Object photography

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Object description

  • John Dupee (American)
  • Octant, or hadley's quadrant, 1755
  • Mahogany, ivory, boxwood
  • Boston, Massachusetts
  • H: 21 1/2 in, W: 18 1/2 in, D: 3 in (H: 54.6 cm, W: 47.0 cm, D: 7.6 cm)
  • Gift of Anna F. Lovett, 1908
  • M1034.A


An octant, or Hadley’s quadrant. Frame mahogany, radius 20". Name plate ivory marked "Made by John Dupee 1755 For Patreck Montgomerie". Limb boxwood, two pieces, joined at 45 degree point. Scale engraved on limb graduated 0 degrees to 90 degrees by 1 degree subdivided to 20', diagonals from-20' to 1' with zenith numbering. Flat mahogany index arm inlaid ivory "line of faith " over the scale. Brass arm stop. Horizon glass with leveer adjustment and shades from index mirror. Sight vane double peep with pivoted cove. Back sight with single peep. Back horizon with lever adjustment. Step pine box, painted black.