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Tension is the force which a gas always exerts when confined to a limited space. In the example, a partially filled football is placed in a glass jar (a receiver) from which air has been exhausted. The football immediately expands. This experiment also works with a bladder. A branch of mechanics that deals with the properties of gases is called pneumatics.

Pneumatics

Tension is the force which a gas always exerts when confined to a limited space. In the example, a partially…

A detail of the Wheeler and Wilson Sewing Machine. "s, thread-leader; t, face-plate covering...; v, presser thumb-screw; w, thread-check; x, tension-nut by which tension is regulated; y, tension-pulley around which the thread is wound, and which is caused to turn less or more easily by the nut x; z, thread-guide and controller; z2, presser-foot." —Whitney, 1889

Detail of Wheeler and Wilson Sewing Machine

A detail of the Wheeler and Wilson Sewing Machine. "s, thread-leader; t, face-plate covering...; v,…

"An instrument which, when applied over an artery, traces on a piece of paper moved by clockwork a curve which indicates the changes of tension of the blood within... a, band by which the instrument is fastened on; b, spring which rests upon the artery; c, adjusting-screw (with graduated head) which regulates the pressure of the spring b according as the pulse is strong or weak; d, d, supports for paper upon which the tracing is made; e, e to engage the paper positively; g, small spring clockwork (incased) by which motion is imparted to the feed-roller e1; h, milled-headed winding key; i, stop-motion; j, tracer attached to the oscillating arm k, which is moved by the rod l that connects this arm with the spring b." —Whitney, 1889

Sphygmograph with All Parts Labeled

"An instrument which, when applied over an artery, traces on a piece of paper moved by clockwork a curve…

"Carefully place a fine sewing needle upon the surface of the water. With care, and perhaps repitition, the needle may be made to float...Closely examine the surface of the water. Notice that the needle rests in a little depression or bed, just as it would if the surface of the water was a thin skin or membrane." -Avery 1895

Surface Tension and Needle

"Carefully place a fine sewing needle upon the surface of the water. With care, and perhaps repitition,…

"Since the strength of the fibers in adhesion is very much less than in tension and compression, adhesion enters into nearly every test as an important factor. Thus, if a piece of wood consisting of several fibers is tested in tension, the fibers a and b would probably not break at all, but be merely pulled out, the failure, as far as they are concerned, being due to lack of adhesion and not to a lack of tensile strength. Every tension test presents numerous cases of this king, the broken fibers presenting no even fracture, but being splintered and drawn out especially if the wood is good."—Government Printing Office, 1897

Behavior of Fibers in Tension Test

"Since the strength of the fibers in adhesion is very much less than in tension and compression, adhesion…