Handheld or Handgrenade?
Actually, the iPhone of its day. This is a Curta mechanical calculator developed by Curt Herzstark in Vienna, Austria. It fit easily in the palm of your hand and was able to perform addition, subtraction, multiplication and division. The progeny of Leibniz’s Stepped Reckoner, the Curta used a combination of gears invented by Leibniz along with a crank on the top which moved numbers into the machine and was also used to select which mathematical function to use.
Herzstark thought of the design in the 1930s and, by 1938, had filed a patent on it. He was unable, however, to produce it before the beginning of the second world war. In 1938 the Nazis forced his company to build other precision instruments for the German army and, in 1943, Herzstark (whose father was Jewish) was arrested and sent to the Buchenwald concentration camp. At Buchenwald, he was forced to make drawings of his calculator so that the Nazis could manufacture it.
Before that could happen, though, Buchanwald was liberated and Herzstark was able to reconstruct his drawings from memory and began manufacturing the Curta after the war. Curtas were the best portable calculators until the advent of electronic calculators in the 1970s. It’s amazing that this device was the state of the art up to fifty years ago and had more in common with the Leibniz device invented around 1673 than the electronic calculators that came after it.
For more on the Curta, click here.