BOILER No. 22. 127 



Temperature of feed water, 206 deg. 



Temperature of escaping gases, ..... 350 deg. 



Water per pound of coal, 9-25 Ibs. 



Water per pound of coal from and at 212 degrees, . 9.62 Ibs. 



Water per pound of combustible from and at 212 degrees, 11.03 Ibs. 



The test on Boiler No. 22 shows the performance of a boiler 

 having a large proportion of heating surface, and using a 

 standard grade of anthracite coal. Although the amount of 

 power developed is much below the nominal capacity, a reason- 

 ably high rate of combustion is maintained, and the resulting 

 evaporation of 11.03 pounds of water from and at 212 degrees 

 per pound of combustible, is favorable when compared with 

 the most economical work. This test shows that a boiler 

 which is called upon to do light work can be made to give 

 economical results with a suitable adaptation of grate surface. 



Boiler No. 23. 



Kind of boiler, Horizontal return tubular. 



Number used, Three. 



Horse-power ( collective, basis 12 square feet), Four hundred and fifty. 



Kind of coal, ....... Anthracite Chestnut No. 2. 



Age, Three months. 



Boiler No. 23 embraces a plant of three horizontal tubular 

 boilers set in one battery of brick work, the general features 

 of which are shown in longitudinal section in the following 

 cut. The shells are 72 inches in diameter, and the proportion 

 of heating surface to grate surface is much larger than that 

 ordinarily found in small boilers, being 60 to 1. In this 

 respect the proportions are similar to those of the double deck 

 type of boiler. The brick setting is arranged for admitting a 

 supply of air at the bridge wall. Cast iron perforated globes 

 are provided for this purpose in the manner shown in the cut, 

 and these receive air from the outside through a pipe leading 

 to the rear end of the boiler. A steam jet is employed at the 

 end of the pipe to increase the quantity of air otherwise sup- 

 plied, and the steam mingles with the air thus introduced. 



