448 



INDEX. 



LigUtning, rarieties of, 393 



what is, 392 

 Line, vertical, 53 

 Liquefaction, what is, 237 

 Liquid at rest, condition of the surface of a, 

 133 

 pressure of a column of, 123 

 what is a, '23 

 Liquids, boiling point how changed, 242 

 flowing from a reservoir, 149 

 have no particular form, "23 

 heat conducting power of, 217 

 how cooled, 2-t 



move upon each other without fric- 

 tion, 1-4 

 pressure of, 125 



illustrated, 125 

 ■why some froth, 180 

 Bpecific gravity how found, 39 

 spheroidal state of, 240 

 to what extent expanded by heat, 



229 

 transmit pressure in all directions, 



125 

 when do they wet a surface, 30 

 Loadstone, what is a, 416, 417 

 Locks, canal, how operated, 137 

 Locomotive, efficacy depends on what, 29 

 Looking-glasses, how formed, 303 



M 



Machine, what is a, 90 

 Machines diminish force, 90 



do not produce power, 90 



how make additions to human 



power, 91 

 how produce economy of time, 94 

 motion in, takes place when, 92 

 simple, 93 

 Machinery, elements of, 93 



general advantage of, 92 

 magnetic, 433 



when caught on a center, 112 

 Magdeburg hemispheres, 177 

 Magnet, rotation of a, 431 



when traverses, 419 

 Magnets, artificial, 418 



horse-shoe, 420 

 native, 417 



power of artificial, 423 

 what are poles of, 418 

 Magnetic induction, 421 

 meridian, 425 

 phenomena, how accounted for, 



423 

 polarity, 419 



power of a body, where resides, 

 ,' 421 



'Magnetism, 417 



animal, what is, 413 

 electro, 429 



how excited by electricity, 432 

 how induced by the earth, 422 

 why not available for propel- 

 ling force, 433 

 Magneto-electric machines, 438 

 Magnifying glasses, 324 

 Mag^nitude, 12 



center of, 45 



Malleability, what is, 26 



examples of, 26 

 Man, how exerts his greatest strength, 88 



estimated strength of, 88 

 Mariotte's laws, what are, 166, 167 

 Matter, cause of changes in, 21 

 definition of, 11 

 essential properties of, 12 

 indestructible, 18 

 not infinitely divisible, 13 

 smallest quantity visible to the eye, 

 14 

 Materials, strength of, 115 



upon what depend, 

 115 

 Matting, how protects objects from frost, 



272 

 Mechanical powers, 93 

 Meniscus, 320 

 Meridian, magnetic, 425 



of the earth defined, 36 

 Metals, union of, how affects durability, 415 

 Meteors, how differ from shooting stars, 289 

 Meteorites, what are, 288 

 Meteoric bodies, supposed origin of, 289 



phenomena, 288 

 Meteorology, 266 

 Microscope, compound, 361 

 solar, 308 

 what is a, 360 

 Microscopes, varieties of, 361 

 Milk, why cream rises upon, 147 

 Mirage, 315 

 Mirror, plane, how reflects light, 303 



what is a, 302 

 Mirrors, burning, 303 

 concave, 308 

 convex, 311 

 parallel, effect of, 306 

 varieties of, 302 

 Mississippi, does it flow up hill, 152 



quantity of water in, 152 

 Mists and fogs, how occasioned, 273 

 Moisture in air, how determined, 269 

 Molecule defined, 14 

 Momentum, how calculated, 65 

 what is, 64 

 illustrations of, 64 

 Monsoons, theory of, 283 

 what are, 283 

 Moon, influence of on weather, 291 

 Motion, absolute and relative, 62 



accelerated and retarded, 03 

 apparent, affected by dietance, 359 

 circular, illustrations of, 78 

 compound, 72 



illustrations, 72 

 imparted to a body not instanlana* 



ously, 65 

 perpetual, in machinery, not possi> 



ble, 91 

 perpetual, in nature, 91 



example of, 91 

 reflected, what is, 71 

 * reversion of by belting, 101 



rotary. 111 

 rectilinear. 111 

 simple, illustrations of, 73 

 uniform and variable, 63 

 what IS, 62 

 whcu imperceptible to the eye, 3S0 



