Compass, Direct Reading Magnetic, US Navy Mark X

This WWII-era Direct Reading Magnetic Compass Mark X, Kollsman 398-01-2702 was made for aircraft of the US Navy such as the seaplane JRF-5 Grumman Goose.

The interesting aspect of the design of this compass is that the directional mechanism lies horizontally within the rear chamber, and displays the direction on a vertically-mounted compass card.  In addition, the desired course heading can be selected by rotating the knob at the bottom center of the dial, which turns the double-arrow pointer clockwise or counter-clockwise.  The single pointer would indicate true magnetic north.  There are adjustment screws for E-W and N-S for calibration alongside the course setting knob.  See Kollsman diagram in photo gallery.

This example is in reasonable cosmetic condition but does not fully function. The single pointer and course setting arrow rotate, but the fluid in the rear chamber is absent and there is a slight internal rattle. The lamp is present but its ability to illuminate is unknown.