one were riding in the rear of a railway
train and watching the rails over which it has just passed. As we recede
from any point, the rails at that point seem to come nearer and nearer
together.

If we were passing through a forest, we should see the trunks of the
trees from which we were going apparently come nearer and nearer
together, while those on the sides of us would remain at their constant
distance, and those in front would grow further and further apart.

These phenomena, which occur in a case where we are sensible of our own
motion, serve to show how we may deduce a motion, otherwise unknown,
from the appearances which are presented by the stars in space.

In this way, acting upon suggestions which had been thrown out
previously to his own time by LAMBERT, MAYER, and BRADLEY, HERSCHEL
demonstrated that the sun, together with all its system, was moving
through space in an unknown and majestic orbit of its own. The centre
round which this motion is directed cannot yet be assigned. We can
only know the point in the heavens towards which our course is
directed--"the apex of solar motion."

By a study of the proper motions assigned by MASKELYNE to the brighter
stars, HERSCHEL was able to define the position of the solar apex with
an astonishing degree of accuracy. His calculations have been several
times repeated with the advantage of modern analytical methods, and of
the hundred-fold material now at our disposition, but nothing essential
has been added to his results of 1805, which were based upon such scanty
data; and his paper of 1782 contains the announcement of the discovery
itself.

His second paper on the _Direction_ and _Velocity_ of the solar system
(1805) is the best example that can possibly be given of his marvellous
skill in reaching the heart of a matter, and it may be the one in which
his philosophical powers appear in their highest exercise. For sustained
reflection and high philosophic thought it is to be ranked with the
researches of NEWTON in the _Principia_.

_Researches on the Construction of the Heavens._

HERSCHEL'S papers on the Construction of the Heavens, as he named it,
extended over his whole scientific life. By this he specially means the
method according to which the stars, the clusters, the nebulae, are
spread through the regions of space, the causes that have led to this
distribution, and the laws to which it is subjected.

No single astronomical fact is unimpo