246 THE SCIENTIFIC PAPERS OP 



J, (Fig. 1), from which it passes down either directly to the 

 furnace, or into an underground brick flue. 



The gas rising from the producer at a temperature of about 

 1000 Fahr., is cooled as it passes along the overhead tube, and 

 the descending column is consequently denser and heavier than 

 the ascending column of the same length, and continually over- 

 balances it. The system forms, in fact, a syphon in which the 

 two limbs are of equal length, but the one is filled with a 

 heavier gaseous fluid than the other. 



In erecting a number of gas-producers and furnaces I generally 

 prefer to group the producers together, leading the gas from 

 all into one main flue, from which the several furnaces draw 

 their supplies. 



The puddling furnace, proper, is shown in Plate 41, Fig. 2, 

 and Plate 42, Figs. 3 and 4. 



Fig. 2 is a sectional plan, and Fig. 3 is a front elevation of the 

 furnace, showing the gas reversing valve and flues in section. 



Fig. 4, is a longitudinal section. 



The peculiarity of the regenerative gas furnace, as applied either 

 to puddling, or to any other process in which a high heat is 

 required, consists in the utilization in the furnace of nearly the 

 whole of the heat of combustion of the fuel, by heating the 

 entering gas and air by means of the waste heat of the products 

 of combustion, after they have left the furnace, and are of no 

 further use for the operation being carried on. The waste heat is, 

 so to speak, intercepted on its passage to the chimney, by means 

 of masses of fire-brick stacked in an open or loose manner in 

 certain chambers, called " Regenerator chambers," C, E, E 1 , C l , 

 (Fig. 3). 



On first lighting the furnace the gas pr.sses in through the gas 

 regulating valve, B, (Fig. 2), and the gas reversing valve, B 1 , 

 and is led into the flue, M, and thence into the bottom of the 

 regenerator chamber, C, (Fig. 3) ; while the air enters through 

 a corresponding " air reversing valve," behind the valve B 1 , and 

 passes thence through the flue, N, into the regenerator chamber, 

 E. The currents of gas and air, both quite cold, rise separately 

 through the regenerator chambers, C and E, and pass up through 

 the gas and air flues respectively, into the furnace above, 

 where they meet and are lighted, burning and producing a 



