28 THE BORDERLAND OF SCIENCE. 



has seemed willing to do. Yet we must not forget that 

 it was a peculiarity of Sir John HerscheFs mode of 

 dealing with such matters, that he did not press facts 

 home very strongly. He had not, indeed, a firm grasp 

 of facts. Again and again in his published works we 

 find him reasoning in absolute forgetfulness or as if in 

 absolute forgetfulness of facts he had already demon- 

 strated or admitted. He differed in this most mark- 

 edly from his father, who never once let go his grasp 

 of a fact. Both these great men had a light hold of 

 theories, but the elder Herschel had at the same time 

 a vice-like hold of facts, Sir John Herschel not un- 

 seldom let them slip through his fingers. 



I therefore confidently urge the 'demonstrated fact' 

 spoken of by Sir John Herschel, as 6 a conclusion which 

 must inspire' something more than * caution in admitting' 

 the consequences which had been supposed to flow from 

 the elder Herschel's studies of such irresolvable nebulae 

 as he did not consider to be gaseous. Sir W. Herschel 

 had judged that multitudes of these nebulae must be 

 external Milky Ways ; the ' demonstrated fact ' is that 

 a large group of such nebulas happening to be so placed 

 that their distance (relatively to isolated stars) can be 

 estimated, are not external galaxies, but much nearer 

 to us than many parts of our own galaxy. In the only 

 cases in which we can judge, these star-cloudlets are 

 found not to be external star-systems; is not this a 

 ground for something more than caution as to the 

 theory that in the other cases, where we have no means 

 of judging, such star-cloudlets are certainly external 



