Octant by R. L. Shaw, New York, circa 1840

octant

Ebony octant; stamped on rectangular ivory maker's plate "R L Shaw New York"; ivory arc very neatly graduated -2 to +99 divided to 20'; vernier right to left 20 0; double peep w/ rotating shutter on back; feet, one broken off; 3 red index shades (possibly replacements); index mirror, one retaining tab top center & two bottom at sides, perpendicularity adjustment flange at back; index arm has ctr. rib screwed on; index error adjustment knob on back; tangent screw on back of arm; lower edge of limb grooved to accommodate ridge on tangent screw fitting. Provenance: Harris D. Rush (b. 1879); Harris C. Rush (b. ca. 1850). Radius, pivot to centerline of scale 10 5/16"; radius frame 11 11/16"; chord of arc 10 3/8"; horizon glass 7/8" x 1 1/16". Dated ca. 1840 [Ref: Willem Morzer Bruyns, July 2006].