The entire operation is made perfectly clear by the aid of Fig. 1, 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.