

CAUSES OF DIMINISHED SUPPLY OF WOOD. 151 



kinds of trees grown under different conditions. Any 

 cycle determined solely by the produce required for 

 metallurgical operations may prove too brief for the trees 

 to yield the quantity of timber required ; and had the 

 cycle in this case been one of twenty-five years, instead of 

 one of forty years, the result might have been different. 



