Can't help with .22 but I have a Markham Pacific in 0.18, allegedly from 1885 onwards. As well as the calibration it is remarkable for the lack of metal content. It's in marked contrast to my Giffard from the same period.
The only ancient continental linear measurement I can recall is a pipee - the distance a Frenchman would walk while smoking a pipe although it could just as accurately and meaningfully be the time elapsed. Hardly helpful, I know.
ATB. Mick
When guns are outlawed only outlaws will have guns .