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No. 238:
Momsen's Lung

Today, we look for the safest way out of a submarine. 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.

Writer Ann Jensen tells about the German engineer Wilhelm Bauer. Bauer was an early submarine-builder -- during the 1850s. When one of his first boats started to collapse in sixty feet of water, Bauer was cool and quick-thinking. He let water leak in until the pressure had equalized and a small breathing space remained. Then he opened the hatch, and, in his words, he and his two crewmen simply shot to the surface "like bubbles in a glass of champagne."

When WW-I began, 63 years later, the opposing forces had 214 military submarines. These new machines would clearly be primary actors in the horrors that were to follow. Many men were destined to die in those claustrophobic chambers.

So the best minds went to work on inventing a kind of underwater parachute -- a breathing apparatus to get men to the surface. Bauer's experience was forgotten as inventors made elaborate devices and even more elaborate strategies for using them. I read about them in magazines when I was a boy during WW-II. The Momsen lung was the method of choice. It cleaned carbon dioxide out of the air you exhaled, it enriched it with oxygen, and it recycled it.

With the Momsen lung, you first adapted to high pressure, then you slowly rose to the surface to avoid getting the bends. No "shooting upward like champagne bubbles" here.

WW-II magazine articles weren't meant to frighten young men away from submarine service. But the grizzly truth was that 94 percent of the men known to be alive when submarines were disabled died -- either inside them or on the way to the surface. Worse yet, only five of the men that lived were saved by the Momsen lung.

After the war, naval people took stock of what'd happened. Only then did they begin to teach the method of free ascent. You fill your lungs with air; you let yourself out of the submarine at any depth up to 300 feet; and then you exhale on the way up. The air in your lungs expands as the pressure decreases. You never run out of air. You never adjust your body to high pressure. And you're never threatened by the bends.

In retrospect, those breathing devices killed far more people than they saved. They made sailors think it was impossible to get to safety on their own. It's a hard-learned lesson that engineers have to learn over and over again: that no technology can sometimes be better than a highly-developed one -- that the really inventive designer alters the problem itself before he solves it. The real problem here wasn't providing air on the way to the surface. It was getting a person safely to the surface. Wilhelm Bauer figured that one out, on the spot, way back in 1851.

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

(Theme music)

Jensen, A., Why the Best Technology for Escaping from a Submarine is No Technology. American Heritage of Invention and Technology, Summer 1986, pp. 44-49.