When was the compass invented? The compass was invented in China in the 4th century BC. However, it wasn’t used for navigation until over a thousand years later, also in China.
A compass works because our planet has a magnetic field. The magnetic field is generated by the spinning ball of iron at the center of our planet. The core is a solid ball of iron inside a liquid ball of iron. When the liquid iron spins around the solid iron, it becomes a dynamo, a basic electric engine, and it produces an electric current. When you have an electric current, you get a magnetic field. This magnetic field is vital to life on Earth because it shields us from particles that come off the sun in the solar wind. These particles bouncing off our magnetic field are what create the beautiful aurora borealis. The magnetic field is also vital for many animals. We cannot see it without the aid of a compass, but there are a lot of animals that can sense, or even see the magnetic field and they use it to navigate.
The magnetic field comes from the magnetic south pole and heads to the magnetic north pole. These are not quite the same as the true north and south poles. Magnetic North is about 1,200 km away from true north, but it is not constant and moves year to year. Right now, it is just north of Canada. Magnetic north is heading towards Siberia and it moves about 50 km a year. Airplanes, ships, and anything that relies on a compass direction needs to be updated every year so it can calculate the difference between magnetic north and true north.
The first compass built in China was made of lodestone. Lodestone is a mineral called magnetite that has been naturally magnetized. Magnetite is a type of iron ore, but it is not naturally magnetized. Only the pieces that have been magnetized are called lodestone and nobody knows how they get magnetized. One theory is that lodestone is formed when magnetite is hit by a lightning bolt. Because lodestone is a natural magnet, it will align itself with the Earth’s magnetic field, pointing north and south. The Chinese cut the lodestone into a ladle shape and placed it on a bronze plate. The ladle was balanced so that it could rotate freely and the long handle always pointed to the south. Because of this, they were known as “south pointing spoons” or “south pointers”. The bronze plate had a circle cut into it to represent the Earth and markings for north, south, east, and west. The compass was not used for navigation, but for Feng Shui and for religious purposes.
Over the next several centuries, the Chinese compass underwent a few changes. Instead of using lodestone, Chinese people worked out how to magnetize an iron needle. They found that when the magnetized iron needle was attached to a piece of cork and allowed to float freely in a bowl of water, it would rotate until it was aligned with the north. That meant it was now possible to take a compass with you because as long as you had water, you could set it up. By the 11th century AD, it was being used for navigation across land in China and by 1088, it was being used on ships. Because of its shape, it became known as the “south pointing fish”. The bowl was set on a board with North, South, East, and West painted on it, but these were soon increased to include 48 different positions. These compasses were probably used as a backup to the normal methods of navigating by the stars.
The next step was dry compasses, which would work without a bowl of water. The magnetized needle was suspended on a small pivot point, which allowed it to rotate freely. Then, in about 1300, the compass style we use today was invented. The needle is attached to a round compass card with the cardinal directions and degrees on it. As the compass is rotated in the hand, the needle always point at north and the needle and the card with the directions move inside the box. That makes it much easier to work out where you are heading in relation to north. That compass was invented in Italy, but it couldn’t have been made without all of the inventions that came out of China. It is known that the knowledge first went to India and the Arabic world because in both of those places, compasses were called “fishes” or “fish machines”, which presumably came from the Chinese name. Compasses were carried there by traders and then onwards into Europe, as was the way with many things. Without compasses, it is doubtful that Europe would have been able to go on its Voyages of Discovery. And this is what I learned today.
Try these
Sources
https://www.earth.com/news/magnetic-north-pole-is-moving-faster-than-ever-as-it-races-toward-russia
https://geomag.nrcan.gc.ca/mag_fld/compass-en.php
https://en.wikipedia.org/wiki/History_of_the_compass
https://en.wikipedia.org/wiki/Lodestone
https://education.nationalgeographic.org/resource/compass
Photo by Valentin Antonucci: https://www.pexels.com/photo/person-holding-compass-691637/