BOILER No. 42. 



163 



Area of grate surface, ..... 



Area through tubes, 



Area through chimney, 



Height of chimney, 



Ratio of water-heating surface to grate surface, 

 Ratio of steam-heating surface to grate surface, 

 Ratio of grate to tube area, .... 

 Ratio of grate to chimney area, 



90 sq. ft. 



17.3 sq. ft. 



11.1 sq. ft. 

 100 ft. 



65 to 1 

 3.3 to 1 

 5.2 to 1 

 8.1 to 1 



Results of Tests, Boiler No. 42, ( Average of three.) 



The tests on Boiler No. 42 were made in the same series as 

 those of Boiler No. 3, one set of boilers being used when the 

 other set was idle, and both being employed for the same work. 

 A comparison of Tests No. 5 and No. 83 may be made to show 

 the efficiency of the two types of boilers. Both tests were 

 made with coal from the same cargo. The double-deck boiler 

 secured a somewhat better result than the common boiler, the 

 figures per pound of combustible being 11.11 and 10.73. 

 The difference is 3.5 per cent. The reason for this result is 

 seen in the reduced quantity of waste heat. The temperature 



