I am an elementary school teacher in search of information about using a Biltmore stick, and a clinometer. I really need conversion charts for board feet and angle conversion for tree height. Anything will be helpful. Thanks

Reply to post by Tim Dotterer, on June 01, 2000 at 21:46:16:

There's a helpful file on the Biltmore Stick on the Tech Reports pages of this site (link in header, and below). Includes instructions on making custom Biltmore Sticks.

Measuring height with the stick is a simple trig problem, although that is probably beyond elementary school level. A formula is given in the file above.

If you are measuring angles with a clinometer, you just need some geometry and trig (see diagram). The height of the tree is found from
H = (d x tan A) + Ob

H - Height
d - distance from tree to observer.
A - angle from horizontal to tree top.
Ob - height of observation above the ground (eye level)

Reply to post by Russ Carlson, on June 01, 2000 at 21:46:16:

Forgot to include ground slope. The easiest way to do this is to simply take a measurement for eye level to the base of the tree, and to the math again for this second sighting. Add the two figures together for the total height (instead of adding the observer's eye height). This methods corrects for moderate slopes, as long as 'd' is measured horizontally.