315 



IHDEX, 



Earth, how proved to be in motion, 22 

 poles of, 296 

 temperature of, influence on the 



distribution of animals, 142 

 why made colder after sunset, 162 

 Earthquakes, probable cause of, 136 

 Ebullition, what is, 155 

 Ech6, distance necessary to produce, 125 

 what is, 124 



why sometimes double, 125 

 how produced, 124 

 where heard in greatest perfection, 



124 



Edge, straight, 243 

 Eel, electrical, 279 

 Elastic bodies, what are, 8 

 Electricity, 275 



and lightning, identity of, 285 



how proved, 285 1 Figure, 5 

 connection of light and heat, | Filtration, principles of, 7 



Exercise \vhy makes us xvarm, 238 

 Expansion by heat, 176 



Falling bodies, laws of, 25 



Fan, a, does not cool the air, 174 



Fanning the face, why cools, 173 



utility of, 174 

 Far-sightedness, cause of, 265 



how remedied, 265 



Fat people, why throw back their shoul- 

 ders, 17 



Feathers, why called light, 6 

 Feather, how attracts the earth, 14 

 Ferment, what is a, 305 

 Fermentation, how induced by yeast, 305 



278 



conductors of, 276 

 galvanic, greatest quantity, 



how excited, 292 

 galvanic of two kinds, posi- 

 tive and negative, 291 

 how called into action, 275 

 how excited by rubbing the 



fur of a cat, 278 

 invisible, 275 



natural agents active in pro- 

 ducing, "279 

 non-conductors of, 277" 

 of muscular action, 279 

 positive and negative, 278 

 produces heat, 136 

 velocity of, 278 



Electric cloud, discharge of, 2SO 

 Electrical machines, how constructed, 277 



repulsion, 276 



Electrified and non-electrified bodies, 276 

 Electro-magnetism, what is, 299 



when and how dis j 



covered, 299 

 metallurgy, 294 



principles of, 294 

 Electrotype process, 294 

 Entablature, 47 



Equinoxial storm, does it occur, 112 

 Esquimaux, why fond of oil and fat, 230 

 Ether, how removes grease, 307 



what is, 307 

 Evaporation, daily amount from the sea, 



110 



effects of, 197 

 phenomena of, 195 

 Eye, human, structure of, 262 

 muscles of, 262 

 parts of, 263 

 retina of, 263 



pained by sudden light, .266 

 pressure on, occasions the sensation 



of light, 26S 



Eyes, do not see alike with both, 263 

 Eyebrows, use of, 266 

 Eyelashes, use of, 266 

 Exertion, disagreeable in hot weather, 

 why, 240 



Fire, benefit of stirring a dull, 230 

 caused by friction, 139 

 heat of, cause of, 229 

 intensity depends on what, 230 

 reflection of, in our windows, 250 

 what is, 222 



why feels hot as we approach it, 161 

 whv placed near the floor of a room, 



160 

 in the niirht, why difficult to judge of 



the distance of, 269 

 places, open, advantages of, 219 



not economical, 218 

 Flame, candle, hottest part of, 232 

 color of, 231 



luminosity, depends on what, 222 

 of a lamp or candle, analysis of, 



232 

 of a candle, why points upwards, 



232 



solid particles in, 222 

 what is, 222 



when will it smoke, 223 

 Flames, why all not equally luminous, 231 

 Flues of stoves, why covered with black- 

 lead, 162 

 Flannel, how preserves ice from melting, 



143 

 Fluids, laws and phenomena of, 49 



two classes of, 49 

 Flying, how differs from leaping, 28 

 Force^ what is, 22 

 Food, hot, cooled by blowing, 159 



the fuel of the body, 238 

 Fogs, cause of, 84 



when and where occur, 90 

 why does not become dew, S9 

 Franklin's, Dr., theory of electricity, 277 

 Friction, what is, 22 



action of in exciting electricity, 



275 



Frieze, in architecture, 47 

 Frost, hoar, what is, 187 ^.^ 



rare under trees and shrul 



1S5 

 how a thin covering protects plants 



from, 167 

 readers the earth friable, 184 



