130 PHILOSOPHICAL TRANSACTIONS. [aNNO 1737. 



ing all the observations which are actually making, new difficulties may arise, 

 and new objections be started, that may prevent its being entirely decided. 

 However, all this work cannot fail giving great light to this important question, 

 and procuring considerable advantages to geography, astronomy, and natural 

 philosophy. 



It is with this view, and particularly to render such important service to the 

 geography of Russia, that M. De Lisle thinks it necessary to undertake a work 

 of that nature in Russia ; towards executing which they have great advantages 

 which other nations have not. One of the principal of these advantages, is the 

 great extent of Russia every way. For were the meridian of the imperial ob- 

 servatory of Petersburg to be determined, it might be carried to between 22 

 and 13 degrees ; which is a fourth part of the distance from the pole to the 

 equator. The meridians of Mosco and Astracan are not of less extent ; and 

 consequently we might, by the measurement of some one of these meridians, de- 

 termine more exactly, than could have hitherto been done, the inequality that 

 subsists between the degrees of the meridian. 



This is what the great Cassini wished, when, after having, in the year 1701, 

 determined this inequality by the extent of 7 degrees observed in France, as has 

 been mentioned above, he says, that this fact might be verified by measurations 

 of greater extent, if the other princes of the earth would contribute as much 

 as the King of France, towards the perfecting of sciences. 



In the great extent which might be given to the meridian of Petersburg, 

 there would be the advantage of knowing, by operations connected together, or 

 uninterrupted, the magnitude of some degrees equal to those which have been 

 measured in France, and to that which the French astronomers have measured 

 in Sweden ; and not only all the degrees between the two, which the French 

 astronomers have not had in their power to observe, but also some degrees 

 farther northward than that measured by them in Sweden. 



As the exigencies of geography require the triangles, taken for the determi- 

 nation of the meridian, to be continued on every side, and principally in direc- 

 tions perpendicular to the meridian, or according to the parallels ; with how 

 great exactness may we not then determine the proportion of the degrees on the 

 parallels to those on the meridian, by means of the vast extent of the Russian 

 empire, which on its western side extending as far as all the dominions of 

 Europe from the most northern to the most southern, has no other bounds to 

 the east than the east itself, so to speak ; seeing its extent that way contains 

 near half the earth ? 



Another great advantage to be obtained by the work now proposed to be 

 made in Russia, is, that, coming after others, we shall reap the benefit of all 



