1 1 2 Of the Management of Fire 



2 hours 59 minutes, with the consumption of 625 Ibs. 

 of the same kind of wood. Had the water in this 

 experiment been as cold as it was in the Experiment 

 .No. 33 (namely, at the temperature of 47), instead of 

 625 Ibs., 705 Ibs. of the fuel would have been neces- 

 sary ; and the process, instead of lasting 2 hours and 

 59 minutes, would have lasted 3 hours and 22 minutes. 



Hence we may conclude that to abridge i hour and 

 5 minutes of 3 hours and 22 minutes in the process of 

 boiling 11,368 Ibs. of water, this cannot be done at a 

 less additional expense of fuel than that of 95 Ibs. of 

 pine-wood; or, to abridge the time one third, there 

 must be an additional expense of about one eighth more 

 fuel. 



In some cases it will be most profitable to save time, 

 in others to economize fuel ; and it will always be 

 desirable to be able to do either, as circumstances may 

 render most expedient. 



From a comparison of the quantities of fuel con- 

 sumed, and consequently of heat generated, in the same 

 time, with the quantities of heat actually communicated 

 to the water in the Experiments Nos. 32 and 33 

 during this time, an idea may be formed of the great 

 quantity of heat that may remain in flame and smoke 

 after they have passed many feet in flues under the 

 thin bottom of a boiler containing cold water ; and this 

 shows with how much difficulty these hot vapours part 

 with their heat, and how important it is to be acquainted 

 with that fact in order to take measures with certainty 

 for economizing fuel. 



I have been the more particular in my account of 

 these experiments with large boilers, as I believe no 

 experiments of the kind on so large a scale have been 



