STEAM BOILER TESTS — ROBB. 11 



•govern the combustion of fuels, will doubtless be admitted by 

 many persons who have observed locomotive firemen or others 

 who are compelled to get a high rate of steam production. It is, 

 of course, impossible to transfer all the heat produced in combus- 

 tion to the water in a generator, because the gases cannot be 

 reduced below the temperature of the water or steam within the 

 generator, and a certain temperature above the atmosphere is 

 necessary to produce draught in the chimney; but it is quite pos- 

 sible to so proportion the grate surface to the heating surface of 

 the boiler that the gases will be reduced to a certain minimum 

 temperature and maintained at that temperature during a test. 

 The temperature may be indicated by a pyrometer' or high regis- 

 tering thermometer at the base of the chimney, and the rate of 

 ilow of the gases may be ascertained by the use of a draught- 

 gauge. Frequently an attempt is made to analyse the wa«te 

 gases. This gives an uncertain result on account of the difficulty 

 of getting representative samples of the gases; but, from observa- 

 tion and examination of many tests, the writer believes it unim- 

 portant, if the s'oking and air regulation receive proper attention. 

 The surface of the grate should be so proportioned to the heat- 

 ing, or heat absorbing, surface of the generator that the gases 

 will, when they reach the uptake, be reduced to, say, 400 Far. 

 Skilful firing and air regulation will produce practically perfect 

 combustion and uniform temperature. 



Steam boiler tests, although attended with some difficulty, are 

 quite within the reach of ordinary consumers, and deserve to be 

 better understood and used more than they are. In addition to 

 their value as a method of determining the heating properties of 

 fuel, they furnish the bestpos'^ible means of ascertaining the con- 

 dition and efficiency of the generator and of checking, and if 

 necessary correcting, waste on the part of the stoker. It is 

 desirable that such tests should be made frequently, because 

 steam boilers are very liable to deteriorate and become wasteful, 

 €spi'cially when set in brick, through the cracking of the brick 

 walls, as well as by the coating of heating surfaces with scale or 

 other deposit on the inner, and soot or ashes on the outer, sur- 

 faces. It is quite practicable for steam users to have tests made 



