This was a device called The Machine. You'll see some people gathered round The Machine's outgrowths on the right and left side. They're grabbing onto long wood paddles and turning 'em in order to make The Machine's innards (a mess of gears and such) move. Over time -- we're talking a period of many-many hours, with enough human energy expended, the "arms" of The Machine would move up and down. Or was it only imperceptibly upward all week? I was never quite sure.