9-1 THE COLOUEEB STABS ABOUT KAPPA CRUCIS. 



Sir "William Herschel during liis early labours took a somewliat 

 similar view to Wright's, which he supported by his then 

 unequalled instruments and observations ; but in the progress of 

 his work he found many facts which could not be reconciled with 

 this theory ; he felt convinced that the stars in the Milky "Way 

 must be very differently scattered from those which are about us, 

 and that there were some objects " possessing a self-luminous 

 milky luminosity," possibly at no great distance from us. 



Sir John Herschel (Outlines, page 581), after a careful survey 

 of the Milky Way, says : — " And it would appear to follow that the 

 smallest visible stars appear as such, not b}'" reason of excessive 

 distance, but a real inferiority of size or brightness." 



In " Other Worlds than Ours," Proctor has shown that not 

 only is such a view probable, but that it is an ascertained fact, in 

 some cases taken at random amongst the stars. Eor so far as can 

 be ascertained, the two stars 61 Cjgni are not more than one- 

 third the size or bi'llliancy of our own sun, and are very much 

 nearer to us than Sirius, which is estimated as nearly three 

 thousand times as large ; and upon this and other considerations 

 he founds the opinion " that in the galactic circle we see countless 

 numbers of small stars in the same region as the large ones, and 

 that, probably, this region has generally a circular cross section, 

 but is made up of enormous " whorls," or sweeps of starry 

 matter, and that stars may, and probably do exist, beyond these 

 Avhorls far beyond the reach of our present or future telescopes." 



If we admit that there are great differences in the size of 

 visible stars, it will at once afford us a probable explanation of the 

 motion of the smaller stars composing this cluster ; for on this 

 supposition, which is in all probability true, we can easily con- 

 ceive that some of the small stars are the nearest to us, and 

 therefore, have a larger motion. But if, on the old view, we are 

 to remove them as far again from us at least as stars of the sixth 

 magnitude, or twenty times as far as the nearest stars, we cannot 

 conceive of any motion grand enough to account for such a 

 singular change ; and it leaves us still the new stars unaccounted 

 for. 



Olbors, the celebrated Grerman astronomer, held the opinion 

 that light was gradually extinguished in its passage through 

 space, and therefore, in every direction a limit of visibility must 

 be reached ; and Struve, the illustrious astronomer of Pulkowa, 

 considers the extinction of light proven by the circumstance that 

 the space-penetrating power of telescopes as calculated in the 

 ordinary way far exceeds its value as indicated by actual observa- 

 tion, and he found that the two might be reconciled by assuming 

 that light in its passage from the nearest fixed star was enfeebled 

 to the extent of one part in one hundred and seven ; and although 

 the assumptions made by Struve are generally considered inadmis- 



