As of a few weeks ago, I have held a Curta pepper-mill mechanical calculator in my hands. And heard it, and felt it, calculate. Marvellous! I don’t suppose I’ll ever own one.
Here’s a quick demo:
And here’s how the mechanism works:
Anyone know a good way to compute Pi on such a machine? I don’t mean 355/113…
… I’m thinking there must be some converging series or iterative calculation which doesn’t need much state. Maybe
Here’s a poster showing all the parts:
(Masses of background and good links on that site.)
Oh, and it was popular with rally drivers too - or, perhaps, their co-drivers:
The popularity of the Curta among rally drivers was due to two salient facts: Herzstark’s invention was irrefutably accurate and, at the same time, tough enough to take the knocks of high-speed racing. So much so, that rally teams continued using their Curtas to measure times, speeds and distances into the 1980s, despite the emergence of modern pocket calculators. Racing drivers who swore by their cylindrical devices earned the memorable nickname of “Curta-crankers”.