Why Does the Leaning Tower of Pisa Lean?

iStock
iStock

In 1172, Donna Berta di Bernardo donated 60 silver coins to the local cathedral for the purchase of stones to be used in the base of a new bell tower.

The next year, construction on the tower began and almost immediately there were problems. The tower site sat on soft ground composed mostly of clay, fine sand, and shells (the city sits between the Arno and the Serchio rivers). By the time the builders finished the second floor in 1178, the tower was beginning to lean.

Soon, construction was halted for almost 100 years, as Pisa fought wars against Genoa, Lucca, and Florence. This may have been a lucky break, as modern analysis says that the tower definitely would have toppled had construction continued without time for the soil to settle.

When work on the tower resumed again, it was leaning 0.2 degrees north of vertical, but by the time the workers started on the seventh floor, the tower was tilting one degree south. Around this time, construction stopped again for unknown reasons.

DON'T LEAN ON ME

Over the next century, construction continued intermittently.

The tower’s lean gained another 1.6 degrees. To counteract the lean, the builders made the remaining floors taller on the south side of the tower. But the weight of the additional floors only made the foundation sink further, making the lean worse. Having done what they could, the builders finished up and officially completed the tower around 1370.

Since the tower’s completion, engineers and architects from all over the world have monitored the lean and tried to correct it. These attempts have involved adding grout to the foundation masonry, wrapping plastic-coated steel pieces around the tower up to the second floor, pouring a concrete ring around the base of the tower, laying lead counterweights to the north side, installing anchored cable counterweights, and extracting soil from underneath the north side.

After the removal of more than 70 metric tons of soil in 2008, engineers announced that the Tower had been stabilized enough that it had stopped moving for the first time since construction began. Its lean is now only about four degrees (prior to the all the restoration attempts, the lean was 5.5 degrees), or about 13 feet past perfectly vertical. The Leaning Tower of Pisa should be stable for at least the next 200 years.

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

Does the Full Moon Really Make People Act Crazy?

iStock.com/voraorn
iStock.com/voraorn

Along with Mercury in retrograde, the full moon is a pretty popular scapegoat for bad luck and bizarre behavior. Encounter someone acting strangely? Blame it on the lunar phases! It's said that crime rates increase and emergency rooms are much busier during the full moon (though a 2004 study debunked this claim). Plus, there's that whole werewolf thing. Why would this be? The reasoning is that the Moon, which affects the ocean's tides, probably exerts a similar effect on us, because the human body is made mostly of water.

This belief that the Moon influences behavior is so widely held—reportedly, even 80 percent of nurses and 64 percent of doctors think it's true, according to a 1987 paper published in the Journal of Emergency Medicine [PDF]—that in 2012 a team of researchers at Université Laval's School of Psychology in Canada decided to find out if mental illness and the phases of the Moon are linked [PDF].

To test the theory, the researchers evaluated 771 patients who visited emergency rooms at two hospitals in Montreal between March 2005 and April 2008. The patients chosen complained of chest pains, which doctors could not determine a medical cause for the pains. Many of the patients suffered from panic attacks, anxiety and mood disorders, or suicidal thoughts.

When the researchers compared the time of the visits to the phases of the Moon, they found that there was no link between the incidence of psychological problems and the four lunar phases, with one exception—in the last lunar quarter, anxiety disorders were 32 percent less frequent. "This may be coincidental or due to factors we did not take into account," Dr. Geneviève Belleville, who directed the team of researchers, said. "But one thing is certain: we observed no full-moon or new-moon effect on psychological problems."

So rest easy (or maybe not): If people seem to act crazy during the full Moon, their behavior is likely pretty similar during the rest of the lunar cycle as well.

This story was updated in 2019.

What's the Difference Between a Rabbit and a Hare?

iStock.com/Carmen Romero
iStock.com/Carmen Romero

Hippity, hoppity, Easter's on its way—and so is the eponymous Easter bunny. But aside from being a magical, candy-carrying creature, what exactly is Peter Cottontail: bunny, rabbit, or hare? Or are they all just synonyms for the same adorable animal?

In case you've been getting your fluffy, long-eared mammals mixed up, we've traveled down the rabbit hole to set the record straight. Although rabbits and hares belong to the same grass-munching family—called Leporidae—they're entirely different species with unique characteristics. It would be like comparing sheep and goats, geneticist Steven Lukefahr of Texas A&M University told National Geographic.

If you aren't sure which animal has been hopping around and helping themselves to the goodies in your vegetable garden, take a closer look at their ears. In general, hares have longer ears and larger bodies than rabbits. Rabbits also tend to be more social creatures, while hares prefer to keep to themselves.

As for the baby animals, they go by different names as well. Baby hares are called leverets, while newborn rabbits are called kittens or kits. So where exactly do bunnies fit into this narrative? Originally, the word bunny was used as a term of endearment for a young girl, but its meaning has evolved over time. Bunny is now a cutesy, childlike way to refer to both rabbits and hares—although it's more commonly associated with rabbits these days. With that said, the Easter bunny is usually depicted as a rabbit, but the tradition is thought to have originated with German immigrants who brought their legend of an egg-laying hare called "Osterhase" to America.

In other ambiguous animal news, the case of Bugs Bunny is a little more complicated. According to scientist and YouTuber Nick Uhas, the character's long ears, fast speed, and solitary nature seem to suggest he's a hare. However, in the cartoon, Bugs is shown burrowing underground, which doesn't jive with the fact that hares—unlike most rabbits—live aboveground. "We can draw the conclusion that Bugs may be a rabbit with hare-like behavior or a hare with rabbit nesting habits," Uhas says.

The conversation gets even more confusing when you throw jackrabbits into the mix, which aren't actually rabbits at all. Jackrabbits are various species of large hare that are native to western North America; the name itself is a shortened version of "jackass rabbit," which refers to the fact that the animal's ears look a little like a donkey's.

A jackrabbit
Connor Mah, Flickr // CC BY-SA 2.0

As Mark Twain once famously wrote about the creature, "He is just like any other rabbit, except that he is from one-third to twice as large, has longer legs in proportion to his size, and has the most preposterous ears that ever were mounted on any creature but the jackass." (Fun fact: Black-tailed jackrabbits' extra-long ears actually help them stay cool in the desert. The blood vessels in their ears enlarge when it gets hot, causing blood to flow to their ears and ridding their bodies of excess heat.)

Rabbits, hares, and jackrabbits all have one thing in common, though: They love a good salad. So if you happen across one of these hopping creatures, give them some grass or weeds—and skip the carrots. Bugs Bunny may have loved the orange vegetable, but most hares and rabbits would prefer leafy greens.

Have you got a Big Question you'd like us to answer? If so, send it to bigquestions@mentalfloss.com.

SECTIONS

arrow
LIVE SMARTER