The Ericsson and Her Engine 



The Ericsson was a finely modeled wooden ship 

 about 250 feet long, with a beam of 40 feet and depth 

 of hold of 27 feet. Her registered tonnage was 1,903. 

 By way of comparison, the Collins Line ships were 

 about 285 feet long, with a beam of 45 feet and 

 tonnage of 2,750. 



The four working cylinders of the engine, vertical 

 and in-line, each 14 feet in diameter and having a 

 stroke of 6 feet, were individually connected to four 

 supply, or compressor, cylinders, each 11}^ feet in 

 diameter. A supply cylinder was located above 

 each working cylinder. This ponderous air engine, 

 with a working displacement two and a half times 

 that of the largest steam engines, was connected to a 

 crankshaft on which turned 32-foot paddle wheels at 

 a speed of about 9 revolutions per minute. 



No drawings of the Ericsson's engine were ever 

 published, and Captain Ericsson's beautifully exe- 

 cuted working drawings have not survived; however, 

 the arrangement of each cylinder was similar to that 

 shown in figure 3, which is a copy of the patent 

 specification drawing of 1851.^ A conjectural 

 sketch of the arrangement of the driving mechanisni 

 is given in figure 5. Two sets of working and supply 

 cylinders were forward of the paddleshaft and two 

 sets were abaft of it. A pivoted horizontal working 

 beam transmitted power from the two forward units 

 through a connecting rod to the crank; a second 

 working beam and connecting rod were provided 

 for the after units. The two connecting rods shared 

 a single crankpin.^ 



The device that was designed to make possible the 

 repeated use of caloric was the regenerator. Each 

 regenerator — one was provided for each cylinder — 

 consisted of a chamber 6 feet high, 4 feet wide, and 

 1 foot thick. This space was filled with 150 sheets of 

 iron wire mesh, which had about 10 wires to the 

 inch in each direction; each wire was about a thirty- 

 second of an inch in diameter.'' 



Atmospheric air was drawn into the upper cylinder 

 as its piston moved downward, and the air was com- 

 pressed as the piston rose. When a compression 

 pressure of about 8 pounds per square inch was 



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



3 American Journal of Science and Arts [Silliman's Journal oj 

 Science], 1853, scr. 2, vol. 15, pp. 394-395. 



* The size of the mesh is derived from conflicting evidence: 

 New-York Daily Times, January 12, 1853; Appletons'' Mechanics' 

 Magazine and Engineers'' Journal, 1853, vol. 3, pp. 38, 39, 92. 



Figure 2. — John Ericsson. (From a photo- 

 graph by C D. Fredericks & Co., New York; 

 in division of mechanical and civil engineering, 

 United States National Museum.) 



reached, the compressed charge was delivered to the 

 receiver. The air from the receiver was then led 

 through the regenerator, where it was warmed by the 

 screen-wire packing of the regenerator, and into the 

 working cylinder. The furnace beneath the working 

 cylinder further heated the charge of air in the 

 cylinder; the air expanded as it was heated and thus 

 raised the piston of the working cylinder. Finally, 

 the air in the working cylinder, after it had done its 

 work on the piston, was exhausted through the re- 

 generator. The exhaust air warmed the screen-wire 

 packing, which was then ready to impart its energy 

 to the next incoming air charge. Processes of the 

 cycle are outlined in a series of sketches (figure 6), and 

 the cycle is shown on pressure-volume and tempera- 

 ture-entropy coordinates in figure 7. 



The remarkable feature of the engine, according to 

 its designer, was the ingenious employment of the re- 

 generator. In it, he said, the spent charge, being 

 exhausted from the cylinder, deposited its caloric as 

 it passed through on its way to the atmosphere. The 

 caloric, lurking among the thousands of tiny spaces 



44 



BULLETIN 228: CONTRIBUTIONS FROM THE MUSEUM OF HISTORY AND TECHNOLOGY 



