INDEX. 



T. 



Tangent, 10. Note 38. 



Tangential force, 17- 



Temperature, internal, of the earth, 81, 



277- 



, stratum of mean, 277- 



of mines, 277- 



of wells, 279. 



of ocean, 280. 



, superficial, of earth, 285. 



, effects of, on vegetation, 300. 



of space, 276. 



of the sun, moon, and planets, 273 



et seq. 

 Terrestrial latitude and longitude, 5. 



Note 11. 



meridian, 52. 



refraction, 173. 



magnetism, 341, 380. 



Tessular system, 125. 

 Tetrahedron, 125. Note 164. 

 Theory of Jupiter's satellites, 31. 



of the moon, 39. 



of the tides, 102. 



, atomic, 120. 



of sound, 143. 



of light, 171 et seq. 



of heat, 238. 



of electricity, 310 et seq. 



Thermal springs, 288. 

 Thermo-electricity, 374, 375. 

 Thermo-multiplier, 375. 

 Thunder, 153. 

 Tides, theory of, 102. 



, semi-diurnal, 103, 105. 



, semi-annual, 105. 



, effects of declination on, 107. 



Note 154. 



, neap and spring, 105, 109. 



, height of, 105, 108. 



, propagation of, 107- 



, courses of, 108. 



, forces producing, 109. 



at Batsha, 110. 



Time, mean and apparent solar, 94. 



, mean and apparent sidereal, 93. 



, equinoctial, 97. 



, equation of, 94. 



, square of, 42. Note 105. 



, divisions of, 94. 



Timocharis, his observations, 90. 



Torpedo, its electric properties, 340. 

 Tourmaline, its properties, 201, 203, 



206. Note 199. 

 Trade winds, 137- 

 Transit of Venus, 60. , Note 131. 

 Transmission of light, 197- 



of undulations, 144. 



of sound, 150. 



of heat, 240. 



Translation, 9. Note 36. 

 Triangulation, 53. Note 125. 

 Tropical revolution, 19. Note 69. 

 Tuning-fork, experiment with, 155. 



U. 



Undulations of water, 110. Note 156. 

 of air illustrated by those of a field 



of corn, 144. 

 of ether illustrated by those of a 



cord, 190, 215, 21?. 



, small, 13. 



Undulatory theory of light, 187 et seq. 



Universe, 28, 425. 



Uranus, 275. 



, disturbing action of Neptune on, 



25, 69 et seq. 



, his distance from the sun, 61, 69. 



, his satellites, 38. 



V. 



Valz, M., on Halley's comet, 392. On 



the nuclei of comets, 407- 

 Vapour, 262. 

 Variation, a lunar inequality, 40. Note 



104. 



of the compass, 341 et seq. 



Varieties of mankind, 308. 

 Vegetation, 300. 

 Velocity of light, 35. 



of electricity, 323. 



of comets, 399. 



of the gravitating force, 452. 



Venus, her action on the earth, 30. 



, her nodes, 16, 60. 



, transit of, 60. 



, climate of, 275. 



