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What Makes #2 Pencils So Special?

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Most of us pick up pencils—and lose them—without giving them a second thought. Pencils are a bit more interesting than you might, think, though. Here are a few not-so-frequently asked questions about everyone's second-favorite writing implements, including the story of a time when pencil sharpeners were illegal.

WHAT MAKES #2 PENCILS SO SPECIAL?

When it comes to pencils, #2s are actually the absolute middle of the road. While we number our various grades of pencils in the U.S., the rest of the world uses a system of numbers and letters to describe how hard and how black a pencil's lead is. An American #2 pencil (roughly) corresponds to an HB pencil on the rest of the world's scale. The lead is not too dark and not too light, and it's not too hard or too soft.

Pencils numbered higher than 2 have harder leads and are often used by engineers, architects, and draftsmen because of their harder points. The underlying logic here is that the harder point gives the user greater control of the lead. You'll find softer leads in pencils numbered below 2, which are popular with artists because they can help create a wider spectrum of tones than one would achieve by sticking solely to a #2 pencil.

ACK! I USED A #3 PENCIL ON THE SAT! IS MY LIFE OVER?

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No ... but you're probably destined for a life of hard labor rather than college. No, not really. It's hard to get a straight answer on this question, but there are quite a few reports from people online who messed up by using the wrong grade of pencil and still did just fine on their SATs. The general consensus seems to be that the SAT's scanners will read a #3 pencil's mark just the same as it would read one from a #2 pencil. Some people do feel, however, that the harder lead in a #3 pencil makes erasing tougher and ups the chances that a stray smudge or incompletely erased mark will be read by the scanner and end up hurting your score. So it's probably best to err on the safe side and double-check your pencil type before heading into the exam.

IF THE REST OF THE WORLD USES A SYSTEM OF NUMBERS AND LETTERS TO GRADE PENCILS, WHY DO WE USE JUST NUMBERS?

Thank Henry David Thoreau and his old man. When graphite was discovered in New Hampshire during the 1820s, John Thoreau and his brother-in-law Charles Dunbar built their own pencil factory. The only problem was that New Hampshire graphite was pretty crummy; it smeared and made for pretty poor pencils.

Enter a young Henry David Thoreau. Before he wrote about civil disobedience and spent his time at Walden Pond, he worked at the family pencil company. Thoreau perfected a process of using clay as a binder to make the soft, loose graphite hard and suitable for pencils. Suddenly the New England graphite could be used to make a pencil that didn't leave giant smears, and the Thoreaus' business took off. By the middle of the 19th century, the Thoreaus were selling pencils with varying graphite hardness, which they numbered one through four.

IF THE CENTER OF THE PENCIL HAS BEEN MADE OF GRAPHITE FOR SO LONG, WHY DO WE CALL IT "LEAD"?

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Blame shoddy 16th century chemistry for this one. When a giant graphite deposit was found in England during the 16th century, it eventually found a use as a writing implement. However, early chemists weren't exactly sure what the useful gray substance actually was. They assumed it was some sort of lead, and the term "pencil lead" came into use—even though there wasn't any lead involved.

WHY ARE PENCILS PAINTED YELLOW?

According to most stories, our pencils are yellow as a result of a clever marketing gimmick. In 1889, the Hardtmuth company of Austria introduced a new line of fancy pencils at the World's Fair in Paris. The pencils were named Koh-i-Noor after a famed Indian diamond, and they contained the world's finest graphite from the Far East. They were also painted yellow, which was unusual at the time.

Some historians claim that the Austrian company painted their pencils yellow as a subtle nod to the yellow on the flag of Austria-Hungary. Others claim the yellow was an even subtler nod to the Far Eastern graphite in the pencils; the color yellow is associated with royalty in China. In either case, the new yellow pencils were a hit, and soon other companies began painting their own wares yellow in an attempt to swipe some of Hardtmuth's business.

DOES THE LITTLE METAL BAND THAT HOLDS THE ERASER ON THE PENCIL HAVE A NAME?

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It sure does. It's called a ferrule, a combination of the Latin words viriola ("small bracelet") and ferrum ("iron").

HAVE PENCIL ERASERS GIVEN US ANY COMMON WORDS?

You bet. According to records from the 18th century, the elastic substance from tropical plants got its name thanks to its common use of being rubbed over pencil marks to erase them. Since using this substance as an eraser required a lot of rubbing, people began calling it rubber. Another name for rubber from the same era that didn't catch on quite as well was lead-eater

WHEN WAS IT ILLEGAL TO OWN A PENCIL SHARPENER?

If you owned a pencil sharpener in early 20th century England, you had a hot little piece of contraband. At the time, the supply of the red cedar that had historically been used in pencils was getting perilously low, so the government briefly outlawed pencil sharpeners in order to limit waste from overzealous sharpening. Eventually the mechanical pencil and the discovery of incense-cedar's usefulness in making pencils solved this problem, and pencil sharpeners became street legal once again. Phew!

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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?

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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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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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