VIII. Answers to the Obje£iions of M. de Luc with regard 

 to theTuEORY of Rain. By JjMEs HurTON,M.'D. 

 F. R. S. Edin. and Member of the Royal Academy of Agri- 

 culture at Farts. 



{Read by the Author y Dec. 3. 1787. J 



MDe Luc, in his Idees fur la Meteorologie, has made 

 • fome objedions to the Theory of Rain * which I had 

 the honour to lay before this Society. I fliall now endeavour 

 to anfwer thefe objedlions ; and hope the Society will forgive 

 me for taking up a little of their time and attention with this 

 fubjeft. The reputation of M. de Luc is fo well eftablifhed in 

 the republic of letters, that I muft not negledl remarks which 

 have the fandlion of fuch authority ; although, in the prefent 

 cafe, they appear to me to have come from a judge who was too 

 much preoccupied with a different fyftem. 



The queflion between us, according to M. de Luc's own 

 ftatement, is this, Whether or not, when two maffes of air of 

 different temperatures are mixed together, the humidity of the 

 new mafs is greater than the mean between the humidities 

 which the two maffes had feparately ? This I maintain to be a 

 phyfical truth, and M. de Luc refufes to admit it as a rule in 

 nature. 



I HAD eftablifhed this propofition, That, upon the fuppofition 

 of the evaporating power increafing with heat, but increafing 

 at a greater rate, the mixture of two portions of air, of different 

 temperatures and fufficiently faturated with humidity, would 

 produce a condenfation of water which might then become vi- 



fible.. 



* Tranfaftions of the Royal Society of Edin. Vol.1. N° 11. Phyf. CI. 



