Theodolite

An "A" frame telescopic theodolite.
Base-Dia. 5.25" (13.3cm) graduated to 360 degs by 30' with two vernier scales 0-30. Fitted with slow-motion screw and clamp. Two spirit levels, one 2.4" (6cm) long mounted E-W, the other 1.6" (4cm) long mounted N-S. A tripod mounting socket with four levelling screws, clamp and slow-motion azimuth screw attached to spindle on underside of base plate.
Compass-Dia. 2.75" (7cm) mounted at centre of base. Fitted with a steel edge bar needle 2.25" (5.7cm) long, with a jewelled pivot cap at centre. Graduated to 8 points (E & W points reversed) quadrantally in degrees. Fitted with a needle lifting mechanism operated by a brass lever at side of bowl.
Vertical arc-Radius 2.5" (7cm) mounted above base on two "A" frame brackets 3.25" (8.3cm) high. Graduated 90-0-90 by 20' with a vernier 15-0-15 (carried on a curved bracket over compass), fitted with a reading microscope. A slow-motion screw and clamp operate on horizontal spindle and one "A" frame.
Telescope-Length 9.25" (23cm) erect with cross wires. O.G. dia 1" (2.5cm). Milled knob at centre for focus at O.G. end. A spirit level 2.5" (6.3cm) long is mounted on upperside of telescope. Carried in two "Y" mounts attached to upper edge of vertical arc.
In fitted wooden box 10.5 x 6.2 x 7.8" (26.7 x 19.9 x 15.6cm) containing 2 eyepieces, one fitted with dark shade and one horn magnifier.

Object Details

ID: NAV1462
Type: Theodolite
Display location: Not on display
Creator: Worthington & Allan
Date made: circa 1830
People: Stokes, John Lort
Credit: National Maritime Museum, Greenwich, London. Caird Fund.
Measurements: 157 x 267 x 198 mm
Parts: Theodolite