and the Economy of Fuel. 91 



the results of these experiments indicated that not quite 

 1 3 Ibs. of ice-cold water could have been made to boil 

 with the heat furnished in the combustion of i Ib. of the 

 wood. 



The Experiments No. 22, No. 25, and No. 26, which 

 were made with the largest of my kitchen boilers, had, 

 it is true, afforded grounds to suspect that, beyond cer- 

 tain limits, an increase of size in a boiler does not tend 

 to diminish the expense of fuel in the process of heating 

 water ; yet, as all my other experiments had tended to 

 confirm me in the opinion I had at an early period im- 

 bibed on that subject, I was disposed to suspect any 

 other cause than the true one of having been instru- 

 mental in producing the unexpected appearances I 

 observed. 



I was much disappointed, I confess, at finding that 

 the brewhouse boiler, notwithstanding all the pains I 

 had taken to fit up its fire-place in the most perfect 

 manner, and notwithstanding its enormous dimensions, 

 when compared with the boilers I had hitherto used in 

 my experiments, so far from answering my expectations, 

 actually required considerably more fuel in proportion 

 to its contents than another boiler fitted up on the 

 same principles, which was not one fiftieth part of its 

 size. 



This unexpected result puzzled me, and I must own 

 that it vexed me, though I ought perhaps to be ashamed 

 of my weakness ; but it did not discourage me. Find- 

 ing, on examining the boiler, that its bottom was very 

 thick, compared with the thickness of the sheet copper 

 of which my kitchen boilers were constructed, it oc- 

 curred to me that possibly that might be the cause, or 

 at least one of the causes, which had made the consump- 



