.S7A 1 WILLIAM SIEMENS, I-.K.S. 55 



such an engine was however manifest, if it was considered that 

 steam of the density of the water producing it, would exert a 

 pressure of probably several hundred atmospheres, which pressure the 

 moving part of the engine must be made strong enough to bear at 

 a temperature of more than 1000 Fahr., and that the capacity of 

 the working cylinder must be sufficient to allow of an expansion of 

 the steam to several thousand times its original volume. It was 

 therefore necessary to look for other means of obtaining from heat 

 its equivalent value of force, which means, it was contended, were 

 furnished by the "regenerative steam-engine." 



This engine, of which several diagrams and a model were 

 exhibited, consisted of three essential parts, namely, the furnace ; 

 the working cylinder, with its respirator and heating vessel ; and 

 the regenerative cylinder. It consisted also of a boiler and con- 

 denser, (unless the steam were discharged into the atmosphere,) 

 but these were not essential to the working of the engine, although 

 of great practical utility. The regenerative cylinder had for its 

 object alternately to charge and discharge two working cylinders, 

 and the action of its piston might be compared to that of a hammer 

 oscillating between two elastic anvils. The regenerative cylinder 

 communicated at its one extremity with one working cylinder, and 

 at the other extremity with another and similar working cylinder, and 

 these communications were not intercepted by valves. The working 

 cylinders were so constituted that their capacity for steam of 

 constant pressure was the same, no matter where the working 

 piston stood. Each consisted of a cylinder of cast iron, open at 

 both ends, which was completely enclosed in another cylinder or 

 heating vessel, one end of which was exposed to the action of 

 a fire. Within the inner cylinder was a large hollow piston, 

 filled with non-conducting material, to which was attached a 

 long trunk or enlarged hollow piston rod of nearly half the 

 sectional area of the piston itself. This trunk was attached to 

 the working crank of the engine in the usual manner. The 

 trunk of the second working cylinder stood precisely opposite, 

 and was connected with the same crank. The piston of the 

 regenerative cylinder was also connected with the same crank; 

 but stood at right angles to the two working cylinders. The 

 consequence of this arrangement was, that while the two working 

 trunks made their strokes (the one inward and the other out- 



