520 



INDEX. 



Pendulum, 37, 56. Note 100. 



, its variation discovered, 58. 



Penumbra, 45. Note 111. 

 Perigee, lunar, 40. Note 102. 



, variation of, 43. 



, variation of solar, 97- Note 147. 



Perihelion, 18. Note 57. 



, secular variation of, 19. Note 64. 



Periodic inequalities of the planets, 15. 



of Jupiter's satellites, 32. 



of the moon, 40. 



times, 6, 10. 



proportional to cubes of mean dis- 

 tances, 6 Note 26. 



Periodicity of the planetary perturba- 

 tions, 23. 

 Periods of rotation of the celestial 



bodies, 75 et seq. 

 Perkins, Mr., his experiments on the 



compressibility of matter, 88. 

 Peron and Le Sueur, MM., on the dis- 

 tribution of marine animals, 307. 

 Perturbations of the planets, periodic 

 and secular, 15, 25. 



expressed in sines and cosines of 



circular arcs, 23. Note 76. 



of Jupiter and Saturn, 29. 



of Venus and the earth, 30. 



of Jupiter's satellites, 32. 



of the moon, 40. 



of comets, 386. 



Phases of the moon, 45. 

 Phosphorescence, 325. 

 Phosphorescent action of solar spec- 

 trum, 326. 



Photographic rays of solar spectrum, 

 224 et seq. 

 pictures, 228. 

 Plane of ecliptic, 11. 



, its secular variation, 26. 



Planetary motions, 10, 15. 

 Planets move in conic sections, (i. 



, their forms, 5. * 



, atmospheres of, 273. 



, constitution of, 275. 



Plants, their distribution, 300 et seq. 

 Plateau, M., on complementary colours, 



185. 

 Platina, spontaneous combustion of, 



122. 



Poinsot, M.,on the invariable plane, 28. 

 Poisson, Baron, his researches on ca- 



pillary attraction, 128. On the dis- 

 tribution of the electric fluid, 315- 

 On the law of the magnetic force, 

 351. 



Polar star, 92. 



Polarization of light, 200. 



by refraction, 201. 



by reflection, 206. Note 205. 



, circular, 212 et seq. Note 209. 



, elliptical, 216. 



, discovery of, 219. 



of heat, 248. 



, circular, of heat, 250. 



Polarized light, 200. 



, undulations of, 204, 217- Note 



201. 



, phenomena of, 209 et seq. Notes 



207, 21 )H. 



in quartz, 212, 216. 



, interference of, 21 8. Note 211. 



Polarizing angles, 207. Note 205. 



apparatus, 209. Note 2()6. 



Poles of rotation, 5. Note 11. 



of celestial equator, or equinoctial, 



and of ecliptic, 11, 91. Note 46. 



of maximum cold, 297- 



Pouillet, M., his estimation of the quan- 

 tity of heat annually received from 

 the sun, 288. On the production of 

 atmospheric electricity, 320. 



Powell, Professor, on the dispersion of 

 light, 221. His experiments on heat, 

 246. 



Precession and nutation, 89. Notes 

 143, 144. 



, effects of, 90, 92. 



Principal axis of rotation, 85. 



Prism, its use, 178. 



Prismatic colours, 178. 



Probabilities, theory of, its utility, 68. 



Problem of the three bodies, 13. 



Projected, 6. Note 20. 



Q. 



Quadrant of the meridian, 101. Note 



151 



Quadratures, 11. Note 51. 

 Quadrupeds, their distribution, 308. 

 Quartz, or rock crystal, its properties, 



205, 212, 216. 



