Gyrosyn Compass C-2A Sperry Master Indicator 653894-6B C-119 Boxcar USAF

This is a Gyrosyn Compass Master Indicator Type C-2A made by Sperry part number 653894-6B. The Master Indicator was part of a 5 module system combining the functions of a directional indicator and a magnetic compass, introduced in the late 1940's. See the diagram of the system with an explation of its function in the photo gallery, including a diagram of this specific indicator. An illustration of its position on an instrument panel is in the photos - from the US Air Forces C-119 Flying Boxcar flight manual dated 1950. Measures 3.25in diameter and ~8in deep. It is in nice condition given its age. The knob rotates the directional indicator card when depressed and turned.  The dial markings are clear and the glass and case are intact.