26 PLATEAU ON THE FIGURE OF A LIQUID MASS 
and adding successively fresh portions of oil, which we unite 
with the first. 
The next thing is to place the disc. This being attached by 
its axis to the rod which passes through the metallic stopper 
(§ 8), we begin by oiling it as well as the axis, then introduce 
it slowly into the alcoholic liquid, and cause it to penetrate by 
its edge into the sphere of oil. As the disc has previously 
been oiled, the sphere envelopes it without difficulty, and, what 
is remarkable, gradually of itself assumes such a position that the 
axis of the disc traverses it diametrically. This effect is evi- 
dently owing to the attractive action of this axis, or rather of 
the coating of oil with which it has been moistened,—an action 
which tends to operate in a symmetrical manner all around it, 
and thus brings the entire sphere of oil into a position symme- 
trical with respect to this same axis. Now it will be seen that 
the centre of the sphere tending, on the one hand, to remain at 
the height of that of the disc, on account of the superposition of 
the alcoholic layers of unequal density, and, on the other hand, 
to place itself in the axis of the disc, on account of the symmetry 
of the attractive actions exerted by the latter upon the oil, the 
centre of the sphere and that of the disc will coincide, and will 
thus remain in a fixed position. Only the sphere will then be 
slightly elongated in the vertical direction by the attraction of 
the axis of the disc; but this elongation is very trifling if the 
sphere present, as we have supposed, a diameter of 6 centimetres. 
10. The sphere of oil being thus suitably placed, we slowly 
turn the handle. We then presently see the sphere flatten at its 
poles and swell out at its equator, and we thus realize on a small 
scale an effect which is admitted to have taken place in the 
planets. 
However, although the results may be of the same nature in 
the case of the great planetary masses and in that of our little 
masses of oil, I must not omit to remark here that there is an 
essential difference between the forces which are in play in the 
two cases. In the first, the force which tends to give to the 
great planetary mass a spherical figure, and against which the 
centrifugal force acts, is universal attraction ; in the second, the 
force which acts the same part with regard to the small mass of 
oil, is molecular attraction, which is subject to different laws. 
But as, on either hand, the aggregate of the actions reduces 
itself to a contest between centrifugal force and another force 
