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In 1945 a Japanese Bomb Exploded in Oregon, Killing Six

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Image credit: Southern Oregon Visitors Association

In November 1944, fifty years before Predator drones swept on the scene, the Japanese military devised a low-tech method of dropping bombs on foreign soil that didn’t require pilots. All it took was balloons—specifically, 9,000 33-foot-diameter “balloon bombs,” or Fu-Gos, each carrying 35 pounds of explosives.

Released from Japanese shores, these balloons were designed to rise to 30,000 feet then ride the jet stream east, making their way toward the U.S. in about three days. At that point, an altimeter would trigger a reaction that would jettison the bombs, which would explode once they landed, whipping up fires and panic across the country.

That, at least, was the plan. The Japanese would soon learn that you should never place your hopes of winning a war in the hands of the wind. Only a few hundred of these balloons made it to the States, and even fewer exploded. Plus, apparently the Japanese hadn’t checked the weather: The balloons landed during a cold, damp winter, sparking only a few brush fires that didn’t do much damage. One balloon landing in Nevada was picked up by cowboys and turned into a hay tarp. In Montana, two lumberjacks stumbled across a balloon with Japanese markings and the undetonated bomb still attached. Seven fire balloons in total were turned in to the Army, and as sightings continued to pop up everywhere from Alaska to Texas to Iowa, Americans started wondering what was up.

In January 1945, Newsweek ran an article titled "Balloon Mystery." At that point, the U.S. Office of Censorship stepped in, asking that media outlets refrain from mentioning the balloons, lest this give the Japanese the impression their attack had been a success, which might encourage them to send more. So the media kept their mouths shut. The Japanese, figuring there was no way Americans could keep this big a secret, were forced to conclude that their balloons had failed, and discontinued their use. Nonetheless, Japanese propaganda broadcasts boasted that their balloons had caused huge fires, widespread mayhem, and death counts as high as 10,000.

Only one balloon bomb claimed any American lives, and it was more of a sad tragedy than a military triumph: Five kids and their pregnant Sunday school teacher, Elyse Mitchell, came across the balloon in Oregon during a picnic in the woods. As Mitchell’s husband explained, "[One of the kids] came over and told us that there was a white object near by. We went to investigate. It blew up and killed them all." Mrs. Mitchell, Joan Patzke (11), Dick Patzke (13), Eddie Engen (13), Jay Gifford (12), and Sherman Shoemaker (12) became the only World War II casualties in the continental U.S., although they were hardly the sort of PR coup that would buoy Japanese spirits.

After their death, the media blackout was lifted to make Americans aware of the threat. Parks were filled with posters depicting what the balloons looked like, and warnings to not mess with them.

At the end of the day, Japan’s balloon bombs boasted a kill rate of only .067 percent. It was a flop as far as secret weapons go, although the Japanese get points for creativity. And remnants of these balloon bombs still exist, with parts being found as recently as 1992. So if you spot a balloon in the woods, steer clear—and take a moment to appreciate the fact that you may be witnessing one of the best-kept secrets of World War II.


This wasn't the only attack on Oregon during World War II. In 1942 a Japanese pilot in a submarine-based floatplane tried to drop incendiary devices over the forests around the town of Brookings.

In 1988 the Chicago Tribune caught up with the pilot of that mission, Nobuo Fujita, who returned to Brookings several times after the war and became something of an honorary citizen. According to his 1997 New York Times obituary, he gave the local library $1,000 to buy books about Japan for children, "so that there wouldn't be another war" between the two countries.
As for Elyse Mitchell's husband, life was marred by another tragedy. After his wife's death, he remarried, became a missionary, and traveled to Vietnam. In 1962 he was taken captive by the Viet Cong and never heard from again.

Judy Dutton is a regular contributor to mental_floss magazine. For our current issue, she wrote "9 Weapons That Failed Spectacularly (and 1 That Possibly Didn't)."

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iStock // Ekaterina Minaeva
Man Buys Two Metric Tons of LEGO Bricks; Sorts Them Via Machine Learning
May 21, 2017
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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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Name the Author Based on the Character
May 23, 2017
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