A theodolite 's an instrument for measuring both horizontal and vertical angles, as used in triangulation networks. It's a key tool in surveying and engineering work, particularly on inaccessible ground, but theodolites have been adapted for other specialized purposes in fields like meteorology and rocket launch technology. A modern theodolite consists of a movable telescope mounted within two perpendicular axes—the horizontal or trunnion axis, and the vertical axis. When the telescope's p… (More on Theodolite)