176 



BOILER TESTS. 



Dimensions of Boiler No. 47. 



Diameter of shells ( 3 in each ) , 30 in. 



Length of shells, 30 ft. 



Area of heating surface, . ..... 1,320 sq. ft. 



Area of grate surface, 175 sq. ft. 



Area through flue, . ........ 10.5 sq. ft. 



Height of chimney, 120 ft. 



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



Distance of grate to shell, . 16 in. 



Ratio of heating surface to grate surface, . . . . 7.5 to 1 



Ratio of grate surface to flue area, . . . , . 16.7 to 1 



Results of Tests, Boiler No. 47. 



NOTE. The coal when fired contained 5 per cent, of moisture. On Test No. 94 the 

 ash-pit doors were partly closed. 



The tests on Boiler No. 47 exhibit the performance of plain 

 cylinder boilers using one of the small grades of anthracite 

 coal and working under two different rates of combustion. 

 One noticeable feature in the results is the high rate of evapo- 

 ration which occurred, being 6.9 pounds per square foot of 

 heating surface per hour in Test No. 93, and 5.5 pounds in 

 Test No. 94. Another is the high temperature of the escaping 

 gases, which was 650 degrees in the first test, and 567 degrees 

 in the second test. Both of these are due to the rela- 

 tively small amount of the heating surface. In view of the 



