XXVill Mr. Pickering’s Eulogy on 
genius, who should generalize these discoveries, and be enabled 
to extract from them the law of gravitation. This was what 
Newton accomplished, in his immortal work on the Mathematical 
Principles of Natural Philosophy.” * 
As soon as Newton had arrived at this great principle, (con- 
tinues La Place,) he perceived, that the important phenomena of 
the system of the world flowed from it. He found, among others, 
the following results; that the attractive force of a solid or a hollow 
sphere, upon a particle of matter placed without its surface, is the 
same as if the whole mass were collected in its centre; he proved 
that the rotation of the earth must flatten it at the poles; and he 
determined the laws of the variation in the degrees of the meridians 
and of gravity, upon the hypothesis, that the earth was homoge- 
neous; he perceived, that the action of the sun and moon upon 
the earth, as a spheroid, must produce an angular motion on its 
axis of rotation, must cause a retrogradation of the equinoxes, 
raise the waters of the ocean, and keep up, in that immense 
fluid mass, those oscillations, which we observe in it, called the 
ebb and flow of the tide. In fine, he satisfied himself, that the 
inequalities in the moon’s motion were owing to the united action 
of the sun and earth. “But, with the exception of what relates to 
the elliptical movements of the planets and comets, the attraction of 
spherical bodies, and the intensity of the attractive force of the 
sun, and of planets accompanied by satellites, all these discoveries 
were merely sketched out, or exhibited in their first draught. His 
theory of the planets is limited by the supposition that they are 
homogeneous; his solution of the precession of the equinoxes, not- 
withstanding its ingenuity and the apparent agreement of its results 
with observations, is yet defective in many respects. Among the 
* Exposition du Systéme du-Monde, p. 414. 
