THE BILTMORE PACHYMETER. 



In the case of trees standing (not felled), the mensuration of 

 tree diameters, with bark, at points other than breast height has 

 been found so troublesome, that little use is made of "upper 

 diameters" as factors of volume. 



The objects for which the measurement of upper diameters 

 along the bole of a standing tree may be desired, are, to find the 

 diameter at the end of the clear bole ; to find along the bole that 

 diameter, above which the tree ceases to be merchantable ; to find 

 Pressler's guide point, (one-half d. h. b.); to find the diameter 

 and the taper of the tree at any point desired ; to establish the 

 form factor and the form height, or number of cubic feet per foot 

 from the sectional area breast high as base. 



Upper diameters of standing trees are, usually, measured with 

 Pressler's telescope, with Wimmenauer's telescope, with Winkler's 

 and Klausner's instruments, or with the help of an ordinary 

 transit. In all cases, however, the use of the instrument is time 

 taking to such an extent that the American forester must much 

 prefer " to cut the tree down " when desiring to obtain its upper 

 diameters, instead of wasting time and mone}' in the use of in- 

 struments. 



The writer has constructed a simple device, based on a most 

 simple mathematical principle, which answers fully the purpose 

 of obtaining ' ' upper diameters. ' ' 



The mathematical principle involved in the use of the ' ' Bilt- 

 more Pachymeter" appears from the following equations; illus- 

 trated by the attached sketch : 



e^ _ I _ d 

 E~ L~ D 



The Biltmore Pachymeter is used in connection with a target 

 or piece of board graduated in inches, marked black and white, 

 which target is fixed horizontally at any point desirable at the 

 base of the tree. 



The instrument itself consists of a piece of metal about i8 

 inches long and i^ inches wide, containing a longitudinal slot 

 about }{ inch wide and 17 inches long. The edges of this slot 

 must be strictly parallel. Its actual width is entirel}' irrelevant, 

 from the mathematical standpoint. 



