14 ANNUAL OF SCIENTIFIC DISCOVERY. 



locality. Within the last two years the Siemens furnace has been 

 adopted in all the larger Bessemer steel works in England. In 

 France, it is gaining ground with equal rapidity, and there are 

 now twenty furnaces in course of erection under Mr. Siemens' own 

 superintendence at the Creusot Works. 



There are two distinct principles embodied in the Siemens fur- 

 nace, namely, the application of gaseous fuel, and the regeneration 

 of heat by means of piles of bricks alternately passed over by 

 the waste gases and by the gases entering the furnace before their 

 combustion. The gas-producer is a brick chamber about 6 feet 

 wide by 12 feet long, with its front wall inclined at an angle of 

 45 to 60, according to the nature of the fuel used. The inclined 

 plane is solid about half way down, and below this it is con- 

 structed as a grate with horizontal bars. The openings for intro- 

 ducing the coal into the gas-producer are on the top or roof of 

 this chamber, and the air which enters through the grate effects 

 the combustion of the coal at the lowest points of the chamber. 

 The products of this combustion rise, and are decomposed by the 

 superposed strata ; they are, moreover, mixed with a quantity of 

 steam which is drawn in through the grate from a constant supply 

 of water maintained underneath the latter. The steam in con- 

 tact with the incandescent coal also decomposes and produces 

 hydrogen and carbonic oxide gas, which are mixed with the 

 gases produced by the coal direct. The whole volume of these 

 gases is then conducted to the furnace itself by means of wrought- 

 iron pipes. The gases enter one of the regenerators. The re- 

 generators are chambers packed with fire-bricks, which are 

 built up in walls with interstices and air-spaces between them, 

 allowing of a free passage of gas around each single brick. 

 Each regenerator consists of two adjoining chambers of this kind, 

 with air-passages parallel to each other, one passage destined for 

 the gaseous fuel, and the other for the supply of atmospheric air 

 required for combustion. Each furnace has two such regen- 

 erators, and a set of valves is provided in the main passages, or 

 flues, which permit of directing the gases from the producer to 

 the bottom of either of the two regenerators. The gases, after 

 passing one regenerator, arrive at the furnace, where they are 

 mixed with the air drawn in at the same time, and produce a 

 flame of great heat and intensity within the body of the furnace 

 itself. They then pass, after combustion, into the second regen- 

 erator, which forms a set of down flues for the waste gases, and 

 ultimately leads them off into a common chimney. On their way 

 from the furnace to the chimney, the heated products of combus- 

 tion raise the temperature of the fire-bricks, over which they pass, 

 to a veiy high degree, and the gases are cooled more and more 

 the further they proceed through the regenerator. After a cer- 

 tain time the fire-bricks close to the furnace obtain a temperature 

 almost equal to that of the furnace itself, and a gradually dimin- 

 ishing temperature is arrived at in the bricks of the regenerator 

 proportionate to their distance from the furnace. At this moment 

 the attendant, by reversing the different valves of the furnace, 

 opens the heated regenerator for the entrance of the gaseous 



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