I. Fresh air enters supply cylinder ds 

 piston moves downwdrd. 



2. Compressed dir flows from supply 

 cylinder to receiver when piston 

 nears end of upward stroke. 



3. Compressed air remains in receiver 

 during downward stroke of piston. 



4. Compressed air flows through re- 

 generator to working cylinder dur- 

 ing first part of working stroke. 



5. After cutoff, air In working cylinder 

 expands as it receives heat from 

 the furnace. 



is exhausted through the 

 ator to atmosphere. 



Figure 6. — The successive processes of the caloric engine cycle. In each 

 illustration the supply cylinder is above the working cylinder; the receiver is 

 at upper left; and the regenerator is shown as the shaded rectangle below the 

 receiver. 



as large as the Ericsson at 6)2 knots. His results ranged 

 from 247 to 276 horsepower, suggesting again that 

 the actual output of the caloric engine probably was 

 on the order of 250 horsepower. 



From the standpoint of fuel consumption, fairly 

 reliable data were available for steamships, but no 

 data were forthcoming for the Ericsson. Captain 

 Ericsson said that the actual consumption of coal was 

 6 tons, and that his furnaces could not possibly burn 

 more than 7 tons in 24 hours. When this statement — 

 made when the ship had been in operation for only a 

 few hours — was challenged, he raised his limit to 

 8 tons per day.*" Using his figure for the area of 



*" Appletons' Mechanics' Magazine and Engineers' Journal, 1853, 

 vol. 3, pp. 27, 92. 



grate surface, it would appear that a normal fire, 

 burning with natural draft, might consume about 12 

 tons of coal per day.*' A Collins liner, operating at 

 6)i knots, would be expected to burn about this 

 latter amount of coal.*^ 



The sort of testing to which Captain Ericsson's 

 caloric engines were subjected is indicated by his 

 description of his 60-horsepower engine, after which 

 the Ericsson's engine was patterned: 



<' Richard Sennet {Marine Steam Engine, ed. 2, London, 1885, 

 pp. 88, 93) gave 21 pounds per hour per square foot as about 

 the minimum consumption for a cramped boiler firebox. 



■•- Thomas Tredgold, Marine Engines and Boilers, London, n. d., 

 vol. 1, division b, p. 30; George H. Preble, Chronological History of 

 Steam Navigation, Philadelphia, 1883, p. 320; Mechanics' Maga- 

 zine, London, 1853, vol. 58, p. 324. 



PAPER 20: JOHN ERICSSON AND THE AGE OF CALORIC 



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