314 



HISTORY OF GEODETIC OPERATIONS IN RUSSIA. 



stations wliore the cotnputed attraction is eitlier insnfficient for the ex- 

 j>hination of the observed discrepancy or even contradicts it. Among 

 such stations the following are remarkable: 



Tiflis. 



The observed deflection , —7.56 



The computed deflection +.2.41 



Uifl'erence —9.97 



Shemalia. 



-23.21 

 + 16.43 

 -39.64 



As all of these stations lie approximately on the same parallel, and 

 each showed a strong deflection to tin south, there must lie to the south 

 under the surface of the earth an extent of matter of great density, or 

 to the north under the Caucasian ridge a mass of less density. The 

 latter hypothesis has found a parallel in the detlections observed near 

 the foot of the Himalaya Mountains. Besides the latitude deflections, 

 General Stebnizki calculated the deflections of the vertical at longitude 

 stations, but their number so far is insufficient to serve as a basis for 

 generalization. 



For more than a centur}^, the pendulum has been regarded in Russia 

 as a geodetic instrument of great value, but no very accurate observa- 

 tions were made prior to 1826-29, when Captain Lutke made a cruise 

 around the world on the man-of-war Seniavin. He swung a Kater 

 pendulum at ten stations. The results, published in 1833, gave for the 

 ellipticity 1 : 207.8, or 1 : 209 if two somewhat doubtful stations are 

 disregarded. Besides the desultory observations of Professor Parrot 

 of Dorpatin 1829, nothing of consequence was attempted until lS0.j-'08, 

 when the Academy of Sciences of St. Petersburg sent out an expeditiou 

 in charge of Sawitch, Smyslow, and Lenz. They selected twelve 

 stations along the great Russian meridional arc (Tornea, Nicolaistad, 

 St. Petersburg, Reval, Dorpat, Jakobstadt, Vilna, Belin, Kremenetz, 

 Kishener, Kanienet/ and Ismail), and employed a reversible Repsold 

 l)endulum. The results 1 : 309 for the ellipticity of the earth. 



Since this time, many observations have been made in various portions 

 of the Russian domain, and with the pendulum work, as with all other 

 branches of geodetic operations, the best methods soon find a place, and 

 results are obtained that are comparable with those of any country. 



