Today, a little exercise in blowing smoke. 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 get one comment over and over. It is that war stimulates inventions, which then serve us in peacetime. Don't we need war so we'll keep inventing? Didn't the atom bomb give us nuclear power? Didn't war give us the jet plane which now takes us from Houston to Paris? The truth is: war produces very little new technology. It is even an enemy of invention.

Soon after WW-I, Lisa Meitner began bombarding heavy elements with fast neutrons. In 1939, she wrote a paper describing the enormous release of energy when uranium fissions into barium. She expressed hope for a "promised land of atomic energy." The result was a furious attempt, on both sides, to build an a-bomb.

But the Jewish/German Meitner refused to have anything to do with anyone's bombs. And we didn't return to atomic power -- to her original intention -- until after the war.

Same story with the jet plane: the first jet flew in 1939, before WW-II. The first jets in combat were German designs that'd also been on the drawing boards before the war.

But writer Alexander Roca gives us one invention, conceived in war, which really did serve in peace. It began when chemical warfare people went to inventor Thomas Shelton and asked him to invent a way to throw poison gas from a distance. You obviously can't squirt poison gas from a nozzle. It'll diffuse within a few feet and harm the person holding the nozzle.

Shelton was famous for his knowledge of vortex shedding in airplane design. So he sat down and invented a large bell-shaped chamber. When he exploded a shotgun shell in one end, it burped a gigantic smoke-ring out of the other. A smoke-ring is a vortex of spinning gas that holds together while it propels itself forward. This vortex was 18 inches across, and it traveled 150 feet. We're told that the gadget made "an eerie howling sound."

From there, he went on to interest the Air Corps in a huge version that would fire vortices large enough to knock enemy airplanes out of the sky. But, in the end, the war effort went -- as it usually does -- in safer and more conventional directions.

Shelton's vortex machine came to nothing. So, after the war, he turned it into a toy gun that knocked targets over with an air vortex. He called it the "Flash Gordon Air Ray Gun." Popular Mechanics named it Toy of the Year in 1949. The Lion Match Company invented a pellet that generated smoke for the vortices.

So, I cannot categorically claim that no civilian technology comes out of war. Now and then it does. But remember: when people try to claim that war is the mother of invention, they are, by and large, just -- blowing smoke.

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

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Roca, A., Killer Air Ray. American Heritage of Invention and Technology, Summer 1995, Vol. 11, No. 1, p. 64.