"Theory of the barometer. Fill a glass tube (over thirty inches long and closed at one end) with mercury. The column in the tube will fall until it is only about thirty inches long. The normal pressure of the air on the contents of the bowl balances the weight of the mercury in the tube." -Foster, 1921

Barometer Theory

"Theory of the barometer. Fill a glass tube (over thirty inches long and closed at one end) with mercury.…

"The bean with its roots in unboiled water will grow for a considerable time, as long as the mineral matter in the water will provide it with food materials. The roots of the plant in the boiled water will quickly die and the whole plant will then wither, because the roots no longer send the water up to the leaves." — Ritchie, 1918

Bean Plant in Jar

"The bean with its roots in unboiled water will grow for a considerable time, as long as the mineral…

"Apparatus used for calorimetric experiments." —The Encyclopedia Britannica 1910

Calorimetric Apparatus

"Apparatus used for calorimetric experiments." —The Encyclopedia Britannica 1910

"If the strong tube, or barrel, be smooth, and equal on the inside, and there be fitted to it the solid piston, or plug a, so as to work up and down, air tight, by the handle b, the air in the barrel may be compressed into a space a hundred times less than its usual bulk. Indeed, if the vessel be of sufficient strength, and the force employed sufficiently great, its bulk may be lessened a thousand times, or in any proportion, according to the force employed; and if kept in this state for years, it will regain its former bulk the instant the pressure is removed." —Comstock, 1850

Compression Experiment

"If the strong tube, or barrel, be smooth, and equal on the inside, and there be fitted to it the solid…

An egg dropped in fresh and salt water to show the properties of density.

Egg Plunged in Fresh and Salt Water

An egg dropped in fresh and salt water to show the properties of density.

"Faraday used in his experiments two identical pieces of apparatus, which were vertually two spherical Leyden jars. The outer coating EF was divided into two hemispheres, which could be fitted together airtight. The lower hemisphere F was fitted to a perforated stem, provided with a stop-cock G, so that it could be screwed to an airpump while the apparatus was being exhausted, and afterwards screwed into a foot H. The upper hemisphere was pierced by a tube, into which was cemented a shellac plug B. C is a metal wire passing down through B, which supports the hollow metal sphere D, forming the inside armature, and carries the metal ball A, by means of which D can be charged and discharged." — Encyclopedia Britannica, 1893

Faraday Experiment

"Faraday used in his experiments two identical pieces of apparatus, which were vertually two spherical…

"Explamation of Faraday's ice pail experiment." -Hawkins, 1917

Faraday's Ice Pail Experiment Explanation

"Explamation of Faraday's ice pail experiment." -Hawkins, 1917

"Galvani found that whenever the nerves of a frog's leg were touched by one metal and the muscles by another, convulsions took place on bringing the two different metals in contact." —Wells, 1857

Frog Experiment

"Galvani found that whenever the nerves of a frog's leg were touched by one metal and the muscles by…

"Joule's experiment on the mechanical equivalent of heat, in which he caused paddlewheels to rotate in a vessel of water by means of falling weights W." -Hawkins, 1917

Joule's Experiment

"Joule's experiment on the mechanical equivalent of heat, in which he caused paddlewheels to rotate…

"Experiment illustrating Lenz's Law. If a copper ring be held in front of an ordinary elecromagnet, and the current circulating through the coil of the magnet be in such a direction as to magnetize the core as indicated b the letters S N, then as the current increases in the coil more and more of the lines of force proceeeding from N pass through the ring OO from left to right." -Hawkins, 1917

Lenz's Law

"Experiment illustrating Lenz's Law. If a copper ring be held in front of an ordinary elecromagnet,…

A woman mixing milk with acid to test it, using a rotary motion with the bottle not pointed towards her face.

Mixing milk

A woman mixing milk with acid to test it, using a rotary motion with the bottle not pointed towards…

A woman putting milk into a test bottle. The pipette is held at an angle with the test bottle and its point against the inside of the neck.

Testing milk

A woman putting milk into a test bottle. The pipette is held at an angle with the test bottle and its…

A woman whirling samples of milk in order to seperate the fat so it can be measured.

Whirling milk

A woman whirling samples of milk in order to seperate the fat so it can be measured.

An apparatus, used to demonstrate how root-hairs are used to take in soil-water

Osmosis apparatus

An apparatus, used to demonstrate how root-hairs are used to take in soil-water

"The following simple experiment illustrates the effect of refraction:—Place a silver coin, m, at the bottom of the basin. The rays, i i, proceeding to the eye from the silver surface, render the coin visible. The point a, the eye, is then moved farther bck, so that the edge of the basin obstructs the direct rays, and of course the coin is no longer seen. If an attendant carefully pours water into the basin, so that the object is not moved, it will presently, as the water rises in the basin, become again visible. This arises from the refraction of the rays by the water, the image, indeed, appearing at n instead of at m." —Wells, 1857

Refraction

"The following simple experiment illustrates the effect of refraction:—Place a silver coin, m,…

A test tube

Test tube

A test tube