PROCEEDINGS OF SECTION A, 



49 



Since 1891 a new and to a great extent independent value of the 

 Longitude of Madras was obtained by Col. Burrard and Col. Lennox 

 Conyngbam by the telegraphic measurement of the four arcs Greenwich- 

 Potsdam, Potsdam-Teheran, Teheran-Bushire, Bushire-Karachi, which 

 they completed in 1896, the difference of longitude between Karachi 

 and Madras having been similarly well determined through Bombay 

 and Bolarum in the years 1875-77.* 



The results of these operations are as follow : — f 



In 1903 the interval Greenwich-Potsdam was again remeasured by 

 Prof. Albrecht and Prof. Wanach,{ and found to be O-098s. greater 

 than that given in the table^ above, and subsequently Prof. Albrecht, 

 in his adjustment of the longitudes of Central Europe§, gave as the 

 adjusted value for the Longitude of Potsdam — 

 Oh. 52m. 16 -062s. 



Accepting this last value as. the mosi, probable, we require to increase 

 the longitudes given by Col. Burrard in the above table, bv — 



0-109s. 

 Accordingly the Longitude of Madras becomes — 

 5h. 20m. 59 -246s. E. 



For the last two links of the eastward chain from Greenwich to 

 Australia, namely, Madras-Singapore and Singapore-Port Darwin, 

 we have only the single values determined in 1882 and 1883 respec- 

 tively.[| A check on the Longitude of Singapore is afforded by another 

 great chain of longitudes consisting of eighteen links, fourteen of which 

 join Greenwich to Vladivostock through Siberia, and the other four 

 extend from Vladivostock to Singapore through Shanghai, Hong Kong, 

 and Cape St. James. 



The portion from Greenwich to Vladivostock was measured by^ 

 General Sharnhorst and other officers of the Russian Army, and that 



• Account of the Opsrations of the Great Trigonometrical Survey of India. Vol. 9. 



t Account of the Opsrations of the Great Trigonometrical Survey of India. Vol. XVII. 



i Veroffentlichung des Konigl Preuszischeq .Giodatischen Institutes. Neue Folge N. 15 

 ftof. Dr. Albrecht. BJstimmung der Lingendifferenz Potsdam-Greenwich im Jahre, 1903. 



§ Astronomische Xachrichtsn N. 3993-94. Ausgleichung des Zentraleuropaischen Langen- 

 BetKS. von Prof. Th. Albrecht. 



I| 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. 



H Report of the Sapsrintendent of the U.S. Coast and Geodetic Survey. From Ist July, 

 1993, to 30th June, 1904; 



