Tag Archives: compass

It’s been a long trip so far

I want to take a moment to thank everyone who’s been hanging with me throughout this little history. I feel like I’ve been telling a year-and-a-half-long joke and I’m just about to get to the punchline.

Since January last year, we discovered how people in the past measured space and measured time. We followed along as travelers ventured further and further from home—traders and explorers became bold enough to make long voyages across the oceans without knowing exactly where they were. To navigate, you need to measure both time and space. Most of the inventions that measure time and space didn’t appear until around the 1500s.

Here’s what you need if you plan to cross an ocean and would like to know where you are going:
1. an accurate map, to know what you’re looking for
2. a compass, to orient the map
3. an astrolabe, to find latitude (how far north or south you are)
4. universal time, to find longitude (how far east or west you are)—Galileo proposed that if you can see the positions of Jupiter’s moons, and you know what time it is locally, you can figure out your longitude. Jupiter’s moons would be a universal clock.
5. an accurate clock, to know local time

The Exploration Age sailors set sail without an accurate map or clock, because those things didn’t exist yet (a pendulum clock doesn’t work on a rocking ship).
Astrolabes or Jupiter’s moons are only useful when the sky is clear. So, even in the 1500s sailors didn’t have all the tools they needed for navigating.

Back to the beginning of The Western Civ User’s Guide to Time & Space

Maps, we need maps!

As we’ve seen, Venice was hopping with trade on the Mediterranean Sea and beyond. With their compasses and astrolabes and lightly-built galleons, Venetian traders traveled all over the known world. Likewise, traders from all over the world stopped in Venice. Compasses work best with a map, so Venice’s map-making (cartography) business was booming.

In ad 1450, in a monastery in Venice, there lived a monk named Fra Mauro (Brother Mauro). Fra Mauro was an extraordinary cartographer and his map is the one you see pictured here. It’s about 6 feet across.

It’s not easy to recognize all the continents right away, because he drew it with North at the bottom. We’re used to seeing North at the top of maps. I’m not sure when it became standard practice to put North at the top. Over at the extreme right, you can see a little compass-rose with North pointing down. As you work your way left from there, you’ll see Spain and Portugal, the Straits of Gibraltar where Europe almost touches Africa, and the Mediterranean Sea where the boot of Italy is kicking up rather than down. The shapes of Africa and Asia are difficult to recognize, too. It would be a while before cartographers could accurately survey land masses. Africa is in the upper-right. Asia takes up almost all the the left half of the map.

The New World—the Americas and Australia—hadn’t been discovered yet.

Here’s an article about Fra Mauro, with some close-ups of his map.

How to not get lost

Here’s a simple compass

The compass was developed into a compact design. Instead of balancing an iron spoon or floating a piece of magnetized iron in a bowl of water, compass designers suspended a magnetized iron arrow on a thin metal pin over a round card with directions displayed on it. The arrow and card were put in a round brass housing to protect them. Brass can’t be magnetized, so the housing didn’t interfere with the arrow’s attraction to the north pole.

This compass is designed to be used on a boat. Instead of a needle, the entire card spins on an axis to point north. The compass is mounted on gimbals—the outside ring is mounted to the wooden box on the right and left sides. The compass is mounted to the ring top and bottom. This allows it to stay level while the boat bounces around on the waves.

Compass-makers put North, South, East and West (the cardinal directions) on their compass cards, then NorthNorthEast, NorthEast, EastNorthEast, EastSouthEast, SouthEast, SouthSouthEast, SouthSouthWest, SouthWest, WestSouthWest, WestNorthWest, NorthWest, NorthNorthWest and eventually all 32 points of direction.

Compass rose

Mapmakers began to indicate North on their maps so that you could line your map up with the compass’ arrow. This became the lovely compass rose you see on those gorgeous old maps.

This is the kind of compass my pals and I used in the Boy Scouts. The ring is aluminum, I think, and has 360 degrees marked along the bottom edge. The rectangular base is clear plastic so you can see a map through it. It also has a ruler along the side. They make ’em with a magnifying glass in the plastic now.

You’re never lost if you have a map and a compass. Sea-farers were the first to use this technology but it works on land, too! There’s a scene in the movie The Big Country (it’s about a sea captain who decides to settle in the old American West) where sea-captain Gregory Peck goes exploring the countryside for a few days and all the ranchers are worried sick that he got lost in the desert. Everyone is relieved when he rides back to the ranch without a scratch. “How did you not get lost?” they want to know. Greg can’t understand what the fuss is about. “I had a compass,” he says. An epic Western—great soundtrack, too.

https://www.nationalgeographic.org/encyclopedia/compass/

http://www.historyofcompass.com/compass-history/history-of-the-magnetic-compass/

https://www.smith.edu/hsc/museum/ancient_inventions/compass2.html

https://spectrum.ieee.org/the-institute/ieee-history/history-lesson-the-magnetic-compass

Back to the beginning of The Western Civ User’s Guide to Time & Space

The Chinese invent the compass

A thin piece of magnetized iron in the shape of a fish (or a shallow boat) floats in water and points north.

The magnetic compass was invented in China sometime between the 2nd century bc and ad 1st century. They used it to make sure streets and houses aligned with the Earth in a harmonious way—what is called feng shui. The Chinese later figured out they could use a compass for finding their way on the ocean (ad 1040-44).

This carefully-balanced magnetized iron spoon points north with its handle.