Altitude and Airspeed Handset, Gunnery System B-29 Superfortress

Here is an original WWII-era Altitude and Airspeed Handset as used in the Boeing B-29 Superfortress bomber. This was a module of the B-29's Central Fire Control System, the remote-control gun turret system.  

This critical component was installed at the Navigator's station in the B-29 (see image of the station from the B-29 flight manual. Handset is at the bottom of the photo).  It was his responsibility to ensure that the dials on the handset for altitude, outside air temperature, and airspeed are set to match the actual readings on the altimeter and indicators for temperature and airspeed on the Navigator's instrument panel every ten minutes.  These settings fed into the 5 onboard gunnery computers that determined proper lead and ballistics corrections for each of the 5 gunsights.

The left knob adjusts the barometric altitude which is displayed in the left window. The center knob adjusts the indicated air speed which is displayed on the center dial. The outside air temperature is set by the right knob and is displayed in the right window.  

For as sophisticated this gunnery system was, it is interesting to note that it relied upon a human to read these metrics from instruments and physically input them into the computer system.

Although termed a "handset", at 10 x 8 x 7 inches and 11 lbs, the unit is larger than one might regard a handset, and it was hard-mounted to the aircraft.