A compass is an instrument containing a freely suspended magnetic element which displays the direction of the horizontal component of the Earth's magnetic field at the point of observation. It's been used to help people navigate for many centuries. But who invented it?
Magnetic Compass
The magnetic compass is actually an old Chinese invention, probably first made in China during the Qin dynasty (221-206 B.C.).
Back then, Chinese fortune tellers used lodestones (a mineral composed of an iron oxide which aligns itself in a north-south direction) to construct their fortune telling boards. Eventually, someone noticed that the lodestones were better at pointing out real directions, which lead to the creation of the first compasses.
The earliest compasses were designed on a square slab, which had markings for the cardinal points and the constellations. The pointing needle was a lodestone spoon-shaped device with a handle that would always point south. Later on, magnetized needles were used as direction pointers instead of the spoon-shaped lodestones. These appeared in the 8th century AD -- again in China -- and between 850 and 1050. They seemed to have become common as navigational devices used on ships.
Compass as a Navigational Aid
The first person recorded to have used the compass as a navigational aid was Zheng He (1371-1435) from the Yunnan province in China.
He made seven ocean voyages between 1405 and 1433.
Lodestones, Magnets, Electromagnetism
Ferrites or magnetic oxides are stones that attract iron and other metals. These are natural magnets and are not inventions. However, the machines that we make with magnets are inventions. Ferrites were first discovered thousands of year ago.
Large deposits were found in the district of Magnesia in Asia Minor, which is how mineral got the name of magnetite (Fe3O4).
Magnetite was nicknamed lodestone and used by early navigators to locate the magnetic North Pole. In 1600, William Gilbert published De Magnete, a paper on magnetism that details the use and properties of Magnetite. In 1819, Hans Christian Oersted reported that when an electric current in a wire was applied to a magnetic compass needle the magnet was affected. This is called electromagnetism.
In 1825, British inventor William Sturgeon (1783-1850) exhibited a device that laid the foundation for large-scale electronic communications. Sturgeon displayed the power of the electromagnet by lifting nine pounds with a seven-ounce piece of iron wrapped with wires through which the current of a single cell battery was sent.
Cow Magnets
U.S. patent #3,005,458 is the first patent issued for a cow magnet. It was issued to Louis Paul Longo, the inventor of the Magnetrol Magnet, for the prevention of hardware disease in cows.
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