202 



BOILEE TESTS. 



Area of grate surface, ........ 45 sq. ft. 



Area through tubes, ......... 4.1 sq. ft. 



Height of chimney, ...... 



Width of air spaces and metal bars in grates, 

 Distance of grate to tube sheet, 

 Ratio of water-heating surface to grate surface, 

 Ratio of steam-heating surface to grate surface, 

 Ratio of grate surface to tube area, 



Results of Tests, Boiler No. 57. 



Air 5-8 in. 



Test No. 118. 



90 ft. 

 metal 1-2 in. 

 2 ft. 8 in. 

 19.9 to 1 

 11.3 to 1 

 10.9 to 1 



Test No. 119. 



The tests on Boiler No. 57 show the performance of a verti- 

 cal tubular boiler under two rates of combustion, both of 

 which are comparatively high for the small proportion of heat- 

 ing surface to grate surface which is here found, viz., 19.9 to 

 1. As in all boilers of this class, the temperature of the 

 escaping gases is high, and there is a correspondingly low 

 economic result, There is a small reduction in the evapora- 

 tion produced by the high rate of combustion. It is notice- 

 able in the comparison of the two tests that it required double 

 the draught suction to increase the rate of combustion from 1 2 

 pounds to 14.2 mounds per square foot of grate per hour. 



