22 



Forest Mensuration 



lay claim to correctness in many cases. For instance: The cubic con- 

 tents of a tree are supposed to be equal to 

 TT D 2 X H X F 



7 X -- IS" 



After Paragraph XXVII., 2, these contents are also 



= D' X 78 X H X F 

 5 



288 

 H X F = - =37 



7.8 



As a matter of fact, the form height of trees I foot to 2 feet in diam- 

 eter is close to 37. And for such trees the equation holds good. 



The form height may also be defined as "volume (standards, cords, 

 bark, etc.) per square foot of sectional area chest-high." 



PARAGRAPH XXXII. 



MEANS FOR EXACT MENSURATION OF STANDING TREES. 



The means used to find the exact solid volume of standing trees are 

 instruments for measuring the total height of the merchantable length 

 of a tree ; instruments for measuring the diameter at given heights ; fur- 

 ther tables based on scientific research and experience, or tables merely 

 meant to facilitate calculation. Instruments for measuring diameters far 

 above ground are needed for the use of the formulas given by Riecke, 

 Hossfeldt, Pressler, etc. 



The six paragraphs following next dwell upon these topics. 



PARAGRAPH XXXIII. 



MEASURING THE HEIGHT OF A STANDING TREE. 



The height of a tree can be measured by comparing its shadow with 

 the shadow of a stick, say 10 feet long. The "Lumber and Log Book" 

 gives another old method (page 133) of height measurement. If the 

 observer places himself in such a way that a small pole stands between 

 him and the tree at a distance e, and if he marks on the pole two points 

 where his sight, directed towards the top and base of the tree, touches 

 the small pole, and if he further ascertains the distance E separating him 

 from the tree, then the height of the tree H equals 



wherein b represents the number of feet between the two points marked 

 on the pole. 



