118 



OF THE GENERATION AND 



[SECT. in. 



less, and the effect less in the same ratio (see art. 331 339) ; according therefore 

 to this condition the proportion of bottom should be 



2J948JM) 



800 -t 



The side flue constantly = 2 x 1'94 = 3'88 which may be called 4 feet. 



For converting 1 cubic foot of 

 water per hour into steam. 



For sea-water, and low pressure or atmospheric steam, 



Temperature 230, 

 it requires 



f Bottom of boiler 

 I Side of do. 



4-14 

 4-0 



For converting 1 cubic foot of 

 water per hour into steam. 



205. In comparing these with the usual rules, the sum of the bottom and 

 sides must be taken ; and it may be remarked that one cubic foot of steam per 

 hour is so nearly equivalent to the horse power used in steam engine calculations, 

 for the larger kinds of engines, that they may be considered the same in these 

 comparisons. Also a bushel of Newcastle coals may be considered equivalent to 10 

 cubic feet of water converted into steam. 



Smeaton, with his wonted care, prepared a table showing the surface of boiler 

 required to be exposed to the effect of the fire and smoke for atmospheric engines, 

 and the quantity of coals to be consumed per hour. His quantity of surface for 

 1 bushel per hour is 88 feet, and for 13 bushels per hour, not quite 82 feet of 

 surface per bushel. l This is equivalent to 8'2 feet of surface for converting 1 

 cubic foot of water into steam per hour. Our deduction, from calculation, is 

 8'1 feet for low pressure steam. 



Mr. Watt says, he finds that, "with the most judiciously constructed furnace, 

 it requires 8 feet of surface of the boiler to be exposed to the action of the fire and 



Rees's Cyclopaedia, art. Steam Engine. 



