"The compressed air manometer consists of a strong graduated glass tube of uniform narrow bore, closed at the top and fixed hermetically into the neck of a wide iron cylinder. The tube contains dry air, and its lower end dips below the surface of mercury contained in the cylinder. Attached to the side of the cylinder is a tube A, with a stop-cock, to afford communication with the vessel the pressure in which is to be measured. When the manometer is attached to the vessel containing compressed gas the mercury rises in the glass tube till the pressure of the air confined in the tube plus the height of the mercury column above the level of the mercury in the cylinder is equal to the pressure on the surface of mercury in the cylinder." —The Encyclopedia Britannica, 1903

Compressed Air Manometer

"The compressed air manometer consists of a strong graduated glass tube of uniform narrow bore, closed…

"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…

"For many purposes compressed air is preferable to steam or other gas for use as a motive power. In such cases air compressors are used to compress air. These are made in many forms, but the most common one is to place a cylinder, called the air cylinder, in front of the crosshead of a steam engine, so that the piston of the air cylinder can be driven by attaching its piston rod to the crosshead in a manner similar to a steam pump." —Hallock 1905

Air Compressor

"For many purposes compressed air is preferable to steam or other gas for use as a motive power. In…

An extreme form of a compressed foot, typically seen in the deer and ox. It is useful for land transit.

Compressed Foot

An extreme form of a compressed foot, typically seen in the deer and ox. It is useful for land transit.