446 



INDEX. 



Elements, simple, 11 



number of, 11 

 Elevations, how determined by the boiling 



point of water, 242 

 Embankments, why made stronger at the 



bottom than at the top, 132 

 Endosmose, what is, 146 

 Engine, fire, construction of, 183 



steam, -51--54 

 Engraving, how affected by electro-metal- 

 lurgy, 415 

 Entablature, divisions of, 121 



what is, 121 

 X^uilibrium indifferent, 43 



law of, in all machines, 92 

 stable, 43 

 unstable, 4S 

 what is, 46 

 Equinoctial storm, 291 

 Evaporation, 23.S 



circumstances influencing, 239 

 influence of temperature on, 

 240 

 Exosmose, what is, 146 

 Expansibility, what is, 16 



illustrations of, 16 

 Expansion by heat, 228 



how measured, 233 

 Eye, S4T 



how judges of size and distance, 354 

 how moved, 34S 

 ' optic axis of, 353 



Structure of in man, 343 



Facade of a building, 121 



Far-sightedness, cause of, 353 



Feather attracts the earth, 32 



Fibrous substances non-conductors of heat, 



219 

 Filtration defined, 19 

 Fire, what is, 209 



Fishes, structure of the body of, 154 

 Flame, what is, 209 

 Flexibility, what is, 26 

 Flics, how walk upon ceilings, 176 

 Floating bodies, laws of, 138 

 Fluid, electric, 403 

 Fluids, what are, 24 

 Fly-wheel, use of, 17 

 Focus, what is a, 322 

 Form of bodies dependent on heat, 228 

 Forcing-pump, construction of, 183 

 Force defined, 21 



accumulation of, 87 

 internal, 22 

 magnetic, 418 

 molecular, 22 

 real nature of, 21 

 Forces, great, of nature, 21 

 electro-motive, 401 

 Fountains, ornamental, principle of con- 

 struction of, 135 

 Friction, 112 



advantages of, 113 

 how diminished, 112 

 kinds of. 112 

 rolling, 112 

 sliding, 112 



Friction, heat produced by, 214 



Freezing mixtures, composition of, 245 



Frieze in architecture, 121 



Frost, origin of, 272 



Fuel, what is, 265 



Fulcrum defined, 93 



Furs, why used for clothing, 219 



Furnaces, hot-air, 264 



how constructed, 265 



G 



Galvanism, 398 



Galvanic action, how increased, 403 

 battery, 401 



heating effects of, 403 

 phvsiological effects o^ 

 411 

 Galvanometer, 430 

 Gamut, the, 196 

 Gas, how differs from a liquid, 29 



what is, 23 

 Gases, how expand by heat, 232 



specific gravity, how determined, 41 

 Gaseous bodies, properties of, 23 

 Gasometcjs, construction of, 179 

 Gears, in wheel work, 101 

 Glass, opera, 365 

 Glasses, sun, 209 

 Glottis, what is the, 203 

 Glue, why adhesive, 25 

 Grain weight, origin of, 34 



bearing plants, construction of the 

 stems of, lis 

 Gravitation, attraction of, how varies, 30 

 defined, 30 

 terrestrial, 32 

 Gravity, action of, on a falling body, 55 

 center of, 45 

 specific, 37 

 Green wood, unprofitable to bum, 206 

 Grindstones, how broken by centrifugal 



force, SO 

 Guage, barometer, 259 

 steam, 259 

 rain, 277 

 Gun, essential properties of, 76 

 Gunpowder, effective limit of the force o^ 

 77 

 force of 76 

 Gurgle of a bottle explained, ISO 



Hail, what is, 280 



storms, where most frequent, 231 



stones, formation of, 281 

 Halos, what are, 336 

 Hardness, what is, 26 

 Hearing, conditions for distinctness In, 200 



range of human, 203 

 Heat, 205 



how diffuses itself, 206 



how measured, 206 



distinguishing characteristic of, 206 



nature of, 207 



theory of, 207. 203 



and light, relations between, 208 



devoid of weight, 209 



