In his letter in your March issue, I see that Geoffrey Richardson mentions that he saw a Connaught engine being tested at Send using a chronometric rev counter, as fitted to the cars.
This is not surprising, as when an engine was installed in the test house, it was common practice for the car’s rev counter to be included. This was done to enable its accuracy to be checked against the calibrated master instruments in the test house.
Any error was recorded, and a sticker applied to the face of the instrument. The car rev counters were never used to measure engine speeds on the dynamometer.
RM Oliver, Yarcombe, Devon