Unbound: How Eight Technologies Made Us Human and Brought Our World to the Brink

by Richard L. Currier

And in 1709, the Englishman Abraham Darby successfully smelted iron in a blast furnace that burned coke instead of charcoal. Darby’s simple innovation had far-reaching consequences. First, it took the pressure off the dwindling reserves of forest, making it possible for the first time to produce high-quality iron in many areas of Europe that had become dangerously deforested but were nevertheless rich in coal. Second, the charcoal fires traditionally used for smelting were subject to being crushed and smothered if too much iron ore was dumped in on top of them, but the greater physical strength of coke could support much heavier loads of ore. This made it possible for much larger quantities of iron ore to be loaded into the furnace at one time. As a result, blast furnaces were soon being built far larger than was previously possible, and these new furnaces produced greater yields from the same investment of time and labor. Finally, it was far cheaper to mine coal and convert it into coke than it had been to cut down entire forests and saw up the trees in order to produce charcoal from firewood.