Double-Frame Navigation Sextant By Troughton

Double-Frame Navigation Sextant By Troughton

double Frame Sextant by the inventor "Troughton, London" circa 1800. On
the vertical limb above the scale is the engraved serial number "1005" . The large arc is calibrated up to 150 degrees and the unique vernier magnifier (seen as a brass disc). Troughton invented the double or "pillar frame" sextant in 1788, so named because it consisted of 2 thin sheet frames of brass braced together with brass pillars to form a lightweight and rigid platform on which to construct a hand-held instrument for taking celestial observations. While the double frame proved to be an effective 18th C. concept -- one which gave Troughton great notoriety as a respected instrument maker -- the complexity and cost of producing such sextants gave way to more simplified designs by the mid 1800's
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Double-Frame Navigation Sextant By Troughton Double-Frame Navigation Sextant By Troughton