The main pump is not shown. Newcomen engines were extremely inefficient. The users recognized how much energy was needed. The steam cylinder was heated and cooled repeatedly, which wasted energy to reheat the steel, and also caused large thermal stresses. James Watt (1736-1819) made a breakthrough development by using a separate condenser. Watt discovered the separate condenser in 1765. (See Watt's Experiment.) It took 11 years before he saw the device in practice! The greatest impediment to the implementation of the Watt engine was the technology to make a large piston/cylinder with close enough tolerances so that they would seal a moderate vacuum. The technology improved about the same time that Watt found the financial backing that he needed through a partnership with Matthew Boulton. Principle of operation. The Watt engine, like the Newcomen engine, operated on the principle of a pressure difference created by a vacuum on one side of the piston to push the steam piston down.
