ON DEW, &c. 135 



sometimes very abundant during it, an example 

 of which occurred to me on the night, common 

 to the 29th and 30th of July 1813 ; for on that 

 night, notwithstanding its shortness, more dew 

 appeared, than has ever been observed by me 

 on any other. 



In the last place ; I always found, when the 

 clearness and stillness of the atmosphere were 

 the same, that more dew was formed between 

 midnight and sunrise, than between sunset and 

 midnight, though the positive quantity of mois- 

 ture in the air, must have been less in the 

 former, than in the latter time, in consequence 

 of a previous precipitation of part of it. The 

 reason, no doubt, is the cold of the atmosphere 

 being greater in the latter, than in the prior 

 part of the night. 



But there are many circumstances, influ- 

 encing the quantity of dew, which, though 

 much more open to accurate observation, than 

 those tiitherto mentioned, are yet much less 

 easy to be understood. 



In my first attempts to compare the quantities 

 of dew formed during different times, or in dif- 

 ferent situations, I attended only to the appear- 

 ance, which it made on bodies having smooth 

 surfaces. But quickly seeing this method to 

 be very imperfect, I next employed wool to 

 collect dew from the atmosphere, and found it 



