ON DEW, &c. 129 



If, in the course of the night, the weather, 

 from being calm and serene, should become 

 windy and cloudy, not only will dew cease to 

 form, but that, which has formed, will either 

 disappear, or diminish considerably. 



In calm weather, if the sky be partially co- 

 vered with clouds, more dew will appear, than 

 if it were entirely covered, but less than if it 

 were entirely clear. 



Dew probably begins, in this country, to ap- 

 pear upon grass, in places shaded from the sun, 

 during clear and calm weather, soon after the 

 heat of the atmosphere has declined. My op- 

 portunities, however, for making such observa- 

 tions have not been numerous, since, while 

 pursuing this subject, I seldom went into the 

 country, till late in the afternoon ; but I have 

 frequently felt grass moist, in dry weather, 

 several hours before sunset. On the other 

 hand, I have scarcely ever known dew to be 

 present in such quantity upon grass, as to ex- 

 hibit visible drops, before the sun was very near 

 the horizon, or to be very copious, till some time 

 after sunset. It also continues to form, in 

 shaded places, after sunrise; but the interval 

 between sunrise, and its ceasing to form, is, 

 according to my observation, which, upon this 

 point, has not been extensive, considerably 

 shorter, than that between its first appearance 



