ON DEW, &c. 125 



I fancied that I had collected information 

 worthy of being published; but fortunately, 

 while preparing an account of it, I met, by 

 accident, with a small posthumous work of Mr. 

 Six, printed at Canterbury in 1794, in which are 

 related differences observed on dewy nights, 

 between thermometers placed upon grass and 

 others in the air, that are much greater than 

 those mentioned in the paper presented by him 

 to the Royal Society in 1788. In this work, 

 too, the cold of the grass is attributed, in agree- 

 ment with the opinion of Mr. Wilson, altogether 

 to the dew deposited upon it. The value of 

 my own observations appearing to me now 

 much diminished, though they embraced many 

 points left untouched by Mr. Six, I gave up 

 my intention of making them known. Shortly 

 after, however, upon considering the subject 

 more closely, I began to suspect, that Mr. Wil- 

 son, Mr. Six, and myself, had all committed an 

 error, in regarding the cold, which accompanies 

 dew, as an effect of the formation of that fluid. 

 I, therefore, resumed my experiments, and 

 having, by means of them, I think, not only 

 established the justness of my suspicion, but 

 ascertained the real cause both of dew, and of 

 several other natural appearances, which have 

 hitherto received no sufficient explanation, I 

 venture now to submit, to the consideration of 



