BOILER NO. 4. 



77 



Water per pound of coal from and at 212 degrees, . . 8.17 Ibs. 

 Water per pound of combustible from and at 212 degrees, . 9.66 Ibs. 



The interest in the test of Boiler No. 4, centers in the 

 arrangement of tubes noted, the kind of fuel burned, and the 

 use of the blower for increasing the draught. The only effect 

 of the reduced opening through the tubes, which is noticeable, 

 is the small amount of power developed, this being but little 

 over one-half of the rated power of the boilers. The fuel 

 contained a large proportion of anthracite screenings, which 

 produced a large percentage of ash. The heat was well 

 absorbed by the boilers, the escaping gases passing to the 

 chimney at about the temperature of the steam. The evapora- 

 tive result, considering the grade of fuel used, and taking 

 into account the ftict that the fuel contained about 4 per cent, 

 of moisture, compares favorably with that obtained with the 

 best grades of coal. 



The heat absorbed by the water in passing through the coil 

 ,in the flue, served to increase its temperature 13 degrees. The 

 water was fed by an injector, the temperature of its discharge, 

 or approximately that of the water entering the coil, being 155 

 degrees . 



Subsequent tests on this boiler, made at intervals of about 

 a year, and using different kinds of cheap-grade anthracite 

 coal, gave the following results : 



The amount of power developed by the boilers on the sup- 

 plementary tests was increased. On the last test the power 

 exceeded that of the rated horse power, and it may bo noted 



