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A 19th Century English Theodolite by J. Davis and Son, Derby. Made of lacquered brass, standing 33 cm (13 inch) high on its 4-screw leveling base. The telescope is 35.5 cm (14 inch) long with a 2.5 cm (1 inch) diameter objective, rack and pinion focusing and draw-tube movement to the eyepiece. 3 bubble level mounted in 3D positions. Both vertical and horizontal circles are 13.5 cm (5 ½ inch) diameter with tangent screw controls. The circles graduated on silver with opposing venires and eyepiece readers. The vertical 6 spoke circle is mounted on a 23 cm (6 ½ inch) tall support attached to the top plate together with a 7 cm (2 ¾ inch) compass signed by the maker. The Theodolite is complete and in very good condition. Davis Derby was a family business established in Leeds in 1779 by Gabriel Davis as a manufacturer of optical, surveying and mathematical instruments. In 1833, Gabriel’s nephew, John Davis (born 1810) moved to Derby and manufactured a variety of surveying instruments such as Levels, Theodolites, Surveying and Miner's dials. Henry, his eldest son, was trained as a civil engineer and upon the death of John Davis in 1873, was appointed to run the business and named the company as ‘John Davis & Son (Derby)’. The original dove tailed mahogany case with brass carry handle, lock and key is included. An original label pasted to the inside lid indicates the instrument was repaired and adjusted by T.B. Winter in Newcastle on October 1914. The label reads, ‘T.B. Winter, Manufacturer of Mathematical, Nautical, Philosophical, and Optical Instruments, 21 Grey Street, Newcastle on Tyne, Spectacles to suit all sights.’ The case is in excellent usable condition. |
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