62 Transactions. 



we obtain for Svdnev 10 h. 4 m. 49-355 s. + 0-088 s. The Can- 

 adian value is 10 h. 4 m. 49-287 s. + 0-058 s. Difference, 0-068 s. 

 = 1-02" = 84 ft. for the latitude of Sydney— that is, the first 

 girdle of the world closed within 84 ft. 



New Zealand. 



The longitude of Wellington is discussed in the report of 

 8th August, 1884, of the Surveyor- General of New Zealand, 

 and in Appendix No. 1 of that report Mr. C. W. Adams fully 

 describes and tabulates the result of the determination for the 

 difference of longitude between Sydney (Australia), and Welling- 

 ton. The time-determinations of this series are of a high order, 

 and deserve every confidence. At the time (1883) the siphon 

 recorder had not been introduced on the cable, so that the clock- 

 beats were sent by hand and the deflections of the reflecting- 

 galvanoraeter were noted by eye. As Mr. Adams says in the 

 above appendix, " I received them at Wellington by reflecting- 

 galvanometer. but, instead of noting each signal by ' eye and 

 ear,' I simply tapped the key and recorded each signal on my 

 chronograph " — that is, as soon as the motion of the light-spot 

 had impressed itself on the brain, the key was tapped to record 

 the event. Although many trials were made for " the loss of 

 time in receiving signals," and the results are inconsistent 

 amongst themselves, yet the lack of self-recording cable-ap- 

 paratus is the weak point in the 1883 determination for difference 

 of longitude. The range for difference of longitude for the 

 1883 determinations is satisfactory, but of course may involve 

 constant errors without affecting the range. As we shall presently 

 see, the inter-agreement between the difference of longitude 

 between Sydney and Wellington obtained in 1883, and that in 

 1903, when the siphon recorder was used, is remarkably close. 



As Mr. T. King, observer at Wellington, has so fully given 

 the evolution of " the longitude of the Colonial Observatory, 

 Wellington," in the " Transactions of the New Zealand Institute," 

 vol. XXXV, 1902, pp. 436-47, it is not necessary here to cover 

 the same ground. 



As has already been explained, the determination of the longi- 

 tude of Southport (Australia) and Doubtless Bay (New Zealand) is 

 free from personal equation, and, so far as the Canadian work is 

 concerned, these two places are necessarily better determined 

 than places dependent upon them. In other words. Doubtless 

 Bay is better determined in longitude in the Canadian arcs than 

 is Wellington ; for WeUington to be as well determined as Doubt- 

 less Bay would mean perfect observations and perfect exchange 

 of time-signals between the two places, which is of course impos- 

 sible, no matter how good the work. 



