Tag Archives: magnetic field

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

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How you can harness the awesome and terrible forces of the Earth’s core

We learned last post that the Earth’s core is surrounded by molten metal, which exerts a magnetic field around the planet. Some metals can be magnetized. They can be made into a magnet, so they exert a force on other metals without touching them. Iron and steel can be magnetized.

The thing about Earth’s giant magnetic field is that magnetized metals—if they can—try to line up with it. If you were to take a small piece of iron or steel (like a needle) and rub it a few times with a magnet, it will try to align itself with Earth’s North and South. You could make it easier for the needle if you float it on a piece of styrofoam or cork in a bowl of water. After the needle settles down it will point North-South. Congratulations! You built a compass.

Here’s what you’ll need: a bowl, water, a needle, a piece of cork or styrofoam, and a magnet. I got my magnet off of the refrigerator door. If you cut a slice off the cork, get someone to do it with a craft knife. Use a cutting board! Don’t cut it on your mom’s good dining room table. I don’t want angry messages in the comments section.

Rub the needle with the magnet a bunch of times.

Stick the needle halfway through the cork. It may be a good idea to put the butt-end of the needle on a cutting board and press the cork down onto it.

Fill the bowl with water and float the needle and cork in the water. After a little while the needle will point north-south.

https://www.wikihow.com/Make-a-Compass

https://www.siyavula.com/read/science/grade-10/classification-of-matter/02-classification-of-matter-08

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