of the Heaveulj/ Bodies. 21 



A ray of light, passing perpendicularly, at equal oTstdnces', 

 between the particles of each series, and successively through 

 many series of particles, concentrically, and more and more 

 numerously arranged in different successive planes, will be 

 attracted by, and inflected towards the planes, in which the 

 greater number of particles are disposed. 



A ray of light passing obliquely and successively, through 

 and between various concentric series of particles in various 

 planes, and of variously increasing numbers in those planes, 

 will be inflected and bent, into directions compounded of the 

 directions given by the succeeding different planes and con- 

 centric series, conformably to the established laws of motion. 



The body of air, incumbent upon the earth and its waters, 

 acting by its powers of solution becomes more or less charged, 

 more numerously at small, less numerously at greater distances 

 from the surface, with particles of water floating in it, in states 

 intermediate between absolute solution and rapid precipitation. 

 These particles in a further state of separation from, and floatage 

 in the air, are congregated into visible forms, and become fogs 

 and clouds. In the intermediate state between perfect solution 

 and visible separation, though they do not entirely destroy the 

 transparency of the atmosphere, they yet exist in the air as 

 floating detached bodies, capable of acting upon light by re- 

 flecting and inflecting it, and show their existence and powers 

 frequently, by exhibiting the tracts of the sun-beams passing 

 from between clouds through the air, or by otherwise variously 

 acting upon objects seen through the vapours which they 

 compose. 



By the observation of those who ascended Mont Blanc, and 

 were terrified at the black apparent void beyond the top, there 

 were then no particles in the air, higher than the mountain, 

 capable of reflecting light. Mont Blanc is not quite three miles 

 above the level of the sea. Seldom higher than this, above the 

 level of the surrounding region, can the vapours of flat countries 

 be considered to rise, so at least as to become sensible by their 

 actions on light, and to this height must be reduced the great 

 concentric masses of sensible vapours supposed to be from fifty 



