Atmosphere,, 105 



56 65536 



63 262144 



7O 1048576 



By pursuing these calculations, it 

 might be easily shewn, that a cubic inch of 

 the air we breathe would be so much 

 rarefied at the height of 500 miles, that 

 it would fill a sphere equal in diameter to 

 the orbit of Saturn. Hence we may per- 

 ceive how very soon the air becomes so 

 extremely rare and light, as to be utterly 

 imperceptible to all experience ; and that 

 hence, if all the planets have such atmos- 

 pheres as our earth, they will, at the dis- 

 tances of the planets from one another, 

 be so extremely attenuated, as to give no 

 sensible resistance to the planets in their 

 motion round the sun for many, perhaps 

 hundreds or thousands of ages to come. 

 Even at the height of about fifty miles, 

 it is so rare as to have no sensible effect 

 on the rays of light. 



Mr. Boyle in his physico-mechanical 

 experiments concerning the air, declares 

 it probable that the atmosphere may be 

 several hundred miles high ; which is 

 easy to be admitted, when we consider^ 

 what he proves in another part of the 



