All About Engines

The Pioneers before Watt 31 was familiar with the work of Papin and Savery. In 1705 he made a model engine which was an im- provement on the others. It consisted (see Fig. 15) of a boiler with a furnace beneath it and a cylinder above. The cylinder was provided with a piston which was forced up- wards when steam was ad- mitted below. The cylinder being then cooled by im- mersion in water, the steam was c o n d e n sed, and the piston Fig. 15.—Newcomen’s engine descended, partly by its own weight and partly by the pressure of the atmosphere on its upper surface. On this account the engine was called an “atmo- spheric ” engine. The piston was connected with one end of a beam, to the other end of which was attached the rod of a pump. When the steam piston was forced upwards the pump piston, or “ bucket,” as it is often called, fell, forcing up the water in the pump barrel by its own weight, as the steam piston fell under the pressure of the atmosphere, the pump piston rose, and water from the well flowed into the pump barrel. This model worked satisfactorily, but it was six years before Newcomen could get an order for a full-