BOILEE No. 40. 157 



Water per hour per square foot of heating surface, . . 3.6 Ibs. 



Horse-power developed, ....... 34.9 H. P. 



Boiler pressure, 82.2 Ibs. 



Temperature of feed-water, ...... 205.3 deg. 



Temperature of escaping gases, . . . . . 445 deg. 



Percentage of moisture in steam, 0.2 per cent. 



Water per pound of coal, ...... 8.39 Ibs. 



Water per pound of coal from and at 212 degrees, . . 8.76 Ibs. 



Water per pound of combustible from and at 212 degrees, 9.48 Ibs. 



The test on Boiler No. 39 shows the performance of a small 

 horizontal tubular boiler using Walston bituminous coal. 

 This boiler is not one from which to expect high results. 

 Being deficient in heating surface, a considerable loss occurs 

 from the heat of the waste gases, although the rate of combus- 

 tion is comparatively low. The result of this test is similar, 

 though less favorable, to that obtained on Boiler No. 34, 

 which used the same kind of coal. 



Boiler No. 4O. 



Kind of boiler, Horizontal return tubular. 



Number used, One. 



Horse-power ( basis 12 square feet ), . One hundred and five. 

 Kind of coal, . . . . . . George's Creek Cumberland. 



Age, ........ Several years. 



Boiler No. 40 is of the ordinary horizontal tubular type, 

 the general features of which, and the manner in which it is 

 set, are shown in the following cut. The setting is so arranged 

 that air is supplied above the fuel in two currents, one above 

 and one below the burning gases. The first supply comes 

 from the bridge wall, which is hollow, and it is discharged 

 through perforations in the rear face of the wall near the top. 

 The other current is supplied first to a second hollow wall 

 placed a short distance behind the bridge wall, and suspended, 

 so to speak, from the shell of the boiler, thereby causing the 

 products of combustion to pass beneath it. The air emerges 

 through perforations in the front face of this wall near the 

 bottom. 



