Biltmore Stick
n
- A ruler that is held at prescribed distances from the body. The stick’s four faces are scribed with lines and numbers. These lines and numbers are used to estimate tree diameter and tree height, and ultimately tree volume.
Synonyms: none known to the author.
Biltmore Sticks date back to the mid-18th century and use geometric principles to estimate a tree’s height and diameter. The face used to measure tree height has two scales: one for estimating height from one chain’s distance (66 feet) and the other (for taller trees) requiring a distance from the tree of one-and-a-half chains (about 100 feet).
References:
Steve Nix at Forestry.About.com has a good explanation of how a Biltmore Stick works at About.com.
You can make your own tree measuring device. Here’s a Perdue University PDF on making one.
Nullius in Verba 
Aha! I already know this one…from long ago on the YouWriteOn message board :o)
Yes, indeedy you do. I’ll wager you’ve not built one for yourself yet.
I wish I could find a public commons picture of a Biltmore stick. I wandered about looking for a picture… ‘Spose I could put in some links to pictures… [blog’s author wanders off muttering to himself]