Lorenz, Hans

(b, Wilsdruff, Germany, 24 March 1865;d. Sis trans, near Innsbruck, Austria, 4 July 1940)

mechanics, mechanical engineering.

The son of a teacher, Lorenz grew up in Leipzig, then studied (1885–1889) mechanical engineering at the Dresden Polytechnic Institute, where Gustav Zeuner was his principal teacher. His first professional experience (1890–1893) was with the Augsburg firm f L. A. Riedinger, developing a pneumatic power distribution system, and with the Escher-Wyss Company of Zurich, improving refrigeration compressors (1893–1894).

In 1894 Lorenz established himself in Munich as an independent consulting engineer. He founded, and for the first five years edited, the Zeitschrift für die gesamte Kälteindustrie,, which quickly became the leading international journal of refrigeration technology. In 1894 he received a Ph.D. from the University of Munich—a rare feat then for an engineer—with a dissertation on the thermodynamic limits of energy conversion.

Lorenz’ academic career began with brief appointments as extraordinary professor of applied science at Halle (1896) and Göttingen (1900). In Göttingen he was also director of the Institute for Technical Physics, which had recently been established upon recommendation of the mathematician Felix Klein, and which was to become world famous under Lorenz’ successor, Ludwig Prandtl. In 1904 Lorenz was appointed to the chair of mechanics at the newly founded Technische Hochschule of Danzig, a position that he held for the rest of his active career. He also served as director of its materials testing laboratory (from 1909) and as rector (1915–1917). After his retirement in 1934, Lorenz lived in Munich and Sistrans.

Whether any of Lorenz’ research efforts will be remembered in history is difficult to judge. Without doubt, however, he was an important figure in his own time. He was active in three areas of engineering: practice, teaching, and research. He was sought as a consultant in the burgeoning refrigeration industry, and his professional leadership was recognized in his election to presidencies and honorary memberships scientific societies. As an engineering he was a leading proponent of a distinctive style of scientific engineering that flourished in early twentieth-century Germany, It was his belief that a creative engineer combined mathematical and scientific competence of a high order with the ability to translate actual problems into simple, tangible models (and was occasionally willing to sacrifice mathematical rigor for the sake of practical results). For undergraduates, Lorenz was a difficult teacher, but his advanced courses, as many of his former graduate students (prominent among whom are W. Hon, R. Plank, and A. Pröll) have testified, were unforgettable.

Lorenz’ original research is characterized by unbounded versatility. His topics derived from his own engineering practice (pneumatic transmission lines, refrigeration), from his work as head of the materials testing laboratory (buckling, plastic deformation), and from ongoing scientific debates (vibrations, gyroscopes, turbomachinery, turbulent flow), to the war effort (ballistics). In his later years he published a considerable amount of work on astrophysics and astronomy.

BIBLIOGRAPHY

I. Original Works. An almost complete list of Lorenz’ scientific papers (approximately 130 items) is given in Poggendorff. His books are Neuere Kühlmaschinen (Munich, 1896); Dynamik der Kurbelgetriebe (Leipzig, 1901), with O. Schlick; Lehrbuch der technischen Physik, 4 vols. (Munich, 1902–1913); Neue Theororie and Berechnungder Kreiselräder (Munich, 1906); Einführung in die Elemente der höheren Mathematik und Mechanik (Berlin, 1910); Ballistik (Munich, 1917); Technische Anwendungen der Kreiselbewegungen (Berlin, 1919); Einfühnmg in die Technik (Leipzig, 1919); and Das Verhalten fester Körper im Fliess-bereich (Leipzig, 1922). Lorenz left unpublished MSS of an autobiography, “Praxis, Lehre, und Forsehung: Akade-mische Erinnerungen und Erfahrungen” (ca. 1935) and of a book on astronomy (ca. 1938).

II. Secondary Literature. Biographical writings on Lorenz consist of birthday tributes and obituaries, the most extensive being by Rudolf Plank, “Hans Lorenz zum 70. Geburtstag,” in Zeitschrift für die gesamte Kälte-Industrie,42 (1935), 42–46. See also G. Cattaneo, “Was ich Hans Lorenz verdanke,” ibid.,47 (1940), 114; Wilhelm Hort, “Hans Lorenz zum 70. Geburtstag,” in Zeitschrift für technische Physik,16 (1935), 93–95; R. Plank, “Hans Lorenz zum 75. Geburtstag,“ibid.,47 (1940), 33; and “Hans Lorenz,” in Zeitschrift des Vereins deutscher Inge-nieure,84 (1940), 638; and A. Pröll, “zu Geheimrat Lorenz’ 70. Geburtstag,” in Zeitschrift für angewandte Mathematik und Mechanik,15 (1935), 183–184.

Otto Mayr