TRANSLATOR'S INTRODUCTION Ixxvii 



' Now, how would these rings of vapour behave ? As they 

 cooled off their denser materials would condense first, and 

 thus the ring would be composed of a mixed mass, partly 

 solid and partly vaporous, the quantity of solid matter 

 constantly increasing, and that of vapour diminishing. If 

 the ring were perfectly uniform, this condensing process 

 would take place equally all around it, and the ring would 

 thus be broken up into a group of small planets, like that 

 which we see between Mars and Jupiter. But we should 

 expect that in general some portions of the ring would be 

 much denser than others, and the denser portions would 

 gradually attract the rarer portions around it until, instead 

 of a ring, we should have a single mass, composed of a 

 nearly solid centre, surrounded by an immense atmosphere 

 of fiery vapour. This condensation of the ring of vapour 

 around a single point would have produced no change in 

 the amount of rotary motion originally existing in the ring ; 

 the planet, surrounded by its fiery atmosphere, would there- 

 fore be in rotation, and would be, in miniature, a reproduc- 

 tion of the case of the sun surrounded by his atmosphere 

 with which we set out. In the same way that the solar 

 atmosphere formed itself first into rings, and then these 

 rings condensed into planets, so, if the planetary atmospheres 

 were sufficiently extensive, they would form themselves into 

 rings, and these rings would condense into satellites. In the 

 case of Saturn, however, one of the rings was so perfectly 

 uniform that there could be no denser portion to draw the 

 rest of the ring around it, and thus we have the well-known 

 rings of Saturn. 



' If among the materials of the solar atmosphere there 

 were any so rare and volatile that they would not unite 

 themselves either into a ring or around a planet, they would 

 continue to revolve around the sun, presenting an appearance 

 like that of the Zodiacal light In accordance with 



