How do compasses work?
From Antiquus we want to unveil this great invention… its functioning, its discovery, and its daily life…
Compasses are one of man’s greatest inventions and without them we would not have been able to discover the world or make the first transoceanic voyages.
It is an instrument that serves for orientation and that has its foundation in the property of the magnetized needles. In the magnetic compass
magnetic compass, the bearing is determined by one or more magnetized needles pointing to the magnetic north pole under the influence of the earth’s magnetic field.
Before the creation of the compass, the direction in the open sea was determined by the position of the celestial bodies, but often the sky was too cloudy and therefore it was necessary to find another way of navigating much safer, without depending on weather conditions.
The discovery of an Olmec magnetite artifact that functioned similarly to a compass has generated theories that “the Olmecs may have discovered and used a magnetite compass as early as before 1000 BC”.
Joseph Needham attributes the invention of the compass to China. The first undisputed reference to a magnetized needle in Chinese writings appears in a book written during the Song dynasty.The Chinese used a small piece of reed containing a magnetic needle that was floated on water, and thus indicated magnetic north. But at certain times it was not useful, as it needed to be in calm water, so it was perfected by the Italians.
In Europe, the compass is officially known since the Renaissance, initially it was believed to work by witchcraft hence its most common name which is a diminutive of witch; from the late Middle Ages and until about the mid-nineteenth century it was believed that the magnetized compass pointed to the magnetic needle. that the magnetized needle pointed towards the North Pole and it was believed that this happened because it was supposed that there was in the North Pole a gigantic iron or Magnetite mountain in the middle of an (imaginary) island which was called Rupes Nigra.
The first practical navigational compass was invented by an armorer from Positano, Italy, named Flavio Gioja, between the 14th and 15th centuries. He was the one who perfected it by suspending the needle on a spike similar to the one it still has today. And he enclosed it in a small box with a glass lid. Later appeared the “compass rose”, a disc with marks of divisions of degrees and subdivisions, which indicated 32 celestial directions, and which was the marine compass used until the end of the 19th century.
The planet Earth has an iron core that, because of its gravitational pressure, is partly liquid and solid. Scientists believe that the movement of the liquid part is what produces the Earth’s magnetic field.
This field has two main axes: south and north and are used as the geographical bases.
Compasses are made of light magnets, usually in the form of magnetized needles on a freely rotating axis, which allow them to react in the best way to magnetic fields.
The South Pole of the needle is attracted to the North Pole of the Earth and this is how explorers can know which is north and guide themselves based on the four cardinal points.
That’s why compasses only point north!
Compasses were extremely popular during the Middle Ages as this was the period when Europeans began to explore the Earth.
During sea voyages in wooden ships, they were placed inside boxes that were placed next to the rudders.
Centuries later, when iron ships were built, scientists had to study the functioning of compasses in greater depth, as this material altered their movement.
Faced with this problem, they began to use Flinder’s rod , which was a piece of iron that was placed in the box where the needles are. This rod was only used for compasses installed in iron ships to correct the orientation.
These objects continued to evolve and later the gyrocompass was created for airplanes. This does not alter despite the objects around it and maintains a stable position with respect to the stars so that the needle always points to the geographic north of the Earth.
Despite technological advances and the use of radar and GPS, they are still of great use to travelers and explorers and one of man’s most brilliant inventions.
In Antiquus we have a great variety of compasses, we leave you the link so that you can take a look at them.