J 98 WILLIAMSON ON COMETS. 



It being clear that an atmosphere is necessary to vegetable and to 

 animal life, and it being pretty clear, as I think, that every planet and 

 every comet is surrounded by an atmosphere, and that every planet and 

 every comet enjoys as much of an atmosphere, in all situations, as is 

 sufficient to preserve a moderate temperature for all its inhabitants, we 

 are bound to believe that as those globes are obviously fitted to be the 

 habitation of rational creatures, they are certainly inhabited. 



What ideas are we to form concerning the rank of the several inha- 

 bitants of those globes, in the scale of intellectual beings? On this 

 subject we have only to observe, that if the length of their several lives, 

 or the extent of their intellectual attainments, be at all proportioned to 

 the length of their years, or the magnitude of the globes they inhabit, 

 many of them might regard us with pity. The comets are of various 

 sizes, and their years from seventy-five of ours to five or six hundred. 

 The comet of 1744 was about twenty-seven times the bulk of this globe. 

 The planet Jupiter, whose year is equal to twelve of our years, is more 

 than six hundred times the bulk of this globe. 



When we speak of comets wandering to the distance of twelve thou- 

 sand millions of miles from the sun, it may be objected that at such a 

 distance they would certainly interfere with some other systems. But 

 we are to consider that it appears, from correct observations, that the 

 nearest fixed star must be at a greater distance from us than four hun- 

 dred thousand times ninety-four millions of miles, which is the distance of 

 the sun from the earth. Thus it appears that a comet must travel at 

 least sixteen hundred times the distance mentioned before it could 

 arrive at the central space between our sun and the nearest luminary of 

 another system. It will follow that light must be above two thousand 

 two hundred days in coming from the nearest fixed star. 



Having ventured an opinion that every planet and every comet in our 

 system is inhabited, we have only taken a very imperfect view of the 



