338 ECONOMY OF FUEL FOR STEAM MACHINERY. 



the cost of fuel being about .$2,675,000. These figures, representing 

 as they do about one-twelfth of the Railways of America, will give a 

 faint indication of the interest involved. 



In the above table we have abundant evidence of the effect which 

 the Fuel account has on the profits of Railways, as well as a clear in- 

 dication of the rate at which that account is increased as the forests 

 disappear in the vicinity of the lines. There is no question but the 

 consumption of wood in our Railways has been increased in their 

 earlier stages by an insufficient estimate of the consequences, and it 

 is doubtless true that less attention has been given to matters affect- 

 ing it than to any other particular branch of Railway Economy. In 

 England it has been more strictly attended to, but a wide difference 

 between Coke and Cordwood has in a great measure negatived the 

 value of the experience had in that country— the management of the 

 one being quite unsuitable to the other. The time is arrived however, 

 when the subject must receive greater attention, and some recent 

 articles in American periodicals devoted to Railroads evince a desire 

 on the part of our neighbours to enter upon a careful investigation of 

 the question. 



It is a received opinion among Mechanical Engineers, that only a 

 portion of the heat generated in the furnace is imparted to the water 

 in the boiler, and experiments have shown that this is owing to the 

 want of a sufficient admixture of oxygen to produce the perfect com- 

 bustion of the gases evolved from the burning fuel — hence the attempt 

 to introduce a great supply of air at different parts of the furnace. 



It was and is still with many a popular belief that the elongation of 

 the flues of a boiler would produce a corresponding economy in the 

 fuel — the flame escaping from the funnels of steamboats, and supposed 

 to be continuous from the furnace, being pointed to as evidence of the 

 escape of a large amount of unappropriated heat— it is now known that 

 this flame is produced by the ignition of the gases on the coming in 

 contact with the fresh air, and a careful set of experiments made by 

 Mr. Stephenson and later by Mr. Armstrong gave conclusive evidence 

 that no corresponding advantages are obtained from lengthened flues. 



A recent writer in the American Railway Times says : 



" There are two causes why all the heat which fuel may furnish is 

 not obtained. First, that the inflammable gases, evolved by the heat, 

 are not all consumed from a want of sufficient supply of oxygen, the 

 air drawn through the fire being only sufficient to decompose more 

 fuel than when decomposed it could burn, or supply with oxygen. 

 The thick smoke, that escapes from a chimney, when fresh fuel is 



