46 ANNUAL OF SCIENTIFIC DISCOVERY. 



heat used in creating the steam employed could, at the moment of 

 condensation, be reconveyed to the furnace, there again to aid in 

 producing steam in the boilers, but a very little fuel would be neces- 

 sary ; none, in fact, just enough to supply the heat lost by radiation. 

 The reason is obvious. Let us suppose the steam has passed from the 

 boiler, has entered the cylinder, has driven the piston forward, and is 

 about to pass into the condenser, there to change its form, and to be 

 again converted into water. This steam, yet in the cylinder, and 

 uncondensed, possesses all the heat it contained before passing out of 

 the boiler. It has driven the piston forward, but in that effort it has 

 lost no heat. That source of power it still contains. Let it be sup- 

 posed that the heat contained in the steam could, at the moment it is 

 converted into water within the condenser, be saved, and by some 

 device be again used to create steam from water within the boiler, 

 with what exceeding cheapness could the power of the steam engine 

 be employed. But it is quite impossible thus to re-employ the heat 

 of steam ; it cannot thus be saved : and hence every effort to econo- 

 mize in this manner would be unavailing. 



Let us now attempt to describe the regenerator, to which we have 

 referred. Without this, the machine we examined would possess, in 

 point of economy, no advantage over the best constructed steam 

 engine. With it, the advantage is incalculable. 



We have before stated that atmospheric air is first drawn into the 

 supply cylinder, whence it is forced into a receiver, and that from this 

 it proceeds toward the working cylinder, before reaching which, it 

 passes through the regenerator. This structure is composed of wire 

 net, somewhat like that used in the manufacture of sieves, placed side 

 by side, until the series attain a thickness, say of twelve inches. 

 Through the almost innumerable cells, formed by the intersection of 

 these wires, the air must pass, on its way to the working cylinder. In 

 passing through these, it is so minutely subdivided that the particles 

 composing it are brought into close contact with the metal which 

 forms the wires. Now, let us suppose, what actually takes place, that 

 the side of the regenerator nearest tlie working cylinder is heated to 

 a high temperature. Through this heated substance the air must 

 pass before entering the cylinder, and in effecting this passage, it 

 takes up, as is demonstrated by the thermometer, about 450 of the 

 480 of heat required, as we before stated, to double its volume. The 

 additional 30 are communicated by the fire beneath the cylinder. 

 The air has thus become expanded ; it forces the piston upward ; it 

 has done its work - - valves open - - and the imprisoned air, heated to 

 480, passes from the cylinder, and again enters the regenerator, 

 through which it must pass before leaving the machine. We have 

 said that the side of this instrument nearest the working cylinder is 

 hot, and it should be here stated that the other side is kept cool, by 

 the action upon it of the air entering in the opposite direction at each 

 up-stroke of the pistons. Consequently, as the air from the working 

 cylinder passes out, the wires absorb the heat so ellectually that, when 

 it leaves the regenerator, it has been robbed of it all, except about 



