1 1 6 Of the Management of Fire 



but there seems to be much reason to suspect that the 

 expense of fuel, in working those engines, is consider- 

 ably greater than it ought to be, or than it would be, 

 were the boilers and fire-places constructed on the best 

 principles, and the fire properly managed. 



In attempts to improve, it is always very desirable 

 to know exactly what progress has been made, to be 

 able to measure the distance we have laid behind us in 

 our advances, and also that which still remains between 

 us and the object in view. The ground which has 

 been gone over is easily measured ; but to estimate 

 that which still Iks before us is frequently much more 

 difficult. 



The advances I have made in my attempts to im- 

 prove fire-places, for 'the purpose of economizing fuel, 

 may be estimated by the results of the experiments of 

 which I have given an account in this Essay ; but it 

 would be satisfactory, no doubt, to know how much 

 farther it is possible to push the economy of fuel. 



In my 4th Experiment, 7^f Ibs. of water, at the tem- 

 perature of 58, were made to boil, at Munich, with 

 6 Ibs. of wood. If, from the result of this experiment, 

 we compute the quantity of ice-cold water which, with 

 the heat generated in the combustion of i Ib. of the 

 fuel, might be heated 1 80, or made to boil, it will turn 

 out to be only i| Ib., or more exactly i.i i Ib. 



According to the result of the Experiment No. 20, 

 it appeared that no less than 2Oyo Ibs. of ice-cold water 

 might have been made to boil with the heat generated 

 in the combustion of i Ib. of pine-wood. 



It appears, therefore, that about eighteen times as 

 much fuel, in proportion to the quantity of water 

 heated, was expended in the Experiment No. 4, as in 



