Julius Plücker

Julius Plücker (1801 to 1868) was a German mathematician and physicist, born at Elberfeld, now part of Wuppertal. He was educated at Düsseldorf and at the universities of Bonn, Heidelberg and Berlin, went to Paris in 1823 to learn from the French geometers, and returned to Bonn in 1825, where he became professor of mathematics in 1828. His Analytisch-geometrische Entwicklungen introduced the method of abridged notation and, in its second volume of 1831, established projective duality on an independent basis. Made professor of physics at Bonn in 1836, he turned to experiment and in 1858, working with the vacuum tubes of his colleague Heinrich Geissler, published his first researches on the action of a magnet on the electric discharge in rarefied gases, finding a fluorescent glow on the glass that moved under a magnetic field and that was later shown to come from cathode rays. With Johann Hittorf he made important discoveries in the spectroscopy of gases and held that spectral lines are characteristic of the emitting chemical substance.