208 BOILER TESTS. 



low, which could not be otherwise with the high flue tempera- 

 ture which existed, viz., 645 degrees. 



Considering the results of test No. 121 as applied to the 

 plant as a whole, the evaporation per pound of combustible 

 from and at 212 becomes 11.54 pounds. Allowing for the 

 superheating, which amounted to 52 degrees, the result is 

 equivalent to 11.84 pounds of water evaporated. This is not 

 far below the best results commonly obtained from well pro- 

 portioned horizontal tubular boilers not provided with a flue 

 heater. 



Boiler No. 6O. 



Kind of boiler, . Vertical tubular ( fire box ) . 



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



Horse-power ( collective, basis 13 sq. ft. ), Two hundred and sixty. 



Kind of coal, . George's Creek Cumberland. 



Age, . . . . . . . 4 Sixteen mouths. 



Dimensions of Boiler No. 60. 



Diameter of shell, . 60 in. 



Height between heads and length of tubes, .... 15 ft. 



Number of tubes ( collective ), 2- inches outside diameter, . 360 

 Diameter of fire box and grate, . . . . . . 6 ft. 



Distance of grate to lower tube sheet, . . . . . 3 ft. 6 in. 



Width of air spaces and metal bars in grates, Air 1-2 in., metal 5-8 in. 



Area of water-heating surface, ...... 2,521 sq. ft. 



Area of steam-heating surface, 880 sq. ft. 



Area of total heating surface, 3,401 sq. ft. 



Area of grate surface, ........ 56.7 sq. ft. 



Area through tubes, ......... 8 sq. ft. 



Ratio of water-heating surface to grate surface, . . . 44.5 to 1 

 Ratio of steam-heating surface to grate surface, . . . 15.7 to 1 

 Ratio of total heating surface to grate surface, . . . 60.2 to 1 

 Ratio of grate surface to tube area, 7.1 to 1 



