Figure 23. — Steam velocipede built by Sylvester H. Roper about 1869. Only 

 one older self-propelled road vehicle, the Dudgeon steamer, is known to exist 

 in America. 



Oscillating steam cylinders (fig. 24) are pivoted on each 

 side of the frame, next to the chimney. From measure- 

 ments of the outside of the cylinders it is estimated that 

 their bore is about 2 ! /4 inches. The piston rods work on 

 2 V^ -inch cranks on the ends of the rear axle. Piston valves 

 for the cylinders are operated by eccentrics adjacent to 

 their cranks. A feed-water pump is operated by the crank 

 of the left cylinder. The exhaust steam is led by tubing 

 into the base of the chimney to provide a forced draft. 

 Projecting from the safety valve at the top rear of the 

 boiler is a tiny steam pipe, also leading into the base of the 

 chimney, that apparently performed the same function 

 when the machine was at rest. A damper valve is located 

 within the chimney. 



34 



