12 BOILER TESTS. 



the commercial test, being of most interest to the manufacturer 

 or steam user, who must know how the coal is used which he 

 has to purchase. In conducting the engineering test the boiler 

 should be worked with a standard quality of fuel. It should 

 be clean on both the interior and the exterior surfaces. It should 

 be fired by a skillful fireman, who should use every exertion to 

 obtain the highest efficiency from the fuel. It should be worked 

 at such a capacity as will secure the most favorable result. The 

 boiler should be worked long enough in preparation for the en- 

 gineering test to heat itself and the material in which it is 

 encased to its normal working degree. The fire should then 

 be burned down to a low point and thoroughly cleaned, a thick- 

 ness of 2 or 3 inches of clean burning fuel being retained for a 

 foundation upon which the fire of the test is to be started. 

 With this thin fire, the thickness of which is estimated as a 

 basis for commencement, the test is begun. The boiler is then 

 operated in the manner determined upon, for at least 24 hours, 

 and the quality of coal burned and water evaporated is meas- 

 ured. At the close of the test the fire is again burned down 

 and cleaned, and this is done in such a manner that the condi- 

 tion and thickness of the bed of coal on the grate, as nearly as 

 can be estimated, is the same as it was at the commencement 

 of the test. For the commercial test the boiler should be oper- 

 ated in the manner customarily followed, and the measurement 

 of coal and water taken a sufficient number of days to give an 

 average indication of the performance. In factory work a test 

 of one week's duration is of suitable length. No change should 

 be made in the daily hours of running, the mode of firing, the 

 manner of treating the fires at night, nor in the general opera- 

 tion of the plant, the object being to include all these questions 

 in the determination of the main point at issue. 



If all tests could be made in accordance with these plans 

 nothing would be left to be desired. The relative efficiency of 

 different generators would be known at once. The manufac- 

 turer would have no complaint to make because the results of 

 the test do not correspond to those obtained under working 

 conditions. Unfortunately, no such uniformity of method can 



