Rare and 100% original Bomber Altitude Correction Computer used for flying by the bomber navigator. From 1944, this is an AN-5837-1 Altitude Correction Computer made by the Cruver Manufacturing Co. Great original example in functional condition, with the original box included. This specific model was made in 1944. The AN in the model number usually means Army/Navy, so I believe this is a US military aviation item. 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. Rare and nice addition to your US WW2 collection!