BOILER No. 40. 



159 



The test on Boiler No. 40 shows the performance of a hori- 

 zontal tubular boiler using Cumberland bituminous coal. The 

 conditions under which this test was made are all favorable to 

 the production of a high result, and the desired end was 

 realized in a notable degree, the evaporation being 12.47 

 pounds from and at 212 degrees per pound of combustible. 

 The ratio of heating surface to grate surface is ample, being 

 53.1 to 1, the coal was burned at a sufficient rate for good 

 combustion, a supply of air was introduced above the fuel in 

 such a way as to thoroughly mix with the burning gases, and the 

 heat wasted at the chimney w r as noticeably small for bitumi- 

 nous coal. The character of the combustion, as viewed 

 through a peek-hole at the back end of the boiler, was excel- 

 lent, and the appearance of the brick work at the rear part of 

 the setting indicated a high degree of heat. There was a 

 marked absence of dense black smoke discharged from the 

 chimney. 



Boiler No. 41. 



Kind of boiler, ' Double-deck, " hor. ret. tub. 



Number used One. 



Horse-power (basis 15 square feet), . Eighty-five. 



Kind of coal, ...... Bituminous Cumberland. 



Age, . . . . , . . . . One month. 



Boiler No. 41 is a so- 

 called " d o u b 1 e-d e c k " 

 boiler, arranged and set 

 in the manner shown in 

 the following cuts. It 

 differs from the ordinary 

 form of horizontal return 

 tubular boiler in having 

 two connecting shells, one 

 above the other. The 

 lower shell is completely 

 filled with tubes. The 

 upper shell is provided 

 simply to furnish steam 



