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Arthur König
Arthur König
Born	13 September 1856; Krefeld
Died	26 October 1901 (aged 45); Berlin

Arthur Peter König (13 September 1856, Krefeld – 26 October 1901, Berlin) devoted his short life to physiological optics. Born with congenital kyphosis he studied in Bonn and Heidelberg, moving to Berlin in the fall of 1879 where he studied under Hermann von Helmholtz, whose assistant he became in 1882. After obtaining a doctoral degree in 1882 he qualified for a professorial position in 1884. In 1890 he became director of the physical department of the Physiological Institute of the University of Berlin. In the same year he married Laura Köttgen with whom he had a son, Arthur, who became an astronomer. Circulatory problems caused by his kyphosis resulted in his premature death in 1901.^[1]

Originally working in physics, he began in 1883 to concentrate on physiological optics where he published over thirty papers, some of seminal importance. Among these are the 1886 paper (together with Conrad Dietrici) Fundamental sensations and their sensitivity in the spectrum, an empirical determination of what in fact is the spectral sensitivity of the human rod and cone sensors of vision.^[2]

Earlier attempts at such measurements, but based on much simpler technology, had been made in 1860 by the English physicist James Clerk Maxwell (1831–1879). Using newly development spectrophotometric equipment and modifications of the experimental procedure König and Dieterici published a more detailed paper in 1892, determining the "fundamental sensations" not only of subjects with normal color vision (trichromats) but also of dichromats and monochromats.^[3]

With these measurements König provided evidence for the conjecture that the most common form of color blindness, dichromacy, is due to the absence of one cone type in the eye. Averaged König functions were widely used in psychophysical color stimulus calculations until new data based on a slightly different method and involving many more observers were determined by J. Guild and W. D. Wright in the later 1920s, resulting in the recommendations of standard observer data by the Commission Internationale de l'Eclairage (CIE, International Commission on Illumination) in 1931.

Fundamental color sensations as a function of wavelength, from ^[2]

Other important investigations involve the sensitivity of the normal eye for differences in wavelength of light,^[4] dependence of the Newton/Grassmann laws of color mixture on light intensity,^[5] validity of Fechner's law at different light intensities,^[6] brightness of spectral hues at different light intensities, ^[7] and the similarity between the perceptual sensitivity of the rod cells and the absorption spectrum of the rod photopigment, rhodopsin.^[8]

König was very active as an editor. In 1889 he became the sole editor of Verhandlungen der Deutschen Physikalischen Gesellschaft. From 1891 on, together with the psychologist H. Ebbinghaus, he edited the journal Zeitschrift für Psychologie und Physiologie der Sinnesorgane. After Helmholtz's death in 1894 König took on the task of completing preparations for the second edition of the former's Handbuch der physiologischen Optik (1896, Treatise on physiological optics)^[9] to which he added a bibliography of vision consisting of nearly 8,000 titles.

König's 32 papers on physiological optics were published posthumously in book form in 1903.^[10]

References

^ Source of biographical information: M. Richter, Arthur König zum Gedächtnis, Die Farbe 5 (1956) No.1/2, 1–6.
^ ^a ^b A. König, Die Grundempfindungen und ihre Intensitäts-Vertheilung im Spectrum, Sitzungsberichte der Akademie der Wissenschaften zu Berlin, 29 July 1886, 805–829.
^ A. König, Die Grundempfindungen in normalen und anomalen Farbsystemen und ihre Intensitätsvertheilung im Spectrum, Zeitschrift für Psychologie und Physiologie der Sinnesorgane 4 (1892) 241–347.
^ A. König, Ueber die Empfindlichkeit des normalen Auges für Wellenlängen-unterschiede des Lichtes, Annalen der Physik und Chemie 22 (1884) 579–589.
^ A. König, Ueber Newton's Gesetz der Farbenmischungen, Sitzungsberichte der Akademie der Wissenschaften zu Berlin 31 March, 1887, 311–317.
^ A. König, Experimentelle Untersuchungen über die psycho-physische Fundamentalformel in Bezug auf den Gesichtssinn, Sitzungsberichte der Akademie der Wissenschaften 26 July, 1888, 917–931.
^ A. König, Ueber den Helligkeitswert der Spectralfarben bei verschiedener absoluter Intensität, Beiträge zur Psychologie und Physiologie der Sinnesorgane, 1891, 309–388.
^ A. König, Ueber den menschlichen Sehpurpur und seine Bedeutung für das Sehen, Sitzungsberichte der Akademie der Wissenschaften zu Berlin, 21 June 1894, 577–598.
^ H. von Helmholtz, Handbuch der physiologischen Optik, 2nd ed., Hamburg: Voss, 1896.
^ A. König, Gesammelte Abhandlungen zur physiologischen Optik, Leipzig: Barth, 1903.