regard to the extent to which the compression of air has been
actually carried, he tells us that 'Brockhaus says that air has as yet
been compressed only into _one-eighth of its original bulk_.' Is
it possible that a writer on Meteorology is unacquainted with the
well-known experiments of Dulong and Arago, and the more recent ones
of Regnault, in which the compression was three times the amount here
stated, or that he requires to be referred to those of Natterer, who, by
a powerful condensing apparatus, has lately compressed _seven hundred
and twenty-six volumes of air into a single volume_?"

[Any man who has succeeded in condensing seven hundred and twenty-six
volumes into one deserves the applause of the reading public. We
trust M. Natterer will extend his benevolent labors to all the great
libraries. With the most perfect apparatus of compression, however, we
doubt if contemporary literature will yield anything like so high an
average as 1 in 726.]

"8. In the paragraphs devoted to the optical relations of the
atmosphere, our author has shown a happy faculty for making his subject
obscure. After suggesting that the refraction of the rays in the
atmosphere may be due to what he calls its 'lenticular outline,' he
defines refraction to be 'the bending of a ray passing obliquely from a
rarer into a denser medium,'--a good enough popular definition, but for
its sad defectiveness. Is he not aware that the light is also bent in
penetrating obliquely from a denser into a rarer medium, as in passing
from the surface of a low plain to the eye of a spectator on a
neighboring mountain, and that the bending is just as great in this
direction of its motion as in the other? And does he not know that it
changes its course whenever it passes from a vacuum into any ponderable
medium or in the opposite direction? In future attempts to make
science easy, let him remember that these are all equally instances of
refraction, and should be included in its definition.

"Under the same head, we are led to infer that it is only in 'the warm
and moist nights of summer,' that 'the moon, as she rises above the
horizon, appears much larger than when at the zenith'; and we are
taught, in connection with the origin of the mirage and the spectre
of the Bracken, that 'rainbows are due to this condition of the
atmosphere.' If, instead of rainbows, we may be allowed to read _halos_,
we can understand the writer, who, instead of thinking of summer
s