BOILEE No. 38. 155 



Dimensions of Boiler No. 38. 



Diameter of shell, 42 in. 



Length between heads and length of tubes, . . . 10 ft. 

 Number of tubes, 2 inches outside diameter, below water-line, 67 

 Number of tubes, 2 inches outside diameter, above water-line, 68 



Area of water-heating surface, 369.3 sq. ft. 



Area of steam-heating surface, 318.8 sq. ft. 



Area of grate surface, . . . . . . . 9.2 sq. ft. 



Tube area below water-line, . . . . . 1.1 sq. ft. 



Flue area, 2.2 sq. ft. 



Height of chimney, . 30 ft. 



Width of air spaces and metal bars in grates, . . . 5-8 in. 



Katio of water-heating surface to grate surface, . . 40.3 to 1 



Ratio of steam-heating surface to grate surface, . . 36.6 to 1 



Ratio of grate surface to tube area below water-line, . 8.2 to 1 



Eesults of Tests, Boiler No. 38. 



Test No. 79. 

 Manner of start and stop, . . . . | Ordmary^ with preliminary 



Kind of run, Continuous. 



Duration, 8 hrs. 



Coal consumed, (including wood equivalent ), . . 1,453 Ibs. 

 Percentage of ash, ........ 9.5 per cent. 



Water evaporated, 10,341 Ibs. 



Coal per hour, 181.5 Ibs. 



Coal per hour per square foot of grate, .... 20 Ibs. 



Water per hour, 1,291.8 Ibs. 



Water per hour per square foot of water-heating surface, 3.5 Ibs. 



Horse-power developed, 45.5 H. P. 



Boiler pressure, ........ 66 Ibs. 



Temperature of -feed-water, 36 deg 



Temperature of escaping gases entering upper tubes, . 558 deg. 



Temperature of escaping gases leaving upper tubes, . 394 deg. 



Number of degrees of super-heating, .... 30 deg. 



Water per pound of coal, ...... 7.12 Ibs. 



Water per pound of coal from and at 212 degrees, . 8.64 Ibs. 



Water per pound of combustible from and at 212 degrees, 9.55 Ibs. 



The test on Boiler No. 38 shows the performance of a super- 

 heating boiler using anthracite coal. The chief interest in the 

 test lies in the effect produced by the steam-heating surface as 

 here arranged. The temperature of the gases in passing over 

 this surface was reduced from 558 degrees, the temperature 

 on entering, to 394 degrees. This served to dry the moisture 

 in the steam and superheat it 30 degrees at the point where it 



