Epact Scientific Instruments of Medieval and Renaissance Europe

The magnetic compass is set within the four leaves of a compass hinge for two large and elaborately shaped and pierced compass legs, curved and terminating in shaped points. One leg is fixed by rivets to the plate, the other pivots around the circle, with a pointer reading against the three scales. Towards the ends of both legs are solid sights above and feet underneath. Set on the moving leg, on a hinged mount, are the two uprights for a gunner's sight, level and clinometer, which can be secured in the upright position by two screws, or folded down, or removed by withdrawing the pin of the hinge. The uprights are joined above by a shaped and pierced brass arch, into which fits the vertical screw of the gunner's sight. The sight is moved in slots in the uprights, against a scale 0 to 45, divided to 5, subdivided to 1, numbered by 5. On the other upright is a vertical hinge for a quadrant clinometer; the quadrant can fold across the sight to allow it to be folded down, but in use is set at right angles to it. It is decorated and initialled 'BL', and has a brass plumb-line moving across a degree scale 45 to 0 to 45, divided to 5, subdivided to 1, numbered by 5. When the sight is screwed completely down, it forms the near sight when using the sights on the legs. The feet beneath the legs and one beneath the circular plate are contoured for sitting on a gun.