EVAPORATION. 161 



4thly Because the vast forests are 

 cut down. 



Q. Why do HEDGES and BELTS of TREES 

 promote WARMTH ? 



A. Because they retard evaporation, 

 by keeping off the wind. 



Q. If belts of trees promote WABMTH, why do 

 FORESTS produce COLD ? 



A. 1st Because they detain and 

 condense the passing clouds : 



2ndly They prevent the access of 

 both wind and sun : 



3rdly The soil of forests is always 

 covered with long damp grass, rotting 

 leaves, and thick brushwood : and 



4thly There are always many hollows 

 in every forest full of stagnant water. 



Q. Why do LONG GRASS and ROTTING LEAVES 

 promote COLD ? 



A. Because they are always damp; 

 and the evaporation which they promote, 

 is constantly absorbing heat from the 

 earth beneath. 



Q. Why do DIGGING and PLOUGHING help to 

 make a country WARM ? 



A. Digging and ploughing help to 



P3 



