MARINE BOILERS. 



to the back again, and is finally carried back to the front, where 

 it communicates at c with the curved flue B, represented in the 

 transverse vertical section, fig. 5. This curved flue B finally 

 terminates in the chimney A. There are, in this case, three inde- 

 pendent boilers, each worked by two furnaces communicating with 

 the same system of flues ; and in the curved flues B, fig. 5, by 

 which the air is finally conducted through the chimney, are placed 

 three independent dampers, by means of which the furnace of 

 each boiler can be regulated independently of the other, and by 

 which each boiler may be separately detached from communication 

 with the chimney. 



A longitudinal section of the boiler, made by a vertical plane 

 extending from the front to the back, is given in fig. 6, where F, 

 as before, is the furnace, G the grate-bars sloping downwards 

 from the front to the back, H the fire-bridge, c the commencement 

 of the flues, and A the chimney. An elevation of the front of the 



boiler is represented in fig. 7, showing two of the fire-doors closed 

 and the other two removed, displaying the position of the grate- 

 bars in front. Small openings are also provided, closed by proper 

 doors, by which access can be had to the under-side of the flues, 

 between the foundation timbers of the engine, for the purpose of 

 cleaning them. 



Each of these boilers can be worked independently of the others. 

 By this means, when at sea, the engine may be worked by any 

 two of the three boilers, while the third is being cleaned and put 

 in order. 



In the boilers here represented the flues are all upon the same 

 level, winding backwards and forwards without passing one above 

 the other. In other boilers, however, the flues, after passing 

 backwards and forwards near the bottom of the boiler, turn 



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