long, makes out the universe as habitable
and cheerful as it is wide, and leaves us admiring its good more
than marvelling at its evil. He maintains that all solar and
planetary bodies have a central, vital heat, produced and maintained
by the same cause,--to wit, the gravitating or condensing force; its
intensity being as the mass. In the sun, the mass is so great, that,
in spite of its inferior density, more and intenser heat is
generated by condensation than in any or all of the planets. If the
whole orb is not incandescent, there is such intense heat in its
central portion as to generate gases, which, being thrown up through
its atmosphere, to a height at least as great as the whole diameter
of our globe, condense there again with an ineffably brilliant
combustion. The solid crust of the sun, he thinks, may be
comparatively cool,--as cool, perhaps, as our tropical climates,--by
the favor of cloud-curtains, which operate as screens, and reflect
off into space the heat of the combustion overhead. He might have
given more reasons than he has for this conclusion. Whether our
terrestrial aurora-borealis is caused by the combustion of gases that
have been generated by internal heat or not, we know that the
combustion of gas in the upper regions of our atmosphere would not
warm the surface of the earth much more than it would that of the
moon. It is easy enough to make out, from facts which our terrene
science has revealed to us, how the sun may be a perpetual fountain
of light, heat, and force to its most distant planets, without
having itself any superabundance of either of these emanations for
its own domestic consumption. The solar population may have no more
sunshine than we do, and may have even that mitigated with the
luxury of ice-creams, if not with that of arctic explorations and
polar bears. Whether they have as good opportunities as we for
astronomical observations is a little doubtful; but their
thermological studies must flourish abundantly, to say nothing of
their advantages in pyrotechnics.

_A Text-Book of Vegetable and Animal Physiology, designed for the
Use of Schools, Seminaries, and Colleges in the United States_. By
HENRY GOADBY, M.D., Professor of Vegetable and Animal Physiology
and Entomology in the State Agricultural College of Michigan, Fellow
of the Linnaean Society of London, etc., etc. Embellished with
upwards of four hundred and fifty Illustrations. New York: D.
Appleton and Company, 346