THE YIELD OF A FOREST. 



15 



for a number of years, should be cut from the forest 

 in the corresponding period. Thus, if the growth or 

 increase is 100 cords a year, that amount might be har- 

 vested yearly by cutting every tree on a small area, by 

 cutting fewer trees per acre on a larger area, by dis- 

 tributing the cut every year over the whole surface of 



FIG. 8. Measuring an average tree. Adirondack Mountains, New York. 



the forest, or by cutting 1,000 cords in any one of 

 these ways once in ten years. 



There are many different methods of finding what 

 is the annual increase of wood in a forest. One of 

 the simplest is to count the number of trees upon an 

 acre and select an average tree, then to cut it down, 

 measure its cubic contents, and find its age by count- 

 ing the annual rings. That done, the yearly increase 



