An amazing handheld rotary calculator designed and built by Curt Herzstark.
When I was working with a land survey crew in the late 1960's, we used this gadget to calculate lengths, areas, and positions with absurd accuracy.
The PocketCalculator? had not yet arrived, and the SlideRule was only good to a couple of significant digits. The Curta (which resembled a small mechanical pencil sharpener) was good to 10 or 11 significant digits.
Some references:
-- GarryHamilton
Whoa! That looks so cool! It literally lets you grind out a calculation! I bet they are high-priced collectors items these days.
Current pricing on eBay starts around $500.00 (US)
Here's a cool site: http://www.vcalc.net/curta_simulator_en.htm
The CurtaCalculator had a small but high-profile part in WilliamGibson's book PatternRecognition. It's part of Gibson's themes of authenticity and mass production.
See also MathWithoutaCalculator