HISTORY OF GEODETIC OPERATIONS IN RUSSIA. 



309 



present time iongitiulet; of the stations are known, and the final rosnlts 

 will soon be published. 



In 1860, it was decided to carry an arc along* the fifty-second i)arallel, 

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

 land, and Orsk, on the river Ural, an amplitude of 03° 31'. To Eussia'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 sufficiently accurate to form a part of this arc; 

 therefore it w^as 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 triaugulation when it is said that in Russia 

 there are 321 triangles, of w^hich 109 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 and 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 Re psold. For the transmission of time, telegraphic 

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

 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. fSix 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 Staft". We are fortunately able to give the final results, as 

 follows : 



Stations. 



Geodetic ditf. 

 of lou>;itude. 



Chenatohow— Warsaw , 



Warsaw— Grodno 



Grodno — Bobruisk , 



Bobruisk — Orel 



Orel — Lipetzk 



Lipetzk — Saratov 



Saratov— Samara 4 



Samara — Orenburg 



Orenburg — Orsk 



Chenatohow— Orsk 



5 1 



3 27 



39 2G 



57.77 

 10.12 

 38.38 

 14.77 

 24.02 

 12.99 

 34.94 

 27.02 

 23. 22 

 3.23 



Arc of fifty- 

 secoudparal- 

 leliniiittre.s 



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 

 2, 709, 132. 8 



