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William Gilbert (; 24 May 1544 – 30 November 1603), also known as Gilberd, was an English physician, physicist and natural philosopher. He passionately rejected both the prevailing Aristotelian philosophy and the Scholastic method of university teaching. He is remembered today largely for his book ''De Magnete'' (1600), and is credited as one of the originators of the term "electricity". He is regarded by some as the father of electrical engineering or electricity and magnetism.〔Merriam-Webster Collegiate Dictionary, 2000, CD-ROM, version 2.5.〕 While today he is generally referred to as William Gilbert, he also went under the name of William Gilberd. The latter was used in both his and his father's epitaphs, in the records of the town of Colchester, in the Biographical Memoir that appears in ''De Magnete'', and in the name of The Gilberd School in Colchester. A unit of magnetomotive force, also known as magnetic potential, was named the G''ilbert'' in his honour. == Life and work == Gilbert was born in Colchester to Jerome Gilberd, a borough recorder. He was educated at St John's College, Cambridge. After gaining his MD from Cambridge in 1569, and a short spell as bursar of St John's College, he left to practice medicine in London and travelled on the continent. In 1573, he was elected a Fellow of the Royal College of Physicians. In 1600 he was elected President of the College.〔Gilbert (1893)〕 From 1601 until her death in 1603, he was Elizabeth I's own physician, and James VI and I renewed his appointment. His primary scientific work—much inspired by earlier works of Robert Norman〔Roller, Duane H D (1959) ''The De Magnete of William Gilbert'', Amsterdam.〕—was ''De Magnete, Magneticisque Corporibus, et de Magno Magnete Tellure'' (''On the Magnet and Magnetic Bodies, and on the Great Magnet the Earth'') published in 1600. In this work, he describes many of his experiments with his model Earth called the terrella. From these experiments, he concluded that the Earth was itself magnetic and that this was the reason compasses point north (previously, some believed that it was the pole star (Polaris) or a large magnetic island on the north pole that attracted the compass). He was the first to argue, correctly, that the centre of the Earth was iron, and he considered an important and related property of magnets was that they can be cut, each forming a new magnet with north and south poles. In Book 6, Chapter 3, he argues in support of diurnal rotation, though he does not talk about heliocentrism, stating that it is an absurdity to think that the immense celestial spheres (doubting even that they exist) rotate daily, as opposed to the diurnal rotation of the much smaller Earth. He also posits that the "fixed" stars are at remote variable distances rather than fixed to an imaginary sphere. He states that situated "in thinnest aether, or in the most subtle fifth essence, or in vacuity – how shall the stars keep their places in the mighty swirl of these enormous spheres composed of a substance of which no one knows aught?" The English word "electricity" was first used in 1646 by Sir Thomas Browne, derived from Gilbert's 1600 New Latin ''electricus'', meaning "like amber". The term had been in use since the 13th century, but Gilbert was the first to use it to mean "like amber in its attractive properties". He recognized that friction with these objects removed a so-called "effluvium", which would cause the attraction effect in returning to the object, though he did not realize that this substance (electric charge) was universal to all materials. In his book, he also studied static electricity using amber; amber is called ''elektron'' in Greek, so Gilbert decided to call its effect the ''electric force''. He invented the first electrical measuring instrument, the electroscope, in the form of a pivoted needle he called the ''versorium''.〔 a translation of William Gilbert (1600) ''Die Magnete''〕 Like others of his day, he believed that crystal (quartz) was an especially hard form of water, formed from compressed ice: Gilbert argued that electricity and magnetism were not the same thing. For evidence, he (incorrectly) pointed out that, while electrical attraction disappeared with heat, magnetic attraction did not (although it is proven that magnetism does in fact become damaged and weakened with heat). Hans Christian Ørsted and James Clerk Maxwell showed that both effects were aspects of a single force: electromagnetism. Maxwell surmised this in his ''A Treatise on Electricity and Magnetism'' after much analysis. Gilbert's magnetism was the invisible force that many other natural philosophers, such as Kepler, seized upon, incorrectly, as governing the motions that they observed. While not attributing magnetism to attraction among the stars, Gilbert pointed out the motion of the skies was due to earth's rotation, and not the rotation of the spheres, 20 years before Galileo (but 57 years after Copernicus who stated it openly in his work "De revolutionibus orbium coelestium" published in 1543 ) (see external reference below). Gilbert made the first attempt to map the surface markings on the Moon in the 1590s. His chart, made without the use of a telescope, showed outlines of dark and light patches on the moon's face. Contrary to most of his contemporaries, Gilbert believed that the light spots on the Moon were water, and the dark spots land.〔Bochenski, Leslie (April 1996) ("A Short History of Lunar Cartography" ). University of Illinois Astronomical Society〕 Besides Gilbert's ''De Magnete'', there appeared at Amsterdam in 1651 a quarto volume of 316 pages entitled ''De Mundo Nostro Sublunari Philosophia Nova'' (New Philosophy about our Sublunary World), edited—some say by his brother William Gilbert Junior, and others say, by the eminent English scholar and critic John Gruter—from two manuscripts found in the library of Sir William Boswell. According to Dr. John Davy, "this work of Gilbert's, which is so little known, is a very remarkable one both in style and matter; and there is a vigor and energy of expression belonging to it very suitable to its originality. Possessed of a more minute and practical knowledge of natural philosophy than Bacon, his opposition to the philosophy of the schools was more searching and particular, and at the same time probably little less efficient." In the opinion of Prof. John Robison, ''De Mundo'' consists of an attempt to establish a new system of natural philosophy upon the ruins of the Aristotelian doctrine.〔Gilbert (1893) p. xxv〕 Dr. William Whewell says in his ''History of the Inductive Sciences'' (1859):〔Whewell, William (1859) ''History of the Inductive Sciences''. D. Appleton. (Vol. 1 ). p. 394〕
Gilbert died on 30 November 1603 in London. His cause of death is thought to have been the bubonic plague.〔(William Gilbert ). National High Magnetic Field Laboratory〕〔(William Gilbert (1544–1603) ). BBC〕 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「William Gilbert (astronomer)」の詳細全文を読む スポンサード リンク
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