122 BOILER TESTS. 



from the system. The quantity of smoke issuing from the 

 chimney with Cumberland coal was materially less than occurs 

 with the ordinary boiler setting, and this is an indication that 

 the system exerts a favorable effect in securing more perfect 

 combustion with bituminous coal. The test with anthracite 

 coal also gave a low result, a fact which points even more 

 plainly to the probability of excessive loss by radiation from 

 the furnace walls, as noted. Here the economy which ordi- 

 narily attends a high rate of combustion and low flue tempera- 

 ture was not realized. 



Boiler No. 19. 



Kind of boiler, . .. . . . . Horizontal return tubular. 



Number used, Four. 



Horse-power ( collective, basis 12 sq. feet ), Two hundred and seventy-five. 

 Kind of coal, Bituminous, Cumberland. 



Boiler No. 19 embraces four horizontal return tubular 

 boilers, set in one battery of brick work, the general features 

 of which are shown in the cuts of Boiler No. 5. Compared 

 with ordinary practice, the boiler has short tubes and large 

 grates, and, as a consequence, the ratio of heating surface to 

 grate surface is somewhat low, being 29.4 to 1. 



Dimensions of Boiler No. 19. 



Diameter of shell, GO in. 



Length between heads and length of tubes, . . . . 12 ft. 



Number of tubes ( collective ) 3 inches outside diameter, . 336 



Area of heating surface, ........ 3,534 sq. ft. 



Area of grate surface, ........ 120 sq. ft. 



Area through tubes, ......... 13.8 sq. ft. 



Area through flue, . .' 15.9 sq.ft. 



Height of chimney, 123 ft. 



Width of air spaces and metal bars in grates, Air 3-8 in., metal 7-16 in. 



Distance of grate to shell, . . . . . . . 24 in. 



Distance of flat bridge to shell, 9 in. 



Ratio of heating surface to grate surface, . . . . 29.4 to 1 



Ratio of grate surface to tube area, 8.7 to 1 



Results of Tests, Boiler No. 19. 



Test No. 54. 



Manner of start and stop, Thin fire. 



Kind of run, Continuous. 



Duration, . ... 10.2 hrs. 



