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Illustration by Wesley Allsbrooke

Houdini's Greatest Trick: Debunking Medium Mina Crandon

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Illustration by Wesley Allsbrooke

By Robert Love

On July 23, 1924, Boston was suffering from a brutal heat wave. The evening temperature hovered in the high 80s when the famed magician Harry Houdini trudged up to the fourth floor séance room at 10 Lime Street. With him were O.D. Munn, editor of Scientific American, and an esteemed panel of scientists. They had come to witness the psychic feats of the nation’s most credible spirit medium, a pretty 36-year-old flapper with blue eyes and a bob.

Her name was Mina Crandon. Followers called her “Margery”; detractors knew her as the Blonde Witch of Lime Street. And she was renowned for conjuring the voice of her dead brother, Walter, whose spirit rapped out messages, tipped tables, and even sounded trumpets. Even by ghost standards, Walter was unfriendly, answering questions and quoting scripture in a gruff disembodied voice. Margery, by contrast, was charming and attractive—at least when she wasn’t showing off her most convincing psychic talent: extruding a slithery, viscous substance called “ectoplasm” from her orifices. Photos show this otherworldly substance flowing from her nose and ears, but mostly it emerged from beneath a sheer kimono like a string of entrails—an “ectomorphic hand” that Walter used to carry out his commands.

Today we remember the era’s jazz, speakeasies, and glitz, but the ’20s were also the zenith of America’s obsession with the spirit world. Reeling from losing an estimated 15 million people in the Great War and 21 million more to the Spanish-flu pandemic, people were searching for ways to connect with the dead. Spirit guides emerged to help the bereaved, usually for hefty fees. And as reputable magazines and newspapers increased their coverage of paranormal phenomena, mediums became rock stars. Margery herself had become a messiah to hundreds of thousands of Americans.

In the summer of 1924, Margery occupied the red-hot center in the raging national debate over Spiritualism, an 80-year-old religious movement that centered around the possibility of communicating with the dead. The most famous of its 14 million believers was Sir Arthur Conan Doyle, author of the Sherlock Holmes mysteries and a man of impeccable reputation. Witnessing a séance in his London home, he became convinced of Margery’s supernatural powers. Her refusal to be compensated for her miracles only added to her credibility. It wasn’t long before Doyle had recommended her to the editors of Scientific American, which was offering a $2,500 prize to the first medium who could verifiably demonstrate to its six-man investigative committee a “visual psychic manifestation.”

This was no fly-by-night group of spook hunters. Scientific American’s J. Malcolm Bird chaired the committee, which included psychologist William McDougall of Harvard, former MIT physicist Daniel Comstock, and two members of the Society of Psychical Research, Hereward Carrington and Walter Prince. Bird and Carrington had already examined Margery more than 20 times and were ready to hand over the money. The New York Times reported the development with a straight face: "'Margery' Passes All Psychic Tests Scientists Find No Trickery in Scores of Séances with Boston Medium."

But Houdini, who’d suggested creating the panel after Scientific American approached him to investigate Spiritualism, had yet to offer his approval. When he learned the committee was prepared to endorse Margery, he was outraged. Having already exposed the tricks of other celebrity mediums, Houdini was sure the committee was about to be duped once more. He canceled his shows and headed for Boston.

Don't Believe Your Eyes

Margery greeted the panel and took her seat within a three-sided Chinese screen, the lights dimmed. Soon enough, an eerie whistling filled the room. On cue, the spirit of Walter whispered his arrival, even touching Houdini on the inside of his right leg. After a break, he ordered an electric bell enclosed in a wooden box brought to Houdini’s feet. Then Walter levitated a megaphone and boomed: “Have Houdini tell me where to throw it.”

“Toward me,” Houdini said, and the megaphone flew through the air and crashed in front of him. That was just the beginning. Throughout the evening, Walter produced a sequence of metaphysical spectacles, ringing the bell box on command and tipping over the wooden screen.

Houdini had done his homework. He knew that Dr. Le Roi Crandon, Margery’s husband, always sat on her right. (A Harvard-educated surgeon, Crandon was her greatest promoter, often showing visitors nude photographs of his wife in séance delicté). Houdini also guessed correctly that he would be seated at her left in the circle, with hands joined, feet and legs touching. In preparation for the evening, Houdini wore a tight bandage under his right knee all day; it was so painful it made his skin tender to even the slightest touch. The heightened sensitivity paid off. He could feel Margery twist and flex in the dark as she moved her left ankle slightly to get to the bell box under the table. Later, he felt her shift again to tip the Chinese screen with her foot. The flying megaphone stumped Houdini for a few hours, but he eventually figured out that Margery had placed it on her head, dunce-cap-style, with a momentarily free hand. She then jerked her head in his direction to send it crashing to the floor.

“I’ve got her,” he said when the evening was over. “All fraud. Every bit of it. One more sitting and I will be ready to expose everything.”

A second séance at a Boston hotel featured a levitating table. Houdini reached out in the dark and found Margery’s head lifting the table from beneath. He again felt her legs move as she reached to ring the bell box. “The slickest ruse I ever detected,” Houdini said later, in something close to admiration.

But when he announced his findings to the committee, he was asked to hold off on a public denunciation. The committee was conflicted. When it refused to award the prize after several additional séances, the Spiritualists became enraged—as did the spirit. “Houdini, you goddamned son of a bitch,” Walter roared. “I put a curse on you now that will follow you every day for the rest of your short life.” Bird and Carrington, still firmly under Margery’s seductive spell, continued to report that she had supernatural powers. In October, Scientific American published an article that described the committee as hopelessly divided.

The dithering angered Houdini. In November, he published a pamphlet called Houdini Exposes the Tricks Used by the Boston Medium “Margery,” complete with drawings of how she produced her “manifestations.”

“She certainly was clever in her maneuvering to pull the wool over the eyes of the committeemen,” he said, admitting the ingenuity of her techniques as he debunked their metaphysical nature. Houdini’s pamphlet humiliated Margery, but he wasn’t done yet: The “scourge of Spiritualism” wanted to make the religion disappear. Before long, Houdini was reproducing Margery’s so-called miracles to great laughter in performances across the nation.

All Doubters Welcome

Margery didn’t get the Scientific American prize, but Houdini’s efforts didn’t slow her down. Dr. Crandon pushed his wife to continue holding séances, inviting all doubters to the room at 10 Lime Street. In 1925, the Harvard faculty formed an investigative team, which skeptically witnessed new manifestations of her talents, including a luminous jumping paper “doughnut.” One investigator reported that he’d witnessed Margery reaching beneath her dress and pulling out strands of fake ectoplasm, which appeared to be “butcher’s offal.”

Meanwhile, Margery’s supporters went on the offensive, threatening to beat Houdini to a pulp and rooting for his demise. The escape artist continued to defy death in his stage show—locked, bolted, or chained in coffins submerged in water or buried under six feet of sand. Each time, he escaped. But Walter, Margery’s angry spirit guide, knew better. In August 1926, the spectre proclaimed that the end was near: “Houdini will be gone by Halloween,” he said.

In fact, Houdini died in agony on the afternoon of October 31, 1926 from septic poisoning. Throughout his career, Houdini had offered his steely abs to anyone who cared to take a shot. But when a student from Montreal threw a punch before Houdini could tense up, the blow ruptured his appendix, leading to a fatal infection. Houdini had worked hard to debunk Margery, but in a strange twist of fate, it was Margery who had the last word.

Sir Arthur Conan Doyle lived on for four more years and died a believer. The author’s spirit appeared to Margery often as she soldiered on through the depths of the Great Depression and her own alcoholism, but Houdini’s debunking had taken its toll. By the time she died at her house on Lime Street in 1941, her reputation and the Spiritual movement were in tatters. One of Walter’s fingerprints turned out to be her dentist’s, and one of her greatest supporters, Malcolm Bird, admitted to helping produce Walter’s actions at séances. But the fascination with Margery remained. Even on her deathbed, a psychic researcher showed up, hoping for a confession—or at least a hint of how she pulled off her most famous tricks. “Why don’t you guess?” she laughed bitterly. It was clear that the Blonde Witch of Lime Street wasn’t done toying with them yet. “You’ll all be guessing—for the rest of your lives.”

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iStock // Ekaterina Minaeva
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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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