Lectures on Select Subjects in Mechanics, Hydrostatics, Hydraulics, Pneumatics, and Optics: With the Use of the Globes, the Art of Dialing, and the Calculation of the Mean Times of New and Full Moons and Eclipses

This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from ... Show synopsis This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1823 Excerpt: ...to feed flame; and so it also is for animal life. For a bird kept under a close receiver will soon die, although no air be pumped out; and it is found, that, in the diving-bell, a gallon of air is sufficient only for one minute for a man to breathe in. The moment when the candle goes out, the smoke will be seen to ascend at the top of the receiver, and there it will form a sort of cloud; but, upon exhausting the air, the smoke will fall down to the bottom of the receiver, and leave it as clear at the top as it was before it was set upon the pump. This shews, that smoke does not ascend on account of its being positively light, but because it is lighter than air; and its falling to the bottom when the air is taken away, shews that it is not destitute of weight. So most sorts of wood ascend or swim in water; and yet there are none who doubt of the wood's having gravity or weight. 30. Set a receiver, which is open at top, upon the air-pump, and cover it with a brass plate, and wet leather; and having exhausted it of air, let the air in again at top through an iron pipe, making it pass through a charcoal flame at the end of the pipe; and, when the receiver is full of that air, lift up the cover, and let down a mouse or bird into the receiver, and the burnt air will immediately kill it. If a candle be let down into that air, it will go out directly; but, by letting it down gently, it will purify the air so far as it goes; and so, by letting it down more and more, the flame will drive out the bad air, and good air will get in. 31. Set a bell upon a cushion on the pump-plate, and cover it with a receiver; then shake the pump to make the clapper strike against the bell, and the sound will be very well heard; but exhaust the receiver of air, and then if the clapper b... Hide synopsis