88 FRANK HEARNE CROCKARD 



to 1,912 pounds per ton of iron; the rate of driving, which 

 averaged from 22,000 to 25,000 cubic feet of air per minute 

 the previous year, had now fallen to 16,000 cubic feet. This 

 achievement marked the next important step, character- 

 izing the period as one of great production, low fuel, and slow 

 driving. While these results were very gratifying, they 

 proved merely precursory of the greater achievements of 

 the new epoch which has since been seemingly resolved into 

 an interminable era. 



In September, 1889, the Edgar Thomson group again 

 forged to the front with the blowing in of an 80 foot stack, 

 containing 18,200 cubic feet. This furnace had seven six 

 inch tuyeres delivering 25,000 cubic feet of air per minute — 

 a return to the figures of 1880, but productive of entirely 

 different results. The temperature of the entering blast 

 remained about the same, 1,100 degrees Fahrenheit, but the 

 pressure had reached 9|- pounds, while the output (for the 

 month of April, 1890) reached 10,075 tons on a coke con- 

 sumption of 1,884 pounds. In 1880, 135 cubic feet of fur- 

 nace volume were required per ton of product; in 1890, this 

 figure had fallen to less than 60 cubic feet. Intensity of 

 production was the order of the day, and, thanks to the daring 

 initiative of American metallurgists, has not yet found its 

 prescribed hmits. 



An interesting example of recent furnace construction 

 is found in the Youngstown plant of the National Steel Co. 

 These furnaces are 106^- feet high, 23 feet in the bosh, and 

 have a hearth diameter of 15 feet, giving a capacity of 26,500 

 cubic feet. Blast at the rate of 50,000 to 60,000 cubic feet 

 per minute is introduced through sixteen 6-inch tuj^eres. 

 The normal pressure is about 15 pounds, but the blowing 

 equipment is designed to furnish 25 pounds when necessary. 

 These furnaces were blown in during 1900; in the month of 

 October of that year one furnace produced 17,600 tons with 

 a fuel consumption of 1,777 pounds per ton; a second stack 

 during the same period produced 17,412 tons with, a fuel 

 consumption of 1,790 pounds. Both furnaces lost a day 

 during the month. 



