Zero Stock- Antique Box Sextant Made by V. & S. Jones Holborn London

SOLD Featured below is a rare early example of genuine pocket sextant or "box sextant" used by explorers for navigation. This piece  was made in the first quarter of 1800’s by the well known scientific instruments maker V.& S. Jones Holborn London.  The Jones are the first company who invented the pocket drum sextant in 1797. 
The one a kind lacquered brass cylindrical body has several fine adjustments: index arm, magnifying  glass, two mirrors, adjustable green and red filters and a silvered vernier scale with very fine markings (0-140). The reading is made through  a sliding peephole. The tangent angles are also engraved nicely on the back of the brass case. A small screw is missing  on the sextant face. Dimensions: 70 mm diameter and 30 mm height.