Height Finder

(for forest valuation surveys), an instrument for measuring the height and angle of inclination of standing timber. Height finders are subdivided into mechanical, optical-mechanical, and optical types. The mechanical type—for example, the Makarov height finder—determines the height of trees after preliminary measurement of the base line (the distance from the tree to the observer) at 10 and 20 m with other measuring instruments; the optical-mechanical type—for example, the Bliume-Leiss height finder—operates with preliminary measurement of the base line at 15, 20, 30, and 40 m by means of optical distance-measuring equipment with a variable outer base line. These height finders are used in instrumental and visual-measurement timber valuation. Optical height finders—for example, the Forestry Distance and Height Finder (FDHF), which consists of a height finder and distance-measuring equipment with a constant inner base line—permit measurement of trees with base lines of 10-40 m. The FDHF is an all-purpose timber gauge which, in addition to measuring the height and angle of inclination of trees also measures the area of the cross sections of trunks, the diameter of a tree at any given height, and the number of trunks in a given area; it is also used to mark off test areas. Optical height finders are the most precise and are used in scientific research institutes and for measurement and inventory purposes.