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No. 463:

Have you ever thought about chimneys? Well, let's do that today. The University of Houston's College of Engineering presents this series about the machines that make our civilization run, and the people whose ingenuity created them.

Good King Wenceslas went out,
On the Feast of Stephen,
When the snow lay round about,
Deep and crisp and even.

Wenceslas was a real King of Bohemia. He got into political trouble in 1400 and went downhill from then on. He ended as an alcoholic. As for his mythical trip into the cold, that was on December 26th -- the feast of Saint Stephen. It's a poor night to be out in Bohemia. And medieval records show that winters were far worse then than they are now. The medieval poet François Villon shivered and called that time of year,

... the dead season when wolves live off the wind, and people stay home near the fire ...

By 1400 the indoors had become bearable in winter. Six hundred years before, in Charlemagne's time, even the indoors was quite ghastly in winter. We needed far better tools of survival before we'd ever build civilization in Northern Europe.

The technologies that brought us out of the forests began appearing just after Charlemagne -- after AD 800. We learned to harness the horse and waterpower. No less important, we learned to keep the chill of winter out of our bones.

The chimney was the key. Before its invention, whole families crammed into one large room with an indoor fire. They were utterly without privacy. They vented the smoke, but the arrangement was less efficient than a fire in an Indian wigwam.

Chimneys and fireplaces changed all that. Hot smoke in a chimney buoys up and draws fresh air into a small fire. Now we could divide buildings into rooms and equip each one with a fireplace and chimney.

The first stage of that arrangement turned up in a Swiss monastery in AD 820. A system of flue pipes took smoke from several fires. They fed it into three smokestacks. Individual chimneys and fireplaces followed, but we're not sure just when. Evidence is very skimpy before AD 1100.

That's because only the clergy and the clerks of kings wrote in the Middle Ages. They told about politics and wars. They hardly mentioned the real agents of social change. The craftsmen who really shaped the world stayed anonymous and invisible.

Kenneth Clark's great television series Civilisation described the world just after the chimney was invented. He didn't talk about chimneys, either. But his title was The Great Thaw. That was imagery for the 11th-century artistic and technological revolution. The first step on the road to building that civilization was easing human misery -- driving back cold and hunger. We couldn't build cathedrals, or lunar landers, until we'd first learned the technologies of our own survival.

I'm John Lienhard, at the University of Houston, where we're interested in the way inventive minds work.

(Theme music)

Dresbeck, L.R. Winter Climate and Society in the Northern Middle Ages: The Technological Impact. Humana Civilitas: Sources and Studies Relating to the Middle Ages and the Renaissance, Vol. I. On Pre-Modern Technology and Science (B.S. Hall, D.C. West, eds.) Malibu: Undena Publications, 1976.

I am grateful to Pat Bozeman, Head of Special Collections, UH Library, for drawing my attention to this source and making her uncatalogued copy available to me.