What is a portable hand-cranked calculator 'Kurta calculator' invented by a prisoner in a Nazi concentration camp?


Morgan Davis

Today, many people use smartphone calculator apps, but in the past, mechanical calculators were used instead of electronic calculators. Since its appearance in 1948, the ' Kurta Calculator ', which has been the best portable calculator on earth for about 20 years, is said to have been invented by a prisoner who was held in a Nazi concentration camp. Ars Technica summarizes its history.

The hand-cranked calculator invented by a Nazi concentration camp prisoner | Ars Technica

In the past, people had no choice but to use paper and pens to perform calculations that were too complicated to be mentally calculated. In the 17th century, the slide rule , an analog calculation tool that applied the principle of logarithm , was invented, allowing people to perform complex calculations without paper or pens, but the slide rule was limited to the number of digits it could handle. had. Also, in the 19th century, mechanical calculators using mechanisms such as gears were mass-produced, but they were all heavy and expensive.


Joe Haupt

Kurt Herzstark, an Austrian Jew born in Vienna, Austria in 1902, was involved in the family business of manufacturing and selling office equipment. Sold. Although mechanical calculators at the time were quite sophisticated, Herzstark began to realize that there was a demand for 'portable size calculators' while engaging with customers. 'People kept saying, 'That's good, but don't you have something smaller?'' Herzstark recalled.

In devising a smaller and more portable mechanical calculator, Herzstark thought that it was not enough to keep the existing design as it was and make all the parts smaller, and that a drastic redesign was necessary. 'What kind of shape can such a machine be used? A cube or a ruler is no good. It must be cylindrical so that it can be held with one hand.' Then you can adjust it with the other hand... We started by designing the ideal car from the outside, before designing the inside,' recalls Herzstark.

Based on the design of a cylinder that can be held with one hand, Herzstark entered the design of a mechanism for entering numbers by rotating a slider with a finger. Then, by placing a rotating step drum in the center of the machine and making the two teeth attached to the drum correspond to addition and subtraction, we devised a method to switch between addition and subtraction just by shifting the drum a few millimeters. Furthermore, by flipping the slider and rotating the crank, we succeeded in supporting multiplication and division.

As of 1937, Herzstark had already completed the essential design of a portable mechanical calculator. After that, it was only a stage of machining parts and manufacturing prototypes, but Nazi Germany will rise here.

Austria was annexed by Nazi Germany in 1938, and Herzstark, who has a Jewish father, is also in danger. Fortunately, the Herzstark family was able to keep the factory running for several years by producing machines and tools for the German army, but in 1943 an employee was arrested for listening to British radio. Herzstark, who was asked to testify, was also deported to a concentration camp.

Herzstark was imprisoned in the Buchenwald concentration camp in central Germany. In her memoirs of the time, Herzstark said, 'If the Nazis hanged someone, I had to watch them die. It was terrible.'

Herzstark was forced to work at a factory that manufactured German V2 rockets , but eventually a senior German engineer took out Herzstark and ordered him to develop a small computer. The engineer gave Herzstark the equipment necessary for the design, and if he could give Hitler a small calculator after winning the war, Herzstark would also be able to become an Aryan.

Herzstark, who managed to survive the camp life through preferential treatment, walked to the city of Weimar about 7 km away with the blueprints when the prisoners of the Buchenwald concentration camp were released on April 11, 1945. We found a working factory and successfully built a prototype. However, shortly after that, the Soviet army got on board, so Herzstark fled to Vienna with a box containing computer parts.

After the war, Herzstark became the technical director of a company called Contina AG Mauren with the support of the Liechtenstein government, which was interested in small mechanical calculators. In 1948, the first model of the 'Kurta Calculator', a portable mechanical calculator, was finally released.


Matt Blaze

The Kurta Calculator gained popularity among accountants, engineers, surveyors, rally car drivers, and observatory researchers, and in 1954, a second-generation model with an increased number of digits was released. Astronomer Peter Boyce, who has used the Kurta calculator when he was a graduate student, remembers the Kurta calculator as a ``wonderful precision machine''. Experienced users were also able to do calculations without looking at their hands, saying, 'It was helpful to bring it into the telescope and use it instead of pencil and paper when I needed to do some calculations at 2am. ' said Boyce.

A total of 150,000 Kurta calculators were manufactured for about 20 years until small calculators became popular, and the last one was shipped in 1972. Herzstark continued to live in Liechtenstein and died in 1988 at the age of 86.

``The Kurta calculator was one of the most sophisticated and most successful calculators invented in the 20th century,'' said Aina Prinz, director of the Mathematical Museum and Arithmeum in Germany. If you look at it, there's very little you can cut mechanically if you want it to be finger-operable.'

Even at the time of writing the article, it seems that there are no users who are actively using the Kurta calculator, but sometimes forgotten Kurta calculators can be found in the basement or attic, and on eBay it costs between $ 1,400 and $ 3,000 (approximately 180,000). It is said that it is sold for 8000 yen to about 403,000 yen).

by gorekun

in Hardware,   Science, Posted by log1h_ik