Tachometer, Chronometric, Type C-7, WWII, Air Corps US Army Bf-109 while the right dial selected

while the right dial selected the number of bombs to be released at a time

Once the aircraft reaches 5000 Meters

There is a "0" above an "A" at center position flanked by a "L" and a "E" to the left and right of the scale

by showing increments of quarter fractions from 0 degrees (Up) to fully extended 45 degrees (Down)

Here is an Aircraft Inspection and Maintenance Guide for the Boeing B-29 Superfortress bomber of the US Air Force dated 1948

Tachometer, Chronometric, Type C-7, WWII, Air Corps US Army Bf-109 while the right dial selectedHere is an example of the WWII era Chronometric (i. e. mechanical) Tachometer, Type 7, as used by early single engine aircraft of the Air Corps US Army. According to the US Army Air Force Maintenance Interchangeability Chart dated Feb 1945, the C 11 tachometer was used in fighters P 40 Warhawk (E N), early versions of the P 47 Thunderbolt, and P 51 Mustang, dive bombers A 35 Vengeance and A 36 Apache, and transports UC 61 and UC 64A. This tachometer