Meteors. 109 



operations of nature were of the same 

 kind with those of art, the upper parts of 

 our atmosphere would be always involved 

 in a fog, by reason of the condensation 

 of the vast quantity which continually as- 

 cends thither : but so far is this from be- 

 ing the case, that in those elevated regions 

 to which the vapours continually ascend, 

 the air is much drier than at the surface 

 of the ground. 



From many experiments, indeed, it is 

 evident, that water, after being reduced 

 into a state of vapour, is capable of un- 

 dergoing a certain change, by which it 

 lays aside its fluidity entirely, and even 

 to appearance its specific gravity ; so 

 that it becomes, as far as we can judge, a 

 substance totally different from what it 

 was before. After water has attained to 

 this state, our inquiries concerning it 

 must in a great measure cease ; but as it 

 is not in the immediate product of evapo- 

 ration that rain has its source, and as va- 

 pours change their nature in the atmos- 

 phere, so as to be no longer sensible to the 

 hygrometer or to the eye, and do not be- 

 come vapour again till clouds appear, we 

 must acknowledge it to be very probable, 



