BOILEE No. 24. 129 



Boiler pressure, 80 Ibs. 



Temperature of feed- water, . . . . . . .44 cleg. 



Temperature of escaping gases, 316 cleg. 



Draught suction, 0.32 in. 



Water per pound of coal, . . . . . . .7.52 Ibs- 



Water per pound of coal from and at 212 degrees, . . 9.10 Ibs. 



Water per pound of combustible from and at 212 degrees, . 10.78 Ibs. 

 NOTE. The coal when fired contained 7 per cent, of moisture. 



The test on Boiler No. 23 shows the performance of a plant 

 of large boilers with one of the small grades of anthracite 

 coal. The boiler absorbed nearly the whole of the available 

 heat, and the temperature of the waste gases was reduced 

 below that of the water in the boiler. The evaporative result 

 secured is favorable, if account be taken of the kind of coal 

 and the moist condition in which it was fired. The quantity 

 of power developed is but little over one-half of the rated 

 power of the boilers. Capacity here is sacrificed for economy . 

 It is questionable whether the sacrifice is a wise one from a 

 commercial point of view, for nearly, if not quite, as good 

 economy can be obtained from boilers of smaller diameter, 

 containing a less number of tubes, and consequently a smaller 

 amount of heating surface. 



Boiler No. 24. 



Kind of boiler, Horizontal return tubular. 



Number used, ....... One. 



Horse-power ( basis 12 square feet ), . . Fifty-three. 



Kind of coal, ....... Anthracite broken. 



Age, Several years. 



Boiler No. 24 is an ordinary horizontal tubular boiler, 

 arranged and set in the same manner as the return tubular 

 boiler shown in the cuts of Boiler No. 1, with the exception 

 that the boiler under consideration has an overhanging front. 

 In this boiler the ratio of heating surface to grate surface is too 

 small to conform to the best practice. The boiler is set only 

 17 inches from the grate, and the space over the bridge wall is 

 contracted to a height of 4 inches. 



