and the Economy of Fuel. 117 



the No. 20 ; and hence we may conclude with the 

 utmost certainty, that of the heat generated, or which 

 with proper management might have been generated, in 

 the combustion of the fuel used in the 4th Experiment, 

 less than -jV part was employed in heating the water, 

 the remainder, amounting to more than -J of the whole 

 quantity, being dispersed and lost. 



I ventured to give it as my opinion, in the beginning 

 of this Essay, that " not less than seven eighths of the 

 heat generated, or which with proper management 

 might be generated, from the fuel actually consumed, 

 is carried up into the atmosphere with the smoke, and 

 totally lost." I will leave it to my reader to judge 

 whether this opinion was not founded on good and 

 sufficient grounds. 



But though it be proved beyond the possibility of a 

 doubt that the process of heating water was performed 

 in the 2oth Experiment with about -f s part of the pro- 

 portion of fuel which was actually expended in the 4th 

 Experiment, yet neither of these experiments, nor any 

 deductions that can be founded on their results, can 

 give us any light with respect to the real loss of heat, 

 or how much less fuel would be sufficient were there 

 no loss whatever of heat. The experiments show that 

 the loss of heat must have been at least eighteen times 

 greater in one case than in the other; but they do 

 not afford grounds to form even a probable conjecture 

 respecting the amount of the loss of heat in the experi- 

 ment in which the economy of fuel was carried the 

 farthest, or the possibility of any farther improvements 

 in the construction of fire-places. I shall, however, by 

 availing myself of the labours of others, and comparing 

 the results of their experiments with mine, endeavour 

 to throw some light on this abstruse subject. 



