Altimeter, Sensitive, Type C-12, 50,000 ft, US Army Air Force WWII Mosquito Sweeting’s book "Combat Flying Equipment":

Sweeting’s book "Combat Flying Equipment":

Must have been a high pressure application judging from its construction (number of screws and thickness of lens)

The main dial measures time

which cross references to those used in RAF aircraft

Altimeter, Sensitive, Type C-12, 50,000 ft, US Army Air Force WWII Mosquito Sweeting’s book "Combat Flying Equipment":Here is an early WWII era Sensitive Altimeter, Air Corps US Army Type C 12, made by Conn, part number 80000. The C 12 Altimeter was used across all aircraft of the Air Corps US Army, including heavy bombers B 17 and B 24, medium bombers, B 25 and B 26, Fighters P 38, P 39, P 40, P 47, and P 51, and transports C 46 and C 47, according to the Maintenance Interchangeability Chart dated Dec 1943. The knob is used to adjust the altimeter to the barometric