Magnets were discovered in China and Greece. In China it was used in fortune telling and as a guide to building. By 1200 AD they were used in ships as compasses. Ever since, sailors and navigators have used compasses and the earth’s magnetic field to guide them in their journeys, whether on land or at sea.

Legends have it that Magnes, the Greek shepherd discovered the magnetic properties of lodestone when his iron staff was stuck to the lodestone and he was unable to dislodge it. Another legend has it that magnets were discovered in Magnesia, a place in Turkey.

Traditional Chinese Medicine which dates back to 2600 BC used magnetic stones on certain areas of the body to correct imbalance. The Vedas, dating back to 1500 BC, mentioned the use of lodestone in healing. The dead were buried with the head facing north to create harmony between the body and the earth.

Thales, a Greek philosopher, described the magnetic effects of lodestone in the seventh century BC. When St. Augustine arrived in Britain in the sixth century, he noted that lodestone was being used.

Compasses were developed where the lodestone was suspended by a piece of string, then later by a piece of wood in water. This was subsequently replaced by the dry suspension magnets.

In 1269, Pierre de Maricourt mapped the magnetic field around the lodestone. William Gilbert in the sixteenth century recognised the two poles, north and south. He also described the healing properties of magnets. Gilbert realised that iron rods left in a north south direction in alignment with the earth’s magnetic field, became weakly magnetised after 20 years. He suggested that lightning could magnetise iron. He also found that if a blacksmith heated an iron rod, and cooled with the rod lying in a north south direction, it becomes magnetised if the blacksmith hammered it while it is cooling.

The horseshoe magnet was developed by bending a straight iron magnet into the shape of a horseshoe. With the north and south poles so near to each other, the power of the magnet was doubled.

Iron magnets were heavy. Lightweight powerful magnets were soon developed. In the eighteenth century, carbon steel magnets were developed. It retained its magnetism better than beaten iron.

The first alloy containing magnet was developed in the early twentieth century and contained cobalt, tungsten, molybdenum or chromium. The next development was in the 1930s when iron was alloyed with aluminium, nickel and cobalt. These magnets were called Alnico magnets. These magnets were still metal based and therefore heavy to use.

In 1980s, magnets incorporating cobalt and samarium were used. They were the rare earth magnets. They were lighter and were used in industry. They were, however, expensive. In 1983, magnets using iron, boron and neodymium were produced. They were called Neodymium Magnets. They are very difficult to demagnetise and will remain magnetised for several decades. The process by which neodymium magnets were developed is called sintering. High temperature and pressure are applied to the powdered metals. This, however, means the magnets are brittle but this can be overcome by using a strong metal casing. A Neodymium magnet of say 8000 gauss weighs 20 gm while the comparable strength Alnico magnet weighs 90kg.

In the nineteenth century, Hans Christian Oersted, professor of physics at Copenhagen discovered that an electric current developed a magnetic field. In 1830s Michael Faraday and Joseph Henry independently discovered that a magnetic field produced electricity.

James Clerk Maxwell, a British physicist developed the Cork Screw Rule for calculating the direction of electrical flow when an object is moved in a magnetic field. In 1820 Andre Marie produced a mathematical relationship between electricity and the strength of the magnetic field.

Franz Anton Mesmer was the eponymous Viennese psychiatrist who developed the theory of animal magnetism. In his magnetic seances, Mesmer placed individuals in a magnetic tub, and made them relax. He then touched them, sending them into a trance. When they woke up, they were cured.

Pierre Curie discovered that magnets lose their magnetism above a specific temperature. This is now known as the Curie point. Edward Purcell & Flix Bloch developed a way to measure the magnetic field of nuclei. This led to the development of the MRI (Magnetic Resonance Imaging) scan.

In the 1960-1970 superconductors were developed. Magnets were cooled to absolute zero. These magnets can generate fields up to 200,000 gauss. It is used today in nuclear research.
Dr. Phil Hariram.

Arthritis Guide.