The methods used during the eighteenth century to regulate the power output of the steam engine are examined. Both open and closed loop systems are considered ; these include load regulation, engine stroke length and frequency control, boiler water level and pressure control, uses of energy storage devices—fly-wheel, accumulator—and the flyball or Watt governor. It is shown that although some closed loop systems were used, the engineers of the time were unaware of the importance of ‘feedback’, the main emphasis was on obtaining static equilibrium of the system. It was through the economic theories of the period that an understanding of the concept of feedback emerged.