BOILER No. 30. 137 



Dimensions of Boiler No. 30. 



Diameter of shell, 48 in. 



Length of shell between heads and length of tubes, . . 15 ft. 



Number of tubes 3 inches outside diameter, .... 49 



Area of heating surface, 640 sq. ft. 



Area of grate surface, ........ 13.5 sq. ft. 



Area through tubes, 2 sq. ft. 



Area through flue, ......... 2 sq. ft. 



Distance of grate to shell, . . . . . . 19 in. 



Distance of flat bridge to shell. 6 in. 



Ratio of heating surface to grate surface, . . . . 47 to 1 



Ratio of grate to tube area, 6.6 to 1 



Results of Tests, Boiler No. 30. 



Test No. 65. 

 Manner of start and stop, ....... Thin lire. 



Kind of run, Continuous. 



Duration, 7.6 hrs. 



Coal consumed, dry, 1,361 Ibs. 



Percentage of ash, 6.5 per cent. 



Water evaporated, 10,442 Ibs. 



Coal per hour, 177.9 Ibs. 



Coal per hour per square foot of grate, ..... 13.2 Ibs. 



Water per hour, 1,365 Ibs. 



Water per hour per square foot of heating surface, . . 2.1 Ibs. 



Horse-power developed, . . . . . . . 47.2 H. P. 



Boiler pressure, 75 Ibs. 



Temperature of feed water, . . . . . . .44 deg. 



Temperature of escaping gases, . . . . . 362 deg- 



Water per pound of coal, ....... 7.67 Ibs. 



AVater per pound of coal from and at 212 degrees, . .9.28 Ibs. 

 Water per pound of combustible from and at 212 degrees, . 9.91 Ibs. 



The test on Boiler No. 30 had for an object the determina- 

 tion of the general performance of the system of combustion 

 here employed. This system produced an almost smokeless 

 furnace. A very small quantity of light smoke appeared for 

 a short time after firing fresh coal, but it was almost colorless. 

 The high character of combustion, which the absence of smoke 

 seemed to indicate, secured no apparent benefit in the matter 

 of economy, for after allowing for the steam used by the 

 apparatus, the result is only 9.91 pounds of water from and at 

 212 degrees per pound of combustible, which is some 20 

 per cent, below the best practice. This inferior performance 

 cannot be attributed to any unfavorable conditions which the 



