Prior to their construction, blast furnaces in the United States did not exceed about 50 tons of iron yield per day, and the prevailing attitude of operators was to follow "rule of thumb" methods and not to attempt anything beyond the rated capacity.

[4] Lucy and Isabella began an era of scientific refinement of the process, of relentless experimentation with ways of producing more iron output from a given amount of input ore, increasing throughput, and pushing the furnace beyond its design capacity.

Owing to this approach and its large size (the 75-foot stack was larger than any previously constructed), the Lucy quickly became a leader in volume of production.

[2] In 1890, English metallurgist Sir Lowthian Bell denounced operation of the Lucy as "reckless," with the practices wrecking the lining of the furnace such that it had to be replaced every three years.

"[6] Unusually, Carnegie employed a chemist in the administration of the furnace, and credited having "almost the entire monopoly of scientific management" in making Lucy "the most profitable branch of our business.

[8] In addition to their sheer size, a key to Lucy's prodigious output was their massive vertical steam reciprocating blowing engines, which provided 16,000 cfm of hot air at 9 psi.