230 



BOILEE TESTS. 



Little effect seems to have been produced by the steam heat- 

 ing surface, so far as it could be observed from the ther- 

 mometer immersed in the steam. 



Boiler No. TO. 



Kind of boiler, 



Number used, 



Horse-power (basis 12 sq. ft. ), . 



Kind of coal, 



Age, 



Boiler No. 70 is a water tube boiler having the general 

 features shown in the cut of Boiler No. 66. 



Water tube. 



One. 



One hundred and thirty-six. 



Bituminous Cambria. 



Eight years. 



Dimensions of Boiler No. 70. 



Number of tubes 4 inches outside diameter, . . . .80 



Length of tubes, 18 ft. 



Diameter of drums (two), . . . . . . . 30 in. 



Mean length of drums, 7 ft. 6 in. 



Area of heating surface, . . . . . . 1,638 sq.ft. 



Area of grate surface, 36 sq. ft. 



Width of air spaces and metal bars in grates, . . . 3-4 in. 

 Ratio of heating surface to grate surface, . . . . 45.5 to 1 

 Results of Tests. Boiler No. 70. 



Test No. 136 

 Manner of start and stop and kind of run, . . . Ordinary. 



Duration, 10.6 hrs. 



Coal consumed, dry (including wood equivalent ), . 6,185 Ibs. 



Percentage of ash, ......... 10.5 per cent. 



Water evaporated, 52,206 Ibs. 



Coal per hour, . . 608.9 Ibs. 



Coal per hour per square foot of grate, .... 16.89 Ibs. 



Water per hour, 4,946 Ibs. 



Water per hour per square foot of heating surface, . .3 Ibs. 



Horse-power developed, . 166.3 H. P. 



Boiler pressure, ......... 62.4 Ibs. 



Temperature of feed-water, 88.3 deg. 



Temperature of escaping gases, 471 deg. 



Draught suction, . . . . . . . . .0.2 in. 



Percentage of moisture in steam, 0.42 per cent. 



Water per pound of coal 8.44 Ibs. 



Water per pound of coal from and at 212 degrees, . . . 9.78 Ibs. 

 Water per pound of combustible from and at 212 degrees, 10.93 Ibs. 

 NOTE. The coal when fired contained 3.7 per cent, of moisture. 



