BOILER No. 52. 



189 



Area through tubes, ' 0.7 sq. ft. 



Area through stack, 0.78sq. ft. 



Height of stack, 52 ft. 



Ratio of total heating surface to grate surface, . . . 33.5 to 1 



Ratio of grate surface to tube area, 8.7 to 1 



Results of Tests, Boiler No. 52. 



I Test No. 104, | Test No. 105. 



The tests on Boiler No. 52 were made with two rates of 

 combustion, viz., 15 pounds and 9.1 pounds per square foot of 

 grate per hour. The high rate of combustion in Test No. 104 

 is noticeable, considering the low height of the stack, which 

 was 52 feet, and this was not the maximum, as the damper was 

 partially closed. The arrangement of tubes in the vertical 

 type of boiler, with stack directly above, is favorable for the 

 production of a large capacity with a feeble draught, and this 

 fact is here exemplified. The results of these tests furnish 

 evidence that the use of a fire box in vertical boilers is advan- 

 tageous. Comparing Test No. 105 on this boiler, with Test 

 No. 102 made on vertical boiler No. 51 which is set in brick 

 work, there is a noticeable improvement in favor of the fire- 

 box boiler, the two quantities being respectively 10.51 pounds 



