Tag Archives: time

Oh, What A Beautiful Ante Meridiem!

The first known use of ‘ante meridiem’ was in 1563. It’s from Latin: ‘meridiem’ means midday or noon. ‘Ante’ means before and ‘post’ means after. So ante meridiem or a.m. is before noon—the hours between midnight and noon. Post meridiem or p.m. is afternoon—the hours between noon and midnight.

A.M. and p.m. are used to describe hours on a 12-hour clock. 10:15 a.m. means 10:15 in the morning; 10:15 p.m. means 10:15 at night. In the military and in Europe, they use a 24-hour clock, so 13:00 means 1:00 p.m.

‘Meridian’ is a different word with 2 meanings. The first meaning is to make an adjective out of meridiem. To say, “She’s wearing an anti-meridian dress” means she’s wearing a dress suitable for the morning. Nobody talks like that nowadays.

Ooooooh—I just gotta paint her in a blaze of yellow and orange!

The second meaning is to describe a line of longitude. The Prime Meridian is Point Zero of east or west. It’s only ad 1563 in this history so we have to wait 200 years before somebody figures out longitude—and where in the world the Prime Meridian is located…

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https://www.merriam-webster.com/dictionary/ante%20meridiem

Ante meridiem or antemeridian?

Why 18?

According to inventory records, the Portuguese navigator Ferdinand Magellan had 18 hourglasses on each of his ships during his circumnavigation of the globe in 1522. I’ve read this fact in more than one source, but no one tells us why eighteen. Multiple hourglasses would allow you to check one against another for accuracy, but 18 seems like a lot for that purpose. Were all 18 used at the same time? You need only one sandglass to cast a log—and that sandglass would count minutes, not a whole hour.

It seems Magellan used the hourglasses mainly for keeping track of time. But why did he need 18 of them?

If anyone can tell me I’ll draw you a picture.

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Are we there yet?

Columbus had a feeling his crew would start getting antsy, so he kept 2 logs. A captain’s log is a daily record of data: ship’s speeds, changes in course, weather and other news. In one secret log Columbus was honest—he wrote the actual distances they had come each day (as far as he could tell). In the second log, Columbus wrote that they hadn’t come very far at all. He added some potty stops they hadn’t taken. That’s the log he showed his crew. He wanted them to not be upset that the voyage was taking so long.

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The amazing fantastic clock of Piazza San Marco

In 1493, the Venetian Republic commissioned the clockmaker Giovan Paolo Rainieri, from the town of Reggio Emilia, to design and build a clock. This clock would be big and beautiful and expensive—a tower would be designed and built on Saint Mark’s Plaza to house it. It would face the lagoon and the sea beyond, so the whole world could see how prosperous was Venice.

If you visit Venice you can see the Rainieri clock. Its face is decorated in gold and lapis lazuli (a mineral you make blue out of—blue paint ain’t cheap); the hand tells what hour it is and the current zodiac sign; above the clock is a statue of the Virgin Mary and Baby Jesus (made of gilded copper); twice a year a mechanical angel and three wise men parade in front of Mary and tip their crowns to her; above Mary is the lion of Saint Mark with his paw on the Gospel (the statue of the praying doge isn’t there anymore); and at the top, every hour two bronze giants ring an enormous bell with their hammers.

The entire contraption from top to bottom used a verge and foliot escapement to regulate the gears.

https://www.atlasobscura.com/places/torre-dell-orologio-venice-clock-tower
https://en.wikipedia.org/wiki/St_Mark%27s_Clock

https://en.wikipedia.org/wiki/St_Mark%27s_Clocktower

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How to slow down a clock

How did they do it?

Those medieval clock-designers came up with a system to slow down the unwinding. First, they attached a gear around the drive-shaft that meshed with a couple of other gears. As you saw with Archimedes’ odometer, the ratio of gear sizes and number of teeth-per-gear can control how fast one gear turns another gear.

That still wasn’t slow enough, though. You want a clock to operate for at least 24 hours before you have to wind it again. How can you make that unwinding even slower?

The answer: an invention called an escapement. An escapement is a mechanical device that interferes with the gear. It actually stops the gear’s movement for a fraction of a second, then lets go for a fraction of a second, stops it, lets go, stops it, lets go, stops it, lets go. The first escapement was called the verge and foliot. The verge is a second shaft (not the drive-shaft) with two paddles, or pallets, set at 90 degrees to each other. These pallets interact with a saw-toothed gear which is powered by the drive shaft. As the drive-shaft turns the saw-toothed gear, one pallet stops the gear for a moment until the other pallet is pushed aside.

This stop-and-let-go motion is controlled even further by a bar at the top of the verge shaft, called the foliot. The foliot has a weight hung on each end so that inertia (the weights’ unwillingness to move) slows down oscillation of the verge-shaft. You can control how fast the foliot swings back and forth by moving the weights closer or farther from the center.

https://aapt.scitation.org/doi/10.1119/1.3479712




https://www.mpoweruk.com/timekeepers.htm
https://www.uh.edu/engines/epi1506.htm

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Mechanical clocks

Sometime in the 1200s mechanical clocks began being designed and built. When I say mechanical, I mean there are several moving parts in the design. We’ve already seen sundials and water clocks and hourglasses. Water clocks and hourglasses use the release of energy to tell time, as water or sand run out of one container into another. The mechanical clock is different—it uses the release of energy to make it run but has a system of gears and stops to control that energy.

Like those older clocks, medieval mechanical clocks use gravity to supply their energy. A weight is tied to a long rope that is wound around a drive-shaft. When you let go of the weight, the rope unwinds and turns the shaft. The drive-shaft has an arrow attached at its end to point to the hour on a circular clock face. So far, so good—but the drive-shaft will turn really fast for a few seconds, the arrow will whiz around the clock face and then you’d have to wind the rope around again. You still wouldn’t know what time it is. What you need for a clock is a slo-o-o-ow release of energy. How can you slow down the unwinding of that rope?

Meanwhile, in Persia—

With only a jug of wine, a loaf of bread and thousands of calculations, Omar Khayyám works out a new calendar

ad1075. In Persia, using the Hindu-Arabic decimal system, Omar Khayyam introduced a new calendar. The length of the year was measured as 365.24219858156 days and is very accurate. It didn’t catch on in the West.

https://www.britannica.com/biography/Omar-Khayyam-Persian-poet-and-astronomer

Omar Khayyam


https://www.timeanddate.com/calendar/persian-calendar.html

Maimonides, Maimonides, there’s no one like Maimonides

Rabbi Moshe ben Maimon, or RAMBAM to his pals

Happy Hanukkah! It seems like a good time to post about Maimonides and Anno Mundi, or ‘in the year of the world’ in Latin.

Maimonides was a doctor, theologian, philosopher and legal scholar who studied the Hebrew Bible—what Christians call the Old Testament. He lived near Cairo, Egypt in the ad 1100s.

If you do any Bible study you’ll have realized that the Bible isn’t one book but a library of books. What makes Bible study challenging is trying to keep all the stories, laws, wisdom and poetry organized in your head.

Maimonides thought it would be a great idea to create a guide for studying the Bible. He focused on the 5 Books of Law, the Torah. These are Genesis, Exodus, Leviticus, Numbers and Deuteronomy. As he wrote his guide, the Mishneh Torah, he found that he needed a chronology—a timeline of the events that happened in those books. Maimonides used the list of generations of people found in Genesis and Numbers to work backward to calculate when the world was created. That exact date of October 7, 3761 bc is now generally accepted in Judaism.

The Anno Mundi timeline is a theological one. You can’t count backwards from Year One because Time itself didn’t begin until that year. Today we’re in the year am 5780. Anno Mundi and the Hebrew calendar are used in synagogues and Jewish communities around the world.

Maimonides was one of those great thinkers whose influence extended far beyond his own time and place. You can’t believe the amount of stuff he wrote. I’ve given you a mere glimpse of him, but you can read more about Maimonides here.

https://johnmanders.wordpress.com/2019/06/10/the-torah-and-linear-time/

https://en.wikipedia.org/wiki/Hebrew_calendar

https://www.chabad.org/library/article_cdo/aid/75991/jewish/Maimonides-His-Life-and-Works.htm

UPDATE: The current year has been changed to am 5780. Thanks, Jeffrey!

Postcards!

postcard.shot

I got postcards! They have my weird hand-lettering and a lovely astrolabe on the front. The back tells how to find The Western Civ User’s Guide on the internet. I’ll be sending these out to promote my blog and this history I’m writing. The plan is to eventually turn it into a printed book.

If you’d like me to send you a postcard, shoot me an email at john@johnmanders.com.

I do appreciate you guys who read my posts. Thanks for spreading the word.

By the way, these were printed at Best Printing in Oil City, Pennsylvania. Nice job, Licia!

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Title type for my groundbreaking soon-to-be bestseller

Fooling around with lettering. It needs a little tweaking. Some strokes ought to be heavier, maybe. I’m trying to hold onto the energy of my sketch. I’m not sure if I like this yet. Let it sit for a while.