INDEX. 



511 



POLARIZATION. 



loured images formed by, 194; ac- 

 cidental, 195; discovery of, ib. ; 

 degraded light incapable of, 198 ; 

 communicating electricity, 220 ; 

 plane of motion of vibrations in, 

 223. 



Polarization of heat, first attempts, 

 264 ; successful experiments, 265- 

 267. 



of electricity by induction, 



286. 



, experiment showing the action 



of magnetism on, 319 ; affected by 

 mechanical compression, 352. 

 Poldice mine, the, temperature of the 



water pumped from, 229. 

 Poles, the, cause of the flattening of a 

 spheroidal mass at, 6 ; diameter of 

 Jupiter at, 27 ; experiment deter- 

 mining the increase of gravitation 

 towards, 49, 50 ; the, drifting of 

 ice from, 100, 101 ; of maximum 

 cold, centres of the isothermal lines, 

 245, 246 ; nature of magnetic force 

 distinguished by, 332 ; tour terres- 

 trial, of maximum magnetic force, 

 two magnetic, 343. 

 Pollux, an optically double star, 401. 

 Port Bowen Harbour, transmission of 



sound across, when frozen, 136. 

 Positive electricity, defined, 282 ; 

 mode of exciting, 283. 



impressions in photography, 204. 



Pouillet, M., his estimate of the mean 

 temperature of space, 119; quantity 

 of solar heat received by the earth 

 computed by, 238 ; data furnished 

 by, to Professor Thomson, 279 ; 

 development of electricity investi- 

 gated by, 291. 

 Powell, Baden, substances producing 

 elliptical polarization enumerated 

 by, 193; dispersion of light ac- 

 counted for by the undulatory 

 theory, 200, 201 ; experiments in 

 transmission of radiant heat, 262 

 attempts to polarise heat, 264. 

 Power, Mr., undulations producing 

 fluorescent light computed by 

 197 ; law of solar rays acting 01 

 media, 198. 

 Praesepe, the, in Cancer, 415. 



QUININE. 



^recession, a, in the equinoxes of 

 planets, its cause, 66; mean, of the 

 equinoctial point s, defined and cal- 

 culated, 80 ; influence of, on the 

 pole of the equator, on longitudes, 

 81. 

 Pressure, electricity elicited by, 283. 



284 ; law of electrical, 288. 

 ?rincipato Citeriore, earthquake in, 



234. 



Prisms, solar spectrum formed by, 

 159 ; neutralizing effects of colour, 

 164; of brown tourmaline, light 

 polarized by, 180 ; resolution of 

 the pure white sunbeam by, 222; 

 substance of, determining the point 

 of maximum heat in the solar 

 spectrum, 263, 264 ; electrical light 

 analysed by, 288. 



Problem determining the motions of 

 translation of the celestial bodies, 

 11; of the three bodies, 58; the 

 hardest astronomical, 92. 

 Procyon, light of, 402. 

 Proportion, definite, the law of, in 



mixing substances, 111, 112. 

 Protoxides of metals, their crystals, 



109. 

 Prussia, Eastern, fulgorites from, 



293. 



Ptolemy, decrease in the inclination of 

 Jupiter's orbit since the age of, 

 19 ; discovery of the Evection by, 

 35 ; Indian lunar tables calculated 

 in his time, 88 ; horoscope ascribed 

 to the age of, 89 ; effects of refrac- 

 tion observed by, 155 ; colour of 

 Sirius in his time, 401. 



QUADRATURES, the equation of the 

 centre in, 9 ; lunar orbit augmented 

 in, 35 ; tides affected by the moon 

 in, 96. 



Quadrupeds, distribution of distinct 

 species of, 255. 



Quartz, crystallised, light polarized 

 circularly by, 189, 190 ; varieties 

 of polarization exhibited by, 193. 



Quebec, extremes of temperature found 

 in, 247. 



Quinine, sulphate of, producing fluor- 

 escence of light, 197. 



