-
1 Maxwell, James Clerk
[br]b. 13 June 1831 Edinburgh, Scotlandd. 5 November 1879 Cambridge, England[br]Scottish physicist who formulated the unified theory of electromagnetism, the kinetic theory of gases and a theory of colour.[br]Maxwell attended school at the Edinburgh Academy and at the age of 16 went on to study at Edinburgh University. In 1850 he entered Trinity College, Cambridge, where he graduated four years later as Second Wrangler with the award of the Smith's Prize. Two years later he was appointed Professor at Marischal College, Aberdeen, where he married the Principal's daughter. In 1860 he moved to King's College London, but on the death of his father five years later, Maxwell returned to the family home in Scotland, where he continued his researches as far as the life of a gentleman farmer allowed. This rural existence was interrupted in 1874 when he was persuaded to accept the chair of Cavendish Professor of Experimental Physics at Cambridge. Unfortunately, in 1879 he contracted the cancer that brought his brilliant career to an untimely end. While at Cambridge, Maxwell founded the Cavendish Laboratory for research in physics. A succession of distinguished physicists headed the laboratory, making it one of the world's great centres for notable discoveries in physics.During the mid-1850s, Maxwell worked towards a theory to explain electrical and magnetic phenomena in mathematical terms, culminating in 1864 with the formulation of the fundamental equations of electromagnetism (Maxwell's equations). These equations also described the propagation of light, for he had shown that light consists of transverse electromagnetic waves in a hypothetical medium, the "ether". This great synthesis of theories uniting a wide range of phenomena is worthy to set beside those of Sir Isaac Newton and Einstein. Like all such syntheses, it led on to further discoveries. Maxwell himself had suggested that light represented only a small part of the spectrum of electromagnetic waves, and in 1888 Hertz confirmed the discovery of another small part of the spectrum, radio waves, with momentous implications for the development of telecommunication technology. Maxwell contributed to the kinetic theory of gases, which by then were viewed as consisting of a mass of randomly moving molecules colliding with each other and with the walls of the containing vessel. From 1869 Maxwell applied statistical methods to describe the molecular motion in mathematical terms. This led to a greater understanding of the behaviour of gases, with important consequences for the chemical industry.Of more direct technological application was Maxwell's work on colour vision, begun in 1849, showing that all colours could be derived from the three primary colours, red, yellow and blue. This enabled him in 1861 to produce the first colour photograph, of a tartan. Maxwell's discoveries about colour vision were quickly taken up and led to the development of colour printing and photography.[br]BibliographyMost of his technical papers are reprinted in The Scientific Papers of J.Clerk Maxwell, 1890, ed. W.D.Niven, Cambridge, 2 vols; reprinted 1952, New York.Maxwell published several books, including Theory of Heat, 1870, London (1894, 11th edn, with notes by Lord Rayleigh) and Theory of Electricity and Magnetism, 1873, Oxford (1891, ed. J.J.Thomson, 3rd edn).Further ReadingL.Campbell and W.Garnett, 1882, The Life of James Clerk Maxwell, London (the standard biography).J.J.Thomson (ed.), 1931, James Clerk Maxwell 1831–1931, Cambridge. J.G.Crowther, 1932, British Scientists of the Nineteenth Century, London.LRD -
2 James Clerk Maxwell
-
3 Maxwell
n. James Clerk Maxwell (1831-79), Schots natuurkundige, grondlegger van Maxwell's vergelijkingen voor lichtmagnetisme en elektriciteit; familienaam -
4 Chemical technology
-
5 Electricity
-
6 Sutton, Thomas
SUBJECT AREA: Photography, film and optics[br]b. 1819 Englandd. 1875 Jersey, Channel Islands[br]English photographer and writer on photography.[br]In 1841, while studying at Cambridge, Sutton became interested in photography and tried out the current processes, daguerreotype, calotype and cyanotype among them. He subsequently settled in Jersey, where he continued his photographic studies. In 1855 he opened a photographic printing works in Jersey, in partnership with L.-D. Blanquart- Evrard, exploiting the latter's process for producing developed positive prints. He started and edited one of the first photographic periodicals, Photographic Notes, in 1856; until its cessation in 1867, his journal presented a fresher view of the world of photography than that given by its London-based rivals. He also drew up the first dictionary of photography in 1858.In 1859 Sutton designed and patented a wideangle lens in which the space between two meniscus lenses, forming parts of a sphere and sealed in a metal rim, was filled with water; the lens so formed could cover an angle of up to 120 degrees at an aperture of f12. Sutton's design was inspired by observing the images produced by the water-filled sphere of a "snowstorm" souvenir brought home from Paris! Sutton commissioned the London camera-maker Frederick Cox to make the Panoramic camera, demonstrating the first model in January 1860; it took panoramic pictures on curved glass plates 152×381 mm in size. Cox later advertised other models in a total of four sizes. In January 1861 Sutton handed over manufacture to Andrew Ross's son Thomas Ross, who produced much-improved lenses and also cameras in three sizes. Sutton then developed the first single-lens reflex camera design, patenting it on 20 August 1961: a pivoted mirror, placed at 45 degrees inside the camera, reflected the image from the lens onto a ground glass-screen set in the top of the camera for framing and focusing. When ready, the mirror was swung up out of the way to allow light to reach the plate at the back of the camera. The design was manufactured for a few years by Thomas Ross and J.H. Dallmeyer.In 1861 James Clerk Maxwell asked Sutton to prepare a series of photographs for use in his lecture "On the theory of three primary colours", to be presented at the Royal Institution in London on 17 May 1861. Maxwell required three photographs to be taken through red, green and blue filters, which were to be printed as lantern slides and projected in superimposition through three projectors. If his theory was correct, a colour reproduction of the original subject would be produced. Sutton used liquid filters: ammoniacal copper sulphate for blue, copper chloride for the green and iron sulphocyanide for the red. A fourth exposure was made through lemon-yellow glass, but was not used in the final demonstration. A tartan ribbon in a bow was used as the subject; the wet-collodion process in current use required six seconds for the blue exposure, about twice what would have been needed without the filter. After twelve minutes no trace of image was produced through the green filter, which had to be diluted to a pale green: a twelve-minute exposure then produced a serviceable negative. Eight minutes was enough to record an image through the red filter, although since the process was sensitive only to blue light, nothing at all should have been recorded. In 1961, R.M.Evans of the Kodak Research Laboratory showed that the red liquid transmitted ultraviolet radiation, and by an extraordinary coincidence many natural red dye-stuffs reflect ultraviolet. Thus the red separation was made on the basis of non-visible radiation rather than red, but the net result was correct and the projected images did give an identifiable reproduction of the original. Sutton's photographs enabled Maxwell to establish the validity of his theory and to provide the basis upon which all subsequent methods of colour photography have been founded.JW / BC -
7 Hertz, Heinrich Rudolph
[br]b. 22 February 1857 Hamburg, Germanyd. 1 January 1894 Bonn, Germany[br]German physicist who was reputedly the first person to transmit and receive radio waves.[br]At the age of 17 Hertz entered the Gelehrtenschule of the Johaneums in Hamburg, but he left the following year to obtain practical experience for a year with a firm of engineers in Frankfurt am Main. He then spent six months at the Dresden Technical High School, followed by year of military service in Berlin. At this point he decided to switch from engineering to physics, and after a year in Munich he studied physics under Helmholtz at the University of Berlin, gaining his PhD with high honours in 1880. From 1883 to 1885 he was a privat-dozent at Kiel, during which time he studied the electromagnetic theory of James Clerk Maxwell. In 1885 he succeeded to the Chair in Physics at Karlsruhe Technical High School. There, in 1887, he constructed a rudimentary transmitter consisting of two 30 cm (12 in.) rods with metal balls separated by a 7.5 mm (0.3 in.) gap at the inner ends and metallic plates at the outer ends, the whole assembly being mounted at the focus of a large parabolic metal mirror and the two rods being connected to an induction coil. At the other side of his laboratory he placed a 70 cm (27½ in.) diameter wire loop with a similar air gap at the focus of a second metal mirror. When the induction coil was made to create a spark across the transmitter air gap, he found that a spark also occurred at the "receiver". By a series of experiments he was not only able to show that the invisible waves travelled in straight lines and were reflected by the parabolic mirrors, but also that the vibrations could be refracted like visible light and had a similar wavelength. By this first transmission and reception of radio waves he thus confirmed the theoretical predictions made by Maxwell some twenty years earlier. It was probably in his experiments with this apparatus in 1887 that Hertz also observed that the voltage at which a spark was able to jump a gap was significantly reduced by the presence of ultraviolet light. This so-called photoelectric effect was subsequently placed on a theoretical basis by Albert Einstein in 1905. In 1889 he became Professor of Physics at the University of Bonn, where he continued to investigate the nature of electric discharges in gases at low pressure until his death after a long and painful illness. In recognition of his measurement of radio and other waves, the international unit of frequency of an oscillatory wave, the cycle per second, is now universally known as the Hertz.[br]Principal Honours and DistinctionsRoyal Society Rumford Medal 1890.BibliographyMuch of Hertz's work, including his 1890 paper "On the fundamental equations of electrodynamics for bodies at rest", is recorded in three collections of his papers which are available in English translations by D.E.Jones et al., namely Electric Waves (1893), Miscellaneous Papers (1896) and Principles of Mechanics (1899).Further ReadingJ.G.O'Hara and W.Pricha, 1987, Hertz and the Maxwellians, London: Peter Peregrinus. J.Hertz, 1977, Heinrich Hertz, Memoirs, Letters and Diaries, San Francisco: San Francisco Press.R.Appleyard, 1930, Pioneers of Electrical Communication.See also: Heaviside, OliverKFBiographical history of technology > Hertz, Heinrich Rudolph
См. также в других словарях:
Maxwell, James Clerk — born June 13, 1831, Edinburgh, Scot. died Nov. 5, 1879, Cambridge, Cambridgeshire, Eng. Scottish physicist. He published his first scientific paper at age 14, entered the University of Edinburgh at 16, and graduated from Cambridge University. He… … Universalium
Maxwell,James Clerk — Max·well (măksʹwĕl , wəl), James Clerk. 1831 1879. British physicist who made fundamental contributions to electromagnetic theory and the kinetic theory of gases. * * * … Universalium
Maxwell , James Clerk — (1831–1879) British physicist Maxwell was born in Edinburgh and studied at the university there (1847–50) and at Cambridge (1850–54), becoming a fellow in 1855. He was professor of natural philosophy at Marishal College, Aberdeen, from 1856 until … Scientists
MAXWELL, JAMES CLERK — eminent physicist, born in Edinburgh, son of John Clerk Maxwell of Middlebie; attained the rank of senior wrangler at Cambridge; became professor in Aberdeen in 1856, in London in 1860, and of Experimental Physics in Cambridge in 1871; in this … The Nuttall Encyclopaedia
Maxwell, James Clerk — ► (1831 79) Físico escocés. Es autor de importantes trabajos sobre la teoría cinética de los gases y el electromagnetismo. Demostró que los fenómenos luminosos y los electromagnéticos se propagan a la velocidad de la luz. * * * (13 jun. 1831,… … Enciclopedia Universal
James Clerk Maxwell — (1831–1879) Born 13 June 1831 … Wikipedia
James Clerk Maxwell — (* 13. Juni 1831 in Edinburgh; † 5. November 1879 … Deutsch Wikipedia
James Clerk Maxwell — Pour les articles homonymes, voir Maxwell. James Clerk Maxwell James Clerk Maxwell Naissance 13 … Wikipédia en Français
James Clerk Maxwell — Para otros usos de este término, véase Maxwell (desambiguación). James Clerk Maxwell James Clerk Maxwell Nacimiento … Wikipedia Español
James Clerk Maxwell — noun Scottish physicist whose equations unified electricity and magnetism and who recognized the electromagnetic nature of light (1831 1879) • Syn: ↑Maxwell, ↑J. C. Maxwell • Instance Hypernyms: ↑physicist * * * James Clerk Maxwell [James Clerk… … Useful english dictionary
James Clerk Maxwell — (Edimburgo, 13 de junio de 1831 Glenlair, Reino Unido, 5 de noviembre de 1879). Físico británico. Nació en el seno de una familia escocesa de la clase media, hijo único de un abogado de Edimburgo. Tras la temprana muerte de su madre a causa de un … Enciclopedia Universal