Altimeter, Sensitive, Type C-12, 50,000 ft, US Army Air Force WWII JU-88 can interpret them by rotating

can interpret them by rotating the card to match the arm position being observed

the tachometer is in the middle of the second column of instruments from the right) and MIL MI-4 (see cockpit photo

With a serial # AC42-670

but utilizes an electro-magnetic compensation system

As an offshoot of this equipment Ryan have also developed a helicopter hovering aid (AN/APN-97) which presumably uses Doppler signals to tell the pilot whether or not his machine is stationary above ground or sea

Altimeter, Sensitive, Type C-12, 50,000 ft, US Army Air Force WWII JU-88 can interpret them by rotatingHere is an early WWII era Sensitive Altimeter, Air Corps US Army Type C 12, made by Conn. 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. It has a serial number prefix AF 43, evidence of a manufacturing year 1943.