THE STEAM ENGINE. 



plan in fig. 10, and in the cross section in fig. 9. The 

 of the air is represented in fig. 10 by the arrows. From the flue L 

 the air is conducted into the chimney at M. 



By such an arrangement, the flame and heated air proceeding 

 from the grate are made to circulate round the boiler, and the 

 length and magnitude of the flues through which they are con- 

 ducted should be such, that when they arrive at the chimney their 

 temperature shall be reduced, as nearly as is consistent with the 

 maintenance of draught in the chimney, to the temperature of 

 the water. 



15. The method of feeding the furnace, which has been described 

 above, is one which, if conducted with skill and care, would pro- 



Fig. 9. 



duce a much more perfect combustion of the fuel than would 

 attend the common method of filling the grate from the back to 

 the front with fresh fuel, whenever the furnace is fed. This 

 method, however, is rarely observed in the management of the 

 furnace. It requires the constant attention of the stokers (such is 

 the name given to those who feed the furnaces). The fuel must 

 14 



