Gunner's quadrant and perpendicular, c 1780.

Gunner's quadrant and perpendicular by George Adams the Younger, c.1780. This instrument was designed primarily to ensure that a cannon or mortar was elevated to the required angle. Quadrants were also used for navigational purposes to determine the altitude between some heavenly body and the horizon. George Adams (1750-1795), was instrument maker to George III, as his father was before him.