Tag Archives: history

Every little star in the sky

An azimuth compass shows 360° starting with 0/360°at due North.

Who wants to talk about Ptolemy some more? I told you about how people back then thought Earth was at the center of the universe and all the stars and planets revolve around her. This is called the geocentric model. The geocentric model has the stars on a humongous sphere. Good ol’ Ptolemy calculated the positions of all the stars and planets in the sky. He mapped exactly their azimuth and altitude.

Imagine you’re standing outside on a clear night and can see all the way to the edge of the sky—no trees or buildings in the way. That’s Earth’s horizon (we usually don’t see the horizon unless we’re in a flat desert or a big lake or ocean). You’re standing in the middle of a big circle, the base of a big dome. Directly above your head is the zenith, the center of the dome above. You can use a compass to find the direction of a star’s position—that’s its azimuth.

Using a cross-staff to find a star’s altitude.

You’ll need another device to figure how high that star is from the horizon—you work out the angle with your eyeball being the center point, the horizon at zero and the zenith at 90 degrees. A cross-staff is something Ptolemy may have used. You sight along the staff and point it in the star’s direction. Move the crossbar until it touches the horizon at the bottom and the star at the top. The position of the crossbar on the staff marks the angle of the star’s altitude.

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In case you hadn’t remember’d—

(Originally posted Oct 25, 2013)

Happy St Crispin’s Day!

But we in it shall be remember’d;
We few, we happy few, we band of brothers;
For he to-day that sheds his blood with me
Shall be my brother; be he ne’er so vile,
This day shall gentle his condition:
And gentlemen in England now a-bed
Shall think themselves accursed they were not here,
And hold their manhoods cheap whiles any speaks
That fought with us upon Saint Crispin’s day.Spoken by Henry; from William Shakespeare’s Henry V, Act IV Scene 3

Gang, this beautiful language is our inheritance—a gift to us from people long gone. Here is the entire scene. More info here. If you saw the Queen Elizabeth movie that came out a few years ago, you’ll remember Cate Blanchett in armor giving a speech to her troops just before they battle the Spanish. I assumed the screenwriters had been inspired by the King Henry speech above. Silly me, I got it backwards—in fact it was Queen Bess’ speech that had inspired Shakespeare.

Charlemagne & Pope Leo III from yesterday

Here’s the painting I did yesterday. Still a bit rough; needs some tightening up. Charles’ right hand doesn’t look like it’s holding the hilt of that sword. I have to figure out how to mount my camera (phone) so it’s not in the way when I paint. I kept bumping into it.

Charlemagne & Pope Leo timelapse

Here’s a little painting—you can watch as it gets painted. https://www.instagram.com/p/B3-HCj-gCVs/

It’s an image for this post.  Enjoy!

Ptolemy—why not take Ptolemy?

Ptolemy showing his geocentric model of the universe. That’s Earth in the middle.

We’re coming up on the Middle Ages, everybody! The Roman Empire has become the Holy Roman Empire—we’re still working on creating individual countries out of the territories of various tribes. The Christian Church has become a stabilizing institution. With Charlemagne’s help, religious centers—like monasteries—are also places of learning. Alcuin of York (Charlemagne’s right-hand man) designed an easier-to-read way of writing using capital letters and small letters instead of ALL CAPS!

Life isn’t easy for regular peasants, which is most people. It’s hard to make a living on a farm. Some people head to the towns to learn a trade. Sanitation isn’t so great and the bubonic plague is always just around the corner. It will be centuries before anyone figures out that plague is carried by fleas.

It usually takes a long time for civilizations to accept new ideas. Even after Eratosthanes showed the Earth to be round, many people thought she was flat. Both educated and uneducated people believed that the Earth was the center of the universe and the Sun, planets and stars revolved around her. They thought of the universe as a giant sphere—a ball—with planets and stars stuck onto it. This sphere would be like clear glass. The word for this idea is geocentricgeo is a Greek word for Earth, centric means smack dab in the middle.

We get this idea from an astronomer named Ptolemy (TOE-leh-mee), who lived in Alexandria, Egypt (100-170 ad, we think). He improved on the basic geocentric idea. Ptolemy used math to place the stars in fixed positions on this big sphere. He observed that the planets didn’t stay fixed on the sphere, though, so they were called wandering stars and got their own smaller spheres that fit inside the big one. The Sun made its own orbit, a circle, called an ecliptic.

Here’s Billie Holiday singing “All of Me.”

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https://www.britannica.com/biography/Ptolemy
https://www.teachastronomy.com/textbook/The-Copernican-Revolution/Ptolemy-and-the-Geocentric-Model/

It’s better than bad, it’s good

There is a mention of an hourglass in a ship’s inventory in the 1300s.

When you need to know where you are at sea, this is what you have to go on.

At sea, it’s difficult to know exactly where you are. No landmarks. No way to tell how far you are from land. Sailors had to be creative. To figure out distance, they used time.

Sailors liked the hourglass because it isn’t as affected by a ship’s bouncing around on the waves as a water-clock would be—it still marks an hour accurately. Smaller sandglasses with less sand mark shorter periods of time. Sailors could judge how fast their ship were traveling by ‘casting the log.’ They had a length of line—heavy cord—with a piece of wood (the log) tied to its end, and knots tied in it at regular intervals. They’d throw the log into the sea and turn the glass at the same time. The log dragged behind and pulled the line with it. When the sand ran out, they’d nip the line and count how many knots had run out. Number of knots = distance traveled in a set space of time.

If you know how fast you’re traveling, you can make a guess how far you traveled in an hour or a day or a week. This is how the sailors used to calculate where they were on the ocean.

Casting the log is said to have been invented in the 1500s. The first evidence of a ship’s log-book is from the 1600s. This is a guess, but it seems to me that the log-book would have been originally a record of the ship’s speeds—that eventually became a record of any important events that happened aboard the ship. With time, ‘log-book’ got shortened to ‘log.’

Today, people who post regularly on the worldwide web refer to their sad ramblings as a ‘web-log’ or ‘blog’ for short. Spare a thought for us poor, attention-starved souls.

Here’s an excellent video about casting the log.

https://www.britannica.com/technology/log-nautical-instrument
https://en.wikipedia.org/wiki/Chip_log
https://www.archives.gov/research/military/logbooks/naval-deck-logs.html

The secret origin of “log in”

More about time and distance.

Hourglasses

An hourglass is a device that measures time. It’s two glass bulbs joined together by a skinny neck. There’s sand inside, so when you set the hourglass with the sand-filled bulb on top, the sand trickles through the neck into the empty bulb below. The hourglass maker put in exactly an hour’s worth of sand, so when the top bulb is empty, one hour has passed. The whole contraption is contained in a frame so it can be stood on either end.

Hourglassses are sometimes called ‘sand clocks,’ but they’re timers. Remember the early Egyptian water clocks? They were timers, too, until Ctesibius figured how to make clocks out of them.

Legend says that a French monk called Liutprand (Lee-UT-prond) invented the hourglass in the 8th century ad. There doesn’t seem to be solid evidence to support or deny that. Charlemagne is supposed to have owned a 12-hour hourglass—Liutprand was French, Charlemagne was French, so maybe there’s a connection? And I guess I’d have to admit that at 12 hours, that hourglass was a clock.

https://www.guinnessworldrecords.com/world-records/first-hourglass

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Julius Caesar painting exercise

I just got a clamp-on holder for my phone and wanted to try this—

Update: Sorry for any confusion if you visited here in the last hour. I couldn’t get the video to show up. I’ve since added a link to Instagram. I hope that works! Thanks for your patience.

 

May we be Frank?

Throughout this history I’ve been trying to keep it zippy. Not too many words. No excess verbiage. Avoid the chit-chat. Anyway…to do that I’ve had to shrink down some larger-than-life personalities into one or two paragraphs. Charlemagne—also known as Carolus Magnus, Karl der Grosse, Charles the Great—is one guy who can hardly be covered in a book, let alone a blog post. But I’ll give it a whack.

After the western half of the Roman Empire fell to barbarian invasion in ad 476, civilization and culture had a tough time of it. From the north and west, people who would later become the French, the Germans, the Spanish and the Italians all fought within the empire. People from the MidEast also wanted to take over the empire. This state of constant warfare lasted more than a couple of centuries. Forget about culture—nobody could relax long enough to create art or music. Then in the 600s one tribe, the Franks, started fighting better than everybody else and a dynasty was begun—a ruling family who set up some stability and order using military power. The Carolingian Dynasty started with Charles Martel, then his son Pepin, then Charlemagne. Charlemagne was a ruler who rode at the head of his army and whupped the other armies. He brought more than peace to what had been the Roman Empire—he encouraged the arts, education and literature.

Remember that Christianity was the empire’s official religion since Theodosius. Pope Leo III was Charlemagne’s biggest fan and had Charlemagne crowned the Holy Roman Emperor in ad 800. After that, Charlemagne began a program of standardizing many parts of the Holy Roman Empire’s way of doing things. He relied on his right-hand man Alcuin of York to make much of this happen. Alcuin was a gifted innovator—he came up with cultural inventions that are part of our culture today.

F’rinstance, Charlemagne noticed that churches throughout the empire would sing a particular hymn, but each church used a different tune. He decided they should all sing a hymn using the same tune for that hymn, so Alcuin invented musical notation. With a songbook you can read how a tune should be sung. Charlemagne thought that the Roman way of writing (ALL CAPS) used up too much space and was difficult to read, so Alcuin invented upper-case and lower-case letters, like what you’re reading here.

Here’s why I’m telling you about Charlemagne. He liked Little Dennis’ Anno Domini system, so Charlemagne made AD and BC the Holy Roman Empire’s official way of numbering the years.

Just as it still is today.

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The Venerable Bede

What about all those years before Jesus was born? Don’t they get numbered, too?

I thought that a derby and a brolly would make him look more English.

In ad 731, an English monk, the Venerable Bede, wrote the Ecclesiastical History of the English People. He used the Anno Domini numbering system to date the years when events happened. Bede is considered to be the father of English history. Ecclesiastical means having to do with the Christian Church.

Bede’s History (5 volumes!) included events that happened before Christ was born. He numbered those years going backwards, starting with the year 1 Before Christ (bc for short). We still use bc and ad to number years. Lately it’s become fashionable among fancy-pants academic types to call Before Christ ‘Before Common Era’ and Anno Domini ‘Common Era.’ We use bc and ad in this history to honor the achievements of Bede and Dionysius.

‘Venerable’ means ‘honored’ or ‘revered.’

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