Cohesion, 21, 33 Color, 435 bodies, 435 complementary, 436 primary, 440 prismatic, 433 theory of color vision, 440 three-color printing, 440 Commutator, 335, 336 Compass, 230, 240 Concave lens, 418 Condenser, 260, 474 Conductors, 246 Conservation of energy, 127 Continental code, 459 compared with the Morse, 452 Convection, 179 currents in nature, 181 draft of a chimney, 180 Convex lens, 416 Cooling, artificial, 210 Corpuscular theory, 442 Coulomb, 290 meter, 291 Couple, 101 Critical angle, 414 Crookes' tube, 456 Crystallization, 28 melting point of some crystalline substances, 203 Daniel cell, 276 Declination, 240 Density, 38, 52 methods for finding, 53 Dew, 192 Dew point, 193 Diffusion of gases, 13 Dipping needle, 240 Direct Current, 337 Dispersion, 433 Distillation, 208 Draft of a chimney, 180 Dry cell, 275 Dynamo, 330, 333 Dyne, 93 Eye, the, 423 action of, in vision, 423 defects of, 425 Ear, the, 386 trumpet, 361 Earth's magnetism, 238 Echoes, 362 Eclipses, 391 Efficiency, 142 engines (tests), 219 machines, 142 Elasticity, 31 Electric bell, 269, 287 charge, distribution of, upon a conductor, 253 circuit, 269 currents, 267 single phase, 479 three phase, 479 effects, 277 induced, 326 discharge in rarefied air, 452 motor, 339 screen, 256 Electrical capacity, 259 fields, 247 Electrification, 243 Electrolysis, 308 laws, 311 practical uses, 311 Electromagnet, 281 Electromagnetic theory of light, 456 Electromotive force, 267 unit of, 295 Electron theory, 252 Electrophorus, 263 Electroplating, 307 Electroscope, 244 Electrostatic induction, 248 Energy, 120 conservation, 127 falling water, 152 forms, 125 human body, 126 Energy, kinetic, 121 potential, 120 transference and transformation, 124 Engines, 213 Engines, gas, 222 steam, 213 turbine, 225 Equilibrant, 81 Equilibrium, 106 neutral, 107 stable, 106 stability, 108 unstable, 107 Erg, 119 Ether, 177 Evaporation, 18 cooling effect, 19, 197 rate, 198 Expansion, coefficient, 168 gases, 167 liquids, 168 peculiarity, in water, 168 solids, 169 water, on turning to steam, 206 Falling bodies, 109 experimental study, 111 laws, 113 Floating bodies, 48 Fluoroscope, 455 Foot candle, 396 Force, 79 dyne, 93 effectiveness, 134 graphic representation, 80 liquid, against any surface, 38 measuring, 79 moment, 99 parallel, 100 resolution, 96 units, 83 Forces, parallel, 100 Franklin's theory of electricity, 252 Fraunhofer lines, 439 Freezing, evaporation, 197, 199 mixtures, 210 Friction, 147, coefficient, 149 fluid, 150 kinds, 147 Friction, laws, 150 reducing, 148 uses, 149 Galvanometers, 289 Galvanoscope, 269 Gas engine, 222 efficiency of, 224 Gas meter, 75 Geissler tubes, 453 Gravitation, 103 law, 104 Gravity, 88, 104 acceleration due to, 111 cell, 277 center of, 105 Hail, 193