I enjoyed reading about the lost art of safecracking in this illustrated lecture by Tim Hunkin.
The nobel prize winning physicist, Richard Feynman, became very interested in combination locks while working on the atomic bomb in Los Alomos during the second world war. Los Alamos was in the middle of the desert, so there wasn't much to do when he wasn't working, and safe cracking became a sort of hobby. As the project was all top secret, every office had combination locks on its filing cabinets. Feynman first discovered, playing with the locks on his own filing cabinet, that the numbers did not have to be that precise, each one could be up to two digits either side of the true number and the lock would still open. This enormously reduced the number of possible combinations (from 1,000,000 down to 8,000). With practice he found he could try 400 different combinations in half an hour, so trying every single combination it would take on average 4 hours to open the lock. A modern version of this, advertised on the internet, is a motorised German device that turns the dial, trying every combination in turn, for use by locksmiths trying to get into a safe whoes combination has been lost.
Link (Via Sensible Erection)
