310 HISTORY OF GEODETIC OPERATIONS IN RUSSIA. 



In 181G, was be^nii the j^vneral triangulatioti of Russia which was to 

 servo as the basis of accurate maps. At tirst the operations in difi'er- 

 ent sections were isohited, and when connections were made discrep- 

 ancies were discovered. This suggested to General Schubert, at the 

 time chief of trianguhition in the province of St. Peterburgh, that a 

 central department having charge of all astronomic, geodetic, topo- 

 graphic, and cartographic work should be established. His proposal 

 was favorably received by the authorities, and in 1822, the Military 

 Topograi)hic Cor[)S was founded with Scliubert at its head. At the 

 same time was organized the Topographic School, where young men 

 could i)repare themselves for service in the corps. That the founder 

 showed great wisdom in forming his phm of organization is apparent 

 froui the fact that but few changes have taken jilace up to the present 

 time. 



This institution is charged with all operations looking towards the 

 complete mappiug of all Kussian possessions. These in a great part lie 

 in inhospitable climes, and many are the abode of deadly fevers or sav- 

 age hordes, so that the work is of surpassing difficulty. All this, how- 

 ever, has tlelayed but not deterred the determined observers, so that at 

 the present time nearly all Russia is provided with a secondary trian- 

 gulation suitable for cartographic operations. In this work the only 

 imi)ortant feature introduced was in the measurement of baselines by 

 means of wires. This method, known in Europe as the JJiderin appa- 

 ratus, consists of a pair of tapes of diflferent metals, usually one brass 

 and one steel, each 25 metres long. In measuring both are used side 

 by side and are stretched under the action of a constant tension. Two 

 sliding scales attached to the top of a tripod are adjusted so that the 

 zero mark on one coincides with the end of the brass wire and the zero 

 of the other coincides with the end of the steel wire. Then the wires 

 are carried forward and the rear end of the brass wire is brought into 

 coincidence with the zero of the scale which had been adjusted to its 

 front end, and the same adjustment is made for the steel wire. If the 

 two wires should remain equal in length there would be no disagree- 

 ment in the zero marks, but as the rates of expansion of these two 

 metals are widely different the distance between the zeros at tlie tirst 

 laying of the wires is due to their unequal expansion, and each time 

 the wires are put in place this distance is augmented or diminished 

 according as the temperature is continually increasing or decreasing. 

 From this it can be seen that tlie entire base line can be regarded as 

 measured by a single length of an apparatus constructed on the Borda 

 principle and at a temjx'rature equal to the mean temperature exi)eri- 

 enced in measuring. With these wires great speed can be attained, 

 reaching as much as 8 kilometres a day, and judging from the Molos- 

 kowizy base, where the discrepancy between two measures was only 

 1 centimeter in a base 9,822 metres, sulhcient accuracy is readily secured, 



Not only for the purpose of deteruiiniug the amplitude of arcs of par- 



