Dated: 1736
Fig. 45 (right).
By the second quarter of the 18th century the format of an offset 45° arc and vertical sliding sight was evidently well-established for the gunner's combined level and sight. This instrument adds some refinements by using two screw threads, one to adjust the position of the sight and the other to move the upright across the foot. In addition, the reverse of the instrument carries two square brackets which could be used to hold a vertical device, perhaps a perpendicular to mark the sight line on a barrel.
Height: 105 mm
Inventory no. 51,507