John Ericsson and the Age of Caloric 



In the middle of the 19th century John Ericsson 

 built a ship poivered by an enormous caloric engine 

 that was expected to demonstrate his ' 'grand prin- 

 ciple, ' ' that heat — supposed by him and many others 

 to be a 7naterial fluid — could be used over and over 

 again as a substitute for fuel. 



At a time when the relationship betiveen heat and 

 mechanical work ivas not entirely clear, the ship's 

 trial nm excited a storm of controversy . 



A study of the details reveals the difficulties that 

 beset the engineers and scientists who ivere striving 

 to understand the laivs of thermodynamics governing 

 this relationship. 



The Author: Eugene S. Ferguson is curator of 

 the division of mechanical and civil engineering in the 

 United States National Museutn, Smithsonian 

 Institution. 



Eugene S. Ferguson 



Mus. 



Ubrahy ^ 



HARVARD 

 UNiVfiRsjr^ 



In 1852 Capt. John Ericsson built the caloric ship 

 Ericsson, intended for transatlantic service. The 

 enormous caloric engine of the Ericsson, dwarfing 

 even the largest of huge steam engines then in ex- 

 istence on land and sea, was heralded by the popular 

 press as the precursor of a new era in power generation. 



The caloric engine was a reciprocating air engine. 

 Its distinctive feature, aside from its size, was a 

 regenerator designed by Captain Ericsson to exploit 

 his "grand principle," which said that caloric (heat) 

 could be used over and over again to produce power. 

 He did not claim to be the author of the principle, 

 but he was its most ardent supporter. 



Experience and intuition told many critics that 

 there was a fallacy involved in Captain Ericsson's 

 reasoning, but few of these critics could explain 

 clearly and convincingly just why caloric could not 

 be used more than once. 



One might suppose that the caloric theory, in 

 which a subtle elastic fluid called caloric was used 

 to explain the observed phenomena of heat flow, had 



quietly expired when the mechanical equivalent of 

 heat (one B.t.u. = 778 ft. -lb.) had been determined in 

 the 1840's. And no doubt the theory would have 

 expired had not Captain Ericsson announced his 

 support of it in such tangible form. If the Ericsson 

 had not been built, it is likely that, as the emerging 

 science of thermodynamics was reported in the 

 journals of learned societies, only an occasional 

 "hear, hear!" would have punctuated the gradual 

 process of correction and clarification; on the other 

 hand, we now should know a great deal less about 

 the intellectual climate into which the new theories 

 were being introduced. 



The decade before the Civil War had more than 

 its share of monumental engineering works. The 

 Crystal Palaces in London and in New York, John 

 Roebling's 800-foot Niagara span, the great iron 

 ship Great Eastern, the Atlantic Cable, Pennsylvania's 

 Horseshoe Curve, and the Collins Line steamships 

 crossing the North Atlantic on a schedule that defied 

 wind and tide, all were accomplishments that have 



42 



BULLETIN 228: CONTRIBUTIONS FROM THE MUSEUM OF HISTORY AND TECHNOLOGY 



