INDEX. 



317 



Frost-work on windows, cause of, 185 

 Fruit, precautions to be used in packing, 



306 

 Fuel, elements of, 228 



perfect combustion of, bow attained, 



220 



Furnaces, hot air, how constructed, 219 

 Furs, why used for clothing, 147 

 Fumigation, 301 



Galvanism, how discovered, 289 



produced, 290 



simple experiment illustrat- 

 ing, 290 

 what is, 289 



Galvanl, discovers galvanic electricity, 290 

 Galvanic battery, ordinary effects of, 293 

 Gas, what is a, 8 

 Gases, law of diffusion of, 207 



not all invisible, 68 

 Glacier, what is a, 106 

 Glaciers, where occur, 106 

 Glass, burning, a double convex lens, 260 



ground for shades, use of, 233 

 Glasses, burning, 131 

 Gold, melting point of, 135 

 Gothic architecture, origin of, 45 

 Grain-weight, origin and construction of, 



20 



Grapes, ripe, why sweet, 303 

 Grass, grown in the dark, of a light color, 



272 



Gravitation, what is, 13 

 Gravity, centre of, 15 



illustrations of the laws and prin- 

 ciples of, 15, 16 



Oreasing carriage wheels, use of, 140 

 Greasy food, why relished in cold wea- 

 ther, 239 

 Green colors suited to fair complexions, 



2T3 

 Grindstones, In rapid motion why often 



burst, 23 

 Gun, essential properties of, 35 



how we take aim with a, 244 

 Gunpowder, composition of, 34 

 power of. 34 



when and how discovered, 

 35 



II 



Habitations, probable form of the 



human, 41 



Hail, what is, and how formed, 94 

 Hair, use of in mortar, 40. 

 Halls, for speaking, how constructed, 126 

 Hardness, what is~ 10 

 Headache, how produced by bad air, 209 

 Hearth-rugs, why feel warm, 145 

 stone, why feel cold, 145 

 Heat and cold, sensations of, 131 



animal, cause of, 236 



best conductors of, 144 



Heat, effects on the dissolving power ol 



liquids, 194 

 effects of, 131 

 effects of, on the bulk of some 



liquids, ITS 

 expands all bodies, 176 



illustrations of, 177 

 has no weight, 130 

 how communicated, 143 



illustrations of, 4 

 how diffused, 130 

 how evolved by combustion, 221 

 how measured, 187 

 good absorbers of, not gooo* reflect- 

 ors, 171 



greatest artificial, how produced, 293 

 greatest artificial, how measured, 



134 

 illustrations of radiation of, 161, 



162 



In ice, 130 

 latent, what is, 138 

 occasioned by chemical action, il- 

 lustrations of, 137 

 of the sun, 132 

 produced by friction, 140 

 radiant, 160 

 rays of, 171 

 reflection of, 171 

 solar, extends below the earth's sur 



face how far, 136 

 sources of, 132 



sun's differs from artificial, 133 

 velocity of transmission in different 



substances, illustrations of,- 144 

 vital, illustrations of, 141 

 what is, 129 



Health injured by reduction of the tempe- 

 rature of the body, 198 

 Height from which a body falls, how cal- 

 culated, 29 



Hiccough, what is, 123 

 Hides, how converted into leather by tan- 

 ning, 305 



Horizon, what is, 269 

 Horse-shoe magnets, 298 

 Horse-power, what is, 33 

 House, part most dangerous in a thunder 



storm, 282 



House, haunted, origin of stories concern- 

 ing, 128 



Hurricane, what is a, 80, 81 

 Hurricanes, where prevail, 80 

 Huts, first form of human habitations, 



41 



Hydrochloric acid, 304 

 first Hydrogen gas, its properties, 224 



the lightest of all bodies, 62 

 sulphuretted, 304 

 how formed, 304 

 what is, 224 

 Hydrostatics, definition of, 49 



Ice, " anchor," what is, 179 



