TEANSIT OF VENUS, 1882.
Report of the Committee appointed by the British
Government to superintend the Arrangements
to be made for the sending of Expeditions at the
Government expense, and securing co-operation
with the Government Expeditions for the
Observation of the Transit of Venus, 1882,
December 6.
P? ^ TRANSIT OF VENUS, 1882.
Report of the Committee appointed by the British Government to superintend the
Arrangements to be made for the sending of Expeditions at the Government
expense, and securing co-operation with the Government Expeditions for the
Observation of the Transit of Venus, 1882 December 6.
A Committee was appointed by the Royal Society in 1881 for the purpose of
:, advising the Treasury and the Admiralty with respect to the conduct of the Transit
•C v of Venus Observations in 1882. Their Report was printed as a Parliamentary Paper
in October 1881.
po The Committee of recommendation considered it undesirable to undertake photo-
i graphic observations of the transit with the instruments and methods which had been
^ adopted in 1874, and that the time at disposal before the date of the transit was
^ insufficient to allow experiments to be undertaken of methods which might promise
greater chance of success, and the construction of any instruments which might be
^, found necessary to carry out such observations, and recommended that attention should
<* be chiefly directed to "contact" observations.
^ The adoption of this method would also render available valuable co-operation on
^ the part of the numerous experienced and well-equipped observers, both amateur and
professional, who were scattered over Australia, New Zealand, Canada, Cape of Good
Hope, and Mauritius, all of which Colonies afforded most important stations for the
observation of the contacts for the purpose of determining the Sun's distance.
It would therefore only be necessary to send out expeditions to a small number of
stations, which were otherwise insufficiently provided for, in order to secure, if the
atmospheric conditions were generally favourable, a number of contacts sufficiently
great to allow of a value of the Sun's distance, with some pretensions to precision, to
be thus obtained.
An Executive Committee was appointed by the Government in 1881 to carry out
these recommendations.
The following stations were occupied by expeditions sent directly from England :
Jamaica,
Barbados,
Bermuda,
Montagu Road, Cape of Good Hope,
Madagascar,
New Zealand,
Brisbane,
and an additional equatoreal was sent to the Cape Observatory, and two equatoreals
for the equipment of a station at Aberdeen Road, Cape of Good Hope, for which
observers were supplied from the staff at the Royal Observatory, Cape of Good Hope.
The observations at all of these stations were successful, with the exception of
Brisbane, where the observations were rendered impossible by dense cloud and rain ;
and the observations at these stations were supplemented by observations at —
Natal,
Mauritius,
Australia,
New Zealand, and
Canada,
which have been directly forwarded to the Committee, and discussed in the following
Report.
A "Draft of Instructions for the Observers" was issued by the British Executive
Committee for consideration and discussion in October J 881. This draft was taken
into consideration at an International Conference held in Paris in October 1881, and
a set of instructions substantially founded upon it was issued, which it was hoped
might secure uniformity in the observations. These instructions were supplemented
by a set of instructions issued by the British Committee, which were freely distributed
in the Colonies, and observers who were provided with instruments of sufficient power
to enable them to take a part in the observations with any reasonable prospect of
success were invited to co-operate.
In framing these " instructions " it was considered that the chief difficulties to be
feared in attempts to deduce an accurate value of the Sun's distance from contact
a 22653. Wt. 4764. A
observations were those connected with the possibility that the recorded times for
internal contact might refer to phases which take place with different angles of
separation of the limbs; and it was expected that by directing the attention of
observers to this difficulty, and by securing, if possible, a considerable number
of observations, the mean phases observed for " transit accelerated" would be sensibly
the same as that for "transit retarded," which is all that is required for the
determination of an exact valine of the Sun's distance from a discussion of such
contact observations.
It will be seen from the results obtained that these expectations have to a great
extent been realised.
Personnel.
The British expeditions sent out from England consisted of the following : —
To Jawiaica. — R. Copeland, Ph.D., Chief.
Oapt. Mackinlay, R.A.
Bermuda, — J. I. Plummer, M.A., Chief.
Lieut. Neate, R.N.
Barbados. — C. G. Talmage, Chief.
Lieut. Thomson, R.A.
Montagu Road, Gape Colony. — A. Marth, Chief.
CM. Stevens (joined from Cape Civil Service).
Madagascar. — Rev. S. J. Perry, F.R.S., Chief.
Rev. W. Sidgreaves.
W. Carlisle, Assistant.
New Zealand. — Lieut.-Col. G-. L. Tupman, R.M.A., Chief.
Lieut, Coke, R.N.
Brisbane. — Capt. Morris, R.E., Chief.
Capt. Darwin, R.E. (who returned via Singapore, and connected the
station at Port Darwin with Singapore for the determination of
the differences of longitude between Greenwich and the Australian
stations).
C. E. Peek, F.R.G.S. (who provided his own instruments).
An assistant selected from the corps of the Royal Marine Artillery was attached to
each of these expeditions, with the exception of that to Madagascar.
Longitude Determinations in connexion with the Work.
To carry out the work undertaken in a satisfactory manner, it was desirable to
obtain a telegraphic determination of the differences in longitude between the
Australian stations, the New Zealand stations, and Greenwich. Such determinations
had long been a desideratum in science, but difficulties had been experienced in
obtaining a skilled observer and instruments for the determination of the difference
in longitude between Singapore and an Australian station, which was required to
complete the chain of determinations which had already been made. It was therefore
arranged that Capt. L. Darwin, R.E., one of the observers attached to the expedition
to Brisbane, should return by Singapore and make the necessary observations there,
and interchange signals with an Australian observer at Port Darwin. This work was
carried out ; and the completion of the determination of the differences in longitude
between the Australian stations and Greenwich is one of the most valuable indirect
results which have been obtained through these expeditions.
The longitude of the station, Nos Vey, in Madagascar, was determined by
Capt. Aldrich, R.N., H.M.S. " Fawn," from chronometer runs between the Royal
Observatory, Cape of Good Hope, Natal, and Madagascar.
A large number of chronometers, independent of those usually carried by Her
Majesty's surveying ships, were added to the equipment of the expedition to
Madagascar for this purpose.
The longitude of Bermuda was determined by chronometer runs between
Bermuda and New York. The work was carried out by Lieut. Neate, R.N., the
errors of the chronometer at New York being supplied from the Observatory at
Washington, whose difference of longitude from Greenwich had already been tele-
graphically determined ; the errors of the chronometers at Bermuda were determined
by the observers of the expedition.
The Committee have to express their thanks to the Superintendent of the Washing-
ton Naval Observatory and the Directors of the Telegraph Lines from Washington
3
to New York, for the assistance rendered in the determination of the longitude of
Bermuda.
The longitudes of the stations selected by Capt. Wharton, " Straight Arm Station "
and "Sandy Hill," Straits of Magellan, were connected by him with the station
occupied by the German expedition at Punta Arenas (Sandy Point) whose longitude
has been determined by Prof. Auwers, and the result communicated to the Committee.
The longitudes of the other stations had either previously been determined by
telegraphic communication, or were connected by the observers with stations whose
longitude had previously been so determined.
The Committee have to express their great obligations to the Colonial Governments
of Canada, Victoria, New South Wales, South Australia, Queensland, New Zealand,
Mauritius, Natal, and the Cape of Good Hope for the assistance rendered to the
expeditions sent from this country, and for the equipment of Colonial observers who
have taken an important part in the observations. The Committee have also been
greatly indebted to Earl Crawford, Mr. Barclay of Leyton, and Col. Tomline of
Ipswich, for arrangements which rendered it possible for the Committee to secure the
assistance of Dr. Copeland, Mr. Talmage, and Mr. Plummer, who took charge of the
expeditions to Jamaica, Barbados, and Bermuda respectively ; and their thanks are
also due to the various telegraph companies for facilities afforded during the progress
of the work.
The instruments used by Dr. Copeland were also lent to the Committee by Earl
Crawford.
The thanks of the Committee are particularly due to the Directors of the Eastern
Extension Australasia and China Telegraph Company for the use of their wires, to
Mr. Browning, manager of the Singapore office, for assistance rendered to Capt. Darwin
at Singapore, and to the Batavian Government and Capt. Helb for assistance rendered
at Banjoewangy in the determination of the Australian longitudes.
The Committee had the benefit of the services of Mr, Robert W. F. Harrison as
Secretary up to 1882, April 30, and from that date of Mr. P. Edward Dove, who,
since 1884, April 1, has acted as Honorary Secretary, without remuneration.
At the request of the Committee, Mr. E. J. Stone has undertaken the duties of
Directing Astronomer in connexion with the arrangements for the observations of the
Transit of Venus, and with the subsequent deduction of the results. Mr. Stone's
report is herewith appended.
G. G. STOKES, Chairman.
J. C< ADAMS.
W. H. M. CHRISTIE.
J. R. HIND.
GEO. HENRY RICHARDS.
E. J. STONE.
P. EDWARD DOVE, Honorary Secretary.
A 2
Report of the Directing Astronomer on the reduction of the observations of the
Transit of Venus 1882, December 6, with the results deduced therefrom.
Calculations.
The Right Ascensions, North Polar Distances, and Radii Vectores of the Sun and
Venus have been interpolated from the Nautical Almanac.
The value of the solar parallax adopted in the calculations has been w = 8""85.
The angular semi-diameter of the Sun at the mean distance of the Earth has been
assumed to be equal to 960" ; and the semi-diameter of Venus at the mean distance
of the Sun from the Earth to be equal to 8"*472 ; and with these data the residual
errors have been formed.
os is the relative correction in seconds of arc required by the semi-diameter of the
Sun and Venus computed with these data, and Sa, 8A, are the corrections which the
tabular Right Ascensions and the North Polar Distances require in seconds of time and
arc respectively.
Col. Clarke's constants for the figure of the Earth have been adopted in the
calculations.
The greater part of the arithmetical computations have been made by Mr. H. J.
Carpenter, to whom my thanks are due for the accuracy with which the work has
been done.
Contact Observations.
The observations of contact have been arranged to afford two independent deter-
minations of the Sun's distance from a comparison between the contacts made at two
classes of stations —
* f Contact at ingress accelerated by parallax.
1 Contact at ingress retarded by parallax.
-o J Contact at egress accelerated by parallax.
\ Contact at egress retarded by parallax.
Ingress Observations.
Of the observable contacts in a Transit of Venus those near the internal contacts
at ingress were expected to yield the most satisfactory results. The times recorded
at the external contacts are merely the times when the observer first saw the plane>t
Venus projected on the Sun's disc. The recorded times, therefore, greatly depend
upon the fact whether the observer's attention was or was not directed to the part of
the Sun's limb at which the contact first took place. The times recorded are all late ;
and the estimations which some of the observers have given of the degree of lateness
are not such that accurate calculations could be based upon them. It was not
expected that any accurate value of the Sun's distance would be obtained from the
discussion of the times recorded for the external contact at ingress. But these
observations have been discussed chiefly with a view of testing the extent to which,
considering the somewhat discordant material available from the observations of the
external contact at ingress, we may trust to the assumption that the recorded times
refer to a phase which takes place with the same angular separation of the centres at
all the stations. The result is so far satisfactory that the value of the parallax thus
deduced agrees well within its probable error with the most reliable results which can
otherwise be obtained. The result thus obtained from the external contacts at
ingress is —
7T = 8"-760 ± 0"-122.
With respect to the internal contacts there are at least four contacts of a more or
less distinctive character which have been seen and described within a minute of time
over which some connexion between the limbs, due to atmospheric disturbance or
otherwise, appears under certain conditions and with an unclouded sky to extend : and
any one of these phases may have been called " contact " by an observer.
These different kinds of contacts may be described as follows : —
(1.) Contacts between the Sun's limb and the limb of Venus as distinguished from
contacts with the atmosphere of Venus. These contacts are sometimes spoken of
as " geometrical contacts " and sometimes as " tangential contacts." The times at
which such contacts took place are not usually recorded by the observers.
(2.) Contacts between the Sun's limb and the atmosphere of Venus, or " First flash
of Sun's light through the atmosphere of Venus." Several observers have
A 3
recorded the times at which such contacts took place, and these contacts have
sometimes been called by observers " geometrical contacts."
(3.) The last appearance of any well-marked and continuous disturbance of the
illumination of the Sun's limb as distinguished from atmospheric tremor, or the
time of some marked and striking change in the colour or character of the
connexion between the atmosphere of Venus and the Sun's limbs.
(4.) The last appearance of a disturbance of the illumination of the Sun's limb from
any cause whatever, or " disturbance from atmospheric tremor," " detached •
" portions of the atmosphere of Venus jumping backwards and forwards between
" the limbs," "• interference lines disturbance," or "full sunlight now between
" Venus and the limb of the Sun."
These internal contacts appear to correspond to mean separations of the centres of
Venus and the Sun of about —
(1) 942-2
(2) 941-4
(3) 939-8
(4) 938-6.
The observers who have recorded times for the phases (1) and (4) are not sufficient
in number to allow a value of the Solar Parallax to be obtained from their
discussion with any pretensions to accuracy, but 11 observers have recorded times
corresponding to phase (2), and these give a value of the mean Solar Parallax —
8:-874 + 0"-081,
a value which agrees within less than its probable error with the result obtained from
a discussion of the principal phase.
Nearly all the observers who have recorded times for more than one phase of the
internal contacts have described phase (3) as the most distinctive contact of the four ;
and in many cases it is described as the only distinctive contact. It will be assumed,
therefore, that when only one time is recorded as the time of contact, the observer's
recorded time refers to phase (3), unless the observations of contact were interfered
with by cloud, and the observer expressly states that his observations are those of
apparent or geometrical contact, in which case the observations have been treated
as those of apparent contact, or phase (2), and included in the discussion of such
contacts. There are only two such cases amongst the observations included in the
present report, and in both these cases the recorded times are found tt> agree closely
with the other recorded times for the apparent contact. When more than one time
is recorded, the observer's selection of the distinctive phase which he wishes to have
regarded as corresponding to " true contact/' or as phase (3), has been accepted and
used for the discussions.
A discussion of the 24 observations of internal contact at ingress which have been
forwarded to the Committee gives a value —
8"- 823 ±0"- 023
for the value of the mean Solar Parallax. This corresponds to a mean distance of the
Earth from the Sun of 92,654,000 ± 240,000 milps.
Egbess.
The internal contact to which the attention was directed in the instructions to
observers was described as follows : —
hk The time of the first appearance of any well-marked and persistent discontinuity
in the illumination of the apparent limb of the Sun near the point of contact," to
which was added the following explanation : —
" The expression ' well-marked and persistent discontinuity in the illumination of
the apparent limb of the Sun near the point of contact ' is intended to guard observers
against giving times for the contacts when there may be a suspicion only of some
slight disturbance, haze, shadow, or interference phenomena. It is a point of primary
importance that all the observers shall, as far as possible, observe the same kind of
contact ; and it is therefore desirable that the times recorded for contacts should
refer to some marked discontinuity in the illumination of the Sun's limb, about which
there cannot be a doubt, and which may be supposed to be recognizable by all the
observers."
Many of the observers at egress have only recorded one time near the internal
contact as the time of internal contact, but others have recorded two or three times,
which are variously stated to correspond to —
(1) suspicion of haze or atmospheric tremor,
(2) haze or shadow,
(3) limbs of Sun obscured or geometrical contact.
The times corresponding to suspicion of haze or atmospheric tremor should not, in
strict accordance with the instructions, have been recorded, and cannot, therefore, be
combined with other times recorded for distinctive contact. It is possible, therefore,
to consider the observations of contact when only one time is recorded as corresponding
to either —
(2) haze or shadow,
(3) limbs obscured or geometrical contact.
The first assumption should be true if the instructions have been strictly carried out
in all cases and the sky had at all stations been sufficiently clear for observation of the
haze or shadow phenomena.
The second would assume that the observers who have only given a single time
have not seen or have disregarded the haze or shadow contact, and have waited until
the Sun's limb became obscured by shadow or haze as dark as the outer limb of the
planet or the contact had become a geometrical contact.
The difference between the results thus obtained, although not inconsiderable, is
well within their probable errors.
The first solution leads to a value —
7T = 8""827 ± 0"-050 ;
the second would give the larger value —
it = 8"-882 ± 0"-043.
The probable errors of these two results are so nearly equal that it has been thought
desirable to give a third solution on the assumption that the mean of the times
recorded for the different kind of contacts by some of the observers would on the
average best agree with the kind of contact to which the single time records refer.
The value of the solar parallax thus obtained is —
7T = 8"-855 ± (T-036.
The rather large probable errors of the first and second solutions of the equations,
and the near equality of these probable errors would appear to point to the solution
obtained by taking the mean times 8"*855 as the value which best represents the
egress observations here collected. This value corresponds to a mean distance of the
Earth from the Sun of 92,319,000 ± 370,000 miles.
The external contacts at egress give —
7T = 8"-953 ± 0"-048.
If we adopt the mean of the results for ingress and egress, the effects of any small
error 3a will be sensibly eliminated, and we should thus obtain from the internal
contacts —
* = 8"'839 ± 0"-021 - 0"-0015 3a - 0"'0063 3A,
or 7T = 8"-825 ± 0"-028 - 0"-0015 3a - (T0063 SA,
according as we take the second solution or the first solution for the egress result.
Those results agree so closely that the value —
8"-832 ± 0' / -024 - 0"'0015 3a - 0"'0063 3A
may be accepted as that which represents the internal contacts. This value corresponds
to a mean distance of the Earth from the Sun of 92,560,000 ± 250,000 miles.
Details of Observations.
The following are the details of the observations given by the different observers.
It has not been thought necessary to give the drawings in this Eeport.
A 4
MAURITIUS.
h. m. s.
Longitude of station - 3 50 12*0 E. of Greenwich.
Latitude „ - - 20 5 39 S.
Observations of the Contacts of the Sun and Venus.
Dr. C. Meldrum.
Observed with a 6-inch equatoreal by Cooke and Sons ; power 150, with a first
surface reflecting prism, and a neutral tint glass wedge. Times noted by chronometer
Kullberg No. 3400.
Ingress.
The weather was unfavourable, but less so than had been expected. For several
weeks previously there was scarcely a day on which the Transit could have been seen.
In the forenoon of the 6th clouds began to gather, and as the time of the first external
contact approached fully, seven-tenths of the sky were covered with cumuli, nimbi, and
cirro-strati.
All preparations and arrangements having been made, I took up my post at the
equatoreal four minutes before the expected time of the first contact ; Mr. A. N. Figou,
the Second Assistant, recorded the times.
Until 5h. 40m. 18s. L.M.T. by the chronometer, the Sun was obscured. He then
shone out through cirro-strati.
5h. 41m. 24s. by chronometer. At this instant I thought something like smoke or a
shadow had just impinged upon the Sun's limb near the point where the external
contact was expected, and I called out " contact," but it was not until seven or eight
seconds later that I was sure it was Venus. There was a good deal of boiling at the
time.
From 5h. 41m. 24s. to 5h. 59m. 46s. clouds were passing off and on, and the Sun
did not at any time shine in a completely clear sky. The planet when seen was
intensely black, and apparently quite round, notwithstanding that there was always
more or less boiling, and at times, much. Owing perhaps to the clouds and to my
attention being mainly directed to the cusps and the dark space between them. I did
not see, up to 5h. 59m. 46s., any part of the planet's limb illumined, but the place
occupied by the portion of Venus outside the Sun appeared lighter than the rest of
the background. Except when clouds were passing, the cusps were very distinct.
At 5h. 59m. 46s. the Sun became completely obscured, and did not re-appear, and then
only dimly, until 6h. 0m. 26s. From the glimpses obtained during the next ten
seconds, it appeared that internal contact had not taken place.
The weather now cleared up a little, and at 6h. 0m. 42*5s. by chronometer, the limbs
of the Sun and planet seemed to be connected by a haze or ligament, which blunted
the cusps. On each side of what was about apparently to become the point of
contact, the planet's limb was to some extent illumined. The haze and the aureola
were diminishing. The planet did not appear to be inside the Sun's disc. It seemed
that what was about to occur would be " pure geometrical contact."
6h. lm. 3s. by chronometer. For an instant light seemed to flash in between the
limbs and to connect the cusps, but instantly after a brown drop or button seemed to
connect the limbs at the point of contact. This drop, however, lasted only about
two seconds. In another second or two a fine thread of light separated the Sun and
planet. The time given (6h. lm. 3s.) is the instant of the last appearance of
discontinuity in the illumination of the Sun's limb near the point of contact.
From 6h. lm. 3s. to 6h. lm. 27'5s. filmy clouds were passing, but, at the latter time,
a distinct band of light separated the limbs.
Owing to an accident no photographs were taken. Preparations had been made for
taking a number of pictures, but the first assistant (Mr. Bell) was blinded, and his
mouth and tongue scalded by the contents of a bottle of ammonia, which he was
opening, flying up into his face, between 1 and 2 o'clockNsn the 6th, and disabling him
for nine days. Extra assistants were at hand to take photographs, but it was found
that the baths had been spoiled by the ammonia.
Collecting the times, we have —
h. m. s.
1. First seen - - - - 5 41 24 by chronometer.
2. Connexion by haze or ligament - 6 42*5
3. Last appearance of discontinuity, &c. 6 13 „
We therefore get for times of contacts —
Ingress.
Chronometer Time. Local Sidereal Time. Local Mean Time. (rreenwich Mean Tin
h. m. s. h. m .
1. 5 41 24 22 42
2. 6 42-5 23 1
3. 6 1 3 23 2
*• h. m. s. h. m. s.
19-01 5 41 20-22 1 51 8-22
40-75 6 38-78 2 10 2678
1-29 6 59-28 2 10 47-28
Whence the equations —
*
1. 5-836= -2-160 S^-
2. 1-988 = -2-143 Sv
3. 3-022 = -2-142 oV
_8R _S p +0-522 8a +0-825 8A -0-053 &
_8R +8 P +0-481 8a +0-854 8A -0-051 &
_8R +8p +0-480 8a +0-854 8A -0O51 3<
MADAGASCAR.
Longitude of station
h. m. s.
- 2 54 24-01 B. of Greenwich.
Latitude „
- 23 38 57'6 S.
Observations of the Contacts of the Sun and Venus.
Rev. S. J. Perry.
Observed with a 6-inch Simms' equatoreal; power 150, negative eye-piece with
solar prism and graduated wedge. Times noted by chronometer Carter 380.
Ingress.
Sky cloudless; high south wind. The telescope had been tested for illuminating
and defining power on previous days. It shows exceedingly well the faculse and
mottled appearance all over the solar surface on any ordinary clear day. The fifth
star in the quadrilateral of the nebula in Orion was clearly seen, and the sixth glimpsed
The companion of Rigel was a very easy object to observe, and that of a Arietis was just
visible. With first magnitude stars, a purple halo surrounds the star when in focus •
when the focus is shortened the green centre and rings are surrounded by a purple halo'
and when the focus is lengthened, the purple centre is enclosed within well-defined
greenish rings ; the power used in these observations was 150. The driving clock was
very uncertain m its rate, so every preparation was made to replace it and its slow motion
cord by an ordinary Hooke's joint slow motion rod, if required. A series of measures of
the distance of a well-defined spot from the E. limb of the Sun was made during the
afternoon to test the performance of the double image micrometer, which was found to
work fairly. The time was taken by Mr. W. Carlisle. The part of the wedo-e used
during the transit was determined several times by noting the extreme positions in
which a good definition could be obtained of the f aculae and granulations on the Sun'«
surface and adopting the mean. This adopted mean was found to agree very closelv
with the position given by using the least amount of light which would enable two
spider lines placed 1" apart to be well divided.
The field of the wires of the telescope, power 150, embraced about 30° of tie Sun's
circumference, and, as I placed at the centre of the field, the point of the limb 35° S
of the Sun's B. point, instead'of 35° B. of the Sun's S. point, I did not see Venus till'
a 22653. B
10
she was partially on the Sun. I picked her up as I swept round the limb towards the
south. The wavy motion of the Sun's limb was very considerable, the undulations
being of great length, so it would have been impossible to observe external contact
with even the ordinary accuracy of such an observation.
The wind from the S. was very high and clouds of sand descended upon us during
the transit, but our telescopes were fairly protected by reed erections put up by the
natives, and there was consequently little vibration in the Simms' achromatic. When
Yenus was about half on the Sun, her atmosphere first became visible. The upper
portion of the limb of Venus outside the Sun was clearly seen, the planetary atmos-
phere being of a dull pearly white, much less bright than moonlight. The faculae and
mettled appearance of the Sun in the vicinity of the planet were well marked, and these
served to fix the focus accurately.
At 20h. 35m. 0s. by chronometer, the lower part of the planet's limb outside the
Sun became visible (Fig. 2), and at 20h. 35m. 51* 2s., the whole of Venus was seen
(Fig. 3). The atmosphere of the planet never increased in brilliancy, and I was able
to watch it until it came into apparent geometrical contact with the Sun's limb at
20h. 41m. 37 ' 5s. by chronometer. I lliight easily have observed the apparent contact
of the inner darker portion of the planet with the Sun's limb, as this darker portion
preceded very considerably that of the atmosphere, but I kept my attention fixed on
the planet as a whole including its atmosphere, and neglected entirely the apparent
contact of the inner dark circle. (Fig. 4) gives the apparent geometrical contact of the
planetary atmosphere with the Sun's limb. There was no apparent departure of the
planet from the circular shape, no drawing out of the limb of Venus towards the Sun's
limb, but, after the apparent geometrical contact of the atmosphere of Venus with the
Sun's limb, a dark shade remained behind the advancing planet.
At 20h. 42m. l'6s. by chronometer, this shade diminished slightly in intensity
(Fig. 5 to Fig. 6), and at20h. 42m. 48 '8s., I first suspected a break in the shade behind
the planet.
At 20h. 42m. 59*9s. by chronometer, the well-defined and permanent ligament
certainly ceased to exist. This last and most important phase may be represented by
the change from (Fig. 6 to Fig. 7). The dancing shadow in (Fig. 7) I neglected
altogether as the union between the limbs was no longer established by it. When
Venus was well within the Suns limb, I touched the focussing screw, and I felt con-
vinced at the moment that the planet might have been f ocussed more sharply ; still the
test of clearly seeing the mottled appearance all over the solar surface appeared to be
satisfactory. A light around Venus was still visible on her following limb when she
was entirely on the Sun, but this soon gave way to the slaty appearance of the rest of
the planetary disc, and was probably not due to the atmosphere of Venus.
After Venus had been on the Sun for several minutes, I tried the double image
micrometer for measuring diameters and distances of limbs, but the driving clock of
the equatoreal worked so indifferently, owing possibly to the falling sand, which
penetrated everywhere, that I soon came to the conclusion that no reliable measures
could be taken, and therefore preferred comparing the chronometer at once. During
the transit I was obliged to discard the driving clock and use an ordinary slow motion
rod for the A.R. circle. Throughout the observations the sky was cloudless, but the
high wind and sand interfered a little.
Collecting the times relating to the contacts, we have —
h. m. s.
1. Geometrical contact - - 20 41 37 * 5 by chronometer.
2. Break suspected - - - 20 42 48*8
3. Well-defined and permanent
ligament certainly ceased to
exist - ' - - 20 42 59*9
We therefore get for times of contacts —
Ingress*
Chronometer Time.
Local Sidereal Time.
Local Mean Time.
Greenwich Mean Time,
h. m. s.
1. 20 41 37-5
2. 20 42 48*8
3. 20 42 59-9
h. m. s.
22 5 22-48
22 6 33-97
22 6 45-10
h. m. s.
5 4 20-60
5 5 31-90
5 5 4300
1). m. s.
2 9 56-59
2 11 7*89
2 11 18-99
]]
Whence the equations-
1. -0-782 =
2. +2-837 =
3. +3-402 =
-2-003 &V -SB, -Sp +0-482 8a +0-853 SA -0-051 .8*
- 2-003 Sv -8R +Sp +0-480 8a +0-854 8A -0-051 8*
-2-003 for -8R +8p +0-479 8a +0-855 8A -0-0518*
Observations of the Contacts of the Sun and Venus.
Rev. W. Sidgreaves.
Observed with a 6-inch equatoreal; power 150. Times noted by chronometer
Roskell.
Ingress.
Geometric contact of illuminated atmosphere of Venus at 23h. 31m. 48*2s. by-
chronometer (1).
Last appearance of darkest shade between planet and Sun at 23h. 32m. 13'2s. by
chronometer (2).
Last appearance of any shade between planet and Sun at 23h. 32m. 18s. by
chronometer (3).
The darkest shade mentioned in phenomenon (2) was not dark. It was reduced to a
faint shade caused by the continuance of the bright ring of atmosphere round the
planet. This bright ring remained until the contact was clearly over. My telescope
has been all along extremely sensitive to the wind or the slightest touch. Even a
careless move of the slow motion rods has always made a star or the Sun dance in
the field. The wind was high during the transit ; but, by the kind assistance of
Captain Aldrich (H.M.S. "Fawn"), a large screen had been erected to protect the
instrument against the wind. This succeeded admirably until the critical moment.
A gust of wind caught the instrument just at the time of (2) and (3), and made the
tube oscillate to an amount which made it extremely difficult to watch the delicate
shade of contrast between the bright ring round the planet and the sunlight. The
definition was perfect. I could see the rice grains and faculas extremely well.
Collecting the times, we have —
h.
1.
2.
Geometric contact of illuminated
atmosphere of Venus -
Last appearance of darkest shade
between planet and Sun -
3. Last appearance of any shade
between planet and Sun
Comparison of Roskell with sidereal clock —
23 31 48-2 by chronometer.
23 32 13-2
23 32 18
Date.
Time by Sidereal Clock.
1882 December 6
h. m. s.
21 25 160
22 16 25-0
We therefore get for times of contacts —
Ingress.
Local Sidereal Time. Local Mean Time.
Time by Roskell.
Correction of Eoskell to
Local Mean Time.
+ signifies Slow.
h. m. s.
22 51 0-0
23 42 10
h. m. s.
+5 33 11-94
+5 33 11-88
Chronometer Time.
Greenwich Mean Time.
h. m. s.
1. 23 31 48-2
2. 23 32 13-2
3. 23 12 18-0
Whence the equations —
h. m. s.
22 6 2-07
22 6 27-14
22 6 31-95
h.
5
5
5
m. s.
5 0-09
5 25-09
5 29-89
h. m. s.
2 10 36-08
2 11 1-08
2 11 5-88
1. 1-223 =
2. 2-493 =
3. 2-740 =
2003 3*- - oR - 3p +0-481 3a 4-0-854 8A -0-051 U
2-003 Stt -3R + 3p 4-0-480 S« +0-854 SA -0O51 o*
2-003 3tt - 3R + r>f +0-480 3a +0-854 SA -0-051 ot
22653.
c
12
Observations of the Contacts of the Sun and Venus.
Commander P. Aldrich, R.N.
Observed with a 4-inch equatoreal ; power 175 ; there was no prism attached to the
eye-piece, a neutral tint wedge was placed between it and the eye. The fittings for
this together with a slow motion focussing screw having been made for me under the
direction and on the plan of Mr. Gr. EL Weeks, the Chief Engineer of the " Fawn,"
Times noted by Lieut. B. 0. H. Helby, R.N., by pocket chronometer Dent 19974.
Ingress.
A northerly wind had been blowing for some days prior to the 6th, and clouds
obscured the Sun at 4 p.m. for three or four days before the transit. The morning
of the 6th was very overcast and cloudy, with a little B.S.E. wind, which freshened
after 8 a.m., followed round with the Sun, and rapidly cleared the sky of cloud. In
the afternoon the wind was fresh, force 4*5 from the S.S.W. and S.W., the atmosphere
very clear, and the Sun very bright.
The telescope was somewhat shaky; it was equatoreally mounted on a wooden
tripod stand, but I had had a large tent of oars and canvas pitched over it, without
which I do not think any observation could have been satisfactorily made,
The heat of the Sun was so great that during 20 minutes before the transit a small
speck or two of the colouring matter on the wedge was apparently removed by it.
This, however, only necessitated my moving the wedge about one-eighth of an inch
nearer to the darker end, and did not ultimately interfere with what I had decided
on as the most convenient depth of shade. There being no prism attached to the
eye-piece, the Sun had to be faced, but the glare was to a great extent diminished by
a canvas screen carried across the tent under the telescope.
The definition was fair, though not comparable with those as viewed in the 6-inch
telescopes ; the rice grains were beautifully distinct in the latter, but could not be well
distinguished in the 4-inch.
The watch having been compared, Helby and I were in readiness at 4.30 p.m. M.T.P.,
and at 6h. 21m. Os. by watch I saw a slight indentation or notch in the Sun's limb in
the middle of the field, which I concluded was Venus. I gave the signal, and after
watching for a few seconds to see that I was not mistaken, I called Helby to come
and look at it. I hesitate to estimate how long this was after external contact, but
probably over a minute, and possibly more. From this time I did not observe anything
worth recording till Venus was nearly, if hot quite, half way on the Sun's disc. At
this time, 6h. 33m. T2s., a faint rim of light was seen to extend round the apparent
upper half of Venus off the Sun, and within a very short time, at 6h. 33m. 51*2s., the
ring was complete and the whole extent of Venus visible.
After this I observed nothing worth recording until 6h. 38m. 5s., when a black drop
was apparently forming, and the edge of Venus about the Sun's limb became rather
ill-defined.
The time here given may be considerably in error, but it was that at which I could
first make certain of a wall-like appearance between the cusps.
At 6h. 39m. 42'4s. by chronometer, I considered apparent contact was made. This
alludes to an instant when the edge of the luminous ring round Venus was estimated
to be in contact with the Sun's limb. This phase was rather interfered with by a
dark but very narrow band, which seemed to draw the limb of Venus towards the
Suns limb, with small perpendicular edges. And yet this did not assume what I had
been led to believe was the appearance of the black drop. At this instant, however,
there was no appearance of sunlight between Venus and the Sun's limb, and the " well
" marked and persistent discontinuity in the illumination of the apparent limb of the
" Sun " still continued.
At 6h. 40m. 14s. by chronometer, there was undoubted light between the apparent
limb of the Sun and Venus, and the " well marked and persistent discontinuity " had
ceased. I am inclined to think that I may have been perhaps a few seconds late in
estimating, or rather, observing this, but I was hardly prepared for such a sudden
termination of the observations. At this time, however, there was no doubt whatever
about the internal contact being over.
After this there was a faint flickering narrow band, which extended from Venus to
the Sun's limb, and had I not been particularly cautioned not to pay any attention to
anything, after the sunlight had been seen, I think I should have thought this was the
ligament ; as it was, beyond watching it, I paid no attention to it, and Mr. Helby had
13
a look at it. This continued some little time after Venus was well clear of the Sun's
limb, and no time was taken.
When Venus had got some half a diameter on the Sun I observed a faint luminous
haze over the eastern side of the planet, first in the upper portion and then in the
lower, till at length it became like a dull coloured moon or crescent on the part of the
planet nearest to the Sun's limb.
A sheet of small sketches is forwarded with this, which may assist in showing what
I actually saw.
Collecting the times relating to the contacts, we have —
h. m. s.
1. First seen - - - - 6 21 by chronometer.
2. Estimated apparent contact - - 6 39 42*4 „
3. Light between Venus and Sun - 6 40 14 „
We therefore get for times of contacts —
Chronometer Time.
Ingress
Local Sidereal Time.
Local Mean Time.
Greenwich Mean Tin
h. m. s.
1. 6 21
2. 6 39 42-4
3. 6 40 14
h. m. s.
21 47 19-67
22 6 5-10
22 6 36-79
h. ra. s.
4 46 20-75
5 5 311
5 5 34-71
li. m. s.
1 51 56-74
2 10 39-10
2 11 10-70
Whence the equations —
L 6-989 = - 1-998 8tt - 8R - 3p +0-521 oa +0*825 8A -0-053 U
2. 1-371 = - 2-003 oV - m + o> +0-481 3a +0-854 8A -0051 U
3. 2-977 = - 2-003 oV - 8E + 8p +0-479 §a +0-855 SA -0-051 U
DURBAN.
The observations were taken at the Natal Observatory by Mr. B. Neison.
The longitude of the station determined telegraphically from the Royal Observatory,
Cape of Good Hope, and supplied by Dr. Grill is : —
h. m. s.
2 4 1-18 B. of Greenwich.
The latitude is —
29 50 47-4 S.
Observations of the Contacts of the Sun and Venus.
Mr. B. Neison.
Observed with the 8-inch equatoreal of the Natal Observatory, reduced by means of
a cardboard stop to 6-inches ; power 160 on a Merz polarising eye-piece. Definition
very unsteady. Times noted by chronometer Poole 1407.
Ingress.
External contact lost owing to unsteadiness.
Internal contact observed at 4h. 17m. 59s. by chronometer.
As Venus approached internal contact a thick dark ligament was seen, gradually
narrowing till about 10" wide, then it commenced to lighten, flickered a little, grew
greyish in hue and suddenly broke up, a narrow line of light darting across the grey
shade, and the whole shading vanished in less than five seconds. The time was the
instant when the shading broke up. A second or so more, .and sunlight was distinctly
visible between Venus and the limb. This was at 4h. 18m. 6s. by chronometer. At
this time contact was past. The ring of atmospheric light was yellowish in hue and
was distinctly seen from the time that Venus was half on the Sun, and it did not
disappear till a minute after it was quite on the Sun. Traces of it could be distinctly
seen for some time after.
C 2
14
The time was read out aloud and recorded by Mr. P. Sandford of the Durban High
School.
We therefore get for time of contact —
Ingress.
Chronometer Time. Local Sidereal Time. Local Mean Time. Greenwich Mean Time.
h. m. s. h. m. s. h. m. s. b. m» s.
4 17 59 21 16 3613 4 15 3399 2 11 3281
Whence the equation —
3"225 = -1-903 &V - SR + 8p +0-481 8a +0*854 3A -0-051 U
CAPE OF GOOD HOPE.— ABERDEEN ROAD.
The country round about the station is almost a desert, " The Karroo," and the
definition of the Sun in the middle of the day or afternoon was never good. By
7 a.m. everything at a short distance could be seen quivering to an extent never before
witnessed.
The longitude of the station determined telegraphically from the Royal Observatory,
Cape of Good Hope, and supplied by Dr. Gill, is —
h. m. s.
1 37 15-62 E. of Greenwich.
The latitude, also supplied by Dr. Gill, is —
32 45 56-5 S.
Observations of the Contacts of the Sun and Venus.
Mr. W. H. Finlay.
Observed with a 6-inch equatoreal, positive eye-piece, power about 180. The
brightness of the field was carefully regulated in accordance with the instructions of
the Committee. Times noted by chronometer, Molyneux, 2184.
Ingress.
. The Sun's limb was boiling excessively up to about a minute before the time of
external contact. It then became much steadier, and contact was noted at 3h. 28m. 55s.
by chronometer. The notch was very small when first seen, and was exactly at the
point where I was looking.
When Venus was half way on to the Sun's disc that part of the planet still outside
was visible as a darker body on a lighter background, with a very faint rim of light at
the outer preceding edge. This light got brighter and gradually crept round the edge
till at 3h. 42m. it extended completely round.
At 3h. 47m. 45s. the dark body of Venus and the Sun's limb produced would have
been tangential, but the ring of light still extended outside.
The cusps of the Sun came gradually closer, till at 3h. 48m. 16s. by chronometer,
the dark body of Venus was quite inside the Sun, while the bright ring just extended
to the Sun's limb, and a light brown shade was visible all across the space between.
This shading was always very light, and did not change colour, so far as I could see.
It gradually got fainter and narrower in the direction perpendicular to the line of
centres. The Sun's limb was now boiling, but at 3h. 48m. 57s. by chronometer, there
seemed to come a roll of sunlight, which swept the haze right away, and, after this,
though some slight disturbances, two or three little streaks of haze jumping from one
limb to the other were seen for a few seconds ; there was no more continuous
connexion.
15
When Venus was well on the Sun there seemed to be a portion of the disc round
the outside and of a breadth equal to about one-eighth of the diameter, when the
planet was not so dark as over the rest, but this was a totally different thing in size
and appearance to the bright rim seen before.
Collecting the times relating to the contacts, we have —
1. First contact -
2. Tangential contact
3. Last permanent connexion
We therefore get for times of contacts-
h.
3 28 55 by chronometer,
3 47 45
3 48 57
Chronometer Time.
Ingress.
Local Sidoral Time. Local Mean Time.
Greenwich Mean Time.
h. m. s. h. in. s.
1. 3 28 55 20 29 53-89
2. 3 47 45 20 48 4705
3. 3 48 57 20 49 59-25
Whence the equations —
h. m. s.
3 28 55-02
3 47 45-09
3 48 57-09
h.
1
2
2
m. s.
51 39-40
10 29-47
11 41-47
1. 4-086 =
2.— 0-689 =
3. 2-999 =
■1-774 aV -m
•1-824 St -8R
• 1-827 St -SR
-Sp +0-525 &*
+5p +0-484 8a
+8p +0-482 U
+0-822 8A
+0-851 8A
+0-853 3 A
-0-054 U
-0-051 U
-0-051 U
Observations of the Contacts of the Sun and Venus.
Mr. R. T. Pett.
Observed with a 6-inch equatoreal, positive eye-piece ; power about 180. Times
noted by chronometer Molyneux 2275.
Ingress.
First external contact at 20h. 25m. 0s. by chronometer.
Sun's limb boiling terribly for some little time before contact, but quieted down
about a minute before times noted. Venus appeared just where I was looking.
First internal contact at 20h. 45m. 12s. by chronometer. The cusps seemed to
unite suddenly. Bad definition at this time. No black drop or ligament seen.
At 20h. 45m. 30s. the band of light was of sensible width.
I do not think that I was more than two or three seconds out in either observation.
Collecting the times relating to the contacts we have : —
1. First external contact
2. First internal contact
We therefore get for times of contacts —
h.
20 25 by chronometer.
20 45 12
Chronometer Time.
Ingress.
Local Sidereal Time. L^ocal Mean Time.
h. m. s.
1. 20 25
2. 20 45 12
li. m. s.
20 29 50-95
20 50 3-29
h. m. s.
3 28 52-09
3 49 1-12
Greenwich Mean Time.
h.
m.
s.
1
51
36-21
2
11
45-24
Whence the equations —
1. 3-929 = -1-774 for - SR - S> + 0-525 3a + 0-822 3 A -0-054 U
2. 3-201 = -1-827 &V - 8R + o> + 0-481 8a + 0-853 SA -0-051 U
C 3
16
CAPE OF GOOD HOPE.— MONTAGU ROAD.
h. m. s.
jongitude of station - 1 20 8*64 E. of Greenwich.
/ //
Latitude „ - - 33 20 23 S.
Observations of the Contacts of the Sun and Venus.
Mr. A. Marth.
Observed with a 6-inch Grubb equatoreal, a positive Steinheil eye-piece ; power 180.
Times noted by chronometer Birchall No. 308.
Ingress.
After a clear night which had allowed the occultation of Spica to be well observed,
the morning of December 6 was cloudless and calm. Some strong gusts of wind,
about 9 o'clock, however, indicated that the breeze which at Montagu Road springs up
pretty regularly every forenoon, had come earlier and in greater strength than usual,
and it soon became apparent that the day might be one of dust storms, of which we
had already had sufficient unpleasant experiences during the last weeks, without yet
having encountered any of those heavier ones of the occurrence of which we had been
told. The day before a large tarpaulin, kindly lent by the railway officials, had been
erected on poles on the south side of the hut containing the Grubb telescope in order
to screen it from the dust and wind which of late had blown chiefly from the south-
east. But on the day of the transit, the gusts of wind came from several directions,
chiefly from the northern quarter, and fresh precautions had to be taken to shelter the
instrument and to guard it from being too much shaken on its weak stand. The
tarpaulin which serves as a covering of the hut was kept tied down on the eastern and
northern side, and only the south-western portion was lifted up and so fastened to poles
as to allow a free view of the Sun at the time of the transit. In doing this, sufficient
allowance had not been made for the examinations preceding the ingress, but, by the
exertions of Corporal Thornton, the alterations were effected in time, and his makeshift
screening rendered observations with the Grubb telescope possible. The telescope is
too heavy for its mounting, and consequently unsteady, even in the absence of wind.
On the day of the transit, though screened from the force of the wind, it was very
unsteady. To be prepared for the observation of the external contact, I had divided
the circumference of the draw tube into 10 parts, so that each represented 36°, and it
would be feasible to find the point of the Sun's limb, near which contact was to take
place (in position-angle 145°) by first placing a web in the eye-piece in the direction of
a parallel, and then shifting the draw tube 36° in the required direction, so that the
web should become a tangent to the Sun's limb near the point in question. In conse-
quence of the unsteadiness of the telescope, and of the excessive trembling of the sun-
spot, by means of which I attempted to find the parallel, I had to be content with a
rough determination, sufficient however, for the intended purpose (while I was thus
engaged the air outside was so thick with the flying dust that Corporal Thornton after-
wards stated that he had scarcely been able to recognize the outlines of the other huts
at a distance of only nine steps).
At 3h. 11m. 58s. by chronometer, I remarked the first indentation of the Sun's limb
made by the planet, but on account of the trembling I could not estimate by the rate
of its increase how much too late I may have seen it.
At 3h. 17m. 10s. by chronometer, I saw the illuminated atmosphere of Venus outside
the Sun along an arc of perhaps 50° of the planet's periphery. The centre of the arc
was distant from the point opposite to the Sun perhaps 40° towards the south ( or in
position-angle 184°, if the position-angle of Venus at the centre of the Sun was 144°).
At 3h. 22m. the illuminated arc extends now nearly to the point opposite to the
Sun.
At 3h. 23m. 10s., chronometer time, the whole rim of Venus outside the Sun appears
illuminated. The image is becoming extremely disturbed. Violent commotions of
image with occasional moments of better definition. In consequence, when looking for
the geometrical contact, I could not satisfy myself what to consider as the Sun's
circular outline.
17
At 3h. 31m. 6s. I became doubtful whether the refracted light in the atmosphere of
Venus did not apparently broaden or extend outwards by some faint light.
At 3h. 31m. 38s. by chronometer, "last disturbance due to Venus" (expression
jotted down to be understood as the " last appearance of persistent discontinuity in the
illumination of the apparent limb of the Sun ").
As soon as I had assured myself that my counting of the chronometer beats had
been correct I tried to form an estimate of the degree of uncertainty of the time set
down. The phenomenon actually observed had been simpler than the doubt of half a
minute before had led me to anticipate. The direct sunlight had crept from both sides
along the dull refracted light on the rim of Venus ; up to the beat noted there had
been;' persistent discontinuity of the light of the Sun s limb," and immediately after
the tiny thread of light between the cusps was established and was not further disturbed
by the planet. If it had not been for a comparative lull in the trembling at the
critical time, I should probably have been in great uncertainty. As it was,°I felt no
uncertainty that the phenomenon observed had occurred at the beat 38, and that, so
far as I could judge, it was the phenomenon for which I had been watching. Shortly
before the state of the images had threatened to render a trustworthy observation
almost hopeless ; it gave me therefore the greater satisfaction to be able to write down.,
fcC In spite of the trembling limbs I consider the observation fairly good," and I could
not have noted the time of last disturbance four seconds earlier or later, or even
two seconds.
During the ingress Venus had the appearance not of a disc, but of a globe, say, of
pitch m continual ebullition. The outline of the planet was, on the whole, less dis-
turbed than the Sun's limb. I could not discern the granulations of the Sun's surface
with distinctness on account of the trembling. Later on, they became occasionally visible,
and Venus appeared as a deep blue or purple disc with a black centre, the blackness of
which extended on one side nearly to the rim, while on the opposite side the breadth
of the purple was about one-half of the radius of the disc. The planet appeared
surrounded or partly surrounded by a ring or halo of yellowish light, which, where it
appeared broadest, faded away at a distance of perhaps a third of the radius from the
rim. The broadest part of the yellow was near the broadest part of the purple.
Collecting the times relating to the contacts, we have —
li. m. s.
1. First seen - - - - 3 11 58 by chronometer.
2. Refracted light in the atmosphere of
Venus extends outwards by some
faint light - - - - 3 31 6
3. Last appearance of persistent dis-
continuity, &c. - - - 3 31 38
We therefore get for times of contacts —
Ingress.
Chronometer Time.
Local Sidereal Time.
Local Mean Time.
Greenwich Mean Tin
h. m. s.
1. 3 11 58
2. 3 31 6
3. 3 31 38
h. m. s.
20 13 26-49
20 32 37-63
20 33 9-72
h. IB. s.
3 12 27-50
3 31 35-50
3 32 7-50
h. m. s.
1 52 18-86
2 11 26-86
2 11 58-86
Whence the equations —
1. 5-404= - 1-683 8tt -SR -8p +0-524 Sa +0-823 3 A -0-054 8*
2. 1-519= - 1-743 Stt -8R +8p +0-483 8a +0-852 SA -0-051 &
3. 3-159 = - 1-745 Stt -8R +3p +0-481 3a +0-853 8A -0-051 k
Observations of the Contacts of the Sun and Venus.
Mr. C. M. Stevens.
Observed with a 4^-inch equatoreal by Dallnieyer ; a Herschelian prism and a
neutral tint wedge were used. A negative eye-piece, power 145, was employed in
noting first external contact; for internal contact a power of 185 was used. Times
taken by chronometer Arnold 227.
4
18
Ingress.
The early morning was quite clear and calm, but at 21h. the first gust of wind came
from the north-west, raising a large apaount of dust. The direction was rather
unusual, as the daily wind blows from an azimuth point directly opposite, viz., south-
east. The wind continued in the same direction with increasing force, till at midday
it was blowing with a horizontal velocity of from 12 to 15 miles per hour, carrying
with it dense clouds of very fine dust raised from the surface of the ground
surrounding the Observatory, a space of 8 or 10 acres in extent, and almost entirely
bare of shrubs and grass. At times the buildings in the camp a short distance off
were almost completely obscured. I have noted that the winds here, whether they
blow from the N.W. or S.E., usually rise about 9 a.m., and continue through midday
and afternoon until evening, when they subside and leave the nights almost invariably
calm.
I employed the same means as Mr. Marth for getting external contact.
As the time approached of first (external) contact the roof of the hut was opened,
one section only being removed, and the instrument brought to bear upon the Sun,
my seat being placed in a very convenient position for observing. A calico screen
was nailed up to protect my head from the rays of the Sun, the temperature at the
time being considerably over 100° F. in the shade. A canvas screen was also nailed
up to protect the chronometer, as well as the back of my assistant, Mr. J. B. Willis,
of the Telegraph Department, whose services I had enlisted in order that the chrono-
meter times might be properly checked. The screen was not quite effectual, as the
chronometer was for a time exposed to the rays of the Sun. This could not then be
remedied, as I could not permit the chronometer to be moved, as it had been specially
placed for my convenience, and there was no time to arrange any other protection.
Commencement of Transit.
(All the times given are by Arnold 227).
19h. 42m. 6s. First encroachment of planet detected. Must have been on half a
minute or more. As the device failed for determining the position angle of first
contact I guided the telescope by hand along the edge of the Sun, and carefully
watched for the first notching into the Sun's limb.
19h. 48m. 20s. Slight rounding off of planet's limbs at points of junction with the
Sun.
19h. 50m. 10s. First no Led diiierenco of colour in disc of planet and irregularity of
distribution, " chiefly on north side/'
19h. 52m. 56s. When I first saw the whole disc, including the part off the Sun, and
a silvery light along the southern edge, starting from the Sun's limb. Slight rounding
of the cusps.
19h. 54m. 50s. Silvery light now all round the following limb of the planet. Colour
of part of Venus off the Sun, dark olivaceous green shot with a tinge of yellow.
19h. 57m. 50s. Light sharp all round following limb of planet.
Shortly after this time I gave the signal to Willis to attend carefully.
20h. 0m. 0s. Geometric contact. At this time the limbs of Venus and the Sun
were in mathematical contact. Wind lulling ; vibration slight in the instrument.
Suns limb tremulous ; definition variable. This observation is nevertheless good.
20h. 0m. 40s. First glimmer (or thin streak) of light between Venus and Sun's
limb. No black drop seen. Appearance of light instantaneous or nearly so, what
I suppose Johnson saw at Waimea. I take this to be the time of true contact in
accordance with the instructions, or say between 0m. 40s. and 0m. 45s.
20h. 0m. 45s. Glimmer of light between limbs decided. I consider the time of
true contact to have been at the time when I first noted the intervention of the light
between the limbs of the Sun and Venus at 20h. 0m. 40s., i.e., the time of last
appearance of any well-marked discontinuity in the illumination, &c. Persistent
discontinuity was well marked at 20h. 0m. 45s.
Shortly before the time given as true contact, or at about 20h. 0m. 30s., I noticed
an exceedingly narrow black line or filament tangential to the limb of Venus, and
connecting the planet with the Sun. To this I would have given the name apparent
contact, but that I did not note the exact time. This was the only appearance of a
ligament that I saw. It was very much longer than it was broad, being only a very
small fraction of a second of arc by estimate, and very soon gave place to the first
glimmer of light at the time recorded.
19
I saw no Chinaman's cap, as in the artificial transit. 20h. 1m. 12s. " Fully on disc,"
implying the time when the thread of light became so firmly established — the " well-
marked and persistent discontinuity" so far past — that I did not deem it necessary to
record any further times.
This completed my observations at the critical period of internal contact. I am
satisfied with them, not having been distressed by nervous excitement, fatigue of body,
or special fatigue of the eye consequent on long gazing. The use of the medium
portion of the wedge prevented the slightest distress to my eye during the whole
period of observation.
The times noted by Mr. Willis and myself agreed, so that no error of a minute or
half -minute can have crept in.
After first contact I used a power of 185, as I deemed the conditions sufficient to
warrant the higher power. The definition much improved subsequent to the internal
contact, after the planet had been about an hour on the Sun. I could see the " rice-
grain " granulations then, but had not noticed them before, as I had been too absorbed
in observing other phenomena. The driving clock of the instrument worked
satisfactorily.
Fig. VI. (coloured drawings) represents the excentric position of the dark oval spot
on the planet's disc, together with the irregular width of the purplish light extending
inwards from edges of discs. These differences in colour marking became more deeply
marked by using the extreme dark end of the wedge. This drawing was made about
20|h. by Arnold.
Fig. VII., drawn from Fig. VI. on original sheet, represents the time when I first
noticed a yellowish coloured illumination all round the disc of Venus. This coincided
in direct relationship of breadth and intensity with the purple colour on the disc
itself. This encircling colour was a light canary yellow or " ecru " at the limits of the
band, while the portion immediately adjacent to the planet's limb at the broadest
part was of a dusky tinge, between smoky yellow and orange. The direct connexion
as to breadth, position, and intensity of this halo of light with the colour on the
planet's disc was very remarkable.
As a physical question it may have some interest, as possibly bearing on the subject
of the phenomena attending the internal contacts at ingress and egrees. Judging
from the position this halo would occupy in Drawing III., IV., V. (inferred from the
purple band), I beg to venture the opinion that the position angle on the planet of
internal contact at ingress was at a point remote from the zone of greatest density.
And this leads me to remark that in reviewing the circumstances and phenomena
attending the transit, particularly at the critical period of internal contact, I was
surprised at their comparative simplicity. The absence of complex features such as
would tend to create difficulty or uncertainty in noting the times being appreciable.
Had the position angle of internal contact been at the densest portion of the halo
observed, I venture to think that the phenomena would have been much more
complicated.
During the earlier stages of ingress I noticed the rounding of the cusps, but at the
time of internal contact it was not noticed at all. I do not say it was absent, only I
did not look for or observe it. The text of the instructions as to noting " the last
appearance, &c." was constantly present to my mind, and this undoubted bias may
have prevented my noticing one of the phenomena contributing thereto. If the
rounding were present, it certainly was not so remarkable as to obtrude itself on my
notice.
If the broadest portions of the halo may be considered as indicating approximately
the position of line of the equator of Venus, the position angle was remote therefrom.
The planet appeared circular to my mind, and no trace of a satellite could be seen,
although carefully looked for.
At a later stage I used a power of 300, which revealed nothing that had not been
noted before.
The temperature was 102° F. in transit hut at 21h. 8m. (sidereal), and 104° F. at
21h. 18m. (sidereal) in Grubb hut. I did not register the temperature in the
Dallmeyer hut. Barometer reading 27*14 ins. corrected.
In conclusion I would beg to record the services rendered by Mr. J. B. Willis of
the Telegraph Department here, whose training and assistance in the longitude signal
work, added to his natural intelligence, warranted me in enlisting his services as a
check on my chronometer times. I had on the previous day rehearsed the circum-
stances and conditions of the transit with him in the Dallmeyer hut. He performed
his work quite satisfactorily.
a 22653. D
20
Collecting the times relating to contacts, we have
1. First seen ...
2. Geometric (tangential) contact;
limbs in contact
3. First glimmer of light between
Venus and the Sun
4. "Fully on disc" discontinuity so
far past that it was unnecessary
to record any further times
We therefore get for times of contacts : —
h.
19
m.
42
6 by chronometer.
20
20
40
21 1 12
Ingress.
Chronometer Time. Local Sidereal Time. Local Mean Time.
Greenwich Mean Time.
h. m. s.
h. m.
s. h. m. s. h. m. s.
1.
19 42 6
20 14
1-16 3 13 208 1 52 5344
2.
20
20 31
56-86 3 30 54-84 2 10 4620
3.
20 40
20 32
36-93 3 31 34-80 2 11 2616
4.
20 1 12
20 33
8-96 3 32 6-75 2 11 5811
Tit
mce the equations —
1. 7-263 =
-1-683 3tt -
_ 8R - fy +0-523 8a +0-824 8A -0-054 U
2. -0-560 =
-1-741 8*- -
- SB + Sp +0-484 Sa +0-851 8A -0-051 U
3. 1-477 =
-1-743 Sr ■
_ 8R + fy, +0-483 8« +0-852 8A -0-051 U
[4. 3-118 =
-1-741 8tt •
- dR + 3p +0-483 8a +0-852 8A -0-051 U]
Noted by observer " All over " before the time to which the residual 4 corresponds.
CAPE OF GOOD HOPE.— ROYAL OBSERVATORY.
Longitude
Latitude
h. m. s.
1 13 54-74 E. of Greenwich.
33 56 35 S.
Observations of the Contacts of the Sun and Venus.
Dr. D. Gill.
Observed with a 6-inch Grubb equatoreal ; a first surface reflecting prism ; power 110.
Times noted by Mr. Gamble, hydraulic engineer of the Colony, who kindly volunteered
his services, with sidereal chronometer Dent 1581, and by Mr. Fry, Meteorological
Secretary, with mean time chronometer Molyneux 3299.
The object-glass of the instrument is of excellent quality, as proved by its sharp and
easy separation of the double stars X 2055 (1"*7) and X 2799 (1"'4) and by the sharp
manner in which details on the lunar and planetary surfaces are shown.
Unfortunately only four eye-pieces, adapted to the two first surface prisms and dark
wedges were supplied by the Committee. These eye-pieces magnified approximately
110, 180, 300 and 400 diameters. It was impossible, therefore, with so limited a supply
to follow the instructions of the Committee and employ a power of at least 150
diameters, as the eye-pieces were for the Merz equatoreal as well as the Grubb, unless
the air was sufficiently steady to permit the use of a power as high as 300 diameters.
Nor was any positive achromatic eye-piece provided, as was done for the stations at
Aberdeen Road and Montagu Road. Dr. Gill accordingly gave Mr. Maclear the
180 power, and reserved to himself the choice of powers 110 and 300.
Unfortunately the atmospheric conditions would not permit the use of a power
higher than 180, and, even with this power, the images were " waving " and unsatis-
factory. Up till the time that the disc of Venus was bisected by the Sun's limb,
21
attempts were made from time to time to focus with the power of 300, but in vain,
only a violently agitated outline could be distinguished, and it was evident that any
attempt to observe with such a power, under the circumstances, could only end in
complete failure, Dr. Gill therefore adopted power 110, and focussed as sharply as
possible on the Suns limb. In moments of quiet definition some faculse could be made
out, but the rice grains, or mottled appearance of the Sun's disc easily seen with this
power (110) on November 15, could not be distinguished.
Ingress.
I mad e no attempt to estimate accurately the time of external contact. There was
no provision for measuring position angles, and therefore no means of setting on the
*>xact point where contact should be expected.
20h. 9m. 47s. by Dent 1581, or lh. 9m. 5s. by Molyneux, I first saw Venus on the
Sun's limb, but obviously some seconds after true contact.
Signal 2. Ligament changing colour.
„ 3. Disappearance of any continuous ligament or connexion.
The definition very unsteady. Waves of atmospheric undulation passing round
limb. Obliged to use lowest power (110). Shade wedge was set to mean point, that
is the middle point between shade decidedly too dark and decidedly too light for
distinct vision.
In the evening after all observations were over, I was very tired, and entered only
the following additional memoranda in my note book.
Signal 1 was given when I thought I saw a change of colour. I saw immediately
it was an effect of the atmosphere. See Fig. 1.
Signals 2 and 3 represent as nearly as I could judge the instants of the two phases
described by Mr. Stone, i.e.,
b. brighter than planet.
b. ceases to be continuously darker than the cusps a and c.
These remarks refer to Mr. Stones last definition of the phases to be observed as
afterwards quoted in this Report, p. 12. Mr. Stone, however, denotes the cusps by
a and b, and the point of contact by c.
In the first hurried note I was anxious to make it quite clear that my first signal
was not intended to record any phase of contact. Therefore I marked it as a " warning
signal " to prevent possible after mistake, and I made the after note to remind me of
the exact circumstances under which that warning was given.
These circumstances, as nearly as I can represent them, are shown in Fig. 1. The
images were unsteady, the planet seemed to be approaching geometrical contact, and I
was carefully watching for such phenomena as might present themselves. The images
became more tranquil and I saw a long narrow curved line of light joining the cusps
(Fig. 1). I called " stop," but immediately after doing so I saw that this arc of light
which joined the cusps was not only different in colour from the cusps, but was also of
uniform breadth, and obviously due to the atmosphere of Venus. This was confirmed
by the fact that the cusps continued to approach each other, shortening the arc of light,
but not changing its apparent breadth.
Before the cusps met I lost sight of this ring of light, whether in reality or because
all my attention was concentrated on the point of contact, I cannot say ; and there
appeared between the points of the approaching cusps a dark junction or ligament
which gave to the cusps a slightly blunted form.
20h. 10m. 30s. by Dent. — I cannot be certain whether this is an optical illusion or
not, but I fancy I can see the portion of Venus outside the Sun.
20h. 17m. 30s. by Dent. — My impression that I can see half Venus outside the Sun
is stronger, but the atmosphere of Venus is not visible.
20h. 20m. 0s. by Dent. — I am now tolerably certain that I can see a portion of Venus
outside the Sun's disc.
20h. 25m. 0s. by Dent. — I suspect appearance of atmosphere of Venus.
20h. 25m. 30s. by Dent.— I am certain I see the whole of Venus with " slight halo."
In connexion with the above notes I would add the following remarks.
On further reflection I am inclined to question my conclusion that the dark body of
Venus was really seen outside the Sun. If we consider the process by which the mind
would convince itself that the eye dimly perceived a dark object on a very slightly less
dark background, the form and position of the suspected object being known, we find
that the eye would seek for a contrast of light round the approximately known border
of the dark object, and, if such contrast were found, the mind would be impressed
D 2
22
with the idea that the dark body could really oe distinguished. Now, under the
unfavourable circumstances of definition, the ring of light, produced by the refraction
of sunlight through the atmosphere of Venus, or by illumination of particles in the
atmosphere, was not sufficiently well-defined to be at first objectively distinguished,
but was still sufficiently visible to indicate a difference of shade sufficient to produce
the subjective impressions above described at 20h. 10m. 30s., 20h. 17m. 30s., and
20h. 25m. 0s.
As the critical phase of internal contact approached, Mr. Gamble and Mr. Fry were
cautioned to look out for the simple signal " stop," and to note the nearest second
corresponding to each one of such signals, without any remark.
Three such signals were given by me. and recorded as follows —
Mr. Gamble. Mr. Fry.
Chronometer TJent 1581. Chronometer Molyneux.
h. m. 8. h. m. s.
2. 20 29 54 1 28
3. 20 29 29 1 28 34
4. 20 29 48 1 28 54
Immediately after giving these signals, I entered the times recorded in my note book,
with the following brief notes.
My first " stop " signal was a warning that " contact approaching.' '
At signal 3, this ligament changed from a dark to a grey or light brown colour, or,
from the phase shown in Fig. 2 to that in Fig. 3, much as in the model at time of true
contact. It should be understood that; the ligament did not suddenly become as long
as shown in Fig. 3 ; that figure is intended to represent its length immediately preceding
its disappearance at signal 4.
In model practice, when the air is steady, this latter ligament disappears almost
instantly, but in the present case it formed " a well-marked and persistent discontinuity
in the illumination of the apparent limb of the Sun near the point of contact " till it
disappeared at signal 4, leaving only a pale yellow shade behind which could not be so
defined. In fact I cannot better define the two phenomena at the times I have recorded,
than in Mr. Stone's words which convey the last instructions of the Committee.
" At ingress, if a, c, b, are three small portions of the solar disc of which c is the
nearest to the point of contact, and the illumination at a and b is undisturbed by the
contact, then we say watch a, c, 6, and when c is last seen to be as dark as the outer
edge of the planet, give us the time as accurately as you can."
" But, if, although c has ceased to be as dark as the outer edge of the planet, yet the
illumination of c is distinctly and clearly less than the illumination at a and b, still
watch for last time at which you are perfectly certain that the illumination at c is less
than at a or &."
According to this definition.
At signal 3, c became decidedly less dark than the outer edge of the planet. To
prevent misunderstanding I should add that I am not certain that the ligament was
ever as dark as the outer edge of the planet, the atmosphere of the planet possibly
preventing this being so. But at signal 3, there was a well-marked change of colour
at the point of contact such as one sees in the model immediately after "model"
geometrical contact.
At signal 4, the illumination of c ceased to be distinctly and clearly less than the
illumination at a and b.
Collecting the times relating to the contacts, we have —
h. in. s. h. m. s.
1.
2.
First seen - UO
20
9
28
47* by Dent.
54 ' „
1
1
9
28
5* by Molyneux
o
3.
Ligament changing
colour - - 20
29
29
1
28
34
4.
Disappearance of any
continuous ligament 20
29'
48
1
28
54
We therefore get for times of contacts, taking mean of times given by the two chrono-
meters, except for " first seen " where the two times differ 10s. (nearly). (In this case
the earlier time, that by Mr. Gamble with Dent, has been used.)
* These times differ nearly 10 s ,
Local Sidereal Time.
1.
2.
3.
4.
h. rn. s.
20 7 7-67
20 26 15-10
20 26 49-64
20 27 9-17
Whence the equation s-
23
Ingress.
Local Mean Time.
h. m. s.
3 6 8-70
3 25 13-00
3 25 47-44-
3 26 6-92
Greenwich Mean Time.
h. m. s.
1 52 13-96
2 11 18-26
2 11 52-70
2 12 12-18
1. 4-933 = - 1-658 8w - 8R - 8p +0-525 8a +0-823 SA -0-054 U
2. 0-895 = - 1-722 for - SR + 8 p +0-483 8a +0-852 8A -0-051 ft
3. 2-664 = - 1-723 Stt - 3R + 8p +0-482 8a +0-853 SA -0-051 U
4. 3-655 = - 1-724 St - 8R + Sp +0-411 8a +0-853 SA -0-051 8/,
Observations of the Contacts of the Sun and Venus.
Mr. G. W. H. Maclear.
Observed with the 7-inch equatoreal ; a first surface reflecting prism ; power 184.
Times noted by chronometer, Parkinson and Bouts 801. The times were taken by-
Mr. Coakes.
Ingress.
Sky clear; definition not very good. The time of external contact not noted, my
attention being directed to the driving clock of the equatoreal, which was not working
steadily. I had also been instructed to confine myself to the internal contact.
At 3h. 58m. 49-5s. by chronometer I detected the faint outline of the external
limb of Venus.
At 4h. lm. 40s., the planet's external limb distinctly visible.
At 4h. 2m. 34s., the definition very bad, and image "furry," but I fancied an
appearance of a brownish tinge upon the ligament,
4h. 3m. 135s. by chronometer ; change of colour more apparent.
4h. 4m. 42s. by chronometer ; decided change of colour.
4h. 5m. 25s. by chronometer; Venus appeared to separate from the ligament,
traces of which still remain like broken threads at the Sun's limb.
4h. 6m. 2*5s. by chronometer. At this time all traces of the ligament disappeared.
Collecting the times relating to the contact we have —
h. m. «
1. Decided change of colour - 4 4
2. Venus appeared to separate from
the ligament - - - 4 5
3. All traces of ligament disappeared 4 6
The following corrections of the chronometer have
observatory —
42 by chronometer.
25
2-5
been supplied by the Cape
At 3 22-4 by chronometer; chronometer fast of local mean time 39 42-0
» 4 19 '° » » „ 39 42-1
We therefore get for times of contact —
Ingress.
Chronometer Time.
Local Sidereal Time.
Local Mean Time.
Greenwich Mean Ti
1.
2.
3.
h. m. s.
4 4 42
4 5 25
4 6 25
h. m. s.
20 26 1-99
20 26 45-10
20 27 2271
h. m. s.
3 24 59-93
3 25 42-92
3 26 20-42
h. m. a.
2 11 5-19
2 11 48-18
2 12 25-68
D 3
24
Whence the equations
1. 0-226 = -1-721 ?tt - 8R + 8p +0484 3a +0*852 8 A -0-051 3*
2. 2-427 = -1-723 fa - oR + fy +0*482 3a +0-853 8A -0-051 Sf
3. 4-339 = -1-724 fa - 3R + fy +0-481 Sa +0-854 8A -0-051 Sf
Observations of the Contacts of the Sun and Venus.
Dr. W. L. Blkin.
Observed with half the object-glass of the heliometer of 4*2 inches aperture ; power
180, and a bluish sunshade. The object-glass of the heliometer is, as a whole, extremely
good, each image, however, formed by one-half of the object glass is, of course,
deformed in the direction perpendicular to the line of section, and, as it was considered
advisable to make use of but one of the images, care was taken to place this line
parallel to that joining the centres of Venus and the Sun. Times noted by chrono-
meter Gill.
Ingress.
The afternoon of December 6 was extremely warm and cloudless, but the definition
very poor. The portion of the Sun's limb where Venus was to enter was placed in
the square of wires marking the centre of the field, and at 20h. 4m. 58s. chronometer
time a flattening of this point was perceived, which in seven or eight seconds proved
itself by its permanency to have been caused by the advancing planet. In spite of
the undulations I am inclined to consider the above time to be very little later than
the true contact.
During: the interval between this and internal contact, I devoted mv attention
principally to looking for signs of an atmosphere of Venus, but at no time could I
detect any traces of such. The sky around the notch was perfectly black, as black
as Venus herself, and by no effort could I see anything outside the Sun, which 1 would
not immediately have pronounced to be subjective.
I took the second from the chronometer at 20h. 24m. 0s., and at 20h. 24m. 39s.
chronometer time, I estimated that the prolonged limbs of Venus and the Sun would,
in my opinion, have been tangential ; this is, I believe, the so-called geometrical
contact, but I can place no reliance on the moment noted, for, at that time, the
distance between the blunted cusps of light was still one-third of the planet's diameter,
and the imaginary prolongation of a curved line through such a distance is doubtless
open to large systematic error. The progress of the phenomenon was then to my eye
as follows : — The connection or ligament between Venus and the Sun, I must describe
it as such since the apparent circular outline of the former was quite within the
latter, which, at the moment above given, was quite as black as the planet, became
gradually less deep in tint, diminished in extent, and the cusps lost their rounded-off
appearance, the ends of the ligament changing from a well-defined outline to a gradual
melting away. There was no definite moment that could have been noted until
20h. 25m. 41s. chronometer time, when a well-marked phase occurred. The ligament
from being a band some 10" or 12" long and about one-quarter as broad, variable in
shade and constantly being mixed up by the undulations of the air with the adjacent
darker portions of the planet and the sky, dwindled to a narrow connexion of very
much lighter shade, and not more than a few seconds long, using the term in the
same sense as before, where the meaning is evident. The transition was rapid, I
Bhould say, in almost less than one second, and reminded me vividly of a very similar
phase in the artificial transit which the American party had with them, and I had seen
before in Germany, corresponding, I believe, to an instant very close to the actual
contact of the model. This narrow connexion now faded gradually away, vanishing
at 20h. 25m. 54s. chronometer time, but it was not until a few seconds later that the
space between the planet and the nearest Sun's limb seemed to me quite as bright as
the rest of the Sun's surface, this space being tinged with yellow apparently until
20h. 25m. 59s. chronometer time.
The first impression which the completed observation left on my mind was the
entire absence of any disturbing influence of an atmosphere of Venus, and a dis-
appointment at seeing no signs of any such. If it proves to have been generally seen
under circumstances of considerable atmospheric disturbance, I can only attribute
25
my failure to having used too dark a shade for the high power and small aperture,
although this was the lightest at my disposal and quite as bright as the eye could
support for any great length of time. For this same reason I am inclined to place
very little value on the two last times noted, as the phenomena they purport to fix
must depend greatly on the observer and absorbing medium employed. On the other
hand, the well-marked phase at 20h. 25m. 41s., which I cannot imagine to be radically
modified by the influence of any "halo" or " aureole" afforded the satisfaction of
having seized upon something definite, and which, although previously somewhat
sceptical as to the resemblance of the model phenomena to those of the actual transit,
I immediately recognised as a salient feature of the former under similar circumstances
of atmospheric perturbation.
Collecting the times, we have —
1. External contact -
2. Tangential contact
3. Decided change in ligament
4. Narrow connexion vanished
5. Space between planet and Sun's
limb as bright as remainder of
Suns surface -
We therefore get for times of contacts —
h.
20
4
58 by chronometer.
20
24
39
20
25
41
20
25
54
20 25 59
Local Sidereal Time.
i.
2.
3.
4.
5.
h.
20
20
20
20
20
m.
6
25
26
27
27
14-66
55-60
57-59
10-59
15-59
Whence the equations —
Ingeess.
Local Mean Time.
h.
3
3
3
3
3
m.
5
24
25
26
26
15-84
53-55
55-37
8-34
13-32
Greenwich Mean Time.
h.
m.
S.
1
51
2110
2
10
58-81
2
12
0-63
2
12
13-60
2
12
18-58
1.
2.
3.
4.
SB, - Sp 4-0-527 Sa 4-0-821 SA -0-054 &
8R + S> 4-0-484 3* +0-851 SA -0-051 U
3R _|_ fy 4-0-482 Sa +0-853 SA -0-051 U
8B, + o> +0-481 Sa +0-853 SA -0-051 U
3-983 = -1-724 Stt - Sit + Sp +0-481 Sa +0-853 SA -0-051 Si
2-087
-0-105
3063
3-720
-1-658 &r
-1-721 S;r
-1-723 far
-1-724 fa
Observations of the Contacts of the Sun and Venus.
Mr. J. Freeman.
Observed with a 3^-inch theodolite, diagonal eye-piece ; power 74, times noted by
chronometer Arnold 1167.
Ingbess.
At 2h. 46m.* 18s. by chronometer, I caught sight of first shading of light between
limbs, lighter considerably than "Venus, say a very dark brown tint or even darker ;
I believe this might have been detected earlier, but the boiling just then seemed at its
worst.
At 2h. 46m.* 35s. by chronometer, I concluded that internal contact had taken
place, as a few seconds before, I detected a few breaking up twists of wavy light ;
this again gave place to a steady well-defined very fine line of light, and the cusps or
horns of the Sun, just at this instant, appeared to meet, and form a persistent and
continuous ring of sunlight round the planet. This I took to be the actual time of
contact.
Sky clear, with a light south-east breeze. Both Sun and planet boiling, with no
interval of steadiness, but definition withal of a uniform character.
* 47m. in original ; altered to 46m. in Dr. Gill's report.
D 4
26
We therefore get for times of contacts-
Ingress.
Chronometer Time.
Local Sidereal Time.
Local Mean Time.
Greenwich Mean Time
h. m. s.
. 2 46* 18
;. 9 46* 35
h. m. s.
20 26 54-28
20 27 11-34
h. in. s.
3 25 52-07
3 26 9-08
h. m. s.
2 11 57-33
2 12 14-34
1
2
Whence the equations —
i. 2-891 = - 1-723 8*- -oR -f% +0482 3a +0*853 §A -0-051 &
2. 3-753= -1-724 &r -SB +8p +0-482 8a +0-853 SA -0-0518*
Observations of the Contacts of the Sun and Venus.
Mr. C. R. Pillans.
Observed with a 3^-inch equatoreal ; power 120, with a yellow slide. Times noted
by Mr. M. W. Theal by chronometer Barraud 618.
Ingress.
The time of external contact at ingress was noted by a stop watch at 3h. 6m. 30s. ;
the watch was compared with the chronometer a few minutes before and found to
agree. At the time given, I first saw a slight depression in the Sun's limb. I at once
noted the time, and on examining it more closely, satisfied myself that it was Venus.
At. 3h. 18m. 5s. by chronometer, I saw a ring of light round the planet outside the
Sun's limb, which seemed to vary in brightness several times. The Sun's limb at this
time was very steady, and Venus clearly defined.
At 3h. 19m. 40s. by chronometer, cusps began to form and then die away again, the
definition at this time being very changeable and the Sun's limb very unsteady.
At 3h. 25m. 30s. by chronometer, the black drop was much longer and very unsteady
just before the change of colour.
At. 3h. 25m. 37s. by chronometer, the colour changed to a light yellowish brown,
and remained so for a couple of seconds.
At 3h. 26m. 9s. by chronometer, there was a sudden break off of any shade and a
clear opening appeared between Venus and the Sun ; this was very clearly seen, the
Sun s limb being very steady at the time*
Collecting the times relating to the contacts, we have —
1. External contact
2. Black drop much longer
3. Change of colour
4. Sudden break off of any shade
We therefore get for times of contacts —
h. m. s.
3 6 30 by chronometer.
3 25 30
3 25 37
3 26 9
Ingress.
Chronometer Time.
Local Sidereal Time
h. m. s.
20 7 34-08
20 26 37-18
20 26 44-20
20 27 16-29
Local Mean Time.
Green-
h.
1
2
2
2
wich Mean Time.
h. m. s.
1. 3 6 30
2. 3 25 30
3. 3 25 37
4. 3 26 9
h. m. s.
3 6 35-04
3 25 35-02
3 25 42-02
3 26 14-02
m. p.
52 40-30
11 40-28
11 47-28
12 19-28
Whence the equations —
r
1. 6-342 =
2. 2-014 =
3. 2-382 =
4. 4-015 =
-1-658 &r -8R -op +0-5248« +0-823 8A
-1-723 oY -8R +8p 4-0-483 Sa +0-852 8A
-1-723 6V -8R +8p +0-482 8« +0-853 8A
-1-724 8v -8R +6> +0-481 8« +0-853 8A
-0-054 U
-0 051 U
-0 0518^
-0-051 8*
47m. in original ; altered to 46m. in Dr. Gill's report.
27
Observations of the Contacts of the Sun and Venus.
Captain M. Jurisch.
Observed with a 2|-inch telescope by Reinfelder and Hertel, Miinohen ; power 135.
The telescope shows Orionis as a double star ; on nights of good definition Saturn's
rings can be seen, consisting of two, and the rice grains on the Sun are visible on days
of good definition. Times noted by chronometer Murray 753.
Ingress.
At 3h. 7m. Os. by chronometer, I first noticed the planet, flattening as it were, the
protruding parts of the somewhat agitated limb of the Sun at the exact spot at which
I expected the planet to appear on the Sun's limb. 1 think this record of the time of
external contact will not be late by more than five or six seconds.
3h. 25m. 35*5s. by chronometer. The disc of the planet, mentally completed, seems
to touch the limb of the Sun. The black space between the cusps presents an appear-
ance as if some black liquid were filling the thinnest parts of the cusps by adhesion to
both the planet's and the Sun's limbs.
3h. 26m Is. by chronometer. The space between the cusps changes its black colour
into a brownish tinge.
3h. 26m. 17*5s. by chronometer. Disappearance of any marked and persistent discon-
tinuity in the illumination of the Sun's limb. This time record may be three or four
seconds late, since I was doubtful for three or four seconds whether there was, or was
not, discontinuity ; the brownish tinge between the cusps becoming gradually
brighter.
The chronometer correction as supplied in Dr. Gill's report is —
At 3h. 47*7m. by chronometer. Chronometer fast of local mean time "' 2'5s.
No rate given.
We therefore get for the preceding contacts — ■
Ingress.
Chronometer Time.
Local Sidereal Time.
Local Mean Time.
Greenwich Mean Tin
h. m. s.
h. m. s.
h. m. s.
h. m. s.
1. 3 7
20 7 56-60
3 6 57-50
1 53 2-76
2. 3 25 35-5
20 26 35-15
3 25 33-00
2 11 38-26
3. 3 26 1
20 27 0-73
3 25 58-50
2 12 3-76
4. 3 26 17-5
20 27 17-27
3 26 15-00
2 12 20-26
Whence the equations —
1. 7-546 = -1-658 he -811 -6> +0-523 8a +0-824 8A -0-054 8*
2. 1-914 = -1-723 83- -8R +8p +0-483 8a +0-852 8A -0-051 U
3. 3-216= -1-724 for -8R +8p +0-482 8« +0-853 8A -0-051 8*
4. 4-063= -1-724 8^- -8R +8 P +0-481 8« +0-853 8A -0-051 U
STRAIT OF MAGELLAN.— STRAIGHT-ARM STATION, PECKETT
HARBOUR.
h. m. s.
Longitude of station - - 4 43 13-65 W. of Greenwich.
Latitude „ - - 52 46 27-0 S.
Observations of the Contacts of the Sun and Venus.
Captain W. J. L. Wharton, R.N.
Observed with a 4-inch refractor, Simms' detached No. 1 of the Royal Observatory,
Greenwich; power 145. The definition of the instrument is by no means good.
Sun spots were numerous a few days before the transit, and afforded an excellent test,
a 22653. E
28
but on no occasion could I get a sharp image. I could see the mottling of the Sun's
disc, but could, scarcely say that the rice grains ever assumed any definite form, the
image not being clear enough. On the day of the transit the Sun was as clear as
possible, and I saw a bright mass of f aculse near the limb as distinctly as I saw any-
thing with the telescope ; powers of 200 and 79 were supplied, and an Airy eye-piece
of power 145. As I found I could get the best definition with this latter, and as it
was nearly of the power mentioned in the " Instructions to Observers/' I used it for
the observation. It was fitted with a neutral tint wedge. I used the same portion of
the wedge that I had found by experiment beforehand gave the best tint to a clear
Sun, i.e., about one-third from the darker end, which is about the same degree of
shade with which I am accustomed to observe the Sun on all occasions, and which
gave a clear limb with no glare whatever. The telescope, as well as the one used by
Lieut. Havergal, was mounted temporarily equatoreally, as the vertical slow motion
was so coarse that I was greatly afraid of not being able to keep Yenus in the centre
of the field at the critical moment if it had to be used, whereas the other motion was
both slow and steady. This arrangement greatly facilitated the observation. A small
spot on the Sun served well for focussing. Times noted by chronometer Loseby 113,
by Lieut. A. M. Field, K.K
Ingress.
First saw Venus. External contact passed probably a minute, 2h. 0m. 26s. by
chronometer.
Aureole first seen on following quarter of outer limb of Yenus, 2h. 12m. 23s. by
chronometer.
Aureole all round outer limb, 2h. 15m. 0s. by chronometer.
G-eometrical contact nearly. Aureole visible in line with Suns limb, 2h. 19m. 9'8s.
by chronometer.
Last appearance of well marked and persistent discontinuity in illumination of Suns
limb, 2h. 19m. 39'0s. by chronometer.
Last distinct appearance of atmospheric tremor, 2h. 19m. 43*0s. by chronometer.
The aureole round Yenus was very plain, but was not to me so well defined as in
1874, probably on account of the bad definition of the telescope.
At geometrical contact which was not well defined on account of the haziness of the
aureole, the latter showed on the Sun's limb.
Instantly after Yenus was apparently inside the Sun's limb, but a blackish haze
joined the planet to the outer darkness. This haze remained of the same width near
Venus, but at the Sun's limb the light of the cusps seemed to run in and join very
rapidly. This meeting of the cusps I give as the critical phenomenon of last
appearance of well-marked discontinuity of the Sun's limb, and should be correct to
two seconds.
The haze remained a little longer, but attenuated in its apparent density, and
seemingly connected to Yenus only. The time I give of last atmospheric appearance,
its duration may have been a few seconds greater.
Sun's edge good, but definition of telescope generally poor.
Eight seconds after ingress the Sun was clouded.
Yenus on the Sun appeared perfectly round.
In the interval between ingress and egress there were sometimes many clouds, at
others, clear sky. Just before egress there was a long nimbus, with a heavy fall of
rain, but it moved on and left the sky perfectly clear.
Egress.
First appearance of slight atmospheric tremor, 7h. 57m. 46*7s. by chronometer.
First appearance of well-marked persistent discontinuity in the illumination of the
Sun's limb, 7h. 58m. 17'8s. by chronometer.
Geometrical contact as at ingress, 7h. 58m. 36 # 0s. by chronometer.
External contact between 8h. 18m. 23'0s. and 8h. 18m. 27*0s. by chronometer.
The atmospheric tremor first noted was a faint one, and it lasted some time before
any real discontinuity of the Sun's limb was detected.
The critical phenomenon was not quite so well-marked as at ingress, but is probably
correct to two seconds.
G-eometrical contact was not so well observed as at ingress* the aureole again
interfering.
29
Sun's edge quiet, but definition poor. Clouds covered the Sun about two minutes
after egress, and just opened to let me see the external contact.
The movement of Venus across the Sun's limb was markedly more rapid than in
1874, so much so that I have no hesitation in saying that the critical phenomenon was
twice as easy to determine as it was in the last transit, though, perhaps, the knowledge
of what to expect, and the recollection of the long lingering contact of 1874, may have
helped to make the contrast greater than it really was.
I devoted my whole attention to the Sun's limb near the point of contact, to observe
the critical phenomenon as defined in the " Instructions," and, though I noted both
geometrical contacts and the last atmospheric tremor at ingress and the first at egress,
the bad definition of the telescope rendered all very doubtful.
Collecting the times relating to the contacts, we have —
Ingress.
1. First seen -
2. Geometrical contact nearly -
3. Last appearance of well marked
and persistent discontinuity
4. Last distinct appearance of atmo-
spheric tremor -
h.
2
2
m.
19
26 by chronometer,
9-8
2 19 390
2 19 43-0
Egress.
7.
8.
First appearance of slight atmo-
spheric tremor
First appearance of well marked
and persistent discontinuity - 7
Geometrical contact as at ingress - 7
External contact between these T8
times - - - - \ 8
7 57 46*7 by chronometer.
58
58
18
18
17-8
36-0
18-0
23-0
We therefore get for times of contacts-
Local Sidereal Time.
h. m. s.
1. 14 13 29-54
2. 14 32 16-62
3. 14 32 45-90
4. 14 32 49-91
Local Sidereal Time.
5.
6.
7.
h.
20
20
20
f20
L 20
m.
n
12
12
32
32
48-95
20-13
38-38
23-61
28-62
Whence the equations —
Ingress.
Local Mean Time.
h. m.
S.
21 12
30
21 31
14
21 31
43-20
21 31
47-20
Egress.
Local Mean Time.
h. m.
S.
3 9
50-70
3 10
21-80
3 10
40-00
("3 30
22-00
3 30
27-00
Greenwich Mean Time.
h.
m.
S.
1
55
43-65
2
14
27-65
2
14
56-85
2
15
0-85
Greenwich Mean Time.
h.
m.
S.
7
53
4-35
7
53
35-45
7
53
53-65
"8
13
35-651
8
13
40-65 J
Ingress.
1. 6-864 =
2. 1-840 =
3. 3-339 =
4. 3-549 =
- 0-625 3?r
- 0-745 3tt
- 0-749 Stt
- 0-749 or
8R
SR
§R
m
+ op
B
+0-536 3«
+0-496 §«
+0-495 3«
+0-495 8a
+0-814 3A
+0-843 3 A
+0-844 3A
+0-844 3A
-0-054 U
-0-051 U
-0-051 U
-0-051 ti
30
Egress.
5. 6-161
6. 7769
7. 8-713
8.*7-334
0-436 oV
0-440 ojt
0-443 as-
0-615 oV
+ oR — op
-j- oR — op
+ §R — op
+ 8R + o>
4-0-830 6a
+0-831 8«
+0-831 3a
+0-851 Oa
-0-438 oA -0-052 o*
-0-436 SA -0-052 U
-0-435 8A -0-052 8«
-0-387 8 A -0-054 U
STRAIT OF MAGELLAN.— SANDY HILL STATION, PECKETT HARBOUR.
Longitude of station
h. m. s.
4 43 4-35 W. of Greenwich.
Latitude
52 47 23-4 S.
Observations of the Contacts of the Sun and Venus.
Lieut. A. Havergal, R.N.
Observed with a 4-inch refractor, Simms' detached No. 2 of the Royal Observatory,
Greenwich ; power 150. The lens of the telescope does not appear to be of the best
quality, as it exhibits a great deal of colour in the Sun's limb. The eye-piece, the
private property of the observer, gives excellent definition. "Rice grains" were
clearly visible on the day of the transit, but with no definite form. The prismatic
reflector and neutral tint wedge were used, the latter about a quarter of the way from
its lightest end, and which remained unaltered during the observations. Times noted
by pocket chronometer Molyneux 2097 by Lieut. H. B. Anson, R.N.
Clouds prevented any observation.
Ingress.
Egress.
Slight disturbance on the outer limb of Venus without any definite shape, light
yellowish haze, 6h. 45m. 29-6s. by chronometer.
Disturbance assumed a definite form or ligament, 6h. 49m. 39-2s. by chronometer.
First appearance of persistent and well marked discontinuity in the Sun's limb
6h. 49m. 52*8s. by chronometer. '
First appearance of aureole, 6h. 50m. 10s. by chronometer.
I consider the conditions satisfactory ; a smart shower having fallen a few minutes
before the time of contact, the surrounding atmosphere was clear, and the definition
good.
My impressions of the approach of the contact were those of being agreeably
disappointed at finding so little " boiling " or atmospheric tremor, and this is perhaps
more remarkable as I used a lighter part of the wedge than I originally intended,
having, in my anxiety not to miss any phase in the phenomenon, omitted to move it
to a darker portion after the Sun came out from the clouds.
The " slight disturbance " (6h 45m. 29-6s.) was when I first noticed the appearance
of a light brown and yellowish haze on the outer limb of Venus, which took place
roughly speaking, when she was about her own diameter within the Sun's limb • it
had no definite form, but seemed to increase in extent as the planet approached the
point of contact until 6h. 49m. 39-2s., when a light, band or ligament formed through
which, however, the sunlight was distinctly visible, and the limbs of both Sun and
planet continuous. This ligament continued to get darker, and at 6h. 49m. 52-8s I
considered that a " well marked and persistent discontinuity " was first established
and is the only time I should give for contact were I restricted to a single term
The aureole first appeared immediately after the limb of the planet had' passed
that of the Sun ; it did not appear to me steady, but as intermittent flashes of
sunlight.
The external contact was obscured by clouds.
* Mean of times.
31
Collecting the times relating to the contacts, we have —
Egress.
h. m. s.
1. Disturbance assumed a definite
form or ligament - - 6 49 39*2 by chronomeier.
2. First appearance of "persistent
discontinuity" - - - 6 49 52*8
We therefore get for times of contacts —
Egress.
Local Mean Time. Greenwich Mean Time.
Local Sidereal Time.
1.
2.
h. m. s.
20 12 8-57
20 12 22-21
h. m. s. h. m. s.
3 10 1030 7 53 14-65
3 10 23-90 7 53 28-25
Whence the equations —
1. 6-689 = 0-437 &r 4- 8R - 8p +0-830 8a -0437 8 A -0-052 8*
2. 7-398 = 0-439 8tt + 8R — 8p 4-0-830 8a -0-437 8A -0-052 U
BARBADOS.— HASTINGS.
h. m. s.
Longitude of station - 3 58 22-85 W. of Greenwich.
Latitude „ - - 13 4 25'9 N.
Observations of the Contacts of the Sun and Venus.
Mr. C. G. Talmage.
Observed with a 6-inch equatoreal by Cauchoix ; power 158. Times noted bv clock
Dent 2017. J
Ingress.
When bisected, limb of Venus surrounded by a white light, 15h. 9m. S.T.
15h. 17m. 40s. by clock. Venus entirely visible on and off the Sun ; white light
round following limb.
15h. 24m. 55*2s. by clock. The time of last appearance of a well-marked and
persistent discontinuity in the illumination of the npparent limb of the Sun.
This time I consider exact. Definition good ; no black drop, and phenomenon
was instantaneous.
The granular markings on the Sun were clearly visible all the morning.
(Clock comparison follows.)
I attempted no double-image micrometer observations. Many clouds were flying
about, and I determined to run no risk.
Barometer 30*10 inches ; Thermometer 86°*5 F.
There was not the slightest appearance of any contact after time given.
Egress.
At 20h. 43m. I noticed a bright gold (?) coloured mark on the following limb of
Venus.
20h. 51m. 14s. by clock. Limbs boiling violently. Quite sharp ; different from
model when Sun's east ?> more like model Sun west. ' (I mean by this that at Oxford
the appearances were different when Sun shone on or was behind model).
20h. 57m. 0s. Sunlight much more visible on N. than on S. limb of Venus ; called
Thomson's attention to this.
E 3
32
21h. 11m. 41s. by clock. Limbs boiling violently. I consider this time doubtful
to three or four seconds. It was the most difficult observation of the series. Clouds
constantly passing, but at the moment the Sun was quite clear. The Sun was over
the sea, and we had to look through the heated air of the town.
Collecting the times relating to the contacts, we have —
1. Persistent discontinuity
Ingress.
Egress.
2. Internal contact -
3. Last contact
We therefore get for times of contacts —
Ingress.
h. m. s.
15 24 55-2 by clock.
h. m. s.
20 51 14 by clock.
21 11 41
Clock Time.
Local Sidereal Time.
Local Mean Time.
Greenwich Mean Tin
1.
h. m. s.
15 24 55-2
h. m. s.
15 24 44*04
Egress.
h. m. s.
22 23 40-18
1). in. s.
2 22 3-03
Clock Time.
Local Sidereal Time.
Local Mean Time.
Greenwich Mean Tin
2.
3.
h. m. s.
20 51 14
21 11 41
h. m. s.
20 50 59-08
21 11 25-98
h. m. s.
3 49 1-77
4 9 25-32
h. m. s.
7 47 24-62
8 7 48-17
Whence the equations —
1.
2.
3.
Ingress.
1-631 = 1*843 8tt - SB, + 8p +0-467 8a +0*863 8 A -0-050 U
Egress.
8-122 = -2-571 8tt + 8R - 8p +0-815 8a -0-469 8A -0-050 U
6-902 = -2-641 8tt + SR + 8p +0-839 8a -0*417 8 A -0-053 U
Observations of the Contacts of the Sun and Venus.
Lieut. J. H. Thomson, R.A.
Observed with a 6-inch Simms' equatoreal, positive eye-piece; power about 180.
Times noted by clock Dent 2016.
Ingress.
Owing to passing clouds and bad definition I did not see Venus on the Sun's disc
until 15h. 5m. 12*0s. by clock Dent 20 L6. External contact had then taken place
about 75s., judging from the time taken by the planet at egress in passing from a
similar phase to external contact. As Venus advanced on the limb of the Sun I had
to be continually moving the wedge in order to retain a constant brightness of the
field. At 15h. 20m. 49s., when the field suddenly increased in brightness, I saw the
whole circumference of Venus, the limb outside the Sun's disc being surrounded by a
beautiful halo of white light and sharply defined. At about the same time the cusps
appeared slightly blunted and bent outwards. As interior contact approached the
Sun cleared, and in a moment of good definition I saw geometrical contact at
15h. 24m. 24'Os. by clock. Immediately after this clouds began to pass, and there
was a great deal of boiling and dancing. There seemed to be a discontinuity in the
illumination of the Sun's limb for upwards of a minute after, but it did not seem as
33
dark as the disc of the planet. At about 15h. 25m. 30s. the Sun was completely
obscured, and at 15h. 25m. 58s., when it reappeared, Venus was completely on its
disc, being distant from the limb about the interval of the broader of the two pairs of
wires in my eye-piece.
Egress.
At egress there was less trouble from, the clouds, and the definition was better,
although the Sun was lower. I first saw a well-marked and persistent discontinuity
in the illumination of the Sun's limb near the point of contact at 20h. 50m. 24'Os. by
clock. At 20h. 50m. 38*0s. this became as dark as the disc of the planet, and
geometrical contact occurred at the same time. After interior contact light was
visible round the outer limb for some time, but it did not completely surround the
planet, extending further on the northern side than on the southern. The cusps
appeared bent out, but not so much blunted as at ingress.
Exterior contact was very good. I last saw the planet at 21h. 11m. 15'0s. by
clock.
Collecting the times relating to the contacts, we have —
Ingress.
h. m. s.
1. First seen - - - - 15 5 12*0 by clock.
2. Apparent geometrical contact - - 15 24 24*0 „
Eeal internal contact lost through clouds.
Egress,
3. Persistent discontinuity
4. Geometrical contact, shadow as black
as planet -
5. Exterior contact - - - -
We therefore get for times of contacts —
Ingress.
h.
20 50 24-0 by clock.
20 50 38-0
21 11 150
Clock Time.
Local Sidereal Time.
Local Mean Time.
Greenwich Mean Tii
1.
2.
h. m. s.
15 5 12-0
15 24 24-0
Clock Time.
h. m. s.
15 5 27-59
15 24 39-60
Egress.
Local Sidereal Time.
h. m. s.
22 4 26-89
22 23 35-75
Local Mean Time.
h. m. s.
2 2 49-74
2 21 58-60
Greenwich Mean Ti
3.
4.
5.
h. m. s.
20 50 24-0
20 50 38-0
21 11 150
h. m. s.
20 50 39-82
20 50 53-82
21 11 30-84
h. m. s.
3 48 42-56
3 48 56-52
4 9 30-16
h. m. s.
7 47 5-41
7 47 19-37
8 7 53-01
Whence the equations —
1.
2.
6-566 =
1-417 =
1-929 3*-
1-843 ox
Ingress.
SR _ Sp +0-511 8a +0-833 8A -0-052 ti
8R + Sp +0-467 8a +0-863 SA -0-050 U
Egress.
3. 7-155 = -2-571 St + 8R - Sp +0-815 8a -0-470 8A -0-050 U
4. 7-859 = -2-571 3tt + 8R - 8p +0-815 8a -0-469 8A -0-050 U
5. 7-155 = -2-641 8tt + 8R + Sp +0-839 8a -0-416 8A -0-053 U
B 4
34
JAMAICA.— UP PARK CAMP.
h. m. s.
Longitude of station - - 5* 7 8*35 W. of Greenwich.
Latitude „ - 17 59 25*4 N.
Observations of the Contacts of the Sun and Venus.
R. Copeland Ph. D.
Observed with a 6-inch Simms' equatoreal with a negative eye-piece ; power 1 60.
Times noted by chronometer Walker 171.
Ingress.
At 19h. 4m. 9-0s. by chronometer, just perceptible notch in the Sun's bmb. One
minute later the notch was very deep. Aureole brighter to S. very obviously so at
19h. 15m.
Intense aureole at 19h. 22m. 3O0s.
Nothing like contact so early as 19h. 24m. 25*0s.
First steady flow of light between limbs at 19h. 24m. 35 '0s. by chronometer.
At 19h. 24m. 49'Os. very wide lane.
Nothing like a ligament.
The unsteadiness of the images produced a black lenticular figure just at the point
of ingress.
At 19h. 35m. by chronometer, the following remarks were added in amplification of
the above.
Up to 19h. 24m. 25*0s. nothing that could in any way be confounded with internal
contact had taken place. The bright line or aureole round Venus was indeed visible,
but it was not nearly so bright as the Suns disc. At 19h. 24m. 25s., or a second or
two later, a certain regularity in the undulations of the image of Venus set in and
produced a dark lenticular figure just at the point of contact ; this interfered in some
degree with the regularity of the phenomenon, but still the first flow of the direct
Sun's light round Venus could be set down as occurring at 19h. 24m. 35*0s. by
chronometer. This time was entered as that of internal contact. 19h. 24m. 49*0s. is
merely set down as an epoch most certainly after the contact. Nothing presenting
the appearance of a ligament was seen.
Egress.
At Oh. 12m. (by chronometer) clouds came over; the Sun cleared fairly at Oh. 33m.
b. m. s.
Up to 50 0-0 (by chronometer). Line of light very distinct.
„ 50 7*0 „ Line of light uncertain.
„ 50 9*0 „ Line of light gone.
At Oh. 50m. 29-0s. by chronometer, the aureole was seen very considerably bulged
out, so that contact was certainly over. Had I not known the nature of the aureole
I might possibly have set the contact somewhat later ; but, as matters stand, I believe
Oh. 50m. 9s. by chronometer to be a reliable observation of contact.
(The above was written before lh. by chronometer.)
At lh. Om. Os. aureole very distinct on S. side through an arc of 60°, nearly touching
Sun at one end and running out into a bright point at the other.
From lh. 4m. to lh. 9m. aureole was seen as a detached arc.
lh. 10m. 33s. by chronometer last contact seen as persistent indentation amongst
the ripples on the limb.
lh. 11m. 30s. aureole still seen, then lost sight of it, and could not find it ap-ain
Width of aureole about 1". 5
The aureole was best seen with the pale end of the wedge, but it was nevertheless
visible through even the dark end of the wedge.
35
Collecting the times relating to the contacts, we have-
Ingress.
1. First notch in Sun's limb
2. First flow of the direct Bun's light round
Venus -----
Egress.
3. Line of light gone (the aureole only
remaining) - - -
4. Last contact -
We therefore get for times of contacts —
Ingress.
h.
19
m. s.
4 9*0 by chronometer.
19 24 35-0
h. in.
50 9*0 by chronometer.
1 10 33-0
Chronometer Time.
Local Sidereal Time.
Local Mean Time.
Greenwich Mean Tim*
h. m. a.
1. 19 4 9-0
2. ; 19 24 350
h. m. s.
13 57 2-87
14 17 28-94
h. m. s.
20 56 2-11
21 16 24-83
h. m. s.
2 3 10-46
2 23 3318
Egress.
Chronometer Time.
Local Sidereal Time.
Local Mean Time.
Greenwich Mean Tim<
h. m. s.
3. 50 90
4. 1 10 33-0
h. m. 8.
19 43 3-21
20 3 27-33
h. m. s.
2 41 5-76
3 1 26-53
h. m. s.
7 48 1411
8 8 34-88
Whence the equations—
Ingress.
1. 4*539= 2-278 Stt - 8R - 8p +0-514 8a +0-831 SA -0-052 8*
2. 2-941= 2-195 for - 8R + 8p +0-467 8a +0-862 8A -0-050 8*
Egress.
3. 8-119= -2-295 8?r + 8R - 8p +0-814 8a -0-472 8A -0-050 8*
4. 7-068 = -2-384 8tt + SR + 8p +0-838 8a -0-420 8A -0-053 8*
Observations of the Contacts of the Sun and Venus.
Captain G. Mackinlay, R.A.
Observed with a 6-inch equatoreal ; power used 163. Times noted by mean time
clock Dent 2010.
Ingress.
Watched for and saw an indentation of the limb of the Sun among the slight
ripples on its edge. Waited some 10 seconds to make quite sure that it was really
caused by the planet, and that it was not mere tremor ; saw it gradually increase in
size. Time of first observing this 20h. 56m. 40s. by clock.
At 21h. 4m. light round the south pole ; about 21h. 8m. light stealing all round.
Light distinctly seen all round at 21h. 10m. 20s.
At 21h. 16m. 40s. nearly " contact,'' when I gave a tap to Bombardier McCulloch
to make sure of the minutes, after this time, when limbs of Sun and Venus were first
clear of each other. When there was first a permanent discontinuity between the two
21h. 17m. 0s. by clock. This last I considered " internal contact." No black drop,
but a gradual shading round Venus at contact, when limbs of Sun and planet were
clear of each other ; both were perfectly sharp and defined.
Egress.
First permanent attachment of limbs of Sun and planet observed at 2h. 41m. 49s.
by clock. This I considered " internal contact." Appearances similar to those at
a 22653. F
36
internal contact at ingress, but definition not so good, limbs of Sun and planet
quivering, not so much of the shading or illuminated atmosphere round Venus visible
as at ingress.
At 2h. 49m. aureole appeared. At 2h. 56m. aureole seen faintly only if light part
of the wedge is used ; not half round planet ; one-third way round.
Last appearance of the following limb of Venus among the ripples on the edge of
the Sun observed at 3h. 2m. 3s. by clock. Possibly it vanished three or four seconds
before, but this is the best estimate I can give ; the limb of the Sun quivered a good
deal, but I believe I traced the indentation caused by the planet as long as stated.
I purposely refrained from giving several times at each contact so as to avoid
possible confusion. The internal contacts did not resemble the model, except in their
lingering nature.
At ingress clear uncloudy sky ; definition good ; granulations of Sun visible. Half
an hour before egress a few clouds crossed the Sun, but cleared off, leaving the sky
clear ; definition however] not so good as at ingress, and granulations not easily
visible.
At ingress, egress, and also two days after in the transit instrument, it was noted
that the south pole is illuminated.
The planet appeared quite round ; no satellite seen.
The clock driving the hour circle failed to act shortly before egress, but the R A.
slow motion screw was used to follow the Sun and planet.
Collecting the times relating to the contacts, we have—
Ingress.
1. An indentation in the Sun's limb
2. Permanent discontinuity
h.
m.
S.
- 20
56
40 by
clock
- 21
17
»
Egress.
3. First permanent attachment of limbs of
Sun and planet - -
4. Last appearance of Venus among the
ripples on the Sun's edge
2 41 49 by clock.
3 2 3,,
We therefore get for times of contacts —
Ingress.
Clock Time. Local Sidereal Time. Local Mean Time.
Greenwich Mean Time.
1.
2.
h. m. s.
20 56 40
21 17
h. m. s.
13 56 52-69
14 17 16-08
h. m. s.
20 55 51-96
21 16 12-00
h. m. s.
2 3 0-31
2 23 20-35
Egress.
Clock Time.
Local Sidereal Time.
Local Mean Time.
Greenwich Mean Time.
3.
4.
h. m. s.
2 41 49
3 2 3
h. m. s.
19 42 58-44
20 3 15-69
h. m. 8.
2 41 100
3 1 14-93
h. m. s.
7 48 9-35
8 8 23-28
Whence the equations —
1. 4-009 =
2. 2-310 =
2-278 oV
2-196 Stt
Ingress.
8R -o> +0-514 8a +0-830 8A -0-052 U
8R +8 p +0-468 8a +0-862 8A -0-050 8*
3.
4.
7-888 =
6-445 =
Egress.
2-295 8tt +8R -8* +0-814 8a +0-472 8A -0-050 U
2-384 8*- + 8R + 8p +0-838 8a +0-420 8A -0-053 8*
37
JAMAICA.— CHERRY GARDEN, NEAR KINGSTON.
The longitude of the station obtained from two comparisons of Dr. Pearson's chrono-
meter with the Up Park camp sidereal clock makes the Cherry Garden station <>90s. E.
of Up Park camp.
The longitude is therefore —
h. m. s.
5 7 7-45 W. of Greenwich.
The latitude was determined by meridian altitudes of the Sun, a Piscis Australis and
a Eridani, though from the nature of the instrument not with any great precision,
and verified by the known distance from the lighthouse, a few miles to the E. of Port
Royal, bearing one degree (true) East of South, at a distance of about seven miles.
The observations vary between 18° 21' and 18° 3f N., giving most weight to the stars ;
the adopted latitude is —
18 3 20 N.
Observations of the Contacts of the Sun and Venus.
Dr. J. B. Pearson.
Observed with a 3^-inch telescope by Secretan of Paris, coated on the inner side
with a silver film, which was found quite sufficient to reduce the brightness of the Sun,
•when employed as it was with a diagonal eye-piece. The mounting, eye-pieces, and
micrometer were by Simms, and I can take no exception to any part of the instrument.
Unfortunately, I did not receive in time an eye-piece, power 120, constructed on
principles designed to meet the difficulty under which I labour from shortness of sight,
but I am not prepared to say that it would have actually removed the indistinctness
which certainly I noticed with the power used, viz., 135, for which I cannot entirely
account, but which I am sure was not enough to affect the apparent time of contact,
at any rate more than two or three seconds, within which limit similarly situated
observers seldom agree. I saw nothing like an atmosphere round Venus, though I
looked carefully for it, possibly my telescope, considerably smaller than what I may
call the authorised size, would not be large enough to show it. At the same time it is,
as far as I can tell, tolerably achromatic. And I will take this opportunity of mention-
ing a phenomenon, possibly somewhat of a similar nature which I have observed here
more than once. The sun can be seen to set behind a ridge of hills perhaps 30 miles
distant. When viewed through the telescope at an elevation of about one degree
above the crest of the hills, the lower limb is of an orange tint, the sides of the Sun's
ordinary colour, and the upper limb green ; these tints continuing as the two limbs
successively disappear beyond the hills which are often quite free from any cloud or
haze. I do not recollect having seen the phenomenon described in any book, nor am I
sure of its explanation. (Times taken by a watch which Dr. Pearson held in his hand
and which was compared with his standard chronometer directly after each contact.)
Ingress.
The first external contact I missed in a way which can be easily explained. Though
constantly observing the Sun for altitude I have seldom examined its features, and so
failed to notice that a point on its disc 145 E. of N. from the pole, the predicted place
of contact would be at 9 a.m., slightly to the right, and not to the left of the lowest
point of the Sun's limb. Having been indisposed for three days previously, and not
willing to expose myself in observing, I had rather put my preparatory work aside
and thus failed to look through the question in the way I might have done had I been
quite ready for any kind of work.
When I saw Venus first she had intruded about one-third of her disc upon the Sun's
sphere ; I watched her carefully until the two limbs were very nearly in contact, from
which time I did not remove my eye until the Sun's light appeared to surround the
planet, the moment of this phenomenon I fixed at
h. m. s.
1. 21 16 26 Local mean time,
or perhaps two or three seconds later. I noticed no kind of black drop or sympathetic
F 2
38
attraction or assimilation between the limb of the planet and that of the Sun, or rather
the edge of the atmosphere enclosing the Sun. If the want of definition from
which my vision suffered, be it due to my own eyes, my eye-piece, or my object-glass,
allows me to give any formulated description of the first internal contact, I should say,
that when the planet was actually projected on the Sun's disc, say 20 seconds before
the time I assign for actual contact, the surface of the planet adjoining the atmosphere
began to be picked out with little white dots, commencing very probably from either
side, but, as the phenomenon was new to me, I cannot say whether the white spots
began at the two ends of the incomplete segment of the planets disc, or whether they
began throughout at once. I cannot say that I saw two cusps of light gradually
advancing until their points actually touched, but rather, as I have said, that the
segment of the planet nearest to the atmosphere, and still obscure, began to be speckled
with white dots, which in not more than 20 or 25 seconds at the outside developed into
a white line.
"When the planet was well advanced on the Suns disc she was well-defined in her out-
line, and no remarkable difference presented itself at lOh. 52m. a.m., when I took a
measure of her distance from the Sun's edge. But, at noon, when the distance of the
centres of the Sun and Yenus was the least, the irregularity of her disc, from the boiling
of the surrounding solar light, was very marked, and had increased at lh. 35m. p.m.,
when I think it was at its maximum.
Egress.
I had little or no hesitation as to the time of the second internal contact. Perhaps
the outer edge of Yenus was too disturbed to exhibit the minute spots which I seemed
to observe in the morning. But still the planet seemed to descend fairly upon the
atmosphere without any mutual attraction of any kind, and though the planet's disc
did not then appear to the eye anything like a perfect curve or sphere the actual
contact seemed extremely regular, and I do not think that I had any hesitation as to
when it actually occurred, viz., at —
h. m. s.
2. 2 41 2 local mean time.
I was not so fortunate as I might have been in taking off the last external contact.
Owing to a mishap to my chronometer in the morning, I depended for my time on my
watch, which I held in my hand, but just before the last contact, through inadvertence,
I had allowed the planet to get too near the edge of the telescope to be viewed as it
should be, so I took hold of the slow motion handles to bring her more into the field of
view ; moving the telescope in this way causes a slight tremor in the telescope itself,
and when this had passed off the indentation caused by the planet's disc on that of the
Sun had all but disappeared, and I could not feel perfectly confident within two or
three seconds when the actual disappearance was complete. Still, I am sure there can
be no great error about the time I give —
h. m. s.
3. 3 1 15 local mean time,
as the vanishing segment of the planet had only a partial resemblance to the undula-
tions on the edge of the Sun, especially as the momentary apprehensions which I felt
do not seem justified by the result. Had the period I assumed between the third and
fourth contacts been too long a mistake would be probable, but as it was 11 or 17
seconds shorter than the computed time, and, as I am sure that the Sun's disc had
entirely recovered its normal outline at the time I noted, I think that my observation
may be taken as generally exact. Moreover, the longer the period of transit the
shorter will be the passage across the Sun's limb, and as my own period of transit is
as long as that computed by the French and two minutes longer than that given in the
Nautical Almanac, I may be satisfied with the fact that my passage across the disc is
shorter than that anticipated by either of these authorities.
Collecting the preceding times, we have —
Ingress.
Local Mean Time. Local Sidereal Time. Greenwich Mean Time.
h. m. s. h. m. s. h. m. s.
1. 21 16 26 14 17 3011 2 23 3345
39
Egress.
Local Mean Time.
Local Sidereal Time.
Greenwich Mean Time
h. m. s.
2. 2 41 2
3. 3 1 15
h. m. s.
19 42 59-44
20 3 15-76
b. m. s.
7 48 9-45
8 8 22-45
Whence the equations —
Ingress.
1. 2-942 = 2-197 &r -SR +S> +0467 8a +0-8628A -0-0508*
Egress.
2. 7-893= - 2-295 o> +8R -8p +0-814 3a -0-4728A —0-050^
3. 6-403 = — 2-384 8tt +8R +8p +0-838 8a -0*4208A -0-0538*
JAMAICA.— KEMPSHOT OBSERVATORY, MONTEGO BAY.
The longitude of the station was obtained by determining telegraphically, on
November 28 and 29, the difference between Kempshot Observatory at Montego Bay
and Lord Rodney's statue, Dr. Copeland observing at the latter place.
Two chronometers were compared with the standard clock of the observatory, and
then carried to the telegraph office at Montego Bay, signals were exchanged with
Dr. Copeland by both chronometers, which were carried back to the observatory, and
again compared. Unfortunately the weather was unfavourable at Montego Bay, no
observations being obtained between November 29 and December 3, and the going of
the standard clock most irregular ; also some accident happened to one of the
chronometers on November 29, so that the determination is not so reliable as could be
wished. The result is —
h. m. s.
Kempshot Observatory west of Lord Rodney's statue - - 4 18-83
Lord Rodney's statue west of Greenwich - - - 5 7 10*65*
Therefore —
h. m. s.
Kempshot Observatory is west of Greenwich - - - 5 11 29*48
The latitude supplied by Mr. Hall is —
18 24 51 N.
Observations of the Contacts of the Sun and Venus.
Mr. M. Hall.
Observed with a 4-inch equatoreal ; power 200, with a first surface reflecting prism,
and a sliding glass shade.
Ingress.
The morning of December 6 was very fine. A little after 7 a.m. the equatoreal was
pointed towards Venus, a low power, the first surface reflecting prism and a very light
glass shade were used, but although a watch was kept until 15 minutes before externa]
contact, yet nothing whatever was seen of the planet.
The low power was then changed for a power of 200, the sliding glass shade was
adjusted to the eye-piece, and the focus was carefully obtained by means of the only
distinct spot there was on the Sun's disc, the mottling of the surface was clearly seen,
and the definition was noted as good. The telescope was then directed towards the
point of contact.
* Keport of tbe Telegraphic Determination of differences of longitude in the West Indies and Central
America by Lieut. Commander F. M. Green, U.S.N.
F 3
40
As the time of external contact approached, a cloud obscured the Sun, and when the
cloud had so far passed away that the Sun was visible, the planet had made a notch in
the limb, as represented in Fig. 1.
The sliding glass prism proved to be most useful, as it was pushed entirely aside for
this observation.
The time noted by the clock corresponded to 20h. 51m. 51'46s., and watching the
increment of the notch, I wrote down that the contact might have occurred 30 seconds
earlier. Again the notch in the Sun's limb was 1'5" according to Fig. 1, and as 15"
corresponds to an interval of 30 seconds, we may assume as the epoch of external
contact 20h. 51m. 2146s. local mean time with a probable error of less than 10
seconds.
When about half the body of the planet was upon the Sun's disc, there were faint
indications of the other half outside the disc, the exterior half was seen projected
against an illuminated background, and as this effect increased towards the Sun's limb,
there is reason to suppose that the exterior half of the planet was seen projected against
the solar corona.
But there was no appearance of any arc of light round the following limb of Venus
until 21h. 4m. 19s. local mean time, or eight minutes before internal contact, when the
light suddenly burst out at the two points where the disc of Venus was cut by the
Sun's limb. From these two points the light spread rapidly outwards, and in about
10 seconds the exterior limb of the planet was completely illumined. This arc of
light was of the same colour and brilliancy as the surface of the Sun near the centre of
the disc, and consequently it was more brilliant than the surface of the Sun near the
limb. When the planet was quite within the Sun's disc, it had a faint edging of light,
but when the planet was at her nearest to the centre of the Sun this edging was
hardly visible.
But still as internal contact approached, the arc of light could not be distinguished
from direct sunlight, and, as there was no " black drop " or distortion of any kind, I
began to fear I should see nothing to mark contact, but at length I saw a few inter-
ference lines, between the limbs of the Sun and planet, the planet being apparently
wholly within the disc of the Sun. These lines were light brown in colour, parallel
to the limbs, from 5" to 10" in length, and very tremulous.
The effect produced by these lines was noted as " shadow " ; they were first seen at
14h. 12m. 56s. by clock. At 14h. 13m. 3s. by clock, they produced quite a strong
shadow. At 14h. 13m. 10s. by clock, they had nearly disappeared, and at
14h. 13m. 28s. by clock there was nothing whatever to be seen of them.
Fig. 2 was drawn to represent the phenomena at 14h. 13m. 3s. when the interference
lines were strong.
We may therefore take the epoch —
14h. 13m. 19s. by clock or 21h. 12m. 21*46s. local mean time ;
as the time of the last appearance of any well-marked and persistent discontinuity in
the illumination of the apparent limb of the Sun near the point of contact, and this
time is subject to a probable error of about four seconds.
A subsequent note was made that about 10 seconds before the shadow was seen, the
planet appeared as in Fig. 2, Plate XIV., Transit of Venus 1874 ; but as the exterior
arc of light was really brighter than in that drawing the phenomena are better repre-
sented by Fig. 3 of this report.
Egress.
As the time of egress approached, the definition became very bad, clouds were con-
tinually passing and there was much " boiling," the sliding glass shade was moved
backwards and forwards continually, and often pushed aside altogether.
Under these circumstances the planet was seen to move up to the Sun's limb without
any " black drop," distortion or interference lines, and at 2h. 36m, 25s. local mean
time, when clouds entirely obscured the Sun, there was only a very narrow thread of
light left, so narrow that I felt apprehensive that contact, as observed at ingress, had
already passed.
The Sun appeared again at 2h. 36m. 48s., when it was seen that the. preceding limb
of Venus had advanced beyond the Sun's limb, as shown in Fig. 3.
If, therefore, we assume that the arc of light was a tangent to the Sun's limb at
2h. 36m. 25s., contact as observed at ingress must have occurred when the limb of the
planet was about 1" further from the limb of the Sun, or 20 seconds earlier. This
gives as the time of internal contact 2h. 36m. 5s. local mean time.
41
Again, the notch seen at 2h. 36m. 48s. at egress appeared as large as the notch seen
at ingress 33 seconds before contact, but the definition at egress was very bad, while
that at ingress was very good, so that the notch must have been really larger at egress,
say 0"*5 ; and this gives as the time of internal contact 2h. 36m. 5s. again. Hence
we shall take as the epoch of internal contact at egress, 2h. 36m. 5s. local mean
time, with a probable error of about five seconds.
Clouds prevented my seeing the exterior arc of light disappear, the arc was then five
minutes after contact.
Clouds prevented me from making a better observation of the external contact than
the following. At 2h. 56m. 16s. local mean time, the notch appeared as large as it did
when first seen at ingress (Fig. 1), but it really must have been a good deal larger, say
1", so that external contact must have occurred about 50 seconds afterwards, or at
2h. 57m. 6s. local mean time, with a probable error of at least 10 seconds.
Collecting the times, we have : —
Ingress.
Clock Time. Local Sidereal Time. Local Mean Time. Greenwich Mean Time.
h. m. s. h. m. s. h. m. s. h. m. s
1. 13 52 46 13 52 52-25 20 51 5146 2 3 2094
2. 14 13 10 14 13 1661 21 12 12-47 2 23 4195
3. 14 13 19 14 13 25-61 21 12 21-46 2 23 50-94
4. 14 13 28 14 13 34-61 21 12 30-45 2 23 5993
Egress.
No actual observation of contact.
Whence the equations —
1. 4-917 = 2-296 8*- -8R -fy +0-514 S« +0-831 SA -0-052 U
2. 3-203 = 2-215 3x -8R +fy +0-467 3a +0-862 3 A -0-050 U
3. 3-643 = 2-215 3tt -3R +fy> +0-467 3a +0-862 8 A —0050 Si
4. 4-083 = 2-215 Stt -dR +8p +0-467 8a +0-862 dA -0-050 U
BERMUDA.— GIBB'S HILL.
S.
h. m.
Longitude of station - 4 19 2045 W. of Greenwich,.
Latitude „ - - 32 14 46-6 N.
Observation of the Contacts of the Sun and Venus.
Mr. J. J. Plummer.
Observed with a Cooke equatoreal of 6 inches aperture, Steinheil positive eye-piece ;
power 177, and clock Dent 2015.
Ingress.
Time of first external contact 14h. 43m. 48 s 0s. by clock, clouds passing at the time,
estimated by further passage upon the limb to be late about 13 seconds. Contact
observed without wedge,* but the faint end of the wedge was immediately brought
into use to estimate the interval by which the time of observed external contact is
too late.
* Subsequently I am not quite sure of this fact, but changes from direct vision to the thin end of wedge had
been frequent during the few minutes that contact was waited for.
F 4
42
At 14k 47m. 20s. the aureole was seen all round Venus, but particularly brilliant
in position a in figure.
At 14h. 51m. 30s. aureole does not seem to become more marked; expect no
difficulty with it. (Later on it was more distinct, and was visible up to the instant
of internal contact.)
h. m. s.
G-eometric contact - - - 15 3 46 by Dent 2015.
a 15 3 59-5
b 15 4 13-5
(Counting one second slow, i.e., the seconds should be 47s., 60*5s., and 145s.
respectively).
The first time is that of geometric contact ; it is believed to be fairly accurate,
that is to say, I do not think it is more than three seconds in error. The other phases
came on quicker than was expected, but are observed to the satisfaction of the
observer. The time marked "a" is that when sunlight was seen between the limbs of
the Sun and planet, or it is the completion of the interval between the cusps by a
grey or colourless haze distinct from (and greatly brighter than) the aureole (which
was not troublesome), and distinct from the perfect and bright sunlight that filled the
interval at the moment marked " &." The only drawback to the satisfactory character
of the observation was that the Sun clouded immediately afterwards, and did not
allow of that distinct verification after the occurrence that could have been wished.
The illumination was carefully kept at the mean brightness by estimation as directed
in the instructions, but the passing clouds rendered frequent changes of the wedge
necessary.
Egress.
h. m. s.
a - - - - 20 27 58-0 by Dent 2015.
b 20 28 14-5
Geometric contact - - - 20 28 290 „
Observed through dense cloud without wedge. Image very faint indeed, and
observation wanting in the certainty obtained at ingress. There was much tremor
of the limbs, both of Yenus and the Sun. The times marked "a" and "6" are
comparable with those marked "6" and "a" at ingress, but the utmost care was
required to make them out; and nothing bat the similar observations in the morning,
which prepared the observer for these changes, would have led to their being seen
at all.
li. m. s.
Second external contact • - 20 48 25*5
This is the last time at which the planet was certainly seen on the disc, being at
this moment nearer the true external contact than at the time marked for first
external contact at ingress. The Sun having been mostly hidden between third and
fourth contacts was &(a brighter at this instant, though boiling greatly. The extreme
thin end of the wedge was used.
I do not look upon this observation* as of any value unless confirmed, and the
illumination was as far removed from the standard as possible, that is to say, the
phenomenon was barely visible.
In further explanation of the phenomena observed at contact of Venus with the
Sun's limb I wish to addf : —
1st. That the average width of the aureole was estimated at 1", and the brighter
portion had an estimated breadth of l"-5. These were obtained with reference to the
wires in the field, whose distance apart is supposed to be about 1".
2nd. That the "black drop" or "ligament" connecting Venus with the region
exterior to the Sun's limb was not at any time as dark as the body of the planet.
3rd. That the appearance of sunlight throughout the whole width between the cusps
was a sudden and marked phenomenon, about which there could be no doubt. The
time noted may be a trifle late (say half a second), as I was determined to be quite
* This remark applies to the internal contact at egress, and equally to the three times marked " a" " b" and
geometric contact ; the circumstances under which these times were noted being similar.
f These remarks are of a general character. They (with the exception of the fifth) refer entirely to
the internal contact at ingress ; the circumstances at egress allowed of no description of the minuter
phenomena.
43
sure of its persistent character. Still, I am not disposed to recommend that any
alteration should be made from the time set down.
4th. Between the times marked " a " and " b " there was a gradual diminution of
intensity of shade on the so-called " black drop," so that it was far from being a
conspicuous phenomenon towards the end of that interval. The time noted is that of
the last moment when it was perceptible to me.
5th. Although much doubt exists with reference to the observations at egress for
reasons already explained, the final or second external contact must be held to have
been well observed, and is accurate to three or four seconds or possibly less. The
ripples along the Sun's limb were seen to break against the dark disc of Venus for
about half a minute before this time, after which they met with no obstacle.
N.B. — These notes were written on the following day. They are not intended to
modify what was written down at the time, but merely to supply omissions and to
call attention to the satisfactory character of the final* contact, which, owing to the
disappointment of partial failure at internal contact, was not estimated at its true
value at the time.
And we therefore get finally for times of contacts —
Ingress.
1. First seen
2. Geometric
contact
3. a
4. b -
Clock Time.
'}
h. m. s.
14 43 480
15 3 47
15
15
4 0-5
4 145
Local Sidereal Time. Local Mean Time.
h. m. s.
14 45 29-95
15
15
5 42-39
5 56-39
h. m. f».
21 44 29-09
15 5 28-89 22 4 24-75
22 4 38-22
22 4 52-18
Greenwich
Mean Time.
h. m. s.
2 3 49-54f
2 23 45-20
2 23 58-67
2 24 12-63
Egress.
Clock Time. Local Sidereal Time. Local Mean Time.
h. m. s.
20 27 58-0
20 28 14-5
5. a
6. 6 -
7. Geometric
contact
8. Last external^ on 48 25-5
contact -J
20 28 29-0
h. m. s.
20 29 39-64
20 29 56-14
20 30 10-64
20 50 7-16
h. m. s.
3 27 42-39
3 27 58-84
3 28 13-30
3 48 6-56
Greenwich
Mean Time.
h. m. s.
7 47 2-84
7 47 19-29
7 47 33-75
8 7 27-01
Whence the equations —
Ingress.
1.
4-984 =
2-455 8t
2.
1-700 =
2-403 8tt
3.
2-371 =
2-402 Stt
4.
3-049 =
2-402 Stt
8R _ 8p +0-507 8a +0-835 8A -0-052 U
§r + 8 p +0-461 8a +0-867 8A -0-049 U
8R + 8 p +0-460 3a +0-867 8A -0-049 U
8R + ty +0-460 Sa +0-867 8A -0-049 U
5.
7-006
6.
7-819
7.
8-541
8.
5-373
Egress.
-2-566 oV + 8B, - 8 P +0-811 8a -0-477 8A
-2-567 8tt + 8R - 8p +0-812 8a -0-476 8A
-2-567 8tt + 8R - 8p +0-812 8a -0-476 8A
-2-593 8tt + SB, + 8p +0-836 8a -0*424 8A
■0-050 8*
-0-050 8£
-0-050 8i
-0-053 U
* The external contact at egress.
22653.
f Estimated by observer to be 13 seconds late.
G
44
Observation of the Contacts of the Sun and Venus.
Lieut. C. B. Neate, R.N.
Observed with 6-inch Naylor equatoreal ; power about 180.
Ingress.
At 2h. 8m. 21s. by chronometer Arnold and Dent 715 I observed a fine light
shading on Yenus' s following limb. I have nothing to remark about this, except that
I estimate that I was three or four seconds late at least.
h. m. s.
(2) 2 28 4 by Arnold and Dent 715.
(3) 2 28 13
(4) C2 28 321
w \2 28 34 J
At time (2) I observed what apparently was geometrical contact. This I considered
difficult to estimate. At time (3) I observed the band between Yenus and the Sun
(never quite as dark as Venus) change colour from dark to a dusky brown. This band
gradually got lighter till time (4), when it trembled, wavered, and disappeared
between 32s. and 34s.
When about half on the following limb of Yenus appeared bright, but not so bright
or the depth of the bright part so great as in 1874.
The first observation was made with the extreme light end of the wedge. All
others were made with the wedge at the place marked ; that is one that I had been
accustomed to use for some days past.
Time (2), as I have before stated, was very difficult to estimate, and I do not
consider it very reliable. Probably between (2) and (3) fleecy clouds crossing the
Sun necessitated my continually adjusting the wedge to the varying conditions of
light, but at (3) the Sun was perfectly clear of clouds.
The band between Yenus and the Sun was at first uniform in colour, but never so
dark as the body of the planet. I watched the band very attentively, and at the time
recorded (3) it changed colour or got decidedly lighter, after which it got gradually
lighter and diminished in breadth. At time (4) the band ceased to exist. The fact
of the limb of Yenus about the point of contact being bright did not disturb me or
in any way interfere with my observation. I am confident the band disappeard at
time (4), and there was uninterrupted sunlight between the limb of the Sun. Almost
immediately after the Sun was almost obscured by clouds. I estimate the depth of
the broadest part of the bright ring or aureole to have been about two in terms of the
breadth between my fine wires.
Note made an hour afterwards —
Three or four seconds might possibly have included the phenomenon (4), but at the
time I was under the impression that two only included it.
Egress.
h. m. s.
(5) 7 52 34 by Arnold and Dent 715.
This time is for an observation of an approximate geometrical contact ; it was
observed without any shade. Large masses of cloud had been passing the Sun for
two or three hours before egress, and the Sun could only be seen through occasional
openings. Through one opening I just caught sight of Yenus on the Sun's limb, and
she appeared to be in geometrical contact ; but I cannot pretend to any great accuracy,
not even within 10 seconds, in this observation.
h. m. s.
(6) ■< g ^ ,q >by Arnold and Dent 715.
At about 8h. 11m. 30s. the Sun shone brighter, and I could see a little bit of Yenus
distinctly ; at 35s. I suspected she had left the Sun's limb, but a cloud passed across ;
at 8b 11m. 40s. I was certain Yenus had gone for good.
The Sun's limb was boiling and very agitated; definition otherwise fairly good.
No aureole seen during egress.
[The fine wires were separated by about a second of arc]
45
And we therefore get for times of contacts —
Ingress.
Chronometer Time.
Local Sidereal Time.
Local Mean Time.
Greenwich Mean Time,
1.
2.
3.
h.
2
2
2
"2
2
m.
8
28
28
28
28
J~2 28 32 \ J
\2 28 34 J \
S.
21
4
13
32"
34
h.
14
15
15
15
15
m.
45
5
5
5
5
36-49
22-66
31-69
50-74
52-74
} (
h.
21
22
22
22
22
m.
44
4
4
4
4
35-61
18-54
27-54
46-54"
48-54
h.
2
2
2
"2
2
m.
3
23
23
24
24
\ J"2 24 6-99 1
j \2 24 8-99/
56-06
38-99
47-99
6-9«'
8-99
Chronometer Time.
Egress.
Local Sidereal Time. Local Mean Time.
m.
5.
6.
h. m.
20 30 44-58
"20 49 48
20 49 53
m.
Greenwich Mean Time,
h. m. s.
f8 11 351 f20 49 48-641 f3 47 48-091 J"8 7 8-541
•\8 11 40 J \20 49 53-66 J 1 3 47 63-09 J 1.8 7 13-54/
3 28 47-15
3 47 48-
3 47 53-
7 48 7-60
'8 7 8-.
8 7 13-
Whence the equations-
1. 5-319 =
2. 1-390 =
3. 1-835 =
4 (mean). 2-828 =
5.
6.
{
10-235 =
4417 =
4-680 =
Ingress.
2-454 oV — 8R - 8p +0-507 8a +0-836 8 A -0-052 U
2-403 8tt - 8R + §p +0-461 8a +0-866 8A -0-049 8*
2-403 8tt - 8R + 8 P +0*461 8a +0-867 8A -0-049 It
2-402 8tt - 8R + 8p +0460 8a +0-867 8A -0-049 8*
Egress.
-2-568 8tt + 8R - 8p +0-813 8a -0474 8A -0-050 U
-2-592 8tt + 8R + 8p +0-835 8a -0425 8A -0-053 It
-2-592 8tt + 8R + 8p +0-835 8a -0425 8A -0*053 8*
UNITED STATES.— CAMBRIDGE, MASS.
The observing station is only a very short distance from the Harvard College
Observatory, and its position determined by direct measurements is —
h. m. s.
Longitude - - 4 44 31*23 W. of Greenwich.
Latitude
42 22 43-3 N.
Observations of the Contacts of the Sun and Venus.
Messrs. J. R. Jewett and E. P. Sawyer.
Observed with a 4-inch refractor of 44 inches focal length, equatoreally mounted ;
power 150. The object-glass was smoked by the maker, Mr. Clacey, for direct
vision, and worked admirably. The times given are Harvard College Observatory
times.
Ingress.
Mr. J. R. Jewett.
The morning of December 6 was very cloudy, and the prospect of success far from
encouraging, but before the first contact the clouds began to break up, and, although
not in time to observe the first contact, the second contact was quite well observed
through a thin stratum of cirrus, this serving to dispel the formation of the " black
drop " phenomenon.
G 2
46
At 21h. 39m. 45s., Harvard College mean time, second contact had taken place,
this representing an apparent true geometrical contact. The interval between the
morning and afternoon contacts was occupied in looking carefully over the whole
disc of the Sun for a satellite, which it is needless to say was not observed, nor
were any spots seen on the disc of the planet, or bright ring of light encircling' the
same.
Egress.
Mr. E. P. Sawyer.
The last) contacts were observed under more favourable conditions than the morning
contacts, notwithstanding a rather strong breeze blowing at the time, and the low
altitude of the Sun. A slight haze, considered rather advantageous than otherwise,
covered the sky in the south-west, and the Sun's limb appeared but slightly undulating'
At 3h. 2m. 31-5s., H.C.M.T., the first "not yet" was recorded, the planet beginning
to approach the Sun's limb, and this was repeated at intervals of a few seconds until
3h. 2m. 59-5s., when the word "past" was given. The moment of true contact was
assumed to have taken place half-way between the last recorded "not yet" at
3h. 2m. 52s. and "past" at 3h. 2m. 59'5s., or at 3h. 2m. 56s., Harvard College mean
time, and considered very good. The last contact was at 3h. 23m. 37s., Harvard
College mean time. The moment of last contact was assumed to have occurred
slightly more than half-way between the last recorded " not yet " at 3h. 23m. 24s.,
and the word " past " recorded at 3h. 23m. 47s. or at 3h. 23m. 37s. No black drop'
or ligament of any kind was observed, nor was Venus observed after leaving the
Sun's disc.
Collecting the times, we have —
Local Sidereal Time.
Ingress.
Harvard College Mean Time. Greenwich Mean Time.*
b. m. s.
1. 14 40 48*98
Local Sidereal Time.
h. m. s.
2. 20 4 53-07
3. 20 25 3747
h. m. s.
21 39 45
Egress.
Harvard College Mean Time,
h. m. s.
3 2 56
3 23 37
11. 111. S.
2 24 15-98
Greenwich Mean Time.*
h.
7
8
m.
47
8
26-98
7-98
Whence the equations —
Ingress.
1. 1-324 = 2-615 fa -8R + Sp 4-0-459 8« +0-868 8A -0-049 U
Egress.
2. 6-761 = - 2-404 fa + 8R - % +0-810 &t -0-480 SA -0-050 U
3. 5-887 = - 2-408 fa + 8R + Sp +0-835 Sa -0-427 8A -0-052 U
CANADA.— KINGSTON OBSERVATORY.
The longitude of the station from two exchanges of signals with the Toronto
Observatory given in Mr. Carpmael's report is —
5h. 5m. 57-27s.f W. of Greenwich.
The latitude supplied by Professor Williamson is—
44 13 25-2 N.
The above positions have only been used for the computation of the factors of parallax.
* Assuming Harvard College 4h. 44m. 30-98s. W. of Greenwich.
t Assuming Toronto Observatory 5h. 17m. 34*7s. W. of Greenwich.
47
Observations of the Contacts of the Sun and Venus.
Professor J. Williamson.
Observed with a 6^-inch equatoreal by Alvan Clark and Sons, solar reflecting prism
and neutral tint glass wedge, positive eye-piece power 120, which was found to give
the sharpest and best defined vision of the limbs of the Sun and planet. The times
of contacts were registered on a chronograph and also noted by chronometer Parkinson
and Frodsham 2382, assisted by Professor Dupuis.
* Ingress.
The weather for a week before the transit had been very unfavourable, and we began
to fear that our preparations would prove fruitless after all, but we were agreeably
disappointed by the 6th of December being, on the whole, a fine day, particularly so
in the afternoon. The early morning sky was overcast, as the time for the commence-
ment of the transit approached, however, it became clearer, and Professor Dupuis
and I repaired to our posts, while Mr. James M. Dupuis was at hand to render very
useful assistance in various ways as it might be necessary. One of the passing clouds
which were beginning to disperse obscured the view of the first external contact, and
the planet was in consequence not seen until it had partly entered on the Sun's disc.
This was at 20h. 45m. 5s. by chronometer.
At 20h. 53m. by chronometer a line of light appeared round the planet on the side
away from the Sun, and apparently brighter towards the southern limb of the planet.
The clouds had now passed away, and the approach to the first internal contact was
noted at 21h. lm. 25s. by chronometer, and by chronograph connected with mean time
clock.
The first internal contact itself, that is, when the limbs of the Sun and planet
appeared just to touch each other, took place, as nearly as could be judged, at
21h. lm. 44s. by chronometer. For a little while after, the limbs seemed slightly to
separate, a dark shade occupied the narrow interval between them, extending a little
way on each side of the former points of apparent contact. The time when this dark
shade began to break away and disappear occurred at 21h. 2m. 40s. by chronometer
or 21h. 19m. 46*25s. by chronograph. This I regard as the true time of internal
contact at ingress. There was still some remaining haziness in the atmosphere, but,
as the sky was bright and free from clouds at the time, both of these contacts were
very distinctly seen. There was nothing of the so-called black drop, but only the
dark shade already referred to.
Egress.
Not long after the last contact at ingress clouds began again to spread over the sky,
and continued to do so till about noon, when they again gradually passed off, and from
12h. 30m. p.m. to the end of the transit, as well as throughout the afternoon and
evening, the heavens were perfectly clear. The first internal contact at egress took
place at 2h. 42m. 53'20s. by chronograph. The dark haze seen at ingress in the
morning began at this time to be again observed at egress, but the interval during
which it continued and discontinuity was noted, was much shorter than in the forenoon,
the last internal contact at egress, that is when the outlines of the limbs appeared
exactly to touch, occurred at 2h. 43m. 12*54s. by chronograph. The former of these
times I consider the true mean time by chronograph of internal contact at egress.
The last external contact took place at 3h. 3m. 43* 15s. by chronograph.
Collecting the times relating to the contacts, we have —
Ingress.
h. m. s. h. m. s.
1. First internal contact 21 1 44* by chronometer
2. DisappearanceofdarkJ 21 g ^ ^ ^ ^ 46 . 25 by chronograp ^
* No chronograph time given for this observation.
a 3
48
Egress.
3. Appearance of dark haze -
4. Outlines of limbs appeared to touch
5. Last external contact
2 42 53-20 by chronograh.
2 43 12-54
3 3 4315
From the telegraphic signals exchanged between Kingston and Toronto Observa-
tories, results of which are given in Mr. CarpmaeFs report of the Canadian observa-
tions of the Transit of Venus, 1882, we get the following corrections of the clock
connected with the chronograph —
h. m. m. s.
December 5 at 11 37*7 by clock. Clock fast of Toronto mean time —12 20*74
6 at 9 49-2 „ „ ■ „ „ -12 22-65.
We therefore get for times of contact^, assuming that first internal contact occurred
exactly 56s. before disappearance of dark shade, as indicated by chronometer times.
Chronometer or
Chronograph Time.
Ingress,
Local Sidereal Time.
Toronto Mean Time.
Greenwich Mean Tin
h. m. s.
1. 21 1 44
2. 21 19 46-25
Chronograph Time.
h. m. s.
14 19 10-29
14 20 6-45
Egress.
Local Sidereal Time.
h. m. s.
21 6 28-67
23 7 24-67
Toronto Mean Time.
h. m. s.
2 24 3-37
2 24 59-37
Greenwich Mean Tir
h. m. s.
3. 2 42 53-20
4. 2 43 12-54
5. 3 3 43-15
h. m. s.
19 44 6-02
19 44 25-41
20 4 59-36
h. m. s.
2 30 31-16
2 30 50-50
2 51 21-08
h. m. s.
7 48 5-86
7 48 25-20
8 8 55-78
Whence the equations-
1. 0-211 =
2. 2-949 =
3. 7-739 =
4. 8-687 =
5. 7-415 =
Ingress.
2-672 8a- - 6R + V +0-460 3a +0-867 8A -0-049 ti
2-671 8x - 8R + 8p +0-458 o« +0-868 8A -0-049 U
-2-295 8x +
-2-295 §tt +
-2-301 8tt +
Egress.
8R _ 8 p +0-810 8a -0-480 8 A -0-050 U
8R - o> +0-810 8a -0-479 8A -0-050 U
8R + 8p +0-835 8a -0-426 8A -0'052 U.
CANADA.— OTTAWA.
The temporary observatory was erected on Nepean Point.
The longitude of the station from two exchanges of signals with the Toronto
Observatory extracted from Mr. Carpmael's report is —
h. m. s.
Ottawa (Nepean Point) east of Toronto Observatory - - 14 47*2
Toronto Observatory west of Greenwich - - - - 5 17 34-7
or —
Ottawa (Nepean Point) west of Greenwich - - - 5 2 47-5
The approximate latitude is —
45 26 N.
The above positions have only been used for the computation of the parallax
factors.
* The longitude of the Toronto Observatory supplied by Mr. Carpmael is 5h. 17m. 34 -7s. W. of Greenwich.
49
Observations of the Contacts of the Sun and Venus.
Mr. F. L. Blake.
Observed with a 4-inch achromatic telescope, altazimuth mounting. The definition
of the telescope is noted as very fine, no information of power used is given. Times
noted by Mr. B. C. Webber with chronometer Frodsham 1752.
Ingress.
The morning of the 6th broke with dense clouds at low elevation with no immediate
prospect of breaking. Soon after eight o'clock signs of clouds dispersing in S.B.
At 8h. 15m. by chronometer Sun shone out brilliantly. Sighted on the Sun and
focussed on Sun spots, at 8h. 24m. rice grains on Sun just discernible.
At first external contact atmosphere rather hazy. Time of first external contact
8h. 34m. 45s. by chronometer. This time is not to be depended on as my attention
was called away just at moment of contact and had to estimate, the notch being formed
on the Sun when I again put my eye to the telescope. I do not think it can be more
than five or six seconds out at most.
At no time could I detect any portion of the planet that was off the Sun. The
portion on the Sun was very black. Towards internal contact clouds began to pass
over the Sun, hiding it completely at times. Just before internal contact caught a
glimpse of the Sun through a break in the clouds which lasted long enough to catch
the contact. No black drop observed. Bright cusps of the Sun met at 8h. 54m. 51s.
by chronometer. The Sun became obscured at 8h. 55m. 8s. by chronometer, during
which interval of 17 seconds the band of light between the limbs of Venus and the Sun
broadened considerably. The time 8h. 54m. 51s. was the last time of appearance of
discontinuity in the illumination of the apparent limb of the Sun. Sun reappeared at
9h. 11m, with prospects of a fine afternoon. For an hour, with the exception of the
time occupied in the passage of a few fleecy clouds over the Sun, the planet was
observed. No markings of any kind could be distinguished on its surface which
appeared intensely black in comparison with the bright face of the Sun. Clouds again
gathered thickly, and snow began to fall.
Egress.
Snowstorm continued without intermission up till 2h. 5m., when clouds began to
clear off in the south-west, and the Sun began to peep out, when Venus was observed
approaching internal contact at egress, being then about half its own diameter from
limb of Sun. Mr. Webber began to count at 2h. 16m. At 2h. 17m. 19s. by chrono-
meter, slight fading was observed near point of contact which gradually increased until
2h. 18m. Os. by chronometer, when contact was observed by first appearance of
blackness like that of the planet, and the bright cusps began to recede.
No black drop or distortion of the limb of Venus was observed although the edge of
the Sun was boiling just a little.
I used an illumination about midway between total darkness and brightness that the
eye could just bear.
When the planet was half way off the Sun, I thought I could faintly discern the
limb off the Sun, but could not be sure of it. Between internal and external contacts
nothing unusual was observed. At 2h. 38m. 12s. by chronometer the dark body of the
planet left the Sun, although a faint shading of the limb of the Sun near point of
contact till 2h. 38m. 31s. was observed; nothing unusual in the illumination of the limb
of the Sun was observed after that time. For about an hour after external contact at
egress the Sun shone brilliantly, when clouds again arose, and the Sun was shrouded
from sight for the rest of the day.
Collecting the times relating to the contacts, we have
Ingress.
1.
9
n . h. m. s.
First external contact - - - 20 34 45 by chronometer
Last appearance of discontinuity, &c. - 20 54 51
G 4
50
Egress.
3. Slight fading near point of contact
4. Contact -
5. Dark body of Venus left the Sun
6. Faint shading of Sun's limb till
h.
m.
s.
2
17
19 by chronometer.
2
18
o
2
38
12
2
38
31
We therefore get for times of contacts-
Ingress.
Chronometer Time.
Local Sidereal Time.
Toronto Mean Time.
Greenwich Mean Time.*
h. m. s.
1. 20 34 45
2. 20 54 41
Chronometer Time.
h. m. s. h. m. s.
14 2 59-60 20 47 1137
14 23 8-96 21 7 17'43
Egress.
Local Sidereal Time. Toronto Mean Time.
h. m. s.
2 4 46-07
2 24 52-13
Greenwich Mean Time.*
h. m. s.
3. 2 17 19
4. 2 18
5. 2 38 12
6. 2 38 31
h. m. s.
19 46 30-90
19 47 12-03
20 7 27-40
20 7 46-46
h. m. s.
2 29 46-40
2 30 27-41
2 50 39-46
2 50 58-47
h. m. s.
7 47 2110
7 48 211
8 8 14-16
8 8 33-17
"Whence the equations-
1.
2.
5-747 =
2-557 =
3. 5-533 =
4. 7-556 =
5. 5-226 =
6. 6-226 =
2-697 8x
2-675 oV
-2-297 8:r
-2-297 3tt
-2-297 8tt
-2-297 ov
Ingress.
£R — 8p 4-0-504 8« +0-837 8A
8R 4-gp +0-458 8a +0-868 8A
Egress.
+ 8R
+ 8R
+ 8R
+ 8R
-8 P
-Sp
+ 8 P
+ o P
+0-809 8a
+0-810 8a
+0-834 8a
+0-835 8a
-0-482 8 A
-0-480 8A
- 0-428 8A
-0-427 8A
• 0-052 8*
•0-049 U
-0-050 8£
• 0-050 U
-0-052 8*
• 0-052 U
CANADA.— COBOURG.
The approximate position of the observing station taken from United States charts
of Lake Ontario is —
h. m. s.
Longitude - - 5 12 37'5 W. of Greenwich.
Latitude - - - 43 57 N.
These positions have only been used for the computation of the parallax factors.
Observations of the Contacts of the Sun and Venus.
Professor A. R. Bain.
Observed with a 4 1 -inch refractor by Smith, Beck and Beck, London ; equatoreally
mounted ; power about 150. Mr. Bain was assisted by Drs. Haanel and Coleman, the
latter gentleman took the times from the chronometer.
Egress.
The sky in the early part of the morning of December 6 was clear enough to justify
the most sanguine expectations of getting good observations of at least the first
contacts, but a few minutes before 8 a.m., dense masses of cloud began to rise in the
* The longitude of the Toronto Observatory supplied by Mr. Carpmael is 5h. 17m. 34 - 7s. W. of Greenwich.
51
north-west, and by 10 minutes past 8 the whole heavens, with the exception of a
small area in the north-east and east, were covered, competely shutting out the Sun
from view. These clouds did not break away until long after external and internal
contact at ingress had passed.
About lOh. 30m. a.m. rifts in the clouds appeared, and shortly before 11 a clear
view of the planet on the Sun's disc was obtained. The disc of the planet, especially
towards its circumference, presented a purplish hue, while the centre had a faint light
spot slightly tinged with a pale slaty green.
Shortly before 2 the atmosphere which had been comparatively steady began to be
disturbed, and rapidly became worse, while flying clouds now and again swept across the
face of the Sun. Before the time of internal contact at egress, the boiling of the
atmosphere was such as to render observations very unsatisfactory.
The limbs of the Sun and planet appeared to spin. The limb of the Sun at which
contact was about to take place seemed to consist of filaments of light, each revolving
swiftly in a small spiral.
Internal contact at egress appeared to take place at 2h. 33m. 27s. by chronometer,
Just at this critical moment a cloud swept Sun and planet out of sight, and when it had
passed a small arc of the planet's limb was decidedly beyond the Sun's limb, while a
narrow beautifully distinct white line of light surrounded that portion of the planet's
limb which was beyond the Sun. When about half the planet's disc had crossed the
Sun's limb, the line of light was decidedly broader on the north-western portion than
it was along the remaining arc. Very soon after clouds hid the Sun from sight and
prevented any observation being taken of the external contact at egress.
Professor Bain further says in a letter dated 1883, January 25 —
" I have the honour to acknowledge the receipt of your note of January 20th, in
which you ask for a further description of phenomena seen at the instant of time at
which 1 had marked down the words " Ap. Contact.' "
In the report already sent I refer to the atmospheric disturbance which grew worse
and worse till all vision of Sun and planet was lost under the flying clouds.
The ever narrowing band of light over which the planet was slowly moving as it
approached the Sun's limb was heaving, boiling, and apparently spinning in a manner
described in previous report, other than this, nothing peculiar was seen. No black
drop presented itself. No distortion of the planet's limb such as an elongation towards
point of contact, nor till after part of the planet was beyond the Sun's disc did any
arc of white light surround any part of the planet's disc. The exact instant when that
beautiful bright white arc of light first appeared I know not, for just after what seemed
to be contact a cloud came over, and when it was passed the arc of light was there.
The cloud was on the face of planet and Sun fully five seconds.
It was impossible to take a point north and another south of the point at which
contact was about to take place, and note when the illumination of the point of contact
began to be distinctly less than that of the points chosen, for the Sun's limb was not
still enough to admit of any such thing. It appeared constantly to heave and surge.
"With this exception the planet moved steadily towards contact, presenting no
phenomena different from those observed at any earlier stage. The various times
correspond simply to remarks made at the telescope, while the observation was making,
the exact words used, and the instant at which each phase was spoken, being noted by
the assistants.
This plan was adopted thinking that if any marked phenomenon presented itself
near time of contact, before or after, the exact second of time when observed could
thus be noted, but nothing in addition to the phenomena already described was seen.
In giving you the colours of the disc of planet I described exactly as seen in our
telescope, of course the purplish hue of the edge would at once inform you that our
glasses are somewhat over corrected.
I forget to mention that during the day the Sun's surface was mottled, but presented
no well marked rice grains, no interlacing willow pattern.
Again Professor Bain says on February 21st, 1883 —
" Dr. Coleman put ' ap. ' down in the hurry, but ' approaching ' was the word used."
The times given for the preceding notes are —
h. in. s.
Atmosphere very unsteady - - 2 32 44 by chronometer.
Approaching contact - - 2 33 5 „
Now - - - - - 2 33 27
Cloud - - - - 2 33 33
Passed - - - - - 2 33 38
a 22653. H
52
The time given for contact in Professor Bain's report is —
h. m. s.
2 33 27 by chronometer,
corresponding to the " Now" given above.
The chronometer correction at time of contact given by Mr. Carpmael is —
m. s.
Chronometer fast of Toronto mean time - - - 2 28*53
We therefore get for time of contact —
Chronometer Time. Local Sidereal Time. Toronto Mean Time. Greenwich Mean Time.
h. m. s. h. m. 8. h. in. s. h. m. s.
2 33 27 19 37 53-18 2 30 58-47 7 48 33-17
Whence the equation —
8-833 == - 2-264 Sv + 3R - 3p + 0-811 U - 0-479 8A - 0-050 U
CANADA.— WINNIPEG.
h. m. s.
Longitude of station - - 6 28 29- 67 W. of Greenwich.
Latitude „ - - 49 55 N.
Observations of the Contacts of the Sun and Venus.
Professor C. H. McLeod.
Observed with a 4- inch refracting altazimuth telescope, a first surface reflecting
prism, a neutral tint wedge, and an Airy eye-piece; power 160. Prof. McLeod
remarks that the mounting of the instrument was very steady. The disc of a bright
star out of focus is round, but with a somewhat jaggy edge. There is the usual
change of colours as the eye-piece is pulled out, viz., from greenish to a green centre
bordered with purple, and beyond the focus a purple centre bordered by green,
changing, as it is pulled still further out, to a uniformly light purple disc. On a night
of not very good definition and full moonlight, <r Cassiopeiae was easily seen double.
The " rice grains " on the day of the transit were just visible with the thin end of the
wedge. The rice grains are generally easily visible. The times were noted by
chronometer Murray 652 by Mr. Payne.
Egress.
On the morning of December 6, the Sun was obscured by cloud and snow drift until
after 9 o'clock. When the Sun had risen above the cloud and snow banks it remained
visible until it had again sunk behind them in the afternoon. The temperature was
18° below zero (Fah.), and the velocity of the wind was 24 miles per hour.
On reaching the station shortly before 11 a.m., and directing the telescope on the
Sun, it was found to shake so violently as to make it impossible to keep the Sun in
view. We immediately set to work to screen the telescope from the wind. After
moving it back so that it stood entirely within the shelter, we covered the roof opening
with the exception of a hole about 1 foot square, through which the Sun could be
seen for some time before and after the contacts at egress. The telescope was then
found to be perfectly steady. All arrangements were completed, and the telescope
directed on the Sun shortly before 1 o'clock, from which time until after the third
contact Venus was kept in view, principally by Mr. Payne, as I wished to rest my eyes
as much as possible before making the observations.
Shortly after lh. 19m. p.m., Mr. Payne began counting seconds. The following is
an exact copy of the record —
li. in. s.
Light about to be broken - - 1 21 55 by chronometer.
Blackness all the way across a second
or two before this - - - 1 22 11 „
Last appearance of gap, approximate - 1 42 13 „
53
Rice grains just visible at internal contact. Illumination poor. Extreme thin end
of wedge used, giving too dark a field, but Sun very much too bright to be observed
without the wedge. This applies more particularly to the last contact ; at times near
the internal contact the illumination was nearly as bright as I desired ; but, con-
sidering the observation as a whole, the field was too dark. I should say the time of
actual internal contact, — "the first appearance of any well-marked and persistent
discontinuity in the illumination of the Sun near the point of contact," — was con-
siderably nearer the first time lh. 21m. 55s. than the second time lh. 22m. lis. The
time I would wish to be taken as the moment of contact as above defined is lh. 22m. Os.
by chronometer.
At lh. 42m. 13s. (by chronometer) there was the slightest possible appearance of a
gap in the limb of the Sun. Just then the illumination became very bad, and my eye
being rather tired, I lost sight of the point of contact.
I have preferred to give my notes as made during the progress of the observations,
and immediately after it, rather than what might, perhaps, better express my meaning,
written at this time. I desire, however, to make the following addition to these
notes.
Definition was fairly good, there being little or no boiling of the Sun's limb. My
remarks as to illumination were written immediately after the last contact, and were
made with the then conditions of the atmosphere in my mind, and were undoubtedly
intended to refer to that time only. These remarks are, however, correctly qualified
in what follows them. The important point is that at internal contact the seeing was
sufficiently good to leave no doubt whatever as to what I saw. There was no " black
drop," but merely a haze, which gradually increased to complete blackness. There
was no haze at lh. 21m. 55s. by chronometer, but it was the last instant at which I
could definitely say there was no appearance of haze. I waited rather too long before
giving the second signal at lh. 22m. lis., and for this reason made the note attached
thereto. The time I have indicated as what I would desire to be taken as the time of
internal contact must be very near the truth.
I stopped observing at lh. 24m., and did not recommence until lh. 39m.
The word " approximate" following the remark opposite to lh. 42m. 13s„ does not
express what was intended. At that time the gap was seen, but it was not seen after-
wards. Had I continued to see it I do not think that any appearance of " gap " would
have been visible for more than five seconds after the recorded time.
After both internal and external contacts, I verified Mr. Payne's counting by looking
at the chronometer and his record.
Collecting the times, we have —
h. m. s.
1. Internal contact - - - 1 22 by chronometer.
2. Last appearance of gap - 1 42 13
We therefore have —
Egress.
Chronometer Time. Local Sidereal Time. Local Mean Time. Greenwich Mean Time.
m. s.
n - m - s- h. m. s. h. m. s. h
1. 1 22 18 22 56-88 1 20 59-23 7 49 2S-&,
2. 1 42 13 18 43 1324 1 41 1227 8 9 41-9*
Whence the equations : —
1. 7-679 = - 1-823 8;r + 8R - ty +0-810 3a -0-480 8A ~0C5i«
2. 5-631 = - 1-826 oY + 8R + 8 p +0-834 8a -0-428 8A —0-053 8*
H 2
54
NEW ZEALAND.— BIDWILL'S.
h. m. s.
Longitude of the station - 11 41 41*47 B. of Greenwich.
O / //
Latitude „ - 41 11 29 S.
Observations of the Contacts of the Sun and Venus.
Mr. J. H. A. Marchant.
Observed with a 4-inch refractor by Browning, kindly lent by Mr. David Gray, of
Wellington ; focal length, 5 feet 6 inches ; power about 200 ; first surface reflecting
prism and neutral tint glass wedge. The motion in altitude and azimuth is effected by
hand rods and slow motion screws. Seconds of chronometer Barraud 2432 called
aloud by Mr. Gr. Struthers. Mr. Wright supervised the calling, booked each minute,
and noted down times and remarks.
Egress.
h. m. 8.
1. Suspicion of haze - - 12 41 57 by chronometer.
2. Haze undoubtedly - - - 12 42 14
3. Contact without doubt - - 12 42 25
The limb of Sun was sharply defined ; limb of Venus not so well, as she appeared
to be surrounded by a haze. No "boiling" appearance about Sun's rim.
The time, 12h. 42m. 14s., was the instant at which the "haze " was unmistakably
visible between the limbs of Venus and the Sun; and the time, 12h. 42m 25s., was the
instant at which the " haze " became black in the centre near the points of contact.
Shortly afterwards the rim of the Sun appeared to advance before the outward limb
of Venus, that is to say, it appeared to be pushed out by the black disc of the planet,
and the aureole was distinctly visible round the outward rim of Venus.
ll. 111. s.
4. Cessation of indentation of Sun's
limb outward, contact at egress - 13 1 50 by chronometer.
After this time no trace of the planet was to be seen.
Definition good. Sun spots and mottled appearance of surface were seen very
distinctly before and after egress ; in fact, the definition was exceptionally good.
Collecting the times, we have —
Egress.
Chronometer Time.
Local Sid
ereal Time.
Mount Cook Mean Time. Greenwich Mean Tin
h . m. s.
h. in.
s.
h. in. s. h. m. s.
1. 12 41 57
12 44
45-06
19 40 9-94 8 1 4-03
2. 12 42 14
12 45
2-05
19 40 26-88 8 1 20-97
3. 12 42 25
12 45
13-05
19 40 37-85 8 1 31-94
4. 13 1 50
13 4
38-02
19 59 59-64 8 20 53-73
Whence the equations-
1. 7-078 =
= 2-214 8?r
+ 8R -
% 4-0-833 8a -0-430 8A -0-053 &
2. 7-964 =
= 2-212 8*-
+ 8R -
8p +0-833 8a -0-430 8A -0-053 8*
3. 8-535 =
= 2-211 8x
-MR -
■8p +0-833 8« -0-430 8A -0-053 U
4. 6-645 =
= 2-083 Stt
+ 8R +
8p +0-853 8« -0-383 8A -0-055 8*
55
Observations of the Contacts of the Sun and Venus.
Captain J. D. Hewitt.
Observed with an 8^-inch Browning reflector.
Egress. — External Contact.
From the "Report on the Surveys of New Zealand, 1882-83," the time of external
contact is given at 13h. lm. 54s., Mount Cook sidereal time. No further information
has been received. This gives —
Egress. — External Contact.
Local Sidereal Time. Mount Cook Mean Time, Greenwich Mean Time.
b. in. s. h. m. s. h. m. s.
1. 13 4 29-56 19 59 51*20 8 20 45*29
Whence the equation —
1. 6-174 = 2-083 &r +8R + 3p +0-853 8a -0-383 3 A — 0-055 S*
NEW ZEALAND.— MOUNT COOK OBSERVATORY, WELLINGTON.
The longitude of the observatory, obtained by exchange of telegraphic signals with
the Sydney Observatory, is —
h. in. s.
Mount Cook Observatory east of Sydney
Observatory - - - 1 34 16-98
Sydney Observatory east of Greenwich - 10 4 48*93
Therefore —
ll. m. s.
Mount Cook Observatory east of Greenwich - 11 39 5*91
The latitude is —
41 18 0-6 S.
Observations of the Contacts of the Sun and Venus.
Mr. C. W. Adams.
Observed with 4|-inch telescope by S. and B. Solomons, of 5-feet focal length,
kindly lent by Mr. H. Barnard, of Taranaki Street, Wellington. It was mounted on
an ordinary stand, and required to be moved by hand ; power 71, the highest power
available, was used. No first surface reflecting prism could be obtained in time, nor
a graduated glass wedge, so the image of the Sun was thrown on a screen. The
screen was 21*9 inches from the eye-piece, and the Sun's image was larger than the
field of view ; but if the whole of the Sun's image could have been seen at once, it
would have been 14*8 inches in diameter. The telescope was set up just outside the
observatory door. The times were noted by the sidereal clock, Mr. W. Holmes
counting seconds in an audible voice, and Mrs. Adams noted down the times and
remarks.
Egress.
About 6 a.m. the edges of the discs of Venus and the Sun appeared very tremulous
and " boiling," but as the time of contact approached the definition became much
more sharp and distinct.
I have very little to record besides the times of actual contact, as there was an
almost entire absence of the incidental phenomena that I had been led to expect.
H 3
56
I kept watching for the hazy or cloudy appearance which I expected would present
itself before internal contact, and fancied I saw a very slight darkening at the edge
of the Suns limb at 12h. 41m. 50s. by clock. The internal contact I noted at
12h. 42m. 10s. by clock ; it was a pure geometrical contact, neither blur nor distortion
being visible.
I noticed no other phenomena between internal and external contact.
External contact I noted at 13h. 2m. 6s. by clock.
The opinion I formed immediately after the transit was that the error of my
observations could not exceed a limit of two or three seconds at internal and five or
six seconds at external contact.
The sky was beautifully clear and the weather calm.
Collecting the times given, we have —
1. Suspicion of slight darkening
2. Internal contact
3. External contact -
We therefore get —
Egress.
Local Sidereal Time. Local Mean Time. Greenwich Mean Time.
tl.
12
m.
41
s.
50 bv clock.
12
42
10
13
2
6 „
fe. m. s. h. m. s. h. m. s.
1. 12 42 1-57 19 40 2-03 8 56-12
2. 12 42 21-57 19 40 21-98 8 1 16-07
3. 13 2 17-53 20 14-67 8 21 8-76
Whence the equations : —
1. 6 : 560 == 2-225 oV 4- m - 8p +0-833 U -0-430 3A -0-052 U
2. 7-603 = 2-225 8x + SR - 8p 4-0-833 U -0-430 3A -0-052 U
3. 7-353 = 2-095 be' + 8R 4- 8p +0-853 la -0-382 SA -0-055 M
These observations have not been included in the final equation, as the method of
observation was entirely different from the rest.
NEW ZEALAND.— BOULGOTT STREET, WELLINGTON.
The longitude of the station is given as 0*34s. W. of Mount Cook Observatory ; it
is therefore —
h. m. s.
11 39 557 E. of Greenwich.
The latitude supplied by the Surveyor-General of New Zealand is —
41 17 143 S.
Observations of the Contacts of the Sun and Venus.
Mr. J. McKerrow.
Observed with a 5-inch Grubb equatoreal belonging to Mr. King, who kindly lent
it and the use of his observatory for the transit ; power used, 250. Neutral tint, dark
glass, and a first surface reflecting prism. A compensated neutral-tint wedge was
available, but Mr. McKerrow preferred the dark glass, as through it there was no
unsteadiness whatever. With the object of diminishing any tremor which might arise
from the reflection of the Sun's rays from the dome and walls of the observatory, these
were painted, a few days prior to the observation, with paint of a neutral tint, and
during the observation were covered with white calico. The times were noted by
sidereal clock. Messrs. Alexander Barron and Thomas Grant, officers of the Survey
Department, assisted in the taking of time and the record of observations.
57
Egress.
The observation of the Transit of Venus at Mr. King's Observatory, Boulcott Street,
by me was most satisfactory, inasmuch as there was no boiling or tremor of the Sun's
limb, nor was there any rim of light or other phenomena around the limb of Venus.
The limbs of both Sun and planet were sharp and distinct, and as they approached
each other the instant when the Sun's limb was disturbed, and rendered obscure by a
rapidly thickening haze or mistiness, was also very well marked, and was noted to the
nearest second. The geometrical contact of the two limbs, that is to say, when the
two appeared to touch each other, was very distinct, there being no drop or pear-
shaped appearance of the planet. With these two phases the observation was com-
pleted ; but, as a rough check on these observations, a third time was noted when
the two limbs had overlapped, forming a ligature or band, which in reality was the
distance between the cusps of Venus as figured on the limb of the Sun.
The time of external contact was not marked by any phenomena other than the
gradual approach of the cusps of Venus as the planet retired from the Sun. Although
the circumstances of this observation as to steadiness and definition were most,
favourable, the time noted is probably uncertain to two seconds, but not more. In
conclusion I have to add that in the absence of clouds, wind, or other disturbing cause
of weather, I cannot conceive of more favourable conditions for the observation.
The times are —
h. m. s.
1. Disturbance of Sun's limb by dark haze - 12 42 3 by clock.
2. Contact complete, the two limbs being
geometrically united -
3. Ligature formed by limbs overlapping
4. Cusps met, Venus off the Sun
Egress.
Mount Cook Mean Time. Greenwich Mean Time.
12
42
12
12
42
18
13
2
6
We therefore get —
Local Sidereal Time.
1.
2.
3.
h.
12
12
12
m.
42
42
42
13-02
22-02
28-02
h.
m.
s.
19
40
13-79
19
40
22-76
19
40
28-75
20
13-40
h.
m.
S.
8
i
7-88
8
i
16-85
8
i
22-84
8
21
7-49
4. 13 2 15-92
Whence the equations —
1. 7-169 = 2-225 8*- 4- 8R - fy +0-833 3« -0-430 8A -0-052 it
2. 7-646 = 2-225 8*- + 8R - 8p 4-0-833 8a -0-430 8A -0-052 it
3. 7-965 = 2-225 orr + 8R - ip +0-833 8a -0-430 8A —0-052 8*
4. 7-282 = 2-095 8x + 8R + ip +0-853 8a -0-382 SA —0-055 it
NEW ZEALAND.— CHRISTCHURCH.
h. m. s.
Longitude of the station - - 11 30 30*94 E. of Greenwich.
Latitude „ „ - 43 31 40 S.
Observations of the Contacts of the Sun and Venus.
Mr. W. Kitson.
Observed with a 6-inch Cooke equatoreal, kindly lent by Mr. J. Townsend, together
with the use of his observatory ; power used, 173. First surface reflecting prism and
compensated neutral-tint glass wedge placed between the eye and eye-lens.
H 4
58
Egress.
During the whole of the observation a light slightly-streaky cirrus cloud was
apparent over the whole of the sky.
At about 6.55 a.m., when the planet was observed, no halo nor any light at all
different from the light of the Sun was visible round the planet, nor was there any
shadow round the planet's limb. The face of the Sun presented a disc of one uniform
and continuous light, the only dark spot being the planet itself.
The planet itself appeared to have a lighter tinge towards its limb. This light
tinge began to displace the blackness of the centre at about one-tenth of the planet's
diameter from the edge. This tinge was of a bluish colour, the centre being almost
black.
From this spot the light tinge extended outwards continuously to the edge of the
planet. I could not detect the appearance of rice grains on the face of the Sun at
any time.*
The first time, 7h. 31m. 2'5s., corresponds to the first appearance to me of a shadow
or darkening of the Sun's face between the limbs of the planet and Sun near the
point of contact.
There was no black drop as I understood black drop, i.e., no absolute apparent
meeting of the two limbs, nor was there any thrusting out of the Sun's limb by the
planet, as I understood was probable.
The second phenomenon, 7h. 31m. 24*5s., occurred when the light between the
planet and the Sun's limb was distinctly obscured, the phenomenon differing from a
haze.
This moment was also estimated mentally by the production of the two limbs of
the Sun and planet, where they were unaffected to the point of contact. I estimated
this time to be the geometric contact. During the last few seconds of observation the
whole effect was rather hazy, probably owing to a cloud intervening.
After first contact at egress the portion of the planet off the Sun was wholly
invisible to me.
Phenomenon corresponding to time 7h. 50m. 53*5s. During the final contact or
separation of the limbs the definition was excellent, much more perfect than at first
contact.
Collecting the times—
1j. m. s.
1. First shadow - - - 7 31 2*5 by chronometer.
2. Internal contact - - - 7 31 24*5
3. Final separation - - - 7 50 53*5 „
We have therefore —
Egress.
Chronometer Time. Local Sidereal Time. Buruham Mean Time. Oreenwich Mean Time.
h. in. s. h. m. s. h. m. s. h. m. 8.
1. 7 31 25 12 33 3070 19 30 13-09 8 1 0-21
2. 7 31 24-5 12 33 52*76 19 30 35-09 8 1 22-21
3. 7 50 535 12 53 24-89 19 50 4-02 8 20 5114
Whence the equations —
1. 6-589 = 2-248 dV + SK - Sp +0-833 oa -0-430 oA -0*052 It
2. 7-741 = 2-245 &r + 8R - 8p +0-834 U -0-429 8A -0-052 U
3. 6-173 = 2-120 8tt + m + 8p +0-853 Sa -0-382 8A -0055 U
Observations of the Contacts of the Sun and Venus.
Mr. J. Townsend.
Observed with a 3f-ineh Dallmeyer equatoreal.
Times taken by a watch showing seconds, which was compared with the chronometer
used by Mr. Kitson shortly before and immediately after the transit.
* Colonel Tupman remarks : — " Mr. Kitson tells me that he cannot see the solar granulations with any
" instrument, and it was certainly through no defect of the instrument that he was unable to see them. 1
" frequently turned it on the Sun and also on stars, and found its defining powers excellent. The compensated
" wedge fitted to the eye-piece was brought from England as a spare one for the Pembroke equatoreal. Every -
" thing connected with the instrument was Cooke's best work."
59
Egress.
Saw Venus on Sun's disc shortly after sunrise. Light cirrus clouds hanging about,
but generally bright and fine weather.
1.
First shadow at contact - - 19
31
13 by chronometer,
2.
Contact complete - - - 19
31
28
3.
Venus left Sun's limb (at 10s. not
seen) - - - - 19
51
9
Part of outline of Venus seen till 12 minutes after internal contact, outside limb of
Sun. Centre of planet when on the Sun quite black, margin for one-third diameter
indigo. At last moment of internal contact light line on advancing limb of planet,
which became very obvious on separation from Sun. No markings or light seen on
body of Venus.
Egress.
Chronometer Time.
Local Sidereal Time. Burnham Mean Time. Greenwich Mean Time.
h. m. s.
1. 19 31 13
2. 19 31 28
3. 19 51 9
h. m. s. h. m. s. h. m. s.
12 33 46-04 19 30 28-39 8 1 15-51
12 34 1-08 19 30 43-39 8 1 30-51
12 53 45-24 19 50 24-32 8 21 11-44
lence the equations-
1. 7-387 =
2. 8-165 =
3. 7-288 =
2-246 3*- 4- 8R - 8p +0-834 8a -0-429 8A -0-052 U
2-244 8*- + 8K - 8p +0-834 8a -0-429 8A -0-052 U
2-117 &r + 8R + fy +0-853 8a -0-381 8A -0-055 (it
NEW ZEALAND.— BURNHAM.
Longitude of station
Latitude „
h. in. s.
11 29 12-88 E. of Greenwich.
43 36 48-1 S.
Observations of the Contacts of the Sun and Venus.
Lieut.-Col. Tupman.
Observed with a 6^-inch Cooke equatoreal ; power 210. A first surface reflecting
Herschelian prism, a compensated wedge of neutral tint inclining to blue, being
attached to the eye-piece between the eye-lens and the eye. Chronometer F. was used
for times.
Egress.
The early morning of December 7 was fine with but little cloud, and scarcely a
breath of wind. I had the roofs and eastern sides of the telescope huts entirely
removed, so that the telescopes were practically in the open air, a great advantage,
especially for solar observations.
By 6 o'clock all was in readiness, and everyone at his post. Every part of both
telescopes was clean and in good order, and the driving clocks ran true. I was
assisted by my wife, who counted aloud the seconds from the chronometer, and by
Mr. Grill, of the Telegraph Department, Wellington, who wrote for me, and called
each minute. The chronometer was so placed that I could see its face. Bombardier
Wilson also assisted in the hut.
At 18h. 25m. Burnham Mean Time, December 6, I examined the Sun with a power of
150, an ordinary negative eye-piece, fitted as described. The planet was as black as
ink, the outstanding blue of the object glass conspicuous along the limb on the black
a 22653. I
60
disc. The granulations of the Sun's surface were remarkably distinct ;; there was
scarcely any boiling, and no cloud over the Sun.
Carefully examining the edge of the planet, I could distinguish no trace of her
atmosphere. The limb was absolutely sharp, of striking abruptness. There was no
trace of any shadow on the Sun's surface without the planet, or of any light within
the planet's disc. I assured myself of this repeatedly during the hour or more that I
had little else to do. The granulations of the Sun's surface, the " rice grains " and
the tiny "pores" were everywhere visible close up to the limb of Venus. She passed
over a more disturbed portion of the photosphere when the solar markings were seen
in actual contact with the limb of the planet.
At 18h. 37m. I inserted the Airy double-image micrometer, which was nicely
adjusted, and took measures of the double diameter of ^Venus.
At 18h. 50m. I tried power 210 with good effect. There was so little disturbance
of the air that a still higher power might have been employed. The solar granulations
were still seen close up to the limb of the planet.
Venus being about her own diameter from the Sun's limb, I replaced the micrometer,
and made measures of the distance of near limbs.
A white hazy cloud had for some time been spreading over the Sun depriving the
planet's disc of the inky blackness before noticed, but there was scarcely any
boiling.
At 19h. 25m. haze over the Sun, vision becoming indistinct.
At 19h. 28m. I no longer saw the granulations. Image steady ; very little boiling.
Venus' disc very sharply defined.
At 19h. 28m. 30s. my wife began to count aloud the seconds. Venus drew pretty
quickly up to the Sun's limb. I expected to see the shadow between the limbs sooner
than I actually did. The distance became very small without any diminution of the
Sun's light, certainly to within one second of arc. A faint shadow grew slowly
between the limbs. At 19h. 30m. 7s. by chronometer I began to suspect it ; at
19h. 30m. lis. I was sure of it. A short ill-defined shadow, not many seconds long,
in the direction parallel to the limbs ; undoubtedly difficult to see, which might have
been due to the haze over the Sun.
At 19h. 30m. 20s. by chronometer the Sun's limb had lost its sharpness from the
overlapping of Venus' atmosphere, and at 19h. 30m. 27s. the atmosphere was con-
spicuous, connecting the now formed cusps. All the phenomena relating to internal
contact were now passed. I found it too difficult to estimate the instant of
" geometric " contact.
The recorded time, 19h. 30m. lis. by chronometer, when I was first sure of the
existence of the shadow, is the time I consider to apply best to the definition of
contact in the " instructions." I verified the minute. I can state positively that there
was no diminution of the Sun's light, or disturbance of the limb prior to 19h. 30m. 7s.
by chronometer. The illumination in the planet's atmosphere was, at first, almost as
bright as the last glimpse of the Sun's limb, but it was different altogether. It was
brightest at the sharp limb of the planet, of a different colour to the Sun's limb, and
faded off at its outer border. It was less than one second of arc broad, but might,
perhaps, have appeared a little broader had there been no cloud.
I now replaced the micrometer, and measured the distance between the cusps.
Replacing the negative eye-piece (210), I again saw the illumination in Venus'
atmosphere, but only on the upper or south portion of that part of the planet which
was outside the Sun. (I was sitting on the south side of the eye-piece, facing north,
the eye-piece being slightly inclined upwards.) It seemed to start from the Sun's
limb, and to extend some 60° or 70° along the south limb of Venus, about half a
second of arc broad, distinctly visible, though faint. On the other part of the
emerged half of Venus I could not detect the slightest trace of this illumination,
which I attribute to the effect of cloud ; but, from the persistency of the illumination
on the south side, it must have been very much brighter there than around the rest of
the emerged part. Later, its connexion with the Sun's limb ceased, but it still
remained visible.
At 19h. 45m. or 46m. I lost all trace of it.
During the observation of internal contact the wedge was used at about one-fourth
its length from the thin end. The brightness of the image was somewhat less than
the standard I had in my mind, but I saw best as it was. I shifted it small quantities
repeatedly.
At external contact I last saw the planet's sharp limb at 19h. 50m. 25s. by
chronometer.
61
Collecting the various times given, we have —
1. First suspicion of shadow
2. Shadow decided -
3. Sun's limb obscured
4. External contact
We therefore get finally for times of contacts —
Egress.
h.
m.
s.
19
30
7 by chronometer.
19
30
11
19
30
20
19
50
25
Chronometer Time.
Local Sidereal Time.
Local Mean Time. Greenwich Mean Time.
h. m. s.
h. m.
S.
h. m. s. h. m. s.
1. 19 30 7
12 32
13-23
19 30 13-68 8 1 0-80
2. 19 30 11
12 32
17-24
19 30 17-68 8 1 4-80
3. 19 30 20
12 32
26-26
19 30 26-68 8 1 13-80
4. 19 50 25
12 52
34-58
19 50 31-70 8 21 18-82
Whence the equations —
1. 6-576 =
2-251 Stt
+8R -
-8p +0-833 8a -0-430 8A -0-052 8*
2. 6-784 =
2-251 8x
+8R -
-8p +0-833 Sa -0-430 8A — 0-052 8*
3. 7-257 =
2-251 §;r
+8R -
-8a +0-834 8a -0-430 8A -0-052 U
4. 7-642 =
2-122 Stt
+3R +S p +0-854 8a -0-381 8A -0-055 U
Observations of the Contacts of the Sun and Venus.
Lieut. G. E. Coke.
Observed with a 4^-inch Cooke equatoreal ; power 215. A solar diagonal and dark
wedge, precisely similar to the arrangement on the 6-inch telescope, were used. Times
noted by chronometer Molyneux.
Egress.
The
I was seated on the south side of the telescope, the eye-piece being horizontal,
rice grains on the Sun were distinctly visible.
My wife counted seconds from the chronometer, and Mr. White, of the New Zealand
Telegraph service, recorded the time, taking the second from myself and the minute
from Mr. Hamilton, of the " Lyttleton Times."
At 7 a.m., December 7, I brought the chronometer Molyneux into my equatoreal
hut from its usual position in the electric house, it having been already compared by
Col. Tupman, and rehearsed a few imaginary observations to see that my assistants
thoroughly understood what each was to do. I instructed Mr. White to write in note
book, "First disturbance suspected;" against this the first time given was to be
placed, and the word " right " added if my suspicion was correct.
When Venus arrived within about a quarter of her diameter from the Sun's limb,
I began intently watching the space dividing the limbs, and on the first suspicion of
the slightest disturbance of the illumination of the Sun, I took the time, 19h. 28m. 43s.,
by chronometer, and, as this shadow became more decided, I told Mr. White to place
" right" against this time.
At 19h. 29m. 4s. by chronometer this shadow was decided, and about at its darkest,
but it never approached in the slightest degree to the darkness of the planet ; it was
never more than a hazy shadow.
At 19h. 29m. 12s. by chronometer the limbs of Venus and the Sun appeared to be
in geometrical contact, the dark body of Venus appearing to just touch the outline
of the Sun, which was sharp and well defined. I saw no appearance of an atmosphere
of Venus, except the slight shadow disturbing the illumination of the Sun before
contact. The limbs of both Venus and the Sun were fairly steady.
At external contact I took the time, 19h. 49m. 45s. by chronometer, when I ceased
to observe any break in the Sun's limb ; but I do not think that this observation
admits of much accuracy.
The Sun was covered by light cirrus clouds which became denser near contact.
Fortunately they cleared sufficiently just before contact to allow of a good observation
being made.
I 2
62
Collecting the various times, we have —
1. First disturbance suspected
2. Shadow darkest -
3. Geometric contact -
4. External contact
We therefore have for times of contacts —
Egress.
h. m. s.
19 28 43 by chronometer.
19 29 4
19 29 12
19 49 45*
Chronometer Time.
Local Sidereal Time. Local Mean Time. Greenwich Mean Time.
h. m. s.
1. 19 28 43
2. 19 29 4
3. 17 29 12
4. 19 49 45
h- m. s. h. m.
12 32 169 19 30
12 32 22-74 19 30
12 32 30-77 19 30
12 52 7-22 19 51
s. h. m. s.
2-17 8 49-29
23-17 8 1 10-29
31-17 8 1 18-29
4-25 8 21 51-37*
Whence the equations —
1. 5-980 =
2. 7-069 =
3. 7-499 =
4. 9-418*=
2-252 Sa- +8B, -8p +0-833 8a
2-251 oY +8R _8p +0-834 3a
2-251 8*- +8R -fy +0-834 8a
2-119 83- +8R +8p +0-854 8a
-0-430 8A —0052 Sif
-0-430 8 A -0-052 8*
-0-429 8A -0-052 8;!
-0-379 8A -0-055 8*
NEW ZEALAND.— NELSON.
Longitude of the station
Latitude
99 5>
h. m. s.
11 33 7*82 E. of Greenwich.
4°1 17 1-9 S.
Observations of the Contacts of the Sun and Venus.
Mr. A. S. Atkinson.
Observed with a 4-inch Browning refractor, 5 feet focal length ; power 167. First
surface reflecting prism and dark wedge, with which I made the field of just comfort-
able brightness. With the eye-piece either pushed in or pulled out a good way a
bright star presents a large circular disc, not sharply defined, but circular. Sirius or
Canopus shows also concentric dark rings on the disc, which within focus is edged
with purplish violet light, and without with greenish yellow. Venus in focus has
commonly a violet edging, especially with low powers. I have well divided
52 Orionis, and more easily the larger pairs in £ and A, and I have easily seen the
companion of Eigel in unsteady air and with the full Moon shining in a clear sky a
little below Aldebaran. The air here, in my experience, is commonly unsteady, but
on the majority of days very translucent. I followed Well's Comet up to 'and
including August 9, though Venus was awkwardly near, and my lowest power was 50 ;
then bad weather intervened, and I could not recover it afterwards among the small
nebula in Virgo, my telescope not being an equatoreal. On ordinary days and on the
morning of the transit I saw the granulations, by which I understand the general
dark mottling of the Sun's surface. Times noted by chronometer Porthouse.
Egress.
7 December 1882. Clear sky, but air not steady, and the Sun's limb considerably
agitated, and the planet also, though to a less extent. This agitation was well marked
immediately before what I have called inner contact, but it did not interfere with the
almost immediately subsequent observation of the planet's form, nor with the planet's
limb when showing above the Sun's, for I got a beautifully definite view of it.
* There appears to be something wrong with the time given for external contact ; it is 50 seconds later than
the mean time of all the New Zealand observers.
63
When Venus came close to the Sun's limb, so that I judged contact was imminent,
I saw that dark waves, as it were, were carried from her across the very narrow inter-
vening portion of the Sun's disc to his limb ; narrow symmetrical portions of the
preceding limb of the planet seemed to detach themselves and advance to the Sun's
limb, and there pass away.
I fixed my eye steadily on the Sun's limb, as nearly centrally to the advancing
planet as I could, and the moment I gave the first signal, 7h. 32m. 38s. by chronometer,
was the moment I saw that these dark waves, instead of passing away as before, had
suddenly adhered, as it were, to the Sun's limb, and had caused " a distinct and
permanent discontinuity in its illumination."
As soon as I was satisfied of this distinctness and permanence, and there was no
room for doubt, — there was no flickering at all after its first adherence, — I looked
below and found to my great surprise that it was not apparently the whole planet that
was adherent to the Sun's limb, but a large detached segment of it. Venus herself
seemed little, if at all, distorted so far as I could judge, being centrally underneath,
but separated by an interval of light, very thin in the central part, but widening of
course on each side, only, I should judge, that the upper limb of this apparent planet
was at least as far — I am satisfied was farther — from the limb of the Sun than the
limb of the undivided planet was some seconds earlier.
Having quickly taken this general view, I turned my attention to the dividing light
at its thinnest part. The apparent planet seemed to press upward and curve in ; the
chord of the segment and the two bodies were apparently touching along a considerable
part of the under side of the segment, but for a very faint white line between them,
though it looked more as if this line were marking their junction than separating
them. Still, I watched it as long as it remained. I thought it had disappeared at
7h. 33m. 6s. by chronometer, but it had not, and I was not certain that it had until
7h. 33m. 55s. by chronometer. After giving this last signal I looked up and saw the
upper limb of the segment clearly protuberant above the line of the Sun's limb, its
contour marked by a very faint line of grey light, and separating the Sun's cusps by
a considerable interval, — considerable, I mean, in proportion to the diameter of the
planet. I did not attempt a numerical estimate at the moment, but I believe the
proportion was about one-third. The notches in the sides of the planet caused by
the, as yet, incomplete junction — incomplete, that is, in lateral extent — between the
apparent planet and the segment were still distinctly visible beneath the limbs of
the Sun, that is, on his disc. I should say that in darkness of colour the segment was
absolutely indistinguishable both from what the fore part of the planet had been
before division and from the rest of it after division.
I left the telescope, described shortly to my assistants what I had seem, and in
illustration made an elementary diagram of the appearance and position of the segment
when I first discovered its separate existence. I asked Mr. M. W. Bichmond, who had
been calling time for me, to look for himself, and I adjusted the telescope for him ;
and even after this the remains of the notches were still visible, though a good deal
blurred, being then almost on the Sun's limb, and he saw them.
When these notches were filled up, and Venus was to the extent of perhaps one-
third of her perpendicular diameter off the Sun, the part still on the Sun was evidently
distorted, being somewhat pear-shaped, i.e., like the larger end of a pear, the part of
less diameter being that dividing the Sun's cusps. I saw no deformation in the part
off the Sun, even when as much as half-way off. The left upper quadrant was
beautifully marked by faint grey light along its edge.
I am perfectly satisfied that the time when I saw " the first appearance of any well-
" marked and persistent discontinuity in the illumination of the apparent limb of the
" Sun near the point of contact" was, as I have said, 7h. 32m. 38s. ± some moderate
fraction of a second. The discontinuity was established with considerable suddenness,
so that one slow to make up his mind could not be in doubt more than a small fraction
of a second ; (it was not a question of doubt at all, but of how long it took to perceive
the change. I passed direct from state of mind " it is going to happen " to the state
"it has happened" without going through the often intermediate one "I wonder
whether it has happened." The passage, if not instantaneous, was a very short one),
and the limits of error in recording could not, I think, be wide. While observing I
held a stop watch in my hand, which on making my first observation I set going, at
the same time calling the second I fixed on (7h. 32m.) 38s. When I first thought
I saw the "dividing light" disappear I stopped it, and gave the second signal
(7h. 33m.) 6s. On subsequent examination the watch showed exactly the recorded
interval, 28 seconds.
I 3
64
I am also quite satisfied, though this is rather inference than testimony, except so
far as it records the contemporaneous effect on my own mind, that the segment was
in fact the preceding limb and fore part of the planet, and the optical or other illusion
took effect in forming and retarding the apparent planet. I think that is the
legitimate inference from the facts I have stated, viz. : —
That when I first saw the apparent planet, its preceding limb was farther from the
Sun's limb than the limb of the undivided planet had been some seconds earlier.
That the segment caused and maintained a perfect discontinuity in illumination.
That the segment was altogether indistinguishable in darkness and, so far as it
went, in form from the planet.
That the line of disappearance of the dividing light was considerably below the
preceding limb of the segment, so that I had distinctly to look up from the former to
the latter, which was then well above the Sun's limb and there well defined.
For outer contact I fixed my attention on the lower part of the planet, and so gave
a certainly premature signal (7h. 51m. 47s.). After this I watched the apparent limb
of the Sun, which was trembling considerably. I thought contact had occurred at
7h. 52m. 9s., but continued watching, and 7h. 52m. 25s. I saw a minute hollow on
the part of the limb I was watching suddenly filled up and straightened in a way that
seemed to me quite different from the wave-like motion of the rest of the limb. This
is the way it struck me at the time. If I had to fix on one time for this contact I
should take the last ; it must be certainly, so far as I can speak, within the limits of
the two last. But I should attach little weight to either time singly, except so far as
it might be confirmed by other observers ; and I would say of the whole observation
of outer contact that it did not at the time, and does not now, carry one-fourth part
of the conviction to my own mind, of having seen what I was looking for, which I felt
on seeing what I have called inner contact.
Collecting the times relating to the contacts, taking last time for external contact,
we have —
h. m. s.
1. Inner contact - - - 7 32 38 by chronometer.
2. Outer .contact - - - 7 52 25
We therefore have —
Egress.
Chronometer Time. Local Sidereal Time. Mount Cook Mean Time. Greenwich Mean Time.
n » m - s. h. m. s. h. m. s. h m s
1. 7 32 38 12 36 30-04 19 40 28-52 8 1 22-61
2. 7 52 25 12 56 20-26 20 15-49 8 21 9-58
Whence the equations —
1. 7-674 = 2-254 fa + SB - o> +0-834 Sa -0-430 8A -0-052 U
2. 7-104 = 2-128 fa + 8E + 8p +0-853 8a -0-382 8A -0055 U
NEW ZEALAND.— DUNBDIN.
The longitude of the station, by exchange of signals with Col. Tupman., given in
Mr. Beverly's report is 7m. 10*7s, W. of Burnham, it is therefore—
h. in. s.
11 22 2-18 E. of Greenwich.
The latitude also supplied by Mr. Beverly is —
45 52 20 S.
Observations of the Contacts of the Sun and Venus.
Mr. A. Beverly.
Observed with a 3-inch telescope; power 100. The telescope, equatoreally
mounted, defines well ; distinctly separates the components of £ Aquarii in any
65
ordinary state of the atmosphere. About the time of internal contact the granular
structure of the Sun was plainly visible, especially near the spot cluster. At the time
of external contact the Sun had just emerged from a haze in the upper atmosphere,
and the definition was less perfect. Times noted by chronometer Arnold and Dent
628.
Egress.
At 7h. 30m. 46s. by chronometer the thread of light separating the limbs of the
Sun and Venus, having become excessively slender, appeared to part or darken
rather suddenly at the point of contact. No appearance of ligament or anything
analogous.
At 7h. 30m. 53s. a very faint ruddy line begins to appear between the cusps, which
are like fine needle points 6" or 7" apart.
At 7h. 31m. 12s. by chronometer ruddy line more distinct, longer and sensibly
arched.
7h. 50m. 51s. by chronometer, external contact.
The condition of the atmosphere was all that could be desired. There was nothing
of a prolonged or doubtful character about the phenomena at internal contact such as
we were led to expect, and there was no appearance of shading off or shadow before
the appearance of the cusps, which I take to arise from imperfect definition. The
luminous thread became gradually thinner and finer as the planet advanced, until it
was clearly obliterated at the first recorded time. Possibly the pink line joining the
cusps might have been a second or two sooner had I been on the look out for it. My
opinion is that the time of geometric contact falls between the first and second
recorded times — nearer the former — for this reason : if the aperture had been larger,
the definition being equally gcod, the luminous thread would have remained entire a
little longer, and the pink thread would have appeared a little sooner ; in fact, the
disappearance of the one and the appearance of the other might have taken place
simultaneously. At the third recorded time the planet was well over the Sun's limb.
The time of external contact is given when the last trace of indentation in the solar
limb disappears. It appears to me that under favourable conditions it is as definite
and reliable as the internal contact.
We therefore have —
Egress.
Chronometer Time.
Local Sidereal Time. Local Mean Time. Greenwich Mean Time.
h. m. s.
1. 7 30 46
2. 7 30 53
3. 7 31 12
4. 7 50 51
h- ni. s. h. m. s. h. m. s.
12 25 16-59 19 23 17-00 8 1 14-82
12 25 23-61 19 23 24-00 8 1 21-82
12 25 42-66 19 23 43-00 8 1 40-82
12 45 24-88 19 43 22-00 8 21 19-82
Whence the equations —
1. 7-270 =
2. 7-634 =
3. 8-621 =
4. 7-641 =
2-255 dv +8R, -8p +0-834 3a -0-428 8A -0-052 U
2-255 8*- +8R -8p +0-834 3a -0-428 8A -0-052 &
2-253 Stt +SR _8p +0-834 8a -0-428 8A -0-052 U
2-128 8* +8R +8p +0-854 8a -0-380 8A —0055 Si5
Observations of the Contacts of the Sun and Venus.
Mr. R. Gillies.
The telescope used was of 6 inches aperture, and equatoreally mounted, with power
used 150.
Egress.
The internal contact at egress came on very gradually,- the line of light getting
thinner and thinner till it, the line of light, became obscured distinctly and unmistak-
ably, which I took to be the contact, immediately after, possibly two seconds, complete
extinction of all light was seen where the thread of light had been, and at the same
moment I noticed that the limb of Venus was distinctly beyond the line of the disc of
I 4
66
the Sun ; there was a faint grey light on Venus. I would have noted this complete
extinction, but, at the moment, I felt so sure of the other being the right contact that
I did not note the time. I feel quite satisfied that the time noted is the contact, and
only mention the above to account for my not noting the time. The weather was all
that could be desired at about the time of contact, though, half an hour before, nothing
could be seen of the Sun, and had not been seen all the morning. The thin veil of
cloud then got thinner gradually, and at the time of contact, and for 10 minutes
before and after the external contact, the definition was as good as I ever saw it, the
thin veil of cloud tempering the light, and making both the Sun and Venus sharp and
clear. This was specially seen when Venus was half off the Sun, the points of the
notch being peculiarly sharp cut. There was no boiling, and no glare or sudden
alteration of light, and no motion Venus ; the black dot in the surrounding light
remained as steady as if stationary without my having to touch shade, focussing screw,
or clock strings ; everything went easily and right. I was seated in an easy posture
with the electric stop in my hand, and had no doubt of my signal. Another person
might have differed half a second, not more.
The contact external was not so clear ; it simply faded off the disc of the Sun, but
seemed to come and go at last. The time I noted was when the limb of the Sun was
complete and clear, but immediately after I saw like a darker short line on the edge of
the Sun, but it disappeared immediately, and, as something of the same thing
appeared before the time I marked, I did not note but the one. I now think that I
ought to have noted the last of these, and, therefore, probably the external contact is
noted by me too early. No rice grains were seen by me.
After the planet was well on the limb the planet seemed to appear to draw out
towards the limb into a pear shape, and I drew Mr. Keys' attention to it, and he
looked at it.
The times of contact are —
h. in. s.
, f Internal contact - - 12 22 4*8 by clock and chronograph.
\ „ - 7 29 27-5 by chronometer,
o J External contact - - 12 41 46*4 by clock and chronograph.
' \_ „ „ - 7 49 5*5 by chronometer.
Taking the mean of the times given by clock and chronometer, we get —
Egress.
Local Sidereal Time. Burnham Mean Time. Greenwich Mean Time.
h. m. s. h. m. 8. h. m. s.
1. 12 25 11-69 19 30 22-82 8 1 9-94
2. 12 44 53-14 19 50 1-04 8 20 48-16
Whence the equations —
1. 7-020=: 2-256 fa +3R — 8p +0-834 3« — 0-429 3 A -0*052 ^
2. 5-908= 2-132 fa + 3R +Sp +0-853 3a -0-381 3A -0-055^
Note to report on the Transit of Venus.
By the expression " complete extinction of all light," I do not mean that there was
jet black darkness, but that the obscured light which was between the planet and limb
of the Sun had become narrower and narrower till it was gone ; there always was a
sort of radiance or faint light in front of the planet, which now, I have no doubt, was
the atmosphere of Venus, though at the time I was too intent upon other things to
think what it was. It was this faint light that I saw distinctly beyond the line of
the disc of the Sun, and which in my report I call the limb of Venus. At the time I
thought it was the planet itself, slightly illuminated. I think now it must have been
its atmosphere. The touching of the disc of Venus on the limb of the Sun was quite
clear and distinct, and was what I took to be geometric contact, and at the same
moment as noted in my report. " I noticed the limb of Venus was distinctly beyond
67
the limb of the Sun." This is what must have been the atmosphere. I regret I did
not note this time as stated in my report.
(Signed) Eobert Gillies.
Dunedin, 8th January 1883.
Note. — The telescope was examined by Col. Tupman at Mr. Gillies' request, who
considers it to be affected by considerable spherical aberration. The
equations of condition have been discussed, both including and excluding
Mr. Gillies' observation, but the rejection of the observation scarcely
changes the resulting value of the parallax.
h. m. s.
Longitude of the station - 11 21 58*08 B. of Greenwich.
Latitude „ - 45 52 li S.
Observations of the Contacts of the Sun and Venus.
Mr. H. Skey.
Observed with a 9|~inch Browning reflector, first surface reflecting prism ; power 120,
and rather pale neutral tint dark head. The telescope shows well the granulations on
the Sun, but, owing to the slight cloud, they were not very noticeable during the
transit. The disc of a bright star when the eye-piece is pushed in within the focus is
perfectly circular, with the round black image of the flat in the centre. The same
appearance is presented when the eye-piece is pulled out an equal distance beyond the
focus. It divides 170 Canis Minoris easily, also y Centauri, and is guaranteed to
divide //, 2 Bootis. Times noted by chronometer Porthouse by Mr. A. H. Ross. In
addition to this, the times shown by an astronomical clock were noted by
Mr. J. K. Logan, inspector of telegraphs, and at the completion of the transit the
observed difference between clock and chronometer was found to correspond with
difference of times noted by the two observers.
Egress.
At 7h. 32m. Is. by chronometer Ahe limbs of the Sun and Venus seemed to make
a vibratory approach towards each <Jther, for the extremely thin thread of light broke,
and then joined again four or five times ; in other words, thin pointed and well-defined
cusps kept forming and then joining.
This flashing lasted three seconds by estimation when a straw coloured shade was
observed on the previously white disc of the Sun between the limbs of the Sun and
Venus, which rapidly passed through a brown to a nearly black shade, and completely
obscured the Sun's limb. At 7h. 32m. 9s. by chronometer, when geometrical internal
contact appeared complete, the Sun's limb was permanently discontinuous near the
point of contact.
The ligament arising from this contact was of the same shade of darkness as the
body of Venus and the background of the sky, that is, nearly black, and no change in
this colour was afterwards observed in any part of the ligament. The cusps at this
time were now blunted, and, when the leading limb of Venus was well off the Sun's
disc, the points of the cusps were cut off by straight shaded lines. No " black drop "
was observed, nor did Venus ever assume a " pear shape."
7h. 52m. 16s. by chronometer. Last external contact occurred.
There was a slight haze over the Sun during these observations, the clouds which
had obscured the Sun from its first r ising not being com pletely dissolved. This, how-
ever, had the effect of wonderfully improving the definition of the limbs of Venus and
the Sun, which were noticed to be equal to each other in sharpness of outline.
We have therefore —
Egress.
Chronometer Time. Local Sidereal Time. Burnham Mean Time. Greenwich Mean Time.
1. 7 32 1 12 24 48-50 19 30 3*78 8 5090
2. 7 32 9 12 24 56-52 19 30 1178 8 58-90
3. 7 52 16 12 45 6-83 19 50 18-78 8 21 5-90
22653.
K
68
Whence the equations —
1. 6-017= 2-258 St +SR -Sp +0-834 B« -0-429 SA -0-052 U
2. 6-434= 2-257 St +SE -Sp +0-834 5a -0-429 8 A -0-052 Si
3. 6-882= 2-130 St +3R +Sp +0-854 8« -0-380 SA -0-055 U
NEW ZEALAND.— NEW PLYMOUTH.
h. m. s.
Longitude of the station - 11 36 17*55 B. of Greenwich.
Latitude „ - 39 4 0-8 S.
Observations of the Contacts of the Sun and Venus.
Mr. T. Humphries.
Observed with a 4-inch telescope by Cooke ; power 200. Times noted by a chrono-
meter by Mr. T. K. Skinner. The telescope is a very good one, and with the
power 200 gave fair definition, and granulations were plain on the Sun's surface.
Egress.
h. m. o.
7 37 17 by chronometer. Joined, light haze.
7 37 30 „ „ Contact. Might have been a second earlier ; should
say certainly to two seconds ; under rather than
over.
7 37 56 „ „ Limb of Venus outside, and distinct ring of light
on it.
I used the word joined to distinguish it from " contact." A dark haze appeared
between the limbs, which I thought was going to merge into " black drop," but five
seconds after I called " off again," as clear light appeared.
There were passing clouds throughout the morning, and the Sun was obscured for
some minutes previous to 7h. 33m., when it cleared. At 7h. 34m. I have noted
"great vibration," and at 7h. 36m. steady again.
The appearance at contact was not as clear and marked as I should have wished,
as for a moment or two previous the band of clear sunlight seemed to flicker between
the limbs, but was shut off instantaneously. This was the time I took for contact.
We get for time of contact therefore —
Egress.
Chronometer Time. Local Sidereal Time. Mount Cook Mean Time. Greenwich Mean Time.
h. m. s. h. m. s. h. m. s. h. m. s.
7 37 30 12 39 45*76 19 40 34-49 8 1 28-58
Whence the equation —
7-963 = 2-256 Stt + SB, - 6> +0-833 Sa -0-431 8A -0-052 U
The latitude of the station is assumed to be 39° 3' 57" S. ; the longitude the same
as Mr. Humphries' station.
Observations of the Contacts of the Sun and Venus.
Mr. A. O. N. O'Donahoo.
Observed with a 2f-inch telescope by Elliott Bros.; power 110. The neutral-
coloured glass used gave a bright and distinct image, enabling me to speak confidently
as to the time of the appearance of contact within a couple of seconds.
r><)
Egress.
h. m. s.
7 37 44 by watch. No drop ; no granulations visible. No phenomenon of
any kind whatever on the surface of the Sun.
The contact might have been one second later than the time given ; it was a pure
geometrical one, with very good definition. There was no haze of any description at
the time of contact.
Mr. O'Donahoo's watch was fast of Mr. Humphries' chronometer —
h.
m.
S.
At 19
- 18-0
„ 20
15
- 17-0
We therefore have —
Egress.
Watch Time. Local Sidereal Time. Mount Cook Mean Time. Greenwich Mean Time.
h. m. s. h. m. s. h. m. s. h. m. s.
7 37 44 12 39 42-25 19 40 30-99 8 1 25-08
Whence the equation —
7-791 = 2-256 8tt + 8R - 8p +0-833 8« -0-431 SA -0-052 3*
HOBART.
h. m. s.
Adopted longitude of the station - 9 49 19*53* B. of Greenwich.
Latitude - - - - 42 53 24 S.
Observations of the Contacts of the Sun and Venus.
Mr. E. J. White.
Observed with a 4^-inch Cooke equatoreal, negative eye-piece ; power 200, with
Herschel's prism and neutral glass wedge. The grainy structure of the Sun was not
perceptible, but tolerable definition of a scattered group of small spots was obtained.
Venus did not exhibit any well-marked distortion ; the only imperfection of figure was
her serrated edges, due to atmospheric disturbance. The remark about the grainy
structure of the Sun applies to about the middle time between the contacts. A few
minutes after the last contact the structure was very distinct about the centre of the
Sun. Times taken by chronometer Molyneux by Mr. White himself, who also wrote
down his own notes ; but as each note was entered, Captain Shortt, R.N., who acted
as assistant, noted the times by his mean time chronometer as a check against
mistakes.
Egress.
Sun rose in nearly clear sky behind trees, and was occasionally for the first half
hour hid behind stratus clouds. After this the sky was quite free from clouds during
the whole of the transit. At 16h. 41m. Sun had risen sufficiently high to be seen over
the base of revolving dome, and Venus was well seen, although the images were
boiling excessively. Throughout Venus appeared very black about the centre, and
dark indigo colour near her edges.
* Mr. White gives 9h. 49m. 20'5s. E. as the longitude of the station ; but since receiving the report a new
value for Melbourne has been obtained, and, assuming Mr. White's longitude to be founded on the former value
of Melbourne, the corrected longitude becomes 9h. 49m. 19*53s. E. of Greenwich.
K 2
70
h. m.
10 53 33*8 by chronometer. Internal contact observed tangentially. Venus
serrated, but appeared generally round. No
black drop or ligament seen.
10 59 „ „ Up till this time a ring of light was seen round
Venus (the part off the Sun). After this it
extended only about three-quarters round the
limb off the Sun.
11 2 50 „ „ Venus appeared about half off the Sun. Ring of
light only seen on apparent right-hand edge,
extending about 60°.
11 8 „ „ No ring visible round Venus.
11 13 25*6 „ „ External contact observed at egress.
We have therefore —
Egress.
Chronometer Time. Local Sidereal Time.
Local Mean Time.
Greenwich
Mean Time.
h. m. s.
h. m. s.
17 51 46-22
8 2 26-69
18 11 34-76
8 22 15-23
h. m. s. h. m. s.
1. Internal 1 1Q 53 33 . 8 10 53 46-00
contact I
2. Externally 13 25>6 n 13 37 . g0
contact J
Whence the equations —
1. 8-190 = 2-570 &r + 8R - 8p +0-836 8« -0-425 SA -0-052 U
2. 7-382 = 2-496 8r + SR + fy +0-855 Sa -0-377 8A -0-054 U
MELBOURNE OBSERVATORY.
h. m. s.
Longitude - - - 9 39 5383 E. of Greenwich.
Latitude - - - 37 49 53-4 S.
Observations of the Contacts of the Sun and Venus.
Mr. R. L. J. Ellery.
Observed with the 8-inch equatoreal of the Melbourne Observatory ; power 230.
Egress.
Morning overcast and gloomy at 4 a.m., with S.E. scud and dense clouds. At 17h.
there were some signs of clouds breaking, and at 17h. 5m. the Sun broke through
clear, showing Venus about four diameters from the Suns limb. Edges of both/Sun
and Venus boiling violently. No markings on Venus visible. When about 1^ diameters
from Sun's limb got measures of distances with double-image micrometer ; limbs were,
however, very disturbed. Changed eye-pieces and watched for contacts at 17h. 17m.
Just before contact there was a flickering junction of the limbs, and then an appearance
like B ally's beads, quite distinct, but flickering for some seconds. Contact was taken
to be when the solar light flickering around the edge of Venus ceased to show broken
beads of light, and immediately after a break in the Sun's limb was apparent. As the
advancing limb of Venus emerged from the solar disc, a clear thread of silvery light
was continued around it, — a very thin thread. No markings on Venus. At 17h. 53m.
first saw a pale halo, or rather disc, of uniform light, very dim, but with a sharp
outline symmetrically surrounding Venus outside Sun's disc. Estimated radius =
three diameters of planet, very distinct at 17h. 54m. As the planet passed off the
Sun the thread-like illumination of advanced edge of Venus disappeared, except on
the right-hand advanced side.
71
This light continued, but became more contracted but brighter, nearly until
external contact. At 17h. 58m. Os., local mean time, it was quite detached from
Suns limb.
Halo still apparent at 17h. 58m., but disappeared at 3^ minutes before external
contact.
External contact. Edge of Sun disturbed, but the discontinuity of limb caused by
planet well marked until time given, when the undulations on the edge of Sun
assumed one uniform character all around. The boiling prevented anything like a
precise geometric contact, but at the same time the phenomena were marked with con-
siderable clearness by the want of uniformity or otherwise of the regular undulations
around the Sun's disc.
Mr. Ellery's times are —
Egress.
Local Sidereal Time.
Local Mean Time.
Greenwich Mean Tim
1.
2.
3.
h. m. s.
First contact - 10 44 40-80
Distinct break| 10 ^ ^
m bun s limb J
Last contact - 11 4 9-15
h. in. s.
17 42 40-96
17 42 50-78
18 2 6-12
h. m. s.
8 2 47-13
8 2 56-95
8 22 12-29
Whence the equations-
1. 8-517 = 2-652 fa + 8R - Sp +0-835 8a -0-426 SA -0-052 U
2. 9-043 = 2-652 fa + SB, - 8p +0-835 Sa -0-426 SA -0-052 U
3. 6-356 = 2-595 fa + 3R + 8p +0-854 3a -0-379 8A -0-054 U
Observations of the Contacts of the Sun and Venus.
Mr. J. E. Gilbert.
Observed with a 4|-inch Simms' equatoreal ; power 140.
Egress.
Caught first glimpse of Venus on Sun's disc at 17h. 3m. (mean time). Its form was
very much blurred and boiling ; colour blue furthest edge from Sun's limb, and purple
nearest edge, centre deep violet ; Sun's limb boiling ; the objects gradually improving
in appearance, the Sun's limb the most. At three minutes before contact a narrow
luminous halo surrounded the planet, its form improving wonderfully, being almost;
circular, the boiling very trifling. Cave two (2) dots on chronograph, the first wlieii
a Chinaman s cap first formed ; the second, apparent contact of limbs. Cave dots after.
The outline of the planet could be traced by a faint but sharply- defined luminous edge,
until it was about three parts off the Sun. The edge of the Sun was still boiling at
time of last contact.
The times given are —
Egress.
Local Sidereal Time. Local Mean Time. Greenwich Mean Time*
h« ni. s. h. m. s. h. m. s.
1. First contact - 10 44 42-38 17 42 42*54 8 2 48*71
2. Last contact - 11 3 59-63 18 1 56-63 8 22 2-80
Whence the equations —
1. 8-605 = 2-652 fa + 8R - 3p +0-835 8a -0*426 8A -0-052 St
2. 5-845 = 2-595 fa + 3R + Sp +0*854 3a -0*379 3A -0'054 Si
K 3
72
NEW SOUTH WALES.— WBNTWORTH.
h.
9
m. s.
27 37-18 B. of Greenwich.
Longitude of the station
Latitude • „ - 34 6 24-7 S.
Observations of the Contacts of the Sun and Venus.
Mr. C. Todd, C.M.G.
Observed with an excellent equatoreal, having 4^ inches aperture, purchased from
the late Mr. B. H. Babbage, who brought it from England after the death of his
father the late Mr. 0. Babbage, to whom it formerly belonged.
Egress.
The Sun rose in an unclouded sky on the day of the transit, and the circumstances
were all one could desire. Near the time of internal contact the limb of Venus
became somewhat distorted or slightly drawn out towards the edge of the Sun, and
it was rather woolly ; the Sun's limb too was occasionally boiling, but I think I
succeeded in getting the times of the different phases as exact as the nature of the
observation will admit.
1. December 6d. 17h. 30m. 15s., "Wentworth mean time. A few excessively thin
ligaments appeared at this instant to connect the limb of the planet with that of the
Sun, and the streak of light round the limb was never again sensibly continuous,
although the planet was well on the Sun.
2. 17h. 30m. 58*6s. The ligaments, which have been gradually thickening since the
last time noted, have now closed, and the contact now seems tangential.
17h. 32m. 7h. The appearance was very much as shown in enclosed rough sketch.
Evidently partly off limb now.
1 7h. 50m. 7s. Sun's limb seems to be still slightly notched.
3. 17h. 50m. 17s. Limb perfect. Noted for external contact.
I should mention that the planet when well on the Sun was sensibly oval, and
appeared of a greyish black colour.
Collecting the times relating to the transit, we have
Egress.
Local Sidereal Time.
Local Mean Time.
Greenwich Mean Time.
1.
2.
3.
h. m. s.
10 32 14-82
10 32 58-54
10 52 20-11
h. m. s.
17 30 15-00
17 30 58-60
17 50 17-00
h. m. s.
8 2 37-82
8 3 21-42
8 22 39-82
Whence the equations —
1. 7-578 = 2-705 Stt + 8R — 3p +0*835 3a -0-427 8A -0*052 U
2. 9-831 = 2-704 Sv + 8R - 8p +0-835 3a -0-425 3A -0-052 U
3. 7-256 = 2-659 oV + 8R + 8p +0-854 3a -0-379 8A -0-054 8/
NEW ZEALAND.— AUCKLAND.
The position of Captain Heale's station has been kindly supplied by Mr. McKerrow,
Surveyor-General of New Zealand, viz. : —
The longitude given is 9m. 56*52s. E. of Burnham ; therefore it is —
h. m. s.
11 39 9-40 B. of Greenwich.
The latitude determined by Mr. Adams is —
36 51 9-6 S.
73
Observations of the Contacts of the Sun and Venus.
Captain T. Heale.
Observed with a 5-inch refractor, 6 feet focal length, equatoreally mounted on a
brick pedestal ; power 115.
Egress. — External Contact.
About 6 in the morning the planet was seen very clearly on the Suns disc, but as
she approached the limb the low misty stratus cloud, which more or less covered the
whole heavens, thickened, and the Sun was not seen. At 12h. 48m., sidereal time,
the planet was seen through the thin mist clearly, but without dark glass, her image,
as well as the Sun's limb, perfectly well-defined and without the least distortion ; the
cusps of light quite sharp. It continued to be seen quite clearly till exit. At first
there was so little brightness that I found it necessary to use a low power (115) in
order to get sufficient light. When near the external contact it became brighter, and
I should have been glad to have had a rather higher power, but I was afraid to shift
the eye-piece.
At 13h. 2m. 45s. by chronometer I could still distinctly see the indentation of the
Sun's limb ; two seconds later its appearance became doubtful, and at 49s. the edge of
the limb was certainly perfectly uniform. I noted the last time as that of the contact,
but possibly one second earlier may be the true time. It is certainly true within
two seconds. I therefore take as the moment of separation —
h. m. s.
13 2 48 by chronometer.
Captain Heale gives his chronometer at time of the transit 35s. fast of local mean
time. We therefore get —
Egress. — External Contact.
Chronometer Time. Local Sidereal Time. Local Mean Time. Greenwich Mean Time.
h. m. s. h. m. s. h. m. s. h. m. s.
13 2 48 13 2 13-00 20 10-18 8 21 078
Whence the equation —
6-594 = 2-131 oV + m + Sp +0-852 Sa -0-384 SA -0-055 3*
RESIDUAL EQUATIONS AND DISCUSSION OF INGRESS
OBSERVATIONS.
Ingress. — Observations near "External" Contact.
Collecting the results and arranging them in order of their parallax factors we have,
taking the earliest times at which Venus was seen as the time of external contact, the
following equations of condition : —
Equation of Condition
Station. Observer. with Residual.
Adopted Data.
1. Mauritius - - Dr. C. Meldrum - - 5-836 = -2-160 3*- + 8s +d ; 243
2. Madagascar - Commander P. Aldrich - 6-989 = —1-998 &r + 8s +1-410
3. Aberdeen Road, Mr. Finlay - - 4-086 = —1-774 8* + 8s —1-473
Cape of Good
Hope.
4. Mr. Pett - - - 3-929 = -1-774 8sr + 8s -1-630
5. Montagu Road, Mr. Marth - - 5-404 = -1-683 8t + 8s -0-147
Cape of Good
Hope.
6. Mr. Stevens - - 7-263 = -1-683 8* + 8s +1-712
K 4
74
Station.
Cape of Good Hope,
Royal Observa-
tory.
Observer.
Dr. Gill
Dr. Blkin -
Mr. Pillans
Captain Jurisch
Equation of Conditi<
with
Adopted Data.
Dn
+ 8s
+ 8s
+ 8s
+ os
Residual.
7.
8.
9.
10.
- 4-933 = -1-658 fa
- 2-087 = -1-658 St
- 6-342 = -1-658 oV
- 7-546 = -1-658 fa
-0-615
-3461
+0-794
+1-998
11.
Strait of Magellan -
Captain Wharton
- 6-864 = -0-625 fa
4- 3s
+1-409
12.
Barbados
Lieut. Thomson
- 6-566 = +1-929 fa
+ 8s
+1-341
13.
14.
Jamaica
Dr. Copeland
Captain Mackinlay
- 4-539 = +2-278 fa
- 4-009 = +2-278 fa
+ OS
+ 0S
-0-655
-1-185
15.
Mr. Hall
- 4-917 = +2-296 fa
+ OS
-0-275
16.
17.
Bermuda
Mr. Plummer
Lieut. Neate
- 4-984 = +2-455 fa
- 5-319 = +2-455 fa
1 ^
+ OS
+ &
-0-194
+0-141
18. Ottawa - - Mr. Blake - - - 5-747 = +2-697 8* + 8s +0-591
Solving the above by the method of least squares, we find —
to = -0-090
and—
3s = 5-399
Therefore —
t = 8-760 ± : 122
The separation of the centres of Venus and Sun at this phase is —
1001-1
If we exclude the observation of Dr. Elkin, we have —
Equations of Condition with
Adopted Data.
1.
2.
3.
4.
5.
6.
7.
9.
10.
11.
5-836
6-989
4-086
3-929
5-404
7-263
4-933
6-342
7-546
6-864
■2-160 to
• 1-998 to
■1-774 to
-1-774 to
■1-683 to
• 1-683 to
-1-658 to
■1-658 to
■1-658 to
■0-625 to
+
+
+
+
+
+
+
4-
+
8s
8s
8s
8s
8s
8s
8s
8s
8s
+ 8s
12.
6-566
13.
4-539
14.
4-009
15.
4-917
16.
4-984
17.
5-319
18.
5-747
+1-929 to + 8s
+2-278 to + 8s
+2-278 to + 8s
+2-296 to + 8s
+2-455 to + 8s
+2-455 to + 8s
+2-697 to + 8s
Residual.
-0-141
+ 1-040
-1-824
-1-981
-0-490
+1-369
-0-957
4-0-452
+1-656
+1-154
+1-301
-0-665
-1-195
-0-284
-0-190
+0145
+0-616
From which we get —
Therefore —
8s =
■0-174
5-601
7T = 8-676 +. 0-106
75
Ingress. — Residual Errors from Times observed near the Internal Contact.
Station.
1. Mauritius
2. Madagascar
3.
4.
5.
6.
7.
8.
9.
10. Durban
11. Aberdeen Road, Cape
of Good Hope.
12.
13.
14. Montagu Road, Cape
of Good Hope.
15.
16.
17.
18.
19. Cape of Good Hope,
Royal Observatory.
20.
21.
22.
23.
24.
25.
26.
27.
28.
29.
30.
31.
32.
33.
34.
35.
36.
37. Strait of Magellan -
38.
39. Barbados
40.
41. Jamaica
42.
43.
OW
Equations of Condition.
Dr. Meldrum
Rev. S. J. Perry
Rev. W. Sidgreaves
Commander P. Aldrich -
Mr. Neison
Mr. Finlay
Mr. Pett
Mr. Marth
Mr. Stevens
Dr. Gill -
Mr. Maclear
Dr. Blkin -
Mr. Freeman
Mr. Pillans
Captain Jurisch
Captain Wharton -
Mr. Talmage
Lieut. Thomson -
Dr. Copeland
Captain Mackinlay
Dr. Pearson
3-022 = -2-142 fa 4- Ss
-0-782
2-837
3-402
1-223
2-493
2-740
1-371
2-977
-2-003 fa
-2-003 fa
-2-003 fa
-2-003 fa
-2-003 fa
-2-003 fa
-2-003 fa
-2-003 fa
+ 8s
4- 8s
4- 8s
4- 8s
4- 8s
4- 8s
+ 8s
4- 8s
3-225 = -1-903 8*- + 8s
-0-689 = -1-824 &r 4- 8s
2-999 = -1-827 fa + 8s
3-201 = -1-827 fa 4- 8s
1-519 = -1-743 fa 4- 8s
3-159 :
-0-560 :
1-477 :
[3-118]:
-1-745 fa 4- 8s
■1-741 fa + 8s
•1-743 fa 4- 8s
• 1-745 fa + 8s
0-895 = -1-722 fa 4- 8s
2-664
3-655
0-226
2-427
4-339
-0-105
3-063
3-720
3-983
2-891
3-753
2-014
2-382
4-015
1-914
3-216
4-063
1-840
3-339
1-631
1-417
2-941
2-310
•1-723 8;r
■1-724 8tt
721 fa
723 8tt
724 8tt
721 fa
723 fa
724 8*-
724 fa
723 fa
1-724 fa
1-723 fa
1-723 fa
1-724 fa
1-723 fa
1-724 fa
1-724 fa
4- 8s
4- 8s
4- 8s
4- 8s
4- 8s
4- 8s
4- 8s
4- 8s
4- 8s
4- 8s
4- 8s
4- 8s
4- 8s
+ 8s
4- 8s
4- 8s
+ 8s
-0-745 fa 4- 8s
-0-749 fa 4- 8s
4-1-843 fa 4- 8s
4-1-843 fa 4- 8s
4-2-195 fa 4- 8s
4-2-196 fa + 8s
2-942 = 4-2-197 fa + 8s
The observations of Mr. Freeman, equations 29 and 30, were made with a power
of 74 ; those of Captain Jurisch, equations 34 to 36, with a telescope whose object-
glass was only 24; inches in diameter.
A 32653.
Ii
76
Station.
Observer.
Equations of Condition.
44.
45.
46.
Jamaica
Mr. Hall
Mean adopted by
Hall.
Mr.
3-203 = 4-2-215 oV + 8s
4-083 = +2-215 oV + 8s
3-643 = +2-215 oV + 8s
47.
48.
49.
50.
51.
52.
Bermuda
Mr. Plummer
Lieut. Neate
-
1^00 = +2-403 hr + 8s
2-371 = +2-402 oV + 8s
3-049 = +2-402 oV + 8s
1-390 = +2-403 oV + 8s
1-835 = +2-403 8x + 8s
2-828 = +2-402 8*- + 8s
53.
Cambridge, U.S.A. -
Mr. Jewett
-
1-324 = +2-615 S,r + 8s
54.
55.
Kingston, Canada -
Mr. Williamson
-
0-211 = +2-672 8*- + 8s
2-949 = +2-671 8a- + 8s
56.
Ottawa, Canada
Mr. Blake
■
2-557 = +2-675 %r + 8s
4
Ingress. — Internal Contact.
In discussing these equations it will probably be desirable not to include Dr. Elkin's
observations (equations 25-28), as it was observed with half the object-glass of a 4-inch
heliometer, and, therefore, may be considered to have been made under different
circumstances from the rest of the observations. Dr. Elkin's observations, however,
agree very closely with the mean results. The times of contacts noted by Mr. Stevens
at Montague Road, Cape of Grood Hope (equation 17), and by Mr. Talmage, at
Barbados (equation 39), are very early, and appear to refer to the phase noted by other
observers as " Geometric or Apparent Contact." Including these, we have 13 equations
of geometric or apparent contact as follows : —
Equation of Condition.
Residual.
2.
5.
8.
14.
17.
34.
37.
39.
40.
47.
50.
53.
54.
-0-782
+1-223
+1-371
+1-519
+1-477
+1-914
+1-840
+1-631
+1-417
+1-700
+1-390
+1-324
+0-211
-2-003 8tt
-2-003 8tt
-2-003 8*-
-1-743 8x
-1-743 8*-
-1-723 8?r
-0-745 8tt
+1-843 8*-
+1-843 8*-
+2-403 8*-
+2-403 8tt
+2-615 8tt
+2-672 8tt
+
+
+
+
+
+
+
+
+
+
+
+
+
8s
8s
8s
8s
8s
8s
8s
8s
8s
8s
8s
8s
8s
-1-980
+0-025
+0-173
+0-315
+0-273
+0-710
+0-612
+0-341
+0-127
+0-397
+0-087
+0-016
-1-098
Which gives-
Therefore —
8tt +0-024,
and 8s 1-246.
= 8-874 ±0-066.
77
The angular separation of the centres of Venus and the Sun at this phase is about
941"'4. Or, if we reject the observations of Messrs. Stevens (equation 17) and Talmage
(equation 39), the equations are —
Residual.
2.
-0-782 =
-2-003 8x
+ 8s
-1-925
5.
+1-223 =
-2-003 8*-
+ 8s
+0-080
8.
+1-371 =
-2-003 8*-
+ 8s
+0-228
14.
+1-519 =
-1-743 8tt
+ 8s
+0-370
34.
+1-914 =
-1-723 8tt
+ 8s
+0-765
37.
+1-840 =
-0-745 8tt
+ 8s
+0-668
40.
+1-417 =
+1-843 8tt
+ 8s
+0-186
47.
+1-700 =
+2-403 hr
+ 8s
+0-456
50.
+1-390 =
+2-403 8*-
+ 8s
+0-146
53.
+1-324 =
+2-615 8*-
+ 8s
+0-075
54.
+0-211 =
+2-672 8*-
+ 8s
-1-040
Whence —
fa = +0-023
Zs = 1189,
or —
it = 8-873 ±0*081,
which agrees very closely indeed with the value obtained before.
Rejecting the observations of Father Perry and Mr. Williamson (equations 2 and 54),
which may refer to some other phase, for they agree closely with the contact of limbs
as observed by Messrs. Finlay, Stevens, and Elkin (equations 11, 16, and 25), the
equations become —
Residual.
5.
+1-223 =
-2-003 8tt
+ 8s
-0-322
8.
1-371 =
-2-003 hr
+ 8s
-0-174
14.
1-519 =
-1-743 8*-
+ 8s
-0-024
17.
1-477 =
-1-743 8*-
+ 8s
-0-066
34.
1-914 =
-1-723 &r
+ 8s
+0-371
37.
1-840 =
-0-745 8x
+ 8s
+0-305
39.
+1-631 =
+1-843 8*-
+ 8s
+0-117
40.
1-417 =
+1-843 8t
+ 8s
-0-097
47.
1-700 =
+2-403 8tt
+ 8s
+0-190
50.
1-390 =
+2-403 8tt
+ 8s
-0-120
53.
1-324 =
+2-615 8?r
+ 8s
-0184
From which we get —
or —
8?r = -0-008
8s = 1-529,
*- = 8-842 ± 0-028.
L 2
78
Finally, rejecting the observations of Father Perry and Mr. Williamson (equations 2
and 54), and also Messrs. Stevens and Talmage (equations 17 and 39), we have-^-
Residual.
From these we get —
Therefore-
5.
+1-223
= -2-003 Stt + 8s
-0-334
8.
1-371
= -2-003 dV + h
-0-186
14.
1-519
= -1-743 3*- + 8s
-0-034
34.
1-914
= -1-723 8tt + 8s
+0-361
37.
1-840
= -0-745 8x + 8s
+0-304
40.
+ 1-417
= +1-843 8x + 8*
-0-076
47.
1-700
= +2-403 &r + 8s
+0-216
50.
1-390
= +2-403 8tt + 8s
-0-094
53.
1-324
= +2-615 8tt + 8s
8tt = -6-017
8s = 1-524.
-0-156
8-833 ±0-036,
Mhich is the smallest result these apparent contacts admit of.
The results from apparent contacts of the atmosphere of Venus and the Sun are,
therefore, confined within the limits —
7t =8-833 and tt =8-874,
and the value-
tt =8-873 ±0-081
is that obtained without the rejection of any observations which profess to be " contacts
with the atmosphere of Venus " or " the first appearance of light through the atmos-
phere of Venus," as distinguished from the "real internal contact."
These contacts appear to have taken place with an angular separation of the centres
of Venus and the Sun of about 941"-4.
The principal internal contact to which the observer's attention was directed was
defined in the " Instructions " as follows : —
" The time of the last appearance of any well-marked and persistent discontinuity in
the illumination of the apparent limb of the Sun near the point of contact."
" The expression ' well-marked and persistent discontinuity in the illumination of the
apparent limb of the Sun near the point of contact ' is intended to guard observers
against giving times for the contacts when there may be a suspicion only of some slight
disturbance, haze, shadow, or interference phenomena. It is a point of primary
importance that all the observers shall, as far as possible, observe the same kind of
contact ; and it is therefore desirable that the times recorded for contacts should refer
to some marked discontinuity in the illumination of the Sun's limb, about which there
cannot be a doubt, and which may be supposed to be recognisable by all the
observers/'
The last times given by the observers at the Eoyal Observatory, Cape of Good Hope,
are very late compared with all the other observations, as will be seen by the following
comparison with observations which have parallax factors of the same sign and nearly
of the same magnitude.
The residuals for the last recorded times at the Eoyal Observatory, Cape of Good
Hope, are as follows : — -
21.
24,
30.
33.
36.
Mean
3-655
4-339
3-753
4015
4-063
3-965
- 1-724 8tt
-1-724 Stt
-1-724 Stt
-1*724 8tt
-1-724 8tt
-1-724 8tt
+ 8c
+ 8c
+ 8c
+ 8c
+ 8c
+ 8c
79
Dr. Elkin, who observed with a heliometer, and whose observation is not therefore
included with those made with the equatoreals, gives a residual—
3-983 = -1-724 &r + 8c.
The corresponding residuals for the other stations, neglecting Stevens observation,
whose residual is —
1-477 = -1-743 8tt + &,
are as follows :
Mean
1.
3-022 =
-2-142 aV
+ h
3 and 4.
3-120 =
-2-003 &r
+ 8s
7.
2-740 =
-2-003 3tt
+ 3s
9.
2-977 =
-2-003 Stt
+ 8s
10.
3-225 =
-1-903 §tt
+ 8s
12.
2-999 =
— 1-827 &r
+ 8s
13.
3-201 =
-1-827 Stt
+ 8s
15.
3-159 =
-1-745 &r
+ h
38.
3-339 =
-0-749 Stt
+ 8s
-
3-087 =
-1-800 Stt
+ 8s
Mean
The difference, 0*878, = +0-076 §7r -f h — §s, appears therefore almost entirely
due to a difference 80 — 85, or difference of phase. Mr. Grill, when in England, was
consulted by Mr. Stone in the matter, and in reply sent a letter, of which the following
is a copy : —
" When I communicated my report on the Transit of Venus observations made at
the Cape Observatory in 1882 I wrote you privately, offering to state what, in my
opinion, were the true times of contact. My report naturally had reference solely to
official instructions, — instructions which were followed by myself and my assistants as
accurately as possible. You now ask that I should communicate the opinion previously
offered, and state what 1 consider to be the true time of contact.
" I have no hesitation in saying that 3h. 25m. 47'5s.,* Cape M.T., represents the
phase which would have been followed by a well-marked and persistent discontinuity,
if the definition had been good ; but there was a south-easter blowing at the time,
and, as is usually the case in such circumstances, the images were vibrating rapidly,
and definition was very unsatisfactory.
" Thus whilst there remained a * well-marked and persistent discontinuity in the
illumination of the apparent limb of the Sun near the point of contact' till
3h. 26m. 6'9s. C.M.T., which was seen by all the observers at the Cape Observatory,
I have no hesitation in saying that this was due to the atmospheric conditions above
referred to. The change of colour which E have described at 3h. 25m. 47'5s. is really
the only phase that is nearly independent of atmospheric conditions. The phase of
4 well-marked and persistent discontinuity of illumination ' follows that phase at an
interval which is a function of the state of definition. If therefore you reject entirely
the Cape Observatory phase 3h. 26m. 6*9s., it will be necessary to reject similar late
phases depending upon bad definition in the northern hemisphere.
" You will find on the first page of my Report the phases for the other Cape
observers, which, in my opinion, correspond with the above-mentioned phases.
" Yours very truly,
" (Signed) David Gill."
Father Sidgreaves writes that his last recorded time is his " real contact."
A letter from Father Perry states that he wishes the mean of his latest times
(equations 3 and 4) to be taken as the time of real contact. We therefore have, in
accordance with the preceding instructions, and taking last times given by Mr. Plummer
* The observation used in the final equation,
L 3
80
and Lieut. Neate, and including the observations of Messrs. Stevens and Talmage, the
following 24 equations : —
Residual.
1.
3-022 =
-2-142 &r
+ 8s
+0-173
Mean of 3 & 4.
3-120 =
-2-003 8:r
+ 8s
+0-130
7.
2-740 =
-2-003 8*-
+ 8s
-0-107
9..
2-977 =
-2-003 &r
+ 8s
+0-273
10.
3-225 =
-1-903 &r
+ 8s
+0-380
12.
2-999 =
-1-827 Stt
+ 8s
+0-155
13.
3-201 =
-1-827 Sx
+ 8s
+0-357
15.
3-159 =
-1-745 Stt
+ 8s
+0-316
17.
1-477 =
-1-741 8tt
+ 8s
-1-366
20.
2-664 =
-1.723 &r
+ 8s
-0-179
23.
2-427 =
-1-723 &r
+ OS
-0-416
29.
2-891 =
-1-723 Stt
+ 8s
+0-048
32.
2-382 =
-1-723 Stt
+ 8s
-0-461
35.
3-216 =
-1-723 8tt
+ OS
+0-373
38.
3-339 =
-0-749 8*-
+ 8s
+0-511
39.
1-631 =
4-1-843 8tt
+ 8s
-1-157
41.
2-941 =
+2-195 8*-
+ 8s
+0-159
42.
2-310 =
+2-196 8tt
+ 8s
-0-472
43.
2-942 =
+2-197 8*-
+ 8s
+0-160
46.
3-643 =
+2-215 8x
+ 8s
+0-861
49.
3-049 =
+2-402 Stt
+ 8s
+0-270
52.
2-828 =
+2-402 Stt
+ 8s
+0-049
55.
2-949 =
+2-671 8x
+ 8s
+0-174
56.
2-557 =
+2-675 &r
+ 8s
-0-218
From these we get —
or-
ott = -0-0154
fo = 2-816,
7T = 8-835 ± 0-035.
Rejecting the observations of Messrs. Stevens and Talmage (equations 17 and 39)
on the ground of their being " geometrical or apparent contacts," we have —
Residual.
1.
3-022 =
-2-142 8tt
+ 8s
+0-067
of 3 & 4.
3-120 =
-2-003 8?r
+ 8s
+0-023
7.
2-740 =
-2-003 8tt
+ 8s
-0-214
9.
2-977 =
-2-003 8?r
+ 8s
+0-023
10.
3-225 =
-1-903 8tt
+ 8s
+0-272
12.
2-999 =
-1-827 8tt
+ 8s
+0-047
13.
3-201 =
-1-827 8*-
+ 8s
+0-249
15.
3-159 =
-1-745 8x
+ 8s
+0-208
20.
2-664 =
-1-723 &r
+ 8s
-0-287
23.
2-427 =
-1-723 8tt
+ 8s
-0-524
29.
2-891 =
-1-723 8tt
+ 8s
-0-060
32.
2-382 =
-1-723 8a-
+ 8s
-0-569
35.
3-216 =
-1-723 &r
+ 8s
+0-265
38.
3-339 =
-0-749 8*-
+ 8s
+0-399
81
Residual.
And—
41.
2-941 =
+1-843 8a-
+ 8s
+0-033
42.
2-310 =
+2-195 8x
+ 8s
-0-598
43.
2-942 =
+2-196 8tt
+ 8s
+0-034
46.
3-643 =
+2-197 8x
+ 8s
+0-735
49.
3-049 =
+2-215 Stt
+ 8s
+0-143
52.
2-828 ==
+2-402 8tt
+ 8s
-0-078
55.
2-949 =
+2-671 8tt
+ 8s
+0-046
56.
2-557 =
+2-675 8x
= -o-oii
= 2-932,
+ 8s
-0-346
or-
77 = 8-839 ± 0-024.
If we reject the Cape Observatory observations altogether, the equations would be,
retaining the observations of Stevens and Talmage, —
Residual.
1.
3-022 =
-2-142 8*-
+ 8s
+0-104
of 3 & 4.
3-120 =
-2-003 8x
+ 8s
+0-206
7.
2-740 =
-2-003 8tt
+ 8s
-0-174
9.
2-977 =
-2-003 Stt
+ 8s
+0-063
10.
3-225 =
-1-903 fa
+ 8s
+0-314
12.
2-999 =
-1-827 fa
+ 8s
+0-090
13.
3-201 =
-1-827 &r
+ 8s
+0-292
15.
3-159 =
-1-745 fa
+ 8s
+0-253
17.
1-477 =
-1-741 fa
+ 8s
-1-429
38.
3-339 =
-0-749 fa
+ 8s
+0-463
39.
1-631 =
+1-843 fa
+ 8s
-1-168
41.
2-941 =
+2-195 fa
+ 8s
+0-153
42.
2-310 =
+2-196 fa
+ 8s
-0-478
43.
2-942 =
+2-197 fa
+ 8s
+0-154
46.
3-643 =
+2-215 fa
+ 8s
+0-855
49.
3-049 =
+2-402 8;r
+ 8s
+0-267
52.
2-828 =
+2-402 fa
+ 8s
+0-046
55.
2-949 =
+2-671 fa
+ 8s
+0-175
56.
2-557 =
87T :
8S :
+2-675 fa
= -6-030
= 2-854,
+ 8s
-0-217
Whence-
and —
7T = 8-820 ± 0-038.
With respect to such slight differences of illumination or "last appearances of
atmospheric tremor " as those which corresponded to the last recorded times near the
internal contact at the Royal Observatory, Cape of Good Hope, such phases do not
appear to have been generally seen, or at least generally regarded by the observers as
such " well-marked and persistent discontinuities in the illumination of the apparent
limb of the Sun near the point of contact" as could be recorded as times of "internal
contact." But Mr. Hall's observation at Kempshot Observatory, Jamaica, would,
however, appear to be an exception. Mr. Hall's last recorded time would give as wide
a separation of the limbs of Venus and the Sun as the last recorded times at the
Cape Observatory, and it appears from the observations themselves that at the
recorded time, 14h. 13m. 28s. ; any well-marked disturbance must have ceased.
L 4
82
Following Mr. Hall's instructions we have adopted the mean of the two last recorded
times, 14h. 13m. 10s. and 14h. 13m. 28s., as the time of internal contact ; but as the
corresponding phases at the Cape Observatory have been rejected in accordance with
Mr. Gill's wish, and as they should be in accordance with the instructions if they
refer to atmosphere tremor, and as 18s. is a very large interval, it appears desirable to
adopt the time 14h. 13m. 10s., at which the disturbance of the illumination is very
slight. This time cannot, however, be much too late, for at 14h. 13m. 3s., if Mr. Hall's
drawing is reliable, the contact was certainly far from over. Adopting therefore the
recorded time, 14h. 13m. 10s., for the internal contact at Kempshot Observatory, we
have the following 24 equations of condition : —
1,
3-022 =
-2-142 §tt
+ 8s
+0-169
Mean of 3 & 4.
3-120 =
-2-003 8tt
+ 8s
+0-271
7.
2-740 =
-2-003 3tt
+ 8s
-0-109
9.
2-977 =
-2-003 8*-
+ 8s
+0-128
10.
3-225 =
-1-903 Stt
+ 8s
+0-378
12.
2-999 =
-1-827 Stt
+ 8s
+0-154
13.
3-201 =
-1-827 8x
+ 8s
+0-358
15.
3-159 =
-1-745 &r
+ 8s
+0-316
17.
1-477 =
-1-741 Stt
+ 8s
-1-365
20.
2-664 =
-1-723 &r
+ 8s
-0-178
23.
2-427 =
-1-723 8tt
+ 8s
-0-415
29.
2-891 =
-1-723 Stt
+ 8s
+0-049
32.
2-382 =
-1-723 8tt
+ 8s
-0-460
35.
3-216 =
— 1-723 Ssr
+ 8s
+0-374
38.
3 339 =
-0-749 8*-
+ 8s
+0-523
39.
1 631 =
+1-843 §tt
+ 8s
-1-116
41.
2-941 =
+2-195 Stt
+ 8s
+0-204
42.
2-310 =
+2-196 8tt
+ 8s
-0-427
43.
2-942 =
+2-197 8x
+ 8s
+0-205
46.
3-203 =
+2-215 Stt
+ 8s
+0-466
49.
3-049 =
+2-402 for
+ 8s
+0-317
52.
2-828 =
+2-402 8tt
+ 8s
+0-096
55.
2-949 =
+2-671 8tt
+ 8s
+0-224
56.
2-557 =
+2-675 8tt
+ 8s
-0-168
From these we get—
&r = -0-027
85 = 2-796,
and —
77 = 8^23 ± 0'-034.
This result agrees very closely with the value ir = 8"-820, which we find when the
observations made at the Royal Observatory, Cape of Good Hope, are not employed
in the discussion. The close agreement between these results appears to show that
Mr. Grill's selection of the times which correspond to the " internal contact " at the
Royal Observatory, Cape of G-ood Hope, is satisfactory, and that the value —
7T = 8-823 ± 0-034 +0-065 Sa -0-0027 SA
may be accepted as the best result which the observations here discussed afford.
83
RESIDUAL EQUATIONS AND DISCUSSION OF EGRESS
OBSERVATIONS.
Egress. — Residual Errors from Times observed near the Internal Contact.
1. Barbados -
2.
3.
Mr. Talmage
Lieut. Thomson
- 8-122 =
- 7155 =
7-859 =
-2-571 &r + 3s
-2-571
-2-571
4. Bermuda
5.
6.
7.
Mr. Plummer -
Lieut. Neate
- 7-006 =
7-819 =
8-541 =
- [10-235] =
-2-566
-2-567
-2-567
-2-568*
8. Cambridge, U.S.A. -
Mr. Sawyer
- 6-761 =
-2-404
9. Ottawa, Canada
10.
Mr. Blake
- 5-533 =
7-556 =
-2-297
-2-297
11. Kingston, Canada
12.
Mr. Williamson
- 7-739 =
8-687 =
-2-295
-2-295
13. Jamaica
14.
Dr. Copeland
Capt. Mackinlay
- 8-119 =
- 7-888 =
-2-295
-2-295
15. Jamaica
Dr. Pearson
- 7-893 =
-2-295
16. Cobourg, Canada -
Prof. Bain
- 8-833 =
-2-264
17. Winnipeg, Canada
Mr. McLeod -
- 7-679 =
-1-823
18. Strait of Magellan -
19.
20.
Capt. Wharton -
- 6-161 =
7-769 =
8-713 =
+0-436
4-0-440
+0-443
21.
22.
Lieut. Havergal
- 6-689 =
7-398 =
+0-437
+0-440
23. Bidwill's, New Zealand
24.
25.
Mr. Marchant
- 7-078 =
7-964 =
8-535 =
+2-214
+2-212
+2-211
26. Wellington, New Zealand -
27.
28.
Mr. McKerrow -
- 7-169 =
7-646 =
7-965 =
+2-225
+2-225
+2-225
29.
30.
Mr. Adams
- 6-560 =
7-603 =
+2-225
+2-225
31.
32.
33.
Mr. T. King
- 5142 =
7-654 =
9-490 =
+2-230
+2-225
+2-222
34. Christchurch, New Zealand -
35.
Mr. Townsend -
- 7-387 =
8-165 =
+2-246
+2-244
A 22653.
* Approximation only.
M
84
36. Chnstchurch, New Zealand
37.
Mr. Kitson
- 6-589 = +2-248 &r + h
7-741 = 4-2-245
38. Burnham, New Zealand
39.
40.
Col. Tupman -
- 6-576 = +2-251
6-784 = +2-251
7-257 = +2-251
41.
42.
43.
Lieut. Coke
- 5-980 = +2-252
7-069 = +2-251
7-499 = +2-251
44. Nelson, New Zealand
Mr. Atkinson -
- 7-674 = +2-254
45. Dunedin, New Zealand
46.
47.
Mr. Beverly
- 7-270 = +2-255
7-634 = +2-255
8-621 = +2-253
48.
Mr. Gillies
•
- 7-020 = +2-256
49.
50.
Mr. Skey -
- 6-017 = +2-258
6-434 = +2-257
51 . New Plymouth, New Zealand
Mr. Humphries -
- 7-963 = +2-256
52.
Mr. O'Donahoo
- 7-791 = +2-256
53. Hobart, New Zealand
Mr. White
- 8-190 = +2-570
54. Melbourne - -
55.
Mr. Ellery
- 8-517 = +2-652
9-043 = +2-652
56.
Mr. Gilbert
- 8-605 = +2-652
57. Wentworth, New South
Wales.
Mr. Todd -
- 7-578 = +2-705
58.
9-831 = +2-704
The observations of internal contact at egress are somewhat difficult to deal with.
The observers at some stations have given only one time, while others have given two
and in some cases three times, and it is not easy to satisfactorily decide which of the
times, when there is more than one given, corresponds to those where only single
times are given ; the equations, therefore, have been solved by the method of least
squares in various ways and with the following results. The stations at which only
one time is given are included in each solution. Equations 29 and 30 have not been
included in the discussion, because the observations were made by projecting the Sun's
image on a screen, and therefore considered to be observed under somewhat different
conditions from the rest. The residual, however, agrees very closely with the mean
result.
Taking the first times given by the observers for contact, but, excluding " suspicion
of haze" or "mere atmospheric tremor disturbances/' we have the following
30 equations : —
Residual.
1.
8-122 =
-2-571 &r + 8s
+0-642
2.
7-155 =
-2-571 &r + 8s
-0-325
4.
7-006 =
-2-567 Stt + 8s
-0-474
8.
6-761 =
—2-404 &r + 8s
-0-715
9.
5-533 =
-2-297 &r' + 8s
-1-941
11.
7-739 =
-2-295 8tt + 8s
+0-265
13.
8-119 =
-2-295 8*- + 8s
+0-645
14.
7-888 =
-2-295 8tt + h
+0-414
15.
7-893 =
-2-295 8x + 8s
+0-419
16.
8-833 =
-2-264 8*- + 8s
+1-360
17.
7-679 =
-1-823 8*- + 8s
+0-216
85
Residual.
19. 7-769
21. 6-689
24. 7-964
26. 7-169
31. 5142
34. 7-387
36. 6-589
39. 6-784
42. 7-069
44. 7-674
45. 7-270
48. 7-020
51. 7-963
52. 7-791
50. 6-434
53. 8-190
54. 8-517
56. 8-605
57. 7-578
From which we obtain —
4-0-440 8tt
+0-440 8*-
+2-212 8*-
+2-225 for
+2-225 for
+2-246 for
+2-248 for
+2-251 Sz-
+2-251 for
+2-254 for
+2-255 for
+2-256 for
+2-256 for
+2-256 for
+2-257 for
+2-570 for
+2-652 for
+2-652 for
+2-705 for
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
8s
8s
8s
8s
8s
8s
8s
8s
8s
8s
8s
8s
8s
Ss
8s
8s
8s
8s
+0-357
-0-723
+0-592
-0-203
-2-230
+0-016
-0-782
-0-587
-0-302
+0-303
-0-101
-0-351
+0-592
+0-420
-0-937
+0-826
+1155
+ 1-243
+0-217
Therefore —
oV = -0-023
and 8s = +7422.
t =8-827 ±0-051.
Taking the last times recorded as internal contacts of any kind, we hav«
30 equations —
Residual.
1.
8-122 =
-2-571 for
+ 8s
+0-159
3.
7-859 =
-2-571 for
+ 8s
-0-104
6.
8-541 =
-2-568 8a-
+ 8s
+0-577
8.
6-761 =
-2-404 for
+ 8s
-1-208
10.
7-556 =
-2-297 for
+ 8s
-0-416
12.
8-687 =
-2-295 for
+ 8s
+0-715
13.
8-119 =
-2-295 for
+ 8s
+0-147
14.
7-888 =
-2-295 for
+ 8s
-0-084
15.
7-893 =
-2-295 for
+ 8s
-0-079
16.
8-833 =
-2-264 for
+ 8s
+0-860
17.
7-679 =
-1-823 for
+ 8s
-0-308
20.
8-713 =
+0-443 for
+ 8s
+0-653
22.
7-398 =
+0-440 for
+ 8s
-0-662
25.
8-535 =
+2-211 for
+ 8s
+0-418
28.
7-965 =
+2-225 for
+ 8s
-0-152
33.
9-490 =
+2-222 for
+ 8s
+1-373
35.
8-165 =
+2-244 for
+ 8s
+0-047
37.
7-741 =
+2-245 for
+ 8s
-0-377
40.
7-257 =
+2-251 for
+ OS
-0-861
43.
7-499 =
+2-251 for
+ 8s
-0-619
44.
7-674 =
+2-254 &r
+ 8s
-0-444
47.
8-621 =
+2-253 8*-
+ 8s
+0-503
48.
7-020 =
+2-256 for
+ 8s
-1-098
51.
7-963 =
+2-256 for
+ 8s
-0-155
52.
7-791 =
+2-256 for
+ 8s
-0-327
50.
6-434 =
+2-257 for
+ 8s
-1-684
53.
8-190 =
+2-570 for
+ 8s
+0-062
55.
9-043 =
+2-652 for
+ 8s
+0-912
56.
8-605 =
+2-652 for
+ 8s
+0-474
58.
9-831 =
+2-704 for
+ 8s
+1-698
SS6S3.
N
86
From which we find —
&r = +6-032
and h = +8-046.
Therefore —
7T =8-882 ±6-045.
The probable error upon this assumption is rather less than upon the first, and the
difference between the result is not greater than might be expected from the probable
error.
Solution on the assumption that the mean of the times recorded for the different
kind of contacts by some of the observers would, on the average, best agree with the
kind of contact to which the single time records refer.
Residual.
1. 8-122 = -2-571 3*- + 8s +0-386
2 & 3. 7-507 = -2-571 3*- + 3s -0-229
4, 5, & 6. 7-789 = -2-567 3*- + 3s +0-053
8. 6-761 = -2-404 3*- + 8s -0-976
9 & 10. 6-545 = -2-297 fa + 3s -1-192
11 & 12. 8-213 = -2-295 fa + 8s +0-476
13. 8-119 = -2-295 fa + 3s +0-382
14. 7-888 = -2-295 fa + 8s +0-151
15. 7-893 = -2-295 fa + 3s +0-156
16. 8-830 = -2-264 fa + 3s +1-096
17. 7-679 = -1-823 fa + 3s -0-060
19 & 20. 8-241 = +0-441 fa + 8s +0-491
22. 7-398 = +0-440 fa + 8s -0-352
24 & 25. 8-250 = +2-212 8*- + 8s +0-492
26, 27, & 28. 7-593 = +2-225 fa + 8s -0-165
31, 32, & 33. 7-429 = +2-226 3x + 3s -0-329
34 & 35. 7-776 = +2-245 fa + 8s +0-017
36 & 37. 7-165 = +2-247 8x + 8s -0-594
39 & 40. 7-021 = +2-251 fa + 8s -0-738
42 & 43. 7-284 = +2-251 fa + 3s -0-475
44. 7-674 = +2-254 fa + 3s -0-085
45, 46, & 47. 7-842 = +2-254 fa + 3s +0-083
48. 7-020 = +2-256 fa + 8s -0-739
50. 6-434 = +2-257 fa + 8s -1-325
51. 7-963 = +2-256 fa + 3s +0-204
52. 7-791 = +2-257 fa + 8s +0-032
• 53. 8-190 = +2-570 fa + 8s +0-431
54 & 55. 8-780 = +2-652 fa + 8s +1-020
56. 8-605 = +2-652 fa + 3s +0-845
57 & 58. 8-705 = +2-705 fa + 3s +0-944
From which we find-
Therefore —
fa = +0-005
and 8s = +7-748.
7T = 8-855 ±0-036.
The probable error is smaller than the probable error upon either of the first
assumptions, and the result, so far as these observations can fix it, would appear to lie
between —
*■ =8-827 ±6-061 -6-068 8« -0-0099 dA
and X =8-855 ±0-036 -0-068 8a -0-0099 dA.
87
Egress. — Residual Errors from times observed near the External Contact.
1. Barbados -
2.
3. Bermuda
4.
5.
6. Cambridge, U.S.A.
7. Jamaica
8.
9. Jamaica
10. Kingston, Canada
11. Ottawa, Canada
12.
13. Winnipeg, Canada
14. Strait of Magellan -
15. Bidwill's, New Zealand
16.
l7.*Wellington, New Zealand ' -
18.
19.
20. Christchurch, New Zealand
21.
22. Burnham, New Zealand
23.
24. Nelson, New Zealand
25.
26. D unedin, New Zealand
27.
28.
29. Auckland, New Zealand
30. Hobart
31. Melbourne -
32.
33. Wentworth, New South
Wales.
Mr. Talmage
Lieut. Thomson
Mr. Plummer
Lieut. Neate -
Mr. Sawyer
Dr. Copeland -
Capt. Mackinlay
Dr. Pearson
Mr. Williamson
Mr. Blake
Mr. McLeod
Capt. Wharton
Mr. Marchant -
Mr. Hewitt
Mr. Adams
Mr. McKerrow
Mr. King
Mr. Townsend
Mr. Kitson
Col. Tupman
Lieut. Coke
Mr. Atkinson
Mr. Beverly
Mr. Skey
Mr. Gillies
Capt. Heale
Mr. White
Mr. Ellery
Mr. Gilbert
Mr. Todd
- 6-902 = -2-641 fa + 8s
- 7-155 = -2-641
- 5-373 = -2-592
- 4-417 = -2-592
4-680 =■ -2-592
- 5-887 = -2-408
- 7-068 = -2-384
- 6-445 = —2-384
- 6-403 = -2-384
- 7-415 = —2-301
- 5-226 = —2-297
6-226 = -2-297
- 5-631 = -1-826
- 7-334 = +0-615
6-645 :
6-174 :
7-353 :
7-282 :
5-683 :
7-288 :
6-173 :
7-642 :
(9-418)=
6-219 =
7-104 -.
7-641 =
6-882 :
5-908 =
6-594 =
7-382 =
6-356 =
5-845 =
= +2-083
: 4-2-083
: 4-2-095
: 4-2-095
: +2-098
■ +2-117
: +2-120
+2-122
+2-119
+2-130
+2-128
+2-128
+2-130
+2-132
+2-131
+2-496
+2-595
+2-595
7-256 = +2-659
-Residual.
1.
6-902
=
-2-641 fa + 8s
+0-615
2.
7155
=
-2-641 8*- + 8s
+0-868
3.
5-373
=
-2-592 fa + 8s
-0-919
&5.
4-548 (mean) =
-2-592 fa + 8s
-1-744
6.
5-887
=
-2-408 fa + 8s
-0-422
7.
7-068
=
-2-384 8jt + 8s
+0-757
8.
6-445
=Z
-2-384 fa + 8s
+0-134
9.
6-403
zz=
-2-384 fa + Bs
+0-092
10.
7-415
=
-2-301 fa + 8s
+1-096
12.
6-226
zzz
-2-297 fa + 8s
-0-093
13.
5-631
zzz
-1-826 fa + Ss
-0-759
* Not used ; image projected.
88
Kesidual.
14.
7334
=
+0-615 for
+ 6S
+0-746
15.
6-645
^n
4-2-083 for
+ 6S
-0-078
16.
6-174
^r
4-2-083 for
+ 8s
-0-549
18.
7-282
:^
4-2-095 for
+ 6s
+0-558
19.
5-683
•^
4-2-098 for
+ 8s
-1-041
20.
7-288
=
4-2-117 for
+ 8s
+0-561
21.
6-173
4-2-120 for
+ 8s
-0-554
22.
7-642
=
4-2-122 for
4- 8s
+0-915
24 & 25.
6-661 (mean) =
4-2-129 for
+ 6s
-0-066
26.
7-641
r^:
+2128 8jt
+ 8s
+0-914
27.
6-882
—
+2-130 for
+ 8s
+0-154
28.
5-908
=
+2-132 8tt
+ 8s
-0-820
29.
6-594
^
+2-131 for
+ 8s
-0-134
30.
7-382
—
+2-496 8*-
+ 8s
+0-621
31.
6-356
=
+2-595 8t
+ 8s
-0-414
32.
5-845
=
+2-595 for
+ 8s
-0-925
33.
7-256
=
+2-659 &r
+ 8s
+0-479
Which, gives—
for =
: +6-092
and 8s =
: +6-531.
Therefore —
7T =8-942 ±0-047.
E. J. Stone.
LONDON : Printed by Eyre and Spottiswoodi,
Printers to the Queen's most Excellent Majesty.
For Her Majesty's Stationery Office.
[4764.— 500.— 6/87.]
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