THE AIR-PUMP.
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.