The History of the Compass and Other Magnetic Innovations

The History of the Compass and Other Magnetic Innovations A compass is an instrument containing a freely suspended magnetic element that displays the direction of the horizontal component of Earths magnetic field at the point of observation. Its been used to help people navigate for many centuries. Located in the same part of the public imagination as sextants and telescopes, its actually been in use for a lot longer than the sea voyages that discovered North America. The use of magnetism in inventions doesnt stop there, though; its found in everything from telecommunications equipment and motors to the food chain. Discovery Large deposits of magnetic oxides were found in the district of Magnesia in Asia Minor thousands of years ago; their location led to the mineral receiving the  name of magnetite (Fe3O4), which was nicknamed lodestone. In 1600,  William Gilbert published De Magnete, a paper on magnetism that details the use and properties of magnetite. 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. 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, the Chinese used lodestones (which align themselves in a north-south direction) to construct fortune-telling boards. Eventually, someone noticed that the lodestones were better at pointing out real directions, which led to the creation of the first compasses. The earliest compasses were designed on a square slab that had markings for the cardinal points and the constellations. The pointing needle was a spoon-shaped lodestone 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 eighth century A.D.- again in China- and between 850 and 1050. Compasses as Navigational Aids In the 11th century, compasses use as navigational devices on ships seemed to have become common. The magnetized-needle compasses used in navigation could be wet (in water), dry (on a pointed shaft), or suspended (on silk thread) and were used by voyagers, such as those traders who traveled to the Middle East, and were used by early navigators to locate the magnetic North Pole or pole star. Electromagnetism 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) 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. This device laid the foundation for large-scale  electronic communications, as it led to the invention of the telegraph. It also resulted in the invention of the electric motor.   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. If cows happen to consume scrap pieces of metal, such as nails, when theyre feeding, the foreign objects can cause internal damage to their digestive tract. Cow magnets keep the metal pieces confined to the cows first stomach, rather than traveling to the later stomachs or intestines, where the fragments can cause the most damage.