ovement
were one unable to see the objects close at hand displacing themselves.
For instance, if one is shut up in a railway carriage at night with the
blinds down, there is really nothing to show that one is moving, except
the jolting of the train. And even then it is hard to be sure in which
direction one is actually travelling.

The way we are situated upon the earth is therefore as follows. There
are no other bodies sufficiently near to be seen flying past us in turn;
our earth spins without a jolt; we and all things around us, including
the atmosphere itself, are borne along together with precisely the same
impetus, just as all the objects scattered about a railway carriage
share in the forward movement of the train. Such being the case, what
wonder that we are unconscious of the earth's rotation, of which we
should know nothing at all, were it not for that slow displacement of
the distant objects in the heavens, as we are borne past them in turn.

If the night sky be watched, it will be soon found that its apparent
turning movement seems to take place around a certain point, which
appears as if fixed. This point is known as the north pole of the
heavens; and a rather bright star, which is situated very close to this
hub of movement, is in consequence called the Pole Star. For the
dwellers in southern latitudes there is also a point in their sky which
appears to remain similarly fixed, and this is known as the south pole
of the heavens. Since, however, the heavens do not turn round at all,
but the earth does, it will easily be seen that these apparently
stationary regions in the sky are really the points towards which the
axis of the earth is directed. The positions on the earth's surface
itself, known as the North and South Poles, are merely the places where
the earth's axis, if there were actually such a thing, would be expected
to jut out. The north pole of the earth will thus be situated exactly
beneath the north pole of the heavens, and the south pole of the earth
exactly beneath the south pole of the heavens.

We have seen that the earth rotates upon its imaginary axis once in
about every twenty-four hours. This means that everything upon the
surface of the earth is carried round once during that time. The
measurement around the earth's equator is about 24,000 miles; and,
therefore, an object situated at the equator must be carried round
through a distance of about 24,000 miles in each twenty-four hours.
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