Another Mechanical Calculator

This video demonstrates the Original Odhner mechanical calculator.

http://www.youtube.com/watch?v=Bz8_tNDUDog

It looks like a miniature typewriter, and it seems to operate in the same manner as the Curta mechanical calculator:  switches allow you to “input” numbers into the machine, and then turning a crank performs addition or subtraction.

The video demonstrates some basic operations of the Odhner, and it includes  a nice (if lengthy) computation of the square root of 2 that involves a few arithmetic tricks.