The tachymeter-dial (FireFox autocorrects to “o”…) is marked Base 1000 mètres and in the dial-centre Base 100 mètres. F.i., 15" into the 1st (red) min. = 240 kmh. Was there any thing short of a strong wind that travelled 240 kmh in 1929? 1min 15" (360° wraparound) is 48 kmh. I do guess they would count more than meter-fabrication ;-) and it can measure any time-number relation, but my maths courses are many wraparounds back.
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