This clinometer, is a hand-held optical scientific instrument used in surveying to measure vertical angles. It is used to measure the angle of elevation from the ground in a right-angled triangle. It may have been used by a surveyor or a forester to measure the height of tall things where you couldn't possibly reach to the top of e.g. flag poles, buildings or trees.This item is an example of an early hand held measuring instrument.. Today the use of electronic sensors is an important component in the design and function of the clinometers.A rectangular wooden folding measuring instrument. the panels are brass framed. Inside is a brass semi-protractorgraduated 90-0-90' with index arm pointeran dwith a graduated edge in inches. Outside is a temperature conversion scale,Troughton & Simms, LONDONscientific-instrument measurement clinometer