three Degrees of the Meridian. 21 



results expressed in measures of which we do not know 

 the relation t() our own, in fact give us verv lilib assistance 

 m learning either the figure or dimensions of our olohe. 



It was not till ihe revival of science in Europe That the 

 two great philosophers Pluyghens and Newton first en- 

 gaged in the consideration of this question, :md reduced to 

 the known laws of mechanics the principles on which the 

 hgnre of the earth should be determined. 



They demonstrated that the rotatory motion should oc- 

 casion difierences in the force of gravity in difierent lati- 

 tudes, and consequently that parts o1' the earth in the neigh- 

 bourhood of the equator should be mere elevated than 

 those near the poles. 



• The most simple hypothesis, which first presented itself 

 to their imagination, was that which supposed the earth 

 to be throughout composed of the same kind of matter, 

 and its surface that of a spheroid generated by revoluriou 

 Jr)und Its axis. This hypothesis, adapted bv Newton only 

 as an approximation to the truth, is, in fact,' perfectly con- 

 sistent with the equilibrium to which particle^ in a state of 

 paste, or of tardy fluidity, would arrive in a short time 

 alter their present motion was impressed; and the eccen- 

 tricity derived from this hypothesis is at least not very 

 remote from that which aciually obtains in tht; present state 

 ot consistence and slability which trie earih has since ac- 

 quired. 



But the homogeneity of ihe matter of which the earth 

 consists, is at variance with all geological observations, 

 which prove evidently thai at leasi 5000 toises of the ex- 

 terior crust is formed of an immense mass of heterocreneous 

 matters varying in density from each other; and upon the 

 supposition of a state of fluidity of the whole, it should 

 follow that the straia should successively increase in den- 

 sity from the surface towards the centre, that the more 

 dense would accordingly be subjected to less ol' cenSrifiural 

 force, and consequenily'ihat the spheroidical form resuiting 

 from this cause would he less eccentric than would arise 

 ir(im a slate of perfect homogeneity. 



1 he most simple as well as the most efl'ectuai means of 

 verifying the hypoihesis respecting the figure of the earth, 

 IS to nieasure in the two hemispheres several arcs of its 

 meridians in different latitudes, at some distance from each 

 other. On this subject it must be allowed, thai the Aca- 

 demy of Sciences at Paris set the example, in giving the 

 original impulse to the undertaking, and not only com- 

 B 3 inenccd. 



