174 



FORESTRY IN NEW ENGLAND 



fifteen years for hemlock under similar conditions to reach the 

 height of two feet, then the total age of the tree will be esti- 

 mated to be one hundred and seventy-five years. 



By permission of S. J. Record. 

 Fig. 64. — Cross section of a hardwood (black ash) highly magnified showing the annual 

 rings of growth. A to B is one season's growth. 



2. Diameter Growth. 



For scientific purposes diameter growth should always be studied 

 at a cross section taken at breast height, but as a matter of fact 

 it is usually studied on the stumps of trees cut for lumbering. 

 As the growth near the swelHng of the roots is slightly greater 

 than that higher up, the results are not entirely accurate. The 



