Compute length of a limb or limb segment as the linear distance from point limb joins trunk to terminal point being measured.
1. Limb to be measured is represented by length L  
2. Find P1 by standing under P2, using clinometer and  
 moving and sighting up until a 90 degree angle is found.
 for the point P2. P1 is underfoot.  
3. H1, H2, D1, and h3 and segments thereofcan all be measured by
    standard ENTS methods/instruments. D1 is the level distance
     from tree to line segment P1P2.  
4. L is computed by the Pathgorean Theorem  
  L = SQRT(h32+D12).      
    ENTS tree measuring diagram prepared by Bob Leverett 9-28-2005