C1, keyed to the engine shaft. When the driver wishes to start the engine he presses the handle towards the right, brings the clutches together, and turns the handle in a clockwise direction. As soon as the engine begins to fire, the faces of the clutches slip over one another.
THE ENGINE.
We next examine the two-cylinder engine (Fig. 42). Each cylinder is surrounded by a water-jacket, through which water is circulated by a pump9 (Fig. 43). The heat generated by combustion is so great that the walls of the cylinder would soon become red-hot unless some of the heat were quickly carried away. The pistons are of "trunk" form—that is, long enough to act as guides and absorb the oblique thrust of the piston rods. Three or more piston rings lying in slots (not shown) prevent the escape of gas past the piston. It is