Compass, Direction Indicator, Kollsman Type 488C-01-615 Poly-Plane Compensator
This appears to be a 1930's-era Compass and Directional Indicator, made by Kollsman. We've not seen one until this specimen was found, have failed to locate any documentation on it, and therefore can only share what we can physically examine.
It is a large instrument, 5.5 inches diameter by ~4.25 inches tall and 4lbs in weight. It is comprised of a liquid-filled compass, which indicates with the thin inner pointer, and a larger direction indicator pointer, which is to be set by rotating the knob at the center South position. It would have been attached to a 12 volt power source, and was illuminated by turning the two small bulb/knobs on either side of the center knob. It has a calibration mechanism, the "Polyplane Compensator" to correct for compass deviation. This navigational instrument was likely mounted on a pedestal or shelf either in the cockpit or at a navigator's station.
This specimen is clearly experienced, but an interesting artifact nonetheless. It appears to have been opened for repair judging by the screw witness marks, and the pointers do not operate. However, liquid can be heard within the reservoir below the dial, and there are no apparent leaks.
A very cool, and curious, artifact indeed.