None
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  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. 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. 