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"An altazimuth theodolite of an improved pattern now used on the Ordnance Survey. The horizontal circle of 14 inches diameter is read by three micrometer microscopes; the vertical circle has a diameter of 12 inches, and is read by two microscopes." — Encyclopedia Britannica, 1893

Altazimuth Theodolite

"An altazimuth theodolite of an improved pattern now used on the Ordnance Survey. The horizontal circle…

An instrument, variously constructed, used especially in surveying.

Theodolite

An instrument, variously constructed, used especially in surveying.

"An instrument for the measurement of horizontal angles, consisting essentially of a telescope mounted so as to move on a pivot both horizontal and verticaly." — Williams, 1889

Theodolite

"An instrument for the measurement of horizontal angles, consisting essentially of a telescope mounted…

"An instrument much employed in land-surveying for the measurement of angles horizontal and verticle." — Chambers, 1881

Theodolite

"An instrument much employed in land-surveying for the measurement of angles horizontal and verticle."…

"The instrument is supported on a strong tripod, fitted with levelling screws; to this tripod is fixed the azimuth circle and a long vertical steel axis. Fitting on this axis is a hollow axis which carries on its uper end a short transverse horizontal axis. This latter carries the telescope, which, supported at the center of its length, is free to rotate in a vertical plane. The telescope is thus mounted excentrically with respect to the vertical axis around which it revolves." — Encyclopedia Britannica, 1893

Zenith Telescope

"The instrument is supported on a strong tripod, fitted with levelling screws; to this tripod is fixed…