A RARE 16½IN. GEODETIC THEODOLITE OR PORTABLE ALTAZIMUTH REPEATING CIRCLE BY TROUGHTON & SIMMS, LONDON, 1829
heavily constructed in lacquered brass, signed and dated on the solid bedplate as per title, silvered meridian scale divided 0-360° with micrometer microscopes, tapering pillars with central bracing pivot supporting a pair of braced six-spoke circles, the right inset with silvered scale divided in four quadrants of 0-90°, with micrometer microscopes and a 2in. telescope with adjustable aperture lens cap, the whole set on adjustable threaded feet -- 31½ x 23 x 18in. (80 x 58.5 x 45.7cm.)

Similar examples are housed in the collections of the Museum Victoria in Australia (1836), acquisition number ST 022216; and The Royal Museum of Scotland in Edinburgh (1806)

Literature: Bennett, J.A. The Divided Circle, Phaidon, Oxford, 1987, p.165 & 196

Appears to retain much of its original finish and is in generally very good overall condition for age and no case; there are some missing components including the telescope eyepiece; one of the retaining screws securing the left transit limb, and the eyepiece for the left-sited base-plate microscope. The telescope main lens is in good condition as is the transit limb lens. The weight is approx. 20kg.