STAR-GROUPING, STAR-DRIFT, 

 AND STAR-MIST. 



A Lecture delivered at the Royal Institution on May 6, 1870. 



NEARLY a century has passed since the greatest astronomer 

 the world has ever known the Newton of observational 

 astronomy, as he has justly been called by Arago 

 conceived the daring thought that he would gauge the 

 celestial depths. And because in his day, as indeed in our 

 own, very little was certainly known respecting the distribu- 

 tion of the stars, he was forced to found his researches upon 

 a guess. He supposed that the stars, not only those visible 

 to the naked eye, but all that are seen in the most power- 

 ful telescopes, are suns, distributed with a certain general 

 uniformity throughout space. It is my purpose to attempt 

 to prove that as Sir Wm. Herschel was himself led to 

 suspect during the progress of his researches this guess was 

 a mistaken one ; that but a small proportion of the stars can 

 be regarded as real suns ; and that in place of the uniformity 

 of distribution conceived by Sir Wm. Herschel, the chief 

 characteristic of the sidereal system is infinite variety. 



In order that the arguments on which these views are 

 based may be clearly apprehended, it will be necessary to 

 recall the main results of Sir. Wm. Herschel's system of 

 star-grouping. 



Directing one of his 2o-feet reflectors to different parts of 



