182 BOILEE TESTS. 



Dimensions of Boiler No. 50. 

 Diameter of each shell, . . . . . . . . 84 in. 



Length of shell, . . . 28 ft. 



Area of heating surface, ....... 5,628 sq. ft. 



Area of grate surface, 217.6 sq. ft. 



Area through flue, ......... 60 sq. ft. 



Width of air spaces and metal bars in grates, Air 1 in., metal 3-8 in. 



Height of chimney, , 230 ft. 



Ratio of heating surface to grate surface, . . . . 25.9 to 1 

 Ratio of grate surface to flue area, 3.6 to 1 



Results of Test, Boiler No. 50. 



Test No. loo. 

 Manner of start and stop, ..... Running with thin tire. 



Kind of run, Continuous. 



Duration, . ... . . . . . . . 12.7 hrs. 



Coal consumed, dry, 47,638 Ibs. 



Percentage of ash, 6.0 per cent. 



Water evaporated, 370,448 Ibs. 



Coal per hour, 3,756.9 Ibs. 



Coal per hour per square foot of grate, . . . . 17.3 Ibs. 



Water per hour, . 29,210.3 Ibs. 



Water per hour per square foot of heating surface, . 5.2 Ibs. 



Horse-power developed, 1,024.3 II. P. 



Boiler pressure, ........ 51.2 Ibs. 



Temperature of feed-water, ...... 36.7 deg. 



Temperature of escaping gases, 533 deg. 



Draught suction, ........ 0.64 in. 



Percentage of moisture in steam, ..... 7 per cent. 



Water per pound of coal, 7.78 Ibs. 



Water per pound of coal from and at 212 degrees, . 9.40 Ibs. 



Water per pound of combustible from and at 212 degrees, . 10.00 Ibs. 



The test on Boiler No. 50 shows the performance of an 

 internally fired boiler of special type, worked at a high rate of 

 capacity. The rate of combustion was 17.3 pounds of coal 

 per square foot of grate per hour, and this was obtained by 

 the employment of a draught which reached the excessive 

 pressure of 0.64 inches. Owing to the small amount of heat- 

 ing surface, the rate of evaporation was exceedingly high, 

 being 5.2 pounds per square foot of heating surface per hour. 

 This rate, however, was insufficient to work the boilers to 

 their normal capacity, as based on the builders' rating of the 

 power. The temperature of the escaping gases is above the 

 standard of good economy, though not so high as might be 



