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"The general scheme of Geisler's pump is shown here. A and B are pear-shaped glass vessels connected by a long narrow india-rubber tube, which must be sufficiently strong in the body (or strengthened by a linen coating) to stand an outward pressure of 1 to 1.5 atmospheres. A terminates below in a narrow vertical tube c, which is a few inched longer than the height of the barometer, and to the lower end of this tube the india-rubber tube is attached which connects A with B. To the upper end of A is soldered a glass two-way stop-cock, by turning which the vessel A can either be made to communicate through s and a hole in the hollow cock with the vessel to be exhausted." —The Encyclopedia Britannica, 1903

Air-Pump

"The general scheme of Geisler's pump is shown here. A and B are pear-shaped glass vessels connected…

"The general scheme of Geisler's pump is shown here. A and B are pear-shaped glass vessels connected by a long narrow india-rubber tube, which must be sufficiently strong in the body (or strengthened by a linen coating) to stand an outward pressure of 1 to 1.5 atmospheres. A terminates below in a narrow vertical tube c, which is a few inched longer than the height of the barometer, and to the lower end of this tube the india-rubber tube is attached which connects A with B. To the upper end of A is soldered a glass two-way stop-cock, by turning which the vessel A can either be made to communicate through s and a hole in the hollow cock with the vessel to be exhausted." —The Encyclopedia Britannica, 1903

Air-Pump

"The general scheme of Geisler's pump is shown here. A and B are pear-shaped glass vessels connected…

This barometer depends upon the changes in form of a think metallic vessel partially exhausted of air, as the atmospheric pressure varies.

Aneroid Barometer

This barometer depends upon the changes in form of a think metallic vessel partially exhausted of air,…

A collage of different types of atmospheres including auroras, snow, and rain.

Collage of Different Atmospheres

A collage of different types of atmospheres including auroras, snow, and rain.

"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.

"Measures atmospheric pressure. Pressure from the atmosphere compresses the mercury in the tray forcing the mercury accordingly into the graduated tube." —Quackenbos 1859

Barometer

"Measures atmospheric pressure. Pressure from the atmosphere compresses the mercury in the tray forcing…

"Danks rotary Puddling Furnace. The feel is burnt in an ordinary fireplace, a blast B being admitted under the bars and another over them A, level with the firing hole, so that by regulating the two streams of air the atmosphere can be kept reducing or oxidizing at will. A circular chamber or drum C is supported on massive friction rollers and arranged so that its axis is about level with the top of the bridge; at the other end is a movable terminal shaped like the frustum of a cone D, supported by chains or rods from a crane so that it can be swung on one side if required, thus serving as a door." — The Encyclopedia Britannica, 1893

Danks Furnace

"Danks rotary Puddling Furnace. The feel is burnt in an ordinary fireplace, a blast B being admitted…

A hand holding up a tube from a larger, mercury-filled tube.

Hand and barometer

A hand holding up a tube from a larger, mercury-filled tube.

"By means of the two hemispheres, it can be proved that the atmosphere presses upon a body equally in all directions. This device was invented by Otto Von Guericke, of Magdeburg, and is called the Magdeburg hemispheres." — Hallock, 1905

Magdeburg Hemispheres

"By means of the two hemispheres, it can be proved that the atmosphere presses upon a body equally in…

"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…

"A spectrum of sunlight is crossed by dark lines, many hundreds of whcih have been counted and accurately mapped. The more conspicious of these dark lines are distinguisged by letters of the alphabet. A few of these dark lines in the solar spectrum are due to absorption in the earth's atmosphere, but by far the greater number originate in the selective absorption of the solar atmosphere itself." — Avery, 1895

Visible spectrum

"A spectrum of sunlight is crossed by dark lines, many hundreds of whcih have been counted and accurately…