70 BOILER TESTS. 



to a single 80 horse-power boiler of the horizontal tubular type, 

 some 75 feet distant. A test on these, during which all the 

 steam generated by the boiler passed through the superheater, 

 showed that 473 pounds of anthracite coal were required to 

 superheat 23,609 pounds of steam 228 degrees. The quantity 

 of coal consumed in the boiler furnace, was 2657 pounds, and 

 the rate of combustion 6.3 pounds per square foot of grate per 

 hour. The rate of combustion in the superheater was 4.8 

 pounds per square foot of grate per hour. The evaporation of 

 the boiler per pound of combustible from and at 212 degrees, 

 was 10.95 pounds; temperature of feed water, 215 degrees; 

 temperature of gases, 290 degrees; temperature of gases 

 leaving superheater, 394 degrees. In this case a superheating 

 of 228 degrees required the consumption of an additional 17.8 

 per cent, of coal in the independent furnace. 



The quantity of coal required for superheating, in all these 

 cases, is greater than that which would be expected if account 

 be taken simply of the additional heat of the steam. The dif- 

 ference, however, is not more than can fairly be attributed to a 

 slightly moist condition of the steam generated by the boiler 

 and to loss of heat produced by radiation from the pipe leading 

 from the boiler to the superheater, and by radiation from the 

 superheater itself. 



Boiler No. 2. 



Kind of boiler, Horizontal return tubular- 

 Number used, ....... Two. 



Horse-power ( collective, basis 12 sq. ft. ), . One hundred and three. 



Kind of coal, Bituminous, Cumberland. 



Age, ......... Several years. 



Boiler No. 2 consists of two 48 inch boilers, set over a fur- 

 nace common to both, in the manner shown in the following 

 cuts. The draught of the chimney, which is deficient, is aided 

 by a blower, which discharges the air beneath the grate. 

 Except in these particulars, the boiler, as arranged for the first 

 test, calls for no special comment. The dotted lines shown in 

 the longitudinal section represent heating surfaces, which were 

 introduced after the first test was made. These surfaces con- 



