Quiz

a horse-drawn tram

The size of a horse's rear end supposedly determines the gauge of a tram. This practice dates back to when horses pulled these things along rails. More precisely, there's a longer chain of events, involving carriages, the Romans, but never mind, it's not the main point. And it's not certain that this applies to trams; I only know about the English railway gauge.
As for the second point... I'm not sure yet.