Aircraft Instruments by Emanuel Stieri 1943 C-121 Above the center axis is

Above the center axis is a window to display barometric pressure in millibar

For the earth

Measures 4 inches diameter and ~11 inches deep

The instrument measure approximately 4 inches wide and 10 inches tall

This is a pair of 1940-50's vintage dual engine Oil Pressure Gages

Aircraft Instruments by Emanuel Stieri 1943 C-121 Above the center axis isHere is a hardback bound pocket reference for Aircraft Instruments by Emanuel Stieri published in 1943. With over 200 black and white illustrations, Stieri discusses most of the instruments used in aircraft of that era, including tachometers, airspeed indicators, gyro horizons, compasses, drift meters, quantity and temperature indicators, and more. The author describes the instruments, how they function, and the most common servicing procedures.