Why Are Traffic Lights Red and Green?

istock.com/rzelich
istock.com/rzelich

The very first traffic light, installed outside the Houses of Parliament in London in December 1868, had red and green gas lamps for nighttime use. The device was pretty crude, and less than a month after it went operational, it exploded and killed the unfortunate traffic cop who was operating it.

Obviously, we’ve come a long way in traffic light technology, but we’ve stuck with the same color scheme. What is it about red and green that gave them such lasting power?

The guys who made that first traffic light borrowed their palette from the railroads. British railwaymen of the time often used red, green, blue, black and white flags, semaphores and lamps for signaling. In January 1841, faced with Parliamentary investigation over a number of accidents, the major railroad managers met to discuss safety issues. Henry Booth of the Liverpool and Manchester Railway was a driving force at the meeting and recommended standardized hand signals and color schemes. The colors adopted were those used by Booth’s lines: red to indicate danger, white to indicate safety and green to indicate "proceed with caution."

Booth’s use of these colors, in turn, seems to have come from a common practice in heavy industry of the era. Many motors and other industrial equipment had indicator lights that were red when the equipment was stopped and green when it was running. Since people were already familiar with this color scheme and its meaning, it makes sense that it was handed down into the railroad industry and then to traffic lights.

As for why the early industrialists chose red to mean stop and green to mean go, we can only speculate. In color symbolism, red generally evokes danger and makes it a good choice for a warning signal. Green, on the other hand, is calming. While that doesn’t seem to lend itself well to “go,” it may have been chosen for a more practical reason - it contrasts well with red and is highly visible without being harsh or distracting.

11 Masks That Will Keep You Safe and Stylish

Design Safe/Designer Face Covers/Its All Goods
Design Safe/Designer Face Covers/Its All Goods

Face masks are going to be the norm for the foreseeable future, and with that in mind, designers and manufacturers have answered the call by providing options that are tailored for different lifestyles and fashion tastes. Almost every mask below is on sale, so you can find one that fits your needs without overspending.

1. Multicolor 5-pack of Polyester Face Masks; $22 (56 percent off)

Home Essentials

This set of five polyester masks offers the protection you need in a range of colors, so you can coordinate with whatever outfit you're wearing.

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2. 3D Comfort Masks 5-Pack; $20 (25 percent off)

Brio

The breathable, stretchy fabric in these 3D masks makes them a comfortable option for daily use.

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3. Reusable Face Masks 2-pack; $15 (50 percent off)

Triple Grade

This cotton mask pack is washable and comfortable. Use the two as a matching set with your best friend or significant other, or keep the spare for laundry day.

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4. Active Masks 3-pack; $23 (14 percent off)

RipleyRader

Don’t let masks get in the way of staying active. These double-layer cotton masks are breathable but still protect against those airborne particles.

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5. Washable Protective Cotton Face Masks 2-pack; $13 (35 percent off)

Its All Good

Avoid the accidental nose-out look with this cotton mask that stays snug to your face.

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6. Washable 3D Masks 12-pack; $24 (44 percent off)

Elicto

With this 12-pack of protective masks, you can keep a few back-ups in your car and hand the rest out to friends and family who need them.

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7. Reusable Dust-Proof Mask with 5 Filters; $22 (45 percent off)

Triple Grade

This dust-proof mask can filter out 95 percent of germs and other particles, making it a great option for anyone working around smoke and debris all day, or even if you're just outside mowing the lawn.

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8. Reusable Fun Face Cover / Neck Gaiter (Flamingo); $20

Designer Face Covers

Channel some tropical energy with this flamingo fabric neck gaiter. The style of this covering resembles a bandana, which could save your ears and head from soreness from elastic loops. Other designs include a Bauhaus-inspired mask and this retro look.

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9. Seamless Bandana Mask; $8 (52 percent off)

Eargasm Earplugs

This seamless gaiter-style mask can be worn properly for protection and fashioned up into a headband once you're in the car or a safe space. Plus, having your hair out of your face will help you avoid touching your eyes, nose, and mouth before washing your hands.

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10. Two-Ply "Love" Face Masks 2-Pack; $18 (40 percent off)

Design Safe

These statement masks allow you to have a voice, even if your mouth is covered.

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11. Neoprene/Fleece Neck and Face Mask (Purple); $10 (66 percent off)

Its All Good

This mask will definitely come in handy once winter rolls around. It features a fleece neck, face, and ear covering to keep your mask secure and your face warm.

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Prices subject to change.

This article contains affiliate links to products selected by our editors. Mental Floss may receive a commission for purchases made through these links. If you haven't received your voucher or have a question about your order, contact the Mental Floss shop here.

Why Do We Say ‘Spill the Beans’?

This is a Greek tragedy.
This is a Greek tragedy.
anthony_taylor/iStock via Getty Images

Though superfans of The Office may claim otherwise, the phrase spill the beans did not originate when Kevin Malone dropped a massive bucket of chili at work during episode 26 of season five. In fact, people supposedly started talking about spilling the beans more than 2000 years ago.

According to Bloomsbury International, one voting method in ancient Greece involved (uncooked) beans. If you were voting yes on a certain matter, you’d place a white bean in the jar; if you were voting no, you’d use your black bean. The jar wasn’t transparent, and since the votes were meant to be kept secret until the final tally, someone who accidentally knocked it over mid-vote was literally spilling the beans—and figuratively spilling the beans about the results.

While we don’t know for sure that the phrase spill the beans really does date all the way back to ancient times, we do know that people have used the word spill to mean “divulge” at least since the 16th century. The Oxford English Dictionary’s earliest known reference of it is from a letter written by Spanish chronicler Antonio de Guevara sometime before his death in 1545 (the word spill appears in Edward Hellowes’s 1577 translation of the letter).

Writers started to pair spill with beans during the 20th century. The first known mention is from Thomas K. Holmes’s 1919 novel The Man From Tall Timber: “‘Mother certainly has spilled the beans!’ thought Stafford in vast amusement.”

In short, it’s still a mystery why people decided that beans were an ideal food to describe spilling secrets. As for whether you’re imagining hard, raw beans like the Greeks used or the tender, seasoned beans from Kevin Malone’s ill-fated chili, we’ll leave that up to you.

[h/t Bloomsbury International]