1 86 APPENDIX. 



the start, a correction should be made by computation, and 

 not by operating the pump after the test is completed. 



XI. Uniformity of Conditions. In all standard trials the 

 conditions should be maintained uniformly constant. Ar- 

 rangements should be made to dispose of the steam so that 

 the rate of evaporation may be kept the same from beginning 

 to end. This may be accomplished in a single boiler by 

 carrying the steam through a waste steam-pipe, the discharge 

 from which can be regulated as desired. In a battery of 

 boilers in which only one is tested the draught can be regu- 

 lated on the remaining boilers, leaving the test-boiler to work 

 under a constant rate of production. 



Uniformity of conditions should prevail as to the pressure 

 of steam, the height of water, the rate of evaporation, the 

 thickness of fire, the times of firing and quantity of coal fired 

 at one time, and as to the intervals between the times of 

 cleaning the fires. 



XII. Keeping the Records.- Take note of every event 

 connected with the progress of the trial, however unimpor- 

 tant it may appear. Record the time of every occurrence 

 and the time of taking every weight and every observation. 



The coal should be weighed and delivered to the fireman 

 in equal proportions, each sufficient for not more than one 

 hour's run, and a fresh portion should not be delivered until 

 the previous one has all been fired. The time required to 

 consume each portion should be noted, the time being re- 

 corded at the instant of firing the last of each portion. It is 

 desirable that at the same time the amount of water fed into 

 the boiler should be accurately noted and recorded, including 

 the height of the water in the boiler, and the average pressure 

 of steam and temperature of feed during the time. By thus 

 recording the amount of water evaporated by successive por- 

 tions of coal, the test may be divided into several periods if 

 desired, and the degree of uniformity of combustion, evapo- 

 ration, and economy analyzed for each period. In addition 



