The Suunto Clinometer (clino) is a tool commonly used by foresters to measure tree heights and also slope angles. At the rear of the clino is a peephole, which shows a percentage scale and a horizontal line.

1. First measure the horizontal distance between the base of the tree and the operator.
2. Looking through the peephole, line up the horizontal line with the top of the tree and read off the corresponding number from the percentage scaIe, which is on the right hand side. The scale on the left is in degrees and should not be used!
3. Line up the horizontal Iine with the base of the tree and again read off the corresponding number from the percentage scale.
4. If the base of the tree is above you (i.e. you're on the downward slope) then subtract the number from Step 3 from the number from Step 2 and multiply by the horizontal distance to get a total tree height.
5. If the base of the tree is level with you or below you (i.e. you're on the upward slope) then add the numbers together and multiply by the horizontal distance to get a total tree height.
6. If the tree is leaning, stand at right angles to the lean so the tree isn't leaning towards or away from you.

Tree height is measured using the principle of triangulation with a clinometer. Of all the forestry tools you will use, the clinometer requires the most practice and skill. Assuming that the tree grows at a right angle to the ground (even on a slope).