148 



BOILER TESTS. 



Results of Tests, Boiler No. 35. 



NOTE. The Cumberland coal when fired contained 3 per cent, of moisture. 



The tests on Boiler No. 35 were made to determine the gen- 

 eral economy of the boiler with Cumberland and anthracite 

 coal. The test with Cumberland coal was made under condi- 

 tions of a slow rate of combustion, and that with anthracite 

 coal under a much higher rate, so that the relative performance 

 of the two fuels cannot fairly be compared. The boiler has 

 an ample area of heating surface, the proportion of which to 

 grate surface is 47.4 to 1 ; but this does not appear to have 

 been sufficient to absorb the whole of the available heat which 

 was generated in the case of the test with anthracite coal, the 

 temperature of the escaping gases being 428 degrees. The 

 efficiency of the surfaces had probably become deteriorated by 

 deposits of scale, and this furnishes a reason for the somewhat 

 unfavorable evaporative result which was produced. The 

 result obtained on the test with Cumberland coal is equally 

 unfavorable, but here the rate of combustion was too low to 

 secure the highest degree of economy. 



