A classic mid-18th C. "Hadley Octant", signed on the inlaid ivory nameplate "Gregory, London." Known in common usage as a reflecting quadrant, or simply "quadrant," this instrument has a single piece wooden "crab claw" index arm and a diagonally engraved boxwood scale. The ivory "line of faith" from which the reading was taken is clearly visible across the scale. (Private Collection. Ex. West Sea Co.)