ClipArt ETC
"The pressure of the atmosphere may be easily shown by the tube and piston. suppose there is an orifice to be opened or closed by the valve b, as the piston a is moved up or down in its barrel. The valve being fastened by a hinge on the upper side, on pushing the piston down, it will open by the pressure of the air against it, and the air will make its escape. But when the piston is at the bottom of the barrel, on attempting to raise it again, towards the top, the valve is closed by the force of the external air acting upon it. If, therefore, the piston be drawn up in this state, it must be against the pressure of the atmosphere, the whole weight of which, to an extent equal to the diameter of the piston, must be lifted, while there will remain a vacuum or void space below it in the tube. if the piston be only three inches in diameter, it will require the full strength of a man to draw it to the top of the barrel, and when raised, if suddenly let go, it will be forced back again by the weight of the air, and will stright the bottom with great violence." —Comstock, 1850

Atmospheric Pressure

"The pressure of the atmosphere may be easily shown by the tube and piston. suppose there is an orifice…

An instrument used to measure atmospheric pressure.

Barometer

An instrument used to measure atmospheric pressure.

An instrument used to measure atmospheric pressure.

Barometer

An instrument used to measure atmospheric pressure.

"Mercury enclosed in a tube inverted and inserted into a bath of mercury can serve as a measurement of the atmospheric pressure, as the height of the mercury in the tube must directly correspond to the weight of the air pressing down on the bath of mercury underneath it." —Hallock 1905

Mercury Barometer

"Mercury enclosed in a tube inverted and inserted into a bath of mercury can serve as a measurement…

"The simple outline of the atmospheric engine. Its mode of operation is as follows. Steam is admitted from the boiler into the cylinder, through the tube l, by means of a regulating cock, e, which is worked by a handle outside the boiler; the pressure of the atmosphere above the piston being thus balanced by the force of the steam beneath it, the extremity of the lever beam to whch the piston is attached is elevated by proportionate weights, w, attached to the pump-rod, and the piston is drawn to the top of the cylinder, the other extremity of the beam being depressed." —Comstock, 1850

Newcomens Engine

"The simple outline of the atmospheric engine. Its mode of operation is as follows. Steam is admitted…

"A curious combination of the atmospheric pump and the forcing pump, invented by Mr. Trevethick." -Comstock 1850

Atmospheric and Forcing Pump

"A curious combination of the atmospheric pump and the forcing pump, invented by Mr. Trevethick." -Comstock…

"The action of the siphon illustrates the effect of atmospheric pressure. It is simply a bent tube having unequal branches, open at both ends, and is used to convey a liquid from a higher point to a lower, over an intermediate point higher than either." — Hallock, 1905

Siphon

"The action of the siphon illustrates the effect of atmospheric pressure. It is simply a bent tube having…