INDEX. 



481 



ASTRONOMERS. 



Astronomers, fruits of their labours, 

 3 ; question still to be resolved by, 

 24; terrestrial orbit differently mea- 

 sured by, 36. 



Astronomical distances, method of 

 measuring, 43 ; tables, method of 

 forming, 58-64. 



Astronomy, its rank in the physical 

 sciences, an important office of, 1 ; 

 studies necessary to the study of, 

 2 ; the key to divers problems in 

 physical science, 3 ; the two greatest 

 discoveries in, 23 ; the three de- 

 partments of, 58 ; standards for 

 measurement afforded by, 83 ; ap- 

 plication of, to chronology, 87-89 ; 

 furnishing standards of weights and 

 measures, 89, 90 ; atmospheric ef- 

 fects connecting the laws of molecu- 

 lar attraction with, 102; progress 

 lately made by, 419, 420. 



Atalanta, diameter of, 56. 



Atlantic Ocean, direction of tidal 

 waves in, 93 ; conditions modifying 

 tides, 94; depth of, 96; currents, 

 100; origin of hurricanes, 126; su- 

 perficial temperature of, 244 ; dis- 

 tinct vegetation of the polar basin, 

 252 ; beds of algte in, 253 ; meteors 

 falling in, 421. 



i telegraph, 325, 326 ; terrestrial 



magnetism disturbing, 346. 



Atmosphere of nebulous stars, 411, 

 412. 



of planets, 226, 227. 



of the sun, its constitution, 42 ; 



indications of an absorptive sur- 

 rounding the luminous, 213 ; the 

 true, 224. 



terrestrial, solar rays bent by, 



in lunar eclipses, 40 ; influence of, 

 in solar eclipses, 41 ; its analysis, 

 pressure on the surface of the globe, 

 117; form of, gradual decrease in 

 density of its strata, 117, 118 ; in- 

 fluence of temperature on its density, 

 119; mean pressure of, variable, 

 120 ; the medium conveying sound, 

 129 ; sympathetic vibrations trans- 

 mitted by, 147, 148 ; its action on 

 light, falsifying vision, 153; phe- 

 nomena produced by accidental 



ATTRACTION, 

 in its strata, 155-156 ; 

 effects of increased density in the 

 stratum in the horizon, 157, 158; 

 lunar heat absorbed by, 227 ; cause 

 of the cooler air in higher regions of, 

 240, 241 ; sun's heat modified by, 

 244 ; action of electricity in, 284 ; 

 transmission of electricity by induc- 

 tion, 286 ; periodical variations of 

 electricity in, 291 ; accidental de- 

 velopment* of electricity, 291, 292 ; 

 cause of variations in its magnetism, 

 344, 345 ; nebulous bodies made 

 visible by, 421-423. 



Atmospheric air, extreme elasticity of, 

 105. 



pressure, effect of, on electricity, 



288. 



Atomic constitution determining crys- 

 talline forms, 109. 



Atoms, qualities of, determining the 

 nature of substances, 110; dif- 

 ferences in weight of, 111. 



Attraction, modes of, in spheres, in the 

 celestial bodies, 4 ; determining the 

 forms of planets, 6 ; determining 

 the motions of planets, 7 ; solar, 

 compelling the elliptical revolutions 

 of planets, 8 ; mutual, of planets, 

 complicating their motions, 10 ; in- 

 terference of, disturbing the motions 

 of heavenly bodies, 1 1 ; disturbances 

 from the operation of reciprocal, 

 13 ; disturbances from inequality 

 of, 14 ; of satellites to primaries, 

 little disturbed, 26 ; disturbing force 

 of, in spheroids, 27 ; its effects on 

 Jupiter's satellites, 28; sun's, of 

 the moon, 34 ; principle modifying 

 the earth's, 37 ; local, affecting the 

 plumb-line, 48 ; comparative force 

 of the sun's, 57 ; of an external 

 body affecting a spheroid, 79 ; pro- 

 ducing tides, 91, 92 ; of particles 

 of matter, 103; capillary, 113; 

 producing annual atmospheric un- 

 dulations, 121 ; the lunar atmo- 

 sphere affected by, 226 ; expansive 

 force of heat overcoming, 271 ; of 

 electricities, 283 ; destruction of, 

 producing electricity, 284 ; laws of 

 electrical, 286-288 ; modes of, in 



