MOHN, HENRIK

(b. Bergen, Norway, 15 May 1835; d. Christiania [now Oslo], Norway, 12 September 1916)

meteorology, oceanography.

Mohn became interested in science during his first year at the University of Christiania, where in 1858 he received his master’s degree in mineralogy. Soon afterward he wrote a prize essay on the position of cometary orbits and became assistant professor of astronomy. In 1866 he was appointed director of the new Norwegian Meteorological Institute, which under his guidance grew into an important organization with 450 stations all over the country. From 1866 to 1913 he occupied the first chair of meteorology at the University of Christiania.

Mohn’s many endeavors in practical meteorology resulted in a very wide range of publications. A series of annual bulletins and other reports and climatic tables for Norway were written or edited by him. Particular works dealt with thunderstorms, fog signals, and other subjects. He also perfected the hypsometer for measuring altitude by the boiling point of water.

With G. O. Sars, Mohn planned the Norwegian North Atlantic expeditions, participating in the three voyages that occupied the summers of 1876, 1877, and 1878. He edited the general report and wrote the sections on meteorology and oceanography. He also edited the meteorological data from Nansen’s Fram expedition through the Northwest Passage of 1893–1896, from the Arctic expedition of 1898–1902, and from Amundsen’s South Pole expedition of 1912–1913. Beginning in 1870, Mohn became very active in international organizations. At his death he was recognized as the grand old man of European meteorology.

Mohn was not only a brilliant empiricist, but also deeply interested in theory. His studies, with C. M. Guldberg, on the motions of the atmosphere (1876 –1880) utilized the Coriolis law and also took into account friction between the atmosphere and the earth. The Mohn-Guldberg equations meant a breakthrough for dynamical meteorology and gave the first (although incomplete) theoretical foundation of the work begun by Buys Ballot, William Ferrel, and others. The new ideas were propagated in a book which, from a small and rather popular Norwegian version, developed into a comprehensive manual of meteorology that was translated into several languages.

BIBLIOGRAPHY

I. Original Works. Mohn’s writings include Om Kometbaners indbyrdes Beliggenhed (Christiania, 1861), trans, into French as Mémoire sur la situation réciproque des comètes (Christiania, 1861); Norsk meteorologisk Aarbog (Christiania, 1867 ff.); Det Norske Meteorologiske Instituts Storm Atlas, Atlas des tempètes (Christiania, 1870); “Om Vind og Vejr,” in Folkevennen, (1872), ; Grundzüge der Meteorologie (Berlin, 1875, 1879, 1883), trans. into Finnish (Helsinki, 1880) and into French (Paris, 1884); études sur les mouvements de l’atmosphère, 2 vols. (Christiania, 1876–1880), written with C. M. Guldberg; Den Norske Nordhavs-Expedition 1876–1878. The Norwegian North Atlantic Expedition. General Report (Christiania, 1880); “Studien über Nebelsignale,” in Annalen der Hydrographie and maritime Meteorologie 1882, 1893, 1895); Den Norske Nordhavs-Expedition 1876–1878.… Meteorology (Christiania, 1883); Nordhavets Dybder, Temperatur og Stromninger (Christiania, 1887); Tordenbygernes Hyppighed i Norge 1867–83 (Christiania, 1887); Les orages dans la peninsule scandinave (Uppsala, 1888), written with H. H. Hildebrandsson; Om Taagesignaler (Christiania, 1897); “Das Hypsometer als Luft-druckmesser und seine Anwendung zur Bestimmung der Schwerekorrektion,” in Skrifter … det Norske videnskapsakademi i Oslo, Math.-naturvis. K1. (1899); and “Neue Studien über das Hypsometer,” in Meteorologische Zeitschrift (1908).

II Seconday Literatue. See V. Bjerknes, Meteorologien in Norge (Christiania, 1917); the unsigned Christian Joachim Mohn, hans forfaedres liv og efter-kommere (Oslo, 1928), 318 ff.; and T. Hesselberg, “Mohn, Henrik,” in Norsk Biografisk Leksikon, IX (Oslo, 1939), 290 ff.

Olaf Pedersen