MECHANICS AND USEFUL ARTS. 47 



30. In other -words, as the air passes into the working cylinder, it 

 gradually receives from the regenerator about 450 of heat ; and as 

 it passes out, this is returned to the wires, and is thus used over and 

 over, the only purpose of the fires beneath the cylinders being to 

 supply the 30 of heat we have mentioned, and that which is lost by 

 radiation and expansion. Extraordinary as this statement may seem, 

 it is nevertheless incontrovertibly proved by the thermometer, to be 

 quite true. 



The regenerator contained in the sixty-horse engine we have 

 examined, measures twenty-six inches in height and width internally. 

 Each disc of wire composing it contains 676 superficial inches, and 

 the net has ten meshes to the inch. Each superficial inch, therefore, 

 contains 100 meshes, which multiplied by 676, gives 67,600 meshes, 

 in each disc, and as 200 discs are employed, it follows that the regen- 

 erator contains 13,520,000 meshes, and consequently, as there are as 

 many small spaces between the discs as there are meshes, we find that 

 the 'air within it is distributed in about 27,000,000 minute cells. 

 Hence, it is evident, that nearly every particle of the whole volume 

 of air, in passing through the regenerator, is brought into very close 

 contact with a surface of metal, which heats and cools alternately. 

 The extent of this surface, when accurately estimated, almost sur- 

 passes belief. The wire contained in each disc is 1,140 feet long, and 

 that contained in the regenerator is consequently 228,000 feet, or 41^- 

 miles in length, the superficial measurement of which is equal to the 

 entire surface of four steam-boilers, each forty feet long, and four feet 

 in diameter ; and yet the regenerator, presenting this great amount of 

 heatino- surface, is onlv about two feet cube less than 1-1920 of the 



C 1 v 



bulk of these four boilers. 



Involved in this process, of the transfer and retransfer of heat, is a 

 discovery which justly ranks as one of the most remarkable ever 

 made in physical science. Its author. Captain Ericsson, long since 

 ascertained, and upon this based the sublimest feature of his caloric 

 engine, that atmospheric air and other permanent gases, in passing 

 through a distance of onlv six inches, in the fiftieth part of a second 



fi 



of time, are capable of acquiring or parting with, upward of four 

 hundred degrees of heat. He has been first to discover this marvel- 

 lous property of caloric, without which, atmospheric air could not be 

 effectively employed as a motive power. The reason is obvious. 

 Until expanded by heat, it can exert no force upon the piston. If 

 much time were required to effect this, the movement of the piston 

 would be so slow as to render the machine inefficient. Captain Erics- 

 son has demonstrated, however, that heat may be communicated to, 

 and expansion effected in, atmospheric air, with almost electric speed ; 

 and that it is, therefore, eminently adapted to give the greatest desir- 

 able rapidity of motion to all kinds of machinery. 



In order to afford a practical trial of the caloric engine upon a 

 large scale, a gigantic vessel has been built, and fitted with engines 

 constructed on the principles described. This vessel is said to be the 

 finest specimen of naval architecture, (especially in point of strength 

 5* 



