strict accordance with its title--elementary; but it is accompanied with
a variety of explanations of familiar facts on philosophical principles,
which possess attractions of a most amusive character.

The present portion of Dr. Arnott's work comprehends the subjects of
_Light_ and _Heat_, which admit of more familiar illustration than any
other branches of Natural Philosophy. Of this advantage the author has
fully availed himself in a variety of familiar exemplars, which, to
speak seriously are brought home to our very firesides. A few of these
facts will form a recreative page or two for another MIRROR: in the
meantime we quote a few illustrative observations on the most
interesting exhibitions of the day:--

"Common paintings and prints may be considered as parts of a panoramic
representation, showing as much of that general field of view which
always surrounds a spectator, as can be seen by the eye turned in one
direction, and looking through a window or other opening. The pleasure
from contemplating these is much increased by using a lens. There is
such a lens fitted up in the shops, with the title of _optical pillar
machine_, or _diagonal mirror_, and the print to be viewed is laid upon
a table beyond the stand of the lens, and its reflection in a mirror
supported diagonally over it, is viewed through the lens. The illusion
is rendered more complete in such a case by having a box to receive the
painting on its bottom, and where the lens and mirror, fixed in a
smaller box above, are made to slide up and down in their place to allow
of readily adjusting the focal distance. This box used in a reverse way
becomes a perfect camera obscura. The common show-stalls seen in the
streets are boxes made somewhat on this principle, but without the
mirror; and although the drawings or prints in them are generally very
coarse, they are not uninteresting. To children whose eyes are not yet