Brass framed surveyor's quintant.
Surveyor's quintant invented by George Beck and made by M. Dawson, Plymouth, about 1780. Polished brass frame, a detached wooden handle. Signed on the index arm: M,, Dawson fecit | Plymo Dock No 6. Marked on the index arm: G. Beck Invt. Polished brass scale from -10° to 205° every 30', measuring to 193°. Brass vernier to 1', zero at the centre. The double-ended tangent screw and the clamping screw are on the back of the index arm. No shades. Two index glasses, adjustment by screws; adjustment of the horizon glass by two levers and a milled clamping screw. A partly silvered sight vane with a peephole is fixed next to the index glass; a second sight vane on a swivelling arm is fitted on the centre strut.
