ON DEW, &c. 



grass was 12 and 14 colder than the air, there 

 was little dew; while on the night, which 

 afforded the most copious dew ever observed 

 by me, the cold possessed by the grass, beyond 

 that of the air, was for the most part only 3 

 and 4 ; and I have always seen less dew about 

 sunset, than about sunrise, when the weather 

 has been calm and clear at both times, though 

 there is commonly, in this country at least, a 

 greater difference between the temperature of 

 grass and of air in the evening, than in the 

 morning. I had early observed, also, bodies 

 exposed to the sky, on a cloudy but calm night, 

 to be sometimes 2 or 3 colder than the air, 

 without having any appearance of dew; and 

 when two metals possessing different relations 

 to dew were exposed together, I have seen the 

 one, which was the fitter to attract that fluid, 

 colder than the other, though both were dry. 



I shall conclude this part of my Essay, with 

 relating the results of some experiments, which 

 were made for the purpose of ascertaining the 

 tendencies of various bodies to become cold, 

 upon exposure to the sky at night. Unfor- 

 tunately, the weather was not always favourable 

 to my views ; but what occurred appears, to me, 

 notwithstanding, worthy of being related. 



