r nebulae, or into nebulous stars, and these
again, by the effects of the same cause, into insulated or double stars.
This chain of theorems, laid down in the memoir of 1811, is enforced in
1814 with examples which show how the nebulous appearance may grow into
the sidereal. HERSCHEL selects from the hundreds of instances in his
note-books, nebulae in every stage of progress, and traces the effect of
condensation and of clustering power through all its course, even to the
final breaking up of the Milky Way itself.

The memoirs of 1817 and 1818 add little to the general view of the
physical constitution of the heavens. They are attempts to gain a scale
of celestial measures by which we may judge of the distances of the
stars and clusters in which these changes are going on.

There is little to change in HERSCHEL'S statement of the general
construction of the heavens. It is the groundwork upon which we have
still to build. Every astronomical discovery and every physical fact
well observed is material for the elaboration of its details or for the
correction of some of its minor points. As a scientific conception it is
perhaps the grandest that has ever entered into the human mind. As a
study of the height to which the efforts of one man may go, it is almost
without a parallel. The philosopher who will add to it to-day, will have
his facts and his methods ready to his hands. HERSCHEL presents the
almost unique example of an eager observer marshaling the multitude of
single instances, which he himself has laboriously gathered, into a
compact and philosophic whole. In spite of minor errors and defects, his
ideas of the nature of the sidereal universe have prevailed, and are
to-day the unacknowledged basis of our every thought upon it. Some of
its most secret processes have been worked out by him, and the paths
which he pointed out are those along which our advances must be made.

In concluding this condensed account of HERSCHEL'S scientific labors,
it behoves us to remember that there was nothing due to accident in his
long life. He was born with the faculties which fitted him for the
gigantic labors which he undertook, and he had the firm basis of energy
and principle which kept him steadily to his work.

As a practical astronomer he remains without an equal. In profound
philosophy he has few superiors. By a kindly chance he can be claimed as
the citizen of no one country. In very truth his is one of the few names
which b