DIAMETERS OF STANDING TREES 3 



The Calipers. — See that the calipers are in adjustment. If 

 •they are, the closed arms will just fit together nicely when the 

 handles of the arms* are pressed together. It they are out of 

 adjustment, adjust by means of the set screw on the movable 

 arm. In using the calipers he sure that the movable arm is -pressed 

 hack against the scale-beam, and that the scale-beam is placed against 

 the tree. This will lessen inaccuracies due to the arm being out of 

 adjustment. In calipering a large number of trees care is also 

 necessary that the measurements be taken at a point 4.5 feet 

 (D.B.H.) above ground. 



The Biltmore Stick is based upon similar triangles, and assumes 

 that the trees are perfectly round in circumference. To measure 

 a diameter with this instrument place the stick flat against the tree 

 at the point where the diameter is to be measured, being careful 

 tha^ it is held horizontal and perpendicular to the line of sight 

 from the eye to the center of the tree. The eye should be arm's 

 length, 25 inches, from the stick. Move the stick to right or 

 left until the line of sight from the eye to the edge of the tree passes 

 over the zero end of the stick. The diameter is then read where 

 the line of sight to the opposite side of the tree strikes the stick. 

 . In making the reading be careful that the head is not moved and 

 that the stick is not placed on a ridge or in a depression of the 

 bark. 



The Diameter Tape. — No especial directions concerning the 

 use of the diameter tape should be necessary. If a diameter tape 

 is not available use an ordinary tape graduated into feet and tenths 

 and divide by tt. Reduce to inches by multiplying by 12. 



The Dendrometer .—Since the types of dendrometers available 

 are so varied special directions for using will have to be given by the 

 instructor. In this connection the author has devised and exten- 

 sively used an instrument termed a "tree cross" which is based 

 upon the principle of the Biltmore stick except that the scale is 

 attached by means of a sliding and swiveling joint fifteen inches from 

 the end of a staff which is sixty inches long. The measurement is 

 taken by placing the end of the staff nearest the scale against the 

 cheek, the other end against the tree pointing towards the center 

 and reading the scale as is done with the Biltmore stick. 

 Tally the measurements of each tree according to the following form 

 of notes: 



Tree Ocular Diameter Biltmore Dendrom- Tree 



No. estimate tape stick eter calipers 



When all measurements have been taken on the 20 trees, add up 

 the total inches in each column; find the difference between each 

 one of these totals and the total value secured with the calipers. 



