he Sandwich Islands; and in twenty-four, toward Washington
again, not because it has changed the plane of its vibration, but
because the earth has whirled beneath it, and the torsion of the
wire has not been sufficient to compel the plane of the original
direction to change with the turning of the earth. The law of
inertia keeps it moving in the same direction. The same experimental
proof of revolution is shown in a proportional degree at any point
between the pole and the equator.

But the watchers on the Acropolis do not get turned over so as to
see the moon at the same time every night. [Page 110] We turn down
our eastern horizon, but we do not find fair Luna at the same moment
we did the night before. We are obliged to roll on for some thirty
to fifty minutes longer before we find the moon. It must be going in
the same direction, and it takes us longer to get round to it than
if if it were always in the same spot; so we notice a star near the
moon one night--it is 13 deg. west of the moon the next night. The moon
is going around the earth from west to east, and if it goes 13 deg. in
one day, it will take a little more than twenty-seven days to go the
entire circle of 360 deg..

[Illustration: Fig. 42.--Showing the Sun's Movement among the Stars.]

[Page 111]
In our outlook we soon observe that we do not by our revolution
come to see the same stars rise at the same hour every night. Orion
and the Pleiades, our familiar friends in the winter heavens, are
gone from the summer sky. Have they fled, or are we turned from
them? This is easily understood from Fig. 42.

When the observer on the earth at A looks into the midnight sky
he sees the stars at E; but as the earth passes on to B, he sees
those stars at E three minutes sooner every night; and at midnight
the stars at F are over his head. Thus in a year, by going around
the sun, we have every star of the celestial dome in our midnight
sky. We see also how the sun appears among the successive
constellations. When we are at A, we see the sun among the stars
at G; but as we move toward B, the sun appears to move toward H.
If we had observed the sun rise on the 20th of August, 1876, we
should have seen it rise a little before Regulus, and a little
south of it, in such a relation as circle 1 is to the star in Fig.
43. By sunset the earth had moved enough to make the sun appear
to be at circle 2, and by the next morning at circle 3, at which
time Regulus would rise be