THE EVER-WIDENING WORLD OF STARS. 45 



the work by verifying Sir William's northern star-gaug- 

 ings. The eminent astronomer Struve and others have 

 applied a series of tests to the basis of Herschel's theory 

 of the universe. Increased telescopic power has been 

 applied to the examination of the nebulae. And lastly, 

 a mode of research more wonderful than the boldest 

 pioneers of science had ventured to hope for has been 

 applied to determine what the stars and nebulae really 

 are, nay even the very elements of which they are con- 

 stituted. 



Therefore we stand in a position so far in advance of 

 that to which it was in Herschel's power to attain, that 

 the attempt to modify his theories need no longer be 

 thought to savour of undue boldness. Half a century 

 does not pass without bringing a vast extension of 

 knowledge, and certainly the last half-century has been 

 no exception to this rule ; insomuch that could the 

 great astronomer take his place again among us, and 

 become cognisant of the vast strides which his favourite 

 science has made since he left us, he would be the first 

 to point out that many of his views require to be 

 modified or even to be wholly abandoned. 



For instance, let us consider the meaning of the 

 following observation made by the younger Herschel. 

 While 'sweeping' the southern heavens, this eminent 

 astronomer noticed occasionally the existence of faint 

 outlying streamers belonging to the Milky Way, not 

 only irresolvable into stars, but so exceedingly distant 

 that he could scarcely speak of them as really visible. 

 He was sensible of their existence, but when the eye 



