Hello there: In the US, Tempo markings are figured along the rule that
Tempo 70 means that 7 feet of paper should move across the tracker bar
in one minute, and so on.

I have a Hupfeld roll, made in Europe, that says Tempo 50.  Playing
it at that speed seems too slow, but trying to substitute the metric
system makes the tempo even worse.  Does anyone know about how Tempo
markings from countries other than the US are supposed to be measured?

Randolph Herr