A fine and impressive 8-inch Troughton & Simms transit theodolite, English, late 19th century,
signed Troughton & Simms, London, the telescope with cover to the objective and rack and pinion focusing, vertical 8-inch silver scale with three micrometer magnifiers and bubble level enclosed in glass case, supported by a large double bracket above horizontal circle of degrees, two micrometer magnifiers and tangential screw adjustment, the whole raised on tripod base with three levelling screws, in two mahogany cases with large brass carrying handles and the door on one applied with the trade label of Bardelli & Co of Torrino 19.5in(50cm) high
Sold for
£7,200
inc. premium
Footnotes
- The case door interior is applied with a label written "Theodolite No. 2" indicating this was one of a pair of Troughton & Simms large size theodolites used for a major surveying project such as mapping a country.
By the end of the 19th century transit theodolites were being produced in a variety of sizes. The instrument maker Stanley is quoted as saying:
A 5-inch or 6-inch theodolite is the largest size that may be carried comfortably in a single case; and no great advantage is gained by having an instrument beyond that size if the work is that of the ordinary survey on town or country surveys. The vernier of 4-inch and 5-inch instruments read sharply to single minutes of arc, which is as nearly as can be plotted with any degree of certainty with an ordinary protractor reading by vernier also to to minutes only; 6-inch instruments read to 30 but generally 20 seconds.
Category: Collectibles / Scientific Instruments
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