Hearing, 386 Heat, capacity for water, 201 conduction, 173 constants for transmission, 220 convection, 179 effects, 161 engines, 213, 222 equivalent of fuels, 219 fusion, 201 measurement, 200 methods of transmitting, 173 produced by electric current, 318 radiation, 176 sources, 159 units, 162 vaporization, 205 work, 212 Heating of buildings, 182 direct and indirect radiation, 186 hot air, 183 water, 186 plenum system, 187 steam, 186 vacuum steam, 187 vapor steam, 187 Hertzian waves, 262, 449 Hooke's law, 33 Horse power, 123 electric equivalent of, 123 Humidity, 194 Hydraulic press, 42 elevator, 44 ram, 72 Hygrometers, 194 Hygrometry, 191 conditions for saturation, 192 dew point, 193 fog, 193 formation, of dew, 192 humidity, 194 hygrometers, 194 importance, 191 Hypothesis, 3 Images, concave mirrors, 405 construction, 405 definition, 392 plain mirror, 401 small apertures, 391 Impedance, 472 Incandescent lamp, 320 Inclined plane, 143 Inductance, 471 Induction coil, 343 Inertia, 87 Insulators, 246 Intensity of sound, 363 Interference, light, 442 sound, 374 Joule, 120, 319 Laws, boiling, 208 Boyle's 63 Charles', 165 electric action, 243 falling bodies, 113 floating bodies, 48 gravitation, 104 Hooke's, 33 induced currents, 326 intensity of light, 394 Lenz's, 328 liquid pressure, 37 machines, 131 magnetic action, 229 motion, 87 Ohm's, 298 pendulum, 116 reflection, 399 refraction of light, 411 vibration of strings, 378 Lenses, achromatic, 434 effect on light, 417 equation, 421 formation of images, 418 forms, 416 Leclanché cell, 275 Lever, 132 Leyden jar, 261 oscillatory nature of the discharge, 448 Light, compared with sound, 388, 444 electromagnetic theory, 456 intensity, 394 interference, 442 polarization, 445 rectilinear propagation, 389 reflection, 396 total reflection, 413 Lightning, 254 Lines, of force, 233 agonic, 240 isogonic, 240 Liquids, pressure, 36 Local action, 273 Luminous and illuminated bodies, 388 Machines, 129 advantages, 129 cannot create energy, 130 efficiency, 142 law, 131 mechanical advantage, 134 the six simple, 132 uses, 129 Magnetic action, 229 fields, 233, 466 induction, 231, 236 permeability, 237 poles, 229 properties, 230 retentivity, 231 substances, 230 effect of electric current, 279 Magnetism, 228 Magnetism, theory, 232 Major and minor triads, 369 Magneto, 328 Magnetoscope, 230 Magnets, 228 poles, 229 Major scale, 366 Manometric flames, 382 Matter, 4 effect of heat, 5 molecular theory, 5 properties, 34 states of, 4 states of, defined, 5 Mechanical advantage, 134 Megaphone, 365 Melting points, 203 Mercury arc rectifier, 347 Metric system, 8 Microscope, 427 Mirage, 414 Mirrors, 400 concave, 405 convex, 407 parabolic, 409 plane, 401