In 1711, this engine was introduced into mines for pumping purposes. Whether its action was originally automatic or whether dependent upon the hand operation of the valves is a question of doubt. The story commonly believed is that a boy, Humphrey Potter, in 1713, whose duty it was to open and shut such valves of an engine he attended, by suitable cords and catches attached to the beam, caused the engine to automatically manipulate these valves. This device was simplified in 1718 by Henry Beighton, who suspended from the bottom, a rod called the plug-tree, which actuated the valve by tappets. By 1725, this engine was in common use in the collieries and was changed but little for a matter of sixty or seventy years. Compared with Savery's engine, from the aspect of a pumping engine, Newcomen's was a distinct advance, in that the pressure in the pumps was in no manner dependent upon the steam pressure. In common with Savery's engine, the losses from the alternate heating and cooling of the steam cylinder were enormous. Though obviously this engine might have been modified to serve many purposes, its use seems to have been limited almost entirely to the pumping of water. The rivalry between Savery and Papin appears to have stimulated attention to the question of fuel saving. Dr. John Allen, in 1730, called attention to the fact that owing to the short length of time of the contact between the gases and the heating surfaces of the boiler, nearly half of the heat of the fire was lost. With a view to overcoming this loss at least partially, he used an internal furnace with a smoke flue winding through the water in the form of a worm in a still. In order that the length of passage of the gases might not act as a damper on the fire, Dr. Allen recommended the use of a pair of bellows for forcing the sluggish vapor through the flue. This is probably the first suggested use of forced draft. In forming an estimate of the quantity of fuel lost up the stack, Dr. Allen probably made the first boiler test. Toward the end of the period of use of Newcomen's atmospheric engine, John Smeaton, who, about 1770, built and installed a number of large engines of this type, greatly improved the design in its mechanical details. [Illustration: Erie County Electric Co., Erie, Pa., Operating 3082 Horse Power of Babcock & Wilcox Boilers and Superheaters, Equipped with Babcock & Wilcox Chain Grate Stokers]