DEW. 205 



A. The shady head of the tree both 

 arrests the radiation of heat from the 

 earth, and also radiates some of its own 

 heat towards the earth; and, therefore, 

 the ground (underneath a tree) is not 

 sufficiently cooled down to chill the 

 vapour of the air into dew. 



Q. Wtiy is there never much DEW at the foot 

 of WALLS and HEDGES ? 



A. 1st Because the wall or hedge 

 acts as a screen, to arrest the radiation 

 of heat from the earth : and 



2ndly The wall or hedge also 

 radiates some portion of heat towards 

 the earth. 



Q. How do these things prevent the deposition 

 of dew? 



A. As the ground (beneath a wall, 

 tree, or hedge) is not cooled by the 

 radiation of heat, it remains of the same 

 temperature as the air above it ; in 

 consequence of which, the vapours of 

 the air are not chilled by it into dew. 



Q. Why is there little or NO DEW beneath a 

 FLOWER-AWNING, although that atoning be open on 

 all four sides ? 



T 



