  the  centrum.  The  destructive 
area  of  the  Charleston  quake  had  a  radius  of  not 
far  from  forty  miles,  but  its  tremors  were  per- 
ceptible at  a  distance  of  700  to  1000  miles.  Its 
great  extent,  as  well  as  the  distances  at  which 
its  tremors  were  felt,  cause  it  to  rank  among  the 
most  powerful  shakes  of  the  present  century. 
Its  intensity  at  the  surface,  however,  while  for- 
midable, was  not  so  excessive  as  has  been  ex- 
perienced in  some  other  memorable  earthquakes. 
This  was  because  its  depth  was  extreme,  being 
in  all  probability  one  of  the  most  deeply  seated 
of  which  we  have  sufficient  knowledge  to  form 
an  opinion.  In  striking  contrast  was  the  Casa- 
micciola  earthquake,  on  the  island  of  Ischia  in 
the  Bay  of  Naples,  in  1884.  Here  the  destruc- 
tive area  had  a  radius  of  less  than  two  miles,  but 
within  that  area  the  violence  was  superlative  and 
the  havoc  great.  At  Naples,  twenty-five  or 
thirty  miles  away,  the  shock  was  only  a  faint 
tremor.  The  depth  of  the  Charleston  quake  is 
computed  at  about  twelve  miles,  with  a  verv' 
moderate  probable  error.  The  Casamicciola 
quake  had  its  origin  at  a  depth,  probably,  of  less 
than  half  a  mile.  Immediately  over  the  cen- 
trum its  intensity  was  apparently  quite  equal  to 
that  in  the  central  area  of  the  Charleston,  but 
the  total  energy  of  the  shocks  w^as  hardly  one 


seven-hundredth  ])art  as  great.  These  two  ex- 
treme instances  may  illustrate  the  varv'ing  effects 
of  total  energy  and  depth  upon  surface  intensity. 
The  comparison  is  analogous  to  one  on  a  smaller 
scale  between  the  explosion  of  one  hundred 
pounds  of  dynamite  at  a  depth  of  one  hundred 
feet  and  thirty  tons  at  a  depth  of  half  a  mile. 
The  effects  at  the  *  epicentrum '  (jx)int  on  the 
surface  vertically  over  the  centrum)  would  not 
differ  much,  but  the  larger  and  deeper  charge 
would  affect  a  vastly  greater  area,  and  would  be 
felt  at  a  much  greater  distance. 

"  There  is  a  tendency  on  the  part  of  all  per- 
sons ^vho  have  not  made  special  study  of  the 
subject  to  entertain  exaggerated  ideas  of  the 
risks  and  dangers  of  what  are  termed  earthquake 
countries.  The  terrors  of  the  ^  epicentral  tract ' 
in  a  great  devastating  series  of  shocks  cannot, 
indeed,  be  exaggerated.  The  error  consists  in 
assuming  them  to  be  frequent,  widespread,  and 
typical  of  the  coimtry.  In  truth,  they  are  rare, 
even  in  the  most  afflicted  region,  and  when  they 
do  come  they  are  destructive  within  relatively 
narrow  limits  only,  while  the  country'  at  large 
is  shaken  only  by  harmless  quivers.  It  is  ex- 
ceedingly rare  for  one  generation  living  on  any 
spot  on  earth  to  have  seen  two  destroying  earth- 
quakes in  the  same  locality.  In  many  volcanic 
countries  there  are  a  few  spots  where  such  catas- 
trophes rei>eat  themselves,  though  usually  after 
very  long  inten-als  of  years.  These  are  known 
and  can  be  shunned  by  the  engineer  and  archi- 
tect, if  need  be.  Apart  from  these,  all  locali- 
ties within  an  earthquake  country'  sufficiently  re- 
moved from  the  known  centers  or  axis  niav  be 

t.' 

regarded  as  being  in  far  less  peril  from  earth- 
quakes than  from  sweeping  destruction  by  an 
uncontrollable  fire. 

"  Briefly,  then,  my  opinion  is  that  the  risk  of 
serious  injury  by  earthquakes  to  the  construe- 


136 


NICARAGUA   CANAL  COMMISSION 


M 


tions  proposed  for  the  Pacific  section  of  the  canal 
is  so  small  that  it  ought  to  be  neglected;  .... 
also,  that  the  risks  to  the  Atlantic  section  are 
still  smaller  than  those  to  the  Pacific  section." 

SsiSBnc  Records  in  the  Cakal  Reoios, — On 
the  29th  of  April,  1898,  there  occnrred  an  earth- 
quake which  was  perceptible  throughout  the 
greater  part  of  tlie  Nicaraguan  depression,  and 
which  was  moderately  destructive  in  the  towns 
of  Leon,  Managua  and  Chinandaga.  A  com- 
mission consisting  of  Dr.  Carlos  Sapper  and  Dr. 
Bnino  Miersch  was  appointed  by  the  Govern- 
ment of  Nicaragua  to  investigate  the  cause  of 
this  earthquake.  This  commission  visited  the 
region  affected  and  made  the  ascent  of  numerous 
volcanic  peaks  in  the  vicinity  of  its  greatest 
violence.  They  found  no  signs  of  imminent 
eruption  in  any  of  the  craters  visited,  and  reached 
the  conclusion  that  the  earthquake  was  due,  not 
to  a  volcanic  explosion  beneath  one  of  the  nu- 
merous craters  of  the  region,  but  to  a  dislocation 
of  the  strata.  It  is  probable,  as  has  been  indi- 
cated in  a  preceding  part  of  this  report,  that  this 
region  to  the  north  of  Lake  Kicaragua  has  been 
affected  by  faults  in  comparatively  recent  times, 
and  the  present  earthquake  may  he  due  to  a 
further  displacement  along  one  of  these  old 
lines  of  fracture  or  to  the  inauguration  of  a  new 
fracture.  The  absence  of  any  signs  of  increased 
activity  in  the  volcanic  craters,  however,  is 
scarcely  conclusive  evidence  that  the  earthquake 
was  not  due  to  a  deep-seated  explosion  intimately 
connected  with  the  causes  of  the  vulcanism.  It 
is  the  deep-seated  explosions,  those  not  relieved 
by  an  eruption  at  the  surface,  which  probably 
cause  tlie  most  destnictive  earthquakes.  "When 
a  vent  is  formed  with  an  open  passage  from  the 
seat  of  the  explosion  to  tlic  surface,  the  violence 
of  the  effects  is  diminished,  or  rather  it  is  mani- 
fested in  an  eruption  of  lapilH  and  lava  rather 


than  in  earthquake  waves  transmitted  through 
the  crust  to  the  surface. 

Leon  was  visited  by  the  writer  shortly  after 
the  earthquake  of  April,  1898.  The  effects  ob- 
seri'ed  in  that  city  were  chiefly  the  formation  of 
eracks  in  the  walls  and  the  partial  destruction  of 
buildings  constructed  of  adobe.  This  material 
has  very  slight  coherence  and  is  poorly  adapted 
to  resist  the  strains  produced  by  earthquake  vi- 
brations. Xo  solidly  built  wooden  or  stone 
buildings  suffered  greater  damage  than  the  for- 
mation of  a  few  cracks  over  the  doors  and  win- 
dows. The  cathedral  of  Leon  suffered  no  dam- 
age except  the  displacement  of  a  large  globe 
which  rested  on  a  slender  support  on  the  orna- 
mental facade  of  the  building.  It  was  con- 
cluded that  if  such  a  structure  as  a  canal  lock 
built  on  a  suitable  foundation,  had  occupied  the 
epicentral  tract  of  the  Leon-Chinandaga  earth- 
quake it  would  have  suffered  no  material  dam- 
age, almost  certainly  not  enough  to  interfere 
with  its  continuous  use.  The  risk  at  points  two 
hundred  miles  distant  from  the  epicentrum,  that 
is  at  the  nearest  point  on  the  canal  route,  would 
have  been  entirely  negligible. 

The  only  source  of  possible  danger  from  earth- 
quakes to  the  eastern  division  of  the  canal  liea 
in  the  Coeta  Rican  volcanoes.  Occasional 
earthquakes  are  experienced  in  central  Costa 
Rica,  the  most  violent  since  the  occupation  of 
the  country  by  the  Spaniards  having  been  the 
one  which  destroyed  the  town  of  Cartego  in 
1841.  This  emanated  from  the  neighboring 
volcano  of  Irazii  and  was  of  the  shallow  type 
with  a  small  epicentral  tract.  It  was  only 
slightly  doatructive  at  San  Jose,  about  thirteen 
miles  farther  from  the  source  than  Cartego. 
The  much  greater  distance  of  the  canal  from 
this  volcano  renders  the  probability  of  an  rarth- 
quakf  from  that  source  extending  its  destruc- 


APPENDIX  IL— GEOLOGIC  REPORT 


137 


tive  area  so  far  as  the  canal  structures  extremely 
small. 

Two  sdurces  of  clanger  to  the  western  division 
of  the  canal  are  present,  in  Orosi  to  the  south 
and  in  Ometepe  to  the  northeast.  As  stated 
above,  there  is  some  doubt  as  to  the  condition  of 
Orosi.  The  probability,  however,  is  that  this 
volcano  is  extinct.  There  arc  no  records  or  tra- 
ditions of  destructive  earthquakes  having  af- 
fected this  region,  although  from  the  absence  of 
large  towns  it  is  doubtful  if  the  absence  of 
records  should  be  considered  as  conclusive  evi- 
dence that  such  earthquakes  have  not  occurred. 
The  distance  of  this  volcano  from  the  nearest 
canal  structures  whicli  would  be  liable  to  injury 
is  so  great  that  unless  the  disturbances  were  of 
exceptional  violence  the  only  effect  at  the  canal 
line  would  be  harmless  earth  tremors.  The  ex- 
tent of  the  danger  from  Ometepe  can  be  some- 
what more  accurately  gaged.  This  volcano  was 
regarded  as  extinct  up  to  the  date  of  its  eruption 
in  1883.  It  was  clothed  with  vegetation  en- 
tirely to  the  summit.  Some  earthquakes  had 
emanated  from  Ometepe  before  the  eruption. 
Squire  speaks  of  the  town  of  Rivas  as  having 
suffered  much  from  earthquakes  previous  to 
1850,  but  gives  no  details  of  their  frequency  or 
violence.  The  one  which  accompanied  the  erup- 
tion of  Ometepe  in  1883  was  only  very  slightly 
destructive  even  at  Rivas,  and  at  the  line  of  the 
canal  its  destructive  violence  had  doubtless  en- 
tirely disappeared.  Even  with  the  intensity 
manifested  at  Rivas  it  would  in  all  probability 
have  been  entirely  harmless  to  such  a  structure 
as  a  canal  lock.  It  is  not  probable  that  those 
which  preceded  that  of  1883  were  much  more 
destructive  or  some  record  of  them  would  have 
been  preserved.  Indeed  the  excellent  state  of 
presentation  in  which  the  ancient  churches  of 
Rivas  and  San  Jorge  are  found  is  conclusive  evi- 


dence that  the  region  has  not  been  visited  by 
earthquakes  of  destructive  violence  for  more 
than  a  century. 

A  consideration  of  the  present  activity  in 
these  two  volcanoes,  therefore,  and  of  the  avail- 
able records  of  earthquakes  in  this  region  would 
seem  to  remove  all  apprehension  concerning  the 
probability  of  damage  to  canal  structures  by 
earthquakes  emanating  from  them.  If  the  dan- 
ger from  these  sources,  which  are  comparatively 
near,  be  considered  so  small  that  it  may  be  dis- 
regarded, that  from  the  more  distant  centers  of 
volcanic  activitv,  both  to  the  north  and  the 
south,  may  be  dismissed  as  altogether  too  small 
to  merit  consideration.  Even  if  there  should 
originate  at  the  present  centers  of  greatest  ac- 
tivity an  earthquake  with  as  great  violence  as 
that  which  has  characterized  some  that  have 
wrought  the  most  destructive  effects  in  Peru  and 
San  Salvador,  it  is  probable  that  the  earth 
waves  would  there  be  so  far  dissipated  before 
reaching  the  line  of  the  canal  that  they  would  be 
comparatively  harmless.  It  therefore  appears  to 
the  writer  that  the  opinion  above  quoted  from 
Major  Button  is  entirely  correct,  namely,  that 
the  risk  of  serious  injury  by  earthquakes  to  the 
constructions  proposed  is  so  small  that  it  ought 
to  be  neglected. 

RECE^'T  GEOLOGIC  HISTORY. 

The  relation  between  the  topography  and  the 
recent  geological  history  of  the  region  is  so  inti- 
mate that  a  description  of  the  former  neces- 
sarily involves  some  statements  concerning  the 
latter.  The  same  is  to  a  somewhat  less  extent 
true  of  the  lithologj\  Hence  in  the  foregoing 
description  of  the  topography  and  of  the  rock 
formations  some  of  the  main  features  of  the 
geological  historj'  have  been  briefly  outlined. 
With  these  prerequisite  facts  of  topography  and 


138 


NICARAGUA   CANAL  COMMISSION 


lithology  the  geological  history  may  now  be 
taken  up  systematically  and  in  some  detail. 

Conditions  Anterior  to  Tertiary  Time. — 
As  already  indicated,  no  rocks  older  than  the 
Tertiary  occur  in  the  region  of  the  Xicaraguan 
depression  so  that  there  is  only  negative  evidence 
as  to  the  conditions  which  prevailed  here  during 
geological  periods  earlier  than  the  Tertiary.  In 
the  region  to  the  northward,  in  Guatemala  and 
northern  Nicaragua,  the  oc»currence  of  granites 
and  crystalline  schists  has  been  described;  also 
small  areas  of  paleozoic  rocks.  The  present 
extent  of  these  older  formations,  however,  as 
well  as  their  former  distribution  is  not  known. 
The  region  to  the  south  in  Costa  Rica  also  con- 
tains older  formations,  but  thev  are  almost  com- 
pletely  covered  by  the  recent  volcanic  rocks  so 
that  the  former  extent  of  the  land  in  this  direc- 
tion also  is  unknown.  It  is  quite  possible  that 
a  depression  of  this  portion  of  the  isthmus  oc- 
curred at  the  beginning  of  Tertiary  time,  and 
that  a  somewhat  extensive  land  area  was  whollv 
submerged  or  converted  into  an  archipelago. 

Early  Tertiary  Deposition  and  Volcanic 
Activity. — As  indicated  in  the  description  of 
the  Brito  and  Machuca  formations  these  rocks 
were  deposited  on  the  sea  bottom  in  early  Ter- 
tiary time.  It  is  assumed  that  during  their 
deposition  there  was  open  communication  be- 
tween the  Atlantic  and  the  Pacific  oceans  across 
this  portion  of  the  isthmus,  although  it  will  be 
readilv  conceded  that  this  conclusion  is  merelv 
an  hypothesis.  Sedimentary  formations  have 
not  as  yet  been  traced  entirely  across  the  isthmus 

and  there  is  no  other  direct  evidence  bv  which 

»■ 

this  hypothesis  can  be  proven.  If,  however, 
there  had  been  any  land  separating  the  two 
oceans,  its  rocks  ought  to  be  recognizable  at  the 
present  time  as  distinctly  older  than  the  Ter- 
tiary sediments  or  the  volcanic  rocks  which  are 


intimately  associated  with  them.  As  already 
stated,  no  such  older  rocks  are  recognized  in  the 
region  of  the  Xicaraguan  depression,  and  al- 
though the  volcanic  activity  which  was  contem- 
poraneous with  the  deposition  of  the  sedimentary 
formations  mav  have  cut  off  the  communication 
l)etw(»en  the  two  oceans  earlv  in  Tertiarv  time, 
it  app<*ars  at  least  probable  that  at  the  beginning 
of  that  period  and  perhaps  through  the  Oligocene 
the  sea  had  free  access  across  the  isthmus. 

The  character  of  the  sedimentarv  rocks  indi- 
cates  in  some  measure  the  conditions  which  pre- 
vailed during  their  deposition,  not  only  in  the 
seas  in  which  thev  were  laid  down,  but  also  in 
the  adjoining  lands.  These  conditions  were 
somewhat  shallow  seas  with  an  abundant  supply 
of  sediment  alternating  between  sand  and  mud. 
The  sediment  appears  to  have  been  chiefly  de- 
rived, not  from  a  region  underlain  by  deeply 
decayed  rocks,  but  rather  from  unconsolidated 
and  recently  ejected  volcanic  material.  The  ex- 
tremely coarse  conglomerates  which  occur  in  the 
Brito  formation  along  the  Pacific  coast  and  on 
the  southwest  shore  of  Lake  Nicaragua  point 
to  the  proximity  of  active  volcanoes.  The 
coarser  material  supplied  by  these  volcanoes 
was  transported  but  a  short  distance  and  shows 
the  effect  of  only  a  moderate  amount  of  wear. 
The  finer  material  was  widely  disseminated  and 
constitutes  a  very  considerable  proportion  of 
the  sedimentarv  formations.  These  contain, 
however,  a  certain  proportion  of  clay  which  was 
doubtless  derived  from  the  residual  mantle  cov- 
ering the  older  rocks  which  formed  adjacent  land 
areas.  The  conditions  at  certain  points  were 
favorable  for  the  deposition  of  limestone.  Con- 
siderable lime  is  disseminated  throughout  the 
entire  Brito  formation  and  is  segregated  in 
marly  beds  and  in  occasional  lenses  of  pure 
limestone.     The  volcanic  activity  not  only  fur- 


APPENDIX  II.— GEOLOGIC  REPORT 


139 


nished  a  large  portion  of  the  material  of  which 
the  sedimentary  rocks  are  composed,  but  it  con- 
tinned  for  some  time  after  their  deposition,  and 
produced  numerous  dikes,  cutting  the  beds  and 
also  the  extensive  lava  flows  which  in  places  rest 
upon  them.  This  volcanic  activity  appears  to 
have  been  much  more  violent  and  long-continued 
near  the  axis  of  the  present  isthmus  than  on  the 
west  side.  The  region  between  Lake  Nica- 
ragua and  the  Pacific  ocean,  as  already  indi- 
cated, is  occupied  chiefly  by  sedimentary  beds 
and  by  recent  volcanic  material.  Only  a  few 
large  areas  and  occasional  dikes  of  intrusive 
rocks  have  been  found  associated  with  the  Brito 
fonnation,  and  it  is  not  certain  that  these  ever 
reached  the  surface.  While  the  coarse  con- 
glomerates along  the  Pacific  coast  demonstrate 
the  near  proximity  of  volcanoes,  the  indications 
are  that  the  volcanic  vents  from  which  this  ma- 
terial was  derived  were  to  the  west  of  the  present 
coast  line.  The  conglomerates  are  confined,  so 
far  as  known,  to  the  immediate  margin  of  tlie 
ocean,  and  the  source  of  the  material  seems 
clearly  to  have  been  to  the  westward.  The  sim- 
ilar conglomerates  which  occur  on  the  south- 
west shore  of  the  lake  appear  to  have  been  de- 
rived from  vents  to  the  southward  and  to  mark 
the  southern  margin  of  the  sea  in  which  the 
Brito  formation  was  deposited. 

As  stated  al)ove,  the  Tertiary  volcanic  ac- 
tivity  was  more  prevalent  in  the  region  east  of 
the  lake.  More  than  two-thirds  of  the  area 
which  has  been  examined  between  the  lake  and 
the  Caribbean  is  now  occupied  by  igneous  rocks 
which  present  considerable  variety  in  compo- 
sition and  structure.  It  is  probable  that  the 
present  area  of  the  ^lachuca  formation  does  not 
represent  its  original  extent,  but  merely  a  region 
in  which  the  volcanic  rocks  have  failed  to  wholly 
conceal  the  sediments.     The  numerous  beds  of 


conglomerate  and  stratified  ash  associated  with 
the  lavas  in  the  region  eastward  from  Machuca 
point  to  the  presence  of  standing  water  during 
the  period  of  volcanic  activity.  This  water  in 
which  the  ejecta  were  deposited  may  have  been 
a  shallow  sea  from  whose  bed  the  volcanoes  rose, 
or  a  series  of  lakes  formed  upon  the  imperfectly 
drained  constructional  surface.  It  is  very  dif- 
ficult, however,  to  determine  even  approximately 
the  conditions  which  prevailed  during  the  depo- 
sition of  this  heterogeneous  collection  of  forma- 
tions. The  difliculty  is,  of  course,  greatly  en- 
hanced by  the  deeply-weathered  condition  in 
which  the  rocks  are  now  found. 

MroDLE  Tektiary  Uplift  and  Erosion. — The 
period  of  deposition  in  this  region  appears  to 
have  been  terminated  toward  middle  Tertiary 
time  by  an  uplift  which  was  coincident  with  a 
suspension  of  the  volcanic  activity.  The  ex- 
tent of  the  land  after  the  uplift  can  only  be  de- 
termined in  a  very  general  way.  It  is  probable 
that  the  Pacific  coast  was  some  distance  farther 
southwest  than  at  present,  and  there  may  have 
been  volcanic  peaks  along  this  coast  which  have 
subsequently  been  entirely  removed  by  marine 
erosion.  The  isthmus  was  very  likely  somewhat 
broader  than  now,  although  the  elevation  was 
such  that  any  particular  rock  stratum  was  from 
one  to  two  hundred  feet  lower  than  at  the  pres- 
ent time.  The  uplift  inaugurated  a  period  of 
active  degradation.  It  is  probable  that  the  sur- 
face at  the  beginning  of  this  period  was,  in  gen- 
eral, broadly  undulating  with  perhaps  isolated 
volcanic  peaks  but  no  distinct  mountain  chain. 
The  uplift  was  accompanied  by  only  moderate 
warping  and  tilting  of  the  surface,  for  the  Ter- 
tiary beds  have  suffered  comparatively  little  dis- 
turbance up  to  the  present  time.  Their  average 
dips  are  between  ten  and  fifteen  degrees.  In 
general,  the  character  of  the  deformation  was 


140 


NICARAGUA   CANAL  COMMISSION 


such  as  to  produce  a  series  of  gentle  folds  whose 
axes  are  approximately  parallel  with  the  coast 
lines.  This  was  doubtless  accompanied  by 
more  or  less  faulting,  although  evidence  of  the 
latter  is  very  meager.  The  character  of  the 
present  drainage  makes  it  evident  that  no  struc- 
tures were  developed  in  the  region  suiRciently 
well-defined  and  pronounced  to  have  a  marked 
influence  on  the  direction  of  the  drainage.  The 
stream  courses,  with  the  exceptions  which  have 
been  already  noted,  and  which  will  be  explained 
later,  are  such  as  would  have  resulted  from  nor- 
mal stream  development  upon  a  low,  gently  un- 
dulating arch. 

The  region  now  occupied  by  the  Xicaraguan 
depression  appears  to  have  been  originally  the 
lowest  and  narrowest  portion  of  the  isthmus; 
hence  its  surface  was  more  nearlv  reduced  to 
base  level  (luring  this  degradation  period  than 
that  of  the  broader  portion  to  the  north.  A 
somewhat  perfect  peneplain  was  developed  along 
its  margins,  and  broad  base-leveled  valleys  were 
extended  well  back  to  the  divide  in  w-hich  there 
were  numerous  low,  broad  gaps.  Although  the 
position  of  the  coast  lines  at  the  beginning  of 
this  period  is  not  easily  determined,  their  posi- 
tion at  its  conclusion  mav  be  made  out  with  a 
fair  degree  of  probability.  The  Atlantic  coast 
was  perhaps  about  where  it  now  is  or  possibly 
a  little  farther  east  than  at  the  present  time,  for 
although  it  has  subsequently  been  moved  west- 
ward by  submergence  and  by  marine  erosion,  it 
has  also  been  considerably  extended  by  emerg- 
ence and  by  deposition,  so  that  its  oscillations 
have  about  balanced  each  other.  The  Pacific 
coast,  on  the  other  hand,  differed  materially  in 
outline  from  the  present.  As  already  indicated. 
Lakes  Nicaragua  and  Managua  then  had  no  ex- 
istence, and  the  coast  line  occupied  a  position 
indicated  by  one  of  the  lines  on  the  accompany- 


ing sketch  map,  Plate  II.  The  second  line  is 
intended  to  represent  the  position  of  the  coast 
at  a  somewhat  later  period. 

Post-Tertiaky  Elev^ation  and  Gorge-Cut- 
ting.— The  middle  and  late  Tertiary  time  as  in- 
dicated  above,  w^as  occupied  by  a  period  of  ero- 
sion with  the  reduction  of  much  of  the  region  to 
the  condition  of  a  peneplain.  In  the  late  Ter- 
tiary or  Pleistocene  the  region  was  again  ele- 
vated, this  time  probably  without  deformation 
of  its  surface,  although  there  may  have  been  a 
slight  arching  of  the  isthmus  on  the  northwest- 
southeast  axis,  and  possibly  also  an  arching  on 
a  subordinate  axis  west  of  the  present  lake  basin. 
The  total  elevation  w-as  probably  between  200 
and  300  feet.  The  immediate  effect  of  this  up- 
lift was  to  stimulate  the  streams  to  renewed 
activity.  They  began  at  once  to  trench  the 
penei)lain  and  the  broad  base-leveled  valleys 
which  they  had  formed  in  the  preceding  period. 
The  effect  of  the  uplift  was  necessarily  first  felt 
in  the  lower  courses  of  the  streams  and  their 
vallevs  were  there  first  lowered  to  the  newlv- 
established  base  level.  Thence  the  deepened 
channels  were  cut  backward  toward  their  head- 

w^aters.     In  the  vallev  of  the  river  which  occu- 

« 

pied  the  present  position  of  the  San  Juan  from 
Castillo  eastward  various  phases  in  the  process 
of  reduction  were  present.  In  the  low^er  course 
of  the  stream  a  broad  valley  was  developed  with 
only  a  few  isolated  remnants  of  the  former  plain 
remaining.  This  extended  upward  as  far  as 
Tambor  Grande.  From  Tambor  Grande  to  the 
Boca  San  Carlos  the  valley  was  rather  broad,  but 
the  adjacent  hills  retain  distinct  evidences  of 
the  former  peneplain,  and  wherever  the  rocks 
w^ere  unusually  hard  the  valley  of  the  stream 
was  correspondingly  restricted.  Between  the 
Boca  San  Carlos  and  the  Continental  Divide, 
which  was  then  near  the  present  position  of  (^as- 


APPENDIX  II.— GEOLOGIC  REPORT 


141 


tillo,  the  stream  was  comparatively  small  and 
flowed  in  a  narrow  gorge.  Its  channel  was  cut 
down  to  a  rather  low  gradient  backward  to  the 
present  position  of  the  Machuca  rapids.  At 
this  point  was  the  junction  of  three  branches, 
probably  of  nearly  equal  size,  occupying  the  val- 
leys of  the  Infiernito,  the  ]N[achuca  and  the 
present  San  Juan. 

The  tributaries  of  this  river  also  cut  down 
into  the  old  valleys,  and  the  extent  to  which  they 
succeeded  in  lowering  their  channels  varied  with 
their  position  and  size.  Xaturally  those  nearest 
the  mouth  of  the  stream  were  earliest  stimulated 
to  renewed  activity  by  the  lowering  of  the  trunk 
stream  into  which  they  flowed,  and  hence  these 
had  the  longest  time  in  which  to  effect  the  low- 
ering of  their  own  channels,  while  those  nearer 
the  headwaters  of  the  trunk  stream  were  not  ma- 
terially  affected  until  late  in  the  gradation 
period.  Thus  the  tributaries  of  the  San  Juan 
as  far  up  as  the  San  Francisco  have  lowered 
their  channels  below  their  old  base  level,  if  not 
entirely  to  their  headwaters,  at  least  well  back 
toward  them.  Beyond  the  San  Francisco  the 
upper  portions  of  the  tributaries  are  found  still 
flowing  at  the  level  of  their  old  valleys,  which 
they  have  not  as  yet  had  time  to  completely  dis- 
sect. Excellent  examples  of  this  immature 
drainage  are  seen  in  the  basin  of  the  Machado 
and  with  increasing  frequency  from  that  point 
westward  to  the  Toro  rapids.  Thus  the  Ma- 
chuca and  Bartola  are  rapid  streams,  still  ac- 
tively corrading  their  channels  almost  down  to 
their  junction  with  the  San  Juan. 

The  stream  which  occupied  the  upper  portion 
of  the  San  Juan  valley,  as  indicated  above, 
headed  upon  the  Continental  Divide  iii  the 
vicinity  of  Castillo,  and  receiving  as  tributaries 
the  Rio  Frio  and  other  streams  now  emptying 
into  the  lower  end  of  the  lake,  flowed  northwest- 


ward to  the  head  of  a  bay  in  the  vicinity  of  the 
island  of  Madera.  This  stream,  like  the  other, 
was  stimulated  by  the  uplift  and  rapidly  cut  its 
channel  backward,  dissecting  its  old  valley  well 
up  toward  the  Continental  Divide.  This  old 
channel,  now  drowned  by  the  waters  of  Lake 
Nicaragua,  has  been  traced  more  or  less  contin- 
uously from  the  vicinity  of  ^Fadera  southeast- 
ward with  gradually  decreasing  depth  to  the 
vicinity  of  the  Balsillas  islands.  It  may  very 
likely  have  extended  beyond  this  point,  and  its 
upper  portion  have  been  subsequently  filled  by 
the  sediment  carried  into  the  southern  end  of  the 
lake,  chiefly  by  the  Rio  Frio. 

The  cape  which  extended  northwestward  be- 
tween the  waters  of  the  Pacific  ocean  and  the 
Bay  of  Nicaragua  appears  to  have  suffered  some 
differential  uplift,  its  southern  portion  being 
elevated  more  than  its  northern  portion.  Not 
enough  study  has  yet  been  given  to  the  whole 
of  this  region,  however,  to  determine  with  any 
degree  of  certainty  the  details  of  its  recent  his- 
tory. Nevertheless  it  is  known  that  the  rivers 
to  the  southward  of  the  Rio  Grande  have  cut 
their  channels  much  deeper  than  those  to  the 
northward  and  that  some  of  the  latter  appear  to 
have  been  affected  but  little  either  by  this  uplift 
or  by  the  subsequent  depression.  Only  the  val- 
ley of  the  Rio  Grande  has  been  carefully  studied, 
and  it  is  certain  that  the  uplift  in  this  region 
was  at  least  200  feet. 

The  active  wave-cutting  along  the  Pacific 
coast  during  this  and  the  preceding  period  short- 
ened the  distance  from  the  coast  to  the  subor- 
dinate divide  on  the  highland  forming  the  cape, 
thus  rendering  the  length  of  the  streams  flowing 
in  opposite  directions  from  this  divide  very  un- 
equal. Those  flowing  to  the  Pacific,  therefore, 
had  a  very  steep  gradient  while  those  flowing 
eastward  to  the  Nicaraguan  depression   had   a 


142 


NICARAGUA  CANAL  COMMISSION 


comparatively  flat  slope.  Hence  the  corrasion 
of  their  channels  was  proportionately  greater  by 
the  streams  flowing  directly  to  the  Pacific  than 
by  those  which  reached  the  ocean  indirectly 
through  the  Bay  of  Nicaragua.  The  former 
group,  of  which  the  stream  occupying  the  lower 
portion  of  the  present  Kio  Grande  valley  is  the 
best  studied  example,  cut  their  valleys  well  down 
toward  the  new  base  level  nearly  up  to  the  di- 
vide; while  the  inner  portion  of  the  peneplain 
occupied  by  the  eastward  flowing  streams  was 
scarcely  at  all  affected,  and  the  gorge-cutting 
was  confined  chiefly  to  their  lower  portions, 
which  are  now  occupied  by  the  waters  of  the 
lake.  It  is  true  the  main  trunk  stream  entering 
the  head  of  the  bay  cut  its  channel  backward 
well  toward  its  headwaters,  but  the  tributaries 
from  the  southwest  cut  only  shallow  trenches 
in  the  outer  portion  of  the  Kivas  plain  and  none 
at  all  in  its  inner  portion.  The  relations  of 
coast  lines  and  divides  which  prevailed  at  this 
period  are  represented  on  the  outline  map,  Plate 
n,  while  the  former  drainage,  together  with  the 
present  drainage  and  relief,  are  shown  on  the 
map  forming  Plate  VI.  The  divide  between 
the  streams  flowing  to  the  Pacific  and  those  flow- 
ing to  the  bay,  which  after  the  bay  had  been 
converted  into  a  lake  became  the  Continental 
Divide,  is  shown  by  the  broken  line  near  the 
Pacific  coast.  The  length  of  the  streams  flow- 
ing in  opposite  directions  from  this  Divide  is 
seen  to  be  very  unequal.  The  inequality  in 
length  is  so  great  that  before  the  acceleration  in 
corrasion  could  be  felt  half-way  up  the  courses 
of  the  longer  eastward  flowing  streams  it  had 
caused  a  deepening  of  the  entire  channels  of  the 
shorter  Pacific  streams.  With  such  advantages 
the  shorter  streams  began  an  active  conquest  of 
drainage  area  from  those  less  favorably  located 
on  the  east  of  the  Divide.     The  result  was  that 


at  one  point  where  the  advantages  of  the  Pacific 
stream  were  most  decided,  the  divide  between 
contending  streams  was  pushed  eastward  and 
successive  portions  of  the  eastern  drainage  were 
diverted  to  the  Pacific.  The  rapidity  with 
which  different  portions  of  the  divide  were 
shifted  eastward  depended  largely  on  its  relative 
height  and  the  length  of  the  contending  streams. 
The  conditions  were  evidentlv  most  favorable 

1 

nearly  opposite  the  end  of  the  bay,  probably  be- 
cause the  soft  sedimentarv  rocks  here  extended 
entirely  across  from  the  ocean  to  the  bay,  while 
to  the  north  and  south  there  were  considerable 
areas  of  harder  igneous  rocks.  Hence  the  sur- 
face had  here  been  well  reduced  in  the  preced- 
ing period  and  was  favorably  circumstanced  for 
further  rapid  reduction.  The  stream  which 
sufferefd  diversion  earliest  appears  to  have  occu- 
pied the  present  position  of  a  portion  of  the 
Tola,  the.  upper  Rio  Grande,  the  Guiscoyol  and 
the  lower  Lajas.  This  stream  was  probably  five 
or  six  times  the  length  of  its  opponent  on  the 
Pacific  side,  so  that  the  same  fall  from  the  di- 
vide was  distributed  over  a  correspondingly 
greater  distance,  and  hence  had  relatively  much 
less  than  a  fifth  of  the  efliciencv  of  the  shorter 
stream.  The  eastward  flowing  stream  had  in 
the  preceding  period  developed  a  rather  broad 
valley,  the  upper  portion  of  which  lay  between 
the  main  divide  and  the  hills  bordering  the  Rivas 
plain.  The  remnants  of  this  base-leveled  valley 
are  found  in  the  upper  Tola  basin,  while  the 
lower  portion  of  that  basin  is  very  perfectly  re- 
duced to  the  present  base  level,  only  the  uniform 
summits  of  a  few  rounded  hills  suggesting  the 
former  existence  of  a  plain  at  a  higher  level. 
In  the  upper  Rio  Grande  basin  the  Rivas  plain 
can  be  traced  from  its  typical  development 
at  the  present  Continental  Divide  westward 
through  the  increasing  degrees  of  dissection  to 


NICARAGUA  CANAL  COMMISSION. 


MAP  TO  ILLUSTRATE  RECENT 


APPENDIX  2,  PLATE  VI. 


G  OF  THE  CONTINENTAL  DIVIDE. 


APPENDIX   H.—GEOLOGIC   REPORT 


143 


the  summits  of  a  few  hills  nearly  down  to  the 
Tola.  The  inference,  therefore,  that  the  rem- 
nants of  the  plain  observed  in  the  upper  Tola 
and  in  the  upper  Kio  Grande  valleys  were  orig- 
inally portions  of  the  same  base-leveled  plain,  is 
fairly  well  established.  Accelerated  by  the  low- 
ering of  its  outlet  the  diverted  Tola  has  itself 
made  considerable  progress  in  the  conquest  of 
drainage  formerly  belonging  to  the  eastward 
flowing  streams.  It  has  diverted  branches  both 
of  the  Gonzales  and  Medio,  the  reversed  streams 
now  forming  the  Chacalapa  and  Matinga,  and 
leaving  low  gaps  in  the  present  Continental  Di- 
vide. The  Guachipilin  now  flowing  into  the 
upper  Rio  Grande,  formerly  found  an  outlet 
eastward  to  the  Medio,  and  its  deserted  valley  is 
the  point  for  crossing  the  divide  selected  by  Com- 
mander Lull  for  his  canal  route.  The  latest 
diversion  has  evidently  been  the  Guiscoyol, 
which  was  perhaps  the  largest  stream  in  this 
region  flowing  eastward.  Its  source,  now 
forming  the  headwaters  of  the  Eio  Grande, 
was  in  the  high  hills  which  border  the  lower 
Rio  Grande  valley.  The  Rio  Grande  is  thus 
seen  to  have  a  composite  course,  which,  con- 
sidering the  Cascabel  as  its  head,  now  makes 
a  nearly  complete  circuit  before  reaching  the 
sea. 

The  recently  deserted  gap  between  the  di- 
verted upper  Rio  Grande  and  the  beheaded 
Guiscovol  is  a  broad  shallow  valley,  its  highest 
point  being  154  feet  above  sea  level.  It  is  oc- 
cupied during  the  wet  season  by  a  swamp  from 
which  the  water  appears  to  flow  in  both  direc- 
tions. That  flowing  toward  the  lake  occupies 
a  shallow  channel  evidentlv  once  the  bed  of  a 
larger  stream,  while  that  flowing  west  soon  finds 
itself  in  a  narrow,  sharply  cut  ravine  with  rapid 
descent  to  the  rather  deep  channel  of  the  Rio 
Grande. 


The  process  of  diversion  above  outlined  was 
inaugurated  at  the  beginning  of  the  high-level 
period  now  being  considered,  but  it  doubtless 
continued  during  the  succeeding  period  after  the 
formation  of  the  lake.  It  is  evident  that  the 
process  is  still  going  on  and  that  the  Continental 
Divide  is  now  moving  eastward  at  a  rate  which 
may  be  regarded  as  extremely  rapid  compared 
with  most  drainage  changes  and,  with  the  de- 
cided advantages  possessed  by  the  Rio  Grande, 
it  is  somewhat  surprising  that  the  latter  stream 
has  not  already  tapped  the  lake. 

Recent  Depression  and  Alluviation. — 
The  process  of  gorge-cutting  which  characterized 
the  period  of  high  level  just  described  was  ter- 
minated by  a  depression  of  the  region,  amount- 
ing to  a  little  more  than  half  the  elevation  which 
had  inaugurated  the  preceding  period.  The 
effect  of  the  depression  was  to  drown  the  lower 
portions  of  the  river  valleys,  converting  them 
into  tidal  estuaries.  At  first  the  depression  af- 
fected only  those  portions  of  the  river  valleys 
which  were  brought  below  sea  level,  while  in 
the  upper  portions  the  deepening  of  the  stream 
channels  continued  as  actively  as  before.  The 
waste  from  the  land,  however,  instead  of  being 
carried  out  to  sea  and  distributed  by  littoral  cur- 
rents began  at  once  to  shoal  and  fill  up  the  heads 
of  the  estuaries.  With  the  consequent  length- 
ening of  the  streams  their  beds  were  raised  and 
consequently  the  influence  of  the  depression  was 
extended  up  their  valleys  at  a  rate  correspond- 
ing to  the  extension  of  their  lower  courses.  It 
is  probable  that  the  depression  of  the  surface  was 
comparatively  slow,  and  the  filling  of  the  estu- 
aries may  have  very  nearly  kept  pace  with  their 
formation.  As  soon,  however,  as  the  depression 
of  the  land  was  at  any  point  slower  than  the 
filling  of  tlie  estuary,  the  influence  of  the  de- 
pression would  proceed  upstream  at  a  rate  de- 


144 


NICARAGUA  CANAL  COMMISSION 


pending  upon  the  extension  of  the  lower  course 
of  the  river. 

The  depression  of  the  land  appears  to  have 
been  accompanied  by  a  moderate  local  warping 
of  the  surface.  This  warping  may  have  affected 
the  entire  isthmus,  but  the  means  of  detecting  it 
are  not  at  hand  except  in  the  western  portion. 
The  Kivas  plain  has  evidently  suffered  a  gentle 
tilt  to  the  northeast  and  it  is  more  than  probable 
that  this  tilting  was  accomplished  during  the 
depression  of  the  land  surface.  It  will  be  re- 
called that  the  Rivas  plain  is  a  plain  of  degra- 
dation formed  by  the  action  of  streams  flowing 
near  base  level.  A  plain  formed  in  this  way 
must  necessarily  be  nearly  horizontal,  but  the 
present  Kivas  plain  has  a  slope  to  the  northeast 
of  about  eight  feet  to  the  mile.  This  is  mani- 
festly greater  than  the  gradient  of  streams  form- 
ing a  base-leveled  plain.  It  is  considerably 
greater  th^n  the  gradient  of  the  present  streams 
which  cross  it.  The  latter,  emerging  from 
rather  deep,  narrow  gorges  in  the  residual  hills 
to  the  southwest,  cut  narrow  channels  in  the 
inner  portion  of  the  Rivas  plain.  These  chan- 
nels in  some  cases  have  a  depth  of  sixty  feet  or 
more.  They  gradually  decrease  in  depth  toward 
the  outer  margin  of  the  plain,  the  unequal  slopes 
of  the  stream  bed  and  the  peneplain  surface 
bringing  them  together  at  the  lake  margin. 

Accompanying  the  depression  of  the  land 
which  inaugurated  this  period  was  a  renewal  of 
the  volcanic  activity  of  the  region.  It  is  pos- 
sible that  the  vulcanism  and  the  depression  may 
be  intimately  related  as  cause  and  effect,  or  may 
be  both  the  effects  of  a  common  cause.  How- 
ever this  may  be  with  regard  to  the  depression 
of  the  region  as  a  whole,  it  is  more  than  prob- 
able that  the  observed  deformation  of  the  sur- 
face is  due  directly  to  the  volcanic  activity. 
This  activity  was  manifested  along  two  lines  of 


vents,  forming  the  lines  of  volcanic  craters  whose 
topography  has  already  been  described.  The 
southern  series  of  vents,  forming  the  Costa 
Rican  volcanic  range,  broke  out  within  a  land 
area  and  possibly  upon  a  somewhat  elevated 
plateau.  These  volcanoes  have  obliterated  the 
pre-existent  topography  and  built  up  a  massive 
mountain  range.  The  northern  series  of  vents 
forms  the  Nicaraguan  volcanic  range.  Between 
the  nearest  peaks  of  the  two  ranges,  Orosi  to 
the  south  and  Madera  to  the  north,  there  is  a 
gap  of  about  thirty  miles.  However  closely 
the  two  ranges  may  be  associated  in  the  causes 
which  led  to  the  extrusion  of  their  lavas  and 
in  the  character  of  their  lavas,  thev  are  en- 
tirely  distinct  at  the  surface  and  are  separated 
by  sedimentary  and  igneous  rocks  belonging  to 
an  earlier  geological  period.  As  seen  from  the 
map  (Plate  H)  on  which  the  fonner  position  of 
the  Pacific  coast  line  is  shown,  the  volcanic 
vents  which  formed  the  Nicaraguan  range  broke 
out  upon  the  sea  bottom  and  extended  nearly 
parallel  to  the  western  coast.  The  northern 
vents  of  the  group  were  much  more  active  and 
have  given  rise  to  a  somewhat  continuous  moun- 
tain chain  and  also  to  the  extensive  Jinotepe 
plateau. 

FOEMATION    OF   LaKE   NICARAGUA. TllC    posi- 

tion  of  these  volcanic  vents  with  reference  to  the 
coast  line  was  such  that  when  their  ejected  ma- 
terial had  reached  the  surface  of  the  sea  it 
formed  a  barrier  across  the  Bay  of  Nicaragua. 
This  barrier  was  built  gradually  higher  by  suc- 
cessive eruptions,  and  since  in  the  area  behind 
it  precipitation  was  greater  than  evaporation,  the 
waters  rose  above  sea  level  and  doubtless  escaped 
westward  over  the  barrier  during  the  occasional 
periods  of  quiescence  in  the  volcanic  activity. 
As  the  surface  of  the  barrier  was  raised  by  suc- 
cessive additions  of  volcanic  ejecta,  the  surface 


APPENDIX  II.— GEOLOGIC  REPORT 


145 


of  the  impounded  waters  was  raised  to  a  height 
probably  somewhat  above  the  present  elevation 
of  Lake  ^Nicaragua.  The  lake  thus  formed  occu- 
pied not  only  the  position  of  the  former  bay  but 
flooded  the  basins  of  the  tributary  streams.  Its 
surface  finally  reached  the  lowest  point  in  the 
Continental  Divide  where  a  westward-flowing 
stream  headed  against  one  which  occupied  the 
present  position  of  the  San  Juan.  When  this 
point  was  reached,  the  intermittent  escape  of  the 
impounded  waters  across  the  volcanic  dam  to  the 
westward  was  changed  for  a  permanent  outlet 
to  the  eastward.  The  gap,  when  first  discovered 
and  overtopped  by  the  rising  waters,  was  doubt- 
less underlain  by  deeply  weathered  rock  and 
residual  clay.  This  must  have  been  very  rapidly 
cut  down  by  the  escaping  waters  until  the  under- 
lying hard  rock  was  reached,  when  the  perma- 
nent level  of  the  lake  was  established  which  it 
has  retained  practically  unchanged  to  the  present 
time. 

It  is  quite  possible  that  the  gaps  through  the 
Continental  Divide  to  the  east  and  through  the 
divide  across  the  western  strip  of  land,  between 
the  former  bay  and  the  Pacific  ocean,  were  so 
near  the  same  level  that  the  lake  had  for  a  short 
time  an  outlet  both  to  the  Atlantic  and  the 
Pacific. 

An  examination  of  a  portion  of  the  Rio 
Grande  gorge  possibly  throws  some  light  on  this 
point.  From  the  point  where  the  Rio  Grande 
turns  abruptly  to  the  northwest  in  the  reversed 
channel  of  the  streams  which  formerly  flowed 
eastward,  for  a  distance  of  four  or  five  miles  to 
the  point  where  the  gorge  opens  out  to  the  allu- 
vial plain  bordering  the  lower  river,  there  is  an 
old  channel  which  has  been  partially  silted  up  by 
the  present  river.  The  stream  only  occasionally 
touches  the  rock  walls  of  the  gorge  on  the  con- 
vex sides  of  its  meanders.  At  the  same  time  it 
10 


nowhere  departs  wholly  from  the  old  channel, 
that  is,  it  nowhere  has  the  character  of  a  super- 
posed stream.  It  is  evident  that  the  present 
stream  is  smaller  than  one  which  excavated  and 
formerly  occupied  this  valley.  There  are  three 
ways  in  which  the  present  conditions  might  have 
been  brought  about: 

1.  The  present  valley  might  have  been  occu- 
pied by  a  stream  which  was  once  larger  than  at 
present,  but  which  has  suffered  a-^partial  diver- 
sion of  its  headwaters  by  capture  through  the 
encroachment  of  a  neighboring  stream.  This 
possible  explanation,  however,  is  not  applicable 
in  this  case,  since  the  Rio  Grande  is  itself  a  grow- 
ing stream  and  is  constantly  adding  to  its  drain- 
age area,  and  hence  to  its  volume  by  encroaching 
on  the  basins  of  its  neighbors.  There  is  no 
evidence  from  the  arrangement  of  the  drainage 
in  this  region  that  the  Rio  Grande  has  ever  lost 
any  territory  in  this  way. 

2.  The  former  volume  of  the  Rio  Grande 
might  have  been  greater  by  reason  of  different 
climatic  conditions  which  at  some  former  time 
gave  the  region  a  greater  rainfall  than  it  now 
has.  There  is  no  direct  evidence  in  favor 
of  this  hypothesis.  So  far  as  known  there  is  no 
evidence  whatever  that  the  rainfall  has  ever  been 
greater  in  this  region  than  it  is  at  the  present 
time.  On  the  contrary,  if  a  greater  rainfall  had 
been  the  cause  of  the  old  valley  this  condition 
would  have  been  general  in  its  effects  and  all  the 
streams  of  the  region  would  show  the  same  evi- 
dence of  greater  volume  in  the  past.  So  far  as 
known,  however,  the  Rio  Grande  is  exceptional 
in  this  respect. 

3.  The  third  possible  explanation  is  that  the 
lake  may  have  found  an  outlet  for  a  short  time 
by  way  of  the  Rio  Grande  valley.  As  pointed 
out  above,  the  lake  rose  behind  the  barrier 
formed  of  the  volcanic  ejecta  until  the  level  of 


146 


NICARAGUA  CANAL  COMMISSION 


the  impounded  waters  reached  the  lowest  gap 
in  the  Continental  Divide  where  they  spilled 
over  and  escaped  by  way  of  a  river  channel 
leading  eastwanl  to  the  Caribbean.  Now  the  ma- 
terial forming  the  gap  in  the  Divide  must  have 
been  residual  clay  and  deeply  w^eathered  rock, 
material  which  would  be  rather  readily  removed 
by  the  corrasion  of  the  escaping  waters.  Also 
a  study  of  the  present  river  gorge  where  the 
Continental  Divide  formerlv  existed  shows  that 
the  channel  has  here  been  considerablv  lowered. 
It  does  not  seem  at  all  improbable,  therefore, 
that  the  lake  for  a  short  time  may  have  been 
fifty  or  more  feet  higher  than  now  with  refer- 
ence to  the  surrounding  country.  But  if  it 
were  raised  fifty  feet  its  waters  w^ould  escape 
by  the  Lajas-Grande  gap  westward  to  the  Pa- 
cific. It  seems  possible  that,  when  the  w^aters  of 
the  lake  were  first  raised  by  the  growing  barrier 
to  the  northwest,  they  found  two  gaps  at  ap- 
proximately the  same  altitude  and  for  a  time 
escaped  in  part  eastward  to  the  Atlantic  and  in 
part  w-estward  to  the  Pacific.  Active  corrasion 
of  the  two  outlets  began  at  once.  The  gorge  of 
the  Rio  Grande  was  excavated,  but  the  gap  in 
the  main  divide  in  the  east  was  at  first  in  less 
resistant  material  and  was  consequently  cut 
down  the  more  rapidly.  By  the  time  hard  rock 
was  reached  in  this  gap  the  w^aters  had  been  en- 
tirely withdrawn  from  the  western  outlet.  The 
eastward  tilting  of  the  region  west  of  the  lake 
may  have  continued  well  into  this  period  and 
have  been  in  some  measure  instrumental  in 
finally  turning  the  outlet  to  the  east. 

It  is  possible  that  at  first  the  gap  in  the  main 
divide  to  the  east  was  so  much  higher  than  the 
one  to  the  west  that  all  the  water  escai>ed  by  the 
latter;  that  the  backward  cutting  of  the  east- 
ward flowing  stream  lowered  a  gap  in  the  divide 
and  by  reason  of  the  less  resistant  material  of 


which  it  w^as  composed  diverted  at  first  a  part  and 
finallv  all  the  waters  of  the  lake  to  the  eastward. 
This  is  only  a  modification  of  the  third  hy- 
pothesis and  does  not  affect  the  main  point, 
namely,  that  for  a  longer  or  shorter  period  the 
lake  had  two  outlets,  one  by  the  Lajas-Grande 
gap  and  the  other  by  the  valley  of  the  present 
San  Juan.^ 

This  modification  of  the  hypothesis  removes 
one  of  the  most  serious  objections  to  the  above- 
stated  theory  for  the  origin  of  the  lakes.  An 
examination  of  the  region  which  it  assumes  to 
have  been  occupied  by  the  Continental  Divide 
leads  to  the  conclusion  that  the  lowest  gap  in 
the  Divide  was  probably  more  than  fifty  feet 
above  the  present  river.  An  elevation  for  the 
present  divide  above  the  San  Juan  at  Castillo 
of  one  hundred  feet  or  possibly  more  would  ac- 
cord better  than  an  elevation  of  fifty  feet  or  less 
with  the  topography  and  drainage  of  the  region 
and  wuth  the  characteristics  of  divides  in  gen- 
eral. And  it  is  by  no  means  impossible  that 
the  backward  cutting  of  the  eastward  flowing 
stream  should  lower  the  gap  fifty  or  seventy-five 
feet  in  residual  clay,  while  the  outlet  of  the  lake 
was  cutting  the  four  or  five  miles  of  ruck  gorge 
now  occupied  by  the  Rio  Grande. 

Subsequent  Modification  of  the  Lake. — 
The  original  outline  of  the  lake  formed  behind 
the  bari'ier  of  volcanic  ejecta  was  probably  quite 
different  from  that  of  the  present  lakes.     The 


'  In  support  of  the  above  theory  for  the  origin  of  Lake 
Nicaragua  some  evidence  may  be  deduced  from  its  fauna. 
As  is  well  known,  the  lake  contains  many  sharks  and  sword 
fish.  These  characteristically  marine  forms  have  evidently 
occupied  a  body  of  salt  water  which  has  been  separated 
from  the  ocean  by  a  barrier  they  were  unable  to  pass,  and 
subsequently  so  gradually  freshened  that  they  have  been 
able  to  adapt  themselves  to  the  changed  conditions.  Of 
special  significance  is  the  fact  communicated  to  the  writer 
by  Dr.  Theo.  Gill  that  the  sharks  of  Lake  Nicaragua  are 
specifically  identical  with  those  found  in  adjacent  portions 
of  the  Pacific,  but  distinct  from  those  found  in  the  Carib- 
bean. 


APPENDIX  II.— GEOLOGIC  REPORT 


147 


subsequent  modification  has  been  due  to  several 
agencies.  The  continuation  of  volcanic  erup- 
tions lias  doubtless  very  much  contracted  the 
northwestern  portion  of  the  depression.  It  is 
probable  that  the  original  depression  was  occu- 
pied by  a  single  lake  which  extended  northwest- 
ward beyond  the  present  limits  of  Lake  Man- 
agua. Later  eruptions  encroached  upon  this 
portion  of  the  lake  basin,  and  finally  a  flood  of 
volcanic  ash  and  mud  was  carried  entirely  across 
the  depression,  forming  a  barrier  which  cut  off 
the  upper  portion  of  the  lake,  raising  its  surface 
between  thirty  and  fortv  feet  above  the  sur- 
face  of  the  larger  portion  to  the  southeast.  The 
strip  of  land  separating  the  two  lakes  is  a  nearly 
perfect  plain  composed  of  partially  consolidated 
volcanic  tuff.  The  Tipitapa  river  which  forms 
the  outlet  of  Lake  Managua,  crossing  this  bar- 
rier has  cut  its  channel  backward  nearly  to  the 
upper  lake.  It  falls  about  thirteen  feet  within 
less  than  half  a  mile  of  the  point  where  it 
emerges  from  Lake  Managua.  In  a  very  short 
time,  therefore,  unless  the  backward  cutting  of 
this  stream  is  arrested,  the  level  of  Lake  Man- 
agua will  be  lowered  to  the  extent  of  thirteen 
feet.  The  original  outline  of  Lake  Nicaragua 
has  further  been  slightly  modified  by  the  recent 
volcanic  eruptions  in  the  vicinity  of  Madera 
and  Ometepe  and  perhaps  also  of  Mombacho. 
The  northeastern  side  of  the  latter  volcano  ap- 
pears to  have  suffered  an  enormous  landslide, 
which  has  pushed  before  it  a  gi'eat  mass  of 
earth  and  rock.  This  now  has  a  peculiar  hum- 
mocky  surface  and  forms  a  long  point  project- 
ing into  the  lake  and  a  large  number  of  small 
islands. 

The  outline  of  the  lake  has  further  been 
modified  bv  the  action  of  the  waves.  The  trade 
winds  produce  a  nearly  constant  surf  on  its  west- 
ern side*  and  this  has  accomplished  considerable 


erosion  at  certain  j)oiiits.  The  wave  action  has 
probably  cut  a  shelf  into  the  adjoining  plain  en- 
tirely around  this  portion  of  the  lake,  the  extent 
of  the  shelf  depending  upon  the  character  of  the 
rocks  which  were  encountered  by  the  waves.  In 
the  region  south  of  Madera  bold  headlands  are 
formed  by  masses  of  hard  igneous  rocks  which 
tend  to  protect  the  less  resistant  rocks  between. 
At  some  points  the  steeply  inclined  sedimentary 
rocks  contain  certain  beds  of  sandstone  which 
are  much  more  resistant  than  the  mass  of  the 
formation,  and  these  form  parallel  ledges  which 
extend  into  the  waters  of  the  lake  in  some  cases 
a  mile  or  more,  the  softer  rocks  between  having 
been  removed  by  the  wave  action  to  a  consider- 
able depth.  Some  estimate  may  be  made  as  to 
the  extent  of  the  wave-cut  terrace  along  the  lake 
shore  west  of  Ometepe  from  the  height  of  the 
cliff.  The  Rivas  plain  has  an  average  slope  of 
about  eight  feet  to  the  mile,  and  it  is  assumed 
that  this  plain  extends  to  the  eastward  under 
the  waters  of  the  lake.  If  it  retains  the  same 
slope  a  cliff  24  feet  in  height  would  represent  a 
terrace  at  least  three  miles  broad.  It  is  prob- 
able that  the  wave-cut  terrace  varies  between  two 
and  four  miles  along  this  portion  of  the  shore. 
From  Zapatera  northward  to  Granada  the  wave- 
action  is  more  efficient  than  on  any  other  portion 
of  the  lake  by  reason  of  the  greater  sweep  which 
the  prevailing  winds  and  waves  possess.  Since 
the  shore  is  here  composed  of  only  partially  con- 
solidated volcanic  ash,  the  modification  of  its 
outline,  due  to  wave  action,  has  been  very  con- 
siderable. It  is  probable  that  this  action  has 
severed  Zapatera  from  the  mainland  and  that  the 
many  islands  surrounding  it  were  originally  por- 
tions of  that  volcanic  cone.  They  probably 
represent  the  more  resistant  lavas  from  which  the 
softer  materials  have  been  washed  awav. 

The  modification  of  the  northeastern  shore  of 


148 


NICARAGUA  CANAL  COMMISSION 


the  lake  by  wave  action  has  been  extremelv 
slight.  This  portion  of  the  lake  shore  is  without 
a  beach,  and  only  rarely  is  there  any  considerable 
surf.  Hence  only  a  few  |X)int3  which  project 
well  out  into  the  lake  show  anv  effect  of  wave 
action. 

The  material  eroded  bv  the  waves  from  the 

*. 

western  shore  has  been  carried  northward  bv 
the  action  of  the  waves  and  deposited  in  the 
upper  end  of  the  lake.  A  bar  has  been  built 
across  the  point  of  the  lake  enclosing  a  broad, 
shallow  lagoon  behind  it,  and  the  outlet  of  Lake 
Managua  has  been  pushed  northward  by  the 
sand  drift  well  toward  the  northern  margin  of 
the  vallev. 

The  third  way  in  which  the  outline  of  the  lake 
has  been  modified  is  by  the  building  out  of  its 
shores  by  material  brought  down  by  tributary 
streams.  The  effect  of  this  is  seen  almost  ex- 
clusively along  the  southern  and  eastern  shores. 
Elsewhere  the  constant  surf  and  consequent  lit- 
toral currents  have  been  sufficient  to  distribute 
the  sediment  as  rapidly  as  brought  down  by 
tributary  streams,  so  that  not  onlv  have  no  addi- 
tions  been  made  to  the  lake  shore  but  the  new 
material  added  has  not  been  sufficient  to  com- 
pensate for  the  wave  erosion.  When  the  waters 
first  occupied  the  depression  behind  the  barrier 
to  the  northwest,  the  outline  of  the  lake  must 
have  been  quite  iiTegular,  since  it  filled  a  river 
basin,  some  portion  of  which  had  rather  strong 
relief.  !Much  of  its  basin  occupied  a  region 
which  had  been  comparatively  well  base-leveled, 
but  its  waters  als()  extended  up  the  valleys  where 
the  divides  remained  in  strong  relief.  Many 
shallow  estuaries  were  thus  formed,  and  these 
have  subsequently  been  entirely  filled  with  sedi- 
ment by  the  streams  entering  their  heads.  The 
most  extensive  filling  was  at  the  southeastern 
end  of  the  lake  where  the  largest  tributaries  en- 


ter it.  It  is  evident  that  the  broad  swampy  plains 
bordering  the  Itio  Frio  and  the  upper  San  Juan 
were  originally  portions  of  the  lake  which  have 
subsequently  been  silted  up. 

Reference  has  been  made  to  the  effect  of  the 
Costa  Eican  volcanoes  upon  the  drainage  of  the 
Xicaraguan  depression.  The  series  of  eruptions 
which  give  rise  to  this  range  probably  broke  out 
in  a  land  area  on  which  there  was  a  well-devel- 
oped system  of  drainage,  similar  to  that  north  of 
the  present  San  Juan  valley.  This  drainage 
system,  however,  was  entirely  obliterated,  and  a 
new  divide  was  established  following  the  line 
on  which  the  vehts  were  located.  The  effect  of 
this  was  to  greatly  enlarge  the  drainage  area  of 
the  San  Juan.  The  streams  which  were  devel- 
oped on  the  northern  sides  of  the  rising  volcanoes 
were  compelled  by  the  slope  of  the  region  to 
flow  northward,  where  they  intersected  the  heads 
of  the  small  tributaries  of  the  San  Juan.  This 
resulted  in  the  composite  courses  of  the  present 
southern  tributaries  of  the  San  Juan,  which  has 
already  been  pointed  out  and  explained.  The 
eruptions  of  the  Costa  Itican  volcanoes  not  only 
added  to  the  drainage  area  of  the  San  Juan,  but 
also  furnished  its  southern  tributaries  wnth  an 
abundant  supply  of  unconsolidated  material. 

PHYSIOGRAPHY  OF  THE  SAX  JUAX 

VALLEY. 

In  the  foregoing  account  of  the  topography  of 
the  region  and  its  recent  geological  history  many 
of  the  peculiarities  of  the  San  Juan  river  have 
been  referred  to  or  partially  described.  This 
river  and  its  valliy,  however,  bear  such  an  inti- 
mate relation  to  any  canal  scheme  that  a  some- 
what  more  explicit  account  should  be  given 
of  its  peculiarities. 

Physiographic  Subdivisions  of  the  Riveb 
AND  Valley. — Considered  from  any  point  of 


APPENDIX   H.—GEOLOGIC   REPORT 


149 


view,  either  with  reference  to  the  history  of  its 
development,  the  present  character  of  its  chan- 
nel and  banks,  or  the  problem  of  utilizing  it  for  a 
canal  route,  the  San  Juan  river  falls  naturally 
into  three  sections.  Starting  from  the  point 
where  it  leaves  Lake  Nicaragua  the  first  extends 
to  the  head  of  the  Toro  rapids,  the  second  from 
the  head  of  the  Toro  rapids  to  the  mouth  of  the 
San  Carlos  river,  and  the  third  from  the  mouth 
of  the  San  Carlos  river  to  the  sea.  These  three 
sections  will  be  taken  up  in  order,  and  their  pe- 
culiar features  pointed  out  in  some  detail. 

The  Upper  Division. — The  distance  from  the 
lake  to  the  head  of  the  Toro  rapids  by  the  river 
is  about  twentv-seven  miles.  In  this  distance 
the  river  receives  a  number  of  tributaries,  but 
none  of  any  size,  unless  the  Eio  Frio  be  regarded 
as  a  tributarv  of  the  San  Juan.  The  Frio  enters 
the  latter  at  the  point  where  it  leaves  the  lake, 
and  its  mouth  is  separated  from  the  lake  only  by 
a  narrow  tongue  of  swampy  land  which  is  sub- 
merged at  high  water.  In  this  upper  section  the 
San  Juan  river  has  a  moderate  current  and  a 
considerable  depth.  Its  banks  are  low  and 
swampy  except  where  its  meanders  bring  it 
against  the  foot  of  one  of  the  numerous  hills 
which  rise  above  the  alluvial  plain.  It  is  evi- 
dent that  the  lake  formerlv  extended  down  to 
this  point  and  considerably  beyond,  and  that  a 
large  amount  of  territory  has  been  reclaimed 
from  the  waters  of  the  lake.  The  ordinarv 
method  bv  which  lakes  are  obliterated  is  bv  the 
filling  from  their  upper  ends  and  by  the  cutting 
down  at  their  outlets.  In  this  case,  however,  a 
part  of  this  process  is  exactly  reversed.  The 
lake  is  being  filled  most  rapidly  from  its  lower 
end.  This  filling  is  manifestly  accomplished  not 
by  the  water  which  comes  from  the  lake,  since 
this  is  practically  clear,  but  by  the  tributaries 
which  enter  this  lower  portion.     The  present 


river  channel  does  not  necessarilv  coincide  with 

t' 

the  position  of  the  river  which  formerly  occu- 
pied this  basin.  Its  present  position  is  depen- 
dent upon  the  relative  amounts  of  sediment 
brought  down  by  the  tributaries  upon  either  side. 
If  the  Castillo  and  Toro  rapids  were  cut  back 
and  the  channel  of  the  river  permitted  to  sink 
through  the  alluvium,  forming  the  greater  part 
of  its  banks  and  bed,  upon  the  old  land  surface 
which  the  alluvium  conceals,  it  would  have  the 
characteristics  of  a  superposed  stream.  At 
numerous  points  where  its  present  channel  does 
not  follow  the  old  channel,  it  would  discover 
hard  rocks  in  its  downward  cutting.  In  its 
present  condition  this  may  be  described  as  a 
residual  river  channely  that  is,  a  broad  arm  of 
the  lake  has  been  gradually  constricted  by  the 
addition  of  sediments  on  its  margin,  and  all  that 
remains  is  the  narrow  river  channel  kept  open 
by  the  current  of  the  water  flowing  from  the 
lake.  To  make  a  navigable  canal  it  is  evident 
that  the  channel  of  the  river  can  be  followed  the 
greater  part  of  this  distance,  the  material  to  be 
excavated  in  order  to  obtain  the  requisite  depth 
being  alluvial  silt  and  sand.  At  certain  points, 
however,  the  river  in  its  meanders  impinges 
upon  the  hills  which  border  the  valley  or  rise 
above  its  level  surface,  and  here  if  the  channel 
of  the  river  were  followed  it  would  be  neces- 
sary to  excavate  in  rock.  Knowing  the  origin 
of  the  alluvial  plain,  it  is  evident  that  at  such 
points,  by  shifting  the  line  away  from  the  hills 
a  short  distance,  the  surface  of  the  rock  will  pass 
below  the  excavation  line  of  the  canal  and  the 
latter  will  be  entirely  in  alluvium.  The  recog- 
nition of  this  point  will  effect  a  very  material 
saving  in  the  building  of  the  canal,  and  at  the 
same  time  will  improve  its  alignment. 

The  Middle  Division. — The  second  section 
of  the  river  extends  from  the  head  of  the  Toro 


150 


NICARAGUA  CANAL  COMMISSION 


rapids  to  the  mouth  of  the  San  Carlos.  Its 
essential  characteristic  is  the  rapid  fall  of  the 
river  and  the  narrow  valley  in  which  it  flows. 
The  Toro  rapids  which  retain  the  lake  at  its 
present  level  are  not  formed  by  a  solid  ledge  of 
rocks  crossing  the  valley,  but  by  boulders,  sand 
and  clay.  It  is  some  distance  below  the  Toro 
rapids  that  the  rock  is  first  found  crossing  the 
valley. 

It  appears  that,  when  this  arm  of  the  lake  ex- 
tended down  to  the  Continental  Divide,  it  re- 
ceived a  rather  large  and  swift  tributary,  the 
Rio  Sabalos,  near  its  head.  The  sediment  car- 
ried by  the  Sabalos,  consisting  of  clay,  sand  and 
boulders,  was  deposited  on  reaching  the  quiet 
water  of  the  lake.  A  delta  was  thus  formed, 
which  extended  across  this  arm  of  the  lake, 
forming  a  shoal.  As  the  river  channel  sank  in 
the  gap  across  the  Divide,  the  latter  became 
lower  than  the  surface  of  the  Sabalos  delta,  and 
the  crest  of  the  dam  w^hich  retained  the  surface 
of  Lake  Nicaragua  moved  westward  from  its 
original  position  on  the  Divide  to  the  present 
position  of  the  Toro  rapids.  It  is  evident  that 
the  dam  formed  of  this  unconsolidated  material 
is  only  very  temporary,  and  that  the  backward 
cutting  of  the  river  channel,  unless  artificially 
checked,  will  soon  low^er  this  barrier  and  eventu- 
allv  affect  the  level  of  the  lake. 

It  is  difficult  to  determine  exactly  the  position 
of  the  old  divide.  It  undoubtedly  crossed  the 
valley  of  the  present  San  Juan  below  the  mouth 
of  the  Poco  Sol.  That  stream  has  evidently  in- 
herited the  lower  portion  of  its  course  from  a 
tributary  to  the  stream  flowing  northwest.  The 
Santa  Cruz  also  probably  belonged  to  the  west- 
ern drainage.  The  general  course  of  the  Bar- 
tola,  on  the  other  hand,  indicates  that  it  be- 
longed to  the  eastern  system.  Hence  the  divide 
was  probably  between  the  Bartola  and  the  Santa 


Cruz.  It  may  have  been  at  the  present  Castillo 
rapids,  although  it  is  prol>able  that  the  rapids 
would  show  some  recession  due  to  erosion  since 
the  lake  was  formed.  This,  however,  might  be 
comparatively  little  by  reason  of  the  character 
of  the  rocks,  and  the  fact  that  the  river  at  this 
point  carries  comparatively  little  coarse  sedi- 
ment and  hence  is  relativelv  inefficient  in  cor- 
rading  its  channel. 

From  the  head  of  the  Toro  rapids  to  Ma- 
chuca  the  river  channel  consists  of  rather  long 
quiet  reaches  separated  by  rapids.  The  total 
fall  in  this  section  is  about  forty  feet,  or  an 
average  of  about  two  feet  to  the  mile.  Of  this 
fall  all  but  about  six  feet  is  accomplished  by  the 
numerous  rapids.  Between  the  Bartola  and 
Machuca  creeks  ra])ids  appear  to  be  due  to  the 
unequal  hardness  of  the  underlying  rocks,  and 
their  position  is  probably,  in  large  measure, 
permanent,  the  intervening  quiet  stretches  being 
located  upon  softer  rocks  which  are  worn  down 
by  the  moderate  cun*ent  more  rapidly  than 
the  harder  rocks  bv  the  swift  current  of  the 
rapids. 

Between  Machuca  and  the  mouth  of  the  San 
Carlos  the  river  is  deep  and  narrow  and  the  cur- 
rent is  generally  moderate.  In  some  places  at 
low  stages  of  the  river  it  is  almost  imperceptible, 
and  when  the  San  Carlos  is  in  flood  the  current 
in  this  portion  of  the  channel  may  even  set  up- 
stream for  a  time.  The  water  has  a  depth  var^'- 
ing  between  fifteen  and  sixty  feet,  the  bottom 
of  the  channel  at  some  points  being  below  sea 
level.  It  is  evident  that  the  present  river  is 
flowing  in  a  channel  which  had  been  cut  when 
the  land  stood  higher  than  now  and  which  has  not 
yet  been  filled  by  sediment.  Where  tributaries 
join  the  river  they  have  deposited  small  deltas 
in  its  channel,  sometimes  shoaling  it  entirely 
across.     But  the  amount  of  sediment  delivered 


APPENDIX  II.— GEOLOGIC  REPORT 


151 


to  the  river  by  its  upper  tributaries  has  evidently 
been  no  greater  than  its  waters  were  able  to 
transport,  even  with  the  moderate  current  which 
prevails  in  this  part  of  tho  channel.  It  is  im- 
portant to  note  that  although  not  enough  sedi- 
ment has  been  delivered  to  the  river  above  this 
point  to  fill  its  old  channel,  the  river  has  built  up 
occasional  narrow  flood-plains.  It  is  evident 
that,  while  the  sediment  was  of  such  a  character 
and  in  such  quantity  that  it  could  be  readily 
transported  by  the  river  in  the  unobstructed 
channel,  it  was  retained  by  the  vegetation  upon 
the  banks,  and  in  this  way  served  to  build  up  the 
surface  of  the  flood-plains. 

The  Lo^rER  Division. — The  third  section  of 
the  river  extends  from  the  mouth  of  the  San 
Carlos  to  the  Caribbean  sea.  With  the  en- 
trance of  the  San  Carlos  the  character  of  the 
San  Juan  is  entirely  changed.  Above  this  it 
is  a  comparatively  clear  stream  and,  except  at 
the  rapids,  has  only  a  moderate  current.  Below 
the  entrance  of  the  San  Carlos  it  is  usually 
muddy,  is  shallow  with  a  shifting  sandy  bed  and 
has  a  uniformly  strong  current.  Its  slope  is 
verv  nearlv  a  foot  to  the  mile  in  this  section. 
The  Sarapiqui  is  very  similar  in  character  to 
the  San  Carlos,  although  it  is  somewhat  smaller. 
Heading  in  the  Costa  Rican  volcanoes  it  also 
carries  a  large  amount  of  sand  which  it  delivers 
to  the  San  Juan.  Many  of  the  smaller  tribu- 
taries of  the  San  Juan  deliver  practically  no  sedi- 
ment to  the  main  stream.  The  flood-plain  of  the 
latter  has  been  built  up  so  rapidly  that  they  are 
ponded  in  their  upper  courses,  and  the  lagoons 
thus  made,  filled  with  vegetation,  form  settling 
basins  or  filters  which  effectually  remove  all  sedi- 
ment from  their  waters.  They  reach  the  San 
Juan  as  clear  streams,  except  that  their  waters 
are  discolored  by  decaying  vegetation.  Below 
the  mouth  of  the  Sarapiqui  the  channel  of  the 


San  Juan  bends  slightly  to  the  northward  and 
very  distinctly  follows  the  northern  margin  of 
the  valley.  This  position  is  probably  due  to 
the  more  abimdant  supply  of  material  furnished 
by  the  southern  tributaries  and  to  the  northward 
drift  of  the  littoral  current  in  the  Caribbean 
sea.  Although,  as  stated  on  a  previous  page, 
the  subsidence  which  permitted  the  San  Juan 
and  its  tributaries  to  silt  up  their  valleys,  was 
probably  slow,  the  head  of  the  estuary  formed 
by  the  drowning  of  the  lower  valleys  may  have 
extended  at  least  as  far  as  the  mouth  of  the 
Sarapiqui.  As  the  river  extended  its  course 
eastward  by  the  filling  of  the  estuary  and  later 
by  the  foraiation  of  the  delta  plain,  it  would  be 
continually  crowded  to  the  northward  by  the 
direction  of  sand-drift  along  the  coast.  This 
tendency  became  more  pronounced  the  farther 
out  the  delta  was  built,  and  the  sharp  northward 
bend  of  the  lower  San  Juan  is  its  direct  conse- 
quence. As  the  river  channel  was  carried 
northward,  this  portion  of  the  valley  would  be 
filled  first  and  to  a  higher  level  than  the  southern 
portion.  The  river  would  thus  at  times  find 
itself  in  a  position  of  unstable  equilibrium  and 
would  seek  a  new  channel  on  the  lower  part  of 
the  delta  plain  to  the  southward.  Thus  it  is 
probable  that  the  river  originally  occupied  the 
present  position  of  the  San  Juanillo  (see  Plate 
I),  flowing  to  the  northward  between  the  spurs 
coming  down  from  the  Eastern  Divide  and  the 
Silico  hills,  the  latter  having  previously  formed 
a  group  of  islands.  This  position  was  probably 
occupied  until  the  coast  line  was  approximately 
at  the  point  where  the  San  Juanillo  and  Deseado 
now  unite.  It  then  gi*adually  deserted  its  north- 
em  channel  for  the  present  position  of  the  lower 
San  Juan.  Subsequently  the  latter  became  un- 
stable and  a  more  favorable  course  to  the  sea 
was  found  still  farther  south.     The  recent  clian- 


152 


NICARAGUA  CANAL  COMMISSION 


nel  of  the  Rio  Colorado  was  then  developed  at 
the  expense  of  the  lower  San  Juan.  This  pro- 
cess is  still  going  on,  and  the  relative  amounts  of 
water  carried  bv  the  two  channels  have  verv  ma- 
terially  changed  within  a  generation.     Unless 


artificially  modified,  the  lower  San  Juan  will 
continue  to  dwindle  and  practically  all  the  water 
will  find  its  way  to  the  sea  by  way  of  the  Colo- 
rado or  some  more  favorably  located  channel 
still  farther  southward. 


PART  II 

APPLICATION  OF  GEOLOGIC  FACTS  TO 

ENGINEERING  PROBLEMS 


The  foregoing  account  of  the  topography  and 
geology  of  the  Nicaraguan  depression  is  written 
from  the  view-point  of  the  geologist  rather  than 
the  engineer.  "While  it  contains  information 
which  it  is  believed  has  the  most  direct  and  im- 
portant bearing  upon  engineering  problems,  it 
also  contains  much  which  has  only  an  indirect 
bearing  upon  the  work  of  the  engineer,  and  even 
where  the  connection  is  the  most  intimate,  it  has 
not  generally  been  explicitly  pointed  out.  It 
remains,  therefore,  in  the  second  part,  to  treat 
the  region  from  the  view-point  of  the  engineer, 
and  to  make  explicit  the  application  of  the  geo- 
logic facts  to  the  engineering  problems.  Num- 
erous profiles  have  been  funiished  to  the  engi- 
neers showing,  so  far  as  the  infonnation  available 
permits,  the  geological  conditions  and  the  classi- 
fication of  materials  on  the  various  lines  in  ex- 
cavation, and  at  the  localities  where  it  is  planned 
to  construct  controlling  works,  as  dams,  locks, 
weirs,  etc.  Upon  these  profiles  the  estimates  are 
based  as  well  as  the  plans  of  the  canal  and  its 
appendages.     Very  much  fuller  and  more  reli- 


able information  is  at  hand  concerning  certain 
portions  of  the  line  than  others;  hence  the  in- 
formation conveyed  by  the  profiles  has  a  great 
variability  in  value.  It  is  diflicult  to  represent 
those  differences  upon  the  profiles  themselves, 
and  it  is  therefore  important  that  a  somewhat  de- 
tailed statement  should  be  made  concerning  the 
information  on  which  the  sections  are  based  and 
the  degree  of  confidence  with  which  they  should 
be  regarded.  The  attempt  will  be  made  in  this 
portion  of  the  report  to  discriminate  between 
that  which  is  known  from  actual  observation  and 
that  which  is  merelv  inferred. 

In  the  foregoing  chapters  upon  the  rock  for- 
mations and  rock  decav,  as  well  as  elsewhere 
throughout  the  report,  many  statements  have 
been  made  regarding  the  character  of  tlie  ma- 
terials with  which  the  engineers  will  have  to 
deal,  both  in  excavation  and  for  foundations. 
Xo  systematic  statement,  however,  has  been 
given  concerning  the  classification  of  materials 
adopted  and  the  basis  for  the  same.  The  classi- 
fication employed  will,  therefore,  be  explained 


APPENDIX   H.—GEOLOGIC   REPORT 


153 


in  detail,  although  some  repetition  of  statements 
made  in  other  portions  of  the  report  may  be  ren- 
dered necessary. 

CLASSIFICATIOK  OF  MATERIALS. 

All  the  materials  in  place  with  which  the  en- 
gineer will  have  to  deal  in  thd  construction  of 
the  Nicaragua  Canal,  have  been  for  convenience 
divided  into  four  classes,  viz.:  (1)  alluvium,  (2) 
residual  clay,  (3)  soft  rock  and  (4)  hard  rock. 
Each  class  presents  considerable  variety  in  the 
origin  and  physical  properties  of  the  materials 
which  it  embraces,  but  the  classification  is  a  prac- 
tical one  and  it  is  believed  to  be  sufficiently  de- 
tailed, at  least  for  preliminary  plans  and  esti- 
mates, if  the  following  explanation  is  kept  in 
view. 

Alluvium. — All  unconsolidated  material 
w^hich  has  been  transported  and  deposited  by 
streams  is  classed  as  alluvium.  Bv  reason  of 
the  recent  geologic  changes  which  have  taken 
place  in  this  region,  a  very  large  amoimt  of 
this  unconsolidated  material  is  encountered  on 
the  canal  line.  As  pointed  out  more  fully  else- 
where, this  entire  region  has  recently  stood  con- 
siderably higher  with  reference  to  sea  level  than 
now,  having  a  much  rougher  topography,  with 
comparatively  high  hills  and  deep  narrow  valleys. 
A  recent  subsidence  of  the  land  has  submerged 
many  of  these  valleys,  which  have  subsequently 
been  silted  up.  The  alluvium  varies  consider- 
ably in  composition,  depending  upon  the  source 
from  which  it  was  derived  and  the  manner  in 
which  it  was  deposited.  It  varies  all  the  way 
from  coarse,  clean-washed  sand  or  gravel  to 
the  finest  clay.  It  may,  for  convenience,  be 
separated  into  three  sub-classes,  viz.:  (1)  sand, 
(2)  silt,  a  variable  mixture  of  fine  sand 
and  clay,  and  (3)  clay  silt,  composed  chiefly  of 
clay   with   little   or   no  sand.     All   three   sub- 


classes contain  variable  quantities  of  vegetable 
matter. 

On  the  west  side  the  alluvium  is  derived 
chiefly  from  the  wearing  down  of  calcareous 
shales  and  sandstones,  with  only  a  few  igneous 
rocks.  It  consists,  therefore,  chiefly  of  fine  sand 
with  comparatively  little  clay,  although  there  is 
usually  enough  cementing  material  to  make  it 
quite  compact.  In  the  Rio  Grande  flood-plain 
where  the  alluvium  fills  a  drowned  valley,  it 
becomes  in  general  somewhat  coarser  downward, 
and  at  the  surface  is  composed  of  characteristic 
flood-plain  deposits,  generally  very  fine,  sandy 
clay.  The  present  channel  of  the  Rio  Grande 
is  from  fifteen  to  twenty-five  feet  in  depth,  and 
its  sides  are  generally  steep,  often  nearly  or  quite 
vertical.  They  servo  to  show  the  capacity  of  the 
material  to  stand  at  very  steep  slopes.  It  would 
also  probably  form  fairly  impervious  embank- 
ments. ^ 

The  level  land  bordering  the  upper  San  Juan 
from  the  lake  ^  to  Savalos '  consists  of  alluvium 
brought  down  for  the  most  part  by  streams  head- 
ing upon  deeply  decayed  igneous  rocks.  It 
consists  largely,  therefore,  of  the  finest  clay  silt, 
much  of  it  containing  no  perceptible  grit.  Some 
fine  sand  is  found  in  the  river  channel  where  it 
remains  as  a  residuum  separated  from  a  large 
amount  of  sediment,  the  sluggish  current  of  this 
portion  of  the  river  not  being  able  to  transport 
the  heavier  particles.  The  clay  silt  in  this 
region  has  usually  a  gray  or  bluish  color.  Be- 
tween Savalos  and  the  Boca  San  Carlos  the  flood- 
plains  are  not  extensive,  but  the  alluvium  of 
which  they  are  composed  is  similar  in  character 
to  that  bordering  the  upper  river.  Below  the 
San  Carlos  there  is  much  greater  variation  in 
its  character,  since  the  material  brought  down  by 
that  stream  is  entirely  different  from  any  derived 
from  the  adjoining  country.     It  consists  largely 


154 


NICARAGUA   CANAL  COMMISSION 


of  sand,  the  larger  grains  well  rounded,  but  the 
smaller  ones  quite  angular.  The  prevailing 
color  is  black  with  a  few  grains  of  red  or  white 
minerals.  The  sand  is  entirely  of  volcanic  ori- 
gin, evidently  a  finely  comminuted,  fresh  vol- 
canic rock  broken  up  and  ejected  by  explosive 
volcanic  eruptions.  This  sand  is  transported 
chiefly  by  rolling  along  the  bottom  of  the  river, 
so  that  only  the  very  finest  portions  reach  the 
flood-plain.  It  forms  the  filling  material  of  the 
old  river  channel  under  the  bed  of  the  present 
stream.  A  section  taken  in  the  flood-plain,  a 
little  distance  from  the  river  channel,  reveals 
fine  sandy  silt  for  a  considerable  distance  down- 
ward, with  perhaps  some  beds  of  black  sand  to- 
ward the  bottom.  It  seems  that  as  the  river 
gradually  built  up  its  bed  to  preserve  a  normal 
gradient  with  increasing  length,  the  deposit  on 
the  flood-plain  nearly  always  kept  it  so  far  above 
the  bed  of  the  stream  that  the  coarser  sediment 
transported  by  tJie  latter  was  not  spread  over 
its  surface.  Enough  of  the  finer  portions  of 
this  volcanic  sand,  however,  were  deposited  on 
the  flood-plain  in  the  immediate  vicinity  of  the 
river,  to  materially  modify  the  character  of  the 
alluvium.  Of  the  manv  tributaries  of  the  San 
Juan  only  the  San  Carlos  and  the  Sarapiqui 
carry  volcanic  sand  of  this  character.  The 
basins  of  the  smaller  streams  are  located  entirely 
upon  areas  of  deeply  weathered  rocks,  and  the 
sediment  which  they  bear  consists  of  the  pro- 
ducts of  decay  derived  from  these  rocks.  The 
only  mineral  which  has  withstood  the  process  of 
rock  w^eathering  is  quartz,  and  this  is  not  found 
in  suflficient  abundance  in  any  of  these  fonna- 
tions  to  materially  modify  the  sediment  derived 
from  them;  hence  the  outer  portions  of  the  San 
Juan  flood-plain  in  which  the  material  is  de- 
rived from  the  sediment  borne  bv  the  smaller 
streams,  diifer  in  character  from  those  imme- 


diately bordering  the  San  Juan  itself.  Not  only 
is  the  deposition  near  the  main  stream  more 
rapid,  so  that  the  current  of  the  tributaries  is 
checked  and  lagoons  are  formed,  but  the  allu- 
vium, consisting  in  one  case  of  fine  sand  with 
a  matrix  of  clay,  is  relatively  much  firmer  than 
that  which  is  composed  of  fine  clay  and  vegeta- 
ble matter  without  any  admixture  of  sand. 

The  material  forming  the  delta  of  the  San 
Juan  consists  almost  entirely  of  sand  within  a 
belt  about  four  or  five  miles  broad,  bordering 
the  Caribbean.  At  some  distance  from  the 
coast  this  is  overiain  by  a  thin  stratum  of  fine 
swamp  mud  which  increases  in  thickness  toward 
the  inner  margin  of  the  delta  plain. 

The  alluvium  is  everywhere  of  such  character 
that  it  can  be  easily  handled  with  dredges.  Almost 
evervwhere  it  is  suflScientlv  solid  to  stand  at 
moderate  slopes,  the  slope  of  one  on  one  probably 
being  sufficient.  In  some  cases,  as  in  the  Flor- 
ida lagoon,  special  precautions  may  be  needed  to 
preserve  the  slopes.  The  material  becomes  very 
hard  when  dry,  and  even  when  it  is  piled  up  so 
that  the  water  can  drain  off,  it  becomes  compara- 
tively firm.  This  is  shown  in  the  vertical  stream 
banks  where  drainage  is  possible,  while  the  same 
material  forms  a  soft  mud  in  the  swamps  at  some 
distance  from  the  stream  channels.  The  black 
sand  when  free  from  clay  is  of  course  quite  per- 
vious to  water  and  would  not  be  suitable  for 
banks  where  the  water  level  was  permanently 
different  on  its  two  sides.  This  material,  how- 
ever, will  not  be  encountered  bevond  the  site  of 
the  first  lock  on  the  proposed  low-level  line. 
It  is  probable  that,  wherever  the  canal  is  more 
than  half  in  excavation,  the  silt  will  form  banks 
sufficiently  impervious  to  hold  the  required 
height  of  water  without  the  addition  of  any 
other  material.  Where  the  head  is  greater  than 
fifteen  feet,  it  may  be  necessary  to  add  a  puddled 


APPENDIX   IL—GEOLOGIC   REPORT 


155 


core  to  the  bank  unless  the  latter  is  made  of 
extraordinary  thickness. 

Residual  Clay. — The  climatic  and  other 
conditions  which  prevail  in  Nicaragua  are  ex- 
tremely favorable  to  rock  decay,  and  the  final 
product  from  the  weathering  of  all  the  rocks  of 
the  region  is  nearly  the  same.  In  the  eastern 
division  this  final  product  is  red  clay.  West  of 
the  lake,  where  the  climatic  conditions  are  dif- 
ferent, the  product  is  a  gray  or  black  clay.  The 
red  clay  represents  the  zone  not  only  of  complete 
rock  decay,  but  also  of  complete  oxidation  of  all 
or  nearly  all  the  constituent  minerals.  The 
complete  oxidation-  and  the  accompanying  red 
color  usually  extend  only  to  a  moderate  depth, 
ten  to  thirty  feet,  while  the  rock  decay  usually 
extends  much  farther.  The  red  clay  passes,  by 
more  or  less  abrupt  transition,  into  a  zone  of 
blue  clay  which  underlies  it.  The  latter  is  gen- 
erally mottled  with  red  near  its  contact  with  the 
upper  zone.  Rarely  the  red  clay  extends  en- 
tirely down  to  hard  rock.  Since  the  rocks  of  this 
region,  that  is  east  of  the  lake,  are  almost  en- 
tirely volcanic,  or,  where  sedimentary,  contain 
a  large  proportion  of  volcanic  material,  the  f elds- 
pathic  minerals  are  abundant  and  the  resulting 
clay  contains  a  large  proportion  of  kaolin.  The 
iron-bearing  minerals  are  also  abundant  as  the 
rocks  belong  to  the  basic  igneous  group,  and 
hence  the  brilliant  red  color  of  the  clay  when 
thoroughly  oxidized.  Quartz  occurs  in  only  a 
few  of  the  rocks,  so  that  much  of  the  clay  is 
remarkably  free  from  grit,  tough  and  compact. 
Although  it  is  penetrated  by  numerous  roots 
and  burrowing  insects,  the  absence  of  frost  per- 
mits it  to  remain  more  compact  than  any  surface 
clay  in  higher  latitudes.  Xext  to  the  silt  it  will 
form  by  far  the  hirgest  part  of  the  excavation. 
It  will  make  perfectly  impervious  embankments 
if  some  means  are  taken  to  puddle  it  as  it  is 


deposited,  but  probably  if  simply  dumped  in  the 
bank  it  would  be  pervious  to  water.  When 
water  is  once  thoroughly  incorporated  with  the 
clay,  it  will  remain  indefinitely,  and  the  resulting 
mixture  will  probably  be  more  fluid  than  the 
silt. 

The  clay  on  the  west  side  differs  from  that  on 
the  east  chiefly  in  the  matter  of  color.  At  the 
surface  it  is  almost  black,  but  becomes  a  bluish- 
black  or  gray  a  few  feet  below  the  surface  and 
sometimes  yellow  near  the  rock.  Nearly  all 
of  the  clay  west  of  the  lake  which  will  be  en- 
countered in  excavating  the  canal  is  derived  from 
calcareous  shales  and  sandstones.  These  rocks 
have  originally  contained  a  considerable  pro- 
portion of  volcanic  material,  probably  deposited 
as  fine  dust  while  they  were  being  laid  down, 
and  the  clay  does  not  differ  in  composition  ma- 
terially from  the  red  clay  on  the  east  side.  It 
seems  to  be  considerably  more  pervious  to  water, 
however,  but  this,  as  explained  on  a  previous 
page,  may  be  due  to  the  fact  that,  owing  to  cli- 
matic conditions,  it  is  alternately  thoroughly  dry 
and  wet. 

Soft  Rook. — The  residual  clay  passes  by  im- 
perceptible gradations  downward  into  the  next 
class  of  materials,  which,  for  convenience,  have 
been  grouped  together  as  soft  rock.  The  clay 
represents  the  zone  of  complete  rock  weathering 
in  which  the  original  minerals  are  entirely  al- 
tered, with  the  exception  of  quartz,  and  in  which 
the  original  rock  structure  is  also  in  general  ob- 
literated. The  soft  rock  represents  the  zone  of 
rock  weathering  in  which  the  process  is  only 
partially  completed.  The  most  altered  minerals 
are  entirely  changed  and  the  soluble  constituents 
are  largely  removed,  but  the  structure  of  the 
rock,  and  some  of  the  more  obdurate  minerals 
remain  more  or  less  perfectly  preserved.  The 
material  may  be  soft,  but  is  not  plastic  like  clay. 


156 


NICARAGUA  CANAL  COMMISSION 


It  will  be  readily  understood  that  the  line  sepa- 
rating these  two  divisions  is,  to  a  large  extent, 
arbitrary.  They  are  never  separated  by  a  sharp 
line,  and  it  is  sometimes  a  matter  of  opinion 
where  the  division  should  be  placed.  The  rocks 
generally  weather  inward  from  cracks  which  sep- 
arate the  mass  into  rhomboidal  blocks.  As  the 
weathering  proceeds  suc»ceFsive  concentric  layers 
of  weathered  rock  break  off,  and  if  the  process  is 
not  entirely  complete  a  core  of  fresh  rock  re- 
mains at  the  center.  These  fresh  cores  persist 
longest  in  the  case  of  basalt  and  are  generally 
found  more  or  less  abundant  not  only  in  the  soft 
rock,  but  in  the  residual  clay  as  well,  becoming 
more  abimdant  downward  until  they  merge  with 
the  solid  rock.  While  the  final  product  of  the 
weathering  of  nearly  all  the  rocks  of  the  region 
is  practically  the  same,  mainly  a  tough,  red 
clay,  each  variety  of  rock  has  a  mode  of  disin- 
tegrating and  weathering  which  is,  in  a  measure, 
peculiar  to  itself.  Since  the  original  character 
of  the  rock  remains  to  a  certain  extent  in  the 
zone  of  soft  rock,  the  original  character  and  the 
peculiar  method  of  weathering  become  more  im- 
portant than  in  the  consideration  of  the  residual 
clay. 

In  the  Brito  formation,  the  calcareous  sand- 
stones and  shales  of  the  west  side,  the  bedding 
is  nearly  horizontal,  rarely  dipping  more  than 
15°,  but  the  rocks  are  intersected  bv  numerous 
joints  which  are  more  pronounced  than  the  bed- 
ding planes.  There  are  usually  at  least  two  sys- 
tems of  vertical  joints  and  frequently  more,  so 
that  the  rocks  are  broken  up  into  rhomboidal 
blocks  which  usuallv  var\'^  in  size  with  the  thick- 
ness  of  the  beds.  The  distance  between  the  main 
joints  is  generally  about  the  same  as  the  distance 
between  the  main  bedding  planes.  Only  a  few  of 
the  more  massive  beds  of  sandstone  appear  to  be 
continuous  and  unbroken  by  these  joints.   Much 


of  the  rock  is  a  fine-grained  calcareous  mudstone 
or  non-fissile  shale.  This  is  broken  up  into  small 
rhomboidal  blocks  a  few  inches  in  diameter,  and 
in  the  zone  of  soft  rock  these  are  weathered  in 
such  a  manner  that  concentric  flakes  split  off 
from  the  blocks  and,  when  exposed,  they  crum- 
ble entirely  down  to  the  center.  The  weathering 
is  produced  by  the  leaching  of  the  soluble  con- 
stituents, chiefly  lime,  and  the  decay  of  felds- 
pathic  minerals.  The  disintegration  of  the  rock, 
however,  which  is  due  to  jointing,  is  a  much 
more  marked  feature  than  the  rock  decay.  This 
zone  extends  to  a  very  considerable  distance  be- 
low  the  surface,  but  its  depth  is  dependent 
largely  upon  the  original  character  of  the  rock, 
being  less  in  proportion. to  its  original  massive- 
ness.  This  rock,  so  thoroughly  disintegrated  that 
it  breaks  upon  exposure  into  small  fragments, 
is  the  material  to  which  the  native  name  cascajo 
is  applied.  The  term  is  a  convenient  one  with 
a  perfectly  definite  meaning,  and  should  be 
used,  if  at  all,  with  discrimination.  It  is  prob- 
able that  all  the  material  on  the  west  side  which 
has  been  classed  as  soft  or  disintegrated  rock  can 
be  excavated  with  a  steam-shovel  without  blast- 
ing. The  material  stands  in  natural  slopes  of 
60°  or  more,  and  artificial  slopes  equally  steep 
will  probably  be  entirely  safe. 

The  Machuca  formation  in  its  original  com- 
position is  very  similar  to  the  Brito,  but  it 
weathers  in  a  very  different  manner  owing  to 
the  different  climatic  conditions  on  the  opposite 
sides  of  Lake  Nicaragua.  The  Machuca  sand- 
stone is  intersected  by  numerous  joint  planes, 
but  the  consequent  disintegration  is  much  less 
prominent  than  the  rock  decay,  and  this  has  gen- 
erally gone  so  far  that  the  resulting  product  is 
more  properly  classed  with  the  clay  than  the 
soft  rock.  Although  some  traces  of  the  orig- 
inal rock  structure  remain  within  a  zone  covering 


APPENDIX  II.— GEOLOGIC  REPORT 


157 


the  hard  rock,  it  will  for  all  engineering  pur- 
poses be  treated  as  clay. 

Among  the  volcanic  rocks  of  the  east  side  the 
material  classed  as  soft  rock  is  quite  different 
from  the  cascajo  above  described.  It  may  be 
considered  under  three  varieties;  first,  that  de- 
rived from  basalt;  second,  from  dacite;  and, 
third,  from  volcanic  sandstones  and  conglom- 
erates. 

The  basalt  is  fii*st  intersected  by  joints  which 
break  it  up  into  large  rhomboidal  blocks.  From 
these  joints  the  weathering  progresses  inward, 
and  successive  layers  are  separated  from  the  core 
of  fresh  rock  within.  These  cores  remain  as 
boulders,  and,  as  already  stated,  are  found  in  the 
zone  of  residual  clay  as  well  as  in  that  of  the 
soft  rock.  The  basalt  varies  considerably  in 
texture.  The  upper  and  lower  surfaces  of  a  lava 
flow  are  usually  more  or  less  vesicular,  and  the 
basalts  of  this  region  appear  to  be  largely  lava 
flows.  These  vesicular  portions  are  more  readily 
penetrated  by  the  percolating  waters  from  the 
surface  and  their  decay  is  correspondingly  more 
rapid,  hence  it  often  happens  that  the  central 
compact  portion  of  a  lava  flow  will  be  marked 
by  a  nearlv  continuous  layer  of  fresh  boulders, 
while  the  vesicular  portions  above  and  below  will 
be  thoroughly  decayed  and  few  if  any  boulders 
will  remain.  The  basalt  is,  when  fresh,  a  hard 
black  rock  which  rings  under  the  hammer,  and 
is  altered  to  a  soft,  bluish-gray  or  rusty  yellow 
material  which  can  be  readily  cut  with  a  knife, 
but  in  which  the  original  structure  of  the  rock 
is  more  or  less  distinctly  preserved.  This  ma- 
terial is  not  plastic  and  is  more  permeable  to 
water  than  the  residual  clay. 

The  dacite  is  originally  a  very  firm  rock  which 
generally  weathers  from  the  surface  downward 
rather  than  from  joints  toward  the  center  of 
rhomboidal  blocks.     The  soft  rock  derived  from 


its  decay,  therefore,  is  more  imiform  in  structure 
than  that  derived  from  the  basalt.  It  rarely 
contains  residual  boulders  of  the  fresh  rock,  and 
presences  much  more  perfectly  the  original  struc- 
ture of  the  rook  from  which  it  is  derived.  It 
forms  a  pink  or  gray  material  soft  enough  to  be 
cut  with  a  knife,  in  which  the  constituent  min- 
erals can  be  readily  diatinguished,  but  in  which 
all  minerals  except  the  quartz  are  thoroughly 
decayed. 

The  volcanic  sandstones  and  conglomerates 
weather  somewhat  like  the  dacite.  There  is  a 
regular  downward  increase  in  amount  of  decay 
and  all  parts  of  the  rock  weather  equally,  the 
fine  matrix  as  well  as  the  large  pebbles.  The 
resulting  material  retains  perfectly  the  original 
structure  of  the  rock,  the  pebbles  being  distinct 
and  in  their  original  shape,  but  the  whole  mass 
so  soft  that  it  can  be  readily  cut,  and  in  some 
cases  it  might  well  be  classed  as  clay. 

The  three  classes  of  materials  above  described 
— alluvium,  residual  clay  and  soft  rock — should 
be  considered  as  earth  in  making  estimates  for 
excavation.  The  soft  rock,  however,  may  re- 
quire some  blasting,  particularly  toward  the 
bottom  and  where  it  contains  very  large  boul- 
ders. It  will  stand  w^ith  much  steeper  slopes 
than  the  alluvium  and  clay  and  will  be  less 
liable  to  slip.  Xot  being  plastic  it  will  also  sup- 
port a  heavier  load  and  hence  may  be  relied' upon 
for  foundations  where  the  weight  of  the  struc- 
ture is  not  excessive.  For  these  reasons  it  seems 
desirable  to  make  the  distinction  between  clay 
and  soft  rock  wherever  possible.  It  should  be 
clearly  understood,  however,  that  when  consid- 
ered with  reference  to  cost  of  excavation  the  ma- 
terial classed  as  soft  rock  must  be  regarded  as 
earth.  It  will  be  somewhat  more  difficult  to 
handle  than  the  residual  clay,  chiefly  by  reason 
of  the  greater  number  of  boulders  which  it  con- 


158 


NICARAGUA  CANAL  COMMISSION 


tains,  but  it  will  probably  be  handled  with  con- 
siderably less  difficulty  than  glacial  drift,  boulder 
till  or  hardpan. 

Hard  Rock. — So  extensive  has  been  the  rock 
weathering  in  this  region  that  fresh  rock  rarely 
appears  at  the  surface,  and  in  most  cases  none 
has  been  reached  at  the  depths  penetrated  by 
the  diamond  drill.  Bv  fresh  rock  is  here  meant 
one  in  which  the  constituent  minerals  have  suf- 
fered no  alteration.  The  residual  boulders  of 
basalt,  however,  are  surprisingly  fresh,  and  even 
when  examined  under  the  microscope  it  is  found 
that  the  constituent  minerals  have  been  altered 
scarcelv  at  all.  Bv  hard  rock  is  meant,  in  this 
connection,  therefore,  not  a  rock  which  is  un- 
altered, but  one  which  is  hard  enough  to  require 
blasting  for  excavation.  In  practice  the  line 
between  hard  and  soft  rock  was,  in  general, 
placed  at  the  point  where  the  diamond  drill  be- 
gan to  yield  a  fairly  continuous  core.  This  cri- 
terion is  open  to  objection,  since  a  very  soft  rock 
will  yield  a  core  if  it  is  perfectly  homogeneous, 
while  a  .very  hard  rock  will  not  core  if  some  por- 
tions are  harder  than  others.  The  hard  por- 
tions choke  in  the  bit  and  grind  up  the  softer 
portions,  particularly  if  the  rock  is  intersected 
by  joints. 

As  there  is  a  gradual  transition  from  residual 
clay  to  soft  rock,  so  there  is  a  similar  gradual- 
transition  from  soft  rock  to  hard  rock,  and  the 
separation  of  the  two  classes  of  material  is,  to  a 
certain  extent,  arbitrary.  In  some  cases  the 
residual  boulders  become  more  and  more  abund- 
ant until  they  pass  into  a  massive  rock  inter- 
sected by  few  insignificant  joint  planes.  In 
other  eases,  as  in  that  of  dacite,  the  rock  be- 
comes very  gradually  harder  by  reason  of  the 
less  altered  condition  of  the  constituent  minerals 
until  it  may  be  regarded  as  hard  rock.  It  is 
safe  to  predict  that  the  surface  separating  the 


two  will  nowhere  be  found  so  regular  as  it  is 
represented  on  the  sections. 

The  rocks  of  the  region  have  been  rather  fully 
described  in  a  previous  part  of  this  report,  and 
but  little  further  remains  to  be  said  concerning 
them.  The  primary  classification  as  sedi- 
mentary and  igneous  rocks  is  of  considerable  im- 
portance to  the  engineer  and  also  the  particular 
manner  in  which  each  class  of  rocks  weathers. 

The  heavv  dark-colored  basic  rocks  which  are 

»,■ 

grouped  together  as  trap  are  the  hardest  rocks 
which  will  be  encountered  on  the  line  of  the 
canal.  They  are  admirably  adapted  for  con- 
crete work  but  would  shatter  in  blasting  and 
hence  probably  could  not  be  taken  out  in  blocks 
of  sufficient  size  for  use  in  a  rock  fill  dam  as  the 
Canal  Company  proposed  to  build  at  Ochoa. 
They  would  also  be  poorly  adapted  for  use  where 
dimensional  blocks  were  required  on  account  of 
the  cost  of  quarrying  and  dressing. 

Xext  in  hardness  is  the  dacite.  This  is 
tougher  than  the  trap  and  probably  would  not 
shatter  in  blasting,  so  that  blocks  of  any  size 
required  might  be  taken  from  the  cuts.  It 
might  also  be  quarried  in  dimensional  blocks  and 
dressed  with  comparative  ease.  Quarrying, 
however,  would  be  expensive  by  reason  of  the 
great  depth  of  residual  and  decayed  material 
which  evervwhere  covers  the  hard  rock.  Its 
rapid  weathering,  noted  above,  would  render  it 
a  decidedly  inferior  building  stone.  The  vari- 
ous sedimentarv  rocks  diflFer  widelv  in  hardness 

•■■  »■ 

and  show  considerable  variation  even  in  a  single 
formation.  In  a  general  way  the  hardness  de- 
creases in  the  following  order — Machuca  sand- 
stone, volcanic  sandstone  (Ochoa),  Brito  sand- 
stone, basaltic  tuff  (Eastern  Divide).  This  order 
apj)lies  only  to  the  average  hardnoss,  and  cer- 
tain l)e(ls  could  be  selected  from  the  several 
formations  which  would  occupy  a  different  order. 


APPENDIX   II.— GEOLOGIC   REPORT 


159 


A  matter  of  considerable  importance  to  the 
engineer  is  the  specific  gravity  of  the  rock  with 
which  he  has  to  deal,  especially  that  which  is 
used  for  construction  purposes. 

The  following  table  gives  the  specific  gravity 
and  weight  per  cubic  foot  of  the  more  important 
varieties  of  rock  on  the  canal  lines.  The  deter- 
minations were  made  by  Mr.  George  Steiger  in 
the  laboratory  of  the  U.  S.  Geological  Survey. 
The  material  was  allowed  to  stand  in  water  for 
several  hours  before  weighing,  so  that  the  values 
given  in  the  table  correspond  with  those  which 
would  be  found  if  freshly  excavated  material 
were  examined.  The  specific  gravities  are 
somewhat  lower  than  would  be  found  for  thor- 
oughly air-dried  material.  The  weights  per 
cubic  foot,  however,  exceed  those  for  dried  ma- 
terial by  the  weight  of  the  water  which  a  cubic 
foot  of  the  dried  material  would  absorb. 

The  average  values  given  by  Trautwine  for 
four  varieties  of  rock  are  added  to  the  table  for 
comparison. 


No.  1  Andesite  forming  the  hills  north  of  the 
Rio  Grande  valley  about  8  miles  from  Brito,  is 
a  compact  crystalline  rock  which  will  prob- 
ably be  found  the  best  available  material  for 
the  construction  of  breakwaters  at  Brito  harbor. 
Its  density  is  slightly  greater  than  that  of  the 
average  granite. 

Xos.  2  and  3  represent  a  fair  average  of  the 
dacitc  in  the  Eastern  Divide.  This  is  the  light- 
est rock  on  the  canal  line,  and  in  that  respect  is 
inferior  to  the  traps  as  material  for  rock-fill 
dams,  where  high  specific  gravity  is  of  special 
importance.  It  is,  however,  the  rock  which 
would  be  chiefly  employed  for  that  purpose  if 
the  Alenocal  route  were  adopted. 

No.  4  is  a  dacite  encountered  at  Lower  Ochoa 
which  is  more  compact  and  much  darker  in  color 
than  the  dacite  of  the  Eastern  Divide.  The 
presence  of  the  dark  iron  silicates  gives  it  a 
rather  high  specific  gravity,  though  it  is  lower 
than  that  of  the  basalts. 

Nos.  5,  6,  7  and  8  represent  the  dark  igneous 


Name.  Locality.  S.  G. 

1.  Andesite Rio  Grande,  hole  3,  37' 2.75 

2.  Dacite Eastern  Divide,  hole  3,  109' 2.26 

3.  Dacite Eastern  Divide,  hole  4,  140' 2.30 

4.  Dacite Lower  Ochoa,  hole  3,  33' 2.63 

5.  Olivine  free  Basalt Sarapiqui  hills,  spec.  170 2.77 

6.  Olivine  Basalt San  Francisco  hills,  spec.  168 2.88 

7.  Olivine  Basalt Upper  Ochoa,  hole  9,  83' 2.88 

8.  Hypersthene  Basalt San  Carlos  Hills,  spec.  44 2.73 

9.  Sandstone Machuca  creek,  spec.  139 2.67 

10.  Sandstone Las  Lajas,  hole  1,  16' 2.67 


Average  Wt.  |>er 
8.  O.       cu.  ft. 


I 

i 

1 


2.28 


]•  2.81 


I 


2.6 


171 
141 
143 
164 
173 
180 
180 
170 
166 
166 


AVEKA(.E8  (ilVEN  HV  TRAUTWINE. 

Average  Wt.  i)er 

Name.                                   S.  O.  cu.  ft. 

Basalt 2.9  181 

Granite*  ..'. 2.72  170 

Limestone   2.7  1  C>9> 

Sandstone 2.41  151 


rocks,  varieties  of  basalt,  classed  together  as  trap. 
Their  average  specific  gravity  is  slightly  under 
the  average  given  by  Trautwine  for  basalt. 
These  are  the  rocks  which  will  be  chiefly  relied 
upon  for  structural  purposes  if  th(»  Lull  route  is 
selected. 


160 


NICARAGUA  CANAL  COMMISSION 


Xo8.  9  and  10  represent  average  samples  of 
the  sandstone  beds  in  the  Machuca  and  Brito 
formations.  Their  specific  gravity  is  somewhat 
above  the  average  for  sandstone  given  by  Traut- 
wine. 

FACTORS  DETERMINING  RELATIVE 
COST  OF  EXCAVATING  HARD 

ROCK. 

In  considering  the  cost  of  excavating  the  ma- 
terial classed  as  hard  rock  on  the  line  of  the 
canal,  two  elements  of  cost  which  need  to  be  con- 
sidered here  as  elsewhere  are,  first,  the  drilling, 
and,  second,  the  blasting.  These  two  elements 
may  or  may  not  vary  in  the  same  direction  in  dif- 
ferent rocks,  since  they  depend  upon  different 
physical  properties.  The  relative  ease  of  drilling 
depends  on  the  hardness  of  the  constituent  min- 
erals, on  the  character  and  amount  of  cements  by 
which  they  are  bound  together,  and,  to  some  ex- 
tent, on  their  density;  in  other  words,  on  their 
relative  induration.  The  relative  ease  of  blast- 
ing, on  the  other  hand,  depends  on  the  cement 
which  binds  the  particles  together,  or  their  co- 
hesion; on  the  original  or  secondary  planes  of 
weakness  in  the  rock,  such  as  bedding  planes, 
flowage  surfaces,  fault  fractures,  shrinkage 
joints,  compression  joints,  etc.;  also  on  the 
presence  or  absence  of  grain  in  the  rock.  It  is 
thus  seen  that  many  variables  enter  into  the 
^problem.  An  idea  as  to  the  cost  of  excavation 
can  best  be  reached  perhaps  by  arranging  the 
various  rocks  to  be  excavated  in  the  Nicaragua 
Canal,  together  with  other  known  types,  in  a 
scale  showing  relatively  their  induration,  which 
may  be  regarded  as  determining  the  cost  of  drill- 
ing, and  their  toughness,  which  determines  the 
cost  of  blasting. 

It  should  be  noted  that  the  arrangement  is 
based  on  the  character  of  the  various  classes  of 


rocks  as  they  actually  occur  in  this  region  in  a 
more  or  less  disintegrated  and  weathered  condi- 
tion. If  the  rocks  were  entirely  unaltered  their 
relative  position  in  the  scale  might  be  quite  dif- 
ferent from  that  given. 


Relative  Induration. 

Basaltic  tuff. 


Brito  sandstone. 

Limestone  of  Chi- 
cago drainage  canal. 


Volcanic  sandstone. 
Machuca  sandstone. 
Dacite. 

Basalt.    • 


Granite  (unaltered). 


1 
2 
3 
4 
5 
6 
7 
8 
9 
10 

11 
12 
13 
14 
15 
16 
17 
18 
19 
20 


Relative  Toujrbness. 

Basaltic  tuff. 


Brito  sandstone. 


Machuca  sandstone. 

Limestone  of  Chi- 
cago drainage  canal. 

Volcanic  sandstone. 


Basalt. 
Dacite. 


Granite  (unaltered). 


The  basaltic  tuff  is  at  the  bottom  of  the  scale 
both  in  induration  and  toughness,  and  there  may 
perhaps  be  some  question  as  to  the  propriety  of 
placing  it  in  the  class  of  hard  rock. 

The  Brito  sandstone  is  low  in  the  scale  of 
induration  because  it  is  composed  largely  of  soft 
minerals  bound  together  by  a  calcareous  cement. 
It  is  low  in  the  scale  of  toughness  because  it  is 
intersected  by  well  marked  bedding  planes  and 
also,  to  a  greater  depth  than  the  excavation  will 
reach,  by  many  joint  planes. 

The  Machuca  sandstone  is  low  in  the  scale  of 
toughness  because  of  its  bedding  and  joint 
planes,  and  rather  high  in  induration  because  of 


APPENDIX  II.— GEOLOGIC   REPORT 


161 


the  considerable  proportion  of  quartz  which  it 
contains. 

Dacite  and  basalt  are  rather  high  both  in  the 
scale  of  relative  induration  and  relative  tough- 
ness because  of  the  hardness  and  cohesion  of 
their  constituent  minerals  and  the  scarcity  of 
primary  or  secondary  planes  of  weakness  in  the 
rock.  Joint  planes  are  somewhat  more  abimd- 
ant  in  the  basalt  than  in  the  dacite,  otherwise 
the  former  would  be  higher  in  the  scale  of  tough- 
ness than  the  latter. 

It  will  be  readily  understood  that  the  above 
table  represents  conclusions  arrived  at,  not  by 
any  exact  methods,  but  by  a  careful  consideration 
of  the  physical  characteristics  of  the  rocks  in 
question  and  an  attempt  to  assign  to  these  vari- 
ous characteristics  their  proper  weight  as  affect- 
ing the  result.  Too  much  importance  should 
not,  therefore,  be  attached  to  the  conclusions 
there  expressed,  and  it  is  quite  possible  that 
actual  experience  may  materially  alter  the  rela- 
tive positions  which  the  various  rocks  may  oc- 
cupy in  the  table. 

CHAKACTEK  OF  DATA  ON  WHICH 

GEOLOGIC  SECTIONS  AKE 

BASED. 

The  facts  on  which  are  based  the  conclusions 
stated  in  this  report  and  on  the  various  sections 
furnished  to  the  engineers  for  use  in  making  esti- 
mates are  derived  from  three  sources:  first,  bor- 
ings made  under  the  direction  of  the  present 
Commission ;  second,  the  examination  of  surface 
outcrops  and  natural  sections;  and,  third,  records 
of  borings  made  by  the  Canal  Company. 

Boeing  Operations. — The  outfit  employed  in 

the  boring  operations  recently  carried  on  under 

the  direction  of  the  Commission   consisted  of 

two  parts:  the  Pierce  well-driving  outfit,  and  the 
11 


diamond  drill.  Bv  means  of  the  former  a  two- 
inch  casing  was  driven  down  through  the  uncon- 
solidated residual  or  alluvial  material  at  the  sur- 
face into  the  soft  rock  and  in  some  cases  to  the 
hard  rock.  Tlie  diamond  drill  w^as  then  set  up 
and  the  section  continued  to  any  depth  required. 
During  the  process  of  driving  the  pipe,  samples 
of  the  material  passed  through  were  taken  at 
frequent  intervals  and  a  complete  suite  pre- 
served.  All  the  core  obtained  bv  means  of  the 
diamond  drill  has  been  preserved  and  arranged 
in  the  order  in  which  it  was  taken.  Wherever 
the  rock  failed  to  core,  the  material  brought  up 
by  the  water  was  collected  and  samples  pre- 
served. Four  hundred  drill  sections  Avere  ob- 
tained in  this  manner,  having  an  aggregate 
length  of  12,337  feet.  These  sections  are  dis- 
tributed as  follows:  At  the  La  Flor  dam  site 
four  sections,  with  a  total  length  of  528  feet; 
Brito  harbor,  thirty-nine,  with  a  total  length  of 
1773  feet;  on  the  excavation  line  near  the  end  of 
the  Rio  Grande  gorge  and  at  Las  Lajas,  eleven 
sections  with  a  total  length  of  668  feet;  at  the 
various  dam  sites  and  embankment  lines  on  the 
east  side,  101  sections,  ^vith  a  total  length  of 
4590  feet;  in  the  channel  of  the  San  Juan  river, 
239  sections,  with  a  total  length  of  4018  feet; 
and  in  the  Eastern  Divide,  four  sections,  with  a 
total  length  of  759  feet. 

Surface  Examinations. — The  value  of  the 
surface  examinations  varied  somewhat  widelv. 

ft' 

In  some  portions  of  the  region  outcrops  are  so  in- 
frequent that  little  information  concerning  the 
character  of  the  rocks  could  be  secured  bv  such 
an  examination  and  it  was  therefore  devoted 
chiefly  to  the  physiographic  features.  Enough 
residual  boulders  were  usuallv  found  in  the  clav 
at  the  surface  to  determine  the  character  of  the 
underlying  rock,  although  the  limits  of  the  vari- 
ous formations  could  rarelv  be  determined  with 


162 


NICARAGUA  CANAL  COMMISSION 


accuracy  by  this  means.  West  of  Lake  Nicara- 
gua the  iiifonnation  to  be  obtained  by  surface 
examination  is  much  greater  than  in  the  eastern 
division.  This  is  chiefly  due  to  the  much  great- 
er depth  of  the  residual  mantle  in  the  latter 
than  in  the  former  region.  Also  the  sea  and 
lake  cliffs  and  the  stream  channels  give  tolerably 
good  geological  sections  which  afford  much  in- 
formation concerning  the  character  of  the  under- 
lying rocks. 

Records  of  the  Canal  Company's  Borings. 
— The  records  of  borings  made  by  the  Canal 
Company  are  the  least  satisfactory  of  the  three 
sources  of  information.  None  of  this  work 
appears  to  have  been  done  by  men  trained  in 
making  geological  observations.  The  records 
are  very  meager  and  incomplete.  There  is  no 
harmony  in  the  terminology  employed,  and  with- 
out the  specimens  it  is  generally  impossible  to 
gain  much  information  from  these  records. 
Although  many  borings  were  made,  in  most  cases 
they  were  not  carried  to  a  sufficient  depth  to 
furnish  the  definite  information  required.  In 
most  cases,  except  on  the  Eastern  Divide,  they 
merelv  furnish  a  minimum  measure  of  the  un- 
consolidated  surface  material.  When  rock  is 
reported  there  is  always  a  question  whether  the 
rock  is  not  simply  a  boulder.  In  a  few  cases  the 
records  appear  to  be  erroneous,  perhaps  through 
mistakes  in  transcribing  them.  These  mistakes, 
wherever  thev  have  been  detected,  have  been 
uniformly  unfavorable  to  the  Canal  Company's 
plans  so  that  they  cannot  be  regarded  as  inten- 
tional. They  serve,  however,  to  cast  a  shade  of 
doubt  upon  all  the  records  and  thus  detract 
materially  from  any  value  which  they  might 
otherwise  have.  The  most  svstematic  work 
done  by  the  Canal  Company  was  on  the  Eastern 
Divide  and  the  La  Flor  dam  site.  The  records 
at  these  two  places,  however,  would  have  been 


quite  unintelligible  without  the  additional  work 
done  bv  the  Commission. 

GEOLOGIC  DETAILS. 

Western  Division. — Beginning  wuth  the  Pa- 
cific terminus  the  various  canal  routes  will  be 
taken  up  and  the  geology  of  the  immediate  lo- 
calities concerned  will  be  descrilx?d  in  some 
detail.  This  description  is  given  wuth  special 
reference  to  the  needs  of  the  engineers.  Natur- 
ally some  repetition  is  involved  of  matter  con- 
tained in  the  first  part  of  this  report,  but  a  re- 
iteration of  some  of  the  more  important  geo- 
logical facts  may  be  made  with  advantage. 

La  Flor  Dam  Site. — Section,  Fig.  1,  Plate 
XYII. — The  boring  done  by  the  Canal  Com- 
pany at  the  proposed  La  Flor  dam  site  was  more 
thorough  and  systematic  than  at  any  other 
point  on  the  line.  Only  four  holes,  therefore, 
were  put  down  by  the  Commission,  and  these 
were  for  the  purpose  of  verifying  the  results 
obtained  by  the  Canal  Company  and  interpreting 
their  records.  As  a  result  of  this  combined  work 
the  conditions  at  La  Flor  may  be  regarded  as 
very  perfectly  known.  The  old  river  valley  at 
this  point  has  a  depth  of  fifty  feet  below  sea 
level,  or  about  ninety  feet  below  the  present 
flood-plain.  The  section  of  the  valley  as  devel- 
oped by  the  borings  is  that  which  would  be  pro- 
duced by  the  continuation  of  the  present  slopes 
with  normal  curves  below  the  margm  of  the  allu- 
vium. The  matenal  forming  the  sides  and  bot- 
tom of  this  old  vallev  beneath  the  alluvium  is 
precisely  the  same  as  that  exposed  in  the  hills 
on  either  side.  It  is  a  calcareous  shale  contain- 
ing numerous  layers  of  fine  sandstone.  This 
material  has  been  somew^hat  fullv  described  in  a 
previous  part  of  this  report.  The  rock  is  in- 
tersected by  numerous  joints  which  break  it  up 
into     small     rhomboidal     blocks.     In    drilling 


APPENDIX   II.— GEOLOGIC   REPORT 


163 


through  such  material  very  little  continuous 
core  is  obtained  since  the  harder  sandy  layers 
tend  to  choke  the  bit  and  grind  up  the  softer 
portions.  The  material  which  comes  to  the  sur^ 
face  with  the  water  then  very  closely  resem- 
bles clay.  These  conditions  have  led  to  the 
designations  previously  applied  to  this  material, 
such  as  "  clav  and  rock  in  lavers;  "  **  rock  with 
clay  seams;"  "  argellite  with  clay  seams;" 
"  layers  of  stones  in  clay,"  etc.  Much  of  the 
material  has  been  classed  as  telpetate  and  cascajo, 
Telpetate  or  tepetate  is  a  term  used  in  Mexico 
and  other  Spanish- American  countries  for  a  soft, 
friable,  chalky  gray  or  yellow  rock,  formed  by 
precipitation  from  calcareous  water,  i.  e,  tufa, 
or  from  partial  solidification  of  volcanic  ash  and 
mud,  i.  e.  tuff. 

Talpeiate  is  thus  described  by  Levy:'  "If 
a  cloud  of  ashes  be  suspended  in  the  air  it  is 
readily  seen  that  the  heavier  particles  are  the 
first  to  obey  the  attraction  of  gravity  and  that 
the  lighter  are  the  last  to  reach  the  surface. 
Moreover,  if  the  heavier  portions  are  formed  of 
a  soft  material  or  are  in  a  state  of  semi-fusion,  it 
is  known  that  they  will  become  round  before 
they  reach  the  earth.  In  Nicaragua  the  name 
talpetate  or  talpuja  is  given  to  these  layers  of 
ashes.  It  is  a  species  of  fine-grained  conglom- 
erate formed  of  small,  smooth  and  round  balls, 
partially  cemented  by  a  finely  powdered  tuff. 
In  some  places  the  ash  does  not  contain  soft 
material  and  then  it  is  simply  deposited  in  the 
order  of  increasing  density;  also  it  is  without 
cohesion  and  does  not  contain  the  small  balls." 

Nothing  which  would  answer  this  description 
occurs  at  La  Flor,  and  it  is  clearly  a  misnomer  to 
apply  the  term  to  this  more  or  less  disintegrated 
rock,  which  is  distinctly  of  sedimentary  origin, 

1  Notas  Geographicas  y  Economicas  sobra  la  Repnblica 
de  Nicaragua,  Pablo  Levy,  Paris,  1873,  p.  145. 


and  contains  only  a  relatively  small  proportion 
of  volcanic  material.  Cascajo,  on  the  other 
hand,  is  properly  applied  to  the  surface  rock  in 
the  vicinitv  of  La  Flor.  The  term  is  defined 
by  Levy  as  follows: 

**  In  Nicaragua  the  name  laja  is  given  to  lava ; 
also  the  layers  of  stratified  tfap  are  called  lajas, 
and,  in  general,  any  rock  which  is  distinctly  and 
evenly  bedded.  When  lajas,  that  is  bedded 
rocks  of  any  kind,  are  disintegrated,  forming 
small  easily  di^asible  fragments,  this  disinte- 
grated material  is  called  cascajo." 

While  the  rock  which  forms  the  bottom  and 
sides  of  the  old  river  vallev  at  La  Flor  is  more 
or  less  disintegrated  and  breaks  up  into  small 
blocks  when  it  is  removed,  it  is  nevertheless 
abundantly  competent  to  sustain  any  pressure  to 
which  it  would  be  subjected  by  a  structure  such 
as  the  proposed  La  Flor  dam.  It  would,  there- 
fore, be  necessary  in  constructing  a  masonry 
dam  at  this  point  merely  to  excavate  the  allu- 
vium down  to  the  bottom  of  the  old  channel, 
fifty  feet  below  sea  level.  On  the  sides  of  the 
valley  above  the  present  alluvium,  and  perhaps 
a  sh9rt  distance  below  it,  it  would  of  course  be 
necessarv  to  excavate  a  few  feet  of  residual 
sandy  clay  and  thoroughly  disintegrated  rock  in 
order  to  secure  a  satisfactory  foundation.  In 
the  deeper  portions  of  the  valley,  however,  the 
transition  from  alluvium  to  rock  appears  to  be 
comparatively  sharp  and  the  residual  material, 
if  present,  is  very  thin. 

Rio  Grande  Dam  Site, — Section,  Fig.  2,  Plate 
XVn.— The  two  Variants  I  and  III  of  the 
Childs  route  between  Lake  Nicaragua  and  the 
Pacific  involve  the  location  of  a  dam  and  locks  at 
some  point  in  the  upper  portion  of  the  Rio 
Grande  valley.  The  site  for  such  a  dam  having 
greatest  natural  advantages  appears  to  be  at 
Buen  Retiro,  about  nine  miles  from  the  lake. 


164 


NICARAGUA   CANAL  COMMISSION 


The  soetion  referred  to  above  sliows  the  geologi- 
cal conditions  at  this  point.  The  hill  which  occu- 
pies the  center  of  the  valley  is  composed  of  cal- 
careous shale  more  or  less  disintegrated,  but  suf- 
ficiently firm,  however,  for  foundation  purposes. 
The  saddle  north  of  this  hill  was  formerlv  a 
channel  of  the  river,  the  rock  bottom  of  which 
is  about  fifty  feet  above  sea  level.  This  is  con- 
siderably below  the  present  bed  of  the  river  and 
is  approximately  the  same  depth  as  the  old  river 
channel  which  is  now  partially  occupied  by  the 
Rio  Grande.  The  foundations  of  the  dam  at 
this  point  would,  therefore,  be  about  fifty  feet 
above  sea  level  and  comparatively  little  silt 
would  have  to  be  excavated  to  place  the  foun- 
dations upon  rock.  The  long  gentle  slopes  of 
the  hills  south  of  the  valley  are  covered  by  a 
tliin  layer  of  residual  clay,  under  which  is  more 
or  less  disintegrated  rock,  passing  downward  at 
an  unknown  depth  into  solid  rock.  This  ma- 
terial would  afford  suitable  foundations  for  locks 
or  other  structures.  The  material  filling  the  old 
channel  in  the  saddle  is  compacted,  sandy  clay 
and  sand  similar  to  that  which  partly  fills  the 
upper  portion  of  the  Eio  Grande  channel.  At 
some  point  beneath  this  silt  is  the  contact  of  the 
Brito  shale  and  the  underlying  andesite.  The 
shale  appears  to  dip  away  from  the  andesite  as 
though  it  had  been  tilted  up  by  the  intrusion  of 
the  igneous  mass.  The  andesite  forming  the 
hill  immediately  north  of  the  dam  site  will  af- 
ford a  convenient  supply  of  excellent  rocks  for 
the  construction  of  dams  and  controlling  works 
at  this  point. 

Brito, — The  borings  made  by  the  Canal  Com- 
pany on  the  site  of  the  proi>osed  Brito  harbor 
and  shown  on  the  published  map  which  accom- 
panies the  report  of  the  Canal  Board  of  1895, 
indicate  the  presence  of  a  rock  ledge  a  short 
distance  below  the  surface,   extending  from  a 


point  near  the  beach  about  2000  feet,  north  30° 
east,  up  the  valley  of  the  Eio  Grande.  In  order 
to  determine  the  extent  of  this  ledge  thirty- 
eight  holes  were  drilled,  their  location  being 
shown  on  the  accompanying  map,  Plate  VII. 
These  holes  were  put  down  to  depths  between 
forty-five  and  forty-eight  feet  below  high  tide 
of  April  20,  1S98.  Bock  was  found  in  six  of 
these  holes  but  not  at  the  depth  or  in  the  posi- 
tions indicated  by  the  previous  drilling.  The 
form  of  the  rock  surface  developed  by  these  bor- 
ings is  shown  by  means  of  contour  lines  on  the 
map.  It  will  be  noticed  that  the  rock  occurs 
only  near  the  northwestern  margin  of  the  Rio 
Grande  valley.  The  prevailing  direction  of  the 
wind  along  the  beach  is  such,  that  the  sand  is 
drifted  toward  the  western  margin  of  the  valley, 
and  the  lower  portion  of  the  Rio  Grande  is  con- 
stantly crowded  over  to  this  side  of  its  valley  and 
for  a  short  distance  back  from  its  mouth  is  cut- 
ting  the  cliff  which  forms  the  northwestern  head- 
land. By  cutting  away  the  base  of  the  cliff  the 
river  appears  to  have  formed  a  narrow  shelf  on 
the  side  of  the  old  valley  where  the  rock  is  a 
comparatively  short  distance  below  the  surface. 
Portions  of  the  rock  have  been  cut  away  to  a 
considerable  depth,  but  two  ledges  formed  by 
harder  beds  in  the  sandstone  extend  out  into  the 
valley  as  shown  by  the  contours.  These  are 
similar  to  the  ledge  which  projects  from  the  ex- 
treme outer  point  of  the  headlanfl  except  that 
their  surface  is  somewhat  lower.  Southeast- 
ward from  this  rock  shelf  the  old  valley  extends 
to  the  southeastern  margin  of  the  Rio  Grande 
flood-plain,  and  it  is  probable  that  no  rock  would 
be  encountered  in  this  direction  to  within  a  short 
distance  of  the  margin  of  the  valley.  Hence  a 
harbor  might  be  located  at  any  point  between 
the  headlands  with  little  danger  of  encountering 
rock  in  excavation.     The  material  filling  the 


NICARAGUA  CANAL  COMMISSION 


BRITO    HARBOR 

showing  location  of  borings 

made  by  '\yi^)\ 

US.  NICARAGUA  CANAL  COMMISSION  J  ( 
1898. 

SCALE 

Location  of  Borings 
o  Depth  of  hole  below  Mean  "fide 

•  Depth  Tc  rocK  below  Mean  Tide 
Contours  ofrocK  sui'face  below  MeaoTide 


MAP  OF  BRITO  H* 


APPENDIX  2,  PLATE  VII 


IG  DEPTH  TO  ROCK. 


APPENDIX  II.— GEOLOGIC  REPORT 


165 


old  valley  consists  entirely  of  sand  near  the 
present  beach.  A  short  distance  back  from  the 
beach'  the  sand  is  overlain  by  fine  alluvial  silt 
which  increases  in  thickness  up  the  valley  and 
forms  the  banks  of  the  present  Rio  Grande 
channel.  The  greatest  thickness  of  the  fine  allu- 
vium is  perhaps  thirty  or  forty  feet  at  a  distance 
of  several  miles  from  the  coast.  Below  this 
the  greater  portion  of  the  material  filling  the  old 
river  valley  is  sand  with  more  or  less  clay  silt. 

In  the  construction  of  the  harbor  at  Brito  a 
large  amount  of  stone  will  be  required  for  break- 
waters, etc.  The  character  of  the  rock  in  the 
headlands  on  either  side  of  Brito  has  already 
been  described.  That  forming  the  northwest 
headland  is  thin  bedded  sandstone  and  shale  in- 
tersected by  many  joints.  It  is,  therefore,  not 
suitable  for  the  construction  of  breakwaters. 
The  limestone  forming  the  southeast  headland 
can  be  readily  quarried  in  blocks  of  any  desired 
size  and  will  doubtless  be  employed  until  the 
supply  is  exhausted.  The  next  most  convenient 
source  of  supply  is  in  the  hills  north  of  the  Rio 
Grande  valley  at  Buen  Retiro.  The  rock  here 
is  andesite,  a  dark,  compact,  crystalline  rock 
with  high  specific  gravity,  2.75,  which  can  be 
quarried  in  any  sized  blocks  required.  The 
residual  clay  covering  the  hard  rock  is  compara- 
tively thin,  so  that  quarries  can  be  opened  with 
little  dead  work. 

Excavation  LineSy  Childs  Eoute,  Lake  Nica- 
ragua to  Pacific  Ocean. — Numerous  holes  were 
put  down  bv  the  Canal  Company,  chiefly  with 
the  earth  auger,  between  Las  Lajas  and  the  head 
of  the  Rio  Grande  flood-plain.  The  classifica- 
tion of  materials  for  this  portion  of  the  line  has 
been  based  largely  upon  the  records  of  these 
holes,  supplemented  by  one  hole  put  down  on 
the  lake  shore  at  Las  Lajas  and  by  an  examina- 
tion of  the  surface  conditions  in  the  vicinity  of 


the  line.  The  underlying  rock  is  the  Brito  for- 
mation, which  has  been  already  fully  described. 
That  part  of  the  formation  which  reaches  the 
surface  from  a  point  a  short  distance  west  of  the 
lake  to  the  site  of  the  Rio  Grande  dam,  consists 
largely  of  argillaceous  shales  containing  fewer 
beds  of  sandstone  than  the  portions  of  the  for- 
mation which  are  exposed  on  the  lake  shore  and 
on  the  Pacific  coast.  The  rock  is  everywhere 
deeply  disintegrated,  and  the  line  between  the 
materials  classed  as  disintegrated  rock  and  as 
hard  rock  is  difficult  to  draw,  since  the  passage 
from  one  class  of  materials  to  the  other  is  gen- 
erally gradual.  In  the  classification  represented 
on  the  section  the  effort  has  been  made  to  draw 
this  line  at  the  bottom  of  the  material  which  can 
probably  be  excavated  without  blasting.  With- 
in a  mile  and  a  half  of  the  lake  the  line  crosses 
the  Rio  Lajas  four  times.  This  stream  appears 
to  be  flowing  in  an  old  channel  which  was  some- 
what deeper  than  its  present  channel  and  which 
has  been  silted  up.  The  geological  significance 
of  this  old  channel  has  been  pointed  out  in  an 
earlier  part  of  this  report.  It  considerably  in- 
creases the  proportion  of  soft  material  to  be  ex- 
cavated on  this  part  of  the  canal  line.  Beyond 
this  old  channel  the  surface  is  covered  with  a 
verv  uniform  layer  of  residual  clav  derived  from 
the  decay  of  the  underlying  shales.  Its  thick- 
ness varies  from  four  to  six  feet  and  it  passes 
downward  somewhat  abruptly  into  the  underly- 
ing disintegrated  shale  or  cascajo.  As  indicated 
by  the  Canal  Company's  borings  the  disintegra- 
tion of  the  rock  has  extended  to  a  somewhat 
greater  depth  upon  the  Divide  than  elsewhere, 
and  if  the  conditions  are  found  to  be  as  repre- 
sented on  the  section,  the  hard  rock  will  extend 
but  a  few  feet  above  the  water  level  in  the  canal 
through  the  greater  portion  of  the  Divide  cut. 
The  hard  rock  is  represented  as  passing  below 


166 


NICARAGUA   CANAL  COMMISSION 


the  bottom  line  of  the  canal  between  six  and 
seven  miles  from  the  lake. 

The  Rio  Grande  is  also  found  to  be  flowing 
in  an  old  channel  which  has  been  in  part  silted 
up.  The  present  river  channel  occupies  from  a 
third  to  a  half  of  the  old  channel.  Bv  a  careful 
examination  of  the  present  river  banks  it  has 
been  possible  to  map  the  old  channel  with  tol- 
erable accuracy.  The  Canal  Company's  borings 
have  given  its  depth  and  upon  this  basis  the 
canal  profile  has  been  constructed,  showing  the 
proportions  of  earth  and  disintegrated  rock  to  be 
excavated.  On  the  Childs  route,  Variant  II,  no 
excavation  wnll  be  required  between  the  head  of 
the  Rio  Grande  flood-plain  and  the  dam  at  La 
Flor.  Three  sections  were  made  bv  the  Canal 
Company  on  the  site  of  the  proposed  locks  in  the 
hills  north  of  the  La  Flor  dam  site.  The  records 
of  these  holes  would  be  difficult  to  interpret  but 
for  the  work  done  under  tlie  direction  of  the 
Commission  at  La  Flor.  The  surface  is  covered 
with  a  thin  mantle  of  residual  clay  which  passed 
downward  into  disintegrated  rock.  Below  the 
disintegrated  layer  the  rock  consists  of  inter- 
bedded  sandstones  and  shales,  the  latter  being 
rather  soft  and  intersected  by  many  joints.  A 
considerable  proportion  of  the  material  to  be  ex- 
cavated in  these  hills  and  in  the  foundations  for 
the  locks  should  be  classed  as  hard  rock,  but  it 
is  impossible  with  the  present  information  to 
make  definite  statements  concerning  the  propor- 
tions of  hard  and  soft  rock.  Beyond  La  Flor 
the  excavation  will  be  entirely  in  alluvial  ma- 
terial consisting  of  clay  and  sand  to  the  site  of 
Brito  harbor. 

Only  a  single  route  has  been  considered  from 
the  lake  to  the  Cano  Guachipilin.  From  this 
point  westward  three  alternatives  have  been  con- 
sidered. These  are,  the  three  variants  of  the 
Childs  route  described  in  the  report  of  the  Chief 


Engineer.  Variant  III  follows  the  north  side 
of  the  Rio  Grande  valley;  and,  Variant  I  follows 
the  south  side  of  the  vallev.  The  classification 
of  materials  on  Variant  II  has  alreadv  been 
given.  Variant  III  provides  for  a  dam  across 
the  Rio  Gi-ande  at  Buen  Retiro,  the  canal  paSvS- 
ing  through  the  low  saddle  north  of  the  hill 
which  here  occupies  the  center  of  the  valley. 
Ten  holes  were  put  down  by  the  Commission  on 
this  line  with.in  a  distance  of  about  two  miles 
from  the  crest  of  the  Buen  R(»tiro  saddle. 
These  holes  show  that  the  hill  in  the  center  of 
the  vallev  was  former Iv  an  island  in  the  river. 
There  is  an  old  (»hannel  to  the  north  of  it,  ex- 
tending to  a  depth  of  seventy  feet  below  the 
present  surface,  the  material  with  which  it  is 
filled  being  compacted  sand.  Three  thousand 
feet  beyond  the  saddle  the  line  crosses  a  spur 
from  the  hills  to  the  north,  the  old  channel  bend- 
ing to  the  left  and  joining  the  present  river  chan- 
nel. Sandstone  is  found  beneath  a  thin  mantle 
of  residual  clay  on  the  point  of  this  spur.  Be- 
yond this  the  alluvium  of  the  present  Rio 
Grande  flood-plain  is  encountered,  and  this  ex- 
tends below  the  bottom  of  the  canal  entirelv  to 
Brito.  The  hills  north  of  Buen  Retiro  are 
composed  of  hard  black  crystalline  rock  which 
is  probably  a  large  intrusive  mass  in  the  Brito 
fonnation. 

Variant  I  follows  the  southern  side  of  the 
Rio  (jrande  >'alley  from  a  point  above  Buen 
Retiro  to  Brito.  It  also  involves  a  dam  at  the 
same  point  as  Variant  III.  The  excavation  on 
the  south  ^de  of  the  vallev  will  bo  chieflv  in 
residual  clay  and  disintegrated  rock  to  a  point 
nearly  oj)posite  the  mouth  of  the  Rio  Tola. 
From  this  point  to  La  Flor  the  excavation  will 
be  in  the  alluvial  silt  of  the  Rio  Grande  flood- 
plain.  At  La  Flor  the  point  of  the  hill  which 
forms  the  southern  end  of  the  proposed  La  Flor 


APPENDIX  II.— GEOLOGIC  REPORT 


167 


dam  is  utilized  as  a  site  for  a  lock.  The  rock 
here  is  entirely  a  disintegrated  sandy  shale,  and 
probably  no  solid  rock  would  be  encountered. 
The  remainder  of  the  excavation  to  Brito  will 
be  entirely  in  alluvial  silt  with  the  exception  of 
a  short  distance  through  a  hill  on  the  south  side 
of  the  valley  which  has  been  selected  as  a  lock 
site.  The  depth  of  the  residual  clay  in  this  hill 
has  been  taken  at  about  twelve  feet,  and  it  is 
assumed  that  below  this  will  be  found  disinte- 
grated rock  extending  below  the  bottom  of  the 
lock  foundation.  This  disintegrated  rock,  how- 
ever, is  abundantly  competent  to  sustain  any 
structure  such  as  a  lock  which  may  be  placed 
upon  it. 

Dam  Sites  on  the  Rio  San  Juan. — Sections 
showing  the  geological  conditions  at  the  pro- 
posed sites  of  eight  dams  across  the  San  Juan 
have  been  prepared  for  use  by  the  engineers  in 
making  estimates.  Xo  boring  w^as  done  with 
special  reference  to  three  of  these  sections  which 
are  therefore  based  upon  the  general  series  of 
river  holes.  Five  of  the  proposed  sites  were 
more  or  less  thoroughly  investigated  with  special 
reference  to  their  use  for  dams.  The  sections 
of  these  will  be  found  on  Plate  XVII. 

Castillo. — At  Castillo  the  site  selected  for  a 
dam  required  by  one  of  the  variant  plans,  is 
immediately  above  the  rapids.  But  little  bor- 
ing was  required  here  to  determine  the  character 
of  the  material  forming  the  river  bed  and  hence 
the  foundation  of  the  proposed  dam.  The  rap- 
ids are  formed  by  solid  ledges  of  basalt  included 
with  the  group  of  trap  rock  already  described. 
At  low  Stages  of  the  river  the  rock  can  be  readily 
examined  on  either  side.  It  is  intersected  by 
horizontal  joint  planes  which  give  it  somewhat 
the  appearance  of  a  stratified  rock.  It  is  be- 
lieved that  the  rock  in  the  bed  of  the  river  is 
firm  and  solid  and  will  fonn  a  suitable  founda- 


tion for  any  structure  which  it  may  be  desired 
to  place  on  it.  In  the  hills  on  either  side  of 
the  river  the  rock  is  considerably  fractured  near 
the  surface  and  the  slopes  are  covered  with 
talus,  but  the  solid  rock  is  exposed  at  various 
points  and  no  difficulty  need  be  apprehended  in 
securing  suitable  anchorages.  Three  holes  were 
put  down  here,  two  on  opposite  sides  of  the 
rapids,  and  one  below  on  the  south  side.  The 
first  two  penetrated  solid  rock  from  the  bed  of 
the  stream  downward,  while  the  one  below  the 
rapids  revealed  a  deep  hole  excavated  in  the  rock 
in  the  nature  of  a  large  pothole.  Some  addi- 
tional topography  should  be  taken  on  the  north 
side  of  the  river  before  a  suitable  site  for  locks 
can  be  selected. 

Upper  Machuca. — The  next  site  selected  as  a 
possible  dam  site  is  about  three  miles  above  Ma- 
chuca. Xo  borings  were  made  directly  upon 
this  site  so  that  the  section  rests  largely  upon 
inferences  from  the  character  of  the  river  bed 
as  revealed  by  borings  short  distances  above  and 
below.  The  rock  here  is  calcareous  sandstone, 
belonging  to  the  Machuca  formation,  which  is 
not  usually  found  weathered  to  anything  like 
the  same  depth  as  the  igneous  rocks  of  the 
region.  Solid  rock  is  usually  found  under  a 
few  feet  of  sand  in  the  river  channel,  but  the 
rock  in  the  adjacent  hills  is  probably  weathered 
down  nearly  to  the  same  level  as  the  surface  of 
the  solid  rock  in  the  channel,  so  that  the  an- 
chorages must  be  in  residual  clay  and  soft  rock. 

Machuca. — Section,  Fig.  3,  Plate  XVII. — 
The  Machuca  dam  site  is  located  about  half  a 
mile  below  the  mouth  of  the  Cano  Machuca  at 
the  upper  end  of  Campaiia  island.  Six  holes 
were  put  down  on  the  center  line;  one  on  the 
north  bank  of  the  river,  one  in  each  channel  on 
opposite  sides  of  the  island,  and  three  on  the 
south  bank.     The  Machuca  sandstone  is  exposed 


168 


NICARAGUA  CANAL  COMMISSION 


on  the  north  bank  of  the  river.  It  is  a  fine- 
grained, light  bluish-gray  rock,  evenly  bedded 
and  closely  resembling  a  fine-grained  quartzite. 
It,  however,  contains  some  carbonate  of  lime  as 
well  as  some  feldspathic  minerals  and  much  dis- 
seminated pyrite.  The  beds  have  a  dip  of  about 
12°  to  the  west,  that  is  upstream. 

The  hole  on  the  north  bank  penetrated  twelve 
feet  of  tough  red  clay  and  then  twenty-six  feet 
of  soft  vellow  and  w^hite  rock  derived  from  the 
decay  of  the  Machuca  sandstone,  and  at  a  depth 
of  thirty-eight  feet  from  the  surface  encountered 
a  hard  sandstone  similar  to  that  exposed  on  the 
river  bank.  In  the  center  of  the  north  channel 
a  few  inches  of  sand  were  found,  under  which 
is  hard  sandstone.  The  sandstone  is  also  ex- 
posed on  both  sides  of  Campafia  island  near 
its  upper  end.  It  here  has  the  same  character 
as  on  the  north  bank.  At  the  extreme  upper 
point  of  the  island  there  are  large  blocks  of  ig- 
neous rock  which  appear  to  be  nearly  if  not 
quite  in  place.  This  rock  is  a  weathered  dio- 
rite  and  probably  occurs  as  a  dike  intersecting 
the  Machuca  sandstone.  In  the  center  of  the 
south  channel  there  are  about  seven  feet  of 
boulders  and  sand,  then  twelve  feet  of  soft  rock, 
below  which  the  hard  sandstone  is  encountered 
at  a  depth  of  thirty-five  feet  below  the  water 
surface.  The  two  holes  located  on  the  south 
bank  near  the  outer  and  inner  edges  of  the  flood- 
plain,  penetrated  silt  and  sand  to  a  depth  of 
about  twenty-eight  feet  from  the  surface,  and 
then  soft  rock  for  a  distance  of  about  twenty 
feet.  The  hole  upon  the  river  bank  reaches 
hard  rock  at  a  depth  of  fifty  feet  below  the  sur- 
face. The  hole  on  the  hillside  at  the  south  end 
of  the  dam  shows  forty  feet  of  red  and  yellow 
clay  and  ninety  feet  of  clay  and  soft  rock.  The 
great  depth  to  which  the  rock  is  here  weathered 
is  somewhat  surprising  since  it  does  not  appear 


to  differ  essentially  from  that  found  on  the  north 
side  of  the  river,  where  the  depth  of  weathered 
material  is  only  moderate.  It  seems  probable 
that  the  presence  of  the  diorite  dike  in  the  sand- 
stone has  led  to  its  more  rapid  decay  here  than 
elsewhere.  Large  blocks  of  the  diorite  are 
found  at  the  head  of  the  island,  as  stated  above, 
and  residual  boulders  of  the  same  rock  are  found 
in  the  red  clav  on  the  hills  south  of  the  river. 
It  is  quite  probable  that  hard  rock  wnll  be  found 
much  nearer  the  surface  a  short  distance  either 
up  or  down  the  river.  The  influence  of  the 
dike  probably  does  not  extend  more  than  a  few 
hundred  feet  on  either  side  of  the  center  line  of 
the  dam.  Of  the  two  channels  the  one  on  the 
north  side  of  Campafia  island  now  carries  the 
most  water.  The  south  channel,  however,  was 
form(»rly  much  the  larger  and  this  channel  has 
been  contracted  to  half  its  original  dimensions 
by  the  deposition  of  silt.  At  present  the  river 
appears  to  be  cutting  only  upon  the  north  bank. 
Conchuda, — Xo  borings  were  made  with  a  di- 
rect reference  to  the  investigation  of  a  dam  site 
at  this  point.  A  few  holes  were  put  down  in 
the  vicinity,  however,  which  afford  a  fairly 
satisfactory  measure  of  the  depth  of  the  old  river 
channel  and  afford  some  information  concerning 
the  character  of  the  rock  and  the  depth  of  rock 
decay.  The  depth  of  the  old  river  channel  is 
about  sixtv-five  feet  below  the  level  of  the  flood- 
plain,  or  four  feet  above  sea  level.  This  old 
river  channel  is  partially  filled  with  fine  clay, 
silt  and  sand.  The  river  appears  to  be  cutting 
its  southern  bank  and  has  perhaps  recently  modi- 
fied the  slope  of  the  old  valley.  The  rock  in 
this  region  is  a  sandstone  containing  a  very 
large  proportion  of  volcanic  material.  In  a 
hole  on  the  point  of  the  hill  at  the  Conchuda 
cut-off  the  depth  of  the  residual  clay  was  found 
to  be  fifty-four  feet.     Below  this  soft  rock  was 


APPENDIX  II.— GEOLOGIC   REPORT 


169 


penetrated  to  some  distance,  growing  gradually 
harder  and  probably  passing  into  hard  rock  at 
a  depth  of  about  sixty-five  feet  from  the  surface. 
It  will  be  readily  understood  that  the  informa- 
tion  concerning  conditions  at  this  point  is  suffi- 
cient only  for  a  preliminary  estimate  and  that 
further  boring  would  be  necessary  before  final 
plans  could  be  made  if  it  should  be  selected  as 
a  dam  site. 

Boca  San  Carlos, — Section,  Fig.  4,  Plate 
XVII. — The  dam  site  at  the  Boca  San  Carlos 
extends  from  the  point  of  a  spur' connected  with 
the  high  hills  lying  between  the  San  Juan  and 
the  San  Carlos  and  a  long  spur  from  the  lower 
hills  to  the  north  of  the  San  Juan  valley.  Six 
holes  were  put  down  on  the  center  line  of  the 
dam  site  and  one  at  a  little  distance  from  it  to 
the  east.  Of  these  one  is  upon  the  flank  of  the 
hill  to  the  north,  three  on  the  flood-plain,  one 
in  the  river  channel  near  the  northern  bank  and 
one  on  the  hill  to  the  south  of  the  river.  The 
sections  derived  from  four  of  these  holes  are 
shown  on  Plate  XIII.  On  the  north  side  of  the 
river  above  the  margin  of  the  flood-plain  the  red 
and  yellow  clay  has  a  depth  of  about  twenty 
feet.  Below  this  is  soft  rock  containing  many 
residual  boulders  derived  from  the  decav  of  ba- 
saltic  lava.  The  depth  to  hard  rock,  which  was 
reached  only  in  one  of  three  holes,  above  the 
flood-plain,  and  tliat  at  a  distance  of  1000  feet 
east  of  the  dam  line,  is  probably  between  fifty 
and  sixty  feet  from  the  surface.  The  holes 
upon  the  flood-plain  and  at  the  edge  of  the 
river  channel  pass  through  silt  and  sand  to  a 
maximum  depth  of  fifteen  feet  below  sea  level 
or  eighty-two  feet  below  the  surface  of  the  flood- 
plain.  This  is  the  greatest  depth  of  the  old 
river  channel  at  this  point.  The  position  of  the 
present  river  is  at  the  extreme  southern  side  of 
the  old  channel,  and  it  appears  to  be  cutting 


this  bank  to  a  moderate  extent.  On  the  south 
side  of  the  river  the  red  and  yellow  clay  has  a 
depth  of  forty  feet  and  the  soft  rock  an  equal 
depth,  making  the  distance  from  the  surface  to 
hard  rock  eighty  feet.  Both  the  residual  clay 
and  the  soft  rock  contain  many  residual  boulders 
of  hard  rock,  and  the  distinction  between  the 
two  clashes  of  material  is  not  sharp.  The  ma- 
terial filling  the  old  river  channel  is  in  part 
black  sand  and  in  part  fine  blue  sandy  clay  silt. 
The  sand  is  doubtless  derived  from  the  San 
Carlos  river,  being  similar  to  that  found  in  the 
river  channel  from  the  mouth  of  the  San  Carlos 
to  the  sea.  When  the  San  Juan  is  low  and  the 
San  Carlos  is  in  flood,  the  current  in  the  former 
is  reversed,  and  the  black  sand  brought  down 
by  the  latter  has  been  carried  some  distance  up 

the  San  Juan.  The  silt  and  the  sand  are  not 
separated  by  a  distinct  plane,  but  are  to  a  certain 

extent  interstratified  at  their  contact. 

It  is  evident  that  the  foundation  for  a  masonry 
dam  will  have  to  be  carried  down  to  solid  rock, 
which  is  found  at  the  bottom  of  this  old  channel. 
At  the  ends  of  the  dam  the  foundation  should 
be  carried  down  to  hard  rock,  at  least  as  far  into 
the  hills  as  the  end  of  the  crest  over  which  the 
water  is  allowed  to  discharge.  Beyond  this  the 
soft  rock  will  probably  afford  a  sufficiently  solid 
foundation. 

Oc/roa.— Section,  Fig.  5,  Plate  XVII.— More 
systematic  work  was  done  under  the  direction  of 
the  Commission  at  Ochoa  than  elsewhere,  and 
the  information  concerning  the  underground 
conditions  is  correspondingly  complete.  The 
conditions  actually  found  and  inferred  were  rep- 
resented for  use  of  the  engineers  by  means  of 
seven  section^s — three  transverse  and  four  longi- 
tudinal. One  transverse  section  (C),  the  one  re- 
ferred to  alMJve,  Fig.  5,  Plate  XVII,  is  approxi- 
mately upon  the  center  line  of  the  proposed  dam 


170 


NICARAGUA   CANAL  COMMISSION 


as  located  by  the  Canal  Company.  This  section 
is  based  on  the  results  obtained  in  eleven  holes 
and  may  be  regarded  as  very  accurately  repre- 
senting the  conditions  as  they  actually  exist. 
Two  additional  sections  are  given  parallel  with 
the  center  line  of  the  dam  and  about  two  hun- 
dred feet  on  either  side.  The  downstream  sec- 
tion (B)  is  based  on  two  holes  on  the  south  side 
and  one  on  the  north  side  of  the  river.  So  far 
as  they  were  determined  the  conditions  here  cor- 
respond very  nearly  with  those  on  the  center 
line.  The  upstream  section  (A)  is  based  on  the 
inferred  rock  slopes  represented  on  the  longitu- 
dinal sections. 

It  should  be  noted  that  two  distinct  classifica- 
tions are  represented  on  this  section.  One  is 
purely  from  the  engineer's  standpoint  and  con- 
sists as  elsewhere  of  alluvial  silt,  residual  clay, 
soft  rock  and  hard  rock.  The  geological  classi- 
fication has  been  referred  to  on  a  previous  page 
and  is  quite  different.  Thus  the  residual  clay 
and  soft  rock  are  derived  from  three  entirely 
distinct  formations,  which  differed  somewhat 
widely  in  their  original  composition  and  appear- 
ance. The  hard  rock  on  the  south  side  of  the 
river  is  composed  of  two  distinct  varieties  of 
lava,  while  that  on  the  north  side  is  composed 
of  a  volcanic  conglomerate  or  sandstone.  The 
residual  clay  as  elsewhere  is  deep  red  in  color 
for  a  distance  of  ten  or  twelve  feet  from  the 
surface,  below  which  it  is  generally  blue  or  gray, 
and  becomes  less  plastic  downward.  It  merges 
into  soft  rock  by  insensible  gradations,  so  that 
the  line  separating  the  two  classes  of  material 
is  here  as  elsewhere  to  a  large  extent  arbitrary. 
As  stated  above,  the  soft  rock  is  derived  from 
three  distinct  formations,  and  its  character  varies 
somewhat  with  the  original  character  of  the 
rock.  The  most  compact  is  that  derived  from 
the    volcanic    sandstone.      Next,    that    derived 


from  the  dacite,  although  the  latter  is  apt  to  be 
talcose  and  hence  would  not  form  a  reliable 
foundation  material.  The  soft  rock  derived 
from  the  basalt  varies  in  character  with  the 
original  character  of  that  rock.  Where  the  lat- 
ter was  compact  the  material  resulting  from  its 
weathering  is  also  compact,  and  where  it  was 
vesicular  the  resulting  material  is  porous. 

Lower  Ochoa, — Section,  Fig.  G,  Plate  XVII. 
— Six  holes  were  ])ut  down  at  the  proposed  dam 
site  at  lower  Ochoa,  two  on  either  bank  and  two 
in  the  river  channel.  These  holes  reveal  con- 
ditions which  are  very  much  less  favorable  for 
foundations  than  was  anticipated.  The  rock 
forming  the  surface  is  a  volcanic  conglomerate 
or  breccia  somew^iat  similar  to  that  underlying 
the  basalt  at  upper  Ochoa.  On  the  south  side 
of  the  river  this  is  weathered  only  to  a  moderate 
depth  of  about  forty-five  feet,  while  on  the  north 
side  it  is  weathered  to  a  much  greater  depth,  in 
fact,  entirely  to  the  bottom  of  this  formation. 
On  the  south  side  it  has  a  depth  of  about  fifty 
feet,  and  is  underlain  bv  a  bed  of  hard  basalt. 
The  upper  surface  of  the  basalt,  which  is  doubt- 
less a  lava  flow,  dips  rapidly  to  the  north  and 
passes  from  about  thirty-five  feet  above  sea  level 
on  the  south  side  to  eighty-five  below  sea  level 
on  the  north  side  of  the  river.  As  stated  above, 
the  volcanic  conglomerate  and  basalt  are  in  con- 
tact on  the  south  side  of  the  river,  but  on  the 
north  they  are  separated  by  the  thin  edges  of 
two  other  formations.  These  are  a  bed  of  soft 
talcose  volcanic  rock,  probably  tuff,  about 
twenty  feet  thick  and  a  bed  of  extremely  soft 
sandstone  or  partially  cemented  sand  which  con- 
tains nunioriiis  fragments  of  wood,  leaves,  etc. 
This  latter  material  is  undoubtedly  of  sedimen- 
tary origin,  but  the  constituents  are  probably 
derived  in  large  part  from  a  volcanic  source. 

It  is  thus  seen  that  in  order  to  secure  a  solid 


APPENDIX  II.— GEOLOGIC   REPORT 


171 


foundation  on  the  north  side  of  the  river  it  would 
be  necessary  to  go  down  to  the  surface  of  the 
basalt,  which  is  eighty-five  or  more  feet  below 
sea  level  and  at  least  135  feet  below  the  surface 
of  the  river. 

Tamhor  Grande, — Section,  Fig.  7,  Plate 
XVII. — Five  holes  were  put  down  at  tlie  Tarn- 
bor  Grande  dam  site,  two  on  either  bank  and  one  , 
in  the  river  channel.  The  geological  condi- 
tions found  at  this  site  are  more  uniform  than 
those  observed  at  any  other  point.  Only  a 
single  gf^ological  fonnation  was  encountered, 
namely,  dacije.  This  is  a  rather  coarse  granu- 
lar gray  crj'^stalline  rock  which  weathers  uni- 
formlv  from  the  surface  downward,  the  weath- 
ered  products  containing  no  residual  boulders  of 
fresh  rock.  The  surface,  as  elsewhere,  is  cov- 
ered with  red  clay  which  passes  down  into  the 
soft  rock  by  a  gradual  transition.  The  soft 
rock  in  turn  becomes  gradually  harder  down- 
ward, and  at  a  depth  varying  between  100  and 
120  feet  from  the  surface  the  rock  becomes  suf- 
ficiently hard  to  yield  a  continuous  core  with  the 
diamond  drill.  The  surface  of  the  hard  rock 
has  a  somewhat  more  gentle  slope  than  the  pres- 
ent land  surface.  The  hole  in  the  river  channel 
and  the  one  on  the  flood-plain  north  of  the  river 
revealed  the  presence  of  an  old  river  channel  of 
great  depth.  The  hole  on  the  flood-plain  passed 
through  thirty  feet  of  fine  silt,  then  alternate 
beds  of  silt  and  sand,  and,  at  a  depth  of  eighteen 
feet  below  sea  level,  j)enetrated  the  soft  weath- 
ered dacite,  and,  at  forty  feet  below  sea  level, 
hard  rock.  The  hole  in  the  river  penetrated 
black  sand  to  a  depth  of  108  feet  below  sea  level 
when  the  hard  dacite  was  encountered.  The 
black  sand  throughout  the  entire  distance  was 
very  uniform  in  character,  except  that  a  few 
boulders  were  found  immediately  overlying  the 
hard  rock  in  the  bottom  of  the  channel.     Draw- 


ing a  line  through  the  points  which  mark  the 
bottom  of  the  alluvial  material  and  continuing 
the  slope  of  the  southern  bank  downward  until 
it  meets  the  other  line,  a  symmetrical  curve  is 
obtained  which  probably  very  nearly  represents 
the  outline  of  the  old  river  channel.  The  find- 
ing of  a  sand-filled  channel  at  the  Tambor 
Grande  site  was  by  no  means  a  surprise,  though 
it  was  scarcely  expected  to  find  it  so  deep.  From 
the  borings  which  had  been  made  at  various 
points  on  the  river  above,  it  was  found  that  the 
old  river  channel  had  a  fairly  uniform  gradient 
which  was  considerably  steeper  than  the  gradient 
of  the  present  river.  Thus  from  Castillo  to 
Ochoa  the  gradient  averages  three  feet  to  the 
mile,  while  from  Ochoa  to  Tambor  Grande  it 
averages  5.8  feet  to  the  mile.  The  observed 
irregularities  in  the  gradient  are  doubtless  con- 
nected with  variations  in  the  hardness  of  the  un- 
derlying rock. 

EMBANKMKirr  Lines. — San  Carlos, — Two  em- 
bankment lines  have  been  examined  connecting 
the  hills  southeast  of  the  Boca  San  Carlos  with 
the  upper  and  lower  dam  sites.  The  section  of 
the  embankment  line  which  reaches  the  river  at 
upper  Ochoa  is  based  upon  surface  examination 
and  borings  made  by  the  Canal  Company.  The 
conditions  are  verv  similar  to  those  found  at  the 
south  end  of  the  Ochoa  dam  site.  The  rocks  of 
the  region  are  basalts  forming  a  heavy  mantle  of 
deep  red  clay  at  the  surface  with  soft  rock  be- 
low, both  the  clay  and  soft  rock  containing 
numerous  residual  boulders.  The  depth  from 
the  surface  down  to  hard  rock  is  probably  from 
sixty  to  one  hundred  feet.  The  line  reaching 
the  river  at  lower  Ochoa  is  based  upon  surface 
examination  and  seven  holes  put  down  under  the 
direction  of  the  Commission.  From  the  river 
to  a  point  where  the  line  approaches  nearest 
Cano  Curano  the  surface  rock  is  the  volcanic 


172 


NICARAGUA   CANAL  COMMISSION 


conglomerate  shown  in  the  section  at  lower 
Ochoa.  This  is  weathered  to  a  great  depth, 
forming  a  brown  sandy  clay;  The  holes  were 
put  down  below  sea  level,  varying  in  depth  from 
80  to  130  feet,  but  did  not  reach  hard  rock  ex- 
cept in  the  hole  farthest  from  the  river  where 
the  rock  is  basalt  similar  to  that  on  the  upper 
line.  It  was  assumed  in  investigating  these  em- 
bankment lines  that  the  waste-wxirs  and  sluices 
would  be  of  such  a  character  that  firm  clay 
would  afford  a  suitable  foundation.  If  a  rock 
foundation  is  essential  it  will  be  found  at  a 
much  shorter  distance  below  the  surface  on  the 
upper  than  on  the  lower  line.  It  is  thus  seen 
that  the  upper  and  lower  embankment  lines  have 
about  the  same  relative  advantages  as  do  the 
corresponding  dam  sites. 

San  Francisco, — See  sections.  Figs.  1  to  4, 
Plate  XVIII. — On  the  San  Francisco  embank- 
ment line  borings  were  made  by  the  Commis- 
sion only  on  the  flood-plains  of  the  streams  to 
determine  the  depth  of  their  alluvial  deposits. 
Three  holes  were  put  down  in  the  Florida  la- 
goon, three  in  the  flood-plain  of  the  San  Fran- 
cisco, and  one  each  at  the  Nicholson  and  Chan- 
chos.  A  study  of  the  physiography  of  the  re- 
gion had  already  indicated  the  existence  of  an 
old  land  surface  developed  in  the  region  when  it 
stood  at  a  higher  altitude  than  now  and  subse- 
quently in  part  concealed  by  the  alluvial  deposits 
of  the  present  streams.  These  borings  deter- 
mined the  character  of  the  alluvial  materials 
and  the  depth  of  the  former  valleys.  It  was 
found  that  the  slopes  of  the  present  valleys  if 
continued  below  the  covering  of  alluvium  would 
coincide  with  the  surface  of  the  old  vallev.  The 
depth  of  the  alluvial  filling  having  been  deter- 
mined at  a  few  points,  it  was  possible  to  draw 
contours  representing  the  surface  of  the  old  val- 
leys, and  thus  to  show  the  probable  depth  of  the 


alluvium  at  any  point.     There  are  two  swamps 

crossed  bv  the  embankment  line  between  the 
Florida  lagoon  and  the  Chanchos  which  have  not 

been  investigated  with  the  drill.     Since  these 

swamps  occupy  valleys  trilnitary  to  the  Danta 

and  the  Nicholson  thev  could  not  have  been 

»• 

deeper  than  the  tnmk  valley  at  the  point  where 
they  joined  the  latter.  The  depth  of  the  allu- 
vium in  the  trunk  valley  having  been  deter- 
mined, it  is  therefore  certain  that  the  depth  in 
the  tributary  will  be  at  least  no  greater.  Hence 
while  the  section  through  these  swamps  is  based 
upon  an  inference,  it  is  of  such  a  character  that 
it  is  considered  nearly  as  satisfactory  for  giving 
a  maximum  measure  of  the  silt  as  an  actual  ex- 
amination with  the  drill.  In  all  of  these  old 
valleys  residual  clay  and  soft  rock  are  found  be- 
neath the  alluvium,  although  they  are  not  so 
thick  as  upon  the  adjacent  hills.  The  rock  ob- 
tained beneath  the  alluvium  and  residual  mate- 
rial is  only  moderately  hard,  consisting  chiefly  of 
talcose  volcanic  tuff  with  the  thin  bed  of  earthy 
limestone  already  described  at  the  San  Fran- 
cisco. The  remainder  of  the  section  showing 
the  geological  conditions  and  classification  of 
material  in  other  portions  of  the  San  Francisco 
embankment  line  than  those  noted  above,  is 
based  upon  a  few  borings  made  by  the  Canal 
Company  or  on  inferences  from  borings  made 
bv  the  Commission  at  various  dam  sites  in  the 
vicinity. 

Tamhorcito  Point. — One  of  the  alternative 
lines  at  Tamborcito  swings  to  the  south  around 
the  point  of  the  hills  and  avoids  the  deep  cut 
involved  in  the  other  line.  It  encroaches,  how- 
ever, upon  the  channel  of  the  river  and  requires 
an  embankment  from  the  point  of  thq  hills  to 
the  lower  end  of  Tamborcito  island  and  thence 
across  the  northern  channel  to  the  north  bank. 
No  reliable  information  is  available  concerning 


APPENDIX  II.— GEOLOGIC  REPORT 


173 


the  character  of  the  foundation  for  this  embank- 
ment. A  line,  however,  has  been  drawn  on  the 
section  to  indicate  the  probable  limit  of  the  allu- 
vial material.  This  line  is  based  on  the  known 
depth  of  the  old  river  channel  at  Tambor  Grande 
and  on  the  slopes  of  the  adjacent  hills.  The  ma- 
terial below  is  probably  hard  rock  similar  to  that 
exposed  at  water  level  and  in  the  point  of  the 
hills.  That  above  the  line  is  chiefly  black  sand 
with  sandy  silt  forming  the  island  and  the  flood- 
plains  north  of  the  river.  It  should  be  clearly 
understood  that  this  line  represents  only  a  fair 
degree  of  probability.  There  can  be  little 
doubt,  however,  that  the  black  sand  has  a  depth 
of  at  least  eighty  feet  on  the  line  of  the  embank- 
ment, and  it  may  be  considerably  greater.  Hence 
it  will  probably  be  necessary  to  design  an  em- 
bankment which  can  rest  upon  this  sand  as  a 
foundation. 

Tamhorcito  Lagoon, — Section,  Fig.  5,  Plate 
XVIII. — An  essential  part  of  the  plan  which 
involves  the  construction  of  a  dam  at  Tambor 
Grande,  is  an  embankment  connecting  the  hills 
immediately  south  of  the  river  with  the  high 
land  in  the  interior.  This  necessitates  the  filling 
of  a  few  gaps  in  the  crest  of  the  hills  between 
the  river  and  Tamborcito  creek.  This  latter 
stream  meanders  through  a  broad  alluvial  flat, 
similar  to  those  which  border  the  San  Francisco 
and  Danta  creeks.  This  alluvial  flat  is  a  lagoon 
more  or  less  perfectly  silted  up  and  forested. 
Four  holes  were  put  down  to  determine  the 
depth  of  the  alluvial  material.  The  old  resid- 
ual surface  beneath  the  alluvium  is  found  to 
be  somewhat  irregular,  as  might  have  been  ex- 
pected from  a  consideration  of  the  geological 
historj^  of  the  region.  The  greatest  depth  of  the 
alluvium  was  found  to  be  eighty-six  feet,  or 
forty-six  feet  below  sea  level.  Since  the  foun- 
dations for  an  embankment  of  the  height  re- 


quired would  have  to  rest  upon  material  at  least 
as  firm  as  residual  clay,  the  difficulties  of  con- 
structing such  an  embankment  across  the  Tam- 
borcito valley  would  be  very  considerably  great- 
er than  across  the  San  Francisco  valley.  This 
embankment  line,  therefore,  has  about  the  same 
degree  of  availability  compared  with  the  San 
Francisco  embankment  line  as  the  Tambor 
Grande  dam  site  has  compared  with  the  Ochoa 
dam  site. 

Excavation  Lines,  Eastern  Division. — River 
Sectioriy  Lull  Route. — The  information  con- 
cerning the  materials  fonning  the  bed  of  the 
San  Juan  is  based  chiefly  upon  a  series  of  bor- 
ings made  under  the  direction  of  the  Commis- 
sion, extending  from  a  point  in  Lake  Nicaragua 
one  and  a  quarter  miles  from  its  outlet  down  the 
river  to  the  Colorado  junction.  From  the  lake 
to  the  Toro  rapids  the  holes  were  put  down  at 
intervals  of  1000  feet  with  intermediate  holes 
wherever  rock  was  encountered  or  its  presence 
above  the  datum  suspected.  Between  the  head 
of  the  Toro  rapids  and  Castillo  the  holes  were 
put  down  at  irregular  intervals  at  points  deter- 
mined by  the  configuration  of  the  banks  and  the 
presence  of  rock  outcrops.  Five  holes  were 
put  down  at  intervals  of  1500  feet  on  the  cut-off 
between  Sombrero  de  Cuero  and  Santa  Cruz. 
From  Santa  Cruz  to  Machuca  the  holes  were  at 
intervals  of  about  half  a  mile.  So  far  but  a 
single  line  of  holes  was  put  down  as  nearly  as 
possible  to  the  probable  center  line  of  the  canal. 
Below  Machuca  another  plan  was  adopted.  Cer- 
tain points  on  the  river  were  selected  at  inter- 
vals of  two  or  three  miles  and  at  each  a  trans- 
verse section  of  the  river  channel  was  developed. 
The  principal  object  here  was  to  determine  the 
depth  and  form  of  the  old  river  channel  which 
extends  from  Machuca  to  the  sea.  Additional 
holes  were  also  put  down  between  the  sections 


174 


NICARAGUA  CANAL  COMMISSION 


to  determine  the  depth  of  the  old  channel  and 
the  character  of  the  rock  in  the  river  bed. 

The  results  of  this  work  are  shown  on  the 
profiles  of  the  river  section  and  may  be  briefly 
summarized.  Between  the  lake  and  the  Toro 
rapids  the  only  points  at  which  rock  was  found 
in  the  river  channel  were  in  the  immediate  vi- 
cinity of  the  hills  which  rise  abruptly  above  the 
broad  alluvial  plain.  The  conclusion  reached 
independently  from  a  study  of  the  surface  feat- 
ures of  the  region  were  thus  verified  by  the  drill- 
ing operations,  viz.:  that  the  region  once  had 
considerably  greater  relief,  but  has  recently  been 
submerged  by  the  waters  of  the  lake,  and  the 
lower  portions  of  the  land  surface  concealed  by 
the  alluvium  which  has  filled  their  irregularities. 
While  the  work  is  not  sufficiently  extended  to 
develop  this  old  topography  to  any  considerable 
extent,  it  has  shown  that  the  slopes  of  the  old 
land  surface  beneath  the  cover  of  alluvium  are 
essentially  continuous  with  the  slopes  of  the  hills 
which  rise  above  the  low-level  plain.  This  con- 
clusion has  very  greatly  supplemented  the  in- 
formation obtained  by  drilling  and  has  afforded 
a  basis  for  the  construction  of  numerous  sections, 
both  longitudinal  and  transverse  to  the  river 
channel  at  all  points  where  rock  was  found. 
These  sections  have  been  used  to  determine  the 
distance  that  the  canal  line  should  be  shifted 
away  from  the  hills  in  order  to  reduce  the 
amount  of  rock  excavation  to  a  minimum  or 
avoid  it  entirely.  Since  it  is  probable  that  the 
canal  line  can  be  so  located  between  the  lake  and 
the  Toro  rapids  as  to  avoid  all  rock  excavation, 
the  character  of  the  rock  found  at  various  points 
in  the  channel  of  the  river  is  not  of  great  im- 
portance. It  may  be  stated,  however,  that  these 
rocks  all  belong  to  the  class  of  traps  already  des- 
cribed. AVhile  a  consideration  of  the  physio- 
graphy of  the  region  as  well  as  the  results  of 


the  boring  in  the  Toro  rapids  indicates  the  pres- 
ence of  an  old  channel  below  the  bottom  of  the 
canal,  but  subsequently  filled  with  alluvial  ma- 
terial, it  is  probable  that  this  channel  cannot  be 
followed  by  the  canal  and  consequently  some 
rock  excavation  will  be  required.  The  princi- 
pal part  of  this  will  probably  be  on  the  point 
opposite  the  mouth  of  the  Rio  Sabalos.  The 
rock  here  is  a  rather  soft  red  rock,  probably  an 
altered  vesicular  lava,  although  it  may  possibly 
be  a  consolidated  tuff.  No  samples  sufl[iciently 
fresh  for  exact  determination  were  obtained. 
But  little  excavation  will  be  required  below  the 
Toro  rapids,  except  on  the  cut-off  between  Som- 
brero de  Cuero  and  Santa  Cruz.  Five  holes 
were  put  down  approximately  on  the  canal  line 
between  these  points.  No  rock  was  encoun- 
tered, the  material  being  in  part  alluvial  and  in 
part  residual.  The  alluvial  material  was  chiefly 
verj'  fine  blue  clay,  some  portions  of  which  con- 
tained a  large  proportion  of  vegetable  matter. 
The  residual  clay  was  red  and  mottled  and  in 
places  somewhat  sandy,  containing  some  of  the 
original  minerals  but  partially  decomposed.  A 
little  hard  rock  will  be  found  above  the  datum 
75  between  Santa  Cruz  and  Castillo.  This  be- 
longs to  the  class  of  trap  already  described.  Be- 
low Castillo  the  river  bed  is  nearly  everywhere 
below  the  datum  75  and  no  excavation  will  be 
required,  except  a  small  amount  of  sand,  until 
the  Balas  rapids  are  reached,  where  the  rock 
rises  about  eight  feet  above  the  datum  for  a 
short  distance.  The  rock  here  is  the  Machuca 
sandstone  which  will  probably  be  found  more  or 
less  disintegrated  to  a  depth  somewhat  greater 
than  the  excavation.  Throughout  the  whole  ex- 
tent of  the  Machuca  rapids  rock  occurs  in  the 
bed  of  the  river.  It  is  seldom  covered  by  more 
than  a  few  feet  of  sand  and  boulders.  Hence, 
if  a  lock  is  located  at  the  upper  Machuca  dam 


APPENDIX  II.— GEOLOGIC  REPORT 


175 


site  considerable  rock  excavation  will  be  required 
between  that  point  and  Machiica.  This  excava- 
tion will  be  in  the  Machuca  sandstone,  and,  as 
shown  in  the  section  of  the  dam  site  at  Machuca, 
the  extent  to  which  it  is  weathered  is  somewhat 
variable.  The  depth  of  residual  clay  repre- 
sented on  the  section  is  more  probably  a  mini- 
mum than  an  average  measure,  and  the  amount 
of  excavation  in  hard  rock  may  be  considerably 
less  than  the  estimates  which  have  been  made. 
The  character  of  the  rock  at  the  Machuca  dam 
site  has  alreadv  been  described.  Bevond  this 
point,  through  the  Aguas  Muertas,  no  excava- 
tion will  be  required,  except  in  cut-offs,  even  if 
a  drop  is  made  both  at  the  upper  and  lower 
Machuca  dam  sites.  In  the  cut-off  at  Conchuda 
the  greater  part  of  the  excavation  will  be  in 
residual  clay  and  soft  rock.  A  core  of  hard 
rock  in  the  highest  ridge  crossed  probably  ex- 
tends to  an  elevation  of  seventy  feet  above 
tide,  or  twenty-five  feet  above  the  bottom  of  the 
canal  on  the  plan  which  provides  for  two  locks 
above  this  point.  If  the  summit  level  is  con- 
tinued eastward  to  the  Boca  San  Carlos  it  is 
probable  that  no  hard  rock  will  be  encountered 
in  the  Conchuda  cut-off. 

Menocal  Route, — The  section  of  the  high- 
level  canal  line  from  Ochoa  to  Greytown  is  based 
entirely  upon  borings  made  by  the  Canal  Com- 
pany, with  the  exception  of  four  on  the  Eastern 
Divide.  These  were  put  down  to  an  elevation 
of  sixty  feet  above  sea  level,  or  fifteen  feet  below 
the  proposed  excavation  line.  From  the  infor- 
mation afforded  by  these  four  sections  in  the 
Eastern  Divide  a  part  of  the  data  obtained  by 
the  Canal  Company  has  been  rendered  intel- 
ligible. Fourteen  holes  were  put  down  in  the 
divide  by  the  Canal  Company,  most  of  them  ex- 
tending to  an  elevation  of  seventy-five  feet  above 
sea  level,  but  the  terms  employed  in  describing 


the  material  encountered  are  so  vague  and  often 
meaningless  that  they  have  very  little  value  in 
classifying  material. 

The  comparatively  simple  geological  condi- 
tions which  prevail  in  the  Eastern  Divide  are 
shown  on  the  section.  Fig.  6,'  Plate  XVIII. 
The  rocks  forming  these  hills  are  entirely  ig- 
neous in  origin.  They  include  three  distinct 
varieties.  Since  they  all  weather  at  the  surface 
to  a  red  clay,  the  discrimination  of  these  varie- 
ties and  the  determination  of  their  underground 
relations  would  be  impossible  except  for  the  in- 
formation afforded  bv  the  drill.  The  rock  form- 
ing  the  surface  on  the  western  side  of  the  divide 
consists  of  basaltic  or  andesitic  tuff.  On  the 
Canal  Company's  sections  this  is  called  "  telpe- 
tate,^'  "  concrete,"  "  conglomerate  "  and  "  slate." 
It  is  a  dark  greenish  brown  in  color,  generally 
fine-grained,  but  occasionally  showing  frag- 
ments of  basalt  or  andesite  and  is  generally  soft 
and  talcoee.  On  exposure  to  the  air  it  loses 
water,  and  crumbles.  The  surface  of  this  basalt- 
ic tuff  dips  eastward  at  an  angle  of  five  degrees. 
It  is  overlain  by  a  lava  flow  of  dacite  about  240 
feet  in  thickness,  which  also  dips  eastward  at  a 
low  angle.  The  dacite  also  has  a  variety  of 
designations  on  the  Canal  Company's  sections. 
It  is  called  "concrete,"  "  conglomerate,"  "trap," 
"  talc  "  and  "  dacite."  It  is  deeply  weathered, 
but  becomes  gradually  harder  downward  and  at 
depths  of  50  to  175  feet  below  the  surface  it  is 
a  comparatively  fresh,  hard  rock.  Although  the 
dacite  does  not  crumble  when  exposed  to  the 
action  of  the  atmosphere,  as  the  tuff,  it  weathers 
quite  rapidly.  Cores  which  were  taken  out  by 
the  Canal  Company  and  left  on  the  surface 
showed,  after  an  exposure  of  seven  years,  a  zone 
of  weathering  which  had  penetrated  to  a  depth 
of  one-tenth  of  an  inch.  This  rate  of  alteration 
is  very  much  more  rapid  than  would  be  permis- 


176 


NICARAGUA  CANAL  COMMISSION 


sible  in  any  building  stone.  The  surface  of  the 
daeite  dips  eastward  at  an  angle  of  about  5  de- 
grees, and  it  is  overlain  by  basaltic  and  andesitic 
lavas  which  extend  eastward  to  the  margin  of 
the  San  Juan  delta.  These  lavas  in  the  Canal 
Company's  sections  are  termed  "  telpetate,^^ 
"trap,"  "talc,"  "concrete"  and  "andesite." 
They  weather  in  an  irregular  manner,  unlike  the 
daeite.  Many  residual  boulders  of  fresh  rock 
occur  in  the  red  clay  at  the  surface,  but  the 
depth  to  continuous  hard  rock  is  perhaps  greater 
than  in  areas  underlain  by  the  daeite. 

As  shown  on  the  section  of  the  Eastern  Di- 
vide tlie  sides  of  the  western  third  of  the  cut 
would  be  wholly  or  in  part  composed  of  the  ba- 
saltic tuff.  This  material,  as  explained  above 
(p.  126),  when  exposed  to  the  air  crumbles  rap- 
idly, and  it  would  therefore  constitute  a  source 
of  considerable  danger  to  the  permanence  of  the 
walls.  It  might  be  sufficiently  firm  when  first 
exposed  to  sustain  the  pressure  to  which  it  would 
be  subjected  but  would  probably  disintegrate  so 
rapidly  on  exposure  as  to  undermine  the  daeite 
and  produce  slides. 

An  attempt  has  been  made  to  estimate  the 
proportion  of  material  which  would  be  excavated 
from  the  Eastern  Divide  cut  suitable  for  dams  or 
other  structures.  It  appears  probable  that  the 
material  which  would  be  taken  out  in  blocks  of 
sufficient  size  and  which  would  resist  disintegra- 
tion, is  confined  wholly  to  the  bed  of  daeite. 
The  tuff  underlying  the  daeite  can  be  removed 
from  consideration  at  the  outset.  Even  if  it  could 
be  taken  out  in  blocks  of  sufficient  size,  which  is 
extremely  doubtful,  it  would  rapidly  disinte- 
grate when  exposed  to  the  action  of  the  atmos- 
phere, and  it  would  thus  introduce  an  element 
of  weakness  into  any  structure  to  which  it  was 
applied.  Practically  the  same  may  be  said  of 
the  basaltic  and  andesitic  lavas  overlying  the 


daeite.  While  some  durable  material  might  be 
derived  from  the  residual  boulders  in  the  clay 
and  soft  rock,  it  is  not  probable  that  any  consid- 
erable body  of  solid  rock  would  be  found  on  the 
line  of  excavation  above  the  elevation  of  75  A. 
T.  In  the  daeite  itself  the  material  classed  as 
soft  rock  would  of  course  be  excluded,  but  in 
addition  to  this  a  large  amount  of  material 
classed  as  hard  rock  from  the  standpoint  of  ex- 
cavation and  of  permanent  slopes,  would  also  be 
excluded  from  the  material  suitable  for  construc- 
tion purposes.  This  material  is  what  is  known 
to  quarrymen  as  "  dead  rock."  It  gives  a  dull 
sound  under  the  hammer,  and  when  examined 
with  the  microscope  its  minerals  are  found  to 
have  undergone  extensive  alteration.  It  is  usu- 
ally intersected  by  incipient  fractures  which 
quickly  develop  when  it  is  exposed  to  the  atmos- 
phere and  relieved  from  pressure.  It  would  be 
necessary  to  rigidly  exclude  all  such  material 
from  all  important  structures.  When  these  va- 
rious classes  of  objectionable  material  are  ex- 
cluded there  remains  about  46  per  cent,  of  the 
material  classed  as  hard  rock  or  24  per  cent,  of 
the  total  material  to  be  moved,  which  would  be 
suitable  for  use  in  large  and  permanent  struc- 
tures. 

The  borings  made  by  tlie  Canal  Company  on 
the  Menocal  route  at  other  points  than  the 
Eastern  Divide  do  not  in  any  case  penetrate  the 
hard  rock.  They  therefore  afford  merely  a 
minimum  measure  of  the  residual  mantle  of  clay 
and  soft  rock  which  covers  the  surface  of  the 
countiy.  It  is  probable,  however,  that  little,  if 
anv,  hard  rock  would  be  encountered  on  the  line 
of  the  canal,  except  at  the  Eastern  Divide.  The 
surface  of  the  hard  rock  may  extend  above  the 
bottom  line  of  the  canal  in  the  divide  between 
the  Machado  and  the  Danta  and  also  between 
the  San  Francisco  and  the  Xicholson.   There  are 


APPENDIX  II.— GEOLOGIC  REPORT 


177 


no  exact  data,  however,  for  these  portions  of  the 
line,  and  the  classification  of  materials  repre- 
sented upon  the  sections  is  derived  chiefly  by  in- 
ference from  other  localities  where  the  original 
composition  of  the  rocks  and  the  conditions  of 
rock  weathering  appear  to  have  been  similar. 
The  uncertainty  connected  with  estimates  based 
upon  such  inferences  should,  however,  be  fully 
recognized. 

Variants  of  the  Lull  Route, — The  several  va- 
riants of  the  Lull  route  are  so  nearly  on  the  same 
line  that  they  may  be  considered  together  from 
the  point  at  which  the  line  leaves  the  channel 
of  the  San  Juan  at  Boca  San  Carlos  to  the  head 
of  the  delta.  Beyond  this  point  the  three  main 
variants  diverge  so  widely  that  they  require  sepa- 
rate consideration. 

After  leaving  the  narrow  alluvial  flat  border- 
ing the  river  above  the  Boca  San  Carlos  dam  site 
the  line  crosses  a  spur  from  the  high  hills  to  the 
northward,  the  highest  point  passed  as  indicated 
by  the  profile  being  160  feet  above  sea  level. 
No  borings  have  been  made  directly  on  this  line, 
but  one  made  at  the  point  of  the  ridge  near  the 
river  and  the  series  made  on  the  line  of  the 
Boca  San  Carlos  dam  site  indicate  the  depth  of 
the  residual  clay  and  soft  rock  at  this  point. 
Following  the  rule  elsewhere  observed,  the  thick- 
nesses of  the  two  zones  are  represented  as  in- 
creasing slightly  on  the  higher  parts  of  the  ridge. 
The  section,  however,  must  be  regarded  as 
merely  tentative  and  subject  to  very  material 
modification  on  more  thorough  examination. 
It  represents  merely  a  tolerable  degree  of  prob- 
ability. After  passing  this  first  ridge  the  exca- 
vation will  be  in  silt  and  residual  clay  until  the 
point  of  the  hill  is  reached  at  the  mouth  of  the 
San  Carlos.  Here  it  is  probable  that  some  soft 
rock  will  be  encountered,  but  no  hard  rock. 

Crossing  a  broad,  alluvial  plain  formed  in  a 
12 


tributary  valley  where  only  silt  will  be  encoun- 
tered, the  line  cuts  the  points  of  the  ridge  west 
of  the  Machado.  While  no  borings  have  been 
made  in  this  ridge,  the  rocks  are  very  similar  to 
those  encountered  at  the  Ochoa  dam  site,  and  it 
is  assumed  that  the  residual  material  and  the 

* 

soft  rock  have  an  equal  depth.  If  this  is  the 
case  no  hard  rock  will  be  encountered  in  cutting 
these  points.  It  is  certain,  however,  that  nu- 
merous boulders  will  be  encountered  in  the  resi- 
dual clav,  and  these  will  become  more  abundant 
in  the  soft  rock,  possibly  forming  more  or  less 
continuous  layers.  Excavation  across  the  Ma- 
chado  valley  will  of  course  be  entirely  in  silt. 
The  high  point  just  east  of  the  Machado  forms 
the  northern  terminus  of  the  proposed  Ochoa 
dam,  and  the  materials  of  which  it  is  composed 
have  therefore  been  thoroughly  investigated. 
Above  an  elevation  of  forty-five  feet  above  tide 
the  rock  was  originally  basalt  and  below  this  con- 
sisted of  volcanic  conglomerate.  The  latter 
weathers  more  rapidly  than  the  former  so  that 
while  a  few  feet  at  the  base  of  the  basalt  are 
fresh  and  hard,  this  is  underlain  by  twenty-five 
feet  of  soft  rock,  and  the  hard  basalt  may  be  re- 
garded simply  as  a  large  boulder.  Beyond 
Ochoa  the  excavation  will  be  across  alternating 
low,  alluvial  flats  and  the  points  of  steep  ridges 
which  extend  down  to  the  river.  The  former 
contain  only  silt  and  the  latter  chiefly  residual 
clay  with  probably  a  few  points  of  soft  rock  ris- 
ing above  the  bottom  of  the  canal.  Leaving  the 
main  valley  and  following  up  the  valley  of  Em- 
bankment creek  only  residual  clay  and  a  small 
amount  of  silt  will  be  encountered,  until  the  di- 
vide is  reached  between  Embankment  creek  and 
the  drainage  of  the  Danta.  Borings  at  frequent 
intervals  have  been  made  through  this  divide  by 
the  Canal  Company.  While  none  of  them  pene- 
trate the  rock  they  afford  a  minimum  measure 


178 


NICARAGUA  CANAL  COMMISSION 


of  the  depth  of  the  residual  material,  but  prob- 
ably in  most  cases  do  not  pass  entirely  through 
it.  The  basalt  which  forms  the  surface  rock  at 
Ochoa  disappears  at  some  point  to  the  west  of 
this  divide,  and  the  underlying  volcanic  con- 
glomerate comes  to  the  surface.  As  shown  by 
the  borings  at  Ochoa,  this  conglomerate  weath- 
ers more  rapidly  than  the  basalt,  and  the  depth 
of  the  residual  material,  as  shown  by  the  Canal 
Company's  borings  and  by  those  made  at  lower 
Ochoa  through  similar  material,  is  considerably 
greater  than  where  basalt  forms  the  surface 
rock.  It  is  probable,  therefore,  that  only  resi- 
dual clay  and  soft  rock  will  be  encountered  in 
this  divide  until  the  point  selected  for  the  lock 
is  reached,  while  the  lock  foundations  will  prob- 
ably be,  in  part  at  least,  upon  hard  rock. 
Beyond  the  lopk  the  line  follows  a  tributary  of 
the  Danta,  and  finally  the  Danta  itself,  and  the 
excavation  will  be  entirely  in  clay  silt  and  resid- 
ual clay.  The  alluvium  encountered  in  the 
upper  portion  of  the  Danta  valley  will  be  found 
much  softer  than  that  forming  the  flood-plain  of 
the  river.  Lowei>  slopes  will  have  to  be  pro- 
vided for,  and  probably  in  some  cases,  as  in  the 
Florida  lagoon,  special  precautions  will  be  neces- 
sary to  prevent  the  material  from  flowing  back 
into  the  excavated  channel.  The  hills  crossed 
between  the  Danta  and  San  Francisco  rivers  are 
simply  the  protruding  points  of  much  higher 
hills  which  have  been  nearly  submerged  by  the 
alluvium.  They  are  composed  at  the  surface  of 
residual  clay  which  probably  extends  below  the 
level  of  the  surrounding  flood-plains.  The  silt 
forming  the  San  Francisco  valley  is  similar  to 
that  of  the  Danta,  but  will  be  found  considerably 
firmer.  In  the  San  Francisco  hills,  the  points  of 
which  are  cut  by  the  canal  line,  basalt  again 
forms  the  surface  rock.  The  records  of  six  holes 
drilled  by  the  Canal  Company  on  the  line  near 


the  one  given  in  the  section  have  been  utilized. 
As  elsewhere  they  give  only  a  minimum  meas- 
ure of  the  residual  clay.  They  may  in  some 
cases  extend  a  short  distance  into  the  soft  rock, 
but  there  is  nothing  in  the  record  to  indicate  it^ 
The  section  is  drawn,  therefore,  largely  by  in- 
ference from  the  depth  to  which  the  rock  decay 
has  been  found  extending  elsewhere  under  simi- 
lar conditions.  Numerous  boulders  will  be  en- 
countered almost  from  the  surface,  and  these  will 
increase  in  size  and  abundance  downward  until 
they  merge  with  the  solid  rock.  It  is  not  prob- 
able, however,  that  any  considerable  body  of 
solid  rock  will  be  encountered  in  cutting  the 
points  of  these  hills.  From  the  San  Francisco 
to  the  Tambor  Grande  hills  the  line  crosses  a 
level  alluvial  plain,  while  the  surface  of  the  resi- 
dual clay  passes  entirely  below  excavation. 
Since  the  line  is  near  the  river  the  silt  will 
doubtless  be  found  much  firmer  than  that  en- 
countered in  the  San  Francisco  valley.  At 
some  points  between  the  San  Francisco  and 
Tambor  Grande  hills  the  basalt  disappears,  and 
the  latter  are  composed  entirely  of  dacite  which 
extends  at  least  120  feet  below  sea  level,  and 
possibly  much  farther. 

As  already  indicated,  this  rock  weathers  in  a 
manner  quite  different  from  basalt.  The  decay 
proceeds  downward  from  the  surface,  and  no 
sharply  defined  residual  boulders  remain  either 
in  the  clay  or  the  underlying  soft  rock.  There 
is  a  gradual  transition  from  the  surface  down- 
ward, and  the  division  between  the  different 
classes  of  material  is  to  a  large  extent  arbitrary. 
As  elsewhere,  however,  the  rock  is  considered 
hard  only  when  it  will  give  a  practically  contin- 
uous core  with  the  diamond  drill.  As  shown  on 
the  section  on  which  estimates  have  been  based, 
the  upper  zone  of  residual  clay  is  thinner  and  the 
intermediate  zone  of  soft  rock  is  thicker  than  in 


APPENDIX   II.—GEOLOGIC   REPORT 


179 


basalt.  While  the  borings  from  which  these 
thicknesses  were  taken  were  on  the  point  of  the 
ridge  at  the  Tambor  Grande  dam  site,  at  some 
distance  from  the  line,  the  classification  given  in 
the  section  may  be  accepted  with  a  fair  degree 
of  confidence. 

At  some  point  between  the  Tambor  Grande 
and  Tamborcito  hills  occurs  another  change  in 
the  rocks,  and  the  dacite  of  Tambor  Grande  gives 
place  to  basalt  in  the  Tamborcito  hills.  At  the 
water's  edge  in  the  point  of  the  hills  there  is 
exposed  a  coarse  volcanic  breccia.  The  constit- 
uents vary  in  size  from  the  smallest  fragments 
np  to  angular  blocks  two  or  three  feet  in  diame- 
ter. The  matrix  is  finely  comminuted  rock  and 
volcanic  ash  and  is  only  slightly  softer  than  the 
enclosed  fragments.  The  rock  as  exposed  at  the 
water's  edge  appears  to  be  almost  perfectly 
fresh.  This  breccia  does  not  extend  far  above 
the  level  of  the  rivier,  for  at  numerous  points  on 
the  sides  and  top  of  the  ridge  are  exposures  of 
weathered  basalt  with  numerous  fresh  boulders. 
Two  alternative  lines  have  been  located  across 
the  point  of  these  hills.  Line  A  curves  to  the 
south,  crossing  a  bend  in  the  river,  the  center 
line  nearly  touching  the  point  of  Tamborcito 
island.  Line  B  cuts  directly  across  the  ridge, 
the  highest  point  on  the  center  line  being  360 
feet  above  sea  level.  Xo  borings  have  been 
made  directly  upon  either  of  these  lines,  but  a 
few  were  made  by  the  Canal  Company  on  the 
point  of  the  ridge  between  the  two  lines,  'fhey 
di<l  not  penetrate  the  rock,  however,  and  afford 
little  information  concerning  the  character  of 
material  wliich  would  be  encountered  in  excava- 
tion. The  classification  of  materials  as  repre- 
sented on  the  sections  is  taken  chiefly  by  infer- 
ence from  the  conditions  found  at  Ochoa,  where 
the  character  of  the  rocks  is  somewhat  similar. 
The  classification  must,  therefore,  be  taken  with 


considerable  allowance,  and  the  relative  propor- 
tions of  the  three  classes  of  material  may  be 
found  quite  different  from  that  represented. 
The  section  represents,  however,  the  best  infor- 
mation available  at  the  present  time.  On  line 
A  the  hard  rock  is  represented  as  reaching  a  few 
feet  above  the  flowage  line  of  the  canal,  involv- 
ing an  excavation  of  about  thirty-two  feet  in  this 
material.  Above  this  is  represented  a  maxi- 
mum thickness  of  foily  feet  of  soft  rock  and 
forty  feet  of  residual  clav.  As  elsewhere  the 
slopes  of  the  upper  surface  of  soft  rock  and  hard 
rock  each  become  successivelv  flatter  than  the 
preceding.  On  the  alternate  line  B  which 
crosses  the  ridge  near  its  highest  jx^int  the  resi- 
dual clay  is  represented  with  a  thickness  of 
seventy-three  feet.  This  may  be  an  extreme 
thickness,  but  has  been  observed  under  similar 
conditions  elsewhere.  The  soft  rock  is  repre- 
sented with  the  same  thickness  as  on  the  other 
line.  The  hard  rock  is  sliown  reaching  to  an 
elevation  of  260  feet.  The  excavation  of  this 
line  would  thus  involve  a  cut  of  230  feet  in  hard 
rock,  and  the  character  of  the  rock  is  such  that 
the  excavation  would  be  expensive. 

From  Tamborcito  to  Sarapiqui  the  line  crosses 
a  broad  alluvial  plain  in  which  the  surface  of  the 
residual  material  probably  passes  far  below  the 
excavation  line. 

The  proposed  location  across  the  Sarapiqui 
hills  follows  the  location  made  by  the  Canal 
Company.  Fourteen  holes  were  put  down  by 
the  Canal  Company  on  the  line  across  these  hills. 
The  work  was  done,  however,  with  an  earth 
auger  and  does  not  in  any  case  penetrate  the 
rock.  Rock  is  in  places  reported,  but  there  is 
no  indication  that  it  was  not  a  boulder,  and  it  is 
probable  that  the  surface  of  the  hard  rock  was 
nowhere  reached.  The  information  afforded  by 
these  borings  has  been  utilized  in  drawing  the 


180 


NICARAGUA  CANAL  COMMISSION 


sections,  but  they  are  at  best  very  unsatisfactory, 
and  an  inference  from  the  conditions  found  else- 
where is  in  general  considered  more  reliable. 
The  hills  are  composed  entirely  of  basalt  as  de- 
termined by  numerous  residual  boulders. 
Where  the  point  of  the  hills  is  cut  by  the  river 
opposite  the  mouth  of  the  Sarapiqui,  the  boulders 
are  very  abundant  and  some  of  the  outcrops  may 
represent  bedrock  in  place.  Considerable  hard 
rock  will  be  encountered  in  this  cut,  and  the  pro- 
portion of  hard  rock  may  possibly  be  somewhat 
larger  than  is  represented  in  the  section, 
although  the  latter  is  considered  a  liberal  esti- 
mate. *  Unless  the  alternate  line  B  located  across 
the  Tamborcito  hills  is  selected,  this  is  the  first 
point  upon  the  low-level  line  where  any  con- 
siderable volume  of  rock  would  be  excavated 
suitable  for  constructing  dams  or  for  making 
concrete.  As  elsewhere  in  regions  underlain  by 
basalt,  residual  boulders  will  be  found  in  increas- 
ing abundance  from  the  surface  downward  to 
hard  rock. 

After  leaving  the  Sarapiqui  hills  the  line  re- 
mains in  the  San  Jiian  flood-plain  where  the  ex- 
cavation will  be  entirely  in  silt  until  the  hills 
north  of  Buena  Vista  are  reached,  where  a  lock 
is  located.  A  number  of  borings  were  made  by 
the  Canal  Company  in  this  region,  but  they  give, 
as  elsewhere,  only  a  minimum  measure  of  the 
residual  clay  and  afford  no  information  con- 
cerning the  maximum  depth  of  either  clay  or 
soft  rock.  The  rock  of  the  region  is  entirely 
basalt,  and  the  classification  of  materials  given 
on  the  section  is  derived  chiefiy  by  inference 
from  other  regions  where  conditions  are  similar. 
It  is  probable  that  no  hard  rock  will  be  en- 
countered either  in  the  canal  excavation  or  in 
excavation  for  the  lock  foundations.  The  latter, 
however,  will  be  upon  soft  rock  which  will 
doubtless  be  sufficientlj^  solid  for  the  purpose. 


After  leaving  the  site  of  lock  No.  3  the  line 
crosses  a  few  low  hills  in  which  residual  clay  only 
will  be  encountered,  and  then  passes  to  the  allu- 
vial plain  of  the  Rio  Xegro.  Here  the  excavation 
w^ill  be  chiefly  in  silt,  with  some  residual  clay, 
and  possibly  also  soft  rock  where  the  spurs  from 
the  adjoining  hills  project  into  the  valley.  In 
the  lower  portion  of  the  valley  of  the  Rio  Xegro 
the  excavation  will  be  chiefly  in  residual  clay 
with  possibly  a  small  amount  of  soft  rock. 
Across  the  flood-plain  of  the  San  Juanillo  the 
material  will  be  silt  until  the  hill  is  reached 
which  forms  the  divide  between  the  San  Juanillo 
and  the  Misterioso.  From  this  point  to  the  next 
lock  site  the  excavation  will  be  partly  in  resi- 
dual clay,  but  probably  no  hard  rock  will  be 
encountered.  This  lock  (No.  2)  has  not  been 
actually  located  on  the  ground  and  the  topog- 
raphy from  which  the  profile  was  taken  is 
largely  hypothetical.  The  classification  of  the 
materials  partakes  of  the  same  uncertainty  as 
the  topography.  No  boring  has  been  done 
nearer  this  locality  than  at  a  point  five  miles  dis- 
tant, and  the  character  of  the  rock  is  not  accu- 
rately known.  It  is  presumed,  however,  to  be 
basalt  such  as  is  exposed  at  various  points  along 
the  San  Juanillo  and  in  the  hills  about  Lake 
Silico  a  few  miles  to  the  south.  The  geological 
conditions  represented  on  the  section  at  the  site 
of  lock  No.  2  are  taken  by  inference  from  those 
observed  under  similar  conditions  elsewhere. 
The  residual  clay  is  represented  with  a  maxi- 
mum depth  of  thirty  feet  at  the  top  of  the  ridge 
and  the  soft  rock  with  a  depth  of  thirty-five 
feet.  The  hard  rock  is  represented  as  reaching 
above  the  center  of  the  lock  excavation,  so  that 
if  the  conditions  are  as  represented  the  lock  will 
rest  upon  a  foimdation  of  solid  rock  throughout 
its  entire  extent.  It  must  be  clearly  understood, 
however,  that  the  section  represents  only  a  fair 


APPENDIX  II.— GEOLOGIC  REPORT 


181 


degree  of  probability  and  that  conditions  may- 
be found  entirely  different  from  those  which 
have  been  assumed. 

Bevond  these  hills  the  line  enters  the  alluvial 
plain  through  which  the  Misterioso  meanders, 
passing  a  succession  of  lagoons  and  deep  swamps. 
The  surface  material  here  will  be  very  soft  mud 
which  is  replaced  at  moderate  depths  by  rather 
compact  sandy  clay  silt.  The  last  lock  (No.  1) 
is  located  on  a  low  hill  which  rises  above  the  allu- 
vial plain  of  the  Misterioso.  The  information 
available  with  regard  to  the  topography  and 
geolog\'  of  this  site  is  similar  to  that  of  lock  No. 
2.  The  topography  is  only  approximate,  and  no 
examination  has  been  made  of  the  geology  by 
boring  or  otherwise.  The  conditions  represented 
on  the  section,  therefore,  must  be  taken  with 
considerable  allowance.  It  is  quite  possible  that 
both  the  residual  clay  and  the  soft  rock  will  be 
found  much  deeper  than  represented,  so  that  no 
hard  rock  may  be  found  at  the  depth  to  which 
excavation  for  the  lock  foundations  will  go. 

The  second  variant  of  the  Lull  route  passes 
through  Lake  Silico  while  the  third  passes  to  the 
south  of  the  lake.  The  statements  made  in  the 
above  paragraph  concerning  the  geology  of  Va- 
riant I  to  the  north  of  the  Silico  hills  and  east 
of  the  San  Juanillo  apply  equally  well  to  the 
Variants  II  and  III  except  that  they  should  be 
supplemented  with  regard  to  one  point.  This 
is  the  region  immediately  adjacent  to  Lake  Silico. 
Although  no  boring  was  done  in  this  vicinity 
opportunity  was  afforded  for  examining  the  geo- 
logical conditions  by  the  cuts  on  the  railroad  now 
in  process  of  construction.  The  same  deep  rock 
weathering  observed  at  other  points  was  found 
here,  and  the  conditions  are  essentially  the  same 
as  elsewhere  except  that  at  one  point  beds  of 
clay  and  sand  with  fragments  of  plants  were 
found  apparently  underlying  a  lava  flow.    These 


beds  are  somewhat  distinctly  stratified  and  ap- 
pear to  have  been  deposited  in  quiet  water,  pos- 
sibly a  lake  basin.  They  are  entirely  uncon- 
solidated and  so  far  as  could  be  observed  were 
not  materially  affected  by  the  lava  flow  which 
has  covered  them.  In  the  railroad  cut  the  clay 
beds  show  a  decided  tendency  to  slip.  If  these 
beds  continue  to  the  southeastward  near  the 
level  at  which  they  are  exposed  at  the  edge  of 
the  lake,  their  upper  surface  will  be  considerably 
above  the  bottom  of  the  canal.  If  they  are 
found  in  this  position  it  is  probable  that  they 
will  occasion  considerable  trouble  in  excavating 
and  maintaining  the  canal.  They  will  tend  to 
slip  out  from  beneath  the  lava  and  by  sapping 
it  permit  the  overlying  rock  to  fall  down. 

The  proflle  indicates  that  a  lock  is  planned  at 
this  point  If  the  beds  of  clay  have  any  con- 
siderable thickness,  as  is  altogether  probable, 
they  would  afford  an  insecure  foundation  for  a 
lock.  On  the  profile  these  beds  have  not  been 
represented  on  account  of  the  lack  of  exact  in- 
formation concerning  them,  but  conditions  have 
been  represented  as  they  would  probably  be 
found  if  the  lava  forming  the  surface  continued 
indefinitely  downward.  The  presence  of  the 
beds,  however,  and  the  probability  that  they  ex- 
tend some  distance  to  the  southwestward  should 
be  taken  into  account  in  deciding  upon  the  rela- 
tive merits  of  alternative  routes  in  this  region. 

Practically  the  same  geological  conditions 
will  be  met  on  the  Variants  I,  II  and  III,  across 
the  alluvial  delta  plain  between  the  last  residual 
hills  and  the  coast.  As  already  stated  the  inner 
portion  of  this  delta  plain  is  covered*  by  a  layer 
of  fine  clay  silt  or  swamp  mud  overlying  sand  or 
sandy  clay.  The  layer  of  mud  thins  out  toward 
the  coast,  and  the  outer  margin  of  the  delta  plain 
is  composed  entirely  of  sand.  The  lagoons 
which  are  crossed  by  these  lines  in  the  delta 


182 


NICARAGUA  CANAL  COMMISSION 


plain  have  already  been  described.  They  con- 
tain occasional  small  bodies  of  open  water,  but 
are  generally  in  a  somewhat  advanced  stage  in 
the  process  of  silting  up  and  where  the  larger 
trees  have  not  yet  secured  a  footing  are  occupied 
by  coarse  grass  and  Silico  palms.  Low  slopes 
will  be  required  through  the  more  open  of  these 
lagoons,  and  all  the  alluvium  excavated  will 
probably  be  sufficiently  firm  to  stand  in  banks 
with  steep  slopes  when  it  has  an  opportunity  to 
become  thoroughly  drained.  With  the  con- 
struction of  the  canal  the  water  surface  in  the 
lagoons  will  be  materially  and  permanently  low- 
ered so  that  much  of  the  surface  now  covered 
with  water  will  be  comparatively  dry  and  firm. 
The  extent  of  this  drainage  will  of  course  be  in 
proportion  to  the  porosity  of  the  silt  which  in 
turn  depends  on  the  proportion  of  sand  which  it 
contains.  The  change  which  will  follow  the  ex- 
cavation may  be  seen  in  the  vicinity  of  the  short 
section  of  canal  dredged  by  the  Canal  Company. 
The  land  at  some  distance  on  either  side  of  the 
ditch  is  perceptibly  firmer  than  elsewhere  in  the 
same  region. 

The  behavior  of  the  sand  which  forms  the 
outer  margin  of  the  delta  plain  when  deposited 
in  banks  alongside  an  excavation  is  seen  where 
dredging  has  been  done  at  Greytown.  The 
sand  is  so  porous  that  water  falling  upon  it  is  at 
once  absorbed  and  consequently  does  not  gully 
the  steepest  slopes. 

ADDITIONAL  GEOLOGIC  WORK  RE- 
QUIEED  FOR  FINAL  LOCATION. 

The  geological  work  done  under  the  direction 
of  the  U.  S.  Nicaragua  Canal  Commission  is 
sufficient  for  the  preliminary  location  and  pre- 
liminary estimates  of  cost.  Before  the  final  lo- 
cation can  be  made  considerable  additional  in- 


formation should  be  secured.  This  required 
information  will  be  obtained  chiefly  by  means 
of  drills,  although  some  additional  general  geo- 
logical work  might  well  be  carried  on  with 
advantage.  This  is  generally  true  of  the  work 
which  it  has  been  proposed  to  do  at  greater  or 
less  distance  from  the  line  of  the  canal  for  the 
purpose  of  obtaining  information  which  will  be 
of  use  for  the  selection  of  the  best  materials  to 
be  used  in  construction  and  for  protecting  the 
works  when  completed. 

The  work  with  earth  auger  and  diamond  drill 
may  be  divided  into  two  general  classes;  first, 
that  needed  for  the  classification  of  materials  on 
excavation  lines,  and,  second,  that  needed  for 
the  determination  of  the  character  of  founda- 
tions for  structures  such  as  locks,  dams  and 
weirs.  Less  of  the  former  class  of  work  will 
be  required  than  of  the  latter. 

On  Excavation  Lines. — More  or  less  work 
should  be  done  at  the  following  named  locali- 
ties: At  Brito,  while  it  is  probable  that  if  the 
harbor  be  located  toward  the  south  side  of  the 
Rio  Grande  valley  no  rock  will  be  encountered, 
still  there  is  no  certainty  of  this,  and  a  sufficient 
number  of  test  borings  should  be  made  to  deter- 
mine this  point  definitely.  If  these  borings  are 
carried  to  a  considerable  depth  below  the  pro- 
posed bottom  of  the  harbor  the  number  required 
\vill  be  fewer  than  if  thev  are  carried  down 
barely  to  the  depth  of  the  proposed  excavation. 

Borings  should  be  continued  along  the  line  of 
the  canal  on  the  west  side  at  intervals  not 
greater  than  a  thousand  feet,  and  wherever  the 
line  approaches  the  edge  of  the  valley  they 
should  be  put  down  at  intervals  of  three  to  five 
hundred  feet.  This  work  should  be  continued 
entirely  to  the  lake  for  the  purpose  of  making 
an  accurate  classification  of  the  material  to  de- 
termine the  methods  of  excavation,  and  the  slope 


APPENDIX  II.— GEOLOGIC  REPORT 


183 


at  which  the  material  will  stand  and  hence  the 
amount  of  excavation,  these  two  elements  chiefly 
determining  the  cost. 

Coming  to  the  east  side  of  the  lake  additional 
work  should  be  done  on  the  river  from  the  lake 
to  the  point  where  the  canal  leaves  the  river 
channel.  Between  the  lake  and  the  Toro  rapids 
a  series  of  transverse  sections  should  be  deter- 
mined by  means  of  the  drill  in  order  to  deter- 
mine more  definitely  the  slope  of  the  rock  sur- 
face which  the  work  already  done  has  discov- 
ered. This  will  be  necessary  before  the  most 
advantageous  location  of  the  canal  line  can  be 
made.  Special  attention  should  be  paid  to  the 
Toro  rapids  and  sufficient  work  done  at  this 
point  to  locate  the  old  river  channel  through  this 
obstruction  if  such  a  channel  exists.  Between 
the  Toro  rapids  and  the  Boca  San  Carlos  little 
work  will  be  required  except  on  proposed  cut- 
offs. The  extent  of  the  work  will  be  deter- 
mined somewhat  by  the  plan  which  is  adopted 
and  the  consequent  grade  of  the  canal  between 
Machuca  and  the  San  Carlos. 

Assuming  that  the  low-level  line  is  decided 
upon,  which  leaves  the  river  channel  at  the  Boca 
San  Carlos,  boring  should  be  done  at  a  number 
of  localities  between  this  point  and  Greytown. 
The  greater  part  of  the  work  would  naturally 
be  where  the  excavation  was  heaviest;  that  is, 
where  the  line  crosses  the  points  of  hills  which 
extend  down  to  the  San  Juan  river.  The  object 
of  this  work  would  be,  as  on  the  west  side,  to 
determine  the  character  of  the  materials,  and 
hence  the  methods  which  can  be  employed  in 
excavation,  and  the  slopes  of  the  excavation.  A 
further  purpose  which  would  be  served  by  care- 
ful and  systematic  boring  on  these  points  would 
be  to  determine  the  availability  of  the  material 
which  will  be  excavated  for  structural  purposes 
on  other  parts  of  the  line.     If  the  rock  is  not  of 


such  a  character  as  to  form  suitable  material  for 
concrete  and  rip-rap  it  will  be  necessary  to  search 
for  such  material  elsewhere.  Systematic  boring 
should  be  done  wherever  the  canal  line  crosses 
alluvial  plains  at  such  an  elevation  that  a  con- 
siderable embankment  will  be  required,  in  order 
to  determine  •  the  character  of  the  silt  and 
whether  or  not  it  will  form  a  water-tight  em- 
bankment without  a  clay  core. 

On  Foundations. — No  work  has  been  done  on 
the  west  side  except  at  La  Flor,  with  the  distinct 
object  of  determining  the  character  of  founda- 
tions for  locks  and  dams.  If  a  low-level  route 
is  adopted  on  the  west  side  systematic  examina- 
tion should  be  made  of  the  character  of  the  foun- 
dations at  the  various  points  where  locks  will  be 
located.  The  information  at  hand  concerning 
this  region  is  ample  for  preliminary  location  and 
plans,  but  considerable  additional  information 
should  be  obtained  before  the  final  plans  are 
adopted.  The  drilling  operations  will  prob- 
ably show  that  in  some  cases  the  location  of  the 
lock  sites  can  be  shifted  with  advantage,  since  it 
is  not  probable  that  the  site  selected  purely  on 
account  of  topographic  considerations  will  in 
every  case  afford  the  best  foundation.  The 
point  selected  for  a  dam  and  controlling  works 
in  the  upper  portion  of  the  Rio  Grande  valley 
should  be  systematically  examined,  and  the  sec- 
tions which  have  been  based  chiefly  upon  sur- 
face examinations  should  be  carefully  verified 
by  drilling. 

Sufficient  work  has  been  done  on  the  various 
possible  dam  sites  on  the  San  Juan  river  to  af- 
ford a  basis  for  preliminary  location  and  to  de- 
termine the  relative  merits  of  the  various 
schemes  which  involve  construction  of  dams  at 
one  or  more  of  these  localities.  When  the  plan 
which  appears  most  favorable  has  been  selected, 
the  dam  sites  which  it  involves  should  be  exam- 


184 


NICARAGUA  CANAL  COMMISSION 


ined  with  ^  great  thoroughness  before  the  final 
plans  are  adopted.  Even  at  the  Ochoa  site 
where  the  most  thorough  work  has  been  done, 
considerable  additional  work  would  be  required. 
Most  of  the  boring  done  was  confined  to  a  single 
line,  approximately  the  center  line  of  the  dam, 
but  it  is  evident  that  the  entire  arej  which  would 
be  covered  by  the  foundation  of  the  dam  should 
be  thoroughly  examined.  At  the  other  sites  this 
additional  work  is  even  more  important.  No 
boring  has  been  done  on  the  east  side  at  any 
locality  which  will  probably  be  finally  selected 


for  the  lock  sites.  The  sections  which  have 
been  submitted  showing  the  geological  condi- 
tions at  the  various  suggested  lock  sites  are 
chiefly  derived  by  inference  from  other  locali- 
ties where  examination  has  been  made.  While 
this  inference  is  perhaps  sufficient  for  prelimi- 
nary location,  its  weakness  has  been  pointed  out 
in  the  foregoing  report,  and  no  final  location  or 
final  plans  should  be  made  imtil  a  thorough  ex- 
amination has  been  made  by  means  of  the  drill 
of  the  exact  conditions  below  the  surface. 


PART  III 

MICROSCOPIC  PETROGRAPHY  OF  THE  ROCKS 
FROM  THE  NICARAGUA  CANAL  REGION 

By  F.  LESLIE  RANSOME 

y4sst.  Geologist,  U.  S.  Geological  Survey 


The  following  notes  make  no  pretense  of  be- 
ing exhaustive.  They  merely  record  observations 
made  on  the  hand-specimens  and  their  sections, 
unconfirmed  by  chemical  examination.  The 
feldspars  have  been  determined  by  the  methods, 
of  Michel  Levy,  Fouque,  and  Becke.  It  is  evi- 
dent that  some  of  the  volcanic  rocks  described 
are  close  to  the  line  between  augite-andesites  and 
olivine-free  plagioclase  basalts.  In  such  cases 
chemical  examination  might  result  in  placing 
with  the  basalts  one  or  more  of  the  andesites  of 
the  following  table,  or  vice  versa.  Although 
in  many  cases  collected  from  residual  boulders 
in  clay,  the  massive  volcanic  rocks  are  usually 
strikingly  fresh,  showing  that  the  active  trans- 


formation, from  rock  to  soil  or  clay,  is  often 
confined  to  a  very  narrow  zone.  The  passage 
from  clay  to  fresh  rock  would  seem  to  be  re- 
markably  sharp  as  compared  with  the  weather- 
ing which  takes  place  in  temperate  regions. 

In  their  general  character,  the  volcanic  rocks 
resemble  those  described  by  Hague  and  Iddings  * 
from  San  Salvador.  The  rocks  of  both  regions 
range  from  acid  to  basic  varieties.  The  basalts 
and  andesites  are  frequently  hypersthene-bear- 
ing,  and  dacites  occur  which  possess  both  ande- 
sitic  and  rhyolitic  features. 

March  18,  1899. 

1  Notes  on  the  Tolcanic  rocks  of  the  Republic  of  Salva- 
dor.    Am.  Jour.  Sci.,  Vol.  XXXII,  1886,  pp.  26-30. 


APPENDIX  II.— GEOLOGIC  REPORT 


185 


Number  ; 

of 
Specimen. 


Name. 


7-a    !  Hypersthene- 
basalt. 


14     '  Olivine-basalt. 


15-a 


Hypersthene- 
basalt. 


33-a 


Basalt 
(glassy). 


35 


Olivine-basalt. 


Locality. 


Description. 


San  Carlos  embankment 
Line,  2J  miles  S.  of 
Upper  Oehoa  dam  site. 
Kesidnal  boulders  in 
red  clav. 


Upper  Ochoa  dam  site, 
200  feet  below  center 
line,  S.  bank  of  Kio 
San  Juan.  Kesidnal 
boulder  in  clay  forming 
bluff  above  hole  No.  7 ; 
15  to  25  feet  above 
river. 


Upper    Ochoa,   bank    of , 
Caflo  Benito;   500   ft. 
S.  of  Kio    San   Juan ;  ' 
residual  boulder  in  red  i 
clay. 


Southern  point  of  Tam- 
borcito  hills.  Exposed 
at  low  water  on  N. 
bank  of  Rio  San  Juan. 
Coarse   volcanic    brec- 


cia. 


Buena  Vista;  3  miles 
below  Boca  Sarapiqni 
cleared  hill  on  N.  bank 
of  Rio  San  Juan.  Re- 
sidual boulder  in  red 
clay. 


Megascopically :  Dark,  nearly  aphanitic,  of 
basaltic  aspect.  Weathers  superficially  to 
a  yellow  ocherous  crust. 

Microscopically:  Porphyritic  structure,  with 
nearly  holocrystalline  fluidal  groundmass. 
Essential  constituents  are  basic  plagioclase 
(labradorite  or  anorthite)  >•  hyperstnene  >• 
aiigite  ^  olivine,  and  a  little  glass.  Acces- 
sory iron  ore  and  apatite.  Olivine  serpenti- 
nized. 

Megascopically :  Dark  grey  and  fine-grained, 
with  small  phenocrysts  of  olivine.  W  eathers 
light  grey  and  then  ocher  yellow. 

Microscopically  :  Porphyritic ;  phenocrysts  of 
olivine  in  nearly  holocrystalline  intersertal 
groundmass.  Essential  constituents  are 
Basic  plagioclase  (labradorite  or  anorthite)  >• 
pale  greenish  augite  ]>  olivine  >•  glass.  Ac- 
cessory iron  ore,  apatite,  and  minute  prisms 
of  an  undetermined  brown  mineral. 

Megascopically :  Dark,  heavy,  even-textured 
rock  of  doleritic  aspect.  Weathers  to  an 
ocherous  crust. 

Microscopically  :  Nearly  holocrystalline  doler- 
itic structure.  Basic  labradorite  ]>  augite  X 
hypersthene]>  glass.  Accessory  apatite  and 
iron  ore.  Secondary  serpentine,  probably 
from  alteration  of  olivine  phenocrysts. 

Megascopically :  Dark  and  basaltic,  with  small 
phenocrysts  of  feldspar,  and  green  specks  of 
chlorite. 

Microscopically  :  Porphyritic  structure.  Small 
phenocrysts  of  basic  labradorite  or  anorth- 
ite ]>  augite  ^  iron  ore,  in  a  fine  groundmass 
of  plagioclase  microlites,  iron  ore  and  glass. 
Amygdules  of  chlorite,  and  opal  (?). 

Megascopically:  Ordinary  olivinitic  basalt. 

Microscopically :  Porphyritic  with  holocrystal- 
line groundmass.  Phenocrysts  of  basic  lab- 
radorite or  anorthite  ^  olivine  ^  augite. 
Groundmass :  Augite  ]>^  iron  ore  ]>  pla- 
gioclase. Groundmass  is  unusually  rich  in 
augite.  Olivine  partly  resorbed  and  usually 
serpen  tinized. 


186 


NICARAGUA  CANAL  COMMISSION 


Number 

of 
Specimen. 


38 


44 


50 


81 


82 


84 


Name. 


Olivine-basalt. 


Hypersthene- 
baealt. 


46      i  Olivine-basalt. 


Hyperethene- 
andesite. 


Locality. 


Machado ;  1  mile  N.  SO*' 
W.  from  Upper  Ochoa 
dam  site.  Boulder  in 
small  brook,  nearly  in 
place. 

San  Carlos  hills,  about  1 
mile  N.  AV.  of  Boca 
San  Carlos,  1000  ft.  A. 
T.;  top  of  bench  on  a 
narrow  spur.  Residual 
boulder  in  red  clay. 


Castillo ;  steep  rounded 
hill  on  S.  bank  of  Rio 
San  Juan.  Rock  ledge 
in  place. 


Granada ;  from  quarry 
W.  of  town  ;  used  as  a 
building  stone. 


Hypersthene- 
andesito 
pumice. 

Hypersthene- 
andesite. 


Olivine-basalt 

(glassy). 


Volcano  Ometepe;  near 
top  of  cone  on  west  side. 
Loose  block  in  ash. 

Volcano  Ometepe ;  large 
blocks  of  lava  in  loose 
ash  at  highest  point  of 
crater  rim. 


Volcano  Ometepe;  lava 
flow  on  west  side  near 
base. 


Description. 


Megascopically :  Dark  grey,  nearly  aphanitic. 

Microscopically:  Porphyritic structure.  Phen- 
ocrysts  of  olivine  ^]>  biotite.  Groundmass 
of  augite  >•  plagioclase  X  glass  >•  iron  ore. 
Biotite  is  in  ragged  plates. 

Megascopically:  Grey,  even-grained,  and  ap- 
parently holocrystalline. 

Microscopically :  Holocrystalline  porphyritic 
structure;  phenocrysts  grade  into  ground- 
mass.  Essential  constituents:  basic  labra- 
dorite^  augite  X  hypersthene.  Accessory 
iron  ore,  biotite  and  apatite. 

Megascopically :  Minute  phenocrysts  of  feld- 
spar in  an  aphanitic,  dark  grey  oase. 

Microscopically :  Porphyritic  structure  with 
fine,  rather  glassy  groundmass.  Olivine 
altered  to  iddingsite  pseudomorphs. 

Megascopically :  Light  grey  and  of  porous 
texture. 

Microscopically :  Porphyritic, with  hyalopilitic 
groundmass.  Essential  constituents  labra- 
dorite>'augiteXhypersthene]> brown  horn- 
blende, and  abundant  glass.  Accessory  iron 
ore,  apatite  and  tridymite. 

Megascopically :  A  dark  grey,  vesicular  glass. 
Microscopically :   Phenocrysts   of   labradorite 
and  hypersthene  in  a  microlitic  glass. 

Megascopically :  Nearly  black  pitchstone, 
showing  small  phenocrysts  of  feldspar.  Is 
somewhat  pumiceous. 

Microscopically  :  Hyalopilitic  structure.  Es- 
sential constituents  are  labradorite^  hypers- 
thene >•  augite  (in  groundmass),  with  abun- 
dant brown  glass.     A  beautifully  fresh  rock. 

Megascopically  :  Dark  grey  vesicular,  glassy 

rock  of  andesitic  aspect. 
Microscopically :    Vesicular    and    porphyritic 

structure.    Phenocrysts  of  basic  labradorite 

»olivine]>  augite,  in  a  turbid  microlitic 
.  glass.     There  is  perhaps  a  little  hypersthene 

present. 


APPENDIX  II.— GEOLOGIC  REPORT 


187 


Number 

of 

Spocimcn. 


88 


91 


109 


115 


120 


123 


Nanio. 


Diorite  (?) 
(altered). 


Quartz-diorite 
(altered). 


Hyperethene- 
andesite. 


HyperBthene- 
audesite. 


Hyperstliene- 
I      andesite 
(\'itrophyre). 


l/ocality. 


Description. 


Hyperstliene- 
basalt 
(vitropliyric). 


Machiica  dam  site;  Cam- 
pafla  island ;  i  mile 
below  Maehiica.  Large 
boulders  at  head  of 
island  from  dike;  nearly 
in  place. 

Maehuca  dam  site ;  center 
line  200  ft.  S.  of  Rio 
San  Juan.  Residual 
boulder  in  red  clay. 


Lake  Apoya ;  inner  slope 
of  caldera  basin  ;  lava 
flow  associated  with 
ash-beds. 


Ravine  IJ  miles  S.  W.  of 
La  Flor  dam  site ;  dike 
in  Brito  sandstone. 


Rio  Grande  valley;  north 
side;  on  Childs  route 
variant  II,  Sta.  503, 
near  hole  No.  4.  Rock 
ledge  in  place. 


Escalante    river;    about 
50    miles     N.    W.    of 
Brito    on    the    Pacific 
coast.     Residual  boul- 
der in  black  clay  soil. 


Megascopically :  Fine-grained,  holocrystalline 
grey  rock,  with  slight  porphyritic  develop- 
ment of  hornblende.  / 

Microscopically :  An  altered  holocrystalline 
granular  rock — probably  once  a  diorite. 
Epidote  is  very  abundant. 

Megascopically :  A  rather  fine-grained  gran- 
ular rock  of  dioritic  aspect,  with  abundant 
specks  of  pyrite. 

Microscopically:  An  altered  quartz  diorite, 
full  of  secondary  minerals.  It  may  have 
been  an  augite-diorite  originally,  as  horn- 
blende is  green  and  fibrous. 

Megascopically:  Light  grey  and  porous,  with 
small  phenocrysts  of  plagioclase  and  horn- 
blende. ' 

Microscopically :  Por])hyritic  structure  with 
hyalopilitic  groundmass.  Phenocrysts  of 
labraaorite]>  hypersthene>  greenish  aug- 
ite]>  hornblende.  Groundmass  of  feldspar 
laths,  augite,  iron  ore,  and  much  glass. 

Megascopically :     Compact    dark   grey,   with 

numerous  small  phenocrysts  of  plagioclase. 

Microscopically :    Porphyritic   structure   with 

f>ilotaxitic  groundmass.  Phenocrysts  of 
abradorite  (Abg  An4)  >  augite  ]>  hypers- 
thene.  Augite  and  hypersthene  frequently 
intergrown.  Groundmass  consists  of  same 
minerals  as  phenocrysts,  with  usual  access- 
ories and  perhaps  a  little  glass. 

Megascopically  :  Abundant  small  phenocrysts 
of  plagioclase  in  nearly  black  glassy  base. 

Microscopically :   Porphyritic   structure. 
Essential   constituents   are    phenocrysts  of 
labradorite  (Ab,  An4)>  hypersthene  >•  au- 
gite, in  an  abundant  microlitic  brown  glass. 
A  fresh  and  beautiful  rock. 

Megascopically  :  Like  above,  but  apparently  a 
little  more  weathered. 

Microscopically:  Structure  vitropliyric. 

Essential  constituents  are  labradorite  (near 
Abs  A n4)]>  hypersthene ]>  pale  green  augite 
>iron  ore,  with  much  microlitic  brown 
glass.  Plagioclase  shows  beautiful  skeletal 
and  spherulitic  growths.  The  rock  may  be 
a  basic  facies  of  a  hypersthene  andesite,  but 
is  rather  rich  in  dark  minerals. 


188 


NICARAGUA  CANAL  COMMISSION 


Number 

of 
Specimen. 


Name. 


129       Olivine-baBalt. 


133     I  Basaljb 

I     (olivine-free). 


135       Aplitic  dike- 
rock. 


150 -a 


Hypersthene- 
baealt. 


159 


163-c 


Olivine-basalt. 


01  i  vine-basalt. 


Ix)cality. 


Palo  de  Arco;  on  point 
of  low  hill,  south  bank 
of  Rio  San  Juan.  Re- 
sidual boulder  in  red 
clay. 


Castillo;  hill  on  north 
bank  of  Rio  San  Juan ; 
jointed  ledge  in  place. 


Pilares  rapids ;  rock  ledge 
in  place;  exposed  at 
low  water  in  channel 
of  Rio  San  Juan;  dike 
in  Machuca  sandstone. 


San  Carlos  embankment; 
near  Cafio  Cnreno,  li 
miles  from  lower  Ochoa 
dam  site,  150  miles  N. 
E.  of  No.  7.  Rock  ledge 
in  place. 

San  Francisco  hills ;  N. 
bank  of  Rio  San  Juan, 
opposite  San  Francisco 
island.  Residual  boul- 
ders in  red  clay. 


ElTigre:  N.  bank  of  Rio 
San  Juan,  li  miles 
above  Boca  San  Carlos. 
Residual  boulder. 


Description. 


Megascopically :  Nearly  black,  with  pheno- 
crysts  of  plagioclase  and  olivine  in  a  com- 
pact base. 

Microscopically :  Porphyritic  structure,  with 
phenocrysts  distinct  from  groundmass. 
thenocrysts  of  anorthite^olivine^augite. 
Groundmass  a  fine  intersertal  aggregate  of 
augite  X  plagioclase  ^  iron  ore  X  glass. 
Olivine  is  partly  serpentinized. 

Megascopically :  Irregularly  banded  or  mot- 
tled, aphanitic  rock,  of  somewhat  purplish 
tint.  Shows  a  few  minute  phenocrysts  of 
feldspar. 

Microscopically:  Porphyritic  structure.  Small 
phenocrysts  of  anorthite  and  pale  augite,  in 
a  fine  groundmass  of  plagioclase,  augite,  iron 
ore  and  glass. 

Megascopically :  A  light  grey  porphyry  with 
small  phenocrysts  of  feldspar. 

Microscopically :  Porphyritic,  with  pheno- 
crysts of  oligoclase  and  orthoclase  (?),  in  a 
fine  granular  groundmass  of  alkali  feldspar 
and  quartz.  A  little  iron  ore  and  a  few 
biotite  scales  largely  changed  to  chlorite. 
Feldspathic  phenocrysts  are  partly  changed 
to  calcite.  Rock  is  somewhat  obscure. 
Might  be  termed  an  aplite-porphyry. 

Megascopically  :  Dark  grey  and  nearly  aphan- 
itic.    Weathers  to  an  ocherous  yellow  crust. 

Microscopically :  Essential  constituents  are 
labradorite  ]>  augite  ]>  hypersthene  ]>  glass. 
Usual  accessories.  Hypersthene  partly  ser- 
pentinized. Some  serpentine  may  have  been 
derived  from  olivine. 

Megascopically:  Dark  grey,  and  of  ordinary 

basaltic  character. 
Microscopically  :  Ordinary  olivine-basalt,  with 

olivine  largely  serpentinized. 


Megascopically :  Dark  grey,  with  small  pheno- 
crysts in  an  aphanitic  base. 

Microscopically  :  Typical  olivine-basalt  of  near- 
ly holocrystalline  doloritic  habit. 


APPENDIX  II.— GEOLOGIC  REPORT 


189 


Numlier 

of 
Specimen. 


lt)7 


Name. 


Hypersthene- 
basalt. 


Locality. 


Description. 


Tamborcito  hills;  near  Rio  i  Megascopically :  Numerous  small  pheiiocrysts 


San  Juan;  at  various 
points  on  crest  and 
sides.  Residual  boul- 
ders in  red  clay. 


169 


Basalt 
(olivine-free). 


Sarapiqui  hills;  top  of  \ 
cleared  hill,  500  ft.  from  i 
Rio  San  Juan,  opposite  i 
mouth  of  the  Sarapiqui. 


173 


Basalt  '  Punta  Petaca;   N.  bank  | 

(olivine-free).  |      of  Rio  San  Juan ;  low  ! 

i      cleared  hill.     Residual  , 
boulders  in  red  clay. 


180 


Basalt  (prob- 
ably olivine- 
basalt). 


Cafio  Deseado;  i  mile 
above  Camp  Menocal. 
Residual  boulder  in  red 
clay. 


182 


Hypersthene- 
basalt. 


Cafio  Deseado ;  Camp 
Warner  Miller.  Re- 
sidual boulder  in  red 
clay. 


185 


Enstatite- 

andesite. 


Falls  of  Luisa ;  Cafio  Des- 
eado; heavy  rock  ledge 
in  place. 


of  plagioclase  and  pyroxene  in  a  compact, 
nearly  black  groundmass. 
Microscopically :  Porphyritic  structure.  Pheno- 
crysts  of  basic  labrodorite  or  anorthite]> 
hypersthene,  in  a  fine  groundmass  of  augite, 
plagioclase  and  iron  ore,  with  abundant 
light  brown  glass. 

Megascopically:  Numerous  small  phenocrysts 
of  plagioclase  in  a  compact  dark  base. 
Weathers  to  an  ocherous  yellow  crust. 

Microscopical :  Porphyritic  structure.  Pheno- 
crysts of  anorthite  in  a  groundmass  of  pla- 
gioclase, augite,  iron  ore  and  glass. 

Megascopically:  Like  169,  but  more  crystal- 
line. 

Microscopically :  Almost  holocrystalline  doler- 
itic  structure.  Essential  constituents  are 
plagioclase  (near  by townite)  >  augite  >•  iron 
ore  ]>  glass.     Accessory  apatite. 

Megascopically:  Dark  and  basaltic  looking, 
with  abundant  small  lath-shaped  phenocrysts 
of  plagioclase.  Weathers  to  an  ocherous 
crust. 

Microscopically:  Porphyritic  structure.  Pheno- 
crysts of  anorthite  ]>  olivine  (serpentinized), 
in  a  groundmass  of  plagioclase,  augite,  iron 
ore,  and  glass. 

Megascopically :  Apparently  a  doleritic  basalt. 

Microscopically  :  Porphyritic  structure.  Phe- 
nocrysts of  basic  labradorite  or  anorthite^ 
augite  ]>  hypersthene,   in   a  groundmass  of 

flagioclase^  augite  ]>  iron  ore,  and  glass. 
8  apparently  near  the  andesites. 

Megascopically :  Dark  grey,  with  small  pheno- 
crysts of  plagioclase  augite  in  a  compact 
groundmass. 

Microscopically :  Porphyritic  structure.  Phe- 
nocrysts of  basic  labradorite  ^  augite  ]>  a 
rhombic  pyroxene  (enstatite  ?),  mostly  alter- 
ed to  serpentine.  Groundmass  is  hyalopi- 
litic,  consisting  of  plagioclase,  augite,  rhom- 
bic pyroxene  and  glass,  with  iron  ore  and 
apatite. 


190 


NICARAGUA  CANAL  COMMISSION 


Number 

of 
Specimen. , 


Name. 


Ix)cality. 


Description. 


194     I  Olivino-basalt.  i  Silico  lake;  cut  on  C.  &  ■  Megascopically :  Dark  and  compact,  with  small 


195 


P.  T.  Co.  Ry.,  i  mile 
east  of  the  lake.  Re- 
sidual boulders  in  clay. 


Olivine-basalt.    Silico  lake;  cut  on  C.  & 

P.  T.  Co.  Ry.,  i  mile 
east  of  lake.     Residual 
I      boulders  in  clay ;  intru- 
'      sive  dikes  in  194. 


202 


Augite- 

andesite(?). 


203 


Basaltic  or  an- 
desitic  tuff. 


205         Dacite. 


206        Dacite. 


Menocal  Route;  Eastern 
Divide,  core  from  hole 
No.  1,  137  feet  below 
surface. 


Menocal  Route;  Eastern 
Divide,  core  from  hole 
No.  1,  173  feet  below 
surface. 

Menocal  Route;  Eastern 
Divide,  core  from  hole 
No.  2,  16  feet  below 
surface. 


.  Menocal  Route,  Eastern 
Divide;  core  from  hole 

'  No.  2,  100  feet  below 
surface. 


phenocrysts  of  plagioclase  and  olivine. 
Microscopically :  Ordinary  olivine  basalt  with 
olivine  partly  changed  to  iddingsite. 

Megascopically :  Rather  light  grey,  locally 
vesicular.  Small  phenocrysts  of  plagioclase 
and    olivine  in    a   dense  grey  groundmass. 

Microscopically :  Like  194. 


Megascopically:  Light  grey  and  glassy,  with 
a  few  minute  dark  phenocrysts. 

Microscopically :  Structure  porphyritic  with 
hyalopilitic  groundmass.  Small  phenocrysts 
of  plagioclase  and  pseudomorphs  of  calcite 
(after  pyroxene?)  in  a  groundmass  of  feld- 
spar microlites,  glass  and  iron  ore.  Rock  is 
amygdaloidal  and  decomposed. 

Megascopically :  Apparently  a  dark  grey,  de- 
composed, basic  tuff. 

Microscopically:  Turbid  and  glassy.  Prob- 
ably a  basaltic  tuff,  but  may  be  andesitic. 

Megascopically :  A  light  grey  porphyry  show- 
ing phenocrysts  of  feldspar  and  quartz  in  a 
grey  glassy  base. 

Microscopically :  Porphyritic  structure.  Phe- 
nocrysts of  quartz  and  andesine  in  a  glassy, 
partly  devitrified  groundmass  resembling  the 
groundmass  of  many  glassy  rhyolites.  The 
character  of  the  groundmass  and  the  absence 
of  dark  constituents  give  a  decided  rhyolitie 
aspect  to  the  rock  as  seen  in  thin  section.  It 
is  placed  provisionally  with  the  dacites  on 
account  of  its  relatively  basic  plagioclase 
and  absence  of  sanidine. 

Megascopically:  Like  205,  but  contains  small 

inclusions  of  some  darker  rock. 
Microscopically:    Very    similar    to    205,  but 

contains  included  fragments    of    pyroxene 

andesite. 


209      Andesite-tuff(?)  Menocal  Route,  Eastern 

'  Divide,  core  from  hole 
No.  2,  195  feet  below 
surface. 


Megascopically :  Fragile,  grey-green  material, 
apparently  a  glassy  tuff. 

Microscopically :  A  fine  grained  augitic  pla- 
gioclase tuff — probably  andesitic. 


APPENDIX  II.— GEOLOGIC  REPORT 


191 


Numl>or 

of 
Specimen. 


Name. 


212       Limestone. 


216  Basalt  or 

augite-andesite. 


217       Dacite. 


219       Olivine-basalt. 


220        Andesite-tuft'. 


223       Dacite. 


22t>       Qlivine-basalt. 


Locality. 


San  P^rancisco  embank- 
ment; between  San 
Francisco  and  Surprise; 
core  from  hole  B5,  108 
feet  below  surface. 

Lower  Ochoa  dam  site, 
center  lino,  N.  bank  of 
liio  San  Juan ;  core 
from  hole  No.  2,  180 
feet  below  surface. 

Lower  Ochoa  dam  site; 
core  from  hole  No.  3; 
center  line  S.  bank  of 
Rio  San  Juan  ;  33  feet 
below  surface. 


Upper  Ochoa  dam  site; 
core  from  hole  No.  10, 
107  feet  below  surface ; 
top  of  hill  at  N.  end  of 
dam. 


D<»8crIption. 


Megascopically :  Light  yellow  and  plainly 
clastic. 

Microscopically:  A  very  fine-grained  lime- 
stone, containing  a  few  specks  of  iron  ore. 

Megascopically:    Like    33.      A    decomposed 

chloritized  rock. 
Microscopically:     Much    decomposed.      May 

have  been  a  basalt  or  augite  andesite. 

Megascopically  :  Dark  grey  with  small  pheno- 
crysts  of  plagioclase  and  quartz  in  a  compact 
base. 

Microscopically :  Phenocrysts  of  labradorite 
(Ab,  Aui)  and  andesine,  quartz,  and  chlori- 
tized biotite,  in  a  fine  groundmass  of  plagio- 
clase microlites  embedded  in  a  feldspathio 
base  which  extinguishes  simultaneously 
over  considerable  areas  of  the  thin  section 
giving  a  mottled  or  micropoikilitic  eflfect 
with  crossed  nicols.  The  rock  is  not  fresh 
and  may  have  contained  some  augite.  Iron 
ore  and  apatite  are  present  as  accessories. 

Megascopically:    Ordinary   appearance    of    a 

fine-grained  olivine-basalt. 
Microscopically:  Ordinary  olivine-basalt,  but 

contains  some  small    brown     prisms     like 

those  noted  in  No.  14. 


Upper   Ochoa  dam  site;    Megascopically:  Somewhat  decomposed  grey 
top  of  hill  at  N.  end  of        tuif. 

dam ;    core  from    hole    Microscopically :  Apparently   a  fine  andesitic 
No.  10,  157  feet  below  .      tuff, 
surface. 

Upper  Ochoa  dam    site;  j  Megascopically:      Light    grey,    of    rhyolitic 
center  line,  N.  bank  of        aspect,  carrying  small  dark  inclusions. 
Rio    San    Juan  ;    core  I  Microscopically  :  Porphyritic  structure.     Phe- 
from  hole  D3,  56  feet'      nocrysts  of  quartz]>  plagioclase  (near  ande- 
below  surface.  '      sine)  >]>  green    hornblende,  in   an   abun- 

dant    microlitic     and      partly     devitrified 
streaky  glass.     Probably  an  acid  dacite. 


Upper  Ochoa  dam  site; 
top  of  hill  S.  end  of 
dam ;  con*  from  hole  No. 
J>,  S4  feet  below  surface. 


Meojascopically :  (irey,  nearly  aphanitic,  with 

an  occasional  small  vesicle. 
Microscopically:    An  ordinary  olivine-basalt, 

rich  in  olivine. 


192 


NICARAGUA   CANAL  COMMISSION 


Number  i 

of        I 

8p<Bcimen.| 


Name. 


230 


Andesitic  tuif. 


235 


Basalt. 


242 


Basalt-amyg- 
daloid. 


249 


Augite- 

andesite. 


255 


Pyroxene- 

andesite. 


Locality. 


Core  from  hole  No.  180 ; 
in  channel  of  Rio  San 
Juan,  1  mile  below 
Machnca. 


Castillo;  core  from  hole 
No.  160,  head  of  Cas- 
tillo rapids ;  S.  side  of 
Rio  San  Juan ;  8  feet 
below  bed  of  river. 


Toro  rapids;  core  from 
hole  No.  143 ;  S.  side  of 
channel  of  Rio  San 
Juan ;  opposite  mouth 
of  Rio  Savalos  10  feet 
below  bed  of  river. 

Melchorita ;  core  from 
hole  No.  41 ;  in  the 
channel  of  the  Rio  San 
Juan  ;  2  feet  below  bed 
of  river. 


Rio  Grande  valley ;  core 
from  hole  No.  3 ;  Childs 
Route  Variant  II,  sta- 
tion 495 ;  35  feet  below 
surface. 


Description. 


Megascopically :    Apparently    a    rather    fine 

grey  tuff. 
Microscopically :  An  andesitic  tuff  containing 

fragments  of   limestone.       The    limestone 

shows  organic  remains. 

Megascopically :  Dark  grey  and  aphanitic. 
Microscopically :    Minute  phenocrysts  of  pla- 
gioclase  in   a  fine  groundmass  made  up   of 

J)lagioclase  microlites,  some  serpentinized 
erromagnesian  mineral,  iron  ore,  and  glass. 
The  rock  may  possibly  belong  with  the 
augite  andesites. 

Megascopically :  Weathered  brick-red  amyg- 
daloid. 

Microscopically:  Probably  an  amygdaloidal 
glassy  basalt,  but  original  character  is  ob- 
scured by  oxidation. 


Megascopically :  Dark  grey  with  small  pheno- 
crysts of  plagioclase  and  augite. 

Microscopically :  Porphyritic  structure.  Phe- 
nocrysts of  labradorite  (Abg  An^)  ]>  pale 
greenish  augite,  in  a^groundmass  of  plagio- 
clase, augite,  iron  ore  and  glass. 

Megascopically :  Nearly  black,  with  small 
phenocrysts  of  plagioclase  and  augite  in  a 
compact  groundmass. 

Microscopically :  Porphyritic  structure.  Phe- 
nocrysts of  labradorite  ]>  augite  ]>  rhombic 
pyroxene  (bronzite,  or  iron -poor  hypers- 
thene),  in  a  microlitic,  brown  glassy  base. 


NICARAGUA  CANAL  COMMISSION 


APPENDIX  a.  PLATE  VIII 


Sections    derived  Trom  borings   aTthe 

EASTERN     DIVIDE 

showing  classiricaTion  and  character 
of  matferisls. depths  ofrocK  decay, eTc 

EASTEBN   DIVIDE  EASTERN   DIVIDE         EASTERN    DIVIDE        EASTERN   DIVIDE 

M°  I  hi°S  NO  3  N°-4- 


Sta  1079 -lO 


1 


H 


STa.   lO^O-rS 


*" 


i 


DRILL  SECTIONS-EASTERN  DIVIDE. 


NICARAGUA  CANAL  COMMISSION 


APPENDIX  2,  PLATE  XII 


Sec^OKis  derived  from  boringa  aTthe 

UPPER   OCHOA    DAMSITE.    ■ 

showing  classification  and  charaCTer 

of  materia/s,  depHos  dfrocK  decoy,  etc 

UPPER  OCHOA  UPPER  OCMOA  UPPER   OCHOA  UPPER   OCHOA 

NO  3  NO  4  N°  a  N0  10 

iNofihbaniT.SaiiJuanniw  Ssutfibanx.^anJMnTiha    Sojfh  end i>mBrxsilB      Norftiena  oP  OamalTte 


8/;  ; 
'it: 


DRILL  SECTIONS-UPPER  OCHOA. 


NICARAGUA  CANAL  COMMISSION 


APPENDIX  2,  PLATE  XIH 


Sections  derived  from  boKingg  sttfie 
BOCA  SAN  CARLOS   DAMSITEl 

showing  classification  and  charcicTer 
ksT mSTerio\s,  depths  of  i-ocrt  decay,  eTc 
Boca  san  carlos      Boca  san  carlos     boca  3«n  carlos      boca  san  carlos 
N°  e  N°3  NO  197  NO  4 


inner  margin  oF  Otiter  margin   dP 

ftoodplsin   nOrtKof      floodp/mn  nor*iof 
nJoan  R.vor-  Son  Juan  Rivwr 


Foot  of  RosKJual 
aJopa  norrti  o^ 
SanJuoi  Ri*v«(- 


5-  '■:- 


Souffri  end  of  Darwsfffe 


DRILL  SECTIONS-BOCA  SAN  CARLOS. 


NICARAGUA  CANAL  COMMISSION 


APPENDIX  2.  PLATE  XIV 


SectiOKiQ  derived  froion  borings  aft  tine 
MACHUCA  DAMSITt.  SANTA  CRUZ  AND  CONCHUDA. 

showing  classifTcatiCi'i  and  character 
oTnoaterials,  deptVis  dT  roci<  decay,  estc  . 

SANTA  CRUZ  MACHUCA  MACHUCA    .  CONCHUDA 

NO  155  NO|  No-4  NOI92 


On  cut-ofT  abovo. 

Santa  Crux,  isoa**" 
from  5an  Juan  River 


■         - 

0  . 


i 


VaHoMf       aM       Mown 
•lav. 


>Ud  •■•»  wioMiad  wrth 
whita;  «an«a«  '••m  tn« 
«aaay  al  itelcaAia  raaks, 
VfafeaMit  IK  part  watar- 
i«M  luff  an«  aawBlem 
aiwta ,  aaniaiM  antaii 
fratmanla  af  fhnii 
«ra4aa  aawawafri   iiMa 


■4«a  oiay  HMMiatf  w«i| 
pinfe     an«     whiw.      «a- 


''"_'     tfewnwara    inia 


WhMa 
4an««4   aa 


tfwular    aiay ; 


1 


Nor^  &rtd  oF  Oamsihe. 


i   -  • 

0':- 


'.t; 


Is 


■■»■ 


1^- 

1% 


aiay, 


'  -     U»a      «aeay     af      «<••*■ 


aaniaMi««      iwah     «e>- 
•ania  tMff  a««   »]r*«ia> 


'.-,■ 

XL         ^  ^ ^ 

J[7>  muah     nrMa , 

h^-l    '  aama  ra«M«ai 


•    i  af     hafd     ivaii, 


^  - 


^^      Hairi   wifta  aalcai 


Sooth  end  dT  Oamsil'e 


ST 


I 


--'-, 


Ratf        etoy :        atiflHiy 


alalia    aa«*i«inin9    mucii 
•alaawic   matanai 


a:! 


^^ 


J'_ 


U«M  vaMaw  an« 
wima  saHtfy  aUy;  «a^ 
•<«a«  fram  uta  aaaay 
«f  santfalafia  eawtatiuin 
ivNicii  vataaAia  tuff  an4 
nrma. 


•aft        whiia        iMk ; 


aa<«taini«Hi  mwett 
0frA»;  aataraan  4-  M 
TDc-  antf  4'  4#  many  ra« 
...     ai««ai  aawWais  at   tfr4 

•;:^     an«      +  I&     emitfa      aa 
Mfttfaf       tua       aiamana 
7*    «nU   ta   chatky   alay. 


r: 


On  cut-off'  35o^frt3m 
San  Jusn  River 


Valaw  antf  «a4  aan^ 
alay ;  tfarivaa  fram 
Uia  daaay  of  Waicawta 
>a«ka,  ptahaaiy  salartaM 
Wft  an4  eenfiofnarata . 
•«a<aa  dawnwara   tnia 


^ 

B 

.»  . 

1^* 

-  — 

i  - 

• 

a 

« 

— i    "' 

•    . 

• 

9   ■-- 

r  a.  - 

Kwa  anri  afawn  aantfy 

m 

aiay  i   aaf ivc  a  aa  aoavai 

— 

baaamaa     fmnar    dawn- 

J..8afi  whWa  raak; 
.  ^'   aMy  waau>a*a«  taiaawia  I 
%  ',   aa«iMia«ia ;       «*aathai<a4  jl  Q 
*  J'  tuW  an«   aan(la«MMia.    " 


i 


DRILL  SECTIONS-MACHUCA,  SANTA  CRUZ  AND  CONCHUDA. 


5H( 


APPENDIX  2    PLATE  XV 


lo  a 


ISO 

too 


Ca 


APPENDIX  2    PLATE  XVI 


BOOO 


aooo 


i 


Sombrero  ff€ 
Cu9ro 


&ID| 


ma ni».ui,>iirjn.ffrf ■. t » f  u.i  [ij  i ,^ji  j^ 


o 

*^ 

c 


istmi 


I 


pi'  »'i* 


P^^^^^^Pp'i'^^f^^^y^^^^'^^P^^jf^^^^^^f^^'^T^^ 


-  .    .  .  .  j-.i  1- ^t' 


mm 

-  .j..  .^1 

•-.■s^-\ 

1  • 

^s 

APPENDIX  2    PLATE   XVU 
t'-^^:|-:--^  AHuviurri, Clay  iilt -and  Sand,' 
]   Residual  Cfay. 
Brito^and  Machucd.  fomtations. 

VolcarviCj  tuff  and  congtoinenste. 

Dacite. 

Baeatt  ^FK^  Artdeeite. 


4(3  iE3o  .        SO 


I*-'' 


■■■I#«*i 


^inmm 


f  h 


APPENDIX  III 


REPORT 


OF 


HYDROGRAPHIC  INVESTIGATIONS  IN  NICARAGUA 


MADE  FOR  THE 


NICARAGUA  CANAL  COMMISSION 


BY 


ARTHUR  P.  DAVIS 

Hydrographer 


13 


CONTENTS 


PAGE 


Stream  Measurements .'197 

Rio  Grande 198 

Brito  Station  on  Rio  Grande 198 

Tola  Station  on  Rio  Grande 198 

Lake  Nicaragua  201 

Station  at  Las  Lajas 202 

Rio  Viejo 203 

Rio  Xiieva 206 

Quebrada  Honda    207 

Station  at  Tipitapa 208 

San  L^baldo  and  Morrito 211 

Station  at  Fort  San  Carlos 211 

Rio  Frio 212 

Dry  Season  inflow  to  Lake  Nicaragua 213 

Rio  San  Juan 217 

Sabalos  Station  on  Rio  San  Juan 218 

Rio  Sabalos    222 

Castillo  Station 223 

Rio  San  Carlos 226 

Ochoa  Station  on  Rio  San  Juan : 232 

Rio  Machado    242 

Rio  Danta ; 243 

Rio  San  Francisco 243 

Rio  Limpio 248 

Upper  Station  on  Rio  Chanchos 250 

Lower  Station  on  Rio  Chanchos 251 

Nicholson  Creek 253 

Rio  Sarapiqui 254 

Rio  Taura 256 

Rio  Deseado 256 

Miscellaneous  Stream  Measurements 259 

Rainfall 262 

Daily  Rainfall  at  Stations  Maintained 264 

Miscellaneous  Rainfall  Records 278 


196  NICARAGUA  CANAL  COMMISSION 


Evaporation 


PAGE 

283 


GsNEBAL  Conclusions  Eeoarding  Water  Supply 291 

Discussion  of  Results 291 

Amount  of  Storage  Necessary 292 

Spillway  Capacity    294 

Value  of  the  Estimates 296 

Lake  Managua  as  a  Storage  Reservoir 298 

Sediment  Observations 299 

Temperature  and  Relative  HuMiDnY 304 


APPENDIX  III 


The  Hydrographic  and  Meteorologic  informa- 
tion required  by  the  Nicaragua  Canal  Commis- 
sion relates  to  three  principal  objects: 

1.  The  water  supply  for  the  use  and  leakage 
of  the  canal. 

2.  The  quantity  of  rainfall  and  volume  of 
streams,  considered  as  obstacles  to  construction. 

3.  The  volume  and  habit  of  excessive  floods, 
with  reference  to  their  permanent  control  and 
discharge  without  injury  to  the  canal  or  other 
property. 

The  desired  information  therefore  required 
an  investigation  of  the  discharge  of  all  streams 
of  importance  which  it  was  proposed  to  control 
during  construction  or  foB  which  it  was  neces- 
sary to  provide  diveraion  channels  or  spillways; 
and  measurements  of  rainfall  at  points  as  widely 
distributed  as  possible  throughout  the  basin  of 
Lake  Nicaragua. 

It  also  required  an  approximate  determination 
of  the  rate  of  evaporation  on  Lake  Nicaragua, 
and  some  investigation  of  the  sediment  carried 
l)v  the  larffer  rivers. 

STREAil  MEASUREMENTS. 

The  general  method  used  in  observing  the 
regimen  and  discharge  of  streams  is  substantially 
as  follows: 

A  point  is  selected  as  near  as  may  be  to  the 
location  at  which  knowledge  is  desired,  having 
reference  to  the  conditions  of  the  stream  itself, 
the  aim  being  to  secure  high  permanent  banks 


on  both  sides  of  the  river,  a  straight  channel  as 
uniform  in  depth  and  velocity  as  may  be,  and 
avoiding  any  location  which  is  a  short  distance 
above  an  important  tributary,  and  which  for  this 
reason  might  be  affected  in  the  matter  of  back 
water  by  floods  in  that  tributary.  A  gage  is 
placed  in  the  stream  near  one  bank,  graduated 
to  feet  and  tenths,  and  so  situated  if  possible 
as  to  be  read  convenientlv  from  the  shore.  It 
is  usually  possible  to  fasten  such  a  gage  in  deep 
water  to  the  trunk  of  an  overhanging  tree  and 
in  a  vertical  position.  The  height  of  ^ater  in- 
dicated by  this  gage  is  read  and  recorded  usually 
twice  every  day,  and  the  mean  of  the  two  read- 
ings taken  as  the  mean  gage  height  for  that  date. 
At  various  intervals,  depending  upon  the  facili- 
ties available  and  the  change  of  gage  height, 
measurements  of  discharge  are  made  with  a  cur- 
rent meter.  Soundings  are  taken  at  known  dis- 
tances from  an  assumed  initial  point  and  the 
velocity  measured  by  submerging  an  electric 
current  meter  at  six-tenths  of  the  measured 
depth,  and  holding  it  in  that  position  for  a 
length  of  time  sufiicient  to  make  a  good  deter- 
mination of  the  velocity  at  that  point,  usually 
100  seconds  or  more.  This  operation  is  repeated 
at  short  intervals  for  the  entire  width  of  the 
stream,  and  from  these  observations  the  discharge 
in  cubic  feet  per  second  is  computed  for  each 
section  by  multiplpng  the  depth,  width  and 
measured  velocity  together.  The  discharge  of 
the  several  sections  being  added  together  form  a 


198 


NICARAGUA  CANAL  COMMISSION 


result  for  the  discliarge  of  the  entire  stream.  At 
the  beginning  and  end  of  the  gaging  a  careful 
note  is  made  of  the  stage  of  the  water  indicated 
on  the  river  gage,  and  the  mean  of  those  two 
observations  is  taken  as  the  mean  gage  height 
at  the  time  of  observation.  It  is  the  effort  to 
have  such  observations  well  distributed  with 
reference  to  the  height  of  water  in  the  river,  in 
order  to  show  the  relation  of  the  indications  of 
the  gage  rod  to  the  actual  discharge  of  the 
stream.  This  relation  is  found  to  be  reasonably 
definite  and  uniform  for  most  of  the  streams, 
and  by  plotting  the  gage  heights  as  ordinates 
and  the  discharge  results  as  abscissas  their  gen- 
eral relation  is  established  and  a  curve  drawn, 
satisfying  as  nearly  as  possible  all  the  observa- 
tions made. 

Bbito  Station  on  Eio  Grande. 

This  "station  was  established  by  D.  H.  Bald- 
win on  January  8,  about  1  mile  below  La  Flor 
dam  site  on  Rio  Grande,  just  below  where  the 
stream  bends  to  the  north. 

A  cable  and  gaging  car  were  put  in  place  for 
taking  measurements.  The  gage  was  driven 
in  the  bed  of  the  river  near  the  left  bank,  and 


the  top  fastened  to  the  tagged  wire.  As  this 
was  deemed  insecure,  a  new  gage  was  put  in 
place  on  January  22  about  two  hundred  feet 
farther  upstream,  which  was  driven  into  the 
clay  bottom,  and  spiked  to  a  tree  growing  on  the 
bank.  When  the  old  gage  read  1.85  the  new 
gage  read  3.38.  The  readings  are  here  re- 
duced to  the  datum  of  the  new  gage. 

The  channel  begins  to  curve  a  short  distance 
above  the  station.  The  left  bank  is  high  and 
steep.  The  right  may  sometimes  overflow  at 
high  water.  Later  operations  by  the  surveying 
parties  having  shown  the  desirability  of  measure- 
ments of  Rio  Tola,  the  Rio  Grande  station  was 
removed  June  13,  to  a  point  below  the  mouth 
of  Rio  Tola,  in  order  that  both  streams  could 
be  observed  from  one  camp.  It  is  about  300 
yards  below  the  junction  of  the  Tola  and  Rio 
Grande.  The  gage  is  a  vertical  rod  divided  to 
feet  and  tenths,  and  fastened  to  an  overhanging 
tree  on  the  left  bank  of  the  river.  Xear  this 
point  the  cable  is  stretched  across  the  river, 
upon  which  runs  a  gaging  car  from  which 
measurements  are  made,  a  tagged  wire  being 
stretclied  alongside. 


LIST  OF  DISCHARGE  MEASUREMENTS  MADE  ON  RIO  GRANDE  BELOW  MOUTH 

OP  THE  TOLA. 


Date. 

Hydrographer. 

Meter 

niirnltPi* 

Gaffe 
heiffht 

Area  of 
section 

Mean  ve- 
locity (feet 

Discharge 
(second- 

Remarks. 

(feet). 

(sq.  feet). 

per  sec.). 

feet). 

Jan.     9 D. 

H.  Baldwin. . . . 

•  •  •  • 

3.48 

59 

1.36 

80 

"     22 A. 

P.  Davis 

94 

8.44 

56 

1.11 

62 

June    4 

it 

•   ••••■ 

94 

2.95 

26 

0.68 

18 

July    2 D. 

H.  Baldwin 

1984 

8.18 

68 

2.35 

161 

New  gage-rod  reads,  .85^  less. 

♦♦     30 

1984 

6.80 

815 

4.15 

1,306 

Aug.  10 

1984 

2.40 

70 

0.92 

65 

"     21.... 

1984 

4.30 

164 

2.93 

481 

Sep.   14 

1984 

8.78 

124 

2.73 

339 

'*     21 

Float. 

11.10 

606 

4.55 

2,758 

*'     29.... 

1984 

4.00 

144 

2.94 

428 

Oct.      8 H. 

C.  Hurd 

Float. 

3.60 

122 

2.38 

.285 

"       9 

•   ••••• 

i( 

5.92 

275 

3.98 

1,092 

»*     10.... 

•   •■••• 

i> 

5.00 

218 

3.88 

718 

-     15.... 

•   ••■•• 

(i 

8.80 

474 

4.28 

2,026 

'»     27 

•   ■•••• 

Meter  B.  & 
B.  No.  1. 

4.25 

163 

4.12 

675 

Velocity  taken  at  .5  depth. 

Nov.  28 

•   ••••• 

1 

8.82 

88 

2.88 

249 

ii            ti            it 

Dec.  13 

•   ••••• 

1 

2.99 

69 

2.50 

172 

ti            ii            ii 

APPENDIX   III.— HYDROGRAPHIC   REPORT 


199 


RATING  TABLE  FOR  RIO  GRANDE  BELOW  MOUTH  OF  THE  TOLA. 
This  table  is  applicable  only  from  January  6,  1898,  to  June  13,  1898. 


Gai 


height.     I>i«^»>*'-go. 


Gage 
height 


Discharge. 


h?lX     "'""argo. 


helX.    D'oohargc. 


Gage 
height. 


Discharge. 


Feet. 

Second-feet. 

Feet, 

Second-feet. 

Feet. 

Second-feet. 

Feet. 

Second-feet. 

Feet. 

Second-feet. 

2.7 

9 

3.1 

85 

3.5 

75 

3.9 

115 

4.3 

155 

2.8 

12 

3.2 

45 

3.6 

85 

4.0 

125 

•   •   • 

•   •   • 

2.9 

17 

3.:^ 

55 

8.7 

95 

4.1 

135 

•    •   • 

•   •   • 

8.0 

25 

8.4 

05 

3.8 

105 

4.2 

145 

•   •  ■ 

■   •   ■ 

RATING  TABLE  FOR  RIO  GRANDE  BELOW  MOUTH  OF  THE  TOLA. 
This  table  is  applicable  only  from  June  13,  1898,  to  December  31,  1898. 


Gage 
height. 

Discharge. 

Gage 
height. 

Discharge. 

Gage 
height. 

Discharge. 

Gage 
height. 

Discharge. 

Gage 
height. 

Discharge. 

Feot. 

Second -ft. 

Feet. 

Second-ft. 

Feet. 

Second-ft. 

Feet. 

Second-ft. 

Feet. 

Second-ft. 

1.6 

12 

3.6 

261 

5.6 

892 

7.6 

1,575 

9.6 

2,275 

1.7 

13 

3.7 

287 

5.7 

926 

7.7 

1,610 

9.7 

2,310 

1.8 

14 

3.8 

314 

5.8 

960 

7.8 

1,.645 

9.8 

2,345 

1.9 

16 

3.9 

342 

5.9 

994 

7.9 

1,680 

9.9 

2,380 

2.0 

20 

4.0 

371 

6.0 

1,028 

8.0 

1,715 

10.0 

2,415 

2.1 

27 

4.1 

401 

6.1 

1,062 

8.1 

1,750 

10.1 

2,450 

2.2 

35 

4.2 

432 

6.2 

1,096 

8.2 

1,785 

10.2 

2,485 

2.8 

44 

4.3 

464 

6.3 

1,130 

8.3 

1,820 

10.3 

2.520 

2.4 

54 

4.4 

496 

6.4 

1,164 

8.4 

1,855 

10.4 

2,555 

2.5 

65 

4.5 

528 

6.5 

1,198 

8.5 

1,890 

10.5 

2,590 

2.6 

77 

4.6 

560 

6.6 

1,232 

8.6 

1,925 

10.6 

2,625 

2.7 

90 

4.7 

592 

6.7 

1,266 

8.7 

1,960 

10.7 

2,660 

2.8 

104 

4.8 

625 

6.8 

1,300 

8.8 

1,995 

10.8 

2,695 

2.9 

119 

4.9 

658 

6.9 

1,334 

8.9 

2,030 

10.9 

2,730 

3.0 

135 

5.0 

691 

7.0 

1,368 

9.0 

2,065 

11.0 

2,765 

8.1 

152 

5.1 

724 

7.1 

1,402 

9.1 

2,100 

11.1 

2,800 

3.2 

170 

5.2 

757 

7.2 

1,436 

9.2 

2,135 

11.2 

2,835 

8.3 

190 

5.3 

790 

7.3 

1,470 

9.3 

2,170 

11.3 

2,870 

8.4 

212 

6.4 

824 

7.4 

1,505 

9.4 

2,205 

11.4 

2,905 

8.5 

236 

5.5 

858 

7.5 

1,540 

9.5 

2;240 

•   •   •   • 

•   •  •   • 

ESTIMATED  MONTHLY  DISCHARGE  OF  RIO  GRANDE  BELOW  MOUTH  OF  THE  TOLA. 


Discharge  in  Second-Feet.  Total  in 

Month.                 / • V  A /.«£»_  ij'*w»4. 

Maximum!.    Minimum.    Moan.  Acre-i-oet. 

189H. 

January  (6-31)  ...       75               60               69  3,340 

February- 55              41              49  2,720 

March 40               25               35  2,150 

April    35               17               25  1,490 

May   85               17               28  1,720 

June 1,990              17            110  6,550 

17,970 


M.«th  Discharge  in  Second-Feet.         ^otal  in 

Maximum.    Minimum.    Mean.    Acre-ueei 

1898 

Brought  forward,  17,970 

July 2,030  55  121  7,440 

August 145  45  67  4,120 

September 2,975  55  ;J53  15,050 

October 2,065  260  596  36,650 

November 1,028  190  282  16,780 

December 190  97  130  7,990 

Total 106,000 


200 


NICARAGUA  CANAL  C0UUI8SI0M 


"3w 

r 

sss; 

Tfsr 

"J 

X 

(SS 

X, 

MPT. 
ION 

OCT.    1   NOV. 
1    »  1  .0  M 

s%\ 

1 

; 

< 

1 

1 

hi 

L 

, 

I 

■ 

-. 

1. 

- 

1 

1 

I 

t 

M 

i 

A 

I 

1 

1 

1 

1 

1 

Fia.  1.    Diagram  of  Dally  Dlecbarga  of  Rio  Qruide,  1898. 
LIST  OP  HBASUREMBNTS  HADG  ON  RIO  TOLA.  \  MILE  ABOVE  ITS  MOUTH. 


No. 

^-  Hydrognipher. 

Meter 
number. 

s 

B.? 

'sTS 

■!»-•       ».o,„.. 

Julj     a....D.  H.  Baldwin... 

19S4 

3.31 

48.1 

1.41 

68 

Ang  10... 

" 

1984 

1.60 

39.4 

0.96 

38 

■'       31... 

1«84 

3 

80 

38.1 

3.19 

61 

"       39... 

1984 

35 

98.0 

3.83 

379 

Sept.  H... 

1984 

03 

36.8 

2.80 

103     New  Rod. 

"     ai... 

Ftoite 

i» 

360.8 

2.B7 

TT4 

Oct.      8. . . 

H.  C.  Hnrd 

S5 

53.7 

3.35 

133 

U. .. 

es 

B5 

69.0 
183.7 

3.71 

187 

408 

10 

■'        17... 

3.5 

iOS.1 

2.86 

800 

11 

Not.  33... 

B.  &  B.  1 

14 

39.0 

4.31 

163     Velocity  taken  at  0. 

deptb. 

13 

"       37... 

I 

]S 

36.5 

S.73 

136 

18 

Dec.    18... 

1 

75 

36.3 

3.30 

114            

APPENDIX   III.— HYDROGRAPHIC   REPORT 


201 


RATING  TABLE  FOR  RIO  TOLA  %  MILE  ABOVE  ITS  MOUTH. 
This  table  is  applicable  only  from  September  1,  1898,  to  November  1,  1898. 


Gai 


Gage 


heiX     D'Bcharge.  hegfft.     Discharge 


hel^t.      Dtacharge. 


hel^t.     D"»o»""KO-  biliSt.     Discharge. 


Feet. 

Second-ft. 

Feet. 

Second-ft. 

Feet. 

Second-ft, 

Feet. 

Second-ft. 

Feet. 

Second-ft. 

2.0 

18 

3.1 

91 

4.2 

252 

5.3 

428 

6.4 

608 

2.1 

20 

3.2 

103 

4.3 

268 

5.4 

444 

6.5 

625 

2.2 

24 

3.3 

116 

4.4 

284 

5.5 

460 

6.6 

642 

2.3 

29 

3-4 

130 

4.5 

300 

5.6 

476 

6.7 

659 

2.4 

34 

3.5 

145 

4.6 

316 

5.7 

492 

6.8 

«76 

2.5 

40 

3.6 

160 

4.7 

332 

5.8 

508 

6.9 

698 

2.6 

46 

3.7 

175 

4.8 

348 

5.9 

524 

7.0 

710 

2.7 

53 

3.8 

190 

4.9 

864 

6.0 

540 

7.1 

728 

2.8 

61 

3.9 

205 

5.0 

380 

6.1 

557 

7.2 

746 

2.9 

70 

4.0 

220 

5.1 

396 

6.2 

574 

7.8 

764 

3.0 

80 

4.1 

236 

5.2 

412 

6.3 

591 

.  • . 

•   •   • 

RATING  TABLE  FOR  RIO  TOLA  %  MILE  ABOVE  ITS  MOUTH. 
This  table  is  applicable  only  from  November  1,  1898,  to  December  31,  1898. 


Gage 
height. 

Discharge. 

hei^t. 

Discharge. 

Gage 
height. 

Discharge. 

Gage 
height. 

Discharge. 

Feet. 

Second-ft. 

Feet. 

Second-ft. 

Feet. 

Second-ft. 

Feet. 

Second-ft^ 

2.6 

65 

3.0 

108 

3.4 

168 

3.8 

228 

2.7 

78 

3.1 

123 

3.5 

183 

3.9 

244 

2.8 

83 

3.2 

138 

3.6 

198 

4.0 

260 

2.9 

95 

3.3 

153 

3.7 

213 

4.1 

276 

ESTIMATED  MONTHLY  DISCHARGE  OF  RIO  TOLA  %  MILE  ABOVE  ITS  MOUTH. 


Month. 
1808. 


Discharge  in  Second-Feet.         Total  in 


Maximum.    Minimum.    Mean.  Acre-Feet. 


Month. 
1898. 


Discharge  in  Second- Feet.         Total  in 
Maximum.    Minimum.    Mean!  Acre-Feet. 


June  (9-30) 355 

July 163 

August 57 

September 364 


12 
21 
20 
39 


53 

46 

30 

113 


2,310 
2,830 
1,840 
6,660 

13,640 


October 452 

November 270 

December 100 

Total 


Brought  forward,  13,640 
130  246  15,125 

100  160  9,520 

65  79  4,860 


43,145 


Lake  Xicaraoua. 

Lake  Nicaragua  has  an  area  of  2975  square 
miles.  Its  greatest  length  is  from  north-north- 
west, to  south-southeast,  and  is  about  100  miles. 
Its  extreme  width  is  about  45  miles. 

West  of  the  center  is  an  island  occupied  by 
the  volcanoes  Ometepe  and  iladera,  which  stand 
about  5000  feet  above  the  lake  level,  adding 
greatly  to  the  scenic  beauty. 


Madera  is  the  most  southern  of  a  line  of  vol- 
canoes of  comparatively  recent  origin,  which 
extends  in  a  northwesterly  direction  nearly  to 
the  bay  of  Fonseca,  including  Ometepe,  Zapa- 
tero,  Mombacho,  Chiltepe,  Momotombo,  and 
manv  others. 

The  prevailing  easterly  trade  winds  cause  a 
moderately- heavy  surf  to  beat  almost  constantly 
on  the  western  shore,  causing  the  formation  of 


202 


NICARAGUA  CANAL  COMMISSION 


a  decided  beach  on  tliat  side,  while  on  the  east- 
em  shore  aquatic  vegetation  grows  far  out  into 
the  water.  This  shore  is  flat  and  muddy,  with 
no  well-marked  beach. 

Except  in  the  southeastern  portion  the  lake  is 
deep,  reaching  in  one  point  near  the  southern 
foot  of  Madera  to  a  depth  of  200  feet. 

Lake  Nicaragua  receives  the  waters  of  a  large 
number  of  tributaries,  the  most  important  being 
Rio  Frio  and  Rio  Pisote  on  the  southern  end, 
which  rise  in  the  high  mountains  of  Costa 
Rica  and  maintain  their  flow  throughout  the 
dry  season,  and  Malacatolla  and  Tipitapa  on  the 
northern  end.  The  latter  brings  the  waters  of 
Lake  Managua,  which  lies  to  the  northwest  of 
Lake  Nicaragua  and  has  an  area  of  al)out  500 
square  miles.  The  drainage  area  as  estimated 
from  the  best  information  obtainable,  is  as  fol- 
lows: 

Sq.  miles. 

Area  of  land  surface  draining  directly 

to  Lake  Nicaragua   6,640 

Area  of  Lake  Nicaragua 2,975 

Lake  Managua  and  tributary  basin. . . .  3,035 

Total 12,450 

The  control  of  the  waters  of  Lake  Nicaragua 
is  vital  to  the  practical  operation  of  the  proposed 
ship  canal  and  has  an  important  bearing  upon 
the  cost  and  the  plans  of  any  project  proposed. 
Careful  observations  of  its  fluctuations,  of  the 
maximum  and  minimum  inflow  and  outflow,  and 
of  evaporation  from  its  surface  are  therefore 
-very  important. 

Las  Lajas. 

A  station  was  established  on  the  margin  of 
Lake  Nicaragua,  about  seven  miles  southeast 
of  Rivas,  and  about  3500  feet  north  of  the 
mouth  of  Las  Lajas,  on  January  19.  The  gage 
was  placed  in  a  long  box  with  open  ends  and 
seams,  which  was  fastened  to  the  sunken  wreck 


of  a  large  boiler  of  one  of  the  Vanderbilt 
steamers,  as  shown  in  the  figure.  The  box  and 
the  boiler  served  to  protect  the  gage  from  the 
violence  of  the  breakers  prevalent  on  this  coast, 
but  afforded  entirely  free  access  to  the  water. 
The  gage  as  first  placed  was  insecurely  fastened, 
and  during  a  storm  the  waves  beat  it  down.  It 
was  replaced  on  February  7  by  Mr.  J.  A.  Bull 
in  the  position  which  it  now  occupies.  The 
gage  is  inclined  to  the  vertical  to  such  an  ex- 
tent that  one  foot  vertical  corresponds  to  1.014 
foot  on  the  rod.  The  10-foot  mark  is  .65  feet 
below  bench  mark  No.  1,  which  is  the  highest 
point  of  a  large  cylinder  nearly  buried  in  the 
sand  on  shore.  The  10-foot  mark  is  108.04 
feet  above  sea  level  by  the  levels  of  the  Nica- 
ragua Canal  Commission. 

The  ebb  and  flow  of  the  waves  kept  the  water 
level  constantly  changing  on  the  rod,  and  the 
readings  were  taken  by  averaging  high  and  low 
readings  occurring  within  a  few  seconds.  Most 
of  the  time  the  eastern  trades  blew  constantly, 
with  considerable  force,  but  during  May  were 
many  calm  days,  and  some  adverse  winds. 

During  April  the  declining  lake  surface 
threatened  to  leave  the  gage  on  dry  land,  and 
another  gage  was  placed  in  deeper  water,  about 
200  feet  north  of  the  first  one.  This  was  placed 
vertical  and  fastened  to  another  portion  of  the 
wreck.  On  this  gage  the  9-foot  mark  is  103.19 
feet  above  sea  level.  It  was  observed  from  May 
1  to  July  1 6,  when  the  surf  became  too  deep  for 
the  observer  to  safely  read  it,  and  observations 
were  transferred  to  gage  No.  1. 

Temperature,  humidity  and  wind  observations 
were  taken  at  this  station,  and  at  the  mouth  of 
Las  Lajas  an  evaporation  pan  and  rain  gage  were 
maintained  and  observed. 

The  elevation  of  Lake  Nicaragua  is  given 
under  the  head  of  Fort  San  Carlos,  page  211. 


APPENDIX   III.— HYDHOORAPHIC   REPORT 


203 


Kio  ViEJO, 
This  station  is  abotit  500  yards  above  the  ford 
known  as  Paso  Real  on  the  Rio  Viejo  where 
the  Matagalpa-Leon  road  crosses  the  Rio  Viejo. 
A  gage  was  placed  at  this  point  on  February  1, 
wliich  consisted  of  a  vertical  unpainted  cedar 
stick,  marked  with  nails  and  notches  to  feet  and 
tenths,  nailed  to  a  tree  on  the  right  bank.  A 
bench  mark  was  established  on  tho  right  bank 


consisting  of  a  wire  nail  driven  in  the  highest 
point  of  a  stump  66  feet  west  of  the  gage.  It 
is  46.2  feet  above  zero  of  gage,  A  cable  was 
stretched  across  the  river  a  short  distance  above 
the  gage  from  which  measurements  of  floods 
were  made  by  means  of  a  gaging  car  of  the 
usual  pattern.  Measurements  at  low  water 
were  made  by  wading. 


■ 


m 


Fio.  2.  Diagram  of  Dally  Dlscharse  ot  Rfo  Vlelo,  189S. 
DAILY  GAGE  HEIGHT  OF  RIO  VIEJO  AT  PASO  REAL  FOR  1898. 


Har.         April.         Mar.         June.  July.         Aug.         Sept. 


Oct,  Nov. 


l.WS 

.84 

.71 

3.75 

7.01           S 

57 

4.30 

5.30 

3.96 

3.75 

3,41 

3.B7 

I.B7 

.71 

3.35 

6.86           ! 

45 

8.05 

4.65 

3.85 

3.74 

3.40 

3.84 

i.es 

.71 

3  95 

5.97           3 

54 

3.78 

5.85 

3.73 

3,73 

3,41 

3.83 

L99 

.71 

3.75 

■5.4S           ! 

41 

4.35 

4.49 

S.S5 

3.71 

3.43 

3.30 

1.00 

.81 

.71 

3.61 

5.17            3 

H] 

9.00 

4.31 

8.61 

3.70 

3.45 

3.38 

1.B8 

.81 

.71 

3.S5 

4.91 

5.85 

4.03 

.'i.53 

3.68 

3.97 

2.25 

3.18 

.80 

.70 

3.74 

5.13 

.%.10 

3.88 

8.41 

3.75 

a.84 

3.30 

2.13 

.80 

.70 

4.0:1 

5.68 

4.50 

3.97 

3.88 

3.78 

3.79 

3.19 

3.09 

.70 

4.45 

4.95 

3,38 

3.95 

2.69 

10 

3.18 

3.00 

.70 

4.01 

4.84 

8,95 

3.94 

3.63 

11 

3.17 

3.0.5 

.78 

.70 

4.44 

30 

8.94 

S.19 

3.89 

3.59 

13 

3.1S 

.77 

.70 

3.56 

8.69 

6.40 

3.30 

3,78 

8.56 

13 

3.U 

.76 

.70 

S.15 

6.70 

«,:!3 

3,43 

3  74 

3.53 

204 


NICARAGUA  CANAL  COMMISSION 


DAILY  GAGE  HEIGHT  OF  RIO  VIEJO  AT  PASO  REAL  FOR  1898.— Continued. 


Day 

Feb. 
1808. 

Mar. 

April. 

May. 

Juno. 

July. 

Aug. 
3,30 

Sept 
14.50 

6.  .30 

Nov. 
3.  ,59 

Dec.            .Tan. 
IHW. 

14 

2.18 

1.98 

L74 

1.70 

2.98 

6.84 

8.71            3.  .50 

15 

2.11 

1.97 

1.74 

1.70 

2.75 

5.90 

3.80 

17.  .50 

6.37 

3.37 

3.69            2.49 

16 

f  •  •  • 

1.95 

L74 

1.70 

2.65 

5.85 

•  •  •  • 

9.50 

.5.31 

.3.13 

2.66            2.49 

17 

•  •  •  - 

1.98 

1.74 

1.70 

2.62 

4.77 

.... 

7.75 

6.45 

.3.07 

2.63            2.48 

18    • 

2.08 

1.93 

1.78 

1.79 

8.11 

4.46 

.... 

6.35 

9.00 

.3.00 

2.00            2.48 

19 

2.08 

1.92 

1.78 

1.84 

9.90 

4.17 

-  •  •  • 

6.  ,53 

7.33 

'        ,3.00 

2.  .59            2.45 

20 

2.06 

1.9S 

1.'.'2 

1.80 

30.70 

3.97 

.... 

6.80 

10.89 

3.98 

2.  .58            2.44 

21 

2.02 

1.91 

1.78 

1.96 

12.50 

3.83 

.... 

6.60 

8.44 

3.95 

2.  .56            2.43 

23 

2.01 

1.00 

1.72 

2.81 

10.34 

3.70 

.... 

5.95 

9.07 

3.95 

3.  ,50            2.35 

28 

2.05 

1.88 

1.72 

6.55 

8.63 

8.65 

.... 

5  81 

7.04 

2.91 

•»•  "W                           .... 

24 

2.02 

1.87 

1.72 

6.60 

13.85 

8.65 

5.60 

,5.20 

5.90 

2.90 

2..56            

25 

2.01 

1.85 

1.72 

11.94 

9.90 

3.43 

4.  .38 

4.75 

.5.43 

3.87 

*tm  »tt                                  .... 

26 

•  •       ■ 

1.88 

1.71 

6.78 

7.35 

3.38 

3.93 

5.10 

5.70 

3.84 

3.51 

27 

•    car 

1.87 

1.71 

5.71 

6.40 

3.38 

3.76 

7.85 

5.37 

3.84 

3.48 

28 

•    •    •    • 

1.85 

1.71 

5.15 

27.00 

8.50 

3.65 

6.25 

4.90 

3.83 

3.48 

29 

•     •    •    • 

1.83 

1.71 

.5.59 

11.41 

3.78 

9.33 

.5.31 

4.75 

3.84 

O   AK 

•w.t.y               .... 

30 

•     •     •    • 

1.85 

1.71 

4.31 

8.03 

3.71 

.5.55 

6.08 

4.43 

3.80 

o  44 

81 

•     •    •    • 

1.83 

■   •   •   • 

4.14 

•   •   •  • 

3.62 

3.90 

•    •   ■   • 

4.16 

•    ■   •   ■ 

3.43           

LIST  OF  DISCHARGE  MEASUREMENTS  MADE  ON  RIO  VIEJO  AT 

PASO  REAL. 

Date. 

Hydrotirrapher. 

Meter 
number. 

GaKe 
beiflrht 
(feet). 

Area  of 

sootion 

(square  feet). 

Mean  velocity 

(feet 

|)er  second). 

DiM;hargo 
l8econd- 

l<HJt). 

Feb.     8. 

.F.  C.  G 

reen 

7 
7 

2.20 
2.08 

17.7 
14.1 

1.60 
1.40 

3S  3 

»»    18. 

30.7 

*«    28. 

iC 

ct 

tl 

(t 

G.  p.  PI 

7 
7 
7 
7 
7 
7 

1.99 
2.12 
1.94 
1.85 
1.79 
1.72 

12.8 
14.0 
11.4 
10.8 
9.6 
6.2 

1.30 
1..57 
1.33 
0.55 
0.44 
0.61 

1,5.3 

Mar.    8. 

33.0 

*«    18. 

14.0 

••  .  28. 

6.0 

April   8. 
•»    20. 

4.3 

tilllp...    . 

•••••• 

3.8 

"    28. 

(I 

7 

7 

1.71 
1.71 

5.4 
7.3 

0.,58 
0.37 

3.3 

May     6. 

3.5 

"    14. 

It 
t( 

4( 
(i 
t4 
It 
it 
il 
i( 

7 

7 
7 
7 
7 
7 
7 
7 
7 

1.70 

3.13 

12.  .53 

3.65 

3.63 

2.78 

11.63 

13.34 

4.95 

6.8 

63.4 
964.0 

74 

68 

33 
895 
976 
1.57 

0.33 
3.30 
5.06 
4.39 
4.04 
3.  .54 
4.85 
4.C5 
3.91 

2.2 

»*    22. 

306 

"    25. 

4874 

Jnne     1 . 

317 

<>      8 

374 

•*     15. 

114 

»'     23. 

4.344 

♦'    29. 

4539 

July     6. 
»♦    13. 

4.56 

it 
tt 
tt 
tt 
tl 
It 

..Fred.  D 
it 

It 

7 
7 
7 

7 

■» 
i 

1 

7 
7 
7 

6.  ,50 
3.97 
3.38 
3.59 
5.73 
8.33 
5.03 
.'i.OO 
9.90 

315 

83 

55 

66 

188 

460 

144 

184 

674 

3.08 
3.21 
3.78 
3.93 
4.40 
4.53 
3.36 
4.41 
4.89 

1073 

*'    20. 

266 

»'    37. 

153 

AuL^.    3. 

193 

Sep.    19 

H2S 

♦*    37. 

2,074 

Oct.      3. 

avis 

469 

''    10. 

813 

'*     18 

3,300 

— « 

NICARAGUA  CANAL  COMMISSION 


APPENDIX  3,  PLATE  I 


APPENDIX   III.— HYDROGRAPHIC   REPORT 


205 


LIST  OF  DISCHARGE  MEASUREMENTS  MADE  ON  RIO  VIEJO  AT  PASO  REAL.— Continued. 


Date. 
1806. 

Hydrographer.                ^^^^^ 

■ 

Gage 

height 

(feet). 

Area  of              Mean  velocity 
section                     (feet 
(square  feet).          per  second). 

Discharge 
(second- 
feet). 

Oct.   25. 

Fred. 

Davis  . . . 

7 
7 
7 

7 
7 
7 
7 
7 
7 
7 
7 

5.41 
4.00 
3.42 
3.52 
2.95 
2.82 
2.70 
2.94 
2.68 
2.56 
2.45 

216 
81 
54 
72 
34 
85 
27.5 
45 
33.5 
28.5 
25 

4.11 
3.48 
3.42 
2.16 
2.73 
2.36 
2.74 
1.95 
1.76 
1.71 
1.59 

886 

Nov.     1. 

i 

282 

"      7. 

182 

»'     14 » 

228 

"    21 

* 

94 

"    28. 

82 

Dec.     5. 

i 

i 

75 

»«    10. 

88 

t*      15.. 4 

59 

*»    22 * 

49 

**    29. * 

39 

1899. 

Jan.     8 

* 

7 
7 
7 

2.40 
2.68 
2.49 

25.6 
34.7 
25.7 

1.28 
1.77 
1.74 

81.5 

u      9 

61.3 

"     15. 

44.9 

RATING  TABLE  FOR  RIO  VIEJO  AT  CROSSING  OF  MATAGALPA-LEON  ROAD. 

This  table  is  applicable  only  from  May  21,  1898,  to  December  1, 

1898. 

Gage 
height. 

Discharge. 

Gage 
height. 

Discharge. 

Gage 
height. 

Discharge. 

Gage 
height. 

Discharge. 

Gage 
height. 

Discharge. 

Feet.     Seoond-feet. 

Feet. 

Second-feet. 

Feet. 

Second-feet. 

Feet 

Becond-feet. 

Feet. 

Second-feet. 

1.5 

0 

4.6 

884 

7.7 

1,760 

10.8 

3,765 

13.9 

5,780 

1.6 

1 

4.7 

406 

7.8 

1,820 

10.9 

3,830 

14.0 

5,845 

1.7 

3 

4.8 

4?8 

7.9 

1,880 

11.0 

3,895 

14.1 

5,910 

1.8 

6 

4.9 

452 

8.0 

1,945 

11.1 

8,960 

14.2 

5,975 

1.9 

10 

5.0 

475 

8.1 

2,010 

11.2 

4,025 

14.3 

6,040 

2.0 

15 

5.1 

500 

8.2 

2,075 

11.3 

4,090 

14.4 

6,105 

2.1 

21 

5.2 

525 

8.3 

2,140 

11.4 

4,155 

14.5 

6,170 

2.2 

28 

5.3 

555 

8.4 

2,205 

11.5 

4,220 

14.6 

6,285 

2.3 

36 

5.4 

585 

8.5 

2,270 

11.6 

4,285 

14.7 

6,300 

?.4 

44 

5.5 

620 

8.6 

2,335 

11.7 

4,350 

14.8 

6,365 

2.5 

52 

5.6 

655 

8.7 

2,400 

11.8 

4,415 

14.9 

6,480 

2.6 

60 

5.7 

695 

8.8 

2,465 

11.9 

4,480 

15.0 

6,495 

2.7 

68 

5.8 

735 

8.9 

2,530 

12.0 

4,545 

15.1 

6,510 

2.8 

77 

5.9 

780 

9.0 

2,595 

12.1 

4,610 

15.2 

6,625 

2.9 

86 

6.0 

830 

9.1 

2,660 

12.3 

4,675 

15.3 

6,690 

3.0 

98 

6.1 

880 

9.2 

2,725 

12.3 

4,740 

15.4 

6,755 

3.1 

112 

6.2 

930 

9.3 

2,790 

12.4 

4,805 

15.5 

6,820 

3.2 

126 

6.3 

980 

9.4 

2,855 

12.5 

4,870 

15.6 

6,885 

3.3 

140 

6.4 

1,030 

9.5 

2,920 

12.6 

4,935 

15.7 

6,950 

3.4 

156 

6.5 

1,080 

9.6 

2,985 

12.7 

5,000 

15.8 

7,015 

3.5 

172 

6.6 

1,130 

9.7 

3,050 

12.8 

5,065 

15.9 

7,080 

3.6 

188 

6.7 

1,180 

9.8 

3,115 

12.9 

5,130 

16.0 

7,145 

3.7 

206 

6.8 

1,235 

9.9 

8,180 

13.0 

5,195 

16.1 

7,210 

3.8 

224 

6.9 

1,290 

10.0 

8,245 

13.1 

5,260 

16.2 

7,275 

3.9 

242 

7.0 

1,345 

10.1 

3,310 

13.2 

5,325 

16.3 

7,340 

4.0 

262 

7.1 

1,400 

10.2 

8,875 

13.8 

5,390 

16.4 

7,405 

4.1 

282 

7.2 

1,460 

10.8 

3,440 

13.4 

5,455 

16.5 

7,470 

4.2 

302 

7.3 

1,520 

10.4 

3,505 

13.5 

5,520 

16.6 

7,585 

4.3 

322 

7.4 

1,580 

10.5 

3,570 

13.6 

5,585 

16.7 

7,600 

4.4 

342 

7.5 

1,640 

10.6 

3,635 

13.7 

5,650 

16.8 

7,665 

4.5 

363 

7.6 

1,700 

10.7 

3,700 

13.8 

5,715 

- 

16.9 

7,730 

206 


NICARAGUA  CANAL  COMMISSION 


RATING  TABLE  FOR  RIO  VIEJO  AT  CROSSING  OF  MATAGALPA-LEON  ROAD. 
This  table  is  applicable  only  from  December  1,  1898,  to  January  22,  1899. 


heSht.      I>i8charge. 


Feet.  Second-feet. 
1.9  10 

2.0  15 

2.1  20 


heiX.     ^'^^^^^''  heS't.      I>»»^han?f.  ^J^^     Discharge. 


Feet.  Second-feet. 
2.2  26 

2.8  32 

2.4  38 


Feet.  Second  -  feet. 

2.5  45 

2.6  58 

2.7  68 


Feet.  Second-feet. 

2.8  74 

2.9  86 
8.0  98 


he^^t.      I>i8charge. 


Feet.  Second-feet. 

3.1  112 

8.2  126 

8.3  140 


Month. 


ESTIMATED  MONTHLY  DISCHARGE  OF  RIO  VIEJO  AT  CROSSING  OF  MATAGALPA- 
LEON  ROAD. 


Discharge  in  Second-Feet.       Total  in 
Maximum.    Minimum.    M<«n.  Acre-Feet. 


Month. 


Discharge  in  Second-Feet. 

, * , 

Maximum.    Minimum.    Mean. 


Total  in 
A  ere- Feet. 


1898. 

Fcbniary 36 

March 25 

April 5 

May 5,520 

June 15,600 

July 2,400 

August 2,750 


15 

24 

1,882 

5 

18 

800 

3 

3.0 

214 

2 

824 

19,920 

50 

2,170 

129, 120 

155 

618 

87,680 

125 

380 

20,290 

209,356 

1898. 

September 

October 

November 

December 

1899. 
January 

Total 


Brought  forward,  209,856 


9,745 

8,830 

253 

92 


220 

280 

74 

39 


1,765 

965 

130 

59 


105,025 

59,340 

7,785 

3,630 


Totol  for  1898 385,086 

94  35  49  8,018 

.388,099 


Rio  Xueva. 
This  station  was  established  February  1,  at 
the  bend  of  Rio  Nueva,  where  it  approaches 
nearest  Rio  Viejo,  in  the  neighborhood  of  Paso 
Real,  and  was  intended  to  throw  light  on  the 
quantity  of  water  that  might  be  added  to  the 
supply  for  Lake  Managua  by  diverting  this  river 
into  it. 


Measurements  were  made  by  wading  at  low 
water  and  by  means  of  floats  at  high  water.  The 
stage  of  the  river  was  ascertained  by  measuring 
downward  with  a  tape-line  from  a  nail  driven 
in  an  overhanging  trunk  of  a  tree.  These 
measurements  were  carried  on  by  the  same  ob- 
server  who  had  charge  of  the  station   at  Rio 

'XT'      • 

A  lejo. 


Date. 

1H08. 


LIST  OF  DISCHARGE  MEASUREMENTS  MADE  ON  RIO  NUEVA  NEAR  RIO  VIEJO. 


Hydroffraphcr. 


May    28 G.  P.  Philip 

27. 
June     8. 

»'  10. 
'»  17. 
«*  24. 
July  1. 
8. 
**       15. 


ii 
ti 
tt 
(t 
i( 
ii 
(i 
li 
tt 


Meter 
number. 

Gag© 
heiffht 

(feet). 

Area  of 
section 

(sq.  ft.). 

Mean  ve- 
locity (ft 
per  sec.). 

Dischai«o 
(second- 
feet.). 

Remarks. 

Floats. 

5.0 

178 

2.54 

451 

it 

4.3 

126 

2.18 

275 

7 

8.0 

50 

0.70 

35.4 

Floats. 

8.42 

71 

1.82 

9S.6 

« 

7 

.3.02 

57 

0.69 

39.5 

Floats. 

18.10 

490 

4.81 

2861 

New  Gag:e-Rod. 

ti 

14.80 

280 

8.01 

698 

it 

14.70 

223 

2.79 

622 

it 

14.30 

198 

2.29 

441 

it 

18.0 

105 

1.87 

143 

APPENDIX  III.— HYDROGRAPHIC   REPORT 


207 


LIST  OP  DISCHARGE  MEASUREMENTS  MADE  ON  RIO  NUEVA  NEAR  RIO  VIEJO.— Continued. 


Date. 
1888. 

Hydrographer. 

Meter 
number. 

Gaffe 
height 
(feet). 

Area  of 
section 
(sq.  ft). 

Mean  ve- 
locity (ft 
per  sec). 

Discharge 

(second-                 Remarks, 
feet). 

July   29 

.  .G.  P.  Philip 

Floats. 

13.4 

132 

2.14 

282 

"       29. . . . 

ti 

7 

13.4 

138 

2.03 

269 

Aug.  26 

ti 

Floats. 

12.5 

74 

1.86 

138 

Sept  17 

li 

ti 

15.0 

248 

2.84 

704                Approximation. 

*»       28... 

ii 

it 

15.8 

303 

2.71 

821 

Oct       3... 

...Fred.  Dayls 

ti 

14.1 

181 

2.35 

425 

14... 

ti 

it 

15.2 

265 

2.83 

750 

'*        22... 

ii 

it 

16.4 

850 

8.93 

1,376 

*'        81... 

ti 

it 

14.1 

181 

2.84 

514 

Noy.      6. . . 

it 

it 

13.8 

124 

2.76' 

348 

12... 

it 

i« 

13.5 

76 

2.47 

187 

19... 

ti 

ti 

12.80 

31 

2.22 

65.5 

24... 

it 

i« 

12.V0 

80 

1.97 

60 

28... 

it 

t« 

12.70 

80 

2.17 

66 

Dec.      4. . . 

t* 

7 

12.60 

48 

1.06 

51 

8... 

it 

7 

12.50 

45 

0.99 

45 

15   .. 

it            

7 

12.80 

42.5 

1.16 

49 

*»        21... 

ti 

7 

12.21 

36. 

0.77 

28 

'*        80... 

it 

7 

12.15 

34.6 

0.60 

20.7 

1899. 

Jan.       2... 

it 

7 

12.21 

38.8 

0.78 

80.8 

9... 

it 

7 

12.30 

40.3 

1.01 

40.7 

15... 

ti 

7 

12.19 

36.2 

0.71 

25.8 

RATING  TABLE  FOR  RIO  NUEVA  NEAR  RIO  VIEJO. 
This  table  is  applicable  only  from  June  24.  1898,  to  January  22,  1899. 


Gage 
height 

Discharge. 

Gage 
height 

Discharge. 

Gage 
height 

Discharge. 

Gage 
height 

Discharge. 

Gage 
height 

Discharge. 

Feet 

Second-feet 

Feet    1 

Second-feet 

Feet 

Second-feet 

Feet 

Second-feet. 

Feet 

Second- feet 

12.3 

80 

13.5 

300 

14.7 

590 

15.9 

1,080 

17.1 

1,660 

12.4 

90 

18  6 

820 

14.8 

625 

16.0 

1,125 

17.2 

1,720 

12.5 

105 

18.7 

840 

14.9 

660 

16.1 

1,170 

17.3 

1,780 

12.6 

120 

13.8 

360 

15.0 

700 

16.2 

1,215 

17.4 

1,850 

12.7 

140 

18.9 

880 

15.1 

740 

16.3 

1,260 

17.5 

1,920 

12.8 

160 

14.0 

400 

15.2 

780 

16.4 

1,305 

17.6 

1,990 

12.9 

180 

14.1 

425 

15.3 

820 

16.5 

1,850 

17.7 

2,060 

13.0 

200 

14.2 

450 

15.4 

860 

16.6 

1,400 

17.8 

2,130 

13.1 

220 

14.3 

475 

15.5 

900 

16.7 

1,450 

17.9 

2,200 

18.2 

240 

14.4 

500 

15.6 

945 

16.8 

1,500 

18.0 

2,280 

18.3 

260 

14.5 

530 

15.7 

990 

16.9 

1,550 

•   •   •   • 

13.4 

,       280 

14.6 

560 

15.8 

1,085 

17.0 

1,600 

•   •   •   • 

River  dry  from  February  13  to  May  20. 


QUEBRADA    Hoin)A. 

This  stream  is  tributary  to  Rio  Viejo  about 
two  miles  below  the  station  on  the  latter.  A 
gage  was  placed  one-half  mile  above  the  wagon 


ford  on  the  road  from  Leon  to  Matagalpa  and 
graduated  to  feet  and  tenths.  At  low  water, 
measurements  were  made  by  wading;  at  high 
water,  bv  means  of  floats. 


208 


NICARAGUA  CANAL  COMMISSION 


LIST  OF  DigCHARGE  MEASUREMENTS  MADE  ON  QUEBRADA  HONDA  ABOVE  CROSSING  OF 

MAT  AG  ALP  A- LEON  ROAD. 


Date. 

Rydrographer. 

Meter 
number. 

Gage 
height 

(feet). 

Area  of 
section 
(sq.  ft.). 

Moan  ve- 
locity (ft. 
per  sec.  )• 

Discharge, 
(second- 
feet). 

May     27... 

...J.  G.  Philips 

Floats. 

5.10 

112 

1.59 

178 

June     8... 

ti 

7 

4.10 

69 

0.27 

19 

10... 

ti 

Floats. 

4.88 

104 

1.65 

171 

17... 

n 

7 

4.22 

79 

0.32 

25 

»'        25... 

ti 

Floats. 

9.10 

276 

4.85 

1,200 

July      1... 

t( 

tl 

5.28 

109 

1.82 

198 

"        29. . . 

it 

7 

4.22 

74 

0.48 

35 

Aug.    26... 

u 

Floats. 

4.60 

88 

1.64 

145 

Sept.  28. . . 

tl 

tt 

5.68 

129 

2.18 

281 

Oct.      4... 

...Fred.    Dayls 

t( 

4.68 

89 

1.61 

144 

11... 

tl 

tt 

.      4.75 

98 

1.89 

176 

•»        28... 

It 

ti 

7.05 

184 

3.23 

593 

"        80... 

It 

ti 

4.62 

89 

1.72 

153 

Nov.     6... 

tt 

It 

4.80 

76 

1.01 

76 

12... 

tt 

it 

4.21 

78 

0.71 

52 

19... 

It 

it 

4.05 

68 

0.43 

29 

"        24. . . 

It 

it 

4.00 

65 

0.87 

24.5 

'*        28... 

It 

it 

3.98 

65 

0.36 

23.5 

Dec.      4... 

It 

7 

8.90 

8.5 

1.12 

9.5 

9... 

It 

7 

8.90 

7.5 

0.80 

6.0 

•*       16   .. 

tt 

7 

3.85 

7.5 

0.84 

6.3 

*'       22... 

tl 

to 
t 

3.80 

6.2 

0.59 

3.7 

**       28... 

It 

7 

8.80 

8.9 

0.48 

1.9 

TiPITAPA. 

A  gage  was  placed  in  this  river  about  100 
yards  above  Tipitapa  falls,  which  serves  both  to 
register  the  stage  of  the  river  and  the  height  of 
Lake  Managua  upon  which  the  stage  of  the  river 
depends.  During  low  water  the  river  was  too 
sluggish  above  the  falls  for  accurate  measure- 
ments with  current  meter,  and  gagings  were 
made  from  the  bridge  below  the  falls.  As  the 
river  rose  it  became  very  turbulent  and  swift  at 
the  bridge,  but  at  the  same  time  the  velocity  in 
the  upper  river  increased  and  good  measure- 
ments were  made  above  the  falls.  Observations 
of  rainfall  and  evaporation  were  also  made  at 
this  point. 

Lake  Managua  lies  to  the  northwest  of  Lake 
Nicaragua  and  drains  into  the  latter  through 


Eio   Tipitapa.     Its  area   is   about  438   square 
miles. 

Reports  of  the  discharge  of  Tipitapa  river  are 
conflicting.  All  agree  that  the  stream  goes 
dry  in  the  latter  part  of  every  dry  season.  Some 
authorities  assert  that  it  has  been  dry  for  several 
years  in  succession,  the  inflow  during  the  rainy 
season  being  insufiicient  to  compensate  for  evapo- 
ration, while  others  maintain  that  there  is  more 
or  less  outflow  every  year  in  the  rainy  season. 
Investigations  were  therefore  made  to  determine 
roughly  the  feasibility  of  diverting  the  Rio 
Nueva  which  now  drains  into  the  Rio  Grande, 
into  Rio  Viejo  and  finally  into  Lake  Managua. 
Near  the  station  on  Rio  Viejo  the  two  rivers 
approach  within  about  a  mile  of  each  other  and 
the  intervening  country  is  low  and  flat.  The' 
river  channels  are  30  to  40  feet  deep  and  a  cut 


APPENDIX   III.— HYDROGRAPHIC   REPORT 


209 


of  this  depth  connecting  the  two  could  be  made 
to  conduct  the  waters  of  Rio  Xueva  into  liio 
Viejo,  if  a  dam  were  built  in  Rio  Xueva  below 
the  point  of  connection.     There  is  rock  on  the 


bottom  of  Rio  Xueva  showing  fairly  good  foun- 
dation for  such  a  structure,  but  the  excavation 
of  the  canal  would  be  almost  entirely  in  alluvial 
earth. 


DAILY  GAGE  HEIGHT  OF  RIO  TIPITAPA  AT  TIPITAPA  ABOVE  FALLS  FOR  1898.* 


Day. 

1808. 

Feb. 

Mar. 

April. 

May. 

June. 

July. 

Aug. 

Sept. 

Oct. 

Nov. 

Doc. 

Jan. 
180U. 

1 

4.44 

8.92 

3.10 

2.65 

3.61 

5.41 

5.19 

5.72 

7.34 

8.05 

7.05 

6.20 

2 

4.89 

3.92 

3.13 

2.56 

3.61 

5.50 

5.27 

5.70 

7.34 

7.95 

7.10 

6.20 

3 

4.42 

8.92 

•   •   •    • 

2.59 

8.59 

4.90 

5.27 

5.66 

7.30 

7.90 

7.00 

6.20 

4 

4.83 

3.89 

2.91 

2.55 

8.53 

5.39 

5.33 

5.76 

•   •   •   • 

7.80 

6.95 

6.18 

5 

4.35 

8.81 

8.10 

2.54 

8.62 

5.36 

5.24 

5.90 

7.25 

7.80 

6.90 

6.15 

6 

4.38 

3.78 

3.12 

2.54 

8.68 

5.53 

5.27 

5.t)0 

7.25 

7.75 

6.85 

6.10 

7 

4.36 

3.78 

3.08 

2.52 

8.65 

5.68 

5.88 

5.90 

7.30 

7.75 

6.85 

6.08 

8 

4.32 

3.80 

2.99 

2.49 

8.62 

5.44 

5.37 

5.70 

7.40 

7.70 

6.80 

6.00 

1) 

4.32 

•   •   •   • 

2.97 

2.47 

8.62 

5.36 

5.26 

5.94 

7.35 

7.65 

6.75 

5.98 

10 

4.28 

3.81 

2.93 

2.48 

3.69 

5.60 

5.20 

5.96 

7.40 

7.70 

6.75 

6.00 

11 

4.25 

3.78 

2.95 

2.49 

8.71 

5.42 

5.23 

6.14 

7.85 

7.65 

6.72 

5.90 

12 

4.23 

3.75 

2.86 

2.45 

3.91 

5.47 

5.33 

6.28 

7.35 

7.65 

6.70 

5.95 

13 

4.12 

3.78 

2.97 

2.45 

3.71 

5.49 

5.24 

6.48 

7.32 

7.70 

6.70 

5.85 

14 

4.17 

8.74 

2.98 

2.39 

3.66 

5.50 

5.31 

6.62 

7.40 

7.60 

6.65 

5.85 

15 

4.20 

8.68 

2.95 

2.42 

3.65 

5.42 

5.37 

6.78 

7.37 

7.55 

6.60 

5.90 

16 

4.18 

3.57 

2.96 

2.47 

3.67 

5.34 

5.29 

6.95 

7.50 

7.50 

6.55 

5.88 

17 

4.11 

3.52 

2.84 

2.52 

3.77 

5.48 

5.31 

6.94 

7.62 

7.40 

6.55 

5.85 

18 

4.18 

3.51 

2.91 

2.67 

3.88 

5.32 

5.28 

6.94 

7.72 

7.45 

6.50 

5.88 

19 

4.11 

8.48 

2.86 

2.82 

3.89 

5.38 

5.27 

6.95 

7.72 

7.35 

6.55 

5.80 

20 

4.16 

3.41 

2.78 

2.80 

4.03 

5.82 

5.27 

6.96 

7.87 

7.30 

6.50 

5.85 

21 

4.08 

8.41 

2.78 

2.92 

4.12 

5.86 

5.31 

7.18 

7.95 

7.30 

6.52 

5.70 

22 

4.05 

3.40 

2.77 

3.08 

4.51 

5.48 

5.31 

7.18 

7.95 

7.30 

6.50 

5.75 

28 

4.05 

3.50 

2.79 

8.18 

4.62 

5.40 

5.41 

7.18 

8.00 

7.25 

6.45 

5.72 

24 

4.01 

3.43 

2.80 

8.38 

4.76 

5.33 

5.36 

7.24 

7.92 

7.25 

6.40 

•   •   •   • 

25 

8.94 

3.34 

2.79 

8.57 

4.86 

5.31 

5.35 

7.26 

7.95 

7.20 

6.40 

•   •   •   • 

26 

3.93 

3.21 

2.68 

8.67 

4.95 

5.40 

5.38 

7.20 

7.95 

7.20 

6.35 

•   •   •   ■ 

27 

8.96 

8.26 

2.62 

3.70 

4.87 

5.26 

5.42 

7.31 

8.00 

7.15 

6.80 

•   •   •   • 

28 

8.95 

8.30 

2.65 

3.67 

5.16 

5.25 

5.64 

7.38 

8.02 

7.15 

6.30 

•  •   •  • 

29 

•   •   •   • 

3.28 

2.67 

3.68 

5.38 

5.26 

5.60 

7.40 

8.00 

7.10 

6.25 

•   •   •   • 

80 

•  •   •   • 

3.1G 

2.60 

3.58 

5.48 

5.30 

5.68 

7.34 

8.00 

7.05 

6.20 

•   •  •   • 

81 

•   •   •   • 

3.13 

•    •   •   • 

3.65 

•   •   •   • 

5.39 

5.69 

•    •   •   • 

8.00 

•   •    •   ■ 

6.20 

•   •   •  • 

*  This  table  also  indicates  the  fluctuations  of  Lake  Mauagua. 


LIST  OF  DISCHARGE  MEASUREMENTS  MADE  ON  RIO  TIPITAPA  AT  TIPITAPA. 


No. 


1 
2 
3 

4 
5 
6 


Date. 
1898 


Hydrogrrapher. 


Meter 
number. 


Gage  Area  oU       Mean  ve-      Discharge 

height  section       locity  (feet       (secono- 

(feet).      (square  ft.),    per  second)         feet). 


Apr.     2 G.  P.  Philip Ellis 

May  26 G.  N.  Challlce 

June    1 

»*    16 

«*    20 

**    22 *' 


4( 


(t 


(( 


8.13 
3.67 
8.58 
3.67 
4.04 
4.50 


8.2 

0.79 

4.5 

0.47 

46 

0.27 

45 

0.32 

60 

0.82 

99 

1.51 

2.6 
21 
12 
15 
49 
149 


Remarks. 


14 


210 


NICARAGUA  CANAL  COMMISSION 


LIST  OF  DISCHARGE  MEASUREMENTS  MADE  ON  RIO  TIPITAPA  AT  TIPITAPA.— Continued. 


I 


I 


r: 


r 
II 


ii 


i: 


i; 


No. 

Dat«. 

1898. 

Hydrographer. 

Meter 
number. 

7 

June  27. . . . 

..G. 

N.  Challlce 

.       Ellis 

8 

July     1. . . . 

R.  Wadlelgh . . . . . 

t( 

ti 

9 
10 

Aug.  18 

"    29.... 

..G. 

it 
it 

11 
12 

Sep.     5. . . . 
«*    10.... 

ti 

it 

it 

13 

**    12.... 

ti 

tt 

14 

"    13.... 

tt 

tt 

15 

»*    14.... 

it 

it 

10 

**    15.... 

tt 

it 

17 

"    16... 

tt 

it 

18 

»*    21 

tt 
it 
tt 

P.  Philip  .  *.  *. '. .'  .* ! 

tt 

,           it 

19 

"    26 

tt 

20 

u    28 

it 

21 
22 

Oct.   10.... 
*'    22.... 

..G. 

tt 
,           tt 

28 

Nov.    2.... 

tt 

it 

24 

it      4 

tt 

tt 
tt 
ti 

tt 

25 

'*      9. . . . 

it 

26 

♦»    12 

tt 

27 

"    19.... 

tt 

28 

*'    23.... 

tt 

it 

29 

Dec.     2 

tt 

it 

80 

«*      6 

tt 

tt 

it 

81 

"    13 

tt 

32 

"    20.... 

tt 

,           it 

83 

"    26.... 
1899. 

tt 

,           tt 

34 

Jan.     1 

tt 

tt 

35 

"      7 

tt 

tt 

86 

**    10 

it 

tt 

37 

«*    20.... 

tt 

it 

Gage 

height 

(feet). 


Area  of        Mean  ve-      Disohargo 
section       locity  (feet     (second- 
(square  f  t.).    per  second).       feet). 


Remarks. 


4.81 

119 

5.40 

195 

5.27 

177 

5.60 

178 

5.85 

196 

5.98 

1,346 

6.23 

1,495 

6.44 

1,602 

6.58 

1,601 

6.74 

1,659 

6.94 

1,738 

7.18 

1,834 

7.18 

1,885 

7.36 

1,909 

7.40 

1,894 

7.94 

2,158 

7.92 

2,140 

7.82 

2,103 

7.69 

2,038 

7.53 

1,937 

7.42 

1,925 

7.25 

1,862 

7.08 

1,785 

6.85 

1,684 

6.70 

1,608 

6.52 

1,571 

6.38 

1,454 

6.22 

1,400 

6.08 

1,874 

6.03 

1,342 

5.75 

1,242 

1.98 

236 

8.43 

669 

3.38 

597 

4.75 

845 

6.61 

1,296 

0.84 

1,187 

0.98 

1,894 

1.11 

1,771 

1.19 

1,907 

1.27 

2,106 

1.88 

2,892 

1.55 

2,851 

1.62 

2,966 

1.71 

8,186 

1.71 

8,284 

2.40 

5,177 

2.29 

4,891 

2.25 

4,735 

2.12 

4,325 

1.85 

8,585 

1.79 

8,445 

1.66 

8,095 

1.57 

2,810 

1.46 

2,465 

1.86 

2,191 

1.24 

1,985 

1.17 

1,704 

1.07 

1,500 

1.00 

1,375 

0.98 

1,814 

0.81 

1,000 

1,500    strong  wind  up-stream. 

1,375 

1,814 

1,000    strong  wind  up-stream. 


RATING  TABLE  FOR  RIO  TIPITAPA  AT  TIPITAPA. 
This  table  is  applicable  only  from  February  1,  1898,  to  January  23,  1899. 


Gage 
height. 

Discharge. 

Gage 
height. 

Discharge. 

Gage 
height. 

Discharge. 

Gage 
height. 

Discharge. 

Gage 
height. 

Discharge. 

Feet 

Second-feet. 

Feet. 

Second-feet. 

Feet. 

Second-feet. 

Feet. 

Second-feet. 

Feet.     Second-feet. 

8.0 

1 

4.1 

61 

5.1 

410 

6.1 

1,860 

7.1 

2,630 

3.1 

2 

4.2 

79 

5.2 

495 

6.2 

1,470 

7.2 

2,810 

8.2 

4 

4.3 

96 

5.3 

580 

6.3 

1,580 

7.3 

3,010 

8.3 

6 

4.4 

116 

5.4 

670 

6.4 

1,690 

7.4 

8,280 

8.4 

8 

1.5 

137 

.   5.5 

760 

6.5 

1,800 

7.5 

3,500 

3.5 

10 

4.6 

162 

5.6 

850 

6.6 

1,920 

7.6 

3,800 

8.6 

13 

4.7 

195 

5.7 

950 

6.7 

2,050 

7.7 

4,130 

8.7 

18 

4.8 

230 

5.8 

1,050 

6.8 

2,180 

7.8 

4,500 

8.8 

25 

4.9 

280 

5.9 

1,150 

6.9 

2,320 

7.9 

4,900 

3.9 

84 

5.0 

340 

6.0 

1,250 

7.0 

2,470 

8.0 

5,800 

4.0 

46 

ESTIMATED  MONTHLY  DISCHARGE  OF  RIO  TIPITAPA  AT  TIPITAPA. 

Month. 

Discharge  in  Second-Feet.       Total  in 
Maximum.    Minimum.    Mean,  ^^^^^^^' 

Month. 

Discharge  in  Second-Feet.       ^ata\  in 
Maximum.    Minimum.    Mean.  ^^"^^®®^ 

1898 

1898. 

Brought  forward,  91,948 

February  . 

125 

87 

77 

4,275 

September 

8,280 

910 

2,045 

121,690 

March  .... 

36 

3 

16.6 

1,020 

October  

5,880 

2,910 

4,040 

248,410 

April 

4 

0 

0.5 

29 

November 

5,500 

2,150 

3,640 

210,600 

May 

18 

0 

3.8 

234 

December 

2,630 

1,470 

1,950 

119,900 

June 

700 

13 

121 

7,200 

1899. 

Total  for  1898 

798,.548 

July 

August. . . 

922 
930 

280 
487 

662 
626 

40,700 
88,490 

January  (1-23).. 

1,470 

950 

1,210 

.55,200 

91,948 

Total 

853,748 

APPENDIX  m.— HYDROGRAPHIC  REPORT 


Fio.  3.    Diagram  ot  Daily  Discbarge  of  Rio  Tlpltapa,  1S98. 


Sas  Ubaijm)  ahd  Mokbito. 
For  the  purpose  of  measuring  evaporation 
and  rainfall  on  the  northeastern  shore  of  Lake 
Xicaragua  as  well  as  recording  its  fluctuations, 
a  station  was  estaWished  at  San  Fbaldo  on  April 
0,  1898.  This  point  was  selected  on  account 
of  the  convenience  of  communication,  it  l>cing 
a  regular  stopping  place  for  the  "  Victoria,"  a 
steamer  plying  between  Granada  and  San  Carlos. 
During  the  month  of  May,  when  adverse  winds 
were  frequent,  the  evaporation  pan  was  fre- 
quently driven  ashore,  there  being  no  means  of 
protecting  it  at  this  point.  This  fact,  together 
with  the  difficulty  of  obtaining  suitable  quarters 
for  the  obsener  at  this  point,  decided  the  re- 
moval of  this  station  to  Jlorrito,  a  native  village 
about  ten  miles  to  the  southeast.  This  removal 
was  accomplished  on  ilay  24.  The  lake  gage 
at  San  Ubaldo  was  connected  by  spirit  level  with 
two  bench  marks  and  with  a  point  indicated  by 
the  inhabitants  as  being  the  high-water  mark  of 
1893,  the  highest  stage  known  since  the  settle- 
ment at  this  point 


Bench  mark  Xo.  1  is  the  highest  point  of  a 
large  boulder  ten  feet  north  of  the  north  door  of 
the  Bodega.  It  is  5.44  feet  above  the  9-ft,  mark 
of  the  lake  gage. 

Bench  mark  Xo.  2  is  on  top  of  the  middle 
masonry  support  of  tlio  Bodega  building.  It  is 
5,3  feet  above  tlic  Oft.  mark  of  the  lake  gage. 

The  high-water  mark  of  1893  is  3,9  feet  above 
the  9-ft,  mark  of  the  lake  gage.  Rainfall  and 
evaporation  obser\'ations  were  also  taken  at  this 
station. 

At  Jlorrito  the  gage  was  fastened  to  some 
stakes  that  had  been  standing  in  the  mai^n  of 
the  lake  for  some  years  and  were  reasonably 
solid.  Both  it  and  the  evai>oration  pan  were 
partially  protected  from  breakers  by  a  line  of 
swamp  grass  growing  in  the  lake  outside  of  the 
water  in  which  they  stood.  This  station  was 
discontinued  on  September  21. 

Station  at  Fort  Sa\  Carlos. 

A  gage  was  establi.ihed  at  this  point  by  Lieut. 

Ilanus,   r.   S.   N.,   Januarv   4,   1898.     It  was 


212 


NICARAGUA  CANAL  COMMISSION 


simply  a  graduated  stick  driven  in  the  sand  in 
shallow  water  and  supported  by  two  stakes  in  the 
form  of  braces.  On  March  13  a  more  substan- 
tial gage  was  placed  in  deeper  water  and  firmly 
fastened  to  the  iron  remains  of  an  old  wreck  of  a 
Vandcrbilt  steamer  about  a  quarter  of  a  mile 
north  of  the  town  of  San  Carlos.  It  was  driven 
as  far  as  possible  into  the  mud  and  fastened  with 
bolts  and  cable  to  the  iron  wreck. 

Bench  mark  Xo.  1  is  on  the  highest  point  of 
the  shore  end  of  the  stranded  boiler  and  is  12. 


933  feet  above  the  zero  water  gage  last  described 
and  9.78  feet  above  the  zero  of  gage  established 
by  Lieut.  Hanus.  From  the  8th  of  March,  when 
a  special  observer  was  stationed  at  San  Carlos, 
rainfall,  evaporation,  temperature  and  humidity 
observations  were  taken. 

On  May  9th  a  gage  was  placed  in  Rio  Frio 
about  one  mile  above  its  mouth,  upon  which 
readings  were  taken  every  other  day,  and  oc- 
casional measurements  were  made. 


DAILY  ELEVATION  OF  LAKE  NICARAGUA. 

Computed  from  gage-rod  readings  at  Fort  San  Carlos,  Jan.  4, 1898,  to  March  31,  1899;  Las  Lajas,  Feb.  8,  1898, 
to  March  31,  1899;  Morrito,  April  9,  1898,  to  Sept.  21,  1898;  and  Granada,  Feb.  1,  1899,  to  March  31,  1899. 


18Q8. 

Jan. 

Feb. 

Mar. 

Apr. 

May. 

June. 

July. 

Aug. 

Sep. 

Oct. 

Nov. 

Doc. 

lovv. 

Jan. 

Feb. 

Mar. 

Day. 

A  •   •   •   • 

• . . « 

104.49 

103.86 

103.02 

102.29 

102.48 

103.50 

104.56 

104.96 

105.66 

106.41 

106.64 

106.31 

10.5.81 

105.13 

2... 

.... 

104.42 

103.89 

103.02 

102.24 

102.49 

108.47 

104.51 

104.97 

105.74 

106.37 

106.63 

106.30 

105.81 

105.00 

8 . . . . 

.... 

104.52 

103.82 

102.98 

102.23 

102.44 

103.55 

104.51 

104.95 

105.76 

106.31 

106.59 

106.29 

105.77 

104.99 

4.... 

104.92 

104.48 

103.86 

102.96 

102.21 

102.39 

103.70 

104.58 

104.94 

105.74 

106.26 

106.65 

106.22 

10.5.74 

105.00 

5 . .  . . 

104.96 

104.51 

103.78 

102.92 

102.20 

102.42 

103.62 

104.61 

104.97 

106.75 

106.22 

106.67 

106.26 

105.71 

104.96 

6. . . . 

ia5.02 

104.48 

103.75 

102.96 

102.20 

102.45 

103.78 

104.57 

10.5.05 

105.73 

106.26 

106.62 

106.22 

10.5.72 

104.92 

7.... 

104.93 

104.43 

103.76 

102.92 

102.14 

102.52 

103.79 

104.60 

105.02 

105.75 

106.22 

106.04 

106.16 

105.70 

•   •   •   • 

o  •  •  •  • 

104.94 

104.43 

108.78 

102.86 

102.12 

102.49 

103.82 

104.70 

105.05 

105.79 

106.19 

106.56 

106.22 

105.67 

104.95 

9.    .. 

104.88 

104.42 

103.72 

102.83 

102.11 

102.48 

103.90 

104.67 

105.05 

105.73 

106.22 

106.55 

106.18 

105.63 

104.90 

10.... 

104.79 

104.32 

103.62 

102.77 

102.09 

102.48 

103.89 

104.65 

105.11 

ia5.73 

106.21 

106.68 

106.17 

105.60 

104.87 

11 

104.85 

104.30 

103.64 

102.81 

102.08 

102.48 

108.96 

104.65 

10.5.19 

105.71 

106.26 

106.57 

106.19 

105.64 

104.74 

12 

104.87 

104.81 

103.62 

102.81 

102.04 

102.54 

103.99 

104.59 

.105.29 

105.75 

106.84 

106.55 

106.15 

105.66 

104.73 

18 

104.80 

104.41 

103.61 

102.76 

101.96 

102.51 

103.98 

104.74 

105.44 

105.75 

106.46 

106.49 

106.14 

10.5.65 

104.67 

14.... 

104.76 

104.82 

103.52 

112.74 

102.03 

102.47 

10.3.98 

104.73 

105.45 

105.K4 

106.42 

106.49 

106.09 

10.5.57 

104.68 

15 

104.75 

104.29 

108.57 

102.69 

101.97 

102.48 

104.03 

104.78 

105.48 

105..  88 

106.47 

106.47 

106.16 

105.52 

104.67 

16.... 

104.79 

104.23 

•   •   •   • 

102.68 

102.05 

102.44 

104.07 

104.80 

10.5.. 53 

105.86 

106.50 

106..50 

106.09 

105.51 

104.70 

17 

104.78 

104.21 

•   •    •   • 

102.68 

102.01 

102.47 

104.04 

104.83 

105.58 

105.92 

106.50 

106.44 

106.09 

105.46 

104.62 

18.... 

104.83 

104.21 

•   «   •   • 

102.65 

102.13 

102.47 

104.07 

104.78 

105.57 

106.08 

106.57 

106.44 

106  13 

105.43 

104.61 

19.... 

104.84 

104.16 

103.26 

102.61 

102.10 

102.59 

104.10 

104.78 

10.5.57 

106.14 

106.51 

106.39 

106.13 

105.41 

104.49 

20 

104.97 

104.14 

108.30 

102.55 

102.11 

102.65 

104.25 

104.78 

105.58 

106.15 

106.44 

106.41 

106.15 

105.43 

104.65 

21 

104.90 

104.08 

103.33 

102.59 

102.15 

102.70 

104.17 

104.82 

105.65 

106.18 

106.62 

106.37 

106.06 

105.30 

104.51 

22.... 

104.82 

104.04 

108.14 

102.  .56 

102.43 

102.91 

104.25 

104.83 

105.71 

106.24 

106.56 

106.82 

106.02 

105.26 

104.42 

28.... 

104.73 

104.00 

103.27 

102.53 

102.40 

102.97 

104.23 

104.77 

105.66 

106.28 

•   ■   •   • 

106.37 

105.96 

105.24 

104.45 

24... 

104.64 

104.08 

103.29 

102.45 

102.51 

103.01 

104.32 

104.80 

105.74 

106.36 

•   •   •   • 

106.39 

105.92 

10.5.32 

104.37 

25 

104.71 

104.04 

103.30 

102.43 

102.57 

103.09 

104.33 

104.81 

105.72 

106.35 

•   •   •   • 

106.85 

105.96 

105.18 

104.34 

26 

104.70 

104.06 

103. 99 

102.44 

102.. 55 

103.04 

104.35 

104.78 

105.68 

106.36 

106.54 

106.33 

105.94 

105.28 

104.82 

27 

104.69 

103.94 

103.19 

102.42 

102.59 

103.16 

104.39 

104.83 

105.63 

106.38 

106.59 

106.29 

105.89 

10.5.15 

104.25 

28 

104.07 

103.93 

103.12 

102.37 

102.56 

103.30 

104.46 

104.82 

105.74 

106.34 

106.62 

106.27 

105.86 

105.11 

104.26 

29.... 

104.52 

•   •   •   • 

103.09 

102.33 

102.46 

103.42 

104.38 

104.94 

105.76 

106.44 

106.63 

106.38 

105.87 

•    •    •   • 

104.25 

80 

104.64 

•   •   ■   • 

103.10 

102.32 

102.55 

103.47 

104.54 

104.95 

ia5.75 

106.41 

106.70 

106.37 

105.83 

•   •   ■ 

104.27 

31.... 

104.57 

•    •    •   • 

102.97 

•   •   •   • 

102.50 

•   •   •    • 

104.51 

104.96 

• . . . 

106.38 

•   •  •   t 

106.44 

105.85 

•    •   •    • 

104.23 

APPENDIX   III.— HYDROGRAPHIC  REPORT 


213 


ESTIMATED  MONTHLY  FLOW  INTO  LAKE  NICARAGUA  IN  EXCESS  OF  EVAPORATION. 

"""th-                                  ^""^Xr"^  Ac^tcet  outflow.  TotaUnacn^  Inflow^.n 

189S. 

January,  4-31  Inclusive —666,400  + 1,032,400                          +366,000  +6,590 

February —1,218,600  +  923,800                          -2m,800  —5,310 

March -1,827,800  +863,600                          —964,200  —15,680 

April —1,237,600  +724,100                          —513,500  -8,630 

May +842,700  +723,300  +1,066,000  +17,340 

June +1,846,900  +841,600  +2,688,500  +45,200 

July +1,080,200  + 1,190,900  +3,171,100  +51,570 

August +856,800  +1,202,200  +2,050,000  +38,490 

September +1,504,200  + 1,313,600  +2,817,800  +47,350 

October + 1,199,500  +1,440,600  +2,640,100  +42,960 

November +609,300  +1,512,000  +2,121,300  +85,650 

December   —495,000  + 1,540,000  +  1,045,000  + 16,990 

Total  for  1898 +  16,202,300 

1899. 

January —1,128,400  + 1,443,100                          +819,700  +5,300 

February — 1,409,000  + 1,154,600                          —254,400  —4,580 

March - 1,680,500  + 1,103,700                          —576,800  —9,880 


LIST  OF  DISCHARGE  MEASUREMENTS  MADE  ON  RIO  FRIO  ONE  MILE  ABOVE  MOUTH. 


Date.               Hy<In>Krapber. 

Meter 
Number. 

III 

Area  of 
section 
(sq.  ft). 

Moan  ve- 
locity (ft. 
per.  SCO.). 

Discharge, 
(second- 
feet). 

May     13 II.  S.  Reed 

St.  1 

2.63 

2,375 

0.51 

1,198 

'«          9 "          

1 
1 

1 
1 

2.50 
2.62 
2.93 
3.85 

2,414 
2,414 
2,519 
2,660 

0.54 
0.30 
0.74 
2.49 

1,802 

i*        15 »'          

787 

»«        21 *'          

1,871 

June   22 W.  W.  Schlecht 

6,626 

30.... 

1 

4.67 

2,928 

3.96 

11,600 

July      9 *'                

1 

4.90 

2,947 

3.74 

11,082 

"       23.... 

1 

5.10 

3,068 

3.84 

11,780 

"       29.... 

1 

5.20 

3,088 

2.40 

7,400 

**       23.... 

Floats. 

5.05 

3,060 

3.56 

10,885 

Aug.      6 *'                

St.  1 

5.25 

3,096 

2.48 

7,684 

"        19 ''                ... 

1 

5.28 

3,096 

2.40 

7,445 

»*        31 E.  P.  Humphrey 

94 

5.44 

3,095 

1.36 

4,187 

Sept.    13 ''               

94 

5.80 

3,438 

1.45 

5,003 

Dry  Season  Inflow  to  Lake  Nicaragua. 

For  the  purpose  of  determining  the  amount 
of  storage  necessary  for  maintaining  the  summit 
level  of  Lake  Nicaragua  at  any  desired  point 
through  the  dry  season,  an  attempt  was  made  to 
measure  the  inflow  to  Lake  Nicaragua  during  the 
months  of  April  and  !May  1898.     This  work 


was  begun  on  April  19,  and  the  following  notes 
and  measurements  were  made  of  its  tributaries; 
Negro  (?). — First  river  south  of  Rio  Frio. 
Water  black  and  foul.  No  current.  Open 
water  only  about  300  yards  above  mouth. 
Above  this  entirely  closed  by  grass.  Width,  40 
to  200  feet;  depth,  8  to  12  feet;  discharge,  zero. 


214 


NICARAGUA  CANAL  COMMISSION 


Another  estuary  exactly  similar  in  all  respects 
occurs  one-fourth  of  a  mile  south,  which  may  be 
another  mouth  of  the  same  drainage.  Both  are 
almost  due  south  of  San  Carlos. 

A  third  estuarv,  wider  and  longer,  but  other- 


above  mouth  the  channel  is  choked  with  vegeta- 
tion and  becomes  a  swamp. 

West  of  this  point  occurred  several  streams 
with  measurable  discharge.  Their  character  and 
volume  are  indicated  in  the  following  table: 


Date. 


April  19. 


April  20. 


April  21. 


May  15. 


Stream. 

Pisote,  cast  fork 

Pisote,  west  fork 

El  Toro 

Las  Haciendas,  1  mile  up 

Oroci,  near  mouth 

Mena,  %  mile  up 

Sabalo,  near  mouth 

Rio  Pueblo,  y^  mile  ^P 

Tiroli,  K  mile  up 

Sapoa,  2  miles  up 

Frio,  2  miles  up 

Total  dry  season  inflow  to  Lake  Nicaragua,  southern  end 


Ar<?a 
sec.-ft. 


550 
427 

78 

57 

47 

20 

2.3 

3.1 

102 

2,414 


Veloc. 
ft.  i>er  sec. 


Dis. 

8©C.~Xl» 


.82- 
.78 

1   oo 

.55 
.91 
1.70 
1.17 
.82 
.29 
.81 


452 
883 
No  discharge. 
95 
88 
48 
84 
2.7 
1.8 
80 
737 


1,760 


wise  similar,  is  one-half  mile  still  farther  south 
and  has  two  branches,  the  southern  and  longer 
being  two  miles  long.  Water  foul.  Discharge, 
zero  or  nearlv  so. 

Two  other  small  estuaries  were  inspected 
farther  south. 

CuoABACHO  (?). — A  wide-mouthed  deep  estu- 
ary about  a  mile  southwest  of  the  most  south- 
erly described  above.  It  has  about  a  mile  of 
open  water.  "So  indication  of  current  Water 
very  black.     Discharge,  zero. 

One-half  mile  southwest  of  above  occurs  an 
estuary  which  is  choked  with  vegetation  one- 
fourth  mile  above  its  mouth.     Discharge,  zero. 

One-half  mile  southwest  of  above,  a  deep 
estuary  closed  with  vegetation  one-half  mile 
above  its  mouth.     Discharge,  zero. 

Rio  Arana. — Went  up  about  one  mile  in 
canoe.  Water  deep  and  still.  Water-lettuce  and 
other  plants  standing  on  surface,  not  fastened, 
do  not  float  out.  Water  stagnant  and  foul.  All 
signs  indicate  absolutely  still  water.     One  mile 


Alligator. — Five  miles  north  of  San  Carlos 
an  estuaiy  of  stagnant  water,  10  feet  deep,  40 
feet  wide.  One-half  mile  above  mouth  it  is 
choked  with  vegetation.     Discharge,  zero. 

CoNsuELO. — Large  estuarj'  with  large  delta 
and  two  mouths.  Has  about  half  a  mile  of  open 
water;  above  this  point  closed  by  vegetation. 
Water  stagnant.     Discharge,  zero. 

MuRiLLO. — Xorth  of  Point  Murillo  is  an  estu- 
arv w^hich  forks  about  one-fourth  mile  above 

if 

mouth.     Both  forks  ai'e  closed  by  vegetation  a 
short  distance  above  their  junction.     Depth,  3 

to    7   feet.      No   measurable    velocity.      Total 

I.' 

discharge  estimated  at  10  second-feet. 

La  Maria. — ^About  two  miles  north  of  above 
is  a  short  estuary  of  stagnant  water.  Discharge, 
zero. 

TuLE. — Large  estuary,  wide  and  deep.  Much 
floating  vegetation.  No  perceptible  current. 
Discharge  insignificant. 

Sax  Miguelito. — An  estuarv  about  a  mile 
long  occults  two  miles  north  of  the  town  of  San 


APPENDIX   III— HYDROGRAPHIC   REPORT 


215 


Migiielito,  emptying  into  a  sort  of  bay.  It  is 
shallow  and  has  no  measurable  current.  Dis- 
charge, zero. 

Rio  Piedras. — A  large  deep  estuary  just 
north  of  above.  It  has  two  tributaries,  one 
from  the  right  and  one  from  the  left^  all  deep 
and  stagnant.  Floating  islands  and  plants  in- 
dicate no  current.     Discharge,  zero. 

Tepenaguasapa. — Large  estuary  with  large 
delta.  Depth  18  feet,  width  50  feet.  At  time 
of  inspection  floating  islands  and  other  vegeta- 
tion, were  moving  upstream  under  the  influence 
of  wind.  All  indications  point  to  stagnancy  as 
in  other  streams.     Discharge  negligible. 

Ollate. — This  river  has  a  large  deltaic  forma- 
tion covered  with  aquatic  vegetation,  much  of 
which  is  floating.  At  time  of  inspection  it  was 
choked  with  vegetation,  there  being  no  visible 
current.  Discharge  negligible.  About  one 
month  later,  on  the  21st  of  June,  a  measurement 
was  made  about  two  miles  above  the  mouth  of 
the  river.  At  this  time  the  area  of  cross  sec- 
tion at  the  point  of  measurement  was  1079 
square  feet,  mean  velocity  3.94  feet  per  second, 
discharge  4258  cubic  feet  per*  second. 

Catabina  RrvEB. — ^A  large  stream  course  ex- 
plored to  a  distance  of  about  two  miles.  Depth 
10  to  15  feet;  width  about  100.  No  current. 
Information  from  natives  and  all  indications  de- 
note no  discharge. 

AjocuAPA. — This  river  opens  directly  against 
the  island  of  the  Jobo  group  that  lies  nearest 
the  shore.  It  has  a  large  delta  and  is  very  shal- 
low. Much  choked  with  floating  vegetation. 
Discharge,  zero. 


MoLLALEs. — When  ascended.  May  23,  this 
river  was  stagnant  from  the  mouth  nearly  to  the 
point  of  measurement,  what  slight  motion  was 
shown  being  upstream.  Descending  it  showed 
current  nearlv  all  the  wav  down.  This  fact, 
and  the  rise  of  one-tenth  foot  which  occurred 
at  the  point  of  measurement  during  inspection, 
indicate  that  most  of  the  discharge  is  due  to 
verv  recent  heavv  rains.  Measurements  made 
4  miles  above  mouth.  Total  area  Q^  square 
feet,  mean  velocity,  .73,  discharge,  49. 

EoBLADO. — This  stream  enters  the  lake  at 
Guapinolapa.  On  May  24,  the  date  of  inspec- 
tion, it  was  choked  with  vegetation  about  200 
feet  above  the  point  of  measurement  and  gives 
other  proofs  of  normal  stagnancy.  The  dis- 
charge found  is  doubtless  due  to  recent  heavy 
rains.  Total  area  of  cross  section,  25  square 
feet.  Mean  velocity,  .77  feet  per  second;  dis- 
charge, 19  second-feet. 

Xo  other  stream  of  measurable  discharge  was 
found  flowing  into  the  northern  end  of  Lake 
Nicaragua.  The  coast  bet^^^een  Granada  and 
Eivas  was  not  explored.  From  the  best  informa- 
tion obtainable  by  inquiry  it  is  concluded  that  the 
tributaries  between  these  points  contributed  only 
an  inconsiderable  quantity  of  water  at  the  close 
of  the  dry  season. 

South  of  Rivas  the  Rio  Medio  was  discharging 
early  in  May  about  one  cubic  foot  per  second. 

The  mouth  of  Rio  Las  Lajas  was  closed  in 
February  and  remained  so  until  late  in  May. 
Several  measurements  were  made  in  1899,  and 
are  given  below. 


216 


NICARAGUA  CANAL  COMMISSION 


LIST  OF  DISCHARGE  MEASUREMENTS  TO  DETERMINE  THE   DRY-SEASON   INFLOW  TO   LAKE 

NICARAGUA,  1899. 

Made  by  Alfred  Ahrling  and  Fred.  Davis. 


Date. 


Stream. 


Localit}'. 


Meter 
number. 


bei^t 
(ft.). 


Area  of 

sec.  (sq. 

ft). 


Mean  ve- 
locity (ft. 
per  aec.). 


Discharge 
(sec-ft.). 


Jan.  21. 
24. 
25. 
26. 
27. 
28. 
Feb.    1. 

2. 

8. 

4. 

5. 

6. 

6. 

6. 

6. 

6. 

7. 

7. 

7. 

8. 

8. 

8. 
10. 
11. 
18. 
13. 

18. 

14. 
14. 


"  15. 

"  15. 

"  18. 

'»  25. 

«•  26. 

»♦  26. 

"  27. 

"  27. 

•»  28. 

*»  28. 

"  28. 
Mar.    1. 

•»  3. 

«»  3. 

»'  8. 


Tule 

Dilate 

Catarina 

Acoyapa  

Mollales 

Cangrejal 

Zapote 

Guacalita 

Pisote  

Haciendas  .... 
MalacatoUa . . . 

Cafiitas 

Sardina 

Orocl 

Amapalo 

Tecolostate  . . . 

Mena 

Sabalo 

Santa  Clara  . . . 

Tortuga 

Sapoa  

Poderoso 

Majaste 

Tepenaguasapa 

Camastra 

Gil  Gonzales . . 

{Las  Lajas * ) 
Ochomogo.  / 

Cabeza  

Piedia   

Limon 

Medio 

Maria 

Murio 

Dilate 

Tule 

Zapote 

Tipitapa 

Pisote   

Haciendas  .... 

Oroci 

Mena 

Sabalo 

Sapoa  

Gil  Gonzalez. . 

Dchomogo 

MalacatoUa  . . . 


Juan  Mejia's  Ranch  . .        03 
Carraso^s  Ranch 93 

Hate  Grande 93 

Santa  Rosa 7 

•   • 

7 
7 
93 
7 
7 
7 


7 

7 

I  • 

7 
7 


7 
Telegraph  line 93 

•      ••••••  >• 

Station  Pueblo  Nueyo. 
Main  Road 7 


Carraso's  Ranch 93  3 

Mejia's  Ranch 93  0 

Curameria's  Ranch  ...        93  5 

Under  Bridge 1  4 

93  7 

Santo  Tomas 93  4 

La  Mina 93 

93  2 

93  2 

Pena  Blanca 93  2 

bar  across  mou 

La  Vulcan 93 

Tabacal 93  0 


9 


6 


8 


9 
60 


th. 


9 


661 
1246 


40 
251 

346 

115 
19.8 
12.4 
12.8 
79.6 


82.6 
66.4 

23.6 
250 

4.6 

180 


{ 


14.7 

5.8 
33.'J 

4.3 


195 

167 

245 

114 
84.7 
87.0 
23.5 

137 

85.0 
12.1 


0.40 

262 

0.18 

230 

•  •  •  • 

00.0 

•  •  •  • 

00.0 

0.90 

86.3 

•  •  •  • 

00.0 

1.80 

453 

.... 

00.0 

2.04 

708 

1.63 

188 

1.81 

85.8 

0.84 

10.3 

0.72 

9.2 

1.17 

93.5 

•  •  •  • 

00.0 

•  •  •  • 

00.0 

1.66 

137 

1.23* 

82 

•  •  •  • 

00.0 

0.66 

15.6 

0.49 

128 

•  •  •  • 

00.0 

1.75 

8.0 

0.60 

109.0 

•  •  a  • 

00.0 

0.97 

14.3 

1.27 

7.4 

1.56 

61.8 

1.00 

4.3 

•  •  •  • 

00.0 

•  •  •  • 

00.0 

•  •  •  • 

00.0 

•  •  •  • 

00.0 

•  •  •  • 

•  •  •  • 

00.0 

•  •  •  • 

1.76 

342 

3.41 

569 

1.10 

270 

1.12 

127 

1.30 

45.2 

2.15 

79.7 

1.44 

33.8 

0.50 

69.4 

1.79 

62.9 

1.68 

20.2 

*  This  Las  Lajas  is  a  branch  of  the  Gchomago. 


APPENDIX  III.— HYDROGRAPHIC   REPORT 


217 


LIST  OF  DISCHARGE  MEASUREMENTS  TO  DETERMINE  THE  DRY-SEASON  INFLOW  TO  LAKE 

NICARAGUA,  1899.— Continued. 


Date. 


Mar.    9. 


11. 
12. 
12. 
13. 
17. 
17. 
18. 
19. 
19. 
19. 
30, 
21. 
26. 
18. 


07 

Ml. 


April    4.» 


It 
ti 

(( 
11 

it 


7. 

8. 
11. 
13. 
15. 


Stream. 


Mollales 

Dilate 

Tepenaguasapa 

Frio 

Tule 

Zapote 

Haciendas  .... 

Pisote   

Oroci 

Mena 

Sabalo 

Sapoa  

Ocbomogo  .... 

Tipitapa 

Frio 

Frio 

Frio 

Malacatolla  . . . 

MollaleB 

Dilate 

Tepenagaasapa 
Tule 


Locality. 


Meter 
number. 


Telegraph  line 

Telegraph  line 

Inocente 

Santo  Tomas. . 


La  Mina 

St.  Emilio 

Pena  Blanca 

La  Vulcan 

Above  Falls 

4  miles  above  mouth. 

5  miles  above  mouth 
.5  miles  above  mouth , 
Tabacal 


Carraso^s  Ranch. 
Telegraph  line  . , 


c( 


t( 


93 

93 

«3 

1 

93 

93 

93 

93 

93 

93 

93 

93 

93 

93 

1 

1 

1 

93 


93 
93 


Gaffe 

height 

(ft). 


2.7 
1.1 
5.2 
0.2 
4.6 


1.2 
2.0 
1.8 
1.5 

•   •   •   • 

4.68 
5.75 
4.75 
4.32 
0.70 


0.80 
-.30 


Area  of 

sec.  (sq. 

ft). 


17.0 


133.5 
2913 
42.0 
107 
107 
77.4 
25.9 
43.5 
18.5 
95.3 
36.8 
734 
2320 
1690 
1788 
18 


115 
26 


Mean  ve- 
locity (ft. 
per  sec). 


1.27 

•   •   •   • 

0..52 
0.79 
0.81 
1.81 
1.10 
1.76 
1.43 
1.68 
1.68 
0.62 
1.46 
0.25 
0.79 
0.68 
0.74 
1.03 


0.45 
0.56 


DischarffQ 
(sec.-lt.). 


21.6 
00.0 
69.6 

2314 
84.1 
803 
118 
137 
37.0 
73.1 
31.1 
59.1 
53.9 
184.0 

1837 

1155 

1323 
18.6 
00.0 
00.0 
51.4 
14.6 


•Measurements  from  April  4  to  April  15,  inclusive,  were  made  by  Alfred  Ahrllng  and  R.  H.  Morrln. 


Kid  San  Juan. 

The  San  Juan  river  is  the  sole  outlet  of  Lake 
Nicaragua  and  its  tributary  drainage  basin.  Its 
total  length  from  the  lake  to  the  sea  is  122  miles 
and  it  is  usually  navigable  for  light-draught  river 
steamers.  It  leaves  the  lake  at  Fort  San  Carlos 
at  an  altitude  var^'ing  from  about  97  feet  to 
about  110.  Its  course  for  a  distance  of  27 
miles  is  through  a  low  swampy  country  relieved 
by  occasional  hills.  Through  this  course  the 
river  is  sluggish  and  receives  several  tributaries 
of  small  discharge,  which,  in  the  dry  season, 
are  practically  still  water.  The  principal  of 
these  are  the  Melchora,  Medio  Queso,  Palo  de 
Arco,  and  Kio  Negro.  The  first  tributary  of 
importance  to  the  San  Juan  river  is  the  Rio 
Sabalos,  which  enters  from  the  north  and 
empties    27    miles   east   of    Fort    San   Carlos. 


About  half  a  mile  below  the  mouth  of  the 
Sabalos  are  the  first  rapids,  called  Toro  rapids. 
These  rapids  are  caused  by  boulders  and  gravel, 
probably  brought  into  the  river  by  Rio  Sabalos 
in  former  times,  but  do  not  seriously  obstruct 
navigation  except  in  times  of  extremely  low 
water.  Below  this  point  the  San  Juan  receives 
the  waters  of  a  few  streams,  the  principal  of 
which  are  the  Rio  Poco  Sol  and  the  Rio  Santa 
Cruz.  Ten  miles  below  Toro  rapids  occur  the 
largest  rapids  on  the  river,  at  Castillo  Viejo. 
At  this  point  the  river  falls  about  5  feet  in  a  few 
hundred  feet,  and  steamers  are  seldom  taken 
over  the  rapids  except  in  high  water.  A  rail- 
road about  2000  feet  long  is  provided  for  the 
portage  of  freight  and  passengers  on  the  right 
bank  of  the  river. 

Below  Castillo  are  the  Diamond,  Balas  and 


218 


NICARAGUA   CANAL  COMMISSION 


Maclnica  rapids,  the  latter  being  12  miles  from 
Castillo.  All  of  these  rapids  admit  the  passage 
of  river  steamers  except  at  extreme  low  water. 
Below  Machiica  there  are  no  more  rapids.  The 
river  is  deep  and  sluggish  for  a  distance  of  about 
15  miles  to  the  point  where  it  receives  the  waters 
and  sediment  of  the  Rio  San  Carlos.  This  river 
is  the  largest  tributary  of  the  San  Juan,  rising 
far  to  the  southward  in  the  mountains  of  Costa 
Rica,  and  bearing  such  a  volume  of  sediment 
that  a  delta  has  been  built  up  at  its  mouth  and 
from  this  point  to  the  sea  the  San  Juan  is  a 
shallow  stream  with  sandy  shifting  bed.  Twenty- 
five  miles  farther  down  the  Sarapiqui  empties 
into  the  San  Juan  from  Costa  Rica,  being  the 
second  tributarv  in  size  to  the  San  Carlos,  and, 
like  the  latter,  bearing  large  quantities  of  sedi- 
ment in  times  of  flood.  Eight  miles  below  the 
mouth  of  the  Sarapiqui  the  San  Juan  assumes 
decidedly  the  character  of  a  deltaic  stream  and 
sends  out  a  small  distributary  known  as  the  San 
Juanillo,  which  meanders  through  the  swamps 
to  the  northward  and,  after  receiving  the  drain- 
age of  the  Deseado,  re-enters  the  San  Juan  4 
miles  above  its  mouth.  Five  miles  below  the 
exit  of  the  San  Juanillo  or  103  miles  from  Lake 
Nicaragua  the  main  stream  of  the  San  Juan 
separates  into  two  large  distributaries,  the 
larger,  called  the  Rio  Colorado,  flowing  eastv\-ard 
directly  to  the  Caribbean,  and  the  smaller,  or 
lower  San  Juan,  meandering  to  the  northeast 
and  finding  its  exit  into  the  ocean  at  Greytown. 
Between  the  mouth  of  the  Colorado  and  the 
lower  San  Juan  another  distributary,  called  the 
Rio  Taura,  finds  its  way  from  the  lower  San 
Juan  to  the  sea. 

The  principal  obstructions  to  free  navigation 
of  light-draught  river  craft  from  Greytown  to 
Fort  San  Carlos  consist  of  the  shoal  character 


of  the  lower  San  Juan,  especially  in  times  of  low 
water,  and  of  the  rapids  lying  between  Machuca 
and  the  mouth  of  the  Sabalos.  For  purposes  of 
a  ship  canal  the  river  also  required  deepening 
below  the  mouth  of  the  San  Carlos  and  between 
the  Sabalos  and  Fort  San  Carlos. 

The  only  portion  of  the  river  which  is  suit- 
able in  its  present  state  for  a  ship  canal  is  the 
part  from  !Machuca  to  a  point  a  short  distance 
above  Boca  San  Carlos,  or  about  15  miles  out  of 
122,  and  even  here  some  dredging  must  be  done 
and  two  sharp  bends  eliminated  to  permit  the 
safe  passage  of  the  largest  ships. 

Sabalos  Station  ox  San  Juan  River. 

The  San  Juan  river  is  not  well  adapted  in  the 
vicinity  of  Fort  San  Carlos  for  making  accurate 
measurements  at  all  stages,  the  banks  being  low 
and  swampy  and  subject  to  overflow  at  medium 
high  stages.  The  first  important  tributary^  en- 
tering the  river  is  Rio  Sabalos  which  empties  at 
the  steamboat  station  which  bears  the  same 
name.  This  is  about  half  a  mile  above 
Tore  rapids,  which  is  the  highest  point  at  which 
it  has  even  been  proposed  to  dam  the  river 
to  hold  the  lake  at  a  high  level.  A  gage  was 
placed  about  half  a  mile  above  the  mouth  of  the 
Sabalos  on  the  31st  dav  of  December,  1897.     It 

f  7 

consists  of  a  vertical  pine  board  driven  into  the 
river  bed  and  spiked  to  a  tree  growing  on  the 
bank.  The  elevation  of  the  zero  of  the  gage 
rod  is  90.85  feet  above  sea  level.  Measurements 
were  made  a  short  distance  above  the  gage  by 
means  of  a  boat  anchored  in  the  stream,  dis- 
tances being  measured  by  stretching  a  tagged 
rope  across  the  river.  The  discharge  at  this 
point  is  taken  as  being  essentially  the  outflow 
from  Lake  Nicaragua. 


APPENDIX   III.— HYDROGRAPHIC   REPORT 


219 


DAILY  GAGE  HEIGHT  OF  SAN  JUAN  RIVER  AT  STATION  SABALOS,  ^  MILE  ABOVE  TORO 

RAPIDS,  FOR  1898-9. 


1809. 

1808. 

Jan. 

Feb. 

Mar. 

Apr. 

May. 

June. 

July. 

Aug. 

Sep. 

Oct. 

Nov. 

Dec. 

Jan. 

Feb. 

Mar. 

Day. 
1 

9.98 

9.58 

9.13 

8.56 

8.20 

8.33 

9.55 

9.84 

9.92 

10.48 

10.85 

11.28 

10.82 

10.32 

9.90 

•> 

M  •     .    .    . 

9.88 

9.52 

9.10 

8.56 

8.14 

8.39 

9.58 

9.85 

9.92 

10.59 

10.80 

11.38 

10.79 

10.31 

9.90 

3.... 

9.84 

9.49 

9.10 

8.52 

8.14 

8.38 

10.28 

9.90 

9.92 

10.47 

10.80 

11.23 

10.70 

10.29 

9.85 

4 

9.80 

9.49 

9.10 

8.55 

8.14 

8.30 

10.22 

•  •   •   • 

9.91 

10.54 

10.75 

11.10 

10.71 

10.26 

9.85 

5 

9.80 

9.49 

9.04 

8.66 

8.08 

8.40 

9.90 

•   ■   •   • 

9.94 

10.53 

10.70 

11.00 

10.75 

10.22 

9.85 

6.... 

9.78 

9.49 

9.02 

8.67 

8.15 

8.41 

9.96 

•   •   •   • 

10.10 

10.50 

10.70 

10.96 

10.75 

10.27 

9.80 

7 

9.78 

9.49 

9.00 

8.58 

8.10 

8.38 

9.62 

9.93 

10.10 

10.49 

10.65 

11.01 

10.74 

10.27 

9.75 

8 

9.78 

9.48 

8.99 

8.55 

8.16 

8.40 

9.62 

9.86 

10.13 

10.54 

10.65 

10.96 

10.71 

10.25 

9.70 

5.... 

9.78 

9.46 

9.00 

8.44 

8.11 

8.38 

9.64 

9.76 

10.14 

10.56 

10.70 

10.89 

10.73 

10.21 

9.70 

10 

9.78 

9.41 

9.00 

8.46 

8.10 

8.42 

9.74 

9.96 

10.14 

10.51 

10.80 

11.23 

10.79 

10.21 

9.65 

11 

9.79 

9.39 

9.00 

8.48 

8.11 

8.38 

9.72 

9.92 

11.19 

10.45 

10.80 

11.25 

10.77 

10.22 

9.65 

12.... 

9.80 

9.42 

9.00 

8.48 

8.15 

8.41 

9.65 

9.90 

10.68 

10.40 

11.00 

11.03 

10.83 

10.26 

9.65 

13.... 

9.80 

9.42 

9.00 

8.52 

8.04 

8.42 

9.62 

9.90 

10.78 

10.42 

11.60 

10.99 

10.84 

10.20 

9.65 

14.... 

9.74 

9.41 

8.98 

8.48 

8.10 

8.31 

9.63 

10.43 

10.52 

10.42 

11.45 

10.90 

10.76 

10.07 

9.65 

15 

9.73 

9.38 

8.96 

8.46 

8.08 

8.36 

9.60 

10.20 

10.51 

10.44 

11.10 

10.84 

10.96 

10.09 

9.60 

1(> 

9.73 

9.36 

8.90 

8.46 

8.06 

8.39 

9.50 

10.10 

11.17 

10.48 

11.30 

10.94 

10.78 

10.09 

9.60 

17.... 

9.73 

9.34 

8.81 

8.44 

8.10 

8.39 

9.50 

9.92 

10.64 

10.58 

12.10 

11.23 

10.75 

10.12 

9.55 

18 

9.73 

9.32 

8.76 

8.39 

8.36 

8.50 

9.62 

9.90 

10.44 

10.89 

11.55 

11.11 

10.71 

10.19 

9.55 

19 

9.73 

9.29 

8.74 

8.:i2 

8.39 

9.52 

10.50 

9.88 

10.38 

10.78 

11.20 

10.98 

10.64 

10.11 

9.60 

20.... 

9.73 

9.27 

8.68 

8.34 

8.31 

9.34 

10.66 

9.86 

10.40 

11.25 

11.10 

10.89 

10.59 

10.11 

9.60 

21 

9.75 

9.27 

8.75 

8.32 

8.38 

9.60 

10.16 

9.85 

10.49 

10.84 

11.00 

10.83 

10.57 

10.08 

9.55 

22.... 

9.74 

9.26 

8.74 

8.30 

8.56 

9.46 

9.96 

9.86 

10.52 

10.72 

11.00 

10.80 

10.58 

10.04 

9.55 

23.... 

9.68 

9.24 

8.68 

8.30 

8.39 

9.26 

10.04 

9.83 

10.55 

10.76 

11.00 

10.78 

10.56 

10.01 

9..50 

24 

9.62 

9.22 

8.76 

8.33 

8.50 

9.61 

9.91 

9.83 

10.51 

10.68 

10.95 

10.72 

10.54 

10.00 

9.45 

25.... 

9.62 

9.20 

8.76 

8.28 

8.50 

9.70 

9.81 

9.83 

10.48 

10.78 

11.00 

10.70 

10.50 

9.97 

9.45 

26.... 

9.60 

9.18 

8.68 

8.28 

8.58 

9.48 

9.91 

9.84 

10.43 

10.90 

11.05 

10.68 

10.45 

9.98 

9.45 

27.... 

9.60 

9.15 

8.70 

8.26 

8.57 

9.50 

9.79 

9.85 

10.65 

10. 82 

11.10 

10.63 

10.47 

9.95 

9.40 

28 

9.60 

9.14 

8.67 

8.26 

8.50 

9.34 

10.14 

9.84 

10.84 

10.75 

11.35 

10.07 

10.43 

9.90 

9.40 

29 

9.60 

•   •   •   • 

8.62 

8.23 

8.45 

9.67 

9.96 

9.89 

10.55 

10.75 

11.45 

10.79 

10.41 

•   •   •   • 

9.4^ 

30.... 

9.60 

•   •   •    ■ 

8.62 

K.22 

8.46 

9.50 

10.64 

9.92 

10.55 

10.80 

11.10 

10.75 

10.39 

•   •    •   • 

9.35 

31.... 

9.60 

•    •    •   • 

8.55 

•  •   «   • 

8.43 

■   •   ■   • 

10.12 

9.92 

•   •    •    • 

10.85 

•    •   •   • 

10.81 

10.34 

•    •    •   • 

9.40 

LIST  OF  DISCHARGE  MEASUREMENTS  MADE  ON  SAN  JUAN  RIVER  AT  STATION  SABALOS. 


Date. 


Hydrogrrapher 


Meter 
numlK'r. 


Gage 
height 
(feet). 


Area  of 
8ection 
(8<ir.  ft.). 


Mean  ve- 
locity (ft. 
per  sec.). 


Disc*harge 
(second- 
feet). 


Remarks. 


1898. 

Jan.  21 R. 

C.  Wheeler 

Feb.     2 

tt 

»'      21 

(( 

»♦      25 

li 

Mar.     8 

t( 

8... 

11 

•»      16... 

(( 

»•      24... 

w 

.  M.  Barton 

•♦      31... 

14 

April   8... 

i( 

♦'       11... 

(t 

B.  &B.  1. 

9.75 

8,819 

2.16 

19,000 

Above 

Toro  rapids. 

6.30 

9,417 

1.85 

17,360 

Below  Toro  rapids. 

9.27 

8,576 

1.92 

16,530 

Above  Toro  rapids. 

9.20 

9,726 

1.64 

16,000 

Above 

previous  measurements 

9.10 

9,769 

1.58 

15,466 

Upper 

Station. 

9.00 

9,784 

1.51 

14,720 

8.tK) 

S),713 

1.48 

14,406 

3.70 

9,880 

1.43 

14,088 

8.60 

9,823 

1.35 

13,271 

8.60 

9,823 

1.30 

12,760 

8.50 

9,768 

1.30 

12,706 

220 


NICARAGUA  CANAL  COMMISSION 


LIST  OF  DISCHARGE  MEASUREMENTS  MADE  ON  SAN  JUAN  RIVER  AT  STATION  SABALOS.— 

Continued. 


Date. 

Hydrographer.               num^V 

Gage 
height 
(feet). 

Area  of 

section 

(sqr.  ft.). 

Mean  ve- 
locity (ft 
per  sec.) 

Dischaive 
.    rsecond- 

feet). 

Remarks. 

1898. 

April  19... 

.W.  M.  Barton 1 

8.40 

9,776 

1.27 

12,466 

Upper  Station. 

'*       25... 

8.80 

9,722 

1.22 

11,897 

tt 

"       29. . . 

8.20 

9,667 

1.22 

11,766 

tt 

May    10... 

8.10 

9,614 

1.20 

11,818 

it 

June    6... 

8.40 

9,776 

1.20 

11,706 

tt 

"       16... 

8.4C 

9,247 

1.23 

11,403 

tt 

"       20... 

.  .                                                                                    ^               ' 

9.30 

9,783 

1.40 

13,660 

tt 

'*       26... 

9.50 

9,829 

1.53 

15,025 

tt 

July   18... 

9.60 

9,876 

1.72 

17,020 

tt 

Sept.    5. . . . 

.W.  W.  Schlecht Stk.  1 

9.92 

10,674 

1.94 

20,666 

"       11   .. 

it                   ^  ^                 1 

11.29 

11,273 

1.95 

21,995 

Probably  back  water  by  Sabalos. 

»»       14... 

14                                            ^                                    1 

10.49 

10,684 

2.12 

22,678 

River  falling. 

"       21.... 

.R.  H.  Morrin 1 

10.48 

10,720 

2.09 

22,481 

River  -rising. 

Oct.    19... 

It                                     \ 

10.79 

11,190 

2.19 

24,520 

"       26... 

it           1 

10.90 

10,975 

2.18 

23,914 

Nov.     9. . . 

tt                                     1^ 

10.66 

10,864 

2.20 

23,965 

♦♦       17.... 

tt           1 

12.21 

11,816 

2.16 

25,550 

»*       28..., 

tt           \ 

10.99 

11,148 

2.25 

25,110 

Dec.      3... 

tt                                     j^ 

11.28 

11,273 

2.39 

26,700 

"       13.... 

it           \ 

10.99 

10,«72 

2.82 

25,500 

"       23..., 

tt           .....                 1 

10.78 

10,862 

2.28 

24,775 

1899. 

Jan.      2. . . . 

tt           1 

10.80 

10,936 

2. 13 

23,880 

"       14..., 

tt                                     1 

10.78 

10,979 

2.22 

24,880 

Feb.     2 

tt           \ 

10.81 

10,603 

2.05 

21,714 

"       15.... 

tt           1 

10.09 

10,208 

2.00 

20,870 

»»       23. . . . 

tt           \ 

10.01 

10,802 

2.02 

20,810 

Mar.     1 

8.   WilBon 1 

9.90 

10,145 

1.85 

18,770 

i«      14 

ft         ....       .                   1 

9.65 
9.47 

10,204 
10,010 

1.78 
1.76 

18,172 
17,576 

"      24 

it                   ....                 1 

RATING  TABLE  FOR  SAN  JUAN  RIVER  AT  STATION  SABALOS. 
This  table  is  applicable  only  from  January  1,  1898,  to  March  31,  1899. 


Gage 
height. 

Discharge. 

Gage 

hel^t. 

Discharge. 

heS^t. 

Discharge. 

Gage 
height. 

Discharge. 

Gage 
height. 

Discharge. 

Feet. 

Second-feet. 

Feet. 

Second-feet. 

Feet. 

Second-feet. 

Feet. 

Second-feet. 

Feet. 

Second-foot. 

8.0 

11,130 

8.8 

18,680 

9.6 

17,890 

10.4 

22,180 

11.2 

26,870 

8.1 

11,820 

8.9 

14,180 

9.7 

18,420 

10.5 

22,660 

11.8 

26,900 

8.2 

11,580 

9.0 

14,710 

9.8 

18,950 

10.6 

23,190 

11.4 

27,480 

8.8 

11,760 

9.1 

15,240 

9.9 

19,480 

10.7 

28,720 

11.5 

27,960 

8.4 

12,040 

9.2 

15,770 

10.0 

20,010 

10.8 

24,250 

11.6 

28,490 

8.5 

12,880 

9.8 

16,800 

10.1 

20,540 

10.9 

24,780 

11.7 

29,020 

8.6 

12,760 

9.4 

16,880 

10.2 

21,070 

11.0 

25,310 

11.8 

29,550 

8.7 

18,200 

9.5 

17,360 

10.3 

21,600 

11.1 

25,840 

11.9 

80,080 

APPENDIX   III.— HYDROGRAPHIC   REPORT 


221 


ESTIMATED  MONTHLY  DISCHARGE  OF  SAN  JUAN  RIVER  AT  STATION  SABALOS. 


Month. 


Discharge  in  Second- Feet.       Total  in 


Maximum.    Minimum.    Mean. '^*^"^^^®^ 


Month. 


Discharge  in  Second-Feet.       Total  In 
Maximum.    Minimum.    Mean.  Acre-Feet. 


1898. 

January 19,900 

February 17,780 

March 15,400 

April 18,070 

May 12,680 

June 18,420 

July 23,510 

August 22,290 

September . . .  26,210 


17,890 

18,590 

1,148,055 

15,480 

16,683 

923,750 

12,570 

14,045 

868,595 

11,580 

12,169 

724,105 

11,206 

11,763 

728,275 

11,760 

14,144 

841,625 

17,860 

19,369 

1,190,985 

19,110 

19,552 

1,202,200 

19,533 

22,075 

1,818,550 

8,926,090 


1898. 

October 26,630 

November  . . .  28,490 
December  . . .  27,820 

Total  for  1898. . . 


Brought  forward,  8,926,090 
22,180  23,430  1,440,650 
28,450  25,410  1,512,000 
24,000         25,050         1,540,260 

18,419,000 


1899. 

January 25,100 

February 21,720 

March 19,480 


21,810  23,470  1,448,120 
19,480  20,790  1,154,620 
16,560         17,950         1,108,700 


ELEVATION  OF  LAKE  NICARAGUA  IF  ALL  WATER  HAD  BEEN  HELD  BY  A  DAM  AT 

SABALOS,  1898-9. 


'     1898. 

Jan. 

Feb. 
105.11 

Mar. 

April. 

May. 

4 

June. 

Jul}'. 

Aug. 

Sept. 

Oct. 

Nov. 

Doc. 

Jan. 

Feb. 

Mar. 

Day. 

X  .  .  .  . 

104.94 

104.96 

104.57 

104.23 

104.79 

106.26 

107.94 

108.97 

110.37 

111.88 

112.90 

113.38 

113.64 

113.55 

2 

104.96 

105.06 

105.01 

104.59 

104.19 

104.81 

106.25 

107.91 

109.00 

110.47 

111.86 

112.92 

113.40 

113.66 

113.44 

8. . . . 

104.98 

105.18 

104.95 

104.57 

104.19 

104.77 

106.85 

107.93 

109.00 

110.52 

111.83 

112.91 

113.42 

118.64 

118.45 

4.... 

105.00 

105.15 

105.01 

104.56 

104.18 

104.78 

106.52 

108.02 

109.01 

110.52 

111.80 

113.00 

113.37 

118.63 

118.48 

5.... 

105.06 

105.20 

104.94 

104.53 

104.19 

104.78 

106.46 

108.07 

109.06 

110.55 

111.78 

118.04 

113.43 

113.68 

113.46 

6. . . . 

105.14 

105.14 

104.93 

104.59 

104.20 

104.82 

106.64 

108.05 

109.16 

110.56 

111.85 

118.02 

113.42 

113.66 

113.44 

7.... 

105.07 

105.16 

104.95 

104.56 

104.15 

104.90 

106.67 

108.10 

109.15 

110.60 

111.83 

113.07 

113.38 

113.66 

•  •  •  • 

8.... 

105.10 

105.18 

104.94 

104.51 

104.14 

104.88 

106.72 

108.22 

109.20 

110.66 

111.82 

113.01 

113.46 

118.65 

118.51 

(T   .     .     .     . 

105.06   105.19 

104.94 

104.49 

104.14 

104.89 

106.82 

108.21 

109.22 

110.63 

111.88 

113.03 

113.45 

113.63 

113.48 

10 

105.00 

105.10 

104.86 

104.44 

104.18 

104.91 

106.88 

108.21 

109.30 

110.66 

111.90 

113.09 

113.47 

118.63 

113.47 

11 

105.08 

105.10 

104.89 

104.50 

104.14 

104.92 

106.92 

108.28 

109.41 

110.66 

111.97 

113.11 

113.51 

113.69 

113.86 

12.... 

105.11 

105.18 

104.90 

104.51 

104.11 

104.99 

106.97 

108.20 

109.54 

110.73 

112.07 

118.11 

113.50 

113.78 

113.37 

13.... 

105.06 

105.^4 

104.90 

104.48 

104.04 

104.97 

106.98 

108.37 

109.72 

110.75 

112.22 

113.08 

113.51 

113.74 

113.33 

14.... 

105.04 

105.17 

104.83 

104.47 

104.12 

104.94 

107.00 

108.88 

109.75 

110.86 

112.21 

113.11 

113.48 

113.68 

118.36 

15.... 

105.05 

105.16 

104.89 

104.43 

104.07 

104.97 

107.07 

108.45 

109.80 

110.92 

112.29 

113.11 

113.57 

113.66 

113.37 

16.... 

105.11 

105.11 

104.82 

104.44 

104.16 

104.94 

107.18 

108.49 

109.88 

110.92 

112.3$ 

113.17 

113.52 

113.67 

113.42 

17.... 

105.13 

105.11 

104.77 

104.45 

104.13 

104.98 

107.12 

108.54 

109.96 

111.01 

112.38 

113.14 

113.55 

113.64 

113.36 

18.... 

105.19 

105.13 

104.71 

104.43 

104.26 

104.99 

107.17 

108.51 

109.97 

111.20 

112.48 

113.17 

118.62 

113.63 

113.36 

19.... 

105.22 

105.10 

104.64 

104.40 

104.24 

105.13 

107.22 

108.53 

109.99 

111.28 

112.44 

113.14 

118.64 

113.63 

113.26 

20. . . . 

105.37 

105.10 

104.69 

104.35 

104.27 

105.20 

107.39 

108.55 

110.02 

111.82 

112.40 

113.19 

113.69 

113.67 

113.84 

21.... 

105.82 

105.05 

104.74 

104.41 

104.32 

105.27 

107.83 

108.61 

110.11 

111.33 

112.60 

113.17 

113.63 

113.56 

113.32 

22.... 

105.25 

105.03 

104.56 

104.39 

104.62 

105.50 

107.43 

108.64 

110.20 

111.46 

112.58 

113.14 

113.62 

113.54 

113.25 

23.... 

105.18 

105.00 

104.70 

104.37 

104.60 

105.58 

107.43 

108.60 

110.17 

111.52 

112.60 

113.22 

113.57 

113.54 

113.29 

24.... 

105.11 

105.10 

104.74 

104.30 

104.72 

105.64 

107.54 

108.65 

110.28 

111.63 

112.62 

113.26 

113.56 

113.64 

113.28 

25.... 

105.20 

105.07 

104.76 

104.29 

104.80 

105.74 

107.57 

108.68 

110.28 

111.65 

112.64 

113.24 

113.63 

113.52 

118.22 

26.... 

105.21 

105.11 

104.46 

104.32 

104.79 

105.71 

107.61 

108.67 

110.26 

111.68 

112.66 

113.25 

113.63 

113.64 

113.22 

27 

105.22 

105.01 

104.68 

104.31 

104.85 

105.85 

107.67 

108.74 

110.24 

111.72 

112.74 

113  23 

113.60 

113.53 

113.16 

US.,,, 

105.22 

105.01 

104.62 

104.27 

104.88 

106.01 

107.76 

108.75 

110.38 

111.71 

112.80 

113.23 

113.60 

113.51 

113.19 

29.... 

105.09 

•  •   •   • 

104.60 

104.24 

104.74 

106.15 

107.70 

108.89 

110.42 

111.83 

112.84 

113.37 

113.63 

•    •   •   • 

113.20 

80.... 

105.22 

•   •  •   • 

104.63 

104.24 

104.84 

106.  yi 

107.88 

108.92 

110.43 

111.82 

112.93 

113.38 

113.62 

•   •   •    • 

113.28 

81.... 

105.17 

•   •   •   • 

104.51 

. .  *  • 

104.80 

.... 

107.87 

108.95 

•   •   ■   ■ 

11L82 

•    •   •   • 

113.48 

113.65 

•    ■   •   • 

118.21 

222 


NICARAGUA  CANAL  COMMISSION 


Rio  Sabalos. 

Occasional  measurements  of  the  Sabalos  river 

were  made  by  the  same  observer  employed  upon 

the  San  Juan  at  Sabalos.     A  gage  was  placed 

in  this  river  about  three  miles  above  its  mouth, 


but  at  certain  times  the  river  became  so  slug- 
gish at  this  point  as  to  be  difficult  to  measure. 
On  April  23  the  rod  was  moved  one  mile  farther 
up  the  stream.  The  following  measurements 
were  made  of  this  stream. 


LIST  OF  DISCHARGE  MEASUREMENTS  MADE  ON  RIO  SABALOS  1%  MILES  ABOVE  ITS  MOUTH. 


Date.             Hydrogrrapher. 

Meter          .^Jg®. 

Area  of 

section 

(sq.  feet). 

Mean  ve- 
locity (feet 

Discharge 
(second- 
feet). 

Remarks. 

1898. 

Jan.  24 R.  C.  Wheeler 

1                 6.00 

1,004 

0.29 

291 

Feb.  22 •*             

1                  5.60 

960 

0.16 

152 

Velocity  too  low  for  accuracy. 

"22 '*             

1                  5.60 

14^ 

0.96 

186 

Taken  1  mile  above  gage. 

Avlsira              ^  •     %     •     •                                                                                  •••• 

1                  5.41 

183 

0.99 

131 

•*     17 '♦              

1                  5.20 

105 

0.82 

86 

♦*     25 W.  M.  Barton 

1                  5.12 

108 

1.34 

145 

April   1 "             

1                  4.98 

81 

0.91 

74 

'»       9 •'             

1                  4.85 

88 

1.42 

125 

i(         A                             ti 

Vb«««                                                                                   •••• 

1                  4.80 

77 

1.09 

84 

♦*     23 »»             

1                  8.20 

71 

1.00 

71 

New  rod  8.20=4.70. 

»»     30 »'             

1                  8.10 

66 

1.11 

78 

May     6 »'             .... 

1                 3.07 

62 

1.05 

65 

"22.... 

1                  5.15 

444 

1.88 

812 

Not  the  regular  section. 

"27 "             

1                 3.50 

82 

1.38 

118 

June    4....             "             .... 

1                  8.31 

67 

1.24 

88 

It     11                     tt 

1                  3.70 

99 

2.56 

254 

CI           1g                                                tl 

1                  3.47 

69 

1.40 

97 

"27....             "              

1                  6.19 

595 

2.09 

1,246 

July    2 "             

1                  6.10 

618 

1.89 

1,158 

"     14                     " 

1                  5.15 

448 

1.50 

669 

Sept.    7 W.  W.  Schlecht. . . 

Stk.  1                 5.18 

426 

0.79 

338 

"     15 " 

1                 6.03 

596 

1.56 

928 

River  falling. 

"     23 R.  H.  Morrin 

1                  5.71 

568 

1.26 

719 

River  rising. 

Oct.  11 " 

1                  5.18 
1                  5.93 

476 
581 

0.44 
1.15 

213 
669 

"     27                      " 

Nov.  11....            " 

1                  5.81 

528 

1.09 

579 

"     15 " 

1                 6.49 

622 

1.62 

1,007 

"     22 " 

1                 5.92 

586 

0.95 

509 

"     29 " 

1                 7.70 

731 

2.49 

1,818 

Dec.     5 " 

1                 5.90 

552 

0.97 

588 

"     12 

1                 6.12 

572 

1.37 

783 

"     19 " 

1                 6.00 

545 

1.12 

612 

1899. 

Jan.   3 R.  H.  Morrin. 

1                 5.69 

510 

1.05 

585 

"     19.... 

1                  5.51 

467 

0.85 

896 

Feb.     4 " 

1                  4.98 

386 

0.28 

95 

"     14 " 

1                  4.81 

854 

0.86 

124 

"     21 

1                  4.85 

340 

0.53 

181 

"     25 " 

1                 4.68 

820 

0.24 

77 

Mar.    « 8.  Wilson. . . 

1                  4.55 
1                  4.80 
1                  4.13 

311 

110 

173 

0.24 
0.90 
0.42 

76 

100 

76 

3  miles  above  mouth. 

"     21 ... .          " 

4      it         i(             (i 

"     31....          "         .... 

3      (»         li             u 

APPENDIX   III.— HYDROGRAPHIC   REPORT 


223 


Castillo  Station  on  San  Juan  River. 

Two  gages  were  placed  in  the  San  Juan 
river  at  Castillo,  one  above  the  falls  and  one 
below.  The  upper  gage  was  fastened  to  the 
downstream  support  of  the  first  building  below 
the  steamboat  wharf  above  the  rapids.  The 
lower  gage  was  fastened  to  the  northeast  corner 


of  the  wharf  at  the  lower  Bodega  below  the 
rapids.  The  zero  of  the  upper  gage  is  5.65  feet 
above  the  zero  of  the  lower.  Mr.  John  S. 
Augustine,  the  agent  at  Castillo,  was  employed 
to  read  the  gages,  daily  readings  being  taken  of 
both.     He  also  kept  a  record  of  rainfall. 


DAILY  GAGE  HEIGHT  OF  SAN  JUAN  RIVER    AT  CASTILLO  ABOVE  FALLS   FOR  1898-9. 


1 

1899. 

1896. 

Jan. 

Feb. 
3.10 

Mar. 

Apr. 

May. 

June. 

July. 

Aug. 

Sep. 

Oct, 

Nov. 

Dec. 

Jan. 

Feb. 

Mar. 

Day. 
1 

•   •   •   • 

2.60 

•    •   •    • 

2.00 

2.20 

4.00 

3.60 

3.20 

3.75 

3.90 

4.50 

3.80 

3.50 

8.10 

2.... 

•   •   •   • 

3.10 

•   «    •   • 

•   •   •   • 

2.00 

2.20 

3.80 

3.50 

8.20 

4.10 

3.90 

4.65 

3.80 

8.50 

3.10 

t$  •  •  •  • 

•   •   •   • 

•   •   •   • 

•   •   *   * 

•   •   •   • 

1.95 

2.20 

5.50 

8.60 

3.20 

4.00 

3.90 

4.40 

8.80 

8.50 

8.10 

4.... 

•    •   •   • 

•   •   •    • 

•   •   •    • 

2.20 

1.95 

2.00 

4.60 

3.45 

3.20 

4.00 

3.80 

4.30 

3.90 

3.50 

3.00 

o  •  •  •  • 

•   *   •   • 

•   •   •   • 

•   •   •    • 

2.50 

1.95 

2.00 

4.30 

3.55 

3.25 

4.00 

3.80 

4.10 

4.00 

8.40 

3.00 

0. . . . 

•   •   •   • 

3.15 

•   •   •  • 

2.85 

1.95 

1.90 

3.80 

3.80 

3.30 

4.00 

3.70 

4.10 

4.30 

8.40 

8.00 

7.... 

•   ■   •   • 

•   •  •    • 

2.50 

2.65 

1.95 

1.90 

3.60 

3.60 

3.80 

•   •   •   • 

3.70 

4.10 

4.20 

8.40 

3.00 

o  •  •  .  • 

•   •   •   « 

3.10 

2.40 

2.60 

1.90 

2.00 

3.60 

3.50 

3.10 

•   •   •   • 

3.70 

4.10 

4.20 

3.30 

8.00 

«'•••• 

.... 

•    •   •    « 

2.60 

1.90 

2.35 

3.80 

3.50 

3.20 

3.80 

3.60 

4.20 

4.90 

8.30 

2.90 

10 

•   •   •   • 

•    •   •    • 

2.40 

1.90 

2.35 

8.75 

3.50 

3.45 

3.80 

3.90 

4.20 

4.30 

8.80 

2.90 

11.... 

•  •   •   t 

•    •    •    • 

2.40 

2.06 

2.35 

3.70 

3.45 

5.80 

8.70 

8.90 

4.30 

4.10 

3.30 

2.90 

12 

3.20 

•    •    •    • 

2.30 

2.03 

2.35 

3.60 

3.60 

4.30 

3.70 

4.10 

4.30 

5.00 

3.50 

2.90 

13 

3.20 

•    •   ■   • 

2.27 

2.00 

2.30 

3.75 

3.40 

4.45 

3.70 

5.80 

4.15 

5.00 

8.50 

2.90 

14.... 

3.20 

2.90 

• 

2.25 

2.00 

2.20 

3.60 

4.60 

4.00 

3.70 

4.80 

4.10 

4.80 

8.50 

2.90 

15.... 

3.20 

2.90 

2.20 

2.00 

2.25 

3.60 

4.00 

4.00 

3.70 

4.30 

4.00 

4.20 

3.50 

2.90 

16.... 

3.30 

■   •   •    • 

2.15 

2.00 

2.30 

3.45 

3.65 

5.40 

3.70 

4.30 

4.00 

4.00 

3.40 

3.80 

17 

3.30 

2.87 

2.40 

2.15 

2.00 

2.20 

3.40 

3.60 

4.30 

8.75 

6.20 

4.90 

4.10 

8.30 

3.80 

18.... 

3.30 

•   •   •   • 

2.15 

2.00 

2.20 

3.50 

3.40 

4.20 

8.80 

5.00 

4.50 

4.00 

3.30 

8.80 

10.... 

3.30 

2.85 

2.15 

2.50 

4.10 

4.30 

3.30 

4.00 

4.80 

4.70 

4.10 

3.80 

3.80 

2.80 

20.... 

3.30 

•   •   •   • 

2.05 

2.40 

4.15 

4.00 

3.30 

3.95 

4.60 

4.60 

4.00 

3.80 

3.20 

2.90 

21.... 

3.30 

•   •   •    • 

2.10* 

2.25 

4.45 

4.05 

3.30 

3.95 

4.60 

4.50 

4.00 

8.70 

3.20 

2.90 

22.... 

3.30 

•    •   •   • 

2.05 

2.60 

4.30 

4.00 

3.30 

3.90 

4.10 

4.50 

3.85 

3.70 

3.20 

2.90 

23.... 

3.20 

•   •    •    • 

•   •   •   • 

2.45 

3.40 

3.90 

3.30 

4.35 

4.10 

4.30 

8.85 

3.70 

3.30 

2.90 

24.... 

•   •   •   • 

•    •   ■   • 

•    •   •   • 

2.35 

4.90 

3.60 

3.30 

4.00 

4.10 

4.20 

8.80 

3.80 

3.30 

2.90 

25. . . . 

•    •   •    • 

•    •   •    • 

•    •   •   • 

2.30 

4.50 

3.60 

3.30 

3.95 

4.10 

4.20 

3.70 

8.80 

3.30 

2.90 

26.... 

3.20 

• 

.... 

•   •   •   • 

•    •   •    • 

2.35 

3.70 

3.70 

3.30 

4.00 

4.40 

4.20 

3.70 

3.80 

3.80 

2.80 

27.... 

3.20 

•    •    •    • 

2.40 

2.00 

2.35 

3.65 

3.55 

3.80 

4.00 

4.00 

4.20 

8.90 

8.80 

3.30 

2.80 

28.... 

3.10 

2.70 

2.40 

•    •   •    • 

2.35 

3.50 

4.30 

8.20 

•   •  •   • 

4.00 

4.80 

3.80 

3.70 

8.00 

2.80 

29.... 

3.10 

•    •    •   • 

•    •    •    • 

•    •   •   • 

2.20 

4.10 

4.20 

8.20 

3.90 

3.90 

4.80 

4.00 

8.70 

•   •   •   • 

2.80 

30 

3.10 

•   •   •   • 

•    •    •    • 

2.00 

2.20 

3.70 

4.00 

3.15 

3.85 

8.90 

4.40 

•   •   •    • 

3.70 

•   «   •   • 

2.80 

81 

3.10 

•   •    •    • 

•    •   •    • 

•    •   •   • 

2.20 

•    •    •    • 

4.00 

3.15 

•    •   •   • 

3.90 

•       •    • 

•   •   •   • 

8..50 

•   •   •    • 

2.80 

224 


NICARAGUA  CANAL  COMMISSION 


DAILY  GAGE  HEIGHT  OF  SAN  JUAN  RIVER  AT  CASTILLO  BELOW  FALLS  FOR  1898. 


1898. 

Jan. 

Feb. 

Mar.. 

April. 

May. 

June. 

July. 

Aug*. 

Sept. 

Oct. 

Nov. 

Dec. 

1899. 
Jan. 

Feb. 

Mar. 

Day. 

3.80 
3.80 
3.80 
3.80 
3.90 

3.90 
.1.80 
3.80 
3.80 
3.70 

3.60 
3.60 
3.40 
3.50 

3.20 
3.10 

2.45 

2.10 
2.10 
2.00 
2.00 
2.00 

2.00 
2.00 
1.75 
1.75 
1.75 

1.75 
3.03 
3.00 
1.90 
1.90 

1.90 
1.90 
2.00 
2.50 
2.80 

2.50 
2.80 
2.60 
2.55 
2.55 

2.55 
2.55 
2.55 
2.45 
2.40 
2.40 

2.40 
2.40 
2.40 
2.26 
2.20 

2.10 
2.10 
2.10 
2.70 
2.70 

2.75 
2.70 
2.60 
2.40 
2.45 

2.50 
2.40 
2.40 
5.55 
5.50 

6.10 
5.00 
4.40 
5.75 
6.28 

4.95 
4.05 
4.30 
5.10 

4.82 

4.82 
5.65 
6.00 
6.10 
5.50 

5.00 
4.80 
4.65 
6.00 
4.  IK) 

4.90 
4.00 
4.80 
4.60 
4.50 

4.30 
4.40 
4.40 
5.65 
5.50 

5.65 
5.40 
5.00 
4.80 
4.60 

4.80 
4.40 
5.85 
6.60 
6.50 
6.00 

4.40 
4.30 
4.60 
4.50 
4.50 

4.90 
4.60 
4.50 
4.30 
4.30 

4.30 
4.40 
4.20 
5.55 
5.00 

4.80 
4.60 
4.40 
4.30 
4.30 

4.00 
4.20 
4.20 
4.10 
4.15 

4.05 
4.05 
4.05 
4.00 
4.00 
4.00 

4.10 
4.10 
4.10 
4.15 
4.25 

4.60 
4.50 
4.00 
4.45 
4.50 

5.60' 
6.10 
5.50 
5.80 

5.58 
5.50 
5.30 
5.30 

5.45 
5.40 
6.00 
5.40 
5.20 

5.30 
5.30 

"5.26* 
5.00 

4.90 
5.50 
5.20 
5.20 
5.10 

6.10 

5.00 
4.80 

4.70 
4.60 
4.60 
4.70 
4.70 

4.70 
4.80 
6.00 
over-all 
6.50 

6.10 
5.60 
5.60 
5.60 
5.60 

5.90 
5.40 
5.40 
5.40 
5.40 
5.40 

5.40 
6.40 
6.40 
6.80 
5.00 

5.00 
5.00 
6.00 
4.90 
6.10 

5.10 
5.60 
over-all 
6.60 
5.90 

6.00 

over-all 

over-all 

6.35 

6.30 

6.20 
6.10 
6.90 
6.70 
5.60 

5.60 
6.65 
6.70 
6.70 
5.60 

6.30 
6.50 
6.00 
5.80 
5.50 

6.30 
5.30 
5.30 
5.40 
6.40 

5.60 
6.60 
5.40 
5.30 
5.10 

5.10 
6.80 
6.30 
5.46 
6.20 

6.10 
5.05 
6.00 
5.00 
4.90 

4.90 
5.05 
6.05 
6.30 

5.00 
5.00 
5.00 
5.15 
5.25 

5.45 
5.30 
5.80 
5.60 
5.60 

5.45 
6.85 
6.30 
6.20 
6.85 

6.00 
5.40 
5.«5 
5.00 
5.00 

4.20 
4.25 
4.85 
4.80 
4.80 

4.80 
4.80 
4.76 
4.75 
4.70 
4.50 

4.60 
4.50 
4.50 
4.50 
4.40 

4.40 
4.40 
4.35 
4.35 
4.82 

4.82 
4.42 
4.60 
4.60 
4.60 

4.40 
4.36 
4.30 
4.25 
4.20 

4.20 
4.20 
4.20 
4.80 
4.80 

4.80 
4.26 
4.00 

•   •  •    .  •   • 

8.90 

«6.    •    •   • 

O  ■  •  •  • 

3.90 
3.90 

4 

8.80 

O  •  •  •  • 

'*3*.66 

3.35 

3.50 
3.10 
3.00 
2.80 

3.80 

6 

7.... 

3.80 
8.80 
3.70 

y.... 
10 

8.70 
3.70 

11 

3.70 

12 

13 

14 

15 

4.40 
4.40 
4.10 
4.10 

4.00 
3.90 
4.00 
4.10 
4.00 

4.20 
4.30 
4.10 
4.00 
3.90 

8.90 
4.20 
4.00 
4.00 
3.90 
3.90 

2.95 
2.90 

2.70 
2.60 
2.50 
2.45 

2.35 
2.30 

8.70 
8.70 
3.70 
8.70 

16 

8.60 

17.... 

1« 

1».... 
20 

3.40 
3.35 

2.85 
2.80 

3.62 
8.50 
8.50 
3.50 

21 

3.30 

3.50 

22 

2.25 

3.60 

23.... 
24 

2.75 

3.50 
3.50 

25 

3.40 

26 

3.40 

27.... 
28 

3.20 

2.70 

2.20 

3.40 
3.45 

29. . . . 
30.... 
31.... 

2.65 
2.60 
2.60 

2.10 ' 

3.40 
8.40 
3.40 

ESTIMATED  MONTHLY  DISCHARGE  OF  SAN  JUAN  RIVER  ABOVE  THE  MOUTH  OF  THE 

SAN  CARLOS. 

This  is  obtained  by  subtracting  the  discharge  of  the  San  Carlos  from  that  of  the  San  Juan  at  Ochoa. 


Month. 


Discharge  in  Second-Feet.       Total  In 


Maximum.    Minimum.    Mean. '^*^'^^^®*- 


Month. 


Discharge  in  Second-Feet.       Total  In 
Maximum.    Minimum.    Meain.  ^^*^^®®*^- 


1898. 

January  (10-81)  23,270  19,500  21,030 

February 34,000  18,500  22,080 

March 22,000  14,600  16,850 

April    25,800  12,900  15,120 

May    19,200  11,700  14,180 

June 39,200  13,000  22,410 

July 43,100  26,200  82,720 

August 38,400  23,000  26,170 

September 41,800  22,800  29,210 


917,650 
1,226,260 
1,036,070 
899,700 
868,820 
1,383,600 
2,011,870 
1,609,130 
1,738,120 


1898.  Brought  forward,  11,641,120 

October 37,600  24,700         29,820       1,802,820 

November 70,500  26,800        86,460       2,169,.520 

December 41,800  26,800        81,670       1,941,160 

Total 17,554,620 

1899. 

January 38,900  26,300         31,800       1,955,300 

February 28,200  23,100         25,180       1,398,430 

March 23,100  19,600         21,540       1,324,460 


11,641,120 


APPENDIX   III— HYDROGRAPHIC   REPORT 


ESTIMATED  MONTHLY  DISCHARGE  OF  TRIBUTARIES  TO  SAN  JUAN  RIVER  BETWEEN 

SABALOS  AND  SAN  CARLOS  RIVERS. 

Tbls  Is  the  difference  between  tbe  discharge  ot  the  Saa  Juan  above  Boca  Sap  Carlos  and  at  Sabalos. 

DraloBge  area  T50  equare  miles,  approilmatcly. 


Monti. 

«»nd-Ccot. 

Total  In 
Acre-feat. 

Ru 

-on. 

Maximum.         Mlnlmu 

m.               Mean. 

^SSf.i" 

Seooncl-f^el 
per  sq.  mile. 

January  (10-31) —  5,100 

Febraar; 17,600 

Mtrcb 8,800 

April 12,700 

May 7,000 

June 21,000 

Jnly 21,600 

AoKiiat 18,100 

September IS.OOO 

October 11,900 

November 4B,000 

December 15,800 

Total  1898 .\.. 


1890. 

Jannaiy 14,<00 

Tebrnary 7,100 

March 4,400 


8,400 
3,600 
3,000 
3,  BOO 


176,180 

146,340 

4.40 
8.86 

3.95 
8.17 

492,100 

13.31 

11.03 

830,860 

30.53 

17.80 

404,SBO 

laii 

8.77 

434,860 

10.63 

9.53 

878,000 

9.80 

8.07 

659,360 

16.47 

14.78 

402,  ISO 

10.05 

8.73 

,490,340 

513,180 

13.80 

11.10 

348,810 

6.09 

5.85 

1 

"™       "to     ""o"     ""o       tQM       io"       ^DJO       ^^%      ^0?D       °"o       To     i       °oli 

\       ■    '       \           !    1 

^                                          ^t         _l[.__^____         

I                                                                1         ^I     ±                — 

1         ^      _     ^_         __. 

Z'"  ^           ^l||]^__^ 

I                                            11       'L       ,^         L    . 

J  ^        

Z"]            -Jl^4i-1-     - 

i               ■■ .  Ill  1 

uriiup  ^1'  ' 

FiQ.  4.    Diagram  of  dally  discharge  of  tributaries  of  San  Juan  between  Sabalos  and  Boca  San  Carlos,  IS98. 


NICARAGUA  CANAL  COMMISSION 


;|||| 


Fio.  6.    Diagram  ot  dally  discharge  o(  the  San  Juan  above  Boca  San  Carlos. 


Eio  San  Carlos. 
The  San  Carlos  river  is  a  wide,  swift  stream, 
heading  in  the  high  mountains  of  Costa  Rica. 
From  these  mountains  it  obtains  large  quantities 
of  volcanic  sand,  portions  of  which  become 
ground  &ae  enough  to  be  held  in  suspension,  and 
large  quantities  are  carried  both  in  this  way  and 
rolled  on  the  bottom  of  the  stream,  especially 
in  times  of  great  floods  to  whicli  this  river  is 
subject.  Ita  drainage  area  as  measured  from 
the  best  maps  obtainable  is  1450  square  miles, 
but  this  must  be  regarded  as  merely  a  rough 
approximation,  as  the  country  has  never  been 
even  thoroughly  explored,  much  less  accurately 
mapped.  Above  the  mouth  of  the  San  Carlos 
the  San  Juan  is  a  stream  of  comparatively  uni- 
form discharge,  the  greater  portion  of  its  water 
coming  from  Lake  ^Nicaragua,  which  acta  aa  a 
very  effective  regulator  upon  the  floods  in  the 
basin.  From  the  mouth  of  San  Carlos  river  to 
the  foot  of  ilachuca  rapids  the  San  Juan  is  very 
deep   and   the   current   consequently   sluggish. 


This  portion  is  called  the  Aguas  Muertas,  or 
dead  waters.  It  frequently  occurs  that  the  San 
Carlos  is  in  flood,  and  the  large  volume  of  water 
affects  the  water  surface  of  the  Aguas  Muertas, 
in  proof  of  which  a  rise  in  the  San  Juan  below 
!Machuca  rapids  has  been  observed,  amounting 
to  nearly  four  feet  at  a  time  when  the  San  Carlos 
was  in  flood,  while  no  rise  whatever  occurred 
above  the  rapids.  The  largo  quantity  of  mate- 
rial carried  by  the  San  Carlos  river  has  built  a 
delta  at  its  mouth  so  that  it  flows  to  the  San 
Juan  through  two  channels  around  a  deltaic 
island,  and  from  its  mouth  to  the  sea  the  bottom 
of  the  San  Juan  is  covered  with  moving  sands 
brought  in  by  the  San  Carlos. 

Slalion  on  Rio  San  Carlos. — A  station  was 
established  on  the  San  Carlos  river  about  three 
miles  above  its  mouth,  on  the  10th  day  of  Jan- 
uary', 1898.  The  gage  consists  of  a  pine  board 
painted  white  and  graduated  to  feet  and  tenths 
from  zero  to  15  feet,  the  reading  being  con- 
tinued on  another  board  fastened  to  another  tree 


APPENDIX  III.— HTDROORAPHIC  REPORT 


227 


a  short  diBtance  downstream  and  higher  up  on 
the  bank.  A  f-inch  steel  cable  was  placed  across 
the  river  at  this  point,  npon  which  traveled  a 
gaging  oar  from  which  measurements  were  made. 


cord  was  fastened,  and  the  other  end  attached  to 

the  meter  cord  JHst  above  the  meter.     This  held 

the  instrument  from  drifting  downstream,  and 

heavy  lead  sinker  would  carry  it  to  any  de- 


In  times  of  high  water  the  stream  is  so  swift     sired  depth,  where  it  could  he  held  without 
that  it  is  difficult  to  make  the  meter  sink  to  the     difficulty.     This  arrangement   ia  illustrated  in 


Plate  VII.    Starting  to  gage  a  river. 


desired  point  in  the  stream,  the  tendency  of  the 
meter,  in  spite  of  heavy  lead  weights,  being  to 
drift  downstream  and  rise  to  the  surface,  under 
the  joint  influence  of  the  current  and  the  sus- 
pending wire.  To  overcome  this  difficulty 
another  and  smaller  cable  was  thrown  across  the 
river  about  200  feet  above  the  main  cable,  which 
carried  a  small  pulley  block.     To  this  pulley  a 


Plate  Vm.  A  sediment  trap  was  also  em- 
ployed at  this  station,  suspended  from  the  cable 
when  in  operation. 

A  bench  mark  was  made  by  driving  a  spike 
into  a  large  root  of  the  tree  used  as  a  cable  sup- 
port, which  stood  out  from  the  tree  like  an 
abutment  The  bench  mark  is  30.74  feet  above 
zero  of  the  gage.     The  high   water  occurring 


228 


NICARAGUA  CANAL  COMMISSION 


from  the  2d  to  the  Sth  of  January  scoured  out 
the  channel  of  the  river  somewhat,  so  that  a  sep- 
arate rating  table  has  been  made  for  January 
and  another  for  the  months,  February,  March, 


April  and  May;  still  another,  somewhat  different, 
is  used  from  the  1st  of  June  for  the  balance  of 
the  season. 


DAILY  GAGE  HEIGHT  OF  SAN  CARLOS  RIVER  THREE  MILES  ABOVE  ITS  MOUTH  FOR  1898-9. 

1898. 

Jan. 

Feb. 

Mar. 

Apr. 

May. 

June. 

July. 

AufiT. 

Sep. 

Oct. 

Nov. 

Dec. 

1809. 
Jan. 

Feb. 

■ 

Mar. 

Day. 

•    •   •   • 

12.79 

12.35 

11.47 

11.03 

12.88 

15.30 

13.01 

13.00 

13.00 

14.20 

13.85 

11.90 

11.85 

12.40 

2.... 

•   •   •   • 

16.21 

12.83 

11.45 

11.19 

12.30 

15.93 

13.80 

13.16 

13.15 

13.80 

13.65 

12.75 

11.85 

12.20 

o .   .   .   . 

•    •   •   • 

16.06 

12.58 

11.45 

11.03 

11.88 

15.31 

14.90 

12.90 

12.80 

13.50 

14.05 

14.35 

11.80 

12.15 

4 

•   •   •   • 

17.41 

12.37 

11.43 

11.05 

11.68 

14.92 

14.05 

13.05 

12.75 

13.90 

13.75 

12.80 

11.70 

12.05 

Q  •  .  •  • 

•   •   •   • 

19.23 

13.82 

12.93 

11.05 

11.58 

16.10 

14.87 

13.15 

12.75 

13.45 

13.65 

12.60 

11.65 

12.00 

6.... 

*    *    •    a 

18.26 

13.43 

18.15 

11.08 

11.50 

14.97 

14.74 

13.15 

13.95 

13.35 

13.95 

12.40 

11.60 

11.85 

7 

•    •    •    • 

16.20 

12.73 

13.29 

11.03 

12.25 

15.18 

13.94 

12.85 

13.25 

14.00 

13.50 

12.15 

12.05 

11.85 

0  • . . . 

•    •    •    • 

15.92 

12.43 

13.00 

11.01 

11.98 

16.78 

13.58 

12.60 

13.10 

14.90 

13.30 

12.55 

12.00 

12.70 

«7  .    .    .    a 

•    •    •    • 

15.20 

12.33 

13.00 

11.00 

11.75 

18.11 

13.30 

12.45 

13.35 

16.05 

13.10 

12.50 

11.70 

12.80 

10.... 

16.00 

14.60 

12.43 

12.35 

11.01 

12.80 

19.53 

13.14 

12.48 

13.30 

16.50 

13.70 

12.35 

11.70 

12.20 

11 

15.40 

14.27 

12.40 

12.00 

11.02 

12.28 

17.13 

13.40 

13.10 

• 

13.30 

15.35 

16.75 

12.20 

11.70 

11.95 

12.... 

15.00 

13.95 

12.22 

12.05 

11.04 

11.95 

15.68 

13.52 

12.55 

13.80 

14.85 

15.05 

12.35 

11.70 

11.80 

13.... 

14.62 

18.76 

12.^8 

11.98 

11.04 

11.85 

15.25 

14.65 

14.25 

13.60 

19.10 

14.35 

13.00 

12.70 

11.75 

14... 

14.85 

13.47 

11.97 

11.86 

11.12 

12.97 

14.85 

15.51 

14.50 

13.75 

18.05 

13.95 

13.25 

14.70 

11.80 

15.... 

14.07 

13.39 

11.87 

11.71 

11.13 

12.60 

14.45 

14.38 

13.75 

13.30 

16.70 

13.55 

12.90 

13.45 

11.70 

16.... 

14.07 

13.15 

11.95 

11.60 

11.64 

13.19 

14.59 

14.09 

14.50 

14.15 

16.55 

13.35 

15.00 

13.25 

11.65 

17 

14.25 

12.95 

11.95 

11.46 

11.76 

13.49 

14.20 

13  65 

14.40 

13.75 

20.20 

13.30 

13.60 

12.70 

11.55 

18 

18.87 

12.80 

12.53 

11.48 

11.88 

13.11 

14.10 

13.42 

13.85 

16.40 

17.60 

13.15 

13.25 

12.85 

11.50 

19 

13.65 

12.85 

11.89 

11.60 

12.05 

13.78 

14.18 

13.23 

13.75 

16.90 

16.40 

13.90 

13.20 

12.95 

il.50 

20.... 

13.47 

12.71 

11.74 

11.51 

13.50 

14.38 

14.25 

13.45 

14.90 

16.10 

15.50 

12.75 

13.20 

12.85 

11.40 

21 

13.65 

12.61 

11.69* 

11.41 

12.55 

14.29 

14.12 

13.50 

13.95 

14.90 

15.05 

12.60 

12.85 

13.30 

11.40 

lit-t  .... 

13.47 

12.54 

11.66 

11.29 

12.54 

13.74 

13.81 

14.58 

14.30 

14.35 

14.70 

12.50 

12.65 

12.85 

11.30 

23.... 

13.27 

12.52 

11.65 

11.40 

12.18 

13.90 

13.69 

13.86 

15.00 

14.30 

14.30 

12.40 

12.55 

13.70 

11.25 

24 ... . 

13.05 

12.36 

11.56 

11.48 

12.09 

15.98 

13.33 

13.93 

13.80 

16.30 

14.00 

12.20 

12.50 

13.20 

11.20 

25 ... . 

12.88 

12.45 

11.68 

11.41 

11.93 

15.20 

13.21 

13.70 

13.70 

15.15 

13.90 

12.20 

12.60 

12.90 

11.15 

26 

12.77 

12.45 

12.19 

11.31 

11.74 

15.15 

13.12 

13.60 

13.50 

19.30 

13.85 

12.20 

12.35 

12.55 

11.10 

27 

12.81 

13.05 

12.69 

11.84 

11.55 

17.70 

12.98 

13.90 

14.05 

16.15 

13.65 

12.20 

12.20 

12.80 

11.10 

28.... 

13.68 

13.00 

12.44 

11.33 

11.90 

18.53 

12.84 

13.80 

13.95 

15.25 

13.90 

12.10 

12.15 

12.60 

11.05 

29.... 

13.17 

•  •   •   • 

11.98 

11.13 

12.00 

16.92 

14.14 

13.35 

13.50 

14.85 

14.00 

12.00 

12.05 

•   •   •   • 

11.10 

30.... 

13.02 

•    •   •   • 

11.74 

11.05 

11  85 

15.53 

13.50 

13.00 

13.30 

14.40 

14.65 

11.95 

12.00 

•   •   •   • 

11.10 

31 

12.80 

• 

•   •   •    • 

11.03 

•   •   •   • 

12.60 

•   •   •   • 

18.08 

13.10 

.... 

15.05 

•   •   •   • 

11.95 

11.90 

•   •   •   • 

11.05 

LIST  OF  DISCHARGE  MEASUREMENTS  MADE  ON  SAN  CARLOS  RIVER  THREE  MILES 

ABOVE  ITS  MOUTH. 


Date. 


Hydrogrraphcr. 


Meter 
number. 


Gage  Area  of  Mean  ni«oh«ra« 

height         section  velocity         .li?.  f**^ 

(ft).  (sq.ft.).      (ft.  per  sec),     ^sec.-rt,). 


licmarks. 


1898. 

Jan.  27 R.  Breese 

"     29 *» 

'»     31 " 

Feb.   2 *' 

((      4 '* 

'«       5 " 

"     10 »' 

*'     11 " 


65 
65 
65 
65 
65 
65 
65 
65 


12.63 
13.17 
12.75 
16.37 
17.87 
19.00 
14.59 
14.19 


2,897 
3,529 
8,076 
5,509 
6,503 

4,880 
3,642 


3.26 
3.57 
3.37 
4.00 
4.27 

•   •   •  • 

4.59 
3.34 


9,445 
12,602 
10,352 
22,208 
27,782 

14, 890 
12,201 


Rising. 

Rising  rapidly. 
Battery  failed. 


APPENDIX  III.— HYDEOORAPHIC  REPORT 


UST  OF  DISCHARGE  MEASUREMENTS  MADE  ON  SAN  CARLOS  RIVER  THREE  MILES 
ABOVE  ITS  MOUTH.—Contlnued. 


». 


April   6 

31 

M.J 

13 

14 

,. 

W... .'.'.'.'. 

.Innfl 

20 

23 

24 

37 

39 

30 

July    4 

8 

10 

13 

33 

28 

30 

Aat! 

2 

8 

6 

14 

33 

28 

8«P-  B 

10 

14 

23 

Oct 

4 

., 

20 

Not 

U 

1» 

38 

Mfc 

IS 

19 

27 

SI 

IBM. 

.Tin 

2 

S 

13 

16 

81 

Feb 

8 

18 

14 

30 

MAr 

1 

9 

17 

20 

34 

'• 

89 

R.  C.  Wheeler 


13.10 
11.40 

11.03 


1,990 

3,5S7 
8,t»40 

8,360 
5,503 
7,837 
6,001 


15.48 

4,761 

13.88 

8,530 

13,20 

3,036 

13.58 

8,810 

13.04 

15.70 

4,873 

15.20 

4,409 

15.37 

4,544 

15.93 

6,114 

14.50 

3,933 

18.89 

3,579 

13.60 

3,781 

13.48 

14.47 

4,039 

14.32 

3,»40 

12.77 

3,600 

16.09 

5,473 

16,07 

5,100 

18,10 

H,B80 

80.11 

8,579 

10.43 

13.90 

3,576 

13.rs5 

3,438 

13.90 

3,875 

12.C0 

2,5H3 

12.30 

2,360 

4,139 
4,636 
6,187 
11,006 
13,156 
10,673 
30,414 
39,480 
22,009 
16,763 
12,800 
14,464 
38,606 
15,763 
10,700 
8,746 
9,844 
8,296 
17,074 
14,834 
16,113 
16,730 
12,434 
10,781 
7,857 
7,791 
12,436 
13,662 


11.90 

3,105 

2.56 

5,380 

11.78 

1,991 

.^016 

13.13 

3,869 

3.00 

8,008 

14,86 

8,980 

8.3S 

13,863 

13,90 

3,987 

2.09 

13.38 

3,860 

3.53 

U,733 

13.76 

2,947 

3.63 

7,735 

11.53 

3,193 

'  2.39 

6,245 

230 


NICARAGUA  CANAL  COMMISSION 


RATING  TABLE  FOR  SAN  CARLOS  RIVER,  AT  CAMP.  THREE  MILES  ABOVE  MOUTH. 

Table  good  for  January,  1898,  only. 


Gage 
height. 

Discharge. 

Gage 
height. 

Discharge. 

Gage 
height. 

Discharge. 

Gage 
height. 

Discharge. 

Feet. 

Second-ft. 

Feet. 

Second-ft. 

Feet. 

8econ<l-ft. 

Feet. 

Second-ft. 

12.5 

9,000 

13.4 

13,960 

14.3 

18,820 

15.2 

23,680 

12.6 

9,540 

13.5 

14,500 

14.4 

19,360 

15.8 

24,220 

12.7 

10,180 

13.6 

15,040 

14.5 

10,900 

15.4 

24,760 

12.8 

10,720 

13.7 

15,580 

14.6 

20,440 

15.5 

25,300 

12.9 

11,260 

13.8 

16,120 

14.7 

20,980 

15.6 

25,840 

13.G 

11,800 

13.9 

16,660 

14.8 

21,520 

15.7 

26,880 

13.1 

12,840 

14.0 

17,200 

14.9 

22,060 

15.8 

26,920 

13.2 

12,880 

14.1 

17,740 

15.0 

22,600 

15.9 

27,560 

13.3 

13,420 

14.2 

18,280 

15.1 

23,140 

16.0 

28,000 

RATING  TABLE  FOR  SAN  CARLOS  RIVER,  AT  CAMP.  THREE  MILES  ABOVE  MOUTH. 
This  table  is  applicable  only  from  February  1,  1898,  to  May  30,  1898. 


Gage 
height. 


Discharge. 


Gage 
height. 


Discharge. 


(lage 
height. 


Discharge. 


Gage 
height 


Discharge. 


Feet. 

Second-ft, 

11.0 

4,100 

11.1 

4,340 

11.2 

4,580 

11.3 

4,820 

11.4 

5,040 

11.5 

5,280 

11.6 

5,520 

11.7 

5,760 

11.8 

0,000 

11.9 

0,250 

12.0 

0,500 

12.1 

6,750 

12.2 

7,000 

12.3 

7,250 

12.4 

7,500 

12.5 

7,750 

12.6 

8,000 

12.7 

8.250 

Feet. 

Second-ft. 

12.M 

8,500 

12.9 

8,750 

13.0 

9,000 

13.1 

9,360 

13.2 

9,720 

18.3 

10,080 

13.4 

10,440 

13.5 

10,800 

13.6 

11,160 

18.7 

11,520 

18.8 

11,880 

13.9 

12,240 

14.0 

12,620 

14.1 

13,000 

14.2 

13,380 

14.3 

13,760 

14.4 

14,140 

14.5 

14,520 

Feet. 
14.6 
14.7 
14.8 
14.9 
15.0 
15.1 
15.2 
15.3 
15.4 
15.5 
15.6 
15.7 
15.8 
15.9 
16.0 
16.1 
16.2 
16.3 


Second-ft. 

14,900 
'  15,280 
15,660 
16,040 
16,420 
16,800 
17,180 
17,560 
17,940 
18,320 
18,700 
19,100 
19,500 
19,900 
20,300 
20,700 
21,100 
21,500 


5'eet. 

8?cond-ft 

16.4 

21,900 

16.5 

22,800 

16.6 

22,700 

16.7 

23,100 

16.8 

23,500 

16.9 

23,900 

17.0 

24,800 

17.1 

24,700 

17.2 

25,100 

17.3 

25,500 

17.4 

25,900 

17.5 

26,300 

17.6 

26,700 

17.7 

27,100 

17.8 

27,500 

17.9 

27,900 

18.0 

28,300 

RATING  TABLE  FOR  SAN  CARLOS  RIVER,  AT  CAMP,  THREE  MILES  ABOVE  MOUTH. 
This  table  is  applicable  only  from  June  1,  1898,  to  November  30,  1898. 


heiX     Discharge. 


SSre       Discharge. 


height. 


Gage 
height. 


Discharge. 


Gage 
height. 


Discharge. 


Feet. 

Second-ft. 

Feet. 

Second-ft. 

Feet. 

Second-ft. 

Feet. 

Second-ft. 

11.0 

4,100 

11.8 

5,910 

12.6 

7,800 

13.4 

9,800 

11.1 

4,320 

11.9 

6,140 

12.7 

8,050 

13.5 

10,050 

11.2 

4,540 

12.0 

6,370 

12.8 

8,800 

13.6 

10,800 

11.3 

4,760 

12.1 

0,600 

12.9 

8,550 

13.7 

10,560 

11.4 

4,980 

12.2 

6,830 

13.0 

8,800 

13.8 

10,830 

11.5 

5,200 

12.3 

7,060 

13.1 

9,050 

13.9 

11,100 

11.6 

5,480 

12.4 

7,300 

13.2 

9,300 

14.0 

11,380 

11.7 

6,680 

12.5 

7,550 

13.3 

9,550 

14.1 

11,660 

APPENDIX   III.— HYDROGRAPHIC   REPORT 


231 


RATING  TABLE  FOR  SAN  CARLOS  RIVER,  AT  CAMP.  THREE  MILES  ABOVE  MOUTH.— Continued. 


heght.     ^K^bargo. 


heS^*t.     Dlscharje. 


heX.     DlBehaw. 


G&ge 
height 

Discbanre 

Feet. 

Second-ft. 

19,6 

34,100 

19.7 

84,700 

19.8 

85,800 

19.9 

85,900 

20.0 

86,500 

20.1 

87,100 

20.2 

87,700 

20.3 

88,800 

20.4 

88,900 

20.5 

89,500 

20.  rf 

40,100 

20.7 

40,700 

20.8 

41,800 

20.9 

41,900 

21.0 

•    •   •   • 

42,500 

•  •    •    • 

•  •   •   • 

Feet. 

8econd-ft 

14.2 

11,940 

14.8 

12,220 

14.4 

12,500 

14.5 

12,780 

14.6 

13,060 

14.7 

13,840 

14.8 

13,620 

14.9 

13,900 

15.0 

14,200 

15.1 

14,500 

15.2 

14,800 

15.8 

15,100 

15.4 

15,400 

15.5 

15,700 

15.6 

16,000 

15.7 

16,380 

15.8 

16,660 

15.9 

17,000 

Feet. 

Second- ft 

16.0 

17,340 

16.1 

17,680 

16.2 

18,020 

16.3 

18,360 

16.4 

18,700 

16.5 

19,050 

16.6 

19,400 

16.7 

19,750 

16.8 

20,100 

16.9 

20,500 

17.0 

21,000 

17.1 

21,500 

17.2 

22,000 

17.3 

22,500 

17.4 

23,000 

17.5 

23,500 

17.6 

24,000 

17.7 

24,500 

?"eet. 

Second- ft 

17.8 

25,000 

17.9 

25,500 

18.0 

26,000 

18.1 

26,500 

18.2 

27,000 

18.3 

27,500 

18.4 

28,000 

18.5 

28,500 

18.6 

29,000 

18.7 

29,500 

18.8 

80,000 

18.9 

30,500 

19.0 

81,000 

19.1 

31,500 

19.2 

82,000 

19.8 

82,500 

19.4 

83,000 

19.5 

33,500 

RATING  TABLE  FOR  SAN  CARLOS  RIVER.  THREE  MILES  ABOVE  ITS  MOUTH. 
This  table  is  applicable  only  from  December  1,  1898,  to  March  31,  1899. 


Gage 


height.    i>i~>»nre. 


S,X      Discharge. 


height. 


Gage 


hofg^^.     Discharge. 


Feet. 

11.0 

11.1 

11.2 

11.3 

11.4 

11.5 

11.6 

11.7 

11.8 

11.9 

12.0 

12.1 

12.2 

12.3 

12.4 

12.5 

12.6 

12.7 

12.8 

12.9 

13.0 


8econd-ft. 
4,280 
4,380 
4,530 
4,680 
4,830 
4,980 
5,140 
5,820 
5,520 
5,740 
5,980 
6,240 
6,500 
6,760 
7,020 
7,280 
7,540 
7,800 
8,060 
8,320 
8,580 


Feet. 

Second-ft. 

18.1 

8,860 

13.2 

9,140 

13.3 

9,420 

18.4 

9,700 

18.5 

9,980 

13.6 

10,260 

13.7 

10,540 

13.8 

10,820 

13.9 

11,100 

14.0 

11,880 

14.1 

11,660 

14.2 

11,940 

14.3 

12,220 

14.4 

12,500 

14.5 

12,780 

14.6 

18,060 

14.7 

13,840 

14.8 

13,620 

14.9 

18,900 

15.0 

14,200 

15.1 

14,500 

Feet. 
15.2 
15.3 
15.4 
15.5 
15.6 
15.7 
15.8 
15.9 
16.0 
16.1 
16.2 
16.8 
16.4 
16.5 
16.6 
16.7 
16.8 
16.9 
17.0 
17.1 
17.2 


Second-ft, 
14,800 
15,100 
15,400 
15,700 
16,000 
16,330 
16,660 
17,000 
17,340 
17,680 
18,020 
18,860 
18,700 
19,050 
19,400 

-  19,750 
20,100 
20,500 
21,000 
21,500 
22,000 


Gage 
height. 

Discharge. 

Feet 

Second-ft 

17.3 

22,500 

17.4 

23,000 

17.5 

23,'>00 

17.6 

24,000 

17.7 

24,500 

17.8 

25,000 

17.9 

25,500 

18.0 

26,000 

18.1 

26,500 

18.2 

27,000 

18.3 

27,500 

18.4 

28,000 

18.5 

28,500 

1H.6 

29,000 

18.7 

29,500 

18.8 

30,000 

18.9 

80,500 

19.0 

31,000 

232 


NICARAGUA  CANAL  COMMISSION 


ESTIMATED  MONTHLY  DISCHARGE  OF  SAN  CARLOS  RIVER  THREE  MILES  ABOVE  ITS  MOUTH. 

Drainage  area»  1,450  square  miles,  approximately. 


Month. 


Di^charflre  in  Second-feet. 


Maximum. 


Minimum. 


Mean. 


Total  in 
Acre-feet. 


1898. 

January  (10-31) 28,000  10,560  16,055  700,582 

February 34,300  7,400  13,530  751,380 

March 11,341  5,140  7,030  432,260 

April   10,080  4,220  6,038  859,285 

May   11,880  4,100  5,560  841,870 

June 32,250  5,200  10,720  637,880 

July 41,600  8,400  14,094  866,605 

August 15,730  8,800  10,990  675,750 

September 14,200  7,420  10,319  614,023 

October 82,500  8,180  12,880  791,960 

November 32,260  9,680  15,440  918,750 

December 19,920  5,850  9,290  671,220 

Total,  1898 7,661,565 

1899. 

January 14,200  5,720  7,865  483,600 

February 13,340  4,940  7,360  408,750 

March 8,060  4,300  5,400  332,030 


Run-ofT, 

t 

Depth 
in  inches, 

Second-feet 
per  sq.  mile. 

9.09 

11.1 

9.68 

9.3 

5.53 

4.8 

4.69 

4.2 

4.38 

8.8 

8.26 

7.4 

11.18 

9.7 

8.76 

7.6 

7.92 

7.1 

10.26 

8.9 

11.88 

10.6 

7.88 

6.4 

6.28 
5.31 
4.27 


5.4 
5.1 
3.7 


OciiOA  Station  on  the  San  Juan. 

One  of  the  most  important  as  well  as  most 
disputed  points  regarding  hydrographic  knowl- 
edge in  Nicaragua  is  the  discharge  of  the  Rio  San 
Jnan  at  Ochoa,  where  it  is  proposed  to  build  a 
high  dam.  A  station. was  established  here  on 
December  30,  1897.  A  vertical  pine  gage  was 
fastened  to  an  overhanging  tree  on  the  right 
bank,  and  was  graduated  to  feet  and  tenths,  to 
15  feet,  and  continued  upward  on  another  plank 
fastened  to  the  same  tree. 


A  standard  copper  bench  mark  of  the  TT.  S. 
Geological  Survey  was  established  on  the  right 
bank  near  the  tree  which  bears  the  gage.  It  is 
a  copper  plate  placed  horizontally  on  top  of  a 
stump,  with  its  stem  driven  into  an  auger  hole 
in  the  stump.  It  is  28.10  feet  above  the  zero 
of  the  gage.  The  channel  at  this  point  is 
straight,  and  the  bottom  is  reasonably  perma- 
nent. 


APPENDIX   III.— HYDROGRAPHIC   REPORT 


23S 


234 


NICARAGUA  CANAL  COMMISSION 


DAILY  GAGE  HEIGHT  OF  SAN  JUAN  RIVER  AT  OCHOA  FOR  1898-9. 


iao8. 

Jan. 

Feb. 

Mar. 

Apr. 

May. 

June. 

July. 

Au^. 

Sep. 

Oct, 

Nov. 

Dec. 

lovtf. 

Jan. 

Feb. 

Mar. 

Day. 

X  •  •  •  • 

14.80 

7.83 

7.50 

5.38 

4.76 

6.65 

11.30 

8.63 

7.93 

8.66 

9.65 

10.90 

8.60 

7.60 

7.22 

2.... 

14.45 

9.45 

7.20 

5.30 

4.55 

6.15 

12.38 

8.90 

7.98 

9.75 

9.18 

11.20 

9.32 

7.58 

7.12 

o .   .   •   • 

15.83 

10.48 

7.00 

5.28 

4.56 

5.60 

12.75 

9.38 

7.88 

8.63 

9.00 

10.60 

9.85 

7.47 

7.02 

4.... 

15.60 

9.30 

6.85 

6.40 

4.53 

6.43 

12.40 

9.13 

7.93 

8.45 

9.05 

10.20 

9.30 

7.38 

6.92 

o.  . . . 

13.38 

12.70 

7.60 

8.10 

4.68 

6.30 

12.35 

9.53 

8.00 

8.65 

8.96 

9.86 

9.55 

7.30 

6.88 

6. . . . 

13.55 

12.45 

7.73 

8.58 

4.  .58 

6.20 

11.08 

9.76 

8.20 

8.93 

8.90 

9.75 

9.28 

7.30 

6.78 

7 

14.70 

10.63 

7.18 

7.65 

4.55 

6.48 

10.43 

9.40 

8.13 

8.75 

9.10 

9.76 

8.92 

7.50 

6.78 

8.... 

13.30 

9.78 

6.90 

7.35 

4.50 

6.03 

11.13 

9.25 

7.90 

8.73 

9.78 

9.60 

9.07 

7.45 

7.28 

9.  . . . 

11.23 

9.40 

6.83 

7.10 

.4.40 

6.05 

12.95 

8.75 

7.80 

9.00 

10.98 

9.48 

8.92 

7.30 

7.40 

10.... 

10.95 

9.13 

6.75 

6.35 

4.33 

6.28 

13.85 

8.78 

7.78 

8.86 

10.88 

10.43 

9.07 

7. 25 

6.98 

11.... 

10.40 

8.78 

6.73 

6.10 

6.40 

6.08 

12.48 

8.63 

10.68 

8.68 

10.43 

12.60 

8.97 

7.25 

6.75 

12.... 

9.98 

8.55 

6.58 

6.08 

6.18 

5.73 

11.08 

8.65 

9.65 

8.85 

10.23 

11.10 

9.85 

7.45 

6.65 

13 

9.63 

8.43 

6.43 

6.95 

4.95 

5.90 

10.53 

9.30 

10.53 

8.7rf 

13.08 

10.38 

10.37 

8.38 

6.60 

14.... 

9.33 

8.10 

6.33 

5,70 

4.65 

6.13 

10.10 

11.65 

10.45 

8.88 

13.68 

9.90 

9.90 

8.98 

6.55 

15 

8.95 

7.83 

6.18 

5.50 

4.63 

6.23 

9.68 

10.45 

9.65 

8.58 

12.30 

9.53 

9.97 

8.15 

6.52 

16 

8.90 

7.68 

6.08 

5.35 

4.70 

6.28 

9.28 

9.65 

11.65 

8.80 

13.28 

9.38 

10.65 

7.98 

6.48 

17.... 

9.15 

7.50 

6.08 

5.25 

4.93 

7.08 

9.15 

8.98 

10.73 

8.88 

17.20 

11.05 

9.95 

7.90 

6.35 

18... 

•   ■   •    • 

7.38 

6.18 

.5.28 

5.25 

6.38 

9.05 

8.53 

9.88 

11.30 

15.03 

10.15 

9.42 

8.26 

6.30 

19.... 

•    •   ■   • 

7.40 

5.95 

6.;'.5 

6.40 

9.45 

10.15 

8.25 

9.53 

1 1.95 

13.15 

9.85 

9.17 

8.20 

6.28 

20. . . . 

•   •   •  • 

7.28 

5.83 

5.15 

7.33 

10.53 

10.88 

8.20 

9.70 

11.83 

12.18 

9.08 

9.02 

8.00 

6.25 

21 

•   •  •   • 

7.18 

5.70 

5.10 

6.53 

11.45 

10.85 

8.28 

9.60 

10.85 

11.48 

8.78 

8.75 

8.22 

6.22 

22.... 

•   •   •   • 

7.10 

5.75 

6.05 

7.08 

10.28 

10.38 

8.85 

9.95 

10.25 

10.90 

8.60 

8.52 

7.80 

6.12 

23.... 

8.80 

7.05 

5.70 

5.10 

6.15 

9.75 

9.65 

8.60 

11.06 

10.38 

10.48 

8.63 

8.45 

8.10 

6.02 

24   ... 

8.35 

6.90 

5.65 

5.13 

5.85 

11.55 

9.10 

8.60 

9.76 

11.03 

10.10 

8  33 

8.35 

7.90 

6.00 

25. . . . 

8.13 

6.90 

5.93 

6.00 

5.78 

11.98 

9.05 

8.40 

9.45 

10.75 

10.00 

8.26 

8.35 

7.70 

5.98 

26.... 

8.10 

6.93 

6.15 

4.98 

5.63 

10.90 

8.85 

8.40 

9.65 

12.70 

10.23 

8.18 

8.15 

7.42 

5.90 

27 

8.30 

7.28 

6.38 

5.00 

5.50 

12.00 

8.63 

8.40 

9.93 

11.40 

10.70 

8.15 

8.02 

7.50 

5.82 

28.... 

8.53 

7.43 

6.20 

4.85 

5.93 

12.76 

9.18 

8.40 

10.43 

10.58 

11.85 

8.13 

7.97 

7.40 

5.80 

29 

8.30 

•   •   •   • 

5.88 

4.78 

5.75 

12.95 

9.45 

8.18 

9.30 

10.15 

11.68 

8.30 

7.82 

•   •   •   • 

5.80 

80.... 

8.10 

•   •   •   • 

5.65 

4.70 

5.50 

11.18 

9.70 

8.10 

8.90 

9.75 

10.95 

8.25 

7.72 

•   •   •   • 

5.78 

31.... 

8.03 

•    •   •   • 

6.53 

•   •   •   • 

6.28 

•   •   •   • 

9.68 

7.98 

•   •   •   • 

9.83 

•    •   •    • 

8.30 

7.65 

•   •   •   • 

6.70 

For  purposes  of  current  meter  measuremeiits 
it  was  not  permissible  to  extend  a  cable  over  the 
river  at  this  point  on  account  of  navigation.  It 
was  first  intended  to  make  measurements  by 
means  of  a  boat  anchored  to  a  small  cable 
stretched  across  the  river,  which  should  carry 
tags  indicating  distances  from  the  initial  point, 
and  which  when  not  in  use  was  to  be  held  against 
the  bottom  of  the  river  by  means  of  sinkers. 
Experience  on  this  line,  however,  soon  demon- 
strated that  it  would  be  difficult,  if  not  imprac- 
ticable, to  maintain  a  small  cable  in  the  position 
proposed  on  account  of  the  large  quantities  of 
driftwood,  leaves  and  brush  passing  down  the 


river,  especially  in  times  of  flood,  when  the 
gaging  apparatus  would  be  most  in  demand. 
Another  project  was  therefore  inaugurated, 
which  was  the  anchorage  of  a  number  of  buoys 
at  known  distances  from  the  initial  point,  said 
buoys  to  be  constructed  of  "balsa,"  a  very  light, 
bulky  endogenous  wood  much  used  in  the  con- 
struction of  rafts,  etc.  This  method  of  marking 
distances  from  the  initial  point  was  successfully 
employed  for  several  months  during  the  season 
of  low  water,  but  as  the  rains  increased  and 
freshets  began  to  come  down  the  river  the  great 
quantity  of  leaves  and  brush  carried  by  the 
water  attached  themselves  to  the  buovs  and  their 


APPENDIX   III.— HYDROGRAPHIC   REPORT 


235 


anchorages  until  they  were  either  carried  be- 
neath the  surface  of  the  river  or  washed  awav 
entirely.  The  method  permanently  adopted  re- 
quired the  employment  of  an  additional  instni- 


ment  man  to  manipulate  a  telescope  on  shore  and 
measure  the  distance  of  the  boat  during  the  pro- 
cess of  gaging,  by  means  of  a  stadia  rod. 


LIST  OF  DISCHARGE  MEASUREMENTS  MADE  ON  SAN  JUAN  RIVER  AT  OCHOA. 


Date. 


Hydrogrraphcr. 


Meter        Gage  height    Area  of  Rection    Mean  velocity    Discharge      •unmar-va 
number.  (feet).  (square  feet),      (ft.persec'd).    Jsecond-ft.)    "^«™a'^»^»- 


Jan.     8 
*'      12 

Feb.     8 

'*      16 

*♦      38 

Mar.  10 

«»      19 

Apr.     1 
i*      14 

«»      27 

Mav  10 

Juu.    4 

»'      17 

♦'      23 

''      20 

*'      28 

Jiilv    8 

♦'  '    11 

♦♦       1(5 

♦'       19, 

'*      25, 

♦'      28 

AU!^.     1 

8, 

li        ~ 

Sep. 

ii 
II 

Oct. 


< . 

3. 
12, 
1«. 
2«, 

1 
17. 
18. 

8. 
13. 
17. 
19. 
30. 


it 

Nov, 

i( 

ii 
It 

it 

Dec.  12 

"      19. 

»♦      22. 

»♦      28. 

'»      30. 
1899. 
Jan.     0. 

"      13. 

*♦      21. 

♦»      26 

"      30. 
Feb.    7. 

♦»      21. 

'»      25. 

»'      28. 
Mar.    3. 

»«         7. 

»'      13. 

»»      31 . 


G.  R.  Wadlelgh. 


it 
it 
ti 
ti 
ti 
ti 
it 
it 
it 
it 
ti 
it 
it 


A.  P.  Davis 

G.  R.  Wadleigh, 


it 

it 
it 
(t 
ti 

it 

it 
it 


H.  S.   Reed 


it 
it 
it 
It 
it 
ti 
it 
it 
it 
It 
ti 
ti 
it 
(t 
tt 
ti 

ti 
it 
it 
•t 
it 
it 
ti 
it 
it 
tt 
it 
it 
it 


1985 

11.94 

13,100 

4.00 

52,400 

1985 

9.87 

11,940 

3.67 

43,880 

1985 

8.80 

9,906 

3.33 

83,050 

1985 

9.78 

10,916 

8.75 

40,913 

1985 

7.65 

8,966 

3.29 

29,458 

1985 

7.40 

8,602 

3.21 

27,600 

1985 

6.73 

8,132 

3.07 

24,974 

1985 

5.95 

7,703 

2.89 

22,270 

1985 

5.35 

7,225 

2.91 

21,017 

1985 

5.73 

7,359 

3.03 

22,327 

1985 

4.99 

6,728 

2.72 

18,290 

1985 

4.30 

5,654 

2.S6 

16,145 

1985 

5.41 

6,637 

3.08 

20,461 

1985 

6.64 

7,794 

3.84 

26,066 

1985 

9.68 

10,922 

3.88 

42,850 

1894 

11.13 

11,994 

3.88 

46,529         Falling, 

1985 

12.91 

14,462 

4.25 

61,410              »' 

1985 

11.52 

13,418 

3.86 

51,821         Rising. 

1985 

12.42 

14,438 

3.80 

55,089 

1985 

9.12 

11,211 

3.32 

87,213 

1985 

10.53 

12,586 

3.66 

46,098 

1985 

8.96 

9,782 

3.78 

36,940 

1985 

9.56 

10,506 

3.97 

39,832 

1985 

8.68 

9,826 

3.56 

35,980 

1985 

10.21 

11,094 

3.84 

42,640 

1985 

9.42 

10,359 

3.63 

37,647 

65 

7.85 

8,938 

3.68 

32,984 

65 

9.38 

10,336 

4.00 

41,199 

65 

12.02 

12,761 

4.47 

57,047 

65 

9.43 

9,895 

4.24 

41,975 

65 

8.52 

8,815 

3.97 

34,971 

65 

8.88 

9,026 

4.44 

40,087 

65 

11.79 

12,076 

4.85 

58,620 

65 

9.77 

10,800 

4.40 

47,472 

65 

14.05 

14,171 

5.59 

79,210 

65 

17.43 

19,717 

5.82 

104,930 

65 

13.00 

14,734 

4.53 

66,800 

65 

10.89 

12,057 

4.39 

52,950 

65 

11.02 

12,069 

4.23 

51,042 

65 

9.28 

10,872 

3.89 

41,904 

65 

8.60 

10,286 

3  88 

39,859 

65 

8.10 

9,.565 

8.71 

35,452 

65 

8.25 

9,767 

3.80 

37,089 

65 

9.20 

10,626 

3.90 

41,404 

65 

10.21 

12,006 

4.04 

48,580 

65 

8.75 

10,25? 

8.74 

38,846 

65 

8.12 

9,779 

3.55 

34,688 

65 

7.71 

9,176 

3.59 

32,976 

65 

7.52 

9,113 

3.52 

32,115 

65 

8.13 

9,775     • 

3.67 

85,852 

65 

7.68 

9,393 

3.56 

88,416 

65 

7.87 

8,972 

8.49 

81,314 

65 

7.01 

8,863 

3.41 

30,184 

65 

6.80 

8,954 

3.30 

29,558 

65 

6.60 

8,372 

3.35 

28,048 

65 

5.70 

7,589 

3.08 

23,369 

NICARAGUA   CANAL  COMMISSION 


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it                                    ^ 

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^^ 

APPENDIX  III.— HYDROGRAPHIC  REPORT 


237 


The  highest  measurement  of  discharge  yet 
made  at  this  point  was  on  November  17,  at  a 
gage  height  of  17.43  feet,  when  tJbe  river  was 
discharging  104,928  cubic  feet  per  second.  At 
this  stage  the  river  was  about  8.5  feet  below  the 
flood-plain  at  Ochoa,  the  formation  of  which 
indicates  that  it  is  sometimes  overflowed. 

Dr.  C.  W.  Hayes,  geologist  of  the  expedition, 
expresses  the  opinion  that  this  flood-plain  is  at 
intervals  of  ten  to  thirty  years  covered  by  the 
floods  of  San  Juan  river  to  a  depth  of  more 
than  six  inches,-  but  less  than  three  feet.  In 
other  words,  maximum  gage  readings  of  26.5  to 
29  may  be  expected  with  moderate  frequency  at 
Ochoa  station.  The  considerations  on  which 
this  conclusion  is  based  are  outlined  below : 

Physical  Chabacteristics  of  the  San  Juan 
Flood-plain.— The  San  Juan  river  from  the  mouth 
of  the  San  Carlos  eastward  flows  in  a  vaUey  which 
has  recently  been  depressed  below  sea  level.  This 
old  valley  since  submergence  has  been  filled  with 
sediment  contributed  chiefly  by  the  San  Carlos  and 
Saraplqui,  but  in  some  measure  also  by  the  smaller 
tributaries.  The  San  Juan  may  at  one  time  have 
flowed  into  an  estuary  which  has  filled  from  its  head 
seaward,  and  after  the  estuary  had  been  filled  a 
delta  was  pushed  beyond  into  the  open  sea.  The 
alluvial  plain  thus  formed  had  from  the  start  a  slope 
dependent  upon  the  volume  of  the  river  and  the 
quantity  and  character  of  the  sediment  which  it  car- 
ried. As  the  mouth  of  the  river  was  pushed  eastward 
its  bed  and  its  entire  flood-plain  were  raised  by  the 
deposit  of  alluvium,  the  seaward  slope  always  re- 
maining the  same,  except  as  the  volume  of  the  river 
and  its  load  may  have  varied.  This  process  is  still 
going  on.  As  the  length  of  the  river  increases  by 
increments  to  its  delta,  its  flood-plain  is  built  up  so 
as  to  preserve  the  long  gradient. 

Throughout  this  process  of  alluviation  the  eleva- 
tion of  the  flood-plain  above  the  river  bed  has  re- 
mained practically  the  same,  since  this  is  dependent 
on  the  relative  volumes  of  the  river  at  extreme  stages 
of  high  and  low  water  and  on  the  relative  amount 
of  fine  and  coarse  sediment  which  it  carried.  It  is 
important  to  note  the  entire  absence  of  terraces  on 
the  San  Juan.  As  river  terraces  are  fossil  flood- 
plains,  marking  a  former  higher  flowage  plain,  their 
absence  in  a  river  basin  may  be  regarded  as  good 


evidence  that  the  river  is  not  cutting  down  but 
building  up  its  bed,  and,  at  a  corresponding  rate,  its 
flood-plain  also.  * 

The  sediment  carried  by  the  river  may  be  classed 
as  silt  and  sand.    The  former  consists  of  clay,  vege- 
table matter  and  flne  sand;  the  latter  chiefly  of  rather 
coarse  sand  and  flne  gravel,  with  some  pebbles  up  to 
an    inch    in    diameter.    The    sand    is    transported 
chiefly  by  rolling  along  the  bottom  of  the  river  bed 
and  at  all  stages  of  water,  although  much  more  is 
carried  at  flood  than  at  low  water  by  reason  of  the 
higher  velocity.    By  far  the  greater  part  of  the  sand 
is  carried  within  a  few  inches  of  the  river  bed  and 
very  little  ever  reaches  more  than  a  few  feet  from 
the  bottom.    The  silt,  on  the  other  hand,  is  carried 
by  suspension  in  the  body  of  the  stream  and  varies 
in  amount  with  its  volume  only  because  it  is  fur- 
nished more  abundantly  with  flood  waters  and  not 
because  it  cannot  be  carried  J}y  the  slacker  current 
at  low  water.    The  silt  remains  in  suspension  until 
quiet  water  is  reached,  and  hence  is  either  carried  far 
out  to  sea  or  is  deposited  on  the  flood-plain  when  that 
is  overflowed.    Although  the  flood-plain  has  the  same 
seaward  slope  as  the  river  bed,  or  a  slope  slightly 
greater,  it  receives  deposits  of  the  flnest  silt  when 
flooded.    The  requisite  retardation  of  the  current  is 
effected  chiefly  by  the  dense  growth  of  vegetation 
which   everywhere   covers   it.    This    vegetation   not 
only  checks  the  current,  but  acts  as  a  kind  of  fllter 
by  which  the  sediment  is  caught  and  held.    Hence 
the  deposit  is  more  rapid  on  the  immediate  river 
bank  and  a  natural  levee  is  built  up,  back  of  which 
is  a  lower,  swampy  area.    A  subordinate  reason  for 
the  more  rapid  deposition  of  silt  on  the  river  bank 
is  that  the  water. covering  the  swamps  back  from  the 
river  is  largely  derived  from  the  rainfall  in  the  im- 
mediate vicinity,  hence  free  from  silt,  and  only  in 
part  from  the  overflow  of  silt-laden  waters  from  the 
river.    This  levee  is  generally  from  one  to  three  feet 
higher  than  the  depressed  area,  though  the  difference 
in  elevation  is  naturally  much  greater  in  the  case  of 
a  wide  than  a  narrow  flood-plain.    It  is  manifest  that 
the  flood-plains  are  undergoing  continuous  degrada- 
tion.   This  is  favored  by  the  unconsolidated  character 
of  the  material  and  is  retarded  by  the  dense  covering 
of  vegetation  and  the  low  slopes.    If  the  bed  of  the 
stream  should  remain  for  a  considerable  time  at  a 
qonstant  elevation  a  condition  of  equilibrium  would 
at  length  be  reached  between  the  forces  tending  to 
build   up  and  those  tending  to  degrade  the  flood- 
plains.    As  this  condition  was  approached  the  floods 
of  sufficient  height  to  overflow  the  banks  would  be- 
come less  frequent  with  the  increased  height  of  the 
banks,  and  the   deposition  •  of  silt  would   be  corre- 
spondingly  slower.    Further,   It  Is  only   during  the 


238 


NICARAGUA  CANAL  COMMISSION 


comparatively  rapid  building  of  the  flood-plain  that 
conditions  favor  the  formation  of  the  natural  levee. 
On  the  immediate  bank  of  the  river  degradation  is 
most  rapid,  chiefly  by  reason  of  the  proximity  to 
steep  slopes  and  through  the  process  of  the  flattening 
of  slopes.  The  amount  of  sediment  deposited  by 
standing  water  varies  directly  as  the  depth  of  the 
water,  hence  a  flood  which  barely  overtops  the  levee 
may  fill  the  depressed  area  behind  with  a  considerable 
depth  of  water,  and  if  the  majority  of  the  floods 
which  are  building  the  plain  thus  barely  overtop  the 
levee  they  will  tend  to  bring  the  entire  surface  of  the 
flood-plain  to  a  level.  The  fact  that  the  flood-plains 
are  still  growing,  as  proved  by  the  absence  of  ter- 
races and  the  existence  of  natural  levees,  may  there- 
fore be  regarded  as  good  evidence  that  the  floods 
rise  to  a  considerable  height  above  its  surface. 

A  secondary  flood-plain  is  frequently  observed.  It 
is  usually  quite  narrow  and  may  occupy  any  position 
between  the  main  flood-plain  and  the  bars,  which  are 
uncovered  only  at  the  lowest  stages.  It  is  on  such 
flood-plains  that  the  most  rapid  deposition  is  taking 
place.  They  always  occupy  the  concave  side  of  the 
river,  opposite  which  active  cutting  is  going  on. 
They  serve  to  compensate  for  the  lateral  corrasion 
and  preserve  the  normal  river  section.  As  their  sur- 
face approaches  that  of  the  main  flood-plain  deposi- 
tion becomes  gradually  slower  until  they  merge  with 
the  broader  plain. 

From  considerations  given  more  fully  elsewhere,  it 
appears  probable  that  the  bed  of  the  San  Juan  from 
the  foot  of  the  Machuca  rapids  to  Lake  Nicaragua, 
differs  from  that  below  Ochoa  in  that  it  is  being 
lowered  instead  of  raised.  The  lowering  between  the 
foot  of  the  Machuca  rapids  and  the  head  of  the  Toro 
rapids  has  probably  been  considerable,  and  a  careful 
examination  of  this  portion  of  the  river  valley  should 
reveal  remnants  of  former  flood-plains  in  the  shape 
of  terraces.  Above  Sabalos  the  river  has  probably 
remained  at  a  constant  elevation  for  a  long  time  and 
the  flood-plains  have  perhaps  reached  nearly  the  point 
of  equilibrium.  Deposition  of  alluvium,  however,  is 
much  slower  here  than  farther  down,  since  the  water 
leaving  the  lake  is  practically  clear  and  only  a  small 
amount  of  sediment  is  added  to  it  by  the  few  tribu- 
taries between  the  lake  and  Sabalos.  Hence  the  sur- 
face of  the  flood-plains  probably  marks  very  nearly 
the  stream  height  of  water  at  the  normal  high  floods. 

The  Relation  op  Floods  to  the  Flood-plain. — 
The  floods  of  all  rivers  may  be  conveniently  classed 
in  three  categories:  (1)  normal  annual  floods;  (2) 
normal  high  floods;  (3)  exceptional  high  floods.  The 
normal  annual  floods  of  the  San  Juan  do  not  reach 
the  main  flood-plain,  at  least  in  the  vicinity  of  Ochoa. 
They  probably  fail  to  overtop  the  banks  by  at  least 


three  to  flve  feet,  covering  only  the  secondary  flood- 
plains  mentioned  above.  On  these  they  leave  con- 
siderable deposits,  the  character  of  the  material  de- 
pending on  their  elevation.  It  varies  from  coarse 
sand  on  the  bars  just  emerging  above  low  water  to 
flne  silt  where  the  secondary  plain  approaches  the 
main  flood-plain. 

The  normal  high  floods  undoubtedly  cover  the  flood- 
plains.  While  it  is  impossible  to  make  exact  state- 
ments either  as  to  the  frequency  of  the  floods  or  the 
depth  of  the  water  on  the  flood-plain,  there  is  some 
basis  for  a  tolerably  fair  estimate.  From  the  con- 
siderations given  above  it  is  certain  that  these  high 
floods  are  of  sufficient  frequency  and  of  sufficient 
height  so  that  the  depth  of  the  alluvium  which  they 
deposit  exceeds  the  surface  degradation  in  the  in- 
terval from  one  flood  to  another.  The  two  factors 
favoring  rapid  deposition  are  abundance  of  sediment 
and  the  dense  vegetation  of  the  flood-plains.  The 
latter  also  retards  the  degradation  by  projecting  the 
unconsolidated  material.  With  these  favorable  con- 
ditions for  deposition  we  should  expect  to  find  the 
flood-plains  built  up  nearly  to  the  limit  flxed  by  the 
extreme  normal  floods.  That  it  has  not  reached  the 
limit  appears  from  the  presence  of  the  natural  levees, 
for  these,  as  shown  above,  would  disappear  when  the 
point  of  equilibrium  was  reached.  Moreover,  fre- 
quent floods  which  barely  overtopped  the  banks 
would  tend  to  obliterate  the  inequalities.  Hence  the 
presence  of  these  levees  and  other  inequalities  in  the 
flood-plain  would  indicate  that  the  floods  were  at 
rather  long  intervals,  but  that  they  covered  the  plain 
to  a  considerable  depth.  From  these  considerations 
it  would  seem  probable  that  at  intervals  of  ten  to 
thirty  years  floods  may  be  expected  in  the  San  Juan 
of  sufficient  height  to  cover  the  flood-plains  in  the 
vicinity  of  Ochoa  to  a  depth  of  more  than  six  inches, 
but  less  than  three  feet. 

All  large  rivers  are  liable  to  exceptional  high  floods, 
due  to  a  rare  combination  of  circumstances,  which 
take  place  at  long  intervals,  probably  measured  by 
generations  or  centuries.  Such  floods  are  too  vari- 
able in  height  and  come  at  too  great  intervals  to 
produce  a  flood-plain  or  other  permanent  record. 
They  are  liable  to  effect  extensive  changes  in  the 
course  of  the  river  and  in  its  banks  and  in  the  vegeta- 
tion growing  on  the  flood-plains,  but  these  effects  are 
all  of  a  temporary  nature  and  are  quickly  obliterated. 
The  exceptional  nature  of  these  floods,  however,  and 
the  long  intervals  at  which  they  are  to  be  expected, 
remove  them  from  among  the  agents  which  must  be 
provided  against  in  the  construction  of  controlling 
works. 

C.  W.  Hayes. 


APPENDIX   III.— HYDROGRAPHIC   REPORT 


239 


Plotting  all  observations  of  discharge,  so  far 
taken  as  abscissas,  with  corresponding  gage 
heights  as  ordinates,  we  obtain  a  curve  indicating 
the  relation  of  gage  height  to  discharge,  showing 
that  the  ratio  of  increase  of  discharge  to  increase 
of  gage  height  is  not  constant.  The  curve  is 
concave  downward,  tending  toward  a  horizontal 
position,  showing  that  the  increase  of  discharge 
for  increase  of  gage  height  is  greater  at  high 
stages  than  at  low  stages,  but  above  a  medium 
stage  of  the  river  the  line  curves  but  slightly, 
and  though  the  concavity  is  still  downward,  the 
curve  approaches  a  straight  line,  or  in  other 
words,  the  ratio  between  gage  height  and  dis- 
charge approaches  constancy.  If  we  assume  as 
constant  the  direction  given  to  the  line  by  the 
higher  measurements,  and  continue  it  upward  as 
a  straight  line,  we  obtain  as  the  discharge  corre- 
sponding to  A  gage  height  of  28  feet,  about 
200,000  cubic  feet  per  second.     (See  Plate  IX.) 

If  any  curvature  be  given  the  extrapolated 
portion  of  the  curve  it  will  increase  this  amount. 

If  the  same  course  of  reasoning  be  applied  to 
the  flood-plain  on  the  Eio  San  Carlos  we  find 
that  its  maximum  discharge  must  be  about  100,- 
000  cubic  feet  per  second. 

Similarly  it  may  be  proved  by  extrapolating 
the  curve  discharge  of  the  Eio  San  Juan  at  Fort 
San  Carlos,  that  at  the  stage  of  111  feet  above 
sea  level  the  lake  must  have  discharged  nearly 
50,000  cubic  feet  per  second. 

When  the  measurement  of  November  17  that 


gave  a  discharge  at  Ochoa  of  104,928  second- 
feet  was  made,  the  Eio  San  Carlos  was  discharge 
ing  only  32,265,  leaving  72,663  as  the  amount 
coming  down  the  San  Juan  proper,  of  which 
probably  not  more  than  28,663  were  flowing 
from  the  lake,  leaving  44,000  to  be  supplied  by 
the  small  tributaries  between  the  lake  and  Boca 
San  Carlos.  With  such  an  indicated  discharge, 
it  would  not  be  excessive  to  assume  a  maximum 
for  these  tributaries  of  50,000  cubic  feet  per 
second,  and  we  have  the  maximum  flood  at 
Ochoa  made  up  as  follows: 

Second-feet. 

Maximum  Eio  San  Carlos 100,000 

Maximum  discharge  from  lake  . . .   50,000 
Maximum  small  tributaries 50,000 

Maximum  at  Ochoa 200,000 

The  highest  observed  discharge  of  the  Sara- 
piqui  is  30,000  cubic  feet  per  second.  It  is 
probable  that  the  extreme  maximum  is  not  much 
less  than  60,000  cubic  feet  per  second.  The 
Machado,  San  Francisco,  Tamborcito  and  San 
Juanillo,  and  a  large  number  of  lesser  creeks, 
contribute  a  large  aggregate  in  time  of  flood, 
so  that  it  is  probable  that  at  rare  intervals  the 
increment  to  the  waters  of  the  San  Juan  below 
Ochoa  may  amount  to  100,000  cubic  feet  per 
second.  Such  an  occurrence  coincident  with 
extreme  flood  conditions  above  Ochoa  would 
make  a  total  of  300,000  cubic  feet  per  second 
discharging  into  the  Caribbean  through  the 
various  mouths  of  the  San  Juan. 


RATING  TABLE  FOR  SAN  JUAN  RIVER  AT  OCHOA. 
This  table  is  applicable  only  from  January  1,  1898,  to  July  9,  1898. 


Gaffe 
hel^t. 

Dischangre. 

Oa^e 
height. 

Dischargre. 

Gage 
height. 

Discharge. 

Gage 

hei^t 

Discharge. 

Feet. 
4.0 
4.1 
4.2 
4.8 
4.4 

Seoond-ft. 
15,500 
15,750 
16,000 
16,250 
10,500 

Feet. 
4.5 
4.6 
4.7 
4.8 
4.9 

Second-ft. 
16,750 
17,010 
17,290 
17,590 
17,900 

Feet 

5.0 

5.1 

5.2 

5.8 

5.4 

Second-ft. 
18,220 
18,650 
18,890 
19,240 
19,590 

Feet. 
5.5 
5.6 
5.7 

5.8 
5.9 

Second-ft. 
19,950 
20,820 
20,690 
21,070 
21,460 

NICABAQUA  CANAL  COMMISSION 


Page  halght.   Dtocharge. 
Fe«t.  S«cond-rt. 

6.0  31,H60 

33,370 
S3,RS0 
33,120 

M,5T0 
34,030 
34,SO0 
25,000 
3S,530 
36,080 
2H,6S0 


RATINQ  TABLE  FOR  SAN  JUAN  RIVER  AT  OCHOA.— ConUnued. 


37,11 


,730 


29,380 
39,930 
30,480 
31,030 
31,SM0 
33,130 
33,680 
88,380 
83,790 


Gage  height-    Dlaoharge. 


3T,0IM) 
37,080 

38,1  HO 


Page  height.   Dlaohargc, 


Gage  height.     Dl»ch»igB. 


8ec«»<l-tt. 

3.6 

03,880 

49,180 

3.6 

63,030 

40,730 

3.7 

63,480 

60,380 

S.H 

64,030 

8.9 

64.580 

61,880 

4.0 

65,180 

B1,B80 

66,680 

4.3 

66,330 

63,080 

4.S 

66,780 

63,580 

4.4 

67,830 

4.6 

67,880 

64,680 

4.6 

68,430 

55,230 

4.7 

68,980 

4.8 

69,530 

56,830 

4.9 

70,080 

66,880 

5.0 

70,630 

57,480 

6.1 

71,180 

5.3 

71,730 

58,630 

6.3 

73,380 

5H,080 

6.4 

K,830 

5.5 

78,780 

60,180 

6.6 

73,080 

60,730 

5.7 

74,480 

RATING  TABLE  FOR  SAN  JUAN  RIVER  AT  OCHOA. 
ThU  table  la  applicable  only  Jrom  July  9,  1898.  to  December  51,  1898. 

_  Gage  height.    Dlachargn. Gage  height.    Discharge . Bage  height.    IHat'hatge. 


16,000 
16,2.50 
16.600 
16,760 
17,010 
17,390 
17,590 
17,900 


30,330 
30,690 
31,070 


30,480 
31,030 
31,580 
32,180 
82,680 
33,330 
33,780 


36,980 
86,630 
37,080 
37,830 


SecoDd-ft. 

.no.eoo 

51,300 

52,100 
.53,900 
63,700 

65i300 
66,160 
57,000 
57,850 
58,700 
59,550 
60,400 
61,250 
63,100 
82,1150 
68,800 
64,650 
65,500 
06,350 
67,300 
68,050 


83,100 
83,000 
83,000 
84,800 
86,700 
86,600 
87,500 
88,400 
89,300 
90,300 
91,100 
92,000 
93,900 
93,800 
94,700 
95,600 


47,100 
47,750 

48,400 


105,500 
106,400 
107,300 


NICARAGUA  CANAL  COMMISSION 


^...„„.   .....  -..=.    ..,. 

.UCU,T 

_     r  "    

™.l. 

If      ^ 

'           t 

J  -              .  ..( 

"^:T"1"""""^'""::;: 

....j  Lk,„i 

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m  I 

1 

'V 

■        TK^'^'T 

I           i    1   i 

■■^"T-ir:-7;;vt: 

.     Air     iliil.^j      1.. 

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^    v-^^A^-'       .1 

-'■■i-'-J,  A '    1    '     '     ' '     '     '    i. '             «- 

-  1 1  Ul — Mill   INN  -LLLll 

DIAGRAM  OF  THE  DAILY  MEAN  DISCHARGE  IN  CUBIC  FEET 


PER  SECOND  OF  THE  RIO  SAN  JUANlMI 


1 

APPENDiX  3,  PLATE  X 

...    _      _ 

r 

1 

ui         iliJi    \i 

i 

ll 

fk   \f^ 

^H  /i 

\ 

""%:r^r' 

i. 

\     J 

^.^.__       L    u- 

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._L ._Jl 

/^U^     _ 

^J^ 

t-^..j^r-il 

,__^____. 

l\    hi 

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\'i               *V  ^"        "3   ^'^  <A'i 

c  s    ■■'      \           ;• 

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\_ 

.BALOS  AND  AT  OCHOA;  ALSO  OF  THE  RIO  SAN   CARLOS  AT  3   MILES  ABOVE   ITS  MOUTH,  189a-18M. 


APPENDIX   111.— HYDROGRAPHIC   REPORT 


241 


RATING  TABLE  FOR  SAN  JUAN  RIVER  AT  OCHOA. 
This  table  is  applicable  only  from  January  1,  1899,  to  March  31,  1899. 


Qage 
heignt. 

Discharge. 

Gage 
height. 

Discharge. 

Gage 
height. 

Discharge. 

Gage 
height. 

Discharge. 

Feet. 

Second- ft. 

Feet. 

SecoDd-ft, 

Feet. 

Second-ft. 

Feet. 

Second-ft, 

6.7 

23,900 

7.6 

31,800 

9.5 

42,560 

11.4 

53,450 

5.8 

24,300 

7.7 

82,310 

9.6 

43,120 

11.5 

54,060 

6.9 

24,700 

7.8 

32  860 

9.7 

43,690 

11.6 

54,680 

6.0 

25,100 

7.9 

83,430 

9.8 

44,200 

11.7 

55,320 

6.1 

25,500 

8.0 

34,000 

9.9 

44,830 

11.8 

55,980 

6.3 

25,900 

8.1 

34,570 

10.0 

45,400 

11.9 

56,660 

6.3 

26,300 

8.2 

35,140 

10.1 

45,970 

12.0 

67,380 

6.4 

26,700 

8.3 

35,710 

10.2 

46,540 

12.1 

58,130 

6.5 

27,100 

8.4 

86,280 

10.3 

47,110 

12.2 

58,910 

6.6 

27,500 

8.5 

36,850 

10.4 

47,680 

12.3 

59,700 

6.7 

27,900 

8.6 

37,420 

10.5 

48,250 

12.4 

60,500 

6.8 

28,300 

8.7      . 

87,990 

10.6 

48,820 

12.5 

61,810 

6.9 

28,700 

8.8 

88,560 

10.7 

49,890 

12.6 

62,130 

7.0 

29,100 

8.9 

89,130 

10.8 

49,960 

12.7 

62,960 

7.1 

29,500 

9.0 

39,700 

10.9 

50,530 

12.8 

68,800 

7.2 

29,950 

9.1 

40,270 

11.0 

51,100 

12.9 

64,650 

7.8 

80,400 

9.2 

40,840 

11.1 

51,680 

13.0 

66,.500 

7.4 

30,850 

9.3 

41,410 

11.2 

52,260 

7.5 

81,300 

9.4 

41,980 

11.8 

62,850 

ESTIMATED  MONTHLY  DISCHARGE  OF  SAN  JUAN  RIVER  AT  OCHOA. 


Month. 


Discharge  in  Second-Feet. 


Maximum.    Minimum.    Mean. 


1898. 

January 76,200  32,240 

February 68,530  26,080 

March 30,650  20,140 

April 40,380  17,290 

May 34,880  16,300 

June 60,180  18,890 

July 78,050  85,540 

August 64,100  32,020 

September...  54,100  30,920 


45,250 
85,400 
23,800 
21,150 
19,640 
33,140 
46,810 
37,230 
39,530 


Total  for 

Month  in 

Acre- Feet, 


2,782,300 
1,966,000 
1,463,400 
1,258,  ,510 
1,207,600 
1,971,970 
2,878,200 
2,289,200 
2,362,200 

18,169,380 


Month. 


Discharge  in  Second-Feet. 

/ • — » 

Maximum.    Minimum.    Mean. 


Total  for 

Month  in 

Acre-Feet. 


1898. 

October 67,625 

November 107,000 

December 65,000 

Total  for  1898  . . 


Brought  forward,  18,169,380 
84,600  42,200  ^,,594,800 
87,080  51,890  3,087,670 
32,790         40,850         2,511,770 

..26,363,620 


1899. 

January 49,100 

February 41,120 

March.    81,300 


32,000  39,666  2,438,900 
29,840  32,540  1,807,180 
28,900         26,940         1,666,480 


16 


242 


NICARAGUA  CANAL  COMMISSION 


Rio  Machado. 

The  observer  at  Ochoa  also  made  occasional  measurements  of  the  discharge  of  the  Rio  Machado^ 
which  are  given  below: 

LIST  OF  DISCHARGE  MEASUREMENTS. 
Made  on  Rio  Machado  two  miles  above  its  mouth. 


Date. 

Hydrographer. 

Meter 
number. 

Gage 

height 

(feet). 

Area  of 

section 

(sq.  feet). 

Mean 
velocity  (ft. 
per  second). 

Discharge 
(second- 
feet). 

Remarks. 

1898. 
Mar.   3.. 

G.  R.  Wadlelgh.. 

1985 

5.34 

244 

0.59 

144 

«»     16.. 

**                         14 

1985 

5.10 

212 

0.57 

121 

Apr.    2 . 

((                         tt 

1985 

4.90 

221 

0.46 

102 

"       6.. 

((                         tt 

1985 

7.87 

400 

1.28 

514 

May  27.. 

t(                         tt 

1985 

5.20 

229 

0.60 

187 

Jun.    8.. 

tt                         tt 

1985 

6.32 

293 

0.94 

276 

•*     20.. 

tt                         tt 

1985 

7.66 

863 

0.76 

277 

»»     30.. 

tt                         tt 

1985 

7.72 

258 

1.12 

284 

New  Station,  1  mile 

July   9.. 
"     14.. 

It                         it 

it                         tt 

1985 
1985 

9.22 
7.11 

344 
230 

1.3^ 
1.06 

462 
244 

it 

"       [above. 

it 

*»     21.. 

tt                         tt 

1985 

8.86 

812 

1.37 

428 

tt 

it 

Aug.   8.. 

tt                         tt 

1985 

7.41 

238 

1.15 

267 

tt 

it 

"      5.. 

it                         it 

1985 

6.88 

203 

1.02 

208 

it 

it 

♦*     13.. 

....G.  H.  Williams.. 

1985 

7.06 

212 

1.09 

233 

it 

tt 

"     17.. 

it            tt 

1985 

6.74 

201 

1.02 

206 

tt 

ti 

"     19.. 

ft            it 

1985 

6.44 

185 

0.92 

170 

tt 

tt 

Sep.    5 . . 

tt            tt 

65 

5.80 

226 

0.65 

148 

Lower, 

or  Old  Station. 

"     24.. 

it            it 

65 

6.30 

167 

1.02 

170 

Upper 

Station. 

Oct.    6.. 

it            it 

65 

6.34 

163 

1.06 

172 

ft 

it 

»*     11.. 

it            it 

65 

5.83 

145 

0.89 

128 

it 

it 

**     19.. 

ft            it 

65 

6.08 

153 

0.87 

133 

it 

it 

Nov.   7 . . 

C.  Ilayman 

65 

5.48 

132 

0.79 

104 

It 

it 

**     15.. 

it        it 

65 

6.18 

160 

0.87 

139 

it 

ft 

"     21.. 

it         it 

65 

6.80 

196 

1.11 

218 

it 

it 

»*     29.. 

tt         tt 

65 

7.67 

250 

1.37 

343 

it 

it 

Dec.    7 . . 

tt         it 

65 

7.05 

213 

1.31 

279 

it 

ft 

"     17.. 

it         it 

65 

6.74 

190 

1.09 

208 

it 

tt 

"     27.. 

ft         tt 

65 

5.60 

143 

0.79 

113 

it 

it 

"     31.. 
1899. 
Jan.    2 . . 

....     **        ** 
H.  8.  Reed., 

65 
65 

5.73 
8.00 

146 
253 

0.87 
1.51 

127 
382 

it 
it 

it 
it 

"     10.. 

tt         tt 

65 

6.75 

193 

1.14 

221 

it 

it 

"     14.. 

tt         if 

65 

7.69 

246 

1.46 

361 

it 

it 

**     24.. 

....     **         ** 

65 

65 

6.57 
5.98 

189 

278 

1.02 
0.87 

192 
242 

it 
Lower 

it 

"     24.. 

it         it 

Station. 

**     31.. 
Feb.    6.. 

tt         it 
it         it 

65 
65 

5.78 
5.52 

155 
148 

0.78 
0.68 

121 
101 

Upper  Station. 

it            it 

»*     14.. 

....     **         ** 

65 

5.47 

144 

0.66 

95 

it 

"     17.. 

it         it 

65 

6.06 

171 

0.86 

147 

tt 

"     20.. 

tt         it 

65 

6.80 

177 

0.99 

176 

tt 

"     27.. 

tt         it 

65 
65 

5.40 
5.30 

140 
134 

0.67 
0.59 

93 
79 

tt 
tt 

Mar.    4 . . 

it         it 

»*     21.. 

tt         it 

65 

4.50 

204 

0.46 

93 

Lower  Station. 

"     30.. 

. .     '*         " 

65 

4.25 

186 

0.42 

77 

it 

it 

APPENDIX   III.— HYDROGRAPHIC   REPORT 


243 


Eio  Danta. 

This  stream  is  the  outlet  of  the  Florida  la- 
goon, and  flows  into  Kio  San  Juan  about  a  mile 
above  the  mouth  of  the  San  Francisco.  Its 
channel  is  narrow  and  deep,  and  contains  con- 
siderable fallen  timber,  but  is  not  subject  to 


sudden  changes  of  cross  section.  The  current  is 
usually  sluggish,  and  is  sometimes  affected  by  the 
stage  of  water  in  Rio  San  Juan. 

A  gage  was  established  on  February  28,  about 
IJ  miles  above  its  mouth,  and  the  following 
measurements  of  discharge  have  been  made: 


LIST  OF  DISCHARGE  MEASUREMENTS  MADE  ON  RIO  DANTA  1%  MILES 

ABOVE  MOUTH. 


Bate. 


Hydroffrapher. 


it 


t(     27 

July   8 ** 

*»    19 *» 

«*    28 " 

Aug.    8 ** 

**     18 *♦ 

"     28 *♦ 

Sep.    8 ** 

44       27 ** 

Oct.    8 A.  Ahrling. 


44 
«4 
44 
44 
44 
44 
44 
4i 
4i 


»«     18 " 

*«     29 ** 

Nov.   7 «» 

«*     18 ** 

i«     28 »* 

Dec.    8 ** 

«*     17 " 


44 
44 
44 
44 
44 
44 
44 


Meter      Qage  height 
number.         (feet). 


Area  of 
section 
(sq.  ft). 


;^S^.  5^s»- 


1898. 

Feb.  28 W.  W.  Schlecht 

Mar.   8 **  *' 

"     18 *' 

*»    28 " 

Apr.    9 »» 

"     28 ** 

JuD.  15 C.  Hay  man, 


98 

8.98 

134 

1.03 

188 

93 

8.22 

110 

0.82 

91 

93 

2.12 

82 

0.58 

47 

98 

2.97 

102 

0.86 

88 

98 

4.23 

148 

1.07 

159 

98 

2.24 

76 

0.70 

58 

98 

3.65 

80 

1.31 

106 

98 

7.45 

803 

1.08 

828 

98 

6.17 

195 

0.82 

161 

98 

5.11 

151 

0.59 

94 

98 

5.28 

165 

0.90 

149 

98 

4.63 

■  147 

0.80 

118 

98 

4.48 

135 

0.90 

121 

98 

4.21 

125 

0.84 

104 

93 

8.55 

94 

0.64 

60 

98 

6.08 

162 

0.60 

98 

98 

8.73 

108 

0.53 

67 

98 

5.65 

188 

0.12 

28 

98 

5.19 

156 

0.33 

52 

93 

4.01 

115 

0.86 

42 

98 

11.60 

432 

1.27 

549 

93 

7.18 

231 

0.82 

190 

93 

4.75 

142 

0.68 

82 

93 

5.99 

193 

0.87 

71 

Backwater  from  San  Juan. 


Kio  San  Fbancisco. 

The  Canal  Company's  project  provides  for  the 
construction  of  large  embankments  across  the 
valleys  of  the  Limpio,  Chanchos,  Nicholson,  San 
Francisco  and  Danta,  and  involves  the  control 
of  these  streams,  during  construction,  and  re- 
ceiving their  discharge  into  the  canal  after  com- 
pletion.    Their  permanent  control  is  also  nec- 


cssarv  if  the  canal  is  to  follow  the  San  Juan  val- 
ley.  A  knowledge  of  their  volume  and  fluctua- 
tions, as  well  as  of  the  rainfall  of  the  region,  is 
therefore  neeessarv. 

The  Rio  San  Francisco  has  its  source  on  the 
southwestern  slope  of  the  range  of  hills  known 
as  the  Eastern  Divide,  north  of  San  Juan  river. 
Its   principal   tributary  is  the   Rio  Chanchos, 


244 


NICARAGUA   CANAL  COMMISSION 


which  in  turn  receives  the  waters  of  Rio  Limpio. 
The  valley  of  the  San  Francisco  is  crossed  by  the 
proposed  upper  line  of  the  canal,  which  follows 
for  a  considerable  distance  the  valleys  of  the 
Chanchos  and  Limpio.  The  drainage  area  has 
never  been  definitely  outlined  and  only  meager 
information  exists  as  to  its  extent.  It  is  esti- 
mated, however,  at  about  65  square  miles.  The 
maximum  discharge  yet  observed  for  the  San 
Francisco  above  the  confluence  of  Nicholson 
creek  and  Eio  Chanchos  is  866  cubic  feet  per 
second.  A  discharge  of  888  cubic  feet  per 
second  has  been  obser\^ed  for  the  Chanchos  and 
100  for  Nicholson  creek.  This  would  indicate 
a  maximum  during  the  time  of  observation  of 
something  less  than  2000  for  the  San  Francisco 
at  its  mouth.  A  rough  tentative  estimate  based 
upon  these  figures  and  upon  the  greatest  rainfall 
probable  in  this  country  would  place  the  extreme 
maximum  discharge  which  can  occur  at  the 
mouth  of  the  San  Francisco  at  less  than  4000 
cubic  feet  per  second.  The  certainty  that  this 
figure  is  ample  is  greatly  strengthened  by  the 
nature  of  the  lower  portion  of  the  San  Fran- 


cisco drainage  basin,  which  includes  a  large  area 
of  perfectly  flat  land,  which  would  be  flooded  in 
case  of  a  discharge  of  3000  cubic  feet  per 
second  in  the  San  Francisco,  and  which  would  act 
as  a  storage  basin  for  floods  exceeding  that 
amount  until  they  could  be  discharged  through 
the  channel  of  the  river. 

San  Fran4^isco  Station. — On  January  2  a 
station  was  established  near  the  line  of  the  pro- 
posed canal,  about  two  miles  by  the  river,  above 
the  crossing  of  the  embankment  line,  and  above 
the  mouth  of  the  Canon  Surprise. 

On  February  21  a  gage  rod  was  placed  in  the 
river  at  the  crossing  of  the  embankment  line, 
and  thereafter  observations  were  taken  at  this 
point,  which  is  below  the  mouth  of  Caiion  Sur- 
prise. The  channel  is  narrow  and  deep,  is  com- 
posed of  hard  clay  and  is  not  subject  to  change. 

Measurements  are  given  below  for  both  sta- 
tions; rating  tables  have  been  constructed,  and 
daily  discharges  estimated  for  both,  which  are 
given  below.  Eainfall  and  hygrometer  obser- 
vations have  also  been  taken. 


LIST  OF  DISCHARGE  MEASUREMENTS  MADE  ON  RIO  SAN  FRANCISCO  AT  CENTER 

LINE  OF  CANAL. 


Date.             Hydrogrrapher. 

Meter 
number. 

Gage 
height 
(feet). 

Area  of 

section 

(sq.  feet). 

Mean 
velocity  (ft. 
per  second). 

Discharge 
(second- 
feet). 

Remarks. 

Jan.  19 W.  W. 

Schlecht. . . 

93 

18.52 

810 

1.02 

819 

Upper 

Station. 

"      23 " 

»' 

93 

15.12 

873 

1.19 

445 

tt 

**      25 •* 

... 

93 

11.97 

228 

0.91 

208 

ti 

Feb.    3 N.  P.  Leary 

93 

15 .  83 

407 

1.16 

471 

{( 

♦*      10 ** 

98 

12.75 

264 

0.88 

220 

ti 

**      20 «♦ 

"       

93 

10.60 

168 

0.74 

124 

it 

Mar.    2 W.  W. 

Schlecht. . . 

93 

10.86 

174 

0.74 

128 

it 

"      10 *« 

93 

11.78 

217 

0.85 

184 

it 

*«      19 »« 

93 

9.77 

180 

0.61 

80 

it 

**      29 

93 

10.26 

149 

0.68 

101 

ft 

Apr.    6 ♦' 

93 

15.90 

897 

1.54 

610 

it 

"        6 

93 

16.48 

429 

1.32 

569 

it 

"      20 " 

•  i 

93 

9.82 

134 

0.60 

81 

it 

"      30 

it 

•  *   • 

93 

C.86 

113 

0.59 

67 

it 

APPENDIX   III.— HYDROGRAPHIC   REPORT 


245 


Gage 

height. 


RATING  TABLE  FOR  RIO  SAN  FRANCISCO  AT  CENTER  LINE  OF  CANAL. 


Discharge. 


Gage 
height 


Discharge. 


Gage 
height. 


Discharge. 


liage 
height 


Discharge. 


Feet. 

Second-ft. 

Feet. 

Second-ft. 

Feet, 

Second-ft. 

Feet. 

Second-ft. 

8.6 

40 

10.8 

138 

13.0 

378 

15.3 

455 

8.7 

48 

10.9 

183 

13.1 

386 

15.8 

464 

8.8 

46 

11.0 

138 

13.3 

394 

15.4 

473 

8.9 

49 

11.1 

144 

13.3 

303 

15.5 

483 

9.0 

53 

11.3 

150 

13.4 

810 

15.6 

491 

9.1 

55 

11.8 

156 

13.5 

818 

15.7 

500 

9.3 

58 

114 

163 

13.6 

336 

15.8 

509 

9.3 

61 

11.5 

168 

13.7 

884 

15.9 

518 

9.4 

64 

11.6 

174 

13.8 

343 

16.0 

537 

9.5 

68 

11.7 

180 

18.9 

S60 

16.1 

536 

9.6 

73 

11.8 

186 

14.0 

358 

16.3 

545 

9.7 

76 

11.9 

198 

14.1 

366 

16.8 

554 

9.8 

80 

13.0 

300 

14.3 

374 

16.4 

568 

9.9 

84 

12.1 

307 

14.8 

383 

16.5 

573 

10.0 

88 

12.3 

314 

14.4 

390 

16.6 

581 

10.1 

98 

13.8 

333 

14.5 

898 

16.7 

590 

10.2 

98 

13.4 

330 

14.6 

406 

16.8 

599 

10.8 

103 

13.5 

338 

14.7 

414 

16.9 

608 

10.4 

108 

13.6 

346 

14.8 

433 

17.0 

617 

10.5 

113 

13.7 

354 

14.9 

430 

17.1 

636 

10.6 

118 

13.8 

363 

15.0 

438 

17.3 

635 

10.7 

123 

13.9 

370 

15.1 

446 

17.3 

644 

DAILY  GAGE  HEIGHT  OF  RIO  SAN  FRANCISCO  NEAR  LINE  OF  EMBANKMENTS  FOR  1898. 


Day. 


1. 

3 

8 


6, 
7. 
8. 
9. 
10. 

11, 
13. 
18. 
14. 
15. 


.Ian. 


15.30 
15.40 
15.85 
15.16 


13.85 
15.38 
14.35 
13.83 
14.10 

13.98 
13.83 
13.07 
11.65 


16 13.81 

17 

18 

19 

20 

21 

22 

23 

24 

25 

26 

27 

28 

29 

80 


13.95 
15.48 
13.53 
13.55 

13.31 
15.14 
13.55 

ii!99 

11.85 
13.05 
11.45 
11.60 
11.51 
81 1    11.20 


Feb. 


11.00 
14.91 
15.88 
15.61 
17.13 


10.51 
14.30 
14.41 
14.13 
13.75 

13.40 
12.10 
13.50 
11.70 
11.81 

11.03 
10.95 
10.84 
10.79 
10.60 

5.55 
5.44 
5.74 
5.31 
5.37 

5.88 
6.71 
8.86 


Mar. 


6.76 
6.13 
5.59 
5.41 
8.03 


8.33 
6.39 
6.07 
7.36 
7.60 

6.05 
5.00 
5.36 
5.11 
4.93 

4.83 
4.80 
4.68 
4.55 
4.47 

4.47 
4.59 
4.65 

4.48 
5.30 

6.46 
5.91 
6.35 
5.27 
4.89 
4.70 


Apr. 


4.58 
4.43 
4.29 
4.55 
10.27 


11.63 
8.05 
7.81 
6.38 
5.78 

5.61 
6.19 
5.59 
5.13 
4.91 

4.70 
4.54 
4.60 
4.80 
4.59 

4.35 
4.39 
5.76 
5.83 
4.75 

4.48 
4.79 
4.50 
4.38 
4.11 


Bfay. 


4.46 
5.66 
4.74 
4.64 

7.17 


6.54 
5.98 
5.07 
4.77 
4  63 

5.69 
6.93 
5.45 
4.96 
4.89 

5.87 
5.05 
5.56 
5.03 
8.07 

9.24 
9.79 
7.80 
6.67 
5.91 

5.45 
5.86 
5.37 
4.98 
5.48 
5.77 


Jun. 


7.34 
5.87 
5.33 
4.94 
4.73 


4.53 
4.63 
4.93 
5.06 
4.48 

4.61 
4.47 
7.04 
7.79 
6.36 

5.77 
5.33 
5.88 
8.93 
7.75 

9.83 
8.05 
7.54 
9.95 
11.63 

10.39 
11.38 
10.85 
11.83 
10.39 


July. 


9.85 
11.80 
13.43 
13.06 
12.37 


11.37 

9.46 

8.96 

10.83 

11.06 

10.95 
9.44 
8.65 
7.91 
7.48 

6.89 
6.77 
6.81 
8.60 
9.89 

11.03 

13.85 

10.37 

8.73 

9.03 

9.33 
8.49 
8.46 
8.04 
7.73 
7.65 


Aug. 


8.13 
9.75 
9.33 
8.39 

7.83 


7.50 
7.35 
8.69 
8.46 
8.63 

7.70 
8.35 
8.80 
10.83 
9.48 

8.50 
7.41 
7.31 
6.56 
6.48 

6.34 
6.38 
6.69 
7.14 
6.61 

6.70 
6.76 
6.64 
6.01 
5.77 
5.66 


Sept. 


5.96 
5.88 
5.56 
5.55 
5.29 


5.33 
5.84 
5.23 
5.36 
5.20 

8.90 

6.89 

11.44 

10.81 

8.59 

8.63 
7.70 
7.39 
6.44 
6.33 

6.49 
6.59 
11.46 
8.67 
7.47 

9.44 
7.93 
7.45 
6.56 
6.07 


Oct, 


Nov. 


6.19 
8.87 
6.88 
6.85 
6.50 


0.31 
5.i)5 
6.05 
6.47 
6.06 

5.73 
6.15 
6.96 
6.56 
5.82 

5.70 
5.68 
6.57 
9.18 
7.90 

7.40 
7.70 
7.38 
8.39 
7.50 

8.70 
8.30 
7.31 
6.60 


5.93 
5., 55 
5.34 
5.39 
5.46 


5.53 

7.15 

10.45 

8.48 

7.56 

7.33 
6.99 
8.86 
10.93 
9.65 

12.45 
15.43 
15.20 
13.47 
11.80 

10.23 
8.89 
8.16 
7.59 
7.66 

8.40 

9.55 

11.55 

11.47 


Dec. 


9.18 
9.33 
8.40 
7.86 
7.53 


7.70 
8.37 
7.40 
7.46 
9.10 

11.53 

10.65 

9.05 

7.90 

7.48 

7.03 
8.00 
7.48 
6.67 
6.35 

6.00 
5.83 
5.69 
5.50 
5.33 

5.43 
5.38 
5.84 


NoTB.— From  Jannary  3  to  February  30  inclnsiye,  rod  read  above  CafioD  Surprise.     On  February  30,  rod  moyed  to 
below  the  Cafion. 


NICARAGUA  CANAL  COMMISSION 


LIST  OF  DISCHAEQB  MEASUEEMBNT3  MADE  ON  RIO  SAN  PRANCISCO  AT  UNB  OF 
EMBANKMENTS. 


hei«ht 
(feet). 


Lower  St&tlon. 


APPENDIX   III.— HYDROGRAPHIC   REPORT 


247 


RATING  TABLE  FOR  RIO  SAN  FRANCISCO  AT  LINE  OF  EMBANKMENTS. 
This  table  is  applicable  only  from  February  24,  1898,  to  October  16,  1898. 


Gage  height. 

Discharge. 

Gage  height. 

Discharge. 

Gage  height. 

Discharge. 

Gage  height. 

Discharge. 

Feet 

Second-ft. 

Feet, 

Seoond-ft. 

Feet. 

Second-ft. 

Feet, 

Second-ft. 

4.0 

63 

6.5 

163 

•   9.0 

825 

11.6 

603 

4.1 

65 

6.6 

167 

9.1 

834 

11.6 

614 

4.2 

68 

6.7 

173 

9.2 

843 

11.7 

636 

4.3 

71 

6.8 

178 

9.8 

352 

11.8 

638 

4.4 

74 

6.9 

184 

9.4 

362 

11.9 

650 

4.5 

77 

7.0 

190 

9.5 

372 

12.0 

662 

4.6 

80 

7.1 

196 

9.6 

383 

12.1 

674 

4.7 

88 

7.2 

203 

9.7 

894 

12.2 

686. 

4.8 

86 

7.8 

208 

9.8 

405 

12.3 

698 

4.9 

89 

7.4 

214 

9.9 

416 

12.4 

710 

6.0 

98 

7.5 

220 

10.0 

427 

12.5 

733 

6.1 

97 

7.6 

226 

10.1 

438 

12.6 

734 

5.2 

101 

7.7 

232 

10.2 

449 

12.7 

746 

5.8 

105 

7.8 

238 

10.3 

460 

12.8 

768 

5.4 

109 

7.9 

244 

10.4 

471 

12.9 

770 

5.5 

113 

8.0 

250 

10.5 

482 

18.0 

783 

5.6 

117 

8.1 

257 

10.6 

494 

18.1 

794 

5.7 

123 

8.2 

264 

10.7 

506 

13.2 

806 

5.8 

137 

8.8 

271 

10.8 

518 

13.8 

818 

5.9 

132 

8.4 

278 

10.9 

530 

13.4 

880 

6.0 

187 

8.5 

285 

11.0 

542 

18.5 

842 

6.1 

142 

8.6 

298 

11.1 

554 

13.6 

854 

6.2 

147 

8.7 

801 

11.2 

566 

13.7 

866 

6.8 

152 

8.8 

809 

11.8 

578 

6.4 

157 

8.9 

317 

11.4 

590 

RATING  TABLE  FOR  RIO  SAN  FRANCISCO  AT  LINE  OF  EMBANKMENTS. 
This  table  is  applicable  only  from  Oct.  16,  1898,  to  November  30,  1898. 


Gage 
height. 

Discharge. 

Gage 
height. 

Discharge. 

Gage 
height. 

Disctiarge. 

Gage 
height 

Discharge. 

Feet. 

Second-ft. 

Feet. 

Seoond-ft. 

Feet. 

Second-ft. 

Feet 

Second-ft 

5.0 

40 

7.7 

188 

10.4 

360 

18.1 

556 

6.1 

45 

7.8 

189 

10.5 

867 

13.3 

564 

6.2 

50 

7.9 

195 

10.6 

874 

18.8 

573 

6.3 

65 

8.0 

201 

10.7 

881 

13.4 

580 

5.4 

60 

8.1 

207 

10.8 

888 

13.5 

688 

5.5 

65 

8.2 

218 

10.9 

895 

18.6 

596 

5.6 

70 

8.8 

219 

11.0 

402 

18.7 

604 

5.7 

76 

8.4 

225 

11.1 

409 

18.8 

613 

5.8 

80 

8.5 

231 

11.2 

416 

18.9 

630 

5.9 

85 

8.6 

237 

11.3 

428 

14.0 

638 

6.0 

90 

8.7 

248 

11.4 

430 

14.1 

636 

6.1 

95 

8.8 

249 

11.5 

437 

14.3 

644 

6.2 

100 

8.9 

255 

11.6 

444 

14.3 

652 

6.8 

105 

9.0 

262 

11.7 

451 

14.4 

660 

6.4 

110 

9.1 

269 

11.8 

458 

14.5 

668 

6.5 

115 

9.2 

276 

11.9 

465 

14.6 

676 

6.6 

120 

9.8 

283 

12.0 

472 

14.7 

684 

6.7 

125 

9.4 

290 

12.1 

479 

14.8 

692 

6.8 

180 

9.5 

297 

13.3 

486 

14.9 

700 

6.9 

185 

9.6 

304 

13.3 

493 

15.0 

708 

7.0 

141 

9.7 

811 

13.4 

500 

15.1 

716 

7.1 

147 

9.8 

818 

12.5 

508 

15.3 

734 

7.2 

153 

9.9 

825 

12.6 

516 

15.8 

782 

7.8 

159 

10.0 

882 

12.7 

634 

15.4 

740 

7.4 

165 

10.1 

839 

12.8 

533 

15.5 

748 

7.5 

171 

10.2 

846 

12.9 

540 

7.6 

177 

10.8 

853 

13.0 

548 

248 


NICARAGUA   CANAL  COMMISSION 


ESTIMATED  MONTHLY  DISCHAROES  OF  RIO  SAN  FRANCISCO  AT  LINE  OF  EHBANKMBNTS. 


Month.                  _Dl;KbargelnSo™nd-F«*t.^      ^oWl  in 

Month 

Dlichaive  in  Secirnd 

-Feet. 
Mean. 

^iSt. 

February  . 

March 

April   .... 

M«r 


Brought  forward,  72,000 

Jnly Setl  170  407  25,035 

August 54S  120  230  14,510 

Seylember 595  103  320  13,090 

October 313  75  163  9,980 

KoTcmher 745  57  379  18,000 

December  (1-3IS)  . .    005            105            333  13,940 

Total 104,135 


lit 


w'fflwniii 


lliiilr 


Diagram  of  dally  discharge  ot  the  Rio  San  Francisco  at  Embankment  Line. 


Kio  LiMPlO. 

On  JaDuaiy  6  a  gage  was  placed  on  the  left 
bank  of  the  limpio  about  200  yards  above  its 
mouth.  It  consists  of  a  vertical  plank  driven  in 
the  bed  of  the  stream,  and  spiked  to  a  tree  grow- 
ing in  the  bank. 

Three  60-penny  nails  driven  into  the  tree  to 
which  the  gage  is  fastened,  and  projecting  about 


one  inch,  mark  the  elevation  of  eleven  feet  above 
datum. 

Current  meter  measurements  were  made  from 
the  trunk  of  a  tree  felled  across  the  river. 

From  January  17  daily  observationa  were 
taken  at  this  point  until  February  20,  alter 
which  observations  were  taken  two  or  three 
times  per  month. 


APPENDIX   III.— HYDROGRAPHIC   REPORT 


249 


LIST  OF  DISCHARGE  MEASUREMENTS  MADE  ON  RIO  LIMPIO  NEAR  ITS  MOUTH. 


Date. 

1868. 

Hydrographer. 

Meter 
number. 

Gage 

height 

(feet). 

Area  of 
section 
(square  ft.). 

Mean  ve- 
locity (feet 
per  second). 

Discharge 

(second-         Remarks, 
feet). 

Jan. 

44 

31 

38 

3. . . . 

11 

19 

12 

23 

12 

23 

14.... 
24 

4.... 
14.... 
34. . . . 

3.... 
18.... 
38 

8.... 
13.... 
38.... 

8. . . . 
14.... 
33 

4 

18.... 
33 

3.... 
12.... 
14.... 
23.... 

3.... 
18.... 
37.... 

....H.  8. 
. . . .     ** 

. . . .     •* 
. . . .     ** 
. . . .     ** 
....      ** 

(4 
44 

.V..C.  H 

14 

.   .  .  .          ** 

44 

44 

44 
44 
44 
44 
44 
44 
«4 
44 
44 

!*.*.!Aif. 

44 

.  .  .  .          ** 

44 

44 

44 
44 
44 
(4 
44 

Keed 

44 

Stk.  3 
Stk.  3 

6.20 
4.27 
9.80 
4.76 
8.88 
4.08 
8.85 
4.05 
8.94 
3.80 
3.83 
3.60 
3.72 
3.45 
7.96 
4.11 
6.29 
5.42 
5.04 
4.20 
8.49 
6.02 
7.19 
4.38 
4.17 
4.60 
3.51 
3.93 
.5.24 
4.48 
4.60 
5.22 
3.51 

76 
84 

200 
42 
22 
30 
15 
30 
31 
25 
34 
32 
21 
16 

116 
20 
42 
53 
48 
84 
19 
46 

118 
34 
33 
41 
18 
80 
48 
87 
36 
46 
18 

1.31 
0.93 
0.39 
0.94 
1.15 
0.99 
1.14 
1.08 
1.05 
0.92 
1.10 
0.95 
0.89 
0.69 
0.52 
1.08 
1.05 
0.76 
1.10 
1.44 
1.28 
0.77 
0.32 
0.51 
0.56 
0.66 
0.88 
0.73 
0.79 
0.78 
1.08 
1.02 
0.88 

100 
82 

Feb. 

44 
44 

Mar. 

44 

Apr. 

44 

May 

44 

V.  Schlecht 

44 

44                  

44                   

44                   

44 
44 

ayman 

Stk.  3 
Stk.  3 
Stk.  3 
98 
93 
98 
98 
98 

78            Backwater. 

40 

25 

80 

17 

32 

22 

23 

44 

98 

25 

■Tnne 

44 

93 

22 

44 

(4 

93 

19 

44 

i4 

98 

11 

July 

44 

44 

98 

60 

(4 

98 

23 

44 

41 

98 

44 

Aug. 

44 

44 

98 

41 

4t 

93 

48 

44 

44 

93 

51 

Sep. 

44 

44 

93 

34 

44 

93 

35 

44 

44 

93 

88            Backwater. 

Oct. 

44 

Ahrling 

44               .   ,   . 

93 
93 

20 
18 

44 

44                                .... 

98 

29 

Nov. 

4( 

93 

16 

44 

44 

93 

23 

44 

44 

98 

38 

44 

4( 

93 

29 

Dec. 

44                                        ,    , 

93 

39 

44 

44 

93 

47 

^4 

44 

93 

16 

RATING  TABLE  FOR  RIO  LIMPIO  100  YARDS  ABOVE  ITS  MOUTH. 
This  table  is  applicable  only  from  January  6,  1898,  to  February  20,  1898. 


Gage 
height. 

Discharge. 

Gage 
height. 

Discharge. 

Gage 
height. 

Discharge. 

Gage 
height. 

Discharge. 

Feet. 

Second-ft. 

Feet. 

6econd-ft. 

Feet. 

Second-ft. 

Feet. 

Second-ft. 

2.9 

11 

4.7 

38 

6.5 

105 

8.8 

195 

3.0 

12 

4.8 

40 

6.6 

110 

8.4 

200 

3.1 

18 

4.9 

48 

6.7 

115 

8.5 

205 

8.2 

14 

6.0 

46 

6.8 

120 

8.6 

310 

8.3 

15 

5.1 

49 

6.9 

125 

8.7 

316 

8.4 

16 

5.3 

53 

7.0 

130 

8.8 

320 

3.5 

17 

5.3 

56 

7.1 

135 

8.9 

235 

8.6 

18 

5.4 

60 

7.2 

140 

9.0 

330 

8.7 

19 

6.5 

64 

7.8 

145 

9.1 

386 

3.8 

20 

5.6 

68 

7.4 

150 

9.2 

340 

3.9 

33 

5.7 

72 

7.5 

1.55 

9.3 

346 

4.0 

34 

5.8 

76 

7.6 

160 

9.4 

350 

4.1 

36 

5.9 

80 

7.7 

165 

9.5 

255 

4.2 

38 

6.0 

84 

7.8 

170 

9.6 

260 

4.8 

80 

6.1 

88 

7.9 

175 

9.7 

265 

4.4 

S3 

6.3 

92 

8.0 

180 

9.8 

270 

4.5 

84 

6.8 

96 

8.1 

185 

9.9 

275 

4.6 

86 

6.4 

100 

8.2 

190 

10.0 

380 

250 


NICARAGUA  CANAL  COMMISSION 


ESTIMATED  MONTHLY  DISCHARGE  OF  RIO  LIMPIO  100  YARDS  ABOVE  ITS  MOUTH. 


Month. 

Discharge  In  Second-Feet.       Total  in 
Maximum.    Minimum.    Mean. '^*^^^^®®** 

Month. 

Dischargre  in  Second-Feet.       Total  In 
Maximum.    Minimum.    Mean. -^°'^^®®*' 

Jannaryf  1898. 
(6-31) 

168             22             56             2,775 

February,  1898. 
(1  to20incl.). 

..     283               20               82           3,250 

Upper  Station  on  the  Rio  Chanchos. 

On  January  17  a  gage  was  placed  on  the  right 
bank  of  the  Chanchos,  about  200  yards  above 
the  mouth  of  Eio  Limpio.  It  consists  of  a  ver- 
tical pine  board,  marked  in  feet  and  tenths, 
driven  into  the  bed  of  the  stream  and  spiked  to 
a  tree  growing  in  the  bank.  Bench  mark  con- 
sists of  three  60-penny  nails  driven  in  the  tree 


to  which  gage  was  fastened,  at  13-foot  mark, 
projecting  about  three  inches.     Gagings  were 

made  bv  current  meter  from  the  trunk  of  a  tree 

t/ 

felled  across  the  stream. 

Daily  observations  were  taken  at  this  point 
until  Februarv  20,  after  which  observations  were 
taken  two  or  three  times  a  month. 


LIST  OF  DISCHARGE  MEASUREMENTS  MADE  ON  RIO  CHANCHOS  AT  UPPER  STATION. 

Remarks. 


Date. 

1896. 

Hydrographer. 

Meter 
number. 

Qage 
hei{?ht 
(feet). 

Area  of 

section 

(sq.  feet). 

Mean  ve- 
locity (feet 
per  sec.) 

Discharge 
(second- 
feet). 

Jan. 

21 

..H.  S. 

Reed 

Stk.  2 

6.07 

245 

0.92 

226 

it 

28.... 
0.  . .  • 

..W.  W 

ti 

Stk.  2 
Stk.  2 

2.65 
8.00 

90 
334 

0.48 
0.96 

43 

Feb. 

.  Schlecht  

321 

tt 

11..-. 

It 

Stk.  2 

3.30 

115 

0.64 

74 

ti 

19.... 

it 

Stk.  2 

2.26 

70 

0.53 

37 

Mar. 

12 

tt 

93 

2.54 

80 

0.62 

49 

C( 

23.... 

tt 

93 

1.67 

50 

0.46 

23 

Apr. 

12 

it 

93 

2.48 

78 

0.60 

47 

it 

28.... 

tt 

93 

2.50 

78 

0.60 

47 

May 

14 

.  .  C.  Havman 

93 

2.21 

66 

0.58 

38 

24.... 

4.... 

14 

24 

2.... 

13 

28 

3.... 
13.... 
28.... 

o.  .  .  . 

tt 
ti 
it 
it 
tt 
tt 
it 
tt 
ti 
tt 
tt 

tt 

93 
93 
93 
93 
93 
93 
93 
93 
93 
93 
93 

2.34 
1.78 
2.05 
1.92 
6.68 
2.60 
3.87 
4.10 
3.56 
2.21 
1.78 

76 

46 

52 

53 

243 

73 

121 

136 

112 

64 

46 

0.64 
0.46 
0.63 
0.55 
1.22 
0.63 
0.75 
0.89 
0.69 
0.65 
0.47 

48 

June 

tt 

22 

t( 

it 

38 

it 

it 

29 

July 

tt 

tt 

297 

tt 

46 

ii 

tt 

91 

Aug. 
it 

tt 

121 

ft 

77 

it 

it 

42 

Sept. 

ti 

\,'  • '  • 

23 

ti 

14. . . . 
28 

4.... 
13.... 
22. . . . 

2.... 
12. . . . 
14.... 
22.... 

8.... 
13.... 
27.... 

tt 
t( 
tt 
tt 
tt 

.  .      tt 
tt 
it 

, ,      it 
tt 
tt 
tt 

ti 

93 
93 
93 
93 
83 
93 
93 
93 
93 
93 
93 
93 

8.67 
6.05 
3.13 
2.88 
8.40 
2.00 
2.62 
3.91 
2.94 
3.12 
3.73 
1.89 

113 

230 

100 

91 

105 

55 

76 

115 

84 

92 

109 

54 

0.83 
1.13 
0.76 
0.80 
0.94 
0.50 
0.74 
0.95 
0.74 
0.86 
0.92 
0.50 

93 

it 

tt            

260 

Oct. 

tt 

76 

it 

it            

73 

it 

ft              ... 

98 

Nov. 

tt            ... 

28 

tt 

tt            

57 

tt 

tt 

109 

it 

tt        ^ 

62 

Dec. 

tt 

79 

it 

tt 

100 

tt 

tt    

27 

APPENDIX   III.— HYDROGRAPHIC   REPORT 


251 


RATING  TABLE  FOR  RIO  CHANCHOS  ABOVE  THE  LIMPIO. 
This  table  is  applicable  only  from  January  17,  1898,  to  February  21, 


1898. 


height. 


Dischargre. 


Gaffe 
leitrnl 


heigift. 


Discharge. 


Oage 
height. 


Discharge. 


Gage 
lioighl 


hoignt. 


Discharge. 


Feet. 

Second-feet. 

Feet. 

Second- feet. 

Feet. 

Second-feet. 

Feet. 

Second-feet. 

2.0 

31 

3.8 

104 

5.6 

212 

7.4 

820 

2.1 

83 

3.9 

no 

5.7 

218 

7.5 

326 

2.2 

35 

4.0 

116 

5.8 

224 

7.6 

332 

2.3 

38 

4.1 

122 

5.9 

230 

7.7 

838 

2.4 

41 

4.2 

128 

6.0 

236 

7.8 

844 

2.5 

44 

4.3 

134 

6.1 

242 

7.9 

350 

2.6 

47 

4.4 

140 

6.2 

248 

8.0 

356 

2.7 

51 

4.5 

146 

6.8 

254 

8.1 

362 

2.8 

55 

4.6 

152 

6.4 

260 

8.2 

868 

2.9 

59 

4.7 

158 

6.5 

266 

8.3 

374 

8.0 

63 

4.8 

164 

6.6 

272 

8.4 

880 

8.1 

67 

4.9 

170 

6.7 

278 

8.5 

386 

8.2 

72 

5.0 

176 

6.8 

284 

8.6 

392 

8.8 

77 

5.1 

182 

6.9 

290 

8.7 

398 

3.4 

82 

5.2 

188 

7.0 

296 

8.8 

404 

8.5 

87 

5.3 

194 

7.1 

302 

8.9 

410 

8.6 

93 

5.4 

200 

7.2 

308 

8.7 

98 

5.5 

206 

7.8 

314 

ESTIMATED  MONTHLY  DISCHARGE  OF  RIO  CHANCHOS  ABOVE  THE  LIMPIO. 

Month. 

Discharge  in  Second-Feet.        Total  In                       Month                     Discharge  in  Second-Feet. 
Maximum.    Minimum.    Meani  Acre-Feet.                         1»WJ.                  Maximum.    Minimum.    Mean! 

Total  in 
Acre-Feet. 

January 

17-31..         252                36             96          2,850                     February  1-20 .. .         895                34             139 

5,520 

Lower  Station  on  the  Rio  Chanchos. 

A  gage  was  placed  on  the  left  bank  of  the 
Rio  Chanchos,  about  one-half  mile  above  the 
point  where  the  telegraph  line  intersects  the 
river.  It  consists  of  a  vertical  pine  board  driven 
in  the  bed  of  the  stream,  and  spiked  to  a  tree 
growing  on  the  bank.     Bench  mark  consists  of 


two  8-penny  nails  driven  in  a  notch  in  a  tree,  25 
feet  from  the  river  bank  at  nearest  point  and 
30  feet  from  gage  rod.  Tree  has  one  smaller 
leaning  against  it. 

Measurements  of  discharge  were  made  from  a 
huge  tree  trunk  lying  across  the  river  one-half 
mile  up  stream  from  the  gage. 


LIST  OF  DISCHARGE  MEASUREMENTS  MADE  ON  RIO  CHANCHOS  AT  LOWER  STATION. 


Date. 
1808. 


Hydrogrraphor 


Meter 
number. 


Gage 
height 
(feet). 


Area  of 
section 
(sq.  ft.). 


Mean  ve- 
locity (ft. 
per  sec.). 


Discharge 
(second- 
feet). 


Remarkfi. 


Jan.   10 N.  P.  Leary  . . . 

♦*      20 W.  W.  Schlecht 


"  27, 
Feb.     2. 

"      10. 

«*  18. 
Mar.    7. 

**      17. 

"      26. 


98 

5.98 

821 

1.26 

404 

Stk.  2 

2.55 

199 

0.67 

134 

Stk.  2 

1.82 

167 

0.54 

90 

Stk.  2 

7.28 

455 

1.48 

674 

Stk.  2 

8.19 

204 

0.80 

162 

Stk.  2 

0.92 

144 

0.83 

48 

98 

1.16 

148 

0.56 

80 

93 

0.35 

125 

0.47 

58 

98 

0.78 

189 

0.48 

67 

252 


NICARAGUA  CANAL  COMMISSION 


LIST  OF  DISCHARGE  MEASUREMENTS  MADE  ON  RIO  CHANCHOS  AT  LOWER  STATION.— Cont. 


Date. 

Hydrographer. 

Meter 
Dumber. 

Gage 
height 

Area  of 
section 

Mean  ve- 
locity (ft. 

Discharge 
(second- 

1806. 

(feet). 

(sq.  ft.). 

per  sec). 

feet). 

Apr.    7 

.W.  W.  Schlecht 

93 

2.15 

169 

0.65 

109 

"      16 

it 

■  •                                                          •   •  •   • 

93 

0.16 

128 

0.37 

46 

May    7 

.C.  Hayman 

93 

1.17 

124 

0.57 

71 

**      80 

93 

0.22 

115 

0.39 

45 

June   8 

98 

0.05 

94 

0.33 

32 

**      17 

93 

0.18 

107 

0.31 

33 

**      29 

95 

5.78 

264 

0.84 

228 

July    7 

93 

3.70 

201 

0.68 

188 

*»      16 , 

93 

1.51 

127 

0.40 

51 

"      27 

93 

3.01 

184 

0.70 

130 

Aug.    6 

98 

2.46 

154 

0.62 

97 

**      17 

93 

2.00 

146 

6.46 

67 

**      27 

93 

1.06 

102 

0.57 

58 

Sept.  7 

93 

0.55 

89 

0.51 

45 

»»      17 

93 

2.89 

137 

0.47 

63 

"      26 

93 

2.53 

123 

0.47 

58 

Oct.     7 

.A.  Ahrling 

93 

1.03 

103 

0.50 

51 

**      10 

98 

1.15 

99 

0.53 

58 

»»      18 

93 

1.78 

111 

0.41 

46 

»»      26 

93 

8.74 

169 

0.61 

103 

Nov.    6 

93 

0.79 

95 

0.36 

84 

«*      14 

93 

5.88 

255 

0.62 

159 

*»      16 

93 

7.43 

854 

1.41 

498 

**      26 

93 

2.80 

155 

0.72 

111 

Dec.     7 

93 

3.07 

168 

0.78 

131 

»*      17 

93 

2.90 

148 

0.62 

92 

*«      28 

93 

0.83 

99 

0.47 

47 

Remarks. 


RATING  TABLE  FOR  RIO  CHANCHOS   AT  LINE  OF  EMBANKMENTS. 
This  table  is  applicable  only  from  January  7,  1898,  to  October  31,  1898. 


Gage 
height. 

Discharge. 

Gage 
height. 

Discharge. 

Gage 
height. 

Discharge. 

Gage 
height. 

Discharge. 

Feet. 

Second-ft. 

Feet. 

Second-ft. 

Feet. 

Second-ft. 

Feet. 

Second-ft. 

-1.0 

9 

1.4 

72 

8.8 

170 

6.2 

448 

-0.9 

11 

1.5 

75 

3.9 

175 

6.3 

470 

-0.8 

13 

1.6 

78 

4.0 

181 

6.4 

492 

-0.7 

15 

1.7 

81 

4.1 

187 

6.5 

514 

-0.6 

18 

1.8 

84 

4.2 

198 

6.6 

536 

-0.5 

21 

1.9 

87 

4.3 

200 

6.7 

558 

-0.4 

28 

2.0 

90 

4.4 

207 

6-8 

580 

-0.8 

26 

2.1 

94 

4.5 

215 

6.9 

602 

-0.2 

28 

2.2 

98 

4.6 

223 

7.0 

624 

-0.1 

81 

2.8 

102 

4.7 

282 

7.1 

646 

0.0 

33 

2.4 

106 

4.8 

241 

7.2 

668 

0.1 

85 

2.5 

110 

4.9 

251 

7.8 

690 

0.2 

87 

2.6 

114 

5.0 

261 

7.4 

712 

0.8 

39 

2.7 

118 

5.1 

272 

7.5 

734 

0.4 

42 

2.8 

122 

5.2 

283 

7.6 

756 

0.5 

45 

2.9 

126 

5.8 

295 

7.7 

778 

0.6 

48 

8.0 

130 

5.4 

308 

7.8 

800 

0.7 

51 

3.1 

135 

5.5 

822 

7.9 

822 

0.8 

54 

8.2 

140 

5.6 

837 

8.0 

844 

0.9 

57 

8.3 

145 

5.7 

853 

8.1 

866 

1.0 

60 

3.4 

150 

5.8 

870 

8.2 

888 

1.1 

68 

8.5 

155 

5.9 

388 

1.2 

66 

8.6 

160 

6.0 

407 

1.3 

69 

3.7 

165 

6.1 

427 

• 

APPENDIX   III.— HYDROGRAPHIC   REPORT 


253 


ESTIMATED  MONTHLY  DISCHARGE  OF  RIO  CHANCHOS  AT  LINE  OF  EMBANKMENTS. 


Discharge  in  Second-Feot.       Total  in 

Month.  / • ^  Ai'T«-P«^f 

Maximum.    Minimum.    Mean. -^*''®^' *^^- 

1898. 

January 670  57  181  11,130 

February 624  43  188  10,440 

March 73  82  53  8,260 

April 582  26  102  6,070 

May 80  88  59  8,630 

June 370  28  101  6,010 

40,540 


DiBchargo  in  gecond-Feet.       ^otal  in 

Month.  4 » V   A«i^c^l^* 

Maximum.    Minimum.    Mean. '^*'^^'®®^ 

1898.  Brought  forward,  40,540 

July 888  71  228  14,020 

August 168  46  95  5,840 

September 585  85  138  8,210 

October 145  46  88  5,410 

November 755  84  182  10,830 

December 390  40  130  7,990 

Total 92,840 


NiciioLsox  Creek. 

On  January  17  a  gage  rod  was  placed  in  Xich- 
olson  creek  a  short  distance  below  the  telegraph 
line,  and  the  following  measurements  of  dis- 
charge were  made,  which  give  a  fair  idea  of  the 


size  of  the  stream  and  its  fluctuations.  It  will 
be  noted  that  the  relation  between  gage  height 
and  discharge  is  disturbed  by  back  water  in  the 
San  Francisco,  but  this  does  not  affect  the  accu- 
racy of  the  measurements  given. 


LIST  OF  DISCHARGE  MEASUREMENTS  MADE  ON  NICHOLSON  CREEK  BELOW 

TELEGRAPH  LINE. 


Date. 

1M«. 

Hydrographer. 

Meter 
number. 

Jan.    21 . . . 

...N.  P.  Leary 

93 

"       28... 

(t          

93 

Feb.    15... 

{ 

(          

Schlecht 

93 

**      21... 

...W.  Vi. 

93 

Mar.     6... 

•  •   ■                                                            •   •  •  < 

93 

**       15... 

•  •   •                                                                     •    •   •   < 

93 

»♦      25... 

. . . « 

it 

•   •  • 

93 

Apr.   15... 

93 

"       25... 

it 

•  •    •                                                                   •    •    •    I 

93 

May      7... 

..  .0.   Ilayman 

93 

**       18... 

I 

93 

"       80... 

93 

June     8. . . 

93 

*«       17... 

93 

**       29... 

98 

July    6... 

. . .          ** 

93 

"       14... 

98 

»*      26... 

98 

Aug.     6 . . . 

93 

"       15... 

93 

"       25... 

98 

Sept.    5. . . 

93 

**       15... 

93 

**       24... 

1 

93 

Gage  Area  of  Mean  velocity 

height  section  (feet 

(feet).         (square  feet).       per  second). 


Discharge 
(second- 
feet). 


Remarks. 


8.67 
5.80 
5.64 
5.02 
6.25 
4.60 
4.70 
4.46 
4.30 
5.80 
4.64 
4.82 
4.88 
4.72 
9.52 
9.  .52 
6.85 
7.50 
6.73 
8.22 
5.72 
4.91 
7.20 
8.00 


149 
57 
53 
34 
67 
17 
24 
21 
18 
35 
21 
31 
15 
22 

176 

158 
70 
87 
68 

104 
41 
21 
78 

100 


0.67 
0.56 
0.56 
0.69 
0.54 
0.81 
0.85 
0.82 
0.74 
0.66 
0.72 
0.65 
0.64 
0.63 
0.48 
0.45 
0.36 
0.49 
0.61 
0.42 
0.52 
0.54 
0.32 
0.38 


100 
32 
30 
24 
36 
14 
21 
17 
13 
24 
16 
20 
10 
13 
84 
71 
25 
43 
41 
43 
22 
11 
25 
38 


254 


NICARAGUA  CANAL  COMMISSION 


Rio  Sarapiqui. 

The  plan  of  canalizing  the  Kio  San  Juan,  as 
sometimes  proposed,  involves  the  control  of  the 
waters  of  Eio  Sarapiqui  and  of  the  sediment 
which  it  brings  down  from  the  mountains  of 
Costa  Kica. 

On  July  23  a  gage  was  placed  on  the  left  bank 
of  this  river  about  five  miles  above  its  mouth. 
It  is  a  vertical  rod,  graduated  to  feet  and  tenths, 


from  zero  to  13  feet,  and  spiked  to  a  tree  which 
hangs  over  the  river.  Another  rod,  graduated 
from  10  to  23  feet,  is  fastened  to  a  tree  about 
300  yards  up  stream,  on  the  same  side  of  the 
river.  At  this  latter  place  a  galvanized  steel 
cable  is  placed  across  the  river,  from  which 
measurements  of  discharge  are  made  with  the 
use  of  a  boat,  and  observations  of  sediment  car- 
ried are  also  made. 


LIST  OF  DISCHARGE  MEASUREMENTS  MADE  ON  RIO  SARAPIQUI  FIVE  MILES  ABOVE 

ITS  MOUTH. 


Date. 

1806. 


Hydrographer. 


Meter 
number. 


Oage 

hei^t 

(feet). 


Area  of 

section 

(square  ft.). 


Mean  ve- 
locity (feet 
per  second). 


Discharfire 
(second- 
feet). 


Remarks. 


it 
t( 

n 

(t 
ii 
it 


May   10. 

July  12. 

**       27. 

Aug.  27. 

"       81. 

Sep.     S. 

9. 

12. 

13. 

14. 

21. 

24. 

27. 
Oct.  11. 
Dec.   21. 

1899. 

Jan.     9. 

i( 

it 
it 
it 

it 
it 

Feb. 

it 

it 
it 
it 
it 
it 
it 

Mar. 
it 

it 

it 

it 

it 

it 
it 


..  .A.  P.  Davis, 


ti 


...G.  R.  Wadleigh 
. . .  W.  A.  Smith  . . 


it 


ti 


13. 
16. 
21. 
25. 
28. 
31. 

8. 

8. 
11, 
18. 
14. 
20. 
21. 
24. 

4. 

8. 
11, 
16. 
18. 
22. 
25. 
29. 


.n.  W.  Durham 


it 

ii 

ti 

•  it 

it 
ti 
it 
it 


it 
it 
it 
it 
ti 
ti 
it 
ti 
ti 
ti 
it 
it 
it 
it 
ti 
it 
it 
it 
it 
it 
it 
it 
it 


94 

94 
1985 
1985 
1985 
1985 
1985 
1985 
1985 
1985 
1985 
1985 
1985 
1985 
1985 


1985 
1985 
1985 
1985 
1985 
1985 
1985 
1985 
1985 
1985 
1985 
1985 
1985 
1985 
1985 
1985 
1985 
1985 
1995 
1985 
1985 
1985 
1985 


8.84 

8.51 

8.11 

8.25 

7.52 

8.98 

12.99 

13.06 

8.57 

8.72 

13.02 

11.95 

8.13 


9.00 

12.58 

13.30 

8.90 

8.83 

7.80 

7.35 

7.25 

7.25 

7.04 

18.40 

1.5.20 

11.20 

8.78 

11.37 

8.35 

11.88 

7.50 

7.68 

7.38 

6.81 

6.73 

10.00 


1,046 
3,686 
2,238 
1,922 
1,765 
1,823 
1,617 
2,088 
4,294 
4,054 
1,925 
1,972 
4,181 
3,388 
1,735 


1,979 
3,445 
8,703 
2,008 
2,015 
1,646 
1,461 
1,406 
1,450 
1,399 
5,563 
4,459 
2,869 
1,938 
2,967 
1,732 
2,882 
1,462 
1,561 
1,458 
1,284 
1,230 
2,475 


2.92 
2.65 
2.85 
2.43 
2.28 
2.34 
2.10 
2.38 
3.47 
3.43 
2.37 
2.40 
8.69 
3.42 
2.34 


2.52 
3.29 
8.42 
2.45 
2.43 
2.17 
2.10 
2.04 
2.03 
1.94 
4.81 
8.79 
2.99 
2.32 
2.96 
2.31 

3.11 
2.19 
2.18 
2.09 
1.87 
1.82 
2.75 


3,050 

10,762 

5,252 

4,677 

4,014 

4,264 

3,399 

4,974 

14,914 

13,898 

4,560 

4,730 

15,241 

11, .598 

4,053 

4,987 
11,348 
12,669 
4,920 
4,905 
3,582 
3,072 
2,862 
2,943 
2,711 
26,731 
16,892 
8,582 
4,501 
8,780 
4,007 
8,972 
3,198 
3,409 
8,040 
2,313 
2,240 
6,807 


APPENDIX   III.— HYDROGRAPHIC   REPORT 


255 


RATING  TABLE  FOR  RIO  SARAPIQUI  AT  STATION  FIVE  MILES  ABOVE  ITS  MOUTH. 
This  table  is  applicable  only  from  July  23,  1898,  to  January  1,  1899. 


Gage 
height. 

Discharge. 

Gage 
height 

Discharge. 

Gage 
height. 

Feet. 

Discharge. 
Second- feet. 

Gage 

height. 

Feet. 

Discharge. 

Feet. 

Second-feet. 

Feet. 

Second-feet. 

Second-feet 

7.2 

3,140 

9.7 

7,090 

12.2 

12,590 

14.7 

18,090 

7.8 

3,210 

9.8 

7,310 

12.3 

12,810 

14.8 

18,310 

7.4 

3,280 

9.9 

7,530 

12.4 

13,080 

14.9 

18,530 

7.5 

3,3.50 

10.0 

7,750 

12.5 

13,250 

15.0 

18,750 

7.6 

3,420 

10.1 

7,970 

12.6 

13,470 

15.1 

18,970 

7.7 

3,500 

10.2 

8,190 

12.7 

13,690 

15.2 

19,190 

7.8 

3,590 

10.3 

8,410 

12.8 

13,910 

15.3 

19,410 

7.9 

3,690 

10.4 

8,630 

12.9 

14,130 

15.4 

19,630 

8.0 

3,800 

10.5 

8,850 

18.0 

14,350 

15.5 

19,850 

8.1 

3,930 

10.6 

9,070 

13.1 

14,570 

15.6 

20,070 

8.2 

4,070 

10.7 

9,290 

13.2 

14,790 

15.7 

20,290 

8.3 

4,220 

10.8 

9,510 

18.3 

15,010 

15.8 

20,510 

8.4 

4,380 

10.9 

9,730 

13.4 

15,230 

15.9 

20,730 

8.5 

4,5.50 

11.0 

9,950 

13.5 

15,450 

16.0 

20,950 

8.6 

4,730 

ll.l 

10,170 

13.6 

15,670 

16.1 

21,170 

8.7 

4,920 

11.2 

10,390 

18.7 

15,890 

16.2 

21,390 

8.8 

5,120 

11.3 

10,610 

18.8 

16,110 

16.3 

21,610 

8.9 

5,380 

11.4 

10,830 

18.9 

16,380 

16.4 

21,880 

9.0 

5,550 

11.5 

11,050 

14.0 

10,5.50 

16.5 

22,050 

9.1 

5,770 

11.6 

11,270 

14.1 

16,770 

16.6 

22,270 

9.2 

5,990 

11.7 

11,490 

14.2 

16,990 

16.7 

22,490 

9.3 

6,210 

11.8 

11,710 

14.3 

17,210 

16.8 

22,710 

9.4 

6,430 

11.9 

11,930 

14.4 

17,430 

16.9 

22,930 

9.5 

6,650 

12.0 

12,150 

14.5 

17,650 

9.6 

6,870 

12.1 

12,370 

14.6 

17,870 

RATING  TABLE  FOR  RIO  SARAPIQUI  AT  STATION  FIVE  MILES  ABOVE  ITS  MOUTH. 
This  table  is  applicable  only  from  January  1.  1899.  to  March  31.  1899. 


Garo 
height 

Discharge. 

Gage 
height 

Discharge. 

Gage 
height. 

Discharge. 

Gage 
height 

Discharge. 

Feet 

Second-feet 

Feet 

Second-feet 

Feet 

Second-feet 

Feet 

Second-feet. 

6.5 

2,020 

8.0 

4,560 

10.7 

7,785 

12.8 

11,690 

6.6 

2,140 

8.7 

4,700 

10.8 

7,940 

12.9 

11,890 

6.7 

2,260 

8.8 

4,850 

10.9 

8,100 

18.0 

12,090 

6.8 

2,380 

8.9 

5,000 

11.0 

8,260 

18.1 

12,290 

6.9 

2,500 

9.0 

5,1.50 

11.1 

8,480 

13.2 

12,490 

7.0 

2,620 

9.1 

5,300 

11.2 

8,000 

13.3 

12,690 

7.1 

2,740 

9.2 

5,450 

11.8 

8,780 

13.4 

12,890 

7.2 

2,860 

9.3 

5,600 

11.4 

8,960 

13.5 

13,090 

7.8 

2,980 

9.4 

5,750 

11.5 

9,140 

13.6 

13,290 

7.4 

3,100 

9.5 

5,  WO 

11.6 

9,330 

13.7 

13,490 

7.5 

3,220 

9.6 

ti,060 

11.7 

9,520 

13.8 

13,690 

7.6 

3,840 

9.7 

6,220 

11.8 

9,710 

13.9 

13,890 

7.7 

8,460 

9.8 

6,380 

11.9 

9,900 

14.0 

14,090 

7.8 

8,580 

9.9 

6,  .540 

12.0 

10,090 

14.1 

14,290 

7.9 

8,700 

10.0 

6,700 

12.1 

10,290 

14.2 

14,.500 

8.0 

8,820 

10.1 

6,855 

12.2 

10,490 

14.3 

14,720 

8.1 

8,940 

10.2 

7,010 

12.3 

0,690 

14.4 

14,840 

8.2 

4,060 

10.3 

7.165 

12.4 

0,890 

14.5 

15,170 

8.8 

4,180 

10.4 

7,320 

12.5 

1,090 

14.6 

15,400 

8.4 

4,805 

10.5 

7,475 

12.6 

1,290 

8.5 

4,430 

10.6 

7,630 

12.7 

11,490 

256 


NICARAGUA  CANAL  COMMISSION 


ESTIMATED  MONTHLY  DISCHARGE  OF  RIO  SARAPIQUI  FIVE  MILES  ABOVE  ITS  MOUTH. 

Drainage  area.  1,100  square  miles,  approximately. 


Month. 


Discharflre  in  Second-feet. 


Maximum. 


Minimum. 


Mean. 


Total  for  the 
month  in 
acre-feet. 


Run-off. 


Depth 
in  inches. 


Seoond-feet 
per  sq.  mile. 


1898.     . 

July  (33-31) 

August  (1-5  and  18-31  Incl.) 

September 13,140 

October 14,570 

November 80,000 

December 21,610 

1809. 

January 18,580 

February 27,100 

March 8,960 


3,360 
4,100 
4,640 
3,150 

3,000 
2,710 
2.280 


5,890 
5,.550 
5,890 
8,240 
11,700 
6,650 

5,420 
5,300 
8,350 


841,250 
850,780 
507,500 
696,200 
408,890 

883,260 
288,800 
205,980 


5.83 
5.97 
8.65 
11.87 
6.98 

5.68 
4.93 
3.98 


5.05 
5.85 
7.50 
10.64 
6.05 

4.98 
4.78 
8.45 


Eio  Tauba. 

The  waters  of  the  San  Juan  river  have  two 
principal  outlets,  the  southern  called  the  Rio 
Colorado,  and  the  northern,  called  the  lower 
San  Juan.  The  latter  stream  sends  out  another 
distributary  which  empties  into  the  ocean  be- 
tween the  two  larger,  and  is  called  the  Taura. 
It  seems,  however,  that  a  portion  of  the  course 
of  the  Taura  is,  during  the  season  of  low  water, 
higher  than  the  water  in  the  San  Juan,  and  be- 
comes a  tributary  of  the  latter.  It  was  visited 
on  May  6, 1898,  and  was  at  that  time  discharging 
25  cubic  feet  per  second  into  the  San  Juan.  On 
the  same  day  the  discharge  of  the  San  Juan 
below  the  Taura  was  1112  cubic  feet  per  second. 
The  discharge  at  Ochoa  on  the  same  date  was 
16,950  cubic  feet  per  second. 

On  July  13  the  Taura  was  flowing  away  from 
the  San  Juan  and  its  volume  200  yards  below  its 
exit  was  2234  cubic  feet  per  second.  On  this 
day  the  discharge  of  the  San  Juan  at  Ochoa  was 
46,000  cubic  feet  per  second. 

The  condition  in  May  of  the  Taura  flowing 
toward  the  San  Juan  was  apparently  quite  anom- 
alous, the  mouth  at  the  coast  being  closed  by  a 
dike  of  sand  built  by  the  waves.  The  normal 
condition  of  the  Taura  is  that  of  a  minor  dis- 
tributary of  the  San  Juan. 


Rio  Deseado. 

This  is  a  small  stream  rising  in  the  ridge  of 
hills,  known  in  canal  literature  as  the  "  Eastern 
Divide." 

According  to  the  company's  location  the  canal 
is  to  follow  the  valley  of  the  Deseado  for  a  con- 
siderable distance  and  the  plan  involves  the  con- 
trol and  diversion  of  the  waters  of  this  stream. 
Three  locks  and  several  high  embankments  are 
to  be  constructed  in  this  valley  and  the  volume 
of  the  river  and  the  amount  of  rainfall  in  this 
vicinity  become  important  facts,  an  approximate 
knowledge  of  which  is  necessary  to  an  intelligent 
discussion  of  plans  and  estimate  of  cost. 

On  the  25th  of  December,  1897,  a  gage  was 
placed  in  the  Deseado  at  a  point  about  five  miles 
above  its  mouth,  measured  along  the  course  of 
the  stream;  a  rain  gage  was  also  established  at 
this  point,  and  observations  of  river  height,  rain- 
fall, temperature  and  humidity  were  begun  by 
Mr.  W.  M.  Barton. 

Subsequent  measurements  of  discharge  showed 
that  no  definite  relation  could  be  established  be- 
tween gage  height  and  discharge  of  the  stream, 
although  the  channel  consists  of  hard  clay  and  is 
not  changeable.  The  erratic  changes  in  velocity 
which  the  stream  exhibited  at  this  point  are 
doubtless  due  to  the  fact  that  it  runs  through 


APPENDIX   III.— HYDROGRAPHIC   REPORT 


257 


swampy  country  on  very  flat  slope.  Though 
there  are  no  definite  tributaries  anywhere  near 
the  gaging  station,  yet  heavy  rains  in  the  swamps 
serve  to  back  the  water  in  the  Deseado,  if  occur- 
ring below  the  station,  and  to  accelerate  its  ve- 
locity if  occurring  above. 

On  March  4  observations  of  gage  height  were 


begun  some  distance  above  at  "  Camp  No.  7  " 
near  the  site  of  the  proposed  Lock  No.  1,  and  the 
following  discharge  measurements  were  made  at 
that  point,  and  from  these  a  rating  table  was 
constructed  and  the  table  of  discharges  esti- 
mated. 


LIST  OF  DISCHARGE  MEASUREMENTS  MADE  ON  RIO  DESEADO  AT  CAMP  BARTON. 


Date, 
laoft 

Hydrofirrapher. 

Moter 
niiiiibf*r 

Gage 
height 

Area  of 
section 

Mean  ve- 
locity (ft. 

Dlschanpe 
(second- 

(feet). 

(sq.  ft.). 

per  sec.). 

feet). 

Peb. 

26 

.A.  P.  Davis 

Stk.  3 

7.85 

772 

0.63 

489 

Mar. 

8 

.  W.  M.  Barton 

2 

8.70 

823 

0.13 

99 

tt 

15 

.L.  E.  Lannan 

2 

7.71 

711 

0.03 

19 

April 

5 

3 

7.69 

730 

0.63 

462 

ti 

13 

2 

8.03 

744 

0.12 

97 

tt 

21 

2 

4.85 

507 

0.06 

84 

tt 

36 

3 

5.75 

575 

0.10 

61 

May 

3 

2 

6.38 

608 

0.18 

107 

it 

7 

2 

7.13 

671 

0.14 

92 

tt 

13 

2 

6.68 

634 

0.35 

218 

it 

18 

3 

5.68 

570 

0.05 

31 

it 

24 

.J.  C.  Elson 

3 

6.83 

639 

0.09 

58 

it 

31 

2 

6.33 

609 

0.36 

330 

June 

3 

3 

6.80 

625 

0.06 

43 

tt 

11 

3 

4.90 

491 

0.07 

85 

it 

14 

3 

7.15 

663 

0.23 

156 

it 

16 

3 

7.38 

649 

0.15 

103 

it 

20 

3 

6.80 

636 

0.06 

48 

it 

35 

3 

10.12 

922 

0.68 

634 

it 

38 

3 

10.26 

928 

0.18 

173 

July 

8 

3 

10.80 

958 

0.22 

311 

it 

13 

2 

10.15 

919 

0.23 

319 

tt 

16 

2 

8.88 

822 

0.19 

159 

tt 

21 

3 

11.83 

1026 

0.53 

550 

Aug. 

6 

2 

10.19 

918 

0.22 

308 

it 

9 

3 

10.59 

936 

0.38 

809 

it 

13 

3 

10,51 

933 

0.14 

185 

tt 

16 

2 

10.95 

891 

0.10 

98 

it 

26 

3 

7.43 

681 

0.14 

100 

Sept. 

2 

3 

6.70 

616 

0.07 

45 

it 

10 

3 

6.15 

577 

0.05 

37 

it 

14 

3 

7.19 

657 

0.37 

343 

tt 

19 

3 

6.66 

610 

0.11 

69 

tt 

24 

3 

6.60 

601 

0.10 

63 

Oct. 

6 

2 

6.10 

560 

0.13 

71 

it 

10 

3 

6.78 

597 

0.09 

56 

it 

15 

2 

6.94 

603 

o.io 

64 

tt 

22 

2 

6.99 

633 

0.24 

151 

it 

26 

2 

8.60 

738 

0.27 

•    199 

it 

31 

2 

7.69 

668 

0.07 

46 

Nov. 

10 

2 

9.30 

788 

0.14 

111 

it 

16 

2 

11.78 

950 

0.45 

439 

tt 

Xo. . • . < 

2 

14.28 

1153 

0.50 

577 

it 

23 

2 

11.61 

940 

0.15 

144 

it 

26 

2 

11.06 

913 

0.35 

817 

it 

29 

k              4  4 

2 

12.49 

1030 

0.31 

819 

Dec. 

1 

2 

12.26 

1004 

0.36 

364 

it 

8 

3 

11.18 

936 

0.24 

339 

tt 

13 

3 

12.33 

1012 

0.23 

383 

17 


268  NICARAGUA  CANAL  COMMISSION 

LIST  OP  DISCHARGE  MBASDREMBNTS  MADE  ON  RIO  DESEADO   AT  CAMP  NO.  7. 


]^^^'  Hydrograpber 


(lEt  ft.). 


Mean  ve- 
locity (ft 


Dlacham 
feet). 


3.% 

April 

1 

fi 

■;: 

IN 

a-i 

May 

fl 

33 

30 

jQDe 

0 

13 

31 

Jnl, 

11 

A  eg. 

Vi 

as 

Sept. 

1) 

IB 

26 

Oct. 

'^I'.'.W'.'. 

10 

IT 

Sot. 

■•9 

11 

15.... 

Dec, 

art 

13 

Ifl 

19 

APPENDIX   III.— HYDROGRAPHIC   REPORT 


259 


This 


RATING  TABLE  FOR  RIO  DESEADO  AT  CAMP  NO.  7. 
table  is  applicable  only  from  March  4,  1898,  to  December  31, 


1898. 


Gage 
height. 

Discharge. 

Gage 
height. 

Discharge. 

h?iX        l^^^^arge. 

Gage 
height. 

Discharge. 

Feet. 

Second-ft. 

Feet. 

Second  ft. 

Feet.           Second-ft. 

Feet. 

Second-ft. 

8.0 

26 

5.6 

130 

8.2 

850 

10.8 

610 

8.1 

28 

5.7 

137 

8.3  • 

360 

10.9 

620 

8.2 

80 

5.8 

144 

8.4 

370 

11.0 

630 

8.8 

82 

5.9 

151 

8.5 

380 

11,1 

640 

8.4 

84 

6.0 

159 

8.6 

890 

11.2 

650 

8.5 

86 

6.1 

167 

8.7 

400 

11.3 

660 

8.6 

88 

6.2 

175 

8.8 

410 

11.4 

670 

8.7 

41 

6.3 

188 

8.9 

420 

11.5 

680 

3.8 

44 

6.4 

191 

9.0 

430 

11.6 

690 

8.9 

47 

6.5 

199 

9.1 

440 

11.7 

700 

4.0 

50 

6.6 

207 

9.2 

450 

11.8 

710 

4.1 

58 

6.7 

215 

9.3 

460 

11.9 

720 

4.2 

56 

6.8 

224 

9.4 

470 

12.0. 

780 

4.8 

59 

6.9 

233 

9.5 

480 

12.1 

740 

4.4 

62 

7.0 

242 

9.6 

490 

12.2 

750 

4.5 

66 

7.1 

251 

9.7 

500 

12.3 

760 

4.6 

70 

7.2 

260 

9.8 

510 

12.4 

770 

4.7 

75 

7.3 

269 

9.9 

520 

12.5 

780 

4.8 

80 

7.4 

278 

10.0 

530 

12.6 

790 

4.9 

85 

7.5 

287 

10.1 

540 

12.7 

800 

5.0 

91 

7.6 

296 

10.2 

550 

12.8 

810 

5.1 

97 

7.7 

305 

10.3 

560 

12.9 

820 

5.2 

108 

7.8 

314 

10.4 

570 

13.0 

830 

5.8 

109 

7.9 

323 

10.5 

580 

13.1 

840 

5.4 

116 

8.0 

332 

10.6 

590 

13.2 

8.50 

5.5 

123 

8.1 

841 

10.7 

600 

13.3 

860 

ESTIMATED  MONTHLY  DISCHARGE 

OP  RIO  DESEADO 

AT  CAMP  NO.  7. 

Month. 

Discharge  in  Second-feet 

r                                                                                                                                              ^ 

Maximum.   Minimum.   Mean. 

Total  for 
Month  in 
Acre-feet. 

Month. 

Discharge  in  Second-feet. 
Maximum.    Minimum.    Mean. 

Total  for 
Month  in 
Acre-feet. 

1898. 
March 

185 

462 

68 
34 

107 
111 

6,579 
6,605 

1898. 
Autrust  .... 

482 
243 

Brought  tory 
70             200 

27                78 

vard,  48,388 
12,300 

April 

September  . 

4,640 

May 

223 

81 

97 

5,964 

October  .... 

278 

42 

99 

6,090 

June 

267 

80 

137 

8,150 

November   . 

854 

322 

19,160 

July 

794 

122 

348 

21,090 

48,388 

December  . . 
Total  . . 

324 

90 

221 

13,. 590 
104,168 

MISCELLANEOUS  DISCHARGE  MEASUREMENTS  IN  NICARAGUA. 

Made  by  A.  P.  Davis,  1898. 


Date. 


Stream. 


Locality. 


Meter      Gage  height  Area  of  sec.    Mean  veloc.    Discharge 
number.  (feet).  (sq.ft.;.      (ft.  per  sec.).    (sec-ftT). 


Jan.  18 Las  Lajas. 

**      18 Guiscoyol 

««     80 Jicoral  ... 

May   12 Machuca.. 

July    9 Machuca. 

June  21 OUate 


At  mouth 

94 

2  miles  up. . . . 

94 

Jicoral  

94 

}4  nille  up 

94 

2  miles  up 

94 

8     **       «'  

94 

7.88 


2.60 


2.8 

1.46 

4.1 

6.1 

0  32 

2.0 

20.0 

0  47 

9.4 

68.0 

1.  10 

75.0 

156.0 

1.70 

266.0 

1079.0 

3.94 

4258.0 

260 


NICARAGUA  CANAL  COMMISSION 


RECORD  OP  RIVER  GAGINGS  FOR  VELOCITY  AND  VOLUME. 
Taken  from  Appendix  C  of  Report  of  Nicaragua  Canal  Board,  1895. 


River. 


Locality. 


ii 


ti 


(t 


it 


(( 


Colorado 
River 

Lower 
San  Juan 

San  Juan 

San  Juan 

(i 

({ 

ii 
(i 

i< 

ii 

Colorado 

Lower 
San  Juan 

San  Juan 


Date. 


San  Juan  Fort  San  Carlos  June  5,  1850 


Authority. 


Immediately  above 

mouth  of 
San  Carlos  River 

Immediately  below 

mouth  of 

San  Carlos  River 

Immediately  above 

;nouth  of 

Sarapiqui  River 

Immediately  below 

mouth  of 

Sarapiqui  River 

Immediately  above 

head  of 

Colorado  River 


I 


Above  Toro  Rapids 

Below  mouth  of 
Poco  Sound 

Above  mouth  of 
Santa  Cruz 

Below  mouth  of 
Santa  Cruz 

Above  Mico  Rapids 

Above  mouth  of 
San  Carlos 

Above  mouth  of 
Sarapiqui 

Below  mouth  of 
Sarapiqui 


O.  W.  Chllds 


Between  mouth  of 
Sad  Carlos  and  Ochoa 


July  15, 1850 

July  15,  1850 

Aug.  8,  1850 

Aug.  8,  1850 

Aug.  30,1850 

Aug.  30, 1850 

Aug.  30,  1850 

April  36,  1878 
April  80,  1873 

May  1,  1873 

May  3,  1873 

May  6,  1878 
May  10,  1873 

May  16,  1873 

May  16,  1873 

May  19,  1873 
May  30,  1873 


May  31  to  36, 

1888 


<i 


ii 


it 


ti 


ti 


ti 


tt 


Lull 


it 


it 


tt 


tt 


ii 


it 


it 


it 


It 


Area  of 

cross  see. 

(sq.  ft). 


Canal  Co.,  by 
J.  H.  Covode 


11,810 


Velocity 
per  sec. 

(ft.). 


Discharge 
per  sec. 
(cu.  ft.). 


Remarks. 


11,930  Lake  Nicaragua  at  an 
elevation  103.07,  low 
stage. 


3.665 


19,300 

36,747 

39,536 

53,793 

54,880 

43,056 

13,334 

13,096 
11,390 

11,630 

13,453 

13,943 
13,306 

14,573 

16,770 

16,190 
607 

41,451 


Medium  stage. 


it  «« 


it 


ii 


«t  u 


CC  ii 


ii  ti 


ti  it 


Ele.  of  Lake  Nicaragua 
Sept.  19,  1850,  105.63. 

Ele.  of  Lake  Nicaragua, 
103.38,  low  stage. 


it 


it 


tt 


it 


tt 


it 


it 


tt 


tt 


it 


it 


it 


ct 


«c 


«l 


tt 


tt 


it 


Medium  stage. 


APPENDIX   III.— HTDROQRAPHIC   REPORT  261 

RECORD  OP  RIVER  OAOING8  FOR  VELOCITY  AND  VOLUME.— Con Unued. 


Rivet. 

locality. 

Date. 

Authoiltf. 

Ai«aor 

Velocitr 

DiKjharsc 

8>i>  Joan 

Fort  Ban  Carlos 

May  27,  1895 

Nic.  Canal 
Board 

7,480 

9,430 

Lakeatelev.  101.07  ft., 
velocltiea  meaa'd  with 
floatBimmeraea5';low 

8mn  Carloa 

Below  mouth  of 
aartplqol 

Immedlatoly  abOTe 
moDtb 

June  30,  1895 

Jnly  IS,  1850 

Nov.  SO,  1888 
Ang.  8,  1850 

0.  W.  ChildB 

Canal  Co.  by 
J.  F.  LeBaroQ 
0.  W.  CblldB 

91,500 



3.60 

60,300 

16,447 

7,844 
18,268 

Bta^e,   coefflclent,  0.0. 
UbIdu'   surface   velocity 
low  atage,  coefflclent. 

a8. 

Medium  stage. 

month 

„      „ 

Duit& 

SOiy  above  month 

Mar.  31,188M 
Jnlj  Ifl,  1B88 

Canal  Co.  by 
J.  F.  Le  Baron 

87.5 
611 

0.40 
1.26 

85 

7S4 

Low  Btage. 
High  stage. 

San 
FnnclKo 

Below  month  of 

Chancboi 

Mar.  aa,  1888 

390 

0.60 

174 

Using  surface  velocity, 
low  stage. 

•• 

Camp  Ban  Franc lico 

200/  below  Camp 
San  Franclaco 

Junel4, 1895 
Janeli,  18HS 

NIC.  Canal 
Board 

231 

BOB 

1.70 

i.ai 

370 
818 

„ 

Below  month  ot 
Cbancho* 

Jnnel6,ie95 

515 

l.SO    . 

669 

" 

NlcholsoQ 

Embankment  C  to  Ming 

Jane  14, 1865 

100 

1.70 

170 

.. 

ChKDchoi 

" 

Jane  16, 1895 

200 

1.60 

8B4 

.. 

Llmplo 

J  a  at  below  Camp 
Carmen 

Jnne  16, 1896 

45 

1.30 

68 

,. 

At  Camp  Carmen 

June  16,1806 

S4 

1.90 

86 

., 

Joat  above  Junction 
with  the  Lindo 

June  16, 1896 

e 

1.80 

16 

" 

Llndo 

Jnst  above  junction 
with  Limplo 

Jnne  16. 1895 

10.4 

1,60 

17 

„ 

Deiesdo 

Sew  tlte  of  Virginia 

Dam 

June  17,  1896 

50 

3.00 

150 

" 

laoc  below  Camp 
Menocal 

Jnne  18, 189B 

377 

2,30 

637 

" 

'■ 

Near  Camp  No.  7 

Jnne  18, 1895 

■' 

484 

1,5 

737 

" 

Near  Lock  No.  1 

Dec.  14, 1892 

Canal  Co.,  by 
Boyd  Ebl« 

386 

Water  anrface  alevatlno 
13.38,  medlnm  atage. 

262 


NICARAGUA  CANAL  COMMISSION 


Raixfall. 

Observations  of  rainfall  were  made  at  each 
river  station,  the  form  of  gage  used  at  most  of 
the  stations  being  a  metal  funnel  which  caught 
the  rain  and  discharged  it  into  a  bottle,  from 
which  it  was  measured  in  a  graduate  bearing  a 
known  relation  to  the  diameter  of  the  funnel. 
The  gage  was  always  placed  in  a  position  as 
exposed  as  possible,  but  nearly  always  this  was 
a  small  clearing  in  the  forest,  which  was  still 
well  sheltered  from  the  wind. 

One  of  the  most  remarkable  characteristics  of 
Nicaragua  is  its  rainfall,  and  the  radical  and 
striking  diiferences  in  the  climate  of  the  east 
and  west  coasts  with  reference  thereto. 

The  diagram  (Plate  XI),  shows  graphically 
the*  contrast  in  the  distribution  of  rainfall  at 
Brito  near  the  Pacific  coast  and  on  the  Rio  De- 
seado,  a  short  distance  inland  from  Greytown. 
From  this  it  will  be  seen  that  there  is  no  definite 
dry  season  on  the  eastern  coast,  but  that  rain 
may  be  expected  any  day  in  the  year,  and  the 
expectation  will  seldom  be  disappointed. 

At  Brito,  on  the  contrary,  there  is  no  rain 
from  the  beginning  of  the  record  in  January  till 
the  middle  of  May,  when  the  rainv  season  be- 
gins,  but  the  region  is  subject  to  violent  down- 
pours during  the  rainy  season,  the  precipitation 
for  a  single  day  observed  at  this  station  on  the 
22d  day  of  May  being  5.6  inches. 

No  less  remarkable  is  the  excessive  aggregate 
of  rainfall  in  a  limited  district  of  which  the 
nucleus  seems  to  be  in  the  vicinity  of  Greytown. 
The  annual  rainfall  at  this  point,  as  deduced 
from  the  mean  of  four  years'  observation,  is 
about  250  inches,  while  that  at  Bluefields  is 
only  about  90,  at  Port  Limon  somewhat  less, 
and  at  San  Jose  de  Costa  Rica  about  68.  While 
there  is  a  slight  increase  of  rainfall  with  altitude 


on  the  headwaters  of  the  Deseado  and  Limpio, 
yet  in  general  it  may  be  said  that  the  rainfall 
decreases  as  we  pass  up  the  San  Juan,  as  shown 
by  the  diagram,  Plate  Xin.  No  definite  limits 
can  be  assigned  to  this  district  of  excessive  rain- 
fall, nor  is  it  known  in  what  ratio  the  precipita- 
tion decreases  to  the  northward  and  southward. 
So  far  as  known,  no  satisfactory  theory  has  yet 
been  advanced  to  account  for  this  local  phe- 
nomenon. 

Mr.  William  Climie  reports  a  rainfall  of  nine 
inches  in  nine  hours  at  Nandaime,  a  small  town 
south  of  Granada^  No  such  precipitation  has 
been  observed  by  this  party,  however,  the  heavi- 
est rainfalls  in  1898  being  as  follows: 

Inches 
station.  Date.  Time.         of  Rain. 

Morrito,  Sept.  14,  10  hrs.  4.65 

Ft.  San  Carlos,        Jime  18,  J  hr.  1.83 

Sabalos,  June  18,  IJ  hr.  2.32 

Sabalos,  Oct  27,  2  hrs.  3.11 

Rio  San  Carlos,        June  21,  1  hr.  1.55 

Rio  San  Francisco,  Nov.  7,  night,  3.70 

The  heaviest  general  rain  storm  of  the  season 
began  in  the  night  following  November  15, 
1898,  and  passed  westward,  a  heavy  precipita- 
tion being  shown  at  all  stations  east  of  Lake 
Nicaragua.  The  observed  quantities  are  as 
follows: 

Grevtown   4.85  inches  fell  in  24  hours. 


i( 


7.92 

Rio  Deseado 6.26 

Rio  San  Francisco.  .6.51 

Ochoa   3.60 

Sarapiqui    3.45 

Fort  San  Carlos  . . .  1.05 


u 
ii 
(( 
u 
i( 

(6 


i6 


48 
24 
24 
one  night. 


i6 


(6 


6i 


i6 


ii 


dav. 


The  following  records  of  heavy  rainfalls  were 
compiled  by  the  Canal  Board  of  1895  and  are 
published  in  Appendix  E  of  their  report. 


NICARAGUA  CANAL  COMMISSION 


JANUARY 


FEBRUARY 


MARCH 


APRIL 


MAY 


I 


r 


1 


o 


f     ja     MS     M    »       i 

8       W     t*     90    »S 

B       Mf      tS     H>      gS 

t      Mf      U     »0     »S 

«      M     Jf     J0     JSS 

/? 

/i 

y 

I 

^  i 

"> 

s 

o 

A/ 

1 

J 

L 

■ 

"^ 

■ 

.1. 

I 

1 

i 

1 

JE 

I 

7      A. 

i 

S      30     7, 

11 

1 

1      JO      tl 

h 

1  » 

I 

9     Z 

i 

*     Ji 

Jl 

If    2S        I 

i 

s     * 

L 

9     Ji 

(   s 

tf     2, 

5     1      s     i 

>       i! 

1 

(    to 

Jit 

JANUARY 


FEBRUARY 


MARCH 


APRIL 


MAY 


COMPARISON  OF  DAILY   RAINFALL  ON   RIO 


APPENDIX  3,  PLATE  XI 

COST  SEPTEMBER  OCTOBEB  NOVEMBER  DECEMBER 


JULY  AUGUST  SePTCIDBEn  OCTOBER  NOVEMBER  DECEMBER 

TERN  COAST,  AND  BRITO,  NEAR  WESTERN  COAST,  1896. 


APPENDIX   III.— HYDROGRAPHIC   REPORT 


263 


LARGE  MONTHLY  RAINFALLS  AT  GREYTOWN. 


Month.  Inches. 

November,  1889  (in  24  days) 50.70 

December,   1889 64.39 

June,  1890 41.56 

July,  1890 52.59 

August,   1890 36.61 


Month.  Inches. 

December,  1890 4  L65 

December,  1891 32.74 

May,  1892 * 50.88 

July,  1892 88.96 

November,  1892 36.98 


LARGE  DAILY  RAINFALLS  AT  GREYTOWN. 


Date.  Inches. 

July  1,  1890 4.20 

July  2,  1890 4.31 

July  11,  1890 4.18 

July  12,  1890 2.19 

July  13,  1890 5.03 

July  14,  1800 4.66 

July  15,  18JK) 2.57 

September  7,  1890 4.05 

October  9,  1890 4.00 

November  5,  1890 4.10 

December  27,  1890 7.65 

January  20,  1891 4.35 

April  28,  1891 5.75 

June  5,  1891 3.88 

June  6,  1891 4.95 

Total  for  2  days 8.78 

June  22,  1891  (9  hours) 4.51 

July  18,  1891  (9  hours) 8.17 

December  8,  1891 4.05 


Date.  Inches. 

May  1,  1892 5.08 

May  2,  1892 4.95 

May  3,  1893 4.57 

May  4,  1892 1.63 

Mays,  1893 6.10 

May  6,  1893 5.80 

May  7,  1893 4.10 

May  8,  1892 4.20 

Total  for  8  days 35.42 

July  23,  1892 5.30 

October  29,  1892 5.78 

October  80,  1892 3.50 

October  31,  1893 8.03 

Total  for  8  days 17.30 

November  20,  1892 5.13 

December  5,  1892 8.95 

June  3,  1893 4.00 

June  19,  1893 r 5.00 


LARGE  DAILY  RAINFALLS  AT  CAMP  No.  4. 


Date.  Inches. 

July  -,  1890 5.25 

July  5,  1891 7.70 


Date. 
July  6,  1891 


Inches. 
. .   6.70 


LARGE  DAILY  RAINFALLS  AT  CAMP  CARAZO. 


Date.  Inches. 

June  37,  1888 4.60 

December  4,  1888 4.00 

May  21,  1889 2.90 

October  20,  1889 '. 3.00 


Date.  Inches. 

December  19, 1889 2.90 

December  28,  1889 3.50 

January  23,  1890 3.00 


LARGE  DAILY  RAINFALL  AT  SILICO  LAKE. 


Date. 
April  -,  1890 


Inches. 
. .    7.13 


264  NICARAGUA   CANAL  COMMISSION 


DAILY  RAINFALL  AT  BRITO  AND  TOLA  FOR  1898. 


Day. 

Jan. 

Feb. 

Mar. 

Apr. 

May. 

June. 

July. 

Aug. 

Sept. 

Oct. 

• 

Nov. 

Dec 

1 

0.00 

0.00 

0.00 

0.00 

0.00 

0.00 

.54 

0.00 

0.00 

2.50 

0.00 

0.02 

2 

0.00 

0.00 

0.00' 

0.00 

0.00 

0.00 

.82 

.06 

0.00 

.06 

0.00 

0.00 

3 

0.00 

0.00 

0.00 

0.00 

0.00 

0.00 

.65 

.00 

0.00 

1.25 

0.00 

0.00 

4 

0.00 

0.00 

0.00 

0.00 

0.00 

0.00 

0.00 

.13 

.01 

0.00 

.09 

0.00 

5 

0.00 
0.00 

0  00 
0.00 

0.00 
0.00 

.08 
0.00 

0.00 
0.00 

0.00 
0.00 

0.00 
0.00 

0.00 
.35 

.22 
.02 

.57 

.01 

0.00 
0.00 

0  00 

6 

0.00 

7   

0.00 

0.00 

0.00 

0.00 

0.00 

2.75 

.98 

.02 

.10 

2.13 

0.02 

0.00 

8 

0.00 

0.00 

0.00 

0.00 

0.00 

.07 

.01 

.23 

.45 

.14 

1.08 

0.00 

9 

0.00 

0.00 

0.00 

0.00 

0.00 

0.00 

.26 

0.01 

.02 

1.45 

.99 

.25 

10 

0.00 

0.00 

0.00 

0.00 

0.00 

.14 

.84 

.03 

1.53 

1.47 

.08 

.02 

11 

0.00 

0.00 

0.00 

0.00 

0.00 

.08 

.36 

.16 

.03 

1.59 

.12 

0.00 

12 

0.00 

0.00 

0.00 

0.00 

0.00 

.06 

.01 

0.00 

.21 

0.00 

1.24 

0.00 

13 

0.00 

0.00 

0.00 

0.00 

0.00 

.08 

.07 

.29 

.80 

.14 

1.20 

0.00 

14 

0.00 

0.00 

0.00 

0.00 

0.00 

0.00 

.03 

.31 

1.50 

1.58 

.02 

0.00 

15 

0.00 

0.00 

0.00 

0.00 

0.00 

0.00 

.01 

.01 

.34 

1.96 

.19 

0.00 

16 

0.00 

0.00 

0.00 

0.00 

0.00 

0.00 

.54 

.04 

.42 

.48 

.39 

.03 

17 

0.04 

0.00 

0.00 

0.00 

0.00 

.30 

.88 

.12 

0.00 

•17 

.05 

.03 

18 

0.00 

0.00 

0.00 

0.00 

.04 

.04 

1.04 

.01 

0.00 

1.25 

.04 

.02 

19 

0.00 

0.00 

0.00 

0.00 

.02 

.55 

.09 

.01 

.02 

2.45 

.04 

0.00 

20 

0.00 

0.00 

0.00 

0.00 

.28 

0.00 

.02 

.02 

.47 

.50 

.09 

0.00 

21 

0.00 

0.00 

0.00 

0.00 

.20 

.58 

.13 

1.76 

3.54 

2.19 

0.00 

0.00 

22 

0.00 

0.00 

0.00 

0.00 

5.58 

.50 

.15 

.10 

1.00 

2.96 

.11 

0.00 

23 

0.00 

0.00 

0.00 

0.00 

2.04 

.01 

0.00 

.23 

.17 

.02 

0.00 

0.00 

24 

.15 

0.00 

.08 

0.00 

1.73 

1.40 

.58 

.08 

.79 

.05 

0.00 

0.00 

25 

0.00 

0.00 

0.00 

0.00 

.56 

.06 

.04 

.53 

.10 

.30 

.02 

0.00 

26 

.06 

0.00 

0.00 

0.00 

.41 

2.31 

.13 

.09 

1.43 

.15 

.02 

0.00 

27 

0.00 

0.00 

0.00 

0.00 

0.10 

1.76 

.15 

.61 

3.18 

.05 

.15 

.12 

28 

0.00 

0.00 

0.00 

0.00 

0.00 

4.18 

.09 

.31 

.25 

.23 

.02 

1.19 

29 

0.00 

0.00 

0.00 

0.00 

.01 

.04 

0.00 

.59 

0.00 

0.00 

.05 

.58 

oi) .  ...    ... 

0.00 

0.00 

0.00 

0.00 

.33 

0.00 

3.49 

.05 

0.00 

.05 

0.00 

.10 

31 

0.00 

0.00 

0.00 

•   •  •  • 

0.00 

•  •  •  • 

.01 

.02 

•    •   •   • 

0.00 

•   •   •   • 

.05 

Totals.. 

.25 

0.00 

.08 

.08 

11.30 

14.86 

11.42 

6.17 

16.60 

25.70 

6.01 

2.41 

DAILY  RAINFALL  AT  RIVAS  FOR  1898. 


Day.  Jan.  Feb.  Mar.  Apr.  May.        June.        July.         Augr.         Sept.         Oct.  Nov.  Dec. 

1 

2 

8 

4 

6   

6 

7 

8 

9 

10 


0.00 

0.00 

0.00 

0.00 

0.00 

0.00 

0.00 

0.00 

0.00 

0.09 

0.00 

0.07 

0.00 

0.00 

0.00 

0.00 

0.00 

0.00 

1.42 

0.00 

0.44 

0.34 

0.00 

0.00 

0.00 

0.00 

0.00 

0.00 

0.00 

0.00 

0.40 

1.00 

0.40 

1.60 

0.00 

0.00 

0.00 

0.00 

0.00 

0.00 

0.00 

0.00 

0.00 

0.00 

0.00 

0.55 

0.06 

0.00 

0.00 

0.00 

0.00 

0.00 

0.00 

0.00 

0.00 

0.53 

0.00 

0.09 

0.00 

0.00 

0.00 

0.00 

0.00 

0.00 

0.16 

0.00 

0.00 

0.00 

0.14 

0.23 

0.00 

0.00 

0.00 

0.00 

0.04 

0.00 

0.00 

0.04 

1.97 

0.80 

0.21 

0.08 

0.10 

0.00 

0.00 

0.00 

0.00 

0.00 

0.00 

0.13 

0.00 

0.00 

0.06 

1.91 

2.76 

0.00 

0.00 

0.00 

0.00 

0.00 

0.00 

0.15 

0.78 

0.00 

1.38 

0.80 

0.04 

0.20 

0.00 

0.00 

0.00 

0.00 

0.00 

0.40 

0.40 

0.00 

0.00 

0.63 

0.04 

0.00 

APPENDIX   III.— HYDROGRAPHIC   REPORT 


265 


DAILY  RAINFALL  AT  RIVAS  FOR  1898.— Continued. 


Day. 

Jan. 

Feb. 

Mar. 

Apr. 

May. 

June. 

July. 

Aug, 

Sept. 

Oct 

Nov. 

Dec. 

11 

0.12 

0.00 

0.00 

0.00 

0.11 

0.00 

0.00 

0.20 

0.80 

0.43 

1.23 

0.00 

12 

0.00 

0.00 

0.00 

0.00 

0.00 

0.00 

0.00 

0.00 

0.20 

0.00 

1.77 

0.00 

18 

0.00 

0.00 

0.00 

0.00 

0.00 

0.16 

0.00 

1.71 

0.00 

0.00 

0.69 

0.00 

14 

0.00 

0.00 

0.00 

0.00 

0.00 

0.00 

0.00 

0.80 

1.26 

1.57 

0.00 

0.00 

15 

0.00 

0.00 

0.00 

0.00 

0.60 

0.08 

0.00 

0.08 

1.77 

1.65 

0.37 

0.00 

16 

0.00 

0.00 

0.00 

JO.  00 

0.00 

0.00 

0.00 

0.00 

0.86 

2.56 

0.38 

0.08 

17 

0.15 

0.00 

0.00 

0.00 

0.00 

1.16 

1.18 

0.00 

0.59 

0.00 

0.00 

0.06 

18 

0.00 

0.00 

0.00 

0.00 

0.20 

3.98 

0.86 

0.00 

0.00 

0.30 

0.00 

0.00 

19 

0.00 

0.12 

0.00 

0.00 

3.15 

1.26 

0.18 

0.00 

0.37 

0.89 

0.13 

0.00 

20 

0.00 

0.00 

0.00 

0.00 

1.30 

1.67 

0.00 

0.00 

2.16 

1.22 

0.00 

0.00 

21 

0.00 

0.00 

0.00 

0.00 

0.00 

0.00 

0.80 

3.15 

0.87 

1.75 

0.00 

0.00 

22 

0.00 

0.00 

0.00 

0.00 

5.33 

3.22 

0.00 

0.40 

0.43 

1.78 

0.00 

0.00 

28 

0.00 

0.00 

0.00 

0.00 

4.57 

0.40 

0.40 

0.60 

0.30 

0.00 

0.00 

0.00 

24 

0.18 

0.00 

0.00 

0.00 

0.79 

0.40 

0.00 

0.04 

0.00 

0.12 

0.00 

0.00 

25 

0.00 

0.00 

0.06 

T. 

0.90 

0.30 

0.20 

0.37 

0.00 

0.47 

0.00 

0.00 

26 

0.62 

0.00    . 

0.00 

0.00 

0.20 

0.00 

0.00 

0.00 

1.26 

0.00 

0.00 

0.00 

27 

0.00 

0.00 

0.00 

0.00 

1.07 

4.72 

0.40 

0.00 

0.90 

0.00 

0.36 

0.23 

28 

0.00 

0.00 

0.00 

0.00 

0  00 

1.18 

0.00 

0.40 

0.09 

0.98 

0.31 

2.15 

29 

0.00 

0.00 

0.00 

0.00 

0.79 

0.00 

0.00 

1.77 

0.00 

0.00 

0.00 

0.00 

80 

0.00 

0.00 

0.00 

0.00 

0.00 

0.00 

3.86 

0.00 

0.00 

0.79 

0.00 

0.10 

81 

0.00 

•    •   •    • 

0.00 

•    •    •    • 

0.00 

•   •   •  • 

0.00 

0.00 

•   •  •  • 

0.00 

•   •   •   • 

0.25 

Totals.. 

1.07 

0.12 

0.10 

0.00 

16.17 

18.95 

13.65 

11.85 

13.99 

20.83 

8.19 

3.14 

DAILY  RAINFALL  AT  THE  MOUTH  OF  RIO  LAS  LAJAS  AT  CAMP  CALDERA  NEAR  RIVAS, 

NICARAGUA. 


Day.      Jan.       Feb. 
1898. 

3far. 

Apr. 

May. 

June. 

July. 

Aug, 

Sept 

Oct 

Nov. 

*.^CC« 

JanI 

■loWf. 

Feb. 

Mar. 

1 

.00 

.00 

.00 

.00 

.00 

0.33 

.00 

0.01 

0.15 

.00 

0.03 

.01 

.00 

.00 

2 

.00 

0.04 

.00 

.00 

.00 

1.23 

.00 

.00 

.05 

.00 

0.09 

.00 

.00 

.00 

8 

.00 

.00 

.00 

.00 

.00 

0.24 

.00 

.00 

1.17 

.00 

.00 

.10 

.00 

.00 

4 

.00 

.00 

.00 

.00 

.00 

.00 

0.37 

0.27 

.01 

0.17 

.00 

.02 

.00 

.00 

5 

.00 

.00 

0.12 

.00 

0.33 

.00 

.00 

.00 

.43 

.00 

.00 

.03 

.00 

.00 

6 

.00 

.00 

0.02 

0.08 

.00 

.00 

1.40 

0.08 

.00 

.00 

.00 

.00 

.00 

.00 

7 

.00 

0.01 

.00 

.00 

0.74 

0.26 

0.11 

^.01 

.96 

0.12 

.00 

.00 

.00 

.03 

8 

.00 

.00 

.00 

.00 

0.09 

.00 

0.21 

0.04 

.93 

0.07 

.00 

.00 

.00 

.00 

9 

0.05 

.00 

.00 

.00 

0.08 

0.16 

.00 

0.05 

1.07 

1.20 

0.18 

.00 

.06 

.00 

10 

.00 

.00 

.00 

.00 

0.40 

0.85 

.00 

0.46 

.58 

0.06 

.00 

.00 

.00 

.00 

11 

.00 

.00 

.00 

0.06 

0.02 

0.83 

.00 

0.03 

.12 

0.01 

.00 

.13 

.00 

.00 

12 

.00 

.00 

0.05 

.00 

0.05 

.00 

0.05 

0.02 

.00 

0.90 

.00 

.03 

.00 

.00 

18 

.00 

.00 

.00 

.00 

0.01 

0.07 

0.04 

1.06 

.29 

1.07 

0.01 

.05 

.00 

.00 

14 

.00 

.00 

.00 

.00 

.00 

0.02 

0.41 

0.62 

1.01 

.00 

.00 

.00 

.00 

.00 

15 

.00 

0.08 

.00 

0.03 

.00 

0.03 

.00 

0.10 

1.74 

.00 

.00 

.15 

.00 

.00 

16 

.00 

0.04 

.00 

0.16 

.00 

0.30 

0.01 

.00 

2.49 

0.15 

0.01 

.00 

.00 

.00 

17 

.00 

.00 

.00 

.00 

0.84 

0.67 

0.13 

.00 

.04 

0.05 

.00 

.00 

.30 

.00 

18 

.00 

.00 

.00 

0.03 

0.22 

0.62 

0.08 

.00 

.64 

.00 

0.01 

.00 

.00 

.00 

19 

.00 

.00 

.00 

0.58 

0.43 

0.26 

.00 

0.09 

.20 

0.06 

00 

.00 

.25 

.00 

20 

.00 

.00 

.00 

0.66 

0.51 

0.06 

0.01 

0.04 

.59 

0.10 

.00 

.00 

.05 

.00 

266 


NICARAGUA  CANAL  COMMISSION 


Day. 


DAILY  RAINFALL  AT  THE  MOUTH  OP  RIO  LAS  LAJAS  AT  CAMP  CALDERA  NEAR  RIVAS. 

NICARAGUA  .—Continued. 


Jan. 


Feb. 


Mar. 


Apr.       May.       June.      July.        Aug.      Sept. 


Oct. 


Nov.       Dec. 


Jan. 
1899. 


Feb. 


Mar. 


21 

.00 

.00 

0.05 

0.03 

1.40 

0.33 

3.61 

2.47 

1.03 

.00 

.00 

.00 

.00 

.00 

22       . 

.00 

.00 

.00 

3.99 

2.04 

0.21 

0.07 

0.04 

.18 

.00 

0.13 

.00 

.00 

.00 

23 

.00 

0.02 

.00 

1.44 

0.06 

0.40 

0.01 

0.03 

.02 

^                                     •N 

.00 

.01 

.00 

.00 

24       . 

.00 

1.11 

.00 

1.89 

0.85 

0.29 

.00 

0.10 

.00 

.00 

.00 

.00 

.00 

25 

.00 

.00 

.00 

0.19 

0.03 

0.06 

0.15 

0.03 

1.08     ^ 

0.20 

►    .00 

.00 

.00 

.00 

26       0 

.06 

00 

.01 

0.03 

0.67 

0.97 

0.18 

0.10 

0.19 

0.00 

.00 

.00 

.00 

.00 

27 

.00 

.00 

.00 

.00 

0.06 

3.22 

0.07 

0.48 

0.19 

0.11 

0.06 

0.10 

.00 

.00 

.00 

28 

.00 

.00 

.00 

0.01 

.00 

1.09 

0.54 

.00 

0.86 

1.34 

0.18 

1.82 

.00 

.01 

.00 

29 

.00 

«    • 

.00 

.00 

0.02 

0.10 

.00 

1.07 

.00 

0.01 

.00 

0.12 

.00 

.00 

30       . 

•      •       •                                  Si 

•    • 

.00 

.00 

0.70 

0.02 

3.18 

0.13 

.00 

0.00 

0.01 

0.04 

.00 

»  •  • 

.00 

31 

.00 

•    • 

0.08 

•   •   •   • 

0.02 

. .  ■  • 

.00 

0.05 

•   •   •  • 

0.00 

«   •   •   • 

0.22 

.00 

»  •   • 

.30 

Totals 

.06 

.05 

1.34 

.28 

10.60 

13.50 

10.64 

8.44. 

6.79 

16.19 

4.41 

3.26 

0.53        0.67 

.83 

DAILY  RAINFALL  AT  PASO  REAL  DEL  RIO  VIEJO. 


Day.         Feb.  Mar. 
1886. 

1 joio  !oo" 

2 00  .00 

3 00  .42 

4 00  .22 

5 00  .00 

6 00  .00 

7 00  .00 

8 00  .00 

9 00  .00 

10 00  .00 

11 00  .00 

12 00  .00 

13 T.  .00 

14 00  .00 

15 00  .00 

16 00  .00 

17 00  .00 

18 00  .00 

19 00  .00 

20 00  .01 

21 00  .00 

22 T.  .01 

23 01  .00 

24 00  .00 

25 00  .00 

26 00  .00 

27 00  .00 

28 00  .00 

29 .00 

30 .00 

31 .00 

Totals..     !oi  .66 


Apr.        May. 


.00 
.00 
.00 
.00 
.00 

T. 
.00 
.00 
.00 
.00 

.00 
.00 
T. 
.00 
.00 

.00 
.00 
.00 
.00 
.00 

.00 
.00 
.00 
.00 
.00 

.00 
.00 
.00 
.00 
.00 

•    •    • 

"iooT 


.00 
.00 
.00 
.00 
.00 

.00 
.00 
.00 
.00 
.00 

.00 
.00 
.00 
.00 
.00 

.00 
.00 
.87 
2.42 
.71 

2.51 
2.83 
1.65 
1.91 
.47 

.05 
.35 
.00 
.00 
.00 
.01 
18.78 


June. 

.00 
.00 
.00 
.00 
.00 

.00 
1.25 
.14 
.00 
.80 

.71 
.05 
.00 
.00 
.00 

.00 
.00 

3.68 
.63 

l.OO 

1.90 
.52 
.19 
.82 

.13 

.00 
.08 
3.56 
.00 
.00 

•   •   • 

18.45 


July.        Aug. 


.00 
.16 
.00 
.00 
.00 

.81 
.18 
.00 
.30 
.70 

.70 
.87 
.00 
.05 
.18 

.00 
.00 
.00 
.00 
.13 

.00 
.00 
.08 
.00 
.00 

.00 
.03 
.62 
.03 
.38 
.03 
4.01 


.88 
.18 
.00 
.06 
.60 

.03 
.00 
.00 
.00 
.00 

.41 

.11 

.81 

1.16 

1.08 

.38 
.50 
.50 
.50 
.50 

.50 
.36 
.00 
.00 
.00 

.08 
.01 
3.78 
.83 
.07 
.00 

11.66 


Sept. 

.00 
.00 
.33 
.00 
.16 

.50 
.01 
.00 
.00 
.40 

.38 
.00 

1.40 
.00 

1.70 

.00 
.00 
.00 
1.85 
.41 

.03 
.07 
.10 
.00 
.00 

.36 
.39 
.01 
.00 
.05 

•   •   • 

7.38 


Oct. 

.00 
1.08 
.31 
.02 
.01 

.48 
.36 

.77 
.03 
.00 

.19 
.37 
.30 
.54 
.03 

.17 

.00 

3.31 

.83 

.87 

.08 
.07 
.03 
.00 
.01 

.39 
.00 
.00 
.16 
.01 
.00 
8.99 


Nov, 

.00 
.00 
.00 
.03 
.00 

.01 
.00 
.06 
.18 
.01 

.03 
.38 
.03 
.00 
.00 

.00 
.00 
.00 
.00 
.00 

.00 
.00 
T. 
.00 
.00 

.00 
.00 
.00 
.00 
.00 

•    •    • 


Dec. 

.00 
.00 
.00 
.16 
.00 

.00 
.00 
.00 
.00 
.00 

.00 
.00 
.00 
.00 
.00 

.00 

.00 

.0 

.00 

.00 

.00 
.01 
.00 
.00 
.00 

.00 
.00 
.00 
.00 
.00 
.00 

.17 


Jan. 
1890. 

.00 
,00 
.08 
00 
.00 

.01 
.00 
.00 
.00 
00 

.00 
00 
.00 
.00 
.00 

.00 
00 
.00 
.00 
.00 

.00 
.00 


0.4 


NICARAGUA  CANAL  COMMISSION 

^ 

g 

IL 

MA 

JUNE 

R  h 

D 

ff 

3 

-A 

SI. 

A' 

\ 

. 

Rl(3 

L 

/f 

' 

3 

-/ 

S 

V 

1 

1 

1, 

,11 

It     M     K     t 

Kl 

« 

» 

yj    Ji 

I      M     l> 

JANUARY  FEBRUARY  MARCH  APRIL 


DIAGRAM  OF  THE  DAILY  RAI 


APPENDIX  3,  PLATE  XII 
UGUST  8EPTCMSER  OCTOBER  NOVCMBER  DECCMeCR 


1. 


I; 


ik 


I 


lU 


ilJ 


m 


^ 


JUL>  AUCUS-T  SEPTEMBER  OCTOBER 

i,T  TIPITAPA  AND  RIO  VIEJO.  1893. 


MBER       '      DECEMBER 


APPENDIX  III.— HYDROGRAPHIC  REPORT 


267 


DAILY  RAINFALL  AT  TIPITAPA. 


Day. 

Feb. 

lovD. 

Mai. 

Apr. 

May. 

June 

July. 

Aug. 

Sept. 

Oct. 

Nov. 

Dec. 

Jan. 
1899. 

1 

.00 

.00 

.00 

.00 

.00 

.80 

.23 

.87 

.00 

.00 

.00 

T. 

2 

.00 
.00 

.00 
.00 

.00 
.00 

.00 
.00 

.00 
.00 

.26 
.00 

.16 
.04 

.37 
.45 

.00 
.10 

.00 
.00 

.12 
T. 

.00 

3 

.00 

4 

.00 
•00 

.00 
.00 

.00 
T. 

.00 
.00 

.81 
.00 

.00 
.00 

.18 
.00 

.05 
1.03 

.30 
.00 

.11 
.00 

.00 
.00 

.25 

5 

.00 

6 

.00 

.00 

.00 

.00 

.00 

.08 

.00 

.25 

.02 

.00 

.00 

.00 

7 

.00 

.00 

.00 

.00 

.73 

.00 

.81 

.56 

.00 

.00 

t. 

T. 

8 

.00 

.00 

.00 

.00 

.90 

.00 

.01 

.21 

1.72 

.00 

.00 

.00 

9 

.00 

.00 

.00 

.00 

T. 

3.30 

.14 

.15 

.68 

.03 

.00 

T. 

10 

.00 
.00 

.00 
.00 

.00 
.00 

.00 
T. 

.26 

.78 

.19 
.20 

.06 
.40 

.48 
.87 

.02 
.52 

.00 
.01 

.00 
.00 

.00 

11 

.00 

12 

.00 
.00 
.00 

.00 
.00 
.00 

.00 
.00 
.00 

.00 
.00 
.00 

.81 
.04 
.00 

.00 
.00 
.00 

.02 
.01 
.32 

.87 

2.21 

.71 

.00 
.34 
.07 

.71 
.00 
.00 

.00 
.00 
.00 

.00 

13 

.00 

14 

.00 

15 

.00 

.00 

.00 

.00 

.00 

.00 

.00 

.02 

.09 

.00 

.00 

.00 

16 

.00 

•00 

.00 

.22 

.00 

.00 

.35 

.14 

.21 

.00 

.00 

.00 

17 

.00 

.00 

.00 

.00 

.00 

.10 

.01 

.00 

.00 

.00 

.00 

.01 

18 

.00 
.00 
.00 

.00' 

.00 

.00 

.00 
.00 
.00 

3.10 

1.22 

.12 

3.19 
.22 
.32 

.14 
.00 
.00 

.00 
.03 
.04 

.00 
.30 
.01 

.60 

.00 

1.40 

.00 

.00 

T. 

.02 
.00 
.00 

.00 

19 

.00 

20 

.00 

21 

.00 
T. 

.00 
.00 

.00 
.00 

.04 
1.08 

2.08 
.96 

.14 

.18 

.21 
T. 

1.86 
.15 

.00 
.04 

.00 
T. 

.00 
.00 

.00 

22 

.00 

as 

.00 

.26 

.00 

.52 

.00 

.00 

.81 

01. 

.00 

.07 

.00 

.00 

24 

.00 

.00 

.00 

.60 

8.17 

.00 

.09 

T. 

/•                         "^ 

.00 

.00 

25 

.00 

.00 

.00 

.52 

.24 

.00 

.00 

.00 

.00 

.00 

26 

.00 

.00 

.00 

.89 

.00 

.00 

.00 

.85 

.00 

.00 

27 

.00 

.00 

.00 

.12 

.86 

.12 

.03 

1.20      ^ 

1.01 

►     .00 

.00 

28 

.00 

.00 

.00 

.00 

2.29 

.02 

2.10 

.13 

.00 

.00 

29 

•                               •    • 

.00 

.00 

.00 

.00 

.07 

.75 

.00 

.00 

.00 

«0 

•                               •    • 

.00 

.00 

.00 

.27 

.54 

.00 

.00 

.00 

.08 

81 

•                                •    • 

.00 

•    • 

.13 

•   • 

.10 

1.58 

•   • 

>                        ^ 

•    • 

.00 

Total 

.00 

.26 

.00 

8.56 

16.88 

6.24 

7.82 

11.25 

7.12 

.93 

.17 

.26 

DAILY  RAINFALL  AT  MORRITO  FOR  1898. 


Day. 

1 

2 

8 

4 

5.... 

6 

7 

8.... 

9 

10. . . . 


April. 


.01 
.08 
.00 
.00 
.00 


May. 

.02 
.00 
.00 
.00 
.06 

.00 
.00 
.00 
.39 
.00 


June. 

.00 
.00 
.02 
1.17 
.22 

.00 
.18 
.00 
.67 
.46 


July. 

.50 
1.82 
.16 
.20 
.15 

.88 
.30 
.06 
.24 
.19 


Aug. 

.00 
11 
.08 
.00 
.12 

.08 
.04 
.00 
.62 
.00 


APPENDIX  III.— HYDROGRAPHIC  REPORT 


267 


DAILY  RAINFALL  AT  TIPITAPA. 


Day. 

Feb. 

1898. 

Mai. 

Apr. 

May. 

June 

July. 

Aug. 

Sept, 

Oct. 

Nov. 

Dec. 

Jan. 
1899. 

1 

.00 

.00 

.00 

.00 

.00 

.80 

.23 

.37 

.00 

.00 

.00 

T. 

o 

.00 
.00 

.00 
.00 

.00 
.00 

.00 
.00 

.00 
.00 

.26 
.00 

.16 
.04 

.37 
.45 

.00 
.10 

.00 
.00 

.13 
T. 

.00 

3 

.00 

4 

.00 
•00 

.00 
.00 

.00 
.00 

.00 
.00 

.00 
T. 

.00 
.00 

.00 
.00 

.00 
.00 

.31 
.00 

.00 
.73 

.00 
.00 

.08 
.00 

.18 
.00 

.00 
.81 

.05 
1.03 

.25 
.56 

.30 
.00 

.02 
.00 

.11 
.00 

.00 
.00 

.00 
.00 

.00 
t. 

.25 

5 

.00 

6 

.00 

7 

T. 

8 

.00 
.00 

.00 
.00 

.00 
.00 

.00 
.00 

.90 
T. 

.00 
3.30 

.01 
.14 

.21 
.15 

1.72 
.68 

.00 
.03 

.00 
.00 

.00 

9 

T. 

10 

.00 

.00 

.00 

.00 

.26 

.19 

.00 

.48 

.02 

.00 

.00 

.00 

11 

.00 

.00 

.00 

T. 

.78 

.20 

.40 

.87 

.52 

.01 

.00 

.00 

12 

.00 

.00 

.00 

.00 

.81 

.00 

.02 

.37 

.00 

.71 

.00 

.00 

13 

.00 

.00 

.00 

.00 

.04 

.00 

.01 

2.21 

.34 

.00 

.00 

.00 

14 

.00 

.00 

.00 

.00 

.00 

.00 

.32 

.71 

.07 

.00 

.00 

.00 

15 

.00 

.00 

.00 

.00 

.00 

.00 

.00 

.02 

.09 

.00 

.00 

.00 

16 

.00 

•00 

.00 

.22 

.00 

.00 

.35 

.14 

.21 

.00 

.00 

.00 

17 

.00 

.00 

.00 

.00 

.00 

.10 

.01 

.00 

.00 

.00 

.00 

.01 

18 

.00 
.00 
.00 

.00' 

.00 

.00 

.00 
.00 
.00 

3.10 

1.22 

.12 

3.19 
.22 
.32 

.14 
.00 
.00 

.00 
.03 
.04 

.00 
.30 
.01 

.60 

.00 

1.40 

.00 

.00 

T. 

.02 
.00 
.00 

.00 

19 

.00 

20 

.00 

21 

.00 
T. 

.00 
.00 

.00 
.00 

.04 
1.08 

2.08 
.96 

.14 

.18 

.21 
T. 

1.36 
.15 

.00 
.04 

.00 
T. 

.00 
.00 

.00 

22 

.00 

23 

.00 

.26 

.00 

.52 

.00 

.00 

.81 

01. 

.00 

.07 

.00 

.00 

24 

.00 
.00 

.00 
.00 

.00 
.00 

.60 
.52 

8.17 
.24 

.00 
.00 

.09 
.00 

T. 
.00 

^            ■v 

.00 
.00 

.00 
.00 

25 

26 

.00 

.00 

.00 

.89 

.00 

.00 

.00 

.35 

.00 

.00 

27 

.00 

.00 

.00 

.12 

.36 

.12 

.03 

1.20      ^ 

1.01 

►    .00 

.00 

28 

.00 

.00 

.00 

.00 

2.29 

.02 

2.10 

.13 

.00 

.00 

29 

•                           •   • 

.00 

.00 

.00 

.00 

.07 

.75 

.00 

.00 

.00 

50 

•                           •   • 

.00 

.00 

.00 

.27 

.54 

.00 

.00 

.00 

.03 

81 

•                                •    • 

.00 

•    • 

.13 

•    • 

.10 

1.53 

«   • 

^ 

■    • 

.00 

Total 

.00 

.26 

.00 

8.56 

16.88 

6.24 

7.83 

11.25 

7.12 

.93 

.17 

.26 

DAILY  RAINFALL  AT  MORRITO  FOR  1898. 


Day. 

1... 

2..., 

3... 

4... 

5... 

6... 
7... 
8... 
9... 
10. . . 


April. 


.01 
.03 
.00 
.00 
.00 


May. 

.02 
.00 
.00 
.00 
.06 

.00 
.00 
.00 
.39 
.00 


June. 

.00 
.00 
.02 
1.17 
.22 

.00 
.18 
.00 
.67 
.46 


July. 

.50 
1.82 
.16 
.20 
.15 

.38 
.80 
.06 
.24 
.19 


Aug. 

.00 
11 
.03 
.00 
.12 

.08 
.04 
.00 
.62 
.00 


268 


NICARAGUA  CANAL  COMMISSION 


DAILY  RAINFALL  AT  MORRITO  FOR  1898.— Continued. 


Day. 

11... 
12... 
18... 
14.... 
15. . . , 

16.... 

17 

18 

19.... 
20. . . . 

21 

22.... 

23 

24 

25... 

26. . . . 
27. . . . 

28 

29. . . . 
30. . . . 
31 ... . 


April. 


May. 


June. 


July. 


Aug. 


.00 
.00 
.00 
.00 
.00 

.00 
.02 
.00 
.00 
.00 

.00 
.00 
.00 
.00 
.00 

.01 
.00 
.00 
.00 
.00 


.08 
.00 
.00 
.00 

.81 

.06 
.00 
.39 
.03 
.05 

.36 
1.58 
1.84 
2.05 

.00 

.00 
.20 
.00 
.46 
.08 
.51 


.98 
.05 
.00 
.17 
.00 

.05 

.00 

L53 

1.58 

.70 

1.38 

1.85 

.02 

.22 

.16 

.53 
.58 
.87 
.12 
.59 


.20 
.00 
.00 
.86 
.11 

.72 
.24 
.20 
8.14 
.21 

.02 
.86 
.60 
.38 
.70 

.35 
.27 
.17 
.00 
1.77 
.04 


.08 
.00 
2.95 
.00 
.05 

1.03 
.00 
.30 
.04 

0.71 

.12 
.00 
.41 
.00 

.58 

1.24 
1.17 
.07 
.37 
.08 
.00 


Totals. 


.07 


8.92 


14.05 


13.84 


10.20 


DAILY  RAINFALL  AT  FORT  SAN  CARLOS. 


Day. 

Mar. 

1808. 

April. 

May. 

June. 

July. 

Aug. 

Sept. 

Oct. 

Nov. 

Dec. 

Jan. 
1889. 

Feb. 

Mar. 

Apr. 

1 

•   • 

.00 

.51 

.01 

.42 

.19 

.07 

.00 

.04 

.90 

.85 

.00 

.06 

.00 

2 

•   • 

.00 

.13 

.00 

.61 

.32 

.79 

.11 

.00 

.22 

.00 

.15 

.00 

.00 

3 

•   • 

.05 

.00 

.02 

1.66 

.18 

.09 

.01 

.00 

.12 

H 

.00 

.06 

.00 

4 

.05 

.02 

.00 

.57 

.00 

.05 

.48 

.65 

.10 

.10 

.00 

.00 

5 

•   • 

.59 

.06 

.02 

.06 

.67 

.18 

.00 

.21 

.04 

.17 

.00 

.00 

.02 

6 

•   • 

.31 

.08 

.00 

.91 

.58 

.07 

.11 

.00 

.31 

.00 

.24 

.12 

.32 

7 

■   • 

.30 

T 

.35 

.07 

.13 

.81 

.00 

.00 

.18 

.03 

.00 

.04 

.04 

8 

.22 

.00 

T 

.00 

.62 

.07 

.41 

1.23 

.69 

.04 

.06 

.00 

.21 

.09 

9 

.00 

.01 

.88 

.26 

1.05 

.97 

.11 

.04 

.27 

.19 

.88 

.00 

.00 

.29 

10 

.01 

.00 

.33 

.44 

.00 

.47 

.08 

.02 

.53 

.17 

.17 

.00 

.00 

.40 

11 

.00 

.44 

1.00 

.00 

.64 

.13 

3.64 

.02 

.67 

.10 

.05 

.00 

.00 

.22 

12 

13 

.00 
.00 

.15 
.00 

.00 
.00 

.01 
1.56 

.65 
.00 

.08 
1.80 

.68 
.22 

.05 
1.57 

ji.25; 

.07 
.08 

.47 

.05 

.54 

.08 

.04 
.00 

.10 
.00 

14 

15 

.00 
.00 

.00 
.00 

.00 
.19 

.18 
.02 

.33 
.12 

.08 
.00 

2.21 
.00 

.10 
.71 

.89 
.85 

.00 
.00 

.58  1 

.00 
.13 

.00 
.10 

.00 
.00 

16 

17 

.00 
.00 

.00 
.25 

.02 
.33 

.02 
.00 

.00 
.32 

.07 
.01 

.12 
.12 

.00 
.60 

1.05 
.91 

.56 
.44 

j    .53  . 

.11 
.59 

.00 
.00 

.00 
.00 

18 

.00 

.00 

3.05 

1.96 

.18 

.00 

.17 

1.07 

.11 

.02 

.26 

.08 

.00 

.00 

19 

.00 

.00 

.26 

1.02 

.57 

.57 

.04 

.18 

.00 

.00 

.05 

.82 

.00 

.00 

20 

.22 

.01 

.87 

1.66 

.97 

.04 

.84 

.11 

.20 

.00 

.00 

.00 

.00 

.00 

APPENDIX  III.— HYDROGRAPHIC   REPORT 


269 


DAILY  RAINFALL  AT  PORT  SAN  CARLOS.— Continued. 


Day. 

Mar. 
1898. 

April. 

May. 

June. 

JAily. 

Vug. 

Sept. 

Oct. 

Nov. 

Dec. 

Jan. 

1899. 

Feb. 

Mar. 

Apr. 

21 

.10 

.03 

.16 

3.35 

.74 

.03 

.08 

.04 

.08 

.05 

.22 

.05 

.00 

.00 

23 

.06 

.03 

.25 

.67 

.39 

.03 

.05 

.04 

.05 

.05 

.08 

.00 

.00 

.00 

23 

.04 

.30 

.34 

.08 

.27 

.67 

.19 

.00 

.00 

.00 

.05 

.05 

.00 

.00 

24 

.21 

.00 

.19 

.14 

.44 

.05 

.00 

.80 

.00 

.00 

.25 

.00 

.00 

.00 

25 

.19 

.00 

.02 

1.36 

.27 

.04 

.00 

.50 

.97 

.00 

.05 

.00 

.00 

.00 

2fi 

.00 

.43 

.00 

.58 

.99 

-.14 

.04 

.73 

.90 

.07 

.10 

.12 

.00 

.00 

27 

.00 

.00 

.00 

.88 

.09 

.35 

.05 

.26 

23 

.03 

.05 

.25 

.00 

.00 

28 

.00 

.00 

.04 

.72 

.29 

.03 

.00 

.15 

.27 

.89 

.00 

.00 

.00 

.00 

29 

.03 

.00 

.33 

.57 

.02 

.06 

.00 

.00 

.04 

.24 

.10 

•   • 

.00 

.00 

30 

.00 

00 

.10 

.23 

.04 

.02 

.00 

.00 

.00 

.31 

.00 

■   • 

.00 

.00 

31 

.13 

•   • 

.06 

•   • 

.06 

.73 

•    • 

•00 

•   • 

.44 

.20 

•   • 

.42 

.00 

Totals. 

1.21 

3.00 

8.22 

15.56 

13.35 

8.00 

10.56 

8.93 

9.86 

5.62 

4.99 

2.79 

1.05. 

1.48 

MEAN  OF  DAILY  RAINFALL  AT  FORT  SAN  CARLOS  (March  8  to  December  31),  MORRITO  (April  6 

to  August  31),  TIPITAPA  (February  1  to  December  31),  RIO  VIEJO  (February  1  to 

December  31),  LAS  LAJAS  (February  1  to  December  31),  1898. 

Day.                   Feb.  Mar.  April.        May.  June.  July.  Aug.  Sept.  Oct.  Nov.  Dec. 

1 ^00  ^00  [OO  Al  M  ^41  ^35  Al  ^04  ^01  ^8 

2 00  .01  .00  .03  .00  .72  .15  .29  .30  .00  .11 

8 00  .14  .01  .00  .01  .41  .05  .19  .38  .00  .03 

4 00  .07  .01  .00  .30  .15  .12  .09  .20  .24  .06 

5 00  .00  .18  .03  .11  .04  .28  .34  .11  .05  .01 

6 00  .00  .07  .08  .00  .34  .42  .22  .14  .00  .08 

7 00  .00  .07  .00  .65  .16  .24  .22  .33  .03  .05 

8 00  .06  .00  .00  .24  .14  .06  .16  1.16  .21  .01 

9 02  .00  ^00  .15  .20  1.01  .85  .08  .45  .41  .09 

10 00  00  .00  .07  .37  .39  .11  .34  .14  .15  .04 

11 00  .00  .09  .22  ..50  .41  .20  1.09  .21  .18  .03 

13 00  .00  .04  .00  .19  .20  .05  .27  .11  .64  .03 

13 00  .00  .00  .00  .33  .01  1.02  1.22  .62  .43  .03 

14 00  .00  .00  .00  .07  .35  .39  .88  .43  .10  .00 

15 00  .02  .00  .21  .00  .08  .23  .46  .64  .09  .00 

16 00  .01  .00  .09  .01  .20  .35  .06  .72  .30  .14 

17 00  .00  .05  .07  .17  .27  .13  .08  .16  .24  .11 

18 00  .00  .00  1.49  2.12  .23  .17  .04  1.13  .03  .01 

19 00  .00  .00  .90  .78  .79  .23  .45  .30  .02  .00 

20 00  .06  .00  .88  .84  .27  .26  .32  .74  .08  .00 

21 00  .03  .03  .63  3.01  .35  .89  .98  .39  .03  .01 

33 00  .03  .00  1.96  1.31  .33  .09  .08  .08  .01  .05 

33 00  .08  .06     *      1.16  .06  .26  .28  .08  .01  .03  .00 

24 00  .33  .00  1.83  .94  .22  .03  .02  .33  .01  .00 

35 00  .05  .00  .24  .38  .21  .15  .01  .43  .26  .00 

26 00  .00  .09  .32  .42  .29  .31  .21  .29  .24  .03 

27 00  .00  .01  .15  .91  .11  .41  .43  .13  .07  .03 

38 00  .00  .00  .01  1.51  .33  1.00  .25  .40  .11  .55 

29 01  .00  .16  .16  .02  .51  .00  .08  .01  .09 

30 .00  .00  .18  .32  1.16  0.6  ...  .03  .00  .10 

31 .04  ...  .15  .04  .46  ...  .03  ...  .17 

.03  .93  .70  10.14  14.70  9.60  9.35  8.93  10.30  3.97  3.06 


270 


NICARAGUA  CANAL  COMMISSION 


MEAN  OF  DAILY  RAINFALL.— Continued. 

At  Ft.  San  Carlos  (January  1  to  March  31),  Las  Lajas  (January  1  to  March  31),  Tipitapa  (January  1  to 

January  23),  Rio  Viejo  (January  1  to  January  22),  Granada  (January  24  to  March  31),  1899. 


January. 

February. 

March. 

Day. 

Day. 

Day. 

Day. 

Day. 

Day. 

1.... 

.09 

17... 

.06 

1.... 

.00 

17.  . . . 

.44 

1.... 

.02 

17... 

.00 

2.... 

.00 

18... 

.06 

2.... 

.07 

18... 

.03 

2.... 

.00 

18... 

.00 

3.... 

.09 

19... 

.01 

o.  .  .  . 

.00 

19... 

.19 

3.... 

.02 

19... 

.00 

4 

.19 

20... 

.00 

4.... 

.03 

20... 

.02 

4.... 

.00 

20... 

.00 

5.... 

.05 

21... 

.06 

5.  .  .  . 

.00 

21... 

.02 

«).... 

.00 

21... 

.00 

6.  . . . 

.00 

22. . . 

.02 

6 

.08 

22.... 

.00 

6.... 

.04 

22. . . . 

.00 

7 

.01 

28... 

.02 

7.... 

.00 

23.... 

.01 

7.... 

.04 

23. . . . 

.00 

8 

.01 

24... 

.08 

KJ  ,    ... 

.01 

24.... 

.00 

8 .  .  .  . 

.07 

24. . . . 

.00 

9.... 

.10 

25... 

.02 

9.... 

.02 

25. . . . 

.00 

9.  . . . 

.00 

25. . . . 

.00 

10 

.04 

26... 

.03 

10.... 

.00 

26... 

.04 

10.... 

nOO 

26... 

.00 

11.... 

.04 

27. . . 

.02 

11 

.00 

27... 

.08 

11 

.00 

27... 

.00 

12.... 

.12 

28... 

.00 

12 

.18 

28... 

.00 

12 

.01 

28... 

.00 

13.... 

.03 

29... 

.03 

13.... 

.02 

13 

.00 

29... 

.00 

14 

.10 

30... 

.00 

14.... 

•00 

14 

.00 

30... 

.02 

15. . . . 

.08 

31... 

.07 

15.... 

.04 

15 

.03 

81... 

.24 

16.... 

.08 

16.... 

.04 

16 

.00 

1.51 

1.32 

0.49 

ACCUMULATED  RAINFALL  IN  THE  BASIN  OF  LAKE  NICARAGUA. 
Obtained  by  taking  the  mean  of  the  accumulated  rainfall  at  Ft.  San  Carlos  from  March  8, 1898,  to  March  31, 1899; 
Morrito  from  April  6,  1898,  to  August  31,  1898;  Tipitapa  from  February  7,  1898,  to  January  23,  1899; 
Rio  Viejo  from  February  1,  1898,  to  January  22,  1899;  Las  Lajas  from  February  1,  1898,  to 
March  31,  1899;   Granada  from  January  24,  1898,  to  March  31,  1899. 


^ 

Feb. 

Mar. 

Apr. 

Biay. 

June. 

July. 

Augr. 

Sept. 

Oct 

Nov. 

Dec. 

Jan. 

Feb. 

Mar. 

d 

1808. 

. 

1899. 

1 

•   •   •   • 

.02 

.94 

1.75 

11.68 

26.79 

36.23 

45.34 

54.19 

64.46 

68.65 

70.57 

72.12 

73.46 

2 

•   •   •   • 

.08 

.94 

1.78 

11.68 

27.51 

86.38 

45.63 

54.49 

64.46 

68.76 

70.57 

72.19 

73.46 

8 

•   •   •   • 

.17 

.95 

1.78 

11.69 

27.92 

86.43 

45.82 

54.87 

64.40 

68.79 

70.85 

72.19 

73.48 

4 

•   •   •   • 

.24 

.96 

1.80 

11.99 

28.07 

86.55 

45.91 

55.07 

64.70 

68.85 

70.86 

72.22 

73.48 

5 

•   •   •   • 

.24 

1.14 

1.88 

12.10 

28.11 

36.83 

46.25 

55.18 

64.75 

68.86 

70.91 

72.22 

73.48 

6 

•    •   •   • 

.24 

1.21 

1.88 

12.10 

28.45 

37.25 

46.47 

55.82 

64.75 

68.94 

70.91 

72.80 

73.52 

7 

•    •    •   • 

.24 

1.28 

1.88 

12.75 

28.61 

87.49 

46.69 

55.65 

64.78 

68.99 

70.92 

72.30 

73.56 

8 

•   •   •   • 

.30 

1.28 

1.88 

12.99 

28.75 

37.55 

46.85 

56.81 

64.99 

69.00 

70.93 

72.81 

73.63 

9 

.02 

.30 

1.28 

1.98 

18.19 

29.76 

87.90 

46.93 

57.26 

65.40 

69.09 

71.02 

72.83 

73.63 

10 

.02 

.30 

1.28 

2.05 

18.56 

80.15 

38.01 

47.27 

57.40 

65.55 

69.13 

71.06 

72.33 

73.63 

11 

.02 

.30 

1.87 

2.27 

14.06 

80.56 

38.21 

48.36 

57.61 

65.73 

69.10 

71.11 

72.33 

73.63 

12 

.02 

.30 

1.41 

2.27 

14.25 

80.76 

38.26 

48.63 

57.72 

66.87 

69.18 

71.23 

72.51 

78.64 

18 

.02 

.30 

1.41 

2.27 

14.57 

80.77 

89.28 

49.85 

58.34 

66.80 

69.20 

71.25 

72.53 

73.64 

14 

.02 

.30 

1.41 

2.27 

14.64 

81.02 

39.67 

50.78 

58.77 

66.90 

69.20 

71.25 

72.53 

73.64 

15 

.02 

.32 

1.41 

2.48 

14.64 

81.10 

39.90 

51.19 

59.41 

66.99 

69.20 

71.43 

72.57 

73.67 

16 

.02 

.33 

1.41 

2.57 

14.65 

81.30 

40.25 

51.25 

60.13 

67.29 

69.34 

71.43 

72.61 

73.67 

17 

.02 

.33 

1.46 

2.64 

14.82 

81.57 

40.88 

51.28 

60.29 

67.53 

69.45 

71.49 

73.05 

73.67 

18 

.02 

.33 

1.46 

4.18 

16.94 

81.80 

40.55 

51.32 

61.42 

67.56 

69.46 

71.65 

73.08 

78.67 

19 

.02 

.33 

1.46 

5.08 

17.72 

82.59 

40.78 

51.77 

61.72 

67.58 

69.46 

71.66 

73.27 

73.67 

20 

.02 

.39 

1.46 

5.41 

18.56 

82.86 

41.04 

52.09 

62.46 

67.66 

69.46 

71.60 

73.29 

73.67 

21 

.02 

.41 

1.48 

6.08 

20.57 

88.11 

41.95 

53.07 

62.75 

67.68 

69.47 

71.71 

73.81 

73.67 

22 

.02 

.43 

1.48 

7.98 

21.78 

88.34 

42.02 

53.15 

62.83 

67.69 

69.52 

71.78 

73.81 

78.67 

23 

.02 

.51 

1.54 

9.14 

21.84 

83.60 

42.30 

53.23 

62.84 

67.72 

69.52 

71.75 

78.32 

78.07 

24 

.02 

.84 

1.54 

10.47 

22.78 

88.82 

42.38 

53.25 

68.07 

67.78 

69.52 

71.87 

73.32 

73.67 

25 

.02 

.89 

1.54 

10.71 

28.16 

84.03 

42.48 

53.26 

63.50 

67.99 

69.52 

71.90 

73.32 

73.67 

26 

.02 

.89 

1.63 

11.08 

28.58 

84.32 

42.79 

53.47 

63.79 

68.23 

69.54 

71.95 

73.36 

73.67 

27 

.02 

.89 

1.64 

11.18 

24.49 

84.43 

43.20 

53.90 

63.91 

68.30 

69.57 

71.97 

73.44 

73.67 

28 

.02 

.89 

1.64 

11.19 

26.00 

84.76 

44.20 

54.15 

64.31 

68.41 

70.12 

71.97 

73.44 

73.67 

29 

•    •   •   • 

.90 

1.64 

11.85 

26.16 

84.78 

44.71 

54.15 

64.39 

68.42 

70.21 

72.02 

•   •   •   • 

73.67 

80 

•    •   •   • 

.90 

1.64 

11.58 

26.88 

85.94 

44.77 

54.15 

64.42 

68.42 

70.31 

72.02 

•   •   •    • 

73.69 

31 

•    •    •   • 

.94 

•   •  •   • 

11.68 

•  •  •  •  • 

85.98 

45.23 

•   •   •   • 

64.45 

•  •   •   • 

70.48 

72.12 

•    •   •   • 

78.98 

APPENDIX   III.— HYDROGRAPHIC   REPORT 


271 


DAILY  RAINFALL  AT  SABALOS  ABOVE  TORO  RAPIDS. 


Day.  Feb 
1898 

Mar. 

• 

April. 

May. 

June. 

July. 

Aug. 

Sept. 

Oct. 

Nov. 

Dec. 

Jan. 

1899. 

Feb. 

Mar. 

1..      .. 

.00 

.13 

1.34 

.07 

1.32 

.00 

.02 

.03 

.00 

1.75 

.76 

.02 

.22 

o 

.00 

.00 

.08 

.00 

1.78 

.95 

.02 

.58 

.00 

.06 

.12 

.06 

.00 

8..      .. 

.00 

.00 

.00 

.00 

1.68 

.42 

.10 

.52 

.03 

.09 

.32 

.00 

.06 

4..      .. 

.23 

.47 

.00 

.23 

.56 

.00 

.11 

.38 

.20 

.00 

.94 

.00 

.00 

5..      .. 

.18 

2.41 

.52 

.00 

.40 

.00 

.00 

.10 

.17 

.15 

.68 

.14 

.00 

6..      .. 

.00 

.29 

.00 

.00 

.00 

1.78 

.82 

.14 

.02 

.25 

.13 

.24  . 

.02 

7..      .. 

.00 

.00 

.73 

.36 

.15 

.21 

1.07 

.04 

.10 

.47 

.42 

.00 

.85 

8..      .. 

.30 

.00 

.02 

.00 

.20 

.04 

.05 

.96 

.12 

.55 

.39 

.00 

.91 

9..      .. 

.00 

.00 

.00 

.50 

.86 

.95 

.83 

.09 

.40 

.48 

.71 

.04 

.16 

10..      .. 

•   • 

.05 

.25 

1.26 

.86 

.64 

.00 

.04 

.42 

1.30 

.82 

.00 

.03 

11..      .. 

•   • 

.85 

3.05 

.05 

.82 

.32 

1.52 

•02 

.12 

.01 

.17 

.08 

.07 

13..      .. 

•   • 

.22 

.00 

.12 

1.45 

.15 

2.61 

.90 

1.59 

.03 

1.38 

1.54 

.08 

13..      .. 

.00 

.00 

.17 

.12 

.12 

.79 

.57 

.13 

2.74 

.12 

.22 

.01 

.14 

14..      .. 

.00 

.00 

.00 

.86 

.12 

.15 

.26 

.09 

.13 

.00 

.93 

.01 

.16 

1.5..      .. 

.00 

.00 

.42 

.06 

.00 

.45 

.39 

.21 

.23 

.00 

.36 

.27 

.00 

16..      .. 

.01 

.00 

.00 

.05 

.78 

.01 

1.67 

.01 

2.14 

l.,56 

.33 

.11 

.00 

17..      .. 

.00 

.84 

.15 

•00 

.86 

.00 

.00 

8.18 

1.30 

1.25 

.00 

.67 

.11 

18..      .. 

.00 

.00 

1.07 

2.82 

.31 

.07 

.00 

.67 

.04 

.14 

.38 

.08 

.00 

19..      .. 

.00 

.00 

.43 

.65 

.65 

.27 

.17 

.58 

.00 

.00 

.00 

.09 

.00 

20..      . 

.03 

.00 

.04 

.57 

2.22 

.30 

.04 

1.40 

.19 

.00 

.09 

.03 

.00 

21.. 

.09 

.03 

.00 

.31 

1.52 

1.23 

.58 

•83 

.00 

.20 

.03 

.12 

.04 

.00 

22 . . 

.07 

.11 

.05 

.09 

1.76 

.48 

.19 

.22 

.10 

.03 

.12 

.27 

.00 

.04 

23.. 

.77 

.28 

.27 

.35 

.43 

.00 

.57 

.33 

.11 

.00 

.00 

.05 

.00 

.00 

24.. 

.00 

.64 

.00 

.00 

.62 

.42 

.32 

.00 

.22 

.16 

.00 

.20 

.62 

.00 

25.. 

.68 

.18 

.00 

.25 

1.48 

.90 

.51 

.00 

.38 

.42 

.00 

.00 

.04 

.00 

26.. 

.23 

.00 

.27 

.00 

1.42 

.90 

.00 

.00 

.66 

.56 

.00 

.05 

.00 

.00 

27.. 

.07 

.04 

.14 

.80 

.31 

.11 

.06 

.26 

.01 

.26 

.07 

.00 

.08 

.00 

28. 

.00 

.00 

.00 

.16 

1.11 

1.73 

.00 

.03 

.04 

.57 

.13 

.00 

.16 

.00 

29.. 

•   • 

.07 

.00 

1.11 

1.76 

.07 

.36 

.00 

.00 

.02 

.33 

.01 

•   • 

.00 

30.. 

•   • 

.00 

.01 

.00 

.00 

.27 

.87 

.00 

.25 

.01 

.87 

.00 

•   • 

.00 

31.. 

•    • 

.00 

•   • 

.30 

•  • 

.00 

.37 

•   • 

.02 

•   • 

.34 

.02 

•   • 

.38 

1.91 

2.10 

6.00 

11.69 

17.13 

20.69 

11.33 

11.42 

11.81 

12.17 

10.20 

9.82 

4.33 

2.73 

DAILY  RAINFALL  AT  CASTILLO.  ON  SAN  JUAN  RIVER. 


Day. 

1888. 
June. 

July. 

Aug. 

Sept. 

Oct. 

Nov. 

Dec. 

1899. 
Jan. 

Feb. 

Mar. 

1 

1.75 

.18 

.00 

.00 

.00 

1.38 

.55 

.13 

.36 

2 

1.81 

.61 

.00 

1.83 

.00 

.58 

.46 

.01 

.00 

3 

1.45 

.18 

.00 

.00 

.00 

.02 

.40 

.05 

.07 

4 

.12 

.35 

.00 

.00 

.14 

.00 

.76 

.20 

.02 

5 

.77 

1.23 

.00 

.00 

.17 

.13 

1.19 

.07 

T. 

6 

.01 

.27 

.00 

•   •   •  • 

.00 

.27 

.03 

.60 

.00 

7 

.00 

.27 

.36 

•   •   •   • 

.00 

.89 

.30 

T- 

.00 

8 

.18 

.13 

1.87 

.00 

.00 

.00 

.40 

.00 

.00 

9 

1.48 

.74 

.27 

.83 

1.86 

.80 

1.15 

.01 

.41 

lu 

.20 

.57 

.13 

.15 

.13 

1.38 

.07 

.05 

.27 

272 


NICARAGUA  CANAL  COMMISSION 


DAILY  RAINFALL  AT  CASTILLO.  ON  SAN  JUAN  RIVER.— Continued. 


Day. 

June. 
1896. 

July. 

Aug. 

Sept. 

Oct. 

Nov. 

Deo. 

Jan. 
1899. 

Feb. 

Mar. 

11 

■   •          •    ■   •  • 

.89 

.41 

8.78 

.00 

.07 

.27 

.55 

.05 

.00 

12 

1   •          •   •   •   • 

.05 

.84 

.08 

.00 

1.07 

.21 

1.85 

2.00 

.01 

lo 

.        .40 

.13 

.18 

.21 

.00 

8.18 

.08 

.82 

.00 

T. 

14.... 

*   *          •   •   •   • 

.11 

1.15 

.09 

.00 

.02 

'  .00 

.59 

.01 

.19 

15 

•          •   •   •  • 

.18 

.80 

.28 

.00 

.06 

.08 

.17 

.21 

.00 

16 

•          •   •   ■   • 

.27 

.18 

2.51 

.00 

2.80 

.40 

.27 

.98 

.18 

17 

•          •   •  •   • 

.67 

.00 

.05 

.80 

2.29 

2.85 

.21 

.82 

.16 

18 

•          •   •   •   • 

.71 

.00 

.00 

.87 

.00 

.27 

.40 

.52 

.00 

19 

.     1.25 

•1.10 

.00 

.00 

.00 

.08 

.01 

.00 

.15 

.00 

20 

.     2.18 

.89 

.86 

.11 

.85 

.10 

.00 

.21 

.08 

T. 

21 

.88 

1.68 

.70 

.88 

.01 

.15 

.02 

.08 

.00 

.02 

22 

.      1.25 

.25 

.08 

4.05 

.03 

.01 

.00 

.00 

.01 

.01 

23 

.     . . .  • 

.94 

.00 

.54 

.00 

.01 

.00 

.00 

.18 

.05 

24 

.      1.00 

.08 

.17 

.00 

.29 

.04 

.00 

.84 

.85 

.00 

25 

.     1.14 

.21 

.67 

.00 

.40 

.51 

.00 

.00 

.00 

.03 

26 

.       .18 

.40 

.23 

1.01 

.08 

1.01 

.00 

.00 

.01 

.00 

27 

.58 

.17 

.00 

.00 

.00 

.76 

.00 

.00 

.07 

T. 

28 

.       .16 

2.26 

.37 

.00 

.02 

.59 

.00 

.00 

.06 

.00 

29 

.     1.50 

.81 

.39 

.00 

.00 

.04 

.00 

.01 

•   •   •   • 

.00 

80 

.00 

.00 

.00 

.00 

.00 

.00 

1.94 

.01 

•   •   •  • 

.00 

81 

«          •   •  •   ■ 

.00 

.00 

•    •    •    • 

.08 

•   •   •  • 

.54 

T. 

«    •   ■   • 

.29 

Total 

B..  10.47 

18.92 

11.46 

16.22 

4.64 

14.04 

11.57 

10.32 

6.47 

2.02 

DAILY  RAINFALL  AT  MACHUCA, 

ON  SAN  JUAN  RIVER. 

Day. 

July. 
1898. 

Aug. 

Sept. 

Oct 

Nov. 

Dec. 

Jan. 

1889. 

Feb. 

Mar. 

1 

•  ■   • 

•  •   • 

•  •   • 

.37 

.84 
.00 

.00 
.25 
.75 

.00 
2.05 

.12 

.00 
.00 
.00 

1.83 
.00 
.00 

.84 
.65 
.74 

.00 
.22 
.00 

.00 

2 

.00 

8 

.00 

4 

•  •   • 

•  •   • 

.00 
.50 

.00 
.00 

.31 
.50 

.56 
.00 

.00 
.47 

.84 
1.74 

.00 
.00 

.00 

5 

.00 

6 

•  •   • 

•  •   • 

•  •   • 

.00 
.56 
.62 

.12 
.00 
.00 

.25 
.00 
.00 

.00 
.12 
.00 

.00 
.75 
.00 

.00 
.25 

.87 

.00 
.00 
.00 

.00 

7 

.00 

8 

.87 

9 

•   •    • 

.40 
.15 

.22 

.78 

.09 

.43 
.00 

1.18 

.37 
.00 

.00 

2.24 
.00 

.00 

.00 
2.52 

.00 

.48 
.25 

.74 

.49 
.00 

.00 

.25 

10.    ... 

.00 

11 

.00 

13 

.12 
.53 
.12 

.25 
.81 
.09 

.00 

1.38 

.09 

.40 
.87 
.00 

1.24 
.87 
.00 

.00 
.00 
.00 

2.78 
.59 

.71 

1.86 
.00 
.00 

.00 

13.    ... 

.00 

14 

.00 

15 

.09 

.06 
.00 
.59 
.37 

1.06 

.00 
.25 
.00 
.00 

.09 

1.27 
.06 
.09 

.28 

.00 

.00 

.00 

8.07 

1.24 

.25 

2.78 

1.55 

.06 

.00 

.00 

1.08 
.00 
.00 
.00 

.25 

.65 
.00 
.00 
.00 

.46 

.19 
.58 
.62 
.12 

.00 

16 

.22 

17 

.00 

18 

.00 

19 

.00 

20 

1.12 

.00 

.00 

.00 

.56 

.15 

.84 

.00 

.00 

APPENDIX  III.— HYDROGRAPHIC   REPORT 


273 


DAILY  RAINFALL  AT  MACHUCA,  ON  SAN  JUAN  RIVER. —Continued. 


Day. 

July 
1896. 

Aug. 

Sept. 

Oct. 

Nov. 

Dec. 

Jan. 
1W9. 

Feb. 

Mar. 

21   

1.15 

.87 

.75 

.00 

.06 

.00 

.00, 

.00 

.00 

255 

.12 

00 

1.68 

.00 

.00 

.00 

.34 

.00 

.00 

23 

# 

.06 
.62 

.03 
.09 

1.33 
.00 

.06 
.81 

.00 
.81 

.00 
.00 

.00 
.00 

.00 
.12 

.00 

24 

.00 

26 

.47 

.09 
.00 

.40 

.25 

.00 

.00 

1.83 
1.83 

.00 

.00 
.00 

.43 

1.43 
.56 

.00 

.00 
.00 

.00 

.00 
.21 

.00 

.00 
.00 

.00 

26 

.00 

27 

.00 

28 

.12 

.00 

.00 

.03 

2.18 

•    • 

.00 

.00 

.00 

29 

.28 
.06 

.09 
.00 

.00 
.00 

.00 
.25 

.50 
.00 

•    • 
■    • 

.00 
.00 

• 
•   • 

.00 

30 

.00 

81 

.00 

.34 

•  « 

.00 

•   • 

■     • 

•   • 

•  • 

.31 

Totals. . 

6.52 

8.51 

12.86 

9.83 

15.65 

6.75 

13.17 

4.61 

1.65 

DAILY  RAINFALL  ON  SAN  CARLOS  RIVER,  1898. 

Day. 

Feb. 

Mar. 

Apr. 

May. 

June. 

July. 

Aug, 

1 

.04- 

.10 

. 

l.U 

1.17 

1.28 

.83 

2 

Trace 

.04 

.02 

.01 

1.76 

2.59 

8 

.00 

.02 

.16 

.00 

1.13 

.02 

4 

.70 

.76 

!.73 

.00 

.94 

.07 

5 

1.26 

3.63 

.45 

.00 

1.20 

54 

6 

.02 

1.80 

.06 

.08 

.01 

06 

7 

.14 

.oW 

.00 

.60 

.00 

.45 

8 

.06 

.06 

.05 

.15 

1.11 

.61 

9 

.89 

.00 

.42 

.00 

1.07 

.89 

10 

.10 

.30 

.68 

.69 

1.94 

.01 

11 

.00 

.48 

1.53 

.17 

.22 

.34 

12 

.10 

.34 

.03 

.01 

.04 

.51 

13 

.00 

.04 

.11 

2.06 

.00 

1.48 

14 

.00 

.02 

1.23 

.32 

.09 

.21 

16 

.00 

.00 

.87 

.23 

.00 

.20 

16 

)0 

.00 

.00 

.04 

.02 

.00 

.34 

17 

)2 

.04 

.00 

.05 

.00 

.00 

.45 

18 

L5 

.09 

.28 

1.18 

.60 

1.05 

.00 

19 

)0 

.00 

.39 

2.86 

1.37 

.19 

.00 

20 

12 

.24 

.00 

.56 

1.32 

1.41 

.50 

21 

)0 

.71 

.02 

1.99 

.57 

.73 

.69 

22 

S4 

.87 

.10 

.19 

1.95 

.00 

.00 

23 

)4 

.02 

.80 

.43 

2.82 

.17 

.94 

24 . 

{3 

.36 

.49 

.00 

.64 

.74 

.00 

25 

$7 

.90 

.07 

.00 

1.57 

1.09 

.00 

26 

1.) 

L4 

.48 

.33 

.06 

.61 

.36 

.82 

27 

l.( 

)2 

.87 

.10 

.18 

1.22 

.10 

.13 

2S 

)5 

.08 

.00 

.26 

1.42 

.02 

.00 

29 

■   • 

.00 

.00 

.24 

1.06 

1.59 

.00 

30 

>   • 

.08 

.00 

.43 

.13 

.02 

.00 

31 

>   • 

.00 

»   • 

3.22 

•   • 

.00 

.00 

Total . . . 

4J 

83 

7.52 

11.66 

20.12 

20.79 

18.26 

11.68 

18 


274 


NICARAGUA   CANAL  COMMISSION 


DAILY  RAINFALL  AT  OCHOA,  ON  SAN  JUAN  RIVER. 


Day. 

Jhd. 
1898. 

Feb. 

Mar. 

Apr. 

Mtf>'. 

June. 

July. 

Augr. 

Sept. 

1 

Oct. 

Nov. 

Dec. 

Jim. 

1899. 

Feb. 

Mar. 

1 

.01 

.87 

,03 

.13 

1.35 

.SO 

1.07 

1.20 

.21 

1.17 

.00 

.79 

1.17 

.37 

.35 

2.... 

.05 

2.73 

.00 

.03 

.13 

.01 

3.81 

.20 

.44 

.00 

.05 

1.83 

.11 

.01 

3.... 

.28 

1.23 

.00 

.03 

.01 

.00 

.63 

.01 

.04 

.00 

.26 

.07 

.59 

.08 

.14 

4.... 

.06 

1.67 

.52 

1.91 

1.49 

.00 

1.73 

.03 

.11 

.53 

.63 

.32 

.84 

.01 

.05 

5.  . . . 

.71 

.61 

1.75 

3.97 

.79 

.00 

.30 

.71 

.17 

.83 

.31 

.18 

1.31 

.18 

.00 

C.  . . . 

.51 

.01 

.08 

1.80 

.13 

.15 

.01 

.04* 

.14 

.23 

.53 

.03 

.05 

.23 

.02 

7.... 

.73 

.00 

.17 

.35 

.01 

.43 

.01 

.29 

.14 

.00 

.26 

.15 

.67 

.00 

1.36 

8 

.34 

1.50 

.10 

.34 

.31 

.16 

1.03 

.54 

.13 

.01 

3.19 

.20 

.25 

.00 

2.51 

9 

1.37 

.17 

.8y 

.00 

.14 

.01 

1.11 

.89 

.12 

.09 

.13 

.63 

.17 

.11 

.06 

10.... 

1.04 

.18 

.03 

.39 

.63 

.01 

1.68 

.01 

.00 

.03 

.33 

1.83 

.33 

.17 

.00 

11.... 

.03 

.09 

.00 

.60 

1.19 

.13 

.09 

.23 

1.76 

.05 

.07 

1.00 

.54 

.08 

.05 

12.... 

.20 

.76 

.00 

.15 

.01 

.01 

.05 

.41 

1.26 

.03 

3.16 

.04 

1.38 

.99 

.03 

13.... 

.19 

.11 

.00 

.03 

.00 

3.06 

.11 

1.74 

1.61 

.19 

.78 

.31 

.34 

.49 

.35 

14 

.05 

.05 

.00 

.03 

.33 

.33 

.00 

.30 

.44 

.03 

.33 

.03 

.24 

.01 

.36 

15.... 

.51 

00 

.03 

.00 

.53 

.48 

.07 

.03 

.00 

.08 

1.38 

.01 

1.49 

.13 

.34 

16.... 

1.05 

.09 

.00 

.00 

.03 

.03 

.03 

.07 

.06 

.14 

5.10 

.33 

.80 

.58 

.09 

17.... 

1.18 

.07 

.09 

.07 

.13 

.01 

.17 

.35 

.01 

.09 

2.17 

.57 

.01 

.33 

.09 

18.... 

.42 

.00 

.00 

.47 

.36 

2.58 

.64 

.01 

.86 

.92 

.27 

.09 

.43 

.95 

.01 

19.... 

.02 

.15 

.00 

.43 

1.66 

1.39 

.19 

.01 

.14 

.11 

.02 

.01 

.16 

1.45 

.00 

20.... 

.47 

.44 

.35 

.00 

.37 

1.38 

1.84 

.03 

.00 

.00 

.07 

.08 

.22 

.37 

.00 

21.... 

2.13 

.01 

.15 

.00 

3.34 

.93 

1.21 

1.18 

1.34 

.88 

.14 

.01 

.54 

.33 

.02 

22.... 

.26 

.14 

.41 

.43 

.06 

.33 

.01 

.01 

2.25 

.15 

.01 

.00 

.44 

.09 

.00 

23.... 

.01 

.07 

.03 

1.15 

.42 

3.36 

1.00 

2.01 

.54 

1.55 

.03 

.03 

.04 

.16 

.00 

24.... 

.02 

.26 

.36 

.07 

.00 

1.12 

.59 

.29 

.00 

.09 

.34 

.00 

.34 

.06 

.00 

25.... 

.35 

.69 

1.35 

.00 

.00 

2.70 

1.62 

.05 

.23 

.39 

.49 

.00 

.03 

.05 

.00 

26.... 

.36 

.61 

.30 

.75 

.08 

.56 

2.43 

.28 

2.01 

.23 

1.11 

.73 

.04 

.06 

.00 

27.... 

.23 

.93 

1.21 

.11 

.76 

.57 

.02 

.06 

.10 

.08 

.83 

.11 

.01 

.33 

.01 

28 

.20 

.66 

.05 

.01 

.11 

.33 

.07 

.00 

.00 

.00 

.94 

.00 

.00 

.35 

.02 

29.... 

.29 

•   •   •   • 

.08 

.03 

.12 

1.73 

1.04 

.04 

.03 

.00 

.72 

.24 

.03 

•   •  •   • 

.00 

80.... 

.03 

•  •  •   • 

.00 

.10 

.05 

.10 

.06 

.15 

1.23 

.15 

.02 

.40 

.00 

•   •   •   • 

.01 

81 

.00 

•    •   •    • 

.15 

•   •  •   • 

1.96 

•  •  •   • 

.00 

.29 

•  •   •  • 

.04 

•   •   •   • 

.17 

.05 

•    •   •   • 

.33 

13.07 

14.08 

8.04 

13.33 

15.25 

31.47 

21.60 

12.08 

15.13 

8.02 

21.50 

8.38 

14.03 

7.90 

5.80 

DAILY  RAINFALL  AT  STATION  ON  THE  RIO  SAN  FRANCISCO,  1898. 


Day. 

Jan. 

Feb. 

Mar. 

April. 

May. 

June. 

July. 

Aug. 

Sept. 

Oct. 

Nov. 

Dec. 

1 

•    •   •   • 

1.26 

.05 

.07 

1.94 

.58 

.83 

.97 

.16 

.15 

.00 

1.03 

2 

•   •   •   • 

3.74 

.00 

.03 

.17 

.00 

3.84 

1.11 

.31 

.76 

.00 

.07 

8 

•   •  •   • 

1.70 

.00 

.01 

.09 

.00 

1.06 

.01 

.30 

.09 

.00 

.10 

4 

•   •   •   • 

1.66 

.57 

1.94 

1.22 

.00 

1.37 

.37 

.00 

.32 

.71 

.09 

5 

•   •  •  • 

1.03 

1.54 

3.35 

.66 

.11 

.55 

.03 

.00 

.35 

07 

.34 

6   

.10 

.01 

.06 

.74 

.35 

.00 

.00 

.00 

.42 

.29 

.60 

.60 

7 

1.08 

.00 

.37 

.80 

.00 

.08 

.OtJ 

1.24 

.16 

.10 

.93 

.17 

8 

.28 

8.83 

.03 

.32 

.19 

.00 

.78 

.86 

.17 

.02 

4.07 

.38 

9 

2.10 

.18 

1.35 

.01 

.22 

.13 

.38 

1.02 

.18 

1.03 

.35 

.73 

10 

1.03 

.38 

.03 

.25 

.46 

.08 

1.41 

.01 

.01 

.18 

.30 

2.28 

11 

.05 

.17 

.00 

.89 

1.51 

.88 

.09 

1.48 

1.07 

.09 

.04 

1.30 

12 

.29 

.93 

.03 

.46 

.02 

.00 

.10 

.55 

2.19 

.40 

.82 

.00 

13 

.44 

.11 

.00 

.11 

.00 

2.59 

.00 

1.40 

.61 

.57 

1.64 

.84 

X^ •   •        •  •  •   •   • 

.18 

.03 

.00 

.15 

.00 

.29 

.19 

.27 

.88 

.06 

.66 

.02 

15 

.50 

.00 

.45 

.00 

1.26 

.45 

.08 

.09 

.17 

.05 

.78 

.16 

NICARAGUA  CANAL  CCMMJSSION 


i 

J 

NUARY              FEBWUA 

RY                MARCH 

PR 

L 

MAY 

JU 

! 

•MA-C  8 

A 

u 

J 

1 

1 

.  Jl  ,1 

1      ll  1 

3  ll-Qf^ 

1 

1 

ll 

1 

nJ 

Hi 

imlli 

u 

.11 

I, 

ll 

Li 

.1 

Ll    J    Jl 

iL  I 

O 

'I  Y  rovrr 

ll 

t1 

II 

1 

o 

li 

Ik 

11 

4 

il 

IJ 

nL 

Jjl 

[i.L 

iiiiy 

TEBBUARY 


COMPARATIVE  DIAGRAMS   OP  RA 


APPENDIX  III.— HYDROGRAPHIC   REPORT 


275 


DAILY  RAINFALL  AT  STATION  ON  THE  RIO   SAN  FRANCISCO.  1898.— Continued. 


Day. 

Jan. 

Feb. 

Mar. 

April. 

May. 

June. 

July. 

Aug. 

Sept. 

Oct. 

Xov. 

Dec. 

16 

1.11 

.16 

.25 

.00 

.03 

.01 

.08 

.00 

.00 

.07 

5.26 

.32 

17 

1.60 

.07 

.09 

.06 

.27 

.19 

.10 

.14 

.00 

.00 

1.55 

.42 

18 

1.04 

.00 

.02 

.74 

.31 

.19 

1.13 

.00 

.27 

.47 

.23 

.16 

19 

.01 

.16 

.01 

.67 

.71 

3.02 

.26 

.30 

.27 

.03 

.00 

.00 

20 

.81 

.28 

.18 

.01 

.37 

.17 

1.46 

.25 

T. 

.00 

.11 

.00 

21 

2.07 

.06 

.27 

.00 

1.45 

.17 

1.45 

.20 

1.74 

.88 

.07 

.00 

22 

.81 

.00 

.39 

.30 

.14 

1.02 

.00 

.01 

.30 

.22 

.05 

.31 

28 

.00 

.08 

.02 

.96 

.45 

.39 

.57 

1.33 

1.85 

1.58 

.09 

.10 

24 

.55 

.23 

.46 

.33 

.00 

3.01 

.82 

.17 

.04 

.25 

.27 

.00 

25 

.31 

.40 

.87 

.00 

.00 

2.04 

2.17 

.14 

.00 

.69 

.51 

.00 

26 

.70 

.86 

.24 

.26 

.19 

1.92 

.45 

.66 

.08 

.12 

.89 

.84 

27 

.08 

1.17 

1.25 

.24 

.09 

.78 

.04 

.79 

.06 

.18 

.90 

.26 

28 

.05 

.71 

.02 

.02 

.00 

.28 

.36 

.00 

.00 

.05 

1.88 

.00 

29 

.63 

.16 

.00 

.55 

.99 

.52 

.05 

.21 

.00 

.10 

•  •   • 

80 

.07 

.01 

.03 

.00 

.00 

.13 

.06 

.00 

.07 

.00 

•  •   • 

81 

T. 

.23 

1.33 

.00 

.04 

.02 

•  •   ■ 

Totals.. 

14.88 

18.43 

8.72 

11.35 

13.87 

18.87 

19.23 

13.45 

10.95 

9.09 

33.38 

9.80 

DAILY  RAINFALL  ON  RIO  SARAPIQUI,  FIVE  MILES  ABOVE  ITS  MOUTH. 


Day. 

July 

18JW 

AuiJTiiSt. 

September. 

October. 

November. 

December. 

January. 
IWW. 

February. 

March. 

1 

.50 

.54 

.00 

.00 

.64 

.82 

.35 

.24 

2 

2.10 
.10 

.39 
.04 

.00 
.03 

.00 
.00 

.07 
.07 

1.17 
1.74 

.01 
.03 

.08 

8 

.31 

4 

.  .  .  . 

.05 

.01 

.86 

.49 

.18 

1.17 

.00 

.03 

5 

.00 
.00 

.86 
.50 

.36 

1.07 

1.09 
.16 

.45 
.00 

.35 

.04 

.00 

6 

.01 

7 

.33 

.63 

1.18 

.06 

1.15 

.00 

1.07 

8 

.11 

.02 

2.51 

.31 

.26 

.00 

1.73 

9 

.00 

.12 

.00 

.54 

.54 

.00 

.18 

10 

.18 

.25 

.14 

1.65 

.30 

.54 

.04 

11 ■ 

.75 

1.05 

.09 

.44 

.95 

.30 

.00 

12 

.00 

.68 

.36 

.03 

-  1.66 

1.61 

.07 

13 

3.35 

.28 

.29 

.08 

1.05 

.72 

.53 

14 

.41 

.08 

.36 

.08 

.31 

.05 

.12 

15 

.30 
.01 

.04 
.15 

.76 
2.15 

.00 
.19 

1.83 
1.09 

.13 
.09 

.34 

16 

.13 

17 

.03 

.13 

3.75 

.41 

.07 

.22 

.07 

18 

1.45 

T. 

.95 

.06 

.56 

.76 

.16 

19 

.00 

.04 

.35 

.01 

.00 

.06 

.66 

.01 

20 

1.02 

.00 

.00 

.00 

.01 

.40 

.38 

.00 

21 

.01 

3.44 

.00 

.07 

.00 

.11 

.11 

.01 

22 

.00 
.19 

.00 
1.16 

1.79 
2.15 

.00 
.01 

.16 
.23 

.07 
.10 

.03 
.46 

.00 

23 

.00 

24 

.04 

.01 

.26 

1.35 

.00 

.59 

.36 

.18 

25 

.00 

.00 

.84 

.16 

.00 

.05 

.00 

.00 

276 


NICARAGUA  CANAL  COMMISSION 


DAILY  RAINFALL  ON  RIO  SARAPIQUI,  FIVE  MILES  ABOVE  ITS  MOUTH.— Continued. 


Day. 

July. 

Auifust. 

Soptembcr. 

October. 

N<»veml)cr. 

l>eoeml)er. 

January. 

IHW. 

February. 

March. 

26 

.15 

.00 

.00 

.17 

.39 

.23 

.03 

.19 

.00 

27 

.12 

.00 

.05 

.03 

1.05 

.07 

.04 

.05 

.00 

28 

.05 

.17 

.00 

.00 

.78 

.00 

.00 

.08 

.00 

29 

.10 

.08 
.00 

.80 
.00 

.00 
.03 

.33 
.02 

.12 
.21 

.00 
.00 

.... 
.... 

.00 

80 

.93 

.01 

31 

.90 

.10 

•   •   •   • 

.0(5 

•    •   •    • 

.OS 

.01 

.... 

.35 

4.30 

11.19 

11.35 

18.03 

7.10 

10.57 

1.  <   1 

5.07 

Day 


DAILY  RAINFALL  OF  RIO  DESEADO  AT  CAMP  BARTON  FOR  1898. 


Jan. 


Feb. 


Mar.       April. 


May. 


June. 


July. 


Augr.        Sept. 


Oct. 


Nov. 


Dec. 


1. 

o 

<M  < 

3. 
4. 
5. 

6. 

7. 

8. 

9. 

10, 

11. 
12. 
18. 
14. 
15. 

16. 

17. 
18. 
19. 
20. 

21. 
22. 
23. 
24. 
25. 

26. 

37 

28. 

39. 

80. 

81. 


.14 
.15 
.92 
.38 
1.23 

.46 
1.91 

.45 
3.66 
1.24 

.98 
.20 
.84 
.00 
1.21 

1.91 

1.08 

.76 

.09 

.59 

1.69 
.50 
.03 
.57 
.53 

.78 
.36 
.18 
.80 
.25 
.08 


.86 
4.61 
1.70 
4.37 
1.31 

.00 
.00 
1.82 
.21 
.95 

.49 
1.13 
.32 
.08 
.00 

.18 
.40 
.00 
.28 
.81 

.10 
.88 
.68 
.26 
1-88 

1.08 
8.04 
1.29 


.03 
.08 
.00 
.26 
1.49 

oo 

.  WW 

.09 

.68 

2.60 

.02 

.04 
.08 
.00 
.06 
.00 

.04 
.17 
.00 
.02 
.84 

.12 

.81 

.29 

1.05 

1.75 

.37 
.98 
.03 
.87 
.35 
.28 


.19 

.00 

.07 

1.80 

2.33 

.89 
.22 
.19 
.14 
.29 

.51 
.10 
.01 
.07 
.00 

.00 
.02 
.01 
.13 
.00 

.00 
.77 
1.06 
.18 
.00 

.73 
.17 
.00 
.01 
.00 


1.78 

.29 

.01 

1.29 

1.05 

.82 
.02 
.04 
.08 
.57 

.91 
.06 
.07 
.01 
.00 

.75 
.47 
.09 
1.44 
.07 

1.22 
.11 
.45 
.00 
.00 

.00 
.05 
.00 

1.01 
.08 

2.60 


.76 
.00 
.00 
.00 
.38 

.03 
.63 
.00 
.69 
.00 

.99 

.08 

2.48 

1.22 

.50 

.25 
.01 
.00 
.99 

.87 

.34 

.01 

2.06 

2.10 

.92 

.09 
.38 
.88 
3.04 
.13 


3.70 
2.48 
1.08 


.00 
1.06 
1.44 

.80 

.15 
.02 
.02 
.07 
.00 

.24 

.67 

.76 

1.55 

3.83 

3.69 
.08 
.81 
.18 
.77 

.37 
.90 
80 
.83 
2.02 
.00 


2.06 

1.8S 

.11 

.51 

.21 

.00 
1.77 

.94 
1.84 

.87 

.03 
1.37 
.28 
.29 
.00 

.00 
.00 
.00 
.04 
.08 

.28 
.12 
.00 
.00 
.37 

.52 
.01 
.00 
.19 
.00 
.09 


.74 
.10 
..58 
.20 
.07 

.15 
.20 
.68 
.00 
.84 

.54 
.21 
.81 
.07 
.00 

.00 
.00 
.10 
.24 
.00 

.09 
.00 
.03 
.00 
.02 

.00 
.00 
.00 
.00 
.00 


.00 
.42 
.51 
.58 
.09 

.68 

.00 

.04 

2.30 

1.07 

.97 
.03 
.28 
.30 
.44 

.18 
.00 
.00 
.80 
.00 

.03 
.03 

1.87 
..56 

1.30 

.08 
.00 
.30 
.00 
.10 
.00 


.70 
.00 
.00 
.25 


-{   2.96 


1.11 

1.02 
.30 

2.70 
.58 

1.88 

5.80 

8.61 

.74 

.01 

.85 

.22 
.09 
.08 
.85 
.68 

2.80 

1.87 

1.44 

.30 

.00 


2.75 
.49 
.07 
.11 
.11 

.67 

.69 

.40 

1.66 

1.65 

1.88 
.02 
.21 
.00 
.28 

.91 
.45 
.02 
.00 
.00 

.10 
.44 
.01 
.00 

1S97 

1.13 

2.27 
1.35 
1.66 
1.60 
.69 


Totals 


21.92 


26.98 


11.70 


8.83 


14.84 


18.00 


26.27 


13.31 


5.23 


11.92 


21.0'; 


NICARAGUA  CANAL  C0MMIB8I0N 


LAS         I.^JM 

_       1   _. 

An 

F>n      SMI      :3>kFL3ii 

X    JJ^. 

.lLI.uJj  iilJ 

t  At.      -||>.MC  IIIC  C 

ll 

1 

1 

. 

M 

u 

i.LL 

ilILL.Ju.i, 

EBRUARY  MARCH  APRIL  MAY  JUNE 

DIAGRAM  OF  THE  DAILY  RAINFALL  AT  LAS 


8EPTEMBE 


APPENDIX  3,  PLATE  XIV 
NOVEMBER  DCCCUBCH 


JULY  AUGUST  SEPTEMBER  OCTOBER 

FT.  SAN  CARLOS  AND  RIO  SAN  FRANCISCO,  1898. 


APPENDIX   III.— HYDROGRAPHIC   REPORT 


277 


DAILY  RAINFALL  AT  GREYTOWN,  NICARAGUA. 


Day. 

Jan. 

18M8. 

Feb. 

Mar. 

Apr. 

• 

May, 

June. 

July. 

Aug, 

Sept. 

Oct. 

Xov. 
.27 

Dec. 

Jan. 
JnBli. 

Fob. 

Mar. 

Apr. 

1 

.42 

.61 

.13 

.00 

1.90 

2.17 

.00 

2.28 

.00 

.00 

2.91 

1.44 

.08 

.52 

.27 

2.... 

.12 

2.16 

.05 

03 

.04 

.92 

1.43 

2.19 

1.26 

.00 

.00 

.48 

.80 

1.00 

.00 

.03 

o .  •  •  . 

1.11 

1.51 

.00 

.12 

.00 

.00 

1.51 

.85 

4.00 

.44 

.00 

.08 

.92 

•   •   ■   • 

.08 

.28 

4  ... 

1.32 

3.41 

.32 

.86 

1.00 

.45 

.42 

.88 

.00 

.16 

.52 

].83;. 

.27 

.47 

.00 

.40 

6.... 

2.72 

2.80 

1.04 

2.79 

.85 

.11 

.00 

.85 

.00 

.03 

.10 

.50 

.25 

.00 

•    .30 

6. . . . 

.89 

.00 

.22 

.10 

.04 

.21 

12 

.00 

.00 

.77 

3.14 

.41 

.59 

.02 

.00 

.12 

7.... 

.45 

.00 

.27 

.33 

.00 

.62 

2.05 

3.00 

.55 

.00 

3.43 

1.14 

1.01 

.45 

1.00 

.00 

o.  .  .  . 

.67 

1.25 

.27 

.08 

.00 

.00 

2.77 

.42 

.85 

.02 

1.80 

.29 

.67 

.00 

.45 

2.85 

V .  .  .  . 

2.07 

.40 

1.84 

.00 

.02 

.29 

.60 

8.09 

.00 

.00 

.02 

1.50 

1.17 

.00 

.00 

1.57 

10.... 

1.05 

.34 

.00 

.25 

.23 

.27 

.83 

.00 

.00 

1.68 

1.20 

1.68 

1.91 

.02 

.08 

1.36 

11 

.54 

.00 

.35 

.67 

1.20 

1.14 

.15 

.28 

.00 

.39 

1.89 

1.75 

2.08 

.80 

.01 

.48 

13. . . . 

.43 

1.16 

.00 

.17 

.06 

.«8 

.00 

1.71 

.00 

.72 

.25 

.10 

2.46 

2.45 

.06 

1.86 

18.... 

.14 

.29 

.00 

.00 

.08 

3.20 

.00 

.32 

.00 

.26 

2.35 

.34 

.49 

.10 

1.02 

.37 

14.... 

.03 

.81 

.00 

.12 

.04 

1.40 

.14 

.00 

.15 

2.46 

.76 

.15 

.46 

.04 

.55 

.00 

15. . . . 

.60 

.00 

.00 

.00 

.07 

1.18 

.00 

.00 

•     .00 

1.09 

.75 

.35 

2.50 

1.51 

.30 

.08 

16 

1.26 

.80 

.00 

1.22 

.00 

.00 

.25 

.00 

.07 

4.85 

.99 

1.32 

.45 

.05 

.00 

17.... 

.81 

.26 

.18 

OB 

.08 

.10 

.67 

.06 

.00 

.01 

8.07 

.80 

.01 

1.06 

2.19 

.00 

18.... 

1.19 

.00 

.00 

to 

.50 

.00 

.14 

.00 

.00 

.00 

.52 

.06 

2.21 

1.23 

.03 

.00 

1» 

.06 

.19 

.00 

.08 

.52 

2.42 

.00 

.42 

.02 

.04 

.00 

.19 

.87 

.00 

.05 

20... 

.29 

.27 

.00 

.08 

.00 

5.18 

.69 

.00 

.00 

.84 

.18 

.29 

.45 

.00 

.00 

21 

.06 

.07 

.40 

.00 

1.46 

.79 

.28 

.00 

.00 

.37 

.11 

.49 

.13 

.00 

.02 

22. . . . 

.18 

.24 

.38 

.78 

.00 

.26 

.00 

.00 

.10 

.31 

.22 

.19 

.00 

.00 

.00 

23.... 

.00 

.03 

.54 

.15 

.19 

.20 

.00 

.00 

.01 

1.14 

.29 

.12 

.12 

.00 

.04 

.00 

24 

.86 

.18 

2.40 

.04 

.00 

2.75 

.70 

.00 

.00 

1.12 

.91 

.02 

.56 

.38 

.25 

.00 

25. . . . 

.30 

2.50 

.78 

.08 

.00 

1.24 

.49 

.20 

.00 

1.96 

.48 

.00 

.00 

.01 

.02 

.00 

26.... 

1.52 

.82 

.32 

.83 

.00 

.09 

.60 

.20 

.00 

.05 

2.41 

.02 

.11 

.00 

.09 

.05 

27 

.36 

4.12 

.22 

.28 

.00 

.06 

.92 

.00 

.00 

.01 

•   •   •   • 

(        ) 

.00 

.23 

.08 

.00 

28.... 

.13 

1.95 

.04 

.00 

.00 

.20 

.95 

.00 

.00 

.00 

2.00 

H 

.00 

.19 

.25 

.00 

29. . . . 

.53 

•   •   •   • 

.30 

.00 

.70 

.52 

.17 

.25 

.00 

.00 

.17 

.05 

•   •   •   • 

.00 

.00 

30 

.30 

•   •   ■   • 

.04 

.00 

.12 

.00 

1.32 

.00 

.00 

.00 

.11 

1.16 

.02 

•   •   •   • 

.00 

.00 

31.... 

.03 
19.44 

•   •   •   • 

.07 

•    *    •    • 

.00 

•   •   •   • 

.00 

.13 

•    •    •    • 

.00 

•   •   •   • 

.42 

.06 

«   •  •   • 

1.36 

•   •   •   • 

Totals 

25.17 

10.16 

6.90 

9.37 

19.52 

24.63 

16.38 

7.24 

12.50 

32.85 

17.06 

28.49 

11.69 

8.83 

9.09 

MONTHLY  RAINFALL  OF  NICARAGUA,  1898. 


Station. 


Jan. 


Feb. 


Mar. 


Apr.      May.       June.       July.        Aug.       Sept.        Oct. 


Nov. 


Dec. 


Total. 


Brito  and  Tola 

.25 

.00 

.08 

.08 

11.30 

14.86 

11.43 

6.17 

16.60 

25.70 

6.01 

2.41 

94.88 

Rivas 

1.07 

.12 

.10 

.00 

16.17 

18.95 

13.65 

11.85 

18.99 

20.83 

8.19 

8.14 

108.06 

Las  Lajas  . . . 

.25 

.05 

1.34 

.28 

10.60 

18.50 

10.64 

8.44 

6.79 

16.19 

4.41 

2.26 

74.75 

Rio  Viejo 

•   •   • 

.01 

.66 

•00 

13.78 

13.45 

4.01 

11.66 

7.28 

8.99 

.61 

.17 

60.62 

Tlpitapa 

k   •  •   • 

.00 

.26 

.00 

8.56 

16.88 

6.24 

7.82 

11.25 

7.12 

.93 

.17 

59.23 

Morrito 

•   •   • 

•   •  •  • 

•   •   •  • 

.07 

8.92 

14.05 

13.84 

10.20 

• . .  • 

•   •   •   • 

•   •   •   • 

•   •   •   • 

•    •   •   • 

Ft.  San  Carlos. 

»  •   •  • 

•   •   •   • 

1.21 

3.00 

8.22 

15.56 

18.35 

8.00 

10.56 

8.93 

9.86 

5.62 

84.31 

Sabalos 

•   •   ■ 

•   •   •  • 

2.10 

6.00 

11.69 

17.13 

20.69 

11.33 

11.42 

11.81 

12.17 

10.20 

114.54 

Castillo 

•   •    • 

•   •  •  • 

■    •   •   • 

•   •   •   • 

•   •  •   • 

•   •   •   • 

18.93 

11.46 

16.22 

4.64 

14.04 

11.64 

•    •   •  • 

Machnca 

•   •   • 

•   •   •   • 

•   •   •   • 

•   •   •   • 

•   •  •   • 

•   •   •   • 

.... 

6.52 

12.86 

9.88 

15.65 

6.75 

•   •   •   • 

Rio  San  Carlos    . 

1   •   •   • 

•   •  •   • 

7.52 

11.66 

20.12 

20.79 

18.26 

11.68 

.... 

•   •   •   • 

.... 

•   •   •   • 

•   •    •   • 

Ochoa 1 

3.07 

14.08 

8.04 

12.23 

15.25 

21.47 

21.60 

12.08 

15.12 

8.02 

21.50 

8.88 

170.84 

San  Francisco*  1 

5.33 

18.43 

8.72 

11.25 

13.87 

18.87 

19.23 

13.45 

10.95 

9.09 

22.28 

10.61 

172.17 

Sarapiqnl 

»   •   •   • 

•   •  •    • 

•    •   •   • 

•   •   •   • 

•   •  •   • 

•   •  •   • 

.... 

•  •  •   • 

11.19 

11.85 

18.63 

7.12 

•   •  •   • 

Deseadot 2 

1.92 

26.98 

11.76 

8.83 

14.84 

18.66 

26.86 

13.31 

5.23 

11.92 

29.25 

21.07 

210.63 

Grey  town 1 

9.44 

25. 1 7 

10.16 

7.82 

9.37 

19.52 

24.63 

16.38 

7.24 

12.50 

32.35 

17.06 

201.64 

*  Record  incomplete  from  Jan.  1-5  incl.,  and  from  Dec.  29-31  incl.;  so  the  rainfall  at  Ochoa  for  those  days  is  added, 
t  Rainfall  not  observed  from  Dec.  25  to  31,  1898;  so  the  record  was  completed  by  including  the  corresponding  days 
of  1897. 


NICARAGUA  CANAL  COMMISSION 


MisoEu^iTEOus  Eainfall  Becokdb. 

Other  records  of  rainfall  have  been  fumiahed 
to  this  Commission  through  the  courtesy  of 
Hon.  Willis  L.  Moore,  Chief  of  the  Weather 
Burean,  as  follows: 

A  record  of  19  years  at  Eivas,  beginning  Jan- 
uary, 1880,  kept  by  Dr.  Earl  Flint,  an  American 
resident. 

A  record  at  Masaya  from  July,  18S6,  to  De- 
cember, 1896,  kept  by  ilr.  Wra,  Climie,  an 
English  Civil  Engineer.  In  January,  1897, 
these  observatiouB  were  transferred  to  Granada 


ragua  Canal  Company.     These  records  are  given 
below . 

The  greatest  fluctuation  of  Lake  Nicaragua, 
which  cannot  be  prevented,  and  which,  there- 
fore, must  be  provided  for,  ia  occaaicsied  by  the 
excess  of  evaporation,  leakage  and  use  over  the 
inflow  for  limited  periods,  hence  this  important 
factor  depends  upon  the  period  of  least  rainfall 
in  the  lake  basin.  On  tho  east  side  of  the  isth- 
mus the  problems  consist  chiefly  of  the  control 
and  discharge  of  excessive  floods,  and  of  their 
effect  upon  the  permanence  and  stability  of  the 


-  ,.T  ™.  rs"t-i ....  1  ...  1 ..~.  1  ™l,  i  .„.  I  s.rm 

TJT 

\ 

/ 

\, 

■/- 

\ 

/ 

\\ 

\ 

%N 

\    * 

— 

xA 

,'' 

u 

'"--"  ■ 

*x' 

H 

V 

' 

'"^ 

■^' 

^■; 

'"^ 

/■' 

t"\ 

Fio.  7.    Comparative  Monthly  Rainfall  at  Oreytown,  Oclioa,  Ft.  3an  Carlos  and  Tola. 


and  have  been  continued  ever  since,  although 
results  are  at  hand  only  to  the  end  of  1897. 

Records  of  rainfall  in  Granada  in  1876  by 
Ramon  Espinola,  in  1877  by  Dr.  Flint,  and  in 
1883-84  by  the  National  Institute  at  Granada. 

A  record  at  Blueflelds  by  Hon,  W.  H.  Jack- 
son and  others,  from  September,  1883,  through- 
out 1884  and  1885,  and  a  portion  of  1886. 

A  record  at  Oreytown  for  the  years  1890, 
1891,  1892,  and  a  portion  of  1893  by  the  Nica- 


works.  For  this  reason  we  are  most  concerned 
with  the  year  of  maximum  rainfall  in  this 
region.  It  is  a  somewhat  remarkable  fact  that 
the  year  1890  is  the  absolute  minimum  of  the 
Rivas  record,  and  the  ma.ximuni  in  the  Greytown 
record,  and  may,  therefore,  be  taken  as  a  typical 
illustration  of  the  problems  with  which  we  have 
to  deal.     For  this  reason  Map  1,  Sheet  3,'  has 


NICARAGUA  CANAL  COMMISSION 


MONTHLY   RAINI 


APPENDIX  3,  PLATE  XV 


RtVAS.    1880-1898. 


APPENDIX   III.— HYDROGRAPHIC   REPORT 


279 


been  prepared,  representing  as  nearly  as  may 
be  with  present  information  the  probable  distri- 
bution and  quantity  of  rainfall  in  the  year  1890 
in  southern  Xicaragua  and  northern  Costa  Kiea 
in  seven  zones.  The  first,  which  includes  the 
greater  part  of  Lake  Nicaragua  and  its  drain- 
age basin,  has  rainfall  of  less  than  30  inches, 
probably  in  some  parts  running  below  20  inches. 
The  second  zone  represents  a  rainfall  between 
30  and  60  inches.  The  next  has  a  precipitation 
ranging  between  60  and  100  inches.  The  zone 
next  further  east  represents  a  precipitation  rang- 
ing between  100  and  150  inches.  The  next  in- 
cludes that  portion  in  which  the  precipitation  is 
between  150  and  200  inches,  the  next  that  por- 
tion between  200  and  250  inches,  while  the  small 
triangular  area  about  the  mouth  of  the  San  Juan 
has  a  rainfall  exceeding  250  inches. 

The  data  upon  which  this  map  is  made  ^u^ 
the  record  of  19  years  at  Kivas,  4  years  at  Grey- 
town,  the  record  for  1898  at  other  stations  main- 
tained by  the  Nicaragua  Canal  Commission,  and 
a  few  other  records  obtained  through  the  cour- 
tesy of  Prof.  H.  Pittier,  San  Jose,  Costa  Kica, 
and  from  the  U.  S.  Weather  Bureau.  The 
record  of  Greytown  includes  the  yecirs  1890, 
1891,  1892  and  1898,  the  latter  being  the 
record  of  the  Nicaragua  Canal  Commission,  ag- 
gregated 201.64.  The  year  1890  had  a  precipi- 
tation of  296.94,  which  exceeds  that  for  1898 


by  47  per  cent  It  is  assumed  that  this  propor- 
tion between  the  rainfall  of  1898  and  1890  exists 
for  all  of  the  country  east  of  Lake  Nicaragua, 
and  47  per  cent,  was  therefore  added  to  the 
obserrations  at  each  of  the  stations  maintained 
by  the  Commission  to  obtain  the  maximum  for 
use  in  compiling  this  map.  On  the  west  side  of 
Lake  Nicaragua  and  at  Morrito,  which  is  affected 
by  similar  climatic  conditions,  the  long  record 
at  Eivas  was  taken  as  the  standard,  and  the 
rainfall  for  1890  was  obtained  by  taking  30 
per  cent,  of  the  record  for  1898,  this  being  the 
percentage  indicated  by  the  Rivas  record. 
There  is  some  indication  that  the  co-existence 
of  extreme  conditions  on  one  side,  with  the  op- 
posite extreme  on  the  other  side  is  the  rule.  The 
year  1898  is  the  year  of  minimum  precipitation 
at  Greytown,  so  far  as  our  record  of  complete 
years  goes,  while  the  record  at  Kivas  gives  for 
that  year  very  nearly  a  maximum,  being  second 
only  to  the  year  1897.  Also  the  short  record 
of  five  months  for  1893  at  Greytown  gave  a 
total  for  five  months  of  41.92,  being  much  less 
than  for  the  same  period  in  any  other  recorded 
year  at  Greytown,  indicating  that  1893  was  a 
year  of  low  precipitation  at  this  point,  while  it 
was  one  of  the  highest  in  the  Kivas  record.  Of 
course  these  zones  must  be  considered  as  only 
rough  approximations. 


MONTHLY  RAINFALL  AT  RIVAS.  NICARAGUA. 

Dr.  Earl  Flint,  Observer. 


Year. 

Jan. 

Feb. 

Mar. 

Apr. 
0.00 

May. 
10.23 

June. 

July. 

Aug. 

Sept.   • 

Oct. 

Nov. 

Dec. 
0.67 

Annual. 

1880 

0.00 

0.00 

0.00 

12.58 

3.62 

10.48 

7.95 

18.83 

5.02 

64.38 

1881 

0.00 

0.00 

0.00 

0.12 

5.20 

13.17 

8.88 

6.96 

7.42 

24.67 

10.88 

1.91 

79.21 

1883 

0.00 

0.13 

0.00 

0.00 

4.2« 

9.80 

4.04 

6.25 

7.65 

23.38 

4.20 

1.61 

61.32 

1888 

0.28  . 

0.00 

0.00 

0.14 

1.00 

8.07 

4.87 

4.34 

5.78 

18.25 

5.70 

1.34 

49.77 

1884 

0.59 

0.09 

0.00 

2.03 

2.80 

10.43 

4.98 

8.84 

• 

4.48 

15.83 

7.43 

2.24 

54.74 

1885 

0.04 

0.00 

0.00 

0.00 

1.78 

7.27 

4.81 

2.76 

5.40 

7.88 

4.36 

0.29 

34.59 

1886 

0.23 

0.20 

0.00 

0.17 

13.00 

7.87 

15.00 

20.80 

15.30 

10.40 

3.75 

0.49 

87.21 

1887 

0.90 

0.81 

0.00 

0.00 

9.17 

8.18 

4.10 

5.03 

19.42 

22.47 

2.50 

2.31 

74.89 

1888 

1.83 

0.04 

0.00 

0.00 

7.12 

8.50 

4.18 

5.00 

9.80 

16.80 

1.11 

1.13 

55.51 

1889 

0.00 

0.19 

0.07 

1.71 

11.34 

11.64 

7.48 

.  12.95 

9.80 

24.18 

3.38 

1.67 

84.36 

280 


NICARAGUA   CANAL  COMMISSION 


MONTHLY  RAINFALL  AT  RIVAS.  NICARAGUA.— Continued. 


Year. 

Jan. 

Feb. 

Mar. 

April. 

May. 

June. 
4.56 

July. 
4.73 

Aug, 
3.78 

Sept. 
2.77 

Oct. 

Nov. 

Deo. 

Annual. 

1890 

0.49 

0.11 

0.94 

0.00 

2.63 

9.68 

1.30 

0.82 

81.81 

1891 

0.00 

0.00 

0.00 

0.78 

0.75 

24.58 

4.38 

4.21 

12.42 

14.90 

2.34 

1.67 

66.08 

1892 

0.19 

0.00 

0.00 

0.00 

13.30 

9.80 

9.19 

7.48 

12.22 

21.26 

4.40 

0.43 

78.27 

1893 

0.06 

0.39 

0.00 

0.11 

20.03 

1>1.14 

13.22 

18.70 

14.00 

13.56 

2.44 

2.48 

106.13 

1894 

2.12 

0.24 

0.08 

0.00 

7.76 

6.32 

8.64 

4.57 

4.33 

14.62 

3.21 

0.43 

47.32 

1895 

0.00 

0.08 

0.19 

0.39 

8.11 

11.02 

5.25 

3.42 

8.01 

8.97 

2.04 

0.20 

47.68 

1896 

0.40 

0.08 

0.00 

T. 

3.26 

0.23 

7.43 

6.57 

7.40 

7.42 

8.62 

0.39 

47.80 

1897 

0.33 

T. 

1.04 

0.00 

21.30 

24.34 

0.41 

12.10 

17.63 

33.85 

5.15 

1.28 

123.43 

1898 

1.07 

0.12 

0.10 

0.00 

10.17 

18.95 

13.05 

11.85 

13.99 

20.83 

8.19 

3.14 

108.06 

Means 

0.45 

0.13 

0.13 

0.29 

8.38 

11.81 

0.83 

7.95 

9.78 

16.99 

4.52 

1.29 

68.55 

MONTHLY  RAINFALL  AT  MASAYA,  1886-96,  AND  GRANADA.  1897. 

Nicaragua  Observers. 


Jan. 

Feb. 

Mar. 

Apr. 

May. 

Juno. 

July. 

Aug:. 

Sept. 

Oct. 

Nov. 

Dec. 

AnnuaL 

1886. . 

»   •       •   •  •   • 

•   •   •   • 

•   •   •   « 

« 

•    •   •   • 

•    •    •    • 

8.23 

15.26 

15.34 

11.19 

0.69 

0.02 

72.70 

1887. . 

..   0.30 

0.00 

0.00 

0.00 

2.42 

10.73 

7.39 

5.74 

9.15 

23.56 

0.94 

0.99 

61.22 

1888.. 

. .   0.05 

0.14 

0.00 

0.00 

7.09 

12.09 

4.95 

9.50 

17.21 

7.67 

0.00 

0.00 

58.70 

1889. . 

. .   0.00 

0.00 

2.39 

1.18 

6.43 

17.00 

7.87 

13.43 

14.53 

13.36 

2.34 

0.25 

78.78 

1890.. 

..   0.14 

0.00 

0.00 

0.60 

1.82 

3.00 

2.86 

2.66 

2.95 

5.89 

0.42 

0.18 

20.52 

1891... 

..   0.19 

0.00 

0.00 

1.02 

0.48 

20.94 

4.52 

4.20 

10.40 

5.45 

2.78 

0.00 

49.98 

1892... 

.   0.00 

0.00 

0.00 

0.00 

7.30 

14.42 

8.70 

6.75 

9.64 

15 .  71 

1.66 

0.30 

64.54 

1893. . . 

.   0.00 

1.15 

0.00 

0.00 

9.26 

11.78 

11 .47 

15.82 

12.07 

6.51 

2.70 

1.50 

72.86 

1894.., 

..  0.32 

0.50 

0.00 

0.00 

7.87 

4.77 

3.32 

4.00 

7.49 

13.42 

1.08 

0.11 

42.88 

1885.. 

..   0.00 

0.00 

0.00 

0.41 

4.57 

4.71 

5.22 

2.90 

8.30 

14.46 

0.57 

0.06 

41.26 

1896. . . 

..   0.23 

0.00 

0.00 

0.09 

5.62 

7.90 

7.13 

2.98 

0.62 

4.22 

4.85 

0.00 

39.64 

1897. . . 

.  0.00 

0.00 

0.97 

1.77 

16.63 

30.79 

8.88 

10.87 

10.21 

11.97 

1.25 

0.28 

93.62 

Means 

..   0.11 

0.16 

0.31 

0.46 

6.32 

12.56 

6.71 

7.84 

10.38 

11.12 

1.61 

0.31 

58.06 

*  Estimated  rainfall  January  to  June,  1880,  inclusive,  is  21.97  inches. 


MONTHLY  RAINFALL. 


Year. 

Jan. 

Feb. 

Mar. 

Apr.        May. 

June.        July. 

Aug. 

Sept.            Oct. 

Nov. 

Dec. 

Annual- 

Managua. 

Lat.  12°  7^  N. 

Lonj?.  80O  16^  W. 

Elevation  148  feet. 

1891.... 

.00 

.00 

.00 

.00         1.08 

14.00         5  04 

3.04 

8.43           9.64 

7.24 

0.43 

48.90 

1892 

.00 

.00 

.00 

.00         8. .58 

11.34          6.35 
San  Antonio. 

7.9S 

9.24         20.55 

3.09 

•   •   •    • 

67.13 

Lat.  12°  32^  N. 

Long.  860  59^  W. 

Elevation  00  feet. 

1895.... 

.00 

.00 

.00 

....          ( .  \ff^ 

6.29         3.36 

5.07 

21.68         21.71 

3.42 

0.32 

69.83 

1896 

.00 

.00 

.00 

0.20       12.20 

10.50         7.54 

4.71 

13.39         11.22 

4.76 

0.98 

65.50 

1897.... 

.00 

.00 

1.26 

0.59       18.23 

14.53         6.81 
Valle  Meniek 

13.80 

10.94         31.06 

.98 

.00 

98.26 

Lat.  11°  40/  N. 

long.  850  57^^  W. 

Elevation  492  feet. 

1880 

.00 

.00 

.00 

.00       13.48 

9.92         2.24 

9.96 

6.77         13.46 

2.72 

.00 

58.55 

1881.... 

0.55 
.00 

.00 
.00 

.00 
.00 

.00         9.94 
.00          1.93 

12.88         7.52 

8.86 
6.30 

9.10         22.68 
4.92         19.13 

9.83 
2.76 

0.98 
.00 

81.84 

1882 

12.87 

47.91 

1883 

.00 

.00 

.00 

.00         1.35 

7.44         3.94 

•   •   •   « 

•    •••                        •••• 

•    •   •   • 

•   •   •   • 

•   •   •   • 

NICARAGUA  CANAL  COMMISSION 

JANUARY  PEBRUAHY 


D 

1 

r 

E. 

S 

bh 

1 

1 

1 

O 

1 

■ 

E- 

,3 

)N 

ill 

ll 

0 

I 

E/ 

3 

3N 

1 

1 

1 

1 

J 

» 

m 

IB    a    to   IS 

APPENDIX  3,  PLATE  XVI 
3U8T               SEPTCMBCn             OCTOBER              NOVEMBER            DECEMBEW 

o     «•    >-       :       1      «.<«...-      1       ,«««..-..       I       J      »■    ,i     «.     I.      1       .1     »     :i     >^    a..„| 

111 

iruii       iBso                                       1 

H 

.    I 

1 

il         J        .ljLU.^__Li 

IV 

XII 

M       esT 

I  Tl 

til 

Lih 

^ 

1, 

jUll  lI  iliUlLiJjLjjJ- 

i 

3  IS 

li,„ 

1 

1   1  I     ill  1    1 

1 

J      ll       It      ill      .        l_._luJ_._. 

JULV  AUGUST  SEPTEMBEB  OCTOBER  NOVEMBER  OECEMBEn 

AS,   1890,  1897,  1898. 


APPENDIX   III.— HYDROGRAPHIC   REPORT 


281 


MONTHLY  RAINFALL  AT  GRANADA. 


Year. 


Jan.        Feb. 


Mar. 


Apr. 


May.        June. 


Total 
July.        Auk.  Sept.        Oct.        Nov.       Dec.       Annual. 


1870 

•   • 

•  • 

•    • 

•  • 

5.77 

13.65 

26.61 

4.96 

•   • 

•   • 

•   • 

•   • 

•   • 

1877. . . . 

0.00 

0.00 

0.00 

0.00 

11.57 

10.24 

10.12 

5.33 

17.36 

5.27 

0.87 

0.59 

61.34 

1883 

0.35 

0.00 

0.00 

0.i8 

0.28 

5.20 

2.66 

5.47 

9.74 

19.91 

3.64 

0.00 

47.43 

1884 

0.00 

0.00 

0.00 

0.00 

0.00 

8.25 

3.99 

3.75 

8.82 

8.63 

2.28 

0.26 

35.98 

1876. 

Observer. 

Ramon  Espi 

nola. 

1877.... 

.  .Observer 

.Earl  Flint. 

Location,  N.  ll®  56',  W.  85°  54';  elevation,  218  ft. 
1883-1884 Observed  by  National  Institute;  elevation,  230  ft. 


• 

RAINFALL  AT  GREYTOWN,  NICARAGUA. 

« 

Jan. 

Fgb. 

Mar. 

Apr. 

May. 

June. 

July. 

Aug. 

Sept. 

Oct. 

Nov. 

Dec. 

TotaL 

1890 

26.80 

6.36 

5.93 

18.11 

4.93 

46.84 

52.55 

35.72 

8.14 

34.36 

25.55 

41.65 

296.94 

1891 

20.30 

2.57 

1.95 

10.40 

13.78 

26.95 

23.57 

19.49 

14.16 

20.21 

28.15 

32.74 

214.27 

1892 

28.57 

11.38 

4.98 

18.38 

50.88 

13.42 

38.96 

23.63 

11.47 

27.95 

36.93 

24.65 

291.20 

1893 

17.70 

7.53 

3.93 

9.99 

2.77 

*   •  •   • 

. .  • « 

•   •   •   • 

•   •   •   • 

•   •   ■   • 

•   •   •   • 

. .  *  • 

■   •  •   • 

1898 

19.44 

25.17 

10.16 

7.82» 

9.37 

19.52 

24.63 

16.38 

7.24 

12.50 

32.35 

17.06 

201.64 

RAINFALL  AT  BLUEFIELDS,  NICARAGUA. 

Jan. 

Feb. 

Mar. 

April. 

May. 

June. 

July. 

Augr. 

Sept. 

Oct. 

Nov. 

Doc. 

Total. 

1883 

•                       •   • 

•  • 

•  • 

•    . 

•   • 

•   • 

•   • 

•    • 

3.42 

8.13 

12.13 

17.00 

•   • 

1884 

10.25 

6.39 

3.21 

2.06 

2.67 

8.01 

17.06 

16.40 

5.82 

4.99 

9.71 

11.15 

97.72 

1885 

1.96 

1.60 

2.66 

2.87 

5.89 

13.37 

19.82 

11.75 

8.07 

2.69 

7.70 

3.15 

81.53 

1886 

7.28 

3.94 

1.63 

•   • 

•   • 

•   • 

•   • 

8.55 

* 

•   • 

•   • 

•   • 

•   • 

•   • 

Day 

1 

2.... 
3.... 

4 

5.... 

6 

7 

8.... 

9 

10.... 

11 

12 

13 

14 

15 


DAILY  RAINFALL  FOR  SAN  JUAN  RIVER  AT  SAN  FRANCISCO  ISLAND  FOR  1888. 

By  Maritime  Canal  Co. 


Jan 


Feb 


Mar 


Apr. 


May 


June. 


July. 

Aug. 

Sept. 

Oct. 
1.20 

Nov. 

Dec. 

2.61 

3.27 

.00 

.14 

.20 

.87 

.05 

.00 

.05 

.00 

2.15 

.17 

.53 

.00 

.10 

.00 

2.93 

.77 

1.87 

.00 

.00 

.00 

8.97 

2.77 

.43 

.34 

.17 

.35 

8.50 

.09 

.87 

.00 

.38 

.13 

.14 

.07 

1.11 

2.47 

.00 

.11 

.07 

.11 

.42 

.57 

.00 

.08 

.23 

.73 

.90 

2.30 

.00 

.03 

.05 

.68 

.00 

.00 

1.05 

.73 

.17 

1.63 

.52 

2.70 

1.27 

2.24 

.00 

.92 

.00 

2.20 

.92 

.53 

.05 

1.93 

.55 

.40 

.23 

.62 

.00 

2.42 

.13 

.00 

.07 

.73 

.00 

2.70 

.00 

.34 

1.25 

.51 

.05 

282 


NICARAGUA  CANAL  COMMISSION 


DAILY  RAINFALL  OF  SAN  JUAN  RIVER  AT  SAN  FRANCISCO  ISLAND  FOR  1888.— Continued. 


Day. 

Jan. 

Feb. 

Mar. 

Apr. 

May. 

June. 

July. 

Aug. 

Sept. 

Oct. 

Nov. 

Dec. 

16 

•    •   • 

»                       •   •   •    • 

•   •   •   • 

.«7 

.17 

1.43 

.37 

.87 

.63 

17 

•   •   • 

1                      •  •   •   1 

•   •   •   • 

.61 

1.09 

.57 

1.85 

1.94 

.00 

18 

•   •   • 

1                      •   •   •   • 

.23 

.17 

.13 

.27 

.63 

.37 

.05 

19 

•   •   •   < 

•   •   •   • 

.37 

8.07 

.73 

.31 

.69 

.28 

.77 

20 

•    m   •    * 

•   •  •   • 

.11 

1.97 

.64 

.67 

.99 

.50 

.69 

21 

•    •    •    1 

•   •   •   • 

.07 

.23 

.00 

1.27 

.26 

.10 

.00 

22 

•    •    •    1 

•   •   •   • 

.03 

.17 

.09 

.59 

1.60 

.00 

.00 

23 

•     •     •     4 

1                      •   •   •   • 

.00 

.32 

.07 

.00 

.14 

.14 

.00 

24 

*     «     •     ■ 

•   •  •   • 

.49 

1.07 

.00 

2.55 

.06 

.12 

.00 

25 

•     •     • 

t                      •   •   •   • 

.H7 

1.12 

2.07 

.00 

.16 

.28 

.00 

26 

•     •     •     • 

•   •   •   • 

.21 

1.74 

.77 

.00 

.04 

.04 

.00 

27 

•     •     •     1 

■   •  •  • 

4.51 

.47 

.00 

2.09 

.05 

.00 

.02 

28 

•     •     •     • 

•   •  •   • 

.27 

.79 

..53 

.00 

.80 

.00 

1.10 

29 

•     •     •     • 

•   •   •   • 

.61 

.17 

1.22 

.24 

.76 

.00 

1.53 

30 

■ 

•      •     •     • 

•   •   •   • 

.21 

2.47 

.52 

1.20 

.41 

.18 

.55 

81 

•     •     •     t 

•    •   •   • 

•   •   •   • 

.73 

.73 

•   •   •   • 

.36 

•   •   •   • 

.64 

32.06 

7.31 

7.94 

10.97 

16.19 

16.81 

.34.44 

19.41 

22.51 

15.86 

11.02 

20.08 

Total  for  year,  214.60  Inches. 


PRECIPITATION  AT  SAN  JOSE,  COSTA  RICA. 
Latitude,  9°  56'  N.    Longitude,  84°  8'  W.    Elevation,  3750  feet. 


Year. 

Jan. 

Feb. 

Mar. 

Apr. 

May. 

June. 

July. 

Aug. 

Sept. 

Oct. 

Nov. 

Dec. 

AnnuaL 

1866 

1.30 

0.28 

0.00 

1.14 

5.47 

4.84 

12.60 

6.14 

10.79 

9.84 

6.73 

4.80 

63.93 

1867.... 

3.86 

2.21 

0.88 

3.86 

8.23 

8.11 

8.43 

-    7.48 

12.36 

8.89 

9.61 

0.66 

73.47 

1868 

0.00 

0.00 

7.13 

0.01 

2.27 

6.91 

4.02 

5.12 

8.82 

15.47 

6.67 

0.67 

56.09 

1869 

0.28 

0.00 

0.28 

1.10 

7.95 

8.58 

6.91 

6.20 

16.47 

11.06 

3.07 

4.02 

63.93 

1870. . . . 

0.04 

0.24 

1.22 

0.67 

13.11 

10.87 

9.45 

11.18 

9.45 

10.82 

7.24 

1.80 

75.09 

1871.... 

1.10 

0.12 

0.32 

0..51 

11.42 

7.99 

14.38 

12.09 

9.66 

13.11 

4.49 

0.43 

75.56 

1872 

0.12 

0.12 

0.59 

1.97 

9.61 

10.04 

7.56 

14. 8S 

15.63 

19.84 

5.59 

0.83 

86.78 

1878 

2.52 

0.00 

0.12 

2.80 

2.. 52 

8.07 

6.71 

8.35 

15.i^t 

10.32 

4.76 

0.43 

56.84 

1874 

1.81 

0.04 

0.79 

2.36 

13.23 

6.57 

6.88 

7.18 

12.66 

7.. 52 

1.65 

0.79 

60.83 

1875 

0.00 

0.00 

0.00 

1.10 

9.92 

7.09 

8.06 

11.57 

10.98 

13.35 

0.83 

1.26 

69.76 

1876..    . 

0.55 

0.00 

0.43 

0.24 

9.72 

9.33 

6.02 

7.56 

8.11 

4.61 

2.76 

1.10 

60.48 

1877 

0.55 

0.00 

0.00 

0.00 

9.45 

6.57 

8.78 

6.26 

10.20 

8.74 

4.76 

8.11 

53. 4d 

1878 

0.00 

0.00 

1.50 

1.97 

3.59 

7.86 

8.07 

5.87 

12.99 

9.37 

8.78 

0.79 

60.29 

1879. . . . 

0.51 

0.00 

1.77 

7. .56 

8.66 

12.99 

18  11 

11.14 

13.82 

9.09 

2.40 

0.32 

86.37 

1880 

0.32 

0.00 

0.00 

0.59 

10.00 

8.27 

4.09 

17.17 

6. .50 

10.94 

3.62 

0.00 

61.50 

1884 

0.00 

0.00 

0.08 

0.32 

0.48 

2.44 

0.59 

0.67 

4.41 

1.89 

7.44 

1.22 

19.49 

1885.... 

0.00 

0.00 

0.00 

1.85 

5.98 

3.07 

7.84 

3.86 

16.59 

12.87 

16.22 

2.82 

69.60 

1886 

0.00 

0.00 

2.05 

8.98 

15.. 55 

16.85 

20.. 59 

19.61 

22.91 

28.67 

16.81 

2.28 

154.30 

1887. . . . 

0.00 

0.00 

0.67 

0.28 

9.96 

14.16 

5.61 

9.40 

11.24 

13.16 

4.93 

2.07 

71.48 

1888 

0.63 

0.71 

0.00 

0.55 

7.07 

10.24 

6.49 

6. .54 

15.71 

10.39 

2.01 

0.87 

59.21 

1889 

0.01 

0.08 

2.91 

2.41 

14.57 

8.08 

6.06 

10.76 

16.89 

20.48 

2.45 

0  48 

85.18 

1890. . . . 

0.87 

0.08 

0.75 

2.52 

10.08 

11.65 

15.67 

10.65 

8.36 

7.99 

2.56 

0.71 

71.78 

1891.... 

0.03 

0.01 

0.05 

0.74 

4.26 

7.74 

8.00 

9.84 

12.80 

15.48 

5.57 

1.16 

65.18 

1892 

0.00 

0.00 

0.13 

0.07 

12.17 

15.06 

8.70 

13.75 

14.84 

21.36 

5.03 

0.44 

91.55 

1893 

0.04 

0.00 

0.02 

0.47 

8.73 

15.28 

13.90 

13.76 

20.75 

14.93 

7.08 

2.94 

97.90 

1894 

0.04 

0.00 

0.00 

0.99 

8.00 

7.83 

3.90 

9.76 

12.80 

8.54 

6.82 

0,65 

58.28 

1895. . . . 

0.15 

0.35 

0.04 

0.86 

15.12 

12.36 

4.76 

9 .  92 

11. .50 

7.32 

8.35 

6.02 

76.75 

1896 

2 .  13 

0.00 

0.04 

5.20 

6.57 

6.50 

8.23 

4.88 

8.15 

7.«7 

12.16 

3.03 

64.76 

1897.... 

0.20 

0.00 

0.28 

1.54 

12.20 

8.98 

4.83 

15.75 

12.05 

14.92 

3.11 

1.61 

74.97 

1898 

0.35 

0.00 

0.28 

1.80 

8. .58 

15.59 

8.90 

18.39 

13.62 

11.69 

4.65 

0.08 

78.48 

APPENDIX  III.— HTDROORAPHK  REPORT 


Purl  Limw 

Matima  .. 

Turrialha 

Juli 

Jma  r«fl<M.. 
CaTlago., 
Agtmcalim 
Trea  Rios 
La  Verb«t 
Shu  Joif . 
SaaFranclKo 

Haredli 

La  Palms  uu 
the  divide. 


RAINFALL  IN  COSTA  RICA. 
N.  B.— The  stations  in  Italic  are  on  the  Caribbean  side  of  the  main  cordlllera. 


1=00' 21" 
I"  05'  3B" 
I"  13'  38" 
1°  B5'  00" 


±    II"  a! 

±    B°5' 


* 

Srt 

fl 

•f 

B 

K 

Ml 

«'l,. 

41) 

2H4 

JlfW 

aa 

1,MK4 

1^ 

asH 

sai 

1U4 

1.554 

AitA 

:^SS 

■JSrt 

flSfl 

8,433 

sail 

341 

S88 

ISO 

74.18 
61. 1» 

34.77 


EVAPOKATIOS. 

The  rate  of  evaporation  in  the  region  of  Lake 
Nicaragua  has  an  important  bearing  upon  the 
practicability  of  maintaining  the  summit  level 
of  the  canal  imder  any  plan  yet  proposed,  and 
upon  the  means  that  must  be  provided  for  the 
maintenance  of  suoli  level. 

Observations  have  shown  that  the  inflow  to 
Lake  Nicaragua  during  the  dry  season  is  very 
small  and  indicate  that  in  some  years  it  is  prac- 
tically zero  for  a  considerable  period,  during  the 
dry  season,  while  at  the  same  time,  evaporation  is 
at  its  maximum.  For  the  purpose  of  ascertain- 
ing the  amount  of  this  evaporation,  observations 
were  taken  at  Fort  San  Carlos,  San  Ubaldo  and 
Las  Lajas.  For  this  purpose  evaporation  pans 
were  provided,  which  were  made  of  galvanized 
sheet-iron  about  three  feet  square  and  two  feet 
deep.  The  pan  was  anchored  in  some  protected 
body  of  water,  filled  nearly  full  and  floated  by 
means  of  wooden  buoys,  fastened  to  the  sides, 
A  scale  was  provided  reading  to  five-hundredtha 


of  an  inch,  and  by  estimation  to  single  hun- 
dredths. On  this  the  height  of  the  water  was 
read  each  day,  which  was  compared  with  the 
reading  at  the  same  hour  on  the  previous  day. 
The  rainfall  was  measured  by  means  of  a  rain 
gage,  located  in  the  immediate  vicinity  and  its 
result  applied  as  a  correction  to  the  change  of 
water  elevation  in  the  pan. 

The  obstacles  to  continuous,  reliable  observa- 
tions of  evaporation  are  many.  The  pan  was 
sometimes  driven  aground  by  winds  and  storms 
and  the  water  spilled.  Sometimes  a  leak  would 
be  caused  in  this  way.  Other  causes  tended  oc- 
casionally to  vitiate  results,  an  idea  of  which 
may  be  formed  from  the  following  notes  taken 
from  the  observer's  note-book: 

"  Heavy  sea  filled  the  pan. 

"  Evaporating  pan  blown  on  the  beach  with 
bottom  broken. 

"  Soap  found  in  pan ;  some  one  had  been  tak- 
ing a  bath. 

"  Sand  cleaned  out  of  pan. 


284 


NICARAGUA  CANAL  COMMISSION 


"  Pan  swamped. 

"  Pan  shelved. 

"  Reading  useless  on  account  of  waves  break- 
ing into  pan." 

At  Las  Lajas  the  pan  was  disturbed  at  first 
by  cattle.  This  was  remedied  by  anchoring  it 
in  water  too  deep  for  them.  At  San  Carlos  the 
pan  became  at  times  a  favorite  roost  for  birds 
and  a  scarecrow  had  to  be  provided  to  keep  them 
away.  However,  it  was  usually  possible  to 
judge  correctly  as  to  whether  the  observations 
had  been  vitiated  and  care  was  taken  to  eliminate 
those  with  regard  to  which  a  reasonable  doubt 
existed.  As  might  be  expected  from  the  above, 
there  are  many  breaks  in  the  continuity  of  ob- 
servations, days  being  omitted  on  account  of 
doubtful  conditions. 

In  the  following  tables  the  daily  mean  in  each 
case  represent*  the  mean  of  good  observations, 
this  being  multiplied  by  the  number  of  days  in 
the  month  to  obtain  the  total  for  the  month. 

As  there  was  usually  some  motion  to  the  water 
in  the  pan  it  was  not  always  practicable  to  read  ' 
the  scale  correctly  within  a  tenth  of  an  inch,  but 
whatever  error  occurs  from  this  cause  applies 
with  opposite  sign  to  results  preceding  and  fol- 
lowing the  observation  and  the  error  is  thus 
eliminated.  The  seeming  fluctuation,  therefore, 
which  might  be  inferred  from  the  table  of  ob- 
servations is  chiefly  due  to  this  cause  and  in  the 
main  is  unavoidable,  and  in  anv  event  does  not 
affect  results,  except  in  a  slight  degree  at  the 
beginning  and  end  of  a  series  of  continuous  ob- 
serv^ations. 

Allowance  must  be  made  in  the  use  of  these 
results  for  the  fact  that  the  conditions  obtaining 
on  the  lake  cannot  be  duplicated  in  the  evaporat- 
ing pan.  During  the  dry  season  the  trade  winds 
blow  stronfflv  from  the  eastern  side  of  the  lake 
to  the  western.     Except  along  the  eastern  shore 


the  surface  of  the  lake  is  blown  into  billows,  the 
waves  often  attaining  a  considerable  height  and 
being  crowned  with  whitecaps.  In  this  way  a 
large  quantity  of  spray  is  thrown  into  the  air, 
and  the  total  water  surface  in  contact  with  the 
trade  wind  is  much  greater  than  the  level  sur- 
face of  the  lake.  More  than  half  the  area  of  the 
lake^  therefore,  must  lose  by  evaporation  a 
greater  depth  of  water  than  the  pan. 

The  observations  taken  furnish  another 
method  of  computing  the  evaporation. from  the 
lake. 

Records  showing  the  height  of  the  surface  of 
the  lake  were  kept  at  San  Carlos,  San  Ubaldo 
and  Las  Lajas.  Observations  of  rainfall  were 
taken  at  all  these  places,  and  at  Tipitapa,  about 
ten  miles  northwest  of  the  lake.  A  circuit  of 
the  lake  was  made  in  April  and  May,  for  the 
purpose  of  measuring  the  inflowing  streams. 
A  record  of  the  discharge  of  San  Juan  river  was 
kept  at  Sabalos,  above  Toro  rapids.  From  April 
10  to  May  10  the  lake  fell  8.64  inches.  During 
the  same  time  rain  fell  as  follows: 

Inchefi. 

San  Carlos 3.20 

Las  Lajas 22 

San  Ubaldo 50 

Tipitapa ; 00 

Sum 3.92 

iiean    98 

The  measured  outflow  was  714,000  acre-feet, 
and  the  inflow  is  estimated  to  have  been  120,- 
000  acre-feet,  making  a  net  decrease  of  3.50 
inches  in  lake  elevation,  due  to  flowage. 

Assembling  these  facts,  we  have 

Evaporation  =  8.64  -f  .98  —  3.50  =  6.12. 

During  the  same  time  the  evaporation  ob- 
served was  as  follows: 


APPENDIX  III.— HYDROGRAPHIC   REPORT 


285 


Inches. 

San  Carlos 4.77 

Tipitapa 6.05 

San  Ubaldo 6.30 

Las  Lajas 7.89 

Sum 25.01 

Mean 6.25 

This  is  a  cloee  check,  and  indicates  that  either 
method  would  afford  a  fair  approximation  of 
the  amount  of  the  evaporation.  Being  the  last 
month  of  the  dry  season,  it  probably  represents 
about  the  maximum  for  the  year.     The  rain- 


fall records  for  Eivas  and  also  for  Masaya  show 
that  1897  was  the  year  of  maximum  rainfall  so 
far  as  observed,  and  1898,  appears  to  be  above 
the  average,  so  that  during  the  season  under 
consideration  the  evaporation  was  probably  not 
as  great  as  it  sometimes  becomes,  and  in  the 
dryest  years  may  approach  seven  inches  in  one 
month. 

The  usual  dry  season  at  Rivas  is  from  about 
the  middle  of  December  to  the  middle  of  May. 
It  doubtless  begins  earlier  and  ends  later  in  the 
years  of  least  rainfall,  and  may  continue  over 
six  months. 


EVAPORATION,  LAS  LAJAS.  NICARAGUA. 


Day. 


lovD. 

Mar. 


Apr. 


May. 


June.        July.        Aug, 


Sept. 


Oct. 


Nov. 


Dec. 


1809. 
Jan. 


Feb. 


Mar. 


1 
3. 

3. 
4. 
6. 

6 

7, 

8. 

9. 

10. 

11. 
12. 
13. 
14. 
15. 

16. 
17. 
18. 
19. 
SO. 

21. 
32. 
23. 
24. 
25. 


.10 
.20 
.07 
.18 


.30 
.31 
.84 

.28 
.28 

.21 
.24 
.35 
.31 
.27 

.23 
.33 
.30 
.24 


.17 
.24 
.21 

.28 
.26 

.27 
.28 
.39 
.23 
.20 


.24 
.26 
.24 
.27 


.27 
.23 
.27 
.32 
.29 

.24 

•   •   ■   • 

.21 
.28 
.10 

.19 
.25 
.16 
.16 
.04 

.13 


.14 
.20 

.13 
.22 
.20 
.21 
.19 

.14 
.24 

.17 


.04 


.15 
.07 
.17 
.10 
.07 

.18 

•  •   • 

.12 
.01 
.05 


04 
17 


19 
14 

17 
18 


19 
12 
09 
13 

06 
03 


11 


07 


07 


.12 
.13 


.06 
.11 
.08 
.09 

.05 
.18 
.12 
.14 
.11 

.09 
.11 
.16 
.08 
.13 


.15 
.08 
.10 


.10 
.11 
.09 

•  •   • 

.10 

.10 
.13 
.08 
,15 
.16 

.11 
.15 

•  •   • 

.02 
.10 

.10 
.11 
.04 
.09 
.11 

.04 
.11 

•  •   • 

.04 
.08 


05 

•   • 

06 


16 

•    • 

05 

07 
05 
10 
05 


14 
16 
13 
05 

13 
04 


.10 
.10 
.15 


.10 
.10 
.22 
.12 
.05 


.08 
.03 


I 


.09 
.03 

.04 
.10 

.45 


.10 
.02 
.07 
.07 
.10 

.11 
.10 
.09 
.05 
.14 


.09 
.07 
.08 
.09 
.11 

.04 
.15 
.10 
.14 
.13 


1 


.30 

.12 
.15 

.09 
.12 
.12 
.08 
.09 


.12 
.13 
.10 
.10 
.10 

.12 
.07 
.11 


.09 
.14 
.07 
.11 


.10 

.22 
.13 


{.88       { 


.82 


.12 
.80 
.10 
.20 
.08 

.09 
.09 
.11 


.10 
.12 
.18 
.18 


.20 

.25 

.28 
.12 


08 

.13          1 

•  VA^ 

.10 

11 

.08 

« 

.15 

12 

.11 

.12 

.10 

10 

.10 

.18 

.17 

10 

.10 

.11 

.08 

1- 


.11 

.14 

80 
.15 

.07 
.11 


.17 


1 .27         I  .22        I  • 


28 


286 


NICARAGUA   CANAL  COMMISSION 


EVAPORATION,  LAS  LAJAS,  NICARAGUA.— Continued. 


Day. 

26 

27 

28 

29 

30 

31 

Mean . . « 

Total . . . 


Mar. 
18JW. 


Apr.         May.        June.       July.        Aug. 


Sept. 


Oct. 


Nov. 


1-PGC» 


Jan. 

lollv. 


Feb. 


Mar. 


.18 
.22 
.32 
.15 

•   •   • 

.25 


.34 
.28 
.26 
.25 
.22 


.03 
.13 
.10 
.12 


•    •   •    • 


.14 


03 

.10 

.05 

05 

.12 

•   •   •   • 

11 

.16 

.02 

12 

•   *   •   • 

.10 

■   • 

•   •   •   • 

.08 

.05 


.10 
.10 
.07 


.15 

*   •   • 

.07 
.06 
.06 


.12 
.13 
.09 
.06 
.11 
.12 


.08 
.09 
.12 
.12 
.16 
.12 


11 
15 
11 


.33 
.04 
.05 
.17 
.13 
.13 


.186 


.271         .193 


.145 


.109 


.110 


091 


.088      0.100 


.097 


.110 


121 


.137 


5.77        8.13 


5.98 


4.35 


3.38 


3.41 


♦> 


73 


2.73 


3.00 


3.01 


3.40 


39 


4.25 


EVAPORATION,  SAN  UBALDO  AND  MORRITO,  NICARAGUA,  1898. 


Day. 


April. 


May. 


June. 


July. 


AuRTUSt. 


September. 


1. 
2. 
3. 
4. 
5. 

6. 
7. 
8. 
9. 
10. 


11... 
12... 
13... 
14... 
15.  .. 

16... 
17... 
18... 
19... 
20... 

21 . . . 
22... 
23... 
24... 
25... 

26... 
27. . . 
28... 
29... 
80... 
31... 

Mean. 
Total 


.22 

.15 

.30 

.20 

.19 

.17 

.23 

.'22 

.14 

.32 

.25 

.20 

.13 

.15 

.20 

.20 

.30 

.25 

.25 

.10 

.06 

.30 

.19 

.12 

.20 

.15 

.16 

.25 

•  •  •  • 

.30 

•  •  •  • 

.15 

•   •  •  • 

.20 

•  •  •  • 

.18 

•  ■   •   • 

.27 

•   •  •  • 

.25 

•   •  •   • 

.26 

•   •  •   • 

.25 

.30 

.25 

.25 

.17 

.31 

.18 

.03 

.20 
.05 
.09 
.02 

.25 

•   •   • 

.17 
.32 
.36 

.08 
.21 
.13 
.14 
.20 

.20 
.15 
.18 
.23 

.15 


.22 

.17 
.26 

.13 
.28 
.02 
.20 
.14 


.214 
6.42 


.202 
6.26 


•   •   •  • 


.173 
5.19 


.10 
.12 
.21 
.15 
.15 

.13 
.10 
.11 
.11 

.12 


.25 
.35 
.21 
.21 

.12 


.21 

.17 
.05 
.15 
.28 


.05 
.27 


•  •  •  • 


.15 
.01 
.13 
.25 
.12 

.18 
.19 
.15 
.12 
.22 

.14 
.22 
.15 


.164 
.5.08 


.08 
.15 
.10 
.14 
.31 

.22 

.17 
.09 
.20 
.08 

.14 
.17 
.17 
.12 
.20 
.18 
.1.57 

4.87 


07 
12 
19 
28 
07 

18 
15 
11 
10 
23 


145 
35~ 


APPENDIX   III.— HYDROGRAPHIC   REPORT 


287 


EVAPORATION,  FORT  SAN  CARLOS,  NICARAGUA. 


Day. 

Mar. 

1808. 

Apr. 

May. 

June 

July. 

Aug. 

Sept. 

Oct. 

Nov. 

Dec. 

im          Feb. 

Mar. 

Apr. 

1... 

•             •    •    •    • 

.15 

a    a    a    • 

.11 

.19 

.06 

.22 

.20 

.14 

a    a    a    • 

•    m    •    • 

.15 

.11 

.15 

o 

A^  .     .     . 

•             •    •    •    • 

.20 

.21 

.18 

.23 

•09 

.13 

a    a    a    a 

.20 

.12 

.15 

.15 

.15 

.15 

(5 .  .  • 

•             •    •    •    • 

.16 

.16 

.18 

.13 

.11 

.14 

.06 

.15 

.12 

•    m    •    * 

.10 

.11 

a     a     a     a 

4... 

•             •    •    •    • 

.19 

.16 

.18 

.05 

.10 

a    a    a    a 

.13 

.20 

.15 

a    •     a    a 

.15 

.15 

a     •    a    • 

5. . . 

•               •    •    •    a 

.09 

.08 

.12 

.10 

.09 

.07 

a    a    a    a 

.10 

.19 

.12 

.15 

.10 

.17 

6. . . 

•               •    •    a    • 

.01 

.20 

.10 

a    a    a    a 

.14 

.07 

a    a    a    a 

.10 

.11 

.15 

.14 

.12 

.12 

7... 

•               •     •    •    ■ 

•  •   • 

.18 

.07 

.14 

.14 

.09 

m    •    •    • 

.15 

.18 

.13 

10 

a    a    a    a 

a    a    a    a 

o.  .  . 

•               •    •    •    a 

.17 

.15 

.21 

.12 

.18 

.06 

a    a    *    • 

•    •    •    a^ 

.14 

.10 

a    a 

a    a    a    • 

a     a     a     a 

«».  .  • 

.12 

.19 

.22 

.11 

.10 

.11 

.06 

.11 

.07 

.14 

.08 

a    a 

•    a    a    a 

.14 

10... 

.01 

.13 

•     •    •    a 

.20 

.11 

... 

.18 

.12 

.08 

a    a    a    a 

.08 

.10 

•    a    a 

a     a    a    a 

11... 

•               •    •    •    a 

.16 

■    a    a    a 

.10 

>    a    a    a 

.11 

.20 

a    a    a    a 

.12 

.15 

.10 

a    a 

a    a    a    a 

.10 

1*> 

X  w  .    .   . 

.12 

.18 

•    •    •    • 

.11 

•    a    a    a 

.11 

•      9      •      • 

.13 

|.25 

.12 

.08 

11 

.14 

a    •    a    a 

13... 

.08 

.12 

a    •    •    • 

.16 

.18 

.11 

a    a    •    a 

.14 

a     a    a    a 

a    a    a    a 

.08 

.15 

.15 

14... 

.17 

.13 

■    •    •    • 

.29 

.09 

.12 

m    •    •    • 

.10 

.09 

.15 

^a    a    a    a                            ■ 

15 

.10 

.10 

15... 

.06 

.17 

a    a    •    • 

.07 

.15 

.06 

•    m    •    • 

.09 

.05 

.15 

a    a    a    a 

.13 

.10 

.15 

16... 

.19 

.26 

•     •    •    • 

.09 

.13 

.10 

.12 

.15 

a    a    a    • 

.11 

.10 

06 

.10 

.15 

17... 

.15 

.09 

a    •    a    a 

•   •   a   • 

.12 

.12 

.22 

a    a    a    • 

a    a    a    a 

.14 

.10 

.07 

.15 

.20 

18... 

.21 

.15 

.05 

.12 

.12 

.19 

.17 

a    a    a    a 

.06 

.12 

.11 

08 

.15 

.15 

19... 

.19 

.08 

•    •    •    a 

a    •    •    • 

.31 

.21 

.04 

a    a    a    a 

.10 

.15 

.15 

12 

.15 

.20 

20... 

.20 

.18 

.22 

a    a    a 

.07 

.14 

.09 

.11 

.10 

.10 

.10 

10 

.15 

.20 

21... 

.20 

.22 

•    •   •   • 

•    %    m    9 

a    a    a 

.12 

.08 

a    a    a    a 

.13 

.05 

.22 

10 

.15 

.20 

22... 

•              •    •    •    a 

.11 

a     •    a    a 

•    %    •    % 

.12 

.14 

.05 

.19 

•   •   *   • 

.15 

.18 

.15 

.15 

•     .20 

23... 

.14 

.16 

a    •    •    • 

.17 

a    a    a 

.13. 

.06 

•    •    a    • 

.15 

.10 

.15 

15 

.15 

.20 

24... 

.22 

.15 

a    a    a    • 

a    •    a 

•    •    • 

.07 

.15 

a     •    a    • 

|.15 

1  .20 

.15 

•    a 

.15 

.15 

25... 

.14 

.17 

a    a    a    • 

.12 

.10 

.00 

.15 

.14 

.10 

a    a 

.20 

.15 

26... 

.28 

.11  > 

m    •    •    • 

.11 

.12 

.11 

a    a    a    a 

•    m    •    • 

.10 

.17 

.10 

10 

.15 

.20 

<S  1  .  .  . 

.12 

.16 

m    •    •    • 

.25 

.08 

.11 

.10 

a    a    a    a 

.08 

.09 

.10 

10 

.15 

.15 

28... 

.15 

.18 

.07 

.12 

.05 

.14 

.15 

•    a    • 

.08 

.18 

.10 

15 

.15 

.20 

21> .  . . 

.21 

.16 

.12 

.12 

.07 

.17 

a    •    •    • 

.15 

.18 

.09 

.10 

•    a 

.15 

.20 

30... 

•               •    •    a    • 

.15 

.12 

.07 

.11 

.11 

a    a    •    a 

.15 

m    %    *    • 

.06 

.15 

•    • 

.20 

.25 

31... 

•               •    •    a    • 

•   •    •   • 

.12 

a     a     •     • 

.10 

.09 

•    a    a    a 

.15 

a 

•      9     •     • 

0 

.09 

•    a    a    a                        a    a 

a    a 

.10 

a    a    a    a 

Mean 

.       .153 

.164 

.147 

.140 

.124 

.119 

.118 

.132 

.113 

.130 

.121         .1 

17 

.140 

.168 

Total! 

s      4.74 

4.92 

4.56 

4.20 

3.84 

3.69 

3.54 

4.09 

3.39 

4.03 

3.75         3. 

28 

4.34 

5.04 

ESTIMATED  MONTHLY  EVAPORATION  OF  LAKE  NICARAGUA. 

Mod 

th. 

Discharge  in  Second-Feet. 

. ^ Total  for 

San               Tias             Ft.  San       month. 
Ubaldo.        Lajas.          Carlos. 

Month. 

Discharge  in  Second-F 

San                 Ta8           Ft 
Ubaldo.          LaJas           Ci 

eet. 

,  San 
irlos. 

Total  for 
month. 

18 

98. 

Inches. 

Inches. 

Inches. 

Mean. 

1898. 

Inches. 

Inches.         In 

ches. 

Mean. 

Marcl 

I      a    •    •    • 

•    •    a    • 

5.77 

4. 

74 

5. 

25 

( 

Dctober . . 

a                          a 

»    •    a 

2.73             4 

.09 

8. 

41 

April 

6.42 

8.13 

4. 

92 

6 

.49 

November 

■                          a    a 

a    « 

3.00             8 

.39 

3. 

20 

May  . 

6.26 

5.98 

4. 

56 

5 

.60 

December 

*                           • 

»    •    a 

3.01             4 

.03 

3. 

52 

June. 

5.19 

4.85 

4. 

20 

4 

.58 

1899. 

July  . 

5.08 

8.38 

8. 

84 

4 

.10 

« 

January. . 

•                          •     I 

•     ■ 

3.40             3 

.75 

3. 

57 

An^ 

Bt  .  .  . 

4.87 

3.41 

8. 

69 

3 

.99 

] 

February. 

•                          a 

»    a    a 

3.39             3 

.28 

3. 

34 

Septei 

mber. 

•    •    •    a 

2.73 

3. 

54 

3 

.13 

■ 

March  . . . 

a                        a    1 

•    a 

4.25             4 

.34 

4. 

30 

NICARAGUA  CANAL  COMMISSION 


EVAPORATION,  TIPITAPA.  NICARAGUA. 


17 
30 

06 

30 

IS 

OH 

u«» 

300 

-88               OS            IM            ISO             44            143              36            ISB 

184 

84 

147 

Toul 

5  77 

7  IB          5.7B          AM          S.40          4A6          4.43           8.87          4.22 

iM 

4.  S 

4..5<l 

EVAPORATION,  SAN  CARLOS  RIVBR,   NICARAGUA,  1898. 

APPENDIX   III.— HYDROGRAPHIC   REPORT 


289 


EVAPORATION,  SAN  CARLOS  RIVER,  NICARAGUA,  1898.— Continued. 


Day. 


March. 


April. 


May. 


Juno. 


11 

.02 

•   •   ■                                                                              • 

•    ■   • 

•    •    • 

• 

12 

.06 

06 

•    • 

.10 

18 

.05 
.04 

10 
11 

.21 
08 

•   •   •   • 

14 

»   •   «   • 

15 

•   ■   ■                                                                             1 

OS 

I  •   • 

.15 

16 

08 
.10 

>   •   • 

.10 

•   «  •   • 

17 

18 

•   •   •                                                                         •  1 

•   •                                                                                        < 

09 

19 

.10 

I   •   • 

20 

07 

.11 

21 

.12 

.12 

22 

.04 

.13 

23 

•   •    ■                                                                           • 

»  •  ■                                                                                  t 

03 

•      •       •                                                                                                                                                           •      4 

»   •   • 

.09 
06 

.10 
.10 

.07 

25 

27 

•      •      ■                                                                                                                                                              • 

>  •  • 

.07 

•      •      •                                                                                                                                                              • 

>  • .                                       • 

»   •   • 

29   

.08 

>  • .                                       • 

•   •   • 

.13 

.10 

■   •   • 

31 

•   ■   •                                                                          • 

»   •   •                                                                              • 

»   •   • 

Mean 

.077 

090 

095 

.093 

Total 2 

.39                                    2 

.70                                      2 

.95 

2.7 

9 

EVAPORATION,  OCHOA.  NICARAGUA. 


Day. 

Mar. 
1898. 

Apr. 

May. 

Juno. 

July. 

Aug. 

Sopt 

Oc-t. 

Nov. 

Dec. 

Jan. 
1899. 

Feb. 

1.... 

•    •   •    • 

.04 

.10 

.03 

.08 

.08 

.11 

.10 

.05 

.05 

•    •    •    • 

.12 

2.... 

•    •   •   • 

.03 

.07 

.10 

.06 

.02 

.06 

.09 

.05 

.04 

•    •    ■    • 

.05 

3. . . . 

>                                •   •    ■    • 

.11 

.14 

.10 

•   •  •   • 

.06 

.04 

.07 

.05 

.08 

.10 

.10 

4.... 

.08 

•   •   ■   • 

.20 

.08 

.02 

.01 

.07 

.05 

.07 

.08 

.10 

.07 

5.... 

.17 

.25 

.11 

.07 

.11 

.11 

.04 

.09 

.08 

.03 

.06 

•    •   •   • 

«.... 

.14 

.02 

.04 

.10 

»    .03 

.01 

.03 

.11   • 

.12 

.09 

.08 

.08 

pa. 
< 

.18 

.09 

.20 

.09 

.06 

.03 

.01 

.04 

.09 

.06 

.05 

8... 

.18 

.09 

.16 

.07 

.03 

.09 

.11 

■   •   •    • 

.06 

.09 

.08 

9... 

.15 

.11 

.13 

.11 

.11 

.03 

.05 

.03 

.04 

.04 

.10 

10... 

.09 

.19 

•   •   •   • 

.05 

.04 

•    ■    • 

.07 

•   •  •  • 

.06 

.14 

.05 

11... 

.03 

.04 

.00 

.06 

.02 

.06 

.05 

•   •    •   • 

.08 

.06 

.07 

12... 

.05 

.11 

.12 

.16 

.06 

•   •   • 

.08 

.OS 

.06 

.04 

.04 

13... 

.20 

.11 

.07 

.06 

.11 

.10 

.04 

.11 

.06 

.OS 

■    •   •   • 

14... 

»                             •   •   ■   • 

.12 

.08 

.09 

.11 

.08 

.05 

.04 

.02 

.02 

.08 

15... 

.27 

.12 

.08 

.05 

.05 

.08 

.08 

.08 

.07 

.06 

16... 

>                             •   •   •   • 

.11 

.08 

.02 

.07 

.07 

.06 

.07 

.12 

.08 

17... 

•   •   •   • 

.10 

.09 

.05 

....    ^ 

.05 

.08 

.02 

.09 

.00 

.02 

18... 

.14 

.13 

.11 

•   •   •   • 

.04 

.05 

.00 

.03 

•    •    •    • 

.06 

19... 

.26 

.08 

.21 

.15 

.06 

.08 

.12 

.08 

.02 

.11 

30... 

.15 

.18 

.09 

.17 

•   •  •   • 

.04 

.03 

.08 

.08 

.05 

.07 

19 


290 


NICARAGUA   CANAL  COMMISSION 


EVAPORATION,  OCHOA,  NICARAGUA.— Continued. 


Day. 


Mar. 

1898. 


Apr. 


May. 


June. 


July 


Au^. 


Sept. 


Oct 


Nov 


Dec. 


Jan. 


Feb. 


21... 

.04 

.13 

•   •   •  • 

.09 

.12 

.02 

.07 

.06 

.04 

.03 

22... 

.10 

.10 

.04 

.08 

.15 

.09 

.03 

.07 

.09 

•   •   •   • 

23... 

.12 

.06 

.02 

.07 

.03 

.09 

.04 

.09 

.05 

.08 

24... 

.10 

.11 

•   •   •   • 

.28 

.06 

.15 

.05 

.07 

.08 

.07 

25... 

.06 

.11 

•   •   •   • 

.13 

•   •  •   • 

.02 

•   •   •   • 

.04 

.08 

.03 

26... 

.17 

.15 

.09 

.12 

•   •   •   • 

.01 

.08 

.13 

.04 

■   •   •   ■ 

27. . . 

.13 

.16 

.11 

.03 

.08 

.05 

.10 

.06 

.11 

.10 

28... 

.03 

.11 

.02 

.09 

.04 

.04 

.07 

.07 

.02 

.08 

29... 

.09 

.16 

.19 

.01 

.06 

.05 

.02 

.05 

.06 

.09 

•   •   •   ■ 

30... 

.07 

.12 

.25 

.08 

.04 

.04 

.11 

•   •   •   • 

•    •   •   • 

.09 

.04 

•   •  •  • 

81... 

.24 

•   •   •   • 

.05 

.  • .  • 

•   •   • 

.03 

•   •   •    ■ 

•   •   •   • 

•   •   •   • 

.06 

.05 

•   •   •  • 

Mean 

.125 

.110 

.109 

.089 

.070 

.056 

.063 

.062 

.060 

.060 

.066 

.067 

Total 

3.88 

3.30 

3.38 

2.67 

2.17 

1.74 

1.89 

1.92 

1.80 

1.87 

2.05 

1.88 

EVAPORATION,  GREYTOWN,  NICARAGUA,  1898. 


Day. 

Jan.           Feb. 

Mar. 

\pr.           May.        June.        July 

AujJT            Sept.           Oct.           Nov.            Dec. 

1 

.01 

04 

.13 

.18 

■   •   •                    ■   •   • 

.24 

•   •   •   •                        • 

•   •   •                        • 

.10 

o 

.21 

.08 

.25 

.25 

•   •   •   •                        • 

•   •   •                        ■ 

■   •   •                       •   •   •   • 

3 

.38 

.04 

.10 

»                        •   •   •   « 

•   •   •   •                        • 

•   •    •                        • 

.03 

4 

5 

.08 

•   •   • 

.05 

.23 
.39 

.22 

• 

•  •   •  • 

.20 

•  •   •   • 

k     •     •    • 

•     •    •     • 

.05 

.21 

.08 

•   •   •                        • 

|.15 

6 

.06 

.11 

7 

.06 

•   •  • 

.37 

•  •  •   • 

.25 

»   •   •                        • 

.14 

o     .      ... 

.44 

.25 

.08 

•   •   •   • 

.10 

02 

.05 

9 

.... 

.20 

•      •       •      •                                                 4 

.27 

f                       •   •   •   • 

•   •   •   • 

.05 

04 

10 

.05 

.19 

•      •      •      •                                                  « 

•   •   •                        • 

•   •   •                    • 

•   •   •   ■ 

.10 

»  •   •                        • 

•   •   •                        •   •  •   • 

11 

04 

.20 

.20 

.06 

•  •   •   • 

.15 

■   •                        • 

.08 

12 

.03 

.27 

.35 

.35 

•  •  •   • 

»  •   •   •                            ■ 

17 

,07 

13 

....            .  < 

»  •  • 

.30 

.18 

.27 

•   •   •                            • 

06 

.04 

14 

.13 

19 

.35 

.27 

•   •   •   «                       t 

•   •   •                        ■   1 

•  •                        • 

.15 

15 

.09 

•   • 

.40 

.10 

.10 

.10 

04 

.la 

16 

.16 

30 

.25 

.30 

.39 

.30 

.20 

•   ■                        • 

.09 

17 

.21 

13 

.18 

.06 

•   •   •                    • 

.01 

.15 

•   •                        • 

.10 

18 

.05 

15 

.25 

.20 

•   •                       ^ 

.15 

.10 

07 

.04 

19 

.06 

19 

.30 

.10 

.03 

.10 

•   •   •                            « 

12 

.15 

20 

04 

12 

.20 

.20 

.28 

.84 

.10 

10 

.OS 

21 

•  •  •   • 

12 

.15 

.20 

.13 

.08 

.07 

02 

.11 

22 

.08 

14 

.23 

•   •   • 

.07 

.10 

13 

.03 

23 

.09 

28 

.19 

•   •   • 

.35 

.15 

12 

.07 

24 

.10 

13 

.21 

.25 

•   •   •                    • 

.15 

14 

.13 

25 

.13 

15 

.08 

.12 

.40 

.25 

... 

•   •                        • 

.15 

26 

•   •   •    ■                            I 

18 

.27 

.10 

.05 

.30 

13 

.09 

27 

28 

.09 
.37 

•   • 

15 

.17 
.30 

.05 
.39 

.05 
.05 

.05 
.10 

•   •   •                        «  • 

07 

•  •                        • 

:::    {■'• 

29 

.23 

•   • 

.30 

.40 

.05 

.25 

■   •   •                        •   • 

•   •                        • 

*    •    •                             •    •    •    • 

30 

.25 

•   • 

•   •   •   1 

.15 

.05 

....            . 

•  •   •                       •   • 

•  •                        • 

.09 

31 

.18 

■   • 

•   •   •    •                        • 

•   •   • 

.23 

.18 

•  •   •                        •  • 

•   •                        • 

.07 

Mean. . . 

.138 

161 

.238 

.193 

.177 

.178 

.125 

096 

.083 

Total . . . 

4.28           4. 

51 

7.38           5 

.79           S 

».49 

5.52           .^ 

{.75           2. 

98 

3.57 

APPENDIX   III.— HYDROGRAPHIC   REPORT 


291 


Water  Supply. 

In  contemplating  any  canal  in  which  locks 
are  to  be  used  the  first  question  occurring  to  the 
investigator  is  with  regard  to  the  adequacy  of 
water  supply;  and  in  a  country  with  a  dry  sea- 
son as  definite  and  prolonged  as  that  of  the  region 
tributary  to  Lake  Nicaragua,  storage  of  water 
must  be  provided  against  evaporation,  leakage 
and  use  during  the  dry  season.  The  Nicaragua 
Canal  project  is  exceedingly  fortunate  in  hav- 
ing at  its  summit  level  Lake  Nicaragua,  a  mag- 
nificent 'natural  reservoir,  fed  by  an  ample 
drainage  basin.  This  reservoir  is  useful  not 
only  for  storing  water  for  use  of  the  canal,  but 
also  as  a  regulator  for  the  control  of  great  floods 
that  could  hardly  be  provided  for  at  practicable 
cost  without  its  aid.  On  the  other  hand,  the 
lake  exposes  its  vast  surface  of  two  million  acres 
of  tVater  to  the  constant  action  of  the  trade 
winds,  and  observations  indicate  that  the  lake 
loses  about  17,000  cubic  feet  per  second  by 
evaporation  during  the  dry  season. 

All  proposed  plans  for  the  canal  involve  the 
use  of  Lake  Nicaragua  as  part  of  the  sailing 
course,  and  the  conversion  of  a  portion  of  the 
San  Jiian  river  and  of  the  canal  through  the 
AVestem  Divide  cut,  into  arms  of  the  lake. 
A  course  of  about  twelve  miles  in  the  present 
lake  will  require  deepening,  about  thirty  miles 
of  river  will  require  dredging,  and  nine  miles  of 
heavy  excavation  will  be  made  on  the  west  side 
to  provide  for  a  sufficient  depth  for  navigation, 
below  the  minimum  level  to  which  the  lake  will 
be  permitted  to  go.  Every  foot  that  the  eleva- 
tion of  the  summit  level  is  allowed  to  decline, 
therefore,  involves  a  foot  of  excavation  or  dredg- 
ing through  about  fifty  miles  of  canal,  and  the 
financial  inducements  are  strong  for  holding  the 
minimum  as  high  as  practicable.  On  the  other 
hand  there  is  an  upper  limit  to  the  height  that 


the  lake  surface  niav  be  allowed  to  attain,  be- 
yond  which  great  damage  will  be  done  to  the 
lands  and  settlements  around  the  lake.  Thus  it 
is  necessary  to  assign  definite  limits  as  narrow 
as  practicable  between  which  the  lake  is  to  be 
held. 

From  evidence  of  the  inhabitants  of  Granada 
it  is  deduced  that  the  highest  point  the  lake  has 
reached  during  the  past  forty  years  is  nearly  111 
feet  above  sea  level.  From  evidence  of  citizens 
at  San  Ubaldo  it  was  learned  that  the  lake 
reached  a  maximum  of  about  107.5  in  1893. 
This  is  probably  the  highest  point  the  lake  has 
reached  since  the  Rivas  rainfall  record  began, 
in  1880.  The  year  1897  shows  a  rainfall  of 
123  inches,  as  against  105  for  1893;  but  the 
lake  did  not  in  1897  reach  as  high  a  point  as  in 
1893.  The  cause  is  to  be  found  in  the  state  of 
the  lake  at  the  opening  of  the  rainy  season. 
That  of  1897  found  the  lake  at  the  lowest  point 
it  had  been  known  recently,  caused  by  a  suc- 
cession of  three  years  with  rainfalls  18  to  30 
inches  below  the  mean,  while  1893  was  preceded 
by  a  rainfall  for  1892  over  ten  inches  above  the 
mean,  and  for  1891  slightly  below,  so  that  the 
lake  must  have  been  somewhere  about  its  nor- 
mal stage.  The  rainfall  record  does  not  indicate 
any  likelihood  that  the  lake  reached  any  stage 
higher  than  that  of  1893. 

It  may  be  said,  therefore,  that  the  lake  has 
been  known  to  rise  to  an  elevation  of  nearly  111, 
but  that  ordinary  wet  years  it  does  not  reach  108. 

The  rise  of  111  inundated  considerable  im- 
proved property,  and  submerged  large  areas  of 
land  which  at  present  is  unused  except  for  pas- 
turage. As  the  water  reaches  that  point  but 
once  in  more  than  a  generation  or  perhaps  in  a 
century  it  could  not  be  allowed  to  rise  so  high 
every  year  without  involving  heavy  damages. 
Jt  is  somewhat  difficult  to  determine  with  present 


292 


NICARAGUA   CANAL  COMMISSION 


in  formation  just  how  high  it  would  be  advisable 
to  allow  the  lake  to  rise  everv  vear,  but  it  eer- 
tainly  ought  not  to  be  higher  than  110.  This 
would  inundate  some  land  of  value  at  Granada, 
and  large  areas  along  the  east  and  south  of  the 
lake,  which,  though  having  no  present  value,  are 
susceptible  of  cultivation  and  improvement,  but 
it  would  avoid  any  heavy  bills  for  damages  to 
property.  The  construction  of  the  canal  on  a 
plan  contemplating  inundation  to  110,  would  not 
prevent  deepening  at  any  future  time  that  it  is 
desired  to  reclaim  submerged  land.  For  present 
purposes  we  assume  the  maximum  limit  as  110. 
In  fixing  the  lower  limit  it  is  necessary  first 
to  examine  the  conditions  of  water  supply.  If 
there  is  any  considerable  period  during  which 
the  inflow  is  less  than  the  evaporation,  water 
must  be  stored  to  compensate  for  the  loss,  to  pre- 
serve the  required  depth  for  navigation. 

Amount  of  Storage  Necessary. 

To  determine  the  inflow,  measurements  were 
made  during  the  dry  season  of  1898,  with  a  re- 
sult showing  that  only  two  streams  were  bringing 
any  considerable  quantitv'  of  water  into  the  lake, 
and  that  the  total  inflow  was  about  10  per  cent, 
of  the  evaporation  taking  place  at  the  same  time. 
Nearly  all  the  streams  inspected  showed  evi- 
dences of  having  been  stagnant  a  long  time,  the 
water  being  foul  and  dark-colored,  with  much 
vegetation  growing  upon  it,  which,  not  being 
rooted  to  the  soil,  would  have  passed  out  into 
the  lake,  had  there  been  any  considerable  cur- 
rent. If  this  condition  existed  in  1898,  a 
year  of  more  than  average  rainfall,  there  must 
be  several  months  during  ordinary  years  which 
furnish  very  little  water  to  the  lake.  The  rainy 
season  usually  closes  some  time  in  December,  the 
mean  rainfall  during  that  month  at  Rivas  being 
only   1.29   inches.     In   1898   the  rainy  season 


began  about  the  middle  of  May,  which  is  un- 
derstood, to  be  about  the  normal  time.  This 
is  well  shown,  in  the  diagram,  Plate  XV.  It 
may  be  said  in  general  that  the  rainy  season  is 
slightly  longer  than  the  dry  season,  but  in  years 
of  minimum  rainfall  this  relation  is  reversed. 
The  maximum  evaporation  in  the  diy  season  is 
over  6  inches  per  month;  in  the  rainy  season  it 
is  much  less,  and  in  the  early  part  of  the  drv  sea- 
son is  probably  less  than  6  inches.  It  may  be 
assumed  that  for  some  time  after  the  close  of 
the  rainy  season  the  inflow  to  the  lake 'will  con- 
tinue equal  to  or  greater  than  the  evaporation. 
It  certainly  would  not  be  extravagant  to  assume 
that  there  are  four  months  in  which  evaporation 
exceeds  the  inflow  by  an  average  of  six  inches 
per  month.  In  other  words,  for  the  normal 
diy  season  we  should  provide  two  feet  in  depth 
of  storage  to  make  good  the  ravages  of  evap- 
oration,* and  if  105  is  to  be  adopted  as  the  min- 
imum summit  level  to  be  allowed,  the  elevation 
of  the  lake  at  the  beginning  of  the  dry  season 
should  not  be  less  than  107. 

Tliis  provision  against  evaporation  might  be 
sufficient  if  we  could  be  sure  that  in  any  cycle 
of  twelve  months  the  inflow  to  the  lake  was 
greater  than  the  evaix>ration  during  the  same 
twelve  months,  but  unfortunatelv  no  such  assur- 
ance  can  be  given.  AVhile  the  mean  annual 
rainfall  in  the  basin  is  much  gi^eater  than  the 
evaporation,  as  proved  both  by  the  measured 
quantities  of  evaporation  and  rainfall,  and  by 
the  fact  that  water  is  always  being  discharged 
through  the  San  Juan  river,  there  is  in  this 
basin,  as  in  all  other  regions,  a  disparity  in  pre- 
cipitation between  the  dryest  and  the  wettest 
year  which  forbids  the  consideration  of  averages 
in  any  such  problem.  For  purposes  of  storage 
against  evaporation  we  must  consider  the  years 
of  minimum  inflow  and  maximum  evaporation. 


APPENDIX  III.— HYDROGRAPHIC   REPORT 


293 


For  purposes  of  computiiiia:  spillway  capacity  we 
must  coDsider  vears  of  maximum  inflow  coinci- 

t 

dent  with  minimum  evaporation.  The  data  on 
this  point  consist  of  a  series  of  rainfall  observa- 
tions at  Rivas,  extending  from  January,  1880, 
to  October,  1808,  reported  by  Dr.  Earl  Flint, 
and  the  short  records  taken  bv  the  Commission. 
The  year  of  minimum  rainfall  shown  by  the 
record  at  Tfivas,  is  1890,  in  which  31.81  inches 
fell.  The  rainy  season  in  1898  began  about  the 
middle  of  !N[ay.  During  May  and  June  of  this 
vear  85.12  inches  of  rain  fell  at  Rivas,  or  3.31 
inches  in  excess  of  the  total  for  1890.  The 
amount  of  water  received  by  Lake  Nicaragua 
from  May  1 5  to  June  30  in  excess  of  evaporation 
was  about  sufficient  to  raise  the  lake  two  feet. 
If  the  evaporation  in  this  time  be  taken  as  8 
inches  we  have  a  gross  inflow  of  2  feet  and  8 
inches,  as  the  yield  of  the  basin  for  this  rainfall. 
The  run-off  of  the  given  precipitation  is  much 
greater  when  concentrated  within  the  period  of 
45  davs  than  it  would  have  been  if  distributed 
over  a  period  of  six  months,  but  on  the  other 
hand,  if  no  rain  had  fallen  during  July,  a  con- 
siderable quantity  of  water  w^ould  doubtless  have 
flowed  into  the  lake,  as  the  result  of  June  pre- 
cipitation. This  would  probably  more  than 
compensate  for  the  excess  due  to  the  concentra- 
tion of  the  rainfall  above  mentioned,  and  to  the 
fact  that  35.12  inches  exceeds  the  rainfall  of 
1890  by  over  three  inches.  Suppose  we  allow 
four  inches  depth  for  the  July  nm-off  due  to 
June  rainfall.  We  have,  then,  as  the  run-off 
for  the  May  and  June  rainfall  sufficient  water 
to  raise  the  lake  three  feet,  if  it  had  been  isolated 
and  evaporation  eliminated.  The  evaporation 
during  a  diy  year  could  not  be  much  below  60 
inches;  this  leaves  a  deficit  of  two  feet,  which, 
under  the  above  assumption,  the  minimum  year 
would  have  wanted  of  supplying  sufficient  water 


to  compensate  for  evaporation.  The  year  1885 
shows  a  rainfall  of  34.59  inches,  so  that  the  vear 
1890,  though  the  minimum  in  the  record,  is  not 
an  especially  anomalous  case,  and  other  years  of 
as  small  or  even  smaller  rainfall  should  be  ex- 
])ected  and  provided  for. 

The  mean  rainfall  on  the  lake  surface,  taking 
the  records  of  l^as  Lajas,  San  Carlos,  Tipitapa 
and  San  Ubaldo,  is  23.18  inches  during  this 
time,  made  up  as  follows: 

San  Carlos 21.08 

Las  Lajas 23.93 

Tipitapa 25.44 

San  Ubaldo 22.25 

Mean 23.18 

None  of  these  records  show  as  great  a  rainfall 
as  that  n^ported  for  Rivas,  by  about  ten  inches. 
This  is  the  more  remarkable  as  the  station  at 
Las  Lajas  is  hardly  seven  miles  from  Rivas. 

The  conditions  at  Rivas  may  have  been  local 
and  anomalous,  and  the  conclusions  drawn  from 
the  above  estimate  cannot  be  considered  as  final, 
but  they  are  sufficient  to  indicate  that  the  ade- 
quacy  of  the  annual  water  supply  is  at  least 
doubtful. 

To  approach  the  problem  from  the  other  side, 
supj)ose  the  mean  rainfall  for  the  basin  of  Lake 
Nicaragua  for  the  minimum  year  to  be  two  feet. 
This,  if  all  held  and  evaporation  eliminated, 
would  raise  the  lake  t\vo  feet  by  precipitation 
<Hrectly  upon  it.  To  this  should  be  added  the 
probable  run-off  from  the  drainage  area,  but  in 
this  we  should  not  include  the  drainage  of  Lake 
Managua.  It  is  said  that  at  times  this  lake  con- 
tributes no  water  to  Lake  Nicaragua  for  several 
years,  and  there  certainly  must  be  years  when  its 
contribution  is  so  low  that  we  should  not  con- 
sider it  in  an  estimate  of  this  kind.  Taking  the 
area   directly   tributary   to  Lake  Nicaragua   as 


294 


NICARAGUA   CANAL  COMMISSION 


6000  square  miles  and  the  run-off  for  two  feet 
of  rainfall  at  25  per  cent.,  the  lake  would  re- 
ceive sufficient  water  from  its  tributary  area  to 

ft, 

raise  it  one  foot,  which,  added  to  that  falling 
directly  upon  the  lake,  gives  us  three  feet  as  the 
total  yield  of  two  feet  of  rainfall,  which  agrees 
with  the  estimate  deduced  from  recorded  obser- 
vations on  the  lake,  and  leaves  a  deficit  of  two 
feet. 

Since  a  year  is  likely  to  occur  in  which  evap- 
oration and  use  exceed  the  inflow  by  two  feet, 
that  year  must  be  commenced  with  a  water  level 
two  feet  above  the  minimum  elevation  which  is 
to  be  permitted.  As  it  is  impossible  at  present, 
and  will  always  be  imiK)ssible,  to  predict  just 
when  that  year  of  minimum  inflow  and  maxi- 
mimi  evaporation  is  likely  to  occur,  the  effort 
should  always  be  to  maintain  the  summit  level 
at  two  feet  above  the  minimimi.  To  reach  a 
conclusion  as  to  the  elevation  at  which  the  lake 
surface  should  be  held  at  any  given  time  in  order 
to  insure  against  its  decline  below  the  minimum 
level,  let  us  assume  a  state  of  climate  in  which 
the  inflow  is  always  greater  than  the  evaporation 
during  any  twelve  months.  As  above  stated, 
the  evaporation  in  excess  of  inflow  in  the  normal 
dry  season  is  estimated  at  two  feet.  It  would 
be  necessary,  therefore,  at  the  end  of  each  rainy 
season  to  hold  the  summit  level  two  feet  above 
the  minimum  summit  level.  If  this  be  105 
then  the  nile  would  be  to  enter  the  drv  season 
witli  the  level  at  107,  the  estimate  being  that  by 
the  time  rains  begin  in  May  this  surplus  water 
would  be  evaporated  and  the  summit  level  would 
stand  at  105.  Xow  suppose  that  in  the  ensuing 
year  the  evaporation  and  leakage  should  ex- 
ceed the  inflow  by  two  feet,  the  natural  decline 
in  summit  level  would  bring  it  down  to  103, 
and  to  avoid  this  state  of  affairs  the  lake  should 
bo  held  at  the  opening  of  the  drj-  season  not  at 


107  but  at  109.  The  indications  are,  therefore, 
that  the  minimum  range  within  which  the  lake 
can  be  controlled,  having  regard  to  evaporation 
only,  is  not  l(?ss  than  four  feet. 

Spillway  Capacity. 

As  nearly  as  can  be  determined  by  the  obser- 
vations at  hand,  the  maximum  rise  in  the  lake 
in  4.^  hours,  if  all  had  been  held,  was  about  .44 
of  a  foot.  This  indicates  an  inflow  of  about 
220,000  cubic  feet  per  second.  It  would  be 
neithcn*  necessarv'  nor  economical  to  provide  a 
spillway  of  this  capacity,  but  would  be  far 
cheaper  to  allow  temporary  storage  for  such 
floods  as  this  and  others  somewhat  greater. 
Five-tenths  of  a  foot  is  therefore  allowed,  \vhich 
is  to  be  subtracted  at  the  outset  from  the  limit 
assigned  for  the  control  of  the  lake  in  any- 
given  season. 

If  the  limits  set  be  105  minimum  and  110 
maximum,  and  w-e  deduct  two  feet  from  the 
lower  limit  as  being  a  permanent  reserve  against 
an  unusually  dry  year,  and  .5  foot  from  the 
upper  limit  for  sudden  inflow  as  herein  de- 
scribed, we  have  as  a  spillway  problem  the  con- 
trol of  the  inflow  of  the  year  of  maximum  rain- 
fall  between  the  limits  of  2.5  feet 

In  attempting  to  deduce  the  necessary  ca- 
pacity of  a  spillway  to  discharge  the  surplus 
water  flowing  into  Lake  Nicaragua,  we  have 
recourse  to  the  comparison  of  the  observations 
taken  in  1898  with  the  long  record  of  rainfall 
at  Rivas.  This  record  indicates  that  the  max- 
imum annual  precipitation  in  19  years  was  for 
the  year  1897,  123.43  inches.  Comparing  the 
record  at  the  same  plac^  for  1S9S,  up  to  October 
31,  with  that  for  the  corresponding  months 
of  1897  we  find  that  the  precipitation  for  1808 
is  83  per  cent  of  that  for  1897.  In  other  words, 
the  precipitation  for  1898  should  be  increased 


NICARAGUA  CANAL  COMMISSION 


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FEenUARY 


APRIU  MAY  JUNE  JULY  AUG 

DIAGRAM    OF  THE    DAILY   MEAN    ELEVATION   OF   LAKE    NICi 


APPENDIX  3,  PLATE  XVIII 

SEPTEMBER  OCTOBCR  NOVEMBER  DCCEMBCR  JANUARY  FEBRUARY  MAUCH  APRIL 


— — . — .  y  ? — 1 — 1 — r— ¥-¥ — r-f-  Tj-i — 1  y  f  T  f — .  y  ?  f  ? — i— f~HH — ;  -f  i  ?  i ,  •?  y-y-y 

1*   S3--  IB    )8 

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lUlililULJJiLlLii.L.  iJju^j^..LLiLi.i.,  J  _  ,,_ 

SEPTEMBER  OCTOBER  NOVEMBER  DECEMBER 

COMPARED  WITH   THE  SYNCHRONOUS  RAINFALL  IN    ITS  BASIN. 


FEBRUARY  MARCH 


APPENDIX  III.— HYDROGRAPHIC   REPORT 


295 


21  per  cent,  to  be  equal  to  that  of  the  maximum 
in  the  record.  AVhile  we  have  no  conclusive 
data  upon  which  to  estimate  the  percentage  of 
run-off  to  rainfall  in  the  basin  of  Lake  Nica- 
ragua, yet  it  is  well  established  as  a  general  rule 
that  in  any  given  basin  the  greater  the  rainfall 
in  a  given  time,  the  greater  the  percentage  of 
run-off,  so  that  if  the  rainfall  were  increased 
21  per  cent,  the  run-off  should  be  increased 
somewhat  more,  say  25  per  cent.  Now  the 
run-off  for  the  basin  of  Lake  Nicaragua  has  been 
measured  for  1898  up  to  the  27th  day  of  Octo- 
ber. From  June  15  to  October  27  the  lake 
received  in  excess  of  evaporation  13,450,000 
acre-feet  of  water,  5,450,000  of  which  were  dis- 
charged through  the  San  Juan  river  and  8,000,- 
000  were  stored  in  the  lake.  This  is  equivalent 
to  a  mean  inflow  in  excess  of  evaporation  of 
50,700  cubic  feet  per  second.  Lf  this  inflow  be 
increased  by  25  per  cent,  to  make  it  correspond 
with  that  of  the  hypothetical  maximum  year  we 
have  a  mean  influx  of  63,375  cubic  feet  per  sec- 
ond, which  if  continued  for  183  days  would  have 
contributed  a  total  of  23,005,400  acre-feet.  If 
we  limit  the  rise  in  the  lake  during  this  time 
to  2.5  feet  we  find  the  required  spillway  capacity 
to  be  49,680  cubic  feet  per  second.  It  seems, 
therefore,  that  a  spillway  capacity  of  50,000 
cubic  feet  per  second  would  have  kept  the  lake 
within  the  desired  limit  during  the  year  of  max- 
imum rainfall  as  above  computed.  Under  the 
same  conditions,  the  rise  could  have  been  limited 
to  1.5  by  a  spillway  of  56,000  cubic  feet  ca- 
pacity. 

The  question  now  arises  whether  there  is  any 
reason  to  believe  that  rainfall  during  the  maxi- 
mum year  is  likely  to  be  so  concentrated  within 
a  short  period  as  to  be  greater  than  the  capacity 
of  our  spillway  to  care  for.  Our  only  recourse 
is  to  the  rainfall  observations  during  the  maxi- 


mum year.  Here  we  find  that  during  October, 
1897,  33.85  inches  of  rain  fell,  which  is  more 
than  one-fourth  of  the  total  for  that  vear  and 
exceeds  by  nearly  50  per  cent,  the  precipitation 
for  any  other  one  month  in  the  entire  record 
of  19  years.  Such  a  rainfall  coming  near  the 
close  of  the  rainy  season  when  Lake  Managua 
and  tributarv  streams  are  full  and  the  ground  is 
generally  saturated,  might,  it  seems,  well  be 
taken  as  the  most  unfavorable  condition  likelv  to 
occur.  An  examination,  therefore,  of  the  re- 
sults which  would  have  followed  such  a  year  as 
1897,  with  our  estimated  spillway  capacity  un- 
der perfect  control,  should  indicate  whether  or 
not  our  works  or  property  on  the  lake  would 
have  been  damaged  in  that  maximum  year. 

The  inflow  to  Lake  Nicaragua  between  May 
15  and  September  30  was  12,525,000  acre-feet 
in  excess  of  evaporation.  The  rainfall  during' 
these  months  was  exceeded  by  that  in  the  corre- 
sponding months  of  1897  by  about  10  per  cent. 
The  coiTcsponding  run-off  for  1897  would, 
therefore,  have  exceeded  that  for  1898  by  a 
somewhat  larger  percentage,  say  12  per  cent. 
This  would  give  an  inflow  for  1897  up  to  the 
30th  of  September  of  14,028,000  acre-feet. 
Tliis  is  equivalent  to  a  mean  inflow  of  about 
51,000  cubic  feet  per  second.  A  spillway  of 
50,000  cubic  feet  per  second  discharging  all  the 
time  would  have  confined  the  rise  to  .28  foot; 
then  we  still  have  a  limit  of  2.2  feet  which  the 
lake  can  rise  during  October  before  reaching  the 
danger  line.  During  May  and  June,  1898, 
35.12  inches  of  rain  fell  at  Rivas  and  the  inflow 
was  about  4,000,000  acre-feet,  exclusive  of  evap- 
oration. The  rainfall  during  October,  1897, 
was  33,85  inches,  or  1.27  less  than  during  May 
and  June,  1898.  The  run-off,  however,  would 
have  been  greater  owing  to  the  fact  that  the  rain 
for  May  and  June  fell  upon  dry  land  and  was 


296 


NICARAGUA  CANAL  COMMISSION 


largely  absorbed,  and  Lake  ^Managua  and  its 
drainage  area  contributed  practically  nothing  to 
Lake  Nicaragua  during  that  time,  while  in  1898 
Lake  ^Managua  contributed  during  October  a 
total  of  nearly  250,000  acre-feet,  and  the  same 
influence  would  have  operated  in  a  less  degree 
to  increase  the  inflow  from  all  tributaries  of 
Lake  Nicaragua  during  October  over  what  it 
was  during  ^fay  and  June.  Making  due  allow- 
ance for  th(^  lesser  rainfall  in  October  and  the 
greater  proportional  run-off,  it  would  seem  that 
to  allow  ten  per  cent,  increased  inflow  over  that 
for  May  and  June,  1898,  would  be  sufticient, 
and  this  would  just  bring  the  hike  to  101). 5;  and 
for  the  spillway  capacity  to  prevent  further  rise 
we  must  assume  the  inflow  to  be  no  greater  than 
50,000  cubic  feet  per  second.  As  the  Kivas 
rainfall  for  November,  1897,  is  but  5.15  inches, 
and  exceeds  the  mean  for  that  month  bv  about 
14  per  cent.,  this  seems  to  be  a  safe  assumption. 
It  will  be  observed,  however,  that  this  pre- 
supposes the  opening  of  the  spillway  to  its  full 
capacity  throughout  the  seas<jn,  allowing  the  lake 
to  rise  less  than  .3  foot.     But  it  must  be  borne 

in  mind  that  the  heavv  rainfall  for  October  could 

* 

not  be  predicted  for  any  specific  year,  and  as 
it  is  necessary  to  hold  the  lake  at  109  at  the 
end  of  the  rainy  season,  as  above  indicated,  it 
would  not  be  safe  to  penuit  the  level  to  remain 
so  low  at  the  end  of  September,  unless  the  rain- 
fall after  that  date  can  l>e  depended  upon  to 
supply  the  necessary  storage,  namely,  1.7  feet. 
The  snialle>^t  rainfall  in  tin*  record  for  October, 
November  and  December,  in  any  one  year,  is 
that  for  1895,  when  11.21  inches  fell,  which  it 
seems  l)y  comparison  with  this  year's  record 
would  have  raised  tlie  lake  about  a  fo<:)t.  The 
run-off  due  to  previous  rainfall  would  have  been 
considerable,  at  least  .2  foot,  so  that  we  would 
lack  .5  foi>t  of  having  the  desired  reserve  storage. 


and  it  would  be  necessarj'  to  begin  October  with 
a  lake  level  not  lower  than  107.8.  The  year  of 
heavy  rainfall  according  to  the  above  estimates, 
would  have  carried  the  level  to  just  110,  the 
extreme  limit. 

Tn  view  of  the  fact  that  such  extreme  condi- 
tions as  we  have  been  assuming  occur  very  sel- 
dom, and  that  the  lake  has  risen  in  past  years 
above  110  from  natural  causes,  an  error  of  judg- 
ment in  the  manipulation  of  the  spillway  which 
should  allow  the  surface  to  rise  a  few  inches 
above  the  limit  set,  could  not  be  regarded  as 
doing  more  than  repeating  the  results  of  nature. 

Value  ok  the  Estimates. 

The  data  upon  which  the  above  estimates  are 
necessarily  made  are  meager,  and  it  becomes  im- 
portant to  form  an  idea  as  definite  as  may  be  re- 
garding their  value. 

The  extensive  use  which  is  made  of  the  record 
of  Rivas  rainfall  involves  to  an  important  de- 
gree the  question  of  the  probable  integrity  and 
reliabilitv  of  that  record.  The  obser\'ations  were 
taken  bv,  or  under  the  authoritv  of,  Dr.  Earl 
Flint,  a  thoroughly  competent  observer,  and  the 
record  in  itself  contains  no  indication  of  being 
faulty.  AVhile  the  range  between  maximum 
and  minimum  rainfall  might  appear  to  be  large, 
it  is  not  so  large  in  percentage  as  in  many  records 
taken  in  the  United  States.  AVithout  further 
evidence  pro  or  con  the  record  might  be  consid- 
ered good,  at  least  as  good  as  rainfall  records 
usually  are.     A  comparison  of  the  records  at 

Rivas  and  at  ilasiiva  and  Granada  shown   in 

t. 

diagram  (Fig.  8)  exhibits  a  striking  parallelism 
with  no  discrepancies  greater  than  might  be  ex- 
pected from  stations  located  relatively  as  these 
are.  The  somewhat  sui-prising  fact  that  the 
rainfall  obser\'ed  at  Kivas  for  1898  is  much 
greater  than  that  at  any  of  the  stations  main- 


NICARAGUA  CANAL  COMMISSION 


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DIAGRAM  OF  THE  DAILY  MEAN  INFLOW  TO  LAKE  NICARAGUA  COMPARED  WITH  THE  MEAN  RAINFALL  II 

THE  DOTTED  LINE    INDICA 


TEMBER  OCTOBER  NOVEMBER  DECEMBER  JANUAI 


APPENDIX  3,  PLATE  XtX 
ARY  MARCH 


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M.     THE  CONTINUOUS  LINE  INDICATES  THE  ELEVATION  OF  THE   LAKE  IF  ALL  WATER   HAD   BEEN    HELD. 
ACCUMULATED  RAINFALL. 


APPENDIX   III.— HTDROGRAPHIC   REPORT 


297 


tained  by  this  Commission  in  the  vicinity,  also 
appears  in  the  diagram,  which  shows  that  it  is 
also  greater  than  that  taken  at  Masaya  and  Gra- 
nada, in  nearly  every  year  of  the  record.  The 
inference,  therefore,  is  that  from  natural  causes 
the  rainfall  at  liivaa  actually  is  greater  than  in 
most  other  parts  of  the  basin,  due  probably  to 
local  meteorologic  conditions,  but  these  local 
conditions  do  not  vitiate  the  record  as  a  means 


assumption  that  the  Rivas  rainfall  bears  a  fixed 
rotation  to  that  of  the  entire  basin,  the  results 
could  not  be  relied  upon  within  narrow  limits. 
The  problem  presented,  however,  is  of  such  a 
character  that  the  conclusion  may  be  relied  upon 
within  very  much  narrower  limits  than  the  prob- 
able error  of  individual  estimates.  The  esti- 
mates for  spillway  depend  upon  the  assumption 
that  rhe  relation  of  the  rainfall  for  1898,  for 


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.  Comparative  rainfall  at  Rivas  and  Masara. 


of  comparison,  because,  as  the  diagram  indicates, 
they  still  bear  a  reasonably  uniform  relation  to 
the  stations  of  lesser  rainfall.  It  would  appear, 
therefore,  from  all  the  evidence  at  hanil,  that 
the  Eivas  record  may  be  used  as  safely  and 
within  as  wide  limits  as  any  rainfall  record  can 
be.  It  must  he  admitted,  however,  that  fluc- 
tuations of  rainfall,  local  and  spasmodic,  occur 
in  all  parts  of  the  world,  and  if  our  estimates 
depended  absolutely  upon  the  reliability  of  the 


which  we  have  a  measured  nui-off,  and  the  rain- 
fall for  l!^9T  is  tlic  relation  indicated  by  the 
Rivas  record.  If  from  temporary  causes  the 
Rivas  record  for  1898  is  too  large,  then  its  as- 
sumed relation  to  the  maximum  year  is  too  large, 
and  we  will  have  greater  floods  than  those  esti- 
mated and  will  need  either  a  wider  limit  of 
fluctuation  in  the  lake  or  greater  capacity  of 
spillway.  But  under  the  same  supposition  we 
have  also  estimated  too  small  a  rainfall  for  the 


298 


NICARAGUA  CANAL  COMMISSION 


dry  years  and  the  provision  for  storage  against 
such  years  is  estimated  too  large.  Here,  then, 
we  have  two  errors  which  tend  to  counterbalance 
each  other.  Conversely,  if  from  temporary 
causes  the  rainfall  at  Rivas  was  abnormallv  small, 
we  have  the  reverse  result  in  both  cases,  but  still 
the  two  errors  tend  to  counterbalance  each  other, 
and  it  is  believed  that  the  facts  known  are  suf- 
ficient to  indicate  with  all  necessary  accuracy 
the  limits  within  which  the  lake  can  be  con- 
trolled, and  the  spillway  capacity  necessary  for 
the  purpose. 

The  conclusion,  therefore,  is  that  the  lake  can 
probably  be  controlled  within  limits  of  five  feet, 
if  an  adjustable  spillway  be  provided  with  a  ca- 
pacity of  50,000  cubic  feet  per  second.  The 
excavation  required,  however,  is  such  that  if 
the  limit  could  be  reduced  to  four  feet,  it  would 
save  one  foot  of  excavation  throughout  a  large 
part  of  the  summit  level,  and  reduce  the  cost 
more  than  two  million  dollars. 

If  a  range  of  fluctuation  be  allowed  greater 
than  five  feet,  the  spillway  capacity  may  be  re- 
duced and  the  supply  for  dry  seasons  will  be 
made  more  se<jure. 

Lake  Managua. 

It  has  been  suggested  that  Lake  Managua 
might  be  utilized  as  a  reservoir  in  which  to  store 
a  portion  of  the  water  required,  at  a  less  cost 
than  it  could  be  stored  in  Lake  Nicaragua.  This 
lake  lies  to  the  north  and  west  of  Lake  Nica- 
ragua, has  a  surface  of  about  438  square  miles 
and  a  tributary  drainage  area  of  about  2500 
square  miles.  Its  surplus  waters  are  discharged 
into  Lake  Nicaragua  by  way  of  Tipitapa  river. 
One  mile  below  the  point  where  this  river  leaves 
Lake  Managua,  it  falls  over  a  cataract  descend- 
ing about  13  feet  in  a  horizontal  distance  of  500 
fet^t.     It  is  estimated  that  a  dam  might  be  con- 


structed at  this  point,  and  the  waters  of  Lake 
-Managua  raised  about  eight  feet  above  the  sur- 
face of  the  rock  at  the  falls  without  serious 
damage  to  property  around  the  margin  of  the 
lake.  An  outlet  tunnel  or  cut  might  be  provided 
to  draw  off  the  water  to  the  level  of  the  river 
below  the  falls.  All  these  works  would  be  in- 
expensive and  a  storage  capacity  would  thus  be 
secured  for  a  depth  of  20  feet  over  the  entire  sur- 
face of  Lake  Managua,  which,  if  drawn  off  in 
its  entirety  would  raise  Lake  Nicaragua  about 
three  feet.  To  further  test  the  merit  of  this 
proposition,  measurements  of  rainfall  and  out- 
flow were  made  at  Tipitapa  and  a  station  was 
established  on  Eio  Viejo  about  50  miles  north 
of  the  lake  for  the  measurement  of  rainfall  and 
of  the  discharge  of  the  principal  tributary  to 
Lake  Managua,  Eio  Viejo;  also  to  obtain  data 
regarding  the  regimen  and  discharge  of  Rio 
Nueva. 

The  cost  of  utilizing  Lake  ^Fanagua  as  a  stor- 
age reservoir  for  the  summit  level  would  be 
roughly  al>out  as  follows: 

Cost  of  overflow  ogee  dam  at  Tipitapa 

1600  yds.  concrete  at  $15 $24,000 

Excavation  of  outlet 20,000 

Gates  and  gatehouse 6,000  ' 

$50,000 
Diversion  of  Nueva: 

750,000  cubic  yards  earth  at  20  cents.  .$150,000 

Dam    100,000 

•  ^"^■~^* 

Total $300,000 

So  far  as  works  are  concerned,  this  project  is 
practicable  and  cheap,  but  the  water  supply  is 
doubtful.  It  is  known  that  entire  vears  some- 
times  occur  in  which  there  is  no  outflow  from  the 
lake,  but  on  the  other  hand,  the  fact  that  water 
does  often  flow  out  proves  beyond  question  that 


APPENDIX   III.— HYDROGRAPHIC   REPORT 


299 


in  the  long  run,  the  inflow  exceeds  the  evapora-  conclude  that  this  could  be  done.     The  storage 

tion  and  seepage  from  the  lake.  of  water  in  Lake  Managua  would  also  assist  in 

The  discharge  from  Lake  Managua  has  been  the  control  of  the  surplus  waters  by  reducing 

measured  for  the  year  1898,  excepting  for  the  the  area  of  the  watershed  to  be  provided  for. 
months  of  January  and   December.     Estimatr 

ing  the  discharge  for  these  two  months,  we  have  Sediment  Observations. 

a  total  outflow  for  the  year  of  something  over  Any  proposition  for  a  ship  canal  which  in- 

1,100,000  acre-feet,   or  enough  to  raise  Lake  volves  the  use  of  the  San  Juan  river  below  the 

Nicaragua  .55  foot,  or  to  raise  Lake  ilanagua  mouth  of  the  San  Carlos  requires  for  its  intelli- 

3.8  feet,  if  all  had  been  held.  gent  consideration  some  idea  of  the  quantity  of 

Had  Rio  Xueva  been  diverted  into  Lake  Man-  sediment  carried  by  that  stream,  and  if  the  San 
agiia  during  this  year,  as  suggested  on  page  208,  Juan  is  to  be  used  below  the  mouth  of  the  Sara- 
it  would  have  contributed  about  200,000  acre-  piqui  the  sediment  earned  by  that  stream  be- 
feet  more,  sufficient  in  all  to  have  raised  Lake  comes  also  an  important  factor.  To  determine 
Managua  about  4^  feet  in  excess  of  evaporation,  these  quantities  samples  of  water  were  taken 
or  enough  to  raise  Lake  Nicaragua  eight  inches,  daily,  allowed  to  settle,  and  the  sediment  meas- 
Though  the  precipitation  and  nm-off  of  1898  ured.  The  samples  were  taken  at  not  less  than 
were  probably  above  the  average,  still  it  would  a  dozen  places  in  the  river,  the  water  taken  ag- 
be  fair  to  expect  one  or  more  such  years  in  each  gregating  several  gallons,  and  representing  ap- 
interval  between  the  years  of  drought,  and  to  proximately  the  average  of  the  various  parts  of 
assimie  that  the  inflow  to  Lake  Managua  during  the  current.  The  samples  were  thoroughly 
the  other  years  would  on  an  average  be  equal  to  mixed,  and  one  sample  of  100  cubic  centimeters 

SEDIMENT  BY  WATER-SAMPLES  FROM  SAN  CARLOS  RIVER,  1898. 

Month.                                                 Mud.                        Solid  Matter.  Remarks. 

Cubic  >Tird8.  Cubic  yards. 

June 705,000  141,000                             5  cu.  yds.  mud  are  assumed  equal  to 

July 1,0.S«,000  837,200                         1  cu.  yd.  of  solid  matter. 

AuiTUst 77S/ioO  155,650 


the  evaporation.  If  this  assumption  be  correct, 
we  have  for  $300,000  a  storage  that  would  cost 
over  one  million  dollars  to  provide  in  Lake  Nica- 
ragua. The  information  at  hand  is  not  sufficient 
to  admit  any  conclusion  as  to  the  actual  quantity 
of  practicable  storage,  but  if  in  each  year  of 
extreme  drought  Lake  Managua  could  furnish  an 
amount  of  water  equal  to  18  inches  over  its  own 
surface,  its  storage  would  be  cheaper  than  the 
same  storage  capacity  provided  by  excavation 
along  the  canal  line.     It  seems  entirely  safe  to 


taken  from  the  mixture,  and  the  rest  rejected. 
The  sample  taken  was  allowed  to  settle  for  24 
hours,  the  clear  water  poured  oflF,  and  another 
sample  added  to  the  remainder,  the  clear  water 
was  decanted  the  next  day,  another  sample 
added,  and  so  on,  accumulating  any  sediment 
that  remained,  until  it  became  a  measurable 
quantity,  when  its  depth  was  read  on  the  grad- 
uated glass  in  which  the  settlement  was  made. 
This  reading  gives,  of  course,  only  the  bulk  of 
the  loose  mud,  and  not  the  dry  solid  matter. 


300 


NICARAGUA  CANAL  COMMISSION 


The  relation  beiween  tbe  mud  and  dry  matter 
as  detemiined  by  a  series  of  experinienta  for  a 
similar  purpose  made  on  sediment  from  the  Gila 
river,  Arizona,  was  five  parts  of  mud  to  one  of 
dry  material.  This  factor  has,  therefore,  been 
used  in  reducing  the  results. 

The  taking  of  wster  samples  and  measurement 
of  sediment  therein  would  not  furnish  all  the  re- 
quired data,  as  these  streams  roll  large  quantities 
of  sand  and  gravel  along  their  beds,  which  could 
not  be  taken  in  water  samples.     So  far  as  could 


in  a  ring,  and  the  whole  was  suspended  from  a 
cable  stretched  across  the  river,  with  the  door 
open  uijsitream.  An  anchor  was  thrown  about 
100  feet  Upstream  to  hold  the  pan  firmly  in  posi- 
tion, while  it  was  gently  lowered  from  the  cable 
by  means  of  a  rope  from  shore,  working  in  tackle 
blocks.  The  pan  was  allowed  to  settle  firmly 
on  the  bottom,  and  to  remain  for  a  limited  time, 
usually  one  hour.  The  attempt  is  to  cause  the 
minimum  disturbance  of  natural  conditions  in 
the  stream,  and  to  intercept  and  hold  in  the  pan 


Fin.  9.    The  Sediment  Trap  ready  for  u 


be  learned  no  attempt  at  such  measurements  had 
ever  been  made,  and  it  was  recognized  as  a  task 
of  difficulty.  The  method  devised  was  as 
follows: 

A  galvanized  sheet-iron  pan  was  provided  (see 
Fig.  9),  one  meter  square  and  eight  inches  deep, 
with  one  side  hinged  so  that  it  could  be  opened 
to  lie  in  the  same  plane  as  the  bottom  of  the  pan, 
and  a  weight  and  stays  were  provided  to  hold 
it  in  this  horizontal  position.  Four  chains,  at- 
tached one  to  each  corner  of  the  top  of  the  pan. 
met  about  four  feet  alii>ve  the  pan,  and  united 


the  nedinient  traveling  along  the  bottom  in  the 
section  it  occupies.  When  it  is  desired  to  close 
the  ol)servation,  a  small  copper  wire  which  has 
been  fa.stened  to  the  open  door  and  passed 
through  the  ring  above  the  pan,  is  stoutly  pulled 
until  it  raises  the  lid  from  the  bottom  of  the 
stream,  whereupon  the  current  catches  and  slams 
the  lid  shut,  where  it  is  automatically  fastened 
by  a  latch  on  each  side.  Then,  by  means  of  a 
windlass  on  shore,  the  pan  is  hoisted  and  brought 
to  land,  and  the  entrapped  sediment  measured. 
There  is  notliing  about  this  operation  to  in- 


APPENDIX   III.— HYDROGRAPHIC   REPORT 


302 


NICARAGUA  CANAL  COMMISSION 


crease  the  motion  of  sediment  along  the  bottom 
into  the  pan,  so  it  is  thought  that  results  can 
never  be  too  large.  On  the  other  hand  some 
sand  may  pass  under  the  edge  of  the  lid,  when 
the  bottom  of  the  river  at  this  point  is  marred 
with  local  inequalities.  This  is  supposed  to 'be 
one  cause  of  the  small  results  on  certain  days, 
when  other  observations  immediately  before  or 
after,  give  large  results.  Another  persistent 
source  of  error  of  unknown  magnitude  is  the 
washing  out  of  the  sediment  by  the  current  over 
the  weir  formed  by  the  back  of  the  pan.  To 
test  the  importance  of  this  theoretical  possibility, 
a  temporary  partition  was  placed  in  the  pan,  per- 
pendicular to  the  current,  and  nearly  as  high  as 
the  sides  of  the  pan,  the  theory  being  that  if 
all  sediment  were  stopped  by  the  partition  and 


deposited  in  front  of  it,  that  would  be  good  evi- 
dence that  in  the  absence  of  the  partition  all 
would  be  stopped  by  the  back  of  the  pan,  and 
none  lost.  In  the  first  experiment  more  sedi- 
ment was  deposited  behind  than  in  front  of  the 
partition,  and  the  quantity  that  passed  out  of  the 
pan  is  unknown.  This  result  was  essentially  re- 
peated for  most  of  the  experiments,  showing 
conclusively  that  more  or  less  sediment  is  car- 
ried out  over  the  back  of  the  pan  by  the  scour 
which  it  occasions.  It  is  important  to  bear  this 
fact  in  mind,  when  studying  the  results,  for  it  is 
certain  that  the  results  are  quantitatively  too 
small,  and  should  be  regarded  as  showing  that 
large  quantities  of  sediment  are  traveling  on  the 
bed  of  the  stream,  and  as  roughly  indicating  the 
relative  amount. 


SEDIMENT  ROLLED  ON  BOTTOM  OF  SAN  CARLOS  RIVER,  COSTA  RICA. 


Date. 

Mar.  29,  1898. 

Aprils? 

Mav      3 

'»      19 

»*      24 

JuDe  15 

*'      17 

''      20 

'i      30 

July    14 

»*      15 

'»      Irt 

^<-      10 

u       19 

»*      20    

'*      26 

*'      26 

"      27 

"      27 

Aug.     9 

"       10 

'«      10 

'*       11 

»»       11 

Oct.       8 

'*      20 

'*      22 

"      29 

Nov.      4 

*»        5 

'*      21 

'»      22 

'»      23 

Dec.      2 

«'        6 

"      15 


Oa^e  Amt.  collected 

height.         per  hr.  in  c.  c. 


Total  for  river    Mean  for  month       Total  cii. 
in  cu.  yds.  per       in  cu.  yds.  per         yds.  i)er 
hour.  hour.  month. 


Remarks. 


12.00 
11.34 
11.03 
12.05 
12.10 
12.60 
13.50 
14.40 
15.53 
14.93 
14.50 
14.30 
14.80 
14.10 
14.20 
13.20 
13.10 
13.00 
13.10 
13.30 
13.20 
13.10 
18.45 
13.60 
13.10 
15.90 
14.35 
14.83 
14.00 
13.50 
15.00 
14.70 
14.30 
18.60 
13.90 
13.55 


21,450 
40,610 
18,650 
31,475 
14,000 
16,040 
12,400 
12,400 
64,340 
35,300 
25,700 
20,600 
21,800 
21,000 
23,900 
26,460 
23;780 
46,400 
48,625 
21,300 
31,100 
88,210 

106,740 
59,230 
39,800 
53,000 

102,062 
87,950 
34,500 
30,965 

121,500 
82,270 

115,340 
52,950 

112,150 
38,190 


5.61 

12.19 

4.88 

8.23 

3.66 

19.90 

3.24 

3.24 

16.82 

9.23 

6.72 

5.39 

5.70 

5.50 

6.25 

6.92 

6.22 

12.13 

12.71 

5.57 

8.13 

23.07 

27.91 

15.48 

10.27 

13.86 

26.69 

22.87 

9.70 

8.10 

33.30 

8.80 

31.60 

13.80 

29.50 

10.00 


5.61 
12.91 


5.59 

*  *  ' '  !^ 

10.80 


68 


16.03 


18.42 


18.30 


4,174 
9,295 


4,159 


Coarse  sand 


5,714 


11,926 


13,704 


13,180 


it 


(I 


Gravel  and  sand 
Coarse  sand 
Gravel  and  sand 


(( 
(( 
k( 
11 
ii 
(( 
i( 
(( 

1( 

(4 
tt 
i( 
(( 
tt 
tl 
tt 
tt 


tt 
tt 
ft 
tt 
tt 
tt 
tt 
It 
tt 
tt 
tt 
tt 
tt 
tt 
tt 
tt 
tt 
tt 
tt 


Fine  eand  and  pebbles. 
Fine  and  coarse  sand. 
Coarse  sand  and  gravel. 


tt 
tt 


tt 
tt 


APPENDIX   III.— HYDROGRAPHIC   REPORT 


303 


SEDIMENT  ROLLED  ON  BOTTOM  OF  SAN  CARLOS  RIVER,  COSTA  RICA.— Continued. 


hei|;b^. 

Amt.  collected 
per  hr.  in  c.  c. 

Total  for  river 

Mean  for  month 

Total  cu. 

Date. 

In  cu.  yds.  per 
hour. 

in  cu.  yds.  per 
hour. 

yds.  per                Remarks 
month. 

DfC. 

16 

13.35 

62,680 

16.40 

ki 

23 

12.40 

23,070 

6.00 

15.10 

11,230 

Jan. 

3,  1899. 

13.80 

27,702 

7.30 

ti 

9 

12.50 

22,368 

5.a5 

It 

19 

13.20 

92,272 

24.10 

« 

(( 

23 

12.50 

64,704 

16.90 

•    •   • 

t( 

27 

12.20 

90,450 

23.65 

t( 

28 

12.15 

137,250 

35.90 

18.95 

14,100 

Feb. 

9 

11.69 

31,002 

8.10 

(( 

23 

13.55 

5,434 

1.40 

4.75 

3,190 

Mar. 

10 

12.15 

7,034 

1.85 

1    li 

• 

20 

11.40 

58,250 

15.25 

P" 

24 

11.20 

152,420 

39.  a5 

18.98 

14,120 

SEE 

HMENT  ROLLE 

3D  ON  BOTTOM  OF  RIO  SAI 

Total  for  river       TLr«on  fr»». 
i„eu.^>;ds.per       M-t^ 

lAPIQUI. 

Date. 

Gaffe 
height. 

Arat.  collected 
per  hour  in  c.  c. 

Total  for 

month                     Remarks. 
In  cu.  ydP. 

Sept. 

,     1,  1898. 

7.95 

11,000 

1.44 

Sediment  is   in  variably 

i( 

5 

8.22 

5,000 

.66 

composed  of  black  sand 

•tt 

« 

8.38 

5,000 

.66 

with  occasional  gravel. 

t( 

19 

8.79 

29,000 

3.80 

t( 

20 

8.70 

15,000 

1.96 

ti 

26 

9.46 

15,750 

2.05 

1.76 

1,270 

Oct. 

4 

8.46 

16,500 

2.16 

it 

12 

10.50 

22,500 

2.95 

tt 

18 

11.65 

49,300 

6.45 

tt 

20 

11.50 

41,700 

5.46 

it 

21 

10.65 

32,500 

4.26 

•   ••••• 

it 

25 

10.50 

26,000 

3.41 

tt 

28 

10.10 

25,250 

3.31 

4.00 

2,976 

Nov. 

1 

9.23 

32,000 

4.20 

(i 

2 

8.75 

29,000 

3.80 

tt 

3 

8.55 

21,000 

2.70 

tt 

4 

9.30 

45,600 

5.95 

tt 

5 

8.90 

26,000 

3.70 

it 

11 

12.10 

42,000 

5.50 

tt 

12 

11.20 

22,000 

2.90 

tt 

22 

11.00 

148,000 

19.40 

it 

28 

10.30 

76,000 

10.00 

tt 

24 

9.90 

31,000 

4.05 

tt 

26 

9.80 

57,000 

7.50 

tt 

28 

10.05 

22,500 

3.00 

6.06 

4,860 

Dec. 

1 

9.70 

88.000 

11.50 

Sand. 

tt 

3 

11.30 

188,000 

24.60 

• 

tt 

tt 

5 

10.80 

122,000 

16.00 

^ tt 

it 

12 

11.95 

69,400 

9.10 

, tt 

tt 

14 

10.05 

55,000 

7.20 

tt 

tt 

15 

9,48 

79,000 

10.80 

(t 

ti 

22 

7.98 

51,000 

6.60 

12.20 

9,080        '» 

Jan. 

2,  1899. 

12.14 

22,500 

2.90 

tt 

tt 

4 

8.41 

48,000 

6.80 

^ tt 

if 

10 

8.34 

76,000 

9.90 

it 

ti 

X  1  •  •  •      •  • 

10.70 

25,500 

3.30 

tt 

tt 

18 

9.76 

33,500 

4.40 

Coarse  sand  and  gravel. 

tt 

19 

10.16 

86,000 

11.20 

tt          tt       tt         tt 

tt 

23 

8.39 

40,000 

5.20 

tt          ti       it         tt 

ti 

24 

8.46 

84,000 

4.40 

Fine  sand  and  some  gravel. 

tt 

26 

8,30 

80,000 

3.90 

5.72 

4,260    Sand. 

Feb. 

2 

7.42 

10,500 

1.40 

tt 

tt 

6 

7.72 

24,500 

3.20 

ti 

tt 

7 

7.90 

25,000 

8.80 

it 

tt 

15 

9.58 

24,000 

3.10 

fi 

tt 

18 

8.46 

17,000 

2.20 

it 

it 

22 

9.50 

42,500 

5.60 

it 

tt 

23 

9.84 

11,500 

1.50 

tt 

It 

28 

9.36 

28,000 

3.00 

2.91 

1,960        " 

304 


NICARAGUA  CANAL  COMMISSION 


Temperature  and  Relative  Humidity. 

The  temperature  of  Nicaragua  is  remarkably 
uniform.  AVhile  some  of  the  higher  mountain 
regions  have  a  rather  cool  climate,  there  is  never 
any  frost,  and  in  general  it  may  be  said  that  in 
the  habitable  region  of  the  republic  the  tem- 
perature seldom  exceeds  90  degrees  Fahrenheit 
or  falls  below  70,  and  in  any  given  locality  the 
annual  fluctuation  is  usually  still  less. 


The  relative  humidity  is  high  in  all  of  the  uni- 
formly high  temperatures  excepting  during  the 
dry  season  on  the  west  side  of  the  isthmus. 

Obeen'ations  of  wet  and  dry  bulb  thermom- 
eters were  carried  on  at  the  station  on  the  Tlio 
Grande,  at  Las  I-.ajas,  Rio  Viejo,  Fort  San 
Carlos,  Sabalos,  Rio  San  Carlos,  Ochoa,  Deseado 
and  at  Greytown,  and  the  results  are  given  in 
the  following  tables: 


TEMPERATURE  AND  RELATIVE  HUMIDITY  AT  BRITO  AND  TOLA  STATIONS,  1898. 


January. 


Fkbuuauy. 


March. 


April. 


Day. 


-^ — 


Mean    Mean    Relative 
temp,    t— t'.  humidity. 


Mean     Mean    Relative 
temp,      t— f.  humidity. 


Mean      Mean    Relative 
temp.      t— t'.  humidity. 


Mean       Mean    Relative 
temp.       t— t .  humidity. 


1. 
•) 

3. 
4. 
5. 

6. 

rr 

I  . 

8. 

9. 

10. 

11. 

12. 
13. 
14. 
15. 

16. 
17. 
18. 
19. 
20. 

21. 
22. 
23. 
24. 
25. 

26. 
27. 
28. 
29. 
30. 
31. 


79 

4.5 

81 

79 

5.5 

77 

78 

3.5 

85 

80 

6.5 

74 

80 

7.0 

72 

81 

7.5 

70 

79 

7.5 

70 

80 

7.5 

70 

80 
80 
78 
80 
79 

81 
80 
80 
79 
80 

81 
81 
80 
80 
80 

81 
80 
81 

N2 
81 

82 
82 
80 
81 
81 

81 
81 
82 


7.0 
7.5 
7.5 
7.5 
7.5 

10.5 
8.5 
7.5 
6.5 
6.5 

7.5 
7.0 
7.5 

8.0 
8.0 

7.5 
7.5 
7.5 
7.5 

7.0 

7.0 
8.5 
7.5 
8.0 
7.0 

8.5 
8.0 
9.5 


72 

70 
70 
70 
70 

60 
66 
70 
74 

78 

70 
72 
70 
68 
68 

70 
70 
70 
70 
72 

72 
67 
70 
68 
72 

66 
68 
64 


•   •   •    • 


80 
81 
84 
84 
83 

83 
81 
81 
81 


;2 


83 
82 
83 
83 
84 

88 
84 
79 
82 
83 

83 
84 

82 
80 
82 

83 

84 
85 
84 
82 
83 


8.0 
7.0 
8.0 
8.0 
8.5 

8.5 
6.0 
7.5 
9.5 

8.5 

8.5 
7.5 
8.5 
8.0 

8.5 

8.5 
9.0 
5.5 
8.5 
9.5 

8.5 
9.5 
8.0 
3.5 
6.5 

5.5 
8.0 
7.5 
7.5 
6.0 
4.5 


68 
73 
69 
69 
67 

67 
76 
70 
63 
67 

67 
71 
67 
69 
67 

67 
66 
78 
66 
64 

67 
64 
69 
86 
74 

78 
69 

71 
71 

76 

82 


83 

84 
84 
84 
85 

84 
85 
86 
86 
86 

84 
82 
83 
83 

82 

82 
82 
83 
83 
83 

81 
82 
83 
84 
83 

82 
83 
84 
84 
82 


4.0 
6.5 
8.0 
6.5 
5.5 

6.5 

9.5 

12.0 

10.0 

10.5 

7.5 
7.0 
8.5 
7.0 
7.5 

7.5 
5.5 
7.0 
7.5 
6.0 

4.5 
6.0 
7.5 
8.0 
5.5 

6.5 
7.5 
7.5 
7.5 
5.5 


84 
75 
69 
75 

78 

.  75 
65 
57 
63 
62 

71 
72 
68 
73 
71 

71 

78 
73 
71 
76 

82 
76 
71 
69 
78 

74 
71 
71 

71 
78 


»* 


APPENDIX   III.— HYDROGRAPHIC   REPORT 


305 


TEMPERATURE  AND  RELATIVE  HUMIDITY  AT  BRITO  AND  TOLA  STATIONS.  1898. 


May 

■ 

June. 

July. 

1 

AUOUST. 

Day. 

r 

Mean 

Mean 

Relative 

Mean 

Mean 

Relative 

Mean 

Mean 

Relative 

Mean 

Mean 

Relative 

temp. 

t-t'. 

humidity. 

tomi>. 

t-t. 

humidity. 

temp. 

t-t'. 

humidity. 

temp. 

t-t'. 

humidity. 

1 

86 

9.0 

67 

81 

2.0 

92 

76 

0.5 

98 

79 

2.5 

89 

2 

84 

6.5 

75 

81 

2.5 

90 

78 

1.5 

94 

78 

2.5 

89 

8 

84 

7.5 

71 

81 

2.5 

90. 

78 

1.5 

94 

80 

2.5 

89 

4 

85 

5.5 

78 

81 

3.0 

88 

79 

2.0 

91 

78 

1.5 

94 

5 

80 

3.5 

86 

82 

2.5 

90 

80 

3.5 

85 

79 

1.5 

94 

6 

85 

4.5 

82 

82 

3.0 

88 

80 

2.5 

89 

81 

1.5 

94 

7 

86 

4.5 

82 

79 

0.5 

98 

78 

0.5 

98 

81 

3.0 

88 

8 

87 

5.5 

78 

82 

2.5 

90 

78 

2.5 

89 

80 

3.0 

87 

V,    .    .         .    . 

86 

5.0 

81 

82 

2.5 

90 

78 

1.0 

96 

80 

3.5 

85 

10 

86 

1.0 

96 

81 

2.0 

92 

77 

0.5 

98 

81 

2.0 

91 

11 

S2 

0.5 

98 

83 

4.0 

84 

78 

2.0 

92 

81 

2.5 

90 

12 

85 

1.5 

94 

83 

8.0 

69 

78 

0.5 

98 

78 

2.5 

89 

13 

85 

0.5 

98 

•    •   •   ■ 

•   •   • 

•   •   • 

79 

1.0 

96 

78 

2.0 

91 

14 

86 

1.0 

96 

80 

3.5 

85 

80 

1.5 

94 

76 

1.0 

96 

15 

85 

1.0 

96 

•   •   •   • 

•   •   •   • 

•    •   •    • 

80 

2.5 

89 

78 

2.0 

91 

16 

83 

3.0 

88 

•   •   •   • 

•   •   •   • 

•    •   •    • 

76 

0.5 

98 

79 

2.0 

91 

17 

84 

4.0 

84 

78 

1.0 

96 

79 

0.5 

98 

79 

2.5 

89 

18 

H-J 

4.0 

84 

78 

1.0 

96 

80 

2.0 

(»2 

78 

2.0 

91 

H» 

82 

2.5 

90 

78 

0.5 

98 

78 

3.0 

87 

80 

2.0 

92 

20 

80 

3.0 

87 

79 

0.5 

98 

78 

2.0 

91 

80 

2.0 

92 

21 

80 

3.0 

87 

78 

1.0 

96 

79 

2.5 

89 

78 

1.5 

94 

22 

74 

0.5 

98 

76 

0.5 

98 

79 

2.0 

91 

79 

1.5 

94 

28 

77 

1.0 

96 

78 

1.5 

94 

80 

3.0 

87 

80 

2.5 

89 

24 

1 1 

1.5 

94 

77 

1.0 

W 

79 

2.0 

91 

79 

1.5 

94 

25 

78 

3.5 

85 

79 

1.5 

94 

80 

2.5 

89 

79 

1.0 

96 

26 

78 

1.5 

94 

79 

1.5 

94 

78 

2.0 

91 

79 

2.0 

91 

27 

81 

2.0 

92 

76 

0.5 

98 

77 

1.0 

96 

79 

1.5 

94 

2S 

81 

1.0 

96 

75 

0.0 

100 

78 

1.5 

94 

78 

1.5 

$H 

29 

81 

2.0 

92 

78 

2.0 

91 

80 

2.5 

89 

78 

1.5 

94 

80 

82 

1.5 

94 

80 

2.5 

89 

76 

1.0 

96 

81 

2.5 

90 

81 

82 

2.5 

90 

•   •   •   • 

•   •   •  • 

•   •   •   • 

78 

1.5 

94 

80 

2.0 

92 

TEMPERATURE  AND   RELATIVE  HUMIDITY  AT  BRITO  AND  TOLA  STATIONS,  1898. 


Day 


1. 
2, 
3. 

4. 
5. 

6. 
7. 
8 
9. 
10. 

11. 
12. 
18. 
14. 
15. 


September. 

OCTOBEK. 

Mean 

Moan 

Relative 

Mean 

Mean 

Relative 

Temp. 

t— t'. 

humidity. 

Temp. 

t-t'. 

humidity. 

78 

8.0 

87 

80 

3.5 

85 

80 

2.5 

89 

81 

3.5 

86 

80 

3.0 

87 

81 

3.0 

88 

81 

3.0 

88 

82 

3.0 

88 

79 

2.0 

91 

77 

1.0 

95 

79 

1.5 

94 

81 

3.5 

86 

80 

2.5 

89 

76 

0.5 

98 

80 

2.5 

89 

78 

1.0 

96 

80 

2.0 

92 

79 

1.5 

94 

76 

1.0 

95 

78 

2.0 

91 

79 

2.0 

91 

74 

1.0 

95 

79 

1.5 

94 

78 

10 

96 

76 

1.0 

95 

77 

1.0 

95 

76 

0.5 

98 

77 

1.0 

95 

79 

1.5 

94 

78 

2.5 

89 

20 


306 


NICARAGUA  CANAL  COMMISSION 


TEMPERATURE  AND  RELATIVE  HUMIDITY  AT  BRITO  AND  TOLA  STATIONS,  1898.— Continued. 


Day. 


Septembek. 

Mean 

Mean 

Relative 

Temp. 

t-t'. 

humidity. 

79 

1.0 

96 

80 

1.5 

94 

81 

2.0 

92 

80 

8.0 

87 

70 

1.0 

95 

76 

1.5 

93 

78 

1.0 

96 

78 

0.5 

98 

79 

1.5 

94 

78 

1.5 

93 

76 

0.5 

98 

79 

1.0 

96 

80 

1.5 

94 

80 

1.5 

94 

84 

2.5 

90 

October. 


Mean 
Temp. 

Mean 
t-t. 

Relative 
humidity. 

78 

1.5 

93 

76 

0.5 

98 

76 

0.5 

98 

78 

1.0 

96 

78 

0.5 

98 

79 

1.0 

96 

78 

0.0 

100 

80 

3.5 

85 

78 

2.5 

89 

78 

1.5 

98 

82 

2.5 

90 

78 

1.0 

96 

78 

2.0 

91 

78 

2.0 

91 

80 

1.5 

94 

79 

2.0 

91 

16 

17. 

18. 

19 

20, 

21. 

22. 

23. 

24 

25, 

26. 
27. 
28. 
29. 
80. 
81. 


TEMPERATURE  AND  RELATIVE  HUMIDITY  AT  BRITO  AND  TOLA  STATIONS.  1898. 


NOVBMBER. 

December. 

Day. 

Max. 

Min. 

Mean. 

Mean 
t-t'. 

Relative 
humidity. 

r 

Max. 

Min. 

Mean. 

Mean 
t-t'. 

Relative 
humidity. 

1 • 

83.0 

70.0 

76.5 

2.0 

91 

81.5 

75.9 

78.1 

3.1 

87 

2 

81.0 

74.5 

77.5 

2.5 

89 

84.0 

77.5 

80.8 

2.8 

88 

8 

83.0 

70.0 

77.0 

3.5 

85 

84.7 

78.0 

81.0 

2.6 

90 

4 

83.0 

70.0 

77.5 

2.0 

91 

84.9 

76.0 

79.4 

2.9 

87 

5 

84.0 

75.0 

80.0 

8.0 

87 

83.2 

78.3 

80.5 

5.4 

77 

6 

85.5 

74.5 

80.0 

2.5 

89 

81.0 

76.1 

78.9 

8.9 

83 

7 

84.0 

76.5 

80.0 

8.0 

87 

88.0 

76.8 

79.8 

4.9 

79 

8 

84.0 

76.0 

79.0 

2.5 

89 

82.8 

75.8 

78.1 

8.9 

9 

81.5 

75.5 

78.0 

1.0 

96 

82.3 

76.2 

78.8 

2.6 

89 

10 

83.0 

75.5 

79.0 

1.5 

94 

81.0 

76.0 

79.0 

5.3 

77 

11 

83.8 

75.5 

79.0 

0.5 

98 

82.5 

75.0 

79.1 

4.5 

81 

12 

82.0 

75.5 

78.0 

1.0 

96 

82.9 

75.3 

79.6 

4.7 

81 

18 

78.5 

74.0 

76.5 

2.0 

91 

82.2 

75.4 

79.1 

5.6 

77 

14 

82.5 

70.0 

79.0 

3.0 

87 

78.7 

75.2 

77.4 

3.7 

85 

15 

79.5 

75.0 

77.5 

2.0 

91 

82.3 

78.6 

80.8 

6.2 

75 

16 

82.5 

75.5 

77.0 

2.0 

91 

80.2 

75.3 

77.2 

3.5 

85 

17 

80.0 

76.0 

77.5 

2.5 

89 

79.0 

76.0 

78.0 

4.6 

81 

18 

82.5 

75.0 

79.0 

2.5 

89 

82.8 

75.1 

79.2 

4.7 

81 

19 

81.0 

75.5 

77.5 

2.5 

89 

82.0 

74.5 

77.8 

3.7 

85 

20 

77.0 

76.0 

76.0 

1.5 

93 

81.4 

69.1 

76.8 

3.8 

85 

21 

82.0 

75.0 

78.5 

3.5 

85 

81.7 

74.9 

78.6 

4.8 

81 

22 

82.5 

76.0 

78.5 

2.5 

89 

88.0 

69.7 

78.3 

4.9 

79 

23 

82.5 

74.5 

79.0 

8.0 

87 

88.0 

79.2 

82.4 

7.8 

70 

24 

82.8 

73.5 

78.5 

8.5 

85 

81.8 

74.9 

78.4 

6.2 

79 

25 

84.0 

75.0 

79.5 

3.5 

85 

81.0 

74.0 

78.0 

4.4 

81 

26 

82.0 

76.0 

78.0 

2.5 

89 

83.0 

73.8 

77.9 

4.8 

81 

27 

81.0 

75.5 

77.5 

2.0 

91 

79.8 

74.5 

76.9 

2.6 

89 

28 

81.0 

75.0 

77.0 

2.0 

91 

78.5 

71.0 

74.8 

1.2 

95 

29 

84.0 

76.0 

80.0 

4.0 

83 

79.6 

74.5 

77.5 

2.2 

91 

80 

82.5 

76.0 

79.5 

4.0 

83 

82.2 

78.4 

79.8 

4.2 

83 

81 

•   •   •   • 

•   •   •   • 

•  •   •   • 

•   •   •   • 

. . .  • 

83.0 

76.7 

79.2 

8.6 

85 

APPENDIX   III.— HYDROGRAPHIC   REPORT 


307 


TEMPERATURE  AND  RELATIVE  HUMIDITY  AT  LAS  LAJAS  STATION. 


Month. 


Tempbrature. 


Maximum.   Minimum.     Mean. 


Mean. 

relative 

humidity. 


Temperature. 


Maximum.   Minimum.       Mean. 


Mean 

relative 

humidity. 


1898. 
February 
March  . . . 
April   ... 

May 

June  . . . . 

July 

August . . 


80 

84 

86 

91 

91 

85 

85 


75 
75 
77 
73 
73 
74 
74 


77.7 
79.5 

80.8 
82.1 
81.4 
79.7 
80.7 


81.1 
79.3 
79.1 
83.0 
84.8 
80. 6 
87.0 


September 85 

October 

November  ....  86 

December 83 

1899. 

January 82 

February 84 

March 86 


73 
73 

75 
70 
75 


79.4 

•   • 

79.3 
78.3 

78.5 

78.9 
80.6 


90.4 

•   • 

89.7 
91.1 

85.1 
85.1 
83.0 


TEMPERATURE  AND  RELATIVE  HUMIDITY  AT  LAS  LAJAS  STATION,  1898. 

Readings  7  A.  M.,  1  P.  M.  and  6  P.  M. 


February. 

March. 

Day. 

Max. 

MiTi           \fA«n           Mean        Relative 
MIn.          Mean.           ^^,        humidity. 

Max. 

Min. 

Mean. 

Mean 
t-t' 

Relative 
humidity. 

1 

•   •   •   • 

■   •   • 

79 

78 

78 

4.5 

81 

2 

•   •   •   • 

■   •  • 

80 

75 

78 

3.0 

87 

8 

•   •   •   •                       1 

>   •  • 

82 

76 

79 

3.5 

85 

4 

■  •   •  • 

•   •   i 

84 

79 

81 

4.5 

81 

5 

•   •  •   •                       ■ 

»   •    • 

83 

79 

80 

4.5 

81 

6 

•   •   •   •                       « 

k     •     •     4 

81 

78 

SO 

5.0 

79 

7 

•    •    •    •                               i 

1     •     • 

80 

77 

79 

4.5 

81 

8 

«    •    •    •                                < 

B     •     • 

81 

76 

79 

4.5 

81 

9 

•    •    •    • 

1     •     •     « 

81 

76 

79 

5.0 

79 

10 

•    •    •    • 

>     •     •    « 

80 

76 

78 

4.5 

81 

11 

•    •    •    • 

•     •     « 

82 

77 

80 

4.5 

81 

12 

•    •    •    • 

k     •     •     1 

83 

77 

80 

4.5 

81 

18 

•    •    •    •                               ■ 

•     •     1 

78 

77 

78 

4.0 

83 

14 

•    •    •    •                                « 

»     •     ■     1 

84 

78 

81 

5.0 

80 

15   

80 

76 

78 

4.j 

)               81 

83 

77 

80 

5.5 

77 

16 

78 

76 

77 

4.C 

)               83 

82 

78 

80 

5.5 

77 

17 

80 

76 

78 

4.C 

)               83 

83 

77 

80 

6.0 

75 

18... 

79 

75 

78 

4.( 

)               83 

81 

77 

79 

5.5 

77 

19 

79 

76 

78 

(5.<. 

;             85 

81 

76 

79 

5.5 

77 

20 

80 

76 

78 

4.G 

1               83 

82 

76 

80 

5.5 

77 

21 

78 

76 

77 

4.5 

•               80 

83 

77 

80 

5.5 

77 

22 

77 

76 

77 

4.S 

80 

82 

78 

80 

6.0 

75 

23 

80 

75 

78 

4.5 

i               81 

81 

77 

79 

5.0 

79 

24 

80 

77 

79 

5.C 

)               79 

80 

78 

79 

3.0 

87 

25 

* 

•   •   • 

•   •  •   • 

•   •  •  •                         1 

k     •     •     4 

•  •  •  • 

82 

78 

79 

4.0 

83 

26 

79 

75 

78 

5.5 

77 

83 

77 

80 

6.5 

74 

27 

80 

75 

77 

4.0 

83 

79 

78 

78 

4.5 

81 

28 

78 

76 

77 

5.5 

76 

83 

77 

80 

5.5 

77 

29 

•  •   ■ 

•  •  •  •                       • 

•  •  •                          • 

•  •   • 

• 

82 

77 

80 

6.0 

75 

30 

•   •   • 

•   •  •  •                       • 

•   •   •                          • 

•  •  • 

83 

76 

80 

6.5 

74 

31 

■   •   • 

•   •   •   •                        * 

•   •   •                           • 

•   •   • 

« 

83 

77 

80 

5.5 

74 

308 


NICARAGUA  CANAL  COMMISSION 


TEMPERATURE  AND  RELATIVE  HUMIDITY  AT  LAS  LAJAS  STATION.  1898. 


Day. 

April. 

> 

May. 

r 

Max. 

Mill. 

Mean. 

Mean 
t-t'. 

Relative 
humidity. 

Max. 

Min. 

Mean. 

Mean 
t-t. 

Relative 
humidity. 

1 

83 

77 

80 

5.5 

77 

85 

81 

83 

5.5 

78 

2 

88 

77 

81 

6.0 

76 

85 

81 

83 

5.0 

80 

8 

84 

77 

80 

5.5 

77 

86 

80 

83 

5.5 

78 

4 

84 

78 

80 

4.5 

81 

87 

79 

83 

5.5 

78 

5   

79 

79 

79 

8.5 

85 

87 

81 

83 

5.5 

78 

ft 

84 

79 

81 

3.5 

86 

88 

79 

84 

5.0 

80 

7 

80 

80 

80 

5.0 

79 

88 

82 

85 

5.5 

78 

8 

85 

77 

80 

5.5 

77 

88 

82 

85 

.5.5 

78 

9 

83 

77 

81 

6.5 

74 

87 

82 

84 

6.0 

77 

10 

81 

77 

7\» 

4.5 

81 

89 

81 

84 

6.0 

77 

11 

83 

78 

80 

5.0 

79 

84 

80 

82 

4.0 

84 

12 

81 

77 

79 

4.0 

83 

91 

81 

86 

5.5 

79 

13 

84 

81 

82 

5.5 

78 

88 

82 

84 

6.0 

77 

14 

83 

78 

81 

5.0 

80 

88 

79 

83 

5.5 

78 

15 

84 

79 

81 

6.0 

76 

82 

81 

♦81 

4.0 

84 

16 

83 

79 

81 

5.5 

78 

84 

81 

82 

4.5 

82 

17 

80 

79 

80 

4.5 

81 

87 

79 

84 

5.5 

78 

18 

84 

79 

81 

5.0 

80 

83 

78 

81 

3.0 

8S 

19 

83 

79 

81 

5.5 

78 

81 

80 

80 

3.0 

87 

20 

84 

80 

82 

5.5 

78 

80 

77 

81 

2.5 

90 

21 

84 

80 

82 

6.5 

74 

80 

78 

♦79 

2.0 

91 

22 

84 

79 

81 

5.0 

80 

76 

73 

*74 

0.5 

98 

23 

83 

79 

81 

4.0 

84 

76 

75 

75 

0.5 

98 

24 

85 

80 

83 

5.0 

80 

82 

75 

78 

2.0 

91 

25 

86 

79 

83 

6.5 

75 

82 

75 

78 

2.0 

91 

26 

85 

78 

81 

5.5 

78 

85 

77 

80 

4.0 

83 

27 

85 

80 

82 

5.0 

80 

89 

80 

84 

4.0 

84 

28 

83 

79 

81 

5.5 

78 

86 

81 

85 

4.0 

84 

29 

84 

80 

82 

5.0 

80 

88 

80 

Ki 

3.5 

86 

30 

82 

78 

80 

5.0 

79 

88 

82 

84 

5.0 

80 

81 

•                        •   •   •   • 

•    •    •    • 

•   •   •   • 

•   •   •   • 

• .  • . 

84 

83 

*83 

5.5 

78 

TEMPERATURE  AND  RELATIVE  HUMIDITY  AT  LAS  LAJAS  STATION,  1898. 


Day. 

June. 

July. 

f 

N 

t 

Max. 

Min. 

Mean. 

Mean 
t-t'. 

Relative 
humidity. 

Max. 

Min. 

Moan. 

Mean 
t-t'. 

3.5 

Relative 
humidity. 

1 

87 

83 

84 

5.5 

78 

80 

80 

♦SO 

85 

2 

87 

81 

*84 

5.5 

78 

82 

75 

78 

3.0 

87 

8 

87 

83 

85 

6.5 

75 

81 

78 

79 

2.5 

89 

4 

87 

80 

83 

5.5 

78 

80 

79 

80 

3.5 

85 

5 

88 

83 

85 

6.0 

77 

83 

79 

80 

4.0 

83 

6 

91 

83 

87 

6.0 

77 

84 

80 

81 

4.5 

82 

7 

82 

78 

81 

3.0 

88 

83 

79 

81 

3.0 

88 

8 

•   • 

•   • 

•   • 

•   •   • 

•   • 

83 

80 

81 

4.5 

82 

9 

91 

81 

♦86 

4.5 

82 

79 

79 

♦79 

3.5 

85 

10 

88 

81 

84 

4.0 

84 

81 

75 

78 

1.5 

9.3 

11 

85 

81 

84 

5.0 

80 

83 

76 

80 

2.5 

89 

12 

82 

79 

•80 

2.5 

90 

85 

79 

82 

3.5 

86 

18 

84 

80 

82 

4.5 

82 

84 

78 

81 

3.0 

88 

14 

82 

78 

80 

6.5 

77 

84 

80 

82 

3.0 

88 

15 

84 

80 

82 

6.0 

80 

84 

80 

82 

4.5 

82 

♦  Only  two  readings. 


APPENDIX   III.— HYDROGRAPHIC   REPORT 


309 


TEMPERATURE  AND  RELATIVE  HUMIDITY  AT     LAS  LAJAS  STATION,  1898.— Continued. 


Day. 

JUNB. 

July. 

f"' 

-» 

r' 

^^ 

Max. 

Min. 

Mean. 

Mftan 
t-t. 

Relative 
humidity. 

Max. 

Min. 

Mean. 

Mean 
t-t'. 

Relative 
humidity. 

16 

84 

80 

83 

4.5 

82 

84 

80 

81 

8.5 

86 

17 

81 

78 

79 

1.0 

96 

82 

79 

80 

2.0 

92 

18 

84 

76 

80 

1.5 

94 

84 

80 

81 

4.0 

84 

19 

85 

76 

81 

2.0 

92 

80 

79 

80 

4.0 

83 

20 

85 

77 

81 

3.0 

88 

79 

77 

78 

3.5 

85 

21 

83 

75 

79 

2.0 

91 

81 

76 

78 

3.0 

87 

22 

81 

75 

77 

1.0 

95 

80 

78 

79 

3.0 

87 

23 

85 

81 

82 

4.0 

84 

«   • 

•  • 

•  • 

•   •   • 

•   • 

24 

84 

79 

81 

4.5 

82 

81 

81 

♦81 

3.5 

86 

25 

84 

80 

80 

5.0 

79 

80 

79 

80 

3.0 

87 

26 

84 

76 

80 

3.0 

87 

78 

77 

78 

2.0 

91 

27 

81 

74 

77 

1.0 

95 

80 

74 

77 

4.0 

83 

28 

76 

73 

75 

0.5 

98 

79 

78 

78 

8.5 

85 

29 

82 

78 

77 

4.0 

83 

82 

80 

80 

1.5 

94 

80 

82 

79 

81 

8.5 

86 

78 

74 

7(i 

3.0 

87 

31 

1   •                                •   • 

•   • 

•   • 

•   •   • 

. . 

83 

78 

81 

3.0 

88 

TEMPERATURE  AND  RELATIVE  HUMIDITY  AT  LAS  LAJAS  STATION,  1898. 


August. 

8RPTEMBBR. 

Day. 

Max. 

Min. 

Mean. 

Mean 
t-t'. 

Relative 
humidity. 

r 

Max. 

Min. 

Mean. 

Mean 
t-t'. 

Relative 
humidity. 

1 

83 

70 

80 

3.0 

87 

84 

81 

82 

4.0 

84 

2 

81 

78 

79 

3.5 

85 

82 

80 

81 

4.0 

84 

3 

82 

79 

80 

3.0 

87 

84 

80 

81 

4.0 

84 

4 

81 

78 

80 

3.0 

87 

82 

76 

80 

2.5 

89 

5 

84 

79 

81 

3,0 

88 

•  •   •   • 

•   •   •   • 

•   •   •   • 

•   •   •   • 

•    •   •   • 

6 

82 

76 

80 

2.5 

89 

84 

82 

♦83 

4.0 

84 

7 

82 

80 

81 

3.5 

86 

85 

81 

82 

4.0 

84 

8 

83 

80 

82 

4.0 

84 

84 

79 

81 

4.0 

84 

9 

84 

79 

81 

3.5 

86 

81 

78 

80 

3.0 

87 

10 

82 

80 

81 

4.0 

84 

80 

73 

77 

1.5 

93 

11 

85 

79 

82 

3.5 

86 

82 

76 

78 

2.0 

91 

12 

81 

79 

80 

4.0 

83 

82 

77 

80 

2.5 

89 

13 

83 

75 

79 

2,5 

89 

77 

74 

76 

0.5 

98 

14 

79 

76 

78 

2.0 

91 

78 

74 

76 

0.5 

98 

15 

83 

76 

80 

2.5 

89 

83 

78 

80 

2.0 

90 

16 

83 

80 

81 

3.0 

88 

82 

76 

79 

3.0 

87 

17 

83 

79 

81 

3.0 

88 

85 

76 

81 

8.5 

86 

18 

83 

79 

82 

4.0 

84 

84 

81 

83 

4.0 

84 

19 

84 

76 

81 

3.5 

86 

•   •   •   • 

•   •   • 

•    •   •   • 

•   •   •   t 

•   •   •   • 

20 

84 

80 

82 

3.5 

.       86 

79 

74 

♦76 

2.0 

91 

21 

80 

74 

78 

2.0 

91 

80 

73 

77 

1.5 

93 

22 

84 

80 

82 

4.5 

82 

80 

76 

78 

1.5 

93 

23 

85 

81 

83 

4.0 

84 

80 

77 

78 

1.0 

96 

24 

84 

80 

82 

4.0 

84 

84 

77 

80 

2.0 

92 

25 

84 

81 

82 

3.0 

88 

83 

76 

80 

2.0 

92 

26 

85 

77 

82 

3.0 

88 

78 

76 

77 

1.0 

95 

27 

83 

78 

80 

2.5 

89 

80 

76 

77 

0.5 

98 

28 

84 

75 

80 

3.0 

87 

80 

76 

78 

1.5 

93 

29 

82 

76 

80 

2.0 

i)2 

85 

75 

80 

2.0 

92 

30 

84 

75 

80 

3.0 

87 

85 

78 

81 

2.5 

90 

31 

Ml 

80 

81 

2.5 

90 

•    •   •   • 

•    •    ■    ■ 

•   •   •   • 

•   •   •   • 

•    •   • 

♦  Only  two  readings. 


310 


NICARAGUA   CANAL  COMMISSION 


TEMPERATURE  AND  RELATIVE  HUMIDITY  AT  LAS  LAJAS  STATION,  1898. 


Day. 

October. 

• 

November. 

r — 

■  > 

r 

-» 

Max. 

Mill. 

Mean.         ^^J9 

Relative 
bumidity. 

Max. 

Mill. 

Mean. 

Mean 
t-t.' 

Relative 
humidity. 

1 

•   •   •   • 

•    •   •   • 

•   •    ■   • 

86.0 

77.0 

80.5 

4.5 

81.5 

2 

•   •   •   • 

•    •   •   • 

•   •   •   • 

83.5 

75.0 

78.5 

3.5 

85.0 

3 

•   •  •  • 

•   f   •   • 

•  •   •   • 

83.5 

74.5 

78.5 

3.0 

87.0 

4 

•   •   •   • 

•    •   •    • 

81.1 

78.2 

80.0 

3.0 

87.0 

5 

•   •   •  • 

•    •   • 

82.5 

78.5 

80.5 

3.5 

85.5 

6 

•   •   •   • 

•   •   •   • 

82.0 

80.0 

81.0 

3.5 

86.0 

7 

■   •   •   • 

•   •   •   •                      < 

82.5 

80.0 

81.5 

5.0 

80.0 

8 

•   •   •   • 

•   •   •   •                      * 

82.0 

79.0 

80.5 

3.0 

87.5 

« 

•   •  •  • 

•   •   •   • 

79.0 

77.0 

78. 0 

1.0 

96.0 

10 

•   •   •   ■ 

.... 

82.0 

79.2 

80.0 

1.5 

94.0 

11 

•    •   *   * 

•   •   •   •                      ■ 

82.5 

78.0 

80.0 

0.5 

98.0 

12 

•    •   •   • 

•   •   •   • 

82.1 

77.0 

79.5 

1.0 

96.0 

13 

•   •   •   • 

•   •   •    • 

79.2 

77.5 

78.5 

0.5 

98.0 

14 

•   •   •   • 

•    •   •   • 

80.1 

78.1 

71>.5 

1.5 

94.0 

15 

•   •   •   ■ 

•    •   •   • 

81.5 

78.8 

80.0 

2.0 

92.0 

16 

•    •   •   • 

•    •   •   •                      • 

81.2 

77.0 

79.0 

2.5 

89.0 

17 

•   •   •   • 

•   •   •   •                      4 

80.0 

77.5 

79.0 

0.5 

79.0 

18 

•   •   •   • 

•    •   •   • 

80.3 

73.2 

78.0 

1.0 

96.0 

19 

•    •   •   • 

•   •   •   •                      1 

80.7 

77.5 

7i».0 

3.0 

87.0 

20 

•    •   •   • 

•    •   •   • 

80.0 

76.5 

78.0 

1.5 

93.0 

21 

•    •   •   • 

•   •   •   • 

79.2 

76.9 

78.5 

2.0 

91.0 

22 

•   •   •   • 

■   •   •   • 

81.0 

78.8 

79.5 

2.5 

89.8 

23 

•   •   •    • 

■   •   •    ■                       1 

81.0 

77.6 

80.0 

2.0 

92.0 

24 

•   •   •    • 

•   •   •   • 

81.0 

77.0 

79.5 

3.0 

87.0 

25 

•   •   •   • 

•   •   ■    >                       « 

81.0 

77.0 

79.5 

1.3 

94.0 

26 

77.8 

•   •   •   ■                      1 

81.2 

77.0 

79.5 

1.5 

94.0 

27 

83.0 

78.0 

80.5 

3.5 

85.5 

80.6 

75.1 

78.0 

2.5 

89.0 

28 

81.0 

74.0 

77.5 

1.5 

93.0 

78.0 

75.2 

76.5 

2.5 

8«.).0 

29 

84.5 

77.0 

80.0 

3.0 

87.0 

80.5 

78.3 

79.5 

3.0 

87.0 

30 

83.0 

77.0 

79.0 

2.0 

91.0 

81.5 

77.4 

79.0 

3.0 

87.0 

31 

85.0 

79.0 

82.0 

3.0 

88.0 

•   •   •   • 

•   •        • 

■   •   •   • 

.  •  •  • 

•   •  «   • 

TEMPERATURE  AND  RELATIVE  HUMIDITY  AT  LAS  LAJAS  STATION,  1898-9. 


Day 


1. 
») 

3. 

4 

5. 

6. 

i . 

8. 

9. 

10. 

11- 
12. 
13. 
14. 
15. 


December,  1888. 


Max. 


Min. 


Mean. 


Mean      Relative 
t— t'.      humidity. 


•    •    •    • 

77.0 

77.4 

3.20 

87 

81.2 

78.6 

80.2 

2.06 

92 

83.0 

78.9 

80.8 

2.43 

90 

82.8 

79.1 

81.2 

3.53 

86 

82.6 

77.8 

78.5 

4.10 

83 

80.1 

76.3 

77.4 

2.76 

89 

•   •  •   • 

77.4 

•   •   •   • 

•   •   •   • 

•   •   •   • 

80.5 

79.0 

78.6 

3.86 

83 

79.2 

77.6 

79.8 

2.26 

92 

80.5 

79.3 

79.2 

4.63 

81 

82.0 

76.5 

78.8 

3.23 

87 

•   •   •   • 

78.2 

•  • .  • 

•   •   •   • 

•   •   •   « 

80.2 

76.8 

78.0 

2.90 

87 

79.2 

76.8 

78.9 

3.50 

85 

80.3 

75.2 

76.9 

3.53 

85 

Max. 


January,  1899. 

* 


MIn. 


81.5 


78.0 


Mean. 


Mean      Relative 
t— t'.     humidity. 


78.5 

77.0 

77.8 

2.0 

91 

79.5 

76.5 

78.0 

3.0 

87 

79.0 

77.0 

77.5 

3.5 

8S 

80.0 

77.0 

78.5 

4.0 

83 

80.5 

76.0 

78.5 

4.5 

81 

80.5 

76.0 

78.5 

8.5 

85 

80.0 

75.5 

77.0 

3.0 

87 

80.5 

77.0 

78.5 

3.0 

87 

81.0 

76.5 

78.0 

4.0 

83 

81.0 

77.0 

79.0 

3.0 

87 

80.0 


4.5 


81 


APPENDIX   III.— HYDROGRAPHIC   REPORT 


311 


TEMPERATURE  AND  RELATIVE  HUMIDITY  AT     LAS  LAJAS  STATION,  1898-9.— Continued. 


Day. 

Deoembbr,  1896. 

January, 

4 

1899. 

'■" 

1 

f — 

Max. 

Min. 

Mean. 

Mean 
t-t. 

Relative 
humidity. 

Max. 

Min. 

Mean. 

Mean 
t-t'. 

Relative 
humidity. 

10 

i  4.4 

76.4 

76.1 

2.96 

.S7 

79.5 

76.5 

78.0 

2.5 

89 

17 

•    ■    •    • 

75.0 

•   •   •   • 

•   •   •   • 

•   «   •   • 

81.0 

76.0 

78.5 

3.0 

87 

18 

•    •    •    • 

76.2 

•   •   •   • 

•    •   •   • 

•    •   •   • 

80.5 

76.0 

78.5 

3.0 

87 

19 

79.8 

76.4 

78.3 

3.40 

85 

80.5 

76.0 

79,0 

5.0 

79 

20 

81.4 

76,4 

78.6 

2.53 

89 

79.5 

75.5 

77.5 

4.0 

83 

21 

79.2 

76.3 

77.6 

2.90 

87 

79.5 

75.5 

77.5 

8.0 

87 

22 

79.7 

74.7 

77.2 

1.50 

93 

79.0 

75.0 

77.5 

3.5 

85 

23 

80.0 

76.4 

78.7 

2.36 

89 

80.5 

75.0 

78.0 

8.0 

87 

24 

•   •  •   • 

76.0 

•   •   •   • 

•   •   •   • 

«   •  •   • 

•   •   •   • 

•   •   •   • 

•   •   •   • 

.... 

•   •   •   • 

25 

•   •   •   • 

•    •  •   • 

•    •   •   • 

•   «   ■   • 

•   •   •   • 

82.0 

78.0 

80.0 

4.0 

83 

26 

•   •   •   « 

•    •   «   • 

•   •   •   • 

•  •  •   • 

•   •   •  • 

81.0 

78.0 

79.5 

8.5 

85 

27 

•   •   •   • 

•   •   •   • 

•  •   •   • 

•   •   •   • 

•   •  •  • 

80.0 

76.5 

79.0 

4.0 

83 

28 

75.1 

73.5 

74.2 

1.00 

95 

81.0 

76.0 

78.0 

8.0 

87 

29 

80.0 

76.0 

78.3 

.  3.96 

83 

79.5 

77.0 

78.5 

3.5 

85 

80 

79.9 

76-2 

77.6 

2.20 

91 

80.5 

76.0 

79.0 

4.0 

83 

31 

7l».5 

76.9 

78.5 

2.63 

89 

•   •   •   « 

■   •   •   • 

•   •   •   • 

•   •  •   • 

•   •   •   • 

TEMPERATURE  AND  RELATIVE  HUMIDITY  AT  LAS  LAJAS  STATION,  1899. 


Frbruaky. 


I>ay. 


Max. 


Min. 


Mean. 


Mean        Relative 
t— t'.       humidity. 


March. 

Max. 

Min. 

Mean. 

Mc«n 

t-t'. 

Relative 
humidity. 

81.5 

76.0 

79.0 

3.5 

85 

82.5 

75.0 

79.5 

8.5 

85 

82.0 

76.0 

79.5 

3.5 

85 

82.0 

75.0 

79.0 

3.0 

87 

83.0 

77.0 

80.5 

4.0 

88 

1 

o 

M  .    .    .    .    . 

8 

4 

5 

6 

< 

8.    ... 

9 

10 

11 

12 

18 

14 

15 

16 

17. . . .'. 

18 

19 

20 

21 

22. .  .•. . 

23 

24 

25 

26 

27 

28 

29 

80 

81 


80.5 


"6.5 


78.5 


3.0 


87 


81.0 
81.0 
80.5 

76.0 
76.5 
76.5 

7t).0 
79.0 
78.5 

3.5 
8.5 
4.0 

85 
85 
88 

82.0 

76.0 

78.5 

3.0 

87 

•  •    •   ■ 

83.0 
81.0 

•  •   •   • 

•  ■   •   • 

•  •  •   • 

77.0 

•  •   •   • 

•  •   •   • 

•  •   •   • 

79.5 

•  •  •   • 

•  •   •   • 

•  •   •   • 

5.0 

•  •   •   • 

•  •  •   • 

•  •   •   • 

79 

•  •  •   • 

•  •   •   • 

80.0 
80.0 
75.2 

•  •   •   • 

•  •   •   • 

•  •   •   • 

77.0 
70.0 

■   •   •   • 

•  •   •   • 

•  •   •   « 

78.5 
74.0 

•  •   •   • 

•  •   •   • 

•  •   •   • 

5.5 
4.0 

•  •  •   • 

•  •   •   • 

•  •   •   • 

77 
82 

•  •   •   ■ 

80.0 
76.5 
82.0 
81.5 
84.0 

75.0 
75.5 
76.0 
76.0 
77.0 

78.5 
76.0 
79.0 
78.5 
80.5 

2.0 
2.0 
8.0 
4.0 
4.0 

91 
91 

87 
88 
84 

84.0 
82  5 
83.5 

76.0 
77.0 
77.0 

80.0 
80.0 
80.5 

8.0 
4.0 
4.0 

87 
83 
84 

•   •   •   • 

85.0 

•  •   •   • 

•  •   •   • 

•  •   •   • 

•  •   •   • 

•  V     •      • 

•  •   •   • 

•  •   •  • 

•  •  •   • 

84.0 
83.0 
81.5 

76.5 
78.0 
74.0 

81.0 
80.5 

78.5 

2.0 
8.0 
4.0 

92 

88 
83 

83.0 


81.5 
80.5 

82.0 
83.0 
82.5 
80.5 
84.0 

86.0 
84.5 
82.5 

84.0 

84.0 
84.5 
84.0 
82.5 
84.0 

85.0 
82.5 
84.5 
85.0 

•   •   •   ■ 

82.5 


77.0 

•  •   •   • 

•  •   •   • 

77.0 
78.0 

76.0 
76.0 
77.0 
78.5 
76.0 

79.0 
79.0 


78.0 

78.0 
78.5 
79.0 
78.5 


80.0 

78.5 
78.6 
78.0 

•   •   •   • 

80.0 


79.0 


79.5 
79.5 

79.5 
79.0 
79.0 
80.0 
80.5 

82.5 
81.0 


81.5 

81.5 
81.5 
81.5 
80.5 


82.5 
81.0 
82.5 
82.5 

•   •   •   • 

81.5 


4.0 


3.5 
3.5 

4.0 
3.5 
8.5 
3.0 
3.5 

8.5 
4.5 


4.5 

5.5 
5.0 
5.0 
4.5 


5.5 
5.0 
5.5 
5.0 

I  •  •   • 

8.5 


88 


85 
55 

83 
85 

85 
87 
86 

86 
82 


82 

78 
80 
80 
81 


78 
80 
78 
80 

'  •   • 

86 


312 


NICARAGUA  CANAL  COMMISSION 


TEMPERATURE  AND  RELATIVE  HUMIDITY  AT  RIO  VIBJO  STATION,  1898. 


Month. 


Temperature. 


Maximum. 


Minimum. 


Mean. 


Mean 
relative  humidity. 


February . . 

March 

April 

May 

June 

July    

August  .  . . 
September 


89 
97 
94 
96 
94 
89 
90 
89 


63 
63 
69 
71 
70 
70 
71 
70 


78.1 
78.8 
82.8 
83.3 
80.6 
78.8 
78.4 
78.0 


58.9 
59.1 
59.4 
71.0 
81.4 
79.6 
83.1 
86.3 


TEMPERATURE  AND  RELATIVE   HUMIDITY  AT   RIO  VIEJO  STATION,   1898. 


Day 


February. 


March. 


Max. 


Min. 


Mean. 


Mean 
t-t' 


Relative 
humidity. 


Max. 


Mln. 


Mean. 


Mean       Relative 
t— t'.     humidity. 


1 

3 

8 

4. 

5 

6. 

7. 

8. 

9. 

10. 

11. 
12. 
13. 
14. 
15. 

16. 
17. 
18. 
19. 
20. 

21. 
22. 
23. 
24. 
25. 

26. 
27. 
28. 
29. 
80. 
81. 


84 
85 
89 
88 

87 
89 
83 
87 
85 


86 
86 

87 

89 

88 
85 
85 
83 


89 


73 
66 
68 
70 

73 

71 
73 
71 

7i 


73 


66 


66 


69 


77.7 
75.7 
78.3 
78.3 

79.3 
79.7 
78.0 
79.0 
77.7 


79.3 


10 
11 
10 

7 

13 
10 
9 
13 
10 


68 

76.0 

10.5 

70 

79.0 

10 

70 

78.7 

10.5 

66 

78.8 

10 

70 

78  7 

10 

68 

77.3 

9.5 

68 

77.0 

9.5 

71 

77.0 

10.5 

13.5 


60 
56 
61 

71 

53 
61 
63 
53 
60 


57 
60 

58 

60 
60 
61 
61 
57 


48 


91 
93 
97 
86 
85 


68 
67 
06 
69 
73 


79 
81 
78 
79 
78 


11  0 
9.5 
6.6 
9.0 
9.0 


57 
63 
73 
64 
63 


88. 

^ 

76 

8.0 

66 

87 

71 

79 

13.0 

53 

87 

69 

79 

11.0 

57 

87 

70 

79 

11.5 

55 

93 

70 

81 

11.5 

56 

94 

69 

81 

11.0 

58 

•  • 

63 

•  •  •  • 

•  •  •  • 

•  •  •  • 

88 

•  •  •  • 

73 

•  •  •  • 

81 

•  •  •  • 

11.5 

•  •  •  • 

56 

89 

06 

79 

10.5 

58 

85 

68 

78 

9.5 

63 

87 

70 

79 

11.5 

55 

88 

73 

80 

10.5 

59 

83 

68 

75 

7.5 

68 

83 

70 

77 

9.5 

61 

89 

69 

79 

11.0 

57 

87 

70 

80 

10.5 

59 

84 

70 

77 

8.5 

65 

91 

69 

78 

10.0 

60 

87 

73 

78 

9.5 

63 

87 

71 

79 

13.5 

53 

86 

71 

79 

13.0 

53 

88 

73 

79 

11.0 

57 

87 

73 

80 

13.5 

52 

87 

7:^ 

80 

13.0 

51 

88 

70  ' 

79 

9.5 

63 

APPENDIX   III.— HYDROGRAPHIC   REPORT 


313 


TEMPERATURE  AND  RELA.TIVB  HUMIDITY  AT  RIO  VIEJO  STATION,  1898. 


Max. 

APRIIi. 

May. 

Day. 

Mln. 

Mean. 

Mean 
t— t'. 

Relative 
humidity. 

r    ' 

Max. 

Min. 

Mean. 

Mean 
t-t'. 

Relative 
humidity. 

1 

87 

•   •   •   • 

69 

•   •   •   • 

79 

t   •   •   • 

9.5 

•  •   •  • 

62 

•    •   •   • 

90 

88 

79 

77 

88 

82 

8.5 
9.5 

68 

2 

64 

8 

•  •   •   • 

•  •    •  • 

90 

•  •   •   • 

•  ■   •   • 

74 

•  •  •   • 

•  •   •   • 

82 

V      •     •      • 

•   •   •   • 

10.0 

•  •   •  • 

•  •   •   • 

62 

83 
92 
91 

78 
80 
77 

81 
85 
82 

9.5 
13.0 
10,0 

64 

4 

53 

62 

6 

S9 
88 

75 
75 

82 
82 

9.5 
11.5 

63 
57 

96 
90 

80 

82 

86 
85 

12.0 
10.5 

57 

7 

62 

8 

89 

71 

79 

10.5 

58 

98 

81 

86 

12.0 

57 

9 

•  •   •  • 

•  •   •   • 

•  •  •   • 

•  •   «   • 

•  •   •  • 

•  •   •   • 

•  •   •   • 

•  •   •  • 

•   •   •  • 

■   •  •  • 

92 
91 

81 

78 

85 
85 

11.5 
11.0 

58 

10. 

60 

11 

89 

72 

81 

11.0 

58 

95 

84 

89 

12.5 

57 

12 

90 

78 

82 

9.5 

63 

94 

80 

86 

11.5 

58 

18 

88 

69 

80 

9.5 

62 

93 

79 

85 

12.5 

55 

14 

98 

72 

85 

12.0 

56 

95 

80 

87 

14.5 

50 

15 

94 

86 
93 

72 

76 

78 

84 

82 
85 

11.5 

8.5 
9.5 

58 

67 
64 

96 

90 
90 

79 

79 

81 

86 

88 

84 

9.5 

8.5 
9.0 

65 

16 

68 

17 

66 

18 

90 

79 

84 

9.5 

64 

90 

77 

82 

0.5 

74 

19 :. 

90 

75 

88 

9.0 

66 

82 

73 

78 

2.5 

89 

20 

82 

92 
89 
91 
91 
90 

92 

79 

80 
70 
79 
74 
84 

88 

81 

84 
80 
84 
82 
87 

87 

8.0 

m 

12.0 
11.0 
13.0 
11.5 
15.5 

13.0 

68 

56 
57 
58 
56 
46 

54 

86 

85 
74 
77 
74 
88 

84 

74 

74 
71 
72 
72 
74 

78 

80 

80 
72 
74 
78 

78 

81 

3.5 

3.5 
1.0 
1.5 
1.0 
2.5 

4.5 

85 

21 

85 

22 

95 

23 

98 

24 

95 

25 

89 

26 

82 

27 

91 

81 

85 

12.5 

54 

91 

78 

84 

5.5 

78 

28 

98 

76 

88 

10.5 

60 

93 

75 

88 

5.0 

80 

29 

90 

81 

84 

12.0 

56 

92 

79 

84 

5.5 

78 

80 

89 

74 

82 

9.5 

64 

90 

76 

81 

5.5 

78 

31 

•    •  •   • 

•   •   •   • 

•   •   •   • 

•   •   •   • 

•   •   •   • 

91 

76 

82 

6.5 

74 

TEMPERATURE  AND  RELATIVE  HUMIDITY  AT  RIO  VIEJO  STATION,  1898. 


Day. 

June. 

July. 

Max. 

Min. 

Mean. 

Mean 
t-t'. 

Relative 
humidity. 

Max. 

Mln. 

Moan. 

Mean 
t-t'. 

Relative 
humidity, 

1 

89 
92 
92 
92 
91 

90 
•   94 
92 
91 
92 

87 
85 
85 
88 
88 

82 
80 
81 
79 

78 

72 
74 
80 
80 
77 

78 
75 
75 
78 
75 

85 
85 
85 
85 
84 

81 
84 
84 
84 
82 

82 
79 
80 
78 
81 

9.5 
6.5 
7.5 
7.0 
6.5 

4.5 
5.0 
5.5 
6.5 
4.5 

4.0 
4.0 
5.5 
7.5 
6.5 

64 
75 
72 
73 
75 

82 
80 
78 
75 
82 

84 
88 
77 
69 
74 

85 
88 
84 
80 
86 

86 
85 

85 

•  •   •   • 

•  •   •   • 

«   •   •   • 

85 
89 
82 
89 

75 
77 
76 
75 

78 

74 
70 
76 

•  ■   •   • 

•  •   «    • 

•  •   •    • 

77 
75 
75 
76 

79 
80 
79 

78 
81 

78 
77 
79 

•  •   •   • 

•  •   ■   • 

•  •   •   • 

80 
81 
78 
81 

8.0 
4.5 
5.5 
5.5 
7.5 

4,5 
4.5 

6.0 

•  •   •    • 

•  •   •   • 

•  •   •   • 

3.5 
4.5 
2.5 
5.0 

87 

2 

8 

81 
77 

4 

77 

5 

70 

6 

7 

8 

81 
80 
75 

9 

10 

•   •   •    • 

11 

12 

85 

18 

14 

15 

82 
89 
80 

314 


NICARAGUA  CANAL   COMMISSION 


TEMPERATURE  AND  RELATIVE  HUMIDITY  AT  RIO  VIEJO  STATION.  1898.— Continued. 


Day. 

June. 

July. 

Max. 

Min. 

Mean. 

Mean 
t-t. 

Relative 
humidity. 

Max. 

Min. 

Mean. 

Mean 
t-t. 

iielativo 
humidity. 

16 

92 

75 

82 

5.5 

78 

87 

77 

81 

5.5 

78 

17 

93 

78 

85 

5.0 

80 

88 

78 

82 

6.0 

70 

IS 

SO 

74 

77 

2.5 

S9 

80 

79 

SO 

6.5 

74 

19 

86 

73 

78 

1.5 

93 

86 

80 

6.5 

74 

20 

So 

74 

78 

2.0 

91 

SO 

73 

76 

3.0 

87 

21 

90 

73 
71 
75 

79 
79 
80 

2.0 
2.5 
3.0 

91 
89 

87 

83 
87 
S2 

74 
72 
73 

t  f 
SO 
77 

4.5 
5.0 
5.5 

80 

22 

89 

TV 

23 

86 

76 

24 

80 

72 

76 

2.0 

91 

S7 

77 

81 

6.5 

74 

25 

84 

72 

78 

78 
80 

3.5 
5.0 

85 
79 

87 
80 

77 

71 

80 

77 

6.5 
4.0 

74 

26 

S4 

8:5 

27 

87 

71 
70 

77 
74 

2.0 
2.0 

91 
91 

87 
78 

71 
70 

78 
73 

0.0 
2.5 

75 

28 

77 

88 

29 

83 

72 

78 

3.5 

85 

86 

73 

78 

4.5 

81 

30 

84 

73 

78 

5.5 

77 

79 

70 

75 

2.5 

89 

81 

•    •••                    •••• 

•   •   •   • 

•    •   •    • 

•   •   •   • 

•    •   •   ■ 

87 

75 

81 

5.5 

78 

TEMPERATURE  AND  RELATIVE  HUMIDITY  AT  RIO  VIEJO  STATION,  1898. 


AuausT. 


Skptembek. 


Day. 


Max. 


Min. 


Mean. 


Mean 
t-t'. 


Relative 
humidity. 


Max. 


Min. 


Mean. 


lean 

Relative 

,-t'. 

humidity. 

5.5 

t  t 

3.5 

85 

4.0 

88 

4.5 

81 

3.0 

87 

0.0 

•    ■    •    • 

2.5 

8» 

3.5 

85 

1. 

2. 
3. 
4. 
5. 

6. 
7. 
8. 
9. 
10. 

11. 
12. 
13. 
14. 
15. 

16. 
17, 
18. 
19. 
20. 

21. 
22. 
23. 
24. 
25. 

26. 
27. 
28. 
29. 
30. 
81 


80 
86 
84 
80 
83 


85 


83 

88 


85 
80 

86 
90 
79 

85 
87 
86 


To 
76 
72 
72 
73 


73 
5 


78 
77 


75 
72 
71 

72 
77 
77 


80 
78 
75 
76 


78 

79 
79 


80 
79 

79 
80 
75 
78 
81 
80 


3.5 
5.5 
4.0 
3.5 


8.5 


5.5 
4.5 

4.0 
2.5 
2.5 
4.0 
4.5 
5.5 


85 
77 
83 
85 


85 


4.0 

83 

2.5 

89 

•  • 

•  ■ 

•  «   •   • 

•  •   •   ■ 

i  i 

81 

83 
89 
89 
83 
81 
77 


85 
84 
82 

82 

78 

78 
80 
80 


77 
76 
78 
78 
76 


74 
73 
75 


80 
80 
79 
79 

77 


76 

78 


86 

73 

79 

3.5 

85 

83 

71 

76 

2.0 

91 

86 

70 

78 

4.0 

83 

84 

76 

80 

5.5 

77 

86 

74 

79 

5.5 

77 

88 

71 

78 

3.5 

85 

74 

71 

73 

0.5 

98 

83 

73 

77 

1.5 

93 

87 

73 

78 

2.0 

91 

84 

73 

78 

2.5 

80 

89 

75 

80 

3.5 

85 

89 

74 

80 

3.0 

87 

85 

74 

78 

2.5 

89 

80 

74 

77 

2.0 

91 

83 

73 

77 

2.5 

89 

APPENDIX   III.— HYDROGRAPHIC   REPORT 


315 


TEMPERATURE  AND  RELATIVE  HUMIDITY  AT  FORT  SAN  CARLOS   STATION. 


Tkmpekaturk. 

Mont**                                                -*■ 

Mean. 

Mean 

relative 
humidity 

k 

Month. 

Max. 
90. 

TEMPEKi 

Mir 
74 

I.TURE. 

Mean 
relative 

Max. 

Min. 

1. 

Moan. 
79.8 

humidity. 

1898. 

October. . . . 

8S.8 

Marcb 

88. 

70. 

78.1 

75.8 

November. . 

88.5                72 

77.9 

90.1 

April 

88.5 

70.5 

78.5 

79.1 

December . . 

88. 

70. 

76.5 

88.8 

May 91. 

June 90. 

July 89.5 

August 89. 

September  .     90. 

73. 

73. 

72. 

73.5 

72.5 

80.0 
79.5 
78.2 
79.1 
79.6 

85.9 
88.9 
88.9 
89.5 
87.3 

1899. 
January  . . . 
February. . . 
March 

S4. 
85. 

69. 
66 
70 

■ 

75.9 
76.9 
77.6 

90.5 
87.5 
83.7 

TEMPERATURE  AND  RELATIVE  HUMIDITY  AT  FORT  SAN  CARLOS  STATION,  1898. 

Day. 

Max.          Min. 
82.5           70.5 

Mean. 

Moan 
t-t'. 

Relative 
humidit}\ 

MAHcn. 

Day 

Max. 

Min. 

Mean. 

Moan 
t-t'. 

Relative 
humidity. 

w . . . 

75.5 

3.5 

85 

20. . . 

86.5 

71.0 

78.5 

8.0 

67.5 

10.... 

83.0           72.0 

77.5 

4.5 

80.5 

21... 

84.0 

72.0 

78.0 

6.5 

73 

11... 

85.0           72.5 

78,5 

6.0 

75 

22... 

83.0 

72.0 

78.5 

8.0 

67.5 

12... 

84.5           72.5 

78.0 

5.0 

79 

23. . . . 

81.0 

71.5 

76.5 

5.0 

78 

13... 

88.0           71.0 

78.5 

5.0 

79 

24... 

83.0 

71.0 

77.5 

3.5 

85 

14... 

87.0           74.0 

79.5 

6.5 

73 

25... 

8 

2.0 

73.0 

77.0 

3.0 

87 

lo. . . • 

86.5           72.5 

80.0 

6.5 

73 

26.... 

85.0 

71.0 

77.5 

5.0 

78.5 

16... 

87.0           71.0 

78.5 

6.5 

73 

27.... 

84.0 

72.0 

77.5 

4.0 

83 

17... 

86.0           73.0 

78.5 

7.0 

71 

28.... 

86.0 

70.0 

78.0 

6.5 

73 

18... 

82.0           73.0 

77.5 

5.5 

76.5 

29.... 

8 

5.0 

72.0 

79.5 

7.5 

70 

19... 

87.0           75.0 

80.0 

9.0 

64 

TEMPERATURE  AND  RELATIVE  HUMIDITY  AT  FORT  SAN  CARLOS  STATION,  1898. 

April. 

Max. 



May. 

Day. 

Max. 

Min. 

Mean. 

Mean 
t-t. 

Relative 
humidity. 

Min. 

Mean. 

Moan 
t-t'. 

Relative 
humidity. 

1... 

83.0 

72.0 

77.0 

4.0 

83 

82.0 

75.0 

78.0 

2.5 

89 

a... 

88.0 

73.5 

80.0 

7.0 

72 

82.5 

74.5 

77.5 

2.5 

89 

8... 

H6.0 

72.0 

77.5 

6.5 

78 

87.0 

77.0 

81.0 

4,0 

84 

4. . . 

85.0 

73.0 
75.0 

78.0 
75.5 

4.5 
1.5 

81 
93 

89.0 
86.0 

76.0 
74.0 

80.0 
79.5 

4.0 
5.0 

83 

d .  .  . 

77.0 

79 

6. . . 

83.5 

75.5 

77.0 

2.0 

91 

89.0 

75.5 

80.5 

4.0 

83.5 

7. .. 

82.5 

76.0 
74.5 
72.0 

78.0 
79.0 
78.0 

4.5 
7.5 
6.5 

81 
70 
73 

88.5 
91.0 

•   •   •    • 

77.0 
78.5 
79.5 

81.5 
83.5 

•   •   •   • 

4.0 
4.5 

•   •   •   • 

84 

8. . . 

86.0 

82 

tr  m    m    • 

86.0 

•    •   «    • 

10. . . 

86.5 

75.0 

74.0 
75.0 

79.0 

77.5 
79.0 

5.5 

3.0 
5.0 

77 

87 
79 

85.5 

77.0 
87.5 

78.0 

75.0 
75.5 

80.5 

76.0 
81.0 

3.0 

1.5 
4.5 

87.5 

11. .. 

87.0 

93 

X  ■««  ■    •    • 

85.0 

82 

18.  . . 

87.0 

74.0 
72.5 
74.5 

80.0 

78.5 
80.0 

6.0 
5.0 
8.0 

75 
79 
68 

84.0 
89.0 

87.5 

78.5 
75.5 
77.0 

80.5 
82.0 
80.5 

4.0 
5.0 
4.0 

83.5 

14.  . . 

85.5 

80 

15... 

87.0 

83.5 

10. . . 

88,5 

70.5 
73.0 
73.5 

79.0 
76.5 
79.0 

7.0 
2.5 
6.0 

71 
89 
75 

82.5 

•   •   •   • 

87.0 

74.5 
75.0 
74.5 

78.0 

•    •   •   • 

79.0 

3.0 

•   •   •   • 

3.0 

87 

17. . . 

80.0 

18... 

86.0 

87 

19. . . 

8K.0 

75.0 
75.0 

74.5 
74.0 
74.0 
76.5 
75.0 

80.5 
80.5 

81.0 
78.0 
75.5 
81.0 
81.0 

5.5 
6.5 

7.5 
4.5 
2,0 
6.0 
4.0 

77.5 
74 

70 
81 
91 
75 

84 

84.5 

•   •   •   • 

86.0 
79.5 
79.0 
85.0 
86.0 

76.0 
74.0 

76.5 
76.0 
73.0 
75.0 
77.0 

79.0 

•   •   •   • 

79.5 
77.0 
76.0 
79.0 
81.5 

3.0 

•   •   •    • 

2.5 
1.5 
1.5 
3.0 
3.5 

87 

20... 

87.0 

*>i 

88.0 

89 

oo 

82.0 

93 

♦>3 

80.0 

93 

»>J. 

87.0 

87 

25... 

88.0 

86 

26... 

84.5 

73.0 

77.0 

3.0 

87 

88.0 

80.0 

83.0 

6.0 

80 

27... 

86.5 

72.0 
71.0 
74.0 
72.5 

•   •  •   • 

77.0 
78.0 
80.0 
79.0 

•   •  •  • 

3.0 
5.0 
6.0 
5.5 

•   •  •   • 

87 
79 
75 

77 
. .  •  • 

90.0 
90.0 
89.5 
86.0 
85.0 

81.0 
76.5 
77.0 
76,0 
78.5 

85.0 
83.0 
78.0 
80.5 
80.0 

5.0 
4.0 
1.5 
2.5 
2.5 

80 

28... 

85,0 

84 

29... 

88.0 

93 

30... 

86.5 

89.5 

81... 

•  •••«                         •••• 

89 

316 


NICARAGUA  CANAL  COMMISSION 


TEMPERATURE  AND  RELATIVE  HUMIDITY  AT  FORT  SAN  CARLOS  STATION,  1898. 


June. 

July. 

Day. 

Max. 

Min. 

Mean. 

Mean 
t-t'. 

U'^lative 
humidity. 

Max. 

Min. 

Mean. 

Mean 
t-t'. 

Relative 
humidity. 

1 

83.0 

74.5 

78.5 

3.0 

87 

83.0 

76.0 

78.5 

3.5 

89 

o 

<tf........ 

87.5 

73.0 

81.0 

4.5 

82 

88.0 

73.5 

77.5 

3.0 

91 

8 

88.0 

75.0 

81.0 

4.5 

82 

83.0 

73.0 

78.0 

2.5 

89 

4 

86.5 

77.5 

81.0 

4.0 

84 

82.0 

76.5 

78.5 

3.0 

87 

5 

88.5 

77.0 

82.0 

4.0 

84 

81.0 

76.0 

78.0 

3.5 

89 

6 

90.0 

79.0 

84.0 

4.5 

82 

87.0 

76.0 

80.0 

3.0 

87 

7 

83.5 

76.5 

80.5 

3.0 

87.5 

82.0 

75.0 

78.0 

2.0 

91 

8 

89.5 

78.0 

83.5 

5.0 

80 

83.0 

75.5 

78.5 

3.0 

87 

9 

89.0 

78.0 

82.5 

4.0 

84 

83.5 

74.5 

78.0 

3.5 

85 

10 

87.0 

77.0 

81.5 

2.5 

IM) 

83.0 

76.0 

78.5 

3.5 

85 

11 

80.0 

76.0 

78.5 

1.5 

93.5 

87.5 

74.5 

79.6 

3.5 

85 

12 

84.0 

74.5 

79.5 

2.0 

91.5 

86.0 

76.5 

80.0 

3.5 

85 

13 

79.5 

76.0 

77.5 

1.0 

95.5 

88.0 

76.0 

81.5 

3.0 

88 

14 

79.5 

78.0 

76.0 

3.0 

87 

86.5 

73.5 

79.5 

2.5 

89 

15 

85.0 

73.0 

79.0 

1.5 

94 

89.5 

76.5 

82.0 

3.5 

86 

16 

85.0 

76.0 

80.0 

1.5 

94 

87.0 

79.0 

81.5 

3.5 

86 

17 

86.0 

77.5 

82.0 

2.5 

90 

82.0 

76.5 

79.5 

3.5 

89 

18 

88.0 

77.0 

81.5 

2.0 

92 

82.0 

73.0 

77.0 

2.0 

91 

19 

87.0 

74.0 

79.5 

2.0 

91.5 

82.5 

75.0 

78.0 

2.5 

89 

20 

87.0 

77.0 

81.0 

2.0 

93 

79.5 

73.0 

75.5 

1.5 

98 

21 

86.0 

75.0 

78.5 

2.5 

89 

75.0 

74.5 

74.5 

1.0 

95 

22 

84.5 

74.0 

79.0 

3.0 

87 

79.5 

78.5 

76.0 

1.5 

93 

33 

82.5 

75.5 

77.5 

2.0 

91 

82.0 

74.0 

77.5 

2.5 

89 

24 

81.0 

74.5 

78.0 

2.2 

91 

83.0 

75.0 

78.5 

2.5 

89 

25 

82.0 

75.0 

78.0 

2.0 

91 

81.0 

75.0 

77.5 

2.5 

89 

26 

83.0 

74.5 

77.5 

2.5 

89 

79.0 

74.0 

76.0 

1.5 

93 

27 

78.0 

73.0 

75.0 

0.7 

98 

84.0 

73.0 

mm    C 
f  4.0 

3.0 

87 

28 

81.5 

73.5 

77.5 

2.0 

91 

82.5 

78.5 

78.0 

2.0 

91 

29 

84.0 

74.0 

79.0 

2.0 

91 

79.5 

74.0 

77.5 

2.0 

91 

30 

84.0 

74.5 

79.0 

3.0 

87 

81.0 

73.0 

77.0 

2.0 

91 

31 

•    •    •    • 

•    •    •   • 

•   •   •    • 

•   •    •   • 

•    •   •   • 

85.0 

74.0 

79.0 

2.5 

89 

TEMPERATURE  AND  RELATIVE  HUMIDITY  AT  FORT  SAN  CARLOS  STATION,  1898. 


Day. 


AU(JU8T. 

r 

s 

Max. 

Min. 

Mean. 

Mean 
t-f. 

Relative 
humidity 

80.0 

77.0 

79.0 

2.0 

91 

83.0 

73.5 

77.0 

2.0 

91 

88.0 

74.5 

78.0 

3.5 

89 

82.5 

74.5 

77.0 

1.5 

93 

84.0 

76.0 

78.5 

3.0 

91 

85.0 

74.0 

79.0 

3.5 

89 

80.0 

75.0 

77.0 

1.5 

93 

84.0 

75.0 

78.0 

2.0 

91 

77.5 

74.0 

76.0 

1.5 

93 

85.0 

76.5 

79.5 

2.5 

89 

81.0 

76.0 

78.0 

1.5 

93 

81.0 

74.5 

77.0 

1.5 

93 

84  0 

75.0 

78.5 

1.5 

93.5 

85.0 

75.0 

79.0 

2.5 

89 

86.0 

78.0 

81.0 

2.0 

92 

Sbptembbb. 

Max. 

Min. 

Mean. 

Mean 
t-t'. 

Relative 
humidity. 

84.0 

75.5 

79.0 

2.0 

91 

85.0 

73.0 

78.0 

2.0 

91 

81.5 

74.5 

77.5 

1.5 

98 

86.0 

75.0 

79.5 

2.0 

91.5 

86.0 

78.5 

81.5 

5.0 

80 

79.0 

75.0 

76.5 

1.0 

95 

79.0 

75.0 

77.0 

2.0 

91 

80.0 

76.0 

77.5 

2.0 

91 

83.0 

72.5 

77.1 

1.5 

93 

85.0 

73.0 

79.5 

3.0 

87 

81.5 

75.0 

79.0 

2.2 

91 

85.0 

75.0 

79.5 

2.5 

89 

86.0 

77.0 

80.5 

3.0 

87.5 

82.0 

74.0 

77.5 

2.5 

89 

86.0 

75.0 

79.5 

3.0 

87 

1, 

3 

3. 
4. 
5 

6. 
f  , 
8. 
9. 
10 

11. 
12. 
13. 
14, 
15. 


APPENDIX   III.— HYDROGRAPHIC   REPORT 


317 


TEMPERATURE  AND  RELATIVE  HUMIDITY  AT  FORT  SAN  CARLOS  STATION,  1898.— Continued. 


Daj'. 

August. 

8EPTBMBER. 

r 

\ 

'■ 

'^ 

Max. 

Min. 

Mean. 

Mean 
t-t'. 

Relative 
humidity. 

Max. 

Min. 

Mean. 

Mean 
t-t'. 

Relative 
humidity. 

16 

88.0 

78.0 

81.5 

.  3.5 

86 

85.0 

74.0 

79.5 

2.5 

89 

17 

87.0 

78.5 

81.5 

3.0 

88 

87.0 

74.5 

81.0 

3.0 

88 

18 

88.5 

77.0 

81.5 

3.5 

86 

88.0  • 

77.0 

82.0 

5.5 

78 

19 

89.0 

'74.0 

79.5 

3.5 

85 

83.0 

76.0 

78.5 

2.5 

89 

20 

84.0 

74.5 

78.5 

3.0 

87 

85.0 

74.0 

78.0 

2.5 

89 

21 

84.0 

76.0 

79.5 

2.5 

89 

85.5 

74.0 

79.0 

4.0 

83 

22 

88.5 

73.5 

79.5 

3.0 

87 

87.0 

74.0 

79.0 

3.0 

87 

23 

■                           •    •   •    • 

75.5 

•   •   •   • 

1.0 

•    •   •    • 

84.0 

73.5 

79.5 

3.0 

87 

24 

84.0 

75.0 

78.5 

2  5 

89 

88.0 

76.0 

82.0 

3.5 

86 

2.5 

87.5 
85.0 

76.0 
76.5 

80.5 
79.5 

3.0 
2.0 

87.5 
91.5 

88.5 
90.0 

78.0 
75.0 

83.0 
80.5 

4.5 
3.6 

82 

26 

85 

27 

80.0 

76.0 

80.5 

2.5 

89.5 

88.0 

75.0 

80.5 

4.0 

83.5 

28 

86.0 

78.0 

80.5 

3.5 

85.5 

87.5 

76.5 

80.5 

3.0 

87.5 

29 

83.0 

74.5 

79.0 

2.5 

89 

88.0 

80.0 

84.0 

4.5 

82 

30 

87.0 

79.0 

81.5 

8.5 

86 

90.0 

78.0 

84.0 

.5.5 

78.5 

31 

87.0 

75.0 

79.5 

2.5 

89 

•   •   •   • 

■    •   • 

•    •   •    • 

•   •   •   • 

•   •   •    • 

TEMPERATURE  AND  RELATIVE  HUMIDITY  AT  FORT  SAN  CARLOS  STATION,  1898. 


October. 

' 

November. 

Day. 

Max. 

Min. 

Mean. 

Mean 
t-t'. 

Relative 
humidity. 

r 

Max. 

Min. 

Mean. 

Mean 
t-f. 

Relative 
humidity. 

1 

SK).0 

79.0 

82.5 

4.1 

84 

86.0 

79.0 

82.5 

4.0 

84.0 

•> 

•^  •   •    •    •  •    • 

81J.0 

78.0 

83.0 

4.5 

82 

88.0 

81.0 

83.5 

6.0 

76.5 

3 

88.0 

79.0 

82.5 

3.5 

86 

88.0 

77.0 

81.5 

4.0 

84.0 

4 

87.0 

75.0 

79.5 

3.0 

87 

82.0 

75.0 

77.5 

2.0 

91.0 

5 

82.0 

75.0 

78.0 

2.0 

91 

82.5 

75.0 

78.5 

2.0 

91.0 

6 

87.0 

74.0 

79.5 

3.0 

87 

81.5 

76.0 

78.0 

2.0 

91.0 

i 

87.5 

76.0 

82.0 

3-5 

86 

a5.0 

75.0 

79.5 

3.0 

87.0 

8 

78.5 

76.0 

77.0 

1.5 

93 

88.5 

75.0 

80.5 

4.0 

83.5 

9 

83.5 

76.0 

79.5 

2.0 

91.5 

82.0 

76.0 

78.0 

1.5 

93.0 

10 

86.0 

75.0 

80.5 

3.5 

85.5 

83.0 

76.0 

79.0 

2.5 

89.0 

11 

88.0 

74.0 

80.5 

2.5 

89.5 

85.0 

76.0 

79.5 

2  5 

89.0 

12 

88.0 

77.0 

81.5 

3.0 

88 

82.0 

75.0 

78.0 

1.5 

93.0 

13 

82.0 

75.0 

78.5 

2.0 

91 

77.0 

74.0 

75.5 

1.0 

95.0 

14 

84.0 

74.5 

78.0 

1.5 

98 

80.0 

74.0 

76.5 

1.5 

93.0 

15 

84.0 

76.0 

79.0 

2.0 

91 

81.0 

74.5 

77.0 

1.5 

93.0 

16 

85.0 

74.0 

78.5 

2.0 

91 

74.5 

73.0 

74.0 

1.5 

9.3.0 

17 

86.0 

75.0 

79.0 

2.0 

91 

78.0 

73.5 

75.5 

1.5 

93.0 

18 

8.5.0 

75.0 

78.5 

2.0 

91 

79,0 

74.0 

75.5 

1.5 

93.0 

19 

84.0 

7.5.0 

80.0 

3.0 

87 

82.0 

72.0 

79.5 

3.0 

87.0 

20 

86.0 

76.0 

80.5 

2.5 

89.5 

78.0 

73.0 

75.5 

1.5 

93.0 

21 

86.5 

77.0 

81.0 

3.0 

88 

82.0 

74.0 

77.5 

2.5 

89  0 

22 

87.0 

77.0 

80.5 

3.0 

87.5 

82.0 

74.0 

77.5 

2.5 

89.0 

23 

84.0 

76.0 

79.0 

2.5 

89 

83.5 

75.0 

78.5 

3.0 

87.0 

24 

82.5 

75.0 

78.0 

2.0 

91 

85.0 

75-0 

78.5 

2.0 

91.0 

25 

77.0 

75.0 

76.0 

1.5 

93 

78.0 

74.0 

76.0 

1.5 

93.0 

26 

82.5 

75.0 

78.0 

2.0 

91 

81.0 

74.5 

77.0 

1.0 

95.0 

27 

83.5 

74.0 

78.0 

2.0 

91 

79.0 

74.0 

76.5 

1.0 

9.5.0 

28   

85.0 

74.0 

80.0 

2.5 

89 

81.0 

75.0 

77.5 

1.5 

93.0 

29 

86.0 

78.5 

82;  0 

4.0 

84 

83.0 

76.0 

78.5 

2.0 

91.0 

30 

88.0 

79.0 

83.0 

3.5 

86 

80.0 

74  0 

76.5 

2.5 

89.0 

31 

87.0 

77.0 

81.5 

2.5 

90 

•    •   •   • 

•    •   •    • 

•   •   •   • 

•   •   •   • 

•     •     •     a 

318 


NICARAGUA  CANAL  COMMISSION 


TEMPERATURE  AND  RELATIVE  HUMIDITY  AT  FORT  SAN  CARLOS  STATION.  1898-99. 


DECRMnKK,   18»H. 

Januakv,  1W». 

Day. 

Max. 

Mln. 

Mean. 

Mean 
t-t'. 

Helative 
humidity. 

Max. 

Min. 

Mean. 

Mean 
t-t'. 

Relative 
humidity. 

1 

76.5 

7:j.o 

75.0 

0.9 

95 

K2.0 

72.0 

76.5 

3.5 

8.5 

87.0 

74.0 

79.8 

2.3 

89 

82.0 

73.0 

76.5 

3.0 

H7 

3 

83.0 

76.0 

70.0 

2.4 

89 

83.0 

72.0 

76.5 

3.0 

87 

4 

84.5 

75.0 

79.1 

2.8 

87 

80.0 

72.0 

75.5 

1.5 

93 

5 

82.0 

75.0 

77.3 

3.0 

87 

80.0 

74.0 

76.5 

.2.0 

91 

6 

80.0 

74.0 

77.0 

2.0 

91 

80.0 

73.0 

75.5 

2.0 

9  1 

7 

82.5 

74.0 

77.5 

3.2 

87 

S3.0 

73.0 

76.5 

3.0 

87 

8 

79.0 

73.0 

75.6 

2.3 

89 

K2.0 

73  0 

76.0 

2.5 

S!» 

9 

84.0 

73.0 

77.0 

3.0 

87 

7\hO 

73.0 

75.5 

1.5 

93 

10 

78.5 

73.0 

75.5 

1.2 

95 

7^).0 

72.0 

75.5 

2.0 

91 

11 

81.5 

73.0 

77.1 

2.8 

87 

79.0 

71.0 

75.0 

1.5 

93 

12 

81.0 

71.0 

76.3 

3.0 

87 

78.0 

73.0 

75.5 

1.0 

!»5 

13 

81.0 

72.0 

76.6 

2.6 

89 

79.0 

75.0 

76.5 

1.0 

9.5 

14   

83.0 

72.0 

76.3 

3.7 

85 

80.0 

74.0 

76.0 

1.5 

9.S 

15 

82.0 

70.5 

76.1 

2.6 

89 

81.0 

75.0 

77.5 

1.5 

93 

16 

76.0 

72.0 

73.6 

1.3 

93 

78.0 

73.0 

75.5 

1.0 

9.5 

17 

78.0 

71.5 

74.1 

1.5 

93 

80.0 

71.0 

75.5 

1.5 

9.^ 

18 

81.0 

72.0 

76.0 

2.7 

89 

82.0 

73.  a 

76.0 

2.5 

89 

19 

82.0 

70.0 

74.6 

1.6 

93 

82.0 

73.0 

77.0 

3.5 

85 

20 

82.0 

72.0 

77.0 

2.0 

91 

77.0 

72.0 

74.0 

1.5 

93 

21 

84.0 

71.5 

76.5 

2.9 

87 

77.0 

72.0 

74.5 

1.5 

93 

22 

82.0 

73.0 

76.0 

2.7 

89 

78.0 

71.0 

74.0 

2.0 

91 

23 

84.0 

72.0 

74.0 

0.4 

98 

82.0 

72.0 

76.5 

2.5 

89 

24 

84.0 

78.0 

77.0 

4.0 

83 

84.0 

72.0 

77.5 

2.5 

89 

25 

84.0 

72.0 

77.0 

3.0 

87 

83.0 

74.0 

78.0 

2.5 

89 

26 

81.0 

74.0 

76.6 

4.0 

82.5 

78.0 

72.0 

75.5 

2.0 

91 

27 

80.0 

71.0 

76.6 

2.6 

89 

83.0 

71.0 

77.0 

2.0 

91 

28 

77.0 

72.0 

74.6 

2.6 

88.5 

82.0 

69.0 

75.0 

2.0 

91 

29 

80.0 

72.0 

75.6 

2.0 

91 

80.0 

72.0 

75.0 

2.5 

89 

80 

80.0 

73.0 

76.3 

2.3 

89 

84.0 

72.0 

76.5 

3.5 

85 

31 

88.0 

75.0 

81.0 

5.7 

78 

81.0 

69.0 

75.0 

2.5 

89 

TEMPERATURE  AND  RELATIVE  HUMIDITY  AT  FORT  SAN  CARLOS  STATION,  1899. 


Day, 


Febrcaky. 


Maroh. 


Max. 


Min. 


Mean. 


Mean 
t— t'. 


Helative 
humidity. 


Max. 


Min. 


Mean. 


Mean 
t-t'. 


Relative 
humidity. 


1. 

2 

8 

4, 

5. 

6. 
7, 
8. 
9. 
10. 

11. 
12. 
13. 
14. 
15 


80 
83 
82 
78 
83 

82 
83 
85 
80 

85 

85 
78 
80 
75 
79 


73 

76.5 

71 

76.5 

72 

76.5 

72 

75.0 

72 

77.0 

72 

76.5 

72 

77.5 

75 

80.0 

74 

77.5 

72 

78.5 

74 

78.5 

73 

75.5 

72 

75.0 

66 

70.5 

69 

74.0 

2.5 
3.0 
4.0 
2.5 
3.5 

2.5 
3.5 
3.5 
2.5 
4.0 

3.5 
1.0 
2.0 
3.5 


89 

87 
82 
89 
85 

89 
85 
85 
89 
83 

85 
95 
91 
83 


75 

80 
75 

78 
84 

83 
80 
76 
82 
83 

82 
83 
80 
83 
79 


72 

71 
73 

74 
76 

74 
74 
72 

71 
70 

70 
72 
72 
74 
72 


73.0 
75,5 
74.0 
76.5 
79.5 

77.0 
76.0 
73.5 
74.5 
75.0 

75.0 
77.0 
76.0 
78.0 
76.5 


1.5 
2-5 
2.5 
2.5 
5.5 

3.5 
8.5 
3.5 
3.5 
4.0 

8.5 
8.5 
2.5 
8.5 
2.5 


93 
89 
89 
89 
77 

85 
85 
89 

s^ 

82 

8h 
85 
80 
85 
89 


APPENDIX   III.— HYDROGRAPHIC   REPORT 


319 


TEMPERATURE  AND  RELATIVE  HUMIDITY  AT  FORT  SAN  CARLOS  STATION,  1899.— Continued. 


FKBRrARY. 


March. 


Day 


16. 
17, 

18. 
19. 
20. 

21. 
22. 
28. 
24. 
25. 

26. 
27. 
2«. 
29. 
80. 
31. 


Max. 

80 
76 
80 
88 

82 

79 
80 
85 
79 
83 

79 

85 
83 


Min. 


70 
72 
74 
72 
73 

74 
77 
77 
73 
74 

73 
74 
71 


Mean. 


75.0 
745 
76.0 
76.5 
77.0 

76.5 
78.0 
79.5 
76.0 
77.5 

76.0 
78.5 
76.5 


Mean 

t-t/ 

2.5 
1.5 
2.0 
2.5 
2.5 

2.0 
3.0 
3.5 
8.5 
3.5 

2.0 
8.5 
8.5 


Kelative 
humidity. 


89 
93 
91 
89 
89 

91 
87 
85 
85 
85 

91 

85 
85 


Max. 


K6 
85 
84 
87 
86 

87 
84 
87 
86 
86 

90 

■   •   • 

90 
89 
89 
79 


Min. 


Mean. 


74 

79.0 

76 

79.0 

72 

1  i.O 

74 

79.5 

75 

79.5 

73 

78.5 

73 

78.0 

74 

79.5 

72 

79.5 

71 

78.5 

73 

80.5 

•   • 

74 

■    ■   •   • 

81.5 

76 

K1.5 

78 

81.0 

75 

78.0 

Moan 
t-t. 


Relative 
humidity 


4.0 
3.5 
4.5 
4.0 
3.5 

4.0 
4.0 
5.0 
5.5 
4.5 

0.0 

•   •   • 

6.0 
5.5 
5.5 
2.0 


83 
85 
80 
88 
85 

88 
83 
79 
<  < 
81 

75 

I  •   • 

76 

78 
78 
91 


TEMPERATURE  AND  RELATIVE  HUMIDITY  AT  CAMP  SABALOS. 


Month. 


Temperature. 


Max. 


Min. 


Mean. 


Mean 

relative 

humidity. 


Temperature. 


invrui-ii. 

Max. 

Min. 

Mean. 

September  . 

90 

71 

78.6 

October 

90 

71 

78.2 

November. . 

8H 

68 

77,0 

December  . . 

86 

65,2 

75.6 

1899. 

January 

86 

66.0 

75.2 

February. . . 

86 

64.0 

76.0 

March 

90 

68.0 

77.1 

Mean 

relative 

humidity. 


1898. 
February. . . 

March 

April 

May 

June 

July 

August 


90 
90 
89 
89 

89 
89 

87 


67 

75.5 

87.2 

69 

76.7 

84.8 

66 

76.8 

85.8 

71 

77.8 

87,8 

71 

77.7 

90.0 

71 

77.1 

92.0 

70 

77.5 

91.0 

87.4 
87,4 
90.4 
89.0 

90.7 
87.6 
85.0 


TEMPERATURE  AND  RELATIVE  HUMIDITY  AT  CAMP  SABALOS,  1898. 

Observed  at  7  A.  M.,  12  M.  and  7  P.  M. 


1 

February. 

A 

March. 

Day. 

Max. 

Min. 

Moan. 

Mean 

t-t'. 

Relative 
humidity. 

r 

Max. 

Min. 

Mean. 

Mean 
t-t'. 

Kelative 
humidity. 

1 

80 
79 
76 
79 

•  •   •   •   • 

•  •   •   •   • 

t                       •   •   ■   • 

•  •   •   •    • 

■                        •   •   •   • 

• 

•  •   •   •   • 

81 
80 

81 

•  •   •  •   • 
•   •   •  • 

72 
72 
73 
69 

•  •   •   • 

•  •   •   • 

•  •   •   • 

•  •   •   •                       i 

•  •   •   • 

72 
72 
73 

•  •  •   •                        fl 

•  •    •    •                              a 

77 
75 
74 
75 

»   •  •    • 

76 
76 
77 

•  •   • 

•  •  •                          « 

3.0 
1.5 
1.5 
2.5 

•   •   •   • 

»   •   •   • 
»   •   •   • 
»   •   •   • 

•  •   • 
■   •   •   • 

2.5 
2.5 
8.0 

k   •   •   • 

•  •   • 

87 
98 
98 

89 

•  •   •   • 

•  •   •   • 

•  •   •   • 

•  •   •   • 

•  «   •   • 

•  •   •   • 

89 
89 
87 

.... 

.... 

82 
84 
«9 
81 
82 

84 
88 
85 
78 

•  •   •   • 

•  •   •   • 

8ti 
89 
88 

•  •   •   • 

70 
71 
70 
78 
73 

74 
78 
72 
78 

•  •   •   • 

•  ■   •   • 

70 
69 
70 

•  •   •    • 

75 
77 

79 
76 

77 

77 
76 
77 
75 

•  •   •   • 

•  •   •   • 

77 
78 
78 

•  •   •   • 

2.5 
2.5 
4.0 
1.0 
2.0 

2.5 
2.0 
8.0 
2.0 

•   •   •   • 

•    •  •   • 

8.5 

4,0 

4.0 

.... 

89 

2   

89 

8 

4 

5 

6 

7 

8 

83 
95 
91 

89 
91 

87 

9 

10 

11 

12 

91 

•    •   •   • 
•    •   •    • 

85 

13 

14 

83 
83 

15 

•   «   •   • 

320 


NICARAGUA  CANAL  COMMISSION 


TEMPERATURE  AND  RELATIVE  HUMIDITY  AT  CAMP  SABALOS,  1898.— Continued. 


Day. 

February. 

tfean 
t-t'. 

Min. 

March. 

Max. 

MiQ. 

Mean. 

Relative 
humidity. 

Max. 

Mean 

Mean 
t-t'. 

Relative 
humidity. 

16 

17 

18 

19 

20 

21 

23 

90 
88 
80 
86 
78 

80 
83 

84 

•   •   •   • 

•  •   ■    •    • 

•  •    •   •    • 

70 
69 
70 
67 
72 

73 

70 
70 

•  •   •   • 

•  •    •   • 

•  •   •    • 

•  ■   •    •                           • 

■    •   •   • 

•  ■   •    • 

•  •   •   • 

•  •   •    • 

77 
76 

•    •   ■ 

>  •   •    • 

>  •   •    ■ 

•   •   •    • 
»    •    •   ■ 

5.0 
4.5 
2.5 
4.0 
1.6 

2.0 
8.5 
8.5 

»    •   •   • 

»     m     m     • 
»     •     •     • 

•    •   •   ■ 

•  •   •   • 

•  •   ■    • 

•  •  •   • 

78 
80 
88 
82 
98 

91 
84 
85 

•  •   •   • 

•  •   •    • 

•  •   ■    • 

89 

•  •  •  • 
88 

•   •   •   • 

90 

87 
81 
85 
79 

■    •   •   • 

86 
83 
85 
87 
84 
83 

70 

•  •   •    • 

69 

■    •   •   • 

70 

71 
71 
71 
71 

•  •   •   • 

71 
73 
69 
70 
69 
72 

77 

•  •   •   • 

77 

•  •   •   • 

78 

77 
75 
76 
75 

•  •  •   • 

77 

76 
77 

77 

77 
77 

4.0 

•  •   •   • 

5.0 

•  •   •    • 

6.0 

4.5 
8.5 
3.5 
2.0 

•  •    •    • 

85 
3.5 
4.5 
5.5 
5.0 
3.5 

83 

•  •   ■   • 

78 

•  •   •    • 

75 

80 

84 

33 

74 
76 
74 

74 
75 
76 

•    •   •   • 

84 

24 

25      . 

91 

26 

27 

28 

29 

30 

85 
85 
80 
76 

78 

31    

•    •  • 

k 

85 

TEMPERATURE  AND  RELATIVE  HUMIDITY  AT  CAMP  SABALOS,  1898. 


Day. 

Aphii>. 

-*- 

May. 

' "  \ 

Max. 

Min. 

Mean. 

Mean 

tr-t\ 

Relative 
humidity. 

Max. 

Min. 

Mean. 

Moan 
t-t'. 

Relative 
humidit}'. 

1 

■                         •   •   •    • 

•    •   •   • 

•   •   •    • 

•   •   •    • 

•   •   •   • 

78 

71 

75 

1.5 

93 

2 

89 

71 

79 

6.5 

73 

82 

72 

77 

3.5 

89 

3 

84 

69 

77 

4.5 

80 

86 

72 

79 

4.5 

81 

4 

79 

71 

75 

8.0 

87 

84 

71 

77 

3,5 

85 

5 

75 

85 

71 
75 

73 
79 

1.0 
8.0 

95 
87 

83 

•   •   ■   • 

72 
73 

76 

•   •   •    • 

2.0 

•   •   •   ■ 

91 

6 

•    •   •    • 

7 

85 

74 

78 

2.5 

89 

84 

73 

79 

3.0 

89 

8 

86 

71 

78 

4.5 

81 

83 

73 

78 

2.5 

89 

9 

•                        ■    •    •   • 

•   •   •   • 

•    •    •   • 

.... 

•    •    •   • 

84 

77 

80 

4.0 

83 

10 

81 

73 

76 

2.5 

89 

83 

73 

77 

2.0 

91 

11 

79 

73 

76 

1.5 

93 

76 

75 

76 

1.0 

95 

12 

85 
86 
79 

72 
70 
70 

78 
78 
75 

8.5 
4.5 
2.5 

85 
81 
89 

86 

84 

•    •   •   • 

78 
73 
73 

79 

78 

•      •      •      9 

8.5 
3.5 

•    •   •   • 

85 

13 

85 

14 

•    •   •    • 

15 

86 

66 

76 

4.5 

80 

85 

74 

78 

3.5 

89 

16 

■                         •    •   •   • 

•    •   •    • 

•   •   •   • 

•    •   •   • 

.... 

80 

73 

76 

2.0 

91 

17 

79 

85 

73 
70 

76 
77 

1.5 
8.5 

93 

85 

83 
83 

73 
73 

78 
78 

1.5 
2.5 

93 

18-. 

89 

19 

85 

71 

77 

4.0 

83 

89 

74 

79 

4.0 

83 

20 

87 

69 

77 

4.5 

80 

84 

73 

77 

2.5 

89 

21 

88 

78 

79 

4.5 

81 

83 

73 

77 

2.5 

89 

22   

79 

68 

74 

1.5 

93 

80 

73 

76 

2.0 

91 

28 

•   •   ■   • 

•    •   •    • 

•    •   •   • 

•   •   •   • 

«   •   •   • 

77 

71 

74 

1.6 

98 

34 

87 

72 

79 

4.5 

81 

85 

72 

79 

3.5 

86 

25   

87 

70 

78 

4.5 

81 

84 

73 

79 

3.5 

85 

26 

81 

71 

75 

2.6 

89 

86 

73 

79 

4.5 

81 

27 

79 

71 

75 

1.5 

93 

88 

73 

79 

3.5 

86 

28 

85 

70 

77 

4.0 

83 

85 

73 

78 

8.0 

87 

29 

88 

69 

78 

4.5 

81 

86 

76 

80 

8.0 

87 

80 

•   •   •    • 

•   •   •    • 

•   •   •   • 

.... 

.... 

86 

75 

79 

3.0 

87 

31 

■   •   •   • 

•   •  •   • 

•   •   •    • 

•  • . . 

.... 

86 

75 

79 

2.5 

89 

APPENDIX   III.— HYDROGRAPHIC   REPORT 


321 


TEMPERATURE  AND  RELATIVE  HUMIDITY  AT  CAMP  SABALOS,  1898. 


June. 

July. 

Day. 

Max. 

Mln. 

Mean. 

Meaa 
t-t'. 

Relative 
humidity. 

r 

Max. 

Mln. 

Mean. 

Mean 
t-t'. 

Relative 
humidity. 

1 

79 

87 
87 

73 
73 
73 

70 
79 
79 

1.5 
4.0 
4.5 

93 
83 
81 

81 
79 
85 

78 
73 
?3 

77 
75 

78 

1.5 
1.5 
3.5 

Oo 

3 

93 

3 

81» 

4 

81 
86 

87 

73 
74 

74 

76 

78 

80 

1.5 
3.0 

3.5 

93 

87 

85 

84 
78 

83 

74 
73 

72 

78 
75 

77 

3.0 
1.0 

3.5 

91 

5 

95 

6 

89 

7 

88 
86 

75 
74 

81 
80 

3.0 
3.0 

86 
87 

•  •  •  • 

•  •   •  • 

•  •  •   • 

•  •   •   • 

•   •  • 
•   •   •   • 

•  •   ■   • 

•  •   •   • 

8 

■   •   ■   • 

9 

85 

74 

79 

3.0 

91 

•   •   •   • 

•   •   •   • 

•   •  •   • 

•   •   •   • 

•    •   •   • 

10 

88 

75 

80 

8.0 

87 

•   •   •   • 

•   •   •   ■ 

•   •   •   • 

•   •   «   • 

■   •   •   • 

11 

78 

75 

76 

0.5 

98 

•   •   •   • 

•   •   •   • 

•   •  •   • 

■   •   •   • 

•   •   •   • 

13 

83 

73 

77 

3.5 

89 

•   •   •  • 

•   ■   •   • 

•    •   •   • 

•   •  •   • 

•    •   •   • 

13 

80 

74 

76 

1.5 

93 

89 

74 

80 

4.0 

88 

14 

•   •   •   • 

•   •   •   • 

«   •   •   • 

•    •   •   • 

•   •  •   • 

82 

74 

78 

3.0 

91 

15 

83 
81 

73 
71 

78 
1 1 

3.5 
1.5 

89 
93 

89 
86 

75 
75 

81 
80 

4.0 
3.5 

84 

16 

89 

17 

81 
88 

75 
75 

79 
79 

3.0 
3.5 

91 

85 

81 

84 

75 
75 

78 
79 

1.5 
1.5 

98 

18 

94 

19 

80 

73 

79 

4.0 

83 

81 

73 

76 

1.5 

93 

20 

81 

73 

76 

1.5 

93 

78 

74 

75 

1.5 

98 

21 

•   •   ■   • 

•   •   •   • 

•   •   •   ■ 

•   •   •   • 

•   •   •   • 

74 

73 

74 

1.0 

95 

22 

•   •   •   • 

•   •   ■   • 

•   •   •   • 

•   •   •   • 

m    •    •    • 

76 

73 

75 

1.0 

95 

23 

79 

74 

76 

1.5 

93 

80 

74 

77 

1.5 

93 

24 

79 
79 

73 
78 

76 
76 

1.0 
1.5 

95 
93 

83 
79 

74 
74 

78 
76 

1.5 
1.5 

98 

26 

98 

26 

81 

75 

77 

1.0 

95 

80 

75 

76 

1.5 

93 

27 

78 

73 

75 

1.5 

93 

83 

71 

77 

1.5 

93 

28 

81 

73 

76 

1.5 

93 

79 

73 

77 

1.5 

98 

29 

83 
86 

•   •   •   • 

70 
73 

•   •   •   • 

76 
79 

•   •   •   • 

2.0 
3.5 

•   •   •   ■ 

91 

89 

.  • . . 

79 
79 
80 

74 
78 
74 

76 
76 

78 

1.0 
1.5 
1.5 

95 

30 

98 

31 

98 

TEMPERATURE  AND  RELATIVE  HUMIDITY  AT  CAMP  SABALOS,  1898. 


August. 

Sbitbmbrr. 

Day. 

Max. 

Min. 

Mean. 

Mean 
t-t. 

Relative 
humidity. 

Max. 

Min. 

Mean. 

Mean 
t-t'. 

Relative 
humidity. 

1 

81 

73 

77 

1.5 

93 

85 

74 

79 

3.5 

85 

3 

78 

78 

75 

1.0 

95 

82 

74 

77 

3.0 

91 

8 

87 

»                        •    •   •   • 

73 

■    ■   •   • 

79 

•   «   •   • 

3.5 

•   •   •   • 

85 

•   •   •   • 

83 
86 

74 
74 

78 
78 

1.0 
3.5 

96 

4 

89 

6 

»                       •   •  •  • 

78 
77 
85 

•   «   •  • 

73 
73 
73 

•   •   •   • 

76 
75 
80 

•   •   •   • 

1.0 
1.0 
3.5 

•    •   •   • 

95 
95 

89 

88 

83 
80 
81 

74 

73 
74 
75 

81 

77 
70 

77 

3.0 

1.5 
1.5 
1.5 

88 

6 

93 

7 

98 

8 

93 

9 

79 
85 

74 
73 

76 
79 

1.5 
3.5 

93 
85 

84 
88 

74 
74 

78 
79 

3.5 
3.0 

89 

10 

87 

11 

81 

73 

.      77 

3.5 

89 

79 

74 

76 

1.5 

98 

13 

83 
83 
84 

75 
74 
73 

79 

77 
77 

1.0 
l.O 
1.5 

96 
95 
98 

79 

87 

•   •   ■   • 

73 
73 

•   •   •   • 

76 
79 

•   •  •   t 

1.0 
3.0 

•    •   •   • 

95 

13 

87 

14 

•   •    •   • 

15 

83 

73 

78 

1.5 

93 

90 

72 

79 

4.5 

81 

21 

■ 

322 


NICARAGUA  CANAL  COMMISSION 


TEMPERATURE  AND  RELATIVE  HUMIDITY  AT  CAMP  SABALOS,  1898.— Continued. 


August. 

-*- 

September. 

Day. 

Max. 

Min. 

Mean. 

Mean 
t-t'. 

Relative 
humidity. 

Max. 

Min. 

Mean. 

Mean 
t-t'. 

Relative 
humidity. 

16 

17 

86 
86 

75 
78  • 
70 
73 
73 

74 
73 
74 
74 
74 

75 
75 

•   •   •   • 

75 

71 
76 

79 
79 
75 
78 
76 

77 
79 

77 
77 

78 

79 

78 

•   •  •   • 

78 
76 
80 

2.5 
3.5 
2.0 
3.5 
2.5 

1.5 
2.5 
1.6 
2.0 
1.5 

2.5 
8.0 
•  • . . 
2.0 
1.5 
2.5 

89 
89 
91 
85 
89 

98 
89 
93 
91 
93 

89 

87 

•  •  •  • 

91 
93 

89 

83 
88 
89 

82 
84 

86 
86 

84 
86 
87 

90 
85 
90 
90 
90 

•   •   •   • 

73 
74 
78 
79 
78 

71 
73 
73 
73 
72 

78 
74 
74 
75 
75 

•   •   •   • 

78 
81 
80 
79 
77 

78 
77 
78 
79 
79 

80 
78 
81 
83 
83 

•   •   •   • 

1.5 
4.5 
8.5 
3.0 
3.5 

3.0 
4.0 
8.0 
8.0 
5.0 

4.0 
2.5 
4.5 
4.5 
5.0 

•   •  •  • 

93 

83 

18 

19.. 

20 

21 

22 

87 
87 
82 

83 
85 

85 
87 
89 

87 
88 

28 

24 

81 
82 

87 
87 

25 

83 

79 

26 

27 

28 

29 

80 

81 

86 
85 

<  •  •                      •  •  •  • 

84 
79 

84 

83 
89 
83 
82 
80 

TEMPERATURE  AND  RELATIVE  HUMIDITY  AT  CAMP  SABALOS,  1898. 

Day. 

OCTOBBR. 

« 

November. 

Max. 

Min. 

Mean. 

— > 
Mean      Relative 
t— t'.     humidity. 

Max. 

Min. 

Mean. 

Mean 
t-t^ 

Relative 
humidity. 

1 

88 

72 
73 
78 
71 
73 

73 
73 
75 
75 
74 

73 
74 
74 
74 
74 

72 
76 
72 
78 
75 

74 
75 
74 
74 
74 

72 
73 
76 

•  •   •   • 

•  •   •   • 

79 
80 

77 
78 
78 

78 
80 
77 
78 
79 

80 
79 
76 
76 
77 

78 
80 
78 
78 
81 

81 
81 
78 
77 
75 

74 

77 
79 

•  •   «   • 

•  •   •  • 

4.0 
3.5 
2.5 
3.5 
2.5 

2.5 
4.5 
1.0 
2.6 

4.0 

4.5 
3.5 
1.5 
1.5 
2.5 

5.0 
8.5 
8.0 
2.5 
8.5 

4.0 
4.0 
2.5 
1.5 
1.0 

1.0 
8.5 

•  •   •  •                   1 

•  •   •  • 

•  •  •   •                   1 

83 
85 
89 
85 
89 

89 
81 
95 
89 
88 

81 
85 
93 
98 
89 

79 

85    ' 
87 
89 
86 

84 
84 
89 
93 
95 

95 

85 

k    •    •    • 
k    •    •    • 
>    •    •    • 

85.8 
86.5 
86.0 
88.5 
82.0 

81.0 
81.5 
88.0 
85.0 
79.5 

84.8 
79.5 
76.3 
83.0 
79.0 

74.5 
79.0 
81.0 
83.0 
77.0 

85.0 
85.2 
86.3 
85.0 
79.0 

88.0 
78.0 
81.0 
86.7 
79.0 

74.0 
74.0 
70.0 
73.0 
74.0 

75.0 
78.0 
73.0 
78.0 
74.5 

75.0 
74.6 
74.0 
73.8 
73.0 

73.3 
73.0 

71.5 
69.5 
71.0 

73.0 
71.0 
68.0 
70.0 
78.0 

78.0 
74.0 
74.0 
73.5 
69.0 

78.6 
79.0 
77.5 
78.0 
79.0 

77.5 
77.0 
80.0 
78.0 
77.5 

78.5 
77.5 
74.5 
77.5 
75.5 

73.5 
75.5 
76.0 
75.5 
74.5 

77.5 
77.0 
77.0 
76.5 
76.5 

77.5 
76.5 
77.5 

78.5 
75.0 

4.0 
5.0 
8.5 
2.0 
2.5 

1.5 
1.0 
8.5 
2.5 
1.0 

3.5 
1.0 
1.0 
3.0 
0.5 

0.5 
1.5 
2.0 
1.5 
1.5 

2.0 
4.0 
4.0 
2.5 
1.5 

2.0 
1.5 
1.5 
Sf.O 
2.5 

88 

2 

8 

4 

90 

81 

84 

79 
85 
91 

6 

6 

85 
84 

89 
98 

7 

8 

89 
79 

95 

85 

9 

10 

84 
88 

89 
95.5 

11 

90 

89 

13 

86 

95.5 

13 

81 

95 

14 

80 

91 

15 

16 

84 
85 

98 
98 

17 

87 

98 

18 

19 

88 
86 

91 
98 

20 

^1  ■  . . .  •    • • 
22 

89 

89 
89 

93 

91 

88 

23 

24 

84 
79 

88 
89 

25 

26 

76 

76 

98 
91 

27 

83 

98 

28 

85 

^       98 

29 

87 

80 

•   •••                    •••• 

89 

APPENDIX   III.— HYDROGRAPHIC   REPORT 


323 


TEMPERATURE  AND  RELATIVE  HUMIDITY  AT  CAMP  SABALOS,  1898-9. 


«^ 

Deokmber,  1808. 

January,  180B 

>. 

Day. 

Max. 

Min. 

M€»an. 

Mean 
t-t'. 

Relative 
humidity. 

Max. 

Min. 

Mean. 

Mean 
t-t'. 

Relative 
humidity. 

1 

77.5 

73.0 

75.5 

0.9 

95 

'  84.5 

72.5 

77.5 

3.0 

87 

2 

83.0 

72.5 

78.0 

1.9 

91 

83.0 

72.0 

77.5 

3.0 

87 

8 

84.0 

73.0 

78.0 

2.3 

89 

81.0 

72.0 

76.0 

2.0 

91 

4 

86.0 

73.0 

79.0 

3.0 

87 

81.0 

71.0 

75.5 

1.5 

93 

5 

80.0 

71.8 

74.9 

1.9 

91 

80.0 

72.0 

75.5 

1.5 

93 

6 

79.0 

70.0 

75.3 

2.0 

91 

79.0 

70.0 

74.5 

1.5 

98 

7 

86.0 

72.0 

78.6 

8.9 

83 

79.0 

70.0 

74.0 

1.5 

93 

8 

78.0 

70.3 

74.7 

1.8 

91 

78.5 

71.0 

75.0 

'   2.0 

91 

9 

85.0      • 

73.0 

78.0 

8.0 

87 

79.5 

72.0 

75.5 

1.5 

98 

10 

76.0 

73.0 

• 

75.0 

1.7 

93 

79.0 

71.0 

75.0 

2.0 

91 

11 

79.3 

71.0 

74.7 

1.7 

93 

77.0 

71.0 

74.5 

1.0 

95 

12 

83.3 

71.0 

76.7 

8.1 

87 

75.0 

78.0 

74.5 

1.0 

95 

IS 

82.0 

72.0 

76.3 

2.3 

89 

83.0 

71.0 

76.5 

2.0 

91 

14 

81.0 

66.8 

74.9 

3.1 

87 

78.0 

71.0 

74.5 

1.0 

95 

15 

80.0 

68.0 

75.4 

2.9 

87 

.     80.0 

71.0 

76.5 

3.5 

85 

16 

78.0 

72.5 

74.7 

1.6 

93 

78.0 

72.0 

75.5 

2.0 

91 

17 

80.5 

71.0 

76.1 

2.5 

89 

81.0 

69.0 

75.5 

2.0 

91 

18 

81.5 

69.0 

75.6 

2.6 

89 

79.5 

72.0 

76.0 

2.0 

91 

19 

85.0 

69.0 

77.0 

4.4 

80 

81.0 

69.0 

75.5 

3.0 

87 

20 

82.5 

67.0 

76.0 

3.5 

85 

78.0 

68.5 

73.5 

1.5 

98 

21 

83.5 

69.0 

76.1 

3.3 

85 

78.0 

69.0 

76.5 

1.0 

95 

22 

81.0 

68.0 

74.0 

2.4 

88 

80.0 

67.0 

78.5 

1.0 

95 

23 

84.0 

68.0 

75.6 

2.8 

87 

81.0 

71.0 

75.5 

1.5 

93 

24 

84.0 

66.5 

74.3 

3.5 

84 

77.0 

71.0 

74.5 

2.0 

91 

25 

85.0 

65.2 

74.7 

8.6 

84 

82.0 

70.0 

75.5 

2.0 

91 

26 

81.5 

66.5 

74.0 

2.7 

88 

80.0 

70.0 

75.0 

2.5 

89 

27 

77.0 

68.0 

72.7 

12 

95 

81.0 

68.0 

75.0 

2.0 

91 

28 

79.0 

70.0 

74.3 

2.0 

91 

86.0 

68.0 

76.0 

4.0 

82 

29 

79.0 

69.0 

74.8 

1.2 

95 

82.0 

66.0 

73.0 

2.5 

88 

30 

79.0 

70.5 

75.1 

1.1 

95 

84.0 

69.5 

75.5 

3.5 

84 

81 

80.0 

70.0 

75.6 

1.8 

91 

82.0 

67.0 

74.0 

2.5 

88 

TEMPERATURE  AND  RELATIVE  HUMIDITY  AT  CAMP  SABALOS,  1899. 

Day. 

February. 

March. 

Max. 

Min. 

Mean. 

Mean 
t-t. 

Relative 
humidity. 

Max. 

Min. 

Mean. 

Mean 
t-t'. 

Relative 
humidity. 

1 

80.0 

70.5 

75.5 

2.5 

89 

79.5 

71.5 

75.5 

2.0 

91 

2 

84.5 

69.0 

76.0 

3.5 

85 

84.5 

68.0 

76.0 

4.0 

82 

3 

86.0 

67.0 

76.5 

4.5 

80 

78.0 

78.0 

75.0 

1.5 

93 

4 

82.0 

71.0 

76.0 

8.5 

85 

83.0 

71.0 

76.0 

2.0 

91 

5 

82.0 

70.0 

75.5 

8.0 

87 

87.0 

68.0 

77.5 

5.0 

78 

6 

77.0 

69.5 

73.5 

1.0 

95 

85.0 

71.0 

76.0 

3.5 

85 

7 

86.0 

72.0 

78.5 

3.5 

85 

81.0 

09.0 

74.5 

3.0 

86 

8 

85.0 

70.0 

77.0 

3.5 

85 

78.0 

69.0 

78.0, 

2.0 

91 

9 

88.0 

73.0 

76.5 

3.5 

85 

83.5 

70.0 

76.0 

4.0 

82 

10 

84.0 

71.0 

77.5 

8.5 

85 

84.5 

69.0 

75.5 

4.0 

82 

11 

83.0 

73.0 

77.5 

2.5 

89 

86.0 

68.5 

75.5 

4.0 

82 

12 

•   •   •  • 

74.0 

•  •   •  • 

•   •  «   • 

.... 

77.5 

71.0 

74.0 

1.0 

95 

13 

81.5 

70.0 

74.5 

2.5 

88 

82.0 

78.0 

76.5 

L5 

93 

14 

77.0 

64.0 

70.5 

8.0 

86 

83.5 

74.0 

78.5 

2.5 

89 

16 

79.0 

69.5 

74.0 

1.5 

93 

84.5 

72.0 

76.5 

2.5 

89 

16 

81.0 

68.5 

75.0 

1.5 

98 

87.0 

73.5 

79.0 

4.0 

88 

17 

78.5 

71.5 

75.0 

1.5 

93 

83.0 

71.5 

76.5 

2.5 

89 

18 

79.5 

72.0 

76.0 

2.0 

91 

86.5 

70.0 

77.5 

3.5 

85 

19 

83.0 

71.0 

76.5 

2.5 

89 

88.0 

70.0 

79.5 

4.5 

81 

20 

81.5 

72.0 

76.6 

2.0 

91 

86.0 

72.5 

78.0 

8.0 

87 

324 


NICARAGUA  CANAL  COMMISSION 


TEMPERATURE  AND  RELATIVE  HUMIDITY  AT  CAMP  SABALOS.  1899.— Continued. 


Day 

• 

February. 

March. 

Max. 

Mln. 

Mean. 

] 

Mean 
t-t'. 

Relative 
humidit]) 

r 

■ 

Max. 

Min. 

Mean. 

Mean 
t-t'. 

Relative 
humidity. 

21 

83.0 

71.0 

76.5 

2.0 

91 

87.0 

72.0 

78.5 

4.0 

83 

22 

83.0 

70.0 

76.5 

3.0 

87 

84.5 

72.0 

77.5 

3.0 

87 

23 

86.0 

71.0 

78.0 

3.5 

85 

87.0 

72.0 

78.5 

4.0 

83 

24 

80.0 

72.0 

76.0 

2.5 

89 

86.0 

68.0 

77.5 

5.0 

78 

25 

88.0 

72.0 

76.5 

2.5 

89 

87.5 

72.0 

78.5 

4.0 

83 

26 

83.5 

68.5 

76.5 

3.0 

87 

88.0 

69.0 

77.5 

4.0 

83 

27 

83.0 

71.0 

76.5 

3.0 

87 

86.5 

72.5 

78.5 

4.0 

83 

28 

0 

82.0 

71.0 

76.5 

3.5 

85 

88.0 

72.0 

79.5 

5.0 

79 

29 

•   •   •   ■ 

•   •    •   • 

•    •   •   • 

• 

•   ■   ■ 

•    a 

•   • 

88.5 

73.5 

80.0 

4.5 

81 

80 

•   •   •   • 

•   •   •  • 

•    •   •   • 

• 

•   •   • 

•    • 

•   • 

90.0 

72.0 

80.5 

5.5 

77 

31 

•   ■   •    • 

■   •   •    • 

•    •   •   • 

• 

•   •    • 

•     a 

■   • 

•   •   ■    • 

•    •   •   • 

•  . . . . 

•   •   ■    • 

•   •   •   • 

TEMPERATURE  AND  RELATIVE  HUMIDITY  AT 

SAN  CARLOS  RIVER  STATION. 

Month. 

Temperature. 

Mean 

relative 

humidity 

• 

Month. 

Tbm 

PERATURE. 

Mean 

relative 

humidity. 

Max. 

Min.             Mean. 

Max. 

Min. 

Mean. 

1898. 

1898. 

January . 

...     86 

69                 75.8 

92.0 

May  . 

95 

72 

80.7 

88.5 

February 

...      89 

66                74.5 

88.1 

June . 

93 

73 

79.9 

87.2 

March.. . , 

...      88 

68                 77.0 

86.8 

July  . 

88 

71 

77.6 

89.3 

April  . . . . 

...     91 
TEMPE 

!RA1 

70                77.6 

86.5 

August 

88 

72 

78  0 

89.2 

^URE  AND  RELATIVE  HUMIDITY  AT  SAN  CARLOS  RIVER  STATION,  1898 

• 

Day. 

January. 

February. 

Max. 

Mln.            Mean. 

Mean 
t— t. 

Relative 
humidity. 

r 

Max. 

Min. 

Mean. 

Mean 
t-t. 

2.0 

Relative 
humidity. 

1.!.... 

•   •   ■   • 

•   •••                           •••• 

•   •   • 

•     •     ■ 

78.0 

71.0 

74.0    . 

91 

2 

•   •   •   • 

•   •••                           •••• 

■   •   •   • 

•     •     • 

72.0 

69.0 

70.3 

1.2 

95 

8 

■   *   •   • 

•    •■•                           •••• 

•   •   • 

■     •     • 

76.5 

69.0 

72.3 

0.8 

95 

4 

•   •   •   • 

•    •■•                           •••• 

■   *   •   • 

•     •     • 

73.0 

69.5 

71.0 

0.7 

98 

5 

•   •   •   • 

•    •••                          •••• 

»   •   •   • 

*    •     • 

76.5 

68  0 

71.3 

2.0 

91 

6 

•   •   •  • 

<    •   •   ■                          •   •   •   • 

■   •   •   ■ 

•    •     • 

80.0 

71.0 

74.3 

8.2 

86 

7 

•   •  •   • 

•   ■••                          *••• 

ft   •   •   • 

•     •    • 

80.0 

66.0 

74.6 

8.3 

84 

8 

•   •   *   • 

•    •••                           •   •   •  • 

•   •   • 

•     •     • 

87.0 

74.0 

80.0 

5.0 

79 

9 

•   •   •   • 

•    •••                           •••• 

•   •   •   • 

•     •     • 

79.0 

72.0 

'      75.0 

2.0 

91 

10 

•   •   •   • 

•    •••                          ■■•• 

■   •   •   » 

•     •     • 

88.5 

71.0 

77.8 

3.8 

83 

11 

•    •   •   • 

•   ■••                           •••• 

>    •   •   • 

•     •    « 

89.0 

70.0 

77.0 

4.0 

83 

12 

81.0 

75.0             77.3 

2.0 

• 

91 

78.0 

71.0 

73.6 

1.6 

93 

13 

77.5 

74.0             75.3 

1.3 

93 

83.0 

71.0 

75.8 

3.8 

82 

14 

81.0 

76.0             78.0 

2.5 

89 

77.0 

68.0 

72.6 

2.5 

88 

15 

77.0 

74.0             75.0 

1.4 

93 

83.0 

67.0 

76.0 

4.7 

80 

16 

76.0 

74.0             74.6 

0.8 

95 

81.0 

68.0 

73.6 

2.0 

91 

17 

76.0 

74.0             75.0 

1.0 

95 

81.0 

67.0 

73.6 

2.8 

86 

18 

77.0 

73.5             74.8 

1.3 

93 

87.5 

69.0 

77.1 

4.8 

78 

19 

79.0 

73.0             76.3 

1.3 

93 

82.0 

71.0 

75.6 

2.0 

91 

20 

80.5 

» 

75.0             77.1 

1.5 

93 

80.0 

71.0 

74.6 

1.0 

95 

21 

77.0 

73.0             74.6 

1.3 

93 

86.0 

72.0 

.    78.0 

4.0 

83 

22   

80.5 

72.0             76.1 

1.5 

93 

81.0 

72.0 

75.3 

2.3 

89 

28 

86.0 

72.0             78.3 

0.8 

96 

84.0 

68.0 

74.6 

3.6 

84 

24 

81.5 

72.0             77.1 

3.1 

87 

82.0 

71.0 

75.3 

3.0 

87 

25 

79.0 

71.5             75.6 

1  3 

93 

82.0 

69.0 

74.6 

2.3 

88 

26 

79.0 

73  0             76.0 

2.0 

91 

73.0 

70.0 

71.6 

1.6 

93 

27 

81.0 

73.0             76.6 

2.6 

89 

76.0 

70.0 

72.6 

1.3 

93 

28 

80.0 

79.5             74.0 

1.9 

91 

81.0 

71.0 

75.3 

2.7 

89 

29 

80.0 

70.0             74.3 

2.0 

91 

•   ■   •   * 

•   •   •   • 

•    •    m    • 

•   •   •   • 

•    •    ■   ■ 

80 

79.0 

70.5             75.8 

2.5 

89 

•   •  •   • 

•   •   •   « 

•    •    •    • 

•   ■   •   • 

•   •   •   • 

81 

79.0 

74.0             73.5 

1.7 

93 

•   •   •    • 

■   •   ■   • 

•    •    ■     • 

•    •   •    • 

•    •   ■   ■ 

APPENDIX   III.— HYDROGRAPHIC   REPORT 


326 


TEMPERATURE  AND  RELATIVE  HUMIDITY  AT  SAN  CARLOS  RIVER  STATION,  1898. 


Day 


March. 


April. 


1. 
2. 
3. 
4. 
5. 

6. 
7. 

8. 

y. 

10. 

11. 

12. 
13. 
14. 
15. 

16. 
17. 
IH. 
19. 
20. 

21. 
22. 
23. 
24. 
25. 

20. 
27. 
28. 
29. 
30. 
31. 


Max. 


81.0 
86.0 
87.5 
79.0 
82.5 

82.0 
82.0 
80.5 
78.0 
82.0 

82.0 
81.0 
84.0 
84.0 
82.0 

86.0 
84.0 
85.0 
81.0 
8.5.0 

82.0 
88.0 
87.0 
81.0 
78.0 

83.0 
82.0 
82.0 
80.0 
S«.0 
H8.0 


Min. 


71.0 
69.0 
73.0 
75.0 
75.0 

73.0 
72.0 
73.0 
72.0 
73.0 

73.0 
73.0 
71.0 
70.0 
71.0 

72.0 
72.0 
71.0 
70.0 
71.0 

72.0 
73.0 
74.0 
7.5.0 
72.0 

73.0 
72.0 
68.0 
74.0 
7.5.0 
71.0 


Mean. 


75.0 
76.3 
79.5 
77.1 
78.1 

77.1 
76.5 
76.3 
74.8 
76.6 

76.6 
76.0 
77.3 
77.6 
76.6 


78.0 
77.3 
77.3 
76.0 
77.6 

76.0 
78.0 
79.0 
77.8 
74.6 

77.3 
76.3 
75.0 
78.6 
79.6 
79.0 


Mean 
t— t'. 


2.4 
3.2 
3.9 
1.3 
2.1 

2.8 
2.9 
2.2 
1.2 
1.6 

2.6 
2.4 
3.0 
4.0 
3.0 

4.7 
3.3 
8.0 
2.0 
.5.0 

2.4 
3.7 
4.7 
3.0 
1.8 

8.0 
2.0 
1.9 
5.0 
.5.6 
5.4 


Relative 
humidity. 


89 
87 
88 
98 
91 

87 
87 
91 
95 
98 

89 

89 
87 
83 

87 

81 

85 
87 
»1 

78 

89 
85 
81 
87 
98 

87 
91 
91 
79 
77 
77 


Max. 


83.0 
85.0 
82.0 
83.0 
82.0 

82.0 
76.0 
85.0 
88.0 
84.0 

80.0 
81.0 
87.0 
84.0 
90.0 

84.0 
85.0 
80.0 
84.0 
89.0 

89.0 
78.0 
83.0 
85.0 
88.0 

82.0 
8.5.0 
8'.0 
91.0 
86.0 


Min. 


71.0 
71.0 
75.0 
72.0 
72.0 

74.0 
7.5.0 
73.0 
74.0 
74.0 


74.0 
74.0 
73.0 
7.5.0 
72.0 

73.0 
7.5.0 
75.0 
74.0 
71.0 

75.0 
74.0 
75.0 
73.0 
75.0 

75.0 
72.0 
70.0 
7.5.0 
73.0 


Mean. 


77.0 
76.3 
78.0 
76.3 
76.6 

77.3 
7.5.5 
77.6 
78.6 
77.3 

76.3 

4  t.ii 

78.3 
78.0 
78.0 

77.6 
79.3 
76.6 
77.6 

78.6 

80.0 
75.5 
78.0 
77.0 
77.5 

77.5 
77.0 
76.5 
81.0 
79.0 


Mean 
t-t'. 


2.7 
3.8 
2.7 
2.7 
1.3 

2.0 
1.0 
4.3 
4.0 
4.0 

1.7 
2.7 
3.7 
4.4 
5.0 

3.6 
3.3 
2.8 
3.0 
5.0 

4.7 
1.5 
8.5 
8.0 
2.0 

2.0 
3.5 
3.0 
5.5 
3.0 


Relative 
humidity. 


89 
85 
89 
89 
93 

91 
95 
81 
83 
88 

93 

89 
85 
81 
79 

85 
85 
89 
87 
7» 

81 
113 
85 
87 
91 

91 

85 
87 
78 
87 


TEMPERATURE  AND  RELATIVE  HUMIDITY  AT  SAN  CARLOS  RIVER  STATION,  1898. 


TWai 

May. 

ua>.          r 

-1 

Max. 

Min. 

Mean. 

Mean 
t-t'. 

Relative 
humidity. 

1 

83.0 

74.0 

78.5 

1.5 

98.5 

2 

87.0 

72.0 

78.5 

8.8 

87 

3 

89.0 

74.0 

80.5 

5.0 

79.5 

4 

80.0 

73.0 

76.5 

1.5 

93 

o 

88.0 

7.5.0 

80.5 

1.5 

94 

6 

89.0 

79.0 

84.5 

2. 5 

90 

!.•••• 

95.0 

82.0 

88.0 

.5.0 

81 

8 

8'J.O 

80.0 

84.5 

2.5 

90 

9 

93.0 

82.0 

87.0 

8.5  , 

86 

10 

84.0 

81.0 

82.5 

1.0 

96 

11 

82.0 

80.0 

81.0 

1.0 

96 

12 

91  0 

85.0 

87.5 

4.0 

84.5 

13 

92.0 

78.0 

84.5 

8.5 

86 

14 

80.0 

76.0 

77  5 

1.5 

98 

15 

80.0 

74.5 

76.5 

LO 

95 

June. 


Max. 

Min. 

Mean. 

Mean 
t-t'. 

Relative 
humidity. 

84.0 

78.0 

77.5 

1.5 

98 

91.0 

73.5 

81.0 

4.8 

80 

91.0 

75.0 

81.5 

4.5 

82 

90.5 

76.0 

81.5 

4.0 

84 

91.0 

78.5 

83.0 

5.0 

80 

92.5 

78.0 

84.5 

5.0 

80 

89.0 

77.0 

82.0 

8.5 

86 

91.5 

77.5 

82.5 

8.5 

86 

91.0 

77.0 

88.5 

4.5 

82 

91.0 

77.0 

82.6 

4.8 

80 

79.5 

7,5.0 

77.0 

2.0 

91 

89.0 

73.0 

80.5 

3.0 

87.5 

81.0 

76.0 

78.0 

2.2 

91 

81.5 

76.5 

79.0 

2.5 

89 

84.5 

78.0 

80.6 

5.0 

79.5 

326 


NICARAGUA  CANAL  COMMISSION 


TEMPERATURE  AND  RELATIVE  HUMIDITY  AT  SAN  CARLOS  RIVER  STATION,  1898.— Continued. 


May. 


Day. 


e — 

N 

Max. 

Mln. 

Mean. 

Mean 
t-t'. 

Relative 
humidity, 

85.0 

73.5 

78.0 

1.5 

98 

85.0 

74.0 

78.5 

2.5 

89 

83.0 

76.0 

78.5 

2.0 

91 

87.5 

75.5 

79.5 

8.0 

•     87 

85.0 

75.0 

78.5 

2.0 

91 

81.0 

75.0 

77.5 

1.5 

93 

85.0 

74.0 

78.5 

3.0 

87 

78.5 

75.5 

76.5 

1.5 

93 

91.0 

75.0 

82.5 

6.0 

76 

90.0 

76.5 

82.5 

6.5 

74 

89.0 

76.5 

81.5 

4.5 

82 

9L0 

77.0 

81.5 

3.0 

88 

92.0 

77.0 

82.5 

3.5 

86 

83.0 

76.0 

78.6 

2.0 

91 

86.0 

76.0 

80.5 

2.5 

89 

82.0 

76.5 

79.0 

2.0 

91 

June. 

-A_ 


Max. 


Mln. 


Mean. 


Moan 
t-t'. 


Relative 
humidity. 


16, 
17. 
18. 
19. 
20, 

21. 
22. 
23. 
24. 
25. 

26, 
27. 
28. 
29. 
30. 
31. 


89.5 

76.0 

82.0 

4.0 

89.0 

76.5 

81.5 

3.5 

98.0 

75.0 

8L0 

8.0 

89.5 

74.0 

80.5 

8.5 

83.0 

73.0 

76.5 

2.0 

88.0 

74.0 

79.0 

2.5 

85.0 

78.0 

•     78.5 

1.5 

87.0 

74.5 

79.1 

2.5 

80.5 

74.0 

77.0 

1.5 

83.0 

74.0 

77.5 

1.5 

86.5 

74.0 

78.5 

2.3 

77.0 

73.0 

75.5 

1.0 

85.0 

73.0 

77.5 

2.0 

87.0 

73.0    ■ 

79.0 

2.0 

87.5 

74.0 

80.0 

3.0 

84 
86 
88 
86 
91 

89 

93.5 

89 

98 

93 

89 
95 
91 
91 
87 


TEMPERATURE  AND  RELATIVE  HUMIDITY  AT  SAN  CARLOS  RIVER  STATION,  1898. 


Day. 

JUIiY. 

August. 

t 

Max. 

Mln. 

Mean. 

Mean 
t-t'. 

Relative 
humidity. 

Max. 

Mln. 

Mean. 

Mean 
t-t'. 

Relative 
humidity. 

1 

83.0 

76.0 

78.5 

1.5 

93.5 

78.0 

76.0 

77.0 

1.0 

93 

2 

75.5 

78.0 

74.5 

1.0 

95 

77.0 

73.0 

75.0 

1.5 

93 

8 

88.5 

75.5 

79.0 

3.0 

87 

83.5 

73.0 

77.5 

3.0 

87 

4 

81.0 

75.0 

77.5 

2.0 

91 

83.0 

74.5 

77.5 

2.5 

89 

6 

79.5 

73.5 

76.5 

1.5 

93 

87.5 

73.5 

79.0 

3.5 

85 

6 

85.5 

72.5 

78.5 

8.0 

87 

87.5 

73  5 

80.0 

8.5 

85 

7 

a5.o 

73.5 

79.0 

2.5 

89 

77.0 

76.0 

76.5 

1.5 

93 

8 

77.0 

74.5 

76.0 

1.5 

93 

81.0 

74.5 

77.0 

2.5 

89 

9 

82.5 

72.0 

77.5 

2.5 

89 

77.0 

74.0 

75.5 

1.5 

93 

10 

75.0 

73.0 

74.0 

1.5 

93 

88.0 

74.0 

80.5 

8.5 

85.5 

11 

86.5 

73.0 

78.5 

8.0 

87 

83.5 

74.5 

78.5 

2.5 

89 

12 

82.0 

73.0 

78.0 

2.0 

91 

76.0 

74.5 

75.0 

1.0 

95 

13 

88.0 

72.5 

80.0 

3.5 

.       85 

85.0 

73.0 

77.0 

2.5 

89 

14 

86.5 

73.0 

79.5 

8.5 

85 

82.0 

72.0 

77.0 

1.5 

93 

15 

88.0 

74.0 

80.1 

4.0 

83 

81.0 

73.0 

77.0 

2.0 

91 

16 

88.0 

73.5 

80.1 

3.5 

85 

84.0 

73.0 

78.0 

2.5 

89 

17 

82.5 

75.5 

78.6 

2.5 

89 

83.5 

72.5 

78.0 

2.5 

89 

18 

82.0 

76.0 

78.5 

2.0 

91 

87.5 

73.0 

79.5 

4.0 

83 

19 

84.5 

73.0 

78.5 

3.5 

85 

85.0 

73.5 

79.0 

8.5 

85 

20 

75.5 

71.5 

74.0 

1.0 

95 

86.0 

74.0 

79.0 

3.5 

85 

21 

75.0 

73.0 

74.0 

1.5 

93 

84.0 

75.0 

78.0 

2.5 

89 

22 

85.0 

71.5 

77.5 

8.5 

85 

87.0 

73.0 

80.0 

3.5 

85 

28 

79.5 

74.0 

76.5 

1.5 

93 

78.0 

74.0 

76.5 

1.5 

93 

24 

80.0 

74.0 

76.5 

1.5 

98 

81.5 

73.0 

77.5 

2.0 

91 

25 

76.5 

74.0 

75.5 

1.0 

95 

86.5 

75.0 

80.0 

2.5 

89 

26 

80.5 

73.5 

77.0 

1.5 

93 

84.0 

75.0 

79.0 

2.5 

89 

27   

84.5 

78.5 

78.0 

2.5 

89 

86.0 

75.0 

79.5 

3.5 

85 

28 

82.0 

74.0 

78.0 

2-5 

89 

88.0 

73.0 

77.5 

1.5 

93 

29 

81.0 

74.5 

78.0 

2.5 

89 

85.0 

74.0 

79.5 

8.0 

87 

80 

86.0 

74.0 

79.0 

4.0 

83 

84.0 

73.0 

77.5 

2.0 

91 

81    

87.0 

73.0 

80.0 

4.5 

81 

80.0 

74.0 

76.5 

1.5 

98 

APPENDIX  III.— HYDROGRAPHIC   REPORT 


327 


TEMPERATURE  AND  RELATIVE  HUMIDITY  AT  OCHOA  STATION. 


Month. 


Temperature. 


Max. 


1898. 

January 88 

February ....  85 

March 87 

April 88 

May 94 

June 90 

July    89 

August 87 


Min. 


Mean. 


Mean 

relative 

humidity. 


Month. 


66 
66 
67 
66 

72 
71 
70 
71 


78.9 
78.3 
75.1 
75.8 
78.3 
77.5 
76.6 
77.0 


91.6 
90.4 
87.6 
88.8 
90.0 
90.7 
91.5 
91.4 


1898. 
September. . . . 

October 

November .... 
December 

1899. 

January 

February 

March 


Temperature. 

Mean 

relative 

humidity. 

Max. 

Min. 

Mean. 

91 

70 

77.5 

89.6 

95 

71 

78.2 

89.4 

89 

70 

76.1 

92.0 

85 

67 

75.1 

91.0 

84.5 

67 

74.8 

93.2 

86 

68 

75.3 

91.9 

91 

67 

75.6 

89.7 

TEMPERATURE  AND  RELATIVE  HUMIDITY  AT  OCHOA  STATION,  1898. 


Day. 


1. 
2. 
3. 
4. 
5. 

6. 
7. 
8. 
9. 
10. 

11. 
12. 
18. 
14. 
15. 

16. 
17. 
18. 
19. 
20. 

21. 
22. 
28. 
24. 
25. 

26 

27. 

28 

29. 

80. 

81. 


January. 

A 

r 

Max. 

Min. 

Mean. 

Mean 
t— t'. 

Relative 
humidity. 

81.0 

72.5 

75.5 

2.5 

89 

78.5 

69.0 

72.8 

2.8 

87 

76.5 

66.5 

70.8 

1.7 

98 

75.0 

66.5 

70.1 

1.8 

98 

72.5 

68.5 

70.8 

0.4 

98 

74.5 

70.5 

72.8 

0.7 

98 

80.5 

70.5 

74.8 

8.2 

87 

80.5 

70.5 

75.1 

4.6 

80 

79.5 

73.0 

75.6 

2.8 

89 

76.0 

72.5 

74.1 

0.5 

98 

78.5 

.... 

•   «  •   • 

•  ■  •  • 

•  •  •  • 

82.5 

78.0 

76.8 

1.7 

93 

81.5 

72.5 

76.0 

1.4 

93 

78.5 

70.0 

74.8 

1.2 

95 

78.0 

69.5 

78.1 

1.0 

95 

75.0 

72.5 

78.8 

L2 

95 

77.0 

70.5 

78.6 

1.0 

95 

•  ••  ••••  ••••  ••••  ••• 

•  ••  ••■•  •••*  «•••  ••• 

•  a*  ••••  *••*  ••••  ••• 

•  ••  ••*•  ••••  ••••  ••• 

*••  ••••  ••#•  ••••  ••• 


82.5 

72.0 

75.8 

.  2.8 

89 

77.5 

70.5 

74.0 

•       2.5 

88 

78.0 

72.0 

74.6 

1.8 

98 

76.5 

72.0 

78.6 

1.1 

95 

81.0 

72.5 

75.5 

8.0 

87 

79.0 

70.5 

74.0 

2.0 

91 

78.0 

70.0 

78.6 

1.8 

95 

81.5 

71.0 

74.6 

3.8 

82 

•   •   «  • 

69.0 

•   •  •   • 

•   •   •  * 

•   •  •  * 

February. 

Max. 

Min. 

Mean. 

Mean 
t-t'. 

Relative 
humidity. 

74.0 

70.0 

72.5 

1.2 

95 

78.0 

69.0 

71.0 

1.0 

95 

78  0 

70.0 

78.0 

2.2 

91 

76.0 

69.5 

72.0 

1.0 

95 

77.0 

68.5 

72.6 

2.8 

88 

79.5 

68.5 

78.0 

8.7 

84 

80.0 

67.5 

72.6 

3.6 

84 

72.0 

70.0 

71.1 

0.6 

98 

•   •  «   * 

70.5 

»   •  •  • 

•   •  •  • 

•   *   •   • 

76.0 

70.5 

78.5 

2.7 

88 

81.5 

72.0 

75.6 

2.8 

89 

76.0 

71.0 

73.0 

1.4 

93 

81.0 

69.5 

74.8 

8.5 

84 

75.5 

69.5 

71.6 

1.6 

93 

82.0 

67.0 

78.6 

3.6 

84 

72.0 

71.0 

71.6 

0.8 

95 

77.0 

66.5 

71.6 

1.5 

98 

84.5 

67.5 

75.1 

3.1 

87 

82.5 

72.0 

76.1 

2.8 

87 

82.5 

71.0 

75.1 

1.5 

93 

83.5 

72.0 

76.8 

8.3 

86 

80.5 

71.0 

74.3 

1.8 

91 

81.0 

67.5 

73.8 

2.7 

88 

81.0 

70.0 

74.3 

2.7 

88 

78.5 

69.5 

78.5 

1.9 

91 

76.0 

70.5 

72.3 

0.8 

95 

74.0 

70.5 

71.8 

0.7 

98 

80.5 

69.5 

74.1 

2.3 

88 

328 


NICARAGUA   CANAL  COMMISSION 


TEMPERATURE  AND  RELATIVE  HUMIDITY  AT  OCHOA  STATION.  1898. 


March. 

April. 

Day. 

r 

^ 

Max. 

Min. 

Mean. 

Mean 
t-t'. 

Relative 
humidity. 

Max. 

Min. 

Mean. 

Mean 
t-t'. 

Relative 
humidity. 

1 

80.0 

71.5 

74.8 

2.2 

91 

83.0 

68.5 

75.0 

2.5 

88 

8 

H2.0 

68.5 

74.6 

2.8 

86 

84.0 

69.5 

75.0 

8.4 

84 

3 

86.5 

69.5 

77.1 

2.8 

87 

82.0 

67.5 

74.6 

2.2 

91 

4 

76.0 

74.0 

75.0 

0.9 

95 

81.5 

78.0 

76.1 

2.0 

91 

5 

79.5 

73.5 

75.6 

1.3 

93 

82.0 

73.0 

76.5 

0.7 

98 

6 

78.0 

71.0 

74.0 

1.9 

91 

•   •   •   • 

74.5 

•   •   •   • 

.... 

•   •   *   • 

7 

•   •   •    ■ 

70.5 

•   •   •   • 

•   •   •   * 

•   •   •   • 

78.5 

74.0 

75.6 

0.5 

98 

8 

79.5 

72.5 

74.8 

1.8 

91 

83.5 

70.5 

75.8 

3.8 

82 

9 

78.0 

70.5 

74.1 

1.1 

95 

83.5 

68.0 

75.0 

3.9 

80 

10 

79.0 

71.5 

74.8 

2.0 

91 

81.5 

71.5 

7.5.6 

2.8 

87 

11 

83.5  ' 

71.5 

76.1 

3.6 

85 

81.0 

72.5 

76.0 

2.0 

91 

12 

80.5 

71.5 

74.8 

2.3 

89 

85.0 

73.5 

77.6 

2.5 

89 

18 

86.5 

69.5 

76.0 

4.0 

82 

85.5 

73.5 

77.5 

4.0 

82 

14 

•    •   •   ■ 

68.0 

•  «   •   • 

•    ■   ■   • 

■    •   •   • 

84.0 

70.0 

75.3 

3.5 

85 

15 

82.0 

70.0 

75.8 

2.2 

91 

86.0 

68.0 

75.1 

4.0 

82 

16 

82.5 

70.5 

75.6 

2.8 

87 

88.0 

66.5 

75.5 

3.5 

84 

17 

83.5 

70.5 

75.3 

4.8 

81 

82.5 

70.5 

76.3 

1.5 

93 

18 

82.5 

68.5 

74.1 

3.6 

84 

79.5 

72.5 

7.5.8 

1.2 

95 

19   

85.0 

67.0 

74.8 

4.3 

80 

8.5.0 

72.0 

76.6 

2.6 

89 

80 

8.5.0 

68.0 

75.0 

4.9 

78 

85.0 

68.5 

75.5 

4.0 

82 

21 

82.0 

71.0 

75.0 

2.2 

91 

80.0 

71.5 

74.5 

1.9 

91 

22 

81.0 

71.5 

74.8 

2.2 

91 

78.0 

72.0 

74.3 

1.2 

95 

28 

86.5 

69.0 

76.0 

4.0 

82 

86.0 

72.5 

77.3 

2.5 

89 

24 

82.5 

71.0 

76.1 

2.5 

89 

85.5 

73.0 

77.8 

2.7 

89 

25 

•   ■  •   • 

72.0 

•    ■   •   • 

■   •   ■   • 

•   •  •  • 

85.5 

72.0 

77.5 

4.2 

83 

26 

82.0 

71.5 

76.0 

3.0 

89 

81.5 

71.0 

75.0 

1.5 

98 

27 

73.0 

71.0 

72.0 

1.7 

93 

80.0 

70.5 

74.1 

0.8 

95 

28 

82.5 

68.0 

74.1 

2.5 

88 

80.5 

68.0 

74.0 

1.7 

93 

29 

83.0 

70.0 

75.3 

3.0 

87 

87.5 

69  5 

76.8 

4.3 

80 

30 

84.0 

67.0 

74.6 

5.0 

78 

85.0 

70.0 

77.1 

1.1 

95 

31 

83.5 

70.0 

75.6 

3.0 

87 

.... 

•    •   •   • 

•   •   •    ■ 

•   ■    •   • 

•    ■   •    • 

TEMPERATURE  AND 

RELATIVE  HUMIDITY  AT  OCHOA  STATION.  1898. 

» 

May. 

» 

June. 

Day. 

Max. 

Min. 

Mean. 

Mean 

Relative 
humidity. 

Max. 

Min. 

Mean. 

Mean 
t-t'. 

Relative 
humidity. 

1 

83.0 

74.0 

77.6 

1.5 

93 

80.5 

73.5 

76.8 

1.2 

95  • 

2 

82.0 

72.5 

76.5 

1.2 

95 

87.0 

71.5 

77.5 

4.5 

80 

3 

88.0 

75.0 

79.6 

8.5 

85 

86.0 

71.5 

77.5 

3.0 

87 

4 

75.0 

72.0 

73.8 

0.2 

98 

84.5 

73.5 

77.6 

2.5 

89 

5 

83.0 

73.0 

77.0 

1.7 

93 

87.5 

75.0 

79.8 

3.8 

85 

6 

85.5 

73.5 

78.5 

1.9 

91 

90.0 

75.0 

81.5 

3.2 

88 

7 

89.0 

74.0 

79.8 

2.8 

87 

86.5 

75.0 

79.8 

2.7 

89 

8 

87.5 

76.5 

80.3 

3.2 

87 

85.5 

75.5 

79.0 

2.9 

87 

9 

88.0 

75.0 

80.1 

4.1 

83 

86.5 

76.0 

80.1 

2.8 

87 

10 

80.0 

74.5 

77.1 

0.8 

95 

87.0 

75.5 

80.1 

2.6 

89 

11 

80.0 

75.5 

77.3 

0.5 

98 

82.0 

72.5 

76.8 

1.7 

93 

12 

87.0 

73.0 

78.8 

2.7 

89 

84.5 

71.5 

77.5 

1.4 

93 

13 

85.5 

74.0 

78.6 

2.5 

89 

79.5 

74.0 

76.0 

1.0 

95 

14 

84.0 

74.5 

78.0 

1.9 

91 

77.0 

73.0 

74.8 

1.5 

93 

15 

79.5 

73.5 

76.1 

1.1 

95 

81.0 

72.5 

76.6 

1.8 

93 

APPENDIX  III.— HYDROGRAPHIC   REPORT 


329 


TEMPERATURE  AND  RELATIVE  HUMIDITY  AT  OCHOA  STATION.  1898.— Continued. 


May. 

June. 

• 

Day. 

Max. 

Mln. 

Mean. 

Mean 
t-t'. 

Relative 
humidity. 

Max. 

Mln. 

Mean. 

Mean 
t-t'. 

Relative 
humidity. 

16 

84.5 

78.5 

78.1 

2.1 

91 

84.0 

75.0 

78.8 

1.3 

94 

17 

85.0 

74.0 

78.3 

2.2 

91 

87.0 

75.0 

79.5 

2.5 

89 

18 

82.5 

73.5 

77.1 

1.6 

93 

87.0 

73.0 

78.5 

1.4 

93 

19 

90.5 

78.0 

79.1 

8.5 

85 

87.5 

72.5 

78.1 

2.8 

87 

20 

82.5 

72.5 

76.1 

1.6 

98 

81.0 

78.0 

76.0 

2.0 

91 

21 

84.0 

73.0 

77.5 

1.9 

91 

84.5 

73.0 

77.1 

2.1 

91 

22 

88.0 

73.5 

79.0 

8.3 

87 

84.5 

73.0 

77.5 

2.0 

91 

23 

77.5 

78.0 

75.3 

1.0 

95 

77.0 

73.5 

75.0 

0.7 

93 

24 

92.0 

73.5 

80.8 

4.3 

82 

78.0 

73.5 

75.3 

0.8 

95 

25 

93.5 

72.0 

81.1 

4.6 

82 

83.0 

73.5 

77.1 

1.6 

93 

26 

93.5 

73.5 

81.3 

3.8 

84 

84.0 

73.5 

77.0 

1.7 

93 

27 

88.5 

73.0 

78.6 

3.0 

87 

77.0 

72.0 

74.5 

0.7 

98 

28 : 

92.0 

72.5 

80.0 

2  7 

89 

80.5 

72.5 

75.5 

1.4 

98 

29 

87.5 

75.5 

79.5 

2.3 

91 

83.0 

71.5 

76.1 

2.3 

89 

80 

87.0 

75.5 

80.1 

2.6 

89 

85.5 

72.5 

78.0 

3.0 

87 

81 

82.0 

75.5 

77.8 

2.3 

89 

■   •   •    • 

•   •   •   • 

•   •  •   « 

.... 

•   •   •    • 

TEMPERATURE  AND  RELATIVE  HUMIDITY  AT  OCHOA  STATION,  1898. 


July. 

August. 

JL 

Day. 

Bfax. 

Min. 

Mean. 

Mean 

t-tr. 

Relative 
humidity. 

Max. 

Min. 

Mean. 

'Mean 

tr-t\ 

Relative 
humidity. 

1 

•   •   •   • 

73.0 

«  •  ■   • 

•  •  •  • 

•  •   •   • 

79.5 

76.0 

77.1 

1.3 

93 

2 

76.5 

72.0 

74.6 

0-8 

98 

76.5 

72.5 

74.0 

0.7 

98 

3 

82.5 

72.5 

77.1 

2.1 

91 

81.5 

72.5 

76.3 

1.8 

91 

4 

80.5 

74.5 

76.6 

1.6 

93 

83.5 

73.5 

77.1 

2.3 

89 

5 

81.0 

72.5 

75.5 

1.3 

93 

84.0 

73.0 

77.6 

2.5 

89 

6 

86.0 

72.0 

78.0 

2.0 

91 

85.0 

73.0 

78.3 

2.3 

89 

7 

85.0 

73.0 

78.3 

2.7 

89 

75.5 

75.0 

75.1 

0.6 

98 

8 

89.0 

73.5 

78.6 

l.l 

96 

83.5 

74.0 

77.3 

2.3 

89 

9 

81.5 

71.5 

76.5 

2.4 

89 

76.5 

74.0 

75.0 

0.5 

98 

10 

77.0 

72.5 

74.1 

l.l 

95 

85-5 

73.5 

79.0 

2.7 

89 

11 

84.5 

72.5 

77.0 

2.2 

91 

76.0 

74.0 

75.3 

0.5 

98 

12 

87.0 

73.0 

79.1 

2.8 

87 

78.5 

74.5 

75.8 

0.7 

98 

13 

88.0 

73.5 

79.5 

3.2 

87 

83.5 

72.0 

76.0 

2.9 

87 

14 

86.0 

74.0 

78.8 

3.0 

87 

83.5 

71.0 

76.3 

3.3 

85 

15 

87.0 

73.0 

78.3 

3.3 

85 

81.5 

72.5 

76.5 

1.7 

93 

16 

85.0 

72.5 

78.0 

2.4 

89 

84.0 

73.5 

77.3 

2.7 

89 

17 

80.0 

75.0 

77.0 

1.5 

98 

80.0 

72.0 

75.3 

1-3 

95 

18 

80.0 

73.5 

76.3 

l.O 

95 

85.0 

71.5 

77.1 

3.3 

85 

19 

83.0 

72.0 

76.6 

2.6 

89 

85.5 

71.5 

78.0 

3.0 

87 

20 

79.0. 

70.5 

74.5 

2.5 

88 

86.0 

73.5 

78.5 

3.4 

85 

21 

79.5 

71.5 

74.3 

2.3 

88 

80.5 

73.5 

76.0 

1.9 

91 

22 

81.0 

70.0 

74.8 

1.8 

91 

86.0 

72.5 

78.0 

8.0 

87 

23 

78.5 

72.5 

75.1 

1.1 

95 

76.5 

73.0 

74.8 

0.3 

98 

24   ..... 

78.5 

73.5 

75.1 

0.8 

95 

83.0 

73.0 

77.0 

1.3 

95 

25 

75.5 

73.0 

74.1 

0.3 

98 

87.0 

75.0 

79.3 

8.0 

87 

26 

75.5 

73.0 

74.5 

0.5 

98 

84.0 

74.5 

78.1 

3.8 

89 

27 

83.0 

71.5 

76.3 

2.5 

89 

81.0 

74.0 

70.6 

1.6 

93 

28 

82.5 

73.5 

77.3 

2.0 

91 

83.0 

72.5 

77.1 

8.5 

89 

29 

8L0 

73.0 

76.6 

1.8 

93 

80.0 

74-0 

76.6 

1.1 

95 

80 

79.0 

74.0 

76.3 

1.2 

95 

83.0 

72.5 

77  1 

3.0 

91 

31 

87.0 

73.0 

79.3 

3.0 

87 

80.5 

74.0 

77.0 

1.0 

95 

330 


NICARAGUA  CANAL  COMMISSION 


TEMPERATURE  AND  RELATIVE  HUMIDITY  AT  OCHOA  STATION.  1898. 


September. 

October. 

Day. 

/ — 
Max. 

Mln. 

Mean. 

Mean 
t-t'. 

Relative 
humidity. 

Max. 

Miu. 

Mean. 

Mean 
t-t'. 

Bolative 
humidity. 

1 

79.5 

71.5 

74.8 

1.1 

95 

95.0 

74.0 

81.0 

8.0 

88 

a 

86.0 

71.0 

78.8 

2.7 

89 

88.0 

72.0 

79.0 

4.0 

83 

8 

•   •   •   • 

75.0 

■   •  •   ■ 

.... 

•   «   •   • 

84.0 

74  0 

78.0 

3.5 

89 

4 

81.0 

74.0 

76.6 

1.0 

95 

84.0 

72.0 

77.0 

2.5 

89 

5 

86.0 

73.0 

78.3 

3.4 

89 

78.0 

73.0 

75.0 

1.5 

93 

rt 

88.0 

78.5 

77.6 

1.4 

98 

85.0 

71.0 

78.0 

2.5 

89 

7 

79.0 

74.0 

76.8 

1.5 

98 

90.0 

73.0 

80.0 

4.0 

83 

8 

77.0 

73.5 

75.0 

1.3 

95 

90.0 

75.0 

81.0 

3.0 

88 

9 

85.5 

73.5 

78.0 

8.2 

87 

90.0 

73.0 

80.0 

3  5 

8.5 

10 

86.5 

72.5 

77.5 

8.0 

87 

91.0 

72.0 

80.0 

3.5 

85 

11 

88.5 

71.0 

77.0 

3.5 

89 

92.0 

78.0 

81.0 

4.0 

84 

12 

87.5 

72.0 

78.0 

3.0 

87 

86.0 

72.0 

78.0 

2.5 

89 

13 

70.0 

70.5  • 

74.3 

1.3 

98 

81.0 

74.0 

77.0 

1.5 

•      93 

14 

76.5 

71.5 

74.6 

0.8 

95 

78.0 

72.0 

75.0 

1.5 

93 

15 

86.5 

78.5 

79.8 

3.3 

85 

78.0 

78.0 

76.0 

1.0 

95 

16 

87.5 

73.5 

79.6 

8.8 

88 

86.0 

74.0 

79.0 

3.0 

91 

17 

87.5 

78.0 

79.8 

4.8 

81 

87.0 

74.0 

79.0 

8.0 

87 

18 

85.5 

74.5 

79.1 

3.1 

87 

88.0 

72.0 

77.0 

8.0 

87 

1» 

88.0 

75.0 

77.8 

2.8 

87 

89.0 

73.0 

80.0 

2.5 

89 

30 

84.5 

78.5 

77.6 

2.8 

87 

87.0 

74.0 

80.0 

3.5 

89 

21 

85.0 

73.0 

77.6 

2.8 

87 

90.0 

73.0 

78.0 

8.0 

87 

23   

85.0 

72.0 

76.5 

8.2 

87 

86.0 

74.0 

80.0 

2.5 

89 

23 

88.0 

71.0 

76.3 

1.7 

98 

77.0 

75.0 

76.0 

0.5 

98 

24 

•   •   •    • 

71.5 

*   ■   •   • 

• . . . 

•   •   •   • 

83.0 

78.0 

77.0 

2.0 

91 

25   

86.0 

73.0 

77.3 

2.2 

91 

77.0 

74.0 

75.0 

1.0 

95 

26 

74.5 

73.0 

73.7 

0.7 

98 

78.0 

73.0 

75.0 

1.0 

95 

27 

88.0 

72.5 

78.5 

3.0 

87 

85.0 

73.0 

78.0 

3.0 

91 

28 

88.0 

72.0 

80.0 

2.5 

89 

85.0 

73.0 

78.0 

2.5 

89 

29 

91.0 

75.0 

81.0 

2.5 

90 

90.0 

72.0 

80.0 

3.5 

85 

80 

91.0 

78.0 

81.0 

2.5 

90 

79.5 

78.5 

76.0 

1.2 

95 

81 

•   •   •   • 

•   •   •   • 

•   •   •   * 

*   •   •  • 

•   •  •   * 

89.5 

72.5 

80.0 

3.9 

87 

TEMPERATURE  AND  RELATIVE  HUMIDITY  AT  OCHOA  STATION,  1898. 


November. 

Day. 

Max. 

Mln. 

Mean. 

Mean 
t-t'. 

Relative 
humidity. 

1 

89.0 

74.0 

79.6 

3.3 

85 

3 

87.5 

70.0 

78.6 

8.5 

•     85 

3 

86.0 

71.5 

77.8 

3.8 

87 

4 

81.0 

73.0 

76.6 

1.0 

95 

5 

88.0 

73.5 

77.8 

1.8 

91 

6 

77.5 

74.5 

75.5 

0.9 

95 

7 

79.0 

73.5 

76.0 

0.9 

95 

O  •  •  •  •  • 

80.0 

74.5 

76.6 

1.8 

91 

9 

78.5 

73.5 

75.5 

1.3 

95 

10 

76.5 

73.5 

75.0 

0.7 

98 

11 

82.0 

73.5 

77.1 

3.0 

91 

13 

80.5 

74.0 

77.8 

1.0 

95 

18 

75.5 

74.0 

74.6 

0.8 

95 

14 

8.3.0 

73.0 

77.0 

3.3 

91 

15 

78.5 

73.0 

75.1 

1.1 

95 

Max. 


December. 


Mki. 


Mean. 


77.5 

78.0 

75.0 

88.5 

73.5 

78.0 

84.5 

73.0 

77.5 

83.0 

75.0 

78.0 

83.5 

73.0 

75.5 

77.5 

73.5 

75.0 

83.5 

71.5 

76.0 

79.0 

73.5 

75.0 

81.0 

71.5 

75.5 

78.0 

73.0 

74.5 

76.0 

70.5 

73.5 

84.5 

70.0 

76.0 

77.0 

71.5 

73.5 

88.5 

67.5 

74.5 

88.0 

67.5 

74.5 

Mean 
t-f. 


1.0 
2.0 
2.8 
2.0 
1.5 

1.0 
2.5 
1.5 
1.0 
1.0 

0.5 
2.6 
1.0 
8.0 
2.5 


Relative 
humidity. 


95 
91 
89 
91 
98 

95 
89 
98 
95 
95 

98 
89 
95 
86.5 

88.5 


APPENDIX   III.— HYDROGRAPHIC   REPORT 


331 


TEMPERATURE  AND  RELATIVE  HUMIDITY  AT  OCHOA  STATION,  1898.— Continued. 


November. 

1 

December. 

Day. 

Max. 

Min. 

Mean. 

Mean 
t— t'. 

Relative 
humidity. 

Max. 

Min. 

Mean. 

Mean 
t-t'. 

Relative 
humidity. 

16 

73.5 

73.0 

73.1 

0.3 

98 

79.5 

71.0 

74.5 

1.5 

93 

17 

76.0 

72.5 

73.8 

0.8 

95 

82.0 

70.0 

74.5 

2.0 

91 

18 

74.0 

72.5 

73.1 

0.6 

98 

78.5 

69.5 

73.5 

1.0 

95 

19 

82.0 

72.5 

75.8 

2.8 

89 

85.0 

68.5 

75.5 

3.0 

87 

20 

77.0 

71.0 

78.8 

1.7 

93 

84.0 

.68.5 

75.0 

2.0 

91 

21 

-'    84.0 

70.5 

76.0 

3.2 

87 

84.0 

69.5 

75.5 

2.5 

89 

22 

83.5 

71.5 

76.3 

2.7 

89 

83.0 

68.0 

75.0 

2.5 

89 

23 

81.0 

70.0 

75.0 

2.5 

89 

84.0 

70.0 

76.0 

3.0 

87 

24 

80.5 

72.0 

75.1 

1.5 

98 

83.0 

67.0 

74.0 

2.5 

88 

25 

80.5 

72.0 

75.8 

2.0 

91 

• 

88.5 

67.5 

75.0 

2.5 

89 

20 

84.0 

72.5 

77.3 

2.0 

91 

83.0 

70.5 

75.0 

2.5 

89 

27 

88.5 

73.5 

77.5 

1.7 

93 

80.0 

67.0 

73.5 

'    2.0 

91 

28 

82.5 

78.5 

77.5 

2.0 

91 

82.0 

68.0 

75.0 

2.5 

89 

29 

82.0 

74.5 

77.1 

1.8 

91 

82.0 

68.5 

75.0 

2.0 

91 

80 

82.0 

71.5 

75.8 

2.5 

89 

82.0 

71.0 

76.5 

2.0 

91 

31 

«   •   •   • 

•   •   ■   • 

•   •   •   ■ 

•  •   ■   • 

.... 

82.0 

71.5 

76.0 

2.0 

91 

TEMPERATURE  AND  RELATIVE  HUMIDITY  AT  OCHOA  STATION,  1899. 

January. 

February. 

Day. 

^^^ 

^ 

r 

Max. 

Min. 

Mean. 

Mean 
t-t'. 

Relative 
humidity. 

Max. 

Min. 

Mean. 

Mean 

t-t'. 

Relative 
humidity. 

1 

80.0 

71.5 

75.0 

1.0 

95 

78.5 

72.5 

74.5 

1.0 

95 

2 

81.0 

72.0 

75.5 

1.5 

93 

83.5 

69.0 

75.0 

2.5 

89 

3 

81.5 

72.0 

75.5 

1.5 

98 

82.0 

71.0 

75.5 

2.0 

91 

4 

79.0 

71.0 

75.0 

1.5 

93 

80.0 

71.5 

75.5 

2.0 

91 

5 

79.0 

71.5 

74.5 

1.5 

93 

81.0 

70.5 

75;0 

2.0 

91 

6 

79.0 

70.5 

74.0 

1.5 

93 

80.0 

70.5 

74.5 

1.0 

95 

7 

77.0 

71.0 

73.5 

1.5 

93 

83.5 

71.0 

76.0 

2.0 

91 

8 

77.5 

69.5 

73.0 

1.0 

95 

86.0 

71.0 

77.0 

2.0 

91 

9 

81.0 

70.0 

75.5 

1.5 

93 

88.0 

72.0 

76.0 

2.5 

89 

10 

80.5 

71.5 

75.5 

1.5 

93 

79.0 

71.5 

75.0 

1.5 

93 

11 

77.5 

72.0 

74.0 

1.0 

95 

76.0 

71.0 

74.0 

0.5 

98 

12 

75.5 

72.5 

74  0 

0.5 

98 

76.0 

73.0 

74.5 

0.5 

98 

13 

82.5 

72.0 

76.5 

1.5 

93 

78.0 

71.0 

73.5 

2.0 

91 

14 

78.0 

72.0 

74.5 

1.0 

95 

73.5 

69.5 

71.0 

1.5 

93 

15 

80.5 

72.0 

75.5 

1.0 

95 

78.0 

68.0 

72.5 

1.0 

95 

16 

79.0 

72.0 

75.0 

1.5 

93 

79.0 

68.5 

73.5 

1.5 

93 

17 

80.0 

71.0 

75.0 

1.0 

95 

80.0 

70.0 

74.5 

1.5 

93 

18 

78.5 

72.5 

75.0 

1.0 

95 

78.0 

•  72.0 

75.0 

1.0 

95 

19 

80.0 

72.0 

75.5 

1.5 

93 

82.5 

72.0 

75.5 

2.0 

91 

20....... 

76.5 

70.5 

73.5 

1.0 

95 

83.0 

71.0 

76.5 

2.5 

89 

21 

79.0 

70.5 

74.0 

1.5 

93 

81.5 

72.0 

76.0 

1.5 

93 

22 

81.0 

70.0 

73.5 

1.5 

93 

83.0 

72.5 

77.0 

2.5 

89 

28 

81.5 

71.5 

76.0 

2.0 

91 

83.0 

72.0 

76.5 

2.5 

89 

24 

81.0 

72.5 

75.5 

l.O 

95 

80.0 

71.0 

75.0 

1.5 

93 

25 

79.0 

72.0 

75.0 

1.5 

93 

82.0 

71.0 

76.5 

2.5 

89 

26 

83.0 

70.5 

75.5 

2.0 

91 

83.0 

71.5 

76.5 

2.0 

91 

27 

84.5 

69.5 

76.0 

2.0 

91 

88.0 

72.5 

76.5 

2.5 

89 

28 

88.5 

69.0 

75.0 

2.5 

89 

83.0 

72.0 

76.5 

2.5 

89 

29 

79.0 

69.0 

74.0 

1.5 

98 

■   •   ■   • 

•    •   •   • 

«   •   •    • 

•    •   •   • 

•   •    •    • 

30 

84.0 

68.5 

75.0 

3.0 

87 

•    •   •   • 

•   •   •   • 

•   •   •   « 

*   *   •   • 

•   •   •    ■ 

31 

79.5 

67.0 

73.5 

2.0 

91 

•   •   «   • 

•   •   • 

•    •    *    a 

•   •   •   ■ 

•   •   •   • 

332 


NICARAGUA   CANAL  COMMISSION 


TEMPERATURE  AND  RELATIVE  HUMIDITY  AT  OCHOA  STATION.  1899. 


March. 

Day. 

Max. 

Min. 

Mean. 

Mean 
t-t'. 

Relative 
humidity. 

Day. 

Max. 

Min. 

Mean. 

Mean 
t-t. 

Relative 
humidity. 

1 

.      77.0 

70.0 

72.5 

1.0 

95 

17 

81.5 

71.0 

75.0 

1.5 

93 

2 

.      82.0 

08.0 

74.0 

1.5 

98 

18 

81.5 

70.5 

75.0 

1.5 

93 

3 

.      79.0 

71.0 

74.0 

1.0 

95 

19 

91.0 

70.5 

79.0 

1.5 

93 

4 

.      85.0 

70.0 

76.0 

2.0 

91 

20 

88.5 

70.5 

78.0 

4.0 

83 

5 

.      80.5 

69.5 

76.5 

2.5 

89 

21 

88.0 

71.0 

78.5 

4.5 

81 

6 

.     84.0 

70.5 

76.0 

2.5 

89 

22 

81.5 

71.5 

76.0 

8.5 

85 

7 

.      78.0 

09.0 

71.5 

0.5 

98 

28 

86.0 

70.0 

76.0 

3.0 

87 

8 

.      78.0 

09.0 

72.5 

0.5 

98 

24 

85.5 

69.5 

76.0 

3.0 

87 

» 

.      82.5 

69.5 

74.5 

2.0 

91 

25 

86.5 

68.5 

76.0 

5.0 

78 

10 

.      83.0 

08.0 

74.0 

2.5 

88 

26 

84.5 

68.0 

75.5 

4.0 

83 

11 

.      84.5 

07.0 

74.5 

3.0 

86 

27   

84.0 

72.5 

77.0 

3.0 

87 

13 

.      78.0 

72.0 

74.5 

1.0 

95 

28 

86.0* 

70.5 

77.0 

4.0 

83 

13 

.      80.0 

72.0 

75.5 

1.0 

95 

29 

80.5 

71.0 

77.0 

4.0 

83 

14 

.      70.0 

78.0 

74.0 

1.5 

95 

30 

84.5 

70.5 

76.5 

2.5 

89 

15 

.      87.0 

72.5 

77.5 

1.5 

93 

31 

80.0 

73.0 

76.0 

1.5 

98 

10 

.     88.0 

72.0 

76.0 

2.0 

91 

TEMPERATURE  AND  RELATIVE  HUMIDITY  AT  CAMP  BARTON  ON  RIO  DESEADO. 


Month. 


Tbmpekature. 


Max. 


Min. 


1898. 

January 86 

February 84 

March 87 

April 87 

May   91 

June 86 


65 
60 
68 
67 
^  72 
73 


Mean. 


74.1 
74.1 
77.2 
78.8 
79  5 
78.9 


'  Mean 
relative 
humidity. 


94.7 
90.2 
84.7 
85.2 
89.4 
91.0 


Tbm^rkature. 


Month. 


Max. 


1898. 
July  ...    . 
August. . . 
September 
October  . . , 
November  . 
December  . 


85 
87 
91 

«9 
88 
84 


Min. 


73 
73 
73 
72 
71 
66 


Mean. 


78.1 

iO.O 

79.8 
79.5 
76.8 
76.1 


Mean 

relative 

humidity 


92.1 
91.8 
86.8 
88.8 
94.3 
94.0 


TEMPERATURE  AND  RELATIVE  HUMIDITY  AT  CAMP  BARTON  ON  RIO  DESEADO.  1898. 

Obseryations  taken  at  7  A.  M.,  12  M.  and  7  P.  M. 


Day. 


Max. 


1 81 

2 71 

3 70 

4 70 

5 76 

6 77 

7 78 

8 82 

9 79 

10 

11 

12 86 

18 82 

14 88 

15 74 


Min. 


71 
69 
65 
65 
67 

72 
70 
69 
72 


71 
71 
68 
69 


January. 

A 


Mean. 

76 
70 
68 
69 
72 

75 
75 
76 
76 


78 
76 
77 
72 


Moan 
t-t'. 


1.5 
1.5 
0.5 
1.0 
0.5 

0.5 
1.5 
4.0 
1.5 


2.5 
1.0 
3.5 
0.5 


Restive 
humidity. 


93 
93 
98 
95 
98 

98 
93 
82 
93 


89 
95 

85 
98 


Max. 


76 
74 
74 
75 
75 

81 
79 
74 
81 
79 

81 
80 
80 
78 
82 


Min. 


71 
70 
69 
69 
75 


68 
66 
69 
70 
70 

70 
70 
69 
69 
66 


February. 


Mean. 


78 
72 
71 
72 
71 


74 
74 
72 
74 
74 

76 
75 
75 
74 
75 


Mean 
t-t'. 


Relative 
humidity, 


0.0 

100 

0.5 

98 

0.0 

100 

0.5 

98 

1.5 

95 

4.0 

82 

8.5 

84 

0.5 

98 

8.5 

84 

2.0 

91 

2.5 

89 

1.5 

95 

2.5 

89 

8.5 

84 

2.5 

89 

APPENDIX   III.— HYDROGRAPHIC   REPORT 


333 


TEMPERATURE  AND  RELATIVE  HUMIDITY  AT  CAMP  BARTON  ON  RIO  DESEADO,  1898.— Continued. 


Day. 


Max. 


1« 

7:t 

17..... 

75 

18 

74 

1« 

77 

20 

78 

21 

70 

22 

78 

23 

82 

24 

77 

25 

t   1 

26 

80 

27 

77 

28 

as 

29 

79 

30 

70 

31 

SO 

Min. 


71 
70 
71 
71 
72 

72 
71 
69 
70 
70 

72 
72 
68 
69 
70 
66 


January. 


Mean. 


I  M 

73 
78 
75 
75 

74 
75 
76 
74 
74 

75 
75 
75 
75 
75 
73 


Mean 
t-t'. 

0.0 
0.0 
0.0 
0.5 
0.5 

0.5 
0.5 
2.0 
1.0 
0.0 

0.5 
1.5 
2.5 
1.5 
2.0 
1.5 


Uelatlve 
humidity. 


100 

100 

100 

98 

98 

98 
98 
91 
95 
100 

98 
93 
89 
93 
91 
93 


Max. 


83 
76 

S3 
81 
84 

84 
81 
80 
80 
74 

78 
74 
77 


FEBRrARY. 

A 

^Iln. 

Mean. 

Mean 
t-t' 

Relative 
humidity. 

69 

76 

4.0 

82 

68 

73 

2.5 

88 

67 

76 

3.5 

a5 

72 

77 

8.5 

85 

71 

76 

S.5 

85 

71 

77 

4.5 

80 

81 

75 

2.5 

89 

69 

75 

2.0 

91 

71 

76 

2.5 

89 

70 

73 

1.5 

9b 

69 

74 

2.5 

88 

69 

71 

0.5 

98 

69 

73 

1.5 

95 

TEMPERATURE  AND  RELATIVE  HUMIDITY  AT  CAMP  BARTON  ON  RIO  DESEADO,  1898. 


March. 

April. 

Day. 

JL^ 

>. 

^ 

/ — 

~^*i 

% 

Max. 

Min. 

Mean. 

Mean 
t-t'. 

Relative 
humidity. 

Max. 

Min. 

Mean. 

Mean 
t-t'. 

Relative 
humidity. 

1 

76 

84 
84 
82 
78 

71 
70 
68 
7>3 
73 

74 

77     . 
74 
77 
76 

2.5 
4.0 
3.5 
2.5 
1.5 

88 
83 
84 
89 
98 

80 

84 
82 
82 
78 

72 
71 
72 
73 
74 

77 
78 
78 
78 
77 

2.0 
4.5 
8.5 
2.0 
0.5 

01 

2 

81 

3 

85 

4 

91 

98 

6 

80 

73 

77 

3.0 

87 

80 

76 

78 

1.5 

93 

7 

78 

72 

76 

1.5 

93 

83 

75 

79 

2.5 

89 

8 

83 

70 

76 

2.5 

89 

.84 

79 

82 

6.5 

74 

9 

74 

70 

72 

0.5 

98 

88 

71 

77 

8.5 

85 

10 

82 
83 

71 
72 

77 
78 

2.5 
4.5 

89 
81 

86 
80 

77 
79 

81 
80 

4.5 
3.0 

82 

11 

87 

12 

83 

74 

78 

4.0 

83 

85 

75 

80 

4.0 

83 

13 

87 

75 

80 

5.5 

77 

•    •   •    • 

■   •   •    » 

•   •   •   • 

*   *   *   * 

•    •   •   • 

14 

84 

71 

78 

4.5 

81 

•   •   •   • 

•   •   •   • 

•   ■   •   • 

•   •   •    • 

•    ■   •    • 

15 

85 

70 

78 

4.5 

81 

85 

68 

77 

5.0 

78 

16 

85 
84 

73 
75 

78 
79 

4.5 
4.5 

81 
81 

87 
87 

67 
75 

77 
81 

4.5 
4.5 

80 

17 

82 

18 

85 
86 

85 

86 

74 
69 
70 

72 

79 

78 
78 

78 

5.5 
5.5 
5.5 

4.5 

77 
77 
77 

81 

86 
80 
80 

80 

77 
76 

78 

76 

81 
80 

81 

81 

4.5 
8.5 
4.5 

4.5 

82 

19 

85 

20 

82 

21 

82 

22 

84 

73 

78 

3.5 

.     85 

77 

73 

75 

1.5 

98 

23 

S3 

72 

78 

3.5 

■     85 

SO 

74 

77 

1.0 

95 

24 

79 

72 

77 

2.0 

91 

84 

7:^ 

80 

4.0 

83 

25 

77 
83 

74 
75 

75 
79 

1.5 
4.0 

93 

83 

86 
75 

73 
74 

80 
75 

4.5 
1.0 

82 

26 

95 

27 

81 

72 

77 

2.0 

91 

82 

72 

78 

3.0 

87 

28 

84 
84 
82 

70 
73 
69 

*78 
78 
75 

4.5 
5.0 
3.5 

81 
79 

84 

84 
86 
83 

72 
73 
71 

79 
80 

78 

4.5 
5.0 
4.0 

81 

29 

79 

80 

83 

31 

84 

75 

79 

3.5 

85 

•    •    •    * 

•   ■   •   • 

•    ■   •    • 

•    ■   ■   • 

■    •   ■   ■ 

334 


NICARAGUA  CANAL  COMMISSION 


TEMPERATURE  AND  RELATIVE  HUMIDITY  AT  CAMP  BARTON  ON  RIO  DESEADO,  1898. 


Day. 

May. 

June. 

Max. 

Min. 

Mean. 

Moan 

t-t'. 

Kelative 
humidity. 

r — 

Max. 

Min. 

Mean. 

MeHn 
t-t. 

Relative 
humidity. 

1 

o 

80 

84 

74 
72 
72 
76 
75 

75 
79 
76 
76 
75 

75 
75 
75 
74 
77 

74 
74 
76 
75 
76 

74 
76 

78 
76 
77 

76 

78 
79 
76 
77 
75 

77 
78 
79 

78 
77 

79 

82 
82 
82 
78 

76 

80 
80 
81 
82 

78 
78 
78 
77 
78 

<  1 
80 
81 
79 
84 

83 
81 
84 
79 
81 
77 

1.0 
2.0 
3.5 
1.5 
0.5 

1.0 
3.5 
4.0 
4.5 
1.0 

0.5 
2.5 
3.5 
4.5 
4.5 

1.0 
1.0 
1.5 
1.5 
2.5 

1.0 
3.5 
3.5 
1.5 
5.5 

5.5 
3.5 
4.0 
2.0 
3.5 
0.5 

95 

91 
85 
93 
98 

96 
86 
84 
82 
96 

98 
90 

85 
82 
82 

96 
96 
93 
93 
89 

95 
85 
86 
94 

78 

78 
86 
84 
91 
86 
98 

78 
85 
86 
85 
85 

86 
83 

•  •  •  • 

•  •  ■  • 

85 

79 

81 

77 
78 
78 

80 
83 

84 
84 
80 

82 
82 
79 
78 
78 

81 
78 
81 
82 
80 

■  •  •  ■ 

76 
75 

81 
80 

82 

80 

77 

•  •  •  • 

•  •  •  • 

79 

75 
75 
76 
73 
75 

78 
77 
77 
75 

77 

76 
77 
76 
75 
75 

77  • 

75 

76 

73 

75 

•  •  •  • 

77 
80 
88 
82 
83 

83 
80 

•  •  •  • 

•  •  •  • 

82 

76 
79 
77 
75 

•    t  i 

79 

80 
81 
79 

78 

79 
80 
78 
76 
76 

79 
77 
77 

78 
78 

•  *  •  « 

0.5 
3.5 
5.5 
3.5 
4.5 

3.5 
2.5 

•  *  •  • 

•  •  •  • 

3.5 

0.5 
2.0 
0.5 
2.0 
0.5 

1.5 
1.5 
3.5 
8.0 
2.0 

2.0 
2.5 
•  1.0 
0.5 
1.0 

1.5 
1.5 
1.5 
2.5 
2.0 

•  •  •  * 

98 
85 

8 

4 

5 

6 

7 

85 
82 
80 

81 

H7 

78 
86 
82 

86 

89 

8 

87 

» 

10 

11 

86 
81 

78 

•  •  •  • 

86 
98 

12 

13 

84 
85 

91 
98 

14 

15 

16 

17 

18 

87 
88 

80 
81 
79 

91 
98 

94 
94 

86 

19 

20 

80 
79 

87 
91 

21 

22 

23 

80 

85 

87 

91 
89 
96 

24..-. 

25   .... 

82 
91 

98 
96 

26 

27 

28 

90 

85 
88 

94 
98 
98 

2!) 

82 

89 

30 

81 

84 
79 

91 

•  •  •  • 

TEMPERATURE  AND  RELATIVE  HUMIDITY  AT  CAMP  BARTON  ON  RIO  DESEADO.  1898. 


Day. 


JUIiY. 

AUOUBT. 

A_ 

■«— 

Max. 

Min. 

Mean. 

Mean 
t-t'. 

Relative 
humidity. 

Max. 

Min. 

Mean. 

Mean 
t-t'. 

Relative 
humidity 

80 

74 

78 

1.5 

93 

78 

75 

77 

1.0 

95 

76 

75 

76 

0.5 

98 

75 

73 

74 

0.5 

98 

•  •  • 

•  •  •  • 

•  •  •  • 

•  •  •  • 

■  •  •  • 

82 

74 

78 

1.0 

95 

•  •  • 

•  •  •  • 

•  •  •  • 

•  •  •  • 

•  •  •  • 

79 

74 

77 

1.0 

95 

•  •  • 

•  •  ■  • 

•  •  •  • 

•  •  •  • 

•  •  •  • 

81 

75 

79 

1.5 

94 

■  •  • 

•  •  ■  • 

•  •  •  • 

•  •  •  ■ 

•  ■  •  * 

82 

76 

79 

2.0 

91 

•  •  • 

•  •  •  • 

•  •  ■  • 

•  •  •  • 

*  •  «  • 

77 

75 

76 

0.5 

98 

80 

75 

77 

0.5 

98 

80 

76 

78 

1.0 

96 

•  •  • 

•  •  •  • 

.  •  •  • 

•  •  •  • 

•  •  •  • 

78 

76 

77 

0.5 

98 

82 

73 

77 

2.0 

91 

81 

74 

78 

1.5 

98 

84 

73 

79 

3.5 

85 

77 

76 

78 

1.0 

96 

83 

75 

80 

2.0 

92 

77 

75 

76 

0.5 

98 

85 

77 

81 

8.5 

86 

80 

75 

77 

1.5 

98 

84 

77 

80 

8.5 

85 

80 

75 

78 

1.0 

96 

85 

75 

80 

2.5 

89 

82 

76 

77 

:5.5 

89 

1, 

2. 
3. 
4. 
5. 

6. 
7. 
8, 
9. 
10. 

11. 
12. 
13. 
14. 
15. 


APPENDIX   III.— HYDROGRAPHIC   REPORT 


335 


TEMPERATURE  AND  RELATIVE  HUMIDITY  AT  CAMP  BARTON  ON  RIO  DESEADO.  1898.— Continued. 


Day. 


July. 


August. 


Max. 


MiD. 


Mean. 


Mean 
t-t' 


Relative 
humidity. 


Max. 


Min. 


Mean. 


Mean 
t-t.' 


Relative 
humidity. 


16 

17. 

18. 

19. 

20. 

21. 
22. 
28. 
24. 
25. 

26. 
27. 
28. 
29. 
80. 
81. 


84 
80 
80 
84 


79 

•  •  • 

79 
80 

79 

81 
88 
82 
80 
79 


78 
77 

4  I 

74 


78 


k  •  •  • 


78 
73 

74 
74 
75 
74 
77 
76 


81 
78 
78 
80 


76 

■  •  ■ 

76 
76 

76 

77 
78 
77 
79 
78 


3.5 
1.5 
1.5 
2.0 


1.0 

•  •  t 

1.5 
1.0 

0.5 
1.0 
1.0 
1.0 
2.5 
2.0 


86 
98 
98 
92 


95 

»  •  • 

98 
95 

98 
95 
96 
95 
89 
91 


80 
85 
80 
87 
80 

82 
84 
84 
82 
82 

80 
82 
80 
81 
82 
81 


78 
74 
78 
77 
74 

75 
74 
79 
79 

77 

77 
78 
79 
76 
75 
76 


79 
79 
77 

82 
79 

80 
80 
81 
81 
80 

78 
80 
79 
77 
79 
79 


2.5 
8.5 
2.5 
5.5 

2.0 

2.5 
8.0 
2.5 
8.0 
2.0 

1.5 
2.5 

2.0 
2.0 
2.5 


89 
85 
89 
78 
91 

89 
87 
90 
88 
9a 

98 
89 
89 
91 
91 
89 


TEMPERATURE  AND  RELATIVE  HUMIDITY  AT  CAMP  BARTON  ON  RIO  DESEADO,  1898. 


Day. 


Max. 


1 88 

2 82 

8 76 

5 

6 

I......  .... 

8 77 

9 81 

10 82 

11 88 

12 84 

18 84 

14 80 

15 82 

16 89 

17 87 

18 87 

19 79 

20 81 

21 85 

22 84 

23 87 

24 88 

25 83 

26 86 

27 86 

28 89 

29 91 

30 90 


September. 

A 


Min. 


Mean. 


Mean 
t-t'. 


Relative 
humidity. 


73 
77 
75 


75 
74 
75 

76 
75 
75 
74 
73 

73 
76 
78 
77 
75 

77 
74 
74 
76 
75 

75 
77 

78 
75 
80 


78 
80 
76 


76 

78 
79 

80 
80 
78 
79 
77 

81 
80 
82 
78 
79 

81 
79 
80 
81 
80 

81 
82 
83 
83 
85 


2.0 
3.0 
0.5 


0.5 
1.5 
2.0 

2.5 
8.0 
2.5 
2.5 
2.5 

2.0 
8.0 
8.5 
2.5 
2.0 

2.5 
8.5 
5.0 
5.5 
8.5 

5.0 
5.0 
5.5 
5.5 
5.5 


91 

87 
98 


98 
98 
91 

89 
87 
89 
89 
89 

92 

87 
86 
89 
91 

90 

85 
79 
78 
85 

80 
80 
78 
78 
78 


Max. 


87 
84 
81 
82 
81 

81 
85 
86 
86 

87 

86 
85 
80 
77 
79 

82 
89 
88 
89 
88 

87 
87 
82 
80 
74 

79 
88 

84 
89 

86 
87 


Min. 


75 
76 
75 
74 
75 

73 
74 
76 
76 
75 

73 

77 
77 
74 
74 

75 
75 
74 
76 

77 

76 
75 
75 
75 
73 

74 
74 
72 
73 
75 
75 


October. 

-A, 


Mean. 


82 
80 
78 
79 
79 

78 
80 
81 
79 
81 

81 
81 
78 
75 
76 

79 

82 
79 
83 
84 

82 
81 
79 
78 
74 

76 
79 
80 
83 
79 
80 


Mean 
t-t'. 


Relative 
humidity. 


5.0 

^0 

2.5 

89 

1.5 

93 

2.5 

89 

1.5 

94 

2.5 

89 

2.5 

89 

3.5 

86 

1.5 

94 

3.0 

88 

8.0 

88 

4.5 

82 

1.5 

98 

0.5 

98 

0.5 

98 

2.5 

89 

4.0 

84 

2.5 

89 

8.5 

86 

5.5 

78 

8.5 

86 

3.5 

86 

1.5 

94 

2.0 

91 

0.0 

100 

1.5 

98 

ao 

87 

4.0 

88 

5.5 

78 

2.0 

91 

3.0 

87 

336 


NICARAGUA  CANAL  COMMISSION 


TEMPERATURE  AND  RELATIVE  HUMIDITY  AT  CAMP  BARTON  ON  RIO  DESEADO.  1898. 


Day. 


November. 


r— — 
Max. 


December. 

» 


Mln. 


Mean. 


Mean 
t—V. 


Relative 
humidity. 


Max. 


Mln. 


Mean. 


Mean       Relative 
t— t'.      humidity. 


1 

2 

3, 

4. 

5. 

6, 
7. 
8. 
9. 
10, 

11, 

12, 

13 

14 

15 


10 
17 
18 
19 
20, 


«1 .... 

22 

23.... 
24.... 
25 


26. 

27. 
28. 
2» 
30 


88 
88 
84 
83 


79 
82 
75 
82 
76 

76 

74 
78 
78 
75 

83 
81 
80 
76 
77 

83 
80 
78 
80 
81 


75 
75 
75 
74 
73 


82.0 
81.5 
80.0 

78.5 


76 

•    •    •    • 

74 

75.5 

74 

76.0 

74 

78.5 

74 

74.5 

75 

78.5 

75 

75.5 

73 

74.5 

73 

73.5 

72 

74.5 

71 

74.5 

74 

74.5 

74 

78.5 

73 

77.5 

72 

77.0 

71 

74.0 

73 

75.0 

72 

76.5 

74 

77.5 

73 

76.0 

74 

77.0 

76 

78.5 

3.5 
5.5 
3.5 
2.5 


0.5 

0.5 
1.0 
0.0 
1.5 

'o.o 

0.0 
0.0 
0.5 
0.5 
0.5 

mt,tf 

1.5 
2.5 
0.5 
0.5 

1.5 
0.5 
0.5 
0.5 
2.0 


86 
78 
85 

89 

• 


98 

98 

90 

99 

»3.5 

99 

99 
99 
98 
98 
98 

89 
98 
89 

98 
98 

93 
98 
98 
98 
91 


76 
80 


•   •   •   • 


78 
80 
77 
79 
Y8 

75 

81 
79 
80 

81 

79 

82 
83 
82 
84 

79 

80 
79 


73 

74 

^   73 

•   •   •   • 

76 


74.5 

78.0 


76 

77.0 

73 

77.0 

73 

75.5 

72 

75.5 

74 

76.0 

72 

73.0 

71 

76.5 

78 

77.0 

69 

75.5 

70 

76.0 

72 

74.5 

72 

77.5 

72 

77.0 

70 

76.5 

71 

77.5 

72 

76.5 

70 

76.0 

70 

76.0 

66 

•    •   ■    • 

0.5 
1.0 


98 
96 


1.0 

95 

1.0 

95 

0.5 

98 

0.5 

98 

0.5 

98 

0.0 

100 

1.5 

93 

0.5 

98 

2.0 

91 

1.5 

93 

1.0 

95 

2.5 

89 

2.5 

89 

2.0 

91 

8.5 

85 

2.0 

91 

1.0 

95 

1.5 

93 

TEMPERATURE  AND  RELATIVE  HUMIDITY  AT  GREYTOWN,  NICARAGUA. 


Month. 


Tempkratithb. 


Max. 


Min. 


Mean. 


Mean 

relative 

humidity 


Month. 

1898. 
September. . . . 

October ^  . 

November  .... 
December  .... 
•  1899. 

January 

February  

March 


Temperature. 

Mean 

relative 

humidity 

r 

Max. 

Min. 

Meaiu 

96 

72 

81.2 

85.0 

96 

72 

81.4 

84.8 

92 

72 

79.7 

87.7 

91 

73 

78.8 

88.0 

86 

69 

77.8 

87.8 

88 

66 

77.2 

87.7 

90 

72 

79.7 

80.9 

1898. 

January 86 

February 84 

March 90 

April 89 

May SH 

June 90 

July 90 

Auirust 95 


67 
71 
69 
69 
78 
72 
74 
78 


77.5 
77.1 
78.4 
79.9 
80.4 
79.3 
80.0 
80.0 


82.5 
81.7 
80.2 
79.0 
82.1 
91.4 
91.3 
84.9 


APPENDIX   III.— HYDROGRAPHIC   REPORT 


337 


TEMPERATURE  AND  RELATIVE  HUMIDITY  AT  GREYTOWN,  NICARAGUA,  1898. 


Day. 

Jamtary. 

Max. 

Febrcahy. 

r 

Max. 

Mill. 

Mean. 

Mean 
t-t'. 

Relative 
humidity. 

Min. 

Mean. 

Mean 
t-t'. 

Relative 
humidity. 

1    

2 

3 

80 
74 
74 
74 
75 

79 

•  •   •    « 

•  •    •    • 

•  •    •   • 

82 

82 
83 
84 
82 
81 

70 

m^  mm 

1  1 

78 
84 
81 

83 
81 
83 
84 
83 

83 
82 
83 
86 
86 
83 

76 
73 
70 
67 
68 

75 

•  •   •   • 

•  •   •   • 

•  ■   •   • 

73 

73 
74 
74 
73 

71 

74 
73 
73 
74 
73 

74 
73 
75 
76 
75 

76 

1   i. 

71 
77 
74 
79 

78 
74 
72 
70 
72 

77 

•  V       •       • 

•  •    •    • 

•  •    •    • 

78 

78 
78 
79 

mmmt 

1  1 
76 

75 
76 
75 

80 
76 

79 

78 
80 
80 
80 

80 
79 

80 
82 
80 
82 

3.5 
4.5 
4.0 
3.0 
3.0 

3.5 

•  •   •   • 

•  ■   •    • 
■   •   •    • 

3.0 

2.5 
3.0 
2.5 
3.0 
3.0 

2.0 
2.5 
2.5 
4.5 
2.5 

4.0 
3.5 
5.5 
5.5 
5.5 

5.5 
0.0 
6.5 
7.5 
7.0 
7.0 

85 
80 
82 

80 

85 

•  •   •   * 

■    •   •    ■ 

•  •   •    • 

87 

89 
87 
89 
87 
87 

91 
89 
89 
81 
89 

83 
85 
77 

t    1 

77 

77 

74 
70 
72 
72 

79 
82 
84 
76 
79 

79 

84 
82 
83 
79 

83 

80 

HI 

79 
81 

84 

•  •    •    • 

•  •   •   ■ 

•  •   ■    • 

•  ■   •   • 

•  •   •   • 

■  •   •   • 

•  •   •   • 

•  •   •    • 

•  •    •    ■ 

■  •    •    * 

•  •   •    • 

■  •   •   • 

•  •   •    • 

•  •   •    • 

•  •   •    • 

75 
73 
74 
72 
72 

72 

/^•^ 

71 
72 
'71 

75 

t  t 

73 
77 
73 

71 

78 
77 
78 
74 
76 

76 
78 
76 
77 
76 

78 
78 
78 
78 
78 

77 

•  •    •    • 

•  •   •    • 

•  •   •    •                             < 

■  ■    •    • 

•  •   •    • 

■  •    •    • 

•  •    •    • 

■  •    •    • 

•  •    •    • 

■  •    •    • 

•  •    •    ■ 

•  •    ■    • 

•  ■       •       •                                                         4 

•  •       •       •                                                         * 
•       •      •       • 

4.5 
5.0 
5.5 
2.5 
4.5 

5.5 
5.5 
4.5 
4.5 
3.5 

2.5 
4.0 
2.5 
4.0 
4.5 

4.5 

t    •   •    • 
»    •    •    • 

•  •   • 

•  •    •    • 

1    •    •    • 

•  ■    •    • 

■  •    •    • 

•  •    •    • 

■  ■    •    • 

■  •    •    • 

•  •    • 
>    •    •    • 

•  •    • 

■  •    ■    • 

81 
78 
77 

4 

5 

0 

88 
80 

76 

7 

8 

9 

77 

80 
80 

10 

11 

12 

85 

89 
83 

13 

8() 

14 

15 

16 

17 

83 

81 

80 

18   

19 

20 

■    •    •   • 
•    ■    •   ■ 
1   •   •    • 

21 

22 

t 

■    •   ■   • 

23          . .      . . 

24 

25 

26 

27 

•  •   •   • 

•  •    •    • 

28 

29 

30 

31 

1 

«   •   •   ■ 

•  •   ■    • 

•  •   ■   • 

•  •   •   • 

TEMPERATURE  AND  RELATIVE  HUMIDITY  AT  GREYTOWN,  NICARAGUA,  1898. 


March. 

1 

April. 

Day. 

r 

Max. 

Min. 

Mean. 

Mean 
t-t. 

Relative 
humidity. 

Max. 

Min. 

Mean. 

Mean 
t-t'. 

Relative 
humidity. 

1 

75 

72 
74 
73 
74 

70 

77 
74 
74 
74 
72 

71 
71 
71 
69 
70 

73 

78 
78 
78 
76 

80 
79 
80 
76 
76 

80 
78 
80 
80 
79 

2.5 
4.0 
3.5 
3.5 
3.0 

3.5 
5.0 
6.0 
2.5 
4.0 

3.5 
3.5 
4.5 
6.5 
6.5 

88 
83 
85 
85 
87 

85 
79 
75 
89 
82 

85 
85 
81 
73 
73 

81 
87 
80 
84 

78 

80 
84 
83 
85 
84 

83 

85 
84 
83 
84 

72 

76 
75 
78 
74 

76 
79 
73 
74 
75 

74 
75 
76 
72 
69 

78 
82 
78 
80 
76 

78 
81 
78 
80 
80 

79 
81 
80 
78 
79 

4.5 
6.5 
3.5 
4.5 

1.0 

2.0 
4.5 
4.5 
5.0 
5.5 

4.5 
6.5 
5.5 
6.0 
6.5 

81 

2 

3 

4 

86 
82 
85 

78 
85 
81 

5 

83 

95 

6 

7 

8 

9 

10 

82 
82 
88 
78 
83 

91 
82 
81 
79 
77 

11 

85 

81 

12 

13 

14 

83 
90 

89 

78 
77 
75 

15 

87 
Z 

73 

2! 

338 


NICARAGUA  CANAL  COMMISSION 


TEMPERATURE  AND  RELATIVE  HUMIDITY  AT  GREYTOWN,  NICARAGUA,  1898.— Continued. 


March. 

April. 

Day.                     ' 

Max. 

Mln. 

Mean. 

Mean 
t-t'. 

UelaUve 
humidity. 

/ — 
Max. 

Min. 

Mean. 

Mean 
t-t'. 

Relative 
humidity. 

16 

81 

71 

77 

4.5 

80 

83 

70 

78 

6.5 

73 

17 

85 

70 

81 

5.5 

78 

83 

75 

80 

3.5 

85 

18 

81 

72 

78 

5.5 

77 

82 

77 

80 

4.5 

81 

19 

84 
85 

72 
75 

77 
80 

4.5 
7.5 

80 
81 

88 
86 

79 
73 

84 
82 

7.5 
6.0 

71 

20 

76 

21    .... 

84 

79 

81 

8.0 

68 

85 

74 

80 

5.5 

77 

22 

85 

71 

80 

5.0 

79 

84 

72 

78 

4.5 

81 

23 

83 

72 

78 

4.5 

81 

86 

74 

80 

3.5 

85 

24 

85 
85 

71 
75 

78 
78 

6.0 
3.5 

75 

85 

85 
89 

80 
80 

83 

84 

6.5 
8.0 

78 

25 

69 

26 

84 

79 

82 

6.5 

74 

84 

75 

80 

5.0 

79 

27 

86 

73 

80 

5.5 

77 

87 

75 

81 

7.0 

72 

28 

84 

72 

78 

6.0 

75 

83 

72 

80 

6.0 

75 

29 

83 
82 
83 

71 
69 
69 

76 
76 

81 

3.5 
.5.0 
5.5 

85 
78 
78 

83 
83 

•    •   •   • 

74 

71 

«   •   •   • 

80 

78 

•   •   *   • 

5.5 
5.5 

•   *  •   * 

77 

SO 

77 

31 

•   •   •   « 

TEMPERATURE  AND  RELATIVE  HUMIDITY  AT 

GREYTOWN,  NICARAGUA, 

1898. 

TV* 

May. 

June. 

USky, 

Max 

r 

• 

Min. 

Mean. 

Mean 
t-t'. 

— > 
Relative 
humidity. 

Max. 

Min. 

Moan. 

Mean 

t-t'. 

Relative 
humidity. 

1 

81 

73 
75 

78 
76 
76 

78 
78 
80 
80 
78 

3,5 
4.5 
6.5 
6.5 
5.5 

85 
81 
73 
73 

77 

82 
83 
84 
90 
90 

76 
75 
74 

77 
78 

78 
78 
78 
82 

82 

2.5 
2.5 
2.5 
2.0 
2.5 

89 

2 

80 

89 

3 

86 

89 

4 

85 

92 

5 

83 

90 

6 

84 

75 

78 

5.5 

77 

88 

77 

80 

2.0 

92 

7 

89 

79 

84 

6.0 

77 

88 

76 

80 

2.0 

92 

8 

94 

76 

83 

6.0 

76 

88 

75 

80 

2.5 

90 

9 

92 

77 

83 

5.5 

78 

86 

74 

79 

0.5 

98 

10 

84 

78 

80 

5.0 

79 

85 

74 

78 

1.5 

93 

11 

82 

75 

78 

1.5 

93 

90 

72 

80 

2.0 

92 

12 

88 

77 

80 

3.5 

85 

89 

72 

79 

2.0 

91 

13 

86 

78 

82 

5.5 

78 

84 

72 

78 

1.5 

93 

14 

86 

78 

82 

7.0 

72 

84 

74 

78 

1.5 

93 

15 

83 

77 
75 

80 
76 

5.5 
4.5 

77 
80 

86 

88 

77 
76 

80 
80 

2.0 
2.5 

92 

16 

78 

89 

17 

79 

75 
75 

78 
76 

3.5 
3.5 

85 
85 

86 
88 

77 

77 

80 

82 

2.5 
2.5 

89 

IS 

78 

90 

19 

82 

75 

78 

5.0 

79 

88 

75 

80 

2.5 

89 

20 

80 

80 

80 

1.0 

61 

88 

77 

80 

2.5 

89 

21 

85 

78 

81 

3.0 

87 

86 

76 

80 

2.5 

89 

22 

85 

74 
76 
76 

80 
80 
82 

2.5 
2.5 
2.5 

89.5 
89.5 
90 

85 
84 
80 

75 
74 
75 

78 
78 
78 

1.5 
0.5 
1.0 

93 

23 

S5 

98 

24 

90 

96 

25 

90 

79 

80 
79 

83 

83 
83 

2.0 

2.0 
2.0 

92 

92 
92 

86 

89 

84 

75 

74 
74 

78 

80 
78 

2.5 

2.5 
0.5 

89 

26 

89 

89 

27 

90 

98 

28 

90 

79 

80 

83 

82 

2.0 
5.5 

92 

78 

87 
87 

75 
74 

79 
79 

1.5 
1.5 

94 

29 

86 

94 

80 

86 

79 

78 

82 
81 

3.5 
3.5 

86 
86 

89 

•   •   *   • 

74 

•    •   •   • 

80 

*   •   •   • 

4.5 

•   «   •   ■ 

81 

31 

86 

APPENDIX  lU.— HYDROGRAPHIC   REPORT 


339 


TEMPERATURE  AND  RELATIVE  HUMIDITY  AT  GREYTOWN,  NICARAGUA,  1898. 


Day. 

July. 

A 

August. 

r — 

Max. 

Min. 

Mean. 

Mean 

t-t. 

Relative 
humidity. 

Max. 

Min. 

Mean. 

Mean 
t-t^ 

Relative 
humidity. 

I 

84 
80 
83 
79 

85 

88 
87 

74 
74 
75 
75 
74 

77 
76 
78 
75 
74 

75 
75 

•  •   •   • 

74 

•  •   •   • 

77 
76 

83 
78 

•  •   •   • 

78 
76 
78 
76 

78 

83 
81 
81 
79 
79 

80 
80 

•  •   •   • 

83 

•  •   •   • 

84 
SO 
84 
83 

•  ■   •    • 

3.5 
0.5 
1.5 
0.5 
0.5 

2.0 
1.5 
1.5 
1.5 
0.5 

1.5 
1.5 

•  •   •   • 

4.5 

•  •   ■   • 

4.5 
3.0 
4.0 
5.5 

•  •   ■   • 

•  •   •   • 

•  •   •   • 

•  •   •   • 

•  ■   •   ■ 

•  •   •   • 

•  •   •   • 

•  •   •   • 

•  •   •   • 

•  •   •   • 

•  •   ■   ■ 

•  ■   •   ■ 

89 
98 
93 
98 
98 

92 
94 
94 
94 
98 

94 
94 

•  •   •  • 

82 

•  •   •   • 

82 
87 
84 
82 

•  •   •   • 

•  •  •  • 

•  •  •  • 

•  •  •  • 

•  •  •  • 

•  •  •  • 

•  •  •  • 

•  •  •  • 

•  •  •  • 

•  •  •  • 

85 

•  •   •   • 

77 

•  •   •   • 

•  •  •   • 

•  •   •   • 

86 

•  •   •   • 
• 

•  •   •   • 

•  •   •   • 

•  •   •   • 

•  •  •   • 

87 
95 
86 

•  •   •    ■ 

82 
84 

•  •   •   • 

•  •   •   • 
■   •   •   ■ 

•  •   •   • 

77 

•  •  •   • 

75 

•  •   ■   • 

•  •   •   • 

•  ■   •   • 

73 

•  •   •   • 

•  •   •   • 

•  •   •   • 

•  •   •   • 

•  ■   •   • 

73 

78 
73 

•  •   •   • 

77 
74 

•  •   •   • 

•  •   •   • 

•  •   •   • 

•  •   •   • 

•  •   ■   • 

■  •   •   • 

•  •  •   • 

•  •  •   • 

•  •  •   • 

•  •  •   • 

•  •  •  • 

•  •  •   • 

•  •  ■   • 

81 

•  •   •   • 

76 

•  •   •   • 

•  •   •   • 

•  •  •   • 

80 

•  •   •   • 

•  •   •   • 

•  •   •   • 

■  •  •   • 

•  •   •   • 

80 

82 
81 

a    a    .    . 

80 
80 

•  •   •   • 

•  •   •   • 

•  •   •   • 

•  •   ■   • 

•  •  •  • 

•  •   ■   • 

•  •   •   • 

•  •  •  • 

•  •  •  • 

•  •  •   • 

•  •   •  • 

•  •  •   • 

•  •   ■  • 

4.5 

•  •  •   • 

1.5 

•  •  •  • 

•  •   •   • 

•  •   •   • 

3.0 

•  ■   •   • 

•  •   •   ■ 

•  •   •   • 

•  •  •   • 

•  •   ■    • 

3.5 
5.5 
4.5 

■   •  •   • 

8.5 
3.0 

•  •   •   • 

•  •   •   • 

•  •   •   • 

•  •   •    • 

3 

3 

4 

,5 

6 

7 

8 

88 
85 
85 

90 
90 

■   •           •   •   •   • 

89 

»   •           •   •   •   • 

90 

83 
80 
84 

>   ■           •   •   •   • 

•   •           •   •   •   • 

9 

10 

•   •  •   • 

82 

11 

13 

13 

14 

• .  •  • 
93 

•   •  •   • 

15 

16 

•   •   ■   • 

87 

17 

18 

19 

30 

31 

23 

■   •  •   • 

•  •   •   • 

•  •   •   • 

85 

23 

•  •           •   ■  •   ■ 

•  •           •   •   •   • 

■  •           •   •   •   • 

•  •           •   •   •   • 

■  •           •   •   •   • 

■  •           •    •   •   • 

•  •           •   •   »   » 

K       ■                       •       ■      ■       • 

78 

24 

35 

36 

37 

83 

•  •  •   • 

85 
87 

38 

39 

80 

.SI 

•  ft  •   • 

•  •   ■   • 

•  ■   ■    • 

TEMPERATURE  AND  RELATIVE  HUMIDITY  AT  GREYTOWN,  NICARAGUA,  1898. 


Day. 


September. 

October. 

r 

Max. 

Min. 

Mean. 

Mean 
t-t'. 

Relative 
humidity. 

Max. 

Min. 

Mean. 

Mean 

t-r. 

Relative 
humidity. 

•   •   •   • 

•    •   •    • 

■   •   •   • 

•   •   •   • 

•   •   •   • 

90 

76 

S8 

4.5 

82 

84 

73 

80 

3.5 

85 

93 

74 

83 

4.5 

82 

80 

75 

77 

2.0 

91 

83 

72 

75 

2.5 

89 

•    •   ■   ■ 

■   •   •   • 

•   •   •    • 

•   •   •   • 

•   •   •   • 

86 

73 

79 

3.5 

85 

83 

78 

80 

3.5 

85 

• 

83 

74 

80 

3.0 

87 

84 

•   •   •    • 

•    ■   •    • 

•   •   •   • 

■   •   ■  • 

83 

74 

79 

2.5 

*      89 

83 

75 

79 

2.5 

89 

90 

7(i 

K3 

3.5 

86 

79 

74 

76 

1.5 

93 

84 

80 

2.5 

89 

•  84 

78 

.      79 

3.0 

87 

93 

74 

88 

5.0 

80 

83 

73 

79 

8.5 

85 

94 

73 

88 

6.5 

74 

•    ■   •   • 

•   ■   • 

•    ■   •   • 

•   •   •   • 

•  •   •   • 

91 

74 

81 

4.5 

82 

•    •   •    • 

•   •  •  • 

•   •   •   • 

•   •  •  • 

•   •   • 

90 

73 

81 

4a  0 

84 

•   •   •   • 

•   •    • 

•    •   ■   • 

•   •   •   • 

•   •   •   • 

82 

72 

78 

3.0 

87 

•   ■   •   • 

•   •   •   • 

•   •   •   • 

•   •   •    • 

•   •   •   • 

80 

74 

76 

2.0 

91 

91 

80 

84 

4.5 

82 

80 

74 

i   1 

2.0 

91 

1. 

o 

*0  m 
8a 
4. 

5. 

6. 
7. 

8. 

9a 

10 

11. 

13. 

13  a 

14  a 
15. 


340 


NICARAGUA  CANAL  COMMISSION 


TEMPERATURE  AND  RELATIVE  HUMIDITY  AT  GREYTOWN,  NICARAGUA,  1898.— Continued. 


Day. 

8KPTEMBRK. 

OCTOBKK. 

'' 

\ 

' 

-» 

Max. 

Min. 

Mean. 

Mean 

t-f. 

Relative 
humidity. 

Max. 

Min. 

Mean. 

Mean 
t-f. 

Helative 
humidity. 

16 

•                        •    •   •    • 

•    ■    ■    • 

•    •   •   • 

•    •   •    • 

•    ■    •   • 

85 

74 

80 

8.0 

87 

17 

■                        •    ■   •   • 

•    •   •    • 

•    •   •   • 

•   •   ■   • 

•    •  •   • 

86 

75 

81 

3.5 

86 

18 

•                        •    ■   ■    • 

•    •    •    • 

■    •   •   • 

•   •    •   • 

•    •   •   • 

89 

74 

81 

2.5 

90 

19.; 

79 

76 

78 

1.5 

93 

90 

74 

S2 

4.5 

82 

wU 

81 

74 

78 

1.5 

93 

91 

76 

83 

5.0 

80 

21 

88 

74 

81 

3.5 

86 

91 

76 

83 

4.0 

84 

22 

89 

74 

81 

2.5 

90 

96 

76 

85 

4.5 

82 

28 

93 

72 

82 

5.0 

80 

84 

80 

82 

3.5 

86 

24 

92 

73 

85 

7.0 

73 

85 

74 

80 

3.5 

85 

25 

89 

85 
84 

7(J 

76 
75 

82 

80 
80 

2.5 

2.5 
3.5 

90 

89 
85 

90 

85 
90 

73 

74 
73 

82 

80 
82 

3.5 

4.5 
3  5 

86 

26 

81 

27 

86 

28 

91 

80 

86 

5.5 

79 

90 

83 

86 

3.5 

86 

29 

9(i 

83 

88 

7.5 

72 

92    . 

84 

88 

4.5 

83 

30 

95 

84 

•   •   •   • 

88 

■   •   •    • 

7.5 

•    •   •   • 

72 

■    •    •   ■ 

85 
95 

76 
74 

81 
86 

2.5 
6.0 

90 

31 

1 1 

TEMPERATURE  AND  RELATIVE  HUMIDITY  AT  GREYTOWN,  NICARAGUA,  1898. 


Day. 

NOVEMBKK. 

• 

Dkcembek. 

r 

^~S 

f* 

"~^ 

Max. 

Min. 

Mean. 

Mean 
t-f. 

Relative 
humidity. 

Max. 

Min. 

Mean. 

Mean 

t-f. 

Relative 
humidity. 

1 

92 

7(» 

83.5 

4.5 

82 

80 

72 

76.5 

2.0 

91 

2 

89 

74 

83.0 

4.5 

82 

8(> 

75 

81.0 

2.5 

90 

3 

84 

79 

81.0 

5.5 

78 

85 

77 

80.5 

2.0 

92 

4 

91 

74 

82.5 

7.0 

72.5 

91 

77 

84.0 

4.5 

82 

5 

87 

7(J 

81.0 

3.5 

86 

79 

77 

78.0 

2.5 

89 

6 

77 

74 

76.0 

2.0 

91 

82 

76 

79.5 

1.5 

94 

7 

78 

74 

76.5 

2.0 

^        91 

85 

73 

79.5 

3.5 

85 

8 

78 

73 

76.0 

3.5 

85 

85 

75 

78  5 

2.5 

89 

9 

89 

76 

84.0 

4.5 

82 

82 

72 

76.0 

3.5 

85 

10 

83 

73 

77.5 

3.5 

85 

83 

75 

78.0 

2.5 

89 

11 

86 

76 

80.5 

4.5 

81.5 

76 

73 

74.5 

1.5 

93 

12 

88 

74 

82.5 

3.0 

88 

84 

72 

77.5 

2.5 

89 

13 

78 

74 

76.0 

1.5 

93 

85 

74 

77.5 

2.5 

89 

14 

87 

76 

83.0 

90 

85 

74 

3.0 

87 

15 

78 

76 

77.0 

1.5 

93 

85 

72 

76.5 

3.0 

87 

16 

78 

75 

76.5 

1.5 

93 

83 

74 

77.5 

2.5 

89 

17 

78 

72 

75.5 

0.5 

98 

83 

74 

77.0 

2.5 

89 

18 

78- 

75 

76.5 

1.5 

93 

85 

74 

78.0 

4.0 

83 

19 

86 

7(J 

81.5 

2.5 

90 

85 

74 

77.5 

3.5 

85 

20 

82 

75 

77.5 

3.0 

87 

85 

74 

78.5 

3.5 

85 

21 

84 

72 

79.5 

3.5 

85 

87 

76 

80.5 

3.5 

85.5 

22 

85 

76 

81.0 

3.5 

86 

87 

74 

80.5 

5.5 

77.5 

23 

83 

76 

79.5 

2.5 

89 

84 

75 

79.0 

2.5 

89 

24 

84 

76 

81.0 

0.5 

98 

86 

70 

78.0 

1.0 

96 

25 

82 

74 

78.5 

2.0 

91 

85 

73 

79.0 

5.5 

77 

26 

86 

76 

79.5 

3.5 

85 

•   •   •   • 

74 

•   •   •   • 

•    •   •   • 

•    •   ■   • 

27 

85 

76 

80.5 

2.0 

92 

•   •   ■    ■ 

•   •   ■    • 

•    •   •    • 

•   •   t   • 

•   •   •    • 

28 

87 

76 

82.5 

3.5 

80 

■   ■    •    • 

•    «   •    • 

•    •   •   • 

•    •   •   • 

•   •   •   • 

29 

85 

76 

81.0 

8.5 

86 

80.0 

77 

78.5 

2.0 

91 

30 

86 

76 

80.0 

2.0 

92 

80.0 

72 

76.0 

1.5 

93 

81 

•    «    •    • 

•   ■    •    • 

•    ■   •   • 

•   ■   •   • 

•   •  • 

82.0 

74 

77.5 

2.0 

91 

APPENDIX   III.— HYDROGRAPHIC   REPORT 


341 


TEMPERATURE  AND  RELATIVE  HUMIDITY  AT  GREYTOWN,  NICARAGUA,  1899. 


Januaby. 

1 

Februaky. 

Day. 

r 

Max. 

Min. 

Mean. 

Mean 

Relative 
humidity 

• 

Max. 

Min. 

Mean. 

Mean 
t-t'. 

Relative 
humidity. 

1 

79 

77 

75.0 

3.5 

84 

83 

79 

79.5 

4.5 

81 

2 

86 

78 

81.0 

4.5 

83 

84 

72 

78.0 

3.5 

85 

3 

83 

76 

79.0 

3.0 

87 

83 

73 

78.0 

3.5 

85 

4 

84 

74 

79.0 

2.5 

89 

81 

73 

76.0 

3.5 

89 

5 

83 
82 

74 
73 

77.5 
77.5 

2.0 
2.0 

- 

91 
91 

83 
84 

73 
73 

77.0 
76.5 

3.0 
1.5 

87 

6 

93 

7 

83 

73 

76.5 

2.5 

89 

87 

73 

77.5 

3.0 

87 

8 

85 

71 

77.5 

2.5 

89 

88 

73 

78.5 

2.5 

89 

9 

84 

73 

78.5 

3.5 

85 

84 

74 

77.5 

3.0 

87 

10 

.     .     83 

72 

77.5 

2.0 

91 

81 

73 

75.5 

3.0 

87 

11 

85 

73 

78.5 

2.5 

89 

86 

74 

80.0 

3.0 

87 

13 

82 

74 

78.5 

3.0 

87 

84 

73 

79.5 

1.5 

94 

IS 

82 

75 

78.5 

3.5 

85 

76 

74 

75.0 

3.5 

84 

14 

83 

73 

77.0 

2.0 

91 

71 

66 

69.0 

1.5 

93 

1.5 

83 
80 

75 
74 

79.0 
77.5 

4.0 
2.0 

83 
91 

77 

82 

70 
70 

73.5 
76.0 

1.5 
2.0 

93 

16 

91 

17 

81 

73 

76.5 

2.5 

89 

86 

73 

80.5 

3.5 

85 

18 

81 

73 

77.5 

2.5 

89 

84 

73 

78.0 

3;o 

87 

19..:.... 

79 

76 

77.5 

3.5 

85 

84 

74 

78.0 

3.0 

87 

20 

82 

73 

77.5 

2.5 

89 

85 

73 

78.5 

3.5 

85 

31 

85 

73 

78.5 

3.0 

87 

82 

75 

79.0 

2.5 

89 

22 

84 

71 

77.5 

3.5 

85 

84 

77 

80.0 

2.5 

89 

23 

82 

72 

77.5 

3.5 

85 

84 

79 

81.0 

4.5 

82 

24 

80 

74 

77.5 

2.5 

89 

81 

74 

77.0 

2.0 

91 

25 

83 

73 

77.5 

3.5 

85 

82 

76 

78.5 

3.5 

85 

26 

81 

72 

77.5 

3.0 

87 

•   •   •   • 

•  • . . 

■   •   •   • 

•   •   •   • 

•   •   •   • 

27 

83 

71 

77.0 

3.5 

85 

83 

74 

78.5 

2.0 

91 

28 

84 

69 

76.5 

3.5 

85 

84 

77 

79.5 

3.5 

85 

29 

•           •    •   •   • 

•   ■   • 

•    •   •    • 

•   •   •    • 

• 

•  •   • 

•    •   •   • 

•   •   ■   • 

•    •   •    • 

•   •   •   • 

•    •   •    • 

30 

84 

71 

77.5 

3.5 

85 

•   ■   •   • 

•   •   •    • 

•   ■   •   • 

•   •   •   ■ 

■    •   •    • 

31 

85 

72 

78.5 

2.5 

89 

■    •   •    • 

•   •    •    • 

•   ■   •   ■ 

•   •   •   • 

•   •   • 

TEMPERATURE  AND  RELATIVE  HUMIDITY  AT 

6REYT0WN, 

NICARAGUA, 

1899. 

March. 

Day. 

Max. 

Min. 

Moan. 

Mean 
t-t'.      ] 

Relative 
tiumidity. 

Day. 

Max. 

1 

Min. 

Mean. 

Mean 

t— t'. 

Relative 
humidity. 

1 

81 

75 

77.5 

3.0 

87 

17 

80 

73 

76.5 

2.5 

89 

2 

83 

75 

79.0 

3.5 

85 

18 

86 

73 

78.0 

4.0 

83 

3 

82 

74 

77.5 

3.0 

87 

19 

86 

75 

80.0 

4.0 

83 

4 

84 

74 

78.5 

4.0 

83 

20 

89 

77 

81.5 

5.0 

79 

5 

84 

73 

79.0 

4.5 

81 

21 

87 

77 

81.0 

5.5 

78 

0 

89 

78 

80.5 

5.0 

80 

22 

90 

75 

81.0 

4.5 

82 

7 

78 

73 

76.0 

8.5 

85 

23 

86 

77 

80.5 

6.0 

76 

8 

84 

77 

79.5 

6.0 

75 

34 

86 

75 

79.5 

4.5 

81 

9 

84 

76 

79.0 

4.5 

81 

25 

89 

76 

81.5 

6.5 

74 

10...... 

86 

78 

81.5 

7.5 

70 

26 

86 

76 

80.5 

5.0 

79 

11 

87 

73 

79.0 

5.5 

77 

27   .... 

88 

75 

81.0 

5.5 

78 

12 

85 

74 

79.0 

2.5 

89 

28 

83 

75 

79.0 

3.5 

85 

18 

86 

75 

79.5 

4.5 

81 

29 

86 

76 

80.5 

8.5 

86 

14 

82 

75 

78.5 

3.0 

87 

oU 

88 

78 

83.0 

6.5 

74 

15 

86 

76 

80.5 

5.0 

80 

81 

87 

78 

81.5 

6.0 

76 

16 

88 

76 

81.5 

6.0 

76 

APPENDIX  IV 


REPORT 


ON  THE 


WESTERN  DIVISION 


BY 


J.  W.  G.  WALKER 

Assistant  Engineer 


CONTENTS 

PAGE 

Itinerary    347 

Canal  Belt 349 

Rio  Las  Lajas 350 

Rio  Grande 351 

Method  of  Conducting  Survey 351 

Obstacles  to  Survey 351 

Personnel   352 

Distance  Run   352 

Result  of  Survey 352 

Alternate  Routes. 

Ilydrographic  Considerations 352 

Rio  Medio  Route 353 

Canal  Company's  Low-Level  Route 353 

Canal  Company's  High-Level  Route 354 

Nicaragua  Canal  Commission's  Location 355 

General. 

Labor 355 

Health 355 

Food  Supply 355 

Water  Supply 356 

Fuel 356 

Land   356 

Hubs 356 

Roads    356 

Police  System — 356 

Postal  Svstem 356 

Monopolies   356 

Earthquakes   357 

Conclusion   357 


APPENDIX  IV 


Washington,  D.  C,  April  20,  1899. 

Mb.  E.  S.  Wheeleb, 

Chief  Engineer,  Nicaragua  Canal  Commis- 
sion, Washington,  D.  C. 

Sir: — ^In  compliance  with  the  instructions 
contained  in  your  letter  of  February  21  I  have 
the  honor  to  submit  the  following  report  of  my 
entire  operations  connected  with  the  Nicaragua 
Canal  Commission,  including  all  matters  which 
seem  to  me  of  interest  or  of  value  to  the  Com- 
mission. 

I  was  appointed  an  Assistant  Engineer  by  the 
Commission  on  the  6th  day  of  August,  1897, 
and  entered  at  once  upon  the  discharge  of  my 
duties.  These  duties  were  varied  in  character 
and  included  the  compilation  of  information 
likely  to  prove  useful  in  our  subsequent  investi- 
gations, as  well  as  the  ordering  and  inspection 
of  various  articles  of  equipment  necessary  for 
the  proper  prosecution  of  work  in  the  field. 

On  the  5th  of  December  I  sailed  from  New 
York  for  Greytown  on  the  gunboat  "  Newport," 
with  the  members  of  the  Commission  and  the 
engineering  staff.  Landing  at  Greytown  on  the 
18th  instant  I  immediately  proceeded  to  the 
Nicaragua  Canal  Construction  Company's  build- 
ings at  La  Fe,  where  a  temporary  camp  was  es- 
tablished under  the  direction  of  Lieutenant 
Eanus,  TJ.  S.  Navy. 

On  the  2l8t  of  December  I  received  instruc- 
tions to  take  charge  of  Topographical  Party 


No.  1,  and  to  make  all  necessary  surveys  be- 
tween Lake  Nicaragua  and  the  Pacific  ocean. 
Nine  assistants  from  the  engineering  staff  were 
assigned  to  me  and  I  was  directed  to  equip  my 
party  and  proceed  as  soon  as  possible  to  my 
destination.  By  working  on  Christmas  day  and 
Sunday,  I  was  able  to  take  the  steamer  "  Hollen- 
beck"  from  Greytown  on  Monday  morning, 
December  27,  and  at  about  3  o'clock  Tuesday 
afternoon  we  reached  Castillo  and  passed  the 
custom  house,  but  remained  aboard  the  "  Hol- 
lenbeck  "  for  the  night. 

Wednesday  morning  was  spent  in  transferring 
our  freight  and  ourselves  to  the  steamer  "  Vero," 
which  lay  above  the  rapids,  and  at  one  o'clock 
we  left  for  San  Carlos,  reaching  there  about 
nine  o'clock  in  the  evening.  Here  we  transfer- 
red to  the  lake  steamer  "  Victoria,"  which  was 
lying  at  the  dock  awaiting  the  arrival  of  another 
river  boat  before  sailing  for  San  Jorge.  The 
next  day  was  spent  at  San  Carlos,  but  late  in 
the  afternoon  of  the  31st,  we  sailed  for  San 
Jorge,  the  port  of  Rivas. 

Reaching  San  Jorge  early  New  Year's  morn- 
ing, I  proceeded  at  once  to  Rivas  and  arranged 
to  quarter  my  party  at  the  house  of  Mrs.  Run- 
nels, while  I  was  hiring  laborers,  breaking  out 
freight,  and  arraBging  to  put  my  party  into  the 
field.  As  it  was  a  "feast  day"  it  was  almost 
impossible  to  accomplish  anything,  but  I  finally 
succeeded  in  hiring  four  carretas,  or  native  ox 


348 


NICARAGUA   CANAL  COMMISSION 


carts,  and  hauling  our  freight  to  Rivas.  1  also 
engaged  Nicanor  Ortega,  an  intelligent  native, 
who  has  been  on  manv  survevs,  and  directed 
him  to  employ  twenty  laborers,  telling  him  that 
I  should  hold  liim  responsible  for  their  efficiency 
and  good  behavior. 

The  next  day  being  Sunday  my  party  re- 
mained in  Rivas,  but  in  the  aftenioon  I  rode 
out  to  the  mouth  of  the  Rio  Las  Lajas  with  Mr. 
F.  II.  Davis,  an  American  resident,  to  obtain 
an  idea  of  the  character  of  the  country  in  which 
the  first  part  of  our  work  would  lie. 

Monday  morning,  the  3rd  of  January,  we 
loaded  most  of  our  possessions  upon  carretas  and 
moved  out  to  San  Pablo,  on  the  bank  of  the  Rio 
Las  Lajas  about  one  and  a  sixth  miles  from 
Lake  Nicaragua.  The  remainder  of  the  day 
was  spent  in  erecting  our  tents  and  getting  the 
camp  into  shape. 

From  this  time  on  the  work  was  i)rosecuted 
with  great  vigor.  It  had  been  my  intention  to 
re-run  the  line  adopted  by  the  Canal  Company 
as  their  final  location,  putting  in  the  adjacent 
topography  with  comparatively  little  instrumen- 
tal work,  but  I  soon  became  convinced  that 
owing  to  the  character  of  the  country  and  the 
denseness  of  the  vegetation,  topography  so  ob- 
tained would  be  very  unreliable  while  the  strip 
of  country  covered  w^ould  be  too  narrow  to  em- 
brace all  locations  which  the  Commission  might 
desire  to  study.  I  therefore  sought  and  ob- 
tained your  permission  to  change  my  plan  of 
action  and  to  make  a  detailed  survey  from  Lake 
Nicaragua  to  the  Pacific  ocean  of  a  belt  of  coun- 
trj'  containing  all  practicable  locations.  In  order 
to  perform  this  work  rapidly  and  economically 
I  increased  the  size  of  my  party,  taking  Mr.  F. 
H.  Davis  as  an  additional  transitman  and  Messrs. 
Fred.  Davis  and  A.  L.  Scott  as  assistants.  This 
enabled  me  to  nm  four  instruments — two  tran- 


sits and  two  levels — and  to  accomplish  twice  as 
much  work  per  month  w^ithout  a  correspond- 
ing increase  in  expenses.  I  decided  to  run  a 
main  line  following  as  nearly  as  practicable  the 
Canal  Company's  low-level  location,  cross  sec- 
tioning or  running  such  side  lines  as  would  best 
give  us  the  desired  topographical  information. 
These  topographical  lines  were  in  general  so 
arranged  as  to  form  a  series  of  traverses  with  the 
main  line,  thus  enabling  us  to  immediately  de- 
tect any  considerable  inaccuracy  and  to  correct 
it  before  proceeding  with  our  work. 

By  the  6th  of  February  our  main  line  had 
reached  the  telegraph  road  from  Rivas  to  San 
Juan  del  Sur,  about  three  and  two-thirds  miles 
from  the  lake,  and  we  moved  camp  to  Espinal, 
on  the  summit  of  the  Continental  Divide. 

During  this  period  of  our  work  we  were  much 
annoyed  and  delayed  by  the  frequent  impress- 
ment of  our  laborers  for  military  service.  Nica- 
ragua was  suffering  from  one  of  the  civil  wars 
so  frequent  in  her  history  and  although  we  were 
freely  furnished  with  boletus,  or  safe  conducts, 
for  our  men,  there  were  few  instances  in  which 
they  were  respected  by  sub-officials  of  the  gov- 
ernment which  issued  them.  Laborers  in  camp 
or  actually  at  work  in  the  field  were  never  mo- 
lested, but  messengers  or  stragglers  were  often 
seized  and  imprisoned  despite  the  boletas  which 
they  carried.  A  personal  appeal  to  the  authori- 
ties always  resulted  in  the  release  of  such  em- 
ployees, but  the  time  and  energy  expended  in 
protecting  our  men  might  have  been  utilized 
elsewhere  to  advantage.  My  American  assist- 
ants were  never  interfered  with  and  although  I 
was  twice  seized  by  bands  of  armed  insurgents, 
I  was  courteously  treated  and  released  upon  es- 
tablishing my  identity. 

My  chief  difficulty  was  in  obtaining  supplies, 
since  the  government  had  seized  the  "  Victoria  '* 


APPENDIX   IV.— REPORT   OF  J.   W.   G.   WALKER,   ASSISTANT   ENGINEER 


349 


and  commiiuication  with  the  east  coast  was  in- 
terrupted. In  this  (connection  I  wish  to  express 
my  indebtedness  to  Dr.  S.  M.  Cole,  an  Ameri- 
can resident  of  Kivas,  whose  kindness  in  advanc- 
ing funds  enabled  me  to  tide  over  a  critical 
period  in  my  party's  aflFairs. 

On  February  26,  our  survey  having  reached 
a  point  about  six  and  four-tenths  miles  from  the 
lake,  WT  moved  camp  to  a  place  called  Paraiso, 
in  the  tipper  part  of  the  gorge  of  the  Rio 
Grande.  Here  the  country  is  very  rough,  quite 
diflFerent  from  the  gently  rolling  territory  which 
our  center  line  had  passed  through  heretofore, 
but  as  only  one  location  for  the  canal  is  practi- 
cable, we  were  spared  the  necessity  of  extending 
our  survey  as  far  laterally  as  we  had  previously 
done. 

On  March  23rd  we  moved  our  camp  from 
Paraiso  to  El  Pavon,  at  the  (entrance  to  the  Tola 
basin,  and  l)v  the  end  of  the  month  our  surv^ev 
had  reached  a  point  about  eight  and  four-tenths 
miles  from  the  lake.  During  the  last  half  mile 
of  this  distance  a  great  deal  of  work  was  done 
south  of  the  main  line  in  order  to  include  a  pos- 
sible railway  location  above  the  110-foot  con- 
tour. 

On  the  23rd  of  April  we  moved  camp  to  a 
spot  south  of  the  Rio  Grande  just  below  the  site 
of  the  proposed  La  Flor  dam,  and  by  the  end  of 
the  month  our  work  was  completed  to  a  point  ten 
and  six-tenths  miles  from  the  lake.  With  the  ex- 
ception of  the  meander  of  the  110-foot  contour 
on  the  north  side  of  the  Tola  basin,  the  belt  of 
country  available  for  canal  construction  had 
been  surveyed  and  platted  and  an  examination 
made  for  a  railway  location  above  the  110-foot 
contour  on  the  south  side  of  the  Tola  basin. 

On  the  Ist  of  ilay,  as  the  rainy  season  was 
approaching,  and  our  tents  afforded  shelter  in- 
sufficient for  the  whole  party,  I  was  constraineil 


to  reduce  mv  force  materiallv  and  to  finish  the 

«  •/' 

survev  with  onlv  two  instruments. 

Our  last  work  in  connection  with  the  main 
line  at  Brito  was  finished  on  the  27th  of  June, 
but  a  sudden  rise  in  the  Rio  Grande  prevented 
us  from  crossing  it  until  the  30th,  when  we 
moved  camp  to  a  point  on  the  Rio  Tola  about 
one  and  a  fifth  miles  from^  the  town  of  Tola. 
The  entire  meander  of  the  110-foot  contour  on 
the  north  side  of  the  Tola  basin  and  of  the  Rio 
Tola  and  tributarv  streams  was  done  from  this 
camp,  which  was  centrally  located.  This  work 
was  finished  on  the  0th  of  August. 

On  the  10th  of  August  we  moved  our  camp 
to  a  place  on  the  Rio  Grande  five  hundred  feet 
above  the  point  where  our  main  line  first  crossed 
it  and  near  the  hacienda  called  El  Carmen. 
From  this  camp  we  meandered  the  upper  Rio 
Grande,  Cascabel  creek,  and  Cauas  Gordas 
creek,  and  ran  various  lines  for  topography. 
We  also  ran  a  line  up  Guarumo  creek  and  down 
Comalcaqua  creek  to  its  junction  vnth  the  Rio 
Juan  Davila,  putting  in  enough  of  the  adjacent 
topography  to  enable  us  to  locate  and  compute 
a  channel  to  divert  the  upper  Rio  Grande  east- 
ward into  Lake  Nicaragua  should  it  be  thought 
advisable.  This  work  was  finished  the  20th  of 
September,  and  on  the  22nd  we  moved  to  Rivas, 
stored  our  camp  equipment  and  disbanded  the 
party. 

I  returned  to  the  United  States  by  way  of 
Panama,  accompanied  by  Messrs.  E.  B.  Harden, 
and  M.  A.  Coroalles,  the  other  members  of  the 
party  having  assumed  the  duties  to  which  you 
had  previously  assigned  them. 

Canal  Belt. 

What  may  be  termed  the  canal  belt  between 
Lake  Nicaragua  and  the  Pacific  ocean  begins  on 
the  lake  at  the  mouth  of  the  Rio  Las  Lajas.     A 


350 


NICARAGUA  CANAL  COMMISSION 


tangent  from  the  initial  point  with  a  magnetic 
bearing  of  about  south  sixty-one  degrees  west 
forms  the  longitudinal  axis  of  this  zone,  traverses 
a  gently  rolling,  partially  wooded  valley,  crosses 
the  river  four  times,  and  leaving  it  six  thousand 
eight  hundred  feet  from  the  lake,  follows  the 
valley  of  Guiscoyol  creek  to  a  point  12,900  feet 
beyond.  Here  the  axis  of  the  zone  curves 
gently  to  the  right,  crosses  the  summit  of  the 
Continental  Divide  at  an  elevation  of  164  feet 
above  the  sea  and  a  distance  of  five  miles  from 
Lake  Nicaragua  and  dropping  gently  down,  en- 
ters the  valley  of  the  Rio  Grande.  Following 
the  river  in  a  northwesterly  direction  and  cross- 
ing and  recrossing  it  repeatedly,  it  runs  for 
nearly  two  miles  through  a  rough  country  be- 
tween precipitous  hills  where  outcrops  of  par- 
tially disintegrated  rock  are  eveiywhere  visible. 
Emerging  from  this  rocky  gorge  with  a  westerly 
bearing,  it  almost  immediately  curves  to  the 
northward  through  the  plain  at  the  mouth  of 
Guachipilin  creek,  and,  still  following  the  gen- 
eral direction  of  the  Kio  Grande  with  a  bearing 
of  about  north  fifty-four  degrees  west,  runs 
through  a  gravelly  and  somewhat  rock  valley 
between  high  hills  1000  to  1500  feet  apart  to  the 
Tola  basin,  which  it  enters  at  a  distance  of  about 
ten  and  a  half  miles  from  the  lake. 

The  Tola  basin  is  a  broad,  alluvial  plain,  very 
level  and  heavilv  timbered,  and  but  for  the 
problem  of  handling  the  flood  waters  of  the  Rio 
Grande  and  Rio  Tola,  the  location  of  a  canal 
would  be  a  very  simple  problem,  two  points  be- 
ing determined  by  its  entrance  into  the  basin  and 
by  the  gap  in  the  La  Flor  hills  through  which 
it  must  make  its  exit  in  a  southwesterly  direc- 
tion. Beyond  these  hills  is  a  broad,  alluvial 
plain  bounded  by  widely  separated  ranges  of 
hills  and  gradually  sloping  down  to  the  beach  at 
Brito,  three  miles  away. 


Nearly  the  entire  canal  belt  is  heavily  tim- 
bered, the  only  considerable  open  tract  being  in 
the  big  bend  of  the  Rio  Grande  below  La  Flor. 

The  harbor  possibilities  at  Brito  are  limited  by 
the  precipitous  rocky  headland  known  as  Brito 
Head  and  by  a  rocky  hill  some  7000  feet  to  the 
southeastward.  These  two  eminences  are  the 
termini  of  the  ranges  of  hills  bounding  the  val- 
ley, which  in  its  lower  portion  is  a  silted  estuary 
extensively  inundated  at  high  tide  and  over- 
grown with  a  tangled  mangrove  forest. 

The  beach,  which  extends  from  the  southeast- 
ern hill  to  the  mouth  of  the  Rio  Grande,  is  of 
white  sand  quite  different  from  the  material 
brought  down  by  the  river,  and  this,  with  the 
fact  that  the  shore  line  seems  to  have  remained 
unchanged  for  many  years,  may  be  accepted  as 
proof  that  a  littoral  current  whose  action  is  lim- 
ited by  the  adjacent  rocky  headlands,  operates 
to  prevent  the  further  encroachment  of  sedimen- 
tary deposits  and  to  maintain  the  beach  and 
neighboring  sea  bottom  as  they  exist  at  present. 

The  prevailing  winds  are  off-shore,  the  waves 
are  of  moderate  height  and  no  indications  of 
destructive  storms  from  the  sea  were  observed. 

The  rock  in  the  adjacent  hills  is  badly  disin- 
tegrated and  it  is  not  probable  that  much  ma- 
terial suitable  for  breakwaters  could  be  obtained 
from  them. 

Rio  Las  Lajas. 

The  lower  portion  of  the  Rio  Las  Lajas,  which 
lies  in  the  canal  belt,  is  in  the  dry  season  a 
quiet  lagoon  ranging  from  60  to  150  feet  in 
width  and  with  an  average  depth  of  about  12^^ 
feet.  In  some  places  it  has  cut  a  channel  in 
the  soft  rock  to  a  considerable  depth,  but  during 
most  of  its  length  it  seems  to  flow  through  earth. 
It  is  said  that  during  the  rainy  season  it  becomes 
a  large  stream  with  a  swift  current,  but  I  never 


APPENDIX  IV.— REPORT   OF  J.   W.   G.   WALKER,  ASSISTANT   ENGINEER 


351 


had  an  opportunity  of  observing  it  at  such  a 
time  and  the  rapidly  growing,  rank  vegetation 
upon  its  banks  speedily  oblitenates  all  signs  of 
high  water. 

Eio  Gbandb. 

The  Eio  Grande  is  formed  by  the  junction  of 
the  Rio  Cascabel  and  Canas  Gordas  creek  about 
nine-tenths  of  a  mile  southwest  of  the  point 
where  our  line  first  crosses  it.  These  tributary 
streams  rise  some  miles  southwest  and  south,  re- 
spectively, of  their  junction,  and  drain  a  consid- 
erable tract  of  country.  Frequent  outcrops  of 
rock  are  visible  in  the  banks  of  the  Rio  Grande 
from  its  origin  to  the  Tola  basin  and  again  at 
La  Flor,  although  the  bed  of  the  stream  is  usu- 
ally gravelly,  and  the  fact  that  these  outcrops 
occur  on  the  outsides  of  bends  seems  to  indicate 
that  the  present  river  is  meandering  between 
rocky  barriers  which  in  former  times  bounded  a 
much  larger  stream.  This  old  river  bed  has 
been  traced  by  Dr.  C.  W.  Hayes,  the  Geologist 
of  the  Commission,  from  the  upper  end  of  the 
gorge  of  the  Rio  Grande  to  a  point  about  three- 
quarters  of  a  mile  above  the  entrance  to  the  Tola 
basin.  It  varies  from  120  to  220  feet  in 
breadth  and  is  in  general  about  three  times  the 
width  of  the  present  river.  Whether  it  once 
carried  the  waters  of  Lake  Nicaragua  to  the  Pa- 
cific, as  has  been  suggested,  must,  with  the  in- 
formation now  at  our  command,  remain  a  matter 
of  conjecture,  but  it  is  a  plausible,  if  not  a  con- 
clusive, explanation. 

During  the  dry  season  the  upper  Rio  Grande 
practically  ceases  to  exist,  the  water  seeping 
from  pool  to  pool  through  intervening  bars  of 
gravel,  but  when  the  rains  begin  it  is  subject  to 
sudden  and  great  floods,  eroding  its  banks  and 
carrying  large  quantities  of  material  thus  exca- 
vated to  the  sea.    Some  of  the  tributary  streams. 


notably  Guachipilin  creek  and  the  Rio  Tola, 
discharge  water  during  the  entire  dry  season, 
and  it  is  probable  that  below  the  mouth  of  the 
latter  the  Rio  Grande  never  ceases  to  flow. 

Method  of  Conduotinq  Surveys. 

As  has  already  been  stated,  the  method 
adopted  was  to  run  a  main  line  following  sub- 
stantially the  Canal  Company's  low  level  loca- 
tion and  to  attach  to  this  such  lines  as  were  nec- 
essary for  an  accurate  determination  of  the  sur- 
rounding topography.  These  auxiliary  lines 
wherever  practicable,  were  so  disposed  as  to  form 
a  series  of  traverses  with  the  main  line,  thus  ea- 
abling  us  to  compiite  the  degree  of  accuracy 
with  which  our  work  was  performed  and  to  avoid 
carrying  forward  any  appreciable  error.  In 
general,  no  transit  work,  except  that  in  river 
beds,  was  considered  satisfactory  in  which  the 
error  exceeded  one  in  one  thousand  and  in  most 
cases  it  was  well  within  this  limit.  Thus  the 
curve  through  the  gorge  of  the  Rio  Grande,  the 
roughest  territory  which  we  encountered,  was 
tied  by  a  chord  joining  its  extremities,  foxing 
a  traverse  16,442  feet  in  length  in  which  the 
error  was  about  five  feet,  or  one  in  3288;  while 
a  traverse  17,030  feet  in  length  which  formed 
part  of  the  north  Tola  basin  meander  closed 
within  two  feet.  The  compass  was  used  to  some 
extent  on  short  and  unimportant  auxiliary  lines, 
but  nearly  all  the  work  was  done  with  transits, 
the  calculated  courses  being  carried  forward 
from  the  lake  and  the  needle  being  used  merely 
as  a  check. 

Obstacles  to  Survey. 

The  chief  obstacles  to  the  survey  during  the 
dry  season,  setting  aside  those  of  a  political  na- 
ture already  touched  upon,  were  the  denseness 
of  the  vegetation,  the  comparative  inefficiency 


352 


NICARAGUA  CANAL  COMMISSION 


of  native  labor,  the  prevalence  of  "pica-pica," 
a  plant  bearing  a  pod  which  sheds  a  dry,  irri- 
tating dust  almost  unendurable,  and  the  extra- 
ordinary number  of  wasps'  nests  encountered. 

During  the  wet  season  the  heavy  rains  and 
consequent  condition  of  the  country  rendered 
progress  slow  and  laborious. 


Result  of  Survey. 

The  result  of  our  survey  has  been  the  pro- 
duction of  a  map  which  is  believed  to  be  very  ac- 
curate, and  from  which,  in  connection  with  the 
reports  of  the  Commission's  geologist  and  hydro- 
grapher,  all  data  necessary  for  an  intelligent 
comparison  of  alternate  routes  may  be  obtained. 


Personnel. 

I  give  below  a  statement  of  the  assistants  employed  upon  this  work,  together  with  the  dates 

uj)on  which  they  joined  and  left  my  party. 


Name. 

E.  B.  Harden, 
M.  A.  Coroalles, 

F.  H.  Davis, 
J.  D.  Forster, 
II.  C.  Ilurd, 

C.  P.  E.  Peugnet, 
P.  H.  Belknap, 
J.  A.  Bull, 
Fred.  Davis, 
E.  P.  IIum})hrey, 
L.  R.  Lee, 
O.  B.  Powell, 
A.  L.  Scott, 


OcciiiMition. 

Assistant  Engineer, 

Instrumentman, 

Instrumentman, 

Inst  ni  men  tman, 

Instrumentman, 

Instrumentman, 

Assistant, 

Assistant, 

A  ssistant. 

Assistant, 

Assistant, 

Assistant, 

Assistant, 


Joined. 

Dec.  21,  1897 
Dec.  21,  1897 
Jan.  27,  1898 
Dec.  21,  1897 
Dec. '21,  1897 
Dec.  21,  1897 
Dec.  21,  1897 
Dec.  21,  1897 
Feb.  12,  1898 
Mch.  2,  1898; 
Dec.  21,  1897; 
Dc>c.  21,  1897; 
Feb.  17,  1898; 


Loft. 

Sept.  22,  1898. 
Sept.  22,  1898. 
Apr.  30,  1898. 
Feb.  12,  1898. 
Sept.  21,  1898. 
May  14,  1898. 
Apr.'8,  1898. 
Jan.  21,  1898. 
Sept.  17,  1898. 
May  14,  1898. 
JulV  23,  1898. 
June  14,  1898. 
Apr.  30,  1898. 


Distance  Run. 
The  total  amount  of  line  run  was  304.G  miles, 
which  may  be  divided  as  follows:  muos. 

Main  Line 17.489 

Cross  sections 100.115 

Rio  Grande  meander 21.512 

Canas  Gordas  meander 977 

Rio  Grande  and  Caiias  Gordas  oflF- 

•sets 13.907 

North  Tola  basin  meander 14.370 

Lines  for  topography 36.864 

South  Tola  basin  meander 5.315 

Lines  for  topography 8.254 

Rio  Grande  diversion  meander.  .  .      5.116 

Lines  for  topography 24.387 

Random  line^  for  topography  ....    56.295 

Total 304.601 


Alternate  Routes. 

Four  routes  between  Lake  Nicaragua  and 
Brito  have  been  proposed  and  their  relative  de- 
fects and  advantages  will  be  briefly  discussed 
in  the  following  paragraphs. 

HVDROGEAPHIO    CONSIDERATIONS, 
t 

In  order  to  make  intelligent  comparison  of 
these  alternate  routes  an  understanding  of  the 
functions  to  be  performed  by  the  canal  is  essen- 
tial. The  chief  of  these  is,  of  course,  the  reten- 
tion in  a  state  of  comparative  repose,  of  a  body 
of  water  sufficiently  deep  and  broad  to  permit 
the  passage  of  shipping,  and  as  every  canal  is  to 


APPENDIX  IV.— REPORT   OF  J.   W.   G.   WALKER,   ASSISTANT   ENGINEER 


353 


a  certain  extent  a  drain,  its  usefulness  for  pur- 
poses of  navigation  depends  upon  the  amount  of 
water  which  passes  into  or  through  it  and  upon 
the  possibility  of  regulating  the  height  and  ve- 
locity of  this  water  within  certain  well-defined 
limits.  A  knowledge  of  the  fluctuations  of  the 
lake  level  and  of  the  steps  which  must  be  taken 
to  regulate  it  is  therefore  indispensable,  and  it  is 
in  this  kind  of  information  that  the  Maritime 
Canal  Company  seems  to  have  been  deficient. 

Mr.  A.  P.  Davis,  the  Commission's  hydro- 
grapher,  reports  that  in  order  to  control  the  lake 
within  a  five-foot  limit — that  is,  between  eleva- 
tions of  105  and  110  feet  above  the  level  of  the 
Caribbean  sea,  or  106  and  111  feet  above  the 
level  of  the  Pacific  ocean — a  spillway  having  a 
capacity  of  50,000  ciibic  feet  per  second  for  183 
days  oiit  of  the  year  should  be  provided.  As 
the  distance  from  the  present  outlet  of  the  lake 
to  the  highest  location  which  has  been  suggested 
for  regulating  works  on  the  Eio  San  Juan 
is  considerable  and  as  the  channel  of  the  river 
is  tortuous,  it  seems  desirable  to  drain  a  large 
part  of  the  superfluous  lake  water  through  the 
Western  Di\nde  into  the  Pacific  ocean.  "No  low 
pass  in  the  divide  at  a  reasonable  distance  from 
the  lake  is  available  for  a  separate  waste-way  and 
we  are  therefore  constrained  to  so  increase  the 
area  of  the  cross  section  of  our  summit  level  cut 
as  to  permit  its  use  both  as  canal  and  waste-way. 
The  Commission's  location  is  such  that  one  chan- 
nel will  serve  both  purposes,  the  water  not 
needed  for  the  canal  being  discharged  through 
regulating  works  situated  at  a  distance  of  9.8 
miles  from  the  lake. 

Eio  Medio  Route. 

This  route  follows  the  vallev  of  the  Rio 
Medio  from  the  lake,  crosses  the  divide  at  an 
elevation  of  about  243  feet  above  the  sea,  enters 

23 


the  valley  of  the  Rio  Grande  near  the  mouth  of 
Guachipilin  creek  and  passes  through  the  Tola 
basin  and  La  Flor  hills  to  Brito.  This  roiite 
mav  be  dismissed  as  involving  verv  heavv  ex- 
cavation  without  accomplishing  its  object  of 
avoiding  the  Rio  Grande,  which,  if  used  as  a 
waste-way,  would  be  so  augmented  by  the  drain- 
age of  the  lake  as  to  make  impracticable  the  pro- 
ject of  conducting  both  it  and  the  canal  in  sepa- 
rate channels  through  the  valley  between  Gua- 
chipilin creek  and  the  Tola  basin. 

Canal  Company's  Low-Level  Route. 

The  second  route,  known  as  the  Canal  Com- 
pany's Low-level  Location,  leaves  the  lake  900 
feet  north  of  the  mouth  of  the  Rio  Las  Lajas  and 
runs  south  61  ^^  west  up  the  valley  of  this  stream, 
which  it  crosses -four  times  within  6800  feet. 
Beyond  the  last  crossing  it  continues  in  the  same 
direction  up  the  valley  of  Guiscoyol  creek  to  a 
point  19,700  feet  from  the  lake,  where  it  curves 
gently  northward,  crosses  the  Continental  Divide 
at  an  elevation  of  154  feet  above  the  sea  and 
at  a  distance  of  five  miles  from  the  lake  and  en- 
ters the  valley  of  the  Rio  Grande.  It  follows 
this  stream  through  its  gorge,  curving  first  north- 
ward and  then  westward,  and  emerging  with  a 
westerly  bearing  upon  a  small  plain  at  the 
mouth  of  Guachipilin  creek,  sweeps  northward 
again  to  the  first  lock  site  about  2500  feet  be- 
yond the  creek  crossing.  From  this  point  the 
line  follows  the  right  bank  of  the  Rio  Grande  to 
Brito,  cutting  off  an  occasional  bend  and  termi- 
nating near  Brito  Head.  Four  locks  were  con- 
templated, the  first,  already  referred  to,  having 
a  descent  of  25  feet;  the  second  and  third,  situ- 
ated in  the  upper  part  of  the  Tola  basin  10.8 
miles  from  the  lake,  and  at  La  Flor  14.4  miles 
from  the  lake,  respectively,  having  a  fall  of  30 
feet  each ;  and  the  fourth,  about  6000  feet  from 


354 


NICARAGUA  CANAL  COMMISSION 


the  beach  at  Brito,  having  a  fall  of  25  feet  at 
mean  tide  or  29^  feet  at  low  tide.  The  total 
distance  from  the  lake  to  the  beach  at  Brito  is 
about  17.4  miles  and  the  maximum  curve  has  a 
radius  of  4297  feet. 

The  inadequacy  of  the  works  proposed  by  the 
Canal  Company  is  apparent  upon  examination. 
The  cross  section  of  their  summit  level  cutting 
is  so  small  as  to  make  its  effective  use  as  a  waste- 
way  impracticable,  while  the  fact  that  the  level 
of  the  lake,  even  with  ample  regulating  facili- 
ties, will  at  certain  times  not  exceed  106  feet 
above  the  sea,  would  reduce  the  minimum  depth 
of  water  in  this  portion  of  the  canal  to  26  feet. 
Even  with  suitable  modifications  of  design  this 
route  is  open  to  some  objections,  the  chief  ones 
being  the  unnecessary  length  of  line  and  the  im- 
possibility of  avoiding  taking  the  flood  waters  of 
the  Kio  Tola  into  the  canal  below  the  regulating 
works. 

Canal  Company's  Hioh-Level  Location. 

The  third  route,  known  as  the  Canal  Com- 
pany's High-Level  Location,  is  identical  with 
the  preceding  to  a  point  8.4  miles  from  the  lake 
and  near  the  crossing  of  Guachipilin  creek. 
Here  the  two  lines  separate,  the  one  now  under 
consideration  following  the  general  course  of  the 
river  and  entering  the  Tola  basin,  which  is  to  be 
made  a  part  of  the  summit  level  by  means  of  a 
dam  closing  the  gap  in  the  hills  at  La  Flor 
through  which  the  Rio  Grande  now  flows.  This 
dam  must  have  a  length  of  2000  feet  on  the  crest 
and  must  rise  to  a  height  exceeding  111  feet 
above  the  sea,  71  feet  above  the  general  plain 
of  the  valley,  and  88  feet  above  the  bed  of  the 
Kio  Grande  at  this  point.  Kecent  borings  by 
the  Commission  show  that  a  suitable  foundation 
may  be  obtained  at  an  elevation  of  40  feet  below 
sea  level ;  hence  the  height  of  a  dam  at  this  point. 


from  foundation  to  crest,  would  exceed  151  feet. 
The  Canal  Company  proposes  to  place  a  weir  iu 
the  saddle  of  an  adjacent  hill  and  by  this  means 
to  discharge  the  drainage  of  the  valley  and  about 
60  per  cent,  of  the  surplus  discharge  of  the  lake 
watershed.  Two  locks  of  42i  feet  fall  each,  are 
to  be  placed  in  the  rocky  spur  southwest  of  the 
western  end  of  the  dam  and  14.36  miles  from 
the  lake,  and  from  this  point  the  line  continues 
in  a  tangent  to  Brito,  passing  through  the  lock 
site  6000  feet  from  the  beach  mentioned  in  the 
description  of  the  Canal  Company's  Low-Level 
Line,  and  which  in  this  line  is  also  the  site  of  a 
proposed  lock  with  a  fall  of  25  feet  at  mean  tide 
or  29i  feet  at  low  tide.  The  total  distance  from 
the  lake  to  the  beach  at  Brito  by  this  route  is 
17.4  miles  and  the  maximum  curve  has  a  radius 
of  4297  feet. 

The  advantages  claimed  for  this  plan  are  the 
addition  of  4.6  miles  of  free  navigation  to  the 
summit  level,  the  saving  of  canal  excavation  for 
this  distance,  the  formation  of  an  inland  harbor 
4000  acres  in  extent,  and  the  satisfactory  dis- 
position of  the  drainage  of  the  Eio  Tola.  The 
fact  that  the  adoption  of  a  high-level  line  would 
l)ermit  the  waste  of  lake  water  through  a  chan- 
nel at  a  greater  distance  from  the  canal  at  La 
Flor  than  would  otherwise  be  practicable,  is  also 
worthv  of  consideration. 

The  disadvantages  are  the  magnitude  of  the 
dam,  the  depth  of  foundations,  the  difficulty  of 
disposing  of  the  drainage  of  the  valley  during 
construction,  the  possibility  of  the  failure  of  the 
stnicture,  with  all  its  attendant  evils,  the  exees- 
sive  fall  of  the  locks,  and  the  imnecessary  length 
of  line. 

The  works  proposed  by  the  Canal  Company 
are  unsuitable  for  the  conditions  which  we  now 
know  to  exist,  for  reasons  given  in  the  discus- 
sion of  their  low-level  route. 


APPENDIX   IV.— REPORT   OF  J.   W.   G.   WALKER,  ASSISTANT  ENGINEER 


355 


NiCABAGUA  Canal  Commission's  Location. 

The  fourth  route,  which  is  recommended  by 
this  Commission,  is  identical  with  the  two  pre- 
ceding locations  from  the  initial  point  to  the 
place  where  they  diverge,  8.4  miles  from  the 
lake.  Here  the  Commission's  line  curves  to  the 
northward,  follows  the  left  side  of  the  valley  of 
the  Eio  Grande,  enters  the  Tola  basin  at  the 
base  of  the  hills  which  bound  it  on  the  south, 
curves  around  these  hills  to  the  left  and,  travers- 
ing a  part  of  the  alluvial  plain  which  indents  the 
high  land  to  the  south,  crosses  a  spur  of  the  La 
Flor  hills  to  the  left  of  the  Rio  Grande  and 
emerges  from  the  basin.  Fifteen  hundred  feet 
beyond  it  curves  to  the  left,  crosses  the  river 
twice,  sweeps  to  the  right  at  the  base  of  one  of  ' 
the  range  of  hills  bounding  the  valley  on  the 
southeast  and  runs  to  the  beach  in  a  direction 
approximately  parallel  to  the  lines  already  dis- 
cussed. 

It  is  proposed  to  construct  a  low-level  canal 
along  this  location,  the  summit  level  being  of 
such  dimensions  as  shall  allow  of  its  use  both  as 
waste- way  and  canal.  At  a  point  9.8  miles  from 
the  lake  regulating  works  would  be  constructed 
and  the  surplus  water  discharged  into  a  channel 
north  of  the  canal.  This  channel  would  be  ex- 
cavated artificially,  but  it  is  thought  that  the 
water,  which  would  be  under  control,  might  be 
relied  upon  to  enlarge  it  from  a  small  cutting 
to  the  required  size.  The  bed  of  the  Rio 
Grande  is  to  be  utilized  wherever  practicable. 
The  first  lock  would  be  situated  just  below  the 
regulating  works  and  10.2  miles  from  the  lake, 
the  location  of  the  others  depending  upon  the 
number  decided  upon. 

The  chief  advantages  of  this  route  for  a  low- 
level  canal  are  its  length,  which  is  16.9  miles,  or 
one-half  mile  less  than  either  of  the  Canal  Com- 
pany's locations,  its  avoidance  of  the  flood  waters 


of  the  Tola,  which  would  enter  the  waste-way  to 
the  north  of  the  proposed  canal,  and  the  great 
number  of  good  natural  lock  sites  over  which  it 
passes.  The  maximum  curve  has  a  radius  of 
4297  feet. 

Our  recently  acquired  hydrographic  informa- 
tion demonstrates  the  impracticability  of  di- 
verting the  upper  Rio  Grande  as  proposed  by 
the  Canal  Company,  and  the  reception  of  its 
flood  waters  into  the  summit  level  of  the  canal 
is  contemplated. 

General. 

The  following  general  observations  and  sug- 
gestions are  submitted  as  having  a  more  or  less 
direct  bearing  upon  the  problem  of  canal  con- 
struction. 

Labob. — The  labor  supply  upon  the  western 
division  is  insufficient  and  unsuitable  for  the 
prosecution  of  an  engineering  work  of  magni- 
tude. The  natives  are  indolent,  although  prob- 
ably not  more  so  than  other  inhabitants  of  the 
tropics,  and  are  unaccustomed  to  and  unfitted 
for  arduous  labor.  If  well  treated  and  pro- 
tected from  arbitrary  arrest  and  conscription, 
they  would  be  available  in  limited  numbers  for 
comparatively  light  work,  but  the  greater  part 
of  the  labor  supply  must  be  obtained  elsewhere. 

Health. — The  health  of  my  party  v^BiSy  upon 
the  whole,  excellent  and  I  believe  the  climate 
to  be  a  good  one.  The  most  prevalent  diseases 
are  malarial  fevers,  which  are  common  among 
the  lower  classes  during  the  rainy  season,  but 
which  need  not  be  greatly  feared  by  those  able 
and  willing  to  take  care  of  themselves.  I  am 
inclined  to  think  that  dissipation,  due  to  a  lack 
of  the  resources  and  restraints  of  home,  is  ac- 
countable for  much  of  the  fever  from  which 
strangers  suffer. 

Food   Supply. — Although   the  present   food 


356 


NICARAGUA  CANAL  COMMISSION 


supply  is  only  sufficient  to  sustain  the  present 
population,  an  increased  demand  would  prob- 
ably result  in  an  adequate  supply  of  corn,  beans, 
and  plantains.  Other  foods,  with  the  exception 
of  beef,  which  is  plentiful  but  poor,  would  have 
to  be  imported. 

Water  Supply. — The  only  considerable 
quantities  of  good  water  between  Lake  Nica- 
ragua and  the  Pacific  ocean,  which  are  available 
during  the  dry  season,  come  from  Guachipilin 
creek,  Chocolata  creek  and  the  Rio  Tola. 
Throughout  most  of  the  canal  line  some  system 
of  water  works  would  have  to  be  established. 

Fuel. — Wood  is  abundant  and  may  be  had 
for  the  cutting.  Coal  would  have  to  be  im- 
ported. 

Luo). — As  far  as  I  have  been  able  to  deter- 
mine, two  hundred  pesos  per  cavalleria  is 
a  fair  average  price  for  unimproved  land  bought 
in  large  tracts.  Assuming  exchange  at  2.50 
that  would  be  seventy-one  and  four-tenths  cents 
per  acre.  Cleared  or  cultivated  land  is,  of 
course,  worth  much  more. 

Assuming  that  strips  of  land  1200  feet  wide 
are  required  for  canal  and  waste-way  respect- 
ively, the  quantities  appropriated  for  the  works, 
exclusive  of  Brito  harbor,  would  be  approxi- 
matelv  as  follows: 

Nicaragua  Canal  Commission's  line,  3350 
acres;  Nicaragua  Canal  Co.'s  high-level  line, 
5985  acres;  Nicaragua  Canal  Co.'s  low-level 
line,  3280  acres. 

It  is  assumed  that  the  whole  Rio  Grande  val- 
ley below  the  lower  end  of  the  Commission's 
proposed  tide  lock  would  be  needed  for  Brito 
harbor.  Its  area  is  approximately  fiCl  acres  and 
the  land  is  at  present  valueless. 

Hubs. — ^Hubs  and  bench  marks  in  future  sur- 
veys should  be  made  of  imperishable  material 
and  buried  slightly  beneath  the  surface  of  the 


ground  to  guard  against  their  destruction  by  the 
extensive  fires  which  rage  during  every  dry 
season.  If  wood  is  used  it  should  be  carefully 
selected,  as  most  varieties  rot  rapidly  in  that 
climate. 

Roads. — The  best  roads  are  but  rough  tracks 
in  the  dry  season  and  are  practically  impassable 
except  for  horsemen  during  the  rains.  They 
might  readily  be  improved,  however,  as  semi- 
disintegrated  rock  is  plentiful  and  easily 
handled. 

Police  System. — An  efficient  poUce  force, 
quite  independent  of  the  local  authorities, 
should  be  established  at  the  beginning  of  con- 
struction and  should  rigorously  enforce  order 
'  and  a  compliance  with  sanitary  regulations.  The 
sale  of  liquor  on  or  near  the  work  should  be 
prohibited. 

Postal  System. — A  postal  service  should  be 
maintained  for  the  use  of  those  engaged  upon 
the  work,  and  in  no  case  should  the  mail  bags 
leave  the  hands  of  responsible  American  em- 
ployees. 

^Monopolies. — It  is  the  policy  of  the  Xica- 
raguan  Government  to  increase  its  revenues  by 
selling  or  leasing  to  corporations,  firms,  or  indi- 
viduals, the  exclusive  right  to  pursue  certain 
profitable  industries.  Thus  the  steam  naviga- 
tion of  the  Eio  San  Juan  and  Lake  Nicaragua  is 
monopolized  by  one  company,  a  percentage  on 
the  price  of  beef  killed  for  sale  in  the  depart- 
ment of  Eivas  must  be  paid  to  the  owner  of  a 
concession,  and  all  freight  landed  at  San  Juan 
del  Sur  must  pass  over  a  wharf  whose  owner  is 
legally  protected  from  the  annoyances  of  com- 
petition. 

The  existence  of  this  system  should  be  borne 
in  mind  and  a  definite  understanding  should  be 
reached  with  the  Government  and  w^ith  the  hold- 
ers of  such  concessions  by  which   obstructing 


APPENDIX   IV.— REPORT   OF  J.   W.   G.   WALKER,   ASSISTANT   ENGINEER 


357 


rights  shall   be   waived   or  reasonable   charges 
guaranteed. 

Earthquakes. — At  about  half-past  ten  on  the 
morning  of  April  29,  1808,  while  we  wei*e  en- 
camped at  La  Flor,  there  was  an  earthquake  of 
considerable  violence  but  of  brief  duration.  I 
at  once  examined  several  steep-cut  river  banks 
in  the  neighborhood  but  they  apparently  had 
suffered  no  change,  ^o  harm  was  done  at 
Kivas,  although  in  Granada  and  Managua  some 
walls  were  slightly  cracked.  The  canal  belt 
seems  to  lie  in  a  favored  region  where  such  dis- 
turbances are  never  serious. 

Conclusion. 

Upon  the  completion  of  my  field  work  I  re- 
turned to  the  United  States  and  reported  for 


duty  at  the  Washington  office  on  the  27th  of 
last  October.  Since  that  time  I  have  been  em- 
ployed upon  general  office  work  and  in  the 
preparation  of  estimates  of  which  you  have  been 
furnished  copies. 

In  conclusion  I  wish  to  express  my  apprecia- 
tion of  the  services  rendered  bv  the  members  of 
my  field  party,  and  especially  by  Mr.  E.  B. 
Harden,  w^ho  was  attached  to  my  party  at  his 
own  request,  and  to  whose  skill  and  unflagging 
energy  is  due  much  of  the  excellence  of  the  map. 

Yerj'  respectfully, 

J.  W.  G.  Walker, 
Civil  Engineer,  U.  S.  X., 

Assistant  Engineer. 


APPENDIX  V 


REPORT 


ON 


SAN  JUAN  RIVER  AND  LAKE  NICARAGUA 


BY 

FRANCIS  LEE  STUART 

Assistant  Engineer 


CONTENTS 

Report  on  Topographic  axd  Hydroorapiiic  Survey  of  San  Juan  River. 

PAGE 

Scope  of  Survey 363 

General  Character  of  River 363 

Details    364 

The  Bends  of  the  San  Jiian 366 

Machuca  Dam  Site ' 366 

The  Tributaries  of  the  San  Juan 366 

Fluctuation 366 

Winds 367 

Rocks 367 

Timber   367 

Trees  Suitable  for  Piles  in  Sea 367 

Present  Land  Values  and  Facilities 367 

Rainfall    368 

Climate 368 

Labor    368 

PoUtical  Division 368 

Deduction  as  to  Canal  Field 369 

Value  of  Survey 369 

Suggestions 369 

Methods  of  Survey 369 

Members  of  Party 370 

Report  on  Survey  of  Lake  Nicaragua. 

Scope  of  Survey 371 

Location   371 

Bottom  of  Lake 371 

Watershed 372 

Fluctuations   372 

Principal  Tributaries 372 

Islands    372 

Shore    373 


362  NICARAGUA  CANAL  COMMISSION 

PAOB 

Winds 373 

Waves 374 

Anchorages 374 

Sailing  Route  of  Canal 374 

Land  Values 374 

Climate 374 

Labor 374 

Method  of  Survey 374 

Members  of  Party 374 

Work  in  United  States. 

Summit  Level 375 

Storage  Capacity 375 

Velocities  in  Eiver  and  Canal 377 

Tables  of  Velocities 377 

Submerged  Area 377 

Curve  Widening   377 

Estimates    378 

Side  Slopes 378 

Lake    378 

Increased  width  on  Curves 378 

Revisions  of  Location 378 

Cut-oifs 378 

Lock  Systems 378 

Variants    379 

Narrow  Canal  Estimates 379 

Sketches   379 

Value  of  Estimates 379 

Sailing  Route  in  Lake 379 

Canal  Line  in  River 380 

Arguments  For  and  Against 380 

Variants  6A  and  6Z 380 

Letter  on  Levels  on  San  Juan  River 381 

Memorandum  of  Distances  and  Levels  on  San  Juan    382 

Sketches  of  Variants 385 


APPENDIX  V 


W^vsmNOTON,  D.  C,  April  15,  1899. 

Me.  E.  S.  Wheeleb, 

Chief  Engineer  to  Nicaragua  Canal  Commis- 
sion, Washington,  D.  C. 

Sir: — December  the  I7th,  1897,  upon  arriv- 
ing in  Greytown  I  was  put  in  charge  of  one  of 
the  Precise  Level  parties.  After  breaking  out 
an  outfit  and  adjusting  instruments,  etc.,  I  was 
directed  to  proceed  to  San  Carlos  and  take  charge 
of  the  survey  of  the  San  Juan  river. 

Upon  completion  of  this  survey  I  was  in- 
structed to  make  a  triangulation  and  hydro- 
graphic  survey  of  Lake  Nicaragua. 

I  have  the  honor  to  submit  the  following  re- 
ports: 

Topographic  and  Hydrogbaphio  Survey  of 
THE  San  Juan  River  from  Lake  Nicaragua 
to  the  Caribbean  Sea. 

Scope  of  Survey.— In  January  we  measured 
a  base  line  15,044  feet  long  near  San  Carlos  for 
the  use  of  the  hydrographic  party  then  making 
a  survey  of  that  portion  of  Lake  Nicaragua 
which  lies  between  the  Solentiname  islands  and 
San  Carlos  where  the  lake  discharges  into  the 
San  Juan  river. 

On  January  the  29th,  1898,  we  began  the  sur- 
veys of  the  San  Juan  river  using  station  A  of  the 
hydrographic  base  line  located  at  the  southwest 
corner  of  San  Carlos  Morro  as  the  zero  of  sur- 
vey, and  the  top  of  inshore  end  of  old  boiler  in 


Lake  Nicaragua,  elevation  109.75,  for  the  basis 
of  our  levels. 

We  carried  the  stadia  line,  the  line  of  levels, 
and  the  topography  of  the  banks  as  far  as 
Punta  Gorda,  Lieut.  G.  C.  Ilanus,  U.  S.  N.,  in 
charge  of  the  naval  party,  making  the  hydro- 
graphic  survey  of  this  portion. 

From  Punta  Gorda,  Lieut  Hanus  and  party 
having  been  recalled  to  the  United  States  for 
other  duties,  we  took  up  his  work  as  well  and 
carried  the  entire  survey  to  the  San  Francisco 
river.  At  the  San  Francisco  river,  jumping 
around  twelve  miles  previously  surveyed  by  this 
Commission,  we  took  up  the  survey  again  at  the 
Los  Cuellos  islands  and  completed  the  survey  of 
the  San  Juan  to  a  point  12^  miles  from  Grey- 
town,  where  we  connected  with  the  survey  of 
Assistant  Engineer  Andrew  Onderdonk. 

From  the  junction  of  the  San  Juan  and  Colo- 
rado rivers  we  also  completed  a  survey  down  the 
Colorado  river  to  the  sea,  including  a  survey  of 
the  Cano  Bravo. 

From  the  Parado  creek  on  the  San  Juan  we 
also  ran  a  direct  line  to  the  nearest  point  on  the 
sea. 

A  special  investigation  was  made  at  Machuca 
for  a  dam  site. 

General  Characteristics  of  the  River. 

The  San  Juan  is  formed  by  the  discharge  of 
the  Lake  Nicaragua  watershed  and  finds  its  way 


364 


NICARAGUA   CANAL  COMMISSION 


to  the  Caribbean  sea  tliroiigli  the  lower  tliird  of 
the  Xicaragiian  depression  or  valley,  which  be- 
gins at  the  headwaters  of  the  Sinicapa  river  in 
the  northwestern  end  of  Nicaragua  and  runs 
southeasterly  to  the  sea  at  Greytown.  The  San 
Juan  valley  is  narrow,  with  water-parting  lines 
considerably  closer  to  the  river  on  the  north 
side  than  on  the  south. 

The  river  bottom  presents  four  distinct  and 
peculiar  features: 

1st.  From  the  outlet  of  the  lake  to  the  trap- 
rocks  of  Castillo  it  is  at  present  flowing  in  an 
opposite  direction  from  its  old  course,  which  was 
to  the  Pacific  through  an  older  channel  that  has 
been  partially  silted  up. 

2d.  From  Castillo  to  Machuca  it  flows  over  a 
rockv  bed  which  does  not  show  evidence  of  an 
older  channel,  its  present  cut  through  the  old 
divide  having  been  made  since  the  lake  began 
to  flow  into  the  Caribbean  sea. 

3d.  From  Machuca  to  the  mouth  of  the  San 
Carlos  river  it  flows  in  an  old  river  bed  not  yet 
silted  up.  That  this  old  bed  is  at  or  l>elow"  sea 
level  is  a  striking  evidence  that  a  subsidence  of 
the  region  has  taken  place. 

4th.  From  the  mouth  of  the  San  Carlos  river 
to  the  sea  the  old  bed  continues  sinking  deeper, 
but  a  great  quantity  of  volcanic  sand  from  the 
Costa  Rican  mountains  has  been  deposited  by 
the  San  Carlos  river,  filling  up  the  old  channel 
and  forming  an  entirely  new  and  much  flatter 
gradient  for  the  present  river  bt^d. 

Detaii^. — From  San  Carlos  to  the  Savalos 
river  at  the  head  of  the  Toro  rapids,  a  distance 
of  27.16  miles,  the  river  falls  5.4  feet,  the  banks 
are  flat  with  low  open  marshes  extending  back  a 
considerable  distance  on  both  sides  of  the  river. 
These  marshes  are  covered  with  water  except  at 
a  very  low  stage  of  the  river.    * 

The  banks  of  the  river  below  the  water  sur- 


face are  steep,  seem  to  hold  well,  are  regular, 
and  of  about  a  uniform  depth.  The  hills  rise 
very  abruptly  upon  the  confines  of  the  marshes 
and  except  for  a  stretch  of  half  a  mile  at  Mel- 
chora  there  is  no  ground  which  gently  slopes  to 
tlie  river  level,  a  slope  of  more  than  5°  l>eing 
the  dominant  characteristic  of  this  section.  At 
Martinez,  San  Francisco,  Palo  de  Arco,  and 
Savalos  ranches,  the  cattle  feed  in  the  marsh 
during  the  dry  season,  in  from  1^  to  2i  feet  of 
water.  One  thousand  acres  covers  about  all  the 
land  so  used  which  came  under  our  obser\'ation. 

Foivst  trees  are  sparse,  the  vegetation  of  the 
swamps  being  chiefly  palms,  bushes  and  vines. 
There  are  seven  hills  which  are  close  to  the 
river,  but  none  give  evidence  of  serviceable  rock 
for  building  purposes,  except  a  ridge  of  moun- 
tains which  rises  from  the  swamps  wuthin  a  mile 
of  the  river  at  Isla  Grande.  This  ridge  also  has 
some  timber  on  it. 

In  this  section  the  old  bed  of  the  river  may 
have  been  anywhere  in  this  valley,  the  present 
conditions  giving  evidence  that  the  old  topog- 
raphy has  been  drowned,  except  the  hills,  and 
that  the  present  bed  of  the  river  and  the  level 
ground,  such  as  marshes  and  swamj^,  has  been 
made  by  the  river  in  comparatively  recent  times. 

From  the  Savalos  river  to  the  foot  of  the  Toro 
rapids  the  river  falls  7.3  feet  in  1.7  miles  be- 
tween a  series  of  hills  on  the  south  bank,  and  one 
hill  and  low  ground  on  the  north. 

From  the  foot  of  the  Toro  to  the  beginning  of 
the  Castillo  rapids  the  river  falls  1.2  feet  in  7.08 
miles.  The  valley  gradually  narrows  until  it  is 
some  3000  feet  wide  between  the  hills  at  the 
rapids.  This  section  has  the  same  characteris- 
tics as  the  section  above  the  Toro,  except  J;hat 
there  are  no  open  marshes  but  swamps.  At 
Castillo  the  river  falls  G  feet  in  2000  feet,  over 
apparent  boulders  and  rocks. 


APPENDIX   v.— REPORT   OF   F.   L.    STUART,   ASSISTANT   ENGINEER 


365- 


The  village  of  Castillo  consists  of  about  50 
frame  and  cane  houses,  these  being  between  six 
and  eight  feet  above  the  river  on  the  one  street 
of  the  town.  The  principal  are  the  two  frame 
warehouses  belonging  to  the  C.  &  P.  Transit 
Co.,  one  eight  feet  above  the  wat<?r  and  the  other 
four. 

The  Xicaraguan  Government  frame  ware- 
house is  six  feet  above  the  water,  and  a  custom 
house  about  eight  feet.  The  custom  house  also 
contains  barracks  for  soldiers,  which  are  always 
kept  at  this  point,  an  old  fort  on  the  hill  above 
the  town  being  still  in  service. 

The  rapids  at  this  point  are  so  shallow  that  all 
freight  brought  by  river  steamers,  except  dur- 
ing very  high  water,  is  transported  on  a  tram- 
road,  which  runs  through  the  only  street  of  the 
town,  and  connects  the  two  warehouses  of  the 
Transit  Company. 

From  the  bottom  of  Castillo  rapids  to  Punta 
Gorda  the  river  falls  2.5  feet  in  2.08  miles.  In 
this  distance  there  are  three  small  houses  on  the 
river  bank. 

From  Punta  Gorda  to  a  mile  below  Machuca 
rapids,  a  distance  of  10.62  miles,  the  river  falls 
26  feet  over  a  succession  of  short  rapids,  the 
Mica,  Balas,  Patricia,  Infernito  and  Machuca. 
The  valley  is  narrow  and  well-defined,  the  hills 
on  either  side  forming  the  banks,  the  bottom  of 
the  river  being  chiefly  rock.  But  two  clearings 
or  houses  are  visible  from  the  river. 

From  a  point  one  mile  below  Machuca  to  the 
mouth  of  the  San  Carlos  river,  a  distance  of 
14.79  miles,  the  river  falls  1.0  feet.  This  sec- 
tion is  called  Agiia  Muerta  (dead  water)  and  is 
the  best  defined  river  bed  on  the  San  Juan. 
The  hills  on  both  banks  make  a  narrow,  well-de- 
fined valley  and  exclude  the  idea  that  the  river 
could  ever  have  been  in  any  other  position  in 
this  section  than  where  it  is  now.     The  river  is 


nan*ow  and  from  18  to  50  feet  deep  with  rock 
bottom  at  points.  The  banks  are  well  w^ooded 
and  there  is  rock  suitable  for  small  rubble  work 
in  some  of  the  surrounding  hills.  There  is  but 
little  swamp  land,  and  that  only  in  small  pockets. 

From  the  mouth  of  the  San  Carlos  to  the  San 
Juanillo  river,  a  distance  of  33.02  miles,  the  fall 
is  30  feet.  The  character  of  the  river  changes, 
and  the  bottom  is  entirely  shifting  sand  to  a 
considerable  depth.  The  banks  are  of  alluvial 
material,  and  there  is  other  evidence  of  a 
drowned  topography.  The  hills  in  this  section 
are  of  no  great  height,  generally  from  a  hundred 
to  two  hundred  feet  above  sea  level.  There  are 
scattering  clearings  and  houses  along  this  sec- 
tion, the  principal  being  at  the  mouth  of  the 
San  Carlos,  Palo  Seco  and  Eemolinita. 

At  the  San  Juanillo  we  enter  the  coastal  or 
delta  plain  which  spreads  fan-shaped  to  the  sea. 
The  north  confines  of  this  plain  are  the  San 
Juanillo  and  Juan  rivers,  and  to  the  south  the 
Colorado  river.  The  general  slope  of  this  plain 
to  the  sea  is  about  one  foot  and  a  half  to  the 
mile,  and  is  at  a  height  of  about  extreme  high 
water  of  the  rivers  which  meander  through  it. 
It  is  dotted  here  and  there  with  islands,  lagoons 
and  partially  drowned  hills.  The  forest  consists 
of  Silico  and  other  palms  with  a  few  scattering 
hard-wood  trees. 

The  distance  from  the  San  Juanillo  to  the 
junction  of  the  San  Juan  and  Colorado  rivers  is 
5.28  miles,  and  the  fall  4  feet.  From  this  junc- 
tion to  the  sea,  via  the  San  Juan,  the  distance  is 
18.65  miles  and  the  fall  21  feet.  From  this 
junction  via  the  San  Juan  to  Parada  creek  and 
thence  in  a  straight  line  across  the  swamps  and 
lagoons  to  the  sea,  the  distance  is  12.03  miles. 
From  the  junction  to  the  sea,  via  the  Colorado 
river  alone,  the  distance  is  23.7  miles,  and  via 
the  Colorado  river  and  Cano  Bravo  the  distance 


366 


NICARAGUA  CANAL  COMMISSION 


is  19.7  miles.  This  part  of  the  coastal  plain, 
through  which  the  Colorado  and  Bravo  flow,  is 
almost  entirely  composed  of  islands  and  lagoons 
up  to  the  foot  of  tlie  Costa  Rica  hills,  which  rise 
to  the  south  side  of  this  river  and  which  are  the 
onlv  hills  visible  in  this  section.  There  are  scat- 
tering  forest  trees  on  the  Costa  Rica  hills  and 
some  rock  suitable  for  rock-filling  work.  There 
are  but  two  houses  between  the  junction  and 
Colorado  bar. 

In  the  above  description  distances  are  meas- 
ured along  axis  of  river,  and  for  heights  the  lake 
was  taken  at  104  and  the  sea  zero. 

The  Bends  of  the  San  Juan  River. 

There  are  on  the  river  a  number  of  bends,  by 
cutting  across  -which  the  canal  route  may  be  con- 
siderably shortened.  Eight  or  ten  of  these  are 
low  ground  and  show  no  evidence  of  rock;  two 
others,  however,  at  the  mouth  of  the  San  Carlos 
river  and  in  the  Agua  Muerta  are  of  high  rocky 
land  and  will  have  to  be  cut  through  or  skirted 
by  curves  of  the  minimum  radius. 

Machuca  Dam  Site. 

An  investigation  was  made  at  Machuca  for  a 
dam  site.  On  the  north  bank  a  crest  at  an  ele- 
vation above  110  was  closed  for  two  and  a  half 
miles  and  a  reconnaissance  made  until  the  Ma- 
chuca creek  itself  was  above  110.  On  the  south 
bank  a  crest  was  closed  for  one  and  a  half  miles, 
when  the  general  characteristics  of  the  country 
indicated  that  there  was  no  possibility  of  any 
embankment  being  needed,  the  ridge  itself  being 
well  defined,  and  as  far  as  we  went  nothing  was 
found  below  an  elevation  of  160  on  the  crest. 
Topography  was  also  taken  for  a  lock  site. 

The  Tributabies  of  the  San  Juan. 

The  San  Juan  has  a  number  of  small  tribu- 
taries and  but  few  large  ones,  the  most  import- 


ant being  the  Frio,  Poco  Sol,  San  Carlos  and 
Sarapiqui  rivers,  all  of  which  rise  in  the  Costa 
Rica  mountains  on  the  south  side  of  the  valley. 
From  the  lake  to  Castillo,  among  the  tributaries 
to  the  north,  are  the  Melchora,  Palo  de  Arco, 
Negro,  Savalos  and  Santa  Cruz  rivers.  From 
the  south  are  the  Frio,  Medio  Queso,  Poco  Sol, 
and  Poquito  Sol  rivers.  These,  as  far  as  I  have 
observed,  all  seem  to  flow  in  a  northwesterly  and 
southwesterly  direction  until  they  join  the  main 
river.  The  Rio  Frio  in  times  of  high  water  is 
also  a  tributary  of  the  lake. 

Among  the  tributaries  from  Castillo  to  the 
sea,  Bartola,  Machuca,  N.  Cruz,  Maclyida, 
Danta  and  San  Francisco  are  from  the  north, 
and  the  Infemito,  S.  Cruz,  San  Carlos,  Cerano, 
Tamborcito,  Copalchi  and  Sarapiqui  rivers  are 
from  the  south.  These  all  seem  to  rise  normal 
to  tlie  San  Juan. 

On  entering  the  delta  plain  the  distributaries 
of  the  San  Juan  are  the  San  Juanillo,  San  Juan 
(proper),  Colorado,  Taura,  Parada  and  Cafio 
Bravo,  the  rivers  discharging  into  the  sea  at 
Harbor  Head,  Colorado  bar.  Grey  town  and  the 
mouth  of  the  Taura.  At  times  the  openings  at 
Greytown  and  the  mouth  of  the  Taura  are  closed. 

The  tributaries  of  the  whole  river  are  seldom, 
if  ever,  muddy  or  carrying  sediment.  In  fact 
the  San  Juan  and  its  tributaries  may  be  said  to 
be  remarkably  free  from  sediment  in  the  ordi- 
nary acceptance  of  the  term.  The  San  Carlos, 
however,  discharges  a  very  considerable  quantity 
of  volcanic  sand,  as  does  also  the  Sarapiqui, 
though  to  a  lesser  degree.  The  rest  of  the 
rivers,  so  far  as  observed,  are  free  from  this  sand. 

Fluctuation. — From  the  nature  of  the  upper 
San  Juan  from  the  lake  to  San  Carlos  river,  it 
is  of  slow  movement  as  to  rise  and  fall;  two- 
thirds  of  its  water  coming  from  the  lake,  which 
ser\'es  as  an  equalizing  basin. 


APPENDIX  v.— REPORT  OF  F.   L.   STUART.   ASSISTANT  ENGINEER 


367 


In  the  reach  above  the  Toro  the  greatest  dif- 
ference of  height  between  low  and  full  river 
corresponds  to  the  varying  height  of  the  lake, 
and  from  the  Toro  to  the  Agua  Muerta  it  has  a 
probable  fluctuation  of  eight  feet.  From  its 
constant  nature  this  part  of  the  river  can  be 
dealt  with  with  a  degree  of  confidence  not  usual. 

The  lower  portion  of  the  river  from  the  mouth 
of  the  San  Carlos  to  the  sea  presents  a  combina- 
tion of  conditions  quite  different.  Its  tribu- 
taries, at  times  of  exceptional  flood,  are  torren- 
tial and  have  a  combined  discharge  twice  as  large 
as  the  upper  San  Juan  for  a  few  hours.  The 
San  Carlos  at  times  backs  up  the  San  Juan  in 
the  Agua  Muerta  and  presents  an  exceptional 
case  of  a  tributary  depositing  sand  for  some  dis- 
tance upstream  against  the  current  of  the  main 
river.  There  is  a  probable  fluctuation  at 
periods  of  extreme  low  and  high  water  of  some 
15  or  20  feet.  From  conclusions  arrived  at 
from  various  sources,  I  estimate  there  may  be  a 
fluctuation  of  from  4  to  8  feet  in  24  hours  in 
this  portion  of  the  river. 

Winds. — The  northeast  trade  winds  predomi- 
nate in  the  San  Juan  vallev  but  do  not  reach  a 
velocity  sufficient  to  be  considered  in  any  way 
detrimental  in  the  canal  question. 

Rocks. — The  rocks  found  along  the  river  con- 
sist generally  of  dolorite,  or  diabase  having  a 
badly  decomposed  surface,  and  volcanic  breccia. 
Nearly  everywhere,  except  in  the  bottoms  of 
the  ravines,  the  rock  is  covered  with  a  heavy 
layer  of  clay. 

None  of  the  rock  which  we  have  seen  has  ap- 
peared suitable  for  cut  work.  Much  of  it,  how- 
ever, is  suitable  for  filling  in,  notably  at  Toro 
rapids,  Castillo,  Punta  Gorda,  Machuca,  Agua 
Muerta,  San  Francisco  and  Loma  Ultima  on  the 
Colorado  river  about  six  miles  from  the  sea. 
On  the  west  side  of  the  lake  there  is  a  species 


of  basalt  which  is  used  in  the  masonry  work  of 
the  country.  This,  however,  from  what  I  am  able 
to  learn,  cannot  be  easily  obtained  in  thickness 
of  over  a  foot. 

Timber. 

Trees  Suitable  for  Piles  in  the  Sea. — 
Pejebaya,  Makenga,  Cocoanut — the  old  trees 
of  these  varieties  may  be  found  scattering  in  the 
coastal  plain,  and  it  is  believed  that  they  will 
withstand  the  attacks  of  the  Toredo  Navalis  bet- 
ter than  any  other  untreated  indigenous  wood. 

Trees  Suitable  for  Exposure  to  Weather, 
Earth  or  Fresh  Water. — Palo  Cortez,  Guachi- 
pilin,  Roble-Montez,  Cocobole,  Granadillo, 
Guyacan,  Almendro,  Pine,  Madera  Negra  and 
Guapinole.  The  first  seven  are  very  hard  woods 
and  can  be  found  straight  up  to  25  feet.  The 
pine  grows  in  quantity  along  the  coast  from 
Pearl  lagoon  up  to  Honduras.  In  Pearl  lagoon 
there  are  at  present  saw  mills  with  capacity  of 
10,000  feet  B.  M.  per  day.  The  Madera  Negra 
grows  very  crooked,  but  is  the  best  wood  in  thfe 
coimtry  for  cross-ties. 

Wood  Used  in  Buildings. — Cedro,  Pochote, 
Nispero,  and  Laurel.  With  the  exception  of 
pine  the  before  mentioned  woods  do  not  grow 
in  groups,  and  in  the  forest  on  the  east*  side  can 
only  be  found  in  small  clusters  of  from  two  to 
ten.  As  most  of  these  woods  sink  in  rafting, 
and  on  account  of  the  expense  of  getting  such 
scattering  trees  to  a  mill,  I  am  of  the  opinion 
that  the  native  timber  cannot  be  depended  upon 
for  canal  construction,  and  that  such  timber  as  is 
necessary  can  be  imported  considerably  cheaper 
than  by  establishing  mills.  All  timber  not  im- 
ported which  is  used  along  the  river  or  in  the 
interior  is  sawed  by  hand,  there  being  no  mills 
around  Lake  Nicaragua. 

Present  Land  Values  and  Fertility. — 
There  is  no  attempt  at  the  cultivation  of  crops 


368 


NICARAGUA  CANAL  COMMISSION 


in  the  San  Juan  vallev.  There  are  two  ranches 
which  are  making  a  desultory  attempt  to  plant 
nibber  and  cocoa  trees.  The  cattle  are  few  and 
very  poor.  Banana  cultivation  is  prohibited  by 
a  lack  of  harbor  facilities. 

From  the  density  of  the  vegetation  the  land 
is  very  fertile.  This  fertility  being  the  great 
drawback  of  the  region  with  its  present  facilities, 
the  forest  vegetation  is  with  great  difficulty  sub- 
dued and  at  too  great  a  cost.  Considering  the 
location,  present  condition  of  river  and  seaport, 
the  climate  and  rainfall,  I  deem  this  valley  about 
as  valuable  as  our  western  deserts,  and  that  it 
will  take  as  much  energy  and  industry  to  develop 
it  as  it  has  to  transform  these  western  wastes 
with  which  we  are  familiar. 

Rainfall. — The  rainfall  at  Greytown  is 
about  250  inches  per  year,  while  sixty  miles 
north  or  south  of  Greytown  it  is  very  much  less. 
The  rainfall  also  diminishes  on  ascending  the 
river  to  the  lake  where  there  is  a  distinct  wet 
and  dry  season. 

The  excessive  rainfall  at  Greytown  may  be 
caused  by  the  moisture-laden  trade  winds  being 
disturbed  by  the  effects  of  the  Nicaraguan  de- 
pression on  their  currents,  thus  inducing  precipi- 
tation as  they  strike  the  coaat  at  Greytown, 
which  is  normal  to  the  \vind;  but  a  satisfactory 
cause  for  this  peculiarity  of  the  region  has  never 
been  given. 

Climate. — The  climate  on  the  San  Juan  river 
has  been  very  uniform,  rarely  very  hot  or  cold, 
and  I  would  conclude  from  the  fact  that  the 
eight  or  ten  officers  and  the  thirty  or  forty  labor- 
ers who  have  composed  our  camp  for  the  last 
seven  months  have  all  been  in  good  health  (with 
one  exception),  that  the  river  at  present  is  very 
healthful.  The  men,  ourselves  included,  have 
camped  in  tents  along  the  banks  of  the  river, 
have  been  exposed  to  the  constant  rains,  have 


had  no  water  to  drink  except  that  of  the  river, 
have  followed  the  dictates  of  their  tastes  in  eat- 
ing such  food  as  was  provided,  have  had  no  med- 
ical attention,  and  yet  have  been  perfectly  well. 

The  river  is  very  sparsely  settled,  but  of  the 
population  who  lead  temperate  lives  we  have 
seen  little  or  no  sickness.  That  this  general 
healthfulness  of  the  river  valley  will  continue 
under  the  construction  of  the  canal  is  unlikely, 
and  provision  will  have  to  be  made  for  handling 
the  sick. 

Labor. — The  labor  of  Nicaragua  is  adapted 
to  such  classes  of  work  as  machete  work,  clear- 
ing right  of  way,  or  packing  in  supplies  to  camps 
by  canoe  or  trail.  This  is  about  the  extent  to 
which  the  native  labor  may  be  depended  upon 
in  any  quantities.  The  great  drawbacks  in 
teaching  them  other  work  are  that  they  are  not 
accustomed  to  work  more  than  half  the  day,  are 
not  prompt,  have  known  little  but  martial  re- 
straint, and  are  restless  and  constantly  on  the 
move.  Not  knowing  the  incentive  of  hunger, 
and  having  no  ambition,  they  cannot  be  de- 
pended upon  for  the  mainstay  of  the  construc- 
tion of  the  canal.  Such  labor  will  have  to  be 
imported  at  the  beginning  of  work  and  such 
forces  added  to,  year  by  year,  until  completion. 

Imported  labor  deteriorates  rapidly.  My 
opinion  being  expressed  in  percentage  of  a  man's 
usefulness  in  the  United  States,  is,  for  the  first 
12  months,  75  per  cent.,  second  12  months,  50 
per  cent.,  and  by  that  time  he  has  assimilated  so 
much  of  the  habits  of  the  tropics  that  his  use- 
fulness in  some  branches  of  work  is  entirely 
gone. 

Political  Division. — From  the  sea  to  a  point 
three  miles  below  Castillo  the  San  Juan  river 
forms  the  boundary  line  between  Nicaragua  and 
Costa  Rica.  Circling  with  Castillo  as  a  center, 
and  with  a  three-mile  radius  the  boundary  line 


APPENDIX  v.— REPORT   OF  F.   L.   STUART,   ASSISTANT   ENGINEER 


369 


swings  to  the  south  of  the  river  and  keeping 
three  miles  distant  runs  parallel  to  the  river  and 
lake  to  the  Sapoa  river,  which  empties  into  the 
lake-  opposite  Madera.  From  the  Sapoa  river 
the  boundary  line  strikes  across  to  the  Pacific 
ocean  at  Salinas  bay. 

Deduction  as  to  Canal  Field. — From  the 
information  enumerated  in  this  report,  I  am  of 
the  opinion  that  the  use  of  the  San  Juan  from  a 
point  half  a  mile  above  the  mouth  of  the  San 
Carlos  river  to  the  junction  of  the  San  Juan 
and  Colorado  rivers  is  prohibited  for  canal  pur- 
poses, as  is  also  the  south  side  of  the  river  be- 
tween these  two  points.  This  leaves  the  upper 
San  Juan  and  the  north  bank  of  the  low^er  San 
Juan  as  the  field  for  a  canal,  and  one  which  does 
not  necessitate  the  solving  of  other  than  very 
simple  engineering  problems,  and  with  few,  if 
any,  unknown  conditions  to  be  guessed  at. 

Remarks. 

Value  of  Survey. — ^In  conclusion,  I  wish  to 
add  that  the  survey  of  the  river  (proper)  is  ample 
for  preliminary  lo<l;ations  of  a  canal.  Special 
studies  will  have  to  be  made  in  more  detail  of 
the  various  bends  and  dam  sites  as  is  usual  before 
final  location. 

The  soundings  of  the  river  appear  to  be  ample 
for  final  locations,  necessitating  only  the  ordi- 
nary cross  sectioning  before  construction  begins. 

Suggestions. — It  seems  to  me  pertinent  to 
make  the  following  suggestions  of  work  that  it 
might  be  advisable  to  do  prior  to  the  acceptance 
of  any  location  as  final,  and  pending  the  com- 
mencement of  such  detail  work  of  investigation 
as  properly  comes  under  the  head  of  constructive 
locations: 

The  development  of  the  110-foot  contour  in 
the  upper  reaches  of  the  river; 

Further  detail  topography  of  the  delta  plain; 

24 


Additional  sectional  borings  of  the  river  could 
with  advantage  be  taken  at  San  Carlos,  Mel- 
chora,  Savalos,  Castillo,  and  one  mile  above  Ma- 
chuca; 

A  more  extended  topographic  study  of  the  re- 
gion to  the  eastward  of  the  southern  portion  of 
the  lake;  or  it  might  also  be  well  to  make  a 
barometric  reconnaissance  for  forty  miles  north 
of  Castillo  for  the  purpose  of  ascertaining  defi- 
nitely that  the  increase  in  the  height  of  the  val- 
leys and  summits  to  the  northward  is  a  fact,  as  is 
pointed  out  by  all  deductions  on  the  subject,  a 
recorded  instrumental  proof  being  alone  lacking. 

As  there  seems  to  be  disagreement  of  the  va- 
rious determinations  of  the  latitude  and  longi- 
tude of  Greytown,  San  Carlos  and  Brito,  and  as 
there  is  a  telegraph  with  cable  connection  at 
these  points,  this  matter  could  and  should  be 
readily  settled. 

Methods  of  the  Survey. — The  general 
method  by  which  the  work  of  the  survey  was 
done  was  to  establish  a  camp  of  tents  and  native 
sheds  on  the  banks  of  the  river,  finish  the  work 
for  four  or  five  miles  on  either  side  of  the  camp 
and  then  move  to  the  next  camp  site  in  our  small 
canoes,  provisions  being  sent  once  a  month  from 
Greytown  on  the  river  steamers. 

The  Stadli  Line. — The  stations  on  this  were 
placed  at  an  average  distance  of  about  1200  feet 
apart.  Depending  on  the  nature  of  the  ground 
four  kinds  of  stations  were  used;  first,  the  ordi- 
nary hub,  where  the  ground  was  sufficiently 
firm;  second,  three  small  piles  for  the  tripod 
where  the  ground  was  unstable;  third,  a  large 
pile  to  which  the  trivet  was  nailed;  fourth,  the 
prepared  stump  of  a  tree  to  which  the  trivet  was 
also  nailed;  in  the  two  latter  cases  the  observer 
stood  in  a  boat,  as  the  station  was  usuallv  in 
from  two  to  six  feet  of  water. 

In  observing,  the  back  and  front  transit  rods 


370 


NICARAGUA  CANAL  COMMISSION 


were  read  for  azimuth,  and  then  the  stadia  rods 
for  thread  readings  as  nearly  simultaneously  as 
possible,  all  three  threads  being  read  and  the  ver- 
tical angle  noted,  if  any.  The  forward  and 
back  readings  between  stations  were  averaged 
for  the  true  distance  between  any  two  stations. 

The  Levei^. — After  reading  for  distance  and 
azimuth  the  instrument  was  adjusted  for  the 
level  readings  and  the  front  and  back  rods  read 
as  nearly  simultaneously  as  possible,  the  two  up- 
per hairs  being  read  and  this  reading  compared 
with  the  stadia  reading.  The  elevation  of  the 
surface  of  the  water  was  also  taken  at  each  sta- 
tion as  an  additional  check.  The  elevation  of 
the  instrument  above  the  top  of  all  the  hubs 
occupied  was  taken.  This  gave  two  determina- 
tions of  the  elevation  of  each  station,  the  notes 
being  so  divided  as  to  keep  two  sets  of  levels, 
and  tlie  average  was  used  as  the  true  elevation. 

The  shore  line  was  taken  with  the  stadia,  the 
up  and  down  river  boats  approaching  each  other 
until  they  met,  points  being  taken  about  every 
300  feet. 

Topography. — Topography  ^vas  taken  by  cut- 
ting trails  into  the  woods  from  600  to  1000  feet 
in  length  and  about  1000  feet  apart,  on  both 
banks,  compass,  chain  and  hand-level  being 
used.  The  taking  of  the  topography  was  par- 
ticularly difficult,  owing  to  the  denseness  of  the 
vegetation. 

Sounding. — Sounding  sheets  were  prepared 
from  the  stadia  notes  and  on  them  the  sounding 
lines  laid  out  540  feet  apart,  as  being  a  multiple 
of  27.  In  determining  the  position  of  the 
sounding  lines  the  center  of  the  river  was  gen- 
erally used  as  an  axis  and  radii  of  3000  feet  or 
more  used  when  curves  were  necessary. 

In  the  field  flags  were  placed  on  the  sounding 
lines  as  located  on  the  sheets,  and  then  these 
lines  sounded,  one  observer  being  in  the  boat  to 


take  straddling  angles,  while  a  laborer  occupied 
the  opposing  flag  and  kept  the  boat  on  line,  the 
lead  being  thrown  every  20  seconds.  From 
Machuca  to  the  Rio  San  Francisco  a  center  line 
was  also  run,  two  observers  being  in  the  boat. 

The  atmospheric  conditions  are  excellent  and 
for  the  seven  months  that  we  were  in  the  field 
we  worked  in  all  conditions  of  weather,  losing 
but  one  entire  day  on  account  of  a  heavy  down- 
pour of  12  hours.  While  working  in  the  almost 
incessant  rains  of  this  region  our  instruments 
Avere  kept  under  large  umbrellas  and  only  a 
heavy  downpour  obscuring  sight  delayed  the 
work. 

Members  of  Party. — The  party  on  the  sur- 
vey of  the  San  Juan  was  composed  of  the  fol- 
lowing members:  Francis  Lee  Stuart,  chief  of 
party;  S.  S.  Evans  and  Thaddeus  Merriman,  ob- 
servers; C.  H.  Stockton,  topographer;  C.  L. 
Hammond,  draughtsman;  and  Messrs.  Bern- 
stein, Torrington  and  Williams,  rodmen;  and 
from  20  to  40  native  laborers. 

The  checks  that  we  have  been  able  to  obtain 
on  our  work  were  of  such  a  creditable  nature 
that  I  deem  them  worthy  of  mention. 

On  a  line  of  levels,  S.  S.  Evans  observing,  the 
stations  being  from  1000  to  1500  feet  apart, 
and  the  length  of  line  69  miles,  the  Precise 
Level  party  afterwards  checked  our  work  within 
1/10  foot  for  56  miles,  and  within  3/10  foot  in 
69  miles. 

I  append  herewith  a  description  of  the  method 
of  leveling  which  we  used  on  our  survey,  pre- 
pared by  S.  S.  Evans,  assistant  engineer,  at  my 
request. 

In  our  stadia  work,  Thaddeus  Merriman  ob- 
serving, on  a  circle  of  20  miles,  with  stations 
from  1500  to  2000  feet  apart,  the  geodetic  posi- 
tions checked  within  80  feet,  and  the  levels  on 
the  same  line  by  less  than  1/10  foot 


APPENDIX  v.— REPORT   OF   F.   L.   STUART,   ASSISTANT   ENGINEER 


371 


I  wish  to  express  my  appreciation  of  the  ser- 
vices of  my  assistants  which  were  well  and  cheer- 
fully performed. 

LAKE  NICAEAGUA. 

The  survey  of  the  San  Juan  was  finished 
September  1,  1898,  and  proceeding  to  San  Car- 
los, with  a  newly  organized  party,  we  made  a 
triangulation  and  hydrographic  survey  of  Lake 
Nicaragua. 

Scope  of  Survey. — The  entire  lake  has  been 
surveyed  and  sounded  out. 

The  zero  of  the  survey  of  the  San  Jiian  river 
from  San  Carlos  to  the  sea  has  been  connected 
with  the  zero  of  the  survey  of  west  side  from 
the  lake  to  the  Pacific,  thus  making  a  continuous 
survey  from  ocean  to  ocean. 

The  initial  point  of  lake  survey  being  station 
A  of  hydrographic  base  line  at  San  Carlos,  a 
skeleton  system  of  triangulation  was  developed 
and  then  the  shore  line  and  islands  and  soundings 
filled  in.  A  second  base  line  was  measured  at 
San  Jorge  for  the  purpose  of  a  check  on  the  ac- 
curacy of  the  work. 

Soundings  were  taken  in  a  systematic  way 
over  sailing  routes  of  canal  and  also  over  the 
entire  lake.  Diligent  search  was  made  for 
sunken  peaks  or  bars. 

Location. — Lake  Nicaragua  is  an  oblong 
body  of  fresh  water  101.2  miles  long  by  45.1 
miles  wide  as  extreme  dimensions,  with  an  area 
of  2975  square  miles.  Its  greatest  length  is  in 
a  northwesterly  or  southeasterly  direction,  it 
being  a  part  of  the  long  narrow  basin  which  runs 
northwesterly  across  Nicaragua  from  Greytown 
to  the  headwaters  of  the  Sinecapa  river. 

It  belongs  to  the  Atlantic  watershed  at  pres- 
ent, the  line  of  water  partings  of  the  two  oceans 
forming  the  southwesterly  boundary  of  the  lake 
basin. 


This  parting  line  in  the  stretch  of  country 
separating  the  lake  from  the  Pacific  is  but  five 
miles  from  the  lake,  the  lake  shore  itself  ap- 
proaching within  twelve  miles  of  the  ocean. 

The  discharge  of  the  lake  has  its  outlet  at  San 
Carlos  in  the  southeast  end,  and  flows  through 
the  San  Juan  river  a  distance  of  121.7  miles 
into  the  Caribbean  sea.  The  lake  surface  was 
from  104  to  106  feet  above  Caribbean  mean  sea 
level  during  this  survey. 

The  highest  point  of  the  canal  route  through 
the  Continental  Divide  is  but  50  feet  higher 
than  the  surface  of  the  lake.  This  point  is  in 
the  lowest  depression  in  the  dividing  chain  of 
hills  between  the  oceans  that  has  been  found  on 
the  continent. 

Bottom. — The  bottom  of  the  lake  is  covered 
with  silt  and  has  for  the  most  part  a  gentle  slope 
towards  Ometepe  and  Madera. 

The  greatest  depth  found  was  200  feet,  about 
three-quarters  of  a  mile  southeast  of  Madera. 

There  is  a  well-defined  depression  that  has 
been  only  partially  filled  up  in  the  general  level- 
ing that  has  taken  place.  This  depression  or 
channel  is  found  at  two  points  and  is  parallel  to 
the  axis  of  the  lake,  one  portion  north  of  the 
Solentiname  groups  of  islands,  and  the  other  and 
deeper  portion  near  Madera.  This  is  an  unmis- 
takable evidence  of  a  drowned  topography. 

A  sand  bar  was  found  on  a  line  between  Ome- 
tepe and  Punta  Palmar,  which  extends  a  couple 
of  miles  into  the  lake. 

With  these  two  exceptions  the  bottom  of  the 
lake  was  found  to  have  been  quite  uniformly 
leveled  by  the  silt 

In  general,  the  30-foot  curve  is  about  half  a 
mile  from  the  shore  on  the  south  and  west  sides, 
from  one  to  two  miles  on  the  north  side  and  from 
ten  to  fifteen  miles  in  the  southeast  end  near  its 
outlet.     Of  the  2975  square  miles  of  the  lake's 


372 


NICARAGUA   CANAL  COMMISSION 


area,  2300  square  miles  has  a  depth  of  over  30 
feet 

Watershed. — The  watershed  of  12,500 
square  miles,  including  the  lake  itself,  may  be 
said  to  be  elliptical,  its  width  being  70  miles  and 
length  250  miles,  its  greatest  length  bemg  par- 
allel to  the  axis  of  the  lake. 

The  boundary  lines  of  this  watershed  can  be 
described  as,  on  the  south  and  west  the  Costa 
Rican  and  Xicaraguan  moimtains,  lying  in  that 
narrow  stretch  of  country  which  separates  the 
lake  from  the  Pacific;  on  the  north  and.  east  by 
dissected  plateaus  under  the  general  name  of 
Chontales  hills. 

This  shed  is  subject  to  a  wet  and  dry  season 
of  about  equal  duration.  The  rainfall  varies, 
however,  in  different  parts  of  the  watershed,  be- 
ing generally  greater  in  the  San  Carlos  end  than 
in  the  Managua.  This  is  due  to  the  northeast 
trade  winds  arriving  laden  with  moisture  col- 
lected in  their  passage  over  the  ocean.  This 
moisture  begins  to  be  precipitated  on  reaching 
the  east  coast  of  Nicaragua  and  continues,  though 
constantly  diminishing,  to  San  Carlos,  thus 
causing  a  less  marked  wet  and  dry  season  there 
than  on  any  other  portion  of  the  w^atershed. 

The  superficial  strata  of  the  basin  is  perme- 
able and  covered  with  heavy  turf  and  vegeta- 
tion, and  consequently  the  amount  of  detritus 
brought  down  into  the  lake  is  small  in  com- 
parison with  similar  basins  in  the  temperate  zone 
which  have  a  smaller  rainfall  that  is  more  uni- 
formly divided  during  the  year. 

Fluctuations. — The  area  and  capacity  of  the 
lake  is  so  large  in  proportion  to  its  watershed  that 
it  necessarily  varies  but  slowly  from  any  pos- 
sible set  of  the  physical  conditions  by  which  it 
is  governed.  Its  fluctuation  from  any  possible 
combinations  of  conditions  in  24  hours  may  be 
from  6  to  12  inches. 


The  fluctuation  from  any  consecutive  wet  and 
dry-  season  is  from  3  to  8  feet. 

The  extreme  fluctuation  reported  from  any 
series  of  wet  years  for  highest  water,  and  any 
series  of  dry  years  for  lowest  water,  is  believed 
to  be  13  or  15  feet. 

Prinxipal  Tributaries. — On  the  north  side 
the  Malacatolla,  Apala,  Ormiguerro,  MoUales, 
Nancital,  Catarina,  Ollate,  Tepenaguasape  and 
Camastra  rivers; 

On  the  southeast,  the  Frio,  Poponochal,  Papa- 
nuro  and  Zapote  rivers; 

On  the  south  the  San  Bartolo,  Pisote,  Sapoa, 
and  Ochomogo  rivers,  and  on  the  northwest  the 
Tipitapa  river  which  connects  Lake  Nicaragua 
with  Lake  Managua. 

During  the  wet  season  the  rivers  have  consid- 
erable currents  while  in  the  drj^  season  nearly 
all  become  stagnant^  and  their  mouths  fill  up 
with  a  long  grass,  which,  breaking  loose  at  the 
beginning  of  the  wet  season,  floats  around  the 
lake,  finally  disappearing  down  the  San  Juan 
river. 

But  two  or  three  of  the  tributaries  have  any 
flow  in  the  dry  season,  the  Rio  Frio  in  the  south- 
east end,  and  the  Tipitapa  in  the  northwest  end 
have  the  most  noticeable  flow  and  even  these  are 
said  to  be  stagnant  at  times. 

From  its  tributaries  and  basins  during  the 
six  months  of  wet  season,  the  lake  receives 
enough  water  in  excess  of  evaporation  and  dis- 
charge to  give  it  a  storage  capacity  to  withstand 
the  action  of  evaporation  and  discharge  during 
the  dry  season  within  limits  of  3  to  8  feet 

Islands. — The  principal  islands  in  the  lake 
are  the  island  of  Ometepe  and  Madera,  con- 
taining 107  square  miles,  formed  by  two  extinct 
volcanoes;  the  island  of  Zapatera,  containing  21 
square  miles,  and  the  Solentiname  group  of 
islands,   containing   14^   square  miles.     There 


APPENDIX  v.— REPORT   OF  F.   L.   STUART,   ASSISTANT   ENGINEER 


37S 


are  also  quite  a  number  of  small  islands  in  the 
lake,  but  with  the  exception  of  Isla  Sonate  all 
are  within  a  few  miles  of  shore.  These  islands 
are  of  varying  heights;  from  an  elevation  of 
5110  feet^  which  is  the  height  of  Ometepe,  to 
20  feet  above  the  lake  at  Sonatito.  Most  of 
these  islands  appear  in  the  lake  without  any  fixed 
relation  to  the  topography  of  the  shore. 

A  diligent  search  by  us,  extending  over  several 
months,  has  not  developed  any  suaken  peaks. 

Shore. — The  shore  line  mav  be  divided  into 
four  well-marked  divisions,  showing  the  influ- 
ence of  the  trade  and  west  winds. 

First,  from  Punta  Boquete  to  Las  Haciendas 
the  shore  is  almost  entirely  a  swamp,  having  a 
mat  of  long  grass  back  of  which  the  tree  line  is 
well  marked.  This  is  seldom  a  lee  shore.  The 
hills  back  of  the  swamp  or  marsh  rise  abruptly 
and  partake  of  the  general  topography  of  that 
section  of  the  San  Juan  valley  between  the 
Toro  rapids  and  San  Carlos.  There  is  but 
one  town  (San  Carlos),  which  is  situated  on  a 
hill.  In  all,  some  ten  houses  in  this  section 
would  be  damaged  by  an  elevation  of  115  feet 
for  surface  of  lake.  The  marsh  land  is  at  times 
used  for  pasturage,  but  to  no  considerable 
extent. 

Second,  from  Las  Haciendas  to  the  Rio  Tipi- 
tapa  is  a  lee  shore  for  ten  months  out  of  the  year, 
which  has  a  sandy  beach  with  occasional  rocky 
spurs  east  of  San  Jorge.  The  settlements  on 
this  shore  are  Las  Haciendas,  15  houses,  situ- 
ated on  a  sandy  bar  with  an  elevation  of  112 
feet;  Sabalos  also  on  a  sandy  tract  with  an  eleva- 
tion of  117  feet;  and  Port  of  Granada,  with  five 
buildings,  below  115  feet.  There  are  also  some 
isolated  houses  on  this  section  which  are  about 
115  feet 

Third,  from  Rio  Tipitapa  to  San  Ubaldo  is 
xQvy  seldom  lee  shore  and  is  mostly  a  swampy 


shore  with  grass;  the  only  firm  ground  of  any 
magnitude  close  to  the  shore  is  in  the  vicinity 
of  Pelona  and  Congrejo.  There  are  probably 
some  five  or  six  farms  at  an  elevation  of  110  feet 
in  this  section. 

Fourth,  from  San  Ubaldo  to  Punta  Boquete 
is  a  lee  shore  for  two  months  of  the  year.  The 
shore  is  firm,  mostly  rock,  except  the  sandy 
beach  at  San  Ubaldo,  Morito  and  San  Miguelito. 
The  two  latter  are  small  villages  on  hillsides  of 
gradual  slope.  This  shore  is  woo<:led,  but  not 
heavily,  and  hills  rise  frequently  from  the  water's 
edge.  Some  10  houses  are  at  an  elevation  of 
112  feet  in  this  section. 

The  island  of  "  Ometepe  and  Madera  "  has 
firm  shores  and  there  may  be  some  half  dozen 
houses  at  an  elevation  of  112  feet  on  the  islands. 

The  other  islands  of  the  lake  have  usually 
rocky  shores  and*  there  are  not  more  than  six 
houses  at  an  elevation  of  less  than  112  feet. 

It  may  be  well  to  add  that  the  term  house  in 
this  respect  applies  to  a  building  of  from  one 
to  two  rooms,  made  without  the  use  of  any  man- 
ufactured articles  such  as  match  boards  or  tiles, 
and  without  a  floor,  except  earth;  usually  made 
in  Nicaragua  out  of  canes,  and  with  a  thatch 
roof,  and  of  little  value. 

Winds. — Winds  on  the  lake  vary  with  the 
wet  and  dry  seasons  but  the  northeast  winds 
predominate. 

From  November  or  December  to  April  or 
June  is  the  drv  season  and  the  winds  blow  from 
the  northeast  to  east.  The  rest  of  the  year  is 
called  the  wet  season  and  the  winds  are  variable 
at  times.  They  blow  occasionally  seven  or  eight 
days  from  the  west,  when  the  northeast  winds 
return.  During  July,  August,  and  September 
there  are  frequent  short  squalls. 

There  arc  seldom,  if  ever,  heavy  storms  on 
the  lake,  though  strong  squalls  develop  at  times. 


374 


NICARAGUA  CANAL  COMMISSION 


The  lake  is  well  protected  from  northers  by 
the  range  of  high  moimtains  to  the  north. 

The  trade  winds  crossing  the  lake  are  strong 
and  steady  and  similar  in  character  to  those  met 
in  the  Caribbean  sea  off  the  Greytown  coast, 
and,  like  Greytown,  the  lake  is  outside  of  the 
range  of  the  cyclonic  disturbances  of  the  West 
Indies. 

Waves. — The  waves  from  the  trade  winds  are 
short  and  choppy  and,  while  it  is  believed  that 
they  do  not  exceed  8  feet  from  crest  to  trough 
on  the  soutliwest  sliore  where  they  are  the 
heaviest,  they  should  not  be  disregarded.  A 
small  breakwater  at  the  entrance  to  the  canal 
at  Las  Lajas  being  advisable.  The  San  Carlos 
end  is  protected  by  hills  and  will  not  need  such 
a  provision. 

Anchorages. — To  the  west  side  of  Madera, 
San  Franciscp  bay,  carrying  40  feet  of  water, 
offers  a  particularly  good  anchorage  for  ships. 
It  is  opposite  the  entrance  to  the  west  side  canal. 
The  bay  is  2i  miles  by  5  miles,  and  the  deep 
water  approaches  close  to  the  shore. 

At  Moyogalpa  on  the  WTst  side  of  Ometepe 
is  a  shallow  indentation,  with  a  sandy  beach  free 
frcim  rocks  offering  a  safe  anchorage  for  ships. 

Sailing  Route  of  Canal. — The  distance 
along  sailing  route  of  canal  through  the  lake 
from  San  Carlos  to  the  lake  entrance  of  the  west 
side  canal  is  71.2  miles,  of  which  13.1  miles  at 
the  east  end  will  have  to  be  dredged,  the  rest 
of  the  distance  carrv-ing  ample  water  for  the 
heaviest  ships. 

Land  Values. — From  observations  I  am  of 
the  opinion  that  but  small  damage  to  property 
around  the  lake  will  be  caused  bv  the  surface  of 
the  water  reaching  at  times  an  elevation  of  112 
feet.  Land  along  the  shore  at  an  elevation 
between  110  and  120  is  used  principally  for 
cattle     pasturage.      There    are    no    cultivated 


areas,  but  scattering  here  and  there  may  be 
found  cursory  and  unmethodical  attempts  to 
raise  the  necessary  food  for  the  immediate 
families. 

Climate. — The  climate  on  the  lake  is  different 
from  that  of  the  San  Juan  river  and  under  pres- 
ent conditions  can  be  said  to  be  healthful  except 
during  the  months  of  change  from  the  wet  to 
the  dry  seasons. 

Labor. — More  extended  observation  on  the 
labor  question  in  Nicaragua  but  confirms  my 
previous  impressions,  that  any  work  of  magni- 
tude which  is  to  be  pushed  will  have  to  rely  on 
imported  labor  and  will  cost  more  than  similar 
work  in  the  United  States. 

Method  of  Survey. — A  skeleton  triangula- 
tion  was  developed  in  which  all  stations  were 
occupied,  except  Ometepe,  in  which  case  the 
angles  were  deduced.  Natural  signals  were 
cut  in  from  the  stations.  The  shore  line  was 
located  by  actual  occupation  of  shore  points  and 
also  cut  in  from  inshore  sounding  lines.  Sound- 
ings were  taken  from  the  Nicaraguan  Govern- 
ment steamer  "  El  93,''  which  was  placed  at  the 
disposal  of  the  Commission  for  these  studies. 
Sounding  platform  w^as  four  feet  above  water 
and  the  lead  used  12  pounds.  A  sounding  was 
taken  every  minute  or  half  minute,  and  in  water 
over  7  fathoms,  speed  was  slackened  every  five 
minutes  for  check  soundings.  Sounding  posi- 
tions were  taken  every  five  or  ten  minutes  by 
sextant  observers  in  the  steamer. 

Members  of  Party. — The  party  consisted  of 
Francis  Lee  Stuart,  chief  of  party;  Thaddeus 
Merriman,  C.  II.  Stockton,  C.  L.  Hammond, 
George  J.  Smart,  R  .N.  Begien,  J.  C.  Taylor, 
R.  ('.  Wheeler,  Sherwood  Wilson,  and  Lester 
Bernstein,  and  from  40  to  70  native  laborers. 

We  commenced  the  survey  September  1,  and 
that  we  were  able  to  finish  November  21,  1898, 


APPENDIX  v.— REPORT   OF  F.   L.   STUART,   ASSISTANT   ENGINEER 


375 


was  due  to  the  efficiency  and  zeal  of  my  assist- 
ants. 

After  completion  of  the  lake  survey  the 
steamer  "  El  93 "  was  returned  to  the  Xica- 
ragiian  Government  and  I  disbanded  my  party, 
leaving  three  members  for  further  duty  in  Nica- 
ragua and  directing  the  others  to  report  in 
Washington. 

WOKK  IN  THE  UNITED  STATES. 

Upon  arrival  in  the  States  the  following  maps 
were  made  of  the  survey  of  Lake  Nicaragua: 
Smooth  map  of  Lake  Nicaragua  to  a  scale  of 
1 0  o'o  0  0  showing  triangulation  stations,  signals, 
sounding  positions,  soundings  and  shore  topog- 
raphy. Record  map  for  reconstruction,  8 
miles  to  the  inch,  showing  triangulation  stations, 
signals  and  cuts,  with  angles,  distances,  etc. 
Map  of  Lake  Nicaragua,  scale  rjinjirTr  for  pub- 
lication. 

I  was  also  assigned  to  make  estimates  and 
studies  of  lock  and  dam  systems  and  possible 
canal  variants  on  the  eastern  division,  and  ^Ir. 
Thaddeus  Merriman,  R.  N.  Begieu  and  R.  C. 
Wheeler  reported  to  me  as  assistants. 

Summit  Level. 

In  considering  any  question  relative  to  the 
summit  level  of  the  canal  such  as  width,  depth, 
slope  of  canal  section  or  dams  and  controlling 
works,  the  subject  of  control  of  the  lake  is  most 
important,  and  should  be  studied  first  under  cer- 
tain assumptions  and  a  decision  made. 

The  limit  of  range  of  fluctuation  of  the  lake 
to  be  provided  for  has  been  fixed  by  the  Commis- 
sion at  6  feet  or  from  a  surface  elevation  of  104 
to  110  feet. 

It  lias  been  assumed  that  the  current  in  the 
basin  from  the  lake  to  the  San  Carlos  river  must 


not  be  so  great  as  to  cause  erosion  of  banks,  thus 
necessitating  constant  cleaning  out  of  channel. 

Storage  Capacity. 

Briefly  the  conditions  which  affect  the  storage 
capacity  of  the  lake  during  the  year  of  minimum 
inflow  and  maximum  evaporation,  are: 

During  a  dry  season  the  evaporation  may  ex- 
ceed the  inflow  by  6  inches  per  month. 

The  maximum  evaporation  for  a  dry  season 

mav  be  60  inches. 

t.' 

The  minimum  inflow  mav  be  36  inches,  thus 
lea\nng  the  lake  24  inches  lower  than  at  the  be- 
ginning of  the  cycle. 

Considering  that  the  following  dry  season  may 
give  an  additional  fall  of  23  inches  and  that  the 
operating  of  the  locks  and  electric  plants  may 
cause  a  drop  of  4i  more  in  18  months,  we 
have  51i  inches  as  a  necessary  range  for  storage 
capacitv  should  the  lake  not  receive  anV  inflow 
except  as  at  present  If,  however,  the  water 
from  the  San  Juan  basin  be  impounded  during 
this  period  it  is  believed  that  the  51^  inches 
would  be  reduced  to  42  inches. 

With  its  present  inflow  the  lake  may  be  gov- 
erned in  a  vcar  of  maximum  inflow  and  mini- 
mum  evaporation  with  constant  discharges  for 
164  davs  as  follows: 

Within  limits  of  5-ft..  rise  by  a  discharge  of 
33,300  cubic  feet  per  second. 

Within  limits  of  4-ft.  rise  by  a  discharge  of 
39,200  cubic  feet  per  second. 

Within  limits  of  3-ft.  rise  by  a  discharge  of 
45,100  cubic  feet  per  second. 

Within  limits  of  2-ft.  rise  by  a  discharge  (►f 
51,000  cubic  feet  per  second. 

Within  limits  of  1-ft.  rise  by  a  discharge  of 
56,000  cubic  feet  per  second. 

Within  limits  of  0-ft.  rise  by  a  discharge  of 
62,500  cubic  feet  per  second. 


376 


NICARAGUA  CANAL  COMMISSION 


However,  the  question  is  not  the  control  of  the 
lake  alone  but  of  the  lake  and  so  much  of  the 
San  Juan  river  as  may  be  used  for  canal  pur- 
poses. 

The  time  covered  bv  obsen'ations  that'  have 
been  made  as  to  rainfall,  evaporation  and  run- 
off is  not  extensive  enough  to  warrant  any  as- 
sumption on  the  subject  being  other  than  good 
approximations.  In  view  of  this  fact  Mr. 
Davis's  statement  that  the  San  Juan  river  may 
receive  from  its  tributaries  between  the  lake  and 
the  San  Carlos  river,  50,000  cubic  feet  per  sec- 
ond, coupled  with  the  knowledge  that  the  rain- 
fall in  the  San  Juan  vallev  is  manv  times  heavier 
than  on  the  lake,  must  be  interpreted.  The  ex- 
treme assimiption  that  can  be  made  is  that  the 
50,000  cubic  feet  or  a  large  portion  of  it  is  dis- 
charged into  the  San  Juan  for  a  number  of  days 
or  weeks  during  the  wet  season. 

If  we  assume  that  the  50,000  cubic  feet  is 
delivered  to  the  river  in  a  uniform  way,  as  from 
zero  at  the  lake  and  being  augmented  propor- 
tionally to  the  distance  until  the  sum  of  the 
increments  is  equal  to  50,000  cubic  feet  at  Boca 
San  Carlos,  and  fix  a  limit  of  velocity  in  the 
channel  of  2  feet  per  second  on  account  of  the 
quality  of  material  and  the  sloping  sides  below 
the  surface,  the  canal  section  being  300  feet 
wide  on  bottom  with  side  slopes  2:1;  then  an  in- 
spection of  the  table  of  velocities  will  show  that 
with  one  dam  in  river,  the  east  spillway  can 
take  care  of  the  heaviest  rainfall  in  the  San  Juan 
A-alley  and  also,  if  desirable,  of  10,000  cubic  feet 
in  addition  from  the  lake,  without  causing  a 
velocity  greater  than  the  limit  except  at  the 
cut-off  at  Sombrero  de  Quero. 

The  requirements,  then,  for  governing  the 
summit  level,  which  seem  advisable  vmtil  further 
infonnation  is  at  hand,  are: 

That  there  be  a  spillway  on  the  west  side  and 


that  it  have  a  capacity  of  at  least  30,000  cubic 
feet  per  second. 

The  spillway  at  dam  on  east  side  should  have 
a  capacity  of  60,000  cubic  feet  per  second  or 
more. 

The  controlling  works  at  spillway  on  east  side 
shoiild  be  able  to  hold  the  water  at  114. 

The  lock  walls  should  be  built  to  116. 

If  we  had  no  information  of  value  about  the 
lake,  with  desirable  .limits  of  fluctuation  between 
104  and  110,  it  would  be  proper  at  all  times  to 
endeavor  to  keep  the  lake  as  near  107  as  possible. 
We  do  know,  however,  that  it  is  an  extremely 
unusual  year  which  does  not  have  a  very  marked 
wet  and  dry  season  in  this  region.  This  fact  is 
of  prime  importance  in  dealing  with  this  problem 
and  we  can  presume  on  it  to  the  extent  of  opera- 
ting the  east  and  west  side  plants  with  a  view  to 
having  the  elevation  of  the  lake  at  108  at  the  be- 
ginning of  any  dry  season  and  at  the  beginning 
of  the  wet  season  106^  or  as  much  lower  as  it 
may  be  from  losses  by  evaporation  and  operating 
alone. 

From  the  beginning  of  any  wet  season  untU 
the  lake  reaches  108  there  should  be  no  waste 
allowed,  but  upon  reaching  that  point  the  spill- 
ways should  be  used  to  their  full  capacity  until 
the  lake  ceases  to  rise. 

Though  it  is  feasible  it  cannot  be  considered 
desirable  to  have  as  much  of  a  current  on  the  east 
side  as  is  given  by  a  discharge  of  10,000  cubic 
feet  per  second  in  addition  to  the  50,000  cubic 
feet  received  by  the  San  Juan  from  its  tribu- 
taries. This  could  be  avoided  by  impounding 
and  drawing  out  of  the  lake  when  the  tributaries 
of  the  San  Juan  are  not  at  their  maximum  dis- 
charge, as  is  necessarj'  with  3  dams  in  river,  or 
in  a  much  more  advantageous  way  if  in  arrang- 
ing right  of  way  (or  concessions  from  the  Nica- 
raguan  Government)  an  exemption  from  claims 


APPENDIX  v.— REPORT   OF  F.   L.   STUART,  ASSISTANT  ENGINEER 


377 


for  damages  to  a  high  water  limit  of  an  elevation 
of  115  be  secured.  This  protection  from  claims 
of  damages,  I  believe  from  my  observation 
aroimd  the  lake,  could  be  secured  at  a  very  small 
cost  in  comparison  with  any  other  method  of  ge1> 
ting  such  a  satisfactory  range  of  control  and  is 
strongly  recommended  for  consideration. 

Velocities  in  River  and  Canal. 

A  study  of  the  velocities  to  be  expected  at 
certain  controlling  points  has  been  made  with 
discharges  varying  from  10,000  to  100,000  cubic 
feet  per  second. 

In  table  No.  1  on  page  383  are  shown  the 
velocities  dlie  to  various  quantities  of  water  pass- 
ing from  the  lake  and  being  augmented  so  that 
the  sum  of  the  increments  will  be  50,000  cubic 
feet  per  second  at  Boca  San  Carlos. 

An  inspection  of  this  table  shows  that  but 
10,000  cubic  feet  per  second  can  be  taken  from 
the  lake  without  causing  destructive  velocities 
in  the  river  section  of  the  canal.  There  is  one 
exception,  however,  at  the  cut-off  at  Sombrero 
de  Quero  where  the  current  in  the  canal  is  2.26 
per  second.  This,  however,  can  be  avoided  by 
widening  the  canal  300  feet  on  the  bottom 
through  this  cut-off. 

In  tables  No.  2  and  No.  3,  it  is  assumed  that 
no  water  is  allowed  to  waste  on  the  east  side  and 
we  see  that  but  30,000  cubic  feet  of  the  50,000 
cubic  feet  per  second  which  may  come  into  the 
San  Juan  valley  could  be  allowed  to  pass  into 
the  lake  without  exceeding  the  allowable  limit  of 
2  feet  per  second  the  remaining  20,000  cubic  feet 
would  have  to  pass  over  the  east  side  spillway. 

Table  Xo.  4  gives  the  velocities  in  the  canal 
and  river  section  at  Conchuda  cut-off  and  below 
for  various  quantities  of  water  and  with  the 
water  surface  at  different  elevations  correspond- 
ing to  the  possible  elevations  given  by  the  lock 


systems  in  this  section.  There  we  see  that  the 
velocity  is  not  excessive,  except  for  quantities 
of  over  30,000  cubic  feet  per  second  for  the 
lower  levels,  and  for  the  higher,  60,000  cubic 
feet  can  easily  be  passed. 

Submeboed  Abea. 

From  the  available  maps  a  computation  was 
made  of  the  area  submerged  by  the  pools  formed 
by  the  various  dams  contemplated  in  the  river  as 
follows: 

Surface  of  Water  110, 

Dam  at  Ochoa,  Maritime  route,  lake  to 

divide    95  sq.  ml. 

Dam  to  Boca  San  Carlos,  lake  to  Boca 

San  Carlos 48      " 

Dam  at  Lower  Machuca,  lake  to  Lower 

Machuca    40      " 

Lake  to  Upper  Machuca 35      " 

Lake  to  Castillo 29      " 

Surface  of  Water  91.6. 

Lower  Machuca  to  dam  at  Conchuda.  5  sq.  ml. 
Upper  Machuca  to  dam  at  Lower. ...   3 


u 


Surface  of  Water  7S.i. 

Conchuda  to  dam  at  Boca  San  Carlos .  li  sq.  ml. 
Lower  Machuca  to  Conchuda 3        " 

As  the  110-foot  contour  has  not  been  run  out 
this  estimate  of  areas  is  not  believed  to  be  closer 
than  limits  of  20  per  cent. 

CuBVE  Widening. 

As  to  which  side  of  a  curve  the  widening 
should  be  made  on  it  is  l)elieved  that  the  cheaper 
side  should  be  adopted.  When  a  ship  first  be- 
gins to  throw  its  helm  over  to  follow  a  curve  the 
pivotal  point  is  in  the  bow  and  the  stem  is  swung 
over  the  outside  of  the  curve,  as  the  ship  gets  on 
the  curve  the  pivotal  point  moves  back  until  it 


378 


NICARAGUA   CANAL  COMMISSION 


reaches  the  center  of  gravity  of  the  ship  where 
it  remains,  and  the  center  of  gravity,  which  is 
usually  near  the  center  of  length  of  the  ship, 
traces  the  curve.  As  vessels  in  the  canal  would 
follow  any  given  center  line  or  cim'c  only  as 
closely  as  the  different  pilots  will  force  them,  it 
may  not  be  considered  essential  to  have  the 
widening  on  any  particular  side.  However, 
given  a  cur\'e  whei*e  the  expense  of  widening  is 
the  same  on  either  side,  the  preference  should  be 
given  to  widening  on  the  outside  for  the  follow- 
ing reasons:  any  widening  on  the  outside  will 
tend  to  make  the  radius  of  the  effective  cross 
section  longer  and  the  curve  of  the  ship's  course 
flatter. 

Estimates. 

Basis  of  Estitnaif's. 

In  making  estimates  from  the  lake*  to  Boca 
San  Carlos  the  maps  of  the  surveys  made  by 
Lieut.  G.  C.  Hanus,  T".  S.  X.,  and  Assistant 
Engineer  Francis  Lee  Stuart,  were  used. 

The  geological  classification  was  made  by  Dr. 
C.  W.  Hayes  from  borings,  etc.,  made  under  his 
direction. 

Sections. — The  width  of  the  channel  used  in 
the  river  section  was  300  feet,  except  through 
cut-offs  having  solid  banks  on  l)oth  sides  for  a 
distance  of  more  than  1000  feet,  where  150  feet 
base  was  used. 

Side  Slopes. — The  side  slopes  used  were:  in 
sand  3  horizontal  to  1  vertical;  in  silt,  2  hori- 
zontal to  1  vertical;  in  clay,  1  horizontal  to  1 
vertical;  in  soft  rock,  ^  horizontal  to  1  vertical; 
in  hard  rock,  ^  horizontal  to  1  vertical. 

Lake. — In  the  lake  the  width  of  sections  was 
from  300  feet  at  entrance  of  river  to  GOO  feet 
at  30  foot  curve,  with  slopes  5  horizontal  to  1 
vertical  to  a  depth  of  6  feet,  then  3  horizontal  to 
1  vertical. 


Curve  Widening. — The  channel  was  widened 
in  river  section  as  follows: 

For  curves  of  3000'  rad.  increased  width,  100' 


a              a 

4000' 

4k 

%% 

a 

75' 

a              a 

5000' 

a 

k» 

a 

50' 

!Arore  than 

5000' 

a 

a 

a 

25' 

Revisions  of  Location. — A  revised  location 
was  made  and  at  doubtful  points  several  lines 
were  estimated  and  the  cheaper,  including  com- 
pensation for  any  shortening  of  distance,  was 
adopted.  The  line  was  thrown  over  where  pos- 
sible to  avoid  the  excavation  of  wet  rock. 

CuT-OFFS. — The  method  used  in  determining 
the  adoption  of  any  location  around  or  through 
the  bends  made  bv  the  river  was  as  follows: 

ft. 

It  was  assumed  that  an  extra  expenditure  of 
$250,000  could  be  made  per  mile  of  distance 
saved  by  cut-off  line.  In  calculating  the  cut-off 
line  when  over  1000  feet  long  a  base  of  150  feet 
was  used  as  against  a  base  of  300  feet  in  the 
river. 

The  cost  of  a  line  around  the  bend  was  com- 
pared with  the  line  through  or  across  it,  and  the 
cheaper  adopted.  The  principal  cut-offs  to  save 
distance  and  cost  were  from  Isle  Cano  to  Medio 
,Queso,  and  from  Palo  de  Arco  to  Isla  Grande, 
and  from  Soml^rero  de  Quero  to  Santa  Cruz. 
The  last  two  were  found  to  be  cheaper  than  the 
river  line,  and  adopted.  The  cut-off  from  Isla 
Cano  to  Medio  Queso  was  rejected.  It  may  be, 
however,  that  upon  making  a  more  careful  inves- 
tigation of  this  cut-off  it  may  be  found  advisable 
to  adopt  it  also. 

Lock  Systems. — The  grade  for  the  entrance 
of  the  canal  on  the  east  side  will  be  30  feet 
l)elow  mean  low  tide,  or  30.5  below  mean  sea 
level,  and  the  maximum  elevation  of  Lake  Xica- 
ragua  110,  making  the  tot^l  lift  110.5.  For  any 
svstem  of  locks  the  lift  in  each  lock  will  be  this 


APPENDIX  v.— REPORT   OF  F.   L.   STUART,   ASSISTANT   ENGINEER 


379 


amount  divided  l)v  the  number  of  locks  in  the 

•■' 

svstem. 

Variants. 

From  inspection  it  was  found  that  a  feasible 
lock  and  dam  system  for  the  canal  would  be  be- 
tween  a  5-lock  and  8-lock  system,  both  in- 
clusive, and  with  one,  two  or  three  dams  in  the 
river.  Accordingly  estimates  were  made  as  fol- 
lows: 

.•  .5A 


5 

Kjy^n.    c 

>J  OCCIJ 

LI,         J.       U,CIXJLI.      M.X 

2  dams 

,       A1.AC4X  IVVy  VI    < 

9 

...5M 

6 

1  dam 

u 

1 

,...6A 

6 

2  dams 

a 

...6X 

6 

3  dams 

u 

, ...6Z 

1  dam 

u 

a 

.  ...7A 

2  dams 

a 

. ...TU 

7 

3  dams 

u 

....7Y 

8 

1  dam 

(( 

a 

....8A 

8 

2  dams 

ii 

a 

. . . . 8B 

8 

3  dams 

{( 

a 

....8E 

The  prices  used  for  comparative  purposes 
were: 

All  earth  and  silt  excavation  .•  $       .37  per  cu.  yd 

Hard  and  soft  rock 93      "     " 

Dam  masonrv  concrete 8.30      "     " 

Clearing    75.00      "  acre. 

Clearing  and  grubbing 100.00      "     " 

Locks,  cost  depending  on  lift . 
Dam    construction    (other    than    masonry)    de- 
pending on  location. 

As  there  was  but  one  point  where  a  dam  must 
be  placed  in  any  scheme,  and  four  other  possible 
dam  sites,  to  make  the  study  exhaustive  other 
estimates  were  computed,  either  entire  or  to  such 
a  point  as  admitted  of  no  doubt  as  to  which  was 
the  most  desirable  location  for  dams  for  the  par- 
ticular variant  imder  discussion. 


Estimates  were  made  for  concrete  dams  and  of 
such  profiles  as  admitted  of  8  feet  of  water  flow- 
ing over  spillway.  Estimates  were  also  made 
for  concrete  locks  having  a  capacity  of  665  feet 
by  80  feet,  and  in  river  section  with  sufficient 
depth  to  admit  of  a  range  of  6  feet  between 
maximum  and  minimum  stages  of  water. 

Narrow  Canal  Estimate. — As  it  may  be 
advisable  to  build  a  canal  which  can  handle  the 
first  business  presented,  and  then  increase  the 
width  of  sections  and  make  other  betterments  as 
the  demand  arises,  an  estimate  has  been  made 
from  the  lake  to  Boca  San  Carlos  on  the  6-lock 
system  with  three  dams  in  the  river,  with  a  width 
of  base  150  feet  throughout,  passing  points 
2000  feet  long  every  5  miles  and  wooden  locks. 

Sketches. — The  accompanying  sketches  on 
page  385  symbolize  principal  variants  between 
the  30-foot  contour  in  lake  and  Boca  San  Carlos 
on  which  estimates  were  made.  The  position 
of  the  dams,  the  elevation  of  the  water  surfaces, 
the  length  of  line  and  the  comparative  costs  are 
shown.  In  these  estimates  the  cost  of  the  Boca 
San  Carlos  dam  is  included  but  the  lock  dropping 
from  the  level  of  this  dam  is  not. 

Value  of  Estimates. 

The  estimates  have  been  carefully  made  from 
the  available  data  and  mav  be  considered  as 
within  limits  of  approximate  estimates  for  simi- 
lar work  in  the  States. 

Description  of  Canal  Line. 

Sailing  Route  in  Lake. — The  sailing  route 
across  the  lake  would  be,  ^vith  the  surface  less 
than  110,  through  the  dredged  channel  passing 
north  of  Balsillas  islands,  a  distance  of  12.23 
miles,  then  curving  to  the  west  for  1.21  miles 
with  a  7500-foot  radius  to  deep  water,  then  tak- 


380 


NICARAGUA   CANAL  COMMISSION 


ing  a  bearing  of  south  80°  13'  west  (true)  for 
6.4  miles  (stat.)  then  curving  to  the  right  for 
.91  miles  (stat)  with  11,500-foot  radius,  it  takes 
a  bearing  of  K  76°  48'  AV.  (tnie)  for  52.63 
miles  (stat.)  to  entrance  of  west  side  canal,  the 
total  length  being  71.7  statute  miles. 

The  sailing  route  across  the  lake  with  the  sur- 
face of  the  lake  at  110  or  more,  would  be  through 
the  dredged  channel  passing  north  of  the  Balsil- 
las  islands  a  distance  of  12.22  miles  (stat.) 
thence  curving  to  the  west  for  .81  miles  (stat.) 
with  a  radius  of  7500  feet  to  deep  water,  then 
taking  a  bearing  of  N.  75°  45'  Ctnie)  for  57.98 
miles  (stat.)  to  the  entrance  of  the  west  side 
canal,  the  total  length  being  71.02  statute  miles. 

Canal  Line  in  Rivee. — From  the  lake  en- 
trance at  Fort  San  Carlos  the  canal  line  follows 
as  closely  as  possible  the  axis  of  the  San  Juan 
river  for  a  distance  of  13.1  miles  to  Palo  de 
Arco  where  it  cuts  across  the  bend  at  that  point. 
By  this  cut-off  the  length  of  the  canal  is  short- 
ened 1.3  miles.  From  here  the  line  again  fol- 
lows the  river  to  Sombrero  de  Quero,  a  distance 
of  11.2  miles  where  another  cut-off  is  made,  sav- 
ing 1.8  miles.  After  leaving  this  point  the  river 
is  closely  followed,  cutting  across  a  few  small 
points,  until  a  distance  of  40  miles  from  Fort 
San  Carlos  is  reached.  The  alignment  above 
this  point  is  constant  and  included  in  all 
schemes.  It  is  here  that  the  different  variants 
branch  off  and,  following  different  routes,  come 
together  again  at  Boca  San  Carlos. 

Variant  6A. — (The  6-lock  system  with  one 
dam  in  the  river.)  Continuing  from  the  con- 
stant, the  line  follows  the  axis  of  the  river  until 
the  bend  at  Conchuda  14.2  miles  below  is 
reached.  Here  the  cut-off  saves  a  distance  of 
.7  of  a  mile.  The  canal  then  follows  the  river 
to  Boca  San  Carlos  56.9  miles  from  Fort  San 
Carlos.     Here  is  situated  the  river  dam  holding 


the  lake  at  its  summit  level,  while  the  canal  line 
continuing  across  the  sharp  bend  at  this  point 
connects  with  the  low-level  lines  beyond. 

Variant  GZ. — (The  G-lock  system  with  3 
dams  in  the  river.)  Leaving  the  constant,  the 
line  follows  the  river  to  Lower  Machuca  a  dis- 
tance of  4.2  miles.  Here  is  situated  the  first 
of  the  river  dams  holding  the  lake  at  its  sum- 
mit level,  together  with  the  first  lock.  In 
this  lock  the  level  is  dropped  18.4  feet  to  86.6 
and  following  the  river  a  distance  of  10  miles 
to  Conchuda  a  second  dam  and  lock  are  reached ; 
the  canal  at  this  point  cutting  the  sharp  bend 
on  which  the  lock  is  situated.  The  level  is  here 
again  dropped  18.4  feet  to  68.2  and  continues  at 
this  elevation  to  Boca  San  Carlos  2.8  miles  be- 
low where  the  third  dam  and  lock  are  situated 
and  connecting  with  the  low-level  lines. 

ARouME^'Ts  FOR  A^'D  Agaixst  Variants. 

The  two  schemes  which  seem  to  offer  the  best 
features  in  the  river  section  are:  a  system  with 
but  one  dam  in  the  river,  and  the  six-lock  svs- 
tem  with  three  dams  in  the  river. 

Variant  6A. — (One  dam  in  the  river  situated 
near  the  mouth  of  the  San  Carlos  river.)  This 
gives  12  miles  more  of  basin  navigation,  thus 
permitting  a  higher  rate  of  speed  for  vessels 
than  any  other  variant,  and  is  equivalent  to 
shortening  the  canal  to  some  extent. 

The  dam  itself  would  be  the  only  one  on  the 
river  and  the  largest  and  most  important  single 
work  on  the  canal,  and  as  such  could  be  guarded 
against  a  public  enemy,  better  than  if  there  were 
several  dams,  each  of  vital  importance  to  the  op- 
eration of  the  canal. 

It  permits  of  more  water  being  taken  down 
the  San  Juan,  and  if  the  east  side  is  used  as  a 
spillway  could  control  the  summit  level  with  one 
foot  less  range  than  with  three  dams  giving  rise 


APPENDIX  v.— REPORT   OF  F.   L.   STUART.   ASSISTANT   ENGINEER 


381 


to  similar  velocities.     It  is  also  cheaper  than 
any  other  variant. 

The  argument  against  the  scheme  is  that  the 
single  dam  holds  the  basin  54  feet  above  the 
normal  river,  and  would,  if  destroved  bv  anv 
cause,  obliterate  a  very  large  amount  of  canal 
property.  The  disastrous  effect  of  such  a  hap- 
pening, should  it  occur,  can  only  be  siirmised. 
The  repairs  necessarj'  would  be  so  great  that  it 
would  not  be  a  matter  of  months  but  of  vears, 
before  the  canal  could  again  be  put  in  working 
order. 

Variant  6Z. — (The  six-lock  system  with 
throe  dams  in  the  river.)  The  chief  argument 
in  its  favor  is  that  it  reduces  the  head  of  water 
on  each  dam,  thus  removing  the  menace  of  the 
large  single  dam  at  Boca  San  Carlos. 

Should  any  dam  of  this  system  go  out  it  is 
probable  that  the  other  dams  would  not  be  af- 
fected and  the  river  would  soon  regain  its  old 
form.  As  against  this  factor  of  safety  is  the 
extra  cost  of  this  system  and  the  reduced  effi- 
ciency of  the  San  Juan  for  a  waste-weir. 

Respectfully  submitted, 

Fraxcis  Lee  Stuart, 
Assistant  Engineer. 

San  Juan  del  Norte,  Xicaraoua, 

Xovember  5,  1898. 

Mr.  Francis  Lee  Stuart, 

Asst.  Engr.,  X.  C.  C,  Granada,  Xic. 

Sir: — Answering  your  request  for  a  descrip- 
tion of  the  method  of  leveling  down  the  San 
Juan  river  eastward  from  Sian  Carlos,  I  beg  to 
hand  you  the  following.  The  instrument  used 
was  a  Brandis  transit  (No.  1759)  with  level 
bubble  attached  to  the  telescope.  It  was  set 
at  the  various  stations  of  a  zig-zag  line  passing 
from  one  side  of  the  river  to  the  other  and  at 
each  setting  the  azimuth  to  the  forward  station 


was  read,  then  the  stadia  distances  to  the  back 
and  forward  stations,  immediately  after  which 
readings  for  levels  were  taken  on  the  backward 
and  forward  stations.  The  rod  used  was  a  board 
3i  inches  wide  and  16  feet  long  graduated  to 
tenths  of  a  foot,  simply  and  plainly  marked. 
The  stations  were  sometimes  a  hub  driven  in  the 
ground,  sometimes  a  stump  of  a  tree  and  some- 
times a  pile  driven  in  the  mud  and  firmly  braced. 
Below  Savalos  the  stations  were  nearlv  all  hubs 
but  above  that  point  they  were  nearly  all  stumps 
or  piles.  The  instrument  was  set  over  the  latter 
by  nailing  the  board  to  which  it  is  attached 
while  in  the  box  to  the  top  of  the  stump  or  pile 
and  screwing  it  to  the  board.  The  nails  for 
center  were  left  projecting  about  ^  inch  to  make 
a  definite  point  for  the  level  rod.  The  length 
of  sights  was  from  800  feet  to  2400  feet,  an 
average  being  perhaps  somewhere  between  1100 
feet  and  1400  feet.  Readings  for  levels  were 
taken  at  each  set-up  so  that  two  sets  of  notes 
were  kept  and  two  determinations  of  the  height 
of  each  station  secured,  except  between  El  Cas- 
tillo and  San  Carlos,  when  level  readings  were 
only  taken  at  everj'  other  set-up  and  only  one 
line  of  levels  taken ;  what  was  done  will  perhaps 
be  made  clearer  by  the  following  explanation: 
Starting  with  the  instrument  at  "a"  take  a 
backsight  on  the  B.  M.  and  foresight  on  "  b  " 
and  also  foresight  on  "  a "  by  measuring  down 
from  the  cross-hairs.  This  gives  one  elevation 
of  "a"  and  one  of  "b."  Then,  after  having 
previously  set  the  instrument  half-way  between 
B.  M.  and  ''  a  "  and  obtained  a  second  elevation 
of  "  a,"  set  at  "  a  "  using  the  second  elevation 
of  "  b,"  take  a  backsight  on  it  and  a  foresight 
on  "c"  and  one  on  "b."  We  now  have  two 
elevations  of  "  b."  Then  set  at  "  c  "  and  using 
the  first  elevation  of  "  b  "  take  a  backsight  on  it 
and  foresight  on  "  d  "  and  "  c  "  and  so  on.     The 


382 


NICARAGUA   CANAL  COMMISSION 


readings  taken  when  the  instrument  is  at  "a," 
"c,"  "e,"  cte.,  fomi  one  set  of  notes  and  con- 
stitute one  line  of  levels.  Those  taken  with  the 
instrument  at  "  o,"  "  b,"  "  d,"  "  f,"  etc.,  form 
another  set  of  notes  and  another  line  of  levels. 
Each  set  of  notes  has  the  elevation  of  each  point 
and  the  average  is  taken.  It  will  be  noticed 
that  what  is  a  backsight  on  one  line  is  a  fore- 
sight on  the  other  line,  and  vice  versa,  so  that 
errors  coming  from  unequal  foresight  and  back- 
sights due  to  imperfect  adjustment  for  collima- 
tion  are  perfectly  eliminated. 

.While  this  leveling  was  being  done  the  weath- 
er was  nearly  always  cloudy  and  cool.  Few 
sights  were  taken  when  there  was  any  hot  sun- 
shine. The  sights  were  nearly  all  across  the 
water  surface  and  the  temperature  of  air,  earth 
and  water  was  practically  the  same. 

In  Appendix  IX  is  a  table  showing  the  results 
of  this  leveling  compared  with  that  obtained  by 
the  Precise  Level  party  between  Ochoa  and  San 
Carlos.  The  initial  difference  of  elevation  at 
Ochoa  was  0.500  and  this  difference  varies  by 
very'  small  amounts  as  the  different  points  were 
touched  until  a  point  is  reached  above  Castillo, 
when  the  discrepancy  rises  to  0.36  at  San  Carlos. 
Over  this  part  only  one  line  of  levels  were  run 
and  perhaps  some  allowance  should  be  made  on 
account  of  its  being  at  the  beginning  of  our 
work.  Respectfully, 

S.  S.  Evans, 
Assistant  Engineer. 


MEMORANDUM  IN  REFERENCE  TO 
FRANCIS  LEE  STUART'S  REPORT 
UPON  THE  SAN  JUAN  RIVER. 

Distances  and  fall  in  river  supplied  by  A. 
Onderdonk  from  maps  and  notes  of  the  Nicara- 
gua Canal  Commission's  Surveys  of  San  Juan 
and  Colorado  rivei"s.  The  distances  are  taken 
along  the  axis  of  the  river. 

The  elevation  of  the  water  in  Lake  Nicaragua 
was  taken  at  104.4  which  was  its  elevation  at 
the  time  the  surveys  were  commenced,  and  the 
elevation  of  the  sea  was  taken  at  0.0. 

The  following  is  a  table  of  the  distances  and 
elevations:  i>i8t-  ei®v. 

Miles.  Feet. 

Lake  Nicaragua — San  Carlos . .     0.00  104.4 

Mouth  of  Savalos  river 27.16  99.0 

Bottom  Toro  rapids 28.86  91.7 

Beginning  Castillo  rapids 36.84  90.5 

End  Castillo  rapids 37.22  84.5 

Punta  Gorda 39.30  82.0 

One  mile  below  Machuca 49.92  56.0 

Boca  San  Carlos 64.71  55.0 

Rio  San  Juanillo 97.73  25.0 

Boca  Colorado   103.01  21.0 

Sea  via  San  Juan  river 121.66  0.0 

Sea  via  San  Juan  and  Parada 

creek 115.04  0.0 

Sea  via  Colorado  river 126.71  0.0 

Sea  via  Colorado  and  Cano  Bra- 
vo     122.71  0.0 

Andrew  Onderdonk, 
Assistant  Engineer. 


APPENDIX  v.— REPORT   OF  F.   L.   STUART,   ASSISTANT  ENGINEER 


383 


TABLE  No.  1  SHOWING  VELOCITIES  IN  RIVER  AND  CANAL  SECTIONS,  ASSUMING  VARIOUS  QUANTITIES 
OF  WATER  AS  PASSING  FORT  SAN  CARLOS,  AND  BEING  AUGMENTED  PROPORTIONALLY  TO  THE 
DISTANCE  SO  THAT  THE  SUM  OF  THE  INCREMENTS  WILL  BE  50,000  CUBIC  FEET  PER  SECOND  WHEN 
BOCA  SAN  CARLOS  IS  REACHED. 

Computations  made  for  an  elevation  of  water  surface  at  110. 
Quantity  passing 

Fort  San  Carlos 10,000  20,000         30,000  33,000  40,000  50,000 


Location. 


Station  268, 
't  «80. 
'♦       1265 


Cut-off  Palo  de  Arco 

River 

Canal 


Cut-off  Sombrero  de  Cuero 

River 

Canal 


River 
Canal 


Cut-off  Conchuda 
Canal 


Q. 


15,000 
20,000 
30,000 


11,190 
11,310 


17,230 
17,770 


V. 


0.99  25,000 
1.2530,000 
1.74  40,000 


088 
0.98 


Q. 


V. 


64 

89 


16,1701 
16,330  1 


1.6622,160 
2.74122,840 


12,4701.20 
22,530|2.26 


43,350 
16,650 


1.20 
1.44 


27 
42 


35,000 
40,000 
50,000 


21,140 
21,360 


14  27,000 
53  27,910 


16,0401 
28,960  2 


50,580 
19,420 


54 
91 


40 

68 


19,610 
35,390 


57,810 
22,190 


2.30 


2.50 
•>.91 


38,000 


43;000 
53,000 


V. 


2.50 
2.70 
3.0« 


1.6622,6301.78 
1.86  22,870il.90 


2.62  28,550 
4.32  29,450 


1.88 
3.56 


20,«70 
37,330 


I 

1.60=59,900 
1.92  23,100 


2 .  76 
4.55 


Q. 


45,000 
50,000 
60,000 


26,120 
26,390 


32,020 


2.97:55,000 
3.1460,000 
3.4870,000 


2.05  30,700 
2.30  31,800 


3.10;36,900 
33,98015. 11 138,100 


1.99  23,180  2.22  26,700 


3.75 


41,820  4.2148,300 


1.6565,0401.80  72,200 
2.00  24,960,2.16  27,800 


V. 


3.62 
3.77 
4.07 


2.41 
2.7 


•>  77 


3.56 

5.88 

2.59 
4.86 


2.00 
2.41 


Remarks. 


Width  on  bottom  150^ 


Width  on  bottom  250^ 


Q=Cubic  feet  per  second.     V= Velocity,  feet  per  second. 

TABLE  No.  2  SHOWING  VELOCITIES  IN  RIVER  AND  CANAL  SECTIONS,  ASSUMING  THE  CURRENT  AS  START- 
ING AT  MACHUCA  AND  BEING  AUGMENTED  PROPORTIONALLY  TO  THE  DISTANCE  SO  THAT  THE  SUM 
OF  THE  INCREMENTS  SHALL  BE  30,000  AND  40,000  CUBIC  FEET  PER  SECOND  WHEN  FORT  SAN  CARLOS 
IS  REACHED. 

Computations  made  for  an  elevation  of  water  surface  at  110. 

Sum  of  Increments  at  Fort  San  Carlos 40,000  30,000 


Location. 


V. 


Q. 


V. 


Cut-off  Sombrero  de  Cuero 

River  . 
Canal  . 

River  . 
Canal  . 

Cut-off  Palo  de  Arco 

River  . 
Canal  . 

Station  12fJ5 

680 

268 


7,370 
7,630 

5,330 
9,670 


ic 


»( 


.13,680 
.13,820 

.19,000 
.29,000 
36,000 


0.69 
1.18 

0.51 
0.97 

1.07 
1.20 

1.10 
1.82 
2.37 


4,900 
5,100 

3,070 
tJ,930 

10,150 
10,250 

14,700 
22,000 
26,700 


0.48 
0.79 

0.29 
0.69 

0.80 
0.90 

0.85 
1.38 
1.75 


Width  on  bottom,  150^ 
Width  on  bottom,  250^ 


Q=Cubic  feet  per  second.     V= Velocity,  feet  per  second. 

TABLE  No.  3  AS  ABOVE  EXCEPT  THAT  THE  CURRENT  IS  ASSUMED  TO  START  FROM  BOCA  SAN  CARLOS, 
AND  THAT  THE  SUM  OF  THE  INCREMENTS  AT  FORT  SAN  CARLOS  SHALL  BE  50,000  AND  30,000 
CUBIC  FEET  PER  SECOND. 

Sum  of  increments  at  Fort  San  Carlos 50,000  30,(K)0 


Location. 


Q. 


V. 


Q. 


V. 


Cut-off  Sombrero  de  Cuero 

River 11,760 

Canal 11,240 

River 8,000 

Canal 15,000 

Cut-off  Palo  de  Arco 

River 18,890 

Canal 18,610 

Station  1265 30,000 

*'         680 40,000 

268 45,000 


4i 


1.13 
2.74 

0.79 
1.50 

1.48 
1.63 

1.74 
2.50 
2.97 


7,100 
6,»00 

5,000 
9,000 

11,350 
11,150 

18,000 
24,000 
27,000 


0.69 
1.06 

0.49 
0.90 

0.89 
0.97 

1.05 
1.50 
1.77 


Width  on  bottom  150^ 


Width  on  bottom  250^. 


384 


NICARAGUA   CANAL  COMMISSION 


TABLE  No.  4  SHOWING  VELOCITIES  IN  RIVER  AND  CANAL  SECTIONS  BELOW  MACHUCA  FOR  VARIOUS 

QUANTITIES  AND  ELEVATIONS  OF  THE  WATER  SURFACE. 

Q  =  100,000. 
Elevation  W.  S 110  105  91.0  H2A  68.2 


Location. 


Q. 


V. 


Q. 


V. 


Q. 


V. 


Q. 


V. 


Q. 


V. 


Cut-off  Conchnda 

River 72,200  2.01 

Canal 27,800  2.3« 

Station  3052 100,000  2.98 


73,300         2.28 
26,700         2.70 

100,000         3.24 


60,100         2.49 
39,900         3.37 

100,000         4.10 


52,400         2.73 
47,600         4.10 

100,000         4.48 


50,000  3.77 

50,000  4.  as 

100,000  6.07 


Q= 80,000. 
Elevation  W.  S 110  105  91.6 

Location.  Q.  V.  Q.  V.  Q.  V. 

Cnt-off  Conchnda 

River 57,760         1.61  58,640         1.78  48,080         2.03 

Canal 22,240         1.89  21,360         2.16  31,920         2.70 

Station  3052 80,000         2.38  80,000         2.59  80,000         3.28 

Q =50,000. 
Elevation  W.  S 110  105  91.6 

Location.  Q.  V.  g.  V.  Q.  V. 

Cut-off  Conchnda 

River 36,100         1.00  26,650         1.11  80,050         1.25 

Canal 13,900         1.18  13,850         1.35  19,950         1.68 

Station  3052 50,000         1.49  50,000         1.62  50,000         2.05 

Q= 80,000. 
Elevation  W.  S 110  105  91.6 

Location.  g.  V.  Q.  V.  Q.  V. 

Cnt-off  Conchnda 

River 21,660         0.60  21,990         0.67  18,080         0.74 

Canal 8,840        0.71  8,010        0.81  11,970         1.11 

Station  8052 30,000         0.89  80,000         0.97  80,000         1.23 

Q=Cubic  feet  per  second.     V=Velocity,  feet  per  second. 


82.4 


68.2 


Q. 


V. 


Q. 


41,920 

2.21 

40,000 

2.23 

89,080 

3.28 

40,000 

3.46 

80,000 

3.58 

80,000 

4.86 

82.4 


68.2 


Q. 


V. 


Q. 


26,200         1.87 
28,800         2.05 

50,000         2.24 


82.4 


25,000 
25,000 


1.89 
3.16 


50,000         3.04 


68.2 


Q. 


V. 


Q. 


V. 


15,720         0  83 
14,280         1.38 


80,000 


1.84 


15,000 
15,000 


0.83 
1.80 


80,000         1.82 


APPENDIX   v.— REPORT   OF   F.    L.    STUART,   ASSISTANT   ENGINEER 


385 


SKETCHES  OF  VARIANTS. 

Leoji^ths  of  Variants  are  from  Sta.  O  at  Fort  Sao  Carlos  to  Boca  San  Carlos. 

Prices  nsed  for  determining  comparative  costs. 

All  earth  and  silt  excavation 9  0.37  per  yard. 

Hard  and  soft  rock 0.«)3        '» 

Dam  Masonry,  concrete 8.30        *» 

Clearing 75.00  per  acre. 

Clearing  and  grubbing 100.00        " 

Lock  cost  depending  on  lift. 

Dam  construction  other  than  masonry  depending  on  location. 


nrr 


■73»- 


r* 


aA.7A.eA.5A   VA/TfAfrr 


lAHT      T 


COSr.$2S  «27  620.00 
LENGTH.  Se.94   HILCS 


\ 


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25 


APPENDIX  VI 


REPORT  OF  H.  H.  TRUNDLE 

Assistant  Engineer 


CONTENTS 

PAGE 

Letter  of  Transmittal 391 

Itinerary 391 

Metliods  adopted  in  the  Work 392 

Ilesiilta  of  Sur\^ev 393 

Preliniinarv  Lines  for  Low-Level  Canal .393 

«■ 

Methods  Employed  on  Preliminary  Lines 394 

OiRce  Work 394 

AVaste-AVeirs    395 

Locks 395 

Dams   396 

Canal  Embankments 396 

Selected  Ronte 396 

(nimate    398 

Ve^retation    398 

(loological  Formation   399 

Labor    399 

Animal  Life 399 

List  of  Assistants — Field  Work 400 

List  of  Assistants — Office  Work 400 


APPENDIX  VI 


Washington,  D.  C,  May  5,  1899. 

Me.  E.  S.  Wheeler, 

Chief  Engineer,  Nicaragua  Canal  Commia- 
sion,  Washington,  D.  C. 

Sir: — I  have  the  honor  to  submit  to  you 
the  following  general  report  of  work  done  under 
my  direction  for  the  Nicaragua  Canal  Commis- 
sion of  1897. 

Very  respectfully, 

H.  H.  Trundle, 
Assistant  Engineer. 

Report  of  Service  with  the  Nicaragua 
Canal  Commission. 

In  compliance  with  instructions  from  Rear- 
Admiral  John  G.  Walker,  President  of  the 
Commission,  I  reported  at  the  Commission's 
headquarters  in  New  York,  November  25,  1897. 
I  there  received  instructions  to  go  to  the  offices 
of  the  Maritime  Canal  Company  and  take  copies 
of  such  notes  as  would  be  of  use  in  retracing 
this  canal  company's  location  between  Grey- 
town  (San  Juan  del  Norte)  and  Ochoa.  I  was 
engaged  on  this  work  until  December  5.  Dur- 
ing this  time  I  found  the  secretary  of  the  Canal 
Company,  Mr.  Thos.  B.  Atkins,  very  courteous 
and  accommodating. 

On  December  5,  we  sailed  from  New  York 
on  the  U.  S.  gunboat  "  Newport "  and  anchored 
at  Key  West  December  11,  about  11  A.  M., 
where  we  remained  until  the  following  even- 
ing, coaling.     About  6  P.  M.,  December  12,  we 


weighed  anchor  and  sailed  for  Greytown  arriv- 
ing at  that  port  at  11  A.  M.,  December  17.  We 
had  pleasant  weather  during  the  entire  trip 
which  was  very  fortunate  for  us,  since  owing  to 
the  crowded  condition  of  the  sliip,  we  would 
otherwise  have  been  verv  uncomfortable. 

Immediately  after  casting  anchor  off  Grey- 
town  I  was  detailed  to  accompany  the  disburs- 
ing officer  ashore  and  assist  in  arranging  for 
temporary  quarters  for  the  expedition.  AVe 
crossed  the  Greytown  bar  in  one  of  the  tugs  of 
the  Caribbean  and  Pacific  Transit  Company, 
manned  bv  Carib  Indians  who  showed  them- 
selves  to  be  verv  efficient  boatmen.  After  cross- 
ing  the  bar  we  took  canoes  and  proceeded  up  one 
of  the  channels  through  which  the  San  Juan 
river  empties  its  waters  into  the  Caribbean  sea, 
and  through  Greytown  lagoon  to  Greytown. 
This  channel  is  very  tortuous,  about  fifty  feet 
wide  and  three  miles  long. 

After  enjoying  a  good  dinner  at  Sandusky's, 
Mr.  Boyd  Ehle  and  myself  were  instructed  to 
go  to  the  quarters  built  by  the  Canal  Company 
in  1889  at  La  Fe  and  report  on  their  adapta- 
bility as  temporary  quarters  for  the  expedition. 
We  found  the  buildings  in  fairly  good  condi- 
tion with  the  exception  of  the  stoops  or 
porches^,  which  had  been  exjwsed  to  the  weather 
and  were  considerably  decayed.  The  frame- 
work of  these  buildings  is  of  pine,  the  roof  and 
sides  being  covered  with  corrugated  galvanized 
iron.     They  rest   on  piles  which   are   heavily 


392 


NICARAGUA  CANAL  COMMISSION 


coated  with  pitch.  The  first  or  lower  floors  are 
about  four  feet  above  the  gi'ound,  thus  allowing 
a  current  of  air  beneath  tlieni.  The  framework 
for  the  buildings  was,  I  understand,  shipped 
readv  framed  from  tlie  United  States.  After 
looking  over  the  largest  building  as  carefully  as 
circumstances  would  ])ennit,  we  decided  that  it 
was  large  enough,  and  wnth  some  light  repairs 
would  be  safe  as  temporary  quarters  for  the  en- 
gineer force. 

AVhen  this  report  was  made  to  the  disbursing 
officer,  he  instnicted  me  to  em]>loy  the  necessiiry 
labor  and  j)rej)are  quartei*s  for  the  reception  of 
the  entire  engineer  force  on  December  18.  The 
quarters  were  gotten  in  shape  and  a  meal  pre- 
pared by  2.30  P.  M.,  Mr.  Ehle  having  attended 
to  getting  provisions,  cooking  utensils,  etc.,  from 
the  (Commission's  supply  at  Greytown  and  shij> 
ping  them  to  La  Fe.  Lieut.  G.  C.  Ilanus,  U. 
S.  X.,  arrived  with  the  first  detachment  of  en- 
gineers from  the  "  Newport "  about  1.30  P.  M., 
and  took  charge  of  the  camp. 

On  December  22,  I  received  vour  letter  of 
instructions,  dated  December  21,  directing  me 
to  retrace  the  (^anal  Company's  location  between 
(ireytown  and  Ochoa  and  assigning  me  assist- 
ants for  the  work.  The  object  of  this  work 
being  to  verify  the  Canal  Company's  maps  and 
l)rofiles,  establish  a  base  line  from  which  sur- 
veys for  changes  in  location  could  be  made  if 
found  necessarv  or  desirable,  and  to  collect  suffi- 
cient  data  to  enable  the  Commission  to  make  an 
independent  estimate  over  the  route. 

The  interv'al  between  December  22,  and  De- 
cember 30,  was  employed  in  getting  together 
camp  and  instrumental  outfits,  adjusting  instru- 
ments, procuring  laborers  and  exploring  some  of 
the  line  in  immediate  vicinity  of  Greytown. 
Actual  w^ork  in  the  field  was  commenced  Decem- 
ber 30. 


The  canal  between  Grevtown  and  thesite  for 
Lock  No.  1  is  almost  entirely  in  swamp  and  for 

this  reason  it  was  considered  unnecessarv  to  run 

ft 

the  center  line  through  this  portion.  Instead, 
we  retraced  the  center  line  of  the  railroad  as  far 
as  it  had  been  constnicted,  which  is  about  Hi 
miles.  Elevations  of  swamps  on  either  side  of 
the  railroad  were  taken  at  frequent  intervals, 
and  at  longer  intervals,  cross  lines  were  run  over 
to  the  center  line  of  the  canal,  thus  verifying 
the  elevation  of  various  points  on  the  canal  line. 
The  railroad  line  was  joined  to  the  canal  location 
at  the  edge  of  swamp  just  east  of  the  proposed 
site  for  Lock  No.  1,  by  a  cross  line;  by  this 
means  we  were  enabled  to  verify  the  length  of 
the  canal  between  Greytown  and  this  junction. 
West  of  this  junction  the  center  line  of  the  canal 

was  retraced  and  verified  all  the  wav  to  Ochoa. 

t.' 

^[ethods  Adopted  in  the  AVork. 

All  angles  were  measured  carefully  with  a 
transit,  deduced  bearings  being  carried  through 
as  a  check  to  the  reading  of  the  angles.  Owing 
to  the  density  of  the  forest  and  the  almost  inces- 
sant rain  or  cloudiness  it  was  imi>racticable  to 
check  the  work  as  often  as  I  would  have  liked 
bv  sidereal  observations.  Our  transits  were  not 
fitted  with  solar  attachments. 

The  measurement  was  done  almost  exclusively 
with  steel  chains  100  feet  long.  These  chains 
were  checked  and  adjusted  by  comparison  with 
a  steel  tape  at  intervals  of  about  two  weeks.  Es- 
ix?cial  care  was  taken  in  the  chaining,  plumb 
bobs  being  used  on  all  rough  and  broken  ground. 
Quite  a  number  of  the  Canal  Company's  points 
were  found  by  which  we  were  enabled  to  com- 
pare our  measurements  with  that  of  the  com- 
pany. At  a  few  points,  where  the  line  ran  in 
the  Deseado  river,  the  stadia  was  used,  being 
checked  by  backsight  readings. 


APPENDIX^  VI.— REPORT   OF   H.    H.   TRUNDLE,   ASSISTANT   ENGINEER 


393 


Elevations  of  surface  were  taken  with  a  wye 
level  and  target  rod  at  intervals  of  100  feet  and 
at  such  intermediate  points  as  were  necessary  in 
order  to  produce  a  close  and  accurate  profile. 
"While  we  were  retracing  this  line  Mr.  Stephen 
Harris  was  running  a  "  precise  level ''  line  over 
practically  the  same  ground  and  we  were  able  to 
check  up  on  his  elevations  at  intervals  of  from 
one  to  five  miles.  The  greatest  difference  per 
mile  which  occurs  between  our  levels  and  those 
of  the  precise  level  party,  is  shown  by  Mr.  Har- 
ris' report  to  be  between  our  initial  bench  mark, 
in  the  company's  machine  shops  at  Oreytown, 
and  a  point  on  the  railroad  line  4.30  miles  out 
of  Grevtown.  This  difference  amounts  to  about 
50/1000  of  a  foot  per  mile,  our  elevation  being 
the  lower. 

When  our  line  was  found  to  be  onlv  a  short 
distance  from  the  Canal  C(mipany's  location, 
such  distance  was  noted  and  cross  sections  were 
taken  at  suflSciently  close  intervals  to  enable  us 
to  plot  an  accurate  profile  directly  on  the  Canal 
(.Company's  line.  Other  cross  sections  were  taken 
to  verify  the  contour  maps  of  the  line.  At  no 
point  on  the  route  was  our  line  more  than  30 
feet  from  that  of  the  (/'anal  Company. 

In  making  this  sun^y  we  used  ten  cam])s, 
their  average  distance  apart  (measured  on  the 
trails)  was  about  three  miles.  They  were  not, 
however,  placed  at  equal  intervals,  but  at  longer 
or  shorter  intervals  to  equalize  for  the  difiicul- 
ties  in  \valking  or  packing  through  the  country. 
The  greatest  distance  between  any  two  camps 
was  7i  miles,  while  the  least  was  1^  mile«.  All 
camps,  with  the  exce])ti(Ui  of  (me,  were  built  by 
independent  forces  organized  for  the  puq)ose. 
Thev  were  without  sides  or  walls  and  were  cov- 
ered  with  thatch  made  of  some  one  of  the  manv 
varieties  of  palm  found  in  this  section.  That 
known  as  the  "  Suita  Palm  "  is  one  of  the  best 


for  the  purpose  and  is  tied  to  the  frame  work  of 
the  roof  with  a  species  of  vine  known  as  "be- 
juca. 

In  making  this  survey,  about  60  miles  of  line 
was  run,  which  mav  be  divided  as  follows: 

Retraced  railroad  line 11.4  miles. 

Retraced  canal  line 22.1      " 

Tie,    auxiliary    and    topography 

lines   ....'. .26.5     " 

The  transit  party  reached  Oclioa  May  7,  1808. 
Owing  to  the  sickness  of  our  levelman  during 
the  latter  part  of  the  work,  the  level  party  did 
not  reach  Ochoa  until  Mav  15. 

Results  of  Survey. 

(1)  The  maps  and  profiles  published  by  the 
Canal  Company  covering  this  section  were  found 
to  be  correct  and  reliable. 

(2)  The  lo(»ation  was  found  to  be  good  for  the 
adopted  system  of  locks  and  dams. 

(3)  Suflicient  data  was  obtained  to  enable  the 
Commission  to  make  an  independent  estimate 
through  this  section. 

This  route  has  been  so  thoroughly  discussed 
in  previous  publications  that  I  deem  it  unneces- 
sary for  me  to  make  any  further  description  of  it. 

Preliminary  Lines  for   Low-Level  Canal. 


The  next  work  assigned  me  was  the  running 
of  preliminary  line  from  the  mouth  of  Em- 
bankment creek  in  an  easterlv  direction  to- 
ward  (ireytown.  Embankment  creek,  as  will  be 
seen  by  reference  to  a  map  of  this  part  of  the 
work,  is  a  short  distance  down  the  San  Juan 
river  from  Ochoa.  This  work  was  commenced 
May  11,  and  the  routes  of  the  preliminary  lines 
run  by  me  may  be  briefly  described  as  follows: 
The  first  line  begins  on  the  bank  of  the  San 
Juan  river  near  the  mouth  of  Embankment  creek 


394 


NICARAGUA  CANAL  COMMISSION 


and  follows  it  to  its  head.  It  then  crosses  a 
divide  into  the  valley  of  the  Cano  Leonora  and 
follows  this  to  its  junction  with  the  Rio  Danta 
in  Florida  lagoon.  From  this  point  the  line 
passes  through  the  Florida  lagoon  and  down  the 
Kio  Danta  to  within  about  a  mile  of  it*?  mouth; 
here  the  line  leaves  the  Danta  and  crosses  a  strip 
of  land  about  two  miles  wide  to  the  Rio  San 
Francisco;  it  then  crosses  the  Rio  San  Fran- 
cisco and  follows  down  the  southern  slope  of  the 
San  Francisco  hills  to  their  eastern  end  where  it 
joins  with  the  preliminary  line  run  by  Assistant 
Engineer  Boyd  Ehle. 

After  joining  w^ith  Mr.  Ehle's  work  at  the 
San  Francisco  hills,  we  moved  camp  down  the 
San  Juan  river  and  ran  ^ the  necessarv  lines  for 
filling  in  a  gap  in  the  topography  between  the 
eai?tem  slope  of  the  Sarapiqui  ridge  and  a  point 
about  1^  miles  east  of  the  San  Juanillo  river,  on 
Mr.  S.  S.  Evans'  preliminary  line  from  Grey- 
town.  About  3^  miles  of  this  work  was  done 
by  Mr.  Evans'  party  under  my  direction,  Mr. 
Evans  at  the  time  being  unable,  on  account  of 
sickness,  to  superintend  the  work. 
Methods  Emplovkd  on  Prelimixauy  Lixes. 

All  preliminary  and  many  of  the  principal 
topography  lines  were  run  with  the  same  care 
and  accuracy  as  was  used  in  retracing  the  Ca- 
nal Company's  location.  On  minor  topog- 
raphy lines  the  compass  was  used  generally. 
The  hand  level  was  used  for  some  toj^ography, 
though  not  to  any  great  extent,  or  on  any  of  the 
principal  topographical  base  lines. 

In  taking  the  topography,  I  endeavored  to  get 
sufficient  data  to  make  an  accurate  contour  map 
which  would  cover  at  least  1000  feet  on  each 
side  of  what  seemed  to  be  the  rational  location 
for  the  canal  through  the  section  traversed.  At 
all  points  w^here  there  was  any  doubt  as  to  the 
proper     location,     alternate     lines    were     run. 


Wherever  it  could  be  conveniently  done  these 
sur\'^eys  were  tied  by  cross  lines  to  points  on  the 
survey  of  the  San  Juan  river. 

We  completed  the  field  work  and  moved  into 
headquarters  near  La  Fe  August  28,  where  we 
remained  until  September  16,  this  interval  being 
employed  in  plotting  up  field  notes. 

On  September  IG,  we  sailed  from  Greytown 
on  the  Atlas  Line  steamer  "  Altai,"  arriving  in 
Xew  York  September  27,  and  then  proceeded 
to  Washington  where  offices  had  been  procured. 

Office  AVork. 

The  survey  notes  arrived  in  Washington  Oc- 
tober 0,  and  I  was  assigned  the  making  of  loca- 
tions and  estimates  for  a  low-level  canal  between 
the  eastern  slope  of  the  Sarapiqui  ridge  and  the 
point  at  which  the  finally  adopted  location  en- 
ters the  San  Jiian  river  on  the  west  side  of  the 
R<H*a  de  San  Carlos  ridge.  Later  I  was  assigned 
the  work  of  making  plans  and  estimates  of  cost 
of  masonry  locks  having  various  lifts,  and  of 
masonrv  dams  above  Boca  de  San  Carlos  and  at 

I 

!Nrachuca  rapids,  having  different  crest  eleva- 
tions; this  data  being  necessary  for  making 
comj)arative  estimates  on  locations  for  different 
svsteins  of  locks  and  dams. 

The  first  few  weeks  in  office  were  devoted 
largely  to  the  plotting  and  comparison  of  toiX)g- 
raphy  notes  and  the  making  of  a  complete  topo- 
graphical map  covering  the  entire  section 
through  which  the  locations  w^ere  to  be  made. 
Practically  all  of  the  to])()grapliy  notes  had  been 
plotted  on  brown  paper  maps  before  we  left 
Nicaragua  ;\they  were,  however,  in  disjointed 
sections  and  had  to  be  combined. 

Locations  and  estimates  were  made  for  sys- 
tems of  locks  and  dams,  east  of  Lake  Nicaragua 
as  follows: 

For  five  locks  with  one  and  two  dams. 


APPENDIX  VI.— REPORT   OF  H.   H.   TRUNDLE,  ASSISTANT   ENGINEER 


395 


For  six  locks  with  one,  two  and  three  dams. 

For  seven  locks  with  one,  two  and  three  dams. 

For  eight  locks  with  one,  two  and  three  dams. 

The  above  estimates,  eleven  in  all,  were  made 
for  a  canal  150  feet  wide  at  bottom.  Some  al- 
ternate estimates  were  also  made  on  these  sys- 
tems having  the  width  at  bottom  100  feet 
through  hard  rock  sections  and  150  feet  else- 
where. 

An  additional  estimate  was  made  for  a  canal 
using  a  system  of  six  locks  and  three  dams  east 
of  Lake  Nicaragua  and  having  a  bottom  width 
of  100  feet.  In  this  estimate  passing  points, 
having  a  bottom  width  of  150  feet  and  length  of 
2000  feet,  were  provided  for  at  intervals  of 
about  five  miles. 

In  selecting  a  location,  the  one  used  for  esti- 
mates has  been  adopted  only  after  a  comparison 
witli  all  alternate  lines  which  have  suggested 
themselves,  and  often  only  after  complete  alter- 
nate estimates  have  been  made.  In  general,  the 
location  adopted  for  making  the  estimate  for  a 
system  of  six  locks  and  three  dams  has  been 
found  to  be  best  for  any  of  the  above  mentioned 
systems.  For  some,  slight  divergences  are  nec- 
essary in  order  to  secure  suitable  locations  for 
locks.  The  grades  have  been  so  adjusted  as  to 
make  the  lifts  of  all  locks  in  each  system  equal 
at  niaxiyiuni  stages  of  water. 

All  work  has  been  done  on  contour  maps 
showing  10-foot  contours'  and  plotted  to  a  scale 
of  400  feet  to  the  inch.  All  estimates  of  exca- 
vation have  been  derived  from  plotted  cross  sec- 
tions, the  areas  of  which  have  been  taken  off 
with  planimeters.  Profiles  are  plotted  with  a 
vertical  scale  of  20  feet  to  an  inch  and  hori- 
zontal scale  of  400  feet  to  an  inch  and  show  the 
geological  classifications  as  determined  by  Dr. 
C.  W.  Hayes  of  the  U.  S.  Geological  Survey, 
from  borings  and  observations  in  the  field. 


It  is  of  course  impossible  to  determine,  intel- 
ligently, the  proper  number  of  locks  and  dams  to 
be  used  on  the  entire  svstem  east  of  Lake  ^ica- 
ragua,  from  results  obtained  from  estimates  on 
that  section  of  the  line  between  the  Sarapiqui 
and  San  Carlos  ridges.  For  this  section  alone, 
however,  the  results  seem  to  point  to  the  selec- 
tion of  either  the  six-  or  eight-lock  systems,  for 
any  number  of  dams.  Both  of  these  systems 
show  verj'  small  amounts  of  high  embankment 
and  arc  everywhere  high  enough  above  the  San 
Juan  river  to  be  out  of  danger  of  floods.  There 
is  a  very  small  portion  of  the  embankment  on 
either  of  these  svstems  that  would  have  a  head 
exceeding  15  feet  of  water  against  it,  and  over 
a  large  percentage  of  it  the  head  would  be  less 
than  10  feet.  The  eight-lock  system  gives  a 
little  less  head  of  water  against  embankments 
and  costs  something  more.  If  only  one  dam 
should  be  used,  the  eight-lock  system  would 
have  the  disadvantage  of  having  one  double  lift 
lock. 

Waste- Weirs. 

Estimates  for  this  section  include  about  2800 
lineal  feet  of  waste-weirs  designed  for  the  dis- 
charge of  the  surplus  waters  of  the  various  basins 
traversed. 

The  general  type  of  construction  consists  of  a 
concrete  core  and  crest  backed  with  a  rock  fill. 
Sufficient  length  of  crest  being  given  to  allow 
for  the  maximum  discharge,  with  a  depth  of 
water  not  exceeding  one  foot  over  the  crest. 

Locks. 

The  l(K*ks  are  estimated  to  be  built  of  concrt^te 
and  have  steel  gates;  a  guard  gate  is  provided 
for  at  each  end  of  each  lock,  for  repair  purposes. 
The  general  dimensions  are:  width  between  side 
walls   80   feet;    length   between   corresponding 


396 


NICARAGUA   CANAL  COMMISSION 


points  on  gates  005  feet;  ami  depth  of  water 
over  sills  30  feet.  The  data  for  estimates  and 
the  general  design  for  the  locks  were  derived 
from  the  lock  recently  built  by  the  U.  S.  Gov- 

ernment  for  the  "  St.  ^farv's  Falls  Canal." 

»■ 

Dams. 

All  masonry  dams  were  designed  and  esti- 
mated to  be  constnicted  of  concrete.  Thev  have 
ogee  crests  and  are  founded  on  hard  rock  foun- 
dations. 

In  order  to  avoid  the  necessity  for  excessive 
depths  in  canal  and  locks  it  is  evident  that  the 
surfaces  of  pools  above  dams  should  vary  as  little 
as  possible.  For  this  reason  all  the  available 
crest  of  each  dam  has  been  used  for  spillway. 

For  a  system  in  which  unlv  one  dam  is  used, 
plans  and  estimates  have  been  made  for  gates, 
similar  to  those  used  on  the  Chicago  drainage 
canal,  placed  on  the  crest  of  the  dam  and 
ca])able  of  controlling  the  level  of  Lake  Nica- 
ragua between  the  elevation  of  105  and  110  feet 
above  the  Caribbean  sea;  this  is  also  true  of  the 
dam  nearCsSt  the  lake  in  anv  system  of  locks  and 
dams. 

By  far  the  greatest  difficulty  to  be  encoun- 
tered in  the  construction  of  anv  of  these  dams 
will  be  that  of  coffer-dams  at  Boca  de  San  Car- 
los, the  maximum  depth  of  hard  r(X?k  below 
mean  water  being  about  70  feet.  It  is  believed, 
however,  that  ample  allowance  ha^  been  made 
to  cover  any  possible  contingencies  that  may 
arise  from  that  source. 

Canal  Embankments. 

It  was  endeavored  to  so  make  the  locations 
and  fix  the  grades  as  to  eliminate,  as  far  as  ih)s- 
sible,  embankments  supporting  heavy  heads  of 
water.  Care  was  also  taken  to  avoid  placing 
embankments  on  poor  foundations,  and  for  this 


reason  the  locations  were,  in  many  places, 
thrown  out  of  what  would  otherwise  have  been 
their  proper  position. 

It  is  proposed  to  build  the  embankments  to  an 
elevation  of  eight  feet  above  the  w^ater  iu  the 
canal  opposite.  They  will,  where  practicable, 
be  ])laced,  so  as  to  give  a  berm  fifty  feet  in  Avidtli 
between  the  excavation  and  embankment. 
Since  no  embankment  will  be  required  on  the 
north  side  of  the  canal  through  this  section,  it 
will  be  readily  seen  from  observation  of  maps 
and  j)rofiles  that  there  is  am]>le  material  from  ex- 
cavation for  making  an  embankment  on  the 
south  side  150  feet  wide  if  necessary,  without 
long  haul. 

AVhere  there  will  be  a  head  of  more  than  15 
feet  of  water  against  embankments  they  are  de- 
signed to  be  made  thicker  than  at  other  [wints 
by  an  amount  depending  upon  the  head  of 
water  to  be  supported;  as  an  additional  precau- 
tion slieet  piling  and  clay  are  also  to  be  used  in 
these  places.  All  sheet  piling  is  to  be  driven  to 
a  depth  of  at  least  five  feet  below  the  bottom  of 
the  canal  and  to  extend,  as  a  rule,  well  into  the 
underlying  clay. 

Where  the  embankment  encroaches  on  the 
San  Juan  river  and  is  likelv  to  be  eroded  at 
high  stiiges  of  water,  it  is  intended  to  be  covered 
on  the  exposed  side  with  stone  from  the  caual 
excavations.  At  all  points  where  this  form  of 
construction  is  necessary,  the  rock  for  the  work 
is  found  in  cuts  in  the  immediate  vicinity. 
Spoil  banks  for  the  excess  of  material  from  exca- 
vation will  be  made  in  the  swamps  traversed 
and  ravines  crossed. 

Selected  Route. 

The  Commissioners  have  adopted  the  system 
of  six  locks  and  one  dam  east  of  Lake  Xicaragua 
with  the  dam  located  a  short  distance  above  the 


APPENDIX   VI.— REPORT   OF  H.   H.   TRUNDLE,   ASSISTANT   ENGINEER 


397 


mouth  of  the  San  Carlos  river.  That  part  of 
the  location  for  this  system  through  the  section 

on  which  I  have  made  the  estimates  mav  be 

«■ 

brieflv  described  as  follows: 

It  begins  on  the  eastern  slope  of  the  Sara- 
piqui  ridge  a  distance  of  22.32  miles  from  the 
seven-fathom  curve,  in  the  Caribbean  sea  near 
Greytown.  The  canal  surface  at  this  point  will 
be  at  an  elevation  of  54.75  feet  above  the  Carib- 
bean, it  being  on  the  reach  between  Lock  No.  3 
and  Lock  No.  4.  Thence  the  line  nms  in  a 
westerly  direction  generally  parallel  to  the  San 
Juan  river  passing  through  the  Sarapiqui  ridge, 
along  the  southern  slope  of  the  Tamborcito  ridge, 
through  a  depression  in  the  Tambor  Grande 
ridge  and  along  the  southern  slope  of  the  San 
Francisco  hills  to  the  San  Francisco  river,  which 
it  crosses  about  1400  feet  above  its  mouth. 
From  this  point  the  line  nins  in  a  westerly  di- 
rection, a  distance  of  about  two  miles,  across  a 
strip  of  land  containing  some  small  hills  to  the 
Danta  river,  which  it  strikes  about  a  mile  from 
its  mouth,  following  the  valley  of  the  Danta  up 
to,  and  through  Florida  lagoon  and  thence  up 
the  Cano  Leonora  to  its  headwaters;  the  loca- 
tion having  been  thrown  out  of  the  axis  of  the 
Danta  valley  in  some  places  to  improve  the  align- 
ment and  furnish  better  foundations  for  em- 
bankments. 

Lock  No.  4  is  located  in  the  divide  between 
the  Cano  Leonora  and  Embankment  creek  and 
with  a  lift  of  18.42  feet  gives  an  elevation  of 
73.17  feet  for  the  surface  of  the  reach  above  it. 

Leaving  Lock  No.  4  the  line  passes  down  the 

vallev  of  Embankment  creek  to  within   1500 

«■ 

feet  of  its  mouth,  where  it  diverges  from  the 
valley  by  a  curve  to  the  right,  passing  through 
some  rather  high  hills,  it  runs  in  a  westerly  di- 
rection generally  parallel  to  the  San  Juan  river, 
crosses  the  Cano  Machado  about  200  feet  above 


its  mouth  and  passes  on  to  the  site  for  Lock 
Xo.  5. 

Lock  Xo.  5  is  located  in  a  hill  about  two  miles 
west  of  Cano  Machado  and  with  its  lift  of  18.41 
feet  gives  an  elevation  of  91.58  feet  for  the 
surface  of  the  reach  above  it. 

Leaving  Lock  Xo.  5  the  line  passes  on  to  the 
site  of  Lock  Xo.  6,  crossing  some  hills  and  small 
streams.  This  reach,  it  will  be  noted,  has  some 
high  embankments;  but  since  we  have  an  abund- 
ance of  good  material  here  and  the  underlying 
clay  is  within  easy  reach  of  sheet  piling,  it  is 
believed  that  no  great  amount  of  trouble  will  be 
encountered  in  making  them. 

Lock  Xo.  G  is  located  in  the  eastern  side  of 
the  Boca  de  San  Carlos  ridge  and  with  a  lift  of 
18.42  feet  makes  an  elevation  of  110  feet  for 
the  surface  of  the  reach  above  it.  This  elevation 
is  the  proposed  maximum  for  the  surface  of 
Lake  Xicaragua.  Even  if  the*  surface  of  Lake 
Nicaragua  should  be  allowed  to  reach  an  eleva- 
tion of  112  feet  the  lift  for  this  lock  would  not 
exceed  that  given  above,  since  the  water  surface 
in  the  San  Juan  river  would  have  a  slope  from 
the  lake  amounting  to  as  much  as,  or  more  than, 
two  feet  The  minimum  lift  of  this  lock  would 
be  five  feet  less  than  its  maximum. 

Leaving  Lock  Xo.  6  the  line  passes  through 
the  Boca  de  San  Carlos  ridge  and  enters  the  val- 
lev of  a  small  stream  which  it  follows  to  its 
junction  with  the  San  Juan  river.  The  bottom 
grade  of  this  portion  of  the  canal  is  placed  at 
an  elevation  of  74  feet  so  as  to  allow  for  a  depth 
of  30  feet  of  water  in  the  canal  when  the  sur- 
face of  the  lake  is  at  an  elevation  104. 

For  a  description  of  the  location  w^estward 
from  this  point  I  would  respectfully  refer  you 
to  the  report  of  Francis  Lee  Stuart,  assistant  en- 
gineer. 

The  total  length  of  canal  between  the  eastern 


398 


NICARAGUA  CANAL  COMMISSION 


slope  of  the  Sarapiqiii  ridge  and  the  point  at 
which  the  canal  enters  the  San  Juan  river  west 
of  Boca  de  San  Carios  ridge  is  21.59  miles. 
About  38.5  per  cent,  of  this  line  is  located  on 
curves.  The  minimum  radius  of  curvature  used 
is  3820  feet. 

Observations  on  that  Portion  of  Nicaragua 
Between  Greytown  and  Ochoa. 

Climate. — The  climate  of  this  country  is 
usually  considered  to  be  unhealthful  by  persons 
not  acquainted  with  it.  We  found  it  particu- 
larly healthful  for  a  tropical  country.  We 
were  in  the  field  from  December  30,  1897  until 
August  28,  1898  and  during  that  time  had  not 
a  single  serious  case  of  sickness,  notwithstanding 
the  fact  that  we  were  at  work  in  rain  and  swamps 
about  three-fourths  of  tlie  time. 

Most  of  us  had  one  or  more  light  attacks  of 
fever,  but  thev  invariably  succumbed  readilv  to 
medical  treatment.  These  fevers  were,  I  think, 
usually  if  not  always,  caused  by  the  kind  of 
water  drunk.  I  believe  if  boiled  water  had 
been  strictly  adhered  to,  we  would  have  had 

little  or  no  trouble  from  fevers.     Ofiicers  of  mv 

t. 

party  lost  about  seven  per  cent,  of  the  time  from 
field  work  but  were  seldom  too  sick  for  ofiice 
work  in  camp.  It  should  be  remembered  that 
all  these  men  had  to  be  acclimated.  It  is  likely 
that  extensive  excavation  would  make  the 
country  more  unhealthful. 

The  rainfall  is  excessive  and  retards  to  a  con- 
siderable extent  any  engineering  work  done. 
In  instrumental  work  short  sights  have  to  be 
resorted  to  and  trouble  is  experienced  from 
clouding  of  lenses.  The  average  rainfall  de- 
creases gradually  in  going  westward  from  the 
Eastern  Divide.  There  are  wet  and  dry  sea- 
sons,  but  they  are  divided  by  no  finely  drawn 
lines  as  is  the  case  in  other  parts  of  the  country. 


The  temperature  varies  but  slightly  and  it  is 
very  seldom  excessively  warm.  It  is  very  de- 
bilitating, however,  and  in  my  opinion,  a  man 
cannot  stand  more  than  three-fourths  of  the 
physical  exertion  possible  in  a  temperate  climate. 

Vegetation. — As  would  be  expected  in  a  wet 
country  within  the  tropics,  the  vegetation  is  very 
dense  and  varied.  It  is  impossible  to  make  any 
progress  in  the  forest  without  the  use  of  a 
machete  or  similar  implement  for  cutting  away 
the  tangled  mass  of  undergrowth,  which  of 
course  retards  work  very  much.  In  the  swamps 
the  growth  is  largely  made  up  of  the  many  varie- 
ties of  palm.  On  the  hills  we  find  a  great  variety 
of  timber.  Most  of  it  is  soft  and  unfit  for  use  as 
lumber,  though  a  good  deal  of  it  possesses  suf- 
ficient strength  and  durability  to  make  it  of  use 
in  the  event  of  the  construction  of  the  canal, 
among  which  may  be  mentioned  the  following: 

The  Manwood,  which  is  very  hard,  heavy  and 
durable,  is  said  to  last  for  thirty  years  in  founda- 
tions  but  is  found  only  in  limited  quantities. 

The  Cedar,  which  is  soft,  light  and  durable 
and  grows  to  be  very  large,  hardens  somewhat 
after  working  and  is  found  only  in  small  quan- 
tities in  this  section. 

The  Gavilan,  which  is  found  in  large  quanti- 
ties and  is  hard  but  not  durable,  is  used  to  a 
considerable  extent  for  railroad  ties,  and  its  aver- 
age life  in  this  capacity,  under  well-ballasted 
track,  is  about  a  year  and  a  half. 

There  are  quite  a  number  of  other  woods 
found  in  this  section  that,  with  proper  facilities 
for  working  them,  may  be  profitably  used  for 
stnictures  of  a  very  temporary  character. 

Plaintains  and  bananas  are  the  most  useful 
fruits  grown  in  this  section;  the  natives  live  on 
them  almost  entirely.  They  are  grown  only  in 
quantities  sufficient  to  supply  the  limited  de- 
mand of  the  Greytown  market.     With  increased 


APPENDIX  VI.— REPORT  OF  H.   H.   TRUNDLE,  ASSISTANT   ENGINEER 


399 


demand,  however,  they  would  be  grown  in  large 
quantities.  Coeoanuts  grow  well  along  the 
coast.  Few  garden  products  thrive  owing  to  the 
excess  of  rain. 

Geological  Formation. — I  wish  only  to 
touch  on  this  subject  where  it  affects  directly  the 
construction  of  a  canal  through  this  section,  as  I 
feel  sure  that  it  has  alreadv  been  ablv  treated  by 
our  geologist.  Dr.  C.  TV.  Hayes. 

The  swamps,  after  getting  back  three  or  four 
miles  from  the  coast  are  composed  of  silt  or  allu- 
vium. From  observations  of  the  banks  of 
streams  I  would  class  this  as  a  fairly  good  ma- 
terial for  banks  supporting  small  heads  of  water. 
I  would  not  like  to  depend  on  it  for  embank- 
ments against  large  heads  of  water.  The  banks 
of  the  larger  streams  traversing  these  swamps 
stand  at  steep  slopes,  are  comparatively  hard, 
show  little  or  no  sign  of  seepage  and  are  above 
the  surrounding  swamp.  If  we  go  back  from 
the  bank  a  short  distance  we  find  the  ground 
covered  with  water  to  a  depth  of  from  one  to 
three  feet  and  ver\'  soft.  This  seems  to  show 
that  the  material  hardens  when  drained  and  is 
fairly  imper\'ious  to  water. 

The  hills,  as  is  shown  on  the  classified  pro- 
files, are  largely  composed  of  clay  and  rock. 
The  day  is  red  in  color  and  on  the  surface  shows 
little  gravel.  Its  ability  to  stand  at  steep  slopes 
in  excavation  is  demonstrated  on  the  railroad 
work  done  by  the  Canal  Company  in  1890. 
Here  we  found  cuts  twenty-five  feet  deep  hav- 
ing slopes  of  about  ^  horizontal  to  1  vertical. 
These  slopes,  which  have  stood  for  more  than 
seven  years,  were  apparently  perfectly  stable 
and  the  shovel  and  pick  marks  were  plainly 
visible.     This  clay  would  make  good  puddle. 

The  hard  rock  noted  in  out-crops,  apparently, 
has  no  cleavage.  It  would  not  be  suitable  for 
cut  stone  masonry  but  would  do  well  for  con- 


crete. I  doubt  if  it  could  be  gotten  out  in 
shapes  suitable  for  rubble  masonry  without  great 
expense. 

Labor. — The  laborers  used  for  prosecuting 
the  surveys  were  Jamaica  negroes  and  Nica- 
raguan  natives.  The  natives  were  found  to  be 
very  much  more  satisfactory  for  this  work. 
They  are  more  adept  in  the  use  of  the  machete, 
better  boatmen  and  packers,  more  reliable  and 
amenable  to  discipline  and  very  much  more 
healthy  than  the  Jamaican  negroes.  The 
negroes  I  had  employed  lost  about  seven  per 
cent,  of  the  time  on  account  of  sickness  while 
the  natives  lost  only  about  two  per  cent,  from 
this  cause.  The  natives,  however,  are  too  light 
in  build  to  be  able  to  stand  very  heavy  work. 

In  the  event  of  the  construction  of  the  canal 
practically  all  of  the  labor  will  have  to  be  im- 
ported and  it  is  likely  that  Jamaica  negroes  will 
be  found  best  suited  for  work  on  the  canal. 
They  are  acclimated  to  the  tropics,  available  in 
considerable  numbers  and  with  proper  sanitary 
and  police  regulations  could  probably  be  kept 
healthy  and  made  to  do  good  work.  Skilled 
labor  would  have  to  be  imported  from  some  other 
source. 

Animal  Life. — There  are  quite  a  number  of 
animals  in  this  section,  but  thev  are  seldom  seen 
on  account  of  the  density  of  the  forest.  Among 
those  most  often  seen  mav  be  mentioned  mon- 
keys,  wild  hogs,  pisotes,  wild  cats  and  dantas. 
Pumas  are  very  rarely  seen.  Alligators  are 
numerous  in  the  ponds  and  lagoons.  While  the 
snakes  are  probably  abundant  they  are  seldom 
seen  and,  as  a  rule,  are  very  sluggish.  The 
venomous  varieties  most  usually  seen  are  the 
tamagas,  tobobas  and  coral  snakes.  All  the 
larger  streams  abound  in  fish.  In  the  San  Juan 
we  find  a  number  of  fresh  water  sharks,  the 
largest  I  saw  was  probably  six  feet  long.   Among 


400 


NICARAGUA   CANAL  COMMISSION 


the  game  birds  found  are  pigeons,  ducks  and  wild 
turkeys.  Owing  to  the  density  of  the  under- 
growth and  consequent  difficulty  in  approaching 
it,  game  cannot  be  dejiended  upon  as  a  food 
supply.  Insects  of  almost  everv'  conceivable 
species  are  found  here  in  abundance.  Among 
those  most  objectionable  may  be  mentioned  mos- 
quitoes, alligator  ants,  wasps,  gnats,  ticks  and 
jiggers  or  chigoes.  Domestic  cattle,  hogs  and 
goat5  are  raised  only  to  a  small  extent. 

I  append  lists  of  assistants  I  have  had  both  in 
the  field  and  office  work,  showing  their  positions 
on  the  party  and  the  dates  between  which  they 
were  employed. 


ilr.  Xorris  was  my  first  assistant  on  the  re- 
tracing  of  the  Canal  Company's  route  and  did 
his  work  faithfully  and  well. 

ifr.  Ilankins  was  mv  first  assistant  on  the 
preliminary  work  for  the  low-level  canal. 
While  this  work  was  in  progress  it  was  necessary 
for  me  to  be  away  from  the  party  a  great  deal. 
During  my  absence  ilr.  Hankins  assumed 
charge  of  the  party  and  with  his  long  experi- 
ence in  railroad  location  did  work  that  was 
highly  satisfactory  in  every  way. 

Mr.  Whistler  was  my  principal  assistant  on 
the  office  work  and  has  proved  to  be  thoroughly 
satisfactory  in  every  particular. 


List  of  Assistants  in  Field  Woek. 


Name. 

Position. 

Dates  of  Employment. 

A.  J.  Norris, 

Transitman, 

Dec. 

22,  1897 

to  May  16,  1898. 

Dion  Martinez, 

Levelman, 

Dec. 

22,  1897 

"  May  1,  1898. 

W.  A.  Smith, 

Rodman, 

Dec. 

22,  1897 

"  Jiine  15,  1898. 

P.  J.  TJrune, 

Chainman, 

Dec. 

22,  1897 

"  Aug.  28,  1898. 

Loughlin  McNeil, 

Chainman, 

Dec. 

22,  1897 

"  May  8,  1898. 

R.  H.  Morrin, 

Levelman, 

May 

1,  1898 

"  July  23,  1898. 

H.  C.  C.  Shute, 

Chainman, 

May 

14,  1898 

"  July  9,  1898. 

R.  C.  Wheeler, 

Levelman, 

June 

15,  1898 

"  Aug.  28,  1898. 

L.  Hankins, 

Transitman, 

May 

15,  1898 

"  Aug.  28,  1898. 

List  of  Assistants  on  Office  Work  in  Washington. 

Name. 

Position. 

Dates  of  Employment. 

P.  J.  Erune, 

Computer, 

Oct. 

6,  1898 

to  Dec.  31,  1898. 

A.  J.  Norris, 

Draughtsman  and  Computei 

•,  Oct. 

20,  1898, 

"  Apr.  1,  1899. 

P.   VV.  Evans, 

Computer, 

Oct. 

11,  1898 

"  Dec.  19,  1898. 

Jno.  T.  Whistler, 

Asst.  Engineer, 

Oct. 

17,  1898 

"  the  present. 

W.  D.  Hines, 

Draughtsman, 

Feb. 

1,  1899 

"  Mar.  4,  1899. 

Thos.  F.  Eoltz, 

Computer, 

Mar. 

18,  1899 

"  the  present. 

W.  J.  Maher, 

Computer, 

Mar. 

20,  1899 

"  Apr.  27,  1899. 

W.  C.  Frye, 

Draughtsman, 

ATar. 

23,  1899 

"  Apr.  5,  1899. 

Jno.  B.  Johnston, 

Computer, 

Apr. 

1,  1899 

■"  the  present. 

APPENDIX  VII 


REPORT  OF  BOYD  EHLE 

Assistant  Engineer 


2b 


CONTENTS 

PAGE 

Letter  of  Transmittal '. 405 

Work  in  the  New  York  Office 405 

Arrival  at  Greytown 405 

Trip  up  the  San  Juan  Kiver 406 

Building  a  Camp 406 

Instrumental  Outfit 407 

Organization  of  Party 407 

Tambor  Grande  Embankment  Survey 407 

San  Juan  River  Survey 409 

Methods  of  Work 410 

Camp  near  the  Sarapiqui 410 

Tambor  Grande  Embankment  Survey — Continued 412 

Camp  on  Copalchi  Creek 412 

Camp  on  Cano  Tamborcito 412 

Canal  Location  along  Left  Bank  of  San  Juan 413 

Misterioso  Lagoon 414 

Results  of  Tambor  Grande  Survey 415 

Residts  of  San  Juan  River  Survey 416 

The  Lull  Route,  Variant  I,  Survey 417 

Transportation  Facilities 417 

Timber   417 

Health  of  Party 418 


APPENDIX  VII 


Washington,  D.  C,  April  15,  1899. 

Mr.  E.  S.  "Wheeler, 

Chief   Engineer,    Nicaragua    Canal   Com- 
mission, "Washington,  D.  C. 

Sir: — ^Referring  to  your  letter  dated  Feb- 
ruary 21,  1899,  I  have  now  the  honor  to  trans- 
rait,  herewith,  a  report  of  my  "  entire  operations 
connected  with  the  Nicaragua  Canal  Commis- 


sion. 


>j 


I  am  Sir, 

Your  obedient  servant, 

Boyd  Ehle, 
Assistant  Engineer. 

Report  of  Service  with  the  Nicaragua 
Canal  Cobimission. 

Under  the  direction  of  the  Commission,  I 
began,  August  27,  1897,  collating  the  data  of 
the  Maritime  Canal  Company.  The  note  books, 
maps  and  other  records  had  been  left  in  a  much 
confused  state  and  deposited  in  various  places. 
These  were  all  collected  in  the  office  of  the  com- 
pany at  No.  56  Broad  street.  New  York  city. 
Data  were  transferred  to  the  Commissioner's 
office  at  the  Army  building  in  Whitehall  street, 
as  required,  and  such  details  explained  and  in- 
formation given  as  previous  experience  made 
available.  Some  studies  were  made  of  prospective 
routes  for  survey.  Copies  of  information,  nec- 
essary for  reference  in  Nicaragua,  were  made. 


Maps  and  selected  data  were  packed  and  the  ex- 
pedition sailed  the  morning  of  December  5  from 
the  Brooklyn  Navy  Yard  on  the  U.  S.  Gunboat 
"  Newport"  We  arrived  at  Key  West  Decem- 
ber 11  and  at  Greytown  December  17. 

December  10  the  chief  engineer  instructed 
me  to  make  an  investigation  of  the  possibilities 
for  an  embankment  line  with  a  dam  across  the 
San  Juan  river  at  Tambor  Grande. 

On  my  arrival  at  Greytown,  Admiral  Walker 
instructed  me  to  go  ashore  at  once  and  to  inves- 
tigate the  condition  of  the  Maritime  Company*? 
buildings  with  a  view  to  using  them  as  quarters 
for  .the  expedition  and  if  found  favorable  ta 
make  the  necessary  arrangements.  Accom- 
panied by  Messrs.  Trundle,  Conolly  and  Lee,  I 
went  by  the  ship's  boat  to  the  Atlas  steamer 
"  Alene  "  and  from  her  to  the  Navigation  Com- 
pany's tug  "  Rosita,"  which  transferred  us  to 
the  launch  "  Miria  '*  lying  inside  Harbor  Head 
lagoon.  The  "  Miria  "  attempted  to  take  us  to 
the  Greytown  wharf,  but  after  a  breakdown  and 
much  delay  we  availed  ourselves  of  the  use  of 
a  twenty-foot  steel  canoe  brought  out  by  Mr. 
Barnard  of  the  Commissary  Department,  and 
paddled  to  our  destination.  Mr.  Trundle  and  I 
walked  out  to  La  Fe  and  looked  over  the  build- 
ings as  thoroughly  as  possible  in  the  darkness. 
We  found  them  in  a  neglected  condition,  and 
the  floors  decayed  and  unsafe  in  places.  It  was  * 
decided  to  make  the  best  of  these  conditions,  as 


406 


NICARAGUA  CANAL  COMMISSION 


the  accommodatioiis  in  Greytown  were  inade- 
quate. There  was,  however,  the  disadvantage 
of  being  located  nearly  two  miles  from  the  com- 
missary and  the  business  center,  with  no  efficient 
transportation  service;  however,  this  location  is 
healthier  and  freer  from  distractions  than  Grey- 
to^vn.  The  following  morning  supplies  and  the 
officers'  personal  equipment  were  lightered  to 
La  F6.  A  force  of  men  was  employed  in  clean- 
ing and  preparing  quarters  and  kitchen.  A  num- 
ber of  old  iron  bedsteads  were  set  up  and  util- 
ized by  passing  the  side  bars  through  the  loops 
of  the  canvas  cots  furnished  by  the  Commission. 
A  ground  fire-place  was  prepared  for  cooking, 
as  the  old  broken  range  was  inadequate.  The 
party  of  engineers  was  landed  at  2  P.  M.,  meals 
were  served,  and  blankets,  pillows,  cots,  rubber 
bags  and  mosquito  bars  were  issued.  As  the 
bars  and  blankets  were  insufficient,  the  Commis- 
sion instructed  me  to  supply  the  deficiency  by 
purchasing  them  in  Greytown. 

Messrs.  Saabye,  Boltz,  Heyle,  Elson  and 
Snyder  were  assigned  as  assistants  for  the  Tam- 
bor  Grande  work,  and  the  party  was  designated 
as  "  No.  5."  These  men  were  employed  for 
several  days  in  the  selection  and  packing  of 
stores.  Seven  macheteros,  a  cook  and  helper 
were  selected  from  the  natives  in  town.  Pre- 
vious experience  has  decided  for  me  that  these 
men  were  far  more  efficient  and  tractable  than 
the  negroes.  On  December  27  the  river  steam- 
er "HoUenbeck"  came  to  La  Fe  at  8.30  A-  M. 
All  baggage  and  equipment  were  loaded  and  we 
started  up  the  San  Juan  river  at  9.30.  The 
steel  canoes  were  lashed  alongside.  In  ad- 
dition to  "Party  No.  5,"  the  members  of  the 
west  side  corps  and  three  observers  of  the  hydro- 
graphic  party  were  passengersj.  The  steamer 
arrived  at  Tambor  Grande  at  1  A.  M.,  December 
28.     The  supplies  were  unloaded  on  the  Costa 


Bican    side    of    the    river    opposite    Tambor 
Grande  point  during  a  severe  rainstorm,    and 
the  steamer  continued  her  trip.     An  effort  was 
made  to  spread  a  canvas  tarpaulin,  but  the  dense- 
ness  of  the  jungle  and  the  severe  rainfall   de- 
tracted much  from  the  zeal  of  the  men,  so  that 
our  shelter  was  but  a  partial  success.     At  day- 
break a  spot  was  selected  for  a  camp  a  short  dis- 
tance upstream,  where  a  partial  clearing  existed. 
The  laborers  were  instructed  to  clear  a  space  for 
the  camp  and  prepare  timbers  and  leaves   for 
shack  building.     A  kitchen  was  built  first  and 
meals  served.     The  tarpaulin  was  stretched  for 
the  officers'  quarters,  and  a  palm-leaf  shack  built 
for  the  men.     These  buildings  are  quite  inter- 
esting from  the  fact  that  no  nails  are  used,  or 
framing  done  in  any  but  the  mpst  primitive  man- 
ner.    The   jungle   furnishes   all   the   material. 
Usually  palm  leaves  are  used  in  thatching  and 
give  greater  permanency  and  a  better  water- 
proof structure  than  the  wild  plantain,  which  is 
sometimes  used  in  an  emergency.     Crotched  up- 
rights are  first  planted  firmly  in  the  ground  to 
support  the  center  ridge  pole,  and  then  for  the 
wall  plates.     Usually  the  sides  are  not  thatched 
except  in  the  more  pretentious  structures.     All 
joints  are  made  secure  with  a  liberal  use    of 
vines  ("bejuca").     Small  poles  placed  parallel 
to  the  ridge  pole  at  suitable  interval  for  the 
leaves,  usually  less  than  a  foot,  are  lashed  to 
rafters,  and  the  thatching  begins  at  the  lower 
part  of  the  roof.     Three  or  four  leaves  on  top 
of  each  other  are  placed  on  the  poles  so  that 
their  stems  catch  the  one  above  for  each  longi- 
tudinal layer.     The  layers  overlap  each  other 
like  shingles  and  make  a  covering  impervious  to 
rain  and  usually  last  with  little  repair  for  a  year 
or  more.     On  top  of  the  thatching,  breaking 
over  the  ridge,  are  placed  long  branches  of  the 
'"  Silico  "  palm  for  binding.     The  leaves  of  the 


APPENDIX  Vn.— REPORT  OF  BOYD  BHLE.  ASSISTANT  ENGINEER 


407 


wild  plantain  are  subject  to  the  ravages  of  worms 
that  destroy  them  quite  rapidly.  Our  kitchen 
was  quite  simple  in  the  furnishing:  a  ground 
fire-place  with  backlog  was  used,  with  uprights 
of  crotched  poles  and  cross  pole  for  hanging  the 
kettles.  A  "  Dutch  oven  "  was  used  for  bak- 
ing. The  officers'  beds  were  made  by  slinging 
the  hammocks  on  two  poles  and  then  supporting 
them  on  crotched  stakes  at  the  four  comers. 
Spreaders  were  necessary  at  both  ends.  The 
laborers  usually  contented  themselves  with  cut- 
ting long  slats  from  the  palms  and  making  a 
raised  cot,  or  table,  with  these  supported  on 
crotched  stakes. 

Other  necessary  work  was  the  construction  of 
walks  made  with  halved  logs,  and  the  building 
of  closets.  A  wharf  and  steps  had  to  be  built 
on  account  of  the  high  bank.  The  time  spent 
on  the  camp  was  about  one  and  a  half  days  for 
the  laborers.  The  officers  in  the  meantime  were 
employed  adjusting  instruments  and  looking  up 
points  and  bench  marks  of  the  former  surveys 
in  1888.  The  evidences  of  this  survey  were  ap- 
parently obliterated,  but  after  several  trial  lines, 
a  copper  bolt  was  found  in  a  gavilan  tree  over- 
grown with  about  nine  inches  of  wood.  This 
was  at  station  120  +  20  of  the  canal  line  located 
by  party  No.  3,  Gamett  Savage,  engineer  in 
charge  under  the  direction  of  Lieut.  R.  E.  Peary, 
sub-chief  engineer,  A.  G.  Menocal,  chief  en- 
gineer. The  elevation  of  this  B.  M.  is  104.30 
referred  to  the  Canal  Company's  datum  at  Grey- 
town,  and  is  subject  to  the  connections  obtained 
by  the  precise  levels  for  elevations  in  the  San 
Francisco  basin.  This  is  approximately  .025 
feet  plus  the  difference  of  the  two  data;  the 
Canal  Company's  and  Commission's.  The  party 
was  furnished  with  a  Brandis  transit,  5^-inch 
plate  with  a  vernier  reading  to  20  seconds,  3^- 
inch  magnetic  needle,  8-inch  telescope  with  30* 


seconds  bubble,  inverting  lenses,  and  stadia 
hairs  with  an  interval  of  1  foot  at  100  feet.  The 
graduations  of  the  circle  were  numbered  con- 
tinuously to  360  degrees  and  read  with  a  single 
vernier.  The  level  was  Brandis  make,  with  10 
seconds  bubble  and  with  stadia  hairs.  The  com- 
pass was  Gurley  make  with  5-inch  needle  and 
alidade  sights.  In  addition  to  these  there  were  a 
Philadelphia  level  rod,  hand  level,  100-ft.  chain, 
100-ft.  steel  tape,  50-ft  Chesterman  tape,  transit 
poles,  draughting  instruments,  etc.  The  instru- 
ments all  proved  of  excellent  workmanship  and 
gave  most  satisfactory  results  for  the  character 
of  work  desired.  It  was  decided  that  a  compass 
survey  with  levels  would  give  the  desired  results. 
This  survey  was  started  at  the  old  bench  mark. 
The  party  was  provisionally  organized  with  my- 
self at  compass,  Mr.  Elson  assistant,  Mr.  Saabye 
leveller,  Mr.  Boltz  rodman  and  Messrs,  Heyle 
and  Snyder  chainmen.  Five  macheteros  were 
used  with  the  compass  party  and  two  ^vith  the 
level.  This  constitutes  a  minimum  laborers' 
force  for  a  party  to  do  effective  work.  Some 
time  was  necessary  to  familiarize  both  officers 
and  laborers  with  their  new  duties.  In  general 
it  would  seem  best  to  have  experienced  men,  but 
yet  there  is  some  advantage  in  training  men  to 
one's  own  methods  if  they  are  intelligent  and 
ambitious.  The  survey  line  followed  the  crest 
of  the  ridge  to  the  San  Juan  river,  and  the  cross- 
ing was  made  by  stadia  measurement,  in  line 
with  the  nearest  buttress  hill.  This  at  first  was 
taken  above  the  point  and  the  embankment 
would  be  at  an  angle  upstream,  but  later  this 
was  changed  to  a  line  crossing  to  a  hill  below 
Tambor  Grande  point,  which  gave  better  results. 
The  survey  from  the  river  proceeded  along  a 
narrow  ridge,  very  crooked  and  broken  by  sad- 
dles. It  was  at  times  very  difficult  to  pick  out 
the  true  ridge  among  the  many  spurs.     Usually 


408 


NICARAGUA  CANAL  COMMISSION 


this  was  done  most  successfully  by  thorough 
scouting,  ahead  of  the  instrument  work.  This 
required  an  examination  of  both  sides  of  the 
ridge  and  a  careful  consideration  of  the  drain- 
age. The  latter  feature  was  verj'  confusing  in 
the  neighborhood  of  the  lagoons  and  easily  led 
to  false  conclusions.  The  tropical  jungle  is  so 
dense,  and  in  places  interlaced  with  vines  as  to 
require  the  use  of  a  machete  continuously. 

The  view  obtained  usually  does  not  extend 
beyond  the  path  cut  out.  It  had  been  suggested 
by  the  chief  engineer  that  an  effective  aid  to  a 
general  knowledge  of  the  topography  could  be 
obtained  by  observations  from  high  trees  on 
commanding  points.  Climbers  had  been  pro- 
vided, and  several  trees  were  ascended  and 
sketches  were  used  in  directing  the  survey,  but 
the  method  was  not  entirely  successful.  Usually 
the  view  was  much  obstructed,  and  inferences 
could  not  be  entirely  reliable,  as  the  peculiari- 
ties of  the  tropical  growth  almost  obliterate  dif- 
ferences of  elevations  of  fifty  feet.  It  seems 
that  in  general  the  high  trees  grow  in  the  flats 
and  the  lower  ones  on  the  hills.  There  is  great 
danger  in  climbing  trees  in  the  tropics,  especially 
in  the  rainy  season.  The  trunk  and  limbs  are 
very  slimy  and  covered  with  vines  that  must  be 
cut  away  with  a  machete.  Then  there  is  danger 
of  stings  from  the  alligator  ants  and  other  in- 
sects, and  the  bites  of  snakes  and  the  toboba 
scorpion  which  are  fatal  to  life.  The  scouting 
required  great  physical  effort  for  the  tropics, 
but,  when  well  done,  directed  the  survey  of  the 
ridge  with  great  certainty  and  with  the  least 
work  and  therefore  least  expense.  It  also  had 
the  advantage  of  actually  locating  the  necessary 
embankments.  This  work  was  usually  done  by 
the  chief  of  party  alone,  and  the  survey  directed 
by  sound  signals  without  seeing  the  party  all 
day.     It  has  been  suggested  and  tried  by  some 


engineers,  to  make  a  topographical  map  of  the 
country,  cutting  it  up  in  squares  with  survey 
lines,  and  pick  out  the  ridge  or  other  features 
desired,  and  locate  from  the  map.     This  may 
be  effective  but  only  with  great  expense  and  loss 
of  time.     In  tree  climbing  the  ordinary  line- 
man's climbers  were  used.     A  loose  rope  was 
placed  around  the  tree  and  the  body  at  the  loins; 
then  with  care  a  person  can  walk  up  the  tree 
cutting  the  vines  as  he  goes.     However,   the 
spurs  did   not  enter  the  wood  of  the  prefeiv 
able  trees  for  a  view,  as  the  almendro.     It  was 
intended  at  first  to  trace  the  embankment  line 
along  the   divide   of   Tamborcito  and   Cureiio 
creeks.     The  former  stream  had  been  unknown 
previous  to  the  survey,  and  its  large  drainage 
system  lying  across  the  desired  line  of  progress 
was  a  very  disappointing  surprise  and  furnished 
serious  features   for   the   desired   embankment 
line.     All  efforts  to  use  the  divide  of  Cureno 
and  Tamborcito  creeks  were  without  satisfactory 
results.     The  elevations  of  the  hills  are  small, 
and  the  ridge  is  often  broken  to  the  swamp  level 
by  arms  of  Tamborcito  lagoon.     Evidently,  as 
in  many  other  cases,  the  true  divide  is  the  bank 
of  the  San  Juan  river,  for  quite  a  distance  from 
Tambor  Grande.     After  recognizing  the  futility 
of  further  surveys  up  this  divide,  it  was  decided 
to  follow  the  hills  that  led  to  Tamborcito  creek 
and  cross  to  the  southern  side  which  was  unex- 
plored.    However  an  attempt  was  made  to  cross 
an  arm  of  the  lagoon  and  continue  the  survey, 
but   with   unsatisfactory   results.      A   crossing 
was  then  located  at  the  outlet  of  Tamborcito 
lagoon  and  a  revision  of  the  line  made  bade  to 
the  San  Juan  river  ending  at  the  hill  mentioned 
as  below  the  point.     This  line  had  greater  ele- 
vations, is  shorter  and  in  many  ways  more  favor- 
able than  the  first.     The  two 'ridges  are  sepa- 
rated by  a  flat  with  small  drainage.     The  San 


APPENDIX  VII.— REPORT   OF  BOYD   EHLE.  ASSISTANT   ENGINEER 


409 


Juan  river  crossing  seemed  very  favorable,  as 
soft  rock  was  in  sight  at  both  banks,  and  the  dis- 
tance less  than  any  place  on  the  river,  previously 
exploited  for  a  dam  site.  The  crossing  of  the 
valley  of  Tamborcito  creek  was  .recognized  as  a 
serious  feature,  but  was  the  only  alternative 
after  the  result  against  the  Tamborcito-Cureno 
divide.  The  hills  after  making  the  crossing 
proved  to  be  spurs  of  the  Tamborcito-Copalchi 
divide.  This  was  much  broken  by  the  prox- 
imity of  the  lagoons  of  both  these  drainage  sys- 
tems. These  lagoons  are  typical  of  the  country. 
In  the  wet  season  they  are  lakes  of  considerable 
extent,  and  boats  can  be  used,  but  as  the  dry 
season  approaches  the  navigable  channel  is  a 
mere  brook  and  is  often  clogged  by  a  rank 
growth  of  grass.  At  such  times  the  lagoons  are 
practically  impassable  for  swimming,  wading  or 
boating.  It  is  dangerous  to  attempt  the  former. 
A  mattress  of  grass  forms  below  water  level 
which  often  sustains  a  man's  weight.  The 
danger  is  in  breaking  through  into  deep  water, 
getting  tangled  in  the  grass  and  dro\vning.  The 
"  manatee  "  (sea-cow)  makes  the  grassy  banks  its 
feeding  ground  and  is  quite  abimdant.  The 
main  body  of  the  lagoon  is  usually  not  large, 
but  from  it  radiate  arms  in  all  directions.  The 
valley  floor  at  Tamborcito  creek  crossing  is  about 
3000  feet  wide.  As  the  survey  up  the  Tambor- 
cito-Copalchi divide  proceeded,  it  became  evi- 
dent that  its  use  for  an  embankment  line  at  an 
elevation  above  110  ft  would  be  of  doubtful 
value.  The  results  were  reported  to  the  first 
assistant  engineer  on  his  arrival  at  camp,  Janu- 
ary 20,  and  to  the  chief  engineer  on  his  arrival, 
January  22.  The  ridge  survey  had  progressed 
about  5i  miles,  with  the  adjacent  country  fairly 
developed  as  to  all  possibilities.  It  was  decided  to 
discontinue  the  sur\'ev,  and  instructions  were 
given  to  begin  a  sur\'ey  of  the  San  Juan  river  as 


soon  as  the  work  in  progress  could  be  closed  ad- 
vantageously. This  required  the  completion  of 
the  leveling  which  had  fallen  behind,  the  taking 
of  some  topographic  sketches,  and  the  completion 
of  maps,  profiles  and  report.  The  interval  from 
January  22  to  27  was  employed  in  this  work 
and  preparing  for  the  river  survey.  The  gen- 
eral directions  for  the  river  survey  were;  to  be- 
gin at  the  mouth  of  the  San  Francisco  and  work 
down  the  stream;  lines  of  soundings  to  be  taken 
at  about  1000  feet  or  less  interval;  the  topogra- 
phy to  be  roughly  determined  at  occasional  inter- 
vals by  paced  compass  lines,  etc.  It  was  sug- 
gested that  a  system  of  triangulation  be  used. 
As  we  had  onlv  one  20-ft.  and  one  15-ft. 
steel  canoe,  which  were  not  sufficient  for  our 
work,  it  was  decided  to  build  a  cedar  dugout.  A 
trip  to  Greytown  for  tools  and  supplies  was  nec- 
essary. This  canoe  was  made  by  the  party  at 
odd  intervals,  and  proved  very  valuable  through- 
out all  the  work.  This  kind  of  canoe  is  easily 
handled  by  the  men  and  can  be  made  very  light. 
It  cannot  replace  the  steel  canoes  for  rough  ser- 
vice and  capacity  but  is  always  obtainable.  A 
suitable  tree,  the  "  ceiba  "  or  "  cedro  real,''  is 
selected  near  the  river  bank  and  felled.  This 
is  roughly  shaped  with  axes  and  adze  according 
to  the  desired  lines,  and  dressed  to  the  required 
thickness.  The  natives  use  small  auger  holes 
to  determine  this,  and  later  plug  these  holes. 

On  January  27  the  river  triangulation  was 
started  by  measuring  a  base  line  1500  feet  long 
in  Maineri's  pasture  in  front  of  the  mouth  of  the 
Rio  San  Francisco.  The  angular  work  was 
started  from  this  and  proceeded  down  the 
stream.  It  was  early  discovered  that  the  neces- 
sary clearing  would  be  a  serious  delay  to  pro- 
gress, and  that  the  assistants  assigned  for  re- 
connaissance work  were  unfamiliar  with  the 
nicety  of  work  geodetic  in  character.     Usually 


410 


NICARAGUA   CANAL  COMMISSION 


the  transit  points  selected  were  in  soft  ground 
near  the  water  and  piles  had  to  be  used.  The 
triangles  were  usually  ill  conditioned  on  account 
of  obstructions  to  view,  and  all  angles  could  not, 
at  times,  be  measured  with  facility.  Wherever 
it  was  possible  to  check,  the  angular  error  was 
less  than  one  minute  for  the  triangles.  The 
error  in  distance  was  less  than  five  feet  as  check- 
ed by  the  stadia  after  two  miles  of  survey.  The 
soundings  were  made  on  straight  lines  across 
the  river  and  located  by  the  stadia.  A  pole  was 
used  for  soundings  up  to  15  fc^t  depth  of  water 
and  at  greater  depths,  a  lead  line.  The  station 
signals  used  were  the  ordinary  transit  poles 
guyed  in  place.  The  elevations  were  carried 
along  with  the  wye  level,  the  observer  using 
transit  and  level  alternatelv.  This  method  w-as 
adopted  as  best  fitted  to  the  organization  of  the 
party  and  its  equipment,  rather  than  the  usual 
one  of  stadia  work,  and  of  sounding  locat<?d  by 
sextant  angles.  For  the  stadia  work  Ifi-ft.  boards 
had  been  obtained  from  Greytown,  and  were 
painted  and  graduated  to  tenths  of  a  foot.  An 
observer  could  obtain  the  distance  to  the  nearest 
foot  from  these  with  great  certainty  and  facility. 
The  work  progressed  much  faster  and  the  assist- 
ants w^ere  better  acquainted  with  their  duties 
after  the  end  of  the  triangulation  near  Tambor 
Grande  point.  With  the  first  high  water  it 
was  found  that  many  transit  points  were  de- 
stroyed by  the  driftwood  and  falling  banks. 
This  gave  much  trouble,  as  these  points  were 
necessarv'  in  other  work.  The  topography  work 
was  carried  along  with  the  river  survey.  As- 
sistants were  detailed  for  the  scout  lines  about 
each  half  mile.  The  usual  procedure  was  to  go 
back  from  the  river  about  a  mile,  and  then  make 
a  look  back  to  a  lower  point  downstream  and  tie 
up  to  the  river  survey.  Tlioso  lines  weif'  ns;nally 
directed  to  develop  some  prominent  feature  of 


the   landscape,   and   were   omitted  in  the   flat, 
marshy  section. 

January  27  the  steamer  "  Hollenbeck  "  came 
down  the  river  with  the  Chicago  contractors  who 
were  studying  the  canal  route.  They  stopped 
at  our  camp  during  the  evening,  and  by  the  in- 
structions of  the  Commission,  were  allowed  the 
use  of  results  of  the  survey.  The  steamer  left 
early  the  following  morning  for  Ochoa,  where 
the  party  began  their  trip  across  country  to 
Greytown. 

Mr.  Elson  went  to  Grevtown  Februarv  6  for 
an  operation  on  his  hand,  and  returned  the  9th. 
Mr.  Saabye  was  detailed  to  report  to  Assistant 
Engineer  Walker,  February  9  by  instructions 
from  the  chief  engineer  and  left  for  Greytown 
on  the  "  Hollenbeck." 

February  16  camp  was  moved  to  a  point  on 
the  Costa  Kican  side  of  the  San  Juan  river  about 
one-quarter  mile  below  the  mouth  of  the  Rio 
Sarapiqui;  shacks  had  been  built  a  few  days 
previously.  This  location  is  the  site  of  the  old 
fort  at  which  Walker  s  filibusters  were  massacred 
by  the  Costa  Ricans.  The  mosquitoes  tried  to 
emulate  them  in  attacks  on  the  members  of  our 
party  and  their  lack  of  success  was  not  due  to 
failure  of  intent  or  energy.  The  steamer  "  Hol- 
lenbeck" came  down  at  5  P.  M.,  shortlv  after 
arrival  at  camp,  with  orders  from  the  Commis- 
sion  to  report  at  Ochoa  as  soon  as  possible  with 
all  my  laborers  to  assist  in  the  trip  across  country 
to  Greytown.  AVe  left  at  5.30  and  made  the 
twenty  miles  to  Ochoa  at  3  A.  M.  after  stopping 
at  Maineri's  to  arrange  for  men  and  provisions. 
February  16  was  spent  with  the  Commission  in 
an  examination  of  the  dam  sites  and  vicinitv  of 
Ochoa;  Preparations  were  made  for  starting 
the  next  morning.  Ten  laborers,  sent  by  Mai- 
neri  evidently  came  by  liquid  persuasion  and 
were  coiTespondingly  noisy  and  caused  consider- 


APPENDIX  VII.— REPORT  OF  BOYD  EHLE,   ASSISTANT   ENGINEER 


411 


able  trouble.  It  was  decided  to  send  all  the 
bulky  articles  by  boat  down  the  San  Juan  and 
up  the  Danta.  Our  blankets,  a  few  cooking 
utensils  and  sonio  provisions  were  made  into 
packs  of  about  60  lbs.,  for  each  laborer  early  in 
the  morning.  As  fast  as  packs  were  ready  the 
men  were  started  over  the  telegraph  picket 
which  follows  the  embankment  ridge.  Arrange- 
ments were  made,  if  necessary  to  go  but  half 
way  to  Florida  lagoon  at  Camp  Escarse,  but  on 
arrival  there  about  midday,  it  was  decided  to 
continue  our  walk  and  we  arrived  at  the  lagoon 
about  3  P.  M.,  a  distance  of  about  six  miles. 
Assistant  Engineer  Miller  and  Mr.  Lincoln,  Her- 
ald correspondent,  joined  us  in  the  afternoon. 
Mr.  O'Reardon  of  the  geological  party  acted  as 
roar  guard,  and  kept  the  straggler  with  the  packs 
moving.  Our  boats  could  not  come  up  the 
Danta  on  account  of  low  water  but  joined  us 
later  at  the  San  Francisco  crossing.  The  camps 
used  bv  the  Commission  had  been  located  at  in- 
ten^als  of  about  three  miles,  or  a  place  requiring 
difficult  engineering  constructions. 

Fel)ruars'  18  the  trip  was  made  to  the  San 
Francisco  river,  the  Commission  making  exami- 
nations of  the  various  proposed  embankments. 
Upon  our  arrival  at  3.30  P.  M.,  Assistant  Engi- 
neer F.  P.  Davis  met  us  with  his  steel  boat  and 
negro  laborers.  Mr.  Maineri  also  arrived  with 
his  boat  and  some  necessary  supplies.  Febru- 
ary 19  the  trip  was  made  to  Camp  Carmen  on 
the  Limpio,  arriving  at  10.30  A.  M.  and  it 
was  decided  to  camp  for  the  night.  This  is  at 
the  western  end  of  the  Eastern  Divide.  On  the 
20th  the  Eastern  Divide  was  inspected  and  we 
camped  at  the  Saltos  Luisa  on  the  Deseado  river. 
On  the  21st,  the  party  followed  approximately 
the  canal  line  to  Camp  Warner  ^liller,  inspect- 
ing the  dam  site  for  Lock  Xo.  3  on  the  way.  At 
the  camp  there  was  a  short  rest,  and  some  of  the 


party  walked  ahead  to  Camp  Broncho  and  took 
the  boat  that  Assistant  Engineer  Trundle 
brought  up  from  Camp  Menocal.  General 
Hains,  myself  and  three  of  my  macheteros  took 
a  boat  from  Camp  Warner  Miller  to  Menocal, 
inspecting  the  canal  location  as  it  followed  the 
general  course  of  the  stream.  The  river  was 
verv  low  and  with  manv  fallen  trees,  across 
which  the  boat  had  to  be  lifted,  but  we  made  the 
trip  in  an  hour  and  a  half  in  spite  of  all  predic- 
tions to  the  contrarv.  After  dinner,  on  the  ar- 
rival  of  the  rest  of  the  party,  the  Commissioners 
and  myself  continued  on  down  the  river  inspect- 
ing the  canal  line  and  the  sites  of  Locks  Xos. 
2  and  1.  At  the  latter  place  we  left  the  boat 
and  took  the  hand-car  to  Greytown  arriving 
there  at  6  P.  M.  Our  baggage  was  transferred 
to  La  Fe  by  boat  and  we  crossed  the  ferry  and 
went  by  car  to  headquarters  out  on  the  beach. 
The  next  two  days  were  spent  in  getting  men, 
supplies  and  rewriting  my  report  on  the  Tambor 
Grande  survey.  The  latter  was  submitted  to  the 
chief  engineer,  together  with  the  map  and  profile. 
February  24, 1  started  for  Camp  Sarapiqui,  after 
experiencing  much  difficulty  in  getting  the  men 
away  from  the  allurements  of  Greytown.  We 
met  Messrs.  Boltz  and  Elson  on  their  wav  to 
Greytown  in  a  canoe;  the  latter  had  a  badly 
swollen  knee  requiring  the  doctor's  care.  I  sent  a 
native  in  the  boat  with  him  and  took  Mr.  Boltz 
with  us.  We  stopped  at  Colorado  Junction  for 
the  night  and  got  to  camp  at  3  P.  M.  The  offi- 
cers left  at  Camp  had  not  been  able  to  accom- 
plish very  much  during  my  absence  as  no  labor- 
ers were  available.  Mondav,  February  28,  we 
continued  the  river  sun^ev  and  finished  to  the 
Cuellos  islands  at  noon,  March  5.  During  this 
time  Messrs.  Boltz,  Ileyle  and  Snyder  were  my 
only  assistants.  Mr.  Carmichael  and  Mr.  Elson 
reported  March  8  and   Mr.  Heyle  started  for 


412 


NICARAGUA  CANAL  COMMISSION 


Grevtown  on  his  wav  liome.  In  accordance 
with  instruction  the  river  survey  was  abandoned 
and  preparations  made  to  resume  the  Tambor 
Grande  embankment  survov.  To  do  tliis  re- 
quired  moving  our  camp  inland  from  the  San 
Juan  river,  and  this  could  best  be  done 
by  using  Copalchi  creek.  An  investigation 
proved  that  this  creek  was  impassable  from 
fallen  trees.  As  it  was  impossible  to  pack 
our  equipment  to  the  desired  location  it  be- 
came necessary  to  clear  the  creek.  As  this 
had  probably  never  been  done,  the  work  was 
very  difficult  and  took  the  entire  force  of  labor- 
ers a  week.  The  men  worked  in  the  water  con- 
tinually during  this  time.  Usually  all  that 
could  be  done  was  to  saw  or  cut  out  a  place  large 
enough  to  pass  the  boat.  Trees  like  the  almen- 
dro  cannot  be  cut  with  an  axe  and  here  the  saws 
issued  bv  the  'Commission  were  invaluable. 
Though  this  delay  was  much  regretted,  the  time 
was  spent  profitably  in  copying  notes,  making  a 
map  and  finishing  reconnaissance  work.  On 
April  14  we  began  moving  camp  to  the  head  of 
navigation  on  Copalchi  creek,  about  four  miles 
beyond  the  end  of  our  work.  This  moving  was 
very  difficult  as  the  creek  was  getting  lower,  and 
trees  that  had  been  made  passable  now  gave 
much  trouble.  At  places  the  boats  had  to  be 
unloaded  and  lifted  over  the  obstructions.  It 
took  three  days  of  very  exhausting  work  in  the 
water  to  get  the  camp  equipment  moved,  and  in 
tliis  officers  and  men  participated  alike.  The 
camp  on  the  Copalchi  was  very  pleasant  and  well 
located  for  our  work,  but  communication  with  it 
was  difficult.  The  wat^r  was  exceptionally  pure, 
and  fish  and  game  abundant.  March  18  we  con- 
tinued the  survey  of  the  Tamborcito-Copalchi 
divide.  At  first  this  was  somewhat  difficult  to 
trace  in  the  vicinity  of  the  lagoon,  on  account 
of    the    many    spurs    overlapping    each    other, 


and  on  account  of  the  long  narrow  branches  of 
swamp.     The  divide  was  much  broken,  but  yet 
advantageous  for  an  embankment.  By  thorough 
scouting  the  divide  was  picked  out  and  then  sur- 
veyed and  leveled  by  the  assistants.    As  we  got 
away  from  the  lagoons  the  divide  became  more 
decided  and  favorable  for  the  embankment  pro- 
ject, the  average  elevation  increased  slowly,  but 
the  breaks  in  the  hills  below  110  feet  elevation 
were  few  and  narrow.     The  distance  made  per 
day  was  8000  to  10,000  feet.     March  23,  in  an 
effort  to  do  extra  work  the  party  stayed  too  late 
in  the  field.     In  taking  a  short  cut  for  camp 
through  unknown  country  we  were  confronted 
with  impassable  swamps  and  compelled  to  wait 
until  morning.     Excepting  the  hunger  this  ex- 
perience was  not  unpleasant.     As  the  ridge  had 
not  reached  the  foot-hills  of  the  Costa  Kican 
range  when  the  walk  became  too  long,  it  be- 
came necessary  to  build  a  camp  and  pack  to  it. 
This  camp  w^as  located  at  a  bend  of  Cano  Tani- 
borcito  which  was  on  the  north  side  of  the  ridge, 
but  was  seen  first  at  this  place  since  leaving  the 
lagoon.     The  camp  was  made  for  temporary  use 
only,  and  occupied  by  the  compass  party  and 
later  by  the  level  party.     The  weather  was  be- 
coming very  dry,  and  ticks  of  various  sizes  made 
life    correspondingly   miserable    both    day   and 
night.     It  was  thought  that  the  necessary  work 
could  be  done  from  this  camp,  but  on  obtaining 
the  results  of  the  levels,  which  were  some  days 
behind,  it  was  decided  to  push  the  work  farther 
and  another  camp  was  built  at  the  end  of  the 
line.     We  used  the  camp  on  Copalchi  as  a  base 
and  packed  only  necessities  out  to  these  camj^s, 
but  the  work  was  very  arduous  for  officers  and 
laborers.     Mr.  Elson  decided  to  resign  before 
moving  to  the  last  camp  and  left  from  Copalchi 
camp  when  Mr.  Miller  came,  April  11.     Mr. 
Snyder  left  on  account  of  sickness  March  28  and 


APPENDIX  VII.— REPORT   OF  BOYD   EHLE,   ASSISTANT   ENGINEER 


413 


Mr.  Webb  reported  to  replace  him  April  6. 
April  12  the  party  finished  the  compass  work 
as  far  as  seemed  necessary  and  all  low  places  in 
the  ridge  were  cross  sectioned.  Lines  from  200 
to  300  feet  long  were  run  so  as  to  locate  the 
contours  for  an  accurate  estimate.  April  17, 
having  completed  all  work  from  camp  at  Co- 
palchi,  the  men  were  instructed  to  move  camp 
to  Tambor  Grande.  Mr.  Carmichael  and  I  went 
to  Greytown  with  a  small  canoe  and  one  native 
to  transact  certain  business  and  make  some  nec- 
essary arrangements  for  a  survey  of  a  proposed 
canal  location  along  the  left  bank  of  the  San 
Juan  river.  We  made  the  distance  to  Greytown, 
about  fifty  miles,  in  twelve  hours'  paddling.  The 
work  of  such  a  trip  is  severe,  but  the  cramped 
position  in  a  small  dug-out  in  a  boiling  sun  is 
more  trying.  On  the  27th  I  started  upstream 
in  the  small  dug-out  with  my  native  and  arrived 
at  Colorado  junction  about  6  P.  M.,  passing 
Lieut.  Hanus  and  his  party  on  their  way  to  the 
States.  At  Anderson's  we  met  the  chief  engi- 
neer and  Mr.  Carmichael,  who  had  started  the 
pre\'ious  day  and  were  waiting  for  the  river 
steamer.  The  steamer  "  Vero  "  was  lying  at  the 
junction  and  we  stayed  on  her  for  the  night. 
Finding  she  might  not  sail  for  several  days  I  left 
in  the  morning  and  got  to  Tambor  Grande  about 
5  o'clock  in  the  afternoon.  The  men  had  just 
finished  moving  camp  and  were  repairing  the 
shacks.  Mr.  Carmichael  arrived  on  the  "  Vero '' 
April  23.  On  the  25th  the  party  continued  the 
check  level  and  cross-section  work.  The  chief 
engineer  called  at  camp  on  the  27th  and  Mr. 
Carmichael  left  for  Grevtown  with  him.  The 
officers  of  the  party  were  now  reduced  to  Mr. 
Boltz  and  myself,  and  finally  he  had  to  go  ta 
Greytown  for  hospital  treatment.  May  1.  A 
large  lump  formed  under  one  arm  attended  with 
high   fever,     ilr.  Anschutz  reported  for  work 


April  30,  but  was  unacclimated  and  was  unable 
to  stand  the  long  walks  for  some  time.  Mr.  Car- 
michael and  Mr.  Thomas  reported  May  2,  and 
the  work  of  the  embankment  survey  was  fin- 
ished two  days  later.  The  party  began  the 
canal  location  indicated  on  the  map  sent  with 
the  instructions,  by  starting  at  Tambor  Grande 
and  running  northwest  along  the  left  bank  of 
the  San  Juan  river  as  far  as  the  San  Francisco 
hills.  This  was  followed  bv  another  location 
farther  in  from  the  river  bank.  The  curves  and 
tangents  were  accurately  located  on  the  ground. 
Progress  in  such  work  is  very  slow  owing  to 
the  necessity  of  directing  the  line  cutting  with 
the  transit,  and  of  cutting  or  offsetting  for  trees. 
Progress  is  also  materially  affected  by  the  length 
and  difficulties  of  the  walks.  At  first  we  had 
insufficient  men  for  both  transit  and  level  work. 
Mr.  Carmichael  went  to  Grevtown  ill  with  fever 
Mav  11.  Mr.  Thomas  and  I  were  the  only  offi- 
cers  available  for  field  w^ork.  This  made  pro- 
gress slow,  and  the  use  of  laborers  in 
responsible  positions  necessitated  continued 
watchfulness  and  was  discouraging.  Mr. 
Thomas  acted  as  transitman  and  mvself  as  chain- 
man,  axeman,  flagman,  etc.,  as  the  occasion 
required.  We  stayed  in  camp  from  May  12  to 
18,  as  we  did  not  have  enough  men  for  field 
work.  This  time  was  spent  in  copying  notes, 
making  maps  and  profiles.  May  18,  having 
hired  more  laborers,  we  resumed  the  field  work 
of  location.  On  the  23rd  Mr.  Anschutz  was 
able  to  do  field  work  and  acted  as  leveller.  Mr. 
Humphrey  and  Mr.  Durham  reported  next  day 
and  were  assigned  to  cross  section  the  survey 
line.  Mr.  Boltz  returned  from  Greytown  May 
28  anxious  to  work  but  was  not  entirely  well. 
Messrs.  Seymour  and  Post  reported  June  2  and 
were  assigned  as  leveller  and  rodman.  June  7 
we   finished   all    work    convenient    to    Tambor 


414 


NICARAGUA  CANAL  COMMISSION 


Grande  and  moved  to  Sarapiqui.  Our  old  camp 
was  remodeled  to  consist  of  two  large  shacks,  a 
cook  shack  and  tarpaulin  tent.  The  location 
survey  was  continued,  and  it  was  noticed  not  to 
fit  the  ground  very  well  and  was  departing 
gradually  from  the  desired  topography.  June 
11  men  were  sent  to  begin  camp  building  at 
Punta  Petaca  at  San  Juanillo  junction  on  the 
Nicaragua  side.  Mr.  Hughes  and  Mr.  A.  P. 
Davis  called  on  their  way  to  Grey  town  and 
stopped  over  night.  June  19  the  steamer 
"  Adele  "  came  down  with  laborers  that  were 
much  needed  by  the  engineer  parties.  The  re- 
cruiting of  men  for  the  war  had  taken  all  avail- 
able laborers  from  our  vicinitv.  The  few  men 
we  had  were  in  constant  fear  of  conscription  and 
could  not  be  persuaded  to  go  out  to  the  steamers 
when  soldiers  were  aboard.  This  accounted  for 
building  our  camps  on  the  Costa  Rican  side  of 
the  river  previous  to  the  ending  of  the  war.  June 
21  we  moved  camp  to  Punta  Petaca.  The  sur- 
vey work  done  from  this  camp  was  very  disa- 
greeable and  difficult  to  get  at.  The  line  fol- 
lows the  general  direction  of  the  Rio  Xegro  val- 
ley, and  this  has  many  difficult  lagoon  and 
stream  crossings.  The  walks  to  and  from  work 
were  very  long  and  exhausting.  Usually  the 
line  was  run  ahead  a  half  or  three-quarters  of  a 
mile  each  day,  and  at  evening  a  trail  was  cut 
direct  to  the  river.  The  floods  in  the  valley 
made  swimming  necessary,  this  was  at  times  dan- 
gerous. Several  men  were  swept  away  and  only 
rescued  with  great  efforts  by  the  better  swim- 
mers. The  results  of  the  surv^ev  showed  the  line 
was  becoming  undesirable  for  a  canal  location, 
although  continued  as  indicated  on  the  map  until 
July  2,  when  it  seemed  best  to  discontinue  the 
survey  until  further  instructions.  This  was  re- 
ported to  the  chief  engineer  July  3;  it  was 
decided  to  follow  the  desired  line  on  the  ground 


as  closely  as  possible  with  a  random  transit  line. 
A    width    of    topography    of    600    feet    was 
taken  on  the  line  run,  and  fitted  the  old  work 
very  well.     The  surveys  of  the  Rio  Negro  sec- 
tion made  by  the  Canal  Company  were  very 
complete  in  detail  and  reliable.      Our  survey 
from  the  Rio  Negro  crossing,  followed  the  left 
bank  of  the  San  Juanillo  to  the  mouth  of  the 
Hio  Pescado.     Mr.  Anschutz  resigned  July  4 
and   Mr.    Thomas  was   detailed   to   assist  Mr. 
Evans.     Mr.  Post  was  made  leveller  while  Mr. 
Seymour  assisted  the  transit  party.     Mr.  Hum- 
phrey acted  as  transitman  from  the  Rio  Negro 
to  Greytown.     July  14  we  moved  to  a  camp 
built  at  the  Rio  Pescado.     The  line  leaves  the 
San  Juanillo  at  this  point  and  cuts  across  a  small 
divide  to  the  Rio  Misterioso  and  follows  the 
right  bank  of  this  stream.     July  20  we  built  a 
new  camp  on  the  Misterioso  at  the  head  of  the 
lagoon.     The  transit  party  moved  to  this  camp, 
packing  such  things  as  were  absolutely  neces- 
sary.    The   level   party   continued   their  work 
from  the  old  camp.     Wlien  the  line  reached 
Misterioso  lagoon  it  was  impossible  to  cross  with- 
out boats.     As  the  point  of  outlet  of  the  Mis- 
terioso was  unknown,  we  built  a  canvas  boat  and 
Mr.  Seymour  and  one  man  made  the  trip  to  the 
San  Juanillo,  while  Mr.  Durham  and  I  took  the 
camp  equipments  around  the  San  Juanillo  and 
met  them.     The  country  here  is  one  vast  swamp 
at  ordinary  stages  of  the  water  and  the  course 
of  the  Misterioso  was  very  difficult  to  follow. 
A  camping  ground  had  been  selected  and  our 
loaded  boats  were  sent  to  this  site.     Mr.  Sey- 
mour and  I  went  to  Greytown  for  supplies  and 
were  picked  up  by  the  steamer  "Miria"  com- 
ing out  of  Silico  lake.     The  Misterioso  enters 
the  Rio  San  Juanillo  about  three-quarters  of  a 
mile  above  the  outlet  of  Silico  lake,  but  cannot 
be  easily  found.     As  our  canvas  boat  had  proved 


APPENDIX  VII.— REPORT   OF  BOYD   EHLE,   ASSISTANT   ENGINEER 


415 


very  useful  for  the  swamp  work  it  was  decided 
to  build  another  better  one,  and  material  was  pro- 
cured. The  steamer  **Miria"  took  ourselves 
and  supplies  as  far  as  Cano  Profundo,  and  we 
paddled  up  the  Misterioso  to  the  camp  built  by 
Mr*  Durham.  The  next  morning  we  continued 
the  transit  survey  after  taking  provisions  to  the 
level  party.  The  line  took  us  through  the  cen- 
ter of  Misterioso  lagoon  and  then  cut  across  a 
long  bend  of  the  stream  along  a  line  of  small 
hills.  From  the  last  crossing  of  the  Misterioso 
to  the  San  Juanillo  crossing  there  is  a  swampy 
flat  with  a  depth  of  water  up  to  six  feet,  chang- 
ing with  the  floods  in  the  river,  which  has  no 
well-defined  banks.  After  the  San  Juanillo 
crossing,  it  becomes  necessary  to  make  a  junc- 
tion with  the  end  of  Martinez's  survey,  and  I 
went  to  Greytown  and  cut  out  his  line  produced, 
while  the  rest  of  the  party  continued  the  survey. 
We  used  our  firearms  for  signalling,  and  effected 
a  junction  thereby  without  any  loss  of  distance. 
The  country  back  of  Greytown  is  one  big  swamp 
grown  up  with  tres,  and  had  depths  of  water 
up  to  eight  feet.  As  the  rains  were  quite  se- 
vere it  was  difficult  to  determine  where  the 
water  level  was  with  regard  to  ourselves.  We 
finished  the  transit  work  August  4  and  the  level 
party  came  in  four  days  later.  The  party  dis- 
banded as  it  came  in,  all  equipment  was  turned 
over  to  the  commissary  and  the  laborers  were 
paid  off.  ^Messrs.  Humphrey  and  Durham 
checked  and  copied  the  transit  notes  and  assisted 
with  the  map.  Messrs.  Post  and  Boltz  checked 
and  copied  the  level  notes.  This  work  was  fin- 
ished August  15,  except  inking  the  map,  for 
which  Mr.  Durham  was  retained,  and  the  other 
officers  we're  given  assignments  by  the  chief  engi- 
neer. I  was  instructed  to  report  to  the  President 
of  the  Commission  in  Washington,  and  left 
Greytown  August  19  on  the  Atlas  steamer,  arriv- 


ing at  New  York  August  29.  The  chief  engi- 
neer assigned  me  office  work  for  the  estimate 
and  report  of  the  Tambor  Grande  embank- 
ment line.  Admiral  Walker  sent  me  to  New 
York  city  October  12  to  collect  and  ship  all 
Maritime  Company's  data.  This  was  completed 
October  25,  and  on  my  return  to  Washington 
the  Tambor  Grande  estimate  was  abandoned,  and 
an  estimate  of  the  San  Juan  river  section  made 
for  several  variants.  Other  work  up  to  the 
present  time  has  been  an  estimate  and  report  for 
the  Maritime  Canal  Company's  project  with  the 
Commission's  revised  data,  a  revised  estimate  of 
the  Commission's  Menocal  route  project,  a 
report  and  estimate  on  the  Ochoa  dam  and  its 
construction,  an  estimate  and  report  on  a  lock, 
15.8  foot  lift,  etc.  All  of  which  work  has  been 
submitted,  together  with  maps,  note  books  and 
data  of  all  field  work. 

The  Tambor  Grande  Survey. 

The  information  that  suggested  this  survey 
was  the  result  of  a  reconnaissance  in  the  year 
1893,  made  when  assistant  engineer  for  the 
Nicaragua  Canal  Construction  Company.  It 
was  thought  that  all  possibilities  for  an  embank- 
ment across  the  San  Juan  valley  had  been  ex- 
hausted, but  the  results  obtained  seemed  to  indi- 
cate that  the  investigation  at  this  point  might  not 
have  been  thorough.  With  a  high-level  project, 
using  the  location  across  the  Eastern  Divide,  an 
embankment  line  below  the  mouth  of  the  Rio 
San  Francisco  is  most  desirable,  as  eliminating 
an  embankment  line  roughly  parallel  to  the 
river  for  over  fourteen  miles.  Many  of  these 
embankments  were  manifestly  difficult  of  con- 
struction. It  seemed  that  an  embankment  cross- 
ing the  valley  at  right  angles  should  give 
the  best  results.  Also  the  material  from  the 
divide    cut    would    be    available    at    Tambor 


416 


NICARAGUA  CANAL  COMMISSION 


Grande  with  least  work,  this  would  aid  greatly 
in  time  and  cost.  The  cost  of  a  canal 
could  be  materially  decreased  by  bringing  the 
location  down  the  valley  of  the  Chanchos,  after 
leaving  the  divide.  These  items,  which  might 
decrease  greatly  the  cost,  facilitate  the  construc- 
tion, and  affect  the  permanency  of  a  canal  were 
the  incentives  for  an  investigation.  It  was  at 
once  evident  on  examination  that  an  embank- 
ment line  at  three  of  the  spurs  from  the  divide, 
Tamborcito,  Sarapiqui  and  San  Francisco  would 
be  apparently  out  of  the  question,  as  no  continu- 
ous hills  existed  in  Costa  Rica.  At  Tambor 
Grande  the  spur  comes  down  to  the  river  on  the 
Nicaragua  side  with  no  embankments  for  the 
highest  proposed  elevation  of  the  summit  level. 
The  developments  of  the  survey  in  Costa  Rica 
would  seem  to  indicate  that  a  summit  level  110 
feet  would  be  too  great  for  the  topographical  con- 
ditions. All  hopes  as  to  the  usefulness  of  the 
Cureno-Tamborcito  divide  were  quickly  dis- 
pelled. The  only  apparent  alternative  was  to 
cross  the  Tamborcito  and  take  the  divide  be- 
tween it  and  the  Copalchi.  This  crossing 
proved  a  most  serious  feature  for  the  project. 
The  divide  after  this  crossing,  is  apparently  use- 
ful for  an  embankment.  The  geological  data 
as  developed  by  borings  show  the  soil  overlying 
the  rock  to  be  clay.  The  rock  in  the  hills  is  of 
two  general  classes  according  to  the  hardness,  as 
found  in  nearly  all  investigations  in  this  section. 
There  is  the  hard  rock  in  place  of  volcanic  ori- 
gin, and  overlying  this  is  the  softer  rock.  The 
rock  in  the  buttressing  hills  at  Tambor  Grande, 
evident  to  the  observer,  is  the  softer  class.  This 
would  offer  good  facilities  for  the  dam  construc- 
tion, wore  it  not  for  the  fact  that  it  is  eroded  to 
a  depth  that  would  seem  inadvisable  for  dam 
conj^.truction,  imless  we  admit  the  permanency 
of  rock-fill   construction  for  such   cases.     This 


would  solve  the  difficulties  at  both  the  river  and 
lagoon  crossing,  and  the  entire  prism  of  excava- 
tion of  the  divide  cut  could  be  used  for  this 
purpose.  As  a  masonry  construction  the  Croton 
Aqueduct  dam  has  about  the  same  height,  but 
the  volume  of  water  to  be  controlled  during  the 
construction  is  insignificant  compared  with  the 
floods  of  the  San  Juan  river.     It  might  be  pes- 

• 

sible  to  divert  the  San  Juan  and  build  the  dam, 
but  it  would  scarcelv  seem  advisable  unless  it 
was  an  onlv  resort  It  is  evident  from  the  re- 
suits  obtained  showing  the  rock  erosion  in  the  old 
river  bed,  that  any  dam  project  below  the  mouth 
of  the  San  Carlos  would  be  extremely  hazardous. 
Had  this  knowledge  of  the  old  river  been  avail- 
able, it  would  have  obviated  the  necessity  for  a 
survey.  Another  decisive  feature  developed  by 
the  Commission  is  the  danger  from  the  immens^ 
sand  deposits  brought  down  by  the  Rio  San 
Carlos.  This  is  a  serious  danger  to  any  basin 
project  below  its  mouth.  The  length  of  a  crest 
line  for  the  embankments  at  118  feet  level  would 
be  about  8.2  miles.  Many  of  these  are  small, 
as  the  water  line,  110  feet  level,  is  but  5.6  miles. 
With  an  embankment  crest  at  98  feet  and  water 
level  at  90  feet,  the  crest  line  would  be  3.33 
miles  and  flowage  2.22  miles^  This  is  the 
scheme  that  would  be  most  favorable,  having  a 
lock  at  Machuca  and  making  about  20  feet 
deeper  cut  at  the  Divide.  It  can  perhaps  be 
utilized  best  with  a  dam  above  the  Rio  San 
Carlos,  thus  avoiding  the  sand  flow. 

San  Juan  River  Survey. 

As  stated  above,  it  is  doubtful  if,  it  is  expe- 
dient to  canalize  the  river  below  Boca  San  Car- 
los  on  account  of  the  sand,  the  difficult  founda- 
tions for  the  dams  and  the  great  volume  of  water 
to  be  controlled  during  the  construction  and 
operation  of  the  canal.     These  items  would  seem 


APPENDIX  VII.— REPORT   OF  BOYD   EHLE,   ASSISTANT   ENGINEER 


417 


to  render  doubtful  the  feasibility  and  perma- 
nency of  projects  involving  them. 

The  Lull  Route,  Vaeiaxt  I,  Survey. 

This  survey  followed  the  left  bank  of  the  San 
Juan  river  from  the  San  Francisco  to  Tambor- 
cito,  and  then  through  the  valley  of  the  Rio 
Negro  to  the  San  Juanillo,  and  down  the  gen- 
eral course  of  this  stream  in  an  almost  straight 
line  to  Greytown,  passing  north  of  the  hills 
around  Silico  lake.  The  survev  location  cut 
through  the  spurs  at  Tambor  Grande,  Tambor- 
cito  and  Sarapiqui  in  a  direct  line.  This  align- 
ment is  at  the  cost  of  extra  work  that  can  be  par- 
tially avoided  by  more  cun^es,  bringing  the  line 
nearer  the  river  bank. 

The  drainage  systems  on  this  side  of  the  river 
are  small  and  can  be  easily  taken  care  of  by 
weirs.  The  streams  carry  little  detritus  and 
could  be  taken  into  the  canal  with  small  expense 
for  dredging  during  operation,  but  it  would  be 
possible  to  use  invert  siphons  under  the  canal 
entirely  doing  away  with  this  difficulty.  These 
constructions  are  troublesome  to  keep  clean. 
It  will  be  necessarj^  to  carefully  provide  for  the 
action  of  the  great  floods  which  in  this  sec- 
tion have  a  wide  range  and  overflow  the  flats 
in  the  Rio  Negro  valley  about  eight  feet,  at  the 
extreme  high  water.  The  material  in  the  hills 
is  generally  red  clay  overlying  a  rock  core.  The 
flats  are  of  alluvium  overlying  clay,  excepting 
in  the  delta  formation  which  is  built  almost 
entirely  of  black  sand. 

The  line  north  of  Silico  lake  offers  good  topo- 
graphical and  geological  features  for  the  canal 
and  its  locks.  The  excavation  can  be  done  with 
great  facility  by  dredging  except  in  the  large 
hilk 

Lock  sites  can  be  so  selected  as  to  have  rock 
foundations.  It  seems  probable  that  this  line 
27 


would  give  a  short  line  to  Greytown  with  least 
cost,  and  of  assured  permanency.  All  drainage 
below  the  Rio  Xegro  can  be  shut  out  of  the  canal 
by  diversions  channels  and  dams. 

If  it  is  considered  best  to  locate  a  harbor  near 
Rio  Indio,  in  order  to  avoid  the  sand  from  the 
Rio  Colorado  as  much  as  possible,  this  location 
would  be  most  available  for  a  low-level  project. 

Regarding  the  character  of  the  survey  work 
it  was  found,  that  in  a  loop  of  the  canal  location 

and  river  survev  from  the  Rio  San  Francisco  to 

I' 

Tamborcito,  a  circuit  of  about  eight  miles,  the 
closure  error  was  about  thirty  feet.  In  plotting 
our  location  in  connection  with  the  Lull  survev 
the  results  at  Greytown  checked  with  great 
nicety. 

The  facilities  of  transportation  are  very  lim- 
ited. The  rivers  are  usually  in  a  chronic  state 
of  low  water,  or  are  clogged  with  trees.  During 
the  work  of  the  Canal  Company,  snag  boats  were 
used  in  the  Rio  Deseado,  San  Francisco,  Danta, 
San  Juanillo  and  others.  TJsuallv  a  twentv- 
foot  canoe  is  the  largest  craft  that  can  be  used 
on  these  streams  for  transportation.  The  rail- 
way as  constructed  was  invaluable  and  is  a  neces- 
sary adjunct  of  canal  construction.  The 
country  offers  very  little  for  construction  work. 
Quarries  are  as  yet  undeveloped.  Good  stone  is 
very  scarce.  Usually  soft  rock  overlies  the  bet- 
ter grades  for  considerable  depth  so  that  they 
are  not  easilv  available.  If  the  Eastern  Divide 
cut  is  made,  its  material  would  be  useful,  other- 
wise rock  must  be  quarried  for  lock  masonrj', 
etc.  For  this  the  sandstone  at  Machuca  seems 
most  available  and  it  can  be  obtained  in  large 
blocks.  Stone  of  a  better  grade  can  be  obtained 
from  the  west  side  of  the  lake  where  good  quar- 
ries exist. 

Timber  for  constmction  has  been  undevel- 
oped.    The  forests  are  not  deciduous,  and  the 


418 


NICARAGUA  CANAL  COMMISSION 


trees  have  much  sap  that  causes  rapid  decay.  It 
seems  that  the  flow  of  sap  is  affected  by  phases 
of  the  moon  and  this  has  a  great  influence  on 
their  decay.  The  natives  recognize  this  and  cut 
their  trees  accordingly.  The  better  grades  of 
timber  when  seasoned  give  good  results..  The 
timber  should  be  felled  or  girdled  when  the  least 
sap  is  in  the  trunks.  A  strange  feature  of  the 
tropical  forest  is  that  trees  of  all  kinds  grow 
together  promiscuously.  There  are  no  forests  of 
any  one  kind  like  our  pine  woods.  Trees  like 
the  mahogany  are  scattered  often  at  a  mile  or 
more  apart. 

For  railway  construction  the  cutarro  and 
nispero  give  good  results  for  ties.  Many  trees 
would  give  good  results  in  foundations  and  some 
in  superstructure.  Of  the  latter  are  the  cedars, 
man  wood,  nispero,  blackwood,  etc.,  which  are 
fairly  abimdant  The  Cuban  pine  growing  in 
the  Prinzapolka  district  gives  good  lumber. 
There  are  no  sawmills  in  the  San  Juan  valley 
at  present,  and  timber  is  difficult  to  get  at,  except 
near  the  river  banks.  No  doubt  lumbermen 
could  readily  overcome  this  difficulty.  The 
white  ants  honeycomb  and  destroy  timber  very 
rapidly.  Some  timber  is  not  affected  by  these 
.pests;  such  as  the  cedro  real.  Ties  of  good  na- 
tive wood,  as  the  nispero,  last  from  one  to  three 
years  and  cost  about  fifty  cents  silver.  Lignum 
vitsB  ties  may  last,  as  at  Panama,  15  to  30  years, 
but  cost  much  more  and  are  difficult  to  obtain. 

Regarding  the  health  of  the  party,  due  allow- 
ance must  be  made  for  the  fact  that  we  were 
employed  the  entire  time  in  the  worst  section  of 
Nicaragua  and  engaged  on  work  that  was  most 
4ifficult  of  attack.  The  number  of  officers  that 
became  ill  was  perhaps  greater  than  in  any  other 
party,  due  to  this  fact.  The  survey  was  pushed 
and  the  men  wore  out  unless  inured  to  work  and 


hardships.  It  is  true  that  the  influence  of  life  in 
the  swamps  for  so  long  a  period  produced  its 
effects,  yet  one  laborer  and  myself  passed 
through  it  all  ^\'ithout  the  slightest  sickness,  or 
missing  a  single  day's  work. 

Immaturity  has  a  great  influence  on  men,  and 
it  was  a  rule  with  the  Canal  Company's  surgeons, 
that  no  one  under  21  years  of  age  was  con- 
sidered a  proper  person  for  exposure  to  the  en- 
ervating effect  of  the  tropics.  The  party  was 
almost  entirely  supplied  by  the  rations  issued 
by  the  commissary,  which  were  very  satisfactory. 
These  were  supplemented  by  plantains,  game 
and  fish.  It  was  found  necessary  to  decrease 
the  allowance  of  meat  and  almost  dispense  with 
its  use  for  officers  and  laborers  alike.  In  place 
of  meat  an  extra  allowance  of  rice  and  beans 
was  used.  These  with  plantains  should  form 
the  bulk  of  rations  in  the  tropics.  The  observa- 
tions of  nearly  five  years  in  these  swamp  surveys 
would  seem  to  indicate  that  liquor,  properly 
used  at  times  of  great  physical  depression,  is  a 
restorative  of  great  value,  while  the  abuse  of  it 
is  attended  with  worse  effects  and  more  imme- 
diate than  in  the  temperate  zone. 

Much  credit  is  due  to  the  officers  and  laborers 
alike  for  the  successful  prosecution  of  the  work, 
exposed  to  great  hardships  and  very  trying  diffi- 
culties. Eacli  gave  his  efforts  as  he  could  and 
contributed  to  the  work  accomplished,  which  it 
is  hoped  may  meet  with  your  commendation  and 
be  an  aid  to  the  greatest  engineering  scheme  of 
this  century,  an  Isthmian  Canal. 

In  conclusion  I  wish  to  acknowledge  my  in- 
debtedness to  my  associates  for  the  measure  of 
success  attained,  and  for  favorably  seconding  my 
efforts;  particularly  is  mention  due  to  Messrs. 
Carmichael,  Thomas,  Post,  Boltz,  Humphrey 
and  Durham  for  ability  and  faithfulness. 


APPENDIX  VIII 


REPORT  OF  S.  S.  EVANS 


Assistant  Engineer 


■  I 


CONTENTS 

PAGE 

Itinerary 423 

Low  Level  Line  South  of  Lake  Silico 423 

Physical  Features 424 

Cost  of  Earth  Excavation 425 

Vegetation    425 

Health  of  Party 425 

Greytown  Headquarters 425 

Boca  San  Carlos  Survey 426 

The  Labor  Question  and  Effects  of  the  Climate  of  Nicaragua 427 

Aid  to  be  Derived  from  the  Resources  of  Nicaragua   428 

Timber  Supply 428 

Native  Food  Supply 428 

Native  Labor  Supply 429 

Boca  San  Carlos  Dam 429 

Estimate  for  Boca  San  Carlos  Dam  and  Waste-Weir 430 


APPENDIX  VIII 


Washington,  D.  C,  April  15,  1898. 
Mb.  E.  S.  Wheelee,  Chief  Engineer,  Nicaragua 
Canal  Commission. 

Sir: — I  joined  the  expedition  for  Nicaragua 
in  New  York,  on  December  4,  1897,  leaving  on 
the  next  day  on  the  "  Newport "  for  Greytown. 
On  arriving  there,  December  17,  I  was  assigned 
as  assistant  to  Mr.  George  W.  Brown  on  the 
survey  of  the  Rio  San  Juan,  and  on  the  measure- 
ment of  a  base  line  at  Fort  San  Carlos  for  use 
in  the  triangulation  of  Lake  Nicaragua.  Mr. 
Brown,  being  shortly  recalled  to  the  States,  was 
replaced  by  Mr.  Francis  Lee  Stuart,  with  whom 
I  remained  until  Julv  3,  1898,  the  sur\'ev  of  the 
San  Juan  being  by  this  time  nearly  completed. 
On  July  1,  I  received  orders  to  report  at  Grey- 
town  for  other  duties,  and  on  arriving  there 
July  3,  was  assigned  to  take  charge  of  a  party 
then  engaged  in  measuring  a  proposed  low-level 
line  from  Harbor  Head  to  a  point  near  Punta 
Petaca,  passing  south  of  Lake  Silico.  This  work 
was  completed  August  26,  and  I  received  orders 
to  report  at  Washington  in  company  with  others 
who  were  to  leave  Greytown  September  2;  but 
on  August  31  instructions  came  from  the  Presi- 
dent of  the  Commission  requiring  the  presence 
of  Mr.  H.  C.  Miller,  the  first  assistant  engineer, 
in  Washington,  and  detailing  me  to  remain  in 
Greytown  acting  in  his  place.  On  September 
27  Mr.  A.  P.  Davis  sailed  for  Washington,  leav- 
ing me  in  general  charge  of  the  hydrographic 
work.     On  December  19  I  received  orders  to 


make  an  investigation  •of  a  proposed  dam  site 
above  the  mouth  of  the  San  Carlos  river  and 
to  take  the  topography  on  the  north  side  of  the 
San  Juan  from  the  San  Carlos  to  a  point  one 
mile  below  the  Machado  creek.  This  I  com- 
pleted February  4,  1899,  and  returned  to  Grey- 
town. After  storing  the  remaining  property 
of  the  Commission  in  one  of  the  Maritime  Canal 
Company's  buildings  at  La  Fe,  and  leaving  Mr. 
11.  C.  Hurd  in  charge  of  the  hydrographic  parties 
still  in  the  field,  I  took  passage  on  the  Atlas 
steamer  "  Alene,"  on  February  18  and  reported 
at  the  office  of  the  Commission  at  Washington 
on  March  6,  1899. 

I  beg  to  submit  the  following  more  detailed 
report  of  my  work  and  experiences  in  Nicaragua 
while  in  the  service  of  the  Commission,  begin- 
ning with  the  date  July  4,  1898,  when  I  took 
charge  of  the  party  surveying  the  low-level  line 
south  of  Lake  Silico.  My  work  previous  to  that 
time  is  covered  by  the  report  of  Mr.  Francis  Lee 
Stuart. 

On  arrival  at  the  encampment  of  the  party  on 
a  small  hill  near  Lake  Silico,  I  found  that  the 
line  had  already  been  run  to  station  109-|-96.6 
on  the  south  bank  of  the  river  San  Juanillo,  as 
shown  by  the  accompanying  map.  I  found  also 
that  the  San  Juan  river  had  recently  risen  and 
overflowed  the  swamps  through  which  the  line 
runs  to  an  average  depth  of  from  four  to  five 
feet.  As  it  is  impossible  to  work  in  this  depth 
of  water  on  foot,  especially  as  there  were  fre- 


424 


NICARAGUA   CANAL  COMMISSION 


quent  lioles  in  which  the  water  and  mud  were 
several  feet  deeper,  it  was  necessary  to  do  all 
the  work  from  boats.  The  instrument  could  not 
be  set  up  on  its  tripod  and  resort  was  had  to 
driving  a  long  pile  in  the  mud  in  the  place  of 
the  ordinary  transit  hub.  This  was  made  firm 
by  braces,  its  top  cut  off  square  and  a  board 
nailed  thereon.  Into  the  board  the  center  tack 
was  driven,  over  whiclr  the  trivet  of  the  instru- 
ment was  centered  and  nailed  fast.  The  instru- 
ment was  tlien  screwed  to  the  trivet  and  the  line 
carried  forward  as  ordinarilv.  The  distances 
were  obtained  by  stadia  readings.  In  this  man- 
ner an  average  distance  of  about  one-quarter 
mile  per  day  was  covered  for  about  three  miles, 
when  the  ground  becoming  higher  and  the  water 
having  fallen  to  some  extent,  we  managed  to 
push  ahead  without  the  use  of  the  boats.  At 
station  377  we  reached  the  first  of  the  hills 
which  surround  Lake  Silico.  From  here  the 
line  ran  over  a  succession  of  steep  hills  and 
swampy  flats.  The  flats  are  all  at  the  level  of 
the  fan-shaped  delta  plain  which  slopes  gradually 
toward  the  coast,  and  the  hills  have  the  appear- 
ance of  being  thrust  up  through  it,  or  of  having 
settled  down,  the  plain  having  been  afterward 
formed  around  them  by  deposition  from  water. 
The  principal  body  of  the  hills  crossed  is  be- 
tween station  386  and  station  572,  making  about 
3.5  miles  of  hills,  the  maximum  height  of  which 
is  170  feet  above  sea  level.  From  station  572 
to  the  end  of  the  line  opposite  the  upper  end  of 
the  San  Juanillo  river  the  swampy  delta  plain 
is  again  traversed,  being  broken  by  occasional 
small  hills.  After  crossing  the  San  Juanillo  the 
survey  w^as  connected  to  station  18  of  the  river 
work  by  a  compass  line  5400  feet  long. 

The  Caribbean  and  Pacific  Transit  Company 
are  building  a  line  of  railway  from  the  head  of 
Lake  Silico  to  a  point  on  the  San  Juan  river. 


We  crossed  this  line  at  three  points,  stations 
511-f  74,  520-f  54,  and  563-f  35,  respectively. 
The  construction  of  this  road  has  necessitated 
the  excavation  of  several  cuts  through  the  hills, 
one  of  which  is  40  feet  deep.  At  these  cuts 
some  observations  can  be  made  on  the  character 
of  the  interior  of  the  hills,  and  from  the  experi- 
ence of  tlie  Transit  Company,  some  conclusions 
can  be  arrived  at  as  to  the  difficulties  and  cost 
of  doing  earthwork  in  this  locality.   . 

Physical  Features. — The  line  runs  for  prac- 
tically its  whole  length  through  the  delta  plain 
of  the  San  Juan  river,  the  original  topography 
of  which  is  covered  over  by  the  deposits  of  the 
river,  ^vith  the  exception  of  the  hills  still  pro- 
jecting up  through  it.  The  plain  is  intersected 
by  several  open  spaces  of  water  or  lagoons  and 
numerous  watercourses,  the  principal  of  which 
is  the  San  Juanillo  river  which  leaves  the  San 
Juan  river  through  a  small  channel  a  short  dis- 
tance below  Punta  Petaca  and  gathering  nu- 
merous tributaries,  the  principal  of  which  are 
the  Rio  Deseado,  Rio  Misterioso  and  Cano  Pro- 
fundo,  by  which  it  is  swelled  into  a  considerable 
stream,  again  enters  the  San  Juan  about  two 
miles  from  Greytown.  Lake  Silico  is  a  pictur- 
esque body  of  water  about  one  and  a  quarter 
miles  long  and  three-quarters  wide,  set  in  among 
the  hills  and  having  the  appearance  of  being  a 
true  lake  and  not  a  lagoon.  It  discharges  into 
the  San  Juanillo  by  means  of  the  Cano  Profun- 
do.  The  swamps  of  the  delta  plain  are  covered 
with  a  deposit  more  or  less  thick  of  loose  vege- 
table matter  fallen  from  trees,  palms,  etc.,  to 
which  more  or  less  consistency  is  given  by  matted 
roots.  In  walking  over  it  there  is  constant  lia- 
bility of  stepping  into  a  soft  place  and  sinking 
up  to  the  waist  or  possibly  over  the  head. 

The  topography  of  the  hill  section  is  very 
much  broken.     The  hills  are  composed  on  the 


APPENDIX  VIII.— REPORT   OF   S.   S.   EVANS,   ASSISTANT   ENGINEER 


425 


surface  of  clay,  weathered  from  volcanic  rock 
which  is  probably,  as  found  elsewhere  in  simUar 
hills,  from  50  to  80  feet  below  the  surface.  The 
railroad  cuts  did  not  show  any  solid  ledge  of 
rock,  but  the  ground  was  full  of  large  boulders 
which  were  broken  up  by  blasting. 

Cost  of  Eabth  Excavation. — The  cost  of 
moving  the  earth  in  the  railroad  cuts  was  stated 
to  me  by  Mr.'  Shardsmith,  the  engineer  in 
charge,  as  between  forty  and  fifty  cents  per 
cubic  yard.  None  of  it  was  moved  more  than 
about  300  feet.  The  method  of  doing  the  work 
was  primitive,  it  not  being  of  sufficient  magni- 
tude to  warrant  the  importation  of  the  proper 
tools.  The  only  means  of  transporting  the  ex- 
cavated earth  was  by  wheelbarrows,  and  in  case 
of  one  of  the  cuts,  by  two  or  three  small  dump 
cars,  only  one  of  which  could  be  filled  at  once. 
The  earth  was  loosened  by  picks  and  by  powder 
blasts.  At  the  time  I  saw  it,  it  was  the  worst 
of  the  rainy  season,  and  the  whole  place  was 
one  grand  mud-puddle  which  of  course  added  to 
the  cost.  The  labor  employed  consisted  princi- 
pally of  negroes  from  the  Fortune  islands,  to- 
gether with  some  native  Xicaraguans.  There 
did  not  appear  to  be  any  more  sickness  among 
them  than  would  be  expected  in  a  similar  gang 
in  the  United  States. 

Vegetation. — The  most  characteristic  vege- 
table growth  of  the  delta  plain,  and  of  all 
swamps  in  the  region  of  the  San  Juan  whose 
elevation  does  not  exceed  about  two  feet  below 
the  maximum  flood-plane,  is  the  Uolio  palm. 
The  presence  of  the  palm  is  a  sure  indication  of 
swamps  of  this  character.  They  are  called  by 
the  Americans  "Silico  swamps."  In  parts 
where  the  ground  is  high  enough  to  be  only  oc- 
casionally submerged  there  is  a  timber  growth, 
the  most  useful  tree  perhaps  being  the  gavilan 
or  wild  tamarind.     It  furnished  a  hard  and  very 


durable  wood,  suitable  for  railroad  cross-ties  and 
similar  purposes.  Among  the  hills  there  are 
several  varieties  of  trees  whose  wood  is  valuable. 
Some  of  these  woods,  according  to  the  testimony 
of  the  natives,  seem  to  resist  natural  decay  al- 
most indefinitely  and  for  strength  and  durability 
are  far  superior  to  any  that  could  be  imported 
from  the  States.  With  the  opportunities  and 
sources  of  information  that  we  had  while  living 
in  camp,  and  with  the  limited  time  available  for 
making  observations  on  these  woods  it  was  im- 
possible to  get  together  anything  like  precise 
data.  Such  information  as  could  be  obtained 
from  the  native  workmen  with  us,  either  as  to 
the  correct  names  of  the  trees  or  quality  of  tim- 
ber to  be  obtained  from  them,  was  too  conflict- 
ing to  be  used  in  formulating  any  reliable  state- 
ment of  facts  concerning  them. 

Health  of  the  Pabty. — ^During  the  time  of 
the  survey  the  party  lived  in  camp  in  the  midst 
of  the  swamps,  were  almost  constantly  wet  while 
at  work  from  rain  and  from  wading  through  the 
water  and  mud  of  the  swamps,  and  the  work 
was  fatiguing  in  the  extreme.  Yet  there  was 
no  sickness  except  some  boils  among  the  labor- 
ers, and  in  my  own  case  an  abscess  on  the  hand. 
The  line  was  finished  August  26,  and  as  the  time 
allotted  for  doing  the  work  had  expired,  no  ex- 
tended topography  of  the  hills  was  taken  as  had 
been  intended  originally.  If  this  topography 
were  taken  there  is  little  doubt  that  it  would 
reveal  a  much  more  economical  line  through  the 
hills  than  that  actually  run  over. 

On  September  1,  I  was  placed  in  charge  of 
headquarters  at  Greytown,  and  my  time  till  my 
departure  from  Nicaragua  was  occupied  in  at- 
tending to  all  the  details  of  the  Commission's 
affairs  in  Nicaragua.  Among  other  duties  I 
made  monthly  rounds  of  all  the  camps  occupied 
by  the  hydrographic  parties,  inspected  their  work 


426 


NICARAGUA  CANAL  COMMISSION 


and  forwarded  their  monthly  reports  to  Mr.  A. 
P.  Davis  at  Washington.  Owing  to  the  slow 
means  of  communication  of  the  country,  each  of 
these  rounds  occupied  nearly  half  the  month. 

On  December  4,  when  about  closing  up  the 
affairs  of  the  Commission  in  Greytown,  prepara- 
tory to  leaving  for  Washington  in  company  with 
several  members  of  Mr.  Stuart's  party,  I  re- 
ceived a  telegram  from  the  President  of  the 
Commission  ordering  me  to  hold  all  men  in 
Greytown  until  written  instructions  should  ar- 
rive. These  came  on  December  19,  and  di- 
rected me  to  organize  a  corps  and  proceed  to 
take  the  topography  of  the  country  on  both 
sides  of  the  river  above  the  mouth  of  the  San 
Carlos  river,  and  to  make  borings  to  the  rock,  all 
with  the  view  of  investigating  the  place  as  a  site 
for  a  proposed  dam.  The  topography  was  to  be 
carried  back  on  both  sides  of  the  river  along  the 
ridge  lines  to  verify  the  connection  with  the  in- 
terior hills  of  the  country,  and  also  to  be  carried 
down  along  the  north  side  of  the  San  Juan  river 
to  a  point  one  mile  below  the  mouth  of  the 
Machado  creek.  Accordingly  I  made  up  a  party 
from  the  few  men  left  me.  Two  of  these  were 
sick;  one  with  an  abscess  and  one  with  malainal 
fever.  The  physician  advised  me  that  they  had 
best  go  to  the  States  to  recuperate.  There  were 
left  only  three  men.  But  as  Mr.  A.  P.  Davis 
desired  to  have  two  of  the  gaging  stations  dis- 
continued, two,  more  were  made  available,  in- 
creasing my  party  to  five.  One  of  these,  Moriz 
Bernstein,  was  detailed  to  take  charge  of  the 
borings  and  supplied  himself  with  one  Pierce 
rig  for  driving  pipe  and  one  diamond  drill  out- 
fit. There  happened  to  be  a  large  frame  house 
at  the  junction  of  the  San  Carlos  with  the  San 
Juan  and  in  a  location  verv  convenient  to  the 
work.  This  I  rented  and  in  it  the  party  was 
housed  very  comfortably.     We  left  Greytown 


in  the  river  steamer  on  the  27th  of  December, 
taking  along  20  laborers,  6  for  the  drilling 
party  and  the  remainder  for  the  topographers. 
After  some  searching  we  found  some  of  the  old 
river  survey  stations  to  which  we  tied  the  new 
work.  The  map  furnished  me  with  my  orders 
showed  a  proposed  canal  location  through  the 
hills  in  the  bend  of  the  river  at  Boca  San  Carlos, 
and  I  decided  to  run  a  transit  line  along  this 
location  for  a  basis  on  which  to  tie  the  topog- 
raphy. This  transit  line  was  afterward  con- 
tinued down  the  river  to  the  end  of  the  work. 
Over  this  transit  line  the  level  was  run,  starting 
with  the  elevation  (62.29)  taken  from  station 
Xo.  604  of  the  river  survey,  and  checking  np 
again  within  one-tenth  of  a  foot  on  the  precise 
level  B.  M.  at  Ochoa.  From  the  transit  line 
various  spur  lines  were  run,  some  with  the 
transit  and  less  important  ones  with  a  compass. 
The  ridge  lines  on  both  sides  of  the  river  were 
run  with  the  compass.  The  level  was  run  over 
the  spur  lines  and  over  the  ridge  lines.  Then 
at  every  200  feet,  both  of  the  main  transit  lines 
and  of  the  spur  lines,  a  cross  section  was  taken 
with  compass,  hand  level  and  tape,  locating  each 
10-foot  contour  at  distances  200  feet  apart 
Every  foot  of  all  these  lines  was  cut  through  the 
brush  with  machetes  and  a  great  deal  of  the 
work  was  done  in  heavy  rains,  January  having 
proved  to  be  a  very  rainy  month. 

No  point  of  the  ridge  line  on  either  side  of 
the  river  was  found  to  be  below  110  feet  above 
sea  level,  except  one  small  saddle  on  the  south 
side.  The  length  of  this  opening  at  the  110- 
foot  level  is  500  feet  and  the  lowest  point  in  it 
is  90  feet  above  sea  level.  This  depression 
could  be  utilized  if  thought  advisable,  for  the 
construction  of  a  waste-weir.  The  ridge  seems 
to  be  a  spur  of  the  west  watershed  of  the  Ma- 
chado creek  through  which  the  San  Juan  has 


APPENDIX  VIII.— REPORT   OF   S.   S.   EVANS.   ASSISTANT   ENGINEER 


427 


broken.  Within  one-half  mile  of  the  river  on 
the  Costa  Rican  side  it  expands  into  a  chain  of 
hills  having  peaks  1000  feet  high  and  which 
probably  connects  with  the  interior  mountain 
svstem  of  Costa  Rica. 

On  the  cross  section  of  the  river  five  holes 
were  bored,  the  first  two  of  which  were  separate 
attempts  at  hole  No.  1.  In  neither  of  these 
holes  was  bed  rock  reached,  owing  to  the  great 
number  of  boulders  and  small  stones  encoun- 
tered which  choked  up  the  holes  whenever  the 
drill  was  withdrawn.  We  did  not  have  time 
enough  at  our  disposal  to  persevere  until  this 
difficulty  was  overcome.  These  holes  are  mark- 
ed on  the  accompanying  map  as  hole  No.  1-a 
and  No.  1-b.  They  reached«the  elevations  73 
and  43  above  sea  level  respectively.  In  hole 
No.  2  rock  was  struck  at  2  feet  above,  in  hole 
No.  3  at  15  below,  and  in  No.  4  at  30  feet  above 
sea  level.  On  February  4,  this  work  being 
completed,  the  party  retunjed  to  Greytown. 
Two  of  the  drill  outfits  were  shipped  to  the  De- 
partment of  the  Interior  for  use  in  Arizona,  and 
the  remaining  ones,  together  with  some  boats 
and  other  property  belonging  to  the  Commission, 
were  stored  in  one  of  the  buildings  of  the  Mari- 
time Canal  Company  at  La  Fe.  A  list  of  this 
property  has  been  handed  to  the  Commission  by 
the  store-keeper,  Mr.  Thomas  J.  Boltz.  The 
two  steam  launches  used  on  the  hydrographical 
survey  of  the  lake  and  river,  and  belonging  to 
the  Navy  Department,  were  stored  in  the  care 
of  the  TJ.  S.  Consul  at  Greyto^^^l.  The  care  of 
the  hydrographical  parties  still  in  the  field  was 
turned  over  to  Mr.  H.  C.  Hurd  in  accordance 
with  orders  from  the  President  of  the  Commis- 
sion. It  was  arranged  that  he  should  have  his 
headquarters  at  San  Carlos. 

The  building  used  for  headquarters,  and  also 
that  for  the   storehouse,   were  surrendered  to 


their  owners,  and  on  February  18  the  party  took 
passage  on  the  Atlas  steamer  "Alene,"  arriv- 
ing in  Washington  March  6. 

The  Labor  Question  and  Effects  of  the 
Climate  of  Nicakagua. — ^During  my  fifteen 
months'  residence  in  Nicaragua  I  had  oppor- 
tunity to  observe  the  character  of  the  labor  there 
used,  both  of  the  native  Nicaraguans  and  of 
the  Jamaican  negroes.  Either  the  one  or  the 
other  of  these  two  classes  was  used  in  all  the 
camps  of  the  expedition.  I  noted  the  experi- 
ences of  the  officers  of  the  Caribbean  and  Pa- 
cific Transit  Company  as  well  as  of  many  others 
with  tlie  same  classes  of  men.  I  think  it  is  the 
universal  testimony  of  all  the  assistant  engineers 
to  the  Commission  who  had  to  deal  with  these 
laborers,  that  they  are,  as  a  rule,  very  unsatisfac- 
tory. But  I  do  not  think  that  this  is  due  to  phy- 
sical inability  to  do  a  good  day's  work  or  to  the 
enervating  effect  of  the  climate.  This  latter  I  be- 
lieve is  a  popular  fallacy.  It  is  my  opinion  that 
we  must  look  deeper  than  to  mere  climatic  influ- 
ences to  find  the  true  explanation  of  the  want  of 
efficiency  of  the  labor  here.  It  is  inherent  in 
the  constitution  of  the  races  of  people  who  are 
found  in  these  countries.  They  simply  lack  the 
moral  stamina  to  voluntarily  endure  any  pro- 
longed exertion.  The  American  negroes  are 
generally  credited  with  being  much  better  labor- 
ers than  those  from  Jamaica.  But,  as  negro 
nature  is  about  the  same  the  world  over,  those 
from  the  I 'nited  States  are  probably  better  be- 
cause they  are  held  up  to  a  higher  standard  by 
their  environment.  The  laborers  of  the  coun- 
tries to  the  south  of  us  have  little  training,  are 
entirely  irresponsible,  and  having  no  ambitions 
and  but  few  necessities  they  are  not  incited  to 
better  their  condition  by  incentives  felt  by  peo- 
ple of  better  races.  Consequently  they  are  not 
inclined  to  work  at  all,  except  as  obliged  by  ne- 


428 


NICARAGUA  CANAL  COMMISSION 


cessity,  and  then  only  long  enough  to  supply 
present  needs.  They  seem  to  work  well  enough 
for  a  short  period,  but  are  disinclined  to  any 
continued  effort.     A  foreman  of  one  of  the  rail- 

'm 

way  gangs  who  had  employed  them  on  the  Isth- 
mus of  Panama,  told  me  that  this  fact  was  rec- 
ognized there,  and  that  it  had  been  his  custom  to 
discharge  his  entire  gang  at  the  end  of  each 
month,  hiring  new  ones,  and  taking  on  the  old 
ones  again  at  the  beginning  of  the  following 
month.  Such  a  system  would  no  doubt  require 
an  efficient  police  service  to  keep  in  order  the 
relay  of  idle  men,  but  perhaps  by  following  some 
such  tactics  very  good  results  could  be  obtained. 
Certainly  something  of  a  special  nature  will 
have  to  be  done  in  treating  the  problem  of  labor. 

Aid  to  be  Derived  from  the  Resources  of 
Nicaragua. — Some  assistance  can  be  derived 
from  an  intelligent  utilization  of  the  resources 
of  Nicaragua.  Unfortunately  there  is  probably 
no  coal,  but  there  is  an  abundance  of  timber, 
some  food  supplies  and  some  labor.  The  pro- 
ductiveness of  these  sources  of  aid  could  be  ex- 
pected to  increase  during  the  progress  of  the 
work,  as  the  demand  would  lead  to  development. 

Timber  Supply. — There  are  various  kinds  of 
timber  in  Nicaragua  which,  for  strength  and  du- 
rability, it  is  generally  admitted,  are  far  super- 
ior to  any  that  would  be  imported.  Leaving 
out  of  consideration  mahogany,  cedar,  granadilla, 
rosewood  and  such  other  fine  woods  which  are 
too  valuable  for  extended  use  in  canal  construc- 
tion, some  of  the  most  useful  trees  are  the 
almendro,  cortez,  nispera,  madera  negra,  gavi- 
lan  or  wild  tamarind,  sapodilla,  guanacosto, 
Cottonwood — different  from  that  in  the  United 
States — and  others. 

But,  with  the  exception  of  one  concern  on 
the  Atlantic  coast  which  is  extensively  engaged 
in  exporting  mahogany,  there  are  no  mills  nor 


any  one  engaged  in  the  business  of  taking  the 
timber  from  the  forests  and  preparing  it  for 
commercial  uses.  Such  small  quantities  as  are 
required  to  supply  the  native  demands  are  sawed 
from  the  log  by  hand. 

Owing  to  my  limited  opportunities  for  ob- 
servation I  could  not  say  whether  the  various 
kinds  of  excellent  woods  which  I  saw  in  use 
are  to  be  found  in  sufficient  quantities  to  warrant 
the  establishment  of  saw  mill  plants,  and,  while 
there  is  abundance  of  forest,  it  seems  to  be  a 
fact  that  no  one  variety  of  tree  grows  in  bodies 
or  groves,  but  is  scattered  over  large  areas  and 
is  interspersed  among  worthless  trees.  The 
denseness  of  the  forest  and  difficult  topography 
of  the  hills  united  to  the  expense  of  making 
roads  over  the  ground  usually  softened  by  rains, 
might  make  the  cost  of  assembling  the  logs  at 
mills  so  great  that  competition  in  price  per  foot 
B.  M.  with  imported  timber  would  be  out  of  the 
question. 

But  at  any  rate  where  it  is  necessary  to  lay 
corduroy  for  supporting  railway  tracks  and  other 
roads,  abundance  of  suitable  logs  can  be  had 
close  at  hand,  and  it  is  also  probable  that  suffi- 
cient railwav  cross-ties  of  durable  wood  can  be 
obtained  at  no  greater  cost  than  that  of  im- 
porting inferior  ones. 

In  view  of  the  superior  quality  of  the  Nica- 
raguan  timber,  it  seems  to  me  that  in  case  of 
further  investigation  of  the  canal  question  it 
would  be  profitable  to  make  a  thorough  exami- 
nation of  the  availabilitv  of  the  timber  resources 
of  the  country  and  of  the  probable  cost  of  de- 
livering it  at  the  works  ready  for  use. 

Native  Food  Supply. — There  are  good  pas- 
ture lands  wherever  the  timber  is  cleared  away, 
and  cattle  appear  to  thrive.  There  are  extensive 
grazing  lands  on  the  eastern  side  of  the  lake 
from   which   cattle    are   annually   exported    to 


APPENDIX  VIII.— REPORT   OF   S.   S.   EVANS.   ASSISTANT   ENGINEER 


429 


Costa  Eica.  The  native  market  is  well  supplied 
with  fresh  meat.  The  present  cattle  production 
is  only  limited  by  the  available  market.  It 
easily  could  and  probably  would  develop  to  meet 
the  needs  of  the  canal  laborers  for  fresh  meat. 
Cheese  is  also  produced  in  sufficient  quantity  to 
meet  the  needs  of  the  country,  and  coffee  is  one 
of  the  principal  articles  of  export.  Two  prime 
articles  of  the  diet  of  all  laborers  here  are  plan- 
tains and  beans,  and  these,  with  bananas, 
oranges,  limes,  pineapples  and  yams,  can  be 
produced  in  unlimited  quantities*  and  at  short 
notice. 

Native  Labor  Supply. — This  is  quite  lim- 
ited. The  Nicaraguan  laborer  and  negro  are 
not  easily  trained  to  classes  of  work  with  which 
they  are  not  familiar.  They  can  be  used  as 
woodsmen,  boatmen,  porters  and  for  similar 
work,  but  would  be  nearly  useless  for  heavy  labor 
with  pick  and  shovel  and  the  like.  They  do  well 
enough  for  a  few  weeks,  but  like  all  other  labor- 
ers in  these  countries  cannot  be  depended  upon 
to  remain  steadily  at  work  for  a  prolonged  period. 

I  append  hereto  an  estimate  of  the  probable 
cost  of  a  rock-filled  dam  at  Boca  San  Carlos, 
and  of  a  waste-weir  at  the  same  point. 

The  dam  has  its  crest  at  elevation  115  above 
sea  level.  The  rock-fill  is  20  feet  wide  on  top 
and  has  a  slope  of  2^  horizontal  to  1  vertical  on 
the  down  stream  side  and  on  the  upper  side  a 
slope  of  one  on  one.  The  upper  side  is  covered 
with  an  earth-fill,  sloping  3  horizontal  to  1  verti- 
cal.  The  rock-fill  composing  the  dam  is  de- 
signed to  rest  on  the  hard  rock  bottom  lying 


under  the  river  bed,  the  silt  having  been  re- 
moved by  dredging.  The  waste-weir  is  to  have 
its  crest  at  98  feet  above  sea  level,  be  built  of 
concrete,  be  18  feet  thick  on  top  and  rest  on  the 
rock.  It  is  estimated  on  the  basis  that  it  in- 
creases 0.45  feet  in  thickness  for  each  foot  of 
height.  It  has  a  wing  wall  at  each  end.  It  is 
located  in  the  hill  on  the  south  side,  its  nearest 
end  1800  feet  from  the  end  of  the  dam.  The 
estimate  covers  excavation  of  the  hill  on  the 
down  vStream  side  to  the  level  of  the  crest  of  the 
weir  and  four  feet  below  the  crest  on  the  up- 
stream side.  Between  the  dam  and  the  weir 
there  is  a  small  saddle  or  depression  in  the  hill, 
the  filling  of  which  with  earth  to  the  level,  115, 
is  estimated  for.  The  weir  is  placed  in  the 
higher  ground  because  the  rock  bottom  is  sup- 
posed to  be  higher  there,  thus  lessening  the 
quantity  of  masonry  required. 

The  estimate  is  probably  ample,  as  the  down- 
stream slope  on  the  rock-fill  is  2J  to  1,  whereas 
in  rock-fill  dams  already  constructed,  the  slope 
has  usually  been  1  on  1  on  both  sides.  The 
masonry  in  the  weir  is  also  heavy,  but  this  may 
be  necessary  to  provide  for  the  shock  of  the 
great  volume  of  water  which  will  sometimes 
flow  over  it.  The  weir  provides  for  a  discharge 
of  75,000  cubic  feet  per  second,  with  a  head  of 
8  feet.  If  a  larger  capacity  is  required  the  ex- 
tra cost  would  be  about  in  proportion  to  the  in- 
creased length  of  weir. 

Respectfully  submitted, 

S.  S.  Evans, 
Assistant  Engineer. 


430  NICARAGUA  CANAL  COMMISSION 

Estimate  of  Cost  of  Eock-Fill  Dam  and  Masonry  Waste-Weib  at  Booa  San  Caiujos. 

Crest  of  Dam,  115.     Crest  of  Weir,  98. 

Cu.  yd*.  At 

Earth  excavation  for  weir 851,926             $0.87  $315,212.62 

Soft  rock  excavation  for  weir 108,025                  93  100,468.25 

Masonry  for  weir 46,748                8.80  388,008.40 

Excavation  of  silt  for  dam 1,475,090                  .37  545,783.30 

Eock-fiU  for  dam 1,358,125                1.50  2,027,187.50 

Earth  for  dam 475,541                  .37  175,950.17 

Earth-fill  for  small  dam,  across  saddle 23,885                 .37  8,837.45 

Kegulating  works,  1200  feet $266.67  320,004.00 

Total $3,881,446.6» 


APPENDIX   IX 


REPORT 


ON  THE 


PRECISE  LEVEL  LINE 


FROM  THE 


CARIBBEAN  SEA  TO  THE  PACIFIC  OCEAN 


BY 

STEPHEN   HARRIS 

Assistant  Engineer 


CONTENTS 

PAGE 

Nature  of  Work 435 

Instrumental  Equipment 435 

Kate  of  Progress 430 

Long  Sights ' 437 

Organization  of  Party 437 

Method  of  Work 438 

Atmospheric  Conditions 430 

Limit  of  Error 430 

Personnel  . 440 

Field  Records 440 

Final  Keductions 440 

Greytown  Tide  Gages 441 

Benches  Xos.  1  to  21 443 

Crossing  Lake  Nicaragua 460 

Benches  Xos.  22  to  24 467 

Brito  Tide  Gages 470 

Checks  with  other  Lines 471 

The  Third  Line 473 

Probable  Error -, 474 


28 


APPENDIX  IX 


W.VSHINOTON,  D.  C,  April  15,  1899. 

!Mr.  E.  S.  Wjieeler,  Chief  Engineer,  Nicaragua 
Canal  Commission. 

Sir: — The  following  report  of  the  work  done 
and  results  obtained  by  the  Precise  Ix^vel  Party 
under  my  charge  i.^  herewith  n^spectfnlly  sub- 
mitted. 

The  work  assigned  us  was  to  carry  two  precise 
level  lines  ahmg  the  route  of  the  canal  from 
(Jreytown,  the  Atlantic  terminius,  to  Brit4),  the 
Pacific  terminus,  except  that  connection  was  to 
be  made  across  Lake  Nicaragua  by  gages  estab- 
lished at  San  Carlos  and  at  Las  Lajas. 

Along  the  route  of  the  canal  at  suitable  places, 
about  five  miles  apart,  benches  were  to  be  es- 
tablished with  which  the  ordinary  level  work 
could  be  connected. 

The  levels  and  rods  used  in  this  work  were 
borrowed  from  the  Engineer  Corps,  U.  S.  A. 
The  levels  were  marked  Xo.  1  and  No.  3,  and 
were  made  bv  J.  Kern  of  Aarau,  Switzerland. 
The  rods  were  marked  X,  XIII,  XV  and  XVI. 
In  these  levels  the  bubble  rests  on  top  of  the 
rings  when  in  use,  and  is  carried  in  the  hand 
when  the  instrument  is  being  moved.  A  mir- 
ror is  provided  by  wdiich  the  bubble  can  be  read 
without  moving  the  eye  from  the  eye-piece. 
There  is  a  screw  with  a  very  fine  thread  under 
one  wye  which  is  used  for  the  final  leveling  of 
the  telescope  when  j>ointed  on  the  rod.  There 
are  three  leveling  screws  and  a  circular  or  box 
level   for   convenience   in   setting.     There   are 


three  horizontal  wires,  and  the  mean  of  the  three 
readings  is  taken. 

The  leveling  rod  is  made  in  one  piece,  three 
meters  long,  four  inches  wide  on  the  face,  and 
strengthened  by  a  piece  at  the  back,  making  a 
T-shaped  cross  section.  It  is  self-reading,  grad- 
uated to  centimeters,  and  is  read  bv  estimation 
to  millimeters.  The  decimeters  are  figured  on 
one  side  of  the  graduation,  and  the  centimeters 
on  the  other.  A  box  level  is  attached  to  the 
rod  to  enable  the  rodman  to  hold  it  vertical,  and 
this  in  turn  is  tested  by  means  of  a  plumb  line. 

]iefore  determining  any  elevations  on  the 
(*aual  line,  both  instniments  were  carefully  ex- 
amined and  their  constants  determined  as  accu- 
rately as  was  possible  under  the  existing  circum- 
stances. For  instrument  Xo.  1  the  value  of  one 
division  <;n  the  bubble  was  found  bv  trial  to  be 
2.91  sec.  The  bubble  was  marked  2.85  sec. 
I'he  value  of  a  division  appeared  constant  for 
diflFerent  parts  of  the  bubble-tube. 

The  telescope  rings  were  found  to  be  as  nearly 
equal  as  could  be  determined  in  the  field,  the 
level  bubble  not  showing  a  variation  of  more 
than  one  division  when  the  telescope  was  re- 
versed in  the  wyes. 

The  object  glass  did  not  seem  to  be  perfectly 
centered,  but  was  not  enough  out  to  interfere 
with  the  work. 

A  stadia  table  was  calculated,  giving  the  num- 
ber of  feet  equivalent  to  the  space  on  the  rod 
intercepted  between  the  extreme  wires.     This 


436 


NICARAGUA   CANAL  COMMISSION 


space  being  151  mm.  at  100  feet  The  rests 
for  the  striding  level  were  somewhat  worn,  so 
that  it  was  necessary  to  see  that  it  was  always 
placed  in  the  same  position  on  the  telescope. 

For  instrument  Xo.  ?5,  tlie  value  of  one  divi- 
sion on  the  level  was  2  J  sec.  The  telescope 
rings  were  found  to  be  j)ractically  equal,  and  the 
object  glass  well  centered.  A  stadia  table  was 
calculated  giving  the  number  of  feet  equivalent 
to  the  number  of  millimeters  on  the  rod  inter- 
cepted between  the  extreme  wires,  this  being 
140  millimeters  at  100  feet.  *  The  rods  were  ex- 
amined and  found  to  agree  with  each  other  in 
length,  and  the  attached  levels  were  adjusted  so 
that  when  the  bubble  was  in  the  center,  the  rods 
were  vertical.  The  rods  were  provided  with 
foot  plates.  These  could  not  be  used,  as  much 
of  the  country  passed  over  was  swamp,  and  all  of 
it  covered  bv  a  mass  of  roots  wliich  would  have 
been  very  hard  to  remove  when  placing  the 
plates. 

We  at  first  used  hard  wood  tuniing  points  3^" 
s<iuare  and  10"  long,  strengthened  with  an  iron 
band  on  top,  and  having  an  inch  pin  sunk  in  the 
middle  of  a  two-inch  hole  in  the  center  of  the 
head.  The  points  were  driven  with  a  heavy 
iron  mall,  and  carried  fonvard  with  the  rods. 
In  the  swampy  ground  we  were  obliged  to  drive 
piles  for  turning  points,  and  in  places  for  the 
instrument,  using  on  several  occasions,  piles  10' 
long.  The  first  turning  i)oints  lasted  to  Ochoa, 
and  then  we  used  in  their  place,  3"  stakes  w^ith 
ten-penny  nails,  driven  for  turning  points,  not 
removing  the  stakes  as  we  went  forward.  Each 
morning  before  commencing  work  the  coUima- 
tion  adjustment,  the  bubble  adjustment,  and  the 
rods  were  examined,  and,  if  necessary,  were  cor- 
rected. The  record  of  these  adjustments  was 
written  before  the  record  of  the  dav's  work. 

At  Grevtown  a  trial  mile  was  laid  off,  and 


both  instruments  tried  twice  over  the  course. 
Instrument  Xo.  1  closed  on  the  initial  point  by 
3.7  mm.  and  bv  2.3  mm.  Instrument  Xo.  3 
(»losed  on  the  initial  point  by  0.3  nun.  and  by 
4.2  mm. 

The  organization  of  the  party  varied  as  the 
work  progressed.  At  first  the  chief  of  party 
was  free  to  watch  the  work  of  both  instruments, 
to  look  over  the  line  ahead,  and  to  attend  to  mov- 
ing camp  and  securing  supplies.  There  was  an 
instrument  man  and  a  recorder  for  each  instru- 
ment, and  a  man  in  camp  to  copy  notes;  and  it 
was  expected  that  another  American  would  be 
assigned  to  the  party  to  cut  line  ahead.  The 
rodmen  were  at  first  Jamaica  negroc»s  who  were 
replaced  by  Spaniards  as  soon  as  we  could  get 
them.  It  was  originally  intended  that  there 
should  be  seven  Americans  in  the  party.  This 
number  decreased  as  we  moved  toward  the  Pa- 
cific and  at  Brito  there  were  but  four. 

The  rate  of  speed  of  the  party  varied  consid- 
erablv.  The  heavv  and  incessant  rain  on  the 
east  side  was  a  great  hindrance,  and  the  hard 
dashes  came  right  through  the  carriage  imibrel- 
las  w^e  used,  and  soon  fogged  the  glasses.  The 
countrv  up  the  vallev  of  the  Deseado  was  verv 
much  broken  and  continued  bad  till  we  reached 
the  San  Juan  river  at  Ochoa.  On  the  Deseado 
when  the  rain  was  moderate  and  the  other  con- 
ditions favorable,  we  made  half  a  mile  a  day. 
Another  source  of  delay  for  this  part  of  the  line 
was  the  time  lost  in  moving  camp.  Travel  was 
so  hard  that  it  was  found  necessary  to  keep  the 
camps  about  five  miles  apart;  and  the  moving 
from  camp  to  camp,  sometimes  by  rivers  blocked 
by  logs,  sometimes  packing  on  men's  backs,  used 
up  a  great  deal  of  time.  The  labor  when  the 
party  w^as  not  near  a  source  of  supply  was  a 
serious  question.  As  the  wants  of  the  men 
are  few,  thev  need  verv  little  monev,  and  thev 


APPENDIX  IX.— REPORT  ON  PRECISE  LEVELS 


437 


do  not  care  to  work  steadily,  the  average  time  ' 
for  a  man  being  about  a  month.  Then  the 
Spaniards,  who  are  very  much  better  and  more 
reliable  than  the  negroes,  do  not  speak  English. 
From  dreytown  to  Oohoa  the  average  rate  of 
speed  was  10  miles  a  month.  As  we  traveled 
west  the  speed  of  the  party  increased;  we  found 
level  ground  by  holding  the  river  bank;  we 
lost  less  time  moving  camp  and  could  keep  the 
camps  further  apart,  and  the  rainfall  decreased. 
While  on  the  river  banks,  we  in  places  had 
to  work  our  way  round  steep  bluffs,  and  in 
places  were  for  miles  in  water  up  to  our  waists, 
sometimes  being  obliged  to  drive  a  short  pile 
under  each  tripod-leg  to  keep  the  top  of  the 
tripod  above  water.  Five  or  six  miles  below  San 
Carlos,  the  water  at  the  edge  of  the  river — 
that  is  where  the  grass  and  trees  begin — was 
from  six  to  twenty  feet  deep  for  a  mile,  and 
here  we  were  obliged  to  take  longer  sights  than 
usual,  and  zigzag  across  the  river,  placing  the  top 
of  the  instriiment  on  cut-off  trees,  and  driving 
piles  for  turning  points,  making  the  foresights 
and  l)acksights  ecjual.  The  longest  of  these 
sights  was  1112  feet,  and  the  rods  could  just  be 
read  in  a  favorable  light  at  that  distance.  The 
readings  were  checked  by  putting  rubber  bands 
on  the  rods,  and  any  large  error  guarded  against 
by  measuring  from  the  turning  points  to  the 
water  at  practically  one  time,  and  seeing  that  the 
water  elevations  increased  regularly  for  the  three 
long  sights.  The  distance  from  the  first  to  the 
second  turning  point  was  2215  feet,  and  the  in- 
crease in  elevation  of  the  surface  of  the  river 
was  .042  feet.  From  the  second  to  the  third 
turning  point  was  173G  feet  and  the  increase  in 
elevation  of  the  river  was  .036  feet.  From  the 
third  to  the  fourth  was  1704  feet,  and  the  in- 
crea:=e  in  elevation  was  .037  feet.  The  trees  did 
not  form  a  very  steady  support,  as  any  slight 


motion  of  the  wind  or  water  was  communicated 
to  the  instrument,  and  it  was  necessary  to  select 
a  time  when  the  water  was  calm  and  the  wind 
had  died  down.  The  readings  were  taken  by 
two  observers  in  a  boat  which  was  wedged  into 
the  vegetation  near  the  instrument,  one  observer 
reading  when  the  other  noticed  that  the  bubble 
had  come  to  a  rest.  To  have  gone  round  this 
mile  of  water  would  have  added  to  our  line 
seven  or  eight  miles  of  badly  broken  country 
and  swamp.  On  the  upper  river  when  every- 
thing was  favorable,  we  made  about  a  mile  a 
day,  and  west  of  the  lake,  from  two  to  three 
miles.  Our  running  west  of  Ochoa  varied  from 
ten  to  twenty-five  miles  a  month. 

When  we  could  get  plenty  of  native  help,  and 
our  party  was  organized  to  do  its  best  work,  the 
method  of  procedure  and  arrangement  of  the 
men  was  as  follows: 

The  line  was  first  cut  out  ahead,  holding  the 
river  bottom  wherever  practicable,  even  to  the 
extent  of  doubling  the  length  of  the  line.  The 
line  was  kept  as  nearly  in  one  direction  as  pos- 
fiible,  but  all  trees  that  could  not  be  cut  in  a 
few  minutes  were  left  standing.  This  w^as  done 
by  a  party  consisting  of  an  American  and  five 
natives  working  in  the  shape  of  a  V.  One  na- 
tive going  ahead,  and  two  following  on  each  side 
to  widen  and  clear.  In  this  way  about  a  mile 
of  line  could  be  cut  in  a  dav.  Sometimes  the 
underbrush  was  found  so  heavy  and  the  swamp 
so  hard  to  force  through,  that  it  was  necessary  to 
have  two  ])arties  cutting  in  order  to  keep  ahead 
of  the  instruments. 

With  the  first  instruni(»nt  there  were  two 
Americans  and  seven  natives.  One  American 
for  instninient  man  and  one  for  recorder,  two 
natives  as  rodnien,  one  to  furnish  and  drive  turn- 
ing points,  one  to  carry  the  instrument,  one  to 
carrv  the  umbrella  and  lunch,  and  two  others 


438 


NICARAGUA  CANAL  COMMISSION 


to  cut  line.  A  great  deal  of  clearing  had  to  be 
done  hy  this  party,  and  all  the  natives  were  used 
for  that  purpose. 

The  second  level  party  consisted  of  one 
American  and  five  natives.  The  American  as 
instrument  man  and  recorder,  two  natives  as 
rodmen,  one  native  to  carry  the  instrument,  one 
to  carry  the  umbrella  and  lunch,  and  one  to  cut 
line  and  follow  with  the  boat.  This  party  fol- 
lowed the  first  party  using  turning  points  in  the 
same  places,  as  any  change  would  mean  clearing 
a  new  line. 

Resides  the  three  parties  mentioned,  there 
was  an  American  in  camp  copying  notes  and 
making  arr.angements  for  moving  ahead,  and  a 
cook  and  a  helper.  The  entire  party  then  con- 
sisted of  five  Americans  and  ninetcnm  natives. 

As  the  conditions  were  such  that  it  was  not 
to  be  expected  that  the  instrument  would  hold 
its  adjustment  as  well  as  in  onlinary  work  in 
the  United  States,  great  care  w^as  exercised  to 
make  the  foresights  and  backsights  equal,  and 
every  j)recaution  taken  that  the  instrument  be 
not  disturbed  between  the  reading  of  the  back- 
sight and  foresight,  so  that  the  slight  v(»rtical 
angle  always  present  might  remain  constant  for 
that  time.  We  made  the  sights,  wIhmi  possible, 
about  200  feet.  This  is  shorter  than  the  usual 
length  of  sight,  and  we  at  first  tried  to  get  300' 
sights.  We  found  this  too  long  for  the  j)oor 
light  in  the  dense  forests,  and  also  to  require 
very  much  more  cutting,  so  that  the  fastest  time 
w^as  made  with  200'  as  the  maximum  length  of 
sight.  As  part  of  the  country  was  very  badly 
broken  and  very  steep  hillside,  our  minimum 
sight  was  determined  by  the  focusing  power  of 
the  telescoiKJ,  and  was  15  feet.  We  averaged 
in  the  country  near  the  divide,  50  set-ups  to  the 
mile,  and  along  the  upper  part  of  the  San  Juan 
river,  25  set-ups  to  the  mile.     At  first  we  made 


the  sights  wpial  by  steel  tajx?   measurements, 
which  gave  us  an  additional  check  on  the  interval 
between  the  wires,  but  finally  w^e  were  obliged 
to  rely  entirely  upon  stadia  measurements,  as 
the  work  with  the  tape  took  up  too  much  time. 
Our  method  of  work  was  as  follows: 
AitvT   taking    a    sight   the    instrument    man 
walked  past  the  foresight,  selcH^ting  a  point  for 
the  instrument.     The  rodman  who  had  been  at 
the    backsight    advanced    counting    his    steps 
from  the  new  backsight  point  to  the  instrument, 
and  going  an  equal  number  beyond.     The  in- 
strument man  read  the  distance  to  the  new  back- 
sight rod,   and   then   set   the   foresight   rod   to 
within  a  foot  of  the  same  distance.     The  back- 
sight rod  was  then  read  and  recorded,  and  then 
the  foresight;  and  then  the  backsight  again,  and 
the  foresight,  to  check  the  first  readings  and  see 
if  there  had  been  any  marked  change  in  the  in- 
strument   height.     If   the    readings    showed    a 
change,  they  wen*  discarded,  the  instrument  was 
made  more  solid,  and  an  effort  made  to  allow  less 
time  to  elapse  between  the  readings.     At  the 
end  of  fiv(»  miles  when  the  party  reached  a  num- 
bered bench,  a  change  in  the  order  of  reading 
would  be  made;  the  foresights  being  read  first, 
so    preventing    a    cumulative    error    from    the 
changed    height    of    instrument.      By    reading 
backsights  first  wuth  one  instrument  and  foi*e- 
sights  first  with  the  other,  these  small  changes 
could  b(»  watched,  and  we  found  that  on  sand  or 
clay,   with  very   little  vegetal)le  matter,   there 
was  a  slight  settlement  of  the  instrument — while 
on  the  swamps  where  the  ground  was  just  above 
water  level,  and  wherever  there  was  a  mass  of 
roots  and  vegetable  matter  reaching  below  the 
points  of  the  tripod,  the  instrument  showed  a 
tendency  to  rise.     In  the  countiy  through  which 
we  passed,  these  two  were  very  nearly  equal. 
When  the  readings  of  the  three  wires  w^re 


APPENDIX  IX.— REPORT  ON  PRECISE  LEVELS 


439 


recorded,  the  spaces  intercepted  on  the  rod  be- 
tween the  center  and  the  outside  wires  were 
written  down.  These  interv^als  shonhl  be  equal 
if  the  ^vires  were  evenly  spaced.  In  onr  instru- 
ments they  were  not  evenly  spaced  and  the  in- 
tervals were  not  quite  equal.  If  the  readings 
did  not  show  the  intervals  nearly  equal,  and  one 
of  them  a  certain  fixed  percentage  of  the  other, 
there  was  an  error  in  the  reading,  and  the  rods 
were  re-read.  For  the  calculation  of  the  next 
elevation,  and  for  a  check  on  the  previous  work, 
a  third  of  the  sum  of  the  three  readings  was 
recorded,  and  if  tlie  work  wa!^  correct,  this  would 
differ  from  the  middle  reading  by  one-third  the 
difference  of  the  intercepted  inten-als.  From 
the  mean  backsight  and  foresight  readings,  the 
elevation  of  the  new  backsight  was  figured.  The 
distances  and  rod  numbers  for  ofliice  reduction 
were  recorded,  and  the  party  was  ready  to  again 
advance.     It  was  at  first  intended  to  note  the 

ft 

distance  the  bubble  was  from  the  center  at  the 
time  of  reading  anil  to  make  a  coiresponding 
reduction.  It  was  found  that  in  the  swampy 
ground  and  tangle  of  vines  everv'where  present 
on  the  line,  the  recorder  could  not  do  this  work 
without  di^turbing  the  instrument,  and  tliat  if 
it  were  atte»mpted  by  the  instrument  man,  the 
increased  length  of  time  between  the  back-  and 
foresights  would  introduce  a  greater  error  than 
that  eliminated  by  noting  the  exact  position  of 
the  bu])ble;  as  it  could  generally  be  ke])t  within 
at  least  a  quarter  of  a  division  of  center  while 
reading. 

While  there  were  manv  ])ettv  annovances 
from  insects,  rain  and  mud,  the  conditions  were 
almost  ideal  for  good  levels.  In  the  dense  tropi- 
cal forest  in  which  we  worked  there  was  absolute 
stillness  and  the  bubble  w^as  unusuallv  stable. 
The  whole  length  of  sight  was  generally  shielded 
from  the  direct  rays  of  the  sun,  so  that  the  rods 


appeared  steady  and  clear,  and  when  sighting 
across  the  river  it  was  possible  to  keep  the  in- 
strument in  the  shade,  and  the  even  temperature 
near  the  water  prevented,  on  these  long  sights, 
anv  movement  of  the  rod  from  refraction.  The 
worst  country  we  passed  over  was  the  stretch 
from  the  seashore  to  the  railroad  bridge  over  the 
Deseado,  near  our  bench  Xo.  3.  There  was  a 
stiff  breeze  blowing  all  the  time,  there  were  no 
trees  in  the  swamp,  and  when  it  was  not  raining, 
the  sun  beat  directlv  down  on  the  line  makins: 
the  refraction  verv  bad. 

The  work  of  the  first  or  leading  party  w^as 
much  more  difficult,  and  as  the  organization  and 
duties  of  the  laborers  differed  in  the  two  parties, 
their  position  could  not  be  changed  to  advan- 
tage. The  greater  part  of  the  way  from  Grey- 
town  to  the  Boca  San  Carlos,  I  kept  instrument 
Xo.  1  ahead  with  my  two  most  experienced  men 
as  instrument  man  and  recorder.  The  second 
party  followed  closely,  setting  their  turning 
l)oints  in  the  same  places  as  the  first  party,  as 
any  change  would  mean  clearing  a  new  line, 
ify  instrument  men  were  changed  at  the  Boca 
San  Carlos,  and  before  we  reached  Bench  Xo. 
13,  one  of  the  new  men  received  an  appointment 
in  the  armv. 

At  bench  Xo.  13,  I  took  instrument  Xo.  1 
and  did  my  ow^n  recording,  part  of  the  time 
running  ahead,  but  most  of  the  time  keeping 
behind  instrument  Xo.  3.  •  I  could  start  in  a 
day's  run  behind  the  first  party,  and  catch  up 
with  them  bv  the  end  of  the  third  dav,  and  this 
gave  me  one  day  in  four  to  go  ahead  on  line  and 
for  other  work.  In  very  difficult  places,  such 
as  the  long  sites  on  the  river  below  San  Carlos, 
both  i)arties  worked  together  first  using  one  in- 
strument and  then  the  other. 

If  the  levels  at  anv  time  showed  a  difference 
greater  than  .03  feet  into  the  square  root  of  the 


440 


NICARAGUA  CANAL  COMMISSION 


number  of  miles  run  by  one  level,  the  lines 
were  re-nin.  The  re-runnings  were  nearly  all  in 
the  broken  hilly  country.  In  the  river  bottoms 
where  the  lines  were  practically  level,  the  ele- 
vations given  by  the  instruments,  kept  more 
nearly  the  same  distance  apart. 

Instrument  Xo.  1  was  kept  ahead  from  Grey- 
town  to  the  Boca  San  Carlos,  and  instrument 
No.  3,  from  the  Boca  San  Carlos  to  Brito. 
With  instrument  No.  1  from  ]iench  Xo.  1  to 
Bench  No.  8  at  the  Chanchos  river,  G.  F.  Scv- 
mour  was  observer  and  J.  A.  ^litchcll  recorder. 
From  Bench  No.  8  to  Bench  Xo.  11  at  the 
Boca  San  Carlos,  (t.  F.  Sevmour  was  obsen^er 
and  A.  E.  L.  Pain  recorder.  From  Bench  Xo. 
11  to  Bench  Xo.  13  at  La  Cruz,  John  Car- 
michael  was  observer  and  A.  E.  L.  Pain  recorder. 
From  Bench  Xo.  13  to  Bench  Xo.  2-1  at  Brito, 
Stephen  Harris  was  obsen^er  and  recorder. 

With  instrument  Xo.  3,  R.  B.  Post  was  ob- 
server, and  E.  S.  Wilson  recorder  from  Bench 
Xo.  1  to  Bench  Xo.  11,  at  the  Boca  San  Carlos. 
From  Bench  Xo.  11  to  Bench  Xo.  1-1  at  Ma- 
chuca,  L.  E.  Lannan  was  observer  and  E.  S. 
Wilson  recorder.  From  Bench  Xo.  14  to  Bench 
No.  24  at  Brito,  L.  E.  Lannan  was  observer  and 
J.  O.  Jones  recorder.  J.  O.  Jones  kept  the 
office  copy  of  the  notes  and  had  charge  ot  tlie 
camp  outfit  from  Grey  town  to  ilachuca. 

1  had  A.  E.  L.  Pain  moving  camp  and  cut- 
ting line  from  BeJich  Xo.  13  at  La  Cruz  to 
Bench  Xo.  20  at  San  Carlos,  and  F.  K.  Torring- 
ton  cutting  line  and  moving  cam})  from  Castillo 
to  Brito.  I  kept  with  me  two  Spaniards  as  rod- 
men  from  Greytown  to  Brito,  Leonidas  Ochoa, 
a  Colombian,  and  Kamon  Hurtado  of  Kivas. 

The  })arty  landed  in  Greytown,  Saturday,  De- 
cember 18  and  spent  from  that  time  till  January 
5  in  testing  instruments,  collecting  the  camp 
outfit,  and  working  on  the  Greytown  tide  gages. 


Work  on  the  level  line  was  commenced  January 
G,  and  was  finished  Xovember  2,  18DS. 

The  field  records  were  in  27  ordinary  level 
books,  13  for  instrument  Xo.  1,  and  14  for  in- 
strument Xo.  3.  These  books  gave  the  readings 
as  r(»corded  each  day  with  the  elevations;  those 
east  of  the  lake  being  derived  from  the  Canal 
Comj)any's  bench  at  the  machine  shop  at  Grey- 
town; those  west  of  the  lake  being  derived  from 
the  Canal  Company's  Pacific  levels  by  using  a 
bench  near  Las  Lajas  on  the  west  shore  of  Lake 
Nicaragua  made  by  J.  W.  G.  Walker,  assistant 
engineer. 

Xo  corrections  to  the  elevations  for  lack  of 
adjustment  in  the  level,  or  for  variations  from 
the  standard  in  the  graduation  of  the  rods,  were 
made  in  the  field. 

There  was  also  a  cross  section  book  used  as  a 
bench  book  giving  a  sketch  showing  the  location 
of  each  bench,  the  elevations  at  each  bench,  and 
of  i)roniinent  marks  between  it  and  the  next 
bench,  and  the  checks  with  other  lines,  and  there 
were  copied  records  of  the  field  notes  for  both 
instruments  as  far  as  Bench  Xo.  14  at  Machuca. 
In  addition  to  these  records,  there  was  given  to 
us  at  Washington,  the  records  of  the  tide-gage 
readings  at  Greytown,  and  at  Brito,  the  Atlantic 
and  Pacific  terminals  of  the  canal,  and  the  gage 
readings  at  San  Carlos  and  Lajas  by  which  the 
levels  on  the  two  sides  of  the  lake  were  to  be 
connected. 

The  work  then  still  to  be  done  was  to  have  the 
rods  compared  with  the  International  Standard 
dieter,  and  correct  the  original  readings  accord- 
ingly, to  apply  a  correction  to  the  work  corre- 
sponding to  the  observed  want  of  adjustment 
and  the  difference  between  the  backsights  and 
foresights,  and  to  refer  all  elevations  to  mean 
Atlantic  sea  level,  and  to  see  how  much  the 
Pacific  mean  sea  level  differed  from  the  Atlantic. 


APPENDIX  IX.— REPORT  ON  PRECISE  LEVELS 


441 


The  new  elevations  obtained  in  this  way  mnst 
then  be  recorded  in  snch  form  as  to  be  easily 
accessible  and  the  bench  marks  so  described  as 
to  be  easily  found.  In  this  work,  which  was 
done  in  Washington,  I  was  asais?ted  by  Louis  E. 
Lannan  and  James  O.  Jones. 

The  rods  were  compared  with  the  Interna- 
tional Standard  Meter  bv  the  C^oast  Sni*vev 
Office  of  Standard  Weights  and  Measures,  and 
a  table  was  sent  us  giving  the  correction  for  each 
decimeter  of  each  of  the  four  rods.  The  cor- 
rections were  very  slight,  the  maximum  being 
seven-tenths  of  a  millimeter  for  the  eleventh 
decimeter  of  rod  XVI.  These  corrections  did 
not  vary  regularly  from  top  to  bottom  of  the 
rod,  and  to  use  them  at  all  it  was  necessarv  to 
correct  each  reading.  To  do  this,  the  original 
readings  were  copied  on  printed  sheets  made  for 
this  purpose,  and  then  the  corrected  readings 
inserted  and  the  elevations  worked  out  over 
again.  As  the  calculations  in  the  field  were 
made  under  verv  unfavorable  circumstances, 
many  of  them  at  night  under  a  wet  mosquito 
bar,  this  recalculation  gave  the  necessary  check 
on  the  accuracy  of  the  field  computation. 

The  corrections  for  lack  of  adjustment  were 
made  as  the  elevations  were  recalculatcnl,  taking 
the  lengths  of  the  sights  from  the  millimeti^rs 
intercepted  on  the  rods  by  the  out:»ide  wires.  As 
the  sights  were  kept  nearly  equal,  these  correc- 
tions amounted  to  practically  nothing.  For  in- 
strument Xo.  il  the  total  accMiniulated  correction 
at  the  end  of  the  line  was  one  millimeter,  and 
for  instrument  No.  1,  the  corrections  balanced 
out  at  bench  Xo.  1»{,  and  we^st  c»f  tliat  bench, 
while  the  adjustments  were  examined  each 
morning,  no  corrections  were  noted  for  tlie  in- 
strument, as  the  adjustment  varied  sliglitly,  with 
the  focusing,  due  to  a  fall  the  instrument  had 
at  that  place. 


The  elevations  of  all  points  likely  to  be 
wanted  for  future  use  were  then  converted  from 
meters  to  United  States  feet  by  using  the  ratio 
one  meter  equals  39.37  inches. 

These  elevations  with  a  description  of  the 
points  where  they  were  taken,  will  be  given  in 
the  following  pages.  A  sketch  of  a  numbered 
bench  will  be  given  first  and  will  be  followed  by 
the  elevations* and  description  of  the  points  read 
near  this  bench,  and  between  it  and  the  succeed- 
ing numbered  bench.  For  the  purpose  of  show- 
ing there  can  be  no  large  error  in  our  work,  there 
is  afterward  given  a  comparison  of  our  levels 
with  those  of  a  third  line  fonned  bv  lines  run 
by  H.  H.  Trundle,  assistant  engineer,  from  Grey- 
town  to  Ochoa ;  F.  L.  Stuart,  assistant  engineer, 
from  Ochoa  to  San  Carlos;  the  Canal  Co.  and 
J.  W.  G.  Walker,  assistant  engineer,  from  San 
Carlos  to  Brito. 

The  Greytown  tide-gage  readings  from  which 
mean  sea  level  is  deduced,  were  taken  between 
Januarv^  14,  1808  and  September  14,  1898. 
The  first  gages  were  placed  opposite  the  Canal 
Company's  building  at  La  Fe  and  about  half  a 
mile  west  of  the  Greytown  light-house,  and  150 
feet  noi-theast  of  our  Xo.  1  bench. 

They  were  protected  from  the  waves  by  a  sand- 
bar which  was  forming  some  500  feet  out  to  sea. 
An  effort  was  made  in  jdacing  gages  at  this 
point  to  get  them  as  near  as  possible  to  the  open 
sea,  and  so  make  sure  they  would  not  be  affected 
by  the  discharge  from  the  river.  As  the  coast 
line  is  changing  ra})idly  at  this  point,  there  are 
several  breaks  in  tin*  recc^rd,  causcnl  bv  storms 
cariying  away  the  gages.  The  first  gages  were 
staff  gages,  and  then  a  box  gage  was  added. 
The  readings  were  taken  at  this  place  till  April 
3,  when  the  bar  closed  in  front  of  the  gage  and 
cut  it  off  from  the  sea.  The  gage  was  then 
moved  to  the  mouth  of  the  Itio  Indio,  3^  miles 


442 


NICARAGUA  CANAL  COMMISSION 


northwest  of  La  Fe  and  readings  were  taken 
there  from  April  7,  1898,  to  June  30,  1898. 
At  that  time  a  new  passage  had  formed  from 
the  Grey  town  lagoon  to  the  sea  past  the  Grey- 
towm  light-house.  The  gage  was  changed  to 
this  place  and  readings  taken  from  July  8  to 
September  14. 

The  gages  at  these  three  places  were  referred 
to  the  Canal  Company's  zero,  by  connecting 
them  with  our  permanent  bench  Xo.  1  and  us- 
ing 2.520  ft.  as  the  elevation  of  that  bench. 
The  gage  was  read  everv'  half  hour.  The  half- 
hourly  readings  have  been  plotted  as  ordinates, 
and  a  curve  drawn  showing  the  rise  and  fall  of 
tlie  sea  during  the  twenty-four  hours.     From 

this  curve,  mean  sea  level  for  the  dav  was  ob- 

'  «.■ 

tained  by  finding  a  horizontal  line  having  equal 
areas  above  and  below%  betw^een  it  and  the  curve, 
the  difference  between  this  lino  and  the  Canal 
Company's  zero  giving  the  mean  height  of  the 
sea  for  that  dav.  These  dailv  mean  sea  level 
values  were  then  plotted  as  ordinates,  the  line 
joining  their  extremities  showing  the  variation 
of  mean  dailv  sea  level.  There  are  several 
marked  changes  in  the  height  of  this  line,  the 

most  noticeable  of  which  is  that  between  Julv 

»■ 

17  and  21,  during  which  time  there  was  a 
change  in  mean  sea  level  of  nearly  a  foot.  This 
change  coincides  with  the  heaviest  rainfall  dur- 
ing the  period  the  readings  were  taken. 

On  July  19,  2.42  inches  of  rain  fell,  and  on 
Julv  20,  5.18  inches.  In  order  to  see  if  there 
was  any  connection  between  the  rainfall  and 
the  record  of  the  gage,  a  curve  was  plotted  show- 
ing the  accumulated  excess  or  deficiency  of  the 
rainfall  as  compared  with  the  average  from  Jan- 
uary 1  to  October  31.     The  comparison  of  these 


curves  shows  either  that  the  height  of  the  sea 
near  the  gage  was  affected  by  the  rain,  or  that 
both  were  due  to  the  same  cause,  the  northeast 
wind  which  brought  the  rain. 

The  mean  of  all  the  daily  mean  sea  levels  giv- 
ing each  day  an  equal  value,  showed  mean  sea 
level  to  be  .524  ft.  below  the  Canal  Company's 
zero.  Quite  a  number  of  days  are  missing  in 
the  record,  as  the  gages  were  often  disturbed  by 
storms,  and  giving  each  month  an  ec^ual  value, 
changes  this  figure  to  .527  ft,  below  the  Canal 
Company's  zero.  Again  if  29-day  periods  are 
selected  as  is  usual  in  this  work,  the  figure  is 
changed  to  .4G4  ft.  below  the  Canal  Company's 
zero,  but  by  this  method  it  is  only  possible  to 
include  145  out  of  212  readings  taken,  or  G8 
per  cent,  of  the  readings.  Taking  the  different 
places,  the  readings  at  La  Fe  showed  mean  sea 
level  to  be  .555  ft.  below  the  Canal  Company's 
zero;  those  at  Rio  Indio  .668  ft.  below;  and 
those  at  Greytown  light-house  .337  ft.  below. 
The  value  .524  ft.,  equivalent  to  .1597  meter, 
has  been  taken  as  probably  nearest  the  true 
value,  and  none  of  the  other  values  differs  from 
this  by  as  much  as  two-tenths  of  a  foot.  This 
makes  the  height  of  our  permanent  bench  No. 
1,  3.044  ft.  above  mean  sea  level,  which  is  equiv- 
alent to  .9278  meter. 

The  highest  tide  observed  was  January  21 
and  w^as  1.3  ft.  above  mean  sea  level.  The 
lowest  tide  observed  was  ^lav  25  and  was  1.3 
ft.  below  mean  sea  level,  making  the  extreme 
range  2.6  ft.  The  mean  of  the  daily  highest 
water  elevations  was  0.47  ft.  above  mean  sea 
level.  The  mean  of  the  dailv  lowest  water  ele- 
vations  was  0.32  ft.  below  mean  sea  level. 


APPENDIX  IX.— REPORT  ON  PRECISE  LEVELS 


443 


CAR/BBE/I/^ 


Precise  Le/ef  Bench 
N9Z 


PRECISE  LEVEL  BENCH 
N9  I 
0  1000  tooo 


CANAi^ 


PRECISE  LEVEL  BENCH  Xo.  1. 

Mean  Kle\'ation  alK)ve  Sea  Level. 

Temporary  Bench  No.  1 7911  m.  2.595  ft. 

Peniianciit  Bench  Xo.  1,  on  glass 9278  m.  3.044  ft 

Permanent  Bench  Xo.  1,  on  cement 907G  m.  2.978  ft. 

IiiBtninient  \o.  J.  Instrument  No.  3. 

Temporary  Bench  No.  1 7910  m.  2.595  ft.  .7911  m.  2.595  ft. 

Permanent  Bench  No.  1,  on  glass 9278  m.  3.044  ft.  .9278  m.  3.044  ft. 

Permanent  Bench  No.  1,  on  cement 9062  m.  2.973  ft.  .9089  m.  2.982  ft. 


The  first  permanent  bench  was  put  In  150  feet 
southwest  of  the  tide  gage,  opposite  the  Canal  Com- 
pany's buildings  at  La  Fe,  at  the  west  end  of  Grey- 
town  harbor. 

Its  location  is  marked  in  the  accompanying  sketch 
by  the  heavy  black  circle  surrounding  a  smaller  circle. 

Temporary  bench  No.  1  is  23  feet  north  of  the  per- 
manent bench,  and  is  a  railroad  spike  driven  in  a 
wooden  pile  sunk  level  with  the  surrounding  beach. 
It  was  placed  January  6th,  1898. 

Permanent  bench  No.  1  is  a  glass  telegraph  insula- 


tor set  in  a  mass  of  cement  mortar,  36  inches  in 
diameter  and  20  inches  in  depth.  "  B.  M.  No.  1  N. 
C.  C.  1897-8  "  was  marked  on  the  mortar.  The  top 
of  the  insulator  was  level  with  the  surrounding 
beach,  and  was  covered  with  a  mound  of  driftwood 
and  sand.  Permanent  bench  No.  1  was  built  January 
10th,  1898.  Readings  were  taken  January  11th  on 
the  glass  insulator,  and  also  on  the  cement  mortar 
at  the  side  of  the  insulator. 

In  running  from  bench  No.  1  to  bench  No.  2  the 
backsights  were  read  first  by  both  Instruments. 


444 


NICARAGUA   CANAL  COMMISSION 


^ 

N 


NaiiwUhhMfmttsher  in 
foundafion  p/Je  of  plat  fori 


\ 


Oat^anizeef  spike  m         J  S 
bkaconfreeZ'aiam.    ""^i^ 


^Cotton  free 


Precise  Le^f    1/ 

Bench i^Z  \^    "^f^^P^ory  eench    PRECISE  LEVEL  BENCH 


ipr>        s%  Permanenf-  Bench 
^'^^f^j^fmac/gafree  /Z'^/ani        q 


\. 


NO  2 
100 


200 


SCALC 


PRECISE  LEVEL  BENCH  No.  2. 

Mean  Elevation  above  Sea  Level. 

Temporary  Bench  No.  2,  on  glass 1.7548  m.  5.757  ft. 

Temporary  Bench  No.  2,  on  cement 1.7439  m.  5.721  ft. 

Permanent  Bench  No.  2,  on  glass 1.6267  m.  5.337  ft. 

Permanent  Bench  No.  2,  on  cement 1.6029  m.  5.259  ft. 

Instrument  No.  1.  Instrument  No.  3. 

Temporary  Bench  No.  2,  on  glass 1.7519  m.  5.748  ft.  1.7676  m.  5.766  ft. 

Temporary  Bench  No.  2,  on  cement 1.7412  m.  5.713  ft.  1.7466  m.  5.730  ft. 

Permanent  Bench  No.  2,  on  glass 1.6241  m.  5.328  ft.  1.6293  m.  5.345  ft. 

Permanent  Bench  No.  2,  on  cement 1.5998  m.  5.249  ft.  1.6060  m.  5.269  ft. 


Bench  No.  2  is  0.9  of  a  mile  by  the  line  of  levels 
from  bench  No.  1,  and  is  the  main  bench  for  our  line 
of  levels.  Its  location  near  the  Canal  Company's 
buildings  at  La  F(^  is  shown  in  the  accompanying 
sketch. 

Temporary  bench  No.  2  is  a  glass  telegraph  insu- 
lator set  in  a  prism  of  concrete  mortar  12  inches 
square  and  24  inches  deep.  The  top  of  the  insulator 
is  level  with  the  top  of  the  surrounding  surface. 
Readings  were  taken  on  the  glass  insulator  and  on 
the  cement  mortar  at  the  side  of  the  insulator. 

Permanent  bench  No.  2  is  a  glass  telegraph  insu- 
lator, set  in  a  mass  of  cement  mortar  48  inches  in 
diameter  and  20  inches  deep.    The  top  of  the  insula- 


tor is  36  inches  below  the  surface.  The  bench  is 
covered  by  a  mound  of  earth.  **  B.  M.  No.  2,  N.  C.  C. 
1897-8  "  was  marked  on  the  mortar. 

This  bench  was  built  January  11th,  1898.  Read- 
ings were  taken  on  the  glass  insulator  and  on  the 
cement  mortar  at  the  side  of  the  insulator,  January 
12th  for  instrument  No.  1,  and  January  15th  for 
instrument  No.  3. 

With  instrument  No.  1  we  ran  from  the  Canal  Com- 
pany's bench  in  the  machine  shop  to  bench  No.  2, 
reading  backsights  first.  With  instrument  No.  3  we 
ran  from  bench  No.  2  to  the  Canal  Company's  bench 
in  the  machine  shop,  reading  backsights  first. 


APPENDIX  IX.— REPORT   ON   PRECISE   LEVELS 


445 


r 

N 


^"^^^Al^Sk:!^    <^ANAL  COMPANYlS  BENCH 
Bench  m  M^neSh^  ^^^^  GREYTOWN 


too 


400 


«4 


^<r> 


>. 


'^A. 


CANAL  CO.'S  BENCH  IN  MACHINE  SHOP. 


Canal  Co.'s  Bench  in  Machine  Shop 


Meuii  Eli>vatlon  al>ovo  Sea  Level. 

1.5417  m.  5.058  ft. 


Canal  Company's  Bench  in  Machine  Shop 


Instrument  Xo.  I, 
1.5374  m.  5.044  ft. 


InHtrument  No.  3. 
1.5459  m.  5.072  ft. 


The  Canal  Company's  main  bench  is  in  their  ma- 
chine shop,  about  a  mile  west  of  Greytown,  where 
their  canal  enters  Greytown  harbor,  and  is  0.7  of  a 
mile  from  our  bench  No.  2.  "  B.  M.  +  4.538  "  is  cut 
in  a  movable  board  of  the  machine  shop  floor,  under 
which  is  a  copper  point  set  in  masonry,  to  which  is 
attached  a  sheet  copper  tag  marked  "  -\-  4.538."  This 
elevation  gives  the  height  of  the  bench  above  mean 
water  level  in  the  Greytown  lagoon  as  determined  by 
the  Canal  Company,  and  was  used  by  us  in  flnding 


the  fleld  elevations  of  the  benches  east  of  Lake  Nica- 
ragua. 

The  gagings  made  by  this  Commission  near  Grey- 
town, and  our  corrected  level  line,  show  mean  sea 
level  to  be  .520  foot  below  the  Canal  Company's 
datum,  and  the  elevation  of  this  bench  to  be  as  given 
in  the  above  table. 

In  running  to  bench  No.  3  the  backsights  were 
read  flrst. 


446 


NICARAGl'A   CANAL  COMMISSION 


PRECI 


^    Precf'se  Le^  Bench 

^-         N93. 

-1- 


Temporary  Bench 
Nai/  inpbfg  S's^tfore 


lO 


PRECISK  LEVEL  J^EXC^II  No.  ;L 

Meun  El(>vation  alwivo  Si'u  Level. 

Temporary  Bench  Xo.  :i 4.(JS;J1)  ni.  L5.:ir)7  ft. 

rermanent  Bench  Xo.  3,  on  glass 0.8570  m.  22.4J)1)  ft. 

Permanent  Bench  Xo.  3,  on  cenu^nt (5.8352  ni.  22.425  ft. 

Instrument  No.  I.  Instrument  No.  3. 

Temporary  Bench  No.  3 4.6985  m.  15.415  ft.  4.6692  m.  15.319  ft. 

Permanent  Bench  No.  3,  on  glass 6.8715  m.  22.544  ft.  6.8436  m.  22.453  ft. 

Permanent  Bench  No.  3,  on  cement 6.8491  m.  22.471  ft.  6.8212  m.  22.379  ft. 


Bench  No.  3  is  4.4  miles  from  the  Canal  Company's 
bench  near  Greytown.  It  is  at  the  side  of  the  canal 
railroad,  near  the  junction  of  the  San  Juanillo  and 
the  Deseado  rivers. 

Temporary  bench  No.  3  is  a  nail  driven  in  a  three- 
inch  square  plug  at  the  right  side  of  the  track  at 
station  232  -^  47. 

Permanent  bench  No.  3  is  40  feet  northwest  of  the 
temporary  bench,  and  is  a  glass  telegraph  insulator 
set  in  a  mass  of  cement  mortar  marked  **  B.  M.  No.  3, 
N.  C.  C.  1897-8."  The  top  of  the  insulator  is  30  inches 
below  the  surface.  This  bench  was  made  January 
15th  and  the  elevation  taken  on  the  glass  insulator 
and  on  the  cement  mortar  at  the  side  of  the  insulator, 


by  instrument  No.  1,  January  17th,  and  by  instru- 
ment No.  3,  January  18th. 

The  difference  between  the  two  level  lines  at  a 
point  Just  west  of  the  Canal  Company's  bench  exceeds 
the  limit  allowed  of  0.03  foot  into  the  square  root  of 
the  number  of  miles  run  by  one  level,  and  this  part 
of  the  line  would  have  been  re-run  had  there  not  been 
an  error  in  the  calculated  field  elevations  in  the  notes 
for  instrument  No.  3,  which  was  not  corrected  till  the 
work  was  gone  over  in  Washington,  and  which  made 
the  elevations  appear  to  be  keeping  together. 

From  bench  No.  3  to  bench  No.  4  the  backsights 
were  read  first. 


APPENDIX  IX.— REPORT  ON  PRECISE  LEVELS 


447 


PKPXUSE  LEVEL  JJE.XCH  No.  4. 

Mean  Elevation  above  Sea  Level. 

Temporary  Bench  "So.  -i 7.1488  m.  23.454  ft. 

Pennaiieiit  Beiicli  Xo.  4,  on  glass 7.58(15  m.  24.890  ft. 

Permanent  Bench  Xo.  4,  on  cement 7.5705  m.  24.838  ft. 

Instrument  No.  1.  Instrument  No.  3. 

Temporary  Bench  No.  4 7.1540  m.  23.471  ft.  7.1435  m.  23.437  ft. 

Permanent  Bench  No.  4,  on  glass 7.5936  m.  24.913  ft.  7.5793  m.  24.866  ft 

Permanent  Bench  No.  4,  on  cement 7.5779  m.  24.862  ft.  7.5630  m.  24.813  ft. 


Bench  No.  4  is  5.5  miles  beyond  bench  No.  3.  and 
half  a  mile  east  of  the  Canal  Company's  location  for 
their  No.  1  lock. 

Temporary  bench  No.  4  is  a  railroad  spike  in  the 
center  of  the  track  in  a  tie  at  station  524  -|-  10. 

Permanent  bench  No.  4  is  a  glass  telegraph  insula- 
tor set  in  a  mass  of  cement  mortar  30  inches  below 
the  surface.      It  is  22   feet  to  the  right  of  station 


525  -f-  28.  "  B.  M.  No.  4  N.  C.  C.  1897-8  "  is  marked 
in  the  cement.  The  bench  was  built  January  21st, 
1898,  and  elevations  taken  on  the  glass  insulator  and 
on  the  mortar  at  the  side  of  the  insulator,  by  instru- 
ment No.  1,  January  24th,  and  by  instrument  No.  3, 
January  26th. 

From  bench  No.  4  to  bench  No.  5  the  backsights 
were  read  first. 


448 


NICARAGUA  CANAL  COMMISSION 


PKECISE  LEVEL  BENCH  No.  5. 

Mean  Elevation  above  Sea  Level. 

Temporary  Bench  No.  5 27.9598  m.  91.731  ft. 

Permanent  Bench  Xo.  5,  on  glass 28.7602  m.  94.357  ft. 

Permanent  Bench  No.  5,  on  cement 28.7276  m.  94.250  ft. 

Instrument  No.  1.  Instrument  No.  3. 

Temporary  Bench  No.  5 27.9612  m.  91.736  ft.  27.9584  m.  91.727  ft. 

Permanent  Bench  No.  5,  on  glass 28.7628  m.  94.366  ft.  28.7576  m.  94.349  ft. 

Permanent  Bench  No.  5,  on  cement 28.7298  m.  94.258  ft.  28.7254  m.  94.243  ft. 


Bench  No.  5  is  2.3  miles  by  our  line  of  levels  be- 
yond bench  No.  4,  and  is  just  west  of  the  Canal  Com- 
pany's location  for  their  No.  2  lock. 

Temporary  bench  No.  5  is  a  nail  in  the  root  of  an 
almendro  or  ebo  tree,  3  feet  in  diameter.  The  bench 
is  18  inches  above  the  ground. 

Permanent  bench  No.  5  is  a  glass  telegraph  insula- 
tor  set  in  a  mass  of  cement  mortar  30  inches  below 
the  surface.  "  B.  M.  No.  5  N.  C.  C.  1897-8  "  is  marked 
on  the  mortar. 


This  bench  was  made  February  1st  and  elevations 
were  taken  on  the  glass  insulator  and  on  the  cement 
mortar  by  the  side  of  the  insulator,  by  instrument 
No.  1,  February  9th  and  by  instrument  No.  3  Feb- 
ruary 7th. 

From  bench  No.  5  to  bench  No.  6  backsights  were 
read  first  by  both  instruments. 


APPENDIX  IX.— REPORT  ON  PRECISE  LEVELS 


449 


PRECISE  LEVEL  BENCH  No.  6. 

Mean  Elevation  above  Sea  Level. 

Temporary  Bench  No.  6 38.4384  m.  126.110  ft. 

Permanent  Bench  No.  6,  on  glass 37.4092  m.  122.733  ft. 

Permanent  Bench  No.  6,  on  cement •.*. 37.3814  m.  122.642  ft. 

Canal  Co.'s  Bench 18.0288  m.  59.149  ft. 

Instrument  No.  1.  Instrument  No.  8. 

Temporary  Bench  No.  6 38.4332  m.  126.093  ft.  38.4436  m.  126.127  ft. 

Permanent  Bench  No.  6,  on  glass 37.4040  m.  122.716  ft.  37.4143  m.  122.750  ft. 

Permanent  Bench  No.  6,  on  cement 37.3764  m.  122.626  ft.  37.3863  m.  122.658  ft. 

Canal  Company's  Bench  18.0262  m.  59.141  ft.  18.0313  m.  59.158  ft. 

Bench  No.  6  Is  5.2  miles  by  the  level  line  and  4.2  About  1500  feet  northeast  of  our  bench  is  an  old 

miles  measuring  along  the  Canal  Company's  center  Canal  Company's  bench,  recorded  in  their  notes  as 

line  of  the  canal  from  bench  No.  5.    It  is  just  east  of  **  No.  34  Molinas  check  levels,  Camp  Warner  Miller, 

the  Canal  Company's  location  for  their  No.  3  lock.  20  feet  left  Sta.  845,  Elevation  58.42  feet."  This  bench 

Temporary  bench  No.  6  is  a  nail  in  the  root  of  a  is  a  copper  bolt  in  the  root  of  a  tree  near  the  water's 

fiweetwood  tree  12  inches  in  diameter.  edge,  Just  above  Camp  Warner  Miller. 

Permanent  bench  No.  6  is  a  glass  telegraph  insula-  From  bench  No.  6  to  bench  No.  7  backsights  were 

tor  set  in  a  mass  of  cement  mortar.    The  insulator  read  first  by  instrument'  No.  1  and  foresights  first  by 

is  24  inches  below  the  surface  and  is  covered  by  a  instrument  No.  3. 

mound  of  earth.    "  B.  M.  No.  6  N.  C.  C.  1897-8  "  is  Our  line  west  of  bench  No.  6  passed  over  the  divide 

marked  in  the  cement  mortar.  1500  feet  north  of  the  Canal  "Company's  center  line 

This  bench  was  made  March  12th,  1898,  and  eleva-  for  the  canal,  following  their  railroad  line,  and  the 

tions  were  taken  on  the  glass  insulator  and  on  the  maximum  elevation  was  298.75  feet, 
cement  mortar  by  the  side  of  the  insulator,  March 
14th. 

29 


450 


NICARAGUA  CANAL  COMMISSION 


t      Ttmporary  Bench  NSl  Nori/in  rootof        \ 
N   BullY  free  3'ahm  Naff  is  ffa^foyefhe^nwna   "% 


^h^rmanoTf  Bencfi    x. 
Afmencfro free.  "^^NQl     ^  % 

J'akfm.e'soufhofffne  ^<^^.  ^  ^ 


^^ 


LEVEL  BENCH 
NOT 

400  800 


PRECISE  LEVEL  BENCH  No.  7. 

Mean  Elevation  above  Sea  LeveL 

Temporary  Bench  No.  7 42.2976  m.  138.771  ft. 

Permanent  Bench  No.  7,  on  glass 41.1104  m.  134.876  ft. 

Permanent  Bench  No.  7,  on  cement 41.0707  m.  134.746  ft. 

Canal  Co.'s  Bench 30.3745  m.  99.654  ft. 

Spike  at  Chanchos  River  Crossing 16.0079  m.  52.519  ft. 

Instrument  No.  1.  Instrument  No.  8. 

Temporary  Bench  No.  7 42.3069  m.  138.802  ft.  42.2882  m.  138.741  ft. 

Permanent  Bench  No.  7,  on  glass 41.1188  m.         134.904  ft.  41.1019  m.         134.848  ft. 

Permanent  Bench  No.  7,  on  cement 41.0805  m.  134.778  ft.  41.0609  m.         134.714  ft. 

Canal  Company's  Bench 30.3844  m.  99.686  ft.  30.3645  m.  99.621  ft. 

Spike  at  Chanchos  River  Crossing 16.0088  m.  52.522  ft.  16.0070  m.  52.516  ft. 

Bench  No.  7  is  7.5  miles  by  our  level  line  and  4.4  700  feet  east  of  our  No.  7  bench  is  an  old  Canal 

miles  by  the  Canal  Company's  center  line  of  the  canal  Company's  bench,  recorded   in  their  notes  as  "  On 

from  bench  No.  6.  redwood  tree  14  inches  in  diameter  at  Sta.  139  -f-  68, 

Temporary  bench  No.  7  is  a  nail  in  the  root  of  a  Perez  Canal  Location,  Divide,  marked  XX,  copper  bolt, 

bully  tree  3  feet  in  diameter.    The  nail  is  12  inches  El.  09.727  ft. 

above  the  ground.  Jj »     The  tree  has  been  cut  down,  but  the 

Permanent  bench  No.  7  is  a  glass  telegraph  insula-  08.727  ft. 

tor  set  in  a  mass  of  cement  mortar.    The  insulator  copper  bolt  is  in  the  stump  of  tree  in  the  telegraph 

is  24  inches  below  the  surface.    "  B.  M.  No.  7  N.  C.  C.  clearing. 

1897-8  "  is  marked  on  the  cement.    This  bench  was  From  bench  No.  7  to  bench  No.  8  backsights  were 

made  March  23d  and  elevations  were  taken  on  the  read  first  by  both  instruments.    Where  the  canal  line 

Insulator,  and  on  the  cement  mortar  by  the  side  of  leaves  the  Chanchos,  we  have  made  a  bench  by  driv- 

the  insulator,  by  instrument  No.  1,  March  24th,  and  ing  a  spike  in  the  root  of  a  60-inch  tree  at  Trundle's 

by  instrument  No.  3,  March  25th.  station  1117  +  80  on  the  east  bank  of  the  river. 


APPENDIX  IX.— REPORT  ON   PRECISE   LEVELS 


451 


LEVEL  BENCH 
NQ8 

AOO  600 


Precise  Levef  Bench  N^8    g)r 
On  large  Almendro.  free  on  highest  point  of 
Mil.  Fiicd  off  spiim  §-''>' 4r  In  west  root, 

J 


PKECISE  LEVEL  BENCH  No.  8. 

Mean  Elevation  above  Sea  Level. 

Bench  No.  8 45.7774  m.  150.188  ft. 

Kiver  gage  bench  near  Camp  Chanchos 15.8135  m.  51.881  ft. 

Kiver  gage  bench  near  Camp  Frisco 15.7180  m.  51.568  ft. 

Instrument  No.  1.  Instrument  No.  13. 

Bench  No.  8 45.7767  m.  150.186  ft.  45.7780  m.  150.190  ft 

River  gage  bench  near  Camp  Chanchos 15.8144  m.  51.884  ft.  15.8125  m.  51.878  ft. 

River  gage  bench  near  Camp  Frisco 15.7195  m.  51.573  ft  15.7165  m.  51.563  ft. 


Bench  No.  8  is  three  miles  by  our  level  line,  and 
two  miles  by  the  Canal  Company's  center  line  of  the 
canal,  beyond  bench  No.  7.  It  is  a  filed-oft  spike 
%  X  ^  inch  in  the  west  root  of  a  large  almendro 
tree  on  the  top  of  a  hill  Just  west  of  where  the  tele- 
graph line  last  crosses  the  Chanchos.  It  was  driven 
April  2nd,  1898,  and  readings  were  taken  by  instru- 
ment No.  1,  April  12th,  and  by  instrument  No.  3, 
April  2nd. 

A  river  gage  was  placed  by  the  hydrographic  party 
on  the  Chanchos  river  about  half  a  mile  above  the 
telegraph  crossing  and  near  Camp  Chanchos,  and 
a  bench  was  made  by  them  and  connected  with  the 
gage  rod.  Our  readings  on  this  bench  are  given 
above. 


On  the  San  Francisco  river,  Just  below  the  tele- 
graph crossing,  and  near  Camp  Frisco,  there  is  a 
gage  and  bench  placed  by  the  hydrographic  party, 
near  Trundle's  station  1250.  Our  readings  on  this 
bench  are  given  above. 

Our  line  between  benches  No.  8  and  No.  9  followed 
the  San  Francisco  river  to  the  San  FVancisco  tele- 
graph crossing  and  then  followed  the  Cailo  Surprise 
to  the  Danta  river,  and  the  Danta  to  the  Danta  tele- 
graph crossing. 

From  bench  No.  8  to  bench  No.  9,  backsights  were 
read  first  by  instrument  No.  1  and  foresights  first  by 
instrument  No.  3. 


452 


NICARAGUA  CANAL  COMMISSION 


nORlDA     LAGOON 


PRECISE  LEVEL  BENCH  No.  9, 


Bench  No.  9 


Mean  Elevation  above  Sea  Level. 

36.7239  m.  120.485  ft 


Bench  No.  9. 


Instrument  No.  1. 
36.7274  m.  120.497  ft. 


Instrument  No.  3. 
36.7204  m.  120.474  ft 


Bench  No.  9  is  7  miles  by  our  level  line,  and  5 
miles  by  the  Canal  Company's  center  line  of  the 
canal  beyond  bench  No.  8.  It  Is  on  top  of  a  hill  on 
the  south  side  of  the  Danta  river,  and  is  235  feet  east 
of  the  telegraph  line.  This  bench  is  a  lOd.  gal- 
vanized iron  nail  in  the  root  of  a  wild  tamarind  tree, 


driven  April  28th,  1898.    Readings  were  taken  April 
29th. 

The  line  between  benches  No.  9  and*  No.  10  follows 
the  telegraph  line.  Backsights  were  read  first  by 
both  instruments. 


APPENDIX   IX.— REPORT  ON   PRECISE   LEVELS 


453 


,oo 


y^ana  Propbsea  ^. 


y  T^^mpprary  Bench^  N^  /O.  dalvartizegd  'naif  In 


y  T^/^aranh  nnf^  nn     nOn^  SoufhvmsTy  root  of  j4/mencfro  "free  tinif/am. 

J^f^^'f^ST<  iSlftv^    Bench irt^oifefhe^nwna.  Trw marked 
highest po,ntofline-^c,b^  ^jffjfg'J;^  ^ 

y^/menOvtree-H'^^Oc^  Permanent ^nUr  /^fOjs  /0'S6(rv^ 

from  the  femporarry  bench 
Ocfioa  Camp 

^^Ha  DO^\\.^'^^^^^^^h)n'\wod  tree.  3'^'am.  and  i 5' from  water 

6'jpffce  arrVen  in  North  root  for  bench. 


/kN 


J 


UA^ 


PRECISE 


LEVEL  BENCH 
NQIO 

400  800 

SCAl-C 


PRECISE  LEVEL  liENCH  No.  10. 

Mean  Ele\^tloii  above  Sea  Level. 

Temporary  Bench  No.  10 39.4737  m.  129.507  ft. 

Permanent  Bench  No.  10,  on  spike 38.6851  m.  126.919  ft. 

Permanent  Bench  No.  10,  on  stone 38.6766  m.  126.892  ft. 

Spike  in  Cottonwood  at  Ochoa 20.8305  m.  68.341  ft. 

Bench  oppo^iite  Ochoa  Hydrographic  Camp 21.8674  m.  71.743  ft. 

Instrument  No.  1.  Instrument  No.  8. 

Temporary  Bench  No.  10 39.4761  m.  129.515  ft.  39.4712  m.  129.498  ft 

Permanent  Bench  No.  10,  on  spike 38.6873  m.  126.927  ft  38.6829  m.  126.912  ft 

Permanent  Bench  No.  10,  on  stone 38.6792  m.  126.900  ft  38.6740  m.  126.883  ft 

Spike  in  Cottonwood  at  Ochoa 20.8308  m.  68.342  ft  20.8302  m.  68.341  ft 

Bench  opposite  Ochoa  Hydrographic  Camp 21.8685  m.  71.747  ft  21.8663  m.  71.740  ft 

Bench  No.  10  is  5.7  miles  by  our  level  line,  and  4.5  We  expected   to   find  an   old   bench   in   the   large 

miles   by   the   Canal  Company's   center   line   of  the  cottonwood  tree  at  Ochoa  near  the  telegraph  station, 

canal,  beyond  bench  No.  9.  and  have  driven  a  6-inch  spike  in  the  north  root  of 

Temporary  bench   No.   10   is   a   galvanized   8-inch  this  tree,  the  elevation  of  which  is  given  above, 

spike  In  the  southwest  root  of  an  almendro  tree,  2  We  made  a  bench  by  driving  a  nail  in  the  root  of 

feet  in  diameter.    The  bench  is  18  inches  above  the  a  leaning  almendro  tree  on  the  north  bank  of  the 

ground.    The  tree  is  marked  with  an  18-inch  square  San  Juan  river  opposite  the  Ochoa  hydrographic  camp 

blaze.  and  15  feet  left  of  Trundle's  station  1678  -f  20. 

Permanent  bench  No.  10  is  a  spike  set  with  sulphur  The  line  between  benches  No.  10  and  No.  11  follows 

in  a  stone  buried  3  feet  below  the  surface,  10  feet  the  north  bank  of  the  river.    Backsights  were  read 

southwest  of  the  temporary  bench.    "  B.  M.  No.  10  first   by    instrument   No.   1   and    foresights   first   by 

N.  C.  C.  1898  '*  is  cut  in  the  stone.    This  bench  was  instrument  No.  3. 
made  May  18th,  and  elevations  were  taken  on  the 
spike  and  on  the  stone  at  the  side  of  the  spike.  May 
26th. 


454 


NICARAGUA  CANAL  COMMISSION 


Stuarts  Sta.39?  ana  Benc^maae 
May  26  1898.  Nat/  in  roof-of  5ay/7a/7 


Spf'ke  In  soafh  roofofSoTgnBgac/o  free 
3'cf/am  300'nor^  of  small sfnsam. 


N 


PRECISE  LEVEL  BENCH 
NSII 

O  fOOO  tOOO  3000 


PRECISE  LEVEL  BENCH  No.  11. 

Mean  Elevation  above  Sea  Level. 

Bench  No.  11 22.7615  m.  74.677  ft. 

Spike  in  root  of  Sangregado  tree 21.4222  m.  70.283  ft. 

Bench  near  Stuart's  Sta.  592 * 20.6303  m.  67.685  ft. 

Instrument  No.  1.  Instrument  No.  8. 

Bench  No.  11 22.7584  m.  74.667  ft.  22.7646  m.  74.687  ft. 

Spike  in  root  of  Sangregado  tree 21.4149  m.  70.259  ft.  21.4294  m.  70.306  ft. 

Bench  near  Stuart's  Station  592 20.6238  m.  67.663  ft.  20.6368  m.  67.706  ft. 


Bench  No.  11  is  3.7  miles  by  our  level  line  beyond 
bench  No.  10,  and  is  on  the  north  bank  of  the  San 
Juan  near  the  telegraph  station,  and  is  opposite  the 
mouth  of  the  San  Carlos  river.  This  bench  is  a  spike 
in  the  north  root  of  a  gavilan  tree,  3  feet  in  diameter, 
and  is  200'  N.  75"  W.  from  Thomas  Rodriga's  house, 
in  which  is  the  telegraph  station.  This  bench  was 
made  May  17th  and  readings  taken  May  17th  by  in- 
strument No.  1  and  May  23rd  by  instrument  No.  3. 

From  this  bench  our  line  runs  in  a  northwesterly 
direction  till  we  meet  the  river  again.  Our  maximum 
elevation  on  this  cut-off  was  178.7  feet. 


When  we  reached  the  river  again  we  made  a  bench 
by  driving  a  spike  in  the  south  root  of  a  sangregado 
tree,  and  1500  feet  farther  ahead  we  made  a  bench 
near  Stuart's  station  592,  by  driving  a  nail  in  the 
root  of  a  gavilan  tree.  From  this  point  to  bench  No. 
12  the  line  follows  the  north  bank  of  the  San  Juan 
river. 

Backsights  were  read  first  by  both  instruments  be- 
tween benches  No.  11  and  No.  12. 


APPENDIX  IX.— REPORT  ON   PRECISE   LEVELS 


455 


A  a.     RiO 


%^  Wood  Shea 
50 


L    Psrmaneni-  Bench  N9I2 

\%^  ^Temporary  Bench  NQI2 

6'splke  in  north  roof  of  6fvmp  of 
30* Tamarind  tree.  Sp/kcdn't/en 
9'abovegrouncl. 


PRECISE  LEVEL  BENCH 
NO  13 
0  400  800 

SCALE. 


PRECISE  LEVEL  BEXCII  No.  12. 

Mean  Elevation  above  Sea  Level. 

Temporary  Bench  No.  12 38.3969  m.  125.974  ft. 

Permanent  Bench  No.  12 ; 36.8054  m.  120.752  ft. 

Nail  in  Gavilan  tree 20.4302  m.  67.028  ft. 

Instrument  No.  1.  Tnstrument  No.  3. 

Temporary  Bench  No.  12 38.3968  m.  125.974  ft.  38.3969  m.  125.974  ft. 

Permanent  Bench  No.  12 36.8049  m.         .120.751  ft.  36.8058  m.  120.754  ft. 

Spike  in  Gavilan  tree 20.4323  m.  67.035  ft  20.4280  m.  67.021  ft 


Bench  No.  12  is  7  miles  by  our  line  beyond  bench 
No.  11.  It  is  in  a  large  clearing  near  Stuart's  station 
566. 

Temporary  bench  No.  12  is  a  6-inch  spike  in  the 
north  root  of  a  30-lnch  tamarind  tree.  This  bench  is 
9-inches  above  the  ground. 

Permanent  bench  No.  12  is  the  highest  point  of  a 
round  knob  cut  on  a  stone,  set  2  feet  below  the  sur- 
face,   7   feet   north   of   the   temporary    bench.    This 


bench  was  made  June  20th  and  elevations  were  taken 
on  it  by  instrument  No.  1  June  20th,  and  by  instru- 
ment No.  3  June  28th. 

173  feet  northwest  of  the  permanent  bench  is  a 
bench  made  by  driving  a  nail  in  the  north  root  of  a 
gavilan  tree,  25  feet  from  the  river. 

From  bench  No.  12  to  bench  No.  13  we  followed  the 
east  bank  of  the  San  Juan  river,  and  the  foresights 
were  read  first  by  both  instruments. 


456 


NICARAGUA  CANAL  COMMISSION 


5 


N 


Creek 


First  high  bluff  on  east  ^ank  of  San  Juan 
^ Mowihe  moulh  of  ihe  LaCruz,  cmddishmt 
"therefrom  460o'alonq1heielegraph  line 

H/drographical  and  F^rea'st  Level  Camps 


\ 


TtrrforcHy  Bench  N^i3.  Spikeofrivenineastroohf 

«. .        ,  ,.         ^    ^    .   Akmndrolhee  I'oiam,  Spikedrfven  IS' a^O¥e ground. 
Telcgn^ linemen^ shack ^    ^  ^,^   {^Telegraph  linemenls Shack 

Pgrmanenf  Bench  Nil3     \o 
lO'eastofthe  femporarv  bench\  ^  M copper Mfmmstniof of Almenoro 

\  \  free  3  mdamefer.  Bolt  Zatnve  ground 

Creek    \      •     go'STOEfhorhlemporary  tench. 

PRECISE  LEVEL  BENCH 
NO  13 

0  200  400 

SCALE 

Smfntp 


PRECISE  LEVEL  BENCH  No.  13. 

Mean  Elevation  above  Sea  Level. 

Temporary  Bench  No.  13 28.1253  m.  92.274  ft. 

Permanent  Bench  No.  13,  on  spike 27.1201  m.  88.977  ft 

Permanent  Bench  No.  13,  on  stone  at  side  of  spike 27.114:2  m.  88.957  ft. 

Old  copper  bolt 28.1126  m.  92.233  ft. 

Instrument  No.  1.  Instrument  No.  3. 

Temporary  Bench  No.  13 28.1292  m.  92.287  ft.  28.1214  m.  92.262  ft. 

Permanent  Bench  No.  13,  on  stone  at  aide  of  spike. .  27.1230  m.  88.986  ft.  27.1171  m.  88.967  ft. 

Permanent  Bench  No.  13,  on  stone  at  side  of  spike. .  27.1170  m.  88.966  ft.  27.1114  m.  88.948  ft. 

Old  copper  bolt 28.1169  m.  92.247  ft.  28.1082  m.  92.218  ft. 


Bench  No.  13  is  3.3  miles  by  our  line  beyond  bench 
No.  12,  and  is  on  the  first  high  bluff  on  the  east  bank 
of  the  San  Juan  river  below  the  mouth  of  the  La 
Cruz,  and  is  where  the  telegraph  line  again  meets  the 
river  after  leaving  it  at  Ochoa. 

Temporary  bench  No.  13  is  a  spike  in  the  east  root 
of  an  almendro  tree  in  the  center  of  the  clearing  for 
the  telegraph  shacks.  The  tree  is  2  feet  in  diamiter 
and  the  bench  is  18  inches  above  the  ground. 

Permanent  bench  No.  13  is  10  feet  east  of  the  tem- 
porary bench,  and  is  a  spike  leaded  in  a  stone  buried 
2  feet  below  the  surface.    This  bench  was  made  June 


2nd  and  readings  were  taken  on  the  spike,  and  on  the 
stone  at  the  side  of  the  spike,  by  instrument  No.  1 
June  29th,  by  instrument  No.  3  June  28th. 

Readings  were  also  taken  on  an  old  copper  bolt  in 
the  west  root  of  an  almendro  tree,  3  feet  in  diameter. 
This  bench  is  2  feet  above  the  ground  and  is  90'  S. 
70°  E.  from  the  temporary  bench.  It  was  made  by 
the  Canal  Company,  but  the  elevation  for  it  was  not 
worked  out  by  them. 

From  bench  No.  13  to  bench  No.  14  our  line  fol- 
lowed the  north  bank  of  the  river,  and  backsights 
were  read  first  by  both  instruments. 


APPENDIX  IX.— REPORT  ON  PRECISE  LEVELS 


457 


PEECISE  LEVEL  BENCH  No.  14. 

Mean  Elevation  above  Sea  Level. 

Temporary  Bench  No.  14 41.7639  m.  137.020  ft. 

Permanent  Bench  No.  14 40.8164  m.  133.912  ft. 

Nail  in  Gavilan  tree '. 25.3173  m.  83.062  ft. 

Nail  in  Jobo  tree  above  Machuca  river 23.5970  m.  77.418  ft. 

Nail  in  stump,  Agiia  Fresca  river 24.5995  m.  80.707  ft. 

Instrument  No.  1.  Instrument  No.  8. 

Temporary  Bench  No.  14 41.7624  m.  137.015  ft.  41.7653  m.  137.025  ft. 

Permanent  Bench  No.  14 40.8147  m.  133.906  ft.  40.8181  m.  133.917  ft. 

Nail  in  Gavilan  tree  25.3170  m.  83.061  ft.  25.3176  m.  83.063  ft 

Nail  in  Jobo  tree  above  Machuca  river 23.5932  m.  77.405  ft.  23.6008  m.  77.430  ft 

Nail  in  stump,  Agua  Fresca  river 24.5969  m.  80.698  ft  24.6021  m.  80.716  ft 

Bench  No.  14  is  seven  miles  by  our  line  of  levels  by  instrument  No.  1  July  18th,  and  by  instrument  No. 

beyond  bench  No.  13,  and  is  half  a  mile  below  the  3  July  16th. 

mouth  of  the  Machuca  river.    It  is  at  a  point  of  rock  We  also  made  a  bench  90  feet  west  of  the  per- 

which  juts  out  into  the  river  just  above  Isla  Campaiia.  manent  bench  by  driving  a  nail  in  a  gavilan  tree. 

Temporary  bench  No.  14  is  an  8-inch  spike  driven  We  made  a  bench   1100   feet  above  the  Machuca 

in  the  east  root  of  a  ^gavilan  tree,  12  inches  above  the  river  and  70  feet  from  the  San  Juan  river,  by  driving 

ground.  a  nail  in  the  south  root  of  a  jobo  tree  18  inches  in 

Permanent  bench  No.  14  is  6%  feet  south  of  the  diameter, 

temporary  bench,  and  is  10  feet  west  of  a  sangregado  Wl\ere  our  line  crosses  the  Agua  Fresca  river  we 

tree,  2  feet  in  diameter,  marked  by  a  blaze  1  foot  by  drove  a  nail  in  a  four-inch  stump  on  the  east  bank 

3  feet,  and  is  115  feet  from  the  river,  measuring  along  of  the  river  for  a  bench. 

Stuart's  cutting.    This  bench'  is  a  buried  stone,  on  From  bench  No.  14  to  bench  No.  15  our  line  fol- 

the  highest  point  of  which  elevations  were  taken.  lowed  the  north  bank  of  the  river  and  foresights  were 

The  bench  was  made  July  16th,  and  elevations  taken  read  first  by  both  instruments. 


458 


NICARAGUA  CANAL  COMMISSION 


PRECISE  LEVEL  BENCH  No.  15. 


Bench  No.  15 


Mean  EloMitlon  above  Sea  Level. 

27.3129  m.  89.609  ft. 


Bench  No.  15 


Instrument  No.  1. 
27.3127  m.  89.608  ft 


Instrument  No.  8. 
27.3131  m.  89.610  ft 


Bench  No.  15  Is  8.5  miles  by  our  line  beyond  bench 
No.  14,  and  is  at  the  mouth  of  the  Bartola  river. 

Bench  No.  15  is  a  6-inch  spike  in  the  west  root  of 
a  camibar  tree.  The  tree  is  2  feet  in  diameter,  20 
feet  above  the  ground.  The  spike  is  driven  18  inches 
above  the  ground  and  18  inches  from  the  body  of  the 


tree.  The  tree  is  marked  by  a  blaze  2  feet  square. 
The  bench  was  made  and  the  readings  were  taken 
August  2nd. 

From  bench  No.  15  to  bench  No.  16  our  line  follows 
the  north  bank  of  the  river,  and  the  backsights  were 
read  first  by  both  instruments. 


APPENDIX   DC—REPORT  ON   PRECISE   LEVELS 


469 


N 


PRECISE  LEVEL.  BENCH 

N9  16 

o  AOO  &)0 


RIO 


Temporary  Bench  NQ  Id  /5  6'sf^'ke/n  soMroaf-  of  a 
Oi/aya  tree,  and  is  ff'alwye  the  grouncf.  l^^^^V 

aoo!^  ^  ^   >^if/777^/7^/  Bench N9  16 
Sxj  A  .  \    --^^dw    s\   SSoyto center  of 


A/ 


yy. 


O. 


^ 


> 


CASTILLO 


o 

VA 


'=nn 


•$\  hi^esfparfoffirt. 


PRECISE  LEVEL  BENCH  No.  16. 

Mean  BlevBtion  above  Sea  Level. 

Temporary  Bench  No.  16 31.4841  m.  103.294  ft. 

Permanent  Bench  No.  16,  on  spike 39.4701  m.  129.495  ft. 

Permanent  Bench  No.  16,  on  stone 39.4611  m.  129.465  ft. 

Bench  near  Stuart's  Sta.  210 29.8021  m.  97.776  ft. 

Instrument  No.  1.  Instrument  No.  3. 

Temporary  Bench  No.  16 31.4789  m.  103.277  ft.  31.4892  m.  103.311  ft 

Permanent  Bench  No.  16,  on  spike 39.4639  m.  129.474  ft.  39.4762  m.  129.515  ft 

Permanent  Bench  No.  16,  on  stone 39.4549  m.  129.445  ft  39.4672  m.  129.485  ft 

Bench  near  Stuart's  Station  210 29.7964  m.  97.757  ft  29.8077  m.  97.794  ft 


Bench  No.  16  is  5.7  miles  by  our  line  beyond  bench 
No.  15,  and  is  opposite  Castillo. 

Temporary  bench  No.  16  is  a  6-inch  spike  in  the 
south  root  of  a  guava  tree,  and  is  6  inches  above  the 
ground. 

Permanent  bench  No.  16  is  a  spike  set  with  sulphur 
in  a  stone  buried  2  feet  below  the  surface,  and  is 
110  feet  S.  75°  E.  from  the  temporary  bench.  This 
bench  was  made  August  3rd,  and  elevations  were 
taken  on  the  spike,  and  on  the  stone  at  the  side  of 
the  spike,  by  instrument  No.  1  August  12th  and  by 
instrument  No.  3  August  9th. 


300  feet  west  of  Stuart's  station  210  we  made  a 
bench  by  driving  a  6-inch  spike  in  the  north  root  of 
a  culebra  tree  6  inches  in  diameter. 

Our  line  from  bench  No.  16  to  bench  No.  17  follows 
the  north  bank  of  the  river  to  Stuart's  station  210, 
and  then  follows  very  closely  the  line  of  his  cut-off, 
west  till  it  meets  the  river  again. 

In  passing  over  this  ground  our  maximum  eleva- 
tion was  127.2  feet 

Between  bench  No.  16  and  bench  No.  17  backsights 
were  read  first  by  instrument  No.  1  and  foresights 
first  by  instrument  No.  3. 


460 


NICARAGUA  CANAL  COMMISSION 


's  tfenc/t  tiait  in 
norlh  east  root  cf 
MotreeS'cAam, 


PRECISE  L-E.VEL  BENCH 

NO|7 
0  400  SOO 


N 


j^RBrrnufient  Benotr 

TdmpararySefTC/tN^fl/sBipfMsaimninifresoafheastroffto^a^  ^^/^ 
6ua^0iree  aflhe  surface  of -ffiegnund.  The  free  hdMth.  The  me^fitirtisZ'/n  a/am. 
The  east  is  18*.  The^'ke  Is  in  Ihe  east  part.  Theivoeis  5o' -fivnthehifi^ one/ ^^  east  end 
of  ihe  faithil/  bekmf  Ihe  t^io  Sora/os, 


PRECISE  LEVEL  BENCH  No.  17. 

Mean  Elovation  above  Sea  Level. 

Temporary  Bench  No.  17 31.1376  m.  102.157  ft. 

Permanent  Bench  No.  17,  on  spike 41.6057  m.  136.501  ft. 

Permanent  Bench  No.  17,  highest  part  stone 41.5967  m.  136.472  ft 

Stuart's  Bench  on  west  bank  of  Savalos 31.6087  m.  103.703  ft. 

6"  spike  in  Chapema  tree,  Eio  Negro 31.7032  m.  104.013  ft. 

Instrumont  No.  1.  Instrument  No.  «3. 

Temporary  Bench  No.  17 31.1335  m.          102.144  ft           31.1416  m.  102.170  ft. 

Permanent  Bench  No.  17,  on  spike 41.6009  m.          136.486  ft.           41.6104  m.  136.517  ft 

Permanent  Bench  No.  17,  highest  part  stone 41.5919  m.          136.456  ft           41.6014  m.  136.487  ft 

Stuart's  Bench  on  west  bank  of  Savalos 31.6030  m.          103.684  ft           31.6143  m.  103.721  ft. 

6-inch  spike  in  Chapema  tree,  Rio  Negro 31.7002  m.          104.003  ft           31.7061  m.  104.022  ft. 


Bench  No.  17  is  7.2  miles  by  our  line  beyoi^d  bench 
No.  16,  and  is  on  the  first  hill  below  the  Savalos 
river. 

Temporary  bench  No.  17  is  a  6-inch  spike  driven  in 
the  southeast  root  of  a  guava  tree,  50  feet  from  the 
river,  and  at  the  east  end  of  the  hill. 

Permanent  bench  No.  17  is  71  feet  N.  20°  E.  from 
the  temporary  bench.  It  is  a  spike  set  with  sulphur 
in  a  stone  buried  12  inches  below  the  surface.  Eleva- 
tions were  taken  on  the  spike  and  on  the  highest 
part  of  the  stone.  This  bench  was  made  August  19th, 
and  elevations  were  taken  by  instrument  No.  1  Au- 
gust 26th,  and  by  instrument  No.  3  August  19. 

There  is  a  bench  made  by  Stuart's  party  on  the 


west  bank  of  the  Savalos  river,  20  feet  from  the  San 
Juan  river.  It  is  a  nail  in  the  northeast  root  of  a 
Jobo  tree,  3  feet  in  diameter,  and  is  12  inches  above 
the  ground. 

We  made  a  bench  on  the  west  bank  of  the  Rio 
Negro  about  500  feet  from  its  mouth  by  driving  a 
6-inch  spike  in  the  south  root  of  a  chaperna  tree,  12 
inches  above  the  ground.  The  tree  is  3  feet  in  diam- 
eter. 

From  bench  No.  16  to  bench  No.  17  our  line  is  from 
500  to  1000  feet  back  from  the  north  bank  of  the 
river.  Foresights  were  read  first  by  instrument  No. 
1  and  backsights  first  by  instrument  No.  3. 


APPENDIX  IX.— REPORT  ON  PRBCI8B  LEVELS 


461 


PRECISE  LEVEL  BENCH  No.  18. 

Mean  Elei'atlon  al 

Tempora:7  Bench  Ko.  18 36.4926  n 

Permanent  Bench  No.  18,  on  spike 36.9888  a 

Permanent  Beneli  No.  18,  on  stone 36.9629  n 

6"  spike  in  Jobo  tree,  Caiio  Ursula 31.8600  n 

6"  spike  in  Ojocha  tree,  Palo  de  Areo  Creek 32.7475  m. 

Instrument  No.  I. 

Permanent  Bench  No.  IS,  on  spike 36.9914  m.         121.363  ft  36.: 

e-lnch  spike  In  Ojocha  tree,  Palo  de  Arco  Creek 32.7503  m.  107.448  ft.  32: 


119.726  ft. 
121.354  ft. 
121.269  ft. 
104.527  ft 
107.439  ft. 

No.  3. 


Bench  No.  IS  Is  12.3  miles  bj  our  line  berond 
bench  No.  17,  and  Is  near  the  east  end  of  Stuart's 
cut-ofF  from  Isla  Grande  wesL 

Temporary  bench  No.  18  is  a  6-lDcb  spike,  12  Inches 
above  the  ground  In  the  northwest  root  ot  an  IS- 
Inch  diameter  mansano  tree,  marked  by  a  blaze  4 
feet  high  and  1  foot  wide. 

Permanent  bench  No.  IS  Is  a  spike  set  with  sulphur 
In  a  stone  burled  2  feet  below  the  surface,  17  feet 
west  of  the  temporary  bench.  This  bench  was  made 
September  13th  and  elevations  were  taken  on  the 
spike,  and  on  the  stone  at  the  west  side  of  the  spike, 
by  Instrument  No.  1  September  14th,  and  by  Instru- 
ment No.  3  September  13th. 

On  the  west  bank  of  the  CaQo  Ursula,  about  1000 


feet  from  the  San  Juan  river  and  1750  teet  above  the 
west  end  o(  Stuart's  cut-off,  we  made  a  bench  by 
driving  a  6-lnch  spike  In  the  northeast  root  o[  a  Jobo 
tree  3  teet  In  diameter.  This  bench  Is  12  Inches  above 
the  ground. 

125  leet  west  of  the  west  bank  of  the  Palo  de  Arco 
creek  and  2000  feet  from  the  San  Juan  river  we  made 
a  bench  by  driving  a  6-Inch  spike  In  the  south  root 
ol  an  ojocha  tree.  This  tree  is  3  feet  In  diameter  and 
has  large  spreading  roots.  The  bench  is  IE  Inches 
above  the  ground. 

Between  bench  No.  18  and  bench  No.  19  backsights 
were  read  first  by  Instrument  No.  1  and  foresights 
first  by  Instrument  No.  3. 


462 


NICARAGUA  CANAL  COMMISSION 


N 


PRECISE  LEVEL  BENCH 

N9  19 

0  200  400 


Temporvry  Bench  hPl9  Is  6^spikt  in  east  root 
3'abo^e  ihe  surface  of  ft'diam  Ouasimotree. 
anct  Is  id'norlhwest  of  ihe  Rsrmanent  Bench 


House  wrfhU^ 
corrugated  iron  roof       S 

I 

I 

JOHN   PETER'3  farm 


-gmife  from  Rio  SanJudn 


Permanent  Bench  N^t9 

/5'north  of  northeast  comer  of  house 


6spike  etri^en  6'aboi€^ 
^vund  in  north  root  of 
masimo  tree.  2'aiam. 


Chora 


PRECISE  LEVEL  BENCH  No.  19. 

Mean  Blevation  above  Sea  Level. 

Temporary  Bench  No.  19 39.8534  m.  130.762  ft. 

Permanent  Bench  No.  19,  on  spike 39.4572  m.  129.452  ft. 

Permanent  Bench  No.  19,  on  stone 39.4424  m.  129.404  ft. 

Spike  in  Gnasimo  tree,  Melchora  Eiver 32.3579  m.  106.161  ft 

Highest  part  of  stone,  Melchorito  Eiver 32.9975  m.  108.259  ft. 

6"  spike  near  Isla  Cano 32.1703  m.  105.545  ft. 

Stuart's  Bench  near  his  Sta.  No.  14 32.8219  m.  107.683  ft. 

Instrument  No.  1.  Instrument  No.  3. 

Permanent  Bench  No.  19,  on  spike 39.4580  m.  129.455  ft.  39.4564  m.         129.450  ft 

Stuart's  Bench  near  his  Station  No.  14 32.8225  m.  107.685  ft.  32.8213  m.  107.681  ft. 

Bench  No.  19  is  7.3  miles  beyond  bench  No.  18.  tree,  marked  by  a  blaze  12  inches  by  3  feet,  we  made 

Temporary  bench  No.  19  is  a  6-inch  spike  in  the  a  bench  by  cutting  a  3-inch  square  round  the  highest 

east  root,  3  inches  above  the  ground,  of  a  12-inch  part  of  a  large  rock, 

diameter  guasimo  tree.  2000  feet  west  of  the  east  end  of  Isla  Cailo,  on  the 

Permanent  bench  No.  19  is  a  spike  set  with  sulphur  west  bank  of  a  creek,  and  50  feet  from  the  San  Juan 

in   a  stone   buried   2   feet   below   the   surface.    This  river,  we  make  a  bench  by  driving  a  6-inch  spike  in 

bench  was  made  September  21st,  and  elevations  were  the  west  root,  2  feet  above  the  ground,  of  an  18-inch 

taken  on  the  spike  and  on  the  stone  at  the  side  of  diameter  popojonh  tree. 

the  spike  by  instrument  No.  1  September  23rd,  and  We  read  on  Stuart's  bench  75  feet  west  of  his  sta- 

by  instrument  No.  3  September  22nd.  tion  No.  14  on  the  north  root  of  a  2-foot  diameter 

600  feet  S.  40''  E.  from  the  permanent  bench,  we  chilati  tree  on  the  first  small  hill  on  the  north  bank 

made  a  bench  by  driving  a  spike  in  the  root  of  a  of  the  San  Juan  river,  below  Lake  Nicaragua, 

guasimo  tree  on  the  bank  of  the  Melchora  river.  Between  bench  No.  19  and  bench  No.  20  foresights 

500  feet  east  of  the  mouth  of  the  Melchorito  river,  were  read  first  by  instrument  No.  1  and  backsights 

at   the   base   of  a   hill   about   a   mile   west   of   the  first  by  instrument  No.  3. 
Melchora  river,  and  25  feet  west  of  an  18-inch  Jobo 


APPENDIX  IX.— REPORT  ON   PRECISE   LEVELS 


4G3 


Temporary  Bench  N920  is  center  of  ti  Square  catan  stone  set-f/usftrntlf 
grvuncl  4eas/-  of  Mi¥corof^rm(^anof.  ' 

f^rmanenf  Bench  N920is  brass pdnh 
set  Mfith  sufphurin  stone,  berieU  Z'bekmfie 
sarfyce  3'/^.\¥.oft/.W.CProfgrm^arvt. 


PRECISE  LEVEL  BENCH 
N9SO 

0  400 


Steamboat' 
tjin^ng 


RIO  SAN  JUAN 


PRECISE  LEVEL  BENCH  No.  20. 

Mean  Blevation  above  Sea  Level. 

Temporary  Bench  No.  20 50.0167  m.  164.096  ft 

Permanent  Bench  No.  20,  on  brass 49.0300  m.  160.859  ft 

Permanent  Bench  No.  20,  on  stone 49.0070  m.  160.784  ft. 

Canal  Co.'s  Bench  on  boiler  at  San  Carlos 33.3195  m.  109.316  ft 

13'  mark  on  gage  rod  at  boiler 33.3561  m.  109.436  ft 

Instrument  No.  1.  Instrument  No.  3. 

Temporary  Bench  No.  20 50.0129  m.          164.084  ft.            50.0205  m.  164.109  ft 

Permanent  Bench  No.  20,  on  brass 49.0261  m.         160.846  ft.           49.0339  m.  160.872  ft. 

Permanent  Bench  No.  20,  on  stone 49.0034  m.         160.772  ft           49.0105  m.  160.795  ft. 

Canal  Company's  Bench  on  boiler  at  San  Carlos 33.3197  m.          109.316  ft           33.3193  m.  109.315  ft. 

13-foot  mark  on  gage  rod  at  boiler 33.3549  m.          109.432  ft.            33.3572  m.  109.439  ft. 


Bench  No.  20  is  10.7  miles  by  our  line  beyond 
bench  No.  19,  and  is  at  the  northwest  corner  of  the 
graveyard  at  San  Carlos,  Lake  Nicaragua. 

Temporary  bench  No.  20  is  the  center  of  a  1%- 
inch  square  cut  on  a  stone  set  flush  with  the  ground, 
4  feet  east  of  the  northwest  corner  of  the  graveyard. 
Permanent  bench  No.  20  is  a  brass  point  set  with 
sulphur  in  a  stone  buried  2  feet  below  the  surface,  3 
feet  northwest  of  the  northwest  corner  of  the  grave- 
yard. 

Elevations  were  taken  on  the  brass  point  and  on 


the  center  of  a  2-inch  square  cut  in  the  stone  east 
of  the  brass  point.  The  stone  was  placed  October  3rd, 
1898,  and  the  elevations  were  taken  October  8th. 

There  is  a  Canal  Company's  bench,  a  cross  cut  on 
the  shore  end  of  an  old  steamboat  boiler  in  Lake 
Nicaragua,  southwest  of  our  bench  No.  20.  This  was 
the  initial  bench  for  Stuart's  levels. 

Southwest  of  this  bench  and  attached  to  the  iron- 
work of  the  old  steamboat  is  the  San  Carlos  lake 
gage. 


464 


NICARAGUA  CANAL  COMMISSION 


PRECISE 


6aff3»K^f/S2  Nalin6''5fifmp 

Bench  N9 I 

Geige  Bench  N^3.  /j^hes/-pofrjf\  ^ 

anokfc/fiinaerhead^Af'of  \ 

Aawf.  S'5Sl¥afSenc/fN9t     \ 

6age  Bench  U9/.  hi^eshpoint  on 

wesf'nm  aFoU  inn  cy Windier  i^ 

waterietfge. 


LEVEL.BENCH 
N9ai 

400  800 


4  LafmO^/^r 
\  0  MSfeamlfoaf-hotkr 
♦  lo^dageNQf. 


sc 


SCALC 


N 


Temporary  Bench  N9ZI  is  center  of  f 'Q 
cot  in  S.W.  corner  of  sfone  iS'squareond  iS' 
aifo^e  ground,  setoneeifeofblifffon  lake 
frvof  as  a  property  line  monument 


5 


OM  Bench  SZS'E  126' from  Mksri 

•^  5fa0,  Larqe  6al¥arfrzeainmsp/l(e 
in  roof  or  Rotflefrte  3*fn  diam. 
£1 112. 540  cut  in  tree  by  Walker. 


APPENDIX  IX.— REPORT  ON  PRECISE  LEVELS 


465 


PKECISE  LEVEL  BENCH  Ko.  21. 

Mean  Elevation  above  Sea  Level. 

Temporary  Bench  No.  21 37.4572  m.  122.891  ft. 

Permanent  Bench  No.  21,  on  spike 36.8077  m.  120.760  ft. 

Permanent  Bench  No.  21,  on  stone 36.7942  m.  120.716  ft. 

Lake  Gage  Bench  No.  1 33.1299  m.  108.694  ft. 

Lake  Gage  Bench  No.  2 34.5151  m.  113.238  ft. 

Lake  Gage  Bench  No.  3 34.3492  m.  112.694  ft. 

10'  mark,  gage  No.  I 32.9320  m.  108.044  ft. 

9'  mark,  gage  No.  II 31.4520  m.  103.189  ft 

Walker's  Bench  near  his  Sta.  0 34.2022  m.  112.212  ft. 

Mark  on  property  line  stone,  San  Pablo 39.7240  m.  130.328  ft. 

InBtrument  No.  1.  Instrument  No.  3. 

Temporary  Bench  No.  21 37.4534  m.          122.878  ft.            37.4610  m.  122.903  ft. 

Permanent  Bench  No.  21,  on  spike 36.8044  m.          120.749  ft.            36.8109  m.  120.770  ft. 

Permanent  Bench  No.  21,  on  stone 36.7904  m.          120.703  ft.           36.7979  m.  120.728  ft. 

Lake  Gage  Bench  No.  1 33.1271  m.          108.685  ft.         .   33.1326  m.  108.703  ft. 

Lake  Gage  Bench  No.  2 34.5122  m.          113.229  ft.            34.5180  m.  113.248  ft 

Lake  Gage  Bench  No.  3 34.3468  m.          112.686  ft.            34.3515  m.  112.702  ft 

10-foot  mark,  Gage  No.  1 32.9280  m.          108.031  ft            32.9359  m.  108.057  ft 

9-foot  mark.  Gage  No.  II 31.4508  m.          103.185  ft        '    31.4531  m.  103.192  ft 

Walker's  Bench  near  his  Station  0 34.1975  m.          112.196  ft            34.2069  m.  112.227  ft 

Mark  on  property  line  stone,  San  Pablo 39.7208  m.          130  317  ft            39.7271  m.  130.338  ft 


Bench  No.  21  is  on  the  west  shore  of  Lake  Nica- 
ragua near  the  mouth  of  the  Lajas  river,  and  is  on 
the  lake  end  of  the  Canal  Company's  north  property 
line,  and  1250  feet  from  the  center  line  of  the  canal. 

Temporary  bench  No.  21  is  the  center  of  a  2-inch 
square  cut  in  the  southwest  corner  of  a  stone  18 
inches  square  and  15  inches  above  ground,  set  on  the 
edge  of  the  bluff  on  the  lake  front  as  a  property  line 
monument 

Permanent  bench  No.  21  is  20  feet  southwest  of  the 
temporary  bench,  and  is  a  spike  set  with  sulphur  in 
a  stone  buried  18  inches  below  the  surface.  Eleva- 
tions, were  taken  on  the  spike,  and  on  the  center  of 
a  1^-inch  square  cut  in  the  stone  2  inches  northeast 
of  the  spike.  The  bench  was  made  October  20th  and 
readings  were  taken  by  instrument  No.  1  October 
22nd,  and  by  instrument  No.  3  October  21st. 

About  1200  feet  north  of  our  No.  21  bench  is  the 
Lajas  hydrographic  station.  There  are  at  this  sta- 
tion 3  benches  and  two  gage  rods  placed  to  ascer- 
tain the  height  of  the  lake.  Gage  bench  No.  1  is  the 
highest  point  on  the  west  rim  of  an  old  iron  cylinder 
at  the  water's  edge. 

Gage  bench  No.  2  is  about  63  feet  northwest  of 
gage  bench  No.  1,  and  is  a  nail  in  a  6-inch  stump  at 
the  foot  of  the  bank. 

Gage  bench  No.  3  is  5  feet  S.  S.  W.  of  gage  bench 
No.  2,  and  is  the  highest  point  on  an  old  cylinder 
head  at  the  foot  of  the  bank. 
30 


Lake  gage  No.  I  is  attached  to  the  ironwork  of  the 
old  steamboat,  south  of  the  boiler.  It  is  inclined  2 
inches  to  the  foot.  This  gage  is  used  in  reading  the 
water  during  the  high  stage  of  the  lake. 

Lake  gage  No.  II  is  attached  to  the  ironwork  of 
the  old  steamboat  north  of  the  boiler.  This  gage  is 
used  in  reading  the  water  during  the  low  stage  of 
the  lake. 

There  is  a  bench  on  the  lake  front  made  by  Mr. 
Walker,  126  feet  S.  23°  E.  from  his  station  0.  It  is 
a  galvanized  iron  spike  in  the  root  of  a  roble  tree  3 
feet  in  diameter.  The  elevation  112.540  feet  is  cut  in 
the  tree. 

We  made  a  bench  on  the  property  line  stone  near 
San  Pablo.  This  bench  is  the  center  of  a  square  cut 
in  the  east  corner  of  the  property  line  stone.  The 
stone  is  18  inches  square  and  is  12  inches  above  the 
ground.  It  is  on  the  south  side  of  the  road  from 
San  Pablo  to  Rivas,  and  is  1600  feet  from  San  Pablo. 

Our  line  from  bench  No.  21  to  bench  No.  22  follows 
approximately  the  Canal  Company's  north  property 
line  to  the  property  line  stone  at  San  Pablo,  and 
then  follows  the  Canal  Company's  center  line  of  the 
canal.  Our  maximum  elevation  west  of  the  lake  was 
158.8  feet 

Between  these  benches,  foresights  were  read  first 
by  instrument  No.  1,  and  backsights  by  instrument 
No.  3. 


466 


NICARAGUA  CANAL  COMMISSION 


Elevations  were  carried  across  the  lake  from 
San  Carlos  to  Las  Lajas  by  comparing  the  read- 
ings of  the  lake  gages  at  those  places. 

For  carrying  the  levels  across  the  lake,  we 
have  the  readings  of  the  gages  at  San  Carlos  and 
Las  Lajas  during  the  months  of  April,  May, 
Jnne,  July,  August  and  September.  At  San 
Carlos  there  was  one  gage  bolted  to  the  iron  work 
of  an  old  steamboat.  At  Las  Lajas  there  were 
two  gages  secured  to  the  iron  work  of  another 
old  steamboat  One  of  these,  gage  No.  I,  was 
read  during  the  high  water  from  April  1st  to 
May  21st,  and  from  July  16  to  September  29th. 
The  other,  gage  No.  II,  was  read  during  low 
water  from  May  1st  to  July  16th. 

Carrying  the  levels  across  the  lake,  using  gage 
No.  I  at  Las  Lajas,  we  find  the  average  height 
of  the  water  on  the  San  Carlos  gage  when  the 
readings  were  taken  on  the  No.  I  Las  Lajas  gage 
to  be  7.418  feet,  or  5.582  feet  below  the  13-foot 
mark,  and  the  average  reading  on  the  Las  Lajas 
No.  I  gage  for  the  same  time  to  be  5.880  feet, 
or  4.120  feet  measured  on  the  gage  from  the  10- 
foot  mark.  Gage  No.  1  at  Las  Lajas,  in  order 
that  it  might  be  more  securely  fastened  to  the 
boiler,  was  placed  at  an  inclination  of  2  inches 
to  the  foot,  and  reducing  4.120  feet  to  a  vertical 
distance,  it  becomes  4.062  feet. 

Assuming  the  average  surface  of  the  lake  to 
be  level,  this  shows  that  the  13-foot  mark  on  the 
San  Carlos  rod  was  1.520  feet  higher  than  the 
10-foot  mark  on  the  Las  Lajas  rod,  making  the 
elevation  of  the  lO-foOt  mark  107.916  feet,  and 
the  elevation  of  the  Las  Lajas  gage  bench  No.  I, 
108.566  feet. 

Comparing  the  readings  of  gage  No.  II  at 
Las  Lajas  and  the  San  Carlos  gage,  and  assuming 
the  average  surface  of  the  lake  to  be  level  while 
these  readings  were  taken,  we  find  the  average 


difference  between  the  readings  shows  the  zero 
of  the  No.  n  gage  to  be  2.247  feet  below  the 
zero  of  the  San  Carlos  gage,  and  the  elevation 
of  the  9-foot  mark  on  the  No.  11  Las  Lajas  gage 
to  be  103.189  feet,  and  the  elevation  of  the  Las 
Lajas  gage  bench  No.  I  to  be  108.694  feet. 

Taking  the  average  of  the  five  calm  days  se- 
lected by  Mr.  Davis  for  comparing  all  the  lake 
gages,  and  using  No.  II  gage  reading  at  Las 
Lajas,  gives  the  elevation  of  the  9-foot  mark 
103.233  feet,  and  of  the  Las  Lajas  gage  bench 
No.  1,  108.737  feet.  The  Canal  Company's 
bench  on  the  boiler  at  San  Carlos  is  then  shown 
to  be  higher  than  No.  I  gage  bench,  if  we  use — 

No.  I  gage,  average  of  all  readings. .    .750  feet. 

"  II  gage,  average  of  all  readings. .    .622  feet. 

"  n  gage,  5  selected  days 579  feet. 

Canal  Company's  figures .728  feet. 

Levels  were  carried  across  the  lake  by  the 
Canal  Company,  and  connecting  their  levels 
with  No.  I  gage  bench  gives  the  last  figure. 

We  have  used  the  results  obtained  from  an  av- 
erage of  all  the  readings  on  gage  No.  11,  giving 
the  elevation  of  gage  bench  No.  I  as  108.694 
feet. 

The  readings  on  gage  No.  I  were  taken  when 
the  lake  was  discharging  the  maximum  amount 
of  water,  and  when  there  was  a  strong  east  wind 
blowing,  and  these  causes  may  have  made  the 
west  side  of  the  lake  li  inches  higher  than  the 
east,  as  the  gages  seemed  to  show. 

No.  II  gage  was  read  during  the  calmest 
period  of  the  year,  and  when  the  discharge  of 
the  lake  was  least.  The  result  we  use  is  the 
average  of  the  readings  for  77  days,  5  readings 
being  taken  each  day.  The  five  selected  days 
hardly  give  enough  readings  to  calculate  an  av- 
erage condition  of  the  lake  as  closely  as  we  ob- 
tain by  taking  all  the  readings  of  No.  11  gage. 


APPENDIX  IX.— REPORT  ON  PRECISE   LEVELS 


467 


o  Hms^ 


PRECISE  LEVEL  BENCH 

NQ  sa 

0  400  800 


\  \^rectse  Lewf  Bench  mzz 
^#o  Thmpormy  Bench  N^dZisd'spikc  in 

<fAS\AkanorOrk^  South  foot Jt'oMoPieqiwhc/,  of 
<rff-|!    A^.*.  Seibofree,3'mcf/ani,S5'N6(fW 

from  MW,  comer  of  house. 

Piermaneni' Bench  tfizz  is  3'S  Waf 
Temporcuy  Bench  Afszz. 


PRECISE  LEVEL  BENCH  No.  22. 

Mean  Elevation  above  Sea  Level. 

Temporary  Bench  No.  22 44.1266  m.  144.772  ft. 

Permanent  Bench  No.  22,  on  spike 42.9646  m.  140.960  ft. 

Permanent  Bench  No.  22,  on  stone 42.9428  m.  140.888  ft. 

Walker's  Bench  at  his  Sta.  361+17 35.2113  m.  115.522  ft. 

Instrument  No.  1.  Instrument  No.  8. 

Temporary  Bench  No.  22 44.1247  m.  144.766  ft.  44.1284  m.  144.778  ft 

Permanent  Bench  No.  22,  on  spike 42.9633  m.  140.955  ft  42.9659  m.  140.964  ft. 

Permanent  Bench  No.  22,  on  stone 42.9416  m.  140.884  ft  42.9439  m.  140.892  ft. 

Walker's  Bench  near  his  Station  361  +  17 35.2102  m.  115.519  ft  35.2123  m.  115.526  ft 

Bench  No.  22  is  7.6  miles  by  our  line  beyond  bench  The  bench  was  made  October  26th  and  elevations 

No.  21,  and  is  near  Nicanor  Ortega's  house  on  the  were  taken  by  instrument  No.  1  October  27th,  and 

road  from  Rivas  to  Carmen,  Just  north  of  the  Rio  by  instrument  No.  3  October  26th. 

Grande.  About  300  feet  south  of  our  bench  is  a  bench  made 

Temporary  bench  No.  22  is  a  6-inch  spike  in  the  by  Mr.  Walker  at  his  station  361  +  17.    This  bench 

south  root,  12  inches  above  the  ground,  of  a  seibo  is  a  spike  in  a  madrofie  tree  18  inches  in  diameter, 

tree  3  feet  in  diameter.  Between  benches  22  and  23  our  line  follows  approxi- 

Permanent  bench  No.  22  is  3  feet  southwest  of  the  mately  the  Canal  Company's  center  line  for  the  canal, 

temporary  bench,  and  is  a  spike  set  with  sulphur  in  Between  these  benches  backsights  were  read  first 

a  stone  buried  3  feet  below  the  surface.    Elevations  by  instrument  No.  1,  and  foresights  first  by  instru- 

were  taken  on  the  spike  and  on  the  center  of  a  IVi-  ment  No.  3. 

inch  square  cut  in  the  stone  3  inches  west  of  the  * 
spike. 


468 


NICARAGUA  CANAL  COMMISSION 


PRECISE  LEVEL  BENCH 

NQ  23 
0  400  800 


I 


\ 


Temporary  Bench  N9  23  is  el^spike  in 
south  rtxt,  /?'aPoi^fhe  ^ma,fff  ^aefninff 
free,  3  'm^iam.  ana  is  6  'n^taf       ^ 
V    Permanent  Bencn  N9  25. 

\\  JPtectse 


From  Mker^  5i».  IJi-f-lOfv 

Permanent  Bench  N^23  is 
Si  '580'W,  men  361 '  NSoy/ 


PRECISE  LEVEL  BENCH  No.  23. 

Mean  Elevation  above  Sea  lievel. 

Temporary  Bench  No.  23 15.3642  m.  50.407  ft. 

Permanent  Bench  No.  23,  on  spike *. .  14.4431  m.  47.385  ft. 

Permanent  Bench  No.  23,  on  stone 14.4317  m.  47.348  ft 

Walker's  Bench  20'' left  of  his  Sta.  758+CO 14.8104  m.  48.590  ft 

Instrument  No.  L  Instrument  No.  3. 

Temporary  Bench  No.  23 15.3665  m.  50.415  ft.  15.3618  m.  50.400  ft. 

Permanent  Bench  No.  23,  on  spike 14.4454  m.  47.393  ft  14.4406  m.  47.377  ft. 

Permanent  Bench  No.  23,  on  stone ; 14.4341  m.  47.356  ft  14.4293  m.  47.340  ft 

Walter's  Bench,  20  feet  left  of  his  Station  758  -f  60. . .  14.8133  m.  48.600  ft.  14.8075  m.  48.581  ft. 


Bench  No.  23  is  8.6  miles  by  our  line  beyond  bench 
No.  22.  It  is  on  the  first  hill  east  of  the  Pacific  on 
the  Canal  Company's  center  line  of  the  canal,  and  is 
near  the  proposed  La  Flor  dam,  and  about  400  feet 
right  of  Walker's  station  772. 

Temporary  bench  No.  23  is  a  6-inch  spike  in  the 
south  root,  12  inches  above  the  ground,  of  a  madrofie 
tree  3  feet  in  diameter. 

Permanent  bench  No.  23  is  6  feet  east  of  the  tem- 
porary bench,  and  is  a  spike  set  with  sulphur  in  a 
stone  buried  18  inches  below  the  surface.  Elevations 
were  taken  on  the  spike  and  on  the  center  of  a  1%- 


inch  square  cut  in  the  stone,  2  inches  south  of  the 
spike.  The  bench  was  made  October  31st  and  eleva- 
tions were  taken  November  Ist. 

About  1400  feet  northwest  of  bench  No.  23  is  a 
bench  made  by  Mr.  Walker  20  feet  left  of  his  station 
758  -f  60.  This  bench  is  a  nail  in  the  root  of  a 
nispero  tree. 

Our  line  from  bench  No.  23  to  bench  No.  24  follows 
the  north  bank  of  the  Rio  Grande.  Between  these 
benches  foresights  were  read  first  by  instrument  No. 
1,  and  backsights  first  by  instrument  No.  3. 


APPENDIX  IX.— REPORT  ON  PRECISE  LEVELS 


469 


f¥9ci5e  le¥9/  3mcA  A/S24 
>^  \     .  Temponary  Bmc/7  N9Z4-f5  d' spike  in  Mansano  free 

z'inilkmi.  Spikt  is  in  west  root  /eye/  wH/i  ihe  surface. 

Tfiefreeis  f^from  the  shore  ina/if//egu//ef.  /fis 

martcec/on  the  nor/^sr^e  withafrarrotyanctCC.C.6. 
tS$S rnoE6A6E^.  N.P Ok;/ ii/eaibi^ cu/tm 

on  ' 


wesZ-L 


^  /^rmanenf  Bench  is  9  'soa/h  of  lemportfry  Bench 


BR/TO   HARBOR 


PAC/FIO 


OCEAN 


Alert  Tide  6age  Bench  on poin/- of  rocks  Juth'ngotft info 
Ihe  sea.  /fis  marf^ed  bf Jt^^^  a/fin  ihe  rodr, 

PRECISE   LEVEL- BENCH 
N$  24. 

P 400  900, 


SCALE. 


PRECISE  LEVEL  BENCH  No.  24. 

Mean  Elevation  above  Sea  Level. 

Temporary  Bench  No.  24 2.8380  m.  9.311  ft 

Permanent  Bench  No.  24,  on  spike 3.0956  m.  10.156  ft. 

Permanent  Bench  No.  24,  on  stone 3.0785  m.  10.100  ft. 

''  Alert"  Bench 3.6366  m.  11.931  ft. 

Instrument  No.  1.  Instrument  No.  8. 

Temporary  Bench  No.  24 2.8386  m.  9.313  ft.  2.8374  m.  9.309  ft. 

Permanent  Bench  No.  24,  on  spike 3.0967  m.  10.156  ft.  3.0955  m.  10.156  ft. 

Permanent  Bench  No.  24,  on  stone 3.0787  m.  10.101  ft.  3.0782  m.  10.099  ft. 

"  Alert "  Bench  3.6357  m.  11.928  ft.  3.6374  m.  11.934  ft 


Bench  No.  24  is  at  the  mouth  of  the  Rio  Grande, 
on  the  west  bank. 

Temporary  bench  No.  24  is  a  6-inch  spike  in  a 
mansano  tree  2  feet  in  diameter.  The  spike  is  in  the 
west  root,  level  with  the  surface.  The  tree  is  15  feet 
from  the  edge  of  the  water  in  a  little  gully.  It  is 
marked  on  the  north  side  with  an  arrow  and  ''  C.  C. 
C.  E.  April  1888.  Tide  gage  B.  M.  N.  P."  There  is 
an  old  illegible  cutting  on  the  west  side. 

Permanent  bench  No.  24  is  9  feet  south  of  the  tem- 
porary bench.    It  is  a  spike  set  with  sulphur  in  a 


stone  buried  1  foot  below  the  surface.  Elevations 
were  taken  on  the  spike  and  on  a  1^-inch  square 
cut  in  the  stone  2  inches  north  of  the  spike.  The 
bench  was  made  November  1st  and  elevations  were 
taken  November  2nd,  1898. 

The  bench  to  which  the  Brito  tide  gagings  were 
referred  is  about  1500  feet  south  of  our  bench  No.  24, 
and  is  on  a  point  of  rocks  Jutting  out  into  the  sea. 
It  is  marked  by  a  triangle  and  cross  lines,  and  "Alert, 
1898." 


470 


NICARAGUA  CANAL  COMMISSION 


The  tide  gagings  at  Brito  were  made  by  the 
officers  of  the  U.  S.  S.  Alert.  Two  gages  were 
used,  one  called  the  outer  gage,  the  other  the 
inner.  Both  gages  were  connected  by  the  Alert 
people  with  their  bench  at  Brito,  and  the  mean 
daily  sea  level,  for  each  day  the  gages  were  read, 
has  been  found  by  plotting  the  readings  just  as 
was  done  with  the  Greytown  tide  gage  readings. 
The  outer  gage  was  often  disturbed  by  the  vio- 
lence of  the  waves,  and  had  to  be  reconnected 
with  the  bench,  while  the  inner  gage  remained 
at  one  height  during  all  the  readings.  These 
daily  mean  sea  level  values  were  then  plotted  as 
urdinates,  the  line  joining  their  extremities 
showing  the  variation  of  mean  daily  sea  level. 

For  the  outer  gage  we  have  29  mean  daily 
sea  level  values  between  February  16th  and 
March  21st,  1898,  and  the  average  of  these 
values  shows  mean  sea  level  to  be  12.856  feet 
below  the  Alert  bench  mark. 

For  the  inner  gage  we  have  49  mean  daily  sea 
level  values  between  February  19th  and  April 
8th,  and  the  average  of  these  values  shows  mean 
sea  level  to  be  12.886  feet  below  the  Alert  bench 
mark. 

Mean  sea  level  values  for  the  inner  gage  dur- 
ing a  selected  period  of  29  days  show  mean  sea 
level  to  be  12.901  feet  below  the  Alert  bench 
mark. 

Taking  12.886  feet  the  average  of  all  the 
readings  on  the  inner  gage  as  probably  nearest 
right,  this  shows  mean  Pacific  sea  level  at  the 
time  these  readings  were  taken  to  be  .995  foot 
below  mean  Atlantic  sea  level.  The  Canal 
Company's  Pacific  mean  sea  level  is  .328  foot 
below  mean  Atlantic  sea  level. 


The  Alert  Brito  tide  gage  readings  did  not 
extend  over  a  long  enough  period  to  determine 
accurately  the  mean  level  of  the  Pacific  ocean, 
as  the  monthly  variation  of  the  mean  height  of 
the  ocean  in  this  locality  is  considerable. 

The  tide  tables  published  by  the  Coast  Sur- 
vey show  that  at  Panama,  during  the  period 
when  these  readings  were  taken,  the  sea  was  one 
foot  below  the  normal,  and  if  this  was  also  the 
case  at  Brito,  our  levels  show  mean  sea  level  for 
the  two  oceans  to  be  the  same. 

The  highest  high  tide  observed  by  the  Alert 
people  was  4.9  feet  above  the  mean  level  of  the 
Pacific  ocean  as  given  by  the  Alert  gages,  or 
3.9  feet  above  mean  Atlantic  sea  level. 

The  lowest  low  tide  was  4.4  feet  below  the 
mean  level  of  the  Pacific  ocean  as  given  by  the 
Alert  gages,  or  5.4  feet  below  mean  Atlantic 
sea  level,  the  extreme  range  of  the  tide  being 
9.3  feet. 

The  mean  of  the  daily  highest  water  eleva- 
tions was  3.42  feet  above  the  mean  level  of 
the  Pacific  ocean  as  given  by  the  Alert  gages, 
or  2.46  feet  above  mean  Atlantic  sea  level. 

The  mean  of  the  daily  lowest  water  elevations 
was  3.38  feet  below  the  mean  level  of  the  Pa- 
cific ocean  as  given  by  the  Alert  gages,  or  4.34 
feet  below  mean  Atlantic  sea  level. 

The  mean  of  all  high  tides  was  3.15  feet  above 
the  mean  level  of  the  Pacific  ocean  as  given  by 
the  Alert  gages,  or  2.19  feet  above  mean  At- 
lantic sea  level. 

The  mean  of  all  low  tides  was  3.13  feet  below 
the  mean  level  of  the  Pacific  ocean  as  given  by 
the  Alert  gages,  or  4.09  feet  below  mean  At- 
lantic sea  level. 


APPENDIX   IX.—REPORT  ON   PRECISE   LEVELS 


471 


COMPARISON  OF  PRECISE  LEVEL  ELEVATIONS  WITH  ELEVATIONS  GIVEN  BY  H.  H.  TRUNDLE 

AND  BY  THE  CANAL  COMPANY  BETWEEN  GREYTOWN  AND  OCHOA. 

All  the  elevations  are  given  in  feet. 


Canal  Co.'s  bench  in  machine  shop 

near  Grey  town 

Track  spike  on  north  side  of  north 

rail  at  Sta.  85 

Track  spike  on  north  side  of  north 

rail  at  Sta.  112 

Track  spike  on  north  side  of  north 

rail  at  Sta.  174 

Track  Spike  at  Sta.  216 

Track  spike  at  Sta.  224  (P.  L.  bench 

No.  4  is  near  Sta.  282) 

Track  spike  on  south  side  of  south 

rail  at  Sta.  251+36 

Nail  in  root  of  stump  40  ft.  L.  of 

Sta.  406  +  30 

Track   spike  north  side  of  north 

rail  at  Sta.  500  +  03 

Precise  level  bench  No.  4  on  glass 
Nail  in  root  of  old  18^'  stump  16.5^ 

L.  of  Sta.  587  +  12.5 

Precise  level  bench  No.  5  on  glass 
Nail  in  root  of  18'^  tree  400^  L.  of 

Sta.  723  +  60 

Canal    Co.'s    copper  f  Trundle's 

bolt  in  root  of  tree   |       elev 

100^  right  of   Sta.  . 


KlevatloDB  from 

Trundle's  field 

notes,  corrected 

to  agree  with 

precise  level 

field  elevations. 


Elevations  from 

Trundle's 

field  notes, 

with  corrections 

taken  out,  and 

Canal  Co.'s 

elevations. 


Canal  Co.'s 
elev 


806  on  north  bank 
of  Rio  Deseado 

Precise  level  bench  No.  6  on  glass 

Nail  In  root  of  30^'  almendro  tree 
65'  L.  of  Sta.  957  +  20  on  east 
bank  of  Cailo  Limpio  near  old 
Camp  Alice    

Canal    Co.'s    copper   pTrundle's 

bolt   in   stump  of         elev 

redwood  tree  14'^  J  Canal  Co.'s 
dia.  near  Camp  ]  Istelev.. 
Carmen  at  Sta.  Canal  Co.'s 
1047  +  50  [    2d  elev.. 

Precise  level  bench  No.  7  on  glass 

Spike  in  root  of  60'^  tree  at  Sta. 
1117  +  80  on  east  bank  of  Rio 
Chanchos 

Nail  in  30'^  tree  on  east  bank  of 
Rio  San  Francisco  at  Hydrograph- 
ic  Station  near  Sta.  1250 

Canal  Co.'s  bench  45  ft.  right  of 
Sta.  1352,  described  by  Canal  Co.'s 
notes  as  at  Sta.  1352.  Blazed 
tree  15^'  dia.  No  nail  in  bench. 
Bench  somewhat  overgrown  with 
bark.  Tlie  connection  with  the 
precise  level  line  was  made  by 
Trundle's  party  from  the  San 
Francisco  bench.  Canal  Co.'s 
elevation 

Nail  in  root  of  large  almendro  tree 
on  telegraph  line  about  opposite 
Sta.  1546  +  75 

Nail  in  root  leaning  tree  north  bank 
of  San  Juan  river,  opposite  Hy- 
drographic  Camp,  and  15'  L.  of 
Sta.  1678  +  20 


4.538 

8.422 

7.243 

9.449 
12.611 

14.426 

11.804 

16.370 

20.978 
24.195 

26.197 
93.992 

41.089 

58.316 

122.200 


•246.627 
99.2$)6 

134.513 
52.129 
51.107 


144.807 


71.280 


4.538 

8 .  422 

7.243 

9.449 
12.611 

14.426 

11.304 

15.870 

20.978 
24.195 

26.197 
93.772 

40.950 

68.177 


58.420 
121.727 


246.154 

98.715 

99.727 

98.727 
133.932 

51.630 

50.703 


76.063 


144.488 


Elevations 
reduced  to  mean 

sea  level  by 

the  addition  of 

.520  ft. 


70.961 


5.058 

8.942 

7.763 

9.969 
13.131 

14.946 

11.8*24 

15 . 890 

21.498 
24.715 

26.717 
94.292 

41.470 

58.697 


58.940 
122.247 


246 . 674 

99.235 

100.247 

99.247 
134.452 

52.150 

51.223 


76.583 


145.008 


71.481 


Dlfl!erenee. 


.000 
+  .026 

—  .142 

—  .196 

—  .193 

—  .262 
— .  255 

—  .310 

—  .387 

—  .175 

—  .185 

—  .065 

—  .255 

—  .453 


—  .210 

—  .486 


—  .550 

—  .419 
+  .593 

—  .407 

—  .424 

—  .369 

—  .345 


—  .025 


—  .232 


—  .263 


Precise 

level 

elevations. 


5.058 

8.916 

7.905 

10.165 
13.324 

15.208 

12.079 

16.200 

21.885 
24 . 890 

26.902 
94.357 

41.725 

59.150 


59.150 
122.733 


247.224 

99.654 

99.654 

99.654 
134.876 


52.519 


51.568 


76.608 


145.240 


71 . 744 


Precise  level 

instrument 

No.  1. 


5.044 

8.941 

7.931 

10.210 
13.374 

15.258 

12.125 

16.224 

21.903 
24.913 

26.910 
94.366 

41.716 

59.141 


59.141 
122.716 


247.281 

99.686 

99.686 

99.686 
134.904 


52 . 522 


51.573 


145.263 


Precise  level 

Instrument 

No.«. 


6  .i)72 

8.891 

7.878 

10.120 
13.274 

12.038 


21.867 
24.866 

26 . 895 
94.349 

41.784 

59.158 


59.158 
122.750 


247.216 


99.6*21 

99.621 

99.621 
134.848 


52.516 


51.563 


71 . 747    71 . 740 


145.218 


472 


NICARAGUA   CANAL  COMMISSION 


COMPARISON  OF  PRECISE  LEVEL  ELEVATIONS  WITH   ELEVATIONS   GIVEN   BY   F.    L.   STUART 

BETWEEN  OCHOA  AND  SAN  CARLOS. 
Stuart's  elevations  are  taken  from  the  Canal  Company's  elevation  of  the  bench  at  San  Carlos,  which 

elevation  is  derived  from  their  Pacific  levels. 
All  the  elevations  are  given  in  feet. 


Stuart's 
No.  1 
Line. 


Spike  in  north  root  of  cotton  wood  tree  5  ft.  in 
dia.  This  tree  is  15  ft.  from  the  north  bank  of 
the  Rio  San  Juan,  near  Ochoa  telegraph  station . 
Nail  in  root  of  leaning  tree  on  north  bank  of  San 
Juan  river,  opposite  Uydrographic  Camp  and 
15  ft.  L.  of  Sta.  1078  +  12  of  trundle's  line,  and 
last  bench  on  that  line.  Stuart's  difference  at 
this  point,  which  is  just  above  Ochoa,  is  inter- 
polated between  +.069  and  +.073  proportion- 
ately to  the  distance 

Stuart's  Sta.  604 

592 

590 

588 

584 

578 

576 


68.41 


ii 


ti 


t( 


(i 


li 


it 


vi 


it 


li 


li 
ii 
il 
.1 
ii 
ii 
li 
ii 


ll 


'»     562 


'»  .554 

'*  526 

'»  276 

'*  242 

"  238 


62.20 
59.47 
61.H2 
60.78 
61.93 
62.95 
58.97 
61.45 
64.37 
64.04 
71.46 
85.20 
84.27 


"     210 

Stuart's    Bench. — Nail  in  northeast  root  of  jobo 

tree,  3  ft.  in  diameter,   on   west  bank  of  Kio 

Savalos 

Stuart's  Bench,  75^  west  of  his  Station,  No.  14,  on 

north  root  of  chilati  tree,  2  ft.  in  dia 

Canal  Co.'s  Bench. — Cross  cut  in  north  end  of  old 

steamboat  boiler  in  lake  at  San  Carlos 


Stuart's 
No.  2 
Line. 


68.41 


62.88 
59.52 
61.38 
60.86 
62.03 

•   •   «   •    • 

59.10 
61.50 
64.29 
64.01 
71.37 
85.17 
84.14 


Stuart's 

mean 

elevation. 


Difference 


68.410 


71.813 
62.290 
59.495 
61.350 
60.820 
61.980 
62.950 
59.035 
61.475 
64.380 
64.025 
71.415 
85.185 
84.205 
92.760 


103.590 
107.980 
109.750 


Precise 

level 

elevations. 


'    Precise 

I      level 
Instrum't 
No.l. 


+  .069   68.341 


+  .070 
+  .073 
+  .013 
+  .031 
+  .051 
+  .041 
+  .048 
+  .105 
+  .026 
+  .117 
+  .081 
—  .048 
+  .042 
+  .043 
+  .084 


—  .118 
+  .313 
+  .484 


71.743 
62.217 
.59.482 
61.819 
60.769 
61.939 
62.907 
58.980 
61.349 
64.213 
63.944 
71.458 
85.143 
84.162 
92.676 


103.708 
107.667 
109.816 


Precise 

level 

Instrum't 

No.  8. 


68.842 


71.747 
62.211 
59.462 
61.297 
60.741 
61.921 
62.890 
58.920 
61.357 
64.223 
63.954 
71.453 
85.137 
84.149 
92.661 


103.684 
107.685 


109.316 


68.841 


71 . 740 
62.224 
.59.502 
61.843 
60.797 
61.957 
62.924 
58.940 
61.340 
64.202 
63.985 
71.462 
85.149 
84.175 
92.692 


108.721 


107.681 


109.815 


COMPARISON  OF  PRECISE  LEVEL  ELEVATIONS  WITH  ELEVATIONS  GIVEN  BY  J.  W.  G.  WALKER 
TAKEN  FROM  THE  CANAL  COMPANY'S   BENCHES  WEST  OF  LAKE  NICARAGUA. 

All  the  elevations  are  given  in  feet. 


Spike  in  root  of  roble   tree,   126^ 

S.  E.  of  Sta.  0 

Spike  in    root  of  roble   tree,   126^ 

8.  E.  of  Sta.  0 

Spike  in   root  of  madroiie  tree  at 

Sta.  361  +  17 

Spike  in  root  of  raadroile  tree  at 

Sta.  361  +  17 

Spike  in  nispero  tree  20^  L.  of  Sta. 

758  +  60   

Alert  tide-gage  bench 


Elevations 

given  by 

J.  W.  u.  Walker. 

taken  from 

CanalCoropauy's 

Bench 

near  bta.  0. 


112.540 


Elevations 

given  by 

J.  W.O.Walker 

taken  from 

Canal  Co.'9 

Bench  near  Bta. 

611  +  20. 


Subtract  .828  ft. 

to  reduce  to 

mean  Atlantic 

sea  level. 


Difference. 


115.815 


112.326 

115.601 
48.932 
12.259 


I 


112.212      .000 

111.1H)8    —.214 

.035 

.249 


115.487 
115.273 


48.604 
11.981 


+  .014 
—  .000 


Precise 

level 

elevations. 


112.212 
112.212 


115.522 


115.522 


48.590 


11.931 


Precipe 

level 

Inntrument 

No.l. 


112.196 
112.196 


115.519 


115.519 


48.600 
11.928 


Precise 

level 

instrument 

No.S. 


112.227 
112.237 


115.536 


115.526 


48.581 


11.984 


APPENDIX  IX.— REPORT  ON  PRECISE  LEVELS 


473 


The  preceding  tables  give  a  third  line  of 
levels  from  Greytown  to  Brito.  These  tables 
comparing  the  third  line  with  our  line  are  given 
to  show  that  there  is  no  possibility  of  any  large 
error  in  our  work. 

The  first  table  gives  the  levels  from  Greytown 
to  a  bench  just  above  Ochoa.  These  are  the 
levels  of  Tnmdle's  party  and  were  rim  by  Dion 
Martinez  with  an  ordinary  Y  level.  There  are 
also  given  on  this  part  of  the  line,  three  checks 
with  old  Canal  Company  benches,  all  that  we 
were  able  to  find  on  this  line. 

Trundle's  levels  and  our  field  levels  are  based 
on  the  Canal  Company's  elevation  of  the 
bench  in  the  machine  shop  near  Greytown.  The 
first  column  gives  Trundle's  levels  as  recorded 
in  his  field  books.  These  levels  were  kept  with 
our  field  levels  by  correcting  them  to  agree 
with  our  levels  at  eight  places.  In  order  to 
make  an  independent  line,  these  corrections 
have  been  taken  out,  and  the  second  column 
gives  elevations  from  Tnmdle's  uncorrected 
work.  In  the  third  column,  these  elevations 
have  been  reduced  to  mean  sea  level  bv  the  ad- 
dition  of  .52  ft. 

The  fourth  column  gives  the  difference  be- 
tween Trundle's  levels  and  ours.  The  maxi- 
mum difference  is  at  the  highest  point  at  which 
we  compared  elevations  and  is  .55  ft.  Tlio  final 
difference  is  .2G3  ft. 

In  the  half  mile  between  station  85  and  sta- 
tion 112  there  is  a  change  in  the  difference  of 
the  elevations  of  .168  ft. 

We  ran  this  part  of  tlie  line  over  to  make 
sure  the  mistake  was  not  in  our  work,  and  the 
result  differed  from  our  first  running  by  .01  ft. 
If  in  this  short  piece  of  line  which  we  have  re- 
TXiUy  we  substitute  our  running  for  Trundle's, 
the  maximum  difference  in  our  lines  is  .382  ft. 
and  the  final  difference  is  .095  ft. 


After  leaving  Greytown  the  first  Canal  Com- 
pany bench  we  found  was  near  our  bench  No.  6, 
at  Camp  Warner  Miller,  where  we  differ  from 
the  Canal  Company's  deviation  by  .21  ft 

The  next  Canal  Company  bench  we  found 
was  near  our  bench  Xo.  7.  This  bench  is  not 
on  the  Canal  Company's  original  line,  the  line 
over  which  they  carried  their  check  levels,  but 
is  on  a  later  line  run  from  Chanchos  river  to 
Camp  Saltos,  the  first  camp  east  of  the  divide. 
This  line  did  not  check  with  the  original  check 
leveled  line,  hence  the  two  sets  of  elevations. 
Our  elevation  comes  in  between  their  two  ele- 
vations, differing  .6  ft.  from  one  and  .4  ft.  from 
the  other. 

The  next  Canal  Company  bench  we  found 
was  west  of  the  San  Francisco  river,  where  we 
again  meet  their  through  line  of  levels.  Our 
elevation  for  this  bench  differs  from  theirs  by 
.025  ft.  This  was  the  last  Canal  Company 
bench  we  were  able  to  find  east  of  the  lake. 

At  Ochoa  we  passed  Stuart's  party  working 
down  the  river,  and  were  given  their  elevations 
for  all  their  stations.  These  levels  were  run  by 
S.  S.  Evans  with  an  ordinary  transit  in  connec- 
tion with  the  survey  work  of  the  river.  They 
started  with  the  Canal  Company's  elevation  for 
their  bench  on  the  boiler  at  San  Carlos  which 
elevation  is  derived  from  their  levels  west  of 
the  lake,  so  that  Stuart's  and  Walker's  levels 
form  a  continuous  line. 

Stuart  did  not  tie  to  Trundle's  line,  but  tied 
to  our  line  above  and  below  Trundle's  last 
bench,  and  by  interpolating  a  difference  for  this 
bench,  we  obtain  the  result  shown,  in  the  table. 

From  Castillo,  down  the  river,  Stuart  carried 
a  duplicate  line  of  levels,  using  the  turning 
points  on  the  north  side  of  the  river  for  one  line, 
and  those  on  the  south  side  for  the  other,  and 
on  this  part  of  the  line  we  check  with  him  very 


474 


NICARAGUA   CANAL  COMMISSION 


closely,  our  maximum  difference  being  one- 
tenth  of  a  foot.  From  Castillo  to  the  lake, 
there  is  a  single  line,  and  as  the  river  in  this  part 
of  the  line  runs  through  swamp  and  the  transit 
head  was  set  up  on  sawed  off  trees  standing  in 
the  water,  we  could  not  expect  to  check  as 
closely.  Our  levels  at  San  Carlos  differ  from 
Stuart's  by  .434  ft.  which  is  .361  ft.  greater  than 
the  difference  at  Ochoa.  We  differ  from  the 
Canal  Company  in  crossing  the  lake  by  .106  ft. 

West  of  the  lake  we  have  Walker^s  levels,  run 
with  an  ordinary  Y  level,  H.  C.  Hurd,  levelman. 
These  levels  start  with  a  Canal  Company's  bench 
on  the  lake  and  change  .214  ft.  to  agree  with  the 
Canal  Company  benches  nearer  the  Pacific. 
The  maximum  difference  between  our  levels  and 
Walker's  connection  with  the  nearest  Canal 
Company  bench  is  .035  ft  and  at  the  Alert  tide 
gage  bench  we  agree  exactly. 

Trundle's  elevation  for  his  last  bench  is 
71.481  ft. 

Stuart's  elevation  for  this  bench  is  71.813 
feet. 

To  make  Stuart's  line  and  Walker's  line  con- 
tinuous with  Trundle's,  we  must  deduct  from 
their  elevations  the  difference  between  71.813  ft. 
and  71.481  ft.  or  .332  ft.  which  gives  for  the  ele- 
vation of  the  Alert  bench  at  Brito,  11.927  ft.  as 
against  11.931  ft.,  our  mean  elevation. 

The  unit  measure  used  on  this  combination 
line  was  1  ft.  and  on  our  line,  1  meter,  so  there 
is  no  possibility  of  a  unit  mistake  on  one  of  the 
lines  being  balanced  by  a  similar  mistake  in  the 
other. 

The  greater  part  of  Trundle's  line  was  run 
after  our  line.  Stuart's  and  Walker's  lines  were 
niu  before  our  line.     Trundle's  and  Walker's 


lines  were  run  in  the  same  direction  as  ours. 
Stuart's  in  the  opposite  direction. 

Our  line  from  Greytown  to  Brito  was  carried 
over  136  miles  of  land  and  70  miles  of  water,  o^ 
206  miles  in  all. 

By  assuming  none  of  the  errors  in  our  two 
lines  to  be  cumulative,  or  all  to  be  compen- 
sating, and  to  vary  as  the  square  root  of  the  dis- 
tance run,  we  have  found  between  each  two 
benches  the  probable  error  introduced  in  our 
mean  elevation,  and  the  rate  per  mile  of  this 
error,  and  from  this,  the  average  rate  per  mile 
for  the  whole  line. 

Determined  in  this  way,  .00131  m.  (.0043 
ft.)  was  the  average  rate  per  mile  for  the  prob- 
able error  introduced  in  our  mean  elevations, 
and  multiplying  this  rate  per  mile,  by  the  square 
root  of  136,  the  number  of  miles  run  gave 
.0153  m.  (.0502  ft.)  as  the  probable  error  in  our 
final  elevation  introduced  in  carrying  the  levels 
over  the  land  part  of  the  line.  Determined  in 
this  same  way,  the  average  difference  between 
the  two  lines  per  mile  run,  was  .00393  m. 
(.0129  ft.). 

The  average  daily  difference  between  the  two 
lines  was  .0042  m.  (.0138  ft.)  and  the  average 
daily  probable  error  in  our  mean  elevation  was 
.0014  m.  (.0046  ft).  Multiplying  this  average 
daily  error  by  the  square  root  of  174  (the  num- 
ber of  days  we  ran),  gives  .0185  m.  (.0607  ft.) 
as  the  probable  error  in  our  final  elevation  intro- 
duced in  carrying  the  levels  over  the  land  part 
of  the  line,  considering  none  of  the  errors  to  be 
cumulative. 

Very  respectfully  yours, 

Stephen  Harris, 
Assistant  Engineer. 


APPENDIX  X 


REPORT  OF  ANDREW  ONDERDONK 

Assistant  Engineer 


CONTENTS 


PA(}K 


Greytown  Harbor  Survey 479 

Personnel   479 

Measuring  the  Base  line 479 

Lower  San  Juan  River  Survey 479 

Taura  River  Survey 479 

Draughting  Room  at  Greytown : 479 

Volcanic  Sand  along  the  Seacoast 480 

Coast  Line  Examined t . . .  480 

Simon  and  Agua  Dulce  Lagoons 480 

Parasmina  River   481 

Greytown 481 

North  of  the  Indian  River 482 


APPENDIX  X 


Washington,  D.  C,  April  10,  1899. 
Mb.  E.  S.  Wheblbb, 

Chief  Engineer,   Nicaragua  Canal  Commis- 
sion, Washington,  D.  C. 

Sir: — I  have  the  honor  to  submit  herewith  a 
report  of  my  work  under  the  Nicaragua  Canal 
Commission,  while  in  Nicaragua,  C.  A. 

After  having  arrived  in  that  country  upon 
the  18th  of  December  1897,  I  received  a  letter 
of  instructions  dated  December  21,  1897,  stat- 
ing that  I  was  to  take  charge  of  a  topographic 
party  for  the  purpose  of  making  an  outline  sur- 
vey of  Greytown  harbor,  and  at  the  same  time 
naming  the  men  that  were  to  constitute  the 
officers  of  that  party.  These  names  are  as  fol- 
lows with  the  rank,  to  which  I  assigned  them,  ap- 
pended: Wm.  G.  Fitzgerald,  transitman;  John 
Carmichael,  levelman;  Wm.  D.  Thomas,  rod- 
man  ;  Louis  E.  Lannan,  chainman  and  Adolf o  V. 
Montes,  backflagman. 

Actual  work  was  commenced  by  taking  the 
toiX)graphy  in  the  vicinity  of  La  Fe.  All  lines 
were  run  by  transit  and  measurements  taken  with 
a  100-ft.  steel  tape  or  by  triangulation.  One  of 
the  first  things  done  was  to  establish  a  base  line 
two  miles  in  length  for  the  use  of  the  Newport 
hydrographic  party.  This  base  line  was  laid 
off  upon  practically  level  ground  and  measured 
twice  with  a  steel  tape,  the  first  measurement 
being  made  at  a  temperature  of  75^  F.  and  the 
second  at  108°  F.     After  making  the  correction 


for  temperature  the  difference  in  the  two  meas- 
urements was  about  2  inches  in  the  10,500  feet. 

The  survey  was  then  continued,  accurately  de- 
termining the  shore  lines  of  the  sea,  lagoons  and 
islands  between  the  mouth  of  Indian  river  and 
one  mile  south  of  Harbor  Head  lagoon.  This 
work  was  completed  January  24,  1898,  when  in 
accordance  with  your  instructions  I  continued 
my  survey  up  the  lower  San  Juan  river  by 
means  of  stadia  measurements  of  courses  run- 
ning generally  diagonally  from  one  side  of  the 
river  to  the  other,  and  varying  from  400  to 
1400  feet  in  length.  The  levels  were  based  on 
the  Maritime  Canal  Company^s  bench  mark  in 
the  machine  shop  near  La  Fe.  They  were  car- 
ried immediately  after  the  transit  party,  using 
the  transit  hubs  for  turning  points.  Soundings 
of  the  river  weje  taken,  as  a  rule,  opposite  each 
transit  hub  and  at  right  angles  to  the  river.  This 
river  work  extended  for  about  12  miles  up  the 
lower  San  Juan  river  and  included  the  Taura 
river,  which  is  4  miles  long. 

On  March  12  in  accordance  with  your  further 
instructions,  I  broke  up  camp  and  reported  at 
headquarters  to  take  charge  of  the  draughting 
room.  This  position  I  retained  until  leaving 
Nicaragua  on  16th  of  September.  During 
which  time  my  assistants  were  Ralph  Begien 
from  March  24  to  July  15,  E.  C.  Wheeler  from 
April  1,  to  May  1,  Horace  F.  Collins  from  May 
5  to  Sept.  16. 

Besides  this  work,  as  there  was  a  lack  of  any 


480 


NICARAGUA   CANAL  COMMISSION 


definite  information  regarding  the  distance  the 
volcanic  sand  extends  along  the  seacoast,  agree- 
able to  your  instructions  I  made  a  reconnois- 
sance  of  the  coast  in  May  and  June  covering  a 
distance  of  50  miles  southward  and  35  miles 
northward  from  Greytown,  finding  this  sand  at 
both  extremities  of  mv  reconnoissance.  Mv  re- 
port  to  you  upon  this  subject  made  in  June, 
1898,  is  herewith  submitted. 

Very  Respectfully, 

Andrew  Onderdoxk, 
Assistant  Engineer. 

Volcanic  Sand  along  the  Seacoast. 

In  accordance  with  vour  verbal  instructions  of 
May  18  to  make  such  investigations  along  the 
coast,  both  northward  and  southward  from  the 
mouth  of  the  Colorado  river,  as  would,  at  least, 
tend  towards  the  determination  of  the  amount, 
extent  and  direction  of  the  drift  of  the  volcanic 
sand  delivered  to  the  sea  through  the  channels 
of  the  San  Carlos,  San  Juan  and  Colorado  rivers, 
I  left  Grevtown  on  May  20  in  a  canoe  with  two 
paddlers  and  ten  days'  provisions,  for  my  south- 
ern trip,  taking  the  following  route:  Up  the 
lower  San  Juan  river  to  Pereira  creek,  down 
that  creek  and  through  a  lagoon  bearing  the 
same  name,  to  the  Colorado  river;  thence  to  the 
mouth  of  that  river  at  Colorado  bar;  thence  up 
the  river  to  Simon  lagoon;  through  that  lagoon 
to  the  seacoast;  thence  by  foot  along  the  beach 
to  Turtle  Bogue;  thence  by  canoe  through  Islote 
lagoon  and  Petrel  creek  to  Parasmina;  thence 
up  the  Eeventazon  river  about  two  miles.  When 
I  had  reached  this  point  I  concluded  that  it 
would  be  unnecessary  to  proceed  further  as  I  had 
found  the  conditions  so  different  from  what  I 
had  anticipated  when  I  made  my  meager  ar- 
rangements for  the  reconnoissance.  I  therefore 
turned    back    taking    the    same    route    home- 


ward as  far  as  Colorado  bar,  thence  I  took  the  sea 
to  Harbor  Head;  thence  by  the  way  of  lower 
San  Juan  river,  Cafio  de  Animas  and  Greytown 
lagoon,  arriving  at  Greytown  in  the  afternoon  of 
Saturday,  May  28.  On  June  the  1st  I  started 
northward  walking  to  the  mouth  of  Indian  river, 
whore  I  hired  a  canoe.  In  this  canoe  I  went  up 
the  Indian  river  (stopping  over  night  upon  the 
beach  about  two  miles  above  the  mouth  of  the 
river)  to  Indian  creek,  through  this  creek  to 
Haulover  lagoon  and  Spanish  creek,  from  this 
point  I  walked  along  the  l>each  to  Point  of 
Rocks,  at  w-hich  point  I  turned  back  taking  the 
same  route  homeward  as  in  going,  arriving  at 
headquarters  in  the  afternoon  of  Sunday,  June 
the  5th. 

Accomjianving  this  report  is  an  enlargement 
of  a  portion  of  Luis  Friederichsen's  map  of  Costa 
Rica,  corrected  from  maps  of  the  Nicaragua 
Canal  Commission,  1898,  the  navigation  chart 
of  188G  and  my  own  notes. 

ilv  observations  and  conclusions  are  as  fol- 
lows.  In  the  first  place,  both  Simon  and  Agua 
Uulce  lagoons  show^  evidences  that  they  had 
been  former  channels  of  the  Colorado  river,  giv- 
ing a  range  of  about  twelve  miles  within  which 
the  mouth  of  that  river  has  shifted.  And  then 
at  the  mouth  of  Agua  Dulce  lagoon  and  again 
at  the  mouth  of  Simon  lagoon  the  banks  of  the 
river  are  composed  of  hard,  compact  strata  of 
sand.  How  much  further  up  the  river  this  sand 
extends  I  cannot  say  but  in  all  probability,  for 
several  miles,  and  for  an  even  greater  dis- 
tance on  either  side  of  the  river,  making  it 
possible  that  the  river  mouth  at  one  time  w^as 
anywhere  between  the  vicinity  of  Greytown  and 
that  of  Turtle  Bogue,  thus  rendering  it  difficult 
to  determine  which  way  the  sand  has  drifted 
since  it  was  delivered  to  the  sea  or  even  what 
river   made   the   deliverv.     I   found   at   Islote 


APPENDIX  X.— REPORT   OF  A.   ONDERDONK.   ASSISTANT   ENGINEER 


481 


Point  the  same  stratum  of  compact  sand  that  is 
exposed  in  the  banks  of  the  Colorado  river.  I 
also  found  the  same  character  of  sand  in  the 
bottom  of  Petrel  creek,  in  the  bottom  of  Cali- 
fornia river  and  in  shoals  on  the  convex  side  of 
the  bends  in  the  Reventazon  river.  Besides 
this  I  was  told  that  this  same  sand  was  to  be 
found  as  far  up  the  Reventazon  river  as  its  junc- 
tion with  the  Parasmina  river  and  that  the  bot- 
tom of  that  river  was  composed  of  round  boul- 
ders varying  in  size  from  that  of  a  hen's  egg  on 
up  to  a  much  greater  size.  Upon  examining 
some  boulders  found  at  the  mouth  of  the  Reven- 
tazon river  answering  to  the  description  given 
of  those  in  Parasmina  river,  they  appeared  to 
be  composed  of  the  same  material  as  that  of  the 
volcanic  sand  in  question,  which  seems  to  indi- 
cate that  other  rivers  having  their  source  in  the 
same  volcanic  region  as  the  San  Carlos,  have 

been  and  still  are  bringing  sand  to  the  coast, 
besides  the  Colorado. 

As  far  south  as  Parasmina  there  is  no  appar- 
ent diminution  of  sand  from  that  between  Har- 
bor Head  and  Colorado  bar,  but  it  is  much 
lighter  in  color  and  finer  in  grain,  bearing  a 
closer  resemblance  to  that  found  north  of  In- 
dian river,  but  it  is  not  so  light  and  fine  as  that 
found  north  of  Spanish  creek.  This  peculiarity 
might  indicate  that  it  had  drifted  for  some 
distance  and  had  lost  its  larger  and  darker  par- 
ticles, which  is  evidently  the  case  with  the  sand 
north  of  Spanish  creek.  In  the  vicinity  of 
Grey  town,  owing  to  the  peculiar  conformation 
of  the  shore,  the  greatest  deposit  of  sand  occurs, 
within  the  85  miles  of  coast  that  my  reconnois- 
sance  covered.  This  deposit  or  at  least  the 
greater  part  of  it  is  from  the  sand  delivered  to 
the  coast  through  the  channels  of  the  San  Juan 
river  delta,  as  may  be  verified  by  its  identifica- 
tion with  that  found  in  the  San  Juan  river,  both 
31 


as  to  its  color  and  its  coarseness,  and  by  its  dis- 
similarity in  those  respects  to  the  sand  found  in 
other  vicinities.  That  any  of  the  San  Juan 
river  sand  has  drifted  southward  was  not  appar- 
ent, but  all  the  evidence  indicates  that  the  gen- 
eral movement  of  the  sand  is  to  the  northward. 
In  the  vicinity  of  Greytown  this  is  apparent.  At 
Colorado  bar  the  shore  is  being  washed  away 
on  the  north,  and  is  filling  up  on  the  south  side 
of  the  river.  At  Turtle  Bogue  we  have  the 
same  conditions.  About  a  year  ago  about  three- 
quartei*s  of  a  mile  of  the  tongue  of  land  at  that 
place  was  washed  awav  bv  a  river  freshet  and 
the  two  islands  or  shoals,  shown  upon  the  map, 
were  formed  in  the  early  part  of  last  month.  At 
Parasmina  again  we  have  the  same  building  up 
of  the  shore  on  the  south  side  of  the  mouth  of 
the  Reventazon  river,  if  not  the  washing  away 
of  the  north  side.  In  regard  to  what  has  taken 
place  previously,  the  indications  are  that  the 
mouth  of  the  California  river  if  not  also  that  of 
the  Reventazon  river,  was  at  Ilaulover  forming 
a  long  tongue  of  land  pointing  northward,  the 
natural  results  of  a  northward  drift  of  sand  at 
the  mouth  of  a  river.  At  Turtle  Bogue  we  have 
a  similar  tongue  of  land  pointing  northward,  and 
there  is  a  tradition  of  the  Indians  that  at  one 
time  the  Turtle  Bogue  river  emptied  into  the  sea 
at  what  is  now  known  as  Cuatro  Esquinas.  At 
Colorado  bar  we  doubtless  have,  as  I  have  pre- 
viously stated,  the  former  channels  of  the  Colo- 
rado river,  now  known  as  Simon  and  Agua  Dulce 
lagoons,  both  pointing  northward,  besides  this, 
further  inland  we  have  an  abrupt  turn  to  the 
northward  by  both  the  Colorado  and  the  San 
Juan  rivers.  This  change  in  direction  may  or 
may  not  have  been  produced  by  the  same  cause, 
but  there  is  nothing  in  the  topography  of  the 
country  to  make  it  improbable.  This  northward 
movement  of  the  sand  in  my  opinion  is  entirely 


482 


NICARAGUA  CANAL  COMMISSION 


due  to  the  nortliward  shore  eurrent  or  eddv  from 
the  southward  ocean  current,  the  sand  being 
kept  more  or  less  in  suspension  by  the  waves  and 
breakers. 

North  of  the  Indian  river  the  conditions  to 
some  extent  are  reversed  and  appear  to  contra- 
dict the  foregoing.  In  going  northward  the 
sand  upon  the  shore  diminishes  verv  perceptibly 
but  seems  to  extend  further  into  the  sea  than  it 
does  further  south.  Xorth  of  Spanish  creek  the 
beach  is  very  low,  flat  and  compact,  the  sand  is 
very  much  lighter  in  color  and  finer  in  gi*ain 
than  that  near  Grevtown,  but  evidentlv  of  tlie 
same  material,  the  darker  and  larger  pai'ticles 
having  been  separated  from  it  and  lodged  else- 
where. This  sand  from  my  own  observations, 
extends  as  far  north  as  Poijit  of  Rocks,  and  I  am 
told  that  the  same  sand  is  to  be  found  along  the 
coast  above  Gorda  point  but  in  a  still  less  quan- 
tity. This  proves  that  tlic  sand  continui^s  to 
move  northward  as  far,  at  least,  as  tlio  last 
named  place,  but  between  Point  of  Rocks  and 
Com  river  the  shells  upon  the  shore  seem  to  in- 
dicate a  southward  drift. 

On  going  northward  from  a  few  shells,  mostly 
fragments,  they  increased  in  number  and  per- 
fection until  I  came  to  a  bod  of  live  shells;  im- 
mediately above  this  bed  of  live  shells  there  was 
to  be  seen  nothing  but  a  few  fragments  of  shells. 
The  coral  seemed  to  bear  the  same  evidence. 
At  Round  Hill  there  is  a  coral  formation,  and 
the  only  place  that  I  found  any  fragments  of 
this  substance  is  between  Round  Hill  and  a 
point  about  one  mile  south  of  Indian  river.  The 
evidence  of  the  rivers  is  as  foUo^vs:  At  their 
mouths;  Indian  river,  a  northward  movement  of 
sand;  Spanish  creek,  a  southward  movement; 
Com  river,  both  directions,  but  the  more  recent 
is  southward;  Smart  creek,  southward.  Further 
inland,  it  may  be  seen  by  the  map  that  Indian 


river  and  Spanish  creek  indicate  decidedly  a 
southward  drift  of  sand  by  the  long  tongues  of 
land  pointing  southward  that  separate  them 
from  the  sea.  Spanish  creek  at  one  time  had  a 
much  longer  tongue  intervening  between  it  and 
the  sea,  for  the  evidences  are  that  it  at  one  time 
had  tlio  Haulover  lagoon  for  its  channel  and 
Haulover  for  its  entrance  into  the  sea ;  Corn  river 
bevond  its  mouth  lias  not  been  influenced  bv  the 
shifting  sand  in  the  sea;  Smart  creek  being  a 
small  stream  hugging  the  foot  of  the  hills  as  far 
as  I  could  see  it,  I  did  not  investigate  it  further 
than  the  imnu^iliate  vicinitv  of  its  mouth.  These 
conflicting  evidences  of  the  direction  in  which 
the  sand  is  drifted  mav  be  accounted  for  as  fol- 
lows:  By  referring  to  the  map  it  will  be  seen 
that  the  coast  line  between  Harbor  Head  and 
Gorda  point  forms  quite  a  bay,  and  the  northward 
shore  current  would  naturally  have  a  tendency 
to  take  a  direct  course  between  the  last  named 
points,  leaving  the  water  near  the  shore  more 
or  less  dead.  This  current  would  take  with  it 
such  sand  as  may  be  held  in  suspension  until  the 
waves  produced  by  the  prevailing  northeast 
winds  would  drive  it  to  the  shore.  These  waves 
facing,  say,  S.  45°  W.  striking  the  shore  whose 
direction  is  from  south  to  S.  30°  E.  would  make 
an  angle  of  from  15°  to  45°  with  the  shore,  di- 
verging to  the  southward,  thus  tending  to  wash 
the  sand  along  the  coast  in  that  direction.  This 
action  of  the  weaves  upon  the  sand  is  very  per- 
ceptible in  the  vicinity  of  Grey  town  where  the 
direction  of  the  coast  is  east  and  west;  the  diver- 
gence of  the  angle  that  it  makes  with  the  waves 
is  to  the  northward  and  westward  and  the  move- 
ment of  the  sand  is  in  the  same  directions. 
Further  south,  where  the  direction  of  the  coast 
is  practically  the  same  as  that  between  Grey- 
town  and  Point  of  Rocks,  it  might  be  expected 
that  the  same  result  would  occur,  but  south  of 


APPENDIX  X.— REPORT   OF  A.   ONDBRDONK,   ASSISTANT  ENGINEER  433 

Harbor  Head  tlie  nortliward  shore  current  is  there  is  a  conflict  between  these  two  forces  south 

close  to  the  shore  and  is  probably  the  stronger  of  Harbor  Head  seems  to  be  manifest  from  the 

of  the  two  forces  acting  upon   the  sand  and  irregular  and  chopped  up  condition  of  the  shore 

directs  their  resultant  to  the  northward.     That  that  is  not  found  northward  from  that  point. 


APPENDIX  XI 


REPORT  OF  L  HANKINS 

Assistant  Engineer 


CONTENTS 


PAGE 

489 


Journey  to  Ochoa 

San  Francisco  Valley  Survey 489 

Rio  Negro  Valley  Survey 489 

Work  in  Greytown  Office 490 

Character  of  Material  to  be  Excavated 490 

Estimates 490 

Nomenclature  of  Routes 490 

Line  North  of  Lake  Silico 490 

Various  Estimates .' .  492 

Estimate  for  the  Railroad 492 


APPENDIX  XI 


Washington,  D.  C,  May  5,  1899. 

Mr.  E.  S.  Wheeleb, 

Chief  Engineer,  Nicaragua  Canal   Commis- 
sion, Washington,  D.  C. 

Sir: — As  requested  in  your  letter  of  Febru- 
ary 28,  1899,  I  have  the  honor  to  submit  the 
following  report  of  my  operations  while  engaged 
with  the  Nicaragua  Canal  Commission  of  1897- 
1899. 

I  was  engaged  as  an  engineer  on  April  18, 
1898,  and  was  directed  to  report  to  you  at  once 
at  Greytown,  Nicaragua.  I  proceeded  to  New 
York  and  took  passage  on  the  steamer  "  Alene," 
leaving  April  23,  1898,  with  Messrs.  Hughes, 
Collins,  John  Stockton,  Durham  and  A.  S. 
Miller.  After  a  pleasant  trip  of  fourteen  days, 
stopping  at  Kingston,  Jamaica,  and  Savanilla, 
Colombia,  I  arrived  in  Greytown  May  6,  1898, 
and  reported  to  you  for  duty. 

I  was  assigned  to  duty  with  Mr.  H.  H. 
Trundle,  who  was  then  located  near  Ochoa.  I 
remained  in  Greytown  two  days  getting  neces- 
sary camp  outfit.  I  then  proceeded  up  the  San 
Juan  river  with  Dr.  C.  W.  Hayes  and  Mr.  A.  P. 
Davis  in  a  twenty-foot  canoe  loaded  with  pro- 
visions, with  three  men  to  paddle.  We  were 
four  days  making  the  trip  from  Greytown  to 
Ochoa.  On  account  of  the  low  water  in  the 
San  Juan  river  it  was  necessary  to  get  out  of  the 
boat  repeatedly  and  push  it  over  sand  bars, 
which  necessarily  made  the  trip  a  slow  one. 

32 


The  first  night,  we  camped  in  Mr.  Ondeiv 
donk's  old  camp  about  eight. miles  from  Grey: 
town,  where  we  were  greeted  with  the  usual 
rain  storm  and  a  full  quota  of  mosquitoes.  The 
second  night,  we  camped  in  a  native  ranch  on 
Paraiso  island.  The  third  day,  we  stopped  at 
the  Sarapiqui  river,  where  I  assisted  Mr.  Davis 
in  gaging  the  river  while  the  boatmen  dried  oux 
bedding  and  Dr.  Hayes  made  a  sail  of  cheeser 
cloth,  with  which  we  proceeded  more  rapidly  up 
the  San  Juan  and  camped  the  third  night  at 
Maineri's.     The  fourth  day,  we  reached  Ochoa, 

The  preliminary  survey  for  a  low-level  canal 
was  then  started  from  Ochoa  to  Greytown,  Mr^ 
Trundle,  chief  of  party.  I  ran  the  transit  and 
took  topography  from  the  Danta  Divide  to  4 
point  just  east  of  the  San  Francisco  hills,  a  dis- 
tance of  ten  miles,  and  developed  the  topography 
for  a  distance  of  two  to  three  thosuand  feet  on 
each  side  of  the  center  line.  At  the  east  side 
of  the  San  Francisco  hills  we  joined  the  line  run^ 
by  Mr.  Boyd  Ehle. 

On  August  5, 1898,  we  moved  camp  down  the 
San  Juan  river  three  miles  below  the  mouth  of 
the  Sarapiqui,  and  ran  the  preliminary  line 
from  the  east  slope  of  the  Sarapiqui  ridge  down 
the  Rio  Negro  valley  a  distance  of  six  and  one 
half  miles,  developing  the  topography  about  one 
thousand  feet  on  each  side  of  the  line.  This 
line  joined  the  line  run  by  Mr.  Evans'  party. 

We  then  moved  camp  just  below  the  Boca 
Colorado  and  developed  some  topography  in  the 


490 


NICARAGUA   CANAL  COMMISSION 


Silico  hills  along  the  Pacific  and  Caribbean  rail- 
road. 

On  August  25,  1898,  we  moved  camp  to  Grey- 
town.  From  this  date  to  September  15,  the 
party  were  engaged  in  making  maps  and  profiles 
of  lines  nm. 

Although  it  rained  nearly  every  day  while  we 
were  on  the  survey,  the  party  did  not  lose  a 
single  day  off  the  line  and  only  twice  were  we 
compelled  to  stop  work  on  account  of  rain  pre- 
venting seeing  through  the  instruments.  I  used 
one  transit  all  the  time,  and  although  it  was  wet 
every  day,  it  kept  in  perfect  adjustment. 

While  making  the  survey  and  taking  the  to- 
pography, I  naturally  took  note  of  the  character 
of  material  along  the  line.  Through  the  ridges 
the  soil  was  of  a  clavcv  character  and  of  such 
consistency  as  would  require  a  slope  of  one  to 
one.  Through  the  swamps  I  should  say  from 
two  to  six  feet  deep  was  mud  and  decayed  vege- 
table matter,  below  this  a  compact  mass  of  fine 
silt,  which  will  probably  require  a  slope  of  two 
to  one,  although  we  noticed  the  banks  of  the 
watercourses  through  this  material  were  nearly 
vertical  from  ten  to  fifteen  feet  high.  Very 
little  rock  showed  on  the  surface  at  any  point, 
in  fact  at  no  place  except  along  the  ridge  just 
c  east  of  San  Francisco  river,  and  here  onlv  in 
boulders  of  a  volcanic  character  in  the  streams. 

The  material  was  such  that  if  it  were  in  the 
States  it  would  not  be  classified  at  a  higher  price 
per  cubic  yard  than  is  applied  to  the  usual  run 
of  material  consisting  of  rock,  soft  rock,  clay, 
sand  and  silt,  which  prices  usually  run  eighty, 
forty,  twenty-five  and  twenty  cents  per  cubic 
yard.  To  these  prices  a  per  cent,  should  be 
added  on  account  of  climatic  conditions  in  Nica- 
ragua, the  principal  of  which  is  the  excessive 
rainfall  on  the  east  side,  an  average  of  twenty- 
one  feet  a  year.     The  distance  from  base  of  sup- 


plies will  also  have  to  be  considered.  I  should 
think  sixty-five  per  cent,  would  be  a  large  esti- 
mate to  add  to  the  cost  of  each  of  these  materials 
except  where  hard  rock  is  encountered  below  the 
swamp  level  and  in  lock  excavation. 

On  September  IG,  I  sailed  from  Greytown  on 
the  steamer  "  Altai  "  in  company  with  yourself 
and  several  others  of  the  Commission,  for  Xew 
York,  arriving  there  September  28,  and  left  im- 
mediately for  Washington  where  offices  were 
engaged  and  work  commenced  on  estimates  for 
the  canal. 

On  October  11,  I  was  put  in  charge  of  one  of 
the  rooms  as  assistant  engineer  and  have  been 
engaged  ever  since  projecting  locations  and 
working  up  estimates  for  a  low-level  canal  line 
from  the  Caribbean  sea  to  a  point  twenty-two 
and  three-tenths  miles  west,  where  Mr.  Tnmdle's 
work  begins. 

I  have  made  locations  for  five  different  routes 
and  worked  up  estimates  of  quantities  for  six- 
seven-  and  eight-lock  systems  on  each  line. 

The  lines  are  noted  as  follows:  Line  north 
of  Lake  Silico,  Lull's  Variant  I,  line  through 
Lake  Silico,  Lull's  Variant  II,  line  south  of  Lake 
Silico  from  Grevtown,  Lull's  Variant  III,  line 

»<  7 

south  of  Lake  Silico  from  Harbor  Head,  LulFs 
Variant  V,  line  from  sea  at  Agua  Dulce  lagoon 
along  the  lower  San  Juan  river.  Lull's  Variant 
IV. 

These  projected  lines  and  estimates  were  made 
from  a  careful  study  of  all  preliminary  surveys 
that  were  made  in  this  territory  by  this  Com- 
mission and  all  data  from  other  sources. 

I  recommend  Variant  I,  the  line  north  of 
Lake  Silico,  which  is  located  as  follows:  Com- 
mencing at  the  seven-fathom  curve  in  the 
Caribbean  sea  northwest  of  the  Greytown  light- 
house, crossing  Greytown  lagoon  in  its  deepest 
water  and  entering  the  mainland  three  thousand 


APPENDIX   XL— REPORT   OF  L.   HANKINS,   ASSISTANT   ENGINEER 


491 


feet  south  of  La  Fe  or  seven  hundred  feet  south 
of  the  Maritime  Canal  Company's  route,  running 
thence  south  49°  30'  west  through  the  coastal 
plain,  crossing  the  Rio  San  Juanillo  and  the 
Rio  Misterioso,  passing  about  two  miles  north 
of  Lake  Silico,  crossing  the  first  spur  of  ridges 
from  the  Silico  hills  five  and  one-half  miles 
from  the  sea  where  the  first  lock  is  located, 
then  along  the  Rio  Misterioso  valley  the 
same  course  for  a  distance  of  one  and  one-quarter 
miles,  tlien  a  0°  30'  curve  to  the  left  for  one 
and  one-quarter  miles,  then  south  18°  26' 
west  for  a  distance  of  five  and  two-tenths  miles, 
crossing  the  main  ridge  from  the  Silico  hills 
nine  and  one-quarter  miles  from  the  sea,  where 
the  second  lock  is  located,  then  again  along  the 
Rio  Misterioso  valley  crossing  the  Rio  Pescado 


near  its  mouth,  then  along  the  south  bank  of 
the  Rio  San  Juanillo,  crossing  this  river  the  sec- 
ond and  last  time  at  a  distance  of  fourteen  and 
two-tenths  miles  from  the  sea.  Here  the  line 
curves  to  the  right  on  a  1°  0'  curve,  four 
thousand  one  hundred  and  twenty-eight  feet 
long,  and  enters  the  valley  of  the  Rio  Negro, 
then  along  the  valley  of  the  Rio  Negro  to  the 
east  slope  of  the  Sarapiqui  ridge  where  my  line 
joins  Mr.  Tnmdle's  line.  The  third  lock  is 
located  in  a  ridge  on  the  Rio  Negro  valley  nine- 
teen and  seven-tenths  miles  from  the  sea.  The 
length  of  this  line  north  of  Lake  Silico  from  the 
seven-fathom  curve  to  the  east  slope  of  the  Sara- 
piqui ridge  is  twenty-two  and  three  hundred  and 
twenty-four  thousandths  miles.  The  approxi- 
mate estimate  for  a  six-lock  system  is  as  follows: 


Dredging,  sand  and  silt,  21,900,000  cubic  yards  at  37ff $8,103,000 

Canal  section,  dry  excavation,  1,030,600  cubic  yards  at  37^ 381,322 

Diversion,  Rio  San  Juanillo,  476,000  cubic  yards  at  37^ 176,120 

Canal  section,  dry  excavation  soft  rock,  787,600  cubic  yards  at  93^ 732,468 

Canal  section,  dry  excavation  hard  rock,  281,900-cubic  yards  at  93^ 262,167 

Greytown  breakwater,  stone,  550,000  cubic  yards  at  $1.75 962,500 

Rio  Negro,  waste-weir  dry  excavation,  410,000  cubic  yards  at  37^ 151,700 

Rio  Negro,  waste-weir  masonry,  2770  cubic  yards  at  $8.30 22,991 

Lock  No.  1,  waste-weir  dry  excavation,  26,000  cubic  yards  at  37^ 9,620 

Lock  No.  1,  waste-weir  masonry,  250  cubic  yards  at  $8.30 2,075 

Two  locks,  1^.4  lifts  at  $1,577,000 3,154,000 

One  lock,  18.4  lifts  at  $1,675,400 1,675,400 

Stone  pitching  on  embankments,  120,000  square  yards  at  $2 240,000 

Clearing  1500  acres  at  $75 112,500 

Piers  at  Greytown  Harbor,  5500  lin.  feet  at  $150 825,000 

Grubbing  750  acres  at  $100 75,000 

Total $16,885,863 

Sheet  piling  at  stream  crossings  1,440,000  B.  M 86,400 

Puddle  embankments,  890,000  cubic  yards  at  $1 890,000 

Total $17,862,263 


492 


NICARAGUA  CANAL  COMMISSION 


The  last  two  items,  sheet  piling  and  puddling, 
have  been  added  at  the  suggestion  of  Colonel 
Peter  C.  Hains,  where  the  head  of  the  water  in 
the  canal  is  over  twelve  feet  against  embank- 
ments. 

The  material  from  the  canal  excavation  is  dis- 
posed of  by  depositing  along  the  canal  in  em- 
bankments; and  where  the  canal  is  in  embank- 
ments the  canal  excavations  will  make  a  bank 
eight  feet  above  the  surface  of  the  water  and 
not  less  than  iifty  feet  wide,  and  generally  a 
much  greater  width  than  this.  The  embank- 
ments are  also  estimated  to  be  from  eight  to 
twelve  feet  higher  than  the  highest  high  water 
in  the  San  Juan  river. 

As  a  practical  question,  I  think  building  a 
canal  through  this  section,  amounts  to  nothing 
more  than  handling  this  volume  of  material  un- 
der the  conditions  noted  above,  which  can  be 
overcome  by  adding  a  per  cent,  to  the  cost  of 
similar  work  in  the  States. 

Besides  the  five  projected  locations  and  esti- 
mates mentioned  above,  I  have  also  made  esti- 
mates of  quantities  on  the  line  north  of  Lake 
Silico  for  a  five-lock  system,  and  on  the  same 
line  for  a  six-lock  system,  width  on  bottom  one 
hundred  feet. 


I  also  made  estimates  of  quantities  on  the 
river  section  from  Boca  San  Carlos  to  Purgato- 
rio  rapids,  distance  seventeen  miles,  for  a  low- 
level  canal  six-lock  system  of  three  dams  in 
river,  and  worked  this  section  the  second  time, 
lowering  the  grade  five  feet. 

I  have  also  projected  a  railroad  location  along 
the  proposed  low-level  canal  line  from  the  Carib- 
bean sea  to  Toro  rapids,  distance  seventy-eight 
miles,  and  from  Lake  Nicaragua  to  the  Pacific 
ocean  at  Brito,  a  distance  of  seventeen  and  one- 
half  miles,  and  made  profiles  and  estimates  of 
quantities  and  cost  of  the  projected  railroad. 
The  railroad  is  located  directly  along  the  canal 
route  from  two  hundred  to  one  thousand  feet 
froih  the  center  line.  There  is  nothing  imprac- 
ticable in  connection  with  it,  and  it  amounts  to 
nothing  more  than  simple  railroad  construction. 

I  have  had  to  assist  me  in  this  work  one 
draughtsman  and  two  computers. 

All  the  maps,  profiles,  cross  sections  and  note 
books  showing  the  lines  I  have  projected  and 
made  estimates  on,  are  filed  with  the  Commis- 
sion. 

Very  respectfully, 

L.  Hankins, 
Assistant  Engineer. 


INDEX 


Acoyapa  river   216 

Act  authorizing  commission xi,  1,  2 

Additional  waste-ways  68 

Additional  work  required   182,  369 

Adee,  Alvey  A.,  Acting  Secretary  of  State xi 

Administration,  cost  of  44 

Agua  Dulce  lagoon 98 

Agua  Dulce  route 77 

Agua  Muerta    7,  8,  24,  59,  150,  226,  365 

Ahrling,  Alfred  52,  216,  243,  246.  251 

Ajocuapa  river    215 

"  Alert  '*  U.  S.  Steamship 1,  5.  53.  471 

Alligator  river  214 

Alluvial  formations  122 

Alluvial  plains 97 

AUuviation    143 

Alluvium    13,  16,  153 

Amapalo  river 216 

Andesite    120 

Animal  life  399 

Anschutz,  H.  E 52,  413,  415 

Application  of  geologic  facts  to  engineering  prob- 
lems   152 

Arana  river    214 

Archambault,  T.  J.  H 51,  93 

Area  of  canal  cross-sections 17 

Army  building.  New  York  1,  5 

Atkins,  Thomas  B 391 

Atlas  Steamship  Co 39,  425 

Atmospheric  conditions  12,  370,  439 

Augite  andesite   120 

Austin,  J.  A 52 


Baldwin.  D.  H 51,  198 

Barca  lagoon  98 

Barnard,  J.  H 52,  405 

Barton,  W.  M 51,  219,  256 

Basalt  15,  120,  126,  157 

Base  lines 363.  409,  423,  479 

Begien,  R.  N 52,  374,  375.  379 

Belin,  Director  General,  Panama  4 

33 


Belknap,  P.  H 51,  352 

Benches    2,  435,  441,  443 

Bernstein,  Lester   51,  370,  374 

Bernstein,  Moriz  51,  93,  94,  427 

Blue  clay   129 

Bluefields  rainfall   262,  281 

Board  of  1895..  12,  25,  30,  31,  35,  61,  134,  165,  260,  262 

Boca  San  Carlos  dam 24,  27,  33,  34,  45,  80,  169 

394,  397,  427,  429,  430 
Boltz,  Thomas  F...52,  400,  406,  411,  413,  415,  418,  427 

Boring  operations,  extent  of  161 

Borings,  Canal  Company's  162 

Borings,  instructions  regarding 2 

Breese,  R 51,  228 

Brito  6.  15.  350,  353 

formation    114,  156 

harbor   1,  24,  31,  36,  164 

hydrographic  station   198 

mean  sea  level  2,  470 

rainfall 264 

temperature  and  humidity  304 

tide  gages  470 

tide,  mean  rise 31,  470 

Brown,  George  W.,  Ass't  Eng'r 51,  52,  423 

Brune,  P.  J 51,  400 

Buen  Retiro  15,  23,  35,  45.  163,  166 

Bull,  J.  A 51,  202,  352 


Cabeza  river  216 

Camastra  river   216 

Camp  Barton   ; 257 

rainfall    276 

temperature  and  humidity 332 

Camp  building 393,  406 

Camp  Caldera,  rainfall 265 

Camp  No.  7 257 

Canal  Belt   54,  349,  369 

Canal  Co.  ...5,  17,  25,  30,  31,  33,  36.  53.  61,  64,  70,  72 
120,  127,  162,  164,  165,  170,  171,  172,  175,  176 
177,  179,  182,  260,  278.  281,  348,  351,  353.  354 
391,  392.  393,  399,  405.  407,  415,  441,  445,  449 
450,  456,  466,  471,  472,  473,  474,  479. 


494 


INDEX 


Canal  Co.,  bench  in  machine  shop  . .  .340,  393,  445,  479 

borings  162 

railroad   392 

route   25,  26,  51,  72,  353,  354,  392 

Canalization  of  the  upper  San  Juan 63 

Canal  region    54,  349,  369 

Cafias  Gordas  creek  349,  351 

Cafiitas  river 216 

Cafio  Bravo  8,  60,  363,  365 

Caribbean  and  Pacific  Transit  Co 39,  425 

Carmichael,  John   52,  411,  413,  418,  440,  479 

Cartego    136 

Carter,  Captain  O.  M.,  Member  of  Commission . . .  xi,  1 

Carter,  M.  P 40 

Cascabel  creek  143,  349,  351 

Cascajo   127,  132,  156,  163 

Castillo    8.  34,  56,  167,  364 

hydrographic  station  223 

rainfall    271 

Catrina  river   215,  216 

Central  American  prices    38,  71 

Chacalapa  river   143 

Challice  George   52,  210 

Chanchos  river   27,  35,  172,  243,  250,  261 

Chicago  contractors 410 

Chicago  drainage  canal   37,  38,  45,  46,  70 

Chief  Engineer   2,  47 

Chief  of  Engineers,  U.  S.  A 5 

Chllds,  Col.  O.  W 14.  24,  31,  260 

Childs  route  24,  70.  165 

Childs   route   variants 45,  70,  73,  74,  75,  79,  81 

83,  353.  354,  355 

Classification  and  weathering 16 

Classification  of  materials 153 

Classification  of  topographic  features  95 

Clay  14,  128 

Clay,  residual 155 

Clay-silt 153 

Climate    12,  111,  112,  113,  193,  368,  374,  398,  427 

Climie,  William  262,  278 

Coal    117 

Coast  Survey 5,  441 

Cole,  Dr.  S.  M 349 

Collins,  H.  F 52,  479,  489 

Colombia  prices  40 

Colorado  river 8,  60.  152,  260,  363 

Comalcaqua  creek  349 

Commissary  department 1,  .427 

Commission,  appointed   xi,  xii 

arrived  in  Greytown   1 

Colon  visited 4 

examination  of  eastern  divide 4 

examination  of  San  Juan  river 3 

Fort  San  Carlos  visited 4 

Granada  visited  3 


Commission,  Greytown  visited  4 

Managua  visited  3 

Ochoa  visited   4 

Panama  line  examined  4 

Port  Limon  visited 4 

return  to  the  United  States 4 

Rivas  visited    4 

route  chosen   45 

sailed  from  New  York 1 

San  Jos6  visited  4 

Conchuda  dam  34,  168 

Conditions  favoring  rock  decay 125 

Conglomerate  120,  121,  127,  138,  139 

Congrejal  river  216 

Connelly,  Michael  A 405 

Consuelo  river  ': 214 

Continental   divide    5,  55,  101,  142,  145,  350,  353 

Contingencies   44 

Cooley,  Lyman  S 38,  70 

Copalchi  creek 412 

Coroalles,  M.  A 51,  349,  352 

Coseguina  volcano  109 

Cost    43,  46 

Costa  Rica  rainfall  283 

Cost  of  excavating  hard  rock 160 

Crowninshield,  J 52 

Cucaracho  river 214 

Cureflo  creek   123,  171,  408 

Current  meters  197 

Curvature,  maximum 16,  354,  355,  398 

Cut-offs   3,  10.  63,  378 


Dacite    15,  28,  120,  126,  157,  158 

DaU,  Dr 117,  119 

Damages  from  raising  Lake  Nicaragua 373 

Dams    32,  33,  35,  78,  167,  184,  396 

three  compared  with  one 29,  34,  80,  380 

Danta  river   ....8,  27,  123,  172,  178,  243,  261,  394,  397 

Datum  plane 2,  440,  442 

Davis,  Arthur  P.,  Hydrographer.  .5,  51,  52,  54,  64,  65 

85,  94,  353,  376,  415,  423,  427,  489 

report  by  193 

Davis,  F.  H 52,  348,  352 

Davis,  F.  P.,  Ass't  Eng'r 52,  411 

Davis,  Fred 52,  204,  216,  348,  352 

Delta  plain   29,  61,  97,  122,  151,  365 

Depression-recent    143 

Depth  of  canal  16 

Deseado  river   27,  256,  261 

hydrographic  station    256 

rainfall   276 

temperature  and  humidity  332 

Dimensions  of  canal   16,  46 


INDEX 


495 


Dimension  stone  15 

Dimension  timber 14 

Director  of  the  Geological  Survey 5 

Discharge  of  streams  197 

Disintegration,  rock   125,  132,  157 

Dissection,  peneplain 100,  140 

Distances  along  the  canal  route 17 

Divide,  continental   5,  55.  101,  142,  145,  350,  353 

Divide,  eastern   27,  28,  40,  74.  105,  107,  170 

Divide,  Lake-Caribbean   107 

Divide  near  Castillo  150 

Divide,  western 23,  106,  165 

Drilling  operations   93 

Drill  outfits   427 

Dry  season  18,  111,  262 

Dutton,  Major   13,  132,  137 

Durham.  H.  W '. 52,  254,  413.  415,  418,  489 

E 

Early  tertiary  deposition 138 

Earthquakes  13,  53,  58,  132,  357 

Eastern  divide    27,  28,  40,  74.  105,  107,  176 

Eastern  division  7,  24,  26 

East  side   58 

Ehle,  Boyd   51,  85,  391,  394,  489 

report  by  401 

El  Carmen  349 

Elevation  of  peneplain  102,  139 

"  El  93  "  Lake  steamer 374,  375 

El  Pavon 349 

Elson,  J.  C 52,  257,  406,  410,  411,  412 

El  Toro  river 214 

Embankment  creek 177,  393.  397 

Embankments    32.  35,  171,  395,  396 

Employes,  list  of  51 

Engineering,  cost  of 44 

Engineering  staff  engaged   1 

Espinal   7,  348 

Espinola,  Ramon   278 

Estimate  for  a  canal  100  feet  wide 83 

Estimates   43,  46,  70,  378,  430,  491 

Estimates,  value  of  2,  84,  161,  296,  369,  379 

Evans.  P.  W 400 

Evans,  S.  S 51,  85,  370,  382,  394,  473,  489 

report  by  419 

Evaporation   18.  19,  283 

Excavation  lines,  additional  bore  holes 182 

Childs  route 165 

eastern  division 173 

Exchange,  rate  of 39 


Factors  determining  cost  of  rock  excavation 160 

Feasibility    xi,  42 


Field  work   45,  84 

Fisher,  E.  F 51,  93 

Fitzgerald    *. 52,  479 

Flint,  Dr.  Earl 278,  279,  293,  296 

Flood-plains    99,  238 

Florida  lagoon   27,  35,  98,  154,  172,  178,  394,  397 

Fluctuations  in  lake  level 17,  58,  64,  291,  372 

Food  supply   39,  355.  428 

Forster,  J.  D 51,  352 

Fort  San  Carlos   4 

base  line    423 

evaporation    287 

gages  467 

hydrographic  station 211 

rainfall   268 

temperature  and  humidity  315 

Fragmental  igneous  rocks 121 

Freight  over  ocean  routes 64 

Friederichsen,  Louis  480 

Frye,  W.  C 400 

Fuel 14,  356 

a 

General  estimate  of  cost  43 

General  geologic  work  94 

Geological  Survey,  U.  S 5,  51 

Geologic  details  162 

Geologic  history  137 

Geologic  report 87 

Part  I    95 

Part  II    152 

Part  III    184 

Scope  of  94 

Geologic  sections  161 

Geology   52,  87 

Gill,  Dr.  Theodore   146 

Glenny,  F.  D 52 

Gonzales  river   143,  216 

Gorge  cutting  140 

Grade   68,  395 

Granada  rainfall    262,  280,  281 

Green,  F.  C 51,  204 

Greytown    1,  4 

evaporation  290 

harbor    1.  2,  29,  36.  41,  61,  479 

headquarters 425 

mean  sea  level  2,  441 

rainfall    262.  263.  277,  281 

temperature  and  humidity .336 

tide  gages   441 

Guacalita   216 

Guachipilin  river 143 

Guarumo  creek 349 

Guatemala  prices  40 

Guiscoyol  creek 142,  143,  259,  350,  353 


49G 


INDEX 


Haciendas  river   214,  216,  217 

Hague,  Mr 181 

Hains,  Colonel  Peter  C,  Member  of  Commission.. 

xii,  1.  5,  46,  411,  492 

Hammond,  C.  L 51,  374 

Hanklns.  L.,  Ass't  Bng'r 52,  85,  400 

report  by  485 

Hanus,  Lleut^.  G.  C.2,  4,  53.  211,  347,  363,  378.  392,  413 

Harbor  Head  30,  479 

Harden,  E.  B.,  Ass't  Eng'r 51,  349,  352,  357 

Hardness  of  stone 158,  160 

Hard  rock  158,  160 

Harris,  Stephen.  Ass't  Eng*r 52,  85,  393 

report  by 431 

Haupt,  Professor  Lewis  M.,  Member  of  Commis- 
sion   xi,  xli,  1,  46,  65 

Hayes,  C.  W.,  Geologist 5.  12,  13.  14,  15,  16,  35,  51 

52,  54.  61,  68,  85,  87,  237.  351,  378,  395,  399,  489 

report  by  87 

Hayman,  Charles    52.  229,  243.  216,  250,  251 

Headquarters  1,5 

Health   12,  355,  418.  425 

Herbert.  W.  E 51.  93 

Heyl,  E.  G 52,  406,  411 

High-level  location,  western  354 

Hill,  Robert  T 133 

Hlnes,  W.  D 400 

Houses    373 

Hubs    356 

Hughes,  Arthur  L 415,  489 

Humidity    304 

Humphrey.  E.  P 51,  93.  213.  352.  413.  415,  418 

Hurd.  H.  C 51,  52,  198.  352.  423.  427.  474 

Hurtado,  Ramon 440 

Hydrographic  report 193 

Hydrographic  stations 3,  5,  193 

Hydrology    51,  193 

Hypersthene  basalt   120 


Ibo  lagoon 98 

Iddings,  Mr 184 

Iglesias,  Rafael,  Pres.  Costa  Rica 4 

Igneous  rock  15,  119 

Indian  river 78,  479 

Intercontinental  R.  R.  Commission 41 

Irazu  volcano  133 

Iron  and  steel 14 


Jicoral  river  259 

Jinotepe  plateau  110,  124 

Johnston,  John  B    400 

Jones,  J.  0 52,  440.  441 

Juan  Davila  river 349 


Keasbey,  Professor 54 

Keith.  William  H 39 


Labor    

La  Cruz  river  .. 

La  F(5i    

La  Flor  dam   . . 

Lagoons   

I^ke  Apoya  . . 
Lake-Caribbean 
Lake  Division  . 
I^ake  Managua 


Lake  Nicaragua 


Jackson,  Hon.  W.  H 278 

Jamaica  negroes  399,  427 


....44,  352,  355,  368,  374,  399,  427,  429 

S 

405,  423.  479 

7,  25,  35,  45,  162,  349.  354 

30,  97 

110 

divide 107 

26.  371 

147.  298 

area   6,  208,  298 

contributes  no  water,  dry  years.. 293 

drainage  area 298 

elevation    6 

fluctuations  209 

value  as  a  reservoir 298 

5.  57.  201,  371 

anchorage    374 

area   6.  17,  21.  371 

area  below  sea  level 6 

bottom   371 

channel  378 

cost  of  lowering  one  foot 291.  298 

dimensions    6 

discharge   218 

discharge  and  fluctuation 22,  67 

drainage  area  6.  17.  202,  372 

elevation    6.  212 

elevation,  water  held  by  dam  at 

Savalos  221 

evaporation    58.  65,  283.  287,  291 

fluctuations  17,  58.  64.  291,  372 

formation  of 144 

formerly  part  of  Paciflc  ocean 5 

greatest  depth 57,  202 

inflow   17.  58.  213 

islands    372 

lockage,  leakage  and  power 66 

map    375 

maximum  discharge   239 

maximum  elevation    17.  291 

maximum  rise  in  48  hours 294 

minimum  elevation  17 


INDEX 


497 


Lake  Nicaragua,  old  river  channel 141 

outflow    58 

rainfall    66,  269,  293 

regulation  of  level.  17.  19,  64,  291,  375 

sailing  route  17,  58,  374,  379 

shore  line   373 

soundings    374 

spillway  capacity 20,  22 

storage  and  discharge  20,  21 

storage  capacity   375 

storms 373 

subsequent  modification 146 

survey    2.  3,  371 

temporary  storage  20 

tributaries  372 

variation  limits  22 

water  supply  291 

wave-cut  terrace  147 

waves   374 

Lake  Sllico  98,  423,  424 

rainfall   263 

Lakes,  small  97 

Land  values 356,  367,  374,  377 

Lannan.  Louis  E 52,  257.  440,  441,  479 

I^s  Lajas  116,  163 

evaporation  285 

gages   467 

hydrographic  station 202 

rainfall   265 

river.  6.  57,  106,  142,  215,  259.  349,  350,  353 

temperature  and  humidity  307 

Las  Lajas  river,  branch  of  the  Ochomogo 216 

Leary,  Neil  P 51,  244,  251 

Lee,  L.  R 51,  352,  405 

Length  of  canal   17 

Leutz,  Commander  E.  H 5 

Levels    370,  381,  431 

I-ievy ,  Pablo   163 

Limestone  115,  122,  138 

Limon  river  216 

Lindo  river 261 

Littoral  current    61 

Location   62 

Lockage   19,  66 

Locks    16,  42,  43,  71,  78,  80.  83,  183.  378.  395,  415 

Longitude  369 

Low  dams 29,  34.  80,  380 

Lower  Ochoa 33,  170 

Lower  San  Juan  river  60.  260.  479 

Low  level  line  3,  70 

Low  level  route,  western  353 

Lull,  Commander    25.  31,  143.  260 

Lull  routes 28.  70,  75,  173,  177.  417.  423,  490 

estimates  comparing  variants    76 

Variant  I.  estimate.  .45,  75.  80,  82.  83,  491 


Machado  river  8,  103,  177,  242,  397 

Machuca  dam    27,  28,  34.  167,  363,  366,  394 

formation    117,  156 

rainfall 272 

rapids    59 

river    8,  259 

sandstone    126 

Madera  island  6.  58,  109.  372,  374 

Maher,  W.  J 400 

Maineri's  pasture   409 

Majaste  river 216 

Malacatolla  river 108,  216,  217 

Managua  rainfall  280 

Map  No.  1,  Sheet  3 279 

Marabios  range  109 

Maria  river   214,  216 

Maritime  Canal  Co... 5,  17,  25,  30,  31,  33,  36,  53,  61,  64 
70,  72,  120,  127,  162,  164,  165,  170,  171,  172 
175,  176,  177,  179,  182,  260,  278,  281,  348,  351 
353,  354,  391,  392,  393,  399,  405,  407,  415,  441 
445,  449,  450.  456,  466,  471,  472,  473,  474,  479 

borings   162 

railroad 392 

route   25,  26,  51,  72.  353.  354,  392 

surveys  393 

Martinez,  Dion   51,  52,  400,  415,  473 

Masaya  rainfall   280 

Masaya  volcano  109 

Massive  igneous  rocks  120 

Materials  tor  structural  purposes 13 

Matinga  river  143 

McNeil,  L.  F 51,  400 

Mean  sea  level 2,  442,  470 

Medio  river  25.  143,  215,  216 

Melchora  river 8 

Members  of  commission  xi,  xii,  1 

Mena  river   214,  216,  217 

Menocal,  A.  G 25,  26.  27 

route    16,  26.  28,  34,  45,  70.  73,  79 

175.  392,  415 

Merriman,  Thaddeus  51,  370.  374,  375 

Meteorology   51 

Microscopic  petrography 184 

Middle  tertiary  uplift  and  erosion 139 

Miersch,  Bruno 136 

Miller,  A.  H 93 

Miller,  A.  S 52,  489 

Miller,  H.  C,  First  Ass't  Eng'r 52,  411,  412,  423 

Miller,  Harold  R 40 

Miller,  H.  W 51 

Minimum  radius   16,  354,  355,  398 

Misterioso  lagoon  415 

Misterioso  plain  181 

Mitchell,  J.  A 52,  440 


498 


INDEX 


Mitchell,  Professor 61 

Mohun,  L.  W 52 

Mollales  river    215.  216,  217 

Mombacho  volcano  109 

Momotombo  volcano  109 

Monkey  point  16 

Monongahela  improvement 41 

Monopolies    356 

Montez,  A.  V 52,  479 

Monthly  rainfall  277 

Monthly  reports  3 

Moore,  Hon.  Willis  L 278 

Morrin,  R 52,  220,  400 

Morrito  evaporation  286 

hydrographic  station   211 

rainfall  267 

Moyogalpa  374 

Murillo  river 214 

Murio  river 216 

N 

Narrow  canal  estimate  83,  379 

National  railway  of  Costa  Rica 39 

Naval  hydrographic  parties 2 

Navy  department 5 

Navy,  Secretary  of  the 1 

"  Newport  "  U.  S.  Steamship .1,  4,  5,  51,  53 

Nicaragua  Canal  Board 12,' 25,  30,  31,  35,  61 

134,  165,  260,  262 

Nicaraguan  depression  95 

Nicaraguan  government   3,  374,  375 

Nicaragua  revolution   4 

Nicewarner,  E.  G 51 

Nicholson  creek   35,  172,  244,  253,  261 

Nomenclature  of  routes 70 

Norris,  A.  J 51,  400 

Nueva  river 108,  206,  208,  298 

hydrographic  station    206 


Organization  of  parties  1,  51 

Oroci  river   214,  216,  217 

Orosi  volcano  132,  137 

Ortega,  Nicanor  348,  467 


Ochoa  dam   26.  27,  28,  33,  40,  169.  415 

evaporation 289 

hydrographic  station  8,  9,  232 

rainfall    274 

temperature  and  humidity  327 

Ochoa,  Leonidas  440 

Ochomogo  river  216,  217 

Ollate  river    215,  216,  217,  259 

Ometepe  island   3,  6,  109,  124,  137,  201,  372,  373 

Onderdonk,  Andrew,  Ass't  Eng'r 52,  85,  363 

report  by 475 

One  dam  or  three  dams 29,  34,  80,  380 

O'Reardon,   Ignatius   51,  93,  411 

Organization  of  commission 1 


Pacific  ocean,  mean  sea  level 470 

Pain,  A.  E.  L 52,  440 

Palo  de  Arco  creek 8 

Panama  Canal  Co 5 

Panama  canal  prices 37 

Panama  railroad    5 

Parada  creek 8,  60,  363,  365 

Parada  lagoon  98 

Paraiso    349 

Paso  Real  hydrographic  station 203 

rainfall    266 

Peneplain    96,  100,  140 

Peugnet,  C.  P.  E 51,  352 

Philip,  G.  P 51,  204.  210 

Physics    5,  54 

Physiography  of  the  canal  region 95 

of  the  San  Juan  valley 148 

Pica-pica    352 

Piedia  river   216 

Piedras  river    215 

Piling   14,  367 

Pisote  river    214,  216,  217 

Pittier,  Professor  H 279 

Plain,  costal   97 

delta  29.  61,  97,  122,  151.  365 

Plains,  alluvial  97 

Poco  Sol  river  8,  54,  101 

Poe  lock  35,  66 

Point  of  Rocks  16 

Police  system 356 

Ponderoso  river  216 

Port  Limon  rainfall 262 

Postal   System    356 

Post,  R.  B 52.  413,  415,  418.  440 

Post-Tertiary  elevation  and  gorge  cutting 140 

Precise  I^evels   2,  363.  393.  426,  431 

benches    435.  441.  443 

checks  with  other  lines 426,  471 

crossing  Lake  Nicaragua   466 

field  records  440 

final  reductions  440 

instructions  regarding  2 

instrumental  equipment 435 

length  of  line 474 

length  of  sights   438 

limit  of  error 439 

long  sights   437 

method  of  work  438 


INDEX 


499 


Precise  Levels,  organization  of  party  437 

probable  error  474 

rate  or  progress 436 

President  of  Commission  xi,  xii,  1 

President  of  Costa  Rica  4 

President  of  Nicaragua  3 

Prices   37,  42,  46,  70,  72,  84,  379,  425,  490 

Products  of  rock  decay  128 

Profiles  showing  geologic  conditions 152,  395 

Projects  and  Routes  24 

Puddled  core  necessary  13 

Pueblo  river  214 

Pumice  124 

Punta  Petaca  415 

Q     • 

Quantities    36,  43,  84 

Quebrada  Honda  208 

hydrographic  station 207 

B 

Radius,  minimum  16,  354,  355,  398 

Railroad  estimate  44,  492 

Rainfall 18.  53,  111,  262,  368 

average  in  basin  compared  with  Rivas...     6 

18,  293 

maximum  at  Rivas   6,  20,  21,  294 

minimum  at  Rivas   6,  19,  293 

Rainy  season 262 

Randolph,  Isham 38,  70 

Ransome,  F.  Leslie 119 

report  by  184 

Recent  alluvial  formations   122 

Recent  depression  and  allu viation 143 

Recent  geologic  history 137 

Recent  volcanic  rocks 123 

Red  Clay   128 

Reed,  H.  S 51,  213,  229,  235,  250 

Regulating  works  2.  63,  68,  355,  395,  426 

Regulation  of  lake  level 17,  19,  64,  291,  375 

Relative  cost  of  dam  projects 34 

Residual  day 16,  155 

Residual  hills    105 

Rio  Frio   8,  54,  101,  213.  214,  217 

Rio  Grande   6,  12.  32.  57.  106,  142 

145.  163.  198.  349.  350,  351.  353.  355 

hydrographic  station  198 

Rio  Grande,  flows  into  Caribbean  sea 108 

Rio  Limpio  27,  248 

Rio  Medio  route  353 

Rio  Negro 8,  180,  415,  417,  489 

Rio  Negro,  flows  into  Lake  Nicaragua 213 

Rio  Viejo 108,  203,  266,  298 

hydrographic  station 12,  203 

temperature  and  humidity  312 


Rivas  rainfall  264,  279.  293,  296 

plain   106,  144 

Roads   356 

Roberts,  Colonel  T.  P 41 

Roblado  river 215 

Rock    38 

Rock  decay 124 

Rock-fill  dams 33 

Rock  formations   114 

Routes    24,  70,  490 

Route  selected  by  commission  43,  45 

Runnels,  M.  L.  de 347 

Run-off    18,  19,  20,  293 

8 

Saabye,  O.  A.  F 52,  406,  410 

Sabalo  river,  infiow  to  lake 214,  216,  217 

Sabalos.  see  Savalos. 

San  Antonio  rainfall 280 

San  Carlos  embankmenls  27,  34,  103,  171 

San  Carlos  hills  105 

San  Carlos  river  8,  9,  54.  59,  101,  226,  228,  261 

evaporation  288 

hydrographic  station 226 

maximum  discharge   239 

rainfall   273 

sediment   299,  302 

temperature  and  humidity 324 

Sand    13,  153 

Sand  movement  off  Greytown  29,  61,  97,  480 

Sandstone   15,  126 

San  Francisco  embankments 27,  34,  35,  172 

hydrographic  station 244 

island,  rainfall 281 

rainfall   274 

river 8,  60,  123,  178,  243 

261,  394,  397,  409,  489 

Sanitary  and  climatic 12 

San  Jose  de  Costa  Rica  rainfall 262,  282 

San  Juan  del  Sur 14,  31.  32 

San  Juanillo  river  8.  30,  60,  180,  423.  424 

San  Juan  river   7.  58.  148,  217.  363 

bends  366 

canal  line 380 

canalization   26.  62 

capacity  of  channel  8,  9 

Castillo  station  223 

channel    378 

character  of  bed  60 

computed  velocity 10 

controlling  section 9 

cross-sections    8,  9 

curve  widening 377,  378 

cut-offs  3,  10,  63,  378 

dam  sites  167 


500 


INDEX 


San  Juan  river,  delta 29,  61,  97,  122,  151,  365 

depth  to  rock 63 

discharge   8.  260 

above  the  San  Carlos. 224,  226 

at  Ochoa  235 

at  Savalos 219 

of  tributaries  between  the 
Savalos  and  San  Carlos 

rivers   225.  239 

distances  7,  382 

drainage  basin 29 

drainage  system 148 

elevations    382 

erosion  of  channel 63,  69 

evaporation    59 

flood  plain 180,  237 

floods   68 

fluctuation  366 

lateral  drainage   8 

length   6,  7 

levels   381 

lower  division  151 

maximum  discharge 9,  59,  239 

maximum  velocity  8.  10,  69 

middle  division  149 

minimum  discharge 9 

Ochoa  station 232 

old  channel  104,  149,  171.  364 

physiographic  subdivisions 148 

political   division    368 

post-tertiary  time    140 

rainfall  in  basin  59 

rock  in  upper  river 45 

rocks    367 

Savalos  station  218 

sketches  of  variants  385 

slopes   7 

soundings  370 

statistics   7 

submerged  area 377 

survey 2.  51,  52.  363,  369 

409.  416.  423,  479 

tributaries   366 

upper  division   149 

velocities    8 

velocities  in  river  and  canal 10 

377,  383,  384 

volume  and  tributaries 59 

San  Miguelito  river  214 

San  Pablo 348 

San  Ubaldo  evaporation 286 

hydrographic  station    211 

Sapoa  river  106,  214,  216.  217 

Sapper,  Dr.  Carlos 136 

Sarapiqui  camp  415 


Sarapiqui  rainfall  275 

ridge    179,  394,  397,  489 

river    8,  54,  59,  101,  239,  254,  261,  410 

sediment 303 

Sardina  river    216 

Sault  Ste.  Marie  canal 35,  46.  66 

Savalos  hydrographic  station 9,  218 

temperature  and  humidity   319 

rainfall  271 

river  8,  222 

Schlecht,  W.  W....51.  213.  220.  243,  244,  246,  250,  251 

Scott,  A.  L 52,  348,  352 

Secretary  of  the  Navy 1 

Sections,  geologic  161 

Sediment  observations  299 

Sediment  trap   300 

Seismic  record  136 

Seymour,  G.  F 52,  93,  413.  415,  440 

Shaler,  John  F 4 

Sharks  in  Lake  Nicaragua 146 

Shelter   14 

Shepard  lagoon 98 

Sherman,  John,  Secretary  of  State xil 

Shunk,  William  F 41 

Shute.  H.  C.  C 52.  400 

Sillco  hills 61,  180,  490 

Sillco  railroad   39,  425 

Silico  swamps  425 

Silt  13,  153 

Sincapa  river   364 

Sites  for  low  dams 34 

Slopes  4,  10,  13,  15.  16,  153,  378.  399.  490 

Smart,  George  J 52.  374 

Smith,  Edwin  F 40 

Smith,  W.  A 51.  93,  254,  400 

Snyder,  L.  S 52,  406.  412 

Soft  rock 16,  129,  155 

Solentiname  islands   372 

Spanish  war  5,  39 

Speciflc  gravity 159 

Spence,  Harry  51,  93 

Spillways    21,  22,  23.  294,  353,  355,  376 

Squire,  E.  G 132,  137 

Stadia  work 369 

Steel    14 

Steiger.  George   159 

Stockton,  C.  H 52,  370.  374 

Stockton,  John    52,  489 

Stone  .15 

building    15.  117,  118.  124.  158.  165,  176 

harness 158,  160 

induration    160 

speciflc  gravity    159 

toughness  160 

Storage,  necessary  292 


INDEX 


501 


Stream  capture 106,  108,  142,  208 

Stream  measurement  197 

Stuart,  F.  L.,  Ass't  Eng'r 4,  9,  12,  52,  85,  370 

374,  378,  397,  423,  441,  463,  472,  473 

report  by  359 

Sucio  lagoon   '. 98 

Summit  Level    43,  68,  291.  297,  375 

cost  of  lowering 291,  298 

length  of  43 

Superintendent  of  Coast  Survey 5 

Surface  examinations  161 

Surveys,  completed  5 

extent  of  53 

method  of  conducting 351,  369,  374,  392 

394,  409.  423,  479 
obstacles  to 351 

T 

Table  of  quantities  36 

Talpetate  or  talpuja  127,  132,  163 

Tamborcito  creek  123,  408 

hill    29,  179 

lagoon  embankment  173 

point  embankment   172 

region   98 

ridge   397 

Tambor  Grande 397,  406,  415 

dam   27,  33,  52,  171,  405,  416 

hills  178 

survey    405,  411,  413,  415 

Taura  river  8,  60,  256,  479 

Taylor,  J.  C 52,  374 

Telcolostate  river 216 

Telpetate,  tepetate,  talpetate  or  talpuja.  .127,  132,  163 

Temperature    6,  11,  12,  304 

Tepenaguasapa  river 215,  216,  217 

Tertiary,  anterior  to  138 

early    138 

igneous  rocks  119 

middle  139 

post    140 

Thomas,  W.  D 52.  413.  415.  418,  479 

Three  dams  compared  with  one 29,  34,  80,  380 

Tierney,  Patrick    51,  93 

Tilley,  Commander  B.  F 5 

Timber  14,  867,  398.  417,  428 

Tipitapa,  evaporation   288 

hydrographic  station 208 

rainfall    267 

river    147,  209,  216.  217,  298 

Tiroli  river  214 

Tola  basin    350,  355 

hydrographic  station  198 

rainfall    264 

river   25,  142,  200 


Tola,  temperature  and  humidity 304 

Topography  54,  95.  370 

Toro  rapids 150,  183 

Torrington,  F.  R 51,  370,  440 

Tortuga  river  216 

Toughness  of  stone  160 

Transportation    417 

Trap  rock 15,  120,  158 

Trundle,  H.  H...51,  52,  85,  405,  411,  441,  471,  473,  489 

report  by  387 

Tufa   163 

Tuff  120 

Tule  river  214,  216,  217 


Unit  Prices 37,  42,  46,  70,  72,  84,  379,  425,  490 

Uplift  and  Erosion 139 


Valle  Menier  rainfall 280 

Valleys,  river  97 

Value  of  estimates 2,  84,  161,  296,  369,  379 

Vanderbilt  steamers 202,  212 

Vargas,  E.  T 52 

Vegetation   398,  425 

Velocities  in  river  and  canal 377,  383,  384 

Velocity  of  streams  197 

"  Victoria,"  lake  steamer    3,  348 

Volcanic  activity 132,  144 

Volcanic  conglomerates  157 

Volcanic  mountain  ranges  108 

Volcanic  plateaus  110 

Volcanic  rocks  119,  123 

Volcanic  sand  154 

Volcanic  sand  along  the  sea  coast 480 

Volcanic  sandstones 157 

W 

Wadleigh,  G.  R 51,  210,  235,  254 

Walker,  J.  W.  G..  Ass't  Eng'r 51,  52,  85 

410,  441,  472,  474 

report  by  343 

Walker,  Rear  Admiral  John  G.,  President  of 

Commission  xi,  xii,  1,  46 

Washington  headquarters 5 

Wasp's  nests 352 

Waste-ways   2,  63,  68,  355,  395,  426 

Water  power   14 

Water  supply 42,  291,  356 

Weathering    16,  124 

Webb,  H.  E 52,  413 

Western  divide 106 

Western  division   !  .2,  6,  7,  24.  51,  57,  343 

Wet  season 18