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.