Knight's American mechanical dictionary : a description of tools, instruments, machines, processes and engineering, history of inventions, general technological vocabulary ; and digest of mechanical appliances in science and the arts . in which theela-sticity of the air itself is made to overcome theresistance of the valve. The valve, being ke)it to itsseat by a spring and the pressure of the air in thewind-chest, rei^uires a certain expenditure of forceto withdraw it from its seat on the sound-board. PNEUMATIC PARADOX. 1754 PNEUMATIC RAILWAY. Fig 3849. The pneumatic lever admits air from the
Knight's American mechanical dictionary : a description of tools, instruments, machines, processes and engineering, history of inventions, general technological vocabulary ; and digest of mechanical appliances in science and the arts . in which theela-sticity of the air itself is made to overcome theresistance of the valve. The valve, being ke)it to itsseat by a spring and the pressure of the air in thewind-chest, rei^uires a certain expenditure of forceto withdraw it from its seat on the sound-board. PNEUMATIC PARADOX. 1754 PNEUMATIC RAILWAY. Fig 3849. The pneumatic lever admits air from the wind-chestto oven^ome the resistance to the action. In, Fig. 3849, ^ is in open and Bia closed position. The twochambers a a b b areconnected by an inter-mediate passage c c,opened or ;ed bymeans of the bellowsd d. Ea^-h key of theinstrument is connectedwith its appropriate le-ver e e, and on beingstruck depresses one endof this lever, lifting oneof the valves ////andadmitting air to the bel-lows (i f/, which carry aleverto whoso projecting, end is attached a rod/( /i. connected with oneof the valves of the wind-chest; this is by thismeans pushed from itsseat, allowing the aircompressed in the chestto flow to the proper. Pneumatic Lever, pipe On withdrawing the finger from the key, a reverse actionof the valves is produced, as shown in the upper figure, the airfrom the bellows escaping into the chamber b and making itsexit through the passage ? g to the out^r atmosphere, i i arethe rods connecting the keys with their appropriate consequence of the width of the device, about three inches,every fifth lever is placed in the same row, the whole formingfive tiers. Pneu-matic Para-dox. That peculiar exhi-bition of atmospliuric pressure which retains a valveon its seat under a pressure of gas, only allowing afilm of gas to It is supposed to be owing tothe thin tihn of escaping gas or vapor that passes outall round the disk, creating a partial vacuum, bywhich
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