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A.M. Stephenson Adding Machine Review / HowTo

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The Sector: the calculator of the 1500s

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Aphon Chilam Koto

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Walther made a calculator! Walther WSR-160 Review / HowTo

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Why Are Cooling Towers Shaped Like That?

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Finally! A Cheap and Accurate Infrared Thermometer!

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Why do hurricane lanterns look like that?

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It finds the derivative: The Ott Derivimeter (1930s)