lternately in the grooves of the box, with their blacked sides
towards you, and look at them through a large and clear glass prism;
and if the light be strong, they will appear painted with the most
lively colours. If you cut on one of these papers the form of a
rainbow, about three-quarters of an inch wide, you will have a very
good representation of the natural one.

For greater convenience, the prism may be placed on a stand on the
table, made to turn round on an axis.

_The Artificial Rainbow._

Opposite a window into which the sun shines direct suspend a glass
globe, filled with clean water, by means of a string that runs over a
pulley, so that the sun's rays may fall on it. Then drawing the globe
gradually up, you will observe, when it comes to a certain height, and
by placing yourself in a proper situation, a purple colour in the
glass; and by drawing it up gradually higher, the other prismatic
colours, blue, green, yellow, and red, will successively appear; after
which, the colours will disappear, till the globe is raised to about
fifty degrees, when they will again appear, but in an inverted order,
the red appearing first, and the blue or violet last; on raising the
globe a little higher, they will totally vanish.

_The AEolipiles._

The aeolipile is a small hollow globe of brass, or other metal, in
which a slender neck or pipe is inserted. This ball, when made
red-hot, is cast into a vessel of water, which will rush into its
cavity, then almost void of air. The ball being then set on the fire,
the water, by the rarefaction of the internal air, will be forced out
in steam by fits, with great violence, and with strange noise.

If to the necks of two or more of these balls, there be fitted those
calls that are used by fowlers and hunters, and the balls placed on
the fire, the steam rushing from them will make such a horrible noise,
that it will astonish any person who is ignorant of the contrivance.

_The Talking Busts._

Procure two busts of plaster of Paris; place them on pedestals, on the
opposite sides of the room. Let a thin tube, of an inch diameter, pass
from the ear of one head through the pedestal, under the floor, and go
up to the mouth of the other; taking care that the end of the tube
that is next the ear of the one head, be considerably larger than that
end which comes to the mouth of the other.

Now, when a person speaks quite low into the ear of one bust, the
sound is reverberated