Sextant, Aircraft Periscopic, MS28011-5
This is a Cold War-era Periscopic Aircraft Sextant and Case, as used by navigators in aircraft of the US Air Force such as B-36 Peacemaker, B-47 Stratojet, B-50 Superfortress, B-52 Stratofortress, and of the US Navy such as the P2V Neptune and others.
The periscopic sextant was used by navigators to fix and track the position of the aircraft in flight, usually by nighttime celestial (star) readings, but also by the position of the sun in daylight. The periscope of the sextant would be inserted through a shutter mount in the top of the cabin to obtain a reading. By viewing the spirit bubble through the eyepiece, the navigator levels the sextant to ensure accurate celestial readings. The sextant also has a timed recording device by which the navigator records readings while in flight.
The sextant is in very good condition, as is the wood case. The lenses are clear and the bubble is intact. We have no way of testing the sextant for correct operation. The case measures ~11 inches by ~8 inches by ~18 inches, which gives one a sense of the size of the instrument, and the entire kit weighs 21 lbs.