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Calculator of the day: the Curta

This is the second in a series of six posts on Calculator of the day. Start at PART 1, continue to PART 3 or view ALL POSTS in the series.

My new book, Empire of the Sum: The Rise and Reign of the Pocket Calculator, will be published in the US on Tuesday the 22nd of August, and to mark the occasion I thought I’d post about some of my favourite calculators. This time, we’re taking a look at the “math grenade”, as William Gibson calls it in his novel Pattern Recognition — the mechanical, cylindrical, pocketable Curta.

Curta mechanical calculator with case and box.
Curta mechanical calculator with case and box. (CC BY-SA 2.0 image courtesy of Magnus Hagdorn.)

The Curta is noteworthy for two reasons. One is that it was the first practical pocket calculator, being as it was a miniaturised version of an existing mechanical calculator called the arithmometer. (The arithmometer, in turn, had its roots in a mechanism called the “Leibniz wheel”, an invention of the prolific but unlikeable Gottfried Wilhelm von Leibniz. This seventeenth-century German polymath was allegedly so unpopular that his funeral was attended only by his secretary.) With a Curta, a practiced user could add, subtract, multiply and divide numbers by adjusting a few sliders and then turning the crank on top. The answer then appeared in a set of displays arrayed around the top of the device.

It’s possible to be simultaneously entranced by the Curta’s mechanical cleverness and sobered by the circumstances of its creation. That’s because the second reason for the Curta’s prominence is that it was designed in a Nazi concentration camp. Curt Herzstark, its inventor, thinking it his only way out, designed the Curta to appease his captors — and, after the liberation of the notorious Buchenwald camp in which he was imprisoned, found his way to the tiny principality of Liechtenstein to see his blueprints put into production.

Perhaps alone among the calculators I write about in Empire of the Sum, the Curta melds tragedy and triumph in a single artefact. Herzstark’s tenacity in the face of one of the great atrocities of our time, and the ingenuity of the calculator that resulted, are equally worthy of note.

If you’d like to pre-order a copy of Empire of the Sum, this post will point you in the right direction. And don’t forget that American readers can enter a competition to win one of two copies! Visit this post to find out more.

4 comments on “Calculator of the day: the Curta

  1. Comment posted by Ralph on

    That looks like a cool device … although at a certain point of complexity my mind starts to think that it might just be easier to use pen and paper after all.

    1. Comment posted by Keith Houston on

      There are software simulations out there, such as this one, that can give you a flavour of how the Curta works. Arithmometers are essentially the same, and I think in both cases, the strength is in maintaining a running total of cumulative operations without the mental effort of carry out those operations in one’s head or on paper. The Curta really was worth it, in other words!

  2. Comment posted by Red on

    For some time now, I have been researching and documenting the Curta in all its variations and in various subject areas. A fascinating technical work of art!

    Take a look: https://curta.li/

    Kind regards from Switzerland

    1. Comment posted by Keith Houston on

      Thanks for the link! That’s a trove of information. I look forward to taking a look around.

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