The Metal Manometer


At first, Eugene Bourdon was annoyed when he saw what his worker had done to the metal tube, but then it gave him an idea that would save countless lives. In this episode, Dan Holohan tells us about an invention that’s at the heart of every pressure gauge ever made (even to this day).


Episode Transcript

At first, Eugene Bourdon was annoyed when he saw what his worker had done to the metal tube. The tube was in the shape of a spiral and it was to go into a laundry machine they were building in Bourdon’s shop. But the worker had somehow managed to flatten most of the tube, and that was not good. The worker, of course, was nervous as Bourdon looked at the tube and thought about whether or not this was a total loss.

But then Bourdon had an idea. He closed one end of the spiraled metal coil and connected the other end to a water pump. He figured the water pressure might be able to make the tube round again because the metal was thin enough. And to his delight, it worked!

But here’s the best part. As the tube regained its shape, it also began to unroll from its spiral. Bourdon stood and watched this with great interest. It suddenly dawned on him that what he was witnessing could possibly become a key to a new sort of manometer to measure high pressure.

Working with metal was not unusual for Bourdon. He made watches and he had always loved mechanical devices of all sorts. He was born in Paris on April 8, 1808. His father was a well-to-do silk merchant. He sent Bourdon to good schools and when Eugene was old enough, his father sent him to Nuremberg for two years to learn how to speak German. When he returned, Bourdon helped his father in the silk business until his father died in 1830. Eugene then worked for an optician for two years and continued his love of all things mechanical.

In 1832, he set up his own shop. He built model steam engines at a time when steam locomotives and steam-powered ships were new and regularly exploding. He was trying to find a solution to that problem. Each explosion left tragedy behind because those boilers all ran at high pressure. But at the time, there was no reliable way to gauge high pressure. Mercury manometers were fine for reading low pressure, but building a mercury manometer for a moving train or a steaming ship was not practical. The U-tube of such a device would have to be enormously tall and perfectly balanced.

He thought about this as he worked in his shop, and then that lucky day arrived when his worker accidentally flattened that metal tube for the laundry machine. Bourdon decided if he created a flattened tube of thin metal in the shape of the letter C and added to the closed end of this tube some small gearing and a pointer, he would have the makings of what he came to call the metal manometer. This simple device would be able to read high pressure. If you’ve ever opened a pressure gauge and looked inside, you’ve seen Eugene Bourdon’s invention. The Bourdon tube became the heart of every pressure gauge ever made, even to this day.

He patented his device in Paris on June 18, 1849, and with great excitement, entered it in the competition at the 1849 Paris World’s Fair. The judges immediately understood what Bourdon had created, and what this device meant to the safety of anyone near steam locomotives or steamships. They awarded his invention a gold medal.

In that same competition, a young French student, Timoleon Maurel showed a mechanical calculator he called the Arithmaurel. This small box filled with many gears and dials was able to add, subtract, multiply and divide numbers in just minutes! It was a modern wonder, and it, too, won a gold medal. To think that one of the earliest computers and the common pressure gauge found their first audiences at the same show makes me smile.

Oh, and also shown at that World’s Fair, but scoffed at by the judges, was Belgian inventor Adolphe Sax’s offering. He invented a new sort of musical instrument he named after himself. The judges thought this instrument would never amount to much because it wasn’t a woodwind. No one, they said, will ever play the saxophone.

It’s a good thing John Coltrane never got the word.

In 1850, Bourdon started his own company to make his metal manometer, this new sort of pressure gauge. They immediately found a home in hundreds of steam locomotives and ships all over Europe, saving countless lives. His gauge also allowed engineers a way to develop a whole range of industrial machinery that operated at higher pressure. None of this would have happened had Eugene’s employee not crushed that laundry-machine coil.

In 1851, the French government awarded Bourdon its Chevalier de la Légion d’honneur, the highest civilian honor possible. He continued to make and market his metal manometer until his patent ran out in 1875. Many other companies jumped on the bandwagon after that, and not much has changed in the pressure-gauge’s original design since then.

We Americans were also having many steam-boiler explosions during the time when Bourdon first came up with his metal manometer. Fortunately, he wasted no time in selling the U.S. patent rights for his new gauge to the American merchant, Edgard Ashcroft, and many more lives were saved. Today, we know these as Ashcroft gauges.

Bourdon’s story came to an end on Sept. 29. 1884, when they laid him to rest in Paris’ famous Père Lachaise Cemetery. His grave is among those of many famous writers, artists and musicians. Here you will find the remains of Oscar Wilde, Sarah Bernhardt, Frederic Chopin, Claude Debussy, Edith Piaf, Marcel Proust and many others. Oh, and also Mr. Jim Morrison of The Doors fame.

The cemetery has a website, where they list all the famous people who rest there for all eternity. I looked for Eugene Bourdon’s name, but they do not include him on that list. Apparently, he is no longer famous enough. But that doesn’t surprise me, and it shouldn’t surprise you either. These days, the pressure gauge is a commodity. Yet it won a gold medal at the Paris World’s Fair in 1849. Yes, it stood side-by-side with one of the first computers. And yes, it even beat out the saxophone for the big prize. But these days, it’s just a simple pressure gauge. Ho hum.

Ah, but know this: There was a time in the world when people perished in horrible boiler explosions for lack of that simple gauge. And those explosions would still be running rampant now if not for Eugene Bourdon’s invention.

Give that some thought the next time you screw a gauge into place, or when you glance at one to get a reading. That beautiful device didn’t happen on its own. Consider that.

Today, people will walk the narrow paths of Père Lachaise Cemetery. Some will carry a flower to place on the grave of the late Mr. Morrison, dead at 27 years of age. They may walk by Eugene Bourdon’s grave on their way and never consider what that man did for us. If you should someday find yourself in Paris, please carry a flower for him. In the meantime, please smile and nod at a pressure gauge. It’s watching out for you.

I hope you liked that tale. And if you did, please share it with your friends. And if you haven’t already, please subscribe to this podcast. I have many more Dead Men Tales to share with you, and I appreciate you for taking the time to listen. Thanks!

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