Control engineering

The tenth entry is l’accumulo dell’integratore, and the Italian says plainly what happens: the integrator goes on accumulating. English refuses the plain word and reaches for a spring. We call it « windup », and the picture is a clock being wound while the hands are held still — the tighter it is wound the longer it must take to unwind, and nothing moves until it has. That is exactly the fault: the valve is already fully open, the error will not go away, and the integrator keeps turning the key. The difficulty for a reader coming from English is that « to wind up » has wandered further from springs than almost any other phrasal verb we own. « To wind up a company » is to close it down; « to wind up a meeting » is to bring it to an end; « to wind somebody up » is to provoke them for sport; and « to wind up doing something » is to find yourself doing it after all. Only the oldest of those, the key and the spring, is the one hiding inside the control engineer’s term.