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lead, and placed near each other, three ftet above the furface of 

 the earth, and expofed to the full adion of the air, wind and fun. 

 I Colled. Acad. p. 142. But he adds, that when both were 

 placed in a room, within his houfe, the daily evaporation from 

 each was equal. 



In the firft experiment, a difparity of temperature feems to me 

 to have taken place during its continuance, which occafioned the 

 inequality of evaporation. The external air conftantly varies its 

 temperature : now fuppofing the initial temperature of both vef- 

 fels and of the water contained in them to be equal ; and fuppof- 

 ing the external air fome degrees hotter or colder than the water 

 jn thefe veffels, the fmaller of the two veiTels, and alfo the water 

 contained in it, muft have acquired the temperature of the air 

 fooner than the Vv'ater in the larger of the two, and thus its evapo- 

 ration muft fooner have been checked, as will prefently be fhewn 

 in treating of the influence of the temperature of the air, and this 

 check to evaporation muft have been renewed after every change in 

 the temperature of the air ; whereas, the water in the larger veflel 

 niuft have, during each change, acquired the temperature of the 

 air more flowly, a circumftance which promotes evaporation, as 

 v>'iil be fliewn. Therefore, in the fecond experiment within doors, 

 where the variations of the temperature of the air were fewer, or 

 none, the daily evaporation from each veffel was nearly equal. 



And 



