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No. 264:
Oliver Evans - A Revision

Today, we talk about muskets, steam engines, and motorcars. 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.

A new idea rose up in the 1600s -- the idea that gases could exert power. The steam engine was finally built after a century of experimenting with air, steam, and gunpowder. Gunpowder didn't work out. But the force that drove a musket ball faster than an eye could follow it tempted our imaginations. By 1700 we finally had workable steam engines.

Thomas Newcomen's first practical engine didn't really reveal its kinship with muskets. It produced power when steam condensed in its huge cylinder and sucked the piston in. From then on, for many years, steam engines operated at low pressures. James Watt finally made engines that ran above atmospheric pressure, but not much. He didn't think we should fool around with high-pressure steam.

The first important American steam-engine maker was Oliver Evans -- born in 1750. As a young man he'd amused himself with a neat little experiment. He put some water in a gun barrel, corked it tightly, and then heated it until the cork blew out. "Why not make steam engines like that!" Evans said, and he did. The kinship of his steam engines with muskets was quite clear. They had small high-pressure cylinders -- like gun barrels.

They weren't awfully efficient, but they were light, and they performed well. They were naturally suited to America's need for transportation. Yet Evans spent years trying to find backing for some sort of steam-powered vehicle. It was 1805 before he finally contracted with the city of Philadelphia to build a dredge for their harbor. He closed himself in his workshop while neighbors wondered aloud if he, like Noah, was arming against the flood.

And so, one day that summer, the doors of Evans's workshop finally swung open, and out rolled the most remarkable transportation machine since Noah's ark. It was a gigantic steam-powered behemoth that he called the Oructor Amphibolos -- Latin for "Amphibious Dredge." This strange, awesome machine could have lumbered straight off the set of a Mad Max movie. It rolled down the streets, around Center Square, and off into the Schuylkill river, where it sailed about, dredging mud.

Evans sensed our need for powered transportation. In one stroke, he'd made our first horseless carriage, and he'd invented a steamboat as well. During the next decade it all began in earnest. Quite suddenly Robert Fulton's steamboat, and railroad trains with high-pressure engines, were there to carry us across this sprawling, inaccessible land.

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

(Theme music)

Pursell, C.W., Jr., Early Stationary Steam Engines in America. Washington: The Smithsonian Institution Press, 1969, Chapter 4.

Flexner, J.T., Steamboats Come True. 2nd ed. Boston: Little, Brown and Company, 1978, pp. 267-8.

The very first program I did, Episode 1, was an ongoing benchmark for me. And so I redid it twice, once as a simple revison (this Episode 264) and once as an elaboration of Oliver Evans's story (Episode 285).



(From the 1832 Edinburgh Encyclopaedia)
Oliver Evans's High-Pressure Columbian Engine