Barry Heimlich offers this elegant solution, and a new use for Google (guess I don't need to find my old slide rule). Thanks, Barry!

**Get a scope or a sextant that has an angle scale to determine the angle from viewing point. Estimate the distance between viewing site and base of tree using Google maps. Calculate the height by calculating by trigonometric equation:
**

where H = height, L = distance from viewing site to tree, and = the tangent of the angle , which can be looked up on a trigonometric table or by Googling the term . If = 20o for example, Google “tan 20 deg”. It equals 0.36

Barry N Heimlich