LONGITUDE OF NEW ZEALAND.

Poverty Bay Standard, Volume I, Issue 30, 3 January 1884, Page 3

LONGITUDE OF NEW ZEALAND.

[Per Association Telegram' . Wellington, Dec. 20. The final observations in connection with the transit of Venus were concluded at the Mount Cook Observatory last night. When Col. Tupan, of the Venus Expedition, was here he was prevented by unfavorable weather and his short stay from personally conducting the observations necessary to determine the precise longitude of New Zealand. They were accordingly entrusted to the Surveyor-General, who undertook to procure the required data, and under Mr. McKerrow’s supervision the work has since been carried on, Dr. Lemon superintending the necessary electrical arrangements. The actual observations have been made by Mr. C. M. Adams, first Geodesical Surveyor; Mr. T. L. Barker, assistant; and the telegraphic arrangements being conducted by Mr. J. Gell, Ass. T.E. On the other side, at the Sydney Observatory, the observations were made by Mr. H.C. Russell, 8.A., F.R.A.S., the Government Astronomer; Mr. H. H. Lenaham (first Assistant) and Mr. J. S. Shapely (Superintendent of the Cable Company), superintended the electrical arrangements, his Company having granted the free use of the cable for the purpose of these important observations to determine the exact time at each end of the base-line, and fix the exact longitude of New Zealand. The method adopted for ascertaining the precise sidereal time was by the simultaneous observations of the transit of a number of fundamental “ clock ” stars, and to prevent the chance of error these observations had to be repeated on four nights, the signals being transmitted by telegraph direct from the Sydney to the Mount Cook Observatory, all the lines being connected. On such a long circuit the electric current was necessarily weak, and consequently the signals had to be received, not by the ordinary instruments, but by Thomson’s reflecting galvanometers. As it was necessary for successful observations that the weather should be absolutely clear both at Sydney and here, and that the electrical conditions should be favorable, it has occupied five weeks to obtain four satisfactory nights’ work. On each of these four cases 108 observations were made at each end, and the results duly recorded by the electric current. These carefully-taken 432 signals will, it is believed, render error almost impossible, and as Mr. C. W. Adams recently visited both Melbourne and Sydney for the purpose of ascertaining the amount of personal error existing between all the observers employed, it is believed that all the observations which were closed at Mount Cook last night will determine the longitude of New Zealand as compared with Greenwich, to within a chain. The results will be forwarded to Colonel Tupman, and are expected to prove highly valuable, both in regard to the transit of Venus observations, and in navigation generally.