Mechanical computers

At 05:17 PM 1/13/99 -0800, Uncle Roger wrote: Which is, incidentally, still on display at The Computer Museum in Boston. It hasn't been run for a while, though, so it probably would need considerable tuning to work. If the subject is mechanical computers in general, one of the most prolific inventors thereof was Prof. Derrick Lehmer (1905-1991) who was on the faculty at UC Berkeley for about 50 years. His hobby was devising different kinds of mechanical sieve computers to solve linear congruence problems like finding primes. At The Computer Museum History Center at Moffet Field in Mountain View CA (the historical spin-off of the Boston museum) we have at least four of his sieve computers, made of principal components as follows: 1. Cardboard sheets with holes, operated by knitting needles 2. Bicycle chains of various lengths with screw stops 3. Heavy toothed gears, toothpicks, and a car headlight 4. 35mm film and wooden mallets The guy was a regular Rube Goldberg, but they all worked! -- Len Shustek