60 Mechanical Philosophy, 



the rays of light; and furnishing new proof, both 

 of the materiality and amazing velocity of light, 

 and also of the reality of that motion which had 

 been ascribed to the earth. The same gentleman, 

 in 1737, discovered the nutation of the earth's 

 axis — that libratory motion, which is occasioned 

 by the inclination of the moon's orbit to the eclip- 

 tic, and the retrograde revolution of her nodes; 

 thus, in the course often years, making two of the 

 most important additions to astronomical know- 

 ledge that the century produced. 



While these noble and successful exertions were 

 making in Great-Britain, to improve the science 

 of astronomy, the philosophers of France were 

 employing themselves in the same field of inquiry, 

 and with very honourable success. The real figure 

 of the globe we inhabit had not been, before this 

 time, satisfactorily ascertained. M. Cassini, the 

 Astronomer Royal at Paris, believed its figure to 

 be that of a prolate spheroid, or, in other words, 

 that the polar diameter was greater than the equa- 

 torial; while Newton had been led, by his prin- 

 ciples, to a conclusion directly opposite, and had 

 taught that it must be an oblate spheroid, or flatted 

 at the poles. To determine the question, between 

 these contending powers, the French Royal Aca- 

 demy of Sciences, under the authority and patron- 

 age of Lewis XV. resolved to have two degrees 

 of the meridian measured, the one as near the 

 Equator, and the other as near the Pole, as pos- 

 sible. For this purpose, one company of philoso- 

 phers, consisting of Messrs. Godin, Condamine, 

 and BouGUER, to whom the King of Spain added 

 Don Ulloa and Don Juan, was dispatched, in 

 1735, to SouthAmerica; and another Company, 

 consisting of Messrs. Maupertuis, Clairault, 

 Camus, Le Monier, and Outhier, attended by 

 Professor Celsius, of Upsal, were sent to I^apland. 



