William Stanley Jevons completed his keyboard-operated “Logic Piano” around 1869 and described it in “On the Mechanical Performance of Logical Inference,” read before the Royal Society on 20 January 1870. About the size of a small upright piano, it took in the premises of a problem through a row of keys and let its internal rods and levers eliminate the combinations the premises ruled out, displaying the consistent conclusions on a board of letters. It was the first device to solve a logic problem faster than a human could without it, turning George Boole’s symbolic logic from a notation on the page into the operation of a physical machine.