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No. 1082:
Cuneiform and Turbines

Today, we finally get back to where we started. 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.

Technology has an odd way of starting out where it will one day end up -- of wandering all over the map before it gets there. Take the earliest writing, done with a stylus on clay tablets. Now, 5000 years later, we've gone from clay through papyrus, sheepskin, and paper, to increasingly dense magnetic storage. Finally, CD ROM brings us back to engraving -- first on metal. But now, in the quest for permanence, we're learning to micro-engrave words on ceramic surfaces. So, it seems, we've come full circle.

That's how it was with steam power. In the 250 years before Cleopatra, the Egyptians created all kinds of steam-driven toys. They all worked on the same principle: they had small water tanks heated by a fire. Steam escaped through jets to drive the toy.

But no one could quite figure out how to make steam jets produce useful power. Finally, in the early 1700s, English engineers came up with a completely different scheme for getting power out of steam. They used steam to drive pistons. Soon, the whole world was powered by piston steam-engines, and those Egyptian jets were forgotten.

But then, in the 1880s, we had to drive our new electric generators. Generators turned faster than a big piston could move. The answer was to blow steam jets onto fast-turning propeller blades. We created the steam turbine. And that's what we use to take power from steam today, even in nuclear plants. Like cuneiform on clay, those ancient Egyptian jets had finally come back.

Historian Joseph Needham underscores that point. Before England gave us piston engines, the Jesuits were a strong presence in China -- teaching, learning, and ordaining priests. In 1671 one of those priests, Min Mingwo, built a set of steam-driven model boats and cars to entertain his emperor. His boilers supplied steam jets. They fell on fast-turning paddle-wheels which drove gear trains to slow their motion and power the vehicles.

Mingwo had created a complete functioning steam turbine. And he did it well. His model car ran, nonstop, for two hours. There's a working reconstruction of Mingwo's car in the Milan science museum. It's the prototype of a machine poised to transform the world.

But it didn't. In 1671 we still weren't ready for this 2000-year-old idea. Eighteenth-century England turned instead to piston engines for her mills and mine pumps. Steam jets could no more have gone straight from the court of Cleopatra, or the Chinese emperor, into modern service than cuneiform writing could.

So I think about those first unfinished ideas: the airplane with flapping wings, a cannon launching a satellite. That first idea has the oddest way of coming back at the end -- just when we least expect it.

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

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Ronan, C.A., The Shorter Science and Civilisation in China: An abridgement of Joseph Needham's Original Text. Cambridge: Cambridge University Press, 1994.