THE BILTMORE STICK 



301 



THE BILTMORE STICK 



This implement, employed to ascertain the diameter of 

 standing timber when held at arm's length tangent to the 

 trees to be measured, was briefly described on page 163. 

 Relations between tree, stick, and eye when the stick is 

 in use are made clear in the figure, the circle representing 

 a section of a tree -breast high, B X the Biltmore stick, 

 A T the distance from the stick to the eye, and M a 

 radius vertical to the line of sight passing on one side of 

 the tree. With this for a pattern it is clear how the woods- 

 man, after having determined A T as a matter of practice, 

 can plot circles of different diameters, draw tangents to 

 them from A, and ascertain by measurement in each case 

 B C, the proper stick graduation. 



The geometry of the matter is that of similar right- 

 angled triangles, and consideration will show the soundness 

 of the formula appended, from which may be derived 



AT(AT+D) 



the value of B C for circles of any size and for any arm 

 reach. When .the latter, A T, has been determined by 

 trial, the formula becomes simpler. Thus with A T = 25 



BC 



25 D 



or, for D = 10 inches 



V25 (25 + D) 

 250 250 



V625 + 250 29.58 



= 8.45 inches. 



Values of B C for tree diameters from 6 to 60 inches and 

 distances of 23 to 27 inches have been worked out and 

 are published in the- "Proceedings of the Society of Amer- 

 ican Foresters " for 1914, page 48. 



