The Curta is the smallest mechanical calculator ever made — a precision instrument the size of a pepper grinder that performs all four arithmetic operations.
1938: Austrian inventor Curt Herzstark began designing a pocket calculator at his family's precision instrument factory in Vienna.
1943: Herzstark, half-Jewish, was arrested and sent to Buchenwald concentration camp. The Nazis, aware of his engineering genius, allowed him to continue developing the calculator — intending it as a gift for Hitler after the war.
1945: Herzstark emerged from Buchenwald with the complete design in his head. He had refined every gear, every cam, every mechanism during his imprisonment.
1948: The first Curta Type I was manufactured in Liechtenstein. It contained 605 precision parts and could perform addition, subtraction, multiplication, and division.
How it works: Set numbers using the side sliders. Turn the crank in normal position to add. Lift the crank and turn to subtract. Multiply by repeated addition with carriage shifts. About 150,000 Curtas were produced before electronic calculators made them obsolete in the 1970s.
“To have come up with such a design under those circumstances is one of the most remarkable feats of engineering in history.”