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The Origin of Air Conditioning

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Conceptually speaking, air conditioning has been around since the first primitive humans ducked into cool, damp caves to take refuge from summer heat. But aside from fans of various shapes and sizes, the technology of temperature control didn't progress beyond the stone age until the 1830s. That's when John Gorrie, a doctor from Florida, decided to do something about the stifling heat in his hospital, which he reasoned wasn't doing his malaria and yellow fever infected patients much good. In response, he created a simple contraption that was little more than a fan that blew over a bucket full of ice—and though it was mighty inefficient, it worked.

A more complex device was rigged up in the bedroom of dying president James Garfield in 1881. Naval engineers constructed a kind of box filled with ice water-soaked rags. A fan blew hot air overhead, forcing the cool air to stay low to the floor, where the ailing president's bed was. Half a million pounds of ice and two months later, the president was dead, though the engineers had succeeded in lowering the room's temperature an average of twenty degrees during that time.

But those were experiments, not the norm. Refrigeration first came into common use in some large cities during the late 1800s, typically piped from a central cooling station to meat lockers, keg rooms and even bank vaults where important documents were stored. "Manufactured air," as it was known, was primarily an industrial-use phenomenon until the turn of the century, when men like Willis Carrier, an engineer and air conditioning pioneer, began to experiment with systems practical for use in commercial and residential spaces. The key was precise control of the temperature-humidity relationship in the air, achieved by a series of chilled coils that both lowered temperature and the moisture level. His invention, built for the Brooklyn-based Sackett-Wilhelms Lithographing and Publishing Company, was called the "Apparatus for Treating Air," and it kick-started a revolution.

gates-castle.jpgSuddenly cooled air didn't have to come from a centrally-located supply; any business with enough money could have their own local system. Schools, hospitals, printing plants and textile manufacturers lined up to have air conditioners installed (as well as one wealthy private citizen, Charles Gates of Minneapolis, the first person to have his home—pictured at left—air-conditioned). The thing stopping Carrier's units from going into every home in America, however, was their gigantic size. Further, the potential danger of the toxic ammonia they used as coolant didn't help. In 1922, however, Carrier solved those problems by replacing the ammonia with the relatively safe chemical dielene, and added a compressor to the systems, which reduced their size and expense.

Soon the inventions were popping up in movie theaters all over the country, which became refuges for sweltering cineastes during the summers. Before long, air conditioning was debuting in office buildings, department stores and in fancy trains everywhere. World War II slowed things down a bit since resources were scarce, but when the troops came home and embraced the suburban American dream, many of them wanted that dream air conditioned. Within a few years, window units began selling like hotcakes: from just 74,000 in 1948 to over a million in 1953.

This article was written by Ransom Riggs and excerpted from the mental_floss book In the Beginning: The Origins of Everything. You can pick up a copy in our store.
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iStock // Ekaterina Minaeva
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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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Why Your iPhone Doesn't Always Show You the 'Decline Call' Button
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When you get an incoming call to your iPhone, the options that light up your screen aren't always the same. Sometimes you have the option to decline a call, and sometimes you only see a slider that allows you to answer, without an option to send the caller straight to voicemail. Why the difference?

A while back, Business Insider tracked down the answer to this conundrum of modern communication, and the answer turns out to be fairly simple.

If you get a call while your phone is locked, you’ll see the "slide to answer" button. In order to decline the call, you have to double-tap the power button on the top of the phone.

If your phone is unlocked, however, the screen that appears during an incoming call is different. You’ll see the two buttons, "accept" or "decline."

Either way, you get the options to set a reminder to call that person back or to immediately send them a text message. ("Dad, stop calling me at work, it’s 9 a.m.!")

[h/t Business Insider]

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