Today, we find the first modern warship -- on the ocean floor. 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.

I used to wonder why the story of the Monitor and the Merrimack didn't go beyond their famous duel at Hampton Roads in 1862. Why didn't these first steam-powered, iron-clad ships go on to carve out Civil War history? To understand what happened afterward, we should know something about the ships themselves.

Their battle may have been a draw, but they weren't at all alike. The South made their ironclad by hurriedly rebuilding the steam frigate Merrimack. But the Union's Monitor was designed from the bottom up by the immigrant Swedish-American engineer, John Ericsson. Its flat top, riding a foot or so above sea level, with a low rotating turret, was a radical new concept.

They were both river gunboats. They couldn't ride the ocean outside of Chesapeake Bay. When the South evacuated Norfolk, they had to scuttle the Merrimack. The Union Monitor went down while it was being towed along the North Carolina coast in a terrible storm ten months later. At first, water sloshed in faster than the pumps could get rid of it. When the boiler went out, the men bailed while the ship's black cat sat wailing on the main gun.

The Monitor went down in 220 feet of water South of Cape Hatteras lighthouse -- too deep for scuba divers to search. It's a vicious stretch of ocean -- littered with wrecks. All the attempts to locate the Monitor had failed before 1973. Finally a team led by John Newton of Duke University armed itself with side-scan sonar and high-tech photographic equipment. They located 21 other wrecks in the search area before they found the Monitor. It was further north than it should have been -- wind-blown that dark night until it finally carried 16 men and a black cat to their deaths.

Now the Monitor reveals itself to the cameras -- a metal hulk 170 feet long and 40 feet wide. The famous pillbox turret has been knocked off, and it peeks out from under the stern. Suddenly we're gazing straightaway at the beginning of modern naval warfare.

When the Merrimack sank, that was the end of it -- it was just a successful and inventive stopgap -- only that and nothing more. But the Monitor was copied with little basic improvement until WW-I. The Union built a whole string of Monitor gunboats and made very good use of them during the rest of the Civil War.

Now the high technology of 1861 looms up from the dark ocean bed. We make out the main drive-engine, the turret-engine, the screw-propeller drive, the rudder design, the well-conceived armor plate. We see what Ericsson really did. We come away understanding in far clearer terms why that strange, inconclusive duel 130 years ago changed naval history forever.

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

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For more detailed accounts of Ericsson and of the Monitor, with references, see Episodes 695, 795, and 1344.

This episode has been greatly revised as Episode 1632.