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BY ORDER OF THE

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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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