WILLIAM SIEMENS, F.R.S. 67 



get up the heat at first, but the furnace retained the heat longer 

 and a higher temperature was obtained ; one night's stoppage 

 required about the same time as the ordinary furnace to get up 

 tin heat again in the morning, but a longer stoppage would cause 

 a somewhat longer time to be required. The principal difficulty 

 experienced in working was from the men putting on too much 

 coal at once, being accustomed to the necessities of the old furnace, 

 and thus choking the fire and retarding instead of accelerating the 

 working of the furnace. 



The experience with the new puddling furnace was too limited at 

 present to determine fully the difference in the time of the pro- 

 cess ; in the furnace now working at Bolton it was found that the 

 iron was about 10 minutes longer in melting down, but was rather 

 quicker in coming to nature than in the ordinary puddling 

 furnaces ; and there was no decided difference in the whole time 

 of working. Some difference in management from the ordinary 

 furnace was of course required, which caused a difficulty at first 

 in carrying out the new plan ; but the principle of the furnace 

 was quite simple, and no more skill and care was needed than was 

 to be looked for in the men concerned. The quantity of fuel 

 consumed and amount of firing required were much less ; and by 

 keeping the fire low a large proportion of oxygenated air was 

 allowed to enter during the puddling process, which was supplied 

 at a very high temperature, preventing fluctuations in the tempe- 

 rature of the furnace ; and the very low draught of the chimney 

 was an important point in greatly reducing the quantity of cold 

 air unavoidably drawn in at the puddling door whilst open during 

 the process. 



Mr. Siemens said he had not attempted the application of the 

 principle at present to steam-engine furnaces, the trials having 

 been first made in those kinds of furnaces where the highest 

 temperature was employed, and where consequently the greatest 

 economy could be effected by the regenerative plan ; but even in 

 the case of steam boilers, a considerable portion of the fuel was 

 generally wasted, by the air being allowed to escape into the 

 chimney at a higher temperature than was required for the 

 purpose of maintaining the draught. 



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