98 THE SCIENTIFIC PAPERS OF 



into the water ; the rise of temperature produced in the water 

 showed the degree of heat upon a thermometer scale graduated 

 in the proper proportion, and the results thus obtained must 

 certainly be correct within 10 or 15" Fahr. Rather larger yields 

 were obtained with the regenerative puddling furnace, but it had 

 not been long enough at work yet to give any definite results. 

 The puddling furnaces at work in Germany however showed at 

 least 4 or 5 per cent, increase in the yield of iron, and this result 

 was indeed to be expected, because the new furnace was free from 

 the cutting action of the flame produced by a strong draught, and 

 the ball was surrounded on all sides by an equally hot flame. As 

 regarded cost, Mr. Siemens said that the alteration of present fur- 

 naces would be attended with a considerable expense, as there was 

 all the extra bottom brickwork of the regenerators, besides the 

 separate gas producers and the valves and mains ; but the separate 

 chimneys for each furnace were saved, and the cost of maintenance 

 was greatly reduced, judging from the condition of the glass 

 furnaces that had been twelve months at work. In new works 

 however the cost of construction of the regenerative puddling 

 furnaces would not much exceed the total cost of the present 

 furnaces complete ; and the new furnaces had the advantage of 

 occupying only their own space, without requiring room for a 

 coal pen to each furnace ; they could thus be built closer together 

 and consequently more could be brought within reach of one 

 hammer. 



Mr. Siemens thought a pair of the new puddling furnaces would 

 cost about 300 complete. The regenerative glass furnaces 

 hitherto erected had been very expensive in construction, having 

 heavy iron plates in the sieges and a great deal of ironwork in the 

 fittings of the furnace and in the gas producers, much of which 

 had been greatly reduced or dispensed with in the furnaces sub- 

 sequently put up. In starting the new plan of furnace he had 

 thought it best to keep all the work very substantial, to be on the 

 safe side for strength and durability ; and the gas producers had 

 also been provided each with a separate gas tube and valve, so that 

 each could be shut off from the furnace if desired, to avoid risk of 

 the furnace being interfered with in its working by a defect at 

 any particular point. 



