^ith Observations on different Fuels. 199 



found that the coke is altogether unnecessary, and mj' boiler is 

 worked with cinders only. 



The average daily consumption of fuel per 24 hours on the 

 whole experiment, was as follows : coke 6 J lb., cinders 21^ lb. ; 

 making a total of 27|lb. per day, say 28 lb., somethmg under 

 two thirds of a bushel.* 



Having obtained a satisfactory average with coke and cinders, 

 I next tried Welsh coal : the experiment in this case was con- 

 tinued for seven days, 6 lb. of coke were employed on the first 

 day in lighting it; and it took, in addition, 38 lb. of Welsh coal to 

 fill the furnace, and get up the heat, as the water was nearly cold. 

 After this, 19 lb. per twenty-four hours was the regular con- 

 sumption ; of which 8 J lb. were put on about 7 a. m., and 

 8^ lb. about 5 h. 30 m. p. M. The fire, of course, never went out 

 during this period ; indeed, not one third of the contents of the 

 furnace was consumed in the morning. 



Nothing can surpass the efficacy of this fuel : it burns entirely 

 away without any waste ; it produces neither clinkers nor smoke; 

 and, upon an accurate calculation, the total waste by the chimney 

 does not exceed 2^ per cent of the heat produced ; and it is more 

 durable than any other fuel. The only precaution necessary is 

 to break it to pieces about the size of eggs, or rather larger, using 

 it dust and all together. As it produces no clinkers, there is no 

 occasion to take out the fire-brick plug; and the only attention 

 requisite is to clear the bars two or three times a day ; but even 

 this is scarcely necessary if the apertures of the bars be suffi- 

 ciently large, as the coal burns entirely to dust. I find, however, 

 that it requires rather a stronger draught than other kinds of 

 fuel; so that, where it is to be permanently employed, the chim- 

 ney should be half as high again as I have recommended above; 

 say 4 ft. 6 in. instead of 3 ft. 



It will be gathered from the foregoing details that coke, by 

 itself, is not a suitable fuel for these boilers ; unless, at any time, 

 it be necessary to produce heat very rapidly. That which I em- 

 ployed is of the best and strongest quality ; but, nevertheless, all 

 coke being coarse and very porous, allows an excessive draught, 

 and burns away rapidly, wasting much heat by the chimney ; 

 and, even if this evil could be obviated, the fuel itself being so 

 very light, the furnace will scarcely contain enough to last twelve 

 hours. Its specific gravity is about half that of Welsh coal ; 

 my peck of coke weighed 8^ lb., of Welsh coal 19 lb. 



Where fuel is to be bought, unless good cinders can be 



* My bushel of coke weighed 34 lb., of cinders 38 lb. ; but, as the quan- 

 tities were taken with a gallon measure, the bushel was, I believe, a very 

 short one. I understand 40 lb. is the average weight of oven-burnt coke. I 

 presume, therefore, my cinders weighed about 45 lb. to the bushel ; but I have 

 given my quantities by weight, instead of measure, to preclude mistake. 



