1856.] Regenerative Steam- Engine, 231 



perature might be readily supplied by means of a fire, it would not 

 be possible to give a sufficient density to the air, except by an expen- 

 diture of force in its compression. If, however, heat were applied 

 to a drop of water confined below the plunger till its temperature was 

 raised sufficiently to effect its conversion into steam of the density 

 of the water itself, (Gaignard de la Tour's state of vapours,) 

 and then allowed to expand below the plunger till its temperature 

 was reduced to zero, a dynamically perfect engine would be obtained. 

 The impracticable nature of 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 mnde strong 

 enough to bear at a temperature of more than 1000'' Fah., 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 ob- 

 taining 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 ex- 

 hibited, 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 condenser, 

 (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 oscil- 

 lating between two elastic anvils. The regenerative cylinder com- 

 municated 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 con- 

 stant 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 con- 

 sequence of this arrangement was, that while the two working trunks 

 made their strokes (the one inward and the other outward) the 

 piston of the regenerative cylinder remained comparatively quiescent 

 upon its turning or dead point, and vice versa. Around the two 



