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VOLUME  XXXVIII.  NUMBER  559. 

New  Series.     Volume  XII.     Part  2. 

Entered  at  Stationers'  Hall.  Articles  : 


FEBRUARY,    1915. 

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CONTEXTS. 


Chapters  ik  Spectrim  Analysis.     I. 

By   \V.  Marshall   Watts.  D.Sc.  iS 

Correspondence 37 

Flora  Selborniensis ...     38 

Solar   Disturbances  during  December.  1914. 

By  Frank  C.  Dennett.     43 

The  .Amateur  in  Astronomy  (continued). 

By  \V.  F.  Dcnniit^.  F.R..A.S.     44 

The  Zoological  Society.  44 

The  Teeth  of  the  Wo.mbat  and  the  Beaver.    ...  47 
The  Face  of  the  Sky  for  March. 

By  A.  C.  D.  Crommelin.  B.A..  D.Sc.  F.R.A.S.  47 

Regeneration ...         ...  48 

Notes. — 

Astronoinv. 

By  A.  C.  D.  Crommelin.  B.A..  D.Sc.  F.R.A.S 


Notes  'continued) : — 

Botany.        By  Professor  F.  Cavers.  D.Sc.  F.L.S.  51 
Chemistry. 

.B.v  C.  Ainsworth  Mitchell.  B.A..  F.I.C.  52 

Geography By  A.  Scott.  M.A.,  B.Sc  53 

Geology.           By  G.  W.  Tyrrell.  A.R.C.Sc.  F.G.S.  53 

Meteorology.    By  William  Marriott,  F.R.  Met. Sac.  53 

Microscopy.       ...           By  J.  E.  Barnard.  F.R.M.S.  54 

Photography.     ...          ...          ...     By  Edgar  Senior.  55 

Physics.    By  J.  H.  Vincent.. M. A.,  D.Sc.  A.R.C.Sc.  56 

Radio-.\ctivity.                By  .Alexander  Fleck.  B.Sc.  57 

Zoology. 

By  Professor  J.  .Arthur  Thomson.  M.. A. .  LL.D.  58 

Reviews 59 

Notices 64 


51 

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Index  of  Spectra 

NEiV    SERIES. 

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Appendix  V  contains  .\ir,  .\ldebaranium.  Aluminium, 
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prosium, Erbium,  Europium,  Fluorine,  and  "Additions 
and  Corrections  to  Appendix  V,"    I2s.  6d. 


From  "  Xatiire."   December   11th.   1913  : — 

"  '  Watts'  Index  of  Spectra.' — Vet  another 
series  of  .\ppendices  to  this  most  valuable  com- 
pilation of  wave-length  data  has  been^commenced 
bv  the  publication  of  Appendix  V."        " 


Po<t   ^^v.•   /roni   the  AtitJior: 

Dr.    W.     MARSHALL    WATTS, 

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camera  vised  by  ardent  photographers  who  have  wished  to  secure  a 
photograph  of  a  iiniiiue  or  interesting  specimen." 

JOHN  BROWNING!;Ss;^S^x''fS^d^S?  LONDON. 


Estab.  17e.=. 


■  ■Optician,  72  New  Oxford  St. 

I  .  !.  Xo 


THE 


English  Mechanic 

WORLD  OF  SCIENCE 

Commences  with  Volume  C I 
its  Second  Century. 


For  fifty  years  it  has  steadily  and  continuously  broadened 
the  bounds  of  its  influence,  and  yearly  added  to  the  ranks 
of  its  thousands  of  voluntary  helpers.  We  ask  to-day,  not 
for  conscription,  but  for  universal  voluntary  service  in  the  task 
of  enlisting  the  young  in  the  service  of  science.  It  is  no  duty 
of  ours  to  disc\iss  whether  we  were  ready  as  a  nation  for  the 
srreat  struggle  in  which  the  Briti'^h  Empire  is  engaged  :  but 
it  is  no  secret  that,  after  a  generation  of  universal  elementary 
education,  the  niajoritv  of  our  countrymen  grow  into  man- 
hood and  womanhood  ill  equipped  for  the  industrial  struggle 
with  their  competitors  of  better-trained  nations,  and  content 
to  seek  recreation  in  vicarious  athletics  and  the  unedifying, 
hut  exciting,  "popular"  literature  of  the  time.  Of  hundreds 
of  thousands  of  these  it  is  the  bare  truth  to  say  the  fault 
is  not  theirs,  but  that  of  their  teachers.  If  youth  were  but 
led  jiid'ciou'-lv,  and  without  pedantry,  to  the  realisation 
of  the  plej-sures  of  science,  aptitude  and  inclination  would 
attract  yearly  increasing  thousan  Is  to  the  profitable  utiUsation 
thereof  in  manhood  One  proof  that  this  is  so  is  the  eagerness 
with  which  the  English  Mechanic  is  read  in  schools  where 
the  tencbers  have  familiarised  the  children  with  its  contents, 
\\'ill  more  teachers  make  The  English  Mechanic  and  World 
OF  Science  tbeir  school  book  ?  If  so,  thousands  of  men  and 
women  who  will  read  if^  pages  tifty  years  hence  will  gratefully 
remember  them.  ^^^^__^^^^^^^«^ 

A  Specimen  Copy  will  be  sent  free  to  any  address 

on  reciiiest. 

ENGLISH    MECHANIC, 

5.   EFFINGHAM   HOUSE, 
ARUNDEL   STREET.   STRAND.  LONDON,    W.C. 


Knowledge. 

With  which  is  incorporated  Hardwicke's  Science  Gossip,  and  the  Illustrated  Scientific  News. 

A    Monthly    Record   of  Science. 

Conducted  by  Wilfred  Mark  Webb,  F.L.S.,  and  E.  S.  Grew,  M.A. 


FEBRUARY,     1915. 


CHAPTERS    IN    SPECTRUM    ANALYSIS. 

By    W.    MARSHALL    WATTS,    D.Sc. 

L — Law  and  Order  in  Spectra. 
A.  Line  Spectra. 


"  First  the  flaming  red 
Sprang  vivid  forth  ;    the  tawny  orange  next  ; 
And  next  delicious  yellow,  by  whose  side 
Fell  the  kind  beams  of  all-refreshing  green  ; 
Then  the  pure  blue,  that  swells  autumnal  skies. 
Ethereal  played  ;   and  then,  of  sadder  hue. 
Emerged  the  deepened  indigo,  as  when 
The  heavy-skirted  evening  droops  with  frost ; 
While  the  last  gleamings  of  refracted  light 
Died  in  the  fainting  violet  away." 

"  Science  moves  but  slowly,  slowly,  creeping  on  from 
point  to  point." 

The  scientific  investigator  is  a  man  with  an  in- 
quisitive mind.  He  may  possess  the  aesthetic 
temperament  which  can  appreciate  to  its  fullest 
extent  the  beauty  of  any  phenomena  he  observes, 
but  he  is  never  satisfied  until  he  can  understand 
and  explain  the  cause  of  the  phenomenon  he  in- 
vestigates ;  and  he  is  only  completely  happy  when 
he  has  succeeded  in  reducing  the  matter  to  formulae. 
Others  may  be  satisfied  with  the  perception  of 
beauty,  and  may  regard  the  attempt  to  express 
the  phenomena  by  mathematical  formulae  as  a  sort 
of  profanation.  I  have  known  musicians  impatient 
of  all  attempts  to  explain  harmony  or  concord  or 
discord,  and  there  are  artists  capable  of  painting 
the  rainbow  with  the  colours  in  the  wrong  order! 
Can  there  be  anything  more  beautiful  than  a 
spectrum  (or,  at  first  sight,  more  uninteresting 
than  a  catalogue  of  the  wave-lengths  of  the  lines 
which  make  up  the  spectrum)  ?    Yet  I  venture  to 


think  that  there  is,  so  to  speak,  more  beauty  in 
the  law  and  order  revealed  by  a  patient  study  of  a 
dry  catalogue  of  wave-lengths  than  that  perceived 
by  the  mere  contemplation  of  the  harmoniously 
grouped  colours  of  the  spectrum  visible  to  the  eye. 

"  The  harmonious  spheres 
Make  music,  though  unheard  their  pealing 
By  mortal  ears." 

Even  in  the  early  days  of  spectrum  analysis  it 
was  felt  that  there  must  be  some  connection  between 
the  vibrations  to  which  the  bright  lines  of  a  glowing 
gas  are  due,  and  the  earlier  attempts  at  tracing 
this  connection  were  based  upon  analogy  with 
music.  In  following  up  such  an  analogy  we  must 
employ  numbers  of  vibrations  instead  of  wave- 
lengths. The  number  of  vibrations  per  second  of 
the  red  light  of  incandescent  hydrogen  is  obtained 
by  dividing  the  velocity  of  hght,  300,000  kilo- 
metres per  second,  by  the  wave-length,  which  is 
6563  ten  millionths  of  a  millimetre  for  the  red 
Hu  line.  This  gives  457-108  million  milHon  vibra- 
tions per  second.  To  avoid  these  unwieldy  numbers 
it  is  preferred  to  divide  the  wave-length  into  one 
centimetre,  or  10^  ten  millionths  of  a  millimetre,* 
so  that  we  obtain  the  number  of  oscillations  made 
while  light  is  travelling  one  centimetre.  This  is 
called  the  "  oscillation-frequency."  In  the  visible 
portion  of  the  spectrum,  X,  the  wave-length 
in  tenth-metres,  is  represented  by  four  figures 
before  the  decimal  point,  and  lO'/X,  or  lO^X"'   is 


*  One-ten  millionth  of  a  millimetre  is  called  one  "  tenth-metre." 


33 


34 


KNOWLEDGE. 


February,  1915. 


represented    by    five 
point.      For    example,    the 
hydrogen-vacuum  tube  are 
Wave- 
lens;th. 

Ha    6563-042 

H/i    4861-49 

H-y    4340-66 

Hd    4101-89 


figures    before 


the    decimal 


four    lines    seen    in    a 
given  thus  : — 
Oscillation- 
frequencv. 

15236-84 

20569-82 

23038-0 

24379-0 


Professor  Johnstone  Stoney,  guided  by  musical 
Table  7. 


Observ'ed. 

Calculated  from  the  formula 

(I.A.) 

O.F. -27419-805-  109679-22 

Ha 

6562  -793 

6562-793 

H^ 

4861-326 

4861-327 

Hy 

4340-467 

4340-466 

H5 

4101-738 

4101-738 

He 

3970-075 

3970-075 

Hi- 

3889-051 

3889-052 

analogy,  endeavoured  to  explain  the  rhythmical 
arrangement  of  lines  on  the  theory  that  they  were 
overtones  of  a  very  low  fundamental  vibration, 
since  Ha,  H^,  and  Ho  might  be  the  twentieth, 
twenty-seventh,  and  thirty-second  harmonics  of 
a  fundamental  vibration  of  oscillation-frequency 
761  -845.  But  there  was  no  place  for  H-y  in  this 
arrangement,  and  no  reason  why  these  harmonics 
only  should  be  observed ;  nor  does  the  theory  account 
for  the  extensive  series  of  lines  observed  in  stellar 
spectra  by  Sir  William  Huggins  and  others.  It  is 
now  generally  admitted  that  such  theories  will  not 
account  for  the  facts. 

The  first  striking  success  in  the  attempt  to  explain 
these  regularities  was  obtained  in  1885  by  Pro- 
fessor Balmer,  who  found  that  the  hydrogen  lines 
were  connected  in  a  simple  manner  with  the  suc- 
cession of  natural  numbers  from  3  onwards,  the 
wave-lengths  of  Ha,  H^,  Hy,  Ho,  and  so  on,  being 
f'  i'  If'  S'  ^^"^  so  on,  of  the  wave-length  3646-1 
of  a  "  head  "  in  the  violet,  to  which  the  lines  crowd 
continually  closer  and  closer.    Otherwise  expressed, 


X  =  3646-14 


m' 


where    m 


is   put   equal   to 
or,  if  we  use 


w  —  4 ' 
3,  4,  5,  and  so  on,  in  succession 
oscillation-frequencies,  O.F.  =  27418-75  (1  -  Altn^). 
We  may  obtain  an  interesting  representation  of  the 
law  which  holds  in  this  spectrum  by  measuring 
the  distance  of  the  lines  from  the  "  convergence- 
frequency  "  at  27418-75,  which  we  may  write  C.F. 

4C.F. 


We    have    C.F.  — O.F.  = 

V  =  — .  then  y^  =  .^  .^ 
■^        m  -^        4C.F. 


m' 


or,   if    we    put 


(C.F.  -  O.F.) ,  which  is  the 


equation  of  a  parabola. 

Figure  27  illustrates  this,  in  which  the  upper  part 
shows  the  series  of  hydrogen  lines  which  have  been 


observed,  and  the  lower  shows  the  parabolic  curve 
which  connects  the  stars,  plotted  with  a  scale  of 
1  jm  along  the  left  margin,  and  a  scale  of  oscillation- 
frequencies  along  the  bottom  of  the  diagram. 
Along  the  right-hand  margin  is  shown  a  scale  of 
1  jni^ ;  and,  when  the  lines  are  plotted  with  this 
and  the  bottom  scale,  it  is  seen  that  all  the  points 
lie  accurately  along  a  straight  line. 
The  formula  given  above,  namely, 
1 


r 

may  be  written 

.,2  ■ 


4C.F. 


1 


m^      109675 


(C.F. -O.F.) 


(C.F.-O.F.), 


or 


O.F.  =27418-75 - 


109675 


nr 


The  researches  of  Kayser  and  Runge,  of  Rydberg 
and  others,  have  shown  that  in  most  spectra, 
though  the  lines  may  appear  to  be  distributed  at 
random,  yet   in  very  many  cases   series  of    lines. 


Table 

8. 

Observed. 

Calculated. 

Vacuum- 

Chromosphere. 

O.F.  =27418-75 

109675 

Ames.* 

Dyson,  t 

Evershed  \ 

Mitchell.§ 

m- 

6563-042 

6563-045 

6563-07 

4861-49 

4861  -527 

4861-90 

4861-52 

4340-66 

4340-634 

4341-17 

4340-64 

;  4101-85 

4101-92 

4101-900 

4102-00 

4101-90 

3970-25 

3970-21 

3970-212 

3970-48 

3970-24 

;  3889-15 

3889-15 

3889-15 

3889-47 

3889-21 

1  3835-6 

3835-53 

3835-53 

3835-69 

3835-54 

'  3798-0 

3798-06 

3798-00 

3798-15 

3798-05 

3770-7 

3770-79 

3770-73 

3770-90 

3770-79 

3750-25 

3750-32 

3750-27 

3750-41 

3750-30 

:  3734-15 

3734-52 

3734-53 

3734-63 

3734-52 

3721-8 

3722-05 

3721-98 

3722-20 

3722-12 

3711-9 

371212 

3712-13 

3712-20 

3712-12 

3704-00 

3704-01 

3704-03 

3704-00 

3697-29 

3697-28 

3697-35 

3697-30 

3691-70 

3691-70 

3691-78 

3691-71 

3687-00 

3686-96 

3686-97 

3686-98 

3682-92 

3682-94 

3682-96 

3682-96 

3679-50 

3679-52 

3679-48 

3679-51 

3676-54 

3676-51 

3676-48 

3676-51 

3673-90 

3673-87 

3673-96 

3673-91 

3671-46 

3671-53 

3671-45 

3671-63 

3669-58 

3669-55 

3669-60 

3669-60 

3667-89 

3667-83 

3667-91 

3667-82 

3666-21 

3666-25 

3666-23 

3666-24 

3664-78 

3664-74 

3664-80 

3664-82 

3663-58 

3663-55 

3663-56 

3663-55 

3662-35 

3662-36 

3662-37 

3662-36 

3661-35 

3661-31 

3661-42 
3660-47 
3659-88 
3658-80 
3658-19 
3657-40 
3656-80 

3661-36 
3660-42 
3659-86 
3658-80 
3658-07 
3657-41 
3656-83 

*  Ames,  Phil.  Mag.,  1890,  XXX.  33. 
t  Dyson,  Phil.  Trans.,  1906,  CCVI,  403. 


+  Evershed,  Phil.  Trans.,  1903,  CCI,  457. 

§  Mitchell,  Astrophys.  Joiirn.,  1913,  XXXVHI,  407. 


February,  1915. 


KNOWLEDGE. 


35 


.\     li!  ONIS 


I 
77    0     I     V      ^        \  K 


IT  I    r 


1  '  E.  M4< 


a.  Lyr/E 


HHffT^iW  I 


6  n 

Figure  25. 


Heliu-tn     ■    Rl&EL 


bMiciwTn.  -Titanii/ 


a.  Cy&nt 


hrom  Spectrograms 


Figure  26. 
The  Spectrum  of  Hydrogen  as  observed  in  the  Stars. 


36 


KNOWLEDGE. 


February.  1915. 


^m/^     JO     9]V3^ 


February,  1915. 


KNOWLEDGE. 


37 


similar  to  the  hydrogen  series,  can  be  traced.  In 
each  series  the  Hnes  succeed  each  other  with  great 
regularity,  becoming  closer  together  and  diminish- 
ing in  intensity  as  we  pass  from  red  to  violet,  thus 
approaching  a  "  head  "  or  limit.  Several  series 
may  coexist  in  the  same  spectrum.  These  series 
may  be  represented  by  formulae.  It  appears 
probable  that  the  number  1 09675  is  the  same  for  all 
spectra  and  all  elements,  so  that  it  is  a  "  universal 
constant  "  of  Nature.     Rydberg's  general  formula  is 

O.F.  =  C.F.  - 1^5^,,  which  differs  from  the  simpler 

formula  for  hydrogen  only  by  having  another 
term,  fi. 

The  complexity  of  a  spectrum  is  found  to  depend 
in  some  way  upon  the  position  of  the  element 
furnishing  it  in  the  Periodic  Table  of  Mendelejeff, 
or,  in  other  words,  the  lower  the  atomic  weight  of 
an  element,  the  simpler  its  spectrum.  Thus 
hydrogen,  with  atomic  weight  1,  has  the  simplest 
of  all  spectra.  Probably  fi  is  not  really  zero,  but 
*  Curtis,  Proc.  Roy.  Soc,  1914,  XC,  605. 


has  some  very  small  value.  Curtis*  has  recently 
shown  that  the  wave-lengths  of  the  first  six  hydro- 
gen lines  are  given  with  extreme  accuracy  by  giving 
to  /J.  the  value  0-0000069,  as  shown  by  the  following 
comparison  (see  Table  7),  in  which  the  wave- 
lengths are  given  in  terms  of  the  International  Unit. 

The  series  of  hydrogen  lines  now  known  consists 
of  thirty-five  Unes  :  of  these  only  the  first  thirteen 
have  been  observed  as  bright  lines  in  the  vacuum 
tube ;  the  rest  occur  as  dark  lines  in  the  spectra 
of  stars,  as  seen  in  the  reproduction  of  Sir  William 
Huggins's  photographs  (see  Figures  25  and  26),  or 
as  bright  lines  in  the  spectrum  of  the  Sun's 
chromosphere.  The  latest  determinations  are 
brought   together   in   Table   8. 

The  series  of  stellar  lines  observed  by  Pickering 
in  f  Puppis  (see  "  Knowledge,"  1914,  Volume 
XXXVII,  page  59)  is  given  approximately  by  the 

formula  O.F.  =  27418-75 -1^^^^„.      But     it    is 

more  probable  that  these  lines  are  due  to  helium,  f 
t  Fowler,  Phi!.  Trans..  1914,  CCXIV,  256. 


CORRESPONDENCE. 


HIGH  TIDES   AT   FREMANTLE. 
To  the  Editors  of  "  Knowledge." 

Sirs, — The  following  information  about  the  Fremantle 
tides.  Western  Australia,  may  be  of  value  to  your  corre- 
spondents on  this  subject.  I  have  been  engaged  upon  an 
analysis  of  these  tides,  and  am  therefore  in  a  position  to 
give  (H)  the  semi-range  in  feet  and  (K)  the  phase-constant 
for  the  various  tides. 

In  Table  9  appear  the  H  and  K  of  those  com- 
ponents that  evidently  are  the  chief  controlling  factors 
of  the  Fremantle  tide.  It  shows  very  clearly  that  the 
Luni-solar  and  Lunar  declinational  are  the  two  main  ones 
to  be  considered. 


portion  of  the  Swan  River  extends  past  Perth,  about  fifteen 
miles  from  Fremantle,  and  beyond  that  the  river  is  of  \-ery 
small  extent,  and  there  is  no  current  to  speak  of  ;  in  fact, 
ten  miles  farther  on  it  dwindles  to  quite  a  small  stream. 
The  Darling  Range,  where  it  takes  its  source,  is  only  a 
comparatively  low  elevation,  and  consequently  there  is 
no  head  of  water.  As  to  ocean  currents,  there  is  certainly 
one  passing  along  the  coast  from  south  to  north,  but  its 
rate  is  only  of  small  account.  The  chief  cause  of  irregularity 
in  the  Fremantle  tides  is,  I  think,  to  be  looked  for  in  the 
prevailing  winds. 

This  peculiarity  can  very  probably  be  accounted  for  by 
the  disturbing  influences  of  the  wind  and  weather  on  the 
comparatively  small  range  of  tide  prevailing  at  Fremantle, 


Table  9. 


Title. 

Name. 

Period. 

Jlean  of  Years  1911-12.* 

H. 

K. 

O 
P 

Q 
:m., 

S, 

Luni-Solar  Declinational ... 
Lunar  Declinational 
Solar  Declinational 

{mp"c^"n°-^-^--' 

Mean  Lunar 

„     Solar              

Diurnal    ... 
Semi-diurnal 

Ft. 
0-431 
0-320 
0-130 

0-079 

0-112 
0-109 

0 

310 
319 
284 

325 

319 
318 

*  Figures  for  1908,  1909,  1910  analysed  by  Mr. 

H  K 

Ft. 

Ki  0-445  319 

O  -322  324 

P  -144  313 

Of  the  long-period  tides  the  Solar  Annual  is  probably  of 
most  importance,  but  the  values  for  different  years  for  these 
tides  do  not  agree  very  well,  and  therefore  I  have  not 
included  them. 

One  of  your  correspondents  suggests,  as  causes  of  irregu- 
larity, strong  river  flows  or  strong  ocean  currents.  In  this 
connection  I  would  point  out  that  the  estuary  or  salt-water 
which,  except  at  certain  short  periods  during  each  month, 
when  it  exceeds  two  feet  six  inches,  rarely  averages  more 
than  eighteen  inches  ;    thus,  should  a  strong  easterly  or 


Cooke  are  as  follows  (the  agreement  is  good) : — 

H  K 

Ft. 

Q  0-083  333 

M,  -116  325 

S/  -109  318 

nor'-easterly  wind  be  blowing,  the  theoretical  time  of  high 
water  is  almost  certain  to  be  delayed,  and  the  height  also 
diminished.  On  the  other  hand,  the  sou'-wester  or  sea 
breeze  banks  up  the  water  to  a  greater  or  less  degree, 
dependent  upon  its  intensity,  accelerating  the  time  of  high 
water,  augmenting  its  height  and  prolonging  its  duration. 
This  would  be  especially  noticeable  during  a  westerly 
blow,  and  the  exceptional  height  often  reached  by  the  tides 
during  the  winter  months  is  almost  solely  due  to  the  banking 
up  of  the  water  against  our  western  coast  Une  ;    although 


38 


KNOWLEDGE. 


February,  1915. 


in  this  connection  it  must  be  remembered  that  the  great 
tide-wave  which  travels  along  the  south  coast  ol  the 
continent  from  east  to  west  is  retarded  by  a  westerly 
wind,  and  its  height  necessarily  increased,  and  consequently 
there  occurs  an  additional  banking  up  of  the  water  of  the 
ocean  off  Cape  Leeuwin,  which  makes  its  effect  felt  to  a 
greater  or  less  extent  northwards. 

"  Thus,  when  the  Moon  is  in  Perigee,  the  tides  are 
invariably  higher  and  the  range  greater  than  in  Apogee. 
This  is  onlv  to  be  expected,  for  its  attractive  force  is  then 
at  a  maximum.  So  in  this  respect,  at  all  events,  the  Fre- 
mantle  tides  conform  to  the  generally  recognised  law. 
On  the  other  hand,  we  might  expect  to  find  some  regular 
sequence  of  change  existing  between  the  tides  and  the  phases 
of  the  Moon,  but  a  comparison  between  the  times  and  heights 
of  high  and  low  water  with  the  age  of  the  Moon  fails  to  dis- 
close any  existing  connection  ;  in  fact,  it  only  still  further 
serves  to  emphasise  the  complications  present  in  the  tide- 
governing  forces,  and  to  demonstrate  the  difficulties  likely 
to  be  met  with  in  an  attempt  to  accurately  explain  them. 
For  the  greatest  and  least  ranges  occur  both  at  the  change 
and  full  of  the  Moon  alike. 

"  It  should  be  noted  in  this  comparison  that  at  about 
the  time  of  first  quarter,  and  again  at  last  quarter,  the 
diurnal  tide,  namely,  one  high  and  one  low  during  the  day, 
is  almost  invariably  in  evidence.  It  also  may  be  taken  as 
a  general  rule  that  the  highest  tides  and  greatest  range 
occur  about  the  time  of  Moon's  first  quarter,  although  this 
sometimes  breaks  down.  At  the  time  of  full  or  new  Moon 
the  semi-diurnal  tides  often  make  their  appearance,  marked 
by  small  range  and  great  irregularity.  But  it  sometimes 
happens,  as  mentioned  above,  that  the  highest  tides  and 
the  greatest  range  take  place  at  these  times,  with  the  almost 
certain  prevalence  of  a  diurnal  tide. 

"  A  comparison,  however,   with  the  Moon's  position  in 


declination  shows  that,  when  the  Moon  is  on  the  Equator, 
the  least  range  occurs,  the  variation  in  water-level  being 
about  one  foot,  and  also  great  irregularity  in  the  times  of 
high  and  low  water  is  apparent.  Very  little  reliance  can 
be  placed  upon  the  tidal  predictions  at  this  period.  Often, 
for  quite  a  considerable  length  of  time,  the  water  remains 
unchanged  in  level.  The  semi-diurnal  tides,  namely, 
two  highs  and  two  lows  during  the  twenty-four  hours,  are 
also  in  evidence,  but  the  secondaries  are  sometimes  barely 
perceptible,  the  difference  between  the  heights  of  this 
inferior  high  and  low  water  being  only  a  few  inches. 

"  As  the  Moon  moves  north  or  south  of  the  Equator, 
the  range  gradually  increases,  and  the  tidal  curve  becomes 
regularly  diurnal  in  character.  More  dependence  also  may 
be  placed  upon  the  predicted  times  as  the  Moon's  distance 
from  the  Equator  increases. 

"  Contrary  to  what  might  be  expected,  the  highest  tide 
and  greatest  range  happen  when  the  Moon  is  at  its  farthest 
north  point,  and  not  at  its  greatest  south  declination,  when 
the  Moon  would  be  almost  directly  over  Fremantle,  and 
would  thus  be  in  a  position  to  exercise  the  maximum 
attractive  force  on  the  water. 

"  It  may  be  stated,  therefore,  with  some  degree  of  cer- 
tainty, that  the  Fremantle  tides  depend  to  a  large  extent 
upon  the  Moon's  declination,  and  from  its  position  the 
range  of  tide  may  be  gauged  fairly  accurately ;  but  the 
irregularity  in  the  occurrence  of  successive  highs  and  lows, 
although  most  marked  when  the  Moon  is  on  the  Equator, 
is  still  to  be  expected  when  the  Moon  attains  her  greatest 
north  or  south  dechnation." 


H. 

The  Observatory, 
Perth,  W.A. 


B.     CURLEWIS, 

Acting  Government  Astronomer, 
Western  Australia. 


FLORA    SELBORNIENSIS. 

February,  Second  Month  [Continued). 
22nd. — For  the  Primrose  the  Linnean  name  is  used,  which  still  stands  at  the  present  day.  In 
a  similar  way  Gilbert  White  first  wrote  the  name  of  the  Thrush,  by  which  we  now 
know  it,  but  afterwards  replaced  the  specific  name  by  a  phrase.  He  likewise  takes  out 
the  specific  name  of  the  Chaffinch,  and  corrects  the  name  of  the  Titmouse  from  ater  to 
major.    The  Skylark  is  now  Alauda  arvensis. 

March,  Third  Month. 
As  the  Spring  is  now  beginning  to  come  on,  the  number  of  entries  naturally  very  much  increases. 

3rd. — Torquilla  is  now  the  specific  name  of  the  Wryneck.  The  Wood  Laurel  is  Daphne  laiireola.  The 
Black  Hellebore  is  Hellehorus  foetidns.  The  Long-tailed  Titmouse  is  now  Acredula. 
Lady-cows  are  presumably  Lady-birds. 

4th. — Chickweed  Speedwell  is  Veronica  agrestis. 

5th. — The  Common  Chickweed  [Stellaria  media).  This  plant,  with  the  Common  Groundsel  and  the 
Veronica  just  mentioned,  are  among  the  plants  which  may  be  found  in  flower  during  every 
month  in  the  year.  The  Missel  Thrush  is  Turdus  viscivorus.  The  Peziza  is  possibly 
P.  aurantia. 

6th. — The  Red  Dead  Nettle  is  Laniium  purpnreuni.  The  Common  Wren  is  Anorthuria  parvitla.  The 
Clothes  Moth  is  Tinea  pellionclla.  The  Yellow  Hammer  is  now  Emheriza  citronella. 
Gctim  nrhaniim  is  the  Common  Avens  ;  Wild  Cicely,  Anihriscus  sylvestris  ;  Herb  Gerard, 
Aegopodium  podagraria  ;  Fool's  Parsley,  ActJnisa  cynapium  ;  and  Goose  Grass,  Galium 
aparine. 

7th. — We  now  call  the  Wood  Lark  Lullttla,  the  Rook  Trypanocorax  frugilegus,  and  the  Jackdaw 
Coloeus  monedula. 

8th. — The  first-mentioned  Butterfly  is  the  Brimstone  [Gonepterix  rhamni),  and  the  others  are  pre- 
sumably small  Tortoise-shells  [Vanessa  urtica).  We  know  the  Blackbird  now  as  Merula 
merula). 

9th. — The  Hedge  Sparrow  is  Accentor  modularis.  Dog's  Mercury  we  call  Mercurialis  percnnis.  The 
Wood  Strawberry  is  Fragaria  vesca.  The  Ringdove  is  Columba  palumbus.  There 
is  an  interesting  observation  with  regard  to  the  Field  Cricket  [Grylliis  campestris) . 

10th. — Wormwood  is  now  Artemisia  absinthium. 


February,  1915. 


KNOWLEDGE. 


39 


Si. 


/£t^^^^  /t^^i^  ALAx^'it^-e^  /Mj  cJaJ^6A£j.^/^-6yi 

•^zioL^  aaMti  Ic^^  <rJUt.^  ^^^^»  ^cluj>Ll  thic^£ui^_ 

J^fij//- ^^  i^e^Ju^^  S^/&^  a^^^T^uO  g^/^l^j^  ^-t^e^t-. 

:/jufW^, ._- 


%)  '^O^^. 


^^AZ-A-JtJ 


'°  KNOWLEDGE.  P,3,„,,,_  ,,,,_ 


xf^r^  A->»-^. /•>■■>  ^    }^^^f^,n  ^fffffffff^  f^A^^/^^_  J/'^^,./j^^ 


(/tc  /<?^^?*  ^e^-t^  -/-^€L>,    a^fi/^iUA^^Jt,,  ^rLr&Af, 
<uHit,/>t/r/L  a^  /^^fct  ^UcLf  ^LJi!^^^  £^^ejy  i^^^: 

^.    JW  j£j£^/L£Mt^^    £z,M.i//.AL  t)~il^^JL^^   ^-IL&ttdJL ,  /£f^^>^^f^: 


February,  1915.  KNOWLEDGE. 


(fit  ^-iteU  /r/y&^  /h^jCLcA ,  kJtuc^  ^^s^^LC£L^  ^/i>€eL. 

J/e^  ^B^^xS^^  '^^hJ-mQ^  &-tit^X&}€Q,  eLA^e&tOL^yf, 
i^^i/^  cLa^'A^m^^   SumIiLal  (HtAjL^K.  AOfiLM,,  MJttA^^^t^chi . 

^2^A/a£^    &^  a^titxfjL'A^-^ ^    ^tJLJ^UU^  IHUMJU^^  ^/ifiO^ 


yfa^iHj]  yya£^,  /&t-e,>€yhf. 


''  KNOWLEDGE.  Februarv.  1915. 


/^UttAS>.    ^fa^  ft/^^A^.^.^/A    ^^Jf!^^'    ^' 


SOLAR    DISTURBANCES    DURING    DECEMBER,    1Q14 


By    FRANK    C.    DENNETT. 


NoT\%aTHSTANDixG  the  poor  meteorological  conditions  which 
prevailed  during  the  month,  only  three  days  (December  6th, 
11th,  and  28th)  passed  on  which  no  telescopic  examination 
was  made,  and  the  Sun  appears  never  to  have  been  free 
from  spot  disturbance.  The  longitude  of  the  central 
meridian  was  139'  28'  at  noon  on  December  1st. 

Nos.  43  and  44  of  the  No^^embe^  list  were  visible  until 
December  9th  and  10th  respectively,  and  therefore  reappear 
upon  the  present  chart. 

No.  43a. — A  group  of  pores,  which  broke  out  on 
December  2nd  in  front  of  No.  43,  and  continued  until  the 


on  the  21st  and  22nd,  and  one  was  situated  a  little  to  its 
south-west  on  the  23rd.    The  spot  was  last  seen  on  the  24th. 

A  pore,  not  measured,  but  estimated  to  be  in  the  position 
shown  by  a  tiny  cross,  near  longitude  134°,  S.  latitude  22°, 
was  only  visible  on  the  24th. 

No.  4S.-^-A  faculic  disturbance  was  seen  coming  round  the 
south-eastern  limb  on  December  24th,  and  on  the  25th  was 
found  to  be  connected  with  a  spot  nine  thousand  miles  in 
diameter,  which  was  last  seen  by  the  writer  on  January-  2nd. 

No.  49. — Two  pores,  only  observed  on  December  31st, 
separated  by  some  fiftv  thousand  miles. 


DAY    OF    DECEMBER,     1914. 


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5th.      Its   greatest   length,    on   the   3rd,    was   seventy-two 
thousand  miles. 

No.  45. — A  group  first  seen  as  two  considerable  spots 
just  round  the  limb  on  the  3rd.  The  eastern  spot  was  the 
largest,  with  three  or  four  umbrae.  Some  pores  helped  to 
make  up  the  group  on  the  8th.  The  length  of  the  group  was 
sixty-four  thousand  miles,  and  the  greatest  diameter 
of  the  spot  eleven  thousand  miles.  It  was  last  seen  on  the 
14th,  when  it  appeared  as  a  group  of  five  pores  in  a  facuUc 
disturbance. 

No.  46. — A  fine  group,  which  was  found  to  have  broken 
out  on  the  12th,  consisted  of  two  considerable  spots  about 
ten  thousand  miles  in  diameter,  with  some  pores  between 
them,  fifty-six  thousand  miles  in  length.  It  was  last  seen 
near  the  hmb  on  the  19th. 

No.  47. — A  spot  ten  thousand  miles  in  diameter,  first  seen 
on  the  18th  a  little  within  the  limb.    Two  pores  followed  it 


Faculic  disturbances  were  near  the  north-western  limb 
on  December  1st  (215°,  19°  N.),  5th  (160°,  16°  N.),  14th, 
24th  (274°,  19°  N.),  26th,  27th  (216°,  20°  N.,  and  204°, 
18°  N.),  and  29th  ;  north-east  on  December  1st  (75°, 
24°  N.),  16th,  27th  (86°,  13°  N.),  and  31st;  south-west 
on  December  5th,  16th  (21°,  25°  S.),  20th  (320°,  15°  S.), 
and  29th  ;  south-east  on  December  8th  (in  which  No.  46 
afterwards  developed),  23rd,  27th  (south  of  No.  48,  and 
96°,  27°  S.),  and  29th  (52°,  14°  S.). 

Our  chart  is  constructed  from  the  joint  observations  of 
Messrs.  John  McHarg,  A.  A.  Buss,  and  the  writer. 

A  second  chart  is  also  appended,  showng  the  distribution 
of  the  whole  of  the  spot  disturbances  of  the  past  year.  As 
compared  with  pre\-ious  year-charts,  it  will  be  noticed  that 
the  spots,  as  a  whole,  are  much  farther  from  the  Equator, 
are  more  numerous  than  in  the  three  previous  years,  and 
are  more  evenly  distributed. 


DISTRIBUTION    OF    SPOT    DISTURBANCES    DURING    1914. 


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B  43 


THE    AMATEUR    IN    ASTRONOMY. 


By    W.    F.    DENNING,    F.R.A.S. 
{Continued  from  page   11.) 


In  cases  where  affluent  amateurs  have  not  per- 
sonally undertaken  researches,  they  have  provided 
the  opportunity  for  professional  men,  and  America 
furnishes  some  prominent  examples,  among  which 
we  may  instance  the  great  observatories  of  Yerkes 
and  Lick. 

Of  course,  there  are  certain  investigations  which 
are  far  more  fittingly  conducted  at  well-equipped 
observatories.  The  determination  of  star  positions 
and  a  great  universal  work  like  that  of  the  astro- 
graphic  catalogue  are  far  beyond  the  capacities 
of  ordinary  amateur  effort. 

There  is  an  idea  that  all  the  objects  discoverable 
by  small  telescopes  are  now  known,  and  that  the 
great  instruments  recently  erected  must  be  left 
to  grapple  with  the  miniature  orbs  remaining 
unknown.  This  is  only  partly  true.  The  brighter 
minor  planets  have  been  found,  the  more  prominent 
double  stars,  variable  stars,  the  brighter  nebulae, 
have  all  been  detected  and  catalogued.  But  in 
regard  to  certain  other  objects  of  an  inconstant 
character  the  case  is  entirely  different.  I  refer  to 
solar  phenomena,  to  new  stars,  to  meteors  and 
aurorae.  There  are  constantly  recurring  supplies 
of  these,  easily  observable,  and  often  awaiting 
detection  by  the  acute  and  vigilant  observer,  be 
he  amateur  or  professional. 

On  walking  out  into  my  garden  a  few  nights  ago, 
to  do  a  little  observing  work  on  a  beautifully  starlit 
sky,  I  hesitated  a  moment  in  contemplation  of  the 
vast  conclave  above  ;  and  I  could  not  help  thinking 
what  a  vast  amount  of  useful  observation  there 
remained  still  to  be  done  by  systematic  effort. 
Ordinary  amateurs,  with  good  telescopes  and  prac- 
tised eyes,  might  accomplish  it.  Double  stars 
might  be  measured  or  new  ones  searched  for, 
Mars  and  Saturn  examined  and  drawings  made, 
sweeps  made  for  new  nebulae  or  new  comets, 
the  position  of  visible  comets  determined  ;  without 
telescopic  aid  the  light  of  variable  stars  might  be 
estimated,  new  variables  looked  for,  the  heavens 
scrutinised  for  new  stars,  a  watch  maintained  for 
meteors,  and  their  paths  recorded.  These  form  a 
few  items  of  the  work  suggested  by  the  inviting 
firmament  :    it  has  been  inadequately   performed 


in  the  past ;  let  it  be  more  thoroughly  effected  in  the 
future.  Let  amateurs  realise  that  their  role  is 
still  a  most  important  one,  and  that  splendid 
work  ever  awaits  able  and  well-directed  effort. 

They  should  certainly  not  be  discouraged  by  the 
supposition  that  they  are  now  too  heavily  handi- 
capped to  collect  any  valuable  contributions  to  the 
science. 

I  have  often  thought  that  there  is  not  a  wide 
difference  between  the  amateur  and  the  professional. 
In  some  cases  the  distinction  is  certainly  a  very 
trifling  one.  In  one  sense  assuredly,  men  like 
J.  F.  W.  Herschel,  R.  A.  Proctor,  W.  R.  Dawes,  and 
C.  Flammarion  can  hardly  be  regarded  as  merely 
amateur  astronomers,  but  it  is  obvious  that  in  every 
case  the  amateur  studies  the  stars  out  of  pure  love 
for  the  subject.  He  admires  the  wonderful  pictures 
the  heavens  afford,  and  marvels  at  the  mysteries 
involved.  There  is  a  sublimity  and  infinity  about 
astronomy  which  attract  the  intellectual  mind 
and  induce  a  feeling  of  reverence  and  awe.  The 
peer  and  the  plebeian  alike  are  tempted  to  "  lift 
up  their  eyes  on  high,"  for  there  is  often  found 
identity  of  feeling  amid  wide  differences  in  social 
status  in  the  great  brotherhood  of  humanity. 
With  regard  to  the  professional,  he  ostensibly  devotes 
himself  to  the  study,  not  exactly  as  a  way  to  wealth, 
but  as  a  means  of  earning  a  livelihood.  In  very 
many  cases,  however,  this  is  not  all.  Many  pro- 
fessionals work  at  astronomy  con  amove.  They  have 
selected  it  because  they  have  a  deep  regard  for  it. 
There  must  be  really  very  few  professional  astro- 
nomers but  who  feel  an  intense  interest  in  their 
subject,  and  whose  labours  are  prompted  by 
inclination.  Abundant  evidence  of  this  has  been 
afforded  by  them  in  recent  years,  for  they  have 
performed  heavy  work  of  honorary  character 
quite  outside  their  official  duties.  For  instance, 
the  British  Astronomical  Association,  which  is 
understood  to  provide  encouragement  for  and  useful 
cooperation  amongst  tyros  and  amateurs,  has  been 
assisted  in  most  material  degree  by  professional 
men  who,  after  their  heavy  routine  work,  have  freely 
devoted  much  time  and  attention  to  the  assistance 
of  mere  beginners  in  the  science. 


THE    ZOOLOGICAL    SOCIETY. 


The  registered  additions  to  tlie  Zoological  Society's 
Menagerie  during  tlie  month  of  December  were  fifty-two  in 
number.  Of  these  twenty-seven  were  acquired  by  presentation, 
eighteen  were  received  on  deposit,  three  in  exchange,  and  four 
were  born  in  the  Gardens.     The  following,  which  are  new  to 


the  Collection,  may  be  specially  mentioned :  A  Peter's 
Dwarf-Mongoose  (Hclogalc  undulata),  from  Wangi,  Tana- 
land,  E.  Africa,  deposited;  and  a  Golden-eared  Honey-eater 
iPtilotis  cltrysotis),  from  New  Guinea,  presented  by  Alfred 
Ezra,  F.Z.S. 


44 


February.  1915. 


KNOWLEDGE. 


45 


From  a  pho:os*aph  hy  I  <V',' 

Figure  28.     Mr.s.   Fiammetta  Wilson. 


/•■-.;;/  a  photngraph  hy  J     K instil  Sr  Sitiis. 

Figure  30.     The  Rev.  T.  E.  R.  Phillips,  M..\..  F.R..-\.S. 


/■rout  a  p/uitti^'a/'  : 


Figure  29.     WiUiam   Lassell. 


Figure  31.     G.  F.  Chambers,  J. P.,  F.R.A.S. 


46 


KNOWLEDGE. 


February,  1915. 


^ 


..-.i*' 


Figure  32. 

The  right  half  of  the  lower  jaw  of  a  Beaver,  showing  the  molar  teeth  standing 
high  oat  of  their  sockets,  which  are  above  that  of  the  incisor. 


# 


Figure  3i. 
The  left  half  of  the  lower  jaw  of  a  Beaver  for  comparison  with  Figure  34. 


I    1..1  Kt     j4. 

The  left  half  of  the  lower  jaw  ot  a  Wombat,  showing  the  molar  teeth  sunk  very  deeph-  in  their 
sockets,  which  curve,  while  the  first  actually  runs  under  that  of  the  incisor. 


THE  TEETH  OF  THE  WOMBAT  AND  THE  BEAVER. 


It  is  everyday  knowledge  to  naturalists  that,  among  the 
marsupials  of  Australia,  we  have  types  which  correspond 
wth  the  various  higher  orders  of  old-world  mammals,  and 
present  features  analogous  to  theirs,  owing  to  their  getting 
their  living  in  the  same  of  several  ways.  For  instance,  the 
Tasmanian  wolf  is  carnivorous,  the  kangaroos  are  herbi- 
vorous, and  the  wombat  gnaws  like  a  rodent.  The  matter 
which  concerns  us  here  is  connected  with  the  teeth  of  the 
last-mentioned  animal.  In  Figures  32  to  34  the  lower  jaw 
of  a  wombat  is  compared  with  that  of  a  true  rodent,  the 
beaver.  The  lower  incisor  of  the  latter  is  exceptionally 
large,  but  the  corresponding  tooth  in  the  wombat  is  also 
very  well  developed  (see  Figure  34).  It  will  be  seen  that  it 
is  necessary  to  find  room  for  the  large  incisors  in  both  cases. 
In  the  beaver,  as  shown  in  Figures  32  and  33,  the  molar 
teeth,  which  are  the  only  ones  developed  in  addition  to  the 


incisors,  stand  high  out  of  the  jaw,  and  their  sockets  are 
above  that  of  the  great  incisor.  In  the  wombat,  in  the 
anterior  part  of  the  jaw  at  any  rate,  there  is  just  the  same 
need  for  accommodating  the  incisor  socket;  but  it  wll 
be  seen  that  the  surfaces  of  the  molar  teeth  in  this  animal 
project  but  little  above  the  jaw,  and  it  is  by  the  curving 
of  the  molar  teeth  that  the  difficulty  has  been  got  over, 
the  sockets  ending  below  the  level  of  the  incisor,  and  in  the 
case  of  the  first  grinding  tooth  coming  directly  underneath 
it.  The  interest  lies  in  the  fact  that  the  same  necessity  has 
been  met  in  two  very  different  ways  in  a  rodent  and  in 
a  marsupial.  The  specimens  from  which  Figures  32  and 
34  were  taken  are  exhibited  at  the  Eton  College  Museum, 
to  which  Sir  Edmund  Loder  kindly  presented  the  beaver 
jaw. 

W.    M.    W. 


THE    FACE    OF    THE    SKY     FOR    MARCH. 


By    A.    C.    D.    CROMMELIN,    B.A.,    D.Sc,    F.R.A.S. 

Table  10. 


Date. 

Sun. 
R.A.      Dec. 

Moon. 
R.A.          Dec. 

Mercury. 
R.A.         Dec. 

Venus. 
R.A.      Dec. 

Saturn. 
R.A.         Dec. 

Neptune. 
R.A.      Dec. 

Greenwich 

Noon. 

Mar.  3 

h.  m.           0 
2249*3    S.   7*5 
23    7-9          5-6 
23  26"3           3  6 
23  44*7    S.    1*7 

0    2  "9   N.  0*3 

0  2I"I     N.    2*3 

h.   m.           0 

II   21*2      N.     1*9 

15  56*7  S.  25-8 

20  56 '6  S.  18*7 

0  491   >J-  9'5 

4  51-8  N.27*5 
9  18*7  N.i6*5 

b.    m.            0 

21    42*7    S.  ll'O 
21  40'5         12*4 

21  48*1        i2"g 

22  2'3        12*6 

22    22*5            11*6 

22  45'5  S.  10*0 

h.  m.            0 

19  48-4    S.i9'3 

20  11 '9        i8"6 
=0  35*5         17*6 

20  sS-g        i6's 

21  22*3        15*1 
21  45-4    S.i3*6 

h.     m.            0 
5   40*0     N.22-4 
5  4o'3          22*4 

5    40-8                 22*5 

5  41 '5           22'5 
5  42-3           22;5 
5  43  4     N.22  5 

h.   m.           0 
8  0-2    N.ao*2 
7  59*8         20*2 
7  59 '5          20 '2 
7  59-2           20'3 
7  59*0          20-3 
7  58*8    N.20-3 

,,    27 

T.\BLE    11. 


Date. 

Greenwich  Noon. 

Midnight 
Moon. 

P 

Sun. 
PEL 

0                        00 

—  2I'8                        —7*1                     21*0 

23-0                   7*3            315-1 
240                   7-2            2492 
24-8                     7'i              183*3 
25-5                     7'0             117*4 

—  26"q                 — 6'8                51*5 

+22*1 
+  9*4 
-i6'4 

—  21*5 

-  4-8 
+  i7'7 

P  is  the  position  angle  of  the  North  end  of  the  body's  axis 
measured  eastward  from  the  North  Point  of  the  disc.  B,  L 
are  the  heUo-(planeto-)graphical  latitude  and  longitude  of  the 

centre  of  the  disc. 
For   the   future   the   data  for  the  Moon   and  Planets  in  the 
Second  Table  will  be  given  for  Greenwich  Midnight,  i.e.,  the 

Midnight  at  the  end  of  the  given  day. 

The  letters  m,  e  stand  for  morning,  evening.      The  day  is 

taken  as  beginning  at  midnight. 

The  Sun  is  moving  Northwards  at  its  maximum  rate, 
crossing  the  Equator  21''  4'^  SI""  e.  Its  semi  -  diameter 
diminishes  from  16'  10"  to  15'  2".  Sunrise  changes  from 
6"  50"  to  5"  42" ;  sunset  from  5"  36"  to  6"  28"°. 

Penumbral  Eclipse  of  Moon.  —  There  vi-ill  be  a 
Penumbral  Eclipse  of  the  Moon  on  March   1st  about  7*"  e. 


A   slight    smokiness    will   be    discernible   on   the    Northern 
portion  of  the  disc. 

Mercury  is  a  morning  star  in  W.  elongation,  27°  43 
W.  of  Sun  on  20th.  Semi-diameter  diminishes  from  5"  to  3". 
Illumination  increases  from  I  to  5. 

Venus  is  a  morning  star.  Illumination  increases  from 
3  to  iV-     Semi-diameter  diminishes  from  10"  to  8". 

The  Moon.— Full  l"  6"  33"  e.  Last  quarter  8''  O"  28"  e. 
New  15*  7"  42"  e.  First  quarter  23^  lO"  48"  e.  Full 
31*  5"  38°  m.  Perigee  5"  3'"  m.  Apogee  ai*  l"-  m, 
semi  -  diameter  16'  19",  14'  46"  respectively.  Maximum 
hbrations  7*  7"  N.,  12*  5°  W.,  20*  7°  S.,  27*  7°  E.  The 
letters  indicate  the  region  of  the  Moon's  limb  brought 
into  view  by  libration.  E.,  W.  are  with  reference  to  our 
sky,  not  as  they  would  appear  to  an  observer  on  the  Moon 
(see  Table  12). 

Mars  is  invisible,  having  been  in  conjunction  with  the  Sun 
on  Dec.  24tb. 

Jupiter  was  in  conjunction  with  the  Sun  on  Feb.  24th, 
and  is  therefore  practically  invisible  this  month. 

Saturn  is  between  Taurus  and  Gemini.  In  perihelion 
Feb.  21st.  Stationary  Feb.  26th.  In  quadrature  Mar.  17th. 
Polar  semi-diameter  9".  Major  axis  of  ring  42",  minor  19". 
Angle  P-5°-7. 


47 


48 


KNOWLEDGE. 

Table  12.     Occultations  of  Stars  by  the  Moon  visible  at  Greenwich. 


February,  1915. 


Star's  Name. 

Magnitude. 

Disappearance. 

Reappearance. 

Date. 

Time. 

Angle  from 
N.  to  E. 

Time. 

Angle  from 
N.  to  E. 

1915. 

h.     m. 

0 

h.    m. 

jj 

Mar.   4 

75  Virginis            

57 

— 

— 

10    17  e 

237 

>'     5 

WZC  871 

7-0 

— 

— 

I     55  « 

345 

,,     8 

BAG  5603 

60 

3    3S  '" 

140 

4    37  '" 

245 

,,   10 

WZC  1243            

7-4 

— 

5    15 '« 

229 

„   24 

39  Geminorum 

6-1 

5     Of 

S5 

6    20  1; 

296 

„   24 

40  Geminorum 

6-3 

5    29  c 

116 

6    49  « 

267 

.,   25 

52  Geminorum      ...          

60 

I    46  m 

loS 

2    ^8« 

284 

„   25 

\VZC49S 

6-9 

I     56  '« 

162 

— 

— 

„  26 

fi^  Cancri 

5-4 

2      5  m 

■73 

2    30  m 

230 

„   26 

BAG  2991             

6-1 

8      Se 

106 

9     22  « 

312 

,,   27 

WZC  618 

71 

3      0  m 

177 

— 

— 

,,   27 

II  Leonis  ...          

6-6 

5     23  e 

86 

6    24  e 

327 

,,    29 

76  Leonis 

60 

5    36  « 

151 

6    26  e 

269 

„    30 

BAC4119            

6-6 

7    39  e 

153 

8    33  « 

275 

From  New  Moon  to  Full  disappearances  occur  at  the  Dark  Limb,  from  Full  to  New  reappearances. 


Eastern  elongations  of  Tethys  (every  4th  given)  S**  y*"  -7  m, 
10^  S^-g?,  ISMO^-a  m,  25*'  ll''-5  e;  of  Dione  (every  3rd 
given)  S-"  10'^  -1  m,  le*"  3""  -3  e,  24"*  S''-4  e  ;  of  Rhea  (every 
2nd  given)  T^  11''  -1  iit,  le''  Noon,  25^  l^-O  e. 

For  Titan  and  Japetus  E.,  W.  stand  for  East  and  West 
elongations,  I.  for  Inferior  (North)  conjunction,  S.  for  Superior 
(South)  conjunction.  Titan  4'*  e'' -8  m  S.,  S"*  9^ -1  m  E., 
12''  Qi^  -1  m  I.,  le'i  6*'  -3  m  W.,  20<'  6^  -0  m  S.,  24^  8'' -5  m 
E.,  28''  8''-5  m  I.;  Japetus  1''  2^  m  W.,  20''  1^  m  S. 

Uranus  is  invisible.  In  conjunction  with  Sun  on  February 
1st. 

Neptune  was  in  opposition  January  20th,  diameter  2". 

Double  Stars  and  Clusters. — The  tables  of  these, 
given  three  years  ago,  are  again  available,  and  readers  are 
referred  to  the  corresponding  tnonth  of  three  years  ago. 


Variable  Stars. — Stars  reaching  their  maxima  in  or  near 
March,  1915,  are  included.  The  lists  in  recent  months  may 
also  be  consulted. 

Meteor  Showers  (from  Mr.  Denning's  List) : — 


Date. 

Radiant. 

Remarks. 

R.A.      1      Dec. 

Mar.  1-4 

„      1-14      ... 

„      18         ... 

„      24 

„      27 
Mar.— May    ... 

166       +         4 
17s       +       10 
316       +       76 
161       +       58 
229       +       32 
263       +       62 

Slow,  bright. 
Slow. 

Slow,  bright. 
Swift. 

Swift,  small. 
Rather  swift. 

Table  13.    Long-period   Variable   Stars. 


Star. 

Right  Ascension. 

Declination. 

Magnitudes. 

Period. 

Date  of  Maximum. 

U  Persei          

W  Andromedae         

T  Camelopardi           

R  Aurigae       

R  Ursae  Maj.             

T  Ursae  Maj 

h.    m.      s. 

1  53     57 

2  12     II 

4  31      4S 

5  10    25 
10    38    42 
12    32    33 

+54     24 
+43     55 
+65     59 
+53     30 
+  69     13 
+  59     57 

70  to  10- 9 
7-0  to  13-8 
7-0  10  13-5 
6-5  to  13-3 
5-9  to  13-1 
5-5  to  I2'7 

d. 
317 
395 
370 

448 
299 
257 

1915 — Feb.   23 
,,       Feb.      9 
,,       Apr.    19 
,,       Apr.     4 
„       Feb.   27 
Jan.   28 

Night  Minima  of  Algol  I''  7"  -26,  4"  4"  -Oc,  Id"  3"  •4m,  19"  O''  -1  m,  21''  8"  ■ 
Principal  Minima  of  (3  Lyrae  March  l"  b^e,  14"  A^e,  27"  3""  c. 


9  e,  24"  5" -7  e.     Period  2"  20'"  48'° -9. 
Period  12"  21"  47"-5. 


REGENERATION. 


The  regeneration  of  "  arms  "  in  starfish,  claws  in  lobsters, 
and  tails  in  lizards  exemplifies  the  replacement  of  lost 
parts  in  animals  ;  and,  although  we  cannot  get  a  new  lizard 
from  an  old  tail,  or  a  new  lobster  from  a  discarded  claw,  yet 
it  is  possible  to  grow  a  new  starfish  from  a  detached  arm. 
In  the  vegetable  kingdom  this  kind  of  regeneration  is  more 
common,  and  is  put  to  practical  uses.  The  making  of 
a  cutting  may  not  seem  so  striking  as  the  growing  of 
a  new  starfish,  for  roots  only  have  to  be  formed  (see 
Figure  40),  and  this  underground  ;    but  many  leaves  can 


produce,  not  one  young  plant,  but  quite  a  number.  This 
is  the  case  in  Bryophvllum,  and  in  Figures  35  and  36  a  leaf 
is  shown  which  has  been  lying  on  the  moist  ground  for  a 
little  time.  The  edges  of  it  are  bounded  by  quite  a  clump 
of  young  plants.  Figures  36  to  39  show  other  leaves, 
which  will  reproduce  the  whole  plant,  and  the  begonia  is 
commonly  propagated  by  gardeners  in  this  way.  Figures 
40  to  49  also  bear  on  this  question,  and  it  is  possible  to 


obtain  a  geranium  from  a  leaf-stalk. 


W.  M.  W. 


February,  1915. 


KNOWLEDGE. 


49 


Figure  35.     Seen  from  abo\e.  Figure  36.     Side  view. 

Two  Views  of  a  Leaf  of  Bryophyllum.  showing  the  young  plants  which  it  produces  when  broken  off  and  laid  on  the  ground. 


Figure  37. 

A   Saintpaulia   Leaf  with   roots  springing   from   the 
petiole. 


Figure  38. 

Leaves  of    Tolnicia  Menziesii  sending  out  buds 
where  the  stalk  joins  the  blade. 


Figure  39. 
A  Begonia  Leaf  producing  new  plants. 


Figure  40. 

Pieces  of  the  thick  stem  of  an  Aroid  \Dicffcnbachia 
Batisei)    used    as    cuttings,   and    sending    out   roots 
and   shoots. 


50 


KNOWLEDGE. 


February,   1915. 


Figure  43. 


FiGURK   41.       .\    Leaf 

of  Peperomia  which  has 

sent  out  roots  from  its 

stalk. 


Figure  42.     A  Pepero- 
mia     Leaf      that      has 
rooted   and  produced  a 
number  of  shoots. 


Figure  44. 


Figure  45. 


Figure  47. 


Figure  46. 

Figures  4J  to  47  represent  the  succulent  leaves    of  such  plants  as   Kleimia  and    Echeveria    sending    out 

roots  and  actintr  as  nurses  to  buds  at  their  bases. 


Figure  48.     A  Pelargonium  Cutting.     Only  a   few- 
leaves  are  allowed  to  remain  on  the  shoot,  so  that  it 
may  not  lose  all  its  water  supply. 


Figure  49.      A    Carnation    Layer.       It    has    sent 

out   roots,  and   is   still   connected  with  the   parent 

plant. 


NOTES. 


ASTRONOMY. 

By  A.  C.  D.  Cro-M.melin,  B.A.,  D.Sc,  F.R.A.S. 

THE  ORBIT  OF  DELTA  ORIONIS— This  star,  the 
right-hand  member  of  the  belt,  lying  alxnost  exactly  on  the 
celestial  equator,  is  an  interesting  spectroscopic  binary. 
A  discussion  of  its  orbit,  by  Frank  C.  Jordan,  appears  in 
"  Publications  of  Allegheny  Observatory',"  Volume  III, 
part  15.  He  uses  both  his  own  and  earlier  photographs  of 
the  spectrum,  and  thus  has  obser\-ations  available  extendiirg 
over  ten  years.  The  spectrum  is  of  Type  Bl  (helium  type). 
No  secondary  spectrum  can  be  traced ;  so  evidently  there  is 
great  disparity'  in  the  light-giving  power  of  the  components. 

The  most  probable  value  of  the  period  is  5  -73257  days  ; 
the  eccentricity,  0-09  ;  the  orbital  velocity,  100  kilometres 
per  second  ;  longitude  of  periastron,  5°  in  1902,  20°  in  1910  ; 
the  recessional  velocity,'  of  the  centre  of  gravity,  23  kilo- 
metres per  second  in  1902,  15  kilometres  in  1910  ;  a  sin  i 
=7,850,000  Idlometres. 

Also,  if  »«i,  in^  denote  the  masses  of  primar>'  and  second- 
arj'  stars  (the  Sun  being  unity), 

m.?  sin^  i 

r^—. -,3  =  0-588. 

The  change  in  the  longitude  of  periastron  is  doubtful, 
as  there  is  considerable  uncertaints'  in  the  determination  ; 
it  is,  however,  in  accord  with  what  tidal  action  would  lead 
us  to  expect.  The  change  in  the  rate  of  recession  of  the 
e.g.  may  only  arise  from  the  different  personality  of  the 
obser\'ers  ;  it  may,  on  the  other  hand,  indicate  revolution 
round  a  third  member  of  the  system,  such  as  is  beheved  to 
take  place  in  the  case  of  Algol. 

There  are  many  spectroscopic  binaries  for  which  our 
ignorance  of  the  value  of  i  is  complete  :  this  is  not  the  case 
with  Delta  Orionis,  for  Mr.  Joel  Stebbins  found  some  years 
ago,  with  the  aid  of  his  sensitive  selenium  photometer, 
that  it  is  an  Algol  variable,  though  the  change  of  Ught  is 
too  small  to  detect  by  ordinary  methods.  Hence  we  see 
the  system  nearly  edgewise,  and  a  partial  eclipse  occurs  in 
each  revolution. 

If  we  assume  for  the  companion  a  mass  half  that  of  the 
primary,  and  conjecture  for  the  radii  of  the  two  one  and 
a  half  and  one  milUon  kilometres,  also  taking  the  amount 
echpsed  as  one-quarter  of  the  diameter  of  the  primary, 
i  comes  out  86°.  It  is  unnecessary  to  know  it  very  accurately, 
since  the  sine  of  an  angle  near  90°  changes  slowlj'.  Under 
these  assumptions  the  masses  come  out  10|,  5s,  that  of 
the  Sun  being  1. 

If  we  assume  equal  masses,  and  take  i=83°,  the  mass  of 
each  is  two  and  a  half  times  the  Sun's.  The  total  mass  of 
the  system  probably  hes  between  ten  and  twenty'  times  the 
Sun's.  From  the  minuteness  of  the  star's  proper  motion 
it  is  beheved  to  be  very  distant ;  hence  the  luminositv  of 
the  primarj'  is,  presumably,  very  great  in  proportion  to  its 
mass  ;  in  other  words,  its  density  is  small,  and  its  radius 
may  not  improbably  be  considerably  greater  than  that 
assumed  above.  This  would  diminish  the  value  of  sin  ;,  but 
not  enough  to  seriously  affect  the  masses. 

This  star  is  one  of  those  in  whose  spectra  the  H  and  K 
hnes  of  calcium  do  not  share  in  the  periodic  displacement. 
No  ver\'  satisfactory  explanation  of  this  peculiarity  has 
been  arrived  at,  but  it  is  supposed  to  indicate  an  extended 
calcium  cloud  enveloping  the  system.  Jlr.  Jordan  finds 
18-5  kilometres  per  second  as  the  velocity  of  this  calcium 
cloud  away  from  the  Sun.  This  is  3-5  kilometres  greater 
than  the  velocity  of  the  e.g.,  but  the  difference  is  not  large 
enough  to  lay  great  stress  upon.  He  notes  that  the  Sun's 
own  speed  is  about  eighteen  kilometres  per  second  away  from 
the  star  ;    hence  the  calcium  cloud  is  practically  at  rest 


with  reference  to  the  sidereal  system — at  least  as  regards 
the  radial  component.  This  is  in  accord  \rith  the  fact 
that  the  stars  of  early  spectral  type  have  in  general  small 
velocities.  It  will  be  of  great  interest  to  follow  this  star 
fairly  continuously,  both  with  the  spectroscope  and  photo- 
meter, to  ascertain  whether  the  motion  of  the  periascion 
and  change  in  the  speed  of  the  e.g.  are  verified.  It  is  quite 
likely  that  an  analysis  of  the  hght-curve  during  echpse 
would  give  further  information  about  the  diameters,  but 
I  have  not  at  present  access  to  the  details. 

MOULTON  AND  CHAMBERLIN'S  PLANETESI.MAL 
HYPOTHESIS. — Mr.  T.  C.  Chamberlin  gives  an  interesting 
exposition  of  this  hypothesis  in  Scientia  for  October.  The 
theory  does  not  deal  with  the  birth  of  the  Sun,  which  is 
supposed  to  have  formerly  existed  as  a  soUtary  orb.  Another 
Sun  is  supposed  to  have  passed  fairlj'  near  it  (according 
to  the  authors,  a  distance  of  a  hundred  milhon  miles, 
or  even  more,  would  not  be  too  great  to  produce  the 
effects  they  postulate  :  approaches  within  this  distance 
would  be  vastly  more  frequent  than  actual  coUisions). 
The  result  is  tidal  distortion  of  each  star,  protuberances 
being  raised  on  opposite  sides  of  them.  These  are  supposed 
to  have  reached  such  a  height  that  a  large  quantity  of 
matter  on  each  side  broke  off  from  the  parent  star  and 
commenced  to  describe  orbits  round  it,  the  moment  of 
momentum  required  for  this  revolution  being  derived  from 
the  attraction  of  the  other  star.  This  acquirement  of 
extraneous  moment  of  momentum  is  the  leading  motive 
of  the  theory  :  "  The  Sun  holds  about  seven  hundred  and 
forty-five  out  of  seven  hundred  and  forty-six  parts  of  the 
total  matter  of  the  solar  system,  wliile  it  only  carries  about 
two  per  cent,  of  its  moment  of  momentum.  This  leads  to 
the  conviction  that  a  new  agency  came  in,  after  the 
original  formation  of  the  Sun,  and  gave  to  a  very  small 
fraction  of  the  solar  matter,  after  it  had  been  drawn  out  from 
the  Sun,  a  special  endowment  of  momentum."  The  two 
streams  of  matter  would  form  a  double  spiral,  of  a  form 
that  we  meet  with  in  numerous  nebulae.  The  argument 
from  analogy  is  used  by  the  authors  to  support  their  theory 
Another  argument,  not  used  by  them,  seems  to  me  to  be  the 
constitution  of  meteors,  which  frequently  contain  a  large 
quantity-  of  hydrogen.  This  would  be  explained  if  they  had 
once  formed  part  of  the  crust  of  the  Sun,  on  the  hypothesis 
that  this  crust  had  already  solidified  before  the  approach 
of  the  other  Sun,  but  was  then  disrupted  by  tidal  action. 

I  shall  continue  this  note  next  month. 

BOTANY. 

By  Professor  F.  Cavers,  D.Sc,  F.L.S. 

EFFECTS  OF  ELECTRIC  DISCHARGE  ON  PLANTS. 
— Many  experiments  have  been  made  during  recent  years 
in  which  plants,  otherwise  under  normal  conditions,  have 
been  subjected  to  an  electric  discharge  from  an  overhead 
system  of  wires  during  a  considerable  portion  of  their 
growing  period,  and,  as  a  result,  acceleration  of  growth  and 
increase  in  yield  have  been  invariably  reported.  Since 
this  treatment  must  considerably  alter  many  factors  in 
the  plant  habitat,  and  in  the  plant's  reaction  to  this  habitat, 
it  is  difficult  to  ascribe  the  effect,  apparently  due  to  the 
electric  discharge,  to  any  particular  physiological  cause. 
Priestley,  who  has  taken  a  prominent  part  in  this  line  of 
investigation,  records  in  a  recent  paper,  in  collaboration 
wth  Knight  {Annals  of  Botany,  Volume  XXVIII),  some  of 
the  first  attempts  to  analyse  the  efiect  of  the  discharge 
upon  the  plant  by  investigating  under  laboratory  con- 
ditions the  effect  produced  by  such  discharge  upon  one 
ph5'siological  function,  namely,  respiration.  Experiments 
were  made  \\ith  small  direct  currents  at  a  relatively  low 


51 


52 


KNOWLEDGE. 


February,  1915. 


voltage  and  with  electric  discharge  at  liigh  tensions.  The 
results  show  that  direct  currents  have  no  effect  on  the 
respiration  of  peas  other  than  that  due  to  accompanying 
changes  of  temperature  ;  but  the  proportion  of  these  cur- 
rents actually  traversing  the  peas  was  probably  very  small, 
the  majority  being  taken  by  the  water  films  of  the  seeds. 
Overhead  discharge  of  low  density  has  no  effect  on  respir- 
ation ;  but  with  liigher  currents  a  definite  increase  of  the 
carbon  dioxide  output  was  observed,  this  increase  being 
wholly  attributable  to  the  rise  of  temperature  caused  by 
the  discharge.  In  the  field,  where  the  currents  are  too 
small  to  produce  any  appreciable  rise  in  temperature, 
electrification  will  have  no  effect  on  respiration,  and  an 
explanation  of  the  acceleration  of  growth  must  be  sought 
in  other  functions  of  the  plant.  The  gaseous  products  of 
the  discharge  in  air  have  no  effect  on  germinating  peas, 
but  are  injurious  to  young  seedlings.  These  results  do  not, 
of  course,  mean  that  the  acceleration  is  inexplicable,  for 
one  result  of  electrification  may  be  increased  transpiration, 
which  alone  would  account  for  a  more  rapid  attainment  of 
maturity  by  the  plant ;  while  various  observers  have  found 
that  electrification  produces  increased  activity  of  con- 
structive metabolism — the  processes  of  building  up  food 
materials  in  the  plants. 

STATISTICAL  METHODS  IN  PLANT  GEOGRAPHY. 
— For  many  years  the  Swiss  botanist  Jaccard  has  been 
investigating  in  great  detail  the  distribution  of  plants  in 
certain  definite  areas  in  alpine  meadows,  and  has  obtained 
some  interesting  results,  which  appear  likely  to  be  of  general 
application.  His  latest  paper  (Rev.  gin.  Bot.,  Volume 
XXVI)  deals  with  the  vegetation  of  some  alpine  gravel 
areas,  but  a  fuller  account  of  his  earlier  results  is  given 
in  an  English  paper  (New  Phytologist,  Volume  XI).  Having 
made  a  census  of  the  flowering  plants  growing  in  the  areas 
to  be  compared — similarly  situated  localities  of  about  the 
same  area  in  different  parts  of  the  Alps — he  applies  to  the 
analysis  of  his  results  what  he  called  the  "  coefficient  of 
community,"  that  is,  the  percentage  ratio  between  the 
number  of  species  common  to  two  district  and  the  total 
number  of  species  in  the  two  districts.  For  alpine  meadows 
he  found  that  (1)  the  value  of  this  coefficient  does  not 
depend  on  floral  richness,  but  upon  the  ecological  characters 
of  the  areas  studied ;  (2)  the  alpine  flora  is  extremely  diverse 
in  floristic  composition  ;  (3)  the  rare  species  are  most 
numerous  and  the  common  species  least  numerous  [This 
does  not  apply  to  individuals,  but  to  species]  ;  (4)  the 
coefficient  is  usually  higher  for  contiguous  than  for  distant 
areas.  He  also  uses  what  he  terms  the  "  generic  coefficient," 
that  is,  percentage  ratio  between  number  of  genera  and 
number  of  species,  and  finds  that  this  coefficient  varies 
inversely  with  the  variety  of  ecological  conditions  in  the 
areas  compared.  For  instance,  in  alpine  areas  its  value 
increases  with  altitude  ;  while  in  the  Belgian  sand-dunes 
(from  data  given  by  Massart)  it  is  greatest  (100)  under  the 
excessive  and  narrow  ecological  limits  of  the  moving 
dunes,  and  least  (73)  under  the  more  varied  conditions  of 
the  pannes  (salt  marshes).  From  his  analyses  Jaccard 
draws  the  following  general  conclusions.  The  distribution 
of  plants,  at  any  rate  in  the  alpine  zone,  is  a  resultant  of 
the  combined  action  of  three  kinds  of  factors  :  ecological 
biological  (degree  of  adaptation),  and  sociological  (com- 
petition between  species).  The  action  of  these  factors 
has  resulted  in  two  kinds  of  selection  :  an  eliminative 
selection  of  species  and  a  distributive  selection,  determining 
the  number  of  individuals  and  the  nature  of  associated 
species.  Readers  interested  in  the  subject  should  consult 
the  New  Phytologist  paper  for  details  of  Jaccard 's  interesting 
investigations. 

A  DARK-GROUND  ILLUMINATION  STUDY  OF 
PLANT  CELLS. — Until  about  ten  years  ago  the  method 
of  dark-ground  illumination  with  the  microscope  was 
regarded  simply  as  a  means  of  exhibiting  objects  with 
pretty  and  striking  effect,  and  even  now  much  less  use  has 
been  made  of  the  method  in  the  investigation  of  the  plant 


cell  than  might  have  been  anticipated.  In  a  recent  paper 
Price  (Annals  of  Botany,  Volume  XXVIII)  gives  the 
results  of  his  examination  of  various  plant  cells,  made  with 
the  object  of  seeing  whether,  by  this  method,  more  facts 
might  be  obtained  concerning  the  colloid  structure  of  the 
living  and  the  dead  cell  and  the  reactions  of  the  colloid.  He 
gives  a  brief  account  of  the  necessary  procedure,  suitable 
objects  for  study,  and  so  on,  and  the  paper  will  be  found 
very  useful  by  others  wishing  to  examine  plant  cells  by 
this  method.  The  objects  used  were  chiefly  filamentous 
algae,  spores,  and  hairs  ;  and  in  his  summary  the  author 
points  out  that  the  method  often  reveals  new  structural 
features,  and  is  useful  in  establishing  the  presence  of 
minute  particles,  which  are  difficult  to  see  or  are  unresolved 
in  direct  illumination,  though  the  method  is  restricted  in 
application,  owing  to  the  difficulty  of  selecting  suitable 
material  for  examination.  It  is  generally  recognised  that 
protoplasm  is  a  colloidal  complex  existing  both  in  the 
hydrosol  and  the  hydrogel  state,  a  hydrosol  being  a  colloidal 
solution — differing  from  an  ordinary  solution  essentially 
in  consisting  of  particles  suspended  in  a  continuous  medium 
— while  a  "  gel  "  is  a  sponge-like  body  in  which  the  con- 
tinuous phase  encloses  the  other  phase  in  a  mesh  of  cavities. 
To  a  certain  extent,  these  states  are  spontaneously  reversible. 
The  process  of  germination  of  certain  fungus  spores  showed 
the  gradual  conversion  of  the  gel  -  contents  of  the  spore 
into  a  hydrosol  on  absorption  of  water,  while  later  on 
a  formation  of  a  gel  may  occur  again.  The  nucleus  and 
chloroplast  are  evidently  specialised  parts  of  the  plasma, 
with  a  hydrogel  structure  ;  particles  and  vesicular  bodies 
("  sap  particles  "),  usually  present  in  the  cell-sap  and 
showing  a  continuous  Brownian  movement,  were  found 
to  increase  in  number  with  decreasing  vitality  of  the  cell. 
The  effects  of  plasmolysis  were  studied  with  different 
reagents,  and  it  was  found  possible  to  distinguish  an  outer 
layer  with  much  finer  structure  than  the  rest  of  the  proto- 
plasm, this  layer  being  apparently  the  part  concerned  in 
the  formation  of  the  fine  fibrils,  which  often  connect  the 
plasmolysed  protoplast  with  the  wall  of  the  cell.  A  similar 
layer  was  also  recognised  on  the  inside  of  the  protoplast 
against  the  vacuole.  The  action  of  fixing  and  coagulating 
agents  was  studied,  and  it  was  found  that  during  fi.xation 
a  change  to  an  opalescent  hydrogel  takes  place,  the  rate 
of  formation  and  the  structure  of  the  gel  differing  in  different 
plant  material  and  with  different  agents. 


CHEMISTRY. 

By  C.  AiNSWoRTH  MircHELL,  B.A.  (Oxon),  F.I.C. 

GERMANY'S  MOTOR  FUEL —Three  recent  issues  of 
the  Zeitschrift  fur  angewandte  Cliemie  which  have  recently 
come  to  hand  by  way  of  a  neutral  country  show  the  straits 
to  which  Germany  has  already  arrived  from  the  shortage 
of  petrol. 

According  to  Dr.  Hempel  (page  521),  Germany,  in  1913, 
produced  179,800  tons  of  petrol  and  160,000  tons  of  benzene 
(benzol),  nearly  a  third  of  which  was  exported  to  France, 
while  in  the  year  1912-13  the  country's  production  of 
alcohol — mainly  from  potato  starch — reached  3,753,265 
hectolitres.  Alcohol  thus  appears  to  be  the  natural  sub- 
stitute for  petrol,  and  Dr.  Hempel  states  that,  by  order  of 
the  Kaiser,  all  motor-cars  in  Berlin  have  been  adapted  to 
use  alcohol  as  well  as  petrol. 

The  relative  heats  of  combustion  of  the  various  possible 
fuels  are  as  follows  :  Petrol,  9500  to  10,500  ;  pure  benzene, 
10,260  ;  commercial  benzene  (benzol),  9550  to  10,000  ; 
pure  alcohol,  7402  ;  ninety-five  per  cent,  alcohol,  5875  ; 
and  pure  naphthalene,  9628-3  calories  per  kilogramme. 

In  practice  a  mixture  of  four  parts  of  ninety-five 
per  cent,  alcohol  with  one  part  of  benzene,  containing 
two  hundred  grammes  of  naphthalene  per  htre,  gave 
the  same  results  as  ordinary  petrol ;  whereas  the  use  of 
alcohol  by  itself  tended  to  rust  the  tubes  of  the  carburettor. 


February,  1915. 


KNOWLEDGE. 


53 


Dr.  Dieterich  (page  543)  describes  various  mixtures  of 
alcohol  with  benzene,  commercial  acetone,  and  petroleum 
oil  as  being  suitable  for  motor  engines,  but  points  out  that 
in  each  case  preliminary'  heating  of  the  carburettor  and 
reduction  of  the  supply  of  air  are  necessary. 

Dr.  Mohr  (page  558)  discusses  the  suitability  of  the  various 
mixtures  suggested  by  Dr.  Hempel  and  Dr.  Dieterich.  In 
his  experience  only  the  simplest  mixtures  of  alcohol  with 
hydrocarbons  have  given  satisfactory  results.  Thus  he 
has  found  suitable  for  the  purpose  a  mixture  of  alcohol  and 
benzene  in  equal  parts ;  or  of  alcohol,  one  half ;  benzene, 
a  quarter ;  and  petrol,  a  quarter.  Naphthalene  is  an 
unsuitable  ingredient  owing  to  its  forming  crystalline 
deposits.  Attempts  have  been  made  to  use  alcohol  con- 
taining about  one  half  per  cent,  of  ammonium  perchlorate, 
but  these  were  unfavourable  owing  to  the  chlorine 
compounds  formed  in  the  explosion  attacking  the  metal. 
All  three  chemists  express  their  confidence  that  Germany 
will  be  able  to  produce  sufficient  alcohol  for  their  motor 
engines,  and  that  all  mechanical  difficulties  can  be  over- 
come. They  mention  that  about  a  dozen  firms  are  now 
manufacturing  carburettors  specially  adapted  for  burning 
alcohol  and  mixtures  of  alcohol  and  benzene.  The  addition 
of  a  small  amount  of  motor  oil  is  suggested  as  a  means  of 
preventing  rusting  of  the  tubes  by  the  alcohol. 

PROPERTIES  OF  XAPHTHENIC  ACIDS.— The  waste 
alkaline  lyes  from  the  refining  of  petroleum  oils  contain  a 
large  proportion  of  compounds  which  are  known  as 
"  naphthenic  acids."  They  can  readily  be  separated  by 
treating  the  lyes  with  a  mineral  acid,  and,  owing  to  the  in- 
creasing scarcity  of  coconut  and  palm  oils,  are  of  grovring 
importance  for  the  manufacture  of  soaps,  especially  for  such 
as  -irill  give  a  lather  \\ith  salt  water.  Unfortunately,  their 
use  in  this  direction  is  restricted  by  their  unpleasant  odour, 
and  attempts  are  being  made  in  many  directions  to  obviate 
this  drawback. 

In  the  last  issue  of  Les  Mati&res  Grasses  (1914,  VII,  4115), 
M.  E.  Schmitz  gives  an  account  of  his  systematic  experiments 
upon  the  deodorisation  of  the  acids.  He  found  that,  by 
repeatedly  treating  them  \v'ith  dilute  sodium  carbonate 
solution,  an  insoluble  compound  of  phenolic  character, 
which  showed  the  characteristic  odour  in  an  intensified 
degree,  could  be  separated,  while  the  final  product  had  only 
a  very  faint  odour.  The  dark,  insoluble  "  oil  "  gave  an 
intense  bluish-green  colour  with  copper  salts,  and  could 
be  used  as  the  basis  of  a  lacquer  for  wood.  Attempts  to 
deodorise  the  naphthenic  acids  by  hj-drogen  were  unsuccess- 
ful, but  treatment  with  ozone  for  about  tivo  hours  reduced 
the  odour  to  some  extent,  and  could  be  used  as  a  practical 
process  after  removal  of  the  evil-smelling  phenolic  sub- 
stances by  means  of  sodium  carbonate  as  described. 


GEOGRAPHY. 

By  A.  Scott,  M.A.,  B.Sc. 

MAPS     AND     PHYSICAL     GEOGRAPHY.— In     the 

Geographical  Journal  for  January  Mr.  Alan  Ogilvie  discusses 
the  utihty  of  our  available  maps  from  the  point  of  view  of 
the  physical  geographer,  and  makes  a  number  of  suggestions 
regarding  the  ways  in  which  they  might  be  made  more 
useful.  As  it  has  not  been  found  possible,  so  far,  to  combine 
the  virtues  of  the  different  editions  of  the  Ordnance  Survey 
maps,  all  editions  should  be  kept  on  sale.  Similarly,  atlases 
of  land-form  types,  on  one-inch  and  six-inch  scales,  would 
be  of  great  service  to  teachers.  The  chief  defect  of  geological 
maps,  from  the  geographer's  point  of  view,  is  that  it  is  often 
impossible  for  the  non-geologist  to  determine  from  such 
maps  the  hthology  of  the  district,  and  this  can  only  be 
remedied  by  the  preparation  of  lithological  maps.  Other 
things  which  might  be  indicated  on  these  maps  are  the 
porosity  and  comparative  resistance  of  the  various  strata. 
In  the  investigation  of  land  forms,  much  useful  information 
could  be  obtained  from  maps  showing  what  processes  have 
been  most  effective,  and  also  the  stage  of  maturity  at  which 


the  various  features  have  arrived.  In  connection  with 
water  supply,  it  is  suggested  that  not  only  might  the 
different  types  be  cartographically  indicated,  but  also  the 
variation  of  headwaters  and  river  volumes.  Other  pheno- 
mena which  might  lend  themselves  to  more  accurate  map- 
ping than  they  have  hitherto  received  are  meteorological 
conditions,  vegetation,  and  oceanographical  and  soil-survey 
data. 

GEOGRAPHY  AND  STRATEGY.— There  are  two 
principal  ways  in  which  geographical  conditions  affect 
strategy  :  one  with  regard  to  lines  of  advance  and  the 
other  with  regard  to  obstacles.  The  former  are  determined 
by  the  occurrence  of  level  country  or  of  "  defiles,"  such  as 
river  valleys.  According  to  Hilaire  Belloc  [Geographical 
Journal,  January,  1915),  obstacles  are  of  five  types  :  rivers, 
including  canals,  forests,  hill  countrj'.  deserts,  and  marshes. 
Rivers  are  never  permanent  obstacles,  though  they  may  have 
a  great  tactical  value  temporarily,  such  as  the  Ourcq  had 
during  von  Kluck's  retirement.  Forests  are  serious  obstacles 
unless  there  are  numerous  defiles,  an  example  in  the  present 
war  being  the  Forest  of  Argonne.  HUls  vary  in  importance, 
and  at  one  period  those  along  the  Aisne  proved  invaluable 
to  the  German  Army.  As  campaigns  have  seldom  been 
carried  out  in  deserts,  there  are  few  data  from  which  to 
deduce  the  value  of  such  country.  IMarshes  provide  the 
greatest  obstacle  of  all,  as  it  is  practically  impossible  to 
entrench  in  them.  This  has  been  well  shown  by  the 
campaign  in  the  Yser  district. 

GEOLOGY. 

By  G.  W.  Tyrrell,  A.R.C.Sc,  F.G.S 

PERMO-CARBONIFEROUS  BRECCIA  OF  ENGLISH 

INIIDLANDS. — The  chief  exposures  of  this  deposit  occur 
near  Birmingham.  It  consists  of  sandstones  and  marls, 
with  occasional  sheets  of  very  angular  breccia,  which  is 
formed  of  blocks  of  volcanic  rocks,  grits,  slates,  and 
limestones  identical  with  rocks  from  the  Welsh  border. 
This  puzzling  deposit  has  been  variously  ascribed  to  volcanic, 
glacial,  or  lacustrine  agencies ;  but  H.  T.  Ferrar,  in  a  paper 
read  before  the  British  Association,  Australia,  1914,  shows 
that  it  closely  resembles  certain  desert  formations.  He 
instances  especially  the  material  which  partially  fills  the 
wadis,  or  steep-sided  gorges,  of  the  folded  mountain-chain 
forming  the  watershed  between  the  Nile  and  the  Red  Sea. 
"  The  climate  is  arid,  with  occasional  heavy  thunderstorms, 
causing  temporary-  currents,  which  sweep  for%vard  all  rock 
material  loosened  during  the  prevailing  dry  climate." 
This  material  is  very  angular  and  fresh,  and,  in  slipping 
down  the  hillsides,  or  in  course  of  violent  water  transport, 
the  blocks  are  frequently  scratched,  grooved,  and  even 
shattered  by  mutual  impact.  Huge  blocks  may  be  carried 
as  much  as  a  hundred  miles  down  the  wadi  channels  by 
water,  and  hence  it  is  not  necessary  to  invoke  the  agency 
of  ice  to  explain  the  occurrence  of  large  blocks  in  similar 
deposits.  The  valley-fill  of  most  wadis  in  the  Eastern 
Desert  of  Egj'pt  is  an  unconsolidated  breccia,  so  similar 
to  that  of  the  Permo-Carboniferous  in  the  English  Midlands 
that  there  can  be  little  doubt  that  the  tivo  originated  under 
similar  climatic  conditions. 

METEOROLOGY. 

By  \ViLLL\M  Marriott,   F.R.Met.Soc. 

THE  WEATHER  OF  FEBRUARY.— February  is  the 
last  month  of  winter,  and  extremely  variable  in  character. 
There  is  an  old  proverb : 

"  February  fill  dyke,  be  it  black  or  be  it  white  ; 
But,  if  it  be  white,  it 's  the  better  to  like," 

but  more  recent  observations  tend  to  set  aside  the  old 
proverb.  In  severe  winters  the  frosts  of  the  two  previous 
months  continue,  or  return  with  great  intensity  ;  while 
on  several  occasions  the  greatest  cold  of  the  year  has 
occurred  in  this  month.     It  was  a  very  cold  month  in  the 


54 


KNOWLEDGE. 


February,  1915. 


vears  1S45,  1S55,  1SS6,  and  coldest  of  all  in  1S95.  It  was 
a  very  mild  month  in  the  years  1850,  1867,  1869,  1872, 
1S77,  1903,  and  1914. 

The  average  mean  temperature  at  Greenwich  for  Feb- 
ruaiy  is  39° -5  ;  in  1869  it  was  as  high  as  45° -6,  while  in 
1895  it  was  as  low  as  29°-l.  The  average  maximum  tem- 
perature is  45° -2  ;  the  highest  mean  was  51°-8,  in  1869, 
and  the  lowest  35° -2,  in  1895.  The  average  minimum 
temperature  is  34° -3  ;  the  liighest  mean  was  39° -7,  in  1869, 
and  the  lowest  22° -8,  in  1895.  The  absolute  highest  tem- 
perature recorded  w-as  63°-9,  in  1899,  on  the  10th,  and 
the  absolute  lowest  6° -9,  in  1895,  on  the  8th.  The  average 
number  of  days  on  which  tlie  temperature  falls  to  or  below 
the  freezing-point  is  ten.  In  1895  the  temperature  was 
continuously  below  the  freezing-point  for  seven  days, 
from  the  5th  to  the  1 1th. 

The  average  rainfall  for  the  month  of  February  is  1  •52-in.  ; 
the  greatest  amount  was  4-03-in.,  in  1866,  and  the  least 
0-04-in.,  in  1821.  The  heaviest  fall  in  one  day  was  2-89-in., 
in  1831,  on  the  7th.  The  average  number  of  "  rain  days  " 
{i.e.,  on  which  0-01-in.  fell)  is  12-4  ;  the  greatest  number  of 
days  was  twenty-two,  in  1893.  and  the  least  three,  in  1857. 
Snow  falls  on  the  average  on  three  days.  The  average 
amount  of  bright  sunshine  in  the  City  of  London  is  thirty- 
one  hours,  but  at  Kew  Observatory,  Richmond,  the  amount 
is  fifty-six  hours. 

The  average  barometric  pressure  for  February  is 
29-972-in.  ;  the  highest  mean  was  30-473-in.,  in  1891, 
and  the  lowest  mean  was  29-499-in.,  in  1776.  There  is 
thus,  in  the  neighbourhood  of  London,  a  variation  of  nearly 
an  inch  in  the  monthly  nieans.  The  highest  recorded  read- 
ing in  the  British  Isles  was  31-007-in.  at  Gordon  Castle, 
Banff,  in  1808,  on  the  24th. 

From  a  discussion  of  the  results  of  the  observations  in 
England  and  Wales  during  the  thirty  years  1881-1910  it 
appears  that  when  the  barometric  pressure  is  high  in 
February  it  is  usuallv  followed  by  low  pressure  in  March, 
and  vice  versa  ;  and  that  a  wet  Februarj'  is  usually  followed 
by  a  dry  March. 

"  If  Candlemas  Day  *  be  fair  and  bright, 
Winter  will  have  another  flight  ; 
But  if  Candlemas  Day  bring  clouds  and  rain, 
Winter  is  gone  and  won't  come  again." 

*  February  2nd. 

RELATIVE  HUMIDITY  IN  ENGLAND  AND  WALES. 
— At  the  December  meeting  of  the  Royal  Meteorological 
Society  Mr.  W.  F.  Stacey  read  a  paper  on  "  The  Distribution 
of  Relative  Humidity  in  England  and  Wales."  He  had 
prepared  mean  monthly  and  annual  maps  of  relative 
humidity  based  on  the  9  a.m.  dry  and  wet  bulb  thermometer 
obser\-ations  made  at  over  ninety  stations  during  the  ten 
years  1901-10.  An  examination  of  the  maps  shows  that 
in  winter  the  air  over  the  interior  of  the  country  is  more 
moist  than  that  over  the  coastal  regions  ;  that  the  minimum 
relative  humidity  occurs  earlier  in  the  year  in  the  western 
parts  of  the  country  than  in  the  eastern  ;  that  in  summer 
the  air  over  the  interior  of  the  country  is  drier  than  that 
over  the  coastal  regions  ;  and  that  the  smallest  range  of 
humidity  is  found  in  the  west  and  the  greatest  in  the 
interior  towards  the  east.  The  distribution  of  temperature 
is  the  chief  determining  factor  in  the  distribution  of  relative 
humidity  ;  while  sea  influence,  the  direction  and  character 
of  prevailing  winds,  the  configuration  of  the  country,  all 
have  important  effects  on  temperature,  and  therefore  on 
relative  humidity. 

MICROSCOPY. 

By  J.  E.  Barnard,  F.R.M.S. 

THE  MICROSCOPE  AND  THE  WAR.— That  there  is 
any  connection  between  the  microscope  and  the  present 
disastrous  European  War  is  not  immediately  apparent. 
A  little  deliberation,  however,  will  show  that  both  the  use 
and  the  production  of  microscopes  commercially  are  seriously 
affected.      If  we   consider   the   matter   from   the   point   of 


view  of  production,  it  is  quite  clear  that  the  number  of 
instruments  available  at  the  present  moment  is  not  so  great 
as  formerly.  A  very  large  number  were  previously  imported 
from  the  Continent — principally  from  German^' — and  these 
are  not  now  obtainable.  On  the  other  hand,  the  use  of  the 
instrument  has  been  restricted,  so  that  the  demand  in 
general  is  not  so  great.  British  manufacturers  have  no 
doubt,  to  some  extent  at  least,  stepped  into  the  breach, 
and  are  producing  to  the  utmost  of  their  capacity.  This, 
however,  does  not  mean  very  much,  as  nearly  all  manu- 
facturing opticians  are  fully  occupied  in  making  optical 
instruments  of  various  sorts  for  Ann}-  purposes.  In  some 
respects  the  position  of  the  microscope  industry  is  analogous 
to  the  anilme  dye  trade.  The  microscope  in  its  earlier  days 
was  almost  entirely  a  British  production,  whereas  it  has,  to 
a  large  extent,  especially  on  its  optical  side,  passed  into  the 
hands  of  Continental  makers.  If  we  read  through  the  earlier 
numbers  of  The  Journal  of  the  Royal  Microscopical  Society, 
it  is  evident  that  about  thirtj^  to  forty  years  ago,  when  the 
microscope  was  in  course  of  development,  British  makers 
were  in  the  very  front  rank.  The  influence  of  their  design 
and  method  of  construction  is  still  largely  felt ;  in  fact,  it 
is  not  too  much  to  say  that  at  the  present  time,  if  a  micro- 
scope of  the  very  finest  construction  is  wanted,  it  is  still 
possible,  and  perhaps  even  advisable,  to  get  one  of  British 
manufacture.  One  of  the  features  of  the  Continental 
instrument  has  been  its  simplicity ;  and  in  this  respect  there 
is  something  to  be  said  for  it ;  but  in  evol\-ing  such  a  type. 
Continental  makers  have  striven  more  for  cheapness  than 
to  provide  an  instrument  that  is  thoroughly  efficient.  If 
we  take  the  outstanding  characteristic,  for  instance,  of  the 
Continental  stand,  the  horseshoe  foot,  we  are  at  once  con- 
fronted with  a  design  which  has  nothing  much  to  recom- 
mend it ;  whereas  the  British  type  of  tripod  foot  is  in  every 
respect  more  stable,  and  a  better  method  of  support  in 
whatever  position  the  instrument  may  be  used. 

The  sub-stage,  which  is  now  recognised  as  of  primary 
importance,  the  Continental  makers  have  reduced  to  its 
simplest  proportions,  and  in  some  respects  have  made  it 
almost  a  useless  feature  of  the  instrument  owing  to  the  lack 
of  centring  adjustment.  The  British  manufacturers  have 
never  been  behindhand  in  this  particular,  and  their  instru- 
ments of  the  better  class  have  been  such  that  one  might  use 
them  for  the  most  exacting  work. 

That  most  of  the  improvements  in  microscope  design 
have  been  of  British  origin  is  a  matter  of  common  know- 
ledge, and  it  is  only  necessary  to  consult  the  earlier  Uterature 
of  the  subject  to  realise  this.  It  is  hoped,  therefore,  that 
British  makers  will  not  lose  the  opportunity  that  has  pre- 
sented itself,  of  recovering  at  least  a  large  part  of  the  trade 
that  they  have  lost,  and  that  they  will  set  themselves  to  so 
deal  with  the  matter  that  when  competition  arises  again 
there  will  be  real  strength  behind  it  to  meet  every  possible 
contingenc}'.  That  the  Continental  makers,  particularly 
those  of  Germany,  have  not  relied  on  cheap  labour,  but  on 
specialisation  and  systematic  methods  of  production,  is 
beyond  question  ;  and  unless  the  British  makers  are  pre- 
pared to  launch  out  and  do  their  part  in  this  direction  there 
is  perhaps  little  hope  for  them  in  the  future.  So  far  as  the 
optical  side  is  concerned.  Continental  makers  have  been 
very  much  to  the  fore.  It  is  no  uncommon  thing  for  a 
microscope  of  best  British  design  and  manufacture  to  be 
fitted  with  objectives  of  Continental  make,  and  that,  not 
because  they  are  cheaper,  but  rather  because  they  are  better 
in  quality,  the  price  in  some  cases  being  substantially 
higlier  than  those  of  British  origin.  In  this  respect  it  is 
somewhat  reassuring  to  know  that  at  least  two  British 
firms  are  making  a  feature  of  apochromatic  objectives,  and 
there  is  little  doubt  that  these  will  be  in  eveiy  respect 
equal  to  those  from  the  Continent.  When  the  apochromatic 
objective  was  first  brought  out  there  was  a  very  definite 
distinction  between  it  and  the  achromatic  object  which 
had  been  in  general  use  up  to  that  time.  Even  now  the 
difference  between  the  true  apochromatic  objective  and 
the  ordinary  objective  is  a  fundamental  one,  although 
there  are  many  objectives  which  do  to  some  extent  bridge 


February.  1915. 


KNOWLEDGE. 


the  gap.  A  lens  may  be  ver^-  well  corrected,  in  the  sense 
that  some  are  described  as  semi-apocliromatic,  but  it 
does  not  give  it  those  exact  quahties  which  the  apo- 
chromatic  objective  should  possess.  That  British  makers 
are  able  to  comply  with  the  conditions  is  beyond  question, 
and  it  is  to  be  hoped,  now  that  the  Continental  supply  is 
stopped,  users  in  this  countrv  will  realise  that  the  production 
of  the  best  optical  firms  here  is  Ukely  to  be  equal  in  every 
respect  to  that  of  Continental  origin. 

THE  CARE  OF  A  MICROSCOPE.— It  is  no  uncommon 
thing,  particularly  in  laboratories,  to  see  an  ordinar\' 
duster  or  some  other  dirtj'  cloth  used  for  cleaning  lenses 
or  other  optical  parts  of  a  microscope.  This  is  a  most 
pernicious  habit  from  every  point  of  \'iew.  Nowadays  the 
polish  on  optical  surfaces  is  of  a  high  order,  and  anything 
which  tends  to  destroy  this  polish  interferes  \\'ith  the  per- 
fection of  the  image,  and  causes  loss  of  light.  If  hnen  is 
used  for  cleaning  purposes,  it  should  be  old,  and  must  be 
thoroughly  wEished  before  use,  so  that  it  is  cleansed  from 
all  dirt  and  grit.  A  better  method,  particularly  when 
working  ^\•ith  oil-immersion  objectives,  is  to  use  Japanese 
rice  paper,  which  is  now  easily  procurable,  and  is  very  soft 
and  clean.  A  small  piece  of  this  may  be  torn  off,  and  the 
lenses  carefully  wiped  with  it  and  the  piece  thro^vn  away. 
This  will  be  found  less  expensive,  less  troublesome,  and  more 
efiective  than  using  iinen  or  cloth  of  any  description.  Any 
optical  parts,  even  if  temporarily  out  of  use,  should  not  be 
left  uncovered  on  the  working  bench.  For  this  purpose  an 
ordinary  glass  mav  be  inverted  and  placed  over  the  lens,  or 
a  small  bell  jar,  purchasable  for  a  few  pence,  may  be  used. 
The  brass  cases  for  objectives  should  always  be  laid  on  the 
bench  with  both  bottom  and  top  inverted,  so  that  no  dust 
can  enter. 

THE  QUEKETT  MICROSCOPICAL  CLUB.— The  five 
hundred  and  fourth  ordinan,-  meeting  of  tlie  Quekett 
Microscopical  Club  was  held  on  Tuesday,  January-  26th, 
at  20,  Hanover  Square,  W.  ;  the  President,  Professor 
Arthur  Dendy,  D.Sc,  F.R.S.,  in  the  chair.  Three 
gentlemen  were  elected  members,  and  four  others  were 
nominated  for  election.  The  names  of  officers  nominated  by 
the  Committee  for  the  ensuing  year  were  read,  being  sub- 
stantially the  same  as  at  present,  with  Professor  Dendy 
again  as  President.  The  members  proposed  the  names  of 
gentlemen  to  serve  on  the  Committee  to  fill  the  vacancies 
caused  by  the  retirement  of  senior  members.  The  ballot 
will  take  place  at  the  annual  meeting. 

Vice-President  Professor  E.  A.  Minchin,  M..\.,  F.R.S., 
then  gave  a  paper,  "  Notes  on  Flea  Anatomy."  He  said 
that,  although  the  main  purpose  of  his  researches  was  to 
trace  the  development  of  the  Trj-panosomes  found  in  the 
rat  flea,  ha\'ing  with  the  help  of  a  friend  dissected  about 
one  thousand  seven  hundred  fleas,  it  was  ine\-itable  that  an 
intimate  knowledge  of  the  minuter  structure  should  be 
acquired.  He  then  described  the  instruments  and  the 
methods  employed,  and  gave  a  full  account  of  the  anatomy 
and  histolog3'  of  the  internal  organs,  comprised  under  the 
following  heads  :  (1)  Notes  on  the  abdominal  nervous 
system,  sho\ring  the  curious  difference  between  the  male  and 
the  female  ;  (2)  on  the  male  reproductive  system  ;  (3)  on  the 
female  reproductive  system  ;  (4)  on  the  stellate  muscle- 
cells  of  the  oesophagus.  The  lecture  was  of  a  most  interesting 
character,  especially  to  the  audience  to  whom  it  was 
addressed,  appealing  particularly  to  microscopists.  It  was 
illustrated  by  lantern  diagrams  thrown  on  the  screen,  and 
by  a  series  of  beautiful  micro-preparations  exlubited  under 
microscopes  on  the  table.  These  slides  Professor  Minchin 
has  presented  to  the  Club,  and  they  will  be  added  to  the 
cabinet  for  the  future  use  of  members.  Professor  Dendy 
made  a  few  appreciative  remarks,  and  proposed  a  vote  of 
thanks  to  the  lecturer,  which  was  heartily  accorded  by 
acclamation. 

The  next  ordinary  meeting  will  take  place  on  Tuesday, 


Februarv  23rd,  when,  after  the  usual  business  of  the  annual 
meeting.  Professor  Dendv  will  deliver  the  Presidential 
address,  his  subject  being  "  The  Biological  Conception  of 
Individualitv." 

T    B. 

PHOTOGRAPHY. 

By  Edgar  Senior. 

THE  ELIMINATION  OF  THE  SOLUBLE  SALTS 
.\ND  "HYPO"  FROM  THE  GEL.\TINE  FILM.— In 
these  days  of  huny-  and  scurry  there  is  a  growing  tendency 
to  give  but  little  attention  to  the  fixing  and  washing  of 
negatives  and  prints.  With  the  idea  of  saving  time,  they 
are  often  imperfectly  fixed,  and  still  more  often  imperfectly 
washed.  Man^'  workers  appear  to  lose  sight  of  the  fact 
that  it  is  false  economy  to  withdraw  either  negatives  or 
prints  too  soon  from  the  fi.xing  bath,  as,  when  properly 
fixed,  they  can  be  freed  from  soluble  silver  salts  and  "  hypo  " 
much  more  rapidly  than  otherwise  would  be  the  case. 
.\s  already  pointed  out  in  these  columns,  it  is  a  good  plan 
to  use  tvvo  fixing  baths,  the  second  one  ensuring  a  complete 
conversion  of  the  silver  salts  into  the  soluble  variety',  which 
readily  diffuse  out  in  the  washing  water.  Of  the  various 
processes  through  which  a  negative  passes  it  can  be  said 
that  there  are  few  of  greater  importance  than  thorough 
washing,  for  unless  this  be  properly  done  endless  trouble 
will  arise  in  any  after  treatment  that  may  be  found  necessary. 
Then,  again,  although  there  are  many  excellent  washers  on 
the  market,  the  amateur  often  makes  use  of  some  domestic 
utensil,  which  is  quite  unfitted  and  unsuitable  for  the  pur- 
pose. In  any  case,  whatever  kind  of  appliance  be  employed 
for  washing,  it  should  be  borne  in  mind  that,  as  the  "  hypo  " 
and  silver  salts  leave  the  film,  their  weight  causes  them  to 
sink  to  the  bottom  of  the  vessel,  whence  they  should  be 
rapidly  syphoned  away. 

FUGITIVE  SILVER  PRINTS.— It  is  often  stated  that 
silver  prints  made  years  ago  were  more  permanent  than 
many  produced  of  late,  some  of  which  show  signs  of  fading 
after  a  few  months.  As  an  explanation,  the  class  of  negative 
used  has  generally  been  taken  into  account,  as  in  the  early 
days  the  negatives  employed  were  much  denser,  the  printing 
paper  (albuminisedl  was  salted  in  a  strong  bath,  and  the 
printing  carried  to  a  greater  depth  and  more  gold  deposited 
in  toning.  Then,  again,  the  washing  was  more  thorough, 
and  performed  more  quickly.  Long  wasliing  degrades  the 
brilliancy  of  the  prints.  The  old  method  of  working  was  to 
wash  the  prints  in  large  dishes  alternately  in  cold  and  warm 
water,  well  draining  between  each  change,  the  prints  by 
this  method  being  practically  freed  from  "  hypo  "  in  about 
twentj'  minutes.  Then  the  prints  were  made  from  denser 
negatives  upon  paper  sensitised  with  a  strong  silver  bath, 
and  fixed  in  a  stronger  fixing  bath — in  many  cases  in 
two  fixing  baths — and  then  quickly  washed ;  and  to 
treatment  of  this  nature  has  been  ascribed  the  secret  of 
their  permanence.  It  has  also  been  found  that  prints  which 
are  thoroughly  fixed,  but  imperfectly  washed,  are  more 
permanent  than  those  that  have  received  a  thorough  wash- 
ing, but  have  been  imperfectly  fixed.  There  is  httle  doubt, 
however,  that  the  mounts  employed  have,  in  many  cases, 
been  the  cause  of  fading :  among  prints  in  the  possession  of 
the  writer,  made  upon  albuminised  paper,  some  mounted  and 
others  unmounted,  it  is  usually  the  mounted  ones  that  have 
faded  the  most,  ^^^len  gelatino-chloride  paper  was  first 
introduced  we  were  told  that,  in  a  very  short  time,  it  would 
entirely-  displace  albuminised  paper,  and  that  the  prints 
made  upon  it  would  be  permanent ;  the  latter  claim, 
however,  has  not  been  realised  in  practice.  Prints  made 
upon  gelatino-chloride  papers  when  carefully  worked  do 
appear  to  be  more  permanent  than  those  made  upon  the 
older  albuminised  papers,  but  it  would  be  incorrect  to  call 
them  permanent.  The  degree  of  permanence  appears  to 
depend  to  a  considerable  extent  upon  the  method  of  toning 


56 


KNOWLEDGE. 


February,  1915. 


adopted.  In  our  own  practice  we  long  ago  discarded 
the  combined  bath,  and  always  resort  to  separate  toning 
and  fixing,  making  up  the  toning  bath  the  moment  before 
it  is  wanted,  being  careful  not  to  be  too  sparing  of  gold, 
as  it  is  in  the  use  of  this  in  sufficient  quantity  that  the 
secret  of  obtaining  good  tones  lies.  If,  after  toning,  the 
prints  are  fixed  in  two  separate  fixing  baths,  consisting  of 
three  ounces  of  "  hypo  "  dissolved  in  twenty  ounces  of 
water,  and  afterwards  rapidly  washed,  good  prints  should 
be  obtained,  possessing  a  reasonable  amount  of  permanence. 

RESTORING   FADED   SILVER   PRINTS.— According 
to  an  account  by  Professor  Namias,  recently  published  in 
the  Photographische  Korrespondeiiz,  faded  silver  prints  may 
be  restored   by   means   of  the   following   treatment.     The 
prints  are  first  bleached  in  a  solution  of — 

Copper  Sulphate         ...         ...       5  grains 

Common  Salt  ...  ...     25        ,, 

Water  ...  ...  ...        1  ounce 

The  bleached  image,  consisting  of  silver  chloride,  is  then 
well  washed,  and  may  be  darkened  by  redevelopment 
with  any  of  the  ordinary  developers.  The  greatest  vigour  is, 
however,  according  to  Professor  Namias,  obtained  by  the 
use  of  sodium  stannate.  For  this  purpose  a  one-per-cent. 
solution  of  stannous  chloride  is  taken,  and  a  ten-per-cent. 
solution  of  caustic  soda  added  until  the  precipitate  first 
formed  is  just  redissolved.  The  print  is  then  placed  in  this 
until  darkened,  after  which  it  is  well  washed. 


PHYSICS. 

By  J.  H.  Vincent,  M.A.,  D.Sc,   A.R.C.Sc. 

FABRY  AND  PEROT'S  INTERFEROMETER.— This 
instrument  is  of  exceedingly  simple  construction,  and 
consists  essentially  of  a  pair  of  flat  pieces  of  glass.  The  glass 
plates  are  placed  with  two  surfaces  separated  from  each 
other  by  a  layer  of  air,  the  opposed  surfaces  being  partially 
silvered.  The  silvering  can  be  best  carried  out  by  cathodic 
deposition.  The  surfaces  of  the  plates,  which  are  to  be 
silvered  and  placed  facing  each  other,  must  be  absolutely 
true  planes,  and,  when  mounted,  adjustments  must  allow- 
them  to  be  brought  accurately  parallel  to  each  other.  In 
the  interferometer  the  distance  of  the  glass  plates  from 
each  other  is  capable  of  adjustment,  while  in  another  form 
of  the  apparatus  this  distance  is  fixed.  When  truly  mono- 
chromatic light  passes  through  the  plates,  the  layers  of 
silver,  and  the  air  gap,  it  does  so  in  a  number  of  ways.  One 
portion  goes  straight  through,  another  is  reflected  from  the 
second  layer  of  silver,  then  from  the  first  layer,  and  then 
goes  on  to  join  the  first  portion.  The  second  part  of  the 
light  has  thus  been  reflected  twice  ;  the  first  has  suffered 
no  reflection.  A  third  portion  comes  through  the  plates 
after  four  reflections,  a  fourth  after  six  reflections,  and  so 
on.  The  different  portions  into  which  the  light  is  divided 
will  conspire  together  if  the  increase  in  length  of  path  for 
the  successive  parts  is  an  exact  whole  number  of  wave- 
lengths, so  that,  if  the  plates  be  viewed  with  a  telescope 
focused  on  infinity,  a  system  of  circular  interference 
bands  will  be  seen.  The  bands  are  due  to  the  obliquity  of 
the  paths  of  all  the  rays  except  those  striking  the  plates 
normally.  If  now  the  light  is  nearly,  but  not  quite,  mono- 
chromatic ;  if,  for  instance,  it  consists  of  Ught  of  two  different 
but  closely  approximating  wave-lengths,  two  systems  of 
fringes  will  be  formed,  one  for  each  kind  of  light.  "  Thus  the 
apparatus  is  a  true  spectrometer,  and  can  be  used  to 
separate  the  components  of  spectral  lines. 

APPLICATIONS  OF  FABRY  AND  PEROT'S  INTER- 
FEROMETER,— The  instrument  has  been  used  by  Fabry 
and  P6rot  in  the  investigation  of  the  intimate  structure  of 
spectrum  lines.  Thus  they  showed  that  the  green  line  of 
thallium  w^as  triple,  the  main  line  having  two  weak  com- 
panions towards  the  red  end  of  the  spectrum,  and  measured 
the    differences    between    the    wave-lengths    accurately  : 


the  red  cadmium  line  was  proved  to  be  simple.  Another 
application  was  for  the  exact  comparison  of  widely  differing 
wave-lengths  ;  in  these  experiments  the  half-silvered 
plates  were  separated  by  as  much  as  3-2  centimetres. 

THE  ETALON  INTERFEROMETER —In  1902  Fabry 
and  Perot  began  to  use  a  modified  form  of  their  inter- 
ference apparatus,  which  they  term  an  "  etalon,"  or 
standard.  This  is  derived  from  the  more  elaborate  form 
by  removing  the  facilities  for  altering  the  distance  between 
the  plates,  which  are  held  at  a  fixed  distance  apart  by 
three  pieces  of  invar.  This  material  is  practically  inex- 
pansible  by  heat,  so  that,  when  once  the  distance  separating 
the  plates  has  been  measured,  it  is  capable  of  being  treated 
as  sensibly  constant.  The  fine  adjustment  for  parallelism 
of  the  silvered  plates  is  made  by  springs,  which  can  be 
pressed  down  by  screws  on  to  the  plates  over  the  distance 
pieces,  which,  by  their  compression,  enable  their  effective 
thickness  to  be  varied.  One  method  of  calibrating  the 
6talon  is  by  comparison  with  the  air  film  of  an  interfero- 
meter whose  plates  can  be  gradually  separated.  The 
measurement  of  the  thickness  having  been  carried  out, 
the  6talon  can  be  used  to  determine  an  unknown  wave- 
length. By  its  means  many  lines  in  the  spectra  of  the  metals 
and  in  the  solar  spectrum  have  been  accurately  measured, 
these  results  being  now  regarded  as  more  reliable  than  those 
found  by  other  methods. 

DIATHERMY. — An  interesting  series  of  articles  on  the 
use  of  high-frequency  electric  currents  for  the  production 
of  heat  in  the  body  of  a  patient  appears  in  recent  numbers  of 
the  Archives  of  the  Rontgen  Ray.  The  author  (Dr.  Cumber- 
batch)  is  in  charge  of  the  electrical  department  at  St.  Bar- 
tholomew's Hospital,  and  thus  the  information  may  be 
regarded  as  authoritative.  The  electric  current  provides 
a  unique  method  of  supplying  heat  to  the  deep  tissues 
of  the  body  ;  other  methods  of  heating  the  body  act  on 
the  skin.  When  high-frequency  current  is  employed 
no  pain  is  felt,  no  muscular  contraction  is  produced,  and 
no  sensation  other  than  warmth  is  perceived,  even  when  the 
current  reaches  the  root  mean  square  value  of  from  two  to 
three  amperes.  D'Arsonval  showed  in  1891  that  a  current 
of  three  amperes  could  be  passed  through  the  human  body 
with  impunity,  provided  that  the  frequency'  of  alternation 
was  great.  Currents  of  such  strength  had  not  been  used 
previously  in  electro-therapeutics  ;  and,  as  they  became 
better  known,  it  was  soon  evident  that  the  curative  effects 
wliich  followed  their  use  were  due  to  heat  ;  hence  the  term 
"  diathermy,"  to  distinguish  the  method  from  the  older 
ways  of  applj'ing  high-frequency  currents  in  medicine. 
The  apparatus  for  the  production  of  the  currents  used  in 
diathermy  consists  of  two  transformers,  the  first  to  raise 
the  alternating  current  from  the  mains  to  a  few  thousand 
volts.  The  secondai-y  current  from  this  first  transformer 
charges  a  condenser,  wliich  is  discharged  through  a  spark 
gap  and  through  the  primary  coil  of  the  second  transformer. 
The  oscillations  of  the  current  in  this  condenser  circuit 
have  a  frequency  of  the  order  of  a  million  a  second,  and 
produce  in  the  secondary  of  the  second  transformer  the 
current  (of  the  same  frequency),  which  is  passed  through 
the  patient.  The  design  of  the  apparatus  is  such  that  the 
current  which  heats  the  tissues  is,  as  measured  on  a  hot-wire 
ammeter,  adjustable  from  zero  up  to  two  or  three  amperes. 
The  spark  gap  is  of  a  very  special  construction.  It  has, 
in  one  form  of  the  apparatus,  a  double  gap,  each  a  quarter 
of  a  millimetre  in  length,  the  spark  occurring  between  the 
opposed  faces  of  polished  silver  plates.  The  sparks  take  the 
form  of  blue  films  that  occupy  the  air  space  between  the 
discs.  The  intervals  between  the  successive  trains  of  high- 
frequency  oscillations  are  very  small,  so  that  the  blue  film 
appears  to  be  continuous  to  the  eye  ;  the  discharge  is 
accompanied  by  a  hissing  sound.  The  diathermy  current 
is  led  to  the  electrodes,  which  are  in  contact  with  the 
patient  by  short,  well-insulated,  flexible  leads,  the  contacts 
mide  with  the  body  by  the  electrodes  being  moistened  with 


February,  1915. 


KNOWLEDGE. 


57 


salt  solution.  The  frequency  of  the  oscillations  is  not 
exceedingly  high ;  and,  since  the  resistance  of  the  tissues 
is  great,  the  current  is  not  confined  to  the  outer  parts  of 
the  conducting  tissues,  as  would  occur  \\-ith  better  con- 
ductors and  higher  frequency.  The  electrodes  and  currents 
can  be  arranged  so  as  to  cause  a  rise  of  temperature  of  a  few- 
degrees  only,  or  the  electrical  heating  may  be  concentrated 
on  a  portion  of  tissue  which  it  is  desired  to  coagulate  and 
destroy,  ^\^len  the  former  method  of  application  is  employed 
the  whole  body  is  heated,  and  the  skin  becomes  bathed  in 
sweat,  owing  to  the  convection  of  the  heat  by  the  blood. 
Some  interesting  experiments  are  described,  in  one  of  which 
albumen  is  coagulated  in  tlie  space  between  the  electrodes 
connected  to  the  diathermy  apparatus,  and  in  another 
a  cube  of  raw  meat  is  charred.  Two  disc  electrodes,  one 
inch  in  diameter,  are  placed  on  opposite  sides  of  the  cube. 
A  central  bridge  of  meat^is  soon  cooked,  and  is  finally 
charred. 

RADIO-ACTIVITY. 

By  Alexander  Fleck,  B.Sc. 

MEDICAL  USES  FOR  RADIUM.— Early  in  the  histon.' 
of  radio-acti\'it>'  it  was  disco\ered  that  the  rays  produced 
by  atomic  disintegration  had  some  effect  on  the  tissue  of 
organisms,  and  in  recent  years  many  in  the  medical  pro- 
fession have  turned  their  attention  to  directing  such  effects 
to  alleviate  and  cure  various  diseases.  In  some  forms  of 
disease,  such  as  rodent  ulcers,  a  cure  ma^'  be  confidently 
expected,  provided  that  sufficient  quantities  of  radium  are 
used.  In  other  and  more  serious  diseases,  as,  for  example, 
cancer,  it  is  not  yet  possible  to  say  that  a  complete  cure  can 
be  looked  for.  It  seems,  however,  that  the  malignancy 
of  the  disease  is  mitigated  by  the  application  of  radium,  and 
often  a  cure  lasting  for  a  number  of  years  has  been  obtained. 
-■Vlthough  the  disease  may  recur,  it  does  not  necessarily 
follow  that  it  will  do  so.  The  position  taken  up  by  the 
London  Radium  Institute  and  most  medical  men  is  that, 
whenever  the  cancer  is  at  all  operable,  an  excision  is  made, 
and  the  radium  treatment  reserved  for  inoperable  cases. 
Considerable  hope  is  entertained  that,  by  judicious  com- 
bination of  radium  treatment  and  e.xcision,  cancer  will 
soon  cease  to  be  the  terrible  scourge  that  it  is  at  present. 

London,  of  course,  has  had  for  some  years  now  a  large 
quantity  of  radium  available  for  medical  purposes,  and 
several  other  cities  in  the  United  Kingdom  have  recently 
purchased  quantities  to  be  set  aside  for  use  in  the  treatment 
of  disease. 

RADIO-ACTIVITY  AT  THE  BRITISH  ASSOCIATION. 
— In  the  issue  of  Nature  for  November  26th  a  report  is 
given  of  the  proceedings  of  Section  A  (Physical)  of  the 
meeting  in  Australia,  and  it  seems  that  pure  radio-activitj^ 
occupied  a  minor  position,  while  the  allied  subject  of  radi- 
ations in  general  was  discussed  in  a  number  of  important 
aspects.  From  the  point  of  view  of  the  radio-active  chemist, 
the  most  interesting  was  a  joint  discussion  with  the 
Chemistry  Section  on  the  structure  of  atoms  and  molecules. 
Professor  H.  E.  Armstrong  seems  to  have  been  the  chief 
representative  of  chemistry,  and  contributions  were  made 
by  Sir  E.  Rutherford,  Professor  Nicholson,  l\Ir.  IMoseley, 
and  others.  Professor  Hicks  dealt  with  the  subject  from 
the  spectroscopic  point  of  view,  and  stated  that  neither  by 
the  Thomson  nor  the  Rutherford  atom  is  it  easy  to  explain 
the  spectra  of  the  elements.  The  real  atom  seems  to 
be  something  more  complicated  than  either  of  these  models. 
The  meeting  is  said  to  have  been  more  of  a  s>Tnposium 
than  a  discussion ;  and,  while  no  new  facts  or  principles  of 
importance  have  been  enunciated,  the  full  report  which  it 
is  promised  will  be  published  in  the  annual  British 
Association  volume  will  be  awaited  with  interest. 

FORMATION  OF  ACTIVE  DEPOSITS.— Very  shortly 
after  the  discovery  of  radium  emanation  it  was  found  that 
if  two  metal  plates,  one  positively  and  the  other  negatively 
charged,  were  placed  for  a  few  hours  in  a  space  available 


to  this  gas,  the  negatively  charged  plate  became  intensely 
active,  whilst  the  positive  plate  had  only  a  very  small 
acti\-it5-.  The  material  that  produces  the  activities  so 
obtained  is  called  the  "  active  deposit." 

It  is  easily  proved  that  the  emanation  itself  is  not  affected 
by  the  electric  field,  and  that  therefore  it  is  electrically 
neutral.  The  emanation  in  its  disintegration  gives  oft 
an  a-particle,  carrj-ing  two  positive  unit  charges,  and  there- 
fore we  should  expect  that  the  remaining  part  of  the  ema- 
nation atom  (i.e.,  after  taking  away  positive  electricity  from 
a  neutral  body)  would  be  negatively  charged.  If  this  were  a 
complete  explanation  of  the  disintegration  of  the  ema- 
nation, then  the  active  deposit  material  would  be  attracted 
to  the  positive  plate  in  place  of  being,  as  it  actually  is, 
collected  on  the  negative  plate.  This  anomaty  is  explained 
by  the  Uberation  of  a  number  of  low-speed  negatively 
charged  5-rays  by  the  a-particle  in  its  passage  through  the 
atom.  There  remains,  however,  the  question  as  to  how  the 
small  quantity  of  active  deposit  is  obtained  on  the  positive 
plate,  and  tliis  problem  has  been  attacked  in  a  number  of 
papers  which  have  recently  appeared  in  the  Philosophical 
Magazine  (papers  by  WelUsch,  Walmsley,  and  Lucian). 
The  main  conclusion  in  aU  cases  is  the  same,  namely,  that 
when  the  A  member  of  the  active  deposit  (i.e.,  the  first 
disintegration  product  after  the  emanation)  is  formed,  it 
always  carries  a  positive  charge,  but  that,  just  as  in  the  case 
of  an  ordinar^^  gas  ion,  in  the  course  of  diffusion  it  may 
recombine  with  another  negative  ion  to  become  electrically 
neutral.  \Mien  this  happens  this  neutral  particle  will  be 
deposited  on  the  first  surface  that  it  meets.  The  small 
quantity  of  active  deposit  material  referred  to  is  therefore 
obtained  from  those  particles  rendered  neutral  by  re- 
combination which  have  chanced  to  come  into  contact  with 
the  positively  charged  surface. 

SEPARATION  AND  PURIFICATION  OF  RADIUM. 
— In  a  uranium-bearing  mineral  the  greatest  possible  amount 
of  radium  (except  in  very  rare  circumstances)  that  may  be 
present  is  3-23  parts  of  radium  for  every  ten  million  parts 
of  uranium,  and  the  task  of  separating  this  very  small 
amount  of  material  is  one  that  demands  a  considerable 
amount  of  chemical  skill.  As  it  is  first  separated,  the  radium 
is  contained  in  a  mixture  of  barium,  lead,  and  other  sub- 
stances, of  which  the  sulphate  is  comparatively  insoluble. 
The  concentration  at  this  stage  is  usually  about  0-2  to  0-5 
of  a  milligramme  of  radium  per  kilograrmne  of  material. 
This  sulphate  has  then  to  be  converted  into  some  soluble 
salt,  usually  the  chloride,  sulphuretted  hydrogen,  and  then 
ammonia  added  to  the  solution  so  obtained  in  order  to 
remove  elements  of  the  lead  and  iron  groups  respectively. 
Finally,  the  radium  is  obtained  in  the  filtiate  from  these 
elements  along  with  the  barium.  At  this  stage  the  pro- 
cedure is  transferred  from  the  works  to  a  chemical  laboratory, 
and  the  long  process  of  fractionation  is  commenced.  This 
consists  in  making  a  hot  concentrated  solution  of  the 
barium-radium  chlorides,  which  is  allowed  to  cool.  It  is 
found  that  the  crj'stals  that  separate  out  are  richer  in 
radium  than  the  material  that  remains  in  solution  (usually 
in  the  ratio  of  5  to  1).  This  process  is  repeated  a  great 
many  times  until  finally  pure  radium  is  obtained.  The 
physical  chemistry  of  the  process  is  verj'  interesting,  because 
it  IS  usually  taught  that  by  crj'stalUsing  a  substance  from 
solution  a  small  quantity  of  impurity  will  remain  in  the 
liquid,  and  that  the  crj'stals  will  be  pure.  In  the  above  case 
the  exceptionally  small  quantities  of  radium  present  are 
concentrated  in  the  crystals.  It  is  found  by  experience 
that  lead  also  accumulates  in  the  crystals,  and  it  has  to 
be  separated  frequently  by  sulphuretted  hydrogen  or  some 
other  means. 

In  some  Austialian  works  this  process  is  considerably 
modified,  and  an  account  was  given  during  the  course  of 
last  year  by  Radcliff  to  the  Sydney  Section  of  the  Society 
of  Chemical  Industry',  in  which  pure  barium-radium 
chloride  was  obtained  by  saturating  the  solution  obtained 
from  the  crude  sulphates  with  hydrochloric-acid  gas. 


58 


KNOWLEDGE. 


Februarv,  1915 


ZOOLOGY. 

By  Professor  J.  Arthur  Thomson,  M.A.,  LL.D. 

CATERPILLARS'  SETAE.— It  appears  that  the  de- 
scription of  "  aerostatic  hairs  "  on  the  caterpillars  of  the 
Gipsy  Moth  and  Nun  Moth  was  mistaken.  The  globular 
swellings  at  the  bases  of  the  hairs  were  supposed  to  be  air 
reservoirs,  facilitating  dispersal  by  the  wind.  Riley  showed 
some  time  ago  that  the  swelling  does  not  contain  air,  but 
fluid,  and  that  there  is  a  large  glandular  cell  opening  into 
it.  It  is  probable  that  the  fluid  is  poisonous,  and  protective 
against  insectivorous  birds. 

FORMER  CONNECTIONS  OF  ANTARCTIC  CON- 
TINENT.—In  giving  an  account  of  the  fishes  collected  by 
the  British  Antarctic  ("  Terra  Nova  ")  Expedition,  1910, 
Mr.  C.  Tate  Regan,  of  the  British  Museum,  has  taken 
occasion  to  examine  the  evidence  in  support  of  the  \'ie\v 
held  by  many  authorities  that  in  the  Early  Tertiary  the 
Antarctic  Continent  was  connected  with  Australia  and  with 
South  America.  He  comes  very  definitely  to  the  conclusion 
that  neither  the  freshwater  fishes  nor  the  marine  fishes, 
whether  Antarctic  or  South  Temperate,  support  the  theory 
that  Antarctica  has  connected  Australia  with  South 
America  in  Tertiary  times.  The  evidence  from  other 
groups  of  animals  seems  to  Mr.  Regan  to  confirm  the  con- 
clusion which  he  reached  from  his  study  of  the  fishes. 

SHORE  MITES.— Professor  L.  A.  L.  King's  recent 
observations  on  some  littoral  mites  on  the  shore  near  Millport 
Biological  Station  show  how  much  interesting  material  is 
available  to  keen  eyes.  Thus,  as  to  the  feeding  of  Gamasiis 
[Eugamasus)  immanis,  it  is  noted  that  the  mite  plunges  its 
chelate  chelicerae  into  the  body  of  living  Oligochaetes, 
tears  out  a  piece,  and  sucks  it  dry.  As  Michael  showed,  the 
male  inserts  his  mandibles  into  the  genital  opening  of  the 
female,  and  empties  the  contents  of  a  spermatic  capsule 
into  the  vagina.  Of  Gamasiis  (Halolaelaps)  glabyiusculus  it 
is  noted  that  it  survived  complete  immersion  in  water  for 
forty-eight  hours.  The  large  red  Bdellid  (Mo/giis  Uttoralis) 
was  seen  feeding  on  a  small  living  Dipteron.  The  smaller, 
more  vivid,  more  gregarious  Bdella  longicornis  probably 
feeds  on  the  Collembolan  Antirida  maritima,  common  on 
the  shore.  This  species  of  Bdella,  as  Mr.  T.  J.  Evans,  of 
Sheffield,  has  also  noticed,  spins  a  silken  tent  in  autumn. 

NUMBERING  HAIRS.— Evidence  of  the  definiteness  of 
indi\'idualit5'  is  always  interesting.  We  know  of  some 
simple  animals  which  have  always,  or  almost  alwa^'s,  the 
same  number  of  cells  in  particular  parts  of  their  body, 
and  in  their  body  as  a  whole,  and  Mr.  Phineas  W.  Wliiting 
has  shown  the  same  sort  of  specificity  in  the  bristles  on  the 
back  of  the  Green-bottle  Fly  (Lucilia  sericata).  He  studied 
a  group  of  twelve  dorsal  bristles,  and  found  that  the  number 
is  hereditary  and  the  distribution  hkewise.  There  may  be  a 
few  less  or  more,  but  only  a  few.  Reduction  rarely  goes 
beyond  the  loss  of  two  bristles  in  a  single  fly.  Out  of  five 
thousand  three  hundred  and  sixty-seven  flies  bred,  there  was 
a  reduction  of  748'5  in  the  males  and  of  455-5  bristles  in  the 
almost  equal  number  of  females.  There  were  two  hundred 
and  ten  bristles  added  in  the  males,  and  three  hundred  and 
forty-three  added  in  the  females. 

FREQUENCY  OF  PARASITES  IN  FISHES.— The 
clean  and  wholesome  nature  of  the  flesh  of  fishes  is  well 
known.  Its  relative  freedom  from  parasites  is  noteworthy 
and  of  practical  importance.  But  the  number  of  parasitic 
worms  found  in  the  intestines,  and  in  other  parts  of  the  food- 
canal,  is  enormous.  Dr.  W.  Nicoll,  one  of  the  foremost 
helmintliologists,  has  examined  eight  hundred  and  forty-five 
fishes  (one  hundred  and  two  different  kinds)  from  around  our 
coasts,  and  has  found  eighty-one  per  cent,  with  parasites 
(of  over  fifty  different  kinds).  Of  four  hundred  and  seventy- 
five  fishes  from  Plymouth,  three  hundred  and  eighty  (eighty 
per  cent.)  were  infected  :  fifty-six  per  cent,  with  flukes, 
forty-four  per  cent,  with  tapeworms,  forty-eight  per  cent. 


with  tlireadworms,  and  two  per  cent,  wth  Echinorhynchs. 
Millport  fishes  yielded  the  same  percentage,  St.  Andrews 
fishes  eighty-three  per  cent.,  and  Aberdeen  fishes  ninety-one 
per  cent.  This  large  incidence  of  parasites  is  remarkable  : 
it  throws  some  li,ght  on  the  stern  character  of  the  struggle 
for  existence.  In  most  cases,  probably,  the  parasites  do 
little  harm  unless  they  reach  a  host  unaccustomed  to  them. 

THE  MAN-OF-WAR  INFUSORIAN— A  glimpse  into 
the  intricacy  of  things  is  afforded  by  E.  Penard's  description 
of  a  ciliated  Infusorian,  which  he  found  in  a  marsh  near 
Genev;i,  and  names  Legendrea  bellerophoyt.  The  genus  was 
established  by  Faur^-Fremiet,  but  the  species,  bellerophon, 
which  we  have  translated  "  man-of-war,"  is  new.  It  is 
from  120-180^  in  length,  and  about  a  third  as  broad  : 
it  has  a  slit-like  mouth,  a  horse-shoe-shaped  nucleus,  a  large 
contractile  vesicle,  and  many  other  features  with  which 
we  are  familiar  in  ciliated  Tnfusorians.  But  the  remarkable 
feature  is  that  on  each  side  of  the  somewhat  man-of-war- 
shaped  creature  there  project  about  ten  papillae  at  regular 
intervals,  like  the  guns  from  a  frigate.  Each  of  these 
papillae  bears  at  its  blunt  extremity  a  group  of  stinging 
threads,  or  trichocysts,  from  which,  again,  very  delicate, 
probably  poisonous  filaments  can  be  protruded.  Each 
papilla  is  like  a  mitrailleuse,  and  a  very  effective  weapon. 
There  are  trichocysts  on  other  parts  of  the  Infusorian, 
but  they  explode  only  on  the  projecting  papillae.  In  a  very 
striking  way  they  move  or  are  moved  to  the  bases  of  the 
papillae,  and  accumulate  there,  "  waiting  their  turn  " 
to  pass  up,  or  to  be  passed  up,  to  the  tips  of  the  papillae. 
When  the  delicate  filament  is  protruded  from  the  exploded 
trichocyst  a  minute  viscous  drop  of  poison  appears  at  its 
ruptured  end.  The  well-armed  Infusorian  swims  slowly, 
and  is  carnivorous.  It  is  wont  to  attack  a  minute  Rotifer 
called  Diplax  lyigona. 

ANIMAL  HYPNOSIS.— When  a  Snake  becomes  a  stick, 
or  a  Hen  lies  immobile  on  the  floor  with  a  chalk  line  in  front 
of  its  eyes,  or  a  Crayfish  stands  on  its  head,  or  a  Ground- 
beetle  (such  as  Scarites  buparius)  feigns  death  on  being 
shaken,  we  have  to  deal  with  animal  hypnosis.  In  a  recent 
investigation  Professor  Mangold  defends  the  position  that 
animal  hypnosis  is  analogous  with  human  hypnosis,  and 
on  the  physiological  side  the  resemblance  is  certainly  close. 
Mangold's  definition  of  animal  hypnosis  is  as  follows  : 
A  reflex  tonic  inhibition  of  locomotion  and  position-adjust- 
ment, induced  by  a  sum  of  afferent  stimuli,  resulting  in  a 
sleep-like  state  in  which  there  may  be  great  changes  in 
muscular  tonus  (first  increase,  and  then  decrease)  and 
decrease  of  sensitiveness  to  many  kinds  of  stimulus,  e.g.,  of 
a  painful  sort.  One  of  the  many  difficulties  concerning 
animal  hypnosis  is  its  relative  uselessness.  It  may  perhaps 
be  of  service  when  a  ground-bird,  hotly  pursued,  squats 
motionless,  or  when  a  mammal  "  plays  'possum  "  ;  but  even 
this  has  not  been  proved  to  be  "  hypnosis  "  in  the  strict 
sense,  and  in  most  cases  among  backboned  animals  the 
capacity  is  known  only  in  the  laboratory.  Among  Arthro- 
pods it  is  of  great  service  in  stick-insects,  wliich  pass  into 
hypnosis  under  the  stimulus  of  light,  and  simulate  in  their 
pose  the  twigs  which  thev  resemble  in  colour  and  shape. 
But  in  many  cases  the  hypnotic  state  is  readily  assumed  under 
various  stimuli  without  any  resulting  utility  being  ob\ious. 
Very  interesting  is  1he  case  of  the  female  Galeodes — a  fierce 
and  unapproachable  creature — wiiich  passes  into  hypnosis 
when  suddenly  seized  by  the  smaller  and  weaker  male. 
It  looks  as  if  we  had  to  do  with  a  widespread  capacity 
which  persists  as  a  concomitant  of  an  effective  nervous 
constitution,  but  is  only  now  and  again  itself  brought 
within  the  sphere  of  utility. 

ADAPTATIONS  OF  THE  PLANKTON.— Professor 
J.  Graham  Kerr  discussed  in  a  recent  lecture  the 
adaptations  of  the  drifting  animals  of  the  sea.  Macro- 
plankton  animals,  illustrated  by  jelly-fishes,  pelagic  anneUds, 
like  Tomopteris,  and  Salps,  often  show  transparency,  or 
some  coloration,  which  is  a  garment  of  invisibility.      In  the 


February,  1915. 


KNOWLEDGE. 


59 


Leptocephalus  stage  of  the  Eel  the  haemoglobin  of  the  blood 
is  actually  suppressed.  (It  is  noted,  in  passing,  that  red 
prawns  from  the  deep  dark  waters  are  not  "  red  "  in  their 
ordinary-  habitat,  but  simply  dark.  No  red  rays  of  light 
penetrate  through  the  upper  fiftj'  fathoms,  and  an  object 
cannot  look  red  unless  red  raj'S  of  light  are  falling  upon  it.) 
Jlany  of  the  macroplankton  animals  are  phosphorescent, 
and  the  pattern  of  the  Ughts  may  sometimes  help  in  recog- 
nition. Sense-organs,  e.g.,  balancing  organs,  are  well 
developed.  Flotation  is  assisted  in  many  ways,  e.g.,  by  the 
gas  in  the  internal  shell  of  Sepia,  or  by  the  s^\^m-bladder  of 
fishes.  Part  of  the  lining  of  the  swm-bladder  can  secrete 
oxygen,  and  another  part  can  absorb  the  gas ;  thus  increasing 
or  decreasing,  as  occasion  demands,  the  internal  pressure. 
Thus  the  fish  is  able  to  float  at  one  level  without  effort. 

In  the  microplankton,  such  as  Radiolarians  and  Copepods, 
the  problem  of  flotation  may  be  solved  by  lessening  the 
specific  gravity'  of  the  animal,  e.g.,  by  accumulating  gela- 
tinous material  in  jelly-fishes.  Or  there  may  be  arrange- 
ments for  gi\"ing  increased  effect  to  the  \■^scosit^'  of  the  sea- 
water.  This  may  be  brought  about  merely  by  diminution 
in  the  size  of  the  creature,  the  ratio  of  surface  to  volume 
increasing  with  diminution  of  bulk,  or  by  the  development 
of  spinj-  or  feathery  outgrowths.  The  \'iscosity  is  lessened 
with  rise  of  temperature,  and  thus  the  arrangements  just 
alluded  to  are  especially  well  marked  in  the  plankton  of  the 
warmer  seas. 

SEX  RECOGXITIOX  IX  WOOD  FROG.— Arthur  M. 
Banta  {Biological  Bulletin,  Volume  XXVI)  has  tried  to 
discover  the  method  of  sex  recognition  in  Rana  svlvatica, 
the  wood  frog.  The  males  distinguish  the  females  (from 
other  males)  at  a  short  distance.  There  may  be  something 
in  the  diSerences  of  the  sexes  in  swimming  and  in  beha\-iour 
when  approached,  and  possibly  something  in  the  diSerences 
in  colour.  But  dead  females  are  distinguished  from  dead 
males,  and  it  is  suggested  that  a  chemical  sense  in  involved. 
This  should  be  made  a  subject  of  experiment.  The  males 
test  ever^^  frog  or  mo\-ing  object  within  a  radius  of  severed 
feet,  and  their  cold-blooded  ardour  leads  to  a  good  deal  of 
fatal  "  disharmony." 


SHORE  FAUNAS. — Professor  A.  S.  Pearse  distinguishes, 
at  Nahant,  ]Massachusetts,  the  rock  beach,  the  sand  beach, 
and  the  mud  flats.  The  mud  flats  are  marked  by  the  lack 
of  suitable  objects  for  attachment  (therefore  no  sponges, 
hydroids,  and  so  on),  and  bj-  the  comparative  impurity  of 
the  water  (therefore  adaptations  for  respiration,  as  in  Mya, 
with  its  long  siphon).  The  fauna  of  the  sand  beach  is  com- 
posed largely  of  burrowing  animals  and  those  which  are 
continually  being  swept  in.  The  rock  beach  is  divided  into  : 
(1)  the  rocks  above  high-tide  mark  ;  (2)  the  Bala  mis  zone  ; 
(3)  the  Ascophyllum  zone,  with  Serlularia  pumila,  anemones, 
Purpura,  'Littorina,  and  so  on  ;  (4)  the  Fucus  zone,  with 
M\ttlus,  Balanus,  Acmaea,  Purpura,  Littorina,  Asterias, 
and  so  on  ;  and  (5)  the  Chondrus  zone,  most  thicklj' 
peopled,  with  Idothea,  Acmaea,  Asterias,  Cancer,  Meiridium, 
and  various  Bryozoa. 

"  Probabl}-  no  other  animal  habitat  is  subject  to  such  a 
wide  range  of  fluctuations  in  environmental  conditions 
as  the  rock  beaches  along  the  ocean.  The  flora  and  fauna 
must  endure  the  frigid  span  of  winter  and  the  blistering 
sun  of  summer.  There  is  no  escape  :  the  tide  keeps  up  its 
eternal  rh}-thm,  and  the  organisms  are  left  exposed  to  the 
elements  everv  time  the  water  recedes.  The  exposure  of 
the  hard  substratum  to  sun,  wind,  and  wave  has  developed 
a  fauna  which  consists  largely  of  animals  that  are  :  (1) 
attached  permanently  or  have  well-developed  clinging 
organs ;  (2)  active  and  hard-shelled  or  (3)  small  and 
ubiquitous  ;  and  (4)  mostly  very  hardy,  and  able  to  stand 
considerable  exposure."  The  animals  that  have  these  cha- 
racteristics most  developed  have  the  widest  distribution. 

"  The  surface  of  the  rock  is  a  veritable  sieve  through 
which  the  microscopic  organic  content  of  the  water  dis- 
appears. The  barnacles  sweep  it  constantly  with  their 
fishing  nets  :  the  carpets  of  clams  siphon  food  into  their 
depths  from  the  turbid  water ;  Littorinas  search  ever\- 
square  inch,  and  sweep  it  clean  ;  wherever  there  is  sufficient 
moisture  the  Coelenterates  and  Brj'ozoans  spread  their 
deUcate  tentacles  to  seize  their  share."  There  is  keen  com- 
petition for  food  and  foothold ;  it  is  a  crowded  battle- 
ground ;  it  has  been  a  great  school.  It  is  interesting  to 
compare  Pearse 's  survey  at  Nahant  with  that  made  by 
Russell  and  Iving  at  Millport,  on  the  Clyde. 


REVIEWS. 


BOTANY. 


Practical    Field    Botany. — By    A.     R.    Horwood,     F.L.S. 
193  pages.     22  plates.     26  figures.     8-in.  x  5-in. 

(Charles  Griffin  &  Co.     Price  5  /-  net.) 

Mr.  Horwood  is  doing  a  great  deal  to  popularise  the  study 
of  botany  and  to  direct  those  who  take  it  up  into  the  right 
way.  At  the  same  time,  his  energies  are  being  devoted 
to  preserving,  so  far  as  is  possible,  our  native  flora  from 
undue  diminution  or  extermination.  The  present  book 
will  cater  for  those  who  are  led  to  study  plants  through  the 
now  far-reaching  nature-study  movement.  It  deals  with 
the  scope,  object,  and  aims  of  botany  ;  it  describes  the 
various  methods  o'  raountincr  plants  ;  it  touche.s  on  wild 
flower  tables,  on  museums  which  are  stationary  and  peri- 
patetic. It  shows  what  is  being  done  to  encourage  the 
study  of  botany  ;  and,  after  dealing  with  the  Ufe-history 
of  a  plant,  occupies  itself  with  ecologj-,  or  the  association 
of  plants  together  into  what  the  author  calls  "  formations  ' 
according  to  soil  and  situation.  This  is  the  kind  of  botany 
which  appeals  most  strongly  to  the  general  lover  of  nature, 
and  broadens  the  outlook  of  the  systematic  botanist. 
No  one  who  reads  Mr.  Horwood's  book  can  fail  to  find  some 
suggestion  of  use  and  of  interest.  We  heartily  wish  the 
work  the  success  which  it  deserves,  and  commend  it  specially 
to  the  notice  of  nature-study  teachers. 

\V.  M.  W. 


CHEMISTRY. 

Essays    and    Addresses. — By    the    late    J.\mes    Campbell 

Brown,  D.Sc.     208    pages.     23  illustrations.     SJ-in.   by 

5f-in. 

(J.  &  A.  Churchill.     Price  5/- net.) 

The  work  of  Dr.  Campbell  Brown  included  both  the  aca- 
demic and  the  professional  side  of  chemistrj' ;  for,  in  addition 
to  holding  the  chair  of  chemistry-  in  the  Liverpool  Univer- 
sity, he  was  also  a  public  analyst  and  a  consulting  chemist. 
The  practical  aspect  of  his  work  is  reflected  in  the  whole 
of  these  essa^-s  and  addresses,  which  are  for  the  most  part 
of  a  utihtarian  character.  They  include  addresses  to  the 
Society  of  Chemical  Industry-  on  such  subjects  as  "  Technical 
Chemistry-  "  and  the  "  Ethics  of  Chemical  Manufacture  "  ; 
biographical  sketches  of  great  chemists  ;  and  historical 
papers,  such  as  "  Chemistry  in  Liverpool  in  1801." 

All  of  these  papers  are  ver\-  readable,  even  by  those  with- 
out any  knowiedge  of  chemistry,  especially  the  last  two 
on  "  .\nalytical  Chemistry'  as  a  Profession  "  and  "  Science 
Applied  to  the  Detection  of  Crime,"  which  are  characterised 
by  their  sound  common  sense  and  keen  humour. 

Some  of  the  opinions,  however,  are  open  to  criticism. 
For  example,  it  seems  to  us  that  there  is  some  justification 
for  the  pubUc  attitude  towards  mistakes  made  by  an 
analj-st,  against  which  Dr.  Brown  protests  in  several 
places  ;  as,  for  instance,  on  page  202  :  "  The  public  can- 
not forgive  a  mistake  in  an  analyst.  A  doctor  makes  a 
mistake,  and  buries  it.    A  lavvyer  makes  a  mistake,  and  is 


60 


KNOWLEDGE. 


February,  1915. 


paid  for  it  as  highly  as  if  he  had  not.  A  clergyman  makes  a 
mistake,  and  it  is  discovered  only  in  the  ne.xt  world.  But 
if  an  analyst  makes  a  mistake,  he  is  condemned.  He  has 
committed  the  unpardonable  sin." 

The  difference  between  the  analyst  and  the  other  pro- 
fessional inen  cited  is  that  he  makes  assertions  as  to  matters 
of  fact,  whereas  the  physician,  lawyer,  and  clergymen  may 
express  opinions.  If  the  analyst  can  be  shown  to  be  wrong, 
this  mistake  is  regarded  by  the  public  as  of  the  same  kind 
as  that  of  the  dentist  who  pulls  out  the  wrong  tooth,  or 
the  surgeon  who  makes  a  cut  in  the  wrong  place.  In  both 
of  these  instances  a  court  would  award  damages  to  the 
victim. 

C.  A.  M. 

Tlie  Elements  of  Chemistry. — By  H.  L.  Bassett,  B.A.,  B.Sc. 
With  an  introduction  by  Professor  W.  J.  Pope,  M.A., 
F.R.S.     368  pages.     32  illustrations.     7-in.  x  5-in. 

(Crosby  Lockwood  &  Son.     Price  4/6.) 

Professor  Pope  points  out  very  cogently  in  his  intro- 
duction that  most  scientific  professions  demand  some  ele- 
mentary knowledge  of  chemistry  in  more  than  one  of  its 
divisions,  although  a  student's  work  may  subsequently  have 
only  an  indirect  connection  with  the  science.  It  is  with  the 
needs  of  the  medical  student  more  especially  in  view  that  this 
book  has  been  written,  and  it  should  pro\-e  of  the  greatest 
ser\dce  to  those  who  are  preparing  for  the  examinations 
of  the  Conjoint  Board.  It  is  divided  into  the  four  sections  : 
General  and  Physical  Chemistry,  Inorganic  Chemistry, 
Organic  Chemistry,  and  Practical  Chemistry.  Obviously 
it  is  impossible  within  so  limited  a  space  to  go  very  tho- 
roughly into  any  of  these  branches,  but  the  book  gives  a 
useful  summary,  and  for  those  who  are  not  working  for 
examinations  it  could  well  serve  as  an  inti'oduction  to  larger 
treatises.  It  would  be  an  advantage,  from  one  point  of 
view,  if  the  practical  work  were  distributed  throughout  the 
other  sections,  instead  of  being  put  at  the  end  of  the  book. 
The  theory  of  chemistry  should  be  supported,  not  crowned, 
by  experimental  work. 

C.  A.  M. 

The  Chemistry  of  the  Radio-Elements  (Part  I). — By  Frederick 
SoDDY,  F.R.S.     151  pages.     3  figures.     8|-in.  x  5|-in. 

(Longmans,  Green  &  Co.     Price  4  .'-  net.) 

Part  II  of  this  book  was  issued  in  1914,  as  a  result  of 
important  advances  then  made  ;  to  supply  the  demand 
consequent  on  the  interest  created  in  the  subject  by  those 
advances,  it  has  been  necessary  to  publish  a  new  edition 
of  Part  I.  The  new  edition  has  not  only  been  brought  up 
to  date,  but  has  been  enlarged,  and  almost  completelv 
rewritten.  The  fact  that  this  new  edition  of  Part  I  has 
been  called  for  is  testimony  that  the  scientific  public  has 
realised  to  a  great  measure  the  advances  that  were  outlined 
in  Part  II. 

The  book  may  be  roughly  divide:!  into  two  halves,  the 
first  of  which  deals  with  the  general  principles  invol\-ed. 
In  the  latter  half  the  chemistry  of  the  radio-elements  is 
described  sj'stematically.  With  regard  to  the  first  half, 
we  feel  sure  that,  to  any  reader  who  wishes  to  become 
acquainted  with  the  broad  facts  and  principles  of  radio- 
activity from  the  physical  as  well  as  the  chemical  stand- 
point, no  better  summary  could  be  recommended,  provided 
that  he  possesses  a  knowledge  of  chemical  laws  and  of  the 
elementary  facts  of  general  science.  The  second  half  of  the 
book  will  be  of  greater  use  to  the  person  engaged  practically 
in  radio-active  work,  and  the  author's  great  experience 
in  this  direction  has  enabled  him  to  make  this  section  of 
the  greatest  value  for  use  in  the  laboratory. 

The  chapter  on  the  "  Adsorption,  Electro-,  and  CoUoido- 
Chemistry  of  the  Radio-Elements  "  is  exceptionally  interest- 
ing, and  contains  a  number  of  suggestions  for  further 
work. 

A.  F. 


EVOLUTION. 

Mutual  Aid  :    A  Factor  of  Evolution. — By  P.  Kropotkin. 
Popular  Edition.     240  pages.     7i-in.  x  5-in. 

(William  Heinemann.     Price  1  /-  net.) 

The  issue  of  a  cheap  popular  edition  of  Prince  Kropotkin's 
well-known  book,  "  Mutual  Aid,"  is  particularly  to  the 
point  at  the  present  moment.  It  has  been  suggested  that 
the  wholesale  destruction  of  life  among  non-combatants 
and  the  pillage  of  their  means  of  subsistence  in  the  present 
war  is  part  of  the  ordinary  "  struggle  for  the  existence." 
Prince  Kropotkin's  book,  dealing  as  it  does  with  mutual 
aid  amongst  human  beings,  supports  the  protest  which  has 
been  made  against  such  an  abuse  of  Darwin's  terminology. 

For  those  who  are  unfamiliar  with  "  Mutual  Aid  "  we  may 
add  that  it  describes  co-operation  among  animals,  among 
savages  and  barbarians,  and  with  the  craft  guilds  of  the 
mediaeval  city,  in  addition  to  more  modern  instances. 

W.  M.  W. 

FARMING. 

Impurities  of  Agricultural  Seed,  with  a  Description  of  com- 
monly occurring  Weed  Seeds  and  a  Guide  to  their  Idoitification. 
— By    S.    T.     Parkinson,     B.Sc,    and    G.    Smith,     B.Sc. 
105  pages.     152  illustrations.     7|-in.  x5-in. 

(Headley  Brothers.     Price  3  /-  net.) 

In  few  walks  of  life  is  the  necessity  for  organised  know- 
ledge at  the  present  time  greater  than  in  farming.  The 
agriculturist  has  learnt,  or  is  beginning  to  learn,  that  in 
the  case  of  many  plant  diseases  there  is  no  cure,  and  that 
he  must  rely  entirely  upon  prevention.  Though  weeds 
can  be  got  rid  of,  the  task  is  often  a  difficult  one,  and  here 
it  is  possible  to  avoid  one  common  cause  of  their  intro- 
duction. This  is  by  taking  care  not  to  sow  seed  which  is 
impure.  Before,  however,  a  farmer  can  tell  what  weed- 
seeds  occur  among  those  which  he  is  buying,  he  must  have 
some  knowledge  of  the  subject.  Messrs.  Parkinson  and 
Smith  are  therefore  to  be  congratulated  warmly  on  having 
produced  a  veiy  useful  book.  The  introduction  is  very 
concisely  and  simply  written,  while  the  large  number  of 
reproductions  of  photographs  of  weed-seeds,  of  which  we 
are  courteously  permitted  to  reproduce  a  few  in  Figures 
50  to  58,  will  be  a  very  great  help,  not  only  to  the  farmer, 
but  to  the  seed  specialist.  There  are  one  hundred  and  fifty- 
two  of  them  in  all,  and  each  is  accompanied  by  a  brief 
description  giving  the  size  of  the  seed  in  fractions  of  an 
inch  and   in  millimetres. 

W.  M.  W. 

GEOLOGY. 

Engineering   Geology. — By    H.    Ries   and   T.    L.    Watson. 
672  pages.     104  plates.     225  figures.     9-in.  x  6-in. 

(J.  Wilev  &  Sons,  New  York  ;  Chapman  &  Hall,  London. 
Price  17/-  net.) 

Geological  conditions  affect  many  engineering  operations, 
especially  in  railway  construction,  tunnel  driving,  reservoir 
building,  and  works  for  the  prevention  of  coast  erosion, 
improvement  of  rivers,  and  water  supply.  Geological  con- 
siderations also  affect  the  selection  of  building  stones,  road 
metals,  cement  materials,  and  clays,  as  well  as  the  materials 
such  as  coals  and  ore  deposits,  the  mining  of  which  has  long 
been  recognised  to  have  a  geological  basis.  There  has  long 
been  a  need  for  a  work  dealing  with  geology  from  this 
practical  point  of  view  in  its  relation  to  various  phases  of 
industrial  activity.  The  book  under  review  suppUes 
this  need  very  satisfactorily.  The  authors  throughout 
emphasise  the  practical  application  to  engineering  of  all  the 
topics  treated.  The  book  is  intended  primarily  for  civil 
engineers,  but  it  will  be  found  of  considerable  value  to  others 
interested  in  applied  geology. 

The  first  three  chapters  deal  compactly  but  quite 
effectively  with  the  mineralogy  and  petrology  necessary  to 
complete  comprehension  of  the  subject.  They  are  followed 
by   chapters   deahng   with   structural   features   and   meta- 


February.  1915. 


KNOWLEDGE. 


61 


tt  # 


Figure  50.     Charlock, 
{Brassica  siiiapis.f      X   10. 


Figure  51.     Hare's  Ear. 

(Bupleurum  rotitiidifoliiiDi. 

X   10. 


m 


Figure  52.     Yellow  Rattle, 
(Rhinanthiis  Cristagalli.)     X  4. 


Figure  53.    Wild  Radish,  Runch, 
(RapJumiis  raphaiiistniiii.)   X  4. 


Figure  54.     0.\-tongue, 
{Hclminthia  echioides.)      X  10. 


IK 


> 


Figure  55.     Cat-mint,  Cat-nip, 
iNepeta  Cataria.)      X  10. 


»■, 


» 


*g^-_-^- 


i?,V-: 


Figure  56.     White  Campion, 
{Lychnis  alba.)      X  10. 


99 


Figure  57.  Ivj'-leaved  Speedwell, 
{Veronica  hederaefolia.)      X  4. 


^        ''•^ 


Figure  58.     Curled  Dock, 
(Rtiinex  crispits.)      X  10. 


THE     SEEDS     OF     COMMO.NLV     OCCURRING     WEEDS. 
(From  ■'  Impurities  of  Agricultural  Seed,"  by  S.  T.  Parkinson  and  G.  Smith.       By  the  courtesy  of  Messrs.  Headley  Brothers.) 


62 


KNOWLEDGE. 


February.  1915. 


From  a  /.hotografh  h  Alfred  E.    Tongc,  F.E.S. 

Figure  59. 
Six-belted  Clearwing   5   on  flower  of  thrift.     iSesiii  iclnu'iiiiioiii/onnis.) 

Natural  size. 


By  the  courtesy  of   Wild  Life. 


Febri-arv.  1915. 


KNOWLEDGE. 


63 


inorpMsm  of  rocks,  and  with  rock  weathering  and  soils. 
Chapters  V  to  X  deal  more  directly  with  the  practical 
aspects  of  geology  in  relation  to  surface  and  underground 
waters,  land  sUdes,  waves  and  shore  currents,  lakes  and 
glacial  deposits.  The  remaining  chapters  demonstrate  the 
importance  of  geological  principles  in  the  winning  and 
selection  of  building  stones,  hmes,  cements,  plasters,  clays, 
coals,  petroleum,  road  metals,  and  ore  deposits. 

The  book  is  illustrated  with  one  hundred  and  four  excel- 
lently selected  and  well-executed  plates  and  tvvo  hundred 
and  twenty-five  figures,  some  of  which  are  open  to  criticism. 
Thus  Figure  73,  which,  according  to  the  designation,  is 
intended  to  show  monoclinal  attitude  of  strata,  shows  simple 
dip,  and  is,  moreover,  not  referred  to  in  the  text.  In 
Figure  74  the  shading  does  not  correspond  in  the  t^vo 
drawngs.  The  plan  and  section  do  not  correspond  in 
Figure  116,  whilst  in  Figure  64  there  is  an  extraordinary 
lack  of  deformation  in  the  strata  adjacent  to  a  broad 
fault-breccia  zone. 

Since  the  book  has  been  written  for  the  .\merican  student, 
we  can  hardly  be  surprised  that  American  examples  abound 
in  the  text,  and  that  Anierican  literature  is  mainly  cited  in  the 
concise  lists  of  literature  at  the  end  of  each  chapter.  Never- 
theless, the  plan  of  the  book  is  so  good  that  European 
engineers  will  find  its  methods  and  principles  adapted  to 
all  their  problems,  although  it  is  to  be  hoped  that  this  book 
will  stimulate  some  worker  wdth  the  necessary  quaUfications 
of  engineer  and  geologist  to  summarise  the  extensive  but 
scattered  British  Uterature  on  the  same  subjects. 

G.  W.  T. 
MATHEMATICS. 

A    First  Course   in  Mathematics  for  Technical  Students. — 

By    P.     J.    Hales    and    A.     H.     Stuart.        125     pages. 

7|-in.x5-in. 

(University  Tutorial  Press.     Price  1  /6.) 

The  material  in  this  little  book  is  practical  and  much 
condensed.  It  will  probably  be  found  useful  to  the  type 
of  student  for  which  it  is  intended.  The  explanations 
seem  to  be  full  in  some  cases  and  meagre  in  others  ;  but 
those  who  have  had  experience  in  practical  work  with 
artisan  students  must  know  that  their  difficulties  are  not 
the  same  as  those  of  the  ordinary  schoolbov. 

W.  D.  E. 

Elementary  Mathematical   Analysis. — B}'  C.    S.    Slighter. 
490  pages.     7i-in.  x  5  J-in. 

(Hill  Publishing  Company.     Price  10/6  net.) 

A  textbook  in  which  efficiency  (in  Lord  Rosebery's  sense) 
appears  to  be  the  watchword.  Everj'thing  is  standardised, 
even  to  the  size  of  the  paper  on  which  the  student  works  in 
pen  and  ink  It  almost  comes  as  a  surprise  that  a  type- 
writer is  not  insisted  on,  and  that  no  American  standard  of 
pronunciation  of  the  letters  of  the  Greek  alphabet  is  set  up. 
The  author  lays  stress  on  the  possibilities  and  responsibilities 
of  character-building  in  a  mathematical  course,  and  we  find 
occasional  hints,  amounting  to  commands,  intended  for  the 
instructor.  Although  the  inspiration  of  Professor  Klein  of 
Gottingen  is  freely  acknowledged,  the  book  should  prove 
innocuous,  and  even  beneficial,  to  English-speaking  teachers 
of  mathematics  dispersed  throughout  the  world. 

W.  D   E. 

Plane  Trigonometry. — Bj'  C.  I.  P.\lmer  and  C.  W.  Leigh. 
288  pages.     9J-in.  x  6J-in. 

(Hill  PubUshing  Company.     Price  6  /3  net.) 

The  treatment  of  the  subject  in  this  book  is  not  at  all 
that  which  has  been  adopted  in  many  recent  textbooks. 
The  authors  begin  with  the  measurement  of  angles,  positive 
and  negative,  and  make  use  at  once  of  Cartesian  coordinates . 
There  is  something  to  be  said  for  this  method  of  procedure  ; 
for  most  boys  are  made  famUiar  with  graphs  nowadays 
before  beginning  trigonometry,  and  it  is  just  as  well  to 
make  use  of  this  famiharity.     The  trigonometrical  ratios 


are  defined  at  the  outset  for  the  general  angle,  and  then 
specialised  for  the  acute  angle.  Many  teachers  have  done 
this  in  times  past,  and  with  success  in  the  case  of  intelligent 
boys.  The  clear  diagrams  in  this  book  seem  to  indicate 
that  the  authors  have  themselves  found  this  plan  successful. 
The  second  part  of  the  book  consists  of  a  xery  good  set  of 
tables,  with  full  explanations,  the  angles  from  0°  to  360° 
being  all  included.  Altogether  the  book  merits  the  attention 
of  teachers,  and  can  be  recommended  without  hesitation 
for  intelligent  students  who  wish  to  obtain  quickly  a 
practical  knowledge  of  the  subject.  By  way  of  criticism, 
it  may' be  said  that  the  saving  of  time  involved  in  writing 
esc  e  for  cosec  e  must  in  practice  be  very  small,  and  may 
cause  confusion. 

\V.  D.  E. 

NATURAL    HISTORY. 

Ktld  Life  :     An   Illustrated  Monthly,   Vol.   VI,    No.    1. — 

Edited    by    Douglas    English.      32    pages.      Numerous 

illustrations.     12-in.  x  10-in. 

(The  Wild  Life  Publishing  Co.     Price  2  /6  net.) 

An  editorial  in  Wild  Life  for  January  frankly  states  that 
its  issue  was  delayed  until  it  had  been  ascertained 
to  what  degree  the  war  had  affected  its  subscription  hst. 
The  fact  that  once  more  the  magazine  has  made  its  appear- 
ance shows  that  the  thanks  offered  to  the  readers  is  not 
an  empty  compliment.  The  number  contains,  as  usual,  some 
excellent  photographs,  of  which  we  may  mention  Mr. 
Oswald  Wilkinson's  picture  of  the  male  willow  warbler 
cleaning  its  nest.  Mr.  Alfred  E.  Tonge  concludes  his 
illustrated  account  of  "  British  Clearwing  Moths."  The 
first  part  of  this  appeared  in  the  December  number,  and 
from  it  we  are  here  permitted  to  reproduce  Figure  59, 
which  is  an  exceedingly  good  representation  of  the  six- 
belted  clearwing  [Sesia  ichneutnoniformis).  Another  picture 
in  the  current  issue,  which  is  very  striking,  is  INIr.  D.  Seth 
Smith's  photograph  of  a  Guinea  baboon,  used  to  illustrate 
Mr.  E.  G.  Boulenger's  monthly  "  Notes  from  the  Zoological 
Gardens." 

W^  M.  W. 

PETROLOGY. 

Textbook    of  Petrology  :     The    Igneous    Rocks. — By    F.    H. 
Hatch.     429  pages.      164  illustrations.     7i-in.  x5-in. 

(George  AUen  &  Co.     Price  7/6.) 

According  to  the  preface,  the  seventh  edition  of  this  well- 
known  textbook  on  Igneous  Rocks  has  been  prepared  in 
order  that  it  may  constitute  the  first  volume  of  a  general 
work  on  petrology,  the  second  volume  being  the  recently 
issued  "  Petrology  of  the  Sedimentary  Rocks,"  by  Hatch 
and  Rastall.  ^^'hile  the  general  arrangement  is  the  same  as 
in  the  fifth  edition,  much  of  the  text  has  been  revised,  and 
new  chapters  on  the  pyroclastic  and  the  metamorphosed 
igneous  rocks  have  been  added.  The  book  is  divided  into 
four  parts,  the  first  being  concerned  with  the  physical 
characters  of  rocks,  the  second  with  the  rock-forming 
minerals,  the  third  with  the  classification  and  description 
of  the  various  rock-types,  while  in  the  fourth  an  account  of 
the  distribution  of  these  types  in  the  British  Isles  is  given. 
The  first  two  parts  are  eminently  satisfactory,  and  the 
facts  are  presented  in  a  most  lucid  and  readable  form. 
The  intioductory  chapters  in  the  third  part  are  not  so 
satisfactorj',  chiefly  owing  to  the  fact  that  the  classification 
adopted  is  that  of  siUca-percentages,  and  that  the  graphical 
methods  of  indicating  the  relation  of  rock-groups,  which 
are  described,  are  the  "  oxide  "  methods  of  Iddings  and 
Broggcr.  No  mention  is  made  of  quantitative  classification, 
either  on  the  basis  of  norm  or  mode,  nor  of  the  exceedingly 
useful  graphical  methods  based  on  these  factors. 

It  is  somewhat  strange  to  find  that  most  of  the  ultra-basic 
rocks  are  relegated  to  the  hypabyssal  division,  as  many  of 
these  are  commonly  plutonic.  This  also  tends  to  obscure 
the  close  relationship  which  sometimes  exists  between 
diorites  and  hornblendites.  The  fourth  part  should  prove 
of  great  use,  as  it  is  very  complete,  though  in  places  it  appears 


64 


KNOWLEDGE. 


February.  1915. 


to  be  not  quite  up  to  date.  Thus,  no  mention  is  made  of  the 
great  variety  of  alkaUc  rocks  described  by  Tyrrell  from 
Ayrshire,  nor  of  Shand's  elaborate  investigation  of  the 
Loch  Borolan  complex.  The  reproduction  of  the  map  of 
the  Loch  Garabal  area  has  the  same  inaccuracies  as  in  the 
fifth  edition.  The  value  of  the  book  is  enhanced  by  a  large 
number  of  excellent  microphotographs,  illustrative  of  rock 
types.  The  figure  of  a  teschenite  on  page  233  apparently 
contains  no  analcite.  As  a  whole,  the  book  is  admirably- 
got  up,  and  misprints  are  rare ;  one,  however,  occurs 
at  the  foot  of  page  185  and  another  on  page  107,  where 
"  hydronephehnite  "  is  used  instead  of  '  hydronephelite." 
In  a  future  edition  more  references  to  papers  containing  the 
original  definitions  of  rock-names  might  be  given.  From  the 
point  of  view  of  the  readers  for  whom  the  book  is  intended, 
these  defects  are  of  small  importance,  and  do  not  detract 
from  the  merits  of  an  edition  which  should  prove  as  useful 
to  students  and  teachers  now  as  previous  editions  have  done 
in  the  past. 

A.  S. 
YEAR    BOOK. 

Penrose's  Annual. — Edited  by  William  Gamble,  F.R.P.S. 
148  pages.    92  illustrations.     10-in.x7-in. 

(Percy  Lund,  Humphries  &  Co.     Price  5/-  net.) 

Penrose's  Annual,  which  is  the  twentieth  volume  of  the 
"  Process  Year  Book,"  is  one  which  should  be  in  the  hands 
of  all  who  are  interested  in  modern  printing  and  illustration . 
The  letterpress  is  a  very  fine  example  of  printing,  though 
perhaps  to  some  the  hues  of  the  heavy  old-faced  type  are 
a  Uttle  too  close  together  to  do  full  justice  to  it.  As  usual, 
the  illustrations  are  exceeding^  good,   and  their  subjects 


very  varied.  There  is  still  a  tendency,  especially  among 
those  used  for  trade  purposes,  to  have  heavy  borders  of 
various  \vidths  and  tints,  which  detract  much  from  the 
effectiveness  of  the  print,  in  so  far  as  they  take  the  attention 
of  the  eye  from  it.  As  the  plates  are  not  numbered  nor 
paged,  it  is  difficult  to  refer  to  any  particular  one  ;  but  we 
think  the  frame  round  the  portrait  of  Mademoiselle  Gina 
Palerme,  with  its  eye-dazzling  corners,  is  an  example  of 
what  should  be  avoided.  The  frontispiece  is  a  portrait  of 
SirWiUiam  Crookes,  P.R.S.,in  colour.  His  academic  gown, 
however,  appears  flat  and  unnatural  ;  and  even  here  we 
cannot  get  away  from  ornamental  borders.  One  of  the 
features  of  the  year  mentioned  by  the  Editor  is  the  develop- 
ment of  rotary  photogravure.  The  article  by  "  Macbeth," 
on  "  Efficiency  in  Press  Advertising,"  is  well  worth  reading. 
Among  many  articles  of  practical  utility  is  one  on  "  Har- 
monic Vibrations  "  by  Mr.  Douglas  Cowley,  following  up 
the  suggestion  that  harmonographs  should  be  used  in 
connection  with  bank-note  engra\-ing  by  proposing  that  they 
should  be  also  used  for  the  borders  of  cheques  or  name- 
plates,  or  as  the  headings  of  various  kinds  of  commercial 
paper.  There  are  still  some  who  think  that  simplicity  is 
bad  taste.  We  fancy  that  more  is  being  done  in  the  way  of 
coloured  collotypes  than  Mr.  Yerbury  seems  to  imagine. 
Mr.  J.  R.  Riddell  asks  the  question,  "Is  a  scientific 
training  necessary  ?  "  and  says  that,  when  one  is  in  a 
reminiscent  mood,  and  compares  the  conditions  and  require- 
ments of  the  crafts  to-day  with  those  in  vogue  some  twenty 
years  ago,  the  answer  must  be  a  most  emphatic  "  Yes." 
We  are  glad  that  the  Editor  did  not  (owing  to  the  war) 
break  the  continuity  of  twenty  years'  consecutive  publica- 
tion, and  decided  "  to  carry  on." 

W.  M.  W. 


NOTICES. 


THE  BRITISH  JOURNAL  PHOTOGRAPHIC  AL- 
MANAC, 1915  (fifty-fourth  issue),  has  just  been  published 
by  Messrs.  Henry  Greenwood  &  Co.,  Ltd.  (price  1  /-  net, 
paper  ;  2/-  net,  cloth).  In  addition  to  the  usual  guide  to 
processes  and  the  handy  tables  of  value  for  reference,  two 
long  articles  appear,  one  on  enlarging  and  the  other  on 
photo-micrography. 

ANTI-VIVISECTION.— A"a/uye  has  a  scatliing  article 
on  the  action  of  the  anti-vivisectionists,  who  are  in\"eighing 
against  protective  treatment  for  tj'phoid  fever.  The  success 
of  the  treatment  and  the  help  which  it  must  give  to  this 
country  in  the  war  are  very  great.  We  wonder  whether 
it  would  not  be  possible  to  show  that  the  anti-\'i\isectionists 
are  prejudicing  enlistment,  and  should  be  dealt  with  under 
the  Defence  of  the  Realm  Act. 

THE  STAR  ALMANAC— Messrs.  Simpkin,  Marshall 
and  Co.  have  issued  the  Star  Ahnanac  for  1915  by  Mrs.  H. 
Periam  Hawkins  (price  6d.  net).  This  contains  much  in- 
fonnation,  and  should  appear  on  the  wall  of  every  astro- 
nomer's stud}-.  Two  other  publications  by  the  same 
authoress  are  invaluable  for  reference  :  The  ABC  Guide 
to  Astronomy  (price  1  /6  net),  now  in  its  third  edition;  and 
the  Revolving  Star  Map  (price  1  /-  net),  an  excellent  plani- 
sphere with  a  movable  declination  scale. 

THE  ALCHEMICAL  SOCIETY.— At  the  sixteenth  meet- 
ing of  the  Society-  the  first  of  a  number  of  papers  forming  a 
symposium  on  mediae\-al  philosophy  was  read  by  Lieutenant- 
Colonel  Jaspar  Gibson,  V.D.,  LL.B.  (Lond.),  on  "  An  Inter- 
pretation of  Alchemical  Symbolism  with  reference  to  the 
Works  of  Edward  Kelly."  In  this  there  were  dealt  with 
certain  analogies  between  the  speculations  of  the  mediaeval 
alchemists,  the  doctrines  of  ancient  Indian  philosophy, 
and  the  theories  of  modern  science.  At  the  seventeenth 
meeting  on  January  8th  the  subject  of  "  Alchemical 
Tradition  "  was  discussed  by  Mr.  Gaston  de  Mengel. 


THE  ROYAL  COLLEGE  OF  SURGEONS  IN 
IRELAND. — The  President,  Vice-President,  and  Council 
of  the  Royal  College  of  Surgeons  in  Ireland  have  decided 
to  place  in  the  College  a  pei-manent  record  of  the  names  of 
all  the  Students,  Licentiates,  and  Fellows  of  the  College 
who  are  at  present  serving  with  His  Majesty's  Navy  and 
Expeditionary-  Forces  ;  and,  further,  to  erect  a  suitable 
memorial  to  all  such  as  fall  in  the  war.  The  President, 
Vice-President,  and  Council  w-ill  be  glad  if  the  relatives  and 
friends  would  communicate  the  names  of  such  Students, 
Licentiates,  and  Fellows  to  the  Registrar  of  the  College. 

ENGLISH  FILTER  PAPERS.— We  are  glad  that  Messrs. 
Balston,  Ltd.,  the  makers  of  the  celebrated  Whatman 
drawing  paper,  are  making  filter  paper  to  replace  that 
wliich  previously  came  from  Germany.  The  specimens 
which  they  have  sent  to  us  have  been  tested,  and  have  been 
found  to  be  rapid  in  their  action,  while  they  effectively 
retain  fine  precipitates.  For  commercial  analysis  and  school 
work  they  are  all  that  could  be  desired.  For  the  most 
accurate  scientific  work,  however,  the  amount  of  ash  is  too 
high,  but  filter  papers  washed  with  acids  are  in  course  of 
preparation  to  meet  the  demand  for  "  ash-free  "  paper. 
We  hope  that  our  readers  will  take  advantage  of  Messrs. 
Balston's  work. 

SHIPLEY  &  MACBRIDE'S  ZOOLOGY  has  been 
thoroughly  revised,  and  the  third  edition  will  be  published 
shortly  by  the  Cambridge  University  Press.  The  science  of 
Zoology  has  made  such  ad\'ances  in  the  eleven  years  which 
have  elapsed  since  the  publication  of  the  second  edition  of 
this  textbook  that  it  has  become  necessary  to  rewrite 
considerable  portions.  The  newer  discoveries  in  the  laws 
of  inheritance  are  dealt  with  in  the  Introduction,  the  chapter 
on  Protozoa  has  been  radically  changed,  a  chapter  on 
Gephyrea  has  been  added,  the  chapter  on  Arthropoda  has 
been  largely  rewritten,  and  many  changes  have  been  made 
in  the  section  dealing  with  Vertebrata.  There  are  many  new 
illustrations. 


February,  1915. 


KNOWLEDGE. 


LONDON  COONTY&WESTMINSTER  BANK 


(ESTABLISHED    IN    1836. 


LIMITED. 


HEAD     OFFICE 


41,    LOTHBURY,    E.G. 


CAPITAL,    i;i4,000,000    IN    700,000    SHARES    OF    £20    EACH. 
PAID-UP    CAPITAL     -      i;3,500,000     I     RESERVE  -         -  i;4,000,000. 

The   Kt.    Hon.    The   VISCOUNT  GOSCHEiN,    Chairman. 

WALTER   LEAF,    Esq.,    Deputy-Chairman. 

Joint     General     Managers: 
F.    J.    BARTMORPK.  J.    \\.     BUCKMURST, 

Secretary : 

A.     A,     KEMPE. 


BALilLlNCK     SHEET,     31st     December,     1314. 


Li.\niLrnKs. 

ASSETS. 

£ 

.s. 

il. 

C.^SH— 

r 

s. 

d. 

£         s- 

d. 

Capual— Siibscribeil £14.000,000 

In  hand  and  at  Hank  of  England 
Money  at  Call  and  .Short  Notice 

22,524,904 
5,634,632 

6 
11 

3 

1 

700,000  Shares  of  £20  each.  £5  paid 

:!,500.000 

0 

0 

2S,159,.'i36  17 

4 

Reserve            

4,000,000 

0 

0 

Bills  Discounted       

18,369,283  11 

7 

Investments  Depreciation  Accoi'nt        

250,000 

0 

0 

'Investments — 

Current  and  Deposit  Accol:nts 

99,312,563 

0 

0 

Consols  (of  which   /1,400,210  is  lodged 
for  Public  .Accounts),  War  Loan,  and 

Circular  Notes,  Letters  of  Credit,  Commission  Loans,  and 

other  Securities  of,  or  guaranteed  bv, 

OTHER  Accounts,  including  pmvisiou  for  Contingencies    ... 

2,019,037 

16 

1 

the  British  (.ovemment       

10.550730 

12 

8 

Acceptances  eor  Custo.mebs           

4,182,337 

1/ 

9 

Goveniment    Guaranteed    RaiKvav 

Endorsements  on  Bills  Negotiated      

93.730 

0 

0 

Stocks  and  Debentures 

l,lo3,4S.3 

6 

4 

Rebate  on  BiLLsnot  due 

96,782 

4 

9 

Corporation     Stocks,     and     British 

Profit  and  Loss  Balance,  as  below         

531,987 

3 

3 

Railway  Debenture  Stocks 

Othoi  Iii\?stnients 

1,221  463 
1,736,440 

b 

7 

11 

8 

14.647,092  12 

- 

This   statement   does  not   include   the   Bank's   liability 

LONIH)N      COUNTV      .AND      WeST.MINSTER      BaNK 

under  its  euarantee  to  the  Yorkshire  Pennv  Bauk, 

(l'.\Ris)  Limited — 

Limited,  for  £223,214. 

4,000  £20  Shares  fully  paid         \ 
16,000  £20  Shares  £7  iOs.  paid    /- 

.Advances  to  Customers  and  other  .Accoun 
iiioratoriinn  Stock  ExcJiance  Loans)     ... 

200,000    0 
46,617,340  18 

0 

rs  (includin 

?  pre- 

*  Investments  officially  quoted  have  been  valued   at  or 
under  prices  current  on  27th  Julv,  the  date  of  the  last 

5 

official  making  up  before  the  closing  of  the  Stock 

Liability  of  Customers  for  .\ccfptences, 

as  per  contra 

4.182,337    17 

9 

Exchange.       Investments    made    since    that    date 
are  valued  at  cost  or  under. 

Pills  Negotiated,  as  per  contra     

93,730    0 

0 

Bank  and  other   Premises  fat  cost,  h-Si  amounts  wntten  o9) 

1,717,106    4 

2 

£113,986,428 

1  10 

£113,986,428    1  ID 

2)r.                                                                             PROFIT    AND 

LOSS 

ACCOUNT. 

Cr. 

To  Interest  paid  to  Customers           

,,   Salaries  and  all  other  expenses,  including  Income  Tax  and 
.Auditors' and  Directors' Remuneration      

,,   Rebate  on  Bills  not  due  carried  to  New -Account 

„  Interim  Dividend  of  lOJ  per  cent,  paid  in  .August  last 

„   Amount  written  off  Investments,  for  Depreciation 

,   Further  Dividend  of  10^  per  cent.,  payable  1st  February  next 

{making  21  i  per  cent,  for  the  year)  ...          £371,875'  0     0 

,,  Balance  carried  forward '.         ...           160.112    3    3 

£         s. 
922,586  12 

1,299,809  12 

96,782    4 

371,875    0 

336,600    0 

531,987    3 

d. 

1 

5 
9 
0 
0 

3 

By 

£     s. 

Balance  brought  forward  from  31st  De- 
cember, 1913      

Gross    Profit    for    the    year,   after   making 
provision    for    Bad    Debts    and    Contin- 
gencies,  and  including   Rebate  brought 
forward  from  31st  December  last      

d.            £          s.    d. 
156,644  11     6 

...      3,402,996    1    0 

£3,559,640  12 

6 

£3,559,640  12    6 

GOSCHEN. 

WALIER   LEAF,  , 

MONTAGU   C.   TURNER,    ) 


I 


AUDITORS'     REPORT. 


F.  J.  BARTHORPE,   \Joml  General 
T.    W.    BUCKHURST.  /     Maiiaaer!. 
t.  J.  CARPENTER,   Chief  .icmmlani. 


We  have  examined  the  above  Balance  Sheet  and  compared  it  with  the  liooks  at  Lothbury  and  Lombard  Street,  and  the  Certified  Returns  received  from  the  Branches. 

We  have  veritied  the  Cash  in  hand  at  Lothbury  and  Lombard  Street  and  at  the  Bauk  of' England   and  the  Bills  Discounted,  and  examined  the  Securities  held  against 
-Money  at  Call  and  Short  Notice,  and  those  representing  the  Investments  of  the  Bank. 

We  have  obtained  all  the  information  and  explanations  we  have  required,  and  in  our  opinion  the  Balance  Sheet  is  properly  drawn  up  so  as  to  exhibit  a  true  and  correct 
A'iew  of  the  state  of  the  Company's  affairs  according  to  the  best  of  our  information  and  the  explanations  given  to  us,  and  as  shown  by  the  Books  of  the  Company. 

FRED.    JOHN    YOUNG,    F.C.A.,     I      ,     ,., 

London,  \m  January,  1915.  G.    E.    SENDELL,    F.C.A.,  |    Auauors. 


KNOWLEDGE. 


February,  1915. 


"B.J.  ALMANAC  1915,"  The  big  book  of  photo- 
graphic tormulae  ;  all  methods,  hints,  etc.;  over 
1000  pages.      Now  ready. 

"  B.J.  ALMANAC  "  contains  a  comprehensive  treatise 
on  "  Photo-Micrography,"  by  Dr.  Duncan  J.  Reid. 
From  your  flealer, 

"BRITISH  JOURNAL  PHOTOGRAPHIC  ALMANAC. 

1915."  A  libran-  -n  itsell.  From  all  pliotngraphic 
dealers.  Pi-ppr  co\'er  1  /-  )icl,  cloth-bound  2/-  net ; 
or,  post  free,  from  the  Publishers,  HENRY 
GREENWOOD  &  CO.,  LTD..  2A,  Wellington 
Street,  Strand,  W  C,  Paper  cover  1  /6  "t■^ 
cloth-bound  2/6  >u'l.    Abrnntl,  2/-  and  o'-. 


CLARKSON'S 

SECOND-HAND 

OPTICAL    MART. 


TELESCOPES. 


,'  -ifi  W'ray, mount- 
ed on  massive  oak 
lath  stand  with 
stretchers,  hori- 
zontal and  vertical 
movements  by 
Hooke's  joint, 
slow  motions.large 
finder,  4  astro,  and 
I  da\-  eyepieces  -  -  £40 

ll.Negretti 
&  Zambra  aha/-, 

tuider.      I     .lav,      -. 


4-1 


a^tros.,  in  case  ..  ..     25     o  o 

3i-iii.    Baker,    on   altaz.    stand,     horizontal 

and    vertical  motions,    finder,  day   and 

2  astros.  ..  ..  ..  ..17100 

3i-in.  Dollond,    on  aliaz.  siani.1,  finder,  da>- 

and  2  astros.  .  ..  ...     12    10  O 

3-in.    Steward,    on    altaz.    with    equatorial 

(undivided  circles),  i  day,  2  astros.  ..  I  I  10  O 
j-in.  Wood,   I  ;istro.  and  r  dav  eyt;pit;ces    .  4     o  O 

Manyotherj..      AK"  !''.\'-pi*-i  ■--.,  i'lu-i-Ts,  Diasonals,  etc. 


MICROSCOPES. 


■  S    15  o 


Handle  Model. 


8     8 


6   15 


Watson     '*  Edinburg^h 

Student's  *'    llimn.u- 

lar,  3  eyepieces.    2-iii., 

i-in.,       A-in.,      polari- 

scope,  and  case 
Watson     "  Hdinburgh 

H,"  2/3,  1/6, 1/12  o.i., 

2       eyepieces,       triple 

riosepiece,     and     Abbe 
Baker  "D.P.H."  Stand, 

triple  nosepitfce.  Abbe, 

and  case 
Beck's  Lartje '*  London" 

spiral,  Abbe    and    iris,   triple  iiosepiece, 

2  eyepieces,  2/3  and  1/6,  as  new  , . 
Watson      "Fram,"     eyepiece,    spiral. 

Abbe  and   iris,  double  nosepiece,   2/3 

and  1/6 
Beck    Small   "London,"   spiral,   Abbe 

and  iris,  double  nosepiece,  23  and  1/6         6100 
Swift     "Discovery,"     eyepiece,     2/3. 

1/6,  doubl'.- nosepiece     ..  '        .,  .,         5    1 5     o 

Baker    Student,    eyepiece,    A    and    D 

Zeiss  objectives,  double  nosepiece      ..         5    10     O 
Bausch  &  Lomb  Student,  i  eyepiece 

double  nosepiece,  2/3  and  1/6.  -  . .  S      O     O 

Many  others.  AKo  Objectives  (a  large  stock  by  all  ihe 
leadnig  makers),  Eyepieces,  Double  and  Triple  Nose- 
pieces,  Condensers,  Lamps,  Spectrosropes,  Microtomes, 

PRISM    BINOCULARS 

BY 
ROSS,     ZEISS. 
GOERZ,    etc., 

FOR  SALE 

AND 
WANTED. 


338 


HIGH  HOLBORN 

(Opposiic  C,i.:\\  Inn  Recall, 

LONDON. 


MICROSCOPY. 

SPECIALLY     ATTRACTIVE     SLIDES 
FOR   POPULAR   EXHIBITION  tV:   STUDY. 

Zoology.  Marine  and  Freshwater.— 

Unique  preparations,  i.vithoi(t pyfssityc,  in  their  natural 
form  and  beauty  for  Dark  Ground  (or  transparent). 
Zoophytes^  Medus(P,  Polyzoa,  with  their  glorious  array 
of  tentacles;  Holothurians  with  wheel  plates,  etc.  ;  a 
series  of  the  curious  Salptp  and  other  Tunicates  ;  young 
(j-<'(^/£\v  developing  in  their  eggs  ;  the  celebrated  Lance- 
let  ;  also  the  Radiolarian  Spluprozouin,  the  "  Volvox  of 
the  sea,"  etc.,  etc. 

Insects  and  Parts. — V.a.r\B.oi Plumed  Gnat 
(also  for  polariscope).  Superb  tongues  of  the  rare 
Sylzian  IVasp  and  Hornet,  also  piercing  organs  of  the 
Cacl^y,  etc.,  etc. 

Specia 


Cements.     Forceps,     Scissors,   etc., 
Mounlin-ii  and    Dissecting- 


for 


SECOND-HAND 

INSTRUMENTS, 

OBJECTIVES,  &c. 

NEW    LIST 

NOW    READY. 

Post  free    on    request. 


To  Beginners.— K.xpert  advice  freely  given 
on  selection  ■.>f  snUaMe  equipment;  much  time  and 
neeilless  expense  ^:an  thereby  be  saved.       Write  or  call. 

UfAMTCn       Microscopes,  Objectives,  etc.,  or  whole 
ttwn  ii-MJt  Outfits  purchased  for  Cash. 

KXCHANGES    MADE. 

CLARKE   &    PAGE, 

23,   Thavies  Inn,    Holborn  Circus,   LONDON. 


LIVING    SPECIMENS 

FOR     THE 

MICROSCOPE. 

Volvox  globator,  Desnilds,  Diatoms,  Spirogyra, 
Aniceba,  Actinophrys.  Spongilla,  Vorticella,  Stentor, 
Hydra,  Cordylopohra,  Stephanoceros.  jMelicerta. 
Polyzoa.  and  other  forms  of  Pond  Life,  Is.  per  tube, 
with  printed  drawing,  post  free.  Thomas  Bolton, 
Naturalist,  25,  Halsall  Heath  Road,  Birmingham. 

MINERALS 

FOR   ALL    PURPOSES 

I N  (  r  r  1 )  I N . . 

Experiment, Wireless,  Incandescent  Mamies, 
Radio-Active,  Steel  Making,  &c.,  &c. 

JAMES  R.   GREGORY  &  Co., 

Mineralogists,  &c., 

139,  Fulham  Road,  South  Kensington,  S.W. 

Telephone  :     Westerii  •J,S41. 
Telegrams:    "Meteorites,  Loiulon." 


SECOND-HAND  DEPARTMENT. 

Microscopes,    Telescopes,    Spectroscopes, 
Binoculars,  Surveying  Instruments,  &c., 

BY  THE  BEST  MAKERS  AT  MODERATE  PRICES. 

Lists  sent  post  *ree  on  request. 

Scienh'/Ic   lnst>ui'!i->its   Bou^'il.   E.i\h.i>i^^t\i  and  Sold 
on  L  onuHisshin. 

JOHN     BROWNING, 

146  STRAND,  and  72  New  Oxford    St., 

LONDON. 


1  elegranis ; 
'AUK.S,"  LONDON. 


leltiphone 
8:i4  GKRRARD. 


Established      i760 

Stevens'  Auction  Rooms, 

38,  KING  ST,,  COVENT  GARDEN,  LONDON,  W.C. 

Every  Friday  at  12.30,  Sales  are  held  at  the 
Rooms  of  MiCKOScopES  and  Slides,  Tblescopes, 
Surveying  Instkuments,  Electrical  and  Scien- 
tific Apparatus,  Cameras  and  Lenses,  Lanterns 
AND  Slides,  Cinematographs  and  Films,  in  great 
variety.  Lathes  and  Tools,  Etc. 

(Joods  may  be  sent  for  inclusion  in  early  Sales. 

Settlements  made  one  week  after  disposal. 


Catalogues  and  all  Particulars  Post  Free. 

Valuations  fur  Probate  or  Transfer,    and  Sales  cnn. 

dueled  in  any  part  of  the  Ciiuntr>. 

Minerals,  Rocks,  Fossils,  Metallic 
Ores,  Rough  Precious  Stones,  &c. 

A  Large  Assortment  from  all  parts  of  the  world  always 
on  view,  and  at  all  prices.     Inspection  invited. 

Crude  Mineral  for  Chemistry  Students 

aad  TechiiJcai  Sctools. 

Single  Cystals  and  Teaching  Specimens  m  Great  Variety. 

RICHARDS'  SHOW  ROOMS. 

48  Sydoey  Street    Ftilbam  Road,  South  Keasington, 
London,  S.W. 

rRicii  Lii  r^  I  Ri  I 


F.  WIGGINS  &  SONS, 

102,  t03, 104,  Mmories,  LONDON.  E 


Contractors  to  H.M 
Government 


FOR 

LAMPS, 

STOVES. 

VENTILATORS, 

ELECTRICAL     WORK 

AND    ALL    PURPOSES. 

Largest  Stock  in  the  World.    Tel.  No.  2248  Avenue. 


Printer  of 
"  Knowledge," 


JOHN    KING, 

Uxbridge,  Southall,  and  Ealing, 

T  s  favourably  equipped  for  the  PRINTING  of 
*■  Scientific  Books,  Brochures,  Catalogues,  .S;c.,  and 
will  be  pleased  to  submit  estimates. 

Address  all  Communications  to 

213,    UXBRIDGE    ROAD,    EALING,    LONDON,    W. 

■Plioce:    1144   EaliOfi- 


Binding  Cases  for  Knowledge  Volume,  1914. 

IN    BLUE    CLOTH,    WITH    GILT    DESIGN    AND    LETTERING. 

!s.   '.lit.   net   each;    by   Post,   2s. 


KNOWLEDGE  OFEICE,  ,\veiuie  Chainbers.  Bloomsbiirv  Square,  Lnmlcn,  W.C. 


A    most  acce/ttable   Gift   at  any   time 

KNOWLEDGE     VOLUME      FOR      1914 

Containin^i  440   Pa^es   "itli    425   Illustrations,    many  being   Full   Page  Plates. 

Boiiini   ill    Rliip  Cj-itii,    (hIi    [i..--,i-ti  .ni.l    1  ,r:i  fri  in  u ,    15,-    lit.-!,   prist   free  within   the  United    Kin-iloni. 


Publishing  Office:  AVENUE  CHAMBERS,  BLOOMSBURY   SQUARE,  LONDON,  W.C,  or  through  any   Bookseller. 


February,  1915. 


KNOWLEDGE. 


vu. 


WATSON'S 
BRITISH-MADE 
MICROSCOPES 

Special  arrangements  have  been  made 
for  prompt  supplies  of 

Watson's  Microscopes  and  Accessories 

to  replace  those  of  Continental  mabe  that  are 
unobtainable  in  consequence  of  the  War. 

NO     INCREASE     IN     PRICES 


The  24^.''  Edition  of  Watson's  Gataiogue 
of  Microscopes  and  Accessories, 

192    pages,  has   just   been   issued,  and   contains   new 
models,  new  accessories,  and  many  improvements. 


Make  Your  Monocular  into  a  Binocular 

Microscope.     It   can   now   be  done   by  the 
use  of  a  WATSON'S   New 


"BICOR" 

BINOCULAR 

ATTACHMENT 

(Patent  applied  for) 

It  offers  many  advan- 
tages, among  which  are 
the  following : — 

It  is  attached  to  a 
Monocular  Microscope 
in  the  same  way  as  a 
Revolving  Nose-piece. 

Tube  length  can  be 
varied  and  interocular 
width  adjusted  to  any 
extent. 

Brilliance  of  image  in 
both  tubes  the  same. 

No  sacrifice  of  defi- 
nition is  observable. 

The  above,  with  many 
other  important  improve- 
ments and  introductions, 
including  a  series  of 

APOCHROMATIC 
OBJECTIVES, 

are  to  be  found  in  Wat- 
son's     newly -published 
Catalogueof  Microscopes. 
\Posi  free  on  application. 


"Bicor"  Binocular  Attachment. 
"A'"  Screw  to  attach  to  Monocular  Body, 
"B"  Screw  to  receive  Objectives. 
*C"  Screw  to  adjust  for  width  of  eyes. 


W.  WATSON  &  SONS,  LTD., 

Contractors  to  Ib./IE).  Covernments, 
313  HIGH  HOLBORN,  LONDON,  W.C. 

Branches : 
16  Forrest  Road,  Edinburgh ;   196  Great  Portland  Street,  London,  W. 

DEr6T5 : 

2  Easy  Row,  Birniinflham;   78  Swanston  Street,  .Melbourne,  Australia; 

212  Notre  Dame  Street  West,  .Montreal,  Canada. 

ptical  Works— HIGH  BARNET,  HERTS.       ESTABLISHED  1837. 


The  BECK  BINOCULAR 


BECK  BINOCULAR  MICROSCOPE. 

No.  1031  P.S. 


(Patent   applied   for) 

Not  only  an  advance  on 
previous  Binoculars,  but 
better  than  a  iMonocuiar 
with  all  powers. 

1.  Resolution  equal  to  that 

of  a  Monocular. 

2.  Equal     illumination     in 

both  eyes. 

3.  Short  tube  length,  mak- 

ing Microscope  com- 
pact. 

4.  No     special     object- 

glasses  or  eyepieces 
required. 

5.  Standard  angle  of  con- 

vergence. 

6.  Stereoscopic  vision. 

7.  Binocular  vision,  saving 

eyestrain  and  giving 
better  results  than 
Monocular  vision. 

8.  Converted  into  a  Mon- 

ocular by  a  touch. 


Full  descriptive  Booklet  and  Price  List  on  application. 


R.&J.BEGK,L'^.'68Gornhill,London,E.G. 


DENT'S   CLOCKS 

WATCHES  AND  CHRONOMETERS 

FOR    SCIENTIFIC    USE. 

Sidereal   op   Mean    Time    Clocks    for 
Observatories,  £21  and  up>vards< 


THREE  GRAND  PRIZES 
AND  ONE  GOLD  MEDAL 

FRANCO -BRITISH      EXHIBITION. 


The  only  Grand  Prize  awarded 
to  a  British  Firm  for  Watches, 
Clocks  and  Chronometers. 

The  only  Qrand  Prize  awarded 
for  Astronomical  Regulators, 
Chronographs,  and  5hip's 
Compasses. 


TRADE    MARK 


61,  STRAND,  and  4,  ROYAL  EXCHANGE,  LONDON. 

Telephone  So.  61  City. 


ADVERTISEMENT     RATES. 

Whole   Page £6    6    O. 

Half  Page         3     S    O 

Quarter  Page  1   15    oK,' 

One-Eighth  Page 0  18    6'kj 

One  Sixteenth  Page O  10    OS; 

Pep  Inch,  Narrow  Column  O     7    Ol 

Half    ,.  „  „  O     4    0-' 

Discounts  for  Series  of  Insertions  and    Rates   for   Special   Positions,   when 

Vacant,  on  application  to  The  Advertisement  Manager, 
Knowledge  Olfice,  Avenue  Chambers,  Bloomsbury  Square,  London.  W.C. 


BEST 
COCOA I 


SCHWEITZER'S 


EARTH.; 

GUARANTEED  ABSOLUTELY  PURE^OLUBLECOCOAONLY. 


KNOWLEDGE. 


February,  1915. 


NEW    MODEL 

FS   and    FFS 

pauscK'lomb 
MICROSCOPE 

WITH  SAFETY  SIDE  FINE  ADJUSTMENT. 


Catalogue 
No. 

Objectives. 

Eve- 
pieces. 

NOSEPIECBS. 

Abbe 
condensek. 

Dry. 

OUIm- 
mersion. 

Price. 

i   s.    d. 

FS         1 

16  mm  4  mm 

— 

7-5  X 



6    5    0 

FS       2 

16  mm  4  mm 

— 

7-5  X 

Circular  Double 



7    1     6 

FS        3 

16  mm  4  mm 

— . 

5X    lOx 



6  11     0 

FS        4 

16  mm  4  mjn 

— 

5x    lOx 

Circular  Double 



7    7    6 

FFS     6 

16  mm  4  mm 

— 

5x    lOx 

1-20  N.A. 

8  15    0 

FFS     8 

16  mm  4  mm 

1  -9  mm. 

5x    lOx 

Circular  Triple 

1-20  N.A. 

14     0     0 

KEW    ATTACHABLE    MECHANICAL    STAGE.     No.    2116,     £3    S    0 

We  have  sold  over  100,000  Microscopes,  which  are  in  use  all  over  the  world. 

Inspection   incited  at  our  New  Showrooms,  or  List  "A.S.  2"  sent  post  free. 


N.B.— ALL  OUR  INSTRUMENTS  BEING  MADE  AT  OUR  OWN 
FACTORY  IN  ROCHESTER,  N.Y.,  THERE  WILL  BE  NO  DELAY  IN 
DELIVERY,     AND     WE     HAVE    JUST     RECEIVED     LARGE     STOCKS. 


Trade  Mark. 


BAUSGH  &  LOMB  OPTICAL  CO., 37-38  Hatton  Garden  London,  E.G. 


Or  through 
all  Dealers. 


JAMES  SWIFT  &  SON, 

Optical  and  Scientific  Instrument  Makers, 

Cofiit-actoJS  to  all  Scientific  Pcpa> ti'rents  c/  H.M.   Gffft. 

Grands    Prix,    Diplomas    of    Honour,   and    Gold 
Medals  at  London,  Paris,  Brussels,  &c. 


NEW    (( 

MODEL 


I.M.S.'MIGROSGOPE 

SPECIALLY    DESIGNED    FOR 
BACTERIOLOGY    AND    HiEMATOLOGY. 

With  Improved  Fine  Adjustment  and  Special 
Mechanical  Stage. 

Fitted  with  s-in.,  |-in.,  and   1'5-iii.    (Oil   Immersion) 
■^  Objectives,  Oculars,   Triple   Dust-proof   Nose-piece, 
^  Abbe  Condenser,  Ins  Diaphragm.  Mechanical  Stage, 
etc.,  in  Cabinet.  £23. 

N3. — All  oar  Microscopes  (including 
the  Lenses)  are  made  in  oor  own 
workshops  on  the  Premises. 

Catalogue  Post  Free. 

UNIVERSITY  OPTICAL  WORKS,  81,  Tottenham  Court  Road,  LONDON,  W. 


Microscope  Slides. 

BOTANY  -  ZOOLOGY  -  GEOLOGY^ 

LARGE  STOCK  IN  ALL  BRANCHES. 
SELECTIONS  SENT  ON  APPROVAL. 

Special  Slides  mounted  to  order  from  Customers'  own  Material. 

—  PHOTOMICROGRAPHY.  — 


CATALOGUE 


FREE    ON    APPLICATION. 


FLATTERS    &    GARNETT,    Ltd., 

309,  OXFORD  ROAD  ('SESi,';"),  MANCHESTER. 


THE  "PEANDAR"  ELECTRIC 
SELF-RECORDING  ANEMOMETER 


Showing  inside  the 
house  (from  any  dis- 
tance), on  the  dial,  the 
total  miles  of  wind 
passed,  and  on  the  chart 
a  weehly  record  of  the 
periodical  variations. 


Special  contacts  have 
been  devised  which  pre- 
vent the  current  being 
left   on   at   any  time. 


PRICE  COMPLETE, 
with  wire,  batteries, 
ink,  and  charts  lor  a 
year,  in  baodsome 
oak,  mahosany,  or 
walant  case,  with 
bevelled  plate  glasses, 

£22 


Easily  Fixed  by 
any  Mechanic. 


M--  PASTORELLI  &  RAPKIN,  LTD.,  "- 

Contractors  to  H.M.  Government, 

46,     HATTOM     OARDEM,     LONDON,     B.C. 

ACTUAL  MAKERS  OF  ALL  KINDS  OF  METEOROLOGICAL  INSTRUMENTS. 

IV  Wri^e  for  Illustrated  Descriptive  Lists  of  Standard,  Self-Registering,  and  Self- 

Recoiding  Instroments,  post  free. 
*,.■  We  pay  carriage  and  guarantee  safe  delivery  within  U.K.  on  all  our  Instruments. 


Printed  for  the  Proprietors  (Knowledge   Publishing  Company,  Limited),  by  JOHN  King,  Ealing  and  Uxbridge.— February,  1915.