INDEX. 



499 



Ireland, progress of the tidal wave 

 towards, 94. 



Iron, distilled, 305; rotation of its 

 particles, ib. ; magnetized by elec- 

 tricity, 314, 315 ; magnetic pro- 

 perties of, 332 ; rendered paramag- 

 netic, 336, 337 ; magnetic and 

 electric properties of, 347 ; elasticity 

 of, affected by magnetism, 352. 



Islands, character of their floras, 252. 



Isogeothermal lines of temperature 

 defined, 238, 239; parallel with 

 the isothermal lines, 246. 



Isomorphous crystals, 109. 



Isothermal lines of temperature de- 

 fined, 240 ; latitudes of, deviation 

 from the line of the equator, 245 ; 

 formula determining, 246 ; simi- 

 larity of vegetation in the same, 

 253. 



Italy, local attraction, occasioning in- 

 accuracy in measurement, 48. 



Ivory, M., his method of computing 

 heights, 120 ; his theoretical inves- 

 tigation of planet forms, 44; deduc- 

 tion from measurement of arcs of 

 the meridian, 48. 



JACOB, Mr., discovery of Saturn's 

 ring by, 66 ; periodic time of a 

 Centauri determined by, 399 ; pe- 

 riodic time of 70 Ophiuchi, 400. 



James, Colonel, measurements of, in 

 the General Survey of Great Britain, 

 47 ; density of the earth determined 

 by, 58. 



Jamin. M., remarks of. on substances 

 producing elliptical polarization, 193. 



January, epoch of its beginning the 

 year, 85. 



Jews, denominations of time in their 

 calendars, 85. 



Josephstadt, discovery of a comet 

 from, 367. 



Joule, Mr., heat considered a mecha- 

 nical force by, 275 ; his view of 

 elastic force, 276 ; amount of latent 

 force in a pound of coal, computed 

 by, 278 ; furnishing data to Pro- 

 fessor Thomson, 279 ; quantity of 

 heat generated in a unit of time by 

 electricity computed by,302 ; power- 



ful magnet obtained by electricity, 

 315; electric machines constructed 

 by, 328 ; experiments proving heat 

 and mechanical power convertible, 

 329. 



Jovial system, mass of the whole, 55. 



Julian Calendar, year of, the first of 

 our era, 86. 



June, 1833, reappearance of Saturn's 

 rings, 67 ; coincidence of times in, 

 84. 



Juno, the diameter of, 56 ; astrono- 

 mical tables of, 63. 



Jupiter, rotation of, distinguished from 

 the other planets, 7 ; periodical 

 inequality in his motions, 15; dis- 

 covery of telescopic planets between 

 Mars and, 20, 21 ; diameter of, 2 1 ; 

 his position with respect to the 

 equator of the solar system, 24 ; 

 inequalities in the motion of, appa- 

 rently anomalous, 25, 26 ; his 

 mass proved not homogeneous, 

 29 ; eclipses, 30, 31 ; compres- 

 sion of his spheroid computed, 

 39 ; eclipsed by Mars, 42 ; mass of, 

 compared with the sun, 55 ; his 

 diameter, 56 ; increase of density 

 in, 58 ; astronomical tables of, 60 ; 

 rapid rotation, 66 ; period of a year 

 in, ib. ; effect of his disturbing 

 energy, 81 ; photographic images 

 of, 226 ; light reflected by his at- 

 mosphere, 227 ; action of, on the 

 comet of 1770, 361, 362 ; on Hal- 

 ley's comet, 362, 363 ; comet re- 

 volving between the orbits of the 

 earth and, 367 ; future influence of, 

 on comets, 369 ; comet nearly ap- 

 proaching his fourth satellite, 370 ; 

 comets having their perihelia in hi* 

 orbit, 381. 



, orbit of, revolutions of its major 



axis, source of variation in.excen- 

 tricity, 17; slow revolution of its 

 nodes, decrease in its inclination to 

 the ecliptic, 19. 



with his satellites, an epitome 



of the solar system, 27 ; effect of 

 his excessive equatorial diameter 

 on their orbits, 28 ; satellites, libra- 

 tion in, 69 ; rotation of, 70. 



