56 ANSWERS to the OBJECTIONS 



wherein condenfation of vapour is formed, by mixing the at- 

 mofpheric air with that which had been rarefied, or by emitting 

 into the atmofphere air which had been condenfed. In all 

 thofe cafes, there is the mixture of two portions of the atmo- 

 fphere, in fufEciently different temperatures, to produce con- 

 denfation of humidity, which adlually happens. Thus, all 

 thofe appearances are properly explained by the theory, or, as 

 experiments, they confirm the aiTumed propofition. 



But if thus every particular example is a proof, and if each 

 example is unexceptionable in its kind, what degree of evidence 

 muft arife from the united teftimony of every poflible experi- 

 ment almoft which can be adduced in relation to the fubjedt ? 

 It is to be prefumed that M. de Luc, with all his extenfive 

 knowledge of nature, could not adduce one fhadow of a fadl 

 by which the alleged propofition could be called in queftion or 

 dlfproved. 



M. DE Luc concludes in the following manner, (parag. 588.) 

 " Je ne vois done rien dans ces faits, qui contribue a eclaircir 

 " la queftion de la pluie ; et par consequent elle me paroit 

 " refter au point ou je I'avois amene avant que d'entrer dans 

 " ce nouvel examen. Je tire meme du memoire du Dr Hut- 

 " TON, ces deux confequences, qui juftifient le travail que j'ai 

 " enterpris. Quoiqu'il paroiffe s'etre beaucoup occupe des 

 *' phenomenes de la pluie, aueune theorie a leur egard ne I'avoit 

 " fatisfait ; et d'apres ce qui lui etoit connu des loix de I'hygro- 

 " logic, il avoit conclu, que la precipitation de I'eau fimple- 

 " ment evaporee, ne pouvoit etre produite que par refroidiffe- 

 " ment. Or, ce font, entre autres, ces deux motifs qui m'ont 

 " conduit dans mes recherches." 



M. DE Luc had no occafion to juftify his undertaking by 

 any opinions of mine. His writings will always contain 

 matter fufficient to intereft the public ; and his ideas of hygro- 

 logy mufl be fupported upon their own bottom. I therefore 

 :!;vilh he had not given as my ideas expreffions which, however, 



in 



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