1. Measure the horizontal distance from the base of a vertical tree (or the position directly beneath the tree tip of a leaning tree) to a location where the required point on the tree (e.g. tree tip) can be seen.
   
   
2. Sight at the required point on the tree:
   
   
   • Using one eye: Close one eye and simultaneously look through the Suunto at the scale and 'beside' the Suunto at the tree. Judge where the horizontal line on the Suunto scale would cross the tree.
     
     
   • Both eyes: With one eye looking at the Suunto scale and the other looking at the tree, allow the images to appear to be superimposed on each other and read where the horizontal line on the Suunto scale crosses the tree. Note: If you suffer from astigmatism (a common situation where the eyes are not exactly parallel), use the one eye approach.
     
     
3. Read from the percent scale and multiply this percentage by the horizontal distance measured in step 1.
   
   
4. Site to the base of the tree and repeat steps 2 - 3.
   
   
5. Combine the heights from steps 3 and 4 to determine total tree height:
   
   
   • Add the 2 heights together if you looked up to the required point in step 2 and down to the base of the tree in step 6.
     
     
   • Subtract the height to the base of the tree from the height to the required point if you are on sloping ground and had to look up to both the required point and the base of the tree.
     
     
6. Check all readings and calculations.

[suunto.htm] Revision: 6/2001
Cris.Brack@anu.edu.au