228 



BOILEE TESTS. 



temperature of the gases was reduced to 402 degrees, which, 

 under the circumstances, is most favorable to economy. 

 Furthermore , the new condition of the setting prevented the 

 introduction of unneeded air, which seems to have been one of 

 the main causes of the unfavorable results of the later tests. 



Boiler No. 69. 



Kind of boiler, . . 



Number used, 



Horse-power ( basis 12 square feet), 



Kind of coal, . . . . . . 



Age, . 



Water tube. 



One. 



Eighty. 



f Anthracite Lackawanna Chest- 

 \ nut No. 2. 



Three months. 



Boiler No. 69 is a water tube boiler, having the general 

 features shown in longitudinal section in the following cut. 

 It is provided at the top with three drums, 14 inches in 

 diameter, connected at the ends to the tubes below, and these 

 are wholly enclosed in the chamber formed by the brick 

 setting. The water line is carried to about the central point 

 of the drums, and the exterior surface above it furnishes a 

 small amount of steam heating surface. 



BOILER No. 69, LONGITUDINAL SECTION. 



