Double framed sextant

Troughton and Simms1810 – 1860

Australian National Maritime Museum

Australian National Maritime Museum
Sydney, Australia

This copper alloy double framed sextant is attributed to Troughton and Simms of London, England. Sextants were used to obtain the angles or height from the horizon of a celestial body such as stars, planets, the moon or the sun. This information could then be used to calculate a vessel's latitude and, aided by a chronometer and mathematical tables, its longitude.

The construction technique used for this sextant produced a very rigid, robust and accurate instrument, and was first developed by Troughton and Simms in the early 1800s and remained popular until the development of lighter sextants in the 1850s.

This sextant is complete with silver arc scale, filters and additional telescopes, in a fitted wooden case.


  • Title: Double framed sextant
  • Creator: Troughton and Simms
  • Date: 1810 – 1860
  • Location: London
  • Type: Sextant
  • Significance: This is a fine and rare example of a sextant which represents the high level of technological development achieved in the design and manufacture of navigational instruments in the early 19th century. Sextants were essential for the safe navigation of a vessel out of sight of land and were used for ocean voyaging.
  • See institution's online collections: http://www.anmm.gov.au/collections
  • Medium: Copper alloy, wood, glass
  • Dimensions: 109 x 260 x 300 mm, 1.46 kg
  • Credit line: ANMM Collection

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