VOLUME OF STANDING TREE. 



133 



hypsometer. A simple geometrical method is illustrated in the 

 figure. A measuring rod is set up at a convenient distance from 

 the tree AB, the eye of the observer is at S, and the lines of 

 sight to the top and bottom of the tree intersect the rod at a 

 and b. Then, by measuring the distances from the observer to 

 the rod and to the tree the height is given by the formula 



SD 



Now, considering the tree as a paraboloid, its basal area 

 times one-half the height will give approximately the volume. 



Figure 36. Measuring the height of a tree by a simple geometrical 



method. 



For example: A white pine has a diameter at breast height of 

 18.7 inches, and the height of the tree is eighty-four feet; what 

 is the volume? By reference to the table of areas of circles the 

 area corresponding to a diameter of 18.7 inches is found to be 

 1.0072 square feet. Multiplying this by one-half the height, the 

 approximate volume of the tree is found 1. 9072X42=80- IO2 4 

 cubic feet. 



The Volume of a Standing Tree may be Obtained 

 by Bmploying a Form Factor which h#s been previously 

 determined for that particular species by the felling and accu- 

 rate measurement of a great many sample trees of approxi- 



