How it began
Curt Herzstark, an Austrian precision engineer whose father ran a calculating machine factory in Vienna, conceived the device in the 1930s and applied for his first patents before World War II. Arrested in 1943, he was sent to Buchenwald concentration camp, where he ran a precision parts department and drew up the design in his free time. After liberation in 1945 he found no backers in Vienna. Prince Franz Josef II of Liechtenstein, who wanted to build up the country's industry, took up the project. Contina AG was founded in Mauren in 1946 and production began in 1948. The design is Austrian in origin; Liechtenstein is where it was first built.
Before it existed
Mechanical calculators of the time were desk machines, and smaller devices such as adding machines handled only one kind of operation. A slide rule fit in a pocket, but Herzstark rejected it because it could not add or subtract and gave only approximate values. He wanted a completely new design, not a smaller version of an existing machine.
How it works
The Curta is a cylinder about the size of a small tin can. The first model weighed 230 grams, was 5.3 centimeters across and 8.5 centimeters high. Numbers are set with sliders around the side, and each turn of a crank on top carries out a step of the calculation. It performs all four basic operations, and square roots are possible. The Type I gave results to 11 digits and the later Type II to 15.
How it spread
Contina produced about 140,000 units, an estimated 80,000 of Type I and 60,000 of Type II. The calculator sold well despite a high price, 425 German marks in 1965. Engineering students at a school in Fribourg, Switzerland, could rent one for 20 francs a year until the 1970s. Herzstark's financial backers tried to force him out by reducing the value of the company's stock, including his one-third share, to zero, but he negotiated a new agreement.
Where it stands today
The electronic pocket calculator displaced the Curta in the 1970s. Sources give the end of production as 1970 or, according to Herzstark, 1972. Examples are held by the Smithsonian's National Air and Space Museum and the Swiss National Museum, and a computer museum in Solothurn, Switzerland, shows original models.
