•; t
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TRONOM J L SOCIETY
^/^\^
PRESENTED
*i^-'
BY ORDER OF THE
RIGHT HONORABLE THE GOVERNOR
IN COUNCIL,
To
.A.T
Ex Xibris
i
OK'
LIBRARY
OF THE
ASTRC MOM CAL SOCJETY
°
GIFT OF
ASTROITGL1ICAL SOCIETY
IACIPIC
OF THE
ASTRONOMY DEFT.
LIBRARY
OF T! IE
ASTRO NO fV! CAL SO<
TELEGRAPHIC DETERMINATIONS
OP THE
DIFFERENCE OF LONGITUDE
BETWEEN
KARACHI, AVANASHI, ROORKEE, PONDICHERRY, COLOMBO, JAFFNA,
WlUDDAPUR AND SINGAPORE,
AND THE
GOVERNMENT OBSERVATORY, MADRAS,
BY
NORMAN R. POGSON, C.I.E.,
u
F.R.A.S. AND F.M.U.
Government Astronomer at Madras.
MADRAS:
PRINTED AT THE LAWRENCE ASYLUM PRESS, BY W. H. MOORE.
1884.
*&*
ASTRONOMY
CONTENTS.
Page.
Introductory Remarks ... ... ... ... 1
Pondicherry ... ... ... ... ... ... 4
Singapore ... ... ... ... ... ... ... n
Avanashi ... ... ... ... ... 25
•
Jaffna ... ... ... ... ... ... ... 30
Colombo ... ... • ... ... ... ... 38
Karachi ... ... ... ... ... ... ... 47
Muddapur ... ... ... ... ... ... 55
Eoorkee ... ... ... ... ... ... ... 66
Summary of Final Results and concluding Remarks ... ... 80
701303
TELEGRAPHIC LONGITUDE DETERMINATIONS IN INDIA.
The telegraphic longitude determinations, details of which are now
given in a collected form, were none of them taken under perfectly
satisfactory conditions, such as were available to the officers of the Great
Trigonometrical Survey in their far more elaborate series of measurements
made a few years later.
The impossibility of interchanging observers or of settling their
relative personal equations, and the want of proper chronographs, left in
each case a small uncertainty, insignificant in comparison of the best values
obtainable by any other method than that of telegraphic signals, but
nevertheless existent and incapable of elimination from the results.
So long since as the end of 1861, I proposed to the Government of
Madras an extensive series of telegraphic longitude measurements, and
in the " Proceedings of the Madras Government, llth January, 1862,"
I was called upon to report what arrangements would be required to carry
out my views in determining the relative longitudes of Bombay, Beypore
and Trevandrum on the West Coast, and of Calcutta, Cocanada and Nega-
patam on the East, from the Madras Observatory. In my report, submit-
ted on the 30th of the same month, I pointed out the desirability of such
determinations, the very moderate outlay involved, and the processes which
then appeared to me most suitable for the purpose. On the 22nd Septem-
ber 1862, I submitted further specifications of the instruments required for
the purpose, and was most desirous of doing what has since been so ably
accomplished by the officers of the Great Trigonometrical Survey, but the
matter was allowed to drop and my plans fell through in consequence.
The need of a good cylinder chronograph for other purposes, especially
for investigation of the solar parallax by means of observations of the
planet Mars in opposition, for which Madras Observatory is above all
2 TELEGBAPHIC LONGITUDE DETERMINATIONS IN INDIA.
others the most favorably situated in the world, was often urged, but to
this day nothing of the kind has been supplied, except a French tape
recorder, sent out in November 1874, for the Transit of Venus due in the
following month ; — a mere toy which no astronomer would care to possess
and which has never been of the slightest use since its arrival. The chro-
nographs now constructed by leading American and British makers are as
near perfection as can be desired, and enable inexperienced observers to
make records, equal, if not superior to those obtainable by long practised
observatory assistants without such aid ; while in cases in which numerous
times have to be noted, in more rapid succession than any one could
possibly accomplish by the old eye and ear method, they are simply indis-
pensable. American chronographs seem to me preferable for their greater
simplicity, having only one pen or pencil for both clock seconds and
observer's records, instead of two, separately marking side by side ; and
also in their being worked by a portable chronometer, just as readily as
by a fixed astronomical clock.
So far as the Madras portion of the eight following longitude deter-
minations is concerned, the star observations for local time have been
reduced, by application of the known personal equation for each transit
observer, to my own standard ; but never having even seen the gentlemen
with whom I had to co-operate in five cases, and having had no oppor-
tunity of comparing our habits of observation in any, except that of
Avanashi, the small difference due to personal equation between myself and
the operator at the other end remains in each case indeterminate.
The probable errors for the mean results of transit observations and
telegraphic signals on each night have been deduced by Professor C. H. F.
Peters' convenient formula (disregarding algebraic signs and squaring) by
multiplying each of the means of the Residual Errors by ^^ ; and these, com-
bined in the usual way, show, for the final results for each place, the small
amounts of uncertainty attributable to the time found by the star transits
and to the exchanges of telegraphic signals, over and above which there
will still remain the unknown personal equations and the errors of coin-
cidence comparisons whenever a different time-piece was used for finding
local time and for noting the signals. The latter cannot exceed two or
three hundredths at the most, but the former may amount to a sensible
fraction, of a second. In no instance however is it likely that any result
MADEAS FEOM GREENWICH. 3
will be so mucli as a second of time in error, and for the purposes for
which seven of these determinations were made, viz., for the Total Solar
Eclipse of December 1871 and the Venus Transit in December 1874, no
such accuracy was required.
The longitude or difference of time between Madras and Greenwich was
first approximately determined by Mr. John Goldingham, by means of
eclipses of Jupiter's satellites, between 1787 and 1815, and was com-
municated by him to the Koyal Society as oh. 21m. 9 '4s. Additional
observations of the same nature, taken between 1817 and 1826, confirm-
ed this result, giving a mean value only 0'4s. less but about 10 seconds
too great as now determined.
The next astronomer, Mr T. G. Taylor, realizing the now familiar
fact, that time found by eclipses of Jupiter's satellites is extremely uncertain,
differing with the telescopic aperture and power employed, as well as with
the conditions of the atmosphere, twilight, moonlight, and most of all
perhaps with the observer's health and visual perception, had recourse to
the far better method of moon culminators, and from a few observations in
1831 obtained a smaller value, viz., 5/L 21m. 3'77s. which was adopted in
the Nautical Almanac list from 1835 to 1861. A much closer approxima-
tion was, subsequently arrived at by Mr. Taylor from the discussion
of lunar observations between 1831 and 1844, which gave 5h. 20m. 5 7' 2s. ;
but though published in 1845 it was overlooked and not admitted into the
Nautical Almanac list until 1862.
The adopted value 5h. 20m. 59'4s. given in the Nautical Almanac
since 1882, is a combination result, in which the telegraphic longitude
of Suez, by members of the Transit of Venus Expedition in 1874, was
combined with others, between Suez, Aden, Bombay and Madras, made by
the officers of the Great Trigonometrical Survey of India in 1876 and
1877.
Should a final trial by means of direct signals between the Greenwich
and Madras Transit Clocks ever be accomplished, verification rather than
correction will probably be all that can be expected from the undertaking.
4 TELEGEAPHIO LONGITUDE DETERMINATIONS IN INDIA.
PONDICHERRY.
The first telegraphic determination of the difference of longitude
between Madras and any other station in India was made conjointly by
myself at Madras and by Mons. G. Fleuriais at Pondicherry. The reasons
for this undertaking are best given in M. Fleuriais' own words, in the
following letter addressed to me by that able and distinguished officer.
PONDICHERRY, 5th Decembre 1869.
MONSIEUR LE DIRECTEUR,
En Avril 1867, Jai ete charge par le bureau des longitudes de France,
d'une Mission Scientifique ayant pour objet la recherche, par la methode
astronomique dite des Culminations lunaires, des longitudes absolute
d'un certain nombre de points du globe.
Mes instructions m'enjoignaient ;
1°, d'observer a Paris, pendant 3 mois au moins, avec les instruments
que j'emporterais en voyage, afin de m'habituer au maniement de ces
derniers et de determiner tres exactement mon equation personnelle.
2°, D'accomplir un tour du monde complet en sejournant sur les
Points suivants : Montevideo, Sandy Point (de N. de Magellan), Valparaiso,
Callao, Panama, Honolulu, Yokohama, Shanghai, Pondicherry.
3°, De revenir a Paris et d'y determiner de nouveau la valeur de mon
equation personnelle.
Sur les 9 stations designees, 8 sont achevees. Arrive a Pondicherry
le 27 Novembre, je termine actuellement le montage d'une Lunette meri-
dienne qui me permettra de commencer, des la reapparition de la Lune, les
observations qui m'incombent.
Comme vous 1'avez, deja compris, le but que se propose le Bureau des
Longitudes est l'obtention d'un certain nombre de Meridiem fondamentaux
qui poussaient ulterieurement servir a la verification des points interme-
diaires.
PONDICHERBY. 5
Partout ou je 1'ai pu, J'ai cherche a relier les villes environnants au
point ou je sejournai moi-meme, soit au moyen du telegraphe electrique,
soit par traversee chronometriques.
Les resultats que je vais m'efforcer d'obtenir ici, n'auront qu'un bien
mediocre interet s'ils ne s'adressent qu'a Pondicherry.
II n'en serait point de meme si cette derniere ville pouvait etre reliee
aux grands Centres des Indes.
Les differences des meridiens de Bombay, Calcutta, Madras ont, je
crois deja ete obtenues au moyen du telegraphe. Mais aucune operation
de ce genre n'a encore en lieu sur Pondicherry.
Votre presence a Madras, jointe a 1'existence d'une ligne telegraphique
directe (ou pouvant etre etablie en communication directe) entre ce point
et Pondicherry, m'a fait penser que vous vous occupeiz avec plaisir de la
determination des differences d'heures des deux villes en question.
Une semblable operation, si j'en juge par 1'analogue que j'ai du faire
en 1868 entre Santiago et Valparaiso, ne demanderait guere que le like
usage du telegraphe pendant 2 beures au plus ; mais auparavant, il faudrait
etablir, par correspondance, des conventions simples et nettes, faire quelques
demarches officielles, enfin convenir d'un jour et d'une heure donnee pour
laquelle il serait facile a vous et a moi d'obtenir le reglage parfait de un ou
plusieurs chronometres.
Dans cette circonstance tout depend de votre volonte. Je n'ai done
voulu ni parler de ce projet a Monsieur le Gouverneur ni entrer dans
aucun detail d' execution. J'attends pour cela votre reponse, qui, si elle est
favorable comme je 1'espere, exciterait un vif sentiment de reconnaissance
chez ceux dont je ne suis que le mandataire.
Veuillez agreer Monsieur le directeur, &c., &c.
(Signed) Gr. FLEUEIAIS,
Lieutenant de Vaisseau, en Mission Scientifique d Pondicherry (gouvernement.)
It is needless to state that the opportunity thus afforded me of co-
operating with Monsieur Fleuriais was most willingly complied with, and
the few requisite preliminary preparations being made, the work was success-
6 TELEGRAPHIC LONGITUDE DETERMINATIONS IN INDIA.
fully carried out on January 14th, 1870. The use of the telegraph wire
was readily granted us by the Government Telegraph Department, and the
local officers in charge rendered us the most cordial aid at each end of the
line. My thanks were especially due on this occasion to G. Barclay, Esq.,
Assistant Superintendent at Madras.
The local sidereal time at Madras being found by ten good transit
observations, a mean time chronometer was compared with the transit
clock by means of coincident beats and was then carefully transported to
the Government Telegraph Office about three miles distant, where the
signals, consisting of sharp taps on the Morse instrument employed for
the usual telegraphic messages, were both given and recorded by me per-
sonally, in preference to noting those sent by a signaller, a precaution
which no doubt renders the results far more certain than when the latter
course is adopted. The mean time chronometer was then taken back to
the Observatory and again compared with the Transit clock, its rate being
determined solely from the comparisons made before and after the opera-
tions.
At Pondicherry precisely the same course was followed by Mons.
Fleuriais, his local sidereal time being also found by ten clock stars, using a
sidereal chronometer by Breguet, and for comparison and signalling a mean
time one by Leroy. The time determinations, comparisons and signals are
given in the following tables, but it is to be regretted that Mons . Fleuriais
only sent me five out of the thirty-eight signals transmitted to him, vie.,
the first and last of each set, and one intermediate one which he con-
sidered preferable' to all others as being an absolute coincidence. No
retardation, either of current or instruments, was perceptible on this
occasion.
In publishing telegraphic longitude determinations it is usual to
suppress the individual signals and to give only mean results, but I have
exhibited all in detail, so as to render the admission of a single erroneous
step impossible throughout.
The special geographical points referred to in this determination are,
the centres of the Transit Circle in the Madras Observatory and of the Light-
house at Pondicherry. The difference of time between Mons. Fleuriais*
temporary observatory and the Light-house was given by him 0*56 second,
as obtained by triangulation with a theodolite.
TIME DETERMINATIONS AND CHRONOMETER COMPARISONS-
MADRAS,
PONDICHEERY.
Local Sidereal Time Determinations, 1870, January 14.
Name of
Star.
Transit
Clock.
Sidereal
Correction.
Residual
Errors.
Name of
Star.
Chronometer
Bregnet, 889.
Sidereal
Correction.
Residual
Errors.
8 Arietis
Alcyone
h. in.
3 5
3 40
s.
- 34-22
- 34-32
s.
+ 0-01
- 0-06
a Ceti
h. m.
2 57
3 5
TO. S.
- 1 15-13
- 1 15-24
s.
+ 0-11
o-oo
8 Arietis ...
o Eridani
4 6
4 22
4 29
- 34-36
- 34-33
- 34-28
- 0-08
- 0'04
+ 0-01
Alcyone
7' Eridani ...
e Can. Maj...
3 41
3 55
6 55
- 1 15-27
- 1 15-31
- 1 15-28
-0-01
- 0-04
+ 0-08
Aldebaran
yGeminornm.
6 31
- 34-30
+ 0-08
TJ Can. Maj...
6 59
- 1 15-34
+ 0-02
e Can. Maj....
6 54
- 34-37
+ 0-03
8 Geminorum
7 14
- 1 15-31
+ 0-05
S Geminorum
Procyon
7 13
7 33
7 38
- 34-29
- 34-43
- 34-45
+ 0-12
. o-oo
- 0-02
£ Can. Min...
Castor
7 21
7 28
7 34
- 1 15-39
- 1 15-42
- 1 15-47
- 0-02
-0-05
- 0 10
Pollux
Procyon
Means
5 33
- 34-34
0-045
Means
5 43
- 1 15-32
0-048
Adopted dai
ly change
- 1-07
Adopted da
-0-70
NOTE. — The adopted daily change duly allowed for in finding the Residual Errors.
Comparisons of Chronometers used for Signalling.
Transit
Clock.
Sidereal
Correction.
Chronometer
Dent 1668.
Mean Time
Correction.
Chronometer
Breguet 889.
Sidereal
Correction.
Chronometer
Leroy 227.
Mean Time
Correction.
H vn s.
s.
h. m. s.
s.
h. m. s.
TO. S.
4 26 0
- 34-29
8 57 54-0
-10-54
5 53 50
- 1 15-31
10 26 13-5
- 1 35-53
8 6 12
- 34-45
12 87 29-5
- 10-28
7 57 10
- 1 15-38
12 29 13-5
- 1 35-81
TELEGRAPHIC LONGITUDE DETERMINATIONS IN INDIA.
Madras and Pondicherry Time Corrections, 1870, January 14.
At Sh. 58m. by Mr. Pogsoii's Chronometer Dent 1868, it was 10-54 seconds fast of Madras Mean Time
with an adopted daily rate of 1'70 seconds losing.
At 10ft. 26m. by M. Pleuriais' Chronometer Leroy 227, it was Im. 35'53s. fast of Poudicherry Mean
Time, with an adopted daily rate of 3'27 seconds gaining.
Hence at 10ft. 25m. by Chronometer Dent 1668, the relative correction was Im. 25-09s., and its change
-j- 0'00345 second per minute.
Telegraphic Signals from Madras to Pondicherry.
Madras
Signals.
Pondicherry
Records.
Difference.
Mad.— Pon.
Relative
Correction.
Pondicherry
West.
Residual
Errors.
ft. m. s.
ft. m. s.
s.
m. s.
TO. s.
s.
10 0 30
10 0 15-75
14-25
1 25-01
1 39-26
-o-oi
10 0
9 45-75
14-25
1 25-04
1 39-29
+ 0-02
11 30
11 15-80
14-20
1 25-04
1 3924
- 0-03
18 30
18 15-80
14-20
1 25-07
1 39-27
o-oo
10 20 0
10 19 45-80
14-20
I 25-07
1 39-27
o-oo
10 12 6-00
10 11 51-78
1422
1 25-05
1 39-27
0-012
Telegraphic Signals from Pondicherry to Madras.
Madras
Records.
Pondicherry
Signals.
Difference
Mad. — Pon.
Relative
Correction.
Pondicherry
West.
Residual
Errors.
ft. TO. S.
ft. m. s.
s.
m. s.
m, s.
s.
10 30 29-3
10 30 15
14-3
1 2511
1 39-41
+ 0-14
30 44-2
30 30
14-2
1 25-11
1 39-31
+ 0-04
31 14-2
31 0
14-2
1 25-11
1 39-31
+ 0-04
31 29-3
31 15
14-3
1 2511
1 39-41
+ 0-14
10 31 44-3
10 31 30
14-3
1 25-11
1 39-41
+ 0-14
TELEGRAPHIC SIGNALS.
Telegraphic Signals from Pondicherry to Madras.
Madras.
Eecorda.
Pondicherry
Signals.
Difference
Mad. — Pon.
Eelative
Correction.
Pondicherry
West.
Residual
Errors.
h. m. s.
10 32 14-2
h. tn. s.
10 32 0
s.
14-2
m. s.
1 25-11
m. s.
1 39-31
s.
+ 0-04
32 29-2
32 15
14'2
1 25-12
1 39-32
+ 0-05
32 44-1
32 30
14-1
1 25-12
1 39-22
- 0-05
33 14-2
33 0
14-2
1 25-12
1 39-32
+ 0-05
33 29-2
33 15
14'2
1 25-12
1 39-32
-f 0 05
33 44-2
33 30
14-2
1 25-12
1 39-32
+ 0-05
34 14-1
34 0
14-1
1 25-12
1 39-22
-0-05
34 29-2
34 15
14-2
1 25-12
1 39-32
+ 0-05
34 44-3
34 30
143
1 25-12
1 39-42
+ 0-15
35 14-2
35 0
14'2
1 25-13
1 39-33
+ 0-06
35 29-0
35 15
14-0
1 25-13
1 39-13
-0-14
35 44-2
35 30
14-2
1 25-13
1 39-33
+ 0-OG
36 14-1
36 0
14-1
1 25-13
1 39-23
-0-04
36 44-2
36 30
14-2
1 25-13
1 39-33
+ 0-06
37 14-1
37 0
14-1
1 25-13
1 39-23
-0-04
37 29-2
37 15
14'2
1 25-13
1 3933
+ 0-06
37 44-2
37 30
14'2
1 25-13
1 39-33
+ 0-06
38 14-0
38 0
14-0
1 25-14
1 39-14
-0-13
38 44-1
38 30
14-1
1 25-14
1 3924
-0-03
39 14-2
39 0
14-2
1 25-14
1 39-34
+ 0-07
39 29-1
39 15
14-1
1 25-14
1 39-24
-0-03
39 44-1
39 30
14-1
1 25-14
1 39-24
-0-03
41 29-1
41 15
14-1
1 25-15
1 39-25
-0-02
41 44-0
41 30
14-0
1 25-15
1 3915
-012
42 14-2
42 0
14-2
1 25-15
1 39-35
+ 0-08
42 29-0
42 15
14-0
1 25-15
1 39-15
-0-12
42 44-2
42 30
14-2
1 25-15
1 39-35
+ 0-08
43 14-1
43 0
14-1
1 25-15
1 39-25
-0-02
43 29-0
43 15
14-0
1 25-15
1 3915
-0-12
43 44-1
43 30
14-1
1 25-15
1 39-25
- 0-02
44 14'1
44 0
14-1
1 25-16
1 39-26
-o-oi
44 29-2
44 15
14-2
1 25-16
1 39-36
+ 0-09
44 44-0
44 30
14-0
1 25-16
1 3916
- 0-11
45 140
45 0
14-0
1 25-16
1 39-16
- 0-11
45 44-0
45 30
14-0
1 25-16
1 39-16
- 0-11
46 14-2
46 0
14-2
1 25-16
1 3936
+ 0-09
46 29-0
46 15
14-0
1 2516
1 39-16
-0-11
46 44-3
46 30
14-3
1 25-16
1 39-46
+ 0-19
47 14-0
47 0
14-0
1 25-17
1 39-17
- 010
10 47 29-1
10 47 15
14-1
1 25-17
1 39-27
o-oo
3
10
TBLEGEAP.HIC LONGITUDE DETERMINATIONS IN INDIA.
Telegraphic Signals from Pondicherry to Madras.
Madras
Records.
Pondicherry
Signals.
Difference
Mad. — Pon.
Eelative
Correction.
Pondicherry
West.
Eesidual
Errors.
h. m, s.
h. in. s.
g.
tn. s.
TO. S.
s.
10 47 44'0
10 47 30
14-0
1 2517
1 3917
-010
48 14-1
48 0
141
1 25-17
1 39-27
o-oo
48 29-0
48 15
14-0
1 25-17
1 39-17
- 010
48 44-2
48 30
14-2
1 25-17
1 39-37
+ 0-10
49 14-0
49 0
14-0
1 2517
1 39-17
- 010
49 29-0
49 15
14-0
1 25-17
1 39-17
- 010
49 44-0
49 30
14-0
1 2518
1 39-18
-009
50 14-0
50 0
14-0
1 25-18
1 3918
- 0-09
50 291
50 15
14-1
1 2518
1 39-28
+ 0-01
10 50 44-2
10 50 30
14-2
1 2518
1 39-38
+ 011
10 40 40-58
10 40 26-45
14-13
1 2514
1 39-27
0075*
Hence by fire signals to and fifty-five from Pondicherry, Monsieur Fleuriais' temporary Observatory was
1m. 39-27s. West of Madras.
Final Results.
h. m. s.
Madras Observatory East of Greenwich ... 5 20 59 '40
Pondicherry Observing Station West of Madras. — 1 39 '2 7
Pondicherry Light-house East of Observing Station + 0'56
Pondicherry Light-house East of Greenwich ...
Probable Error of result, exclusive of Personal
Equation
5 19 20-69
± 0-020
SINGAPOEE. 11
SINGAPORE.
The second application for a telegraphic longitude determination was
made to me by Professor J. A. C. Oudemans, Surveyor General of Java, in
November, 1870, and was one of the greatest interest, from its importance
as a link in the telegraphic line from Greenwich to Australia. Professor
Oudemans had already connected Batavia, the capital of Dutch India, with
Singapore, and the cable between the latter place and Madras having been
very recently laid, he hoped to have been granted its use early in 1871.
The permission came too late, and Professor Oudemans had to return to
Batavia without carrying out his plans. The cordial offers of co-operation
on the part of the officials of the British India Extension Telegraph Com-
pany, without which success would have been improbable, induced him to
make a further representation of the importance of the work to his Govern-
ment ; and this meeting with favorable consideration, I had great pleasure
in lending willing aid to the scheme. Telegraphic correspondence, most
freely and liberally granted by the Company, enabled us speedily to arrange
all details, and the work was accomplished on the four nights, July 24th,
25th, 26th and 28th, 1871.
Owing to unfortunate interruptions and other causes it is to be
regretted that no steps towards the calculation of the results were possible
until January, 1876, when I first received Professor Oudemans' time correc-
tions and records of signals. The individual clock corrections not having
been furnished me, I can only express my hope and belief, that Professor
Oudemans has modestly underrated the accuracy of his observations for
time and I cannot acquiesce in the rejection of any one of the four results
obtained. In his abstract, published in the " Astronomisches Nachrichten
No. 2486" he has used only the mean of the signals exchanged on the
first and third nights, whereas, if I had rejected any, it would have been
those of the third night, in consequence of a too large change in the cor-
rection of the mean time chronometer I used for giving and noting the
signals. The work on the last night was, on my side, probably the best of
the four, and in any case I consider none so doubtful as to be unworthy of
acceptance.
There is a small difference between my clock corrections now given and
those furnished to Professor Oudemans, arising from change in the adopted
personal equations of my assistants, which were then only provisionally
assumed, but have since been finally settled, so far as can be done, from all
the observations made for the purpose. Altogether, my final longitude of
12 TELEGRAPHIC LONGITUDE DETERMINATIONS IN INDIA.
Singapore is 0*25 second more than Professor Oudemans deduced, and 0*54
less than has since been found by Lieut. Commander C. H. Davis and Lieut.
J. A. Morris of the U. S, Navy, in January, 1882. The exquisite instru-
ments I had the pleasure of seeing employed here by my esteemed American
friends Messrs. Davis and Lemley, as well as the skilful way in which they
were handled, were the realization of what I had hoped for when I first
made my own proposals to Government for longitude determinations upon
my arrival in India. Perfection of accurate simplicity, eschewing all
affectation of needless refinement, seems to be the distinguishing charac-
teristic of American scientific instruments and researches in general, and
of such nature were the appliances and methods used upon this occasion.
The operations for determining the difference of longitude between
Madras and Singapore require little explanation beyond what is given in the
following tabular statements. • The points referred to were, the Madras
Transit Circle and the Singapore Government Flagstaff. As in the case of
Pondicherry, a mean time chronometer was compared with the Madras
Transit Clock and conveyed to and from the Office of the British Indian
Extension Telegraph Company, about four miles from the Observatory.
An unsatisfactory change in the chronometer rate, in the interval between
the before and after comparisons, occurred on July 26th, but the result does
not appear to have 'been much affected thereby. At Singapore, Professor
Oudemans used a mean time chronometer for the signals on the first night,
but on the other three the sidereal chronometer with which his transits
were observed. The- signal taps were given at each end by ourselves, but
the records are far more difficult by cable than on a land line ; the lateral
motion of a small flash of light, reflected from a tiny mirror on a screen,
appearing to an observer far less satisfactory than the sharp tap of a Morse
instrument.
The scheme agreed upon was, twelve signals at fifteen seconds interval
from Madras ; the same from Singapore, and both operations repeated ; but
I see no advantage in such interrupted records and prefer to treat all sent
the same way as one series each night. One or two signals were occasion-
ally missed, but each result was so similar in quality, that weights on that
account were unnecessary.
The Mean Retardation, which is of course due partly to actual wave
retardation through the cable and partly to inertia in the instruments at
each end, called by the American observers " Wave and armature time,"
was smaller in our case than in theirs, arising no doubt from the use of a
greater battery power in 1871 than in 1882.
LOCAL TIME DETERMINATIONS.
Local Sidereal and Mean Time- Determinations.
13
MADRAS.
SINGAPORE.
Transit
Sidereal
Residual.
All Time Corrections reduced to the position
Star.
Clock.
Correction.
Errors.
of the Government Flagstaff.
1871, July 24.
1871, July 24.
h. TO.
s.
s.
Antares
16 21
+ 58-44
o-oo
£ Herculis...-
16 35
+ 58-55
+ 0-11
Time determinations made by means of an excellent
Universal Instrument by Repsold, and a Mean
K Ophinchi....
16 • 51
4- 58-38
- 0-06
Time Chronometer, Schmidt 325.
o Herculis ....
17 8
4- 58'51
4-0-08
Two zenith distances of Arcturus observed in one
position and one in another. Also four zenith
9 Ophinchi....
17 13
+ 58'35
-0-08
distances each of Altair and £ Ceti.
a Ophinchi....
17 28
4- 58*39
- 0-03
/x Herculis ....
17 40
4-58-46
4-0-04
Star. Chronometer. Correction.
/j.1 Sagittarii.
18 5
4- 58-30
-o-ii
h. m. tn. s.
f Aquilae
18 59
4- 58-38
- 0-02
Arcturus 88 2 21*065
8 Aquilae
19 18
4- 58-39
o-oo
Altair 13 40 2 20-47
h- Sagittarii..
19 28
+ 58*32
-0-07
0 Ceti 14 5 —2 20'67
Altair
19 44
4- 53-52
4-0-14
Adopted daily change ... ... ... 4-2-07
/3 Aquilae
19 48
4- 58-41
4- 0-03 •
o2 Capricorni
20 10
4- 53-37
o-oo
18 12
+ 58*41
0-055
Probable erro
r of mean c
jrrection
± 0-013
Adopted daily change ... ... ... — 0'45
1871, July 25.
1871, July 25.
h* Sagittarii.
19 28
4- 58*17
+ 0-23
y Aquilae
19 39
4- 57*89
-0-04
Sidereal Time found with a new portable Transit
Instrument by Wenckebach, the eyepiece of which
19 44
+ 57'97
+ 0-04
was at one extremity of the axis. The Chronome-
ter used was Hohwn 394. No details of the ob-
/3 Aquilae
19 48
• 4- 57-91
- 0*02
servations communicated, but the estimated un-
certainty of the result given as 0'15 second.
p Capricorni.
20 21
4- 57*81
-o-ii
32Vulpeculae
20 48
+ 57*80
- 0-11
•
14
TELEGRAPHIC LONGITUDE DETERMINATIONS IN INDIA.
MADRAS.
SINGAPORE.
Star.
Transit
Clock.
Sidereal
Correction.
Residual
Errors.
All Time Corrections reduced to the position
of the Government Flagstaff.
1871, July 25 — continued.
1871, July 25 — continued.
( Cvffni...,
h, in.
21 7
21 24
. 21 37
s.
+ 57-94
+ 57-87
+ 57-89
s.
+ 0-03
-0-03
- o-oi
h. TO. s.
At 17 30 the correction was -j- 24'56
£ Aquarii
Means
20 26
r of mean c
+ 57-92
orrection ...
0069
±0-021
*
Probable erro
Adopted daily change ... ... ... — 0*42
1871, July 26.
1871, July 26.
K Ophiuchi....
16 51
+ 57-55
-0-03
a Herculis
a Ophiuchi....
17 8
17 28
+ 57-62
+ 57-56
H-0-04
-o-oi
Sidereal Time found with the portable Transit
Instrument and Chronometer Hohwn 394, as
follows : —
M Herculis
17 40
+ 57-67
+ 0-10
/^Sagittarii ...
£ Aquilse
18 5
18 59
19 11
+ 57-55
+ 57-51
+ 57-49
- 001
- 0-04
- 0-06
s.
By six stars eyepiece East + 28'085
By five stars eyepiece West + 28-238
By six stars eyepiece East + 28'259
t*. Aquilse
8 Aquilae
y Aquilse
Altair
19 18
19 39
19 44
+ 57-60
+ 57-48
+ 57-58
+ 0-05
- 0-06
+ 0-04
h. m. s.
Hence at 18 0 the correction was +27-04
Adopted daily change •}- 2'28
18 24
r of mean c
+ 57-56
orrection
0-044
±0-012
Probable erro
Adopted daily change — 0'36
LOCAL TIME DETERMINATIONS AND CHRONOMETER COMPARISONS.
15
MADRAS.
SINGAPORE.
Star.
Transit
Clock.
Sidereal
Corrections.
Residual
Errors.
All Time Corrections reduced to the position
of the Government Flagstaff.
1871, July 28.
1871, July 28.
h. m.
s.
s.
<* Herculis....
17 40
18 32
18 59
19 11
+ 56-73
-f 56-80
+ 56-72
+ 56-77
-0-06
+ 0-03
- 0-05
4-0-01
Sidereal Time found with the
Instrument and Chronometer
follows : —
By five stars eyepiece East
portable Transit
Hohwn 394 as
s.
+ 33-904
£ Aquilce
w Aquiloe
8 Aquiloe
19 18
+ 5670
-0-06
By ten stars eyepiece West
+ 33-514
y Aquilce
Altair
19 39
19 44
19 48
20 10
20 21
+ 56-79
+ 56-83
+ 56-74
+ 56-77
+ 56-73
+ 0-04
+ 0-08
- o-oi
+ 0-02
-o-oi
By seven stars eyepiece East
h. m.
+ 33-318
s.
. .. +32-40
/3 Aquilae
o* Capricorn!
p Capricorni..
Means
Its estimated uncertainty
0'20
... + 2%88
19 20
r of mean c
+ 56-76
arrection
0-037
±0-010
Probable erro
Adopted daily change — O40
Comparisons of Madras Chronometer used for Signalling.
Transit
Clock.
Sidereal
Correction.
Chronometer
Dent 1668.
Mean Time
Correction.
Transit
Clock.
Sidereal
Correction.
Chronometer
Dent 1668.
Mean Time
Correction.
1871, July 24.
1871, July 26.
h. in. s. s. h. m. s. s.
h. m. s. s. ht m. s. s.
17 45 2
+ 58-42
9 38 16
-2-20
17 46 1
+ 57-57
9 31 14
+ 5-97
20 24 2
+ 58-37
12 16 50
-2-30
19 46 6
+ 57-54
11 31 0
+ 5-27
1871, July 25.
1871, July 28.
17 55 28
+ 57-96
9 44 40
+ 1-72
18 12 37
+ 56-78
9 49 45
-H 14-01
20 25 3
+ 57-92
12 13 50
+ 2-17
20 54 0
+ 56-73
12 30 41
-f 14-52
16 TELEGEAPHIO LONGITUDE DETEEMINATIONS IN INDIA.
Madras and Singapore Time Corrections, 1871, July 24.
At 9 h. 38 TO. by Mr. Pogson's Chronometer Dent 1668, it was 2*20 seconds fast of Madras Mean Time,
with an adopted daily rate of 0*91 second gaining.
At ISA. 52*5 TO. by Prof. Oudeman's. Chronometer Schmidt 325, it was 2m. 20*57 s. fast of Singapore
Mean Time, with an adopted daily rate of 2*07 seconds losing.
Hence at 11 h. 13m. by Chronometer Dent 1668, the relative correction was 2 TO. 18*40 s. and its
change— 0*00207 second per minute.
Telegra^ hie Signals from Madras to Singapore.
Madras
Signals.
Singapore
Eecords.
Difference
Sing. — Mad.
Relative
Correction.
Singapore
East.
Residual
Errors.
h. m. . s.
h. m. s.
h. m. $.
m. s.
h. TO. s.
*
s.
10 45 0
12 21 42*50
I 36 42*50
2 18*46
1 34 24*04
+ 0-01
45 15
21 57*35
36 42*35
2 18*46
34 23*89
-0*14
45 30
22 12*50
36 42*50
2 18*46
34 24*04
+ 0*01
45 45
22 27*50
36 42*50
2 18*46
34 24*04
+ 0*01
46 0
22 42*45
36 42*45
2 18*46
34 23*99
- 0*04
46 15
22 57*50
36 42*50
2 18*46
34 24*04
+ 0*01
46 30
23 12*40
36 42*40
2 18*45
34 23*95
-0*08
46 45
23 27*45
36 42*45
2 18*45
34 24*00
-0*03
47 0
23 42*50
36 42*50
2 18*45
34 24*05
+ 0*02
47 15
23 57*50
36 42*50
2 18*45
34 24*05
+ 0*02
47 30
24 12*45
36 42*45
2 18*45
34 24*00
-0*03
57 30
34, 12*50
36 42*50
2 18*43
34 24*07
4-0*04
57 45
34 27*45
36 42*45
2 18*43
34 24*02
-0*01
53 0
34 42*50
36 42*50
2 18*43
34 24*07
+ 0*04
58 15
34- 57*50
36 42*50
2 18*43
34 24*07
+ 0*04
58 45
35 27*50
36 42*50
2 18*43
34 24*07
+ 0*04
59 0
35 42*50
36 42*50
2 18*43
34 24*07
+ 0*04
59 15
35 57*50
36 42*50
2 18*43
34 24*07
+ 0*04
59 30
36 12*40
36 42*40
2 18*43
34 23*97
-0*06
59 45
36 27*50
36 42*50
2 18*43
•
34 24*07
+ 0*04
11 0 0
12 36 42*50
1 36 42*50
2 18*43
34 24*07
+ 0*04
11 . 52 12*86
12 28 55*33
1 36 42*47
• 2 18*44
1 34 24*03
0*038
TELEGRAPHIC SIGNALS.
Telegraphic Signals from Singapore to Madras, 1871, July 24.
17
Madras
Eecorda.
Singapore
Signals.
Difference.
Sing. — Mad.,
Relative
Correction.
Singapore
East.
Residual
Errors.
h. in. s.
h. m. s.
h. in. s.
m. s.
h. m. s.
s.
10 50 34-0
12 27 15-50
1 36 41-50
2 18-45
1 34 23-05
+ 0-16
50 49-0
27 30-35
36 41-35
2 18-45
34 22-90
+ 0-01
51 4'4
27 45-60
36 41-20
2 18-45
34 22-75
-0-14
51 33-9
28 15-05
36 41-15
2 18-44
34 22-71
-0-18
51 48'5
28 30-10
36 41-60
2 18-44
34 23-16
+ 0-27
52 4-0
28 45-25
36 41-25
2 18-44
34 22-81
-0-08
52 19-0
29 0-30
36 41-30
2 18-44
34 22-86
-0-03
52 34-0
29 15-40
36 41-40
2 18-44
34 22-96
+ 0-07
52 48-6
29 30-00
36 41-40
2 18-44
34 22-96
+ 0-07
53 4-0
29 45-30
36 41-30
2 18-44
34 22-86
-0-03
53 19-0
30 0-25
36 41-25
2 18-44
34 22-81
-o-os
11 1 34-0
38 14-95
36 40-95
2 18-42
34 22-53
-0-36
1 48-9
38 30-20
36 41-30
2 18-42
34 22-88
-o-oi
2 4-0
38 45-25
36 41-25
2 18-42
34 22-83
-0-06
2 18-8
39 0-40
36 41-60
2 18-42
34 23-18
+ 0-29
2 33-6
39 15-00
36 41-40
2 18-42
34 22-98
+ 0-09
2 48-5
39 29-95
36 41-45
2 18-42
34 23-03
+ 0-14
3 4-0
39 45-50
36 41-50
2 18-42
34 23-08
+ 0-19
3 19-0
40 0-30
36 41-30
2 18-42
34 22-88
-o-oi
3 33-8
40 15-05
36 41-25
2 18-42
34 22-83
-0-06
3 49-0
40 30-25
36 41-25
2 18-42
34 22-83
-0-06
4 4-0
40 45-25
36 41-25
2 18-42
34 22-83
-0-06
11 4 19-0
12 41 0-25
1 36 41-25
2 18-42
1 34 22-83
-0-06
10 57 42-39
12 34 23-71
1 36 41-32
2 18-43
1 34 22-89
0-109
18
TELEGRAPHIC LONGITUDE DETERMINATIONS IN INDIA.
Madras and Singapore Time Corrections, 1871, July 25.
At 9/i. 45m. by Mr. Pogson's Chronometer Deut 1668, it was 1'72 seconds slow of Madras Mean Time, with
an adopted daily rate of 4 34 seconds losing.
At I7h. 30m. by Prof. Oudeman's Sidereal Chronometer Hohwn 394, it was 24'56 seconds slow of Singa-
pore Sidereal Time, with an adopted daily rate of 2'33 seconds losing.
Hence at Wh. 45m. by Chronometer Dent 1668, the relative correction was 8h. llm. 31'20s. and its
change -}- 0-16567 second per minute.
Telegraphic Signals from Madras to Singapore, 1871 , July 25.
Madra.s
Signals.
Singapore
Records.
Difference.
Sing. — Mad.
Relative
Correction.
Singapore
East.
Rosidual
Errors.
h. m. s.
h. m. s.
h. m. s.
h. m. s.
h. m. s.
*
s.
10 35 15
20 21 8-50
9 45 53-50
8 11 29-58
I 34 23-92
- 0-11
35 30
21 23-65
45 53-65
11 29-63
34 24-02
- o-oi
35 45
21 38-80
45 53-80
11 29-67
34 24-13
+ 0-10
36 0
21 53-80
45 53-80
11 29-71
34 24-09
+ 0-06
36 15
22 ' 8-80
45 53-80
11 29-75
34 24-05
+ 0-02
36 30
22 23-90
45 53-90
11 29-79
34 24-11
+ 0-08
36 45
22 39-00
45 54-00
11 29-83
34 24-17
+ 0-14
37 0
22 54-00
45 54-00
11 29-87
34 24-13
+ 0-10
37 15
23 9-00
45 54-00
11 29-91
34 24-09
+ 0-06
37 30
23 24-00
45 54-00
11 29-96
34 24-04
+ 0-01
37 45
23 39-00
45 54-00
11 30-00
34 24-00
- 0-03
38 0
23 54-00
45 54-00
11 30-04
34 23-96
- 0-07
49 15
35 ll'OO
45 56-00
11 31-90
34 24-10
+ 0-07
49 30
' 35 26-00
45 56-00
11 31-94
34 24-06
+ 0-03
49 45
35 41-00
45 56-00
11 31-99
34 24-01
- 0-02
50 0
35 56-05
45 56-05
11 32-03
34 24-02
- o-oi
50 15
36 11-10
45 56-10
11 32-07
34 24-03
o-oo
50 30
36 26-10
45 56-10
11 32-11
34 23-99
- 0-04
50 45
36 41-05
45 56-05
11 32-15
34 23-90
- 0-13
51 0
36 56-10
45 56-10
11 32-19
34 23-91
-0-12
51 15
37 11-15
45 56-15
11 32-23
34 23-92
- 0-11
51 30
37 26-25
45 56-25
11 32-27
34 23-98
- 0-05
51 45
37 41-25
45 56-25
11 32-32
34 23-93
- o-io
10 52 0
20 37 56-45
9 45 56-45
8 11 32-36
1 34 24-09
+ 0-06
10 43 37-50
20 29 32-50
9 45 55-00
8 11 30-97
1 34 ' 24-03
0-064
TELEGRAPHIC SIGNALS.
Telegraphic Signals from Singapore to Madras, 1871, July 25,
19
Madras
Records .
Singapore
Signals.
Difference.
Sing.— Mad.
Relative
Correction.
Singapore
East.
Residual
Errors.
h. rn. s.
h. in. s.
h. m. s.
h. TO. s.
h. m. s.
s.
10 44 21-0
20 30 15
9 45 54-0
8 11 31-09
1 34 22-91
+ 0-04
44 36-0
30 30
45 54-0
11 31-13
34 22-87
o-oo
44 50-9
30 45
45 54-1
11 31-17
34 22-93
+ 0-06
45 6-0
31 0
45 54-0
11 31-22
34 22-78
- 0-09
45 20-9
31 15
45 54-1
11 31-26
34 22-84
-0-03
45 36-0
31 30
45 54-0
11 31-30
34 22-70
-0-17
45 50-8
31 45
45 54-2
11 31-34
34 22-86
-o-oi
46 5-9
32 0
45 54-1
11 31-38
34 22-72
-0-15
46 20-5
32 15
45 54-5
11 31-42
34 23-08
+ 0-21
46 35-5
32 30
45 54-5
11 31-46
34 23-04
+ 0-17
46 50-6
32 45
45 54-4
11 31-50
34 22-90
+ 0-03
47 5-5
33 0
45 54-5
11 31-54
34 22-96
+ 0-09
53 34-5
39 30
45 55'5
11 32-62
34 22-88
+ 0-01
53 49-4
39 45
45 55'6
11 32-66
34 22-94
+ 0-07
54 4-5
40 0
45 55-5
11 32-70
34 22-80
-0-07
54 19-5
40 15
45 55-5
11 32-74
34 22-76
-0-11
54 34-5
40 30
45 55-5
11 32-78
34 22-72
- 0-15
54 49-5
40 45
45 55-5
11 32-83
34 22-67
- 0-20
55 4-4
41 0
45 55-6
11 32-87
34 22-73
-0-14
55 19-2
41 15
45 55-8
11 32-91
34 22-89
-f 0-02
55 34-1
41 30
45 55-9
11 32-95
34 22-95
+ 0-08
55 49-0
41 45
45 56-0
11 32-99
34 23-01
+ 0-14
56 4-0
42 0
45 56-0
11 33-03
34 22-97
+ 0-10 .
10 56 19'0
20 42 15
9 45 56-0
8 11 33-07
1 34 22-93
+ 0-06
10 50 20-05
20 36 15-00
9 45 54-95
8 11 32-08
1 34 22-87
0-092
20 TELEGRAPHIC LONGITUDE DETERMINATIONS IN INDIA.
Madras and Singapore Time Corrections, 1871, July 26.
At 9h. 31m. by Mr. Pogson's Chronometer Dent 1668, it was 5'97 seconds slow of Madras Mean Time, with
an adopted daily rate of 8 42 seconds gaining.
At 18?i. Om. by Prof. Oudeman's Chronometer Hohwn 394, it was 27'04 seconds slow of Singapore Sidereal
Time, with an adopted daily rate of 2'28 seconds losing.
Hence at lOh. 25m. by Chronometer Dent 1668, the relative correction was 87i. 15m. 25'83s. and its
change -j- 0*15685 second per minute.
Telegraphic Signals from Madras to Singapore, 1871, July 26.
Madras
Singapore
Difference.
Relative
Singapore
Residual
Signals.
Records.
Sing. — Mad.
Correction.
East.
Errors.
h. m. s.
h. TO. s.
h. TO. s.
h. TO. s.
h. TO. s.
s.
10 16 30
20 6 18-55
9 49 48-55
3 15 24-49
1 34 24-06
o-oo
16 45
6 33-60
49 48-60
15 24-53
34 24-07
+ 0-01
17 0
6 48-60
49 48-60
15 24-57
34 24-03
- 0-03
17 15
7 3-70
49 48-70
15 2461
34 24-09
4-0-03
17 30
7 18-65
49 48-65
15 24-65
34 24-00
-0-06
17 45
7 33-75
49 48-75
15 24-69
34 24-06
o-oo
18 0
7 48-65
49 48-65
15 24-73
34 23-92
- 0-14
18 15
8 3-75
49 48-75
15 24-77
34 23-98
- 0-08
18 30
8 18-80
49 48-80
15 24-81
34 23-99
-0-07
18 45
8 33-95
49 48-95
15 2485
34 24-10
4-0-04
19 0
8 49-00
49 49-00
15 24-89
34 24-11
4-0-05
31 15
21 6-00
49 51-00
15 26-81
34 24-19
4-0-13
31 30
21 21-00
49 51-00
15 26-85
34 24-15
4-0-09
31 45
21 36-00
49 51-00
15 26-89
34 24-11
4-0-05
32 0
21 51-05
49 51-05
15 2693
34 24-12
4-0-06
32 15
22 6-15
49 51-15
15 26-97
34 24-18
4-0-12
32 30
22 21-05
49 51-05
15 27-01
34 24-04
- 0-02
32 45
22 36-05
49 51-05
15 27-05
34 24-00
- 0-06
33 0
22 51-15
49 51-15
15 27-08
34 24-07
4-0-01
33 15
23 6-10
49 51-10
15 27-12
34 23-98
- 0-08
33 30
23 21-25
49 51-25
15 27-16
34 24-09
4-0-03
33 45
23 36-20
49 51-20
15 27-20
34 24-00
- 0-06
10 34 0
20 23 51-20
9 49 51-20
8 15 27-24
1 34 23-96
- o-io
10 25 30-65
20 15 20-62
9 49 49-97
8 15 25-91
1 34 24-06
0-057
TELEGRAPHIC SIGNALS-
•
Telegraphic Signals from Singapore to Madras, 1871, July 26.
21
Madras
Records.
Singapore
Signals.
Difference.
Sing. — Mad.
Relative
Correction.
Singapore
East.
Residnal
Errora.
h. in. s.
h. m. s.
h. m. s.
h. m. s.
h. m. s.
5.
10 20 42-1
20 10 30
9 49 47'9
8 15 25-16
1 34 22-74
-0-24
20 56-9
10 45
49 48-1
15 25-19
34 22-91
-0-07
21 12-0
21 26-8
11 0
11 15
49 48-0
49 48-2
15 25-23
15 25-27
34 22-77
34 22-93
-0-21
- 0-05
21 41-9
11 30
49 48-1
15 25-31
34 22-79
-0-19
21 56-6
11 45
49 48-4
15 25-35
34 23-05
+ 0-07
22 11-5
12 0
49 48-5
15 25-39
34 23-11
+ 0-13
22 26-5
12 15
49 48-5
15 25-43
34 23-07
+ 0-09
22 41-6
12 30
49 48-4
15 25-47
34 22-93
-0-05
22 56-5
12 45
49 48-5
15 25-81
34 22-99
+ o-oi
23 11-5
13 0
49 48-5
15 25-55
34 22-95
- 0-03
23 26-5
13 15
49 48-5
15 25-59
34 22-91
-0-07
35 24-5
25 15
49 50-5
15 27-46
34 23-04
+ 0-06
35 39-5
25 30
49 50-5
15 27-50
34 23-00
+ 0-02
35 54-5
25 45
49 50-5
15 27-54
34 22-96
- 0-02
36 9'5
26 0
49 50-5
15 27-58
34 22-92
-0-06
36 24-4
26 15
49 50-6
15 27-62
34 22-98
o-oo
36 39-4
26 30
49 50-6
15 27-66
34 22-94
-0-04
36 54-3
26 45
49 50-7
15 27-70
34 23-00
+ 0-02
37 9-2
27 0
49 50-8
15 27-74
34 23-06
+ 0-08
37 24-0
27 15
49 51-0
15 27-78
34 23-22
+ 0-24
37 39-1
27 30
49 50-9
15 27-81
34 23-09
+ 0-11
37 54-0
27 45
49 51-0
15 27-85
34 23-15
+ 0-17
10 38 9-1
20 28 0
9 49 50-9
8 15 27-89
1 34 23-01
+ 0-03
10 29 25-50
20 19 15-00
9 49 49-50
8 15 26-52
1 34 22-98
0-086
22 TELEGRAPHIC LONGITUDE DETERMINATIONS IN INDIA.
Madras and Singapore Time Corrections, 1871, July 28.
At 9/i. 50m. by Mr. Pogson's Chronometer Dent 1668, it was 14 01 seconds slow of Madras Mean
Time, with an adopted daily rate of 4'56 seconds losing.
At 22h. 40m. by Professor Oudeman's Chronometer Hohwn 394, it was 32"40 seconds slow of Singapore
Sidereal Time, with an adopted daily rate of 2'88 seconds losing.
Hence at Wh. 33m,. by Chronometer Dent 1668, the relative correction was 8h. 23m. 23'88s. and its
change + 0 16545 seconds per minute. .
Telegraphic Signals from Madras to Singapore, 1871, July 28.
Madras
Signals.
Singapore
Records.
Difference.
Sing. — Mad.
Relative
Correction.
Singapore
East.
Residual
Errors.
*
h. TO. s.
h. m. s.
h. m. s.
h. m. s.
h. m. s.
s.
10 30 15
20 28 2-85
9 57 47-85
8 23 23-43
1 34 24-42
+ 0-05
30 30
28 17-95
57 47-95
23 23-47
34 24-48
+ 0-11
30 45
28 32-95
57 47-95
23 23-51
34 24-44
4-0-07
31 0
28 47-90
57 47-90
23 23-55
34 24-35
- 0-02
31 15
29 3-00
57 48-00
23 23-59
34 24-41
+ 0-04
31 30
29 18-00
57 48-00
23 23-63
34 24-37
o-oo
31 45
29 33-00
57 48-00
23 23-67
34 24-33
-0-04
32 0
29 48-05
57 48-05
23 23-71
34 24-34
- 0-03
32 15
30 3-10
57 48-10
23 23-76
34 24-34
-0-03
32 30
30 18-10
57 48-10
23 23-80
34 24-30
-0-07
32 45
30 33-05
57 48-05
23 23-84
34 24-21
-0-16
33 0
30 48-25
57 48-25
23 23-88
34 24-37
o-oo
39 15
37 4-50
57 49-50
23 24-91
34 24-59
+ 0-22
39 30
37 19-35
57 49-35
23 24-96
34 24-39
4-0-02
39 45
37 34-35
57 49-35
23 25-00
34 24-35
-0-02
40 0
37 49-40
57 49-40
23 25-01
34 24-36
- o-oi
40 15
38 4-50
57 49-50
23 25-08
34 24-42
4-0-05
40 30
38 19-50
57 49-50
23 25-12
34 24-38
+ 0-01
40 45
38 34-50
57 49-50
23 25-16
34 24-34
- 0-03
41 0
38 49-55
57 49-55
23 25-20
34 24-35
-0-02
41 15
39 4-55
57 49-55
23 25-25
34 24-30
- 0-07
10 41 30
20 39 19-60
9 57 49-60
8 23 25-29
1 34 24-31
-0-06
10 35 36-14
20 33 24-82
9 57 48-68
8 23 24-31
1 34 24-37
0-051
TELEGRAPHIC SIGNALS.
Telegraphic Signals from Singapore to Madras, 1871, July 28.
23
Madras
Singapore
Difference.
Relative
Singapore
Residual
Records.
Signals.
Sing. — Mad.
Correction.
Bast.
Errors.
h. iu. s.
h. m. s.
h. m. s.
h. m. s.
h. TO. s.
s.
10 34 12-6
20 32 0
9 57 47'4
8 23 24-08
1 34 23-32
+ 0-03
34 27-5
32 15
57 47-5
23 24-12
34 23-38
+ 0-09
34 42-4
32 30
57 47-6
23 24-16
34' 23-44
+ 0-15
34 57'5
32 45
57 47-5
• 23 24-20
34 23-30
+ 0-01
35 12-5
33 0
57 47-5
23 24-24
34 23-26
-0-03
35 27-5
33 15
. 57 47-5
23 24-29
34 23-21
-0-08
35 42-4
33 30
57 47-6
23 24-33
34 23-27
-0-02
35 57-5
33 45
57 47-5
23 24-37
34 23-13
- 0-16
36 12-3
34 0
57 477
23 24-41
34 23-29
o-oo
36 27-4
34 15
57 47-6
23 24-45
34 23-15
- 0-14
36 42-1
34 30
57 47-9
23 24-49
34 23-41
+ 0-12
36 57-0
34 45
57 48-0
23 24-53
34 23-47
+ 0-18
• 43 11-2
41 0
57 48-8
23 25-57
34 23-23
- 0-06
43 26-0
41 15
57 49-0
23 25-61
34 23-39
+ 0-10
43 41-0
41 30
57 49-o'
23 25-65
34 23-35
+ 0-06
43 56-0
41 45
57 49-0
23 25-69
33 23-31
+ 0-02
44 11-0
42 0
57 49-0
23 25-73
34 23-27
- 0-02
44 26-0
42 15
57 49-0
23 25-77
34 23-23
-0-06
44 40-9
42 30
57 49-1
23 25-81
34 23-29
o-oo
44 55-9
42 45
57 49-1
23 25-85
34 23-25
-0-04
45 10-8
43 0
57 49-2
23 25-89
34 23-31
+ 0-02
45 26-0
43 15
57 4*9-0
23 25-94
34 23-06
- 0-23 .
45 40-8
43 30
57 49-2
23 25-98
34 23-22
- 0-07
10 45 55-6
20 43 45
9 57 49-4
8 23 26-02
1 34 23-38
-fO-09
10 40 4-16
20 37 52-50
9 57 48-34
8 23 25-05
1 34 23-29
0-074
24
TELEGEAPHIC LONGITUDE DETERMINATIONS IN INDIA.
Summary of Telegraphic Results.
1871.
Number of Signals.
Singapore
East.
Probable
Errors.
Compound
Retardation.
h. m. s.
s.
s.
July 24 ...
» » •••
By 21 from Madras
By 23 from Singapore
1 34 24-03
1 34 22-88
±'0-007
± 0-019
0-575
„ 25...
» » •••
By 24 from Madras
By 24 from Singapore
1 34 24-03
1 34 22-87
± 0-011
± 0-016
0-580
„. 26 ...
» » •••
By 23 from Madras
By 24 from Singapore
1 34 24-06
1 34 22-98
± o-oio
± 0-015
0-540
„ 28...
By 22 from Madras
1 34 24-37
± 0-009
0-540
>» » • ••
By 24 from Singapore
1 34 23-29
± 0-013
*
Final Results.
h. m. s.
Madras Observatory East of Greenwich 5 20 59 "40
Singapore East of Madras .' 1 34 23'56
Singapore East of Greenwich 6 55 22*96
Probable Error of Signals and Madras Transits ± Of014
Compound Retardation (Current and Instruments). 0'549
AVANASHI. 25
AVANASHI.
A Government expedition being sanctioned for the observations of
the Total Eclipse of the Sun which swept across Southern India on 1871,
December 12th, the Railway Station nearest to the central line of totality
naturally suggested itself as most convenient for the transport of a staff of
observers, instruments, tents and all camp requisites, and with the kind
permission of Mr. R. B. Elwin, Agent and Manager of the Madras Railway
Company, the grounds of the Avanashi Station, in Coimbatore District,
were selected for the purpose. Mr. G. K. Winter, the Company's Te-
legraph Engineer, who so ably assisted me upon a similar occasion at Masu-
lipatam, in August, 1868, having again undertaken the polarisation obser-
vations of the Solar Corona, I was further favored with the use of the
line to make a telegraphic longitude comparison with the Madras Observa-
tory.
The point of reference at Avanashi was a small brick column, north-
east of the Railway Station, built to hold the portable transit instrument
brought from Madras. The transit instrument itself , an old one by Dollond,
repaired but not improved, was very unsatisfactory in its level adjustment.
Only four clock stars were observed either at Madras or at Avanashi on
the night of the longitude operations, but the relative personal .equations of
the operators being known considerably within the limits of fluctuation to
which such individual peculiarities or habits are liable, the longitude of
Avanashi is probably more definitely settled than that of any other place in
the determination of which I have participated.
My chief native assistant, the late C. E/agoonatha Gharry, having only
just returned to Madras, the signals were exchanged between him, at the
Royaporam terminus of the line, about five miles from the Observatory,
and myself at Avanashi. The noisy interruption of a train, arriving just as
the records were commenced, led me to ask for more signals from Madras,
but, as shown by the residual errors, really without cause. At each stati'on
a mean time chronometer was compared with the sidereal clock or chrono-
meter by which the transits were observed, and was then carefully carried
to the telegraph office as on previous occasions.
26 TELEGRAPHIC LONGITUDE DETERMINATIONS IN .INDIA.
Local Sidereal Time Determinations, 1870, December 14.
MADRAS.
AVANASH1.
• Name of
Star.
Transit
Clock.
Sidereal
Correction.
Residual
Errors.
Name of
Star.
Chronometer
Hatton and
Harris.
Sidereal
Correction.
Residual
Errors.
6 Ceti .
h. m.
1 18
1 48
3 16
3 40
s.
— 23-35
— 23-54
— 23-46
— 23-50
s.
+ 0-06
— 0-11
+ 0-03
+ 0-01
61 Tauri
Aldebaran...
8 Orionis
e Orionis
h. m.
4 16
4 29
5 26
5 30
s.
- 12-24
— 11-52
„ 1 1 -OO
s.
ft. OK
)8 Arietis
+ 0-37
— 0-11
+ 0-07
Alcyone
— 11-80
2 30
— 23'46
0-053
Means .
4 55
— 11'88
*
0-225
Probable Err<
Adopted daily
)r of Mean (
chancre
Correction +0-026
Probable En-
Adopted dail;
or of mean co
T chansre
rrfiptifvn -- --v *t~ fl'1 10
— 1-00
-i- n-;u
Comparisons of Chronometers used for Signalling.
Transit
Clock.
Sidereal
Correction-
Chronometer
Arnold and
Dent 1337.
Mean Time
Correction.
Chronometer
Hatton and
Harris.
Sidereal
Correction.
Chronometer
Dent. 1668.
Mean Time
Correction.
h. m. s.
169
4 3 49
1870, De<
s.
-23-40
-23-53
member 14.
li. m. s.
7 34 30
10 31 40
s.
+ T97
+ 2-73
h. m. s.
2 45 35
8 1 44
1870, Dec*
s.
*- 12-25
1870, Dec
-11-84
xnber 13.
h. m. s.
9 28 40
3mber 14.
14 40 1
m. $.
- 10 53-20
- 10 52-60
TIME CORRECTIONS AND TELEGRAPHIC SIGNALS. 27
Madras and Avanashi Time Corrections, 1871, December 14.
At 16 h. 32 TO. by C. Eagoonatha Chary's Chronometer, Arnold and Dent 1337, it was 2'73 seconds slow of
Madras Mean Time, with an adopted daily rate of 6'16 seconds losing.
At 14 h. 40 ra. by Mr. Pogson's Chronometer, Dent 1668, it was 10 m. 52'60 s. fast of Avanashi Mean
Time, with an adopted daily rate of 0*49 second losing.
Hence at 9 h. 15 m. by Arnold and Dent 1337, the relative correction was 10 m. 55'11 s. and its change
+ 0*00394 second per minute.
Telegraphic Signals from Madras to Avanashi, 1871, December 14.
Madras
Signals.
Avanashi
Records.
Difference.
Mad. — Avan.
Relative
Correction.
Avanashi
West.
Residual
Errors.
h. m. s.
h, m. s.
8.
m. s.
m. s.
s.
8 51 15
8 50 31*0
44-0
10 55-02
11 39-02
o-oo
51 30
50 46-0
44-0
10 55-02
11 39-02
o-oo
51 45
51 1-2
438
10 55-02
11 38-82
-0-20
52 0
51 16-0
44-0
10 55-02
11 39-02
o-oo
52 15
51 31-1
43-9
10 55-02
11 38-92
-o-io
62 30
61 46-0
44-0
10 55-02
11 39-02
o-oo
52 45
62 1-0
44-0
10 55-02
11 39-02
o-oo
53 0
52 16*2
43-8
10 55-02
11 38-82
- O'2'O
53 15
52 31-0
44-0
10 55-02
11 39-02
o-oo
63 30
52 46-0
44-0
10 55-03
11 39-03
+ 0-01
53 45
53 1-0
44-0
10 55-03
11 39-03
+ 0-01
54 0
53 16-2
43-8
10 55-03
11 38-83
-0-19
54 15
53 31*0
44-0
10 55-03
11 39-03
H-o-oi
54 30
53 46-1
43-9
10 55-03
11 38-93
-0-09
55 0
54 16-0
44-0
10 55-03
11 39-03
+ 0-01
55 15
54 31-0
44-0
10 55-03
11 39-03
+ 0-01
55 45
55 1-0
44-0
10 55-03
11 39-03
+ 0-01
66 0
55 16-0
440
10 55-04
11 39-04
+ 0-02
66 15
55 31-0
44-0
10 5504
11 39-04
+ 0-02
66 30
55 46-0
44-0
10 55-04
11 39-04
+ 0-02
66 45
66 I'O
44-0
10 55-04
11 39-04
+ 0-02
57 0
56 16-0
44-0
10 5504
11 39-04
+ 0-02
67 15
66 31-0
44-0
10 55-04
11 39-04
-f-0-02
68 30
57 46-0
44-0
10 55-04
11 39-04
+ 0-02
8 58 45
8 58 1-0
44-0
10 55-05
11 39-05
+ 0-03
28 TELEGRAPHIC LONGITUDE DETERMINATIONS IN INDIA.
Telegraphic Signals from Madras to Avanashi, 1871, December, 14.
Madras
Avanashi
Difference.
Relative
Avanashi
Residual
Signals.
Records.
Mad. — Avan.
Correction.
East.
Errors.
h. m. s.
h. m. s.
s.
m. s.
TO. S.
s.
8 59 0
8 58 16-0
44-0
10 55-05
11 39-05
+ 0-03
59 15
58 31-0
44-0
10 5505
11 39-05
+ 0-03
59 30
58 46-0
44-0
10 55-05
11 39-05
+ 0-03
59 45
59 1-0
44-0
10 55-05
11 39-05
+ 0-03
900
59 16-1
43-9
10 55-05
11 38-95
+ 0-07
0 15
59 30-9
44-1
10 55-05
11 39-15
+ 0-13
0 30
59 46-0
44-0
10 55-05
11 39-C5
+ 0-03
0 45
9 0 1-0
44-0
10 55-05
11 39-05
+ 0-03
1 0
0 16-0
44-0
10 55-05
11 39-05
+ 0-03
1 15
0 31-2
43-8
10 55-06
11 38-86
- 0-16
1 30
0 46-0
44-0
10 55-06
11 39-06
+ 0-04,
1 45
i ro
44-0
10 55-06
11 39-06
+ 0-04
2 0
1 16-0
44-0
10 55-06
11 39-06
+ 0-04
2 15
1 31-0
44-0
10 5506
11 39-06
+ 0-04
2 30
1 46-0
44-0
10 55-06
11 39-06
+ 0-04
2 45
2 1-0
44-0
10 55-06
11 39-06
+ 0-04
3 0
2 16'0
44-0
10 55-06
11 39-06
-I-0-04
3 15
2 31-0
44-0
10 55-06
11 39-06
+ 0-04
3 30
2 46-0
44-0
10 55-06
11 39-06
+ 0-04
3 45
3 1-1
43-9
10 55-07
11 38-97
-0-05
20 15
19 31-2
43-8
10 55-13
11 38-93
- 0-09
20 30
19 46-1
43-9
10 55-13
11 39-03
+ 0-01
20 45
20 1-0
44-0
10 55-13
11 39-13
+ 0-11
21 0
20 16-2
43-8
10 55-13
11 38-93
- 0-09
21 15
20 31-2
43-8
10 55-13
11 38-93
- 0-09
21 30
20 46-0
44-0
10 55-14
11 39-14
+ 0-12
21 45
21 1-3
43-7
10 55-14
11 38-84
-0-18
22 0
21 16-1
43-9
10 55-14
11 39-04
+ 0-02
22 15
21 31-3
43-7
10 55-14
11 38-84
-0-18
22 30
21 46-1
43-9
10 55-14
11 39-04
+ 0-02
22 45
22 1-0
44-0
10 55-14
11 39-14
+ 0-12
23 0
22 16-1
43-9
10 55-14
11 39-04
+ 0-02
23 15
22 31-1
43-9
10 55-14
11 39-04
+ 0-02
23 30
22 46-1
43-9
10 55-14
11 39-04
+ 0-02
9 23 45
9 23 1-0
44-0
10 55-14
11 39-14
+ 0-12
9 3 40-75
9 2 56-80
43-95
10 55-07
11 39-02
0-053
AVANASHI TELEGRAPHIC SIGNALS AND RESULTS.
Telegraphic Signals from Avanashi to Madras, 1871, December 14.
29
Madras
Eecords.
Avanashi
Signals.
Difference.
Mad. — A van.
Relative
Correction.
Avanashi
West.
Residual
Errors.
h. m. s.
h. m. s.
s.
m. s.
m. s.
s.
9 10 59-1
9 10 15
44-1
10 55-09
11 39-19
+ 0-10
11 14-0
10 30
44-0
10 55-10
11 39-10
+ 0-01
11 28-9
10 45
43-9
10 55-10
11 39-00
-0-09
11 43-9
11 0
43-9
10 55-10
11 39-00
-0-09
11 59-0
11 15
44-0
10 55-10
11 39-10
+ 0-01
12 14-0
11 30
44-0
10 55-10
11 39-10
+ 0-01
12 28-8
11 45
43-8
10 55-10
11 38-90
-0-19
12 43-8
12 0
43-8
10 55-10
11 38-90
- 0 19
12 58-9
12 15
43-9
10 55-10
11 39-00
-0-09
13 14-0
12 30
44-0
10. 55-10
11 39-10
+ 0-01
13 29-0
12 45
44-0
10 55-10
11 3910
+ 0-01
13 44-0
13 0
44-0
10 55-11
11 39-11
+ 0-02
13 59-1
13 15
44-1
10 55-11
11 39-21
+ 0-12
14 14-0
13 30
44-0
10 55-11
11 39-11
+ 0-02
14 29-0
13,45
44-0
10 55-11
11 39-11
+ 0-02
14 44-1
14 Q
44-1
10 55-11
11 39-21
+ 0-12
14 59-0
14 15
44-0
10 55-11
11 39-11
+ 0-02
15 14-0
14 30
44-0
10 55-11
11 39-11
+ 0-02
15 29-1
14 45
44-1
10 55-11
11 39-21
+ 0-12
9 15 44-0
9 15 0
44-0
10 55-11
11 39-11
+ 0-02
9 13 21-49
9 12 37-50
43-99
10 55-10
11 39-09
0-064
... 11 3
U \J64
9'09
T~ \j \j\j\j
± 0'012
Final Results.
•
h.
m.
S.
Madras Observatory East of Greenwich.
... 5
20
59-40
Avanashi Transit Pillar "West of Madras.
...
11
39-05
Avanashi Transit Pillar East of Greenwich.
... 5
9
20-35
Probable Error of Signals and Transits.
...
± 0-114
Retardation. (Current and Instruments.)
...
0-035
30 TELEGRAPHIC LONGITUDE DETERMINATIONS IN INDIA.
JAFFNA.
Longitude determinations of Jaffna and Colombo, in Ceylon, were
requested by Captain (now Lieut- Colonel) J. L. Tupman, R. M. A., in con-
nection with his observations of the total eclipse of the Sun, on 1871, Decem-
ber llth. The Madras Observatory expedition to Avanashi for the same
purpose prevented any exchanges of signals before the eclipse, but C. Ragoo-
nathachary, the first native assistant, having been sent back immedi-
ately after, to aid in the Avanashi longitude determination, and Captain
Tupman being desirous of leaving Jaffna as soon as possible, the first
exchange was carried out on December 15th, before my return to Madras.
The second, on December 16th was between Captain Tupman and myself.
On both these occasions the comparison and transport of a mean time
chronometer was for the first time dispensed with, thanks to the obliging
arrangements of P. V. Luke, Esq., the Officer in charge at the Madras
Government Telegraph Office, who made temporary connections with the
line from the Observatory used for firing the Fort Time Signal Gun ; thereby
enabling the signals to be given and recorded frqm the transit clock
direct, instead of as before, by the intervention of a chronometer.
The geographical point of reference at Jaffna was a stone pier, erected
on purpose near the centre of the open parade ground within the Fort.
The observations for local time were double altitudes of the Sun, taken by
Captain Tupman, with an excellent three vernier reflecting circle by Messrs.
Troughton and Simms, and a mercurial artificial horizon. The time-piece
used was a very good marine chronometer, Muston, No. 610, beating half-
seconds and shewing a few minutes short of Greenwich mean time. The
probable errors of Captain Tupman' s time determinations could not well be
shewn, as the altitude observations were reduced in groups instead of singly ;
but from the quality of the instruments employed and the evident care and
skill of the observer, they must have been very small and would have made
but a trifling increase in the probable error of the final result.
It is to be regretted that Captain Tupman's detailed records did not
reach me until 1876, January 30th, and still more that a further and yet
longer interval elapsed before I could again give the subject due atten-
tion. The subsequently far better established longitude of the Madras Ob-
servatory and the final deduction of the personal equations of each of my
assistants enable me however, now to furnish final values, entitled to far
more reliance than earlier reductions would have yielded.
LOCAL TIME DETERMINATIONS.
Madras Sidereal Time Determinations.
31
Name of
Star.
Transit
Clock.
Sidereal
Correction.
Eesidual
Errors.
Name of
Star.
Transit
Clock.
Sidereal
Correction.
Eesidual
Errors.
1871, December 15.
1871, December 16.
h. m.
s.
s.
h. m.
s.
s,
t Piscium
23 34
- 24-37
- 0-02
i Piscium
23 34
- 25-30
- 0-04
8 Sculptoris...
23 43
- 24-33
+ 0-02
8 Sculptoris ..
23 43
- 25-33
- 0-07
<a Piscium. ...
23 53
- 24-34
+ 0-02
w Piscium ....
23 53
- 25-27
o-oo
a Andromeda?
7 Pegasi
12 Ceti...
0 2
0 7
0 24
0 38
1 48
- 24-40
- 24-36
- 24-40
- 24-37
- 24-49
- 0-04
+ 0-01
- 0-02
+ 0-02
- 0-06
aAndromedEe
•y Pegasi. .. .
0 2
0 7
0 24
0 38
3 52
- 25-40
- 25-27
• -25-36
- 25-28
- 25-42
-0-13
+ 0-01
-0-07
+ 0-01
o-oo
12 Ceti
)3 Ceti ....
# Ceti
j3 Arietis
71 Eridani....
Aldebaran... .
Kigel
4 29
5 9
- 24-51
-, 24-50
+ 0-03
+ 0-07
o Eridani
4 6
4 22
- 25-41
- 25-20
+ 0-02
+ 0-24
Means
1 11
- 24-41
0-031
• Mean. ..
1 16
- 25-32
0-059
Probable error of mear
Adopted daily change.
correction ± 0*010
— 0'96
Probable error of mean
Adopted daily change..
correction .'. ±0*020
_ Q-92
Jaffna Mean Time Determinations.
1871, December 13.
By five double altitudes of the Sun's upper limb,
followed by five more of the lower limb ; taken with
a reflecting circle by Troughton & Simms, in re-
versed positions of both circle and artificial horizon,
between 8 and 9 A.M. of December 14th, civil
reckoning ; — the Chronometer, Muston 610, was
5fe. 13m. 1214s. slow, when it shewed 157i. 24m. ;
corresponding to 207i. 38m. of Jaffna Mean Time,
on December 13th.
1871 December, 15, 16.
By ten double altitudes of the Sun's upper limb and
ten of the lower limb, taken with the same instru-
ments and precautions as before, between 8 and
9 A.M. of December 16th, civil reckoning, combined
with twenty more similar observations between 3
and 4 P.M., the Chronometer was 5h. 13m. 12'61s.
slow, when it shewed 18h. 54ra. ; corresponding to
Oh. 8m. of Jaffna Mean Time, on December 16th.
Its adopted daily rate was 0'22 second losing.
32 TELEGRAPHIC LONGITUDE DETERMINATIONS IN INDIA.
Madras and Jaffna Time Corrections, 187 1? December 15.
At lh. llm. by the Madras Transit Clock, it was 24'41 seconds fast of Sidereal Time, with an adopted
daily rate of 0'96 second gaining.
At Sh. 24m. by Captain Tupman's Chronometer, Muston 610, it was 5h. 13m. 12'47s. slow of Jaffna Mean
Time, with an adopted daily rate of 0'22 second losing.
Hence at 2h. 19m. by the Madras Transit Clock, the relative correction was lh. llm. T59s. and its
change — 0*16465 second per minute.
Telegraphic Signals from Madras to Jaffna, 1871, December 15.
Madras
Signals.
Jaffna
Records.
Difference.
Jaff. — Mad.
Relative
Correction.
Jaffna
West.
Residual
Errors.
h. m. s.
h. m. s.
h. m. . s.
h. m. s.
s.
s. *
2 11 15
3 21 20-20
1 10 5-20
I 11 2'87
57-67
+ 0-19
11 30
21 35-10
10 5-10
11 2-82
57-72
+ 0-24
11 45
21 50-20
10 5-20
11 2-78
57-58
+ 0-10
12 15
22 20-10
10 510
11 2-70
• 57-60
+ 0-12
12 30
22 35-05
10 5-05
11 2-66
57-61
+ 0-13
12 45
22 50-05
10 -5-05
11 2-62
57-57
+ 0-09
13 15
23 20-00
10 5-00
11 254
57-54
-f-0-06
13 30
23 34-95
10 4-95
11 2-50
57-55
+ 0-07
13 45
23 50-00
10 5-00
11 2-45
57-45
-0-03
14 15
24 19-90
10 4-90
11 2-37
57-47
-o-oi
. 14 30
24 34-90
10 4-90
11 2-33
57-43
-0-05
14 45
24 49-95
10 4-95
11 2-29
57-34
- 0'14
15 15
25 19-60
10 4-60
11 221
57-61
+ 0-13
15 30
25 34-55
10 4-55
11 2-17
57-62
+ 0-14
15 45
25 49-55
10 4-55
11 2-13
57-58
+ 0-10
16 15
26 19-50
10 4-50
11 2-04
57-54
+ 0-06
16 30
26 34-50
10 4-50
11 2-00
57-50
+ 0-02
16 45
26 49-45
10 4-45
11 1-96
57-51
+ 0-03
17 15
27 19-50
10 4-50
11 1-88
57-38
-o-io
17 30
27 34-50
10 4-50
11 1-84
57-34
-0-14
17 45
27 49-45
10 4-45
11 1-80
57-35
-0-13
18 15
28 19-20
10 4-20
11 1-71
57-51
+ 0-03
18 30
28 34-40
10 4-40
11 1-67
57-27
-0-21
18 45
28 49-20
10 4-20
11 1-63
57-43
-0-05
2 19 15
3 29 19-10
1 10 4-10
1 11 1-55
57-45
- 0-03
TELEGEAPHIC SIGNALS.
Telegraphic Signals from Madras to Jaffna, 1871, December 15.
33
Madras
Signals.
Jaffna
Records.
Difference.
Jaff.— Mad.
Relative
Correction.
Jaffna
West.
Residual
Errors.
k. in. s.
h. TO. s.
h. TO. s.
h. m. s.
s.
s.
2 19 30
3 29 34-05
1 10 4-05
1 11 1-51
57'46
- 0-02
19 45
29 49-05
10 4-05
11 1'47
57'42
-0-06
20 15
30 19-00
10 4-00
11 T38
57-38
- o-io
20 30
30 34-00
10 4'00
11 1-34
57-34
- 0-14
2 20 45
3 30 48-95
1 10 3-95
1 11 1-30
57-35
- 0-13
2 1C 0-00
3 26 4-60
1 10 4-60
1 11 2-08
57-48
0-95
Telegraphic Signals from Jaffna to Madras, 1871, December 15.
Madras
Records.
Jaffna
Signals.
Difference.
Jaff. — Mad.
Relative
Correction.
Jaffna
West.
Residual
Errors.
h. m. s.
•h. m. s.
"h. TO. s,
ft. TO. s.
s.
s.
2 25 57-3
26 12-1
3 36 0
36 15
1 10 2-7
10 2-9
1 11 0-44
11 0'40
57-74
57-50
+ 0-01
- 0-23
26 27-3
36 30
10 2-7
11 0-36
57-66
-0-07
26 42-2
36 45
10 2-8
11 0-32
57-52
- 0-21
27 12-3
37 15
10 27
11 0-24
57-54
-0-19
27 27-5
37 30
10 2'5
11 0-20
57-70
-0-03
27 42-6
28 12'7
28 277
37 45
38 15
38 30
10 2'4
10 2-3
10 2'3
11 0-16
11 0-08
11 0-03
57-76
57-78
57-73
+ 0-03
+ 0'05
o-oo
28 42-8
38 45
10 2'2
10 59-99
57-79
+ 0-06
29 13-0
39 15
10 2'0
10 59-91
5771
- 0-02
29 28'0
29 42-8
39 30
39 45
10 2-0
10 2-2
10 59-87
10 59-83
57-87
57-63
+ 0-14
- o-io
80 13-0
30 28-1
40 15
40 30
10 2'0
10 1-9
10 59-74
10 59-70
57-74
57-80
+ 0-01
+ 0-07
30 43-1
40 59-9
41 14-8
40 45
51 0
51 15
10 1'9
10 0-1
10 0'2
10 59-66
10 57-97
10 5793
57-76
57-87
57-73
+ 0-03
+ 0-14
o-oo
41 29-8
51 30
10 0-2
10 57-89
57-69
- 0-04
41 45-0
3 51 45
1 10 0-0
1 10 57-84
57-84
+ 0-11
34 TELEGRAPHIC LONGITUDE DETERMINATIONS IN INDIA.
Telegraphic Signals from Jaffna to Madras, 1871, December 15.
Madras
Records.
Jaffna
Signals.
Difference.
Jaff.— Mad.
Relative
Correction.
Jaffna
West.
Residual
Errors.
h. m. s.
h- m. s.
h. m. s.
7i. in. s.
s.
s.
2 42 15-0
3 52 15
1 10 O'O
1 10 57-76
57-76
+ 0-03
42 30'0
52 30
10 0-0
10 57-72
57-72
- o-oi
42 45-1
52 45
9 59'9
10 57-68
57-78
+ 0-05
43 15-2
53 15
9 59-8
10 57-60
57-80
+ 0-07
43 30-2
53 30
9 59-8
10 57-56
57-76
+ 0-03
43 45'3
53 45
9 597
10 57-52
57-82
+ 0-09
44 15-2
54 15
9 59-8
10 57-43
57-63
- o-io
44 30-3
54 30
9 59-7
10 57-39
57-69
- 0-04
44 45-2
54 45
9 59-8
10 57-35
57-55
- 0-18
45 15-3
55 15
9 59-7
10 57-27
57-57
- 0-16
45 30-3
55 30
9 59-7
10 57-23
57-53
- 0-20*
45 45-4
55 45
9 59-6
10 57-18
57-58
- 0-15
46 15'8
•56 15
9 59-2
10 57-10
57-90
+ 0-17
46 30-8
56 30
9 59-2
10 57-06
57-36
+ 0-13
46 45-9
56 45
9 59-1
10 57-02
57-92
+ 0-19
47 15-9
57 15
9 59-1
10 56-94
57-84
+ 0-11
47 31-0
57 30
9 59-0
10 56-90
57-90
+ 0-17
47 46-0
57 45
9 59-0
10 56-86
57-86
+ 0-13
48 31-0
58 30
9 59-0
10 56-73
57-73
o-oo
48 46-0
58 45
9 59-0
10 56-69
57-69
- 0-04
49 16-2
59 15
9 588
10 56-61
57-81
+ 0-08
49 31-2
59 30
9 58-8
10 56-57
57-77
+ 0-04
49 46-2
59 45
9 58-8
10 56-53
57-73
o-oo
50 16-3
4 0 15
9 58-7
10 56-44
57-74
+ 0-01
50 31-2
0 30
9 58-8
10 56-40
57-60
- 0-13
50 46-3
0 45
9 58-7
10 56-36
57-66
-0-07
2 51 1-3
410
1 9 58-7
1 10 56-32
57-62
-Oil
2 39 56-08
3 49 56-49
1 10 0-41
1 10 58-14
57-73
0-086
TIME COERECTIONS AND TELEGEAPHIO SIGNALS. 35
Madras and Jaffna Time Corrections, 1871, December 16.
At lh. IQin. by the Madras Transit Clock, it was 25'32 seconds fast of Sidereal Time, with an adopted daily
rate of 0"92 second gaining.
At 3h, 38m. by Captain Tnpman's Chronometer, Muston 610, it was 5h. 13m. 12"69s. slow of Jaffna Mean
Time, with an adopted daily rate of 0'22 second losing.
Hence at 2h. 19m. by the Madras Transit Clock, the relative correction was lh. 7»i. 4'56s. and ita
change — 0'16462 second per minute.
Telegraphic Signals from Madras to Jaffna, 1871, December 16.
Madras
Signals.
Jaffna
Records.
Difference.
Jaff.— Mad.
Relative
Correction.
Jaffna
West.
Residual
Errors .
h. m. s.
h. in. s.
h. m. s.
h. m. s.
8.
s.
2 15 15
3 21 23-2
1 6 8-2
1 7 5-18
56-98
-014
15 30
21 38-2
6 8-2
7 5-14
56-94
-0-18
15 45
21 53-0
6 8-0
7 5-10
57-10
- 0-02
16 15 •
22 23-2
6 8-2
7 5-01
56-81
-0-31
16 45
22 529
6 7-9
7 4-93
57-03
-009
17 15
23 22-7
6 7-7
7 4-85
57-15
+ 0-03
17 30
23 37-7
6 77
7 4-81
57-11
-o-oi
17 45
23 527
6 7-7
7 4-77
57-07
- 0-05
18 15
24 22-5
6 7-5
7 4-68
57-18
+ 0-16
18 30
24 37-5
6 7'5
7 4-64
57-14
-f-0-02
18 45
24 52-5
6 7'5
7 4-60
57-10
- 0-12
19 15
25 22-3
6 7-3
7 4-52
57-22
+ 0-10
19 30
25 37-3
6 7'3
7 4-48
57-18
+ 0-06
19 45
25 52-2
6 7-2
7 4-44
57-24
+ 0-12
20 15
26 22-2
6 7'2
7 4-35
57-15
+ 0-03
20 30
26 37-1
6 7-1
7 4-31
57-21
+ 0-19
20 45
26 52-1
6 7-1
7 4-27
57-17
+ 0-05
21 15
27 22-0
6 7-0
7 4-19
57-19
+ 0-07
21 30
27 37'0
6 7'0
7 4-15
57-15
+ 0-13
21 45
27 52-0
6 7'0
7 4-11
57-11
- 0-01
22 15
28 22-0
6 7-0
7 4-03
27-03
- 0-09
22 30
28 36-9
6 6-9
7 3-98
57-08
-0-04
22 45
28 51-8
6 6-8
7 3-94
57-14
H-0-02
23 15
29 21-7
6 67
7 3-86
57-16
+ 0-04
23 45
29 51-6
6 6-6
7 3-78
57-18
+ 0-06
24 15
30 21-5
6 6-5
7 3-70
57-20
+ 0-08
24 30
30 36-5
6 6-5
7 3-66
57-16
+ 0-04
2 24 45
3 30 51-5
1 6 6-5
1 7 3-61
57-11
-o-ii
36
TELEGRAPHIC LONGITUDE DETERMINATIONS IN INDIA.
Means of Signals from Madras to Jaffna, 1871, Dec. 16.
Madras
Signals.
Jaffna
Eecords.
Difference.
Jaff.— Mad.
Relative
Correction.
Jaffna
West.
Residual
Errors.
h. m. s.
h. m. s.
h. m. s.
h. m. s.
s.
s.
2 20 O'OO
3 26 7'28
1 6 7'28
1 7 4-40
5712
0-085
Telegraphic Signals from Jaffna to Madras, 1871, December 16.
Madras
Records.
Jaffna
Signals.
Difference.
Jaff.— Mad.
Relative
Correction.
Jaffna
West.
Residual
Errors.
h. m. s.
h. m. s.
h. m. s.
h. m. s.
s.
s.
2 27 9-1
3 33 15
1 6 5-9
I 7 3-23
57-33
-f-0'05
27 24-2
33 30
6 5-8
7 3-18
57-38
4- O'lO
27 39-1
33 45
6 5-9
7 3-14
57-24
— o-ot.
28 9-2
34 15
6 5-8
7 3-05
57-25
- 0-03
28 24:3
34 30
6 5-7
7 3-01
57-31
+ 0-03
38 39-2
34 45
6 5-8
7 2-97
57-17
- o-ti
29 9-4
35 15
6 5-6
7 2-89
57-29
+ 0-01
29 24-5
35 30
6 5-5
7 2-85
57-35
+ 0-07
29 39-5
35 45
6 5-5
7 2-81
57-31
+ 0-03
30 9-6
36 15
6 5-4
7 2-72
57-32
+ 0-04
30 24-5
36 30
6 5-5
7 2-68
57-18
- o-io
30 39-6
36 45
6 5-4
7 2-64
57-24
- 0-04
31 9-7
37 15
6 5-3
7 2-56
57-26
- 0-02
31 24-8
37 30
6 5-2
7 2-52
57-32
-t-0-04
31 40-0
37 45
6 5-0
7 2-48
57-48
+ 0-20
32 10-0
38 15
6 5-0
7 2-39
57-39
+ 0-11
32 25-0
38 30
6 5-0
7 2-35
5735
+ 0-07
32 40-0
38 45
6 5-0
7 2-31
57-31
+ 0-03
33 lO'l
39 15
6 4-9
7 2-23
57-33
+ 0-05
33 25-0
39 30
6 5-0
7 2-19
57-19
- 0-09
33 40-2
39 45
6 4-8
7 2-14
.57-34
+ 0-06
34 10-1
40 15
6 4-9
7 2-06
57-16
- 0-12
34 25-2
40 30
6 4-8
7 2-02
57-22
- 0-06
34 40-3
40 45
6 4-7
7 1-98
57-28
o-oo
35 10-4
41 15
6 4-6
7 1-90
57-30
-f 0-02
35 25-4
41 30
6 4-6
7 1-86
57-26
- 0-02
35 40-4
41 45
6 4-6
7 1-81
57-21
-0-07
36 10-6
42 15
6 4-4
7 1-73
57-33
-h 0-05-
36 25-5
42 30
6 4-5
7 1-69
57-19
- 0-09
2 36 40-5
3 42 45
1 6 4-5
1 7 1-65
57-15
-0-13!
TELEGRAPHIC SIGNALS AND EESULTS.
Means of Signals from Jaffna to Madras, 1871, December 16.
37
Madras
Records.
Jaffna
Signals.
Difference.
Jaff.— Mad.
Relative
Correction.
Jaffna
West.
Residual
Errors.
h. m. s,
h. m. s.
h. m. s.
h. m. s.
s.
s.
2 31 54-85
3 38 O'OO
1 6 5-15
1 7 2-43
57'28
0-063
Summary of Telegraphic Results.
1871.
Number of Signals.
Jaffna
West.
Probable
Errors.
Compound
Retardation.
s.
s.
s.
December 15
» )>
By 30 from Madras
By 47 from Jaffna
57-48
57-73
± 0-015
± 0-011
0-125
16
» >>
By 28 from Madras
By 30 from Jaffna
57-12
57-28
± 0-014
± o-oio
0-070
Final Results.
Madras Observatory East of Greenwich.
Jaffna Fort West of Madras
Jaffna Fort East of Greenwich. ...
Probable Error of Signals and Madras Transits..
Eetardation. (Current and Instruments.)
h.
5
m. s.
20 59-40
57-40
20 2-00
± 0-034
0-097
10
38
COLOMBO.
COLOMBO.
The longitude of Colombo, like that of Jaffna, was determined by desire
of Captain J. L. Tupman, R. M. A., in connection with the total eclipse of
the Sun on 1871, December llth, the arrangements being much the same
on both occasions. Signals were exchanged on three nights between
Madras and Colombo by Captain Tupman and myself and I believe with
results to our mutual satisfaction. The geographical point of reference
at Colombo was the Flagstaff, behind the Governor's Residence. At both
Jaffna and Colombo Captain Tupman expressed his great obligation for the
willing aid rendered him by G. Moberly, Esq., the Government Telegraph
official who had to assist him in all necessary electrical requirements, and
I have always had a similar acknowledgment to make from my own
experience in all cases in which the help of the Telegraph Department was
needed.
Local Sidereal and Mean Time Determinations.
MADRAS,
COLOMBO.
Star.
Transit
Clock.
Sidereal
Correction.
Kesidual
Errors.
Mean Time Chronometer, Muston 610.
67 Ceti
I* Ceti
1871, De
h. m.
2 10
2 22
2 37
2 56
6 1
6 16
6 31
cember 31.
s.
- 39-47
- 39-53
- 39-44
- 39-58
- 39-58
- 39-31
- 39-78
s.
-0-02
-0-07
+ 0-03
-o-io
+ 0-02
+ 0-30
-0-16
1871, December 30.
By five double altitudes of the Sun's upper limb, and
five more of the lower limb, taken with the same
instruments and precautions used at Jaffna, the
Chronometer was 5h. 12m. 37'33s. slow when it
shewed 15ft. 15m., corresponding to 20h. 27w. of
Colombo Mean Time.
y Ceti
a Ceti
v Orionis
ju Geminorum
7 Geminorum.
1872, January 2.
By six double altitudes of the Sun's lower limb and
six more of the upper limb, taken as before, the
Chronometer was 5h. 12m, 38'46s. slow when it
shewed 22h. 56m., corresponding to 4ft. 8m-. of
Colombo Mean Time.
Means
4 8
- 39-53
o-ioo
Probable eri
Adopted dai
or of mean correction + 0'024
LOCAL TIME DETERMINATIONS.
Local Sidereal and Mean Time Determinations.
39
MADRAS.
COLOMBO.
Star.
Transit
Clock.
Sidereal
Correction.
Residual
Errors.
Mean Time Chronometer Muston 610.
v Piscium . . .
$ Arietis
67 Ceti
|2 Ceti
1872, J
h. m.
1 35
1 48
2 11
2 22
2 37
3 5
4 49
5 26
5 49
anuary 4.
s.
- 43-36
-43-30
- 43-27
- 43-23
- 43-26
- 43-18
- 43-42
- 43-29
-43-30
s.
+ 0-06
-0-07
-0-02
+ 0-02
o-oo
+ 0-10
- 0-07
+ 0-08
+ 0-09
1872, January 3, 4.
By six double altitudes of the Sun's lower limb, and
six more of the upper limb, taken as before, the
Chronometer shewing 15h. 13m., corresponding to
December 3rd 20h. 26m., and two similar afternoon
sets, at Chronometer time 22h. 24m., correspond-
ing to December 4th Sh. 36m. ; the combined
results gave the Chronometer 5h. 12m. 40s. slow,
when it shewed I8h. 4,8m., corresponding to
December 4th Ih. fm. of Colombo Mean Time.
•y Ceti
5 Arietis
i Aurigce
S Orionis
Betelgeux
Means
3 18
-43-29
0-055
Probable er
Adopted da.
ror of mean correction. ± 0'016
Aldebaran
t Aurigae
1872, J
4 29
4 49
5 1
5 19
5 26
5 30
5 36
5 49
anuary 5.
-44-37
- 44-29
- 44-35
- 44-32
-44-34
- 44-35
- 44-36
- 44-42
i
-0-05
+ 0-04
- o-oi
+ 0-03
+ 0-02
+ 0-01
o-oo
-0-05
1872, January 4, 5.
By twenty-four double altitudes of the Sun, taken
about the same times before and after noon as
yesterday, the Chronometer was 5h. 12m. 41'lOs.
slow, when it shewed 18h. 48m., corresponding to
December 5th Oh. 1m. of Colombo Mean Time.
e Leporis
/} Tauri ...
8 Orionis.
e Orionis
a Columbse...
Betelgeux
1872, January 5, 6.
By twenty-four double altitudes of the Sun, taken
before and after noon as on the two previous days,
the Chronometer was 5h. 12m. 41'94s. slow, when it
shewed 18h. 48m., corresponding to December 6th
Oh. 1m. of Colombo Mean Time.
Mean
5 15
-44-35
0-026
Probable ei
Adopted da
•ror of mean correction ± 0*008
40 TELEGRAPHIC LONGITUDE DETERMINATIONS IN INDIA.
Madras and Colombo Time Corrections, 1871, December 31.
At 4h. 8m. by the Madras Transit Clock, it was 39'53 seconds fast of Sidereal Time, with an adopted daily
rate of 0'93 second gaining.
At 3/i. 59m. by Captain Tupman's Chronometer, Muston 610, it was 57i. 12m. 37'59s. slow of Colombo Mean
Time, with an adopted daily rate of 0'49 second losing.
Hence at 4h. 39m. by the Madras Transit Clock, the relative correction was 8m. 3'87s. and its
change — 0*16481 second per minnte.
Telegraphic Signals from Colombo to Madras, 1871, December 31.
Madras
Eecords.
Colombo
Signals.
Difference.
Col.— Mad.
Relative
Correction.
Colombo
West.
Residual
Errors.
h. m. s.
h. m. s.
m. s.
m. s.
TO. S.
s.
3 51 40-7
51 55-5
3 58 15
58 30
6 34-3
6 34-5
8 11-67
8 11-63
1 37-37
1 37-13
+ 0-10
- 0-14*
52 10-7
58 45
6 34-3
8 11-59
1 37-29
+ 0-02
52 41-0
59 15
6 34-0
8 11-50
1 37-50
+ 0-23
53 11-0
59 45
6 34-0
8 11-42
1 37'42
+ 0-15
53 41-0
4 0 15
6 34-0
8 11"34
1 37-34
+ 0-07
53 56-0
0 30
6 34-0
8 11-30
1 37-30
+ 0-03
54 ll'l
0 45
6 33-9
8 11-25
1 37-35
+ 0-08
54 41-0
1 15
6 34-0
8 11-17
1 37-17
-o-io
54 56-1
1 30
6 33-9
8 11-13
1 37'23
- 0-04
55 31-1
1 45
6 33-9
8 11-09
1 37-19
- 0-08
55 41-2
2 15
6 33-8
8 11-01
1 37-21
- 0-06
55 56-2
2. 30
6 33-8
8 10-97
1 37-17
-o-io
56 11-3
2 45
6 337
8 10-93
1 37-23
- 0-04
56 41-4
3 15
6 33-6
8 10-84
1 37-24
. - 0-03
57 11-5
3 45
6 33-5
8 10-76
1 37-26
-o-oi
57 41-5
4 15
6 33-5
8 10-68
1 37-18
- 0-09
58 417
5 15
6 33-3
8 10-51
1 37-21
- 0-06
58 57-0
5 30
6 33-0
8 10-47
1 37-47
+ 0-20
59 12-0
5 45
6 33-0
8 10-43
1 37-43
+ 0-16
59 42-0
6 15
6 33-0
8 10-35
1 37-35
+ 0-08
4 0 12'0
6 45
6 33'0
8 10-26
1 37-26
- o-oi
0 42-0
7 15
6 33-0
8 10-18
1 37-18
-0-09
0 57'2
1 12-1
7 30
7 45
6 32-8
6 32-9
8 10-14
8 10-10
1 37-34
1 37-20
+ 0-07
-0-07
4 1 27-0
480
6 33-0
8 10-06
1 37-06
-0-21
3 56 29-28
4 3 2-88
6 33-60
8 10-87
1 37-27
0-089
TELEGRAPHIC SIGNALS. 41
Telegraphic Signals from Madras to Colombo, 1871, December 31.
Madras
Colombo
Difference.
Eelative
Colombo
Residual
Signals.
Records.
Col.— Mad.
Correction.
West.
Errors.
h. in. s.
h. m. s.
TO. S.
m,. s.
m. s.
s.
4 30 0
4 36 28-0
6 28-0
8 5-35
1 37-35
+ 0-31
30 15
36 43-5
6 28-5
8 5-31
1 36-81
- 0-23
30 30
36 58-2
6 28-2
8 5-27
1 37'07
+ 0-03
30 45
37 13-2
6 .28-2
8 5-23
1 37-03
- o-oi
31 15
37 43-1
6 28-1
8 5-15
1 37-05
+ 0-01
31 30
37 58-1
6 28-1
8 5-11
1 37-01
- 0-03
3L 45
38 13-1
6 28-1
8 5-07
1 36-97
- 0-07
36 15
42 42'2
6 27-2
8 4-32
1 37-12
+ 0-08
36 30
42 57-4
6 27-4
8 4-28
1 36-88
- 0-16
36 45
43 12-3
6 27-3
8 4-24
1 36-94
- o-io
37 15
43 42-1
6 27-1
8 4-16
1 37-06
+ 0-02
37 30
43 57-1
6 27-1
8 4-12
1 37-02
- 0-02
37 45
44 12'1
6 27-1
8 4-08
1 36-98
- 0-06
38 15 -
44 42-1
6 27-1
8 3-99
1 36-89
- 0-15
38 30
.44 57-0
6 27-0
8 3-95
1 36-95
- 0-09
38 45
45 12-0
6 27-0
8 3-91
1 36-91
- 0-13
39 15
45 41-8
6 26-8
8 3-83
1 37-03
- o-oi
39 30
45 567
6 26-7
8 3-79
1 37-09
+ 0-05
560
5 12 22-5
6 22-5
7 59-42
1 36-92
- 0-12
6 15
12 37-2
6 22-2
7 59-38
1 37-18
+ 0-14
6 30
12 52-3
6 22-3
7 59-34
1 37-04
o-oo
6 45
13 7-1
6 22-1
7 59-30
1 37-20
+ 0-16
7 15
13 37-1
6 22-1
7 59-21
1 37-11
+ 0-07
7 30
13 52-1
6 22-1
7 59-17
1 37-07
+ 0-03
8 15
14 37*0
6 22-0
7 59-05
1 37-05
+ 0-01
8 30
14 52-0
6 22-0
7 59-01
1 37-01
- 0-03
8 45
15 7-0
6 22-0
7 58-97
1 36-97
- 0-07
9 15
15 36-6
6 21-6
7 58-88
1 37*28
+ 0-24
9 30
15 517
6 217
7 58-84
1 37-14
. + o-io
5 9 45
5 16 67
6 21-7
7 58'80
1 37-10
+ 0-06
4 48 13-00
4 54 38-31
6 25-31
8 2-35
1 37-04
0-079
11
42
TELEGRAPHIC LONGITUDE DETERMINATIONS IN INDIA.
Madras and Colombo Time Corrections, 1872, January 4.
At 3h. 18m. by the Madras Transit Clock, it was 43 '29 seconds fast of Sidereal Time, with an adopted daily
rate of 0'91 second gaining.
At 3h. 54m. by Captain Tupman's Chronometer, Muston 610, it was 5h. 12m. 40'57s. slow of Colombo Mean
Time, with an adopted daily rate of 0'85 second losing.
Hence at 47i. 1m. by the Madras Transit Clock, the relative correction was 7m. 40' 7s. and its
change + 0'16505 second per minute.
Telegraphic Signals from Colombo to Madras, 1872, January 4.
Madras
Kecords.
Colombo
Signals.
Difference.
Col.— Mad.
Relative
Correction.
Colombo
West.
Residual
Errors.
h. m. s.
h. m. s.
W. S.
m. s.
m. s.
s.
3 51 31-3
3 42 15
9 16-3
7 38-71
I 37-59
- 0-16
51 46-2
52 1-2
42 30
42 45
9 16-2
9 16-2
7 38-75
7 38-79
1 37-45
1 37-41
- 0-30
- 0-34*
52 31-6
43 15
9 16-6
7 38-87
1 37-73
- 0-02
52 46'6
43 30
9 16-6
7 38-91
1 37-69
- 0-06
53 1-9
43 45
9 16-9
7 38-95
1 37-95
+ 0-20
53 32-0
44 15
9 17-0
7 39-04
1 37-96 ,
+ 0-21
53 47-0
44 30
9 17-0
• 7 39-08
1 37-92
+ 0-17
54 2-0
44 45
9 17-0
7 39-12
1 37-88
+ 0-13
54 32-0
45 15
9 17-0
7 39-20
1 37-80
+ 0-05
54 47-1
45 30
9 17-1
7 39-24
1 37-86
+ 0-11
55 2-0
45 45
9 17-0
7 39-28
1 37-72
- 0-03
55 32-1
46 15
9 17-1
7 39-37
1 37-73
- 0-02
55 47-2
46 30
9 17*2
7 39-41
1 37-79
+ 0-04
56 2-1
46 45
9 17-1
7 39-45
1 37-65
-o-io
56 32-3
47 15-
9 17-3
7 39-53
1 37-77
+ 0-02
56 47-2
47 30
9 17-2
7 39-57 .
1 37-63
- 0-12
57 2-4
47 45
9 17-4
7 39-62
1 37-78
+ 0-03
57 32-4
48 15
9 17-4
7 39-70
1 37-70
- 0-05
' 57 47'4
48 30
9 17-4
7 39-74
1 37-66
-0-09
58 2-5
48 45
9 17-5
7 39-78
1 37-72
- 0-03
58 32-6
49 15
9 17-6
7 39-86
1 37-74
- o-oi
58 477
49 30
9 17-7
7 39-91
1 37-79
+ 0-04
59 2'5
49 45
9 17-5
7 39-95
1 37-55
- 0-20
59 33-0
50 15
9 18-0
7 40-03
1 37-97
+ 0-22
59 47'9
50 30
9 17-9
7 40-07
1 37-83
+ 0-08
4 0 3-0
50 45
9 18-0
7 40-11
1 37-89
+ 0-14
0 33-0
51 15
9 18-0
7 40-20
1 37-80
+ 0-05
0 48-0
51 30
9 18-0
7 40-24
1 37-76
+ 0-01
4 1 3-1
3 51 45
9 18-1
7 40-28
1 37-82
+ 0-07
3 56 17-24
3 47 O'OO
9 17-24
7 39-49
1 37-75
0-103
TELEGRAPHIC SIGNALS.
Telegraphic Signals from Madras to Colombo, 1872, January 4.
43
Madras
Signals.
Colombo
Records.
Difference.
Col.— Mad.
Relative
Correction.
Colombo
West.
Residual
Errors.
h. in. s.
. h. m. s.
TO. S.
TO. S.
TO. S.
s.
440
3 54 41-8
9 18"2
7 40-77
1 37-43
-0-09
4 15
54 56-7
9 18-3
7 40-81
1 37-49
- 0-03
4 30
55 11-7
9 18-3
7 40-85
1 37-45
-0-07
4 45
55 26-6
9 18-4
7 40-89
1 37-51
-o-oi
5 15
55 56-6'
9 18-4
7 40-97
1 37-43
-0-09
5 30
56 11-5
9 18-5
7 41-01
1 37-49
-0-03
5 45
56 26-5
9 18'5
7 41-05
1 37-45
-0-07
6 15
56 56-4
9 18-6
7 41-14
1 37-46
- 0-06
6 30
57 11-2
9 18-8
7 41-18
1 37-62
+ 0-10
6 45
57 26-2
9 18-8
7 41-22
1 37-58
-f 0-06
7 15
57 56-1 <
9 18-9
7 41-30
1 37-60
+ 0-08
7 30 '
58 11-1
9 18-9
7 41-34
1 37-56
+ 0-04
7 45
58 26-0
9 19-0
7 41-38
1 37-62
+ 0-10
8 15
58 56-0
9 19-0
7 41-47
1 37-53
+ 0-01
8 30
59 11-0
9 19-0
. 7 41-51
1 37-49
-0-03
8 45
59 26-0
9 19-0
7 41-55
1 37-45
- 0-07
9 15
59 55-9
9 19-1
7 41-63
1 37-47
- 0-05
9 30
4 0 10'8
9 19-2
7 41-67
1 37-53
+ 0-01
9 45
0 25'7
9 19-3
7 41-71
1 37-59
+ 0-07
10 15
0 55'6
9 19-4
7 41-80
1 37-60
+ 0-08
10 30
1 10-6
9 19-4
7 41-84
1 37-56
+ 0-04
10 45
1 25-6
9 19-4
7 41-88
1 37-52
o-oo
11 15
1 55-5
9 19-5
7 41-96
1 37-54
+ 0-02
11 30
2 10-5
9 19-5
7 42-00
1 37-50
-0-02
11 45
2 25-5
9 19-5
7 42-04
1 37-46
-0-06
12 15
2 55-4
9 19-6
7 42-13
1 37-47
-0-05
12 30
3 10-4
9 19-6
7 42-17
1 37-43
-0-09
12 45
3 25-2
9 19-8
7 42-21
1 37-59
-f 0-07
13 15
3 55-1
9 19-9
7 42-29
1 37-61
-f-0-09
13 30
4 10-1
9 19-9
7 42-33
1 37-57
+ 0-05
4 13 45
4 4 25-1
9 19-9
7 42-37
1 37-53
+ 0-01
4 8 50-32
3 59 31-24
9 19-08
7 41-56
1 37-52
0-053
44 TELEGRAPHIC LONGITUDE DETERMINATIONS IN INDIA.
Madras and Colombo Time Corrections, 1872, January 5.
At 5h. 15m. by the Madras Transit Clock, it was 44'35 seconds fast of Sidereal Time, with an adopted
daily rate of 0'95 seconds gaining.
At 4/4. 14m. by Captain Tupman's Chronometer, Muston 610, it was 5h. I2m. 41 '43s. slow of Colombo- Mean
Time, with an adopted daily rate of 0-84 second losing.
Hence at 4fo. 45m. by the Madras Transit Clock, the relative correction was llm. 45'27s. and its
change -f- 0 16507 second per minute.
Telegraphic Signals from Colombo to Madras, 1872, Jan. 5.
Madras
Records.
Colombo
Signals.
Difference.
Col. — Mad.
Relative
Correction.
Colombo
West.
Residual
Errors.
h. TO. s.
h. m. s.
TO. S.
TO. S.
TO. S.
s.
3 50 14-0
3 37 0
13 14-0
11 36-23
1 37-77
+ 0-05
50 29-0
37 15
13 14-0
11 36-27
1 37-73
+ 0-01
50 44-0
37 30
13 14-0
11 36-31
1 37-69
- 0-03*
50 59-1
37 45
13 14-1
11 36-35
1 37-75
+ 0-03
51 29-2
38 15
13 14-2
11 36-44
1 37-76
+ 0-04
51 44-1
38 30
13 14-1
11 36-48
1 37-62
- o-io
51 59-3
52 29-4
52 . 44-6
38 45
39 15
39 30
13 14-3
13 14-4
13 14-6
11 36-52
11 36-60
11 36-65
1 37-78
1 37-80
1 37'95
+ 0-06
+ 0-08
+ 0-23
52 59-4
39 46
13 14-4
11 36-69
1 37-71
- o-oi
53 29-5
53 44-5
40 15
40 30
13 14-5
13 14-5
11 36-77
11 36-81
1 37-73
1 37-69
+ 0-01
- 0-03
53 59-6
40 45
13 14-6
11 36-85
1 37-75
+ 0-03
54 44-5
41 30
13 14-5
11 36-97
1 37-53
- 0-19
54 59-5
41 45
13 14-5
11 37-02
1 37-48
- 0-24
55 30-0
42 15
13 15-0
11 37-10
1 37-90
+ 0-18
55 44-9
42 30
13 14*9
11 37-14
1 37-76
+ 0-04
56 0-0
42 45
13 15-0
11 37-18
1 37-82
+ 0-10
56 30-0
43 15
13 15-0
11 37-26
1 37-74
+ 0-02
56 45-0
43 30
13 15-0
11 37-30
1 37-70
- 0-02
57 0-0
43 45
13 15-0
11 37-35
1 37-65
- 0-07
57 30-2
44 15
13 15-2
11 37'43
1 37-77
-f 0-05
.57 45-1
44 30
13 15-1
11 37-47
1 37-63
- 0-09
58 0-2
. 44 45
13 15-2
11 37-51
1 37-69
- 0-03
58 30'4
45 15
13 15-4
11 37-59
1 37-81
+ 0-09
58 45-3
45 30
13 15-3
11 37-64
1 37-66
- 0-06
59 0-3
45 45
13 15-3'
11 37-68
1 37-62
- o-io
59 30-5
46 15
13 15-5
11 37-76
1 37-74
+ 0-02
59 45-5
46 30
13 15-5
11 37-80
1 37-70
- 0-02
4 0 0-5
3 46 45
13 15-5
11 37-84
1 37-66
- 0-06
3 55 6-25
3 41 51-50
13 14-75
11 37-03
1 37-72
0-070
TELEGRAPHIC SIGNALS.
Telegraphic Signals from Madras to Colombo, 1872, January 5.
45
Madras
Colombo
Difference.
Relative
Colombo
Eesidual
Signals.
liecords.
Col.— Mad.
Correction.
West.
Errors.
/(. in. s.
h. m. s.
in. s.
7H. S.
m. s.
s.
420
3 48 44-5
13 15-5
11 38-17
1 37-33
- o-oi
2 15
48 59-5
13 15-5
11 38-21
1 37-29
- 0-05
2 30
49 14-5
13 15-5
11 38-26
1 37-24
- o-io
2 45
49 29-4
13 15-6
11 38-30
1 37-30
- 0-04
3 15
49 59-2
13 15'8
11 38-38
1 37-42
+ 0-08 '
3 30
50 14-1
13 15-9
11 38-42
1 37-48 •
+ 0-14
3 45
50 29-1
13 15-9
11 .38-46
1 37-44
+ 0-10
4 15
50 59-1
13 15-9
11 38-54
1 37-36
+ 0-02
4 30
51 14-1
13 15-9
11 38-58
1 37-32
- 0-02
4 45
51 29-0
13 IG'O
11 38-63
1 37-37
+ 0-03
5 15
51 59-0
13 16-0
11 38-71
1 37-29
- 0-05
5 30
52 14'0
13 1G-0
11 38-75
1 37-25
-0-09
5 45
52 28-9
13 IG'l
11 38-79
1 37-31
- 0-03
G 15
52 58-8
13 16-2
11 38-87
1 37-33
- o-oi
6 30
53 13'7
13 IG'3
11 38-91
1 37-39
+ 0-05
G 45
53 28'6
13 16-4
11 38-96
1 37-44
+ 0-10
7 15
53 58-G
13 16-4
11 39-04
1 37-36
+ 0-02 •
7 45
54 28-5
13 IG'5
11 39-12
1 37-38
+ 0-04
8 15
54 58-5
13 1G-5
11 39-20
1 37-30
- 0-04
8 30
55 13-5
13 16-5
11 39-24
1 37-26
- 0-08
8 45
55 28-4
13 16-G
11 39-29
1 37-31
— 0-03
9 15
55 58-3
13 167
11 39-37
1 37-33
-o-oi
9 30
5G 13-2
13 16-8
11 39-41
1 37-39
+ 0-05
9 45
5G 28-2
13 16-8
11 39-45
1 37-35
+ 0-01
10 15
56 58'1
13 IG'9
11 39-53
1 37-37
+ 0-03
10 30
57 13"!
13 16-9
. 11 39-57
1 37-33
-o-oi
10 45
57 28-0
13 17-0
11 39-62
1 37-38
+ 0-04
11 15
57 58-0
13 17'0
11 39-70
1 37-30
- 0-04
11 30
58 13-0
13 17-0
11 39-74
1 37-26
-0-08
11 45
58 27-9
13 17-1
11 39-78
1 37-32
- 0-02
4 12 0
3 58 42-8
13 17-2
11 39-82
1 37-38
+ 0-04
4 6 59-03
3 53 42-70
13 16-33
il 38-99
1 37-34
0-047
12
TELEGRAPHIC LONGITUDE DETERMINATIONS IN INDIA.
Summary 'of Telegraphic Eesults.
1871-72.
Number of Signals.
Colombo
West.
Probable
Errors.
Compound
Retardation.
in. s.
s.
9.
December 31 ...
» j>
By 26 from Colombo ...
By 30 from Madras
1 37-27
1 37-04
± 0-015
± 0-012
0-115
January 4
5» 5)
By 30 from Colombo
By 31 from Madras
1 37-75
1 37-52
± 0-016
± 0-008
0-115
„ ' 6
5» »
By 30 from Colombo
By 31 from Madras
1 37-72
1 37-34
± 0-011
± 0-007
0-190
*
Final Results.
h. m. s.
Madras Observatory East of Greenwich ... ... 5 20 59'40
Colombo Flagstaff West of Madras 1 37'44
Colombo Flagstaff East of Greenwich 5 19 21 '96
Probable Error of Signals and Madras Transits... ± O020
Retardation. (Current and Instruments.) ... 0'140
KARACHI. 47
KARACHI.
The telegraphic determination of the difference of longitude between
Madras Observatory and Karachi was of two-fold importance and interest,
from its being one of the Indian stations at which observations of the
Transit of Venus, on 1874 December 8th, were arranged to be made ; and
still more as a means of comparison between Madras and Greenwich,
in conjunction with the similar operations by Drs. Becker and Fritsch,
members of the German Transit of Venus Expedition to Ispahan. A
severe test of the accuracy of both determinations is furnished by the
consideration, that the resulting longitude of Madras, as found, via
Karachi, Ispahan and Berlin, is only one-tenth of a second less than that
now adopted from the far more elaborate processes employed by Lieut. -Col,
Campbell and Major Heaviside, R. E., Officers of the Great Trigonometrical
Survey of India, between Madras, Bombay, Aden and Suez, in 1877 ;
combined with those between Suez, Mokattam and Greenwich, by Lord
Lindsay's " Transit of Venus" party in 1874.
The observer and operator at Karachi was General T. Addison, C.B.,
then in command of the Poona Division. His observatory was connect-
ed by triangulation with that of the Great Trigonometrical Survey, on
Bath Island, and the latter was found to be 0*60 second further West of
Madras. Not being aware whether any permanent mark of the site of
General Addison's temporary station was made, I have thought it better
to refer the final result to the G. T. S. Observatory ; the locality of
which is necessarily a definite geographical position in the Survey.
Telegraphic exchanges, of one hundred signals each way, were made on
December 15th, without a single mistake throughout on either side. Both
star transits and telegraphic signals were recorded on the chronograph at
Karachi, and the tape fillets, as well as their tabulated records, were all
in my possession before the end of the month ; mine to General Addison
following early in January. Prompt completion of such works greatly
adds to the interest felt in them by the operators, but is rarely possible in
India. It is surprising, that with only three clock stars at Karachi such
accuracy should have been attained; but limited time and unfavorable
weather prevented General Addison from getting more. As usual, the most
willing aid was rendered at each end by the officers of the Government
Telegraph Department; Mr. W. Williams at Karachi, and Mr. W. F.
Melhuish at Madras,
48 TELEGRAPHIC LONGITUDE DETERMINATIONS IN INDIA.
Local Sidereal Time Determinations, 1874, December 13.
MADRAS.
KARACHI.
Star.
Transit
Clock.
Sidereal
Correction.
Residual
Errors.
Sidereal Time determined by three stars only, viz.,
a Andromeda?, p. Geminorum and S Leonis ; using a
portable Transit Instrument, an electrical clock, and
a tape recording chronograph. No details were
furnished except the interpolated corrections to
clock times of signals, the first and last being :
h. m. s. .-••.
At 4 30 59 .. Correction 4-9-500
0 Ceti
h. m.
1 18
1 25
1 35
1 48
2 0
2 11
2 37
2 56
3 16
3 52
s.
- 10-07
- 9-99
- 10-24
- 10 07
- 9-91
q.q/L
-0-06
+ 0-02
- 0-22
-'0-05
+ 0-12
+ 0-10
- 0-02
- 0-07
-o-oi
+ 0-19
T? Piscium
v Piscium
£ Arietis
a Arietis
•At 5 19 50 Correction....
.... + 9-584 *
07 Ueti
72 Ceti
- 10-07
- 10-13
- 10-08
- 9-90
•
•
a Ceti
71 Eridani....
Means
2 18
- 10-01
0-086
Probable error of mean correction ... ± 0-024
Adopted daily change ... ... ... — 0'83
Comparisons of Madras Clocks and Chronometer.
Transit
Clock.
Sidereal
Correction.
Chronometer
Dent 1668.
Mean Time
Correction.
Shepherd's
ElectricalClock.
Mean Time
Correction.
h. m. s.
s.
1874. h. in. s.
m. s.
h. in. s.
s.
0 49 16
* - 9-99
Dec. 13... 7 22 29'5
- 1 43 '60
„ „ ... 11 24 43-0
- 1 43-88
11 23 0
- 0-88
8 59 17
- 10-27
„ „ ... 15 31 10-5
- 1 44-16
„ „ ... 22 40 43-5
- 1 44-66
22 39 0
- 1-16
TIME CORRECTIONS AND TELEGRAPHIC SIGNALS. 49
Madras and Karachi Time Corrections, 1874, December 13.
At llli. 25m. by Shepherd's Electrical Clock, it was 0'88 second fast of Madras Mean Time, with an
adopted daily rate of 0'60 second gaining.
At 4h. 31m. by General Addison's Transit Clock, it was 9'50 seconds slow of Karachi Sidereal Time
with an adopted daily rate of 2-47 seconds losing.
Hence at 12h. 13m. by Shepherd's Electrical Clock, the relative correction was 6h. 31m. 2-31s. and its
change — 0"16215 second per minute.
Telegraphic Signals from Madras to Karachi, 1874, December 13.
Madras
Signals.
Karachi
Records.
Difference.
Kar. — Mad.
Relative
Correction.
Karachi
West.
Residual
Errors.
h. m. s.
h. m. s.
h. m. s.
h. m. s.
m. s.
s.
11 55 10
55 20
55 30
4 30 59-04
31 9-08
31 19-19
7 24 10-96
24 10-92
24 10-81
6 31 5-20
31 5-17
31 5-15
53 5-76
53 5-75
53 5-66
+ 0-02
+ 0-01
-0-08
55 40
31 29-19
24 10-81
31 5-12
53 5/69
-0-05
55 50
31 39-30
24 10-70
31 5-09
53 5-61
-0-13
56 10
56 20
31 59-18
32 9-33
24 10-82
24 10-67
31 5-04
31 5-01
53 5-78
63 5-66
+ 0-04
-0-08
56 30
32 19-31
24 10-69
31 4-98
53 5-71
-0-03
56 40
32 29-34
24 10-66
31 4-96
53 5-70
-0-04
56 50
32 39-38
24 10-62
31 4-93
53 5-69
-0-05
57 10
32 59-44
24 10-56
31 4-88
53 5-68
-0-06
57 20
33 9-48
24 10-52
31 4-85
53 5-67
-0-07
57 30
33 19-48
24 10-52
31 4-82
53 5-70
-0-04
57 40 '
57 50
33 29-45
33 39-40
24 10-55
24 10-60
31 4-79
31 4-77
53 5-76
53 5-83
+ 0-02
+ 0-09
58 10
58 20
58 30
58 40
58 50
33 59-51
34 9-51
34 19-58
34 2961
34 39-67
24 10-49
24 10-49
24 10-42
24 10-39
24 10-33
31 4-71
31 4-69
31 4-66
31 4-63
31 4-61
53 5-78
53 5-80 .
53 5'76
63- 5-76
53 5-72
+ 0-04
+ 0-06
+ 0-02
+ 0-02
-0-02
59 10
34 5971
24 10-29
31 4-55
53 5-74
o-oo
59 20
35 9-76
24 10-24
31 4-52
53 5-72
-0-02
59 30
59 40
59 50
35 19-71
35 29-76
35 39-78
24 10-29
24 10-24
24 10-22
31 4-50
31 4-47
31 4-44
53 5-79
53 5-77
53 5-78
+ 0-05
+ 0-03
+ 0-04
12 0 10
35 59-87
24 10-13
31 4-39
53 5-74
o-oo
0 20
0 30
12 0 40
36 9-86
36 19-89
4 36 29-96
24 10-14
24 10-11
7 24 10-04
31 4-36
31 4-33
6 31 4-31
53 5-78
53 5-78
53 5-73
+ 0-04
H-0'04
-O'Ol
13
50 TELEGRAPHIC LONGITUDE DETERMINATIONS IN INDIA.
Telegraphic Signals from Madras to Karachi, 1874, December 13.
Madras
Signals.
Karachi
Records .
Difference.
Kar. — Mad.
Relative
Correction.
Karachi
West.
Residual
Errors.
h. m. s.
h. TO. s.
h. m. s.
h. m. s.
TO. S.
s.
12 0 50
4 36 39-96
7 24 10-04
6 31 4-28
53 5-76
+ 0-02
1 10
37 0-01
24 9-99
31 4-23
53 5-76
+ 0-02
1 20
37 10-06
24 9-94
31 4-20
53 5-74
o-oo
1 30
37 20-03
24 9-92
31 4-17
53 5-75
+ 0-01
1 40
37 30-11
24 9-89
31 4-15
53 5-74
o-oo
1 50
37 40-37
24 9-63
31 4-12
53 5-51
-0-23
2 10
38 0-26
24 9-74
31 4-07
53 5-67
-0-07
2 20
38 10-25
24 9-75
31 4-04
53 5-71
-0-03
2 30
2 40
38 20-17
38 30-23
24 9-83
24 9-77
31 4-01
31 3-98
53 5-82
53 5-79
+ 0-08
+ 0-05
2 50
3 10
38 40-23
39 0-38
24 9-77
24 9-62
31 3-96
31 3-90
53 5-81
53 5-72
+ 0-07 *
-0-02
3 20
3 30
3 40
39 1033
39 20-40
39 30-46
24 9-67
24 9-60
24 9-54
31 3-88
31 3-85
31 3-82
53 5-79
53 5-75
53 5-72
+ 0-05
+ 0-01
- 0-02
3 50
4 10
4 20
4 30
4 40
39 40-43
40 0-46
40 10-54
40 20-53
40 30-52
24 9-57
24 9-54
24 9-46
24 9-47
24 9-48
31 3-79
31 3-74
31 3-71
31 3-69
31 3-66
53 5-78
53 5-80
53 5-75
53 5-78
53 5-82
+ 0-04
+ 0-06
+ 0-01
+ 0-04
+ 0-08
4 50
5 10
5 20
40 40-53
41 0-65
41 10-84
24 9-47
24 9-35
24 9-16
31 3-63
31 3-58
31 3-55
53 5-84
53 5-77
53 5-61
+ 0-10
-fO-03
-0-13
5 30
5 40
41 20-72
41 30-81
24 9-28
24 9-19
31 3-52
31 3-50
53 5-76
53 5-69
+ 0-02
-0-05
5 50
41 40-85
24 9-15
31 3-47
53 5-68
-0-06
6 10
42 0-86
24 9-14
31 3-42
53 5-72
-0-02
6 20
42 10-88
24 9-12
31 3-39
53 5-73
-o-oi
6 30
42 20-91
24 9-09
31 3-36
53 5-73
-o-oi
6 40
42 30-93
24 9-07
31 3-34
53 5-73
-o-oi
6 50
42 41-00
24 9-00
31 3-31
53 5-69
-0-05
7 10
43 1-02
24 8-98
31 3-25
53 5-73
-o-oi
7 20
43 11-04
24 8-96
31 3-23
53 5-73
-o-oi
7 30
7 40
43 21-00
43 31-18
24 9-00
24 8-82
31 3-20
31 3-17
53 5-80
53 -5-65
+ 0-06
-0-09
7 50
8 10
12 8 20
43 41-34
44 1-18
4 44 11-23
24 8-66
24 8-82
7 24 8-77
31 3-15
31 3-09
6 31 3-06
53 5-51
53 5-73
53 5-71
-0-23
-0-01
-0-03
TELEGRAPHIC SIGNALS.
Telegraphic Signals from Madras to Karachi, 1874, December 13.
61
Madras
Karachi
Difference.
Relative
Karachi
.Residual
Signals.
Records.
Kar. — Mad.
Correction.
West.
Errors.
h. m. s.
h. m. s.
h. m, s.
h, m. s.
m. s.
s.
12 8 30 .
4 44 21-26
7 24 8-74
6 31 3-04
53 5-70
- 0-04
8 40
44 31-24
24 8-76
31 3-01
53 5-75
+ 0-01
8 50
44 41-31
24 8-69
31 2-98
53 5-71
- 0-03
9 10
45 1-33
24 8-67
31 2-93
53 5-74
o-oo
9 20
45 11-38
24 8-62
31 2-90
53 5-72
-0-02
9 30
45 21-38
24 8-62
31 2-88
53 5-74
o-oo
9 40
45 31-41
24 8-59
31 2-85
53 5-74
o-oo
9 50
45 41-42
24 8-58
31 2-82
53 5-76
+ 0-02
10 10
46 1-46
24 8-54
31 2-77
53 5-77
+ 0-03
10 20
46 11-48
24 8-52
31 2-74
53 5-78
+ 0-04
10 30
46 21-60
24 8-40
31 2-71
53 5-69
-0-05
10 40
46 31-56
24 8-44
31 2-69
53 5-75
+ 0-01
10 50
46 41-56
24 8-44
31 2-66
53 5-78
+ 0-04
11 10
47 1-58
24 8-42
31 2-61
53 5-81
+ 0-07
11 20
47 11-73
24 8-27
31 2-58
53 5-69
-0-05
11 3V)
47 21-67
24 8-33
31 2-55
53 5-78
+ 0-04
11 40
47 31-75
24 8-25
31 2-52
53 5-73
- o-oi
11 50
47 41-74
24 8-26
31 2-50
53 5-76
+ 0-02
12 10
48 1-81
24 8-19
31 2-44
53 575
+ 0-01
12 20
48 11-82
24 8-18
31 2-42
53 5-76
+ 0-02
12 30
48 21-84
24 8-16
31 2-39
53 5-77
+ 0-03
12 40
48 31-89
24 8-11
31 2-36
53 5-75
+ 0-01
12 50
48 41-87
24 8-13
31 2-34
53 579
+ 0-05
13 10
49 1-96
24 8-04
31 2-28
53 5-76
+ 0-02
13 20
49 12-00
24 8-00
31 2-25
53 5-75
+ 0-01
13 30
49 22-00
24 8-00
31 2-23
53 5'77
+ 0-03
13 40
49 32-03
24 7'97
31 2-20
53 5-77
+ 0-03
13 50
49 42-03
24 7-97
31 2-17
53 5-80
+ 0-06
14 10
50 2-12
24 7-88
31 2-12
53 5-76
+ 0-02
14. 20
50 12-16
24 7-84
31 2-09
53 5-75
+ 0-01
14 30
50 22-23
24 7-77
31 2-06
53 5-71
-0-03
14 40
50 32-21
24 7-79
31 2-04
53 5-75
4-0-01
12 14 50
4 50 42-24
7 24 7-76
6 31 2-01
53 5-75
+ 0-01
12 5 O'OO
4 40 50-66
7 24 9-34
6 31 3-60
53 5-74
0-039
52 TELEGRAPHIC LONGITUDE DETERMINATIONS IN INDIA.
Telegraphic Signals from Karachi to Madras, 1874, December 13.
Madras
Records.
Karachi
Signals.
Difference.
Kar. — Mad.
Relative
Correction.
Karachi
West.
Residual
Errors.
h. m. s.
h. m,. s.
7i. m. s.
h. m. s.
m. s.
s.
12 24 17-0
5 0 10-43
7 24 6-57
6 31 0-48
53 6-09
+ 0-13
24 27-0
0 20-42
24 6-58
31 0-45
53 6-13
+ 0-17
24 36-8
0 30-34
24 6-46
31 0-43
53 6-03
+ 0-07
24 46-4
0 40-17
24 6-23
31 0'40
53 5-83
- 0-13
24 57-0
0 50-43
24 6-57
. 31 0-37
53 6-20
+ 0-24
25 16-9
1 10-42
24 6-48
31 0-32
53 6-16
+ 0-20
25 26-5
1 20-34
24 6-16
31 0-29
53 5-87
- 0-09
25 36-5
1 30-19
24 6-31
31 0-27
53 6-04
+ 0-08
25 46-5
1 40-36
24 6-14
31 0-24
53 5-90
- 0-06
25 56-4
1 50-33
24 6-07
31 0-21
53 '5-86
- o-io
26 16-8
2 10-56
24 6-24
31 0-16
53 6-08
+ 0-12*
26 26-3
2 20-33
24 5-97
31 0-13
53 5-84
-0-12
26 36-2
2 30-28
24 5-92
31 0-10
53 5-82
-0-14
26 46-1
2 40-05
24 6-05
31 0-08
53 5-97
+ 0-01
26 56-2
2 50-24
24 5-96
31 0'05
53 5-91
- 0-05
27 16-1
3 10-25
24 5-85
31 O'OO
53 5-85
- 0-11
27 26-1
3 20-25
24 5-85
30 59-97
53 5-88
- 0-08
27 36-1
3 30-32
24 5-78
30 59-94
53 5-84
- 0-12
27 46'0
3 40-14
24 5-86
30 59-92
53 5-94
- 0-02
27 56-0
3 50-18
24 5-82
30 59-89
53 5-93
- 0-03
28 16-1
4 10-30
24 5-80
.30 59-83
53 5-97
+ 0-01
28 26-0
4 20-29
24 5-71
30 59-81
53 5-90
- 0-06
28 36'0
4 30-22
24 5-78
30 59-78
53 6-00
+ 0-04
28 46-1
4 40-32
24 5-78
30 59-75
53 6-03
+ 0-07
28 56-0
4 50-29
24 5-71
30 -59-73
53 5-98
+ 0-02
29 16'0
5 10-29
24 5-71
30 59-67
53 6-04
+ 0-08
29 26-0
5 20-34
24 5-66
30 59-65
53 6-01
+ 0-05
29 36-0
5 30-36
24 5-64
30 59-62
53 6-02
+ 0-06
29 45-9
5 40-18
24 5-72
30 59-59
.53 6-13
+ 0-17
29 55-9
5 50-30
24 5-60
30 59-56
53 6-04
+ 0-08
30 16-0
6 10-36
24 5-64
30 59-51
53 6-13
+ 0-17
30 26-0
6 20-41
24 5-59
30 59-48
53 6-11
+ 0-15
30 35-8
6 30-34
24 5-46
30 59-46
53 6-00
+ 0-04
30 45'8
6 40-38
24 5-42
30 59-43
53 5-99
+ 0-03
30 56-0
6 50-46
24 5-54
30 59-40
53 6-14
+ 0-18
31 15-6
7 10-28
24 5-32
30 59-35
53 5-97
+ 0-01
31 25-6
7 20-28
24 5-32
30 59-32
53 6-00
-{-0-04
12 31 35-5
5 7 30-24
7 24 5-26
6 30 59-29
53 5-97
+ 0-01
TELEGRAPHIC SIGNALS.
Telegraphic Signals from Karachi to Madras 1874, December 13.
Madras
Records.
Karachi
Signals.
Difference.
Kari — Mad.
Relative
Correction.
Karachi
West.
Residual
Errors.
h. m. s.
h. m. s.
h. m. s.
h. m. s.
TO. S.
s.
12 31 45-5
5 7 40*28
7 24 5'22
6 30 59-27
53 5-95
- o-oi
31 55-5
7 50-32
24 5-18
30 59-24
53 5-94
- 0-02
32 15-3
8 10*39
24 4-91
30 59-19
53 5-72
- 0-24
32 25-5
8 20-58
24 4-92
30 59-16
53 5-76
-0-20
32 35-4
8 30-30
24 5-10
30 59'13
53 5-97
H-o-oi
32 45-3
8 40*22
24 5-08
30 59-11
53 5-97
+ 0-01
32 55-4
8 50-29
24 5-11
30 59'08
53 6-03
+ 0-07
33 15-4
9 10-40
24 5-00
30 59-02
53 5-98
+ 0-02
33 25-3
9 20-46
24 4'84
30 59-00
53 5-84
-0-12
33 35-2
9 30-26
24 4-94
30 58-97
53 5-97
+ 0-01
33 45-2
9 40-44
24 4-76
30 58-94
53 5-82
- 0-14
33 55-2
9 50'33
24 4-87
30 58-92
53 5-95
-o-oi
34 15-1
10 10-28
24 4'82
30 58-86
53 5-96
o-oo
34 25-1
10 20'37
24 4-73
30 58-84
53 5-89
-0-07
34 35-0
10 30'27
24 4-73
3.0 58-81
53 5-92
-0-04
34 45-0
10 40-26
24 4-74
30 58-78
53 5-96
o-oo
34 55-0
10 50'38
24 4-62
30 58-76
53 5'86
- o-io
35 15-0
11 10'31
24 4-69
30 58'70
53 5-99
+ 0-03
35 25-0
11 20*30
24 4-70
30 58'67
53 6-03
+ 0-07
35 35-0
11 30-18
24 4-82
30 58'65
53 6'17
+ 0-21
85 44-8
11 40-20
24 4-60
39 58-62
53 5'98
+ 0-02
35 55-0
11 50-25
24 4-75
30 58-59
53 6-16
+ 0-20
36 15-0
12 10-42
24 4-58
30 58-54
53 6-04
+ 0-08
36 24-5
12 20-21
24 4-29
30 58-51
53 5-78
- 0-18
36 34-8
12 30-30
24 4-50
30 58-49
53 6'01
+ 0-05
36 44-7
12 40-23
24 4-47
30 58'46
53 6-01
+ 0-05
36 54-8
12 50-16
24 4-64
30 58-43
53 6'21
+ 0-25
37 14-6
13 10-31
24 4-29
30 58-38
53 5-91
- 0-05
37 24-5
13 20-16
24 4-34
30 58-35
53 5-99
+ 0-03
37 34-4
13 30-21
24 4-19
30 58-32
53 5-87
-0-09
37 44-5
13 40-23
24 4-27
30 58-30
53 5-97
+ 0-01
37 54-5
13 50-38
24 4-12
30 58'27
53 5-85
- 0-11
38 14-4
14 10-40
24 4-00
30 58-22
53 5-78
-0-18
38 24-2
14 20-25
24 3-95
30 58-19
53 5-76
- 0-20
38 34-2
14 30-25
24 3-95
30 58-16
53 5-79
- 0'17
38 44-4
14 40-44
24 3-96
30 58-14
53 5-82
- 0-14
38 54-4
14 50-48
24 3-92
30 58-11
53 5-81
- CK15
• 39 14-2
15 10-26
24 3-94
30 58-06
53 5-88
-0-08
39 24-2
15 20-29
24 3-91
30 58-03
53 5-88
- 0-08
12 39 34-2
5 15 30-34
7 24 3-86
6 30 58-00
53 5-86
- o-io
14
54 TELEGRAPHIC LONGITUDE DETERMINATIONS IN INDIA.
Telegraphic Signals from Karachi to Madras, 1874, December 13.
Madras
Records.
Karachi
Signals.
Difference.
Kar. — Mad.
Relative .
Correction.
Karachi
West.
Residual
Errors.
h. m. s.
h. m. s.
h. TO. s.
h. m. s.
m. s.
s.
12 39 44-2
5 15 40-34
7 24 3-86
6 30 57-97
53 5-89
- 0-07
39 54-1
40 14-1
15 50-16
16 10-27
24 3-94
24 3-83
30 57-95
30 57-89
53 5-99
53 5-94
+ 0-03
- 0-02
40 24-1
40 34-0
16 20-10
16 30-25
24 4-00
24 3-75
30 57-87
30 57-84
53 6-13
53 5-91
+ 0-17
- 0-05
40 44-0
16 40-27
24 3-73
30 57-81
53 5'92
- 0-04
40 54-0
41 14-0
16 50-23
17 10-33
24 3-77
24 3-67
30 57-79
30 57-73
53 5-98
53 5-94
+ 0-02
- 0-02
41 24-1
41 34-0
17 .20-35
17 30-32
24 3-75
24 3-68
30 57-70
30 57-68
53 6-05
53 6-00
+ 0-09
+ 0-04
41 43-9
41 54-0
17 40-27
17 50-24
24 3-63
24 3-76
30 57-65
30 57-62
53 5-98
53 6-14
+ 0-02 *
+ 0-18
42 13-9
42 23-8
42 33-8
18 10-29
18 20-21
18 30-26
24 3-61
24 3-59
24 3-54
30 57-57
30 57-54
30 57-52
53 6-04
53 6*05
53 6-02
+ 0-08
+ 0-09
+ 0-06
42 43-6
18 40-22
24 3-38
30 57-49
53 5-89
- 0-07
42 53-6
18 50-20
24 3-40
30 57-46
53 5-94
- 0-02
43 13:4
19 10-29
24 3-11
30 57-41
53 5-70
-0-26
43 23-5
19 20-27
24 3-23
30 57-38
53 5-85
- 0-11
43 33-6
19 30-32
24 3-38
30 57-35
53 5-93
-0-03
43 43-5
19 40-35
24 3-15
30 57-33
53 5-82
- 0-14
12 43 53-5
5 19 50-19
7 24 3-31
6 30 57-30
53 6-01
+ 0-05
12 34 5-15
5 10 0-30
7 24 4-85
6 30 58-89
53 5-96
0-086
Hence by 100 Telegraphic Signals from Madras, Karachi was West, 53w. 5'74s. ± O'OOSs. and by 100 more
Signals the reverse way, 53m. 5 '96s. ± 0'007».
Final Results.
h.
Madras Observatory East of Greenwich 5
General Addison's Station West of Madras 0
G. T. Survey Observatory West of General Addison's...
G. T, Survey Observatory East of Greenwich 4
Probable Error of Signals and Madras Transits
Retardation (Current and Instruments.)
m.
s.
20
59-40
53
5*85
0-60
27
52-95
+
0-018
0-110
MUDDAPUR. 55
MUDDAPUR.
The determination of the longitude of Muddapur was made at the
request of Professor P. Tacchini, Director of the Observatory of Palermo,
and also of the " Societa degli Spettroscopisti Italiana", in connection with
his observations of the Transit of Venus on December 8th, 1874. Professor
Tacchini, being appointed by the Italian Government to superintend an
expedition to India, to secure observations, chiefly by the newly discovered
spectroscopic method of recording such phenomena, had previously
addressed me in regard to the selection of a suitable and conveniently
accessible station for the purpose, on the eastern coast, between Madras
and Calcutta, at which there would be a probability of fine weather upon
the important occasion ; but unfortunately I .could afford him very little
hope of experiencing such in December anywhere near Madras ; whereupon
he wisely decided upon trying a more northern and inland spot, and
selected Muddapur, a station on the East Indian Railway, 183 miles north-
west of Calcutta.
A telegram from the Professor, two days after the Transit, announced
his more than partial success, although the weather was even there far
from favorable. A letter of the same date also reached me from Calcutta,
on December 17th, from the Consul General for Italy, the late Monsr.
P. Lamouroux; urging co-operation with Professor Tacchini in an early
telegraphic longitude determination between Madras and .Muddapur. Pro-
fessor Tacchini' s definite proposals and conditional arrangements for carry-
ing out the project followed, under date, Muddapur, December 13th,
arriving on the 20th. I replied by telegraph on the 21st, and on Sunday,
December 27th, when the telegraph lines could be spared with least
inconvenience to the daily traffic on the Government line from Madras to
Calcutta, and on the East Indian Railway Company's line from Calcutta to
Muddapur, which had to be temporarily joined through for the purpose,
the signals were successfully exchanged as detailed in the following pages.
Professor Tacchini's notes of his local time corrections and telegraphic
signals were forwarded to me from Calcutta, under date, 1875, January
5th; but I could have wished more details of the former, such as would
have enabled me to give the final probable error of the complete operations,
instead of having to leave the local time errors indeterminate for Muddapur.
Professor Tacchini, accompanied by Professor Vogel, Dr. Antonio
Abetti, and two other gentlemen of the Italian expedition, kindly favored
me with a hurried visit on January 23rd, when passing Madras in the French
Steamer "Meinam." Preliminary results were duly forwarded to ' the
Professor on May 15th following ; differing only from those now given by
the slight change, subsequently deduced, in the personal equation of the
assistant who observed the star transits at the Madras Observatory.
56
LOCAL TIME DETERMINATIONS.
Madras Sidereal Time Determinations.
Name of
Star.
Transit
Clock.
Sidereal
Correction.
Residual
Errors.
Name of
Star.
Transit
Clock.
Sidereal
Corrections.
Residual
Errors.
1874, December 26.
1874, December 28.
Aldebaran
i AurigaD
sLeporis
Rijrel
h. m.
4 29
4 49
5 1
5 9
5 19
5 26
s.
- 21-08
- 20-93
- 21-08
- 20-98
- 20-90
- 21-00
s.
- 0-14
+ 0-02
- 0-12
-0-02
+ 007
- 0-03
a Arietis
67 Ceti . .. .
h. tn.
2 1
2 11
2 22
2 37
2 56
3 5
s.
- 22 44
- 22-44
- 22 37
- 22-62
- 22-41
- 22-46
s.
o-oo
+ 001
+ 0-09
- 0-16
+ 0-06
+ 0-02
|2 Ceti
y Ceti
$ Tauri
5 Orionis
5 Arietis
€ Orionis
5 30
- 20-99
- 0-02
a Colombae....
5 35
- 20-84
+ 0-14
,
Betelgeux
5 49
- 21-03
- 0-04
/it Geminorum
6 16
- 20-90
+ 0-10
Means
5 20
- 20-97
0-070
Means . ...
2 32
- 22-46
0055
Mean Sidereal Correction.
Adopted daily change
.1874, December 26, 227i. 17m - 21'53 + 0'014
.. - 0-79
Muddapur Mean Time Determinations.
No information afforded as to the way in which the local time was f onnd on by what kind of instrument.
Two mean time chronometers were employed, and their corrections being given for noon of each day
at Muddapur, it is most probable that solar altitudes were observed.
The following are the corrections communicated by Professor Tacchini.
Chronometer, Whiffin 343.
h. m. s.
December 25 • + 4 50 52'07
„ 26 + 4 50 48-56
„ 27 + 4 50 44-94
Chronometer, Dent 1937.
h. m. s.
December 26 + 5 13 46'59
27 + 5 13 42-85
Comparisons of Madras Clocks and Chronometer.
Transit
Clock.
Sidereal
Correction.
Chronometer
Carter 337.
Mean Time
Correction.
Shepherd's
Electrical Clock
Mean Time
Correction.
h. m. s.
s.
1874.
h. TO. s.
in. s.
h. m. s.
s.
18 '8 55
- 21-39
Dec. 26
23 47 35-0
- 1 18-67
» „
23 57 47'5
- 1 18 67
23 56 30
- 1-17
23 43 20
- 21-58
„ 27
5 21 5-0
- 1 18-64
TIME CORRECTIONS AND TELEGRAPHIC SIGNALS. 57
Madras and Muddapur Time Corrections, 1874, December 27.
At O/i. Qrn. by Shepherd's Electrical Clcck, it was 1*17 second fast of Madras Mean Time, with an
adopted daily rate of 0'60 second gaining.
At 19/i. 9m. by Professor Tacchini's Chronometer, Whiffin 343, it was 47i. 50m. 44'94s. slow of Muddapur
Mean Time, with an adopted daily rate of 3'62 seconds gaining.
Hentfe at 17i. 58m. by Shepherd's Electrical Clock, the relative correction was 4ft. 50m. 45'80s. and its
change — 0'00210 second per minute.
Telegraphic Signals from 'Muddapur to Madras, 1874, December 27.
Madras
Records.
Muddapur
Signals.
Difference.
Mad. — Mud.
Relative
Correction.
Muddapur
East.
Residual
Errors.
— _
s.
h. m. s.
h. m. s.
h. m- s.
h, m. s.
m. s.
I 53 23-9
21 28 0
4 25 23-9
4 50 45-81
25 21-91
+ 0-09
53 33-8
28 10
25 23'8
50 45-81
25 22-01
+ 0-19
53 44-0
28 20
25 24-0
50 45-81
' 25 21-81
- o-oi
53 53-9
'28 30
25 23-9
50 45-81
25 21-91
+ 0-09
54 3'8
28 40
25 23-8
50 45-81
25 22-01
+ 0-19
54 14-0
28 50
25 24-0
50 45-81
25 21-81
-o-oi
54 24-0
29 0
25 24-0
50 45-81
25 21-81
-o-oi
54 44-0
29 20
25 24-0
50 45-81
25 21-81
-•o-oi
54 53-9
29 30
25 23-9
50 45-81
25 21-91
+ 0-09
2 1 34-0
36 10
25 24-0
50 45-79
25 21-79
-0-03
1 44-0
36 20
25 24-0
50 45-79
25 21-79
-0-03
1 53-9
36 30
25 23-9
50 45-79
25 21-89
+ 0-07
2 4-0
36 40
25 24-0
50 45-79
25 21-79
-0-03
2 14-0
36 50
25 24-0
50 45-79
25 21-79
-0-03
2 24-0
37 0
25 24-0
50 45-79
. 25 21-79
-0-03
2 34-0
37 10
25 24-0
50 45-79
25 21-79
-0-03
2 44-0
37 20
25 24 0
50 45-79
25 21-79
-0-03
2 54-0'
37 30
25 24-0
50 4579
25 21-79
-0-03
3 4-0
37 40
25 24-0
50 45-79
25 21-79
-0-03
3 14-0
37 50
25 24-0
50 45-79
25 21-79
-0-03
3 24-0
38 0
25 24-0
50 45-79
25 21-79
-0-03
3 33-9
38 10
25 23-9
50 45-79
25 21-89
+ 0-07
3 43-9
38 20
25 23-9
50 45-79
25 21-89
+ 0-07
3 54-0
38 30
25 24-0
50 45-79
25 21-79
-0-03
4 4-0
38 40
25 24-0
50 45-79
25 2179
-0-03
4 14'0
38 50
25 24-0
50 45-79
25 21-79
-0-03
4 24-0
39 0
25 24-0
50 45-79
25 21-79
-0-03
2 4 33-9
21 39 10
4 25 23-9
4 50 45-79
25 21-89
+ 0-07
15
58 TELEGRAPHIC LONGITUDE DETERMINATIONS IN INDIA.
Telegraphic Signals from Muddapur to Madras, 1874, December 27.
Madras
Records.
Muddapur
Signals.
Difference.
Mad. — Mud.
Relative
Correction.
Muddapur
East.
Residual
Errors.
h. m. s.
h. m. s.
h. m. s.
h. m. s.
TO. S.
s.
2 4 43-8
21 39 20
4 25 23-8
4 50 4579
25 21-99
+ 0-17
4 54-0
39 30
25 24-0
50 45-79
25 21-79
- 0-03
5 4-0
39 40
25 24-0
50 45-79
25 21-79
- 0-03
5 14-0
39 50
25 24-0
50 45-78
25 21-78 '
- 0-04
5 23-8
40 0
25 23'8
50 45-78
25 21-98
+ 0-16
5 34-0
40 10
25 24-0
50 45-78
25 21-78
- 0-04
5 43-9
40 20
25 23-9
50 45-78
25 21-88
+ 0-06
6 3-8
40 40
25 23'8
50 45-78
25 21-98
+ 0-16
6 14-0
40 50
25 24'0
50 45-78
25 21-78
- 0-04
6 24-0
41 0
25 24-0
50 45-78
25 21-78
- 0-04
6 34-0
41 10
25 24-0
50 45-78
25 21-78
- 0-04>
6 44-0
41 20
25 24-0
50 45-78
25 21-78
- 0-04
6 539
41 30
55 23-9
50 45-78
25 21-88
+ 0-06
7 • 3-9
41 40
25 23-9
50 45-78
25 21-88
+ 0-06
7 14-0
41 50
25 24-0
50 45-78
25 21-78
- 0-04
7 24-0
42 0
25 24-0
50 45-78
25 21-78
-0-04
7 34-0
42 10
25 24-0
50 45-78
25 21-78
- 0-04
7 44-0
42 20
25 24-0
50 45-78
25 21-78
-0-04
7 54-0
42 30
25 24-0
50 45-78
25 21-78
- 0-04
8 3-9
42 40
25 23-9
50 4578
25 21-88
+ 0-06
8 13'9
42 50
25 23-9
50 45-78
25 21-88
+ 0-06
8 24-0
43 0
25 24-0
50 45-78
25 21-78
- 0-04
8 34-0
43 10
25 24-0
50 45-78
25 21-78
- 0-04
8 44-0
43 20
25 24-0
50 45-78
25 21-78
-0-04
9 3-8
43 40
25 23'8
50 45-78
25 21-98
+ 016
9 14-0
43. 50
25 24-0
50 45-78
25 21-78
- 0-04
9 24-0
44 0
25 24-0
50 45-78
25 21-78
- 0-04
9 34-1
44 10
25 24-1
50 45-78
25 21-68
- 0-14
9 44-0
44 20
25 24-0
50 45-78
25 21-78
-0-04
9 54-0
44 30
25 24-0
50 45-78
25 21-78
-0-04
10 3-8
44 40
25 23-8
50 45-77
25 21-97
+ 0-15
10 14-0
44 50
25 24-0
50 45-77
25 21-77
- 0-05
10 34-0
45 10
25 24-0
50 45-77
25 21-77
-0-05
10 44-0
45 20
25 24-0
50 45-77
25 21-77
- 0-05
10 54-1
45 30
25 24-1
50 45-77
25 21-67
-0-15
11 4-0
45 40
25 24-0
50 4577
25 21-77
- 0-05
11 14-0
45' 50
25 24-0
50 45-77
25 21-77
- 0-05
11 44-0
46 20
25 24-0
50 45-77
25 21-77
-0-05
11 54-0
46 30
25 '24-0
50 45-77
25 21-77
-0-05
2 12 4-0
21 46 40
4 25 24-0
4 50 45-77
25 21-77
- 0-05
TELEaEAPHIO SIGNALS. 59
Telegraphic Signals from Muddapur to Madras, 1874, December 27.
Madras
Kecords.
Muddapur
Signals.
Difference.
Mad. — Mud.
Relative
Correction.
Muddapur
East.
Residual
Errors.
h. m. s.
h. TO. s.
h. m. s.
h. m. s.
TO. S.
s.
2 12 14-0
21 46 50
4 25 24-0
4 50 45-77
25 21-77
- 0-05
12 24-0
47 0
25 24-0
50 45-77
25 21-77
-0-05
2 5 8-25
21 39 44-29
4 25 23-96
4 50 45-78
25 21-82
0-058
Telegraphic Signals from Madras to Muddapur, 1874, December 27.
Madras
Signals.
Muddapur
Records.
Difference.
Mad. — Mad.
Relative
Correction.
Mnddapur
East.
Residual
Errors.
h. TO. s.
h. TO. s.
h. TO. s.
h. TO. s.
TO. S.
s.
2 20 0
21 54 36-3
4 25 23-7
4 50. 45-75
25 22-05
+ 0-13
20 10
54 46-2
25 23-8
50 45-75
25 21-95
+ 0-03
20 20
54 56-4
25 23-6
50 45-75
25 22-15
+ 0-23
20 30
55 6-2
25 23-8
50 45-75
25 21-95
+ 0-03
20 40
55 16-2
25 23-8
50 45-75
25 21-95
+ 0-03
20 50
55 26-1
25 23-9
50 45-75
25 21-85
- 0-07
21 0
55 36-2
25 23-8
50 45-75
25 21-95
+ 0-03
21 ]q
55 46-1
25 23-9
50 45-75
25 21-85
- 0-07
21 20
55 56-1
25 23-9
50 45-75
25 21-85
-0-07
21 30*
56 6-2
25 23-8
50 45-75
25 21-95
+ 0-03
21 40
56 16-0
25 24-0
50 45-75
25 . 21-75
- 0-17
21 50
56 26-3
25 23-7
50 45-75
25 22-05
+ 0-13
22 0
56 36-3
25 23-7
50 45-75
25 22-05
+ 0-13
22 10
56 46-1
25 23-9
50 45-75
25 21-85
- 0-07
22 20
56 56-1
25 23-9
50 45-75
25 21-85
- 0-07
22 30
57 6-4
25 23-9
50 45-75
25 22-15
+ 0-23
22 40
57 16-1
25 23-9
50 45-75
25 21-85
- 0-07
22 50
57 26-0
25 24-0
50 45-75
25 21-75
-0-17
23 0
57 36-3'
25 23-7
50 45-75
25 22-05
+ 0-13
23 10
57 46-3
25 23-7
50 45-75
25 22-05
+ 0-13
23 20
57 56-2
25 23-8
50 45-75
25 21-95
+ 0-03
23 30
58 6-4
25 23-6
50 45-75
25 22:15
+ 023
23 40
58 16-1
25 23-9
50 45-75
25 21-85
-0-07
23 50
58 26-3 '
25 23-7
50 45-75
25 22-05
-f 0-13
2 24 0
21 58 36-1
4 25 23-9
4 50 45-75
25 21-85
-0-07
60 TELEGRAPHIC LONGITUDE DETERMINATIONS IN INDIA.
Telegraphic Signals from Madras to Muddapur, 1874, December 27.
Madras
Muddapur
Difference.
Relative
Muddapur
Residual
Signals.
Records.
Mad.— Mud.
Correction.
East.
Errors .
h. m. s.
h, m: s.
h. m. s.
h. m. s.
m. s.
s.
2 24 10
21 58 46-2
4 25 23-8
4 50 45-75
25 21-95
+ 0-03
24 20
58 56-4
25 23-6
50 45-74
25 22-14
+ 0-22
24 30
59 6-2
25 23-8
50 45-74
25 21-94
+ 0-02
24 40
59 16-0
25 24-0
50 45-74
25 21-74
- 0-18
24 50
59 26-2
25 23-8
50 45-74
25 21-94
-fO'02
25 0
59 36-1
25 23-9
50 45-74
25 21-84
- 0-08
25 10
59 46-1
25 23-9
50 45-74
25 21-84
- 0-08
25 20
59 56-2
25 23-8
50 45-74
25 21-94
+ 0-02
25 30
22 0 6-1
25 23-9
50 45-74
25 21-84
-0-08
25 40
0 16-2
25 23-8
50 45-74
25 21-94
+ 0-02
25 50
0 26-0
25 24-0
50 45-74
25 21-74
- o-ls
26 0
0 361
25 23-9
50 45-74
25 21-84
-0-08
26 10
0 46-2
25 23-8
50 45-74
25 21-94
+ 0-02
26 20
0 56-3
25 23-7
50 45-74
25 22-04
+ 0-12
26 30
1 6-3
25 23-7
50 45-74
25 22-04
+ 0-12
26 40
1 16-3
25 23-7
50 45-74
25 22-04
+ 0-12
26 50
1 26-2
25 23-8
50 45-74
25 21-94
+ 0-02
27 0
1 36-1
25 23-9
50 45-74
25 21-84
-0-08
27 10
1 46-2
25 23-8
50 45-74
25 21-94
+ 0-02
27 20
1 56-2
25 23-8
50 45-74
25 21-94
+ 0-02
27 30
2 6-1
25 23-9
50 45-74
25 21-84
-0-08
27 40
2 16-1
25 23-9
50 45-74
25 21-84
-0-08
28 0
2 36'1
25 23-9
50 45-74
25 21-84
-0-08
28 10
2 46-2
25 23-8
50 45-74
25 21-94-
-f-0'02
28 20
2 56-2
25 23-8
50 45-74
25 21-94
+ 0-02
28 30
3 6-3
25 23-7
50 45-74
25 22-04
+ 0-12
28 40
3 16-3
25 23-7
50 45-74
25 22-04
+ 0-12
28 50
3 26-0
25 24-0
50 45-74
25 21-74
-0-18
29 0
3 36-1
25 23-9
50 45-73
25 . 21-83
- 0-09
29 10
3 46-2
25 23-8
50 45-73
25 21-93
+ 0-01
29 20
3 56-3
25 23-7
50 45-73
25 22-03
+ 0-11
29 30
4 6'3
25 23-7
50 45-73
25 22-03
+ 0-11
29 40
4 16-1
25 23-9
50 45-73
25 21-83
-0-09
29 50
4 26-0
25 24-0
50 45-73
25 21-73 •
- 0-19
2 30 0
22 4 36-1
4 25 23-9
4 50 45-73
25 21-83
- 0-09
2 24 57-17
21 59 33-35
4 25 23-82
4 50 45-74
25 21-92
0-091
. TIME CORRECTIONS AND TELEGRAPHIC SIGNALS.
Madras and Muddapur Time Correctons, 1874, December 27.
61
At Oh. Om. by Shepherd's Electrical Clock it was 1'17 second fast of Madras Mean Time, with an adopted
daily rate of O'GO second gaining.
At 18/i. 4G?n, by Professor Tacchini's Chronometer Dent 1937, it Was 5h. 13m. 42'SSsi slow of Muddapur
Mean Time, with an adopted daily rate of 3'74 seconds gaining*
Hence at 2h> 48m. by Shepherd's Electrical Clock, the Relative Correction was 5h. 13m. 43'59s. and its
change — 0'00218 second per minute.
Telegraphic Signals from Muddapur to Madras, 1874, December 27.
Madras
Records.
Muddapur
Signals.
Difference.
Mad. — Mud.
Relative
Correction.
Muddapur
East.
Residual
Errors.
h> m. s.
h. m* s.
h. m. s.
h. in. 8.
m. s.
s.
2 37 31-1
21 40 10
4 48 21-1
5 13 43-61
25 22-51
+ 0-33
37 41-2
49 20
48 21-2
13 43-61
25 22-41
+ 0-23
37 51-4
49 30
48 21-4
13 43-61
25 22-21
+ 0-03
38 1-4
49 40
48 21-4
13 43-61
25 22-21
+ 0-03
38 21-3
50 0
48 21-3
13 43-61
25 22-31
+ 0-13
38 31-5
50 10
48 21'5
13 43-61
25 22-11
- 0-07
38 51-5
50 30
48 21-5
13 43-61
25 22-11
- 0-07'
43 21-2
55 0
48 21-2
13 43-60
25 22-40
+ 0-22
43 31-2
55 10
48 21-2
13 43-60
25 22-40
+ 0-22
43 41-3
55 20
48 21-3
13 43-60
25 22-30
+ 0-12
43 51-2
55 30
48 21-2
13 43-60
25 22-40
+ 0-22
44 1-4
55 40
48 21-4
13 43-60
25 22-20
+ 0-02
44 11-2
55 50
48 21-2
13 43-60
. 25 22-40
+ 0-22
44 21-5
56 0
48 21-5
13 43'60
25 22-10
- 0-08
44 31-5
56 10
48 21-5
13 43-60
25 22-10
- 0-08
44 41-2
56 20
48 21'2
13 43-60
25 22-40
+ 0-22
44 51-3
56 30
48 21-3
13 43-60
25 22-30
+ 0-12
45 1-2
56 40
48 21-2
13 43-60
25 22-40
+ 0-22
45 ll'l
56 50
48 21-1
13 43-60
25 22-50
+ 0-32
45 21-1
57 0
48 21-1
13 43'60
25 22-50
+ 0-32
45 31-3
57 10
48 21-3
13 43'60
25 22-30
+ 0-12
45 41-3
57 20
48 21-3
13 43-60
25 22-30
+ 0-12
45 51-4
57 30
48 21-4
13 43-59
25 22-19
+ 0-01
46 1-2
57 40
48 21-2
13 43-59
25 22-39
+ 0-21
2 46 11-2
21 57 50
4 48 21-2
5 13 43-59
25 22-39
+ 0-21
16
62 TELEGRAPHIC LONGITUDE DETERMINATIONS IN INDIA.
Telegraphic Signals from Muddapur to Madras, 1874, December 27.
Madras
Eecords.
Muddapur
Signals.
Difference.
Mad. — Mud.
Relative
Correction.
Muddapur
East.
Residual
Errors.
h. TO. s.
h. TO. s.
h. m. s.
h. <m. s.
TO. S.
s.
2 46 21-4
21 58 0
4 48 21-4
5 13 43-59
25 22-19
+ o-oi
46 31-4
58 10
48 21-4
13 43-59
25 22-19
+ 0-01
46 41-6
58 20
48 21-6
13 43-59
25 21-99
- 0-19
46 51-6
58 30
48 21-6
13 43-59
25 21-99
- 0-19
47 1-2
58 40
48 21-2
13* 43-59
25 22-39
+ 0-21
47 11-2
58 50
48 21-2
13 43-59
25 22-39
4-0-21
47 21-4
•59 0
48 21-4
13 43-59
25 22-19
+ 0-01
47- 31-5
59 10
48 21-5
13 43-59
25 22-09
- 0-09
47 41-7
59 20
48 21-7
13 43-59
25 21-89
-0-29
47 51-6
59 30
48 21-6
13 43-59
25 21-99
- 0-19
48 1-6
59 40
48 21-6
13 43-59
25 21-99
- 0-1*)
48 21-6
22 0 0
48 21-6
13 43-59
25 21-99
- 0-19
48 31-6
0 10
48 21-6
13 43-59
25 21-99
- 0-19
48 41-6
0 20
48 21-6
13 43-59
25 21-99
- 0-19
48 51-7
0 30
48 217
13 43-59
25 21-89
-0-29
49 1-8
0 40
48 21-8
13 43-59
25 21-79
- 0-39
49 11-6
0 50
48 21-6
13 43-59
25 21-99
- 0-19
49 21-4
1 0
48 21-4
13 43-59
25 22-19
+ 0-01
49 31-5
1 10
48 21-5
13 43-59
25 22-09
- 0-09
49 41-6
1 20
48 21-6
13 43-59
25 21-99
- 0-19
49 51-6
1 30
48 21-6
13 43-59
25 21-99
- 0-19
50 1-7
1 40
48 21-7
13 43-59
25 21-89
- 0-29
50 11-5
1 50
48 21-5
13 43-59
25 22-09
- 0-09
50 21-4
2 0
48 21-4
13 43-58
25 22-18
o-oo
50 31-5
2 10
48 21-5
13 43-58
25 22-08
- o-io
50 41-3
2 20
48 21-3
13 43-58
25 22-28
+ 0-10
50 51-5
2 30
48 21-5
13 43-58
25 22-08
-o-io
51 1-5
2 40
48 21-5
13 43-58
25 22-08
- o-io
51 11-4
2 50
48 21-4
13 43-58
25 22-18
o-oo
51 21-2
3 0
48 21-2
13 43-58
25 22-38
+ 0-20
51 31-4
3 10
48 21-4
13 43-58
25 22-18
o-oo
51 41-2
3 20
48 21-2
13 43-58
25 22-38
+ 0-20
52 1-2
3 40
48 21-2
13 43-58
25 22-38
+ 0-20
52 11-6
3 50
48 21-6
13 43-58
25 21-98
- 0-20
52 21-2
4 0
48 21-2
13 43-58
25 22-38
+ 0-20
52 31-5
4 10
48 21-5
13 43-58
25 22-08
- o-io
52 41-4
4 20
48 21-4
13 43-58
25 22-18
o-oo
52 51-5
4 30
48 21-5
13 43-58
25 22-08
- o-io
2 53 1-5
22 4 40
4 48 21-5
5 13 43-58
25 22-08
- o-io
TELEGRAPHIC SIGNALS. 63
Telegraphic Signals from Muddapur to Madras, 1874, December 27.
Madras
Records.
Muddapur
Signals.
Difference.
Mad. — Mud.
Relative
Correction.
Muddapur
East.
Residual
Errors.
h. TO. S.
h. m. s.
h. TO. s.
h. m. s.
TO. S.
s.
2 53 11-5
22 4 50
4 48 21'5
5 13 43-58
25 22-08
- o-io
53 21-5
5 0
48 21-5
13 43-58
25 22-08
- o-io
2 47 13-23
21 58 51-82
4 48 21-41
5 13 43-59
25 22-18
0-148
Telegraphic Signals from Madras to Muddapur, 1874, December 27.
Madras
Signals.
Muddapur
Records.
Difference.
Mad.— Mud.
Relative
Correction.
Muddapur
East.
Residual
Errors.
h. m. s.
h. m. s.
h. mi. s.
h. m. s.
TO. S.
s.
3 0 10
22 11 48-8
4 48 21-2
5 13 43-56
25 22-36
-0-05
0 20
11 58-8
48 21-2
13 43-56
25 22-36
- 0-05
0 30
12 8-9
48 21-1
13 43-56
25 22-46
+ 0-05
0 40
12 18-8
43 21:2
13 43-56
25 22-36
-0-05
0 50
12 29-1
48 20-9
13 43-56
25 22-66
+ 0-25
1 0
12 38'8
48 21-2
13 43-56
25 2236
- 0-05
1 10
12 49-0
48 21-0
13 43-56
25 22-56
+ 0-15
1 20
12^59-1
48 20-9
13 43-56
25 22-66
+ 0-25
1 30
13* 8-9
43 21-1
13 43-56
25 22-46
+ 0-05
1 40
13 19-0
48 21-0
13 43-56
25 22-56
+ 0-15
1 50
13 28-9
48 21-1
13 43-56
25 22-46
+ 0-05
2 0
13 39-0
48 21-0
13 43-56
25 22-56
+ 0-15
2 10
13 49-0
48 21-0
13 43-56
25 22-56
+ 0-15
2 20
13 58-9
48 21-1
13 43-56
25 22-46
+ 0-05
2 30
14 9-2
48 20'8
13 43-56
25 22-76
+ 0-35
2 40
14 18-8
48 21-2
13 43-56
25 22-36
- 0-05
2 50
14 28-9
48 21-1
13 43-56
25 22-46
+ 0-05
3 0
14 39-0
48 21-0
13 43-56
25 22-56
+ 0-15
3 10
14 48-9
48 21-1
13 43-56
25 22-46
-I-0-05
3 20
14 58-9
48 21-1
13 43-56
25 22-46
+ 0-05
3 30
15 8-8
48 21-2
13 43-56
25 22-36
- 0-05
3 40
15 18-8
48 21-2
13 43-56
25 22-36
-0-05
3 50
15 28-8
48 21-2
13 43-56
25 22-36
- 0-05
4 0
15 39-1
48 20-9
13 43-56
25 22-66
+ 0-25
4 10
15 49-1
48 20-9
13 43-55
25 22-65
+ 0-24
3 4 20
22 15 59-1
4 48 20-9
5 13 43-55
25 22-65
+ 0-24
64 TELEGRAPHIC LONGITUDE DETERMINATIONS IN INDIA.
Telegraphic Signals from Madras to Muddapur, 1874, December 27,
Madras
Signals.
Muddapur
Kecords.
Difference.
Mad. — Mud.
Relative
Correction,
Muddapur
West,
Residual
Errors.
h. in. s.
h. m. s.
h. m. s.
h. in. s.
m. s.
s.
3 4 30
22 16 9-0
4 48 21-0
5 13 43-55
25 22'55
-t-0'14
4 40
16 19-1
48 20-9
13 43-55
25 22-65
+ 0-24
4 50
16 29-0
48 21-0
13 43'55
25 22-55
+ 0-14
5 0
16 38-9
48 21-1
13 43-55
25 22-45
+ 0-04
5 10
16 48-9
43 21-1
13 43-55
25 22-45
+ 0-04
5 20
16 59-1
48 209
13 43-55
25 22-65
+ 0-24
5 30
17 8-7
48 21-3
13 43-55
25 22-25
- 0-16
5 40
17 19-1
48 20-9
13 43-55
25 22-65
+ 0-24
5 50
17 28-9
48 21-1
13 43-55
25 22-45
+ 0-04
6 0
17 38-9
48 21-1
13 43-55
25 22-45
+ 0-04
6 10
17 48-8
48 21-2
13 43-55
25 22-35
- o-o3
6 20
17 58-8
48 21-2
13 43-55
25 22-35
- 0-OG
6 30
18 8-7
48 21-3
13 43-55
25 22-25
- 0-16
6 40
18 18-8
48 21-2
13 43-55
25 22-35
- 0-06
6 50
18 28-6
48 21-4
13 43-55
25 22-15
- 0-26
7 0
18 38-6
48 21'4
13 43-55
25 22-15
- 0-26
7 10
18 48-7
48 21-3
13 43-55
25 22-25
- 0-16
7 20
18 58-7
48 21-3
13 43-55
25 22-25
- 0-16
7 30
19 8-6
48 21-4
13 43-55
25 22-15
- 0-26
7 40
19 18-7
48 21-3
13 43-55
25 22-25
- 0-16
7 50
19 28-7
48 21-3
13 43-55
25 22-25
-0-16
' 8 0
19 38-7
48 21-3
13 43-55
25 22-25
- 0-16
8 10
19 48-7
48 21-3
13 43-55
25 22-25
-0-16
8 20
19 58-9
48 21-1
13 43-55
25 22-45
+ 0-04
8 30
20 8-9
48 21'1
13 43-55
25 22-45
+ 0-04
8 40
20 18-8
48 21-2
13 43-54
25 22-34
-0-07
8 50
20 28-8
48 21-2
13 43-54
25 22-34
-' 0-07
9 0
20 38-7
48 21-3
13 43-54
25 22-24
- 0-17
9 10
20 48-7
48 21-3
13 43-54
25 22-24
- 0-17
9 20
20 58'9
48 21-1
13 43-54
25 22-44
-j-0-03
9 30
21 8'8
48 21-2
13 43-54
25 22-34
- 0-07
9 40
21 18-7
48 21-3
13 43-54
25 22-24
-0-17
9 50
21 28-7
48 21-3
13 43-54
25 22-24
-0-17
3 10 0
22 21 38-7
4 48 21-3
5 13 43-54
25 22-24
- 0-17
3 5 5-00
22 16 43-86
4 48 21-14
5 13 43-55
25 22-41
0-127
TELEGRAPHIC EESULTS.
Summary of Telegraphic Results.
65
Number of Signals.
Muddapur
East.
Probable
Errors.
Compound
Retardation.
TO. S.
s.
s.
By 70 from Muddapur
By 60 from Madras
25 21-82
25 21-92
± 0-006
± o-oio
0-050
By 66 from Muddapur ... ... ...
By 60 from Madras
25 22-18
25 22-41
± 0-015
± 0-014
0-115
Final Results.
Madras Observatory East of Greenwich.
Muddapur East of Madras. ...
Muddapur East of Greenwich.
Probable Error of Signals and Madras Transits
Compound Retardation. (Current and Instruments.),
h. m. s.
5 20 59-40
25 22-08
5 46 21-48
± 0-018
0-082
17
66 TELEGEAPHIC LONGITUDE DETERMINATIONS IN INDIA.
ROORKEE.
The last telegraphic determination called for was also required in
connection with the Transit of Venus, in December, 1874. Lieut. Col.
J. F. Tennant, R. E., having secured successful observations of the Transit
at Roorkee, desired my co-operation in settling his longitude by means of
telegraphic signals soon after the event as usual, and was promised all needful
aid therein. To my surprise and regret however, as the time for carrying
out the work approached, I discovered that Col. Tennant's idea of co-opera-
tion differed so widely from mine that there seemed little chance of the
work being accomplished at all. After much needless delay, a better
understanding was. arrived at through the mediation of our esteemed
mutual friend, Captain W. M. Campbell, R. E., and the necessary telegraphic
signals were satisfactorily exchanged on three nights, viz., on May 31st,
June 2nd and 5th.
The signals and records at Madras, were given and made by me, as on
the last two occasions, by Shepherd's Electrical Clock, the standard of mean
time for all India ; and by Colonel Tennant, at Roorkee, with his Sidereal
Transit Clock. A further check upon the work was however independently
obtained on the first two evenings, by Captain Campbell making separate
notes of my first series of taps to Roorkee and of Colonel Tennant's first
series therefrom. A third check was also secured on all three nights, by
the record of Col. Tennant's second series of signals from Roorkee upon
the Madras Chronograph,, thanks to Captain Campbell's valuable and oblig-
ing assistance in the working of the instrument while I was otherwise
engaged.
As Captain Campbell, when reading the times of my taps to Roorkee,
only differed O'l second from me in one out of the thirty-six signals
he recorded, and as the fifty- seven Madras signals compared with the
fifty-four from Roorkee, marked on the Madras Chronograph, have been
given in detail, I have not thought it necessary to print the times of each
separate signal in the two checks, but have shewn the mean results of
each series, given and received, for comparison with the similar results
of my own records, which were made by eye and ear throughout. It
will be seen that Captain Campbell's independent records, by eye and ear,
gave a final longitude of Roorkee only 0*03 second greater than my own,
while the chronographic process yielded a result O05 second less.
LOCAL TIME DETERMINATIONS.
67
Advantage was taken of Captain Campbell's presence, to compare his
personal equation for star transits, relatively to my own and those of the
native assistants who made most of the transit observations for finding
the Madras time corrections. From these comparisons it followed, that,
had his time observations been used instead of mine, the resulting longi-
tude would have been 0'35 second less than that I have adopted.
Sidereal Time Determinations.
MADRAS.
ROORKEE.
1875, May 31.
1875, May 31.
Star.
Transit
Clock.
Sidereal
Correction.
Residual
Errors.
Roorkee sidereal time was determined by Lieut.-Col.
Tennant, by means of a transit instrument, an
electrical clock and a chronograph. No details were
however furnished, not even as to the number of
stars upon which the result depended.
At 157;.. 27m. by the transit clock its correction was
stated to be + 6*83 seconds and its daily change
— .2'40 seconds.
flVirginis
3 Virginis
TJ Bootis ....
h. m.
13 3
13 28
13 48
13 55
14 26
16 8
16 21
16 36
16 51
17 9
s.
+ 17-23
+ 17-25
+ 17-24
+ 1716
+ 17-36
+ 17-27
+ 17-28
+ 17-43
+ 17-27
+ 17-33
s.
-0-03
-0-02
-0-03
-Oil
+ 0-09
-0-02
-o-oi
+ 0-14
-0-02
+ 0-03
T Virginia.,-..
p Bootis
3 Ophiuchi....
Ant nr cs
5 Herculis
K Ophiuchi....
o Herculis
15 11
+ 17-28
0-050
Probable er
Adopted da
rOr of mean correction ± 0'014
68
TELEGRAPHIC LONGITUDE DETERMINATIONS IN INDIA.
Sidereal Time Determinations.
MADRAS.
ROORKEE.
1875, June 2.
1875, June 2.
Star.
Transit
Clock.
Sidereal
Correction.
Residual
Errors.
*
)8 Corvi. ...
h. m.
12 28
13 3
13 18
13 28
s.
+ 17-32
+ 17-43
+ 17-47
+ 17-47
s.
- 0-14
- 0-02
+ 0-02
+ 0-02
6 Virginis
3 Virginis
i\ Bootis
13 48
+ 17-42
- 0-04
*
T Virginis
Arcturus
p Bootis
13 55
14 10
14 26
16 36
+ 17-46
+ 17-54
+ 17-56
+ 17-58
o-oo
+ 0-08
+ 0-10
+ 0-10
At 157i. 38'5m. by Roorkee transit clock its correc-
tion was stated to be + 3'87 seconds and its daily
change + 0'60 second.
3 Herculis
fiOphiuchi....
Means
17 14
+ 17-33
- 0-16
14 15
+ 17-46
0-068
Probable error of mea
Adopted daily change,
n correction ± 0'019
-j- Q'23
1875,
June 5.
1875, June 5.
£ Corvi
12 28
+ 18'10
o-m
Spica
13 18
_|_ 18'05
fl-flfi
i] Bootis
13 48
_j_ iS'Ol
o-n
T Virginis
ArcturuS.......
p Bootis
e Bootis
13 55
14 10
14 26
14 39
+ 18 10
+ 18-13
+ 18-21
_j_ ig'25
-0-02
+ 0-01
+ 0-09
4- 0-13
TIME DETERMINATIONS AND COMPAEISONS.
69
MADRAS.
ROORKEE.
1875, June 5 — continued.
1875, June 5 — continued.
Star.
Transit
Clock.
Sidereal
Correction.
Eesidual
Errors.
At 15/i. 49-2m. by Roorkee transit clock, its correction
was stated to have been -j- 5'18 seconds and its
daily change -(- I'OO second.
os Librae
h. in.
• 14 44
14 59
15 58
s.
+ 18-10
+ 18-21
- 18-05
s.
- 0-02
+ 0-09
-0-08
/81 Scorpii
•
Means
14 15
+ 18-12
0-062
Probable error of mean correction ... ± 0'0l7
Adopted daily change ... ... ... + 0'14
Comparisons of Madras Clocks and Chronometer.
Transit
Clock.
Sidereal
Correction.
Chronometer
Carter 703.
Mean Time
Correction.
Shepherd's
ElectricalClock.
Mean Time
Correction.
h. TO. s.
s.
1874. h. m. s.
s.
Ti. in. s.
s.
16 54 53
+ 17-29
May 31... 12 20 lO'O
- 26-91
„ „ ... 12 33 26-5
- 26-85
12 33 0
- 0-35
„ „ ... 16 10 26-0
- 25-94
16 10 0
-j-0-06
20 53 6
+ 17-32
„ „ ... 16 17 43-0
- 25-91
16 47 12
+ 17-48
June 2 ... 12 4 27'0
- 15-29
„ „ ... 12 10 14-5
- 15-26
12 10 0
-076
„ „ ... 14 18 14-0
- 14-70
14 18 0
- 0-70
19 10 2
+ 17-51
„ „ ... 14 26 53-0
- 14-66
16 23 49
+ 18-13
„ 5 ... 11 29 3-0
+ 2-45
„ „ ... 11 33 56-5
+ 2-47
11 34 0
- 1-03
„ „ ... 15 54 55-5
+ 3-42
15 55 0
- 1-08
21 4 37
+ 18-16
„ „ ... 16 9 4-0
H- 3-47
18
70
TELEGRAPHIC LONGITUDE DETERMINATIONS IN INDIA.
Madras and Roorkee Time Corrections) 1875, May 31.
At 12/i. 33m. by Shepherd's Electrical Clock, it was 0'3o second fast of Madras Mean Time, with an
adopted daily rate of 2'72 seconds losing.
At 15/i. 27m. by Lieut. Col. Tennant'a Transit Clock, it was 6*83 seconds slow of Roorkee Sidereal
Time, with an adopted daily rate of 2'40 seconds gaining.
Hence at 12/i. 47m. by Shepherd's Electrical Clock, the Relative Correction was 4/i. 35m. 2472s. and its
change + 0" 16783 second per minute.
Telegraphic Signals from Madras to Roorkee, 1875, May 31,
Madras
Signals.
Roorkee
Records.
Difference.
Roor. — Mad.
Relative
Correction.
Roorkee
West.
Residual
Errors.
h. m. s.
h. m. s.
h. m. s.
h. m. s.
m. s.
s.
12 47 0
17 12 58-38
4 25 58-38
4 35 24-72
9 26-34
+ 0-04
47 10
13 8-44
25 58-44
35 24-75
9 26-31
+ 0-01
47 20
13 18-43
25 58-43
35 24-78
9 26-35
+ 0-04
47 30
13 28-50
25 58-50
35 24-80
9 26-30
o-oo
47 40
13 38-51
25 58-51
35 24-83
9 26-32
+ 0-02
47 50
13 48-50
25 58-50
35 24-86
9 26-36
+ 0-06
48 0
13 58-53
25 58-53
35 24-89
9 26-36
+ 0-06
48 10
14 8-55
25 58-55
35 24-92
9 26-37
+ 0-07
48 20
14 18-58
25 58-58
35 24-94
9 26-36
+ 0-06
48 30
14 28-73
25 58-73
35 24-97
9 26-24
-0-06
48 40
14 38-72
25 58-72
35 25-00
9 26-28
-0-02
48 50
14 48-70
25 58-70
35 25-03
9 26-33
+ 0-03
49 0
14 58-76
25 58-76
35 25-06
9 26-30
o-oo
49 20
15 18-88
25 58-88
35 25-11
1 9 26-23
-0-07
49 30
15 28-84
25 58-84
35 2514
9 26-30
o-oo
49 40
15 38-86
25 58-86
35 25-17
9 26-31
+ 0-01
49 50
15 48-90
25 58-90
35 25-19
9 26-29
-o-oi
50 0
15 58-90
25 58-90
35 25-22
9 26-32
+ 0-02
13 12 0
38 2-70
26 2-70
35 28-92
9 26-22
-0-08
12 10
38 12-64
26 2-64
35 28-94
9 2G-30
o-oo
12 20
38 2264
26 2-64
35 28-97
9 26-33
+ 0-03
12 30
38 32-70
26 2-70 '
35 29-00
9 26-30
o-oo
12 40
38 42-76
26 2-76
35 29-03
9 26-27
-0-03
12 50
38 52-80
26 2-80
35 29-06
9 26-26
-0-04
13 13 0
17 39 2-76
4 26 2-76
4 35 29-08
9 26-32
+ 0-02
TELEGRAPHIC SIGNALS. •
Telegraphic Signals from Madras to Roorkee, 1875, May 31,
71
Madras
Signals.
Roorkee
Records.
Difference.
Roor. — Mad.
Relative
Correction.
Roorkee
West.
Residual
Errors.
h. m. s.
h, m. s.
h. m. s.
h. m. s.
in. s.
s.
13 13 10
17 39 12-82
4 26 2-82
4 35 29-11
9 26-29
-o-oi
13 20
39 22-86
26 2-86
35 29-14
9 26-28
-0-02
13 30
39 32-90
26 2-90
95 29-17
9 26-27
-0-03
13 40
39 42-95
. 26 2-95
35 29-20
9 26-25
-0-05
13 50
39 52-87
26 2-87
35 29-22
9 26-35
+ 0-05
14 0
40 2-94
.26 2-94
35 29-25
9 26-31
+ 0-01
14 10
40 12-98
26 2-98
35 29-28
9 26-30
o-oo
14 20
40 23-02
26 3-02
35 29-31
9 26-29
-o-oi
14 .30
40 33-01
26 3-01
35 29-34
9 26-33
. + 0-03
14 40
40 43.06
26 3-06
35 29-36
9 26-30
o-oo
14 50
40 53-09
26 3-09
35 29-39
9 26-30
o-oo
13 15 0
17 41 3.07
4 26 3-07
4 35 29-42
9 26-35
+ 0-05
13 1 19-19
17 27 20-01
4 26 0-82
4 35 27-12
9 26-30
0-028
Telegraphic Signals from EoorJcee to Madras, 1875, May 31.
Madras
Records.
Roorkee
Signals.
Difference.
Roor. — Mad.
Relative
Correction.
Roorkee
West.
Residual
Errors.
h. m. s.
h. m. s.
h. m. s.
h. m. s.
TO. S.
«.
12 53 1-2
17 19 0
4, 25 58-8
4 35 25-73
9 26-93
+ 0-01
53 11-1
19 10
25 58-9
35 25-76
9 26-86
- 0-06
53 21-2
19 20
25 58-8
35 25-79
9 26-99
+ 0-07
53 31-4
19 30
25 58-6
35 ' 25-81
9 27-21
+ 0-29
53 41-4
19 40
25 58-6
35 25-84
9 27-24
+ 0-32
53 51-1 *
19 50
25 58-9
35 25-87
9 26-97
+ 0-05
54 1-0
20 0
25 59-0
35 25-90
9 26-90
- 0-02
54 ll'O
20 10
25 59-0
35 25-93
9 26-93
+ 0-01
54 21-0
20 20
25 59-0
35 25-95
9 26-95
+ 0-03
54 31-0
20 30
25 59-0
35 25-98
9 26-98
+ 0-06
54 41-0
20 40
25 59-0
35 26-01
9 27-01
+ 0-09
54 50-9
20 50
25 59-1
35 26-04
9 26-94
+ 0-02
55 1-0
21 0
25 59-0
35 26-07
9 27-07
+ 0-15
55 10-9
21 10
25 59-1
35 26-09
9 26-99
+ 0-07
12 55 20-9
17 21 20
4 25 59-1
4 35 26-12
9 27-02
+ 0-10
72
TELEGEAPHIO LONGITUDE DETERMINATIONS IN INDIA.
Telegraphic Signals from Roorkee to Madras, 1875, May 31,
Madras
Records.
Roorkee
Signals.
Difference.
Roor. — Mad.
Relative
Correction.
Roorkee
West.
Residual
Errors.
h. TO. s.
h. m. s.
h. m. s.
h. in. s.
7)1. S.
s.
12 55 31-0
17 21 30
4 25 59-0
4 35 26-15
9 27-15
+ 0-23
55 40-8
21 40
25 59-2
35 26-18
9 26-98
+ 0-06
55 50-7
21 50
25 59-3
35 26-20
9 26-90
- 0'02
56 0-7
22 0
25 59-3
35 26-23
9 26-93
+ 0-01
13 17 57-0
44 0
26 3-0
35 29-91
9 26-91
- o-oi
18 7-0
44 10
26 3-0
35 29-94
9 26-94
+ 0-02
18 17-0
44 20
26 3-0
35 29-97
9 26-97
-fO-05
18 27-0
44 30
26 3-0
35 30-00
9 27-00
+ 0-08
18 36-9
44 40
26 3-1
35 30-03
9 26-93
+ 0-01
18 47-0
44 50
26 3-0
35 30-05
9 27-05
+ 0-13
18 56:7
45 0
26 3-3
35 30-08
9 26-78
-o-il
19 6-6
45 10
26 3-4
35 30-11
9 26-71
- 0-21
19 16-6
45 20
26 3-4
35 30-14
9 26-74
- 0-18
19 26-6
45 30
26 3-4
35 30-16
9 26-76
- 0-16
19 36-5
45 40
26 3-5
35 30-19
9 26-69
- 0-23
19 46-6
45 50
26 3-4
35 30-22
9 26-82
- o-io
19 56-5
46 0
26 3-5
35' 30-25
9 26-75
- 0-17
20 6-6
46 10
26 3-4
35 30-28
9 26-88
- 0-04
20 16-5
46 20
26 3-5
35 30-30
9 26-80
- 0-12
20 26-5
46 30
26 3-5
35 30-33
9 26-83
-0-09
20 46-4
46 50
26 3-6
35 30-39
9 26-79
- 0-13
13 20 56-4
17 47 0
4 26 3-6
4 35 30-42
9 26-82
- 010
13 6 3675
17 32 37-84
4 26 1-09
4 35 28-01
9 26-92
0-098
TIME CORRECTIONS AND TELEGRAPHIC SIGNALS.
Madras and RoorJcee Time Corrections, 1875, June 2.
73
At .12/i,. lOra. by Shepherd's Electrical Clock, it was 0'76 second fast of Madras Mean Time, with an
adopted daily rate of 0'68 second losing.
At 15h. 39m. by Lieut. Col. Tennant's Transit Clock, it was 3'87 seconds slow of Roorkee Sidereal Time,
with an adopted daily rate of 0'60 second losing.
Hence at 127i. 19m. by Shepherd's Electrical Clock, the Relative Correction was 4h. 43m. 15'55s. and its
change + 0'16433 second per minute.
Telegraphic Signals from Roorkee to Madras 1875, June 2.
Madras
Records.
Roorkee
Signals.
Difference.
Roor. — Mad.
Relative
Correction.
Roorkee
West.
Residual
Errors.
li. m. s.
h. m. s.
h. TO. s.
h. m. s.
TO. S.
s.
12 13 12-1
16 47 0
4 33 47'9
4 43 14-60
9 26-70
o-oo
13 22-2
47 10
33 47'8
43 14-62
9 26-82
+ 0-12
13 32-0
47 20
33 48-0
43 14-65
9 26-65
- 0-05
13 42-1
47 30
33 47'9
43 14-68
• 9 26-78
+ 0-08
13 52-2
47 40
33 47'8
43 14-71
9 26-91
+ 0-21
14 2-1
47 50
33 47'9
43 14-73
9 26-83
+ 0-13
14 12-0
48 0
33 48-0
43 14-76
9 26-76
+ 0-06
14 22-0
43 10
33 48-0
43 14-79
9 26-79
+ 0-09
14 32-0
48 20
33 48-0
43 14-82
9 26-82
+ 0-12
14 42-0
48 30
33 48-0
43 14-84
9 26-84
+ 0-14
14 52-0
48 40
33 48-0
43 14-87
9 26-87
+ 0-17
15 1-9
48 50
33 48-1
43 14-90
9 26-80
+ 0-10
15 12-0
49 0
33 48-0
43 14-93
9 26-93
+ 0-23
15 21-7
49 10
33 43-3
43 14-95
9 26-65
-0-05
15 31-6
49 20
33 48-4
43 14-98
9 26-58
-0-12
15 41-5
49 30
33 48'5
43 15-01
9 26-51
-0-19
15 51-6
49 40
33 48-4
43 15-03
9 26-63
- 0-07
16 1-6
49 50
33 48-4
43 15-06
9 26-66
- 0-04
16 11-5
50 0
33 48-5
43 15-09
9 26-59
-o-ii
43 7'2
17 17 0
33 52-8
43 19-51
9 26-71
+ 0-01
43 17'1
17 10
33 52-9
43 19-54
9 26-64
-0-06
43 27'0
17 20
33 53-0
43 19-57
9 26-57
- 0-13
43 37-0
17 30
33 53-0
43 19-59
9 26-59
-o-ii
43 47-0
17 40
33 53-0
43 19-62
9 26-62
- 0-08
12 43 57-0
17 17 50
4 33 53-0
4 43 19-65
9 26-65
-0-05
19
74 TELEGRAPHIC LONGITUDE DETERMINATIONS IN INDIA.
Telegraphic Signals from RoorJcee to Madras, 1875_, June 2.
Madras
Records.
Roorkee
Signals.
Difference.
Roor. — Mad.
Relative
Correction.
Roorkee
West.
Residual
Errors.
h. m. s.
h. m. s.
h. m. s.
h. m. s.
m. s.
s.
12 44 7'0
17 18 0
4 33 53-0
4 43 19-68
9 26-68
- 0-02
44 17-0
18 10
33 53-0
43 19-70
9 26-70
o-oo
44 27-0
18 20
33 53-0
43 19-73
9 26-73
+ 0-03
44 37-0
18 30
33 53-0
43 19-76
9 26-76
+ 0-06
44 47-0
18 40
33 53-0
43 19-79
9 26-79
+ 0-09
44 56-8
19 50
33 53-2
43 19-81
9 26-61
- 0-09
45 6-8
19 0
33 53-2
43 19-84
9 26-64
- 0-06
45 16-8
19 10
33 53-2
43 19-87
9 26-67
-0-03
45 26-5
19 20
33 53-5
43 19-89
9 26-39
- 0-31
45 36-6
19 30
33 53-4
43 19-92
9 26-52
- 0-18
45 46-8
19 40
33 53-2
43 19-95
9 26-75
+ 0-05 '
45 56-7
19 50
33 53-3
43 19-98
9 26-68
- 0-02
12 46 6'7
17 20 0
4 33 53-3
4 43 20-00
9 26-70
o-oo
12 29 39-40
17 3 30-00
4 33 50-60
4 43 17-30
9 26-70
0-091
Telegraphic Signals from Madras to RoorJcee, 1875, June 2.
Madras
Signals.
Roorkee
Records.
Difference.
Roor. — Mad.
Relative
Correction.
Roorkee
West.
Residual
Errors.
h. m. s.
ft. m. s.
h. m. s.
h. m. s.
m. s.
s.
12 20 10
16 53 59-56
4 33 49-56
4 43 15-74
9 26-18
o-oo
20 20
54 9-57
33 49-57
43 15-77
9 26-20
+ 0-02
20 30
54 19-65
33 49-65
43 15-80
9 26-15
-0-03
20 40
54 29-57
33 49-57
43 15-82
9 26-25
+ 0-07
20 50
54 39-60
33 49-60
43 15-85
9 26-25
+ 0-07
21 0
54 49-66
33 49-66
43 15-88
9 26-22
+ 0-04
21 10
54 59-68
33 49-68
43 15-91
9 26-23
+ 0-05
21 20
55 9-76
33 49-76
43 15-93
9 26-17
-o-oi
21 30
55 19-76
33 49-76
43 15-96
9 26-20
+ 0-02
21 40
55 29-80
33 49-80
43 15-99
9 26-19
+ 0-01
21 50
55 39-83
33 49-83
43 16-02
9 26-19
+ 0-01
22 0
55 49-81
33 49-81
43 16-04
9 26-23
+ 0-05
22 10
55 59-87
33 49-87
43 16-07
9 26-20
+ 0-02
22 20
56 9-96
33 49-96
43 16-10
9 26-14
-0-04
12 22 30
16 56 19-99
4 33 49-99
4 43 16-12
9 26-13
-0-05
TELEGRAPHIC SIGNALS.
Telegraphic Signals from Madras to Roorkee, 1875, June 2.
75
Madras
Koorkee
Difference.
Relative
Roorkee
Residual
Signals.
Records.
Roor. — Mad.
Correction.
West.
Errors.
h. m. s.
h. TO. s.
h. TO. s.
h. TO. s.
TO. S.
s.
12 22 40
16 56 29-96
4 33 49-96
4 43 16-15
9 26-19
+ 0-01
22 50
56 39-95
33 49-95
43 16-18
9 26-23
+ 0-05
23 0
56 50-04
33 50-04
43 16-21
9 26-17
-o-oi
52 0
17 25 54-78
33 54-78
43 20-97
9 26-19
+ 0-01
52 10
26 4-78
33 54-78
43 21-00
9 26-22
+ 0-04
52 20
26 14-93
33 54-93
43 21-03
9 26-10
-0-08
52 30
26 24-94
33 54-94
43 21-05
9 26-11
-0-07
52 40
26 34-96
33 54-96
43 21-08
9 26-12
-0-06
52 50
26 44-96
33 54-96
43 21-11
9 26-15
-0-03
53 0
26 54-96
33 54-96
43 21-14
9 26-18
o-oo
53 10
27 5-00
33 55-00
43 21-16
9 26-16
-0-02
53 20
27 15-07
33 55-07
43 21-19
9 26-12
-0-06
53 30
27 25-06
33 55-06
43 21-22
9 26-16
-0-02
53 40
27 35-13
33 55-13
43 21-25
9 26-12
-0-06
53 50
27 45-08
33 55-08
43 21-27
9 26-19
+ 0-01
54 0
27 55-10
33 55-10
43 21-30
9 26-20
+ 0-02
54 10
28 5-11
33 55-11
43 21-33
9 26-22
+ 0-04
64 20
28 15-28
33 55-28
43 21-36
9 26-08
-o-io
54 30
28 25-23
33 55-23
43 21-38
9 26-15
-0-03
12 54 40
17 28 35-27
4 33 55-27
4 43 21-41
9 26-14
-0-04
12 37 0-29
17 10 52-62
4 33 52-33
4 43 18-51
9 26-18
0-036
76 TELEGRAPHIC LONGITUDE DETERMINATIONS IN INDIA.
Madras and Roorkee Time Corrections, 1875, June 5.
At lift. 34m. by Shepherd's Electrical Clock, it was 1'03 seconds fast of Madras Mean Time, with an
adopted daily rate of 0'28 second gaining.
At 15ft. 49m. by Lieut. Col. Tennant's Transit Clock, it was 5'18 seconds slow of Roorkee Sidereal Time,
with an adopted daily rate of TOO second losing.
Hence at lift. 51m. by Shepherd's Electrical Clock, the Relative Correction was 4ft. 54m. 59'04s. and its
change + 0*16339 second per minute.
Telegraphic Signals from Madras to Roorlcee, 1875, June 5.
Madras
Signals.
Roorkee
Records.
Difference.
Roor. — Mad.
Relative
Correction.
Roorkee
West.
Residual
Errors.
* •
ft. m. s.
ft. m. s.
ft. TO. S.
ft. TO. S.
m. s.
».
11 49 0
16 34 32-26
4 45 32-26
4 54 58-71
9 26-45
-0-05
' 49 10
34 42-36
45 32-36
54 58-74
9 26-38
- 0-12
49 20
34 52-29
45 32-29
54 58-77
9 26-48
- 0-02
49 30
35 2-33
45 32-33
54 58-79
9 26-46
- 0-04
49 40
35 12-36
45 32-36
54 58-82
9 26-46
-0-04
49 50
35 22-37
45 32-37
54 58-85
9 26-48
- 0-02
50 0
35 32-26
45 32-26
54 58-88
9 26-62
+ 0-12
50 10
35 42-34
45 32-34
54 58-90
9 26-56
+ 0-06
50 20
35 52-48
45 32-48
54 58-93
9 26-45
-0-05
50 30
36 2-59
45 32-59
54 58-96
9 26-37
-0-13
50 40
36 12-51
45 32-51
54 58-99
9 26-48
-0'02
50 50
36 22-54
45 32-54
54 59-01
9 26-47
-0-03
51 0
36 32-57
45 32-57
54 59-04
9 26-47
-0-03
51 10
36 42-59
45 32-59
54 59-07
9 26-48
- 0-02
51 20
36 52-58
45 32-58
54 59-09
9 26-51
+ 0-01
51 30
37 2-63
45 32-63
54 59-12
9 26-49
- o-oi
51 40
37 12-64
45 32-64
54 59-15
9 26-51
+ 0-01
51 50
37 22-63
45 32-63
54 59-18
9 26-55 .
+ 0-05
52 0
37 32-70
45 32'70
54 59-20
9 26-50
o-oo
12 1 0
46 34-16
45 34-16
55 0-67
9 26-51
+ 0-01
1 10
46 44-17
45 34-17
55 0-70
9 26-53
+ 0-03
1 20
46 54-23
45 34-23
55 0-73
9 26-50
o-oo
1 30
47 4-27
45 34-27
55 0-76
9 26-49
-o-oi
1 40
47 14-30
45 34-30
55 0-78
9 26-48
- 0-02
12 1 50
16 47 24-32
4 45 34-32
4 55 0-81
9 26-49
-o-oi
TELEGEAPHIC SIGNALS.
Telegraphic Signals from Madras to Roorkee, 1875, June 5.
77
Madras
Signals.
Roorkee
Eecords.
Difference.
Boor. — Mad.
Relative
Correction.
Roorkee
West.
Residual
Errors.
h. m. s.
h. TO. s.
h. m. s.
h. m. s.
m. s.
s.
12 2 0
2 10
2 20
2 30
2 40
16 47 34-30
47 44-38
47 54-32
48 4-40
48 14-46
4 45 34-30
45 34-38
45 34-32
45 34-40
45 34-46
4 55 0-84
55 0-86
55 0-89
55 0-92
55 0-95
9 26-54
9 26-48
9 26-57
9 26-52
9 26-49
H-0'04
- 0-02
+ 0-07
+ 0-02
- o-oi
2 50
48 24-58
45 34-58
55 0-97
9 26-39
- 0-11
3 0
3 10
3 20
3 30
48 34-46
48 44-47
48 54-54
49 4-56
45 34-46
45 34-47
45 34-54
45 34-56
55 1-00
55 1-03
55 1-05
55 1-08
9 26-54
9 26-56
9 26-51
9 26-52
+ 0-04
+ 0-06
H-o-oi
+ 0-02
3 40
49 14-64
45 34-64
55 1-11
9 26-47
-0-03
3 50
49 24-69
45 34-69
55 1-14
9 26-45
- 0-05
12 4 0
16 49 34-58
4 45 34-58
4 55 1-16
9 26-58
+ 0-08
11 56 30-00
16 42 3-44
4 45 33-44
4 54 59-94
9 26-50
0-039
Telegraphic Signals from Roorkee to Madras, 1875, June 5.
Madras
Records.
Roorkee
Signals.
Difference.
Roor. — Mad.
Relative
Correction.
Roorkee
West.
Residual
Errors.
h. m. s.
h. m. s.
h. m. s.
h. m. s.
TO. S.
s.
11 55 27-0
16 41 0
4 45 33-0
4 54 59-77
9 26-77
- 0-12
55 37-2
41 10
45 32-8
54 59-79
9 26-99
o-oo
55 47-1
41 20
45 32-9
54 59-82
9 26-92
- 0-07
55 57-1
41 30
45 32-9
54 59-85
9 26-95
- 0-04
56 7-0
41 40
45 33-0
54 59-88
9 26-88
- 0-11
56 17-0
41 50
45 33-0
54 59-90
9 26-90
- 0-09
56 27-1
42 0
45 32-9
54 59-93
9 27-03
+ 0-04
56 37-0
42 10
45 33-0
54 59-96
9 26-96
- 0-03
56 47-0
42 20
45 33-0
54 59-98
9 26-98
-o-oi
56 57-0
42 30
45 33-0
55 0-01
9 27-01
+ 0-02
57 7-0
42 40
45 33-0
55 0-04
9 27-04
+ 0-05
57 17-0
42 50
45 33-0
55 0-07
9 27*07
+ 0-08
57 269
43 0
45 33-1
55 0-09
9 26-99
o-oo
57 37-0
43 10
45 33-0
55 0-12
9 27-12
+ 0-13
11 57 47-0
16 43 20
4 45 33-0
4 55 0-15
9 27-15
+ 0-16
20
78
TELEGRAPHIC LONGITUDE DETERMINATIONS IN INDIA.
Telegraphic Signals from Roorkee to Madras, 1875, June 5.
Madras
Records.
Roorkee
Signals.
Difference.
Roor. — Mad.
Relative
Correction.
Roorkee
West.
Residual
Errors.
h. m. s.
h. m. s.
h. in. s.
h. m. s.
m. s.
s.
11 57 57-0
16 43 30
4 45 33-0
4 55 0-17
9 27-17
+ 0-18
58 6-8
43 40
45 33-2
55 0-20
9 27-00
+ 0-01
58 16-6
43 50
45 33-4
55 0-23
9 26-83
- 0-16
58 26-8
44 0
45 33-2
55 0-26
9 27-06
+ 0-07
12 -15 24-0
17 1 0
45 36-0
55 303
9 27-03
+ 0-04
15 34-0
1 10
45 36-0
55 3-05
9 27-05
+ 0-06
15 44-0
1 20
45 36-0
55 3-08
9 27-08
+ 0-09
15 54-0
1 30
45 36-0
55 3-11
9 27-11
+ 0-12
16 4-0
1 40
45 36-0
55 3-13
9 27-13
+ 0-14
16 13-9
1 50
45 36-1
55 3-16
9 27-06
+ 007
16 23-9
. 2 0
45 36-1
55 3-19
9 27-09
+ 0-JJJ
16 339
2 10
45 36-1
55 3-22
9 27-12
+ 0-13
16 43-9
2 20
45 36-1
55 3-24
9 27-14
+ 0-15
16 53-8
2 30
45 36-2
55 3-27
9 27-07
+ 0-08
17 3-6
2 40
45 36-4
55 3-30
9 26-90
- 0-09
17 13-5
2 50
45 36-5
55 3-32
9 26-82
- 0-17
17 23-5
3 0
45 36-5
55 3-35
9 26-85
- 0-14
17 33-5
3 10
45 36-5
55 3-38
. 9 26-88
- 0-11
17 43-4
3 20
45 36-6
55 3-41
9 26-81
- 0-18
17 53-6
3 30
45 36-4
55 3-43
9 27-03
+ 0-04
18 3-4
3 40
45 36-6
55 346
9 26-86
- 0-13
18 13-3
3 50
45 36-7
, 55 3-49
9 26-79
-0-20
12 18 23'4
17 4 0
' 4 45 36-6
4 55 3-51
9 26-91
-0-08
12 6 55-35
16 52 30-00
4 45 34-65
4 55 1-64
9 26-99
0-092
Summary of Telegraphic Results. (Campbell and Tennant.)
1875.
Number of Signals.
Roorkee
West.
Probable
Error.
Compound
Retardation.
m. s.
s.
s.
May 31
,, ,, ...
By 18 from Madras
By 19 from Roorkee
9 26-31
9 26-99
± 0-007
+ 0-017
0-340
June 2
» » ••• ••
By 18 from Roorkee
By 18 from Madras
9 26-78
9 26-20
+ 0 019
± 0-006
0-290
Mean
By 73 Signals
9 2657
+ 0-022
0-315
TELEGRAPHIC RESULTS.
Summary of Telegraphic Results. (Chronographic Records.)
79
1875.
Number of Signals.
Boorkee
West.
Probable
Errors.
Compound
Retardation.
m. s.
s.
s.
May 31
By 19 from Madras
9 26 '30
±0-005
0-335
» »»
By 18 from Boorkee
9 26-97
±0-009
June 2
By 19 from Boorkee
9 26-78
±0-008
0-315
» )>
By 17 from Madras
9 26-15
± 0-009
„ 5
By 19 from Madras
9 26-51
± 0-007
0-330
„ ,,
By 19 from Roorkee
9 27-17
± 0-008
Mean
By 111 Signals
9 26-65
± 0-019
0-327
Adopted Telegraphic Results. (Pogson and Tennant.)
1875.
Number of Signals.
Roorkee
West.
Probable
Errors.
Compound
Retardation.
m. s.
s.
s.
May 31
» »
By 37 from Madras
By 37 from Roorkee
9 26-30
9 26-92
±0-004
± 0-014
0-310
June 2
»> » •••
By 35 from Madras
By 38 from Roorkee
9 26-18
9 26-70
±0-005
± 0-013
0260
„ 5
,, „
By 38*from Madras
By 38 from Roorkee
9 26-50
9 26-99
. ± 0-005
± 0-013
0-245
Final Results.
Madras Observatory East of Greenwich —
Roorkee West of Madras.
Roorkee East of Greenwich.
Probable Error of Signals and Madras Transits ...
Compound Retardation. (Current and Instruments.)
h. m.
5 20
9
5 11
±
s.
59-40
26-60
32-80
0-020
0-272
80
TELEGRAPHIC LONGITUDE DETEEM I NATIONS IN INDIA.
Summary oj Final Results.
Place.
Station.
East
Longitude.
Prob.
Error.
h. m. s.
s.
Karachi
Observatory of the G. T. Survey.
(4 27 52-95 ?)
± 0-024
Avanashi
N. R. Pogson's Transit Pillar ...
5 9 20-35
±0-113
Jrloorkee
Lt.-Col. Tennant's Transit Pillar.
5 11 32-80
± 0-020
Pondicherry ..
Light House
5 19 20-69
± 0-020
Colombo
Government Flagstaff
5 19 21-96
± 0-021
Jaffna
Captain Tupman's Transit Pillar.
5 20 2-00
± 0-020
Muddapur ...
Professor Tacchini's Transit Pillar
5 46 21-48
±0-018
Singapore . . .
Government Flagstaff
6 55 22-96
± o-o^o
Concluding Remarks.
Probable Errors. — It is much to be regretted that for Karachi,
Eoorkee, Muddapur and Singapore, no details of the local time determina-
tions were furnished me by the observers at those stations. In the cases
of Colombo and Jaffna also, although the most complete details were'
supplied to me by Captain Tupman ; his solar altitudes being grouped,
instead of separately worked out, prevented me from deducing the probable
errors of his local time corrections, withont making freslj calculations which
I did not care to undertake. The consequence of these omissions is, that
the probable errors for these six places shew the uncertainty due to the
Madras Time determinations and the telegraphic signals only ; about 0*02
of a second and nearly the same in each case. The relative personal
equations of the observers being unknown, except in one instance, viz.,
Avanashi, the final probable errors given are no guide to the actual
certainty of the results, but serve merely to indicate the approximate
precision attainable, had the proper and necessary precautions of comparing
the habits of observation, or better still of interchanging the observers,
been possible. Some trifling mistakes were inadvertently made in combin-
ing the .probable errors of the time determinations with those of the
CONCLUDING EEMAEKS. 81
telegraphic signals; amounting to O014 second in the case of Jaffna;
Of006 in Karachi and Singapore, and O'OOl in Avanashi and Colombo.
2. Preservation of Stations. — At four of the stations the temporary
pillar used for the Transit or other instrument employed is the sole
reference for the longitude deduced. It is to be hoped that these will
be carefully preserved, as otherwise, all the labor and expense incurred in
the determinations will be lost.
3. Karachi. — The longitude of the Great Trigonometrical Survey
Station at Karachi, as determined by Lieut.-Col. Campbell and Major
Heaviside with their incomparably superior arrangements, carried from
Madras through Bellary and Bombay to Karachi, give the latter station
47?. 28m. 3*62s. East of Greenwich. An error of exactly ten seconds in
General Addison's time determination is the only possible explanation
of this most unexpected difference ; and supposing such to have been made,
it would have a precisely reverse effect upon his determinations of the
difference of longitude between Karachi and Ispahan, and would therefore
be eliminated in the final difference between Greenwich and Madras,
referred to on page 47. "When communicating his longitude results to the
Royal Astronomical Society (Monthly Notices Vol. XXXVIII page 83)
General Addison remarked as follows : — " That for Karachi, has an element
" of doubt in it, inasmuch as I neglected to obtain the pivot error of my
" Transit Instrument. But to whatever extent the pivot error affected the
" result as regards Karachi, the difference between Ispahan and Madras
" remains unaffected, the errors on the East and West sides of Karachi
" correcting each other."
No conceivable " pivot correction" nor any other kind of instrumental
error could account for so large a difference as exactly ten seconds of time ;
so it seems pretty certain that the clock corrections furnished by General
Addison should have been 19'50 seconds instead of 9*50 seconds, as adopted
on page 49, for finding the relative correction of the signals. This would
give the following numbers to be substituted for those in the "Final
Results," on pages 54 and 80 ; bringing our value of the longitude within 0*67
second of that found by the Officers of the G. T. Survey.
h. m. s.
General Addison's Station West of Madras ... 0 52 55*85
G. T. Survey Observatory East of Greenwich ... 4 28 2'95
82 TELEGRAPHIC LONGITUDE DETEMINATIONS IN INDIA.
4. Roorlcee — The longitude of this station, deduced trigonometrically,
was kindly communicated to me by General J. T. Walker R. E., then
Surveyor General of India, in November -1880, as 5h. llm. 33'23s., which
is 0*43 second greater than the telegraphic determination.
Colonel Tennant, in his "Report on the Transit of Venus" page 5,
remarks, for reasons there stated ; — " The geodesical position of Roorkee,
therefore, is not likely to agree with the astronomical determination."
5. Pondicherry. — General J. T. Walker at the same time favored me
with the trigonometrically determined difference of longitude between
Madras and Pondicherry. Applied to the now adopted longitude of
Madras, this gives Pondicherry, 5/i. 19m, 2O66s. East of Greenwich;
which is only 0*03 second less than was found by Messrs. Fleuriais and
myself in 1870.
6. Colombo and Jaffna. — A valuable check upon these determinations
was afforded by a direct telegraphic comparison between Captain Tupman
at Jaffna and Captain Donnan at Colombo. . Their difference was 39*36
seconds, while that resulting from the independent determination of each
station with Madras was 40*04 seconds ; as close as could be reasonably
expected from solar altitude time determinations and three unknown
personal equations involved in the operations.
7. Singapore. — It has already been mentioned, on page 12, that the
result of the American Expedition in January 1882 shewed an excess of
0*54 second over that found by Prof. Oudemans and myself in 1871. The
agreement is however sufficiently satisfactory for all present requirements.
In scientific undertakings dependent upon an individual, perfect free-
dom from all restraint is most calculated to secure the best attainable
results ; but when co-operation is necessary a programme is indispensable,
and can neither be too definitely laid down and studied beforehand, nor
too rigidly adhered to in its execution.
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