DETERMINING OUR LONGITUDE.

Evening Star, Issue 6479, 21 December 1883, Page 2

DETERMINING OUR LONGITUDE.

The final observations in connection with the transit of Venus were concluded at tho Mount Cook Observatory at Wellington last night. Tho actual observations have been made by Mr C. W. Adams, first geodesical surveyor, Mr T. L. Banker assisting, and the telegraphic arrangements being conducted by Mr J. Cell. On tho other side, at the Sydney Observatory, tho observations were made by Mr H. O. Russell, the Government astronomer, Mr H. Lcnham being first assistant, and Mr J. S. Shapley, superintendent of the Cable Company, emperin-

tending the electrical arrangements, hjs 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 so fix the exact longitude of New Zealand. The method adopted for ascertaining the precise sidereal time was by simultaneous observations of the transit of a number of ftlndfiWenM " clock" stars,' And to prevent the chance of etibi had to be repeated on four nighw, the .signals being transmitted by telegraph direct from the' Sydney to’ the Mount Cook Observatory, all the IIcAW, mtag cbiineoted. On such a long circuit the i¥V)tr,lo current was necessarily weak, and consequently the signals hod to be received, not by the ordinary instruments, but by a Thompson reflecting galvanometer. As it was necessary for successful observation that the weather should be absolutely clear both at Sydney and here, and that the electrical conditions should bo favorable, it has occupied five weeks to obtain four satisfactory nights’ work. On each of these four nights 108 observations were made at each end, and the results duly recorded by the eleotrio current. The carelully-taken 482 signs will, it is believed, render error almost impossible; and, as Mr Adams recently visited both Melbourne and, Sydney for the purpose of a curtaining the amount of personal error existing between all the observers employed, it is believed that t he observations which were closed at Mount Cook last night will determine the longitude of Now Zealand, as compared with Greenwich, to within a chain. The results will bo forwarded to Ooloncl Tapman.