arth having turned meantime from West to East. This
objection has no weight, because the Earth controls not only all the
objects fixed to the soil, but also the atmosphere, and the clouds that
surround it like a light veil, and all that exists upon its surface. The
atmosphere, the clouds, the waters of the ocean, things and beings, all
are adherent to it and make one body with it, participating in its
movement, as sometimes happens to ourselves in the compartment of a
train, or the car of an aerostat. When, for instance, we drop an object
out of such a car, this object, animated with the acquired velocity,
does not fall to a point below the aerostat, but follows the balloon, as
though it were gliding along a thread. The author has made this
experiment more than once in aerial journeys.

Thus, the hypothesis of the Earth's motion has become a certainty. But
in addition to reasoning, direct proof is not wanting.

1. The spheroidal shape of the Earth, slightly flattened at the poles
and swollen at the equator, has been produced by the rotary motion, by
the centrifugal force that it engenders.

2. In virtue of this centrifugal force, which is at its maximum at the
equator, objects lose a little of their weight in proportion as they are
farther removed from the polar regions where centrifugal force is almost
_nil_.

3. In virtue of this same centrifugal force, the length of the pendulum
in seconds is shorter at the equator than in Paris, and the difference
is one of 3 millimeters.

4. A weight abandoned to itself and falling from a certain height,
should follow the vertical if the Earth were motionless. Experiment,
frequently repeated, shows a slight deviation to the East, of the
plumb-line that marks the vertical. We more especially observed this at
the Pantheon during the recent experiments.

5. The magnificent experiment of Foucault at the Pantheon, just renewed
under the auspices of the Astronomical Society of France, demonstrates
the rotary motion of the Earth to all beholders. A sufficiently heavy
ball (28 kilograms, about 60 pounds) is suspended from the dome of the
edifice by an excessively fine steel thread. When the pendulum is in
motion, a point attached to the bottom of the ball marks its passage
upon two little heaps of sand arranged some yards away from the center.
At each oscillation this point cuts the sand, and the furrow gets
gradually longer to the right hand of an observer placed at the center
of t