< 46 



ANALYTICAL INDEX. 



*"*w-s^**. 



verted into steam at various pressures, ii. 

 517; table showing the improvement of 

 Cornish engines, ii. 5'J3 ; table of observa- 

 tions on the height of storm-clouds by 31. 

 Arago, i. 537. 



Tacking a vessel, process of, ii. 215. 



Tails of comets, i. 521. 



Tr-ste, deceptions cf, ii. 95. 



Teeth of wheel?, ii. 259. 



Telescope, limited powers of, i. 51 ; unable 

 to magnify a star, i. 592 ; philosophy of 

 xhe telescope, ii. 346 ; ell'ect on lixed stars, 

 ii. 346. 



Telescope, astronomical, i. 480. 



Temperature of the sun's r.urface, i. 75. 



Temporary stars, ii. 360. 



Terrestrial attraction the combined action 

 of parallel forces, ii. 2'2'2. 



Terrestrial magnetism, Ampere's theory of, 

 ii. 124, 125. 



The earth, i. 477-498. 



Theorem regulating pressure and motion, ii. 



Theory of colors, i. 575-582. 



Thermometer, the, i. 329 ; ii. 131-146. 



Thermometer, mercurial, advantages of, ii. 

 132. 



Thermo-electricity, ii. 126. 



Thermo-electric piie, ii. 127. 



Thermo-electric scale of metals, ii. 127. 



Throttle- valve, ii. 462. 



Thunder, i. 547-549 ; distance at which it 

 may be heard, i. 553 ; cause of thunder, 

 i. f.54; popular impressions respecting the 

 effects of thunder, ii. 78. 



Thunder-bursts, i. 545. 



Thunder-clouds, common, i. 532. 



Thunder-storms, i. 531-558. 



Tid:il wave, the great, i. 217. 



Tides, the, i. 211-220; correspondence be- 

 tween the tides and the phases of the 

 moon, i. 211; the moon's influence on the 

 tides, i. 212, 213; the sun's influence, i. 

 214, 215; combined influence of the sun 

 and moon, i. 216; velocity of the tides, i. 

 218; range of the tides, i. 218, 219. 



Time of day, how found on land, i. 567,568; 

 at sea, i. 569. 



Tints, variety of, how produced by the sim- 

 ple component colors, i. 581. 



Toaldo, the meteorologist, i. 418. 



Toothed wheel, the, ii. 292, 293. 

 i Torricelli, a pupil of Galileo, discovers at- 

 mospheric pressure, i. 286. 

 ) Total eclipse of the sun, Halley's description 

 < of, i. 83. 



Transferring power of the Voltaic pile, i. 379. 

 | 1 .ansmission of sound, i. 553. 

 i Transparent and opaque bodies, i. 450. 

 Treadmill, the, ii. 255. 



Turning-lathe, the, ii. 248. 



Twilight at Venus and Mercury, i. 150. 



T-*':-way cock, ii. 482. 



U. 



Ultimate atom-, '. 6. 



Ultra-r.odiacal planets, i. 207. 

 Undulatory theory of light, i. 224, 232. 

 Uniform supply of light and heat from the 



sun, i. 53. 



Upward flashes of lightning, ii. 72. 

 Ursa Major or Great Bear, ii. 333. 

 Ursa Minor, ii. 334. 

 Useful arts, examples in, ii. 171, 172. 



Vacuity between our system and the stars, 



i. 586. 



Vacuum, maxim of the ancients that "Ma- 

 ture abhors a vacuum," i. 285, 286; a 

 perfect one cannot be produced, ii. W ; 

 vacuum produced by the condensation of 



steam, ii. 441. 



Valves of double-acting engines, ii. 448. 

 Valves, slides, and cocks, ii. 474. 

 Vapor, condensation of, ii. 313. 

 Vaporization, i. 331 ; ii. 299. 

 Vaporization and condensation, ii. 299. 

 Variable stars, how to observe them, ii. 350. 

 Variation of atmospheric pressure, i. 2i ! ti ; 



of the magnetic needle, ii. 113. 

 Variations, local, of the electricity of the 



air, ii. 155. 

 Velocity of the tides, i. 218. 

 Vent-peg, the, i. 300. 

 Venus, its diameter, position, &c., i. 145. 

 Vernier, the, for noting very small changes 



in the barometer, i. 294. 

 Vesta, i. 207. 



Visible stars, the, i. 585-596. 

 Vision, theory of illustrated by a rotating 



disk, i. 542; deceptions of vision, ii. 9o ; 



range of vision, ii. 357. 

 Vitreous electricity discovered by Dufaye, i. 



108. 



Vitrifications and fulgurites, ii. 67-69. 

 Volcanic lightning, i. 535. 

 Volcanic thunder-clouds, i. 535. 

 Volta's experiments in electricity, i. 138; 



his theory of contact, i. 364; of the origin 



of atmospheric electricity, ii. 151. 

 Voltaic pile, invention of, &c., i. 366 ; 



physical effects of the pile, i. 368; ento- 

 mological effects, i. 368; mode of action, 



i. 390. 

 Voltaire's investigations on the subject of 



comets, adopts Newton's conjectures, i. 



179. 



Volume and weight of thr mn, i. 70. 

 Voyages to the north pole 56. 



W. 



Wagon-boiler, the, for steam-engine, ii. 496. 



Walking engine, ii. 532. 



War-steamers, i. 280. 



Waste steam, resistance of t)ie, ii. 554. 



Water, decomposition of, i. 370; water raised 



by elastic force, ii. 53. 

 Water-spouts and whirlwinds, i. 599-608; ( 



spouts witnessed by Capt. Beechy, i. 60? J 



