Bausch and Lomb
Aircraft Sextant AN5854-1 and Carrying Case
This is a WWII/Post-War-era Aircraft Sextant AN5854-1, made by Bausch and Lomb, with Carrying Case and suspension hook (for hanging the sextant below the navigator's dome). This sextant was used by air navigators of the US Army Air Force, US Navy, and US Air Force. This sextant is stamped USN.
The sextant appears to be intact. The knob rotates to position the prism. The rheostat knob rotates. The bubble knob rotates but the bubble is not present. The horizon slide knob is very stiff but still slides. The sun filter dial does not rotate. Maintenance by a knowledgeable technician is suggested. Included is a small box containing a replacement lamp and lens cleaning tissues. Absent is the separate battery module. The rubber eyepiece is has deteriorated with age. This sextant is sold for display or as core for parts.
Here is some interesting information from Deborah Warner's Celestial Navigation Aloft: Aeronautical Sextants in the US:
Bausch & Lomb's last air sextant was their model #61-90-04 (Army designation AN 5854-1 and Navy designation ES.S.C. 88-S-375). The firm donated an example to the Smithsonian in 1948, noting proudly that it had been 'patented and manufactured by them' . Representatives from several aviation training commands conducted extensive tests with an instrument of this sort in September 1943 and recommended that it be 'considered for adoption as the standard sextant for the Army Air Forces'. It was rugged and compact, and easy to balance, and gave less trouble than any other sextant. It had an electric light for standard illumination and radium for low-intensity illumination. It also had a 15-shot median device that was simple and self-explanatory, and that offered 'a fool-proof visual average, which is easily understandable to the navigator' .