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"Crank M raises and lowers the two pistons C and D. The valves allow only for air to be removed from chamber J with a cutoff valve at K. The mercury filled barometer L measures the pressure in J." —Quackenbos 1859

Double Barrel Air Pump

"Crank M raises and lowers the two pistons C and D. The valves allow only for air to be removed from…

"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…

"The principal part of the aneroid barometer is a cylindrical air-tight box of metal closed by a corrugated top of thin elastic metal. The air is exhausted from the box, which is then sealed. Evidently, the pressure of the air on the outside of the cover will cause the cover to curve inwards, as the space inside of the cover is void of pressure, until the resistance due to the elasticity of the cover, aided by the resistance of a spring beneath it, is equal to the force exerted by the air." — Hallock, 1905

Aneroid Barometer

"The principal part of the aneroid barometer is a cylindrical air-tight box of metal closed by a corrugated…

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 homemade barometer made using a bottle.

Barometer

A homemade barometer made using a bottle.

The simplest form of the weather barometer made with mercury.

Barometer

The simplest form of the weather barometer made with mercury.

An instrument for determining the weight or pressure of the atmosphere, and hence the changes of the weather, or height of any ascent.

Barometer

An instrument for determining the weight or pressure of the atmosphere, and hence the changes of the…

"A Torricellian tube, firmly fixed to an upright support and properly graduated, constitutes a mercurial barometer. The zero of the scale is at the surface of the mercury in the cistern." — Avery, 1895

Barometer

"A Torricellian tube, firmly fixed to an upright support and properly graduated, constitutes a mercurial…

"The barometer is simply a pressure gauge that registers the pressure of the air. In this case the cup and tube at the bottom are protected by a brass or iron casing. At the top of the tube is a graduated scale. Attached to the casing is an accurate thermometer for determining the temperature of the outside air at the time the barometric observation is taken." — Hallock, 1905

Barometer

"The barometer is simply a pressure gauge that registers the pressure of the air. In this case the cup…

"A glass tube about 33 inches in length, open at one end, is completely filled with mercury, and being firmly closed by the thumb, is inverted and placed vertically in a cup containing mercury. When the thumb is removed, the mercury sinks in the tube till it stands, generally, about 30 inches above the level of the mercury in the cup, leaving in the upper part a space free of air, which receiveds the name of the Torricellian vacuum." — Chambers' Encyclopedia, 1875

Barometer

"A glass tube about 33 inches in length, open at one end, is completely filled with mercury, and being…

"A cistern barometer, being that generally seen in weather-glasses or ordinary barometers. The tube is bent at the bottom, and the cistern is merely an expansion of the lower end. Very generally, the cistern is hidden from view, and protected from injury by a wooden cover in front." — Chambers' Encyclopedia, 1875

Barometer

"A cistern barometer, being that generally seen in weather-glasses or ordinary barometers. The tube…

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.

"Suppose a to be a long tube, with the piston b so nicely fitted to its inside, as to work air tight. If the lower end of the tube be dipped into water, and the piston drawn up by pulling at the handle c, the water will follow the piston so closely, as to be in contact with its surface, and apparently to be drawn up by the piston, as though the whole was one solid body. If the tube be thirty-five feet long, the water will continue to follow the piston, until it comes to the height of about thirty-three feet, where it will stop, and if the piston be drawn up still farther, the water will not follow it, but will remain stationary, the space from this height between the piston and the water, being left a void space or vacuum." —Comstock, 1850

Barometer

"Suppose a to be a long tube, with the piston b so nicely fitted to its inside, as to work air tight.…

A barometer showing the amount of pressure at 760 millimeters of mercury (mm Hg), one standard atmosphere.

Barometer

A barometer showing the amount of pressure at 760 millimeters of mercury (mm Hg), one standard atmosphere.

"...being merely a tube of glass, nearly filled with mercury, with its lower end placed in a dish of the same fluid, and the upper end furnished with a scale, to measure the height of the mercury." -Comstock 1850

Barometer

"...being merely a tube of glass, nearly filled with mercury, with its lower end placed in a dish of…

"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…

"Barometer, an instrument for measuring the pressure of the atmosphere, based on an experiment performed in 1643 by Torricelli, a pupil of Galileo." -Foster, 1921

Barometer

"Barometer, an instrument for measuring the pressure of the atmosphere, based on an experiment performed…

The barometer is used to measure atmospheric pressure.

Barometer

The barometer is used to measure atmospheric pressure.

Blowing into a wide mouthed bottle with a cork and two glass tubes.

Barometer demonstration

Blowing into a wide mouthed bottle with a cork and two glass tubes.

"The aneroid barometer is an easily portable instrument, and avoids the use of any liquid. It consists of a circular metallic box, exhausted of air, the corrugated diaphragm of which is held in a state of tension by springs." — Avery, 1895

Aneroid barometer

"The aneroid barometer is an easily portable instrument, and avoids the use of any liquid. It consists…

"This is an instrument shaped something like a small clock, and the barometric pressure is read by means of a hand or indicator, on a scale of inches placed on the face like the minute divisions of a clock." — Waldo, 1896

Aneroid Barometer

"This is an instrument shaped something like a small clock, and the barometric pressure is read by means…

"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…

If the barometric tube is suspended from one of the scales of a balance, there will be required to balance it in the other scale a weight equal to the weight of the tube minus the upward pressure in the cistern.

Counterpoised Barometer

If the barometric tube is suspended from one of the scales of a balance, there will be required to balance…

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.

A device used for measuring pressure.

Piezometer

A device used for measuring pressure.

A barometer is a device used to measure the pressure of the atmosphere. A mercurial barometer, picture shown, uses mercury to show the atmospheric pressure, much like it did for a thermometer.

Pneumatics

A barometer is a device used to measure the pressure of the atmosphere. A mercurial barometer, picture…

An instrument for determining the tension of the aqueous vapor in the air or the relative humidity.

Psychometer

An instrument for determining the tension of the aqueous vapor in the air or the relative humidity.

"The whole length of the tube of the wheel barometer, from C to A, is 34 or 35 inches, and it is filled with mercury, as usual. The mercury rises in the short leg to the point a, where there is a small piece of glass floating on its surface, to which there is attached a silk string, passing over the pulley p. To the axis of the pulley is fixed an index, or hand, and behind this is a graduated circle, as seen in the figure. It is obvious, that a very slight variation in the height of the mercury at o, will be indicated by a considerable motion of the index, and thus changes in the weight of the atmosphere, hardly perceptible by the common barometer, will become quite apparent by this." —Comstock, 1850

Wheel Barometer

"The whole length of the tube of the wheel barometer, from C to A, is 34 or 35 inches, and it is filled…

"As the mercury rises and lowers in the barometer, the float F turns the index, I. Index I points to the correct reading on the graduated scale S." —Quackenbos 1859

Wheel Barometer

"As the mercury rises and lowers in the barometer, the float F turns the index, I. Index I points to…

The wheel barometer consists of a siphon barometer, the two branches of which have usually the same diameter.

Wheel Barometer

The wheel barometer consists of a siphon barometer, the two branches of which have usually the same…