A HISTORY OF SCIENCE 



tic fluid, whether saturated or not with aqueous 

 vapor. 



"According to the theory, nothing is required for the 

 production of rain besides the mixture of portions of 

 the atmosphere with humidity, and of mixing the 

 parts that are in different degrees of heat. But we 

 have seen the causes of saturating every portion of 

 the atmosphere with humidity and of mixing the 

 parts which are in different degrees of heat. Conse- 

 quently, over all the surface of the globe there should 

 happen occasionally rain and evaporation, more or 

 less ; and also, in every place, those vicissitudes should 

 be observed to take place with some tendency to reg- 

 ularity, which, however, may be so disturbed as to be 

 hardly distinguishable upon many occasions. Vari- 

 able winds and variable rains should be found in pro- 

 portion as each place is situated in an irregular mixture 

 of land and water; whereas regular winds should be 

 found in proportion to the uniformity of the surface; 

 and regular rains in proportion to the regular changes 

 of those winds by which the mixture of the atmosphere 

 necessary to the rain may be produced. But as it will 

 be acknowledged that this is the case in almost all this 

 earth where rain appears according to the conditions 

 here specified, the theory is found to be thus in con- 

 formity with nature, and natural appearances are thus 

 explained by the theory." l 



The next ambitious attempt to explain the phenom- 

 ena of aqueous meteors was made by Luke Howard, in 

 his remarkable paper on clouds, published in the 

 Philosophical Magazine in 1803 the paper in which 



