30 THE BORDERLAND OF SCIENCE. 



But, after all, how aptly this * demonstrated fact' of 

 Sir John Herschel's fits in with the work of his father! 

 When we note how the views of the elder Herschel had 

 been gradually modified, and the course on which the 

 progression of his theories had led him, we see that the 

 fact discovered by the younger Herschel was only some- 

 what in advance of the point reached by the father, but 

 lies strictly in the direction along which he had been 

 progressing up to the very close of his career. Sir W. 

 Herschel had modified his views about unequal double 

 stars concluding that the fainter orb is physically 

 associated with the brighter one, instead of lying far 

 beyond it. He had modified his views as to star-groups 

 of various orders. He had given up the idea that our 

 star-system can be gauged regarding the great cloud- 

 masses of the Milky Way as real clustering aggregations 

 of stars, instead of depths extending far out into space 

 and owing their seeming richness only to such exten- 

 sion. He had come to regard many star clusters as 

 part and parcel of the Milky Way, and large numbers 

 of nebulae as vaporous masses lying far within its limits. 

 It seems impossible to question how he, at least, would 

 have regarded the discovery made by his son. He 

 would have felt, I conceive, that so far as the evidence 

 went, the sole remaining objects which could till then 

 be regarded as external galaxies, must no longer be 

 so regarded, that these, like so many objects which he 

 had himself dealt with, must be looked upon as among 

 the wonders of our own star-depths. Nor do we think 

 that in arriving at this conclusion, in making this 



