

II. The THEORY of RAIN. By JAMES HUTTON, M. D. 

 F. R. S. EDIN. and Member of the ROYAL ACADEMY of 

 AGRICULTURE at PA R i s. 



PART I. 



Invejligation of the Law of Nature, on which is to be founded a 

 Theory of Rain. 



[Read by the Author , Feb. 2. 1 784.] 



THERE is ail atmofpherical appearance which is not explain- 

 ed by the known laws of heat and cold. It is the breath 

 of animals becoming vifible, in being expired into an atmo- 

 fphere which is cold or moift ; and the transformation of tranf- 

 parent fleam into the ftate of mift, when mixed with air which 

 is of a colder temperature. Natural philofophers have certainly 

 confidered thefe appearances as being explained in the general 

 law by which heat and cold are communicated among contigu- 

 ous bodies, otherwife they would have endeavoured to point 

 out this particular law, which feems to depart from a more ge- 

 neral rule, or does not follow the natural courfe of things ob- 

 ferved on other occasions. The fubjedl of this paper is to in- 

 veftigate a certain rule which, in the cafe now mentioned, may 

 be difcovered as directing the action and effects of heat and 

 cold ; and to form a theory of rain upon that invefligated rule, 

 concerning the evaporation and condenfation of water. 



THE air, infpired by an animal, may be confidered as a men- 

 ftruum diffolving water upon the warm and humid furface of 

 the lungs, and as thus becoming faturated with humidity in 

 this degree of heat. When this folution is again cooled, then, 



F according 



