Brass Box "Pocket" Sextant ca late 19th Century

This is an original brass Box Sextant, or "Pocket" Sextant.  At 3 inches in diameter and 1.5 inches when closed, it could easily fit in the pocket of a mariner for determining position at sea or for determining horizontal positions on land.  Box sextants have been around since the early 1800's.  We speculate this example was made in the late 19th century. 

The protective outer case unscrews from the mechanism platform and screws back on to it's opposite side, becoming a convenient handle fitting into the palm of the hand. 

To take a reading, one peers through the circular viewfinder at the celestial body or other target of interest and adjusts the large control knob to obtain the desired view. This action has also moved the arm along the silver scale. The arm-mounted magnifier can then be used to read the finely engraved degree markings on the scale to obtain the position of the target.

There are two shades, red and green, mounted on small levers that can be placed in the line of the view or out of the way by opening a small rear hatch and adjusting the side levers. Both would be used to view the sun directly.  During our inspection of the internal mechanism, it appears that one of the shade levers may have been repaired at some point.

There are many reproductions in the market.  Upon reviewing the details on the website of sextant expert and author Bill Morris regarding box sextants, we believe this example is NOT at reproduction based upon its detailed workmanship and, in particular, the fine engraving on the silver scale and arm. There are no markings of any manufacturer to be found on this example.