A number of different instruments can be used to determine height. With the exception of the Merritt hypsometer, all work on the same principle of taking two slope readings. The scales in each instrument are just housed in a different setting.
- Clinometer – as shown in Chapter 1
- Relaskop—see section 3.3
- Laser range finder/electronic hypsometer (these do the math for you!)
- Merritt hypsometer – illustrated below
Though not commonly used, the Merritt hypsometer on a Biltmore stick is an inexpensive tool for estimating tree height. It is based on the principle of similar triangles (Figure 2.15).