134 BOILER TESTS. 



The tests on Boilers No. 26 and No. 27 had for an object the 

 determination of the economy produced by admitting air above 

 the fuel, so far as could be determined by tests made on two 

 different sets of boilers. The tests were conducted simultan- 

 eously and the coal was used from the same pile, previously 

 mixed to insure uniformity. The registers in the fire-doors 

 were open in both sets of boilers. 



The results of the tests show that the admission of air 

 through the passages in the walls increased the evaporation 

 per pound of coal one per cent., and per pound of combustible 

 1J per cent. This occurred with Nova Scotia coal, which is 

 of an extremely gaseous and smoky character. 



The results of the tests as a whole show a rather low 

 economy when compared, for example, with the work of Cum- 

 berland coal ; but, as a partial explanation, it is seen that the 

 rate of combustion is large and the temperature of the escap- 

 ing gases is somewhat excessive. 



Boilers No. 28 and No. 29. 



Kind of boilers,. ..... Horizontal return tubular. 



Number used, each, One. 



Horse-power, each ( basis 12 sq. ft. ), . No. 28, 150; No. 29, 130. 

 Kind of coal, ...... Nova Scotia Culm. 



Age, ........ Three months. 



Boilers No. 28 and No. 29 are the two horizontal tubular boil- 

 ers previously referred to as Boiler No. 26. They are set in 

 one battery of brick work, and the style of the setting is that 

 shown in the cut of Boiler No. 6, with the exception that no 

 provision is made for admitting air above the fuel, and the 

 boilers are provided with flush fronts. The two boilers are 

 duplicates except as to size and number of tubes. In Boiler 

 No. 28 there are 100 3-inch tubes, and in Boiler No. 29 there 

 are 100 31 inch tubes. 



Dimensions, Boilers No. 28 and No. 29. 



Diameter of shell, each, 72 in. 



Length of shell between heads and length of tubes, each, . 16 ft. 



Boiler No. 28. Boiler No. 29. 



Number of tubes, 140 100 



Outside diameter of tubes, ... 3 in. 3.5 in. 



Area of heating surface, .... 1,799 sq. ft. 1,548 sq. ft 



