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Why Are Electrical Plugs Different in Europe?

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Jason asks: “I just got back from my first trip to London. I knew going in that the electric plugs were different, but it still threw me off. Is there a reason the plugs evolved differently? What does the rest of the world do?”

In a nutshell, plugs and sockets differ from region to region and even country to country because, at the time they were being developed, no one really saw any reason to make them all the same.

First, a little history. When electricity was first introduced into homes and businesses, it was primarily for powering lights. Early devices and appliances that ran on electricity had to be wired directly into a building’s electric system. It was a little inconvenient—you couldn’t easily move, say, a lamp, from one room to another without wiring it in again—and a potentially hazardous task for most people to attempt.

Starting in the 1880s, several inventors patented variations on a connector that allowed the cord from an appliance to be screwed into a lightbulb socket for power. (Thomas Edison was not one of those inventors, and that was a “curious oversight” on his part, says historian Fred E. H. Schroeder, since he “anticipated almost everything that might relate to the incandescent light bulb and its applications.") These connectors made it much simpler and safer to connect an appliance to power. Since they screwed into the socket, dropping the appliance or pulling too hard on the cord meant you might damage the device, the cord, or the socket.

In the early 1900s, inventor Harvey Hubbell improved on the idea with his Separable Attachment Plug. The plug had an inner connector screwed into the light socket and an outer connector (attached to an appliance by a cord) that plugged into that via two prongs and could easily be popped in and out. It was the ancestor of the modern two-prong plug and socket.

Other inventors soon started coming up with improvements and safety features for this ancestral plug (like a third prong for grounding, insulation for the prongs, and plug shapes that ensured the plug was connected to the socket properly). Just like there’s more than one way to skin a cat, there’s more than one way to design a safe, convenient plug. All over the world, inventors, tinkerers, and engineers approached the task with their own spin, and we wound up with a bunch of different plugs and sockets that all started with the same basic idea, but were designed in very different ways.

At the time, there was no real reason they shouldn’t have been different. The world wasn’t as connected as it is today and electrical appliances weren’t as ubiquitous. International travel wasn’t convenient or attainable by most people, and even those that could hop across the pond probably weren’t going to be lugging a lamp or a fan with them. It didn’t really matter if someone half a world away could use the plug you were developing, so different countries and regions did things their own way and developed plugs and sockets according to local and national standards that often differed very much from each other.

By the time travel and appliance portability were at the point where standardization made sense, electrically wired homes and electric appliances were widespread, and switching to new plugs and sockets was an expensive proposition—which is not to say that a global standard doesn’t exist and a switch over can’t be done. In 1986, the International Electrotechnical Commission unveiled a “universal plug,” known as a Type N plug, that they hoped would become a widespread standard. So far, though, only Brazil and South Africa have adopted the design for their plugs and wall outlets.

For the foreseeable future we’re stuck with the hodgepodge of plugs and sockets that we have.* If you want to see what different countries use, see here and here. And if you’re wondering if one plug is actually better than the others, Tom Scott makes a pretty good case for the British design.

*If you’re abroad, it’s not just the plug and socket that will be different, but possibly the voltage and frequency of household electricity, which differs from region to region. Even if you have a plug adapter for when you travel, the voltage disparity means that your gadgets might not work as well, or could become damaged. The voltage split has its roots in the “War of the Currents,” which is an interesting story.

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Big Questions
Why Is the American Flag Displayed Backwards on Military Uniforms?
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In 1968, famed activist Abbie Hoffman decided to crash a meeting of the House Un-American Activities Committee in Washington by showing up in a shirt depicting the American flag. Hoffman was quickly surrounded by police, who ripped his shirt off and arrested him for desecration of the Red, White, and Blue.

Hoffman’s arrest is notable today because, while it might be unpatriotic to some, wearing the American flag, burning it, or otherwise disrespecting it is not a violation of any federal law. In 1989, the Supreme Court ruled that it would be unconstitutional to prosecute any such action. Still, Americans have very fervent and strict attitudes toward displaying the flag, a longstanding symbol of our country’s freedom. According to the U.S. Flag Code, which was first published in 1923, you shouldn’t let the flag touch the ground or hang it upside-down. While there’s no express prohibition about reversing the image, it’s probably a safe bet you shouldn’t do that, either.

Yet branches of the U.S. military are often spotted with a seeming mirror reflection of the flag on their right shoulder. If you look at a member in profile, the canton—the rectangle with the stars—is on the right. Isn’t that backwards? Shouldn’t it look like the flag on the left shoulder?

The American flag appears on a military uniform
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Not really. The flag is actually facing forward, and it’s not an optical illusion.

When a service member marches or walks forward, they assume the position of a flagpole, with the flag sewn on their uniform meant to resemble a flag flapping in the breeze. With the canton on the right, the flag would be fluttering behind them. If it were depicted with the canton on the left, the flag would be flying backward—as though it had been hung by the stripes instead of the stars nearest to the pole. The position of the flag is noted in Army Regulation 670-1, mandating the star field should face forward. The official term for this depiction is “reverse side flag.”

As for Hoffman: His conviction was overturned on appeal. In 1970, while at a flag-themed art show in New York, he was invited to get up and speak. He wore a flag shirt for the occasion.

Have you got a Big Question you'd like us to answer? If so, let us know by emailing us at bigquestions@mentalfloss.com.

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Big Questions
What Causes Sinkholes?
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Mark Ralston/AFP/Getty Images

This week, a sinkhole opened up on the White House lawn—likely the result of excess rainfall on the "legitimate swamp" surrounding the storied building, a geologist told The New York Times. While the event had some suggesting we call for Buffy's help, sinkholes are pretty common. In the past few days alone, cavernous maws in the earth have appeared in Maryland, North Carolina, Tennessee, and of course Florida, home to more sinkholes than any other state.

Sinkholes have gulped down suburban homes, cars, and entire fields in the past. How does the ground just open up like that?

Sinkholes are a simple matter of cause and effect. Urban sinkholes may be directly traced to underground water main breaks or collapsed sewer pipelines, into which city sidewalks crumple in the absence of any structural support. In more rural areas, such catastrophes might be attributed to abandoned mine shafts or salt caverns that can't take the weight anymore. These types of sinkholes are heavily influenced by human action, but most sinkholes are unpredictable, inevitable natural occurrences.

Florida is so prone to sinkholes because it has the misfortune of being built upon a foundation of limestone—solid rock, but the kind that is easily dissolved by acidic rain or groundwater. The karst process, in which the mildly acidic water wears away at fractures in the limestone, leaves empty space where there used to be stone, and even the residue is washed away. Any loose soil, grass, or—for example—luxury condominiums perched atop the hole in the ground aren't left with much support. Just as a house built on a weak foundation is more likely to collapse, the same is true of the ground itself. Gravity eventually takes its toll, aided by natural erosion, and so the hole begins to sink.

About 10 percent of the world's landscape is composed of karst regions. Despite being common, sinkholes' unforeseeable nature serves as proof that the ground beneath our feet may not be as solid as we think.

A version of this story originally ran in 2014.

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