.s/A' WILLIAM SIEMENS, F.R.S. 247 



moderate heat. The products of combustion pass away through 

 a similar set of flues at the other end of the furnace into the 

 regenerator chambers, C 1 , E l , and thence through the flues, M 1 , 

 N ' , and through the gas and air reversing valves, into the chimney 

 flue, 0. The waste heat is thus deposited in the upper courses 

 of open lire-brick work filling the chambers, C 1 , E 1 , so heating 

 them up, while the lower portion, and the chimney flue, are still 

 quite cool ; then after about an hour, the reversing valves, B 1 , 

 (through which the air and gas are admitted to the furnace) are 

 reversed, by means of the levers, P, and the air and gas enter 

 through those regenerator chambers, E 1 , C 1 , that have just been 

 heated by the waste products of combustion, and in passing up 

 through the open brickwork they become heated, and then on 

 meeting and entering into combustion in the furnace, D, D, they 

 produce a very high temperature, probably 500 Fahr. higher than 

 when admitted cold ; the waste heat from such higher temperature 

 of combustion heating up the previously cold regenerator chambers, 

 < . K, to a correspondingly higher heat. After about an hour's 

 work the reversing valves, B 1 , are again reversed, and the air and 

 gas enter the first pair of regenerator chambers, C, E, but which 

 are now very hot, and therefore the air and gas become very hot, 

 and enter the furnace in this state, meeting and entering into 

 combustion, and thus producing a still higher temperature, probably 

 500 higher still, and again heating the second pair of regenerator 

 chambers, C 1 , E 1 , so much higher, which enables them to again 

 heat the air and gas to a still higher degree, when the valves, B 1 , 

 are again reversed. Thus an accumulation of heat and an acces- 

 sion of temperature is obtained, step by step, so to speak, until 

 the furnace is as hot as is required ; for unless cold materials are 

 put in to be heated, and thus abstract heat, the temperature rises 

 as long as the furnace holds together, and the supply of gas and 

 air is continued. The heat is at the same time so thoroughly 

 abstracted from the products of combustion by the regenerators 

 that the chimney flue remains always quite cool. The command 

 of the temperature of the furnace and of the quality of the flame 

 is rendered complete by means of the gas and air regulating valves 

 shown at B in Fig. 2, and by the chimney damper. These are 

 adjusted to any required extent of opening by the notched rods, 

 Q , R, and S, (Fig. 2,) respectively, so that having the power of 



