Leonardo’s adding machine?
- The story of a controversial replica calculating machine based on a sketch in a ‘misplaced’ manuscript by Leonardo is told on a page devoted to the sketch in the Madrid Codex
- The Calculating Machines Web site has a lot of information on the operating principles of mechanical calculators as well as some interactive demos
- The history of Maths has been tied up with the history of calculating devices. I was using a slide rule before the modern scientific calculator became available. The main thing is that you know what you are calculating, and can estimate the likely size of the answer.