278 



THE POPULAR SCIENCE MONTHLY. 



The fire-box, N JV, is of steel, six feet two inches long outside, 3 

 feet wide, and five feet four inches high. The tubes, 0, are of iron, 

 142 in number, 2J inches diameter, and eleven feet seven inches long. 

 The steam-dome, E, is thirty inches outside diameter, the smoke- 



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stack, ^>, 14 inches. The feed-water is supplied by one pump, h, of 

 2\ inches diameter and two feet stroke, and by a No. 8 Giftard in- 

 jector. The valves, T, are 16 inches wide by 8* inches long, and 

 have five inches travel. The steam-ports are 15ff inches wide and 

 li inch long, and the exhaust-port 15-f| by 2| inches. The lap of the 



