There is a fundamental principle involved in the "regen- 

 erator" of Ericsson, Stirling, and others, which, could it be 

 employed without drawbacks or losses, would allow one 

 ounce of coal per day to pump out the Niagara river, and 

 keep it dry. 



Professor Pierce, in the American Academy of 

 Arts and Sciences, said that he considered the idea 

 that heat cannot be used over and over again to be a 

 fundamental rule, which has only a single exception, 

 that of steam . . . ." ^ Evea the brilliant Lord 

 Kelvin, as late as 1848, said: " 



The conversion of heat into mechanical effect is probably 

 impossible, certainly undiscovered. . . . This opinion 

 seems to be nearly universally held. ... A contrary 

 opinion, however, has been advocated by Mr. Joule of 

 Manchester, some very remarkable discoveries which he 

 has made . . . seeming to indicate an actual conversion of 

 mechanical effort into caloric. No experiment is adduced 

 in which the converse operation is exhibited .... 



By 1853 Lord Kelvin had resolved his difhculty, but 

 among practicing engineers the 1848 ideas persisted 

 for many years longer. 



The reason is quite understandable for the per- 

 sistence of the belief that no heat was consumed in 

 passing through a steam engine. Because of the low 

 thermal efficiency of steam engines then in use (on 

 the order of 2 to 5 percent) and the difficulty of 

 measuring the quantities of heat involved, any dis- 

 crepancy between the heat added to and removed 

 from the steam cylinder was charged to a loss by 

 radiation. 



The carefully controlled experiments by Regnault 

 in Paris finally established a measurable difference 

 between the heat added to steam in a boiler and the 

 heat rejected to a condenser. Regnault's results 

 complemented those of Jottle. Regnault showed 

 that heat could be converted to work; Joule, that 

 work could be converted to heat. 



On reading very carefully the several patent specifi- 

 cations of Captain Ericsson, one will always find a 

 clause that tends to prove that the inventor was not 

 trying to get more energy from a fuel than it con- 

 tained, but that he wanted merely to utilize the 

 energy in its entirety. In his 1851 patent ^- appears 

 the paragraph: 



*'" Proceedings of the American Academy of Arts and Sciences, 

 1852-1857, vol. 3, p. 28. 

 81 Quoted in Keenan, op. cit. (footnote 50), p. 82. 

 62 U.S. Patent 8481, November 4, 1851. 



Accordingly, while in the steam-engine the caloric is 

 constantly wasted by being passed into the condenser or by 

 being carried off into the atmosphere, the caloric is [in the 

 caloric engine] employed over and over again, dispensing 

 with the employment of combustibles, excepting for the 

 purpose of restoring the heat lost by the expansion of the 

 acting medium and that lost by radiation; also for the pur- 

 pose of making good the small deficiency unavoidable in 

 the transfer and retransfer of the caloric. 



The phrase "heat lost by the e.xpansion of the acting 1 

 medium," if construed as the mechanical equivalent 

 delivered to the working piston, acquits Captain 

 Ericsson of the charge that he was proposing a 

 perpetual motion device. But even this point is ob- 

 scured by his statement, in another place, that the 

 actual "loss of heat" by this expansion was "two 

 ounces of coal per hour per horse-power." He used 

 a heating value for coal of 11,000 British thermal 

 units per pound. ^' Had he recognized the signifi- 

 cance of mechanical equivalent of heat, which had 

 been determined experimentally by Joule several 

 years earlier,^* he might have avoided the statement 

 that 0^X11,000=) 1,375 British thermal units of 

 heat would produce one horsepower-hour (or 2,545 

 Btu) of work. There was so much conflicting evidence 

 being published in the various technical journals 

 at the time, however, that Captain Ericsson can 

 perhaps be excused for not extracting from the welter 

 of confusion the simple fact that was later recognized 

 as the key to the First Law of thermodynamics. 



But if Captain Ericsson did not attempt to violate 

 the First Law, which is unlikely, it is certain that his 

 theory of heat was in direct opposition to the Second 

 Law of thermodynamics. If he accepted the con- 

 clusion of Regnault as fact, and admitted that 5 

 percent of the heat had been converted to work, he 

 might immediately say: "Yes, but there is still a 

 waste of 95 percent; I will recover that." There 

 was, in 1853, no clear explanation why that was not 

 possible. 



The Second Law, in terms of everyday experience, 

 says that heat will not, of its own accord, flow from a 

 lower to a higher temperature. This leads to the 

 corollary pertinent to the caloric engine: No heat 

 engine, taking heat from a single source, can convert 

 all the heat to work and produce no other effect. 



63 Appletons' Mechanics' Magazine and Engineers' Journal, 1853, 

 vol. 3, p. 38. 



"■' The order of development is tabulated in Minutes of 

 Proceedings of Institution of Civil Engineers, 1853, vol. 12, p. 574. 



54 



BULLETIN 228: CONTRIBUTIONS FROM THE MUSEUM OF HISTORY AND TECHNOLOGY 



