156 BOILER TESTS. 



left the drum, and probably 50 degrees at the point of leaving 

 the boiler. The general results of the test are inferior to the 

 best boiler practice. The evaporation per pound of coal, 

 however, is about the same as vertical tubular boilers give, 

 when producing superheated steam at the same temperature. 



Boiler No. 39. 

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



Number used, . . . . . . One. 



Horse-power ( basis 12 square feet ), . . Twenty-seven. 

 Kind of coal, ..... . Bituminous Walston. 



Age, ........ Several years. 



Boiler No. 39 is an ordinary horizontal boiler set in brick 

 work in the general manner shown in the cut of Boiler No. 

 10, differing, however, from that boiler in being provided 

 with an overhanging front, the gases from which pass directly 

 to the chimney. This boiler has a small shell, short tubes, 

 and a low proportion of heating surface to grate surface. 

 Dimensions of Boiler No. 39. 



Diameter of shell, ......... 42 in. 



Length between heads and length of tubes, . . . 10 ft. 



Number of tubes, 3 inches outside diameter, .... 30 



Area of heating surface, ........ 322 sq. ft. 



Area of grate surface, .... ... 14.4 sq. ft. 



Area through tubes, ...... 1.5 sq.ft. 



Area through flue, ......... '2.2 sq. ft. 



Height of chimney ....... . . . 5G ft. 



Width of air spaces and metal bars in grates, Air 5-1C in., metal 11-16 in. 



Distance of grate to shell, ....... 21 in. 



Distance of flat bridge to shell, . ..... 8 in. 



Ratio of heating surface to grate surface, . . . . 22.3 to 1 



Ratio of grate surface to tube area, . . . . . 9.8 to 1 



Results of Test, Boiler No. 39. 



Test No. 80. 

 wtth preliminwy 



Manner of start and stop, . . . . 



Kind of run, .......... Continuous. 



Duration, ... ...... 8.3 hrs. 



Coal consumed, dry ( including wood equivalent ), . 1,134 Ibs. 



Percentage of ash, ........ 7.G per cent. 



Water evaporated, ........ 9,519 Ibs. 



Coal per hour ..... .... 137.4 Ibs. 



Coal per hour per square foot of grate, .... 9.52 Ibs. 



Water per hour, ........ 1,153.3 Ibs. 



