pectrum of an ignited solid is continuous--that is, has
neither dark nor bright lines. Fraunhofer had previously made known that
the spectrum of ignited gases is discontinuous. Here, then, is the means
of determining whether the light emitted by a given nebula comes 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. In such a nebular mass, cooling by
radiation is a necessary incident, and condensation and rotation the
inevitable results. There must be a separation of rings all lying in
one plane, a generation of planets and satellites all rotating alike,
a central sun and engirdling globes. From a chaotic mass, through the
operation of natural laws, an organized system has been produced. An
integration of matter into worlds has taken place through a decline of
heat.

If such be the cosmogony of the solar system, such the genesis of the
planetary worlds, we are constrained to extend our views of the dominion
of law, and to recognize its agency in the creation as well as in the
conservation of the innumerable orbs that throng the universe.

But, again, it may be asked: "Is there not something profoundly impious
in this? Are we not excluding Almighty God from the world he has made?"

We have often witnessed the formation of a cloud in a serene sky. A hazy
point, barely perceptible--a little wreath of mist--increases in volume,
and becomes darker and denser, until it obscures a large portion of the
heavens. It throws itself into fantastic shapes, it gathers a glory
from the sun, is borne onward by the wind, and, perhaps, as it gradually
came, so it gradually disappears, melting away in the untroubled air.

Now, we say that the little vesicles of which this cloud was composed
arose from the condensation of water-vapor preexisting in the
atmosphere, through reduction of temperature; w