408 



PHYSICAL SCIENCES. 



HOROLOGIUM. 



Hoi-ologium, nebulous patches in, 417. 



Horton coal-mine, experiments with 

 the pendulum in, 57. 



Hours, cause of their mal-correspond- 

 ence over the globe, 86. 



Hudson's Bay, tide in, 98. 



Humboldt, his sufferings from rarity 

 of the atmosphere, 118; his expla- 

 nation of the apparent greater 

 acuteness of hearing observed at 

 night, 135 ; observations of, in 

 mines, 228 ; causes of disturbance 

 in the equal diffusion of heat enu- 

 merated by, 240 ; identical produc- 

 tions of the Old and New World 

 found by, 251 ; his distribution of 

 palms and grasses, 252 ; green 

 plants found growing in mines by, 

 253. 



Hunt, Mr., coloured image of the 

 solar spectrum obtained by, 209 ; 

 image obtained in England, 213 ; 

 his experiments in tracing images 

 by juxtaposition of bodies, 220, 

 221 ; experiments on the condensing 

 power of rays, 223. 



Hurricanes, origin and cause of, 125, 

 126 ; curve described by the axis of, 

 ih. ; their extent and velocity, 126, 

 127 ; phenomena resulting from 

 their revolving motion, 127; laws 

 of, making avoidance possible, 128. 



Huygens, theory originated by, 169. 



Hydrogen, proportion of, in water and 

 gases, 111; spectrum from, 303; 

 separated from water by electricity, 

 307. 



Hygrometer, dew-point measured by, 

 269. 



Hyperbolic motion, ratio of forces pro- 

 curing, 382. 



IAPETUS. seen by Mr. Lassell, 33. 



Ibn Junis, progress of science in his 

 time, 90. 



Ice, formation of, 271 ; force acting 

 in its formation, 276 ; stopping the 

 current of voltaic electricity, 309. 



Icebergs, drifting of, 100, 101 ; far- 

 thest range of northern andsouthern, 

 241 ; effect of electricity in colli- 

 sions, 284. 



IOTA. 



Iceland spar, its property of double 

 refraction, 181 ; polarized ray ana- 

 lyzed by, 187 ; transmission of ra- 

 diant heat by, 258 ; electricity 

 elicited from, 284. 



Illumination, comparative, of objects, 

 experiments determining, 227. 



Images, coloured, of the solar spec- 

 trum, 208-211 ; traced by contact 

 and juxtaposition of bodies, 219, 

 220; by electricity, 221 ; by media 

 absorbing hot rays, 222. 



India, arcs of the meridian measured 

 in, 48 ; discovery of Saturn's ring, 

 66 ; ancient monument of astro- 

 nomical knowledge, 85 ; observa- 

 tions confirming the antiquity of 

 astronomical science in, 88. 



Indian Ocean, the tidal wave in, 94 ; 

 monsoons blowing over, 124. 



Induction, law of, in electricity, 285, 

 286; magnetic, 314, 315; phe- 

 nomena of, produced by electric 

 currents, 324 ; illustrated by the 

 Atlantic telegraph, 325, 326; ve- 

 locity of electricity modified by 

 power of, 327 ; possibility of electro, 

 furnishing a motive power, 328 ; of 

 electricity by rotation of magnets, 

 330-332 ; as possessed by magnets, 

 336 ; paramagnetism evolved by, 

 337 ; means of accelerating, ib. ; 

 subject to the laws of mechanics, 

 338 ; analogy between electric and 

 magnetic, 341 ; of heavenly bodies, 

 affecting terrestrial magnetism, 346, 

 347 ; diamagnetic substances ca- 

 pable of, 348. 



Indus, comet passing through the con- 

 stellation of, 3797 



Inequality, the, of Jupiter and Saturn 

 marking historical epochs, 88. 



Insects, law of their dispersion, 255. 



Instruments, musical, 143, 149, 150 ; 

 imitating articulation of letters, 

 151, 152. 



Insulation in electricity, 285. 



Interference, laws of, neutralizing un- 

 dulations, 138, 139 ; the theory of, 

 referred to a general law, 169. 



Iota Ceta?, comet observed near, 372. 



Orionis, a nebulous star, 411. 



