travel constantly between various weather stations in Germany, on the Balkans, on the Western Front and in the Baltic region. Nevertheless, he was able in 1915 to complete the first version of his major work, Die Entstehung der Kontinente und Ozeane (“The Origin of Continents and Oceans”). His brother Kurt remarked that Alfred Wegener's motivation was to “reestablish the connection between geophysics on the one hand and geography and geology on the other, which had become completely ruptured because of the specialized development of these branches of science.” Interest in this small publication was however low, also because of wartime chaos. By the end of the war Wegener had published almost 20 additional meteorological and geophysical papers in which he repeatedly embarked for new scientific frontiers. In 1917 he undertook a scientific investigation of the Treysa meteorite. Postwar period In 1919, Wegener replaced Köppen as head of the Meteorological Department at the German Naval Observatory (Deutsche Seewarte) and moved to Hamburg with his wife and their two daughters. In 1921 he was moreover appointed senior lecturer at the new University of Hamburg. From 1919 to 1923 Wegener did pioneering work on reconstructing the climate of past eras (now known as "paleoclimatology"), closely in collaboration with Milutin Milanković, publishing Die Klimate der geologischen Vorzeit (“The Climates of the Geological Past”) together with his father-in-law, Wladimir Köppen, in 1924. In 1922 the third, fully revised edition of “The Origin of Continents and Oceans” appeared, and discussion began on his theory of continental drift, first in the German language area and later internationally. Withering criticism was the response of most experts. In 1924 Wegener was appointed to a professorship in meteorology and geophysics in Graz, a position that was both secure and free of administrative duties. He concentrated on physics and the optics of the atmosphere as well as the study of tornadoes. He had studied tornadoes for several years by this point, publishing the first thorough European tornado climatology in 1917. He also posited tornado vortex structures and formative processes. Scientific assessment of his second Greenland expedition (ice measurements, atmospheric optics, etc.) continued to the end of the 1920s. In November 1926 Wegener presented his continental drift theory at a symposium of the American Association of Petroleum Geologists in New York City, again earning rejection from everyone but the chairman. Three years later the fourth and final expanded edition of “The Origin