ON DEW, c. 139 



upon the same grassplat, in the direction of the 

 wind, as well as this could be ascertained. I 

 then laid 10 grains of wool on the middle of 

 that part of the grass, which was sheltered by 

 the roof, and the same quantity on another part 

 of the grassplat fully exposed to the sky. In 

 the morning, the sheltered wool was found to 

 have increased in weight only 2 grains, but 

 that, which had been exposed to the sky, 16 

 grains. 



In these experiments, the view of the sky 

 was almost entirely cut off from the situations, 

 in which little dew was formed. In others, 

 where it was less so, the quantity gained, was 

 greater. Thus, 10 grains of wool, placed upon 

 the spot of the grassplat, which was directly 

 under the middle of the raised board, and which 

 enjoyed, therefore, a considerable oblique view 

 of the sky, acquired during one night 7, during 

 a second 9, and during a third 12 grains of 

 moisture, while the quantities gained, during 

 the same times, by equal parcels of wool, laid 

 upon another part of the grassplat, which was 

 entirely exposed to the heavens, were 10, 16, 

 and 20 grains. 



As no moisture, falling like rain from the at- 

 mosphere, could, on a calm night, have reached 

 the wool in any of the situations, where little 

 dew was formed, it may be thought, that the 



