On the Blajl of Iron Furnaces. 1 15 



only in proportion to the quantity of air decompofed in the procefs of combuftion, 

 without regard to its greater velocity ; that is to fay, whether or not the fame quantity of 

 air was forced, in the fame time, into th? furnace through a fmall pipe, or through one 

 of larger dimenfions ; for, in attending to the procefs of a common air furnace for re- 

 melting of iron, where there is a very large quantity of air admitted through the large areas 

 between the bars, it is well known, that a much greater intenfity of heat is produced than 

 takes place in a blaft furnace, and yet the air does not enter into the fire through the 

 bars with increafed denfity or great velocity. I therefore thought it probable, that in- 

 creafing the quantity of air, thrown into the blaft furnace in a confiderable degree, although 

 the velocity or denfity might be much lefs, would have the efFe£l; of increafing its heat, and 

 operations, and produce. And as, from the principles above ftated, with regard to the 

 machinery, I faw I could greatly increafe the quantity of air thrown into the furnace, by 

 enlarging the diameter of the blow-pipe, and regulating the engine accordingly, without 

 being obliged to employ more power, I was anxious to make this experiment. 



A fyftem of management, of which I did by no means approve, was adopted by the 

 other partners of the Devon company, foon after the works were begun to be eredled ; and, 

 in the profecution of it, they ordered their fecond furnace to be put in blaft, without per- 

 mitting thofe meafures to be taken that were neceflary to provide and maintain a fufficient 

 ftock of materials ; and alfo without allowing their blowing machine to be completed, 

 according to the orignal defign, by the addition of its fecond boiler. As might have been 

 expefted, a trial of feveral months to carry on two furnaces, with only half the power of 

 fteam that was neceflary, and an inadequate ftock of materials, proving unfuccefsful, the 

 company, as a remedy, inftead of making up the above deficiencies, ordered one of the 

 furnaces to be blown Out, and ftopped altogether. This improper meafure, however, 

 afforded me the opportunity of immediately putting in practice the plan I have men- 

 tioned. 



When one of the furnaces was ftopped, the other continued to be blown by a blow- 

 pipe of 2| inches diameter, and the produce of the furnace, for feveral weeks thereafter, 

 was not 20 tons of iron per week at an average. The engine at this time was making 

 about 16 ftrokes a minute, with a ftroke of the air pump, about 4 feet 8 inches long; but 

 when I altered the diameter of the blow-pipe, firft to 3, and immediately after to 2t; inches 

 diameter, and regulated the working gears of the engine, fo as to make a ftroke of 5 feet 

 2 inches long, and about 19 ftrokes in a minute, on an average, the produce was im- 

 mediately increafed. It continued to be, on an average of nine months immediately after 

 this improvement, at the rate of 33 tons of iron per week, of as good quality as formerly ; 

 for during this period, from the 21ft November 1795 to July 30, 1796, this one furnace 

 yielded 1188 tons of iron. No more coals were confumed in working the blaft engine, 

 or other expences about the blowing machine incurred, and therefore no more power was 

 employed to produce this great effed. It is alfo of much importance to remark, that the 



0^2 confumptioH 



