Hi Rick "Always a comment" Dickson, The simple solution of chain/string etc is not sutiable as the user must enscribe a circle by walking arround the center point. Having to thread the chain through the trees and back again several times for each circle is not going to go down well at all. Thanks for the input though. Anton ---------- From: Rick Dickinson Sent: Thursday, November 13, 1997 5:41 PM Subject: Re: Forest Ranger Has anyone given any thought to the ultimate "low-tech" solution? Attach a piece of light chain (like used for dogs) to the top of a metal pole which is hammered into the ground. Or, actually use one of those dog chains which comes attached to a corkscrew-like metal stake which you twist into the ground. Have several links painted flourescent orange or green in the band between 740cm-760cm from the pole. Pull it tight next to the tree, and make your judgement. Much cheaper than surveying equipment, and simpler than an ultrasonic method. What do you think? - Rick "K.I.S.S." Dickinson --- You can help design a Serial Sonar Unit for model robots! Vist http://www.notesguy.com/notesguy for details, or send mail to Rick Dickinson at rtd@notesguy.com