BOILER No. 41. 161 



Results of Tests, Boiler No. 41. 



Test No. 82. 

 Manner of start and stop, . . . . . . . Running. 



The results of the test on Boiler No. 41 are of interest in 

 showing the effect produced by the large extent of heating- 

 surface which the double-deck type of boiler contains. The 

 evaporation per pound of combustible from and at 212 degrees, 

 which is 11.81, is higher than that obtained from some hori- 

 zontal return tubular boilers of the ordinary kind ; but at the 

 same time, it is inferior to the best results from those boilers. 

 The rate of combustion, which is 7.96 pounds per square foot 

 of grate per hour, is probably too low for the best results on 

 a boiler having such a large amount of heating surface, and 

 the conditions of the tests are not in this respect the most 

 favorable. Taking into account simply the evaporative result, 

 it would appear that the increased surface over a well arranged 

 return tubular boiler of the ordinary type, produced no mate- 

 rial benefit. That the large area of heating surface was 

 efficient in absorbing the heat is seen in the low temperature 

 of the escaping gases, which was 322 degrees, this being below 

 the temperature of the water in the boiler. The steam which 

 the boiler generated contained 0.5 of one per cent, of moisture 

 as indicated by a barrel calorimeter. From this it appears 

 that the steam-heating surface in the upper shell was not suffi- 



