Part 48

Hat, a high silk, 24.

Hats, ladies', development of, 64.

Head-wave of a projectile, 323 et seq.

Hearing and orientation, relation between, 304 et seq.

Heat, a material substance, 177; difference between the conceptions of electricity and, 168 et seq.; substantial conception of, 243 et seq.; Carnot on, 156, 160 et seq.; Fourier on the conduction of, 249; not necessarily a motion, 167, 170, 171; mechanical equivalent of, 164, 167; of liquefaction, 178; quantity of, 166; latent, 167, 178, 244; specific, 166, 244; the conceptions of, 160-171; machine, 160; a measure of electrical energy, 133 et seq.; mechanical theory of, 133; where does it come from? 200.

Heavy bodies, sinking of, 222.

Heights of ascent, 143-151.

Helm, 172.

Helmholtz, applies the principle of energy to electricity, 184; his telestereoscope, 84; his theory of Corti's fibres, 19 et seq.; on harmony, 35, 99; on the conservation of energy, 165, 247; his method of thought, 247; also 138, 305, 307, 375, 383.

Hensen, V., on the auditory function of the filaments of Crustacea, 29, 302.

Herbart, 386 et seq.

Herbartians, on motion, 158.

Herculaneum, art in, 80.

Heredity, in organic and inorganic matter, 216, footnote.

Hering, on development, 222; on vision, 210.

Hermann, E., on the economy of the industrial arts, 192.

Hermann, L., 291.

Herodotus, 26, 234, 347, 350.

Hertz, his waves, 242; his use of the phrase "prophesy," 253.

Herzen, 361, footnote.

Hindu mathematicians, their beautiful problems, 30.

Holtz's electric machine, 132.

Horse, 63.

Household, physics compared to a well-kept, 197.

Housekeeping in science and civil life, 198.

Hudson, the, 94.

Human beings, puzzle-locks, 27.

Human body, our knowledge of, 90.