144 



BOIL EH TESTS. 



Dimensions of Boiler No. 33. 



Diameter of shell, 60 in. 



Length between heads and length of tubes, . . . . 15 ft. 



Number of tubes ( collective ) 3 inches outside diameter, . 132 



Area of heating surface, ....... 1,894 sq. ft. 



Area of grate surface, . . 50 sq. ft. 



Area through tubes, 5.4 sq. ft. 



Height of chimney, . . . . . . . . 110 sq. ft- 



Width of air spaces and metai bars in grates, Air 3-8 in., metal 7-10 in. 

 Ratio of heating surface to grate surface, .... 37.9 to 1 



Ratio of grate surface to tube opening, ..... 9.3 to 1 



Area of heating surface in flue heater, ..... 1,600 sq. ft. 



Results of Tests, Boiler No. 33. 



Test No. G9. | Test No. 70. 



NOTE. The coal when fired contained 2 1-2 per cent, of moisture. 



The tests on Boiler No. 33 were made to determine the 

 economy produced by a flue heater attached to ordinary hori- 

 zontal tubular boilers. They have a special interest in view 

 of the fact that the temperature of the escaping gases was not 

 above the point which is ordinarily considered favorable to 



