[Illustration: FIG. 1.]
The experiment represented in Fig. 1 illustrates the pressure of the
atmosphere. Fill a goblet with water up to the brim, and then cover it
with a sheet of paper which touches both the edge of the glass and the
surface of the water. Turn the glass upside down, and the sheet of
paper, held in its place by the pressure of the air, will prevent the
water from running out. It frequently happens that this experiment is
only successfully performed after a series of fruitless attempts on the
part of the operator. We therefore suggest that it shall be made over a
basin, and not where there are expensive articles to be ruined by a
douche of water.
[Illustration: FIG. 2.]
Fig. 2 represents another illustration of atmospheric pressure. Light a
piece of paper, and when it begins to burn brightly, thrust it into an
empty water bottle. Within a few seconds close the neck of the bottle
with a hard-boiled egg from which the shell has been removed. The
burning of the paper exhausts the air in the bottle, and the egg is
gradually thrust in by the pressure of the outside atmosphere. It will
finally pass completely through the neck of the bottle, giving a little
explosive sound.
[Illustration: FIG. 3.]
In Fig. 3 we have an experiment illustrating the laws of force. A dime
is placed on a table covered with a cloth or napkin. The coin can be
drawn from beneath the glass without touching it or slipping anything
under it. If the cloth near by be simply scratched with the nail of the
forefinger, the elasticity of the material communicates the motion to
the dime, which moves slowly in the direction of the finger, until it
finally comes out entirely from beneath the glass.
[Illustration: FIG. 4.]
The experiment shown in Fig. 4 is certain to result in the smashing of
several eggs; we therefore advise that they should be hard-boiled in
order to avoid serious catastrophes. By blowing into a claret glass
containing an egg, it is possible to cause it to jump out of the glass,
and with practice it may be made to pass from one glass into another.