12:24 PM
The Curta handheld mechanical calculator may be the coolest thing I've stumbled across online in quite a while:

The Curtas were marvels of mechanical miniaturization which were introduced by Contina Ltd. in 1948. They were designed by Curt Herzstark while he was a prisoner in a concentration camp. Herzstark worked out the basic design in his head and polished it on paper when he was released in 1945. Herzstack's design was based on the stepped drum mechanism but with a brilliant adaptation that allowed a remarkably simple and compact design. The small hand held devices could be used to perform the four basic functions and the later manuals included algorithms for cubes and square roots. ... The machines were cylindrical with numbers input on sliding levers around the body. Above each lever was a window that showed the number entered in that position. Below the number levers was a base/grip used to hold the machine and on the top there was a crank called the "operating handle". Also found on the top were two more number registers (the revolution counter and the result dial), decimal markers and a clearing lever.

If it isn't clear how you operated the Curta from that description, here's an HTML version of the original Curta manual. Once you think you've got it all figured out, try it for yourself with a Flash-driven Curta simulator.

From another Curta fan with a steady hand, a brave soul, and a digital camera, a look inside a Curta. If you want an even more detailed view of the Curta's innards, here's a desktop ready exploded view (also available as a poster, courtesy of the creator's own Curta dissection.)

Further reading on the Curta: the history of the device and an interview with its creator, and an article from a 1976 issue of Rallye Magazine describing how Curtas were used by rally drivers.

I want one. There are a few Curtas for sale on eBay, but unfortunately I don't have multiple hundreds of dollars to spare. Sigh.