An early 19th-Century brass and ebony octant, signed on the makers ivory plaque H. DUREN NEW YORK, with double 'pin-hole' sight and slide, six shades and mirrors, the brass index arm with framed ivory vernier scale and clamp, the inset ivory arc engraved with scale divided 0°o-100°o on three brass pillar feet in stepped mahogany case with trade label for F.W. LINCOLN JR & Co Nautical Instrument Makers No. 126 Commercial St., Boston. over other labels - 13in. (33cm.) wide.