52 PROCEEDINGS OF SECTION A. 



The lougitudiual distance between the two fundamental 

 meridians, Port Darwin and Soiithport, can be deduced from the Aus- 

 tralian Arcs. 



Port Darwin-Melbourne, determined in 1883. 

 Melbourne-Sydnev, depending on various measurements from 



1864 to 1883. " 

 Sydney-Southport, by Klotz and Lenehan, in 1903. 

 The value of these arcs are — 



H. M. s. 

 Port Darwin-Melbourne . . . . 56 31 -65 (*) page 13 



Melbourne-Sydney .. .. 24 55-40 (*) page 13 



Sydney-Southport .. ..0 8 50-495 (f) page 188 



Port Darwin-Southport .. ■ .. 130 17*545 



If we now apply this difference to the Longitude of Southport 

 based on the Transpacific measurements, we obtain an independent 

 value for the Longitude of Port Darwin which, on being compared with 

 the previously assigned value, ■will exhibit the closing error of the 

 Eastward and "Westward chains. Thus — 



H. M. s. 



Difference of Longitude, Port Darwin-South- 

 port .. .. ' .. .. 1 30 17-545 



Longitude of Southport by the Transpacific 

 route . . . . . . .. 10 13 39 -782 E. 



Resulting Longitude of Port Darwin by the 



Transpacific and Australian arcs .. . . 8 43 22*237 E. 



Longitude of Port Darwin, via Potsdam, Persia, 



India, and Singapore . . . . . . 8 43 22 '316 E. 



Closing error . . . . ..000 *079 



Dr. Klotz brought this comparison to bear on the Longitude of 

 Sydney, and found the closing error 0*068s. = 84 feet. As the values 

 of the Australian arcs applied by him in the comparison have not been 

 modified since 1894, the closing error should be the same for Adelaide, 

 Melbourne, and Sydney, as that of Port -Darwin. The difference 

 of 0*011s. between his value and the one just computed is due to the 

 modified value of the Longitude of Potsdam by Prof. Albrecht, after 

 Dr. Klotz had concluded his own results ; as he himself points out in 

 (t), page 194. ■ 



* p. Baracchi. On the most probable Value and Error of Australian Longitudes, including 

 that of the Boundary Lines of South Australia with Victoria and New South Wales. 



t otto Klotz, LL.D. Transpacific Longitudes between Canada and Australia and New 

 Zealand. 1903-1904. 



