IN MEMOKIAM.
George Davidson
182^-1911

Professor of Geog.
Univ. of Calif.

SIR,

I HAVE the honor

Eoyal Observatory, mentioned <\

by authority of the Lords Coin
be -Ofx forwarded

'T OFFICE,

Vrancisco, Cal.

*I request the favor of tin ;
F luive t'

Your

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Non-Ooiiipliiiiuv with thic i\'qiu'.-t \vil!

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' & T 1500 12—80

ACCOUNT

OF

OBSERVATIONS

OF

THE TRANSIT OF YENUS,

1874, December 8,

MADE UNDER THE AUTHORITY OF

THE BRITISH GOVERNMENT :

AND OF

THE REDUCTION OF THE OBSERVATIONS.

EDITED BY

SIR GEORGE BIDDELL /AIRY, K.C.B.,

ASTRONOMER ROYAL.

AUG 25 1952

UNIVERSITY' of

PRINTED FOR HER MAJESTY'S STATIONERY OFFICE,

UNDER THE ADTHORITT OF

THE LORDS COMMISSIONERS OF HER MAJESTY'S TREASURY.

1881 >

INDEX.

Page

INTRODUCTION .... - - iii

PART I. — EXPEDITION TO THE HAWAIIAN (SANDWICH) ISLANDS - 1

Section 1. — Observations at Honolulu (Oahu) 3

Section 2. — Observations at Kailua (Hawaii) - 211

Section 3. — Observations at Waiinea (Kauai) - - 235

PART II. — EXPEDITION TO EGYPT . . 257

Sectionl. — Observations on the Mokattam Hills (Cairo) - - 259

Section 2. — Longitude of Alexandria - 319

Section 3. — Observations at Suez - - 331

PART III. — EXPEDITION TO THE ISLAND OF RODRIGUEZ - 347

Section 1. — Observations at Point Venus - 349

Section 2. — Observations at Point Coton - - 379

Section 3. — Observations at Hermitage Islet - 389

PART IV. — EXPEDITION TO KERGUELEN ISLAND - 401

Section 1. — Observations at Observatory Bay - 403

Section 2. — Observations at Supply Bay . - - 449

Section 3. — Chronometrical Connexion of Stations in Royal Sound - 465

Section 4. — Observations at Thumb Peak - 473

PART V. — EXPEDITION TO NEW ZEALAND - - - - - 481

APPENDIX - (I)

I. — Extract from Instructions to Observers - (1)

II Corrections to the Tabular Right Ascension of the Moon - (2)

III. — Tabular Geocentric Elements of the Positions of the Sun and Venus - (3)

IV. — Specimens of the Skeleton Forms Nos. 17, 18, 19, 20 - - (7)

V. — Photographic Operations on the Transit of Venus - - (14)

Determination by Curves, of the law of Distortion - - - (16)

Table of Numerical Corrections for Distortion of Photographs - (16) and (17)

Apparatus for rapid formation of Photographs - - (19)

Specimen of Form 22 - (20)

Specimen of Form 21 - - - - (21)

INTRODUCTION.

THE first occasion, I believe, in late years, on which the attention of the
British public was pointedly called to the approaching Transits of Venus, was
ray communication to the Royal Astronomical Society, dated 1857, April 8,
" On the means which will be available for correcting the measure of the
Sun's distance in the next 25 years." This paper was not limited to the
consideration of Transits of Venus, a part of it being devoted to the Oppo-
sitions of Mars. Much attention, however, was given to the selection of
stations for observation of the Transits both of 1874 and of 1882.

On 1864, May 5, I addressed another communication to the same body,
relating only to the Transit of 1882, and to the necessity for a reconnoissance
of antarctic countries if an observation with the Sun below the pole should be
contemplated.

On 1868, October 10, I began a correspondence with the Hydrographer,
Captain (now Sir George) Richards, on the general subject.

On 1868, December 11,1 read a communication to the Royal Astronomical
Society, " On the Preparatory Arrangements which will be necessary for
efficient observation of the Transits of Venus in the years 1874 and 1882."
This paper was accompanied with eight maps of the regions which appeared
proper for the observations of. Ingress and Egress, accelerated and retarded
by Parallax, in the two Transits. An active discussion followed, in which the
Hydrographer and several Navy Officers took a prominent part.

On 1869, February 15, I sent certain papers to the Secretary of the
Admiralty ; on April 9 I wrote more formally with Estimate of Expense of
Instruments ; and on May 25 I sent a printed copy of the discussion of
1868, December 11, including also a paper by Mr. De La Rue on the
application of Photography. About the same time an Estimate was
furnished by the Hydrographer for expenses of travelling, residences, &c.
[Each of these estimates proved ultimately much too small, the deficiency of
my own being mainly in respect of observing-huts and general packages.]
Approval to a certain extent was given by the Admiralty, and instrumental
and other preparations were begun. Those transactions were reported to the
House of Commons on July 6.

Q ni. wt. 17091. a 2

M761607

iv TRANSIT OP VENUS, 1874.

The Board of Visitors of the Royal Observatory, at their meeting of 1871,
June 3, passed the following resolution : — " After a discussion it was
" resolved, that, — as the Board deem it most important that photographic-
" be combined with eye-observations at the approaching Transit of Venus,
" an opinion in which the Astronomer Royal fully concurs, — the Chairman
" apply to the Lords Commissioners of Her Majesty's Treasury to sanction
" a grant of five thousand pounds (5,0001.) for the purpose ; a sum which it is
" considered will cover the cost of photographic apparatus and observations
" for all the stations." The Board of Admiralty requested my opinion on
this proposal, and in reply, though expressing myself guardedly on its success,
I gave my opinion in favour of it.

Meantime the general plan of the proposed Expedition had become the
subject of much public discussion ; and in particular, letters appeared in the
" Spectator" of 1873, February 8, and the " Times" of February 13, strongly
urging the adoption of Bnderby Land (which after careful consideration I
had rejected) for a southern station. The Board of Admiralty sent these
papers for my opinion, and in my reply, dated February 21, after elaborate
discussion of the question, I declined to recommend that adoption. At their
Lordships' request, my reply was communicated to the Royal Astronomical
Society, and it is printed in their Monthly Notice of 1873, March 14.

On 1873, March 22, a statement on the general plan was made to the
House of Commons.

Preparations had now advanced for collecting an efficient body of observers
from all classes, Naval, Military, and Civilian, and for their instruction at the
Royal Observatory in all the practical details of observation with the Transit,
the Altazimuth, the Equatoreal, and especially with the working model of
the Transit. Among the candidates who early offered their services was
Captain Gr. L. Tupman, R.M.A. I soon found that this gentleman might be
trusted with a large portion of the superintendence of preparations and
instructions, which, amid the engrossing business of the Royal Observatory,
it was impossible for me to undertake completely. On 1873, March 21, I
gave in an elaborate Report of preparations, and stated that valuable
assistance had been received from Captain Tupman.

The Board of Visitors of the Royal Observatory, at their meeting of 1873,
June 7, passed the following resolution : — " That in consideration of the fact
" that the successful result of the entire scheme of observation of the

INTRODUCTION. v

" approaching Transit of Venus will depend to a great extent on observations
" being made in the Southern Hemisphere, to compare with those which are
" already amply provided for in Siberia and China, it is in the opinion of
" the Board of Visitors very desirable that parties suitably equipped be
" despatched to the South, in the hope of finding some additional practicable
" places at which the entire duration of the Transit may be observed." The
Admiralty, in reply to the Board of Visitors, adverted to the voyage of the
" Challenger," and to the prudence of waiting for reports from that ship. I
may here state that subsequent information thus obtained justified the entire
rejection of the Heard Islands, on account of the extreme uncertainty of
communication (the Crozet Islands had been previously rejected for the same
reason), and indicated unexpected facilities in the adoption of the southern
part of Kerguelen Island.

On 1874, January 24, I placed before the Admiralty a general statement of
arrangements, and on March 11, Captain Tupman was first put in commu-
nication with the Accountant-General, the Director of Transports, and the
Hydrographer, for management of the expedition when afloat and of its
money-affairs. On May 4, in reply to a letter of the Admiralty, I offered my
strong testimony to the value of Captain Tupman's services.

The greater portion of the observing parties sailed in the early part of
summer ; that for Egypt naturally much later than the others. Time,
however, was occupied by the Egyptian party at Greenwich in practice for
the operations with the long submarine telegraph. The several parties
returned at different times : the breaking up of their residences depending,
for the most part, on the completion of operations for longitude. On those
points information will be found in the several Parts of the following work.

Some advance had been made by each party in the orderly record and
partial reduction of their observations. As soon as Captain Tupman returned,
all the observers were placed under his superintendence, at the Royal
Observatory, for completing their share of the reductions and for measure
of the photographs. As the work of each observer was finished, he was
discharged from the service. The last was Lieut. Neate, R.N., from
Rodriguez ; his return was late, and his calculations voluminous ; and they
were not finished before October 1876.

From this time every calculation was subjected to the severe examination
of Captain Tupman.

On 1877, April 14, a member of the House of Commons gave notice to the
First Lord of the Admiralty of his intention to inquire, on April 19, when

vi TRANSIT OF VENUS, 1874.

the Results of the Observations, &c. might be expected to be laid before
Parliament. In consequence of this, every effort was made by Captain
Tupman to accelerate partial reductions and to combine the results ; and a
Return was made to the House of Commons, dated 16th July 1877, and was
ordered for printing on the same day. The substance of this Report, as
regards observations, &c. is entirely included in the details of the present
volume.

In the meantime the affairs of the Transit of Venus were in great difficulty.
Captain Tupman, with scarcely any assistance, was occupied with the vast
mass of reductions. The Government, probably remarking the excess of
expenditure above estimate, refused to sanction his stipend beyond 1878,
March 31. Captain Tupman then addressed to me the following letter : —

" 1877, November 7.

" I cannot allow a mere pecuniary consideration to prevent me finishing off
properly the work I have had so much to do with. The Lords of the
Admiralty will allow me to remain under you as long as you please, although
they cannot grant special salaries.

" Perhaps things will be nearly completed by the end of March 1878. I
hope to see the work through the press, and all the books and stores left in
first-rate order.

" G. L. TUPMAN."

This determination of Captain Tupman was repeated on 1878, March 16.

"With the assistance of one computer (whose salary was paid by myself for
a long time, but was ultimately reimbursed to me) Captain Tupman
continued his work gratuitously, examining severely every step of the
observers' computations, and more especially all that related to instrumental
adjustments. Never, perhaps, was such an enormous mass of calculations so
severely criticized, and, where necessary, repeated ; but it lasted much longer
than had been anticipated. The authority of the Government had been
received for printing the results ; and this, on the scale adopted by Captain
Tupman, added greatly to his labour. However, in the autumn of 1880
Captain Tupman, then about to quit the country, presented me with the
calculations and portions of introductions for each station, and with the
printed sheets for the observation-districts of the Sandwich or Hawaiian
Islands and Egypt. Though anticipating for myself a heavy addition to
the labours of an office already sufficiently oppressive, I could but feel
grateful to Captain Tupman for the disinterested zeal — I may call it heroic—
with which he had laboured to bring the work to that point.

INTRODUCTION. vii

The observations and reductions, I found, had been printed in great detail,
especially for the district of the Sandwich Islands. It was desirable that this
should be done to some extent as a general specimen of the operations ; but
I now determined to print the remainder on the scale which I had intimated
in an address to the Royal Astronomical Society, published in their Monthly
Notice for 1875, March 12, " In the accounts of transits it is sufficient to
" give description of instruments and methods, constants of adjustments,
" and tables of clock-errors, and analogous abstracts of comparisons of
" chronometers, &c. But it is necessary to give in the fullest detail
" everything that bears upon the actual observation of contacts, or upon
" the observer's impression at the time of making the observation, or upon
" the micrometer-measures, or upon the photographs and the measures
" of the photographs, &c. ; with sufficient description of the instruments and
" their adjustments at the time. Clock Time and Local Sidereal Time are to
" be given for every observation."

The carrying out of this change, though in its main feature it is a very
large diminution of the matter prepared for 'press, yet, as it consisted of
sometimes extracting numbers, sometimes taking the means of numbers,
always requiring numerous references to the originals and to the first
calculations founded on them, has in reality employed much of my time.
It has, indeed, occupied all the hours, not engaged on routine business, on
which I could usually have reckoned for other matters of science.

In regard to the form in which the Results are to be presented to the
reader, I have thought it best to leave the reduced observations in the state
in which he will find them near the end of each Part. I have endeavoured to
give the Equations in the shape which will admit of combination in the
easiest way for the computer's further operations — (whether he may desire to
use the Calculus of Probabilities for the whole, or to make any special
selection of combinations) — when he shall have decided on the recorded
phase of contact of limbs which he thinks best to adopt. The numerical
value of the first term of each Equation (on which all depends) will be
adapted to any time differing from that which I have used, by merely
expressing numerically in seconds that difference of time, and substituting it
for the symbol 8 t.

In regard to the photographs, of which I have given, in the Appendix to
this work, a general account, with sufficient details on the instruments

viii TRANSIT OF VENUS, 1874.

employed for their treatment, I conceive it to be possible that some astro-
nomer may yet think them worthy of rediscussion. The photographs
themselves are carefully preserved at the Eoyal Observatory. I do not
imagine that any important improvement can be made in their measures ;
but perhaps - the number of photographs may be reduced by judicious
rejection of those whose definition is doubtful. And the theory of instru-
mental distortion, to which I have alluded in the Appendix to this work, may
be considered.

It was recognized in some of the photographs that the limb of Venus was
much distorted by atmospheric action ; a corresponding distortion might be
expected in the Sun's limb. And it was believed by some of the measurers
of the photographs that irregularities of the Sun's limb, amounting to two
or three seconds, produced uncertainty in the measures of the photographs :
if that irregularity be real, it might be expected also to produce error on the
same scale in the optical observations of contact.

G. B. AIRY.

Royal Observatory, Greenwich,
1881, June 6.

TRANSIT OF VENUS, 1874.

PART I.

EXPEDITION

TO THE

HAWAIIAN (SANDWICH) ISLANDS,

UNDER

CAPTAIN G. L. TTJPMAN,

ROYAL MARINE ARTILLERY.

SECTION I.

OBSERVATIONS AT HONOLULU (OAHU).
With Eive Plates.

SECTION II.

OBSERVATIONS AT KAILUA (HAWAII).
With One Plate.

SECTION III.

OBSERVATIONS AT WAIMEA (KAUAI).
With One Plate.

Q 171. Wt. 17091.

TRANSIT OF VENUS, 1874.

PART I.

EXPEDITION TO THE HAWAIIAN (SANDWICH) ISLANDS.

Section 1.

OBSERVATIONS AT HONOLULU (OAHU),

/•

With Five Plates.

TRANSIT OF VENUS, 1874.

PART I.

EXPEDITION TO THE HAWAIIAN (SANDWICH) ISLANDS.

SECTION I.— HONOLULU.

I'agc-
VOYAGE, PERSONNEL, SITE, INSTRUMENTS, AND GEOGRAPHICAL DETERMINATIONS : —

Voyage and Establishment at Honolulu 5

Personnel 6

Site 7

The Transit Clock and Transit Instrument . ~ . . 9

Equatorial Intervals and Error of Level 11

Error of Collimation 12

Error of Azimuth and Meridian Mark .',.'..... 13

Transits of Stars and of the Moon . . , .•.,-.' . .• , . . . . . 15

Relative Personal Equations 16

Adopted Errors and Rates of the Transit Clock . . . , „ . ...... . . 17

The Altazimuth Instrument ,...,•«..'.... 18

Intervals of Wires ...... 19

Runs of Micrometers, and Position of the Altazimuth Pier .... 4 .... 2O

The Altazimuth Clock . . . _ . . . . • . 20

Latitude of the Altazimuth Pier . • . . ' . ; . . . 20

Observations for Co-latitude, Refractions, Zenith Points . . . . i ... , 21

Summary of Co-latitudes . . . 22

Longitude of the Station at Apua •. . • 22

Longitude from Meridional Transits of the Moon . . . . ^ , . • . .... . 22

Summary of Meridional Results ............ 23

Longitude from Observed Zenith Distances of the Moon -. 24

Summary of Results from Zenith Distances . . . .... » . » . . . . 27

Longitude from Occultations of Stars by the Moon 27

Comparisons of Chronometers, and Observations of Occultations ...;.... 2S

Calculation of Longitude from Occultations 29

Summary of Results for Longitude, from all sources . . ' 30

CHRONOMETRIC CONNECTIONS WITH KAILUA (HAWAII OR OWHYHEE), WITH WAIMEA

(KAUAI OR ATOOI), AND WITH SAN FRANCISCO (CALIFORNIA) : —

List of Chronometers 31

Detail of Voyages with the Chronometers ..-.'." .'"V" 32

Results for Difference of Longitude, and Personal Equations . . .;..'.,. . . 35

For Honolulu and Kailua . . . . . . J . . 35

For Honolulu and Waimea 35

Detail of Voyage to San Francisco, and Mode of Observation ,. . ... ., . . ^ . , 3t>

Result derived from San Francisco ..'.'. 37

OBSERVATION AT HONOLULU OF THE INGRESS OF VENUS, 1874, DECEMBER 8.

REPORT OF CAPTAIN G. L. TUPMAN, R.M.A. : —

Personal Arrangements, and Telescopes '. • . 38

Reflection Eye-pieces, and Double-image Micrometers 39

Clock, Arrangement of Spectroscope for the Observation of External Contact ... 40

Observation of commencement of Ingress, Measures of Cusps 41

Measures of Venus' Diameter, and of Cusps before Internal Contact 42

A 2

4 INDEX.

Page
REPORT OF CAPTAIN G. L. TUPMAN, R.M.A. — continued.

Observation of Internal Contact 43

Measures of Distance between Limbs of Sun and Venus 45

Comparison of Clocks 46

Discussion of the Measures made with Double-image Micrometer 47

Equations given by those Measures 49

Values of Screw-revolutions, and Semidiameter of Venus ,54

Final Equations from all the Observations at Honolulu 55

Description of the Model made to imitate the Transit of Venus 56

Comparison of Contact-times with Result of Cusp-measures, on the Model 57

REPORT OF MR. J. W. NICHOL : —

First Contact of Limbs, and Micrometer-measures of Cusps 59

Diameter of Venus, Internal Contact, and Measures of Interval between Limbs ... 61

Comparison of Chronometer ,, . . 62

REPORT OF LIEUT. E. J. W. NOBLE, R.M.A. : —

Observation of Contacts of Limbs, and Resulting Equation 63

REPORT OF MR. FLITNER : —

Comparison of Chronometer, and Observation of Contacts • . .

Resulting Equation 65

MERIDIONAL AND ALTAZIMUTH OBSERVATIONS AT HONOLULU, IN TABULAR ARRANGE-
MENT : —

Table I. — Level Error of the Transit Instrument at Honolulu

Table II. — Collimation of the Transit Instrument

Table III. — Azimuth Error of the Transit Instrument 74

Table IV. — Meridional Transits 86

Table V.— Errors and Rates of the Transit Clock 108

Table VI Comparisons of the Altazimuth Clock with the Transit Clock 113

Table VII. — Mean Places of Stars observed with the Altazimuth 119

Table VIII. — Observations, with the Altazimuth, of Collimator for Zenith Point, and of

Stars for Co-latitude 122

Table IX. — Vertical Transits of the Moon and Stars, and Longitude deduced from each . 138

Table X. — Abstract of Longitude from observed Transits of the Moon over the Meridian 190

Table XI. — Abstract of Longitude from observed Zenith Distances of the Moon . . . 192

Table XII.— Comparisons and Errors of Portable Chronometers 194

Table XIII. — Specimen of Comparison of the Portable Chronometers with the Ship

Chronometers 197

Table XIV. — Abstract of Errors of Travelling Chronometers on Local Mean Time . . 198
Table XV. — Rates of Ship Chronometers, and Deduced Differences of Longitude in the

Sandwich (Hawaiian) Group . 203

Table XVI. — Specimen of the Reflecting Circle Observations of the Sun at Honolulu . 206

Table XVII. — Errors of Ship Chronometers at Honolulu before sailing for San Francisco 207
Table XVIII. — Errors of Ship Chronometers at Mare Island, San Francisco, after the

Voyage from Honolulu 209

Table XIX. — Chronometric Difference of Longitude between Honolulu and Mare Island,

San Francisco ; and Longitude of Honolulu thence deduced .... 210

Plate I. — Plan of a portion of Honolulu 7

Plate II. — Plan of the Station at Apua »"..''.".

Plate III. — Arrangement of the Double-image Micrometer . 39

Plate IV. — Diagrams illustrating the Internal Contact at Ingress 43

Plate V.— The Model , .... 4 56

TRANSIT OP VENUS, 1874. HONOLULU.

VOYAGE, AND ESTABLISHMENT AT HONOLULU.

1. The Expedition destined for the Hawaiian Islands left England in two
detachments on board the Pacific Steam Navigation Company's steamships
Illimani and Britannia, starting from Liverpool 1874, June 3 and June 17
respectively, and proceeding by way of the Straits of Magellan to Valparaiso.
At the latter port, H.M.S. Scout, Captain R. P. CATOR, R.N., by the orders of
Vice- Admiral the Hon. Arthur Cochrane, C.B., was awaiting their arrival,
and, having transhipped the baggage, she sailed on the 4th August with all
the Expedition, and arrived at Honolulu September 9.

2. The time occupied by the long voyage was usefully employed in
preparing auxiliary tables to facilitate the reduction of time and other
observations on the spot. Thus the Apparent Right Ascensions of all the
Greenwich Clock Stars not included in the Nautical Almanac Fundamental
Catalogue for 1874 were computed for intervals of 10 days between the dates
likely to be required.

3. An elaborate set of meteorological instruments having been lent to
the Expedition from the Meteorological Office in London by the Director,
R. H. SCOTT, Esq., an accurate journal was kept during the voyage, in which
the state of the instruments, weather, &c. was recorded every four hours.*

4. On arrival at Honolulu the Expedition was most cordially welcomed by
His Majesty King KALAKAUA, and by the Ministers of State. The Expedition
was greatly indebted to His Excellency Mr. W. L. GREEN, Minister of Foreign
Affairs, and to Major James Hay WODEHOUSE, Her Britannic Majesty's Com-
missioner, who, from first to last, exhibited great interest in and materially
aided all the operations.

5. A good site was obtained without difficulty, through the active co-
operation of Captain Daniel SMITH, the harbour master.

His Majesty the KING placed at the disposal of the Expedition, rent free, a
suitable piece of open land in the southern extreme of the town. To enable
the party to be lodged conveniently near their instruments, H.R.H. the

* It may be stated here that the Meteorological Journal was continued during the stay of the
Expedition at Honolulu, and has since been deposited at the Meteorological Office, Victoria Street,
Westminster.

(> TRANSIT OF VENUS, 1874. HONOLULU.

Princess RUTH, at the suggestion of Governor DOMINIS, of Oahu, considerately
vacated her own house, known as HONUAKAHA HALK, and allowed it to be
rented on liberal terms.

6. It is difficult to do justice to the exertions of Captain R. P. CATOR, R.N.,
of H.M.S. Scout, who remained at Honolulu until the middle of December,
and of Commander VAN der MEULEN, R.N., of H.M.S. Tenedos, to whose
careful forethought and continual personal superintendence the success of
the Expedition was in no small degree due. After the tedious operations
of transporting the chronometers backwards and forwai'ds to the Islands of
Hawaii and Kauai, the Tenedos was succeeded by H.M.S. Reindeer, Commander
C. V. ANSON, by whose cordial co-operation the outlying parties were brought
back to Honolulu, and the Expedition finally taken to San Francisco on its
way home.

7. Mr. David FLITNER, of Honolulu, who himself successfully observed the
Ingress of Venus at Waiakiki, most generously lent a number of marine
chronometers to assist in the longitude operations. Captain D. SMITH also
lent a chronometer for the same purpose.

8. I cannot close these remarks without recording the friendly welcome
accorded to the members of the Expedition by the American and British
communities of Honolulu. It would be invidious to mention a few names
when all were so kind and hospitable that the reminiscences of our six
months' sojourn on that far distant island will ever be of the most agreeable.

PERSONNEL.

9. The observing party at Honolulu consisted of Lieutenant F. E. RAMSDEN,
R.N., who undertook the management of the Photographic Department,
and also assisted in astronomical observations ; Lieutenant (now Captain)
E. J. W. NOBLE, R.M.A. ; J. W. NICHOL, Esq.,* F.R.A.S., formerly assistant
at the Royal Observatory, Edinburgh ; and myself. In the following pages
these observers are distinguished by the letters R., No., Ni., and T. respectively.

10. There were also attached to the Expedition Lance- Corporal CURRY and
Sappers M. MEINS and J. MYERS, Royal Ens/Mieers, who rendered most effective
assistance generally, and in the Photographic Department especially, and
voluntarily kept the four-hourly Meteorological Register during our stay at
Honolulu.

* Mr. Nichol died in November 1878.

Transit of Venus 1814. Dec. 8.

Plate I.

Pla-n- of a, portion of Honolulu- shewing the position, of tht Transit ofVeniM Station,
Trie smaller plan, slwws tfie position/ of tJi& Statum, with regard to tht principal
points of the Gwerrunent Trdgcncrnetrical Survey.

Scale of English Feet.

P 5000 10000 I5OOO

References. A. a point 14 -15 feet South of the. Centre of the- Transit pier cut-
SB. Base line of the Government/ Trigonometrical Surrey.
D . Trig. Statwn on Diamond- Head- fLuth^J
K. , , Mount Konahuanui-

L . , . , Light house

P. , „ ,. funch-bowl

T . „ Mount Tantalus (Punshia/J

W. VdlageofWaiakiM,.

I:TH 22 BED'OIC Sr COVLT C«not«.

To face page 7.

POSITION OF THE STATION AT HONOLULU.

THE SITE AT HONOLULU. — Plates I. and II.

11. The open piece of grass land in the district called Apua is situated
south of Punchbowl Street and west of Queen Street. A portion, in every
way suitable for our purpose, was enclosed with a wooden fence, and the
instruments, &c. were there set up, as represented in Plate II. The actual
site of the Transit Pier was 300 feet from the centre of Punchbowl Street,
420 feet from Queen Street, 910 feet from the flagstaff on the New
Government Buildings, and 1,040 feet from the spire of Kawaiahao (stone)
Church.

12. From a point 14'75 feet due south of the centre of the Transit Pier the
following true bearings and distances were taken, to determine the relative
positions of the instruments, and to connect the station with the Government
Trigonometrical Survey : —

o /

Spire of Kawaiahao Church N. 62. o E. i,O4O± feet.

Trig. Survey Station on Punchbowl Hill N. 49. 44 E. 0,104 »

„ ., „ Mount Tantalus N. 55. 26 E.

„ „ „ Diamond Head S. 46. 32 E.

Center of Photoheliograph Pier N. 76. 3o E. 28 • 5 feet.

„ Altazimuth Pier S. 86. 5y E. io3'o .,

„ -1 .V-int'h Equatorial S. 5g. g E. 35 'o .,

„ 6-inch „ S. 5z. 27 E. yo'o ,,

13. In or about the year 1845 Professor LYMAN, now of Yale College,
Connecticut, then residing in Honolulu for the benefit of his health, made a
number of meridional observations of the Moon in order to determine the
longitude. It is supposed that these observations have never been published,
but their utility was such that in 1874 the Hawaiian Surveyor-General was
still using the longitude communicated to him by Professor Lyman. The
observatory and transit instrument of Professor Lyman passed into the
hands of DAVID FLITNER, Esq., chronometer maker, of Honolulu, and in 1874
they were in perfect order. The position of the observatory is shown in
Plate I.

14. In the year 1868 M. FLEURIAIS, deputed by the Bureau dcs Loiigitudes to
determine the longitudes of various points in South America, established
himself at Honolulu. With the friendly assistance of M. BAILLIEU, Commis-
sioner for France, the actual site of M. Fleuriais' Observatory was recovered
through some remains of the masonry of the Transit Pier which were found
in situ en the coral rock, five feet below the surface of the road, by the

8

TRANSIT OF VENUS, 1874. HONOLULU.

workman who had built and who had afterwards removed the brickwork.*
It was situated on the north side of Emma Street, immediately opposite to
the end of Adam's Lane.

15. At my request, Mr. J. N. G-AY, surveyor, of Honolulu, kindly made the
following traverse with a 5-inch theodolite and 66-foot chain, to connect the
station at Apua with the observatories of MM. FLEURIAIS and FLITNER.

Theodolite Stations.

" • TrueAzhnuth. £££$£.

A to Bf

North.

14-75

In the direction of the North

B to C

North.

295-5

Meridian Mark.

C to D

N. 76°. 40'. E.

261 •

D to E

N. 38°. 34'. W.

g5o"

D to Z, N. o°. 37'. W.

E to F

N. 55°. 38'. E.

iz5i '5

E to Z, S. 68°. 32'. E.

F to G

N. 55?. 34'. W.

8g3'5

Gto H

N.4i°.57'.E.

79'

G to I

N. 60°. 41'. E.

320'

I to K

N. 88°. 3o'. E.

217-5

K to L

N. 88°. 3o'. E.

341 '

L to M

S. 3o°.4i'. E.

498-

Mto N

S. 54°. 3i'. W.

459*5

N to O

S. 37°. iS'.E.

961-5

O to P

S. 48°. 21'. E.

55g-5

P to D

Not observed.

648-

A. Position of Mr. Gay's theodolite within the enclosure at Apua.

B. The center of the transit pier.

H. The center of Mr. Flitner's transit pier.

K. M. Fleuriais' transit pier (restored).

Z. The flagstaff on the Government Buildings.

16. From the above, M. Fleuriais' pier was 2,474 feet north and 456 feet
east, and Mr. Flitner's pier was 2,370 feet north and 12^ feet east of the
center of the transit pier at APUA (see the section Longitude of Honolulu).

17. A stage was erected near the southern angle of the enclosure to carry the
telescopes used for observing the model. "Water was laid on from the main in
Punchbowl Street. There were two taps on which to attach hoses in case of
fire (the fire buckets and tubs were always kept filled), and three other taps
for photographic and other purposes. Corporal Currie, Sappers Meins and
Myers, R.E., lived on the premises, and the observers' residence, Honuakaha
Hale, was about 130 yards distant on the other side of Punchbowl Street.

* To preserve this site I erected a small brick pier, the top of which was left about one foot
below the surface of the road.

•j- The lines of the traverse are shown in Plate I. by a dotted line. The reader, following the
Azimuths given above, will without difficulty identify the points B, C, D, &c.

Plate 11.

Transit of Venus, 1874 December 8.

Flan of the Observing - Stativw at Apua , Honolulu,.

Latitude of the Altazimuth Pier 21:17.56.9 Noj-th; Longitude 10^ 20™ 16s 3 West

of Greenwich.

a 4jinch, \Equatjireal

Water*

0> inch. Equatoreal

A Oj Atiagunuth

PlatJbrrn for observing the Model
of the Transit of \%nu£, distant
800 Feet.

Scale of English, Feet,.

. 0 K> JO 30 40 £0 60 7O .SO 90 100

Illllllllll 1 1 1 1 1 I I | i 1

To face page, 8.

DANCCRFIELU LITH 22 BCOFORD ST COVCNT CAKOEN

TRANSIT INSTRUMENT. 9

18. In this part of the town the coral is covered by some four feet of
very light sandy soil. Although high-water mark was half a mile distant,
the tide percolated through the coral and rose many inches above its
surface, but in no way interfered with the stability of the piers, which were
set with cement.

THE TRANSIT CLOCK.

19. This was constructed by Messrs. B. Dent and Co., of London, in 1870,
and was numbered 1916. The compensation of the pendulum was effected
by their well-known cylindrical combination of zinc and steel. The clock, in
common with all the clocks employed on the Transit of Venus Expeditions, was
tested for a long time at the Royal Observatory, Greenwich, under very trying
variations of temperature, and its performance was excellent. At Honolulu
it was mounted on a massive tripod of mahogany and iron, which rested upon
three stakes driven 2 or 3 feet into the ground. It was wound every Sunday
at noon. The suspension spring of the pendulum was changed, 1874,
November 7, after which the rate was remarkably steady (Tab. V.).

THE TRANSIT INSTRUMENT.

20. Five transit instruments, precisely similar in all respects, were con-
structed for the Expeditions by Messrs. Troughton and Simms. One of these
was used at Honolulu. The object glass was very nearly 3 inches clear aperture
and 36^ inches focal length. The axis, consisting of central cube and cones,
was cast in one piece. Its length from shoulder to shoulder (that is,
exclusive of the pivots,) was 18 inches ; the pivots were 1| inches long and
1^ inches diameter. The cube was of 6 inches side ; the cones were
5^ inches in diameter at the cube and 2| inches at the shoulder. The two
tubes which, with the cube, formed the telescope, were 4^ inches in diameter
at their attachment (by flanges) with the cube. When the dew cap was on,
the instrument weighed 44 Ibs., and was perfectly balanced on its pivots.

21. The system of webs, consisting of 5 vertical webs, at intervals of about
3^', and two horizontal webs, about 5' apart, was mounted on the plate driven
by the micrometer screw, so that the whole system moved when the screw
was turned. The head of the micrometer screw was divided on silver to
100 parts, and was provided with a movable brass cover to prevent it being
accidentally turned when not actually in use, as when observing time-stars.
The thread of the screw was kept bearing in one direction by a spiral spring

B

10 TRANSIT OF VENUS, 1874. HONOLULU.

within the box, as with all Messrs. Troughton and Simms' micrometers.
There was no perceptible " loss of time " in any one of them. The eye-piece
was moved rapidly from wire to wire by a quick screw, the milled head of
which was opposite to the micrometer-screw-head. The illumination of the
wires was effected in the usual way by lamp-light passing through one of
the pivots on to a gilt reflector, regulated by a rod leading down to the
eye-piece. There was a polar distance setting circle 4^ inches diameter
on each side of the tube near the eye end.

22. A solid pier of brick and cement, 6^ feet by 3^ feet at the top and
somewhat larger at the bottom, was built up from the coral (previously
levelled) to about the surface of the ground. On this was laid, levelled,
oriented, and cemented a great stone, 6 feet by 3 feet and 6 inches thick,
weighing 1,500 Ibs. After the cement had well set, the stone piers were
placed in position. These piers were 4 feet 11 inches high, 24 inches by 21 at
the base, and 11 inches square at the top, and weighed nearly 1,400 Ibs. each.*
The Y's were of massive construction, one having an adjustment for azimuth
the other for level. They were attached to the tops of the piers "by heavy
sockets cemented into the stone. The supporting faces of the Y's were
inclined 90°, and were rounded so as to touch a very small surface of the
pivots. When the instrument was thus mounted, a heavy blow with the fist
administered to the top of one of the piers merely produced a momentary
tremor of the optical image of a distant object.

23. The instrument was provided with three eye-pieces of powers 45, 75,
and 120. The power of 75 was always used at Honolulu. A small prism of
total reflection could be attached to the eye-piece for the more convenient
observation of stars near the zenith. The shape of the piers left plenty of
room for the observer to sit between them.

24. For determining the level-error, the instrument was fitted with a
Bohnenberger eye-piece and mercury trough, and with a hanging level of
delicate construction graduated with about 12 divisions to each inch, 46 of
which were equivalent to one minute of arc. The divisions were numbered
from 0 to 100, the readings increasing towards the cross-level. The glass
bubble itself was protected by a covering of plate glass. The value of the
graduations was re- determined by the makers just before the expedition
started, several years after the instruments were made.

* Three great stones similar to these, forming the mounting of the transit instrument, and the
wooden observatory, 13 feet square, were sent out from England with each expedition.

TRANSIT INSTRUMENT. 11

25. TJte equatorial intervals of the wires were determined from 500 transits
of clock stars, and 32 transits of close circumpolar stars. No accident
happened to the wires during the four months of observations. The wires
were named a, b, c, d, e, the wire a being farthest from the micrometer-screw-
head. The equatorial intervals finally adopted were —

a = -f- 28-483")
b = + 14-413 |
c = o'ooo )> For micrometer east.

d= — 14-384
« = — 28-426J

Consequently, to reduce the mean of the five wires to the center wire, the

o9 * o 1 60
correction, with micrometer east, is + s;n KPD • stars within 30° of

the equator this correction has been taken as = + Os-02 (micrometer E.)

26. TJie value of one revolution of the micrometer screw was obtained from
very numerous observations of close circumpolar stars, chiefly of Polaris. (^
Altogether there were made 64 separate determinations at different parts of

the screw, each obtained from at least five bisections, all tending to show
that there was no sensible drunkenness or error periodical on one revolution.
The adopted value is 56"-251.

The integer revolutions of the screw were read from a comb in the field
of view by means of the center wire ; they were numbered in the observation-
book so that the 20th revolution (20r-000) occupied the optical center as
nearly as possible, with increasing readings towards the head. Thus 22r>000
signifies that the system of wires was moved two revolutions from its central
position towards the micrometer-screw-head.

27. The Error of Level of the transit axis was generally determined, with
the hanging spirit-level described above, once or twice with every batch of
time stars and with every circumpolar star observed for azimuth error. The
relative position of the pivots, both in level and in azimuth, was subject to a
regular diurnal variation. During the night the east pivot sank from 2" to 3",
and moved to the north about the same amount. The adjusting screws were
touched on 1874, October 5, after which date the level-error remained small
and steady. Several shocks of an earthquake on 1874, December 28, pro-
duced no sensible alteration in the position of the instrument.

28. The correction to the level-error, as found by spirit-level, for inequality
of the diameters of the pivots, was found, by repeated reversions of the
instrument, to be on —

c

12 TRANSIT OF VENUS, 1874. HONOLULU.

//

1874, October 2, +0*042 with micrometer west.

,, i5, +0-047 » »

November 20, +o'o85 ,, ,,

,, +o-o52 ,, ,,

The adopted correction for inequality of pivots is +0"'06 micrometer west.
The observed level-errors are given in Table I. The level-error adopted in
the reductions for a group of stars has always been the mean of the deter-
minations, by the same observer, accompanying the group.

29. The Error of Gollimation of the transit instrument. There is no doubt
that, during the long outward voyage, the ring clamp, on which the rigidity
of the connection between the system of wires and the body of the instrument
depended, became slightly loose, and that this escaped detection until
November 6. Two or three times, during the month of October, parts of the
eye-end connected with the micrometer were removed under the impression
that they caused the uncertainty in the position of the optic axis. On
November 6 the ring clamp above mentioned was tightened, after which
there was no further trouble.

30. At first the collimation-error was determined by observing a close
circumpolar star with reversed positions of the transit-axis. A few minutes
before the star came to the meridian, the observer removed the brass cover of
the micrometer-screw-head, set the center wire to some quarter of a revolution,
and allowed the star to transit the center wire. The micrometer was then
turned a quarter of a revolution or other known quantity, and another transit
of the center wire observed. Five or six such observations were taken before
the star came to the meridian ; the instrument was then reversed, and the
star observed in transit over the center wire with the micrometer successively
set to the same readings as before, but of course in reverse order. The
level-errors for these two sets of observations should differ by twice the
inequality of pivots ; but generally the level-error was determined before
and after, and applied as found.

31. On 1874, October 5, a stout post with a T cross head was set up on
the north side of the transit-hut, to support a telescope of 30 inches focal
length with cross webs in the focus of the object glass. The post was
entirely protected from the direct rays of the sun by screens of rushes. The
observations of this collimator were generally made at night. The transit
instrument was always reversed twice because the collimator was not always
perfectly steady. After November 4 the meridian mark was more generally

TRANSIT INSTRUMENT. MERIDIAN MARK. 13

used. The mark (or the cross of the collimator) was bisected five or six
times with the center wire. The observations of the meridian mark are
given in Table III.

32. As the whole system of wires moved with the micrometer-screw, the
error of collimation is always the difference between the actual reading of
the micrometer and the reading which corresponds to zero, or when the
center wire coincides with the optic axis. If M be the former, Z the latter,
and R the value of one revolution, the collimation-error in arc is given with
its proper sign for micrometer east by .the formula —

+ (Z - M) R.

The readings for Z as determined by observation are shown in Table II.
The adopted reading and M are given each day with the transits of stars.

33. The Azimuth-Error of the transit instrument was found in the usual
way by combining observations of Polaris, 8 Ursae Minoris, Cephei (Hev.) 51,
or x Ursa? Minoris, with those of clock stars. Some difficulty was experienced
in setting up a meridian mark at a proper distance. To the south the sea-
shore was too near ; to the north there was no choice ; the crest of a range
of hills four miles distant, and very difficult of access, was the only available
place. On November 4 Mr. Nichol, accompanied by Mr. C. J. Lyons, of the
Government Survey, who was well acquainted with the country, with a party
of native workmen, ascended the mountain to the height of 1,540 feet, and
erected the mark exactly on the crest of the hill, so that it showed out in
bold relief against the sky at an altitude of 3° 40'. The mark itself consisted
principally of two vertical posts of timber, 16 feet long and 4 inches by 3 in
section, planted with 4r| feet of their length in a stiff red clay, and shored
up with four stout stays. The clear space between the inner surfaces of
the posts was 9 '94 inches, and subtended 8" '05 as seen from the transit
instrument ; its center was afterwards found to be about 10 inches east of
true north, and to be 21,218 feet from the transit instrument.

34. The mark was observed for azimuth-error, after sunset, and as early as
possible every morning, the center wire being placed by estimation centrally
between the two posts. These observations showed a nearly regular diurnal
movement of the optic-axis in azimuth of about 3", the telescope pointing
more east in the morning than in the evening. It was never possible to
observe the mark during the heat of the day. In order to determine the
absolute azimuth of the mark and the law of the azimuthal change of position
of the instrument, the mark was illuminated through a hole in the center,

c 2

14 TRANSIT OF VENUS, 1874. HONOLULU.

4 feet from the ground, from sunset to sunrise on the nights of 1875,
February 6, 7, 8, and 9, and its image bisected with the micrometer every
half hour. The hanging level, which was left in position and reversed only
occasionally, was read at the same time ; while as many circumpolar stars as
possible were observed.

The results of the four nights' observations showed that the direction of
the optic axis moved steadily to the eastward (when the telescope was pointed
to the north) from sunset until llh. 30™ mean time. It then remained steady
until sunrise. The observations of the mark corrected for level-error, com-
pared with the stars, give the following absolute azimuths of the center of

the mark from the center of the transit instrument : —

//

1 876, February 6, S Ursas Minoris 9 • 66 east of north.

Cephei 5i 7 ' 85

, , 7,8 Ursas Minoris 6 • g5

Cephei 5i 8'i3

X Ursae Minoris 7 • 88

Polaris S.P 7-11

, , 8, 8 Ursse Minoris 9 '20

X Ursse Minoris 8 • 53

Polaris S.P 7-67

, , g, 8 Ursas Minoris 8 " I o

Cephei 5i 8' 85

X Ursas Minoris 9*44

Polaris S.P 8' 88

The adopted absolute azimuth is 8" -32.

35. On 19 mornings there 'are observations of Polar Stars not very long
before the mark was observed. Assuming that the instrument was steady in
azimuth after midnight, each of these gives a determination of the absolute
azimuth of the mark. The mean of them is 8"'23.

36. The azimuth-error adopted in the reductions for a group of stars has
been found in the following manner: — If the middle time of the group is
later than llh. 30m mean time, a mean has been taken of the azimuth-errors
found from circumpolar stars and the morning observation of the meridian
mark. For example, on 1874, November 22, Table III., there are four
determinations of the Error of Azimuth after midnight (three by circum-
polar stars, one by the meridian-mark), the mean of which has been used
in reducing the group of clock stars observed after midnight. When
tne middle time of the group falls before llh. 30m mean time, it has been
assumed that the change of azimuth, denoted by the difference between the

REDUCTION OF OBSERVED TRANSITS. 15

evening and morning observations of the mark, took place with uniformity
between the evening reading and llh. 30m mean time. If the mark has not
been observed in the morning, the mean change 2"-5 has been used, and a
proportional part applied to the evening observation of the mark. This
azimuth-error has then been combined with those obtained from circumpolar
stars. For example, on November 13, Table III., the difference of azimuth
by the evening and morning readings of the mark is 3"-37. Clock stars were
observed at about 10h, that is, four hours after the observation of the mark.
It is assumed that a change of 2"-45 took place in those four hours, and that,
therefore, the azimuth-error by the mark was — 0"'92. The error used for
the group is the mean between this and — 0"'72 found by Polaris at 9h. 40m.

Table III. contains the whole of the determinations of azimuth-error and
the observations of the meridian mark.

TRANSITS OF STARS AND OF THE MOON OBSERVED AT HONOLULU, AND DEDUCED
ERROR OF THE TRANSIT-CLOCK DENT 1916.

37. The stars observed for clock-error were taken from the catalogue of
clock stars in use at the Koyal Observatory, Greenwich. The Mean Right
Ascensions were brought up to the beginning of the year from the Greenwich
Catalogue of 2760 Stars, Epoch 1864, and are identical with those adopted at
the Royal Observatory. For those stars found in the Nautical Almanac the
apparent places have been taken from that work, a small constant correction
being applied to reduce them to the standard of the 1864 Catalogue. The
Moon Culminating Stars, for which good places have not been recently
obtained, have been rejected. The Apparent Right Ascensions of such stars
of the Greenwich list as were not in the Nautical Almanac were brought up,
during the outward voyage, for every ten days of the period during which
they were likely to be required.

38. In reducing the observed transits of clock stars the mean of the five
wires has been, for convenience, reduced to the center wire by the correction
O-02, additive when the micrometer was east. The diurnal aberration has
been taken as follows : —

a

For Polaris o • 80

, , 8 Ursas Minoris o'oz

, , Cephei 5i °'4°

, , X UrsJB Minoris i • o3

, , all the Clock Stars o • 02

These quantities have been applied to the Apparent Right Ascensions
throughout.

16 TRANSIT OF VENUS, 1874. HONOLULU.

39. For the convenient application of the corrections for level, collimation,
and azimuth, a table of factors was computed for every degree of N.P.D.,
similar to that contained in the Introduction to the Greenwich Observations.
Similar factors were computed for the four azimuth-stars for every 15 days.
Tor the more accurate reduction of circumpolar stars observed rather far
from the meridian, and of imperfect transits of clock stars, the collimation
factors were computed to four places of decimals. The observations of
circumpolar stars more than eight minutes of time from the meridian have
been reduced by the rigorous formula.

40. The clock-correction was required for (1) the transit of the Moon ;
(2) the Altazimuth observation of the Moon ; (3) the comparisons of travel-
ling chronometers ; and (4) for latitude observations. No night was allowed
to pass without the clock and instrumental errors being determined, if
possible ; and a sufficient number of observations were made to obtain the
relative personal equations of the observers ; which was necessary, because
the observation of the Moon with the Altazimuth was too fatiguing to admit
of many stars being taken by the same observer.

41. The observed Transits of the Moon and Stars, as arranged in Table IV.,
require little explanation. The day commences at noon, 10h. 31m later than
noon at Greenwich. The reading and position of the micrometer are given
(in the third column) for every star, it being understood that a given reading
is to be carried down the column until a change occurs'. In this column the
adopted reading for zero of collimation for the day is also given in a bracket,
thus [20'070]. It generally applies to all the observations made in one night,
but occasionally different values have been used for different observers. When a
circumpolar star has been observed with reversed positions of the transit-axis,
the two observations are separately reduced. The clock correction proper to
apply to the true transit of the Moon's limb is entered in the eighth column
in a bracket, thus [2O86], on October 17, Table IV.

42. It has been considered, sufficient to print in detail the transits of the
stars observed with the Moon, and those observed for azimuth-error on the
days when the Moon was observed with the Altazimuth. All other transits
are omitted. Each observer's mean result for clock error is given in Table V.

43. Determination of tlie relative personal equation in observing transits of stars
of the observers at Honolulu.

In the following table T — R = +0S'22 signifies that T makes the clock
Os-22 more slow than does R. The numbers are obtained from Table V. by
interpolation.

PERSONAL EQUATIONS. ERRORS AND RATES OF TRANSIT CLOCK.

17

T- No

T - R

No - K

s

s

s

1874, Oct. g — -14

1874, Oct. 8 + -08

1874, Oct. 9 + -32

21 — 'l5

9 -T--I8

20 — '07

22 + 'l6

17 +-io

22 + MO

Nov. 1 3 + -08

22 + '26

24 + '09

23 + '08

Nov. 8 + -12

25 — '14

27 + -07

12 + '26

26 + -07

28 — -oj

16 +-II

27 + -i3

Dec. i — -o5

23 +-I7

Nov. 9 + -19

3 — -06

27 +-14

14 + -io

8 — -04

28 + -34

i5 + -24

29 + 'o3

2g 4- '22

23 + -09

1876, Jan. i + -o5

Dec. i3 + -26

27 -f -07

26 •+• '04

1876, Jan. 2 + -3z

28 + -35

28 + -02

4 + 'i6

3o + 'ig

3o + -04

6 + -20

Dec. 4 — -02

8 + -19

5 + '20

9 +-'4

7 + -20

10 + '24

9 + -20

11 + '22

io + "3i

i3 + -i5

II + -18

27 + -29

1 5 + '09

29 + -20

16 — -06

17 +-io

29 + -38

3o + -2i

1876, Jan. 23 + '06

The adopted personal equations are —
Until 1874, December 17, inclusive, —

After December 17, —

T =

•oo

No =

•oo

R =

+ -16

T =

•oo

No =

+ '04

R =

+ '22

44. The Adopted Errors and Rates of the Transit Clock are shown in Table V.
The mean of each observer's group (omitting, of course, the circumpolar
stare) is taken and corrected for personal equation, and the mean for the
night is then found. The loss in 24 hours corresponds to the middle time
between the times for which the error is adopted. The adopted rate cor-
responds to the time for which the error is adopted. This adopted rate has
only been used during the six hours preceding and following the time to
which it corresponds. At other times the " loss in 24 hours " has been used

18 TRANSIT OF VENUS, 1874. HONOLULU.

as the rate. The clock-error proper to apply to the transit of the Moon's
limb is explained on page 23.

THE ALTAZIMUTH INSTRUMENT AND OBSERVATIONS OF ZENITH DISTANCE.

45. Three instruments for zenith distance, rotating round vertical axes
(frequently called Altazimuths, though possessing no accurate graduation in
azimuth,) precisely alike in every particular, were constructed for the expe-
ditions to Honolulu, Mokattam, and Rodriguez, by Messrs. Troughton and
Simms. Bach of these instruments had two vertical circles attached to the
horizontal axis which carried the telescope. They were 14 inches in diameter,
and were divided on silver to 5' spaces. One circle was read by four
micrometer-microscopes, supported by radial arms cast in one with the
rotating body of the instrument. One revolution of each micrometer-screw
was intended to be 60". The movable micrometer frames carried two parallel
wires of spider's web instead of the usual cross. The probable error of
bisecting a division of the circle with one microscope was something under
1". The other circle was read by the pointer on the other side of the
instrument, where also was the illuminating lamp. Two zenith-distance
levels, each divided approximately to 2", were attached to the arms which
carried the microscopes. The value of the divisions engraved on the levels
were re-determined by the makers just before the Expeditions started.

46. The horizontal axis, telescope, and circles, were built together like a
transit-circle. The object-glass had a clear aperture of 2*00 inches and focal
length of 20 inches. The reticule consisted of five horizontal and six vertical
webs, but the latter were only employed to define the middle points of the
horizontal webs. The eye-piece used for all observations was a four-glass
diagonal, power 33. The pivots were three-quarters of an inch in diameter,
and were both pierced. The circles were interchangeable, and could be
turned on their axes; but their positions were not altered during these
observations.

Circles of plate glass, parallel to and concentric with the graduated circles,
were placed outside the framework to protect the levels from the heat of the
observer's body and reading-lamp. The illuminating-lamp was on the side
opposite to the microscopes. The horizontal circle (which was only used for
setting in azimuth) was 12 inches in diameter, and was read by two verniers.
There were clamps in zenith-distance and azimuth, the former with a fine
slow-motion screw, the latter with a rather quick screw, which was turned
during a vertical transit to keep the object at the middle part of the

ALTAZIMUTH INSTRUMENT.

19

horizontal wires. For adjusting the verticality of the principal axis, two
sensitive levels were attached to the lower portion of the revolving body. A
sensitive striding level could be applied to the telescope axis, and the instrument
could be used as a portable transit by clamping it on both sides in the meridian.
The solid tripod base of the instrument stood upon three brasses let into a
thick slab of slate, which formed the head of the pier. Each instrument was
protected by a wooden hexagonal hut about eight feet in diameter, with a
revolving roof, slit, and shutter, and was accompanied by a secondary
sidereal clock with wooden pendulum rod, which was intended to be com-
pared with the transit-clock, before and after every observation, by the
intervention of a mean time half -seconds chronometer. A mercurial barometer,
an aneroid, and thermometers, were also supplied. At Honolulu the instru-
ment was supported by a solid pier of brick and concrete founded on the coral.

47. The observer first opened the hut as much as possible to let the instru-
ment take up the temperature of the external air. He then compared a mean-
time half -seconds chronometer with the Transit-clock and Altazimuth-clock by
coincidence of beats, and recorded the barometer and external thermometer.
When the observations were concluded, the clocks were again compared, this
time commencing with the Altazimuth-clock ; and the barometer and thermo-
meter again recorded.

48. When observing a vertical transit, the zenith-distance levels were read
before and after the transit, and the microscopes were read last. For a
latitude observation, in which the instrument is not, of course, moved in
azimuth, the levels were read immediately after the bisection.

49. For determining the zenith-point and intervals of the horizontal wires
independently of the stars, collimating arrangements, similar to that described
with the transit instrument, were set up on the south and east sides, and the
same reversed telescope was used. This collimator was perfectly steady in
zenith distance, and by its means the intervals of the horizontal wires from
their mean were accurately obtained as follows : —

Day.

I

Wire A.

Wire B.

Wire C.

Wire D.

Wire E.

o

//

/ //

1874, Oct. 10

NI

+ 6. 3-28

+ 3. 6-g3

+ o. 4-43

-3. 4-67

- 6. 9-97

, , Oct. 1 1

Nl

4-40

5-8o

3'io

3'5o

9-80

, , Dec. 1 8

Nl

5-22

7-32

4-12

6-38

10-28

1876, Jan. 3o

NI

3'94

6-44

3-54

4-86

9-06

, , Jan. 3 1

T

4-82

7-22

3-62

4-88

10-78

Mean adopted . .

••

+ 6. 4-33

+ 3. 674

+ o. 3-76

- 3. 4-86

— 6. 9-98

20

TRANSIT OF VENUS, 1874. HONOLULU.

The distance of the wire C from the mean of the wires was also found,
from the times of 90 vertical transits, to be -00479 of the interval from
A to E. Taking this interval at 734"'3, C is distant 3"'52 from the mean.
The value 3"'76 has been adopted, and for convenience has been applied to
the zenith point, which is always greater by this amount for transits over all
the wires than for observations with the center wire only.

50. The mean corrections for the runs of the four micrometers for 100"
were obtained as follows : —

Correction

No. of

Bay.

Observer.

for Runs for

100".

Determina-
tions.

1874, Sept. 3o

NI

//
— O'22

4

Oct. 6

NI

— O'23

4

,, 3

T

— 0'2 I

2

,, i3

NI

— 0'08

4

,, 19

NI

— O'23

4

Nov. 1 2

NI

— O'2I

4

Dec. 3

NI

— O'24

4

1875, Feb. i

NI

— o-2g

4

,, 5

T

— o-35

4

„ 5

T

— o'23

4

The mean — 0"'21 has been adopted throughout.

51. The Altazimuth pier was 103 feet east of the Transit pier, corresponding
to a difference of time of Os>074. This correction should have been applied
to the Altazimuth clock-error, but it was overlooked until the reductions had
proceeded so far that it was more convenient afterwards to apply the
necessary correction to the longitude (see page 27).

52. The Errors and Hourly Rates of the Altazimuth Clock used in reducing
the zenith-distance observations are shown in Table VI. All the comparisons
of the solar half-seconds chronometer with the two clocks were made at the
instant when the beats coincided. The clock was made by E. Dent and Co. ;
the pendulum rod was of wood. It was compared with the Transit Clock
before and after every set of observations with the Altazimuth.

THE LATITUDE OF THE ALTAZIMUTH PIER.

53. The latitude was determined with great care, with the object of serving
as a point of reference for the Trigonometrical Survey of the kingdom of
HAWAII undertaken by the Government of His Majesty King KALAKAUA, and

OBSERVATIONS FOR LATITUDE. 21

which, under the able management of Professor W. D. ALEXANDER, had
already made great progress when the Expedition visited the Islands. The
stars selected were such as had been well observed in N.P.D. either at
Greenwich, the Cape of Good Hope, Melbourne, or Oxford, and were equally
distributed north and south of the zenith of Honolulu. Table VII. contains
the adopted places of the stars and the separate determinations of N.P.D.
that have been used. For stars south of the Equator a preference has
been given to the N. P. D.'s determined at the Cape Observatory and at
Melbourne.

54. The observations for co-latitude are shown in the Table VIII. The
fourth column contains the time by the Altazimuth Clock, when the observer
bisected the star with the middle part of the center horizontal wire, by
turning the fine zenith-distance slow-motion screw. The error and rate of
the clock have been given (Table VI.). The fifth column shows the position
of the instrument, by the illuminating-lamp being on the observer's right or
left hand as he faced the star. The sixth column contains the concluded
circle-reading as obtained from the mean of the four microscopes corrected
for runs. The seventh column contains the level indication, which is one half
of the sum of four readings corresponding to the ends of the bubbles ; for
each level had 30 divisions to the minute.

The refraction in the eighth column has been computed from the Tables of
Bessel's Refractions in the Appendix to the Greenwich Observations, 1853,
and then multiplied by the factor O9947. [Mr. Stone, Monthly Notices of the
Royal Astronomical Society, 1867, November 8].

55. The Mercurial Barometer, A.2 Casella No. 352, and External Thermo-
meter were tested at the Royal Observatory, Greenwich, and were found to
have no sensible errors. The former was suspended under the thatched
covering of the East Collimator, where the temperature at night, as indicated
by the attached thermometer, was always from 1° to 2° higher than the
external air. The latter \vas attached to the north side of the Altazimuth
hut, about four feet from the ground. The readings are given in the ninth
column.

56. The observed zenith point in the tenth column is thus found : if C,, Cr
be the circle-readings for the same object, corrected for level and refraction,
with the lamp left and lamp right respectively, and rl5 ra the corresponding
reductions to the meridian, the zenith point is ^ (C, — t\ -f- Gr + r2).

The concluded zenith distance in the twelfth column is the difference

D 2

22

TRANSIT OF VENUS, 1874. HONOLULU.

between the circle-reading corrected for level and refraction and the adopted
zenith point.

The remaining columns require no explanation.

5 7 . Summary of co- latitudes.

North Stars

South Stars.

Zenith Distance.

Co-latitude.

Number
of Stars.

Co-latitude.

Number
of Stars.

North and South.

0 O

1 5 to 60
60 to 70
70 to 8 1

o / //
68.42.3-83
68. 42. 2-87
68. 42. 2-29

'9
28

10

o / //
68.42.3-26
68. 42. 2-81
68. 42. 3-24

27
7
19

0 / //

68. 42.3-54
68. 42. 2-84

68.42. 2-77

Means

68. 42. 3-09

57

68. 42.3-20

53

68. 42. 3-14

As was to be expected with so small an instrument, the flexure is insensible.
It is to be remarked that the lines of sight of the low northern stars passed
pretty closely over the summits of the mountains. The latitude derived from
these stars differs 0"-8 from the general mean. The adopted latitude of the
altazimuth pier is 21°. 17'. 56"-9 N. It is probable that the meridional devia-
tion of the plumb-line from the vertical is considerable, as the sea is deep
to the southward, and the axis of the mountain range only 4 or 5 miles to
the northward.

ON THE LONGITUDE OF THE STATION AT APUA.

(1.) Longitude of Honolulu Station from the Observations of the Moon on the

Meridian.

58. In Table IV. are given the observed transits of the Moon over the
center wire as obtained from the mean of all the wires observed. When all
five wires have been observed, the observation has been treated as if it were
of a star, the sum of the instrumental corrections always being a fraction of
a second. For the incomplete transits, of which there are five, the reduction
of each side wire to the center wire has been obtained by multiplying the
Equatorial interval by the factor —

(i + m) . sin z.
Sin d . sin z1.

where m is the increase (in seconds of time) of the Moon's R.A. for the
transit over a meridian distant 1s of terrestrial longitude, as given in the
section Moon-culminating Stars in the Nautical Almanac ; z is the Moon's

LONGITUDE FROM MERIDIONAL TRANSITS OF THE MOON. 23

geocentric zenith distance ; z1 the apparent zenith distance ; and d the
geocentric N.P.D.

59. The arrangement of the observations in Table X., and the values of
the longitude derived from them, require but little explanation. The
observed R.A. of the Moon's bright limb has been corrected for diurnal
aberration, and the Tabular R.A. has been interpolated with fourth differences
from the section Moon-culminating Stars in the Nautical Almanac, on the two
assumptions that the longitude was 10h. 31m. 0s. and 10h. 32m. O. west of
Greenwich. The adopted correction to the Tabular R.A. is taken from
the Appendix, and depends upon all the observations made at Greenwich,
Washington, Paris, Konigsberg, Strasburg, Oxford, and the Cape of Good
Hope. These corrections are generally reliable to the extent of 09<05, but
occasionally, as at the end of the 1874 October lunation, and at the end of
the 1875 January lunation, they are doubtful to the extent of 0s* 1 or even
more.

60. The clock-correction, proper to apply to the transit of the Moon to
obtain the apparent Right Ascension of the limb, has been given with the
observed transit, Table IV. When a sensible difference occurs between the
clock- correction obtained from stars near the Moon in declination and that
obtained from the other stars of the same group, the former has been
adopted, if the Right Ascensions are sufficiently well determined.

61. The weights assigned are proportional to the square of the change
of Right Ascension in 1s. Half weight has been given to the observations
on October 20, October 24, October 27, January 17, for reasons contained in
the Notes.

62. The longitude of the transit pier is obtained as follows : —

Observer. J> I. Number of Obs. ? II. Number of Obs. Mean.

3

s

h m s

Noble

24-9

7

23-3

5

10. 3i. 24-1

Ramsden

28-0

10

26-5

6

10. 3i. 27-2

Tupman

25-7

. 8

27-7

16

10. 3i. 267

Mean 10. 3i. 26-0

These results are, however, not entirely free from systematic error, proceeding
from the circumstance that the observations at Honolulu were made by
eye-and-ear, whereas the observations at the fixed observatories, from which
the errors of the tables are deduced, were made generally by the chrono-
graphic method.

24 TRANSIT OP VENUS, 1874. HONOLULU.

(2.) Longitude of Honolulu Station from tlie observed Zenith Distances of the
Moons Upper and Lower Limbs. Tables IX. and XL

63. Honolulu is very favourably situated for determining the longitude in
this manner in the winter months, as the observations can be secured when
the Moon's orbital motion is more or less perpendicular to the horizon,
a condition, it is hardly necessary to remark, which was always observed.
The observations were taken by Mr. Nichol and myself, fundamental
time being taken from the transit-clock. Six or eight vertical transits of
the Moon's limb, and two of a well-known star pretty near the Moon, con-
stituted a complete observation ; the instrument being, of course, used in
reversed positions. The observations of the Moon are, on the average,
rendered differential by means of those of the stars, and thus any error that
might creep in from the error of the transit-clock having been determined
by different persons is eliminated from the mean.

64. The observations of the stars were first reduced in the following
manner : — The observed clock-time of vertical transit of the mean wire was
reduced to local sidereal time by the application of the clock corrections in
Table VI. This was the sidereal time at the transit pier and not at the
altazimuth pier, as it should have been. With this slightly incorrect sidereal
time, and adopted co-latitude 68°. 42'. 3"'l, was computed the star's tabular
zenith distance given in the seventeenth column of Table IX., using the
fundamental place of the star in Table VII.

The correction due to the difference of time (Os>074) between the transit
and altazimuth piers was then applied, and the true tabular zenith distance
obtained. This was compared with the observed zenith distance with the
following results, for the excess of the tabular quantity when the star is east,
the reverse when the star is west : —

EXCESS of the TABULAR ZENITH DISTANCES of STARS over the observed ZENITH
DISTANCES, with changed sign for STARS WEST of the MERIDIAN.

Observer, Nichol. Observer, Tupman.

// //

1874, Oct. 5, a Leonis -f 4-3 1874, Oct. 3, 7 Leonis + 4-0

19, Fomalhaut + 3'3 7, a Leonis — r3

24, Procyon .......— o'3 i5, <r Sagittal ii — 3-o

27, a Aurigae + ro 23, ,3 Andromedse. . . — 1-2

28, Procyon + 2'8 25, « Tauri — 0-8

LONGITUDE FROM ZENITH DISTANCES OF THE MOON.

25

Observer, Nichol. tl

1874, Oct. 29, Procyon — o-3

Nov. 1 5, 8 Capricorn! .... — 3'i

1 6, Fomalhaut + 1*4

22, a, Arietis + o-3

23, a Tauri

27, y Leonis .

28, ft Ursae . .

29, a Leonis .
29, a Leonis .

Dec. 14, ft Ceti . . .
i5, ft Ceti . . .
1 8, a Arietis.

o'o

— 0-8

— i -o

— 3-o

— 2'2

+07
+07
- 0-6

Observer, Tupman,

1874, Oct. 26, a Tauri

26, a Tauri

26, Procyon

1875, Jan. 20, ft Gemiuorum.

20, (3 Geminorum

20, ft Geminorum.

2 1 , a. Leonis
21,0. Leonis

22, ft Leonis

22, ft Leonis ....

+ 2-0

O'O

4- 0-4
+ o-5
+ o-3
ro
o-3
— o-i

- 2-3

- 3-3

+
4

19, a Tauri ........ + o'4

21, y Geminorum
26, 8 Leonis
3o, a Yirginis

— r3

— i -8

— o-5

3i, a2 Libras ...... + r

1876, Jan. i, a2 Librae

1 3, ft Arietis ,

14, ft Arietis

1 6, a Tauri ....... 4- i -3

1 8, y Geminorum .
19, ft Geminorum .
19, ft Geminorum. .
19, ft Geminorum. .

23, 8 Leonis

24, ft Leonis

25, a Virginia

27, a. Virginia ...... + 3'2

27, a Virginia ..... — 2-o

The means of the above numbers

— 2*9
+ 3'i
4- 1-4

— n

— ro

— 2'5

— o-3

are, for Mr. Nichol — o% i o
for Capt. Tupman — o'23

These quantities show that a very small systematic error is introduced
by using the time found by the transit instrument.

65. The whole of the vertical transits of the Moon and of stars are given
in Table IX.

Column 4 is the mean of the clock times of transit over the five horizontal
wires. No imperfect transits were observed. No correction is ever required
for inequality of motion in z. d. The local sidereal time of observation
(subject to a small constant correction of + Os-07) is obtained by applying
to the time in column 4 the proper clock correction taken from Table VI.

Column 6 contains the reading of the vertical circle, as obtained always
from the mean of the four microscope-micrometers corrected for runs.

Column 7 is the level indication, always additive, and is the sum of the four
level readings divided by 2, the divisions on the levels being of the value of 2".

Column 8 contains the readings of the mercurial barometer suspended in

26 TRANSIT OP VENUS, 1874. HONOLULU.

shade in the open air, close to the altazimuth hut. The temperature of the
column of mercury was therefore sensibly the same as that of the external
air as indicated by the verified thermometer suspended on the north side of the
altazimuth observatory, the readings of which are inserted in the same column.

Column 9 contains the refraction computed as described on page 21. It is
additive to the circle-reading when the lamp is " left."

Column 10 contains the true observed zenith distance obtained by applying
the zenith point given at the bottom of the page to the circle-reading
connected for level and refraction.

Column 11 contains the Greenwich Mean Solar Time corresponding to
the (slightly inaccurate) local sidereal time of observation on two
assumptions of the longitude, viz., 10h. 31m. O and 10h. 32m. 0s West of
Greenwich.

The Tabular Geocentric Right Ascension and North Polar Distance of the
Moon's center, given in the twelfth and thirteenth columns, have been inter-
polated with second differences from the hourly ephemeris in the Nautical
Almanac, and have been corrected for errors of the tables by the quantities
given in the Appendix. The corrections applied are not absolutely identical
with those used for the Moon culminations, but the difference is unimportant,
as explained in the Appendix.

The Moons Equatorial Horizontal Parallax and Semidiameter have been
interpolated from the 12-hourly ephemeris.

The Tabular Zenith Distance in the seventeenth column has been computed
by the normal-centric method, from the formulae given at length in the
introduction to recent volumes of the Greenwich Observations (Section Altazi-
muth Observations). The hour angle is shown in the sixteenth column.

The eighteenth, column contains the longitude as inferred from a comparison
of the two tabular zenith distances of the limb of the Moon with the observed
zenith distance in column 10. This longitude is subject to future correction,
in consequence of the original error in the local sidereal time as explained
above. The difference between the two tabular zenith distances corresponding
to the local sidereal time of observation affords the measure of the value of
the observation.

66. Table XI. contains the Altazimuth results for each day. Each result
is corrected, and all are combined with the assigned weights to form the
mean.

The correction in the fifth column is on account of the difference of
longitude between the transit and altazimuth piers, which was neglected in
forming the table of corrections of the altazimuth clock. It is thus
computed : —

LONGITUDE FROM OCCULTATIONS. 27

The vertical interval between the first and last wires is 734" '3; if t be
the interval in seconds of time required by the Moon's limb to pass over this
space during vertical transit, and zl ~ z2 be the difference between the two
tabular zenith distances corresponding to the two assumptions of longitude,
the correction to the longitude always positive in seconds of time is found

from the expression —

734-3 X os'Q74 X 60

t X (Zl ~ Z2)

The mean value of t and z: ~ z2 for the day has been used.

The weights in the seventh column are approximately proportional to the
square of the quantity zt — z.2. "When the zenith distance of the Moon at
the time of observation is near 80°, and also when the corrections to the
tabular place of the Moon have been unsatisfactorily determined, only half
weight has been allowed. The observations on three days have been rejected,
there being no data for correcting the tables.

The resulting longitudes of the Altazimuth pier are : —

J I. No. of Days Obs. j II. No. of Days Obs. Mean.

s

s

h m s

Nichol

25-7

22

29-8

24

10. 3i. 277

Tupman

20 '3

7

28-5

7

10. 3i. 26-9

Mean 10.31.27-3

(3.) Longitude of Honolulu from Occultations of Stars by the Moon.

For the reduction of the observed occultations, the corrections to the
Tabular Geocentric R.A. and N.P.D. of the Moon's center have been taken
as follows : —

Correction Correction

toK,A. toN.P.D.

1874, Oct. 14

— o-3o

— 2'2

,, i5

— o-3o

— 2'0

,, 19

— o'4i

+ 17

,, 2-3

— o'6i

+ 4'4

Nov. 1 3

— 0-37

+ 27

The Moon's R.A. and N.P.D. were interpolated with second differences
from the hourly ephemeris in the Nautical Almanac, on two assumptions of
longitude. The parallaxes were then computed from the formulae —

-r, T, • T> A a. sin A i a3 sin 2 A a3 sin 3 h

Parallax m R.A. = -g^-p'" "•" sin 2" ' sin 3," '

where

a = sin p . cos <fi . sec 8

/ sin p . sin </A sin h1

tan 81 = ( i '-^— r tan 8.

\ sm 8 / sin h

28

TRANSIT OF VENUS, 1874. HONOLULU.

In these formulae 8 and h are the geocentric declination and hour angle
respectively ; 81 and hl the apparent values ; p is the Moon's equatorial
horizontal parallax corrected for the latitude of the place ; 4> the geocentric
latitude.

For the Augmentation of the Moon's semidiameter the approximate apparent
altitude was computed, and the Augmentation taken from the table in LOOMIS'
Astronomy, 7th edition, page 378. A constant correction of — 2"'00 was
applied to the augmented semidiameter, all the occultations having been
disappearances at the Moon's dark limb.

COMPARISONS of the CHRONOMETERS used for OCCULTATIONS with the TRANSIT CLOCK.

Approximate
Local
Mean Time.

c

V

1

Time by the
Transit Clock.

Transit Clock
Slow on
Local Sidereal
Time.

Name
of
Chrono-
meter.

Corresponding
Time by
the Chronometer.

Chronometer
Slow on
L. M. T.

0

1874.

h m s

8

h m s

m s

d h

Oct. 14. 7

T

20. 1 5. io'o

+ 15-07

Q

6. 42. 1 1 '5

— i. 3'og

8

T

21. 47. I4'0

+ i5-i8

Q

8. 14. o'5

— i. 3-07

Oct. i5. 7

T

20. 3i. 43*0

+ 17-28

Q

6. 64. 46-5

— i. r5i

8

T

2i.3g. 8-0

+ 17-35

Q

8. 2. o-5

— i. 1-48

Oct. 19. 7

T

21. ig. 29*0

+ 2471

Q

7. 26. 46-0

— o. 58-o6

8

T

22. l5. 5'0

+ 2476

Q

8. 22. I2'0

— 0.58-12

Oct. 23. 7

J

20. 54. 4 1 -o

+ 32-og

L

6.48. i5-5

— 2.48-76

8

J

22. 27. 20'O

+ 32'20

L

8. 20. 3g-5

— 2.48-84

Nov. 12. 8

NI

0. 0. 2'0

+ 2-63

M

8. 3o. 1 5-5

+ o. 54'2g

13. 7

T

22. 29. 55'o

+ 3-i5

M

6. 56. 22-5

+ o. 5q-66

14. 8

NI

O. 4. 25"O

+ 3-52

M

8. 26. 35-o

+ i. 6-i3

OCCULTATIONS of FIXED STARS by the MOON, observed at HONOLULU.

[All are disappearances at the Moon's dark limb.]

.

B

fa-

Recorded

Correction

Local

1 874.

t

Telescope.

Star.

||

of Dis-

to

Mean

No.

I
o

6

appearance.

Chronometer.

Time.

h m B

m s

h m e

Oct. 14

T

6-inch Eq.

Wash. M.C.Z. 100, ig .

Q

6. 52. 7'3

— . 3'OQ

6. 5i. 4'2

i

T

Yarnall 6g62

Q

7. 4. o'5

y

— . 3'OQ

7. 2. 57'4

2

J

T

Yarnall 6g64

Q

7. 1 3. 5q'7

u
— . 3'OQ

/ / ~

7. 12. 56-6

3

Oct. 1 5

T

gra. I7h.3g'im,— 28°.4i'.

Q

/ y i

7. 33. 5ro

J

- • '-49

7.32.49-5

4

,

T

8m.i7h.39'6m,— 2 8°. 35'

Q

7.37. i3-8

— . 1'49

7. 36. 12-3

5

>

T

gm. I7h.39-2m, — 28°.4i'

Q

7. 38. 53-o

7.37. 5r5

6

T

0. Arg. S. 17202 . . . .

Q

7. 40. 56'Q

— . 1 '4.Q

7. 3a. 55'4.

7

»
> >

T

gm. I7h.39'gm,— 2 8°. 2 2'

Q

/ T .7

7.49.48-0

T:/
— . 1'48

/
7. 48. 46-5

/

8

9 >

T

,

lorn. I7h.40'im, — 28°.22'

Q

7.56. 87

— . I'48

7.55. 7-2

9

Oct. 19

T

3|-inch . .

38 Capricorni

Q

7. 46. 35"o

— o. 58'og

7. 45. 36'Q

10

Oct. 23

J

e Piscium

L

/ f" •

7. o. 43-5

— 2.4878

/ T y

6. 57. 54-7

1 1

Nov. 1 3

T

) J

B.A.C. 6628

M

/ T

6. 46. 2O'4

+o. 5g'66

1 ~ i

6. 47. 2O'I

NI

3-inch . . .

M

T T

6. 46. 2O'2

+o. 5g'66

6.47. ig-g

I12

Oct. 23. Observed by Mr. Johnson.

LONGITUDE FROM OCCULTATIONS.

29

CQ
S5
O

I— I

I

&
O

o

T5
I

SH
OJ

CO

rO

O
<D

i/J e*-(

C9 O

w n <u 0)

S t3 u ^3

•2fg.2<

'•3 a? S

•

•o

Si

a

3

3

Favorable.

•

Favorable.

«

Favorable.

Unfavorable.

Favorable.

1 1

1 1

H

i

« 05

a -

a 6

00

d

CTI
b

d

>n

00
CO

d

<0

d

CM

d

CO

CM
CO

d

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30 TRANSIT OF VENUS, 1874. HONOLULU.

Giving each day the weight 1, and rejecting only October 15, the mean
result from the occultations is 10h. 31m. 26"-9.

We have, therefore, the* following determinations of the longitude of
Honolulu station : —

h m s

By the Meridional Transits of the Moon 10. 3i. 26'o W.

By the Zenith Distances 10. 3i. 2y-3 „

By the Occultations of Stars 10. 3i. 26*9 „

67. In the year 1868, M. Fleuriais, at his station in Emma Street, observed
19 meridional transits of the Moon's first limb and 8 of the second limb.
His observations are published in detail in the additions to the Connaissance
des Temps for 1872. The result reduced to APUA Station is 10'1. 31m. 228'25,
a determination of great value, M. Fleuriais having had much experience of
this description of observation; and, which is equally important, the errors of
the lunar tables having been very satisfactorily determined at Washington,
Oxford, and Greenwich. It depends, however, upon a single observer.

In the next section will be found the account of an attempt to connect
Honolulu with San Francisco by chronometers, the result giving the longitude
of Honolulu 10h. 31m. 33S>2, which, however, has little value, as explained
hereafter.

Weights being given to the above lunar results according to the number
of observers, that is to say, the mean obtained in 1874-5 by transit and
altazimuth having the weight 4, and M. Fleuriais' the weight 1, and giving
the occultation result the weight 5, the resulting longitude is —

10h. 31m. 26s-3 ± 2s (say).

The longitude used for the computation of the tabular quantities required
in the final equations representing the observations of the Ingress of Venus
is 10h. 31m. 27s-3 West of Greenwich ; the Greenwich times, therefore, require
the correction, 3 t = — ls>0.

CHRONOMETRIC CONNECTIONS.

68. It was understood to be an essential part of the programme at Hawaii
that the relative longitudes of some of the more distant islands should be
determined; and this would have been done, although perhaps not so
thoroughly, had the observations of the Transit of Venus failed.

The stations that were chronometrically connected with the head station
at Honolulu (Apua) were the observatories of Professor Forbes at Kailua,
Hawaii (Owyhee) and of Mr. R. Johnson at Waimea, Kauai (Atooi), distant
150 and 110 nautical miles respectively from Honolulu.

CHRONOMETRIC CONNECTIONS. 31

The details of the determination of local time at the three stations will be
found in their respective sections.

69. The chronometers supplied to the Expedition from the Eoyal Observa-
tory, Greenwich, were —

A. Brockbank, 602. Box 2-day. Five beats in two seconds. Solar.

B. M. Tobias, 56 1. do. Beating half-seconds. Solar.

C. Dent, 2667. do. do. do.

D. Molyneux, 2189. do. do. do.

E. Weichart, 233g. do. do. do.

F. Cotterell, 3i i. do. do. do.

H. Webb, 538o. . do. do. Sidereal.

J. Fletcher, 2705. do. do. do.

K. Norris, 828. do. do. Solar.

L. Blackie, 538. do. do. do.

M. Cotterell, -££&. do. do. do.

O. M'Cabe, 160. Box i -day. Five beats in two seconds. Solar. Very small.

P. Molyneux, 5174. do. Half-seconds. Solar. Not compensated. Balance

brass. Small.

Q. Park, and Frod., iog5. Box 2-day. Half-seconds. Solar. Small.

R. Arnold, 555. Box i-day. Half-seconds. Solar.

S. Arnold, 6062. Pocket i-day. Five beats to two seconds. Solar.

In addition to the above there were used : —

G. Fletcher, io5o. Box 2-day. Half-seconds. Solar. Belonging to Captain Tupman.

N. Leplastrier. Box 8-day. Half-seconds. Sidereal. Lent by Mr. W. De la Rue.

U. Arnold & Dent, 756. Box 2-day. Half-seconds. Solar. ->

V. E. T. Massey, no. do. do. do. lThe

W. McGregor & Co., 3/g5. do. do. do. J

RH. Barraud, g82. do. do. do. -i

RM. Muirhead, 2169. do. do. do. >The

RB. Birchall, i. do. do. do. J

Mr. David Flitner, chronometer maker of Honolulu, most generously lent
the following six chronometers : —

AA. H. Frodsham, 2022. Box 2-day. Half-seconds. Solar.

BB. Bliss & Creighton, y35. do. do. do.

CC. Black & Murray, 527. do. do. do.

EE. Roskell, 511-41446. do. do. do.

FF. Negus, 1 1 23. do. do. do.

GG. Dent, 2397. do. do. do.

Captain Daniel Smith, Harbour Master at Honolulu, also kindly lent the
chronometer —

DD. G. E. Frodsham, 655 1. Box 2-day. Half-seconds. Solar.

32 TRANSIT OF VENUS, 1874. HONOLULU.

It may be stated here that the chronometers J, L, and N formed part of
Mr. Johnson's equipment at Waimea after 1874, November 6.

Chronometers 0 and Q were with Professor Forbes at Kailua.

P was overwound during the first run.

R was kept in use at Honolulu for comparing clocks.

The chronometers U. V, and W were generally employed as the portable
watches to be carried ashore for comparison of chronometers.

70. The 18 chronometers first on the above list were lodged 1874,
October 2, under the stage whence the model (see plan) was observed.
They were compared with the transit clock every Sunday at noon, which
served to indicate those which had the steadiest rates. 0 and S were very
unsteady, while H, G-, B, C, D, and M seemed to be the most reliable. The
temperature was very uniform, at about 70°.

On 1874, November 2, 0 and Q were sent to Kailua. On November 6,
J, L, and N, were sent to "Waimea.

71. Captain Cator, of H.M.S. Scout having decided to send H.M.S.
Tenedos to Kailua for a short time, for the purpose of rendering assistance
to Professor Forbes during the Transit of Venus, advantage was taken of
this opportunity for comparing the transit clocks at Honolulu and Kailua.

On December 5, at 4 p.m., the chronometers B, F, K, and M were placed
on board the Tetiedos, and well bedded in tow. U, V, and W occupied
their own places in the ship's chronometer box. The same evening the seven
were compared with the transit clock at Apua by Mr. Nichol and myself
using M, V, and W, to be carried ashore.

72. Here it will be convenient to describe once for all how the chrono-
meters that never left the vessel were habitually compared with the transit
clocks on shore. At Honolulu the landing-place for ships in harbour was
1,300 yards distant from the observatory at Apua. The portable chronometers
were slowly carried by hand this distance, never placed in a vehicle. The three
solar chronometers used as portable watches (generally U, V, and W,) were
compared with the others, which may be called ship chronometers, then taken
on shore in a small boat, carried to the transit clock and compared with it
by coincidence of beats, taken back to the ship without loss of time, and
again compared with the ship chronometers. Everyone of these operations
was performed personally by Mr. Nichol or by myself. The comparison
of the portable watches with the others was effected by the same two
observers, one of whom gave signals with the beats of the ship chrono-

CHRONOMETRIC CONNECTIONS. 33

meters, while the other estimated the time to the nearest tenth of a second
by the portable watches. They then changed places and the first observer gave
signals from the portable watches. This method eliminated the errors of
comparing, and was less fatiguing than taking a sidereal chronometer all
round for coincidence of beats.

73. The Tenedos sailed the same night, December 5, for Kailua, Lieutenant
Lloyd kindly undertaking the winding. She arrived at Kailua on the
morning of December 7, when Professor Forbes, assisted by Lieutenant Lloyd,
without loss of time compared the chronometers with his Transit Clock by
means of Q, V, and W.

The Tenedos sailed from Kailua on December 9 at 2 p.m. Immediately
before her departure Professor Forbes made another complete comparison
with his clock, using the same three portable watches. She arrived at
Honolulu on the morning of December 10, when Mr. Nichol and I made
the comparison with the Transit Clock, using R, V, and "W for the purpose.
This completed the first run to Kailua. Good observations for local time
were obtained at both stations in connection with the comparisons.

74. After the Transit of Venus, the work of connecting the stations was
commenced. It was arranged by Captain Cator that the Tenedos should make
all the runs. Captain Van der Meulen, her commander, entered into it with
spirit, and to his valuable assistance the success of these somewhat long and
tedious operations was due. A proper berth was fitted up on the lower deck
of the Tenedos, on the lockers round the mainmast. The chronometers, in their
own gymbal-boxes with the lids removed, were placed, two and two, in well
padded boxes, which were placed in the prepared berth, surrounded by about
8 inches of horse-hair padding to check the vibrations of the screw propeller.
On December 13, 20 chronometers were thus placed ; the three belonging to
the Tenedos remained in their own berths in the captain's cabin.

75. The Tenedos made the following journeys with the chronometers : —

h

1874, December 14. 3. Left Honolulu.

22. Arrived at Kailua.

17. i. Left Kailua.

2 1 . Arrived at Honolulu.

19. o. Left Honolulu.

20. i. Arrived at Waimea.
6. Left Waimea.

21. o. Arrived at Honolulu.

22. 2. Left Honolulu.

34 TRANSIT OP VENUS, 1874. HONOLULU.

h

1874, December 22.23. Arrived at Wai mea.

23. 6. Left Waimea.

24. o. Arrived at Honolulu.

1875, January 2. 3. Left Honolulu.

22. Arrived at Kailua.

4. 8. Left Kailua.

5. 12. Arrived at Honolulu.
9. 6. Left Honolulu.

22. Arrived at Waimea.

10. 8. Left Waimea.

11. 22. Arrived at Honolulu.

76. From December 14 to December 21, I went in charge of the
chronometers ; from December 22 to January 12, Mr. Nichol was in
charge of them. They were wound every day at noon.

Immediately on arrival at a station, and immediately before departing, the
chronometers were compared with the Transit Clock, three chronometers
being used for this purpose, as before described, the comparisons being made
by the responsible observers with as little delay as possible.

At Kailua the portable chronometers had to be carried about a quarter
of a mile from the landing place to the Transit Observatory ; at Waimea
about half a mile.

77. In reducing the comparisons, the error of each portable watch on local
mean solar time at the instant of its comparison with the Transit Clock was
first found, assuming for this purpose the following longitudes of the
observatories :—

h m s

Honolulu 10. 3i. 25 W.

Kailua 10. 24. o W.

Waimea 10. 38. 40 W.

As each ship chronometer was compared with each portable chronometer
before and after the latter was compared with the Transit Clock, the error of
each traveller on local mean time was directly obtained corresponding to the
instant of the latter comparisons. The separate errors derived from each of
the three portable watches never differ many hundredths of a second.

78. The whole of the comparisons of the portable chronometers with the
standard timekeepers at the three stations are exhibited in Table XII. Of
the determination of the errors of the ship chronometers, it is thought
sufficient to give the specimens in Table XIII., while their errors on each
day are given in Table XIV. The stationary and travelling rates are shown

CHRONOMETRIC CONNECTIONS. 35

in Table XV., as well as the differences of longitude inferred by each
chronometer.

79. From Table XV. we have the following results for the difference of
longitude between Honolulu (Apua) and Kailua observatories : —

m s

By the first run, 1874, Dec. 5 to Dec. 10 (7 chronometers) 7. 24-38

By the second run, 1874, Dec- H to Dec. 18 (22 chronometers) . . 7. 24-65
By the third run, 1875, Jan. 2 to Jan. 6 (22 chronometers) 7. 24- 89

Mean, Kailua transit east of Honolulu (Apua) 7. 24*64

And for the difference of longitude between Honolulu and "Waimea we
have : —

m 8

By the first run, 1874, Dec. 19 to Dec. 21 (22 chronometers) 7. i3'6g

By the second run, 1874, Dec. 22 to Dec. 24 (22 chronometers) . . 7. i3'3i
By the third run, 1876, Jan. 9 to Jan. 12 (22 chronometers) 7. 13-44

Mean, Waimea Observatory west of Honolulu (Apua) 7. 13-48

80. In the year 1872 Professor Forbes and I made some com-
parisons to discover our relative personal equation, by observing many
stars about the same time in the same instrument, with the following
results : —

8

May 21, clock slow, T — F = +0-04 weight 2"

May 22, „ „ = + o-i3 „ 2

ivr VMean +os-o5.

May 27, „ „ = +0-08 „ 2 f

' June 10, „ „ = — o-i3 „

At Kailua, on December 15, 1874, a rather unsatisfactory comparison was
made which gave T — F = +08<04. These results tend to show that there
is no great difference between Professor Forbes and myself ; consequently no
correction for personal equation has been applied to the difference of longi-
tude between Honolulu and Kailua.

No data exist for comparing Mr. Johnson's mode of observing with mine ;
the difference of longitude, therefore, between "Waimea and Honolulu is
affected by this relative personal equation to an unknown extent. Mr. Johnson
used a half-seconds chronometer when observing transits ; at Honolulu, of
course, the clock was employed.

F

36 TRANSIT OF VENUS, 1874. HONOLULU.

ATTEMPT TO CONNECT HONOLULU WITH SAN FKANCISCO.

81. H.M.S. Reindeer, Commander C. V. ANSON, R.N., was to convey the last
of the party from Honolulu to San Francisco, and as it was probable that,
at that season of the year, she would carry westerly winds all the way and
make a short passage, it was resolved to employ the chronometers to measure
the meridian distance. Her departure from Honolulu was fixed for March 20.

82. The errors of the chronometers were determined by observations of the
Sun, with a reflecting circle by Troughton and Simms divided to 20" and
read by three verniers, the Sun's rays being reflected from mercury under a
cover of glass in the usual manner to obtain the double altitude.

Mr. Noble called the seconds from the sidereal chronometer N, which was
chosen on account of its loud beat, distinctly audible to the observer with
the circle. Five double altitudes of one limb were taken, the circle and the
cover of the mercury trough were then reversed, and five double altitudes of
the other limb taken, all three verniers being read each time.* The chrono-
meter N was compared, by coincidence of beats, with the two solar
chronometers Q and R (which were not disturbed) before and after every
set of observations, and thus the observations gave the errors of these three
chronometers with equal accuracy. The errors of the others were obtained
by comparing them in the usual way with N, Q, and R, about noon each day.
The habits of observing and comparing were exactly similar at Honolulu and
at San Francisco, to avoid systematic errors. The Sun was observed 3h or 4h
from the meridian in the morning and in the afternoon. It will be sufficient
to give as an example the actual observations made on one day ; for instance,
those on 1875, March 9, Table XVI. The circle reading in the ffth column is
the mean of the three verniers. The index correction was found to be 22",
additive when the circle was read backwards. The N.P.D. of the Sun and
the equation of time have been interpolated from the Nautical Almanac for
the mean of the five recorded times, assuming the longitude to be 10h. 31m. 14s
west. The refraction has been computed, for the mean of each five observed
altitudes, from the Greenwich Tables. The semidiameter employed is the
mean of all the daily measurements.

83. Table XVII. is an abstract of all the errors obtained before leaving
Honolulu. Table XVIII. is a similar abstract of errors obtained at Mare
Island, San Francisco, where the Reindeer arrived on the morning of April 9.
Instead of making a short passage under favorable circumstances, she was

* The darkening glass fitted to the eyepiece of the telescope was always used.

CHRONOMETRIC CONNECTIONS. 37

unfortunately blown to the southward by a cold northerly gale, which caused
a fall of temperature in the chronometer boxes to the extent of 15° Fahrenheit,
and lengthened the voyage seven or eight days, the Reindeer being unable
to steam against the wind and sea.

Table XIX. shows the average rates of the chronometers before and after
the voyage, the mean of them, which are the adopted travelling rates, and the
difference of longitude between the stations as derived from each chronometer.

84. On the arrival of H.M.S. Reindeer at the U.S. Navy Yard, Mare Island,
the members of the Expedition were courteously received by Commodore
PHELPS, U.S.N., the Commandant of the Navy Yard, and all possible assistance
was rendered. The circle observations were taken on the summit of an
elevation in the Navy Yard, on which stood a small observatory, and near it
an inscribed stone on which the mercury trough was placed. This stone was
connected with the triangulation of the coast survey by Professor GEORGE
DAVIDSON who, by permission of the Superintendent, kindly supplies the
information regarding the longitude of the station.

85. The longitude of a station in "Washington Square, San Francisco, from
the Washington Observatory, D.C., was determined by elaborate telegraphic
signals in the year 1869 (U.S. Coast Survey Report, 1870). The inscribed
stone on the hill in the Navy Yard was connected with the triangulation of
San Francisco Harbour, and thus it was found to be in —

Latitude 38°. 5'. 53"' i North.

Longitude 8h. 9™. 5s' 08 West of Greenwich.

86. The mean difference of longitude between Honolulu and the Navy Yard
as given by the chronometers, rejecting only Q, S, and KH, on account of
their small size and previous erratic movements, is —

2h. 22m. 28S> 19 ± 38-o.,

whence the longitude of Honolulu appears to be —

ioh. 3im. 33"-2 ± 39-o., West from Greenwich,
a determination to which I can attribute but little value.

G. L. TUPMAN.

F 2

38 TRANSIT OF VENUS, 1874. HONOLULU.

OBSERVATION OF THE INGRESS OF VENUS, 1874, DEC. 8.

REPORT OF CAPTAIN G. L. TUPMAN, R.M.A.

The weather on the 8th of December 1874, was all that could be desired.
The sky was cloudless nearly all day, and of a deep blue, indicative of extreme
clearness. The N.E. trade wind blew lightly, not disturbing the unprotected
telescopes.

Great interest was taken in our proceedings by the native population of
Honolulu. Every tree in the neighbourhood of the inclosure, and every roof
commanding a partial view within, bore its living freight. Anticipating
some possible annoyance to us, Her Majesty, QUEEN KAPIOLANI, had taken the
precaution to make it known among the natives that " Silence " must be
maintained, and not a sound disturbed us all the afternoon. A great many
natives presented themselves at the gates, expecting to be permitted to view
the transit in the telescopes. Captain Cator, at my request, surrounded the
inclosure with a cordon of Marines, from H.M.S. Scout, chiefly with a view
of keeping silence.

HER MAJESTY the QUEEN and other members of the Royal Family most con-
siderately abstained from entering the inclosure on that day, although they
were frequent visitors at other times.

Major WODEHOUSE, Her Britannic Majesty's Commissioner, most kindly
tendered his assistance, and remained within the inclosure all the time. I
cannot refrain from here placing on record how much we were indebted to
his kindness and courtesy during our long stay in Honolulu.

The telescopes used at Honolulu were —

(1.) An equatorial of 6 inches clear aperture and 89 inches focal length, by
Messrs. T. COOKE AND SONS, of York, which had been purchased by the
Government from the executors of the late B. D. NAYLOR, Esq. ;

(2.) An equatorial of 4^ inches clear aperture and 69 inches focal length,
by the same makers, my own property ;

(3.) A telescope of 3f inches clear aperture and 57 inches focal length,
by DOLLOND, mounted on a wooden tripod stand, with vertical and horizontal
motions ;

Plate EL

S2

5

i

*;

Jo face page 39.

kiccRruLO Lirn 22.BiD»OR» STCcvtuT GARDEN.

TELESCOPES AT HONOLULU. 39

(4.) A telescope of 3 inches aperture and 45 (?) inches focal length, by
T. COOKE, on a tripod stand, my own property.

These four telescopes, in common with most of the telescopes employed on
the Transit of Venus Expeditions, were fitted by Messrs. Troughton and
Simms with special means for observing the Sun, which, although well known,
it is proper to describe here.

The cone of rays from the object glass is intercepted, before the primary
focus, by a glass prism, one face of which is adjusted to an inclination of 45°
to the optic axis of the telescope, so as to reflect a portion of the light
approximately at right angles to the optic axis. About 90 per cent, of the
light and heat passes through the prism and is dispersed. The eye-pieces
of whatever character are inserted immediately above the prism. The 6-inch
and the 4^-inch equatorials were both fitted with new double-image micro-
meters by Messrs. Troughton and Simms. Plate III. represents one of these
instruments in position. The light is further toned down by an achromatised
wedge of neutral tint glass, placed between the two lenses nearest the eye.
The equality of the intensity of the two images is adjusted by the screw
which has the power of slightly altering the position of the axis of the
micrometer with regard to the optic axis of the object glass. The adjust-
ment of the reflecting prism is perfect when the micrometer can be rotated
about its own axis without altering the relative intensity of the two images.
This adjustment is liable to derangement from the circumstances that the
prism must not be too closely confined in its cell, as it is liable to become
very much heated when in use. No difficulty was experienced with either
telescope at Honolulu in regulating the intensity of the two images. This
double-image micrometer is described at length in the Memoirs of the Royal
Astronomical Society, XV. 199, and in the Monthly Notices, VI. 229, and
X. 160. One half of the divided lens was fixed, the other was moved by the
micrometer screw. They were not, however, provided with position-circles.

Both the equatorials were mounted upon iron pillars, which stood upon
piers of brickwork built up from the coral rock. The driving clocks, which
performed well, were adjusted to the Sun's apparent motion. The 6-inch
instrument was sheltered by a wooden hut, the roof of which could be
removed in pieces. The 4i-inch instrument was protected, when not in use,
by a small hut of wood and canvas, which was removed entirely when the
instrument was in use.

The Secondary Clock Dent 2012, the pendulum rod of which was of
wood, was mounted in the 6-inch equatorial hut, and was compared, when

40 TRANSIT OF VENUS, 1874. HONOLULU.

required, with the Transit Clock in the same manner as the Altazimuth
Clock.

Several days before the Transit of Venus, Lieutenants OLDHAM, SHAKESPEAR,
and CLAPP, of H.M.S. Scout, kindly attended at the observatories to rehearse
the intended operations. Lieut. Oldham was to assist Mr. Nichol, Lieut.
Shakespear to assist Mr. Noble, while Lieut. Clapp was to aid me ; and all
this assistance was most effective, and enabled the work to be well and
quickly done when every minute was precious.

Every observer had an adjustable seat, so that he could be perfectly at
ease.

At noon Mr. Nichol and I made a complete comparison of all the clocks
and chronometers intended for use, and provided for the contingency of any
of them stopping at a critical time.

At lh I carefully adjusted the direct-vision spectroscope on the 4|-inch
equatorial. Although I attach very little value to the observation made
with the spectroscope, it was sufficiently interesting to be worth recording.
The spectroscope was made by Mr. Browning, and consisted of a direct-vision
prism, of five components, two flint and three crown cemented togetheiv
sufficiently large to transmit a pencil 1'2 inches by 07 inches, with collimator
and examining telescope each of 7 inches focal length. The slit was opened
and closed by a small micrometer-screw acting against a spring. I deter-
mined the value of a revolution of the screw by opening and closing the slit
through measured ranges under the microscope. During my observation the
slit was open 0-0016 of an inch. The power of the combination was about 55 or
60 diameters. In the focus of the eye-lens of the small examining telescope
I inserted an opaque screen with a narrow slit in it, the width of which was
about ^th of an inch, and the length rather more than the breadth of the
spectrum. The Fraunhofer line C occupied the middle of this aperture, its
apparent width or image of the opening of the slit being about one half of
its breadth, so that the entire spectrum was cut off from view except the
C line and a narrow strip on either side. The spectroscope was firmly
attached to the telescope by a brass tube supporting it at its center of
gravity. There was an opening in this tube giving access to the slit, which
was of course placed exactly in the primary focus of the object-glass.

At 2h. 30m local mean time I placed the slit tangentially on the Sun's limb
at the expected point of first contact. The hydrogen stratum or " chromo-
sphere " was well defined. There was no prominence near the point of
contact, but the outer limit of the chromosphere was irregular.

TUPMAN'S OBSERVATIONS OP INGRESS. 41

Mr. Clapp recorded the times from the solar chronometer C, which at
2h. 25m was 7m. 55S>17 fast on local mean time, and was gaining O'OO per
hour (see comparisons, page 62).

At 3h. 14m. 17s-5 by the chronometer I first detected the planet entering
on the chromosphere. At 3h. 14m. 38s the curvature was so decided I was
sure that it was caused by the advancing limb of the planet. At 3h. 14m. 47s
I found it difficult to see the red line between the Sun's limb and the planet.
At 3h. 14m. 56s I imagined the red line was severed and contact took place.
At 3h. 15m. 15s there was a long black division in the middle of the C line
which was bright on either side, while the Sun's limb was just visible among
the minute irregularities on the edge of the slit. I felt sure that the contact
was passed.*

I then removed the spectroscope and proceeded to the 6-inch equatorial,
with which Mr. Nichol had been observing the external contact. Putting in
the double-image micrometer and adjusting it as quickly as possible, I made
the following measures of the distance between the obtuse cusps, Mr. Clapp
counting aloud the seconds from the Equatorial Clock, and recording the
observations : —

Equatorial Measures of Obtuse Cusps.

Clock Times. Micrometer Reading.

h m s r

20. 23. 38 4'5g2

20. 24. 17 4'320

20. 24. 3g 4'235

20. 24. 5i 4-200

20. 20. 12 3'8g5

20. 25. 28 3-995

20.25.42 3'7i5

20. 25. 56 3-696

It should be remarked here that the integer revolutions of the micrometer-
screw were reckoned in one direction only. When the two images coincided
and formed but one image, the micrometer-reading was approximately
10r>000. During the above measures, which are all on one side of the zero,
the focussing was slightly imperfect, as I discovered afterwards. The power
of the micrometer eye-piece was 250.

I then removed the micrometer and put in the negative eye-piece, power
150, fitted with an achromatised neutral tint wedge. I looked very carefully
for any fringe surrounding the planet, and for partial illumination of its disc.

* The local mean time of External Contact, inferred from the measures of cusps, is 3h. 8m. 42" -7
which is im. 41" 9 later than the " spectroscopic " contact.

42 TRANSIT or VENUS, 1874. HONOLULU.

I called Mr. Clapp to look at it. The planet was then about one third on.
Neither of us saw her entire disk, but we only spent a moment or two
looking at it, for just then the driving clock, which was being driven with a
light weight, stopped, and two or three minutes perhaps passe*d before things
were right again. Having replaced the micrometer, when the planet was
rather more than half on, I made the following three sets of measures of her
diameter in the direction parallel to the Sun's limb, on either side of the zero,
having carefully adjusted the focus : —

MICROMETER READINGS for DIAMETER of VENUS parallel to SUN'S LIMB.

jst Set. 2nd Set. 3rd Set.

r r r

2-875 16-870 2-900

2-846 i6'g2o Much " boiling."

2-916 16-918 2-886

3-145 (bad) 17-004 2-860

2-810 16-922 2-820

16-955 2-836

The brasswork surrounding the reflecting prism had now become too much
heated to be touched by the hand. The micrometer-screw, however, was at
a considerable distance from the prism, and I do not suppose the value of one
revolution could be sensibly affected.

As seen in the field of view of the double-image micrometer there was no
trace of the illumination in the planet's atmosphere seen at this time by
so many observers using Huyghenian eye-pieces. Had I seen it I should
probably not have known how to measure the distance between the cusps.

When I judged that about five minutes remained before internal contact
I began to measure the cusps, Mr. Clapp counting aloud the seconds from
the clock.

MEASURES of CUSPS before INTERNAL CONTACT.

Micrometer Micrometer

Clock Time. Reading. Clock Time. Reading.

h m s r h m s r

20.41. o 4'336 20.44.11 6-002

20.41.30 4*690 20.44.23 6-270

20.41.52 4-890 20.44.36 6-436

20.42. 8 4-915 20.44.47 6-645

20.43.31 5-700 20.45. I 6-918
20.43.44 5-804 20.45.25 7-466

20. 43. 53 5-86o 20. 45. 43 7-755

20. 44. 1 5-g85

Transit of Venus 1814 Dec. 8, at Honolulu.
Diagrams Ukistrating the Internal Gmlacf at, Ingress.

Plate IV.

Rg.1.

Local Sidereal time, W.46.1&5 ( lupman, 6 indirdractor.)

(These Diagrams should, le viewed,
at the distance of four feet.)

Fig. 2.

K. m, s.

local Sidereal time W. 46. 32~5 ( lupman., 6 inch, refractor. )

DANCERFIELD IIIH 22 BfDFCRD ST COVSKT CAROEN

To face page 43.

TOPMAN'S OBSERVATIONS OF INGRESS. 43

After calling the reading 6r'918 (at 20h. 45m. 1s) I placed the two images
in coincidence to estimate the time remaining before internal contact. This
I had frequently practised on the model, and generally was not more than
10 seconds in error. I remarked aloud to Mr. Clapp that it wanted a minute,
and proceeded to take the two last cusp-measures. Up to this time the circum-
stances of the Ingress of Venus exactly resembled those seen in the model.

I drew out the micrometer at 20h. 45m. 43s without reading it, laid it on
the shelf and inserted the negative eye-piece, power 150, down to the pencil
mark on it for focus. This I had repeatedly practised on the model, and
always effected in 10 or 12 seconds. I was no longer than usual on this
occasion. Mr. Clapp watched me, timed me I believe, and noticed that if
anything I was quicker than usual. On looking in (at 20h. 45m. 55s therefore)
I saw the cusps separated such a distance that I thought it still wanted
30 seconds* of contact, but the image not being perfectly sharp I threw it
out of focus with the rack motion, and brought it carefully in again. As I
did so I perceived that the cusps were united by a narrow band or thread of
light of sensible width, but faint, and instantly called " contact," though
fearing I had missed it while focussing. This was at 20h. 46m. 2s. As the
appearance at that instant made a vivid impression on my mind, I afterwards
made a drawing of it (Plate IV., Fig. 1), and may here very properly describe
it. The bright parts of the cusps were then far apart; the band of light
connecting them merged into them so guadually it was impossible to say
where the points of the cusps were. They no longer possessed the sharpness
I had seen with the micrometer eye-piece some 20 seconds before. The band
of light was of uniform width (calling width the direction perpendicular to
the limbs) and of unifor.ni shading for a considerable part of its length
between where it merged into the cusps. It was sharply defined along the
edge of the planet, but faded off gradually on its other border, where I
expected to see the limb of the Sun. Everything hitherto having so closely
resembled the appearances in the model, I felt certain that I had missed the
contact while focussing, although I could not understand how it could have
occurred so much sooner than I had expected. The preceding remarks refer
to the instant 20h. 46m. 2s. by the clock.

Mr. Clapp went on steadily counting the seconds. I was surprised that
the band of light did not change much in appearance for some time ; it
seemed a long time in comparison with model experience. There was no

:zr

V

* In the note book " 30 seconds " is entered, but in the account which I wrote after the transit I
said " 20 seconds." Whether intentionally or not I cannot now tell. It is unimportant.

a

44 TRANSIT OF VENUS, 1874. HONOLULU.

black drop nor ligament. The planet was perfectly circular, and nothing
whatever disturbed the sharpness of its outline at the place of contact. The
band of light [after a certain interval] gradually and imperceptibly brightened,
and as Mr. Clapp said " twenty " it was sufficiently bright to induce me to
consider the contact as established [by which I meant quite passed]. The
clock time for this is 20h. 46™. 20S-0. At that instant the general appearance
was similar to the model a second or two after contact, as nearly as possible
as represented in Fig. 2, Plate IV., which was drawn an hour or two
afterwards.*

On concluding the micrometer-measures given below, that is, about half
an hour after internal contact, I wrote some notes in the observing-book,
including the following : —

" At the 20 seconds which I have recorded I am perfectly certain the
contact was passed, established completely — not ' contact ' properly speaking,
for that implies some definite instant which was never observed. At that
time, and for a second or two before, there was the sliadmu on the light at the
point of contact, a phenomenon always seen with the model, but nothing like
a ligament or black drop, although I looked carefully for such an appearance."

Much disheartened at the unsatisfactory nature of the observation of
contact I withdrew from the telescope to look through the record of times,
and at my request Mr. Clapp took my place and scrutinised the planet. I
asked him if he could see a fringe of any kind near the periphery of the
planet, of shadow surrounding it, or diffused light within. He said he saw
nothing but a plain black sharply- defined circle. I called Major "Wodehouse
in also (not being able to commence " limb " measures immediately), and
called his attention to the same points with the same result.

I then replaced the double-image micrometer, and made the following
series of measures of the distance between the near limbs of the Sun and
planet, and of the diameter of the planet, reversing the direction of measure-
ment at 20h. 55m. and at 21h. 2m. when the position of the movable half-lens,
with reference to the fixed half-lens, was changed, as indicated by a line
drawn between the measures. At each change the telescope was re-pointed,
to bring the point of contact exactly in the center of the very limited field of
view, and the direction of measurement re-adjusted. It is here that the want
of a position- circle is most felt.

* In the reproduction of this diagram for the Astronomer Royal's " Parliamentary Keport " the
lithographer has incorrectly introduced a dark shadow between the limbs. Fig. 2, Plate IV., is a
correct copy of the original sketch.

TUPMAN'S OBSERVATIONS OF INGKESS.

45

MEASURES of the DISTANCE between the near LIMBS of the SUN and PLANET

after INTERNAL CONTACT.

Clock Times.

Micrometer
Reading.

Clock Timec.

Micrometer
Reading.

'

Clock Times.

Micrometer
Reading.

h m 9
2O. 49. 46

20. 5o. i
20. oo. 20
20. 5o. 3 1

r
10-914
10-973

io'g58
•101

h m s
2O. 54. I I
2O. 54. 21

20. 54. 36
20. 54. 5o

i rg35
1 1 -goo
u-g35

12-072

h m s
20. 5g. I 2

20. 5g. 24
20. 5g. 32
20. 5g. 47

r

7'25o
7-i65

7'3 10

7-040

20. 5o. 53

20. 5l. l6

20. 5i.35

20. 5l. 52

20.02. 5

20. 52. 24
20. 52. 37

20. 02. 5o

•o35

'252

•258
•427
•420
•353
•5oo
•6*5

20. 55. 45

20. 56. 2

20. 56. i3
20. 56. 29
20. 56. 40
20. 56. 55
20.57.38
20. 57. 58

8-072
8-o3o

7'995
7-965
7-875
7-782
7-532
* 7-625

20. 5g. 57

21. 0. 8
21. 0. 30
21. 0.40
21. 0.54
21. I. 12
21. 1.28
21. 1.46

7*141

7-075
6-910
7'o33
6-800
6-810
6-795
6-710

20. 53. 10
20. 53. 29
20. 53. 47
20. 53. 5g

•65o
•800
•760
•855

20. 58. 14
20. 58. 29
20. 58. 44
20.58. 57

7'3go
7-472
7-382
7-3cg

21. 2. 29
21. 2.01
21. 3. 6
21. 3.21

1 3-760
13-642
1 3-8oo
1 3-802

•Bad.

MEASURES of the DIAMETER of VENUS.

Micrometer Readings when the Images were in tangential contact.

r r

i6-gi5 3-ioo

16-990 3-o55

16-944 2-990

16-977 2-910

i6'gi5 3-ooc

16-975 2-945

1 6'g i o 2 -goo eye fatigued

i6-g3o 2'g85

1 6-900 3'ooo

16-900 2-848 bad

2-840 bad

3-127

Between every two micrometer-measures the screw was rotated in opposite
directions alternately, to eliminate any possible error that might arise from
turning it always in the same direction. It is unfortunately not recorded in
what direction these last measures of diameter were taken. '"I may or may not

G 2

46

TRANSIT OF VENUS, 1874. HONOLULU.

have rotated the' micrometer to place the head in a more convenient position,
as I was at that time ignorant of the fact that this form of micrometer is
liable to a variation of its zero as it is rotated about its axis. The measures
of limbs, however, are practically independent of the zero, while for the
cusp-measures the zero was determined immediately before them with the
micrometer in its proper position.

The Sun was now approaching the western horizon. Lieut. Ramsden had
secured 60 photographs, Mr. Nichol a series of micrometric-measures similar
to my own, and Lieut. Noble the telescopic contact. The clocks and chrono-
meters were then compared. Every observer made his notes in full before
any conversation passed between us, and wrote his Report, as here given
with no material alteration, the same evening.

TABLE A. — COMPARISONS of the TRANSIT and EQUATOREAL CLOCKS by intervention
of the SOLAR CHRONOMETERS R AND C and inferred ERROR of the
EQUATOREAL CLOCK, 1874, December 8.

Time by
Transit Clock.

Time by Chrono-
meter at Com-
parison with
Transit Clock.

Time by Chrono-
meter at Com-
parison with
Equatoreal Clock.

Time by
Equatoreal Clock.

Equatoreal Clock
slow on Local
Mean Time.

Observer.

h m a

h m s

h m 8

h m g

8

1 7. 6. 38-oo

R 1 1. 56. 3i'5o

12. 8. 8'5o

17. 18. iS'oo

12-38

T

I/. 47. lO'OO

R o. 36. 57-00

o. 32. 57'5o

17. 43. 8-00

12-37

T

21. 57. 35-00

C 4. 64. 52-5o

4. 67. 3roo

22. O. 1 2'OO

I2'02

Ni

22. 16. 6-00

C 5. 1 3. 20-5o

5. o. 3g-5o

22. 3. 2I'OO

12-53

Ni

I now proceed to the discussion of these observations in order to put
them in the form of final equations immediately available for the determina-
tion of the solar parallax, which was the special object of the Expeditions ;
premising that every observation resolves itself into a measure in a direction
joining the apparent centers of the SUN and VENUS, as seen from the place
of observation, and that the formulas by which the local tabular distance of
centers and the various co-efficients have been computed, were taken from
the Astronomer Royal's paper in the Monthly Notices of tlie Royal Astronomical
Society, Vol. XXXV., 277, the geocentric places of the SUN and Venus being
taken from the ephemeris for every 10 seconds of Greenwich sidereal time
computed from LEVERRIER'S Tables by direction of the Astronomer Royal.

DISCUSSION OP THE DOUBLE-IMAGE MICROMETEK MEASURES. 47

Let s, S, be the semi-diameters of Venus and of the SUN respectively ex-

pressed in revolutions of the micrometer-screw.
r, R, the tabular semi-diameters in seconds of arc.
2m, the micrometer measure in revolutions of the screw.
A, the tabular distance of centers.
p, the value of one revolution of the screw.

xr, x", the distance between the limbs that are nearly in contact, in
revolutions and seconds of arc respectively.

Then when the center of Venus is without the SUN, and 2m is the measure
of the obtuse cusps :

a* = 8 + * - (S* - m2)* - (s2 - m2)*
s is determined by observation ; S = •—" with sufficient accuracy,

r r

D = - -T- -

" S S

II 'II Of ,f . XT r~.

x + o x =. xr . p = -- 1 — 8 r

5* ft yf <\
or f> x st — ST.

S

The true distance of centers is

A + SA=rE + 8E + r-f8r- (x" + S x")

whence the final equation' —

0 = R + r - (A + x") - I A + & B + (1 - f) I r

where £ A is the sum of the corrections to the tabular parallax, B.A., and
N.P.D. each multiplied by the proper factor for its effect on the distance of
centers.

For the measures of acute cusps (near internal contact) the equation is —

0 = E_r-(A- x") - 8 A + 8 R - (1 - j ) 8 r
and for measures of near limbs (after internal contact) —

0 = E-r-(A + x") - 8 A + 8 R - (1 + f ) 8 r

With the 6-inch instrument we have, from the first series of measures of
the diameter of Venus

s — 3r-5i7,

and from the second series

* = 3r'4go.

{8"°c
"•c

48 TRANSIT OF VENUS, 1874. HONOLULU.

The several determinations of the zero of the micrometer are —

9r<891 from the first series of double-diameters.

10r-163 from the limb measures between 20h. 53m. 59s. and 2011. 56m. 40s.
10r-100 from the limb measures between 21h. Om. 40s. and 21h. 3™. 21s.

9r>956 from the second series of double-diameters.

For the reduction of the measures of Cusps the zero has been taken as
9r-89l ; and the value of s, 3r-517.

For the limb measures the zero has been taken 10r-130; and s, 3S-490.

.ff=976"-8o r = 3i"-42.

8"'g32 + • 286 8 r for cusp measures.
. g"-oo2 + • 286 8 r for limb measures.

Assumed astronomical latitude 21°. 17'. 56"'3 N.

longitude west of Greenwich 10h. 31m. 27S'3.

Similarly for Mr. Nichol's observations with the 4^-inch equatorial, we
have, from the first series for diameter of Venus,

s = 2r'448
and zero 9r'9g6 for the direction parallel to the Sun's limb.

and for the second series

s = 2r'434
zero ior>ooo (direction not stated ; probably parallel to Sun's limb),

J i2"-835 + "410 S r for cusp measures.
an f> • - ^ I2"-gi3 4. -410 8 r for limb measures.

The equations of distance of centers of the SUN and Vvnm for every obser-
vation with both instruments are exhibited in the following Tables B and C,
(which also give the time of contact deduced from each micrometer measure
of cusps,) taking the tabular semi-diameters as above, and assuming the
mean solar parallax to be

'. •' ' S -; 8"-950 (1 + ,-~).

The relative weights assigned to the cusp measures are arbitrary. The
model practice proved that the measures taken in the last two minutes were
about twice as accurate, for the object in view, as those taken between five
and three minutes from contact.

EQUATIONS OF DISTANCE OF CENTERS.

49

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EQUATIONS OF DISTANCE OF CENTERS.

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54 TRANSIT OF VENUS, 1874. HONOLULU.

By obtaining independent values of a revolution of the screws of the
micrometers, the terms depending upon or in these equations may be
eliminated. With this view the distance of the Model from the stage was
measured three times with a 100-feet measuring tape, the face of the model
being placed exactly 800* feet from the front edge of the table on which the
telescopes were laid. These projected a little over the edge, so that the
distances of the object glasses from the Model may be taken at

798*4 feet for the 6-inch telescope.
799'6 » 4^-inch „

The diameter of the disk of brass representing Venus was measured many
times with three different scales by TROUGHTON and SIMMS, with the following
results :—

2-85g4 inches (by a scale of T^).
2-8570 „ ( „ -jifr).

2-8552 „ ( „ millimeters).

The mean 2-8572 inches.

The mean of a great many measures of the diameter of the model planet
as seen in the telescopes gave the apparent values —

6r-76o ± -020 for the 6-inch instrument.
4r'76o ± -oio ,, 4^-inch „

Consequently the values of one revolution of the screws, for the focus cor-
responding to the distance of the model, are —

g"-O99 ± -o3o for the 6-inch.
i2"-8g7 ± -027 for the 4^-inch.

The focal lengths of the object glasses being, respectively, 89 and 69 inches,
the values of one revolution of the screws for the solar focus are—

g''-i84 for the 6-inch.
i2"-g8g for the 4^-inch.f

"We have, therefore, the following values of the true semi-diameter of
Venus : —

With the 6-inch instrument 32"- 18.
„ 4^-inch „ 3i"'7i.

Hence the value of 8 r is —

+ o"'76 for the 6-inch.
+ o"-2g „ 4^-inch.

* Mr. Gay, with the 66-feet chain, afterwards made the distance 802 feet by a single measure.
I doubt the accuracy of this.

•f I afterwards found by transits of the double image of Polaris the values I2"'99 and i3"'O2.

FINAL EQUATIONS FOR HONOLULU.

55

Colonel Tennant, by similar observations at Roorkee, made this quantity —

+ o"'56 for a 6-inch instrument ;

and Captain Browne, at Mokattam —

+ o"-62, also for a 6-inch instrument.

The following final equations represent the whole of the observations made
at Honolulu, omitting the micrometer measures of the distance of Iwibs with
the 4^-inch telescope, and the external contact observed with the spectro-
scope : —

Equation of Distance of Centers.

Observer. 1

Nature of Observation.

8"72

= — "-2 25 1 n + -7024 8 R, A. —-6481 8 N.P.D.

T

8 measures of obtuse cusps.

— "-o3g2 8 t — 8 R — -55g2 8 r

7""99

= — "-2283 n +-658g 8 R.A. —7002 8 N.P.D.

T

1 5 measures of acute cusps.

— "-03538* — 8R + -8384 8 r

8"-. 7

= — "-2283 rc +-66o58R.A. —-6980 8 N.P.D.

NI

1 7 measures of acute cusps.

— "-o3538<— 8R + 7866 8 r

7"-8o

= — "-2284 « +-653z 8 R.A. —7061 8 N.P.D.

T

Telescopic contact " passed."

—"•0340 8 t — 8 R + i -oooo 8 r

7"-83

= — "-2284 n +-6532 i R.A. —7061 8 N.P.D.

NO

Telescopic contact.

—"•0340 8 t — 8 R + i -oooo 8 r

7'V

= — "-2283M +-6629 8 R.A. —7064 8 N.P.D.

FL

Telescopic contact "passed."

— "•0343 8 t — 8 R +1-0000 8 r

7"-88

= — "-2279 « +-6264 8 R.A. -7338 8 N.P.D.

T

48 measures of limbs.

— "-o322 J t — 8 R + 1-6742 8 r

It is not without interest to compare the times of internal contact, as
inferred from micrometric measurements, with the observed telescopic time.
Before treating of the measures of the actual transit, I will exhibit the results
obtained from the preliminary practice with the model. This apparatus is
figured in Plate V., and needs but little description. The shaded portions
were cut out of sheet brass ; the curved edges, representing portions of the
limb of the Sun and the periphery of the planet, were bevelled to diminish
parallax ; the planet, attached to a horizontal bar running on fixed wheels,
was drawn towards the clock-work on the right by the action of the large
weight, the motion being regulated by a pendulum.

The curvature of the Sun's edges was such as would be proper for a
distance of 400 feet, but at Honolulu the model was erected at the distance of
800 feet, the planet being double the diameter shown in the plate. Sunlight
was reflected into the telescopes, through the triangular opening, by means of
a mirror mounted on another tripod stand, worked by an assistant, who knew
perfectly well when it was properly adjusted by the brilliant light reflected

56 TRANSIT OF VENUS, 1874. HONOLULU.

back to him by the glasses of the telescopes. The intermittent character of
the motion of the artificial planet was not perceptible in the telescopes.
These, removed from their mountings, were laid on a table as near together
as convenient, some eight or nine feet from the ground. A roofing of rushes
protected them and the observers from the direct rays of the Sun. The land
between was flat and grassy:

The exact dimensions of the important parts of the model were as follows :

Length of each chord of the Sun's limb 4'99 inches.

Radius of curvature of ditto 24'47 > »

Length of the base of the triangular opening 8^46 , ,

Height of ditto 2-94 , ,

Diameter of the planet (mean) 2'857 , ,

Length of the chord on the planet joining the two points

that touch the limb of the Sun at the internal contacts ... I '455 , ,

When the planet was set back horizontally exactly one inch from the
position of perfect internal contact at ingress, the distance of the cusps was
2-250 inches.

The horizontal movement of the planet was one inch in 270S>3 mean solar
seconds.

A mean-time chronometer was always used for the model practice.

The distance of the model from the object-glasses of the telescopes may be

considered —

798^4 feet for the 6-inch instrument.
799-6 ,, 4^-inch ,,

The practice with the model, at Honolulu as at Greenwich, demonstrated
that there was no material difference between the different observers' appre-
ciation of the exact moment of contact, no matter what telescopes were
employed, provided the power was 100 or more. By suitable experiments it
was found that the internal contact observed with the telescope was within a
small fraction of a second of time of true mechanical contact.

As regards the instant of internal contact the appearances of the model
bore no resemblance to the phenomena of the actual transit of Venus. The
comparisons of the various observers at the model therefore possess no
interest.

It is different, however, with the micrometer measures ; the circumstances
of which, as far as the eye could judge, were a perfect imitation of the actual
ingress of Vemis.

The daily micrometer practice on the model was a serious rehearsal of
what was to be done during the actual transit; and, the records being

Plate V.

To face page 56.

D*WCfcRfl£LD L

0 STCOVENT GARDEN

OBSERVATIONS OF THE MODEL.

57

preserved, I have since reduced the measures of cusps, by means of the
data given above, to see how they agreed with the true contact. The time
of internal contact was deduced from a cusp measure in the following
manner : —

The measurements of the model in inches were converted into their
equivalents in revolutions of the micrometer, by taking the diameter of the
planet as on page 54.

The small quantity by which the limb of Venus was outside the limb of
the Sun, measured on the line of centers, was found from the equation given
on page 47, and a table was then formed giving the distance of cusps
corresponding to every ten seconds of time from true contact. The interval
of time between the measure and true contact (called for convenience the
reduction to contact), which rarely exceeded 250 seconds, was taken from the
table for every cusp measure separately.

In order to test the accuracy of the data employed, more especially the
assumed velocity of horizontal motion of the planet, the driving apparatus
being of somewhat rude construction, I have separated the results of the
larger and smaller cusp measures. The following table exhibits these results
in sufficient detail. The telescopic contact was generally noted by one or
two observers in addition to the observer who took the measures.

The table proves conclusively that the time of contact inferred from cusp
measures is 3s or 4s too late for my own observations, and 4s or 5s too late for
Mr. NICHOL'S, the probable cause being that the extreme points of the cusps
are not seen, although they appear so sharp.

COMPARISON of the TIME of INTERNAL CONTACT at INGRESS, derived from CUSP
MEASURES of the MODEL with the OBSERVED TELESCOPIC CONTACTS.

(1.) Observer, TUPMAN.

By the larger Ousp Measures.

By the smaller Cusp Measures.

Telescopic Contact.

i>

On

o

Mean of JJ0. of
inferred «,
Times of Obser-

Meau
Reduction
to

Mean of flo. Of
inferred „.
Times ofi Obser-

Mean
Reduction
to

Mean of
observed

No. of
Obser-

Extreme
Discord-
ance from

Contact.

vations.

Contact.

Contact.

vations.

Contact.

Contacts.

vations.

Mean.

H

8

8

•

s

8

8

6-inch

46-0

5

162

42-2

4

63

3r5

2

0'2

» 5

5o-o

6

198

42-8

5

72

33-5

2-

O'5

5 5

og'o

2

208

57-o

2

• I 10

58-o

I

» >

i4-6

5

1 55

II'2

4

55

9-0

1

58

TRANSIT OF VENUS, 1874. HONOLULU.

Bj- the larger Cusp Measures.

By the smaller Cusp Measures.

Telescopic Contact.

I

Mean of
inferred
Times of

No. of
Obser-

Mean
Reduction
to

Mean of
inferred
Times of

No. of
Obser-

Mean
Reduction
to

Mean of
observed

No. of
Obser-

Extreme
Discord-
ance from

1

Contact.

vations.

Contact.

Contact.

vations.

Contact.

Contacts.

vations.

Mean.

H

a

a

3

a

a

s

6-inch

127

8

I92

8-5

6

72

3-o

2

o-5

»

57'o

6

181

53-5

6

74

49-2

2

o-3

5

24-0

IO

1 53

26-0

4

43

'97

2

O'2

9

35'4

5

121

3o-6

5

5o

3ro

2

o-5

>

35-o

5

92

3o-o

5

34

3ro

I

»

5-2

5

82

4-0

5

33

3-o

I

. .

44 -inch

4-0

5

IOI

4-0

4

46

i*a

2

o-3

i

41-2

4

1 06

44-2

3

7«

40' 2

3

0-8

i

3-o

4

&7

4-0

3

24

17

3

o-3

?

47

3

80

8-5

2

3o

5-5

i

>

27-8

5

79

28-6

5

37

25-2

2

o-3

Mean.

27-9

i3i

26-3

54

22-8

0-4

(2.) Observer, NICHOL.

i

•

S

9

•

•

6-inch

5-o

4

224

6-2

4

89

4-0

2

O'2

5

46-0

3

129

4i'o

3

65

33'5

2

o-5

>

3ro

3

io5

29-3

3

57

25-0

2

O'O

4^-inch

6o'o

4

'79

5g'5

4

93

53-2

2

o-3

54'o

5

143

59'8

5

81

52-2

2

0'2

5o-5

4

1 60

48-2

4

64

44-5

3

o'5

23-3

3

127

2I'I

3

66

19-8

3

o-3

117

4

7'

I2'O

3

3o

6-5

3

o-5

17-0

3

129

197

3

69

12-5

i

. .

I4'o

4

122

14*0

4

65

1 5-o

i

. .

53-2

4

96

49'°

3

39

45-o

i

. .

26-4

9

144

27-9

7

58

25-8

3

0-8

33-2

9

128

33-4

7

52

29-5

2

O'O

9*4

5

i57

7-6

5

68

o-5

2

O'O

Mean.

3ro

'37

3o-6

••

64

26-2

••

o-3

Coming now to the actual transit, the time of contact may be inferred from
each cusp-measure with great facility, since the local tabular distance of
centers has been computed for each recorded time.

The inferred times are given in Tables B and C affected by a quantity
depending on 8 r. Considering the internal contact only, we have the
following means of the times from the cusp measures :—

G. Sid. Time.
Tupman 7h. i8m. 4»'g -f 4-52 8 r where 8 r = + o"mj6.

Nichol 7h. i8m. io8'o + 5'g3Sr where S r = + o"'2g.

REPORT OF MR. J. W. NICHOL. 59

Hence the corrected inferred times are —

Tupman 7h. i8m. 8S< I G.S.T.

Nichol 7h. i 8m. 1 1 3 • 7

While the telescopic contact was certainly passed —

at 7h. i8m. o9. (Tupinan and Noble).

These results are in perfect accordance with those obtained by Colonel
TENNANT at Roorkee, who found the time of contact inferred from the cusp
measures to be 10s-2 later than the telescopic time of contact.

I may remark here, that although these cusp measures appear to be very
reliable, there is a very serious discrepancy between the observations at
Honolulu and at Roorkee, amounting to 17 or 18 seconds of time on any
reasonable assumption of the solar parallax.

I have thought it not worth while to make a similar comparison with the
measures of limbs, the co-efficient of 3r being very large.

REPORT OF MR. J. W. NICHOL.

The observation of external contact was taken by me with the Naylor
6-inch equatoreal telescope, with power of 145, and neutral tint glass.

Lieut. Oldham, R.N., took time for me, counting seconds aloud and making
the entries in the note-book.

The limb of the Sun was very rugged.

The first time recorded was when I perceived a definite indentation on the
upper limb of the Sun, and the contact must have occurred, from the size of
the indentation, 30 seconds to a minute before that time.

I then changed places with Captain Tupman, and going to his 4J-inch
equatoreal inserted the double-image micrometer eye-piece, the power of
which was about 150. The planet was then accurately focussed, brought
into the middle of the field, and the two images adjusted to equal intensity.
Twelve observations for diameter were taken, when the planet appeared to
be fully half way on the sun. The method of bisection was to place the two
images so that they separated and joined alternately as nearly as possible
to the same extent by the continued vibration of the air. By this time the
cusps were approaching, and the phenomenon appeared almost the same as
the model, except that the planet seemed somewhat brighter by contrast.

Seventeen observations of cusps were taken. The definition of the ex-
tremities of the cusps was as good as on an average day at the model, and I
found no difficulty in just getting them to touch.

"When the micrometer reading had diminished to 12M52, knowing from
previous model practice that I had more than a minute to spare before internal

i

60

TRANSIT OF VENUS, 1874. HONOLULU.

contact, I took out the double-image eye-piece, and immediately inserted a
negative eye-piece of power 130, furnished with a neutral tint sliding wedge.
The telescope was slightly disturbed in doing so, but that did not prevent
me from getting it re-adjusted and sharply focussed in 32 seconds after the
last reading of the micrometer, when to my astonishment I saw a completion
of light round the planet, perfectly distinct, and such as I should have said,
from previous model practice, was immediately after contact. This is the
time recorded. I remained looking at it for about two minutes, but could
see no instantaneous phenomenon of contact, no black drop, nor anything
resembling the model. I noticed that this light did not appear to thicken as
I should have expected for a considerable time after that recorded ; but as I
considered, from my previous experience (with the model), that the contact
had occurred, and was unable to get, accurately, any further change until
the planet was visibly on the Sun, I cannot say that the time as noted is at
all satisfactory.

The double-image micrometer was then replaced and 33 limb and 20
diameter observations taken. These were to my mind as good as any I could
have taken on an average day at the model.

The planet appeared circular, although the edge vibrated considerably.

20h. 19m. 23s. External contact first perceived. Time by Equatoreal
Clock [see page 46].

4^-inch equatoreal — double-image micrometer measures of the diameter of

Venus.*

Micrometer Readings.

5'ogi
5-088
5'o62
5-o8o

5-i55
5-J25

14-889
14-900
14-881
14-911
14-909
14-860

4^-inch equatoreal — double-image micrometer measures of cusps. Time
counted from chronometer C by Lieutenant Oldham, E.N.

Micrometer Readings.

Micrometer Readings.

h m B

r

h m s

r

3. 37. 49

14-101

3. 3g. 2

13-780

38. 2

I4-OI2

3g. 3i

i3-5n

38.38

13-853

3g. 5o

i3-435

* The reading of the micrometer for coincidence of the optic axes of the two halves of the
divided lens was approximately ior'o. Readings greater and less than i or • o indicate that (ho
movable half-lens was on alternate sides of the fixed half-lens.

REPORT OF MR. J. W. NICHOL.

61

h m s

3. 40. 5

40.27

40. 42

40. 5g

41. 18
41. 35

Micrometer Readings.
r '

13-35 1
13-282
1 3-ogo
13-024
12-782
12-719

h m s

3. 41. 48
42. oo

42. II
42. 21

42. 3i

Micrometer Readings.
r

12-074
I2-470
12-328
12-249
I2'l52

3h. 43m. 3s. Internal contact. Time by chronometer C. Double-image
micrometer measures of limbs.

3. 46. 56
46. 20
46.44

47- 9
47.21
47.41
48. 2
48. 7
48.38
48.55

49- i
5o. 5

5o.38
5o.56

52. 23

52.43

letcr Readings.

r

h m s

1 0-3 1 2

3.53. 7

10-443

53. 19

10-522

53. 3o

IO-552

53.53

10-562

54. 17

10-655

54.33

10-715

54.47

10-770

55.ii

10*840

55.26

10-880

55.36

10-910

55.56

i roi5

56.3i

11*140

57. 3

11-194

57.27

n-358

57.41

1 1-408

58. 8

Micrometer Headings.
r

11-482

I I -02 I

n-568
1 1-602
11-61 1
1 1 -780
11-792
11745
11-821
n-85i
n-823
12-042
i2-i35
12-148
12-276
12-290

Double-image micrometer measures of the diameter of Venus —

14-902
•85o
•845
•83 1
•880

•899
•859
•85 1

Micrometer Readings.

r

5-179
•143

•135
•078
•i3o
•i3o
•162
•090
•142
•143

14*928
•818

I 2

62

TRANSIT OF VENUS, 1874. HONOLULU.

Subsequent remarks, December 8, 8 p.m.

From what I learn from others who continued to observe during the whole
phenomenon with the same eye-piece, I feel inclined to think that the thin
line of light which I observed on changing the eye-pieces must have been
due to light from the Sun's corona. No light of the kind was visible in the
double-image micrometer, and I regret that it was changed, since otherwise,
1 think, a very good time of contact would have been obtained by it.

J. W. NICHOL.

Mr. Nichol's chronometer (see following comparisons) was 7m. 55S<17 fast
on local mean time.

COMPARISONS of the SOLAR CHRONOMETER C with the TRANSIT CLOCK, and inferred
ERROR of C on LOCAL MEAN TIME, on 1874, December 8.

Time by Transit
Clock.

Honolulu Mean
Time.

Corresponding Time
by Chronometer C.

Chronometer C Fast
on Local Mean Time.

Ob-
server.

h m s

h m s

h m s

m s

19.26. 23'OO
ig. 29. 24-00
21. 57. 35-OO

22. 16. 6-00

2. 16. 9-82
2. 19. 10-33

4. 46. 57-09
5. 5. 25-07

2. 24. 5-oo
2. 27. 5-5o
4. 54. 52'5o
5. i3. 2o-5o

7.55-I8
7.55-I7
7.55-4I

7. 55-43

Ni
Ni
T
T

EEPORT OF LIEUT. E. J. W. NOBLE, E.M.A.

The instrument I used was the Dollond telescope of 3^ inches aperture
and 57 inches focal length, with a solar diagonal prismatic eye-piece giving
rectangular reflection, a power of 139, and the darkest neutral tint glass.
The instrument, protected from the N.E. trade by a " bell " tent, was mounted
close to the door of the altazimuth hut, so that I could distinctly hear the
counting of the time-keeper, Lieut. Shakspear, R.N., of H.M.S. Scout, with
whom I had practised, and of the accuracy of whose counting I was quite
convinced.

As the time for external contact approached, I observed a slight notch on
the vertex of the Sun. At 20h. 17m. 11s. I was fully satisfied that Venus had
entered on the Sun, and I estimated that the external contact had taken place
2m. 30s. before [or at 'about 20h. 14m. 40s.].

I then left the telescope, and took only casual glances as the planet
advanced on the Sun till within about 10 minutes of the time of internal
contact, when I kept the instrument pointed on the Sun's limb.

REPORTS OF LIEUTENANT NOBLE AND ME. FLITNER. 63

Whilst thus watching I was astonished to see, most distinctly, the disc of
the planet complete, and immediately asked Lieut. Shakspear what time
remained before contact. He said " a little over five minutes."

There was an understanding between us about the Nautical Almanac time
being two minutes in error from the observed external contact.

The Sun's limb was very steady, and the planet was quite circular, with
a bluish rim round it.

The first time recorded at internal contact (20h. 45m. 43s. by the altazimuth
clock) is that when the cusps had apparently joined.

There was no black drop, no ligament, but a rough dark shade, which
gradually faded off to a thin tint, corresponding to the phenomenon I had
observed in the model. This — instead of being nearly instantaneous, as the
model generally showed — extended over some 20 seconds.

The thin tint is that recorded as the second time (20h. 46m. 2s.) at internal
contact.

At the third recorded time (20h. 46 . 22s.) there was a broad band of light
between Venus and the Sun's limb, and contact was long past.

The second- recorded time (20h. 46m. 2s.) by the clock is that which I consider
as the time of contact, and am certain it could not have been later than this.

E. J. W. NOBLE.

The altazimuth clock used for Lieut. Noble's observations (see Table VI.)
was 3O90 seconds slow on Honolulu sidereal time at the time of internal
contact. Assuming the longitude 10U. 31m. 27S>3 west, we have the following
equation corresponding to his recorded time, 20h. 46m. 2s.

Gr. Sid. Time.

7h. i8m.os-2, 7"-83 = — -2284 n + -6532 8 R.A. — 7061 8 N.P.D. —"-0340 8 t— *R+ Sr

MR. FLITNER'S OBSERVATION OF THE INGRESS OP Venus, 1874, DECEMBER 8, at

WAIAKIKI, NEAR HONOLULU.

Mr. Flitner kindly communicated to me, orally, the following circumstances,
which I committed to writing in his presence.

He observed the ingress of Venus, from the garden of Captain Smith's
house at Waiakiki, with an achromatic of 2|- or 2^ inches aperture on an
ordinary " pillar and claw " stand, furnished with a negative eye-piece of
power of 80 to 100 and a dark glass which screwed on at the eye-end for
viewing the sun directly. He used a pocket chronometer of large size and
showing seconds, which he compared with his standard clock at Honolulu on

64 TRANSIT OF VENUS, 1874. HONOLULU.

the morning of December 8, before going to "Waiakiki. Captain Smith had
taken with him the box chronometer, Frodsham 6551 (which he afterwards
lent to me for the longitude work). Mr. Flitner compared his pocket chro-
nometer with No. 6551 as below :—

h m s hms bras

No. 655 1 2.54. o-o No. 655i 3. 17. o-o No. 655 1 3.45. o-o

Pocket 2. 53. 22-4 Pocket 3. 16. 22-0 Pocket 3. 44. 22-4

The external contact was first perceived at 3h. 10m. 6s-5 by the pocket
chronometer. " Internal contact was complete and clear sunlight between
the limbs " at 3h. 35™. 50S-0.

I copied the above figures from the original records on small scraps of
paper which Mr. Flitner brought with him.

For the absolute error of No. 6551 on the afternoon of December 8 we
have the following connections :—

December 8, nb. a.m.

h m s

Flitnei-'s clock 10. 52. o'o "|

\ Observer, Fhtner.
No. 655i 10. 52. 32-5 J

December 9, near noon.

Flitner's clock 1 1 . 45. o-o "1

No. 655i 1 1. 45. 32-8 /

Transit clock at Apua . . 17. 23. 5ro ")

\ „ Nichol.
No. 655i o. 10. 3o-o /

Transit clock at Apua ... 19. 4. 4.0-0 "1

Chronometer (R) i. 5o. 22-5 J

Flitner's clock 2. 35. o-oo ~i

Chronometer (E) 2. 34. 52-85 / " "

Transit clock at Apua ... 21. o. i 'o "1

Chronometer (E) 3. 45. 25-o J

Mr. Flitner was in the habit of determining the error and rate of his
standard clock by observations of the Sun with a transit instrument, carrying
to his observatory, one-third of a mile distant, a half-second's chronometer.
He considered that his clock had a gaming rate of O09. The clock itself
was a fine specimen of Molyneux's work, with mercurial pendulum, and was
solidly mounted on the wall of Mr. Flitner's house, where it kept a fairly
steady rate all the year round, being regulated to mean solar time. From
the above comparisons, accepting Os-09 as the gaining rate of the clock, the
error of No. 6551 is deduced as follows : —

December 8, ioh. 52m. a.m., No. 655 1 fast 27s" 47 ') ,.

' } Hence the rate — o8' 14.
December 9, ii h. 40™. a.m., „ .,, 27s-56 J

MR. FLITNER'S OBSERVATION. 65

Mr. Flitner's pocket chronometer was therefore 10S>3 slow on APUA mean
time, and the APUA mean time of his observation of internal contact is
3h. 10m. 16s-8.

It only remains to state that Waiakiki is a village about 3 miles S.E. of
Honolulu. In computing the following final equation, which represents
Mr. Flitner's observation in the same terms as all the others, I have taken
hi s position as —

Latitude 21°. 16'. o" N. ; Longitude ioh. 3im. ig8-3 W.

whence the final equation,

7"- 91 = — c"-2283 n + -6629 B R.A. — 7064 B N.P.D. — o"-o343 8 t — 8 R + 8 r.

G. L. TUPMAN.

67

MERIDIONAL AND ALTAZIMUTH
OBSERVATIONS

AT

HONOLULU,

IN TABULAR ARRANGEMENT.

K

68

TRANSIT OF VENUS, 1874. HONOLULU.

TABLE I. — LEVEL EEROE of the TEANSIT INSTRUMENT at HONOLULU, determined by SPIRIT LEVEL.

[The sign + indicates that the East Pivot is low.]

Day.

Observer.

Sidereal
Time of
Level Deter-
mination.

Position of Head of 1
Micrometer Screw. 1

Level Error
corrected
for
inequality of
Pivots.

Day.

Observer.

Sidereal
Time of
Level Deter-
mination.

Position of Head of
Micrometer Screw.

Level Error
corrected
for
inequality of
Pivots.

1874.

h ra

//

1874.

h 111

//

October 2

T

21. 5

W

+ 5-62

October 8

T

22. 32 W

+ i'6i

T

22. 10 W

+ 6' 1 1

T

23. 36 W

+ 2-72

T

22. I4 W

+ 6-28

T

23. 40 W

+ J'97

T

22. 18 E

+ 5-86

R

o. 45 W

+ 2*46

T

22. 23 E

+ 6-i5

R

1.40 W

+ 3-47

T

23.22 E

+ 6'o8

NO

5. 35 W

-i- 1-16

NO

6. 20 W

+ 1-26

3

T

19.59 E

+ 5-37

C

T

20. 2 E

+ 5-14

9

SO

22. 35 W

+ 0-70

T

20. 16 W

+ 5-i7

NO

23.25 W

+ 1-67

T

21. 19 E

+ 5-56

T

I. 20 W

+ 2-33

NO

0.49 E

+ 5-89

T

2. 35 W

+ 3-02

NO

i. 38 W

+ 5-37

R

5. 35 W

+ 2'IO

NO

i. 55 W

+ r°9

R

6. 5o W

+ 3-57

4

H

o. 5o W

+ 4' 80

ii

NI

0.28 E

+ I'22

B

i. 3o E

+ 6-41

NI

o. 55 E

+ i'45

B

2.i5 E

+ 6-47

R

6. 5o , E

+ 2-11

R

7. 10 E

+ 2'2O

October 5, 3h. Altered Azimuth and Level Screws.

5

R

19. 36

E

+ 2-23

12

T

o.54 E

+ 0-86

R

20. 5

W

+ i-58

T

1.47 E

+ O'2I

K

21. IO

W

+ 2-36

NO

o. 20

W

+ 2-65

14

T

o. 53 E

+ 0-18

NO

0.53

E

+ 3-o8

R

6. o

E

+ ro6

NO

1.25

E

+ 1-71

i5

NO

23.25 W

- o-34

T

20. 6

W

+ 0-73

NO

i. 20

W

+ 0-64

T

20.45

W

+ l'O2

T

6. 36

W

+ i -02

T

20. 5o

E

+ i-75

T

21.36

E

+ 1-81

16

R

o. i5

E

+ 0-21

R

0.45

W

+ i-5i

R

2. 5

E

- 3'8o

K

i.3o

W

+ 2-56

17

T

19-43

E

- 3'54

K

2.35

W

+ 3-32

T

20.37

E

- 3-63

7

NI

20. 10

W

+ 0-99

NO

O. IO

E

- 3-o5

HI

20.43

W

+ 1-45

NO

1.25

E

- 3-i8

NI

21. 3

W

+ 1-51

n

5.45

E

- 3-i8

NI

21. 45

W

+ 2'2I

R

7-i5

E

- 1-87

It

22.35

W

+ i'&7

it

T

20. 34

E

- 3-3i

•

O. IO

W

+ 2-44

T

2. 15

E

- 2-66

TABLE I. — LEVEL ERROR OF THE TRANSIT INSTRUMENT (continued).

69

«*-

0 f

"o £

o>

Level Error

If

•* £

Level Error

Sidereal

§ CO

H t.

corrected

Sidereal

OJ 0

VfK

— -

corrected

Day.

tj

Time of
Level Deter-

V
*j

a o
o ~

for
inequality of

Day.

I

Time of
Level Deter-

~»f

§1

for
inequality of

!

mination.

• X U

•sji

Pivots.

mination.

••e.S
•»S

Pivot".

£>

o

o

c

P*

O

p-l

1874.

h „,

„

1874.

h m

„

October 19

NO

21. 40

E

- 2'30

November 3

NO

O. IO

W

- 0-46

T

I. 35

E

- 2-62

4

R

5. So

E

— 1'2O

20

R

21. 2O

E

- 2'3l

£

7.25

E

- 0-9I

U

22.35

E

- 2-5i

NO

1.25

E

— 2"O2

5

R

o.4S

E

— 1-98

R

2. So

E

- 2'lS

21

T

22. 2O

E

- 2'54

NO

7- °

E

- o-45

T

0. O

E

- 2-24

I

1.25

W

- 2-19

6

NO

o. 3o

E

— 1-04

NO

6. o

W

- 1-80

NO

I. O

E

— 0-8 1

R

6. o

E

- o-52

22

NO

23. 37

W

- 3-36

R

7.55

E

- 1-27

T

1.42

W

- 2-19

R

5.35

W

- 2'45

7

R

0.45

W

- i '47

R

6.55

W

R

2. 6

W

— I'O2

NO

7- °

W

- °'49

23

T

I. 0

W

- 2-19

T

1.28

W

- i-57

8

T

i. So

E

- 0-52

R

6.25

E

+ O'2O

24

NO

i.3o

W

— 2'o6

R

8.25

E

- 0-19

R

5. So

W

— 2'OO

9

R

o. So

E

- 0-68

25

NO

1.25

E

- 2'44

R

2. 30

E

- 0-97

R

3. 10

E

— 2^64

NO

6. 20

E

- 0-26

26

NO

3. 10

E

- i-33

10

NO

o. 3o

W

+ 0-32

NO

4. 1 5

E

- i-36

NO

1.55

W

+ 0-48

U

5. 3o

E

- i-36

R

7.20

E

- 1-14

ii

R

o.3S

W

- °'49

R

2. 2O

W

+ 0-19

27

R

o.55

E

- 0-84

It

2.40

E

- 1-27

12

T

1.29

W

O'O

NO

4.55

E

- 0-45

R

5. So

W

+ 0-4$

NO

6. i

E

- 0-71

R

8.45

W

+ 3-09

28

T

22.38

E

- i-59

i3

NO

o. 6

\v

- o-8S

T

22.58

W

- 1-70

NO

1.25

W

+ 0-87

29

tt

o.S5

E

- 1-89

T

7. 2

W

+ i-56

R

2. 40

E

- 1-40

T

7.59

W

+ 1-92

T

8. 4

W

+ 1-89

3o

T

1.25

E

- 0-84

T

2. 40

E

- i-33

14

NO

23.55

W

+ 0-16

NO

i. 5

W

+ i '46

November 2

T

23. 56

W

+ O'I2

.

R

5.55

W

+ I'OO

K 2

70

TRANSIT OF VENUS. 1874. HONOLULU.

"8 i

•8*

Sidereal

802

ffi ^

Level Brror
corrected

Sidereal

u

'S S

goa

hr< n

Level Error
corrected

Day.

bserver.

Time of
Level Deter-
mination.

osition of ]
Micromete:

for
inequality of
Pivots.

Day.

S
£

Time of
Level Deter-
mination.

jsition of 1
Micromete

for
inequality of
Pivots.

O

ft

0

PH

1874.

h m

n

1874.

h m

,/

November 1 5

NO

2O. 40

W

- o-36

December i

T

1.44

E

- 3-87

R

0.55

W

+ o'o6

T

3. i5

E

- 3-97

NO

7. 10

E

- 3-84

Some Cement, in a semi-fluid state, was poured under the Piers.

T

12. 2O

E

- 3-3z

16

T

6. o

E

- 1-92

T

22. 37

E

— 2'O2

2

R

5. 5o

E

- 3-58

R

0.55

E

- r66

T

12. 0

E

- 3-42

J7

NO

o. 5

E

- z-99

T

i. 3o

E

- 4-62

NO

6. 5

E

— 4-04

22

T

1.42

W

- 3-66

T

3.25

W

- a'97

4

NO

o. So

E

- 3-Si

NO

6.45

W

- 2-81

NO

1.55

E

- 4-14

R

5. So

E

- 3-55

23

NO

o.35

W

- 3-3o

NO

i. So

W

- 2-91

5

R

o. 45

E

- 3'94

23

T

4.25

W

- 2-61

NO

7. 10

E

— 3-09

T

12. IS

E

- 2-83

R

6. 10

W

- 2'45

6

T

22. 2O

W

- 4-08

24

T

i.39

W

- 3-46

T

1.43

W

- 3-46

25

R

o.55

W

- 3-92

7

NI

22. 30

W

— 4-44

R

i. 3o

W

— 3-40

R

0.45

W

- 3-72

T

13.27

W

- 3-82

NO

4.55

W

- 2-71

26

NO

o. 5

W

- 3-62

8

NO

o. 3o

W

— 4-04

NO

i. 40

W

- 2-91

NO

i.3o

W

- 3-i3

NO 7. 58

W

- 3-io

-

T

8. 7

W

- 2-84

27

NO

i.45

W

- 3'82

NI

1 5. 20

W

- 4-18

NO

i. So

W

- 3-3o

%

9

NO

o. 55

W

- 3-55

B

6. 3o

W

- 3-oy

R

5. 5o

W

- 3-62

T

9. 17

W

— 2'O6

T

10. 1 5

W

— 2-09

10

R

0.45

W

— 4'o5

NO

5. So

W

- 3-04

28

T

1.52

W

- 3-io

NO

7. So

W

— 3-40

ii

NO

1.42

5

- 3'6i

R

9. 20

W

- 2-71

R

4. So

E

- 3'94

R

10. 20

W

- ri8

12

H

o. 3o

E

- 3-o3

29

R

T

o.SS
10.55

W
E

- 3-79
- 3-91

i3

T

i.4S

E

- 4' 74

R

5. 10

E

- 4-66

3o

NO

I. 0

E

- 3.58

14

'
R

22.53

E

- 4.'43

R

6. 20

E

- 3-74

R

o. 55

E

TABLE I. — LEVEL ERROR OF THE TRANSIT INSTRUMENT (continued}.

71

"o •?

"8 *

-d S

Level Error

T3 **

Level Error

Sidereal

si u
Sa3

a h

corrected

Sidereal 1 &

K K

corrected

Day.

(H*

•

Time of
Level Deter-

?|

d g
o h

for
inequality of

Day.

1

Time of ^ |
Level Deter-

0 0

for
inequality of

1

mination.

.X O

•p

Pivots.

1

mination. "-3 -j:

§s

Pivots.

O

K

: O

PH

i

1874.

h in

/,

1874.

h in

//

December 1 5

NO

I. 20

E

- 3-39

December 3 1

R

0.25

E

— 2"O2

R

5. o

E

- 2-86

T

1 3. o

E

— I '04

T

i3.45

E

— no

16

R

23. 5o

E

- r3o

R

i.45

E

— 2-64

1875.

NO

6. 20

E

- 2-38

January i

NI

o. 39

E

- 2-41

NI

1 3. 24

E

- 2'l5

NO

6. o

E

- o-55

NO

7- o

E

- 0-68

J7

NO

I. 0

E

- 1-86

T

14. 20

E

- 0-87

R

6.15

E

- 1-92

T

14.48

E

- o-65

NI

1 3. o

E

- 2'3l

NI

i3. 25

E

- 2'54

2

R

0.52

E

- 1-82

R

5.55

E

- 0-68

18

B

I. O

E

- 2'3l

T

1 3. So

E

— o'i6

T

i3. 3i

W

- 2-48

3

R

i3. 5

E

— 0*09

J9

NO

2. 5

W

- 3-27

R

14. 1 5

E

+ 0-40

NO

6.25

W

- 0-79

4

R

o. 35

E

+ O'OO

20

NO

3.45

W

- 0-98

T

3.48

E

- 0-29

NO

6.25

W

- o-33

R

12. 2O

E

+ I'll

2J

T

5.20

W

- 0-88

5

R

5.52

E

+ O'2O

T

8. o

W

— O'OI

T

8. 10

W

— 0-04

6

R

o. 42

E

- l'I4

R

I. O

W

- 2'52

22

NO

6.45

W

— 0-43

T

6.35

W

- 0-46

T

i3. 3o

W

— 0-95

T

6.35

W

- o-52

T

7. 10

W

- 0-18

23

NO

7. 5o

E

- 0-74

R

12. 2O

W

— O'lO

«4

R

7- 5

E

— I '46

7

T

0.40

W

- 2'03

26

R

6.55

W

- 1-99

T

i3.23

W

+ 0-42

T

14. 3

W

+ 0-26

27

NO

5. 17

W

- 1-86

8

NI

0.55

W

— 2'O

December a8, 17^. Earthquake.

R

1.24

W

- i-5o

29

R

o. i5

E

- 1-82

R

3. 5o

W

- '"47

R

o. i5

E

- 2' I 8

T

13.23

W

— 0-04

NO

5.45

E ! - 2-08

9

T

7- I

W

- 0-66

T

13.40

E - i-36

R

i3. 5

W

+ o-55

3o

NI

o.57

E

- 2-47

R

13.55

W

+ o-35

R

5. 5o

E i - 2-18

10

T

o. 40

W

- 2-5o

NO

i3. i5

E - r75

K

6.25

W

- 0-82

72

TRANSIT OF VENUS, 1874. HONOLULU.

Ofe

"S*

Day.

1

Sidereal
Time of
Level Deter-

on of Head

rometer Sere

Level Error
corrected
for
inequality of

Day.

!

Sidereal
Time of
Level Deter-

on of Head
rometer Sere

Level Error
corrected
for
inequality of

1

mination.

tfl U

i§

Pivots.

i

r>

mination.

P

Pivots.

C

£

o

P«

1875.

h ill

,,

1875.

h ni

„

January 10

T

i3.z3

w

+ o-o3

January 20

T

i. 5

E

- 3-72

T

14. 20

w

+ 0-45

R

6. o

E

- 3-o3

R

8. 3o

E

- 3-i6

ii

T

i. i5

w

- ri5

T

i5. o

E

- 2'93

R

5.58

w

+ o-32

T

I 3. 20

w

- 0-18

21

NI

i.5o

E

- 3-35

T

7.40

W

- 3-i7

12

U

I. 20

w

- ri5

T

7.57

w

- 3-i7

•R

12.45

w

— 0-40

T

8.57

w

— 2' I 3

13

T

o. 42

w

- 2-32

22

R

i- 7

w

- 3-85

R

12. 5o

w

+ 0-16

T

8. o

w

- 3-oi

R

i5. o

w

+ i "07

R

9.40

w

- 2-78

'4

R

o. 5

w

- 2-16

R

ii. 3o

w

- 1-77

R

2. 50

w

— O'2O

23

NI

i. 5o

w

- 3'49

NI

14.36

w

- i-3i

U

6.25

w

— 2-39

i5

R

2.25

w

— 0-82

NO

10. 5o

w

- 1-86

•

U

3.36

w

— o-io

24

R

2.25

w

- 3-53

R

12.55

w

- 1-24

NO

6. i5

w

- 2-55

16

T

1.25

w

- 3-27

R

ii. i5

w

- 1-62

T

i. 3o

w

- 3-io

U

12. 55

w

- 0-17

R

3.25

w

- 2-65

25

T

2. O

w

- 3-io

R

6. 7

w

- i-34

T

12.25

w

- 2-o3

NI

i3. o

w

- 1-44

T

I 3. 20

w

- ''44

NI

i3. 3o

w

- i- So

NO

i5. i5

w

- 2-52

17

NI

o.57

w

- 2-5g

26

NI

2. 21

w

- 3-27

NI

i.35

w

- 2-84

NO

6. 5o

w

- i-83

R

4. 3o

w

- 1-47

T

i3. o

E

- 2'34

R

6. o

w

- i-53

T

14. 1 5

E

- 2-67

R

I 5. 20

E

- 1-92

18

NI

!• 7

E

- 2'5l

NI

1.24

E

- 2-83

27

NI

2.28

E

- 3-12

B

5. 3o

•E

- 1-71

It

5.55

E

- 2-70

R

6.45

E

— i-io

T

i3. 5

W

- 2-45

NI

1 5. 28

E

- r3o

T

14. 1 3

W

- r55

NO

15.55

W

- 2-35

19

T

i. 5

E

- 3-o9

28

NI

2.36

E

- 2-90

T

1.47

E

- 2-93

NO

6.33

E

- 2'l5

T

6.25

E

- 2-80

T

14.55

W

— 2'03

T

6. 5o

E

- 2-70

T

i5. i5

W

- ''73

TABLES I. AND II. — LEVEL ERROR AND COLLIMATION OF THE TRANSIT INSTRUMENT. 73

'S i

"o '-i

Level Error

rrt >-l

Level Error

Sidereal

too
MK

corrected

Sidereal

leg

corrected

Day.

Time of

S

•si

for

Day.

Time of

•

for

8
E

Level Deter-

0 a
||

inequality of

i

Level Deter-

a o

.2 o

inequality of

1

mination.

Pivots.

i

«

mination.

Pivots.

O

1S

.0

o

£

1875.

h til

„

i875.

h in

„

January 29

NI

2.23

w

— 3-40

February 3

XI

3. i

£

- 3-97

R

5.55

w

- 1-90

NO

7- 5

E

- 3-8i

T

14.55

w

- 1-24

6

T

2.48 W

- 3-33

I

1 5. 32

w

- 1-24

NO

7. 26

W

- 3-i(?)

3o

NI

2.35

E

- 2-38

NO

6.22

E

- 0-87

7

NI

3. 10

W

- 2-84

*T

15.32

E

- i-59

T

7-55

w

- 1-41

T

16. i5

E

- 1-25

R

12. O «

w

- o-9(?)

1

.

lS.40

w

— o'Sy

3i

T

2. 38

E

— 2'6o

HI

i5.55

w

- 0-69

]l

6. 5

E

— 1-46

8

T

3.17

w

- 4-64

R

15.22

E

- 0-94

R

8. 3o

w

- 3'5(?)

R

16. 55

E

- 2'3l

NI

12. O

w

— 2'O(?)

NO

15.40

w

- 0-88

February i

NI

2.24

E

- 3-58

11

6. 4

E

— 3-29

9

R

3.19

w

- 3-69

NI

9. 3o

w

- 1-44

2

NI

2.52

E

- 4-56

T

1 3. 5

w

- 1-24

NO

8. 5

E

- 3-52

T

i5.55

w

- 0-80

TABLE II. — COLLIMATION of the TRANSIT INSTRUMENT at HONOLULU, determined by OBSERVATIONS of

a CIRCCMPOLAR STAR, COLLIMATOR, or the MERIDIAN MARK, with REVERSED POSITIONS of the

TRANSIT Axis.

Heading
of Micro-

Heading
of Micro-

Day.

b

i dence of
observed. p

Day.

jj

Object
observed.

meter for
Coinci-
dence of
Center

c

H

Wire with

•1

Wire with

O

Optic Axis.

O

Optic Axis.

1874.

,

1874.

r

( )ptohor 2.

T

October 10

T

( 1ollimiitor

9f,

3

T

\ Ursa; Minoris .... 20 '232

i5

T

2O ' 3o2

NO

T

Collimator

It

Polaris 2O'2i8

T

Cephei 5 J

20 ' 3 i 6

5

It

\ Ursa; Minoris .... 20 '21 8

i

T

[At Noon, adjusted

6

T

\ Ursae Minoris .... 20-266

the Micrometer.]

T

T

Collimutor

20 ' oo 3

10

T

20^292

21

T

Polaris

2O'o3i

74

TRANSIT OF VENUS, 1874. HONOLULU.

Day.

Observer.

Object
observed.

Reading
of Micro-
meter for
Coinci-
dence of
Centre
Wire with
Optic A^iis.

Day.

|j

•

O

Object
observed.

Reading
of Micro-
meter for
Coinci-
dence of
Center
Wire with
Optic Axis.

1874.
October 28
November 4.
6

7

g
9

10

ii
i5

21

December i

2

T
T
T

»
NI

T
T
T
T
T
T
T
T
T
T
T
SI
T

T
T
T

Col
Mei

[A1

j'
c
a
tl

5"-

)»

1 8".

5".
1 8".

)»

Coll
Mei
Coll

Mer
Coll

Mer

20-043

20 '062
2O-O7Z

1874.
December 5

6

10

ii

H
18

21
23
26
27

i875.
January 3
6
10
i3
16
it

20
24
25
28

3i
February 6
8

T

NI
T
NI
T
R
T
NI
T
NI
NI

T
K
T
R
T
NI
T
R
T
NI
T
T
T

20- 108

20- 109

2O'IO2

20- 108
20 • io5
20* 094
20- in
20-109

20- 109

20 • 116
20- n3

20 • i 20
20-126
20- i 20
20- 114

2O-Il5

20-108
20- III

20- III
2O- III
20- III
2O- 114
20- IIO
20 ' I 1 1

4h. (Solar) ad-
isted the verti-
ility of the wires
ad tightened up
\e screws.]

Meridian Mark. .

»
»j « •

»

20-O68
20-069
2O '080
20-068
2O-O7O
20-072
20-064
20-067

20-o85
10-075
20-078
20-076
20-o83
20-080
20-079

20*096
20- 101

20*097

Mer. Mark (unsteady)
Meridian Mark

Meridian Mark

idian Mark

"

»

idian Mark

TABLE III. — AZIMUTH EKEOE of the TRANSIT INSTRUMENT at HONOLULU, and OBSEBVATIONS of the
MERIDIAN MARK.

[The Sign + indicates that the Optic Axis points East of South.]

Approx.
Local
Day- Mean
Time.

Observer.

Apparent
Stars or Meridian Mark. Error of
Azimuth.

Remarks.

1874- h -
October 2 12.27

3 7. o

12. 23

4 12. 19

T

T
NO

R

5-42

2-70
6-56

7'5o

A Ursac Minoris .... p Capri

Polaris e Piscium . . + i

TABLE III. — AZIMUTH ERROR OF THE TRANSIT INSTRUMENT (continued).

75

Day.

Approx.
Local

ML-UU
Time.

Observer.

Stars or Meridian Mark.

Apparent
Error of
Azimuth.

Remarks.

1874.
October S

3. o
6. 52

T
H

//
— omo6

Azimuth and Level adjusted.

6

12. 15

6. 49

NO

T

Polaris ... v Piscium
A Ursae Minoris .... 0 Capricorn!

+ 6-84

+ 2'32

12. 1 1

R

Polaris I1 Ceti

+ 5-n

7

6.45

NI

A Ursa; Minoris .... p Capricorn!

+ i'75

8

10. 17

T

Radcliffe 2705 S.P. . p Pegasi

12. 5

17. 3

R
NO

Polaris 67 Ceti
S Ursae Minoris S.P. « Orionis

+ 6'83

+ 7 '43

17. 32

NO

+ 5 * 02

9

12. O
16.59

T
R

Polaris v Piscium
S Ursae Minoris S.P. Cepbei 5i

+ 4*29

+ 7*43

u

II. 52

NI

Polaris /3 Ceti

+ 4." 6?

17. 20

R

+ 4-*QI

12

11.48

T

- 1-61

14

II. 40

T

+ 3-67

15

11.36
16.35

NO

T

Polaris e Piscium

+ 1-63
+ 4'85

17. 2

T

+ 4 '60

16

11.32

R

+ 3-75

!?

1 6. 27

R

S Ursae Minoris S.P. v Geminorum

— 6-19

1 6. 56

R

- 6-25

19

n. 20

T

- 7'35

Polaris boiling.

2O

n. 16

NO

- 5-75

Polaris boiling.

21

II. 12

T

- 4-80

1 6. 40

NO

- 5' 88

22

n. 8

T

- 3-83

Cloudy.

23

ii. 4

T

- 3-48

25

10.56

NO

— 0' 12

26

10. 52
I 6. 20

T
H

Polaris a Ceti

- 5'60

Polaris flaring.

27

10.48

R

- I-6?

76

TRANSIT OF VENUS, 1874. HONOLULU.

Day.

Approx.
Local
Mean
Time.

Observer.

Stars or Meridian Marl..

Apparent
Error of
Azimuth.

Remarks.

1874.
( )ctober 29

3o

10. 40
10 16

R

Polaris v Piscmm

//
+ o-o3

November 2

+ i • 60

3

Polaris 0 Ceti

5-62

4

4.. 0

T

{20 • 1 1 7 W. T
L

- 5-20

i5.43

R

20-008 E. J

— 3'7Q

5

10 i3

R

S'y

6

4.. O

T

r 20 • 042 E. -i
M.MJ L.

— 6-46

4. 5
4. 35

T
KI

L 20- 102 W. /

{2O'o57 E. T
k.

— V76

("Adjusted the verticality of the
•< wires and position of zero.
[ Tightened the base clamp.

T

20-079 W. /

{2o~o58 E. -i
>•.

IO. IO

NO

20-081 W. /

- 3-54

Polaris blurred.

i5 o

R

- 3-53

1 8. o

T .

r 20-174 W. 1
M M 4 (r

— 3 - 10

7

5. o

T

1I9-986E. I

r 20- 104 W. T
M.JlJ L.

- 6-35

10. 6

R

L2o-o33E. J

— 4-47

l5. A

NO

5 Urste Minoris S P. 0 Canis

- 5-23

1 5.33
1 8. 3o

XO

T

Cephei 5i « Canis

(-20-133 W. -i
M M 4 t • .'.

- 3-io

- 4'78

g

T

L 20-007 I^- j

— 2-o3

16.37
18 o

R
NI

A Ursa; Minoris S.P. o Canis Minoris

— 2 -2O
- 2-75

\ very faint.

23. 0

T

M. M 20-090 W

- 7'OS

M. M. boiling.

9

5. o

T

{2o*o5o W. i
1

- 7-36

0. 54

R

20 • 084 E. J

- 8-65

14. 58

NO

- 6-66

liain and clouds.

1 5. 24

5 o

NO
T

Cephei 5i e Canis
M. JT. 20-057 E

- 5-oi
— 7 - 20

Rain.

9.54

NO

Polaris v Piscium

- 5-29

Kain and cloud.

TABLE III. — AZIMUTH ERROR OF TH.E TRANSIT INSTRUMENT (continued).

77

Day.

Approx.
Local
Mean
Time.

Observer.

Stars or Meridian Mark.

Apparent
Error of
Azimuth.

Remarks.

1874.
November i o

12

•

i3

•4

.5
16

i?
iS

21

22

h in

19. 3o

5. o

9.48
19. o

5. o

9.45
14.44
i5. i3
16. 25
19. o

6. o

9.41

14. 48
i5. 9
18. o

5. 3o
9.43
i5. 1.5
16. i5
19. 3o

9.33
)8. o

9.29
20. o

5. 3o
19. o

18. 3o
19. o

5. o
9. 20
14. 6
14. 34

T
T

u
I

HI

T
t
11
K

n

NI

NI

T
NO
T
T

HI

NI

xo

R
K
NI

U
XI

JC

T

XI
NJ

M
T

Itl

T

SO

xo

r zo- :3o \V. T
M.M.-I ^

//

- 4-89
— 6-24

- 6-47
- 3-7.

- 4-78

- 1-16

+ o-53
- o-38
- 1-07
+ i-i3

- 3-37

- 0-72
+ 0-29
+ 0-37

O'OO

- 2-53
— 0-95
- 1-54.
- o-97
- 0-39

- i'?3
+ i -41

- 1-08
+ 1-75

- 2-08
+ 0-06

— i -01
- 1-80
- 1-57

•+• O- 12
+ I-39
+ 1-89

Very cloudy.
Rain.

Liquid cement was poured under
the piers.

1 20-017 E. ' '

r 2o-o3o K. T
M. M.-i L.

1 2o-ii3 W. J
Polaris v Piscium

M. M. 2o-i6o\V. ... .

( 2O ' 1?7 W. T

M.M.J L..

120-146 W. J

Cephei 5i 5 Geminoriun

A Urstc Minoris S.P. ^ Ar^us
M.M. 20-247 W

M.M.{20'I6SW-1.

1- 20' iyo W. J

MM. 20-229 w

M. M. 20-i83 W

Polaris e Piscium

\ Ursie Minoris P.P. a Canis Minoris

y>.^\. 20-222 W

M.M. 20-253 W -

M.M. 19-901 E

M. M . 19 ' 969 E

M. .M. 19-931 E

M.M. 19-950 K . . . .

V:.M. 20-197 W

M. M. 20-201 W.

Cepboi 5i f Canis

L 2

78

TRANSIT OF VENUS, 1874. HONOLULU.

Day.

Approx.
Local
Mean
Time.

Observer.

Stars or Meridian Mark.

Apparent
Error of
Azimuth.

Remarks.

1874.
November za

23

24

25

26

27

28

29
3o

December i

h m
15-43

19. o

5. o

9. 2
13.47

14. 4
14. 3 1
15.43

21. O

5. 3o
8.55
19. o

18. o
20.53

4. o
5. o
8. 5i
20. 3o

5. o

8-47
13.46
14-lS

i5.25
18. o

I«. 10

5. o

»

8.5i
14. 14
20. o

5. o
8.38
18. 3o

8.32
13.34
14. i
19. 3o

8.29

NO
T

NI

T
NO
T
H
R
R
NI

T
T

T

NI

T

NI
NI
NO
NI

NI
NO
R
R
R
T
T

T
NI
T
NO
T

NI
K

T

NO
R
R
NI

T

//
+ °'77
+ 2-26

- i-57

+ 2-58
— 0-40

— I'OZ

+ 2-65
- i-95
+ 1-64

— 0-95
+ i-oo
+ o-23

+ 0-34
— 0-93

- i'74

+ 1-04
+ 0-74

— 0-16
+ 1-09
+ 1-41

+ °'97
+ 0-34

+ 2-09

- 2-58

+ o-oi
+ I'll

+ 1-39

+ i • 16
+ o-38
+ i-75

+ i-53
- 2-o3
- o-73
- z-i3

+ 0-18

i

Polaris boiling.
Bad observation of S.

M. M. boiling.

Cephei 5i faint.

Polaris faint.

Polaris blurred.
S faint.
Cephei 5i very faint.

MM 20" 270 W

M.M. 20-203W.1

M.M. 20-203W.J

e XJrese Minoris S.F. j8 Orionis

Cephei Si € Canis

M. M. 20 • 260 W

M.M. 20-216 \V

M. M. 20* 23? W

M.M 20-241 W

M.M. 20-205 W. •>

M.M. 20-207 W. *

M.M. 20*25o W

M.M. 20-236 W

8 TJrsae Minoris S.P. y Geminorum

M.M. 20-281 W. -i

M.M. 20-271 W. 1
M.M. 20-197 W. -i

M.M. 20-193 W. •*

M.M. 20- 266 W.

M.M. 20- 263 W

M.M. 19-915 E

Polaris 6 Ceti

M.M. 19-986 E

TABLE III. — AZIMUTH ERROR OF THE TRANSIT INSTRUMENT (continued).

79

V

Day.

Appro*.
Local
Mean
Time.

Observer.

Stars or Meridian Mark.

Apparent
Error of
Azimuth.

Remarks.

1874.

h m
i3 ^n

//

8 blurred

1 3 5o

Cephei 5i v Geiuinorum

+ 2-o5

Cephei 5i blurred.

T

r, 9-964 K -,

— 0-45

5. 3o

T

I 2o-238 W. /
M.M./I9-98lE- I.

1

— I ' 06

1 3. 26

R

I 20'2l3 W. J

5 TJrsse Minoris S.P. . v Geminorum

- 2-58

8 faint and unsteady.

13.55

K

+ 0-89

i5. 4

R

+ i -20

IQ. O

T

M.Mr. 19-967 W

— 0-84

3

5.20

T

M.M. IQ-Q72 W. .

— o-o5

8. 23

T

Polaris £ Piscium

+ 1*71

jo. o

T

M.M. 19-931 E

+ i-36

«
5. o

HI

M. M. 1 9 • 974 E

— o* o5

8.25

NO

Polaris v Piscium

+ 2-68

i3. 18

R

8 Ursjs Minoris S.P. 77 Geminorum . . .

+ 0*00

1 3. 4.7

R

+ 2*QI

18.45

NI

M.M. 19-917 E. -i

+ 1'26

5

»

8. 14
i3. i3

NI

R

NO

M.M. 19-917 E. J

Polaris v Piscium
S Ursa: Minoris S.P. j8 Canis

+ 2-18

+ 2-57

IQ. O

T

M.M.jI9'9i°E- I.

+ 2* 26

6

5. 10

T

I 20- 296 W. J

{10' 944 E. 1
1

+ o'5i

8. ii

T

20-260 W. J

4- 1-84

21. O

NI

M.M. 20-286 W

+ I -80

5. 3o

NI

M. M. 20 •' 279 W

+ i-36

8. 7

R

+ 2-38

10. 25

NI

M.M. 2o'3i3W

+ 3-27

8

5. 3o

NI

M.M. 2o-3oi W

+ 2-59

8. 3

NO

Polaris £ Piscium

+ 3-84

14. 39

T

\ Ursae Minoris S.P. 6 Cancri

+ °'94

x faint

22. O

NI

M. M. 20- 296 W

+ 2'3l

o

6. 0

NI

M.M. 20- 299 W

+ 2-42

7.59

NO

Polaris 6 Ceti

+ 2-28

12. 5?

R

8 Ursaj Minoris S.P. T; Geminorum

+ 3-07

19. 3o

NI

M.M. 20-324 W

+ 3-83

80

TRANSIT OF VENUS, 1874. HONOLULU.

Day.

Approx.
Local
Mean
Time.

i_

E
>

i

.C
O

Stars or Meridian Mark.

Apparent
Krror of
Azimuth.

r
Bemarke.

1874.

5 o

M M 20-289 W

n
+ 1-86

12 53

+ 2-23

19. 3o

NI

•20-332 W. I

M M 4 }• ..

+ 4-12

5 o

T

I 19-886 E. /

r 20- 287 W. -i
M M i \-

+ 1-89

7 So

NO

l 19-924 K. J
Polaris 8 Ceti

+ 4- 34

It

5 UrssG Miiioris S.P. v Orionis

+ 5 ' 01

NI

M. M. 19-879

+ 4' 5o

M. M. boiling.

5 o

T

AI M 19-928 E

+ i'So

It

Polaris 6 Ceti

+ 4' 27

21. O

NI

M. M 19-883 E

+ 4'^4

i3

A 3o

NO

M M 19-884 E

+ 4-28

*

T

+ 7'55

4. 3o

E

{IQ'872 E. T
\- ..

+ 4 ' : 7

7. 3q

It

2o-3i6W. J

+ 6 '07

15

5. o

NO

M M 19-880 E

+ 4'5o

M. 11. boilin^.

7. 34-

NO

Polaris 0 Ceti . . .

+ 6'22

12. 34

It

+ 4-33

IQ. O

NI

M M 19-850 E. . .

+ 6 ' 10

16

12. 3o

NO

+ 7'iS

S blurred.

1 3. o

NO

+ 7 ''?

Cephei 5i blurred.

10. O

NI

MM 10*8471^

+ 6-36

17

5 o

NI

M M 19-878 E

+ 4.' 62

7. 3o

NO

+ 7*82

Polaris faint.

12 56

It

+ y-63

14. 3

B

A, Ursae Minoris S.P. 1 5 Arffus

+ 6*32

10. O

NI

M.M. 19-839 E

+ 6-81

18

7.23

IQ. O

R

T

Polaris TJ Piscium
M.M.jI9'825K' ]..

+ 8-o5

+ 7' 77

19

12. 17

NO

Uo-397 W. J
5 Urssc Minoris S.P. . y Geminorum

+ 3'6i

12.47

NO

+ 8 -08

Cfphei 5 1 llarin0".

20

5. o

NO

M.M. 2o-35o W. . .

12. 14

. NO

5 Ursac Minoris S.P. )3 Canis

o blurred.

12- 44

NO

Cepht/i Si 0 Canis

TABLE III. — AZIMUTH ERROR OP THE TRANSIT INSTRUMENT (continued).

81

Day.

Approx.
Local
Mean
Time.

Observer.

Stars or Meridian Mark.

Apparent
Error of
Azimuth.

Remarks.

1874.
December 21

22
23

24
25

26

27

2g
29

3o

3i

iS75.
January i

5. 3o

12. 39

13.49
20. o

19. o

5. 3o
19. o

5. 3o
i3. 38

19. o

5. 3o

5. o
1 8. 3o

5.25
17. 3o
iS.45

5. 3o
6. 39
ii. 38
12. 9
1 8. So
18. 55

5.25

12. 4

1 3. 14
18. 3z
19. o

5. 3o
6.35
18.40
19. o

11.27
ii. 57

XI

T
T
XI

f

T
T

SI

T
XI

XI
K
XI

T
BO

xo

T
T

XI
H

B
XO

xo

It
It

T
T

XO
NO

r2o-3o5 AV. i
M. M .J. [

//
+ 2-73

+ 5-19
+ 5-36
+ 6-14

+ 5-40

-t- 2- II

+ 3-38

+ 2-82
+ 4-95

+ 2-87
+ 2-48

+ 2-00
+ 3-72
+ 2-90

+ 2-88

+ 0-48
+ 3-34
+ 4-76
+ 4' 7°
+ 4-86
+ 3-72

+ 1-24
+ 2-40
+ 3-32

+ 4'24
+ 4'66

+ 1-64
+ 2-43
+ 6-02
+ 4-56

+ 5-o5
+ 5-21

M. M. boiling.

M. M. boiling.
M.M. boiling.

M. M. boiling.

("Three or four slight earth-
\ quake shocks.
M. M. boiling.

M.M. boiling.
Cephei 5i faint.
M M. boiling.

M. M. boiling.

1 19-912 E. J
Cephei 5 1 C Gemiuyrum

M. M. 20 • 166 W

M.M. 20-353 VV.

r 20 -20 5 W. i
MM.-,1 L

L 19-924 E. J

M.M. 19-911 E

M.M. i9'9ioE . . .,

M.M./'9'924E- 1.

Uo-3o9W. /

M.ir.r°'297W-l..

1 19-930 E. J
M.M. 20-327 W

M.M. 20 -3 14 W

M.M. Iq-Ql5 .

M.M. 19- 959 E

Polaris 20 Ceti . ...

5 tTrgse Minoris S.P. rj Geminorum

Cephei 5i 0 Canis

M. M. 1 9 • 901 E

M.M. 19-946 E

Cephei 5i y Canis

\ Ursac Minoris S.P. o Cauis Minoris

Polaris S.P 0 Virginis

M.M. 19-885 E

Polaris 0 Ceti

Polaris S.P f Virginis . . . .

M.M. 19-888

5 Ursae Minoris S.P. v (Jeminorum

82

TRANSIT OF VENUS, 1874. HONOLULU.

Day.

Approx.
Local
Mean
Time.

Observer.

Stars or Meridian Mark.

Apparent
Error of
Azimuth.

Remarks.

i875.
January i

18. AI

Polaris S P T Bootis

it

18 So

MM. 19-879 E

+ 5-12

2

5. 3o

R

M.M. I9'936E

•f I * 07

+ 4.' ?6

ii S3

R

+ 6*01

18. 37

T

Polaris S.P T Virginis

+ 6-85

3

5. 3o

T

{iq'o3o E. T
\- ..

4- 2*4.2

1 8. 20

•

20-311 W. /
Polaris S.P f Virginis

+ 5-o5

Polaris blurred.

18.26

R

M.M. i9'868E

+ 5-86

5. 3o

R

M.M. 19- 885 E

+ 4-90

M. M. boiling.

5. 56

R

+ 6-55

18. i5

R

Polaris S.P 9 Virginis

+ 5-33

18. 3o

R

M.M. 19- 854 E

+ 6-64

5

5. 3o

T

M.M. IQ-938E

+ 1-97

6. 12

T

+ 4-27

II. 12

R

S tJrssc Minoris S.P. TJ Geminorum

+ 5'49

11.41

U

+' 4/87

6

S.40

R

{IQ-Q32 E. i
I,.

+ 2-59

6. 4

R

20-320 W. J

+ 3-91

n. 17

T

5 Ursse Minoris S.P. y Geminorum

+ 6-o5

11.37

T

Cephei Si 6 Cunis

+ 5-62

18. 7

R

Polaris S P 6 Virginis

+ 4- 52

18. 3o

R

M.M. 20-363 W.'

+ 5-24

7

5. 40

T

M.M. 20- 345 W

+ 4-22

5.42

T

18. 5

T

Polaris S.P Spica

+ 6* ^2

18. 3o

T

M. M. 20-399 W

-f 7* 26

8

S. 3o

m

M. M. 20- 322 W

+ 2" QO

6. o

NI

+ 3-57

18. o

T

Polaris S.P o Virginis

+ 5 *O2

Polaris blurred.

18. 3o

T

M.M. 20-378 W

+ 6p 14.

M. M. boiling.

9

11.25

T

-i- A.' 4-0

12. 8

17.55

T
R

A Ursa; Minoris S.P. a Cam's Minoris
Polaris S.P S Virginis

+ 4'7*

1 8. 3o

R

M. M. 20-344 W .'

10

S.io

T

rzo-285 W. •)
M. M J I ...

1 19-955 E. J

TABLE III. — AZIMUTH ERROR OP THE* TRANSIT INSTRUMENT (continued).

83

Day.

Approx.
Local
Mean
Time.

Observer.

Stars or Meridian Mark.

Apparent
Error of
Azimuth.

Remarks.

1875.
January 10

II

12

i3

'4

i5

16

>7
18

h m
10. 5?
II. 22

17.54

18. 5o

s:45

5. 5o
10. 48
ii. 18

17.48

5. 5o

17.43
18.40

5. 5o
5. So
17.40
18. 35
19. o
19. 10

4.3o
5. 36
1 8. So

17. 3i
18. 35

5.25

10.33
11. 3

17. 3o

5. o
5.39
10. 33
10.53

5. o

5.20

5.25

10. 2O

10. 5o
19. o

B

R
T
T

T
T
R
R

T

R
R
R

T
T
R
R
R
R

R
R
NI

R
R

T

R
R

NI

NI
NI
R
R

NI

NI
NI
R
R
NI

//

+ 3"- 02
+ 3-29
+ 3-86
-t- 5-24

+ 2-48
+ 3-6i

+ 5-42

+ 4' 7°
-i- 4-65

+ 3-04
+ 5-65
+ 5-35

+ 2-14
+• 2-90
+ 5-56

+ 5-07

+ i-75
+ 2-08
+ 3-66

+ i-65

+ i-75

— o-5o

— i -06
+ o-33
— 0-04

+ 0-25

- i-38

+ O'2O

+ o'8o
- i-37

- 0-52

- i-Si
+ i-ii

+ 0-81
+ 3-o5

M. M. boiling.

M. M. boiling.
M. M. boiling.

•

M. M. boiling.
M. M. boiling.

Polaris S P C Virginis *

MM 20'36iW

M M 2o-3io W .

8 Ursae Minoris S.P. t\ Geminorum

Polaris S P ... Spies

M. M. 2o-3i8 W

Polaris S P 0 Vir<*inis . ...

MM 20- 359 W

M.M. 2o-3oi W

Polaris 9 Ceti

Polaris S.P 9 Virginis

M.M. 20-353W. ~|
MM 2o-38oW >

M.M. 19-849 E. J
MM 20 • 294 W H

M M 20-328 W

Polaris S P « Virginis

MM 20- 294 W

{20-254 W. i
L

19-976 E. J

Polaris S P Cephei 5 1 ....

MM 20-266

r 20'x3i W. I
jfj^J L

Li9'984E. J

MM 19-986 E

M

84

TRANSIT OF VENUS, 1874. HONOLULU.

Bay.

Approx.
Local
Mean
Time.

Observer.

Stars or Meridian Mark.

Apparent
Error of
Azimuth.

Kcinarks.

1875.

h m

5 35

"

"
— 3-47

5 4.5

T

MM 20-o53 E

- 5-o6

{M.M. slowly oscillating 2" or

- i-5o

3" sideways.

T

— I ' 12,

ii. 35

T

+ I ' 72

A boiling.

5 ii

T

V?5

5.20

T

{20*040 E. T
\- -.

- 4'36

jo. 1 6

U

20-181 W. /

- 2'8l

10. 42

U

— 2' 1 I

18. 55

T

M. M. 2o-o38 E

— 4' 16

21

5. 40

NI

MM 20-065 E

5'?3

1 1. 4-5

T

3- 24.

22

5. 40

K

MM 20 • 1 68 W

1 1. 40

T

3-89

23

5.40

NI

M M 20- 145 W .

10. 5

K

— 3- 18

10. 3o

K

3'"i

24

6. 10

It

r 20 -i 87 W. T
M M. J }•

9-55

NO

1 20-034 E. -I

j 99
2- 33

IO. 25

NO

- ti- 3i

16. 36

It

Polaris S.P 3i Coma;

25

5.35

T

{20 • i go W. i
L . .

3-S2

16. 5i

T

2o-o3oE. J
Polaris S P ... 6 Virginis

I'25

18. So

NO

MM. 20-236 W

26

5. 5o

NI

M.M. 20-205W

— 3-07

10. 18
16.54

NO
T

Cephei 5i e Canis
Polaris S P ( Virginis

— 0-09
— i -3i

19. 10

K

M M 19-984 E

1-18

27

5.55
9-44

NI
K

M.M. 20-010 E

- 2-63

10. 14

U

16.45

T

28

19. 20

5. 5o

NO
XI

M.M. 20-263 W

M.M.r-°'"7W-\.

+ 0-23

- i-85

1 19-996 E. 1

TABLE III. — AZIMUTH BKROR OF THE TRANSIT INSTRUMENT (continued}. 85

Day.

Approx.
Local
.Mean
Time.

Observer.

Stars or Meridian Mark.

Apparent
Error of

Azimuth.

Hemarks.

1875.

q 4.5

n

O'OO

5 blurred.

vo

+ 2-69

1 8. 40

T

M. M 20*261 W

•f O- 12

M.M. bailing.

29

5. So

Nl

M.M. 20-224 \v

- I'94

o- 28

3o

1 8. 3o

5. 5o

T
KJ

M. M. 20-272 w

M. .M. 19-996 E

+ 0-76

- i-85

. -i . ^p.

M. M. boiling.

9. 3l

10. o

NO

Cephei 5i 0 Canis
MM 1 9 • 9 3 9

+ 3-40
+ i'36

^ ,

5 5o

f IO* QQO K. "1

M.M. 4 I..

i-38

I 20-237 W. J
5 Ur^se Almoris S P )8 Canis

9. 29

0 <8

i j • -7-

1 8 3o

AI V. i9'945 K

February i

5.35

XI

M."M. 20-062 K

- 5-56
4*66

9. 24

n $A

9. .^4
/; -.

MM 20 '07 1 E

- S'A^

A faint.

3

6 o

AT AI "0-066 E

- 1 "70

Cephei 5 1 & Caiiis

6

5 40

r2o-i83 W. i
If.M.-l \-

4 J4

8 58

NO

L 10-0378. J

M.M. 20-212 W

M. M. very steady.

VO

M M. 20 • 207 W

o 33

NO

Cephei 5i y Geminorum

NO

M M 20-211 W

6 i

XO

MM 20-218 W

8. 58

T

T

M.M. 20-234 W
5 Ursai Minoris S.P 5 Oriouis

+ o'43

9 28

T

9 36

T

T

M M 20-255 W

10. 28

T

M. M. 20- 281 W

10. 37

T

\ Ursac Minoris S.P. 3 T:uiri

+ 1-32

M 2

86

TRANSIT OF VENUS, 1874. HONOLULU.

Day.

Approx.
Local
Mean
Time.

Stars or Meridian Mark.

Apparent
Error of
Azimuth.

Remarks.

i87S.
February 7

io.56

15. 54

16. i
1 6. 29

5.54

8. 3o
8.55

9. o
10. 28
10. 3g
10.58
15.28 .
iS.SS
.16. 2

8.26
8. Si

8.58
9.22
9.29
9.55

10. 22
10. 30

15.35

15. 52

16. 4

T
R
B

JU

T
T
T
B
B
B

Hi

NI
NI

B

R

R

NI

NI

NI

NI

NI

T

9

T

M.M. 20-281 W
M.M. 2o-3o3 W
Polaris S.P
M.M. 20-260 W...

Tauri

71 Eridani .

f 20 • 248 W. i

M.M.4 [

I 19- 974 E. 1

M.M. 20-270 W. ..
5 TJrsae Minoris S.P.

M.M. 20-281 W

M.M. 20- 272 W

A TJrsae Minoris S.P. o1 Eridani

M.M. 20-281 W

M.M. 20-273 W

Polaris S.P o1 Eridani

M.M. 20-281 W. .

M.M. 20-271 W

8 Ursae Miuoris S.P. o1 Eridani .

M.M. 20-279 W

Cephei Si y Tauri . . .

M.M. 20-289 W

M.M. 20-248W

A Ursse Minoris S.P. 7 Tauri . . .

M.M. 20-285 W

M.M. 20-325 W

Polaris S.P a Serpentis .

M.M. 2o-3i5 W. .

2-79

i-o3

+ 0-48

+ 0-82

-f 3-24

TABLE IV. — MERIDIONAL TRANSITS of STARS and of the MOON observed at HONOLULU, and INFERRED

ERROR of the TRANSIT-CLOCK.

Day.

Reading and
Position of
Micrometer.
[Adopted
Reading for

Zero of
Collimation.]

Object observed

and
(Number of Wires).

Mean observed

Clock-Time of

Transit over the

Center Wire.

Seconds
of True
Transit
over the
Meridian.

Seconds

of Star's

Assumed

Apparent

R. A.

Clock

apparently

Slow.

1874.
October 3

20-825 W.
21 -029 E.
20 • ooo W.

A Ursae Minoris
A Ursae Minoris
p Capricorn! . . .

19. 48. 17-60
19. 52. 57-60
20.21. 39-02

42-02
42-3i
38-95

46-08
46-08
41-94

4-06

3-77
3-99

TABLE IV. — MERIDIONAL TRANSITS (continued').

87

Day.

Observer.

Reading and
Position of
Micrometer.
[Adopted
Reading for
Zero of
Collimation.]

Object observed
and
(Number of Wires).

Mean observed
Clock-Time of
Transit over the
Center Wire.

Seconds
of True
Transit
over the
Meridian.

Seconds
of Star's
Assumed
Appaient
R. A.

Clock
apparently
Slow.

1874.
October 3

20 Ceti

h in »

o. 46. 29*68

s

3i-i3

H

37-15

6 -02

17-750 E

i. 7. 28 *oo

i5-oo

21-22

6-22

17-750 W

iS-oi

21'22

6-21

[20-176]

c Pisciuin

o. 56. o" 06

9-75

27-36

17-61

21 *5oo W

3-34

2I'l3

17* 7Q

Polaris

i. i 7. 4' 60

3-34

2I'l3

17-79

5

[20-218]

to -37 5 E

19. 46. 23 'oo

16-06

43-27

27-2I

io- 3^5 "\y

A Ursse Minoris

19. 52. 3 * oo

i6-o5

43-27

27-22

20. i3. 32*66

3i-93

58-33

26-40

i. i3. 8-71

52-45

21 -2O

28-75

i. 34. 25'54

26-62

55-53

28-9I

NI

[20-218]

t

19.49. 5o'o6

37-33

40-67

3-34

20. 21. 39*56

39-55

42-88

3-33

i5

NO

[20-265]
20-233 W

o. 56. io* 14

9-92

27-43

i7-5i

i. i3. 56-8a

4-93

22-45

17-52

[20-302]
--o-z33 ^y

5 Ursae Minoris S.P

6. 12. lO'OO

19-95

38-04

18-00

20-233 W

6. 3o. io* 66

10-43

28-49

18-06

23-000 W

6. 37. 3i-67

54-80

12* QO

18-10

Cephei 5i

6. 44. 28' 72

54-80

12' QO

18- io

2O-233 K

6.53.23'48

24- 14

42* 1 3

17-00

[20-316]

Moon I

19. 28. 41 * 12

40-45

[20-861

17

IO. 4.7. 4.0*24.

48-60

q-54

19. So. 58-66

58-04

18*80

20*85

"

19. 54. 36* 70

36-o6

56-0?

20. 4. 29- 64

29-23

50'2I

20*08

a2 Capricorn!

20. io. 45*48

41 '97

6*o±

21 *o5

2O. 21. 22-62

22-07

4-2*73

20* 66

20. 26. 53-28

52-96

i3-54

20-58

20 33. 28-62

28 -3o

8 Ursse Minoris S P

6 12. 5-25

i5-i8

37*i3

6.21. 9-88

Q- 6q

3i'6i

21 *Q2

6.40. 45-67

52-22

14-00

2I*78

6. 53.20-88

20*40

42-18

21 '78

[20'003]

October 17. The Azimuth Error from 19''. to 2ih. has been taken — 8"-3.
„ 3) 8" i, 24*-6, 4i'-o, 57"9, i3"*9.

88

TRANSIT OF VENUS, 1874. HONOLULU.

Day.

Observer.

Reading and
Position of
Micrometer.
[Adopted
Reading for
Zero of
Collimation.]

Object observed
and
(Number of Wires).

Mean observed
Clock-Time of
Transit over the
Center Wire.

Seconds
of True
Transit
over the

Meridian.

Seconds
of Star's
Assumed
Apparent
II. A.

Clock
nppareutly
Slow.

1874.
October 1 8

T

r

0 Aquiloe (3)

h in s

27-28

S

20 i 3 35-64.

35*i3

58- 14

23 • or

ra3'oi1

67 Ceti

23-53

£ Ceti

3o-8S

v Ceti

2 28 55 -70

55-4.2

18-92

z3- 5o

5 Ceti . . ....

4'73

23-64

y- Ceti

2. 36. 26-38

26 ' oo

49' ^4

23-45

35-40

23- S6

10

NO

[2O-OO6]
2O-OOO E.

3*54

21. 24. 55 ' 62

55- 12

16 Pegasi (3)

5?-o5

a Aquarii

21. 58. 56-96

56*64

21 ' 26

24- 62

i Pegasi

22. O. 46' 26

46 * 16

1 1 - o5

24-80

B Aquarii

22. Q. AO' 58

*
4.0 • 10

i3*79

24- 60

y Aquarii

22, 14. 47 ' 12

4.6" 7O

n-55

24-76

22. 23. 37- IO

36-70

i-53

24-83

22. 2S. 3l ' IO

30-78

55-6o

24-82

T

2O'2O2 E.

i. i3. 10' 75

57-25

221 25

25 ' OO

20

it

[20'0l3]

20 • ooo E.

22. 2O 5 I ' 06

50-73

[26-72!

£ Pegasi

22. 34.46-56

46 -40

i3-3o

26 - 90

22. 5o. 1 8 - 32

17-88

26-57

22.58. 5-n

4,'OS

3 1 -70

26-81

N-O

2O'25o E.

i. i3. 18*40

55-37

22-09

26-72

20 • ooo E.

i. 38. 20-88

20-76

47-68

26-92

21

T

[20-024]
20 • ooo E.

22. 9. 45 '46

45 ' 22

13-76

28-54

22. 14. 43 *O8

42" 89

ii-53

28* 64

<r Aquarii

22.23. 33'22

32-96

i-5i

28-55

T) Aquarii

22. 28. 27' l6

26-97

55-58

28-61

fj. Pegnsi

22. 43. 29 ' 22

29 * 2O

57-89

28-69

A. Aquarii

22. 45. 36* 90

36-66

5-24

28-58

22 5o. 16*14

i5-78

28-66

Moon I.

23. l6. 33*92

33*68

[28-66]

18-023 E.

Polaris

i. 7.25*36

21 ' 02

27-28

18-664 W.

i. 16. 19*4^

54-63

21 ' 02

NO

20 • ooo W.

59-23

28-68

20*4.5

Cephei 5i -

6 40. 42 '88

4.5-08

i6-i5

3o* 17

[20-032]

October 1 8. }> , 9"6, 26"-o, , . Azimuth Error, —6" -6.

„ 19. J 24s-5, 39s-6, 55"'7, ns-4, 26"-8. Good observation.

„ 20. )) 2i"-o, 36s- 1, 5i'"o, 6"-2, 2o!'9. Cloudy; good observation.

„ 21. }) 4*'o, 19"' i, 34s-o, 49"o, 3S'4- Air very still.

October 19. Azimuth Error, — 8" -7.

TABLE IV. — MERIDIONAL TRANSITS (contin'ued).

89

Day.

^

1

Heading and
Position of
Micromotor.
[Adopted
Heading for
Zero of
Collimation.]

Object observed
and
(Number of Wires).

Mean observed
Clock-Time of
Transit over the
Center Wire.

Seconds
of True
Transit
over the
Meridian.

Seconds
of Star's
Assumed
Apparent
R. A.

Clock
apparently-
Slow.

1874.

T

19-208 W.

li in s

1.14. 54'25

5o* 71

21 *8l

3i * 10

i. 34. 25-38

25-o5

55 * 70

3o-65

23

T

[20'033]

20 • ooo W.

o. 18. 27-72

27'30

5o* 70

32-3i

12 Ccti

o. 23. 7-64

7'29

3o* 60

32*3i

€ Andromeda?

o. 3i. 74* 84

24- 5o

57*08

32*40

£ Ceti

o. 36. 47 • 10

19* 18

32'4Q

o. 41. 39-73

11-84

20 Ceti

0.46. 5-34

4' 00

37-24

32-25

o. 49. 17-00

1 6' 77

32*28

I . 5. 22 "40

22' OQ

r32*4oi

16-379 W.

I. 22. 21 ' 5o

5o*22

21 * 74

3i * 52

24

xo

[20-o35]

20 Ceti

0.46. 3-38

3'07

37*24

34* 1 7

o. 49. 1 5 '06

14' 76

40' o5

34*20

e IMscium

o. 55. 53-64.

53'34

27*47

34' 1 3

f 1'isciimi (3)

i. 6.38-35

38-o5

I2'l3

34-08

10' 07 3 W

Moon 11. (4)

2. 2. 57-30

57 *oo

'

[34-18!

25

[so-o36]

I. i3. 48-80

45 * 70

21 * 72

35-93

I. 34. 19* 80

IQ'78

55-72

35-04

26

T

[20-o33]
20 ' ooo E.

Polaris

J. 12. 24-42

36-98

21 * 72

NO

a Ccti

2.55. 6-84

6-85

44* 04

38-09

3. 3.5o-82

50-87

29' o3

38-16

3. i3. 22-56

2Z-63

38- ii

3. 17. 27 ' 2d

5-3o

38-i3

3. 23. 20-22

2O' 25

58-45

38-20

€ Krlduni

3. 26. 24-84

24* 80

2-81

38-ci

1 1 Tnuri

3. 32. 40-^4

40*41

)8-3o

37-o8

5 Kridnni

3. 36. 37*80

37*76

I 5 ' 02

38-i6

Moon IT

4. 10. 29 • 82

20*87

r38-i7i

K

Cephei 5 1

6. 39. 20*00

43-8l

18-89

35-08

6. 53. 4'3o

4*23

42*46

38-23

27

It

[20*039]
20 • ooo E.

Vohiris

T. 12, 32*4^

4.0* 57

21 * 60

16-16

55-73

3o*57

NO

5i-o8

3o* 69

30-78

3i-86

3o'84

> >

B. A. C. 1648
.Moon II

5. 12. 27-96

28*11

8-3o

40-19

5. 24 57*o8

57*i6

J7 ' 1 1

3o'o5

c ( )rionis

52-o8

3o*o8

[20*041]

October 23. j) 53*'4, 7" 5, 22" 5, 37"' i, 5i*-6. ( iood observation.

„ 24. j) 26"-5, , 57"-5, i2'-2, 27"-o. Cloudy; ruin.

., 26. > 57"'7, i3"-6, 29"-8, 46'-!, i'-8. Good oliservation.

„ 27. > 38"-5, 55"3, i2"-o, 29"- 1, 45"3. Altivli tremor.

90

TRANSIT OP VENUS, 1874. HONOLULU.

Day.

Observer.

Reading and
Position of
Micrometer.
[Adopted
Reading for
Zero of
Collimation.]

Object observed
and
(Number of Wires).

Mean observed
Clock-Time of
Transit over the
Center Wire.

Seconds
of True
Transit
over the
Meridian.

Seconds
of Star's
Assumed
Apparent
R. A.

Clock
apparently
Slow.

1874.
October 29

R

r

19-883 E.

Polaris (3)

h in s

i. 12 14' 33

37*58

S

S

v Piscium

i 34 12*34

5 5.7 A

Al'lA

November 4

it

2O-OOO E.

Cephei 5 1

4-0" I 8

2,3 • 27

20-063 E.

y Cams

6. 58. 32*3o

32-08

5

R

[io-o63]
20-o63 E.

€ Piscium (3)

o. 56. 58-i5

57-93

27*A8

3o'45

20-085 E.

i i3 42*80

AQ' 88

19*36

3o* 52

!~2O'o67l

14

NO

20-070 W.

23-69

1. • -7«

17-575 w.

Polaris (i)

i3-8o

R

20*070 W.

jS Canis

6. 17 8- 5o

8'AQ

3'5i

6 41 a3 * 3i

23 *OQ

28 * 10

5 'or

3*66

20-125 W.

A Ursse Minoris S.P

7.48. 56*5o

AA*88

iS

NO

[20-080]
20-080 W.

0 Capricorn!

20. 58. 5o* 3o

5o-25

53*98

V-?3

r^-77"i

21. 7. 3i '82

3i-8o

35P78

L-* 7/J
3 *o8

t Capricorn! '

21. l5. 12' l6

3*02

^ Capricorni

26-95

3o-65

•3 . -7O

6 Capricorni ... . .

3o-q5

34-67

7 . -o

& Aquarii

21. 24. 53*86

53-82

57-63

3*8i

21 3 I I" 08

4- 80

^•76

•

e Peeasi . .

21. 37. 57*98

S7-q5

i-85

6*7^

20-080 W.

?j Piscium

1 . 2A. 4-4 ' 1 2

16

T

[20*080]
20*080 E.

Moon I

21. So. A-58

6 Aquarii

22. 10. 9*40

i3-45

45 Aquarii

22, 12. I 3*42

l3'26

17* 5o

y Aquarii. . ,

7'Q1?

57-06

A1 I1!

7] Aquarii

22. 28. 5l'32

5l'I7

55-28

22. 35. 8-90

g- 75

0*86

20- 12,5 E.

Polaris

i. i3. 17*66

8*o3

i5-68

6»T?

oCeti....

45' i5

[20-080]
20*080 W

Polaris

5*8o

I'll

i 38 43*12

A • KT

3q-38

e Trianguli

i. 55. 35*34

35-10

5- 08

[20-081]

November 1 5. ]> 5i"-3, 7"-o, 23s- 1, 38"-8, 54"o. Daylight.
„ 1 6. } 34" -0,49s -2, 4"'7, 2os-o, 348'9. Air still.

TABLE IV. — MERIDIONAL TRANSITS (continued).

91

Day.

Observer.

Reading and
Position of
Micrometer.
[Adopted
Reading for
Zero of
Collimation.]

Object observed
and
(Number of Wires).

Mean observed
Clock-Time of
Transit over the
Centre Wire.

Seconds
of True
'Transit
over the
Meridian.

Seconds
of Stars
Assumed
Apparent
R. A.

Clock
apparently
Slow.

1874-
November 22

T

r

20" 080 W

h m a

2. o. 3 ' i 6

•

2' 02

8

7-88

67 Ceti (V) .

4O'37

45-33

£2 Ceti

26* 22

3l* 12

v Ceti (4)

2. 20. IA'A2

14.* 23

IQ* 2O

5 Ceti

2. 33. O'2O

o*o3

5*oo

-/- Ceti

2. 36. 45* 12

4Q-84

14-' 34.

IQ'4.3

4.7* 5 1

5*ii

3. 32. 53-00

52-76

Mooti II

3. 35.23-04

22 '80

NO

20-857 W

5 Ursge Minoris S.P.

6. 1 3. 6*00

24-35

20 • 080 W

6. 21. 27 • 82

32-6q

5'07

Cephei 5i

6. 4.1. 3o* 3?

25-85

3f42

5-57

6. 53. 38-i8

38-17

43-25

5*o8

£ Ar^us

7. 43. 57' 18

57-I6

1-36

5*20

2O'75o W

A. Ursse Minoris S P

36-36

36-62

23

NO

i. 1 3. 3o' 29

12*06

12-52

20 • 080 W

42* 3o

4.7-82

5-52

T

20 • 080 "W

e Tauri

5-37

a Tauri

4. 28 40* 1 8

45-37

5-37

r Tauri

4. 34. 39*70

3o-5o

45 *O2

5-52

^ Eridani (4)

4. ^Q. IO'46

io*33

i5'73

5 -40

Moon II

4. 41. 5o* 5o

5o*2Q

rs-49i

B. A. C: i5i8

4. 48. 34' oo

33-70

39-28

5 '40

k Tauri (4)

4. 5o. 25 * SQ

25*38

3o*oo

5-52

e Ursse Majoris S.P

4. 58. 38*12

30'20

44 *OT

4' 72

Rigel

5. 8.26-88

26' 77

32*41

5-64

& Tauri

5. 1 8. 18-54

i8*3i

23* 06

5-65

R

21-750 W

24*o5

i-o5

20 • 080 W

6. 3o. 24- 66

5-i5

Cephei 5i

6. 41. 37-78

27-88

3i-o5

4*07

20 • 080 \V

6. 53. 37-92

37-89

43-28

5-39

753 i ' 20

35*66

— 6-46

20' 080 W

8. 9. 38'6o

38-45

4 4 ' O I

5-56

26

NO

[20-083]
20*000 W

i. i3. 24-86

8-48

lO'oS

2-5o

20 • 080 W

I. 34.. 4.0*4.8

4.0* 23

55-76

6-53

27

NO

[20-089]
20 • ooo W

Polans

i. i3. 24-57

3-26

10-33

7'°7

20-080 W.

v Piscium

I. 34. 40' IO

48-85

55-76

6-91

R

• 20-5oo W.

6. 12. 39'36

1 6 • 74.

22-86

6- 1«

20-080 W.

6. 3o. 23 ' 14

29-75

6-85

[20-091]

November 22. j) I. 2i»-5, 37"o, 53"-o, 9"'o, i4*-6. Good observation.

B II. 5i"-5, 7""2, 23" i, 39"-o, 54s-5. Correction for defective illumination, +oa-28.
„ 23. J II. i7»-8. 34"-!, 5o'-5, 78-o,23'-2. Tremor.

N

92

TRANSIT OF VENUS, 1874. HONOLULU.

Day.

Observer.

Heading and
Position of
Micrometer.
[Adopted
Heading for
Zero of
Colliination.]

Object observed
and
(Number of Wires).

Mean observed
Clock-Time of
Transit over the
Centre Wire.

Seconds
of True
Transit
over the
Meridian.

Seconds
of Stars
Assumed
Apparent
K. A.

Clock
apparently
Slow.

1874.
November 27

K

r

h in &

6. 41 36' 67

s
25-22

33-72

8-5o

20 • 080 AV

6. 53 36-44

36-36

43*38

20-080 W.

Procyon

7. 32. 38*8o

38-6o

45-65

7-o5

30' A7

T

20' 080 W.

Moon II,

Q. I. iS ' QO

18-72

[7-12!

83 Cancri (3)

52-QI

a Hydrge (4)

in - 16

26-26

7* Jo

£ Leonis

9-25 5'l6

5 "oo

7"°7

o Leonis

21 ' 1 1

"8'27

7* 16

9 38 37*98

3?-77

44" 88

9 45 3i '68

3I-46

38-73

7'27

9 53 28-82

28-61

35-91

7* 24.

28

T

20-080 W.

i i3 7-68

Q-66

7-57

67 Ceti

2 10 38' 18

45 * 33

7-3o

XO

•17-820 "VV

26-32

20*080 W

Procyon

7 32 38*5o

38-"6

45-68

11

20*080 W

9 34 21 • i 8

28-30

7-28

9 38 37*98

37-78

9 45 3i • 78

3i-58

38*77

40- --8

[7*18]

5o'3i

57*56

•y' Leonis

10. 12. 57 * 36

57-J7

7 ' O4

99

It

[20-093]

58 '40

8-96

io*56

20 '080 W.

v PiscJum

i. 34 48 • 60

A8 ' 3d

55-75

T

20 • 080 E.

a Leonis (4)

34- <i

42*33

56-58

7-66

p .Leonis (4)

5-27

7-S3

34 Sextantis (4)

10 36 1-87

I * 71

Moon II

3o*25

f7*77l

8 Leonis

-

7*82

December i

T

[20-094]
20*080 E.

/3 Andromedse

i 236*14

S- 15

19*573 E.

Polaris (4)

o-35

7-58

T'»S

20 '080 PJ.

a Eridani

i 32 57*48

57*52

5-32

7-?0

/3 Arietis (4)

36*25

S *OZ

a Arietis (3)

i 59 59'88

59*66

T So

8 -23

v Ceti

1 1 ' 3o

S Ceti

56-89

S'02

8-i3

•y2 Ceti

41 • 82

NO

20 • ooo E.

3 Ui'sae Minoris S.P

.. i .42^

fi- IT

2.O* IOO E.

y3 Canis

4' 28

14 • **ta

S' II

[20*098]

jz .39

November 27. > 47»-3, 3"-o, ig'-o, 35"-o, 5os-3. JSad observation.
„ 28. }) ios-o, 24"9, 40" 5, 56'-o, ns-o. Limb unsteady.
it *9- }' is'o, i5s'4, 3o"4, 45*- 3, o'-o. Much tremor. Howling v.ind.

TABLE IV. — MERIDIONAL TRANSITS (continued).

93

Day.

( )bserver.

Heading and
Position of
Micrometer.

[Adopted
Beading for
Zero of
Collimation.]

Object observed
and
(Xumhor of Wires).

i

Mean observed
Clock-Time of
Transit over the
Centre Wire.

Seconds
of True
Transit
over the
Meridian.

Seconds
of Stui-s
Assumed
Apparent
R. A.

Clock
apparently
Slow.

1874.

v Geminorum

ll ill S

S

3z * 92

8* 20

Cepliei 5 1

35*07

5-5?

Moou II

T8-I81

19*643 K

5 Ursuj Minoris S P

6 12 43-85

l5'22

21-66

v Geniinorum (4)

32-95

8 - 14

y Geminorum

21 "55

20* 8?

8'32

Cephei 5 1

35-38

6- 13

£ Av<ru^ . .

2-65

8-25

rg-szi

[20* zoo]

22* 364 E

2-36

5-6o

3-33

v Piscium

I 3d. A 7 ' 32

55-73

8*64

77 Geminorum

6 7 ii -86

20*^3

S* 92

5 Ui'sac Minoris S.P

21-38

•y Geminorum

6 3o. 21*32

8*83

6 41 5*33

35*98

5

[20*I05]

e Piscium

o. 56. i8'38

l8'2O

27 ' 3d.

& Andromeda:

i. 2.35*18

34-86

Polaris

55-4.6

5-n

q*65

i. 3d. 4.6' 78

55-73

i. 38 38-S8

3S*6q

£ Arietis

1.4-7 35* 4.O

35-i5

I7'3l

20*55

o*3i

5 Ursae Minoris S.P

6. 17. 3*12

3*07

6. 21. 23*78

z3-58

33*01

0* A3

6. 56. 32-98

3z-78

0-4.3

3o-54

30* Q2

g-38

7. 32. 36* So

36-36

4.5-87

Q'5l

[iO ' I 06]

56-5z

4.- 56

8'C4.

i. 24. 38 • 12

37-87

Q'So

[20* 106]

o. 56. 17*58

I7'35

27*33

q*oS

7

I. 2. 3d.' 24

33*88

I. l3. 21 ' 22

54.* 14,

3-o8

0-84

I. 24. 38 '02

37*76

4.7-76

10*00

I. 3d.. 4.5 * Q2

4-5 ' 60

55-72

io-o3

1. 38.37*96

87-72

47-73

lO'OI

/3 Anetis

i. 4.7. 3d.' 56

34-27

44- 25

9-08

[20-107]

]) ig'-o, 33s-2, 47"
22-0,36-3, '

•7, (2"'4), i6"'4. One hour after sunrise -. limb bright and steady.

•o, 5" 7, 2O"o. Two hours after sunrise; limb very steady and fairly bright.

N 2

94

TRANSIT OF VENUS, 1874. HONOLULU.

Day.

Observer.

Reading and
Position of
Micrometer.
[Adopted
Beading for
Zero of
Collimation.]

Object observed
and
(Number of Wires).

Mean observed
Clock-Time of
Transit over the
Centre Wire.

Seconds
of True
Transit
over the
Meridian.

Seconds
of Stars
Assumed
Apparent
R. A.

Clock
apparently
Slow.

1874.
December 7

E

r
20-100 W.

a Arietis

h m s

i. 59. 58'O4

57-74

7-87

io-i3

£' Ceti ...-

2. 6.12-82

12-58

22-81

10-23

NO

2O- IOO W.

6 Leporis

o' o5

11*17

IO* 22

Rigel

5. 8.22-34

22* 26

32-62

io-36

ft Tauri (4)

5. 18. 14*07

i3-8i

24-24

10-43

5 Orionis

5. 25. 27 • 60

27-48

37-96

10*48

5.27. 3-76

3-72

I 3 * QA

IO* 22

5. 29. 42' 72

42 * 60

8-69

1O*34

5. 34. 58-36

58-43

52- 94

10* 26

5. 4.1. 40' 20

40-12

5° '44

10*32

16-41

26-74

10* 33

8

NO

2O- IOO W.

I

o. 3i. 46- 5o

46-19

56-8o

10-61

S Ceti

o. 37. 8' 3o

8-19

18-91

10-72

0

o. 42. i * Zi

i- 10

. 1 1 - 64

10-54

26-44

37*04

10" 60

o 56. 16-78

i6-56

27*32

10-76

j. 7. i * 5z

i-3o

I2'o3

10*73

20-125 W.

i. i3. 3-67

56*40

3-39

6 -90

2O- IOO W.

i. 24. 37 * 3o

37'o5

47* 7 ^

10-70

I. 34.. 4-5 * 12

44* 91

55-7I

io"8o

T

7. 2O. 12* 32

I2'l3

22-80

10-67

27*40

38-00

10* 60

7 32. 35-42

35-25

4.5 * 04

io* 60

•

Pollux

7. 37. 3o-o2

29-76

40-46

10-70

7 4.3 5i*o8

5 1 * 04.

2-80

10-86

20-569 W.

A Ursae Minoris S.P

7. AQ. 34" 60

i3-i8

18-94

5-76

20- 100 W.

7. 55.40-36

40*10

5o-85

10-75

•

8. 1 6. 2' 10

1-88

12-66

10-78

8. 3o. 58-oS

58-8i

9-54

10-73

NO

[20-107]
20* 100 W.

o* 71

n-63

1C' 02

20 Ceti

o. 46. 26* 54

26-35

37'o3

10-68

38-o3

48-75

10* 72

o. 56. 16-66

16-43

27-31

10*88

i. 2.33-54

33-i8

43' 09

10-81

^1 Piscium

i. 7. i ' 32

I *OQ

12 -O2

io' o3

20-006 W.

i. i3. 18-57

52-56

2-73

jo ' 17

20- too W.

0 Ceti

i. 17. 35-78

35-6i

46-66

1 1 'o5

i. 24. 37*12

36-86

47-75

IO' 8q

n

6. 7. IO'22

Q'Q2

2O1 64

io' 72

20-000 W.

6. ii. 58-20

IO'4-O

20- 3o

9* 9°

20- 100 W.

I * 04

12-54

IO' 60

[20-108]

TABLE IV. — MERIDIONAL TRANSITS (continued).

95

Day.

Observer

Reading and
Position of
Micrometer.
[Adopted
Reading for
Zero of
Collimation.]

Object observed
and
(Number of Wires).

Mean observed
Clock-Time of
Transit over the
Centre Wire.

Seconds
of True
Transit
over the
Meridian.

Seconds
of Stars
Assumed
Apparent
R. A.

Clock
apparently
Slow.

1874.
December 9

R

r
2O" IOO W.

h m »
6. 21. 22* 70

K
22-4I

33-10

S

IO' 6q

6. 48. 12-96

12-86

23-63

IO* 77

6. 53. 33-o6

33-07

43-65

10-58

y Canis Majoris

6.57.56-26

56-19

6-89

5 1 Geminorum

7. 6. 1-62

i-36

12-18

10-82

8 Geminorum

7. 12. 29-46

29-17

40-03

10*86

10

NO

20' ioo w.

4. 59. 59-96

59-98

11-19

1 1 '21

Kirrel

5. 8.21-36

21-29

32-65

u-36

/3 Tauri

5. 18. i3-32

l3'O2

24-28

ii * 26

5.26.26-82

26-70

38-oo

ii - 3o

5. 27. 2- 74

2 '74

13-97

II'23

5. 29. 41 - 84

41-73

52-98

ii-aS

5. 34. 5y -42

57-52

8-72

5.41. 39-34

39-28

50-48

II *2O

i Geminorum (4)

5. 56. 21 -oo

20-74

32-o3

1 1 *2Q

20-000 W.

S Ursae Minoris S.P

6. ii. 58-5?

10-98

20-14

Q' l6

14

K

[20-108]

20' ioo E.

22. 34. 40*08

40-06

rii-83i

22. 5o. 3i -82

3i-93

4.3-72

y Piscium

23. 10. 28-62

28-47

40-33

11*86

23.20. 18-98

18-85

3o-78

ii'83

i. z.32-38

31-96

43-93

II * 07

2O-25O E.

1. 13. 29-86

46-93

58 -67

1 1 * 74-

2O* IOO E.

i. 24.. 35 * 02

35-69

4.7" 71

i. 34.43-68

43-53

55-67

1.38. 35-88

35-71

4.7' 60

n-88

i. 47. 3z' 60

32-33

44/2I

ii-88

i. 59. 56* 10

55-8o

7*8A

i5

NO

[20-108]
20- ioo E.

22. 58. 18-92

i8-75

3i-iS

12*4.3

23. 10. 9- 10

Q- OQ

21 "4.3

12' 34.

23. 20. 18-46

18-39

3o* 77

12*38

B. A. C. 8184

23. 22. 5 1 '40

5i-37

3*66

Moon I

23. 25. 5o'O2

So'oo

ri2-4.3i

23. 33. i8-38

18*28

3o* 64.

12-36

23. 42. ii • 82

1 1 * o5

I2'5l

23. 52. 40* 52

4.0*4.1

53-04

12-63

2 Ceti

23.57. 7-32

7-38

10* 81

12*^3

I. 2. 3l ' 62

3l * 20

4.3 *OI

59*5o

ii -08

I2'4.8

20'OOO E.

I. 12. 4.8* Id.

4.8*26

57-8a

0'56

20- too E.

flCeti

i. 17. 34- 1 6

34-16

[20-108]

December 14.

ios-o, 25'-o, 39"8, 55"
2i»-o, 35"2, 5o*-o, 4«

5, io"o. Before sunset.
8, i9"-o.

96

TRANSIT OF VENUS, 1874. HONOLULU.

Day.

Observer.

Reading and
Position of
Micrometer.
[Adopted
Reading for
Zero of
Collimation.]

Object observed
and
(Number of Wires).

Mean observed
Clock-Time of

Transit over the

i

Centre Wire.

Seconds
of True
Transit
over the
Meridian.

Seconds
of Stars
Assumed
Apparent
R. A.

Clock
apparently
Slow.

1874.
December i5

16

17
18

19

NO
K

K

NO

NI

NO

R

NI
H

T
NO

r
20- ioo E.

20- ioo E.
20-000 E.

20- ioo E.
? j

1 y

) »
J »
J >

20- ioo E.
19-462 E.
20- ioo E.
20- 573 E.

20 • i oo E.

• [20-108]

20- ioo E.

21-491 E.
20- ioo E.

2o'5oo E.
20- ioo E.
[20-108]
19-500 E.
20-100 E.
20-171 E.

20-262 E.
20-100 E.

j >

20-934 W.
[20- 109]

20- ioo W.
[20- 109]

h in ,

1.24. 35-46
6. o. 14-64
6. 12. 8-20

o. 12. 5o- 62
o. 16. 42-06
0.41. 58-98
o. 46. 24-40
o. 49. 36- 3i
o. 56. i4-58
i. 6. 59'3o
i. 38. 35-o8
6. 7. 8-5o
6. 12. 39-33
6. 3o. 17-84
6. 42. 14-25
i3. 12. 20-43

I. 2. 3l -O2

i. 8.37-74
i. 16. 46-57
i. 24. 34-82
i. 47. 3i • 36
6.42. 7-86
6. 53. 30-42

7.49. 35-20
8. 2. 0-68
i3. 12. 8-57

i. i3. 3o'oo
1.24. 34-34
i. 34.42-44
1.38.34-38
i. 47. 3o-88
i.52.3i-i6
2. 3. 7-34
2. 6. i-3o

2. 10. 3f82
2. 21. 17-62

i3. 14. 28-
2. 10. 3 1 -42

2. 21. 17-62

35-3o
14-52
9'o5

5o -74
42-11
5S-98
24-46
36-o5
,4-57
59 ' 3o

35-06

8-35
7-16
17-75
27-45
40-88

30-72
37-95
48-03
34-70
3 1 -20
27 • oo
3o'79

o-o5
0-99

43-o3
34-26
42-47
34-38
30-78

3l'I2

7-29

1-23

31-96

17-62

39-73

3i-34
17-45

S

47-70
26-88
19-36

3-i9

ii-57
36-96
48-66
27-26
11-97
47-68
20-77
19-31
3o- 17
39-52
55-02

43-89

56-25
47-69
44-19
39-69
43-81

10-40
13-90
54-28

55-52
47-68
55-64
47-66
44-18
44- 5o

14-48
45-25
31-09

53-57

45-25
3i • 10

12-40
12-36
io-3i

12-45
[12-58]
12-59

I2'5o

12-61
12-69

12-67
12-62
12-42

I2'l5

12-42
12-07

14-14

i3-i7
[i3-o4]

8-22

12-99
12-99

12-69

I 3 -02

ic-35
12-91
15-29

11-49

13-42
I3-I7
13-28
1 3 -40
13-38
[13-33]
13-25
13-29
13-47
i3-84

13-91
13-65

v Orionis

5 Ursie Minoris S.P

, Ceti

Moon I

S Pisciurn

20 Ceti

fji Andromedje (4)

e Piscium

^ Piscium ...-

o Piscium

77 Geminorum

S TJrsjc Miuoris S P

Polaris S P

/3 Andromeda^

Moon I .'

0 Arietis (3)

Polaris S P

BAG 609

Polaris S P (i)

67 Ceti (3)

|2 Ceti

December 16. )) i3s-o, 27" -5, 42s -o, 56" 7, ns-o.
17. }> 8* -7, 23"-o, 37"-6, 52s-5, 6s-8. Through cloud.
„ 18. D 37B-3,52s-3, 7"-4, 22«-6, 37s-o. Good observation

TABLE IV. — MERIDIONAL TRANSITS (continued).

97

Day.

Observer.

Heading and
Position of

Micrometer,
[Adopted
Reading for
Zero of
Collimation.]

Object observed
and
(Number of Wires).

Mean observed
Clock-Time of
Transit over the
Centre Wire.

Seconds
of True
Transit
over the
Meridian.

Seconds
of Stars
Assumed
Apparent
K. A.

Clock

apparently
Slow.

1874.

NO

v Ceti ... .

h m s
2. 20. 5 ' 54-

5-39

10" 18

I 3 ' 70

5 Ceti

2. 32. 5r -40

Sl'28

4-08

1 3 * 70

•>2 Ceti

2. 36. 35-96

35-82

49* 82

tr Arietis

22 '27

35-86

i3-5o

2. 5i. 5o' 72

4*36

1 3 ' QI

a Ceti •.

2. 55. 3i'56

3i "41

i3-8i

Moon I

3. i. 29-80

20 ' 54.

fi3-8ol

5 Arietis

3. 4. i5-86

i5-6o

20* 3o

I 3 ' 70

6. o. 12 • 84

12* 70

2O"OOO W.

5 Urg£c Minoris S.P

6. ii. 53-71

7 ' IO

io* o3

1 1 • o3

20 • i oo W .

6. 21 . 19*10

IQ'OI

33-20

IA'28

6. 3o. i6*36

i6*3o

3O"22

20 • ooo W.

Cephei 5 r

6. 41. 45 ' 29

20" o5

n*o3

2O

NO

20' IOO W.

3. 26. 4.8-74.

48*81

3-i8

I4.-37

3.33. 4-70

A.' 5o

I 8 * Q4.

5 Kridani

3.37. I-76

i-83

16-35

14.- 52

3. 3o. AO'4.6

49-36

3*QI

I4.-55

33 Tauri

3. 4.O. 25 '4.6

25-36

3o* 02

14-56

3. Si. 58*02

58-ic

ia-65

14-55

3y Tauri

3.57. 4-58

&J1 Tauri

4. i. 39- 18

39* 10

53-75

14-65

26*86

4. 12. 27 ' O2

26- 96

14-56

X1 Tauri

4. 14. 44' 92

4.4.* 81

5o-32

IA-SI

20 ' ioo W.

5 Ursa* Minoris S.P

6. 12. S'OO

7-80

iS* QI

20 • ioo W.

/3 Canis

6. 16. 57*80

57-o3

19* 671 W.

6.42. 7 -85

27 "42

21

T

[20-109]
20 ' ioo W.

Moon I (3)

5 ii z3 *oi

-•2*86

Pi^-sii

Moon II

5. i3. 56-iS

56*o3

fiS-nl

Cephei 5i

6.41. 32-55

£ Geminorura

6. 56. 27* 3o

-7-25

i5-32

5 1 Gcminorum

7. 5.57-16

57-i3

i5-32

28 Canis

7. 0. 20 ' 86

3o* 1 1

45-38

T? -1"

5 Geminornm

7. 12. 25 • IO

25-o3

15-28

i Canis 'Minoris

7. I 7. 4.7 ' 12

a-36

iS-23

18 Canis Minoris

i5-3i

7. 22. 35-86

35-87

If 17

i5- 3o

Cantor (4)

7 26. 23-37

23-23

38- 35

i5 - 12

25 Monocerotis (4) ... .

4.0-35

A' *tl

i5- 16

Procyon (4)

7 . 3 1 3 o - 'i i

46* 2 5

[20* 109!

December 19. j) I. 59"o, i4"-o, 29"-8, 455'7, o*-6. Limb unsteady ; raining.
„ 20. }i I. 55s- 1, 10"- 5, 27"-o, 43"2, 59*- 1.

„ 21. )) I. So"- 1, ,23"'o, , 56s-o. Overcast; limb very faint.

B II. 23"'o, 39'- 5, 56"- 1, i3"o, 29"4. Correction for defective illuuiiiiation,

98

TRANSIT OF VENUS, 1874. HONOLULU.

Day.

Observer.

Reading and
Position of
Micrometer.
[Adopted
Reading for
Zero of
Collimation.]

Object observed
and
(Number of Wires).

Mean observed
Clock-Time of
Transit over the
Centre Wire.

Seconds
of True
Transit
over the
Meridian.

Seconds
of Stars
Assumed
Apparent
R. A.

Clock
apparently
Slow.

1874.
December zi

T

r

20 • loo W.

Pollux

h m S

7 37. a5 * 76

25-64

S

S

i5-i8

21 '196 W.

A. Ursa? Minoris S .P

52-8i

7'3l

22

NO

2O'IOO W.

34. '84,

5o-6i

l5'77

0*4-3

Moon I

2' 80

fiS-Til

6 22 37-36

ri5-74.i

y Geminorum ("4)

14-56

3o* 27

l5-7I

T

20-993 W.

Polaris S.P

1 3. 24. 5o-83

35*54

5o* 60

i5-i5

23

NO

[20' 109]

2O- IOO E.

Procyon "

7. 3z. 29-72

29" 64

46-30

16-66

24

It

20*100 E.

& Canis Minoris

7.20. 5-86

5-86

23-i6

2Q* I 5

46-32

I Argus

4.5 ' 07

3-i6

19-000 E.

A Ill-see Minoris S.P

7. 5i. 12- oo

47-85

4-66

16-81

20- 100 E.

8. 1.56-68

56-Qi

I4'o5

£ Cancri

8. 9.27-66

27-66

44-88

a1 Cancri

8. i5. 55-98

55-94

i3- 10

8. 20. 55-72

55-63

12-88

8. 25. 20- 3o

2O"2I

37* So

8. 32. 25-90

25-8i

41 ' 70

59-i5

1-7-36

29

It

[20- 109]
20- 100 E.

20 Ceti

o. A6. 17-32

17- 32

36*84

[20-115]
2O'OOO E.

29-58

4-6 • 27

16* 60

NO

20* ioo E.

i] Geminorum

6. 7. i -08

0*08

2O' 05

20*000 E.

8 Ursse Minoris S P . .

58-26

l8*22

20-000 E.

Cephei Si

21-75

20- ioo E.

6 Canis

6.48. 3-78

3"QO

23-96

2O' 06

T

20- ioo E.

Moon II

12. 38. 28-90

29*00

T2O' 24.1

3 1 Comae (4)

12, 45. 16* 14

i6-o5

36-38

20-33

57*8o

€ Virginis

12.55. 36-48

36-5o

56*86

20-36

9 Virginis

i3 3. 7-72

7-8.1

28' ii

i3. 5. 3-34

3*53

23 • 72

1 5, r8. T 5* A.A

i5-5o

35-76

2O' IOO E.

Polaris S.P

l3. 12. 12* 21

23-82

3o

K

20- ioo E.

5. 56. i2-i5

32*32

20* IOO E.

6. o. 6-88

6-81

20' ioo E.

20-36

[20-116]

December 22. ]) I. 29"-8, 46"-!, 2Si9, ig'-g, 36'-o. Correction for defective illumination, —o" 12.

3) II. 4"-2, io!-8, 378*i, 54s-i, ios'7.

„ 24. J II. 53" 8, 98-8, 26»-o, 42"o, 57"8.

„ 29. J II. o'-o, I4S*2, 29s*o, 43S'4, 57s- 8. Limb very steady

TABLE IV. — MERIDIONAL TRANSITS (continued}.

99

Day.

Observer.

Reading and
Position of
Micrometer.
[Adopted
Heading for
Zero of
Colliroation.]

Object observed
and
(Number of Wires).

Mean observed
Clock-Time of
Transit over the
Center Wire.

Seconds
of True
Transit
over the
Meridian.

Seconds
of Stars
Assumed
Apparent
R. A.

Clock
apparently
Slow.

1874.
December 3o

K

r

20* 542 E.

Cephei 5i (i)

h m s

6. 4.1. 5o*

2O '22

S

4.1 ' 08

S

20* 100 E.

6. 5?. 46-84.

46*o3

7- 12. 2O1 28

20-18

20* 3 1

7. 2O. 3'O4

3-oi

23-26

7. 26. iS-z6

18-11

38-55

7 32 26' 08

4.6-4.3

XO

18-840 E.
[20*116]
20- 100 E.

\ Ursae Minoris S.P. (3)
3i Coraee (3)

7. 5i.43*oo
12.45. i5-83

41-21
1 5 " 74

0-92
36-42

19-71

•
20*68

5 Virginis

12. 48. 5y* 5o

57-52

i8-o3

12. 55. 36-12

36-io

56-8o

i3. 3. 7-48

7-54

28- 14.

21 • 004 E.

Polaris S.P

i3. 0.4.8-71

20-86

43-37

2O' IOO E.

i3. 18. 14*96

i5-o5

35-70

I 3. 22. I ' 22

i-3o

[20-651

3i

R

2O'OOO E,

I. 12. I4*OO

23 -3i

44-55

2O* IOO E.

e Ceti

I. 17. 25 * Q4.

25 '07

4.6*4.6

T

20 ' ioo E.

12. 41. 8*06

8-i5

3 1 Comae

12. 45. 1 5 '40

i5-34

36-45

8 Virginis

12. 4.8. 56*04.

57-o3

18-07

f Virginis

12. 55. 35-8z

35-88

56-93

2I'25o E.

Polans S.P

i3. 9. 7-28

16-45

42-55

26* 10

17-875 E

Polaris S.P. ...

i3. 18. 3-66

21 * Q4

42-55

20 • ioo E.

13.26. 1-28

I '47

22'3Q

2O*Q2

i3. 27. 57-85

57-o6

l8-82

2O*86

m Virginis

i3. 34.41-36

41-53

2-35

2Og82

T Bootis

13.40. 57-68

57-70

l8'77

21 '07

Moon II

14. 6. 35-96

36-17

[21 -oil

14. 9. 35-90

35-90

56*89

2O* 00

1875.
January i

NT

[20-117]

I. 12. 3? ' 06

30-78

NO

5 Ursae Minoris S P

6. ii. 58-86

57-32

i8'23

12*26

33-48

[20-118]
20 • 5oo E.

6. 4.1. 57*4-3

20- 64

4.2* I 3

21 '4.O

20* ioo E.

0 Can is '. , . .

6. 48. 2*44

2-67

23 * 00

21-32

T

18-912 E.

Polaris S.P

i3. 25.26-57

18-37

4.1 * 77

23*4.0

20* ioo E.

T Bootis (3)

1 3. 40. 57- 12

57-16

18-81

21*65

l3. 4.8. 21 ' 04.

21-08

4.3 '.11

21 '43

1 3. 54. 54-78

54.* Q2

i6-3o

21 -47

0 Centauri

i3. 58. 56-76

57-18

18-63

21 '4.5

[20*118]

December 3o.
Si.

3i'-8,46"-3, i*"4, i6"-o, 3o5- 5. After sum i-r.
6"o. 2o"'9, 36"-o, 5i*-o, 5"-8. Limb bright and steady ; an hour after sunrise.

0

100

TRANSIT OF VENUS, 1874. HONOLULU.

Day.

Observer.

Beading and
Position of
Micrometer.
[Adopted
Reading for
Zero of
Collimation.]

Object observed
and
(Number of Wires).

Mean observed
Clock-Time of
Transit over the
Center Wire.

Seconds
of True
Transit
over the
Meridian.

Seconds
of Stars
Assumed
Apparent
R. A.

Clock
apparently
Slow.

i875.
January i

2

•
6

9

T

K
T

K

T

R

T

r

20- ioo E.
f >
> >

» »
[ao-ixS]

20 • 100 E.

> »
19-750 E.
20* 5oo E.
20* 100 E.

2O' ICO E.

j •>
5 1

» j
» >

[10-119]

21-750 W.
20' i oo W.

22-II4W.

20 • 100 \V.

2O-OOO W.
2O- IOO W.
J >
» J
J J
> J
20'ICO W.

i9-?5oW.

[20-122]

20-120 W.
2O- I2O W.

20 • 144 W.

20-120 W.
) >
> )

> »

20-988 W.

20- J20 W.
[2O- J2l]

h m s
1A. 5.51-27
14. 9-35-52
14.26. 4'38
14.39. 9-34

14.43. 35-02
14. 53. 17-34

I. 12. 2V54

6. 6.59-54
6. 12. 14-83
6. 41. 58-40
6. 57.45-60
i3. 12. 3-76
1 3. 54. 54-32
14. 5. 50-64
14. 9. 34- 94
14. 39. 8-84
14.43.34-53

I. S. 8-29
6. 6. 56-22
6.21. 53-
6. 3o. 5 • 54
6.41. 34'5o
6. 47. 58-92
6.53. 18-78
6.56. j7-S8
6. 57.42-18
7- 5.47-74
i3. 3. 3-34
i3.ii. i-33

6. 3o. 2-64
6.37.49-59
6. 41. 19-70
6. 47. 56-04
6.53. 15-94
6.57. 39-34
7. 5.44-S4

7. 12. I2-72

7. 24. 38-20
7.32. 18-60
7.37.13-36

51-49

35-55
4-33
9-3i
35-27
17-62

19-97
59-56

57-93

21 "O6

45-S7
16-35

54'5i
50-90
35-02
8-96
34-83

18-41

56-09
52-40
5-45
18-04
59-02
18-98

I?1??
42-30
47-65
3-40
14-82

2-62
49-60
14-76
56-17
16-18
39'5o
44-82
12-67
27-65
18-64
i3-27

R

12-83
56-92
25-83
3o-85
56-74

42-97
20-99
18-22

42-22
7-28
40-98
16-42
12-86
56-95
3o-8S
56-77

39-66

21 -O2

i8-i5
30-47
42-67
24-03
44-04
42-83
7-32
12-71
28-37
37-60

30-49
i7-5i
42-87
24-05
44-06

7-34
12-74
40-64
55-8i
46-57
41-20

21-34
21-37
21 • 5o

21-54

21-47

[21-48]

23 'DO

21-43

20-29
21 • 16

21-41
24-63

21 -91

21 -96
2I-93
21-92
21-94

21-25
24-93

25-75
25" O2

24-63
25-01

25-06

25-o6
25-02
25-o6
24-97

22-78

27-87
27-91
28-11

27-88
27-88
27-^4
27-92
27-97
28-16
27-93
27-93

p I5o6tis

y Canis

Polaris S.P

f2 Bootis

a- Libra (&) . .

f S Ursa; Minoris S.P. on 5th ]

g Canis ,

7 Canis (3)

Polaris S.P. (3)

{A. Hi-see Minoris S.P. on "1
wire I J"

Pollux

January i. > 46'-6, 2"-o, I7s-o, 33'-o, 48"-o. Wire 4 has been increased i'.

TABLE IV. — MERIDIONAL TRANSITS (continued).

101

Day.

Observer.

Reading and
Position of
.Micrometer.
[Adopted
lieading for
Zero of
Collimation.]

Object observed
and
(Number of Wires).

Mean observed
Clock-Time of
Transit over the
Center Wire.

Seconds
of True
Transit
over the
Meridian.

Seconds
of Stars
Assumed
Apparent
R. A.

Clock
apparently
Slow.

1875.
Janaarv 9

R

20- i 20 W

0*5?

28' A-7

«

20-125 W.

Polaris S.P

i3 ii 55-83

7T3

34-63

ii

I

20- III W.

Polaris

8*27

19-753 w.

T] Piscium

i8*o5

u

20- ooo W.

4.8*36

l8'35

29 ^9

19 • 5oo W.

i3*6o

42-85

20* 1 20 AV.

& Canis

6.47 54-58

54/78

29 2

T

20*046 W.

Polaris S.P

i3. ii 38*8o

2* 84

32-6->

29 29

20' I2O W.

i3. 18. 6-22

6*38

36-21

29-83

12

B

[20-IlS]

20-000 \\'.

Polaris

I. 12. 33*71

2*68

33-7A

3 1 -06

12 55 26-86

S-r- ?•>'

3o* 62

58-10

^8 • ^T

ig-g58 \V.

Pohris S P

3l-67

3i • ?fi

20 - 1 20 W.

i1* 18 5-6o

5*78

36-24

•3-r-i- ..ft

48-62

I 3 34 32 ' 12

*"rf

i 3 38 3-86

li'TI

3o' 5 1

i 3 40 48*88

48* 8Q

3o* 3i

5*76

36- 34

3o-58

16-75

3o*5o

i3

T

[20*116]
20 ' 1 20 W.

48-23

o 52 33 * 10

33*O2

o 55 55-96

55*87

43 • 5o

20-125 W.

2'8l

32-go

0 Ceti

i5*3i

46-32

i6*36

3i*o6

K

28-61

20 • ooo W.

Polaris S.P

i3. 1 1. 27 - 12

53*o5

3o* 77

31-82

U

[20-115]

3 1 ' 9 5

i 29 56*36

56-32

28 * 10

31-78

r 3j. 2,3 * 6j.

23-62

55-39

3l '77

56-02

T3i -70!

e Cpti (A)

50-67

22- 5 I

31-84

v Ceti

18*96

31-67

S Ceti

2 32 32*86

32-87

'v" Ceti (a/) .

z 36 17*63

17-63

40 -63

3-98

35-66

3i-68

[20- i i 5]

January 1 3.
„ 14.

- , i8"-o, 33s-i, 48s-o, 2s-5.
26"6, 4i!-o, - , - , - .

Limb steady.
Linib steady.

Wire 2 bad. Before sunset.

o 2

102

TRANSIT OF VENUS, 1874. HONOLULU.

Day.

Observer.

Reading and
Position of
Micrometer.
[Adopted
Reading for
Zero of
Collimation.]

Object observed
and
(Number of Wires).

Mean observed
Clock-Time of
Transit over the
Center Wire.

Seconds
of True
Transit
over the

Meridian.

Seconds
of Stars
Assumed
Apparent
E, A.

Clock
apparently
Slow.

1875.

R

•y2 Ceti (&) . .

h ni 5

32'22

f32-4.il

47 Arietis (4)

2 5o 23-87

23-86

56-24

32*38

a Ceti (4)

45-o3

3z' CA

8 Arietis (3)

3 3 56-83

56-82

29 - 23

o Tauri

3 17 33-o6

33'o5

5-65

3-, -go

/ Tauri

3. 23 26'36

26-35

58-76

32-41

€ Eridani

3.25 30-76

30-76

3 *oi

32-25

71 Eridani

I2'5l

32-5i

3y Tauri

3 56 46 -4A

4.6- 43

18*93

32 • 5o

cc1 Tauri

53-67

32-5o

20' 125 "W.

Polaris S P

i3. 11. 52'33

56-47

32-65

Spica

1 3. 1 8 3-54

3-55

36-34

32 ' 7Q

16

K

[20- i i 5]

2O' I2O W.

3. 32.45-96

4.5 ' 7Q

l8'70

33-oo

3. 38. 31-04

3o-8?

F33- 14!

4-4* 3o

33-23

3. 5 1. 39*42

30' 27

12* 5o

33-23

37 Tauri

3. 56.45-86

l8'Q2

33-23

20-53

53*66

T3-i3

46- 5 1

33-22

8-26

41 '46

33-20

47'88

33-i8

2O* 12O W.

5 Ursse Minoris S.P. (2)

6. ii. 46-73

46-27

57-3o

18-85

3o*53

32-58
33-14

Cephei 5i (i)

6 4i 0*33

33-56

NI

Polaris S.P. (3)

i3. ii. 54*33

54' 70

28-33

33-54

[20-II4]

20 • 1 20 W.

i ii 54 * 3 2

53-77

20-53

35-76

Moon I. (i)

56-52

F33-571

5. 59 53 -68

53*6i

27' l6

33-55

33-66

21-554 W.

S Ursae Minoris S.P. (2)
7 Geminorum

6. 17. i8-5o

45-60
56-87

. 18-93

3o-53

33-33
33-66

6. ?7. AA.' OO

43-93

17-56

33-63

i9'5oo W.

6. 41. 58*6o

0*4.3

33-17

& Canis

6. 47. 5o'58

5o-54

33-55

,g

[20'Il3]

20 • i 20 E.

i. 1 1. 57* 60

55-70

28-70

33-oo

v Piscium

i. 34. 21 -46

21 * 24-

55-34

34-10

1 36 Tauri

55-ic

34'3i

F34-- iol

5. 55. 58-42

58-3o

32*41

34- 1 1

[20-111]

'Ti

January i5. ]> 44'

1 6. T> 59'

„ 17-3) —

., 18. D 46'

•4, 59" -5, 14" -7, 3o"o, 45' -i. Limb steady.
•6, i5"-o, 3i'-o, 478-o, 2s-7.

— , , 56"- 6, , , Overcast. S Ursae Minoris on Wire d.

•8, 3s-o, zo"o, 36"'7, 53s>o. Limb very steady.

TABLE IV. — MERIDIONAL TRANSITS (continued).

103

Day.

Observer.

Reading and
Position of
Micrometer.
[Adopted
Reading for
Zero of
Collimation.]

Object observed
and
(Number of Wires).

Mean observed
Clock-Time of
Transit over the
Center Wire.

Seconds
of True
Transit
over the
Meridian.

Seconds
of Stars
Assumed
Apparent
R. A.

Clock
apparently
Slow.

i875.
January 1 8

'9

20

B
T

T
B

i

20-120 E.
> )

19-500 E.
20-120 E.

» j
> >
2i-5oo E.

20-120 E.

11-873 E.

20-120 E.

- » >
> »
> )
> >

20-369 E.

20-120 E.
» »
> J
> J
J )
> >
» J

[20-111]
20-120 E.
19-983 E.
20- no E.

J )
) >
2I'23l E.
2O* IIO E.
» >
» y
) >
» >
J >
> )
> >
T >
J J

[20-111]

v Orionis

h m s

5.59.53-04

6. 6. 51-92
6. 12. 22-00
6.16.38-84
6. 20. 59-56
6. 29. 56-5o
6. 37.43-36
6.42. 58-oo

i. 34.20-78
i. 36. 35-5o
6. 6.47-36
6. ii. 44- 3o
6. 16. 38-20
6.20.58-88
6. 29. 55-90
6.37.42-72
6.41. 27-80
6.47.49-34.
6. 55. 10-42
7. 5.38-o6
7.12. 5-94
7.17.24-36

7- i9-48>74
7.47. 19-08

i. 2. 8-36
i. n. 25-66
6. 11.46-12

6.29.55-74
6. 37.42-54
6.42. 33- 5o
6.47.49-29
6.53. 9-20
6.57.32-54
7.12. 5-88
7. 17.23-99
7. 32. 11-62
7.37. 6-32
7.43.28-68
7. 59.34-60
8. 2. 1-84
8. 9.10-38

s

52-93

51-78
44-76

38-78
59-44
56-39
43-25
8-08

20-48
55-oJ
46-12

45-47
38-oo
58 -64
55-67
42-49
6-61
49-14
10-17
37-83
5-7o
24- n
48-53
23-19

8-ii
52-26

44'49
55-52
42-31

7'74
49-02
8-91
32-27
5-66

23-77
n-38
6-n
28-39
34-38
1-62
io-i5

B
27-l6

26"o3
19-00
12-87
33-5g
3o-54
17-57
42-59

55-33
27-82
21-07
19-07
12-87
33-59
3o-54
17-57
42-59
24-09

12-83
40-73
5g-i3
23-5o
53-54

43-39

26-88
19-15
3o-55
17-58
42-57
24-10
44-09
7-40
40-74
59" 10
46-69
41-34
3-5o

45-37

S

34-23
34-25
34-24
34-09
34- 15
34-15
34-32
34-5i

34-85
32-79

34-95
33-6o

34-87
34-95
34-87
35-o8
35-98
34-95
[34-97]
35-oo
35-o3
35-02
34-97
3o-35

35-28
34-62
34-66
35-o3
35-27
34-83
35-07
35-i8
35-i3
35-o8
35-33
35-3i
35-23
35-n
[35-20]
[35-zo]

35-22

8 Ursae Minoris S.P

3 Canis Majoris

| Geminortmi

v Piscium (4)

Polaris on 5th wire (4) . .

5 Ursse Miuoris S P

3 Canis Majoris

v Geminorum

7 Geminorum

| Geminorum

B Canis

8 Geminorum

3 Canis Minoris

A Ursae Minoris S.P ...

Polaris

4

8 tlrsffi Minoris S P

Cephei 5i d} . .

Pollux

£ Ar<*us

Moon I

Moon II

& Cancri (4)

January 19. 5 I. 37S'4, 53"'9, io"'4, 27«-o, 43"-3. Some tremor.
„ 20. }) I. 2"4, i8'-2, 34"6, 5i"o, 6"9. Some tremor.

]) II. 29s-5,45*-6, i!>9, i8"-i, 34"2. Correction for defective illumination, +o"O7.

104

TRANSIT OF VENUS, 1874. HONOLULU.

Day.

Observer.

Heading and

Position of
Micrometer.
[Adopted
Reading for
Zero of
Collimation-]

Object observed
and
(Number of Wires),

Mean observed
Clock Time of
Transit over the
Center Wire.

Seconds
of True
Transit
over the
Meridian.

Seconds
of Stars
Assumed
Apparent
E. A.

Clock
apparently
Slow.

1875.
January 21

T

i

20* no W.

Pollux

7 ^7 5 "l(i

?• "i1;

41 ' 35

1 C . Qn

20-798 W.

A. TJrsae Minoris S P

3 33

I7'"6

53-O-*

^ C . QT

22

T

[20-111]
20* 127 W.

A Ursae Minoris S.P

52-93

36-22

2O'IIO W.

6 Caucri

7 55 i5'8o

i5-6i

5i • 83

36-22

R

Moon II

nfi'ool

3 7 Leonis

59'25

36--'6

(ji Hydrac

27-63

Ti-no

p Leonis

10 z5 38-88

38-68

•" yy

36 -08

1 Leonis

5 Leonis

52-54

"8-59

36-o5

5 Crateris (2)

3o" o^

6-21

36- 19

v Leonis

$7'5l

33'6o

# Leonis

5-58

36- 19

23

B

[20*111]

iO'IIO W.

5 Ursa Minoris S.P

43-25

19-56

36-3i

7 Geminorum

54-26

3o-55

36-->9

iS'75o W.

Cephei 5i

5-89

36-45

20 • no \V.

e Canis Majoris

6 53 7Po6

7-65

36-43

NO

p Leonis

10 25 38-54

38-38

IA.' ?S

34 Sextantis . .

34-52

ii'iS

36-6i

/ Leonis

5-77

36-42

Moon II

2-80

r36-5il

10 53 3o-8o

3o-63

36-54

jo 5y 58'6o

58' A4.

35-04

36- 60

5 Leonis (4)

ii 6 52-37

28-61

36-37

S Crateris

29 • 63

36-6i

24

NO

[20-111]
2o'ooo W.

5 TJrsce Minoris S.P

6 ii 37*43

4.2' 84.

36-89

20* no \V.

6 29 53-86

53-67

3o-55

36-88

20*000 "W.

Cephei 5 1

5-3i

36-88

II

20 ' 1 10 \V.

56-8o

33-65

36-76

Moon II .

r36-8ol

26-84

36-89

£ Virginia (4)

ii i3 3i'8o

H* 70

ii-73

ii 53 5 1 • 94

5i-85

28'77

36-92

54-33

3l'I7

36-84

p Virginis

3A-o3

3? " OA

3 5 Virginis

53-14.

36-85

3 1 Coma?

0' A3

37-32

36-Sg

> >
[20' in]

Polaris S.P

1 3. 11.48-49

43-92

20-80

•j r , OO
JO 06

January 22. J) i2«-i, 27"- 1, 42"5, 58s-o, i25-8.
„ 23. )) 33»-6,48»-2, 3s-o, i8"-o, 32»-5.
„ 24. )) 32s-8, 47"-o, is'7, i6!>2, 3o5'9.

TABLE IV. — MERIDIONAL TRANSITS (continued).

105

Day.

Observer.

Heading and
Position of
Micrometer.
[Adopted
Reading for
Zero of
Collimation.]

Object observed
and
(Number of Wires).

Mean observed
Clock Time of
Transit over the
Center Wire.

Seconds Seconds
of True , of Stars
Transit ! Assumed
over the Apparent
Meridian. K. A.

Clock
apparently
Slow.

i875.
January 25

26
27

T

so

T
T

r

20- no TV.

) »
t >

5 »

» J
> >

) >
» >

20-094 TV.
20 • 1 1 o TV.

» »
[20- no]

i9-5ooTV.
20- no TV.
t j
t >
20- no E.
18-093 E.
20-110 E.
t »

3 1
) »

J t

[Z0-'l'll]

20- i 10 E.
20-000 E.
2o-5oo E.
20-110 E.
20-462 TV.
20- j 10 TV.
j »
> >
> »
> »
i >
> j
? >
* »

[20- in]

12. 12. 53-94
12. 18. 53-40
12. 3o. i5-38
12. 34. 56- 74
12. 40. 52-54
12. 44. 59-90
12.48. 41-54
12. 55. 20-42
i3. 2. 51-70
i3. 11.41-37
i3. 17. 59-44
13.27.42-34
13.42. 0-24

6.41. 52-8o
6.53. 6-62
6.56. 5-40
7. 5.35-20
i3. 2. 54-44
i3. 17. 2-91
i3. 27.41-96
1 3. 34. 25-6o
13.43. 59-10
13.48. 6-44
i3. 54. 39-46
14. 4. 35-92
14. 9.20-14

6. 6-43-32
6. 11. 49-80
6.41. 35-8o
6.47.46-34
i3. 12. 34-67
i3. 17. 58-64
i3. 27. 41 -62
1 3. 34.2.5-14
i3. 37. 57-10
1 3. 40. 41 -66
13.43.58-64
13.47. 16-22
i3. 51.59-98
14. 5.35-4S
14. 9.19-64

53-8o
53-26
15-19
56-6i
52-40

41-40
20-29
5i-56
42-40
59-30
42-20
o-i3

6-27
6-43
5-27
35-o6
54-25
41-69

4' "77
2.5-41
58-90
6-26
39-27

35-74
19-96

43-i3
43-19
4-61
46-17
40-95
58-56
41-53
25 -06
57-04
41-55
58-58
16- 14

35-40
19-53

3l'20

52-62

34-06

30'02

37-35
18-89
57-76
28-99
19-87

ig-65

41-86
44-07
42-96
12-85

19-42
19-68

3-22

36-86

44-27
17-22
13-67
57-76

2i-o5

2O'3l

41-68
24-09
18-14
36-73
19-71
3-26
35-21
19-69
36-90

38-io
13-71

57-79

37-40
[37-45]
37-43

37-57

37-49

37-47

37-43

37-47
37-3i
37-45
37-56

35-59
37-64
37-69
37-79
[37-89]
37-73
37-91
37-81
37-96
38-ci
37-95
37-93
37-80

37-92
37-12

37-92
37-19
38-i7
38-i8
38-20
38-17
38-14
38-32

[38-22]

38-23
38-3i
38-26

.Moon II

T Centauri

p Virginis

Polaris S P ...

£ Geniinorum

5 1 Geniinorum

Moon II

Polaris S.P

S Ursa; Minoris S.P

6 Canis Majoris

Polaiis S.P

/c1 Centauri

Moon 11

Piazzi XIII. 264

K Virginis

Arcturus

January 25. )> 24"- 5, 38s- 8, 53<'4, 8s -o, 22' -4.
„ 26. )) 25*-3, 59"8, 54t-5, 9"-2, 23s-3. Overcast ; rain.

106

TRANSIT OF VENUS, 1874. HONOLULU.

Day.

Observer.

Reading and
Position of
Micrometer.
[Adopted
Reading for
Zero of
Collimation.]

Object observed
and
(Number of Wires).

Mean observed
Clock Time of
Transit over the
Center Wire.

Seconds
of True
Transit
over the
Meridian.

Seconds
of Stars
Assumed
Apparent
R. A.

Clock
apparently
Slow.

1875.
January 28

29
3o

NO
T

1C

T

NO
T

r

16-896 E.
20-110 E.
21-000 E.

2O- IIO E.
20-110 W.
1 i
J >

J »
J )

» >
) )
> »

» J

[20-111]

20-110 W.

20-000 W.
ig-Soo W.

20'HO W.

J J
) >

J )
» »
» >

> J

» »

[20-111]

20-110 E.
20 • ooo E.
20 • ooo E.
20-110 E.

) J
> >
1 1
) 1
> >
J )
) >
> )
» »
> )
*J t

[20-111]

h m s

6. i5. 4-50
6. 20. 55-o6
6.42. 16-86
6.47.45-64
14. 5.35-o6
14. 9. 19-24
14. 19. 59-92
14. 25.48-08

14.33. 6-12

14.38.53-08

14. 49. 20-20
14. 58. 26-5i
1 5. 4. 26-80

6. 6.42-28
6. ii. 35-8o
6. 41. 5o" 60
6.47.45-18
14.43. 18-44
14. 49. 19-86
1 5. 4. 26-24
i5. 9. 37-40
i5. 21. 23-06
i5. 28.44-34
i5. 37.27-16

6. 6. 41 • 60
6. ii. 44-60
6.40. 57-80
6.47.44-44
i5. 9.36-80
i5. i5. 23-42
i5. 20. 32-38
15.28.43-92
15.37.26-68
15.43.54-94
i5. 5o. 0-74
i5. 57. 29-64
16. 7. 7-46
16. 12. 5i-i8
16. 21. 4-02

42-31
54-91
5-82

45-54
34-98
19-11
59-79
47-95
6-06
52-93
20- 13
26-36
26-75

42-14
43 -o3
2-5o
45 -o5
18-38
19-80
26-18
37-34

23-01

44-25
27-08

41-54
40-45

2-90

44-48

36-83

23-47
32-43
43-78
26-64
54-91
0-66
29-71
7-46
5i -27
4'i3

2O'5o

33-58
4i-5i
24-09
13-74
57-83
38-75
26-79

3i-78
58-97
5-34
5-49

21 -o5
20-69

41-35
24-09

57-69

59-07

5-59
16-54

23-5i
6-3i

21-04
20-86

41 -21
24-09

16-58
3-i8

12' l6

23-55
6-34
34-73
40-42
9-60
47' '4

43-90

38-i9
38-67
35-69
38-55
38-76
38-72
38-96
38 -84

[38-78]
38-85
38 -84
38-98
38-74

38-91
37-66
38-85
39-04
39-31
39-27
39-41
39-20

[39'*8]
39-26
39-23

39-5o
40-41
38-3i
39-61
39-75
39-71
39-73
39-77
39-70
39-82
39-76
39-89
39-68
[39-76]
39-77

/- Bootis

f- Bootis

i|/ Bootis (4)

5 UrssE Minoris S P

S Canis

|2 Libra;

$ Libra

a Serpentis

5 Ursae Minoris S P

6 Canis

18 Librae

o2 Librae (4)

C1 Libra

/31 Seorpii

S Ophiuchi

Moon 11

January 28. 5 36"o, 5os'7, 6«- 1, 2i"-5, 368-4.

„ 29. J> 52»-o, 7s-2, 238-o, 38"9, 54"-3. After sunrise. Limb steady and bright.

„ 3o. j) I9"o, 35s-o, 5i"2, 7S'4, 238-2. An hour after sunrise. Limb steady and bright.

TABLE IV. — MERIDIONAL TRANSITS (concluded).

107

Day.

Observer.

Heading and
Position of
Micrometer.
[Adopted
Reading for
Zero of
Collimation.]

Object observed
and
(Number of Wires).

Mean observed
Clock Time of
Transit over the
Center Wire.

Seconds
of True
Transit
over the
Meridian.

Seconds
of Stars
Assumed
Apparent
E. A.

Clock
apparently
Slow.

1875.

i

h m s

6.12. 3-33

41-55

I
21 'O3

a
3o-A8

20* i 10 E.

6. 16. 33*oo

32* 97

I2'8l

30-84.

6.41. 53-33

2'l3

AI *O7

38-04

20 ' no E.

6. 47. Ad * 2O

A A* | $

2A*OQ

3q- 04

e Canis Majoris

4-18

AA ' o5

3Q-87

27-56

?-3<j

39'83

7 5 32'08

32' GO

12-86

45 -q5

[20-111]
2o-5oo W

5 Ursffi Minoris S P

6 12 6*80

22* I 8

33-54

43* 1 3

3o-5o

19-500 W

57-78

42*33

[20-110]

21-017 W.

4 58 53-83

3-47

Rirrel

32-56

iV 1i

j8 Tauri

24.- 35

4.3-73

83-O4.

43 * 80

6 ii Sj-SS

3? • ID

22' 43

56-72

39-86

20-858 W.

0*53

54-83

45*3o

2o'75o W.

Polaris S P

i3 12 58'2o

8-?3

g

[20- no]

3.5i 28'2O

4. 5 2-28

46-23

e UrssB Minoris S.P

4 58 2*32

3 -20

5 Ursai Minoris S.P

3o-35

43.35

22-688 W

A UrssB Minoris S.P. . . .

10-85

55-23

A A • 38

10-667 W

Polaris SP

7-86

45-62

[20'IIO]

20 • no W.

i-38

7 Tauri

4. ii 56-58

56-35

44-85

5 Ursse Minoris S.P

37 * Q2

23 *OO

45-08

53-4I

38*oo

45*57

18-600 W.
20-287 W.

X Ursae Minoris &.P. (4)
Polaris S.P

7.42. 2-88

I4-49
23-28

55-71

41-22

4.3-78

20-321 W.

21 ' 34

6-67

4.5-33

35 -o5

4.5-3i

[20-110]

January 3i. }) II. i3" i, 29"-2, 46"o, 2"8, i9a-o. Two hours after sunrise. Tremor.

108

TRANSIT OF VENUS, 1874. HONOLULU.

TABLE V. — EKROHS and RATES of the TRANSIT-CLOCK.

J»74-

Observer.

Number of
Clock Stars
observed.

Sidereal Time.

1
Clock Slow,

corrected for
Personal Equation.

Clock's Loss in
24''. Sidereal.

Adopted
Losing Rate.

h m

_

B

,

October 3

T

9

20.55

+ 4'36

,

. .

+ ii-5z

NO

4

i. 14

6-17

J

4

R

4

1.27

17-89

+ 11-52 11-25

5

K
NO

8
4

20. 3g
o.55

26-79
28-60

10-98

II'OO

6

T

10

20. 5 I

1'47

r85

B

5

2. 2O

i-93

i

7

NI
It

9
8

21. 5
23.26

3-39
3-6z

1-90

1-90

8

T

5

22. 52

5-40

]

It

5

2.26

5-76 1-89

1-91

NO

i

5.42

6-45

J

9

NO

5

23. 9

7'49

1

T

5

1.46

7-56

1-94

1-88

It

2

7- 3

7-95

J

ii

NI

7

o. 3o

II'IO

} 1-81

1-60

it

2

7- 2

11-71

J

H

T

8

o. 40

iS-Sg

1-40

1-76

i5

NO

T

8

7

o. 14
6. Si

17-41
18-11

2-12

1-67

16

It

3

1.44

18-89

I'22

''74

"7

T

8

20. 9

20-84

1

NO

8

0.28

20-54

2-26

2-29

It

7

6.32

21-90

J

18

T
T

3
6

20. 10
2.29

22-98

23-52

2-32

1-96

'9

NO

8

22. 3

24-76

i-59

1-80

20

R

3

22.48

26-92

NO

i

r.Jj

26-92

2'O2

1-94

21

T

7

22. 3 I

28-61

NO

4

6.37

29-38

I r85

1-79

22

NO

6

23.39

3 0-44

1

T

5

1.49

30-74

,73

1-76

K

2

6. i5

30-96

J

23

T

7

o.36

32-36

1-79

1-79

24

NO
It

4

2

o.55
6. 5i

34-17
34-66

I 1-80

1-81

25

NO
It

3
3

1.25
2. II

35-90
36-26

I r83

1-88

26

NO
It

9
6

3. i5
6.46

38-io

+ 38-46

+ 1-94

+ 1-81

TABLE V. — ERRORS AND RATES OF THE TRANSIT-CLOCK (continued).

109

i874.

Observer.

Number of
Clock Stars
observed.

Sidereal Time.

Clock Slow,
corrected for
Personal Equation.

Clock's Loss in
24h. Sidereal.

Adopted
Losing Kate.

h ill

,

October 27

u 7
xo 6

2. 9
5. ii

+ 39-77
39-96

+ 1-68

+ 2-OO

28

xo

i

o.56

41-91

2-32

,95

29

R

6

2. 2

43-56

,58

1-89

3o

T

7

2. I 3

45-77

2'2O

2-18

November 2

T

2

o. 4

5z-o8

2- 1 6

2-16

3
4

T
XO

B

5
8

4

2O. 12
O. 22

6.38

53-93

+ 54-25

1

+ 2-17

— 25-72

5

II
XO

2

7

1.28
6. 5i

-3o-68 T
-3,6i

- 5-94

6

7

XO

R

U

so

8

7

4

2

o. 3i
7. i5

i. 18
6. Si

-37^ 1 -^

- 5-9,

+ 2-78
2-80

} -

- 0-18

8

T
K

2 1.37

6 7. ii

2-54
2-63

| - 0-18

— 0-20

9

it 8
xo 3

i. 38
6.47

2-38

2'45

> — O"22

— 0-07

10

-NO

8

'• 7

2-46

+ 0-07

— o-o 3

ii

K

7

I. ZZ

2-32

- 0-14

+ O'lO

12

T
H

6
8

1.42
7-43

2-7I
2-72

I + o-35

0-45

i3

XO
T

8

7

o. 34

7- 19

3-i5
3-35

} o-55

0-43

'4

XO
R

8
6

o. 3o

7- 4

3-5o
3-65

0-32

o-3 1

i5

XO

R

8
6

21. 2O
I. 52

3-82
3-8i

o-3o

o-35

it

T
R

8

2

22.27
2.44

4-20
4-33

0-41

0-40

„ I?

XO

5

o. 37

4-65

0-40

0-40

22

T

ii

2. 17

4'97

XO

9

6.44

5-io

J

0-40

23

xo

9 I. 22

5-36

]

T

8 4.46

5-49

o-43

0-40

U

7 7-21

5-52

J

24

T

i i. 33

5-78

o-37

0-32

25

T

i i3. 19

6-18

0-27

o-36

26

XO

10 o. 55

+ 6-40

+ 0-46 +o-5o

Four days heavy rain.

p 2

110

TRANSIT OF VENUS, 1874. HONOLULU.

i874.

Observer.

Number of
Clock Stars
observed.

Sidereal Time.

Clock Slow,
corrected for
Personal Equation.

Clock's Loss in
24''. Sidereal.

Adopted
Losing Rate.

JTovember 27

NO

9

h m

i.ig

s

+ 6-91

i

i

R

7

7. 12

7-11

+ o-53

+ 0-44

T

7

9.33

7'i3

\

28

T

5

2.19

7-41

}

NO

2

7.29

7-5o

V o-35

o-3 1

R

5

9.52

7-34

\

29

R

T

8

5

2. 0

10. 29

7-60

7-71

0-26

o-25

3o

NO
R

i

3

I. 18

6.47

7-87

o-23

O"22

December i

T
NO

7
9

2. O
6.44

8-04
8-i3

L 0-20

0*26

2

R

IO

6.58

8-44

o-33

o-34

3

T

8

I. 2

8-69

1

NO

5

5.32

8-77

} o-34

0-24

4

NO
R

g

IO

I. ft

6.36

8-77
9-00

o-i5

o-3o

5

R
NO

5
7

1.24
6. 38

9-28
9-41

0-46

o-53

6

T

7

I. 21

9-89

o'6i

0-48

7

R

NO

8
9

1.34

5.27

IO-22

10-33

o-35

o-3g

g

NO

T

9

g

o.58
7-49

10-67

10-72

0-41

o-3o

0

NO

8

i. i

10-86

-

y

0-18

0-25

R

g

6.43

10-88

IO

R

3

i. 8

11-07

,

y o-33

O-22

NO

9

5.27

11-26

II

NO
R

8
8

I. 14
5. 3i

n-3o

11-32

o-ii

O'2I

12

R

6

0.49

11-59

o-3 1

o-33

13

T

9

2. l5

I2'03

o-36

0-26

R

8

5.4i

11-98

«4

R

3

23. 7

11-99

]

R

6

i.34

I2'l5

0-16

0-26

NO

i

5. 18

12-43

\

i5

NO
R

12

8

o. 4
6.34

12-44

12-63

o-36

o-25

16

R

NO

7

10

o. 53
5.48

12-75
12-59

0-14

0'2g

17

NO
R

3
8

1.25

7. i3

i3-o5
i3-i8

0-42

0-46

18

R

g

1.52

13-55

0-49

0*42

'9

NO
NO

9
3

2.39
6.17

i3-83
+ 14-16

| + o-36

+ o-5 1

TABLE V. — ERRORS AND RATES OF THE TRANSIT-CLOCK (continued).

Ill

1 874.

Observer.

Number of
Clock Stare
observed.

Sidereal Time.

Clock Slow,
corrected for
Personal Equation.

Clock's Loss in
24h. Sidereal.

Adopted
Losing Rate.

It m

8

3

s

December 20

NO

10

3. So

+ 14-55

+ 0-66

+ 0-6 1

21

T

ii

7- 19

i5-25

o-56

o-56

22

NO

3

6. o

i5-77

o-55

0-71

23

NO

i

7.33

16-70

0-87

0-80

24

R

9

8. 6

17-45

o-73

0-68

26

R

6

8. 6

18-69

0-62

0-76

27

NO

9

5-47

ig-Si

0-91

o-73

29

R

4

0.44

19-80

]

NO

8

6. 20

20-12

}• o-55

o'5o

T

6

1 3. o

20-25

J

*

3o

R

10

7. 6

20-53

T

NO

7

12.53

20-68

0-46

o-38

3i

R

T

8
9

I. 0

i3.i7

20-72
20-99

o-3o

0-39

4

1875.

January i

NO

T

9
9

6.38
14. 10

21-32
21-47

} 0-48

0-44

2

R

8

6.36

21-68

T

5

14. 19

21-93

o-39

0-44

3

R

4

13.45

22-34

0-48 .

0-70

4

T

6

3-47

22-85

-,

R

8

12. 52

23-28

0-93

I'OO

5

R

8

6.36

24-05

1-07

1-02

6

T
R

8

7

6.48
i3. o

25-02
25-29

} 0-98

0-98

7

T
T

i

8

o.56
i3. 36

25-64
26-35

0-99

0-98

8

R

T

9

8

4.28
13.47

26-94
27-27

0-98

O-95

9

T
R

9
9

7- 2
i3. 9

27-90
28-21

0-92

0-88

10

R
T

8
ii

6.56

13.49

28-78
29-04

0-84

0-8 1

ii

T

4

i. 8

29-32

1

R

7

6. 3i

29-48

\. 0-78

0-84

T

8

i3.3g

29-93

J

12

R

12

13.36

3o-73

0-90

0-82

i3

T

6

i. 6

3 1 -04

-

I 0-7$

0-86

R

ii

13.27

Jrli

14

R

7

2.14

32-o3

0-96

0-79

i5

R
R

10

6

3. zi
iJ.39

32-65
32-99

| 0-62

0-66

16

R

9

4.27

33-39

0-69

0-55

'7

R

5

6.25

+ 33-83

+ 0-41

+ 0-48

112

TRANSIT OF VENUS, 1874. HONOLULU.

Number of

Clock Slow,

1875.

Observer.

Clock Stars

Sidereal Time.

corrected for

Clock's Loss in

Adopted

observed.

Personal Equation.

24''. Sidereal.

Losing Hate.

h in

s

January 18

HI

R

i
8

i.35

6. 12

+ 34-10
34-42

+ 0-54

+ o'6o

19

T
T

S

10

i. 28
6.46

34-82 -,

> o-65

o-55

20

T

i

i. 3

35-28 T

R

ii

y.iS

35-40

j- o-45

0-43

21

T

10

8.42

35-83

0-41

0-42

22

T
R

I

8

7.56
10. 53

36-22

36-33

0-44

o-37

23

11
NO

7
7

6.57
10. 5i

36-6o
* 36-55

o-3o

o-38

24

NO
R

i

10

6. 3i

12. 7

36-92
37-12

0-46

0-42

25

T

ii

12.55

37-47

o-37

0*40

26

NO

8

6.36

37-78

T

8

i3. 5o

37-91

0-42

o-36

27

B

T

8
9

6.27
13.44

38-o6

38-22

o-3o

0-46

28

NO

T

9
8

6.52
14.34

38-68
38-84

0-61

0-54

29

R

T

8
6

6.27
IS. 9

39-15
39-28

0-46

0-46

3o

NO

8

6. 24

39-58

1

T

10

1 5. 42

39-76

0-45

0-49

3i

R

8

6. 42

40-10

c-53

o-5o

February i

R

8

6.27

40-57

o-4i!

0-52

2

NO

8

7.36

41-14

o-55

o-58

3

NO

9

7-4

41-75

0-62

o-53

6

NO

2

6.26

43-07

0-44

0-54

7

NO

3

5.i8

43-67

o-63

0-62

8

T

2

3.59

44-24

0-60

0-68

9

R

2

4- 9

45-06

-.

T

2

1 5. 41

+ 45-32

> + 0-76

+ 0-76

1

TABLE VI. — ERRORS AND RATES OF THE ALTAZIMUTH-CLOCK.

113

TABLE VI. — COMPARISONS of the ALTAZIMUTH-CLOCK at HONOLULU with the TRANSIT-CLOCK by the

Intervention of a MEAN-TIME HALF-SECONDS CHRONOMETER and Inferred ERRORS and RATES of the

ALTAZIMUTH-CLOCK.

Day.

Observer.

Time by
Transit-Clock
at Comparison
with
Chronometer.

Time by Chronometer at
Comparison with

Time by
Altazimuth -
Clock at Com-
parison with
Chronometer.

Altazimuth-
Clock slow
on Apua
Sidereal Time.

Hourly Rate
of Altazimuth-
Clock.

Transit-Clock.

Altazimuth-
Clock.

1874.

h in s

)l U! s

h m s

h m s

,

s

October 2

NI

2o.53.35

8. 9.40-5

8.21. 5-o

21. 6.40

+ 33-63

+ 3-14

o. 46. 9

12. 1.40-5

12. ii. 35-5

o. 57. 37

+ 45-77.

3

NI

20. 3l. I

7.41. 6-0

7.45. o"5

20. 35. 54

-53-82

+ 1-52

23. 10. 1 5

10. 19. 55-o

10. ii. 3o"o

23. 2.44

— 50-07

T

5. 2. i5

4. 1 1 . o • o

4. 1 3. 40-5

5. 5.45

-40-94

+ 1-54

6. 34. 54

5.43.24-5

5. 39.40-5

6.31.57

-38-74

4

NI

5. 19.44

4.24.40-5

4. 3o. 22 -O

5.25.5o

- 3-82

6.33. 35

5. 38. 20-0

5.34-55-0

6. 3o. 32

- 2-23

+ 1-47

5

T

21. 21. 24

8. 23. 5o-o

8.26. 35-o

21. 24. 1 6

+ 20-48

23. 17. 10

10. 19. 18-0

10. i5. 8-0

23. i3. 4

23-23

+ i-5i

NI

4. 27. 56

3.29. i5-5

3.45.55-0

4- 44- 37

3i-53

6. 23. 24

5.24.25-5

5. 19. i5-o

6. 18. 10

33-82

+ 1-47

1

6

NI

20. 55. 20

7. 53. 29-0

8. 12.40-0

21. i3.57

38-65

+ i-5o

23. 5. 4

IO. 2. 52 -O

9.57.25-5

22. 58. 5y

41-27

7

T

5.58. 14

4. 5 1 . i • 5

4-56. 4-5

6. ,.S4

87-94

7- 9-4°

6. 2. 16-0

5. 57.47-0

7- 3.45

89-46

+ 1-47

1 5

T

21. 39. 8

8. 2. o-5

9. 4. i5-5

22.41. ig

32-65

22. 46. 40

9. 9.21-5

9. 7.15-0

22.44.18

32-57

+ o- 16

16

NI

22. 42. 39

9. 1.25-5

9. 6.40-5

22. 47. 37

36-53

o.35. 17

10. 53.45-0

10.48. io-o

o. 29. 23

36-89

+ O'2I

17

NI

23.36. 8

9. 5o. 5o-o

9. 56. lo-o

23.41. 8

41-82

o. 52. 56

ii. 7.25-5

ii. 4. 25-0

o. 49. 34

42-08

+ o-23

18

T

o. 32.47

io.43.25-5

io.58.35-o

0.47. 35

47-33

i.53. i5

o. 3.40-5

o. i. 5-o

i. 5o. i5

47-53

+ 0-20

'9

XI

23. 22.44

9. 27.40-0

9. 34. 55-o

23.27.33

5i-72

I. 22. 59

11.29. 35-5

11.24. °'5

i. 16. 56

52-09

+ 0-21

21

NI

22. 56. 33

8. 55.45-5

8.58.55-0

22. 59. IO

6i-73

23. 42. 5o

9. 41. 55"o

9. 36.25-0

23. 36. 46

61-86

+ O-2I

NI

1 . 24. I 2

11.23. o-5

11.28. o-o

I. 28. 39

62-01

+ O-O7

3.46. 5

i. 44. 3o-5

i.38.35-o

3.39.35

+ 62-60

+ O-27

October 3, noon. Altazimuth-Clock stopped to adjust pendulum.
October 6. Altazimuth-Clock, having run down, was wound and set going at 8h mean time. October 8. Pendulum adjusted.

114

TRANSIT OF VENUS, 1874. HONOLULU.

Day.

Observer.

Time by
Transit-Clock
at Comparison
with
Chronometer.

Time by Chronometer at
Comparison with

Time by
Altazimuth -
Clock at Com-
parison with
Chronometer.

Altazimuth-
Clock slow-
on Apua
Sidereal Time.

Hourly Rate
of Altazimuth-
Clock.

Transit-Clock.

Altazimuth-
Clock.

1874.

h „. ,

h m s

h a, t

h in s

s

,

October 22

NI

3.2i. 5

I. lS-40-0

1.20.35-5

3.25. 25

+ 67-08

+ o- 19

6. i. ii

3.55.20-0

3. 46. 40- o

5.51.53

67-54

23

T

2. 53. 3o

0.44. 14-5

0.47.43-0

2. 56. 20

71-60

o- 17

4. 29. 10

2. 19. 3g-0

2. I4.45-O

4. 23. 36

71-84

24

NI

3.52.15

i. 38.55-5

I.44.45-5

3.57.24

76-36

O-22

5. 40. 2

3.26.25-0

3. 21. 2O'O

5. 34. 14

76-71

25

T

5. o. So

2.43.25-5

2.48. 36-5

5. 5.i7

ll-ll

O'2O

7- 7-37

4.49.52-0

4.47.20-5

7. 4. 20

8i-S8

it

T

o.32. 55

IO. 12. 2O'O

10. 17. i"5

o. 36. 5o

85-22

o- 16

2. 27. 10

12. 6.16-5

n. Sg. 35-o

2. 19-40

85-49

NI

5.29.53

3. 8.3o-o

3. i3. 5-o

5.33.41

86-08

7. 23. 57

5. 2. iS-S

4.58. 55-o

7- I9-48

86-41

27

T

1.44-25

ii. 19. 44-5

II. 22. Sg-O

I. 46. So

89-73

O'2I

2. 46. IO

0. 21. ig-5

o. 16. 5-5

2. 40. 5

89-92

NI

5.35.48

3. 10. 3o-o

3. 16. io-5

5. 40. 39

90-45

O'2O

8. 19. 3o

5.53.45-5

5.48.50-0

8. 13.43

90-94

28

NI

2. 2O.45

11.52. 5-o

ii. 58. o-o

2. 25. 48

94-69

4. 27. 21

1.58.20-5

1.53.20-5

4. 21. 27

95-07

o- 19

29

NI

3. 3i. i5

0.58.30-5

i . 4. o-5

3. 35. So

99-58

o- 18

6. 12. 26

3.39. i5-5

3.34. o-5

6. 6. 14

ioo-o3

November 3

T

23. 7. 3o

8. iS. 12-0

8.20.45-5

23. 12. 0

118-61

o-iS

o. 46. 38

9.54. 3-5

9. 42. 12- O

o. 33. 40

118-80

4

T

8. 1.45

5. 2.34-0

5. 15.14-5

8.11.57

i24-58

+ o- 17

9. Si. 3o

6. 52. o-o

6.45. 16-5

9. 42. 14

+ 124-83

5

NI

8. 3.41

5. 0.20-0

5. 4-30-5

8. 7.25

- 4'83

— O' OI

9. i3. 18

6. 9.45-0

6. 6.45-0

9. 9. So

- 4-84

6

NI

23. 42. 49

8.36.45-0

8.41.55-0

23.47.28

— 4-02

+ o-o3

2. 35. 5g

ii. 29. 25-o

11.24. 35-5

2. 3o. 36

- 3-94

9

NI

o. 7.45

8. So. 5-o

8. 56. 10-0

o. 1 3. 54

- o-56

+ 0-04

2. 9. 16

io.5i.i5-5

10.46. 5-5

2. 4. 8

- 0-48

IO

NI

23. 23. I

8. 1.25-5

8. 6. 5-o

23.27.43

+ 0-75

+ 0-06

o. Si. 5o

9.29.59-5

9.26.15-5

0.48. 7

o-83

ii

NI

o. 3. 3o

8.37.45-0

8.43.20-5

o. 9. 7

''77

+ o-oS

2. 8. 6

10.42. o'o

10. 36. 20- S

2. 2. 26

+ 1-86

November 5, noon. Adjusted pendulum of Altazimuth-Clock.

TABLE VI. — ERRORS AND RATES OF THE ALTAZIMUTH-CLOCK (continued). 115

Day.

Observer.

Time by
Transit-Clock
at Comparison
with
Chronometer.

Time by Chronometer at
Comparison with

Time by
Altazimuth-
Clock at Com-
parison with
Chronometer.

Altazimuth -
Clock slow
on Apua
Sidereal Time.

Hourly Rate
of Altazimuth-
Clock.

Transit-Clock.

Altazimuth-
Clock.

1874.
November 1 2

NI

h in it
O. O. 2
2. 8. 13

h 111 s

8. 3o. i5-5
10.38. 5-o

h m a

8.33. io-5
10. 35.35-0

h m <
0. 2. 57

2. 5. 42

8

+ 3-i3

3-25

+ 0-06

i3

NI

o. 1.58

1.55.27

8. 28. 10-0

IO. 21. 2O -O

8. 33.20-0
10. 17.40-5

o. 7. 8
i. 51.46

4'o5
4-09

o-oz

'4

NI

0. 4, 25

i. 36.21

8.26. 35-o
9.58. i5-5

8.3i.2o-5
9. 5 1. 40-0

o. 9. 10

1.29.43

4-82
4-92

0-07

i5

NI

0.35.22

2. 1 6. 24

8.53.25-0
10. 34. 10-0

8.58.55-0
io.25.25-5

0.40. 5 1
2. 7. 36

5-75
5-89

O'lO

16

NI

I. 27. 7
3. 29. 28

9.41. o-o
11.43. o-5

9-44- 55-5
u.38. i5-5

3. 24. 40

6-41
6-5o

o-o5

.a

NI

22. 32. 24

6.42.45-0

6.53.46-5

22.43. 25

6-98

o-o3

22

NI

3.40. 3
5. 56.21

ii. 29. i5'5
i. 45. io-5

ii. 38. 40-0
1.40. 20-5

3.49.23
5.51.24

II' 12
11-23

o-oo

23

NI

3. 48. 26
7- 5.59

n. 33. 35-o
2.5o.35-o

u.38. 5-o
2.46. 3o-5

3. 52. 5o
7- J-47

I2'2I
I2'3l

o-o3

26

NI

4. 25. 27
5. 40. 14

ii. 58. 25-5
i. i3. o-o

12. 3. 5o-o
i. 9.25-0

4. 3o. 42
5/36.28

16-88
16-90

O'O2

27

NI

4. 45. 26

7. 5.55

12. 14. 2O'0
2.34.25-5

12. 18. 3o-5
2.26.55-0

4.49.26
6.58. 12

I8-24

i8-3i

o-o3

28

NI

4.13.48
6. 3. 56

n.38.45-5
1.28.35-0

n.45. i5-5
i. 23. 3o-o

4. 20. 7
5.58. 38

I9-55

o-o5

29

NI

6. 40. 59
8. 40. 9

2. I. 30'0
4. O. 2O-O

2. IO. O'O

3.54. 35-5

6.49. 17
8. 34. 10

21-09

21 -22

0-07

December i

NI

7. i5. 9

2. 27. 3o-5

2.33.20-5

7. 20. 44

24*10

9. ii. 18

4. 23. 20-0

4. 1 7. 40 • o

9. 5. 21

24-17

04

2

NI

8. 34. 24
10. 18.42

3.42. 3o-o
5.a6. 3o-5

3.46.50-5

5. 22. 10-5

8. 38. 28
10. 14. 4

25-70

0-04

4

NI

9. 32. 28
10.53. 2

4. 32. 20 -o

5.52.40-5

4. 38. 10-0
5.46.45-5

9. 38. o
10. 46. 47

27-95
27-97

0'02

6

T

17. 16. 33

o. ii. o'5

o. 54. 3o-o

17. 5g. 5o

29-21

18. 6.35

I. o. 54-5

0.57.34-5

18. 2.55

29-17

+ o-o3

7

T

17. i3. 10

o. 3.46-0

o. 18. 3-5

17.27. 10

29-94

17.57. 6

0.47. 35-o

0.43. 4-5

17.52. i5

+ 29-90

116

TRANSIT OF VENUS, 1874. HONOLULU.

Day,

Observer.

Time by
Transit-Clock
at Comparison
with
Chronometer.

Time by Chronometer at
Comparison with

Time by
Altazimuth-
Clock at Com-
parison with
Chronometer.

Altazimuth-
Clock slow .
on Apua
Sidereal Time.

Hourly Rate
of Altazimuth-
ClocV.

Transit-Clock.

Altazimuth-
Clock.

1874.
December 8

T

h ,„ . '
17. 6.38

ll IK. s

ii. 56.3i-5

h m s
0. 10. I'5

li in s

17. 19. 5o

+ 3o-68

s

17.47. 10
21. 57. 35

o. 36. 57-0

0.35. 7-5
5. 3.29-5

17.45. o
22. 5.53

30-72
30-98

+ o- 06

22. 1 6. 6

5. i3.2o-5

5. 6.38-0

22. 9. 2

30-99

i3

T

17. 5g. 3o

o. 29. 56- 5

j. 10. 42- 5 i 18. 40. o

34-44

18. 52. 12

I. 22. 3o'O

i. 13.45-0 18.43. 3

34-45

14

NI

o. 59. 48
2.48. 3o

7.25. i5-5
9. i3. 40-0

7. 3i. 5o-o
9. 8.io-5

I. 6. 0

2.42. 36

35-70
35-78

o-o5

i5

NI

2. 2. 3O
3.48.26

8.23.56-0
10. 9. 35-o

8. 29. 25-o
10. 5.5o-5

2. 7. 36
3.44. 17

36-40
36-43

O'O2

18

NI

4. 3o. 48
5. 58. 7

10. 40. iS-o

12. 7. 2O'O

IO. 45. 2O'O
12. O. O'O

4.35.29
5. 5o. 21

38-42
38-44

o* 02

19

NI

5. ii. ii

6.44. 3 1

ii. 1 6. 40-0

12. 49. 45'O

ii. 23. iS-o 5. 17. 22
i2.43.55-o 6.38.15

39-04
39-06

O'O2

20

NI

7. 12.37
8. 3o. 14

i. i3.55-o
2. 3i. ig-5

I. 2O. 25'O
2. 28. 23'O

7.18.43
8.26.53

(38-75)

O'OI

21

NI

7.41. 6
8.52.25

i. 38. 28-0
2.49.35-5

i . 44. 1 5 • o
2.43. io-5

7.46. 29
8.45. 34

40-19
40-24

o-o5

22

T

3.49. o
5. i5. 5o

9.43. 8-0
ii. 9.44-0

9.47. 37-0
ii. 4. 3g-5

3.53. 5

5. IO. 20

40-44
40-44

O'OO

24

NI

4. 27. 26
5. 35. 37

10. i3.45-o

II. 21. 45-O

10. 18. 25-o
11.17. 5-5

4.31.43

5. 3o. 33

41-11

41 • 12

O'OI

26

NI

6.41. 18

8. 2. 21

12. 19. 33'O
I. 40. 23'O

12. 22. 30'5

i.33.5o-o

6.43. 53
7. 55. 24

41-62

41-63

+ O'OI

27

T

1 8. 42.42

o. 19. I'o

o. 26.43-5

1 8. 5o. 3

41-84

29

NI

7.21. 7
8. 54. 5o

0.47.42-5
2. 21. ID'S

o. 52. 35-o

2. I6.25-5

7. 25. 38
8. 49. 42

42-38
42-35

— 0-02

3o

NI

9. 5. 58
10. 34. 17

2.28.25-5

3.56.3o-5

2. 34. 5-0

3. Si. 38-5

9. ii. 16

IO. 29. 2

42-99
42-82

- o-i3

3i

NI

9. 3o. o
ii. 6. 24

2. 48. 32-0

4. 24. 40 • 5

2. 52. 41-0
4. 19. 25'O

9- 33-47
ii. 0.45

43-57
43-58

+ O'OI

January I

HI

9. 58. 3g
ii. 25.48

3. i3. i5-5
4. 40. lo-S

3. 19. i5-5
4. 33. 37-5

10. 4. 17
ii. 18. 5i

44-36
-t-44'36

o-oo

TABLE VI. — ERRORS AND KATES OF THE ALTAZIMUTH-CLOCK (continued). 117

Day. «

a

£

0

Time by
Transit-Clock
at Comparison
with
Chronometer.

Time by Chronometer at
Comparison with

Time by
Altazimuth-
Clock at Com-
parison with
Chronometer.

Altazimuth-
Clock slow
on Apua
Sidereal Time.

Hourly Rate
of Altazimuth-
Clock.

Transit-Clock.

Altazimuth-
Clock.

i87S.
January 3

T

!i m s

19.46. 5;

h m M

o.56. 7-5

h m s

o. So. Sg-S

h in s
19.41.25

+ 45-17

-

7

HI

6. 56. 54
9. 4. 20

ii. 48. So'o
i. 55. 55-5

H.53. o-5

i. So. 35-5

7. 0.42

8. 58. 36

49-21
49-25

+ O'O2

8

NI

3.45. i5
6. 59. i

8. 33. 5o-5
11.47- 5-5

8.39. i3-5
ii. 42. 23-0

3. So. 16
6.53. 55

49-76
49 '75

O'OO

ii

T

2. 29. 25

4. 14. 5o

6.46. 5-o
8. 3i. i3-o

6.48.25-5
8.27.25-5

2. 3i. 24
4. I o. 40

5i-3o

5i-37

+ 0-04

i3

HI

3.49.41

5. 14. 35

7.58.25-0
9-23. 5-5

8. 2.27-5
9.20. o'o

3.53.23
5. ii. 8

52-3i

52-20

- 0-08

«4

NI

4.25. 1 3
6. 8. 7

8. 3o. o-5
10. 12. 38-o

8. 34.55-5

10. 8.22-5

4. 29. 48
6. 3. 3o

52-9O
52-97

+ o-o5

iS

T

4. 12. 5
6. 3i. 36

8.i3. 3-5

IO. 32. I2'O

8.25. 17-0
10. 28. 37-0

4. 24. o
6. 27. 40

53-17
53-18

o-oo

16

n

6. 2. 46

7.45.37

9. 59. 35-5
11.42. 10-0

10. 7.55-5

ii. 38. i5-o

6. 10. 47
7.41. 21

53-77
53-84

+ o'o5

"7

NI

5. 20. 25

6. 28. 56

9. 1 3. 3o-5
10. 21. 5o-5

9. 17.25-5
10. 1 6. 28-0

5. 24. o

6.23. 12

54-44
54-47

+ o-o3

18

NI

3. 9.49
4. 32. 3z

6. 59. 25-5
8.21. 55-5

7. 7.30-0
8. 16. i3-o

3.17.34
4. 26. 28

55-09
54-91

- o-iS

'9

NI

T

3.28. 0

4.53.28
10.45. 10
12. 14. 53

7. 13.43-0
8. 38. 57-5

2. 29.43-0

3. 59. ii -5

7. 16. i3-5
8. 34. i5-o
2. 32.40-5
3.52.45-5

3. 3o. 10
4. 48. 24
10.47.47
12. 8. 5

55-78
55-66
56-o3
56 -oS

— 0-09

+ 0-06
+ o-oi

20

T
NI

4. 22. 5
6. 2. 4

9- 24- 49
11.32.47

7.42. i9'5

9. 22. 2-5

o. 44. 1 5 • o
2. Si.52-5

7.47. 5o-o
9. i5. 25-o
o. So. 55-5
2.43. o-5

4-27. 1 5
5.55. 4
9. 3i. 9

II. 23. 32

56-73
56-8i
57-02
57-06

+ o-o5
+ 0-06

+ O'O2

21

T

5. 29. 40

7. 12.40

8.45.53-0

10. 28. 36-5

S. So. 14-5
10. 23. 59-5

5.33.40
7- 7-4°

57-99
58 -o5

+ 0-04

22

T

8. 0.45
9. 24. 54

II. 12. 43-0

12. 36.38-5

ii. 1 6. 25 -5
12. 3i. 8-5

8. 4. 5
9. 19. o

59-37
59-41

-f- o'o3

23

NI

5. 57.49
7. 34. 21

9. 6. i5-5
10.42. 32-o

9. 12. 3i-5
10. 36. 34-0

6. 3.42
7.27.58

60-54
+ 60- 60

+ 0-04

Q 2

118

TRANSIT OF VENUS, 1874. HONOLULU.

Day.

Observer.

Time by
Transit-Clock
at Comparison
with
Chronometer.

Time by Chronometer at
Comparison with

Time by
Altazimuth-
Clock at Com-
parison with
Chronometer.

Altazimuth-
Clock slow
on Apua
Sidereal Time.

Hourly Rate
of Altazimuth-
Clock.

Transit-Clock.

Altazimuth-
Clock.

1875.

h m s

h in »

h m 8

h m s

,

i

January 24

NI

7. 32. 3

10. 36. 23-o

10. 39. 55-0

7.35.II

+ 61-59

+ O'OI

9. 5. 32

12. 9. 37-0

12. 3.45-5

8. 59. i5

61-60

25

NI

8. 16.59

II. 17. 2O'5

II. 26. 2O'O

8.25.35

62-33

+ o'o5

9.59.45

12. 5g. 5o-o

12. 53. 3i-o

9. 53. o

62-40

27

NI

9. o. 58

ii. 53. 3o-o

ii. 58. 53-5

9. 5. 56

64-48

10.43.41

1.35.56-5

1.29. 7-0

10. 36. 24

64-54

+ 0-04

28

NI

5. 1 8. 48

8. 8. 4-5

8. 13.40-5

5. 23. 58

65-54

8.25.44

ii. 14. 3o-5

ii. ii. 5-o

8. 21. 5i

65-66

+ 0-04

29

NI

4-23.51

7. 9.25-0

7. 15.55-5

4. 29. 55

66-65

6.47. 12

9. 32. 23-o

9.26.47-5

6.41. 8

66-74

+ 0-04

3o

NI

5. 52. 17

8.33.45-5

8. 42. 17-0

6. O. 22

67-44

6. 45. 10

9. 26. 3o-o

9. 22. Si- 5 .

6.41. 3

67-49

+ 0-07

3i

T

6. 33. 17

9. 3g. i5-o

9.43. i5-5

6. 36. So

68-25

7.35.40

10. 41. 28-0

10. 36. 7-0

7. 29. 5o

68-25

o-oo

February i

NI

6.48. 8

9. 5o. 12-5

9.59. 5-5

6. 56. 34

69-01

7.47.20

10. 49. i5-o

10. 45. 40-0

7.43.16

69-02

+ O'OI

2

NI

5.55.49

8. 54. io-5

9. o. 1 5 • o

6. 1.26

69-58

7.23. 8

10. 21. i5'5

IO. 12. O'5

7. i3. 23

69* 64

+ 0-07

Time by

Altaz. Clock.

5

T

By Zenith distance of S Leonis, East, Table IX.

7.59.

70-87

8. 6.

71- 3o

o-oo

a Orionis ^^est

q. 3o.

71- 12

y* jw.

9.37.

. 71 '06

MEAN PLACES OP STARS.

119

TABLE VII. — CATALOGUE of tbe ASSUMED MEAN PLACES of STABS observed with the ALTAZIMUTH.

G refers to the Greenwich Catalogue for Epoch 1864; S to the Cape Catalogue for 1860; E to the First Melbourne
Catalogue, 1870; R to the Second Radcliffe Catalogue, 1860. Preference is given to the later observations at
Melbourne and Greenwich.

Star.

i

1874-0.

1875-0.

Seconds of Mean N. P. D. by various
Authorities, and Number of
Observations of N.P.D.

R. A.

\. 1'. D.

R. A.

N. P. D.

ft Ca«siopeiae ....

0. 2. 27'8l

0.19. 5-83

o. 20. 3- 14
o. 24. 1 1 • 96
o. 33. 22-o5

o. 37. 15-79

o. 37. 21-92
o. 41. 29-22
o. 49. 45-82
o. Si. 5^-05

I. 12. 38-29
I. 0.27-44
I. 2.40-92

1.33. i-ii
i. 45. 20-96

O / //

3i. 32.43-5
10. 38.45-1

1 32. 59. 24-25
24. 10. 36-6
34. 9. 14-65

108. 40. 43-2

15.42. 4-1
32. Si. n-5

52. II. 4-6

4. 25. 12-5
I. 21.45-2

137.23.37-8

55. 2.52-6
147. 52. 39-0

26.57. 5-9

21.56. 6-7
142. 14. ii-8
i3. 19.33-6
67. 8. 4-4
i38. 16. 12-9
73.44.45-7

44- 7-58-6

73.29.43-0
2.45.52-5

84. 27. iS-o

h m s

1.47.44-18

4. 3o. 41-48

5. 0. IO'2O

5.35. 7-4*

5.46.33-19
5.48. 24-27
6. ii. 36-58
6. 21. 10-55

6. 39. 38-29

6. So. 22-97
6. 53.42-80

0 / //

69. 48. 14-2
120.49. 9-5

112. 32. 25'4

124. 8. 3o'7

125.49. I'°
82.37. 5-45
36. 29. 39-0
142. 37.40-6

106. 32.46*9

io3. 53. 0-7
118.48. ii -8

G (1860) 6, 43"- 4; R 3, 43" -8.

JG 17, 45"' i ; G- (1870) i, 45"- 1;
1 (1869)2, 45"-o; (1871) 3,44"- S.

S i, 25"-2; E 3, 23"-9.
G6, 36"- 3; R4, 37"' i.
G 21, 14"- 5; R6, 1 5"- 3.

[G iS, 44"-o; S 122, 43"-i ; E 27,
I 43" -o.

G i5.
G 6, n"-i ; R 6, i2"-o.
G37.
G 10.
G 930.
S S, 38"- 1 ; E 3, 37"- 4.
Gi6.
S 27, 39"- 7; E 20, 38"- 1.

/G (i85o) 8, 5"-2; B. A. C., 5"-2;
I R5,7"'i-
649.
GzS.
S 2, i2"-i; E 3, n"-5.
G 5, 33"- 6; R 3, 33"'4.
G57.
S 7, i3"-2; E 3, i2"-o.
G 78.
G 12, (1869-72) 3, 8"-6 ; S i, n"-6.

/G 7, 26"-!; E 40, 25"-3; S 26,
t 25" -2.

G35, 58"-6; R9, 58"-7.

JG 7, 3i"-2; E 45, 3o"-9; S 39,
\ 3o"-3.

G4,2"-5. S 5, i"-3. £4,59"- 3.
G53.
G 5, 38" -9. R4, 39" -o5.
E 23, 41" -oS ; S 24, 40"- 1.
G 36.
G65,47"-3. S68,46"-6. E53,46"-9.

G 222.

Gi5, o"'7. Si, i"'2-
G 7, i2"-i. S 70, i2"-o. E So, n"-6.
G6i.

1 3 Cassiopeia? . . .
o Cassiopeiae ....

/3 Ceti . .

21 Cassiopeiae . . .
Tj1 Cassiopeiae . . .
,u Andromeda; . . .
2 Ursa: Minoris . .

$ Andromedae . . .
a Eridani

« Cassiopeise ....
$ Arietis

46 Cassiopeise . . .

1.46. 14-47
i. Si. 3-n

1.52.34-44
2. o. 4- 38

2. 22. 21 • 94
4.28.41-49

5. 7.22-99

47 Cassiopeiae . . .

1 68 Eridani . . .

o Tauri

a Aurigse
a Colunabae .....

£ Columbae

a Orionis

4$ Aurigse

y Geminorum . . .

6. 3o. 25-90

6. 40. 44-90
7. 32.42-31

ju Canis Majoris . .
f Cartis Majoris. .
a Canis Minoris .

120

TRANSIT OF VENUS, 1874. HONOLULU. TABLE VII. (concluded).

Star.

1874-0.

1875-0.

Seconds of Mean N. P. D. by various
Authorities, and Number of
Observations of N.P.D.

R. A.

N. P. D.

R. A.

N. P. D.

j8 Geminorum . . .

h in s

77.25. 4-0
69. 31/19-3

32.56. 33-o
68.47. 10-8

80. 34. i • 9
89. S?. 5g-o
5.54. 8-0

100. 3o. 10-6
io5. 3i. o-i5

3.23.34-1
116.27. 3-2

I. 4. 17-5
96. 7.27-9

106.41. 5i'7

90. 55. 51-9
137. 34. n-o
98.24.35-7
90. 39. So- 1
90.45.58-5
137.32. 33-3

120. I?. 21-9
96.43.40-2

128. 3o. 52-6
1 3. 4. i5-2

118. 49. 36-6
83. So. 3-8

It m »
7. 37. 39-86
7.44. 2 '22

8. 29. i5'49
8.43. 3-6i
S. So. 38-42
9. 13.44-60

11.42.40-94

1 6. 14. 24- So
1 6. 58. 50-72

20.13. 3-57

22. 58. 32-o8

61. 40. 25-75
114. 32. 49-85
25. 14. 16-6
27. 34. 1 8 • 8
41. 28. 9-9
148.45. 4-0

74.43.45-4

1 3. 48. 3i'9

7.45.37-3

12. 39.57-5
75.28. I' I

049.

G 2, 5o"-o; S 2, 49" -7.
G 5, 17"-!; (1871-2) 7, i6"-2.
G 3, 19"' i ; E 5, ]8"-6.
G 4, io"-o. R 9, 9"-8.
Ei6, 3-"7. S3, 5"-7.
G7i.
627.

/G (1869) 6, 32"- 7; G (1870) 4,
\ 33"-o; R 6, 33"- 3.

648,
G 38.
G 14.
G 19.

G(i873)4.

JG io5, io"-6; S 118, io"-6; E 26,
\ 10"- 6.

JG 3g, 6o"'4; E 3o, 6o"-o; S 92,
\ 60"- 1.

G 10, 3i"-5; R4, 32"- 8.
G (1860) 81.
G 204.
E 4, 2"'9i ; S 40, 3"-2i.
G84.
G z5, (1868-72), 9.
627.

/G 3, 53"-i ; S 21, 5i"-6; R 8,
1 5i"'6S.

G 14.
E 3o, n"-o; S 18, n"-o.
G37.

G 12.

aii.

E 3, 32"- 3 ; S 7, 33"' 7.

/G 3o, 22"- 8; R n, 21"- 8; E 53,
1 2i"'7; S 123, 2i"-8.

G 22.

JG 7, 40"' 6; R 6, 39"'7; S 10.
1 40" -2.

84, 52"- 5; E 3, 52" -8.

G27.

/E 35, 36"-3 ; S 16, 36"'7; G 9,
1 37" '5.

G 23.

if Ursse Majoris . .

5 Ursse Majoris . .
i Ursa; Majoris . .

10. I. 39-56

10. 1 3. i-36
10. 54. i3- 52
n. 7- 24'29

II. 58.47-43
12. 1 3. 27-55
12.48. 13-25

i3. I8.33-37
14. 43. 54-62

18. 12. 58-91
1 8. 47. 27-08
19. 5o. 18-84

£ Ursse Majoris. .

£ Leonis

Bradley ijli. . . .

o2 Libras

1 9 Ursse Minoris .
6 Ursoe Minoris . .
5 Ursa; Minoris . .

\ Ursa; Minoris .
KI Cephei

21. 24. 55-43

21.40. 4-98
21. 59. iS-63

22. 0. 16-90
22. IO. IO'97
22. 22. 20-46
22.28. 52-82
22.35. 8-02

22. 5o. 40-99

23. 7-47-77
23. 26. 12-54
23. 34. n-58

23.42. 21-56
23. 52. 50-47

S Capricorni ....

ft Gruis

$ Sculptoris ....

8 Sculptoris ....
<a Piscinm

121

TABI.K VIII. — OBSERVATIONS of STARS for the COLATITUDE of the ALTAZIMUTH PIER at HONOLULU,

and of COLLIMATOKS for ZKNITH POINT.

122

TRANSIT OF VENUS, 1874. HONOLULU.

TABLE VIII. — OBSERVATIONS of STABS for the COLATITDDE of the* ALTAZIMUTH

Da>

Observer.

Star.

Time by
Altazimuth-
Clock.

b

O

1=

g

-<£

S ^
• "

h!

Circle-Reading
corrected for
Runs of
Micrometers.

•Level
Indication
(additive).

Refraction
(additive
when
Lamp L).

1874.
October 2

3
5

6
10

NI
NI

T

N:

NI

h m s

23. 54.48
o. 3. 10

21. 16. 26

21.28. 28

21.55. 3

22. 2. 26
22. 26. 45
22. 33.48
22. 45. 9

22. 53. 7

22. 3. 21
22. IO. 5

22. 19. 38

22. 25. 12

22. 33. 19

23. 5.17
22. 44. 57

22. 5o. 49
23. 24. 36
23. 3i.25

21. 19. 12

21. 27. i3

21.53.48
22. 2. 2
22. 7. 38
22. I 5. IO
22. 22. 59
22. 29. 5 1

22.45.' 7

22. Si. l8

II

R

I
R
U
L
L
R
R
L

L
R
R

L

R

L

c

R

L
R

L
R
R
L
L
R
R
L
L
R

L
R
R
L

o / //

285. 7-5o-4
254. 38. 24-7

297. 3o. i5-3
242. 34. 3o-i
247.44.26-9
292. 1 3. 14-4
291. 57. 46-8
247.55. i3'4
218. 24. 29-4
321. 33. 40-0

338. 49. 40- 3
201. 7. 47- 8
248. 2. 8-5
. 292. 3. 54-0

202. 22. l3'3

337. 3o. 33-4
32i. 34. 3i- 1
218.25. So- 1
325.37. 16-6

214. 22. 48'3

297.26. o-3

242. 34.27-5
2OI. 9. 24-6

338.49. 30-9
299.41. 38-6
240. 1 6. 9-6
248. 2.25-6
292. 3. 4-7
32i. 34. 24-2
218. 25. 50-4

4.17. 6-1
175. 42. 24-6

176. 2. 2O-7

3. 57. io-3

//
74'4
66-2

75-o
65-2
63-7
71-8
74-6
63-6
62-6
73-5

76-4
65-6
65-4
76-2
74-6
66-4
76-1
64-8
67-4
76-0

76-1
67-2
64- 1
71-6
72-8
64-4
64-0
75-4
76-4
63-7

74-3
66-3
54-9
87-6

i5-i

i5-3

29-0
28-9

22-8
22-8
22-5
22-6
70-1
70-1

I42-3
I42-5
22-4
22-5

133-9

133-2
69-9
69-9
81-0
80-9

28-8
28-8
142* i
142- 1

32-0
32-1

22-4

22-5
69-8
69-8

j8 Aquarii

a Piscis Australis

V) Aquarii

a Piscis Australis

a Piscis Australis

E. Collimator . . . .

October 6, 6 Aquarii, Lamp R. The Circle-Reading has been increased i'

TABLE VIII. — OBSERVATIONS FOR CO-LATITUDE.

123

PIER at HONOLULU, and of COLLIMATORS for ZENITH POINT.

Barometer
and
External
Thermometer

Zenith Point for
Center Wire, including
Zero of Level.

Concluded Zenith
Distance.

Reduction to
Meridian.

Tabular
Apparent N. P. D.
of Star.

Colatitude.

Observed.

Adopted.

270. o

270. o

„

„

0 / //

/ //

0 , //

O / If

3o'"-i8

5i-i

5i-8

1 5. 8.28-1

0.47-5

83.49.43-9

68.42. 3-3

72° -8

» ?

i5. 21. 36-2

13.54-2

"

42. 1-9

5i-6

, ?

27. 3i. 7-5

5.49-7

96. 7. 17-6

41.59-8

,,

27.25.45-4

o. 27 • 3

,,

4I.59-5

5i-i

> »

22. 1 5. 44* o

2. Q * O

90.55. 38-2

42. 3-2

» »

22. I 3. 57-2

0.23-6

,,

42. 4-6

I r

,,

21. 58. 32-1

i. o-5

90. 39. 35-o

42. 3-4

J 2 4 I

,,

22. 4. 57-4

i. 18-9

90.45. 43- 1

42. 4-6

3oin-24

52-2

,,

Si. 36. 29-9

1.23-5

1 2O. 17. I I'D

42. 4-6

73°'9

"

5i.35. n-8

o. 4-7

"

42. 3-9

54-9

53-i

68.52.25-9

o. 14-9

137.34. 9'3

41.58-3

75°-3

,,

68. 54. 22-2

2. I4'8

,,

42. 1-9

*

} 5*'5 {

J t
y >

21.58. 1-6

22. 4. 39-6

o. 28-0
o. 55-i

90. 39. 35-o
90.45.43-1

42. 1-4
41.58-6

—

55-o

67. Sg. 4I'O

I. 21. 32'4

42. 3-9

—

,,

67.32.58-0

» j

42. 4-2

3oin-z3

5i-7

53-i

Si. 36. 4-0

o. 5g- 1

120. 17. n-3

42. 6-4

75°-5

J »

5i.35. 8-1

o. 0-4

j »

42. 3-6

54-2

t t

55. 38. 5i-9

o. 43 • I

i3. 3.55-9

42. 4-7

"

55.38. 9-7

o. 3-0

"

42. 2-6

50'2

, ,

27. 26. 52-1

1.43-6

96. 7.17-7

42. 9-2

, ,

27.25.47-2

o. 33-o

J J

42. 3-5

55-o

,,

68. 52.46-5

o. 46 • o

137. 34. 9-4

42. 8-9

, ,

68.52. ii -5

o. 7-3

> j

42. 5-2

53-o

,,

29.42. 3o'3

o. i3-6

98. 24.23-1

42. 6-4

> >

29.44. 11-4

1.54'S

,,

42. 6-2

\ 8-5 -[

,,

21. 57. 45-9

o. 7-7

90.39.34-9

41.56-7

72° -7

J 4 t

,,

22. 3.49-5

o. 12-4

90. 45.43-1

42. 6-0

54-2

,,

5i. 35.57-3

0.49-3

120. 17. £I'4

42. 3-4

3o'"-o3

"

Si. 35. 8-8

o. 3-i

j t

68.42. 5-7

—

55-6

56-o

94. 17. 24-4

,,

94. 17.25-1

56-7

,,

93.57.40-5

i »

93.57.41-9

~

~"~~ '

' ' " """'

124

TRANSIT OF VENUS, 1874. HONOLULU.

Day.

I

Observer.

Star.

Time by
Altazimuth-
Clock.

b

o

1

l3

Hi

Circle-Reading
corrected for
Runs of

Micrometers.

i

Level
Indication
(additive).

Uefraction
(additive
when
Lamp L).

1874.

E Collimator

h in K

I,

3.57. 8-r

//
88-4

„

It

176. 2. 21 "4

52-7

NI

S Colliroator . .

Ji

175. 40. 26' 3

64-8

L

4. 17. 49" 7

73-o

I.

3. 57. 28-2

83-6

B1

176. 0.46-3

55-2

i3

NI

S. Collimator

B

175. 41. 37-2

63-o

I,

4. 1 6. 42 • i

76-2

t

3.56.27-4

85-4

B

176. 1.48-0

56-8

16

NI

23. 6. 55

It

2C2. 28. 33-9

73-6

i3z'9

23. 36. 5o

J,

337.24.4I-3

66-0

i32'4

23.47. 2

K

202.35. 3-8

75-2

l32'2

o. 3. 16

L

337. 21.25-0

64-2

l32'0

0. 10. 12

It

202. 37. 35-6

76-2

i3i"9

0. l6. 52

L

337. 20. 1-6

65-5

:3i-8

18

NI

L

4. 14. i3-5

72- 1

B

175.44. 1-4

69-6

E. ColHmator

L

3.56. 6-4

78-4

B

176. 2. 9-6

62-2

22

T

E Collimator . • .

It

175. 5o. 4-8

69-0

L

4. 8. 12-6

72 "o

175. 5o. 7 - o

69-5

. '

t

4. 8.12-5

71-4

2"

T

i. 3o. 41

K

190. 53. 21*2

73-7

270' 3

1.35.58

L

349. 5. 9-5

65-5

27P'4

2. 0. 2O

L

337. if). 59- 5

76-6

I 32* 2

2. 16. 8

1,

76-6

I 32" 2

2. 24. 1 5

K

202. 36. 38'7

l32'Z

f

2. 3l. IO

Jt

202. 35. So* 7

63-7

i32-3

3o

NI

S C > iiinator

K

175.41. 56-6

75-8

L

62-7

October n. Adjusted wires for horizontality.

October 22. Adjusted the foot-screws. The pier was slowly settling and inclining to the eastward.

TABLE VIII. — OBSERVATIONS FOR CO-LATITUDE (continued}.

125

Barometer
and
External
Thermometer

Zenith Point for
Center Wire, including
Zero of Level.

Concluded Zenith
Distance.

Reduction to
Meridian.

Tabular
Apparent N. P. D.
of Star.

Colatitude.

j Observed.

Adopted.

0 /

0 /

270. o

270. o

//

„

o / //

/ tr

0 / /,

° / //

55-2

56-o

93. 57.40-5

—

••

93. 57.41-9

94. 18. 45-6

17-0

16-8

» »

94. 1 8. 46-0

—

—

16-6

J J

93. 58.35-0

—

—

J 1

93. 58. 35-4

—

19-2

J9'O

94. 17. 38-8

—

,,

94. 17. 39-3

—

iS-S

, ,

93. 57. 33-8

—

—

» t

94.57. 34-a

—

75°-6

iS-5

67. 3a.43'9

....

I. 21. fcg'I

68.42. 7-1

> >

67. 27. 41-2

....

» »

42. 3-4

» >

67. 26. n'7

....

» »

41. 58-6

» j

67.24. 22-7

....

f i

42. 5-9

3oiu-i5

? >

67. 23. 38-6

....

» >

42. 3-9

75"' 3

» »

67.23. 0-4

j >

42. 2-5

18-4

i8-3

94. i5. 7'3

) >

94. 1 5. 7'3

iiJ-3

> *

93.57. 6-5

> >

93.57. 6-5

19-2

2O '2

74° '7

iS-5

i5-5

79. 10. 19-9

o. 0-8

147. 52.24-2

42. 5-i

j »

79. 10. 38 -9

o. 18-9

1 >

42. 4-2

i5-5

j ;

67.23. 12-8

....

I. 2I.23'6

42. 2-1

, ,

67. 23. 56-2

....

* >

42. 7-3

3o'"' • 20

,-.

67. 24. 45-0

...»

J »

42. 4-7

74' '5

> »

67. 25. 33-4

J »

68.42. 4-9

i6-5

— ~— "

R 2

126

TRANSIT OF VENUS, 1874. HONOLULU.

Day.

Observer.

Star.

Time by
Altazimuth-
Clock.

I*

o

i

a

0.*

Ja

Circle-Reading
corrected for
Runs of
Micrometers.

Level
Indication
(additive).

Refraction
(additive
when
Lamp L).

1874.
November 3

T

£ Gruis

ti ra I

22. 38. 23

L

0 f ff

338.47. 45-1

//

22.45. 33

R

201. 7. 37 • 6

66-q

22. 5i. 44

R

21 8. 24. 46-8

66-6

69'5

22. 59. 24

I,

3zi. 36. 5o-8

73-4

23. 16.43

L

329. 47. 43-4

74' 8

23. 24. 39

R

2IO. 12, 2' I

66-6

z3.33. 3

L

325.36. 3-o

68-4

80*6

23. 38. 53

R

214. 21. 47' I

71 • i

8o'6

£ Cassiopeia?

23. 4.7. 57

R

232.45. 43 '2

70*4.

z3. 53. 9

R

232. 48. 27 '0

70' 7

o. o. 1 3

L

307. 8. i3'7

678

41 • 8

o. 7. o

L

307. 9.18-3

67-8

Bradley 1731 S.P

o. 1 7. 40

L

*344. 26.41-8

69- o

IQ5-8

o. 25. 5 1

R

195.27. 6-6

7° '4

i. 6. i5

L

338. 39.21-8

74' '

1. 13. 19

R

201. i5. i6'o

66-0

i. 21. 38

K

190. 5i. 56-o

65-2

j.26.55

L

349. 5. 5-2

73-o

278-5

i. 32. 3o

L

349. 4. 48 • 2

73-8

278*4.

i. 37.43

R

190. 52. 37-6

65-8

278*7

4

T

E. Collimator

L

3.55. 54-9

74-5

R

176. 2. r5'6

66-8

6

NI

O. 2. 2

R

2o5.35.4i-5

64-8

iiS-i

o. 7. 3o

L

334. 18.21-6

71-6

I IA* 7

o. 1 6. 34

R

205.43. 33-2

66-3

0.21. 38

L

334. 14.28-5

71-8

c Cassiopeia;

i. 16. 55

L

3l2. Q.35'9

70-8

I. 23. 12

R

228. 4.14-8

70-6

1. 19. 1 5

L

349. 5. 3-5

71-6

I. 35. 2

R

190. 53. 19-6

i. 48, 17

R

196. 3o. n-3

66-3

2. 8. 24

L

343. 33. 38-7

?3'2

i85' 5

1 68 Eridani

2. 1 6. 8

L

33g. 3i. 18-4

2.21. 58

R

200. 27. 44-4

68-7

7

NI

E. Collimator

R

175. 58. 5o-2

62-8

L

3. 59. 20-9

75-8

q

NI

o. 33. 3

L

3od.. 3 1. 4.4.* ft

38'2

H

235.25. 8-1

68-0

38*2

Bradley 1731 S.P., lamp left, supposed to have been observed on wire B ; the circle-reading requires to be increased 3'. 6"- 8.

TABLE VIII. — OBSERVATIONS FOE CO-LATITUDE (continued).

127

Barometer
and
External
Thermometer.

Zenith Point for
Center Wire, including
Zero of Level.

Concluded Zenith
Distance.

Reduction to
Meridian.

Tabular
Apparent N. P. D.
of Star.

Colatitude.

Observed.

Adopted.

0 /

0 /

270. o

270. o

//

//

o / //

/ //

0 / //

° / ff

7*°'4

«4*7

i4'6

68.5i. 6-1

0.35-3

137. 32. 32-8

68.42. 2-0

* »

68. 53. 5i'9

3.21-2

> >

42. 2-1

i3-8

» »

5i.35. 3o-7

o. 17-9

120. 17. lS'0

42. 2' 2

> >

5i.38. 59-3

3.48-0

» >

42. 3-7

16-1

, ,

59.5o. i8-3

i. 35-i

128. So.45'5

42. 2-3

29in'97

, ,

59.48.40-5

0. 0-2

) J

42. 5-2

7z° -7

16-0

» »

55.38.i7'4

o. o-3

i3. 3.46-5

42. 3-6

> »

55.38. 37-0

O. Z2 • o

} »

42. i-5

i3-o

j >

37.14. 3-o

4. 10-8

3i. 32. 15-4

42. 7-6

> >

37. n. 17-9

1.26-3

J J

42. 7-0

12- I

, ,

37. 9.48-7

O. O'2

3i. 3a. i5'4

42. 3-9

> »

37. 10. 53'4

I. 6-2

» i

42. 2-6^

i5-6

» »

74. 33.58-8

2.38-3

-5.54. 32-7

42. 0-4

» >

74-35.14-5

I. 20*5

> »

42. 2-3

29™ -99

i4-3

> j

68. 42. 41 -9

1. 18-9

137.23. 25-6

42. 2' 6

72° -2

» »

68.46.13-6

4. So- 1

J J

42. 2-1

l5'2

»l

79. ii. 5a-5

I. 29-0

147. 52. 26-1

42. 2-6

> »

79. 10. 42- 1

0.17-4

J )

42. I'4

. l3'2.

j »

79. 10. z5-8

o. 1*9

J »

42. 2 ' 2

» »

79.11. 9-9

0.43-2

> >

4I.59-4

i5-8

—

74° -o

14-5

16-6

64. 25. 25 '4

8. 8-7

i32. 59. i5-o

41.58-3

» »

64. 21. 1 1 • 3

3.58-9

» »

42. 2-6

18-0

» »

64. 17. 3i-5

0.19-4

> i

42. 3-9

» >

64. i<j. 18-1

o. 3-i

> >

42. o'o

IJ-7

> >

42. 2. 2O'O

16.52-2

26. 56. 41*0

42. 8-8

1 1

41. 55. 40-9

10. 17-0

> »

42. 4-9

16-0

» j

79. 10.37-5

o. 1 5 • i

147. 5a. 27-0

42. 4' 6

» >

79. 10. 27-0

o. 3-5

i »

42. 3-5

I7-4

» j

73.32. 3-4

o. 9-9

142. i3. 57'2

42. 3-7

» >

73. 37.40-8

5-45-7

j ;

42. 2' I

3o""i6

16-2

» »

69. 34.43- 1

o. 52' 7

i38. i5. 56-i

42. 5'7

74°' 3

» j

69. 33.5o-7

o. 0-4

) J

42. 5-8

14-9

—

73>-6

i7-5

16-6

34. 33.20-6

o. o'3

34. 8.45-8

42. 6-1

> »

34.34. 38-7

I. 20-1

,,

68.42. 4-4

128

TRANSIT OF VENUS, 1874. HONOLULU.

Day.

Observer.

Star.

Time by
Altazimuth-
Clock.

c

."So

•^«t-

JF

Circle-Reading
corrected for
Runs of
Micrometers.

Level
Indication
(additive) .

Refraction
(additive
wheu
Lamp L).

1874.

NI

h in s

0 / //

253 28 2-6

//

i6-5

L

286 33 38-3

16-5

i 8 10

33? 17 36-7

72-3

i3i -8

68-4

i3i -8

10

NI

L

60*6

n

175 46. 3o- o

ii

176. 8. i3'8

5i-8

L

3. 4.Q. So '4-

88-5

23 33 So

L

3i5.36. 0-6

76-2

81 -5

23 41 28

R

214.. 21. 4.7 ' Q

66-2

Si-5

23 5o 3o

L

32o. 7. 46^4

66-4.

66-8

11

219. 41. 36- 3

67-1

o 19 38

I,

314. 3o. 27' 5

75-8

o. 26. 6

R

225.28. S-z

66-2

54- 9

& Ceti

O 35 47

R

23o. r. iS-2

73-3

46-6

J,

309. 57. 37 ' o

4.6-5

NI

o. 17. 36

L

314. 3o. 53-5

75-8

54'7

R

225. 28. 7'4

67-2

54-7

o. 32. 3i

R

235.26.26-8

65-7

38-3

o. 3y. 3*

1,

304. 32. 14' S

73-8

38-3

I. 2. AQ

E

202. 40. 34' i

65-2

I 32' 2

I. 7. 5

R

202. 40. 33-5

65-8

132-1

I. 14. 10

L

337- 17. 33-4

75-o

l32'I

I. 10, 28

t

337. 17.33-4

75-o

l32'I

I. 28. 57

L

349. 5. IO'2

69-3

270-8

I. 34. 2

R

190. 53. i9'7

74'5

279-6

R

223. i3. 44-7

66-4

So* o

i. So. 3z

L

3i6. 44. 41 • 5

73-8

5o ' o

o. 28. 56

R

235. 26. o'4

61-8

38-6

o. 35. 14

L

304. 3i. 47'2

76-4

38-6

o. 40, 3

L

3o5. 49. 44-4

77'4

40-6

o. 46. 1 3

R

234. 7. 54-4

63-S

40- 6

j. o. 5o

R

202. 40. 36* 3

63-o

i33-5

j. 6. 10

L

337. 17. 34-2

77-2

i33-5

i. i3. 46

R

202. 40. AI • 2

65-o

i33-6

i. 19. i3

L

337. 17. 29-6

77'3

133-7

i. 27. 16

K

190. 52.44-0

76-2

283-6

i. 32. 38

L

349. 4. 52-7

64-4

283-5

TABLE VIII. — OBSERVATIONS FOR CO-LATITUDE (continued).

129

Barometer
a:id
External
Thermometer.

Zenith Point for
Center Wire, including
Zero of LeTel.

Concluded Zenith
Distance.

Reduction to
Meridian.

Tabular
Apparent N. P. D.
of Star.

Colatituda

'. Miswved.

Adopted,

o /

0 /

270. o

270. o

i

/,

0 , „

t ft

0 / //

0 / //

17-4

16-6

i6.3i.23-S

o. o'o

32. 10. 37-5

68. 42. -i • o

J )

16. 34.48-3

3.23-2

,,

42. 2-6

3o'" • 1 5

iS-S

J »

67. 20. 44 '2

0. I'2

I. 21. 19- I

42. 2'I

74° -o

J >

67. 20.44-7

O. O'O

> >

42. 3'8

16-4

—

—

16 7

—

• —

69° '2

i8-5

17-6

55. 38.20-7

o. o- 1

i3. 3.44-7

42. 5 • 3

, ,

55. 38.45'o

o. 26- 3

> > •

42. 3-4

18-6

, ,

5o. 9.42-0

2. 17-0

1 1 8. 49. 26 '6

42. 1-6

> »

So. 18. 34-2

II. 9-1

, ,

42. i • 5

i9-3

> )

44. 32. 20-6

o. 22-7

24. 10. 6-9

42. 4- 8

j j

44. 3i. 58-i

o. 3-6

? i

42. 1-4

3oin-i4

i5-8

» >

39. 58. 32-7

o. 6-2

108. 40. 27-2

42. 0-7

73°-2

j >

39. 59. 14-9

0. 52'I

» j

42. 4-4

7I°-0

i8-5

16-6

44- 32.47-4

o. 46* 9

24. i o. 6-6

42. 7-1

J )

44. 3i. 56-7

O. O'O

i j

42. 3-3

iS-9

J J

34. 33. 22-4

o. i -4

34. 8.45-4

42. 6-4

II

34.33.5o-3

o. 3o-8

» t

42. 4-9

i5-4

M

67. 20.49-5

o. 5-i

I. 21. l8'2

42. 2' 6

' j

67.20.44-4

o. 1-8

I )

42. o'S

17-2

) >

67. 20. 43-9

O. O'O

> »

42. 2' I

i )

67. 20. 43-9

o. 1-8

J >

42. o-3

19-0

> »

79- 10.42-7

o. 16-7

147. 52.28-3

42. 2-3

».

79. IO. 22-O

o. 0-9

,|

42. 7-2

$•"••13

i$-9

>i

46. 46. 24- 5

0. 2'2

21. S5.40-6

42. 2-9

73° -i

> >

46.46. 37-7

o. 16-9

> >

42. 1-4

65°-o

17-5

16-6

34. 33. 53-o

o. 35-6

34. 8.45-2

42. 2-6

> >

34. 33.25-6

o. 6-3

, ,

42. 4-5

17-1

» >

35. Si. 25-8

o. 3-5

32. So. 42-5

42. 4-8

63"'4

> )

35. Si. 59-0

o. 37-8

> >

42. 3-7

17-8

1 *

67. 20. So- 8

o. 7-2

I. 21. 17-9

42. i-5

,,

67. 20. 48-3.

a 2-3

* »

42. 3-9

-5-7

> i

67. 20. 44-0

o. o-o

» >

42. 1-9

j j

67. 20. 44-0

o. 1-7

, ,

42. 0-2

3o'"-oi

iS-o

> »

79. ii. o-o

o. 33-o

147. 52. 28-6

42. i • 6

63°-2

"

79. 10. 24-0

O. O'2

) J

68.42. 4-8

130

TRANSIT OF VENUS, 1874. HONOLULU.

Day.

Observer.

Star.

Time by
Altazimuth-
Clock.

0

s

60

&

g-'S

I"

Circle-Reading
corrected for
Runs of
Micrometers.

Level

Indication
(additive).

Refraction
(additive
when
Lamp L).

1874.
November 1 3

NI

a Cassiopeise .

h m s

o. 29. 26

R

o tit

235 26 8-2

//
64-6

38"7

o. 35. 56

L

304 3i 53- i

T^'^

38*7

2 UrssB Minoris

L

L

77 2

o. 55.25

R

ao5. 43. 5i * 6

77 4
64*6

I. O. I

K

I. 7. 4.2

R

4/

i33*5

I. 12. l8

R

fi^ • /i

i33*5

I. 17. 5o

L

337 17 3Vo

1.23. 3i

I,

337 17 37'8

ȣ. 9

i33'4

i. 3i.5i

R

282-5

1.38. 7

L

66'2

282-6

24

NI

S. Collimator . .

R

So1 6

L

fil'fi

December 3

NJ

S Collimator

K

L

61*4

R

iy5 45 33'i

L

79 9

l«

NI

S. Collimator

L

4. 17. 33-5

56'T

R

9,1 . n

1875.
January 7

NI

7. 4.2. AO

L

3 1 5. 4.Q. 1 5 "4.

^2,'A

58-4.

7. 4.8. 4.0

R

224. 8. S'o

01' 1

58-5

K1 Cephei S.P. . .

7. SQ. 14.

JL

35i. 13.45-6

oV1

353-0

8. 4. 2

t

35i. 14. 28*6

353-6

8. ii. 14

R

l88, 4.3. 27'4.

^A'7

353-9

8. 1 5.40

R

188.43. 3i'o

53*4.

353-0

'

8. 25. 28

H

2,26. 32. 2Q ' 2

53' Q

53-Q

8. 32. 19

L

3i3. 26. i '9

8.41. 58

I

3u. 5.43'6

AQ-8

8. 48. 58

R

228. 5 1. 44* 3

52-8

AQ- 8

8

NI

5z "Eridiuii

Ai 3o. 44,

t

322. 5. 12' O

72-5

4. 36. 5i

R

217. 5 1. 37*2

72-6

4.. 57. 7*

R

226. 9, 3 1 ' 6

54.' 3

5. 3. So

L

3i3. 49. 3i-3

68-2

5. 28. 25

L

325. 25. 19-5

82-2

5. 36. 25

U

214. 33. 58-6

82-2

5 Si 55

87-6

TABLE VIII. — OBSERVATIONS FOB CO-LATITUDE (continued).

131

Barometer
and
External
'hermometer.

Zenith Point for
Center Wire, including
Zero of Level.

Concluded Zenith
Distance.

Reduction to
Meridian.

Tabular
Apparent N. P. D.
of Star.

Colatitude.

Observed.

Adopted.

o /

° /

270. o

270. o

//

//

o / //

/ //

O I If

0 / //

i8-5

16-6

• 34.33.42-5

0.27-8

34. 8.45-0

68.41.59-7

65°-o

> >

34. 33. 3o-5 o. 12-1

> >

42. 3-4

I9-2

> >

64. 17. 3o'7 o. 9-5

4.24.43-4

42. 4-6

14-4

? »
> >

64. 17. 2i- 1
64. 17. 16-4

o. i-3
o. 1-8

> »
) )

42. 4-2

41.58-0

» j

64. 17. 26-0

o. 10-0

» *

41. 59-4

16-8

» >

67. 20. 46-8

o. 1-4

i. 21. 17*5

42. 2-9

» j

67.20.44-9

o. o-o

> >

42. 2-4

17-0

, ,

67. 20.46-7

0. I'l

» >

42. 3-i

» *

67. 20. 5o-9

O. 5'O

j »

42. 3-4

3o'n-iz

16-1

) >

79. 10. z5' 6

o. 1-4

147. 52.28-8

42. 4-6

67°-2

> >

79. 10. So- 1

o. 26-9

j j

42. 5-6

:5-6

—

—

—

i8-3

—

—

—

17-4

—

—

—

16-0

—

—

—

58°-2

26-5

25-6

4$. 5o. 40-6

o. 0-7

114. 32.42-7

42. 2-8

* >

45. 51.46-6

I. 8-5

* »

42. 4-6

22-3

» >

81. 20. 46- 3

I. 7-4

12.40. o-o

4i.53-7

) >

81. 21. 3i-3

o. 26-6

> >

41.57-9

25-7

J »

81. 21. 57-4

o. o-3

1 >

41. 57-7

> )

81.21. 55-1

o. 5- 1

» »

4X. O ' 2

25 '3

, ,

43.27.57-3

o. 10-4

25. 14. 16-7

42. 3-6

» »

43. 28. 2-9

o. 16-6

» >

42. 3-o

3oin-o3

26-1

» »

41. 7-42'°

o. o-i

27. 34- 20-0

42. 1-9

55°-8

9 >

41. 8.38-3

o. 57-4

» j

42. 0-9

63° -5

24-5

24' 6

52. 7. 10-0

o. 1-4

IZ0.49. IJ'6

42. 3-o

J »

52. 8. 45-6

1.36-7

» >

42. 2-7

22-4

) J

43. 5o. 36-9

0. 12-2

JI2. 32. 24-6

41.59-9

J »

43. Si. 9-3

o. 49 • o

» >

42. 4-3

60° • i

24-4

» »

55. 27. 29-3

i. 3-9

124. 8.29*6

42. 4-2

, ,

55.26. 33-8

o. 8-1

, ,

42. 3-9

25-9

1

» I

57- 7.59-8

i. 7-3

I25.48.59-5

68.42. 7-0

132

TRANSIT OF VENUS, 1874. HONOLULU.

Day.

Observer.

Star.

.Time by
Altazimuth-
Clock.

o

S

.y

ri
gt-?

Circle-Reading
corrected for
Runs of
Micrometers.

Level
Indication
(additive).

Refraction
(additive
when
Lamp L).

1875.

NI

h in a

5 5y 12

327 8 35-7

//
67-8

87-8

5 Ursa Minoris S.P. . . .
» » • • •
» > * • •

Cepbei 5i

6. 4. 56
6. 10. o
6. 17. i
6.21.48
6. 3?. 4.0

R
It

I,
L
L

197. 56. 24-0
197. 56. 22-5
342. 2. i • 9
342. 1.52-7
335. 53. 19-4

69-0

68-3
74-1
74-8
75-4

173-4
i73-5
173-6
1-3-6
126-5

6 43. 38

R

204. 5. 2*8

60-6

i5

T

S. Collimator

It

175. 24. i • 5

63-5

L

78-5

175. 24. 6-8

63'7

L

4.. 34.. 8'2

78-9

28

Nl

5 46 4$

338 Q 56-4.

i38'7

5. 5z 38

L

338. 12. 3-i

7O '4

138-9

5. 57. 35

It

2O I. 44. 40* 2

73-0

1 3o - 1

6. 2. i 8

It

201. 43. 6* 9

73-1

i3q-3

5 Ursae Miuoris S.P. . . .

6. 8. 5o
6. i5.43
6 21 28

R

L

197.56. 6-3
342. 2. 14-1

72-2
69-4

6q- 2

170-7
170-7

6. 25. 58

L

343.52.20-5

73-8

190*9

6 32 34

73-0

6. 37. 17

It

204. 4. 49 • i

73-5

124*3

6.44.. 53

L

335. 53. 33-7

71 -o

6. 49. 40

L

335. 53.40-1

72-2

124-3

M

NI

A Ursse Minoris S.P. . . .

it ...
» > • • •

» » • * •

, , ...

Polaris ,

7.36.23
7-40-35
7. 46. 46
7.53. 8
8. i. 38
8. 8. 5o

4. 35 59

L
L
L
R
R
It

It

339.42.58-6
339.43. 2-8
339.43. 5-7
200. 1 5. 14-0
200. 1 5. 26- 1
200. i5. 33-9

202. 10. 1*3

71-8
72-0
71-9
74-5
74-0
73-2

70-8

i5o-i
i5o- 1
i5o- 1
i5o~o
i5o-o
149-9

i36-6

4. 40. jo

R

202. 8. 5o- 1

70-2

i36-8

J,

337. 5o. 55-6

69-2

i37'i

337. 52. 14-8

70-6

i37'3

« Ursse Minoris S.P. . . .
, , ...

» » • - •
o Columbffi

4. 56. 35
5. o. 59
5. 6. i5
5. 10. 56
5 24 38

L
L
It
It

346. 23. 27-8

346. 23. 21-2

193. 35. 11-9
193.35.42-3

71-7
71-8
72-2
7i-5
74 '4

227-9
227-9
227-9
227-9
81-6

TABLE VIII. — OBSERVATIONS FOR CO-LATITUDE (continued).

133

Barometer
and
External
Thermometer.

Zenith Point for
Center Wire, including
Zero of Level.

Concluded /enith
Distance.

Reduction to
Meridian.

Tabular
Apparent N. P. D.
of Star.

Colatitude.

Observed.

Adopted.

° /

o /

270. o

270. o

//

//

o / //

/ //

o / //

0 / //

24' 6

57. 10. 46-7

3.5i-6

125.48. 59-5

68.42. 4-4

24-0

> s

72. 5. 45 'o

o. 4-9

3. 23.46-0

42. 3-9

» •

72. 5.47-3

O. O'2

, ,

42. i-5

zS-i

» >

72. 5.45-1

o. 3-5

> j

42. 2-6

,,

72. 5.36-5

O. 12- I

» >

42. 2-6

3o'B- 1 1

23-4

» >

65.56. 16-7

O. I *O

1.45.45-4

42. i • i

58°- 8

"

65.56. 18-9

o. 0-7

f >

42. 3-6

i6-3

—

.8-7

—

69°-o

1 f

23-1

68. i3. 2-2

I. 21. 5-1

41. 55"2

1 J

» >

68. 1 5. 9'3

42. 5-i

r 21 • i <

\ }

>.

68. 16. 49- o

, ,

42. 5-2

J l

•,

68. 18. 22-4

> »

42. 2-9

21-8

» )

72. 5.55-3

o. 0-7

3.23.52-3

42. 3-7

) »

72. 5. Si -i

o. 2-3

J J

42. i • i

25-4

,,

73. 55.40-0

O. 2'I

I42.37.43'5

42. 5-6

•

, ,

73. 56. 22- 1

o. 39-6

, ,

42. I'D

23-4

J >

65. 56.31-3

o. 6-2

2.45. 39'I

42. 4'2

) >

65.56.24-8

O. I'D

» J

42. 2'9

23-2

1 $

65.56.25-9

o. 1-8

> J

42. 3-2

69° -o

J >

65.56.33-5

o. 7-9

9 t

42. 4-7

22 -O

> 1

69.46. 17-4

o. 4-0

I. 4. 19*6

42. 1-8

J »

69. 46. 21 -8

o. 1-4

) >

42. 3-6

24-2

) »

69. 46. 24-6

o. o-o

? >

42. 5-o

) »

69.46. 24-6

o. i-5

5 »

42. 6-5

3oin-i5

22-3

J >

69. 46. i3po

o. 8-0

> )

42. 1-4

69° -7

"

69.46. 5-9

o. 17-7

J t

42. 4-0

65° -7

1 (

23-1

67. 5i.z6-6

....

1.21. 5-3

42. 1-6

2,3

J »

67.52.39-6

—

3 »

42. 4-3

1 \

» »

67.53. 58-8

) >

42. i • i

J I

» »

67.55. 19-6

> >

42. 1-6

24-4

» >

76.28. 4-3

o. o-3

7.46. 1-9

42. 2-7

> >

76.27.57-8

o. 2-8

) >

41.58-7

20 '6

> »

76. 27.46-9

o. 18-8

> J

42. 3-8

> »

76.27. 17-2

o. 44- 8

I »

42. o-i

21-7

» »

55. 29. 12-3

2.42-4

124. 8.34-5

68.42. 4-6

s 2

134

TRANSIT OF VENUS, 1874. HONOLULU.

Day.

Observer.

Star.

Time by
Altazimuth-
Clock.

s
I

'"•?

J*

Circle-Eeading
corrected for
Runs of
Micrometers.

Level
Indication
(additive).

Refraction
(additive
when
Lamp L).

i875.

NI

a ( '<>] innh;?'

h m s
5. 20. 7

Ei

3z5. 25. 3-4

74-3

//
8i-5

5. 36. i3

R

414. 33. 54-2

8i-5

5. 41. ii

R

214. 3z. 27-8

7O' 2

81-6

S Ursae Minoris S.P. . . .
» > ...
» j ...
> »

5.53. Si
5. 58. 24
6. 5. 7
6. 9. 33
6. 15.46

L
L
R
R
L

342. 1.38-4
342. 1.54-8
197. 56. 13-9
197.56. 7-7
343. Si. 58-2

71-8
72-0

73-o
72-0
72-8

171-8
171-9
171-9
171-9

6. 20. 35

L

343. Si. 36'5

6. z5. 3i

R

6. 2Q. 4.Q

R

196. 4. 55-2

70*8

3o

NI

K

175.43. 53-9

7O'O

L

4. 14. 27 -6

72* o

L

4. 14. 25-8

73-0

R

175.43. 55-5

70* 6

Canopus. . . /

6. 1 6. 19

R

196. 6. 28-0

60* 7

loi - 6

6. 21. 29

R

196. 6.42-3

60-8

191*5

6. 27. AO

L

343. 52.46-8

73-8

IQI • 7

6. 3z. 53

L

343. 54. 41 • i

74 '7

192-8

3i

T

R

175. 44.48-0

71-5

R

175.44.47-8

71-8

B

175.44-48-5

71-9

L

4. i3. 3i'9

70-8

L

4. i3. 32-6

70-9

6. 40. 10

R

232. 9. 3-6

70-6

43-6

6. 46. 39

L

307. 52. 22-3

70-7

43'7

6. 53. 7

L

320. 4. II' I

74-0

67-0

6. 58. 24

E

219. 52. 58-i

7i-5

67-0

7. 5. 26

L

338. 37. iz-S

71-8

142-4

7. 8.41

L

338. 38. 19-7

71 -9

142-5

7. 14. 1 3

R

2OI. l8. O'2

72-4

142-7

7. 18 17

R

201. 16. 33-2

72-0

142-9

6. 16. zi

L

343.51.48-6

77-7

192-7

6. 22. 41

I,

343.51.43-1

77-8

192-7

6. 26. 56

R

196. 5. Si'9

68-z

192-8

*

6. 3i. 5i

R

iq6. 4. 7-6

67-2

193-4

Polaris ,

6. 5o. 4.2

338. 35. i3-5

68-4

143-2

7, 5. 14.

L

338. 37. 11-7

69-0

I43-S

TABLE VIII. — OBSERVATIONS FOR CO-LATITUDB (continued).

135

Barometer
and
External
Thermometer.

Zenith Point for
Center Wire, including
Zero of Level.

Concluded Zenith
Distance.

Seduction to
Meridian.

Tabular
Apparent N. P. D.
of Star.

Colatitude.

Observed.

Adopted.

o /

0 /

270. o

270. o

/,

it

0 , „

/ //

O / '/

o / //

23-1

55. 27. 16- 1

0.44-5

124. 8.34-5

68.42. 2-9

23-7

,,

55.26. 39-2

o. 8-8

,,

42. 4-1

63°-6

1 »

55.28. 6-7

i. 34-0

,,

42. 1-8

22 -O

,,

72. 5.18-9

o. 34-4

3.23.52-6

42. 0-7

,1

72. 5.35-6

o. 1 8 • 8

J *

42. 1-8

24-1

,,

72. 5.48-1

o. 4-3

J J

41. 59-8

II

72. 5.55-3

o. o-3

,,

42. 3-o

22-2

J 1

73. 56. 0-2

o. 2 1 • 7

142. 37. 43*8

42. 5-3

J f

73. 55. 40-2

o. o-3

,,

42. 3-9

3oln-ii

22'7

j y

7 3. 56. 14-6

o. 34-0

,,

42. 3-2

63°'4

"

73. 57.29-6

1.49-3

I »

42. 3-5

2f7

—

I

22'4

—

3oin-n

20-9

21-6

73.55.55-5

o. 16-4

142.37.44-0

42. 4-9

65°- 3

,.

73. 55.4I-0

O. 2-2

,,

42. 5-2

23-0

,,

73. 56. 5o-7

I. 9'2

» 9

42. 2-5

64° -2

* >

73. 58.47-0

3. 9-3

J t

42. 6-3

21- I

—

21-9

—

•

3oin-i5

23-o

22-6

37. 5o. 52-0

o. 7-7

1 06. 32. 46-6

42. 2 ' 2

65°-6

,,

37.53.54-1

3. 9-0

> J

42. i • S

22-3

f j

So. 6. 9-5

o. o-5

118.48. 12-6

42. 3-6

> J

5o. 7. 20-0

i. i"o'4

,,

42. 3-o

1 c

20 -6

68. 40. 26- 1

i. 21. 5-3

42. 4-6

[ 20.8 J

» »

68.41. 33-5

,,

42. 3-i

3oh'-i5

[I

i »

68.43. 3o-7

,,

42. 2-8

66° -o

J I

"

68.44. 58-3

"

42. 4-2

22'7

24-3

73.55.54-7

o.i5-8

142. 37.44-5

42. 5-6

,,

73.55-49-3

o. 8-0

,,

42. 3-2

23-8

,,

73.56. 37-0

0.54-7

,,

42. 2 • 2

63°-2

,,

73.58.22-9

2.40-8

,,

42. 2-4

24-3

,,

68. 38.20-8

i. 21. 5-3

42. o-5

"

68.40. 19-9

• « . •

"

68.42. 2-1

136

TRANSIT OF VENUS, 1874. HONOLULU.

Bay.

Observer.

Star.

Time by
Altazimuth-
Clock.

K

•1

3

^

|H!

Circle-Heading
corrected for
Runs of
Micrometers.

Level
Indication
(additive).

Kefraction
(additive
when
Lamp L).

1875.
February i

HI

Polaris

h in s
7. II. l6

R

20 1. 19. 61 8

74-4

143-8

7. 1 8. 40

R

20 1. 1 6. 3z • 2

74' °

142-2

K> Cephei S P

7. 58. AO

K

188.44. 3-2

73-2

35i-i

8. 3.40

It

188.43. i5-5

73-1

35i-6

8. 12. 22

L

35i. i5. 37-9

68-3

35l-q

8. 18. 53

£,

35i. i5. 16-2

68-4

35i'7

NI

6. 6. 26

L

3o2. ii. 56* 9

64-2

35-5

6. i3. 14

R

237. 46. 46*0

77-6

35-5

6. 25. 42

L

307. 56.47-6

81-4

4*1 ' °

6. 3o. 22

L

307. 52. ii -o

80-8

43-9

6. 38. 3o

K

2 3 2. 9. 19 '4

64-1

43-8

6.43. 56

R

23z. 7. 55' 8

64*0

43-8

u

234. 48. 3o-2

63-i

3o-8

6. 59. 21

L

3o5. 14. 36-6

78-8

Sg^

5

8. 32. o

L

33g. 7.i5-3

67 ' Q

147 " 5

8. 38. 4

B

200. 49. 8 ' 2

80 'I

147- 7

8 5i 23

K

80-6

29' 2

8 56 AO

L

65-0

2Q * 2

o. 6. 36

R

190. o. 55*8

65-2

3oo-5

9. 10. 36

R

IQO. I. "2.6'A

65-2

3oo-3

9. 1 6. 1 5

Ii

349.57. o-5

79'°

309-4

L

349. $7. 44 • 5

70-8

3oQ'7

/

TABLE VIII. — OBSERVATIONS FOR CO-LATITUDE (coiichuled').

137

Barometer

Zenith Point for
Center Wire, including

Tabular

and
External

Zero of Level.

Concluded Zenith
Distance.

Reduction to
Meridian.

Apparent N. P. D.
of Star.

Colatitude.

j

'hermometer.

Observed.

Adopted.

270. o

270. o

//

,/

0 / //

/ //

O / //

0 , /,

24-7

24-3

68. 42. 26-9

....

i. 21. 5-3

68.41. 1-2

3o'"-i5

> >

68.45. 3-3

....

> >

42. O'S

6»*-i

26 'o

J '

81. 20. Sg 'o

i. 9-9

1 2. 40. 8 • 4

42. O'S

>,

81. 21.47-3

0.25-8

, ,

42. 4-7

24' 7

> )

81.22. i3-8

o. o- 1

j >

42. 5-5

» >

81. 21. 52-o

o. 20-4

j »

42. 4-0

64° -O

23-4

22-9

32. i3. i347

0.33-4

36.2g.23-8

42. 4-1

» »

32. 12. 54-8

o.i5-5

, ,

42. 3-i

23-2

» »

37.58. 3o-i

7.47-2

106. 32.47-0

42. 4-1

» J

37.53.52-8 3. 8-9

> >

42. 3'i

23-2

> *

37. 5o. 43-2

o-o

» »

42. 3-8

63° -3

, ,

37. 52. 6-9

I. 24*6

» >

42. 4-7

3o>"-i3

21-7

; '

35. ii. 29-4

o. 29-2

io3. 53. 0-2

42. o-o

63'-i

..

35. 16.12-4

5. 14-6

> t

42. 2-4

59°-i

25-5

25-6

69. 10. z5- 1 .

i. ii. 5-7

42. 1-4

,,

69. 12. 25-0

....

j »

42. i • 6

2!'4

21-6

27. 14. 6'5

o. 9-4

41. 28. 7- 1

42. 4-2

, ,

27. 16. 18-7

2. 2 1 • 9

» >

42. 3-9

23-5

, ,

80. 3.3o-i

o. 34- 5

148.45. 0-4

42. 4-8

3o'n-oo

, ,

80. 2.59-3

o. 3-8

» >

42. 4-9

21'2

, ,

80. 3. 7'3

o. 12-9

> >

42. 6-0

58°-o

* J

80. 3.52-4

o. 52-9

? »

68.42. 0-9

138

TRANSIT OF VENUS, 1874. HONOLULU.

TABLE IX. — VERTICAL TRANSITS of the MOON and of STARS near the MOON

Day.

Observer.

1

Object.

Altazimuth-
Clock Time
of Vertical
Transit over
Mean of
Horizontal
Wires.

Lamp Right or Left.

Reading of
Vertical
Circle
corrected for
Runs of
Micrometers.

Level Indication (ad-
ditive).

Barometer and Ex-
ternal Thermometer.

|

True observed
Zenith
Distance.

1874.
October 3

T

li m »

5. i5. 3-38

R

i.

222. O. 28-9

3i5.43. 32-6

66-0
76-2

3oin-22
7I°-5

//

62 'o
57-3

0 / //

48. 0.22-7
45. 44. So -5

, , ...

5.25. 17-52

> > ...

5. 34. 17-60

L

3i3.44. 8-7

75-4

53-5

43.45.22-0

» > • • •

5.42. 24-96

L

3ii. 56. 12-6

74-6

So-2

41. 57. 21 '8

» » ...

5. So. 1-96

•

229.44. 5o'9

62-4

47-3

40. 15.49-6

> » • • •

5. S?. 22-04

6. 6. iS'oo
6. 16. 22-80

K

•
L

23i. 22.40- 1

»I2. 37. 3-6

325. 3.37-1

62-6

62-1

75-4

7i°-o

44'7

87-2
79-9

38.37.57-6
57.24. 17-1

55. 5.16-8

4

NI

Moon's L. L. ...

5. 3o. 53-6o

L

326.50.48-3

75-o

85-3

56.52. 3i-7

,,

5.4i-33-3o

L

324.28. 15-4

75-4

78-0

54. 29. Si -9

, y ...

5.52. 9-68

K

217.53.37-5

66-0

71-6

Si. 7.25-0

J , ...

6. 2.33-20

K

220. I 3. 22 ' 6

65-8

72° -7

65-9

49.47.34-4

it • • *

6.39. 6-88

L

3n. 32. 14-4

73-9

3oln-23

49 '4

41. 33. 20-8

5

NI

J ) ...

Regulus

6.46.59-94

4. So. 17-82
5. 4.56-80
5. 18. 10-52

•

R
L
L

z3o. 14. 19-9

195. 52. 29-9
340.44. 19-0
341.48.23-2

66-5

59-6
8i-5
81-2

73°-o
72° -o

46-4

193-2
i58-i
167-9

39.46. 16-9

74. 10. 40-6
70.47.21-7
71. Si. 35-4

Moon's L. L. ...

» > ...

5.26. 12-98

L

340. i. 4-9

82-1

l52"I

70. 4. 2-2

> t • • •

5. 34.22-66

L

338. ii. 50-9

81-2

i38-6

68.I4.33-8

o / //

October 3. The adopted Zenith point corresponding to the mean wire is 270. o. 55-6
October 4. „ „ „ 270. o. 56 '9
Octobers. „ „ „ 270.0.56-9

TABLE IX. — LONGITUDE FROM MOON'S OBSERVED ZENITH DISTANCE.

139

observed with the ALTAZIMUTH, and Inferred LONGITUDE of HONOLULU.

Greenwich Mean
Solar Time,
assuming the West
Longitude to be
I. ioh. 3 11". os.

II. I0h. 32m. 0s.

Tabular Geocentric Elements
(R. A. and N. P. D. corrected).

Hour-Angle.

Tabular Zenith
Distance of
Star or
of Limb of
Moon.

Inferred
Longitude
West of
Greenwich
icf1. 3im. +

Apparent
Right
Ascension
of Center.

Apparent
North Polar
Distance
of Center.

Equatorial
Horizontal
Parallax.

Semi-
diameter.

h in s

h 1,1 .

0 / //

f H

/ //

0 / //

0 / //

I. 2.52.52-58

8.38. 5g-85

66. 10. i-5

56. 5-2

i5. i8-5

Si. 9.20-55

48. o. 1 3 • 8

II. 2.53.52-41

8. 39. 2-07

66. 10. 10-0

56. 5-2

i5. i8-5

5i. 9.53-85

48. 0.45-1

17-1

I. 3. 3. 5-3o

8. 39.22-57

66. ii. 29-0

56. 4-9

i5. 18-4

48.41. 25 -So

45.44.38-9

II. 3. 4. 5 '14

8. 39.24-79

66. ii. 37-5

56. 4-9

i5. 18-4

48.41. 58- 80

45. 45. 10-4

22' I

I. 3. 12. 4-12

8. 39.42-54

66. 12. 46-0

56. 4-6

i5. 18-4

46. 3 1. 20-25

43.45. 9-4

II. 3. i3. 3-96

8.39.44-76

66. 12. 54-6

56. 4-6

i5. 18-4

46.3I.53-55

43. 45. 40-6

24-2

I. 3. 20. 10-35

8. 40. o- 56

66. iS.55'7

56. 4-6

i5. i8-3

44.33.57-45

41.57. 8-8

II. 3. 21. 10-19

8.40. 2-76

66. 14. 4-2

56. 4-6

i5.i8-3

44. 34. 3o-45

41.57.39-8

25-2

I. 3.27.46-30

8.40. 17-44

66.i5. i'i

56. 4-2

i5. 18-2

42.43.52-65

40. 15.41-7

II. 3.28.46-14

8. 40. 19-65

66. i5. 9-7

56. 4-2

i5. 18-2

42. 44. 25 • 80

40. 16. 12-7

i5-3

I. 3.35. 5-35

8.40. 33-69

66. 16. 4-3

56. 4-0

i5. 18-2

40. 57. 52-65

38. 37.52-2

II. 3.36. 5-i8

8. 40. 35-90

66. 16. 12-8

56. 4-0

i5.i8-2

40. 58. 25 -So

38.38.23-4

10-4

10. i3. 2-5o

69. 3i. 22-9

—

—

61. 5i. 46-95

57. 24.22-5

—

"

» 3

—

—

5g. 19. 46-20

55. 5.21-3

—

I. 3. 5.21-22

9. 3o. 53 -3o

70. 6.49-3

55. 29-2

i5. 8-7

60. o. 53-70

56. 52. 19-4

II. 3. 6.2i-o5

9. 3o.55-35

70. 7. 0-2

55. 29-2

i5. 8-7

60. 1.24-45

56. 52. 5o-i

24-0

I. 3.15.59-41

9. 3i. i5-25

70. 8.45-3

55.29-1

i5. 8-7

57-26.23-85

54. 29. 37-0

II. 3.I6.59-25

9. 3i. 17-31

70. 8.56-1

55. 29-1

i5. 8-7

57.26.54-75

54.3o. 7-8

29-0

I. 3.26.34-32

9.31.37-07

70. 10.40-7

55.28-8

i5. 8-6

54. 52.41-40

52. 7.i5'5

II. 3.27.34-16

9. 3i. 39'i3

70. 10. 5i-6

55.28-8

i5. 8-6

54.53.i2-3o

52, 7.46-2

18-6

I. 3.36.56-38

9.31.58-45

70. 12. 33-8

55.28-6

i5. 8-6

5i. 22. 5 • 70

49.47.26-5

II. 3. 37. 56-22

9. 32. o-5i

70. 12.44-8

55.28-6

i5. 8-6

52. 12. 36 -60

49-47-57-1

i5-5

I. 4. i3. 24-95

9. 33.13-56

70. 19. 13-4

55.27-7

i5. 8-3

43. 32. i3-8o

41.33. 7-2

II. 4.14.24-79

9.33. i5-6i

70. 19.24-4

55.27-7

i5. 8-3

43. 32.44-55

4i.33.37-7

26-7

I. 4. 21. l6'92

9. 33.29-74

70. 20. 39-9

55.27-5

i5. 8-2

41.37.57-75

39.46. 5-6

II. 4. 22. l6'75

9.33.3i-8o

70. 20. So -8

55.27-5

i5. 8-2

41. 38.28-65

39.46. 35-9

23-1

10. 1.40-67

77-25. 5-5

—

—

77.42.48-45

74. 10.45-1

—

,,

> )

—

—

74. 2. 58 -o5

70.47.17-8

—

I. 2. 49. 20-41

10. 18. 14-08

74.45.3i-5

55. o-o

i5. 0-7

74. 52.48-60

71. 5i. 15-9

II. 2. 5o. 2O-25

10. 1 8. 16-00

74.45.43-9

55. o-o

i5. 0-7

74.53.17-40

71. 51.46-1

38-7

I. 2. 57. 21 -76

10. 18. 29-56

74. 47. 1 1 • 7

54.59-8

i5. 0-7

72.56. 0-90

70. 3.44-4

II. 2.58.21-60

10. 18. 3i -49

74.47.24-2

54.59-8

i5. 0-7

72. 56. 29-85

70. 4.14-8

35-1

I. 3. 5. 3o-3o

10. 1 8. 45-27

74.48.53-5

54.59-8

i5. 0-6

70.57.28-35

68. 14. n-6

II. 3. 6.30-14

10. 1 8. 47-20

74.49. 6-0

54. 59-8

i5. 0-6

70. 57. 57'3o

68. 14. Si*9

24-2

140

TRANSIT OF VENUS, 1874. HONOLULU.

Day.

i

Object.

Altazimuth-
Clock Time
of Vertical
Transit over J
Mean of jg
Horizontal
Wires.

Heading of
Vertical
Circle
corrected for
Huns of
Micrometers.

.1 "£ °

1* 15
"Si U

; True observed
Zenith
Distance.
KS

0

3

1> n -t-

1874.

h ,., i

0 / //

„

ft 0 / //

October 5

NI

Moon's L. L. ...

5.47. 17-02

u

204. 40. ^q • 6

64-0 .

120-9 65. 21. 4-2

5.56.44-18

r. 206.47.58-7 62-2 3o'n-i6

uo- 1 63. i3. 46-1

|

„

6. 5.3o-22

R

208. 46. i5'o

61 -4

7I°-2

101 -3

61. i5. 21-8

7

T

Resruius ...

6. 7.58-84

R

214. 5. 39-4

56-8

82-0

55. 55.43-1

/

6. 17. 34-34

L

323. 39. 55-4

86-0

67° -6

ttm y

76-3

53.41. 39-3

Moon's L. L. ...

6. 27. 1 3- 16

I,

35o. 5.32-3

86-5

310-4

8c. ii. io-5

,,

6.33. 32-6o

K

191. 18. 57-9

55-5

273-0

78. 45. 3S-o

,,

6.38. 39-04

R

192. 27. 40-2

55-6

248-4

77. 36. 3i -o

'

> ) ...

6.44. 3-12

L

346. 19. 1 1/4

87-4

226-6

76.23.27-0

,,

6. 50.43-02

L

344.49.24-8 87-2

3o">-i4

204-1

74.53. 17-7

1 ) • • •

6. 56.28-96

R

196. 28. 0-7

54-8

67° -6

187-6

73. 35. lo-S

'

T

Moon's L. L.

21. 5i. 1 1 - 3o

X

348. 42. 59-6

61*0

74° -6

270-2 78. i8. 8-5

21. 58. 14-50

R

189. 59. 23'o

79-1

3o"" 1 5

3o3-o

/ 1

80. 4.43-2

"

22. 6.54-74

R

188.25. 6-2

78-0

355-7 • 8i.39.53-8

,,

22.16. 8-32

I.

353. 14. 24-9

59-4

435-o

83. 22. 17-0

o" Saffittarii . .

22. 28. 47 - 52

341. 48. 55'7

62-2

75°-o

167-3

71. 52. 2" ' 0

22. 36. 42-26

R

196. 43. 14-4

77-8

182-1

/ . _ j

73. 18. 52-2

17

NI

Moon's L. L. . . .

23.45. 25-28

R

192. 22. 42-4

72-4

!

246-6

77-40- 34' i

,,

o. 7.41-64

L

35i. 38.41-9

65-7

3oh'-i5

359-7

8i.45. 25-o

, ,

o. i5. 23-82

U

186. 54. 34-3

72-4

74° -o

425-5

83. 11.41-1

1

0 / //

October 7. The adopted Zenith point corresponding to the mean wire is 270.0.58-4.

October 1 5. „ „ „ 270.0.22-3.

October 17. „ „ ,, 270.0.21-3.

TABLE IX. — LONGITUDE PROM MOON'S OBSERVED ZENITH DISTANCE (continued}. 141

Greenwich Mean
Solar Time,
assuming the West
Longitude to be

I. iok. 3 im. o>.
II. lo1'. 32'". oS

Tabular Geocentric Elements
(R. A. and N. P. D. corrected).

Hour-Angle.

Tabular Zenith
Distance of
Star or
of Limb of
Moon.

Inferred
Longitude
West of
Greenwich
ioh. 3im. +

Apparent
Right

Ascension
of Center.

Apparent
North Polar
Distance
of Center.

Equatorial
Horizontal
Parallax.

Scmi-
diameter.

li m s

h :u s ° / " 'II

1 II Oil!

0 / //

S

I. 3.i:?. 12-Sy

10. 19. 10- ii

74.51.34-7 54.59-6

i5. 0-6

67. So. 3o'6o

65.20. 55-0

IF. 3. 19. 22-7:

IO.I9.I2-O3 74.5l.47-2

54.59-6

i5. 0-6

67. 5o. 29-40

65.21.25-2

iS-3

I. 3.27.48-73

10.19.28-29 74.53.32-8

54. 59-4

1 5. o-5

65. 32.42-15

63. 1 3. 32-3

II. 3.28.48-57

10. 19. 30'22 74. 53.45-3

54-59-4

1 5. o-5

65.33. n-io

63. 14. 2-7

27-2

I. 3.36.33-54

10. 19. 45-i5

74. 55.22-4

54.59-2

i5. o-5

63.25.21-45

61. i5. 10-2

II. 3. 37.33--7

10. 19.47-07 74. 55. 34-9

54. 59-2

i5. o-5

63.25.20-25

61. 1 5. 40-4

23-0

10. 1.40-73 77-25. 5-7

—

58. 3.27-00

55.55.44-7

—

I. 3. 5i. 16-02

II. 3.52.i5-86

ii. 48. 14-84
1 1. 48. 16-60

35.44. 58'9
85. 45. 12-9

54. lS'2
54. lS'2

55.39.3o-75
14. 49-3 79. 53. i6-65
14.49-3 79.53.43-0$

53.41. 39-0
So. 10. 57-2
80. ii. 26-9

27-5

I. 3.57.34-60

ii. 48. 26-00

85. 46. 27-6

54. 18-1

14. 49'3 78- 21. 9-90

78.45.24-7

II. 3. 58. 34-43

11.48.27-76 j 85.46.41-6

54. :8-i

14. 49-3 78. 21. 36- 3o

78.45.54-4

26-9

I. 4. 2.40-32

11.48. 35-oo 85.47. 39'i

54. 18-0

14.49-3 77- 6.46-50

77. 36. 18-4

II. 4. 3.40-15

11.48. 36-77

85.47- 53-i

54. 18-0

14.49-3

77. 7-i3-o5

77. 36.48-1

25-4

I. 4. 8. 3-64

ii. 48. 44-53

85.48. 54-8

54. 18-0

14.49-2

75.48. 6-3o

76.23. 12-6

II. 4. 9. 3-48

ii. 48. 46-29

85.49. 8'8

54. 1 8-0

14. 49-2 75.48. 32-70

76. 23.42-2

29-2

I. 4. 14. 42-61
II. 4. 15.42-45

ii. 48. 56-29
11.48. 58-o5

85. So. 28-3
85. So. 42-3

54. 17-9
54. 17-9

14. 49-2 74. ii. i-65

14. 49-2 '•• 74. n. 28-o5

74. 53. o-o
74. 53.29-5

36-o

I. 4.20.27-74

11.49. 6-45

85. 5i.49- 1

54.17-8

14.49-2 71-47- 3-oo

73.34.57-5

II. 4.21.27-58

11.49. 8-22

85.52. 3-i

54.17-8

14.49-2

72. 47. 28-20

73. 35. 26-0

27-4

[. 1 8. 44. i5'5o

17.43. 4-04

117. 58.28-6

55. 7'5

1 5. 2-8

62. 9. 56- 10

78.48. 20-7

II. i8.45.i5-33

17.43. 6-33

117. 58. 30-9

55. 7'5

i5. 2-8

62. 9.21-75

78.47. 56-3

3i-9

I. 18.51.17-55

17. 43. 20-24

117. 58.44-9

55. 7-7

i5. 2-8

63. 5i. 41 -25

80. 4.54-6

II. 18.52.17-39

17. 43. 22-54

117. 58. 47-2

55. 7-7

i5. 2-8

63. 5i. 6- 75

80. 4.29-8

27-6

I. 18.59. 56-38

17.43.40-18 117.59. 4-9

55. 7'9

i5. 2-9

65. 56.46-05

81.40. 2-9

II. 19. o. 56-22

17. 43. 4*'43

117.59. 7-2

55. 7'9

1 5. 2-9

65.56.11-55

81. 39. 37-8

21-7

I. 19. 9. 8-49

17.44. I '40

117. 59. 25-9

55. 8-1

i5. 2~9

68. 9. Si-go

83. 22. 26-2

II. 19.10. 8-33

17.44. 3-7o

117. Sg. 28-2

55. 8-1

1 5. 2-9

68. 9. 17-40

83.22. 0-7

21-6

18.47. 29-15

1 16. 27. io'5

—

—

55. 27. 44-10

71. 52. 25'6

—

"

••

—

—

57.26.25-5o

73. 18. 53-8

' • -

I. 20. 3o. 28-27

19. 40. 17-60

116.49. 5'9

56. 32-7

i5. 26-0

61. 27. 22-65

77.40.41-5

II. 20.31.28-10

19. 40. 19-66

116.49. °'7

56. 32-7

i5. 26-0

61. 26. 47-2$

77.40.12-1 i5-i

I. 20. 52. 41-06

19. 41. io-23

116.47. 9'2

56. 33-5

15.26-2

66. 48. 19-95

81.45. 26-5

II. 20. 53. 40-90

19. 41. 12-60

116.47. 3-9

56.33-5

15.26-2

66.47.44-40 81.44.56-3

3-o

I. 21. O. 22'OI

19. 41. 28-44

1 1 6. 46. 28-6

56.33-7

15.26-3

68. 39. 19-9$ 83. ii. 44-3

II. 21. I. 21-85

19.41.30-80 116.46.23*3

56. 33-7

iS.26-3 68.38.44-55 83. n. 14-0 ! 6-3

T 2

142

TRANSIT OF VENUS, 1874. HONOLULU.

Day.

i

o

Object.

Altazimuth-
Clock Time
of Vertical
Transit over
Mean of
Horizontal
Wires.

1

b

o

I

«i

Reading of
Vertical
Circle
corrected for
Runs of
Micrometers.

Level Indication (ad-
ditive).

Barometer and Ex-
ternal Thermometer.

Refraction.

True observed
Zenith
Distance.

1874.
October 18

T

Moon's L. L. ...

o. So. 17-50

R

0 / //

192.45. 36-5

n

77-6

240-2

o / //

77. 17. 28-4

, ,

0.58.33-98

R

191. 12.40-8

75'3

272-6

78. So. 58-8

,,

i. 4. i3-54

L

349. 49. 47 • 9

63-6

3oo'2

79. 55.29-4

,,

i. i3. 18-62

I,

35i.33. 19-2

64-4

357'5

Si. 39. 58-8

'

,,

1.19. 5-28

L

352. 39. 29-2

64-8

406" i

82.46.57-8

XI

1.25. 5-34

1.33. 7-76
i. 41. 17-16

O. O. l8"22

K

R
L

L

186. 10. 0-4

190.53. 35-2
35o. 3o. 15-7

325. 54.40-8

76-0

72-5
66-8

64-0

,-0. 0

/2 X

471-6

28o-3
320-4

81-9

83.56.57-5

79. 10. 14-9
80. 36. 20-6

55. 56. 44-4

& Grois

Moon's L. L. ...

,

o. 9.25-56

R

212. 37. 34-6

75'3

86-4

57.22.58-8

,,

o. 17. 39-56

L

328.40.56-5

62-8

91-0

58.43. 8-0

,,

o. 25. 26-08

R

2IO. O. 2'8

76-8

95-7

60. o. 38-4

. ,

3 3 - • »

o. 34. 52-34

L

33i. 34. 38-6

63-6

IO2'2

61.37. 2-1

Fomalhant

0.43. 4-32

o. 53. 59-84
i. 4. 12-16

R

R
L

206. 58. 19-3

2IO. 25. 21 'I

330.48.53-9

76-4

73-6
65-3

3o'"-i9
75°-o

io8-5

94-1
99-1

63. 2.35-1

59.35.2i-8
60. Si. i5'9

21

BJ

Moon's L. L. ...

I. 34. 21-92

L

314. 47. 38-o

61-2

73°-i

55-4

44.49. 12-3

,,

I. 43. 17-60

L

3i6. 23. 27-7

61-2

3oln-i7

58-6

46.25. 5-2

,,

I. 54.25-98

L

3i8. i5. 20-6

61-2

62-6

48. 17. 2-1

j » ...

2. 2. 5'6o

L

319.41.40-7

61-1

65-8

49. 43. 25-3

0 / //

October 18. The adopted Zenith point corresponding to the mean wire is 270. o. 22-3.
October 19. „ „ „ 270.0.22-3.
October 21. „ „ „ 270.0.22-3.

TABLE IX. — LONGITUDE FROM MOON'S OBSERVED ZENITH DISTANCE (contiiwed). 143

Greenwich Mean
Solar Time,
assuming the We",t
Longitude to be
I. ioh. 3im. o".

II. I01'. 32m. 0s.

Taoular Geocentric Elements
(R. A. and N. P. D. corrected).

Hour- Angle.

Tabular Zenith
Distance of
Star or
of Limb of
Moon.

Inferred
Longitude
West of
Greenwich
ioh. 3lm. +

Apparent
Right
Ascension
of Center.

Apparent
North Polar
Distance
of Center.

Equatorial
Horizontal
Parallax.

Semi-
diameter.

h ui >

o / //

/ //

/ //

o

O .' If

9

I. 21. 3i. 19-94

20.39. 9'°7

n3. 5i. 0-6

57.27-0

i5. 40-9

62.58.56-55

77.17.42-4

II. 21. 32. 19-27

20. 39. 11-40

n3. 5o.5i-6

57.27-0

15.40-9

62. 58.2i-6o

77. 17.10-4

26-2

I. 2I.39.34-59

20. 39. 28-?,9

113.49.46-4

57.27-4

15.40-9

64.58. i5'75

78.51. i3-8

II. 21.40. 34'42

20. 39. 30-62

113.49. 37'5

57.27-4

i5. 40-9

64. 57. 40-80

78. 50.41-7

28-0

I. 21.45. I3-24

20. 3g. 41 -45

113.48.55-7

57.27-6

15.41 -o

66. 19. 52-o5

79.55.45-I

II. 2I.46.I3-03

20.39.43-77

113.48.46-7

57-27-6

1 5. 41-0

66. 19. 17-25

79. 55. 12-9

29-3

I. 2I.54.I6-87

20.40. 2 -55

n3. 47. 34-0

57.27-9

15.41-1

68.3o.52-35

81.40. i3-o

II. 2I.55.l6-70

20.40. 4-87

1 1 3. 47. 25-0

57.27-9

1 5. 41 • i

68. 3o. 17-55

81. 39.40-7

26-4

I. 22. 0. 2-59

20. 40. 1 5 • 97

113.46.41-9

57.28-1

1 5. 41-2

69. 54. II -10

82. 47. 1 1 • 5

II. 22. I. 2-42

20. 40. 18-29

113.46. 32-9

57.28-1

15.41-2

69. 53. 36- 3o

82.46. 39-1

25-4

I. 22. 6. I'69

20. 40. 29-91

113.45.47-8

57.28-4

i5. 41-2

71. 20.43-20

83.57. i°-8

II. 22. 7. 1-52

20.40. 32-23
22. 35. 12- 13

113.45. 38-7
137. 32. 3o-2

57.28-4

i5. 41-2

71.20. 8-40
46.43. 8-10

83.56.38-4
80. 36. 25-2

24-6

—

'I. 20. 37. 36-92

21. 32. 20'5l

109. 46. 55'6

58.21-3

i5. 55-6

37. 12. 23-10

55. 56. 49-0

II. 20.38.36-75

21. 32. 22-'78

109. 46. 43-6

58.21-3

i5.55-6

37. 11.49-05

55.56. 18-2

9-0

I. 20. 46. 42 • 79

21. 32.4I-20

109.45. 5-5

58.21-6

i5. 55-7

39.24. 3-3o

57.23. 3-i

II. 20.47.42-63

21. 32. 43-46

104.44. 53-5

58.21-6

iS.55-7

3g. 23. 29-40

57. 22. 32'I

8-3

I. 20. 54. 55-47

21. 32. 59-86

109.43. 26-1

58. 22-0

15.55-8

41.12.53-85

58.43. ii -5

II. 20. 55. 55'3i

21. 33. 2-12

109.43. 14-0

58. 22-0

iS.55-8

41. 22. I9-95

58. 42. 40-0

6-7

I. 21. 2.40-75

21. 33. 17-48

109.41. 52-o

58.22-3

iS.55-9

43. 1 5. 7-80

60. o. 44- o

II. 21. 3.40-59

21. 33. 19-74

109. 41. 39-9

58.22-3

15.55-9

43. 14. 33-90

60. 0. 12-2

10-6

I. 21. 12. 5-5o

21.33.38-87

109. 39. 57-6

58.22-6

i5. 56-o

45. 3i.2i-3o

61.37. 6-5

II. 21. i3. 5-33

21. 33.4fl3

109. 39.45-5

58.22-6

i5. 56-o

45. 30.47-40

61.36.34-2

8-z

I. 21. 20. 16- 17

21. 33. 57-44

109. 38. 18-2

58.23-0

1 5. 56- 1

47.29.42-90

63. 2.42-5

II. 21.21. l6'00

21. 33. 59-70

109. 38. 6-0

58.23-0

iS.56-1

47.29. 9-00

63. 2. io-o

i3'7

22. So. 44*46

120. 17. i3-i

—

—

3i. i. 5i-oo

59. 35. 19-9

—

» j

» >

—

—

33.34. 56-25

60. Si. io-o

—

I. 22. 4.43*41

23. 22. 14-48

97. 39. 22- 5

60. i3-5

16.26-3

33.32.22-o5

44.49. 18-4

II. 22. 5.43-25

23. 22. 16-66

97.39. 5-7

60. i3-5

16.26-3

33.31.49-35

44.48.43-1

10-4

I. 22. I 3. 37-67

23.22.33-98

97.36.52-7

60. i3-8

16.26-3

35.4I.25-35

46. 25. 12-5

II. 22. 14. 37'5i

23. 22. 36-i6

97.36.35-9

60. i3-8

16.26-3

35.40.52-65

46. 24. 36-9

12-3

I. 22.23.44-44

23.22.56-13

97.34. 2-5

60. 14-2

16. 26-4

38. 7.59-55

48.17. 7-0

II. 22. 24. 44*28

23.22.58-31

97.33.45-7

60. 14-2

16. 26-4

38. 7.26-85

48. 16. 3i-i

8-2

I. 22.31.22-85

23.23. 12-85

97. 31.53-7

60. 14-4

16.26-5

39. 58. 43-65

49. 43. 33-o

II. 22.32.22-69

23. 23. 15-04

97. 3i. 37-0

60. 14-4

16.26-5

39. 58. io- 80

49.42. 56-8

2-8

144

TRANSIT OF VENUS, 1874. HONOLULU.

Day.

Observer.

Object.

f

Altazimuth-
Clock Time
of Vertical
Transit over
Mean of
Horizontal
Wires.

Lamp Bight or Left. 1

*

Heading of
Vertical
Circle
corrected for
linns of
Micrometers.

Level Indication (ad-
ditive).

Barometer and Ex-
ternal Thermometer.

Kefraction.

True observed
Zenith

Distance.

1874.
October 21

|

in

U m «

Moon's L. L. ... z. 1 1 . 49 • 02

L

321. 33. 22-0

ft

6!'2

70-3

- -
0 , „

5i.35.n-2

' '

2. 2O. 49'52

It

216. 39. 42-0

80-5

74'9

53.20. 34-7

• •

,,

2.29.47-84

R 214. 53. 8-4

80-6

79-9

55. 7.13-2

, , ...

2.47. 30-26

u

211. 18. 5o-5

80'6

91-4 j 58.41.42-6

22

NI

Moon's L. L. ...

3. 36. 53-94

i.

324. 3. 49' i

fl'4

73°-o

76-7

54. 5.54-9

> » • • •

3. Si. 22-92

L

327. 10. 41 -6

71-8

3o""i6

S6-i

57. 12 57-2

,, ... 4. i. 58-64

L

329. 28. 29-0

72-9

94-1

59. 3o. 53-7

... 4.28.19-68

•

204.44. 3-7

69-7

119-9

65. 17. 8-8

4.46.51-96

K

200. 39. 0-8

69-1

146-0

69. 22. 38 -4

23

T

Moon's L. L. ...

5. 8.52-8o
•?. TI. -n-78

It

L
L

195.46. 58-9

3o3. 24. 15-9
3o5. 3o. i5'3

68-8

69-6

70-2

75°-i
74° -o

i93-3

36-6
39-6

74. 1 5. 27-9

33. 25.40-8
35. 3I.43-8

, , ... 3. 21. 32-96

, , ...

3.27.59-68

L

3o6. 52. 3o-3

70-3

4''7

36. 54. i-o

i
» » • • •

3. 34. 17-80

L

3o8. i3. 27-8

70-2

'

43-8

38. 1 5. o-5

» » ...

3.41. 32-62

R

'

23o. ii. 12- 3

72-7

46-3 39.48.42-6

,,

3.48. 25-20

It

228. 41. 43-2

71-8

48-8

41. 18. i5' i

> » • • •

3.54. 34-16

It

_

227. 21. 2O'8

7i-3

5l"2

42. 38. 40*4

, , ...

4. 0.41-12

It

226. i. 3-o

70-9

53-6

43. Sg. i 'o

0 1 If

October 22. The adopted Zenith point corresponding to the mean wire is 270. o. 22-3.

October 23. „ „ „ 270.0.21-3.

TABLE IX. — LONGITUDE FROM MOON'S OBSERVED ZENITH DISTANCE (continued}. 145

Greenwich Menu
Solar Time,
assuming the West
Longitude to l>c
I. ioh. 3 11". c".

II. I01'. 32"'. 0s.

Tabular (Jeocentric Elements
(1>. A. and N. P. 1). corrected).

Tabular Zenith
Distance of
Hour-Angle. Star or
of Limb of
Moon.

Inferred
Longitude
West of

Greenwich
joh. 3i"'. +

Apparent
Right
Ascension
of Center.

Apparent
North 1'olar
Distance
of Center.

Equatorial „
Horizontal
Vnrallux. d'anu'ter-

ll in ; B

° / //

0 , „ . , „

j. 12.41. 4-71

23. 23. 34-09

97. 29. io-5

60. 14-7

16. 26-6 42. 19. 16-95

Si. 35.21-2

II. 22.42. A'55

23.23. 36-zS

97-28.53-7

60.14-7 16.26-6 42.18.44-10

5 1. 34.45-0

16-6

I. 22. 50. 3'77

23. 23. 53-77 i 97- 26- 39-0

60. 1 5"o 16.26-7 \ 44-29.29-70

53.20.48-5

II. 22. 5i. 3'6i

23.23.55-95

97. 26. 22-2

60. 1 5'o 16.26-7 44.28.57-00

53.20. 12-2

22-8

1. 22. 5l,. O'67

23.24. i3-36

97.24. 8-1

60. i5-3

16. 26-8

46. 39. 11-40

55. 7.26-8

]]. 23. o. o'5o

23.24. iS'55'

97. 23. 5i -3

60. i5-3

16.26-8

46. 38.38-55

55. 6.5o-4

22-4

1. 23. 16. 40-26

23.24.52-04 97. 19. io'o

60. 15-9 16.26-9 5o.55. 8-55

58.41. 58-8

II. 23. 17. 40-09

23. 24. 54-23

97. 18. 53-2

60.15-9 16.26-9 ; 50.54.35-70

58.41.22-3

26-6

1. O. 2. 4-69

o. 19. 12-41

90. 7. i5- 1 | 60. 57-9

16. 38-4 49. 42. 9-60

54. 5.59-6

11. o. 3. 4-52

o. 19. 14-61

90. 6. 57-3 ' 60. 57-9

16. 38-4 49. 41. 36-6o

54. 5.22-2

7-5

1. o. 16. 3i-34

o. 19. 44- 3 1

90. 2. 57-6

60. 58-2

16.38-5

53. n. 26-65

57. i3. 8-9

11. 0.17.31-18

o. 1 9. 46 • 5 1

90. 2. 39*8

60. 58-2

16.38-5 53.10.53-55

57. 12. 3i'4

18-7

1. 0.27. 5-34

o. 20. 7 -65 89.59.49-2

60.58-4 i6.38-6 55.44-32-55

Sg.Si. 7'9

11. 0.28. 5-i8

o. 20. 9 • 84

89.59.31-4 60.58-4 i6.38-6 | 55.43.59-70

59. 3o. 3o-7

22-9

1. 0.53.22-15

0.21. 5-7I

89.52. o-5

60.59-0 i 16.38-7 i 62. 5.i8-6o

65. 17. 20- 1

11. o. 54. 21-99

O. 21. 7-91

89. Si. 42-7

60. 59-0

16. 38-7 62. 4.45-60

65. 16.42-8

18-2

] . i . 1 1 . 5 1 • 46

O. 21. 46-56

89. 46. 3o'7

60. 59-4

16.38-9

66. 33. io-95

69. 22.49-3

11. i.i2.5i-3o

o. 21.48-77

89. 46. 12-9

60. 59-4

i6.38-9

66. 32. 37-80

69. 22. ii -8

'7-4

1. 1.33.48-76

0. 22. 35-10

89. 39. 59-0

60. 59-9

1 6. 39-0

71. Si. i6-5o

74. 15.42-1

11. 1.34.48-60

0. 22. 37'3o

89. 39. 41 • i

60. 5g"9

16. 39-0

71. 5o. 43 -5o

74. i5. 4-8

22-8

1. 23.32.57-29

1. II. 47-69

83. 8.17-8

61. 21-8

16.44-9

3o. 14. 25-95

33.25.55-i

II. 23.33.57-12

I. 11.49-96

83. 8. 0-2

61. 21-8

16.44-9

3o. 1 3. Si-go

33.z5. 17-1

22-6

1. 23.42.54-85

I. 12. IO"32

83. 5.22-3

61. 21 -9

1 6. 45-0

32. 38. 34-5o

35. 3i.58-o

II. 23.43.54-68

i. 12. 12-59 *1- 5. 4-8

61.11-9 16.45-0

32.38. 0-45

35. 3i.20-2

22-5

1. 23.49.20-53

I. 12. 24-93

83. 3.29-1

61.12-0 16.45-0

34. ii. 36-45

36.54. i3-4

II. 23. 5o. 20-37

I. 12. 27-20

S3. 3.H-6

61.22-0 16.45-0

34. 1 1 . 2-40

36.53. 35-5

19-6

1. 23.55.37-64

I. 12. 39-22

33. 1.38-5

6l. 22- 1

16.45-0 i 35.42. 34-20

38. i5. i3-8

11. 23.56.37-47

I. 12. 41 '48

83. i. 20-9

6l. 22- I

16.45-0 35.42. o-3o

38.i4. 36-3

;.i-3

1. o. 2. 5i -29

i. 12. 55-58

82. 59. 3i-o

6l. 22'I

16. 45-0

37. 27. 11-40

39.49. 1-4

11. o. 3.5i'i3

i. 12. 57-85

82.59. '3 '4

6l. 22- 1

16.45-0 37.26.37-35

39.48. 23-3

29-6

I. o. 9. 41-76

i. i3. ii • 17

82. 57.3o-3

6l. 5.2- 2

16. 45-0 39. 6. 26'55

41. 18. 32-8

I ] . o. i o. 42 • 60

i. i3. 13-44

82. 57. 12-7

61.22-2

16.45-0 39. 5. 52-5o

41. 17. 55-o

28-1

I. o. i5. 5o-73

i. i3. 25-i3

82. 55.42-3

61.22-3

16.45-0 : 40.35. n-85 ' 42.38.59-6

II. o. 16. 5o-57

i. i3. 27-39

82. 55.24-8

6l. 22-3

16. 45-0

40.34.37-95 42.38.21-7

3o'4

1. o. is. 56'7i

i. i3. 38-99

82. 53. 55-o

61.22-3

16.45-1 42. 3.28-65

43. 59. 19-8

II. 0.22.56-54

i. 13.41-27

82. 53.37-5

61.22-3

16.45-1 41. 2.54-45 43.58.41-7

29-6

146

TRANSIT OF VENUS, 1874. HONOLULU.

Day.

Observer.

Object.

Altazimuth-
Clock Time
of Vertical
Transit over
Mean of
Horizontal
Wires.

Lamp Kight or Left. 1

Beading of
Vertical
Circle
corrected for
Runs of
Micrometers.

Level Indication (ad-
ditive).

Barometer and Ex-
ternal Thurinometer.

Refraction.

True observed
Zenith
Distance.

1874.
October 2 3

T

j8 Andromedse . . .

ti in s

4. 10. 35 -3o

K

0 / //

226. 34. 54-3

ir

68-6

//
52-6

• . 0 / //

43. 25. I I'D

, ,

4. 17. 34-48

R

125. 9.20-6

67-9

55-3

44. 5o. 48 - 1

•

Moon's L. L. ...

4.39. 2-70

R

217. 32. 10-9

70-2

7*'3

52.28.12-5

, , ...

4.47.54-94

E

2i5.33. 43-6

7o-3

77-6

54. 26. 45-0

» » ...

4.57.37-66

L

326. 34.49-3

69-0

3o""i6

84-2

56.37. 1-2

, , ...

5. 10. 52-24

L

329. 3z. 18-0

69-8

72° -9

94'4

5g. 34.40-9

24

NI

Moon's L. L. ...

4- 7- 7-82

•

240. 33. 44-9

71-0

75°-5

3i-2

29.25. 56-6

, , ...

4. 18.46-16

K

237. 57. 57'6

71-0

34-6

32. 1.47-3

.

,,

4.37.35-72

R

233.44.57-3

7i'4

40-5

36. 14.53-1

,,

4.47.50-44

L

3o8. 31.41-7

67-6

44-1

38. 33. 12-j

5. 0.21-84

L

3 1 1 . 20. 40 • 7

69-0

48-7

41. 22. I7'I

25

T

5. 7.26-74

5. 1 8. 20- 14
5. 26. 17- 70

5. 8.41-56

L

t

R

R

312.56. 20-8

3o5. 50.44-3
235. So.42-3

241. 54. 17-4

69-4

72-6
69-4

71-2

3oin'I2

74° -8
73°-o

5i-5

40-0
37-6

29-6

42. 58. 0-4

35. 52. i5'6
34. 9. 7-2

28. 5.22-3

Moon's U. L. . . .

,,

5. 17. 28-24

R

23g. 55. 24-0

71-1

32-i

3o. 4. i8-3

,,

5.24. 13-74

R

238.23. 57-9

70-9

34-i

3i. 35.46-6

, , ...

5.37. 5-32

L

304. 28. 22 "I

69-4

So1'" 1 1

38-i

34. 29. 48- 3

» > • • •

5.45.49-86

b

3o6. 26. 21-4

70*0

73°'4

40-9

36. 27. Si-o

,,

6. 5.42-88

L

3io. 53.58-0

70-6

48-0

40.55.35-3

o / //

October 24. The adopted Zenith point corresponding to the mean wire is 270. o. 21 • 3.
October 25. „ ,, .. 270.0.21-3.

TABLE IX. — LONGITUDE FROM THE MOON'S OBSERVED ZENITH DISTANCE (continued). 147

Greenwich Mean
Solar Time,
assuming the West
Longitude to be
I. ioh. 3 1". os.

II. I0h. 32m. 0".

Tabular Geocentric Elements
(R. A. and N. P. D. corrected).

Hour-Angle.

Tabular Zenith
Distance of
Star or
of Limb of
Moon.

Inferred
Longitude
West of
Greenwich
ioh. 3im. -i-

Apparent
Right
Ascension
of Center.

Apparent
North Polar
Distance
of Center.

Equatorial
Horizontal
Parallax.

Semi-
diameter.

k m i

h m a

0

/ //

/ //

0 / //

o / //

s

I. 2.44-19

55. 2.28-9

—

—

47.15.43-65

43. 25. 12- I

—

, ,

,,

—

—

49. o. 3i-8o

44.50.47-6

—

I. I. O. 12- 12

i. i5. 6-08

82. 42. 42- 5

61. 22-7

16.45-2

5i. 17. 7-65

52.28.27-2

II. I. I. II "93

i. i5. 8-35

82. 42. 24-9

61. 22-7

1 6. 45-2

5i. i6.33-6o

52.27.49-5

23-4

I. I. 9. 2'92

i. i5. 26-23

82.40. 7-1

61. 22-8

16. 45-2

53.25. 9'3o

54.27. 4'3

II. i. 10. 2-76

i. i5. z8-5o

82. 39.49-6

61. 22-8

16.45-2

53.24.35-25

54.26.26-5

3o-6

I. i. iS. 44-08

i. 15.48-30

82. 37. 17-0

61. 22-9

16.45-2

55.45. 19-50

56.37. io-5

II. i. 19.43-92

i. i5. 5o-56

82.36.59-5"

61. 22-9

16.45-2

55.44. 45-60

56. 36.32-9

14-8

I. i. 3i. 56-53

i. 1 6. 18-40

82. 33.25-2

61. 23-o

i6.45-3

58.56.27-15

5g. 34. 5i -9

II. 1.32.56-36

i. 16. 20-67

82.33. 7-7

61. 23-o

16. 45-3

58.55.53-ic

59. 34. 14-2

17-5

I. o. 24. 3 1 -04

2. 9.34-7I

76. 6. 20 -6

61.26-6

16.46-3

29.42. 22 "50

29. 26. i6-3

II. o.25.3o-88

2. 9.37-09

76. 6. 4-6

61.26-6

16.46-3

29. 41. 46-80

29. 25. 38 -4

3l'2

I. o.36. 7 -Si

2.10. 2-38

76. 3. 13-9

61. 26-5

16.46-3

32.3o. 3-i5

32. 2. 2'7

II. 0.37. 7-35

2. IO. 4-75

76. 2.57-8

61.26-5

16.46-3

32. 29. 27-60

32. I. 25-0

24-5

I. o. 54. 54-07

2. 10. 47- 16

75. 58. 12-2

61.26-5

1 6. 46 • 2

37. I. 15-90

36. i5. 14-8

II. 0.55.53-90

2. IO. 49-54

75.57.56-2

61.26-5

16. 46-2

37. 0.40-20

36. 14. 37-3

34-7

I. i. 5. 7-14

1. II. II '55

75.55.28-3

61. 26-4

1 6. 46 • 2

39.28. 51-45

38.33.27-o

II. i. 6. 6-98

2. I J. I3-93

75.55. 12-3

61. 26*4

16.46-2

39.28. i5'75

38. 32.49-0

23-5

I. 1.17.36-54

2. ii. 41 -36

'75.52. 8-1

61. 26-4

16.46-2

42. 29. 15-90

41. 22. 35-i

II. i. 18.36-37

2. II.43-75

75.5i. 52-2

61. 26-4

1 6. 46 • 2

42. 28. 40-05

41. 21. 57-2

' 28-4

I. i. 24. 40-30

2. ii. 58'24

75. 5o. i5'o

61.26-3

16.46-2

44. ii. i6-65

42. 58. 16-9

II. i. 25. 40-14

2. 12. o-6a

75.49.59-1

61.26-3

16.46-2

44. 10. 40-95

42.57.39-2

26-3

7.32.44-62

84.27. 8-1

—

—

33. 16. 57-45

35. 52. 14-5

—

? >

"

—

—

3i.i7.33-6o

34. 9. 9-7

—

I. 1.22. 3-5?

3. 10.44-78

69.58. 0-4

61. 9-2

16.41-5

29.49.29-55

28. 5.42-9

II. 1.23. 3-41

3. 10.47-29

69. 57.47-2

61. 9-2

16. 41-5

29. 48. 51-90

28. 5. 5-5

33-o

I. i. 3o.48-85

3. ii. 6-83

69.56. 5-o

61. 9-1

16.41-5

•31.55.39-45

3o. 4.39-2

II. 1.31.48-69

3. ii. 9-35

69. 55. 5i-8

61. 9-1

16. 41 -5

3i.55. i-65

3o. 4. 2-4

34-i

I. I.37.33-26

3. U.Z3-82

69.54. 36-2

61. 8-9

16.41 -4

33. 32.47-40

3i.36. 9-2

II. 1.38.33-09

3.II.26-33

69. 54. 23 • i

61. 8-9

16.41-4

33.32. 9-75

3i.35. 32-2

36-6

I. i. 5o. 22 '77

3. ii. 56-15

69.51.47-7

61. 8-7

16.41-4

36.37. 36-75

34. 3o. 2-0

II. i. 5i. 22-60

3. ii. 58-66

69. Si. 34-6

61. 8-7

16.41-4

36.36.59-10

34. 29. 25-o

22*2

I. i. Sg. 5-91

3. 12. i8-i5

69.49.53-3

61. 8-5

16.41-3

38. 43. i5-3o

36.18. 3-o

II. 2. 0. 5-75

3. i a. 20-66

69. 49. 40-2

61. 8-5

16.41-3

38.42.37-65

36. 27. 26-0

I9-5

I. 2.18.55-74

3.i3. 8-19

69.45.33-9

61. 8-2

1 6. 41*2

43. 29. i -o5

40. 55. 5i-8

II. 2.19.55-58

3. i3. 10-71

69. 45. 20-4

61. 8-2

16.41*2

43. 28.23-25

40. 55. 14-6

26-6

October 24. The aperture of the telescope was reduced for some of the observations.

148

TRANSIT OF VENUS, 1874. HONOLULU.

Day.

|

O

Object.

Altazimuth -
Clock Time
of Vertical
Transit over
Mean of
Horizontal
Wires.

k

i

H
P<

Heading of
Vertical
Circle
corrected for
Huns of
Micrometers.

Level Indication (ad-
ditive").

Barometer and Ex-
ternal Thermometer.

Kefraction.

True observed
Zenith
Distance.

1874.
October z5

T

Moon's U. L. . . .

h in s

6. 14. 2'o8

L

0 / '/

312.45.45-3

70-6

5l'2

42. 47. 25-8

26

T

AldebavaB

6. 32. 50-24

6. 42. 22 '86
7. 1 5. 39' 20

o. 49. 43 '80

It
K

B

U

223. 0.58-1

237.42.40-4
229.58. 5'7

225. 16. 4-9

71-1

71-2
71-2

66-6

3oln • 1 1
74° -2

73°-5

59-3

35-o
46-5

54-9

46. 59. ii '4

32. 17. 4-7
40. i. 5o'9

44-44- 4' 7

Moon's L. L, ...

? » ...

o. 58. 47 '04

i,

3 1 2. 42. 29- 8

75-4

5l'2

42. 44. i5- 1

, , ...

I. 21. 6-80

i.

307.46. 32-7

75-4

43-0

37.48. 9-8

, , • • •

I. 27. 56 '04

],

3o6. 1 5. 59-3

75-6

40-7

36. 17. 34-3

> ) • • •

i. 34.33-22

U

z35. 10. 2O-o

66-0

38-5

34.49. 33-8

SI

, , ...
Aldebanui

1.40. 9-26

i. 49. 59-82
i. 55.49-92
2. 3.38-16

2. 11. 26-5o

5.46. 38-14

n

K
R
L
L
L

236. 24.46-8

232. 3i. 1-6
233.52. 32-6
304. 16. 53-0
3o2. 27. 56 -9
29r. 55. 3i-7

65-5

66-0
66-0
73-i
74-0
69-8

3oin-i6
73°-6

36-8

42-5
40-4
37'8
35-3

22-3

33.35. 5-8

37.28. 56-2
36. 7.23-1
34. 1 8. 22-6
32. 29. 24-9
21. 56. 42-5

> ?

Moon's U. L. ...

» >

5.57.25-I6

I,

294. 18. i3-6

70-0

25-0

24. 19.27-3

>t • • •

. 6. 6. 59-08

L

296.24.49-3

70-8

27-5

26.26. 6-3

, , ...

6. 16. i3-38

R

241. 3i. i3-3

72-0

3o-o

28. 28. 26-0

, , ...

6.25. 9-86

H

239. 3z. 56-6

71-2

32-6

3o. 26. 46- 1

j » ...
Procyon

6.33.36-88

6.53.46-66
7. 4. ii-oo

U

R
1.

237.41. i5'4

251.48. 18-0
287. 2.48-8

70-6

70-0
66-2

3oin-i3
72°- 5

35-o
18-2

17-0

32. 1 8. 3o-3

18. ii. n-5

17. 3.5o-7

0 / //

October 26. The adopted Zenith point corresponding to the mean wire is 270. o. 21 • 3

TABLE IX. — LONGITUDE FROM THE MOON'S OBSERVED ZENITH DISTANCE (confirmed). 149

Greenwich Mean
Solar Time,

Tabular Geocentric Elements
(ll. A. and N. P. D. corrected).

Tabular Zenith
Distance of

Inferred
Longitude

assuming the West
Longitude to be
I. ioh. 3 1"1. os.

II. I0h. 32m. 0s.

Apparent
Bight
Aseeusiou
of Center.

Apparent
North Polar
Distance
of Center.

Equatorial
Horizontal
Parallax.

Semi-
diameter.

Hour-Angle.

Star or
of Limb of
Moon.

West of
Greenwich
ioh. 3i™. +

ll 111 S

ll III S

0 / //

/ //

/ //

O f ft 0 / //

N

I. 2.27.13-61

3. 1 3. 29-14

69.43.45-6

61. 8- o 16. 41 - 2

45.28.35-25 42.47.37-9

II. 2. 28. l3'45

3. i3. 3i-66

69.43. 32-6

6 1. 8-0 16.41-2

45. 27. 57-45 42. 47. 0-8

I9-0

I. 2. 45. 58 -73

3. 14. i6-5o

69. 39.41-6

61. 7-6

16. 41 • i

49.58.48-00 46.59.33-0

II. 2.46.58-57

3. 14. 19-02

69. 39.28-6

61. 7-6

16.41-1

49.58.10-20 46.58.55-9

34-9

4. 28. 44-81

73.44.29-4

—

—

33.44-53-25 32.17. 3-o

—

"

"

—

—

42. 4. o • oo

40. I. 52-2

I. 20.59.56-37

4. i. ii -40

66. 8.42-5

60.41-7

16. 34-0

47. 3o.35-25

44.43.46-6

II. 21. O. 56-20

4. i. 14-01

66. 8.32-5

60. 41-7 16. 34- o

^47. 3i. 14-40

44.44.2I-0

3i-6

I. 21. 8.58-14

4. i. 35-02

66. 7.11-8

60. 41 -4 1 6. 33-9

45. 20. 40-65

42.43. 57-5

II. 21. 9.57-98

4. i.37-63

66. 7. 1-7

60. 41 -4 1 6. 33-9

45. 21. 19-80

42. 44. 32- 1

3o-5

I. 21. 3l. I4'3l

4. 2.33-3i

66. 3. 29-2

60.40-8 i6.33-8

40. o. 17-70

37.47.51-3

II. 21. 32. 14- 14

4. 2.35-93

66. 3. i9-3

60.40-8 16.33-8

40. o. 57-00

37.48.26-3

3i-7

1. 21.38. 2-46

4. 2. 5i-i3

66. 2.21-5

60. 40-6 1 6. 33-7

38. 22. 26-10

36. 17. i5-6

II. 21. 39. 2'3o

4. 2.53-73

66. 2. 1 1 -6

60. 40* 6

16.33-7

38.23. 5-io

36. 17. So- 5

32-1

1. 21.44.38-58

4. 3. 8-41

66. 1.15-9

60.40-5 16.33-65

36. 47. 27-30

34.49. i6'8

II. 21. 45. 38-4I

4. 3. n-o3

66.. i. 6-0

60.40-5 16.33-65

36.48. 6-60

34.49.52-2

28-8

I. 21. 5o. 13-71

4. 3. 23-04

66. o. 2o-5

60. 40- 3 16. 33-6

35.27. 5-85

33. 34.48-9

II. 21. 5i. 13-55

4. 3.25-65

66. o. 10-6

60. 40 • 3 1 6. 3 3 • 6

35. 27.45-00 33. 35. 24-0

18-9

4.28.44-83

73.44.29-4

_ _

39. 19. 54-00

37.28. 59-0

—

, ,

, ,

— —

37. 52. 22-2O

36. 7.26-6

—

, ,

,,

— —

35.55. i8-3o

34. 18. 25-9

—

, ,

, ,

—

33. 58. 12-90

32. 29. 27-0

I. 1.56. 2-95

4. 14. 8-96

65. 21. i3-i

60. 33-2 16. 31-7

23. 28. 49 -5o

21. 57. o-3

II. i. 57. 2-78

4. 14. n-58

65. 21. 4-0

60. 33-2 16. 3i'7

23. 28. IO'2O

21. 56.24-8

3o-i

I. 2. 6.48-23

4. 14. 37 -3o

65. 19. 34-6

60. 32-9 16. 3i -6

26. 3. 3o-i5

24. 19. 44- 1

II. 2. 7.48-07

4. 14. 39-93

65. i9.25-5

60. 32-9

16. 3i-6

26. 2. 5o'7o

24.19. 8-8

28-6

I. 2. l6. 2O' 60

4. i5. 2-46

65. 1 8. 7-6

60. 32-6

16. 3i-5

28.20.41-85

l6. 26. 22* O

II. 2. 17. 20-44

4. 1 5. 5-09

65. 17. 58-4

60. 3z-6

i6.3i-5

28. 20. 2-40

26. z5. 46- 8

26-8

I. 2.25.33-42

4. 15.26-75

65. 16.43-7

60. 32-3 16. 3i'4

3o. 33. 12-45

28.28.39-3

II. 2. 2\ 33-25

4. i5. 29- 38

65. 16.34-7

60. 32-3 16. 3i'4

3o. 32. 33-00

28.28. 3-6

22-3

I. 2.34.28-47

4. 1 5. 50-27

65. i5. 22-8

60. 32- 1 1 6. 3 1 -4

32. 41. 17-45

3o. 26. 57-4

II. 2.35.28-3i

4. 1 5. 52-89

65. iS. i3-8

60. 32-i

1 6. 3 1-4

32. 40.48-15

3o. 26. 21-7

19-0

I. 2. 42. 54-I4

4. 16. 12- So

65. 14. 6-6

60. 3i-8

16. 3i-3

34.42. 39-75

32. 18.41-0

II. 2.43.53-97

4. 16. i5- 1 3

65. 13.57-6

60. 3 1 ' 8

16. 3i-3

34.42. o'3o

32. 18. 5-o

17-8

7. 32. 44-68

84.27. 8-3

—

—

9.22. 55-35

18. ii. 12-8

—

••

'•

—

—

6. 46. 49- 80

17. 4. i-3

~^~"

October 26. The aperture of the telescope was reduced for some of the observations.

u 2

150

TRANSIT OF VENUS, 1874. HONOLULU.

Day.

O

Object.

Altazimuth-
Clock Time
of Vertical
Transit over
Mean of
Horizontal
Wires.

ft

S
B

0,

1

Reading of
Vertical
Circle
corrected for
Runs of
Micrometers.

Level Indication (ad-
ditive).

Barometer and Ex-
ternal Thermometer.

Refraction.

True observed
Zenith
Distance.

1874.
October 27

T

Moon's L. L. . . .

h m s

i. i5. 52-72

U
R

o / //

216. 55. 9-4

2l8. 22. 48-0

64-8
65-3

73-7
69-9

O .' //

53. 5.18-8
5i.37.35-9

i. 22.42-96

,,

i.53.35-o6

L

314. 58. 23-o

75-8

3oin-2o

55-4

45. o. 14-9

,,

2. 0.35-46

L

3i3. 27. 59-4

76-0

74° -o

52-6

43. 29.48-7

Nl

Moon's U. L. . . .

7. I. 9-08

H

246. i. io'o

69-8

7*"7

24-7

23. 58. 24-2

,,

R

244. 14. 41 • 5

69-8

26-7

25.44. 54-7

5 j ...

Capella

7- 17.34-88

7- 29. 26-92
7.37.33-02

R

R
L

242. 3o. 58-o

23l. 50.45-3

309. 23. 14-1

69-7

66-2

72-6

28-8

43-5
45-5

27. 28. 40-4

38. 9. n'3
39. 24. 52-9

Moon's U. L. . . .

7.47. 18-88

L

303.49. 39-8

70-9

37'2

33. 5i. 8-6

,,

7.54.57-12

L

3o5. 28. 3-5

71-2

3oin.j7

39-5

35. 29. 34-9

"

8. 2.48-14

L

307. 9. 9-4

71-2

73°-6

42-0

37. 10.43-3

28

MI

Moon's L. L. ...

1.41.51-82

R

221. 6. 39-2

62-4

72° -6

63-5

48.53.41-7

,,

2.48.30-68

R

222. 3l. 23-1

62-4

6o-5

47.28. 54-8

,,

2. 54. i3-z8

R

223.44. i*'7

63-2

58-o

46. 1 6. 1-9

••

,,

3. 3.51-02

L

314. 11. i5'9

76-8

54-0

44. 1 3. 6-9

,,

3. 26. 14-30

L

309.25. o-3

77-0

3o'°-i5

45-6

39.26.43-1

Procyon

3.48. 5-44

3.58.5i-22
4. 8.58-36

L

L
R

304.45. 32-6

323. 38.58-9
218. 38. 39-9

77-2

74'7
65-6

72° -7

38-5

75-3
69-3

34.47. 8-5

53.41. 9-1
5i. 21.43-6

0 / .//

October 27. The adopted Zenith point corresponding to the mean wire is 270. o. 19- 3
October 28. „ „ „ 270.0.19-8

TABLE IX. — LONGITUDE FKOM THE MOON'S OBSERVED ZENITH DISTANCE (continued). 151

— —

Greenwich Mean
Solar Time,

Tabular Geocentric Elements
(R. A. and N. P. D. corrected).

Tabular Zenith
Distance of

Inferred
Longitude

assuming the West
Longitude to be
I. ioh. 3im. os.

II. J0h. 32™. 0".

Apparent
Right
Ascension
of Center.

Apparent
North Polar i
Distance
of Center.

Equatorial
Horizontal
Parallax.

*

Semi-
diameter.

Hour- Angle.

Star or
of Limb of
Moon.

West of
Greenwich
ioh. 3im. +

h • •

.

/ //

0 , „ 0 , „

I. 21. 22. 9-46

5. 5.54-47

62.58. 3i-6

59-54-5

16. 21 -i

57. 8. 1-95 53. 5.10-8

II. 21.23. 9'29

5. 5.57-15

61.58.26-2

59.54-5

I 6. 21- I

57. 8.42-15 53. 5.45-8

i3-7

I. 21.28.58-59

5. 6. 12-77

62.57.54-5

59.54-3

1 6. 11 -o

55. 3o. 2-55 51.37.27-3

II. 2I.29.58-4?

5. 6. i5'44

62. 57.49-1

59.54-3

16. 21-0

55.3o.42-6o 5i.38. 2-1

14-8

I. 1I.59.45-75

5. 7-35-34

61.55. 8-7

59.53-2

1 6. 20 • 7

48. 7. 37-95 ' 45. o. 2-3

II. 22. 0.45-59

5. 7-38-02

62.55. 3-4

59-53-2

16. 20-7

48. 8. i8-i5 45. o. 37-8

21-3

I. 22. 6.45-03

5. 7-54-09

62. 54. 3i-5

59. 52-9

1 6. 20 -6

46.27.12-75 43.29.35-1

II. 22. 7. 44- 87

5. 7.56-76

62. 54. 26-2

59.52-9

1 6. 20 -6

46. 27. 52-8o j

43. 3o. 10-6

12-9

I. 3. 6.3o-34

5.21. 18-59

62. 3o. 26-0

59.41-9

16. 17-6

25. 20. 18-00

i3. 58. 36-3

II. 3. 7. 3o-i8

5. 21. 21-17

62. 3o. 21 -7

59.41-9

16. 17-6

25. 19. 37-80

23.58. 2-0

11-2

I. 3. 14. 49-16

5. 21. 40-91

62. 29. 5o-2

59.41-6

16. 17-5

27. 19.45-90

i5.45. 6-7

II. 3. 15.49-00

5. 21.43-59

62. 29. 45-9

59.41-6

16. i7-5

27. 19. 5-70

25.44. 32-3

10-9

I. 3. 21. 53-5i

5.22. 2-58

62. 29. i5'7

59.41-3

16. 17-5

29. i5. 46-05

27.28.50-3

II. 3.23.53-34

5.22. 5-26

62. 29. 11-4

59.41-3

16. i7-5

29. i5. 5-85

27. 28. 15-4

I7-0

5. 7.17-19

44- 7-51-9

—

—

35.52.38-10

38. 9. 8-0

—

» )

» >

—

—

37. 54. io-o5

39.24. 41-6

—

I. 3.52.32-74

5. 23. 22-18

62. 27. 10-6

59.40-2

16. 17-2

36.21.53-55

33.5i. 18-6

II. 3.53.32-57

5.23.24-86

62.27. 6-4

59.40-2

1 6. 17-2

36.21. i3-35

33. So.43-3

I7-0

I. 4. o. 9-74

5.23.42-63

62.26. 38 -9

59.39-9

1 6. 17-1

38. n.20-55

35.29.42-1

II. 4. i. 9-57

5.23.45-3o

62. 26. 34-8

59.39-9

16. 17-1

38. 10.40-50

35.29. 6-8

12-2

I. 4. 7. 59-5i

5.24. 3-64

62.26. 6-6

59.39-7

16. 17-0

40. 3. 5fi5

37. io. 5o'8

II. 4. 8.59-34

5.24. 6-32

62.26. 2-5

59-39-7

16. 17-0

40. 3. 10-95

37. io. iS'l

12-6

I. 22.44. 3-66

6. 13.46-16

61.43.47- 5

58.56-2

16. 5-2

52.34. 54-i5

48.53.3o-7

II. 22.45. 3-49

6. 13.48-80

61.43.47-1

58.56-2

16. 5-2

52.35.33-75

48.54. 5-4 19-0

I. 22. 5o. 41 -45

6. 14. 3 • 74

61.43.44-6

58.56-c

16. 5-2

5o. 59. 34-65

47.28.45-4

II. 22.5l.4fl9

6. 14. 6-38 I 61.43.44-2

58.56-0

16. 5-2

5i. o. 14-23

47.29.20-1 16-2

I. 22. 56. i3; 1 5

6.14.18-82 61.43.42-2

58.55-7

16. 5-i

49.37.41-40

46. 15.52-6

II. 22. 57. 22-99

6.14.21-47 61.43.41-8

58.55-7

16. 5-i

49. 38. 21 -i5

46. 16. 27-8 15-9

I. 23. 5.39-33

6.14.44-27 61.43.38-4

58.55-4

16. 5-o

47.19.36-75

44. 12. 52-6

II. 23. 6.59-17

6.14.46-91 61.43.38-0

58.55-4

16. 5-o

47. 20. I6-35

44.13.27-5 14'6

I. 23.28. I9-03

6. 15.43-41

61.43. 3o-6

58. 54-4

16. 4-7

41.58.33-45

39. 26. 29-5

II. 23.29.18-86

6. 1 5. 46 -o5

6i.43. 3o-3

58.54-4

16. 4-7

41. 59. i3'o5

39.27. 4-2

23'5

I. 23. 5o. 6-64

6. 16. 41-10

61. 43. 24-6

58.53-6

16. 4-5

36.45. io- So

34.46.53-5

II. *3. 5i. 6-48

6. 1 6. 43-74

61.43. 24-3

58.53-6

16. 4-5

36. 45. 50-40

34.47.28-2

25-9

7- 32.44-74

84.17. 8-5

—

—

53. 4-38-iQ

53.41. 12-4

—

"

- '

—

—

5o. 32. 5o-55

5i. 21. 48-0

—

152

TRANSIT OF VENUS, 1874. HONOLULU.

Day.

•
0

Object.

Altazimuth-
Clock Time j
of Vertical
Transit over -a
Mean of
Horizontal
Wires. L g

Heading of
Vertical
Circle
corrected for
Huns of
Micrometers.

«
.2

rt
O

a'?

Barometer and Ex-
ternal Thermometer.

|
|

True observed
Zenith
Distance.

1874.
October 29

NI

Moon's L. L. . . .

h ni «

4. 10. i6-5o

u

226. 8. 21-7

61-8

72° -9

//

53-2

43. 51.49- 5

"

4. 20. 23 " 84

K

228. 18.55-8

6,-4

49-3

41. 41. u -9

,,

4. 32. 27-22

R

23o. 54. 35-o

6,5

45-0

39. 5.28-3

,,

4.47. 32-40

L

305.48.44-7

78-0

40-0

35. 5o. 22-9

,,

4.55. 52-98

I

304. o. 54-7

78-8

37-4

34. 2. 3i • i

November 4

T

Procyon

5. 4. 9 -36

5.24.31-40
5.54. 1-44

8. 16. 32-oo

t,

L
H

U

3o2. i3. 59-4

304. 25. 25-7
241.42. 4-5

206. 27. 37-1

79-0

75'2

66-0
66-0

3o'"-o5
72°-o

35'o

38-o
29-8

in • i

32. i5. 33-6

34. 26. 59-1
28. 17. 39-1

63. 33.28-4

Moon's L. L. ...

:,

8. 27. 50-90

R

208. 57. 25-i

64-8

3oLn-io

lOO'I

61. 3.3o-6

,,

9. i. 0-22

£

323.46.48-1

74'4

7i°-o

75-8

53.48. 57-9

5

NI

Moon's L. Ei. ...

8.42. 18-18

L

340. i o. 45-1

76-8

30""I2

i52-5

70. 14. 14-0

,,

8. 54. 19-26

R

202. 23. Si 'I

61-6

73°'7

i33-5

67. 37.41-2

'4

NI

Moon's L. L. . . .

o. i3. 38-40

L

344.38. 1-6

54'2

199-6

74.41. 55-o

,'.

o. 55. 12- 5o

u

187.38. 58-4

88-0

389-6

82.26.23-6

,,

i. 3.55-44

R

1 86. o. 4-9

87-8

3oin-i2

482-2

84. 6. 49 • 9

I. 12. 39-28

L

355.37.2I-3

5i-8

10° ••!

63i-i

85.48.23-8

i5

NI

Moon's L. L. ...

0.45. 35'6o

\.

338. 5. 5-4

52'6

66° -2

i38-3

68. 7.55-9

o / /'

October 29. The adopted Zenith point corresponding to the mean wire is 270. o. 19-8
November 4 to November 1 5. The adopted Zenith point corresponding to the mean wire is 270°. o'. 20" • 4

TABLE IX. — LONGITUDE PROM THE MOON'S OBSERVED ZENITH DISTANCE (continued). 153

Greenwich Mean
Solar Time,
assuming the West
Longitude to he
I. ioh. 3ir". o5.

II. I0h. 32'". 0".

Tabular Geocentric Elements
(It. A. and N. P. D. corrected).

Hour- Angle.

Tabular Zenith
Distance of
Star or
of Limb of
Moon.

Inferred
Longitude
West of
Greenwich
ioh. 3im. +

Apparent
Right
Ascension
of Center.

™ S±S

Distance p.,-,]].,,,
of Center.

Semi-
diameter.

li m s

h m K

o / //

o in

0 / II

1. o. 8. 22-90

7. 19. 36-ig

62. 31.45-9

57.55-1

15.48-5

46.55. o-i5

43. 5i.38-7

]]. o. 9.22-74

7. 19. 38-68

62. 3i. 5o-o

57. 55-i

15.48-5

46.55.37-50

43. 52. n'9

i9-5

I. o. 18. 28-61

7. 20. i ' 60

62. 32. 27-5

57.54-7

15.48-4

44.29. 30-75

41.41. 1-7

11. o. 19. 28-44

7. 20. 4-11

62. 32. 3i-y

57.54-7

15.48-4

44. 3o. 8-40

41.41. 35-o

18-4

I. o. 3o. 3o'O4

7.20. 3i-85

62. 33. 17-5

57.54-2

15.48-3

4i.36.i3-35

39. 5.i6-6

II. 0.31.29-88

7. 20. 34-36

62. 33. 21-7

57.54-2 .

15.48-3

41. 36. 5i-oo

39. 5.49-8

21-1

1. o. 45. 32'79

7.21. 9-69

62. 34. 20 -6

57.53-6

15.48-1

37. 59. 22-5o

35. 5o. 12-8

11. 0.46.32-63

7. 21. I2-2O

62. 34. 24-8

57.53-6

15.48-1

38. o. o-iS

35.5o.46-i

18-2

I. 0.53.52-01

7. 21. 3o-6o

62. 34. 55-8

57.53-3

15.48-0

35.59.27-45

34. 2. 2O'O

11. o.54.5i-85

7. 21. 33- ii

62. 35. o-o

57.53-3

15.48-0

36. o. 5-io

34. 2.53-1

2O ' I

I. 1. 2. 7-09

7.21.51-33

62. 35. 3o-8

57-52-9

15.47-9

34. 0.31-95

32. l5. 22-2

II. i. 3. 6-93

7.21.53-84

62. 35.35-1

57.52-9

15.47-9

34. i. 9-60

32. i5. 55-3

20-7

7.32.44-78

84.27. 8-6

—

—

3i.38.22-35

34.27. 2-3

—

) »

5 >

— •

—

24. 1 5. 5o-25

28. 17. 37-8

I. 3.50.47-41

12. 19. 50'02

89.58. i5-8

54- 8'7

14.46-8

60. 18. 21-60

63. 33.21-2

II. 3.51.47-25

12. 19. 5l-76

89.58.29-9

54. 8-7

14.46-8

60. 1 8. 47-70

63. 33. 5o-8

14-6

1. 4. 2. 4'5o

12. 2O. 9-69

90. o. 54-4

54. 8-6

14.46-7

57. 33.32-55

61. 3.20-1

II. 4- 3. 4-34

12. 2O. 11*42

90. i. 8-5

54. 8-6

14.46-7

57.33.58-So

61. 3.49-7

21-3

I. 4.35. 8-47

12. 21. 7'3o

90. 8. 39-2

54. 8-3

14. 46-6

49. 3o. 35-55

53.48.47-9

II. 4-36. 8-3i

12. 21. 9'O3

90. 8.53-3

54. 8-3

14. 46-6

49. 3i. i -5o

53.49. 17'4

20-3

I. 4. 10. 24-42

1 3. 2. 16-64

95. 37. 34-8

53.59-6

14.44-2

65. 0.49-20

70.14. 4-4

II. 4. n. 24-25

i3. 2.18-39

95. 37.48-5

53.59-6

14.44-2

65. i.i5'45

70. 14. 33-9

19-5

1. 4. 22. 23-52

i3. 2.37-66

95. 40. 19-8

53.59-6

14.44-2

62. 5.48-30

67. 37. 30-9

11. 4.23.23-36

i3. 2. 39-41

95.40. 33-5

53.59-6

14.44-2

62. 6.14-55

67.38. o-3

23-2

I. 19. 7-54-39

20. I 8. 23-26

1 1 5. 0.47-0

56. 27-6

1 5. 24-6

58.49.59-55

74.42. 7-5

II. 19. 8.54-22

20. 18.25-56

n5. o. 39-6

56.57-6

i5. 24-6

58.49.25-05

74.41.37-4

24-9

I. 19.49.21-72

20. 19. 58-46

114. 55. 33-5

56.28-8

i5.25-o

68.49.43-65

82.26. 35-5

11. 19. 5o. 21-56

2O. 20. 0-75

114. 55. 25-9

56.28-8

iS.25-0

68.49. 9'3°

82.26. 4-5

23-0

J. 19. 58. 3-25

2O. 20. 18-34

114.54.27-2

56. 29-0

i5.25-o

70. 55. 29-70

84. 7. 0-7

II. 19.59. 3-o8

20. 20. 20-69

114. 54. 19-6

56. 29-0

iS.25-0

70. 54. 54-45

84. 6.28-9

20-4

I. 20. 6.45-67

20. 20. 38-39

114. 53. 20-6

56.29-3

i5.25-i

73. 1.26-70

85.48.28-8

II. 20. 7.45-50

20. 20. 40-68

114. 53. 12-9

56. 29-3

i5.25-i

73. 0.52-35

85.47.57-5

9-6

I. 19-35.51-38

21. 13.44-99

in. 16. 35-4

57. ii-6

i5. 36-6

52.59. 5-55

68. 8. 7-6

11. I9.36.5I-22

21. 13.47-21

in. 16. 24-7

57. 11-6

iS.36-6

52.58.32-25

68. 7.36-3

22-4

November 4. Cloudy. Observations unsatisfactory.

154

TRANSIT OF VENDS, 1874. HONOLULU.

Day.

Observer.

Object.

'*"
Altazimuth-
Clock Time i
of Vertical
Transit over £
Mean of xs
Horizontal
Wires.

Reading of
Vertical
Circle
corrected for
Runs of
Micrometers.

Level Indication (ad-
ditive). •

Barometer and Ex-
ternal Thermometer.

d

0

•a

B

True observed
Zenith
Distance.

1874.
November i5

Nr

Moon's L. L. ...

h in s

o. 55. 41' 20

L

O t ff

339.55.28-5

//
52-6

I 52' 2

69. 58. 32-9

,,

i. 2. 54-80

L

341. i5. 21-8

52-6

i63-7

71.18.37-7

,..

i. 1 6. 88-70

R

196. 8.28-4

89-8

191-0

73.53.33-2

» » • * •

i. 26. 20-46

K

'94- «7-47'4

89-6

2l6'2

75.44. 39-6

, , ...

1.37. 16-54

B

192. ii. 25-o

89-1

253-4

77- 5i. 39-7

S Capricorni ....

i. 46. 49-98

E

198. 36.43-2

88-8

3o'n-o8

i65-i

71.24.53-5

j , ....

1.56. 45-54

L

343. 25. 20-9

Sl'2

64° '2

186-6

73.28.58-3

16

NI

Moon's L. L. ...

1.35. i5-i6

L

334. 17. 12-9

69-9

66° -7

nS'4

64. 19. 57-8

, , ...

i. 44. 10-64

L

335.59. 5'2

70-4

1 24 '6

66. 1.59-8

, , ...

i. 55. 4-70

R

201. 52. 59-5

71-6

137-9

68. 8.27-2

, , ...

2. 3.21-58

R

200. 1 5. 48-5

71-0

149-9

69.45. 5o-8

> > • • •

2. 1 3. i5-66

L

341.39.57-5

69- 1

167-0

71.43. 33-2

9 i • ' •

2. 23. 35-40

L

343.43.45-1

70-3

189-1

73.47.44-1

, , ...

2. 32. 33-48

K

194.26. 3-8

71-8

2l3'2

75.36. 38-o

•22

SI

, , ...

Ifonjalhaut

2.41. 7-26
2. 54. 20-40

3. i3. 6-56

4- 9-44'H
4.35. 7-58

R

R
L

L
R

192.41.43-4

192. 2.44-8
35i.i9.33-7

3oo. i. 19-8
234. 7.14-9

70-4

67-6
7'"4

84-8
56-o

3oin-o3
65° -i

242-6

255'4
35o-5

32-5
40-6

77.21.29-2

78. 0.43-4
81. 26. iS-2

3o. 2.54-7
35.52.52-i

ct Arietis . . .

Moon's L. L. ...

4.48. i3-3o

K

252. 54.46-9

57-4

i7-3

17. 4.55-4

, , ...

5. o. 40- 34

R

25o. 6.35-1

58-3

65°-7

20-3

19.53. 9-2

O f ff

November iS and 16. The adopted Zenith point corresponding to the mean wire is 270. o. 20-4
November 22. „ „ „ 270.0.22-4

TABLE IX. — LONGITUDE FROM THE MOON'S OBSERVED ZENITH DISTANCE (continued). 155

Greenwich Mean
Solar Time,
assuming the West
Longitude to be
I. ioh. 3im.o1'.
II. ioh. 32™. o".

Tabular Geocentric Elements
(R. A. and N. P. D. corrected).

Hour-Angle.

Tabular Zenith
Distance of
Star or
of Limb of
Moon.

Inferred
Longitude
West of
Greenwich
ioh. 3im. +

Apparent
Right
Ascension
of Center.

Apparent
North Polar
Distance
of Center.

Equatorial
Horizontal
Parallax.

Semi-
diameter.

ti m a

o m a

/ //

.

•

I. I9.4.5.56-33

.21.14. 7-44

Hi. 14. 47*2

57. 11-9

i5.36-7

55.25. 7-95

69.58.44-8

II. 19.46. 56- 17

21. 14. 9'66

in. 14. 36'4

57. 11-9

i5. 36-7

55.24.34-65

69. 58. i3-i

22-5

I. 19.53. 7-77

21. 14. 23-45

in. i3. 29-8

57. 12- I

i5. 36-7

57. 9.17-10

71. 1 8. 48-0

II. 19. 54. 7-61

21. 14. 25-67

in. i3. 19- 1

57. I2-I

i5. 36-7

57. 8.43-80

71. 18. 16-2

I9-4

I. 20. 6.49-44

21. 14. 53-93

III. II. 2-2

57. 12-6

i5. 36-9

60. 27. 38-70

73.53.43-5

II. 20. 7.49*28

21. 14. 56-i5

in. 10. 5i-5

57. 12-6

i5. 36-9

60. 27. 5-40

73.53. ii -5

I9-3

I. 20. 1 6. 29-62

21. 15. l5'45

in. 9. 17-8

57. 12-9

i5.36-9

62.47.42-45

75.44.54-0

II. 20. 17. 29-46

21. i5. 17-66

in. 9. 7-0

57. I2'9

i5.36-9

62.47. 9-30

75.44.21-9

26-9

I. 20. 17. 23 '94

21. i5. 39-70

in. 7.19-7

57- J3-2

15.37-0

65. 25. 40-20

77- Si.53-4

II. 20.28.23-78

21. i5. 41 -92

in. 7. 8-9

57. 13-2

i5.37-o

65. 25. 6-90

77. 5i. 21- 1

25-4

21.40. 7-47

106. 41. 46- 1

—

—

61.42. 5-55

71.24.54-9

—

"

"

—

—

64. 10. 59-25

73.29. i-3

—

I. 2O. 21. 27-55

22. 8. O-O4

106. 16. 2-9

58. 0-6

i5. 5o-o

Si. So. 22-95

64. 20. 7-0

II. 20.22.27-38

22. 8. 2-21

106. 15.49-4

58. 0-6

i5. 5o-o

51.49. 50-40

64. 19. 33-7

16-6

I. 20. 3o. 21 -57

22. 8. I9-25

106. 14. 3-o

58. 0-9

i5.5o-i

53.59.27-15

66. 2. 9-0

II. 20. 3i. 21-41

22. 8. 21*40

106. 1 3. 49-6

58. 0-9

i5.5o-i

53.58.54-90

66. 1.35-9

16-7

I. 20.41.13-86

22. 8.42-70

106. ii. 36-6

58. 1-2

i5. 5o-2

56.3?. 6-45

68. 8.39-9

II. 20.42. 13-70

22. 8.44-86

106. ii. z3-i

58. 1-2

i5. 5o-2

56. 36. 34-05

68. 8. 6-2

22-6

I. 20. 49. 29-39

22. 9. 0-52

106. 9 45-i

58. i-5

i5. 5o-2

58.36. 52 -5o

69.46. 2-1

II. 20. So. 29-23

22. 9. 2-68

106. 9.31-7

58. i-5

i5. 5o-2

58. 36.20-10

69.45.28-5

20-2

I. 20.59.21-85

22. 9. 2I-82

106. 7. 3i-8

58. 1-9

i5. 5o-3

61. o. 4-20

7I.43.45-7

II. 21. O. 21-69

22. 9. 23-96

106. 7.18-3

58. 1-9

i5. 5o-3

60. 59. 32- 10

71. 43. 12-3

22-5

I. 21. 9. 39-91

22. 9.44*03

106. 5. 12-5

58. 2-2

i5. 5o-4

63.29. 27-30

73.47-58-1

II. ai.IO.39-75

22. 9.46-18

106. 4. 59-0

58. 2-2

i5. 50-4

63.28.55-o5

73.47.24-4

24-9

I. 2i.i8.36-53

22.10. 3'3l

106. 3. ii -5

58. 2-5

i5. 5o-5

65. 39. 9-45

75. 36.5i-7

II. 2i.i9.36-36

22. IO. 5-46

106. 2. 58-o

58. 2-5

i5. 5o-5

65.38.37-20

75. 36. 18-1

24-5

I. 21.27. S'91

22. 10. 21-yJ

106. i. i5'8

58. 2-8

i5. 5o-6

67.43. o-oo

77.21.40-5

II. 20.28. 8-75

22. 10. 23-87

1 06. I. 2' 2

58. 2-8

i5. 5o-6

67.42.27-90

77.21. 6-9

2O- 2

22. 5O. 44'O9

120. 17. l6'4

—

—

60.55.41-85

78. 0.39-6

—

» >

, »

—

—

65. 37. 14-40

81. 26. 14-5

—

2. 0. 7-89

67. 7.39-8

—

—

32.26.5o-85

3o. 2.52-5

—

, ,

> »

—

—

38.47.42-75

35.52.49-3

—

I. 23.10.23-35

3.37.23-02

67.49.29-4

61. 3-5

1 6. 39-9

17.45.21-75

17. 5. 1-7

II. 23.11.23-18

3.37.25-60

67.49.17-9

61. 3-5

16. 39-9

17.44.43-05

17. 4.27-1

IO'9

I. 23.22.48-39

3.37.55-I8

67.47. 5-5

61. 3-4

16. 39-9

20.44. 5-io

19. 53. 18-7

II. 23.23.48-23

3.37.57-77

67.46. 54-0

61. 3-4

16. 39-9

20. 43. 26-25

19. 52. 42*8

,5-s

November i5, 16, and 22. The aperture was reduced.

156

TRANSIT OF VENUS, 1874. HONOLULU.

Day.

Observer.

Object.

Altazimuth-
Clock Time
of Vertical
Transit over
Mean of
Horizontal
Wires.

Lamp Right or Left. 1

' 1

Reading of
Vertical .2
Circle g

corrected for '*5 •
Runs of M j;
Micrometers. 73 -s

g^
4

Barometer and Ex-
ternal Thermometer.

Refraction.

True observed
Zenith
Distance.

1874.
November 22

KI

Moon's L. L. ...

h in » .

5. 8.38-44

•

L

248. ig.58-5
293. 44. 56-9

58-6
82-0

ff
22-4

24-8

o r ft
21.40.47-7

23.46. 21 -3

, , ...

5. 17. 57-22

> > • • •

5.27.39-84

I.

295. 55.41-8

82-8

3oin-i4

27-4

25.57. 9'6

) >

5.38. 13-34

L

298. 17.43-0

83-2

64° -2

3o-3

28. 19. 14'! .

23

M

Moon's U. L. . . .

4. 3.47-30

•

260. 18. 10-7

66-6

63° -2

9-6

9.41. 14-7

, , ...

4. 14. 5-58

11

262. u. 27-8

65'4

7'7

7.47. 56-9

» » ...

4.24.24-42

L

276. it. 2-5

78-4

6-2

6. 12. 4-7

Moon's L. L. ...

5.54. 4-08

L

286.46.45-6

77'4

63° -3

17-0

16. 47. 57-6

> t . « •

6. 2.28-50

L

288. 34.28-4

77-5

19-0

18. 35.42-5

> » ...

6. n.36-34

L

290. 32. ii -8

78-3

21-2

20. 33.28-9

j > ...

6. 19. 24-64

n

247.45. 4-3

67-0

23-1

22. 14. 34-2

26

HI

j > ...
Aldebaran

6. 27. 37-00

6.3?. 1-68
6.46. 29-72

4.44.25-52

11

K

L

L

245.58.36-i

239.13. 37-8
3o2. 56. 49-0

314. 6.58-7

66-2

68-0
72-8

77'3

63° -3

3oi"-i5
63° -o

64° -2

25-1

33-6
36-6

54-5

24. i. 5-2

3o. 46. 10-2
32.58. 16-0

44- 8. 49- 1

Moon's L. L. ...

,,

4. 52. 18-80

L

3i2. 24. i3-6

77-8

5i-3

42. 26. i-3

> > ...

5. i. 6-54

L

3io. 29. 27-8

78-6

48-0

40. 3i. i3-o

i > ...

5. 9. 5o-o6

B

23i. 22.46-2

66-3

44-8

38.37. i3-7

n ...

5. 17. 16-96

K

233. o. 9-0

65-8

3oin-oi

42-2

36. 59.48-8

O / '/

November 22 aud 23. The adopted Zenith point corresponding to the mean wire is 270. o. 22-4
November 26. „ „ „ 270. 0.21 '4

TABLE IX. — LONGITUDE FROM THE MOON'S OBSERVED ZENITH DISTANCE (continued). 157

Greenwich Mean
Solar Time,
assuming the West
Longitude to be

I. ioh. 3i"'. os.
II. ioh. 32'". o».

Tabular Geocentric Elements
(K. A. and N. P. D. corrected).

Hour-Angle.

Tabular Zenith
Distance of
Star or
of Limb of
Moon.

Inferred
Longitude
West of
Greenwich
iob. 3im. +

Apparent
Kight
Ascension
of Center.

Apparent E torial
J,ort, Polar H2rilontol
Distance
of Center. larallax"

Semi-
diameter.

ll III S

h n> s

0 / //

/ //

/ //

0 / //

0 / //

K

I. 23. 3o.45-i6

3.38. 15-78

67.45. 33-6

61. 3-3

16. 39-9

22. 38.27-75

21. 40. 54-0

II. 23.3i.45-oo

3.38. i8-35

67.45. 22-0

61. 3-3

1 6. 39-9

22. 37. 49-20

21. 40. i8-5

ID"?

I. 23.40. 2-42

3. 38.39-85

67.43.46-4

61. 3-2

16. 39-9

24. 52. 8-40

23.46. 32-2

II. 23.41. 2-26

3.38.42-45

67.43. 34-8

61. 3-2

16. 39-9

24. 5 i. 29-40

23.45. 56-o

18-1

I. 23.49.43-46

3.39. 4-97

67.41. 54-S

61. 3-1

16. 39-8

27. ii. 3i-o5

25. 57.23-7

II. 23. 50.43-29

3.39. 7-55

67.41.43-3

61. 3-i

16. 39-8

27. 10. 52-35

25. 56.46-9

22-9

I. o. o. 15-24

3. 39. 32-20

67.39.53-4

61. 3-o

16. 39-8

29.43. 5-25

28. 19. 3i-o

II. o. i. 15-07

3. 39.34-79

67. 39.4I-9

61. 3-o

16. 39-8

29. 42. 26-40

18. 18. 54-3

27-6

I. 22.22. 9-77

4. 38.58-20

64. 6. 16*6

60. 41 • 3

16.33-9

8. 44. 40-20

9. 40. 53-3

II. 22.23. 9'6l

4. 39. 0-89

64. 6. 9-1

60. 41 -3

16.33-9

8.45.20-55

9.41. 28-5

36-5

I. 22.32.26-36

4. 39. 26-06

64. 4.59-8

60. 41-0

16. 33-8

6. 17. 3-90

7.47. 36-o

II. 22.33.26-I9

4. 39. 28-76

64. 4. 52-4

60. 41 *o

16.33-8

6- "7-44'4°

7.48. ii -7

35-i

I. 22. 42. 43'52

4. 39.53-95

64. 3.43-2

60. 40 • 8

16.33-8

3. 49. ig-So

6. n.53-9

II. 22.43.43-36

4. 39.56-65

64. 3.35-8

60. 40 • 8

16.33-8

3. 5o. o-oo

6. 12. 21-5

23-5

I. 0.12. 8-52

4.43.56-57

63. 52.52-0

60. 38-8

16. 33-2

17. 34. 56-70

16.48. i5-5

II. 0.1 3. 8-36

4.43. 59-29

63. 52. 44-9

60. 38-8

16. 33-2

17. 34. 15-90

16.47.40-9

3i-o

I. o. 20. 3i'S7

4.44. 19-36

63.5i. 52-3

60. 38-6

16. 33-2

19. 35. 2i-i5

18. 36. 1-6

II. o. 21. 3i -41

4. 44. 22-06

63. 51.45-2

60. 38-6

16.33-2

19. 34.40-65

18.35.27-2

33-3

I. 0.29.37-93

4.44.44-11

63. 50.47-8

60. 38-4

16. 33-i

21.46. 7 -65

20. 33.46-6

II. 0.30.37-77

4. 44. 46 • 8 1

63. 5o. 40-6

60. 38-4

16. 33-i

21.45. 27-15

20. 33. ii -6

3o-3

I. o. 37. 14-95

4.45. 5-26

63.49. 52-8

6o.38-3

I6.33-I

23. 37. 54-90

22. 14. 49 "o

II. 0.38.24-78

4.45. 7-97

63.49.45-8

60. 38-3

i6.33-i

23. 37. 14-25

22. 14. 14-0

25-4

I. 0.45.35-98

4.45.27-52

63.48. 55-2

60. 38-i

16. 33-o

25. 35.26-55

24. 1.20-7

II. 0.46.35-81

4.45. 3o-23

63.48.48-3

60. 38-i

16. 33-o

25. 34.45-90

24. 0.45-2

26-2

4.28.45-38

73.44.29-4

—

—

32. 7. 8-85

3o. 46. 9 • 6

—

i »

» »

—

—

34.29. 9-60

32. 58. 14-7

—

I. 22.5o.58-24

7. 53. 17-02

63.49. 9'8

58. 14-2

i5. 53-7

47. 8.39-30

44- 8. 34-4

•

II. 22. 5i. 58-o8

7.53. 19-51

63.49. l6'3

58. 14-2

i5. 53-7

47. 9. i6-65

44- 9- 8-3

26-0

I. 22.58.5o-23

7.53.36-67

63. 5o. 0-7

58. 13-9

i5. 53-6

45. i5. 14-70

42. 25. 46-2

II. 22. 59. 50-07

7.53.39-16

63. So. 7-1

58. i3-g

15.53-6

45. i5. 52-o5

42. 26. 20 -o

26-8

I. 23. 7.36-54

7-53.58-56

63. So. Sj-6

58. i3-5

15.53-5

43. 8.46-95

40. 3o. 58- 7

II. 23. 8.36-37

7. 54. i • 04

63. Si. 4-0

58. i3-5

iS.53-5

43. 9.24-15

40. 3i. 32-3

25-5

I. 23.16.18-62

7. 54. 20-26

63. Si. 54-2

58. i3-2

i5. 53-4

41. 3. 19-65

38.36.57-9

II. 23.17.18-46

7. 54.22-75

63.52. 0-7

58. i3-2

i5. 53-4

41. 3. 57-00

38.37. 3i-7

28-0

I. 23.23.44-32

7.54.38-77

63. 52.41-7

58. 12-9

iS.53-3

39. 16. i3-65

36. 59. 32-5

II. 23.24.44-15

7. 54. 41-26

63. 52.49-2

58. 12-9

i5. 53-3

39. 16. 5i-oo

37. o. 6-2

29-0

November 23. Moon's limb indistinct. Aperture reduced.

x 2

158

TRANSIT OF VENUS, 1874. HONOLULU.

Day.

b
S

o

Object.

Altazimuth-
Clock Time
of Vertical
Transit over
Mean of
Horizontal
Wires.

Lamp Right or Left.

Reading of
Vertical
Circle
corrected for
Runs of
Micrometers.

Level Indication (ad-
ditive).

Barometer aud Ex-
ternal Thermometer.

Refraction.

True observed
Zenith
Distance.

1874.
November 26

NI

Moon's L. L. ...

5.23.57-86

K

0 / //

234.27. 37-4

65-7

65° -i

tr
40* o

0 t >t

35.32. i8-3

27

NI

Moon's L. L. ...

4.54. 2-42

L

325.27. 38-8

75-3

62° -o

81-8

55.29.54-5

» > ...

5. 1.51-28

L

323.44.46-5

75-i

76-8

53.46.57-0

j » • • •

5. 8.39-58

L

322. 14.58-5

75-2

72-8

52.17. 5-i

> » • • •

5. 16. n-38

L

320.35.25-7

75-o

68-6

So. 37.27-9

, , ...

5. 24.43-96

R

221. l6. 2- I

70-0

64-2

48. 44. 1 3 • 5

, , ...

5. 3i. 6-56

K

222. 40. 42-5

69-8

61-1

47. 19. 3o-2

, , ...

5.3.9-30-66

K

224. 32. 23-5

69-8

57'3

45.27.45-4

» > • • •

5.46. 51-48

a

226. 10. i5-3

69-7

54- 1

43. 49. 5o-5

» » ...

5.54-32-68

it

227. 52. 48-7

69-8

5i-o

42. 7. i3'9

, , ...

6. 2. 9-16

K

229. 34.28-8

69-4

48-2

40. 25. 3i-4

i » • • •

6. 9.45-78

L

308.41.57-3

72-6

45-2

38.43.33'7

, , ...

6. 17. 32-86

L

306.57. 38-3

73-6

60° -8

42-5

36.59. i3-o

28

NI

y Leonis

6. 35.28-io
6.44. 28-70

4. 29. 9-60

R

L

R

219. 3o. 24-9

318.23.41-7

196. 6. 3o-o

69-9

74-2

67-4

3o""o6
6i°-3

69° -9

68-4
63-6

190-8

5o. 29. 55-o
48.25.38-i

73.55.54-8

Moon's L. L. ...

, , ...

4. 39. 5 1 • 80

R

198. 26. 36-6

67-5

165-9

71. 35.23-2

» » ...

4. 48. 54- 38

R

2OO. 25. 25' I

67-3

149-0

69. 36. 18-0

, , ...

4-58.13-38

L

337. 3o. 1-4

71-4

134-4

67.33. 5-8

O / //

November 27 and 28. The adopted Zenith point corresponding to the mean wire is 270. o. 21 -4

TABLE IX. — LONGITUDE FROM THE MOON'S OBSERVED ZENITH DISTANCE (continued). 159

Greenwich Mean
Solar Time,
assuming the West
Longitude to be
I. ioh. 3i'".os.
II. ioh. 32m. os.

Tabular Geocentric Elements
(K. A. and N. P. D. corrected).

V

Hour-Angle.

Tabular Zenith
Distance of
Star or
of Limb of
Moon.

Inferred
Longitude
West of
Greenwich
ioh. 31™. +

Apparent
Right
Ascension
of Center.

Apparent
North Polar
Distance
of Center.

Equatorial
Horizontal
Parallax.

Semi-
diameter.

h in s

o / //

/ //

/ //

O 1 it

o

i

I. 23. 3o. 24-12

7.54. 55-38

63. 53.26-3

58. 12-6

15.53-2

37.40. 9-30

35.32. 5-4

II. 23. 3i. 23-96

7.54.57-86

63.53.32-8

58. 12-6

i5. 53-2

37. 40. 46-50

35.32.38-7

23-2

I. 22. 56. 39-00

8.5o.57-57

67. 4. 42' 6

57. 16-8

i5.38-i

Sg. 9. i3-65

55.29.37-5

II. 22.57.38-84

8.50.59-86

67. 4. 52'2

57. 16-8

I5.38-I

59. 9.48-00

55. 3o. io-3

3i-i

I. 23. 4.26-59

8. Si. 15-41

67. 5.57-5

57. i6-5

i5. 38-o

57. 16. 28-20

53.46.39-2

II. 23. 5.26-43

8. Si. 17-69

67. 6. 7-1

57. i6-5

15.38-0

57. 17. 2-40

53.47. 11-9

32-7

I. 23. 11.13-78

8. Si. 30-93

67. 7. 2-9

57. 16-2

i5.37-9

55. 38. i6-5o

52. 16.48-3

II. 23.12.13-62

8.5i. 33-21

67. 7.12-5

57. 16-2

i5.37-9

55. 38. So- 70

52. 17. 20-9

3o'9

I. 23.18.44-35

8. 51.48-09

67. 8.15-2

57. i5-9

iS.37-8

53.49. 36-90

So. 37. io-5

II. 23. 19.44-19

8. Si.So-Sy

67. 8. 24-9

57-15-9

iS.37-8

53. So. ii -io

So. 37.43-1

32-0

I. 23.27.15-54

8.52. 7-57

67. 9.37-5

57. i5-6

i5. 37-8

Si. 46. 20-25

48.43.55-4

II. 23.28.15-37

8. 52. 9 • 84

67. 9.47-1

57.15-6

i5.37-8

$1.46. 54'3o

48.44.27-9

33-4

I. 23.33.37-09

8. 52. 22-09

67. 10. 39-0

57. i5-3

i5.37-7

So. 14. ig-oS

47.19. 13-7

II. 23.34.36-93

8. 52.24-36

67. 10.48-6

57.15-3

'5.37-7

5o. 14. 53-10

47. 19.46-3

3o'4

I. 23.41.59-83

8. 52.41-22

67. 12. 0-1

57. i5-o

iS.37-6

48. i3. 4-35

45.27.27-1

II. 23.42.59-67

8.52.43-49

67. 12. 9'8

57. i5-o

15.37-6

48. i3. 38-4o

45. 27. 59-4

34-0

I. 23.49.19-44

8.52.57-93

67. i3. ii- 1

57. 14-7

15.37-5

46.27. 2-70

43.49.31-7

II. 23.50.19-28

8.53. 0-21

67. i3. 20-8

57. 14-7

iS.37-5

46. 27. 36-90

43. So. 4-2

34'7

I. 23.56.59-38

8.53. 15-42

67. 14. 25-6

57. 14-4

i5.37-4

44. 36. 7-05

42. 6.55-2

II. 23.57.59-22

8. 53. 17-69

67. 14. 35-2

57. 14-4

i5.37-4

44. 36. 41-10

42. 7- *7 '4

34-8

I. o. 4. 34-62

8.53.32-82

67. i5. 38-7

57. 14-1

i5. 37-4

42. 46. 20-70

40. 25. i3-5

II. o. 5. 34-46

8.53.35-10

67. 15.48-4

57. 14-1

i5.37-4

42. 46. 54-90

40. 25.45-8

33-2

I. O. 12. lO'OO

8.53. 5o-iz

67. 16.52-6

57. i3-8

iS.37-3

40. 56. 30-90

38.43.i9-4

II. o.i 3. 9-84

8.53.52-39

67. 17. 2-3

57-13-8

i5. 37-3

40.57. 4-9$

38.43. Si -7

26-6

I. 0.19.55-81

8.54. 7-80

67.18. 8-3

57. i3-5

15.37-2

39. 4. 9-90

36. S8. 56-4

II. o. 20. 55-64

8. 54. 10-07

67. 18. 18-0

57.13-5

i5. 37-2

39. 4.43-95

36.59.28-5

3i-o

10. i3. 4-17

69.31.33-4

—

—

54. 19. 26-70

So. 29. 55-3

—

» »

> )

—

—

52. 4. 17-55

48. 25. 38-2

—

I. 22.27.55-59

9. 42. 28-62

71. 17. 19-3

56. 24-2

iS.23'7

78. 14. 53-10

73.55.36-o

II. 22.28.55-43

9. 42. 30-71

71. 17. 3i-o

56. 24-2

15.23-7

78. 1 5. 24-45

73.56. 7-4

35-9

I. 22. 38. 36-oS

9.42. So -97

71. 19. 24-6

56.23-8

i5. 23-6

75.39.55-20

71.35. 6-1

II. 22.39.35-88

9.42. 53-o6

71. 19. 36-3

56.23-8

iS.23'6

75.40.26-55

7i.35.37-9

32-3

I. 22.47.37-14

9.43. '9-86

71. 21. io- 5

56.23-5

iS.23-5

73.28. 59-85

69.35.58-4

II. 22.48.36-98

9. 43. 11-95

71. 21. 22-3

56.23-5

iS.23-5

73. 29. 3i-2o

69. 36. 3o-o

37-2

I. 22.56.54-63

9.43. 29-31

71. 22. 59-8

56.23-2

15.23-4

71.14- 6-45

67. 32. 5o'5

II. 22.57.54-47

9.43.31-39

71. *3. ii-S

56.23-2

iS.23-4

71. 14. 37-65

67. 33. 22-0

29-1

160

TRANSIT OF VENUS, 1874. HONOLULU.

Day.

i

o

Object.

Altazimuth^
Clock Time
of Vertical
Transit over
Mean of
Horizontal
Wires.

Lamp Right or Left.

Beading of
Vertical
Circle
corrected for
liuns of
Micrometers.

Level Indication (ad-
ditive).

Barometer and • Ex-
ternal Thermometer.

"Refraction.

True observed
Zenith
Distance.

1874.
November 28

NI

Moon's L. L. ...

h in s

5. 9. 5-34

L

335. 6. 5-9

73-o

3o'n-23

if

I2O- I

0 III

65. 8.57-6

, , ...

5.21.54-56

L

33z. 15.42-5

73-o

68°- 8

106- 1

62. l8. 20-2

£ Ursse Majoris .

5. 38. 12-70

L

336. 14. 29- 1

79-3

12.6-6

66. 17. 33-6

29

NI

Rcffulus . .

5.48.37-66

6. 5p. 32-40

7. 14.42-64
7. 23. 24-08

U

11
L
U

2o5. 8.33-8

225.48.28-5
3io. 38. 39-5

23l. 20. 27- 2

63-8

70-4
7i-3
72-6

69°' i

-i°-i

n8-6

54-3
48-0
44'7

64. 52. 42-4

44. ii. 38-6
40. 40. 1 5 • 6
38. 39.28-1

t y

, ,

7- 34.49-04

I,

3o5. 59. 45-7

69-4

40-6

36. i. 12-5

Moon's L. it. ...

7.45.48-72

L

312.20. 56-5

7o-5

5i-o

42. 22. 34-8

» > ...

7. 55. 6-40

L

3io. 14. 47-6

70-6

47-3

40. 1 6. 22* 3

» » • • •

8. 2. 14-58

I,

3o8. 38. 3-7

70-6

44" 7

38. 39. 35-8

, , ...

8. 9.55-92

B

z33. 4. 19-9

71-2

42-0

36. 55. 34-1

> » ...

8. 17. 36-54

U

234.48. 2'S

70-4

3oin-24

39-4

35. 1 1, 49 -4

j » • * •

8. 25. 21 • 14

K

236. 32. 21-3

70-1

7i°-o

36-9

33. 27. 28-7

December i

HI

Moon's L. L. ...

7. 29. 36- 5o

It

199. 45. i3-o

69-0

70° -5

1 54 -i

70. 16. 34-5

, , ...

7.40. 6'3o

K

202. 6. i5-3

69-3

i36-7

67. 55. 14-5

» > ...

7. 5o. 42-14

R

204. 28. 24-8

69-4

I22"2

65. 32.5o-4

j , ...

7. 59.46-98

L

333.28. 18-7

72-4

III'7

63. 3i. 0-4

, , ...

8. 8.23-34

L

33i. 33.21-7

73-o

io3'i

61. 35.55-4

J > • • *

8. i5. 5o-52

1

329. 54. 2*2

73-'

69°- 4

96-4

59. 56. 29-3

Mars (as a star) .

8. 3o.52-6z

L

343. 7.2I-I

73-2

69° -3

182-5

73. ii. 14-4

* >

8. 39. 52-12

L

341. 6. 1-6

72-2

162-0

71. 9-33-4

O f ft

November 29. The adopted Zenith point corresponding to the mean wire is 270. o. i3'2
December i. „ „ „ 270. 0.22 -4

TABLE IX. —LONGITUDE FROM THE MOON'S OBSERVED ZENITH DISTANCE (continued). 161

Greenwich Mean
Solar Time,
assuming the West
Longitude to be

I. ioh. 3i"'.o>.
II. lo1'. 32'". os.

Tabular (1 eccentric Elements
(R. A. and N. P. D. corrected).

Hour-Angle.

Tabular Zenith
Distance of
Star or
of Limb of
Moon.

Inferred
Longitude
West of
Greenwich
lo'1. 3 1™. +

A pparent
Hight
Ascension
of Center.

Apparent
North Polar
Distance
of Center.

Equatorial
Horizontal
Parallax.

Semi-
diameter.

!, ill s

h in s

.

/ //

O f ft

0 / //

I. 23. 7.44-82

9.43. Sl-gS

71.25. 7-3

56.22-8

15.23-3

68.36.46-95

65. 8.45-0

n. 23. 8.44-65

9.43. 54-09

71. 25. 19- 1

56.22-8

15.23-3

68. 37. 18-60

65. 9. 17-0

23-6

J. 23. 20. 3I-95

9.44. 18-69

71. 27. 38-o

56. 22-4

lS.23'2

65.3i. 9-15

62.18. 7-1

II. 23.2I.3I-78

9. 44. 20-78

71.27.49-7

56. 22-4

lS.23'2

65. 3i-4o-5o

62. 18. 38-9

24'7

10. 54. 16-92

32.57- 0-6

—

—

78. 56. 10-20

66. 17. 35-5

—

•'

"

—

—

76. 19. 55-65

64. 52. 39-7

—

10. 1.42-34

77.25. 14-7

—

45. 27. 12-60

44. 11. 35"o

—

» *

, ,

—

—

41. 39. 38-70

40. 40. 1 5 • 2

—

t »

,,

—

39. 29. 16-95

38. 39.27-4

—

) t

, ,

—

—

36.38. 2-40

36. i. 10-7

—

I. 1.40. 8-28

10. 36. 57- 12

76. 58.42-6

55. 3i-9

i5. 9-4

42. 41. 48-60

42. 22. 23-5

II. 1.41. 8-09

10. 36. Sg-oS

76.58.55-6

55.31-9

i5. 9-4

42. 42. 17-25

42. 22. 54-2

22" I

I. 1.49.24-42

10. 37. 14-90

77. 0.45-2

55. 3i-6

1 5. 9-3

40. 26. 49-95

40. 16. 10-7

II. i. 5o. 24-26

10. 37. 16-80

77. 0.58-3

55. 3i-6

i5. 9-3

40. 27. 18-45

40. 1 6. 41 -o

23-o

I. i. 56. 31-44

10. 37. 28-55

77. 2.19-3

55.31-4

i5. 9-3

38.43. n-85

38.39.23-8

II. 1.57.31-28

10. 37. 30-46

77. 2.32-5

55. 3i'4

i5. 9-3

38. 43.40-50

38.39.54-5

23-4

I. 2. 4. II' 52

10. 37.43-25

77. 4. 0-8

55. 3i-2

i5. 9-2

36.5i.32-25

36. 55.17-5

11. 2. S.i'i-36

10. 37. 45- 16

77- 4- H- °

55. 3i-2

i5. 9-2

36. 52. 0-90

36. 55.48-4

32-2

1. 2. II. So-go

10. 37. 57-91

77- 5.42-I

55. 3i-o

1 5. 9-2

35. o. 2-70

35.ii. 34-1

11. 2.12.50-73

10. 37.59-83

77- 5.55-3

55. 3i-o

i5. 9-2

35. o. 3i-5o

35.12. 4-8

29-9

I. 2. 19. 34-25

10. 38. 12-70

77. 7.24-4

55. 3o-8

1 5. 9-1

33. 7.35-40

33.27. '*'9

II. 2. 20. 34-08

10. 38. 14-63

77. 7-37-6

55.3o-8

1 5. 9-1

33. 8. 4-35

33.27.44-2

3o-3

I. i. 16. 9-81

12. 3.40-77

87.55.54-2

54.28-6

14. 52-2

68.25. 2-40

70. 1 6. 17-6

II. I. 17. 9-64

12. 3.42-52

87.56. 8-2

54.28-6

14. 52-2

68.25.28-65

70. 16.47-0

34-5

I. 1.26.37-89

12. 3.59-I6

87.58.21-6

54.28-5

14. 52- 1

65. 52. n-25

67.54. 58-3

II. I.27.37-72

12. 4. 0-92

S7. 58. 35-7

54.28-5

14. 52- 1

65. 52. 37-65

67.55.28-1

32-6

I. I. 37. I2-OO

12. 4.17-74

88. o. So -5

54.28-3

14. 52-i

63. 17. 52-20

65. 32. 34-4

11. i. 38.H-83

12. 4. 19*48

88. i. 4-5

54.28-3

14. 52-i

63. 18. i«-3o

65.33. 3-9

32-5

I. 1.46.15-36

12. 4. 33-64

88. 2. 58-o

54.28-2

14. 52- 1

61. 5.37-95

63. 3o. 49-4

11. I.47- l5'2O

12. 4.35-39

88. 3. 12-1

54. 28-2

14. 52- 1

61. 6. 4-20

63. 3i. 19-1

22-2

I. 1.54. 5o-3i

12. 4.48-71

88. 4.58-9

54. 28 • i

14. 52-o

5g. o. 18-60

61.35.43-4

II. i.SS. So- iS

12. 4. 50-47

88. 5.i3-o

54.28-1

14. 52-o

59. 0.45-00

61. 36. i3-3

24-1

1. 2. 2.16-28

12. 5. 1-77

88. 6.43-6

54.27-9

14. 52-o

57. ii. 46-65

59.56. 18-2

1). 2. 3.I6-I2

12. 5. 3-52

88. 6.57-6

54.27-9

14. 52-o

S?. 12. 12-90

59.56.47-9

22-4

2. 17. 42-84

1 3. 8.41-20

95.55.57-I

o. 4-3

—

69.21. 6-45

73. ii. 19-1

—

2. 26. 40' 87

i3. 8.42-05

95. 56. 2-4

o. 4-3

—

67. 6.26-70

71. 9.37-1

—

,

162

TRANSIT OF VENUS, 1874. HONOLULU.

Day.

O

Object.

Altazimuth-
Clock Time
of Vertical
Transit over
Mean of
Horizontal
Wires.

i

o

i

«

1

Heading of
Vertical
Circle
corrected for
Kuns of
Micrometers.

Level Indication (ad-
ditive).

Barometer and Ex-
ternal Thermometer.

Refraction.

True observed
Zenith
Distance.

1874.
December i

in

Mars (as a star) .

1, III s

8.47. 56-04

R

200. 40. 47 • 7

69-2

3oin'22

146-8

69. 20. 52-3

,,

8. 55.20-26

R

202. 19. 57-3

69- 1

7i°-o

134-9

67. 41. 30-9

2

NI

Moon's L. L. ...

8.43. 3-io

R

204. 9. 34- 8

67-6

70° -9

123-7

65. 51.41-7

,,

8. 53. 24-24

R

206. 24. 22-9

•67-4

111-9

63. 36.42-0

,,

9. 2.23-12

R

208.20. 38-8

67-0

io3-i

61. 40. 17-7

j , ...

9. 12. 58-04

L

329. 21. 35-0

73-4

94-1

59. 24. 2- I

„

9. 22. 30-76

L

327. 19.48-1

73-6

3oin-23

86-9

57.22. 8-2

,,

9. 32.13-36

L

325. 16.59-3

74'4

70° -5

8o-5

55. 19. i3-8

Mars (as a star) .

9. 54. i8-52

R

214.35.24-7

67-2

80-8

55.25. 9-3

,,

10. 3. 56-12

ti

323.2i.i5-8

72-9

75-o

53.23.23-3

4

n

Mars (as a star) .

9.43. 5-52

R

211. 0. 9'7

67-4

93-0

5g. o. 36-3

, ,

9.55.32-52

I

326. 18.43-4

73-4

67°- 1

84-0

56. 21. 0-4

Moon's L. L. ...

10. 6.49-88

L

341. 47. 34-3

74-8

168-8

71. 5i. 17-5

,,

10. i5. 10-60

f.

340. 6. 12 -o

74-8

i53-7

70. 9.40-1

,,

10. 24. 27-68

L

338. 14.25-2

74-2

3o'"-i2

i39'6

68. 17. 38-6

>4

HI

10.33.35-22

R

L

L

203. 32. 32'9

320.38. 3-6

322. 2.10-3

69-4

55-5
55-6

67° -3
72°-o

127-8

67-8
7i-3

66. 28.45-9

5o. 39.46-5
52. 3.56-8

1. 17. 22-12

,,

I. 25.47-52

L

323. 32. 43-o

55-8

75-3

53.34-33-7

•

,,

1.53. 3-22

R

211. 20. II ' 3

87-3

91-2

58. 40. i3-o

, , ...

R

209. I 5. 12-2

86-1

99-0

60 45. 21 -i

December 2 to December 14, 270. o. 20-4. The observations of Mars have been used only for Zenith point.

TABLE IX. — LONGITUDE FROM THE MOON'S OBSERVED ZENITH DISTANCE (continued). 163

Greenwich Mean
Solar Time,
assuming the West
Longitude to be

I. ioh. 3 1™. os.
II. iob. 32m. os.

Tabular Geocentric Elements
(H. A. and N. P. D. corrected).

Hour-Angle.

Tabular Zenith
Distance of
Star or
of Limb of
Moon.

Inferred
Longitude
West of
Greenwich
ich. 3im. +

Apparent Apparent
Right North Polar
Ascension Distance
- of Center. of Center.

Equatorial
Horizontal
Parallax.

Semi-
diameter.

h m > h in i

0 / „

/ //

, „

o / tt

0 / 1,

•

2. 34.43-48

1 3. 8.42-80

95. 56. 7-0

o. 4-3

—

65. 5.39-00

69. 20. 54-9

—

2.42. 6-48

i3. 8.43-65

95. 56. i2-z

o. 4-3

—

63. 14.48-45

67.41.35-8

—

I. 2. 25. 3o-o5

12. 47. 39-OO

93.48.28-9

54. 10-7

14.47-3

61. 2.33-oo

65. Si. 27-9

II. 2.26.29-88

12.47.40-75

93.48.42-7

54. 10-7

14.47-3

61. 2. 59-25

65. 5i. 57-7

27-8

I. 2. 35.49-50

I2.47.57-03

93. 5o. 52-i

54. 10-6

14.47-2

58. 31.46-20

63.36.27-4

II. 2.36.49-33

I2.47.58-77

93. Si. 5-9

54. 10-6

14.47-2

58. 32. 12- 3o

63.36.56-8

29-8

I. 2.44.46-92

12.48. 12-68

93.52. 56-4

54. 10-6

14.47-2

56. 20. 57-60

61.40. 1-7

II. 2.45.46-76

12. 48. 14*42

93. 53. 10-2

54. 10-6

14.47-2

56. 21. 23-70

61.40. 3i-i

32-6

I. 2. 55. 20- 10

12. 48. 3l'I2

93. 55.22-7

54. io-5

14.47-2

53. 46. 50-40

59.23.47-5

II. 2. 56. 19-94

12.48. 3z-86

93.55. 36-5

54. io-5

14.47-2

53. 47. i6-5o

59. 24. 17-0

29-7

I. 3. 4.51-28

12.48.47-75

93.57. 34'7

54. 10-4

14.47-2

Si. 27. 48-90

57.2i.53-8

II. 3. S. Si- n

12.48.49-49

93.57.48-5

54. 10-4

14.47-2

5i.28. i5-oo

57. 22. 23-1

29-4

I. 3. 14. 32-29

12.49. 4-67

93.59.49-0

54. io-3

14.47-1

49. 6.23-55

55. 19. o-i

II. 3.15.32- 12

12.49. 6*41

94. o. 2-8

54. io-3

14.47-1

49. 6.49-65

55. 19. 29-2

28-2

3.37. 0-76

i3. ii. 4-64

96. 10.40-8

o. 4-3

—

49. 5. 5-55

55.25. n-8

—

3.46. 36- 80

i3. n. 5-54

96. 10. 46* 3

o. 4- 3

—

46. 40. 54-90

53.23.26-2

—

3. 17. 59-97

i3. i5. 34-83

96. 38. 15-4

o. 4-3

—

53. 0.20-40

59. o. 39-0

—

3. 3o. 24-92

i3. i5. 36-oo

96.38.22-5

o. 4'3

—

49. 53. Si'gS

56.21. 1-2

—

I. 3.4i.i3-53

14. 1 5. 47-20

104. 38. 15-9

54. 3-9

14.45-4

62. 7.20-40

71. Si. 0-2

II. 3.42.13-37

14. 15.49-04

104. 38. 28-1

54. 3-9

14.45-4

62. 7. 48 • oo

71. Si. 29-5

35-4

I. 3.49.32-88

14. 16. 2-67

104. 39. 57- 5

54. 4-0

14.45-4

60. 6. i-65

70. 9.22-4

II. 3.50.32-72

14. 16. 4- 52

104.40. 9-6

54. 4-0

14.43-4

60. 6.29-40

70. 9.51-7

36-2

I. 3.58.48-46

14. 16. 19*89

104. 41. 5o~4

54. 4-0

14.45-4

57.51. 3-6o

68. 17. 23-i

II. 3.59.48-30

14. 16. 21-75

104.42. 2- 5

54. 4-0

14.45-4

S?. Si. 3i-5o

68.17.52-5

3i-6

I. 4. 7. if So

14. 16. 36-82

104. 43.41-3

54. 4-0

14.45-4

55.38.24-45

66.28. 32-o

II. 4. 8.54-34

14. 16. 38-68

104. 43. 53-4

54. 4-0

14.45-4

55.38.52-35

66.29. ''3

28-4

I. 1 8. 6. 2-43

22. 41. l8'I2

IO2. 22. 32' 5

57.53-8

15.48-1

37. 9.55-8o

5o.39.55-8

II. 18. 7. 2-26

22. 41. 2O'2O

102. 22. l8'O

57.53-8

15.48-1

3y. 9.24-60

So. 39.23-4

i7-z

I. it. 14. i -ii

22.41. 34-73

102. 20. 36 -4

57.54-0

15.48-2

39. 5.46-50

52. 4. 4-9

II. 18. i5. 0-94

22. 41. 36-8o

IO2. 20. 21 "9

57- 54-0

15.48-2

39. S.iS-45

52. 3. 32-5

i5-o

I. 18.22.25-14

22.41. 52-20

102. 18. 34-1

57.54-2

15.48-2

41. 7.45-60

53. 34.44-2

II. 18.23.24-98

22. 41. 54-27

102. 18. 19-6

57.54-2

15.48-2

41. 7. 14- 55

53.34. ii -5

i9-3

I. 18.49. 36-40

22.42.48-74

102. II. 57-8

57.54-9

i5.4S-4

47.42. 33 -3o

58.40. 26-5

II. 18. So. 36-23

22.41.50-83

102. II. 43*2

57.54-9

15.48-4

47.42. i-95

58.39-53-0

24-2

I. 19. 0.25-66

22. 43. II-24

IO2. 9. 19*8

57.55-1

15.48-5

So. 18. 26-25

60.45. 3i- 8

II. 19. 1.25-49

22.43. 13-33

I O2. 9. 5 "2

57.55-1

15.48-5

5o. 17. 54-90

60. 44. 58-2

19-1

December 14. The aperture was slightly reduced.

164

TRANSIT OF VENUS, 1874. HONOLULU.

Day.

Observer.

Object.

Altazimuth-
Clock Time
of Vertical
Transit over
Mean of
Horizontal
Wires.

1

3
'S

1

fv*

I

Heading of
Vertical
Circle
corrected for
Runs of
Micrometers.

Level Indication (ad-
ditive).

Barometer arid Ex-
ternal Thermometer.

Hefractioii.

True observed
Zenith
Distance.

1874.
December 14

i5

SI

HI

Moon's L. L. ...
(3 Ceti .

li m s
2. II. 3S-4O

2. 2O. 44- 12
2. 3o. 12' 2O

2. I8.28-66

K

It
I,

L

o / //

207.43. 40-6

222. 36. 2O- 2

3i8. 38.59-2
319.59. 8-1

a
85-9

86-6
54-o

Sg-o

3o""20

7i°-9
66° -8

a
io5'S

60 • 3
63-2

66-9

0 / //

62. 1 6. 59-4

47.23.34-1
48. 40. 36 *o

5o. o. 53-6

Moon's L. L. ...

, , ...

2. 26.45-52

(

321.37. 16-5

59-3

70-9

5i.39. 6-3

, , ...

2.44. 36-12

L

325.13. 1-8

59-8

80-9

55.i5. 2-1

, , ...

2.53.48-48

II

212. Si. 57-4

85-6

86-8

57. 8.24-2

, , ...

3. 3.44-06

R

210.48. 25'4

83-7

94-0

59.12. 5-3

18

m

/3 Ceti

3. 14.43-24

3.24.43-54
3.34.53-02

4.43. 11-42

n

•

L
I,

208. 3o. 16-8

212.39.37-7
329. 7. i-3

307.58. 7-1

83'4

84-6
56-2

60-2

65°'9

30""20

66° -5

I03'2

87-5
93-8

43-6

61. 3o. 23-4

57. 20. 45-6
59. 9. 10-9

37.59.26-5

Moon's L. L. ...

, , ...

4. 5o. 24-08

L

3o9.35.35-5

60-6

7i°-i

46-2

39.36.57-9

,,

5. n. 19-90

L

314. 18.46-1

60-9

54-5

44. 20. 17-1

,,

5. 20. 59-84

R

223. 28.49-9

81-2

58-7

46. 3i. 12 -o

, , ...

5. 3o. 12-96

R

221.24. 3'7

80-0

3oin-i7

63-2

48.36. 3-9

19

jji

5.39.44-74

6. 7.24-12
6.16. 0-68

5.24. i5-i8

R

K
t,

L

219. i5. 18-2

212. 59. 53-2

328.54.57-5

302.38. 6-7

79-6

77'o
64-5

62-4

7i"-o
65°- 5

68-2

85-7
92-4

36-o

5o. 44. $4-8

57. 0.39-9
58.57. 10-0

3z. 39. 20- 7

MOOD'S L. L. ...

,,

5.32. 7-48

L

3O4. 24. 42 • 2

62-0

38-5

34.25. 58-3

0 f If

December i5. The adopted Zenith point corresponding to the mean wire is 270. o. 20-4
December 1 8. „ „ „ 270.0.24-4
December 19. „ „ „ 270.0.24-4

TABLE IX. — LONGITUDE FROM THE MOON'S OBSERVED ZENITH DISTANCE (continued). 165

Greenwich Mean
Solar Time,
assuming the West
Longitude to he
I. ioh. 3im. o".

II. I0h. 32"'. 0s.

Tabular Geocentric Elements
(K. A. and N. P. D. corrected).

Hour-Angle.

Tabular Zenith
Distance of
Star or
of Limb of
Moon.

Inferred
Longitude
West of
Greenwich
ioh. 3 11". +

Apparent
Right
Ascension
of Center.

Apparent
North Polar
Distance
of Center.

Equatorial
Horizontal
Parallax.

Semi-
diameter.

h til s

h la a

0 f ft

/ //

/ //

0 / //

o / //

K

I. 19. 8. 5-56

22.43.27-I8

102. 7.27-8

57.55-3

15.48-5

52.10.59-55

62. 17. II -2

II. 19. 9. 5-39

22.43. 29-27

IO2. 7. 1 3'2

57.55-3

15.48-5

52. 10. 28-20

6z. 16.37-5

21-0

o. 37. 18-82

108.40. 3i'i

—

—

26. o. 15-90

47.23.32-9

—

» »

'

—

—

28. 22. I7-25

48. 40. 34- 5

—

I. 19. ii. 2-41

23.32.59-88

95.58.23-8

58.3i-o

15.58-3

41. 3i. 17-70

5o. i. 6-5

11. 19. 12. 2-24

23.33. 1-93

95.58. 7-9

58.3i-o

iS.58-3

41. 3o. 46-95

5o. o.32-5

22-8

I. 19.19.17-93

23.33. 16-81

95. 56. 11-9

58. 3i-2

i5. 58-3

43. 3 1. 16-80

51.39.17-3

II. 19. 2O. I7'76

23.33. i8-85

95.55.56-o

58.3i-2

15.58-3

43. 3o. 46-20

5i.38. 43-2

19-4

I. 19. 37. .5- 60

23.33.53-26

95. 5i. 27-6

58. 3i-6

15.58-5

47.49.49-05

55. i5. 14-7

II. 19.38. 5-44

23.33.55-31

95. 5i. 11-7

58. 3i-6

iS.58-5

47. 49. 18- 3o

55. 14. 40-5

22-1

I. 19.46. 16-45

23.34. IZ'°8

95.49. 0-8

58. 31-9

iS.58-5

5o. 3. i2-i5

57. 8.41-6

II. 19. 47. 16-29

23. 34. 14- 12

95.48.44-9

58.3i-9

iS.58-5

5o. 2.41-55

57. 8. 7-3

3o'4

I. 19. 56. 10-42

23. 34. 32-36

95.46. 22- 5

58. 32-i

15.58-6

52.27. i'8°

59. 12. 2O'9

II. 19. 57. io-z5

23. 34. 34-40

95.46. 6'- 6

58.32-1

iS.58-6

52. 26. 3i-zo

59. 11.46-6

27-3

I. 20. 7. 7-79

23. 34.54-81

95.43.27-2

58. 32-4

iS.58-7

55. 6.12-75

61. 3o. 37-9

II. 20. 8. 7-63

23. 34. 56-85

95.43. ii -3

58. 32-4

i5. 58-7 ,

55. 5.42-15

61. 3o. 3-6

25-4

o. 37. 18-80

108.40. 3i- 1

—

—

42. o. 17-40

57. 20.44-3

—

"

"

—

—

44. 32. 39-75

5g. 9. 9-1

—

I. 21.23.35-75

2. 10. 3o-66

75. 50.43-4

60. 5-i

1 6. 24-0

38. 19.47-70

37-59.47-4

II. 21.24.35-58

2. 10. 32-93

75. 5o.28-3

60. 5-i

1 6. 24-0

38. 19. i3-65

37.59.11-5

34-9

1. 21. 30.47-23

2. 10.47-06

75.48.54-3

60. 5-2

16. 24-0

40. 3. 5i-6o

39.37.17-9

II. 2I.3I.47-06

2. 10. 59-34

75.48.39-2

60. 5-2

1 6. 24-0

40. 3. 17-40

39. 36.41-9

33-3

I. 2I.5l.39'63

2. II. 34-68

75.43.38-o

60. 5-5

16. 24- 1

45. 5.54-75

44. 20. 37-0

II. 2I.52.39-47

2. II. 36-96

75.43.22-9

60. 5-5

1 6. 24- 1

45. 5.20-55

44. 20. i *o

33-2

I. 22. I. 17-99

2. II. 56-70

75.41. I2-I

60. 5-6

16. 24-2

47.25.23-55

46. 3 1. 29-0

II. 22. 2.17-83

2. II. 58^8

75.40. 57-0

60. 5-6

16. 24-2

47.24.49-35

46. 3o. 52-9

28-2

I. 22. IO. 29-61

2. 12. 17-70

75.38.53-i

60. 5-7

16. 24-2

49. 38.25-5o

48. 36. 16-0

II. 22. ii. -y'44

2. 12. 19-98

75.38.38-o

60. 5-7

16. 24-2

49. 37. 5i-3o

48.35.40-1

20-2

I. 22.19.59-83

2. 12. 39*41

75.36.29-5

60. 5-9

16. 24-2

5i. 55. 56-55

5o-45. ii- 1

II. 22. 2O. 59-66

2. 12. 41-70

75. 36. 14-4

60. 5-9

1 6. 24-2

Si. 55. 22'20

5o. 44. 35'o

27-1

2. 0. 7-79

67. 7.39-0

—

—

61. 58.42-00

57. 0.38-3

—

"

» >

—

—

64. 7. So-io

58.57. n-2

—

I. 22. O. 37-48

3. 8.40-93

70. 4. 10-7

60. 19*9

16. 28-0

34. 3.I9-35

32.39. 36-2

•

II. 22. 1.37-32

3. 8.43-39

70. 3.58-o

60. 19-9

16.28-0

34. 2.42-45

32.39. o-i

25-8

I. 22. 8.28-49

3. 9. o-i5

70. 2. 3o-5

60. 19-9

1 6. 28-0

35. 56.35-55

34. 26. ii -o

II. 22. 9.28-32

3. 9. 2-61

70. 2. 17-8

60. 19-9

16.28-0

35.55.58-65

34.25.34-5

20-9

v 2

166

TRANSIT OF VENUS, 1874. HONOLULU.

Day.

Observer.

Object.

Altazimuth-
Clock Time
of Vertical
Transit over
Mean of
Horizontal
Wires.

i

d

4

s
p.

3

Reading of
Vertical
Circle
corrected for
Runs of
Micrometers.

Level Indication (ad-
ditive).

Barometer and Ex-
ternal Thermometer.

Refraction.

True observed
Zenith
Distance.

1874.
December 19

SI

Moon's L. L. ...

li ra s

5. 38. 40-74

L
R

3o5. 53. 16-1
23i. 10. 59-5

62-4
81-0

65°-5

40-7
45-2

35. 54. 34-8
38. 48. 49' i

, , ...

5. 5 1. 34-74

,,

5.59.47-44

K

229. 20. 20-9

80-6

48* 2

40. 39. 3i-i

20

NI

» > ...
o Tauri

"6. 7. 5-34

6. 20. 5«' 08
6.28. 52-74

7. 22. 58-90

R

K
Ii

L

227.42. 8-5

242. 52. i5-i
298.57.42-7

314.23.47-4

79'5

80-9

58-5

64-4

3oin-o9
66° -I

60° -4

5i-i

28-8
3i-i

55-5

42. 17. 47- 5

27. 7.17-2
28. 58.47-9

44. 25. 21-9

Moon's L. L. ...

7.33.15-32

L

3i6. 38. 22-5

64-6

59-9

46. 40. i • 6

, , ...

7.43. 31-94

I,

3i8. 52.46-4

64-6

3oin-o7

64-8

48. 54. 3o-4

|

j j ...

7.57. ii-56

K

218. 7.40-9

81-6

63°- 1

71-8

5i.52. 34-7

...

8.36.59-16

K

209.33. 6-1

80-2

99-1

60.27. 38-2

, , ...

8. 44. 52*40

R

207. Si. 55-8

80-2

106- i

62. 8.55-5

21

NI

Moon's L. L. . . .

7.52.17-38

R

233. 56.41-4

79-8

59° -o

4i-3

36. 3. 6-5

, , . . .

7.59.46-14

R

232.20. l5'3

80-4

43-7

37.39.34-4

, , . . .

8. 7.58-96

R

z3o. 34.26-6

8o-3

46-6

39. 25. 26-1

, , . . .

8. 19.29-34

L

3n. 52. 8-9

63-o

5o-7.

41.53. 36-2

, , . . .

8.26.53-I8

t

3i3. 27. 16-0

66-6

3oin • oo

53-6

43.28.46-8

» > . . .

8. 34.20-38

L

3i5. 3. 2-3

63-5

6i°-7

56-6

45. 4.36-0

7 Geininorum . . .

8. 58. 24-14

L

3o5. 21.49-3

58-8

40' i

35.23. 1-8

, , . . .

9. 6.54-64

R

232. 37.48-4

85-8

43-i

37.21.54-3

, , . . .

9. 18. 13-90

L

309. 58.49-3

58-4

47 '4

40. o. 8-7

. O f If

December 20. The adopted Zenith point corresponding to the mean wire is 270. o. 25-4
December 21. „ „ „ 270.0.26-4

TABLE IX. — LONGITUDE FROM THE MOON'S OBSERVED ZENITH DISTANCE (continued}. 167

Greenwich Mean
Solar Time,

Tabular Geocentric Elements
(B. A. and N. P. D. corrected).

Tabular Zenith
Distance of

Inferred
Longitude

assuming the West
Longitude to be
I. ioh. 3im. os.

II. I0h. 32'". 0s.

Apparent
Right
Ascension
of Center.

Apparent
North Polar
Distance
of Center.

Equatorial
Horizontal
Parallax.

Semi-
diameter.

Hour-Angle.

Star or
of Limb of
Moon.

West of
Greenwich
ioh. 3 1". +

h in !

h m s

0 / t/

/ //

/ //

Off,

o / //

s

I. 22.15. 0-68

3. 9. 16- 17

jo. i. 7-2

60. 20 -o

1 6. 28-1

37. 3o. 54-30

35.54. 5o-4

II. 22. 16. 0-52

3. 9.18-63

70. o. 54-5

60. 20-0

16. 28-1

37. 3o. 17 -40

35. 54. 14-1

25-8

I. 22. 27. 52-57

3. 9. 47 -74

69.58.23-4

60. 20 -o

16.28-1

40. 36. 3o'75

38.49. 3-5

II. 22.28.52-4I

3. 9. 5o-i8

69. 58. 10-7

60. 20 -o

16.28-1

40. 35. 54- 1 5

38.48.27-4

23-9

I. 12.36. 3-93

3. 10. 7-81

69. 56.39-4

60. 2O ' I

16.28-1

42. 34.40*20

40.39.47-0

II. 22.37. 3-77

3. 10. 10-26

69. 56. 26-7

60. 2O- I

16.28-1

42. 34. 3-45

40. 39. 10-7

26-3

I. 22.43.20-64

3. 10. 25-69

69.55. 7-0

60. 2O- I

16.28-1

44.19.40-65

42.18. 2-8

II. 22.44.20-48

3. 10.28-14

69. 54. 54-3

60. 20-1

16.28-1

44.19. 3-90

42.17.26-7

25-4

4. 28. 45 • 64

73.44.29-9

—

—

28. II. 22' 5o

27. 7. 17-0

—

"

»

—

3o. ii. 32-40

28. 58.45-3

—

I. 23. 55. 6' 53

4. 14. 3i-63

65. 20. 20 -o

60. zo-6

16.28-2

47. i6.45-i5

44.25.36-3

II. 23.56. 6-37

4. 14. 34-25

65. 20. ii- 1

60. 20 -6

16. 28-2

47.16. 5-85

44.24. 59-6

23-5

I. o. 5.21-27

4. 14. 58- 5i

65. 18.47-1

60. 20 -6

16.28-2

49.44. 8-25

46.40. 18-6

II. O. 6. 21 -II

4. 1 5. i-i3

65. 18. 38-2

60. 20 - 6

16. 28-2

49.43. 28-95

46.39.42-1

28-0

I. o. i5. 36-20

4. 1 5. 25-46

65. 17. 16-1

60. 20-5

16.28-2

52. ii. 33-3o

48. 54. 44- o

II. o. 1 6. 36-04

4. 15.28-08

65.17. 7-*

60. 20-5

16.28-2

52. 10. 54-00

48.54. 7-6

22-4

I. o. 29. i3'6o

4. 1 6. 1-29

65.15. i5-6

60. 20-5

16.28-2

55. 27. 3o-3o

5i.52. 53-4

II. o. 3o. 13-44

4. 16. 3-91

65.i5. 6-8

60. 20-5

16.28-2

55. 26. Si'oo

Si. 52. 17-0

3o-8

I. I. 8.54-68

4- '7- 45'77

65. 9.27-8

60. 20-2

16.28-1

64. 58. 17-10

60. 27. 55-o

II. I. 9.54-52

4. 17.48-41

65. 9. 19-1

60. 2O • 2

16. 28-1

64. 57. 37 -So

60. 27. 18-0

27-0

I. i.i6.46-63

4. 1 8. 6-49

65. 8.19-4

60. 2O '2

16. 28-1

66. 5i. 24-90

62. 9. 12-7

II. 1.17.46-47

4. 1 8. 9-14

65. 8. 10-7

60. 2O ' 2

16.28-1

66.5o.45-i5

62. 8.35-6

27-8

I. o. 20. 24-76

5. 20. 9-66

62. 37. 27-1

60. 5-8

16. 24-2

38.H.58-80

36. 3.23-6

II. 0.21.24-60

5.10. 12-39

62.37.22-8

60. 5-8

1 6. 24-2

38.ii. 17-85

36. 2.47-3

28-1

I. 0.27.52-30

5. 20. 3o-o5

62.36.55-i

60. 5-7

16.24-1

39.59. 4-35

37.39.49-7

II. 0.28.52-14

5. 20. 32-77

62. 36. 5o-9

60. 5-7

1 6. 24-2

39.58.23-55

37.39. i3-6

25-4

I. o.36. 3-78

5. 20. 52-42

62.36.2o-3

60. 5-6

16. 24-2

41. 56.41-25

39. 25.42-2

II. 0.37. 3-62

5. 20. 55- 15

62. 36. 16-0

60. 5-6

16. 24- 2

41.56. o-3o

39.i5. 5-9

16-6

I. 0.47.32-28

5.21.23-78

62. 35. 3i-8

60. 5 • 4

16. 24-1

44.41.26-70

41. 53. 54-0

II. 0.48.32-12

5. 21. 26'Sl

62.35.27-6

60. 5-4

16. 24' i

44.40.45-75

41.53.17-5

29-3

I. o. 54. 54-92

5. 21.43-95

62. 35. 0-9

60. 5-3

16. 24- 1

46.27.21-75

43.29. 4-4

II. 0.55.54-75

5.21.46-68

62.34.56-7

60. 5-3

16. 24- 1

46. 26. 40-80

43.18.27-8

28-8

I. i. 2.20-91

5.22. 4-27

62. 34. 29-9

60. 5-2

16. 24*0

48. 14. 5"io

45. 4.52-3

II. i. 3.20-74

5.22. 7"OO

62.34.25-8

60. 5-2

16.24-0

48. i3. 24-15

45. 4. 16-0

26- 9

6. 3o. 30-27

73.29. 38-i

—

—

37. 8. 3i-8o

35.23. 3-o

—

, »

, ,

—

—

39. 16. 9-45

37.21.56-8

—

» j

"

—

—

42. 5.58-5o

40. o. 9-8

—

168

TRANSIT OF VENUS, 1874. HONOLULU.

Day.

Observer.

Object.

Altazimuth-
Clock Time
of Vertical
Transit over
Mean of
Horizontal
Wires.

<K
a)
i-3

i*
O

|

a

O.

•
1?

Reading of
Vertical
Circle
corrected for
Runs of
Micrometers.

Level Indication (ad-
ditive).

Barometer and Ex-
ternal Thermometer.

Refraction.

True observed
Zenith
Distance.

1874.
December 12

T

Moon's U. L, . .

1) ni s

4- 3. 4'74

L

3oo. 45. 40* 9

n
9I-3

60° -o

//
33-6

0 / //

30.47. 19-4

, , L. L. . .

4. 5.40-82

L

300.45.40-9

9I-3

29 ""94

33-6

30.47. 19-4

, , U. L. . .

4- H-39'74

L

298.18. 8-6

91-4

30-4

28. 19.44-0

, , L. L. . .
, , U. L. . .

4. 17. 16-62
4. 23. 3l'q8

I,
L
L

298.18. 8-6
296.25. 35-8
296.25.35-8

91-4
91-6

91 -6

3o~4

28-0
28-0

28. 19. 44'o
26.27. 9-0
26. 27. 9-0

, , L. L. . . .

4.26. 9-28

, , U. L. . . .

4.33. 9-90

R

245. 34.41-0

53-o

25-6

24. 25. i8~o

, , L. L. . . .

4.35.48-06

R

245. 34.41-0

53-o

25-6

24. 25. 18-0

, , U. L. . . .

4.42. 52 '12

K

247. 36. 34-0

5i-5

23-2

22. 23. 24-1

, , L. L. . . .

4.45. 30-84

R

247. 36. 34-0

5i-5

23-2

22. 23. 24' I

, , U. L. . . .

5. 0.25-74

R

25i. 14. 24-2

5o-6

29iD193

19-1

18.45. 3o-y

24

NI

, , L. L. . . .
Moon's L L. .

5. 3. 7-78
4. 35 42* 06

H

K
R

25i. 14. 24-2

217.17. 2-7
218. 54.26-6

5o-6

55-4
55-5

60° -8

59°-o

19-1

74' 2

70-0

18.45. 3o-7

52.43.42-5
5i. 6. 14-3

4. 43. io- 56

,,

4.49.42-74

R

220. 20. o- 5

55-5

66-5

49. 40. 36-9

, , ...

4. 58.26-42

L

317.44. 2-6

87-9

62-2

47.46. 6-3

, , ...

5. 6.31-72

L

3i5. 57.49-4

88-5

3oin'oo

58-5

45. 5g. 5o-o

, , ...

5. 13.41-30

L

314.23.34-5

88-8

59°-5

55-3

44. 25. 32-2

o / //

December 22. The adopted Zenith point corresponding to the mean wire is 270. o. 26-4
December 24. „ „ „ 270.0.26-4

TABLE IX. — LONGITUDE FROM THE MOON'S OBSERVED ZENITH DISTANCE (continued). 169

Greenwich Mean
Solar Time,
assuming the West
Longitude to be
I. ioh. 3 1"1. os.

II. J0h. 32™. 0".

Tabular Geocentric Elements
(R. A. and N. 1'. D. corrected).

Hour-Angle.

Tabular Zenith
Distance of
Star or
of Limb of
Moon.

Inferred
Longitude
. West of
Greenwich
ioh. 3 1™. +

Apparent
Right
Ascension
of Center.

Apparent
North Polar
Distance
of Center.

Equatorial
Horizontal
Parallax.

Semi-
diameter.

li m s

b in s

/ //

0 ' / //

_

a

1. 20. 27. 54' OO

6. i5. 19-03

61. 52.27-5

59.42-5

16.17-9

32.53.27-75

30.47. 11-9

II. 20.28.53-84

6. i5.2I-75

61. 52. 27-4

59.42-5

16. 17-9

32. 54. 8-55

30.47.47-7

12-6

I. 20. 3o. 29' 65

6. i5. 26-13

61. 52. 27-0

59.42-4

16. 17-8

32. 16. i3-o5

30.47. 6-5

11. 20. 3i. 29-48

6. i5.28-85

61.52. 26-9

59.42-4

16. 17-8

32. 16.53-85

30.47.42-2

21-7

I. 20. 39. 27-09

6. i5. 5o-6i

61. 52.25-8

59.42-2

16. 17-8

3o. 7. 36-45

28.19.36-5

II. 20.40.26-93

6. i5. 53-34

61.52. 25-7

59.42-2

16. 17-8

3o. 8. 17-40

28. 20. 12-4

12-5

]. 20.42. 3-55

6. 1 5. 57-74

61. 52.25-5

59.42-2

16. 17-8

29. 3o. 10-20

28. 19.27-8

II. 20.43. 3-38

6. 1 6. 0-47

6i.5Z. 25 -,3

39.42-2

1 6. 17-8

29. 3o. 5i-i5

28.20. 3-8

26-9

1. 20.48.17-88

6. 16. 14-81

61. 52. 24-8

59.42-0

16.17-7

28. o. 35-85

26.26.57-3

II. 20.49. '7'72

6. 1 6. 17-54

61. 52.24-7

59.42-0

16.17-7

28. 1.16-80

26. 27. 33-i

19-6

I. 20. 5o. 54-75

6. 16. 21 -96

61. 52. 24-5

59. 42-0

16. 17-7

27.23. 3-6o

26. 26. Si' i

II. 20. 5i. 54-59

6. 16.24-68

61. 52. 24-4

59.42-0

16. 17-7

27.23.44-40

26. 27. 26-6

3o-2

I. 20. 57. 54-22

6. 16.41 -07

61. 52. 23-9

59.41-8

16. 17-7

25.42.40-95

24.25. 8-9

II. 20.58.54-06

6. 16.43-80

61. 52. 23-9

59.41-8

16.17-7

25.43. 21-90

24.25.44-4

i5-4

1. 21. 0. 31-gS

6. 16.48-26

61. 52.23-8

59.41-8

16. 17-7

25. 4.56-40

24. 25. 2-9

II. 21. i. 31-79

6. 16. 5o-g8

61. 52.23-7

59.41-8

16.17-7

25. 5. 37-20

24.25. 38-i

25-7

I. 21. 7.34-86

6.17. 7-53

61. 52. 23-4

59.41-6

16. 17-6

23.23.44-55

22. 23. I0'5

II. 21. 8.34-69

6. 17. io-25

61. 52. 23-4

59.41 -6

16. 17-6

23.24.25-35

22.23.45-2

23-5

I. 21. io. i3-i5

6. 1.7. 14-74

61. 52. 23-4

59.41-5

16. 17-6

22.45. Si'-go

22. 23. I2'4

II. 21. H. 12-98

6. 17. 17-47

61. 52. 23-3

59.41-5

16. 17-6

22.46. 32-85

22. 23.47-O

20-3

I. 21.25. 5-60

6. 17. 55-40

61. 52.23-3

59.41-2

16.17-5

19. 12. 18- 3o

i8.45. i6-3

II. 21.26. 5-43

6. 17. 58-iz

61. 52.23-3

59.41-2

16. 17-5

19. 12. 59- io

18.45. 50-7

25-1

I. 2I.27.47-20

6.18. 2-76

61. 52. 23-4

59.41-1

16.17-5

18. 33. 38-io

18.45.20-5

11. 21.28.47-04

6.18. 5-48

61. 52. 23-4

59.41-1

16. 17-5

1 8. 34. 18-90

i8.45.54-7

17-9

1. 20.52.35-70

8. 22. 0-24

65.24.46-8

58.15-9

i5. 54-2

56. 24. 2-55

52.43.26-1

II. 20.53.35-54

8.22. 2-68

65.24. 55-2-

58. 15-9

15.54-2

56.24. 39-15

52.44. 0-2

28-9

I. 21. O. 2-09

8.22. I8-43

65.25.49-3

58. i5-6

i5.54-i

54. 36.41 -40

Si. 5.56-0

II. 21. I. 1-92

8.22.20-86

65.25. 57-7

58.15-6

15.54-1

54.37. 17-85

Si. 6.3o-i

32-2

I. 21. 6.33-35

8.22.34-36

65. 26. 44-2

58.15-4

i5. 54-0

53. 2.37-65

49. 40. 21 ' I

II. 21. 7.33-19

8.22. 36 -80

65.26.52-6

58. 15-4

i5. 54-0

53. 3.14-25

49. 40. 55-2

27-8

I. 21. IS. l5'45

8.22. 55 -61

65.27. 57-6

58-iS-i

i5. 54-0

So. 57. i -20

47.45. 5i-3

II. 21.16.15-28

8.22. 58-o5

65.28. 6-0

58. i5-i

i5. 54-0

5o. 57. 37-80

47.46.25-4

26-4

I. 21. 23. I9'42

8.23. i5-3o

65.29. 5-8

58. 14-8

15.53-9

49. o, 36 - 90

45. Sg. 32-o

II. 21. 24. 19-26

8.23.17-74

65. 29. 14-2

58. 14-8

iS.53-9

49. i. i3-5o

46. o. 6-0

3i-8

I. 21. 3o. 27-84

8.23. 32-73

65. 3o. 6-3

58. 14-6

15.53-8

47. 17.34-65

44.25. 15-9

II. 2I.3I.27-67

8.23.35-16

65. 3o. 14-7

58. 14-6

i5. 53-8

47. 1 8. ii -10

44.25.49-8

28-8

December 22. Cloudy. Aperture reduced for some of the observations.

170

TRANSIT OF VENUS, 1874. HONOLULU.

Day.

Observer.

Object.

Altazimuth-
Clock Time
of Vertical
Transit over
Mean of
Horizontal
Wires.

4

S

d

I
g,

Reading of
Vertical
Circle
corrected for
Runs of
Micrometers.

Level Indication (ad-
ditive).

Barometer and Ex-
ternal Thermometer.

Refraction.

True observed
Zenith
Distance.

1874.
December 26

NI

Moon's L. L. ...

h m s

6. 49. 12 - 44

L

3ig. 3o. 36-9

82-6

67° -i

65-5

o / //

49. 32. 3g-6

"

6.57.35-78

L

317. 36. 42-2

82-2

68° -o

61-2

47. 38.40-2

7. 10.41-30

L

314. 38.46-0

81-6

3oin-o8

55-2

44.40. 37-4

,,

7.20. 9-32

R

227. 28. 29-4

62-4

5l'2

42. 31.44-8

"

7. 3o. 45 • 74

R

229. 52.46-6

62-3

47-1

40. 7.23-6

29

NI

7. 38. 57-00

8. 8.20-64
8. 18. i3-i6

7. 3o. 53-24

R

R
L

L

231.44. 9'2

228. 34. 36-6
3og. 7.17-9

347. 3.J2-8

62-3

60-0
81-6

77'7

68° -2

67° -8

63°-4

44-1

49-3
45-5

240-3

38. i5. 58-o

41.25. 38-i
39. 8.59-6

77- S. 3-4

Moon's L. L. ...

, j ...

7.39.47-02

L

345. 4.28-8

77-6

208-4

75. 8.47-4

7. So. i-36

L

342.47.59-2

78-2

63°- 1

180-2

72- 5i. 5o-2

,,

8. o. 19-46

R

199. 27. 3i-2

66-7

i58-o

70.34.27-5

,,

8. 10. 17-66

R

201. 39. 5o'9

66-6

30-09

140-8

68.21. 50-7

„

8. 18. 34-60

R

203.29.28-8

66-2

63°- 5

128-8

66.32. 1-2

3o

NI

Moon's L. L. ...

9.19. 4-72

L

335.19.28-6

76-8

65°-o

121-8

65.22. 19-8

,,

9. 27. 36-70

Si

333. 3i. 3o-3

76-9

II2-5

63. 34. 12- 3

9. 36. 12-82

9.44. 29-68
. 9.53.21-70
10. 3.35-84

L

L
R
R

33i.43.26-8

33i. 13.53-7
210. 35. i8-3
2i3. 52. 24-1

76-9

76-4
68-9
67-6

64° -2

104-4

102- 3

94' 9
83-7

61.46. 0-7

61. 16. 25-0
59. 25. 35-i
56. 8.19-4

Moon's I .. 1 .. ...

o / //

December 26. The adopted Zenith point corresponding to the mean wire is 270. o. 25-4
December 29 and December 3o. The adopted Zenith point corresponding to the mean wire is 270°. o'. 27" -4

TABLE IX. — LONGITUDE FROM THE MOON'S OBSERVED ZENITH DISTANCE (continued). 171

Greenwich Mean
Solar Time,
assuming the West
Longitude to be
I. ioh. 3 1"'. os.
II. ioh. 82'". o".

Tabular Geocentric Elements
(R. A. and N. P. D. corrected).

Hour-Angle.

Tabular Zenith
Distance of
Star or
of Limb of
Moon.

Inferred
Longitude
West of
Greenwich

ioh. 3im. -t-

Apparent
Kight
Ascension
of Center.

Apparent
North Polar
Distance
of Center.

Equatorial
Horizontal
Parallax.

Semi-
diameter.

h in s

h m s

0 / //

0 / //

o / //

s

I. 22. 57. 52-00

10. 13.49-76

74.39.42-7

56.3o-i

iS.25-3

5o.58. 55 -5o

49. 32.22-9

II. 22.58.51-84

10. 1 3. 51-79

74.39.55-7

56.3o-i

15.25-3

5o. 59. 25-95

49.32.54-7

3i-5

I. 23. 6.13-97

10. 14. 6-79

74.41.31-9

56.29-8

15.25-2

48.57.20-85

47. 38.23-0

II. 23. 7. i3-8i

10. 14. 8-81

74.41.44-9

56.29-8

15.25-2

48.57.5i-i5

47. 38. 54-6

32-7

I. 23.19.17-35

10. 14. 33-34

74.44.22-4

56. 29-4

iS.25-1

45.47. 36- 3o

44.40. 19-1

II. 23. 20. 17-19

10. 14. 35-37

74.44.35-5

56. 29-4

i5.25-i

45.48. 6-75

44. 40. 5 1 * o

34-4

I. 23.28.43-82

10. 14. 52-53

74.46.25-9

56.29-0

i5.25-o

43. 30.23-70

42. 3i.28-8

II. 23.29.43-66

10. 14. 54- 56

74.46.38-9

56.29-0

i5. 25-o

43. 3o. 54T5

42.32. 0-6

3o-2

I. 23.39.I8-50

10. i5. 14-02

74.48.44-2

56.28-7

15.24-9

40. 56. 39-75

40. 7. 6-2

II. 23.40.I8-34

10. i5. i6-o5

74.48.57-3

56.28-7

15.24-9

4O. 57. IO"2O

40. 7.38-0

32-8

I. 23.47.28-42

10. 1 5. 3o-6o

74. 5o. 3i-i

56.28-4

15.24-8

33.57.59-55

38. 15.40-5

II. 23.48.28-26

10. 1 5. 32-62

74.50.44-2

56.28-4

1 5. 24-8

38.58.29-85

38. 16. 12-1

33-2

ii. 7.27-74

68.47. 33-9

—

—

44. 36. 22-o5

41.25. 37-2

—

»

"

—

—

42. 8. 14-25

39. 8.58-6

—

I. 23.27.38-99

12. 28.48-84

91.34. 0-7

54-36-8

14. 54-4

74. 1 8. i8-3o

77- 7- 48' I

II. 23.28.38-83

12. 28. 5o-6o

91. 34. 14-8

54. 36 • 8

14.54-4

74.18.44-70

.77- 8-»7-9

3o-8

I. 23.36.31-32

12.29. 4-48

91. 36. 6-1

54.36-7

14. 54-4

72. 8.46-20

75. 8.34-2

II. 23. 37. 3i-i5

12.29. 6-24

91. 36. 20-2

54.36-7

14.54-4

72. 9. 12-60

75. 9. 4-0

26-6

I. 23.46.43-97

12. 29. 22-49

91. 38. 30-4

54. 36-5

14.54-4

69. 39.41-40

72. Si. 37-1

II. 23.47.43-81

12. 29. 24-25

91. 38.44-5

54.36-5

14.54-4

f 69.40. 7-80

72. 52. 6-9

26-4

I. 23.57. o-38

12. 29. 40-60

91.40. 55-6

54.36-4

14.54-3

67. 9.41-55

70. 34. 10-7

II. 23.58. 0-21

12. 29. 42-36

91.41. 9-7

54.36-4

14.54-3

67.10. 7-95

70. 34.40-5

33-8

I. o. 6.56-95

12.29. 58-i8

91.43. 17-2

54. 36-2

14.54-3

64.44. 32-25

68.2i.35-o

II. o. 7.56-79

12.29.59-94

91.43. 3i-3

54.36-2

14.54-3

64.44. 58-65

68.22. 4-8

3i-6

I. o. i5. 12- 52

12. 3o. 12-75

91.45. 13-9

54.36-1

14. 54-2

62.43. 56-85

66.3i.46-3

II. 0.16.12-35

12. 3o. 14- 5o

91.45. 28-0

54. 36-i

14. 54-2

62. 44. 23 - 10

66. 32. 16-0

3o-i

I. 1.11.37-43

1 3. 14. 11-99

97. 3i. 20-0

54.I7-5

14.49-1

58.36. 4-50

65.22. 3-8

II. 1.12.37-26

1 3. 14. 13-76

97. 3i.33-5

54.I7-5

14.49-1

58. 36. 3i-o5

65.22.33-4

32-4

I. 1.20. 7-99

1 3. 14. 27-07

97.33. i5-4

54.17-4

14.49-1

56.3i. Si-iS

63.33.56-5

ii. i. 21. r83

13.14.28-85

97. 33. 28-9

54.17-4

14.49-1

56.32. i7-85

63.34.26-2

Si-S

I. 1.28.42-69

1 3. 14. 42-28

97. 35. n-6

54.I7-3

14.49-1

54.26. 37-80

61.45.46-8

II. 1.29.42-53

1 3. 14.44-05

97.35.25-i

54.I7-3

14.49-1

54.27. 4-35

61.46. 16-4

28-2

—

i3. i8.35-8i

100. 3o. 27-7

—

—

53.20.48-15

61. 16.25-3

—

,,

, ,

—

—

Si. 7-48-15

59:25.35-5

—

I. i.56. 1-17

1 3. 1 5. 30-70

97.41.21-5

54. 17-1

14.49-0

47.47.59-70

56. 8. 4-8

II. i. 57. i -oo

1 3. 1 5. 32-47

97.41. 35-o

54. 17-1

14.49-0

47.48. 26-25

56. 8.34-3

29-7

December 26. Very cloudy.

172

TRANSIT OF VENUS, 1874. HONOLULU.

Day.

Observer.

Object.

Altazimuth-
Clock Time
of Vertical
Transit over
Mean of
Horizontal
Wires.

Lamp Right or Left. 1

Reading of
Vertical
Circle
corrected for
Runs of
Micrometers.

Level Indication (ad-
ditive).

Barometer and Ex-
ternal Thermometer.

Refraction.

True observed
Zenith
Distance.

1874.
December 3o

NI

Moon's L. L. ...

10. ii. 3i -70

n

o / //

2i5. 27. 55-o

n
67-4

3o'"- 10

78-9

0 / //

54. 32.43-9

, , ...

10. 20. 4-64

R

217. 9.29-3

67-1

63°' 6

74-2

52. 5i. 5-2

3i

NI

Moon's L. L. ...

9. 40. 3i-o8

B

197. 18. 59-4

62-2

63°- 1

178-6

72.43. 24-4

» » . . .

9.48.45-80

B

199. 1.17-3

62-9

161-8

71. 0.49-0

t > - • '

9.58.45 -32

E

2OI. 4.20-2

63-A

145-0

68.57.28-8

» > . . .

10. 8.44-36

£

336.52.27-i

77'4

62° -i

l3l'2

66. 55.28-3

, , ...

10. 17. 36-70

J,

335. 5.20-8

78-2

120-8

65. 8. 12-4

iSyS.
January i

NI

, , ...

10. 25.48-62
10. 38. 29-16

10.47. 22 '3O

10. 10. 24-52
10. 19. 35-5o
10. 3o. i8-5o

L

L
E

K
L
•L

332. 27. 3o'4

340. 20. i6-5
201. 28. 40-9

193. 42. 56-o
344. 18. 20-7
344. 18. 21-0

78-2

79'7
68-3

62-0
81-4
81-8.

61' -7

3o'"-o5
62° -6

60° • i
60° • o

107-7

i56-4
142-0

226-6
198-2
198-3

62. 3o. 8-9

70. 23.45-2
68. 33. 0-2

76. 20. 16-0
74.22. 32-9
74.22. 33-7

a? Librae

Moon's L. L. ...

» > • • »

10. 36.48-36

I.

343. i. 5-6

82-6

181-8

73. 5. 3-6

tt

10.43.48-84

I,

341. 38. 20-4

82-6

168-4

71.42. 4-0

, , ...

10. 52. 17-48

E

199. Sg. 18-4

65-6

60° -7

153-5

70. 2. 36- 9

, , ...

ii. o. 17-50

E

201. 3i. 53-9

65-i

29'° -97

141-7

68. 29. 5o-i

» y • • •

ii. 7.48-58

E

202. 57. 54-2

65-o

6i°-i

i3i-o

67. 3. 40-2

ii

T

Moon's L. L. . . .

2.55.16-46

!

E

208.26. 57-3

69-4

62° -o

io3-6

61.34. 3-3

December 3i. The adopted Zenith point corresponding to the mean wire is 270. o. 27-4
January i. „ „' „ 270.0.27-4
January 11. „ „ „ 270.0.26-4

TABLE IX. — LONGITUDE FROM THE MOON'S OBSERVED ZENITH DISTANCE (continued). 173

Greenwich Mean
Solar Time,
assuming the West
Longitude to be
I. ioh. 3i'".o«.
II. id1'. 3z'". oa.

Tabular Geocentric Elements
(K. A. and N. P. D. corrected).

Hour-Angle.

Tabular Zenith
Distance of
Star or
of Limb of
Moon.

Inferred
Longitude
West of
Greenwich
ioh. 3i"'. +

Apparent
Right
Ascension
of Center.

Apparent
North Polar
Distance
of Center.

Equatorial
Horizontal
Parallax.

Semi-
diameter.

h m »

0 t It

/ //

/ //

0 / //

o / //

I. 2. 3.55-yi i3.i5.44'73

97.43. 8-6

54. 17-0

14.49-0

45.52.32-55

54. 32. 3o'7

II. 2. 4. 55-54 i3. 15.46-50

97.43. 22-1

54. 17-0

14.49-0

45. 52. 59-10

54.33. o-i

26-9

I. 2.12.27-22 i3. iS.Sp-SS

97.45. 3-9

54. 16-9

14.49-0

43.48. 5-55

52. 5o. 49- 5

II. 2.13.27-06 I i3. 16. 1-62

97.45. 17-4

54. 16-9

14.49-0

43.48. 32-10

52. Si. 18-7

32-3

I. 1.29. 4-96 13.57.49-61

102. 5o. 8-4

54. IO'2

14.47-2

64. 8.44-40

72.43. 11-7

II. i. 3o. 4-80 i3.57.5i-43

102. 5o. 2O'9

54. IO'2

14.47-2

64. 9. 11-70

72. 43. 41 -o

26-0

I. I. 37. i8-33 i3. 58. 4-63

IO2. Si. 52' I

$4. 10- 1

14.47-2

62. 8.48-90

71. o. 34-3

II. 1.38.18-17 ! i3. 58. 6-45

102. 5z. 4- 7

54. 10- 1

14.47-2

62. 9. 16-20

71. I. 3-7

3o-o

I. I. 47. l6'22

1 3. 58.22-84

102. 53. 57-7

$4. lo- 1

14.47-2

59.43. 29-25

68. 57. i5-2

II. I.48.I6-05

13.58.24-66

102. 54. io-3

54. 10- 1

14.47-2

59.43.56-55

68. 57.44-6

27-8

I. 1.57. i3-63 13.58.41-04

102. 56. 3-2

54. 10- 1

14.47-1

57. 18. i6-5o

66. 55. 17-0

II. 1.58.13-46 i 13.58.42-86

102. 56. 15-7

54. lo- 1

14.47-1

57. 18.43-80

66.5S.46-3

23-1

I. 2. 6. 4-5i i3. 58. 57-22

102. 57. 54-6

54. 10- 1

14.47-1

55. 9. 14-10

65. 8. 3-4

II. 2. 7. 4-35 13.58.59-04

102. 58. 7-2

54. 10- 1

14.47-1

55. 9.41-40

65. 8.32-6

i8-5

I. 2.19.14-27 13.59.21-29

io3. o. S2-24

54. lo- 1

14.47-1

5i.57. i6-35

62. 3o. 53-4

II. 2. 10. 14-11 ! i3. Sg. 23- ii

io3. i. 4-79

54. 10- I

14.47-1

Si.57.43-65

62. 3i. 22-6

3i-8

14. 43. 56-72

io5. 3i. 15-7

—

—

61. lo. 59-70

70. 23. 47 -2

—

j j

1 1

—

—

58.57.41-60

68.33. 3-6

—

14.43. 56-75

io5. 3i. 15-9

—

68. ii. 58-o5

76. 20. I7-I

—

> t

,,

—

— '

65.54.13-35

74- "• 35'7

—

I. 2.14.49-09

14.44. 9-81

107.46. 9-8

54.13-2

14. 48-0

63. 16.44-25

74. 22. 2O '8

II. 2.15.48-93

14.44. 11-72

107. 46. 2I"O

54. i3-2

14. 48-0

63. 17. 12-90

74. 22. So'O

26-5

I. 2.21.17-89 14.44.22-26

107.47.22-4

54. i3-2

14. 48-0

61. 42. 23- 10

73. 4.48-5

II. 2.22.17-73

14.44.24-18

107.47. 33-6

S4- 1 3 • 2

14. 48-0

61. 42. Si'go

73. 5.17-7

3i-o

I. 2.28.17-22

14.44. 35-70

107. 48. 40-6

54. i3-3

14. 48-0

60. o. 37'5o

7I.4I.49-9

II. 2. 29. 17-06

14. 44. 37-62

107.48. Si- 8

54. i3-3

14. 48-0

60. i. 6-3o

71.42. 19-2

28-9

I. 2.36.41-47

14.44. 51-96

107. So. 1 5-2

54.13-3

14. 48-0

57.57.31-80

70. 2.25-3

II. 2. 37.44-30

14.44. 53-88

107. 5o. 26-4

54.13-3

14. 48-0

57-58. 0-60

70. 2.54-4

23-9

I. 2.44..43-I3

14.45. 7-32

107. 51.44-4

54. 13-4

14. 48-0

56. 1.21-90

68.29. 38-8

II. 2.45.43-OI

14.45. 9-23

107. 5i. 55-5

54.13-4

14. 48-0

56. i.5o-55

68. 3o. 7-6

23-5

I. 2. 52. I3'03

14.45.21-74

107.53. 8-1

54.i3-4

14. 48 - o

54. 12. IZ'OO

67. 3.26-8

II. 2.53.12-87

14.45. 23-66

107. 53. 19-3

54. 13-4

14. 48 - o

54. 12. 40-80

67. 3.55-9

27-6

I. 18. 1.49-42

23. 19. 17-34

97.27. 14-7

58. 19-6

i5. 55-2

54. 12. 36 -60

61. 34. 19- 7

II. 18. 2.49-25

23. 19. 19-39 97. 26. 59-0

58. 19-6

i5. 55-2

54.12. 5-85

61. 33.45-4

28-7

z 2

174

TRANSIT OF VENUS, 1874. HONOLULU.

Day.

1

0

Object.

Altazimuth-
Clock Time
of Vertical
Transit over j S
Mean of
Horizontal
Wires.

i

Reading of ^
Vertical ! .2
Circle
corrected for '-3 •
Runs of 5 ^
Micrometers. -3 »3

Barometer and Ex-
ternal Thermometer.

Refraction.

True observed
Zenith

Distance.

1875.
January i i

T

Moon's L. L. ...

h m 8

3. 9. i3-6o

•

p / //
205.32. iS-5

69-9

3o'""oo

H7-3

0 / //

64.28. 58-3

,,

3. 1 6. i8-5o

R

204. 2. 52'4

69-9

125-5

65. 58.29-6

,,

3. 22.41-08

L

337. -6.36-8

69-4

133-9

67. 19. 33-7

„

3.28.5i-5o

L

338.35. 17-4

70-2

i43-3

68. 38.24-5

,,

3.36.25-68

S,

340. 12. 9'I

70-4

6i°-o

i56-o

70. i5. 29- 1

i3

n

Moon's L. L. ...

3.58. i-5o

K

222.58.55-2

69-0

6l°'2

60-4

47. 1.22-6

,,

4. 6.56-28

R

221. I. 9-4

68-9

64-7

48. 59. rz -8

,,

4. i5. 34-10

K

219. 6.40-4

69-2

69-3

So. 53.46-1

,,

4.23. 6-08

^

322.32. 1-8

70-6

73-7

52. 33. 59-7

4. 3o. 37-86

L

324. 12. 29- 5

71-2

78-1

54. 14. 32-4

NI

0 Arietis

4-38.36-3o

4.48. 19-92
4. 56.40-58

4. 34. 22*14

L

L

•

R

325.59- 5-3
3i2. i5. 54-5

225. 46. 57- I

229. 2. 40 • 4

7i-3

70-8 .
72-7

71-1

29'° -97
59° '9

83-5

5i-4
54-9

48-4

56. i. 13-7

42. 17. 3o-3
44. 1 3. 1 1 • 5

40.57.23-3

Moon's L. L. ...

,,

4. 41. 10-42

K

227. 3o. 52-3

70-5

5i-,

42.29. 14-7

,,

4.47. 31-76

R

226. 5. 5-6

70-0

65°- 2

53-7

43.55. 4-5

,,

5. 12. 50-44

L

3i9.35.37-5

73-4

65-5

49. 37. 3o-o

,,

5. 20. 20-42

L

321.17. 3-6

73-o

29'" -94

69-4

Si. 18.59-6

"

5.27. 5-72

I

322.48. 26-9

73-4

67° -8

73'2

52. 5o. 27- 1

O / //

January 11 to January 14. The adopted Zenith point corresponding to the mean wire is 270. o. 26-4

TABLE IX. — LONGITUDE FROM THE MOON'S OBSERVED ZENITH DISTANCE (continued). 175

Greenwich Mean
Solar Time,
assuming the West
Longitude to be
I. ioh. 3i°'. os.
II. ioh. 32m. o".

Tabular Geocentric Elements
(R. A. and N. P. D. corrected).

Hour-Angle.

Tabular Zenith
Distance of
Star or
of Limb of
Moon.

Inferred
Longitude
West of
Greenwich
iob. 3im. +

Apparent Apparent
Eight North Tolar
Ascension Distance
of Center. of Center.

I

Equatorial • Q

HS? •£=*

h ni s

O / //

/ //

/ //

0 / //

0 / //

I. 18. 15.44-27

23. 19. 45-93

97.23.35-6

58. 19-8

i5. 55-3

57. 34. 45-00

64. 29. 12-2

II. 18. 16.44- ii

23. 19.47-98

97.23. 19-9

58. 19-8

iS.55-3

57. 34. 14-25

64.28. 37-9

24-3

I. 18.22.48-02

23.20. 0-43

97.21.44-3

58. 19-9

15.55-3

59. 17. 21 -OO

65. 58.46-5

II. 18.23.47-85

23. 20. 2 'So

97.21. 28-6

58. 19-9

iS.55-3

59. 16.49-95

65.58. 11-9

29-5

I. 18.28.59-58

23. 20. i3-5o

97.20. 4-1

58. 2o'o

i5. 55-4

60.49.43-65

67. 19. So- 5

II. 18. 29. 59-42

23.20. 15-55

97.19.48-4

58.20-0

'5.55-4

60.49. I2 '9°

67. 19. 16-2

29-4

I. 18.35.18-97

23. 20. 26-I3

97. 18.27-1

58. 20-1

i5. 55-4

62. 19. io'65

68. 38.41-4

II. 18.36. 18-81

23.20.28-18

97. 18. 11-4

58. 20-1

i5. 55-4

62. 18. 39-90

68.38. 7-2

29-6

I. 1 8. 42. Si-gi

23. 20. 41-65

97. 16.28-0

58. 20-2

15.55-4

64. 8.5o-55

70.15.47-5

II. i8.43.5i-75

23. 20.43-69

97. 16. 12-3

58.20-2

1 5. 55-4

64. 8. 19-95

70. i5. i3-3

32-3

I. 18.56.33-34

o. 59. 34-84

84. ii. 29-8

58.58-7

16. 5-9

44.49.44-55

47. 1.41-1

II. 18.57.33-18

o. 59. 36-92

84. ii. i3-6

58.58-7

16. S-g

44.49.I3-35

47. i. 6-1

3i-7

I. 19. 5. 26-64

0.59.53-34

84. 9. 5-3

58.58-8

16. 5-9

46. 58.48-45

48. Sg. 3i-2

II. 19. 6.26-48

o. 59. 55-42

84. 8. 49 • i

58. 58-8

16. 5'9

46. 58. 17-25

48. 58. 56-2

3i-8

I. 19. 14. 3-04

I. O. II "26

84. 6.45-4

58.58-9

16. 6-0

49. 3.46-80

So.54- 4-9

II. 19.15. 2-88

I. 0.13-34

84. 6. 29 • i

58.58-9

16. 6-0

49. 3. i5-6o

5o.53. 3o-o

32-3

I. 19. 21. 33-77

I. 0.26-91

84. 4.43-2

58.59-0

16. 6-0

5o. 52. 5i-6o

52.34.23-7

II. I9.22.33-6I

1. 0.28-98

84. 4, 27 • o

58.59-0

16. 6-0

5o.52.2o-55

52.33.48-9

41-4

I. 19.29. 4"3i

I. 0.42-55

84. 2. 41 • 2

58.59-1

16. 6-0

52.4I.53-55

54. 14. 55-o

II. 19. 3o. 4- 1 5

I. 0.44-62

84. 2.25-0

58.59-1

16. 6-0

52. 41. 22' So

54. 14. 20-3

39-i

I. 19. 37. 1-43

I. 0.59-10

84. o. 32 -o

58.59-1

16. 6'o

54.37.2I-75

56. 1.36-5

II. 19.38. 1-27

i. i. 1-18

84. o. i5-8

58.59-1

16. 6-0

54.36.50-55

56. i. 1-6

39-2

1.47.43-90

69.48. 7-8

—

—

45.22. 3-90

42. 17. 3o-5

—

) J

» »

—

—

47. 27. i3-65

44. i3. ii- 1

—

I. 19. 28. 52-71

i. Si. 42-14

77.42.51-8

•59. i3-2

16. 9-8

40. 53. i3-5o

40.57.43-9

II. 19. 29. 52-54

I. 51.44-32

77.42. 36-6

59. i3-2

16. 9-8

40. 52. 40-80

40.57. 8-8

35-2

I. 19.35.39-88

i. Si. 56-91

77.41- 8-3

59.13-3

16. 9-8

42. 3i. 36- 3o

42.29. 33-2

II. 19.36.39-72

i. Si. 59-07

77.40. 53-i

59. i3-3

16. 9-8

42. 3i. 3-90

42.28. 58-3

3l-8

I. 19.42. 0*19

i. 52. 10-69

77.39.31-6

59-13-3

16. 9-8

44. 3.29-85

43.55.24-6

II. 19.43. O'O2

i. 52. 12-86

77.39.16-4

59-13-3

16. 9-8

44. 2.57-30

43.34.49-7

34-6

I. 20. 7. I4-73

1.53. 5-66

77.33. 7-1

59. i3-5

16. 9-9

So. 9.25-65

49.37.49-6

II. 20. 8.I4-57

1.53. 7-83

77. 32. 51-9

59.I3-5

16. 9-9

So. 8.53-10

49. 37. 14-7

33-7

I. 2O. 14. 43-49

i. 53. 21-96

77. 3i.i3-3

59. i3-6

16. 9-9

Si. 57. 5i-oo

5i. 19. 20-7

II. 20.15-43-33

i.53.24-i3

77. 3o. 58-i

59. i3-6

16. 9-9

5i.57.i8-45

5i. 18.46-0

36-5

I. 20.2I.27-72

i. 53.36-64

77. 29. 3o-8

59.I3-6

16. 9-9

53. 35. 3o-45

52. So. 46- 7

II. 20.22.27-55

1.53.38-82

77.29. i5-6

59. i3-6

16. 9-9

53. 34. 57-75

52. So. ii -6

33-5

January ii. Moon unsteady. Aperture reduced.

176

TRANSIT OF VENUS, 1874. HONOLULU.

Day.

Observer.

Object.

Altazimuth-
Clock Time
of Vortical
Transit over
Mean of
Horizontal
Wires.

o>

1-5
h

o

2
.SP

Or

a
^

i

Reading of ^
Vertical .2
Circle |
corrected for '-3 ^
Runs of S t
Micrometers. ^5 "-S

|«

1-5

Barometer and Ex-
ternal Thermometer.

Refraction.

True observed
Zenith
Distance.

iSyS.
January 14

81

h in s

5.40. 56' 04
5. 5i. 17-96

L

K

o / //
324. 22. 21-8

2i3. i3. 48-3

rf
74-0
70-6

65°'9

77-6
84-9

54. 24. 27-0
56. 46. 52-4

i5

T

Moon's L. L. ...

4.42.43-34

L

298.38. 4'0

78-2

64° -o

3o-6

28. 39. 26-4

> > ...

4. 5o. 56 -16

L

3oo. 29. 43-6

78-4

29'"' -85

33-o

3o. 3i. 8-6

, , ...

4. 58. 29-96

L

302. 12. 30'0

78-7

35-3

32. 1 3. 57-6

> > • • •

6. 0.58-88

IJ

223. 39. 3o-o

63-8

58-6

46. 20. 5 1 -2

, , ...

6. 7. 19-06

11

222. 14. 4-6

63-6

6i-5

47.46. 19-7

, , ...

6. 19. i8-36

R

2ig. 32.45-5

62-6

-

67-6

5o. 27. 45-9

16

XI

Moon's L. L. ...

6. 16. 44-68

K

234. 1 6. 26-2

63-4

7i°'5

39-7

35.43. 36-5

,, ...

6. 26. 40-86

li

2'32. 3. 5i'7

63-o

43-o

37.56.14-7

, , ...

6. 45. 54- 14

It

227.48. 2-3

63-2

5o-o

42. 12. IO'9

9 ) ...

6.55.20-28

&

314. i5. 39-3

79-0

72° -I

53-8

44. 17. 25-7

, , ...

7. 3.3o-66

L

3i6. 3.48-1

79'4

57'2

46. 5.38-3

17

M

? , ...

AJdebaran

7. ii. 34-62

7- 20. 35-l6
7.2S. I8-24

5. 27. 42-96

L

L
R

K

317. 5o. 26-9

3n. 2.28-2
227. 8. i3-o

258. 29.47-2

80-2

81-2
62*0

66-6

72° -7

29"' -91
73°-i

68°-o

60-9

48-0
5i-i

11-4

47. 52. 21 -6

41. 4. II -o
42. 52. 2-5

II. 29. 43-5

Moon's L. L. ...

, , ...

5.38. 11-98

K

256. 22. 3i -4

65-4

i3-5

13.37. 2-6

, , ...

5.45. 21-72

It

254. 53. 32-9

65-o

i5-i

1 5. 6. 3-i

j » ...

5. 55. 19-40

L

287. 10. 36- 5

75-5

17-3

17. 11.43-4

O / //

January i5 and 16. The adopted Zenith point corresponding to the mean wire is 270. o. 26*4
January 17. » » » 27°- °- 25'9

TABLE IX. — LONGITUDE FROM THE MOON'S OBSERVED ZENITH DISTANCE (continued). 177

Greenwich Mean
Solar Time,
assuming the West
Longitude to he
I. ioh. 3i™. o".

II. I0h. 32'". 0".

Tabular Geocentric Elements
(H. A. and N. P. D. corrected).

Hour-Angle.

Tabular Zenith
Distance of
Star or
of Limb of
MOOD.

Inferred
Longitude
West of
Greenwich
I0h. 3im. +

Apparent Apparent
Right North Polar
Ascension Distance
of Center. of Center.

1

Equatorial
Horizontal
Parallax.

Semi-
diameter.

h m s

h in s

O 1 II

I
' " ' "

0 , /,

0 , „

i

I.47.43-88

69.48. 7-9

—

—

58. 3i. 16-80

54. 24. 28-9

—

» »

i »

—

—

61. 6.45-75

56. 46. 55-2

—

I. 19. 33. 16-89

2. 45. 38-74

71. 56.41-3

59.23-1

16. 12-6

29. 29. 26-55

28. 39.41-4

II. 19. 34. 16-72

2.45.41-05

71. 56. 28-0

59.23-1

16. 12-6

29. 28. Si-go

28.39. *' 5

25-8

I. 19.41.28-37

2. 45. 57-69

71. 54. 52-i

59.23-1

1 6. 12-6

3i. 27. 54-60

3o. 3i. 21-9

II. 19. 42. 28-20

2. 45. 59-99

71. 54. 38-8

59. 23-1

16. 12-6

3i. 27. 20-10

3o. 30.47-1

22-9

I. 19.49. 0-93

2.46. 15-14

71. 53. n-6

59.23-2

16. 12-6

33. 16.59-85

32. 14. 10-8

II. 19. So. 0-76

2.46. 17-45

71. 52. 58-4

59.23-2 : 16.12-6

33. 16.25-20

32.i3. 35-9

22-7

I. 20. Si. 19-61

2.48. 39-52

71. 39. 25-4

59. 23-5

1 6. 12-7

48.18. 7-95

46. 21. 4'3

II. 20. 52. 19-44

2. 48. 41 ' 84

71. 30. 12-2

59.23-5

1 6. 12-7

48. 17. 33-i5

46. 20. 29- 5

22-5

I. 20.57.38-74

2. 48. 54' 19

71.38. 2-0

59.23-5

1 6. 12-7

49. 49. 3o-6o

47.46. 32-8

II. 20.58.38-58

2.48. 56- 5i

71. 37.48-8

59-23-5

1 6. 12" 7

49.48. 55-8o

47.45.57-5

22-3

I. 21. 9. 36-O7

2. 49. 21 -95

7I.35.24-3

59.23-5

16. 12-7

52.42. 23-70

So. 27. 59- 1

II. 21. IO. 35-9I

2.49.24-27

71. 35. n-2

59.23-5

1 6. 12-7

52.41.48-90

5o. 27. 24- 1

22-6

I. 21. 3. 7'52

3.46.43-99

66.54. 3'9

59.27-4

16. 13-7

37.43. 36-go

35.43.49-5

II. 21. 4. 7-35

3. 4.6. 46- 46

66.53.53-7

59.27-4

16. 13-7

37.42. 59-85

35.43. 14-9

22-5

I. 21. i3. 2-07

3.47. 8-57

66. 52.22-8

59.27-3

16. i3-7

40. 6. 3i-o5

37. 56. 29-0

11. 21. 14. 1-90

3. 47. 11-04

66. 52. 12-7

59.27-3

16. i3'7

40. 5. 54-00

37.55.54-2

24' 7

I. 21.32.12-23

3.47. 56-14

66.49. 8"i

59.27-3

1 6. 13-7

44. 42. 57-00

42.12.24-9

11. 21.33.12-06

3.47. 58-62

66.48. 58-o

59.27-3

16. 13-7

44. 42. 19-80

42. 11.49-8

23-9

I. 7.I-4I.36-82

3.48. 19-52

66.47. 32-8

59.27-3

16. 13-7

46. 58. 38-40

44- i7-4''°

II. 21.42.36-65

3. 48. 22-00

66. 47. 22-7

59.27-3

16. 13-7

46. 58. 1-20

44. 17. 6-0

26-2

I. 21.49.45-87

3.48.39-77

66. 46. 10-4

59.27-3

1 6. 13-7

48. 56. io- So

46. 5. Sg-o

II. 21. 50.45-70

. 3.48.42-24

66.46. o-3

59.27-3

1 6. 13-7

48. 55.33-45

46. 5.23-9

35-4

I. 21.57.48-52

. 3.48.59-76

66. 44. 49- 3

59.27-3

16. 13-7

5o. 52. 10-20

47. 52.40- 1

11. 21.53.48-35

3.49. 2-24
4. 28. 45-61

66. 44. 39-2
73.44. 3o-3

59.27-3

16. 13-7

So. Si. 33-oo
43. io. So- 70

47- 52. 4-9
41. 4. 9-0

3i-5

> »

•> i

—

—

45. 6. 36-90

42. Si. 59-9

—

I. 20.10.18-58

4. 45. 40-96

63. 39. 56-S

59.24-0

16. 12-8

10.44. 6-60

n. 29. 54-8

II. 20. ii. 18-41

4.45.43-57

63. 39. 50-4

59.24-0

16. 12-8

io. 43. 27-45

n. 29. 24-8

22-6

I. 20.20.45-89

4. 46. 8 • 29

63.38.49-6

59.23-9

1 6. 12-7

i3. 14. 3i-io

i3. 37.11-8

II. 20.21.45-73

4. 46. 10-89

63. 38. 43-2

59.23-9

1 6. 12-7

i3. i3. 53-ic

i3. 36.40-8

17-8

I. 20. 27. 54-56

4. 46. 26-95

63.38. 3-8

59.23-9

16. 12-7

14. 57. 18- 3o

i5. 6. iS-i

11. 2O. 28. 54-29

4.46. 29-56

63. 37. 57-4

59.23-9

16. 12-7

14. 56. 39-15

IS. 5.43-7

22-9

I. 20.37.50-52

4.46. 52-91

63.37. o-3

59.23-8

1 6. 12-7

17. 20. 14-25

17. ii. 56-9

11. 2o.38.5o-35

4.46. 55-52

63. 36. 54-o

59.23-8

16. 12-7

17. 19. 35- io

17. ii. 24-3

24-9

January i5. Aperture reduced. Fine limb.

178

TRANSIT OF VENUS, 1874. HONOLULU.

Day.

Observer.

Object.

Altazimuth-
Clock Time
of Vertical
Transit over
Mean of
Horizontal
Wires.

eg

3

s

60

m

M

§
>3

i

Reading of
Circle .2
corrected for g
Vertical H3 .
Runs of j >3 ^
Micrometers. "3 "3

r

Barometer and Ex-
ternal Thermometer.

Refraction.

True observed
Zenith
Distance.

1875.
January i 7

HI

h m s

6. S.SS-go

L
L

288. 56.43-3
290. 34. 3i-o

//

77-1

77-5

3o'"-oi
67° -o

n
19-2

21 -Q

0 / //

18.57.53-7

20. 35.43-6

, , ...

6. n. 16-20

iS

NI

Moon's U. L. ...

3. 22. 31-44

L

3o2. 40. 34-9

65-6

67° -2

35-9

32.41. 5o-5

,,

3. 3o. i • 52

L

3oi. 4. 3o-3

66-7

33-8

3i. 5.44-9

1 ) * • •

3. 37. 12-64

L

299.32. 39-7

66-7

3i-8

29. 33. 52-3

J > • • *

3.44. 31-70

K

241. 5g. Jo-5

77-2

29-9

28. 0.28-1

> ? ...

3. 51.49-26

R

243.32. o-5

76-0

3oin-u

26-7

26.27. 36-i

> ) ...

3.58.25-3o

K

244. 55.46-9

74-6

64° -8

•26-3

25. 3. 5o-7

'

7 Geminorum . . .

4. 8.54-80

R

z36. 26. 56-i

72-1

37-3

33.32.55-o

> >

4. 19. 1-48

L

3oi. 10. 25-9

67-4

64° -o

34- 1

3i. 11.41-5

19

HI

Moon's U. L. . .

3.38.54-24

L

3i3.28. 54-3

62-6

69° -3

53-i

43. 30.24-1

» »

3.45.45-08

L

3i2. i. 5-6

63-2

5o-5

42. 2.33-4

, , ...

3. 53. 56-48

L

3io. 16. i -4

63-6

47-5

40. 17. 26-6

, , ...

4. 1.43-76

U

23 I. 22. 21 "I

81-8

44-8

38. 37.27-8

» » ...

4. 8.30-64

K

232. 49. 26-9

81-0

42-6

37. 10. 20-6

I

» » • * •
Pollux

4. 16.42-72

4. 26. 26-64
4. 36.47-02

10.52. 3'20

K

K
L
R

204. 34.44-4

226. 3i. 9-4
3n. 10. 56-i
217. 38.49-9

79'7

79'4
62-2
67-6

66° -9

3oin'20

66° -8

62° -5

40-0

53-3
49-2
73-3

35.25. 1-8
43. 28. 50-4

41. 12. 21-6
52. 21. 41-7

Moon's L. L. ...

, , ...

10. 5g. 27-66

K

216. 4. i5'o

67-0

77-5

53. 56.21-4

o / //

January 18. The adopted Zenith point corresponding to the mean wire is 270. o. z5-9
January 19. „ „ „ 270.0.25-9

TABLE IX. — LONGITUDE FROM THE MOON'S OBSERVED ZENITH DISTANCE (continued). 179

Greenwich Mean
Solar Time,
assuming the West
Longitude to be
I. ioh. 3im. o".

II. I0h. IV". O5.

Tabular Geocentric Elements
(R. A. and N. P. D. corrected).

Hour-Angle.

Tabular Zenith
Distance of
Star or
of Limb of
Moon.

Inferred
Longitude
West of
Greenwich
ioh. 3im. +

Apparent
Right
Ascension
of Center.

Apparent
North Polar
Distance
of Center.

Equatorial
Horizontal
Parallax.

Semi-
diameter.

h m *

0 / //

/ //

f ff O / //

O t It

I. 20.46. 8-66

4.47. 14-62

63.36. 7-6

59.23-8

1 6. 12-7

19. 19. 41*10

18.58. 7-3

II. 20.47. 8-49

4.47. 17-23

63.36. i-3

59.23-8

16. 12-7

19. 19. 1-95

18. 57. 34-4

24-8

I. 20. S3.44'7I

4.47. 34 -5o

63.35.i9-5

59.23-8

16. 12-7

21. 9. 2-40

20.35. 57-8.

II. 20. 54. 44' 54

4.47. 3y- 1 1

63. 35. i3-2

59.23-8

1 6. 12-7

21. 8.23-25

20. 35. 24-3

25-4

I. 18. 1.32-29

5.43.37-34

62. 3.17-7

59.i3-7

16. io'o

35. 2.42-30

32.41. 34-3

II. 18. 2.32-13

5. 43. 40-01

62. 3. i5-4

59-13-7

16. io'o

35. 3.22-35

32.42. 9-6

27-5

I. 18. 9. i-i3

5.43.57-37

62. 3. 0-4

59. i3-6

16. io'o

33. i5. n-85

3i. 5. 3o-i

II. 18. 10. 0-96

5.44. 0-04

62. 2.58-1

59. i3-6

16. jo-o

33.i5.5i'9o

3i. 6. 5-6

25-o

I. 18. 16. 11-06

5.44. 16-55

62. 2. 43 • 9

59. i3-6

16. 9-9

3i.32. i3-o5

2g.33.36-8

II. 18.17.10-89

5. 44. 19-22

62. 2.41-7

59. i3-6

16. 9-9

3i.32.53-io

29. 34. 12-5

26-1

I. 18.23.28-89

5. 44. 36-09

62. 2.27-3

59.I3-5

16. 9-9

29. 47. 20- 55

28. o. 12-9

II. 18.24.28-73

5-44-38-77

62. 2.25-1

59-13-5

16. 9-9

29.48. 0-75

28. 0.48-5

25-6

I. i8.3o.45-25

5-44-55-57

62. 2. 1 1 ' O

59.13-4

16. 9-9

28. 2.49-50

26. 27. 22'3

II. 18.31.45-09

5.44. 58-25

62. 2. 8-8

59. i3-4

16. 9-9

28. 3.29-70

26.27. 57-7

23-4

I. 18.37.20-19

5-45. i3'i8

62. i. 56-4

59. i3-3

16. 9-9

26.28.I3-35

25. 3.34-9

II. 1 8. 38. 20-02

5.45. i5-87

62. i. 54- 1

59.I3-3

16. 9-9

26.28. 53-70

25. 4. 10-7

26-5

6. 3o. 3o-54

73.29.39-3

—

—

35.10. ii -55

33. 32. 50-9

—

* »

» »

—

—

32.38. 3i-8o

3i. 11.41-8

—

I. 18.13.57-19

6. 48. 19-89

62. 4. 8-5

58.53-6

16. 4-5

47. 7.28-20

43. 3o. 8-3

II. 18.14.57-03

6.48.22-53

62. 4. 10-9

58.53-6

16. 4-5

47. 8. 7-80

43. 3o.43-3

27-1

I. 1 8. 20. 46-91

6.48.37-99

62. 4. 24-8

58.53-5

16. 4-5

45.29.17-25

42. 2. 19*6

II. 18.21.46-74

6. 48. 40* 63

62. 4. 27-2

58.53-5

16. 4-5

45.29. 56-85

42. 2. 54*8

23-5

I. i8.28.56-95

6.48.59-63

62. 4. 44- 5

58. 53-4

16. 4-4

43. 3i. 5i-oo

40. 17. i3'7

II. 18.29.56-79

6.49. 2-25

62. 4.47-0

58.53-4

16. 4-4

43. 32. 3o-3o

40. 17.48-4

22-3

I. 1 8. 36.42-94

6. 49. 20-20

62. 5. 3-5

58.53-2

16. 4-4

41. 40. io-5o

38. 37. i3-7

II. 18.37.42-78

6. 49. 22-85

62. 5. 5-9

58.53-2

16. 4-4

41.40. 5o-25

38.37.48-8

24-1

I. 18.43.28-71

6.49. 38-n

62. 5. 20' I

58.53-1

16. 4-4

40. 2. 56- 10

37.10. 7-7

II. 18.44.28-54

6.49.40-75

62. 5.22-6

58.53-1

16. 4-4

40. 3. 35-70

37. 10.42-7

22-1

I. i8.5i.39-43

6.49. 59-78

62. 5.40-4

58.53-0

16. 4-3

38. 5.20-25

35.24.47-6

•

II. 18.52.39-26

6. 5o. 2-42

62. 5.42-9

58.53-0

16. 4-3

38. 5.59-85

35.25.22-5

24-4

7. 37.41-34

61. 40. 21 -o

,-; _

—

47.34.45-00

43.28.54-5

—

,,

,,

—

—

44. 59. 39-60

41. 12. 25-6

—

I. I.25.55-45

7- 7- '8-98

62.26. 6-5

58. 45-9

16. 2-4

56.25. 3-75

52.21. 54-I

II. 1.26.55-29

7- 7- 21-59

62. 26. io-3

58. 45-9

1 6. 2-4

56. 24. 24- 60

52. 21. 19-9

21-8

1. 1.33.18-69

7. 7-38-34

62. 26. 34-1

58. 45-8

16. 2-3

58. n.20-25

53. 56. 3i-6

II. 1.34. i8-53

7- 7-4°'96

62.26. 37-8

58. 45-8

16. 2-3

58. 10. 40-95

53.55.57-4

17-9

January 18. Aperture reduced. January 19. Aperture reduced. Pollux unsteady.

A A

180

TRANSIT OF VENUS, 1874. HONOLULU.

Day.

Observer.

Altazimut!]-
Clock Time
of Vertical
Object. Transit over
Mean of
Horizontal
Wires.

4 Heading of
g Vertical
»j Circle
.tc ; corrected for
5 Kuns of
2- Micrometers.
5
H

Level Indication (ad-
ditive).

Barometer and Ex-
ternal Thermometer.

Refraction.

True observed
Zenith
Distance.

i875.
January 19

T

Moon's L. L. ...

Ii m s
II. 4.40-08

K

0 / H

214. 57. 53-5

//
^66-8

3o'"-i9

n
80-6

55. 1.46-2

» > - - -

II. 9.40-16

R

2 1 3. 54. 13-7

66-2

64° -O

83-8

56. 6.29-8

, , ...

ii. 17. 38- 14

I,

327.45. 28-2,

76-9

89-3

57.47.48-5

,,

ii. 23. 47-34

I.

329. 3.32-9

77-6

93-9

59. 5.58-5

•> J ' ' •

11.28. 59-28

L

33o. 9.20-8

78-4

98-1

60. ii. 5i -4

20

T

> » ' • •

Pollux

n. 34. 14-80

11.40. 19-28
11.47.41-92
ii. 55. 17-96

12. 1.44-36

4. 32. 53-34

4. 37. 58-40
4.44. 12-44

4. Si. 19^34

4.57. 17-78

L

L
I.
R
R

E
K
I,
L
L

33i. 15.48-9

325. 7. 16-0
326.43. 39-3
2ii.35.33-2

2IO. II.43-2

227. 56. 22-8
229. 3.29-8
309. 32.43-2
307. 58. 5o-4
3io. 37.46-8

79-0

79-1

79'4
66-4

65-7

76-6
76-4
63-6
64-0
64-6

7i°-o
3o""24

1 02 -6

80-8

85-8
91-4
96-5

5o-5
48-5
46-2

43-7
48-0

61. 18. 24-6

55. 9. 3o-o
56.45. 58-6
58.25. 17-7
59.49. i3-5

42. 3.37-0
40. 56. 28-2
39.34. 7-1
38. o. 12-2
40. 39. 1 3- 5

Pollux

Moon's U. L. ...

, L. L. ...

4.59. 52-72

L

*3io. 36. 15-7

64-6

48-0

40.37.42-4

,, U.L. ...

5. 7.58-38

I

3o8. 1 8. io-5

65-2

44-2

38. 19. 34-0

,, U.L. ...

5. 14. 21 -5o

L

306.54. 38-8

65-o

42-0

36.55.59-9

,, L.L. ...
U. L. .

5. 16. 49- 52
5.22.57-54
5. 3o. 23-i6

1.
R
R

306.54. 38-8
234. 56. 32-2
236.33.52-o

65-o

77-0
76-2

42-0

39-2

36 -9

36. 55.59-9
35. 3. 15-9
33.25.54-6

, , U. L. . . .

,, U.I

5. 39. 32-90

R

238.34- «'»

?5'4

34'2

1

3i.25.43-5

0 / //

January 20. The adopted Zenith point corresponding to the mean wire is 270. o. 25 • 9

* The first wire was lost : the circle-reading has been diminished i'. 3i"- 1.

TABLE IX. — LONGITUDE FROM THE MOON'S OBSERVED ZENITH DISTANCE (continued). 181

Greenwich Mean
Solar Time,

Tabular Geocentric Elements
(R. A. and N. P. D. corrected).

Tabular Zenith i Inferred
Distance of j Longitude

assuming the West
Longitude to be

Apparent
Right

»tffip£ r ! a^

Semi-

Hour-Angle.

Star or West of
of Limb of Greenwich

I. io''. 3 1"1. o~.

II. IO1'. 32'". 0\

Ascension
of Center.

Distance „ ,.
of Cent-r.

diameter.

Moon.

io1'. 3 1"'. +

h in M

0 / // / //

o / //

I. i.38.3o-26

7. 7.51-96

62.26.53-6 58.45'7

16. 2-3

59.26. 2'25

55. 2.57-6

II. i. 3g. 3o-io

7. 7-54-57

62.26.57-3 58.45'7

16. 2-3

59. 25. 23-10

55. 2.23-0

19-8

I. 1.43.29-52

7. 8. 5-o3

62. 27. 12-3 58.45-6

16. 2-3

60. 37. 47-40

56. 6.40-2

II. i. 44. 29- 36

7- 8. 7-64

62.27.16-1 58.45-6

16. 2-3

60.37. 8-25

56. 6. 6-3

18-4

r. i. 5i. 26-20

7. 8.25-85

62.27.42-5 58.45-4

l6. 2'2

62. 32. 4-80

57.47.59-9

II. i. 52. 26-04

7. 8.28-46

62. 27.46-3

58. 45-4

16. 2-2

62. 3i.25-65

57.47.26-1

2O- 2

I. i. 57. 34-40

7. 8.41-92

62.28. 5-8

58. 45-3

1 6. 2'2

64. O. 21 -90

59. 6. 7-5

II. 1.58.34-24

7. 8. 44- 54

62.28. 9-6

58. 45-3

l6. 2-2

63. 59. 42-60

Sg. 5.33-6

i5-9

*

I. 2. 2.45-49

7. 8.55-Si

62. 28. 25-7

58. 45-2

l6. 2'2

65. 14. 57'i5

60. 12. i-3

II. 2. 3.45-33

7. 8.58-12

62. 28. 29-5

58.45-2

l6. 2' 2

65. 14. 18-00

60. n. 27-7

17-7

I. 2. 8. o-:5

7- 9- 9'24

62. 28.45-8

58. 45 -i

16. 2-1

66. 3o. 24-00

61. 18. 34-2

II. 2. 8.59-98

7. 9.11-85

62. 28.49-6

58.45-i

16. 2-1

66. 29. 44- 85

61. 18. 0-7

17-2

7.37.4I-33

6 1 . 40. 20 • 8 i

—

60. 53.29-85

55. 9.27-5

—

,,

—

—

62.44. 9 '4-5

56.45.59-3

—

,,

,,

—

—

64. 38. io'o5

58.25. i5-6

—

'''

"

—

66.14.46-05 ! 59.49.13-1

—

7.37.4i-35

61. 40. 21 -o j

45. 57. 49-20

42. 3.36-7

—

'

,,

,,

—

—

44.41. 33-i5

40. 56. 29-0

—

» *

,,

—

—

43. 8. 2-55

39. 34. io-5

—

, ,

—

—

41. 21. 18-90

38. o. 14-0

—

I. 19. 28. 12-96

7. 53.44-25

64. 1.47-8

58.23-4

15.56-2

43. 52. aS-Xo

40. 39. i-5

II. 19. 29. 12-80

7. 53.46-76

64. I. 54-6

58.23-4

i5. 56-2

43.53. 3-45

40. 39. 35-8

21-0

I. 19.30.47-49

7.53. 5o-73

64. 2. 5*4

58.23-3

i5. 56-2

43. i5. 18-75

40.37.33-6

II. 19.31.47-33

7.53.53-24

64. 2. 12 "2

58.23-3

i5. 56-2

43. 1 5. 56-40

40. 38. 7-6

i5-3

I. 19.38.51-82

7. 54. n-o5

64. 3. 0-6

58.23-1

i5. 56-i

41. 18.58-65

38. 19. 24-0

II. 19.39.51-66

7.54.13-57

64. 3. 7-4

58.23-1

i5.56-i

41. 19. 36-45

38. 19. 58-3

17-8

I. 19. 45. 13-90

7. 54. 27-08

64. 3. 44- 2

58.23-0

I5.56-I

39.47. 12- 15

36.55.48-0

II. 19.46. 13-74

7.54.29-59

64. 3. 5i-o

58.23-0

I5.56-I

39.47.49-80

36.56. 22-1

20-9

I. 19.47.41-52

7.54.33-27

64. 4. i • i

58.22-9

I5.56-I

39. 11.44-70

36.55.47-7

II. 19.48.41-35

7. 54.35-78

64. 4. 7-9

58.22-9

i5. 56-i

39. 12. 22-35

36. 56. 21-6

21-6

I. 19. 53. 48- 54

7. 54.48-66

64. 4. 43 - 1

58.22-8

I5.56-I

37.43.35-10

35. 3. 6-5

II. 19.54.48-38

7. 54. 5i-i7

64. 4. 5o-o

58.22-8

i5. 56-i

37.44. "'75

35. 3.40-5

16-5

I. 20. i. 12-94

7-55. 7-29

64. 5. 34- 1

58.22-6

i5. 56-o

35.56.5o-25

33.25.43-8

II. 20. 2. 12-78

7-55. 9-80

64. 5.41-1

58.22-6

i5. 56-o

35. 57. 27-90

33.26.17-7

19-1

I. 2O. IO. 21 -2O

7. 55. 3o-26 64. 6. 37-4

58.22-4

i5.56-o

33.45. 8-55

3i.25. 32-4

II. 20. ii. 21 -o3

7. 55. 32-76 64. 6. 44-3

58. 22-4

i5. 56-o

33.45.46-05

31.26. 5-8

19-9

January 20. Aperture reduced. Pollux unsteady. Moon in cloud. Full moon occurred at i5''. 12"'- i. Honolulu

Sidereal Time. The observations of )) L. L. by T have not been used.

A A 2

182

TRANSIT OF VENUS, 1874. HONOLULU.

•3

i t-i

*• 2.

Day.

Obsenrer.

Object

Altazimuth-
Clock Time
of Vertical
Transit over
Mean of
Horizontal
Wires.

3

! !
:§>

r5

Of

&

1

Reading of
Vertical
Circle
corrected for
Runs of
Micrometers.

Level Indication (a
ditive).

Barometer and E
ternal Thermomel

Refraction.

True observed
Zenith
Distance.

1875.
January 20

T

Moon's U. L. . . .

h m s

5.46.13-36

R

o / //
240. i. 33-8

75-3

3o"'-25

//

32-3

0 / //

29. 58. 9- 1

,, L. L. ...

5.48.41-30

R

240. i. 33-8

75-3

7i°-o

32-3

29. 58. 9- 1

NI

,, L. L. ...

9. 37.14-36

B

247.39.47-8

65-2

70° -I

23-o

22. 19. 55-9

,, U.L. ...

9. 39. 5z-o8

R

Z47- 39. 47 • 8

65-2

23-o

22. 19. 55-9

,, L.L. ...

10. 3. 9-74

B

242. i. 14-8

64-6

29-7

27.58.36-2

, , U. L. . . .

10. 5. 37'oz

R

242. i. 14-8

64*0

29-7

27. 58. 36-8

, , L. L. . . .

10. 14. 3i-34

R

239. 3i. 34-0

63-9

68°-z

33-o

3o. 28. 21-0

, , U. L. . . .

10. 1 6. 58-36

R

239. 3i. 34-0

63-6

33-o

30.28. 21-3

, , L. L. . . .

10. 27. 39-90

L

3o3. 20. 11-7

76-0

37-o

33.21. 38-8

, , U. L. . . .

10. 3o. 6-90

t

3o3. 20. 11-7

76-0

37-o

33.21. 38-8

,, L.L. ...

10. 39-21-58

L

3o5. 54. 3o-2

77-6

40-7

35.56. 2-6

, , U. L. . . .

10.41.49-45

L

3o5. 54. 3o-2

78-0

3o'"-22

40-7

35.56. 3-o

,, L. L. ...

10. Si. i3-5z

L

3o8. 3o. 39-0

78-2

67° -o

44'7

38.32. 16-0

, , U. L. . . .

10. 53.40'38

L

3o8. 3o. 39-0

78-6

44'7

38. 3z. 16-4

ZI

T

Pollux

u. 6.22-78
n. 14. 26-04

5.41.53-26

L

R

L

317.41.53-4
220. 3o. 34-9

314.28.47-9

78-6
68-0

70-6

70" -o

61-7
65-7

55-o

47.43.47-8
49.29.48-7

44. 3o. Z7'6

Moon's U. L. ...

,, L. L. ...

5. 44. 16-24

L

314.28.47-9

70-6

3oin-26

55-o

44. 3o. 27 -6

, , U. L. . . .

5. 5o. 0-28

L

3i2. 40. 3i -9

70-6

5i-7

42.42. 8-3

i

. r

January zi. The adopted Zenith point corresponding, to the mean wire is 270. o. 25-9

TABLE IX. — LONGITUDE FROM THE MOON'S OBSERVED ZENITH DISTANCE (continued). 183

Greenwich Mean
Solar Time,
assuming the West
Longitude to be
I. ioh. 3 1'". os.
II. lo1'. 3 11". o".

Tabular Geocentric Elements
(R. A. and N. P. D. corrected).

Hour-Angle.

Tabular Zenith
Distance of
Star or
of Limb of
Moon.

Inferred
Longitude
West of
Greenwich
ioh. 3im. +

Apparent
Kight
Ascension
of Center.

Apparent
North Polar
Distance
of Center.

Equatorial
Horizontal
Parallax.

Semi-
diameter.

h in s

o

/

0 / //

H

I. 20. 17. 0-57

7. 55.46-98

64. 7.23-5

58.22-3

15.55-9

32. 9.12-30

29.57.57-6

ii. 20. 18. 0-41

7.55.49-49

64. 7. 3o-5

58.22-3

iS.55-9

32. 9.49-95

29. 58. 3i-2

20-5

I. 20. 19. 28-11

7-55.53-17

64. 7. 40 • 6

58.22-2

iS.55-9

3i.33.46-o5

29.57.57-1

II. 20.20.27-95

7. 55. 55-67

64. 7.47-6

58. 22-2

iS.55-9

31.34-23-55

29. 58. 3o-5

21-6

I. o. 7. 33-92

8. 5.23-16

64. 35. 12-2

58. 16-9

i5.54-5

23. 14. 33 -3o

22.20. 8-5

II. o. 8.33-75

8. 5.25-64

64. 35. 19-7

58. 16-9

i5.54-5

23.i3.56-io

22. 19. 34-6

22-3

I. o. 10. 1-24

8. 5.29-26

64.35.30-7

58. 16-9

iS.54'5

23. 49. 57-60

22. 2O. 5 ' 9

II. o. ii. 1-07

8. 5.31-74

64.35. 38-2

58.i6-9

15.54-5

23.49. 20-40

22. 19. 31-9

I7-7

I. 0.33.15-09

8. 6.26-96

64.38.26-6

58. i6-3

iS.54'3

29. 24. $7' 1 5

27. 58.46-6

II. o. 34. 14-92

8. 6.29-43

64. 38. 34-2

58. i6-3

iS.54'3

29. 24. 20 -10

27.58. I2-7

18-4

I. o. 35.41-97

8. 6.33-o3

64. 38-45-2

58.16-3

1 5. 54-3

3o. o. i5-3o

27. 58. 5o-i

II. 0.36.41-80

8. 6. 35-5i

64. 38. 52-8

58. i6-3

iS.54'3

29. 59. 38-io

27. 58. 16-0

23-4

I. 0.44.34-82

8. 6.55-o8

64. 39. 52-9

58. 16-1

15.54-2

32. 8.19-35

3o. 28. 30-7

II. 0.45.34-66

8. 6.57-55

64. 40. o • 5

58. 16-1

15.54-2

32. 7.42-30

3o. 27. 56-9

17-2

I. 0.47. 1-45

8. 7. 1-14

64. 40. 1 1 • 5

58.i6-o

iS.54'2

32.43.33-75

30.28.32-7

II. 0.48. 1-28

8. 7. 3-6i

64. 40. 19-0

58.16-0

iS. 54-2

32.42. 56-70

3o. 27. 59-4

20-5

I. o. 57.41-24

8. 7.27-59

64.41. 33-i

58. i5-7

1 5. 54-1

35. 17.20-25

33.21. 5o-o

II. 0.58.41-08

8. 7. 3o-o6

64.41.40-7

58. i5-7

15.54-1

35. 16.43-20

33.21. i6-5

20- I

I. i. o. 7-84

8. 7.33-64

64. 41. 5i -8

58. iS-7

i5. 54-1

35. 52. 34- So

33.2i.53-5

II. I. I. 7-68

8. 7.36-12

64.41. Sg-S

58.i5-7

15.54-1

35. Si. 57-3o

33. 21. 20'O

26-3

I. I. 9. 22-00

8. 7.56-53

64.43. 2-7

58.15-5

15.54-1

38. 5.46-35

35.56. 16-2

II. i. 10. 21-83

8. 7.59-01

64. 43. 10*4

58.15-5

15.54-1

38. 5. 9-i5

35.55.42-8

24-4

I. 1.11.48-48

8. 8. 2-59

64.43.21-5

58. i5-4

15.54-0

38.40.58-65

35. 56. 18-1

II. 1.12.48-32

8. 8. 5-o6

64. 43. 29-2

58.i5-4

1 5. 54-0

38. 40. 21-60

35.55.44-7

27-1

I. I. 21. II'OI

8. 8.25-81

64.44. 33-8

58.15-2

i5. 54-0

40. 56. 11-40

38.32.25-8

II. 1.22. 10-85

8. 8.28-28

64. 44. 41 • 5

58. i5-2

i5. 54-0

40.55.34-35

38. 31.52-6

17-7

I. 1.23.37-47

8. 8.3i-86

64. 44. 52-6

58. i5-i

1 5. 54-0

41. 3i.23-55

38.32.26-7

II. 1.24.37-31

8. 8.34-33

64.45. o-3

58.I5-I

i5. 54-0

41. 30.46-50

38. 3i.53-7

l8'5

—

7. 37. 41 • 34

61. 40. 20-8

—

—

52.24.37-35

47.43.44-4

—

"

"

• —

—

54.25.26-25

49.29.47-2

I. 20. 8.46-46

8.53.37-98

67.34. 5-o

57.46-4

15.46-1

47.41.40-80

44. 3o. 3'4

II. 20. 9.46-30

8.53-40-31

67. 34. i5-2

57.46-4

15.46-1

47.42.15-75

44. 3o. 36 -9

43-3

I. 20. ii. 9'o5

8.53.43-52

67. 34. 29-3

57.46-3

i5. 46-1

47. 7.19-20

44. 3o. ii -2

II. 20.12. 8-89

8. 53.45-85

67.34.39-5

57.46-3

15.46-1

47. 7. 54- 1 5

44. 3o. 44-6

29-5

I. 20. 16. 52- 1 5

8.53.56-85

67.35.27-7

57.46-2

1 5. 46-1

45.44.38-55

42.41.43-1

II. 20. 17. 5i -99

8.53.59-I8

67.35.38-o

57.46-2

1 5. 46- 1

45.45. i3'5o

42. 42. i6-5

45-3

January 21. Aperture reduced. The observations of 5 U. L. have not been used.

184

TRANSIT OP VENUS, 1874. HONOLULU.

Day.

Observer.

Object.

Altazimuth-
Clock Time
of Vertical
Transit over
Mean of
Horizontal
Wires.

1

b
O

4

a

a

a

3

Beading of
Vertical
Circle
corrected for
Rung of
Micrometers.

Level Indication (ad-
ditive).

Barometer and Ex-
ternal Thermometer.

Refraction.

True observed
Zenith
Distance.

i87S.
January T.\

T

Moon's L. L. ...

h ni «

5. 52. 23-04

L

3 1 2. 40. 31-9

70-8

//
5i'7

42. 42. 8-5

, , U. L. . . .

5. 57. 9-34

t

3n. 4. 58-8 70-9

48-9

41. 6. 3i'7

i

„ L.L. ...

5.59.3i-82

I, 3n. 4-58-8

71-0

48*9 41. 6. 3z-S

j

,, U.L. ...

6. 8.39-38

R

231.27. 26-3

73-5

44-6

38. 32. 3o-7

j

, , U. L. . . .

6. 14. 40-70 n

232.48. 10-4

72-8

42-5

3y. u. 45-2

,, L. L. ...

6.17. 2-68 n

232. 48. 10-4

72-3

42' 5

37. ii. 45-2

„ U.L. ...

6.22.3o-58 K

234. 33. 21 -9

72-6

39-9

35. 26. 3i-3

, , L. L. . . .

6. 24. 52-32 R

234. 33. 21-9

72-4

39-9

35.26. 3i-5

, , U. L. . . .

6. 29. 49-76 K

236. u. 46-0

72-4

3y5

33.48. 5-o

, , L. L. . . .

6. 3z. 11-48

6.38.35-74
6.45. 3-46
6. 5z. 26-92

R

K
R

L

236. ii. 46-0
221. 4. 34-0

222. 34.47-8

3i5. 40. 3; -5

72-4
71-2

71 '2
69-6

3o"'-26

37-5

64-3
61-0

57-4

33.48. 5-o

48. 55.45-0
47.25.27-9
45. 42. 18-6

"

6.57.33'44 L 314.29.24-6

7O-6

69°- 3

55-i

44- 3i. 4-4

22

T

Moon's L. L. ...

8. ii. 36-78

L

294. 3o. 44- 1

70-6

i.S-5

24. 3i. 54-3

,,

8. 16.42-68

D

293. 21. 3o- 1

71-0

24-1

23.22. 38-3

,,

8.20. 39-68

L

292. 27. 57-7

71-0

z3-i

22. 29. 5'9

> > ...

8.25. 18-68

R

248. 33.28-7

71-6

7i°-5

21-9

21.26. 7'5

,,

8. 3o. 9-20

U

249. 33. 53-7

70-6

20-7

2O. 2O. 42-3

, , ...

8. 34. 37-96

R

25o. 3g. 16-4

70-6

19-6

19. 2O. l8'5

o / //

January 22. The adopted Zenith point corresponding to the mean wire is 270. o. 25-9

TABLE IX. — LONGITUDE FROM THE MOON'S OBSERVED ZENITH DISTANCE (continued}. 185

Greenwich Mean
Solar Time,
assuming the West
Longitude to he
I. io]l. 3 1'". os.
II. ioh. 32'". o".

Tabular Geocentric Elements
(K, A. and N. P. D. corrected).

Tabular /enith
Distance of
Hour- Angle. Star or
of Limb of

MOOD.

|

Inferred
Longitude
West of
Greenwich
loh. 3 1'". +

Apparent
Right
Ascension
of Center.

Apparent
North Polar
Distance
of Center.

Equatorial
Horizontal
Parallax.

Semi -
diameter.

h m s

h m K

/ //

/ //

o / //

0 / //

I. 20. 1<). 14' 52

8. 54. 2" 39

67. 35. 52-o

57.46-1

i5. 46- 1

45. IO. 2O-25

42.41. 5i-3

II. 20. 20. 14' 35 I 8.54. 4' 71

67. 36. 2-3

57.46-1

15.46-1

45. 10. 55-o5

42.42. 24-7

3o'9

I. 20.24. °'°4 8.54.13-47

67. 36.40-8

57.46-0 15.46-0

44. I. 3i -95

41. 6. 7-2

II. 20.24.59-88 8.54.15-80
I. 20.26.22-13 8.54.18-99

67. 36.*5i-o
67.37. 5-o

57.46-0 15.46-0
57.45-9 15.46-0

44. 2. 6-90
43.27.I7-55

41. 6.40-4
41. 6. 16-7

46-1

II. 2O. 27. 21 '97

8.54.2I-31

67. 37. i5-3

57.45-9 15.46-0

43.27.52-35

41. 6. 5o-o

29-0

1. 20.35.28-21

8. 54.40-18

67. 38. 38-4

57.45-6 | 15.45-9

41. 15.4I-85

38.32. 4-9

11. 20. 36. 28-04

8. 54. 42- 5o

67. 38.48-7

57.45-6

15.45-9

41. 16. i6'65

38.32.38-o

46-8

I. 20. 41. 28- 54

8. 54. 54-16

67. 39. 40' I

57-45-5

15.45-9

39.48. 5i-6o

37.11.17-5

11. 20.42.28-38

8. 54. 56- 5o

67.39.50-4 57.45-5 15.45-9

39. 49. 26-70

37. ii. 50-9

5o- 1

1. 20.43. 50-14

8. 54. 59-65

67.40. 4-4 57.45-4

I5.45-9

39. 14.44-25

37. 11.28-7

II. 20.44.49-98

8.55. 1-97

67.40.14-7 57.45-4

15.45-9

3g. i5. 19-05

37.12. 1-8

29-9

I. 20. 49. 17*14

8. 55. 12-33

67.41. o-5 57.45-3 15.45-8

37. 55. 55-95

35.26. 5-8

.

1!. 20. 5o. 16-98

8. 55. 14-65

67.41. 10-8

57.45-3 15.45-8

37. 56.3o-75

35.26.38-9

46-2

1. 20. 5i.38-5o

8. 55. 17-82

67.41. 24-8

57.45-2 15.45-8

37.21. 52'20

35.26. 18-1

11. 20.52.38-33

8. 55.20-14

67.41. 35-o

57.45-2 r5.45-S

37. 22. 27-00

35.26. 5l'2

24-3

1. 20. 56. 44-97

8. 55. 29-69

67. 42. 17-4

57.45-1 i5.45-8

36. 10. 28 -So

33.47.44-4

11. 20. 57. 44-80

8. 55. 32-oi

67.42. 27-7

57.45-1 iS-45-8

36.il. 3-3o 33.48.17-1

37-8

1. 20. 58. 56-46 8.55.34-79

67. 42. 40-0

57.45-0 15.45-8

35.36.19-20 ! 33.47.49-4

11. 2o.59-56-3o

8. 55. 37-11

67.42. So- 3

57.45-0

i5.45-8

35. 36. 54- oo

33.48.22-3

28-5

10. 1.43-93

77.25.23-i

—

—

So. 32. 32-40

48. 55.46-2

—

,,

> »

—

—

48.55.36-6o 47.25.30-9

—

,,

M

—

—

47. 4.44-55 45.42.20-1

—

• »

• I

—

—

45.48. 6-60

44. 3i. 3-6

—

1. 22. 34. lO-gi

9. 52. 3o-63

72. 39. i3-8

57. 1-8

i5. 34-0

24. 58. 37-20 24. 3i. 34-1

II. 22.35.10-74

9. 52. 32-75

72. 39. 26-5

57. 1-8

1 5. 34-0

24. 59. 9-00 24. 32. 6-8

37-i

I. 22. 39. l6'OI

9. 52.41-44

72. 40. 18' 3

57. I -6

iS.33'9

23.44.5o-7O | 23.22.21*3

11. 22. 40. 15-84

9. 52.43-57

72. 40. 3o'9

57- 1-6

i5. 33-9

23-45.22-65 i 23.22. 53-6

3i-6

1. 22.43. 12-33

9. 52.49-83

72.41. 8-3

57. 1-5

15.33-9

22.47.41-55 I 22.28.48-2

11. 22. 44. 12-17

9. 52. Si-gS

72. 41. 20-9

5 7. i-5

i5. 33-9

22.48.13-35 22.29.20-9

32-5

I. 22. 47. 5o'57

9. 52. 59-69

72.42. 7-2

57. 1-4

i5. 33-9

21.40.24-45 21.25. 5o-7

11. 22. 48. 50-41

9.53. 1-81

72.42. 19-8

57. 1-4

iS.33'9

21.40.56-25 21.26.23-5

3o-7

1. 22. 52. 40-29

9.53. 9-97

72.43. 8-5

57. i-3

i5. 33-8

20. 3o. 20-85 20.20.24-5

11. 22.53.40-I3

9. 53. 12-09

72.43. 21 "I

57. i-3

15. 33-8

20. 3o. 52-65 20.20.57-0

32-9

\. 22.57. 8'H

9. 53. 19-46

72.44. 5-2

57. i-i

15.33-8

19. 25. 3i-65 | 19. 20. o-o

11. 22.58. 8-17 9.53.21-58

72.44. 17-9

57. i-i

i5. 33-8

19. 26. 3-45 19. 20. 32'7

33-9

January 22. Aperture reduced.

186

TRANSIT OF VENUS, 1874. HONOLULU.

Day.

Observer.

Object.

Altazimuth-
Clock Time
of Vertical
Transit over
Mean of
Horizontal
Wires.

g
1

O.
|

Reading of
Vertical
Circle
corrected for
Runs of
Micrometers.

Level Indication (ad-
ditive).

Barometer and Ex-
ternal Thermometer.

Refraction.

Tree observed
Zenith
Distance.

1875.
January 22

23

T
KI

j8 Ixjonis ....

h m s

8.44.41-44
8. 50.41-96
9. 5.19-88
9. ii. 23-78

6. ii. 24-82

R
R
L
L

L

o / //

227.41. 3-o
229. 4. 59-2
307. 29. ii -5
3o6. 4. 36'- 6

334.41. 18-0

70-6
71-2
71-8
72-0

76-3

3o'"-2o
7i°-3

65°-3

5o-8
48-3
42-8
40-7

118-2

0 / ft

42. 19. 3-1

40.55. 3-8
37. 30.40-2
36. 6. 3-4

64. 44. 3 - 6

Moon's L. L. ...

,,

6. 19.44-94

t

332.48.45-3

76-6

109-0

62. 5l. 22'O

1 1 • • •

6. 27. 21-96

L

33i. 5.48-7

77-0

loi'S

61. 8. i8-3

,,

6. 37. 16-80

R

211. 6. 54-5

66-0

64° -6

92-9

58.54. 0-7

,,

6.44. 29-22

R

212.44. 33-3

65-8

3o'"-i4

87-2

57. 16. 17-0

,,

6.53.27-88

R

214.46. 14-2

64-8

64° -o

80-9

55. 14. 3o-8

24

NI

5 Leonis

7. 4.55-26
7. iS.25-86

7.40.58-48

R
t

L

214. 6.40-3
323.28. 9-1

327. 9. 7-2

64-4

75-6

79-0

60° -6

82-9

87-6

55. 54. 7-1
53. 3o. 11-7

57. 11.24-9

Moon's L. L. ...

„

7. 53. 31-04

L

324. 20. 25-8

80-4

78-9

54.22. 36-2

>

8. i. 50-46

8. 10. 10-28
8. i8.5i-i6
8. 27. 39-60

L

L
R
R

322.28.43-5

320. 18.49-4
221.40. 5i"5

223. 14. I2'6

80-6

81-2
66-5
65-i

£

73-8

68-4
63-7
6o-3

52. 3o. 49 -o

5o. 20. 5o-i
48. 19. 34-6
46. 46. ii -5

Moon's L. L. ...

,,

8.37.33-40

R

225.25. 9'5

64-7

3oln-n

55-9

44. 35. 10-6

"

8.46.25-68

R

227. 21.48-9

64-3

59° -3

52-2

42. 38.27-9

25

NI

Moon's L. L. ...

8.31.47-24

R

211.42. 3i'8

66-6

66° -9

90-5

58. 18.21-0

o / //

January 23 and 24. The adopted Zenith point corresponding to the mean -wire is 270. o. 28-9

TABLE IX.— LONGITUDE FROM THE MOON'S OBSERVED ZENITH DISTANCE (continued}. 187

Greenwich Mean
Solar Time,
assuming the West
Longitude to be
I. ioh. 3 1"1. o».

II. I0h. 32"'. 0s.

Tabular Geocentric Elements
(R. A. and N. P. D. corrected).

Hour-Angle.

Tabular Zenith
Distance of
Star or
of Limb of
Moon.

Inferred
Longitude
West of
Greenwich
ioh. 3im. +

Apparent Apparent
Kight North Polar
Ascension Distance
of Center. of Center.

Equatorial
Horizontal
Parallax.

Semi-
diameter.

h

h

o / //

/ //

/ //

0 / //

0 / //

8

—

II. 42. 41*78

74.43. 52-7

—

—

44. i5. 14-25

42. 19. 0-9

—

—

, ,

> )

—

—

42.4$. 6-45

40.55. 2-3

—

—

>1

,,

—

—

39. 5. 37-5o

37. 3o. 39-7

—

"

» »

—

—

37. 34. 39-00

36. 6. 0-2

I. 20. 3o. 23*90

10. 37. 34-40

77. 3i. 52-9

56.23-7

iS.23-5

66. 17. i5-6o

64.43.47-6

II. io.3i.23'73

10. 37-36-38

77.32. 6-7

56.23-7

iS.23-5

66. 17.45-30

64.44. '9'4

3o-2

I. 20.38.42-66

10. 37. 5o"9i

77.33.48-3

56.23-4

iS.23-5

64. 16. 21 -3o

62. Si. 6-6

II. 20. 39. 42- So

10. 37. 52-88

77.34. 2-2

56.23-4

iS.23-5

64. 16. So-85

62. Si.38-3

29-2

I. 20. 46. I8-43

10.38. 5-98

77-35.33-9

56.23-2

iS.23-4

62.25. 52- oS

61. 8. i-o

II. 2O. 47. l8'27

10.38. 7-96

77.35.47-7

56.23-2

i5. 23-4

62. 26. 21-75

61. 8.32-9

32-5

I. 20. 56. n-66

10. 38. 25-59

77. 37. Si- 3

56. 22-9

iS.23-3

60. 2. 3-45

58. 53.41-7

II. 20. Sj. 1 1 '49

10. 38.27-57

77-38. 5-2

56. 22-9

iS.23-3

60. 2. 33-i5

58.54. i3'6

35-7

I. 21. 3.22-91

10. 38. 39-85

77.39.31-2

56.22-7

iS.23-3

58. 17. 30-90

S7.i5.57-9

II. 21. 4. 22-75

10. 38.41-82

77.39.45-1

56.22-7

iS.23-3

58. 18. 0-45

57. 16.29-7

36-o

I. 21. 12. 20-09

10. 38. 57-59

77.4i.35-8

56.22-5

lS.23'2

56. 7. 17-10

55.14. 8-7

II. 21. i3. 19-93

10. 38. 59-57

77.41.49-7

56.22-5

lS.23'2

56. 7.46-80

55. 14. 40-0

42-4

n. 7. 28-62

68.47.37-3

—

—

60. 23. 11-70

55.54. 7-1

—

"

> >

—

—

57.45. 32-55

53. 3o. 11-7

—

I. 21.55.48-02

n. 26. 25- 17

83.34.21-9

55.41-7

i5. 12-1

56. 6.16- So

57.11. 8-z

II. 21.56.47-86

ii. 26. 27-03

83.34-36-3

55.4i-7

i5. 12- 1

56. 6.44-40

57. 11.39-3

32-2

I. 22. 8.18-52

ii. 26. 48- 5o

83.37.23-4

55.41-4

l5. I2'0

53. 3. 58-o5

54. 22. l6'5

II. 22. 9.18-36

ii. 26. 5o-36

83.37. 37-8

55.41-4

i5. 12-0

53. 4.25-95

54.22.47-S

38-1

I. 22.16.36-58

11.27. 3-97

83.39.23-8

55.41-2

i5. ii -9

Si. 2. 58-8o

52. 3o. 29-7

II. 22. 17. 36-42

11.27. 5-83

83.39.38-3

55.41-2

1 5. 11-9

Si. 3/26-70

52. 3i. 0-7

37-i

ii. 42. 41-83

74.43. 52-9

—

—

52. 52. 29-25

So. 20. 48- 1

—

> *

» »

—

—

50.42. i6-oS

48. 19. 33-6

—

I. 22.42.2I-5O

ii. 27. Si'95

83.45.3y-6

55.40-5

i5. 11-7

44.47.41-25

46. 45.49-6

II. 22.43.21-34

ii. 27. 53-8i

83.45.52-o

55.40-5

iS. 11-7

44.48. 9'i5

46. 46. 20 -7

42-2

I. 22.52.13-68

n. 28. io- 34

83.48. 0-9

55. 40-2

iS. 11-7

42. 23. So'io

44. 34.49-5

II. 22. 53. i3-5i

II. 28. I2-2O

83. 48. i5-3

55. 40-2

i5. 11-7

42. 24. 1 8 • oo

44. 35. 20- 7

40-6

I. 23. i. 4'5o

ii. 28. 26-81

83. So. 9-3

55.40-0

i5. n-6

40. 14. $2-95

42.38. 5-2

II. 23. 2. 4-34

11.28. 28-67

83. So. 23-8

55.40-0

i5. 11-6

40. iS. 20-85

42.38. 37-6

42-0

I. 22.42.33-28

12. II.43-47

89.34.52-5

55. 6-3

1 5. 2-~5

54.43.28-50

58. 18. o-3

II. 22.43.33-n

12. II. 45-26

89.35. 6-9 55. 6-3

i5. 2-5

54.43.55-35

58. 18. 3o-8

40-7

January 23. Aperture reduced.

B B

188

TRANSIT OF VENUS, 1874. HONOLULU.

Day.

Observer.

Object.

Altazimuth-
Clock Time
of Vertical
Transit over
Mean of
Horizontal
Wires.

Lamp Right or Left.

Reading of
Vertical
Circle
corrected for
Huns of
Micrometers.

Level Indication (ad-
ditive).

Barometer and Ex-
ternal Thermometer.

Refraction.

True observed
Zenith
Distance.

1875.
January zS

NI

Moon's L. L. ...

8.40. 15-98

R

0 / //
213. 33.47-7

//
65-S

84-3

0 / //

56.26. 59-7

i y ...

8. 49. 39 • 74

R

2i5. 36.28-2

66-0

78-1

54. 24. 12-8

, , ...

8. 59. 46-92

r,

322. 10. 5o- 1

75-8

67° -3

72-1

52. 12. 49'I

, , ...

9. 8. 30-70

L

320. 18.28-4

76-6

3o"'-i6

67-4

So. 20. 23-5

27

XI

, , ...

9. 17. 31-04

9. 3i. 56-40
9. 40. 54- 16

9. 1 3. 34-78
9. 21. 28-24
9.29.43-58

9.37.39-34
9. 46. 40-46

Xi

L

R

L
L
K
R
R

3i8.23. 3i-9

333.48.48-4
208. S.iS-5

337.44. i°'4
336. 2.18-2
205.42. 5-6

2O7. 22. 48-7

2o3. 3o. 38 -j

77-0

77-6
67-0

83-i
83-o
60-0
59-6
59-6

67° '9
67°-9

65°-4

63 'o

113-4

104-6

136-4
J25-7
116-0 •
107-9
128-9

48.2$. 23-o

63. 5i. 3o-5
61. 57. 48-0

67.47. I' '0

66. 5.iS-o
64. 19. 19-3
62. 38.28-5
66. 3i. o- 1

Moon's L. L. ...

> > • • '

9. 55. i- 14

R

2o5. i3. 16-9

58-8

119-2

64.48. 12-4

> > ...

10. 2. 27-62

R

206. 44 2*4

58-4

64° -9

,
III • 6

63. 17. 19-7

> > • ' '

10. 10. 4-64

I>

33i. 42. 26-4

Si-o

104-6

61.45. 3-i

, , ...

10. 18. 38-40

L

33o. o. 2-0

8i-5

3olu-j3

97-0

60. ;. 3 1 -6

February 5

T

> > ...
S Leonis

10. 26. 26-08

7-58. 38-io
8. 6. 10-90
9. 3o. 10-84
9. 37. 2o-32

L

L
R

L
R

328.27. 55-6

3i3. 3i. 24-4
228. ii. 19-8
325.26. 6-8

212. 52. 47'2

82-2

87-7
58-i
5g-S
87-8

65°-9

59° -i
3o'" • oo

58° -o

91-2

53-8
So- 6
82-2
8y5

58. 3o. 20- 1

43. 33. 20-5
41.48. 58-i
55.28. 3-4
57. 7.37-9

0 / //

January 27. The adopted Zenith point corresponding to the mean wire is 270. o. 28 '9
February 5, 270°. o'. 25"'4. The two stars were observed for clock-error ; the hour-angles have been computed from
the observed zenith-distances.

TABLE IX. — LONGITUDE FROM THE MOON'S OBSERVED ZENITH DISTANCE (concluded). 189

Greenwich Mean
Solar Time,
assuming the West
Longitude to be
T. lo1'. 3i"'. o".

II. I0\ 32'". 0".

Tabular Geocentric Elements
(H. A. and N. P. D. corrected).

Hour-Angle.

Tabular Zenith
Distance of
Star or
of Limb of
Moon.

Inferred
Longitude
West of
Greenwich
ioh. 3 1"1. +

Apparent
Right
Ascension
of Center.

Apparent
North Polar
Distance
of Center.

Equatorial
Horizontal
Parallax.

Semi-
diameter.

ll 111 S

h in 14

0 f ft

/ //

Off/

o / //

I. 22. Si. 0-64

12. ii. 58-68

89. 36. 55-i

55. 6-1

i5. 2-4

52.40. 5-40

56.26.37-7

II. 22. 52. 0-48

12. 12. O"47

89.37. 9'5

55. 6-1

i5. 2-4

52. 40. 32'25

56.27. 8-1

43-4

I. 2J. O. z3* II

12. 12. l5'54

89. 39. n-o

55.' 5-9

i5. 2-3

So. 23. 21 '7?

54. 23. 52-4

II. 23. I. 22-95

12. 12. I7-34

89. 39.25-4

55. 5-9

i5. 2-3

50.23.48-75

54. 24. 23-0

40-0

f. 2J. 10. 28-41

12. 12. 33-69

89.41. 37-2

55. 5-7

i5. 2-3

47.56. 6-iS

52.i2.33-6

II. 23.11.28-25

12. 12. 35-49

89.41. Si'7

55. 5-7

i5. 2-3

47. 56. 33- 1 5

52. 1 3. 4-2

30-4

I. 23. 19. 10.76

12. 12. 49- 34

89.43.43-4

55. 5-5

i5. 2-2

45.49. 4-20

So. 20. 8-8

II. 23. 20. 10' 59

12. 12. 5l ' 14

89.43. 57-9

55. 5-5

l5. 2-2

45. 49. 3 1 -20

5o. 20. 39-6

28-6

I. 23.28. 9-63

12. 13. 5'5o

89.45. 53-6

55. 5-3

l5. 2'2

43.38. i-35

48.25. 8-9

II. 23.29. 9-47

12. i3. 7-29

89.46. 8-0

55. 5-3

l5. 2'2

43. 38.28-20

48. 25. 39-4

27-7

•

i3. 18. 36-68

100. 3o. 33'i

—

—

56.24.28-50

63.5i. Ji-3

—

^~~~"

"

"

—

—

$4. 10. i-gS

61. 57.48-6

—

i3. 18. 36-75

100. 3o. 33-5

—

—

60. 59. 22- 35

67.47.21-9

,,

» »

—

— •

$9. i. o-3o

66. 5. 18-0

—

» »

,,

—

—

56. $7. 10-20

64. 19.20-9

—

, ,

, ,

—

—

54. 58. i3-65

62. 38.26-6

—

I. 23. 49. 24-59

i3. 39. 38-o3

loo. 59. 56-o

54.21-3

14. 5o- 1

57. 58. 15-90

66. 3o. 40-4

II. 23. 5o. 24-43

13.39.39-83

101. o. 9-1

54.21-3

14. So- 1

57. 58.42-90

66. 3i. io'o

39-9

I. 23. 57. 43-90

i3. 39. 53-10

101. 1.45-2

54. 21-2

14. So- 1

55.56.51-75

64.47. 52-2

II. 23.58.43-73

i3. 39. 54-91

101. i. 58-2

54. 21-2

14. So- 1

55. 57. 18-90

64. 48. 21-7

41-1

I. o. 5. 9-17

13.40. 6-58

IOI. 3. 22'9

54. 21-2

14. So- 1

54. 8.36-6o

63.17. o-3

II. o. 6. 9-01

13.40. 8-39

101. 3.35-9

54. 21-2

14. So- 1

54. 9. 3-75

63. 17. 29-8

39-5

I. 0.12.44-94

1 3. 40. 20-34

101. 5. 2-4

54. 21- I

14. So- 1

52. 17.47-70

61.44.49-7

II. 0.13.44-78

13.40. 22- 1 5

101. 5. i5-5

54. 21 'I

14. 5o-i

52.18.14-85

61. 45. 19-2

27-3

I. 0.21.17-31

13.40. 35-82

101. 6. 54-3

54. 21 -O

14. So- 1

So. i3. i3-35

60. 2. 19-3

II. O. 22. 17 * 14

13.40. 3?-63

101. 7. 7-3

54. 21 'O

14. So1 1

So. 13.40-50

60. 2.48-7

25-1

[. 0.29. 3-72

1 3. 40. 49-91

101. S. 36-i

54. 21 -O

14. 5o-o

48. 19. 49- 35

58. 3o. 7-5

II. o. 3o. 3-55

1 3. 40. Si -71

101. 8.49-1

$4. 21 -O

14. 5o-o

48. 20. 16- 35

58. 3o. 36-6

26-0

ii. 7.28-93

68.47. 38-i

__

—

46. 54. 59-4

—

, ,

, ,

—

—

45. 1.41-0

—

5.48.25-18

82.37. o'9

—

55. 44. 11-7

—

» >

> *

57.3i. 33-o

January 25. Aperture reduced. January 27. Spica unsteady.

\

B B 2

190

TRANSIT OF VENUS, 1874. HONOLULU.

TABLE X. — LONGITUDE of HONOLULU from the OBSERVED EIGHT ASCENSION of the MOON on the

MERIDIAN.

served.

Observed
E.A. of

Longitude by the
Ephemeris.

Adopted

Resulting

Day.

B

•§

Moon's Limb

e = the correction

Value

Longitude, *j

C

V

1

I

on the
Meridian.

required to the Moon's
Tabular R.A.

Off.

West.

.SP
'S

hfc

o

3

P-

1874.

it m s h m s

i

h ,» .

Oct. 17

T

I.

19. 29. I '29

10.31.14-86 — 24-366 —0-34

10. 3i. 23' i 6

Good observation, seven

minutes after sunset. Clock

correction depends upon

three stars near the moon.

18

T

I.

2O. 27. 48'39

16-16 — 24-71 e

•37

25-3

3

Cloudy. Moon observed on

two wires only. Clock

correction depends upon

three stars near the moon.

]9

NO

I.

21. 25. 19-81

11-93 — 25- 39 e

'4>

22 '3

6

Good observation.

20

B

I.

22. 21. I7'43

23-71 — 26-06 f

'44

35-2

3

Cloudy. Clock correction un-

satisfactory.

21

T

I.

23. l6. 2-32

9-26 — 26-47 t

'47

21-7

5

Good observation.

23

T

I.

I. 5.S4-49

14-07 — 25- 59 f

•63

30'2

5| i Good observation.

24

NO

II.

2. 3.3i-i3

20-24 — 24-38 e

•72

37'8

3 \ Moon observed at four wires,

which are discordant ; mi-

crometer-reading doubtful.

Bad night. Observer

fatigued.

a?

NO

II.

5. 17.52-31

3o. Sg'S? — 21-42 e

•89

18-6

4

Tremor. Clock correction

depends upon two stars near

the moon, and is not satis-

factory.

Nov. 1 5

NO

I.

21. 4. 26-52

3i. 23-03-25-88 e

•32

3i-3

54

Wires are discordant. Sun

just set.

16

T

I.

21. 5g. 8-58

15-25 — 26-76 «

•32

23-8

5

Good observation.

22

T

I.

3.32.57-73

12-72—22-31 e

•65

27-2

7

Good observation.

„

J>

II.

3. 35.28-o5

1 5 • 42 — 22 • 3 1 e

•65

29-9

H

Good observation. Correc-

tion for defective illumina-

tion, + O*'28.

23

T

II.

4.41. 55-76

i3-55 — 21-17 e

'74

29-2

8

Good observation. Some

tremor.

27

T

II.

9. i.25-8i

9-00 — 25-72 €

•83

3o-4

5*

Observer fatigued.

28

R

II.

9.54.47-44

5-09 — 28-29 e

•78

27-2

4

Some tremor, but good obser-

vation.

29

T

II.

10.43. 38-oo

4-29 — 30-64 6

•7i

26'O

4

Much tremor. Fair observa-

tion, 14 minutes before sun-

rise. Clock correction very

satisfactory. Noisy gale.

Dec. i

T

II.

12. 12. 55-70

9-99— 33-3o «

•60

3o'o

4

One hour after sunrise. Limb

bright and steady. The

clock correction was deter-

mined 10 hours before the

observation of the moon.

Clock-rate very steady.

2

T

II.

12. 55. 59-29

8-01-33-39 «

•14

26-0

4

if hours after sunrise. Limb

fairly bright and steady.

The clock correction was

determined 12 hours after

the observation of the moon.

Clock-rate very steady.

'4

K

I.

22. 34. 5l-87

14-75-27-83 f

•35

24-5

5

The wires are discordant ; 1 7

minutes before sunset.

i5

NO

I.

23.26. 2-41

2-58 — 28-72 €

•36

12-9

4i

Good observation.

16

K

I.

o. 1 6. 54-67

I9-l5 — 28-l6 €

•39

3o-i

4i

Good observation.

'7

NO

I.

i. 8. 5o'97

10. 3i. 16-04 — 27 -19*

-0-43

10. 3i. 27-7

5

Through clouds. Clock cor-

rection satisfactory.

TABLE X. — LONGITUDE FROM THE MERIDIONAL TRANSITS OF THE MOON.

191

;J

5
>

8

Observed
R.A. of

Longitude by the
Ephemeris.

Adopted

Resulting

Day.

K

^

Q

Moon's Limb

e = the correction

Value

Longitude,

_£j

.

E
J

.=

e

on the
Meridian.

required to the Moon's
Tabular R.A.

of e.

West.

H>
'3

5

3

f

1874.

h m »

L m s

i

h in s

Dec. 1 8

R

i.

2. 3.20-60

10. 3i. 12-80 — 25-61 e

-0-48

10. 3i. 25- 1

5*

Good observation.

'9

NO

i.

3. 1.43-31

8-3i — 23-74 €

•53

20-9

5

Raining. Much tremor. Clock

correction satisfactory.

20

NO

i.

4. 4.41-35

16-57 — 22-09 f

•60

29-8

74

Good observation.

21

T

i.

5. ii. 38-o5

12-86 — 21-08 e

•70

27-6

8

Three wires only, and through

cloud.

ii.

5. 14. 12-62

12-88-21-08 €

•70

27-8

4

Limb faint, through cloud ;

1 8 hours be/ore full moon.

Correction for defective illu-

mination, + Is -40.

22

NO

i.

6. 20. 18-40

8-41 — 2I'o5 e

'79

25-o

8

Good observation. Correction

for defective illumination,

-0s- 12.

>»

»»

ii.

6. 22. 52-96

6-3i — 2i-o5 f

•79

22-9

8

Good observation.

*4

B

ii.

8. 32.43-03

8-87-23-98 e

•86

29-5

6

Good observation.

29

T

n.

12. 38. 49-22

8-95-33-i5 e

•61

29-2

Ji

Good observation.

3o

NO

ii.

l3. 22. 2I-93

2-3o-32-8z e

•So

18-7

H

Good observation, just after

sunrise.

3i

T

ii.

14. 6. 57- 16

io-i3 — 3i-66 e

•42

23-4

4

Good observation, 40 minutes

after sunrise ; limb bright

and steady.

i875.

Jan. i

T

ii.

14. 53. 39-08

9-88 — 29-94 e

•35

20-4

4

Wires are discordant. Obser-

vation labours after sunrise.

i3

T

i.

o. 52. 4- ii

1 2 • 90 — 28 • 04 e

•42

24-7

3

Indifferent observation ; four

wires.

'4

It

i.

1.44.27-79

14- I7 — 26-73 €

•45

26-2

5

Two wires only. Limb steady.

i5

R

i.

2. 39.47-II

l6- 12 — 25" l8 6

•49

28-5

6

Good observation.

16

R

i.

3.39. 3-99

16-41 — 23-44 e

•53

28-8

61

Good observation.

'7

R

i.

4. 42. 3o'o7

22 -3o — 22 -08 e

•56

34-7

H

One wire only. Clock cor-

rection satisfactory.

18

K

i.

5.48. 53-96

16-09 — 21-45 f

•59

28-7

8

Good observation. Limb

steady.

'9

T

i.

6.55.45-I2

II "98 — 21 -79 €

•61

25-3

74

Good observation. Some

tremor.

20

R

i.

8. o. 9 -56

9 '00 — 23-08 e

•62

23-3

7

Good observation. Some

tremor.

,»

„

ii.

8. 2.36-87

9-02 — 23-08 «

•62

23-3

H

Good observation. Some

tremor. Correction for de-

fective illumination, + os'o7.

22

K

ii.

9.57.18-37

12-14 — 27-59 e

•60

28-7

44

Good observation.

23

NO

ii.

10.47. 3g-38

4-76-29-73 f

•57

21-7

4

Good observation.

24

R

ii.

ii. 34. 38-47

14-49 — 3i'5o f

•54

3i-5

34

Good observation.

25

T

ii.

12. 19. 30-69

12-66 — 32-47 f

•So

28-9

H

Good observation.

26

T

ii.

i3. 3.32-12

i6-36-32'73 f

•46

3i-4

3

Overcast ; raining. Clock cor-

rection satisfactory.

27

T

ii.

13.47.54-34

i3'45— 32-o3 e

.-42

26-9

3i

Good observation.

28

T

n.

14. 33.44-81

16-89 — 30-71 e

•39

28-9

31

Good observation.

29

T

ii.

l5. 22. 2-27

l3-3o-28'92 f

•38

24-3

4l

Good observation, 10 minutes

after sunrise.

3o

T

16. i3. 3i-oi

l5-97 — 27-o6 €

•3?

26-0

5

Good observation, one hour

after sunrise ; limb bright

and steady.

3i

K

ii.

17. 8. 26-02

10. 3i. 12^70 — 25-41 (

-o-36

10. 3i. 21-9

Si

Tremor ; limb pretty bright ;

ij hours after sunrise.

See page 2 3 for mean results.

192

TRANSIT OF VENUS, 1874. HONOLULU.

TABLE XI — ABSTRACT of LONGITUDES of HONOLULU from the observed ZENITH DISTANCES of the

MOON'S FIRST LIMB, i.e., U.L. when East, L.L. when West of the Meridian.

Day.

Observer.

No. of
Obser-
vations.

Mean inferred
Longitude from
each Day's
Observations.

Correction to
Longitude for
the Distance
between the
Instruments.

Seconds of
Corrected
Longitude.

Weight.

1874-5.
October i S

T

4

h in s

10. 3i. z5'2

i

+ 2'O

27-2

6

Z. D. about 81°.

<7

NI

3

9'4

1-6

11-4

0

Z. D. about 82°.

18

T

6

26-7

i-5

28-2

5

Z. D. about 80°.

'9

KI

6

9'4

i'4

10-8

IO

21

NI

8

18-4

1*4

19-8

i3

22

M

6

17-9

1-6

i9-5

'4

23

T

8

25-5

i-5

27-0

'4

23

HI

4

21-6

1-6

23-2

H

24

M

6

28-1

1-6

29-7

'4

November 14

n

4

24 'o

1-6

25-6

5

Z. D. about 84°.

iS

NI

6

22'7

1-6

24-3

10

16

22

NI

KI

4
6

23-o

17-7

1-6
«'7

24 '6
19-4

II

i3

First four observations
rejected.

December J4

M

6

19-3

i-5

21-8

n*

i5

NI

6

24-5

1-6

26-1

12

18

NI

6

29-5

i'7

3l'2

i3

'9

NI

6

24-7

l~1

26-4

i3

20

NI

6

26-6

1-6

28-2

i3

21

n

6

27-5

1-6

29-1

i3

22

T

6

18-1

1-6

19-7

0*

Defective limb.

January 1 1

T

6

29-O

1-6

3o'6

12

i3

KI

6

35-9

1-7

37'6

12

'4

NI

6

34-2

«*7

35-9

12

i5

T

6

23-1

i-g

24-9

12

16

n

6

27-4

i'7

29-1

12

i?

XI

6

23-1

»*7

24-8

10

18

NI

6

25-7

1-6

27-3

13

'9

NI

6

23;9

"'7

25-6

12

'9

T

8

18-6

i'7

20-3

12

20

T

6

19' 6

>'7

21-3

12

20

KI

6

IO. 3l. 20'O

+ 1-7

tt'7

12

Mean, wjfh weights, of corrected Longitudes

t m K

o. 3i. 25-5 (see page 27).
1

TABLE XI. — ABSTRACT OF LONGITUDES FKOM THE MOON'S ZENITH DISTANCE. 193

TABLE XI. (continued). — ABSTBACT of LONGITUDES of HONOLULU from the observed ZENITH DISTANCES
of the MOON'S SECOND LMB, i.e., L.L. when East, U.L. when West of the Meridian.

Day.

Observer.

No. of
Obser-
vations.

Meau inferred
Longitude from
eacli Day's
Observations.

Correction to
Longitude for
the Distance
between the
Instruments.

Seconds of
Corrected
Longitude.

Weight.

.874-5.
October 3

T

6

h in 5

10. 3i. I9'o

+ 1-9

20' 9

5*

4

NI

6

22-8

2'O

24-8

5*

5

la

6

27-8

2'O

29-8

5*

7

T

6

28-7

of

25

T

8

28-3

i-6

29-9

'4

2.6

T

6

3o-6

''7

32-3

12

26

n

6

24-1

1-6

25-7

i3

27

T

4

i8-«

1-6

19-8

12

27

HI

6

16-8

'•7

!8-5

12

28

M

6

20 '9

1-6

22-5

6

29

81

6

19-7

''7

21-4

6

November 4

T

3

19-1

°t

5

NI

2

M'4

—

of

23

yi

8

3o-2

i-5

3i-7

12

26

n

6

26-5

1-7

28-2

12

27

XI

12

32-1

i'7

33-8

12

28

NI

6

3o-5

1-8

32-3

JO

Limb indistinct.

19

NI

6

26-8

2'0

28-8

10

December i

NI

6

28-1

2'0

3o-i

9

2

NI

6

29-6

i • 9

3i-5

8

4

NI

4

Ji-4

i • 9

33-3

8

22

I

6

23-8

1-6

25-4

6*

24

NI

6

29-3

''7

3i-o

6*

26

NI

6

32-5 1-9

34'4

5*

29

3o

NI
NI

6
6

29 '9 2'o
3o-2 i '9

3,-9

32-1

9
9

3i

n

6

26-2

1-8

aSro

8

January i

NI

6

269

1-8

28-7

8

20

NI

6

22-3

''7

24-0

0

Defective limb.

21

T

6

28-7

i'7

3o'4

ii

22
23

T
NI

6

6

33-i

34-3

1-9
1-9

35-o
36-2

n

5* ,

*4

NI

6

38-7

1-9

40-6

5*

25

NI

6

35-i

i 9

37'o

5*

27

NI

6

10. 3i. 33-i

1-8

34-9

5*

Mean, with weights, of corrected Longitudes

* On these days the corrections to
t Corrections wholly unknown.

l
by }) 2 L i

111 K

D. 3i. 29' i («ee page 27).
t satisfactory.

the Moon's Tabular Place are no

194

TRANSIT OF VENUS, 1874. HONOLULU — KAILUA.

CHRONOMETRIC CONNECTIONS.

TABLE XII. — COMPARISON of PORTABLE CHRONOMETERS with the TRANSIT-CLOCKS, and INFERRED ERROR
of the PORTABLE CHRONOMETERS on Mean Time of Place.

Station and
Approximate Local
Mean Time (Civil
Reckoning).

Time by the
Transit-Clock.

Adopted
Correction to
the Transit-
Clock.

Name of
Portable-
Chrono-
meter
compared.

Corresponding
Time by Portable-
Chronometer.

Inferred Portable-
Chronometer Slow on
Mean Time of Place.

h m s

„

h m s

h m ,

HONOLULU,

2.33. 8-0

+ 9-36

W

7- 7- o-o

+ 2. 26. 31-48

Dec. 5,

2.40. 53 -o

9-36

V

7. 1.36-5

2. 39. 38-7i

9h. 41"'. p.m.

2. 43. 32-O

+ 9'36

M

9. 40. 3 1 -o

+ o. 3. 22-77

KAILUA,

19. 37. io'o

+ 30-29

Q

2. 24. 40 • 5

+ o. 6.3i-36

Dec. 7,

19.44. SS'o

3o-3o

Q

2. 32. 24-0

o. 6. 3 1 -60

2h. 4om. p.m.

19. 42. 20 -O

3o-3o

V

11.48. 55-5

2. 47. 25-52

19. 57. 17-0

3o-3i

V

o. 3. 5o-o

2.47. 25-59

19.48. 24-0

3o-3o

W

o. 8. 1 1 • 5

2.34. 12-53

19. Si. 55-0

+ 3o-3i

W

O. 1 1 . 42 ' O

+ 2. 34. I2-45

KAILUA,

16.45. 5o-o

+ 33-44

Q

ii. 26. o- 5

+ o. 6. 30-73

Dec. 9,

16.48. 55-o

33-44

Q

11.29. 5-o

o. 6. 3o'73

Noon.

16. 52. 38-o

33-45

V

8. 51.28-0

2. 47. So- 12

16. 58. 39-0

33-45

V

8. 57. 28-0

2. 47. So- 14

1 6. 5o. 1 5-o

33-44

W

9. 2.25-5

2. 34. 3o'oi

16. 56. 14-0

+ 33-45

W

9. 8.23-5

+ 2. 34. 30-04

HONOLULU,

18. 20. o-o

+ 11-07

R

i. 1.58-0

+ o. o. 8-40

Dee^ 10,

18. 21. i5-o

11-07

V

IO. 22. 42-0

2. 40. 39-19

ih. 3™. p.m.

18. 28. 10-0

+ i i '07

W

10.43. o-o

+ 2. 27. 1 5 -06

HONOLULU,

i5. 5i.36-o

+ 12-08

u

19. O.43-5

+ 3. 17.40-53

Dec. 14,

16. 2.33-0

12-08

V

19.47. 5i-5

2.41.27-74

ioh. 3o™. a.m.

16. 2.25-0

12-08

V

19. 47- 4^ '5

2.41.27-76

i5. 55. 52-o

12-08

W

19. 54. 48-5

, 2. 27. 50-84

i5. 55.42-0

+ 12-08

W

19. 54. 38-5

+ 2. 27. 5o-87

KAILCA,

20. 25. 2O -O

+ 46-44

u

II. 22. 48- 5

+ 3. 25. 14-27

Dec. 1 5,

20. 20. 26-0

46-43

V

1 1 . 54. 2'0

2.49. 7-57

2h. 45'". p.m.

20. 17. 45-0

+ 46'43

W

o. 5. 2-5

+ 2. 35. 26-5i

KAILUA,

1 8. 9.40-0

+ 5o-25

u

8.59.26-5

+ 3.25. 3o-45

Dec. 17,

18. 12. 7-0

So -26

V

9. 37. 52-o

2.49. 3i-57

oh. 27m. p.m.

18. 5. 4-0

+ 5o-25

W

9. 44. 38-o

+ 2. 35.43-71

TABLE XII. — ERRORS OP PORTABLE-CHRONOMETERS (continued).

195

Station and
Approximate Local
Mean Time (Civil
Reckoning).

Time by the
Transit-Clock.

Adopted
Correction to
the Transit-
Clock.

Name of
Portable-
Chrono-
meter
compared.

Corresponding
Time by Portable-
Chronometer.

Inferred Portable-
Chronometer Slow 011
Mean Time of Place.

h m a

8

h m s

h » .

HONOLULU,

18. o. 5-o

+ i3-39

U

8.52. 35-5

+ 3. 18. 14-14

Dec. 1 8,

18. 3. 8-0

i3-39

U

8.55. 38-o

3. 18. 14- 14

oh. 2om. p.m.

18. 7. 5-o

i3-39

V

9. 35. 29-0

2.42. 19-49

18. 10. lo'o

13-39

V

9.38.33-5

2. 42. 19*48

18. i3.25-o

i3-39

w

9.55.39-5

2. 28.27-95

18. i6.25-o

-t- i3-39

w

9.58. 39-0

+ 2.28.27-96

HONOLULU,

1 8. 8.40-0

+ i3-79

U

8. 57. 4-0

+ 3.I8.23-72

Dec. 19,

18. 11.41-0

13-79

U

9. o. 4-5

3. 18. 23 -72

oh. 20'". p.m.

18. 18. 5-o

i3-8o

V

9. 42. 19-0

2. 42. 32' 19

18.21. 5-o

i3-8o

V

9.45. i8-5

2. 42. 32 -2O

18. 27. 3i-o

i3-8o

w

10. 5.38-5

2. 28. 37- 14

18. 3o. 3o-o

+• i3-8o

w

10. 8. 37-0

+ 2. 28.37'lS

WAIMEA,*

22. 25. 9-0

- 7- 6-97

A A

4. 27. 20 -o

— o. 7. 21-94

Dec. 20,

22. 3 1. 54-0

7. 6-96

U

i. i5. 23-o

+ 3. ii. 18-96

4h. 3o"'. p.m.

22. 37.35-0

7. 6-95

V

i. 56. So-o

2. 35. 32-04

22.43. 38-o

- 7- 6-95

w

2. 1 6. So-o

+ 2. 21. 34'o5

HONOLULU,

2O. 25. IO' O

•+• o. 14-99

U

n. 5. 4-5

+ 3. 18. 40-24

Dec. 21,

20. 26. 43 *o

o. 14-99

V

11.42. 21-0

2. 42. 56*49

2h. 25'". p.m.

20. 3o. 3 1 -o

+ o. 14-99

w

o. o. 9 • o

4 2.28.S5-87

HONOLULU,

18. 23. 2-0

+ o. 1 5 • So

U

8. $9. i3-o

+ 3.18.48-33

Dec. 22,

1 8. 26. o-o

o. 1 5 • So

tr

9. 2. lo-S

3.18.48-35

oh. 25m. p.m.

18.28. 23-o

o. 1 5 • So

V

9.40. 14-5

2.43. 6-97

18. 3i. 24-0

o. iS'Si

V

9. 43. 1 5-o

2.43. 6-97

18. 35. 9-0

o.iS-Si

w

10. I. 2-5

2.29. 3-86

18. 38. 7-0

+ o. iS-Si

w

I O. 4. 0 ' O

+ 2.29. 3-88

WAIMEA,*

21. 3. 5o-o

— 7. 2- So

u

ii. 35. 25-5

+ 3.11.43-60

Dec. 23,

21. 6. 5o-o

7- *-49

u

n. 38. 25-o

3. 11.43-62

2h. 55°'. p.m.

21. 12. l5'O

7- 2-49

V

12. 19. 26-0

2.36. 6-73

21. 20. 26-0

- 7. 2-48

w

12. 41. 42-0

+ 2. 22. O ' 40

HONOLULU,

21. O. 17-0

+ o. 1 7 • 1 1

u

ii. 27. 55-o

+ 3. 19. 5-36

Dec. 24,

21. 6. 21 "O

o. 1 7 • ii

V

o. 9. Si -5

2.43. 31-87

2h. 53'". p.m.

21. II. l5'0

+ o. 17- ii

w

o. 28. 34-0

+ 2. 29. 22-57

The adopted errors of the Sidereal Chronometer at Waimea are such as make that chronometer represent the mean of

the three in regard to carrying on time.

c c

196

TRANSIT OF VENUS, 1874. HONOLULU— KAILU A — WAIMEA.

Station and
Approximate Local
Mean Time (Civil
Reckoning).

Time by the
Transit-Clock.

Adopted
Correction to
the Transit-
Clock.

Name of
Portable-
Chrono-
meter
compared.

Corresponding
Time by Portable-
Chronometer.

Inferred Portable-
Chronometer Slow on
Mean Time of Place.

h m s

h m >:

Ii m a

HONOLULU,

21. 3i. 37-0

+ o. 20' 36

U

IT. 34. 46-5

+ 3. 19. 56-49

Dec. 3o,

21. 35. 45-0

o. 20 '36

V

o. 14. 7-0

2. 44. 43- 32

3h. om. p.m.

21. 39. 49 'o

+ o. 2O-36

w

o. 32. 37-5

+ 2. 3o. 1 6- 1 5

HONOLULU,

18. 37. 5i-o

+ c.21'53

U

8. 29. 18-0

+ 3.20.20-88

1875, Jan. -i,

1 8. 40. 5 1 'o

o. 21-53

V

9. 7.21-0

2.45. 17-38

nh. 54". a.m.

18.43. Si-o

o. 21-54

V

9. 10. 2o'5

2. 45. 17-40

1 8. 46. 27-0

+ O. 21 • 54

w

9. 27. 3i'o

+ 2. 3o. 42-48

KAILUA,

19. 5g. 5-o

+ o. 20-68

U

9. 38. 5o-o

+ 3. 27. 54- o3

Jan. 3,

20. 3. 27 -o

o. 20-68

V

10. 1 8. ii -5

(2.52.53-Si)

ih. 14™. p.m.

20. 6. 28-0

o. 20-68

V

IO. 21. II -O

2. 52. 54-82

20. 9. 43-0

+ o. 20-68

w

10. 39. 3-5

+ 2. 38. 16-79

KAILUA,

i. 56.25-0

+ o. 2 3 • oo

U

3. 3i. 7-5

+ 3.28. 4-39

Jan. 4,

2. O. 19*0

O. 23'CI

V

4. 9.55-5

2.53. 9-76

7h. Sm. p.m.

2. 3,26'0

O. 23-01

V

4. 1 3. 2-0

2.53. 9-75

1. 7.42-0

+ 0.23-02

w

4. 3i. 58-5

+ 2.38.28-56

HONOLULU,

19. 3o. 55-o

+ 0.24-58

U

9. 5.59-5

+ 3. 20. 54-07

Jan. 6,

19. 34. 12-0

o. 24- 58

V

9.44. 5-5

2.46. 4-53

ob. 3o™. p.m.

19. 38. 37-0

o. 24-58

w

10. 3. i5-c

2. 3l. I9'3l

19. 41. 3i -o

+ o. 24-58

w

10. 6. 8-5

+ 2. 3i. 19-33

HONOLULU,

22.25. 2-0

+ 0.27-61

U

11.47. 25-5

+ 3.21.21-84

Jan. 9,

22. 3l. 43-0

o. 27-61

V

0.28. 5o-5

2.46. 36-75

3h. i5m. p.m.

22. 37. O'O

+ o. 27-62

w

o. 48. 56 -o

+ 2. 31.47-39

WAIMEA,*

21. 4. 6'O

- 6.26-53

U

IO. 22. 58 -O

+ 3. 14. 16-70

Jan. 10,

21. 8. 5o'o

6.26-52

V

II. 2. 23'5

2. 39. 34-23

jb ^2m p m-

21. 12. 5o'O

/

- 6.26-52

w

II. 21. 14-5

+ 2.24.42-57

WAIMEA,*

23. 19. i3-o

— 6. 25-00

U

o. 33. 40-0

+ 3.14.24-97

Jan. ii,

23. 24. 3o-o

6. 25-00

V

i. i3. 35-o

2. 39. 46- IO

3h. 53™. p.m.

23. 28. 32-0

- 6.24-99

w

i. 32.3o-5

+ 2.24.5I-95

* See uote to preceding page.

TABLE XIII. — SPECIMEN OF COMPARISON OF SHIP- AND PORTABLE-CHRONOMETERS. 197

Station and
Approximate Local Time by the

iSSSS* Transit-doek.

Adopted
Correction to
the Transit-
Clock.

Name of
Portable-
Chrono-
meter
compared.

Corresponding
Time by Portable-
Chronometer.

Inferred Portable-
Chronometer Slow on
Mean Time of Place.

h in x

m s

li in s

h in s

HONOLULU, 22,22.23-0

+ o. 3o' 1 6

U

ii. 32. 37-0

+ 3.2I.46-58

Jan. 12, 22. 28. 48-0

o. 3o- 16

V

o. i3. 37-0

2.47. 10-53

31'. o"'. p.m. 22. 3 1. 20 -o

+ o. 3o- 16

w

o. 3i. 5-o

+ 2. 32. 14-11

HONOLULU, 20. 8. u-o

+ o. 3o" 93

U

9. 14.44-0

+ 3. 21. 54-42

Jan. i3, 20. ii. 17-0

o. 3o' 94

V

9.52.23-5

2. 47. 20-42

o'1. 40'". p.m. 20. 16.46*0

+ o. 3o'94

\v

10. 12. 5o'o

+ 2. 32. 22' O2

TABLE XIII. — SPECIMEN of the COMPARISON

of the PORTABLE-CHRONOMETERS with the

SHIP-CHRONOMETERS and ADOPTED ERRORS at each STATION.

i. HONOLULU, 1874, December 5, at gh. 40™. p.m.

Name of Ship-
Chronometer.

Ship-
Chrono-
meter
Time.

Ship-Chronometer Fast on each Portable-Chronometer at the Time
specified in the Second Column.*

Adopted Ship-
Chronometer Slow on
Honolulu Mean Time.

Name of Chro-
nometer.

Fast on M.

Fast on V.

Fast on W.

h m

h in *

h in »

h

h m s

E

9.45

o. 8.25'Si

2.44.41-45

2.

3i. 34-19

-

o. 5. 2-73

E

F

9- 39

o. 3. 18-06

2. 39. 34- OO

2.

26. 27-08

+

o. o. 4-61

F

K

9. 36

11. 59. 39-21

2. 35.55-i5

2.

22. 47 • 99

o. 3.43-54

K

U

6.23

•

8.47. 3-79

ii. 23. 19-67

I I.

10. 12-53

+

3. 16. 18-99

U

2. KAILUA, 1874, December 7, at about 2h. 3om. p.m.

Name of Ship-
Chronometer.

Ship-
Chrono-
meter
Time.

Ship-Chronometer Fast of each Portable-Chronometer at the Time
specified in the Second Column.*

Adopted Ship-
Chronometer Slow on
Kailna Mean Time.

Name of Chro-
nometer.

Fast on Q.

Fast on V.

Fast on W.

h in

U in »

h

h m s

E

2.38

o. 4. 9 '89

1.45. 4-10

2.

3i.5i-i6

+

O. 2. 21 '46

E

F

2.32

u.58.52-32

2. 39.46-67

2.

26. 34-02

o. 7.34-84

F

K

2.29

n.55. 7-27

2. 36. 1-64

2.

22.48-48

o. ii. 24-04

K

U

II. I?

8. 42. 3 1 -02

11.23. 25-08

II.

IO. I2'OO

3. 24. 0-47

U

M

2.29

ii. 55. 31-40

2. 36. 25-74

2.

23. 12-98

+

o. 10. 59-80

M

* In this Table each inferred difference between a Ship- and a Portable-Chronometer has been
comparisons made before and after landing the Portable-Chronometers.

interpolated from the

cc 2

198

TRANSIT OF VENUS, 1874. HONOLULU — KAILUA — WAIMEA.

' TABLE XIV.— ABSTRACT of ERRORS of TRAVELLING CHRONOMETERS on LOCAL MEAN TIME.

HONOLULU,

KAILUA,

KAILUA,

Name of
Chronometer.

December 5, 9*. 40™. p.m.

December 7, 2h. 40"". p.m.

December 9, Noon.

Chronometer
Time.

Chronometer
Slow on Honolulu
Mean Time.

Chronometer
Time.

Chronometer
Slow on Kailua
Mean Time.

Chronometer
Time.

Chronometer
Slow on Kailua
Mean Time.

h m

h in s

h m

h m s

h m

h m s

A

B

C

D

E

9.4$

- 0. 5. 2' 73

2.38

+ o. 2.21-46

ii. 36

+ O. 2. 20-46

F

9. 39

+ o. o. 4-61

2.32

+ o. 7. 38-84

11. 3i

•f o. 7.48-84

G

H (Sid.)

K

9.36

+ o. 3.43-54

2.29

+ o. ii. 24-04

11.27

+ o. ii. 41 -3o

M

9.40

+ o. 3. 22- 77

2.29

+ o. 10. 59-80

11.27

+ O. II. l3'7O

BB

BM

A A

BB

C C

DD

EE

FF

GG

U

6.23

+ 3. 16. 18-99

11.17

+ 3.24. 0-47

8. 14

+ 3. 24. 19- 12

V

7- 2

+ 2. 39. 38-71

H.56

+ 2. 47! 25- 55

8.54

+ 2.47. 5o- 1 3

W

7- 7

+ 2. 26. 31-48

12. 10

+ 2. 34. 12-49

9- 5

+ 2. 34. 3o-o2

Name of
Chronometer.

HONOLULU,
December 10, ih. p.m.

HONOLULU,
December 14, lo1'. 2om. a.m.

KAILUA,

December i 5, between oh. 3om. and
2h. 5om. p.m.

Chronometer
Time.

Chronometer
Slow on Honolulu
Mean Time.

Chronometer
Time.

Chronometer
Slow on Honolulu
Mean Time.

Chronometer
Time.

Chronometer
Slow on Kailua
Mean Time.

h m

h m s

h »

h m s

h m

h ,„ .

A

jo. 27

- o. 3.31-75 •

0. 25

+ o. 3. 53-12

B

10. 3i

- o. 7. 55-17

2. 9

- o. 0.33-37

C

10. 3i

- 0. 8.17-55

2. II

— o. o. 56-97

D

10. 19

+ o. 4.20-10

o. 24

+ o. ii. 52- 36

E

I. IO

— o. 5. 4-32

10.28

— o. 5. 7-10

2. IO

+ o. 2. 17-29

F

i. 6

+ o. o. 3i-37

IO. 22

+ o. o. 50-48

o.33

+ o. 8.21-17

G

.

10. 23

— O. O. 21 "40

o.36

•(- o. 7. 7-49

H (Sid.)*

i5.57

(+ o. 2. i8-i5)

18. 14

(+ o. 9.44-25)

K

i. i

+ o. 4. 27-95

10. 1 8

+ o. 5. 3-56

o.36

+ o. 12. 38-3i

M

i. i

+ o. 3. 58-55

10. 19

+ o. 4.24-98

o. 38

+ o. ii. 58-o8

BB

8.52

+ i. 30.48-68

11.17

+ i. 38. 11-79

* In this Table the Errors and Bates of Chronometer H are on Local Sidereal Time.

TABLE XIV. — ABSTRACT OF ERRORS OF TRAVELLING CHRONOMETERS (continued). 199

Name of
Chronometer.

HONOLULU,
December jo, Jb. p.m.

HONOLULU,
December 14, ioh. 20'". a.m.

KAILUA,

December i5, between oh. 3om. and
zh. 5o'". p.m.

Chronometer
Time.

Chronometer
Slow on Honolulu
Mean Time.

Chronometer
Time.

Chronometer
Slow on Honolulu
Mean Time.

Chronometer
Time.

Chronometer
Slow on Kailua
Mean Time.

h »i

h „> s

h m

h m s

h m

h m s

R M

I. IO

- 2.47. 3-08

3. 3z

- 2. 39. 56- 5o

A A

10. 23

+ 0. 0. 1-33

o.57

+ o. 7.24-06

B B

8.34

+ 1.48.38-41

II. IO

+ 1.56. 7-82

CC

10. 23

+ o. o. 3-83

i. i

+ o. 7.29-29

D D

10. z3

— o. o. 28-49

i. 3

• + o. 6. 56-88

E E

10.23

+ o. o. 5-77

i. 4

+ o. 7. 31-98

FF

10. 23

+ o. o. Z4'96

i. 5

+ °- 7-49'99

G G

10. 23

4 o. o. iz-Si

»• 7

+ o. 7.46-46

U

9.48

+ 3. 17. 4-26

7- I

+ 3. 17.40-53

11.23

-i- 3. 25. 14-27

V

to. 23

+ 2.40. 39-19

7.48

+ 2.41.27-75

11.54

+ z-49- 7" 57

w

10.43

+ 2. 27. i5'o6

7.55

+ 2.27.50-85

o. 5

+ 2.35.26-5i

KAILUA,

HONOLULU,

HONOLULU,

Name of
Chronometer.

December 17, near noon.

December 18, about nh. a.m.

December 19, about 2h. p.m.

Chronometer
Time.

Chronometer
Slow on Kailua
Mean Time.

Chronometer
Time.

Chronometer
Slow on Honolulu
Mean Time.

Chronometer
Time.

Chronometer
Slow on Honolulu
Mean Time.

h m

h m s

h m

h in i

h . m

h m s

A

II. 54

+ o. 3. 54' 17

10. 36

— o. 3.29-63

i.57

—.0. 3.28-76

B

O. O

— o. o. 38-96

10.44

— o. 8. 6-14

2. 5

- o. ?. 9-13

C

o. 4

- o. i. 4-14

10. 46

- o. 8. 3z-5i

2. 6

- o 8. 36-38

D

H.53

+ o. iz. 6-75

io.36

+ o. 4.48-86

1.56

+ o. 4. 58-24

E

o. 5

+ 0. Z. l6'32

10.48

- o. 5. 9-08

2. 7

— o. 5. 9-59

F

o. 7

+ o. 3.3i-5i

10-44

+ o. i. 12-43

2. I

+ o. i. i8-63

G

o. 4

+ o. 7. 14-84

10.47

— o. o. 5-70

2. 5

— o. o. 0-98

H (Sid.)

.7. 5i

(+o. 9.46-54)

16. 36

(+ O. 2. 22- 6l)

19.57

( + O. 2 24-46)

K

o. 4

4- o. iz. 56-55

10. 46

+ o. 5.41-13

2. 2

+ o. 5. 5i-_53

M

o. 7

+ o. 12. i3-o3

10.49

+ o. 4. 56 -3o

2. 5

+ o. 5. 5-17

RB

10. 46

+ i. 38. 9-47

9.27

+ 1.30.42-66

0.43

+ i. 30.41-97

R M

3. i

— 2. 40. 28-90

1.44

— 2.48. 9-00

5. i

- 2.48.27-18

A A

o. 3o

+ o. 7. zi-o3

n. 14

- o. o. 5-3i

2. 30

— o. o. 6-52

BB

10.43

+ i. 55. 15-42

9.27

+ 1.48. 54-09

0.43

+ 1.48.59-05

CC

o.32

+ o. 7. 3z-3o

11. 18

+ o. o. 9-30

2. 33

+ o. o. 12-04

DD

o.36

+ o. 6. 57-45

II. 21

— o. 0.26-71

2.36

— o. o. 25'6i

EE

o.37

+ o. 7. 34-17

11.23

-i- o. o. 10-54

2.'37

+ o. o. iz'32

FF

o. 38

4 o. 7. Si'gS

II. 24

+ o. 0.28-15

2. 39

+ o. o. 29-43

GG

o. 41

J- o. 8. 1-71

II. 27-

+ o. 0.44-61

2.40

4- 0. 0.53-73

U

8.59

+ 3.25.30-45

8. 54

-f 3. 18. 14-14

8.58

+ 3. 18. 23-72

V

9. 38

+ 2.49.31-57

9. 36

4 2.42. 19-49

9.42

+ 2.42. 32-19

w

9.45

4 z. 35. 43-71

9. 56

+ 2.28.27-95

10. 6

4 2. 28. 37- 14

200

TRANSIT OF VENUS, 1874. HONOLULU — KAILUA — WAIMEA.

WAIMEA,

HONOLULU,

HONOLULU,

Name of
Chronometer.

December 20, about 4"'. p.m.

December ai, about ih. p.m.

December 22, about 2h. p.m.

Chronometer
Time.

Chronometer
Slow on Waimea
Mean Time.

Chronometer
Time.

Chronometer
Slow on Honolulu
Mean Time.

Chronometer
Time.

i

Chronometer
Slow on Honolulu
Mean Time.

h m

h in s

ii in

h 111 s

h in

h ,11 s

A

2. 5

— o. 10. 42' 61

I. O

— o. 3. 29-60

1.28

- o. 3. 3o-85

B

4- 7

— o. i5. 26- 52

i- 7

- o. 8. 15-66

i.36

- o. 8. 18-86

C

4. 10

— o. 1 5. 54" 06

i. 9

- o. 8.43-53

i.39

— o. 8.47-23

D

4. o

- 0. 2. 7-94

0.58

+ o. 5. 11-71

1.27

+ o. 5. 18-76

E

4. 1 3

— o. 12. 24' 49

I. 10

— 0. 5. II '20

i. 40

- o. 5. 12-35

F

4- 9

- o. 5.48-98

i. 5

+ o. 1.29-04

i.35

+ o. i. 33-57

G

4. 12

— o. 7. 10-88

i. 8

+ o. o. 5-68

i.39

+ o. o. 8-67

H (Sid.)

22. II

(- o. 4.47-69)

19. ii

(+o. 2.27-43)

19.44

(+ o. 2. 30-90)

K

4. 12

— o. i. 12-07

i. 8

+ o. 6. 9-01

i. 38

+ o. 6. i6-55

M

4.l5

— O. 2. 0-29

I. IO

+ o. 5. 19-70

1.41

-i- o. 5.25-82

KB

2.55

+ I.23.26-59

11.48

+ i.3o.38-9i

o. 20

+ i. 3o. 37-76

RM

7- 12

- 2. 55. 58-9o

4. 6

— 2.49. 0-08

4.38

- 2-49- '7'4°

AA

4.27

- o. 7.21-94

I. 32

— o. o. 9-57

2. 7

— o. o. u -44

BB
CC

2. 52
4.43

+ 1.41.49-08
— o. 7. o-n

".44
1.35

+ 1.49. 5-8o
+ o. o. 14- 16

o. 20

2. I I

+ 1.49. 9-48

•f o. o. 14-93

DD

4.46

— o. 7. 39'i5

i- 37

— o. 0.25-40

2. 14

— 0. 0. 25-23

BE

4.48

— o. 7. 0-48

i.39

+ o. o. 13-95

2. 17

+ o. o. 14-51

FF

4. 5o

— o. 6.42-72

1.40

+ o. o. 32" 09

2. I9

+ o. o. 33-25

GG

4.53

— o. 6. 12- 3o

1.41

+ 0. I. 7'52

2. 21

+ o. i. 14-86

U

i.i5

+ 3. ii. 18-96

ii. 5

+ 3. 18. 40*24

9. o

+ 3.18.48-34

V

s '-57

+ 2.35.32-04

ii. 42

+ 2. 42. 56 -49

9.41

+ 2.43. 6-97

W

2. 17

+ 2. 21. 34'OS

o. o

+ 2.28.55-87

IO. 2

+ 2.29. 3-87

WAIMEA,

HONOLULU,

HONOLULU,

Name of
Chronometer.

December 23, about 3h. p.m.

December 24, about 3h. p.m.

December 3o, about 3h. jr.m.

Chronometer
Time.

Chronometer
Slow on Waimea
Mean Time.

Chronometer
Time.

Chronometer
Slow on Honolulu
Mean Time.

Chronometer
Time.

Chronometer
Slow on Honolulu
Mean Time.

h m

h m s

h m

h m a

h m

h 111 K

A

2.53

— o. 10. 45-85

2.24

- o. 3.23-86

2. 33

— o. 3.40-70

B

3. 0

— o. i5. 36-01

2. 3l

— o. 8.26-08

2.41

- o. 8.46-80

C

3. 4

— o. 16. 4-03

2.34

- o. 8. 53-88

2.45

— o. 9. 16-01

D

2. 52

— o. 1.47-23

2. 22

+ o. 5. 32-85

2. 3l

+ o. 6. 1 1 * 62

E

3. S

— o. 12 26-67

2. 35

- o. 5. 14-40

2.45

— O. 5.22'3o

F

3. i

- o. 5. 34-66

2. 3o

+ o. i.43-v9

2. 38

+ 0. 2. 6-g5

G

3. 5

- o. 7. 1-48

2. 33

+ o. o. 14-86

2.42

+ o. 0.27-96

H (Sid.)

21. 15

(—0. 4.40-56)

20.47

(+o. 2. 34-23)

21. 19

(+o. 2.43-51)

K

3. 4

- o. 0.47-74

2. 3l

+ o. 6.33-60

2.39

+ o. 7. 16-62

M

3. 7

— o. 1.40-38

2.34

+ o. 5. 39-61

2.42

+ o. 6. 12-71

EB

1.48

+ i. 23. 22-97

i. i3

+ i.3o.34'8o

I. 21

+ i. 3o. 27- 17

TABLE XIV. — ABSTRACT OF ERRORS OF TRAVELLING CHRONOMETERS (continued}. 201

WAIMEA,

HONOLULU,

HONOLULU,

December 23, about 3h. p.m.

December 24, about 3h. p.m.

December 3o, about 3h. p.m.

Name of

.

Chronometer.

Chronometer
Time.

Chronometer
Slow on Waimea
Mean Time.

Chronometer
Time.

Chronometer
Slow on Honolulu
Mean Time.

Chronometer
Time.

Chronometer
Slow on Honolulu
Mean Time.

h m

h m s

h in

h in s

h m

h m s

RM

6. 5

- 2. 56.48-86

5. 32

— 2.49. 52-4I

5.4I

- 2. 5i. 37-94

A A

3.24

— o. 7. 26-44

2.49

— o. o. 14-47

2. 58

— o. o. 25-78

BB

1.36

+ i. 41. 59-41

I. 2

+ i. 49. i5'8i

I. 10

+ 1.49.33-48

CC

3.28

- o. 6. 57'63

2.52

+ o. o. 16- 14

3. 3

+ o. o. 20- 1 5

D D

3. 32

- o. 7. 38-63

2.54

— O. O. 25'22

3. 6

— o. o. 27-28

K E

3.34

- o. 6. 57-98

2.55

+ o. o. 16-37

3- 7

+ o. o. i8-65

FF

3.36

- o. 6. 38-95

2.59

+ o. o. 35-72

3- 9

+ o. 0.41-90

GG

3.38

- o. 5. 5i-i5

2.59

+ o. i. 28-41

3. 9

+ 0. 2. 3-07

U

ii.37

+ 3. 11.43-61

11.28

+ 3.19. 5-36

H.35

+ 3. 19. 56-49

V

o. 19

-I- 2.36. 6-73

O. IO

+ 2.43. 31-87

o. 14

+ 2.44.43-32

w

o. 39

+ 2.22. 0-40

o. 29

+ 2.29.22-57

o. 33

+ 2. 3o. i6-65

HONOLULU,

KAILUA,

KAILUA,

1875, January 2, Noon.

January 3, about ih. p.m.

January 4, about 7h. p.m.

Name of

Chronometer.

Chronometer
Time.

Chronometer
Slow 011 Honolulu
Mean Time.

Chronometer
Time.

Chronometer
Slow on Kailua
Mean Time.

Chronometer
Time.

Chronometer
Slow on Kailua
Mean Time.

h m

h m s h m

h m s

h m

h ill K

A

ii. 53

— o. 3. 42- 16 o. 29

+ o. 3.42-09

6.38

4- o. 3.42-26

B

0. I

- o. 8. 56- 76

o.38

— o. i. 35-64

6.46

- o. I. 39-80

C

o. 4

— o. 9. 26-54

o. 42

- o. 2. 5-55

6.49

— O. 2. lO'OI

D

11.49

4- o. 6. 32-24

0.27

+ o. 14. 4- 10

6. 34

+ o. 14. 14- ii

E

o. 3

— o. 5.26-29

o. 40

+ o. i. 57-02

6.48

+ o. 1.55-89

F

11.57

+ 0. 2. 18-73

o. 34

+ 0. 9.48-36

6.42

+ o. 9. 54-61

G

o. o

+ O. O. 35'OI

o. 38

+ o. 8. 2-53

6.46

+ o. 8. 6-49

H (Sid.)

18.48

(+ o. 2.48-27)

19. 3i

( + o. 10. 14-01)

i.43

(+o. 10. i5-6;)

K

ii. 56

+ o. 7.39-27

o. 36

+ o. 1 5. 12-48

6.43

+ o. 1 5. 23-39

M

ii. 59

+ o. 6.3o-32

o. 40

+ o. 14. 2-45

6.46

+ o. 14. 11-37

KB

10. 38

+ i. 3o. 22-29

ii. 20

+ i. 37.44-30

5.26

•f 1.37.41-98

RM

3. o

- 2.52.28-58

3.4i

— 2.45.22-03

9.48

- 2.45.43-74

A A

o. 1 3

— o. o. 3o'83

0.55

+ o. 6.53-35

6.59

+ o. 6. 52-n

BB

10. 24

+ i.49-4i-95

ii. 7

+ i. 57. 9-61

5.12

+ 1.57.13-62

CC

o. i5

•f o. 0.24-37

o. 5g

+ o. 7.5o-58

7- 3

+ o. 7.53-34

DD

o. 17

— o. o. 28-93

1. 2

+ o. 6.55-57 7- 6

+ o. 6.55-86

E E

o. iS

+ o. 0.20-35

i. 3

+ o. 7-45-97 7- 7

+ o. 7-47-27

FF

o. 20

•f o. 0.45-46

i. 4

+ o. 8. 11-61 7. 10

+ o. 8. 13-77

GG

o. 20

+ O. 2. 22 "o3

i. 5

+ o. 9. 54-00

7. 10

+• o. 10. 3-45

U

8. 29

+ 3. 20. 20 '88

9- 39

+ 3.27.54-03

3. 3i

+ 3.28. 4-39

V

9- 7

+ 2.45. 17-38

10. 21

+ 2.52.54-82

4. 10

•f- 2.53. 9-76

w

9.28

+ 2. 3o. 42-48

10. 39

+ 2. 38. 16-79

4. 32

+ 2. 38.28-56

202

TRANSIT OF VENUS, 1874. HONOLULU— KAILUA — WAIMEA.

HoNOLUI.tr,

HONOLULU,

•

WAIMEA,

Name of
Chronometer.

January 6, about i1'. p.m.

January 9, about 3h. p.m.

January 10, about ih. p.m.

Chronometer
Time.

Chronometer
Slow oa Honolulu
Mean Time.

Chronometer
Time.

Chronometer
Slow on Honolulu
Mean Time.

Chronometer
Time.

Chronometer
Slow on Waimea
Mean Time.

h m

h m t

h m

h in »

h m

h m a

A

0.32

— o. 3.44-09

2.37

— o. 3.49-02

i.i5

- o. ii. 3-58

B

o. 39

— o. 9. 10- 35

2.44

— o. 9.21-96

1.24

— o. 16. 38-78

C

0.42

— o. 9. 40-69

2. 46

— o. 9. 5o-8o

1.26

— o. 17. 6-87

D

o. 26

+ o. 7. 2'i3

2. 30

+ o. 7.24-29

I. 10

+ o. o. 17-96

E

0.40

- o. 5.3i-i3

2-44

- o. 5. 35-54

1.25

— o. 12. 5o'o3

F

0. 34

+ 0. 2. 37-I6

2.37

+ o. 2.49-12

I. 20

— o. 4. 19-83

G

o.37

+ o. 0.46-66

2.40

+ o. o. 5i -5i

1.23

— o. 6. 19-73

H (Sid.)

19.41

(+ 0. 2. 52'U)

21.56

(+ o. 2.53-65)

20.43

(— o. 4. 19-04)

K

0.32

+ o. 8. 11-78

2.35

+ o. 8. 29-49

I. 19

+ o. i. 23'66

M

0.35

+ o. 6. 58 -02

2.38

+ o. 7. i3'o3

I. 22

+ o. o. 5-40

RB

ii.i5

+ I. 3o. 12-68

i. 17

+ i.3o. 6-65

o. 4

+ I. 22. 5l'o5

KM

3.37

- 2.53.39-56

5. 40

- 2. 54. 34-14

4.27

- 3. 2. 4-49

A A

0.47

— o. o. 34-48

2.49

— o. o. 39-29

i.36

- o. 7-53-53

BB

10. 59

+ 1.49.53-60

I. 0

+ i. 5o. 1-93

11.47

+ i. 42. 5 1 -72

CC

o-49

+ o. o. 3o-oo

2. 5l

+ o. o. 3i-32

i. 38

— o. 6.41-40

DD

o. Si

— o. o. 29 '36

2.53

— o. o. 31-67

1.42

— o. 7.45-64

BE

0. 52

+ o. 0.23-90

2.53

+ o. o. 24- 58

1.42

— o. 6.48-30

FF

o.53

+ o. o. 5 1 -52

2.54

+ o. 0.55-65

1.44

— o. 6. i6'23

G6

o.53

+ o. 2.49-13

2.54

+ o. 2. 58-78

1.44

— o. 4. 10-09

U

9- 6

+ 3.20.54-07

11.47

+ 3.21.21-84

10.23

+ 3. 14. 16-70

V

9-44

+ 2.46. 4-53

o. 29

+ 2.46. 36-75

II. 2

+ 2.39.34-23

w

10. 3

+ 2. 3i. 19-31

o-49

+ 2. 31.47-39

II. 21

+ 2.24.42-57

WAIMEA,

HONOLULU,

HONOLULU,

Name of
Chronometer.

January 1 1 , about 4h. p.m.

January 12, about 3h. p.m.

January i3, about i1'. p.m.

Chronometer
Time.

Chronometer
Slow on Waimea
Mean Time.

Chronometer
Time.

Chronometer
Slow on Honolulu
Mean Time.

Chronometer
Time.

Chronometer
Slow on Honolulu
Mean Time.

h m

h m .1

h m

h m 8

h m

h m s

A

3.46

— o. ii. 5-59

2. 40

- 0. 3. 53-26

o. 40

— o. 3. 54-70

B

3.54

— o. 16.43- 17

2.48

— o. 9. 32-78

0.48

- o. 9. 35-88

C

3.56

— o. 17. ii -xo

2.49

— o. 10. 0-78

0-49

— o. 10. 4-25

D

3.40

+ o. 0.26-05

2. 33

+ o. 7.46-71

o. 48

+ o. 7. 53-67

E

3.56

— o. 12. 5i -99

2.48

— o. 5. 39-70

0.49

— o. 5.41-09

F

. 3.49

- o. 4. iS'77

2.41

+ o. 3. 2-10

0.41

+ o. 3. 5-70

G

3. 53

— o. 6. 18-20

2.45

+ o. o. 57-42

0.44

+ o. 0.58-96

H (Sid.)

23.18

(— o. 4. ig-So)

22. 13

(+o. 2.54-48)

20. 1 6

(+ o. 2.53-98)

K

3.49

+ 0. I. 32-12

2.40

+ o. 8. 53-5o

o. 39

+ o. 9. 1-61

M

3.53

+ o. o. 10-89

2.43

+ o. 7. 3o-47

0.42

+ o. 7. 35- 5o

RB

2.33

+ 1.22.48-50

1.24

+ 1.29.59-85

II. 22

+ 1.29.57-91

TABLE XV. — RATES OF CHRONOMETERS AND INFERRED DIFFERENCES OF LONGITUDE. 203

TABLE XIV. (concluded).

WAIMEA,

HONOLULU,

HONOLULU,

Name of
Chronometer.

January n, about 4h. p.m.

January 12, about 3h. p.m.

January i3, about ib. p.m.

Chronometer
Time.

Chronometer
Slow on Waimea
Mean Time.

Chronometer
Time.

Chronometer
Slow on Honolulu
Mean Time.

Chronometer
Time.

Chronometer
Slow on Honolulu
Mean Time.

b iii

h m »

h

h m •

h m

h m a

KM

6.57

— 3. 2. 24' 66

5.48

— 2. 55. 28-07

3.47

— 2. 55. 44-62

AA

4. 6

— o. 7. 56'iz

2.57

— o. 0.43-67

0.55

— o. 0.45-00

BB

2. I?

+ 1.42.54-36

i. 8

+ i. 5o. io-65

n. 5

+ i. 5o. 12-93

CC

4. 8

— o. 6.41-28

3. o

+ o. 0.32-86

o. 56

+ o. 0.32-89

DD

4- "

- o. 7. 46- 74

3. 4

— o. o. 33-6o

o. 59

— o. o. 34-14

EE

4. 12

- o. 6.48-37

3. 5

+ o. 0.25-79

I. 0

+ o. 0.25-99

FF

4- H

— o. 6. 1 5*27

3. 4

+ o. o. 59-88

I. I

+ O. I. I 'O8

GG

4. i3

— o. 4. 5-70

3. 5

+ o. 3. 12- 14

I. 0

+ o. 3. 16-11

U

o. 34

+ 3.14.24-97

ii. 33

+ 3.21.46-58

9.i5

+ 3. 21. 54-42

V

i. 14

+ 2. 39. 46' IO

o. 14

+ 2.47. 10-53

9.52

+ 2.47.20-42

W

i. 33

+ 2. 24. Si'gS

o. 3i

+ 2. 32. 14-11

10. 1 3

+ 2. 32. 22-O2

TABLE XV. — STATIONARY and TRAVELLING RATES of CHRONOMETERS and INFERRED DIFFERENCES

of LONGITUDE.

Name
of
Chrono-
meter.

Stationary
Hate at
Kailua,
Dec. 7^-9.

Travelling
Rate,
Dec. 5-io.

Apparent
Difference of
Longitude.
Kailua, East of
Honolulu.

Stationary
Rate at
Honolulu,
Dec. 10-14.

Stationary
Rate at
Honolulu,
Dec. 8-1 3.

Stationary
Rate at
Kailua,
Dec. 1 5-i 7.

Travelling
Rate,
Dec. 14-18.

Apparent
Difference of
Longitude.
Kailua, East
of Honolulu.

•

s

m B

a

K

a

a

m a

A

+ O'2I

+ o-53

+ o-53

7.24-30

B

- 3-6i

- 2'93

- 2-58

7.24-77

C

•

- 3-83

- 3-75 '

- 3-7i

7.24-86

D

+ 6-90

+ 7-26

+ 7-06

7.24-59

E

- o-53

— O'2I

7.24-55

- 0-71

— o-5o

— 0-48

7.24-94

F

+ 5-34

+ 6-o5

7.23-91

+ 4-93

+ 5-23

+ 5-73

7.24-44

G

+ 2-86

+ 3-73

+ 4- 10

7.24-40

H (Sid.)

+ 1-18

+ i-iS

+ i -06

7.24-94

K

+ 9 '20

+ 9-81

7.23-79

+ 9' 16

+ 9-22

+ 9-48

7.24-36

M

+ 7-40

+ 7'9'

7.23-58

+ 6-80

+ 7-35

+ 8-o3

7.24-20

RB

- i'«7

- 1-80 '

7.25-09

RM

-16-38

-16-39

7.24-59

A A

- 1-52

- i-75

7.24-67

D D

204

TRANSIT OF VENUS, 1874. HONOLULU — KAILUA— WAIMEA.

Name
of
Chrono-
meter.

Stationary
Rate at

Kailua.
Dec. 7-9.

Travelling
Rate,
Dec. 5-io.

Apparent
Difference of
Longitude.
Kailua, East of
Honolulu.

Stationary
Rate at
Honolulu,
Dec. 10-14.

Stationary
Rate at
Honolulu,
Dec. 8-i3.

Stationary
Rate at
Kailua,
Dec. 15-17.

Travelling
Rate,
Dec. 14-18.

Apparent
Difference of
Longitude.

Kailua, East
of Honolulu.

BB

•

•

,„ s

-•

•

+ 3-84

+ 3-95

7.25-03

CC

+ i-Si

+ 1-20

7.24-13

DD

+ 0-28

+ 0-59

7.24-72

EE

+ i- 10

+ 1-26

7.24-81

FF

+ 0-99

+ o* 60

7.24-37

GG

+ 7 '70

+ 8-21

7.24-80

U

+ 9-94

+ 9-61

7.25-05

+ 9-34

+ 8-52

+ 8-00

7.24-27

V

+ i3- 10

+ 12-98

7.24-72

+ 12-49

+ 12-58

+ 12-78

7.24-88

W

+ 9-35

+ 9-34

7.25-04 •

+ 9-21

+ 9'°4

+ 9" 12

7.24-95

Name
of
Chrono-
meter.

Travelling
Rate,
Dec. 19-21.

Apparent
Difference of
Longitude.
Waimea, West
of Honolulu.

Travelling
Rate,
Dec. 22-24.

Apparent
Difference of
Longitude.
Waimea, West
of Honolulu.

Stationary
Rate at
Honolulu,
Dec. 24-30.

Stationary
Rate at
Honolulu,
Uec. 3o-,Tan. 2.

Stationary
Rate at
Kailua,
Jan. 3-4.

m s

Ill S

8

N

A

— 0-43

7.13-37

- 0-99

7.13-94

- i-3o

- o-5i

+ o- 14

B

- 3-33

7.13-78

- 3-55

7.13-39

- 3-44

- 3-45

- 3-33

C

- 3-65

7.13-72

- 3-26

7.13-35

- 3-68

- 4'°7

- 3-57

D

+ 6-68

7.13-84

+ 6-43

7.12-80

+ 6-48

+ 7-17

+ 8-00

E

- o-83

7.14-01

— I 'CO

7.13-36

- 1-32

- 1-38

— 0-90

F

+ 5-22

7.13-29

+ 4-87

7.13-39

+ 4' '4

+ 4-08

+ 5'oo

G

+ 3-40

7.13-52

+ 3-04

7.13-37

+ 2-18

+ 2-44

+ 3-i7

H (Sid.)

+ I"52

7.13-81

+ 1-66

7.13-23

+ i-55

+ 1-65

+ i-3o

K

+ 8-90

7.13-30

+ 8-35

7.13-14

+ 7'iS

+ 7-86

+ 8-68

M

+ 7-41

7.13-54

+ 6-78

7.13-39

+ 5-i8

+ 6-12

+ 7- jo

BB

- i-57

7.13-66

— 1-46

7.13-24

- i'*7

- 1-70

- 1-86

RM

-16-76

7.13-44

-I7'3i

7.13-10

-17-56

-17-53

-17-27

A A

- i-54

7.13-72

- 1-49

7.13-43

- 1-97

- i-75

— I 'CO

BB

+ 3-46

7.13-74

+ 3-12

7.13-36

+ 2-94

+ 2-93

+ 3-i8

CC

+ 1-89

7.14-11

+ 0-59

7.13-18

+ 0-66

+ i'47

+ 2-21

DD

+ o-ii

7.13-66

O'OO

7.13-40

— 0-34

- o-57

+ 0-24

EE

+ o-83

7.13-71

+ 0-92

7.13-46

+ o-38

+ 0-59

+ 1-04

FF

+ i-37

7.13-64

+ 0-72

7.12-96

+ i-o3

+ 2-39

+ I-73

GG

+ 7'°4

7.13-72

+ 6-69

7.13-05

+ 5-77

+ 6-57

+ 7-56

U

+ 7-92

7.14-14

+ 8-09

7.13-70

+ 8-52

+ 8-41

+ 8-26

V

+ 11-69

7.13-90

+ H-85

7.13-39

+ 11-90

+ 11-94

+ 11-92

W

+ 9-00

7.13-66

+ 8-90

7.13-34

+ 8-93

+ 9-17

+ 9-4*

,i

TABLE XV. — RATES OF CHRONOMETERS AND INFERRED DIFFERENCES OF

LONGITUDE (concluded).

205

Name
of
Chrono-
meter.

Travelling
Rate,
Jan. 2-6.

Apparent
Difference of
Longitude.
Kailua, East of
Honolulu.

Stationary
Rate at
Honolulu,
Jan. 6-9.

Average
Rate,
Jan. 9—12.

Apparent
Difference of
Longitude by the
Comparisons
at Waimea,
Jan. 10.

Apparent
Difference of
Longitude by the
Comparisons
at Waimea,
Jan. ii.

Stationary-
Rate at
Honolulu,
Jan. 1 2-1 3.

K

m s

a

A

— 0-76

7.25-03

- i-73

- 1-41

7. 13-25*

7.13-70*

- i-57

15

- 3-41

7.24-62

- 3-76

- 3-6o

7.13-42

7.13-83

- 3-38

C

- 3-5o

7.24-58 - 3-29

- 3-32

7.12-93

7.13-59

- 3-79

D

+ T'9

7.24-49 + 7-18

+ 7H8

7.13-40

7.13-57

+ 7-58

E

F

- i-33
+ 4'35

7.24-67 - 1-42
7.25-17 + 3-88

- i -39
+ 4-32

7.13-19
7.13-03

7.13-62
7.13-74

- i-53
+ 3-93

G

+ 2-77

7.24-68 + 1-62

+ i-83

7.12-97

7.13-46

+ 1-68

H (Sid.)

+ 0-79

7.24-92

+ o-5i

+ 0-28

7.12-96

7.13-72

— 0-54

K

+ 7-80

7. 25-19

+ 5-75

+ 8-00

7.13-41

7.13-80

+ 8-85

M

+ 6-72

7.25-22

+ 4-87

+ 5-8i

7.13-14

7.14-08

+ 5-48

n B

— 2 '64

7.24-73

- 1-96

- 2-26

7.13-45

7.13-53

— 2-II

i; M

-17-83

7.24-90

-17-67

-17-94

7.13-31 7.13-67

-i8-o5

A A

- 0-87

7.25-03 - 1-40

- i -45

7.12-86

7.13-85

- i -45

B B

+ 2-77

7.24-81

+ 2-70

+ 2-90

7.12-96

7.13-52

+ 2-48

CC

+ i '04

7.25-14

+ 0-43

+ o-5o

7.13-20

7.13-63

+ o-o3

D D

— O-26

7.24-77

- o-75

— 0-64

7.13-36

7.13-76

- o-58

K E

+ 0-81

7.24-79

+ O'22

+ 0-40

7.13-26

7.13-77

+ O'2Z

FF

+ i-4[

7.24-70

+ 1-34

+ 1-40

7.13-28 7.13-87

+ J-3i

GG

+ 6-39

7.25-38

+ 3-i3

+ 4-43

7.13-30 7.13-50

+ 4' 34

U

+ 8'2I

7.24-54

+ 8-92

+ 8-28

7.12-93

7.13-70

+ 8-65

V

+ 11-57

7.25-28

+ 10-35

+ ii -3o

7.13-14

7.13-61

+ 10-97

w

+ 9-01

7.24-84

+ 9-01

+ 8'94

7.13-20

7.13-58

+ 8-75

* Waimea, January 10 and n. The meun has been used as a single determination.

D D2

206

TRANSIT OF VENUS, 1874. HONOLULU.

TABLE XVI. — SPECIMEN of the REFLECTING CIRCLE OBSERVATIONS of the SUN at HONOLULU,

1876, March g, and INFERRED ERROR of CHRONOMETER N.

Approximate
Local Mean
Time, Civil
Reckoning.

Time by
Sidereal
Chronometer N.

t-
1 §

MO2

>1

ja

Circle Backwards
or Fonvards.

Mean Circle
Reading.

For Mean of Times.

True -Altitude
of the Center.

Chronometer N
Slow on
Local Mean
Time.

N. P. D. of

the Sun
and Equation
of Time.

Refraction.
Semidiameter.
Parallax.

1875.

h m a

0 fit

° / //

h i» s

March 9,

8h. I5m. A.M.

19.22. 4-2
19.23. 3-5

u

B

54. I. 20*0

54.27.23-3

0 t II

94.25.35-5

/ //

1.46-8

26. 43. o
26. 56. 2

+ o. 52. 24-2
23-4

19. 2?. Sg-S

54. 52. 40-0

m »

1 6. I2'2

27. 8. 40

24-1

19.25. 8-5

55. 23.13-3

+ I0.42-45

8-0

27.23.57

23-7

19.26. 3'o

55.47.23-3

27. 36. 2

23-5

8h. z3m. A.M.

19. 28. 27-0
19.29. 3o-5

L

F

55. 47. io'o
56.i5. 33-3

O 1 If

94. 25.29-0

/ '/
1.42-65

28. 8. i
28.22. 1 3

+ 0. 52. 23'2

23 '7

19. 30.45-0

56. 48. 20-0

m H

l6. I2'2

28. 38. 36

23-i

19.32. 6-8

57.24.33-3

+ I0.42-38

8-0

28.56.43

23-o

19.33. 6-3

57. 50.46-7

29. 9.49

22-7

3h. 43m. P.M.

2.49.44-0

2. Si. 0'7

L

B

64. 29. 36-7
63.56.23-3

O f tl

94. 18. 19-0

/ //

1.28-6

32. 29. 5 1

32. i3. iS

+ o. Si. i3-2
12-4

2. Si. 5o-o

63.34. 33-3

m s

l6. I2'2

32. 2. 20

12-9

2.52.33-0

63.15.46-7

+ I0.37-68

8-0

3i.52. 56

iz-8

2.53.21-5

62.54.36-7

3l.42. 21

12-5

3h. 53". P.M.

2.59. 3-o

2. 59. Sg-O

U

F

61. 30.40-0
61. 5.56-7

O / //

94.18. 8-5

r /f

1.34-8

3o. 27. 3o
3o. i5. 8

+ o. Si. n-6

11-7

3. I. 19-0

60. 3o. 40-0

m s

l6. 12-2

29. 57. 3o

ii-6

3. 4. o-o

59.19.33-3

+ 10. 37-57

8-0

29.21.57

11-4

3. 6. o-o

58.26.56-7

28.55.38

IO-2

Index Correction of the Circle, + 22", Circle Backwards. Baroi
— 22", Circle Forwards. Extei

A.M.

P.M.

3o-io

77-0

nal Thermometer . . 69-5

Latitude, 21°. 17'. 58".

Assumed Longitude, ioh. 3im. 14". West.

Adopted N Slow on Local Mean Time, 1874, Dec. 9, near Noon, at 23h. 12™. 9s- 2 by itself, +oh. 5im. 47' -75.

DIFFERENCE OF LONGITUDE. HONOLULU — SAN FRANCISCO (continued).

207

TABLE XVII. — ERRORS of CHRONOMETERS at HONOLULU before sailing for SAN FRANCISCO.

Name of
Chronometer.

1875, March 7, near Noon.

March 8, near Noon.

March 9, near Noon.

Chronometer
Time.

Chronometer
Slow on Honolulu
Mean Time.

Chronometer
Time.

Chronometer
Slow on Honolulu
Mean Time.

Chronometer
Time.

Chronometer
Slow on Honolulu
Mean Time.

h m s

h tn

h m s

h m

h m <

A

o. 5g

— o. 4. 39-80

o. 3i

— o. 4. 39-86

o. 45

— o. 4. 39-26

B

i. 8

— o. i3. io-i5

o. 40

— o. 1 3. 14-02

o. 54

— o. i3. 17-41

C

'• 9

— o. 1 3. 6' oo

o. 40

— o. i3. 9-45

o. 54

— o. i3. 12-75

D

0.42

+ o. 14. 29-88

0.13

+ o. 14. 36-87

0.27

+ o. 14.44-94

E

i. 4

- o. 7. 6-65

o.35

— o. 7. 8-66

0.49

— o. 7. 9-81

F

o. 5i

+ o. 6.41-85

O. 22

+ o. 6.45-60

o.36

+ o. 6. 50-45

G

o.56

+ o. 2.42-44

o. 26

+ o. 2.44-62

o. 41

+ o. 2.47-89

L

0.44

+ o. 16. 4-45

o. 14

+ o. 16. 3-14

0.28

+ o. 16. 2-92

O

o.53

+ o. 8.40-36

0.25

+ o. 8.42-07

o.37

+ o. 8.43-94

Q

ii. 5o

+ o. i. io-63

0. O

+ o. i. 10-61

H.55

+ o. i. 11-98

R

n.36

+ o. 16. 7-93

II. 45

+ o. 1 6. 2-72

n.38

+ o. i5. 58-47

S

—

—

o. So

- o. 0.45-55

V

0.46

+ o. 16. 22-26

o. 1 8

+ o. 16. 3i-38

o. 3o

I- o. 16.41-07

w

10. 23

+ 2.40.24-66

9.54

+ 2.40.33-34

10. 6

+ 2. 40. 43 ' 24

RH

—

—

8. 3o*

+ 5.3I.I9-34

EB

—

—

0.37*

+ I.28.37-64

RM

~

5.22*

- 3. 11.24-75

h m •

h m a

h m s

-3 H

1 '

£ N

23. 3o. 3o

22. Si. 59

+ 1.28.43-89
+ o. 59.33-82

23. 5. o
23. 6. iS

+ 1.24.44-78
+ 0.55.40-21

23.23.25
23. 12. 9

+ 1.20. 39'o5

+ o. 51.47-75

* About 2h. 5"'. p.m.

h in liiushms

March 10, o. 20, Honolulu Mean Time, Chronometer H, n. 3z. 3o, + o. 47. 15-79.

„ o. 25, „ „ S, o. 26, — o. o. 46- 3i.

„ i. o, „ „ R H, 7.28, + 5. 3i. 24-65.

„ i. 6, „ „ R B, ii. 37, + i. 28. 36-20.

,. i. n, „ „ R M, 4.23, — 3.11.42-20.

March i5, 4. 22, „ „ H, 3. 54. 35, + o. 27. 0-82.

„ 4.28, „ „ S, 4.29, -o. 0.46-92.

208

TRANSIT OF VENUS, 1874. HONOLULU.

March 17, about 4 p.m.*

Name of —

Chronometer. Chronometer
Time.

Chronometer

Slow on Honolulu

Mean Time.

Murch 1 8, ahout z p.m.*

Chronometer
Time.

Chronometer

Slow on Honolulu

Mean Time.

March 20, about 9 a.m.*

Chronometer
Time.

Chronometer

Slow on Honolulu
Mean Time.

A
B
C
D
E
F
G
L
O

Q*
R*
S
V

w

R H
RB

RM

4.
4.
4.
3.
4.
3.
4-
3.

4-
o.
n.
4.
3.
1.

8
18
18
49
13
59

3
5z

o

6
5z
i3
52
28

4. i5f

- o. 4.

— o. i3.

— o. i3.
+ o. 1 5.

- o. 7.
+ o. 7.
+ o. 3.
+ o. 1 5.
+ o. 9.
+ o. i.
+ o. i5.

- o. 0.
•+• o. 17.
+ 2,41.
+ 5.32.
+ 1.28.

- 3. i3.

36-85
48-47
39-34
46-23
22-43
26-23

9-69
56-74

3'43
12-40
2o'47
47-73
55-8i
59-36

9-54
28-15
38-26

h m
1.32

1.42
1.42

i. i3
i.37
i.33
i. 27
i. 16
1.24

0. 12

ii. 58
i.37

1. 16

IO. 52

3.53f

8. 2f

o.45f

Ii in

- o. 4.

- o. i3.

- o. i 3.
+ o. i 5.

- o. 7.
+ o. 7.
+ o. 3.
+ o. 1 5.
+ o. 9.
+ o. i.
+ o. 1 5.
— o. o.
+ o. 18.
+ 2.42.
+ 5. 32.
+ 1.28.

- 3. i3.

37Mi
52-35
42-60
52-63
14-06
29-81
11-69
55-66
5-i8
12-72
1 5 '20
48-12
3-59
7-32
14-75
26-36
52-78

8.44
8. 54
8. 54
8.25
8.49
8. 34
8.39
8.28
8.37
o. o

"•47
8. 5i
8. 29
6. 5

O. 2lf

4. 29f
9-'4t

- o. 4.

- o. i3.

- o. i3.
+ o. 16.

- o. 7.
+ o. 7.
+ o. 3.
+ o. 1 5.
+ o. 9.
+ o. i.
+ o. 1 5.
— o. o.
+ o. 18.
+ 2.42.
+ 5. 32.
+ 1.28.

- 3. i3.

36-89
59-42
48 -56

6 - 24
26-93
38-o3
16-66
54-44

9-84
12-95

5-46
47-65
19-75
24-33

3i-99
23-85
32 -o5

•a H

I J
33 N*

3.48. o

3. 20. O

23.46.36

+ o. 19. 12-16

+ 0.47.35-35

+ o. 20. 49-87

i. i5.25

0.47.35

23. 55. 43

+ o. 43. 57-69
+ o. 16. 57-90

h m 5

8. 34. 3o

8. 7. o

23.47. ii

+ o. 8.40-12
+ o. 36. 39-38
+ o. 9. 1 6- 84

* The Errors of N, R, and Q correspond more nearly to Noon.

f March 17, about ih. p.m. March 18, 9^''. a.m. March 20, 6lj. p.m.

March 7 observations a.m. and p.m.

8

9

10
:5
16

'7
18

20

a.m. and p.m.

a.m. and p.m.

a.m. only. Cloudy p.m.

a.m. and p.m.

a.m. only. Cloudy p.m.

a.m. and p.m.

a.m. and p.m.

a.m. and p.m.

DIFFERENCE OF LONGITUDE. HONOLULU — SAN FRANCISCO (continued).

209

TABLE XVIII. — EKUOUS of CHRONOMETERS :it MARE ISLAND, SAN FRANCISCO, after the Voyage from

HONOLULU.

Name of
Chronometer.

1875, April 9, about 2 p.m.

April 10, about 3 p.m.

April 12, about 9 a.m.

Chronometer
Time.

Chronometer
Slow on Mare Island
Mean Time.

Chronometer
Time.

Chronometer
Slow on Mare Island
Mean Time.

Chronometer
Time.

Chronometer
Slow on Mare Island
Mean Time.

h 111

h

h m

h in s

I) 111

h in N

A

II. 32

+ 2. 17. 36-49 o. 52

+ 2. 17, 35-l6

6. i3

+ 2. 17. 33-90

B

11.43

+ 2. 6.49-49 >• 4

+ 2. 6.43-65

6.25

+ 2. 6.35-92

C

11.43

+ 2. 7. 5i- 10 i. 3

+ 2. 7.49-32

6. 24

+ 2. 7.45-78

D

II. IO

+ 2.41. 7-86 o. 3o + 2.41.16-45 5. 5i

^ i i

+ 2.4I.3I-86

E

ii.37

+ 2. I4.43-05

o. 58 + 2. 14.41-84 6. 1 8

+ 2. 14.40- 19

F

ii. 20

+ 2.31.46-77 0.41 + 2. 3i. 5o-oo

6. i

+ 2. 3i. 56-62

G

ii. 26

+ 2. 26. 22'66 O. 48

+ 2. 26. 24-06

6. 7

+ 2.26.28-28

L

ii. 16

+ 2. 37. 59-30 o. 38

+ 2.37.57-42

5.57

+ 2. 37. 55-69

O

ii. 24

+ 2. 32. 6-5i o. 47

+ 2. 32. 7-55

6. 5

+ 2. 32. IO-I7

Q

2. 0*

+ 2. 23. 53-33 9. 32f

+ 2.23.53-00

9. 39f

+ 2. 23.49-70

u

1.48*

r5.26
+ 2.35.56-82 1
I i. 14

+ 2. 35. 53-35-1
+ 2.35. 5i-2iJ

s

ii. 35

+ 2.22. 3'3l O. 58 + 2.22. 4'27

6. 16

+ 2.22. 3-77

V

ii. ii

+ 2.44.19-92 o. 32 + 2.44.30-22

5. 5i

+ 2. 44. 48 ' I O

w

8.48

+ 5. 7. 51-49

10. 9 4- 5. 8. o-55

3.28

+ 5. 8. 16-24

1! H

—

6. 34

+ 7. 56. 27-09

4. 6

4- 7. 56. 29-72

RB

—

10.42

+ 3. 5o. 24-66

8. 12

+ 3. 5o. 20-25

RM

3. 3i

— o. 58. 14-91

i. i

- o. 58. 5o-5i

h in s

tl 111 R

b m *

~, H

o. 41. 20

+ I. 12. 4-77

2. 6. 5o

+ i. 7.55-62

7-33. 5

+ i. i. 9-52

% N

O. 1 6. 40

3. 9. 38*

+ I. 37. 20-78
+ I.I3.34-67

i. 42. 5o

22. 45. 42f

+ i.33. 1-98
+ i. 10. 24-07

7. 8. 5o

+ 1.26. 1-77

4- I. 2.37-72

April 9. Observations p.m. only. Cloudy morning.

April 10. Observations a.m. and p.m. The errors of It correspond respectively.
April 12. Observations a.m. and p.m. H was found to have run down.

April 1 5. < )bservations a.m. and p.m.

* About 4h. 20m. p.m. •(• Near noon.

210

TRANSIT OF VENUS. HONOLULU (concluded).

TABLE XIX. — RATES of CHRONOMETERS and INFERRED

TABLE XVIII. (concluded).

DIFFERENCE of LONGITUDE between MARE ISLAND

and HONOLULU.

April 1 5, about 9 a.m.

Average

Average

Concluded

Name of

Rate at

Rate at

Adopted

Difference of

Chronometer.

Chronometer
Time.

Chronometer
Slow on Mare Island

Honolulu,
March 7 to

Mare Island,
April 9 to

Travelling
Kate.

Longitude.
Mare Island, East

Mean Time.

March 20.

April 1 5.

of Honolulu.*

h m

h

s

s

h in s

A

6. 7

+ 2. I/. 27-62

+ 0-260

— 1-421

- o-58o

2. 22. 25-49

B

6. 19

+ 2. 6.21-83

- 3-829

- 4"679

- 4-254

I3-96

C

6. 18

+ 2. 7.39-63

- 3-3oi

- 2-018

— 2-660

32-78

D

5.44

+ 2.4I.56-93

+ 7-539

+ 8-623

+ 8-081

18-19

E

6. 12

•f 2. 14. 37-I9

- i-56o

- 0-994

- 1-277

35-19

F

5.55

+ 2. 32. 7'l8

+ 4-394

+ 3-633

+ 4-013

47-99

G

6. i

+ 2. 26. 32-96

+ 2-681

+ 1-967

+ 2-324

I9'05

L

5. Si

+ 2.37.5I-75

- 0-764

— • I'2JI

- 0-987

24-47

O

5. 58

+ 2. 32. I6-34

+ z-326

-t- I ' 780

+ 2-o53

l5'24

Q

9.45f

+ 2.a3.4I-6o

+ o-i57

- I'9?5

— 0-909

(60-68)

B

—

- 4-770

- 5-740

- 5-255

37-2I

S

6. 9

+ 2. 22. 2'49

— 0-224

— o-23o

— 0-227

(56-85)

V

5.44

+ 2.45. 17-72

+ 9">o5

+ I o • 1 09

+ 9-657

44-87

w

3.21

+ 5. 8.43-29

+ 9'35o

+ 9-024

+ 9-187

22'l3

RH

o. Jg

+ 7. 56. 32' 16

+ 6-430

+ 0-990

+ 3-710

(41-83)

RB

4-45

+ 3. So. i3-38

- 1-225

- s-38o

- 1-802

38-79

RM

9-35

— o. 59. 44-04

— 16-740

-18-730

-i7-735

26-23

h to B

m s

H

7.38.25

+ 0.49.22-29

- 3.54-575

- 3.55-3io

- 3.54-943

24-92

J

7. 14. 3o

+ i. 1 3. 5o-3o

- 4. 2-984

- 4. 3-525

- 4. 3-255

27-84

N

23. 8. 27f

+ o. 5o. 56-98

- 3.5i-445

- 3.52-555

- 3. 52-ooo

2. 22. 11-23

h m s s

* The absolute time at Honolulu, forming the starting point of the journey, is the mean of all the observations on
March 17, 18, and 20 (about March 18, 9h). The absolute time at Mare Island, forming the end of the journey, is
the mean of the observations on April 9 and 10 (about April 9, 19"). The travelling rate is therefore applied to an

interval of 22 days 8 hours, approximately.

f Near noon.

TRANSIT OF VENUS, 1874.
PART I.

EXPEDITION TO THE HAWAIIAN ISLANDS

(continued).

Section 2.
OBSERVATIONS AT KAILUA,

By PROFESSOR G. FORBES, F.R.S.E.

E E

212

CONTENTS.

PAGE

Establishment at Kailua -- - --213

The Transit Clock ..... - „

The Transit Instrument ... „

Equatorial Intervals of the Wires ...-.- 214
The Level Error - „

Error of Collimation - -- - 215

Azimuth Error --------„

The Meridian Mark - - - - - - - „

Transits observed at Kailua - - - - - -216

Errors and Bates of the Transit Clock - - 217

Longitude of Kailua - - - - - - - -218

Latitude of Kailua - - 219

Professor G-. Forbes' Report of his Observations during the Ingress of Venus,

1874, December 8 „

Equations resulting therefrom ...... 224

Observations in Tabular Arrangement : —

Table I. — Transit Instrument Level Error- - - - 225

II.— „ „ Azimuth Error - 227

III. — Observations of the Meridian Mark .... 229

IV. — Transits of Stars and of the Mooii - - 230

V.— Adopted Errors and Rates of the Transit Clock - - 234

Plate VI.— Plan of Kailua - - - - - to face 213

ilah.-Vi.

Tran.<xt of Verws J874 Dec. 8.

Plan of tfie Station at KcdJua,, Island of Hawaii.

Very

\

Scale of' English, Feel.

too o 100 too joo 400 sno eoo

Reference A,1he. transit instrument.
Q.lhf Eqwatarial.
B, C, D,E, theodolite stations.

o ST Coymr

TRANSIT OF VENUS, 1874. KAILUA. 213

OBSERVATIONS AT KAILUA, ISLAND OF HAWAII.
By PROFESSOR GEORGE FORBES, F.K.S.E.

HAVING selected KAILUA as his place of observation, Professor FORBES arrived
there in H.M.S. Scout, Captain R. P. CATOR, R.N., from Honolulu, 1874,
November 5. A commodious dwelling had been most kindly placed at his
disposal by H.R.H. the Princess RUTH, who occasionally resided there herself,
the grounds of which offered a suitable position for the instruments ; and
these were, for the most part, ready for use by November 15. The position
of the observatories is shown in Plate VI. ; the transit pier was 200 feet S.W.
of the most southern corner of the stone church.

Professor Forbes undertook continuous observations for local time, and to
obtain as many meridional transits of the Moon as possible during his stay.
The Longitude of his station, however, was to depend upon the fundamental
determination of the longitude of the station at Honolulu, with which it was
to be connected by transportation of chronometers.

The Transit Clock was originally constructed by Earnshaw, for the Royal
Observatory, Greenwich, many years ago. Its former gridiron pendulum
was replaced by one of Messrs. E. Dent and Co.'s cylindrical zinc and steel
pendulums, and it was otherwise put into good order by them. At Kailua
it was mounted on a firm tripod pedestal of wood and iron, which stood upon
pickets of 8-inch timber driven firmly into the ground, the floor of the
observatory being cut away clear of them.

Professor Forbes was supplied with a fine transit instrument by Messrs.
T. Cooke and Sons, which was kindly lent to the Astronomer Royal by
WILLIAM GARNETT, Esq., of Bashall Lodge, Clitheroe.

The Transit Instrument, from its size and weight, could hardly be termed
a " portable " instrument. The object-glass was 2f inches aperture and
about 36 inches focal length. The axis was 21 inches long and of great
strength. The stand was of cast iron, unusually massive, and, at Kailua,
stood upon a brick pier, with firm foundations on solid rock. The com-
modious wooden observatory, 13 feet by 10, was built at Honolulu.

E E 2

214 TRANSIT OF VEXUS, 1874. KAILUA.

The eye-end of tlie telescope was furnished with a fixed system of nine
vertical wires of spider's web and the usual pair of horizontal wires. There
was no micrometer.

The Equatorial intervals of ilie, wires were found from, the whole of the
observed transits as follows, the signs being those proper for Equatorial stars

when the illuminating lamp was "West : —

i n /n

Wire a + 5.47-81 Wire/ — i. 28-18

b + 4.24-07 (j — 2.55-55

c + 2.53-34 h — 4.24-89

d + 1.27-41 k — 5.52-68
e o. o • oo

The intervals of the wires a, c, e, g, and Je depend partly upon 200 transits
of clock stars and partly upon transits of close circumpolar stars ; those of
the remaining wires upon the circumpolar stars only.

The Level Error was determined by means of a large striding level, the
bubble of which was graduated to single seconds by the makers. The
accuracy of the graduation was tested by Messrs. Troughton and Simms
before the instrument left England.

The correction to the level error on account of inequality of the pivots was

found to be —

//

On 1874, October i3, — i -oo with lamp West.
„ November 19, — °'99 „

On this latter day the correction was determined in three positions of the
telescope, corresponding to 0°, 30°, and 60°, Zenith Distance, and found to be
0" • 97, 0" • 99, and 1" • 02 respectively. The pivots were therefore sensibly
circular.

It was found that the Level Error was disturbed by the heat conducted
and radiated from the illuminating lamp. On December 3, Professor Forbes
found that when the lamp was east it lowered the east pivot 5" of arc. He
generally removed the lamp before applying the striding level. The syste-
matic discordance between the results for clock error obtained with the
reversed positions of the instrument (see page 217) is probably due to this
cause.

The Level was adjusted November 26 and December 22.

Table I. contains the determinations of the level error while the instrument
was mounted at Kailua.

MERIDIONAL OBSERVATIONS.

215

The Error of Collimation of the center wire was obtained from observations
of Polaris on side wires and of the Meridian Mark on the center wire as
follows, the sign being considered positive when it implies an additive cor-
rection to the observed time of transits of equatorial stars with the lamp
West :—

1874.

By Mer.
By Polaris. Mark.

By Polaris.

By Mcr.
Mark.

Nov. 23

+ 8-9 -'

1874. Dec. 24

4- 10-4

28

4- 9'3

25 —

4- 9'5

Dec. i

4- 8-7

26 —

4- 9''

3

+ 8-4

27 —

4- 9-1

4

4-10-3

28 —

+ 9'1

9

+ 9'8 -

29 4- 8-5

4-10- 1

1 1

4- 8-6

3o —

+ 9" i

i3

4- 6-2

3i 4-13-7

4-ii'7

17

4-g-I + 12' 1

1875. Jan. i

4- 9'i

18

4-n'o 4- 1 1 -7

2 (-15-9)

+ 9'1

19

4-n-i

3 4- 9-1

4- 9-8

20

4- 10-4 4- 1 1 'i

4

4- 9'i

2 I

4- io'2 -fii-6

12 —

4- 9'i

22

+ 8-4 -

The value 9" '72 (+ for lamp West) has been used throughout the
reductions.

The Azimuth Error depends generally upon the observation of a close
circumpolar star ; occasionally upon the Meridian Mark. This was placed
upon a small brick pier on the ridge of a slight eminence to the north, un-
fortunately, owing to the nature of the ground, only 1,229 feet from the
transit instrument. The mark itself was a copper plate perforated with a
horizontal line of circular holes, sensibly equidistant, 1 • 875 inches apart,
from center to center, every fifth hole being somewhat elongated in a vertical
direction. In the field of view of the instrument, therefore, the distance
between the holes from center to center subtended 26" • 23. The mark was
observed by daylight, and was rendered sufficiently distinct by placing a
pasteboard diaphragm before the object-glass, having a vertical slit £ of an
inch wide. The value of the intervals on the copper plate were also found
from numerous observations of the position of side wires at the times when
the center wire was usually observed. From these are obtained the following
results : —

216

TRANSIT OF VENUS, 1874. KAILUA.

Wires.

Number of Intervals
on the Copper
Plate.

Number of
Obser-
vations.

Adopted
Interval of the
Wires.

Value of one
Interval on the
Copper Plate.

From b to c

d

3-43
3-3i
3-32
3-43
3-36
3-41

6

9
'4

«4

8

7

//

9°'7
85-g
87-4
88-2
87-4
8g-3

Mea

//

26'5
26'0
26-3

25-7
26-0

26' 2

., c to d

., dtoe

., e to f. .

„ ftoa..

„ ff to h

n. . . . 26 • i

The center of the mark was 76"-6 West of true North. (Table III.).

"When making an observation of the mark, the position of the wire on the
image of the copper scale was estimated to the nearest tenth of a division ;
this was done with much greater accuracy than was to be expected.

When no close circumpolar star has been observed, the azimuth-error and
clock-correction have been deduced from all the observed transits in the
following manner : —

If x be the azimuth-error and y the clock-correction corresponding to the
mean of the times,

a = i5Sin' Stare N'P'D ' (usua^y termed the "Azimuth-factor"),
b = a quantity, in seconds of time, obtained by subtracting the star's
apparent Right Ascension from the clock time of transit corrected
for level and collimation, and, if necessary, for clock rate,
each star will give an equation of the form —

ax + y-\-b = o.

Such equations have been solved by the method of least squares to obtain
the most probable values of x and y.

In Table II. the extreme N.P.D.'s are given on each occasion of the employ-
ment of this method.

Tables II. and III. exhibit the observed and adopted Error of Azimuth,
and the observations of the mark.

The Azimuth was adjusted November 24 and 26, December 18 and 31.

TRANSITS of STARS and of the MOON observed at KAILUA.

The description at page 15 of the stars observed at Honolulu, the method
of reduction, and the arrangement of Table IV., applies to Kailua in every
particular.

MERIDIONAL OBSERVATIONS. 217

The places of Bradley 1730, 1731, 3058, and Groombridge 2053, which were
occasionally observed for Azimuth Error, have been brought up from the
Greenwich Catalogues for 1860 and 1864, and from the First Radcliffe
Catalogue. Professor Forbes always observed clock stars on the five wires
a, c, e, g, k. For complete transits the mean of the times has been reduced

to the center wire by applying the correction - . g.1 y-p-jy additive with lamp

East. Each wire of the imperfect transits has been reduced to the center
wire by means of the intervals given at page 214. When a star has been
observed on one side wire only the clock time recorded is given at the foot of
the page.

The observations of circumpolar stars, with reversed positions of the transit
axis, are separately reduced, and are occasionally very discordant ; partly in
consequence of the disturbing effect of the heat radiated from the illuminating
lamp, and partly, occasionally at least, from an apparent liability of the
Azimuth adjustment to be disturbed by the act of reversal, which was
performed by the hands.

In the case of the Moon, the clock time of true transit over the Meridian
has been corrected for the amount of the Moon's motion in R. A. correspond-
ing to the sum of the instrumental corrections.

The transits selected for publication are those observed for chronometric
connections, for the R. A. of the Moon's limb, and for the Ingress of Venus.

ERRORS and RATE of the TRANSIT-CLOCK at KAILUA.

"When the means of the " clock slow " obtained from stars observed with
lamp E. and lamp "W. are separately taken, and the one reduced to the other
by means of the rate, it is found that with lamp W. the clock is generally
more slow than with lamp E. as follows : —

» s

1874. December i 4- o'5o 1874. December 18 +0*12

3 — o-3i 21 + o-38

4 + o'25 22 + o-52

6 + o'ig 28 + o'4O

7 + 0-14 29 + o-i3
9 -j- o'56 3 1 — 0*04

ii 4- 0-14 1876. January 2 + 0*42

15 + 0-24 3 + 0-22

16 + o-3i 4 + 0-20

17 + 0-44

218

TRANSIT OF VENUS, 1874. KAILUA.

The mean of these is +0S<28 ; December 3 and 31 are correctly reduced.
On the few occasions when stars were observed with the instrument in one
position only, one half of this quantity has been applied to the mean clock
slow in Table V. The chronometric connection with Honolulu is, however,
unaffected by them. The clock correction applied to the transit of the Moon
is, of course, that proper to the position of the instrument.

MERIDIONAL TRANSITS of the MOON observed at KAILUA, and
inferred LONGITUDE.

In Table IV. are given the clock time, properly corrected, of the passage
of the Moon's limb over the true Meridian (affected, however, by diurnal
aberration) and the clock correction at that instant. The following results
have been obtained by interpolation, with fourth differences, from the section
Moon Culminating Stars in the Nautical Almanac. The corrections to the
Ephemeris are taken from the Appendix.

Observed R. A.

Correction

1874.

of the
Moon.

of the Moon's
Limb on the
Meridian.

Longitude deduced from
the Ephemeris.

to the
Ephemeris

(0-

Corrected
Longitude.

Weight.

h m

h m s s

h m s

November 2 3

II.

4.41. 34-54

'o. 23.44- 36 — 21 -i3 f

- 0-74

10. 24. o'o

24

II.

5. So. 16-52

»e>. i3. 48-92 — 20-91 t

— 0-80

10.24. 5'7

26

II.

8. 2.19-83

10. 23. ^T-32 — 23-44 e

- 0-84

10. 24. I -o

December i5

I.

z3. 25. 47' 16

10.23.50-90 — 28-40*

- o-36

10. 24. I • i

*

J7

I.

I. 8.34'So

10. 23.45-60 — 27-19 6

— 0-43

10. 23. 57-3

21

I.

5. ii. 16-63

10.23.40*91 — 21-20 e

— 0-70

io.23.55-8

22

II.

3 6/22. 3i-6S

10. 23. 37-90 — 2i-o3 e

- °'79

io.23. 54-5

I*

10. 23. 57* 5

5 II

* On December 1 5 and 22 stars were not observed at the same time as the Moon.

Professor Forbes' station was also connected with the head station at
Honolulu by transportation of chronometers. This work has been given in
sufficient detail in the preceding account of operations at Honolulu. f The
difference of longitude between the transit piers of the two stations was found
to be 7m. 24S<64. The adopted longitude of the Transit Pier at Honolulu is

Chronometric connections, p. 30, and Tables XII. to XV., Honolulu Section.'

LATITUDE OF KAILUA. FORBES' OBSERVATION OF INGRESS. 219

10h. 31m. 263-3 "West of Greenwich. Hence the longitude of the Transit Pier
at Kailua is 10h. 24m. ls<7 West of Greenwich.

LATITUDE of KAILUA.

The instrument used by Professor Forbes for the determination of the
approximate latitude of his station was a repeating reflecting circle by
Troughton and Simms, kindly lent by the Royal Astronomical Society.

Professor Forbes says : " In practice I never used this instrument as a
" repeating circle, but simply as an improved form of sextant ; the double
" verniers giving greater accuracy and elimin'ating error of centering, the
" power of moving the circle bodily being used as a means of varying the
" zero-reading. Observations were made only on the Sun about noon.
" Previous to a set of observations contacts were made with the limbs of the
" two images of the Sun in the same manner as the readings ' off the arc '
" and ' on the arc ' are made with a sextant. This gave the zero-reading
" and also a check-observation of the Sun's diameter. Eight or ten observa-
" tions of the Sun's double altitude, as reflected from mercury, were made on
" each occasion, Lieutenant Noble taking time by the Transit-Clock, or from
" a chronometer which was compared with the clock."

From these observations the latitude appears to be 19°. 38' '4 North.

REPORT of PROFESSOR GEORGE FORBES on his OBSERVATIONS of the INGRESS
of VENUS, 1874, December 8.

Operations at KAILUA, 1874, December 8.

H.M.S.\Fewed!os, Captain FRED. VAN DER MEULEN, arrived on December 7.
Comparisons were made between the Transit-Clock and some chronometers
brought for a preliminary longitude-run.

Captain VAN DER MEULEN told off some officers to take time and assist in
the observations ; Lieutenant H. C. BIGGE had been staying at Kailua some
time, and the most responsible work was allotted to him. The driving clock
of the large Equatoreal was a very imperfect arrangement. It was so
irregular in its action (after all care had been taken to make its parts work
easily) that it was necessary to have some one well fitted for the work to
accelerate or retard the motion slightly, and gently, and to re-connect the
clock-work. Mr. Bigge accomplished this admirably. He also attended to
the sunshade, clamps, &c.

F F

220

TRANSIT OF VENUS, 1874. KAILUA.

Mr. J. M. LLOYD, Navigating Lieutenant, was appointed to take time for
me. The instruments were so arranged that at the time of actual observation
it should be possible for a person stationed at the Transit- Clock to record
time for an observer at the Equatoreal.

Eight marines were told off, four at a time, under the command of a
sergeant, to keep silence during the time of observation. A native was
supplied by Mr. KAAI to act as interpreter to the marines in case of necessity.
To each of the marines was given a certain space to watch and to prevent the
natives from approaching too near. Captain VAN DER MEULEN was exceedingly
anxious to render all possible assistance.

Everything appeared to be most favourable until about 2 P.M. on Decem-
ber 8, when clouds began to drift from the mountains towards the sea. The
natives crowded in hundreds at a short distance to watch our proceedings,
but in no way whatever did they disturb us. An hour before the predicted
time the adjustments and motions were examined and found to be in good
order. The micrometer and eye-pieces could be interchanged easily in
15 seconds.

Time by the
Transit-Clock.

20. 21.

20. 30.

20. 34.

20. 38. 30.

20.41.

20. 48. 50.

Clouds obscured the Sun. They continued off and on for some
time.

Clouds still continue. I have almost given up hopes of using
the double image micrometer before internal contact on
account of the clouds. Airy's eye-piece is inserted with a
graduated neutral tint glass.

Clouds off. Planet nearly half way on. Limbs of Sun and
Venus boiling badly.

PlaneT more than half way on, seen through thin clouds with-
out the dark glass. Limbs of Sun and Venus sharp.
Silence " called.

Clearer. Tried micrometer. Clouds immediately came over.
Changed to Airy's eye-piece.

The edge of Venus, outside the limb of the Sun was shown by
a fine line of light, not visible quite all round, (and therefore,
more correctly speaking, it was shown by two fine lines of
light). The thread of light at the north cusp was longer
than the other.

FORBES' OBSERVATION OF INGRESS. 221

Time by the
Transit-Clock.

has

20. 50. Mr. Lloyd began to count seconds aloud from inside the

transit-hut, but the Sun became obscured by clouds.

21. 8. The planet is well on. The clouds are partially dispersed.

The double-image-micrometer inserted ; the following
distances of limbs measured : —

h m « r bmi i

21. 9. 3o 21'OOD 21.14.11 20*346

10. 1O 20'80O 14.66 2O'l54

11. 3i 2o'6o2 1 5. 23 20*209
12.23 2o-568 16.40 20-029
i3. 5 2o'3i3 45* 19-866
13.43 20-486 ig. 14 ig'756

* Minute not recorded.

The measures of distances of limbs were discontinued when that distance
was about equal to the diameter of Venus, as shown by the overlapping of
the two images of Venus.

So far as I can judge, the observations are sufficiently regular to lead to the i
belief that the micrometer was working well, in spite of a fall it had pre-
viously.

Measures are now taken of the diameter of Venus, to serve as a measure
of one revolution of the micrometer-screw, and to determine the zero
reading.

Micrometer Readings.

18-961
i8-g3g

Considerable boiling. Images cannot be made equally bright by means of
the adjusting screw.

Images made equally bright by revolving the body of the micrometer.

Micrometer Readings.

r

ig-o33
i8-9g9
ig-o55

F F 2

222 TRANSIT OF VENUS, 1874. KAILUA.

Eeadings were now taken with the opposite edges of the images in contact.
Boiling of limbs very bad.

Micrometer Eeadings.

r

26-872
26-993
26'ggo
26'g52

G. FORBES.

The Equatorial Telescope, its mounting and driving clock, which were
purchased by the Government from R. Hodgson, Esq., were almost the
counterpart of the " Bedford " Equatoreal, described by Admiral Smyth in
the Cycle of Celestial Objects.

The object-glass, supposed to be by Cauchoix, was six inches in diameter,
but the effective aperture was 5'7 inches, and the focal length was 75 inches.
Professor Forbes describes its defining power as admirable.

At Kailua the long polar axis was supported by a massive framework of
timber, which had been constructed at Greenwich, and adapted very nearly to
the requisite latitude. The instrument was used in the open air, and when
out of use was protected by a large tarpaulin.

The double-image-micrometer and solar diagonal reflector were made by
Messrs. Troughton and Simms ; the former was kindly lent to the Astronomer
Royal by J. G. BARCLAY, Esq., of Leyton, Essex. It was accidentally injured
by a fall just before the transit of Venus ; the injury, however, appeared to
be confined to the outer portion of the screw which carried the milled head
(Plate III.).

It is unfortunate that all Professor Forbes' micrometer readings for distance
of limbs were on one side of zero. He states also that the images could not
be made equally bright, by means of the adjusting screw, without rotating
the body of the micrometer; a circumstance which tends still farther to
diminish the value of the measures.

The only clue to the zero reading of the micrometer, before it was rotated,
is the first set of three readings for the diameter of the planet, the mean of
which is 18r'972. After rotation the next set of three gives 19r-029,
showing an apparent increase of the zero reading of '057. The zero obtained

EQUATIONS FROM FOEBES' OBSERVATION OF INGRESS. 223

from the Second and third sets is 22r-990 ; hence the zero proper to apply to
the readings for distance of limbs is 22-990 - '057 = 22r>933.

Using the tabular semidiameter of Venus as before, we have for the value
of one revolution of the micrometer screw —

_ 3i"-42+8r _ 5,,.g63 + .5 58
^(26-902 — ig'oag)

The following equations have been formed with the values p = 15"'863
+ -505 8 r ; R = 976"-80 ; r = 31"'42 ; and assuming the latitude and
longitude to be 19°. 38'. 23" N., and 10h. 24m. 28'7 "West, respectively. The
revised longitude being 10h. 24m. ls>7 W., 8 t = — ls>0 on this account. The
correction to the Transit-Clock has been assumed to be + 32S<03.

G. L. T.

224

TRANSIT OF VENUS, 1874. KAILTJA.

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ADJUSTMENTS OF THE TRANSIT INSTRUMENT.

225

TABLE I. — LEVEL ERROR of the TRANSIT INSTRUMENT at KAII.UA, determined by SPIHIT LEVEL.

The sign + indicates that the East Pivot is low.

Sidereal

Level Error

Sidereal

Level Error

Time

Position

corrected for

Time

Position

corrected for

Day.

of Level

of

Inequality of

Day.

of Level

of

Inequality of

Determination.

Lamp.

Pivots.

Determination.

Lamp.

Pivots.

1874.

h in

„

1874.

h m

„

November 23

22. 5o

E

+ 7'9°

December 3

i. 5

E

+ 10-78

23. O

E

+ 8-o5

1.25

W

+ 12-88

23. 2O

E

+ 8-10

2. I 5

W

+ 11-28

i. 5

TV

•f 9-28

3. 55

E*

+ 12-28

i. So

W

+ 9-20

4. 10

E

+ I2-lS

3.40

AV

+ 9-52

4. 3o

E

+ 17-53*

4-44

W

+ 9-60

5.2!

W

+ 9-52

4

o. 5

E

+ 12-08

0.25

E

+ 12-50

24

i. 4

W

+ 9-85

o. 40

E •

+ 11-93

i.4S

W

+ 9'?8

I. 10

E

+ ii'go

2. 4

W

+ 9'9?

2.25

W

+ i3-88

4. 3o

W

+ 8-73

2.55

W

+ 13-70

5.55

W

+ 9 '4°

6

4.i5

W

+ 14-35

26

6.25

W

+ 10-93

4. 3o

W

+ i3-65

6.45

\V

+ 9-93

4.45

E

+ 12-70

7.3o

W

+ to-55

5. o

E

+ 12-55

8. 5

W

+ i i -80

7

2. 40

E

+ n-83

28

o. 10

W

+ I2'l5

3. 55

E

+ 11-73

o. 3o

W

+ 12-12

4.42

W

+ i3-i5

I. 0

W

+ 1 2 ' 22

3o

o. 3o

E

+ II'28

9

o. 4$

W

+ 13-85

o. 45

E

+ II '28

i. 5

W

+ '4'43

i.3o

E

+ 10-85

1.23

E

+ 12-73

i. 5o

E

+ I2'50

December i

0.40

E

+ IO-93

2. 13

E

+ 11-95

i. 5

E

+ lo-SS

2. 3o

E

+ 12-88

I. JO

W

+ 12-63

i. So

W

+ I2'l3

ii

I. 10

E

+ n-83

I. 22

w

+ i3-88

2

0.25

W

+ I2'l3

i. So

W

+ 13-53

* Lamp left on ; for the other readings it had been removed.

226

TRANSIT OF VENUS, 1874. KAILUA.

Sidereal

Level Error

Sidereal

Level Error

Time

Position

corrected for

Time

Position

corrected for

Day.

of Level
Determination.

of
Lamp.

Inequality of
Pivots.

Day.

of Level
Determination.

of
Lamp.

Inequality of
Pivots.

1874.

h m

K- //

1874.

h m

//

December i3

I. IO

W

+ i5-o5

December 29

I. IO

W

+ 12-68

1.26

E

+ 15-38

I. 2O

E

+ io-i5

i.5o

E

+ l6'20

2. 22

W

+ 12-75

12. 45

W

+ 12-75

H

0.45

E

+ i3-o5

I. 12

E

+ i3'i7

3o

i3. 28

W

+ 12-00

i5

23. 3o

E

+ 12-40

' 4. 20

E

+ 12-62

3i

I. 0

E

+ io-o3

5. So

W

+ 14' 20

1.25

W

+ 12-35

i3. o

W

+ ii-io

16

10. 3o

W

+ I4-55

II. 0

E

+ 13-70

i875.

January i

22. 45

E

+ 10-78

J7

i. 5

W

+ H'?*

4. 5

E

+ 8-53

i. 3o

E

+ 12-95

i5. o

W

+ io'o8

3. 18

E

•f i3'io

3.55

W

+ i5-5z

2

i. 9

W

+ 9'65

1.23

E

+ 8-83

18

I. IO

W

+ i6-i5

2. 40

W

+ 10-60

1.25

E

+ i5-oS

16. 3

E

+ 7-35

20

0,52

E

+ iS-55

3

i. 5

W

+ 10-25

1,22

W

+ i6-75

i. 3o

E

+ 8-65

17. 3o

E

+ 8-o5

21

i. 5

E

+ 14-93

1.25

W

+ 16-73

5. 3o

E

+ 16-38

4

5.35

E

+ io-i3

6. 14,

W

+ i3-i8

22

0.52

• E

+ to-63

1.27

W

+ 11-73

12

o. 40

E

+ ii -60

6.25

E

+ Ii-o5

i3

5.45

E

+ 10-83

28

2.16

E

+ 11-18

2.47

W

+ 12 -2O

'9

3.45

E

+ n-55

1 5. 3o

E

+ 10-18

ADJUSTMENTS OF THE TRANSIT INSTRUMENT.

227

TABLE II. — AZIMUTH ERROR of the TRANSIT INSTRUMENT at KAILUA.
[The sigu + indicates that the East Pivot is too far North.]

Day and
Approximate Mean
Time.

Stars used for Azimuth Error.
The letters (E, W) refer to the Position
of the Lamp.

Azimuth Error

By Stars.

By Meridian
Mark.

Adopted.

1874.
November 2 3
24

26

26
28

3o
December i

2

3
4

6
7
9
ii
13

'4
i5

16

17

18

18
'9

20
21

22

27

]i

9
9

'4

•5J

9

8

01

«>2f

H
•i

9

12
II

8
8
8
8

i3
i3

'7
8
8

9

5

74

5

7
7
7
5

Polaris (E, W) and v Piscium

//

- 37'2

- 36-4

//

//

- 37-5
- 36-4

Polaris (W) and 8 Ceti

- 52-1

—

- 52-1

A. Ursse Minoris S.P. (W) assuming the clock ]
correction + 9*- 1 5 J

- 35-3
- 21-7

— 22 '2

- 18-0

- 20-7
- 17-2

- 5-i
- 3-9

- J4'4
- 5-o
- 6-2
- 7'o
- 2-8
- 11-9

- 16-8
- 17-1
— 10-8
- i6-5
— 18-0
- 18-0

- i6-3
- i6-3

- 35-3
} - 21'9

- 21-3

— 20 '7
— 19-0

- 17-2

} - 4'9

- 14-4
- 5-7
- 6-2

- 7-0

- 2-8

- 11-9

- '4'4

} ~ '6-9

- 12-7

I 17-8

Polaris (W, E) and Bradley 1730 S.P. (W)

„ „ i73i S.P. (W)

6 Stars between N.P.D. 63° and 109°

Polaris (E, W) and j8 Ceti

Polaris (E, W) and Piscium

Polaris (E, \V) and v Piscium

Groombridge 2o53 S.P. (W) and 69 Ceti

6 Stars between N.P.D. 57° and 1 1 3°

8 Stars between N.P.D. $9° and 106°

Polaris (E, W) and v Piscium

Polaris (E, W) and e Piscium

Polaris (W) and /3 Andromedas (W)

Polaris (E) and o Piscium (E)*

S Ursa; Minoris S.P. (W) and a Orionis

24 Ursse Minoris S.P. (W) and o Orionis

9 Stars between N.P.D. —6° and 109°

Polaris (W) and 53 Arictis

Polaris (E) and 3 1 Tauri

B Ursa; Minoris S.P. (W) and 3i Tauri

Polaris (E, W) and Bradley 1731 S.P. (W)

+ 45-5

+ 45*2
+ 46-0
+ 43-o

+ 44'°
+ 47'3
+ 44-6
+ 44'°

+ 46-6

+ 45-5

+ 45-3
+ 46 'o
+ 43-o

Polaris (E, W), Bradley 1731 S.P. (E)

Polaris (E, W), Groombridge 2o53 S.P. (W)
Polaris (E, W), Bradley i?3i S.P. (E)

* Azimuth disturbed by act of reversal.

G G

228

TRANSIT OF VENUS, 1874. KAILUA.

Day and
Approximate Mean
Time.

Stars used for Azimuth Error.
The letters (E, W) refer to the Position
of the Lamp.

Azimuth Error

By Stars.

By Meridian
Mark.

Adopted.

1874.
December 28
29
3o

3i

1875.
January j

2

3

4

12

i3
19

ii
8
7
'9

5i

7
7

7

4
9
20

7
7
8

21

5
6
6
8

22

9
9

IO
10

'9
!9
5
8
9

1 1 Stars between N.P.D. 67° and 106°

//

+ 5o-8
+ 44'3

//
+ 46-6
+ 46-0
+ 47'9

//

+ 44' 3
+ 44'3

Polaris (W, E), Groombridge 2o53 S.P. (E)
Bradley 1731 S.P. (E), a Eridani

— 14-0
- i3-o
- 21-7

— 29 'o

- 24-5
- 11-4

— IO'I

- 9-6
— io-9
- 6-1

- 4'7
- 6-6
- 1-4
- 7'S

+ 44'o
+ 37-S

- 10-8
- 23-9

- 21-3

- 6-9
- 10-8

- 5-6

- 8-2

+ 44'°
+ 49'2

L - i6-3
- 26-6

}.:.,

> — I0'2

I ;,..

+ 44'o
+ 37-9

Polaris (W), o Eridani*

7 Stars between N.P.D. 71° and n5°

Polaris (W) and S Arietis

Groombridge 2o53 S.P. (E) and 62 Ceti

Polaris (W), clock + 20" '97

Polaris (E), „ + 2os * 76

0 Ursa? Minoris S.P. (W), „ +2is-o7

e Ursa? Minoris S.P. (E), 3 1 Orionis

Piazzi IV. 3 1 7 (E), 3 1 Orionis

5 Urssc Miuoris S.P. (W), 7] Geminorum

S UrsiE Minoris S.P. (E), 3i Orionis

5 Stars between N.P.D. 1 1" and 87°

4 Stars between N.P.D. 71° and 104°

* The act of reversal evidently disturbed the Azimuth on these occasions.

ADJUSTMENTS OF THE TRANSIT INSTRUMENT.

229

TABLE III. — OBSERVATIONS of the MERIDIAH MARK at KAILUA, and its CONCLUDED AZIMUTH.

Day and

Approximate Mean
Time.

Center Wire apparently
Left of Center of Image of
Copper Scale.

Center of Mark
West of
Optic Axis.

Azimuth Error,
as determined by
Stars.

i

Center of Mark
apparently West of
North.

Lamp E.

Lamp W.

1874.

i

di».

lllT.

//

//

//

December 17

4}

+ 3-i

+ 4-o5

+ 93-3

- i7-3

+ 76-0

18

5*

H

+ 3-i

+ 4-0

+ 92-7

1 ' '

+ 78-1

+ 0-8

+ 1-7

+ 3z-6

+ 45-5

19

s

0-7

i-55

29-3

20

5

0-8

i-65

32-0

+ 45-3

+ 77-3

21

H

0-8

''7

32-6

+ 46-0

+ 78-6

24

Noon

o-gS

i-75

15-2

22*

i-o

i-75

35-8

25

5

!••

i*7

35-2

«|

I'O

1*7

35-2

27

5

o-S

i-5

3o-o

28

5

0-8

i-5

3o-o

•

21

0-8

i-5

3o-o

29

5

o'75

1-6

3o-6

+ 44'3

+ 74' 9

3o

'9
'9*

+ o'75

+ 1-45

+ 28-7

+ 2-8

+ 3-7

+ 84-8

3i

si

2-9

3-8

87-4

- i3-o

+ 74' 4

1875.

January i

4

3-5

4'*

ico'5

20

3'4

4''

97'9

2

3
4

21

5

22
'9

2-8
3-o
2-8

2-9

3-6

3-7
3-5

1-6

83-5
87-4
82-2
{ 84-8 -i
I 32-6 •"/

- n-3(?)

— I0'2

- 7-o (?)

+ 72-2 (?)
+ 77-2
+ 75-2 (?)

12

5

+ 0-7

+ 1-4

+ 27'4

The adopted Azimuth of the Center of the Meridian Mark is 76" -6 West of North, and the adopted Value of One
Interval on the Copper Scale, 26" -2.

G G 2

230

TRANSIT OF VENUS, 1874. KAILUA.

TABLE IV. — TKANSITS of STABS and of the MOON observed at KAILUA, by Professor G. FORBES.

Day.

Position of the
Illuminating
Lamp.

Object observed
and
(Number of Wires).

Mean observed
Clock-Time
of Transit over the
Center Wire.

Seconds of
True Transit
over the
Meridian.

Seconds of
Star's
Assumed
Apparent R.A.

Clock
apparently
Slow.

1874.

November 2 3

H
26

E
W

W

W
W

W

23. 10. 23 '24
23.20. 13-58
23.33. 13-34
I. ii. 33-79
i. 10. 42-46
i. 34.35-5o
i. 59. 46-23

2. 10. 25-07

4. 20. 59-39
4. 28. 25-49
4.41. 14-09
4. 59.53-05

5. 8.13-96
5.i8. 3-72

I. 10. 54'

i. 17.41-62
1.24.41-47
i. 34. 5o-i2

2. 0. 2-47
2. IO. 41-24
4. 28.40-09
4.48. 45-20

5. 7.20-33
5.25.33-io
5.35. 5-56
5. 5o. 10-19

6. 3o. 19-60
6. 39. 3o-63
6.53.35-94

7. 45. 58-
8. 2. 8-63

m f
22-35

12-61

12-57

12. 53'27

12.58-oS
36-n

47-75
25-i6

0-70
26-68
15-93

52-52

14-06
5-63

i3. 6-98
41-69

42-57
So- 77

4'oi

41-38
41 -3o
47-36
23-65
33-55
4-43
12-14

20-77
29-78
34-26

48.22-77
10-72

8
40-54

3i-oo
3o-83

12-52
12-52

55-77
7-90
45-33

19-51

45-37

II -OI

32-41
23-88

12-08
46-76
47-82
55-77

7-90
45-33
45-38
5i-75
28-02
37-74
8-49

29-73
38-73
43-35

3i-77

+ 18-19
18-39
18-26
19-25
14-49
19-66
ao-i5
+ 20 • i 7

67 Ceti

e Tauri

+ 18-81
18-69
[i8-63]
18-49
18-35
18-25

5-io
5-o7
5-25
+ 5-oo

Moon II

Rigel

0 Tauri

Polaris (i)

8 Ceti

+ 3-89
3-95
4-08
4-39
4-37
4-19
4-06
[4-38]

8-96
8-g5
9-09

9-00

+ [9-i3]

67 Ceti

A Urss Minoris S.P. on")

November 23. The clock was stopped at 2h. 3o™, Sidereal, to lengthen the pendulum. The seconds for j> II. at each wire
are 47"8, o"-5, i3"9, 27"-6, 4i"2. Sum of instrumental corrections, +i"'76; correction applied for }) 's motion

November1 24. ij Piscium and i Auriga;, the illumination nearly failed. The seconds for 5 II. at each wire are 43'- 1, 56»-6,

io'-i, 24'-!, 37*'7. Sum of instrumental corrections, +i'-86; correction for J 's motion in R.A., +os-o9. The clock

was stopped at ih. 5om, Sidereal, to lengthen the pendulum.
November 26. J II. 42" i, 55" 3, 8"- 5, 22" i, 35"8. Sum of instrumental corrections, +2'-oo. Correction for J 's motion

in R.A., +o!-o9. The level -was adjusted before the observations. The Azimuth was partially adjusted on \ Ursa;

Minoris' S.P. with wire d. The sky then clouded over.

MERIDIONAL TRANSITS.

231

Day.

Position of the
Illuminating
Lamp.

Object observed
and
(Number of Wires).

Mean observed
Clock Time
of Transit over the
Center Wire.

Seconds of
True Transit
over the

Meridian.

Seconds of
Star's
Assumed
Apparent E.A.

|

Clock
apparently
Slow.

1874.
December 6

W

e Tauri

h m s

40-85

a

10*68

+ 29*83

Bradley 6s5 (4") . .

4. 25. 53-43

29-56

20*55

4. 28. 14*68

I6-26

45-54

29*28

4.. 38. 4.5*01

46'J6

15-89

20' 71

E

A. 4.8. 22' 2O

22-66

5i'95

20* 20

A. So. 4.2* 3o

41-63

1 1 - 16

29*53

7

E

tr Ceti

2. 25. 30*08

3q' 7A

3o*65

5 Ceti

2. 33. 3A-4.5

34-4.1

5-02

3o-6i

3. 45. A6* 32

46-55

17- 18

3o-63

3. 5i. 42' 26

12-63

3o-5o

i5-8i

46-57

3o-?6

10*66

41 '4.5

3o*70

W

4. 28. 1 3 * 22

14-78

45-55

3o* 77

4. 38.4.3-57

£4 ' 87

I 5 * QO

3i *o3

9

W

£ Ceti

o. 36.43*38

A A ' "--I.

18-90

34,- 36

37-26

n-63

34-37

O. 40. 12* 30

14* 5i

48-76

34-25

o. 55. 51-69

53*i7

27-31

SA- IA

Polaris (4)

i. ii. 3o* 32

22. 28*55

2-73

34-18

E

I. 12. 27'23

28 * QO

2-73

33-83

I. 34. 21'62

21-66

55'7i

34-o5

i. 47. 10*00

IO' 2O

44*24

SA'OA

£' Ceti

2. 5.48'95

4-0 * 04.

22-80

33-76

67 Ceti

45 -3o

33*68

£2 Ceti

57-52

3i-i3

33*6i

i/ Ceti

2. 28.45-33

4-5-37

IQ ' 22

33*85

•y2 Ceti

49*85

33*84

E

5 Piscium

26* QQ

1 1 * 5o

67 Ceti (A) . .

2. IO. 0*71

45*28

44-83

i5

E

Moon I. (4)

23. 25. 0*93

o-5i

["46-661

54-63

4.1 - 5o

A6'87

r Tauri

4. 1 6. 16-78

16-76

3*67

4-6* QI

Aldebaran (Obs.G.L.T.)
55 Eridani

4.27. 58 -5o

58*62
AS -72

45-59

35*77

46*97

u.7*o5

i Tauri

iy-o3

4*5i

^7*48

W

4 53. 19*86

8*12

47*38

c Leporis(Obs.G.L.T.)

4. 59. 21- 8z
5. 6.40-18

23-49
4i'o3

11*23

2S*5o

47 '74
47*47

5 ii 5i-83

53-04

AO* 80

47-76

f Orionis (Obs. G. L. T.)

5. 19. 19-28
5 33. i5-68

3o-5o
i- -26

18*20
4* 16

47-70
+ 46*90

December i5. J I. , 48'*2, i"*o, I2'*8, 24"*4. A mistake of i1. has been assumed tt the second wire. Sum of

instrumental corrections, — 0^*40 ; correction for J 's motion in K.A., — o'-oi. Four stars observed by Captain
Tupman.

232

TRANSIT OF VENUS, 1874. KAILUA.

Day.

Position of the
Illuminating
Lamp.

Object observed
and
(Number of Wires).

Mean observed
Clock-Time
of Transit over the
Center Wire.

Seconds of
True Transit
over the
Meridian.

Seconds of
Star's
Assumed
Apparent R.A.

Clock
apparently
Slow.

1874.
December 1 5

16

W

W

o Orionis (Obs. G.L.T.)
S Ursa; Minoris S.P. (i)
24 Ursa; Minoris S.P. (3)

h m s
5.47. 36-48

6. 12. 5-64
6. 16. 32-o8

10. i3. 43 '47

m s

37-80

ii. 3i-gi
1 5. 54-00

44-80

K

z5-o5
19-36

41-57

34-29

S

+ 47'25
47-45
47-57

40*40

10. 16. 16-41

17-62

7-37

4.0* ?5

10. 23. 2-67

3-96

53-93

49" 97

IO. 27. 37* 22

38-68

28-59

49*91

E

b3 Hydra:

10.46. 33 -So

32-99

22-33

49" ^4

Bradley 3o5S S.P

10. 54. 26-61

23-n

12-68

49-57

n. 6. 37-26

37-55

27-36

49-81

11. 12. i5-g8

i5-6i

5-07

49-46

A Crateris

ii. 1 6. 20*68

20-20

9-69

49-49

17

W

Polaris (3)

i. 10. 38-97

12. 8'7i

56-25

47-53

W

i. 7.41-83

43-24

[5i-o8]

E

i. ii. 32-33

12. 5-o5

56-25

5l'2O

o Ceti

2.54. 54-65

54'5i

45-23

50-72

S3 Arietis

z. 59. 33-oo

33-i8

23-92

5° '74

3. 3.38-36

38-57

29-40

5o-83

3. 6.52-54

52 -So

43-5i

50-71

96 Ceti

3. ii. 58-i3

57-96

48-89

5o-o3

W

3. 20. 3?' QI

39-12

3o-32

5 1 -20

6 Ursa; Minoris S.P. . . .
3i Tauri

3. 34.23-78

3. 44.. 28* OI

I4-55

29-36

5-84
20-98

5i-29
5i-62

3. 4.7. 32*70

33-35

24-64

5i -29

3. 5i. 20*62

21-47

12-66

5i • 19

co1 Tauri

4. i. 0*88

2-60

53-74

Si' 14

"2.1

E

I. I4-. 6* IQ

ii. 52-45

5i-77

59-32

W

Polaris (3)

I. l3. 6*44.

11.49-44

5i-77

62*33

Groombridge 2o53 S.P..
o- Ceti

i. 40. 56* 14

2. 25. 7* 12

41. 7-48

10-62

8-08

10-34

60*70
59*72

S Eridani

3.36. i3-32

i6-5o

i6-35

59-85

E

3 1 Tauri

3. AAT 20* 85

21 -QI

20-98

5q*O7

3. 5i. u*i6

l3'Oq

12-65

5g-56

3. 56. 7-07

8*i5

7-73

5g-53

5. 10. 16* 97

17*01

[59-651

ft Tauri

5. 17. 24*63

24* 57

24-35

59-78

1 1 8 Tauri

36*i6

35-8o

59-62

B.A. C. 1746

5. 27. 6* 27

6*25

5-84

5o-5o

E

Bradley 1731 S.P

4.7. 14.* 22

15-86

61-66

i. i3 55-36

1 1, 4.5 '44.

5i-o5

65-6i

W

i. i3 7*o5

II. 62*92

5i-o5

+ 58-i3

December i5. 3 Ursac Minoris S.P. on wire b at 6h. 17™. 3s.

December 17. B I. 18" i, 298-9, 4i"-8, 54s-o, 5!'9. Sum of instrumental corrections, +i«'36; correction for ]) 's motion

in RA., +o"o5.
December 2i. J I. 49"8, 2!-8, i7"-i, 3os-3, 44s-2. Illumination bad. Sum of instrumental corrections, +o'- 04.

MERIDIONAL TRANSITS.

233

Day.

Position of the
Illuminating
Lamp.

Object observed
and
(Number of Wires).

Mean observed
Clock-Time
of Transit over the
Center Wire.

Seconds of
True Transit
over the
Meridian.

Seconds of
Star's
Assumed
Apparent R.A.

Clock
apparently
Slow.

1874.

\V

70 Ceti

h ra a
2. I4-. 4.5*77

in a

48*l3

s

5o-68

s

+ 62-55

71 Ceti

2. 17. 34.* 60

39-76

62-55

2. 20. 26-85

28-87

3i*o8

62-21

3-66

E

S Ceti

2. 32. 2*10

3-17

4-*o6

6l * 70

7 Ceti

2. 34. 46' 97

4-0* 7O

61*88

2. 41. 17*40

I7*6l

IO'4-O

61 * 70

6. 21. 29*88

[62-201

1875.

W

Polaris (3)

i. i o. 40* 53

4-2" 07

E

I. 12. U ' 71

12. 23*OO

4-2*07

10* 07

I. 34.. 36*27

36*oo

55-52

10* 52

i. 38. 28-o5

27-83

47-53

10 * 7O

t

Groombridge 2o53 S.P. .

i. 41. 50*29
i. 47. 24- 52

49-36

9-42

20*06

19* 59

i. 5o. ii -98

11*89

3i'3

10*4-5

57 Ceti

i. 53. 34-68

33*04.

53-69

10" 75

i. 55. i5-6i

34-*OO

10* 60

i. 5o. 4.8 *o6

4.8 *o5

7*68

ig-63

62 Ceti

2. 2. 3o*67

4.0*00

10* 7O

63 Ceti (4)

2. 4.55*36

2O*26

W

S Arietis (4)

2. IO. 48*95

5o-35

10*4.7

2O* 12

69 Ceti

2. l5. II "35

12* 3o

32-64

2O "25

2. 17. 4.5* 02

4.7* I 3

7*24.

2O* II

w Ceti (3) . .

2. 21. 9* 67

10*82

3i*oo

20* 1 8

„ Ceti

2. 28. 57*91

59-03

10* 08

2O*o5

2. 32. 43'7I

4-89

20* 14.

"

Ceti

2. 36. 28*45

20* 54.

4-0" 74.

2O *2O

3

W

i. 1 1. 16' 39

4.O" 60

10*32

E

I. 12. 0* 60

4.O*6o

22' 6l

69 Ceti

2. I 5. I2*OI

11*68

32-Sg

2O '01

Lalande 4458 (3)

2. 17. 29* 1 3

28*27

4.0* I 5

20*88

<r Ceti (4)

2. 25. 4.0*74.

IO*23

21*08

v Celi

2. 28. 58*71

58-4.5

io*o5

20*60

2. 3 1. 22*74

22'68

43-37

20*69

W

*f Ceti

2. 36. 27*45

28-57

21 ' l6

2. 4.1. 56* q6

58-3i

IQ'32

21 *OI

9..- 44, T V ^?,

I4.-83

35-77

2O* 04.

£ Ursac Minoris S.P
a Ceti

2. 50.47*42
2. 55. 22*00

42-20

24." 1 3

4-23 '
4-5 * 1 5

22-03
21 -O2

3. 4. 6-70

8-n

29-33

21 '22

E

4.. 4.8. 58* 06

58-66

21 '46

22-80

4

4. 5i. 39^87

2*49

+ 22-82

December 22. J II. , l6i-i, 3o'-o, 438-5, 56"-8. Sum of instrumental corrections, — o"4o; correction for j) 's motion

in R.A., — o"-oi.

January 2. The act of reversal appears to have disturbed the azimuthal adjustment. Observer's eyes fatigued.
January 4. Observer's eyes fatigued. 5 Ursa Minoris S.P., Lamp E, on wire k at 6h. 18™. 33'.

234

TRANSIT OF VENUS, 1874. KAILUA.

Day.

Position of the
Illuminating
Lamp.

Object observed
and
(Number of Wires).

Mean observed
Clock-Time
of Transit over the
Center Wire.

Seconds of
True Transit
over the
Meridian.

Seconds of
Star's
Assumed
Apparent E.A.

Clock
apparently
Slow.

1875.
January 4

E

W
E

e Ursa; Minoris S.P. . . .

h in s

4. 58. 18-89
5. 7. 5-88
5. 9-53-44
5. i5. 53-35
5. 19.45-21
5.23. 0-95
5.25. 14-85
5.28. 33-79
5. 33.41-80
5.41. 26-30
5.47. 8-32
5. 52. o-oi
5.56. 7-14
6. o. 2-16
6. 6.55-78
6. 12. 11-62
6. ii. 55-88

m s
21 ' 19
5-69

52-88
53-3o
45-33
0-86

'4'77
33-68
41-82
27-65
9-95
i-43
8-82
3-71
57-55
ii. 53-21
o-33

s

43-56
28-58
I7'o3
16-71
8-64
24-11
38-ig
56-98
5-41
50-69

33-74
24-95
32-36
27-11

21 -OO

i8-5i
i8-5i

+ 22-37
22-89
24-15
23-41
23-3i

23-25

23-42
23 -3o
23-59
23-04
23-79

23-52

23-54
23-40
23-45
25-3o
•4- 18-18

Piazzi IV.
m Orionis
114 Tauri
3 1 Orionis
8 Orionis .

3i7 ..

Bradley 80
126 Tauri

X2 Orionis
60 Orionis
i Geminor

(A) ..

T) Geminor
$ Ursae Mi
8 TJrsse Mi

noris S.P. (3)
aoris S.P. (i)

TABLE V. — EREOKS and RATE of the TUAKSIT-CLOCK at KAILUA.

Day.

Sidereal
Time.

Clock
Slow.

Clock's
Loss in

24".

Adopted
Losing
Rate.

Day.

Sidereal
Time.

Clock
Slow.

Clock's
Loss in
24".

Adopted
Losing
Rate.

1874.
Nov. 2 3

*4

26
28
3o
Dec. I

2

3

4
6

7
9
ii

h m
23.22
1.55

4.51

1.23

4- 14
6.41

O. II

i. 8
i. 16

3. 18
3. o
i. 18

4.42

4. 2
1.28
I.I7

8

+ 18-28*
+ 19-99*

s

+ 16-0

i
+ 16-0

1874.
Dec. 1 3

'4
i5
16

'7
18

21
22
28
29
3l

1875.

Jan. i

2

3

4
i3

'9

h m
I.4I
1.26

4.5of
10.44
3.26

I. 21

3. 5o
2.29

2. 30

1.34

3.32

3.56
2. 9
2.36
5.35

2. 5l

3.54

+ 42-30
44-87*
47-21
49-66
5i-o4
52-8i
59-66
62-09
i3-3o
14-52
16-91

18-60*
19-92

20-95
23-33
45-93*
+ 57-90*

H
+ 2-06

2 "60

2-o5

1-96

I-87
I'94
2-21

2-58

I-87
1-27

1-16

1-68
1-63
I -02

2'12

2-53
+ 1-97

3

+ 2-33
2-33

2-01
I-90
I-9I
2-01
2-49
2-48

i-36

1-23

i-5i

i-65
i-33

i-57

2- 12

2-5o

+ 2'OO

+ 18-37*
+ 4-96*

-iS-63

-iS-63

+ 3-98*
8-75*
13-09*
17-26*
19-64
21-58*
23-44
25-35
29-50
30-79
34-05
+ 38-i8

+ 2-27

z-5i
2-o5

2'37

1-79
1-89
2-o5
i-93

i-43
i-73
+ 2-08

+ 2-27

2"39

2-28
2-26
2-08
1-84

1-97

2'OO

i-58
i-53
1-91

+ 2-07

* Instrument used in one position only.

f December i5, 4h. 56m, clock slow +47'- 26. Observer, Captain Tunmau.

TRANSIT OF YEN US, 1874.
PART I.

EXPEDITION TO THE HAWAIIAN ISLANDS

(continued).

Section 3.
OBSERVATIONS AT WAIMEA,

BY E. JOHNSON, ESQ.

H H

236

CONTENTS.

PAGE

The Site at Waimea ...... 237

The Transit Chronometers --.....„

The Transit Instrument - - - - . „

Value of one revolution of the Transit Micrometer Screw ... 238

Equatorial Intervals of the Wires - „

The Level Error - „

Error of Collimation ... 229

Error of Azimuth - - „

Transits observed at Waimea - „

Latitude of Waimea - - - 240

Longitude of Waimea - - „

Report of Mr. R. Johnson on his Observation of the Ingress of Venus, 1874,

December 8 - - - - 241

Mr. R. Dunn's Observation of the same - - 243

Final Equation for Waimea - - - 244

Observations in Tabular Arrangement : —

Table I. — Transit Instrument, Level Errors - - 245

II. — „ „ Collimation Errors - 246

III. — „ „ Azimuth Errors - „

IV. — Transits observed at Waimea - . 247

V. — Comparisons of the Stationary Chronometers - - 252

VI. to VIII. — Errors and Rates of the Chronometers ... 253

Plate VII. — Plan of Waimea - - - to face 237

Plate VII.

Transit of Venus, 1814 Dcf.6'.

Plan of tlie VUlciye of Wairnea.on tJie Island of Kauai,
slwwirig the position of A/T Johnsons Obscn'olory.

\_\Sione Church

(Observatory
Latitude 11° 57.2V
Longitude Wh38 ™ 40s W.of

\

J. W, Gay , Survyer. 1874 Dec

Riissitin
/ Fort.

Iff fan. page 23%.

OA«GC«FICIO LlTH.22 BtOFORD Sr COVENT

TRANSIT OF VENUS, 1874. 237

OBSERVATIONS AT WAIMEA, ISLAND OF KAUAI (ATOOI).

BY RICHARD JOHNSON, ESQ.

Mr. Johnson, accompanied by Sub-Lieutenant R. H. Wellings, R.N., and
some artificers, left Honolulu for Kauai, 1874, November 6. Receiving much-
friendly assistance from Mr. Kanutsen, the principal resident, he found at
Waimea a suitable dwelling-house with convenient ground around it, a
portion of which was fenced in for the observatories. The position with
regard to surrounding objects was surveyed and plotted, as in the accom-
panying plan, by Mr. J. N. Gay, Surveyor, of Honolulu. It was about
80 feet above the sea, and half a mile inland from the landing-place. The
exact site of the transit pier, in case of its removal, could be recovered from
the following description : — Near the edge of the rocky cliff overhanging
Valley Road, 35 feet E.S.E. from the S. corner of the dwelling-house, a
mark /f\ has been chiselled in the rock and filled with cement. From this
spot the bearings below were taken : —

O I

Lehau Island, highest peak - - N. 8 1 . 1 2 . W. (true)

Old Russian Fort at mouth of stream - - S. 12. 5o. E.

Sharp Peak in Kauai Range - - N. 67. 5o. E.

Transit pier, distant 23i feet - S. 78. 55. W.

Two similar marks were cut in the rock on the edge of the cliff to the
S.W., distant 90 and 346 feet respectively from the above-mentioned mark,
and distant 174 and 199 feet respectively from the transit pier.

Mr. Johnson was provided with a transit instrument and three chronometers
for obtaining local time. The chronometers are those named J, L, and N in
the list at page 31. The dial of N was divided to 24 hours ; it was regulated
to Sidereal time, and Mr. Johnson used it when observing. Chronometer J,
with 12-hour dial, was also regulated to Sidereal time, while L was a mean-
time chronometer. The three were kept on the transit pier and inter-
compared (by coincidence of beats) twice a day (Table V.).

The transit instrument, which was kindly lent to the Astronomer Royal
by REGINALD BUSHELL, Esq., of Hinderton, near Chester, was made by
Messrs. Troughton and Simms. The object glass was 2|- inches aperture
and 31 inches focal length. The Y's were supported by short stone piers,
which stood upon a stone slab forming the top of a substantial brick pier,

HH 2

238 TRANSIT OF VENUS, 1874. WAIMEA.

founded on a bed of hard red clay, six feet below the surface of the ground.
It was protected by a small hut, which was almost entirely removed during
observation.

The reticule consisted of five fixed wires of cobweb and one movable by a
micrometer screw, besides the usual pair of horizontal wires to define the
middle of the field. The value of a revolution of the micrometer screw was
found from a great number of observations of Polaris to be 65" '52. The
revolutions of the screw were numbered in the observing books with
increasing readings towards the head. "When the movable wire coincided
with the center wire, the reading was —

r

10-043 on December 6,
10*045 on December i5,
10*046 on December 20.

The reading 10r<043 has been used throughout the reductions.
The Equatorial intervals of the wires were found by means of the movable
wire and the known value of the micrometer screw as follows : —

//

a + 399-94
b + 203-67

C O'OO

d — 201 '08
e — 3g6'2o

When the micrometer head was on the east side of the telescope, equatorial
stars transited the wires in the order above.

The Level Error (Table I.) was found by means of a striding spirit-level.
The original glass bubble of the level was accidentally broken at Honolulu,
and it was replaced by a spare bubble intended for the Altazimuth. The
value of the divisions was determined by attaching the glass bubble to the
telescope of the Altazimuth.

1874. October 20, 21-26 divisions were found equivalent to 70" -3o; idiv- = 3"'3i

ii -io „ „ „ 37"'4o; „ 3"-37

October 21, 18-45 „ „ „ 62"'oo; „ 3"-36

16-70 „ „ „ 58"'43; „ 3"-49

16-00 „ „ „ 55"'47; „ 3"'48

24-26 „ „ „ 77"- 18; „ 3"' 1 8

November 6, 19-80 „ „ „ 66"'77; „ 3"-32

MERIDIONAL OBSERVATIONS. 239

The mean value 3" • 36 was adopted. Mr. Johnson had considerable trouble
with this striding level, as it was continually requiring to be adjusted. For
this reason the level was not applied quite as often as was desirable. It was
Mr. Johnson's habit to apply the level, in both positions of the transit
instrument, on the finish of his night's work. Although the piers were of
stone, the illuminating lamp seems to have disturbed the level error. The
"clock slow" obtained from stars with lamp E. is generally greater than
with lamp "W. Mr. Johnson always observed clock stars with both positions
of the instrument.

The correction to the level error for inequality of the pivots was found by
repeated levellings to be — 0"'42 (micrometer E.).

The Error of Collimation of the fixed center wire of the transit was obtained
from observations of close circumpolar stars with reversed positions of the
transit axis. All such observations were transits over the movable wire, and
the error of collimation of the center fixed wire is obtained from them by
assuming that it coincided with the movable wire when the micrometer
reading was I0r>043. The individual determinations are given in Table II.

The Error of Azimuth was obtained in the usual manner from the obser-
vations of close circumpolar stars combined with those of clock stars. The
errors are given in Table III. There is no mention made of the adjustments
having been altered between the observations of December 3 and December 4.

TRANSITS of STARS observed at WAIMEA (Table IV.).

The places of the stars Bradley 95, 402, 3147, 3187, Groombridge 642,
750, and Lalande (Fed.) 693 have been brought up from the Greenwich new
7-year and 9-year Catalogues for 1864 and 1872. The constants for com-
puting the apparent places were extrapolated for 1875 '0 from those contained
in the annual volumes of the Greenwich Observations.

For complete transits, the mean observed time of transit by chronometer N
over the five wires was reduced to the center wire by applying the correction

i5 Sin NPD additive when the micrometer-head was east. For imperfect
transits, each wire was reduced to the center wire by means of the intervals
given on page 238. "When only one side wire has been observed, the time
recorded is given at the foot of the page. The level error proper for the
position of the transit axis, as given in Table I., has been used, taking the
mean where it has been observed more than once. The value of the Colli-

240 TRANSIT OF VENUS, 1874. WAIMEA.

mation Error used throughout is 3" '65, positive with micrometer west. There
are a few days when, strictly speaking, a smaller value ought to have been
employed, but the fact has no importance, as Mr. Johnson was careful to
observe time-stars with both positions of the instrument. The observations
of close circumpolar stars were made with the micrometer wire ; the wire was
moved successively by quantities equal to one-half or one-quarter of a revo-
lution of the screw, and the star then allowed to transit. With Polaris it was
Mr. Johnson's habit to record the time when the star's disk seemed to be just
touching the wire on both sides. The successive intervals, corresponding to
the instants of bisection of the star's disk thus obtained, are not so accordant
as those obtained by other observers by the method of estimating the instant
of bisection. The number of observations of the circumpolar star, counting
the two contacts as one, is shown by a number following the mean micro-
meter reading thus "Polaris 8r>750 (8)." The observations with the two
positions of the transit axis have been separately reduced. On the days
referred to above, when a different collimation error should have been
employed, they, of course, appear discordant.

The star's apparent R.A. includes the effect of diurnal aberration.

The transits selected for publication are those on which depend the
difference of Longitude with Honolulu and the Local Time for the Transit
of Venus.

APPROXIMATE LATITUDE of WAIMEA.

The approximate latitude depends upon the meridian altitudes of the Sun's
upper limb, as observed, on 22 days in November and December 1874, by
Lieutenant Wellings, with an ordinary navigator's sextant by Whitbread, and
mercurial horizon. The Index error of the sextant was determined in the
usual way by observing the diameter of the Sun " on " and " off" the arc.
The mean instrumental diameter of the Sun was 4" greater than the tabular
diameter. No mention is made of the other errors of the sextant, or of the
dark glasses employed. The mean of Lieutenant Wellings' observations gives
the latitude —

21°. 57'-2N.,

which is probably within one minute of the truth.

LONGITUDE of WAIMEA.

The determination of the difference of longitude between Mr. Johnson's
station and that at Apua, Honolulu, has been described in detail in the

JOHNSON'S OBSERVATIONS OF INGRESS.

241

preceding pages. The transit instrument at "VVaimea was found to be
7m. 13s-48 "West of the transit instrument at Honolulu. Assuming the
longitude of Honolulu to be 10h. 31m. 26s-3 ± 2s, the longitude of Waimea
is 10h. 38m. 39s-8 ± 2s West of Greenwich.

REPORT of MR. R. JOHNSON on his OBSERVATION of the INGRESS of VENUS,

1874, December 8.

On 1874, December 7, H.M.S. Reindeer arrived and anchored to the east of
Waimea river. Arrangements were made with Captain ANSON, her Com-
mander, for the protection of the observatory ground against intrusion on
December 8, and that Nav. Sub-Lieut. WARLEIGH should assist the Rev.
Mr. Dunn during the transit.

A tent was pitched outside the observatory inclosure to cover Mr. Dunn's
telescope, so that any confusion arising from our respective orders might be
avoided.

On December 8, everything being in good order and the chronometers
compared, the sentries were posted in due time and in proper places. This
precaution, however, was scarcely necessary, as I had the grounds " tabooed,"
or, as they call it, " kapu/' for the day.

Mr. Wellings and I took up our posts about 15 minutes before the time of
expected external contact.

Twelve minutes before internal contact the entire disk of Venus was dis-
tinctly visible, a faint ring of light beginning to appear round the edge off
the Sun. Four minutes and a half later the ring of light was very plain. No
black drop like that which we see in the model appeared at all.

The cusps had not the sharpness they often have in the model on a good
day. The weather was beautiful, not the faintest cloud or mist appeared.

Time by Sidereal
Chronometer N.

At 20. 35. 0
20. 39. 30
20. 44. 55
20. 46. 34

whole disk of Venus completely visible.

ring of light complete.

ring of light.

notice to Lieut. Wellings to attend carefully.

20. 46. 53 •o{inde2Slignt} beginning to appear to meet.

20. 47. 2'3 meeting of cusps appeared to take place, and light
clearing.

242 TRANSIT OF VENUS, 1874. WAIMEA.

Time by Sidereal
Chronometer N.

h ra s

At 20. 47. 7 '2 a distinct band of light between edge of Venus and

Sun's limb.
20. 47. 15-4 Venus well on the Sun's disk.

No Uaclc drop appeared. When internal contact was very near, the
brownish smoke-like colour between the edge of Venus and the Sun began
to clear off.

At 20h. 35m. 0s the entire disk of Venus was perfectly visible, the part
outside the Sun having a faint ring of light round it, except at the western
edge. The light was visible round it about two-thirds of the extent of
Venus outside the Sun. At 20\ 39m. 30s. the ring of light was complete.

I am inclined to think the actual contact took place between 20h. 46m. 53S>0
and 20h. 47m. 2s-3, the light appearing to break through at the first time, and
certainly at the last.

At 20h. 46m. 53S>0 light flashed for an instant between the edge of Venus
and the Sun's limb, but immediately disappeared. It was as if the cusps met
in a flash.

At 20h. 47m. 2"'3 the cusps most certainly met, and after that the light
between the edge of Venus and the Sun's limb continued to widen until
20h. 47m. 7S>2, when the band of light between the edge of Venus and the
Sun's limb was very distinct. The reason I am inclined to put the contact
a little before 20h. 47m. 2S>3 is in consequence of the flash of light before
mentioned, and the short time which elapsed before Venus was well on
the Sun.

Ordinarily in the model, one sees a dark (black) band between Venus and
the Sun's limb just before contact, and the light breaks through this band.
In the actual transit, as I observed it, no llack band appeared, but in place
of that a smoke-coloured darkness, through which it was much more difficult
to discern the breaking through of light, or in other words the meeting of
the cusps.

About 7m. 32s-3 before the actual contact, the light of the Sun crept round
the outside edge of Venus, which, though very faint, was distinctly visible.
Mr. Wellings observed it as well as myself, as I called his attention to it so
that there should be no mistake about it. This light continued till very near
contact, when it became excessively faint, and the smoke-like appearance I
have measured took its place.

DUNN'S OBSERVATIONS OP INGRESS. 243

All the times recorded refer to the internal contact at Ingress. I observed
the external contact, but not, I think, with sufficient accuracy to allow me to
record it. Moreover, I did not like to take the time of external contact, lest
I should be biassed by the calculated interval between the external and
internal contacts.

There was scarcely any appreciable " boiling " of the Sun's limb.

The observing telescope was mounted on a solid wooden post within the
inclosure, but sufficiently far from the fence to prevent the heated air
streaming from the top of the fence producing, by its changeable refraction,
any unsteadiness in the view. The power used was a Hughenian eye-piece
of 130.

R. JOHNSON.

The telescope used by Mr. Johnson was an achromatic by Dollond of
3|- inches aperture and 46 inches focal length, of excellent definition. It was
fitted by Messrs. Troughton and Simms with a solar diagonal reflector. Dark
glasses screwed on at the eye-end. It had a steady but simple kind of
equatorial mounting, attached to the top of a heavy baulk of timber sunk
several feet in the ground, and was used in the open air. There was a slow-
motion screw in Right Ascension with a convenient handle.

MR. R. DUNN'S OBSERVATION.

The Reverend Robert Dunn, of Honolulu, having expressed his intention
of visiting Waimea about the epoch of the Transit of Venus, there was placed
at his service an achromatic by Dollond, belonging to the Royal Observatory,
Greenwich, of 2'7 inches aperture and 33 inches focal length, fitted with a
solar diagonal reflector, negative eye-pieces of powers 67 and 134, and a
neutral tint achromatised wedge. The telescope was mounted upon a firm
tripod stand, with altazimuth movements and steadying rods of the usual
construction ; but, in consequence of the shortness of the tube between the
eye-end and the principal point of support, and the absence of mechanism
for giving slow motion, it was difficult to follow the diurnal motion, especially
with the higher power.

Mr. Dunn practised for several days with the model at Honolulu. Such
observations could be made with this small instrument quite as accurately as
with the larger ones, with the power 134, but not with the lower power.

i i

2M TRANSIT OF VENUS, 1874. WAIMEA.

At Waimea, Mr. Dunn's station was 60 yards N.E. of Mr. Johnson's. The
time of his observation was recorded, from the Solar chronometer L, by
Sub-Lieut. Warleigh, of H.M.S. Reindeer. He made use of the power 67.

Mr. Dunn writes : —

" Before internal contact, J or ^ of the planet being still off the Sun's disk,
I saw light all round the planet. My impression was that I was deceiving
myself, through wishing to see the whole disk, but I failed in endeavouring
not to see this ring of light. When I say % or | of the planet not being yet
on the Sun's disk, I mean some considerable interval before the internal
contact. I have not experience enough to judge such things, and I did not
mark the time. As the moment of contact approached, a sort of misty,
smoky, or woolly cloud seemed to be where we looked for the black drop.
The time recorded [3h. 39m. 1JS] was when I was sure of sharp clear light
between the planet and the outer limb of the Sun. The instrument was
unsteady through the wind, blowing sharply from S.W., just about the time
of contact, and my own impression was that I was decidedly late. .

" Having to leave Waimea an hour after the contact was observed,
Mr. Johnson undertook the comparison of chronometers, &c.

" 1874, December 10. R. DUNN."

For Mr. Johnson's observation of internal contact we have —

h m s h m s

Recorded times by the f 20. 46. 53 • o 1 M . 2Q_ 6> 5 g

Sidereal chronometer N |_ 20. 47. 2 '3 J

Adopted Correction of N (Table VI.) — 7. 36 • 47

Local Sidereal Time - - 20. 3g. 21 • 18

Assumed Longitude West - 10. 38. 3g'8o

Gieenwich Sidereal Time - 7.18. 0-98

Local Tabular Distance of Centers - i5'. 3;" '56

Whence the following final equation, assuming, as before —

R = 976"'8o, r = 3i"'42,

7"- 82 = — o"-228o n +-6535 8 R.A. — 7o58 8 N.P.D. — o"-o34O 8 t — S R + 8 r.

For Mr. Dunn's observation we have —

h m a

Recorded time by Solar chronometer L 3. 3g. i • 26

Correction of L (Table VIII.) - —9. 58 -47

Local Mean Solar Time - 3. 29. 2-78

Local Sidereal Time - - 20.39.39-69

G. L. T.

ADJUSTMENTS OF THE TRANSIT INSTRUMENT.

245

TABLE I. — LEVEL ERROR of the TRANSIT INSTRUMENT.

[The sign — indicates that the East Pivot is high.]

Sidereal

Micro-

Level Error

Sidereal

Micro-

Level Error

Time of

meter

corrected for

Time of

meter

corrected for

Day.

Level

E or

Inequality

Day.

Level

Eor

Inequality

Determination.

VV.

of Pivots.

Determination.

W.

of Pivots.

1874.

h m

//

1874-

h ra

//

December 2

3. 5o

E

- 4-18

December 12

6. 35

W

- 3-6i

3.55

w

- 5-54

6. 40

E

- *'94

i 3. 10

E

- 3-04

'4

3. i5

W

- 3-44

3

3.4o

E

- 3-78

3.20

E

- 2-94

3.45

W

— 4^62

i5

23.40

E

— 2'01

3. 5o

E

- 2-27

3. i5

E

- 3'6i

3.25

W

- 2-37

4

4.40

E

- 3'44

4.42

W

- 5-12

it

3. 5o

E

- 2-18

4.48

W

- 3'85

3. 55

W

- 3-io

4. 5o

E

- 3-28

14.40

E

— 2' IO

'7

i. 20

E

- 3-44

5

4.25

W

- 3-6i

18

3. i5

W

- 2-43

4. 3o

E

- i-93

3.20

E

- 1-76

4.35

E

- 3-34

19

3.25

E

- i-43

4.40

W

- 4-78

3. 3o

W

- 3-n

6

2. 10

W

- 4'7«

21

2. So

E

- 2-27

2. 15

E

- 4'°4

2. 55

W

- 2'77

2. 2O

W

- 3-95

2.25

E

- 3-n

22

2. 2O

E

— 2'IO

2.25

W

- 3-6i

7

2.25

W

- 4'U

2. 30

E

- »' 77

24

3. 0

W

- 3-27

2.35

E

- 3-7o

3. 5

E

- 2-52

2. 40

W

- 5-29

I875.

6. 35

E

- 3-53

January 2

4. 5

E

— O'42

4. to

W

-"1-76

X

2. 40

E

- 3-5i

2.45

W

- 5-46

4

2. 2O

W

- 1-26

2.25

E

+ I '40

9

3. 40

E

- 3-70

3.45

W

- 4-02

5

6. 5o

W

- 0-17

6. 55

E

+ o-25

10

2. 10

W

- 3-6i

10

6. 10

E

+ O'O2

2. 15

E

— 2-84

6. 20

w

— o-Sg

ii

2. 2O

W

- 3-85

12

7-25

E

+ 0-93

2.25

E

— 2' IO

7. 3o

W

+ 2-43

ii 2

246

TRANSIT OF VENUS, 1874. WAIMEA.

TABLE II. — ERROR of COLLIMATION of the TRANSIT INSTRUMENT.

[The sign is considered Positive when it implies an additive correction to the time of observed transits of Stars above the
Pole with the Micrometer West.]

Day.

Object.

Error of
Collimation
of Center
Wire.

Day.

Object.

Error of
Collimation
of Center

Wire.

1874.
December z

3

4
5
6

7

8

9
10
ii

12

n
+ 2'8

2-5
3'4
4'5
2'4
3-o
3-o

2'5

3-i

4-8
4-0
4-0
5-7
3'7
5-o
4'5
3-5
4-6
+ 4-3

1874.
December i3

H

i5
16
18

'9

20

ZI

22
24

i875.
January 2

4
5

10
12

//

+ 3-i

3-5
3-7
4'5
4-0
4-8
3-3
3'4
3-7
i'8
1-7

2' I
I-9

3-4
3-7
1-9

+ I'?

Polaris

Lalande (Fed.) 698

Cephci (Hev.) 5i

Polaris

& Ursa; Minoris S.P

5 Ursa; Minoris S P

TABLE III. — AZIMUTH ERROR of the TRANSIT INSTRUMENT.
[The sign + denotes that the East Pivot was too far North.]

Apparent Adopted
Day. Stars. Error of Error of
Azimuth. Azimuth.

Apparent Adopted
Day. Stars. Error of Error of
Azimuth. Azimuth.

1874.
Dec. z Brad!

Brad!
Polar
3 Brad!
Polar
Groo
4 Polar
5 Polar
6

cy 3147 and K Fiscium. —
ey 95 and a Eridani ... —

/ //

••• 1

9 i f-9'4

9'9 J
••7 |
7'9 f- t'l

7'4 J
1-3 +1-3
z-4 +2-4

2-2 +2-3

1874.
Dec. 7 Polar

Lalan
SUrs
8 BradI
«Ursi
9 Polar

1° ,,

"
iz Grooi

/ //

ri -,

i'9 > + 1'6
i-o J

1-8 •,
^+2-7
i-i J

5-2 +5-2

3-9 +3-9

}.-5 +4-7
^.•6 +4'3

de (Fed.) 69 3 and J' Ceti +
K Min. S.P. and i Gem. +
ey 402 and o Eridani . . +
B Min. S.P. and i Gem. +
s and a Eridani ... . +

ey 95 and 20 Ceti —

mb. 642 and a Eridani . -

,, +

nbridge 7 5o and a Tauri +

ADJUSTMENTS OF THE TRANSIT INSTRUMENT.

Table III. — Azimuth Error of the Transit Instrument — continued.

247

Day.

Stars.

Apparent
Error of
Azimuth.

Adopted
Error of
Azimuth.

Day.

Stars.

Apparent
Error of

Azimuth.

Adopted
Error of
Azimuth

1874.
Dec. 12.

i3

H
i5
16

17
18

19

21

8 Ursa; Min. S.P. and i Gem.
Polaris and a Eridani

+ 4-1
+ 3-2
+ 8-2
+ 4-6
+ 4-8
+ 7-5
+ 7-3
+ 7-1
+ 7'4

+ 4-3
+ 3-2
+ 8-2

+ 4-4
+ 4-8
+ 7-5
+ 7-3
+ 7-1
+ 7-1

1874-
Dec. 22

24

1875.
Jan. 2

4

5

10

12

Polaris and o Eridani

> > > >

Ccphei (Hev.) 5i and e Canis

Polaris and o Eridani

S Ursa: Min. S.P. and yOrionis
A. Ursie Min . S. P. and o Orionis
S Ursse Min. S.P. and y Gem.

+ 6-9
+ 6-8

+ 4-1

+ 9-3
+ 9-8

+ 5-2
+ 3-9
+ 8-4

+ 6'9

} + !,

+ 9-4
+ 9-8
+ 5-o
+ 3-9
+ 8-3

TABLE IV. — TRANSITS of STARS observed at WAIMEA by Mr. R. JOHNSON.

Day.

Object observed

and
(Number of Wires).

Mean observed Time

by Chronometer N

of Transit over

the Center Wire.

Seconds of

True Transit

over the

Meridian.

Seconds of

Star's
Assumed
Apparent

R.A.

Chronometer N

apparently

Slow.

1874.
December

7 E 7 Pegasi

44 Piscium

12 Ceti

e Andromeda; ,

o Cassiopeia? (4) ,

Ceti

S Piscium

20 Ceti

fi. Andromeda;

Piscium

Polaris, 9-250 (5)

W ,, 9-2So(5)

a Eridani

o Piscium

Arietis

0 Arietis

{' Ceti

67 Ceti

E Lai. (F.) 693, 7-600 (5).
W „ 7-600 (5).

(8 Tauri

5 Orionis

1 Geminorum

o. 14.

o. 26.
o.36.
o. 3g.
o. 41.

0.44.
0.49.

0. 54.

0.57.

1. 4.

i. 18.

1.23.

i. 40.

1. 46.
j.55.

2. 7.
2. I4.
2.18.
4.53.
4-57.
5.26.

5.33.
6. 4.

26-43
38-o6
18-14
35-25

3-68
57-37
50-24
15-62
27-39
1 5- 70
38-10

6 -20
42-36
25-42
21-93
45-67

0-48
22-90
13-90
58-zo

i-43
14-98

9-53

25-97
37-66
17-76

34-71

2-73

57-02

49-81

lS'22
26-78

i5-27
46-91

40-46

42-91

25-38
21-86
45-59

0-44
22-91
33-44
32-86

i-35

'4'97
9-45

}

47-57
59-44
39-35
56-8i
24-84
18-92
n-65
37-o5
48-78
27-33

3-98

5-i9
47-73
44-25

7-87
22-81
45-3i

24-16
37-96
3i-98

7. 38-40
7. 38-22
7. 38-4i
7. 37-91
7.37-89
7. 38-10
7.38-16
7-38-17
7. 38-oo
7.37-94

7- 39-70

7- 37 '7*
7-37-65
7.37-61
7.37-72
7-37-63
7. 37-60

7. 37-72

7- 37-I9
7- 37-oi

248

TRANSIT OF VENUS, 1874. WAIMEA.

Table IV. — Transits of Stars — continued.

Day.

Object observed

and
(Number of Wires).

Mean observed Time

by Chronometer N

of Transit over

the Center Wire.

Seconds of

True Transit

over the

Meridian.

Seconds of

Star's

Assumed

Apparent

R.A.

Chronometer N

apparent'y

Slow.

1874.
December 7 E 8 Ursae Min. S.P., 14-000 (5)

W ,, 14-000(5)
Canopus (4)

8 E r) Piscium

a Kridani

o Piscium

ft Arietis

0 Arietis

11 Ceti

67 Ceti

12 Ceti

v Ceti

Bradley 402, 8-000 (5).

W ,, 8-ooo(5).

1 Geminorum

v Orionis

E 5 Ursa: Min. S.P., 12-000 (5)
W ,, i2-ooo(5)

9 E Polaris, 9- 25o (5)
W ,, 9-25o (5)

a Eridani

67 Ceti

I2 Ceti

S Ceti

•X2 Ceti

a Arietis

E € Arietis

a Ceti

T Arietis . .
o Tauri . . .
/Tauri ...
e Eridani . .

10 E 44 Piscium

12 Ceti

f Andromeda! .

0 Ceti

5 Piscium ....

20 Ceti

H Andromeda; .
f Piscium

6. 14. 59-40
6. 24. Sz'oo
6. 29. 49-01

1.32.

i. 40.
i. 46.

1. 55.

2. 7.

2. I 3.
2.18.
2.29.

2.36.

3. 9-
3. 12.
6. 4.
6. 8.
6.17.

6. 22.

24-29
41-40
24-30

20-81
44-35
59-04
21-68

7-54
55-62
19-50
J7'3o

7'97

2-71

25-3o

21-80

1. 18. 41-10

1.23. 6'80

1.40. 37-54

2. 1 8. 18-68
2.29. 4-52
2.40. 38-42
z. 44. 23 -16

2.52. 9-29

2.59.38-53

3. 3. 19-42
3.2I.35-43
3. 25. 40-00
3.2i. 33-13

3.34.37-25

0.26. 31-82
o. 3i. 11-84
o. 40. 29-23
0.44. Si* 19
0.49.44-04
o. 54. 9-56

0. Sj. 21-27

1. 3.59-84

58-37
59-19
49-43

23-82
41-19
23-86
20- 3i
43-84
58-6i

21-32
7'II
55-19
46-77
43-9I

7-83

2-60

57-93

58-07

40-00
3a-5o
38-54
i8-85

4-58
38-54
23-26

9'3o
38-02
19-05
34-92
39-59
32-69
36-98

3i-49
n-55
28-70
50-96
43-69
9-26
20-64
59-49

20-77
12-33

47-75

5-i6

47-72

44-24

7-87

22-80

45-3:

31-14

19-22

9'94

32-oo
26-76

20-53

2'73

5-i3
45 -3o
3i-i3

5-oi
49-85

4-38
45-22

1-16

5-8o
58-89

3-i9

59-41
39-32

56-77
18-90
11-62

37-02
48-74

7. 38-01
7. 37-10

7. 36-07
7.36-o3
7. 36-14
7. 36-07
7-35-97
7. 35-8i
7. 36-01
7.35-97
7-35-97

7.35-40

7.35-83
7. 35. 84

7. 37-47

7.33-5o

7.33-4I
7. 33-55
7.33-45
7.33-53
7.33-41

7.33-64
7.33-83
7.33-76
7-33-79
7. 33-8o
7.33-79

7. 32-o8
7.32-23
7- 3i-93
7. 32-o6
7.32-07
7.32-24
7.31-90
7. 32-i8

MERIDIONAL TRANSITS.

Table IV. — Transits of Stars — continued.

249

Day.

Object observed

and
(Number of Wires).

Mean observed Time

by Chronometer N

of Transit over

the Center Wire.

Seconds of

True Transit

over the

Meridian.

Seconds of

Star's

Assumed

Apparent

R.A.

Chronometer N

apparently

Slow.

1874.
December

10 E Polaris, 9-250 (5)

,, 9-a5o(5).
o Eridani ,
o Piscium
(3 Arietis .
a Arietis .

1 5 E e Piscium

Polaris, 8-625 (8) ,
,, 8-5oo(8),
W a Eridani .

o Pincium

/8 Arietis .

a Arietis .
E 7= Ceti .

<r Arietis .

€ Arietis .

o Ceti

8 Arietis .

r1 Arietis.

1 6 E e Piscium.

Polaris, 8-875 (8)
W ,, 8-750(8;

a Eridani

5 Arietis

T" Arietis

o Tauri

/Tauri.

Eridani .
E 8 Eridaui ,

•n Tauri . ,

17 E Polaris, 11-750 (i)

a Eridani

1 8 E Polaris, 9-000 (7)
W ,, 8'875(8)

a Eridani

o Piscium

1. 18. 32-8o
1.23. 1-90
1.40. 35-82
1.46. 19-14

1.55. i5-67

2. 8.39-37

i. 3.
1.16.

1.25.

1. 40.
1.46.
i.55.

2. 7.
2.44.

2. 5l.
2.59.

3. 3.
3. 10.

3.21.

47-10
21-63

3-6i
23-06

6-69

3-37
26-91

9-56
55-73
24-15

4-86
49-11

2O'OI

I. 3.44-72

1.17. 3-25
i. 24. 17-28
1.40. 20-68
3. 11.46-13

3.21. I7'83

3.25.22-35
3. 3i. 15-55
3.34. 19-71
3.44.33-49

3.47.21-17

1.26. o-5o
i. 40. 19-16

i. 17. 27-93
i.i3. 5o'94
1.40. 14-25
1-45.58-32

35-85
3i-25
36-68
19-21
15-66

46-76
19-11
14-10
24-01

6-86

3-46
26-98

9-24
55-33
23-70

4-53
48-67

20-10

14-38
12-43
21-66
46-19
17-88
22-47
i5-65
19-95
33-29
20-73

10-91
I9-55

9-90

3-5o

15-52

58 -So

1-98

5-u

47-7I

44-23

7-86

27-27
57-82

4-96
47-68
44-18

7-83
49-84
35-87

4-37
45-23
29-40

I'll

27-26

} «,

29-40
I'll

5-8i
58-91

3-i9
16-36

3-9I

56-25
4-91

55-52

4-89
47-66

- 7-31-67

7.3i-57
7. 3i-5o
7. 3i-43
7. 3i-5i

7.I9-49
7- 18-79

7.19-05
7. 19-18
7. 19-28
7- '9''5
7. 19-40
7. 19-46
7.I9-33
7.i9-3o
7. 19-27
7. i8-93

7.17-46

7. 16-72

7- l6'79
7. 16-71
7. 16-66
7.16-74
7. 16-76
7. 16-93
7. 16-82

7. 14-66
7. 14-64

7. 10-75

7. io-63
7. 10-84

250

TRANSIT OF VENUS, 1874. WAIMEA.

Table IV. — Transits of Stars — continued.

Day.

Object observed

and
(Number of Wires).

Mean observed Time

by Chronometer N

of Transit over

the Center Wire.

Seconds of

True Transit

over the

Meridian.

Seconds of

Star's

Assumed

Apparent

R,A.

Chronometer N

apparently

Slow.

1874.
December 18 W $ Arietis

8 Arietis .
E 8 Eridani .
T; Tauri . . .
7' Eridani
37 Tauri .

19 E M Andromeda! .

e Piscium

Polaris, 8-875 (8)
W „ 8-75o(8)

a Eridani

fCeti

v Ceti

8 Ceti

•y2 Ceti

a Arietis

E e Arietis
sCeti.
8 Arietis
T' Arietis

21 E yu Andromeda! .
e Piscium
Polaris, 9-125 (6)
W ,, 9-000(7)

o Eridani .

Ceti.
8 Ceti.
72 Ceti . .
E 8 Arietis
r1 Arietis

0 Tauri
/Tauri

1 Eridani .
8 Eridani .
•n Tauri

a Aurigse.

1.54.54-85
3. ii. 39-79

3. 44. 27-30
3. 47. iS'og

3. 59.23-73

4. 5. 30-29

0. 56.

1. 3.
i. 16.
1.24.

1. 40.
2.28.
2.36.

2. 40.
2. 43.

2. 5l.
2.59.

3. 2.

3. n.

3.21.

0. 56.

1. 3.
1. 17.

1.23.

1. 40.

2.36.

2. 40.
2.43.

3. ii.

3.21.

3.25.

3. 3i.
3.34.
3.44.
3.47.
5.14.

58-28
36-36
55-69
14-28
n-gS
39-48
27-38
13-32
58-24
44'i5

38-27
9-97

54-48
32-54
38-25
20- 14
8-21
23-72

9-40

54-34
34-57

6-29
10-88

4-o5

8-04
21*26

9-i5
34-08

54-95
39-89
27-20
14-68
23-66
29-90

57-72
36-i3

i-75
3-5o

l3'20

39-63
27-55
i3-54
58-43
44-25
13-04
53-73
37-92
9-61

53-85
32-26
55-87
55-76

9-48
23-93

9-64
54-56
34-16

5-87
io-58

3-7o

7-90

2I'l3

8-70

33-25

44-18
29-40
i6-36
3-9i
12-66
19-01

48 -63

27-23

53-57

4-85
31-09
19-18

4-98
49-82
35-86

4'37
45-22
29-40

1-16

48-60
27-21

5i-8o

4-80
19-17

4-98
49-81
29-39

I'll

5-8o
58-90

3-i7
i6-35

3-9i
28 -5o

- 7. 10-77
7- 10-49
7. 10-84

7- i°'77
7. 1 1 - oo
7. 10-89

7- 9'°9

7. 8-90

7. 9-o5

7. 8-35

7. 8-54

7. 8-37

7. 8-56

7. 8-61

7. 8-39

7. 8-67

7. 8-5i

7. 8-52

7. 8-45

7. 5-25

7. 5-o5

7. 4-02

7. 4-68

7. 4-76

7. 4-66

7- 4'?5

7- 4' 77

7- 4'7'

7. 4-78

7. 4-80

7. 4-73

7. 4-78

7- 4'79

7- 4'75

MERIDIONAL TRANSITS.

Table IV. — Transits of Stars — continued.

251

Day.

Micrometer
Eor W.

Object observed
and
(Number of Wires).

Mean observed Time
by Chronometer N
of Transit over
the Center Wire.

Seconds of
True Transit
over the
Meridian.

Seconds of
Star's
Assumed
Apparent
R.A.

Chronometer J
apparently
Slow.

1874.

E

h in s

i. 3. 3i -02

30-76

27-20

- 7. 3-56

Polaris, 8-875 (8)

1. 16. 45- 13

5o*8o

W

,, 8-750(9)

I. 24.. 12* 80

1-25

5i-8o

7. 4-22

I. 40. 7*27

8-49

4-77

7- 3-72

i. 45. 5i -02

5l'I2

47*63

7- 3'49

I. 54. 4.7*4.0

47* Si

44'i3

7. 3-38

E

2. 7. 1 1 '4!

10*08

7-78

7. 3*20

{i Ceti

2. 13.26-36

26*08

22-73

7. 3*35

67 Ceti

2. 17.48-86

48*71

45-23

7. 3*38

24

E

I. 17. 48-30

48*07

1

W

Q*I25 (6) . .

I. 22. 56- 17

59*82

| 49'7°

7- 4'64

I. 31.48-21

48*28

47-63

7. 0-66

1.40. 4- 23

5*23

4'7J

7. 0-52

I. 45.48-20

48*29

47-62

7. 0*67

I. 54.44-87

H'91

44*i3

7- 0-78

2. 7. 8-45

8*46

7-76

7. 0-70

67 Ceti

2. 17.45*66

45*87

45*21

7. o'66

E

£2 ceti

2.29. 31-84

3i'5z

31-07

7- °'45

v Ceti

2. 36. 20- 16

19*85

I9*i5

7- 0-70

5 Ceti

2.40. 5-82

5-54

4*95

7. 0-59

yz Ceti

2.43. 50-77

50*46

49*80

7. 0*66

2. 51.36-89

36*5o

35*84

7. 0*66

2.59. 5-33

4*89

4-35

7- 0-54

Cephei 5i, 8'y5o (4) .

6. 46. 54-37

38-67

1

W

8'7So (A') .

6. So. 42-75

4.2*4.3

| 41*04

6.59-Si

7. o. 44- 3o

/\ n • 77,

43*91

7. 0*81

i875.
January 5

E

6. 7. o-83

0*62

27-11

6.33*5i

W
E
W

8 Ursa Min. S.P., 7- 5oo (7) . .
,, 7'5oo (7) ..

6. 1 5. 42- 14
6. 21.49-10
fi, ij, 4/1 *fi*

50*92
50-91
45-55

j 18*16
12*58

6.32*75
6. 32-97

6.37. 3-6i

3-88

3o'43

6. 33*45

6. 4.6. 12 'OQ

12*55

39*37

6.33'iS

10

E

5. 6. 37*4.0

37*4.1

n*z5

6.26*16

5 i3 55-02

?A* ?A

28*61

6.25*93

£ Tauri

5O*26

6.25*8o

38*23

6. 25-82

a Columbse (3)

5 41 34*80

3J..76

8*81

6.25-95

5 54 5i-38

25*28

6 2 58-59

58-3i

32 *4O

— 6. 25-91

K K

252

TRANSIT OF VENUS, 1874. WAIMEA.

Table IV. — Transits of Stars— concluded.

Pay.

Micrometer
E or W.

Object observed
and
(Number of Wires).

Mean observed Time
by Chronometer N
of Transit over
the Center Wire.

Seconds of
True Transit
over the
Meridian.

Seconds of
Star's
Assumed
Apparent

Chronometer N
apparently
Slow.

R.A.

1875.
January i o

12

E

W

E
W

\ Urs

i Gen
v Orio
SUrss

a Arg
y Gen:
Sirius
9 Cani
f Cani
£ Gem
5i Ge
5 Gem

BMin. S.P., ii-25o(7).
,, ii-25o (7).

h m a
7.49.20-57
7.59. 0-7I

6. 2.55-75
6. 6.5o-23
6. i5. 12-18
6.21. 55-6o
6. 27. 34-42
6.36.53-19
6.46. 1-73
6. 54.46-54
7. o. 6-45
7. 3. 5-6i
7. 12.35-35
7.19- 3-45

•
29- 5o
17-18

55-53
5o"o9
44-38
3g -o5
35-78
53-66
2-48
47-24
7-32
6-06
35-82
3-89

8

} 57-62

32-40
27-15

} '9'i5

12-53
3o-52
39-42

24-08
44-07
42-90
12-78
40-68

- 6.25-72

6.23-i3
6. 22-94

6.22-57

6.23-i5
6. 23- 14
6.23-o6
6.23-16
6.23-25
6.23-16
6. 23-04

- 6.23-21

BMin. S.P., 12-750 (10)
,, 12-750(10)
Is

TABLE V. — COMPARISON of the STATIONARY CHRONOMETERS J, L, and N at WAIMEA.

Day and

Day and

Approximate

Time by

Time by

Time by

Approximate

Time by

Time by

Time by

Local Mean

L (Solar).

J (Sidereal).

N (Sidereal).

Local Mean

L (Solar).

J (Sidereal).

N (Sidereal).

Time.

Time.

1874. h m
Dec. 6, 22. 24

h m t

10. 34. 19-5

h m i
3.42.4I-0

h m s

I874. * «

Dec. 10, 23. 9

li m »

ii. 19. i5-o

h m .

h in s

16. 38. 3o-o

10.37. 8-5

l5.40.40-0

ii.23. o-5

4.47.41-0

• •

7, II. 2

II. II.45-0

. .

4.17. I9-0

II, II. 0

ii. 9.39-5

4. 36. 19-0

..

II. 17. 25'0

4. 27. 55-o

ii. 11.48-5

..

4. 32. 59-0

7, 23. 16

11.26. o-o

4.38.33-0

23. 7

n. 17.34-5

4.46. 17-0

II. 29. 12' 5

..

1 6. 36. 47-0

ii. 19.44-0

16.42. 53-o

8, 2. 0

2. 9.35-5

7.22. 36 -o

..

12, 10. I 8

10. 28. Si -5

• •

3. 53.49-0

2. 12. 28-O

19. 20. 29-0

1 3.

I. 26. 22-5

6. 57.28-0

..

3.47

3.57.32-0

21. 5. 5o-o

1 3, o. o

o. o. 9-5

5.33. 2-0

3. 5g. 20-0

9. 12. 39-0

o. 1.37-0

17. 28. 47-0

9, o. 25

o.35. 2-5

. .

17. 46. 42*0

10.49

10. 59. 54-5

4. 34. 38-o

0.39. Si -5

5. 56. 40-0

n. 1.45-0

• •

4. 3o. 42-0

II. 16

n. 26. 14-0

4. 39. 39-0

23.22

II. 32. I7'5

5. 9. 8-0

11.27.38-5

4.46. 16-0

ii. 34. i6-5

17. 5. 16-0

10, 9. 17

9. 27. 10-0

2.49. 3o-o

14, ii. 5

ii. 15.43-0

4. 54. 32-o

9.32.44-5

••

2.49.45-0

ii. 19. 28-5

• •

4. 52. 22 -O

COMPARISON OF CHRONOMETERS.

Table V. — Comparison of the Stationary Chronometers — -concluded.

253

Day and

Day and

Approximate

Time by

Time by

Time by

Approximate

Time by

Time by

Time by

Local Mean

L (Solar).

J (Sidereal).

N (Sidereal).

Local Mean

L (Solar).

J (Sidereal).

N (Sidereal).

Time.

Time.

1874. h m

h m 1

h m «

h m »

1874. h m

h m B

h m s

h m s

Dec. 14, 23. 24

11.34. °-5

5. 14. 54-0

Dec. 21, 10.42

IO. 52. O'O

4.52. 5-o

ii.37.54-5

17. 12.48-0

10. 55. 14-5

5. 2.18-0

..

i5, 10. 33

10. 43. 48

•o

4. 26. 34-O

..

22.43

10. 53.41-5

..

16. 55.44-0

10. 46. So' S

..

4. 23. 32-o

10. 56. 32-o

5. 5.37-0

..

22. 27

10. 37. 16

•o

16. i5.53-o

22, 22. 45

io.55.23-5

17. I. 21-0

10. 40. 18

•o

4-25. 5"O

. .

io.58.58-5

5. 12. 6-0

. .

l6, II. 22

11.42. 6

•5

5. 29. 5"o

. .

23, 13.41

i. Si. 6-5

8. 6.44-0

. .

ii. 43. 5o

•5

5.24.35-0

i. 53. 32-o

..

8. 1.55-0

22. 5O

II. O. 2

•5

. .

16.42. 37-0

24, 1 3. 14

i. 24. 24-5

7.36.37-0

n. 5.41

•o

4. 54. 35-o

1.28. 7-0

7.47.43-0

..

1875.

17, 10. i

n. ii. i

•o

5. 1.57-0

••

Jan. 4, 23. 44

ii. 54. 54-5

m f

18. Si. 3S-o

II. 12. 52

•o

••

4.57.25-0

ii. 58.25-0

7. 4. 12-0

1 8, Noon

12. 2.47

-o

••

17.49.25-0

5, H.55

o. 5. 1 5-o

f r

7. 3.57-0

1 2. 6. 40

•o

5.59.47-0

••

o. 7. 36-S

7. i5. 26-0

..

IO. 2O

10. 3o. 33

•5

••

4.18.53-0

23.49

n. 59.5i-5

. .

19. o. 3o'o

10. 33. i3

•S

4.28. 6-0

• •

o. 2.14-5

7.12. 4-0

..

22. 5o

ii. o.38

•s

••

16. Si. o-o

9, 22. 18

10.28. i8-S

S. S3. 59-0

..

II. 3. 2

0

5. o. i • o

••

10. 3i. 35-o

t t

17.47. 35-o

19, 9.45

9. 55. 37

o

••

3.47.45-0

10, 1 3. o

I. IO. 2O-5

t ,

8.28.43-0

9. 58. 12

S

3.57. 2-0

• •

i. 12.45-0

8.40. 54-0

22.57

n. 7.32

0

••

17. 1.49-0

23.35

11.45. 17-0

f t

19. 5.23-0

II. II. IO

o

5. 12. i3-o

..

II. 47. 22 -O

7. 17. 18-0

20, 4. 45

4. 54. 55-0

••

22. 5o. 8-0

ii, 4. 3

4.13.35-5

..

23. 34. 25-o

4.59.29-5

n. i. 3i-o

..

4. i5. 32-o

11.46. i3-o

22.54

ii. 4.37

0

••

17. 2.47-0

12, IX. O

o. 9. S6-S

. ,

7-35.57-0

n. 7.25-

S

5. 12. 3o-o

o. 11.45-0

7.47-48-0

••

TABLE VI.— ERRORS and RATES of the SIDEREAL CHRONOMETER N at WAIMEA by OBSERVATION.

Solar Day.

Sidereal Time. ' Chronometer N
Slow.

Loss in the preceding Adopted Losing
24"" Sidereal. Kate.

1874.

h m ma

December 6

I. 10 — 7.39-74

+ 1-57 + 1-72

7

1-59 7-37-8I

1-86 ,-79

8

3.58 7.35-92

1-72 1-07

9

z-44 7.33-62

1-42 2-19

10

i- 12 7. 3i-8o

i-95 1-97

ii

i. 16 7.29-81

1-99 2-42

12

S. 3 - 7.26-51

+ 2-86 + 2-62

K K 2

254 TRANSIT OF VENUS, 1874. WAIMEA.

Table VI.— Errors and Rates of the Sidereal Chronometer N at Waimea by Observation — concluded.

Solar Day.

Sidereal Time.

Chronometer N
Slow.

Loss in the preceding
24h Sidereal.

Adopted Losing
Rate.

1874-5.
December 14

h m

1.38

m e

- 7.22-45

+ 2-02

s

+ 2-56

i5

.2. 18

7. 19-25

3-i3

2-74

16

2.53

7.16-85

2-38

2'5l

18

2.54

7. 10-78

3-39

2-82

19

2. 21

7. 8-58

2-25

2'l5

21

2.41

7. 4-78

1-72

i-56

22

1.44

7. 3-45

i-39

i-39

24

2.33

7. o-65

i-38

i-38

January 2

3.12

6. 38-i5

2-49

i-38

4

1.43

6.35-90*

I'll)

i -80

5

6. i5

6.33-36

2'12

2 -O2

10

5.27

6.25-93t

i- So

I-42

12

6.23

— 6.23-10

+ I-39

+ I-39

* January 4. Transits observed with Micrometer W. only,
f January 10. Transits observed with Micrometer E. only.

TABLE VII. — EEROES and RATES of the SIDEREAL CHRONOMETER J at WAIMEA INFERRED

from TABLES V. and VI.

Approximate Local
Mean Time.

Time by
Chronometer J.

Chronometer J.
Slow on Sidereal Time.

Loss in the preceding
24h Sidereal.

Adopted Losing
Rate.

1874-5. "
December 6, ii-o

b m

4. 6

m R
— 12. 26-2O

- 6-67

- 6-52

7, u-i

4. 28

12. 32-67

6-38

6-45

8, 3-8

21. l3

12. 37-22

6-52

6-5i

9, n-3

4.46

I2.45-72

6-49

6-73

10, 9-2

2.46

12. 52- I I

6-97

6-61

u, 10-9

4.33

12.58-82

6-26

6-16

12, i3-3

6. 57

i3. 5-48

6-07

6-n

i3, 10-8

4.32

i3. ii-oi

6-i5

6-63

14, ii-o

4.5i

i3. 18-23

7-12

6-52

i5, io-5

4.24

1 3. 24-04

5- 3

0

6-24

16, ii-S

5.26

i3. 3o-87

6-55

6-5i

17, ii-o

4.59

13.37-23

6-48

6-28

18, 10-4

4.28

13.43-18

6-08

..:.„ 6'3'

19, 9-8

3.57

13.49- 58

6-53

6-40

21, I0'7

5. 2

14. 2-60

6-37

6-37

22, IO"8

5. 9

14. 9-00

6-37

6-5o

24, i3-3

7.48

14. 23-25

6-75

6-69

January 2, 10-8

5.57

1 5. 20-61

(6-44)

6-61

4, "'9

7- 7

1 5. 34-20

6-65

6-33

5, i»-o

7. i5

i5. 40-41

6-17

6-18

10, i3-o

8.41

1 6. 1 1 -86

(6-22)

6-64

12, 1 2 • O

7-47

— 16.25-24

- 6-Si

- 6-81

COMPARISON OF CHRONOMETERS.

255

TABLE VIII. — EBROES and RATES of the MEAN SOLAR CHRONOMETER L at WAIMEA, INFERRED

from TABLES V. and VI.

Day.

Local Mean Time.

Chronometer L
Slow on Local Mean
Time.

Loss in the preceding
24h Solar.

Adopted Losing
Kate.

1874-5.

h m

m •

.

,

December 6

ii. 7

- 9.58-01

- °'49

— 0-40

7

II. 2

9.58-32

o-3i

0-26

8

3.44

9-58-47

0'22

0-18

9

ii. i3

9. 58 -67

o-i5

0-43

10

9.23

9.59-33

0-71

0-64

II

II. 2

9.59-94

- o-57

— O- 12

12

ii. 16

9. 59 '60

+ 0-34

+ o- 10

i3

10. 52

9. 59-64

— 0-04

- o-45

'4

Ii. 9

10. o-5o

0-86

o*5o

15

10. 37

10. o-63

o-i3

0-29

16

ii. 34

10. I '10

o-45

o-38

i?

ii. 3

10. 1-41

o-3i

0-06

ll

IO. 21

10. 1-22

0-19

O'2O

'9

9.43

10. 1-42

0-20

0-39

21

10. 39

10. 2-92

o-73

o-73

22

10.41

10. 3-53

0-61

0-77

24

i3. ii

10. 5-85

I'M

i-o3

January 2

10.55

10. 12-06

(0-70)

0-99

4

ii. 5o

10. 14- 19

i-o5

0-87

5

n.55

10. 14-97

0-78

o-83

10

i3. o

10.10-40

1-09

I-2I

12

ii. 59

— 10. 22-87

- 1-26

- 1-26

| . -

TRANSIT OF VENUS, 1874.

PART II.

EXPEDITION TO EGYPT,

UNDER

CAPTAIN C. ORDE BROWNE,

*

(LATE ROYAL ARTILLERY).

SECTION I.
OBSERVATIONS ON THE MOKATTAM HILLS, NEAR CAIRO.

With Three Plates.

SECTION II.
LONGITUDE OF ALEXANDRIA.

SECTION III.

OBSERVATIONS AT SUEZ.
With One Plate.

TRANSIT OF VENUS, 1874.

PART II.

EXPEDITION TO EGYPT.

Section 1.

OBSERVATIONS ON THE MOKATTAM HILLS, NEAR CAIRO.

With Three Plates.

TRANSIT OF VENUS, 1874. 259

PAET II.
EXPEDITION TO EGYPT.

SECTION I. — OBSERVATIONS ON THE MOKATTAM HILLS, NEAR CAIRO.

INTRODUCTION.

Page
THE SITE, INSTRUMENTS, AND GEOGRAPHICAL DETERMINATIONS AT MOKATTAM : —

Arrival in Egypt ; Personnel ; Outline of Work 261

The Site at Mokattam 261

The Transit Instrument and Clock 263

Value of a Revolution of the Transit Micrometer Screw. 263

Equatorial Intervals of the Wires 263

Errors of Level, Collimation, and Azimuth 263 and 264

Reduction of the Observed Transits 264

Errors and Rates of the Transit Clock 264

Zenith Distances for Co-latitude 265

LONGITDDE OF MOKATTAM KY GALVANIC SIGNALS :

Preliminary Experiments 266

Routine adopted 268

Method of Signalling 268

Errors and Rates of the Sidereal Standard Clock of the Royal Observatory, Greenwich,

Table 1 269

Errors of the Chronometers employed at Porthcurno on Greenwich Time, Tables II., III.,

IV., and V 270 to 273

Errors of the Chronometer employed at Alexandria on Greenwich Mean Time, Table VI. 274

Explanation of the Mahc-and- Break and Varley Methods of Signalling 276

Adopted Errors of the Transit Clock at Mokattam 276

Errors of the Alexandria Chronometer on Mokattam Mean Time, Tables VII. aud VIII. 277

Longitude of Mokattam from each separate Group of Cable Signals, Table IX. . . . 278
Longitude of Mokattam separately deduced from the Make-and- Break aud from the

Varley Signals, Table X. 281

Collection of Results for Apparent Longitude, Table XI 283

Collection of Resulls for Retardation of the Galvanic Current, Table XII 284

Corrections for Personal Equation 284

Final Longitude of Mokattam 288

L L

260 CONTENTS.

Pago
OliSEKVATlONS OF THE EGRESS OF VENUS, 1874, DECEMBER 8 : —

Report of Captain C. Orde Browne 289

Comparisons of the Clocks employed 294

Observations by Mr. F. M. Newton 295

, , Miss E. M. Newton 296

Discussion of the Micrometric Observations 297

Final Equations resulting from the Observations of Egress at Mokattam 299

Semidiameter of Venus. 302

Time of Internal Contact inferred from the Micrometric Measures of Cusps .... 302

MERIDIONAL AND ALTAZIMUTH OBSERVATIONS IN TABULAR ARRANGEMENT : —

Table XIII.— Level Error of the Transit Instrument 304

Table XIV. — Collimation of the Transit Instrument 306

Table XV. — Azimuth Error of the Transit Instrument 307

Table XVI.— Meridional Transits 307

Table XVII.— Errors and Rates of the Transit Clock 314

Table XVIII. — Errors and Rates of the Altazimuth Clock. 315

Table XIX. — Zenith Distances and Inferred Co-latitude 316

Plate VIII. — Plan of the Environs of Cairo to face 261

Plate IX. — Plan of the Encampment on Mokattam Hills „ 262

Plate X. — Diagrams relating to the Egress of Venus as observed at Mokattam . „ 296

Plate VIII

261

THE EXPEDITION TO EGYPT.

SECTION I. — OBSERVATIONS AT MOKATTAM. NEAR CAIRO.

INTRODUCTION.

SHORTLY after my arrival in Egypt, through the kind offices of General
STANTON, the British Consnl-General, His HIGHNESS the KHEDIVE was graciously
pleased to accord me an interview, at which he expressed his sympathy with
our undertaking, and his desire to further in every possible way the object of
the Expedition. We were afterwards greatly indebted to His Highness for
services which were not confined to such as may be classed under ordinary
assistance — great expense having been incurred by him in providing
transports, guards, and material.

On 1874, October 17, the entire expedition was assembled in CAIRO. Having
with mature consideration selected a site on the Mokattam Hills, an encamp-
ment was formed there on October 21. On October 27 the parties destined
for Thebes took their departure from Cairo, and Mr. Hunter proceeded to
Alexandria.

Our party on the Mokattam Hills consisted of F. M. NEWTON, Esq., Miss
EMILY M. NEWTON, myself, and my wife, with servants, and a guard of Egyptian
soldiers. The work done at the station may be thus summarised : —

Observations for local time were continuous from October 24 to December 21 ;
determinations of co-latitude were made November 4, 5, 27, 28 ; telegraphic
signals for longitude were exchanged—

(1) with GREENWICH (through Alexandria and Porthcurno), November
14, 15,21, and 22;

(2) with Dr. AUWERS at LUXOR, December 1, 4, 10, and 15 ;

(3) with Mr. HUNTER at SUEZ, December 4, 5, 7, and 14.
The camp at Mokattam was struck December 25.

THE SITE ON THE MOKATTAM HILLS. (Plates VIII. and IX.)

The site selected, with the friendly assistance of WEYMAN DIXON, Esq., of
Cairo, who was intimately acquainted with the country, was on the western

L L 2

262 TRANSIT OF VENUS, 1874. EGYPT.

extremity of the ridge known as JEBEL JUISHI, which has the advantage of
being elevated about 600 feet above the plain of Cairo, and for this reason
was tolerably free from the mist that usually hung about the river and low
grounds. There was a road leading more than half-way up the hill to some
quarries, and a rough path the remainder of the way, over which country
carts could be taken with difficulty. Telegraphic communication with the
citadel was easily established with the assistance of Salamah Bey, Chief
Engineer of Egyptain Telegraph lines.

The northern meridian was clear to the horizon, and horizontal ground to
the eastward in the immediate vicinity of the station permitted the Model to
be placed where it could be conveniently observed with all the telescopes.

The general position of the station is shown in Plate VIII. ; the entire
encampment and relative positions of the instruments in Plate IX. The
exact position of the Transit instrument, with regard to prominent features of
the surrounding country, is fixed by the following bearings taken with the
Altazimuth, which was mounted for that purpose over the center of the Transit
Pier. The bearings are reckoned from North through East, South, and "West.
The North Meridian line fell upon parts of two Mosque-tombs in the same
field of view of the telescope as represented in Sketch N, Plate IX.

o /

North Meridan Marks (Sketch N, Plate IX.) o. o

Equatorial Drum of the Khedival Observatory (Sketch K) .. 10. i3

The Point marked in Sketch W 1 15. 44

The Point marked in Sketch M 106. 16

Summit of ruined Mosque near Fort Mokattam (Sketch P) . . 23i. 6

An angle of the Tower of Fort Mokattam (Sketch Q) 243. 5

Geometrical Summit of the GBEAT PYRAMID (Sketch R) . 248. 23|

Vane of Minaret of Mosque of Mohammed Ali in the Citadel

(Sketch S) 270. 5

The position of the center of the transit axis was permanently marked in
the following manner: — The stones being removed, a hole was bored in the
rock, a few inches deep, in which a small piece of iron was inserted and fixed
with Portland cement ; this was covered with layers of cement, sand, and soft
surface rock. Probably, by reference to the plan and bearings, no difficulty
would be experienced in recovering the spot. The transit piers were left
standing on the slab to the immediate South of their old position, but were
liable to be soon broken up and carried away.

C. ORDE BBOWNE.

PlaAe IX.

IT m

I

I

i

o

1 1

to S

»e

I I

MERIDIONAL OBSERVATIONS AT MOKATTAM. 263

The Transit instrument, with its fittings, mounting, and stone piers, and the
Transit Cloclc, with its solid tripod stand, were in every respect exactly similar
to the Honolulu instruments already described. The wooden observatory,
13 feet square, was also similar.

The great stone upon which stood the vertical piers was bedded in Port-
land cement laid on the surface of the solid rock. Observations for local
time were commenced October 24.

The stars observed for clock-error were taken generally from the list
employed at the Royal Observatory, Greenwich, the Right Ascensions being
brought up from the Greenwich Catalogue of 2760 Stars for the Epoch 1864.
For the determination of azimuth-error the stars a, 5, x Ursee Minoris, or
Cephei (Hev.) 51, were employed.

The valm of on,e revolution of the transit-micrometer-screw (which carried all
the wires of the reticule) was found by numerous observations of Polaris to
be 56"'43. The integer revolutions of the screw were numbered in the
observing-books so as to increase towards the screw-head ; the optic axis
coincided approximately with the center wire when the reading was 19r-7
(see Table XIV.). The position of the transit axis is always denoted by the
record of the micrometer-screw-head being on the East or West side of the
telescope.

The system of wires remained perfect during the observations, and the
equatorial intervals of the five vertical wires from the center wire were found
from the transits of 150 time-stars as follows : —

8

Wire I. (nearest to the screw-head) 28-610

» II 14-143

-. Ill o • ooo

» IV H'igfi

„ V. (farthest from the screw-head) . 28'58i

The imperfect transits are very few in number, and all the observations of
the polar stars were made at the center wire.

The mean of the five wires has been considered as sensibly coincident with
the center wire.

The Error of Level (Table XIII.) was found with the hanging spirit-level.
The value of the graduations engraved on the glass bubble was tested by the
makers before the Expedition left England, when it was found that
50 divisions were equivalent to one minute of arc, which value has been
always used.

264

TRANSIT OP VENDS, 1874. EGYPT.

The Pivot Correction was determined by repeated reversals of the instru-
ment as follows : —

1874, June 1 8, o'65i divisions

23, 'o38? „

24, -879
26, '990

29. '976 ,,

30, ' goo ,,
July i, -759 „

»

5)

A positive level-error was
greater with the Micro-
meter East than with the
Micrometer West.

The pivot correction applied to the level-error determined by spirit-level is
— 0"'94 Micrometer East and 4- 0"'94 Micrometer West.

The Zero of Gollimation has been obtained from observations of circumpolar
stars with reversed positions of the transit axis (Table XIV.).

The Error of Azimuth (Table XV.) has been found in the usual way, by
combining the observed transits of two stars, one of which was near the pole.

The transits of stars (Table XVI.) have been reduced as described in
Part I., page 15. The table contains only the transits observed in connection
with important operations, such as longitude signals and the actual transit of
Venus. When a transit was imperfect, or less than five bisections of a polar
star with the micrometer were obtained, the number of wires, or bisections,
observed is indicated by a numeral attached to the star's name thus : " e Eridani
(4)." For the polar stars the mean micrometer-reading corresponding to the
mean observed clock-time is also given with the star's name, and the micro-
meter-setting for Clock Stars is given at the foot of the page.

For the diurnal aberration a constant ( — 0"'27) has been embodied in the
correction for Gollimation ; the tabular Right Ascensions in Column 7 are
therefore not affected by it. "When a circumpolar star has been observed
with both positions of the instrument, each observation is separately reduced,
and the clock-slow for such observations is deduced, to exhibit the accuracy or
otherwise of the instrumental corrections.

The adopted error of the transit clock (Table XVII.) is the simple mean of all
the errors obtained on the day (omitting of course those obtained from polar
stars), and corresponds to the mean of the observed sidereal time in Column 3.
The adopted losing rate in Column G is the mean of the observed loss in the
24 hours preceding and following, and also corresponds to the mean of the
times. When the interval of time for which clock rate has to be allowed for any
species of observation exceeds six hours, the " loss in 24 hours " in Column 5

LATITUDE OF MOKATTAM. 265

has been used as the rate. Generally the interval is less than six hours, and
the " Adopted Rate " has been used.

ZENITH DISTANCES OBSERVED AT MOKATTAM, AND INFERRED CO-LATITUDE.

(Table XIX.)

The Vertical Circle, or Altazimuth, used at Mokattam was similar in every
respect to the Honolulu instrument. It was mounted on a pier of masonry
founded on the solid rock, and was protected by a wooden hut with a
revolving roof.

The mean corrections to the reading of the Vertical Circle for runs of the
four Micrometer screws for 100" were —

1874, November 4, +0-09
5, — 0-76

27, + o-o5

28, —0-17

The two levels parallel to the plane of the Vertical Circle were each
graduated with 30 divisions to one minute of arc. The Level Indication is
half the sum of the four readings. The Mercurial Barometer and the External
Thermometer, both by Messrs. Horne and Thornthwaite, were verified at
the Royal Observatory, Greenwich, and require no correction. The refractions
have been computed from the tables forming the Appendix to the Grecmuicli
Observations for 1853, and then reduced in the proportion of T0053 : 1.

The comparisons by which the error of the Altazimuth Clock was obtained
are given in Table XVIII. The error is required only for computing the
Reduction to tJie Meridian.

Co-latitude of Mokattam Station (Table XIX.)—

Mean of 6 Stars North of Zenith, 59. 58. 14-2 N.
6 „ South „ 59.58.13-1

Adopted Co-latitude of the Altazimuth Pier, 59°. 58'. 13"'6 N.

G. L. T.

266 TRANSIT OF VENUS, 1874. EGYPT.

LONGITUDE OF MOKATTAM STATION, BY WILLIAM ELLIS, ESQ.,
OF THE EOYAL OBSERVATORY, GREENWICH, AND CAPTAIN C.
ORDE BROWNE.

In introducing this section our first duty is to acknowledge the great
obligations of the Expedition to JOHN FENDER, Esq., M.P., Sir JAMES ANDERSON,
and the DIRECTORS of the EASTERN TELEGRAPH COMPANY, who gratuitously gave
the use of their submarine cables extending from Porthcurno in Cornwall to
Alexandria, for preliminary experiments, as well as for the final series of
signals, notwithstanding the serious interruption of the ordinary business
thereby entailed. The necessary " joining up " of the five separate cables, and
the transmission of time signals through such a length of wire that spealdng
was excessively inconvenient, was a very serious matter, but the operations
were entirely successful, owing chiefly to the personal superintendence and
forethought of Mr. EDWARD BULL, the Superintendent at Porthcurno.

Material aid was rendered by Mr. CROMWELL VARLEY, F.R.S., who kindly
lent his artificial cable, consisting of a large resisting coil and apparatus, by
which preliminary practice was obtained at Greenwich in- the special character
of signal required. Mr. Varley also suggested the system of signalling, dis-
tinguished hereafter as " Varley's method."

The first object of the preliminary experiments at Porthcurno was to
ascertain the possibility of obtaining a reliable signal through the great
length of cable between that place and Alexandria, which, it may be remarked,
is not only 638 knots longer than the Transatlantic cable used in the deter-
mination of the longitude of Washington, but has also a much smaller
section of copper.*

It was further necessary to decide on the arrangement of apparatus to be
employed, and to take steps to ensure that the same conditions should be ob-
served both at Porthcurno and Alexandria when the actual experiment should
take place. It was found that when Thomson's reflecting galvanometer was
employed in the usual way, the movement of the beam of light was feeble,
but that with an arrangement proposed by Mr. Bull an amply sufficient
length of travel was obtained. This arrangement consisted in the attach-

* The Porthcurno and Alexandria cable is 3,222 knots, and the French cable from Brest to
St. Pierre 2,584 knots, in length. The weights of copper wire and gutta-percha coating are respec-
tively 120 Ibs. and 175 Ibs. per knot for the English, and 400 Ibs. of copper and of gutta-percha
together for the French cable.

LONGITUDE OF MOKATTAM. 267

ment of the small mirror to the coil of a Thomson's syphon recorder, by which
its action was rendered much more sensitive than when used on the ordinary
galvanometer, by being brought into a strong magnetic field.*

Experiments were made with and without condensers. When no condenser
was used on the cable, the beam came to no fixed zero position, but was
subject to continual fluctuation. On the other hand, when a condenser
was employed at the sending end, the motion of the beam of light was
not sufficient to furnish a reliable signal.

The following was the arrangement finally adopted : — A condenser was
employed at the receiving end of the cable only — between the line and the
recording instrument. The mirror was used on the recorder in the manner
proposed by Mr. Bull, who also provided a similar instrument for use at
Alexandria in order to ensure the same conditions being observed at both
ends of the cable.

The same amount of line battery was used throughout both at Porthcurno
and at Alexandria, namely, 40 cells of Menotti or Daniell. Signals, how-
ever, were received at Porthcurno from Alexandria, to test the sensitiveness
of the instrument, with 12 Menotti cells, and messages were read from
Gibraltar with 3 Menotti cells. To keep up the magnetic field, 10 and 12
large batteries of the Daniell form were used, the size of the zinc plates being
about 1 foot square, and the resistance of the electro-magnet about 16 ohms.

The following are the particulars of the cables employed : —

Porthcurno to Vigo, 620 knots.
Vigo to Lisbon, 247 knots.
Lisbon to Gibraltar, 331 knots.
Gibraltar to Malta, 1,120 knots.
Malta to Alexandria, 904 knots.

The electrostatic capacity of the cable is 0'3645 microfarad per knot.
Specific inductive capacity of insulator, 0'0729 microfarad.

All possible assistance in Egypt was rendered by Mr. GIBBS, the Superin-
tendent; by Mr. STEVENSON, at Alexandria; and by Messrs. CROSS and EOGIERRI,
at Mokattam.

The Post Office Telegraph Department, represented by Mr. EATON, cordially

* In the Thomson recorder a coil of very fine wire is suspended vertically between the
extremities of a powerful electro-magnet depending on the action of a special batter}-. The coil is
brought into the actual line circuit ; hence a slight current through the line causes strong movement
of the coil.

M M

268 TRANSIT OF VENUS, 1874. EGYPT.

co-operated in completing the land line arrangements between Greenwich and
Porthcurno.

The longitudes of all the stations in Egypt at which observations of the
Transit of Venus were made in connexion with the British Expedition depend
fundamentally on that of Mokattam, the Mokattam Station being temporarily
connected with Alexandria by erecting a line from the citadel of Cairo to that
station. As it is unadvisable, with due regard to the safety of a submarine
cable, to attach thereto a land wire, it became necessary to divide the whole
line from Greenwich to Mokattam into sections, and make exchanges of
galvanic signals independently on each. The line naturally divided itself
into three sections : Greenwich — Porthcurno, Porthcurno — Alexandria, and
Alexandria — Mokattam. The days selected for exchanging signals were,
1874, November 14, 15, 21, and 22. On each of these days work was com-
menced by making exchanges of signals between Greenwich and Porthcurno,
and between Alexandria and Mokattam. These went on nearly simul-
taneously, and they were followed by exchanges between Porthcurno and
Alexandria, which occupied several hours. Finally, for security, a further
exchange was made between Alexandria and Mokattam, but that between
Greenwich and Porthcurno was not repeated. The exchange of November 14
combined with that of November 15, and the exchange of November 21
combined with that of November 22, gave, however, all requisite information
in regard to the rates of the chronometers used at Porthcurno.

The signals were given at all stations by means of an ordinary pair of
positive and negative keys. Those received on land lines were observed on
an ordinary upright galvanometer ; those received on the cable were observed
by use of a reflecting galvanometer, constructed, as before mentioned, by
fixing a light mirror to a Thomson's syphon recorder (the instrument
employed for the speaking work). The cable of the Eastern Telegraph
Company, as before mentioned, consists of sections as follows : — 1st, Porth-
curno to Vigo ; 2nd, Vigo to Lisbon ; 3rd, Lisbon to Gibraltar ; 4th, Gibraltar
to Malta ; and 5th, Malta to Alexandria. But, for the longitude work, the
whole of these were joined up into one continuous cable, without break or
instrument of any kind in circuit, and the signals were passed directly from
Porthcurno to Alexandria, or the reverse, through the whole length of cable.
The clock used at Greenwich for giving and receiving signals was the Sidereal
Standard (by which Greenwich time was determined). At Porthcurno a
mean solar chronometer (C. Frodsham 3205) was used for signalling with
Greenwich, and a sidereal chronometer (Reid and Sons 1207) for signalling
with Alexandria. At Alexandria a mean solar chronometer (Hewitt 890)
was alone used. At Mokattam the sidereal clock Dent 1914 was used

LONGITUDE OF MOKATTAM.

269

(by -which Mokattam time was determined). It will be thus seen that signals
given by a sidereal clock or chronometer would be observed by a solar
chronometer, and vice versa, so that (on account of the acceleration of sidereal
on solar time) the observer receiving signals would, in all cases, register every
variety of fraction of second. The observer at Porthcurno of course made
numerous comparisons of his two chronometers by the method of coincidence
of beats.

For further details concerning the methods of observation and reduction
employed the reader is referred to the notes and explanations attached, as
seemed desirable, to the various tables that follow.

TABLE I. — ERRORS and RATES of the SIDEREAL STANDARD CLOCK of the ROYAL

OBSERVATORY, GREENWICH.

Day,
Astro-
nomical,
1874.

Observer.

Name of Star.

Time by
Sidereal
Standard.

Sidereal
Standard
Clock Slow.

Sidereal
Standard
Clock Slow
reduced to
Standard
Observer
Criswick.

Mean
of
Times.

Mean
Clock Slow
reduced to
Standard
Observer
Criswick.

Daily
Losing
Rate.

Nov. 14

AD

a Andromedse

h in
O. I

•

+ 3 1"qO

s

+ 3rg3

h in

8

s

o. 6

+ 3i-g5

+ 3l'q8

e Andromedae

o.3i

+ 32-11

+ 32'I4

8 Piscium

O. 41

+ 3l-q6

+ 3l'QQ

o. 41

+ 3l'g5

20 Ceti

*;

o. 46

+3rqo

+3rq3

a Arietis

i . 5o

+3i'73

+ 3176

i5

c

<r Arietis

2. 4.4

+ 31-84

+ 31-84

— 0-07

t Arietis

2.5l

+ 3l'q4

+ 3l'Q4

a Ceti

2.55

+3r82

+ 3I-82

2.53

+ 3r87

8 Arietis

3. 3

+3r87

+ 3l-87

Nov. 19

c

Arcturus

H. 0

+ 3T26

+ 3I-26

20

e Andromedae

o. 3i

+3rig

+ 3rig

o Piscium

1.38

+ 3i'25

+ 3i-25

/3 Arietis

i. 47

+ 3ri7

+31-17

o. 24

+ 3T22

A1 Tauri

3.56

+ 3i'25

+3i"25

e Tauri

4. 2O

+3rig

+ 3l'IQ

22

C

a Andromedas

O. I

+ 3ri8

+3n8

+ O-QI

•y Pesrasi . .

o. 6

+ 3l'2Q

+3r2g

M

« Andromedse

o. 3 1

+ 3r3o

+ 3i'ig

jS Andromedae

I. 2

-f-3i'2g

+3i-i8

AT)

e Arietis

2.5l

+3r25

+ 3T28

a Ceti

2.55

+3i'23

+3i'26

2. 15

+ 31*24

o Tauri

3. 17

+3r22

+3r25

/Tauri

3. 23

+3i'25

+ 3i-28

e Eridani

3. 26

+3rio

+ 3l'22

S Eridani

3.36

+3ri2

+3i*i5

i; Tauri

3. 3g

4-3l'2O

+ 3r32

M M 2

270

TRANSIT OF VENUS, 1874. EGYPT.

The initials C, A D, and M are, respectively, those of Messrs. Criswick,
Downing, and Maunder, Assistants of the Royal Observatory. Mr. Criswick
is adopted as standard. The corrections applied to the " clock-slow " ob-
tained by Messrs. Downing and Maunder are respectively + O03 and
— Oil. These are the quantities determined from a discussion of the
whole of the observations taken by these observers during the year 1S74.
See Greenwich Observations for 1874, page lii.

The adopted values of the Royal Observatory Sidereal Standard Clock slow
are as follows : —

Approximate Greenwich

Sidereal Standard

Mean Solar Time of

Time by Sidereal

Clock Slow reduced

Exchange of Galvanic

Standard.

to Standard

Signals with Porthcurno.

Observer (C).

b

b m

8

1874, November 14, u

2. 40

-1- 3rq4

10, 7

22. OO

+ 3r88

21,11

3. 7

+ 3i-23

22, 7

23. 5

+ 31-24

These values are used (see Table II.) to infer the error of the chrono-
meter C. Frodsham 3205, at Porthcurno.

TABLE II. — DETERMINATION of the ERROR of the Mean Solar Chronometer
C. FRODSHAM 3205, at PORTHCURNO, on GREENWICH MEAN SOLAR TIME, by
exchange of GALVANIC SIGNALS between GREENWICH and PORTHCURNO.

•

a

AT GREENWICH.

AT PORTIICUKNO.

•
a

Whether

S>

T> 'li«n

Approximate
Greenwich
Mean Solar
Time.

ion giving Si

or
Negative
Signals
were
given.

d.

I

O

CM
O

a
S

02

•s

Means of the
Separate Groups
of Signals by
Sidereal Standard

Sidereal
Standard
Clock
Slow.

Means of the
Separate Groups
of Signals by
Chronometer
C. Frodsham 3205

Resulting Error
of C. Frodsham
3205, Slow on
Greenwich
Mean Solar

S

O

O

(Mean Solar).

Time.

(C

»

«

1874. h

h m s

s

h ni s

m s

Nov. 14, 1 1

G

Positive

I

53

2. I6.45-OO

+ 3i'94

10.40. O'22

+ i. 5 1 '02

P

Positive

2

5q

2.32. I7'34

+31-94

10. 55. 3o-oo

+ i . 5 1 • o3

G

Negative

3

49

2. 48. 30'OO

+3i-94

n. 11. 40-01

+ i. 5i -02

P

Negative

4

55

3. 3.37-58

+ 31-94

u. 26. 45-00

+ 1. 5i • 14

Nov. 1 5, 7

G

Positive

5

55

22. 25.45-00

+ 3i-88

6. 45. 40 ' g3

+ i.52-i8

P

Positive

6

5q

22.41.36-78

+ 3i-88

7. i.3o'oo

+ 1.52-28

G

Negative

7

49

22. 57.3O-OO

+ 3c88

7. 17. 20-65

+ I. 52'25

P

Negative

8

55

23. 14. 27-26

+ 3I-88

7. 34. i5-oo

+ i. 52'3g

LONGITUDE OF MOKATTAM.

271

Cu

00

3

AT GREENWICH.

AT PORTHCCUNO.

Whether

2

CB

Approximate
Greenwich
Mean Solar
Time.

CO

ho

•a
§
1

Positive
or

Negative
Signals
were
given.

G.

S

0

fo. of Signals in

Means of the
Separate Groups
of Signals by
Sidereal Standard
Clock.

Sidereal
Standard
Clock
Slow.

Means of the
Separate Groups
of Signals by
Chronometer
C. Frodsham 3205
(Mean Solar).

Resulting Error
of C. Frodsham
3205, Slow on
Greenwich
Mean Solar
Tim«.

co

i *

m

1874. h

h m s

a

h m s

m s

Nov. 21,11

G

Positive

9

53

2.43. o'oo

+ 3l'23

10.38. 22-53

+ 2. 7'32

P

Positive

10

55

2.58.55-24

+ 3i-23

10. 54. iS'oo

+ 2. 7-48

G

Negative

ii

5g

3. i5. 3o'oo

+ 3I-23

1 1. 10. 47- 14

+ 2. 7"3g

P

Negative

12

3. 3i. i5'62

+ 3i-23

1 1. 26. 3o-oo

+ 2. 7^7

Nov. 22, 7

G

Positive

i3

5i

22. 40. 3o'oo

+ 31-24

6. 32. 34-40

+ 2. 9-28

P

Positive

>4

61

22. 56. 28-42

+ 31-24

6. 48. 3o -oo

+ 2. 9'47

G

Negative

10

53

23. 12. 3O'OO

+ 31-24

7. 4. 29-08

+ 2. g-35

P

Negative

16

57

23. 28.33-75

+ 31-24

7. 20. 3o-oo

+ 2. 9'55

The observer at the sending station made contacts at intervals of 15 seconds ;
the times not fractional indicate means of times of contacts, a few in each
group being usually omitted to make the mean identical with the time of some
one particular contact.* The fractional times are the means of the observed
times of the corresponding signals at the receiving station, as noted on an
ordinary upright galvanometer. The signals were observed at Greenwich by
oye and ear in the same manner as at Porfchcurno, the sidereal chronometer
in the Computing Koom, sympathetic with the sidereal standard and chrono-
graph, being used.

TABLE III. — MEAN ERRORS on GREENWICH MEAN SOLAR TIME, and RATES of the
Mean Solar Chronometer C. FRODSHAM 3205, at PORTHCURNO, deduced
from the separate Determinations of the preceding Table.

Time by Chronometer
C. Frodsham 3205.

C. Frodsham 3205
Slow on
Greenwich Mean
Solar Time.

Daily Losing
Rate.

1874. h m
November 1 4, 1 1 . 4
1 5, 7. 10

m a

+ i.5i'o5

+ 1.52-28

8

+ i '47

November 21,11. 3

22, 6.57

+ 2. 7-44
+ 2. 9-41

+ 2-38

The errors of the chronometer C. Frodsham 3205 used in Table IV. depend
on the fundamental determinations of Table III.

* It would frequently happen that one or two signals in a group would be lost ; in such cases
one or two others would be omitted, as mentioned above, to make the group symmetrical, and so
lessen the labour of taking means.

272

TRANSIT OF VENUS, 1874. EGYPT.

TABLE IV. — COMPARISON at PORTHCURNO of the Chronometers C. FRODSHAM 3205
(Mean Solar) and REID AND SONS 1207 (Sidereal), by Coincidence of Beats,
for Determination of the ERROR of REID AND SONS 1207 on G-REENWICH
SIDEREAL TIME.

Approximate
Greenwich Mean
Solar Time.

Time by
C. Frodsham 3205
(Mean Solar).

C. Frodsham 3205
Slow on Greenwich
Mean Solar Time.

Time by
Reid and Sons 1207
(Sidereal).

Resulting Error of
Reid and Sons 1207,
Slow on Greenwich
Sidereal Time.

1874. h

h m 8

m s

h m 9

m s

November 14, 9

g. 2.27-0

+ i.5o-g3

o. 41. 45-0

- 2. I7'3g

9

9. 5.27'0

+ I. 5o'g3

0.44.45-5

- 2. 17-40

10

9. 38. 21-0

4- i.5o-g6

I. 17.45-0

— 2. '7'47

12

11.41. 5'5

+ i.Si'og

3. 20. 5o*o

- 2.17-67

12

11.44. 5'o

-f i.Si'og

3. 23. 5o-o

- 2. I7'6g

12

11.47. 4'5

+ i.Si'og

3. 26.5o-o

- 2. I7'6g

12

12. 16. 49*5

+ I. 5l ' 12

3. 56. 40-0

- 2. 17-77

13

12.37. 46'o

+ i.5i -i5

4. 17. 40-0

— 2. 17-80

November 14, 1 6

16. 24. 25 -o

+ i.5i-38

8. 4.57-0

- 2. 18-35

16

16. 27. 20-0

+ i.5i-38

8. 7-52-5

— 2. I8-37

«7

16.45. 17-0

+ i.5i'4o

8. 25.52-5

— 2. 18-40

i7

17. o. i5'o

+ i.5i'4i

8.40.53-0

— 2. 18-42

i7

17. 3. 18-0

+ 1.51-42

8. 43. 56-5

— 2. 18-42

19

18. 44. i8'o

+ i.5i'52

10. 25. i3'5

— 2. 18-71

19

18. 47. zo'o

+ i.5i'52

10. 28. 16-0

— 2. 18-72

November i5, 5

5. 7.45-0

+ i.52'i6

20. 5o. 23'5

— 2.18-66

5

5. 10. 5i -o

+ i.52'i6

20. 53. 3o-o

— 2. 18-65

5

5. i3. 45-0

+ i.52-i6

20. 56. 24-5

— 2. 18-68

8

8. 22. 5g-o

+ 1.52-36

o. 6. 10-0

— 2. 18-89

9

8.37. 53-o

+ i.52'37

0.21. 6-5

— 2. l8-g3

9

8.55.55-0

+ i.52'3g

o. 3g. ii -5

— 2. i8-g5

November i5, 10

9.34.40-0

+ 1.52-43

i. 18. 3-o

— 2. 19-04

ii

10. 3l. 22"O

+ 1.52-49

2. 14. 54-5

- 2. 19-17

12

12. 9. 55 'o

+ i.52-5g

3. 53.44-0

- 2.I9-37

12

12. 1 3. O'O

+ i.52-5g

3. 56. 49-0

— 2. ig-36

November 21,12

n. 5o. 25'o

+ 2. 7'52

3.58. g-5

- 2.23-77

12

ii. 56. 25 -o

+ 2. 7'52

4. 4. io'5

— 2. 23-78

12

12. 2.3o'0

+ 2. 7-54

4. 10. i6-5

— 2.23-76

12

12. 8.37-0

+ 2. 7-55

4. 16. 24-5

— 2. 23-75

November 21, 17

17. 5. 6-0

+ 2. 8-04

g. 1 3. 43 • o

— 2. 24'o5

'7

17. 8. o-o

+ 2. 8-04

g. 16.37-5

— 2. 24-08

'7

17. n. 6-0

+ 2. 8-o5

g. ig. 44-0

— 2. 24fo5

November 22, 6

5. 3i. 45-0

+ 2. 9-27

21.42. 26-0

— 2. 24- l6

6

5.34.43-0

+ 2. 9-27

21. 45. 24 '5

— 2. 24-18

6

5.37.44-0

+ 2. 9-27

21. 48. 26-0

- 2.24-17

8

7.39.45-0

+ 2. 9-48

23. 5o. 47-5

- 2.24-41

8

7. 42. 46*0

+ 2. 9 '49

23. 53. 4g"o

- 2.24-41

8

7.45.42-0

+ 2. 9'49

23.56.45-5

— 2. 24-43

LONGITUDE OF MOKATTAM.

273

Approximate
Greenwich Mean
Solar Time.

Time by
C. Frodsham 3205
(Mean Solar).

C. Frodsham 3205
Slow on Greenwich
Mean Solar Time.

Time by
Reid and Sons 1207
(Sidereal).

Resulting Error of
Reid and Sons 1207,
Slow on Greenwich
Sidereal Time.

1874. »
November 22, 12

12
12

h m 9
12. 6. 48-0
12. 9.42*0
12. 1 5. 45-O

m s

+ 2. 9'92
+ 2. 9-92

+ 2- 9'94

h m s
4. 18.32-0

4. 21. 29 '5
4. 27. 33 '5

m s
— 2. 24-62
— 2. 24'63
— 2.24-62

The lines in the preceding table show the division into the groups from
which the following mean errors of Reid and Sons 1207 are obtained.

TABLE V. — MEAN ERRORS and RATES of the Chronometer REID AND SONS 1207
(Sidereal) deduced from the Comparisons (at PORTHCUKNO) with the
Chronometer C. FRODSHAM 3205 (Mean Solar).

Approximate
Greenwich
Mean Solar Time.

Time by
Reid and
Sons 1207.

Held and Sons 1207 Slow on Greenwich Sidereal Time

Hourly
Losing
Rate.

By Comparison with
C. Frodsham 3205.

As inferred from
the Direct
Determinations of its
own Error.

Adopted
Chronometer
Slow.

I874. h

Nov. 1 4, 1 1
i?

io, 7
1 1

h m

2.3g
9. o

22.38
2. 5l

m s
— 2. 17-61 (a)
— 2. 18-48 (l>)

~ 2. 18-79 (c)

- 2. 19-24 (d)

m s
- 2. 17-98 (i)

- 2. 19-04 (k)

m s
— 2. 17-61
— 2. 18-23

s
— 0-098

— 2. 18-79
- 2. 19-14

— o-o83

NOV. 21,12

«7

22, 7
12

4- 7
9-'7

22. 5o

4.23

- 2.23-77 (e)
— 2.24-06 (/)

- 2.24-29 (g)
— 2. 24-62 (h)

— 2. 23'gi (I)

— 2.24-44 (m)

- 2.23-77
- 2.23-99

—0-043

— 2. 24^29
— 2.24-53

—0-043

The results (a), (c), (e), and (g) are obtained from comparisons with the
chronometer C. Frodsham 3205 made near to times of determination of
the error of the latter by the exchange of galvanic signals with Greenwich ;
they may, therefore, be adopted as fundamental determinations of the error
of Reid and Sons 1207.

The results (b), (d), (/), and (h) depend upon a " chronometer slow " of
C. Frodsham 3205, inferred from the fundamental errors of that chronometer
given in Table III. ; they are, therefore, affected with any possible irregularity
of rate of that chronometer. The results (i) and (k) are inferred from those

274

TRANSIT OF VENUS, 1874. EGYPT.

of (a) and (c), and the results (?) and (m) from those of (e) and (g) ; these are
similarly affected with any irregularity of rate of the chronometer Reid and
Sons 1207 itself. That is to say, the results (b) and (i) depend, the former
on the steadiness of rate of C. Frodsham 3205, the latter on the steadiness of
rate of Reid and Sons 1207, and the mean of the two values may be adopted
for the error of Reid and Sons 1207 at this epoch. Similarly for (d) and (&),
for (/) and (I), and for (h) and (m).

The errors of the chronometer Reid and Sons 1207 used in Table VI.
depend on the numbers contained in the fifth and sixth columns of the pre-
ceding table.

TABLE VI. — DETERMINATION of the ERRORS of the MEAN SOLAR CHRONOMETER
HEWITT 890, at ALEXANDRIA, on GREENWICH MEAN SOLAR TIME, by ex-
change of GALVANIC SIGNALS between PORTHOURNO and ALEXANDRIA, through
the SUBMARINE CABLE of the EASTERN TELEGRAPH COMPANY.

Whether

S1

AT PORTHCCKNO.

AT ALEXANDRIA.

Make or

8

r*,

Approximate
Greenwich
Mean Solar
Time.

_

'So

a
.0

3

CO

Signals
were given
or whether
Varley's
Method
was em-
ployed.

i
o
O

•s

1

No. of Signals in <

Means of the
separate Groups
of Signals by
Chronometer
Reid and Sons
1107 (Sidereal).

Reid and Sons
1207 Slow of
Greenwich
Sidereal Time.

Means of the
separate Groups
of Signals by
Chronometer
Hewitt 890
(Mean Solar).

Resulting Error
of Hewitt 890
Slow on Green-
wich Mean
Solar Time.

1874. h

h m s

m s

h m s

h m s

Nov. 14, 14

p

Make

'7

10

5. 8. 1 8-00

— 2. I7'85

i5. 27. 58-5i

— . 57. 5 1 "69

„

p

Break

18

10

5. 7. 48-00

— 2. 17-80

i5. 27. 28-53

— .57.51-64

„

A

Make

19

18

5.22. 9-77

— 2. 17-88

1 5. 41. 45-00

— .57.48-72

„

A

Break

20

i5

5.22. 9-78

— 2. 17-88

1 5. 41. 46-00

- .57.4871

n

P

Make

21

i5

5. 37. o-oo

- 2. 17-90

1 5. 56. 35-45

n

P

Break

22

>4

5. 36. 3o-oo

— 2. 17-90

i5.56. 5-56

— .57.5I-42

„

A

Make

23

17

5. 52. 29-96

— 2. I7-93

1 6. 12. o-oo

— 5? 4.8*55

»

A

Break

24

H

5. 52. 44-96

- 2. 17^3

16. 12. 10-00

— .57.48-59

Nov. 14, 1 5

P

fVarley'sl

25

'4

6. 21. 3o-oo

- 2. 17-97

16.40. 59-28

— . 57. 5z-58

,,

A

t Method J

26

>4

6.55. 11-21

— 2. i8-o3

17. 14.30-00

— . 57. 47-67

16

P

27

20

7. 22. 3O'OO

— 2. 18-07

17.41.49-01

— .57.52-41

„

A

28

'9

7. 52. 50-87

— 2. 18-12

1 8. 12. O'OO

- .57.47-54

<7

P

29

12

8. 17. 3o'oo

— 2. 18-16

18.36.3978

— .57.52-28

A

3o

10

8. 32. 27-51

- 2.18-19

18. 5i. 3o'oo

- -57.47-46

Nov. 1 5, 8

P

Make

3i

18

23. 58. 45-00

— 2. 18-90

10. i5. 18-43

— .57.00-87

„

P

Break

32

12

23. 5g. o'oo

— 2. 18-90

10. 1 5. 33-33

— .57.50-81

9

A

Make

33

"7

o. 14. i -86

— 2. 18-92

10. 3o. 3o-oo

— .57.48-11

,»

A

Break

34

18

o. 14.31-78

— 2. 18-92

10. 3i. o-oo

— .57.48-27

j,

P

Make

35

12

o. 29. 45-00

— 2. i8-94

10. 46. 1 3-33

— . 57.50-89

„

P

Break

36

20

o. 3o. o-oo

— 2. 18-94

10. 46. 28-08

- .57.50-68

„

A

Make

37

i5

o. 45. 6-97

— 2. 18-96

ii. i . 3o-oo

— .57.48-13

»

A

Break

38

12

o. 45. 21-90

— 2. 18-96

11. 1.45.00

— .57.48-24

LONGITUDE OF MOKATTAM.

275

00

Whether

£-
a

AT PORTHCURNO.

AT ALEXANDRIA.'

1

Make or

S:

a

T? T

rl

Approximate
Greenwich
Mean Solar
Time.

Station giving Sig

j>reaK
Signals
were given
or whether
Varley
Method
was em-
ployed.

=-.

2

O

•8

6
ft

No. of Signals in (

Means of the
separate Groups
of Signals by
Chronometer
Keid and Sons
1207 (Sidereal).

Reid and Sons
1207 Slow of
Greenwich
Sidereal Time.

Means of the
separate Groups
of Signals by
Chronometer
Hewitt 890
(Mean Solar).

Resulting Error
of Hewitt 890
Slow on Green-
wich Mean
Solar Time.

.874- "

h in s

m s

h m s

h m s

Nov. 1 5, 9

P

fVarley'sl

39

12

1 . 7. 3o-oo

— 2. ig'oo

11.23. 53-35

— .57.52-I5

10

A

[Method j

40

'4

i. 37. 16-49

— 2. 19^04

1 1 . 53. 3o-oo

— .57.47-24

j>

P

4«

16

2. 3. 3o-oo

— 2. 19-08

12. 19.43-95

— .07.52-01

11

A

42

'9

2. 33. 56-07

— 2. ig-12

12.50. O'OO

— .57.47-02

V

P

43

20

3. 2.3o-oo

— 2. ig-l6

1 3. 18. 34-07

— . 57.51-87

12

A

44

12

3.3i.35-63

— 2. 19-20

1 3. 47. 3o-oo

- -57.46^9

Nov. 21, i3

P

Make

45

i3

5. 34. o-oo

— 2. 20-83

i5. 25. 54-18

— .57.46-91

!5

P

Break

46

i3

5. 34. 1 5-oo

— 2. 23-83

i5. 26. 9-09

— .57.46-87

H

A

Make

47

23

5. 49. 41-00

— 2. 23-84

1 5. 41. 3o-oo

— . 57. 44 '32

»

A

Break

48

24

5. 49. 40-93

— 2. 23-84

1 5. 41. 3o~oo

— .07.44-39

»

P

Make

49

21

6. 7. o'oo

- 2.23-86

15.58.48-81

— . 57. 46-98

»

P

Break

5o

•7

6. 7. iS'oo

— 2. 23-86

i5. 5g. 3*55

— .57.46-77

»

A

Make

5 1

22

6. 24. 46-77

— 2.23-87

1 6. 16. 3o'oo

— . 57. 44-33

»

A

Break

52

21

6.25. 1-74

— 2. 23-87

1 6. 16. 45*00

- .57.44-40

Nov. 21, 1 5

P

[Varley's]

53

17

6. 47. o'oo

— 2.23-88

16. 38. 43-61

— . 07. 48-35

)>

A

[Method J

54

'9

7. 18. 26-74

— 2. 23-gi

17. 10. o-oo

— . 57. 43-19

16

P

55

H

7. 42. 3o-oo

— 2. 23-92

17.34. 4-35

— .07.48-24

»

A

56

>7

8. 7.34-86

— 2. 23'94

17. 5g. o-oo

- .57.43-i5

5)

P

57

25

8.32. o-oo

— 2. 23-96

18. 23. 20-98

— .57.48-01

17

A

58

17

8. 58. 43-38

— 2. 23-98

18. 5o. o-oo

— . 57. 43-05

Nov. 22, 8

P

Make

59

18

o. 29. 45-00

— 2. 24-36

10. 18. 31-49

— .57.45-83

)»

P

Break

60

22

o. 3o. o-oo

— 2. 24-36

10. 18. 46-52

— . 57. 45-90

9

A

Make

61

23

o. 49. iq-o5

- 2.24-37

10. 38. o-oo

— .57.43-51

?»

A

Break

62

18

o. 48.48-98

— 2.24-37

10. 37.30-00

— . 57. 43-00

»

P

Make

63

24

i. 5.45-00

— 2. 24-39

10. 64. 25-6g

— . 57. 45-96

>j

P

Break

64

'9

i. 5. 45-00

— 2. 24-39

10. 54. 20-60

- .57.45-87

»

A

Make

65

29

I. 22. 54-84

- 2.24-40

11. u. 3o-oo

— . 57. 43-26

»>

A

Break

66

25

1.23. 9-88

— 2. 24-40

11. 11. 45-00

— .57.43-26

Nov. 22, i o

P

fVarley'sl

67

'7

1.45. o'oo

— 2.24-42

u.33.35'44

- .57.47-17

»

A

[Method J

68

12

2. 21. 5'2I

— 2. 24-44

i 2. g. 3o-oo

— . 57. 42-46

1 1

P

69

'9

2. 45. O'OO

— 2. 24-46

12. 33. 25'47

- -57-47'°7

)>

A

7°

17

3. 10.43-56

— 2. 24-48

I2.5g. o-oo

— . 07. 42-28

»

P

7'

18

3. 35. 3o-oo

— 2. 24-49

1 3. 23. 47-00

— . 57. 46-90

12

A

72

i3

4. 3. 52-40

— 2. 24-5l

1 3. 52. o-oo

- .57.42-17

In the make and break method the circuit was completed and broken at
the sending station at intervals of 15 seconds, the operator using alternately
the positive and negative key. At the receiving station the first start of the
beam of light was the phase of signal observed. The signals referring to
completion of the circuit are collected into one group, without distinction of
quality, positive or negative ; and those referring to break of the circuit into

N N

276

TRANSIT OF VENUS, 1874. EGYPT.

another group ; these groups are indicated in the table above by the words
" make " and " break " respectively.

In what is called Varley's method the circuit was completed at the
sending station for 50 seconds, and broken for 10 seconds, using alternately
the positive and negative key. The signals corresponding to break of circuit
only were made use of. At the receiving station* the extent of motion of
the beam of light, from zero on the scale, having been first noted, a mark
was made at the middle point of its excursion. Just before the expected
break, the circuit at the sending station will have been closed for nearly
50 seconds, and the beam of light at the receiving station will have come to
rest. At this moment the observer shifts the position of the scale so as to
bring the beam to the zero point, and, on break of the circuit, notes the time
at which the beam transits the provisional mark, which is the phase of signal
observed. The groups are formed without any distinction as to quality of
current, positive or negative.

The times not fractional indicate means of times of contacts at the sending
station, one or two times being occasionally omitted to make the mean
identical with the time of some one particular contact, or with a time half
way between those of two successive contacts. The fractional times are the
means of the observed times of the corresponding signals at the receiving
station, noted as described above. Two times are by chance not fractional,
4P'00 in Group 47, and 47S-00 in Group 71 ; they however indicate, as a
little consideration would show, means of times of signals received.

We have, in the preceding table, the error of Hewitt 890 (at Alexandria)
on Greenwich Mean Solar Time ; it is now necessary to find the error of the
same chronometer on Mokattam Mean Solar Time.

From the numbers given in Table XVII. (page 314), Errors and Rates of
the Mokattam Sidereal Clock, Dent 1914, were adopted as follows : —

Dent 1914 Slow oil

Approximate Mokattam

Mokattam Sidereal

Adopted Daily

Mean Solar Time.

Time (at oh. Sid.

Losing Eate.

Time).

1874. "

s

s

November 14, 8

+ 1 4'oo

+ 0-29

i5, 8

+ 14-28

+ 0-29

21, 8

+ 17*04

+ 0-62

22, 8

+ 17*78

+ 078

These errors and rates are determined entirely from the observations of

* As before mentioned a condenser was placed in the circuit, between the line and the recording
instrument, to improve the character of the signal.

LONGITUDE OF MOKATTAM.

277

Captain Browne, and are employed to infer the errors of Dent 1914, contained
in the next table.

TABLE VII. — DETERMINATION of the ERROR of the MEAN SOLAR CHRONOMETER
HEWITT 890, at ALEXANDRIA, on MOKATTAM MEAN SOLAR TIME, by exchange
of G-ALVANIC SIGNALS between MOKATTAM and ALEXANDRIA.

2

AT MOKATTAM.

AT ALEXANDEIA.

•
d

Whether

8

O

Approximate
Mokattam
Mean Solar
Time.

Station giving Sig

Positive

or
Negative
Signals
were
given.

No. of Group.

_a
•

•a

a
bD

cc
'o
6
fc

Means of the
separate Groups
of Signals by
Mokattam
Sidereal Clock
Dent 1914.

Mokattam
Sidereal Clock
Slow on
Mokattam
Sidereal Time.

Means of the
separate Groups
of Signals by
Chronometer
Hewitt 890
(Mean Solar).

Resulting Error
of Hewitt 890
Slow on
Mokattam
Mean Solar
Time.

1874. "

h m s

a

h m s

m s

Nov. 14, 14

M

Positive

73

83

5.21. O-OO

+ 14-06

i3.38. 22-29

+ 7. 16-43

91

A

Positive

74

77

5. 38. 20-46

+ H"°7

i3. 55.40*00

+ 7- i6-35

99

M

Negative

75

81

5. 09. 40-00

+ i4-°7

14. 16. 55-98

+ 7. 16-42

99

A

Negative

76

79

6. 16. 41-72

+ 14-08

14. 33. So'oo

+ 7. 16-34

Nov. 14, 20

M

Positive

77

79

u. i3. 3o-oo

+ 14-14

19. 29. 54-42

+ 7. i6-63

99

A

Positive

78

73

H.33. 1870

+ i4'«4

19. 49.40-00

4- 7. i6-5o

99

M

Negative

79

81

1 1. 5o. 5o-oo

+ H'H

20. 7. 8-28

+ 7. 16-66

99

A

Negative

80

7i

12. 7. 24-31

+ H'lS

20. 23. 40-00

+ 7- l6"54

Nov. 1 5, 10

M

Positive

81

85

o. 58. 3o'oo

+ i4'29

9. 12. 38-97

+ 7. 17-06

»

A

Positive

82

77

i. i5. 48-80

+ 14-30

9. 29. 55-Qo

4- 7. 17-00

99

M

Negative

83

1 1

I. 26. lO'OO

+ i4'3o

9. 40. 14-31

+ 7.17-20

99

A

Negative

84

46

i. 35. 56-g3

4- 14-30

9. 5o. o-oo

+ 7. 16-84

Nov. 1 5, 16

M

Positive

85

83

7. 24. 40-00

+ '4-37

15.37. 45-52

+ 7- 17-34

99

A

Positive

86

69

7.42. i7-3g

+ I4-37

i5. 55. 2o'oo

+ 7. 17-36

n

M

Negative

87

53

7. 55. 20-co

4- 14-38

1 6. 8.20-55

+ 7- 17-29

99

A

Negative

88

7i

8. 9. 5i-88

+ 14-38

16. 22. 5o-oo

+ 7- I7-34

Nov. 21, 14

M

Positive

8q

63

6. o. 20-00

+ 17-20

1 3. 5o. 3- 1 9

+ 7. 20-84

n

A

Positive

qo

40

6. 17. ig-65

+ 17-20

14. 7. o-oo

4- 7. 20-90

99

M

Negative

91

85

6. 32. 3o-oo

+ 17-21

14.22. 7-89

+ 7. 20-88

99

A

Negative

92

4'

6. 48. 24-74

+ 17-22

14.38. o-oo

+ 7-20"9'

Nov. 21, 20

M

Positive

93

83

1 1.33. 40-00

+ I7-34

ig. 22. 28-40

+ 7. 2i-i5

»

A

Positive

94

73

1 1.49. 34-03

+ I7-35

iq. 38. 2O'oo

+ 7. 2 I -00

99

M

Negative

q5

73

12. 7. o-oo

+ I7-35

19. 55. 42-99

-f 7. 21-12

9>

A

Negative

96

70

12. 22. 39-46

+ i7-36

20. II. 2O-00

+ 7- 21'02

Nov. 22, 9

M

Positive

97

79

o. 5i. 5o-oo

+ 17-81

8.38.27-47

+ 7.2179

»

A

Positive

98

73

I. 7.34-99

+ 17-82

8. 54. lo'oo

+ 7. 21-68

99

M

Negative

99

79

i. 23. 3o-oo

+ I7'83

9. 10. 2'3i

+ 7-21-78

99

A

Negative

IOO

77

1.40. 0-34

+ I7'83

9. 26. 3o-oo

+ 7.21-73

Nov. 22, i5

M

Positive

1OI

75

6. 3o. o-oo

+ 17-99

14. i5. 41*93

4- 7- 22-11

99

A

Positive

102

61

6. 45. 2o-5o

4- 18-00

14.31. o-oo

+ 7. 22-04

»

M

Negative

io3

83

7. o. 5o-oo

+ 18-01

14. 46. 26-86

4- 7.22-16

99

A

Negative

104

67

7. 1 5. 55-49

+ 18-02

1 5. i.3o-oo

4- 7. 22-04

NN 2

278

TRANSIT OF VENUS, 1874. EGYPT.

The observer at the sending station made contacts every 10 seconds ; the
times not fractional indicate means of times of contacts, a few in each group
being usually omitted to make the mean identical with the time of some one
particular contact. The fractional times are the means of the observed
times of the corresponding signals at the receiving station, as noted on an
ordinary upright galvanometer.

TABLE VIII. — MEAN ERRORS on MOKATTAM MEAN SOLAR TIME and KATES of the
MEAN SOLAR CHRONOMETER HEWITT 890, at ALEXANDRIA, deduced from the
separate determinations of the preceding table.

Time by Chronometer
Hewitt 890.

Hewitt 890 Slow
on Mokattam
Mean Solar Time.

Hourly Losing
Kate.

1874. h m
November 14, 14. 6
19. 58

m s
+ 7. l6-3g

+ 7. 1 6-58

s

+ o-o32

November 1 5, 9. 33
16. i

+ 7- I?'02

+ 7. 17-33

+ 0-048

November 21, 14. 14
19.47

-t- 7. 20-88
+ 7. 21-07

+ 0-064

November 22, 9. 2
14.39

+ 7.21-74
+ 7.22-09

+ 0-062

TABLE IX. — DEDUCED LONGITUDE of MOKATTAM, EAST of GREENWICH, for each
separate group of cable signals, found by combining the DETERMINED
ERRORS of the MEAN SOLAR CHRONOMETER HEWITT 890 (at ALEXANDRIA) on
GREENWICH and MOKATTAM MEAN SOLAR TIMES.

By Exchange

By Exchange of Galvanic Signals between
Porthcurno and Alexandria.

of Galvanic
Signals between
Mokattam and

Approximate
Greenwich
Mean Solar

Alexandria.

Resulting
Longitude of
Mokattam

Time.

Station

Make or
Break

Hewitt 890
Slow of

Hewitt 890
Slow of

East of
Greenwich.

No. of
Group.

giving
Signals.

Signals, or
Varley's

Greenwich
Mean Solar

Mokattam
Mean Solar

Method.

Time.

Time.

1874. "

h m s

m s

h m s

November 14, 14

17

P

Make

— i. 67. 5r6q

+ 7- 16-43

2. 5. 8-12

»

18

P

Break

61-64

16-43

8-07

'9

A

Make

48-72

16-44

5-i6

j?

20

A

Break

48-71

16-44

5-i5

LONGITUDE OP MOKATTAM.

279

By Exchange

By Exchange of Galvanic Signals between
Porthcurno and Alexandria.

of Galvanic
Signals between
Mokattam and

Approximate
Greenwich

Alexandria.

Resulting
Longitude of

Mean Solar

Mokattam

Time.

Nn nf

Station

Make or
Break

Hewitt 890
Slow of

Hewitt 890
Slow of

East of
Greenwich.

.>!'. (11

Group.

giving
Signals.

Signals, or
Varley's

Greenwich
Mean Solar

Mokattam
Mean Solar

Method.

Time.

Time.

I874. »•

b m s

m s

b m s

November 14, 14

21

P

Make

— i. 07. 5i'3g

+ 7. 16-45

2. 5. 7-84

)>

22

P

Break

5 1 -42

16-45

7-87

»

23

A

Make

48'55

16-46

5-01

»

24

A

Break

48-5g

16-46

5-o5

November 14, i5

25

P

fVarley'sl

— i. 67. 52'58

+ 7- 16-47

2 . 5. g-o5

?»

26

A

[Method J

47-67

16-49

4-16

16

27

P

52-41

1 6-5 1

8-92

)»

28

A

47-54

i6-52

4-06

'7

29

P

52-28

16-54

8-82

»

3o

A

47-46

16-04

4-00

November i5, 8

3i

P

Make

— i. 57. 50-87

+ 7- >7'°5

2. 5. 7-92

?>

32

P

Break

5o-8i

17-05

7-86

9

33

A

Make

48-11

17-07

5-i8

34

A

Break

48-27

17-07

5-34

35

P

Make

5o-8g

17-08

7'97

36

P

Break

5o-68

17-08

776

37

A

Make

48-13

17-09

5'22

38

A

Break

48-24

17-09

5-33

November i5, 9

39

P

fVarley'sl

— i. 57. 52-i5

+ 7- 17'n

2. 5. 9-26

10

40

A

[Method J

47-24

!7'i3

4-37

»>

4'

P

52-oi

17-15

9-16

1 1

42

A

47-02

17-18

4-20

»

43

P

5i-87

17-20

9-07

12

44

A

46-99

17-22

4-21

November 21, 1 3

45

P

Make

— i. 57. 46-91

4- 7. 20-92

2. 5. 7-83

j)

46

P

Break

46-87

20-92

779

'4

47

A

Make

44-32

20-g3

5-25

)>

48

A

Break

44-39

2O-g3

5-32

)»

49

P

Make

46-98

20-94

7'92

»>

5o

P

Break

46-77

20-94

7-71

»

5i

A

Make

44-33

zc-gS

5-28

5»

52

A

Break

44-40

2o-g5

5-35

November 21, i5

53

P

fVar ley's]

— i. 57. 48-35

+ 7. 20-96

2. 5. g-3i

jj

54

A

[Method J

43-19

20-98

4'«7

16

55

P

48-24

20-gg

g-23

»)

56

A

43-i5

2T01

4-16

»

57

P

48-01

21-02

g-o3

17

58

A

43'o5

21-04

4-09

280

TRANSIT OF VENUS, 1874. EGYPT.

By Exchange

By Exchange of Galvanic Signals between
Porthcurno and Alexandria.

of Galvanic

Signals between
Mokattam and

Approximate
Greenwich
Mean Solar

Alexandria.

Resulting
Longitude of
Mokattam

Time.

Station

Make or
Break

Hewitt 890
Slow of

Hewitt 890
Slow of

East of
Greenwich.

No. of
Group.

giving
Signals.

Signals, 01
Varley's

Greenwich
.Moan Solar

Mokattam
Mean Solar

Method.

Time.

Time.

1874. *

h 111 3

m s

h m s

November 22, 8

59

P

Make

- I.57.45'83

+ 7.21-82

2. 5. 7-65

»

60

P

Break

45'go

21-82

772

9

61

A

Make

43-5l

21-84

5-35

>j

62

A

Break

43'5o

21-84

5-34

»

63

P

Make

45-96

21-86

7-82

»

64

P

Break

45-87

21-86

7-73

»

65

A

Make

43-26

21-87

5-i3

»>

66

A

Break

43-26

21-87

5-i3

November 22, 10
j»

67
68

P

A

,rVarley's")
[Method /

- 1.57.47-17
42-46

+ 7-2I'9°
21-94

2. 5. 9-07
4-40

ii

69

P

47-07

21-96

g-o3

»

70

A

42-28

zi'99

4-27

»

7'

P

46-90

22-01

8-9 1

12

72

A

42-17

22-04

4-21

I

2

3

4

5

6

7

The numbers in column 5 are those found in Table VI., and the numbers in column 6 are
inferred from those in Table VIII.

LONGITUDE OF MOKATTAM.

281

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282

TRANSIT OF VENUS, 1874. EGYPT.

° 3 -i

£ A §>
» ° X

u^

r^

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ON
00

ro
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ON
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bn (D C •

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November 21

November 22

November 14

November i5

November 21

November 22

LONGITUDE OF MOKATTAM.

283

v. .3

c

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m

p

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284

TEANSIT OF VENUS, 1874. EGYPT.

TABLE XII. — COLLECTION of RESULTS for RETARDATION of the G-ALVANIC CURRENT

in the SUBMARINE CABLE.

Day 1874.

Cable Retardation given by the

Make
of Circuit.

No. of
Cable
Signals.

Break
of Circuit.

No. of
Cable
Signals.

Varley
Method.

No. of
Cable
Signals.

I

8

3

November 1 4
i5

21
22

2'8c)
2-75

2'6l

2'5o

60
62
79
94

2-87
2'47
2^2
2^8

53
62
75
84

4-86

4'9°
5-o5

471

89
93
109

96

Means

2 '69

2g5

2-56

274

4-88

387

These values apply to the retardation in the cable portion of the line only ;
the land retardation and the effect of personal equation in the land signalling,
both in England and Egypt, being eliminated by the method of reduction
employed. But they are affected by Mr. Ellis's manner of giving and
receiving cable signals at Porthcurno, and by Mr. Hunter's manner of giving
and receiving cable signals at Alexandria ; and these influences cannot be
separated. The error thereby introduced into the retardation (judging by
the numbers given on pages 285 and 286) is presumably small.

The mean of the results from the " make " and " break " methods gives
2S<62 for the sum of the cable retardations in both directions, or ls<31 for the
retardation between Porthcurno and Alexandria, or between Alexandria and
Porthcurno.*

The value 4S<88 includes the sum of the cable retardations in both direc-
tions + the time occupied by the beam at both stations (Porthcurno and
Alexandria) in reaching the middle point of its excursion.

CORRECTION of the GREENWICH-MOKATTAM LONGITUDE for the effects

of PERSONAL EQUATION.

The Greenwich-Mokattarn longitude requires correction for the personal
equations between the observers who gave and received signals, and for the
difference of the manner in which the observers at Greenwich and Mokattam

Mr. Varley had estimated the retardation each way at

LONGITUDE OF MOKATTAM. 285

determined clock-error. After the return of Captain Browne from Egypt
the necessary comparisons for determination of these various differences
among the observers who took part in the longitude work were made.

To ascertain the personal differences in giving signals, the Greenwich
Chronograph was employed. Any two observers to be compared made
contacts alternately with a key such as was used in the actual longitude
work. The corresponding signals were registered on the Chronograph, the
times of contact being so symmetrically arranged that the means of all the
times referred for each observer to the same moment of absolute time.
Several sets of observations were made, the observers being interchanged in
various ways.

For the personal differences in receiving signals, a galvanometer, such as
was used in the longitude work, being mounted in a convenient position, an
assistant, placed in a different apartment, gave signals, which the various
observers noted, using the same clock. Several different sets of observations
were made.

A discussion of the whole of the comparisons made gave the following
results, the initials E, C, B, and H referring respectively to Mr. Ellis,
Mr. Criswick, Captain Browne, and Mr. Hunter. C is taken as the standard
of reference : —

Resulting difference
In giving signals. In receiving signals.

B S

C — E, + 0-068 — o'ogo

C — B, + o'o33 — o' io5

C — H, + o'o38 — 0-043

Thus E makes contact Os>068 earlier than C, but notes a signal Os>090 later
than C. These numbers refer to the giving and receiving of signals on the
land lines, and to giving on the submarine line, but not to receiving on the
submarine line.

In receiving longitude-signals on the cable the comparatively slow motion
of a beam of light was observed in two different ways. In one the first start
of the beam was observed, in the other the time of transit of the beam over a
provisional mark was observed. Some trials of the latter method made in the
month of August 1874, in the first instance with Mr. C. F. Varley's artificial
cable (kindly lent by him for experiment), and afterwards at Forth curno on

o o 2

286 TRANSIT OF VENUS, 1874. EGYPT.

the Eastern Telegraph Company's submarine cable, gave differences as
follows : —

Difference in receiving signals.
E - H.

At Koyal Observatory, Greenwich, by use of Varley's artificial cable —

1874, August i3 and i5 (direct comparison) o'oo

, , 1 5 and 1 8 (compared through B) +0*14

At Porthcurno, on the Eastern Telegraph Company's submarine cable —

1874, August 3o (compared through B) o'oo

, , 3o (direct comparison) — o'iz

No comparisons of the method of observing the first start of the beam
were made, as the use of this method was not proposed until the Egyptian
Expedition was about to leave England.

Now, as regards the actual corrections to be applied —

Mr. Criswick observed transits at Greenwich (or the transits of other
observers were reduced to his method), and exchanged signals on the English
land line with Mr. Ellis at Porthcumo.

Mr. Ellis at Porthcurno exchanged signals on the English land line with
Mr. Criswick at Greenwich, and on the submarine line with Mr. Hunter at
Alexandria.

Mr. Hunter at Alexandria exchanged signals on the Egyptian land line
with Captain Browne at Mokattam, and on the submarine line with Mr. Ellis
at Porthcurno.*

Captain Browne observed transits at Mokattam, and exchanged signals on
the Egyptian land line with Mr. Hunter at Alexandria.

The manner of giving signals was similar both in the land and cable work.
The personal equations of E and H thus disappear in the deduced longitude,
and C and B may be supposed to have been in direct connexion. By what
has preceded it will be seen that B makes contact in giving signals Os>033
earlier than C, the effect of which is to increase the east longitude of
Mokattam by the half of this quantity, because each operator gave signals
in one half only of the whole number of groups. Or the apparent longitude
requires a correction of — Os>016.

As regards the receipt of signals, it is to be remarked that E and H both
used, on the one hand a land line, and on the other hand a submarine line.

* Mr. Hunter also observed transits at Alexandria for determination of the longitude of
Alexandria, but this does not come into consideration here.

LONGITUDE OF MOKATTAM. 287

The signal received on the latter, as has been mentioned, is of a character
different to that received on the former ; it is therefore necessary to consider
separately each section of the work. In the first section C at Greenwich
exchanged signals with E at Porthcurno, using a land line. B receives land
signals O'090 later than C. The correction required by the longitude on
this account will be — Os'045. In the second section E at Porthcurno
exchanged signals with H at Alexandria, using the submarine line. There
is a little uncertainty as concerns the difference between E and H in receiving
cable signals, but according to the comparisons given on page 286 it would
appear that the difference in the method of observing the Varley signal was"
probably small. It will perhaps not be far from the truth to conclude
that for both methods of cable receiving there was no practical difference.
On this assumption no correction is required on account of receiving signals
in the second section. In the third section H at Alexandria exchanged
signals with B at Mokattam, using a land line. Now B receives land signals
Os> 105 later than C, and H Os*043 later than C, or B receives later than H
by O062. Consequently the correction required by the longitude will
be — Os<031. Or the total correction to be applied on account of personal
equation in receiving signals is —0s '07 6.

The correction for personal equation between C and B in the manner of
observing transits has now to be considered.

The transit instrument which was subsequently used at Mokattam was
mounted upon a pier of masonry in the south ground of the Koyal Observatory
at Greenwich, and was used by Captain Browne to determine the error of the
Sidereal Clock Dent 1914. The instrument was 185 feet east of the meridian
of the Transit-Circle. During the observations each day, the clock Dent 1914
was several times compared with the Sidereal Chronometer, sympathetic with
the Sidereal Standard Clock and Chronograph, by the intervention of a mean
time half-seconds chronometer. Captain Browne made observations of this
character on three nights before he went to Egypt, and on four nights after
his return. It is not considered necessary to give the details of these
observations, which were of the same character and quality as those made at
Mokattam.

Making a correction of Os>195 for the difference of longitude between the
two instruments, the results obtained were that Captain Browne (using the
small transit, and observing by eye and ear) made the Sidereal Standard

288 TRANSIT OF VENUS, 1874. EGYPT.

" clock slow " greater than that of the Greenwich standard observer (using
the Greenwich Transit Circle and Chronograph), as follows : —

1874, August 1 5, B — C = + o- ig5

21, o'iS

September 4,

0-405

July 6,

0-655

28,

o- ig5

3i,

o- 1 55

August 23,

O'O25

Mean

+ o'253

There appears to be no reason for rejecting the discordant result of July 6.
The observations on that night with both instruments were as numerous and
apparently as good as those on any other night.

We are now in a position to form the Concluded Longitude of
Mokattam : —

h m s

Apparent Longitude of Mokattam East of Greenwich, as

deduced from Table XI ........................ 2. 5. 6-58

Correction for personal equation between the Observers —

In giving signals, — os • o 1 6 "1

In receiving signals, — os'o76 /
Correction for personal equation between C and B in

the manner of obtaining star transits .............. — o'25

CONCLUDED LONGITUDE OF MOKATTAM, EAST OF

GREENWICH .................................. 2. 5. 6-24

W. E.
C. 0. B.

289

OBSERVATIONS OF THE EGRESS OF VENUS, 1874, DECEMBER 8,
AT MOKATTAM, NEAR CAIRO.

REPORT OF CAPTAIN C. ORDE BROWNE.

For practice in observation of the actual phenomena, as far as possible, a
working model had been brought out, similar to that previously used at
Greenwich (Plate V.). Mr. Hunter was in this respect at a disadvantage,
having his time much taken up by his preparations at Suez. He found time,
however, to practice a little on the model at Mokattam.

At Mokattam the work of preparation consisted in the trial and the
improvement of the working of the observing instruments, in the model
practice, and rehearsals of the operations at sunrise.

The De la Rue Equatorial had taken the place of the Altazimuth, and with
its clock and movable dome was in admirable working order.

Convenient observing seats and other arrangements, in accordance with the
directions issued by the Astronomer Royal, had been made.

MAHMOUD BEY, the Director of the Egyptian Government Observatory at
ABBASSEYAH, had repeatedly visited the Mokattam Station, and had watched
the phenomena of contact on the model ; and it may here be noticed that
Dr. AUWERS and M. DOLLEN, who visited the station at Mokattam, had
expressed their concurrence as to the phase of formation of the black drop, if
any were seen, which ought specially to be observed at Egress, namely, the
instant when the connexion which was forming assumed the same blackness
as the body of the planet.

During the first week in December there was much mist in the plain of
Cairo, and on the three mornings preceding the day of the transit the Sun
had been wholly invisible at Mokattam, except for about 20 minutes on one
occasion.

About sunset on December 8, by order of the KHEDIVE, a considerable body
of cavalry trotted up to the camp and picketed for the night. Infantry and
police subsequently arrived, and were posted on the following morning so as
to form a cordon round the station to prevent the approach of strangers.
During the night I obtained transits of stars through openings in the
clouds.

290 TRANSIT OF VENUS, 1874. EGYPT.

The wind continued in the S.W., and as the day began to dawn it was
evident that the sky was clearing from that quarter.

I set the two observing clocks, Dent 2009 and 2015, as nearly as possible
to true sidereal time, and then compared them with the transit-clock.

The " Lee Equatorial," with which I observed the Egress of Venus, was the
famous instrument by TULLEY, used by the late Admiral SMYTH, and fully
described by him in the first column of his Cycle of Celestial Objects. It was
purchased by the Government expressly for the Transit of Venus. At
Mokattam the polar axis was supported by massive structures of timber,
which rested upon the solid rock, but otherwise the instrument, accessories,
mounting, and driving-clock were in every respect the same as formerly, but
perhaps, rather the worse for wear. The hour-circle, which was also the
driving-circle, had been seriously distorted by a fall, and could not be
perfectly restored, but it answered its purpose well. The instrument was
protected by a large portable wooden hut constructed at Greenwich.

The tube of the telescope had been shortened a little to admit of the use of
a new solar diagonal reflector. Slow motion in Right Ascension to a limited
extent was effected by the slipping piece, described by Admiral SMYTH, which
carried the eye-piece at times out of the true centering. For the proper
equalisation of the illumination of the images of the double-image micro-
meter eye-piece it was imperative to have the latter fairly centered, which
was effected by trial, an assistant manipulating the driving-clock.

The double-image micrometer and solar reflector are represented in
Plate III. The power used was 158. The internal contact was observed
with a negative eye-piece of 212,* constructed to correct atmospheric
dispersion by tilting the eye-lens, but the definition being very good the
eye-lens was not disturbed.

The Sun rose behind a bank of cloud ; indeed, the sky was quite thick
towards the north and east horizon, but clear from the south-west up to the
zenith, and the clouds were breaking still further in the desired direction.
As the Sun rose higher the clouds became more broken. The intervals of
obscurity, however, were long and trying, especially the last, which began
eight minutes before internal contact, and lasted about five minutes.

As opportunity occured, I obtained the following measurements with the
micrometer for the diameter of the planet, and the distance between its
approaching limb and the limb of the Sun. Sometimes the images were
distorted by atmospheric tremor ; at others the definition was excellent. I

* Not 150, as stated in the Parliamentary Report, page 16.

BROWNE'S OBSERVATION OF EGRESS, AT MOKATTAM.

291

was struck by the exact resemblance to model practice. Some of the
measures were obtained without the intervention of the darkening wedge, but
it was generally required. My wife called aloud the seconds from the
Sidereal Clock Dent 2009, and recorded the observations : —

MICROMETER HEADINGS for the DOUBLE DIAMETER of VENUS.

rev.
26-841

26-85o
26-842
26-780
26-793

I7'i35

The zero, or reading for coincidence of images, was approximately 22r<0.
The smaller readings are in a negative, the larger in a positive, direction from
zero.

MICROMETER READINGS for the DISTANCE between the NEAR LIMBS of the SUN
and VENUS, along the Line of Centers.

Time by Dent
2009.

Micrometer
Headings.

Time by Dent
2009.

Micrometer
Headings.

h ni s

rev.

h m s

rev.

12.37.39

l6'35o

l3. 0. 24

l8-g22

38.5i

16-440

0.38

18-960

40. 8

16-712

I. 18

19-140

40. 21

i6'6ig

5.48

ig-655

40.42

16-667

48. 12

17-241

7.56

24'35i

46. 9

17-391

9- '4

24-168

47- 10

17-531

g. 3i

24-104

47.52

17-480

10. 6

24-028

48. 8

i7-55o

IO. 25

23-gi2

53.48

i8'25o*

10.41

23-874

54. 19

i8'23i

10. 5g

23-86o

55.45

1 8-436

11.48

23'6g3

56. 8

i8-5o6

12. 3

23-6i i

56. 39

i8'58g

12.35

23-437

57. 14

i8-5gi

12. 52

23-544

58.55

i8-845

13. 22

23-491

5g. 3i

18-891

14. 10

23-402

12. 5g. 53

18-834

i3. 14.34

23-343

Bad.

P P

292 TRANSIT OF VENUS, 1874. EGYPT.

The last cloud remained so long that I was afraid to leave the micrometer in
the telescope any longer, so I changed it for the negative eye-piece (212).
When the cloud opened I saw Venus very close to the limb, but no sort of
shadow of contact as yet. The shadow then began to appear, and I tried to
note the instant, but feared to interrupt my wife counting so near contact.
I tried to note some one instant, but could not, the shadow came so gradually.
The Sun becoming brighter, I saw a modified short ligament form, but did
not see the edges form into sharp curves and creep apart, as sometimes with
the model. Blackness gathered gradually, and at last came an instant when
it seemed to be as black as the planet, and to have no light crossing it. This
was at 13b. 22m. 25s. by the clock. As I continued to watch the ligament
(not moving my eye from the telescope), the Sun became suddenly brighter,
and I saw a sort of parting of the ligament by a very narrow white line,
which either became definite, or I perceived it to be definite, as the egress
went on. This appearance is represented in Figure 1, Plate X., but I cannot
draw the white line fine enough. The white line clung to the planet's edge,
and at last the planet was projecting beyond the Sun's limb, with the thread
of light clearly biting into the sky. (Figure 2, Plate X.)

I account for having seen the internal contact apparently completed by the
fact that there yet remained a film of cloud over the Sun, of which I was
made aware by the Sun becoming brighter just as the line appeared. I
watched this appearance until 13h. 24m. 25s. by the clock, when I concluded
that the white line was not of a passing character, but was due to atmosphere
or some other cause. Feeling disappointed at having, in consequence, lost
two of the most valuable minutes, I replaced the micrometer and took the
following measures of the distance between the cusps and of the diameter of
Venus, in the direction parallel to the line of cusps, the latter being continued
until the planet was half emerged : —

MlCROMETEE READINGS for DISTANCE of CuSPS.

Time by Dent 2009. Micrometer Headings.

h m

. 25. 5g 26-249

26.26 25'40I

26. 5o 25'43g

27. 10 25'63o
27.35 25-802

Time by Dent 2009. Micrometer Readings.

h m

i3.27.53 25-g3o

28. 1 8 26-021
28.44 26-104

29. 5 26-145
29. 23 26-258

BROWNE'S OBSERVATION OF EGRESS, AT MOKATTAM. 293

MICROMETER EEADINGS for the DOUBLE DIAMETER of VENUS.

rev.

26-971
26-966
26-998
26-995
26-987

16-927

rev.

i6-gg3

17-076 bad.

17-013

17-065

17-081

1 7-005

17-068

The EXTERNAL CONTACT, as far as I could judge, took place at 13h. 50m. 333.
The clocks were then again compared with the transit.

The transit being over, the three telescopes were placed so as to observe
the model simultaneously. The management of the mirror for illuminating
the model required considerable delicacy, so that Mr. Newton and I had to
manipulate it alternately. Our comparison was therefore made through
Miss Newton. Ten comparisons were made in each case ; at the conclusion
of which it was found that Mr. Newton recorded contact 2S>5, and
Miss Newton Os-8, later than I did.

If these corrections be applied to our recorded times of the actual internal
contact the latter would all be brought within the same second of time. The
application of such a correction, however, is a matter affecting other stations,
and cannot be done here.

Speaking generally of the contact as seen at Mokattam it may be noticed,
by reference to the individual accounts, that in every case the gradual
formation of a black drop was perceived a little before contact, a shadow being
first seen between Venus and the Sun's limb, which deepened gradually until
a blackness nearly, if not quite, as dark as the body of the placet seemed to
flow over it. This was the instant noted as contact. Almost directly after
this each observer was perplexed by detecting light crossing the ligament,
which quickly became definite, till it shone out as a sharply defined silver
thread, which made any estimate of geometrical contact impossible.

C. ORDE BROWNE.

pp 2

294

TRANSIT OF VENUS, 1874. EGYPT.

COMPARISONS of the EQUATORIAL SIDEREAL CLOCK DENT 2009 with the TRANSIT
CLOCK by the intervention of the SOLAR CHRONOMETER FRODSHAM
and inferred ERRORS and RATE of No. -2009.

1874.

Time by
Transit Clock
at Comparison.

Chronometer Time of
comparison with

Time by Clock
No. 2009 at
Comparison.

No. 2009 slow
on Sidereal
Time.

No. 2009
Hourly Kate.

Transit Clock.

No. 2009.

h m s

h m s

h m s

h m s

s

s

Dec. 8

g. 53. 36-o

4. 42. 5o-o

4.53. 5-o

10. 4. 2TO

— 0-54

g. 56. 40-0

4.45.53-5

4. 56. 3'5

10. 7. 2O'0

— O'55

14. l5. I2'O

g. 3. 43-0

8. 44. ig-5

i3. 56. 14-0

- 0-82

— 0'08

14. 1 8. 1 5-o

q. 6. 45'5

8. 47. 2o'o

i3. 5g. i5'o

-o-83

14. 21. 17-0

9- 9-47'°

8. 5o. 25-5

14. 2.21-0

— 0-82

COMPARISONS of the SIDEREAL CLOCK DENT 2015 with the TRANSIT CLOCK by
the intervention of the SOLAR CHRONOMETER FRODSHAM -^/Vs, and
inferred ERRORS and RATE of No. 2015.

Chronometer Time of

1874.

Time by
Transit Clock
at Comparison.

comparison with

Time by Clock
No. 2015 at
Comparison.

No. 2015 slow
on Sidereal
Time.

No. 2015
Hourly Rate.

Transit Clock.

No. 2015.

h in s

h m s

h m s

h m s

s

s

Dec. 8

g. 53. 36-o

4. 42. 5o-o

5. 12. 26-0

IO. 23. 45'O

— 0-34

g. 56. 40*0

4. 45. 53'5

5. 1 5. 34-5

10. 26. 54-0

-o-33

+ 0-16

14. 1 5. I2'O

g. 3. 43-0

8.56.42-5

14. 8.38-0

-f 0'22

14. 1 8. 1 5-o

g. 6. 40-5

8. 5g. 34-0

14. ii. 3o-o

+ o-ig

NEWTON'S OBSERVATION OF EGRESS, AT MOKATTAM. 295

OBSERVATION of the EGRESS of VENUS, 1874, December 8, by

Mr. F. M. NEWTON.

Mr. Newton was indebted to the kindness of Mr. WARREN DE LA RUE for
the use of a fine Equatorial by Dallmeyer of 4| inches aperture, driven by
clockwork, and fitted with a solar diagonal reflecting prism. This instru-
ment was mounted in the hut with revolving roof sent from England for the
Altazimuth. The Secondary Sidereal Clock Dent 2015 was also mounted
within the hut, and was used by Mr. Newton ; its comparisons with the
transit-clock are given on the preceding page.

For the observation of the Internal contact, Miss Newton used an achro-
matic of 3 inches aperture, the property of her brother, temporarily mounted
on a rough equatorial stand, constructed of wood. The Sun was viewed
directly, that is, without the intervention of a reflector.

Mr. Newton writes to the Astronomer Royal from Mokattam Heights, 1874,
December 7 : —

" I take the liberty of sending you a drawing of Venus [Plate X., Fig. 6]
taken with Mr. De la Rue's exquisite telescope on Saturday, 5th, at lh, showing

that the crescent is now considerably more than a semicircle.*

I thought it would be well to note, before the transit occurs, an appearance
which seems to point to an atmosphere on Venus, which may make the
phasnomena of the black drop in the real transit rather different from those in
the Model transit. The power used in making the drawing was 300 diameters."

" Account of Impressions during the Egress of Venus, 1874, December 8.

" The clouds broke at 12h. 9m. 4s. I was using a reflecting solar eye-piece
with power 145, and saw Venus at intervals. Finding the clouds continuous,
I put in an eye-piece magnifying only 52 diameters, and after observing with
it a few minutes, I removed the dark glass and observed the image projected
on a sheet of paper, in which the diameter of Venus was about f ths of an
inch. I thought that very good observations could be made in this manner. f

" The weather improving I replaced the eye-piece of 145. Light clouds
obscured the Sun at intervals, and the limb was " boiling " considerably.
About 10 minutes before contact a thick cloud swept over the Sun, completely
obscuring it. This, happily, cleared off about 10 seconds before contact,
leaving the Sun fairly but not well defined, owing to a slight haze following
the cloud. The contact was observed through this at 13h. 22m. 20S>7 by the

* In Mr. Newton's original sketch the bright cusps are 143° apart ; in other words, the crescent is
37° more than a semicircle.

f This method was employed by the members of the Mexican Expedition to Japan.

296 TRANSIT OF VENUS, 1874. EGYPT.

Sidereal Clock. Very little ligament. Having written down the seconds
I looked at the clock for the minutes.

" On returning to the telescope I at once observed a thin line of light
surrounding Venus' limb at that part where contact had just taken place.
My first idea was that contact had not really occurred, but I almost imme-
diately saw the line of light projecting beyond the Sun distinctly into the sky.
(Figure 3, Plate X.) This appearance was permanent as long as I kept my
eye to the telescope — some 80 to 100 seconds. I then removed the eye-piece
of 145, and replaced it with one of 52 diameters, with which I continued to
observe Venus until external contact.

li m s

" Estimated passage of Venus' center at 13. 36. 30
" Last External contact 13.51. 0

" My sister was present during the last observation, and observed it with
me.

"P. M. NEWTON."

Miss NEWTON writes : —

" I noted Internal contact at 8h. 10m. 35s. by Frodsham's Chronometer.
Appearance much the same as in the Model, but the ligament less sharply
defined. (Fig. 4, Plate X.) In a few seconds the ligament began to grow paler,
and at llm. 30s. seemed almost to disappear (Fig. 5, Plate X.), so that I
thought I must have been mistaken in my first observation of contact. Venus
appeared to touch the limb of the Sun without any ligament at 12m. 0s.

" At 8h. 20m. 50s. the planet's disc began to assume the black drop
appearance. At 26m. 30s. it appeared as a semicircle.

" I observed external contact by means of the image projected by
Mr. De la Hue's telescope at 13h. 50m. 50s. by the clock Dent 2015.

" E. M. NEWTON."

The comparisons of the Solar Chronometer Frodsham ^-Q-g* with the transit
clock given on page 294 yield the following errors of the chronometer : —

Local Mean
Time.

Frod. sjfef Slow
on L. M. T.

Hourly Losing
Kate.

h m

8

i

1 874? December

3, 16.43

+ 3i.gi

16.46

21. 4

+ 3i.gi
+ 32. i3

-t- o'o5

21. 7

+ 32. 14

* In the Parliamentary Report this number of the chronometer was erroneously given as 1752.

Transit of Venus 1814 Dec. 8.
Diagrams relating to the Egress of Venus as observed at Mokaltam..

Fig.1.

Copt. Bimrne.

Tig 2.

Copt. Browne.

Fig. 3.

r Newton*

Fig. 5.

Newton*.

Eg.6.

Fig.*.

Miss Nekton.

MT Newton-.

DARGCKntl.D.lnH.22 BlO'Cmo ST CovfftT

FORMATION OF EQUATIONS OF DISTANCE OF CENTERS, FOR MOKATTAM. 297

EQUATIONS RESULTING FROM THE MICROMETRICAL OBSERVATIONS AT MOKATTAM.

From the first series of Captain Browne's micrometric measures of the
double diameter of the planet are obtained the quantities —

rev.

Diameter of Venus 4' 837

Zero-reading 2 1 • 972

From the final series are obtained —

r

Diameter of Venus 4 '977

Zero-reading 22 • oo5

The mean of the two determinations of the diameter, which are not in very
close agreement, is 4r-907, and taking the tabular diameter as 62"'84, the
value of one revolution of the micrometer-screw is —

1 2"-8o6 + 0-408 S r,

where 8 r is the correction required to the tabular semidiameter, to be deter-
mined hereafter.

It is essential in using the double-image micrometer of this construction
that the zero, or reading corresponding to the coincidence of the images,
be determined with the micrometer-screw in the same position angle, with
regard to its rotation around the axis of the micrometer itself, as it had
during the measures. There are no means of knowing the position of the
screw during the first series of measures of double diameters, hence the zero-
reading obtained from them should not be employed.

The Zero proper to the measures of the distance of limbs is obtained by
comparing the measures themselves, before and after the change from the
negative to the positive side, with the computed tabular quantities. In this
way, using the five readings on each side of zero, between 12h. 59m. 53s. and
13h. 10™. 25s., the zero 22r>152 is obtained, and has been applied to. all the
measures in order to obtain the observed distance of limbs in terms of the
revolution of the screw. This has been converted into arc by using the value
of one revolution given above.

For the Cusp measures the zero proper to employ is that obtained from
the final series of double-diameter measures, viz., 22rev>005, the micrometer
not having been rotated in the interim. It will be seen that the last five or
six cusp measures are entitled to but little weight, they having been observed
more than five minutes after contact.

298

TRANSIT OF VENUS, 1874. EGYPT.

The Equations are then formed in the manner described in the Honolulu
section, page 47, adopting the same notation and taking the tabular semidia-
meter of the Sun 16'. 16"'82. The mean of the 23 measures on the negative
side had been considered equal in weight to the mean of the 14 measures on
the positive side, by which the zero is eliminated.

For the Telescopic Contact at Egress, assuming the Latitude 30°. 1'. 46" '4 N.,
Longitude 2h. 5m. 6s -58 East of Greenwich, we have :—

Observer.

Recorded
Clock Time.

Mokattam
Sidereal Time.

Greenwich
Sidereal Time.

Local Tabular
Distance of
Centers of the
Sun and Venus.

INTERNAL CONTACT.

F. M. Newton . ,

h m I
l3. 22. 20'7

8. 10.35-

l3. 22. 25'

8.12. o-

h m s

i3. 22. 20-90

l3. 22. 23'22
l3. 22. 24-35

i3. 23.48-45

h m s
11. 17. I4-32
II. 17. 16-64
II. 17. 17-77

ii. 18. 41 -87

/ /;

i5. 41 -34
i5. 41 -42
1 5. 41 "45
i5. 44'3i

E. M. Newton

Browne

E. M. Newton

EXTERNAL CONTACT.

Browne

i3. 5o. 33-
1 3. 5o. 5o'
i3. 5i. o'

i3. 5o. 32'32
1 3. 5o. 5o"3o
i3.5i. o'3o

1 1. 46. 25-74
n. 46. 43-72
11. 45. 53-72

16. 43-90
1 6. 44-64
1 6. 40 'o3

E. M. Newton

F. M. Newton

EQUATIONS OF DISTANCE OF CENTERS, FOR MOKATTAM.

299

i. t,

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*o «o

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of Centers of the
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52 ~l~

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300

TRANSIT OF VENUS, 1874. EGYPT.

I

&

r*3

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H

<D

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II

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w d

02 S

ll

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e of Centers of th<
d Mean Solar Par

i

96o85N.P.D. -

o

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• 1 1 ] M i , i AA

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nferred Distance
of
Near Limbs.

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0

EQUATIONS OF DISTANCE OF CENTERS, FOR MOKATTAM. 301

COLLECTED EQUATIONS, FROM ALL OBSERVATIONS AT MOKATTAM.

The observations at Mokattam yield therefore the following FINAL
EQUATIONS : —

(1) The Micrometric Measures of distance of Limbs —

o = 4"-g3 + "-i85i n + -1678 8 E.A. + -9821 8 N.P.D. — "-0289 8 t + 8 R — 2-i83 8 r ;

(2) Mr. Newton's Internal Contact —

o = 4"-o6 + "-2014 n + -2434 8 E.A. + -9646 8 N.P.D. — "-0342 8 t + 8 R — 8 r;

(3) Miss Newton's Internal Contact—

o = 3"-g8 + "-2014 n + -2436 8 R.A. + -9645 8 N.P.D. — "-0342 8 t + & R — 8 r ;

(4) Captain Browne's Internal Contact —

o = 3"-g5 + "-2oi5 n + -2436 8 E.A. + -9646 8 N.P.D. — "-0342 8 t + 8 E — 8 r;

(5) The Micrometric Measures of distance of Cusps —

o = 4"-36 + "-2044 n + -2899 8 E.A. + -g5g5 8 N.P.D. — "-o353 8 t + 8 E — o'66g 8 r;

(6) Captain Browne's External Contact —

o = 4"-34 + "'2149 n + -3325 8 E.A. + -g328 8 N.P.D. — "-0402 8 < + 8 R + 8 r ;

(7) Miss Newton's External Contact —

o = 3"'6o + "-2149 n + -3334 8 E.A. + ^24 8 N.P.D. — "-0402 8 t + 8 E + 8 r ;

(8) Mr. Newton's External Contact —

o = 3"-2i + "-2i5o n + -333g 8 E.A. + -g322 8 N.P.D. — "-0402 8 t + 8 E + 8 r.

On page 288 the final longitude of Mokattam is stated to be 2h. 5m. 6s -24, E.,
hence the above Equations require the correction obtained by making 8 t
= + 0s -34. It will be understood that 8 R.A. and 3 N.P.D. are the cor-
rections required to Tabular R.A. and N.P.D. of Venus in seconds of arc
referred to the center of the Sun.

After his return to England, Captain Browne made a determination of the
value of a revolution of the screw of his double-image micrometer. The
telescope was laid horizontally upon two tripod supports, and directed upon
the transit instrument which had been used at Mokattam. A fixed web had
been inserted in the transit-instrument in addition to the five webs moved by
the micrometer-screw. In the focus of the eye-lens of the double-image
micrometer were inserted two webs crossed. The reticule of the transit being
sharply defined in the field of the double-image micrometer, the distance of
the fixed web from the center movable web was measured by bringing their
images into coincidence with the screw of the double-image micrometer, near
the center of the field as defined by the crossed webs. In this manner,

QQ 2

302 TRANSIT OF VENUS, 1874. EGYPT.

between 1875, May 21 and June 2, some 60 comparisons were made of the
relative values of revolutions of the two screws, using different parts of the
screws, all showing a very close agreement. The half and quarter revolutions
were also tested. It was found that 4'320 revolutions of the screw of the
double-image micrometer were equivalent to one revolution of the screw of
the transit-micrometer. The value of the latter had been very carefully
determined at Mokattam to be 56"'43 ; re-determined at Greenwich, 56"-35
was obtained. Adopting 56"-40, the value of one revolution of the double-
image screw is 13"'06.

The measured semidiameters of Venus in transit were —

2^-419 and 2reT'488,

corresponding to —

3i"-59 and 32"'5o.

The mean of the two gives —

8 r = + -o"62,

which, although not very trustworthy, agrees very closely with the value
obtained with telescopes of nearly the same aperture at Honolulu and Roorkee.

Time of Internal Contact at Molcattam inferred from the Cusp-Measures.

Taking 8 r = + 0"'62, as above, the Greenwich Sidereal time of internal
contact inferred from the first five cusp-measures is —

h m a

ii. 17. 9-2, weight 9,
11.16.57-8, „ 7,
11.17.14-5, „ 6,
ii. 17. 7-1, „ 5,
11. 1 6. 56-2, „ 4.

The mean with the weights assigned is —

5s-6,

which is from 10 to 12 seconds earlier than the telescopic contacts, proving
that the cusp-measure is too great, as was found at Honolulu and Roorkee.

G. L. T.

303

MERIDIONAL AND ALTAZIMUTH
OBSERVATIONS

AT

MOKATTAM,

IN TABULAR ARRANGEMENT.

304

TRANSIT OF VENUS, 1874. EGYPT.

TABLE XIII. — LEVEL ERROR of the TRANSIT INSTRUMENT at MOKATTAM,

determined by SPIRIT-LEVEL.

[The sign + indicates that the East Pivot is low.]

Day.

Observer.

Sidereal
Time
of Level
Deter-
mination.

Position of Head
of Micrometer-
Screw.

Level Error
corrected
for
Inequality
of Pivots.

Day.

Observer.

Sidereal
Time
of Level
Deter-
mination.

Position of Head
of Micrometer-
Screw.

Level Error
corrected
for
Inequality
of Pivots.

1874.
Nov. 3

B
B
B

h m

23. 10
I. 0
I. 20

W
W
E

+ 179
-f- 5'oo
+ 5-26

1874.
Nov. 1 5

B
B

B

h m

2. 5
3. 0
4.3o

E
W
W

- 1-82
- 3-34
— o-i3

4

B

23. 0

W

- 2-83

B
B

5. 10
6. 20

W
E

— °'49

N

I. 0

- °'49

B

6. 5o

W

— o'i6

N

I. 20

+ 1-42

B

8.3o

W

5

N

I. 0

W

- 1-54

N

I. 40

E

— i '04

16

B

i.3o

W

— o-3i

B

1.55

E

+ 2-32

6

N

i. 5

W

- 7-27

N

i.3o

E

- 4'4°

18

B

23. o

E

+ 0-34

7

B

N

N

23. 3o

I. O

i.3o

W
W

E

— o-52
+ 10-28

+ 979

B

N
N

0. O
I. 0
1.25

W
W
E

— o-qi
+ O'2O

+ 1-45

9

B

3. o

W

'9

B

B

o. o

I. O

W
W

+ ''97
+ i'43

10

B

20. 3o

W

— o-i3

B

1. 20

E

+ 2-38

B

B

23. 5o
i. 5

W
W

- o-58

20

B
B

I. 0

1.36

E
W

- 278

B

i. 3d

E

+ r57

n

B
B

I. 0

i.3o

W

E

- 1-24
+ o'3i

21

B
B

n

0. 0
I. 0
1.25

W

vv

E

+ 1-64

+ 4-64
+ 5'5o

12

B

N
N

o. 1 6

I. 0

i. 20

W
W
E

- 2-32

— 0-79

— 0-35

B
B
B
B

2.45

4. io
7.i5

IO. O

E
W
W
W

+ 478
+ 473
+ i '04

— 2 'O2

i3

B
B
B

23. 45
I. IO

i. i5

W
W

E

+ 0-17
+ r85

+ 4-09

22

B
B
B

23. 3o

2. 5
2. 13

W

W
E

+ i '4°
+ 5-48
+ 5-26

'4

B
B

23. 3o

I. O

W
W

— 0-40
+ i '04

B
B

4. io
5. 40

E
E

— 0-26

— i-58

B
B
B

1.25

4.35

7.30

E
E
E

— 1-28
- 2-63

— 2'l5

23

N
N

1. 0

i.3o

W
E

- 2-41
+ 0-46

i5

B
B

21. 20

23. 5

E
E

— 1-04
- 2-36

24

N
N

I. O
2. 15

W
E

— 3-32

LEVEL ERROR OF THE TRANSIT INSTRUMENT, AT MOKATTAM.

305

"=> t.

"S •"

o) s

Sidereal

Ho
a

Level Error

Sidereal

HI

Level Error

Time

"*- £

corrected

Time

•

corrected

Day.

^

of Level

° .2

for

Day.

lj

of Level

"8 |

for

B

Deter-

0 ^ «

Inequality

Deter-

0^0

Inequality

B

mination.

'5 o

of Pivots.

C
B

mination.

'** 0

of Pivots.

J8

'§ 0 O2

CD
£

'|°5 co

0

PH

O

PH

1874.

li m

»

1874.

h m

//

Nov. 25

B

6. i5

E

+ ri5

Dec. 7

B

23.25

W

— 0^46

N

I. 0

W

— 4-87

B

O. 10

W

— 0-64

B

I. 0

E

— I'I2

26

N

I. O

W

+ 071

B

3. 10

E

+ o-58

B

3.35

W

+ 2-48

27

N

O. IO

W

— 0-88

N

o. 5o

W

+ o-23

8

B

23. 1 5

W

— 0-43

N

1.27

E

+ 0-46

B

23. 40

W

- o-55

B

o. 10

E

— o-o5

28

N

o. 1 5

W

- 376

B

o. 5o

E

+ 0-82

N

i. 40

E

- I73

B

5.55

E

— 0-29

N

3. 25

W

- 4-21

B

7.40

E

+ I'OO

B

10. 5o

E

— 0*04

3o

N

I. 0

W.

— 3'22

N

i. 35

E

— 0-62

9

B

o. 1 5

E

+ °'97

N

3.io

E

— i-58

B

I. O

E

— 0'52

N

4. o

W

— 2*92

B

1.36

W

— ro6

B

II. O

W

— 4-36

10

B

5.3o

W

— 2'05

Dec. i

B

o. 3o

W

— 0-37

B

6. 20

E

+ 0-40

B

I. 20

E

+ 3-i3

B

7.40

E

+ 2-17

2

B

o. 5o

E

— rig

1 1

B

o. 8

E

- i'79

B

1. 3d

W

— 0-64

B

1.55

E

- 2-24

12

N

I. 0

W

— o-85

N

I. 25

E

+ 0-25

3

B

o. 5o

E

— 1-46

N

2. 3o

W

+ o-53

B

I. 20

W

— 2'O5

B

1.55

E

+ o-85

'4

B

o. 10

W

+ 2-06

B

I. 0

E

+ 0-64

4.

B

0. 10

E

— 0-29

B

1.25

W

+ 0-08

B

I. O

E

— 2'21

B

4. 20

W

+ 2-24

B

I. So

W

— 3-3 1

B

5. i5

E

+ 3-i3

B

4. 1 5

W

— 0-6 1

B

5. 40

E

+ 1-66

B

4.45

E

- 270

B

5. i5

W

+ 6-38

i5

B

o. 18

E

+ 0-52

B

i. 5

W

- o-3 1

5

B

23. 5o

W

- 2-38

B

i.3o

E

+ i'3g

•

B

o. 40

E

+ 0-07

B

1.42

W

+ 0-17

B

i. 1 1

E

+ I'og

B

i.3o

W

- 1-24

16

B

23. 28

W

— o'gi

B

2. 10

W

+ o-i3

B

4. 5

E

— 2'l5

21

B

o. 3o

W

— o-g4

B

4.42

W

— 7'6o

B

i. 20

E

— 0-80

306

TRANSIT OF VENUS, 1874. EGYPT.

TABLE XIV. — COLLIMATION of the TRANSIT INSTRUMENT at MOKATTAM, deter-
mined by OBSERVATIONS of a CIRCUMPOLAR STAR, with reversed POSITIONS
of the TRANSIT Axis.

1874.

Approximate Local
Mean Time.

Star.

Reading of the Micrometer for coincidence
of Center Wire with the Optic Axis.

Observed.

Adopted.

October 3o
3i

November 2
3

4
5
6

7

10
12

i3

•4
i5

> >

18
»9

20
21
23

24

27
28

3o

December 2
3

4
5

9

12

'4

15

21

h in

10. 3g
io.35

ic. 27

10. 23

10. 19
10. i5

10. I I

10. 7
9. 55
9- 5 1
9-47
9-44
9.40
14.34
i5. 3

9-H

9. 20
9. 16
9.12

9- 4
9. o
8.48
8. 45
8.37

8. 29
8.25

8.21

8.17
8. i
7-49
7-41
7.37
7. 14

Polaris

r

19-789
•722

•676

•78i
•698
•768
•701
•787

•679
•691

•627
•643

•655

•699
•678

•679
•692
•677
•699
•672
•674
•698
•683
•703

•678
•688
•663
•709
•682
•685
•704
•674
19-686

r

»9'74°

» >

) )
» >
> >
> )
J >

19-740
19-668
> j
5 >
j »
» >
? )
» >
19-668
ig-683
j >
? )
» >
ig-683
iq'6go
» »
j >

> >
» >

» 9
» 1

) »
) )
) J
9 9

i g • 690

8 Ursae Mm. S.P.
Cephei 5i

Polaris

MERIDIONAL TRANSITS, MOKATTAM.

307

TABLE XV. — AZIMUTH ERROR of the TRANSIT INSTRUMENT at MOKATTAM.

[The sign + signifies that the optic axis points East of South.]

Day.

Stars employed.

Apparent
Error
of Azimuth.

Day.

1

Stars employed.

Apparent
Error
of Azimuth.

.874.

//

1874.

//

Nov. 3

Polaris and c Piscium.

+ 10-83

Nov. 24

Polaris and ya Ceti . . .

— 4-28

4

, K Pisciiun.

+ 11*91

2?

„ y Piscium.

- 4-66

5

, v Piscium .

+ 13-40

28

„ i) Piscium .

— 4-62

6

, o, Eridani

+ ig-5i

3o

,, a Ceti. . . .

— 7-o5

7

, v Piscium.

+ 20'5 1

10

, < Piscium.

+ 57-87*

Dec. 2

„ i\ Piscium.

- 7-86

1 1

, y Piscium .

+ 4-92

3

„ 11 Piscium.

— 12-48

12

, 1 2 Ceti . . .

+ 6-01

4

„ y Piscium.

— u -02

i3

,, 5j Piscium.

+ 7'5i

5

,, i) Piscium.

— 14-90

14

„ y Piscium .

+ 8-26

8

S Ursa) Minoris S.P.

i5

8 Ursa; Minoris S.P.

and Cephei 5 1

— I 1"O7

und Cephei 5i

+ 7'33

Polaris and v Piscium.

/
— 1 3"O7

18

Polaris and i Ceti ....

I / "*»

- 5-77

12

,, y Piscium.

/

-13-86

«9

„ i Piscium.

- 4-67

H

,, y Piscium .

— 15-71

20

„ o Piscium.

- 6-83

15

„ £ Piscium .

— 16-45

21

„ v Piscium .

- 7-96

21

„ 20 Ceti. . .

-i6-56

23

„ n Piscium.

— 4-60

* The azimuth adjustment was altered before and after the observations on November 10.

TABLE XVI. — MERIDIONAL TRANSITS observed at MOKATTAM, near CAIRO.

1874.

Observer.

Position of
Micrometer Head.

Star and (Number of
Wires when less than Five).

Mean observed
Clock Time
of Transit over
the Center Wire.

Seconds
of True
Transit
over the

Meridian.

Star's
Assumed
Apparent
K.A.

Clock
apparently
Slow.

Nov. 1 4

jj

W

h m s

23. 52. 38-84

s
3g*33

3

53*32

•

a Andromeda?

O. I. 4O'Q7

41*30

55*38

14/08

o. 6. 33-28

33*72

4.7-76

H*O4.

i Ceti

O. 12. 48"Q2

4Q*56

3*46

l3*9O

44 Piscium ,

o. 18. 45-10

4.0*64.

59*6O

I 3*q6

e Andromeda

O. 3l. 42*54.

42-S6

66-98

H'l 2

fi Ceti

O. 37. 4*44.

5-17

I9*O8

l3*9I

8 Piscium

O. 41. 57*27

57-76

1 178

I 4/O2

20 Ceti

o. 46. 22-64.

23*2 I

37*17

i3*c)6

/A Andromeda)

O. 4Q. 3j.'64

d/rSq

48*08

I4/OQ

Polaris, 21 '"240

I. Q. O'7O

SQ'OA.

1 6* 1 7

1 6-63

K

Polaris, 2 ir' 240

I . I 7. 37'4.O

4.*73

16*1 7

I I '4.4.

y Pifcium

I . 34. 4 I *Q3

A I *7Q

i3*g6

o Piscium

i . 33. 34*04

33*87

4.7*77

+ l3'qo

November 14. The transit micrometer was set at 19'' 740 for the clock stars.

R R

308

TRANSIT OF VENUS, 1874. EGYPT.

1874.

Observer.

Position of
Micrometer Head. 1

Star and (Number of
Wires when less than Five).

Mean observed
Clock Time
of Transit over
the Center Wire.

Seconds
of True
Transit
over the
Meridian.

Star's
Assumed
Apparent
E.A.

Clock
apparently
Slow.

Nov . 1 4

B

E

<>! Eridani

h m B

4. 5. 32'i8

s

32-o8

8
46*3l

5
+ I4-23

y Tauri

4. 12. 27"44

27-1 1

4-1*14.

I4'o3

4. 21. 5'6o

5-23

iq'36

1 4" 1 3

4. 28. 3i-6i

3r27

46*20

i3 g3

a Canis Minoris

7. 32. 3i'25

3ro5

45' 24

H'IQ

ft Geminorum

7.37. 26-00

25-53

3qp65

H'l 2

Nov. 1 5

B

E

21. 24. 4.3' 46

43-40

57-62

I 4*22

£ Aquarii

21. 2g. 5O"62

5o-57

4-78

H'l I

§ Capricorni

21. 3g. 53-21

53-23

7-48

H'25

21. 47. 7'64

7-28

21 "52

I 4*24.

a, Aquarii

21. 5g. 6-72

6-63

2O'ql

14-28

a Pegasi ,

22. 58. 17-50

17-17

3i-5i

14' 04

y Piscium

23. 10. 26-53

26-32

40*61

I4*2o

K Piscium

23. 20. 17-00

16-80

3i'o7

14*27

» Piscium

23.33. 16-86

16-64

3o'q2

14-28

23. 42. io"32

io-38

24-82

H'AA

23. 62. 3q"24

3q'oi

53-32

I 4*3 1

2 Ceti

23. 57. 5'qq

5-q6

2O"I 1

1 4* 1 5

O. I. 41'72

4i'23

55-37

H'14.

o. 6. 33-8o

33-48

47-75

H*27

o. 18. 45-68

45-38

So'So

H*2I

O. 24. 25'32

25-18

3q'5o

14*32

e Andromedas

o. 3i. 43*24

42-74

56-q7

H*23

jS Ceti

o. 3?. 4-86

4-84

iq'O7

14*23

i. 5q. 54-02

53-65

7'85

H*2O

£3 Ceti

2. 21. 16-90

16-68

3rio

H*42

"W

3. 1 3. 46-42

46-65

I'OO

14*35

o Tauri

3. 17.50-86

5i-i8

5-64

H*46

/Tauri

3. 23. 44'OO

44"3o

58-71

I4.'4I

e Eridani <

3. 26.48-25

48-74

3-04

H*3o

1 1 Tauri

3.34. 4-14

4-33

18-70

i4*3y

S Eridani

3.37. r38

1-87

16-18

1 4*3 1

YI Tauri

3. 3q. 4Q"oq

4943o

3-63

14*33

Aj Tauri

3.57. 4*14

4-36

i8-6q

14-33

4. 1.38-71

38-g6

53-41

14-45

oj Eridani

4. 5.3i-54

3rgg

46-33

H'34

4.. 12. 26*4.6

26-73

4.1*16

14*43

£ Tauri

5. 1 8. 9-07

q-34

23-67

14-33

5. 26. 58-53

Sg'io

13-55

I4"3a

5. 2Q. 37'82

38-3o

52-5i

I4'2I

5. 41. 35 -oo

35-64

5o-oo

14-36

a Orionis

5. 48. 0-78

io'ig

24*46

H*27

E

8 Ursse Minoris S.P., i6r>74O
8 Ursse Minoris S.P., i6r-74o
Cephei 5 1 , 1 6r • 740

6. 8.55-5o
6. 1 5. ii'3o
6. 37. 32*40

g-65

12*19
12-57

26-68
26-68
28-61

17-03
14-49

l6'O4

W

Cephei 5i} i6r'74O

6. 45. io-3o

i3-io

28-61

+ 1 5-5 1

The Azimuth Error, November 15, H- 7" '33 for all the observations.
November 15. The transit micrometer was set at K)r"j4O for all clock stars.

MERIDIONAL TRANSITS, MOKATTAM.

309

1874.

Observer.

Position of
Micrometer Head. 1

Star and (Number of
Wires when less than Five).

Mean observed
Clock Time
of Transit over
the Center Wire.

Seconds
of True
Transit
over the
Meridian.

Star's
Assumed
Apparent
R.A.

Clock
apparently
Slow.

Nov. 1 5

B

W

y Canis Majoris

h m s

6. 57. 51*29

B

5 1*90

s
6-28

s

+ 14*38

7. 5. 56*66

57'o3

I I '4Q

H'46

8 Geminorum

7. 12. 2A.'A.S

24'8l

3q'3o

I4*4q

y Cancri

8. 35. 47*64

48-26

2"5l

14*25

£ Hydra)

8. 3q. 53-q6

54-65

8-78

1 4' 1 3

Nov. 2 1

B

W

y1 Peffasi .

o. 6. 3o*36

3O'O2

47'7I

I7'iq

j Ceti

o. 1 2. 46-34

46-28

3'4.I

17*l3

44 Pisciurn

o. 1 8. 42^08

42'l3

5Q*55

17*22

1 2 Ceti

O. 23. 22'l6

22'l5

3o*4.6

1 7'3 1

€ Andvomedsc

o. 3i. 3g'36

3Q-Q2

56-q3

17-01

o. 41 . 54*52

54-81

I 1*74-

i6*o3

o. 56. g'83

IO'I 2

27*4.1

I7*2Q

Polaris (2), 2or'ggo

i. o. 5*oo

58-o8

I 2*71

1 4.* 63

K

i . 16. 34*70

53' I O

I 2'7I

IQ"6l

i . 34. 38*g3

38-82

55*74

l6'Q2

o Tauri

3. 17. 48*77

48-65

5'6q

17*04

T Arietis

3. 1 3. 44' i o

4.4/OQ

I'o5

16*06

f Tauri

3. 23. 41*92

41-82

68-77

l6*q5

e Eridani

3. 26. 46-4.4.

4.6*10

3'OQ

.» y^

l6*qq

1 1 Tauri

3.33. 172

1*77

18-77

17*00

i\ Tauri

3. 3q. 46-66

46-70

3-70

17*00

7j Eridani

3. 5i. 55-84

55-46

i2'5o

17*04

Aj Tauri

3.57. 1-68

i'6g

18-77

17-08

BJ Tauri

4. I. 36"4Q

36-46

53'4o

I7*o3

oj Eridani

4. 5. 2Q"52

2Q-24

^^y
40*40

17*16

\V

f Tauri

4. 21. I"82

2'25

10-47

17*22

a Tauri

4. 28. 27'72

28-1 I

45*32

17*21

1* Eridani

4.38.58-25

58'4I

1 5*68

17*27

i AurisrsB (3} .

4. 48.33-77

34/4.2

5 1 -68

17*26

ft Tauri

5. 1 8. 5-74

6-3o

23-8 1

I7*5i

a Leporis

5. 26. 56-44

56-46

i3*66

17-20

a Orionis

6.48. 7'io

7'3g

24*60

17*21

a, Geminorum (4) .

7. 26. ig'Sg

20-22

37*42

17*20

a Canis Minoris

7.32. 28-02

28-07

45*46

17*38

ft Geminorum. .

7. 37. 22'22

22'5l

3q*qo

I7'3q

yl Leonis

IO. 12. 46*54

46-52

3*g3

17-41

« Hydrao (4) .

IO. IQ. 44-48

44- iq

172

17*53

f Leonis

IO. 25. 55-34

55-23

12*84

17*61

Nov. 22

B

W

i Piscium

23. 33. 12-92

1 3 '04

3o*85

17*81

8 Sculptoris (4) . ,

23. 42. 7-02

6-90

24*85

I7*g5

a Piscium

23. 52. 35*i5

35-28

53*25

'7'97

2 Ceti

23. 57. 2'12

2-09

20*04

I7*g5

a Andromedse

O. I. 37'IQ,

37-50

55*3o

+ 17*80

November 21. A very high wind rendered the clock generally inaudible.
November 21-22. The transit micrometer was set at 19" 740 for all clock stars.
Adopted Azimuth, November 22, —6"* 06.

EB 2

310

TRANSIT OP VENUS, 1874. EGYPT.

1874.

Observer.

1'osition of
Micrometer Head.

Star and (Number of
Wires when less than Five).

Mean observed
Clock Time
of Transit over
the Center Wire.

Seconds
of True
Transit
over the
Meridian.

Star's
Assumed
Apparent
K.A.

Clock
apparently
Slow.

Nov. 2 2

B

W

v Pesrasi . .

h m s
O. 7. 2Q'6l

2q-78

S

47'7O

s
4- I7'q2

i Ceti

O. l3. 4.5'4-Q

4.5*4.0

3'4O

I 7'qi

44 Piscinm

o. 18. 4i'52

4.1'Ql

5o"54.

I7'q3

1 2 Ceti

o. 23. 2i'38

21*43

3a'4.5

18-02

( Andromedse

o. 3i. 38-62

38'Q4

56*Q2

I7'q8

0 Ceti

o. 37. i'i3

I -08

IQ'O2

i7'q4

a Arietis

i. 5q. 4.o'65

5o"2O

7-87

' f*

17-67

B

67 Ceti

2. 10. 27-88

27'6q

4o'3o

17-61

f2 Ceti

2.21. i3'3q

l3'34

3ri2

17-78

e Tauri

4. 21. l'q8

roq

iq'48

I7'8q

a. Tauri (A.) .

4. 28. 27'85

27-45

45'34

I7'8q

i Auriga;. .

4. 48. 34'3q

34'o6

51-70

17-64

e Orionis

5. 29. 35'2g

34-80

52-66

17-86

6 Cancri (4) .

7. 55. 32'7q

32-43

5o-3o

17-87

1 5 Argus

8. 1.55-86

55'2i

1 3- 1 q

I7'q8

8 Cancri

8. q. 26-48

26-04

43"q6

I7"Q2

Dec. i

B

W

€ Piscium

o. 56. 4-78

4'55

27-35

22 80

@ Andromeda}

. 2. 21*07

21-07

44-04

22-97

6 Ceti

. 17. 24-46

24' I I

4.6'7O

22'5q

E

y Piscium

. 35. 32'go

32-86

55'7i

22-85

o Piscium

. 38. 2o-o3

25"o3

47*74

22'7I

|S Arietis

. 47. 2I'3o

2 I"4I

44*25

22-84

Dec. 4

B

F.

i Ceti

o. 1 3. 3g'3i

38-73

3'2Q

24*56

44 Piscium

o. 1 8. 35-i6

34'72

5a*45

24*73

1 2 Ceti

o. 23. i5"i4

1 4-63

3g-36

24*73

f Andromeda?

o. 3i.32'o6

3ro3

56-82

24*80

8 Ceti (4) . .

o. 36. 54-73

5±*o5

18-92

24-87

8 Piscium

o. 41. 47'33

46*04.

i r65

H'71

20 Ceti

o. 46. I2'86

12*37

37'o5

24*68

p Andromeda?

O. 4q. 24"o6

24/o6

48"7q

24'?3

e Piscium

o. 56. 2-96

2*O7

27-33

24-76

Polaris, 1 8r • 1 90

. 8.21-60

44" 6 1

5-21

20-60

W

Polaris, 1 8 ' ' 1 90

. 1 6. 14-00

36-o6

5-21

2g-i5

» Piscium

. 34.31-26

3o'73

55-70

24"q7

o Piscium

.38.23-28

22-78

47-73

H'q5

|S Arietis

. 47. 19-62

IQ'24

44-24

25"OO

f Tauri

4. 20. 54-90

54-6q

iq'64

24"q5

a. Tauri

4. 28. 20-84

2O'OQ

4,5*40

24"qo

r Tauri

4. 34. 20-38

2O*22

45' 1 6

24"Q4.

/* Eridani

4. 38. 5 1 -40

5o*o3

i5-85

H'q2

E

< Aurigae

4. 48. 27-12

26-02

5l'q2

25'OO

e Leporis

4. 5q. 46-98

* »«

4O"2O

i ri3

24'q3

(3 Orion-is

5. 8. 8-40

7-78

32'56

+ 24-78

The transit micrometer was set at 19'- 740 for all clock stars, November 22 ; and at \<f '690, December i and 4.
Adopted Azimuth Error, December i, —7" -43.

MERIDIONAL TRANSITS, MOKATTAM.

311

1874.

Observer.

Position of
Micrometer Head.

Star and (Number of
Wires when less than Five).

Mean observed
Clock Time
of Transit over
the Center Wire.

Seconds
of True
Transit
over the
Meridian.

Star's
Assumed
Apparent
K.A.

Clock
apparently
Slow.

Dec. 5

a

\V

2 Ceti

h m s

23. 56. 55-32

8
54-41

s
iq-go

s
+ 26-49

a Andromeda

O. I. 2q'.>2

2Q'27

55"i5

20-88

y Pesrasi ,

O. 6. 22'22

2T75

47-08

25-83

1 2 Ceti

O. 23. 1 4.' 4.4.

i3'7O

3g-35

25-65

e Androinedas (4)

o. 3i. 3i'i2

3o-qo

56-8i

25'qi

]3 Ceti

o. 36. 54-28

53-34

18-01

20-57

E

20 Ceti

O. 4O. 12' 1 4

1 1"55

37 -o5

25'5o

ft. AndromediE

o. 40. 23' i o

23'2I

48-78

25-57

P AndromediB

. 2. l8'2O

1 8 -33

44-01

25-68

Polaris, 1 8r ' i go

. 8. 0-60

35-5 1

4-73

29-22

W

Polaris, 1 8r • 1 90

. 16. 8*40

42-72

4-73

22'OI

i\ Piscium

. 24. 22'52

22'l5

47-75

25'6o

> Piscium

. 34. 3o-6o

3o-o8

55-70

25-62

o Piscium

. 38. 22'52

22"o6

47-72

25-66

E

7 Tauri

4. 1 2. i6'o8

1 5-65

41-41

25-76

e Tauri

4. 2O. 54'34

53-96

19-66

26-70

a. Tauri

4. 28. 20-28

19-86

45-5i

25'65

•c Tauri

4. 34. iq'q3

10-62

45-17

25-55

W

pi Eridani

4. 38. 5o-qq

40-07

i5-86

25-89

i AurigEe

4.48. 26-78

26-21

5i-g3

26-72

e Leporis

4. 5q. 46-34

45-12

1 1*14

26-02

Dec. 7

B

w

i Piscium

23. 33. 4-20

3-8o

30-71

26-91

i Ceti

O. 12. 37'O2

36-42

3-26

26-84

12 Ceti

o. 23. 12-88

12-36

39-33

26-97

i Andromedas

o. 3i. 20-87

29-80

56-79

26-99

E

8 Piscium

o. 41. 45-10

44'6g

u-63

26-94

20 Ceti

f -
o. 46. lo'oo

9-97

37-o3

27-06

p. Andromedte

o. 4q. 21-88

21-92

48-76

26-84

e Piscium

o. 56. o-65

0-24

27-31

27-17

o Tauri

3. 17. 38'qo

38-67

5-78

27-1 1

/"Tauri

3. 23. 32-o6

3i-82

88-87

27-06

€ Eridani

3. 26. 36-43

35-Sg

3-17

27-28

Dec. 8

B

W

K Piscium

23. 20. 3-71

3-3 1

30-84

27-53

i Piscium

23. 33. 3-5o

3-14

30-70

27-66

2 Ceti

23. 56. 52*q6

52-34

19-87

27-53

a Andromeda;

o. i. 27-56

27-47

55-12

27-66

y Pegasi .

o. 6. 20-16

19-90

47-55

27-66

•

i Ceti

o. 12. 36-24

3575

3-25

27-60

44. Piscium. .

o. 18.32-27

3rg2

69-41

27-49

1 2 Ceti

o. 23. 12-36

1 1-94

3g-32

27-38

j3 Ceti (2)

o.36. 52-26

5 1 -66

18-88

27-22

8 Piscium ( i )

o. 41. 44-65

44'36

1 1-62

27-26

20 Ceti (i)

0. 46. Q"04

9-54

37-02

27-48

a. Orionis

5. 47. 57-54

57-21

24'94

+ 27-73

Adopted Azimuth Error, December 7, —12" -41.

December 5 to 8. The transit micrometer was set at it? -690 for all clock stars.

312

TRANSIT OF VENUS, 1874. EGYPT.

1874.

Observer.

Position of
Micrometer Head. 1

Star and (Number of
Wires when less than Five).

Mean observed
Clock Time
of Transit over
the Center Wire.

Seconds
of True
Transit
over the

Meridian.

Star's
Assumed
Apparent
R.A.

Clock
apparently
Slow.

Dec. 8

B

E

8 Ursse Min. S.P., igr-O23 (3)
Cephei 5i, i5r° 190 (2)

h m s
6. 12. 47'5o

6.35. 5-5o

s
54-10
8-68

s
20'gi

36- i8

e
+ 26-8I
27-60

8 Leonis (2)

ii. 6. 5g-68

59-54

27-06

27-62

8 Crateris (3)

II. 12. 37'5q

37-04

4-77

27-73

f Leonis (3)

I I. 21. 2-25

I -9 1

29-81

27-90

Dec. 9

B

E

1 2 Ceti

o. 23. 1 1-47

10-96

3g-3i

28-35

f Andromedse

o. 3i. 28-5o

28-49

56-77

28-28

ft Ceti

o. 36. 5 1 '36

5o-65

18-87

28-22

20 Ceti

o. 46. q'35

8-87

37-01

28-14

/ji Andromeda;

o. 40. 2o'38

20-54

48-73

28-19

E

Polaris, 1 8" 940 (2)

. 10. 5'oo

35-48

2'3o

26-82

W

Polaris, 18'- 190

. 1 6. 2-80

32-94

2-3o

29-36

tj Piscium (3). .

. 24. 20-07

19-76

47-72

27-97

v Piscium

. 3^.. 28'IO

27-66

55-67

28-01

o Piscium (4)

. 38. 20-07

19-67

47-70

28-03

ft Arietis

. 47. 1 6'38

i6-i3

44-22

28-09

v Ceti

2. 28. 61-44

5 1 -oo

19-19

28'iq

y2 Ceti

2.36. 22-06

2i-5g

49-83

28-24

Dec. 10

B

•W

a Columba;

5. 34. 40-26

3g-2i

8-70

29-49

a Orionis

5. 47. 56'48

55'q7

24-07

2q'OO

i Geminorum

5. 56. 3-oo

2-71

32-ci

2g-3o

v Orionis

5. 5q. 57*q4

57-54

26-78

29-24

E

/* Geminorum

6. 14. 55-6o

55-49

24-59

29-10

ft Canis Minoris (4)

7. 19.53-88

53-68

22-83

29- 1 5

«2 Geminorum

7. 26. 8-60

8-79

38-o3

29-24

a Canis Minoris

7. 32. 17-10

1 6-85

45-97

29-12

ft Geminorum ....

7. 37. n-36

1 1-46

4O*5o

29-04

Dec. 14

B

W

7 Pegasi . ,

o. 6. i6'i i

i5'q3

47-49

3 r56

1 2 Ceti . .

o. 23. 8-07

7-56

39-26

31-70

e Andromeda;

o. 3i. 24-80

24-92

66-70

3178

E

ft Ceti

o. 36. 47*80

46-96

18-81

3r85

8 Piscium

o. 41. 40-18

39-79

11-67

31-78

20 Ceti

o. 46. 5'6o

5-o5

36-g6

3i-gi

f Piscium

o. 55. 55-77

55-38

27-26

31-87

Polaris, i8r'44o (4) .

i. 8.26-75

24-16

58-32

34-17

W

Polaris, 1 8r ' i qo

i. 1 5. 00-40

28-58

58-32

2974

v Piscium

i. 34. 24-06

23'6o

55-64

32-04

a Arietis

I. 5q. 35-78

35-63

7-81

32-i8

f ! Ceti

2. 5.61-07

5o-66

2276

32-10

67 Ceti

2. 10. l3'82

13-17

45-26

32-o8

« Tauri ....

4.. 28. l3'74

i3-6o

46-69

3i"qq

T Tauri

4. 34. l3'22

l3'22

46-26

32-04

M Eridani (4"). .

4. 38. 44*37

43-88

16-94

+ 32-o6

December 9 to 14. The transit micrometer was set at i^"6y> for all clock stare.

MERIDIONAL TRANSITS, MOKATTAM.

313

i874.

a t-
.22

Star and (Number of
Wires when less than Five).

Mean observed

Clock Time
of Transit over
the Center Wire.

Seconds
of True
Transit
over the
Meridian.

Star's
Assumed
Apparent

R.A.

Clock

apparently

Slow.

Dec. 14

W

E

i Aurigje. . .
/? Orionis . .

j3 Tauri

8 Orionis . .
a. Leporis . .
€ Orionis . .
a ColumbEe.
K Orionis .

4.48.1970
5. 8. 1-16
5. 17. 5rg8
5. 25. 6-22
5. 26. 42-65
5. 29. 21-43
5. 34. 37-36
5.41. 1 8-g3

Dec. 1 5

w

, Ceti

44 Piscium

1 2 Ccti

( Andromedae. . .

ft Ceti

8 Piscium

20 Ceti

/x Androinedae . .

e Piscium

Polaris, 2ir'igo
Polaris, 2 1 ' • i go

i) Piseium

v Piscium

o Piscium

j9 Arietis

a Arietis

f ! Ceti

67 Ceti

12.

18.

23.

3i.
36.
41.

46.

49-
55.

7-
1 5.
24.

34.
38.

47-

59.

5.

10.

3i-3i

27-27
7-27
24-04
47-17
3g-68
5-io
16-04
55-12
49-80
40-00
i5-26
23-38
15-36
11-68
35-3o
5o-5i
1 3-33

19-92
0-6 1

52'og

5-8 1

41-92

21-00

36'2g
18-34

3o'6o
26-76
6-66
24-04
46-26
3g-22

4'47
16-18
54-66

27-07

22'01
I 5-04
22-gS
I 5-04
11-48
35-14

5o-og
12-67

52-04
32-67
24-23
38-02
14-00
53-oi
8-70
5o-5i

3-i8
5g-35
3g-25
56-6g
1 8-80
ji-56
36-95
48-66
27-25
57-46
57-46
47-68
55"63
47-66
44-18

7-80
22-75
45-24

+ 32-12

32-o6
32-14

32-21

32-o8
32*01
32-46
32-17

32-58
32-5g
32-5g
32-65
32-54
32-34
32-48
32-48
32-5g
3o-3g
35-45
32-64
32-65
32-62
32-70
32-66
32-66
+32-57

December 15. The transit micrometer was set at 19^690 for all clock stars.

314

TRANSIT OF VENUS, 1874. EGYPT.

TABLE XVII. — ERRORS and RATES of the TRANSIT-CLOCK at MOKATTAM.

Approximate
Local Mean Solar
Time.

Observer.

Approximate
Sidereal Time.

Adopted
Clock Slow.

Clock's Loss
in preceding
J4h. Sidereal.

Adopted
Losing Rate.

1874.

d h

Nov. 4. 10

13

b m

o. 37

8

+ 2rg3

8
I 0'08

8
+ O-Og

5. ii

I!

2. l6

22'04

O'lO

o-i5

i3. 9

B

0.47

i3'7i

0-08

0-19

14. 1 1

B

2. 25

14-03

o-3o

0*29

i5. 1 1

B

2. 2O

i4'3i

0-28

0-29

18. 8

B

23.52

15-27

o-33

0-46

>9- 9

B

0.32

15-78

o-5o

o-65

20. 10

B

1.32

16-62

0-8 1

0-64

21. 12

B

4. I

17-14

0-47

0-62

22. I I

B

2.48

17-87

0-77

0-78

24. II

B

2. 45

19-46

0-80

0-68

27- 9

B

1.43

20-97

O'OI

o-56

28. 10

B

2. 0

21-55

0-57

o-5o

3o. 12

B

4. 3o

2 2-3 1

o-36

0-48

Dec. i . 9

B

1.23

22-79

o-55

o-58

2. 9

B

1.43

23-42

0-62

o-6g

3. 9

B

1.35

24-17

0-75

0-71

4. 10

B

2.3o

24-87

0-67

0-75

5. 9

B

2.19

25-69

o-83

0-78

7- 8

B

i. 3

27-00

0-67

O'Sg

8. 9

B

2. 2

27-57

o-55

o-58

9- 8

B

1.17

28-16

0-61

0-73

10. 1 3

B

6.32

zg'ig

o-85

0-70

u. 7

B

0. 25

29-60

o-55

0-64

12. 9

B

2. 5

30-37

0-72

o-75

14. 10

B

3. 18

32-01

o'8o

0-69

i5. 8

B

i. 6

32'5g

0-64

0-73

16. 6

B

23.58

33-37

0-82

°79

21. 7

B

o. 46

+ 36-5o

+ 0-62

+ 0-62

ALTAZIMUTH CLOCK COMPARISONS, MOKATTAM.

315

0 _.;

A |j

^ "g, *2

J

J^O'S 0.

• b b b

b

1 <

1 1 1

+

1C ^O W \O

1.* oH ^

B fi fe • fl

w <^0 r^. 10 b^ — "d

oo p
b -

M N C4 M

r< N

4 ^ « w

B - - -: -

II II

op p P p p

O O

"= §

10 t^ ^- in ^ vb o

Vn b

« g * *

rO Ci w in w

m N

a 'N $> eL
S S — g

a vo 4- « \o cy» vo"

OO TJ-

w •*

3 °

J3 tO <O N N N ^

C4 4*

•s

o in op o m
« b b b b b -

in p

O^ O*>

M H CO « —

- •*•

'1 J

53 5 O

3 o" t^ o in -*- o>

•4- m to •*• m

m •>*•

11 3

ja oo w r^ ** in in

10 «

0

- 0

V g

11

Js 1

op P P p in
• ih r< in '- bo

in p
r->. o

G o

B f

"35

S r-» O ^- — vo to

•4- \n - •*- •*•

o 4-
in to

g

ja oo cj t^ ^ in in

in -

s

.

p p P P P P

P P

o o

« oo b b b in N

m to m —

O CTi

a) > a.
•i'S I

0 N VO NO — 6

6 4-

ti

H gO

03 to «<3 c< n rJ iA.

« 4-

CV 9 d

^ C3

•*• s m I r^ «

M

00 .,

.

4-

t*^ t*

Q

OO ^j

1

o

8 8

316

TRANSIT OP VENUS, 1874. EGYPT.

TABLE XIX. — ZENITH DISTANCES of STARS observed near the MERIDIAN "with, the

1874.

ij

E
O

Star.

Time by the
Altazimuth
Clock.

B

S

bO

(3 .

IS

1-1

Circle-Beading
corrected for
Runs of
Micrometers.

Level
Indication
additive.

Barometer
and
External
Thermo-
meter.

Refraction.

h m s

o / //

//

tt

Nov. 4

B
B

Polaris

i. 6.53-0
i. 1 5. 43*0

E

L

211.52. 67

32g. 3. 10*6

87*7
78-2

2gin*46
6i°-o

9°'9

QO'Q

B

a Persei . . . ,

3. 7. 6-0

L

289. 55. 36*9

/ "

70-9

y j
»97

5

B
B

,, ....
Polaris

3. 1 6. 3-o
i. 1 5. 57*0

R
L

25i. 4. 42-5
329. 3. 8-5

8g-5
77*3

2gin*5o

I 9'6
QO'2

B

I. 24.. Q'O

E

211.52. 5*5

II

87-6

65°-7

•~J^r

QO'2

27

B

y Fiscium . . .

T J

23. ii. 1 3*o

E

243. 2. 34*4

V f V

63-i

* /

29^-44

;7

287

B
B

»> • • •
1 2 Ceti

23. 19. 7*0
o. 20. 56'o

L
L

297. 57. 36'o
3o5. 8. 87

8g-5
66-6

64°*o

28-9

38-2

B

O. 27. 57'O

E

235.46. ro

07-8

38*3

B

j3 Ceti

ti
o. 35. 5i'o

E

T

221. 46. 6*2

J 1

80-7

62-8

B

o. 4.1. 36°o

L

3iq. q. 44'8

"y 1

66-5

62-0

B

t Piscium . . .

0.52. 1*0

L

y j TT

2g3. 17. n*3

74-1

y
21-7

B
B

»» ...
Polaris

i. o. 1 5*o
i. 8. 14*0

E
L

247. 37. 47-8
32g. 2.53'5

90-8

QI'2

21-7

QO'3

B

i. 1 6. 14*0

E

211. 52. g*O

3
75'2

-~fv
QO"3

B

a Persei ....

3. 11.42*0

L

289. 5o. 55' i

/

89-5

J

19-5

B

»

3. 1 8. 32*o

E

25i. 4. 47

74-6

19-5

B

a Aurigas . . .

5. 4. 55*o

E

264. 36. 56-8

80*3

i57

B

), ...

5. i3. 1 8-0

L

286. 20. 22*7

83-1

i57

B

8 Orionis . . .

5. 21. ro

E

240. 1.44-9

84*6

32-5

B

)> ...

5. 28. 23*o

L

3oo. 52. 44-7

82-5

32-5

B

« Orionis . . .

5. 42. 59*0

L

2g3. 7.39*9

86*7

29in-44

23-io

B

,j ...

5. 5o. 7*0

E

247. 48. 45-5

85*5

64°*o

23*10

OBSERVATIONS FOR LATITUDE, MOKATTAM.

317

VERTICAL CIRCLE of the ALTAZIMUTH at MOKATTAM, and INFERRED CO-LATITUDE.

Zenith Point,
including Zero of Level.

Concluded
Zenith Distance.

Reduction
to the
Meridian.

Star
N. or S.
of Zenith.

Tabular
Apparent N.P.D.
of Star.

Inferred
Co-latitude.

Observed.

Adopted.

270°. 28'

O / II

n

O 1 II

O 1 II

1 "
} 62-9

62-5

58. 36. 5g-o
58. 36. 57-2

27
O'l

N.

I. 21. 2O-g

5g. 58. 17-2
1 8-0

j 62-1

62-5

19.28. 5*o
19. 23. io-i

2g6'6
0-8

N.

40. 35. 4- 1

> »

12-5

1 3-3

58. 36. 54-5

0-6

N.

I. 21. 20-4

H-3

> 6i-5

6r5

58.36.58-6

4-2

»

i4-3

27. 25. 5i-6

3-o

S.

87. 24. 4-8

16-2

> 60-4

60-4

27. 3o. 34-4

285-4

,,

16-2

i

34.41. r6

16-8

S.

g4. 38. 56-i

12-3

| 5o-8

5rg

34. 41. 5 1 -4

64-3

,,

9-0

,

48.42. 1 8-8

2-6

S.

108. 40. 2g'4

l3'2

\ 5rg

5rg

48. 43. 2-3

46-0

,,

i3-i

1

22. 49. 55-2

7-3

S.

82.47.58-3

12-4

> 52"!

5rg

22. 49. 55-o

7-5

,,

10-8

,

58.37- 3-i

i-5

N.

I. 21. l3'I

14-8

f ^4'°

5rg

58. 36. 58-o

0-6

> >

io-5

ig. 23. 52-2

38-o

N.

40.34. 5g-2

1 1-4

52-g

5rg

19. 23. 52-i

3g-8

,,

H-5

1

1 5. 5o. 5o"5

21-2

N.

44- 7.48-I

17-4

} 49-5

5i-g

1 5. 53. g-6

1 65- 1

,,

12-6

3o. 26. I4'g

61-4

S.

go. 23. 26-6

i3-i

[ 53-o

5rg

3o. 25. 47-8

32-1

,,

10-9

22.40.37-8

n 3-5

S.

82.36.56-i

11-8

1 5ri

5rg

22. 38. 54-0

18-1

"

5g. 58. 20-2

ss 2

TKANSIT OF VENUS, 1874.

PART II.
EXPEDITION TO EGYPT

(continued).

Section 2.
DETERMINATION

OF THE

LONGITUDE OF ALEXANDRIA

BY LOCAL TRANSITS AND EXCHANGE OF TELEGRAPH
SIGNALS WITH MOKATTAM STATION,

FROM THE

OBSERVATIONS OP SAMUEL HUNTEK, ESQ.

CONTENTS.

PAGE

Extract from a Letter of Proceedings from Mr. S. Hunter to the Astronomer

.Royal - . - 321
Description of Instruments - - - - - -321

Description of Chronometers - - - 321

Instrumental Constants - 322

Adopted Error of the Observing Chronometer - - 322

Position of the Transit Instrument at Alexandria - - 323

Transits of Stars observed at Alexandria - - 323

Errors and Bate of the Observing Chronometer - - 326

Comparisons of the Chronometers • ... 327
Errors and Eate of the Signalling Chronometer on Alexandria Mean Solar

Time - 327

Errors and Rate of the Signalling Chronometer on Mokattam Mean Solar Time 328

Difference of Longitude from each day's signals - - 328

Corrections for Personal Equation, &c. - - 329
Final Longitude of Alexandria (Hotel de 1'Europe) - - - -330

321

LONGITUDE OF ALEXANDRIA.

EXTRACT from a LETTER from MR. S. HUNTER to the ASTRONOMER ROYAL.

My work in Egypt in connection with the Transit of Venus may be divided
into three periods : —

First, at Cairo, assisting" Captain Browne in transporting material, &c., to
Mokattam, erecting huts, &c., from the 15th to 26th October 1874.

Second, at Alexandria in connection with the determination of longitude,
October 27 to November 25.

Third, at Suez (where I observed the Transit), from November 26 to
December 24.

The instruments with which I was furnished were the property of the
Royal Astronomical Society, and consisted of —

(1.) An equatorial of 4'6 inches aperture, by T. Cooke and Sons, of York,
driven by clockwork, and furnished with Solar eye-piece and divided eye-
glass double-image micrometer. This instrument on landing in Egypt was
stored in Suez until my return there.

(2.) A Transit instrument (Sheepshanks No. 1) with aperture of
2'6 inches, mounted on a portable metal stand, which was fastened by
two screws to a stone slab, resting on a brick pier. The wire frame carried
nine fixed vertical wires and two horizontal ones ; there were also two
movable vertical wires connected with the micrometer screw. Power used
= 77 diameters.

I had the box, 2-day chronometers Loseby 102, regulated to sidereal time,
beating half seconds, and the solar chronometer Hewitt 890, also beating half
seconds.

The work in Cairo requires no further observation. At Alexandria the
first duty was the selection of a site as convenient to the Telegraph Office as
possible. Having examined several places, I decided on using the roof of
the Hotel de FEurope, as it appeared most suitable. It is distant five minutes
walk from the Telegraph Office. The walls of the Hotel de FEurope are
2 feet 3 inches thick, and just over the intersection of two partition walls of
the same thickness the transit pier was erected.

On October 30 I commenced observing with the transit instrument in
order to determine the wire intervals, value of micrometer screw, and pivot

322 TRANSIT OP VENUS, 1874. EGYPT.

errors of the transit, as this instrument came from Mr. Simms' factory only
just in time to be packed up before leaving Greenwich ; consequently all
instrumental corrections had to be determined before a single observation
could be reduced. I soon discovered that the micrometer-screw was decidedly
drunken, and was compelled to abandon its use. This entailed very serious
loss of time every night, and compelled me to trust to observing the pole star
in both positions of the instrument over the fixed wires for collimation, as
well as for azimuth errors.

Having no covering for the instrument, I carried it into my room and put
it in its box each night.

On November 24 I packed the instruments and returned to Cairo.

S. HUNTER.
(Continued on page 333.)

MERIDIONAL OBSERVATIONS at ALEXANDRIA.

Mr. Hunter's observations for local time were continuous from 1874,
October 30 to November 23 ; but have special value only on those nights
when signals were exchanged with Mokattam.

The Level Error was determined by a striding spirit-level graduated from
the center outwards in the old way ; 40 divisions were equivalent to one
minute of arc.

After his return to England Mr. Hunter carefully determined the Pivot
Correction to be 0"'88, positive with the Micrometer Head East.

The Equatorial Intervals of the nine vertical wires were determined from
numerous transits of circumpolar stars over the entire set. The correction
to reduce the mean of the wires to the center wire was 1"'58, positive with
Micrometer "West.

The Collimation Error of the center wire was determined by observations
of polar stars with reversed positions of the Transit axis.

The Azimuth Error has been obtained, and the reductions effected in the
same manner as at other stations.

The Diurnal Aberration is taken account of as a correction to the Longitude.

In adopting the Error of the observing Chronometer (Loseby 102) equal
weight has been given to the observations in each of the reversed positions
of the transit instrument, irrespective of the number of stars observed.

It was Mr. Hunter's custom to compare the two chronometers (by coinci-

LONGITUDE OF ALEXANDRIA.

323

dence of beats) on concluding the star observations. Thus each chronometer
was available for carrying on time. The Errors and Rates of Hewitt 890
thus obtained are given separately, page 327. The only occasion, however,
when they can be employed with sensible advantage is on November 22, when
there were no star observations.

The position of the Hotel de 1'Europe is taken with sufficient accuracy from
the Admiralty Chart, viz. : —

2,940 British yards East and 400 yards North of the Light-House on

EUNOSTES POINT ;

620 yards East and 1,940 yards South of the ancient PHAROS ;
the approximate Latitude being 31°. 11'. 55". N.

MERIDIONAL TRANSITS observed at ALEXANDRIA by MR. S. HUNTER.

1874, November 14.

Position of Micro-
meter Head.

Star.

Mean observed
Time by Losehy 102
of Transit over the
Center Wire.

Seconds of
True Transit
over the
Meridian.

Star's assumed
Apparent
H.A.

Loseby 102
apparently
Blow..

E
E

w

W

20 Ceti

h m B •
O. 44. 49*62
0.48. 3 '09
I. 12. 48-3i
I. l3.34'24
2. 4-36-77

2. g.58'52
2. 19.44-95

2. 27. 32'8g

2. 3i. i8'36
2.35. 3'53
2. 42. 5o'02
2. 5o. 18-68
3. 2.43-50

3

5i-68
3-32
3i-38
29-72
37-19
Sg'Sg
45-37
33-49

i9'"7
4-21
5o- 12
18-52
43-42

3
37-2I
48-98

i5-g3
i5"g3
22-80
45-29
3i • 10
19-16
4-96
49-78
35-79
4-26
29-25

3

+ io5-53
io5'66
104-55

1 06 - 2 I

io5'6i
105-70
105-73
105-67
105-79
105-57
105-67
105-74
+ io5'83

/* Andromedie

Polaris (5)

Polaris (4.) . ,

£i Ccti

67 Ceti

f*Ceti

v Ceti

8 Ceti

72 Ceti

<r Arietis

( Arietis

8 Arietis

Level Error.

h m "
I . o Sid. (E.) —0-21 Colliraation Error by Polaris, 7'' • 6 ( + E., — W) (adopted,

1.25 „ (W.) - 2-42 7"'9)-
2.55 „ (W.) — 1-74 Azimuth Error by /Wan'sand 67 Ceti, +4i"'7 (adopted).

T T

324

TRANSIT OF VENUS, 1874. EGYPT.

MERIDIONAL TRANSITS observed at ALEXANDRIA by MR. S. HUNTER.

1874, November 15.

Position of Micro-
meter Head.

Star.

Mean observed
Time by Loseby 102
of Transit over the
Center Wire.

Seconds of
True Transit
over the
Meridian.

Star's assumed
Apparent
K.A.

Loseby 102
apparently
Slow.

W

w

E
W

a. Gruis

h m s
21. 58. 32 '29

22. 8.28'l3
22. l3. 25'6o
22. 22. l5'2I

22.27. 9'8o
22.33. 28*04
22.42. i3'36
22.48.57-27
22. 56. 46-81
6. 10. 9 '37
6. 40. 1 9 • o3
6. 40. 41 • 23

s

35-45

29-32
26-59
16 -55
10-75
28-54
i3' 17
59'39
47-06
41-32
42-76
42-76

8
20-26

13-44

II-22
1 -21

55-27

12 -g5
57-56
44-10
3i-5i
26-98
28-36
28-36

8
+IO4-8J

IO4-I2
I04-63

i 04 • 66
104-52
104-41
104-39
104-71
i 04 - 45
io5"66
i o5 - 60
+ io5'6o

6 Aquarii

•v Anuarii .

<r Aquarii

)j Aquarii

£ Peeasi .

n* Pegasi

8 Ursae Minoris S.P. . . .
Cephei 5i (5)

Cephei 5i (3)

Level Error.

h m "

20.48 Sid. (W.) + 1-67 Collimation Error by Cephei 5i, f'g (+ E., — W.)
(adopted).

22.64 » (W0 — °'8'
Collimation Error, Nov. 16, Polaris, 8"' I ( „ „ )
6. 8 „ (E.) + o-o5
Azimuth Error by 8 Ursae Minoris S.P. and Cephei 5i,
6.27 „ (E.) - 1-97 + 40" "5 (adopted).

6.34. (E.) — 0-88 November 16. Azimuth Error by Polaris and 67 Ceti,
+ 40'" 8.
6.49 „ (W.) - 1-29

LONGITUDE OF ALEXANDRIA.

325

MERIDIONAL TRANSITS observed at ALEXANDRIA by MR. S. HUNTER.

1874, November 21.

Position of Micro-
meter Head.

Star.

Mean observed
Time by Loseby 102
of Transit over the
Center Wire.

Seconds of
True Transit
over the
Meridian.

Star's assumed
Apparent
E.A.

Loseby 102
apparently
Slow.

W
E

t Peffasi .

h m s
22. 34. 28' 17
22. 43. l3'68

22. 5o. 57 -g3
o. 22. 55*69
o. 3i. 14*80
o.36. 34-61
o. 41. 28-41
i. 14.43-95
i. 1 3. 5o- 19
1.47. 0-43
2. 4. o-g5
2. 5.38-30

2. IO. O'2O
2. 2O. 46-59
2. 28.34-50

2. 32. 20*09
2.36. 4-98
2.43. 5 1 '66
3. 32. 35' 09
3.36.3o -89
3. 47-35-25
3.56.34-75
4. 5. i • 09

8

29-48
I4-38

0-61
66-62
14-01
36' ig
28-77
29-84
29 -83

''47
2-49
39-84
2-3g
48-i3
36-21

2i'94
6-78
52-gi
36-oo
33-35
45-83
35-78
3-37

I
12-88
57-48
44-01
39-46
56 -gi
ig-o3
11-73
12-68
12-68

44-27
45-58
22-81
45-3o

3l'I2

ig-i8

4-98
49-82
35-82
18-77
i6-23

29 '74
18-78
46-37

s

+ 43'4°
43*10
43-40
42-84
42-90
42-84
42 -g6
42-84
42-85
42-80
43 'og

42 '97
42-gi

42 '99
42-97
43*04
43-04
42-91
42-77
42-88
43-91
43-00
+ 43-00

u. Peeasi .

Fomalhaut

1 2 Ceti

f Andromedse

(3 Ceti

S Piscium

Polaris (5)

Polaris (4)

jS Arietis

64 Ceti

Ji Ceti

67 Ceti

£-' Ceti

v Ceti

S Ceti

y2 Ceti

T Ai'ietis

1 1 Tauri

8 Eridani

£ Ursa; Minoris

A1 Tauri

o1 Eridani

Level Error,
h m "

22.55 Sid. (W.) +I2'g5 Collimation Error, November 19, by Polaris, 8''-g4
23. o „ Level adjusted. (+ E., — W.).
0.26 „ (W.) — i '48 Collimation Error, November 21, by Polaris, 8" '20
0.54. „ (W.) - 6-61 (+ E., - W.) (adopted).
i. 5 „ (W.) — 6-3i Azimuth Error, November ig, by Polaris and 67 Get i,
i. 25 „ (E.) — 1-48 + 45"-oi.
2.40 „ (E.) — 2 '38 Azimuth Error, November 21, by ft Ceti and Polaris,
4. 5 „ (E.) + 1-46 + 42" -56 (adopted).
Azimuth Error, November 21, by 5 Ursie Minoris and
A1 Tauri, + 48" '55.

T T 2

326

TRANSIT OF VENUS, 1874. EGYPT.

MERIDIONAL TRANSITS observed at ALEXANDRIA by MR. S. HUNTER.

1874, November 23.

o

OS

a t.

0 4<

Star.

Mean observed
Time by Loseby 102
of Transit over the
Center Wire.

Seconds of
True Transit
over the
Meridian.

Star's assumed
Apparent
R.A.

Loseby 102
apparently
Slow.

11

S

h m s

8

s

s

E

5 Sculptoris

23. 41. 37 "5g

A.O ' 78

H" 72

, .5.Q.

a Piseium

23. 52. 8"oo

53-25

2 Ceti

23. 56 33 '66

36" 24

IQ ' Q3

a Andromedfe

O. I. I I "22

ii'73

55" 2Q

43-56

o. 6. 3'o5

4.' 21

A.1 ' 60

Polaris (3)

I. 1 3. 4Q'75

3o* IQ

1 1 '92

41 *73

W

Polaris ^4)

1. 14. 42 "67

26-88

I I 'Q2

4.5 ' O4.

67 Ceti

2. Q. O'Q4

i*53

j.5 ' 3o

£2 Ceti

2. 20. 47 "32

4.7 ' 2O

3 1 ' 1 2

v Ccti

2. 28. 35-45

35 '52

19- 18

+ 43-66

Level Error.

h m n"'(\\
23.29 Sid. (E.) — 3'5o Collimation Error by Polaris (§". ) ( + E., — W.)

2. 3 „ (W.) -10-07 (adopted, 8" '2).

Azimuth Error by Polaris und 67 Ceti, -f 40" g5 (adopted).

ERRORS and RATES of the SIDEREAL CHRONOMETER LOSEBY 102 from the
Observations at ALEXANDRIA. Observer, R. HUNTER.

Approximate Local
Mean Time.

Sidereal
Time.

Loseby 102 slow on
Alexandria
Sidereal Time.

Loss in the pre-
ceding 24 hours
Sidereal.

Adopted Losing
Rate.

1874.

h

h m

a

8

a

Nov. i3, 14

4- 7

-f io6'3o

. ,

, .

14, 10

1.41

+ io5'65

-0-72

— I'02

15, 7

22. 30

+ 104-52

- 1'32

— 0'37

16, 10

I. 21

+ I oo' 1 8

+ o-59

. .

t

19, 10

2. 22

+ 42-93

. .

. .

21, 9

1. 21

+ 43-02

+ 0-04

O'OO

23, 9

I. IO

+ 4372

+ o-35

+ o-35

•f Advanced one minute.

LONGITUDE OF ALEXANDRIA. 327

COMPARISONS of CHRONOMETERS at ALEXANDRIA (by coincidence of beats).

Day.

Loseby 102,
Sidereal.

Hewitt 890,
Solar.

Day.

Loseby 102,
Sidereal.

Hewitt 890,
Solar.

1874.

h m B

h m 8

1874.

h m s

h m a

Nov. 1 3

7. o. o-o

i5. 28. 6'o

Nov. 20

3. 43. 7-0

I 1 . 43. 6'5

7. 3. 4-0

i5.3i. g-5

3. 46. I2'o

1 1. 46. i ro

7. 6. 8-0

1 5. 34. 1 3*o

3. 52. 16-0

ii. 52. 14-0

7. 9. i6'o

i5. 37. 2O'5

7. 12. i6-o

1 5. 40. 2O'O

21

5. 20. 47-0

i3. 16. 32-o

5. 26. 49-0

l3. 22. 35'O

•4

4. 23. 43-0

12.48. 17-5

5. 29. 5i-o

1 3. 25.36-5

4. 26. 46-0

12. 5l. 20'0

12.37. 46-0

2O. 32. 2I'O

4. 36. 2-0

I. 0.34-5

12. 43. 49*0

20. 38. 23-o

4. 3g. o-o

i3. 3. 32-o

12. 24. 14-0

20. 47. 2g'5

22

o. i5. 23-o

8. 8. 3-5

12. 27. ig'o

20. 5o. 34-0

o. 18. 28-0

8. ii. 8-0

8.43. 1 5-o

i5. 34. 42-0

i5

(a)23. 1 8. 42-0

7. 40. i o-5

8. 46. 1 3-o

1 5. 37.39-5

23. 21. 47-0

7. 43. 14-0

8. 4g. 17-0

1 5. 40. 43-0

g. 34. oo'o

17. 04. 36"o

g. 37. 54-0

(b) 17.07.40-5

23

g. 21. 5o-o

17. g. 4-0

g. 24. 53'o

(g) 17. 7. 6-5

16

(c) 2.21. i'o

(d) n.57.58-5

2. 44. 4-0

(c) 1 1. 5i. ro

'7

(/) 2. 56. 48-0

10. 10. 55*5

2. 2.58'Q

10. 1 6. 4-5

b m B

(a , probably, 23. 18.43-0

18

2. 2g. 42-0

10. 3g. 46-5

(b , „ 17.57.39-5

2. 32. 44-0

10. 42. 48-0

(c , „ 2.41. ro

(d , „ 10. 57. 58-5

'9

2.58. 16-0

II. 2. ig-5

(e), „ ii. i. ro

3. i. 1 8'o

II. 5.2PO

(/), „ i. 56. 48-0

3. 4.22-0

11. 8.24-5

(g), „ 17. 12. 6-5

ERRORS and RATES of the MEAN SOLAR CHRONOMETER HEWITT 890 from the
COMPARISONS with LOSEBY 102, made near the Epochs of Observations of Stars.

Day.

Local Mean Time.

Hewitt 890
Slow on
Alexandria

Loss in the
preceding
24 hours

Adopted Losing
Rate.

Mean Time.

Solar.

1874.

h m

8

e

8

Nov. 1 3

i5. 3o

+ io3-53

. .

. .

An independent

H

12.58

+ io3-g2

+ 0-43

+ 0-24

rate of Hewitt 8go

IS

7.42

+ io3'g5

+ 0-04

+ 0'74

is obtained by its

16

to.58

+ io5-6of

+ I-44

comparisons by

'9

ii. 8

+ io6-g5

. .

telegraph with

21

i3. 26

+ 108-28

•f 0-64

4 o-gi

the Transit Clock

23

g. o

+ 1 1 0-43 J

+ ri8

+ 1-18

at Mokattam (see

next page).

t Possibly some error ; the comparisons are difficult to understand.

J The Error, November 23, is obtained by combining comparisons made 17 hours before and 8 hours after the
observations for local time.

328

TRANSIT OF VENUS, 1874. EGYPT.

ERRORS and RATES of the SOLAR CHRONOMETER HEWITT 890 on MOKATTAM MEAN
SOLAR TIME from the exchange of Signals between MOKATTAM and ALEXANDRIA.

(Extracted from the Section Longitude of Mokattam, page 278.)

i874-

Time by
Hewitt 890.

Hewitt 890
Slow on
Mokattam

Adopted
Hourly

Mean Solar Time.

Losing Rate.

h m

m a

8

Nov. 14

14. 6

+ 7. i6-3g

_

i5

19.58
g.33

1 6. i

+ 7. 1 6-58
+ 7. 17-02
+ 7. I7-33

+ '032

+ -048

21

14. 14

+ 7. 20-88

' -.' -

19-47

+ 7.21-07

22

9. 2
14.39

+ 7-2174
+ 7. 22-09

+ -062

DIFFERENCE of LONGITUDE between MOKATTAM and ALEXANDRIA
(HOTEL DE L' EUROPE).

1874.

Time by
Hewitt 890.

Hewitt 890 slow on
Alexandria
Mean Time.

Hewitt 890 slow on
Mokattam Mean
Time, from
above Table.

Alexandria
West of
Mokattam.

."&
*s

h m

m s

m s

m s

Nov. 1 4

12.58

+ .43-92

+ 7. i6-35

5. 32-43

i

*i5

7.42

+ . 43-95

+ 7. 16-95

5. 33-oo

i

*i6

10. 58

+ . 45-60

+ 7. i8'3l

5.3271

21

13.26

+ .48-28

+ 7. 20-85

5.32-57

i

22

13.26

+ -49M-6

+ 7. 22-OI

5. 32-55

i

Combining the values in the preceding Table with the weights assigned,
we have for the Apparent Longitude of Alexandria (Hotel de 1'Europe) "West
of Mokattam Station —

5m. 32'-6o.

This depends upon Captain Browne's and Mr. Hunter's methods of obser-
ving transits of stars, and requires correction also for personal equation in the
method of giving and receiving signals.

* On November i5 the transits at Alexandria are unsatisfactory (the instrument was not reversed).
On November 16 there was no exchange of signals with Mokattam, but good transits were obtained
at Alexandria. The results for November i5 and 16 have each been allowed one-half weight only.

LONGITUDE OF ALEXANDRIA. 329

In the section Longitude of Mokattam (page 285) it will be seen that H gives
signals O'OOS earlier than B, and receives signals Os<062 earlier. On this
account, therefore, the longitude of Alexandria West of Mokattam requires
the corrections + Os<002 and — O'OSl.

After their return to England, viz., in 1875, April, Captain Browne and
Mr. Hunter compared their methods of observing transits in the following
manner : —

The transit instrument that had been in use at Mokattam was mounted in
the grounds of the Royal Observatory, Greenwich, as before mentioned
(page 287), and the beats of the Sidereal Standard Clock were rendered audible
to the observer by introducing a sounder into the circuit connecting the Sidereal
Standard Clock with the chronograph. It was hoped by this arrangement to
obtain the absolute personal equations of both observers, but it was afterwards
discovered that the beat of the sounder was subject to a sensible retardation,
which destroyed the intended comparison with the Greenwich standard ob-
server on those nights, but did not interfere with the relative comparisons of
Captain Browne and Mr. Hunter. The following numbers are the Excess of
the Sidereal Standard Clock Slow, by B and H respectively, over that by the
Greenwich standard observer C + the retardation of the sounder : —

1875. B H

9 8

April 12, + o'5o

13, + 0-41

14, + 0*41

17, + o'2g + o*3g

19. + 0-44

Mean + 0-40 + 0-41

It has therefore been considered that there is no sensible difference between
their methods of observing transits ; consequently no correction is required to
the longitude on this account.

Mr. Hunter having omitted the correction for diurnal aberration, sensibly
08>02 for all clock stars, a correction of — Os>02 is applied to the longitude of
Alexandria West of Mokattam.

We have then for final result —

330 TRANSIT OF VENUS, 1874. EGYPT.

h m s

Apparent longitude of Mokattam, East of Alexandria, as

deduced from the preceding table o. 5. 32'6o

Correction for personal equation between B and H —

8

In giving signals, + o'ooz "i
In receiving signals, — o-o3i /
Correction for personal equation between B and U in the

manner of observing star transits o'oo

Correction for diurnal aberration of clock stars — 0*02

CONCLUDED LONGITUDE of ALEXANDRIA, WEST or

MOKATTAM o. 5. 3z-55

The CONCLUDED LONGITUDE of MOKATTAM STATION,

EAST OF GREENWICH, has been already found 2.5. 6-24

CONCLUDED LONGITUDE of ALEXANDRIA (Hotel de

1' Europe) EAST OF GREENWICH i . 5g. 33'6g

G. L. T.

TRANSIT OF VENUS, 1874.

PART II.

EXPEDITION TO EGYPT

(continued).

Section 3.
OBSERVATIONS AT SUEZ.

By SAMUEL HUNTER, ESQ.

u u

CONTENTS.

Continuation of Mr. Hunter's Letter of Proceedings - - 333

Report of Mr. Hunter on his Observations of the Egress of Venus, 1874,

December 8 - 334

Final Equations inferred from those Observations - - 336

Meridional Transits observed at Suez between 1874, December 3 and 18 - 337

Latitude of Suez - ... - 342

Longitude of Mr. Hunter's Station from exchange of Galvanic Signals with

Mokattam - - 342

Adopted Errors and Rates of the Sidereal Chronometer at Suez - - 343

Comparisons of the Signalling Chronometer used at Mokattam with

the Mokattam Transit-Clock - - 344

Times of Galvanic Signals exchanged between Suez and Mokattam - 345

Longitude of Suez - - 346

Plate XI. — Diagrams illustrating the Internal Contact at Egress - to face 335

333

OBSERVATIONS AT SUEZ.

EXTRACT from a LETTER from Mr. S. HUNTER to the ASTRONOMER ROYAL

(continued from page 322).

SUEZ was reached late on the evening of the 26th November. The next
morning I examined the site occupied by Mr. Gill, of Lord Lindsay's
Expedition,* and rode round the town. Mr. Gill's site was situated in
the lowest part of the town, surrounded by buildings, with the greater
portion of the town between it and the Eastern and Southern horizon (as
it is on the north-western side of Suez), so that the smoke and heated
air from the buildings would most probably prevent definition when the
Sun was so low as at the time of transit ; besides, the Sun would be
hidden by the buildings until 10° or 15° high. I found a small artificial
platform about 40 feet high, on which the Khedive's Chalet is built, situated
on the north side of Suez among the debris of the ancient Arsinoe, which
had a clear Eastern and Southern horizon, free from intrusion and from
smoke. The only defect arose from the looseness of the soil, causing the
level readings to vary a good deal.

The day being Friday, the Mahometan Sunday, I could not prevail on the
Consul to call on the Governor of Suez that day, in order to obtain permission
to erect my hut and instruments at the Chalet ; but next day we called about
ten o'clock, and obtained the necessary permission, and a guard of soldiers to
prevent intrusion. Before night I had all my cases on the platform, the
equatorial pier built, and the hut erected, and on the 30th commenced obser-
vations with the transit instrument. I got a telegraph line erected from
my hut to the office of the Eastern Telegraph Company in Suez, and had
comparisons with Mokattam on December 4, 5, 7, and 14.

Observing with the transit instrument and reducing the observations,
erecting and adjusting the Equatorial, together with the telegraphic com-
parisons, fully occupied my time until the time of the Transit of Venus. On
several mornings preceding I observed the Sun rise (to test my Equatorial,
driving clock, &c.), but to my astonishment I could not get the Sun's image

* Suez was the starting point of Lord Lindsay's chronometric expedition, connecting Suoz,
Mauritius, Rodriguez, and Aden. Lord Lindsay afterwards determined the difference of longitude
between the points occupied by Mr. Gill and Mr. Hunter, thus completing the chain from Greenwich
to Aden.

U U 2

334 TRANSIT OF VENUS, 1874. EGYPT.

defined at all. As I got good definition of stars with it, I examined the colored
glasses, and found that the center of each of them had been partially melted
with the Sun's rays at some previous period ;* consequently they destroyed
the image, so that I had to use a colored glass held in the hand for obser-
vation of contact. The colored glass of the double-image micrometer was
free from this defect.

REPORT of Mr. HUNTER on his OBSERVATION of the EGRESS of VENUS,

1874, DECEMBER 8.

By 4h. 30m. on the morning of the 9th of December I was at my hut, and
had all the arrangements made long before sunrise, although the sky was
almost covered with cloud. A clear strip on the Eastern horizon gave me
the hope of seeing the Sun rise, but even this was covered over just a few
minutes before the Sun rose, so that I did not see the Sun at all until about
half an hour before contact, when I saw it only for a second. In about
10 minutes the Sun was again visible through cloud, and continued visible
until the end, although at times covered so densely with cloud that I had to
remove the colored glass in order to see it. The instant that it became
visible I commenced the measurement of the apparent diameter of Venus,
then the distances from the limb, until it was time to remove the double-
image micrometer and observe contact. The power used for this purpose
= 126, being a positive eye-piece with a glass prism in front of it, forming a
solar eye-piece.

The formation of the ligament took place, without the slightest warning,
at about 5" (by rough estimation) from the apparent limb of the Sun — the
cloud being then rather dense — but good definition. That this was a well-
marked phenomenon is evidenced by the fact that Mr. Isaac Engleson, who
was observing with a telescope of mine outside my hut, and distant about
13 feet (we could not see each other), using a Solar chronometer, noted this
time 18<25 later than I did. His time, reduced to local Sidereal, was
13h. 26m. 53S-90, mine 13h. 26m. 52s-65. At the time we both noted as
follows :— Mr. Engleson : " I think I recorded it 2s. or 3s. late." S. H. :
" Might be a second or a second and a half late," as " I took a second glance
to assure myself that it was not an optical deception." Mr. Engleson had
no previous training on the Model — coming out as a volunteer at his own
cost — and took this as true contact. His time of formation of cusps is later

* The instrument was in Mr. Hunter's possession for five months before he started for Egypt.

Plate XI.

Transit of Venus 1874, at Sue?,.

Fig.].

Fig. 2.

3.

4-

D LtTH.22 BEDFORD ST COVCNT GARDEN.

HUNTER'S OBSERVATION OF EGRESS, AT SUEZ. 335

than mine by 139'66. I estimated true contact at 13h. 27m. 37Sl65, the black
drop being then well marked, and as dark as the body of the planet, cusps
being observed well marked at 13h. 29m. 10s-65. These times are corrected
for clock error and rate.

The rim of silvery light round the edge of Venus on leaving the Sun's
limb was very beautiful and striking, but as soon as I saw that it belonged
to the planet, and likely to last a considerable time, I commenced measuring
cusps with the double-image micrometer. I obtained 8 measures of the
diameter of Venus, 25 distances of limbs, and 75 cusp measures, the whole
of which I regret to say proved useless, as, in determining afterwards the
value of the screw of the double-image micrometer, I found it totally
untrustworthy, as already reported to you.*

The time noted for last contact is very uncertain, the undulations of the
Sun's edge being then very great (all cloud had just cleared off the Sun), so
that the time noted is that when I found myself certain the notch did not
recur, and is consequently too late probably by 5s. or 10s.

Transit observations, the telegraphic comparison on the 14th, and the
necessary reductions, occupied my time until December 24, when I was
enabled to pack up my instruments and hut ready for shipment.

At Suez the Equatorial was situated 11 feet 9 inches due West of the
Transit instrument. From the latter to the nearest (S.E.) corner of the
Chalet the distance was 91 feet 8 inches ; to the Flagstaff, 48 feet 6 inches.

Details of the Observation of Egress.

Times of Phenomena of INTERNAL CONTACT, recorded from the Sidereal

Chronometer Losebtj 102.

h ui s

13. 26. 34, Fig, 1, Plate XI. Just a line, no more.
13. 27. 19, Fig. 2, „ Now well marked.

13. 28. 52, Fig. 3, „ Cusps well marked.

EXTERNAL CONTACT.

13. 56. 15-0. The notch has now become undiscernible.
I tried to get measures several times between this and the last observation,
but the boiling of the Sun's edge from the atmosphere was nearly as great as
the planet's notch, if not quite so.

* Mr. Hunter's micrometer measures have, in consequence, not been published.

336

TRANSIT OF VENUS, 1874. EGYPT.

The definition throughout has been imperfect, clouds continually passing.
I saw the Sun for the first time, for a second, about 15 minutes before the
first observation, and not again until one minute or so before the first
recorded measure. The power used for the observation of contact was 126.
An assistant recorded the time and observations.

For some time after contact, until 13'1. 31m. at least, the edge of Venus was
brilliantly illuminated — that edge which had just left the Sun — so that for a
little I thought the Sun was appearing behind it still, although the cusps
were then well marked, as in Fig. 4, Plate XI. It was a clear silvery light,
like the edge of a cloud.

There was no distortion of the planet during the observation, except at the
first formation of the cusps, when, as seen in the double-image micrometer,
the points were much blunted. No blunted points were observed during the

disappearance of the following limb.

S. HUNTER.

For Mr. Hunter's observations are obtained the following local and
Greenwich times and final equations, assuming the Latitude 29°. 58'. 23". N.,
Longitude 2h. 10m. 13s -17, E. :—

Phase observed.

Recorded
Chronometer
Time.

Correction
of
Chronometer.

Local
Sidereal
Time.

Greenwich

Sidereal
Time.

Local Tabular
Distance
of Centers.

Internal contact . . .

h m a

i3. 27. 19

s

+ 1 8-52

h m s

i3. 27. 37-52

h m 8
II. 17. 24-35

/ //

i5. 41-63

External contact . . .

13.56. i5

+ 1 8-52

13.56.33-52

I I. 46. 2O-35

1 6. 46-37

Taking R = 16'. 16" -82, r = 31'H2, and the Mean Solar Parallax
= 8" -950 (l + j^j). we have for the internal contact—

+ 3"- 77 = -"-2021 n - -2443 8 E.A. -• 9643 8 N.P.D. +"'o342 8 t - 8 K + 8 r,

and for the external contact—

+ i"-87 = — "-2IOO n — -335i 8 R.A. —'9314 S N.P.D. +"'0404 8 t — 8 R — S r.

The transit instrument used by Mr. Hunter at Suez has already been
described in the account of operations at Alexandria. At Suez it was
mounted on a pier of masonry to the S.E. of the Chalet of the KHEDIVE, on
the north side of the town, as described in Mr. Hunter's letter.

MERIDIONAL OBSERVATIONS AT SUEZ.

337

The system of wires remained intact during the observations.

The transits of stars were reduced by Mr. Hunter on the spot. The
Collimation and Azimuth Errors were adopted for each night as found from
the observations of Polaris. The Level Error was not corrected for inequality
of the size of the pivots, as this correction was afterwards determined in
England.

The Clock Error, however, as found by Mr. Hunter, requires no further
correction on account of instrumental errors, since stars were observed with
the transit axis in both positions, and the adopted clock error is the mean of
the two positions of the instrument, irrespective of the number of stars
observed in each position.

The Diurnal Aberration of the Clock Stars is taken into account as a final
correction to the Longitude.

MERIDIONAL TRANSITS observed at SUEZ with the SIDEREAL CHRONOMETER

LOSEBY 102.

1874, December 3.

Star.

"8 8

II

Mean observed
Chronometer
Time of Transit
over the Center
Wire.

Seconds of
True Transit
over the

Meridian.

Seconds of
Star's
Assumed
Apparent R.A.

Chronometer
apparently
Slow.

« 0

PH

h m s

s

s

8

E

O. 1.52*44

32 -6q

55' 2O

+ 22 "5l

E

o. 6. 20-10

25' i5

47-62

22-47

0*eti

E

O. 12. 41 ' 14

4O -QO

3'3i

22*42

E

1.12. 3o-58

6-48

W

I. I I. 5q' 1Q

6-48

W

i. 5q. 44' oo

44.'Q4

7-87

22 "g3

Sidereal Time
of Level

Level Error.

COLLIMATION ERROR.

Determination.

December i, by Polaris, 1-07 (— E, + W).

,, 2, „ 4-97 (- E, + W).

h m

"

„ 3, „ 5-65 (- E, + W) (adopted).

•)

+ 8'58f

o. 55 E

+ 7-80

1.28 W

+ 9'22

AZIMUTH ERROR.

December i, by Polaris and 67 Ceti, — 0-45.

„ 2, by Polaris and /3 Arietis, — 4' 67.

t Mean of 20.

„ 3, by Polaris and i Ceti, — 7-00 (adopted).

TRANSIT OF VENUS, 1874. EGYPT.
Meridional Transits observed at Suez, 1874, December 4.

Star.

Position of
the Micro-
meter Head.

Mean observed
Chronometer
Time of Transit
over the Center
Wire.

Seconds of
True Transit
over the

Meridian.

Seconds of
Star's
Assumed
Apparent K.A.

Chronometer
apparently
Slow.

W
W

w
w
w
w
w

E

E
E

h m a

o. 6. 24*11

0. 12. 40'56

o. 18. 36-36
o. 23. i6'4i
o. 3i. 33-21
o. 36. 56-22

1. I I. 01 -54

1.12. 25-70
1.47.21-79
i. 5g. 45'i5

3

24'99
41-12

37-03
17-01
34-36
56-68

22-11

45-42

8
47-61

3-32
59-47
3g-38
56-83
l8'q5
6-37
6-37
44-26
7-87

s

22-62
22' 2O

22-44
22-37
22-47
22-27

22- l5
22-40

, Ceti

1 2 Ceti

j3 Ceti

Polaris (5)

Polaris (4)

/3 Arietis

a, Arietis

Sidereal Time
of Level
Determination.

Level Error.

Remarks, December 4. Strong wind ; chronometer almost
inaudible.

h in

o. 45 W
I.24E
I.32E

/;

+ 8-55
+ i3-77
+ i i • 5o

Collimation Error by Polaris, 7" -62 (— E, + W) (adopted).
Azimuth Error by Polaris and j3 Ceti, —8"' 21 (adopted).

1874, December 5.

Star.

Position of
the Micro-
meter Head.

Mean observed
Chronometer
Time of Transit
over the Center
Wire.

Seconds of
True Transit
over the
Meridian.

Seconds of
Star's
Assumed
Apparent R.A.

Chronometer
apparently

Slow.

W

w
w
w
w
w

E
E
E
E

h m s

o. 18.37-09
o. 23. 17*06
o. Si.33-86
0.36.56-77
o. 41. 25 '66
. u. 45-84

. 12. I7'70

.38. 26-16
.47.22-48
. 5g. 46 • 06

s

38-04
17-92
35-3g
57-41
26-77

26-55
23 -06
46-66

s

59'47

3q'37

56-83

18-93
48-13
5-3g
5-39
47-76
44-26
7-87

I

21-43
21-45
21-44
21-52

21-36

21'2I
21-20
21-21

1 2 Ceti

j3 Ceti

Polaris (5)

Polaris (4)

o Piscium

|3 Arietis

Sidereal Time
of Level
Determination.

Level Error.

Collimation Error by Polaris, 6" -07 (— E, + W) (adopted).
Azimuth Error by Polaris and |S Ceti, —8" -34 (adopted).

h m

0.28 W
i. 3 W
i.3oE

//

+ 14-43
+ 15-67
+ 14-92

MERIDIONAL OBSERVATIONS AT SUEZ.

339

Meridional Transits observed at Suez, 1874, December 6.

Star.

Position of
the Micro-
meter Head.

Mean observed
Chronometer
Time of Transit
over the Center
Wire.

Seconds of
True Transit
over the
Meridian.

Seconds of
Star's
Assumed
Apparent K.A.

Chronometer
apparently
Slow.

1 2 Ceti

E
E
E
E
E
V?
W
W
W
W

h m s

o. 23. 17-90
o. 3i. 35 *o3
o. 41. 5o- 17
o. 46. i5'6o
i. 12. 33 "o5
i. 1 1. 5g- 19
i. 47. 21 '65
i. 5g. 45-32
2. 6. o-3o
2. 10. 22-92

a

i8'3q
35-86

50-78

l6' 12

23-27
46-96
!-75
24-19

3
39-57
57-02

1 1 -83

37-25
4-82
4-82
44-27
7-86
22-84
45-28

8

21- 18

21 ' l6
2 I • 05

21- 13

21 'CO

20-90

21 '09
21'Og

£ AndromediB

5 Piscium

20 Ceti

Polaris (5)

Polaris (4) .

j9 Arietis

a Arietis

fi Ceti

67 Ceti

Sidereal Time
of Level
Determination.

Level Error.

Collimation Error by Polaris, 5"'8i (— E, + W) (adopted).

Azimuth Error, Polaris and 20 Ceti, — i"'o8 (adopted).
1

h m

o. 55 E

I. 2 E

1.24 W
i.3i W

n

+ i5'33
+ i6-23
+ I7'i3
+ 19-35

1874, December 7.

Star.

1

£•£ i

Mean observed
Chronometer
Time of Transit
over the Center
Wire.

Seconds of
True Transit
over the
Meridian.

Seconds of
Star's
Assumed
Apparent K.A.

Chronometer
apparently
Slow.

2 Ceti

W
W
W
W

E
E
E

h m a

23.56.58'72
o. 1.32-75
o. 6.25-47

0. 12. 41 -94

0.31.35-75
o.36.58'94

I. 12. 0- J2

3

34'83
27- 10
42-98
37-12
5g-o6

8

'9-89
55- 15

47-58
3-28
56 -80
18-91
4'25

8

20-32
20-32
20-48
2O '3O
ig-68

ig-85

a Andromedoe

•v Peeasi .

i Ceti

t AndromediB

)9 Ceti (3)

Polaris (3)

Sidereal Time
of Level
Determination.

Level Error.

Remarks : Observations interrupted by clouds.

AZIMUTH EEROK.

By Polaris and /3 Ceti, —14-0.
By ft Ceti and e Andromeda;, — 8 " o.
By 2 Ceti and a Andromeda^, — 1 1 ' 2.
(Adopted Azimuth Error, — 1 1 • i ).
Adopted Collimation Error, 5' 8 (— E, + W).

h m

o. 18 W
0.54E

if

+ 22-72
+ 23-10

X X

340 TRANSIT OF VENUS, 1874. EGYPT.

Meridional Transits observed at Suez, 1874, December 8.

Star.

Position of
the Micro-
meter Head.

Mean observed
Chronometer
Time of Transit
over the Center
Wire.

Seconds of
True Transit
over the
Meridian.

Seconds of
Star's
Assumed
Apparent It.A.

Chronometer
apparently
Slow.

W

w
w

E

E
E
E
E

h m a

o. 41. 28'g5
o. 46. 17-84

I. 12. 8-02
I. 12. 29- 17

i.3g. 28-87
2. 6. 4- 1 1
2. 10. 26-83
2. 55. 26-47

a
28-96
I7-75

28-46
3-69
26-23
26-I2

8

48-12
37-06
3-66
3-66

47-73
22-82
48-30
45'23

s

19- 16
ig-3i

19-27
19- 13
19-07
19- ii

Polaris (2)

o Piscium

£i Ceti (A.). .

67 Ceti

a Ceti (A.} . ,

Sidereal Time
of Level
Determination.

Level Error.

Collirnatioii Error by Polaris, 4
Azimuth Error by Polaris and

t

'• A.I ( K -I- A

V) (adopted).
• i.

b i)i
0. 15 W
o.55 W
i.3oE
3. 17 E

ii

— O'3o
+ I '12

+ 1-24
+ 5-10

20 Ceti, — 10"

1874, December 9.

Star.

Position of
the Micro-
meter Head.

Mean observed
Chronometer
Time of Transit
over the Center
Wire.

Seconds of
True Transit
over the
Meridiau.

Seconds of
Star's
Assumed
Apparent R.A.

Chronometer
apparently
Slow.

Polaris (3)

w

E
E
E
E
E
W
W
W
W

h m s

. n.5i'8g
. 12. i3'3i
.38. 3o-2g
.47.26-49
. 5g. 5o-o8
2. 6. 5-i6

2. 21. l3'OO

2.29. 0-98

2. 32. 46-81

2. 36. 3i -57

s

3o'og
26'5o
5o'i3

4'94
13-42
i-35
47-07
3i -go

s
3-04
3-04

47' 7-5
44-25
7-85
22-82
3i- 14
19-22
5'o2
49 '86

8

17-64
I7-75
I7-72
I7-88
I7-72
17-87
I7-95
17-96

Polaris (3)

£i Ceti

|2 Ceti

» Ceti

8 Ceti

?2 Ceti

Sidereal Time
of Level
Determination.

Level Error.

Collimation Error by Polaris, 4" '41 (— E, + W) (adopted).
Azimuth Error by Polaris and a Piscium, — 1 4" • 2 (adopted).

h m
o. 8W
o. 10 W
1.25E
2. 8 E
2. i5 W
2.45 W

//
+ 6'oo
+ 4'99
+ 4'69
+ 7-57
+ 9'°7
+ 7-95

MERIDIONAL OBSERVATIONS AT SUEZ.
Meridional Transits observed at Suez, 1874, December 11.

341

Star.

Position of
the Micro-;:
meter Head.

Mean observed
Chronometer
Time of Transit
over the Center
Wire.

Seconds of
True Transit
over the
Meridian.

Seconds of
Star's
Assumed
Apparent R.A.

Chronometer
apparently
Slow.

a Piscium (5)

W
W

w
w
w

w

E
E
E
E

E

h m s

23. 52.36- 15
23.57. 3-32
o. 18. 42-46
o. 23. 22-47
o. 4.6. 20-14
i. ii. 53"o6
i. 12. 18-85
i. 5g. 5o-85
2. 6. 6'oi
2.29. 2'3i
2.55. 28'3i

8

36 -09

2'94
42-31
22-24
ig-95

So-65
5-58
1-81

27-80

s

53 "og

19-87
5g-38
3g'3i
37-04
i '60
i '60
7-84
22-82
ig-22
4.5-23

8

17-00
i6-g3

17-07
17-07
17-09

'7-'9
17-24
17-41
17-43

2 Ceti

A A Piscium

1 2 Ceti

20 Ceti

Polaris (2)

Polaris (2)

a Arietis

f i Ceti

v Ceti

a Ceti (6)

Sidereal Time
of Level
Determination.

Level Error.

Collimation Error by Polaris, 6" '87 (— E, + W) (adopted).
Azimuth Error by Polaris and 12 Ceti, — 14"-6 (adopted).

h m

23. 45 W
i. oW

2.5gE

//

- 1-72
— o-go
+ 5-25

1874, December 14.

Star.

Position of
the Micro-
meter Head.

Mean observed
Chronometer
Time of Transit
over the Center
Wire.

Seconds of
True Transit
over the
Meridian.

Seconds of
Star's
Assumed
Apparent R.A.

Chronometer
appareutly
Slow.

W

w
w
w

E
E
W
E
E
E

h m 8

o. i. 38 '04
o. 6.3o-86
o. 12. 47-01
o. 18. 42 "gi
o. 23. 23-77

1.12. 11-77
I. I I. 43-63

i. 5g. 5i "gi
2. 6. 6-go
2. 10. 2g'8i

9
37-8I

3o'3i
46-02
42-11
22-27

5o-g2
5-65

28-25

8
55-06

47'5i

3'22

5g-38
3g-28
59-07
59-07
7-82
22-78
45-26

s

17-25
17*20
I7-20

47-27
17-01

16*90

I7'i3
17-01

Polaris (3)

Polaris (3)

Ji Ceti

67 Ceti

Sidereal Time
of Level
Determination.

Level Error.

Collimation Error by Polaris, 6"' i3 (— E, + W) (adopted).
Azimuth Error by Polaris and 12 Ceti, —22" '2 (adopted).

h m
22.12 W

23. 55 W
i. 7E
1.55 W
2. i3E

it
— 10-76

- 7-54
— 5-48

xx 2

342 TRANSIT OP VENUS, 1874. EGYPT.

Meridional Transits observed at Suez, 1874, December 18.

Star.

Position of
the Micro-
meter Head.

Mean observed
Chronometer
Time of Transit
over the Center
Wire.

Seconds of
True Transit
over the
Meridian.

Seconds of
Star's
Assumed
Apparent K.A.

Chronometer
apparently
Slow.

W

W
W
W
E

E
E

h m s
I. 11.27-71

i.5g. 55-87

2. 6. II '24
2. 21. ig'54

2.26. 8-54
3.26.52-84
3.33. 7-42

8

56'3o

1 I '20

ig'So
7-72
5i -71
7-20

8

55-87
7'80
22-75

3i' 10
19' 16
3-i8
i8-g5

s

'•5o
•55
•60

'44
'47
•?5

fi Ceti

£2 Ceti

y Ceti

t Eridani

1 1 Taiiri

Sidereal Time
of Level
Determination.

Level Error.

Adopted Collimation Error, 6"'i (— E, 4- W).
Azimuth Error by Polaris and a Arietis, —26" '5 (adopted).

h m

o.3o W

2.25 W

3.2i E

//

— 2' 10
+ 4'20

+ 4'4<5

LATITUDE of MR. HUNTER'S STATION at SUEZ.

From the Admiralty Chart of the Port of Suez, the Latitude of the head of
the Southern Mole, at the entrance of the Maritime Canal, is stated to be
29°. 56'. 3" North.

Mr. Hunter's station, near the flagstaff of the Khedivial Chalet, was 4437
yards north of this point by the said chart, corresponding to 2'. 11"'7 of
latitude. Hence the Latitude of his station was —

29°. 58'. i5" North.*

DETERMINATION of the DIFFERENCE of LONGITUDE between the MOKATTAM and
SUEZ STATIONS by Exchange of GALVANIC SIGNALS.

The observatories at Mokattam and Suez being in direct metallic con-
nection, telegraphic signals were exchanged between them on the nights of
1874, Dec. 4, 5, 7, and 14.

The exchange on each night (with one unimportant exception) was con-
ducted in the following manner : — A positive signal was sent from Mokattam
every 10 seconds, for about 15 minutes, by simply pressing the key in accord-
ance with the beat of a Solar chronometer. The movement of the galvano-
meter needle at Suez was recorded to the nearest tenth of a second by
estimation from the Sidereal transit chronometer. A similar series of positive
signals was then sent from Suez (using the Sidereal chronometer), and
similarly recorded at Mokattam (by means of the Solar chronometer).

* For computing the final Equations for Suez, the latitude was assumed to be 29°. 58'. 23". N.,
which is sufficiently accurate.

LONGITUDE OF SUEZ.

343

Mokattam then sent a series of negative signals, which were followed by a
negative series from Suez, the whole occupying about one hour.

From each series there could be obtained three or more comparisons of
the chronometers when they were apparently beating together, but as each
recorded time was correct within about one-tenth of a second, Captain Browne
has preferred to take the mean of all the recorded times, the total number
of which is shown in the table (page 345).

The Solar chronometer employed at Mokattam was compared with the
transit-clock before and after each exchange of signals. Stars were observed
at both stations on each night, as near as possible to the time of the exchange.

Captain Browne remarks that the results of the different nights are not so
accordant as those obtained in the GREENWICH-MOKATTAM Longitude deter-
mination through the immense length of submarine cable, and attributes it
to the fact that the instruments used at Suez for the determination and
maintenance of local time were not of the high class used at Mokattam. That
may be so ; but there is little to complain of. Thanks to the excellence of
Captain Browne's arrangements, and the consistent accuracy of Mr. Hunter's
work, the Longitude of Suez must be considered to be as satisfactorily
determined as that of Mokattam.

ADOPTED ERRORS and RATES of the SIDEREAL TRANSIT CHRONOMETER LOSEBY 102

on LOCAL SIDEREAL TIME at SUEZ.

Approximate
Local Mean
Time.

Approximate
Sidereal Time.

Transit
Chronometer
Slow.

Loss in
preceding 24h.
Sidereal.

Adopted
Losing Rate.

1874.

b m

h m

a

S

i

Dec. 3, 8. 16

i. 4

+ 2270

••

4, 8. .6

I. 8

+ 22-35

— 0'35

— 0-68 •

5, 8.14

I. 10

+ 21-325

— 1*02

— 0-64

6, 8.19

i. 19

+ 21-075

— 0-25

— o-65

7, 7. 16

0. 20

+ 20-06

— ro5

-0-94

8, 8.21

1.29

+ 19-19

-o-83

— 1-08

9. 9- o

2. 12

+ i7'8i

— 1-34

— roo

11, 7.82

I. 12

+ 17-18

— o-3 1

— 0'2I

14, 7.24

o.55

+ 17-12

— O'O2

-071

1 8, 8.53

2. 40

+ 1 1 '55

— I'Sg

-rig

344

TRANSIT OF VENUS, 1874. EGYPT.

COMPARISONS, at MOKATTAM, of the SOLAR CHRONOMETER FRODSHAM -g-gVs (used
for signalling with SUEZ) with the TRANSIT-CLOCK at MOKATTAM (by coin-
cidence of beats).

Day.

Time by
Frodsham — 3 — r.
(Approx. Local
Mean Time.)

Time by the
Mokattam
Transit-Clock.

Adopted Mokattam
Transit-Clock
Slow on Mokattam
Sidereal Time.

1874.

h m s

h m s

8

Dec. 4

6. 57. 24-5

23. 5o. 48

1

7. o. i6'o

23. 53. 40

f + 2479

7. 6. 35-o

0. 0. O

J

II. I 6. 20'O

4. 10. 26

1

1 1. 19. 20-5

4. 1 3. 27

> + 24-92

I I. 22. 25'O

4. 16. 32

J

Dec. 5

6. 36. ig-5

23. 33. 36

1

6. 3g. 23-o

23. 36. 40

^ + 25-6o

6. 48. 29-5

23.45.48

J

10. 40. io-5

3.38. 17

1

10.43. 25-o
10. 46. 12-5

3. 41. 22
3. 44. 10

I + 25-73

10.49. 20-0

3.47.18

J

Dec. 7

5. 52. 35-5
5. 55. 35-o
5. 58. 36-5

22.57.38
23. o. 38
23. 3. 40

I + 26-gS

g. 55. 25-5

3. i. 8

]

v

g. 58. 25'o
10. i. 44-5

3. 4. 8
3. 7.28

> + 27-05

10. 4.36-0

3. 10. 20

J

Dec. 14

7. 53. 20-0

i. 26. 18

1

8. 5.35-0

1.38.35

8. 8. 3g-5

1.41.40

v + 3i'97

8. 14.38-5

1.47.40

J

10. i.3ro
10. 4. 3o'5

10. 7.40-0

3. 34. 5o
3. 37. 5o
3. 4 1 . o

> + 32-02

ADOPTED HOURLY LOSING RATE of FRODSHAM

3

T!':ins

on MEAN SOLAR TIME,

1874, Dec. 4 +0-024

5 + 0-014

7 + o-o53

14 -t- o'ooS

LONGITUDE OP SUEZ.

345

EXCHANGE of G-ALVANIC SIGNALS between MOKATTAM and SUEZ, and INFERRED

DIFFERENCE of LONGITUDE.

>

AT MOKATTAM.

AT SUEZ.

berofEffe
;nals.

Mean of the
Times by
Frodsham -^'g^
of Sending or

_>

*o
o

i

t-l
0

Mokattam
Sidereal Time.

Mean of the
Times by
Loseby 102
of Sending or

&

3
•a
|

Corresponding
Suez
Sidereal Time.

Suez
East of
Mokattam.

|a

Receiving

-*->

Receiving

S

M

Signals.

i

Signals.

«

1874, December 4, iob.

h in 8

h m s

h m s

h m s

h m s

61

9. 22. O'OOO

S

2. l6. I2'IO

2. 20. 56'774

R

2. 21. 19-09

o. 5. 6*gg

3q

9.37.20727

B

2. 3i. 35'35

2. 36. 2O'OOO

S

2. 36. 42-31

o. 5. 6'g6

79

10. 10. 3o-ooo

S

3. 4. 5o-og

3. 9. 34-694

R

3. 9. 56-gg

o. 5. 6-go

49

10. 26. 42-500

R

3.2i. 5-25

3. 25. 5o-ooo

S

3. 26. 12-28

o. 5. 7*o3

1874, December 5, icA

81

9. 3i. 3o'ooo

S

2. 29. 40-94

2.34. 26-5i5

R

2. 34. 47-80

o. 5. 6*86

58

9. 48. 3o-638

R

2. 46. 44-37

2. 5i.3o-ooo

S

2.5i. 5i-28

o. 5. 6*91

73

10. 4.40*000

S

3. 2. 56-3g

3. 7.42-086

R

3. 8. 3-36

o. 5. 6*97

47

10. 24. 4'83o

R

3. 22. 24-40

3. 27. 10-000

S

3. 27. 3i'26

o. 5. 6*86

1874, December 7, gh.

63

8. 58. 40-000

S

2. 4.40-17

2. 9.26-873

R

2. 9. 46-86

o. 5. 6-69

69

9. 14. 10-579

R

2. 20. i3'3i

2.25. O'OOO

S

2. 25. 19*98

o. 5. 6-67

77

9. 3o. 40-000

S

2. 36. 45-45

2. 4I.32-I89

R

2. 41. 52-i5

o. 5. 6*70

61

9. 46. 45- 1 48

R

2. 52. 53-26

2. 57. 40*000

S

2. 57. 59*96

o. 5. 6-70

1874, December 14, gh.

79

9. o. 5o*ooo

S

2. 34. 3ro5

2. 3g. 20*877

R

2. 3g. 37*g5

o. 5. 6-go

53

9. 1 6. 46-488

R

2. 5o. 3o'i5

2. 55. 20*000

S

2. 55.37*06

o. 5. 6'gi

87

9. 33. 3o-ooo

S

3. 7. 16*42

3. 12. 6-434

R

3. 12. 23-49

o. 5. 7-07

57

9. 5o. o*g32

R

3. 23. 5o-o6

3. 28. 40-000

S

3. 28. 57-04

o. 5. 6*98

We have, therefore, the following mean result for each day for the
Longitude of Suez, East of Mokattam : —

1874, Dec. 4 o. 5. 6-g7o

5. ..... 6*goo

7 6-6go

14 6*g65

346 TRANSIT OF VENUS, 1874. EGYPT.

There does not appear to be any reason for assigning unequal weights to
the above. Their mean is —

oh. 5m. 6"88.

The corrections to be applied to this result for the relative personal
equations of Captain Browne and Mr. Hunter in sending and receiving
signals, and in observing transits of stars, are identical, but with sign
changed, with those already described in the section Longitude of Alexandria,
(page 329), and, therefore, amount together to + Os'03. The Diurnal Aber-
ration of the Right Ascensions of the clock stars, having been omitted by
Mr. Hunter, causes the observed difference of longitude to be too small by
Os>02, no clock stars being very far from the equator. The total correction
is therefore + C^'OS. Hence—

h m 3

CONCLUDED LONGITUDE of SUEZ, EAST of Mo- 1

KATTAM ................... . ............ } °" 5" 6'93

CONCLUDED LONGITUDE of MOKATTAM, EAST of 1 , ..

GREENWICH ............................. 2< 5" 6'2+

CONCLUDED LONGITUDE of HUNTER'S STATION at i
SUEZ, EAST of GREENWICH ................ )

G. L. T.

TRANSIT OF VENUS, 1874.

PART III.

EXPEDITION TO THE ISLAND OF RODRIGUEZ,

IN THE INDIAN OCEAN,

UNDER

LIEUTENANT CHARLES B. NEATE, R.N.

SECTION I.

OBSERVATIONS AT POINT VENUS.
With Two Plates.

SECTION II.

OBSERVATIONS AT POINT COTON.
With One Plate.

SECTION III.

OBSERVATIONS AT HERMITAGE ISLET.
With One Plate.

y y

TRANSIT OF VENUS, 1874.

PART III.
EXPEDITION TO THE ISLAND OF RODRIGUEZ.

Section 1.

OBSERVATIONS AT POINT VENUS.

With Two Plates.

TT 2

TRANSIT OF VENUS, 1874.

PART III.

EXPEDITION TO THE ISLAND OP RODRIGUEZ.

SECTION I.— POINT VENUS.

PAGE
VOYAGE, PERSONNEL, SITE, INSTRUMENTS, AND GEOGRAPHICAL DETERMINATIONS : —

Voyage and Establishment at Kodriguez 351

Personnel 353

Site .353

The Transit Instrument and Clock 354

Equatorial intervals of Wires 355

Collimation 355

Error of Level 355

Error of Azimuth 356

The Altazimuth Instrument 357

Euns of Micrometers 357

Barometer and Thermometer 358

Latitude of the Altazimuth Pier 358

Longitude of Point Venus 358

Longitude from Meridional Transits of the Moon . 359

Longitude from observed Zenith Distances of the Moon 361

Longitude from Occupations of Stars by the Moon 361

Summary of these Results for Longitude 365

Lord Lindsay's Chronometric Expedition to Rodriguez 365

Report of Lieutenant C. B. Neate, R.N., on his Observation of the Transit of Venus,

1874, December 8 365

Equations resulting from these Observations 369

MERIDIONAL AND ALTAZIMUTH OBSERVATIONS AT POINT VENUS IN TABULAR ARRANGE-
MENT : —

Table I. — Collimation of the Transit Instrument 372

Table II. — Error of Level of the Transit Instrument 372

Table III. — Azimuth Error of the Transit Instrument 373

Table IV. — Meridional Transits (abstract) 375

Table V. — R.A. of the Moon's Limb (abstract, united with Table IV.) 375

Table VI. — Longitude of Point Venus from the Meridional Transits of the Moon . . 376

Table VII. — Abstract of Longitudes deduced from Vertical Transits of the Moon . . 377

Plate XII. — Plan showing the position of the Stations on Rodriguez .... to face 352

Plate XIII. — Diagrams illustrating the observation of the Transit of Venus by Lieut. Neate 366

351

VOYAGE AND ESTABLISHMENT AT RODRIGUEZ.

THE Government chartered steam transport Elizabeth Martin sailed from
Woolwich, 1874, May 23, having on board the greater part of the personnel
and stores of the Expeditions intended for Rodriguez and Kerguelen's Land.
She arrived in Table Bay, Cape of Good Hope, June 25, where the Rodriguez
detachment was reinforced by H.M.S. Slwarwater, Commander J. "W. L.
WHARTON, employed in surveying those coasts. Both vessels proceeded to
the Mauritius, where all final arrangements were made, with the cordial co-
operation of the Colonial Government. Here Lieutenant Neate placed
himself in communication with Mr. Charles Meldrum, Director of the Royal
Alfred Observatory, and received much valuable information in regard to
the climate of Rodriguez, and especially to the hurricanes so prevalent there.
Lord Lindsay's Expedition, under the charge of Mr. David Gill, arriving at
Mauritius before Lieutenant Neate's departure, a plan was concerted for
connecting the stations at Mauritius and Rodriguez by the transportation of
Lord Lindsay's large collection of chronometers in H.M.S. Slieanvater.*

The Shearwater, having on board the entire Expedition, arrived at
Rodriguez August 18, and anchored at Port Mathurin.

After a thorough examination of the island, with the courteous assistance
of C. Bell, Esq., the resident magistrate, a good site was selected (to be more
fully described hereafter) on the ruins of an old fort, formerly called FORT
DUNCAN, where foundations could be obtained for all the instruments on solid
rock without digging, and fresh water was abundant at the distance of
300 yards.

Lieutenant Neate writes : —

" Rodriguez is an island of basaltic rock, rising somewhat abruptly from
the sea, and fringed by coral reefs. A level sand-bank, varying in breadth,
nearly surrounds the island, and is dry at ordinary high water. The dis-
embarkation of the huts, instruments, and other heavy stores was necessarily
a tedious operation, and could only be effected at high water. The larger
and heavier cases were hoisted up to the observatory plateau by means of a

* The plan was subsequently carried out ; the Shearwater, starting from Mauritius, twice made
the double journey with the chronometers, arriving at Rodriguez September 13 and 23. The
details of these operations form no part of the present work.

352 TRANSIT OF VENUS, 1874. RODRIGUEZ.

pair of sheers stepped on its edge. The operations of landing and placing
the instruments, huts, &c., were performed by the officers and men of H.M.S.
Shearwater, under the superintendence of Commander "Wharton.

" During the sojourn of the party on the island, observations for local time
were made on every fine night ; the Moon was observed both with the transit-
instrument and with the Altazimuth whenever it was possible. In con-
sequence of the cloudy weather only twelve observations of the Moon on the
meridian were obtained, but on each occasion the clock and instrumental
errors were very satisfactorily determined.

" The Equatorial was mounted in October, but this instrument and the
secondary telescope were very little used before the transit of Venus. A
few occultations of stars were observed ; but little time could be spared by
the observers to ivatch for these phenomena, and consequently only those
occultations whose times of occurrence were known received any attention.

" The Model representing the appearances of the transit of Venus was
mounted in November, and Commander Wharton, Lieutenant Hoggan, and
myself practised with it.

" The Expedition was furnished from the Meteorological Office, West-
minster, with a very complete set of Meteorological instruments. It was
evident at first that to make the necessary observations and entries would
occupy more time than the members of the Expedition could afford. The
offer, therefore, of a local officer, Police-Sergeant Youlton, to take charge
of the Meteorological observations, and to be responsible for the accuracy of
the journal, was very welcome. The various instraments were read twice a
day. The journal was occasionally examined by Mr. Burton or myself.*

" The transit of Venus on December 8 was observed by Commander
Wharton, Lieutenant Hoggan, and myself. Their reports are appended to
my own.

" The Island of Rodriguez was surveyed by the officers of the Shearwater,
under the direction of Commander Wharton. The positions of the secondary
stations on Hermitage Islet and at Point Coton depend entirely upon this
survey. The difference of longitude between Point Venus and Hermitage
Islet was determined by rocket signals in connection with the observations
at both places for local time, but preference is given to the difference
obtained geodetically.

" At my request the Colonial Government at Mauritius (to which Rodriguez

* It is deposited at the Meteorological Office, Westminster.

, -OV7

-°" '~ 71

PERSONNEL AND SITE. 353

is a dependancy) undertook to protect from injury the stone building with,
which I enclosed the transit-hut as a protection against hurricanes, and to
reserve the site for the possible use of subsequent Astronomical Expeditions.

" To conclude, it is only necessary to call attention to the extraneous work
which contributed to the success of the Expedition. The most deserving of
notice is the very efficient service rendered by the officers and crew of
H.M.S. Shearwater, under Commander Wharton, already frequently men-
tioned, by which many great difficulties of landing and transport were
overcome, involving as it often did very hard work. "Without this service
the work of the Expedition could not have proceeded.

" During the stay of the party at the Mauritius much assistance was
rendered by various departments of the Colonial Government in the way of
labour and stores ; and, by arrangement between the Imperial and Colonial
Governments, a dwelling-house was framed, for the residence of the Expedi-
tion at Rodriguez. A schooner was hired to carry the house to Rodriguez.

" Great attention was shown to the members of the Expedition by the
officials.

" The services rendered by Mr. C. Bell and his staff of police were made
the subject of a special communication to the Colonial Secretary.

" C. B. NEATE."

PERSONNEL.

The observing party at Rodriguez consisted of —

Lieutenant CHARLES B. NEATE, R.N., chief ; Lieutenant R. HOGGAN, R.N. ;
and Mr. CHARLES E. BURTON, B.A., of Dublin, who had entire charge of
the Photographic Department, and assisted in the regular astronomical
observations. These observers are distinguished by the initials N, H,
and B, respectively.

Three sappers of the Royal Engineers accompanied the Expedition as
assistant photographers.

THE SITE AT POINT VENUS, RODRIGUEZ.

About three-quarters of a mile N.E. of the little town of Port Mathurin,
on the cliff, some 50 feet above and 200 yards distant from high- water mark,

354 TRANSIT OF VENUS, 1874. RODRIGUEZ. POINT VENUS.

are the remains of an old fort, called on some cliarts Fort Duncan. This was
the site selected, foundations on solid rock being everywhere accessible. The
island, with the extensive coral formation surrounding it, was surveyed by
Commander W. H. L. Wharton, R.N. and the officers of H.M.S. Shearwater
in 1874 ; and on the Admiralty Chart of Rodriguez Island (Indian Ocean),
published 1876, February 16, the site is named Point Venus.

From the Equatorial Stone the following true bearings were found : —

o / //

Apex of Booby Island N. 74. 4. 38 AY.

Apex of Diamond Island S. 76. 1 1. 27 W.

Apex of Diamond Peak 8. 62. 25. 32 W.

The Beacon on -the summit of Le Piton S. 3. 24. 41 E.

Altazimuth Pier, 61 feet S. 77 E.

Transit Pier, 84 feet N. 46 E.

Photoheliograph Stone, 43 feet N. 46 E.

The Transit Pier was 72 feet due North of the Altazimuth Pier.

THE TRANSIT INSTRUMENT AND CLOCK.

The Transit instrument and its mounting were in every respect exactly
similar to those used at Honolulu (see page 9).

The great stone was laid upon a course of bricks, which rested upon the
levelled surface of the solid rock. The instrument was fairly in the Meridian
by August 31. In addition to the wooden observatory brought from Eng-
land, the instrument was protected by a high stone wall, enclosing the
wooden hut.

The adopted value of one revolution of the transit-micrometer-screw, which
carried all five wires of the reticule, is 56" • 30. It is the mean of a great
number of observations of close circumpolar stars at different times. The
integer revolutions of the screw were numbered in the observing books so
as to increase with motion of the wires towards the screw-head ; the center
wire coincided approximately with the optic axis when the reading was
20r-4.

The position of the transit-axis is always denoted by the record of the
micrometer-screw-head being on the east or west side of the telescope.

TRANSIT INSTRUMENT AND CLOCK. 355

The system of .wires remained perfect during the series of observa-
tions.

The Equatorial intervals were found, from 400 transits of time stars, as
follows : —

Wire I. (nearest to the screw-head) + 429*47

,, II. ,, ,, + 2i3'6i

,, HI. ,, ,, o-oo

,, IV. ,, ,, - 212-83

, , V. ,, ,, - 424-70

The mean of the observed times of transit over the five wires is, therefore,
reduced to the center wire by applying the correction i5 gin NpD positive

with micrometer W. The quantity used by Lieut. Neate was i5gi'n]^pD , and,

as the instrument was habitually kept with the micrometer west, in
strictness the times of true transit of all the clock stars require to be
increased 0s '04. This minute correction, -however, has no importance, except
when transferred to the Altazimuth-Clock, in the reduction of the observed
vertical transits of the Moon.

Collimation. — The reading of the Micrometer for coincidence of the center
wire with the optic axis was found by observing temporary and fixed
collimators, or close circumpolar stars, with reversed positions of the
transit-axis (Tab. I.).

The Error of Level was found with the hanging spirit-level, two or more
times each night (Tab. II.). The value of the graduations engraved on the
glass bubble was re-determined by the makers before the Expedition left
England. Thirty-nine divisions were equivalent to one minute of arc, which
value has been used throughout.

The relative size of the pivots was examined by observing the level-error
50 times, the instrument being reversed between each two sets of five deter-
minations. No appreciable difference could be detected.

For the Azimuth Error (Tab. III.) one or more of the stars in the following
list were observed on the center wire, the micrometer-screw being turned as
requisite to enable the star to transit the wire.

z z

356

TRANSIT OF VENUS, 1874. RODRIGUEZ. POINT YENUS.

MEAN PLACES, for 1874 '0, of the STARS observed at POINT VENUS for
AZIMUTH ERROR, as given by Mr. STONE.*

Star.

E. A. 187

4-0. N.P.D.

Lacaille 23

h m s

o. 8. 3o'o4

o / //
I 75. 4. 1 . 4.5 ' Q

o Octantis

o. 1 2. 58'g4

I7Q. 3. 4.8 -Q

Lacaille 248

o. 3g. 5 1 ' g3

176. 23. 3o'2

634. .

1.4.4.. 54-84.

175. 24.. I 8 'A.

764. .

2. 5. 3i '55

ij5. 21. 3o-6

1O2Q

2. 3q. 44' 1 8

176. 16. 24-5

•"y
I 14.6 .

2. 5 I. 33'O4

1 75. 32. 5 1 ' 4

I2O3

3. 3. 58 '89

176. 22. i3"o

i5gz

4.. 6. Q'O4.

175. 37 45-5

2206 .

5.54.38-67

1 74. 5o. 26 ' Q

, 2612

6. 12. 58 '34

1 70. 55. 3i * 7

3274. .

7. 3o. 27 '62

I?6. 4.Q. O" 7

A Octantis . ,

8. 1 1. i5'38

178. 2Q. 5o'7

Brisbane 409 1

12. 33. 10-40

i7Q. 6. 26' 5

z Octantis

H. 28. 5o°OQ

177. 37. 4-O'Q

Brisbane 5607

16. 14. 27' 37

176. 7. O'Q

, , 6o58

17. 40. 38*27

177. 3q. 2o-8

a Octantis

18. 13.38-63

179. 16. 3q'8

B Octantis

21. 2. 14." 14.

I 70. 25. 42 " 2

C Octantis

22. 6. 5o"2O

176. 36. 17-3

T Octantis

23. 8. 4.-QQ

178. IO. 22'3

Lacaille 9696

23. 44. i3'o5

176. 35. 4.Q '3

The Catalogue of 78 Stars was brought up to 1874, January 1, and the loga-
rithms of a, b, c, d and a, V, c, d' computed, before the Expeditions left England.

The Transit clock was originally constructed by Graham for the Royal
Observatory. It was put into good order, and supplied with a cylindrical
zinc-and-steel compensated pendulum by Messrs. E. Dent arid Co., and tested
for many months at the Royal Observatory before the departure of the
Expedition from England. At Rodriguez its rate (Table V.) was not so
regular as it had been during the testing at Greenwich. It was mounted
upon a solid wooden tripod, resting upon the rock, and nowhere touching the
floor of the observatory.

The stars observed for clock-error were taken generally from the list in
use at the Royal Observatory, Greenwich. The Mean Right Ascensions have
been brought up to the beginning of the year from the Greenwich Catalogue
of 2760 Stars for the Epoch 1864. The reduction for the day has been taken
from the Nautical Almanac for all stars found in that work.

The Meridional transits (Tab. IV.) have been reduced as described in

* Places of eight close Southern Polar Stars, Eoyal Observatory, Cape of Good Hope, 1874,
and Catalogue of 78 Stars near the South Pole, Monthly Notices, R.A.S., XXXIII., 55.

ALTAZIMUTH INSTRUMENT.

357

The Meridional transits selected for publication are (1) all stars observed
with the Moon on the meridian ; (2) stars observed in connection with Altazi-
muth observations; (3) stars observed in connection with Lord Lindsay's
chronometric expedition from the Mauritius. The mean determinations of
the transit clock-error are given in Table V., incorporated in Table IV. The
relative personal equations of the observers cannot be determined from the
observations.

OBSERVATIONS OF ZENITH DISTANCE.

The Altazimuth instrument at Point Venus was exactly similar to that
used at Honolulu, described in Part I., page 18. The values of the gradua-
tions on the upper and lower zenith distance levels were 30 and 25 to one
minute of arc respectively.

The system of wires remained perfect throughout the observations.

No imperfect vertical transits have been used.

The Zenith Point corresponding to the Mean of the Wires was l"-7 greater
than that corresponding to the center wire.

The Mean Corrections to the reading of the vertical circle for runs of the
four micrometer screws for 100" were as follows : —

1 874.

Observer.

Correction for
Huns for i oo".

Number
of Ob-
servations.

September 4

N

+ O'22

4

7

B

— o'6o

I

8

H

+ o-o6

4

9

B

+ O' 10

2

ii

B

+ °'47

I

i5

N

+ 0-29

4

24

H

-r o'o6

4

25

B

— o-i5

4

27

Ii

— o'o3

i

28

B

- o-i5

2

October 2

B

— o'o3

2

6

B

— 0-28

2

'9

B

+ o'o5

4

3o

N

+ o-38

3

November 1 7

H

+ o'i3

4

24

N

+ O1 IO

3

December 7

B

— O'2I

2

10

B

— 0'25

2

zz 2

358 TRANSIT OF VENUS, 1874. RODRIGUEZ. POINT VENUS.

On November 13 the object-glass of microscope B, with its cell, was
discovered to be broken away from the body of the microscope. It was
effectively repaired with cement. The observations of November 12 and 13
have, in consequence, been rejected. An examination of the differences of
the means of opposite microscopes, before and after November 13, seems to
show that the accident was discovered soon after it occurred.

A mercurial barometer, by Messrs. Home and Thornthwaite, which had
been tested at Greenwich and found to have no appreciable error, was sus-
pended inside the Altazimuth hut. A verified thermometer was placed
outside on the S.W. side. The thermometer attached to the barometer
generally read 3° higher than the external thermometer ; but it cannot be
thence inferred that the temperature within the hut was higher to that extent
than the external temperature, the attached thermometer not having been
verified.

Satisfactory comparisons of the Altazimuth Clock, Dent 2014, with the
Transit Clock, Graham 2, were made on 56 days.

The LATITUDE of the ALTAZIMUTH PIER.

Numerous observations for co-latitude were made on 42 days, on stars
very near to the meridian, at zenith distances from 10° to 65° ; in one
instance at 75°. The mean results are —

C I If

From 5g stars North of the Zenith, Co-latitude = 70. 19. 38'2 S.
„ 28 „ South „ „ 70.19.37-6

The declinations of the northern stars depend upon observations at Green-
wich ; those of the southern stars upon observations at Melbourne and at the
Cape of Good Hope.

The adopted latitude of the Altazimuth pier is 19°. 40'. 22"-l S.

On the LONGITUDE of POINT VENUS.
(1.) From tJie Observations of the Moon on the Meridian.

The observations have been reduced as described in Part I., page 22. The
results for longitude are exhibited in the usual form in Table VI., from which
are obtained the following means : —

LATITUDE, AND LONGITUDE FROM ZENITH DISTANCES. 359

Observer. J I. Number of Obs. D II. Number of Obs. Mean Longitude,

s s h m s

B 43-z5 4 42-02 4 4.13.42-63

H 3g-88 5 46-36 4 4.13.43-11

N 37-40 i 43-77 4 4.13.40-59

MEAN, POINT VENUS EAST of GREENWICH 4. 1 3. 42-1 1

(2.) Longitude of Point Venus, from the observed Zenith Distances of the Moon.

Kodriguez is not very favorably situated for the application of this method
in the autumn months, the ecliptic being far from perpendicular to the
horizon at the times at which the Moon can be observed, and difficulty was
experienced in obtaining a sufficient number of observations of the Moon's
second limb.

The method of comparing the Altazimuth Clock with the Transit Clock,
and of making and of reducing the Zenith Distance Observations, have been
described in the Honolulu section. The corrections to the Moon's Tabular
R. A. and N. P. D. were taken from the Appendix.

It was not the general practice at Point Venus to observe the vertical
transit of a star near the Moon. The time, determined by one observer with
the Transit instrument, was transferred to the Altazimuth Clock, and was
used by another observer. 178 zenith-distance observations were made on
28 days. For each observation, the Tabular Zenith Distance was computed
from the Nautical Almanac with corrected elements (as explained in the
Appendix) on the two assumptions of longitude 4h. 13m. 10s. and 4h. 14m. 0s.
East of Greenwich. The comparison of these gave a longitude of the station.
An abstract of these results is given in Table VII.

The differences between the Observed and the Tabular Zenith Distances of
the stars observed in vertical transit are collected in the following table.
The series is sufficiently numerous as regards the comparison of times deduced
from Mr. Burton's Altazimuth Observations with times given by Lieutenant
Neate's Transit Observations, and shows a large systematic discordance.

There is some slight evidence of a similar discordance of opposite sign
between Lieutenant Neate with the Altazimuth and Lieutenant Hoggan with
the Transit ; but, neglecting the single comparison on October 2, there are
no observations for estimating the amount of the discordance for the other
four combinations of observers and instruments. It is somewhat singular,
in view of the certainty of the existence of these systematic errors, that the
mean longitude by Altazimuth should be so very near to the mean by the
Transit instrument.

360

TRANSIT OF VENUS, 1874. KODEIGUEZ. POINT VENUS.

COMPARISON of the OBSERVED and TABULAR ZENITH DISTANCES of STARS OBSERVED
in VERTICAL TRANSIT with the ALTAZIMUTH at POINT VENUS.

1874.

Star.

East or
West of
Meridian.

Excess of the
Tabular Z. D.
(with Sign
changed for
Stars East).

Altazi-
muth
Observer.

Transit
Observer.

September 1 4.

a Libras

w

//
— 5'7

B

N

17

a Scorpii

w

+ 1 '2

B

N

October 2

Sirius

E

— 0*4

B

H

16
November 23

8 Sagittarii (Lamp R only) ....
Procyon

W

E

(- i-4)*
+ 2-6

B

N

N
H

25

a, y Leonis

E

+ 5-3

N

H

December 3

Procvon

E

— 2-3

B

N

E Canis Majoris

E

— 2-6

B

N

jS Arietis

W

— 2'Q

B

N

ij1 Orionis

W

— i'8

B

N

5

8 Orionis (Lamp L only)

E

(— 7'i)*

B

N

18 Canis Majoris

E

— 7'2

B

N

£ Ceti

W

— 5-3

B

N

•v Peeasi . .

W

— 8-7

B

N

7

K Orionis

E

— A* 4.

B

N

8 Orionis

E

- \\

B

N

^ Ceti

W

— 3-5

B

N

y Pejiasi . ,

W

— 6'Q

B

N

8

a Pearasi . ,

W

— 3'2

B

N

8 Aquarii

W

— 2'6

B

N

$ Ceti

W

— 3-5

B

N

j9 Canis Majoris

E

— 4'7

B

N

E

— 5'6

B

N

a Hydras

E

— 6-7

B

N

E Canis Majoris

E

— 5'o

B

N

0 Ceti

W

— 6-3

B

N

j3 Canis Majoris

E

— 5'Q

B

N

yS Canis Minoris

E

— 7'5

B

N

tj Ceti

W

— I '2

B

N

* October 16, S Sagittarii. Lamp Left gives — 25"' 8 ; December 5, 8 Orionis, Lamp Bight, gives + 22"' 3.

[The mass of calculations connected with the Altazimuth observations is so
great, and the complete examination of any one by any future investigator
so improbable, that I determined to withdraw from publication all except the
results. The calculations had been most severely checked by Major Tupman,
and the manuscripts are preserved at the Eoyal Observatory. — Gr. B. A.]

The following are the results for the longitude deduced from the observed
Zenith Distances of the Moon, corrected for the constant error of O04 in the
Sidereal time as described on page 355.

LONGITUDE FROM OCCULTATIONS.

361

Observer.

3)1.

Number of Days
of Observation.

3> II.

Number of Days
of Observation.

Mean Longitude.

B

B

h

m

>

N

42

•45

10

32

•79

4

4-

1 3.

37-62

H

49

•27

12

4'

•24

3

4-

1 3.

45-26

B

49-02

7

43-53

3

4-

1 3.

46-27

MEAN,

POINT

VENUS EAST

of GKEE

NWICH

A.

1 3.

43-o5

(3.) Longitude of Point Venus from Occultations of Stars by the Moon.

For the reduction of the occultations, the corrections to the Tabular
Geocentric place of the Moon's center have been taken as follows : —

Correction
to R.A.

Coreection
to N.P.D.

October 1 4,

— o-3o

— 2'2

15,

— o'3o

O'O

17,

— o-33

+ 0-8

November 12,

— 0-40

-f 2-0

16,

— o-3 1

+ 3-5

The calculations have been made as described on page 27, including the
constant reduction of 2"-00 of Tabular Semidiameter.

COMPARISON of CLOCKS and CHRONOMETERS in connection with the

OBSERVED OCCULTATIONS.

Approximate
Local Mean
Solar Time.

||

•

1

Name of the
Solar Chronometer
employed.

Time by
Transit-Clock
at comparison
•with
Chronometer.

Time by Chronometer

Time by
Equatorial
Clock at
comparison
with
Chronometer.

At comparison
with Transit
Clock.

At comparison
with Equatorial
Clock.

1874.
d h

Oct. 14. 4
8

Oct. 1 5. 4
8

8

B

N

B
B

II

Barraud

h m s

1 8. 1 6. 44-0
21.45. i'o

17.08. 53-o
21.49. 4'°

2 1 . 54. 5o-o

h m s

12. 5. 24-5
3. i. 5-o

1 1 . 43. 4 1 -5
3.33. 1 5-o

8. 11.24-8

h m s

n.56. 9-5
2. 47.30-0

u.37. 45-5

h m s
1 8. 3.41-0
21. 27. 34-0

17. 48. 57-0

Carter

Barraud

Barraud

f Parkinson ")
<^ and \
|_ Frodsham j

362

TRANSIT OF VENUS, 1874. RODRIGUEZ. POINT VENUS.

Approximate
Local Mean
Solar Time.

Observer.

Name of the
Solar Chronometer
employed.

Time by
Transit-Clock
at comparison
•with
Chronometer.

Time by Chronometer

Time by
Equatorial
Clock at
comparison
with
Chronometer.

At comparison
with Transit
Clock.

At comparison
with Equatorial
Clock.

1874.
d h

Oct. 1 6. 3
8

Oct. 17. 8
8
8

Oct. 1 8. 10

10

Nov. n. 12
Nov. 12. 10
Nov. 1 3. 12

Nov. i5. 10
i3

Nov. 1 6. 8
10

12

Nov. 17. 9
9

Nov. 1 8. 1 3

N
B

N
H

N

B

N

N
N
N

B

N

B
B

N

B

N

N

{Parkinson ~|
and i
Frodsham J
Carter

h m a

16. 82. 17*0

21.32. 14-0

21. 56. 17-0
21. 58. 25-o

22. II. 35'O

23. 5g. 36-o
o. i. 35-o

3. 12. 23-0

i . 5o. 34-0
2. i5. 3g'o

2. 5. 44-0
2. 7.21-0

h m s

3. 5. 5o'4

2. 40. 2g"5

3. o. 32-5
8. 19. 45-0
8. 32. 53-o

4. 5g. 35*5
10. 1 8. 40-5

11.44. °'5
10. 28. 25-5
10. 49. 3o'o

5. 1 3. 5o'5
10. 33. 20-5

h m s

2. 52. 49'5

10. 22. 3g-5
ii. 58. 19-0
10. 33. 45'o
12. 8.36-5

1 2. 44. 35-5

2. 38. 3o'o
4. 54. o-o
6. 52. 35-5

8.53. 3-o
i3. 25. io-5

h m s
21.44. 7-0

o. o. 56'o
3. 23. 46-0
i. 52. 41-0
3. 3i. 27-0

4. 14. 52'o

23. 29. 38-o
i. 45. 29-0
3. 44. 23'of

o. 3o. 5'oJ
5. 6. 34-0

Carter

Barraud*

]J;iiT;iud. .....

Carter

Barraud

Hewitt

Barraud

Barraud

Carter

Barraud

Carter

Carter

7- 7- 9'5

3. 1 3. io'5
9. 3. 34-5

12.57. 10'5

Carter

4. 3. 2 1 fo

o. 1 3. 45-0
o. 45. 14-0

4. 43. 27-0

Carter

Barraud

Barraud

* Barraud had been recently advanced 4'.

•f Increased io8.

J Error of i". in the comparison with the Equatorial Clock.

LONGITUDE FROM OCCCLTATIONS.

363

-

O

PH

o

03

O
O

s

OQ
O

3

PH

•s

OQ
O

O

O

P
1

Q

01

I

I

—

td

-

i —

^ — ,

co

Tt-

iO

/ — ^

— \

b
— ^0 .

00
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00

Ol

oo

N — CT.

O OO LT5

Vf Vj-ih

1

<*--*• -

*o *o o

M M

rp _-*

cp

O G

CO

C4

C4

«

N W M

w CO

rO

o a.5

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a +

VO

vd

» •« «

m

???

d

m

W

•° t^

00

oo

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VO

IxtsA

^

CTl

N

CO

01

m - -

M

VO VO -

w

CO

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r*

in

r^

00 VO «

o>

CO O OO

N

VO

g CJ

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vb

in

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b

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Equatorial

3 '

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Equatorial
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Equatorial

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Equatorial
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"o
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a

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Achromat

Equatorii
h Eeflecto
Achromal

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a

c

o

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fe 1^84Pil

3 A

364

TRANSIT OF VENUS, 1874. RODRIGUEZ. POINT VENUS.

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o

LONGITUDE, AND OBSERVATIONS OF THE TRANSIT. 365

SUMMARY OF LONGITUDE OF POINT VENUS.

!i m s

By the Meridional Transits of the Moon 4. 13. 42-11

By the Zenith Distances 4. 13.43-05

By the Occupations of Stars 4. 13. 42-52

The preliminary longitude of Point Venus, Rodriguez, obtained by Lord
Lindsay, by the transportation of 42 chronometers between that station and
his observatory at Belmont, Mauritius, is —

4h. i3m. 43" -o.

In this determination the longitude of SUEZ and ADEN were determined by
telegraph signals (that of Suez being given in Part II., Section 3), and the
chronometers were transported from Suez to Mauritius before the transit of
Venus, and from Mauritius to Aden after the transit. These long sea voyages
are fatal to the accurate measurement of Meridian distances by chronometers ;
it is nevertheless highly satisfactory to find such close agreements as the
above.

The final longitude of Point Venus may be assumed to be —

4h. i3m. 428'5 ± is'o.

In computing the final Equations derived from the observations of the
Ingress and Egress of Venus, 1874, December 8, the Longitude of the Head
Station at Point Venus was assumed to be 4h. 13m. 43s • 0. Hence the error
of the Greenwich Sidereal Time is 8 t = + 0s "5.

G. L. T.

OBSERVATIONS OF THE TRANSIT AT POINT VENUS.

NEATE'S OBSERVATIONS OF INGRESS.

The instrument used by Lieutenant Neate was an Equatoreal, with object
glass of 6 inches aperture, driven by clock-work, constructed for the expe-
dition by Messrs. Troughton and Simms. It was fitted with double-image
micrometer and solar diagonal reflector, as represented in Plate III. The
equatoreal mounting was supported by an iron pillar, which at Rodriguez
stood upon a foundation of brickwork laid on the rock. It was protected by
a portable wooden observatory, constructed at Greenwich. A sidereal clock

3A 2

366 TRANSIT OF VENUS, 1874. RODRIGUEZ. POINT VENUS.

(Dent 2014), with pendulum rod of wood, accompanied the instrument, and
was mounted in the Equatoreal hut.

The following is Lieutenant Neate's Report of the observations.

OBSERVATIONS OF INGRESS.

For several days previous to the transit I practised observing the Sun
with the Equatoreal, and established the focal adjustment as accurately as
I could. On two mornings also I observed the Sun under conditions exactly
similar to those which I anticipated for the actual transit. On the morning
of December 9, a little before sunrise, I prepared the Equatoreal hut, tried
all the eye-pieces and double-image micrometer in the instrument, tested the
driving clocks for the last time, and assured myself generally that all was
ready. By the kind permission of Mr. Bell, the resident magistrate, the
observatory was surrounded by policemen, and no one was allowed to
approach. My assistant on the occasion was Navigating Lieutenant
Hammond, of H.M.S. Shearwater, who sat at a table in the Equatoreal hut,
and wrote from my dictation in copying ink.

Half an hour before the first phenomenon I compared the Equatorial Clock
with the Transit Clock.

The sky was unusually clear of clouds, and the heat of the Sun made itself
felt very soon.

I did not see the planet till it had (apparently) broken into the Sun's limb.
Instantly when I saw the notch on the Sun's limb I also saw the remaining
segment of the planet showing in strong relief against the dark space beyond,
and surrounded by an exceedingly faint annular haze. The following limb of
the planet also appeared bright, like a very young moon. This appearance
I have attempted to show in Fig. 1, Plate XIII. I used an Airy eye-piece,
power 152, for the observation of all phenomena. The dark glass I used was
a neutral tint achromatised wedge. The first phenomenon recorded by me
was that of Circular or apparent Contact at llh. 51m. 24s '5 by the Equatorial
Clock, as shown in Fig. 2. The formation of a dark ligament between the
limbs of the Sun and Venus followed instantaneously. It was as if, after
Circular Contact, a piece of Venus was being drawn out by the Sun.

The breadth of this ligament was apparently one-fourth (approximately) of
Venus' diameter.

The next phenomenon noted by me was the change of colour in the
ligament, which at IP. 51m. 51s • 5 became a light-greyish brown. The change

Plate XIII

Transit of Venus 1S74 Dec. 8.

Observations at, Point Veruis, Rotbiytte^ by Lieutenant Neale>R.N. *iit/t. a
TeLescope of 6 inches aperture power 1o2.

s, Fii). /.

Ingress, Pig. 2.

Ingress Fit) 3 .

Egress, fig- /•

Egress, .Fig. 2.

NEATE'S OBSERVATION OF THE TRANSIT. 367

was apparently very rapid and well-defined. I have noted it to a fraction of
a second. In Fig. 3 I have attempted to show this second phenomenon noted
by me, but the ligament appears broader than it should be. The definition
during these phenomena was exceedingly good, but the conditions changed
very rapidly, and the Sun's limb began to boil considerably, so much so that,
although I placed the double-image micrometer in the telescope as soon as
the planet had left the Sun's limb, I only secured two measurements of
distances of limbs, which are not recorded here, as the definition of the planet
was extremely bad, and the micrometer-zero was uncertain. I, however,
noticed that the following limb of the planet was apparently illumined,
partaking somewhat of the appearance it had when outside the Sun ; this
lasted for nearly five minutes after the planet had completely entered on
the Sun.

I now proceeded to compare the Equatorial and Transit Clocks. I also
compared the Transit and Altazimuth Clocks. The heat in the Equatoreal
hut very soon became so great that I was unable to sit at the telescope, the
Thermometer in the hut (but shaded) standing at 115° Fahrenheit. I was
very nearly having a sunstroke, and was obliged to lie down for an hour.
Shortly before the phenomenon of Egress I again compared the Transit,
Equatorial, and Altazimuth Clocks, and then placed myself at the telescope.
The definition was now bad, the atmosphere appearing very disturbed ; but
about ten minutes before the second Internal Contact a big cloud passed
across the Sun, and slightly cooled the atmosphere, and the definition was
improved. The proximity of clouds, however, deterred me from using
the double-image micrometer for measuring distances of limbs ; nothing,
however, interfered with my observations of Contact and accompanying
phenomena.

The first phenomenon noticed by me at Egress was the formation of a
brown haze between the two limbs ; and in spite of the apparent dancing of
the limb of Venus and the boiling of the Sun's limb, this formation appeared
instantaneously at 15h. 21m. 27s '2, and in appearance it resembled closely
what I had seen at Ingress in the second noted phenomenon. In Fig. 1 at
Egress I seemed to see a repetition of Fig. 3 at Ingress, with the difference
of inferior definition at Egress. The ligament gradually deepened in colour
(maintaining the same breadth) till Internal Contact (Fig. 2, Egress) was
formed at 15h. 22m. 24s • 8. This phenomenon was fairly well-defined, although

368

TRANSIT OF VENUS, 1874. RODRIGUEZ. POINT VENUS.

not so well as the first Internal Contact had been. I was, however, enabled
to note it to the fraction of a second.

I now put in the double-image micrometer, intending to make measure-
ments of cusps ; but clouds prevented my making more than two measure-
ments. I, therefore, replaced the Airy eye-piece, and I was fortunate enough
to catch sight of the planet about three minutes before it disappeared ; and
the last phenomenon I noted was the disappearance of the little black notch
in the straightening of the Sun's limb at 15h. 50m. 28s '0, and immediately
afterwards I compared the three clocks as before. On the planet leaving the
Sun I failed entirely to see what I had seen at Ingress, namely, the preceding
limb on the external segment of the planet projected against the dark space
beyond. With reference to the dark ligament, to which I have alluded,
I may mention that at no time did it appear perfectly black ; even immediately
succeeding and immediately preceding the first and second Internal Contacts
respectively it was a degree less dark than the planet. In this particular
it differed from that which, according to my impression, the " Model " pheno-
mena showed. During " Mid-transit " I examined the planet with various
eye-piece powers, and it appeared to me to have a very slight ellipticity, the
greatest diameter being inclined about 30° to the path of the planet.

COMPARISONS of the EQUATORIAL CLOCK MOLYNEUX with the TRANSIT CLOCK
GRAHAM 2, by the intervention of the SOLAR CHRONOMETER CARTER 410.

Day and
Approximate
Local Mean
Solar Time.

Time by
Transit Clock
at comparison
with
Chronometer.

Time by Chronometer at
comparison

Time by
Molyneux at
comparison
with
Chronometer.

Inferred
Molyneux
Slow on Local
Sidereal Tune.

Adopted
Hourly
Losing
Rate of
Molyneux.

With
Transit Clock.

With
Molyneux.

1874.

h

h m s

h m s

h m s

h m s

in s

s

Dec. 8, 12

4. 46. 1 3"O

6. 19. 55-o

7. 19. io'o

5. 44. 8'0

+ 0.53-56

18

«9

10.44. 9'°
12. 6.33-0

o. 1 7. 5o*5
i. 40. o-5

o. 19. 58'0

I. 44. l6'0

10. 46. 45-0

12. 1O. J7'0

o. 55-ig
o. 55-5i

+ O'3 1 O

23

16. 0.37-0

5. 33. 24-5

5. 3o. 24-5

i5. 07. i3-o

+ o. 46-69*

* An error of 10". in one of the readings.
The chronometer Carter was losing 7s -5 daily on mean solar time.

NEATE'S OBSERVATION OF THE TRANSIT.

369

From Lieutenant Neate's telescopic observations we obtain the following
results : —

Assuming Latitude 19°. 40'. 21'H ; Longitude 4h. 13m. 43S-0 East.

Phenomena Observed.

Recorded
Time.

Local
Sidereal
Time.

Greenwich
Sidereal
Time.

Local Tabular
Distance of
Centers.

INTERNAL CONTACT at INGRESS.

h m s

ii. 5i. 24-5
1 1. 5 1. 5 1 -5
ii. 52. 14-8

h m s

1 1. 52. 19-92
ii. 52. 46-92
ii. 53. io-23

h m s

7. 38. 36-gi

7.3g. 3-gi
7.39.27-22

/ //

1 5. 3g'6o
1 5. 38-75
1 5. 38-oo

Change of colour of ligament

INTERNAL CONTACT at EGRESS.

Formation of ligament

if). 21. 27*2

i5. 22. 44-8

l5. 22. 22-y

1 5. 23.40-3

II. 8.39-7
II. g.57-3

15.41-27
15.43-81

EXTERNAL CONTACT at EGRESS.

Disappearance of the planet

i5. 20. 28-0

i5. 5i. 24-65

I I. 37.41-64

16. 43-78

For the " disappearance of the ligament " at Ingress, taking R = 976"'80,
r — 31"-42, we have the equation —

+ 7"-38 = +"-1937 n — -6io38R.A. — -7498 8N.P.D. — o"-o3o6 S t — I R + S r.

For the " formation of the ligament " at Egress, taking E = 976"'82,
r = 31"-42, we have—

+ 4"-i3 = —"-0274 n —-2176 S R.A. —'9718 8 N.P.D. +o"-o322 8< — 8R + 8r.

The final longitude being O5 further East than that adopted in computing
the Greenwich Sidereal times above, a correction is required to these
equations, which is obtained by making 5 t = + Os-5.
8 R.A. is expressed in seconds of arc.

G. L. T.

371

OBSERVATIONS

AT

POINT YENTJS, RODRIGUEZ,

IN TABULAR ARRANGEMENT.

3 B

372

TRANSIT OF VENUS, 1874. RODRIGUEZ.

TABLE I. — COLLIMATION of the TRANSIT INSTRUMENT at POINT VENUS.

Day.

1874.

Sept. i
i

12
it
it

>9

21
21

22
22
25
25

Oct. 19
•4

Object.

Collimator

Reflected Wires .

Collimator

ff Octantis

Collimator

Collimator

Collimator

Collimator

Collimator

r Octantis

c Octantis

r Octantis

Collimator

o Octantis

Reading of Micrometer for
Zero of Collimation.

Observed.

r

20-389
20-389

20-381
20-385
20-377
20* 402
20-384
20-377
20-385
20-374
20-392
20-388
20-382
20-372

Adopted.

r
| 20' 389

2o-38o
20-380
2o-38o
2o-38o

20-384
38o

J2o-

20-38o
20-38o

Day.

1874.

Oct. 26

26
27
27
3o

Nov. 1 6
24
27
28

Dec. 7
7

Object.

Lacaille 634 .
z Octantis . . .
Lacaille 1029
Lacaille I2o3
Collimator. . .
Lacaille 1 592 .
Collimator. ..
Collimator. . .
Lacaille 3274
Lacaille 1592

Collimator

z Octantis . . .
Collimator. . .
Collimator . . .

Reading of Micrometer for
Zero of Collimation.

Observed.

10-378
20-376
20-398
20-327
20-379

20- 395
20-398
20-389
20' 376
20-370

20-386
20 • 400
20-383
20- 3g3

Adopted.

r

J2o-38o

l-2o-38o

20- 3 80
20- 370
20- 390
20-390

2O' 390

20-3S5

20-383
20-388

TABLE II. — EREOR of LEVEL of the TRANSIT INSTRUMENT at POINT VENUS, determined by

SPIRIT LEVEL.

[The sign + indicates that the East Pivot was low.]

Day.

Sidereal Time of

Level
Determination.

Error of Level.

Day.

Sidereal Time of

Level
Determination.

Error of Level.

1874.
September i

2

i3

"9

h m

20. O

21. 45

2. IS

2.45

3.26

o. o

1 6. 27

17. 5

18. 3o

19. 34
19.55
i 8. l5

20. 3o

22. I 8
22.40

23.3o

0-9

2'O

l874.

September

+ 3-5

+ 2-6

+ 3-3

+ 1-6

+ 6-3

+ 6-9

23

- 4-3

- 3-o

- 2-9

- 2-8

— 1-2

— O'2

- 0-7

+ 0-1

October

h m

19. 33

19. 55

20. 23
21.23
23.25

o. 20

20. 5

21. 55
23.i5

0. 35

1. 3o

2. 3o

5. 57
6.28
7. o
7.40

— i -o

+ 0-2
+ 0-2
- 0'4

+ 0-7

— o- 1

- 0-4

O'O

o-o

- 0-9

ERRORS OF TRANSIT INSTRUMENT, IN COLLIMATION, LEVEL, AND AZIMUTH.

373

Table II. — Error of Level of the Transit Instrument at Point Venus — concluded.

Day.

Sidereal Time of
Level
Determination.

Error of Level.

Day.

Sidereal Time of
Level
Determination.

Error of Level.

1874.
October 20

h iii
21. 50

- 0-9

1874.
November

24

h .,.

4.25

> t

+ 2'6

o. 40

o-o

5.45

+ 3'8

23

23. 3o

— I 'O

6.35

+ 4'2

24

o. 35
23. 3
o. 3o

+ 0'2
+ O'2

+ i'7

25

4. o

6. 20

6.25

+ 5'3
+ 7-1
+ 5-6

25

26

0. 20
2. 30

o. 40
i.3i

i. 55

+ 1 '0
+ 2'2
— O'2

+ 0'7
+ 1-3

28

6.25
7.40
8.35
9. 3o

+ 3'2

+ 5-2

+ 5'2

2. 40

— O'2

December

7

2. O

- 0-6

3.25

+ 2' I

3.4:

+ i'5

3. 35

+ 1-9

4- '7

O'O

27

2.45

O'O

4-35

+ I 'O

3. 1 5

+ o-5

5. 35

+ I "i

28

3.45
4-53
5. o

+ 1-6

+ 1-9

— O' I

8

i. 5o
3. 40

O'O

+ I- 1

29

2. 10

+ 0'2

4. 20

5.20

+ 2-4

November 1 6

21. 30

+ 2'5

5. 5o

+ 1-9

23

o. 5o
4. 10
4- 5
5. 5o
7. 3o

+ 3'4
+ 4'7

9

i. 5o
3. o
4. 3o
5.25

+ 2-7
+ 3-6

+ 10-9
+ i3'o
+ i3'8

TABLE III. — AZIMUTH ERROR of the TRANSIT INSTRUMENT at POINT VENUS.

[The Sign + signifies that the Optic Axis points East of North.]

Day. Stars.

Azimuth Error.

Observed.

Adopted.

1874.
September

i z Octantis S.P. a
2 T Octantis and a

1 3 Least Squares . .

+ 6i-3

+ 59-4

+ 6i-3
+ 59'4

+ .4'2

+ 16-8

19 A Octantis S.P.
B Octantis and jf

— II'O

- 8-8

3 B 2

374 TRANSIT OF VENUS, 1874. RODRIGUEZ.

Table III. — Azimuth Error of the Transit Instrument at Point Venus — concluded.

Day.

Stars.

Azimuth Error.

Observed.

Adopted.

1874.
September

October

November

December

21 A Octantis S.P. and o Cygni

B Octantis and e Pegasi

C Octantis and f Pegasi

22 A Octantis S.P. and B Octantis

C Octantis and ij Aquarii

r Octantis and K Piscium

23 B Octantis and o Cygni

o Octantis and 26 Ceti

z5 C Octantis and o Aquarii

r Octantis and i Piscium

I ff Octantis S.P. and Sirius

20 C Octautis and A Aquarii

T Octantis and o Pegasi

o Octantis and £ Ceti

23 o Octantis and p Andromeda?

z Octantis S.P. and Lacaille 634

24 r Octantis and K Piscium

o Octantis and o Andromedse

25 o Octantis and 20 Ceti

26 2 Octantis S.P. and Lacaille 634

27 Lacaille 1029 and/Tauri

Lacaille izo3 and e Eridani

28 Lacaille 1203 and e Eridani ,

29 Lacaille 1 146 and a Arietis

Lacaille I2o3 and o Tauri

Lacaille 1 592 and f Tauri

1 6 Lacaille 248 and yl Eridani

Lacaille 1592 and 37 Tauri ,

23 Brisbane 6o58 S.P. and Lacaille 25 12 ,
<r Octantis S.P. and Lacaille 25 12 ...

24 Lacaille 2296 and e Orionis

Lacaille z5i2 and a Orionis

25 Least Squares ,.

28 Lacaille 3274 and i\ Cancri

7 Lacaille 764 and z Octantis S.P

Lacaille 1 592 and * Tauri

Lacaille 634 and z Octantis S.P

Lacaille 1592 and a Tauri

9 Lacaille 634 and f Ceti

Lacaille 1146 and Brisbane 5607 S.P.

5-9
4-8
6-6

2'4

4'0

6'2
2' I
I ' I

0-8

2'0

6-4
2-9
2-5
1-9

0-8
0-4
3-8

2-8
3-3
3-3

2'6

1-9
6-6
6-3

-5o-8
-49-3

-55-9
-61-7

- 8-4

4-6

5'2

4'9
4-0
4-8
4-8

- 4-1

- 0-9

— 2'O

- 2'5

- 3-8

+ 3-o

+ 2-4

+ 1-8

- 6-4

— 5o-o

-54-9

- 8-4

4'6
4'8
5-3

In the instances marked " Least Squares " Clock-Errors have been formed by use of all the Clock-Stars observed in the day,
each containing the Azunuthal Error as an uuknown quantity ; and the magnitude of the Azimuthal Error has been deter-
mined so as to make the sum of squares of residual discordances minimum.

TRANSITS OP STARS AND MOON, AND R.A. OF MOON'S LIMB.

375

ABSTRACTS of TABLES IV. and V. — TRANSITS of STARS aud of the MOON, and Inferred R.A. of the

MOON'S LIMB at TRANSIT.

a

^ a

a °

•g

o •

I's.

K

II

i-lrf

Clock Slow

Clock's

a
§

Clock Time of

Right Ascension

Day,

1874.

Ii

» 22

II*

& M

on Local
Sidereal

Losing
Rate.

Transit of Moon's
Limb over

of Moon's Limb
at Transit

.0 ^

"a B

a £

Time.

.n 5

Meridian.

over Meridian.

i's

|°o^

5 o O

a w

5

s

a

h 1.1

B

h m >

h

September i

7

i

2.42

+ 46-68

+ 9-9

n.

3. 24. 8-40

3. 24. 55-29

/ Least 1

i3

5

\ Squares /

17.19

+ 9-14

+ 1-55

H

7

i

18.58

+ 10-81

+ 2-21

'7

6

2

19. 25

+ 19-94

+ 3-3o

'9

8

2

19. 8

+ 27-45

+ 3-68

i.

18. i5. 14-40

18. 15.41-65

21

4

2

21. 5o

+ 34-56

+ 3-oo

i.

20. 16. 18-46

20. 16. 52-82

22

12

4

19.45

+ 37'i3

+ 2-92

i.

21. 1 6. 1-34

21. 16.38-75

23

12

I

21. 34

+ 40-33

+ 3-44

i.

22. 14. 59-38*

....

1.42

+ 40-99

+ 3-53

25

II

3

23. 5

+ 45-24

+ 2-99

i.

o. 5.38-17

o. 6.23-55

ii.

o. 7.56-67

o. 8.42-05

October i

7

i

7- 9

+ 59-35

+ 2-oS

ii.

6. 10. 12*04

6. n. n-32

2

3

i

i. 36

+ 60-93

+ 2-II

16

6

I

x3. 16

+ 32-89

+ 2- 3o

17

5

i

23.43

+ 35-3o

+ 2-27

20

4

3

23. 1 8

+ 42-38

+ 2 -2O

i.

21.46. 22-33

21.47. 4' 55

23

8

3

o. 39

+ 48-83

+ I -80

i.

o. 3i. Si*79f

o. 3i. 40-55

24

n

2

0. 21

+ So- 54

+ 2-l5

i.

1.26. 55-86

i. 27. 46-40

25

7

I

I. 12

+ 53-20

+ 2-59

i.

2.25.38-57

2.26. 3i-8i

•

11.

2.28. 3-35

2.28.56-61

26

7

2

1.54

+ 55-58

+ 2-67

n.

3. 3o. 16-16

3.3i. i2-3i

27

10

2

3.55

+ 58-84

+ 2-58

n.

4. 35. 41*48

4. 36-40-38

28

i

O

5- 9

+ 6i-38

+ 2-62

ii. 5.42.44-74

5. 43.46-19

29

7

3

4.36

+ 64-16

+ 2-55

ii.

6.48. 5i-5i

6. 49. 55-93

November 1 6

7

3

4-35

+ 3o-63

+ 0-84

i.

21. 25. 14*20

21. 25.44-42

23

8

3

5.33

+ 16-42

- 0-78

i.

4. o. 12-95

4. 0.39-33

24

5

2

5.20

+ 25-92

- o-57

ii.

5. 7.51-28

5. 8.17-08

25

6

f Least ]_
\ Squares )

5. 3

+ 25-29

- 0-87

ii.

6.16. 38-i5

6.17. 3-46

28

3

i

7- 17

+ 22-52

— o- 10

ii.

9. 22. J.3'25

9.22. 35-65

December 7

5

3

3.42

+ 24 ' 1 1

— 0-46

8

ii

4

4. 12

+ 23-54

— o- 59

9

9

3

3. 4I

+ 22-85

— 0-62

* No farther step is taken in the computation of the observation of September 23. I am not aware of the reason. — G. B. A.
f Apparently an error of i'".

376

TRANSIT OF VENUS, 1874. RODRIGUEZ.

TABLE VI. — LONGITUDE of POINT VENUS, RODRIGUEZ, from the MERIDIONAL TRANSITS of the MOON.

.0

a

Observed K.A.

Longitude (East)

Correction

Corrected

Day.

B

'A

f

of the

by the Epheineris,

to the

Longitude,

^_;

Remarks.

1

o

Moon's Limb.

4b. i3m. +

Epheineris.

4h. 1 3'". +

•z

0

s

fc

1874.

h in s

s

i

September i

B

2L

3. 24. 55-29

60-94 + 24- 1 66 e

•84

40-6

I

'9

B

i L

18. iS. 41-65

56-04 + 24- i3i f

- '32

48-3

I

21

N

iL

20. 1 6. 52-82

46-88 -f 23 -8046

- -40

37-4

I

22

B

iL

21. 16. 38-75

5o-86 + 24-432 e

- '44

40- 1

I

25

B

iL

o. 6.23-55

57-39 + 26-063 e

- -66

40-0

I

25

B

2L

o. 8.42-05

59-53 + 26-048 e

- -66

42-3

I

Defective Limb (o"-oo).

October i

B

2L

6. ii. 11-32

63-26 + 2Z-452e

- '9»

42-6

I

20

a

iL

21.47. 4'55

46-71 •*- 25-66l €

- -42

35-9

i Four Wires.

23

H

i L

o. 3i. 40-55

52- 54 + 26-096 f

- -58

37-4

J One Wire only.

24

B

i L

i. 27. 46-40

60-90 + 24'354 f

- -67

44-6

i

25

H

iL

2. 26. 3i-8i

58-67 + 23-798 e

- -76

40-6

i

Defective Limb (o^S).

25

H

2L

2.28. 56-6i

69- 14 + 23-798 e

- -76

5i-o

i

26

N

2L

3.3i. i2-3i

62-97 + 22-482 f

- -82

44-5

i

27

B

2L

4. 36.40-38

61 -43 + 21 -6o3 (

- "87

42-6

i

f¥our Wires. Clock

28

N

2L

5.43.46-19

66-35 + 21 -459 t

- -90:

47-0

i

•< correction unsatis-

[ factory.

29

H

2L

6.49.55-93

6o-58 + 22-223 e

- -86

4i-5

i

'

f Clock correction un-

November 16

II

iL

21. 25.44-42

46-75 + 26-226 6

— -3i

38-6

^ 1 certain. Stars with

the Moon.

23

H

iL

3.58. 7-3o

6O'OO + 21 "796 f

- -69

45-0

i i Defective Limb (o"'oi).

23

H

2L

4. 0.39-33

60- 16 + 21 -772 (

- -69

45-'

i i

*4

N

2L

5. 8.17-08

56-86 + 20-960

- '77

40-7

i

25

H

2L

6.17. 3-46

64-93 + 21 -084 e

- -81

47-8

1

28

N

»L

9.22. 35-65

66-17 + 26-710 €

- -81

44-5

i

-

LONGITUDES OF POINT VENUS, FROM LUNAR TRANSITS AND ZENITH DISTANCES. 377

TABLE VII. — ABSTRACT of LONGITUDE of POINT VENUS from the observed ZENITH DISTANCE

of the Moox.

1874.

Number of Obser.
rations.

Correction to
Longitude
for Error of
Sidereal Time.

Mean inferred
Longitude
for each day,
corrected,
4h. 1 3'". +

ja
to

i

1874.

Number of Obser-
vations.

Correction to

Longitude
for Error of
Sidereal Time.

Mean inferred
Longitude
for each day,
corrected,
4h. i3m. +

4
1

Observer, N. Moon's i L.

Observer, B. Moon's i L.

September 1 8

2

+ 1-29

36-29

65

September 1 7

4

+ 1-38

5o-28

85

October 17

8

1-27

46-3i

i3i

18

2

1-29

45-58

66

'9

4

i-3o

3o-38

8?

21

2

1-24

47-83

75

22

2

I '36

37'i3

9i

October 16

6

1-28

51-92

112

24

4

i'3o

36-22

IOJ

18

3

1-27

54-17

68

November 14

4

1-28

5o-37

87

20

7

i-34

5?-i8

95

i5

8

1-32

53-22

124

23

8

+ i-35

4i-3i

161

16

6

i-36

Ji-aS

92

18

4

1-42

34-20

58

'9

4

1-42

35-70

126

22

2

+ i-2i

50-07

?5

Mean with weights, 4''. i3m. 42" '45.

Mean with weights, 4''. i3m. 49"'O2.

Observer, N. Moon's 2 L.

Observer, B. Moon's 2 L.

i

B

•

i

October 27

5

+ 1-14

33-47

n5

September 27

6

+ 1-29

40-79

1 60

29

6

i'i5

42-35

87

October 26

2

I 'OO

36 -89

65

November 24

8

1' IO

17-73

in

26

4

+ I'OO

56-52

67

25

2

+ I • IO

3o-32

57

Mean with weights, 4h. i3m. 32"- 79.

Mean with weights, 4h. i3'".43"53.

378

TRANSIT OF VENUS, 1874. RODRIGUEZ.

Table VII. — Abstract of Longitude of Point Venus from observed Zenith Distances of the Moon — concluded.

i

Mean inferred

i

Mean inferred

1874.

£

O

<M

o •/:

Correction to
Longitude

Longitude
for ea<Sh day,

1874.

i

o
*4

Correction to
Longitude

Longitude
for each day,

Number
vation

for Error of
Sidereal Time.

corrected,

4h. 1 3°°. +

3

ftK

"8

*

Number
vatior

for Error of
Sidereal Time.

corrected,
4". i3m. +

S

tc

i

Observer, H. Moon's i L.

Observer, H. Moon's 2 L.

September 19

3

s
+ 1-25

43-07

68.

September 26

12

s

•f 1-34

42-36

226

20

2

1-23

47-66

70

November 24

8

i • 10

41-08

125

21

4

1-24

48-25

io5

25

2

+ I- JO

3S-67

42

22

4

1-27

49-72

163

25

2

i-35

42-25

97

October 22

2

i-36

55-90

42

24

2

i-3o

5o-5o

80

November 14

4

1-28

52-8i

85

i5

8

1-32

53-32

125

16

6

i-36

61-81

89

18

4

1-42

41-45

56

'9

2

+ 1-42

43 -3o

89

Mean with weights, 4h. i3m. 49" 27.

Mean with weights, 4h. 1 3m. 41" 24.

TKANSIT OF VENUS, 1874.

PART III.
EXPEDITION TO THE ISLAND OF RODRIGUEZ

(continued).

Section 2.

REPORT OF COMMANDER ¥. J. L WHARTON, RE, ON THE
OBSERVATIONS AT POINT COTON.

With One Plate.

3c

CONTENTS.

PAGE

1. On the positions of the Secondary Stations at Rodriguez . . . . „ . . 381

2. Comparisons of the Chronometers with Clocks at Point Venus .... 382

3. Times of Rocket Signals 382

4. Intel-comparisons of Chronometers 383

5. Errors and Rates of the same 383

6. Observations of the Transit of Venus, 1874, December 8 384

Plate XIV.— Diagrams illustrating the Observations of the Transit of Venus, by

Commander Wharton to face 384

POSITION OF STATION AT POINT COTON. 381

REPORT of COMMANDER W. J. L. WHARTON, R.N., on the POSITIONS of the
SECONDARY OBSERVING STATIONS in RODRIGUEZ and on his own OBSERVATIONS
of the TRANSIT of VENUS, December 8, 1874.*

1. POSITIONS of the SECONDARY OBSERVING STATIONS.

These positions were determined by triangulation from the primary station
at Point Venus.

A base line of 2,503 feet, situated on the flat sand-covered coral reef, was
measured, at low water, six times by means of two chains. The greatest
difference was 2 feet.

This base was expanded by five well-proportioned and carefully observed
triangles to 9882'3 feet, and from this last base three systems of triangles
were started, all of which terminated at the Hermitage Islet, and one system
terminating at Point Coton.

The theodolites employed had Azimuth circles of 8, 7, and 5 inches. No
triangle was accepted the sum of whose angles differed more than 1' from
180°. From the conformation of the island some ill-conditioned triangles
were unavoidably admitted into the system, but the small angle was invariably
at one of the known stations. To this circumstance, however, a part of the
discrepancy in the result is due ; but as the first system, although the best
in point of number and in the forms of the triangles, entailed longer dis-
tances than could be accurately measured by the power of the small
theodolites, the arithmetical mean of the three results for Hermitage Islet
has been taken. From this point 12 true bearings were taken which differed
1^' among themselves.

The following are the results : —

Distance of the station on Hermitage Islet (marked H on the Survey Plan) from the station
(marked S) at Point Venus —

By the first system, 6 triangles, 26835-6 feet South, 621 3-4 feet East.
By the second system, 6 triangles, 26824-9 ,, ., 5z3o-5 „ „
By the third system, 12 triangles, 26845-1 „ „ 52i5'8 „ „

Mean 26835-2 ,, „ 5220-0

* The details of Commander Wharton's surveying operations in the Island of Rodriguez are
deposited in the Hydrographic Department at the Admiralty.

3 c 2

382

TRANSIT OF VENUS, 1874. RODRIGUEZ. POINT COTON.

Applying corrections of a few feet at either end for the distances between
the survey stations and the astronomical stations, and taking the geographical
mile as 6,053 feet, Lieut, Hoggan's telescope was 4'. 25"'6 S. and Om. 3S>59
East of the Altazimuth Pier at Point Venus.

Similarly my own station at Point Coton was 0'. 32"'3 S. and Om. 168'98
East of the Altazimuth Pier, Point Venus.

2. COMPARISONS of CHRONOMETERS with the CLOCKS at POINT VENUS.
The chronometers employed at Point Coton were —

Baker No. 1083 Box, 2-day.

Poole No. 1086 Box, 2-day.

Molyneux No. 2280 Pocket-box, 2-day.

They were compared with the Transit and Altazimuth Clocks at Point Venus,
before and after transportation to Point Coton, as follows : —

Approximate
Local Mean Time,
1874.

Time by
the Transit
Clock.

Corresponding
Chronometer
Time.

Chronometer
Compared.

Corresponding
Chronometer
Time.

Time by
the Altazimuth
Clock.

h

h m 3

h m a

h m s

h m 3

Dec. 7, 23

16. 20. 46-0

l6. 22. IO-O

16. 25. o-o

8. ii. 3-5

2. 29. 38-o
6. 5i. 20-0

Baker
Poole
Molyneux

8. i3. 3ro
2. 34. 56 -o
6.57. 10-8

16. 23. o'o
16. 27. 17-0
1 6. 3o. 3g-o

9, o

17. 34. 5o-o
17.36. o'o

17. 37. 2O'O

g. 21. 3'o
3. 3g. 16-1
7. 5g. 26-0

Baker
Poole
Molyneux

9. 23. 7-5
3. 42. io-5

8. 2.32-2

17. 36. 38-o
17.38. 38-o
17. 40. iro

3. TIMES of the bursting of ROCKETS sent up from MOUNT SIMON,
simultaneously observed at POINT VENUS and at POINT COTON.

Approximate
Local Mean Time,
1874.

At Poiut Venus

At Point Coton

Time by Transit Clock.

By Poole.

By Baker.

Observer (Neate).

(Hoggan)

(Burton).

Observer (Wharton).

Observer (Langdon).

h

December 8, 8

1) m s

i. i5. 38'4
i. 19. 7-0

I. 23. 22'g

i. 36. 1 6-9

8

38-o

7-1

22'4

16-6

s

37'9
6-4

22'6

.6-.

h m s

5. 4. 2g'6
5. 7.58-0
5. 12. 12-4
5. 25. 5-o

h m s

ii. 21. 36-7
1 1. 25. 5'o

1 1. 42. 12-0

CHRONOMETER COMPARISONS.
4. INTERCOM? ARI SONS of the CHRONOMETERS used at POINT COTON.

383

Approximate
Mean Time.

Observer.

Time
by Baker.

Time
by Poole.

Time
by Molyneux.

1874.
h m

Dec. 8, i. i3

7.67
8.36
17.46
18.01

22. 0
22.32

9, i. o

W
> j
> >
> >

9 >
) 5
» >

L

h m s

10. 8. 5r3

h m a

4. 26. o-o
4. 28. o'o
ii. 10. 26'6

II. 12. 5-0

i i.5o. 167
1 1 . 53. 5-o

g. o. io'o
9. i. o'o
10. 5. 3o-o

IO. 6. 20'0

i. i3. 3o-o
i. 1 5. 3o-o
i. 45. o-o

i . 46. 40-0
4. 14. 36'o

h m s

8. 46. 53'0

4. 53. 2o-o

3. 3o. 57-2

5. 33. i o-o

4.11.57-0

i. 19. 5o'6

2.43. 5'8

3. 48. 26-0

2. 25. IO'3

5. 34. ig'6

6. 56. 26-4

7. 27. 56-5

6. 5. 29-5

9. 67. 32-5

5. ERRORS and RATES of the CHRONOMETERS used at POINT COTON.

Name of
Chronometer.

Approximate
Local Mean Time.

How Compared
with Transit Clock.

Chronometer
Slow on Point Venus
Mean Time.

Loss in 24''.

Baker

1874.
h m

Dec. 7, 23. 14

Direct Comparison.

h m s
+ 3. 2. 37-02

a

8, 8. i5

By Rockets

+ 3. 2.36'io

- 3-ii

Poole

9, o. 24
7, 23. i5

Direct Comparison.
Direct Comparison.

+ 3. 2.33-75
— 3. 14. 32-71

8, 8. i5

By Rockets

— 3. 14. 3rog

+ 3-02

Molyneux ....

g, o. 25
7, 23.18
8, 8. i5

Direct Comparison.
Direct Comparison.
By Rockets

— 3. 14. 29-54
+ 4. 26.34-81
+ 4. 26. 37-08

+ 6-25

9, o. 26

Direct Comparison.

+ 4.26.41-32

W. J. L. WHARTON.

The chronometer Poole was used for recording Captain "Wharton's observa-
tions during the Transit of Venus. It will represent the mean of all three if
its correction be taken as follows, remembering that Point Coton station was
168-98 East of Point Venus :-

h m s

At Internal Contact at Ingress, 3. 14. 12 'jgfast* on Point Coton Mean Time.
„ „ Egress, 3. 14. 12*62 fast „ „

G. L. T.

* In the Report presented to Parliament, 1877, July 16, the chronometer Poole was erroneously stated to have
been slow on L. M. T.

384 TRANSIT OF VENUS, 1874. RODRIGUEZ. POINT COTON.

OBSERVATIONS at POINT COTON, RODRIGUEZ, by Commander WILLIAM J. L.
WHARTON, R.N., with a 2f Refractor by Troughton and Simms.

The observation spot was 20 feet from the edge of the sea cliff (30 feet) of
Point Coton that faces the East, with the summit of the inshore cliff (where
the triangulation beacon was) S. 73°. 03' "W. (true) 185 feet. The northern
point of Point Coton is (by chart) 926 feet. By triangulation, the position
was 0'. 32"-28 South and 4'. 14"'69 (diff. long.) East of the Altazimuth Hut
at the main observatory on Point Venus.

The exact spot is marked by an iron stake fixed into the rock with lead.

On the 8th December three chronometers were conveyed to Point Coton
by water, after being compared with the Transit clock of the Point Venus
observatory ; intercomparisons on arrival showed they had suffered no shocks.

Time was checked the same evening by rockets thrown up in the center
of the island ; two hours after the transit, the chronometers were again com-
pared with the Transit clock, having been re-conveyed by water to Point
Venus.

Time was taken by Nav. Lieut. Langdon, R.N., from the Solar chronometer
Poole 1086.

The morning of the 9th was perfectly calm, and generally clear, but several
clouds hung to the S.E., and threatened to cover the Sun at the moment of
contact. About a minute after the critical phenomenon the Sun was hid
from view for some minutes. The limb of the Sun was considerably agitated,
probably by the rays passing through the thinner portions of the clouds
above-mentioned ; as the line of sight passed over no land, and the surf on
the reef at 300 yards distance was quiet.

The planet was first seen at 9h. 28m. At 9h. 52m. I observed that the outer
limb of Venus farthest from the Sun was illuminated ; as I was not on the
look out for this, it may have been visible earlier. At the same time I saw
a distinct cone of shadow thrown away into space, but for no great distance,
on the line joining centers of Sun and planet. (See Diagram I.)

The illumination of the outer limb of Venus broadened and increased in
brilliancy up to simple internal contact, when for a moment it seemed as if
there was to be no drop ; Venus being apparently visible on the edge of the
Sun, with light all round her. (See Diagram II.)

Immediately after this a blackish haze was discernible joining the planet
and the continuation of the Sun's limb ; but from the agitation of the limb,

Transit uf Venus. 1874.

Observations at Point Colon , Rodriguez, by Commando- W.J.L.W}uirton,KN.
with a telescope of 2? inches aperture, power J60.

Ingress, Fig. 1 •

Ingress . Fig. 3.

Ingress, Fig. 2

Egre&s, Fig. 4.

r:tLO lltH 22 BfOfOKD Sr CovIMI

WHARTON'S OBSERVATIONS OF THE TRANSIT. 385

this haze was not distinctly defined, and did not seem to change colour
before disappearance. The moment of total disappearance of haze was
tolerably defined, but I could not be certain to two or three seconds. The
band of haze did not narrow at all before it broke, so far as I could see.

Venus on the Sun did not appear to me to be perfectly round. The
eccentricity took the form of a protuberance in a direction about 20° farther
from the vertex than the point of contact. Of this I would not be certain,
but it so appeared to me.

At Egress the limb was much less disturbed than at Ingress. The brown
haze appeared quickly, though not well defined at its edges, as a ligament ;
it was of considerable breadth, and after a few seconds darkened perceptibly ;
the exact instant of this was not very well marked.

When Venus' outer limb touched the Sun's limb, the appearance of light
all round again was visible for a second.

The limb protruding into space was then again illuminated for nearly
seven minutes ; when 'the light gradually died out from the quarter nearest
the vertex, leaving only the other quarter illuminated. This remained so for
14 minutes after Egress, or until nearly half the planet was clear of the
Sun. (See Diagram 4.)

The power was 160, and the dark shade was a red glass of not a very deep
tint.

I should say that Point Coton was undoubtedly the best position for the
observation of the transit ; but from the nature of the reef skirting it, it
woiild have been impossible to get heavy instruments and stores landed
without much risk and delay, not having any flat bottomed boats for the
service ; and there is no road nor path from Port Mathurin.

OBSERVATION of the TRANSIT.

At Ingress.

Times by Chronometer
Poole 1086.

h m i

First saw Venus 9. 28.

Observed outer limb of Venus outside Sun illuminated 9. 52.

Observed cone of shadow 9. 53.

The^outer limb of Venus being illuminated, there seemed to
be no black drop for a few seconds ; when that limb came
in contact with the visible Sun light shone all round Venus.
Time for this 9. 55. 26-4

386

TRANSIT OF VENUS, 1874. RODRIGUEZ. POINT COTON.

Time by Chronometer
Poole 1086

A moment after, a black haze was discernible, but from the
great agitation of the Sun's limb (the morning being some-
what cloudy) it was not distinctly defined, and did not
visibly change colour. The moment of total disappearance
of black hazy drop as nearly as could be guessed was 9. 57. 3-0

At Egress.

Agitation of Sun's Limb not so great.

First appearance of brown haze 1. 25. 39'6

First appearance of black hazy drop, not very distinctly

marked 1. 25. 48'1

Appearance of light all round the planet at circular contact ... 1. 26. 26'9
The illumination of the outer limb disappeared from the whole

arc of the planet outside the Sun, and was confined to the

quarter farthest away from the vertex at about 1 . 30. OO

Disappearance of illumination from the quarter of Venus

farthest from vertex 1. 40. 40

With the corrections of the chronometer Poole 1086 given on page 383,
assuming the Latitude 19°. 40'. 54", Longitude 4h. 13m. 599>5 East of
Greenwich, we have the following results of Commander Wharton's obser-
vations : —

Phenomenon observed.

Recorded Time

by Solar
Chronometer
Poole 1086.

Local

Sidereal

Time.

Greenwich

Sidereal

Time.

Local Tabular
Distance of

Centers of Sun
and Venus.

Internal Contact at Ingress.

" Simple internal contact "

" Total disappearance of black hazy
drop."

h m s

9. 56. 26*4
9. S/. 3'o

h m a
1 I. 52.54'3

ii. 53. 3ro

h m s

7. 38. 54-8
7. 3g. 3r5

1 5. 3g'oi
15.37-86

WHARTON'S OBSERVATIONS OP THE TRANSIT.

387

Phenomenon observed.

Recorded Time
by Solar
Chronometer
Poole 1086.

Local
Sidereal
Time.

Greenwich
Sidereal
Time.

Local Tabular
Distance of
Centers of Sun
and Venus.

Internal Contact at Egress.

h m s

h rn s

h m s

/ //

" first appearance of brown haze " -

i. 25. 3g-6

l5. 22. 41*7

II. 8.42-2

I5.4I-36

"First appearance of black hazy
drop."
" Circular contact " -

I. 25.48-1
I. 26. 26-9

l5. 22. 5o'3

i5. 23. 29-2

II. 8. 50'8
II. 9.29-7

1 5. 41*64
i5. 42*91

For Internal Contact at Ingress, " Total disappearance of black hazy drop,"
taking R = 976"-80, r = 31"-42, and mean solar parallax = 8"'950 (l + ^),
we have the equation —

+ 7"-52 = + o"- 1 935 n - -6 1 02 8 R. A. - -7500 8 N.P.D. — o"-o3 1 3 8 t - S R 4 %r.

For Internal Contact at Egress, " First appearance of brown haze ," taking
B, = 976"-82, r and n as before—

— -2I788E.A. — '97I78N.P.D. +o"-o332

G. L. T.

3 D

TEANSIT OF VENUS, 1874.

PART III.
EXPEDITION TO THE ISLAND OF RODRIGUEZ

(continued).

Section 3.

REPORT OF LIEUTENANT ROBERT HOGGIN ON THE
OBSERVATIONS AT HERMITAGE ISLAND,

With One Plate.

3o 2

CONTENTS.

PAGE

Observing Station, and Operations for Longitude 391

Latitude and Longitude of Hermitage Station 391

Double altitudes of the Sun observed for local time 392

Rocket Signals 393

Intercomparisons of Chronometers 393

Errors and Rates of Chronometers 394

Observations of the Transit of Venus, 1874, December 8 395

Equations resulting therefrom 399

Plate XV. — Diagrams illustrating the Observations of the Transit of Venus by

Lieutenant Hoggan to face 395

POSITION OF STATION AT HERMITAGE ISLAND. 391

Lieut. R. HOGGAN'S OPERATIONS at HERMITAGE ISLAND, RODRIGUEZ.

THE small islet on the south side of the Island of Hodriguez, named on the
Admiralty charts Hermitage Island, having been selected for the position
of a secondary telescope for observation of the actual Transit of Venus,
Lieut. Hoggan, accompanied by Lieut. "W. N. Moore, R.N., of H.M.S.
Shearwater, proceeded there on the 30th November 1874, taking with him a
4-inch refracting telescope by Dollond, with tripod stand, two sextants,
a mercurial artificial horizon with cover, and the two box chronometers —

Hewitt 732

also the " pocket " chronometer Parkinson and Frodsham No. 4530, beating
five times in two seconds.

Lieuts. Hoggan and Moore remained encamped on the islet until
December 10. The errors of the chronometers on local time were determined
by a continuous series of observations of equal altitudes of the Sun from
December 3 to December 9. At 8 p.m. on December 2, 6, 8, and 9, five
rockets were sent up from the summit of Mount Simon (by a party from
H.M.S. Shearwater). These rockets were visible from Lieut. Hoggan's and
Captain "Wharton's stations as well as from the head station aj; Point Venus.
The instants of the bursting of the rockets were noted independently by
Lieut. Neate and Mr. Burton at Point Yenus, and by Lieuts. Hoggan and
Moore at Hermitage. For various reasons the observations of December 2
and 6 were rejected. In the meantime, Captain Wharton connected the
station on the islet by a system of triangles with the general survey of the
island, as fully described in his Report (page 381).

From this triangulation the station on Hermitage Islet was 4'. 25"'6 South
and Om. 39<59 East of the Altazimuth pier at Point Yenus. The Latitude of
Hermitage Station is therefore 19°. 44'. 47"'7, and the Longitude 4h. 13m. 46s- 1
Bast of Greenwich.

By comparing the errors of the three chronometers on local mean solar
time, as determined from the equal altitudes observed on December 7 and 9,
with their errors on Point Yenus mean time, as determined from the well-
observed rocket signals on the evening of December 8, the difference of
longitude between the two stations appears to be 3S>87, a proof of the

392

TRANSIT OF VENUS, 1874. RODRIGUEZ. HERMITAGE ISLAND.

accuracy of the observations for local time made on the islet. The adopted
Longitude of the Hermitage Station is 4h. 13m. 46S>1 E.

The details of observations on December 7, 8, and 9 only have been
selected for publication.

EQUAL DOUBLE- ALTITUDES of the SUN observed with a SEXTANT at HERMITAGE
ISLAND, RODRIGUEZ, and INFERRED ERROR of the POCKET CHRONOMETER
PARKINSON and FRODSHAM No. 4530.

[The approximate Index Correction to Sextant Reading was found to be — 2'. 5o",
and the Collimation adjustment was satisfactory.]

Civil Day,
1874.
(Observer.)

Recorded Time
by Parkinson and
Frodsham,
Sun East.

Reading of
Sextant
and Limb of
Sun.

Recorded Time
by Parkinson and
Frodsham,
Sun West.

Parkinson and
Krodsham Slow on
Local Mean
Time at Apparent
Noon.

h m a

o /

h m s

m 3

December 7

(M)

8. 49. 57-0
8. 52. 1 8-0

99- °U
99. o L

2. 40. 3o-o
2.38. 9-0

+ 6. 22-96

8.54.17-4
8. 56. 3g-2

101. o U
101. o L

2. 36. 9-6
2. 33. 47-6

+ 6.23-01

8. 58. 37-6
g. o. 5g-8

io3. o U
io3. o L

2.3i. 48-5

2. 2g. 27-0

+ 6. 23-20

g. 7. ig-5
9. 9.41-2

107. o U
107. o L

2. 23. 6-3

2. 2O. 45-6

+ 6. 23-21

g. 1 1. 40-0

jog. o TJ

2. 18. 46-4

, -

g. 14. 1-6

log. o L

2. l6. 25-0

O. 26 10

g. 1 6. 0-6
9. 18. 22-8

in. o U
iii. o L

2. 14. 26-0
2. 12. 4-6

+ 6. 22-82

Q. 20. 21'5

1 13. o U

2. 10. 6-2

'

.7

+ 6. 22-53

g. 22. 42-8

u3. o L

2. 7.44-6

(H)

g. 3i. 12-0

118. oU

. 5g. 1 6-4

,

'

g. 3i. 33-o

118. 10 TJ

. 58. 54-0

g. 3 1 . 55-o
g. 32. i5-6

118. 20 TJ
1 18. 3oTJ

. 58. 32-o
.58. 9-6

+ 6. 23-ig

g. 32. 37-2
9. 32. 58-8

118.40 TJ
ii8.5oU

• 57. 49-6
.57.27-6

• + 6. 23-og

g. 33. 20-4
g. 34. 3'2

ug. o TJ
ug. 20 U

. 57. 6-0
. 56. 21-6

1+6. 23-44

g. 34. 47-2
g.35. g'o

ug. 40 U
i ig. So U

.55.38-8
.55. 16-4

1+6. 23-3g

g. 35. 30-4
g. 37.52-7

120. O U
120. 0 L

. 54. 54-4
. 52. 35-2

1+6. 23-07

December g

(M)

8. 37.41-6
8.40. 4-8

g3. o U
g3. o L

2. 54. 33'0

2.52. 10-8

1+6. 22-09

8.42. 3-2
8. 44. 24-8

g5. oU
g5. o L

2. 5o. IO'5

2.47.48-2

> + 6. 22-92

8. 46. 25-2
8.48.46-8

97. oU
97. o L

2. 45. 49-2
2.43. 27-2

1+6. 22-49

CHRONOMETER COMPARISONS AND ROCKET SIGNALS.

393

TIMES, simultaneously recorded at POINT VENUS and at HERMITAGE ISLET, of
the bursting of ROCKETS sent up on MOUNT SIMON.

AT POINT VENUS.

AT HERMITAGE ISLET.

Approximate

Transit Clock Times.

Times by

Times by

' Mean Time.

Chronometer

Chronometer

Observer

Hewitt.

Parkinson
and Frodsham.

(N.)

(B.)

(W.)

(L.)

Observer (H).

Observer (M).

1874.

h

h m a

3

8

8

h m s

h m 3

December 8, 8

. 8.32-0

32-0

7. 54. 6-0

7. 53.4I-2

. i5. 38-4

37-9

8. i. io-5

8. o. 46*0

. 19. 7-0

6-4

8. 4. 3g-3

8. 4. 14-2

. 23. 22-9

22-6

8. 4. 54-0

8. 8. 29-3

. 36. 1 6-9

16-1

8. 21. 45-9

8. 21. 21'2

9, 8

. 14.32-9

32-3

32'4

33-o

7.56. 7-8

7. 55. 44-5

. ig.55-8

55-i

55-2

55-7

8. 1.29-6

8. i. 6-4

. 24. 36-i

36-i

36-o

36-o

8. 6. 9-9

8. 5.46-4

.29.42-1

42-1

42-1

42-1

8. 1 1. 14*4

8. 10. 5r6

. 34. 42-0

4''9

41-6

4''9

8. 1 6. i3-3

8. 1 5.5o-i

INTERCOMPARISONS of CHRONOMETERS at the HERMITAGE ISLET.

Approximate
Civil Time,
1874.

Observer.

Time
by Hewitt.

Corresponding
Time by
Parkinson and
Frodsham.

Time
by Hewitt.

Corresponding
Time by
Cotterill.

h

h m t

h m s

h m 8

n m a

Dec. 7, 9 a.m.

H

8.42.38-0

8. 42. i3-o

8. 46. 55-o

8. 45. 45-5

noon

0. 8. 23-0

o. 7. 58-o

o. 6. 56-o

o. 5. 45-7

3 p.m.

[H -P&F.25-0]

10 p.m.

10. 4. 3o-o

10. 4. 4-8

8, 8 a.m.

B

8. 19. 41*0

8. 19. i5-8

8. 22. ig-o

8.21. 4-5

noon

o. 10. 49-0

o. 10 23-8

o. 1 5. io'o

o. 1 3. 54-6

7 p.m.

7. 22.40-0

7. 22. l5'2

7.27. 9'o

7. z5. 52-3

9, 5am.

H

5. o. 29-0

5. o. 6-0

5. 5. 7-0

5. 3. 48-4

7 a.m.

7. 1 6. 34-0

7. 16. 1 1 -2

7. 3i. 19-0

7. 29. 59-9

8 a.m,

8. 28.09-0

8.28. 26-3

i o a.m.

9.45. ro

9. 44. 38-2

9. 25. o'o

9. 23. 40-0

1 1 a.m.

10. 43. 53-o

10.43. 3o-3

10.48. i5-o

10.46.55-3

noon

11.58. 7-0

1 1. 57. 44-3

O. O. 2O'O

n.5g. o-o

3 p.m.

2. 5g. 25-o

2. 5g. 2-0

7p.m.

7. 14.32-0

7- '4- 9'°

7.22. ro

7. 20. 3g-g

8 p.m.

8. 27. 34-0

8. 27. iro

394 TRANSIT OF VENUS, 1874. BODRIGUEZ. HERMITAGE ISLAND.

ADOPTED ERRORS and BATES of the CHRONOMETERS at HERMITAGE ISLET.

BY THE OBSERVED EQUAL ALTITUDES.

BY THE ROCKET SIGNALS.

1874.

Chronometer
Slow on Local
Mean Time.

Loss
in 24h.

1874.

Chronometer
Slow on Point
Venus Mean
Time.

Loss
in 24h.

Hewitt No. 732.

m s

s

h m

W S

S

Dec. 7, apparent noon

+ 5. 58-04

8,

+ 0-86

Dec. 8, 8. 12

+ 5. 54-91

9, apparent noon

+ 5.59-77

9, 8.12

+ 5.56-iS

Cotterell No.

Dec. 7, apparent noon

+ 7- 8-34

8,

+ 5-71

Dec. 8, 7.33

+ 7. ii-58

+ 5-65

g, apparent noon

+ 7- '977

9, 7. 38

+ 7. 17-20

Parkinson and Frodsham No. 4530.

Dec. 7, apparent noon

+ 6. 23-04

8,

— 0-28

Dec. 8, 8. 12

+ 6. 19-67

— o-32

9, apparent noon

+ 6. 22-47

9, 8. 12

+ 6. ig-35

For the Ingress of Venus the pocket chronometer Parkinson and Frodsham
No. 4530 may be considered 6m. 21s-96 slow on Local Mean Time ; for the
Egress, 6m. 228-35 slow on Local Mean Time. This chronometer will then
represent the mean of the three as well as the mean of both methods of
determining the local time.

Observation of Ingress.

On the morning of the transit, before sunrise, the sky was cloudless, and
the atmosphere so very clear that stars could be observed rising from the

Transit of Venus 1674 Def ember S.

tfosetvations at Htrmitfige Islet, Rodrigue^ by Lieutenant R. Hoggan,, R.N, with a telescope
of 4- inches aperture , pmver 120 for Ingress, 160 far Ecjress.

Plate

Ingress Fig. 1.

Ingress Fig. 2.

Ingress Fig. 3.

Egress Fig. /.

Egress Fig. 2.

Egress

egress Fig. 4-. >,:,tpmioui»v2 B^ORO ST CO

HOGGAN'S OBSERVATIONS OF THE TRANSIT. 395

sea horizon ; but when daylight broke some very thick black clouds appeared
near that point of the horizon where the Sun was rising.

The Sun rose through a break in the clouds, and remained visible until he
had attained an altitude of about 10°, when a very light breeze sprang up
and swept the clouds slowly across his face, totally obscuring it. The time
of external contact at Ingress had passed about eight minutes before the Sun
reappeared, and when first I observed Venus she appeared with one-fourth
of her disc on the Sun.

There seemed to be a very great amount of atmospheric disturbance,
making the limbs of the Sun and Venus appear in a state of very rapid
vibration. At this time I was using the lowest power in the telescope
(about 70).

In about a minute's time the Sun became obscured, and did not reappear
for an interval of eleven minutes.

At 6h. 21m. 40s. the cloud cleared away, and I again saw the planet with
about half the disc on the Sun ; and, as there seemed some prospect of the
Sun remaining unobscured for some short time, I shifted the eye-piece to one
with a power of 120, and used a yellow dark glass.

The atmospheric disturbance round the limbs of the Sun and planet was
now rendered more apparent, and Venus appeared very much distorted.

At 6h. 24ra. 35s-2 I noticed for the first time that part of the disc of Venus
outside the Sun's limb. It appeared of a reddish brown colour, whilst that
part of her disc which had entered on the Sun's disc was intensely black

(Fig I.)-

About two minutes after, small semi-opaque clouds obscured the Sun from
time to time ; and at 6h. 28m. 44s, just about three minutes previous to the
time of internal contact by the N.A., the Sun became totally obscured.

Before the reappearance of the Sun, Lieut. Moore, who was noting the
times, informed me that the time of contact had passed.

At 6h. 33m. 0s. the Sun's disk could be just seen through some thin clouds,
obliging me to observe without a dark glass, and I fancied I saw the planet
still in connection with the limb of the Sun. Fortunately, just at this moment
(6h. 33™. 17Sl5) a break in the clouds revealed the Sun in all its brightness.
I had to withdraw my eye instantly, and put on a red dark glass, which, as
it happened, was of too light a shade ; but there was no time to exchange it
then, and I was very much surprised to see that Venus had not yet arrived
at her position of internal circular contact, the chord of cusps being a little
less than one-fourth of the diameter of the planet.

3E

396 TRANSIT OF VENUS, 1874. RODRIGUEZ. HERMITAGE ISLAND.

At 6h. 34m. 4s-8 I observed internal circular contact with as much precision
as the limbs of the Sun and Venus would admit of in such a state of
vibration.

Although I watched carefully, I noticed no alteration in the phenomena of
circular contact until 6h. 34m. 16s, when the planet's disk suddenly appeared
to be connected with the Sun's limb by a band of the same degree of
blackness as the planet, and about one-fourth of its diameter in width
(Fig. 2). I can speak with certainty of the decided and instantaneous
appearance of the phenomenon.

At 6h. 34m. 57s, the planet having advanced farther on the Sun's disc, the
ligament had increased in length to a small extent, rendering the phenomenon
of the connecting ligament still more striking than heretofore. At this most
critical time an interval of one minute and ten seconds seems to have ensued,
during which no change of phenomena took place. I pointed this out to
Lieut. Moore immediately after the observation of Ingress, and asked him if
he thought it possible that a mistake in the minute might have been made
in recording the times, but he was certain in his own mind that they were
recorded correctly ; and although the interval did not seem to me of such
a long duration, my attention being so absorbed in the phenomena then
occurring, my idea of the duration cannot have been otherwise than imperfect.
Therefore I can offer no explanation for this extraordinarily long interval,
during which occurred this absence of change of phenomena.

At 6h. 36m. 7S>9, in consequence of a slight diminution in the atmospheric
disturbance and in the breadth of the ligament, the ligament assumed a more
definite shape.

At 6h. 36m. 17S>4 the ligament appeared to be decreasing in width very
perceptibly, and at 6h. 36m. 32S>8 it had faded away, and light appeared all
round the planet's disc (Fig. 3). Nevertheless, the planet was very near to
the Sun's limb, and on watching very attentively I fancied at 6h. 36m. 438>2 I
saw the light interrupted by an extremely fine ligament which broke ; and
immediately after, light was again visible all round the disc of the planet.
This last phenomenon may possibly ha.ve been due to one of the waves of
vibration round Venus's limb interrupting the light, as the appearance and
disappearance were almost instantaneous.

At 6U. 41 m. the Sun became again obscured, and did not appear again for
an interval of a quarter of an hour.

On its reappearance most of the atmospheric disturbance had ceased, and
shortly after I was enabled to use the highest power in the telescope.

HOGGAN'S OBSERVATIONS OF THE TRANSIT. 397

The planet when on the Sun's disc appeared of a perfectly circular form,
and there was no appearance of refracted light round its edge, which was
very sharp, the whole body of the planet being intensely black.

In the original record of the observation of Ingress all the phenomena
attached to the times were registered instantly by Lieut. Moore, with the
exception of the important phenomenon of circular contact at 6h. 34m. 4Sl8,
and the less important phenomena attached to the times 61'. 33m. 36s-2 (re-
garding which time there is a correction on the left-hand side of the page
to 6h. 33m. 56s-2, to which Lieut. Moore's initials are appended), 6h. 36m. 73'9,
and 6h. 36m. 17S>4, which were written by myself, from memory, immediately
after.

The pocket chronometer Parkinson and Frodsham was used for recording
the times of the observation of Ingress. It was compared, both before and
after Ingress, with the other two chronometers, Hewitt and Cotterell.

Lieut. Moore devoted the interval between Ingress and Egress to obser-
vations of the altitude of the Sun, for the determination of local time.

Note by the Astronoiner Royal.

The remark made by Lieut. Hoggan, on the trifling character of the
change of phenomena between 6h. 34m. 57s. and 6h. 36m. 7S>9, throws a doubt
on the accuracy of the observation.

It seems possible that at 6h. 33m. 178'5, 6h. 34m. 4s-8, 6h. 34m. 16s, 6h. 34m. 57s,
10h. 3m. 18s-2, 10". 3m. 51s, 10". 3m. 56% and 10". 4m. 47s, the minute may have
been registered lm. too small ; while at 6". 36m. 7S>9, 6h. 36m. 17S>4, 6h. 36m. 32S>8,
and 6h. 36m. 43S>2, it was registered correctly.

These changes of several numbers appear to reconcile the observations at
Hermitage Island with other observations in Rodriguez.

Errors may sometimes be caused by noncoincidence of the minute-hand
with the minute-line when the second-hand points to 60. It was, however,
an Official Instruction to the Assistant who should read the clock or chrono-
meter, " It is desirable that he assure himself of the correspondence of
indications of the minute-hand and the second-hand."

Observation of Egress.

About twenty minutes before internal contact at Egress, the chronometers
being intercompared, I commenced observing the planet.

The observation of Egress was made under the most favourable circum-
stances. The Sun's limb and the planet's limb were both very sharply

398 TRANSIT OF VENUS, 1874. EODRIOUEZ. HERMITAGE ISLAND.

defined with the highest power (160) in the telescope. The dark glass used
was yellow. The first indication of approaching contact which I observed,
at 10h. 3™. 18s-2, was an elongation of the planet's limb in the direction of
that of the Sun. This did not appear to remain steady, but moved backwards
and forwards towards the Sun's limb without, however, entirely interrupting
the light (Fig. 1).

Up to the time indicated by 10h. 3m. 51s. the light was not entirely inter-
rupted, but at 10h. 3m. 56s. light was no longer visible between the limbs of
the Sun and Venus, being interrupted by a band of about one-eighth of the
diameter, and the same degree of blackness as the planet (Fig. 2). The
width of the band increased to about one-fourth of the planet's diameter up
to the time of circular contact, which phenomenon was observed at 10h. 4m. 47s.
(Fig. 3).

Having noticed the appearance of that portion of the planet's disc outside
the Sun's limb at Ingress, I now directed my particular attention to it again ;
and at 10h. 7m. I first perceived it emerging from the Sun's limb.

It appeared, as at Ingress, of a reddish brown colour.

Shortly afterwards I noticed that its outer limb became faintly illuminated
with a yellow light, presenting something of the appearance of a very young
moon with her horns directed towards the Sun's limb (Fig. 4).

The portion of the planet outside the Sun's limb retained the same
appearance in regard to colour and illumination of the outer limb up to
within a few moments of external contact, when the slow motion of the
telescope in zenith distance failed to act ; and before I could remedy this, and
bring the Sun into the field of the telescope once more, the planet had disap-
peared from off the Sun's disc, and, although I searched for her outside that
portion of the Sun's limb off which she had passed, I could discern nothing.

After the observation of Egress the chronometers were intercompared.

HOGGAN'S OBSERVATIONS OF THE TRANSIT.

399

For Lieut. Hoggan's observations we have, therefore, the following results,
assuming the Latitude 19°. 44'. 47" S., Longitude 4h. 13m. 46s. Bast of
Greenwich : —

Phenomenon observed.

Time
recorded by
Parkinson and
Frodsham
453°-

Local
Sidereal
Time.

Greenwich
Sidereal
Time.

Local Tabular
Distance of
Centers of Sun
and Venus.

Internal Contact at Ingress.

" Circular contact " -
or

" Ligament decreasing in width "
" It had faded away "

h in 3

6.33. 17-5
6. 34. 17-5

6. 36. 17-4
6.36.32-8

h m 8

1 1. 5o. 19*3
ii. 5i. 19*6

ii. 53. 19-7
ii. 53. 35-2

h m 8

7. 36. 33-2
7. 37. 33*4

7. 3g. 33-6
7.39.49-2

/ '/

I5.43-56
1 5. 41-64

i5. 37-82
1 5. 37-34

Internal Contact at Egress, the recorded times being increased
one minute.

" Light not entirely interrupted "

Light no longer visible between the
limbs.

10. 4. 5i-o
10. 4.66-0

l5. 22. 28-0

1 5. 22. 33-o

ii. 8.41-9
ii. 8. 46-9

i5. 41-38
i5. 41-54

The mean of the times recorded for " Ligament decreasing in width " and
" It had faded away " at Ingress gives the following equation for distance of
centers, taking E = 976"-80, r = 31"'42, and the mean solar parallax =

8"-950 (l + £) :-

+ 7"-8o = +o"-ig36 n +-6096 B R.A. —7504 8 N.P.D. — o"-o3o3 5 t — S R + 8 r.

Similarly, the mean of the two times for Internal Contact at Egress, taking
R = 976"'82, r and n as before, gives —

+ 3"'94 = -o"'027i n --2179 8 K.A. --9717 8 N.P.D. +o"-o332 fc t - 8 R + « r.

G. L. T.

3 F

TRANSIT OF VENUS, 1874.

PART IV.

EXPEDITION TO KERGUELEN ISLAND,

UNDEK

THE REVEREND S. J. PERRY, F.R.S.

SECTION I.

OBSERVATIONS AT OBSERVATORY BAY.
With One Plate.

SECTION II.

OBSERVATIONS AT SUPPLY BAY.
With One Plate.

SECTION III.
CHRONOMETRICAL CONNEXION OF STATIONS IN ROYAL SOUND.

SECTION IV.
OBSERVATIONS AT THUMB PEAK.

SF 2

TRANSIT OF VENUS, 1874.

PART IV.
EXPEDITION TO KERGUELEN ISLAND.

Section 1.
OBSERVATIONS AT OBSERVATORY BAY.

With One Plate.

404

INDEX.

Page
INTRODUCTION :

Voyage, and Names of Observers 405

Site at Observatory Bay 405

The Transit-Clock ...... . . 406

The Transit Instrument 406

Micrometer Screw and Intervals of Wires 407

Zero of Collimation 407

Level Error • 407

Error of Azimuth 408

Stars used for Clock-Error 408

Relative Personal Equations of the Observers 4O9

The Altazimuth Instrument 410

Runs of Micrometers of Vertical Circle of Altazimuth 411

Stars for Co-latitude 411

Refractions, Thermometers, Barometer, Adopted Latitude 412

Runs of Micrometer of the Horizontal Circle 413

Horizontal Intervals of the Vertical Wires 414

Corrections for Collimation 414

Error of Level of Horizontal Axis 415

References of Altazimuth Clock to Transit-Clock 415

Determination of Zero of Azimuth 415

Computation of Tabular Azimuth of the Moon on two assumptions of Longitude ... 416

Longitude of Observatory Bay from Meridional Observations of the Moon .... 417

Longitude from observed Azimuths of the Moon 418

Longitude from the Occultation of a Star by the Moon 418

Longitude derived from Professor Newcomb's determination of the Longitude of Molloy

Point 419

Longitude derived from Dr. Auwers' determination of the Longitude of Betsy Cove . . 421

Adopted Longitude of Observatory Bay 421

Observations of the Transit of Venus by the Rev. S. J. Perry 422

Observations of the Transit of Venus by the Rev. W. Sidgreaves 423

Equations thence deduced 425

OBSERVATIONS IN TABULAR ARRANGEMENT :

Table I. — Collimation of the Transit Instrument 428

Table II. — Error of level of the Transit Instrument 430

Table III. — Azimuth Errors 436

Tables IV. and V. — (Abstract) Transits of Stars and of the Moon, and Inferred R.A. of

the Moon's Limb at Transit 440

Table VI. — Longitude of Observatory Bay, from the Meridional Transits of the Moon . 443
Table VII. — Abstract of determinations of Longitude of Observatory Bay from observed

Azimuths of the Moon's Limbs 445

Plate XVI to face 405

Transit of Venus 181 4-, Keryuclen Island.

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405

VOYAGE, AND NAMES OF OBSERVERS.

THE Expedition for observation of the Transit of Venus at Kerguelen's
Land sailed from England in the Windsor Castle, a steamship of the " Donald
Currie Line," on 1874, June 20, and arrived at Cape Town on July 20.
Ample arrangements had been made by the Admiralty for carrying the party
with little delay to Kerguelen's Land ; but, from accidents to their own and
other ships, which rendered necessary a change of the vessels intended for
Kerguelen, the observers were delayed in Cape Town longer than had been
anticipated. Finally, however, H.M.S. Volage, Captain Fairfax, R.N., (with
the observers and some instruments) and H.M. storeship Supply, Staff-
Commander Inglis, E.N., (carrying instruments, &c.) sailed on September 18
and 17, and were in company from September 19 till they approached
Kerguelen, when they were separated by very heavy weather. Finally,
the Volage anchored in Island Harbour, Royal Sound, on October 8 ; and the
Supply joined her on October 11.

The Astronomical party consisted of the following gentlemen : —

Rev. S. J. Perry, F.R.S., Superintendent.

Lieutenant Coke, R.N.

Lieutenant Corbet, R.N.

Lieutenant Groodridge, R.N.

Rev. W. Sidgreaves.

W. Bagnall Smith.

THE SITE AT OBSERVATORY BAY, KERGUELEN ISLAND.

But little was known of Royal Sound, in the S.E. of Kerguelen Island,
until it was visited and explored by Captain (now Sir George) Nares, in
H.M.S. Ohalknger, in 1874. His Report and his partial survey of this region
reached England before the departure of the Transit of Venus Expedition,
and decided the matter as to the best place for the head-quarters of the
Expedition. In spite of very bad weather, Mr. Perry and Captain Fairfax,
accompanied by Commander Bayley, of the American sealing schooner Emma
Jane, visited many parts of the shores of the Sound, and ultimately selected

406 TRANSIT OF VENUS, 1874. KERGUELEN ISLAND. OBSERVATORY BAY.

a site on the southern side of the entrance of an inlet or bay, in the N.W.
corner of the Sound, in lat. 49°. 25/-2 S., long. 69°. 53' '5 E. This inlet
was named OBSERVATORY BAY, and is shown in the plan of Royal Sound
(Plate XVI.), as surveyed by Lieutenant VIVIAN, R.N., of H.M.S. Volage.

The wooden observatories and dwelling-house were erected on nearly level
ground, about 50 feet above the sea. Constant snow-storms and rains
interrupted the work of landing and erecting the huts and instruments ; the
land had to be drained, roads made, and a pier constructed ; but, with the
efficient assistance rendered by Captain Fairfax and the officers and men of
H.M.S. Volage, most of the work on shore was finished by October 26, when
the first observations were taken.

The Transit clock, by B. Dent and Co., of London, numbered 1915, was
similar to that used at Honolulu. Its tripod rested upon stakes driven
deeply into the ground through holes cut in the flooring of the observatory.

MERIDIONAL OBSERVATIONS.

The Transit instrument, its piers, the hanging level, and the wooden
observatory, were, in every respect, similar to those used at the other head
stations, and have been fully described in Part I., at page 9 et seq.

For the foundations of the transit pier, the subsoil was excavated until the
rock was reached. A bed of concrete was laid on the rock and levelled.
When this had set, a brick pier was built up to the level of the ground to
receive the great stone. The building of the piers was much impeded by
the rains ; and, although all possible care was taken with the foundations,
subsequent observations proved that the instrument was unstable at all times,
but especially after heavy rains. The instrument was fairly in the meridian
by November 3.

The value of one revolution of the eye-piece micrometer-screw (which
carried all five wires of the reticule) was found at different times, from
numerous observations of close circumpolar stars, the mean value being
56"'09. The integer revolutions were numbered in the observing books so
as to increase when the Avire was carried towards the screw head ; the center
wire coincided approximately with the optic axis when the reading was 20r-5.
The position of the transit-axis is always denoted by the record of the
micrometer-screw head being on the east or west side of the telescope.

TRANSIT INSTRUMENT. 407

The system of wires remained perfect during the series of observations,
and the equatorial intervals from the central wire, determined from 400 transits,
are : —

Wire I.

+ 427'4

II.
III.

+ zi4'4
o-o

IV.
V.

— 214-6
- 426-8

The order of the wires refers to the order in which stars above the pole
transit them with the micrometer west.

The center wire has always been considered to represent the mean of
wires.

The Zero of Collimation, or the reading of the micrometer when the center
wire coincided with the optic axis, was determined nearly every day by
observations of a distant mark with reversed positions of the transit axis.
The distant mark was some sharply-defined feature of the rock (different in
different observations) seen projected against the northern sky.

A Collimator, consisting of a telescope temporarily mounted on a tripod
stand, was also frequently used. All these observations, given in Table I.,
indicate that some of the screws at the eye end of the instrument were loose,
probably the ring clamp-screw.* The cause, however, was not discovered
during the course of observations ; and consequently, throughout the entire
series, the Zero of Collimation is subject to an uncertainty, corresponding to
about 3" of arc ; and it is probable that the relation between the center wire
and the optic axis was liable to be disturbed every time that the micrometer-
screw was touched. The adopted zero for each night is enclosed in a bracket,
thus [20-550].

The Level Error was found with the hanging spirit-level ; the value of the
graduations engraved on the glass bubble was tested by the makers before
the Expedition left England, when it was found that 41 divisions were
equivalent to one minute of arc, which value has been used throughout.
(Table II.)

Determinations of the wiequality of the pivots were made in 1873, November,
1874, November, and 1875, January. On all three occasions it was found

* The ring-clamps of the Honolulu and New Zealand instruments worked loose during the
outward voyages, and caused similar trouble at first.

3 o

408 TRANSIT OF VENUS, 1874. KERQUELEN ISLAND. OBSERVATORY BAY.

that the correction to the level-error with the micrometer west was — 0"P80,
and this value has been applied throughout.

The Error of Azimuth (Table III.) has been found in the usual way by
combining the observed transits of two stars of suitable declinations cor-
rected for level and collimation. Occasionally, the observations of the north
mark have been used to determine the azimuth-error ; but such was the
instability of the instrumental mounting, that it is never safe to deduce the
clock-error, unless a circumpolar star was observed at the same time as
the clock stars. For this reason several transits of the Moon cannot be
utilised. No stars were observed near the zenith; the rate of the clock,
however, appears to have been exceptionally steady.

The transits (abstracted in Table IY.) have been reduced in the manner
described in the Introduction to the Honolulu Observations. Imperfect
transits have been reduced to the center wire by means of the equatorial
intervals given above.

The stars observed for clock-error were taken from the Nautical Almanac
for 1874 or 1875. The Mean Right Ascensions are taken from the Greenwich
Catalogue of 2760 Stars for the Epoch 1864, the reductions from mean to
apparent place being taken from the Nautical Almanac.

For the determination of azimuth-error, Mr. Stone's Catalogues of
8 and 78 Southern Circumpolar Stars were used. The mean places for 1874,
January 1, have been given in Part III., page 356.

The true clock time of transit of the Moon's limb in the eighth column
requires a further correction of — Os<02 for diurnal aberration.

The transits of stars selected for publication are those observed in con-
nection (1°) with every observation of the Moon for absolute longitude;
(2°) with chronometric differences of longitude ; (3°) with the actual Transit
of Venus.

The abstract of Table V. contains the Errors and Rates of the Transit
Clock, the errors being corrected for the approximate values of the personal
equations, assuming Mr. Sidgreaves (WS) as the standard. The clock's
loss in 24 hours corresponds to the middle time between the two sets of
observations from which it has been deduced ; the adopted rate corresponds
to the approximate sidereal time given. When the interval of time for
which clock-rate has to be allowed in determining the sidereal time for any
purpose exceeds six hours, the " loss in 24 hours " has been used as the rate.

For reasons before mentioned, the clock-error cannot be considered certain

MERIDIAN TRANSITS, AND PERSONAL EQUATIONS.

409

when there has been an interval of several hours between the observations of
the clock and circumpolar stars. The second place of decimals in the value
of " Clock Slow " will generally have no significance.

The observers are indicated, where required, by the initials —

P

C -
CO
G -

ws

BS

Mr. Perry.
Lieutenant Coke.
Lieutenant Corbet.
Lieutenant Goodridge.
Mr. Sidgreaves.
Mr. Smith.

EELATIVE PERSONAL EQUATIONS OF THE OBSERVERS.

Although there are not many observations of transits of stars by two
observers on the same night, the steadiness of the clock-rate admits of
approximate values of the relative personal equations being obtained by
comparing one day with the next.. Nearly the whole of .the azimuths of the
Moon were observed by Mr. Sidgreaves, with local time obtained by another
observer with the transit instrument. Mr. Sidgreaves' custom of observing
the azimuth of a star with every observation of azimuth of the Moon
practically makes the latter independent of small errors in the local time ;
but as the habits of these observers appear to differ in a very unusual
manner, the approximate differences have been investigated. In the following
table the equation P — G = + Os>06 signifies that P makes the clock O06
more slow than does G. Every one of these determinations is affected by
the uncertainty of the collimation zero, and nearly every one of them by
uncertainty of the azimuth error. The second place of decimals must, of
course, be regarded as of no significance.

Interval

Interval

Day.

of Time
between
the Obser-

Observers and Excess cf
"Clock Slow."

Day.

of Time
between
the Obser-

Observers and Excess of
"Clock Slow."

vations,

vations.

1874.

h

|

1874.

h

•

Nov. 6

4

P _ G = +0-06

Nov. 17

24

P — BS = + 0-20

7

3

P - G = + -49

18

4

BS- G = — -08

12

'i

P - G = - -2i

18

24

BS— P = + -io

i5

i

WS-BS = + -56

18

24

G - P = + -20

16

2

WS — BS = + 0-20

'9

I

WS- P = +0-29

3 G 2

410 TRANSIT OF VENUS, 1874. KERGUELEN ISLAND. OBSERVATORY BAY.

Interval

Interval

Day.

of Time
between
the Obser-

Observers and Excess of
" Clock Slow."

Day.

of Time
between
the Obser-

Observers and Excess of
« Clock Slow."

vations.

vations.

1874-5.

b

8

1874-5.

h

3

Nov. 19

4

P - G = -o-3g

Jan. 1 1

24

C -CC = + 0-20

20

24

G — P = + -3o

12

24

CC — P = + -40

22

2

WS— P = + '27

25

18

CC - C = + -3o

Dec. 1 1

24

P -BS = + -25

27

3o

C - P = + -io

i5

4

WS- G = + -23

Feb. 2

24

S -CC = + -32

'7

»*

WS— B = + -47

7

24

C - P = + -42

18

2

WS- G = + -32

12

24

CC - P = + -20

23

24

P - G = + -20

12

24

C - P = + '65

27

3

WS- P = + -63

18

24

CC - P = + '63

Jan. 3

24

C - G = + -12

19

24

C - P = + '3o

10

24

C -CC = + -35

20

24

C - P = + -40

10

24

CC - P = +o-45

21

20

CC - C = +0-25

Adopting "W S as the standard, the following values result : —

P

=

+ 0-29

C

=

— O'lO

CC

=

— O'lO

G

=

4- o'25

WS

=

O'OO

BS

=

+ °'44

which have been applied to the " Clock Slow " determined by observation, as
given in Table V.

THE ALTAZIMUTH OBSERVATIONS.

The Altazimuth used at Observatory Bay was constructed expressly by
Messrs. Troughton and Simms, and is a model of stability and good work-
manship. It was intended to measure both azimuths and zenith distances.
The rotating body of the instrument, including everything necessary for the
measurement of zenith distances, is similar to the vertical circles used at
Honolulu and Rodriguez (already fully described), with the addition of the
four microscopes for reading the fixed horizontal circle, the arms supporting
these being cast in one with the rotating body. The reticule contained five
vertical and five horizontal wires of spider's web. The observed zenith
distances being of stars for latitude, only the central horizontal wire was
used. The upper zenith-distance level was graduated with 72 divisions, and

ALTAZIMUTH VERTICAL CIRCLE, RUNS OF MICROMETERS.

411

the lower with 60 divisions, to one minute of arc. The " Level Indication "
is one-fourth of the sum of the four readings, diminished by one-twentieth
of the sum of the readings of the upper level. Strictly, the diminution
should have been one-twenty-fourth of the sum for the upper level ; but the
error has no appreciable effect upon the final latitude, the vertical axis being
always within a few seconds of true perpendicularity. The level zero is
included in the zenith point. The vertical circles are 14 inches in diameter,
divided to 5' spaces. Both pivots are pierced, to enable the instrument to be
used with both positions of the horizontal axis in regard to its supports,
but this entails the reversal of the levels and micrometers to make the
direction of graduation accord with that on the circles.

The correction applied to the reading of the vertical circle for runs of the
micrometers is shown in the following table : —

CORRECTION for RUNS of the MICROMETERS of the VERTICAL CIRCLE.

Day.

Correction for Runs for 100".

Day.

Correction for Hans for 100".

Observed.

Adopted.

Observed.

Adopted.

1 874-5.

„

"

1875.

"

tt

Nov. 22
24
24

+ i'3o
+ 0-90
+ o-g3

J

Jan. 27
28
Feb. 3

+ 0'2O

1 + o'5o

26
26
27

27

+ 0-08
- o-53

+ I '20
+ 0'80

i — 0'22
> + I -00

3
5

7
8

+ 0-68

— Q- IO

I + o-3o

Dec. 3

27

1 + o-65

8

12

+ 0'32

+ o-55

}+ 0-09

3i

+ o''45

}l D * %n

12

— 0-42

3i

+ o'i5

^^ \J *J\J

13

...

+ 0-46

Jan. 3
3

+ i'65
+ i-63

j+i-64

'4
'4

+ 0-88
+ o-83

j + o-85

5
5

+ 0-43
+ o-65

1 + 0-54

»7
'7

- 0-27
— o-33

> — o'3o

i3

+ 1-28

"j

18

• . .

O'OO

i3

25

+ 1-35
+ 1-18

I + .'.5

21
21

+ 0-62
+ 0-73

| + 0-68

25

+ 0-80

-1

The stars selected for the determination of co-latitude were such as had
been well observed in N.P.D. at Greenwich, Melbourne, or the Cape of Good
Hope. For stars South of the equator the N.P. Distances of the southern

412 TRANSIT OF VENUS, 1874. KERGUELEN ISLAND. OBSERVATORY BAT.

observatories have been used. The reductions from mean to apparent places
have been taken from the Nautical Almanac for all stars found in that work.

The refractions have been computed by the tables forming the Appendix
to the Greenwich Observations for 1853, and then reduced in the proportion
of 1 to 0-9947. "Whether this reduction was proper or not is of little
importance, as stars were observed North and South of the zenith.

An aneroid barometer, suspended in the Altazimuth observatory, was read
in connection with the zenith distance observations ; in addition to which a
mercurial barometer, Adie M 33, properly tested before leaving England,
was suspended in the observer's dwelling-house, and read every four hours.
These readings generally afford the means of ascertaining the error of the
aneroid with sufficient accuracy, as shown by the following table : —

Number Correction

Month. of to

Comparisons. Aneroid.

in-

1874, April 8 —0-29

,, November 14 —0*34

, , December 4 — o'3i

1876, January 9 —0-29

, , February 1 6 — o • 32

The correction — Oia>32 has been applied throughout.

From the observations (of which it is unnecessary to print the details) we
have the following result for the co-latitude of the Altazimuth pier at
Observatory Bay : —

O I II

By 26 stars North of zenith, co-latitude is 40. 34. 48'2 S.
, , 8 , , South , , , , 40. 34. 48'0 S.

Adopted latitude... 49°. 25'. 11"'9 S.

OBSERVATIONS OF AZIMUTH.

The horizontal circle, 15 inches in diameter, fixed upon the tripod stand,
is divided into spaces of 5', and is read by the four microscope-micrometers
attached to the revolving body. It was intended that a revolution of the
screw of each micrometer should be one minute, and the screw-heads were
divided on silver into 60 parts or seconds. The stationary portion of the

ALTAZIMUTH HORIZONTAL CIRCLE, RUNS OF MICROMETERS.

413

body of the instrument, consisting of the vertical axis, the horizontal circle,
and the tripod stand, was undisturbed during the series of observations,
except by occasional adjustments of the foot screws, each of which rested in
a radial groove cut on the surface of a brass plate, which was countersunk
in the circular slab of slate that was cemented to and formed the top of the
pier. The delicacy of the levels used with the instrument made it imperative
to preserve the vertical axis within a few seconds of true perpendicularity.
The pier seems to have undergone but little or no settlement.

The runs of the micrometers of the horizontal circle were observed as
follows, chiefly by Mr. Sidgreaves : —

CORRECTION for RUNS of the MICROMETERS of the HORIZONTAL CIRCLE.

Date.

Correction for Euns for 100".

Date.

Correction for Euns for 100".

Observed.

Adopted.

Observed.

Adopted.

1874-5.

//

it

1875.

»

"

Nov. 1 5

+ 0-68

"|

Jan. 1 3

+ o'g5

i5

17

+ 0'53

i3

22

+ o-58
+ 1-17

> + 0-81

«7

— o'45

22

+ O'52

|

18

+ 0-78

23

+ o'5o

18

— o'5o

23

O'OO

IQ

— O'O2

26

+ O' 12

19
22

4- o'o5
+ i 'o5

>• + 0-19

26

27

-f o'i5

+ 0-72

> + 0-23

8

— 0-28

— 0*27

27
29

— o-o5
+ o-53

26

+ O'2O

29

— o* i5

3o

+ °'47

Feb. 8

— O'22

3o

— o- 15

8

— 0-48

Dec. 1 7

— 0'2O

<

ii

— o'o5

>• — 0*24

»7

+ o-o5

ii

— 0'22

24

+ O'OJ

12

+ o-3o

24

+ O'O2

12

+ o- 15

28
Jan. 8

+ 0-17
+ 0-45

> + O'll

'4
«4

+ 0-18

+ O'22

>• + 0-24

8
10

— O'O2

+ o-38

21
21

+ o-6o
— o-o3

j

10

+ O'lO

1

The horizontal intervals of the vertical wires were determined by
Mr. Sidgreaves as follows :—

414 TRANSIT OP VENUS, 1874. KERGUELEN ISLAND. OBSERVATORY BAY.

1874, 1875.

Number of
Determina-
tions.

Distance from the Center Wire.

Wire I.

Wire II.

Wire IV.

Wire V.

Nov. 1 5 to 1
Dec. 3 - /

«4

/ //
+ y-^-g

/ //
+ 3.56-4

/ //

- 3.47-2

/ ft
- 8. 2'8

Dec. 27 to"!
Jan. i - J

10

+ 7-44-9

+ 3.48-0

- 3.49-9

- 8.4-4

Jan. 1 3 to 1
Feb. 13 - /

10

+ 7-46-5

+ 3.48-1

— 3.48-3

- 8.3-5

A new set of wires was inserted on December 23.

The intervals of the wires from the mean wire employed in the reduction
of imperfect transits are : —

From Nov. 15
to Dec. 22.

From Dec. 23
to end.

Wire I + 7. 41 'o

,, II + 3. 5g-5

,, III +o. 3-i

,, IV -3.44-1

,, V -7.59-7

+ 7-49'6
-f- 3. 52'o
+ o. 3-9
-3.45-2
— 8. o-o

"When the wires were brought in succession, in the order above given, upon
the distant azimuth mark, the lamp being to the observer's right hand, the
circle-reading increased. In the same position of the instrument, the Moon
passed the wires in the same order.

The Correction for Collimation is referred, for convenience, to the mean of
the wires. It has been deduced from all the observations of stars on the
five wires, as well as from those of the distant mark by the center wire only,
the results being given in Table I. No explanation can be given of the
systematic difference in the collimation corrections obtained by the two
methods,* nor of the sudden change on November 27. On that day
carpenters were employed in the hut for some alterations.

The Error of Level of the horizontal axis was determined with a striding

* The intervals of the wires from the center wire were determined with such accuracy that
some other reason for the discordance must exist.

ALTAZIMUTH WIRES, COLLIMATION, LEVEL ERROR, AZIMUTH ZERO. 415

spirit-level at every observation of azimuth. The value of the graduations
engraved on the glass bubble, determined by the makers, was 60 to one
minute of arc. The Error of Level is corrected for the inequality of the
pivots of the horizontal axis. This inequality was determined by Mr. Sid-
greaves, by reversing the axis eight times on 1875, January 2, to be 0"'52,
and by an equal number of reversions on January 5, 0"'48, the smaller pivot
being on the same side as the lamp. The correction applied to the level-
error on this account is 0"'50, positive with lamp left, negative with lamp
right.

Mr. Sidgreaves, by a number of suitable levellings, determined that the
pillar supporting the axis on the lamp side was shorter than the pillar on
the side of the micrometers by O00030 of an inch, causing a constant
difference in the level-error lamp R. and lamp L. of 12"%6, a circumstance
which caused much trouble when observing with the instrument. After
leaving the makers' hands it had been carelessly taken to pieces.

Nearly the whole of the observations of the Moon in azimuth, for the
determination of the longitude of the station, were made by Mr. Sidgreaves,
who, whenever possible, made one or more observations of stars with large
zenith distances. The local sidereal time determined by one observer with
the transit instrument was transferred to the Altazimuth-clock, and used
generally for the azimuth observations by another observer ; but the adoption
of a zero of azimuth determined by a star at the same time and with the
same clock-error practically eliminates a systematic error that might thus
arise, and the observations become strictly differential.

The azimuth observations of the Moon should be divided into two classes —
those accompanied by a star, and those without. The former present no
difficulty ; the zero of azimuth derived from the star (or stars) by an observer
is applied to his observations of the Moon, thus eliminating systematic error.
In the treatment of the latter class, which cannot be made perfectly satis-
factory, the observations of the distant azimuth-mark have been taken as
affording the best zero of azimuth obtainable ; the absolute azimuth of
the mark being taken as 235°. 41'. 8"'7, which is the mean of 23 deter-
minations. The distant mark was a sharply-defined edge of rock
projected against the sky. It was always observed by Mr. Sidgreaves
himself.

The horizontal transits of the Moon and stars were taken over the middle

3 H

416 TRANSIT OF VENUS, 1874. KERGUELEN ISLAND.

portion of each, wire, the zenith distance slow-motion-screw being turned as
requisite, and the times being recorded by the Altazimuth-clock. The
microscopes of the horizontal circle were then read, and the striding level
applied. The Altazimuth-clock was made by E. Dent, of London ; the
pendulum-rod was of wood. The clock was compared with the Transit-clock
by the intervention of a solar half-seconds chronometer at instants when
the beats coincided.

For imperfect transits over the five vertical wires a correction has been
applied to the circle-reading, equal to the distance of the mean of the wires
observed from the mean of the five, multiplied by the cosecant of the
apparent zenith distance ; and the same factor corrects the collimation.
The correction to the circle-reading for level-error is the level-error
multiplied by the cotangent of the zenith distance.

The Greenwich mean solar time, corresponding to the local sidereal
time of each, observation (obtained by applying the Altazimuth-clock
correction to the clock-time of transit) has been computed on the two
assumptions of east longitude 4h. 39m. Os>0 and 4h. 49m. O'O. For each of
these Greenwich mean times the Moon's Geocentric Eight Ascension, North
Polar Distance, Equatorial Horizontal Parallax, and Semidiameter, have been
interpolated with second differences from the hourly ephemeris in the
Nautical Altnatiac.

The tabular azimuth of the Moon's limb has then been computed in the
following manner : —

The logarithm of the distance from the center of the earth to the point
where the normal of Observatory Bay intersects the axis of the earth, called
the axial distance of the normal-center, has been taken as 7'7046.

The correction to be applied to the Geocentric S.P.D. to obtain the
Normal- centric S.P.D. has been computed from the formula —

Correction (always negative) = seconds of equatorial horizontal

parallax

X sine Geocentric S.P.D. of center
X axial distance of normal center.

The tabular azimuth of the limb, and the tabular zenith distance, are thus
computed : —

If a great circle passing through the center of the Moon intersect the
meridian at right angles, and the arc of the meridian between the points of

LONGITUDE OF OBSERVATORY BAY. 417

intersection and the Pole be called 0, then, y being the astronomical co-
latitude, —

tan 0 = cos hour-angle X tan Normal-centric S.P.D.,

., 0 tan hour-angle x sin B

tan azimuth of center = - 8in (fl — ) - »
cot zen. dist. of center = cot (3 — 7) . cos azimuth.

The approximate apparent zenith distance, column 7, has been obtained by
adding, to the Z.D. thus found, the approximate parallax in Z.D. taken from
Table 39 of Raper's Navigation.

The azimuths are reckoned from South through West to 360°.

The azimuthal semidiameter, to be applied to the above azimuth of the
center to obtain that of the limb, is found by multiplying the geocentric
semidiameter (in seconds of arc) by the cosecant of the tabular normal-
centric zenith distance of the center. The small correction required to
reduce the geocentric semidiameter to the normal-centric diameter has
generally been taken into account, although its greatest value is 0"'l.

If «j, a.2 be the two tabular azimuths of the limb, corresponding to the first
and second assumptions of longitude respectively, and a0 be the observed
azimuth, the longitude inferred from each observation is —

6°9X fo-"")

4h. 39m. 0-0

al —

The details of the extensive calculations are suppressed, for the same
reason which applied to those of the Altazimuth Zenith Distances at
Rodriguez.

ON THE LONGITUDE OF OBSERVATORY BAY.

(1.) Longitude of Observatory Bay from the observed Bight Ascension of the

Moon on the Meridian.

In Table IV. are given the transits of the Moon as observed. The
incomplete transits have been reduced as described in Part I., page 22. In
Table VI. the longitude is computed from each observation, except a few
when the clock and instrumental errors cannot be inferred with safety. The
weights assigned are proportional to the square of the change of R.A. in 1s,
reduced in certain cases.

3 H 2

418 TRANSIT OF VENUS, 1874. KERGUELEN ISLAND.
The longitude of the transit pier is obtained as follows : —

Observer. J I. Number of Obs. 3> II. Number of Obs. Mean. Final Weight.

s a h m a

Coke 37425 3 30-97 3 4.39.34-1 I

Corbet 46-06 2 23- 11 2 4.39.34-6 i

Perry 32-76 3 24-8 I 4.39.28-8 |

Sidgreaves . . o 28-5 i ...

Goodridge . . o 34 '65 2 ...

Smith 25 "i i o

Mean 4. 3g. 33 • 2

It will be remarked that three of the observers have observed only one
limb of the Moon. The case of Corbet shows how unsafe it would be to
give any weight to observations of one limb only. Hence the final longitude
by this method is made to depend upon three observers only.

(2.) Longitude of Observatory Bay from the observed Azimuths of the Moon.

These observations must be divided into two classes — those when a star
has been observed with the Moon, Class A., and those when no star was
observed, Class B. When the extreme instability of the transit instrument
in collimation and azimuth is considered, but little weight can be given to
the observations of Class B. The longitude by Altazimuth therefore depends
entirely upon Mr. Sidgreaves, for he alone observed both limbs of the
Moon.

Thus we have, Class A., observer W S —

h m s

By J) I., 1 8 sets of observations, longitude .... 4. 3g. 35' 26
By 5 II., 10 „ „ 4.39.32-54

Mean 4. 3g. 33 • 9 East of Greenwich.

(3.) Longitude of Observatory Bay from the observed Occultation of 9 Tauri
by the Moon, 1874, December 20.

The observation was made by W S with the 6-inch Equatorial.
The star disappeared at the Moon's dark limb, at 5h. llm. Os>5 by the
Equatorial-clock.

LONGITUDE OF OBSERVATORY BAY. 419

The following comparisons were then made : —

h m a h m s

Chronometer Frodsham 3i;8 .... 1 1. 21. 40-5 "1 1 1. 36. 5o-o 1

"Rnna.torml-p.lopk . 5. 17. 23'oJ 5. 32. 35'oJ

Equatorial-clock 5. 17. 23 'o .

Chronometer Frodsham 3178 .... 11.26. i5-5l 11.29. i5'

Transit-clock 5. 22. 41-0 / 5.25.41'

With the Error and Rate of the Transit-clock in Table V., the Equatorial-
clock is inferred to be lm. 12S'76 slow on local sidereal time. Hence we
have : —

Local sidereal time of disappearance 5h. I2m. i3"*26

Assumed corrections —

to the Moon's Tabular Geocentric R.A — os%55

N.P.D -."-7

to the horizontal parallax for latitude —6"' 96

to the semidiameter (Breen's correction) — 2"-oo

Augmentation of the semidiameter +4" 'So

For the mean place of 9 Tauri for 1874'0 —

Greenwich Catalogue for 1864 —

R.A. 3h. 29™. 33s -5g (4 obs.) N.P.D. 67°. 12'. 2 7" -4 (4 obs.)
Greenwich Catalogue for 1872 —

R.A. 3h. 29™. 33"-57 (3 obs.) N.P.D. 67°. 12'. 27"'o (2 obs.)
Reduction to apparent place, 1 s — 2 1 " ' 3

1874, December 20 /

Adopted apparent place of 9 Tauri —

R.A. 3h. 29™. 37s -58 N.P.D. 67°. 12'. 5" -9.
Assumed astronomical co-latitude 40°. 34'. 48" ' i S.

h m s h m a

Assumed East longitudes 4.39.24-00 4.39.44-00

Greenwich Mean Times, December 20 6.36. 7 '83 6.35.47*88

Apparent R.A. of Moon's center 3. 28. 46*06 3. 28. 45*21

O I II O I II

,, N.P.D. ,, 67.23.24-9 67.23.28*8

in t It

Distance of star from Moon's center 1 6. 24 • 53 1 6. 35 * 73

Moon's augmented semidiameter 16. 3i'ii 16. 3fii

Inferred longitude East of Greenwich... 4". 39m. 358*8.

The occultation of 9 Tauri was also observed at the American Station
at Molloy Point. Professor S. Newcomb kindly communicates that the
longitude of Molloy Point inferred from the occultation is —

4h. 40m. 2P-7 East of Greenwich.

420 TRANSIT OF VENUS, 1874. KERGUELEN ISLAND.

For the difference of longitude between Molloy Point and Observatory Bay
we have the following : —

Molloy Point,

East of
Observatory Bay.

in 8

By chronometers in the Gazelle o. 47 • 4 (Auwers).

By chronometers in the Volagc o. 46 • 9 ->

Again by chronometers in the Volage . o. 46 • 3 > See next section.

By rocket signals o. 47 • 2 J

Mean o. 46 • g5

The same occultation was also observed at the German Station at Betsy
Cove, Kerguelen's Island. Professor A. Auwers kindly communicates the
following, by letter dated 1879, October 18 : —

" From the occultation of 9 Tauri, 1874, December 20 (good observations,
two observers) —

" Longitude of Betsy Cove, East of Greenwich, 4h. 40m. 43St2 ;
with mean error, ± 2s-6.

" I have computed this occultation with Newcomb's corrections to
Hansen's Tables, modified so as to agree with the Luxor occultations.* The
mean error has been found, supposing the mean error of each relative
co-ordinate to be ± 1"'5."

The last occultations observed at Luxor were on 1874, December 15, only
five days before the Kerguelen occultation; and, the longitude of Luxor
having been obtained by telegraphic signals with Mokattam, it may be
supposed that Dr. Auwers' reduction of the occultations is the most free
from systematic errors.

The difference of longitude between Betsy Cove and Observatory Bay was
found as follows : —

Betsy Cove,

East of
Observatory Bay.

By chronometers in the Gazelle

m
1

8
1 1

•^

(Auwers)

By chronometers in the Volaoe . . . .

1

] I

' Ol

Again by chronometers in the Volagc

I.

10

•72

(Corbet).

Adopted

1

I I

' 1Q

(Auwers)

-•»•

* Beobachtung des Venus-Durchgangs von 8 December 1874, in Luxor, von A. Auwers.
Berlin, 1878, page 122.

LONGITUDE OF OBSERVATORY BAY, FINAL RESULT. 421

"We have, therefore, the three following determinations of the longitude
of Observatory Bay, as inferred from the occultation of 9 Tauri : —

h m s

From the Betsy Cove observation ........ 4. 3g. 32 -o

Molloy Point ,, ........ 4. 39.64 '76

Observatory Bay observation ... 4. 3g. 35' 8

,,
, ,

Mean, giving double weight to ]

> 4. 3o. 33 '
the Betsy Cove result ..... J

The circumstances of the occultation were very favourable, as the center
of the Moon passed within 6' of the star.

(4.) Longitude of Observatory Bay from the Lunar Observations at Betsy Gove.

Communicated by Dr. Auwers.

Mean. Betsy Cove,
Observer. Instrument. J) I. 3> II. West of Greenwich.

3 s h m s

Weinere
Borgen

Transit
Altaz.

45-56
48-45

2 I '5 43'4I

16-8 43-38

23-6
6-7

4.40.45-92

Adopted . .

4.. 4.O. 4.4. " Q I

T T- TT J

Applying the difference of longitude as before, we have for the longitude
of Observatory Bay from these observations —

4h. 3gm. 33" 72.

The corrections applied to the Moon's Tabular Right Ascension were the
same as those used in reducing the transit-observations at Observatory Bay.

We have, therefore, the following results for the longitude of the transit
instrument at Observatory Bay : —

h m a

By the Meridional transits at Observatory Bay (3 observers) ... 4. 3g. 33 • 2 E.
,, Altazimuth observations ,, (i observer j ... 4.39.33-9

, , Occultation of 9 Tauri , , (4. observers) ... 4. 3g. 33 • 6

, , Meridional and Altazimuth observations at Betsy Cove "|

. > 4. 3g. 33 "j
(2 observers) . . . J

Adopted 4. 3g. 33*5

It seems highly improbable that the error of this determination can
exceed 2s.

G. L. T.

422 TRANSIT OF VENUS, 1874. KERGUELEN ISLAND. OBSERVATORY BAY.

OBSERVATIONS of the TRANSIT of VENUS, 1874, December 8, by the
Reverend S. J. PERRY, with the 6-inch Equatorial.

The double-image micrometer, with power slightly over 150, with an
achromatised wedge of dark glass — and the negative eye-piece, power 150,
with two dark glasses — were conveniently placed ; and two other wedges of
neutral-tint glass — -one very light, the other dark — were at hand in case of
need.

The driving-clock of the Equatorial being very inferior, and having no
efficient regulating gear, it was necessary to add a new driving power to
assist the clock, and to fit a regulating rope to the new driving weight.
This was done very effectively by the Rev. W. Sidgreaves.

Lieutenant Gamble, R.N., arrived from H.M.S. Volage at 6 a.m., and we
at once examined the time required for altering eye-pieces, focussing, &c. ;
this was about 30s.

The morn had been very fine, but the clouds were thickening fast.
Unfortunately a dense cloud settled just over the Sun for about 20 minutes,
and there was scarcely a breath of wind to move it.

It was impossible to use the double-image micrometer until Venus was
well on the disk, and even then the images were faint without any dark
glass.* The wind was rising, and this, combined with the faintness of the
light through the clouds, rendered the use of the micrometer at Egress quite
out of question.

The times given below are those given by Dent 2011 uncorrected : —

12h. Om. 56S>5. Venus half on the disk ; solar prism and negative eye-
piece, power 150.

15h. 40m. 38s-8. A good geometrical contact ; solar prism, power 150 ;
no dark glass. There was no appearance of black
drop before contact, but this might have been due
to the obscuring clouds.

* The few micrometer readings obtained cannot be utilized.

PERRY'S AND SIDGREAVES' OBSERVATIONS OF THE TRANSIT.

423

I tried the micrometer again for the measurement of cusps, but the light
was too faint.

15h. 56m. 3s. Venus half off the disk. Solar prism, power 150 ; the
light end of the neutral-glass wedge used. The limb
of the Sun was very well denned, and the limb of
Venus did not appear to be irregular.

16h. 11™. 25S>8. External contact; solar prism, power 150. Possibly
a little too early.

S. J. PERRY.

COMPARISONS of the CLOCK Dent 2011 with the TRANSIT-CLOCK, by the
intervention of the MEAN SOLAR HALF-SECONDS CHRONOMETER Frodsham
3178 ; 1874, December 8.

Time by Transit-
Clock at Com-
parison with
Chronometer.

Time by Frodsham 3178.

Time by Dent 2011
at Comparison
with Chronometer.

Inferred Dent 201 1
Slow on Local
Sidereal Time.

At Comparison
with Transit-Clock.

At Comparison
with Dent 201 1.

h m s

9. 5i. 5ro
10. 10. 3o'o
16. 3o. 3o-o
16. 43. 10-0

h m s

4.42. 4'5

5. o. 40-5
n. 19. 3g-o
1 1. 32. iyo

h m s
4. 5l. 67-0
5. 4. 3-o

I I. 23. IO'O

11.35. 48-0

h m 9
10. I. 27-0

10. i3. 35"o
1 6. 33. 44-0
16. 46. 24-0

in s
+ I. 10-94

I. 10-91
i. 11-28
+ i . 1 1-34

OBSERVATIONS of the TRANSIT of VENUS, 1874, December 8, by the

Reverend W. SIDGREAVES.

The instrument used by Mr. W. Sidgreaves was achromatic, of 4 inches
aperture, kindly lent by the Royal Astronomical Society. It was equatorially
mounted upon a tripod stand ; slow motion in R.A. was effected by a handle
and Hook's joint. It was fitted with a solar diagonal reflecting prism.

Time was recorded by Lieutenant T. G. FENN, of H.M.S. Volage, from the
Solar Chronometer Appleton 195.

Nothing was seen of the Ingress.

3 i

424 TRANSIT OF VENUS, 1874. KERGUELEN ISLAND. OBSERVATORY BAY.

Egress.

Time by
Appleton 195.

h in 3

22. 27. 42'8. Geometrical contact. Scarcely visible through, cloud. Very
uncertain judgment. Bye-piece, power 150 used ; with-
out a coloured glass.

22. 43. 42'5. A guess at the time of transit of the center of the planet
over the Sun's limb. Image faint, but brighter than
before. Without a coloured glass.

22. 58. 19'2. External contact. Without a coloured glass. Image bright,
through haze. I think I got it fairly exact.

W. SlDGREAVES.

COMPARISONS of the CHRONOMETER Appleton 195 with the TRANSIT-CLOCK
at OBSERVATORY BAY, 1874, December 8.

Time by Transit-
Clock.

Transit-Clock
Slow.

Time by Appleton
'95-

Appleton 195
Slow on Local Mean
Solar Time.

Hourly Losing
Rate.

h m s

s

h m

m s

s

9. 53. 43*0

10. 7.35'0

16. 25. 29-0
16. 38. 9-0

+ 52-82

52-85
53-68
+ 5371

16. 41. 45*0
1 6. 55. 35-o

23. 12. 25'5
23.25. 3-2*

+ 2.34-I2
+ 2. 33'87

+ 2.36-28
+ 2.36-24

+ o-36

* Assumed to be 23*. 25™. 3* -5.

For Mr. Perry's observations of Egress we have the following results,
assuming the Latitude 49°. 25'. ll"-9 S., Longitude 4h. 39m. 338'5 East of
Greenwich : —

Phenomenon observed.

Recorded
Time by De.nt

201 I.

Dent 30i i
Slow.

Local Sidereal
Time.

Greenwich
Sidereal Time.

Local Tabular
Distance of
Centers of Sun
and Venus.

EGKESS.

h m s

m s

h m s

h m s

/ (/

Internal " Geome- 1
trical " Contact - /

15.40. 38-8

+ I . I I -3

1 5. 41. 5o'I

ii. 2. 16-6

i5. 41-72

External Contact 1
" probably early " /

16. 11. 25-8

+ i. u-3

16. 12. 37-1

n.33. 3-6

16.45-80

EQUATIONS DERIVED FROM THE TRANSIT,

425

Taking R = 976"-82, r — 31"'42, and mean solar parallax =
8"-950 X (l + T^J, we have the equations—

For Internal " Geometrical " Contact —

+ 3"-68 = +o"-ioo4 n — -1969 8 R.A. —'9772 8 N.P.D. + o"-o3og 8< — SR + 8r,

and for External Contact —

+ 2"- 44 = + o"-og53 « —'2983 8 R.A. —-9463 8 N.P.D. + o"-o376 8< — 8R — 8r.
For Mr. Sidgreaves' observations are obtained the following results : —

Phenomenon observed.

Recorded Time
by Appleton
'9S-

Local Mean
Solar Time.

Local Sidereal
Time.

Greenwich
Sidereal Time.

Local Tabular
Distance of
Centers of Sun
and Venus.

ESEESS. h m s

h m s

h m s

h m s

/ rt

Internal " Geome- 1
trical '' Contact - J

22. 27. 42-8

22.30. l8'85

i5. 41.32-39

II. I.58-8g

i5. 41*16

External Contact

22. 58. ig'2

23. o. 55-43

16. 12. 14-01

1 1. 32. 40-5 1

16.44-88

Whence the final equations —

For Internal " Geometrical " Contact —
+ 4"'24 = +o"-ioo6 n — -ig5g 8 R.A. — -9772 8 N.P.D. +o"-o3i7 8 t — 8 R + 8 r,

and for External Contact —

+ 3"-36 = + o"-og54 n —-2972 8 R.A. —'9467 8 N.P.D. + o"-oZ-j2 8 t — 8 R — 8 r.

G. L. T.

3 i 2

OBSERVATIONS

AT

OBSERVATORY BAT, KERGUELEN ISLAND,

IN TABULAR ARRANGEMENT.

428

TRANSIT OF VENUS, 1874. KEEGUELEN ISLAND.

TABLE I. — COLLIMATION of the TRANSIT INSTRUMENT by REVERSAL on the NORTH DISTANT MARK.

1874,
Local Mean Time.

Position mill
Reading of the
Micrometer.

Zero of
Collimatiou.

1874,
Local Mean Time.

Position and
Reading of the
Micrometer.

Zero of
Collimation .

b

r

r

h

i

r

November 16

....

[20-549]

December 20, 75

W. 21-709

'7

[20-549]

E. 19-384

20-545

W. 21-703

'9> 7

E. 20-811

W. 20-288

2o-55o

20, I 5$

W. 21-751

E. 19- 404

20-579

10

W. 20-001

W. 2i-758

[20-555]

E. 21-129

20- 566

W. 20 • 006

22, 2

W. 21-704

23

....

[20-522]

E. 19-426
W. 21-710

[20-563]

24, 10

z Octantis S.P.

20-5i3

22, 6

§
W. 21-290

25

W. 20-77!

E. 19-841

20-564

E. 20-370

20-571

W. 21-283

W. 20-772

24, 6

W. 2I-25I

December 4

W. 20-837

20-586

E. 19-876

[20-565]

E. 20-357

W. 21 -25-;

7

....

[20-572]

17.17

W. 20-927

8

....

[20-568]

E. 20-203

20-562

10

[20-558]

W. 20-913

[20-567]

28, 61

W. 10-938

II

....

[20-553]

E. 20-189

20-563

i5

• » • •

[20-532]

E. 20-170

20-556

1 6, n£

E. 19-688

W. 20-943

W. 21-366

[20-517]

3i, 8

W. 21-288

E. 19-689

E. 19-903

20-591

17, 73

W. 21-358

[20-527]

W. 21-171

[20-576]

E. 19-684

3l, 12

W. 20-527

18, 7

W. 21-309 *

E. 20 • 607

20- 567

E. 19-757

[2o-53o]

' j
E. 20-619

W. 2i-3o3

20-570

W. 20-Sll

18, 7

W. 19-891 f

1875.

E. 21-175

20-528

January 9

W. 21-354

W. 19-873

E. 19-696

20-532

20, i

W. 21-649

W. 21-383

E. 19-423

20-538

10

W. 21-349

W. 21-658

[20-555]

E. 19-800

20-574

* " Mark at present used for Azimuth."
f " Another mark.'

§ December 22, 6h. Moved the East Pivot towards the South,
t Image of wires reflected from mercury.

OBSERVATIONS AT OBSERVATORY BAY.

429

Table I. — Collimation of the Transit Instrument — continued.

1875,

Local Mean Time.

Position and
Beading of the
Micrometer.

Zero of
Collimation.

i875,
Local Mean Time.

Position and
Reading of the
Micrometer.

Zero of
Collimation.

h

r

T

h

January i z

W. 21-309 *
E. 19-830

20-569

February 8, 1 3

W. 20-539
E. 20-645 J

20-595"

'•

W. 20-554

16

W. 21-086

E. 20-043

20-56l

9, -H

W. 20-II5 §

W. 21-073

E. 2o-o5i

(20-084)

W. 20-118

[20-595]

'7

W. 21-104

E. 20-029

20-520

ii

W. 21-597

W. 21-077

[20-558]

E. 19-593

[20-592]

W. 21 • 593

22 f

W. 21-089

E. 20-067

[20-576]

II, 10

W. 2o-5oo

W. 21-062

E. 20-707 J

20-601

W. 20-492

23

\V. 21-100

E. 20-087
W. 2i-o63

20-584
[20-579]

«*, H

W. 21-503
E. 19-683
W. 21-478

[20-589]

26

W. 21- ii i
E. 20-072
W. 21-092

[20-587]

i3

W. 21-339
E. 19-839
W. 21-296

[20-586]

*7,

W. 2i-o36

'4

W. 2 1 ' 440

E. 20-169

20-597

E. 19-742

[20-583]

W. 21-016

W. 21-407

27, uj

W. 20-529 J
E. 20-639
W. 2o-53i

[20-590]

H

W. 20-510
E. 20-649 t
W. 20-527

20-584

29

W. 21-046
E. 2o-i35
W. 21-048

[20-588]

17

W. 21-196
E. 19-999
W. 21-187

[20-591]

18

[2o-593]

February 8( 6

W. 21-048
E. 20*149

20-598

'9

...

[20-597]

W. 21-048

21

[20-602]

* January 12. Daylight; misty.

t January 22. Evening. January 27. Evening.

J Image of wires reflected from mercury.
§ February 9. Probably W. 2t-u5.

430

TRANSIT OF VENUS, 1874. KERGUELEN ISLAND.

Table I. — Collimation of the Transit Instrument — concluded.

i875,
Local Mean Time.

Position and Zero f

Reading of the Collimation.
Micrometer.

i875,
Local Mean Time.

Position and
Reading of the
Micrometer.

Zero of
Collimation.

b

r r

h

t

,

February 23, 2j

W. 21-677 [20-609]

February 25 t

W. 20-236 §

*

E. 19-999

(2o-i38)

23, 2j

W. 21-290

W. 20-179

23 t

W. 21-322

E. 19-921 [20-609]

26

....

[2o-6o5]

W. 21-273
1

* February 23, 25''. The Level and Azimuth were adjusted. f Evening.
§ Probably W. 21-236.

TABLE II. — LEVEL ERROR of the TRANSIT INSTRUMENT at OBSERVATORY BAY, determined by
SPIRIT LEVEL.

[The sign + indicates that the East Pivot is low.]

Day.

Sidereal Time
of Level
Determination.

Level Error
corrected
for Inequality
of Pivots.

Day.

Sidereal Time
of Level
Determination.

Level Error
corrected
for Inequality
of Pivots.

1874.
November 1 5

h in

5.io

+ 6' 12

1874.
November 18

2. 12

+ 5-02

5. 3o

+ 6-19

2.25

+ 4-28

5. 5o

+ 5-i6

2.35

+ 1-24

6. 20

+ 6-34

3. o

+ 3-72

6.32

4- 5-56

3.io

+ 5- 14

6. 40

+ 6-08

6. 40

+ 5-o3

6.55

+ 6-64

7- o

+ 4'77

7. o

+ 6-23

>9

23. 0

+ 4-39

16

21.25

+ 7-62

4. o

+ 3-53

1.36

+ 5-97

4.10

+ 3-27

2. 0

+ 6-27

4-25

+ 3-42

2. 12

+ 6-76

5. o

+ a'74

3. o

+ 6-16

5.20

+ 3-27

3. 6

+ 5-48

5.55

+ 3-34

6. o

+ 5-77

6. 20

+ 3-46

17

22. 2O

3.io

+ 8-44
+ 8-93

6. 40

7- o

+ 3-19
+ 3-36

4- 5

+ 8-22

20

o. i5

+ 4-I7

5. o

+ 7'77

o. 3o

+ 5-74

6. 40

4- 9-00

3. o

+ 6-34

OBSERVATIONS AT OBSERVATORY BAY.

431

Table II. — Level Error of the Transit Instrument — continued.

Day.

Sidereal Time
of Level
Determination.

Level Error
corrected
for Inequality
of Pivots.

Day.

Sidereal Time
of Level
Determination.

Level Error
corrected
for Inequality
of Pivots.

1874.

h m

it

1874.

h m

„

November 22

5. 10

+ 3-94

November 3o

6. 3o

+ 2-47

5. 3o

+ 3-72

6.35

+ 5-5o

5. 5o

+ 4'i3

7- o

+ 3-22

6. o

+ 2-82

7- 5

+ 3-6o

6. 20

+ 1-83

7. 1 5

+ 5-63

7. o

+ 3-53

7-35

+ 5-32

7. 1 5

+ 3-76

7.40

+ 3-oo

December 3

3. o

+ 3-48

23

I. 20

+ 3-38

3. 5

+ 3-90

i. 35

+ 3-72

3.45

+ 2 -O2

2. 5

+ 4-20

4. 10

+ 3-32

2. 15

+ 4->7

4

o. 5o

+ 8-49

4.40

+ 3-53

1.40

+ 7-58

24

i. 40

+ 5-33

6

I 3. 20

+ 7'5o

i.5o

+ 5-89

2. O

+ S'97

7

5. 3o

+ 6-76

2. IO

+ 6 '49

6. o

+ 7-88

2.26 ?

+ 5-23

16. 14

+ lo'So

2.36

+ 2-42

16. 39

+ 11-67

25

I. 20

+ 4'58

8

23. 8

+ 11-07

i.5o

+ 4'73

23.40

+ g-83

6. 10

+ 3-27

23. 50

+ 9-76

5.43

+ 7 '24

26

I. 0

+ 6-38

5.58

+ 7-17

1.28

+ 5-52

6.25

+ 7'5o

6. 55

•}

1.44

+ 6-19

7 9

i.59

+ 5-67

7- 5

+ 7'54

2. 40

+ 5-82

7.3o

+ 7-32

3. o

+ 6-04

8. 20

+ 6-53

6.25

+ 4-69

10

3.45

+ 10-27

27

2.15?

+ 4' 06

4.i5

+ 9-97

2. 36?

+ 1-53

II

6. 20

- 2-73

2. 50

+ o-63

7- 1 5

— 2-40

3. 5o

- o-34

8. o

- 2-92

4. o

+ °'97

4. iS

+ 2-43

12

2. 0

- 3-63

4.25

+ 0-89

2. 40

- 3-37

6. 40

+ I'OI

2. 50

- 2-17

3 K

432

TRANSIT OF VENUS, 1874. KERGUELEN ISLAND.

Table II. — Level Error of the Transit Instrument — continued.

Day.

Sidereal Time
of Level
Determination.

Level Error
corrected
for Inequality
of Pivots.

Day.

Sidereal Time
of Level
Determination.

Level Error
corrected
for Inequality
of Pivots.

1874-
December 12

h m

3. o

— 2'2I

1874.
December 20

h m

19-25

+ o • 60

5. o

- 3-60

2-42

+ 1-24

5. IS

— 2'2I

2-46

- o-37

5. 3o

- 3-74

3-io

+ 0'72

5.45

- 1-87

3-58

+ I '09

4-iS

+ 1-47

i5

1.35

- 3-26

4-4°

+ 1-06

2. 17

- 2-36

5-40

+ 1-17

3.io

- 2-36

5-55

+ 0-79

3.45

— 2 '06

6-28

+ 0*76

5.55

- I '80

6-5o

+ 0-68

6.17

- 2-66

6. 3o

- 2-43

21

3. o
4. 25

+ 3-34
+ 2-93

16

Noon
2. So

— o'3o

+ O'll

5. 20
6. 10

+ 2-97

+ 2 * 20

3. o
3.45

- 1-72
- 2-92

22

....

^ 2 * 00

~~ i " OQ

4. o
5. o
5.25
5.45
6. S
6.25

- 2'58

— 2'02

- 2-36

— 2'2I
- I-9I

- 2'l3

5.33

7- 4
7.20

7-43
8.24

— 0-93

- 0-86
- 1-23

— I' 12

- o'86

6.35
7. 3o

8.20

- 2-66
- 2-54
- 2-61

23

5.45
6.35

+ i-So

24

2. 20

+ 2-82

18

2.45

- o-33

2. 4O

+ 3-o8

3. 7

— 0-78

2. 50

+ 3 '60

3. 3o

- 0-48

3.35

+ 3-34

3.47

— 0-41

5. o

- 0-26

26

2.59

O'OO

5. iS

— 0-22

9. So

- o-85

5.25

- O'4i

5.45

— O'26

27

5. 3o

— 2'o6

5. 55

— 0*22

5. So

- i -So

8. 20

- i-56

7. 10

- 1-23

8.25

- i-56

7.40

- 1-76

OBSERVATIONS AT OBSERVATORY BAY.

433

Table II. — Level Error of the Transit Instrument — continued.

Day.

Sidereal Time
of Level
Determination.

Level Error
corrected
for Inequality
of Pivots.

Day.

Sidereal Time
of Level
Determination.

Level Error
corrected
for Inequality
of Pivots.

1874.
December 27

h 111
8.20

//
- 2-17

i875.
January 4

- i -So

9. So

- 2'5l

- i-38

10. 20

- 2-28

10.44

- 2-66

5

4. o

- 1-42

4.35

— 2' 06

28

6. 3o

- 2'28

5. 3

- 0-86

7. 10

— 2'2I

5. So

- 1-23

8.25

— 2-12

5.55

- i-57

29

6. 40

- 2-66

6. 20

- i-57

22. O

- 1-91

'7

5.20

— I'OI

3o

5.35

- 1-87

5. 3o

- 0-86

5. So

- 2-36

.

g

6.35

- 0-35

6. 1 8

— 2 '40

6.55

— o'6o

6. 3o

- 2-24

6.55

- 2-28

7.40

— I'OI

8. o

— 1-27

7. o

— 2-20

8. iS

- 0-82

7.25

— 2'20

7-45

- 0-86

9

4.3o

+ o-83

5. to

•f i '62

3i

5. o

- 1-68

5. 10

— i -80

5. 40

+ 1-28

6. 5

+ o-38

5.20

— 2' 06

5. 3o

- I-64

10

5. 5

+ i'i3

6. 20

— 2'2I

5.40

+ 1-92

1875.

6. 10

+ I'20

January j i

....

— 2 '40

....

- 2-84

ii

6. 16

+ I '24

6.40

+ I'S4

2

4. 10

- 2-32

7- o

+ 2'03

5.35

- 5-5i

7. 3o

+ 1-47

6. 10

- 6-71

7.35

+ i '54

7. So

- 4-5?

8. 10

+ 1-69

3

3.45

- 0-18

12

6. 40

+ 3-27

4. 10

- 0-78

6. 55

+ 3-23

4. 3o

— o-g3

4.55

- i -57

ii

0. 0

+ 4'24

5. 1 3

- i-S3

4.40

+ 2-59

5.35

- 1-76

5.20

+ 2-52

5. 55

- 1-87

5. So

+ 2'70

6.35

— I ' 12

6.42

- o-38

3 K2

434

TRANSIT OF VENUS, 1874. KEEGUELEN ISLAND.

Table II. — Level Error of the Transit Instrument — continued.

Day.

Sidereal Time
of Level
Determination.

Level Error
corrected
for Inequality
of Pivots.

Day.

Sidereal Time
of Level
Determination.

Level Error
corrected
for Inequality
of Pivots.

1875.

h m

„

1875.

b m

H

January 14

o. 40

+ 6'86

January 23

9. So

- 3-37

o. 45

+ to-38

IO. IO

- 3-Sz

IO. 20

- 3-56

16

7-25

+ 7-57

12. 2O

- 3-78

8.20

+ 5-07

9. 10

+ 5-52

25

8. 24

- 4-7*

....

+ 6-72

8.24

— 4' 4-^

....

+ 6-79

12. 15

- 4-83

17

3.55

+ 7-88

12. 40

- 5-13

4- *

+ 8-40

4-36

+ 6-76

26

4. 3o

- 4-83

5. 5

+ 6-60

5.25

- 4-23

5. 3o

+ 6'oo

6. o

- 4'38

5. So

+ 6-00

6.25

- 3-26

6. 20

+ 6'oo

6.42

— 2- 10

12. 5

— 3-oo

it

+ 5 " o 3

12. 15

- 3-78

....

+ 5 ' 97

12.40

- 3-o3

13. 20

- 2-81

19

- 3-33

....

- 3-07

27

7.25

- 2-77

20

....

- 4-34

7.40

- 2-73

....

- 3-88

9. o

- 3-n

9.40

— 2-96

21

5.20

- 2-81

13. o

- 2-84

5. So

— 2-62

13.25

- 3-i4

6. 59

- 2-77

8. 20

- 5-21

28

6. o

- 3-41

8.40

- 4' 64

29

5.55

- 1-83

22

9.25

— 4-01

6. 20

— I ' 12

9. 3o

- 4-46

6.45

- 1-61

23

22.55

- 4-46

7- o

- i-3i

4. 3o

- 2'5l

14.40

- 2-17

S.io

- 3-74

iS. o

- 2-28

5. So

- 3-56

6. i5

- 3-o3

3o

+ 0-04

6.45

- 3-82

....

— 0' II

8. o

- 3-56

8.20

- 2'l3

31

6.43

— i '46

8. So

— 2-96

16. o

— I 'oi

OBSERVATIONS AT OBSERVATORY BAY.

435

Table II. — Level Error of the Transit Instrument — continued.

Day.

Sidereal Time
of Level
Determination.

Level Error
corrected
for Inequality
of Pivots.

Day.

Sidereal Time
of Level
Determination.

Level Error
corrected
for Inequality
of Pivots.

1875.

h m

,/

1875.

h m

H

February 2

6. 3o

+ I -60

February 1 2

2.45

- 3-62

6.45

+ i-73

5. 5o

- 5-96

7- °

+ i'69

6. 20

- 5-58

9. o

- 5-7o

3

5.55

+ 2-97

6.25

+ 3-o8

i3

3.35

- 2-24

6. So

+ 4-39

3. So

- 2-32

8. i5

+ 3-57

5.40

- 2-28

5. 5o

- 3-io

4

• • . •

+ 5-22

....

+ 5'48

H

7- 5

- 3-48

5

5. So

+ 6-49

7.40

- 3-77

6. 5

+ 6-57

8. iS

- 2-58

6.25

+ 3-52

8. 45

- 3-48

6.45

+ 6-60

i5

5. 52

— I * QO

7. o

+ 6-04

6

7- 5

- 5-24

16

6. o

- 0.92

8. 1 5

— 4' 20

6. i5

- 1-67

7

6. 20

- 4-3i

'7

6. 1 5

- 2-17

6. 45

- 4-64

7. 10

— 2-46

7- o

- 4-72

7.3o

- 2-58

7. 3o

- 4'46

7.55

- 3-o7

7.40

- 3'oo

8. iS

- 4'*7

8

8. 20

- 5-58

8.40

- 4-01

8. 3o

- 5-o6

9. 3o

- 4-34

it

6,40

- 1-42

9.45

- 5-55

MS

- 2-39

10. 5

- 5-io

8. i5

- 1-08

0. O

- i-38

9

o. 5

- 7-64

3.47

- 5'88

'9

8. o

- 5-77

12. 30

- 5-56

8. iS

- 6-86

10

• . • I

- 6'97

8. 3o

- 6'it

-

....

- 6-93

8.45

— 6 '07

9. 20

- 6-,4

n

5.45

- 7-38

9. 3o

- 5'92

5. 55

- 7-04

9.40

- 6-26

6. 20

- 7-04

IO. O

- 6-o3

7- o

- 7-01

10. 3o

- 6-33

436

TRANSIT OF VENUS, 1874. KERGUELEN ISLAND.

Table II Level Error of the Transit Instrument — concluded.

Day.

Sidereal Time
of Level
Determination.

Level Error
corrected
for Inequality
of Pivots.

Day.

Sidereal Time
of Level
Determination.

Level Error
corrected
for Inequality
of Pivots.

1875.
February 20

h m

6.25

- 5-84

i875.
February 23

h m

o. 42

- 0'74

6.45

- 5-io

i3. 10

- i-38

10. 5

— 5-40

14. 1 5

- 1-23

10. 3o

- 5-i3

25

8. 3o

- °'97

21

8. i5

- 5-58

9- 20

— o-3o

10. i5

- 5-24

26

IO. 20

— 0-90

n. 35

- 5-70

14. o

- 1-61

14.35

- 1-72

22

6.25
6.45

7- °
7. 10

— io-5o

— 10-12
-10-23
— lO'OI

16. 5

- 1-16

The Micrometer was West in every instance except the
following : —
November 21, 6h. 20™.
November 24, 2h. 36m.

From November 27, 2h. 36m., to December 3, 4h. iom.
December 10.

TABLE III. — AZIMUTH ERROR of the TRANSIT INSTRUMENT.

[The sign + indicates that the Optic Axis points East of North.]

Day,

and Local
Mean Solar Time.

^

Azimuth Error.

Observed.

Adopted.

1874.

h m

November 15,14. 36
16

17,12.43
12. So
14.19

1 8, 14. 24
19, 14.20

20

<s Octantis S.P.

Aldebaran and
o Trianguli S.P
<r Octantis S.P.

a- Octantis S.P.
a Octantis S.P.

-14-18

- 3-33
-11-78
-13-94

- o-73
+ i-o3

— 14-2
- 8-0

J

- 0-7
+ 1-0

+ I'D

and Sirius

OBSERVATIONS AT OBSERVATORY BAY.

437

Table III. — Azimuth Error of the Transit Instrument — continued.

Day,
and Local
Mean Solar Time.

Stars.

Azimuth Error.

Observed.

Adopted.

1874.

h m

November 22, 14. 8
23, 9. 3o

12. 26

24, 10. 1 5
25, 9. 16

26, 9. 34
10. 7
i3.52
27, 10. 3
13.48
3o, 13.44

December 3
4, 8.41

6

7,23. 3i

8,:3. 3
i5. 3

10
II, 12. 50

12, 9. 6
12.46

15,12. 34

17, 12.29
14.27

1 8, 8.40

14.24
20, 8. 36

21. 18

zi, 10. 3o
12, 14. 8

+ 0-91
+ 14-80
+ 14' 5o
+ 9'66
+ 7-45
+ 4-25
+ 5-62
+ 9-09
+ 3-67
+ 3-23
+ 11-71
+ 12-33
+ 25-54
+ 27-33

+ 39-46
+ 39-62

+ 37-22

+ 36-22

+ 35-10
+ 34-29
+ 32-19

+ 37-12
+ 36-05
+ 33-52
+ 3?-65
+ 39-88
+ 38-23
- 4-88
- 5-25
— 6-01

- 2'l3

- 5-oi
- 6-75
-21-85
— 21-04

- 3-88

//
+ 0-9

+ 9-0

+ 7-4
+ 4'9

} .,,

} *-

+ 26-4
+ 39-5
} +39'i
+ 38-3
} +36-7

+ 34-3
+ 35'2
I +36-o

+ 37-6
+ 39-9
+ 38-2

1 -

} -

-21-7

— 12-0

- 3-8

0 Ceti and o Trianguli S.P

67 Ceti and o Trianguli S.P

v Piscium and z Octantis S P

67 Ceti and z Octantis S.P

ff Octautis S P and Sirius

z Octantis S P and o Ceti

7' Eridani and a Octantis S.P

z Octantis S.P. and 8 Arietis

z Octantis S.P. and A Octantis

a Octantis S.P. and « Canis Majoris

438

TRANSIT OF VENUS, 1874. KERGUELEN ISLAND.

Table III. — Azimuth Error of the Transit Instrument — continued.

Day,

and Local
Mean Solar Time.

Stars.

Azimuth Error.

Observed.

Adopted.

1874.

I. m

December 24, 8. 17
27,13.48
28, 11.44
13.44

3i, ii. 32

1875.
January 8, 12. 5g

10, 10. 55

i3, 9. 5
10.43

16, 12. 3o
13.25
i3.25

17, 10. 27

21, 12. 9

23,10. 3

12. O
12. 5l

26, 9. Si

27, 12. 36
29, 9.40

11.38

z Octantis S.P. and a Ceti

//

+ 0-52

+ 16-89
+ 18-86

+ 17-02
+ 13-07

+ 3-76
-16-76

- 4'37
- 2-92

- 2'54

+ 10-26

+ i 3 • 04

+ 14- 12
+ IO-4O

- 2-18

+ 4'79

+ 4 '06

+ 2-58
+ 2-88
+ 2-99

+ 4-18
+ 1-82

+11-02
+ 9-49
+ 6-41

//
+ 0-5

+ 16-9

I +17-0

+ 3-8

-16-7
- 4'3

} -"'

> + 12-2

+ I0'4
— 2-1

+ 4-8

L + 2-8

+ 4-2
+ 1-8

I + 9'5

Procyon and A Octantis

a Octantis S.P. and e Canis Majoris

a Octantis S.P. and A Octantis

y Canis Majoris and A Octantis

( Leporis and a Octantis S.P

Pollux and A Octantis

o Trianguli S.P. and t Leporis

a Columbse and a Octantis S.P

A Octantis and B Octantis S.P

f Hydra and B Octantis S.P

e Orionis and a Octantis S.P

<r Octantis S.P. and A Octantis

7 Geminorum and A Octantis

A Octantis and B Octantis S.P

Sirius and B Octantis S.P

a Octantis S.P. and A Octantis

Castor2 and A Octantis .

OBSERVATIONS AT OBSERVATORY BAY.

439

Table III. — Azimuth Error of the Transit Instrument — concluded.

Date,
and L. M. T.

Stars.

Azimuth Error.

Observed.

Adopted.

1875.

ii in

February 8, n. o A Octautis and TJ Cancri

ii. 49 A Octantis and B Octantis S.P

n. 49 € Hydrae and B Octantis S.P

9, 6. 3o Meridian Mark (uncertain)

11, 8.49 a Octantis S.P. and Sirius

12, 8. 25 Meridian Mark (uncertain)

S. 46 IT Octantis S.P. and Sirius

1 3, 8. 42 $ Orionis and IT Octantis S.P., Wire I

/3 Orionis and a Octantis S.P., Wire 2
0 Orionis and a Octantis S.P., Wire 3 .
$ Orionis and a Octantis S.P., Wire 4 ,

14, ii. 26 Procyon and B Octantis S.P

17, to. 22 Procyon and A Octautis

18, 10. 16 Pollux and A Octantis

19, 10. 12 6 Cancri and A Octantis

1 1. o A Octantis and B Octantis S.P

n. o B Octantis S.P. and 83 Cancri

ii, 10. o A Octantis and 17 Cancri

10. o A Octantis and C Octantis S.P

12. o C Octantis S.P. and p Leonis

22,12. o t Canis Majoris and C Octantis S.P.. ..

23 By Meridian Mark

25 By Meridian Mark

26, 1 5. 3o i) Boiitis and 0 Centauri

1 6. 5 Arcturus and a- Centauri

+ 9'2i
+ 5-46
+ 3-99

-i5'74

- 9-6

- 6-o3

-18-14

-23-34

— I2'5o

— 16-71
-11-48

- i-35

- 6-25

-i6-33
-i5-56
-15-27

-19-90
-i8-63

— l5'2I

— 37-10

+ 2-5

+ 7-2
+ 0-97

+ o- ii

+ 6-6

-i5-8

- 6-0

-18-1

-i5-6

-18-6

-37-i

+ 2-5
+ 7-2

+ o-5

* February 12 , The recorded time of observation of a Octantis S.P. has been diminished one minute.

3 L

440

TRANSIT OF VENUS, 1874. KERGUELEN ISLAND.

ABSTRACTS of TABLES IV. and V TRANSITS of STARS and of the MOON, and Inferred R.A. of the

MOON'S LIMB at TRANSIT.

1

4|

fl O

i

Reading and

II

1 1

^ « rf

Clock Slow

Clock's

g Clock Time of

Right Ascension

Day,

Position of

CO

*J

G *<£ *"

III

on Local

Losing

g Transit of

of Moon's Limb

1874.

Micrometer
Head.

|5

1 |

to*x
S. o

Sidereal
Time.

Rate.

*l

Moon's Limb
over Meridian.

at Transit
over Meridian.

|"o

§o xi

ft O

S 10

0

ft

to

S

3

rev.

h m

8

i

h in .

k - • •

Nov. 1 5

WS

2o-5oo W.

3

5.21

+ 46-04

+ 2-40

BS

20-548 W.

5

i

6.34

+ 46-07

16

WS

20-548 W.

2

1.47

+ 47-57

+ 2-40

BS

4

3.29

+ 48-01

I.

21. 23. 58-49

21. 24. 45-43

'7

P

20-555 W.

7

i

4.46

+ 5o-75

+ 2-43

I.

22. 17. 59-09

22. 18.48-95

18

BS

20-555 W.

4

2. 38

+ 53-00

+ 2-48

G

3

1

6.41

+ 53-37

'9

f

20-555 W.

2

23. 5

+ 54-63

+ 2"5o

WS

4

4. 12

+ 55-3o

p

4

5. i3

+ 55-40

G

3

1

6. 5o

+ 55-90

20

G

. 2

2. 46

(+57-97)

+ 2-47

22

WS

4

5.28

( + 63-09)

+ 2-34

P

20-555 E.

i

P

20- 555 W.

5

«

7.i5

+ 63-28

23

G

5

i.39

+ 65-04

+ 2-63

II.

3. 58.23-20

3. 59.28-16

24

BS

20-555 W.

4

i

i. 53

+ 67-97

+ 3-14

20- 555 E.

i

26

G

20-555 W.

10

2

2. 50

+ 14-97

+ 3-21

3o

BS

20-555 E.

6

6. 56

+ 27-65

+ 3-25

Dec. 3

BS

20-555 E.

5

3. 36

(+36-I8)

+ 3-39

4

P

20- 555 W.

4

i. 18

+ 39-30

+ 3-23

6

WS

20-555 W.

i

i3. 18

( + 46-65)

+ 3-07

7

WS

20-555 W.

3

12.49

+ 5o-o2

+ 3-17

8

WS

20-555 W.

3

23.35

( + 5i-6i)

WS

5

2

6.42

+52-32

+ 3-19

10

BS

20-555 E.

3

3. 58

(+58-39)

+ 3-n

ii

p

20-555 W.

3

2

6. So

+ 6i-83

+ 3- 10

12

BS

20-555 W.

7

2

4.22

+ 64-63

+ 3-14

i5

G

20-555 W.

5

2.37

( + 73-92)

+ 3-28

WS

4

I

6. 29

+ 74-43

"7

B8

20-555 W.

4

3.29

( + 20-68)

+ 3-33

WS

8

2

6. 4

+ 21-07

OBSERVATIONS AT OBSERVATORY BAY.

441

Abstracts of Tables IV. and V Transits of Stars and of the Moon, &c. — continued.

Day,

1874.

Observer.

Heading and
Position of
Micrometer
Head.

Number of Transits 1
of Clock Stars.

Number of Transits 1
of Circumpolar 1
Stars.

<v <«

B
— "

•1*5

a 3

g'oO
S

Clock Slow
on Local
Sidereal
Time.

Clock's
Losing
Rate.

i
1

o-g

•a «

d 'SI

Clock Time of
Transit of
Moon's Limb
over Meridian.

Right Ascension
of Moon's Limb
at Transit
over Meridian.

rev.

u ui

s

i

h in a

h in s

Dec. :8 G

20 '527 W.

7

i

3.29

+ 23-99

+ 3-26

ws

6

i

5.32

+ 24-34

20

WB

20' 527 W.

i

G

12

i

5. 12

+ 30-49

+ 3-26

21

p

20 '527 \V.

5

5.i9

( + 32-34)

+ 3-38

I.

4. 28. 22-O8

4. 28. 54-I4

22

G

20-537 W.

9

i

7- H

+ 37-54

+ 3-19

23

P

20-537 W.

3

6.23

( + 40-78)

+ 2-87

24

G

20-537 W.

3

i

3. i3

+ 43-26

+ 2-92

*7

1>

20-537 W.

7

i

6.53

+ 53-17

+ 3-53

G

I

II.

10.39. 9'7"

10.40. 3*44

28

WS

20-537 W.

4

2

6.54

+ 56-69

+ 3-43

3o

WS

20-566 W.

6

I

3i

WS

20- 566 W.

5

I

6. 6

+ 65-92

+ 3-14

1875.

Jan. g

C

20-566 W.

6

I

7.20

+ 32-79

+ 2-72

10

CC

20-566 W.

9

I

5.40

+ 38-42

+ 3-42

13

CC
CC

20-566 W.
20-566 E.

7

2

I
I

}5.39

+ 48-33

+ 3-38

16

CC

20-564 W.

3

2

8.3i

+ 59-16

+ 3-72

'7

C

20-564 W.

7

I

4.59

+ 62-40

+ 3-75

I.

4. o. 5z-37

4. 1.54-84

21

P

20-564 W.

9

I

6. 22

+ i 6 • 60

+ 3-5o

22

WS

20-564 W.

I.

II.

No stars.

442

TRANSIT OF VENUS, 1874. KERQUELEN ISLAND.

Abstracts of Tables IV. and V.— Transits of Stars and of the Moon, &c. — continued.

Day,

1875.

Observer.

Reading and
Position of
Micrometer
Head.

Number of Transits 1
of Clock Stars.

Number of Transits
of Circumpolar
Stars.

1*3

H

tfi

111

•Sfi35
8

1 °

Clock Slow
on Local
Sidereal
Time.

Clock's
Losing
Rate.

o

c
o
o

3 "

Clock Time of
Transit of
Moon's Limb
over Meridian.

Right Ascension
of Moon's Limb
at Transit
over Meridian.

rfv.

b in

S

s

h in s

tl 111 S

Jan. 23

c

20- 564 AY.

8

i

5.29

+ 23-41

+ 3-59

c

7

2

ii. 27

+ 24-27

II.

10. i5. 52-29

10. 16. i6-53

26

c

20 -5 64 W.

9

I

5. 8

+ 33-95

+ 3-34

c

3

12.32

( + 34-95)

II.

12.35. 7-99

12. 35. 42-96

27

p
p

2o-564W.
2o-53o W.

6
i

'1

10. I

+ 38-42

+ 3-6o

II.

13.19. 5-52

i3. 19. 44- 18

p

22-728 W.

i

J

29

c

20-564 W.

9

2

6.58

+ 44-80

+ 3-34

II.

No Stars.

Feb. 8

p

20- 564 W.

7

I

9- '9

+ 20-96

+ 3-64

•ws

I

9

cc

20-563 W.

I.

No Stars.

cc

20-564 W.

i

ii

p

20-564 W.

5

I

6.28

+ 30-76

+ 3-39

12

cc

20- 564 W.

8

I

7- 8

(+34-24)

+ 3-5o

I.

2.42. 54-90

2. 43. 28-02

i3

c

20-564 W.

4

5. 10

(+38-oi)

+ 3-73

I.

3.41. 55-12

3.42. 33-o8

c

17-504 \V.

I

c

17-997 W.

I

c

i8-683 \V.

I

c

iS-863 W.

I

'4

p

20-564 W.

6

I

7- Si

+ 41-78

+ 3-76

'7

p

20-587 W.

8

I

7.26

+ 53-12

+ 3-91

I.

7. 5?. 13-69

7.58. 5-58

18

cc

20-587 W.

12

I

8. 2

+ 57-I5

+ 3-65

I.

8.56. 2-74

8. 37. o- ii

OBSERVATIONS AT OBSERVATORY BAY.

443

Abstracts of Tables IV. and V. — Transits of Stars and of the Moon, &c. — concluded.

&

Of) *M flj *«-<

11 a °

o

Reading and S |

• s. s

| a ^ 2 ..

Clock Slow

Clock's

e
§

Clock Time of

Right Ascension

Day,

Position of ^ °°

O ^i

«".! Ill

on Local

Losing

1

Transit of

of Moon's Limb

i875.

S

Micrometer ^ S

u .'2£cc

g on" 02 ^

Sidereal

Rate.

'S'S

Moon's Limb

at Transit

g

Head. |»

•o a a o

Time.

_o £

over Meridian.

over Meridian.

£

§ -

ItSoa g*8u

.§ °°

O

!Q

fc 3

H

rev.

h m

h m s

h in a

Feb. 19

c

20-587W. 7

2 9. 10

+ 60-64

+ 3-53

I.

9. 5o. 24-94

9. Si. 25-81

II.

9. 52. 39-60

9. 53.40-66

21

cc

20- 587 W. 9

2 10. 48

+ 8-56

+ 3-69

II.

ii. 3o. 58-41

ii. 3i. 7- 14

23

•ws

20- 587 W. 2

14. 5

+ 3-27

II.

1 3. o. 24-92

i3. 0.40-18

26

cc

20- 586 W. 7

i3. 26

+ 26-39

+ 3-68

II.

1 5. 1 8. 59-22

i5. 19. 26-08

TABLE VI. — LONGITUDE of OBSERVATORY BAY, KERGUELEN ISLAND, from the OBSERVED RIGHT

ASCENSION of the MOON on the MERIDIAN.

Observed

Longitude by the

13
g

R.A. of

Ephemeris.

Adopted

Resulting

Day.

£

CD
00

Moon's Limb

€ = the Correction

Value

Longitude,

Remarks.

<o
E

i

,0

on the
Meridian.

required to the Moon's
Tabular R.A.

ofe.

East of
Greenwich.

i

V

*

0

i-'

1874.

h m a

h

,

h m 1

Nov. 1 6

BS

I.

21. 24.45-43

4. 39. 33-27 + 26*20 e

-o-3i

4. 39. zS'i

7

Daylight. Clock-error deter-

mined 5 hours after the

lunar observation, and no

star observed for azimuth-

error. Azimuth unsteady.

'7

P

I.

22. 18.48-95

33*24 + 27-03 <

-o-33

24-3

6

Daylight. Clock and azimuth-

errors determined 5 hours

after the lunar observation.

Azimuth unsteady. Other-

wise good observation.

23

G

II.

3.59.28-I6

50-84 +21 -82 f

-0-71

35-3

21

Good observation ; hazy

clouds. Clock and azimuth-

errors satisfactory.

Dec. 21

P

I.

4. 28. 54-I4

46-57 + 21-66 e

-0-66

32-3

21

Clock-error depends on two

stars near the Moon. No

determination of azimuth-

error. Azimuth very un-

steady.

27

O

II.

10.40. 3-44

4. 39. 57-61 +29-85 «

-0-81

4.39.33-4

II

Clock-error depends on a

single star near the Moon.

Azimuth satisfactory and

otherwise good observation ;

daylight.

444

TRANSIT OP VENUS, 1874. KEBQUELEN ISLAND.

Table VI. — Longitude of Observatory Bay, from the observed R.A. of the Moon on the Meridian — concluded.

Observed

Longitude by the

"8

R.A. of

Ephemeris.

Adopted

Resulting

Day.

c

1

Moon's Limb

e = the Correction

Value

Longitude,

Remarks.

H

0

on the

required to the Moon's

of e.

East of

ID

D

1

1

Meridian.

Tabular R.A.

Greenwich.

'S
*

0

i875.

h u, 1

h m s

I

h m a

Jan. 17

c

I.

4. I. 54-84

4. 39.44-89 + 22-90 e

-0-55

4. 39. 32-3

'9

Good observation, through

haze ; clock and azimuth-

errors satisfactory.

22

WS

[1

| ....

....

••

....

••

No stars observed.

23

C

II.

10. 16. i6-53

42-45 + 28-3O €

-o-58

26-0

i5

Good observation ; clock and

azimuth-errors satisfactory.

26

C

II.

12. 35.42-96

49-I8 + 32-79 «

-0-47

33-8

9

Good observation ; clock and

azimuth-errors satisfactory.

17

p

II.

i3. 19.44-18

39'l3 + 32-6l f

-0-44

24' 8

6

Moon observed on four wires,

at two of which the limb

was scarcely visible. Clock

and azimuth-errors satis-

factory.

29

cc

II.

. • . .

... >

....

Moon observed on one wire

only, and no stars with it.

Feb. 9

cc

I.

* . • .

. » • .

. ,

....

. ,

No stars observed with the

Moon.

12

cc

I.

2.43. 28-02

45-75 + 25'oof

— 0-46

33-2

ii

Clock and azimuth-errors de-

termined 3 hours after the

lunar observation. Azi-

muth very unsteady. Good

observation otherwise.

i3

c

I.

3.42.33-08

49-84 + 23-62 e

-0-52

37-6

18

Clock-error applied depends

upon a single star near

the Moon. Azimuth-error

satisfactory and good ob-

servation.

i?

p

I.

7.58. 5-58

4. 39. 5o- 55 + 23 -62 €

— o'6i

36-i

18

Much tremor. Clock and

azimuth-errors satisfactory.

18

CO

I.

8.57. o-n

4.40. 10-17 + 25-42 f

— 0-60

54-9

16

Fair observation. Clock and

azimuth-errors satisfactory.

("Limb very unsteady. Clock

19

c

I.

9. 5i. 25-8i

4.40. 5-78 + 27-52 €

-o-58

49-8

7

inaudible from high wind ;
J B S marking seconds.

I Otherwise clock and azi-

„

„

II.

9. 53. 40-66

4. 39. 53-94+27-52 e

-o-58

38-o

7

muth - errors satisfactory.

(_ Moon's II. defective.

21

cc

II.

ii. 3i. 7-14

38-75 + 31-25 f

-o-53

18-2

10

Good observation. Clock and

azimuth-errors satisfactory.

23

ws

II.

i3. 0.40-18

43-I3 + 32-43 e

— 0-45

28-5

5

Moon observed at two wires

only ; clock correction de-

pends upon two stars which

are discordant. No deter-

mination of azimuth-error.

26

cc

II.

i5. 19. 26-08

4. 39. 37-39 + 28-98 f

-o-35

4. 39.27-2

12

Good observation ; clock and

"•'

azimuth errors satisfactory.

OBSERVATIONS AT OBSERVATORY BAY.

445

TABLE VII. — ABSTRACT of LONGITUDES of OBSERVATORY BAY, from the OBSERVED AZIMUTHS of the

MOON'S Fmsx LIMB.

CLASS A. — STARS OBSERVED WITH THE MOON.

1874-75.

Number of Obser-
vations = 11.

Mean Inferred
Longitude from
each Day's
Observations.

Mean Difference
of Tabular Azi-
muth = a.

•?

Cl

a

t

I

Remarks.

Observer, W S. Moon's I. L.

h m s

a

November 1 5

3

4. 39. 28-6

Si

17

Cloudy at times.

16

5

43'0

33

24

}> limb very unsteady. Cloudy.

i?

2

34-9

34

16

5 limb much serrated. Cloudy.

iS

4

25-7

41

34

Fair observations.

19

2

33-9

42

25

J limb well denned.

22

4

40-4

38

29

Cloudy, but fair observations.

23

2

4i-5

29

12

Good observations.

December 1 5

2

26-8

40

23

Snowstorms. J limb well denned.

17

2

3o-5

40

23

Fair observations.

18

6

29-7

40

39

}) limb well defined.

20

3

40 '5

37

24

}> limb bright and clear.

January 10

3

34-9

33

>9

Daylight ; J limb bright and well denned.

i3

4

3i-6

37

27

Clear.

21

February i i

2

3

40-6
40 '8

35
36

'7

22

High wind : Lieut. Coke calling seconds. Defective
limb.
High wind : Mr. Smith calling seconds.

12

4

42-0

36

26

High wind : clock often inaudible.

H

2

35-i

35

'7

Observed in a momentary interval between clouds.

18

2

4.39.55-8

35

9

Driving haze. J limb very ill denned. Clock
often inaudible.

Mean with weights, 4''. 39™. 3 5s '26.

Observer, G. Moon's I. L.

h m «

tr

December 17

2

4. 39. 29-8

40

23

J> limb very unsteady.

18

6

4. 39.34-2

40

39

High wind.

Mean with weights, 4''. 39°'. 32s' 56.

446

TRANSIT OP VENUS, 1874. KERGUELEN ISLAND.

Table VII. — continued.

1^

Mean Inferred

a, <5

R

1874-75.

Number of
vations =

Longitude from
each Day's
Observations.

S| ii

s°s I
s

.S3

Remarks.

Observer, B S. Moon's I. L.

h m s

„

February i 9

2

4-39-38-3

35

17

3) limb much serrated. Clock often inaudible.

CLASS B. — No STARS OBSERVED WITH THE MOON.

Observer, P. Moon's I. L.

h m a

„

November 19

4

4. 39.27-2

38

29

20

2

14-1

42

25

Cloudy.

21

»

3o-5

41

34

High wind. Clock often inaudible.

January i 3

4

4. 39. 33-o

36

26

Clear.

Mean with weights, 4h. 39™. 26" -6.

Observer, C C. Moon's I. L.

h m s

„

January 17

2

4.39.33-3

36

18

February 1 1

2

4. 39.42-0

36

18

Mean with weights, 4h. 39™. 37* -7.

Observer, W S. Moon's I. L.

h M .

„

November 2^

4

4- 39. 26-4

42

35

Haze, but j) limb well defined.

Observer, B S. Moon's I. L.

h m s

If

February 18

2

4. 39 46-3

34

16

5 limb serrated. Clock almost inaudible.

OBSERVATIONS AT OBSERVATORY BAY.

447

TABLE VII. (continued). — ABSTRACT of LONGITUDES of OBSERVATORY BAY, from the observed

AZIMUTHS of the MOON'S SECOND LIMB.

CLASS A. — STARS OBSERVED WITH THE MOON.

i 874-75.

Number of Obser-
vations = ».

Mean Inferred
Longitude from
each Day's
Observations.

Mean Difference
of Tabular Azi-
muth = a.

K

"a

1

9

Remarks.

Observer, W S. Moon's II. L.

h m »

„

November 23

2

4.39.48-2

39

21

Haze.

*4

2

34-8

36

18

Clear. ]> limb good.

26

2

27-9

34

16

J) limb well defined, but faint.

January 21

2

28-2

35

17

High wind : Lieut. Coke calling seconds.

23

4

29-6

35

24

Fair observations.

23

2

28-5

25

9

J> limb not good.

27

2

3o-7

3i

'4

Haze ; )) limb unsteady and woolly.

29

2

38-o

28

ii

}) limb serrated and unsteady.

February 21

4

29-9

33

22

Good observations.

21

2

4.39.22-7

25

9

Good observations.

Mean with weights, 4h. 39'". 32s -54.

CLASS B. — No STAR OBSERVED WITH THE MOON.

Observer, P. Moon's II. L.

h m s

„

January 23

3

4.39.I2-3

35

21

High wind ; clock inaudible.

27

2

4. 39. I9-I

35

17

High wind ; clock almost inaudible.

Mean with weights, 4''. 39'". i5" 3.

Observer, C C. Moon's II. L.

h m s

„

January 26

2

4. 39. 29-8

38

2O

High wind ; clock almost inaudible.

3 M

448

TRANSIT OF VENUS, 1874. KERGUELEN ISLAND.

Table MIL— concluded.

b

Si

1874-75.

o s

CM il
° »

•£'£

I?

K

Mean Inferred
Longitude from
each Day's
Observations.

S| n

^ J3

G S

go S

Weight a?Vn.

Remarks.

Observer, W S. Moon's II. L.

h in s

it

November 3o

4

4.39.44-9

3i

'9

High wind ; clock inaudible.

December 24

2

41-6

35

17

Through thick haze.

27

5

38-i

33

24

Haze. J limb sometimes good.

28

2

28-1

32

'4

High wind ; clock often inaudible.

3i

7

33-4

33

29

Cloud, j limb well defined sometimes.

January 26

2

4.39.33-3

32

14

High wind. Mr. Smith calling seconds.

Mean with weights, 4h. 39™. 36»- 8.

Observer, B S. Moon's II. L.

h m s

„

January 27

2

4. Sg. 29-6

33

i5

High wind.

TRANSIT OF VENUS, 1874.

PART IV.

EXPEDITION TO KERGUELEN ISLAND

(continued).

Section 2.

OBSERVATIONS AT SUPPLY BAY, EOYAL SOUND,

By LIEUTENANT CYRIL CORBET, R.N.,

AND

LIEUTENANT GK ELMSLEY COKE, R.N.
With One Plate.

3 M2

450

CONTENTS.

Establishment at Supply Bay 451

Instruments 452

Clock, Chronometers, and Transit 453

Transits of Stars ' 454

Errors and Rates of the Transit-Clock 457

Altazimuth, and Latitude of Supply Bay 458

Gunpowder flashes for Longitude 460

Longitude of Supply Bay 461

Observations of the Transit of Venus by Lieut. C. Corbet . . , .-. . . 461

Observations by Lieut. G. E. Coke 462

Comparisons of Lieut. Coke's Chronometer 463

Equations derived from the Observations 464

Plate XVII. toface 462

451

ESTABLISHMENT AT SUPPLY BAY.

It was at first thought to be possible to establish a station on Heard Island
which should depend, as regards longitude and base of operations, upon the
head station on Kerguelen Island. Lieutenants Cyril Corbet and Gr. Elmsley
Coke, R.N., accompanied the expedition under the Reverend S. J. Perry
with this object in view, and also to conduct the chronometric connections.

After the arrival of the Expedition in Kerguelen Island, it was found that
the idea of occupying Heard Island must be abandoned. Not only were the
reports of the masters of the sealing vessels very unfavourable, but it was
doubtful whether the amount of fuel carried by the ships would be sufficient
for the trips to be made for the longitude connection.

Mr. Corbet, therefore, assisted by Staff Commander Inglis, R.N., com-
manding H.M.S. Supply, explored the S.W. portion of Royal Sound ; and
having fixed upon a sheltered inlet (near to the isthmus called " Swain's
Haulover "), which he named " Supply Bay," for the position of his station (see
the map, Plate XVI.), he proceeded to establish an independent observatory
there.

They arrived on their ground in the Supply, 1874, November 5 ; and, with
assistance from the ships, the little station (consisting of a dwelling-house,
observatory, and storehouse) was built and equipped by November 11, when
the Supply returned to the better anchorage, leaving at the new station
Sub-Lieut. Baynes, a servant, and a cook.

To establish a record of the locality, Lieut. Corbet subsequently took the
following bearings from the Transit Instrument : —

Cross bearings, corrected to the Astronomical Meridian, taken from the Transit Instrument.

o /

Extreme of Island in the center of Harbour, at high water S. 89. 3o. E.

Do. do. do. S. 77. o. E.

Point at Southern entrance to Harbour S. 72. 40. E.

Extreme of a bold lump on the top of the Hill to the Southward. The
lump being about the highest spot to the Southward, of bold rock,

with a little lichen over it S. 6. 3o. E.

Extreme of the highest bold cliff on the top of the hills to the West and

N. West N. 46. o. W.

Mount Wyville Thompson S. 79. 40. E.

[The attached symbols in the MS. appear to denote that No. i was at the left hand, and
Nos. 2, 4, 5 at the right hand. — G. B. A.]

452 TRANSIT OF VENUS, 1874. KERGUELEN ISLAND. SUPPLY BAV.

Lieut. Corbet was provided with the following instruments : —

A portable transit instrument.

A portable altazimuth.

An astronomical clock.

12 chronometers.

A 4-inch achromatic telescope, on tripod stand, by Simms.

A 3J-inch achromatic telescope, on tripod stand, by Dollond (lent from
the Cambridge Observatory).

Mercurial and aneroid barometers, thermometers, prismatic com-
pass, &c.

Observations for local time, with both the transit instrument and the
altazimuth, were as continuous as the bad weather permitted, from Decem-
ber 4 to December 21 ; and the latitude was sufficiently well determined.

On December 17 Mr. Corbet left the station in charge of Mr. Coke, and
commenced the work of connecting the various stations with the chrono-
meters. On December 21 he returned and dismantled the station.

The clock by Baker was lent by the Council of the Royal Astronomical
Society. The pendulum was compensated on the gridiron principle. The
movements were put into good repair before leaving England.

The following is a list of the chronometers : —

A. Arnold 536.

B. McCabe 36o.

C. Loseby n3.

D. Poole3i64.

E. Dent 1981.

F. Hewitt 991.

G. Frodsham and Baker 6149.
H. Frodsham andBaker6i88.

/. Dent 1916.
m. Muston 6 1 1 .
n. Molyneux 1061.
S. Kullberg 2177.
Z. C. Frodsham 6004.

The portable transit, kindly lent by H. Kains Jackson, Esq., of Orpington,
is by Troughton and Simms, of three inches aperture. It was supported
on an iron stand, which was intended to rest upon a pier of masonry.

CLOCK, CHRONOMETERS, AND TRANSIT. 453

At Supply Bay a pier of brick and cement was built, on a foundation of
concrete, on hard ground; but Lieut. Corbet placed between the masonry
and the iron stand a block of wood, to which the iron stand was screwed ;
apparently to facilitate fastening down the latter.

On November 20 a furious gale blew off the roof of the observatory, and the
transit was knocked out of its Y's, and fell to the floor on its eye-end and
setting circle, which was much bent. This being straightened with the
hands, the instrument was found to be apparently but little the worse for
the accident.

The correction for inequality of pivots was carefully determined. It was
found to be 0"'ll (+ lamp B., — lamp W.), which has been applied to all
the level errors given in the following tables.

The error of collimation is determined by observations of stars with
reversed positions of the transit axis. It appears that Lieut. Corbet was in
the habit of testing the stability of the collimation and azimuth errors, by
directing the telescope to and reversing it on a distant terrestrial object ; but
the instrument having no micrometer, he could not of course make accurate
observations in this manner. He appears to have had no suspicion that
anything was wrong with the instrument, but was puzzled at the apparent
instability of the azimuthal position.

I have no doubt that in this case, as with all the other transits made by
Troughton and Simms, the ring clamp at the eye end of the telescope, which
fixed the wire plate, had worked loose during the voyage, and consequently
the system of wires was not rigidly fixed with reference to the optical axis.
It is of course possible that the object-glass was loosely attached, but it is
improbable, from the mode of attachment. No record is to be found of any
special examination of the instrument.

With the instrument in this condition, with the additional fault of being
mounted on a block of wood, in a climate where heavy rains and fierce winds
perpetually alternated, good observations for local time were impossible.

The value of the divisions of the hanging spirit-level was determined by
the makers before leaving England, and again on the return of the expedition
to Greenwich ; 40 divisions were found equal to one minute of arc. The
level error was generally large, but the determination of local time is not
injuriously affected on this account.

It follows from the description of the instrument and its mounting that
the azimuth error can never be inferred with any certainty. It has been
computed in every possible way from the observations.

454 TRANSIT OF VENUS, 1874. KERGUELEN ISLAND. SUPPLY BAY.
TRANSITS of STARS observed at SUPPLY BAY, KERGUELEN ISLAND.

Day.

Observer.

Position of j
Lamp.

Star's Name.

Number of
Wires.

Mean observed
Transit over
Center Wire.

True Transit
over
Meridian.

Seconds of
Star's
Apparent
R.A.

Clock
apparently
Slow.

1874.
Dec. 4

CC

E

W

z Octa
a Ceti
8 Arie
7i Eri
o} Eric
a Tria
,3 Orio

ntis S.P

I
5
5
5
5

2
2

h m a

2. 27. 5ro
2. 55. 58-6
3. 4.42-2
3.52.26-8
4. 6. o-i
4. 35. 23'q
5. 8.43-8

s
1067

61-1

45-3
287
2-3

32-4

46-5

8

3o-5

45'2

29'4
12-6
46-5

21'2

32-6

3

— l6'2

— 1 5-9
— 1 5-9
- 1 6- 1
- 1 5-8

— I I'2
— 1 3'9

tis

iani

lani

ng. Aust. S.P.
nis

Error of Level.

By s Octantis i
o1 Eridani I
Time Stars,

Error of Azimuth.

//

3i

63
59

Sidereal
Time.

Lamp.

Level Error.

S.P., Lamp E., and a Ceti E. . . . +
I., and a. Triang. Aust. S.P. E.. . +
Lamp E +

h m
2. 40
3.25
4. 2O

5. 18

E.
E.
E.
W.

n

+ 6-64
+ 6-27
+ 5-33
+ 2-36

;/

Adopted, -f 5o-o

*

Day.

Observer.

Position of
Lamp.

Star's Name.

Number of

Wires.

Mean observed
Transit over
Center Wire.

True Transit
over
Meridian.

Seconds of
Starr's
Apparent
R.A.

Clock
apparently
Slow.

'874-
Dec. 8

CC

W
E

i Octa
71 Eri
«Tau
a Tria
a Tria
€ Lepc
/3Oric
/STau
8 Orio
a Lep
<• Orio

ntis S.P
Jani

5
3

4

2
2
5

5
5
5

i
5

h m 8
2. 29-38-2

3.52.36-3
4. 29. 10-8
4. 35. 53'4
4. 35. 52-i
5. o. 35-7
5. 8.57-5
5. 1 8. 5o-g
5. 26. 3-4
5.27.38-5
5. 3o. 18-2

m s
28. l8'9

36-8

9'9
45-9
46-3
35-g
57- 1
48-8
2-6
38-5
'7'4

s

02'5
I2'6

45-5

21-3
21-3

II-2

32-6
24-1

37-9
i3-9

52-9

s

+ 1 3-6
- 24-1

— 24'4
— 24-5

— 25-0

- 247

— 24-5
— 24-6

- 247

— 24-6
— 24-5

ri

ng. Aust. S.P.
ng. Aust. S.P.
>ris

nis

ri

ois

Dris

nis

Error of Level.

By y1 Eridani,
a Triang. ^
a Triang. 1
Time Stars
Time Stars

Error of Azimuth.

//

7
28
29
39
26

Sidereal
Time.

Lamp.

Level Error.

Lamp W., and z Octantis S.P. W. +
Lust. S.P. W., and ?> Eridani W. —
Lust. S.P. E., and <• Leporis E. . . —

h m

3. 41
4. u
4. 5o
5. 14

W.

W.

E.
E.

//

+ 22-24
+ 22'05

+ 22-3g
+ 22-g5

//
Adopted, — 28-5

TRANSITS OF STARS.

455

Day.

Observer.

Position of
Lamp.

Star's Name.

Number of
Wires.

Mean observed
Transit over
Center Wire.

True Transit
over
Meridian.

Seconds of
Star's
Apparent
K.A.

Clock
apparently
Slow.

1874.
Dec. 12

CC

E
W
E

z Octantis S.P
5,2 Ceti

3
5
5
5
5
5
5
5
5

2
2

b m 3

2. 28. 3o-g

2. 37. 16-9
2. 56. I2'3

3. 4.56-6
3. 40. 3 i'o
3. 02. 38*5
4. 6. 12-5
4. 21. 45-5

4- 29- "'4
4. 35. 49-0
4. 35. 47-5

s
54-g
19-4
14-8
5g-i
33-5
42-6
,6-7

497
1 5-6
60-2
52-g

s

34-2

45-2
29-4

12-6

46-6

'97
45-6

21-5
21-5

s

— 29-6
— 29-6

- 297
— 29-6

— 3o-o
'— 3o-i
— 3o-o
— 3o-o
- 28-7

«Cet
8 Ari
, Tai
y1 El-
s' En
« Ta«
a, Tai
a. Tri
a Tri

i

3tis

iri

idani

dani

ri

iri

ang. Aust. S.P.
ang. Aust. S.P.

Error of Level.

By z Octantis '
y2 Ceti E. a
a, Ceti E. ar
71 Eridani 1
Time Stars,
Time Stars,

Error of Azimuth.

E.... +

47
38
38
62
35
40

Sidereal
Time.

Lamp.

Level Error.

>.P., Lamp E., and y2 Ceti
nd & Triang. Aust. S.P. E.
d a. Triang. Aust. S.P. E.
V. and a Triang. Aust. S.P
Lamp E. .

h m

2.33
2.47
3.23
4. o
4-47

E.
E.
E.
W.
E.

+ 28-95
+ 3o-o8

+ 32-92
+ 33-27

. W. . +

-i-

Lamp W. . 4-

Adopted, 4- 38-o

Day.

Observer.

Position of
Lamp.

Star's Name.

Number of
Wires.

Mean observed
Transit over
Center Wire.

True Transit
over
Meridian.

Seconds of
Star's
Apparent
K.A.

Clock
apparently
Slow.

1874.
Dec. 17

GE C

E
W

E

a. Ceti
8 Arie
•n Tau
yl Eri
o1 Eric
e Taui
a Tau
a Tria
e Lepc
0 One
a- Octi

5
5
5
5
5

4
5
5

4
5

2

h m s

2. 56. 30-4
3. 5. i3'8
3. 40. 46-3
3. 52. 57-2
4. 6. 30-7
4.22. 2-9
4. 29. 28-9
4.35. 57-1
5. o. 58'7
5. 9. 19-0
6. 9.49-7

m s
33-9

1 8-3
52-9
6r5
35-3
9-1

7i-5
61-2

22-2
14.47-6

s

45-2

63-g
12-6
46-6
19-8
45-6
21-7

U'2

32-7
24-0

s '
- 487

- 49'o
- 48-9
— 48-8

- 49-8
— 5o-o

- 49'5
— 83-6

tis

ri

dani

lani

•J

ri

ng. Aust. S.P.
tris

nis

tntis S.P. . . .

Error of Level.

By a Triangul
€ Leporis
j3 Orionis E.
Time Stars,
Time Stars,

Error of Azimuth.

and

. 4- i

i'i

'O

>]

.3

Sidereal
Time.

Lamp.

Level Error.

i Aust. S.P., Lamp E.,
E

h m
2.45

3.23

4-49
6.26

E.
E.
E.
E.

n

+ 0-27
+ 3-27
+ io'3g
+ 11-14

and <r Octanti
Lamp E. .

s S.P. E + -

4- if

Lamp W + (

Adopted, + 80-0

3 N

456 TRANSIT OF VENUS, 1874. KEKGUELEN ISLAND. SUPPLY BAY.

Day.

Observer.

Position of
Lamp.

Star's Name.

Number of
Wires.

Mean observed
Transit over
Center Wire.

True Transit
over
Meridian.

Seconds of
Star's
Apparent
K.A.

Clock
apparently
Slow.

1874.
Dec. 1 8

GEC

K
W

E
W

E

zOct

a. Ceti
i) Tau
e Tau
e Lep<
$ Ork
/3 Tau
8 Orio
a Ork
<r Oct
y Gen
a Can

iritis S.P. . . .

2

5

4

2

5
3
i
5
3
3
5

U m s
2. 28. 5 I' I

2. 56.32-0
3. 40. 5o'3
4. 22. 8'5
5. i. o-6
5. 9.21-7
5. 19. 11-9
5. 26. 2o'5
5. 49. 1 2'5
6. i5. i3'6
6. 3i. 19-5
6. 40. 28-9

HI .S

8 1-6
35-9
54-5
10-8
2-6
23-g
16-0
29-3
1 6-4
14.43-9
21-8
3o-q

3

37-i
40-2

3'9
197

I1'2

32-7
24-3
38-i

25'I

24-3
3o-2

39'2

s
- 44-0

- 5o7
— 5o-6
— 5ri
- 01-4

— Jl'2

— 5i-7

- 5l'2

— 5 1 -3

— 79'6
— 5r6

- 517

ri

ri . .

jris

mis

ri

nis

mis

antis S.P

linoruni

's Majoris . . .

Error of Level.

By z Octantis 5
a. Orionis VS
Time Stars,
Time Stars,

Error of Azimuth.

//

44
3i

28

47

Sidereal
Time.

Lamp.

Level Error.

4.P., Lamp E.,
f. and a- Octam
Lami) AV

and a Ceti W +
is S.P. W. . +

h m

2.44
4. 0
4.41
6.26

6. 5i

E.
W.
E.
W.
E.

a

+ 22-02
+ 24-86
+ 26-89

+ 25-99
+ 26-52

4-

Lamp E {-

u
Adopted, -f 38'o

Day.

Observer.

Position of
Lamp.

Star's Name.

Number of
Wires.

Moan observed
Transit over
Center Wire.

Truc Transit
over
Meridian.

Seconds of
Star's
Apparent
K.A.

Clock
apparently
Slow.

1874-
Dec. 20

GEC

W

E

q Taui
71 Eri
o1 Erk
e Taui
e Lepc
/3 Oric
/3 Tnu
8 Orio
f Orio
a Orio

0- Oct£

"i

5
5
5
5

2

5
5

5

2

5
3

h m s

3. 40. 57-0
3. 53. 9-7
4. 6. 42-6
4. 22. i3-6
5. i. 10-5
5. g. 3o-o
5. iq. 18-7
5. 26. .75-3
5. 3o. 5o-o
5. 40. 21 -6
6. 7. 18-8

m s
627
Il-g
43-4
l8-7

10-8
3i*5
23-3
37-5

52'2
24-4
14. 2o'6

s

3'9

I2'6

46-6

'97
1 1-3

02-7
24-3
38-i
53-i

25-1

25-o

3

- 58-8
— 5q-3
— 58-8
— 59-0
— 5q-5
— 58-8
— 5g-o

— 59'4
— 89-;

— 5q-3
- ")8-6

hiiii

lani

i

mis

nis

nis

intis S.P

Error of Level.

By o- Octnntis f
Time Stars,
Time Stars,

Error of Azimuth.

//

79
65

9'

Sidereal
Time.

Lamp.

Level Error.

5.P., Lamp E., and ft Orionis E.. +

h m

3.47
4.42
6.24

W.

E.
E.

//

— 2q-52
- 23-74

— 2 I'll

Lamp E +

Adopted, + 78-5

TRANSITS OF STARS. ERRORS OF THE TRANSIT CLOCK.

457

Day.

Observer.

Position of
Lamp.

Star's Name.

Number of
Wires.

Mean observed
Transit over
Center Wire.

True Transit
over

Meridian.

Seconds of
Star's
Apparent
K.A.

Clock

apparently
Slow.

1874.
Dec. 21

GEC

E
W

E

ft Orio
S Orio
e Orio
a. Oric
a- Octr
€ Carii
y Can
S Gem
a2 Gei
a Can
j3 (Jen
6 Can

nis

5
i
o

3
3
3
5
5
5
5
5
5
5

h m s

5. 9. 33'4
5. 26. 38-5
5. 3o. 53-6
5. 49. 24/2
6. i3. 25-7
6. 04. 42-8
6.59. 6-3
7. 13.39-4
7.27.37-3
7.33.47-1
7. 38. 41-3
7. 56. 52-3

s

35'O
40-2

55-3
27-5
io-5
45-9
9'4
42-7
41-0

48-9
40-2
54-1

8

327
38-i
53-o

25' I

25-4
43-8

40-3
38-3
46-2
40-8

5l'2

s

— 62-3
— 62-1
- 62-3
— 62-4

— '4'9
— 62-1

- 62-3
— 62-4
- 62-7
- 62-7
— 62-4
— 62-9

nis

nis

nis

ntis 8. P. . .

s Majoris ....
s Majoris. . . .
inorum. . .

ninorum ....
s Minoris . . .
linoriim

3ri

Error of Level.

By a- Octantis S
Time Stars,
Time Stars,

Error of Azimuth.

55

23
21

Sidereal
Time.

Lamp.

Level Error.

.P., Lamp W., and c Can. Maj. W. +

h m
5.58

7- 8

7-48

w.

w.

E.

//

+ 1774
+ 16-99
+ 18-64

Lamp E +

//
Adopted, + 33"o

ERRORS and BATES of the TRANSIT CLOCK.

Date.

Lamp K. or W.

Sidereal Time.

Clock Slow.

Clock's Apparent
Losing Rate.

Adopted Losing
Rate.

1874.
December 4

t
8

12

'7

E.
W.

W.
E.

E.
W.

E.
W.

h m

3.29
5. 9

»
— 1 5'go
— l3'93

s

-r37
— i'35

— 3-87

«

- 1-86
-2-61
- 2-40

4- 19

- '4'94

4. 10
5. 1 8

- H-27
- 24-09

4.44

- 24-43

3. 4

4. 12

— 29-62

— oO'Ol

3.38

- 29-82

4. 2
4. 5

- 49-28
- 4.9-04

4- 4 — 49''6

458 TRANSIT OF VENUS, 1874. KERGUELEN ISLAND. SUPPLY BAY.

Date.

Lamp E. or W.

Sidereal Time.

Clock Slow.

Clock's Apparent
Losing Rate.

Adopted Losing
Rate.

1874.
Dec. 1 8

20
21

w.

E.

W.

E.

E.

4.37
5.3z

— 5 1 -08
— 5r3g

- 2-17
— 3'gi

-3-6i

S

-275
-3-7i

5. 5

— 61-24

4. o

5. 22

— 58-g8
— 5g-i8

4.41

— 5q-o8

6.32
6. 52

— 62-45
— 62-36

6.42

— 62-41

The portable altazimuth, also by Troughton and Simms, was lent by
Mr. Warren De la Rue. The vertical circle was 12 inches in diameter, and
was read by two micrometer-microscopes to single seconds of arc. These
microscopes were supported at the extremity of a horizontal bar forming a
portion of the solid casting of the revolving body. There was one sensitive
zenith distance level, graduated with 40 divisions to the minute. There
appears to have been one vertical and one horizontal wire.

This altazimuth was mounted close to the transit-instrument and under the
game roof, and with it the following results were obtained for colatitude : —

Day.

Star.

Approx.
Z. D.

Apparent
Co-latitude.

Day.

Star.

Approx.
Z. D.

Apparent
Co-latitude.

1874.
Nov. 1 6
18

(3 Orionis. . . .

0 /

41. 10 N.

35 3gN.

o / //

40. 2g. 6*5
40. 28. 5i"2

1874.
Nov. 26

27

o1 Eridani . . .
a Ceti ,

0 /

42. 21 N.
53. 7 N.

Q t If

40. 2g. 2'6

4O. 2Q. 3*2

23

6 Ceti

40. 41 N.

40. 20. 7-8

o1 Eridani . . .

42. 21 N.

40. 28. 5g'i

y Piscium . . .
67 Ceti

54. 22 N.

42. 3i N.

40. 2g. 6-g

40. 2Q. I I"7

Dec. 2

aTriang.Aust.
•y1 Eridani . . .

61.41 S.
35. 3g N.

40. 28. 5o*4
40. 20. 3*7

I2 Ceti . . .

57. 25 N.

4O. 2Q. 7*4-

o1 Eridani . . .

42. 21 N.

40. 28. 57-4

a Ceti

53 7 N.

4.O. 2Q. A-'A.

3

67 Ceti

42. 3 1 N.

4-O. 2Q. 7*2

•y^ Eridani

35. 3g N.

40. 28. 56*5

P Ceti

57. 24 N.

4.O. 2Q. I I "I

2/t

67 Ceti

42. 3i N.

4.O. 2Q. 2*1

'f Ceti

52. 14 N.

4.O. 2Q. 3*3

»n

f2 Ceti

57 25 N.

40. 28. 55-8

a. Ceti

53. 7 N.

4.O. 2Q. l3'4-

rf Ceti

52. i3N.

40. 28. 5q'o

y1 Eridani . . .

35. 3g N.

4O. 2Q. 8'2

a Ceti

53. 7 N.

40. 28. 5 1 -2

A.

a Ceti

53. 7 N.

A.Q. 2Q. 6*2

26

67 Ceti

42. 3i N.

40. 20. 7-8

y1 Eridaui . .

35. 3g N.

4O. 2Q. 3'O

f2 Ceti

57. 25 N.

40. 2Q. 14-7

a1 Eridani . . .

42. 21 N.

4O. 2Q. 4'O

i/2 fVti

52 i3 N

a Ceti ...

53. 7N.

4-O. 2Q. I 5* I

Mean .

4.O. 2Q. 2*4.

LONGITUDE OF SUPPLY BAY. 459

All the stars, except « Trianguli Australis, are on the North side of the
Zenith. It seems not improbable that the inferred colatitude is a second or
two too great.

The results are not so accordant as might have been expected with such an
instrument; possibly the discordances are due to the employment of two
microscopes only.

ON THE LONGITUDE OF SUPPLY BAY.

As previously arranged, on the evening of November 16 Lieut. Goodridge
ascended to the summit of Mussel Island, off the entrance of Observatory Bay,
and exploded a quantity of gunpowder at intervals of ten mimites, a pre-
paratory rocket being sent up at 8.30 p.m. The understanding was that
similar signals should be made by the American observers five minutes after
each of Lieut. Goodridge' s signals. The signals from Mussel Island, four in
number, were all seen at Observatory Bay, and from a repeating station at
Supply Bay ; the first three only at Molloy Point. The Molloy Point signals
were not seen at Observatory Bay, but were all seen at Supply Bay. The
powder flashes being invisible from Supply Bay observatory, Messrs. Coke
and Baynes ascended a hill about half a mile distant, whence all the signals
were visible. Having their fowling pieces on full cock, they discharged them
immediately they perceived the signals, and estimated at once, independently,
the loss of time incurred by this repetition. Lieut. Corbet registered the
instant of hearing the gunshots. The distance of the repeating station was
afterwards measured, and Messrs. Coke and Baynes made a number of
experiments to determine the value of their estimates of the loss of time in
repeating.

The following are the times recorded and inferred difference of longitude
between Supply Bay and Observatory Bay, and between Supply Bay and
Molloy Point. Professor S. Newcomb kindly supplies the local mean times
observed at Molloy Point.

460

TRANSIT OF VENUS, 1874. KERGUELEN ISLAND. SUPPLY BAY.

RECORDED TIMES of GUNPOWDER FLASHES in EOYAL SOUND, and inferred

LONGITUDE of SUPPLY BAY.

Inferred Inferred

"oS
g

§

V

|

TJ

1

Recorded
Clock
Time.

Clock
Correction.

Local
Sidereal
Time.

Local
Menu Solar
Time.

Supply Bay . Supply
West of Bay West
Observatory of Molloy

ft

I

O

0

O

Bay.

Point.

"1

h m s

m s

h m s h in s

m s

m s

^

cc

O

o. 46. 42-20

+ 0.47-93

o. 47. 3o-i8 9. 5. i3'2

jj

.•i

o. 56. 40-8

+o. 47-95

o. 57. 28-75 9. 1 5. io- 1

w

^

in

i

i. 6.42-8

+o. 47-97

i. 7.30-77

9. 25. IO'O

g

0

•
H

i. 16. 41-5

+0.47-98

1.17. 29-48

g. 35. 7-6

(

H

b>

•

M

§

o. 45. i3'8

+ 2. l6-37

o. 47.30-17

9. 5. i3-2

M

m

cc

0

o. 55. i3-o

+ 2. 16-43

o. 57. 29-43

9. i5. 10-8

3

<!

PQ

N

i. 5. 14-8

+ 2. 16-49

I. 7.31-29

g. 25. i ro

H

2

1

i. 1 5. i3-o

+ 2. 1 6-56

I. 17. 29-56

9. 35. 7-6

i

o

o. 44. 38-o*

+ 2. 27-02

0. 47. 2'02

9. 4. 45-0

o. 28-20

I. IO"2

«

.4

^

—3-0

HH

•«
pq

-|

o. 54. 3g-o

+ 2 27-09

o. 57. 3-og

9- '4-44-4

o. 26-00

i. i3'i

V}

O

BQ

—3-0

en

5

£

o

M

i. 4. 3q-5

+ 2. 27-16

i. 7. 3-36

9. 24. 43- 1

o. 27-60

i. i5'i

r-!

E

j§

-3-3

tn

O

I. 14. 40-0?

+ 2. 27-22

i. 17. 4-12

g. 34. 42-2?

o. 25-40

* -

0 H

j "

(Communicated by Professor

9. 6. 0-2
9. 1 5. 57-5 .

o S

Simon Newcomb.)

g. 25. 58-2

*

(4th lost.)

05
3

O H

S S

(Communicated by Professor

g. 12. 23-2

g

O

Simon Newcomb.)

9. 19. 8'2
g.34. 12-7

M

g

O

H

IB

o. 5 1 • 4*0

4-2. 27-07

o. 53. 27-37

g. ii. g-3

. ,

i. 1 3-g

PH

m

. -3'7

O

(M

o

•S

o. 57. 5o*o

+ 2. 27-10

i. o. 14-10

9- !/-54'9

I.I3-3

M

3

E

o

^

-3-o

0

N

D

8

I. 12. 55'5

+ 2. 27-20

i. 1 5. 19-40

9.32.57-8

i. 14-9

CC

5

-3-3

* The corrections applied to the times by Clock Baker at Supply Bay are the estimated loss of time in repeating
the signal + 2" 5, the time required by sound to travel from the repeating elation to the Observatory.

CORBET'S OBSERVATION OF THE TRANSIT. 461

For the longitude of Supply Bay we have therefore —

i

1874, November 16, by powder flashes, Supply Buy West of

Observatory Bay 26*82

December 17, by chronometers (see page 471) 26-16

December 21 „ ( „ ) 26-22

Adopted Supply Bay West of Observatory Bay 26-5

h m a

Observatory Bay East of Greenwich 4. 3g. 33"5

Supply Bay East of Greenwich 4. 3g. 7-0

It will be remarked that this longitude depends essentially on observations
of transits made with the transit-instrument at Supply Bay, which was not
in the best possible order.

Gr. L. T.

OBSERVATIONS OF THE TRANSIT OF VENDS.

REPORT of LIEUTENANT CYRIL CORBET, R.N., on his OBSERVATION of the TRANSIT
of VENUS, 1874, December 8, at SUPPLY BAY, Royal Sound, Kerguelen Island.

[The telescope used by Lieut. Corbet was a new achromatic, by Messrs.
Troughton and Simrns, of 4 inches aperture. It was fitted with a solar
reflecting diagonal prism, and was mounted upon a tripod stand with hori-
zontal and vertical motions, and slow movements in both directions by
means of convenient handles.]

Time by the

Sidereal Clock

Baker.

11. 49. 43-5. First appearance of Venus on the Sun's disk. I do not think I could have- been

more than a minute late. The Sun's limb was steady, and the External Contact
occurred just where I expected.

12. i . 25-o. Venus estimated to be half way on.

12. 14.14-8. Venus being rather more than three-quarters on, I first snw its following limb
outside the Sun, a very faint ring of light distinctly marking it out.

12. 18. 56-1. I could still distinctly see the following limb of Venus, faintly illuminated and
nearly coinciding with the Sun's limb. No bluntness to the cusps as yet
(Plate XVII., Fig. i).

462 TRANSIT OF VENUS, 1874. KERGUELEN ISLAND. SUPPLY BAY.

Time by the

Sidereal Clock

Baker.

h ra s

12. 19. 26'8. This I believe to be the moment of true contact ; the cusps were just beginning to
shake and get blunt \ \ so, and I could distinctly see Venus' second limb,

with its faint light streak in perfect contact with the Sun's limb (Plate XVII.,
Fig. 2).

12. 19. 5ro. At this moment the black drop, if any, for there was very little, was at its biggest
or greatest stretch and about to break ; but I could all along, since the last
recorded time, distinctly see Venus' limb inside the Sun's, and only a slight
shaky black shade between the two (Plate XVII., Fig. 3).

12. 20. 8-o. At this moment there was no more shade between the two limbs ; it disappeared.

Venus never assumed a pear shape. I did not see any brightness or
wavyness to the planet's preceding limb while it was on the Sun. The
illumination of the outer or following limb was a steady brownish-white
light, with black speckles here and there, like irregularities on the planet's
surface, quite distinct ; and so it remained until all shade had disappeared
between it and the Sun's limb, when it disappeared also.

I used an Airy eye-piece for the correction of atmospheric dispersion, of
power 145, the solar reflecting prism, and a blue achromatised wedge. The
sun never shone with full brightness. Occasionally thin filmy clouds passed
over it. The wedge was not moved during the observation of ingress.

Twenty minutes or half an hour afterwards it clouded over hopelessly.

[CYRIL CORBET.]

REPORT of LIEUTENANT Gr. B. COKE, R.N., on his OBSERVATION of the TRANSIT
of VENUS, 1874, December 8, at SUPPLY BAY.

[The telescope used by Lieut. Coke was an achromatic of 3 J inches aperture
and 46 inches focal length, by Dollond, lent from the Cambridge Observatory.
It was mounted, with vertical and horizontal motions, upon a tripod stand.
The telescope was not fitted with any special means for viewing the Sun,
beyond " dark heads " to screw on to the eye-pieces.]

My telescope was situated about 95 yards to the east of the observatory,
near the water's edge ; the legs of the stand were imbedded about 6 inches in
the ground, and rested upon foundations of stone. Mr. Smith Dorrien
recorded the time from the sidereal cKronometer S.

The sun being covered by a transparent cloud, I began to observe with a
power of 61, without a dark glass.

Transit of Verms 181$ December 8.

XVU.

Obsa-vcOwns at Supply Say, l&rgudenJ klantl ly Lieat. C. Corbet RJf. weth a- telescope of ti inches

aperture , power J45.

Iiiyress, Fig. 1 .

Ingress, Fig. 2.

Ingress ,Fig. 3.

Observations at Supply Buy, KerywienX kUmd by lunlmant GE. Gke . R. If.

aperture, power 150.

a. telescope o

Intfress , Fig. #.

Ingress ,Fiy 5.

.l:'H ?2 BU'0«0 S'COVCHT

COKE'S OBSERVATION OF THE TRANSIT. CHRONOMETER COMPARISONS. 463

b m s

8. 1 1. 2 1 -5. I first perceived a break in the Sun's limb. Not trustworthy. I then changed
the power to 149, with the lightest red glass, and saw that the planet had
encroached on the limb. As I did not follow the planet until it became
uumistakeable, 1 have marked this observation as not trustworthy ; but I
believe it to bo correct.

8. 40. 5o'2. The planet appeared to be drawing out into the shape of a pear. I was at this
instant obliged to remove the dark glass, and then I no longer saw the appear-
ance of "drawing out." It was perfectly round, with a small portion still
without the Sun's limb.

8. 43. 4-5. The planet's limb appeared to be just touching the Sun's limb, a faint ligament
joining them (Plate XVII., Fig. 4). I believe this to be the actual time of
contact. The limb of the planet was very distinct and beautifully illuminated,
like a very young Moon. The brightness gradually disappeared towards the
center of the planet. I do not remember to have noticed this illumination
outside the Sun's limb. Whilst in contact there was a species of film, or
shadow, fora short distance on each side of the point of contact, which joined
the limbs, but did not appear to form a part of Venus, as it was much lighter
than the planet. This film gradually disappeared.

8. 43. ig-5. The film or ligament getting lighter (Plate XVII., Fig. 5).

8. 43. 46-5. It disappeared. No dark glass used.

The "black drop " never properly formed; only a dark film. I consider
that contact took place at 8h. 43'". 4S>5. I saw the limbs of the planet and of
the Sun very distinctly.

[G. ELMSLEY COKE.]

COMPARISONS of the SIDEREAL CHRONOMETER S. with the SIDEREAL CLOCK Baker,
by the Intervention of the SOLAR CHRONOMETER m, at SUPPLY BAY, 1874,
December 8.

Time by Clock
Baker at
Comparison
with m.

Adopted
Crrrection
to Bultrr.

Time by Solar

At Comparison
with Baher.

Chronometer m.

At Comparison
with S.

Time by Sidereal
Chronometer S.
at Comparison
with m.

Inferred
Correction of
Chronometer S.

i , ;

h m s

8

h m 3

n m s

h m s

h m s

10. 6. 26-0

— 24 85

i. 23. 3o'5

i. 24. 5o-o

6. 3l. q-0

+ 3.36. u-86

10. 29. 24-0

- 24-88

i. 46. 24-5

I. 37. 26-0

6. 43. 47-0

+ 3.36. i2-i5

12. 47. 33-o

— 25-c6

4. 4. io-5

4. q. 26-0

9. 16. i r5o

+ 3.36. 12-80

3 o

464 TKANSIT OF VENUS, 1874. KERGUELEN ISLAND. SUPPLY BAY.

The observations of Ingress at Supply Bay give the following results,
assuming the Latitude 49°. 30'. 56" S., Longitude 4°. 39'. 7"-0 Bast of
Greenwich : —

Local Tubular

Local

Greenwich

Distance of

Observer.

Phenomenon observed.

Recorded
Time.

Sidereal
Time.

Sidereal
Time.

Centers of
Sun and

Vemis.

h m s

h m s

h m s

/ //

Corbet

" True contact "

12. 19. 26-8

12. iq. i -8

7. OQ. J4'8

l5.3q-47

Coke

" True contact "

8. 43. 4' 5

12. iq. I7'I

7. 40. IO'I

i5. oq-oo

Corbet-

" Black drop at greatest ~i

stretch, and about to >

12. 19. 5r

12. 19. z6'o

7. 40. ig'o

i5.38'7i

break " ]

Coke

" Film o-ettintf lighter"

8. A.3. ip'5

12. IQ. 32'1

7. 40. 25' i

1 5. 38-53

Corbet

" The shade between the "1
limbs disappeared" /

12.20. 8'

12. ig. 43'O

7. 40. 36'o

i5. 38-21

Coke

" The film disappeared " . . . .

8. 43. 46-5

12. 19. og'i

7. 40. 02*1

i5. 37-70

Hence the final equations for the disappearance of the shade between
the limbs, taking E = 976"-80, r = 31"'42, and mean solar parallax =

8"-950 (l + 4)-

Corbet, +f'-\J = — o"'2i52 n +-5984 SR.A. — 76io8KP.D. — o"-o3c>4& t — <1 II 4 S r.
Coke, +7"-65= -o"-2i52w -»- -5977.8 R.A. -7617 8 N.P.I). -o"-o3o4S t - S Jl + 8 r.

G. L. T.

TRANSIT OF VENUS, 1874.

PART IV.
EXPEDITION TO KERGUELEN ISLAND

(continued) .

Section 3.

CHRONOMETRIC CONNECTIONS OF THE VARIOUS STATIONS

IN ROYAL SOUND.

By LIEUTENANT CYRIL CORBET, R.N.

3o 2

466

CONTENTS.

PAGE

Trips of the Volaye, with Chronometers 467

Comparison of Ship-Chronometer with Transit-Clocks . •• . • . ... . , 468

Adopted Errors of Ship-Chronometer *•...., ..... . 470

Inferred Differences of Longitude v , 471

467

CHRONOMETRIC CONNECTIONS OF THE STATIONS IN KERGUELEN ISLAND,

ROYAL SOUND.

The list of the chronometers supplied to Lieut. Corbet has been already
given. On December 15, all of them being lodged on board the Volage,
Lieut. Corbet commenced operations.

His method of proceeding was to compare the Sidereal Chronometer Z
with all the others by coincidence of beats ; I, m, n were then taken on shore,
compared with the transit-clock of the station, carried back to the ship, and
again compared with Z.

The Volage made the following trips : —

December 17d. 19h. left Observatory Bay ; called at Molloy Point (American
Station) 21h. 30m., at Thumb Peak December 18d. P., and at Supply Bay
December 18d. 5h. 39m. ; returned to Observatory Bay December 18d. 10h.

December 20". 17h. left Observatory Bay ; arrived at Thumb Peak 20*. 211'.,
Molloy Point 21rt. 2h. ; returned to Observatory Bay at 6h. 30'".

December 21d. 17h. left Observatory Bay ; arrived at Supply Bay 21d. 21h. ;
and returned to Observatory Bay 23(1. 8h.

December 29 left Observatory Bay 17h. 30m. ; arrived at Betsy Cove
(German Station) December 30d. 5h. ; left Betsy Cove 17h. ; returned to
Observatory Bay December 31A 4h.

Lieut. Corbet himself reduced the comparisons in the following manner : —
From the double comparisons of /, m, n with Z, and the comparisons of the
same three chronometers with the transit-clock of a station, the error of Z
on local sidereal time was found, assuming an error of the transit-clock.
The remaining chronometers A to H were treated as sidereal chronometers
with large losing rates, and their errors on local sidereal time inferred from
the comparisons with Z. The rates of the chronometers were inferred from
the comparisons at Observatory Bay, and the deduced longitudes of the
various stations were referred to Observatory Bay.

I examined Lieut. Corbet's work and found it to be correct. It was there-
fore only necessary to apply to his results the corrections due to the difference
between the clock-errors used by him and the clock-errors finally adopted-
For Molloy Point these were kindly supplied by Professor Newton, and for
Betsy Cove by Dr. Auwers.

[The mass of comparisons of the chronometers A to H with Z is very great.
I have not thought it necessary to print them. — G. B. A.]

408 TRANSIT OF VENUS, 1874. KERQUELEN ISLAND. ROYAL SOUND.

CHRONOMETRIC CONNECTIONS BY LIEUT. CORBET, K.N.

COMPARISONS of the SIDEREAL CHRONOMETER Z, retained always on board
H.M.S. Volage, with TRANSIT-CLOCKS at various Stations in ROYAL SOUND
and at BETSY COVE, by the Intervention of the Portable SOLAR CHRONO-
METERS I, TO, and 11.

<L | .i g g -z

id!

Time by the Portable' Chronometer.

§ o

S t

y

95.1

2-7 S
H a g

s "&

« — 0

'— ~' ^

|l

o^S

i t

ii

jill

z2 .

3 2;

S'Z 2 ^ : ? § ^

li

0 „

** 1

*• 3_u

c z .3 <j

a s.s

'Ss*

a °^" .0

s17* ^ s i S^B-P

si ^

*" "" CJ

_r.-> —

Ml

•3 jf-3 ,c

O'Sji "^ I ^ ~ 1 J

>.""* ^

•III

ill

5 — r-

llttl

fllJ

„ '* c 1 S „ 'I o s

111

I'l't-

n

H

6

< , ^ ^

H

0

]

•

1874.

h m s s

h m s

h in s

h m s

h in s

OltSEllVA-

2. 48. 27-0

+ 1 4-04

0. 48. 20-0

/

5. 23. 5ro

10. 56. ,10-0

+ 3. 27. 58-02

TOKY BAY,

/

b. 27. 20-5

1 1 . 5g. OO'O

+ 3. 27. 07-94

Dec. 1 5,

2. 49. 36-o

+ 1 4-00

5. 40. 1 5-o

m

5. 1 5. 3o-o

10.57. 3-0

-1-3. 27. 07-95

91'. to ioh.

m

6. 1 5. 5'o

u. 56. 48-0

+ 3. 27. 57-81

2. 49. 3g-o

+ 14-05

3.32. 6-0

n

3. 7. 20-0

10.58. 5'5

+ 3. 27. 07-59

n

4- 7- ' 7'°

n. 58. 12-0

+ 3. ?./. 57-69

OBSERVA-

3. 3o. 3o-o

+ 20-73

6. 22.3o-5

1

6. i. io-5

1 1. 41. 27-0

+ 3. 25. 0'23

TOKY BAY,

I

7. 1 5. 20-5

12. 55. 49-0

+ 3. 2J. 0-41

Dec. 17,

3. 32. 49-0

+ 20-74

6. i5. 3o-5

m

5. 49. 14-5

1 1. 38. 49-0

+ 3. 28. o-3g

q". to IOh.

m

7. 4. 6-0

i 2. 53. 53-0

+ 3. 28. o'2y

3. 35. 24-0

+ 20-7.5

4. q. io'o

n

3. 42. 5"o

1 1. 40. 35'o

+ 3. 28. 0-40

n

4. 56. 7'o

12. 54. 48-0

+ 3. 28. o'68

in s

MOLLOY

1 5. 43. 25-o

+ 6.22-54

6. 38. 40-5

I

5. 1 3. 5o-5

10. 55. 57-0

+ 3. 28. 46-59

POINT,

I

7. 12. 5-o

12. 54.31-0

4-3. 28. 46-53

Dec. 17,

1 5. 45. 10-0

+ 6. 22-60

6. 3i. 5'o

m

5. 7. 5o-o

10. 5q. 17-0

+3.28.46-77

2Oh. to 221'.

til

7. i.3o-o

12. 53. 16-0

+ 3. 28.46-66

15.47.37-0

+ 6. 22-67

4.24.42-0

n

2.54.30-0 10.54.47-0

+ 3. 28. 46-20

•ii. 4.54.33-0 12.55. 9-0

+ 3. 28.46-43

SDPPLY BAY,

23. 34. 37-0

a
— 52-62

2.22. 35'O /

o. 27. 6-5

6. 10. 24-0

+ 3. 27. 32-8g

Dec. 18,

/

2. 53. 3o-o

8.37. 12-0

+ 3. 27. 02-47

4'-. to 6".

23. 35. 1 5"o

— 52-62

2. 13. 52-0

m

o. 17. 1 5-5

6. g. 54-0

+ 3. 27. 3245o

in

2. 40. 5'O

8.38. S-o

+ 3. 27. 32-56

23. 36. io-5

—52-63

o. 6. o'o i it

10. 6. 38'o

o« 8. 4-*o

+ 3.27.32-82

11

o. 04. 16-0 ; 8. 36. 6"o

+ 3. 27.02-38

OHSKKVA-

3.58. 17-0

+ 20-84

6. 46. 2O'O

I

6. 8. 20-0

11.52.34-0

+ 3. 28. o-5g

TOUV BAY,

I

7. 21. 20-0

i. 5.46-0

+ 3. 28. o"5q

Due. 18.

3. 56. 38-o

+ 23-83

6. 35. 20-0

in

5. 58. o-o

1 1. 5i. 35 o

+ 3. 28. 0-62

g1'. to ii1'.

m.

7. 12. 40-5

i. 6.28-0

+3. 28. 0-54

3. 5q. 44*0

+ 23-84

4. 29. 40-0

ii

3. 48. 20-0 ii. 5o. 41-0

+ 3. 28. 0-24

11

5. i. 5ro i. 4. 23-o

+ 3. 28. 0-99

COMPARISONS OF SHIP'S CHRONOMETERS WITH CLOCKS AT THE
VARIOUS OBSERVATORIES.

469

kl

J, a .= .
•3-2-c o

921!

1* H

Time by the Portable Chronometer.

3 3
•BE

11

^

£ cc a

i- "^ *o

•

r-.~

_ —

5 ~r.

".§ =

-,.3.2 S.

H g d
^ •

- ^

3 __. j|*

O D

c —

..» fc

•£~ «5

'o a v
2> -° 3

3 § -1 ~

l!^l

'i i*
H.

ft 5 F'S- S "°
<- = 1 j 1 1

S| .

III

-^ -2

s ^ 5o

*" *y

_ O £•";

^ r. 01

11°

J If

2 r* — °

o

-'f C

is

^•|5 §

o.-s IS

SB a

55

H

o

•^

fc . <

5

0

. 1874.

h ni s s

1) m fl

h m s

h m 8

h m s

OBSERVA-

0.37. 18-0 +3o-oo

6. 17. 40-5

/

5.3i. 5-5

I I. 23. 4-0

+ 3.28. i-3q

TORY BAY,

/

6. 5o. 3o-5

o. 42. 42-0

+ 3.28. 1-37

Dec. 20,

3.36. i-O' +3o-oo 6. 6. 55-o

///

5. 24. o-5

II. 25. 28'0

+ 3.28. 1-37

gh. to lo1'.

///

6.42. 2O-5

o. 44. i -c

+ 3.28. i-3g

3.38.22-0 +29-99 ; 4. 0.47-0

II

3. 10. 37-0

II. 23. 33-5

+ 3. 28. 0-92

n

4. 32. o-o

o. 42. 9-0

+ 3. 28. 0-^9

m s

MOI.I.OY

20. 17. 3o-o +6.38-43 in. 0.27-0

I

9. 5o. 20-5

3. 45. 2-0

+3. 28.48-33

POINT,

I

o. 24. 5o-o

6. 19. 57-0

+3. 28. 48-39

Dec. 21,

20. 19.57-0 +6. 38-44

10. 53. 25'5c

m

9. 40. 3o'5

3. 44. 40-0

+3. 28. 48-37

i1'. to 4h.

m

o. 1 6. 40-5

6. 21. 16-0

+3. 28. 48-23

20. 23. 6-0 +6.38-46

8.48. 10-0

n

7.31. 5-o

3. 43. 38'5

+3. 28. 48-59

it

10. 9. 16-0

6. 22. i5'o

+ 3. 28. 48-49

s

OBSERVA-

3. n. 39-0 I +32-67

5. 48. io'5

I

5. 12. 25'O

ii. 8. 19-0

+ 3. 28. 1-20

TORY BAY.

I

6. 40. 1 1 -5

o. 36. 2o-o

+3. 28. -28

Dec. 21,

3. 9.47-0 +32-67 5. 36. 5o-o

m

5. 3. 55-o

u. 9. 1 8-0

+ 3.28. -21

8h. to ioh.

m

6. 34. 5'o

o. 09. 43-0

+3.28. -i5

3. io. 24-0 1 +32-67

3.32. "i-o

n.

2. 57. 3ro

u. n. 16-0

+ 3.28. -i3

n

4. 23. 5o-o

o. 07. 48-5

+3.28. -49

SUPPLY BAY,

i5. 52. 2a'o — 66'3o

6. 25. 40-0

I

5. 1 6. 40-5

u. 14. 34-0

+ 3.27.33-79

Dec. 21,

I

6. 53. 22-5

o. 5i. 32-o

+0.27.33-77

21h.t022h. 115.49.44-0

— 66-29

6. i3. oo-o

m

*5. i3. 20-0

u. 20. 44-0

+ 3.27.33-72

m

6. 46. 5o-5

o. 54. 3o-o

+3. 27. 33-74

1 5. 53. 5-o

— 66-3o 4. 8. 33-o

n

3. 1.40-0

II. 17. 2I'O

+ 3. 27.33-96

n

4. 37. 20-0

o. 53. 17-0

+ 3. 27.33-33

OHSKKVA-

I. 1 5. 33-o

+ 3g-63

3. 44. 35'5

I

3. 17. 5-o

9. 20. 35-o

+ 3. 28. 2'5g

TORY BAT,

I

4. 45. 35'5

10. 49. 20-0

+3.28. 2-71

Dec. 23,

i. 1 6. 44'o

+ 3g-63

3. 36. 1 5-o

m

3. 8. 2-5

9.21. 4-0

+3. 28. 2-45

6h. to 8h.

m

4. 35. 20-0

10.48.36-0

+3. 28. 2-40

i. 18. 25-5

+ 09-64

i. 29. 5o-o

n

i . o. 44-0

9. 21. 52'0

+ 3. 28. 2-46

'

n

2. 28. 42-0

10. 5o. 4-0

+ 3. 28. 2-61

OBSERVA-

4. 3.3o-o

+ -'9'47

6. 8. 54-0

1

5. 33. 3o-5

o. o. 53"o

+3.28. 7-18

TORY BAY,

1

6. 5o. 5-o

i. 17.40-0

+ 3. 28. 7-20

Dec. 29,

4. 6. 35-o + 59-48

6. 2. 5-5

in

5. 20. 40-0

u. 57. 55-c

+ 3. 28. 7-10

9h. to ioh.

m

6. 42. i5-5

1.19. 44'c

+ 3.28. 7-16

4. 8. o'o

+ 5g'48

3. 56. 1 5'o

11

3. 14. 20-0

1 1. 58. 5 re

+ 3.28. 6-78

n

4. 33. 5o-o

i . 1 8. 33-e

+3. 28. 7-48

Original j'1. 18"'. 20" -o.

470 TRANSIT OF VENUS, 1874. KERGUELEN ISLAND. ROFAL SOUND.

4]

tJ o +^ •"

' *22 '13 "£• **

S3 "1

•131
1 -at

a A
Time by the .Portable Chronometer, i

ll
j g

li

H^ cc s
a s

'-• « 'T!

EH <y es

P ' \ Hi ^ "e3 10

O.~i

6^

a .5

•~ -*

o

o> o 3
o-S-g 2

J1^ of

O 'r-> ^ P Ol

•r; a : 5 fcr "S S t.

_0 _oj

Nr£

4l

° 2 <u

o a .§ ^j

— a
0 «

^ a
•»!

« 3 - « 3
| » I? sj o

111

III

s ^^

gits!

fill

i! si

w*FO §O

jli

I'll

|l^

00

P

u

<! fc

<!

H

0

1874.

h m s

m a

h m s

h m 3

h m 3

h m s

BETSY COVE,

23. 5o. g-o

+ 3. 0-84

I. 43. 1 5'O

m

i. 3. 14-5

7. 43. 45-o

f3. 29. 22-70

Dec. 3o,

o. 1.26-0

+ 3. 5-83

i . 54. 3o-o >«

2. 5i. io'5

9.31.59-0

+ 3.29.22-74

4h. to nh.

23. 54. 8-0

+3. 5-84

1 1 . 40. o-o i M

10. 57. 42-0

7. 45. 21'0

+ 3. 29. 23-04

n

o. 44. 49-0

9. 32. 45-0

+ 3. 29. 23-i8

4. 33. 6-o

+ 3. 5-42

6. 35. io'o /

5. 1 8. 40-0

1 1 . 5o. 6-0

+ 3. 29. 22-89

I

7. 34. i o-o

2. 5. 58-o

+ 3. 29. 23-o8

4. 3o. 16-0

+ 3. 5-41

6. 22. 35-o

m

5. 7. 26-0

n. 48. 37-0

+ 3. 29. 22-g3

m

7.23. 5-5

2. 4.39-0

+ 3. 29. 22-96

4. 33. 42-0

+ 3. 0-40

4. 1 8. 04*0

n

3. 2. 3o-o

1 1. 5o. 48-0

+ 3. 29. 22-67

n

5. 1 8. 5-o

2. 6.45-0

+ 3. 29. 22-87

8

OBSERVA-

22. 43. 25'o

+ 6478

o. 41. 46-0

I

0. 2. 26-0

6. 36. 55-o

+ 3. 28. 8-34

TORY BAY,

I

i. i3. 10-5

7.47.51-0+3.28. 8-42

Dec. 3i,

22. 41. 58-o

+ 6478

o. 3o. 3o-5

m.

n.55. o-o

6. 3g. i8-o! + 3. 28. 8'3g

3h. to 5\

22.45. 2-5

+ 6478

10. 26. 35-o

m
n

i. 4. o-5
9.47. o-o

7.48.3o-o| + 3.28. 8-34
6.38.I7-5+3.28. 8-46

n

10. 58. i ro

7. 49. 40-0

+ 3. 28. 8-34

ERRORS and RATES of the SIDEREAL CHRONOMETER Z adopted by LIEUT. CORBET.

Approximate

Z Slow on Local

Local Mean

Time by Z.

Sidereal Time, as

Losing Kate ot'Z.

Solar Time.

adopted by Corbet.

At Observatory Bay.

d h

h m

h m 8

s

Dec. 1 5. 9

17. 10
, 18. 10

23. 28

o. 18

o. 28

+ 3. 27. 57-83
+ 3. 28. 0-40
+ 3. 28. o-5M

+ 1-25

+ 0-19

+ o-33

20. 10

o. 3

+ 3.28. 1-24

21. 9

23. 7
29. 10
3i. 4

23.54

22. 5

o. 3g

ig. 20

+ 3.28. 1-25

+ 3. 28. 2-54
+ 3. 28. 7-10
+ 3. 28. 8-38

+ O'OI

+ 0-67

+ 0-70
+ 0-69

At Supply l?ay.

Dec. 18. 5

ig. 23

+ 3. 27. 32'6o

21.21

12. 0

+ 3. 27. 33-72

ERRORS OF SHIP'S CHRONOMETER AND DIFFERENCES OF LONGITUDE. 471

Approximate
Local Mean
Solar Time.

Time by Z.

Z Slow on Local
Sidereal Time, as
adopted by Corbet.

Losing Rate
of Z.

At Molloy Point.

d h

Dec. 17.22

21. 3

h m

u.55

17. 6

h m s

+ 3. 28.46-54

-h 3. 28. 48-40

a

At Betsy Cove.

Dec. 3o. 8

22.47

+ 3. 29. 22-87

From the preceding tables the following differences of longitude were
inferred by Mr. Corbet:—

BETSY COVE

SI-ITLY BAY West of

MOLLOY POINT East of

East of

Chrono- OBSERVATORY BAY.

OBSERVATORY BAY.

OBSERVATORY

meter.

BAY.

December 17.

December zi.

December 17.

December si.

December 30.

8

8

B

a

m s

A

27-75

28-09

46-21

47'47

. i5-25

B

27-96

27-94

45-9l

47-08

. i5-og

C

27-8I

27-8I

46-06

47-27

. 15-17

D

27-97

27-88

45-92

47-26

• >4"94

E

27-88

27-84

46-01

47-32

. 14-85

F

27-66

27-29

46-47

47' 1 8

. i5-i6

G

27-99

27-66

46-02

47-11

. i5*3o

II

27-94

27-80

40-91

47-29

. 1 4-83

S

. .

t f

• '477

Z

27-96

27-87

46-06

47-16

. 1 5-og

/

28-34

45-66

. 4

m

28-10

27-90

46-07

47-36

i. 14-70

11

Means

27^0

27-79

46-06

47-26

i. i5-oi

+ 0-27 (rt)

+ 0-92 (a)

— 0-12 (a)

— 0-74(0)

- 3-86 (d)

- 2-01 (b)

— 2-5i (b)

+ o-g5 (c)

— O'2I (c)

— o-io (a)

26-16

26-22

46-89

46-3O

i . 1 1 -o5

Lieut. Corbet having used approximate errors of the transit-clocks at the
various stations, his longitudes have been corrected, (a) for Observatory Bay ;

3 P

472 TRANSIT OF VENUS, 1874. KERGUELEN ISLAND. ROYAL SOUND.

(Z>) Supply Bay ; (c) Molloy Point ; (d) Betsy Cove. The data for com-
puting these corrections are the adopted errors of the various clocks. For
Observatory Bay, see page 440 ; for Supply Bay, 457. For Molloy Point and
Betsy Cove Professor S. Newcomb and Dr. Auwers kindly communicate the

i/ *

following : —

Adopted Corrections to the Clock Hohwii 23,
at Betsy Cove, determined by observations —

Adopted Corrections

to Negus 1 53g, at

Molloy

Point, determined by

transit observations —

Sid. Time.

Neyu

s Slow.

Daily
Rate.

h

m

m

s

s

1874,

Dee. 12-5,
18-4,

4-

4-

547

3o-i

+ 0.

+ 6.

55-86
25-97

+ 5-o3

20
21

•5,
'4>

5.
4-

327

5o-4

+6.35-00
+ 6. 40-03

+5-i3

Sid. Time.

h

1874, Dec. 3o, o-o
4-5

Huhwii 23
Slow.

+ 3. I'QQ
JV

+ 3. i-5z

Hourly
Hate.

-
—O'lOO

Gr. L. T.

TRANSIT OF VENUS, 1874.

PART IV.

EXPEDITION TO KERGUELEN ISLAND

(continued).

Section 4.
OBSERVATIONS AT THUMB PEAK

By LIEUTENANT SOMERVILLE GOODRIDGE, R.N.

3? 2

474

CONTENTS.

PAGE

Establishment at Thumb Peak 475

Verification of Chronometer's steadiness 476

Goodridge's Observations of the Transit ..> 476

Reference of times to Transit-Clock. Observatory Bay . ^ . . . . p ." 478

Equations deduced from the Observations -^ . ' . 479

'•I £ '• ' ' :

, -• •

475

ESTABLISHMENT AT THUMB PEAK.

On the morning of 1874, December 7, civil reckoning, Lieut. Somerville
Goodridge, R.N., accompanied by the Rev. A. B. Eaton (Naturalist of the
Expedition) and servants, proceeded in the Supply from Observatory Bay
towards Thumb Peak, and selected a spot at which the observation of the
transit could be made. The party then went in the Supply to the anchorage
at Three Islands Harbour, for the night ; and returned early in the morning
of December 8 to the selected spot, and prepared for the observation. They
encamped there for the night.

The locality is fixed by the following bearings : —

S.E. part of Thumb Peak, S. 75°. 20'. W.
S.E. point of Sughin Island, N. 19°. 20'. E.
S.E. point of Sharban Island, S. 62°. 00'. E.

It is believed that these bearings are magnetic, uncorrected for Magnetic
Variation.

For determination of the co-ordinates of the station in the usual form,
Mr. Perry, on December 13, four days after the Transit, proceeded in the
Supply to Thumb Peak, carrying with him De la Rue's Altazimuth and a
sidereal chronometer called S, and returning on December 21. On a small
hill, 215 feet high, near Lieut. Goodridge's station, a pile of stones was built
for the altazimuth, and a tent placed over it. Mr. Perry observed stars near
the meridian for latitude, and Sun and stars in other positions for chrono-
meter-error. The chronometer was compared with Z of the Supply when she
made the rounds mentioned in the last section ; and from these comparisons,
and those made before starting and after returning, the relation of its times
to the local times at Observatory Bay was found. It will be seen shortly
that no extreme accuracy is required in this process ; and I have therefore
thought it unnecessary to exhibit all the details. The result was, that the
latitude of the station is 49°. 31'. 11". South, and that in longitude the station
is lm. 7S'7 East of Observatory Bay, or 4h. 40'". 4P-2 East of Greenwich.

The telescope used by Lieut. Goodridge is an achromatic by Dollond, of
3^r inches aperture and 46 inches focal length, on a firm tripod stand, with
horizontal and vertical movements ; lent from the Cambridge Observatory.
It was not fitted with a diagonal reflector for feeble reflection of the Sun's
rays ; dark glasses were screwed on the eye-hole as required.

476 TRANSIT OF VENUS, 1874. KERGUELEN ISLAND. THUMB PEAK.

Time was taken from the solar chronometer Fletcher 950, of which the
dial was limited to 12 hours. The observations were recorded, from Lieut.
Groodridge's words, by Mr. Baton. Before leaving the Supply on December 7,
Fletcher 950 was compared with the solar chronometer Cribb 725 (the ship's
chronometer) ; and on returning to the ship it was again compared. The
object of these comparisons was merely to obtain assurance that Fletcher 950
had not received injury in landing from the ship and returning to it. They
are as follows : —

hras h m a hms

Deo. 7 (civil) Fletcher g5o, 1 1. i. 20-0= Cribb 720, 5. 48. i3'5 : Excess of Fletcher g5o, 5. i3. I r">

n. 4.00-0 5. 01.38'") 5. «3. ii'5

8. 3g. 5o 3.26.35 5. i3. u>

8.44.40 3.3i.2o 5. i3. i5

Dec. 9, Fletcher 960, 7. 53. 34 2. 40. 10 5. i3. 24

7-35-29 2.42. 5 5.13.24

2. 52. 26 9. 3g. o-5 5. i3. 25'5

2.04.31 9-41- 5-5 5. i3. 25'5
The result appears to be satisfactory.

LIEUTENANT GTOODRIDGE'S REPORT ON THE OBSERVATION, OF THE TRANSIT.
The following remarks were written by me after the Transit, whilst the
gear was being taken on board. [They are slight extensions of the notes
written by Mr. Eaton.] The power used was 121. The times are taken from
the chronometer Fletcher 950 : —

Ingress.

hms

7. 7.45-0,1 f I observed the planet's limb to be complete, and much illuminated at the outer
or Dec. 8, > < or lower edge; this was not the time of tirst appearance but some seconds
19. 7. 45-0. J (• after it.

g f Apparently geometrical contact ; but as the light improved after I had given the

or Dec. 8 > J sionul» I found I was early ; and fearing to lose the time of the more important

8 10-7 J I phenomena by calling the time- taker's attention away and running it too close, I

8 10-7

^ let the better one pass. I should say it w;is about 4s later.

3 46-0 i f^ °bserved a considerable difference of light in the black drop ; but the light being
or Dec. 8 > J very clla"oeil!)le> and no appearance of n distortion such as the model produced
iq. 8. 46-0. J I °n a b"ont d»y» I cannot think it was the same alteration of light or phenomena
L as was known to me as No, 2 of the four to be observed.

•j. 9. o'o, -.
or Dec. 8, >
19. 9 5-0. J

o-o -. is time was the instant before the cusps actually joined, the light being scarcely

I visible between them. There was no sudden connection, but a steady and
regular meeting of the cusps. Although the light was dull, it was light com-
pared to the other phenomena.

GOODRIDGE'S OBSERVATION OF THE TRANSIT. 477

b

7. 9.27-00 r At this time a rather broad band of light was complete between the two bodies ;
or Dec. 8, > < but still a dark shadow was visible behind. The definition was not good, orf
19. 9. 27-0. J L account of the boiling of the limb*.

7- 9-497,-j

or Dec. 8, > All appearance of shadow totally disappeared just before this.
19. 9. 497 J

Egress.

JO. 3o. io'o, -]

or Dec. 8, > At this time a few lines or slight shadow appeared between the two limbs.
22. 3o. io'5. J

, C At this time the shadow gradually darkened, until the black drop assumed a

10. 3o. 24*0, -.

T) 8 U solid appearance of the same density as the planet. Unfortunately a dark

f j cloud came over, and I lost all further views until just before total disappear-

22. 3o. 24'o.J I J

[__ ance.

11. 2. 9'5, -j

or Dec. 8, > There was just sufficient light to see it.

23. 2. 9-6. J

Having no wedge, I found great difficulty in observing the several phenomena,

the light being so variable, and being unable to change the shades to suit the
different lights makes me a little uncertain whether some of the times I took
were only due to change of light or actual phenomena.

TIMES OF PHENOMENA OBSERVED AT THUMB PEAK.

I have ascertained that, by due attention to the various changes in
chronometers and clocks, with assumption of an error of one hour in Fletcher
950 on December 10, the comparisons harmonize perfectly. They stand
thus —

Fletcher 950. Transit-Clock. Proportion of Intervals.

(1 h m s li m s

1874, December 4. 2. 8.17-0 = 18. 5g. 53'o

roo2oo2
6. 2i.o3. 4'o = 14.30.26-0

1-002660

10. l.I2.02'0 = l8.27. l8'O

1-002662

11. 6. M. 29-0 = 23. 04. 37*0

In the following calculations we want only the second and third com-
parisons.

We are now to calculate the Transit-Clock Times (which relate to the
Transit-Clock at Observatory Bay), the Sidereal Times for Observatory Bay,
and the Sidereal Times for Greenwich, for each of the nine phenomena. The
proportion of successive intervals of chronometer to corresponding intervals
of Transit-Clock = 1 -000000 : 1-002660.

478 TRANSIT OF VENUS, 1874. KERGUELEN ISLAND. THUMB PEAK.

Subject of
Observation.

Fletcher 950.

Successive Intervals.

Successive Intervals
for
Transit-Clock.

Transit-Clock;

d h m s

h m s

h m s

h m s

Second comparison

6.21.33. 4'5

14. 35. 26-0

40. 34. 40*0

45. 41. 56-g

(=164080-5)

(=164516-9)

1st phenomenon

8. 19. 7. 45-0

(=6.67. 7.45-0)

12. 17. 22-9

34-7

34'8

2nd phenomenon

8. 19. 8. 19-7

12. I7.57-7

26-3

26-4

3rd phenomenon

8. iq. 8. 46-0

12. 18. 24-1

19-0

19-0

4th phenomenon

8. 19. 9. 5'0

12. 18. 43-1

22-0

22'1

5th phenomenon

8. ig. g. 27-0

12. ig. 5'2

227

22-8

6th phenomenon

8.19. 9.497

12. ig. 28-0

3. 20. 20-8

3. 20. 527

,

(=I202O'8)

(= 12002-7)

7th phenomenon

8. 22. 3o. io-5

1 5. 40. 20-7

i3'5

i3'5

8tU phenomenon

8. 22. OO. 24-0

1 5. 40. 34-2

3i. 45-5

3i. 5o"5

(= igoD-5)

(= igio'5)

gth phenomenon

8. 23. 2. g-5

l6. 12. 24-7

26. 10. 42*0

26. 14. 53" i

(=94242-5)

(=94493'0

Third comparison

IO. I. 12. O2'O

8 (i7"81

( = 8.49. 12.52-0)

1.8-o.T

It will be remarked that the record of times in the last column does not in
any way depend on the longitude of Thumb Peak, being directly referred to
the Transit-Clock at Observatory Bay. The absolute times of the phenomena
depend in a very slight degree on the geographical co-ordinates of Thumb
Peak.

The corrections to the Transit-Clock (below) are interpolated from those in
Part IV., Section 1, Tables IV. and V.

The Greenwich Sidereal Times, which are required for interpolation of
tabular places of Sun and Venus, are formed by subtracting from the Obser-
vatory Bay Sidereal Times the value, 4h. 39m. 338'5, of the eastern longitude
of Observatory Bay,

The Thumb Peak Sidereal Time, which is required for computing the
factor of parallax, is formed by adding lm. 79'7, the longitude of Thumb
Peak East of Observatory Bay, to the Observatory Bay Sidereal Time.

EQUATIONS FROM GOODRIDGE'S OBSERVATIONS OF THE TRANSIT.

479

Clock Time
for
Correction.

Correction to
Transit-Clock.

Observatory Bay
Sidereal Time.

Greenwich
Sidereal Time.

Thumb Peak
Sidereal Time.

Local Tabular
Distances of
Centers of Sun
and Venus.

h m

6. 42

3

+ 52-32

h m s

12. 18. l6'0
12. 1 8. 5o'8
12. ig. 17-2
12. ig. 36'2

12. 19. 58-3

12. 2O. 2I'I

h m s

7.38.42-5
7.3g. I7-3

7- -5g. 43-7
7.40. 27
7. 40. 24-8
7. 40. 47-6

b m s

12. ig. 23'7
12. ig. 58'5
12. 2O. 24-9
12. 2O. 43-9
12. 21. 6-0
12. 21. 28-8

/ //
15.40-57

12. 18

+ 53-07

i5. 40

+ 53-52

i5. 41. 14-2

10.41.27-7

n. 1.40-7
11. 1.54-2

15.42. 2I'q
1 5. 42. 35*4

1 5. 5ro3

1 6. 12

+ 53-6 1

16. i3. i8-3

u. 33.44-8

16. 14. 26-0

....

3.58

+ 58-39

Taking R = 976"'80, r — 31"'42, at Ingress, and R = 976"-82,
r = 31"'42, at Egress, and mean solar parallax = 8"'950 X fl + — ),
we have —

For 2nd phenomenon, " Apparently Geometrical Contact"

+ 4"-8i = +o"-2i52 n +-6020 8 E.A. —7577 8 N.P.D. — o"-

and for 8th phenomenon, " Black drop assumed a solid appearance "—
+ 4"-37 = +O"MOIO n —'1957 8 R.A. —'9773 S N.P.D. +o"-o3i7 8 t — S R + 8 r.

3 Q

TRANSIT OF VENUS, 1874.

PART V.

EXPEDITION TO NEW ZEALAND,

UNDER

MAJOR H. S. PALMER,

ROYAI, ENGINEERS.

3Q 2

482

CONTENTS.

I'AOK

Voyage, and Names of Observers 483

Site at Burnham 483

Connexion with the Telegraph 484

Arrangements for observations at five additional stations, and general failure 484

Location of the Instruments at Burnham 485

The Transit-Clock 485

The Transit Instrument 485

Micrometer Screw and Intervals of Wires 486

Zero of Collimation 486

Error of Level 486

Error of Azimuth 487

Meridian Mark 487

Transits of Stars and the Moon . . 488

The Altazimuth Instrument 489

Vertical Circle and Micrometer Runs 490

Latitude of Burnham 491

Observations of Azimuth 491

Results for the Longitude of Burnham 493

Observation of the Ingress of Venus by Major Palmer 493

Micrometer Measures of the Distance of Limbs 496

Equations deduced from the observation 01 Ingress 497

OBSERVATIONS IN TABULAR ARRANGEMENT :

Table I. — Collimation of the Transit Instrument ....'.... 500

Table II. — Error of Level of the Transit Instrument 501

Table III. — Azimuthal Error of the Transit Instrument 504

Tables IV. and V. (Abstract) — Transits of Stars and the Moon, and Inferred

R.A. of the Moon's Limb at Transit 508

Table VI. — Longitude of Burnham, from the Meridional Transits of the Moon 512

Table VII. — Longitude of Burnham, from the observed Azimuths of the Moon 512

ESTABLISHMENT AT BURNHAM. 483

VOYAGE, AND NAMES OF OBSERVERS.

MAJOR PALMER, R.E., accompanied by Lieutenant H. CraAvford, R.N., as
Assistant in the Astronomical Department, and by gentlemen whose duties
were limited to the Photographic Department, sailed from Plymouth in the
sailing ship Merope on 1874, June 27, and arrived at Port Lyttelton on
September 27. The time of the voyage was employed in preparing various
numerical computations, by which much trouble was subsequently saved.

THE SITE AT BURNHAM.

Major Palmer proceeded immediately to examine the country in the
neighbourhood of Christchurch, for selection of a site for the Transit Obser-
vatory. In this he was assisted in every way by His Honour "W. Rolleston
and other resident officials. After balancing various considerations, Major
PALMER fixed on BURNHAM, a place about 18 miles distant from Christchurch r
and on the Southern Railway ; and he states that subsequent experience gave
him no reason to repent this choice. The only drawbacks to Burnham were
the wind and the frequent mirage, which gave some little trouble, but nothing
serious.

A railway, accompanied by telegraph, runs through the whole length of
the great southern island of New Zealand. The plot of ground selected for
the Observatory is described by Major Palmer as 800 yards N.W. of the
Burnham Railway Station, and 360 yards in rear of the Industrial School, on
land belonging to the Provincial Government ; and here a quadrangular space
about 180 x 133 feet was inclosed. Major Palmer satisfied himself by
experiment that no sensible tremor was communicated to the Observatory
ground by the passage of the heaviest trains on the railway. All the
instruments were in place on October 30. For avoiding the possible effects
of mirage the equatoreal pier and hut were raised 3 feet higher than would
otherwise have been necessary. The works generally were effected by the
local Government, who voluntarily undertook this expense.

484 TRANSIT OF VENUS,' 1874. NEW ZEALAND. BURNHAM.

CONNEXION OF THE ASTRONOMICAL STATION WITH THE TELEGRAPH.

Omitting many points of arrangement, one which is most important
requires to be noticed. "Wires were led from the Burnham telegraph office
to the Observatory station, and thus the Observatory was placed in com-
munication with every part of the islands at which co-operation in observation
could be expected, and also with the American Observatory at Queenstown.
Major Palmer also states that he was enabled to measure differences of
longitude with Queenstown, Dunedin, Wellington, and Auckland, and to give
time to the French war ship Vire, thus making connexion with the French
transit party at Campbell Island.

ARRANGEMENTS FOR OBSERVATIONS AT FIVE ADDITIONAL STATIONS, AND

GENERAL FAILURE.

Major Palmer finally made the following arrangements for observation at
multiple stations: — Lieutenant Crawford was despatched to Naseby, in
Otago, to establish a complete observatory. (I believe it was owing to this
circumstance that the number of altazimuth-observations for longitude at
Burnham is smaller than I had expected.) Stations at Grahamstown,
Auckland, Wellington, and Dunedin were manned by private residents,
Mr. H. A. Severn, Mr. T. Heale, Archdeacon Stock with Dr. Hector,* and
Mr. J. J. Thomson with Mr. J. Mackerrow ; who placed themselves under
the orders of Major Palmer, and used instruments their private property.
This line of stations extended over 750 miles.

Assistance was given at the Burnham Observatory by Lieutenant Herbert
Praed, E.N.

Among many detailed preparations for the transit, one was the issue of a
circular to the owners and occupiers of land within a radius of three miles
from Burnham, requesting them to guard against burning grass after
December 1, and to keep a watch against fire on the days near December 9.
These requests received universal compliance.

The preparations appear to have been very complete.

Unfortunately, the state of the weather caused an almost total failure.
At Burnham the partially-imperfect observations to be detailed hereafter
were made, but not a single observation was made at the other stations.

Allusion is made by Major Palmer to telegraphic time-signals with the
American observers at Queenstown, but I am not aware that there is any
detail of them in the papers which have reached me. [G. B. A.]

INSTRUMENTS AT BURNHAM. 485

i
LOCATION OF THE INSTRUMENTS AT BURNHAM.

The Altazimuth was 30 feet north and 65 feet east of the Transit ; the
6-inch Equatorial was 85 feet north and 37 feet east of the Transit ; the
Photoheliograph was 50 feet north and 25 feet west of the same instrument.
The instrument piers (of bricks laid in cement) rested on concrete founda-
tions, at depths 4 ft. 6 in. to 5 ft. 6 in. below the level of the ground. The
model, artificially representing the phenomena of the Transit of Venus, was
erected 400 feet from the Equatorial, on the bearing S. 60° E. The meridian
mark for the Transit was distant 6054 feet, and was found to be 4"'65 East
of South.

THE TRANSIT CLOCK,

originally made by Arnold for use at the Koyal Observatory, was placed in
the hands of Messrs. E. Dent and Co. in 1871, and was fitted with their
cylindrical zinc-and-steel-pendulum, the compensation of which was severely
tested at the Royal Observatory. - It was suspended on a solid tripod stand
of wood, which stood upon stakes driven deeply into the ground through
apertures in the floor of the transit observatory.

The performance of the clock was, generally speaking, indifferent, though
it happened to be going pretty well about the time of the transit. Although
the tripod-legs were perfectly isolated from the floor of the hut when it was
put up, it was found on dismantling the hut (January 14) that there was contact
at one point between a leg of the tripod and the underneath part of the
flooring, which must have been caused by settlement of the hut ; and, if this
happened in the early part of our stay, it might account for the irregularity
of the rate. There was always much traffic about the clock, as the telegraph
instruments were inside the hut. [See Abstract of Tables IV. and V.]

THE TRANSIT INSTRUMENT.

The Transit instrument, its piers, the hanging level, and the wooden
observatory were in every respect similar to those used at Honolulu (pp. 9
et seq.)

The Equatorial intervals of the ^vires were found by bringing each wire in
succession into coincidence with the image of the meridian mark by means

486 TRANSIT OF VENUS, 1874. NEW ZEALAND. BURVHAM.

of the micrometer-screw, taking the value of one revolution of this latter at
56"-40, as follows :—

October 28. November TO. December 4.

Wire I + 427 '9 +428-1 + 428-0

,, II + 2i5-g + 2i5'7 +210-6

,, III + 0-9 + 0-8 + 0-8

,, IV —210-4 — 215-4 — 2i5-o

,, V —429-1 —429-3 —429-4

The wires are numbered in the order in which a star above the pole will
cross them with the micrometer Bast. The reduction from the mean to the

middle wire is therefore — 0"'9 X 1 5' sin N.P.D.* which has been taken =
— O06 for stars within 30° of the Equator.

The value of one revolution of the micrometer-screw was determined on
25 nights from close circumpolar stars, the mean value being 56"-40.

The Gollimation of the center wire was found for the first few nights by
reversal on polar stars ; it was not steady. The meridian mark was then
used. Finding the readings irregular, the screws about the wire frame were
, carefully examined (on November 5), when two of them were found1 to be a
little loose. This was rectified, and the collimation at the same time adjusted
nearly to zero (20r'000). After this it was satisfactory. The collimation was
occasionally determined by means of a small reversed telescope mounted on a
pier about 12 feet on the north side of the instrument. It will be sufficient
to state here that, when observing stars for time, the reading of the micz-o-
meter-head was always kept at 20r'000 throughout the whole series. [See
Table I.]

The Error of Level of the transit axis was always determined with the
hanging spirit-level. The graduation of the glass bubble was re-examined
before the Expedition left England, when 30 divisions were found equal to
one minute of arc, which value has been used throughout. On October 28
the value of the level graduation was tested by means of the Bohnenberger
eye-piece and the known value of the micrometer-screw. One division was
found equal to 2"'005. The level-error was steady, and was kept small by
adjustment when necessary. It seldom exceeded 5". The usual course was
to apply the level at the beginning and end of each night's observations,
before and after polar stars, before and after the Moon's transit, and
generally at intervals of about an hour while observing. For the reduction

TRANSIT INSTRUMENT. 487

of the transits a level-error was obtained for each, star, or group of stars, by
combining the several determinations. [See Table II.]

The correction to the level-error for inequality of the size of the pivots
was found on 1874, October 28, November 24, and December 3, to be
— 0"-05, — 0"-15, and — 0"-10 respectively, the sign referring to " Micrometer
East." The value — 0"'05 was used up to November 23, — 0"-15 to
December 2, and — 0"'10 on and after December 3.

The Error of Azimuth was determined from observations of the 8 close
southern circumpolar stars in Mr. Stone's list, 1874, February 28 (see
Eodriguez Observations, page 356). No other stars were used. On six
occasions the error of azimuth was obtained from the Meridian Mark,
assuming this latter to be 4"'65 Bast of true South. The changes of the
azimuthal position, if at times somewhat rapid, were pretty regular in one
direction during the first three weeks of November, namely, in that direction
which would correspond with a southerly movement of the east pier. After
this there were two or three sudden changes, from time to time, connected
apparently with heavy rain-fall, but no further steady progressive movement
in one direction. Rain seemed to act immediately on the azimuth without
affecting the level. The azimuth error was reduced by the adjusting screws
on November 2, 18, and December 10 ; on October 27 it was disturbed by
touching the level adjustment. [See Table III.]

The Meridian Mark was erected October 26, about 6054 feet south of the
Transit instrument. It consisted of a small brick pier, about 2 feet square
and 7 feet high, to the north face of which was cemented an iron plate 2 feet
6 inches long, and 1 foot 6 inches broad, with top and bottom flanges entering
5 or 6 inches into the brickwork. The face of the plate was painted black,
with a diagonal cross of white lines half an inch wide. At the exact center
of this cross a circular hole one-third of an inch in diameter was drilled
through the plate, and behind it a chamber was left in the pier sufficiently
large to hold a railway signal lamp, which was trimmed and lighted at dusk
every night and which would burn for six hours. The zenith distance of the
mark as measured by the transit instrument was 90°. 15'. At night, when
illuminated, it appeared like a star of the fifth or sixth magnitude. It has
not been removed. The iron plate was shifted 3^ inches to the Bast
on October 28.

The following are the determinations of the absolute azimuth of tilt-
meridian mark, obtained by comparing the observations of it when illumi-

3 B

488

TRANSIT OF VENUS, 1874. NEW ZEALAND. BURNHAM.

nated at night with those of the close circumpolar stars observed for azimuth
error : —

Mark East
of South.

874, October 28
3o

3'9

November 2

2'2

3

7-2

7
8

4'7
1-6

12

7'3

i5

1-8

18

5'9

20
21

7-0
5-6

23

4-5

27

4'4

29

3o
December i

4-8
4'4

5'2

Mark East
of South.

1874, December

1876, January

2

3-2

3

2'O

6

4'9

IO

9' !

18

5-o

19

4'3

26

4-5

27

4-0

28

4'4

29

6-7

5

4'9

9

3-4

ii

8-7

12

3-5

io

4' I

The adopted position of the meridian mark is 4"'65 East of South.

The observations of the mark are entered in Table III. ; each micrometer
reading there given represents the mean of five or more bisections of the
mark, generally when illuminated at night.

TRANSITS OF STARS AND OF THE MOON OBSERVED AT BURNHAM.
(Abstract of Tables IV. atul V.}

The transits of stars observed on all days when the Moon was also observed,
either with the Transit instrument or with the Altazimuth, are given in the
same detail as for other stations. The observations were completely reduced
by Major Palmer.

The transit-micrometer was kept at 20r-000 for all clock stars, and the
bisections of circumpolar stars with the center wire were so taken that the
mean micrometer-reading was 20r>000.

For the Moon, the transit was corrected in the same manner as a transit of
a star. A correction was then applied for the Moon's motion, which was
obtained by multiplying the sum of the instrumental corrections by the
Moon's motion in R.A. in one second of longitude.

TRANSIT OBSERVATIONS. THE ALTAZIMUTH. 489

THE ALTAZIMUTH INSTRUMENT AND OBSERVATIONS.

The Altazimuth used at Burnhain was made by Messrs. Troughton and
Simms about the year 1864 for the Royal Observatory. It has two vertical
and one horizontal circles of 15 inches diameter, divided to 5', each read by
four micrometer-microscopes. The object-glass is of 2| inches diameter and
27 inches focal length. The telescope and horizontal axis are constructed to
give what is known as the axis-view. A rectangular prism of total reflexion
is placed at the point of intersection of the optic axis of the object-glass with
the horizontal axis, so as to reflect the cone of light formed by the object-
glass horizontally into one of the pivots to which the eye-piece and reticule
are fitted. The weight of the half-telescope carrying the object-gass is
counterpoised. The illumination of the field of view is effected by lamp-light
passing through the opposite pivot and through the center of the prism
mentioned above, a very small rectangular prism being cemented to the center
of the inclined face of the larger prism, and, therefore, exactly in the line of
pivots, to allow the light to pass through. There are five vertical and five
horizontal wires, the latter having larger intervals than the former.

The microscopes of the horizontal circle are supported by radial arms cast
in one with the rotating body of the instrument, and are perfectly rigid.
There are two zenith-distance levels and two levels attached to the horizontal
circle. A striding level, similar to those used with Transit instruments, is
used for determining the inclination of the axis. The value of the divisions
of this level were tested before leaving England, when 50 divisions were
found equal to one minute of arc, which was the former value.

On unpacking the instrument at Burnham, one of the pivots, which were
of hard white steel, was found to be badly rusted, apparently from a piece of
paper having been wrapped round it; for the other pivot, without paper, was
quite bright. A small spider had been at work among the webs of , the
reticule, but without doing any real injury to them. The pivot having been
cleaned as well as possible, the instrument was mounted, on October 16, on a
pier of masonry.

The inequality of the pivots of the horizontal axis was approximately
determined on December 11. The level error was determined five times with
the axis in each position ; the resulting correction to the level error found
by the striding level, 0"'62, positive with " lamp right," has been applied
throughout.

SR 2

490

TRANSIT OF VENUS, 1874. NEW ZEALAND. BURNHAM.

The horizontal intervals of the vertical wires were found on December 21,
by means of the transit meridian-mark before described. Ten bisections of
the mark were made with each wire (five in each position of the instrument),
the horizontal circle being read each time. There being no imperfect hori-
zontal transits observed, the intervals are only required in order that the
distance of the mean wire from the center wire may be known.

The following are the circle-readings corrected for runs : —

Wire.

Circle-reading, Lamp Left.

Circle-reading, Lamp Right.

I

O 1 II

IO4.. 5. IQ'C)5

o / //

283.53. 7*75

II

104. i. 4i-85

283. 56 45-50

Ill

io3. 58. q'85

28it. O 17'J.Q

IV

io3. 54. 46*80

284. 3. 4i-85

V

io3. 5i. iS'go

284. 7. io'83

Mean

io3. 58. 14*87

284. o. 1 2*68

The wires are numbered as seen from left to right with lamp left. The
circle-reading for the mean wire has been taken as 4"'92 greater than for the
center wire with lamp left.

The corrections for runs of micrometers of the horizontal circle were found
as below. Each determination is the mean of four or six at different parts
of the circle, made usually on the morning after a night's work.

Day.

Observer.

Correction for Runs for 100".

1874.

//

October

23

C

— o-3g

27

D

- o-38

28

C

— 0-44

November

i5

D

— 0-43

'9

C

— 0-46

20

D

— o-3o

December

28

D

- o-38

The vertical circle of the Altazimuth is 15 inches in diameter, read by four
micrometer-microscopes, which are attached by binding-thumb-screws to a
movable flat ring of bronze, which is screwed at four points to arms projecting
from the frame of the instrument ; a form of mounting which, in Captain
Tupman's opinion, is not conducive to the steadiness of the microscopes, or to
their easy adjustment.

LATITUDE, AND OBSERVATIONS OF AZIMUTH.

491

The corrections for runs of the microscope-micrometers, for an arc of 100",
are as follows. They are the means of determinations at four or six different
parts of the circle.

Day.

Observer.

Correction for Runs for i oo".

1874.
October

22

p

//
— 0-28

23

C

— o-43

2?

3i

D

C

— O'4I

— o-3o

November

10

D

— 0-48

'9

C

— o'4i

1870.
January

7

12

C
C

— o'35
— 0*46

LATITUDE OF BURNHAM.

Observations of zenith distance of 28 stars were taken with face of the
vertical circle alternately east and west, and all corrections proper for such
observations were applied. The North Polar Distances of the stars were
taken, as far as possible, from the Greenwich Catalogue of 2260 Stars for
1864. For stars near the South Pole the polar distances were taken from the
Cape Catalogue 1860, and the Melbourne Catalogue 1870. The results were
as follows : —

Co-latitude of Burnham —

o / //

By 19 stars North of the Zenith 46. 23. I i'5g

9 stars South of the Zenith 46. 23. 1 2'i5

o / //

Adopted Co-latitude .... 46. 23. 1 1 '9

, , Latitude 43. 36. 48' i South.

OBSERVATIONS OF AZIMUTH WITH THE ALTAZIMUTH.

In making an observation, the instrument is clamped in azimuth, and the
zenith-distance slow-motion is used to make the transit of the object take
place over the middle of each vertical wire. The striding level is applied in
both positions to determine the error of level, after the four microscopes of
the horizontal circle have been read. The instrument is then reversed,
another transit observed in a similar manner, the circle read, and the level

492 TRANSIT OF VENUS, 1874. NEW ZEALAND. BURNHAM.

error again determined with the striding level, thus completing one
observation.

Every observation of the Moon is accompanied by one of a star as near
the Moon as possible. The error of collimation and zero of azimuth are
deduced from the observations of the stars. The error of collimation is not
required to be known with great accuracy, but as this is an instrumental
quantity which cannot be subject to great changes, its determinations afford
a test of the general accuracy of the observations. The zero of azimuth will
of course be affected by any error that may exist in the local time obtained
by another observer with the Transit instrument and transferred to the
Altazimuth Clock ; but the adoption of the observed zero of azimuth on each
night practically makes the observations differential.

To the mean of the clock times of transit over the five vertical wires, the
clock correction is to be applied ; it is taken from the Abstract of Tables IV.
and V. Then putting I for the error of level of the horizontal axis determined
by the striding spirit-level, the correction to the circle-reading for error of
level is —

+ 1. cot Z.D.

The correction for error of collimation (c) is —

-f- c.cosec Z.D.

By applying the zero of azimuth to the circle reading thus corrected, the
observed azimuth is obtained. The approximate apparent zenith distance is
then computed.

The Greenwich Mean Solar Time corresponding to the local sidereal time
of each observation is then found on two assumptions of longitude, viz.,
llh. 29m. 0s. and llh. 30m. 0s. East of Greenwich. The Apparent Eight
Ascension and North Polar Distance of the Moon's center are then inter-
polated with second differences from the hourly ephemeris in the Nautical
Almanac, and corrected for errors of the tables by the quantities given in
the Appendix. The semidiameter is also interpolated from the Nautical
Almanac.

With the local sidereal time of observation and each of these sets of
elements, and with the latitude already found, the tabular azimuth of the
limb has been computed by the Normal-centric method, which is explained
and all the formulas given in the Introductions to recent volumes of the
Greenwich Observations. If the two tabular azimuths corresponding to the
one local time be nearly identical, the position of the Moon was not favour-
able, and the observation is of no value ; but if there be a difference con-

LONGITUDE. OBSERVATIONS OF INGRESS. 493

giderably greater than the degree of accuracy with which the instrument is
capable of measuring azimuths, the true longitude can be inferred by a
simple proportion. Of all methods of obtaining the longitude by means of
the Moon's motion, that of observed azimuths is the most troublesome. [It
is, however, used successfully at Kerguelen and at Burnham, as far as the
number of observations permits. — G. B. A.]

[For the same reasons as in the similar stages of operations in Part III.
and Part IV., I have suppressed the details of the Altazimuth Reductions in
this Part.— G. B. A.]

Table VII. contains the mean result for longitudes of Burnham, inferred
from the observations of each day exhibited separately for the preceding and
following limbs of the Moon.

ON THE LONGITUDE OF BURNHAM.

The Meridional Transits of the Moon, Table VI., give IP. 29m. 10S'6.
The Observed Azimuths, Table VII., give IP. 29m. 20s-5.
The latter observations are less numerous, and probably inferior in quality.
If we give weights to the results in the proportion of 3 : 1, we shall obtain for
final longitude of Burnham —

IP. 29m. 13S-1 East.

OBSERVATIONS OF THE INGRESS OF VENUS, 1874, DECEMBER 8 (GREENWICH
RECKONING), DECEMBER 9 (NEW ZEALAND RECKONING).

After describing the preparations for observation, and the unfavorable
character of the weather preceding the Ingress, Major Palmer proceeds as
follows : —

Thelirst glimpse after first contact was obtained at 18h. 41m. 36S>25 sidereal ;
the planet was then seen to have advanced apparently about three-eighths of
her diameter on the Sun. Both Sun and planet could only be just made out
through the clouds, without any coloured shade to the eye-piece. Having
adjusted to center of field, I now exchanged the eye-piece for the double-
image micrometer, and between this and 18h. 54m. made a dozen attempts
to effect measures of diameters and cusps, in the few brief glimpses (never
exceeding 8 to 10 seconds) which were now and then afforded by partial rifts
in the dense masses of cloud. My efforts, however, were quite unavailing.

494 TRANSIT OF VENUS, 1874. NEW ZEALAND. BUKNHAM.

Besides the loss of the already faint light, which rendered the images
scarcely discernible, before adjustment for position and equal brightness of
images could be made the Sun was gone from view. This happened at each
re-appearance ; there was never time (generally the -appearances lasted but
four or five seconds) to adjust for an accurate measure in the middle of the
field, even had such measures been possible with the imperfect light — still
less to make a measure. I am certain, moreover, that even had the light
remained steady at its maximum brightness, it was too dim, and the clouds
were moving too quickly and confusingly across the Sun, for any measures
of value to have been secured. I was quite cool, and prepared to make the
most of every opportunity.

The whole time before internal contact 1 never used a coloured glass, and had
difficulty in snaking out the Sun without one.

At 18h. 49m. 2P-26 sidereal the cusps subtended about 95°. at planet's
center, as estimated in a passing glimpse.

At 18h. 53m. 6S>26 sidereal another glimpse showed cusps about three-fifths
of a diameter apart — pretty sharp. An ordinary eye-piece was now inserted.
In glimpses —

h m s

At 1 8. 55. 46-27, cusps about half a diameter apart.
At 18. S/. 16-27, „ one-third „

At 18h. 58™. 46S>27 the Sun showed again, when the cusps were about one-
twentieth of a diameter apart, and connected by a dimly marked ligament,
not nearly so sharp as the " black-drop " of the model in full sunlight.

At 18U. 58m. 50S-07, as far as could be judged, the ligament seemed to
undergo a change in depth of colour, but clouds prevented me from seeing
whether any streak of light Connecting cusps played across it. This is spoken
of in the little table which follows as " the first light on ligament."

My last sight of the planet was at 18h. 58m. 53s-27, at which moment I
thought I saw a very slight wavering streak of light, though the cusps (now
very close) had not fairly met.

I judged that it wanted about five seconds to complete separation of limbs.
I counted the clock-ticks for five seconds, and gave a signal for an estimated
contact at 18h. 58m. 588'27.

The Sun did not appear again until about 19h. 13m., by which time the
planet appeared to be about half its own diameter within the limb. I again

OBSERVATIONS OF INGRESS OF VENUS. 495

inserted the double-image micrometer, and got, at intervals during about
14 minutes, 13 measures of distances of limbs. These were caught in passing
glimpses ; but, owing to incessant variation in the Sun's brightness, they were
very irregular, and can be of little use. The Sun was never quite clear. I
append a list of times and measures ; but, as there was no opportunity of
measuring diameters for zero of micrometer, the measures can only be re-
ferred to the zeros as determined from the model the day before and the day
after the transit.

At about 19h. 28m. the Sun was lost in a large mass of cloud, and further
measures of diameters were impracticable till too late to be of any use. I
therefore again compared the equatorial and transit clocks. Kain set in just
as this was finished and lasted till 21h. 40'"., and the Sun never appeared
again till 10 minutes after the fourth contact, when it shone brightly until
nearly sunset.

Nothing peculiar was noticed in the appearances near or after second
contact. They were just those for which the model when observed on a dull
day had prepared us ; though a certain amount of atmospheric vibration
made the Sun's limb and the planet rather tremulous. In good sunlight
there is no doubt that satisfactory micrometer-measures and satisfactory
observations of contact might have been made. The planet was intensely
black, with a sharp black outline.

[It is remarkable that there is no allusion to a silvery ring round Venus. — G. B. A.]

EPITOME OF THE OBSERVATIONS OF THE TRANSIT OF VENUS, BURNHAM, N.. Z.,

1874, DECEMBER 9.

Clock times were taken by Dent No. 2017, compared with the Transit-
Circle Arnold No. 2 before and after observations.

b m B

At 17. 44. Dent slow of sidereal time at transit hut = + 6'i3.

,. 19. 5o. „ „ „ = + 6-32.

(The correction from transit hut to equatorial hut is = -f o-o3.)

h m s

t

Therefore at 17. 44. Dent slow of sidereal time at equatorial hut = + 6'i6.
„ 19. 56. „ „ „ = + 6-35.

The Adopted Longitude of Burnham is i ih. 29"". i3s'i East of Greenwich.

3 s

496

TRANSIT OF VENUS, 1874. NEW ZEALAND. BURNHAM.

Observations.

Times by Dent

2Ol7.

Dent

Slow.

Local Sidereal
Times.

Greenwich
id ereal Times.

h m s

18.41. 3o-o
1 8. 49. i5'o
1 8. 53. o-o
1 8. 55. 40-0
18. 57. io'o
1 8. 58. 40-0
1 8. 58.43-8
18.58.47-0
18. 58. 52-o

s

+ 6-25

+ 6-26
+ 6-26
+ 6-27
+ 6-27
+ 6-27
+ 6-27
+ 6-27
+ 6-27

h m s

18. 41. 36-25
18. 49. 21-26
1 8. 53. 6-26
1 8. 55.46-27
18. 57. 16-27
1 8. 58. 46-27
18. 58.5o-o7
18. 58. 53-27
i8.58. 58-27

h m s

7. 12. 23-2
7. 20. 8-2

7. 23. 53-2
7. 26. 33-2
7. 28. 3-2
7. 29. 33-2

7- 29- 37'°
7. 29. 40-2

7- 29- 45'2

Cusps subtend about g5° at planet's center
Cusps about § of planet's diameter apart .

» 2 " "
!) 3 » "
» ~SG " "

For the measures made with the double-image micrometer-

December 8. Measures of diameter

on model. No sunlight.

Time 2ih. 3Om. sidereal.

r

r

6-502

13-368

•566

•37i

•55 1

•379

•55 1

•364

•535

•362

•525

•370

•532

•356

•5ig

•358

•521

•359

•523

•35o

•525

•35 1

•572

•326

•572

•344

•554

•348

•58 1

•320

December 10. Measures cf diameter

on model. No sunlight.

Time oh. 30"". sidereal.

•543
•555
•536

•549
•533

•533

6-542

1 3-392
•387
•3g5
•402
•401
•405
•409

13-399

• = 9r'97°

= reading at coincidence of images.

6-542

13-355

6r-542 + i3r-355

= 9r-948 = reading at coincidence of images.

MICROMETER OBSERVATIONS. FINAL EQUATIONS.

497

December 9. Distances of limbs after Ingress, measured with the double-
image micrometer —

Micrometer
Measures.

Times, Dent 2017.

Dent Slow,

Sidereal Times.

Remarks.

r

h m s

s

h m s

8-646 19. 14. 5-5 + 6'3o

19. 14. 1 1 '80

•324 i5. 44-0 -f 6'3o

1 5. 5o'3o

•263

16. 1 8-8 + 6-3o

16. 25'io

•206

i6.35-2 -f- 6-3o

16. 41-50

•i37

17.28-8 + 6-3o

17. 35-io

Very faint.

•091

iS.23-8

+ 6-3o

1 8. 3o-io

•073

1 8. 44-5 + 6'3o

1 8. 00-80

Cloudy.

•062

19. i ro + 6'3o

19. 17-30

Cloudy.

7-908

20. 17-2 + 6-3 1

20. 23'5i

•856

20. 44-0 + 6-3 1

20. 5o-3i

•872

21. 4-8 + 6-3i

21. i ri i

Clouclv.

•921

21. 22-0

+ 6-3 1

2i.28-3i Cloudy.

•448 27. 1 1-2 + 6'32

27. 17-52

[It does not appear that the value of tlic micrometer-scale has been ascertained, and the observa-
tions above, as a mass, are useless. If it is desired to utilize only the earlier observations, a. value
sufficiently accurate may be found from comparison of the earlier with the later, referring also to
the co-efficient of 8 t in the final equation. — G. B. A.]

For the Greenwich sidereal time, 7h. 29m. 41S'3, Major Tupman has computed
the final equation as follows :—

Interpolating for the Greenwich sidereal time, 7h. 29m. 41S'3, the N. P. D.
and Differential R. A. of Sun and planet, and computing from these elements
the Tabular Distance of centers (15'. 38"'25 — "-0319 3 t + "'0141 3 «), and
equating this with the interpolated distance between centers or difference of
semidiameters (15'. 45"'38 + 3 R — 3 r) we obtain the final equation—

+ 7"-i3 = + -0141 8« + -6174 S R.A. — -7429 8 N.P.B. — o"-o3ig S t — % 11 + 8 r.

The equations for the Greenwich sidereal times 7h. 29m. 40s-2 and
7h. 29m. 45S>2 will be found by making 3 t = — 1-1 and -f 3'9 respectively.

[G. B. A.]

3s 2

OBSERVATIONS

AT

BURNHAM, NEW ZEALAND,

IN TABULAR ARRANGEMENT.

500

TKANSIT OP VENUS, 1874. NEW ZEALAND.

TABLE I. — ERROR of COLLIMA.TION of the CKNTEK WIRE of the TRANSIT INSTRUMENT, corresponding
to the Micrometer Reading 2or-ooo.
(The signs are those for Micrometer East.)

Day.

Observer.

Object observed.

Collimation
Error.
Micrometer

20r'000 E.

Day.

Observer.

Object observed.

Collimation
Error.
Micrometer

2O''OOO E.

1874.
October 20

2,1
22
23

26

28
3o

November i

2

3

4

6

7
8

9

10

ii

12

i5
it

20
21
23

25

27
28

29

p

D

c
p
p

c

D

1'
D
C

s

c

D
P

C

C

P

C

p

I)
p

p
p

D
D
P

D

+ 2'6o
+ 2'3l

+ 2'2O

+ 3-3i

+ 1-47

+ 0-62
+ 1-98

+ 2'6y
+ 2-70-

+ i '47
f+ 3-5o 1

l+ 2-93 ;

1874.
November 3o

December i

2

3

4
5

6
8
9

10

18
'9

20
26

27
28

29

3i

1875.
January 5
6
9
ii

12

i3

p
p
p

p
p
p

D
D
P
D

C

D

C
D
C
D

P
P

P
I>

C
p

P
P

M. Mark ...

tt
+ i"97
+ i-58
+ 1-86
+ 1-41
+ 2-43

+ 2'o3

+ 2-43
+ 2-09

+ 2'7O

+ 2-43

+ 2'26

+ 2-76
+ 3-04
+ 3'oo
+ 1-58

f -t o-5o I
1+ o-34 /
+ 0^96

+ 2 '42

+ i -So
+ o-3o
+ o'7o
— o'34
- o-5i

+ 0-17
- o-85
- 0-68
f- o-oS I

1 + 0-2J J
f + O'H 1

I- o-34 /

f + o-ii 1
I + o'o6 J

M Mark

Collimator

M. Mark

M. Mark

- o-i5

— O'll

+ 1-92

+ 2-59

J + 1-4.1 \

t + i 'So /

(- 5-i3)

+ 0-28

f + 0-68 j
I + o 96 /

f + 0-68 \
1+ o-45 J
+ o-56

+ O'62
+ O-62

o'oo
+ 1-18
+ i '44

+ I '21

+ I '07
+ I "02

+ 0-90
+ i-3S
+ i '41

Collimator

M. M. very unsteady . . .

M, Mark

Collimator

M. Mark

M. Mark '.

Collimator

M. Mark
Collimator

M. Mark

M. Mark

M. Mark

ERRORS OF COLLIMATION AND LEVEL.

501

TADLE II. — LEVEL EEROK of the TRANSIT INSTRUMENT at BUIINHAM, determined by SPIRIT LEVEL.

[The sign + indicates that the East Pivot is low.]

Day.

Observer.

Sidereal
Time of
Level Deter-
mination.

Position of Micro- 1
meter.

Level Error
corrected
for
Inequality of
Pivots.

Day. *

Observer.

Sidereal
Time of
Level Deter-
mination.

Position of M icro-
meter.

Level Error
corrected
for
Inequality of
Pivots.

1874.

h rn

'

1874.

h in

.

October 20

c

o. 5o

W

- o-75

November i

p

23. 50

E

+ 8-75

I. 40

W

- 0-95

p

2. 12

E

- 2-85

2

D

23.53

E

- 3-40

2.35

W

- ri5

o. i5

E

- 3-6o

o. 35

E

- 4-1 5

21

D

21. 40

W

+ 3-65

I. IO

W

— 2'6o

22. O

W

+ 5-io

22. 35

W

+ 5-45

3

c

o. 5

E

- 3-o5

22. 5o

w

+ 5-40

I. O

W

- i-95

O. O

E

+ 3-20

I. 10

W

- o-i5

0.25

W

+ 4-20

4

p

23.45

W

+ rgS

22

C

21. 3o

E

+ 3-95

o. 5

w

+ i-65

22. 40

E

I. 20

w

+ i-So

23.17

W

+ 6-o5

2. 15

E

+ ro5

o. 5

W

+ 5-55

5

D

12.25

W

+ 0-40

23

p

22. 0

W

+ 7-45

6

C

23. 45

w

+ 1-80

22. I 5

W

+ 9-15

O. 25

E

+ i-3o

22. So

W

+ 8-60

0.45

E

+ o-65

23.20

E

+ 7'5o

O. O

E

+ 7-o5

7

D

23.55

E

-1- 4' 60

o. 3o

E

+ 6-85

o. i5

E

+ 3-75

I. IO

E

+ 3-45

26

p

1.40

W

+ 3-oo

2. 15

W

+ 3'oo

8

P

23.i5

W

+ 3-65

2.40

W

+ 2-3o

o. 5

E

+ i-85

2.56

W

+ i-35

0.40

E

+ 2-75

3.25

w

+ 2'30

C

0. O

E

+ 3-o5

28

c

4.28

E

+ 2-95

I. 10

E

+ 3-20

5. o

E

+ rgS

5.25

W

+ 2'30

IO

p

18.45

W

- i-65

5. 5o

W

+ 2-85

II

p

2. 2O

W

- 1-70

3o

D

21. 45

W

+ 4'9°

2. 35

W

— I'OO

23. 10

w

+ 4-80

3. 40

E

— 3'co

o. 7

E

+ 3'5o

12

c

o. 40

W

- c-35

o. 3 1

E

+ 3-70

I. 10

w

- o-?5

502

TRANSIT OF VENUS, 1874. NEW ZEALAND. BUKNHAM.

Table II. — Level Error of the Transit Instrument — continued.

Day.

Observer.

Sidereal
Time of
Level Deter-
mination.

8

CJ

s

'c

IS

'£ (D

'» e
£

Level Error
corrected
for
Inequality of
Pivots.

Day.

Observer.

Sidereal
Time of
Level Deter-
mination.

0
§

i

O '^

tS

Level Error
corrected
for
Inequality of
Pivots.

1874.

h »•

„

1874.

h ni

tf

November 1 2

c

i.3o

E

— o-5o

November 2 3

D

O. 2O

E

+ 4-45

2. 5

E

- i-3o

o. 40

E

+ 3'7o

2. 40

E

- 1-80

1.24

W

+ 6*00

I. 52

W

+ 6-55

'4

P

14.35

E

- 3-7o

3.24

E

+ 2'3o

5. 18

E

+ 3-55

i5

p

O. O

E

- 3-40

5.58

E

+ 2-80

o.35

E

- 4-25

6.25

E

+ 3-25

i.3o

W

- 3-5o

26

D

1 5. 3

E

+ 5-65

16

r>

14.44

W

- 4'85

27

D

o. o

W

+ 6'3o

'7

D

12.48

E

- 4-55

0.40

W

+ 6-40

1.36

W

+ 6-85

18

D

22. 5o

W

- 4-4°

1.40

E

+ 5-55

22.57 '

W

— 4'oo

2. 10

E

+ 4'oo

o. 14

W

- 4-25

2.37

E

H- 4'25

o.35

W

— 4'oo

7. 3o?

E

-f 3-70

1.25

E

- 5-85

8. 10

E

-f 2-45

28

P

o. i5

E

+ 2-90

'9

D

1 3. 56

W

— o'6o

o. 45

E

-f 3-i5

2. O

W

+ 2'OO

20

p

23. 25

E

— 0-45

o. 5

W

— o-o5

29

D

O. O

W

+ 2-25

W

, ?._ _

O. 22

W

— 0-45

'

0.45

W

+ 0-75

I. 2O

\v

+ 4-45

I. 22

W

+ o-5o

1.44

E

-1- 2'2O

2. 15

E

+ I '70

21

p

O. O

W

+ i-So

2. 30?

E

+ i-35

'0.45

W

+ 2-00

3o

P

o. 1 5

W

+ i-35

o. 40

W

+ no

22

D

2. 38

W

+ 2-55

i. 3o

W

+ i '90

2. l5

W

+ r3o

23

P

2. O

E

+ 5-65

2. 40

W

+ r3o

2. 15

E

+ 5'g5

December i

P

o. i5

W

+ i *o5

2. 40

E

+ 5*70

3. 3o

W

+ 5-8o

o. 5o

W

H 3'OO

3.40

W

+ 5-8o

i. 3o

E

+ 0*60

2. l5

W

+ i'95

24

r>

3. i3

E

* 5'45

2. 40

W

-l- 2'5o

ERROR OF LEVEL.

503

Table II. — Level Error of the Transit Instrument — continued.

Day.

Observer.

Sidereal
Time of
Level Deter-
mination.

|

s

%*

o

11

Is

Level Error
corrected
for
Inequality of
Pivots.

Day.

Observer.

Sidereal
Time of
Level Deter-
mination.

2

V

§

=s
gfe

'& a

P
PH

Level Error
corrected
for
Inequality of
Pivots.

1874.

h m

//

1874.

h m

//

December 2

p

2. 15

E

+ o'3o

December 19

D

3. 3o

E

"- 3-7o

2. 40

E

+ O'lO

5.io

W

- 3'6o

3.45

W

+ i-65

6. o

W

- 3-io

4. 1 5

w

+ i-g5

6. 20

W

- 3-65

3

p

2. I 5

E

+ r65

20

c

2. 3

w

- 5-55

2.40

E

+ o'8o

2.35

w

- 4-80

3. 5

w

- 3-63

5

p

2. 40

E

+ 2-85

3.45

w

- 3-25

4. iS

W

+ 2'5o

3.55

E

- 5-io

6

D

4.40

W

+ 4'85

4.25

E

- 5-io

5. 12

w

+ 3-55

4.33

W

- 5-25

5.25

E

+ 2-90

6. o

E .

+ 1-25

26

D

2.45

E

— 2'00

6. j5

E

H- 1-25

3. 10

E

- 3'6o

3.25

W

— 2'10

8

D

3. So

W

+ 2-35

6. i5

W

- r55

4.55

W

+ 2'2O

6.45

W

- o-65

5.43

W

+ 3-i5

7. i5

E

- i-85

6. 20

W

+ 4'o5

7.55

E

— 2'IO

7. 2

w

+ 3-95

8. 3o

E

- 3'6o

7-25

E

+ 1-90

7-55

E

+ i-5o

27

C

6.25

E

- 1-25

9

P

2. 40

E

— 0-40

6.55

E

- 3-io

7- iS

W

- o-25

10

D

2. O

W

H- 2'6o

7.35

W

- riS

2. I4

W

+ 1-60

2.35

W

+ 2-80

28

D

2.45

W

+ 0-70

3- 7

w

+ 2-35

1

3. 8

w

— o-6o

3.29

E

+ 1-45

3. 3o

E

- r55

ll

C

i. 55

W

- 4'9°

3.44

E

- i-65

2. I 5

W

- 2-90

5. 40

E

- 2-5o

2. 40

W

- 4-i5

6. o

E

- 2-25

3. o

E

- 5-35

6. 3o

E

- 2-45

»9

D

i. So

E

- 5-iS

29

P

3.45

E

- 1-90

2. O

E

- 5-5o

4.10

E

- 2-65

2. IO

E

- 5-i5

5.52

W

— o'45

2.44

E

- 5-i5

6. 3o

W

+ O'lO

3 T

504

TRANSIT OF VENUS, 1874. NEW ZEALAND. BURNHAM.

Table II. — Level Error of the Transit Instrument — continued.

Day.

Observer.

Sidereal
Time of
Level Deter-
mination.

Position of Micro-
meter.

Level Error
corrected
for
Inequality of
Pivots.

Day.

Observer

Sidereal
Time of
Level Deter-
mination.

2

B

i

(M

O

P3 ^

.2 2

£ QJ

1S
PH

Level Error
corrected
for
Inequality of
Pivots.

1875.

h m

//

1875.

h m

f.

January 5

p

4. i5

W

+ 5-75

January i 1

r

5.20

E

+ 5'io

4.55

E

+ 4' 80

6. o

W

+ 6-85

6. 5

E

+ 4'9°

6.25

W

+ 5-75

6.25

E

+ 5'20

. 12

p

5. 10

E

+ 4'25

6

p

4.iS

W

+ 5-8o

5.45

E

+ 3'8o

4.45

W

+ 5'3o

• 6. 5

W

+ 3-90

6. 5

E

+ 5-75

6. 3o

W

+ 370

9

c

5.55

E

+ T9°

i3

p

5.25

E

+ 470

6. 20

E

+ 8-40

5.45

E

+ 4'3o

6. 5o

E

+ 6-80

6. 5

W

+ 4'25

7.i5

W

+ 8-45

6.25

W

+ 4-20

TABLE HI. — AZIMUTH EEKOB of the TRANSIT INSTRUMENT at BURNHAM, and OBSERVATIONS of the

MERIDIAN MARK.

[The sign + indicates that the Optic Axis points East of North.]

Day.

Approx.
Local
Mean
Time.

Observer.

Objects observed.
M. M. = Meridian Mark.

Apparent
Error of
Azimuth.

Remarks.

1874.
October 20

21

22
23
26

h in
12. 30

9. 8
10. 9

8. 3
9. S

8. o
9- '

II. 10

12. IO

p

D

r>

c
c

p
p

p
p

2 Octal

T Octar
o Octar

c Octal
T Octal

c Octal
T Octai

M.M.

2 Octai

tis S.P. and o Arietis
itis v Pis

//
- 0-6

— 14-0
- 8-8

- 9-0
- 9-2

- i5-6

- i3-o

E. 20'

itis S.P

•373, W. I9"6
£' Ce

70 . .

t.i . .

- 16-2

ERRORS OF LEVEL AND AZIMUTH.

505

Table III. — Azimuth Error of the Transit Instrument, &c. — continued.

Day.

Approx.
Local
Mean
Time.

Observer.

Objects observed.
M. M. = Meridian Mark.

Apparent
Error of
Azimuth.

Remarks.

1874.
October 28*

3o
November i

z

3
4

6

7
8

9

10

ii

12

15

b in

15.43

9-36

9.56

8. 3o
9. o

10. 0

Afternoon
Night
9.32

Night
9.22

11.40
Night |

8. 4
9. 10

9-i5

Night

9. i5
9.40

9-i5
Night

3. ii

3.21

n. 6
ii. 26

9- 4

II. 2
8.40

10. 5

c
c

D
D

n

p
i>
p

D
D
D

c
c

p
p
p

c

c

D
D

p
p

c

c

p

p

p
p

c
c
c

p
p

\

tt
+ 33-i

M. M. shifted 3 • 5 inches to
East before this observation.

Nov. 2, 5", L.M.T. The level
and azimuth were adjusted.

Azimuth Error adopted + 9" -6.
M. M. very unsteady.

M.M. E. 19-369, W. 20-653

+ 35-6

M.M. E 19-374 W 20-696

+ 33-4

1 + 35-o
j

M.M. E. ig-336, W. 20-749

M.M. E. 19-345, W. 20-746

M.M. E. I9-353, W. 20-758

M.M. E. 19-647, W. 20-450

M.M. E. 19-981

+ 1-6

+ 1-6
+ 9-0

+ 4-6
+ 1-9

+ 8-2
+ iS-2

o Octantis Brisbane 4091 S P .

M.M. E. 19-869, W. 20-183

z Octantis S.P a Arietis

M.M. E. 19-838, W. 20-286

M.M. E. 19-820, W. 20-284

o Octantis Brisbane 4091 S P . .

M.M. E. 19-735, W. 20-333

+ 23-9

M. M. E. 19-629, \V. 20-464

M.M. E. 19-475, W. 20-575

M.M. E. 19-497, W. 20-568

z Octantis S.P S Arietis

+ 22-7

M.M. E. 19-275, W. 20-543

+ 28-6

M.M. E. 19-322, W. 20-688

z Octantis S.P Brisbane 4091 S.P. .

+ 3l'2

+ 41-2

M.M. E. 19-256, W. 20-779

* There is HO record between these dates of the azimuth adjustment having been altered.

ST 2

506

TRANSIT OF VENUS, 1874. NEW ZEALAND. BURNHAM.

Table III. — Azimuth Error of the Transit Instrument, &c. — continued.

Day.

Approx.
Local
Mean
Time.

Observer.

Objects observed.
M. M. = Meridian Mark.

Apparent
Error of
Azimuth.

Remarks.

1874.
November 18

20

21

23

25

*7

28
29

3o
December i

2

3

4
5

6

h ra

8.35
Night

7.i5
8.25

8.21

8.47

10. 20

8. 5

8. ii
Night
10. 8

8. 2

Night

7.58
Night
9.56

7-54

9. Si

7. 5o

9-47
9-44

9.39
9.52

IO. 2

i3. 10

D
D

p

p

p
p

p
p

D

D
D
D

P
P

D
D
D

P
P
P
P

P
P
P

P
P

P
P

P

P
P

D
D

o Octantis and Brisbane 4091 S.P

//
+ 43-6

M. M. unsteady.

> Adopted + 1 2" -9.
I Adopted +n" -i 5.

> Adopted + 1 2" -3.

M.M. E. 19-131, W. 20-890

M. M. E. 19-865, W. 20- 156.

+ I'2

+ i'4

M.M. E. 19-876, W. 20-124

M.M. E. 19-955, W. 20-096

z Octautis S.P 67 Ceti

- o-5
+ i3-5

+ 7-8
+ ii -i
+ 14-2

+ 18-9

+ I2'9

+ 8'7

Brisbane 4091 S.P. . . . e Piscium

M.M. E. 19-741, W. 20-295

2 Octantis S.P v Piscium

Brisbane 4091 S.P. ... e Piscium

M.M. E. 19-716, W. 2o-3i6

Brisbane 4091 S.P. . . . & Hydri . , .

M.M. E. 19-743, W. 2o-3o8

2 Octantis S.P a Eridani

+ 13-6
+ n-8

Brisbane 4091 S.P f1 Piscium

M.M. E. 19-736, W. 20-335

M.M. E. 19-742, W. 20-327

+ 12-8
+ i3-o

Brisbane 4091 S.P. ... f Piscium

M.M. E. 19-713, W. 20-337

z Octantis S.P 7* Ceti .

+ 12-8
+ n-8

+ i3-4

z Octantis S.P -f Ceti

M. M. E. 19-777, W. 20' 3og

z Octantis S.P 67 Ceti

M.M. E. 19-771, W. 2o-3i6

M.M. E. 19-745, W. 20-329

M.M. E. 19-700, W. 20-418

M.M. E. 19-670, W. 20-416

+ 16-4
+ 18-1
+ >7'9

M.M. E. 19-636, W. 20' 444

ERRORS OF AZIMUTH.

507

Table III. — Azimuth Error of the Transit Instrument, &c. — continued.

Day.

Approx.
Local
Mean
Time.

Observer.

Objects observed.
M. M. = Meridian Mark.

Apparent
Error of
Azimuth.

Remarks.

1874.
December 8

h m

10. 3o

r>

M. M. E. 19-633 W. 20-468

//
+ 18-8

9

9. 36

p

M. M. E. 19-637, W. 20-471

10

9. 20

D

+ 16-9

D

MM. E 19-591, W 2o'5i6

18

8.39

c

— 0-7

c

19

7. 27

D

10. 7

D

MM E 19-935, W 20-078

12. 2O

D

— O'2

20

$,3i

C

z Octantis f Tauri

- 8-4

26

i3.5i

D

— IO'9

14. 19

D

M M. E. 20- 1 57, W. 19-939

— ii-o

27

11.48

C

— 1-4

C

M. M. E. 20-127, W. 19-936

28

D

D

— 0-7

1 1. 4.0

p

- i5'4

3!

p

1875.

MM E 20-017 W 19-965 ,.

MM E 19-988 W 20-018 .

ii. i3

— 4-1

6

8 56

P

M.M. E. 19-987, W. 19-984

- 4-6

II. O

C

— 9-0

c

MM E 20-088 W 19-887

1 1

q. 36

p

MM E 20-064 W 19-933

10. 4.0

p

— 10-9

ii 6

M.M. E 20-043, W. 19-965 .

508

TRANSIT OF VENUS, 1874. NEW ZEALAND. BURNHAM.

Table III. — Azimuth Error of the Transit Instrument, &c. — continued.

Approx. ^
j. Local £ Objects observed.

^ean 1 M. M. = Meridian Mark.

J.1HIC. »-Q

0

Apparent
Error of Remarks.
Azimuth.

1875. ,, „,
January 12 9.32 p M. ]
10.47 p a- O

II. 2 P M.I

i3 9.28 p M.I
10. 43 P IT Q
10.58 p M.J

if. E. 20-071, W.

- 7-0
- 7'9

v Orionis .

IQ ' OOJ.

Ii. E. 20-057, W.
1. E. 20-074, W.

v Orionis . .

I Q * Q "\A.

I. E. 20-068, W.

*

ABSTRACT of TABLES IV. and V. — TRANSITS of STARS and of the MOON, and Inferred R.A. of the

MOON'S LIMB at TRANSIT.

Day,

1874.

Observer.

O
I

a .

°K
11
I

Number of Transits
of Clock Stars.

Number of Transits
of Circumpolar

Stars.

to «*-.

a °

H

E B a

.-!£«

I'M?

Clock Slow
on Local
Sidereal
Time.

Clock's
Losing
Rate.

a

i

Clock Time of
Transit of
Moon's Limb
over Meridian.

Right Ascension
of Moon's Limb
on Meridian.

h in

a

a

h m »

Oct. 20

c

W.

4

I

p

E.

4

i

1 1.42

+ 7-55

p

W.

i

J

21

D
D

W.
E.

7

2

2
I

J23. 4

+ 13-76

+ 6-97

I.

22. 25. 38-10

22.25.5i-65

22

C
C

E.
W.

5
5

2
I

},,,

+ 21-61

+ 7-83

I.

23. 20. 11*46

23. 20. 33-to

23

P
p

W.
E.

3
5

2
I

J23.34

+ 8-40

I.

o. 14. 54-55

o. 1 5. 3-02

26

P

\V.

8

I

2.54

+ 23-84

+ 4-92

n.

3. ii. 36-44

3.12. 0-34

28

C

c

E.
W.

6

5

I

| 5.io

+ 32-68

+ 4-22

ii.

5.22. 54-27

5. 23. 26- 94

3o

D
D

W.

E.

2

4

I

I

| o. 8

+ 4i-i5

+ 4-72

ERRORS OF AZIMUTH, AND TRANSITS.

509

Abstract of Tables IV. and V. — Transits of the Stars and of the Moon, &c. — continued.

Day,

1874-

Observer.

1 .
Jl

Number of Transits
of Clock Stars.

Number of Transits
of Circumpolar

Stars.

0<o
H

V

JTSQ

Clock Slow
on Local
Sidereal
Time.

Clock's
Losing
Rate.

j

I «

Clock Time of
Transit of
Moon's Limb
over Meridian.

Right Ascension
of Moon's Limb
on Meridian.

h m

8

h m ,

h m s

Nov. i

p

E.

i

O. 2

+ 2-83

2

D
D

E.
W.

3
3

2

| 0. 30

+ 3-36

+ 0-52

3

C

E.

3

| °-47

+ 5-23

+ J-85

•

C

W.

3

4

P

W.

4

,

r ^* 4^

+ 6- jo

+ 0-84

P

E.

2

i

J

6

C
C

W.
E.

3
3

>• O. 21

+ 9-03

+ i-Si

7

D

E.

4

2

o. 3o

+ 11-57

+ 2-52

8

P

W.

4

>• o. 5

+ 14-36

+ 2-84

P

E.

4

2

9

C
C

E.
W.

2

2

| o.36

+ 16-32

+ 1*92

i i

p

W.

3

I

[• 3.23

+ 21-48

p

E.

4

12

C
C

W.

E.

4
4

I
I

| 1.28

+ 20-17

- 1-42

iS

p

E.

4

2

,

r- I. l3

+ 16-89

— i-io

p

W.

4

it

D
D

W.
E.

6

2

2

J23. 57

+ 11-81

- 1-71

I.

22. 56.25-98

22. 56. 37-84

20

p

E.

4

,

P

W.

5

2

1 0.24

+ 0*06

I.

0.42. 4-30

0.42. 4-53

21

P

W.

2

23

P
P

E.
W.

5
3

I

} 2.56

+ 3-63

+ i-iS

I.

3.38.15-97

3.38. 19-65

25

D

E.

W.

10

3

2

I 3.56

+ 8-57

+ 2-42

I.

5.56. 10-82

5.56. 19-62

510

TRANSIT OF VENUS, 1874. NEW ZEALAND. BURNHAM.

Abstract of Tables IV. and V. — Transits of Stars and of the Moon, &c. — continued.

o

s

«J '~

So

^

Day,
1874.

bserver.

jsition of Micr
meter Head.

umber of Transi
of Clock Stars.

if

i

°0

tl

g 0 rJl

Bm _

1'| 2
ESS

0) rt +3

fi

g'oO

Clock Slow
on Local
Sidereal
Time.

Clock's
Losing
Rate.

O

3

O

i
•s-g
•81

3 '•!.

Clock Time of
Transit of
Moon's Limb
over Meridian.

Right Ascension
of Moon's Limb
on Meridian.

O

PH

fc

K

*j

3

h m

i

s

h m s

h m •

Nov. 27

D
D

W.
E.

4
5

1

I

I 3. 3o

+ 14-20

+ 2-84

II.

8. 7.29-15

8. 7.43-82

28

P
P

E.
W.

4

2

I

},25

+ 16-07

+ 2-o5

29

D

W.

3

2

I 1.2,

+ 17-18

+ I- II

D

E.

2

I

*

3o

P

W.

3

2

} i.33

+ 18-88

+ 1-69

P

E.

4

J

Dec. i

P

W.

3

2

} !.42
'

+ 19-77

+ 0-88

P

E.

3

2

P
P

E.
W.

3
4

I

},„

+ 20-48

+ 0-66

3

P

E.

3

I

2. 3l

+ 21-60

+ i- 16

5

P
P

E.

W.

5
3

} 3.40

+ 23-42

+ 0-89

^- *

6

D

D

W.
E.

3
3

I

}-'

+ 24-33

+ o-85

8

D

W.

4

6. 20

+ 25-61

+ o-63

9

P

E.

I .

10

D

D

W.
E.

2
2

I

} 2-46

+ 25-75

+ 0-08

18

C

W.

3

| 2. 30

+ I3-37

(- i-55)

C

E.

3

'9

D
D

E.
W.

6

3

I

} 3.20

+ 10-70

- 2-58

I.

2. 7. 50-42

2. 8. i-3g

20

C

W.

4

r 4- 4

+ 8-62

— 2-02

C

E.

4

J

26

D

W.

4

}5.22

- 3-5o

— 2-00

D

K.

3

I

J

TRANSITS OF STARS AND MOON.

511

Abstract of Tables IV. and V.— Transits oi' Stars and oi' the I\loon, &c.— continued.

"

S

£* ^<S

.

Day,

1874.

o>

Ja

9

C t-

.°Z

O

*s

<n ^

It
<~ "

L|

B

111
^S-M

o

§0
4, "SO

Clock Slow
on Local
Sidereal
Time.

Clock's
Losing

Ente.

O

B)

O

1

t»

Clock Time of
Transit of
Moon's Limb
over Meridian.

Right Ascension
of Moon's Limb
on Meridian.

C

— ''

& ^

"

li in

8

1, m .

h m I

Dec. 27

c

E.

3

} 7- 4

- 3-5o

o-oo

c

W.

3

'

zS

D

W.

3

} 4---
'

- 3-25

+ 0-28

D

E.

6

i

29

P
P

E.

3
4

i

},4

- 2-88

+ 0-36

1875.

Jan. 5

P
P

\V.

E.

3
3

i

},,2

+ 2-21

+ 0-73

6

P

W.

3

; 5 3

+ 3-55

+ i-35

P

E.

2

^

9

C

E.
W.

3
3

i

| 6. 56

+ 8-63

+ 1-64

ii

P

E.
W.

3
3

i

} 5.48

+ 10-85

+ 1-14

12

P

E.

3

| 5.48

+ 10-82

— o-o3

P

W.

3

i

i3

P

r

E.
W.

3
3

i

} 5-45

4. 11-12'

+ o-3o

-

6 U

512

TRANSIT OF VENUS, 1874. NEW ZEALAND. BURNHAM.

TABLE VI. — LONGITUDE of BURNHAM, N. Z., from the observed R.A. of the MOON on the MERIDIAN.

,0

Day.

C
w

.0

a

"a
c
o

Observed R.A.
of the Moon's Limb
on the Meridian.

Longitude by the Ephemeris.
c = the Correction required
to the Moon's Tabular R.A.

Adopted
Value of e.

Resulting Lon-
gitude East
of Greenwich.

C

%

1874.

h in »

h m s

.

h ill 9

October 21

D

I.

22.25.5i-65

1 1 . 29. 22 ' 20 + 26 • 09 e

- 0-48

11.29. 9'7

22

O

I.

23. 20. 33- 10

II. 29. 25-38 + 26-43 e

— 0-54

ii. 29. ii -i

23

e

I.

o. 1 5. 3-02

II. 29. 23-95 + 26-32 e

- o-63

11.29. 7'4

26

r

II.

3.12. 0-34

II. 29. 29-43 + 22-81 €

- 0-86:

ii. 29. 9-8

28

c

II.

5. 23. 26-94

11. 29. 34-2O + 20-98 e

- 0-88

ii. 29. i5'7

November i 8

i>

I.

22. 56. 37-84

11.29.24-38 + 27'4oe

- o-38

1 1. 29. 14- o

20

p

I.

0.42. 4-53

II. 29. 18-21 + 26-79 e

- °'49

ii. 29. 5'i

23

p

I.

3.38. 19-65

II. 29. 21-92 + 38-o8 e

- o-75

11.29. 5-3

25

n

II.

5. 56. 19-62

ii. 29. 32- 52 + 20-98 e

- o-83

n. 29. i5- 1

27

D

II.

8. 7.43-82

ii. 29. 36-24 + 23-53 e

- 0-82

ii. 29. 17-0

December 19

D

I.

2. 8. I '19

ii. 29. 26'33 + 25'32 e

- o-53

ii. 29. 12-9

The Mean Resulting Longitude from 7 transits of the First Limb is 11.29. 9'4

That from 4 transits of the Second Limb is n ™ ir-n

General Mean

TABLE VII. — LONGITUDE of BURNHAM, from the observed AZIMUTHS of the MOON.

Moon I.

Moon II.

"5 a

~ a

fci

CJ

i* £ . Mean Inferred

Id

t, t, . Mean Inferred

Day.

o>

JO

O

•° f, g Longitude for Day
|°'B (East).

Day. |

S

•2 J | Longitude for Day
|°~ (East).

1874.

h m s

1874.

h in s

October 23

D

4 ii. 29. ii- 1

October 26 c

4 11.29.20-9

December 18

P

8 n. 29. 27-7

28 D

4 n. 29. 23-4

'9

C

6 ii. 29. 29- 3

December 27 i>

4 ii. 29. i6-5

20

D

6 II. 29. I2'2

28 c

6 ii. 29. 14-8

29 D 6 n. 29. 29-0

Mean .

11. 2Q. 2O* I

i

. . ii. 29. 20- 9

h

Mean Longitude East, by observed A

zimuths ij

. 29. 20-5

TRANSIT OF VENUS, 1874.

APPENDIX.

APPENDIX.

APPENDIX I. — EXTRACT from INSTRUCTIONS to OBSERVERS.

(Instructions were prepared in considerable detail for all the circumstances in which they
appeared necessary, but I confine myself in the following extract to the two paragraphs which
applied to the actual observation.)

Section (X.), Article 1 1 : —

" The record of observation will be made thus :

" For a micrometer-observation, the observer will give the word ' now ' or other sudden signal,
for time ; the assistant at the clock will enter the time ; the observer will give the micrometer-
reading, and the assistant will write down the micrometer-reading.

" For the observation of internal contact, where two or three phenomena may present themselves
at intervals of time too small to admit of writing at length, the observer will simply give ' now '
for a time to be recorded, and at next phenomenon will simply give ' now,' the time of which is to
be recorded in the book, leaving a gap of several lines ; and so on, as often as may be necessary.
When the pressure of phenomena ceases, the observer is to give from memory the details of the
phenomenon to which each time-entry applies, and the assistant is to enter them in their proper
places."

APPENDIX II. — CORRECTIONS to the TABULAR RIGHT ASCENSION of the MOON.

(Major Tupman examined most carefully all the observations of the Moon made at. the principal
Observatories of Europe, through the time included in the observations connected with the Transit
of Venus, and exhibited in a graphical form in the Monthly Notice of the Royal Astronomical
Society for March 1877, vol. 37, page 256, the corrections to the R.A. and N.P.D. of the Moon
printed in the Nautical Almanac. The corrections to R.A. are measured from Major Tupman's
curves, and are exhibited numerically in the following table. They have been used in the
reductions throughout by Major Tupman.)

Day.

Correction
to R.A.

of N. A.

Day.

Correction
to R. A.
ofN.A.

Day.

Correction
to R. A.
ofN.A.

Day.

Correction
to R. A.
of N. A.

1874.
Sept. 14

- o-37

1874.
Sept. 18

B

- °'44

1874.

Sept. 22

I

- °'49

1874.
Sept. 26

— o'yo

i5

— 0-39

'9

— 0-45

23

- o-53

27

- 0-78

16

— O-42

20

— 0-46

24

- o-5S

28

- o-83

>7

- o-43

21

- o'47

25

- 0-64

29

- 0-84

3x

(2)

TRANSIT OF VENUS, 1874. APPENDIX.

Day.

Correction
to R. A.
ofN.A.

Day.

Correction
to 11. A.
of N. A.

Day.

Correction
to R. A.

ofN. A.

Day.

Correction
to R. A.
of N. A.

1874.

8

1874.

s

1874.

X

1875.

s

Sept. 3o

— 0-81

Nov. 4

- o-55

Dec. 17

- °'44

Jan. 23

- 0-66

5

- 0-52

18

— 0^46

24

- 0-66

__ o* 76

6

- °'47

'9

— o-5o

25

- o-65

12

— 0-43

10

- o-55

26

— 0-62

2

— 0-72

3

- 0-66

i3

— 0-42

21

- o-Sg

27

- o-57

4

- o-63

14

— 0-40

22

— 0-64

28

- 0-52

5

- o-58

i5

- o-37

23

- 0-68

29

— 0-46

6

- 0-55

16

— 0-34

24

- 0-74

3o

— 0-43

7

- o-53

17

— 0'32

25

- o-75

3i

- 0-39

18

- 0-34

26

— 0-76

12

— O'2O

i3

- 0-27

'9

- o-38

27

- °'74

Feb. i

- o-37

2O

Q. . .

28

- 0-66

14-

— 0-28

TT"

7

— 0-29

i5

- o-3i

21

- o-5i

29

— o'6o

8

— o'3o

16

— 0-34

22

— 0-59

3o

— 0*54

9

- o-33

17

- o-37

23

- 0-68

3i

— o'5o

10

- o-35

18

— 0-40

24

- 0-76

ii

- o-38

19

- °'44

25

- o-85

1875.

12

— 0-41

20

- °'47

26

- o-93

Jan. i

— 0-46

i3

— 0-45

21

- 0-50

27

— 0-90

2

- °'44

»4

- o-5i

22

28

- 0-80

3

— 0-43

i5

- o-55

23

— 0-59

29

— 0-67

10

— 0-41

16

- o-58

24

- 0-66

3o

— o'6o

II

- 0-41

17

— o'6o

25

- o-75

12

— 0*42

18

- o-58

26

- 0-79

Dec. i

- o-55

i3

— 0-43

19

- o-55

27

- 0-80

2

- o-53

J4

- o-45

20

- o-53

28

- 0-78

3

- o-5i

i5

— 0*46

21

- °'47

29

— 0*76

4

— o-5o

16

- 0-48

22

- °'44

3o

- o-73

5

- °'49

17

— o- 5o

23

— 0-41

3i

— 0-70

12

- o-34

18

— 0-54

24

- o-38

13

— 0-34

'9

- o-56

25

- o-36

Nov. i

- 0-66

14

- o-35

20

- o-58

26

- o-35

2

— 0-64

i5

- o-36

21

— O'62

27

— 0-34

3

— 0-59

16

— 0-40

22

- o-65

CORRECTIONS TO MOON'S TABULAR PLACE. TABULAR PLACES OF SUN AND VENUS. (3)

APPENDIX III. — GEOCENTRIC ELEMENTS of the POSITIONS of the SUN and VENUS for times
near to those of the INGRESS and EGRESS of VENUS at the SUN'S LIMB, formed by INTER-
POLATION between the PLACES in the NAUTICAL ALMANAC.

Greenwich
Sidereal Time
on Dec. 8.

K. A.

of Sun.

N. P. D.

of Sun.

K. A.
of Venus.

N. P. D.

of Venus.

Greenwich
Sidereal Time
on Dec. 8.

K. A.

of Sun.

N. P. D.
of Sun.

E. A.

of Venus.

N. P. D.

of Venus.

0 /

II

0 t

It

0 /

If

o /
tt

0 /

//

0 /

it

o /
//

0 /

rt

h m

h m

255.43.

112.48.

255.57.

112.37.

255.44.

112.48.

255. 57.

112. 37.

6. So

43-3o

32-35

64-07

46-22

7-i5

5i-73

38-5?

25'oo

26-42

5i

46-03

32 -60

62-51

45-43

it

54'47

38-82

23-43

25-63

52

48-77

32-85

60 -94

44-63

17

57-2i

39-07

21-87

24-84

53

5i-5i

33-io

59-38

43-84

18

59-94

3g-3i

20- 3i

24-04

54

54-25

33-35

57-82

43 -o5

'9

62-68

39-56

18-74

23-25

255.43.

112.48.

255. 57.

112. 37.

255-45.

112.48.

255. 57.

112. 37.

6.55

56-98

33-6o

56-26

42-26

7.20

5-42

39-81

17-18

22-46

56

59-72

33-85

54-69

4I-47

21

8-16

40-06

15-62

2,1 ' 67

57

62-46

34-09

53-i3

40-68

22

10-90

40- 3i

14-06

20-88

58

65-20

34-34

si-Si

39-88

23

13-63

4° "56

12-49

2O-O8

59

67-93

34-59

So- oo

39-09

24

16-37

40-81

10-93-

19-29

255.44.

112.48.

255. 57-

112. 37.

255.45.

112. 48.

255. 57.

112. 37.

7- °

10-67

34-84

48-44

38-3o

7.25

19-11

41 -o5

9-37

iS-5o

I

13-41

35-09

46-88

37-5i

26

21-84

4i-3o

7-80

17-71

2

i6-i5

35-34

45-32

36-72

27

24-58

41-55

6-24

16-91

3

18-88

35-59

43-75

35-92

28

27-32

41-80

4-68

16- 12

4

21-62

35-83

42-19

35-i3

29

3o-o6

42-05

3-n

i5-33

255.44.

112.48.

255.57.

112.37.

255-45.

112. 48.

255.56.

112. 37.

7- 5

24- 36

36-o8

40-63

34-34

7.3o

32-79

42'30

6i-55

I4-54

6

27-10

36-33

39-06

33-55

3i

35-53

42-,55

59-99

13-74

7

29-83

36-58

37-5o

32-76

32

38-27

42-79

58-43

12-95

8

32-57

36-83

35-94

31-96

33

41-00

43-04

56-86

12-16

9

35-3i

37-08

34-37

3i-i7

34

43-74

43-29

55- 3o

ii-37

255.44.

112.48.

255.57.

112. 37.

255.45.

112.48.

255.56.

112. 37.

7. 10

38-o5

37-33

32,- 8 1

3o-38

7.35

46-48

43-54

53-74

10-57

ii

40-78

37-57

3i-25

29-59

36

49-22

43-79

52-17

9-78

12

43-52

37-82

29-69

28-80

37

Si-gS

44-o3

5o-6i

8-99

i3

46-26

38-o7

28-12

28-00

38

54-69

44-28

49 -oS

8-20

14

48-99

38-32

26-56

27-21

39

57-43

44-53

47-48

7-40

Semi-
diameter
of Sun.

Parallax
of
Sun.

Semi-
diameter
of Venus.

Parallax
of
Venus.

Semi-
diameter
of Sun.

Parallax
of
Sun.

Semi-
diameter
of Venus.

Parallax
of
Venus.

1 6'. 1 6" -80

9" -09

3i"-42

33"-86

1 6'. 1 6" -80

9" -09

3i"-42

33"-86

3x2

(4)

TRANSIT OF VENUS, 1874. APPENDIX.

Greenwich
Sidereal Time
on Dec. 8.

R. A.

of Sun.

N. P. D.
of Sun.

R. A.
of Venus.

N. P. D.
of Venus.

Greenwich
Sidereal Time
on Dec. 8.

R.A.

of Sun.

N. P. IX
of Sun.

R.A.
of Venus.

N.P.D.
of Venus.

0 /

//

o /
r/

O '

tf

o /
//

o /
//

o /

H

0 /

II

0 /

it

h m

h in

255.46.

112. 48.

255. 56.

112. S?.

255. 46.

112. 48.

255.56.

112. 36.

7.40

o'i6

44-78

45-92

6-61

7.45

i3-85

46'O2

38-n

62-65

4'

2-90

45-o3

44-36

5-82

46

16-59

46-27

36-55

6!-86

42

5-64

45-28

42-80

5-o3

47

19-32

46-52

34-98

61 -06

43

8-38

45-52

41-23

4-23

48

22-06

46-76

33-42

60-27

44

ii'ii

45-77

39-67

3-44

49

24-80

47-01

3i-86

59-48

-

255.46.

112. 48.

255. 56.

112. 36.

7. 5o

27-54

47-26

30-29

58-69

Semi-

Parallax

Semi

Parallax

Semi-

Parallax

Semi-

Parallax

diameter

of

diameter

of

diameter

of

diameter

of

of Sun.

Sun.

of Venus.

Venus.

of Sun.

Sun.

of Venus.

Venus.

1 6'. 1 6" -80

9" -09

3i"'42

33"- 86

1 6'. 1 6" -80

9" -09

3i"-42

33"- 86

255. 46.

112. 48.

255. 56.

112. 36.

255. So.

112.49.

255.54.

ii2. 35.

8. o

54-91

49 '74

14-67

50-76

9. 20

33-90

9-54

9-68

47-34

255.47.

255.55.

255.5i.

255. 53.

8. jo

22-28

52-22

59-04

42-81

9. 3o

1-28

I2-OI

54'o5

39-42

8.20

49-66

54-70

43-42

34-91

9.40

28-65

14-48

38-43

31-49

9. 5o

56-o3

16-94

22-80

23-56

255.48.

8. 3o

I7'o3

57-I8

27-79

26-98

255. 52.

8.40

44-40

5g-65

12-17

19-05

IO. O

23-41

19-41

7-18

i5-63

255.49.

112.49.

255. 54.

255. 52.

8. So

11-78

2'l3

56-54

n-i3

IO. IO

5o-78

21-87

5i-56

7-70

9. o

39-i5

4' 60

40-92

3-20

255. 53.

112. 34.

JO. 2O

18-16

24-34

35-94

59-77

255.5o.

112. 35.

9. 10

6-52

7-07

25-3o

55-27

io. 3o

45-54

26-80

20-32

5l'84

Semi-

Parallax

Semi-

Parallax

Semi-

Parallax

Semi-

Parallax

diameter

of

diameter

of

diameter

of

diameter

of

of Sun.

Sun.

of Venus.

Venus.

of Sun.

Sun.

of Venus.

Venus.

16'. i6"-8i

9" -09

3i"'42

33"-86

16'. i6"-8i

9" -09

3i"-42

33" -86

TABULAR PLACES OF SUN AND VENUS.

(5)

•§.J3 oo

R. A. N. P. D.

R. A.

N. P. D.

H .J3 <»'

R. A. N. P. T). R. A.

N. P. D.

? a

of Sun.

of Sun.

of Venus.

of Venus.

'i ^ o

of Sun. of Sun.

of Venus.

of Venus.

S 2 Q

S'Bo

.

u « s

° /

0 /

0 /

0 /

t & a

0 ' 0 /

o /

o /

O-o o

o3

tc

"

h m

h m

255.53.

112.49.

255. 52.

112. 34.

255.55.

112.49.

225.51.

112. 34.

10. 3o

45-54

26-80

20-32

5i-84

II. O

7-68

34-17

33-46

28-05

3i

48-28

27-04

18-76

5i-o5

I

i o • 42

34-42

31-90

27-26

32

5 1 -02

27-29

I7-I9

So- 26

2

i3-i6

34-66

3o-33

26-46

33

53-75

27-53

iS-63

49-46

3

i5'89

34-91

28-77

25-67

34

56-49

27-78

14-07

48-67

4

i8-63

35-i5

27-21

24-88

255. 53.

112.49.

255. 52.

112. 34.

255.55.

112.49.

255.5i.

112. 34.

10. 35

59-23

28-02

iz-Si

47-88

u. 5

21-37

35-40

25-65

24-08

36

61-97

28-27

10-95

47-08

6

24-11

35-64

24-09

23-29

37

64-71

28-52

9-38

46-29

7

26-85

35-89

22-52

__ 22 'So

38 67-44

28-76

7-82

45 -5o

8

29-58

36-i3

20-96

21-70

39

70-18

29-01

6-26

44-7I

9

32-32

36-38

19-40

20-91

255. 54.

112.49.

255.5i.

112. 34.

255.55.

112.49.

255.5i.

112. 34.

10. 40

12-92

29-25

64-70

43-9I

II. 10

35-o6

36-63

17-84

2O- 12

4'

i5-66

29-50

63-14

43 * 12

ii

37-80

36-87

16-28

I9-32

4*

18-40

29-75

61-57

42-33

12

40-54

37-i2

14-71

18-53

43

21'l3

29-99

" 60 -01

41-53

i3

43-27

37-36

i3-i5

17-74

44

23-87

30-24

58-45

40-74

14

46-01

37-61

11-59

i6-95

255. 54.

112.49.

255. 5i.

112. 34.

255.55.

112.49.

255.5i.

112. 34.

10. 45

26-61

30-48

56-89

39-95

ii. i5

48-75

37-85

io-o3

i6-i5

46

29-35

3o-73

55-33

39'l5

16

5i-49

38-10

8-47

i5-36

47

32-09

30-97

53-76

38-36

'7

54-23

38-34

6-90

14-57

48

34-82

3l'22

52-20

37-57

18

56-96

38-59

5-34

13-77

49

37-56

3i-47

50-64

36-78

19

59-70

38-84

3-78

12-98

255. 54.

112.49.

255.5i.

112. 34.

255.56.

112.49.

255.5o.

112. 34.

10. So

40- 3o

Ji-71

49-08

35-98

II. 20

2-44

39-08

62-22

12" 19

5i

43-04

3i-96

47'52

35-19

21

5-i8

3.9-33

60-66

II-39

52

45-78

32-20

45-95

34-40

22

7-92

39-57

59-09

10-60

53

48-5i

32-45

44-39

33-60

25

io-65

39-82

57-53

9-81

54

5i-25

32-70

42-83

32-8i

24

i3-39

40-06

55-97

9-01

255. 54.

112.49.

255. 5i.

112. 34.

255.56.

112.49.

255. 5o.

112. 34.

10.55

53-99

32-94

41-27

32-02

11.25

i6-i3

40- 3i

54-41

8-22

56

56-73

33-19

39-71

3l'22

26

18-87

40-55

52-85

7-43

57

59-47

33-43

38-14

3o-43

27

21-61

40-80

5i-28

6-63

58

62-20

33-68

36-58

29-64

28

24-34

41-04

49-72

5-84

59

64-94

33-92

35-02

28-84

29

27-08

41-29

48-16

5-o5

Semi-

Parallax

Semi-

Parallax

Semi-

Parallax

Semi-

Parallax

diameter

of

, diameter

of

1

diiimeter

of

diameter

of

of Sun.

Sun.

of Venus.

Venus.

of Sun.

Sun.

of Venus.

Venus.

1 6'. 16" -82

9" -,09

3l"-42

33"-86

16'. i6"-82

9-09 3,".4> 3J--S6

(6)

TRANSIT OF VENUS, 1874. APPENDIX.

Greenwich
Sidereal Time
on Dec. 8.

R. A.

of Sun.

N. P. D.
of Sun.

R. A.

of Venus.

N. P. D.
of Venus.

Green wicli
Sidereal Time
on Dec. 8.

R. A.

of Sun.

N. P. D.
of Sun.

R. A.
of Venus.

N. P. D.

of Venus.

0 /

n

o /

0 /

o /
ir

o /

o t
it

o /

o /

h m

h m

255. 56.

112.49.

255. So.

112. 34.

255. S6.

112.49.

255. So.

112. 33.

II. 30

29-82

41-53

46-60

4-25

11.40

57-20

43-98

30-98

56-32

3i

32-56

41-78

45-04

3-46

4'

59-94

•44-23

29-42

55-53

32

35-3o

42-02

43-48

2-67

42 62-68

44-47

27-86

54-74

33

38-o3

42-27

41-91

1-87

43

65-41

44-72

26-30

53-94

34

40-77

42- Si

40-35

I -08

44

68-iS

44-96

24-73

53-i5

255. 56.

112.49.

255. So.

H2.33.

255. 57.

112.49.

255. So.

H2.33.

H.35

43 -Si

42-76

38-79

60-29

11.45

10-89

45-21

23-17

52-36

36

46-25

43-00

37-23

59-49

46

13-63

45-45

zi' 61

5i-56

37

48-99

43-25

35-67

58-70

47

16-37

45-70

2O'OS

So- 77

38

Si-72

43-49

34-10

57-91

48

19-10

45-94

18-49

49-98

39

54-46

43-74

32-54

57-I2

49

21-84

46-19

I6-93

49-18

255. 57.

112.49.

255. So.

112. 33.

II. So

24- 58

46-43

iS-36

48-39

Semi-
diameter
of Sun.

Parallax
of
Sun.

Semi-
diameter
of Venus.

Parallax
of
Venus.

Semi- .
diameter
of Sun.

Parallax
of

Sun.

Semi-
diameter
of Venus.

Parallax
of
Venus.

1 6'. 1 6" -82

9" -09

3i"-42

33"- 86

16'. i6"-82

9"- 09

3i-42

33"- 86 .

TABULAR PLACES OP SUN AND VENUS. SPECIMENS OF SKELETON FORMS. (7)

APPENDIX IV.— SPECIMENS of the SKELETON FORMS Nos. 17, 18, 19, 20, used in the
COMPUTATION of the FACTORS in the FINAL EQUATION formed from each OBSERVATION
of INGRESS or EGRESS.

(8) TRANSIT OF VENUS, 1874. APPENDIX.

[FORM No. 17.]

Station

BRITISH EXPEDITION FOR THE OBSERVATION
Latitude Log. Normal-centric Radius

Local
Ordinal

No.

Observation.

Times.

Tabular H. A. of

Observer.

Phenomenon
or
Measure.

Name of
Clock
or
Chrono-
meter.

Time by
Clock
or
Chrono-
meter.

Local
Sidereal
Time.

Greenwich
Sidereal
Time.

Geoc. E. A.
of O

of 5

Excess for J

Parallax
in R. A.

of©

of 5

Exc. for £

•

0

,.

1

2

a

4

5

6

7

8 .

9

Each Chief of Station, or Observer, is requested to place his signature under the Columns of Observations and

SPECIMEN OF FORM No. 17.

(9)

[PAGE

OF THE TRANSIT OF VENUS, 1874.
Log. Axial Distance

Assumed W. Longitude

Sun and Venus.

Tabular N. P. D. of Sun and Venus.

Tabular Local
Distance of Centers.

Local R. A.
of©
of 5
Excess for £

Incr. of R. A.
in 1s

of ©

of 5

Excess for 5 .

Geoc. N.P.D.
of©
of 5
Excess for $ .

Parallax
in N. P. D.
of©
of $
Excess for 5

Local N.P.D
of©
of $
Excess for §

Incr. of
N. P. D.
in I'
of©
of J
Excess for 5

Local
Distance
given by
Tabular
Elements.

Incr. of Dist.
in 1'
and for
•r^r incre. of
Parallax.

•

•

10

11

12

13

14

is

16

17

Times, and each Computer is requested to place his signature under the calculations for which he is responsible.

3v

(10)

[FORM No. 18.]

TRANSIT OF VENUS, 1874. APPENDIX.

[PAGE

BRITISH EXPEDITION FOR OBSERVATION OF THE TRANSIT OF

VENUS, 1874.

COMPUTATION OP NORMAL-CENTRIC ELEMENTS.

(The surface of a concentric sphere being supposed to touch the equator, and a line normal to
the equatoreal plane being drawn through the observing station to the surface of the sphere ; its
intersection with the surface of the sphere is the " corresponding point ;" and the latitude, on the
sphere, of that point is the " corresponding latitude."

The normal to the spheroidal surface at the observing station, being produced to intersection
with the earth's axis, is the " Normal-centric radius ;" the place of that intersection is the " Normal
Center," always in the hemisphere opposite to the hemisphere of the station ; the distance of that
intersection from the Earth's Center, measured along the earth's axis, is the " Axial Distance of
Normal Center.")

o / //

o / //

o / //

Log 299 Lo«~ 300

9,99855

9,99855

9 99855

° / //

0 / //

0 / //

>

7 82391

7 82391

J

NOTE. — Angles are to be taken to the nearest 10".
Logarithms to 5 decimal places.

Computer's signature.

[FORM No. 19.]

SPECIMEN OF FORMS, Nos. 18 AND 19.

[PAGE

(11)

BRITISH EXPEDITION FOR OBSERVATION OF THE TRANSIT OF

VENUS, 1874.

CALCULATION OF TABULAR PARALLAXES IN R.A. AND N.P.D. BY NORMAL-CENTRIC METHOD.

Station . Latitude N.S.

Log. Axial Dist. of Normal Center ,

. Log. Normal-centric Radius ,
Tab. hor. eq. parallax, for Q > , for

Obs. No. (17), E.W. of Merid.

Object.

Sun.

Venus.

Sun.

Venus.

Sun.

Venus.

h m 8

ti m e.

h m M

h m s

h m s

h in b

Multiply by 60, divide by 4

•

•

.

o / //

° f //

u / //

9 / //

0 / //

0 lit

Tab H A of object (17) . ...

"

'

* *

"

*

•

Tab. N.P.D. of object (17) ....

•

•

.

.

" "

)

»

*

*

)

*

>

1

>

*

*

*

Log N C Radius

*

1

1

Log. tab. hor. eq. parallax . . .

»

,

t
t

)

Sum = log. Parallax in E.A. . .

»

>

,

»

J

,

Parallax in R.A. ( + if E.)

»

r/

j

>

//
i

//
)

/'

i

'

*

*

*

>

*

'

*

i

1

*

i

H

p.D.

" "

• •

'

7 — P D &

•

*

* *

• •

• •

•

*

»

'

>

J

>

Log. N.C. Radius

»

1

>

»

>

Log. tab. hor. eq. parallax . . .

,

,

>
>

*

i

Sum = log. par. (1) in P.D

•

.

J

j

)

,

Log. Axial Dist. of N.C

•

>

>

1

»

Log. tab. hor. eq. parallax . . .

1

»

)

>

j

>

J

>

Sum = log. par. (2) in P.D. . .

)

i

,

*

1

,

Parallax (1) in P.D

''

//

//

//

//

Parallax (2) in P.D

*

>

t

>

'

'

1

>

Sum = Total Parallax in P.O..

>

»

t

>

9

9

Parallax in N.P.D

9

*

9

>

NOTE. — Time is to be taken to the nearest 1'.

R.A. in arc, hour-angle, P.D., o, 0, y, to the nearest 10".
Logarithms to five decimals.
Parallaxes to 0" -01.

Computer's signature.

3y 2

(12)

TRANSIT OF VENUS, 1874. APPENDIX.

[FORM No. 20.] [PAGE

BRITISH EXPEDITION FOR OBSERVATION OF THE TRANSIT

OF VENUS, 1874.

COMPUTATION OF TABULAR LOCAL DISTANCES BETWEEN THE CENTERS OF THE SUN AND
VENUS, AND OP FACTORS OP CORRECTIONS TO TIME, R.A., N.P.D., AND PARALLAX.

(The quantities are entirely Tabular Local quantities. " Excess of R.A." always denotes "Excess of Tabular
Local R.A. of the Center of Venus above that of the Sun." " Excess of N.P.D." always denotes " Excess of Tabular
Local N.P.D. of the Center of Venus above that of the Sun." " Parallax " [meaning Horizontal Equatoreal
Parallax], " Parallax in R.A.", " Parallax in N.P.D.", always denote " Excess of those quantities for Venus above
the similar quantities for the Sun." The same applies to the several " Increases." The S.P.D. of Sun and Venus
are, however, absolute values. " Distance between Centers " denotes " Tabular Local Distance between Centers."
All logarithms are to be taken to five decimal places. To six places for " Distance between Centers.")

Station.

No. of Observation in Form 17.

S.P.D. of Sun (to 10") . .
S.P.D. of Venus (to 10") .

Excess of Right Ascension (to 0"-01) (+ near beginning, — near end)
Increase of Excess of Right Ascension in 1". (to 0"-001) (always — ). .

Excess of North Polar Distance (to 0"- 01) (always -)

Increase of Excess of North Polar Distance in 1". (to 0"' 001) (always — )

Parallax in R.A. . .
Parallax in N.P.D.

Computation of Tabular Local Distance of Centers of Sun and Venus.

Log. sine of S.P.D. of Sun . .
Log. sine of S.P.D. of Venus

Sum

Half Sum (always + )

Log. Excess of R. A. ( + near beginning, - near end)

Sum = f (sign same as for Excess of R.A.)

Subtract log. Excess of N.P.D. with sign changed (always + )

Log. tan. <t> (sign same as for Excess of R.A.)

<l> (to 10") (less than 90°, sign same as for Excess of R.A.)

Log. sine <f> (sign same as for Excess of R.A.) .
Subtract from f (sign same as for Excess of R.A.) .

Log. Distance between Centers (always + )

Log. cosine </> (always + )

Subtract from log. Excess of N.P.D. with sign changed (always + )

Log. Distance between Centers (always + )

Distance between Centers (to 0"-01).
(Continued on 2nd page.')

SPECIMEN OF FORM No. 20.

(13)

{Continued from 1st paye.)

Effects of Changes of R.A., of N.P.D., and of Time, on the Distance
between Centers.

Half Sum (above) + ,

Log. sine <t> (above)

Sum = log (

f = Factor of Change of R.A. for Distance between Centers (si<m as 1
for Excess of R.A.) ......./

Log. Increase of Excess of R.A. in 1'. (always — )

Sum with log. f = log. it ( — near beginning, 4 near end)

rj (to 0"-0001)

Log. cosine <t> (above)

Nat. cos. q> = Factor of Change of N.P.D. for Dist. betw. Cent, with 1
sign changed (always — )

Log. Increase of N.P.D. in I1, (always — )

Sum with log. cos. <t> = log. 9 (always +) +

flto(0"-0001)

1

TI + 8 = Increase of Distance between Centers in I1

Effect of Change of Coefficient of Parallax on the Distance
between Centers.

Log. ( (above)

Log. -j-^j Parallax in R.A

Sum = log. «

K (to 0 • 0001 )

Log. cos. <t> (above) with sign changed

Log- -nhr Parallax in N.P.D

Sum = log. A

\ (to 0-0001)

K

« + \ = Increase of Distance between Centers for -i_ Increase of!
Parallax ° _ j-

Signature of Computer.

(14) TRANSIT OF VENUS, 1874. APPENDIX.

APPENDIX V. — PHOTOGRAPHIC OBSERVATIONS of the TRANSIT of VENUS.

The apparent uncertainty in the conclusions from the photographic registers has led extensively
to the persuasion that it is unnecessary to record the photographic operations with the utmost
detail. But it appears proper to explain the views which directed the order of reductions, and to
describe the instruments which have been employed.

The photoheliograph instruments in every case were mounted equatoreally, and it is probable
that their adjustments were, as for ordinary uses, reasonably accurate. But it is impossible to place
so much confidence in these adjustments, or in the insertion of the photograph-plate in the tube,
as to justify the supposition that differences of R. A. and of N. P. D. between the Sun and the
Planet could be measured with even moderate accuracy. The only measure upon which reliance
could be placed is that of the distance between the centers of the two objects. Relying on the
practicability of putting the plates fairly in position for that measure (extreme accuracy in this
adjustment is not indispensable) it was only necessary to provide means of measuring accurately
in one direction.

The principle of the micrometer here adopted is the following : — Two microscopes, both pointing
downwards, pass through a very firm bar, 15 inches long ; the tubes of the microscopes being
separated about 11^ inches. (The bar, in fact, is not a solid piece of metal, but is formed like a
box, with sides 2| inches deep, and is free f'rotn sensible flexure under any ordinary strain.) The
two microscopes, in this state, form a microscopic beam-compass. The beam-compass can be slid
endways, with a range of nearly 8 inches, in an intermediate frame about 23 inches long, to which
it can be clamped at any part of its motion ; practically, however, the clamp was not used.
That intermediate frame has a slot or chase extending nearly from end to end, through which the
microscopes, and the bar which carries them, pass. The intermediate frame itself can be moved
endways (carrying with it the beam-compass) upon the upper face of the fixed stand, by means
of a fine screw at one end, carried by the fixed stand ; the range of this screw is less than 1 inch.
The upper part of the fixed stand is a strong plate, 24 inches long, slotted nearly from end to end,
in the same manner as the intermediate frame ; and the 'beam-compass slides endways through
the slot of the intermediate frame and through the slot of the upper part of the fixed frame at the
same time. The upper part of the fixed frame is earned by pillars 3 inches long fixed to tke
base-plate. The base-plate is 24 inches long and 7 inches broad, and it has two longitudinal
perforations each about 9 inches long and 3 inches broad, with an intervening metallic cross-bar
2 inches in breadth. One of the microscopes always points downwards to one of these perforations,
and the other microscope to the other perforation. The wooden structure which carries the
base-plate has corresponding perforations. In use, the wooden structure is so planted above a
mirror that the light of the sky is reflected upwards through the microscopes. The microscopes
are now in a fit state for observing transparent objects which are laid upon the base-plate.

Over one of the perforations of the base-plate is laid the photograph, of which measures are to
be taken. On the method of placing this photograph we shall speak shortly. The microscope
which views the photograph, and which we shall call the " photograph-microscope," lias a crossed
wire, fixed in the field of view.

On the other perforation of the base-plate there is placed, in a, receptacle adapted to its form,
the " millimetre scale ; " a scale etched on glass, graduated to 240 millimetres ; its length is parallel
to the length of the beam-compass. The microscope which views the scale, and which we shall
rail the " scale-microscope," has the usual cross-wires carried by a micrometer-screw.

INSTRUMENTS FOR MEASURE OF PHOTOGRAPHIC REGISTERS. (15)

This combination evidently possesses the power of measuring the distance of any part of the
photograph from some part of the millimetre scale, subject to a constant correction ; and therefore
possesses the power of measuring the distance between any two parts of the photograph.

We now proceed to the verification of the sub-divisions of the millimetre scale. A second
millimetre scale is provided, similar to the first, but containing only 64 millimetre spaces. By
placing this secondary scale in different positions under the photograph-microscope, we can use
different portions of the principal scale to measure the whole or any part of the secondary scale.
Thus, adopting as fundamental divisions of the principal scale the Nos. 20 and 148, we could use
both the spaces 20 — 84 and 84 — 148 for comparison with the whole length of the secondary scale,
and thus could find the relative error of division 84. This being established, we can adopt half
the length of the secondary scale, and can use with it the spaces 20—52 and 52 — 84 for the error
of 52, and the spaces 84 — 116 and 116 — 148 for the error of 116. This process of bisection was
carried on, with an extension for the first and last numbers of the scale, till the error of every
graduation was determined.

The photographic plates were mounted in the measuring apparatus by the following arrange-
ment : — The glass plates for the British Expedition were each 6 inches square ; those for the
Australian photographers were 6| inches square. Circular brass plates of sufficient thickness
were prepared ; that for the British photographs was lOf inches in diameter, and that for the
Australian photographs 12^ inches in diameter. These plates were pierced with square holes,
fitted to receive the photographic glass plates, and having ledges and 'springs for supporting and
steadily holding them. The brass-plate was laid upon the base-plate of the micrometric instru-
ment and pushed in laterally between two guides as far as was necessary, and was held steady
by a spring. As the brass plate could be turned to any position in azimuth and could be pushed
in to any extent, there was no difficulty in adjusting the direction of the line to be measured so
as to make it coincide with the line of the beam-compass. For so adjusting the line joining the
centers of the Sun and Venus a moveable wire-frame was provided : carrying a central wire ; a
wire on each side parallel to it, at a distance very approximately equal to the radius of Venus ; and
a wire on each side at a distance very approximately equal to the Sun's radius. The wires were
made tangentially to touch the two images ; marks for the center wire were made on the brass
plate at the place of the central wire ; and the adjustment on the base-plate was made with great
facility.

I now proceed to explain the use of the instrument for determining the distortion of images
formed by the photoheliograph.

Some years ago, Mr. Warren De la Rue constructed for a special purpose a scale of equal parts,
15 feet in length. The frame of this scale consists of three iron tube-columns, each 15 feet long,
and % inch in diameter, braced together with diagonal bracings, so as to form a triangular prism
15 feet long with sides (center to center) about 12| inches apart. To one side of the prism are
fixed eight iron plates, each 2 feet broad in the direction transverse to the length of the frame and
1 foot broad in the direction of the frame's length, with intermediate spaces of 1 foot each : it is
this succession of plates and spaces which constitutes the scale of equal parts. The whole is
beautifully worked. This instrument is (by Mr. De la Rue's kind permission) now preserved in
the Royal Observatory.

Our first requirement was, to satisfy ourselves, by our own examination, that the spaces are
equal, with insignificant error. For this purpose, a curtate triangle (1) was prepared, whose sides
approach at the ratio of 1 approach to 12 length of side ; and another frame (2) adapted to embrace

(16)

TRANSIT OP VENUS, 1874. APPENDIX.

the curtate triangle in its whole height, as nearly as possible. These " trammels," as we called
them, are made of sound hard oak wood, with the utmost care that carpenters could give. Definite
corresponding points were adopted as those which represent very approximately on both trammels
the interval 12 inches. With trammel (1) all the intervals between the plates were measured at
both their extremities ; and with trammel (2) the breadth of every plate was measured at the
same parts. Some numerical differences were thus ascertained, totally insensible in the further use
of the scale.

The scale, thus verified, was fixed above the north balustrades on the top of the Octagon Room
of the Royal Observatory. By permission of the Governor of the Royal Naval College, a photo-
graph-observatory was erected in the court of the Naval School, at a distance from the Royal
Observatory (perhaps 1,500 feet) which permitted the image of the scale to occupy the greater
part of tiie photographic plate when inserted in each of the photoheliographs. To this photographic
hut was brought, in succession, each of the five heliographs used in the Transit Expedition ; and
images of the scale were taken, in exactly the same way as the images of the Sun with Venus in
the Transit. The photographs were then inserted in the micrometer-apparatus, and were measured,
for both edges of each plate of the scale. The further treatment of these measures will be best
understood from the inclosed specimen of Form 22. The words and figures in italic type are
copied from a real observation. It is to be remarked that five revolutions of the micrometer
correspond very nearly to one millimetre.

It will be seen here that the amount of distortion is considerable. Observations were made
with the tubes of the photoheliographs turned in different positions or "azimuths" round the
optical axis of the telescopes, but no certain difference of distortion could be ascertained.

The total number of sheets of Form 22 is about 300. The numbers (for each instrument) for
" Excess of De la Rue's Scale" were collected from the different sheets, the means for (16) — (1),
(15) — (2), &c., were taken, and the results were laid down in separate curves for the five
instruments. These curves were smoothed down, and their ordinates were used to give corrections
for the measures of the Transit Photographs.

The following are the Corrections thus obtained by Major Tupman, applicable to the Readings
in the several series of Photographs : —

Distance
from Center.

Corrections to the Readings in the several series of Photographs.

Honolulu.

Mokattam.

Rodriguez.

Kergnelcn.

Burnbam.

mm-

mm.

mm.

mm.

mm*

„„„.

3o

+ -o63

+ '070

+ '080

+ -074

+ -076

3l

+ -062

+ -068

+ '078

+ "072

+ -°74

3i

+ '060

+ '066

+ -076

+ '070

+ '071

33*

+ 'oSy

+ -064

+ '°74

+ '067

+ -068

34

-r 'OSS

+ -062

+ '0/1

+ -064

+ -o65

35

+ -o5z

+ -o5g

+ '067

+ -061

+ '061

36

+ -049

+ -o56

+ -o63

+ -o58

+ -o57

37

+ -046

+ -o53

+ -059

+ '054

+ -o53

38

+ '042

+ '°49

+ -054

+ -o5o

+ '°49

39

+ -o38

+ -045

+ -oSo

+ '046

+ -04.5

CORRECTION OF MEASURE OF PHOTOGRAPHS FOR DISTORTION.

(17)

Distance
from Center.

Corrections to the Headings in 'the several series of Photographs.

Honolulu.

Mokattam.

Rodriguez.

Kerguelen.

Burnham.

4°

+ 'o34

+ '040

+ -045

+ "042

+ '040

41

+ -o3o

+ -o35

+ 'o3g

+ -037

+ -o35

42

+ -O25

+ -o3o

+ -o33

+ -o32

+ -o3o

43

+ 'O20

+ '025

+ '027

+ -027

+ 'O25

44

+ -oi5

+ '019

+ 'O2I

+ -02 1

+ '02O

45

+ 'OIO

+ -012

+ '014

+ 'oi5

+ -014

46

+ -oo5

+ '006

+ '008

+ -009

+ '007

47

— 'OOI

•ooo

+ 'OOI

+ -oo3

•ooo

48

— -007

— '006

— '006

- -oo3

— '006

49

- -oi3

- -oi3

— 'OI2

— 'OIO

- -oi3

So

— -019

— -021

— -O2O

- -017

— 'O2O

5i

— '026

— -029

- -028

— '024

- -028

52

- "032

- -o37

- -o36

- -o3i

- -o36

53

— -039

— '045

- -°44

- -o38

- '°44

54

— '045

- -o53

- -o52

— -046

- -o52

55

— -o5z

— '061

— '060

- -o53

— '061

56

— 'oSg

— -069

— -069

— '061

— '070

57

- -066

- -078

- -078

— -069

- -°79

58

- -°74

- -087

- -088

- -077

- -088

59

- -082

— '096

- -098

- -086

- '°97

60

— '090

- M05

- -108

- '°94

— -106

61

- -098

- -u5

- -118

- -io3

- -n5

62

— • 106

- -124

- -128

— -112

- '125

63

- -114

- -i33

- -.39

— • 121

- -i35

64

— -122

- -i43

- -i5i

- -i3o

- -I45

65

- -i3i

- 'l52

- -162.

- -i39

- -i56

66

— • 140

- -.62

- -174

- -148

- -167

67

- -149

- -172

- -i85

- -i57

- -178

68

- -i58

- -182

— • 196

- -166

- -189

69

- -168

— '192

- -208

- -i75

— '2OO

70

- '177

— '2O2

— -2ZO

- -i85

— -aio

In the application of these correctio.ns to the measures in Form 21 (see the specimen of that
Form) there is a small theoretical doubt, depending on the different focal adjustments of the
photoheliograph when used on Ue La Rue's Scale and when used in the Transit. The easiest
method of adjusting to focus is by motion of the object-glass ; and in that case (see a short

3z

(18) TRANSIT OF VENUS, l8?4. APPENDIX.

investigation in the "Observatory," No. 16, Vol. ii., p. 122) the correction found from tiit-
observation of the Scale is justly applicable to the photographs of the Transit. It is believed that
this mode of adjustment was always employed ; and the corrections adopted in the use of Form 21
are made on that principle. If, however, the adjustment were made by altering the place of the
photographic plate, a different correction would be required.

The method of so placing the photograph-plate that the centers of the Sun and Venus would
be in the longitudinal line of the measuring apparatus has been described. The crossed wire of
the photograph-microscope can then be placed upon the 1st limb of the Sun, the 1st limb of Venus,
the 2nd limb of Venus, and the 2nd limb of the Sun. The further treatment of the photographs
will be understood from the inclosed specimen of Form 21. The line " Correction for difference
of irradiation " was, in fact, never used.

In some instances, the definition of the limb of Venus was not satisfactory. In particular, in
the earlier observations at Mokattam (where the Sun rose with Venus on his disk) some of the
images of the planet were much distorted. To obviate this, Major Tupman caused to be prepared
a glass diaphragm, on which was engraved a circle somewhat smaller than the disk of Venus, and
also crossed lines similar to the usual crossed wires ; and measures were taken for comparing the
place of intersection of the wires with the center of the circle.

The number of sheets of Form 21 employed in calculation is about 440. A portion of the
measures was made by Major Tupman ; the greater part, however, by Mr. Burton : no other
observer was employed on them.

The clock-time of every exposure of the photoheliograph- plate for image having been noted,
this time was converted into Greenwich Sidereal Time, the tabular distance of centers was com-
puted, and the factors of the various possible errors (S n, 8 R.A., 8 N.P.D, 8 1, 8 R, S r) were
formed, by the use of Forms 17, 18, 19, 20, exactly as for the eye-observations. The comparison
of each of these tabular lines with the distance of centers found in Form 21 gave an equation.
These equations were most carefully grouped by Major Tupman ; and solved, by the use of proper
factors, in the form most favourable to accuracy.

After laborious measures and calculations it was thought best to abstain from publishing the
results of the photographic measures as comparable with those deduced from telescopic view.
The considerations which led to this decision are stated by Major Tupman in a paper in the
Monthly Notices of the Royal Astronomical Society, volume 38, page 508 (1878, Supplementary
Notice). They are mainly embodied in this : that, however well the Sun's limb on the photograph
appeared to the naked eye to be defined, yet on applying to it :i microscope it became indistinct
and untraceable, and when the sharp wire of the micrometer was placed on it it entirely
disappeared.

A great number of photographs (216 in all) have been received from the following stations,
and are entered in Form 21: — From India: Roorkee, 91. From Australia: Sydney, 60;
Melbourne, 29 ; Woodford, 20 ; Eden, 16.

APPARATUS FOR RAPID FORMATION OF PHOTOGRAPHS. (19)

When the preparations for the Transit Expedition were far advanced, a proposal was published
by M. Janssen for taking a photograph of Venus and a portion of the Sun's limb near to it at
every second of time, or other short interval, near to the times of ingress or egress. It appeared
desirable to make trial of this proposal ; and, under my general superintendence, an apparatus
was prepared by Mr. Dallmeyer, with great skill, which appeared likely to carry out M. Janssen's
proposals perfectly well. A circular photographic glass plate, lOf inches in diameter, mounted
in a large ring whose circumference was cut in teeth, was so arranged that, when its frame was
fixed upon the photographic end of the photoheliograph, with the photographic plane transversal
to the optical axis of the instrument, it could be made to rotate by a small toothed-wheel spindle
(whose axis was parallel to the optical axis), but not continuously. During a portion of the
rotation of the spindle the large ring and photographic plate stood still ; and the plate was exposed
to the Sun, and an image was formed. (This was effected by cutting away some of the spindle-
teeth.) During the remaining portion of the rotation the sun-light was stopped, and the motion
of the spindle gave motion to the ring and plate so as to expose a new part for a new photo-
graphic image. The winch by which the spindle was turned was very near the center of motion
of the great tube ; and it was found that, when turned by a careful hand, no tremor could be dis-
covered in the photographic apparatus. The photographic images were to be measured by due
adaptation of the photograph-micrometer.

The number of images thus taken and entered in Form 21 was: — At Thebes, 83; at Rod-
riguez, 146 ; at Roorkee, 53. But they have not been further reduced. The ardour of the
Observers had been much cooled by the apparent general failure of the photographic principle,
and they were unwilling to spend further time on these reductions.

1881, June 10. G. B. AIRY,

4A

(20)

TRANSIT OF VENUS, 1874. APPENDIX.

[FORM 22.]

BRITISH EXPEDITION FOE OBSERVATION OF THE TRANSIT OF VENUS, 1874.
MKASUBES of the PHOTOGRAPHS of the DE LA RUE SCALE.

Reference to distinctive marks on the photograph .

Plate 297, C. Instrument.

Photographer, and time of photogra

Burton. 1873, August 25.

Burton. -1875, October 18.

Whether at upper edge, center, or lo

Upper.

Set 2.

r
Correction for error of runs on 5 of micrometer . . .

+ 0-0195.

Part measured.

1st Micr.
Reading.

2d Micr.
Reading.

Mean.

Core, for Div.
Error.

Corrected
Reading.

Corr. for Runs.

("first edge (1)

mm. r
151. 2-630

-142. 3-276
133. 3-89$
124. 4-716
116. 0-610
101. -1-6S3
98. 2-794
89. 4-052
81. 0-329
72. 1-493
63. 2-563
54. 3-619
45. 4-323
37. 0-280
2$. 0-830
19. 1-681

r

2-629
3-337
3-902
4-751
0-651
1-756
2-812
3-905
0-314
1-432
2-626
3-622
4-280
0-284
0-831
1-131

mm.
151-5259

142-6613
133-7800
124-9467
116-1261
107-3439
98-5606
89-7957
81 • 0643
72-2925
63-5189
54-7241
45-8603
37-0564
28-1661
19-3412

mm.

f + -0080 \
1 + -0103 J
f + -0132 \
1 + -0129 J
( + -0136 \
\ + -0152 J
/ + -0140 \
\ + -0185 J
/ + -0106 1
\ + -0025 J
( + -0075 1
\ + -006S J

r + -0092 \

\ + -0109 J
f + -0131 \
\ + -0-156 J
f + -0085 \
1 + -00^3 J

r + -0120 \
\ + -0057 J"
{+ -0064 1
+ -0^02 J
f + -0059 "1

1 + -0*42 /

/ + -0^34 1
\ + -0168 J
J + -0299 1
1 + -00^7 J
!+ -0092 1
+ -0033 J
+ -0100 \
+ -0067 J"

mm.
151-5442

442-6874
133-8088
124-9792
116-1392
107-3582
98-5807
S9-8250
81-0741
72-3102
63-5355
54-7442
45-9005
37-0874

2S-1786
19-3579

Plate 1 -1

("first edge (3)

Plate 2 -j

{first edge (5)

(" first edge (7)

Plate 4-^

("first edge. (9)

Plate ^

f first edge (11)

Plate 6 -j
|_second edge (12)

("first edge (13)

Plate 7 i
|_ second edge (14)

f first edge (15)

Plate 8 1

COMBINATIONS of the CORRECTED READINGS, independent of ZERO and CENTER-MEASURE.

Quotient Corresponding Quantity
Ranges, and their Measures. of each Measure on De la Rue's
by the Sum. Material Scale.

Excess of
De la Rue's Scale.

(16) - (1) 43S-4663 0-2349000 0-2343800
(15) - (2) 114-50$$ 0-2034864 0-203/357
(14) - (3) 96-7214 0-1118115 0-1118875
(13) - (4) 79-0~87 0-1405258 0--1406142
(12) - (5) 61-3950 0-109-10-12 0-1093703
(11) - (6) 43-8227 0-0778746 0-0131198

(10) - (7) 26-2105 0-0466837 0-04687-IO
(9) _ (g) 8-7509 0-0155501 0-0156215

- 0-0005200
- 0-0003507
+ 0-0000-100

+ 0-0000884

+ 0-0002691
+ 0-0002452
+ 0-0001873
+ 0-0000708

Sum 562-7343

0-9999999

Signature of Computer, IJ.D.

REMARKS : Azimuth of Scale

t

SPECIMENS OF FORMS 22 AND 21.

(21)

[FORM No. 21.]

BEITISH EXPEDITION FOE OBSERVATION OF THE TRANSIT OF VENUS, 1874.
MEASURES of SOLAR PHOTOGRAPHIC IMAGES made with the PHOTOHELIOGRAPH.

Station, Keryuelen.

Register Mark upoii the Photograph Plate, 8.

h m I

Other Registers, G. S. T., S. 59. 27 • 7-

No. of Photograph in Form No. 17.

Approx. Micr. Reading for 1st edge, center, 2d edge
Correction for Runs of Micrometer for 5 revolutions

, of Phot. Field.
+ 0- 0<

mm. mm.

; ^ $7-0;
164 and 0- 1034.

Micrometer Measures of Limbs of Sun and Venus.

Order of Measures.

1st Limb of
Sun.

1st Limb of
Venus.

2d Limb of

Venus.

2d Limb of
Sun.

18~6.
n

mm.
31

2-169
2-232

2-288

3-342
3-239
3-174

mm.
123

4-940
4-949
5-004
126
1-354

1-269
1-240

mm.

129

1-731
1-663
1-604

3-142
3-224
3-194

mm.

134

0-414
0-442
0-370

1-993
1-980
2-049

Feb 11 .. <2

[3

f"4

Feb 12. \ 5

u

Sums

16-444

33-756

14-538

7-248

mm.
31-54$-l

+ 0-0132
+ 0-0110

mm.

126-1252

+ 0-0132
+ 0-0025

mm.

129-4S53
+ 0-OOS3
+ 0-0097

mm.

134-2416

+ 0-0132
+ 0-0048

Apply mean correction for Division Error "1
and Huns J

Apparent Means corrected for Division"!

31-5743

+ 0-056

126 • 1409
+ 0-046

129-5033
+ 0-030

134-2596
+ 0-001

Correction for distortion

Means finally corrected

(1) 31-630

(2) 126-187

(3) 129-534

(4) 134-261

Repeat (1) under (4), and (2) under (-3) ...

(2) 126-187

(1) 31-630

.;.;•/,

39-1

42-3

47-3

Computation of the Distance of Centers of Sun and Venus.

Tabular Quantities.

Measured Quantities.

i
Diameter of Sun 193*.

f

1-62
>-$4

(4) -(!) = Diameter of S
(3) - (2) = Diameter of "
Sum. .

mm.
5un 102'631

Diameter of Venus 6i

Penus 3-347

Sum of Tabular Diameters 2016 • A6

103-07$

Its logarithm (5) 3-30*

,590
"215

Correction for difference of irradiation . .
Corrected sum of Measured Diameters . .

.. - o-

Subtract log. sum of Meas. Diameters . 2' 02i

..

375
'239

(4) + (1) = double reading for Sun's center. 165-891
Sub. (3) + (2) or double reading for ? center 255- 721

Add log. Distance of centers in mm. . 1-6i

Double distance of centers in mm

89-830

Distance of centers in m

m 44-915

Log. Meas. Distance of centers in arc. 2-9i
Adil log. 2 0-3(

H77
)103
)541

Measured distance of cen
Number = Factor of (S

ff
ters in arc 34 • 61

Add ar. co. (5) 6-6<

Sum 9'9i

'821

Kemarks. — The center of field 6"""- below the common diameter of Venus and Sun.

(Signature of Measurer of Photograph), C. E. BURTON.
(Signature of Computer), H. P.

\

LONDON:

Printed by GEOKGE E. EVBE and WILLIAM SPOTTISWOO'JE,

Printers to the Queen's most Excellent Majesty.

For Her Majesty's Stationery Office.

[17091.— 750.— 7/81.]

\

Rl
T<

1

ff

JIT

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