PROCEEDINGS OF THE POLYTECHNIC ASSOCIATION. 375 



manufacture. Now, the fact that in our very best regulated plans of 

 using* fuel we seldom realize more than one-twentieth of its actual value, 

 and in our ordinary operations not one-hundredth, shows how much improve- 

 ment is to be desired and to be striven for. These truths are well known, 

 and the question of fuel is discussed everywhere. In our club it is quite 

 threadbare, so that I need to make the explanation that I introduced it 

 only to bring out opinions on the new system of using fuel, illustrated by 

 Siemens' regenerator furnace, and the new material for fuel, rock oil. 

 (A brief description of Siemens' invention was here given.) In this fur- 

 nace it is to be observed that the coal produces no more heat than in other 

 furnaces where the combustion is equally perfect. Also, by the use of 

 water and the water gases (hydrogen and carbonic oxyd), the total heat is 

 not increased; the coal is, in effect, partly converted into water gases, 

 which burn and give the heat which otherwise would come directly from 

 the coal. Coal and water are fed at the stoking place, and the solid coal 

 and liquid water expand into the combustible gases — carburetted hydrogen, 

 hydrogen and carbonic oxyd — and pass on to the spot where they are to be 

 completely burnt. The advantage of this transportation of the coal lies 

 in the fact that the burning of the gaseous products can be more easily 

 controlled, and the heat can be more directly and completely carried to the 

 point where it is useful. The novelty of Siemens' furnace is, however, his 

 regenerator, b}"- which the heat from the otherwise waste products is pre- 

 served and brought again to the working point. It is also evident that 

 this waste heat of the regenerator is so added to that of the gaseous 

 fuel that the intensity of the working heat is greatly increased, a fact of 

 great consequence in many industrial operations. 



With reference to rock oil I will only remark that although its cost by 

 weight must always be much greater than that of coal, yet for many pur- 

 poses it will be much cheaper, for the reason that the heat it gives can be 

 more completely utilized. Although it costs fifty times more than coal, yet 

 if it does fifty-one times more work, it is plain that it is cheaper. Later iu 

 the discussion I will present some new methods of burning it. 



Mr. Fisher. — I have made here on the blackboard a rough sketch of the 

 apparatus invented by Mr. Clark, for burning the smoke in locomotives in 

 which bituminous coal is used. A number of small openings, usually four- 

 teen, are made in the furnace, and small jets of steam are blown througli 

 these openings, carrying currents of air with them. This air mingles with 

 the gaseous products of combustion, and burns them. It was found that 

 this plan worked very well on locomotives where steam is usually carried 

 at a pressure of one hundred lbs. or more to the inch, but when the attempt 

 was made to apply it to marine engines where the pressure is only thirty 

 lbs. to the inch it did not answer so well; there was too much steam in 

 proportion to the air. Even in the locomotive engine the steam must tend 

 to reduce the temperature, as it enters the fire box at some 300°, while the 

 burning gases are not less, probably, than 2,500°. 



It has occurred to me that the vapor of petroleum might be blown into 

 the furnace in place of steam, and thus the heat might be considerably 

 increased. A separate boiler might be used for evaporating the petroleum, 

 and the jets arranged in the manner adopted by Mr. Clark. Where petro- 



