theodolite

n. small tripod-mounted telescope used for measuring horizontal and vertical angles

A theodolite is an instrument for measuring both horizontal and vertical angles, as used in triangulation networks. It is a key tool in surveying and engineering work, but theodolites have been adapted for other specialized purposes in fields like meteorology and rocket launch technology. A modern theodolite consists of a telescope mounted movably within two perpendicular axes, the horizontal or trunnion axis, and the vertical axis. When the telescope is pointed at a desired object, the angle of each of these axes can be measured with great precision, typically on the scale of arcseconds.
See more at Wikipedia.org...

Noun
1. a surveying instrument for measuring horizontal and vertical angles, consisting of a small telescope mounted on a tripod
(synonym) transit
(hypernym) surveying instrument, surveyor's instrument
(hyponym) tachymeter, tacheometer
(part-meronym) alidade, alidad

n. theodolite, an instrument for measuring horizontal and vertical angles consisting of a small telescope

(n.)
An instrument used, especially in trigonometrical surveying, for the accurate measurement of horizontal angles, and also usually of vertical angles. It is variously constructed.