Today, we visit the remains of two World Wars. 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.

Scapa Flow is a sheltered bay nestled in the Orkney Islands just beyond the northernmost tip of Scotland. The Orkneys are flat, green, and quite beautiful. A buoy with a memorial plaque bobs in Scapa Flow. Eight hundred sailors from the English battleship Royal Oak are entombed below it. I was in fourth grade when a German U-boat made its daring raid into the very middle of this sheltered anchorage and found the Royal Oak there on Friday the 13th -- in October, 1939.

One torpedo from the first salvo hit the ship, and it did minimal damage. It wasn't clear to the crew what the muffled WHUMP! really meant. The Germans were given the twenty minutes they needed to reload a second salvo. This time they scored three solid hits. In minutes the ship had capsized and sunk. It landed with its superstructure crushed on the bottom and the keel just thirty feet from the surface. Only a third of its crew -- chilled and oil-soaked -- got out alive.

It was frightening news for me. The gathering clouds of WW-II had darkened my childhood ever since the Japanese and Italians invaded China and Africa. Now the pride of the British Fleet had been sunk in home waters. In my childish fear, I asked how long it would be before I saw enemy submarines in the Mississippi.

The Royal Oak was state-of-the-art naval weaponry when it was built in 1914. Its great 15-inch guns were then the largest ever put on a ship. By 1939 it bulged with protective siding to absorb torpedo impacts. But technology had moved too quickly, and that siding wasn't enough to absorb the new German torpedoes.

The Royal Oak was, ironically, not the first battleship that went to the bottom in that cold, quiet anchorage. Twenty-nine years earlier, after WW-I, the Allies had herded the defeated German Navy into Scapa Flow. Then, without warning, German skeleton crews made a kamikaze decision. They scuttled their whole fleet before the Allies could react.

So there's far more than just the Royal Oak at the bottom of Scapa Flow. The surface of those waters is still smoothed today by slow, unremitting oil leaks that've gone on for 70 years. The well-built hull of the Royal Oak still holds air pockets that its drowning sailors never reached.

Of course, we saw no German submarines in the Mississippi River. Eight hundred English sailors were a tiny fraction of the millions who died to prevent that. And Scapa Flow is a mute monument to the head-over-heels arms races that fueled those two failed wars of conquest. It is as beautiful a cemetery for yesterday's war machines as it is for the men who died in them.

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

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Morris, K. and Rowlands, P., Exploring Shipwrecks. New York: Gallery Books, 1988, pp. 110-139.

This episode has been greatly revised as Episode 2536.