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physics.ox.ac.uk/Erin McCarthy

What’s the World’s Longest Running Science Experiment?

physics.ox.ac.uk/Erin McCarthy
physics.ox.ac.uk/Erin McCarthy

Between our look at the longest prison sentences the other day and the 69-year-old pitch drop experiment finally getting caught on camera last month, reader Justin got curious and wrote in to ask, “What’s the longest experiment that scientists have filled their decades or lifetimes with?”

While the pitch drop gets the nod for longest uninterrupted duration, there are at least two projects that started before it and keep going today, but have had some stops and starts along the way. The older of the two, and grand champion for years-in-progress, is the Oxford Electric Bell, a.k.a. the Clarendon Dry Pile.

The bell, as the name suggests, is an experimental electric bell kept at the University of Oxford’s Clarendon Library. It was built by Watkin and Hill, an instrument-making firm in London, and purchased by Robert Walker, a professor at Oxford. In 1840, he set it ringing. Today the bell still tolls. 

The bell is actually two metal bells, with a metal clapper set between them. The clapper is powered by two “dry piles,” an early form of battery.  Dry piles were normally composed of alternating strips of metal foil and paper—sometimes hundreds or thousands of layers thick—like electric club sandwiches. A variety of metals could be used, but Watkin and Hill left no record of what their piles were made of. 

Scientists are eager to find out just how long the mystery battery can go, and then open it up and find out what it's made of, but the whole thing is a bit of a waiting game. Whatever its makers used, the device has some staying power. Guinness World Records called the bell’s dry piles the “world’s most durable battery,” and for one hundred and seventy three years, minus occasional interruptions, the bell has been ringing. 

The clapper oscillates between the two bells at a usual frequency of 2Hz, or two cycles per second, depending on the weather. High humidity can cause the clapper’s movement to slow and even stop, but when the humidity drops the bell can begin again without external intervention. As the clapper strikes and rings one bell, the corresponding dry pile charges and electrostatically repels it. The clapper then swings toward the other bell, and the same thing happens. 

Because there’s just little bits of energy being discharged through the process, the drain on the battery—whatever it's made of—is very small, so it can happen again and again and again, causing a continuous ring. If we fudge a little and say that the clapper has had a 2Hz frequency for the entire 173 years, that means it’s made a whopping 10,911,456,000 strikes against those bells. 

Eventually, the electrochemical energy of the dry cells will be exhausted and the bell will go quiet. Not knowing what powers the contraption, though, no one is sure when that will happen, and silence instead could come when the clapper or one of the bells wears out. Not that anyone can hear it, anyway: To keep the patrons of the Clarendon Library from going mad from the noise, the bell is kept encased in sound-damping glass. 

The second longest-running experiment is an experimental clock (called the Beverly Clock) in New Zealand that's been ticking since 1864 without needing to be wound, and is driven by variations in atmospheric pressure and temperature.

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Big Questions
Why Does the Queen Have Two Birthdays?
CHRIS JACKSON, AFP/Getty Images
CHRIS JACKSON, AFP/Getty Images

On April 21, Her Majesty Queen Elizabeth II will turn 92 years old. To mark the occasion, there are usually a series of gun salutes around London: a 41 gun salute in Hyde Park, a 21 gun salute in Windsor Great Park, and a 62 gun salute at the Tower of London. For the most part, the monarch celebrates her big day privately. But on June 9, 2018, Her Majesty will parade through London as part of an opulent birthday celebration known as Trooping the Colour.

Queen Elizabeth, like many British monarchs before her, has two birthdays: the actual anniversary of the day she was born, and a separate day that is labeled her "official" birthday (usually the second Saturday in June). Why? Because April 21 is usually too cold for a proper parade.

The tradition started in 1748, with King George II, who had the misfortune of being born in chilly November. Rather than have his subjects risk catching colds, he combined his birthday celebration with the Trooping the Colour.

The parade itself had been part of British culture for almost a century by that time. At first it was strictly a military event, at which regiments displayed their flags—or "colours"—so that soldiers could familiarize themselves. But George was known as a formidable general after having led troops at the Battle of Dettingen in 1743, so the military celebration seemed a fitting occasion onto which to graft his warm-weather birthday. Edward VII, who also had a November birthday, was the first to standardize the June Trooping the Colour and launched a tradition of a monarchical review of the troops that drew crowds of onlookers.

Even now, the date of the "official" birthday varies year to year. For the first seven years of her reign, Elizabeth II held her official birthday on a Thursday but has since switched over to Saturdays. And while the date is tied to the Trooping the Colour in the UK, Commonwealth nations around the world have their own criteria, which generally involve recognizing it as a public holiday.

Australia started recognizing an official birthday back in 1788, and all the provinces (save one) observe the Queen's Birthday on the second Monday in June, with Western Australia holding its celebrations on the last Monday of September or the first Monday of October.

In Canada, the official birthday has been set to align with the actual birth date of Queen Victoria—May 24, 1819—since 1845, and as such they celebrate so-called Victoria Day on May 24 or the Monday before.

In New Zealand, it's the first Monday in June, and in the Falkland Islands the actual day of the Queen's birth is celebrated publicly.

All in all, just another reason it's great to be Queen.

Have you got a Big Question you'd like us to answer? If so, let us know by emailing us at bigquestions@mentalfloss.com.

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Big Questions
What Is the Meaning Behind "420"?
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iStock

Whether or not you’re a marijuana enthusiast, you’re probably aware that today is an unofficial holiday for those who are. April 20—4/20—is a day when pot smokers around the world come together to, well, smoke pot. Others use the day to push for legalization, holding marches and rallies.

But why the code 420? There are a lot of theories as to why that particular number was chosen, but most of them are wrong. You may have heard that 420 is police code for possession, or maybe it’s the penal code for marijuana use. Both are false. There is a California Senate Bill 420 that refers to the use of medical marijuana, but the bill was named for the code, not the other way around.

As far as anyone can tell, the phrase started with a bunch of high school students. Back in 1971, a group of kids at San Rafael High School in San Rafael, California, got in the habit of meeting at 4:20 to smoke after school. When they’d see each other in the hallways during the day, their shorthand was “420 Louis,” meaning, “Let’s meet at the Louis Pasteur statue at 4:20 to smoke.”

Somehow, the phrase caught on—and when the Grateful Dead eventually picked it up, "420" spread through the greater community like wildfire. What began as a silly code passed between classes is now a worldwide event for smokers and legalization activists everywhere—not a bad accomplishment for a bunch of high school stoners.

Have you got a Big Question you'd like us to answer? If so, let us know by emailing us at bigquestions@mentalfloss.com.

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