96 BOILEE TESTS. 



amounted to 3.6 per cent, based on coal, and 1.9 per cent, 

 based on combustible. Taking into account the slow rate of 

 combustion on Test No. 20, which was 4.7 pounds per square 

 foot of grate per hour, the performance of the boiler is excel- 

 lent. This is significant when the small diameter of the shell, 

 and the age of the boiler are taken into account. 



Boiler No. 1 1. 



Kind of boiler, . . . . . . Horizontal return tubular. 



Number used, One. 



Horse-power (basis 12 square feet), . . Fifty-three. 



Age, ........ Several years. 



Boiler No. 11 is of the ordinary horizontal return tubular 

 type. The arrangement of its setting is in all essential par- 

 ticulars like that shown in the cuts of Boiler No. 5, with the 

 exception that this boiler is provided with a flush front. For 

 the purpose of burning oil, as was done on Test No. 24, the 

 furnace was arranged as shown in longitudinal section in the 

 following cut. The oil burner consisted of a jet, having two 

 openings, one of which was supplied with oil, and the other 

 with steam. It was placed in the mouth of the furnace, and 

 the oil was brought to it by force of gravity. The grates were 

 covered with fire brick, and at the rear end of the furnace was 

 placed a mass of loose bricks, upon which the flames of the 

 burner were directed. The steam supplied to the burner was 

 superheated by passing it through pipes placed on the bottom 

 of the furnace, beneath the loose bricks referred to. The air 

 for combustion entered through the doorways of the furnace, 

 around the pipes leading to the burner, and the space sur- 

 rounding the pipes was left open. 



