Pilot's and Flight Engineer's Notes Halifax III & IV, AP1719C&G-PN MiG-21 aka Barr & Stroud model

aka Barr & Stroud model GJ3

It has the original crown symbol of the Air Ministry on the back

The knob rotates the face of the instrument to correct the scale

Here is a 1940-50s-era dual engine Fuel Pressure Indicator made by Edison PN 34955

that illustrated speedometer does show a tripmeter so it only goes to assume that it had to have a reset knob like the one in our example

Pilot's and Flight Engineer's Notes Halifax III & IV, AP1719C&G-PN MiG-21 aka Barr & Stroud modelThis is a post WWII Air Data Publications reprint of the October 1944 Air Ministry Publication. Includes checklist, airplane handling, emergencies, foldouts of cockpit pictures and instrument panel. This ~50 page black and white manual is in very good condition. Measures 7. 5 inches long and 5 inches wide.