124 THE EVOLUTION OF SATELLITES. 



But a photograpli of this object sliows that the system really consists 

 of a luminous globe surrounded by a thick and less luminous ring, and 

 that the opacity of the sides of the ring takes a bite, as it were, out of 

 each side of the disk, and so gives it the apparent form of a dumb bell. 

 In this case the rotation must be about an axis at right angles to the 

 ring, and therefore along the length of the dumb-bell.^ 



From what I have said it must be obvious that the subject is sur- 

 rounded by difficulties and uncertainties. Mr. See is therefore to be 

 congratulated on having laid before the world an hypothesis which 

 appears to explain the facts as far as we know them. The subject is 

 necessarily a speculative one, and we must look forward to future 

 spectroscopic and photographic researches for the confirmation or refu- 

 tation of his theories. 



' It is proper to state that Mr. See does not refer to this uebula as confirmatory of 

 his theory. 



