Analysis of a course of lectures : on mechanics, hydrostatics, pneumatics, and astronomy / read by James Ferguson.

  • James Ferguson
Date:
1761
Catalogue details

Licence: Public Domain Mark

Credit: Analysis of a course of lectures : on mechanics, hydrostatics, pneumatics, and astronomy / read by James Ferguson. Source: Wellcome Collection.

    18/44 page 18
    E. *8 3 chief ufc of this engine is to exhauft the air out of' glafs veffels, generally called receivers. If a fmall receiver, open at both ends, be placed, over the hole in the pump plate, and a perfon claps the palm of his hand on the top of the receiver, whilft another perfon exhaufts the air out of the receiver, his hand will be held down fp fall by the preffure of the atmofphere, that he cannot pull it off until the air be let into the receiver again. If a guinea and the down of a feather he hung within the top of a tall receiver, and let fall after the air is exhaufted out of it, they will both fall at the fame inftant on the pump plate whereon the receiver ftands. If a wet .bladder be tied over the top of an open receiver, then fet to dry, fo as to be tight like % drum ; and the receiver be then put upon the pump plate, and the air exhaufted out of it, the bladder will be broke by the weight of the atmo¬ fphere. If the neck of a hollow glafs bubble be immerfed in a phial of water, and covered with a clofe receiver* and then the air be exhaufted out of it; upon letting the air in again, its preffure on the water in the phial will force the water up into the bubble, fo as almoft to fill it. If a bell be covered with a clofe receiver, and the air be exhaufted out of it, the ftriking of the clapper againft the Tides of the bell will not be heard. If a pump be placed in water, under a receiver, and the air be exhaufted, no water can be raifed by working the pifton, until the air be let in again : which fhews, that the water rifes by the preffure of the air; and not by any fuch thing as fusion in flie pump. If a fmall receiver be placed on the pump plate, gt fo.tpe difla^cc from the hole, and covered with a
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