so 



BOILER TESTS. 



the wast 3 gases secured an increase in the evaporation of 6 

 per cent. This result corresponds quite closely to the effect of 

 lowering the temperature of the gases by means of a flue heater 

 in the case already noted, where a reduction of 107 degrees was 

 attended by an increase of 7 per cent, in the evaporation per 

 pound of coal . 



A similar comparison may be made on horizontal tubular 

 boilers using Cumberland coal. Table No. 5 gives a list of 

 these tests. 



TABLE No. 5. 



Common Horizontal Tubular Boilers, Cumberland Coal. 



Here the average flue temperature is 415 degrees. Nos. 

 5, 9, 19 and 31 have temperatures exceeding 415 degrees. The 

 average of these is 450 degrees, and the average evaporation is 

 11 .34 pounds. The remaining boilers have temperatures below 

 415 degrees, the average of which is 383 degrees, and these give 

 an average evaporation of 11.75 pounds. With 67 degrees less 

 temperature of the escaping gases, the evaporation is higher 

 by about 4 per cent. The difference here is less marked than 

 in the anthracite tests, both in range of temperature and in 

 economy, but it is in the same direction ; that is, the highest 

 evaporation is produced where the waste at the flue is the 

 least. 



