Odds and quads

In 1623, the Tübingen-based polymath Wilhelm Schickard (1592-1635) created a wooden calculator, which he described and illustrated in two letters to the astronomer Johannes Kepler. It is not known what happened to the machine, but Goran Henriksson, now retired from Uppsala's department of physics and astronomy, believes that the numbers and construction of the device pictured are consistent with Schickard's account. Although there is no hard evidence for the identification, Swedish soldiers sacked Tübingen in 1638 and could have made off with the calculator and then donated it, along with other scientific books and instruments, to what was then Sweden's only university.

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