In 1788 James Watt fitted his steam engines with a flyball governor, borrowed from the windmills: two iron balls on hinged arms, spun by the engine itself. Run too fast and the balls swing outward, and a linkage closes the steam valve; slow down and they drop, and it opens again. The engine minds its own speed. Except that sometimes, as engines got better, the cure set up a wobble of its own: the valve corrected a little late, the engine overshot, the governor corrected back, and the speed swung up and down around the point it was meant to hold. In 1868 James Clerk Maxwell wrote a paper, On Governors, working out with mathematics when a device built to steady a machine would make it swing instead. Hardly anyone read it for eighty years. Then in 1948 Norbert Wiener named a new science of feedback after it, cybernetics, from the Greek for steersman, partly in honour of Maxwell, because governor comes from the same Greek word by way of Latin. So the whole field takes its name from a machine whose most useful lesson was that correcting things is not the same as steadying them.