Octant and case, English, circa 1780

octant and case

INSTRUMENTS - OCTANTS
England
circa 1780
radius 17-1/8 in.; case 18-5/8 x 17-3/8 x 3-15/16 x 3-15/16 x step 2-3/8 in.

Octant, frame ebony, unmarked ivory nameplate, limb ebony, scale ivory graduated -5 deg. to 95 deg. by 1 deg. subdivided to 20', left end marked "166". Flat brass index arm, ivory vernier. Adjustable index mirror w/3 shades. Horizon glass w/adjustment & shades from index mirror. Sight vane w/dbl. peep & swinging disc. Back sight w/single peep. Horizon glass removable to back horizon, w/adjustment. Ivory note plate on back of frame, wooden pencil w/turned ivory finial screws into pencil hole in brace. 4 brass feet (2 used as horizon glass tighteners), a 5th brass leg missing from back at top. In step keystone mahogany box, 2 leather strap slots in bottom of case. Case 18 5/8" x 17 3/8" x 3 15/16" x 3 15/16" x step 2 3/8". English manufacture, dated ca 1780.

1974.1053