INDEX. 



480 



DOLLAND. 



Dolland, Mr., achromatic telescope 

 perfected by, 165. 



Donati, Signore, discovery of his 

 comet, 378 ; changes in, its irregu- 

 larities, 379. 



Doradus, nebulous patches on, 417. 



Dorpat, occultation of a star observed 

 from, 364. 



Double nebula:, 411. 



Double stars, catalogues of, 395, 396 ; 

 formulae obtaining the relative 

 position and motions, 396, 397; 

 eclipse in y Virginis, 397 ; orbit of, 

 determined, 398 ; eclipse in Her- 

 culis, Ib. ; orbits and periodic times 

 of, 398, 399 ; anomalies in motions, 

 400; optically double, 400, 401; 

 colours of, 401 ; rays composing 

 the light of, 401, 402 ; passage of 

 light from, furnishing data to as- 

 certaining their actual distance, 

 402, 403; data for finding their 

 masses, 403, 404; calculations 

 founded on the quantity of light 

 emitted from, 404; real and ap- 

 parent motions of, 404-406 ; appa- 

 rent periodic time, 406, 407; con- 

 nection of elliptical nebulas with, 

 411. 



Dove, Professor, law of the wind's 

 rotation developed by, 125; aver- 

 . age temperature of the earth's sur- 

 face estimated by, 237. 



Draco,, nebulous system in, 417. 



Draper, Professor, experiments of, on 

 fluorescence of light, 198; experi- 

 ments in photography, 213; pro- 

 perties of parathermic rays dis- 

 covered by, 219 ; spectrum produced 

 from diffracted light, 223 ; theory 

 of heat propagated by undulations, 

 267. 



Dunlop, Mr., revolution of a double 

 star calculated by, 400. 



Dusejour, M., distances of comets com- 

 puted by, 359. 



Dynamic electricity, 297. See Voltaic. 



theory of heat, fundamental 



principle of, 357. 

 Dynamic equator of the earth, 343. 



Dynamical theory of heat, 274, 275 ; 

 illustrated by liquefaction and con- 



EARTH. 



densation, 278 ; by generation of 

 steam, 277, 276 ; power of nature, 

 279-281. 



Dynamics, principle in, a law, with 

 regard to the earth's rotation, 72 ; 

 electro, discovery of ;iction of cur- 

 rents in, 316 ; the theory of, uni- 

 versal application of, 426, 427. 



EARTH, the, influence of its form on 

 attraction, 4; square of the moon's 

 distance from, 5 ; form of, 6, 7 ; 

 moon's influence on its rotations, 7 ; 

 diameter of, 21 ; mean distance 

 from the sun, ib. note ; permanence 

 of revolution in its times and sea- 

 sons, 23 ; perturbation in the mean 

 motioe of Venus and, 26 ; proof of 

 the motion of, in its orbit, of its 

 rotation, 32 ; variations in its at- 

 traction of the moon, 37 ; com- 

 pression of its spheroid, 38 ; in- 

 ternal structure of, 39 ; its mean 

 distance from the sun, 43 ; theo- 

 retical investigation of its figure, 

 44-46 ; dimensions of, determined, 

 48, 49 ; figure of, found by cal- 

 culating its variations in gravita- 

 tion, 49-51 ; density compared with 

 the sun, 56 ; experiments finding 

 its mean density, 57, 58 ; rate of 

 revolution round its axis, 58 ; its 

 diurnal rotation immutable, 71, 72 ; 

 changes in temperature and their 

 causes, 73, 74 ; nature of the revo- 

 lutio.ns producing geological changes, 

 76, 77 ; conjectures touching its 

 internal structure, 78 ; effects pro- 

 duced by solar and lunar attraction 

 affecting its equator, 79-81 ; its 

 form furnishing standards of weight 

 and measure, 89 ; rotation of, act- 

 ing on tides, 92 ; attraction of, 

 affecting the lunar atmosphere, 226 ; 

 conjectured constitution of its in- 

 terior, 231, 232 ; principles regu- 

 lating the diffusion of solar heat, 

 237-247 ; distribution of known 

 species of plants over, 249-252 ; 

 electric tension of, 291 ; lines of 

 magnetic force issuing from, 341 ; 

 magnetic properties of, 342, 343 ; 



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