Tag Archives: Western Civilization

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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How big was it?

The Roman Empire was so big, its belly-button had an echo.

As time went by, the Roman Empire grew bigger and bigger. How big? When it sat around the Mediterranean Sea, it SAT AROUND the Mediterranean Sea. It extended north into the British Isles; west as far as the coast of Spain; south to include Egypt and east as far as Mesopotamia. The space it took up was 2.2 million square miles. One hundred and twenty million people lived in the Roman Empire.

That’s huge. There weren’t cell phones, tv or radio for one end of the empire to instantly communicate with the other. You could send a letter, which had to be carried by someone walking or riding a horse. Managing such a big area—especially guarding the borders from Rome’s enemies—was really difficult. There were roads and bridges and waterways that needed to be built and maintained. It was becoming too much of a headache for just one emperor.

The Romans tried having more than one emperor at the same time, which sorta kinda worked for a while. By ad 285 the Emperor Diocletian decided it was too big and split the empire into two halves. The city of Rome continued to be the capital of the western half. Byzantium became the capital of the eastern half. Together they were still called The Roman Empire. Separately each half began to take on a distinct and different character.

https://www.ancient.eu/Western_Roman_Empire/
https://www.quora.com/How-big-was-the-Roman-Empire
http://reifshistoryclasses.weebly.com/the-beginning-of-the-byzantine-empire-map-activity.html

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Archimedes and his odometer

Archimedes was a Greek mathematician who specialized in measuring space. He was certain that there must be a way to accurately measure how much space is in a circle—area—or how much space is in a sphere or a cylinder—volume (he figured out how to measure volume when he noticed that a certain amount of water spilled out when he got into a bath tub). Archimedes was influenced by other great mathematicians, like Pythagorus and Euclid.

Archimedes invented many wonderful machines, like a screw for drawing up water, or catapults that were used to fight off invading navies. Although we don’t have his plans for it, Archimedes is said to have invented a way to measure distance. This machine is called an odometer.

Archimedes’ odometer operated on the idea that every time a wheel goes around, it travels its own circumference. The odometer adds up those circumferences and marks when the wheel has traveled a mile. In our last post, we showed how a standard Roman chariot wheel goes around 42 times to travel a mile.

We know about Archimedes’ odometer because the Roman military engineer Marcus Vitruvius Pollio (80–70 bc – 15 bc), or Vitruvius for short, wrote about it in his 10-volume book De Architectura. Engineers build stuff. As the Roman Empire expanded, the army took along a corps of engineers to build fortifications; siege engines; bridges; tunnels; aqueducts to provide water; and roads. These engineers did such a good job that you can still find Roman bridges, aqueducts and roads today.

Emperor Caesar Augustus wanted to know exactly how big the empire was and decreed that mile markers should be put up along the newly-built roads. Vitruvius decided to build Archimedes’ odometer to accurately measure the miles.

We only know what Vitruvius’ odometer looked like from a fanciful drawing. We don’t know exactly how it worked. Some people, including Leonardo da Vinci, have come up with some pretty good guesses about how it worked. You can see Leonardo’s drawings here—plus, you can even download plans if you’d like to build one yourself! Now that’s cool.

We do know that every time the chariot wheel goes completely around, it moves other gears. The other gears are set up to mark a mile at the 42nd revolution of the chariot wheel. The trick is gear ratio—meaning some gears are bigger, some gears have more teeth. If the gear on the drive shaft has only one tooth and the gear holding the marbles has 42, the marble-gear moves 1/42 of a revolution every time the chariot wheel goes completely around. At the 42nd revolution, a hole with a marble lines up with a hole underneath the gear and the marble drops into a bucket. Each dropped marble represents one mile traveled.

https://discoveringancienthistory.wordpress.com/2017/01/01/engineering-an-empire-roman-units-of-measurement-part-1-of-3/
http://www.leonardo-da-vinci-models.com/odometer.html
https://www.ancient.eu/Roman_Engineering/


http://www.archimedespalimpsest.org/about/history/archimedes.php

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Measuring long distances

The Romans were geniuses at organization. The way they organized their government and army/navy is how they could maintain such a huge empire. The Romans found that standardization really helped—from soldiers’ armor to the width of a chariot wheel to money to constructing roads.

Good roads are important to a maintain a huge empire, especially for moving armies quickly from one place to another. It’s vital to know exact distances, too, if you are planning a big march with thousands of soldiers. We know that one Roman mile is 1,000 passus—paces—or 5,000 gradus—steps. The problem is, it’s too easy to lose count of all those steps. How do you measure a mile and know for sure you didn’t lose count?

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The future!

Can you see into the future? Thinking in linear time allows us to think about the future. It’s not easy, of course. People do use a timeline to plan projects and life goals, so that they can make them happen. In fact, I’m using a timeline for this project—writing this history which I plan to make into a book. Do you think about what you’ll be doing in 5 years? Successful people plan for the future. Holy cow, I sound like I’m selling life insurance.

The Torah (what Christians call the Old Testament), with its timeline of many generations of Jews, was read by ordinary people and changed the way ordinary people think about time and themselves.

In the Torah, ordinary people became important. Religious stories of other cultures were about gods and goddesses. Mortal beings had supporting roles in those stories, like when the mortal Paris judged a goddess beauty contest, or the gods created Enkidu to hang out with the semi-divine Gilgamesh. You don’t get a sense that the gods and mortals have a destiny together, because the stories don’t talk about a future. On the other hand, the stories in the Torah are about ordinary mortals who share a past and future with one God. When ordinary mortals—everybody, us—see ourselves as part of a destiny, the way we think about ourselves is changed. A person with a future, a destiny, has free-will and the mindset to break free of a cycle. You can see how a person with the inheritance of generations of history—aligned with God’s—has more free-will than the person who lives only in a cycle, the now, the present.

Timelines

Thinking in linear time changes our brains. Do you like history? History lovers keep a timeline in their heads. My dad loves history. He was a handy guy to have around when I had history homework. You can give my dad a date in history and he’ll tell you all about what was going on in the world at the time, what people were likely wearing, what they ate, how they got around, who were the big political players. He taught me how to research, how to use a library. When I was awarded the contract to illustrate A Prairie Dog for the President, I phoned Pop who started giving me facts about Lewis & Clark—just off the top of his head. Don’t watch a historical movie with my dad—if they monkeyed with the research he’ll take it apart!

A timeline is a foundation you can build on. If you have a general idea where the big events are on a timeline, you can add new eras and dates in their proper places. A timeline is a fantastic tool for organizing the way you think.

Happy Father’s day!

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How he did it

Just to recap from the last couple of posts: First, Eratosthenes guessed the Earth was round like a ball. Second, he knew that at noon on the Summer solstice, the Sun shone directly overhead in the town of Syene, which was 5,000 stadia south of Eratosthenes.

Third, Eratosthenes guessed the Sun was really big—huge, even. He noticed that shadows cast by the Sun are all parallel, so all the Sun’s rays must be parallel, too. Parallel means 2 or more lines that never touch—they stay the same distance from each other. Think train tracks.

SO, Eratosthenes—in Alexandria, 5,000 stadia north of Syene—put a stick (like the gnomon of a sundial) in the ground and made sure it was plumb. That stick was pointing down to the center of the Earth. If Earth is round, the well in Syene and Eratosthenes’ stick won’t be parallel, right? They’ll be at an angle to each other. Eratosthenes didn’t know exactly how many degrees that angle was, but in Alexandria at noon on June 21st, his stick cast a shadow.

There weren’t any shadows in Syene, because the Sun was directly overhead. He measured the stick, he measured the shadow, and used those measurements to draw an angle. The angle turned out to be a little over 7 degrees, or 1/50 of a circle.

Eratosthenes knew the distance from Alexandria to Syene was 5,000 stadia. He multiplied 5,000 by 50 to get the circumference of the Earth—250,000 stadia. In modern measurements that works out to be 28,738.418 miles or 46,250 kilometers.

The actual polar circumference of Earth is about 24,860 miles or just a bit over 40 thousand kilometers. The stadion Eratosthenes used may have been a little different from the standard unit. But even today, right now, if you search the internet for the circumference of the Earth, you won’t get just one answer.

Eratosthenes was a genius who used what he knew and observed, along with what he guessed at, to calculate something that no one knew—and he did it pretty accurately.

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Plumb

A plumb line or plumb bob.

Last post I rattled on about how the well at Syene was plumb.

‘Plumb’ means straight up-and-down. Builders used to use a plumb line—a string with a weight tied onto it—to check that their walls were straight up-and-down. A plumb line will always point to the center of the Earth. Nowadays they use a spirit level. Builders who dug wells made sure that the hole they dug was plumb—pointing directly toward the Earth’s center.

Why was it so important to Eratosthenes that the well at Syene (a town located on the Tropic of Cancer) was pointing directly at the Earth’s center at noon on June 21st—the Summer solstice?

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Eratosthenes


Head-Librarian Eratosthenes explains to a student how to laminate a dust jacket.

In an earlier post, I hinted about how over 2,000 years ago somebody calculated the circumference (how big around) of the Earth. This guy did it using only a well, a protractor and a stick (okay, maybe instead of a stick he used a column, but you could use a stick and get the same result).

I’m talking about Eratosthenes, the head librarian at the Great Library of Alexandria. Alexandria is an ancient city in Egypt, located where the Nile River flows into the Mediterranean Sea. Many scholars lived in Alexandria—like Ctesibius, who perfected the water-clock.

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