HISTORY OF GEODETIC OPERATIONS IN RUSSIA. 



309 



present time lougitiides of tive stations are kuovvu, aud the final results 

 will soon be published. 



In 1860, it was decided to carry an arc along- the fifty-second parallel, 

 which, when completed, would have, between Haversfordwest, in Eng- 

 land, and Orsk, on the river Ural, an amplitude of 63° 31'. To Russia's 

 share fell 29° 24', while the other countries had their work finished. In 

 addition to this, Russia at this time had only a few triangles suitably 

 situated that were sufiticiently accurate to form a part of this arc; 

 therefore it was necessary to revise some of the former work and to add 

 to it much that was wholly new. In the prosecution of this work 

 many obstacles were met with, especially while traversing the 

 marshes of Minsk, where, on account of th e heavy timber and the flat 

 character of the ground, it was necessary to build high signals, in 

 some cases as much as 150 feet in height. 



The field operations were completed in 1872. One can form an idea 

 of the magnitude of this triangulation when it is said that in Russia 

 there are 321 triangles, of which 199 are taken from Tenner's nets in 

 Poland and along the Volga, while 122 were measured by General 

 Zilinsky especially for this arc. They rest on seven base lines, two in 

 Tenner's chain aud five in the eastern part. Fifteen astronomical 

 stations have been occupied for longitude determinations, chiefly by 

 Russian officers, although six points were in other countries; these 

 were: Breslau, Leipzig, Bonn, Newport, Greenwich, and Haversford- 

 west. Time observations were made with portable transit instruments, 

 and latitudes were ascertained from observations made with the ver- 

 tical circles of Repsold. For the transmission of time, telegraphic 

 signals consisting of the turning aside of the needle of a galvanoscojie 

 were employed. Between two complete determinations of time four 

 groups of twelve signals each were sent at irregular intervals of time, 

 varying from 13 to 17 seconds. Six repetitions of such a set consti- 

 tuted a longitude determination. 



At the present time the computations are in press, forming parts of 

 volumes 46 and 47 of the Memoirs of the Topographic Section of the 

 General Staff. We are fortunately able to give the final results, as 

 follows : • 



Stations. 



Chenstobow — Warsaw 



Warsaw —Grodno 



Grodno — Bobruisk 



Bobruisk — Orel 



Orel — Lipetzk 



Lipetzk — Saratov 



Saratov — Samara 



Samara — Orenburg 



Orenburg — Orsk 



ChenstoboTV — Orsk 



Geodetic ditf. 

 of longitude. 



53 

 48 

 23 

 50 

 32 

 26 

 2 

 1 

 27 

 2u 



57.77 

 10.12 

 38.38 

 14.77 

 24.02 

 12.99 

 34.94 

 27.02 

 23.22 

 3.23 



Astronomic 



diflf. of 

 longitude. 



54 8. 85 



48 3. 45 



23 40. 50 



50 23.70 



32 18.15 



26 25.35 



2 21.60 



1 35. 85 



26 47.70 



25 51.15 



Diff. 



+11.08 



— 6.67 

 + 8.12 

 + 8.93 



— 5.87 

 +12. 36 

 —13. 34 

 + 8.83 

 —35. 52 

 —12. 08 



Arc of fifty- 

 I second paral- 

 lel in Tuetres. 



131,854.1 

 192, 501. 4 

 370, 468. 1 

 469, 605. 9 

 243, 027. 2 

 441, 906. 5 

 277, 561. 2 

 344, 917. 6 

 237, 290. 8 

 , 709, 132. 8 



