BOILER No. 8. 



87 



Dimensions of Boiler No. 8. 



Diameter of shell, 



Length between heads and length of tubes, 

 Number of tubes 4 inches outside diameter, . 

 Area of heating surface, . . 

 Area of grate surface, . . . . 



72 



15 

 70 



1,189 

 36 



in. 

 ft. 



sq. 

 sq. 



Area through tubes, 5.3 sq, 



Area through chimney, . . 

 Height of chimney, . . 



Width of air spaces ana metal bars in grates, 

 Ratio of heating surface to grate surface^ 

 Ratio of grate surface to tube area, 



Air 7-16 in. 



5.9 sq. ft. 

 60 ft. 

 metal 3-8 in. 

 33 to 1 



6.7 to 1 



Results of Tests. Boiler No. 8. 



NOTE. The coal was wet before firing, and the weight was increased by this means 

 about 6 per cent. 



The tests on Boiler No. 8 were made to determine the com- 

 parative economy of forced draught with heated air, and natural 

 draught, where the fuel was largely composed of anthracite 

 screenings, together with the general result produced by the 

 use of a detached furnace. An exact comparison cannot be 

 made between the two tests, owing to the different conditions 

 in respect to capacity, 130 horse-power being developed with 



