拍品 167
167
A Ramsden-pattern ebony and brass miniature surveying octant, with ivory scale divided 100-0, pin-hole sights, twin-mirrors, and three shades, the index arm with ivory vernier scale, tangent-screw and clamp, and screw-mounted handle -- 4½in.(11.5cm.)wide, late 18th/early 19th century

细节
A Ramsden-pattern ebony and brass miniature surveying octant, with ivory scale divided 100-0, pin-hole sights, twin-mirrors, and three shades, the index arm with ivory vernier scale, tangent-screw and clamp, and screw-mounted handle -- 4½in.(11.5cm.)wide, late 18th/early 19th century