STEAM NAVIGATION. 



common land boilers, an increased evaporation in the proportion of 

 about three to two. 



The form and arrangement of the water-spaces and flues in 

 flue boilers are infinitely various. The sections of such boilers 

 are exhibited in figs. 4, 5, 6. A section made by a horizontal 



Fig. 4. 



plane passing through the flues is exhibited in fig. 4. The 

 furnaces F communicate in pairs with the flues E, the air following 

 the course through the flues represented by the arrows. The flue E 

 passes to the back of the boiler, then returns to the front, then 



Fig. 5. 



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