ate of 100 miles every second. Not that you must imagine that this
makes any obvious and apparent change in its position. No, for all
ordinary and practical purposes they are still fixed stars; thousands of
years will show us no obvious change; "Adam" saw precisely the same
constellations as we do: it is only by refined micrometric measurement
with high magnifying power that their flight can be detected.

But the sun is one of the stars--not by any means a specially large or
bright one; Sirius we now know to be twenty times as big as the sun. The
sun is one of the stars: then is it at rest? Herschel asked this
question and endeavoured to answer it. He succeeded in the most
astonishing manner. It is, perhaps, his most remarkable discovery, and
savours of intuition. This is how it happened. With imperfect optical
means and his own eyesight to guide him, he considered and pondered over
the proper motion of the stars as he had observed it, till he discovered
a kind of uniformity running through it all. Mixed up with
irregularities and individualities, he found that in a certain part of
the heavens the stars were on the whole opening out--separating slowly
from each other; on the opposite side of the heavens they were on the
average closing up--getting slightly nearer to each other; while in
directions at right angles to this they were fairly preserving their
customary distances asunder.

Now, what is the moral to be drawn from such uniformity of behaviour
among unconnected bodies? Surely that this part of their motion is only
apparent--that it is we who are moving. Travelling over a prairie
bounded by a belt of trees, we should see the trees in our line of
advance opening out, and those behind closing up; we should see in fact
the same kind of apparent motion as Herschel was able to detect among
the stars: the opening out being most marked near the constellation
Hercules. The conclusion is obvious: the sun, with all its planets, must
be steadily moving towards a point in the constellation Hercules. The
most accurate modern research has been hardly able to improve upon this
statement of Herschel's. Possibly the solar system may ultimately be
found to revolve round some other body, but what that is no one knows.
All one can tell is the present direction of the majestic motion: since
it was discovered it has continued unchanged, and will probably so
continue for thousands of years.

[Illustration: FIG. 87.--Old drawing of th