338 LAPLACE. 
the principle of universal attraction ; on the other hand, 
certain irregularities observed in the returns of the moon 
to the meridian. 
An observing geometer who, from his infancy, had 
never quitted his chamber of study, and who had never 
viewed the heavens except through a narrow aperture 
directed north and south, in the vertical plane in which 
the principal astronomical instruments are made to move, 
—to whom nothing had ever been revealed respecting 
the bodies revolving above his head, except that they 
attract each other according to the Newtonian law of 
gravitation,—would, however, be enabled to ascertain 
that his narrow abode was situated upon the surface of 
a spheroidal body, the equatorial axis of which surpassed 
the polar axis by a three hundred and sixth part; he 
would have also found, in his isolated immovable posi- 
tion, his true distance from the sun. 
I have stated at the commencement of this Notice, 
that it is to D’Alembert we owe the first satisfactory 
mathematical explanation of the phenomenon of the 
precession of the equinoxes. But our illustrious coun- 
tryman, as well as Euler, whose solution appeared sub- 
sequently to that of D’Alembert, omitted all consideration 
of certain physical circumstances, which, however, did 
not seem to be of a nature to be neglected without ex- 
amination. Laplace has supplied this deficiency. He 
has shown that the sea, notwithstanding its fluidity, and 
that the atmosphere, notwithstanding its currents, exer- 
cise the same influence on the movements of the terrestrial 
axis as if they formed solid masses adhering to the ter- 
restrial spheroid. 
Do the extremities of the axis around which the earth 
performs an entire revolution once in every twenty-four 
