Ramsden no 46 : A brass sextant in mahogany box - Please confirm price with client before cataloguing.
93
An important 18th century 15in.(38cm) radius brass sextant, by Jesse Ramsden c. 1773.
Signed on the frame, Ramsden London and numbered 46, bearing the Board of Ordnance mark and Broad Arrow, with rosewood handle. Reading from -5 to 130 degrees on the brass scale, the brass limb with screw vernier to 20 seconds. Horizon mirror with Dollond's patented (1772) lever and clamp adjustment, operated from beneath the telescope. The index glass half-silvered and fitted with a Maskelyne flap. Three red sun shades and a single swivelling horizon shade. In a keystone polished mahogany case, stamped for the Board of Ordnance, and containing a brass sighting tube and a brass inverting telescope with twin cursor lines.
Sold for £27,600 inc. premium

Footnotes

  • Jesse Ramsden (1735-1800) was one of the most important instrument makers of the 18th century, and the inventor of the dividing engine which enabled instrument scales to be manufactured accurately. His brass sextant numbered 33, practically identical to this instrument, was issued to Captain Cook by the Board of Ordnance for his expedition to the South Seas, the Board being also responsible for the office of the Astronomer Royal.

    Ref. National Maritime Museum collection, Greenwich No. NAV1236

Category: Collectibles / Scientific Instruments

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