Compass, Magnetic Direct Reading, US Navy Mark IX with Plaque
Here is an example of the WWII-era US Navy Aircraft Direct Reading Magnetic Compass Mark IX, as used in the seaplanes PBY Catalina and PBM Mariner Patrol Bombers.
The compass was illuminated electrically via bulb mounted in a small compartment over the compass itself. Inside the same compartment is access to the direction compensating screws, used to calibrate the compass.
This example is in very good condition for its age. The fluid is intact but not full. The compass card rotates freely and its markings are clear. This compass has a plaque noting its use in the PBY Catalina. Measures ~3.3 inches tall by ~5 inches wide and ~5 inches deep, excluding the plaque. The compass rests on the plaque and is not attached.