ASTRONOMY. 1.^)5 



a.s composed of meteorites, or masses of meteoiitie va])or produced by 

 heat l)roii<;iit about by condensation of meteor-swarms due to jjravity, 

 so that the exisiiiij^- (bstiiietion between stars, comets, and nebulae rests 

 on no physical basis. All alike are meteoritic in origin, the dill'erences 

 between them depending upon differences in tem])erature, and upon the 

 closeness of the component meteorites to one another. Novw (new stars 

 that blaze forth suddenly) are exi)lained as produced by the <;lash of 

 meteor-streams, and most variable stars are regarded as uncomlensed 

 meteor-streams. Stars with spectra like that of Ali)lia Orionis (lligel) 

 are considered not as true suns, but as mere clouds of incandescent 

 stones; probably the first stage of meteoritic condensation. Stars with 

 spectra of the first and second type represent the condensed swarm in 

 its hottest stages, while spectra of Secchi's fourth type indicate an ad- 

 vanced state of cooling." 



The general conclusions arrived at by Mr. Lockyer may be thus 

 summarized: All self-luminous bodies in space are composed of me- 

 teorites variously aggregated, and at various stages of temperature 

 depending upon the frequency and violence of their nnitual collisions. 

 Comets, nebula', bright-line stars, stiirs showing banded spectra of the 

 third type, including most long-period variables, are to be regarded as 

 veritable meteor-swarms; they are made np, that is to say, of an in- 

 definite multitude of separate and (in a sense) independent solid bodies, 

 bathed in evolved gases, and glowing with the heat due to their ar- 

 rested motions. "The existing distinction," w^e are told, "between 

 stars, comets, and uebuhe rests on no physical basis." Stars, on the 

 other hand, of the Sirian and solar types (constituting the only true 

 "suns") are vaporized meteor-swarms; their high temperatures repre- 

 sent the surrendered velocities of myriads of jostling particles, drawn 

 together by the victorious power of gravity. 



"Collisions" are not however exclusively relied upon for the cos- 

 mical production of light and heat. It is admitted that the luminosity 

 of comets and nebuhc must be largely due to electrical excitement; 

 uor is any reason apparent why its inlluencc should be restricted to 

 these two classes of bodies. Destrnctidn of movement by impacts can 

 scarcely be made to snpply its jdace. Occasional illuminative effects 

 may be derived from it, but none that are uniform and i)ermanent. 



The small bodies which, more or less plentifully distributed, api)ear 

 to ])ervade space, are in this theory treated as the fundamental atoms 

 of the universe. But it is evident that we can not begin there. They 

 have a history, marked perhaps by strange vicissitudes. Tiiey may be 

 agents of regeneration, but they are almost certainly products of de- 

 struction. Possibly they are seed as well as dust, and serve as the 

 nniterial link between the creation and decay of successive generations 

 of suns. 



The orhits of meteorites.— VvoL II. A. Newton, of Yale College, has 

 carefully studied the evidence available for determining the "former 



