Original item: Only one available. This is a Cold War-era Periscopic Aircraft Sextant, as used by navigators in US Air Force aircraft such as the B-36 Peacemaker, B-47 Stratojet, B-50 Superfortress, and B-52 Stratofortress, as well as US Navy aircraft such as the P2V Neptune and others.

The sextant is in excellent condition. The lenses are unfortunately not clear, but the bubble is still present. It was manufactured by Kollsman Instrument Corporation U.S. and it bears the serial number 2368. Some aspects of the Sextant are still in working order, like the timer.

Data Plate reads:

Sextant, Aircraft, Periscopic
MS28011-5
Kollsman Instrument Corporation
U.S.

Navigators used the periscopic sextant to fix and track the position of the aircraft in flight, usually using celestial (star) readings at night, but also the position of the sun during the day. To take a reading, the periscope of the sextant would be inserted through a shutter mount in the top of the cabin. The navigator levels the sextant by looking through the eyepiece at the spirit bubble to ensure accurate celestial readings. The sextant also includes a timed recording device, which allows the navigator to record readings while in flight.

A periscope includes two mirrors or reflecting prisms to change the direction of the light coming from the scene observed: the first deflects it down through a vertical tube, the second diverts it horizontally so that the scene can be viewed conveniently. Frequently there is a telescopic optical system that provides magnification, gives as wide an arc of vision as possible, and includes a crossline or reticle pattern to establish the line of sight to the object under observation. There may also be devices for estimating the range and course of the target in military applications and for photographing through the periscope.