May 31 – Anniversary of the Discovery of the Catacombs

Posted on May 24, 2014

On this date in 1578, some workers just outside of Rome, Italy, were digging up some pozzolano earth to be used to make cement. And they discovered something very cool. Or maybe very creepy!

The Catacombs.

The workers discovered a stairway going downward, underground, and opening out to a series of narrow rooms or galleries that had been carved out of rock.

And the creepy part is that these were burial galleries!

When the Catacombs were discovered by accident, there was some excitement, but nobody put the effort in to study them. But in 1593 a young man named Antonio Bosio decided that they were interesting – and important! - and he began to explore them.

He explored the Catacombs for more than 27 years! Basically, he explored them for the rest of his life.

Bosio found 30 more entrances – 30 more sets of stairs going underground. And he discovered that the chambers that were first found were connected to more and more – and more and more – narrow tunnels and galleries.

Some of the walls in some
catacombs were decorated
with paintings.

I read that, if you laid out all the branching galleries end to end, they would stretch the length of the country of Italy! (And yet all these lie just outside the city of Rome.) I also read that the estimate of the number of bodies buried in the Catacombs is about two million...Crazy, huh?!

The people buried in the Catacombs were Jews and (mostly) early Christians who lived in Rome. Apparently ancient Romans cremated their dead and kept the ashes in family tombs, but the Jews who lived in Rome followed the Jewish tradition of burial. Because the graves in Palestine were mostly tombs cut into rock, covered with slabs of stone, the Jews of Rome carved out similar rock tombs underground. And since early Christianity was considered a sect of Judaism, so did the early Christians.

Bosio ended up writing a book called Roma Sotterranea (Underground Rome), in which he carefully described many of the catacombs he had explored. Modern scholars are grateful that he did this, because some of the catacombs he had explored have since been destroyed.

Some of the catacombs are decorated with
artistically arranged bones.

Why rock?

Under Rome and the land surrounding Rome is a thick layer of tuff (sometimes called tufa). This volcanic rock is made from layers of ash spewed from volcanoes and washed down into low-lying areas. The ash is pressed together by additional layers of ash and soil, and it hardens into rock.

Although the tuff found in some places of the world is pretty brittle—even fragile—the tuff that is the bedrock of Rome is pretty strong. Many ancient and even modern Roman buildings have been built of blocks of tuff.

Still, I imagine that tuff is a little easier to carve into than some sorts of rock. It was probably ideal for creating rock graves—and that's why the catacombs were used for so long, by so many.

When Christianity became the official religion of Rome, in 380, various buildings and temples were torn down or changed to become churches, and burials began to be in more familiar churchyards and cemeteries. Eventually the catacombs were forgotten, their stairway-entrances buried—perhaps for a thousand years—until that accidental discovery on May 31, 1578.

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May 30 – Happy Birthday, Georg von Peuerbach

Posted on May 30, 2014

This Austrian astronomer and mathematician—born on this date in 1493—accomplished a lot of things in his fields. Two of those accomplishments were creating better, more accurate eclipse tables and sine tables than had been available before.
Why were they better and more accurate?

Obviously, Peuerbach was careful with his computations. But in his sine table he also used what people call Arabic numbers, Hindu-Arabic numbers, or (these days) just numbers: 0123456789. He was one of the first mathematicians to promote the use of Arabic numbers in trigonometry.

Detour: What is a sine table?                                                            
Trigonometry is the math of right-angled triangles. Sine is the ratio of one side of a triangle to another side (since there are three sides to every triangle, there are other trigonometric ratios such as cosine and tangent).               
Back before there were electronic calculators, mathematicians made tables so that people using sine and other ratios wouldn't have to stop what they were doing and calculate a long, involved division problem—they could instead just consult the correct table.                 
For centuries people have used sine and cosine, and trigonometry in general, in surveying (measuring altitudes and distances) and in navigation. Nowadays they continue to use sine and cosine in space flight, analyzing sound waves and TV signal transmission, GPS and cell phones, and compressing digital information to make things like JPEG files.                                                                                           

Why are Hindu-Arabic numbers used so widely now?

Once upon a time there were many number systems, from Roman numerals and Japanese numerals to Mayan numerals and the Abjad number system. But now one set of numerals has spread all over the world. We still see some other numerals as well—such as Roman numerals labeling the volumes of a book or distinguishing one King Henry from another—but the familiar 0123456789 has become the dominant system.

This telephone number pad
is from Egypt. The numerals
on the left are the Western
"Arabic numerals," and those on
the right are the Eastern "Arabic
numerals." Confusing, huh?
This system was developed between the 1st and 4th Centuries by Indian mathematicians. Persian mathematicians adopted and developed the system, and the system was spread largely by the Arab civilization, which was the center of learning in the Western world from around the 8th Century to the 1200s. The Italian scholar Fibonacci encountered them in North Africa and helped to make them known throughout Europe, through his work.

By the mid-1500s these numbers were in common use in Europe, but it took early adopters like Peuerbach to make it happen!

Okay, so why this system? Why did the Hindu-Arabic system win out over all those other systems?

It has two great things: Positional place value, and Zero.

The Hindu-Arabic system is not the ONLY system to ever have these great things, but it is one of the first to combine both. If you have ever seen a comparison of dates in Roman numerals and our (Arabic) numerals, you know that ours can be a space saver:

MCMLXIV – 1964

MMXVIII – 2018


(To learn more about Roman numerals, check out this earlier post.) 

Ours is a space saver because it has “positional” place value. A number 2 in the leftmost spot of a whole number is exactly that – 2 – but when it is in the second spot from the left, it represents 2 tens (20), and when it is one more spot away from the left, it represents 2 hundreds (200), and so forth.

And zero makes the whole place value system work, because if there are no “tens” in a number, you can plunk a zero in that spot and still make sense of the number. Without a zero as a placeholder, 105 and 15 would look like the same number!

So when you wish Georg von Peuerbach a happy birthday, also thank him for being an early adopter of our wonderful number system!

The Hindu-Arabic numerals did evolve and change from
ancient times to modern times.
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May 29 – Put a Pillow on Your Fridge Day

Posted on May 29, 2014

Is this really a thing?

Several websites talk about this holiday as if putting a pillow onto your refrigerator one day a year is something that a lot of people do. I have definitely never seen or heard of such a thing, myself – I wonder how widespread the custom really is!

If you, like me, don't know about the whole pillow-on-the-fridge thing, you are probably wondering why anyone would do such a thing. It turns out, it's supposed to bring people good luck and prosperity.

An old-fashioned larder.
Somehow, back in the mists of time, a custom got started of putting a cloth in the larder every May 29 for good fortune. That was back when people actually had larders – small rooms (or large cupboards) in which food was stored. These larders were located in the shadiest, coolest part of the house—but of course near the kitchen, and they were kept as cool and dry as possible so that food would keep as long as possible.

Nowadays, some of us are lucky enough to have walk-in pantries or at least large food-storage cupboards, but of course we all have refrigerators as well. Many of the things people used to store in a larder – vegetables and cheeses, meats and leftovers – we now store in the fridge. So somehow the custom of putting a cloth INTO the larder evolved into putting a pillow ONTO the refrigerator.

Are your customs based on superstitions?

A superstition is a belief that there will be some supernatural effect of wearing, saying, or doing certain things in a certain way. For example, a student might wear a “lucky” sweatshirt on test day, or an athlete might eat chicken before every game. Apparently basketball great Michael Jordan wore his University of North Carolina practice shorts under his Chicago Bulls uniform every game! In order to cover the UNC shorts, Jordan started wearing longer NBA shorts—and he inspired a style trend; now everybody wears longer shorts.

Basketball shorts before and after Michael Jordan.
Thank goodness for Michael Jordan!

This is pretty gross:
When I was a little girl, EVERYBODY
(yes, even me) had a rabbit's foot lucky
charm. You could feel the little bones and
toenails. Now it seems pretty horrifying!
Obviously, there is no evidence that a cloth in one's larder or a pillow on one's refrigerator on a particular day in May makes any difference in one's life. This is just a superstition. But a lot of things that start off as superstitions—things that people believed really WOULD bring good luck or ward off bad luck—become fun customs that people continue to do long after superstitious belief in their power has faded. (For example, colored eggs were supposed to protect the owner's health or bring good luck—but these days, most of us who color Easter eggs do it just for fun!)

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May 28 – Sierra Club Day

Posted on May 28, 2014

The Sierra Club is one of the oldest and largest environmental groups in the U.S., and its birthday is today!

The Sierra Club was started in California on this date in 1892 by conservationist John Muir. It started with 182 members, and it took sixteen years for the group to grow to 1,000 people – but now its membership is more than two million!

Explore! Enjoy! And protect the planet!

That's what the official website urges us to do.  And of course, when we say “protect the planet,” we pretty much mean protect the way the oceans, rivers, atmosphere, and climate have been for the past few thousand years, and protect the animals and plants alive today.

The planet itself – the solid inner core, liquid outer core, hot-rock mantle and rigid crust made up of various-sized plates – it'll be fine! It's pretty big, and it needs no protection from us paltry humans.

But the things we need to live and flourish – clean air and water, a reliable climate, healthy ecosystems of plants and animals and other organisms, beautiful natural spots and regions of wilderness – all of THAT is what conservationists want us to preserve and protect.

In addition to working on green politics and energy policies, and trying to lessen global climate change, the Sierra Club organizes lots of outdoor activities. Mountaineering and rock climbing are specialties, but hikes and float trips are also common Sierra Club activities. Another thing to consider is volunteer vacations. Families can help clean up or restore trails and wilderness instead of lolling on a beach or boat!

Hmm...hard physical labor while on vacation? Actually, the trips sound pretty amazing!

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May 27 – Happy Birthday to the “Mother of Modern Dance”

Posted on May 27, 2014

Although the world-famous dancer and choreographer Isadora Duncan was born in America – in my home state of California, actually – she lived most of her adult life in Europe and the Soviet Union.

Duncan (born on this date in 1877, according to some sources) grew up very poor, in a “broken home” (her parents divorced, so her mom raised her and her two brothers and sister). Her mom was a piano teacher who was passionate about the arts, and Isadora discovered an early passion, too, in dance. She began to teach “movement” to neighborhood children when she was just six years old. By the time she was ten, her classes had become pretty large, and she and her older sister dropped out of school to work teaching dance for pay.

When Duncan first went to Europe, she studied Greek mythology, and she fell in love with flowing tunics worn by the Ancient Greeks. She learned about the ancient rituals surrounding dance, and she developed a unique style that she carried into her own work as a dancer and choreographer.

For example, she often dressed like this when she danced:

At the time that Duncan was introducing dancing barefoot in loose, flowing tunics, everyone else was into rigid ballet technique, corseted costumes, and painful-to-wear pointe shoes. Duncan combined her love of Ancient Greece with Americans' love of freedom as she introduced natural movements such as skipping, plus “great strides, leaps and bounds, with lifted forehead and far-spread arms.” 

Duncan was a maverick off the dance floor, too, but she faced great tragedies in her life. She had three children, but they all died in childhood. Her husband was mentally ill and committed suicide. Isadora Duncan herself died earlier than she should have – at age 50 – when her long, flowing scarf tangled in the spokes of the automobile she rode in, and her neck was broken.

The world always loves a good, gossipy story, and Duncan's life allowed plenty of such stories. But the world mostly remembers her as a dancer who earned fame and acclaim in Europe, and as a pioneer whose work led to an entirely new, much freer form: modern dance.

To this day, there is a dance company
carrying on Duncan's work.
Here is a sample of some of this natural, modern movement. Note: this is a pretty old video, but I'm sure it was filmed decades after Duncan died.

This video clip, I believe, offers some very early motion picture footage of Duncan herself. 

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