Part 46

Forwards, prophesying, 253.

Foucault, 57, 70, 296.

Foucault and Toepler, method of, for detecting optical faults, 313 et seq., 320.

Foundation of scientific thought, primitive acts of knowledge, the, 190.

Fourier, on processes of heat, 249, 278.

Fox, a, 234.

Franklin's pane, 116.

Frary, 338, footnote.

Fraunhofer, 271.

Freezing-point, lowered by pressure, 162.

Fresnel, 271.

Fritsch, 321.

Frogs, larvæ of, not subject to vertigo, 298.

Froude, 333.

Frustra, misuse of the word, 345.

Future, science of the, 213.

Galileo, on the motion of pendulums, 21; his attempted measurement of the velocity of light, 50 et seq.; his exclusion of a perpetual motion, 143; on velocities acquired in free descent, 143-147; on the law of inertia, 146-147; on virtual velocities, 150; on work, 172; his laws of descent, 193; on falling bodies, 225; great results of his study of nature, 214 et seq.; his rude scientific implements, 215; selections from his works for use in instruction, 368; also 105, 182, 187, 237, 272, 274, 283.

Galle, observes the planet Neptune, 29.

Galvanic, electricity, 134; current, 132; dizziness, 291; vertigo, 298.

Galvanoscope, 135.

Galvanotropism, 291.

Garda, Lake, 239.

Gas, the word, 264; mass of, enclosed in a cylinder, 179.

Gases, tensions of, for scales of temperature, 174.

Gauss, on the foundations of dynamics, 154; his principle, 154; also, 108, 274.

Genius, 279, 280.

Geography, comparison in, 239.

Geometers, in our eyes, 72.