112 OF EVAPORATION. CHAP. 2. 21. 



contributes to equalize the vespertine with the 

 diurnal temperature, and to make the change 

 more gradual. The formation of clouds may 

 be regarded as dependent on circumstances 

 which attend this process ; for the rising of 

 the elastic vapour impels that above into an 

 atmosphere already too cold for its solution, 

 which, therefore becomes cloud, as explained 

 before. 



As the particles of a cloud, for example a 

 cumulus, are not believed to be kept separate by 

 the same power of repulsion as those of elastic 

 vapour, and as clouds are electrified, so we 

 ascribe the mutual repulsion of their corporeal 

 particles to that of similarly electrified bodies : 

 now, according to Newton, where repulsion 

 ends, there attraction begins ; and if by the 

 joint influence of these two powers, the cumulus 

 is kept together as an aggregate, while its 

 particles do not unite, so as to form water, we 

 must suppose that the same principle holds 

 good with respect to electrical attraction and 

 repulsion. After all, these are merely theories, 

 against which there appear as many reasons as 

 there are for them. The inquisitive jnind of 

 man is always seeking for causes, and making 

 systems, by which even the most incredulous 



