MüLLER, JOHANN HEINRICH JACOB

(b. Kassel, Germany, 30 April 1809; d. Freiburg im Breisgau, Germany, 3 October 1875)

physics.

Müller’s father originally studied law, but gave it up to become, in 1807, a painter to the court of the prince of Waldeck. Johann Müller—as he unfortunately called himself in publications, thus creating confusion in bibliographies—inherited his father’s talent and excelled in illustrating his books. He spent his early years in Frankfurt am Main and Darmstadt, then, in 1829, enrolled in the University of Bonn to study mathematics and physics. His teachers included Karl von Münchow and Heinrich Plücker. In 1832 he entered Giessen University, where he attended lectures on chemistry, physics, and mathematics given by Heinrich Buff, Liebig, and Hermann Umpfenbach. He received the Ph.D. in 1833 with a thesis on the optics of crystals. In 1837 he became a teacher at the Giessen Realschule and was eventually, in 1844, appointed professor of physics and technology at the University of Freiburg.

Early in his career Müller developed a systematic concept of physics which was partially determined by his didactic talent. He wrote a number of synopses (see Bibliography) before his appointment at Freiburg and from 1842 he edited his work Lehrbuch der Physik und Meteorologie. The subsequent enlargements of this work, which remained well-known until the 1930’s, constituted Müller’s principal activity for the rest of his life.

When the University of Freiburg ended the mandatory study of physics in 1836 Müller attempted to attract students by improving the instruction. He purchased and built many improved instruments for the laboratory and asked Lerch to draw large-scale illustrations for his lectures. During the university’s summer term Müller lectured on statics of solids, fluids, and aeriform bodies; acoustics; heat; electricity; and magnetism. His winter lectures comprised wave mechanics and optics, his preferred subjects. He also introduced experimental practice in physics and in 1850 the first doctorate was awarded.

Müller conducted research into optics, magnetism, and light and heat radiation. Applying George Airy’s theory to crystal optics, Müller calculated the isochromatic curves of plates of crystals with one parallel optical axis; he also calculated the black hyperbolic beams in the system of lemniscates of crystals with two axes. In 1849 he experimentally found, independently of Joule, the limits of intensity of the magnetism (m) of iron, which according to Siméon Poisson, Heinrich Lenz, and Carl Jacobi should have been proportional to the magnetizing force (ρ). Müller’s findings were more precise than Joule’s results, and he calculated ρ ∞ an m for a constant diameter of the rod, a relation subsequently used with success.

From 1846 Müller studied Fraunhofer lines, an investigation that led him to explore ultraviolet radiation by fluorescence; with the chemist Lambert Babo, he was able to measure, in 1855, the first Fraunhofer lines beyond the violet end of the spectrum. He then examined the Thermische Wirkungen des Sonnenspectrums (“infrared spectrum”) by drawing upon the work of Rudolph Franz, who first measured the infrared spectrum quantitatively by heat transmission (1856). This process, known as “diathermancy,” plus the analysis of the spectrum with rocksalt and the use of a linear thermopile to determine the spectral energy, permitted Müller to draw a curve of the intensity of radiation by heat effect. This was the first such curve ever to be drawn. Müller thus proved, contrary to Antoine Masson and Jules Jamin, that the maximum of heat energy lies in the dark region. He also found the wavelength of the rays on the extreme end of the spectrum to be 0.0048 mm. Although it was impossible to take a curve in the diffraction of heat because of the energy distribution by diffraction, Müller construed the curve geometrically from the prismatic spectrum and concluded that the heat spectrum is three times as extensive as the visible one.

Müller’s most significant textbook, the Lehrbuch, first appeared as Pouillet’s Lebrhuch der Physik und Meteorologie, a “free adaptation” of the 1837 edition of C. S. Pouillet’s Éléments de physique expérimentale et de météorologie. Maüller’s innovations included numerous woodcuts inserted directly into the text, whereas Pouillet had inserted copper-plate engravings after the text. The illustrations of the apparatus were particularly useful for the mechanician. The book was initially styled for the nonphysics major. He supplied the derivations of mathematical formulas and stressed mechanical theorems. Müler incorporated Gauss’s works on magnetism for the first time and recast the chapters on galvanism, light, and meteorology. Each of the seven editions that were published during his lifetime underwent considerable emendation. A third volume, Lehrbuch der Kosmischen Physik, based upon Müller’s own observations was added in 1856. A supplement. Die medizinische Physik, edited by A. Fick, also appeared in the same year. The rapid evolution in physics was characteristically reflected by the “Reports on the Most Recent Developments in Physics,” edited by Müller in 1849.

Liebig’s letters of 1844 induced Müller to edit Physikalische Briefe für Gebildete aller Stände, a new edition of Euler’s Letters to a German Princess. Müller subsequently added a third and fourth part; there, in his own letters on physics, he was emphatic that natural sciences taught objective truth, the limits of man’s intellectual power, and tolerance. Müller encouraged the criticism of traditional preoccupations. He read many papers before the Naturforschende

Gesellschaft zu Freiburg im Breisgau and helped to extend the society’s activity into physics.

BIBLIOGRAPHY

I. Original Works. MS documents on Müller’s employment at Freiburg are in the university archive. A letter to an unknown person, 3 April 1843, is in the Germanisches Nationalmuseum, Nuremberg, Germany; 6 letters to Karl Mohr, 30 December 1838, 1 January 1848, 30 April 1848, 4 August 1862, 1 April 1868, and 17 April 1868, are at the University of Bonn. The Staatsbibliothek Preussischer Kulturbesitz, Berlin, contains one letter to an unknown person, 15 October 1843, one letter to Peter Riess, 30 September 1856, and one letter to an unknown person (perhaps Steeg), 9 September 1873.

Müller’s dissertation was Erklärung der isochromatischen Curven, welche einaxige parallel mit der Axe geschnittene Krystalle im homogenen polarisirten Lichte zeigen (Darmstadt, 1833); his main synopses are Kurze Darstellung des Galvanismus (Darmstadt, 1836); Elemente der ebenen Geometrie (Darmstadt, 1838); Elemente der ebenen Trigonometrie (Darmstadt, 1838); Elemente der sphärischen Trigonometrie (Darmstadt, 1840); Pouillet’s Lehrbuch der Physik und Meteorologie, für deutsche Verhältnisse frei bearbeitet, 2 vols. (Brunswick, 1842–1844); a second ed. (Brunswick, 1844–1845), with subtitle Lehrbuch der Physik und Meteorologie, includes about 1,000 woodcuts; the eleventh and final ed., 13 pts. in 5 vols., was published in Brunswick in 1926–1935; extended by the third volume, Lehrbuch der Kosmischen Physik (Brunswick, 1856), and by a supplement edited by A. Fick, Die medizinische Physik (Brunswick, 1856).

Subsequent writings are Grundzüge der Krystallographie (Brunswick, 1845); Grundriss der Physik und Meteorologie. Für Lyceen, Gymnasien, Gewerbe- und Realschulen, sowie zum Selbstunterrichte (Brunswick, 1846); Mathematischer Supplementband zum Grundriss der Physik and Meteorlogie (Brunswick, 1860); Physikalische Briefe für Gebildete aller Stände von Leonhard Euler und Dr. Johann Müller, edited by Müller, contains a third part, Die neuesten Ergebnisse und Bereicherungen der Physik in Briefform behandelnd (Stuttgart, 1847–1848), and a fourth part (Stuttgart, 1854) edited by Müller; Bericht über die neuesten Fortschritte der Physik, in ihrem Zusammcnhange dargestellt, 2 vols. (Brunswick, 1849–1851), with an English trans, in Report of the Board of Regents of the Smithsonian Institution, (1856), 311–423; (1857), 357–456; (1858), 333–431; (1859), 372–415; Die constructive Zeichnungslehre, oder die Lehre vom Grundund Aufriss, 2 parts (Brunswick, 1865); Die Schule der Physik. Eine Anleitung zum ersten Unterricht in der Naturlehre (Brunswick, 1874); Müller was an editor of Berichte über die Verhandlungen der Gesellschaft für Beförderung der Naturwissenschaften zu Freiburg im Breisgau (from vol. 2 on entitled Beriehte über die Verhandbtngen der naturforschenden Gesellschaft…, ed. by Müller et at.), of which vol. 1 (1855) contains a number of his papers.

Papers cited in the article are “Berechnung der hyperbolischen dunkeln Büschel, welche die farbigen Ringe zweiaxiger Krystalle durchschneiden,” in Annalen der Physik120 (1838), 273–291; “Fraunhofer’sche Linien auf einem Papierschirm,” ibid., 145 (1846), 93–115; “Anwendung der stroboskopischen Scheibe zur Versinnlichung der Grundgesetze der Wellenlehre,” ibid., 143 (1846), 271–272; “Entwickelung der Gesetze des Elektromagnetismus,” repr. from Bericht über die neuesten Fortschritte, 1 , 494–538, with a defense of his statement on saturation of magnetism (Brunswick, 1850); “Photographirte Spectren,” in Annalen der Physik173 (1856), 135–138; “Die Photographie des Spectrums,” ibid., 185 (1860), 151–157; Programm, wodurch zur Feier des Geburtsfestes Seiner Königlichen Hoheit…Grossherzogs Friedrich…einiadet der gegenwärtime Protector Dr. J. Müller (Freiburg im Breisgau, 1858), which contains a sketch of the Geschichte…des physikalischen Kabinets of Freiburg University; “Untersuchungen über die thermischen Wirkungen des Sonnenspectrums,” repr. in Annalen der Physik181 (1858), 337–359, 543–547; and “Rutherfurd’s Photographie des Spectrums,” ibid., 202 (1865), 435–440. For a bibliography of Müller’s papers see Annalen der Physik, Namenregister und Sachregister 1875; and Poggendorff (not always exact), II, 228–229; III, 944; VI, 1799. A bibliography of his books is given in W. Heinsius, 10 (1849), III, 124; British Museum, Catalogue of Printed Books; Catalogue Général de la Bibliothèque Nationale, Paris.

II. Secondary Literature. The only biographical sketch is Emil Warburg, Gedächtnisrede auf Johann Heinrich Jacob Müller bei dessen academischer Todtenfeier am l6, Juli 1877 (Freiburg im Breisgau, 1877), repr. in large part in Friedrich von Weech, ed., Badische Biographien, III (Karlsruhe, 1881), 114–121; on Müller’s activities at Freiburg see Hans Kangro, “Die Geschichte der Physik an der Universität Freiburg,” MS copy (1954) deposited at Freiburg University, pp. 77–89.

Hans Kangro