BOILEE No. 56. 201 



Draught suction 0.08 in. 



Water per pound of coal, 6.96 Ibs. 



Water per pound of coal from and at 212 degrees, . 7.86 Ibs. 



Water per pound of combustible from and at 212 degrees, 8.91 Ibs. 



The test on Boiler No. 56 shows the performance of a verti- 

 cal boiler, which was deficient in heating surface, when using 

 one of the small grades of anthracite coal. The rate of com- 

 bustion is low, and there is consequently a small amount of 

 power developed. The power is nearly 40 per cent, below 

 the nominal capacity. In spite of this low rate the tempera- 

 ture of the escaping gases is high, being 468 degrees, and the 

 economic result is inferior, not only to the best class of 

 boilers, but also to the best performance of this particular 

 class. In this boiler, as in other vertical boilers set in brick 

 work, there is a large exterior surface exposed to the air. 

 This surface not only causes radiation, but owing to the un- 

 stable condition of brick-work which has had a long period of 

 service, it provides many avenues for the entrance of air both 

 to the furnace and to the flue space. The effect of unneces- 

 sary admission of air is to reduce the efficiency of the fuel and 

 to lower the temperature of the gases. The last-named effect 

 causes the apparent indication of waste heat to be much less 

 than the real quantity. 



Boiler No. 57. 



Kind of boiler, Vertical tubular ( rolling pin ) . 



Number used, One. 



Horse-power ( basis 10 square feet ), . One hundred and forty. 



Kind of coal, Anthracite Lackawanna, egg. 



Age, Several years. 



Boiler No. 57 is a vertical boiler of the rolling pin type, 

 having the general features shown in the cut of Boiler No. 51, 

 Dimensions of Boiler No. 57. 



Diameter of main shell, 90 in. 



Diameter of drum and water leg, . . . . . . 31 in. 



Length of main shell and tubes, 10 ft. 



Number of tubes, 2 inches outside diameter, .... 248 



Area of water-heating surface, 897 sq. ft. 



Area of steam-heating surface, 505 sq. ft. 



Area of total heating surface, 1,402 sq. ft. 



