he pendulum. The plane of the oscillations remains fixed, but the
Earth revolves beneath, from West to East. The fundamental principle of
this experiment is that the plane in which any pendulum is made to
oscillate remains invariable even when the point of suspension is
turned. This demonstration enables us in some measure to see the Earth
turning under our feet.

The annual displacements of the stars are again confirmatory of the
Earth's motion round the Sun. During the course of the year, the stars
that are least remote from our solar province appear to describe minute
ellipses, in perspective, in the Heavens. These small apparent
variations in the position of the nearest stars reproduce the annual
rotation of the Earth round the Sun, in perspective.

We could adduce further observations in favor of this double movement,
but the proofs just given are sufficiently convincing to leave no doubt
in the mind of the reader.

Nor are these two the only motions by which our globe is rocked in
space. To its diurnal rotation and its annual rotation we may add
another series of _ten more motions_: some very slow, fulfilling
themselves in thousands of years, others, more rapid, being constantly
renewed. It is, however, impossible in these restricted pages to enter
into the detail reserved for more complete works. We must not forget
that our present aim is to sum up the essentials of astronomical
knowledge as simply as possible, and to offer our readers only the "best
of the picking."

* * * * *

The two principal motions of which we have just spoken give us the
measure of time, the day of twenty-four hours, and the year of 365-1/4
days.

The Earth turning upon itself in twenty-four hours from West to East,
presents all its parts in succession to the Sun fixed in space.
Illuminated countries have the day, those opposite, in the shadow of the
Earth, are plunged into night. The countries carried by the Earth toward
the Sun have morning, those borne toward his shadow, evening. Those
which receive the rays of the day-star directly have noon; those which
are just opposite have midnight.

The rotation of our planet in this way gives us the measure of time; it
has been divided arbitrarily into twenty-four periods called hours; each
hour into sixty minutes; each minute into sixty seconds.

In consequence, each country turns in twenty-four hours round the axis
of the Earth. The difference in hours b