Hi John, Let me guess, you want to find good trees so you don't have to make any scarf joints?
There are several ways to find the height of a tree. One method is as follows.
1) Suppose that when standing the height of your eyes is 6 ft above the ground.
2) Find a point on the ground that is 44 feet away from the base of the tree and that is also level with the base of the tree.
3) While you are standing at this point look up at the tree so that you are sighting at exactly a 45 degree angle from level or plumb.
4) The point on the tree that you sighted will be 44 feet + 6 feet = 50 feet high.
5) Using this method you just move further away or closer to the tree until the imaginary line between your eye and the point you want to measure forms a 45 degree angle with level or plumb. Then you just add the height of your eye to the distance from the base of the tree. This assumes that the tree is vertical and that the ground is level.

How do you accurately measure your sighting angle? One way to do this would be to make a sighting device using a straight edge, string and weight (plumb bob), and a compass. Send me an email (piller@visi.net) for more info.
Chip