This particularly rare nickel plated brass gimbal pocket compass was made at the latter part of the 19th century and is housed in a fitted leather case.
Intended for use at sea probably as a personal instrument, it features an ingenious retractable gimbal design, where pulling the frame upward releases two brass pins under the compass bowl, which fall under gravity freeing the transit lock mechanism allowing the dial to pivot on its gemstone bearing, whilst the gimbal ring compensates for the ship's motion.

Pushing the frame back down drops the compass bowl into its recess pushing the two pins in to re-engage the transit lock dial, securing it to prevent wear in transit.

The distinctive black and white aluminium dial pivots on a gemstone bearing, sitting beneath a clean glass crystal and as can be seen from the photos is in very good clean condition.

In good working order this is an unusual design for a pocket compass, measuring 3½" (88 mm) in diameter by 1¼" (32 mm) in depth and weighing just under 490 grams.