Page:Popular Science Monthly Volume 57.djvu/604

594 which is a simple diagram of a single cylinder motor. The chamber R contains the gasoline. Air enters this chamber through tube b, as indicated by the arrow, and passes out between the plate c and the surface of the gasoline. The float d keeps the plate c in the proper position regardless of the amount of liquid in the reservoir. The heated gases exhausted from the cylinder pass through the pipe r, and thus heat the gasoline so that it vaporizes freely and the air passing under c becomes charged with the necessary proportion of vapor. The mixed air and vapor enter a valve chamber S, from which the flow into pipe e is regulated by the movement of handle a. In this chamber there is another valve, operated by an independent handle, and by means of this more air can be admitted into the mixture when desired. Through the pipe e and the valve f the vapor enters chamber Q, which connects with the top of the cylinder. Suppose the shaft G is rotating, then the piston will be drawn down from the position in which it is shown and thus a vacuum will tend to form in chamber Q. This action will cause the valve f to open and the mixture of air and vapor will flow into Q until the piston reaches its lowest position and begins to ascend. At this instant the valve f will close, and then the upward movement of the piston will compress the mixture in the chamber Q. When the piston reaches the upper position, after completing the down and up strokes, the lever l and the contact point p will come together, and an electric current developed in the induction coil M will pass through the wires j and k and produce a spark at i between the ends of the metallic terminals passing through the plug of insulating material, which is shown in dark shading. This spark will cause the mixed air and vapor to ignite, producing an explosion that will force the piston down for the second time. On the second upward movement of the piston the gases produced by the combustion of the vapor will be forced out through the valve h into the chamber T and the pipe r. The valve h and the lever l are operated by cams mounted on the shaft m, and they are so set that the spark at i occurs when the chamber Q is full of the explosive mixture and the piston is at the top of the cylinder. The valve opens when the piston begins to move upward after the explosion has forced it to the bottom position.

As will be seen, the piston must move down to draw in a supply of the explosive mixture; it then moves upward to compress it, and on the second down stroke it is pushed by the force of the explosion. From this action it can be clearly realized that the power developed by the motor comes from the force exerted by explosions at every alternate revolution of the shaft. On that account the cams that move the valve h and the lever l are placed on a separate shaft, which is geared to the main shaft in the ratio of two to one; that is, the wheel K is twice the diameter of the wheel J. As the force of the piston acts on