細節
A 19TH CENTURY 8¾in. RADIUS VERNIER OCTANT BY CRICHTON & SONS
with double 'T' ebony frame, inset ivory scale divided 2½°- 0°- 105°, vernier with clamp and fine screw adjustment, brass index arm, signed on ivory on the cross bar Crichton & Son, London, sighting tube, seven shades, two mirrors, mahogany handle and brass pin feet. Contained within fitted mahogany keystone box with accessories, trade label for T.J. Williams, Cardiff, lock and securing hooks -- 5 x 11½ x 12in. (12.7 x 29.2 x 30.5cm.)
See illustration