INDEX. 



503 



MAGNETS. 



ing, 322 ; machine constructed on 

 the principle of, 325 ; relation of 

 heat to, 329. 



Magnets, influence of, on electric light, 

 307 ; fish possessing the power of 

 making, 311 ; effect of an electric 

 stream on, 312-314; obtained by 

 electricity, 315; power of electro, 

 measured, 315 ; cylinders acting as, 

 316, 317; producing electrical 

 effects, 322, 323; evolving elec- 

 tricity by rotation, 330 ; classifica- 

 tion of substances in relation to, 

 332 ; polarity a property of, 336 ; 

 effect on themselves of imparting 

 paramagnetism, 337 ; experiment 

 showing the lines of force of, 338 ; 

 properties of, indestructible by sub- 

 division, 338, 339; the earth 

 reckoned among, 342 ; planets 

 reckoned among, 346 ; action of an 

 electro, on copper, 351. 



Maguire, Captain, his observations on 

 magnetic storms, 345, 346. 



Malo, St., rising of the tide at, 98. 



Malus, M., discovery of polarization 

 of light by, 195 ; attempts of, to 

 polarize heat, 264. 



Malta, observations on Saturn's rings 

 made at, 66. 



Manchester, thunderstorm near, in 

 1835, 292. 



Mankind, distinct tribes of, 255 ; 

 limited perceptions of, 267. 



Marcet, M., rate of increase in tem- 

 perature below the earth's surface 

 calculated by, 230. 



Marco Polo, atmospheric effects ob- 

 served by, in ascending mountains, 

 118. 



Marine plants, laws regulating their 

 distribution, 252, 253 ; animals, 

 specific localities of, 254. 



Mariner's compass. See Compass. 



Mars, used in illustrating the possible 

 effects of the radial distributing 

 force, 19 ; telescopic planets be- 

 tween Jupiter and, 20, 21 ; diame- 

 ter of, 21 ; mean distance from the 

 sun, ib. note ; eclipse of Jupiter by, 

 42 ; parallax found by observing 

 his oppositions, parallax of, 53 ; in- 



MED1UM. 



ternal structure, 58 ; astronomical 

 tables of, 63; climate of, 225; 

 approach of the comet of 1770 to, 

 362 ; comets having their peri- 

 helia in his orbit, 381. 



Marseilles, transit of a comet across 

 the sun observed from, 374. 



Masses, of the sun, of planets and 

 their satellites, computations find- 

 ing, 55, 56. 



Mathematics, use of, in the study of 

 astronomy, 2. 



Matter, theory of its constitution, 

 102 ; hypotheses as to forces unit- 

 ing its particles, 103, 104 ; coun- 

 terbalancing action of elasticity and 

 cohesion, 105 ; crystallization com- 

 mon to all forms of, 109 ; indestruc- 

 tibility of its particles, 110 ; com- 

 position of unorganised bodies, sub- 

 ject to permanent law, 110, 111 ; 

 agent composing or decomposing, 

 112; mode of ascertaining the 

 magnetism of, 335 ; increatable, 

 indestructible, 353 ; proportion of, 

 to spare, 424. 



Matteucci, M., effect of electricity on 

 polished silver observed by, 221 ; 

 experiment showing polarization by 

 electricity, 286 ; doubts of, on the 

 polarity of diamagnetism, 348 note ; 

 experiments on magnetic action in 

 crystals, 350 ; observation on the 

 action of compression, 352. 



Maury, Lieutenant, calms named by, 

 123. 



Measurement of astronomical dis- 

 tances, formula assisting, 43. 



Mechain,M.,Encke's comet seen by,365. 



Mechanical equivalent of heat, 275. 



engines, incapable of generating 



force, 279. 



Mediterranean, the, conditions of, 

 shutting out the tidal wave, 98 ; 

 hurricane in, divided into two 

 storms, 126 ; vegetation of, 252. 



Medium, ethereal, transmitting mag- 

 netism, 344 ; density of, 356 ; pro- 

 bable relations of, to gravity, ib. ; 

 experiment testing its magnetic pro- 

 perties, 356, 357; functions of, 

 357 ; pervading the visible crea- 



