"At first [Newcomen] made a double cylinder, using the space between for condensing water. This was not very satisfactory. The vacuum was secured very slowly and imperfectly. In 1711 they attempted to erect an engine for draining a mine, but failed. The next year they succeeded... but it was slow and ineffective. To operate it, required two men and a boy. The boy's work was to alternately open and close the valves to the condensing water and to the boiler. One day the engine made two or three motions quickly and powerfully. Newcomen immediately examined the cylinder and found a small hole, through which a small jet from the water that was on top of the piston to make it steam tight, was spurting into the cylinder. He appreciated the significance... [and] dispensed with the outer water jacket and injected the water for condensation, through a small pipe in the bottom of the cylinder. It... increased the speed of the engine from eight to fifteen strokes a minute, besides getting the advantage of a good vacuum. In 1713 a pump was erected in , and the boy who was hired to open and shut the valves, in an effort to make his work easier, rigged up a contrivance of strings and levers that operated the valves from the motion of the working beam over head. This made the engine automatic and marked another stage in its evolution. This boy, Humphrey Potter... This valve motion was afterward improved by in 1718. This engine... continued to be until the days of Watt..."