

SPIRAL WONDERS OF THE UNIVERSE. ^Vw'il^ 



William H. Knight. ^OTaHKAJL 



QAIOMH 



A PONDEROUS, highly-illustrated, quarto volume has just been is- 

 sued by the Lick Observatory. A large section of it is devoted 

 to that little-known but fascinating department of astronomical re- 

 search — the Spiral Nebulae. These objects, so exceedingly small 

 from a human point of view, were first classed among the nebulae 

 because of their hazy appearance, but, as a matter of fact, they are 

 not nebulae at all, but each is a great aggregation of suns, some of 

 them comparable in extent with our own vast assemblage of suns, 

 clusters, and the encompassing Milky Way, which we have been 

 accustomed to designate the Siderial Universe. 



Why are these objects called "spiral" nebulae? Because many 

 of the nearer ones which come well within the range of our great tele- 

 scopes, are seen to have spiral convolutions, as if, when undergoing 

 the process of condensation into suns from the vast nebulous fields 

 trillions of miles in extent, whence they were derived, they were 

 whorled into a succession of rings, each smaller than the preceding, 

 giving a pyramiidal or cone-like effect. 



There is another singular peculiarity frequently observable in 

 the spiral nebulae. When seen edgewise they show a dark line run- 

 ning down the whole length of the spiral. This is generally explained 

 as due to a band of absorbing or occulting matter. But the nature of 

 this band, broad enough to be seen at this great distance, is a great 

 mystery. It is again singular that these dark lines are most marked 

 in those spirals which are apparently seen edgewise. 



According to E. E. Barnard of the Yerkes Observatory, we have 

 instances of occulting matter in certain regions of our Milky Way. 

 These black spots were formerly regarded as holes, through which we 

 could peer into vacuity, but there is now a consensus that these black 

 patches are due to intervening, obstructing, non-luminous nebulae, 

 which hide the stars beyond. 



Many of these spiral nebulae may be in early stages of develop- 

 ment, suns just emerging from formless chaos, surrounded by circling 

 planets, and these all ablaze like miniature suns, as was the earth 

 while its glowing igneous rocks prevented the enveloping aqueous 

 vapor from falling in rain to fill the hollows of our present ocean 

 beds. Doubtless other spirals are still further advanced to that stage 

 which enables the planets surrounding their suns to become habitable 

 worlds, thronged with intelligent beings, whose astronomers gaze with 

 wonder upon our own mighty Gallactic system, and speculate upon 

 the possibility of their habitability. The thoughtful mind reels with 

 the mental pictures which overwhelm it. 



Consider our Milky Way — an enormous assemblage of suns form- 

 ing a stream of worlds extending clear round our celestial vault, a 



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