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The Quick 10: 10 Underground Cities

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As I mentioned the other day, we're headed to Seattle in October. As I was researching things to do, I came across the Seattle Underground Tour, which many of you said was pretty awesome. It made me wonder how many other cities out there have something similar. Here are a few of them.

1. Seattle. I'll start with Seattle, just in case you didn't read the post on Wednesday.
In 1889, a cabinet maker was heating some glue It boiled over when he wasn't looking and set fire to the wood chips below. Before you could say "Mrs. O'Leary," the fire spread across town and consumed most of the business district downtown - 25 entire blocks, to be exact. Rather than relocate, the citizens and government of Seattle just decided to regrade the city streets higher and build on top of all of the old stuff. These days, all of the "old stuff" can still be found underneath. It's been somewhat refurbished and made more structurally sound for touring purposes.

2. Portland, Oregon. The Shanghai Tunnels of Portland, AKA the Portland Underground, may have a pretty shady past. The tunnels connected a bunch of basements of business and bars in the Old Town/Chinatown district and are said to have been built to get goods from the docks to the businesses without clogging up the streets in town. But more than one source says the tunnels were used for other purposes: to kidnap (shanghai) people who got too drunk in the bars and then sell them into the slave trade, using the tunnels to get them to the docks and ship them out. It's never been proven, but Portland Underground Tours will give you a good idea of how it could have happened (they maintain that it absolutely did happen).

3. Atlanta. Underground Atlanta is a well-known shopping district now, but disappeared from the maps for many years. It was street-level back in the 1800s, but during the 1920s, concrete viaducts were built to accommodate the growing traffic flow of the busy city. The construction of the viaducts raised the streets a level and everything underneath was abandoned"¦ until the 1960s, when it was rediscovered. It's a fun shopping and entertainment district today, but if you keep your eyes peeled, you can still see remnants of the past: hand carved wooden panels, decorative brick, granite arches and marble accents.

4. Beijing. On the other side of the ocean, Beijing has its own underground city called Dixia Cheng. It was originally a bomb shelter, and is maintained as such, but it opened as a tourist attraction for several years as well. It's currently closed to tourists, but if you ever find yourself lucky enough to check it out, you'll see a silk factory that has taken up shop in one of the underground meeting rooms, signposts to major landmarks and murals with slogans like "Accumulate Grain."


5. Vegas. Sick of the neon and the showgirls? There's another side to Vegas, but you're not going to find a tour of it - and you probably don't want to. A maze of storm tunnels have been turned into makeshift living quarters for about 300 people. Most are just humble piles of blankets and belongings, but a few people have managed to almost make apartments out of the larger rooms that connect the storm drains.

6. The Magic Kingdom. Yep, there's a whole other level to the Happiest Place on Earth. The part you see is actually the first floor. The ground level is under your feet. It's where the cast members roam, how food and merchandise is brought into stores, and where the employee cafeterias, offices and break rooms are located. Disney built this first, then used the soil scooped out from the creation of the Seven Seas Lagoon to make the park that sits on top of it.


7. Chicago. It looks like Chicago could have an underground city of its own - or at least a mini one. In the late 1850s, residents of the Windy City were having issues with drainage and flooding because the city sat nearly even with Lake Michigan. The solution? To raise parts of the city up another four or five feet. And the real kicker was this: although the City of Chicago was paying for the street regrades, individual property and business owners were responsible for doing something about their own buildings. If you couldn't afford it, tough. i bet if you know where to look, there's plenty of interesting underground structures hidden just below the street.

8. Rome. You don't get much more ancient than this. The catacombs in Rome and the surrounding area are arguably the most famous ones in the world (see #9). At least 40 catacombs contain thousands of bodies that lie up to four stories below the ground. The oldest catacombs - St. Priscilla's - dates back to the late second century, but you'll find nine Popes in the largest and most popular catacombs, St. Callixtus.

9. Paris. Paris has it's own catacombs, but that's only part of what is known as Carrières de Paris - the quarries of Paris. There are more than 177 miles of tunnels and quarries under the streets of the City of Light, and they have become a hotbed of activity for artists known as cataphiles.


10. Burlington, Wiltshire, England. There's about 35 acres of city 100 feet below ground in Burlington. The 60 miles of roads were to carry the Prime Minister and his entire Cabinet in case of a Cold War emergency. It was build to keep up to 4,000 people alive for up to three months. It even included an underground lake. It was, of course, never used, and was actually put up for sale several years ago. One company, Octavian, bought a small piece of it to use to store 800,000 cases of wine. "It's a nice idea going from a red scare to red wine," the managing director of the company said.

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technology
Man Buys Two Metric Tons of LEGO Bricks; Sorts Them Via Machine Learning
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iStock // Ekaterina Minaeva

Jacques Mattheij made a small, but awesome, mistake. He went on eBay one evening and bid on a bunch of bulk LEGO brick auctions, then went to sleep. Upon waking, he discovered that he was the high bidder on many, and was now the proud owner of two tons of LEGO bricks. (This is about 4400 pounds.) He wrote, "[L]esson 1: if you win almost all bids you are bidding too high."

Mattheij had noticed that bulk, unsorted bricks sell for something like €10/kilogram, whereas sets are roughly €40/kg and rare parts go for up to €100/kg. Much of the value of the bricks is in their sorting. If he could reduce the entropy of these bins of unsorted bricks, he could make a tidy profit. While many people do this work by hand, the problem is enormous—just the kind of challenge for a computer. Mattheij writes:

There are 38000+ shapes and there are 100+ possible shades of color (you can roughly tell how old someone is by asking them what lego colors they remember from their youth).

In the following months, Mattheij built a proof-of-concept sorting system using, of course, LEGO. He broke the problem down into a series of sub-problems (including "feeding LEGO reliably from a hopper is surprisingly hard," one of those facts of nature that will stymie even the best system design). After tinkering with the prototype at length, he expanded the system to a surprisingly complex system of conveyer belts (powered by a home treadmill), various pieces of cabinetry, and "copious quantities of crazy glue."

Here's a video showing the current system running at low speed:

The key part of the system was running the bricks past a camera paired with a computer running a neural net-based image classifier. That allows the computer (when sufficiently trained on brick images) to recognize bricks and thus categorize them by color, shape, or other parameters. Remember that as bricks pass by, they can be in any orientation, can be dirty, can even be stuck to other pieces. So having a flexible software system is key to recognizing—in a fraction of a second—what a given brick is, in order to sort it out. When a match is found, a jet of compressed air pops the piece off the conveyer belt and into a waiting bin.

After much experimentation, Mattheij rewrote the software (several times in fact) to accomplish a variety of basic tasks. At its core, the system takes images from a webcam and feeds them to a neural network to do the classification. Of course, the neural net needs to be "trained" by showing it lots of images, and telling it what those images represent. Mattheij's breakthrough was allowing the machine to effectively train itself, with guidance: Running pieces through allows the system to take its own photos, make a guess, and build on that guess. As long as Mattheij corrects the incorrect guesses, he ends up with a decent (and self-reinforcing) corpus of training data. As the machine continues running, it can rack up more training, allowing it to recognize a broad variety of pieces on the fly.

Here's another video, focusing on how the pieces move on conveyer belts (running at slow speed so puny humans can follow). You can also see the air jets in action:

In an email interview, Mattheij told Mental Floss that the system currently sorts LEGO bricks into more than 50 categories. It can also be run in a color-sorting mode to bin the parts across 12 color groups. (Thus at present you'd likely do a two-pass sort on the bricks: once for shape, then a separate pass for color.) He continues to refine the system, with a focus on making its recognition abilities faster. At some point down the line, he plans to make the software portion open source. You're on your own as far as building conveyer belts, bins, and so forth.

Check out Mattheij's writeup in two parts for more information. It starts with an overview of the story, followed up with a deep dive on the software. He's also tweeting about the project (among other things). And if you look around a bit, you'll find bulk LEGO brick auctions online—it's definitely a thing!

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Health
200 Health Experts Call for Ban on Two Antibacterial Chemicals
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iStock

In September 2016, the U.S. Food and Drug Administration (FDA) issued a ban on antibacterial soap and body wash. But a large collective of scientists and medical professionals says the agency should have done more to stop the spread of harmful chemicals into our bodies and environment, most notably the antimicrobials triclosan and triclocarban. They published their recommendations in the journal Environmental Health Perspectives.

The 2016 report from the FDA concluded that 19 of the most commonly used antimicrobial ingredients are no more effective than ordinary soap and water, and forbade their use in soap and body wash.

"Customers may think added antimicrobials are a way to reduce infections, but in most products there is no evidence that they do," Ted Schettler, science director of the Science and Environmental Health Network, said in a statement.

Studies have shown that these chemicals may actually do more harm than good. They don't keep us from getting sick, but they can contribute to the development of antibiotic-resistant bacteria, also known as superbugs. Triclosan and triclocarban can also damage our hormones and immune systems.

And while they may no longer be appearing on our bathroom sinks or shower shelves, they're still all around us. They've leached into the environment from years of use. They're also still being added to a staggering array of consumer products, as companies create "antibacterial" clothing, toys, yoga mats, paint, food storage containers, electronics, doorknobs, and countertops.

The authors of the new consensus statement say it's time for that to stop.

"We must develop better alternatives and prevent unneeded exposures to antimicrobial chemicals," Rolf Haden of the University of Arizona said in the statement. Haden researches where mass-produced chemicals wind up in the environment.

The statement notes that many manufacturers have simply replaced the banned chemicals with others. "I was happy that the FDA finally acted to remove these chemicals from soaps," said Arlene Blum, executive director of the Green Science Policy Institute. "But I was dismayed to discover at my local drugstore that most products now contain substitutes that may be worse."

Blum, Haden, Schettler, and their colleagues "urge scientists, governments, chemical and product manufacturers, purchasing organizations, retailers, and consumers" to avoid antimicrobial chemicals outside of medical settings. "Where antimicrobials are necessary," they write, we should "use safer alternatives that are not persistent and pose no risk to humans or ecosystems."

They recommend that manufacturers label any products containing antimicrobial chemicals so that consumers can avoid them, and they call for further research into the impacts of these compounds on us and our planet.

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