The history of the CURTA calculator 

How an inventor's brilliant idea became an industrial product

Curta - Report 

"Scientific American magazine",  January 2004
Author: Cliff Stoll

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Curt Herzstark

Curt Herzstark (1902-1988) was the son of the famous Austrian manufacturer of mechanical calculators, Samuel Jacob Herzstark (1867-1937). Curt was only 3 years old when his father started producing the Austria calculator in Vienna. Curt grew up with calculators and studied mechanics. After graduating from high school, he began working in his father's business, but later joined AstraWerke and Wanderer calculator factories in Chemnitz, Germany, in order to gain experience in the production of the various machines. After spending approximately a year in Germany, Herzstark returned to the family factory in Vienna and managed the factory from 1930. 

The initial tests and the patent 

In the mid-1930s, he developed plans for a miniature circular calculator with a central stepped drum and applied for a key patent in 1938 (Deutsches Reichspatent (German Imperial Patent) №747073). In 1937, Herzstark completed the design of his universal calculator for the four basic arithmetic operations. The good times for the Herzstark family and company lasted until the end of 1937. In October, Samuel Herzstark died, and only a few months later (in March 1938), Hitler's troops invaded Austria. 

Imprisonment in Buchenwald concentration camp

From 1938 to 1943, the family factory was ordered to manufacture precision measuring instruments for the German military, and Herzstark was forbidden to continue producing and selling calculators. Curt became a target for the Germans as he was the son of a Catholic mother (Marie Amalie Herzstark) and a Jewish father. He was arrested in 1943 and taken to Buchenwald concentration camp. The SS were aware of his invention and wanted him to complete it as a gift to Adolf Hitler for the country’s final victory. This allowed Herzstark to continue developing his calculator in the secret Gustloff factory. Curt survived the concentration camp and was able to salvage the pencil drawings of the Curta he had completed there. 

Company formation in Liechtenstein

A few days after the liberation of Buchenwald, Herzstark took his drawings to Weimar and visited one of the few factories that had remained intact. Patent experts at Rheinmetallwerke in Sömmerda recognized the value of the plans and estimated worldwide demand at 10 million units. As technical director of Rheinmetallwerke, Herzstark was able to build three samples of the calculator. When Thuringia became a Russian zone and the Russians began deporting German specialists, Herzstark fled to Vienna. However, as there were no funds available in Austria to finance production, he contacted companies in Switzerland and the USA. 

When Prince Josef II became aware of the invention, it represented an opportunity to develop a precision engineering industry in the Principality of Liechtenstein after the war. Herzstark performed pioneering work in the country and developed a new factory. Herzstark became the technical director of the Contina AG calculator factory. Curt Herzstark developed the manufacturing operation under difficult conditions. Practically no skilled workers were available, the economic conditions in Liechtenstein were unfavorable. He contracted staff and the initial 2100 Curta calculators were able to be manufactured in 1947. Initially, Herzstark's invention was to be named Liliput. However, the commercial department was not happy with this name. Following a lengthy back-and-forth, a correspondent from Holland who happened to be present interjected: "The inventor's name is Curt, and the calculator is his daughter. Why don’t we just call her Curta"? 

1948 - Curta goes on sale

The Curta is launched on the market in 1948. Herzstark traveled from trade fair to trade fair and had ingenious advertisements printed. However, when an American company ordered 10,000 machines a little later, Contina's CFO rejected the order. The order was too extensive, he stated. As a result of this misguided decision, the Curta eventually only became available via mail order and in a few specialty stores. However, demand increased, and Contina was soon able to produce several hundred machines per month. 

Curta II

Just like Edison, Tesla and many other inventors, Curt Herzstark would also be cheated out of his own invention. The financial backers of Contina Werke refused to grant him the promised share package. However, since they refrained from rewriting the patents when founding the company, they were all still in Curt Herzstark's name, and they were thus no longer entitled to any rights over the successful calculator. Consequently, at least during the 1950s and 1960s, the Curta actually started making money for its inventor, and following this success, he was able to develop a second model with 15 digits instead of 11. From that point on, however, nothing much changed - apart from a few details. The machine was perfect from the start and enjoyed steady demand for two decades. "A powerful, solid, pocket-sized general-purpose calculator." The Curta was used to create balance sheets, survey maps and calculate satellite orbits.

During 1971, the last of a total of 141,187 Curtas left the production line at the plant in Liechtenstein. Herzstark had already left the Contina factory in the early 1950s, working for a few years as a consultant for German and Italian office machine manufacturers and living in a modest Liechtenstein apartment. Even geniuses found it difficult to earn millions during those days. He only received recognition for his services from the government of his adopted country at the age of 84. Curt Herzstark died on October 27, 1988, at the age of 86.

How did the Curta become a "treasure of our civilization" and a "marvel of technology?"

Why do collectors cherish these small machines, despite any cheap computer and cell phone being faster? Simple: because the impressive computational capabilities of the Curta supplement it´s precision mechanical elegance and solid reliability. The Curta combines the precision of a Swiss watch with the solid craftsmanship of a vintage Nikon F camera, packaged in a distinctive round storage box. And all this in the form of a compact cylinder, barely nine centimeters high. A portable calculator - a sensation in the 1950s! 

Source of photos & text: "Schreibmaschinenmuseum Beck, "Spektrum der Wissenschaft", "Scientific American", "Curta, Carena & Co.", "Curta Schweiz"

Old CURTA advertisements