In the late 18th century James Watt perfected the Newcomen steam engine, making it the driving force behind the Industrial Revolution. Chains synchronised with the piston's movement admitted and released steam. Watt invented the double-acting engine so that the piston could produce energy by pulling as well as pushing: the steam exerted pressure force alternately on both sides of the piston. Watt developed a parallelogram to conciliate the conflicting motions of the piston's rod, which moved up and down in a straight line, and the beam, which moved in a circle. A regulator controlled the speed by adjusting the amount of steam injected into the cylinder depending on how much power was desired. Watt also insulated the cylinder to avoid heat loss during condensation. This is a model of the machine that the Périer brothers, who introduced Watt's invention to France, built in Chaillot to supply Paris with water.