Theodolite
A theodolite is a tool for measuring angles between two places (or points) from one place. They are usually associated with surveying. They are often mounted on a special kind of tripod.[1][2]
They are usually a telescope on a mount that can move horizontally (left and right) and vertically (up and down). The mount has a scale where the readings are taken, usually in degrees for older models and arc minutes or arc seconds for newer models. The telescope normally has a crosshair to make it easy to align it to the points to be surveyed. The theodolite was the first tool that could do vertical and horizontal measurements in the same device.
Most modern theodolites are electronic and the readings are read from a digital display.
A transit is a kind of theodolite that can do a whole circle vertically and horizontally.
Theodolite Media
A direct-readout theodolite, manufactured in the Soviet Union in 1958 and used for topographic surveying
The axes and circles of a theodolite
Diagram of an optical readout theodolite
A typical modern electronic theodolite: Nikon DTM-520
Jesse Ramsden's Great Theodolite of 1787
A theodolite of 1851, showing the open construction, and the altitude and azimuth scales which are read directly
A theodolite of the transit type with six-inch circles, manufactured in Britain c. 1910 by Troughton & Simms
Wild T2 theodolite originally designed by Heinrich Wild in 1919
Surveying Theodolite
