48 THE SCIENTIFIC PAPERS OF 



external cylinder was heated by a fire to 050 Fahr., as indicated 

 by the pyrometer, and was maintained at that temperature. 



A second, or charging cylinder was provided, which by the 

 motion of its working piston, alternately withdrew and returned 

 the same air to the first cylinder. The capacity of the charging 

 cylinder was 24 cubic feet, and its piston made 18 strokes per 

 minute : about two-thirds of its contents, or 10 cubic feet of air 

 of atmospheric pressure, passed with each stroke, to and fro 

 through the respirator, and all the heat carried away was absorbed 

 by the sides of the cylinder. After 2f hours' working, the tem- 

 perature of the charging cylinder was raised from 60 to 110 Fahr. 

 (50). Its capacity for heat had been previously ascertained, by 

 suddenly admitting steam, and weighing the condensed water 

 obtained (in heating it from (50 to 210 Fahr.) (150), which 

 amounted to about 541bs. The quantity of air which passed 

 from the respirator into the cylinder was 43,200 cubic feet, and 

 its weight 3360 Ibs. : this, if multiplied by its specific heat 0'2G7, 

 is equal to 897 Ibs. of water-power of absorbing heat. The heat 



given off was- 1000 = 18000 units, and consequently the 

 air left the respirator, each time, at a temperature of - = 20*01 



OtJ / 



nigher than that at which it entered. Adding to this, for loss of 

 heat by radiation during the experiment, which according to 

 established rules may be taken at 5, the entire loss of heat by 

 the respirator amounts to 25 Fahr. when air is employed. In 

 using steam it does not exceed 10 Fahr., owing to the greater 

 conducting power of that fluid. 



The regenerator condenser, which was designed and executed 

 some years ago by the author, is an illustration that water may 

 be also subjected to respirative action. 



The paper is illustrated by a series of diagrams from whence 

 Plate 5 is compiled. 



MR. SIEMENS explained, that the diagrams were chiefly intended 

 to illustrate the peculiar functions of the "respirator," or as 

 Mr. Ericsson had termed it, the " regenerator." Very conflicting 

 opinions had been expressed regarding this most essential element 

 in Ericsson's engine. Some thought that, by its agency, the heat 



