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See also:JULIUS See also:PLUCKER (18or-1868) , See also:German mathematician and physicist, was See also:born at See also:Elberfeld on the 16th of See also:June 18oI . After being educated at See also:Dusseldorf and at the See also:universities of See also:Bonn, See also:Heidelberg and See also:Berlin he went in 1823 to See also:Paris, where he came under the See also:influence of the See also:great school of See also:French geometers, whose founder, Gaspard See also:Monge, was only recently dead . In 1825 he was received as Privatdozent at Bonn, and after three years he was made See also:professor extraordinary The See also:title of his " habilitationsschrift," Generalem analyseos applicationem ad See also:ea quae geometriae altioris et mechanicae basis et fundamenta sunt a serie Tayloria deducit See also:Julius See also:Plucker (Bonn, 1824), indicated the course of his future researches . The mathematical influence of Monge had two sides represented respectively by his two great See also:works, the Geometrie descriptive and the Application de l'analyse d la geometrie . Plucker aimed at furnishing See also:modern See also:geometry with suitable See also:analytical methods so as to give it an See also:independent analytical development . In this effort he was as successful as were his great contemporaries See also:Poncelet and J . See also:Steiner in cultivating geometry in its purely synthetic See also:form . From his lectures and researches at Bonn sprang his first great See also:work, Analytisch-geometriscke Entwickelungen (vol. i., 1828; vol. ii., 1831) . In the first See also:volume of this See also:treatise Plucker introduced for the first See also:time the method of abridged notation which has become one of the characteristic features of modern analytical geometry (see GEOMETRY, ANALYTICAL) . In the first volume of the Entwickelungen he applied the method of abridged notation to the straight See also:line, circle and conic sections, and he subsequently used it with great effect in many of his researches, notably in his theory of cubic curves . In the second volume of the Entwickelungen he clearly established on a See also:firm and independent basis the great principle of duality . Another subject of importance which Plucker took up in the Entwickelungen was the curious See also:paradox noticed by L . See also:Euler and G . See also:Cramer, that, when a certain number of the intersections of two algebraical curves are given, the See also:rest are thereby determined . Gergonne had shown that when a number of the intersections of two curves of the (p+q)th degree See also:lie on a See also:curve of the pth degree the rest lie on a curve of the qth degree . Plucker finally (Gergonne See also:Ann., 1828–1829) showed how many points must be taken on a curve of any degree so that curves of the same degree (See also:infinite in number) may be See also:drawn through them, and proved that all the points, beyond the given ones, in which these curves intersect the given one are fixed by the See also:original choice . Later, simultaneously with C . G . J . See also:Jacobi, he extended these results to curves and surfaces of unequal See also:order . Allied to the See also:matter just mentioned was Plucker's See also:discovery of the six equations connecting the See also:numbers of singularities in algebraical curves (see CURVE) . Plucker communicated his formulae in the first See also:place to Crelle's See also:Journal (1834), vol. xii., and gave a further See also:extension and See also:complete See also:account of his theory in his Theorie der algebraischen Curven (1839) . In 1833 Plucker See also:left Bonn for Berlin, where he occupied a See also:post in the See also:Friedrich Wilhelm's Gymnasium . He was then called in 1834 as See also:ordinary professor of See also:mathematics to See also:Halle . While there he published his See also:System der analytischen Geometrie, auf neue Betrachtungsweisen gegrundet, and insbesondere eine ausfuhrliche Theorie der Curven drifter Ordnung enthaltend (Berlin, 1835) . In this work he introduced the use of linear functions in place of the ordinary co-ordinates; he also made the fullest use of the principles of collineation and See also:reciprocity . His discussion of curves of the third order turned mainly on the nature of their asymptotes, and depended on the fact that the See also:equation to every such curve can be put into the form pgr+p.s=o . He gives a complete enumeration of them, including two See also:hundred and nineteen See also:species . In 1836 Plucker returned to Bonn as ordinary professor of mathematics . Here he published his Theorie der algebraischen Curven, which formed a continuation of the System der analytischen Geometric The work falls into two parts, which treat of the asymptotes and singularities of algebraical curves respectively; and extensive use is made of the method of counting constants which plays so large a See also:part in modern geometrical researches . From this time Plucker's geometrical researches practically ceased, only to be resumed towards the end of his See also:life . It is true that he published in 1846 his System der Geometric See also:des Raumes in neuer analytischer Behandlungsweise, but this distinctions, however, are not maintained with much constancy. contains merely a more systematic and polished rendering of his P. domestica is a native of See also:Anatolia and the See also:Caucasus, and is See also:con-earlier results . In 1847 he was made professor of physics at sidered to be the only species naturalized in See also:Europe . P. insititia Bonn; and from that time his scientific activity took a new and is See also:wild in See also:southern Europe, in See also:Armenia, and along the shores of astonishing turn. the See also:Caspian . In the Swiss See also:lake-dwellings stones of the P . His first See also:physical memoir, published in Poggendorfs Annalen insititia as well as of P. spinosa have been found, but not those (1847), vol. lxxii., contains his great discovery of magnecrystallic of P. domestica . Nevertheless, the See also:Romans cultivated large See also:action . Then followed a See also:long See also:series of researches, mostly numbers of plums . The cultivated forms are extremely numerpublished in the same journal, on the properties of magnetic ous, some of the See also:groups, such as the greengages, the damsons and diamagnetic bodies, establishing results which are now part and the See also:egg plums being very distinct, and sometimes reproducand See also:parcel of our magnetic knowledge . In 1858 (Fogg . Ann. See also:ing themselves from See also:seed . The See also:colour of the See also:fruit varies from vol. ciii.) he published the first of his classical researches on the See also:green to deep See also:purple, the See also:size from that of a small See also:cherry to action of the magnet on the electric See also:discharge in rarefied gases. that of a See also:hen's egg; the form is oblong acute or obtuse at both Plucker, first by himself and afterwards in See also:conjunction with ends, or globular; the stones or kernels vary in like manner; and J . W . Hittorf, made many important discoveries in the spectro- the flavour, See also:season of ripening and duration are all subject to scopy of gases . He was the first to use the vacuum See also:tube with variation . From its hardihood the See also:plum is one of the most the capillary part now called a See also:Geissler's tube, by means of which valuable fruit trees, as it is not particular as to See also:soil, and the the luminous intensity of feeble electric discharges was raised See also:crop is less likely to be destroyed by See also:spring frosts . Prunes sufficiently to allow of spectroscopic investigation . He antici- and French plums are merely plums dried in the See also:sun . Their pated R . W . Y . See also:Bunsen and G . See also:Kirchhoff in announcing that the preparation is carried on on a large See also:scale in Bosnia and See also:Servia, lines of the spectrum were characteristic of the chemical sub- as well as in See also:Spain, See also:Portugal and southern See also:France . stance which emitted them, and in indicating the value of this Plums are propagated chiefly by budding on See also:stocks of the discovery in chemical See also:analysis . According to Hittorf he was See also:Mussel, See also:Brussels, St See also:Julien and See also:Pear plums . The damson, the first who saw the three lines of the See also:hydrogen spectrum, See also:wine-sour and other varieties, planted as See also:standards, are generally which a few months after his See also:death were recognized in the spec- increased by suckers . For planting against walls, trees which trum of the See also:solar protuberances, and thus solved one of the have been trained for two years in the nursery are preferred, mysteries of modern See also:astronomy, but See also:maiden trees can be very successfully introduced, and by Hittorf tells us that Plucker never attained great See also:manual liberal treatment may be speedily got to a fruiting See also:state . Any dexterity as an experimenter . He had always, however, -very See also:good well-drained loamy soil is suitable for plums, that of clear conceptions as to what was wanted, and possessed in a high See also:medium quality as to lightness being decidedly preferable. degree the See also:power of putting others in See also:possession of his ideas Walls with an See also:east or See also:west aspect are generally allowed to and rendering them enthusiastic in carrying them into practice. them . The See also:horizontal mode of training and the See also:fan or See also:half-fan Thus he was able to secure from the Sayner Hiftte in 1846 the forms are commonly followed; where there is sufficient height great electromagnet which he turned to such use in his magnetic probably the fan system is the best .
The shoots should be laid researches; thus he attached to his service his former See also:pupil the in nearly or quite at full length
.
The fruit is produced on small skilful mechanic Fessel; and thus he discovered and fully availed spurs on branches at least two years old, and the same spurs himself of the ability of the great See also:glass-blower Geissler. continue fruitful for several years
.
See also:Standard plum trees should
Induced by the encouragement of his mathematical See also:friends in be planted 25 ft. apart each way, and dwarfs 15 or 20 ft
.
The See also:England, Plucker in 1865 returned to the See also: Aug . See also:Jefferson b . Sept . See also:models to -be constructed which are now so well known to the Denniston's Superb . b . Aug . See also:Kirke's . . . m . Sept . student of the higher mathematics . He was engaged in bringing Oullin's See also:Golden . . . m . Aug . See also:Coe's GoldenDrop . . e . Sept . out a large work embodying the results of his researches in line Green-gage m.e.Aug . Reine See also:Claude de Bavay e . Sept . geometry when he died on the 22nd of .May 1868 . The work was b . Oct . so far advanced that his pupil and assistant See also:Felix See also:Klein was M'Laughlin's e . Aug . Ickworth Imperatrice b . Oct . Oct . able to complete and publish it (see GEOMETRY, LINE) . Among Angelina See also:Burdett b . Sept . See also:Late See also:Rivers . . . • Nov . the very numerous honours bestowed on Plucker by the various scientific See also:societies of Europe was the See also:Copley See also:medal, awarded to him by the Royal Society two years before his death . See R . F . A . Clebsch's obituary See also:notice (Abh. d. kon . Ges. d . Wiss. z . See also:Gottingen, 1871, vol. xvi.), to which is appended an appreciation of Plucker's physical researches by Hittorf, and a See also:list of Pliicker's works by F . Klein . See also C . I . See also:Gerhardt, Geschichte der Mathematik in Deutschland, p . 282, and Plucker's life by A . Dronke (Bonn, 1871) . |
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