The time was, and that not very long ago, when the air-pump was only
obtainable by the philosophical professor or by persons of enlarged
means. But now, owing to our “cheap way of doing things,” a small
air-pump may be obtained for about $5, and we would strongly advise
our young friends to procure one, as it will be a source of endless
amusement to them; and, supposing that they take our advice, we suggest
the following experiments.
The air-pump consists of a bell glass, called the receiver, and a stand
upon which is a perforated plate. The hole in this plate is connected
with two pistons, the rods of which are moved by a wheel handle
backwards and forwards, and thus pumps the air out of the receiver.
When the air is thus taken out, a stop-cock is turned, and then the
experiments may be performed.
Under the receiver of an air-pump, when the air has been thoroughly
exhausted, light and heavy bodies fall with the same swiftness. Animals
quickly die for want of air, combustion ceases, a bell sounds faint,
and water and other fluids change to vapor.