Noun
An instrument used, especially in trigonometrical surveying, for the accurate measurement of horizontal angles, and also usually of vertical angles. It is variously constructed.
Source: Webster's dictionarySince the violet rays through the objective of the theodolite telescope have a shorter focal length than the red rays, it is evident why the eye-piece must be displaced in order to see plainly the lines in the different colors. Joseph von Fraunhofer
Additionally a compass can only measure the azimuth to a precision of a half a degree. citation A theodolite can be considerably more accurate if used correctly, but it is also considerably more difficult to use correctly. Source: Internet
Directional control passed from one theodolite to the one next to the missile. Source: Internet
Surveying main Civil engineering student using a theodolite Surveying is the process by which a surveyor measures certain dimensions that occur on or near the surface of the Earth. Source: Internet
The missile then oriented to north by an operator using a horizontal laying theodolite aimed at a window in the guidance section of the missile. Source: Internet
There is no inherent way to align a theodolite with North and so the scale has to be calibrated using astronomical observation, usually the position of the Sun. Source: Internet