308 HISTORY OF GEODETIC OPERATIONS IN RUSSIA.. 



tare the Baltic arc; to this was successively joined i^euuer's meridional 

 cbains in the provinces of Vilna, Lithonia, Volyiiia, and Podolsky. In 

 the years 1830-1844, triangles were added until the chain reached from 

 the isle of Jlohland (o Tornea, in the north, and in the following years 

 Tenner carried the southern end through Bessarabia, terminating at 

 Staraja-Nekrasovka, at the mouth of the Danube. For the continua- 

 tion of the arc northward from Tornea the co-operation of the Swedish 

 Government was necessary, as the best disposition of the triangles 

 threw the stations alternately in Kussia and in Sweden, finally cross- 

 ing the north of isorway. Struve went to Stockholm to lay the matter 

 before King Oscar, who at once entered into the spirit of the under- 

 taking, and not only gave his consent but contributed aid in carrying 

 it on. In 1845, this part of the work was begun, and with the assist- 

 ance of Selander, on the part of Sweden, and Hansteen, for Xorway, 

 the tield work was completed in 1852. 



This entire arc comprises 25° 20', in which there are 258 principal 

 triangles resting on ten base lines, and fixed in position on the earth's 

 surface by astronomic observations at thirteen stations. As a supple- 

 ment to this work may be mentioned the chronoraetrical expedition 

 between Pulkova and Dorpat, made in 1854, In this operation thirty- 

 one chronometers were transported ten times. The details of this arc 

 measurement are given quite fully in "Arc du M6ridien," which was 

 published in French and Russian in 1860. This arc has entered into 

 all of the more recent determinations of the figure of the earth, and in 

 the computations of General Bonsdorfi^" it alone gives for the ellipticity 

 V— 53, which agrees quite well with the best values. 



Arcs of parallel have also received some attention. In 1820, the 

 French Government announced that there was already in existence an 

 arc of i)arallel a])j>roximately in latitude 47° N. from Brest, on the west, 

 to Tchernowizt, on the east, and that if the Russians would continue 

 this arc eastward valuable geodetic data would result. The plan was 

 received with favor, but different obstacles intervened, so that it was 

 not until 1848 that it could be carried out. By this time the triangu- 

 lation had reached the so-called New Russia, and in the general pur- 

 pose to cover this entire section with a network of triangles General 

 Wrochenko, the chief, received instructions to so perform his work 

 that amongst his triangles there should be an uninterrupted chain 

 along this i)arallel of such strength and accuracy that they could form 

 an integral part of this arc. 



The field operations continued without serious interruption uj) to 

 their completion in 185G, extending over an arc of about 20° ampli- 

 tude from Bologan to Astrakhan, at the mouth of the Volga. For this 

 work three bases have been measured in addition to the checks which 

 came tlown from tlu* northern work. As the determination of the am- 

 ]>litude <lei)en(ls upon <iillerences of longitudes this part of the work 

 was delayed awaiting the construction of telegrai>h lines. At the 



