It was the section of the North Midland Railway from Derby to Ambergate which provided the springboard for a scheme that took shape in the early part of 1845 for a route through the Peak to Manchester.

Ersatzgas, Ersatzpfennige. Ersatz has become a brave word in Germany. As a substantive it means War Reparations. As part of compounded words it means substitute.

Can it be Friday already?

If A and B are sets, their direct product is the set of ordered pairs (a,b) with a in A and b in B.