Rare and 100% original Bomber Altitude Correction Computer used for flying by the bomber navigator. Great original example in functional condition, with the original box included. This specific model was made in 1943. From 1943, this is an AN-5837-1 Altitude Correction Computer made by the Felsenthal and Sons.The AN in the model number usually means Army/Navy, so I believe this is a US military aviation item. The one you will receive is identical and UNOPENED in the original box, see pictures 6,7 etc for the actual boxed one.
The airfield elevation is dialed into the slide rule opposite the airfield observed pressure.Using the second cursor, the density altitude is read opposite the observed mean dry bulb temperature.The slide rule is made of plastic and is 8 inches in diameter.