aIso in its central portion. In this one of Ursa Major you see 

 A double croAvn with two brilliant nuclei and a fringed border. 

 The nebulas Ave have so far dealt with are, as Ave knoAV by 

 .spectrum analysis, mainly composed of incandescent gas. They 

 lie, as I have said, far beyond the limits of our solar system. 

 Their distance is incalculal^le, unimaginable. Great changes have 

 "been proved to take place in them. Scattered over most of them 

 Are brilliant points of light were the gaseous atoms are condensed 

 into masses of intense brilliancy, and doubtless enormous size. 



Are these glittering nuclei suns 1 Do Ave Avatch here the 

 growth of a world-controlling luminary similar to the great centre 

 of our OAvn system 1 The question is not finally ansAvered. Yet 

 in the remarkable changes which the nebula surrounding a well- 

 knoATO star in the constellation Ai'gus seem to favour such a 

 vieAv. In the opinion of the astronomer at Mell^ourne, the star 

 increases at the expense of the nebula surrounding it. Far as 

 these luminous clouds are beyond our system, yet it must be 

 remembered that the sun himself and the planets that circle romid 

 him are moAing through space at an enormous speed. Portions 

 of these fiery clouds would thus be brought Avithhi his influence, 

 and be forced to revoh'e round him. A neAv comet would come- 

 within the ken of the dAvellers on this spot of earth, and some 

 ^ cooled, condensed fragments might find their AA^ay to its surface. 

 [But there are nebulae undoubtedly composed of A^ast numbers of 

 fgloA\-ing liquid or solid bodies, and among all the Avonders of 

 j.the sky feAv are more Avonderful, more suggestive than these, 

 lUegard for a moment this prodigious spiral of stars. Look at 

 tliis brilliant mass in its centre. Under a poAverful telescope 

 these drifting masses of seeming cloud resolved themselves into 

 star-streams. The atoms of this light-giving vapour are tliem- 

 j selves Avorlds. Here, again, are clusters of suns whose concen- 

 trated light, dimmed by enormous distance, seems to us but a 

 [faint luminosity. In the cluster in Hercules, here represented, 

 I there must be at least five thousand suns. Many of these were 

 [at one time thought to be clouds of luminous gas, but increased 



