Before electronic calculators and computers swept them all away there were a wide range of mechanical calculators, ranging from hand held devices like the Arithma pocket calculators and slide rules to heavy desktop machines. It seems strange, when computers are so much part of our lives, that only thirty years ago anybody who needed to do some ad hoc calculations had three choices. They could use mental arithmetic, they could look up the answers in a book of tables, or they could use one of the mechanical calculators.
Punched card machines and primitive electronic computers were available for repetitive data processing, but they were hard to program and had not much more computing power than a modern pocket calculator.
The most elegant and collectable of the old mechanical calculators is the Curta. This hand held device is a beautifully designed four function mechanical calculator. The Curta is about 4.5” high and 1.5” in diameter and is a masterpiece of mechanical engineering. It was designed by an Austrian called Curt Herzstark. Herzstark completed the drawings for the Curta in 1938; then the war intervened and prevented the machine being put into production.
In 1943 Herzstark was sent to the Buchenwald concentration camp for “helping Jews and subversive elements”. In the camp he was designated an “intelligence slave” [catchy title] and set to work in the camp’s factories. The camp commandant knew of Herzstark’s work on the Curta and he was set to work redrawing the calculator blueprints from memory. The commandant’s idea was to build a calculators and present it to Hitler after the war ended. After the Allies bombed the camp Herzstark was transferred to a deserted salt mine nearby and continued work on the Curta 600 metres below the surface.
After the war Herztark moved to Liechtenstein and a factory was built to produce the Curta. The calculator sold well because there was nothing like it on the market and production continued until 1972. By then 140,000 units had been produced.
For more information see the Curta Page on the internet. The site sells a beautifully produced exploded parts diagram of the Curta. I have one framed on my study wall.