Clinometer with tan functions (% scale)
Many student-made clinometers are measured in degrees. The image of the clinometer that you can download is expressed in tan. The tan function can also be expressed as a % function. If you are measuring tree heights, and you stand 10 meters from the tree, the tan clinometer will express the height as a % of the 10 meters from the tree. You can also look to the base of the tree and get a distance your eye is from the base of the tree. This should be added onto the height to the top of the tree.
You can make your own tan clinometer by downloading the image to the left, and printing the image on adhesive vinyl (two to a sheet). Then put the vinyl on a metal surface, cut the metal to shape, with two small drill holes in the top edge of the clinometer, turn these to 90 degrees and use them for sighting. Suspend a bicycle spoke from a hole drilled at the apex and weight the spoke with a fishing weight that can be bent along the spoke.