s from an incandescent gas, or from a
congeries of ignited solids, stars, or suns. If its spectrum be
discontinuous, it is a true nebula or gas; if continuous, a congeries of
stars.

In 1864, Mr. Huggins made this examination in the case of a nebula in
the constellation Draco. It proved to be gaseous.

Subsequent observations have shown that of sixty nebulae examined,
nineteen give discontinuous or gaseous spectra; the remainder continuous
ones.

It may, therefore, be admitted that physical evidence has at length been
obtained, demonstrating the existence of vast masses of matter in a
gaseous condition, and at a temperature of incandescence. The hypothesis
of Laplace has thus a firm basis.

[Sidenote: Opposition to the nebular hypothesis.] Notwithstanding the
great authority of the astronomers who introduced it, the nebular
hypothesis has encountered much adverse criticism; not so much, however,
from its obvious scientific defects, such as its inability to deal with
the cases of Uranus and Neptune, as from moral and extraneous
considerations. There is a line in Aristophanes which points out
precisely the difficulty:

Ho Zeus ouk on, all' ant' autou Dinos nuni basileuon.

A reluctance to acknowledge the presidency of law in the existing
constitution and movements of the solar system has been yielded only to
be succeeded by a reluctance to acknowledge the presidency of law in its
genesis. And yet whoever will reflect on the subject will be drawn to
the conclusion that the principle involved was really settled by Newton
in his "Principia"--that is to say, when it became geometrically certain
that Kepler's laws originate in a mathematical necessity.

As matters now stand, the nebular hypothesis may be regarded as the
first superficial, and therefore imperfect, glimpse of a series of the
grandest problems soon to present themselves for solution--the
mathematical distribution of matter and force in space, and the
variations of that distribution in time.

[Sidenote: The intellectual ruin of ecclesiasticism.] Such is the
history of the dispute respecting the position of the earth in the
universe. Not without reason, therefore, have I assigned the pontificate
of Nicolas V. as the true close of the intellectual dominion of the
Church. From that time the sceptre had passed into another hand. In all
directions Nature was investigated, in all directions new methods of
examination were yielding unexpected and beautiful