io6 Of the Management of Fire 



always be done in the largest fire-place as well, if not 

 better, than in smaller ones), as that part of the heat 

 which goes off in the smoke is indubitably lost, a ther- 

 mometer placed in the chimney would indicate, with a 

 considerable degree of precision, the perfections or im- 

 perfections of the fire-place. 



It is well known that the smoke which rises from the 

 chimneys of the closed fire-places of very large boilers is 

 much hotter than that which escapes from smaller fire- 

 places ; and I am surprised that this fact, which has long 

 been known to me, should not have led me to suspect 

 that the waste of fuel was proportionally greater in these, 

 large fire-places than in smaller ones. 



Besides the experiments of which I have given an ac- 

 count, several others were made with the new brewhouse 

 boiler ; and, among others, four experiments were made 

 on four succeeding days in brewing beer; and it was 

 found that considerably less fuel was expended in these 

 trials than was necessary in brewing the same quantity 

 of beer in the other brewhouse, in which I first intro- 

 duced my improvements. But though the alteration of 

 form, diminution of the thickness of the metal, etc., which 

 I had introduced in constructing the. new boiler and also 

 in the manner of fitting it up, had produced a consider- 

 able saving of fuel, yet it was not accompanied by a pro- 

 portional saving of time. I had flattered myself that by 

 making the boiler very thin and very shallow, I should 

 bring its contents to boil in a very short time ; but I did 

 not consider how much time is necessary for the com- 

 bustion of the fuel necessary for heating so large a quan- 

 tity of water, otherwise my expectations on this head 

 would have been less sanguine. The quantity of heat 

 generated in any given time being as the quantity of 



