Part 65

Statoliths, 303.

Steam-engine, 160, 265.

Steeple-jacks, 75.

Stereoscope, Wheatstone and Brewster's, 73.

Stevinus, on the inclined plane, 140; on hydrostatics, 141; on the equilibrium of systems, 142; discovers the principle of virtual velocities, 150; characterisation of his thought, 142; also 182, 187, 191.

Stone Age, 46, 321.

Störensen, 306.

Stove, primitive, 263.

Straight line, a, its symmetry, 98.

Straight, meaning of the word, 240.

Street, vista into a, 75.

Striae, in glass, 313.

Striate method, for detecting optical imperfections, 317.

Striking distance, 115, 127.

Strings, vibrations of, 249.

Struggle for existence among ideas, 217.

Substance, heat conceived as a, 177, 243 et seq.; electricity as a, 170; the source of our notion of, 199; rôle of the notion of, 203, 244 et seq.; energy conceived as a, 164, 185, 244 et seq.

Substitution-value of heat, 178, footnote.

Suetonius, 348.

Sulphur, specific inductive capacity of, 117.

Sun, human beings could not exist on, 3.

Swift, 84, 280.

Swimmer, Ampère's, 207.

Symmetry, definition of, 92; figures of, 92 et seq.; plane of, 94; vertical and horizontal, 94; in music, 99 et seq.

Sympathetic vibration, 22 et seq., 379.

Tailor, nature like a covetous, 9-10.

Tangent, the word, 263.

Taste, doubtful cultivation of, by the classics, 352-353; of the ancients, 353.