A History of the Growth of the Steam-Engine

by Robert Henry Thurston

Another of the contemporaries of James Watt was a clergyman, Edward Cartwright, the distinguished inventor of the power-loom, and of the first machine ever used in combing wool, who revived Watt’s plan of surface-condensation in a somewhat modified form. Watt had made a “pipe-condenser,” similar in plan to those now often used, but had simply immersed it in a tank of water, instead of in a constantly-flowing stream. Cartwright proposed to use two concentric cylinders or spheres, between which the steam entered when exhausted from the cylinder of the engine, and was condensed by contact with the metal surfaces. Cold water within the smaller and surrounding the exterior vessel kept the metal cold, and absorbed the heat discharged by the condensing vapor.

Fig. 39.—Cartwright’s Engine, 1798.

Cartwright’s engine is best described in the Philosophical Magazine of June, 1798, from which the accompanying [sketch] is copied.

The object of the inventor is stated to have been to remedy the defects of the Watt engine—imperfect vacuum, friction, and complication.

In the figure, the steam-cylinder takes steam through the pipe, B. The piston, R, has a rod extending downward to the smaller pump-piston, G, and upward to the cross-head, which, in turn, drives the cranks above, by means of connecting-rods. The shafts thus turned are connected by a pair of gears, M L, of which one drives a pinion on the shaft of the fly-wheel. D is the exhaust-pipe leading to the condenser, F; and the pump, G, removes the air and water of condensation, forcing it into the hot-well, H, whence it is returned to the boiler through the pipe, I. A float in H adjusts an air-valve, so as to keep a supply of air in the chamber, to serve as a cushion and to make an air-chamber of the reservoir, and permits the excess to escape. The large tank contains the water supplied for condensing the steam.

The piston, R, is made of metal, and is packed with two sets of cut metal rings, forced out against the sides of the cylinder by steel springs, the rings being cut at three points in the circumference, and kept in place by the springs. The arrangement of the two cranks, with their shafts and gears, is intended to supersede Watt’s plan for securing a perfectly rectilinear movement of the head of the piston-rod, without friction.

In the accounts given of this engine, great stress is laid upon the supposed important advantage here offered, by the introduction of the surface-condenser, of permitting the employment of a working-fluid other than steam—as, for example, alcohol, which is too valuable to be lost. It was proposed to use the engine in connection with a still, and thus to effect great economy by making the fuel do double duty. The only part of the plan which proved both novel and valuable was the metallic packing and piston, which has not yet been superseded. The engine itself never came into use.

At this point, the history of the steam-engine becomes the story of its applications in several different directions, the most important of which are the raising of water—which had hitherto been its only application—the locomotive-engine, the driving of mill-machinery, and steam-navigation.