These large polar oscillations were incompatible with the Milankovich theory, which required that Earth’s pole of rotation should have changed its angle relative to the ecliptic (axial tilt, or obliquity of the ecliptic) by a very small amount: an oscillation of 2.4°, between 22.1° and 24.5°. This was required for the intersection (amplification or damping) of the various astronomical parameters controlling the amount of solar radiation reaching Earth’s surface: any large excursion of the pole of rotation relative to the fixed stars—an astronomical pole shift—would have destroyed Milankovich’s entire hypothesis.
The relationship in Wegener’s theory between apparent motions of the pole and absolute motions of the pole—in conjunction with absolute movements of the continents and their motion relative to an Africa fixed in place—was one of the murkiest points of his theory and the most difficult to understand. Wegener believed in what we would now call “true polar wander,” in which rearrangement of continental blocks could cause rapid and large excursions of Earth’s pole of rotation, so that its pole of figure might coincide once again with its pole of inertia. Nowhere in his theory of the origin of continents and oceans (up to 1924) does Wegener make it at all clear whether his absolute polar motions are also astronomical, though his book often reads as if they are.
It would seem on the face of it that when Wegener says, as he did in 1922, that the data give “a North Pole at the beginning of the Tertiary in the neighborhood of the Aleutian Islands and from then a migration toward Greenland where it is to be found in the Quaternary,” we are talking about a very large axial shift in a very short period of geological time, in which Earth’s pole of inertia moved 10° or more and Earth’s pole of figure raced to catch up with it.90
It is difficult to imagine this as other than an astronomical shift, since Wegener moved so firmly to contrast his theory of real pole shifts caused by separate continental motions with the theory of Kreichgauer, and earlier of John Evans, of the shift of the whole crust over the whole interior—a massive relative shift leaving the astronomical pole unchanged. On the other hand, Wegener had characterized the earlier history of Earth, of Pangäa, as a motion of the entire Sial sphere westward over the Sima sphere, and he had even speculated, as late as 1921, that the Atlantic split had been caused by the drag of the thicker Asian trailing side of the Pangäa continent, which allowed the Americas to break away and open the Atlantic. In 1924 these contradictions and confusions remained unresolved.
In order to bring his half of the book into correspondence with Köppen and Milankovich’s half of the book, Wegener found it expedient and necessary to discard all the oscillations of the North Pole in the Petermanns map of 1921 and to push the extensive Tertiary excursions of Earth’s pole of rotation back in time to the Pliocene and Early Quaternary. Moreover, because of the linkage in his theory between the motions of the pole and the motions of the continents, this meant that Wegener had also to move the opening of the North Atlantic back in time to the Pliocene, and even the Miocene. Indeed, his maps on pages 116 and 117 show the separation of Greenland from Canada and of Iceland from both Canada and Europe as already taking place in the later Tertiary. Additionally, these maps give a greater apparent distance between North America and Europe than that between South America and Africa in the Miocene. This is a very different picture of the timing and geometry of the continents than in any of his earlier versions of his theory, in which he insisted that the Atlantic had opened from south to north.91
Changing the theory in this direction did have advantages for Wegener, although neither here in Klimate der geologischen Vorzeit nor in any other venue in 1923 or 1924 did he announce it: he just changed it. Nature had reported in January 1923 that in the British meeting at Hull the previous September (1922) the only point of universal agreement was that Wegener had moved the major shift of continents in the Northern Hemisphere too far forward into the ice ages; everyone had found this improbable. Even scientists very much predisposed to accept Wegener’s ideas, like Schweydar in 1921 at Berlin, had urged him to “slow down.” He had done this for earlier periods by 1922, but not yet for the Quaternary. Now (in 1924) that Wegener assumed a stability of the pole of rotation throughout most of the past half-million years (the period of the great ice ages), it became much easier to keep the distance between Siberia and Alaska constant, or even diminishing, as North America rotated away from Greenland and Europe around a fixed rotational and inertial pole: if the changes were longitudinal and rotatory, there was no reason for the pole-fleeing force to act, and no reason for the continental shifts to cause a new pole position.
In retrospect, it is not clear how Wegener could have announced this major change in his theory. After all, the presentation of the “climates of the past” was to proceed by “assuming the correctness of Wegener’s theory of continental displacements,” and it is difficult to assume the correctness of a theory if that theory is undergoing major modifications at the time you are assuming its correctness. This is not impossible to do, but it is an unlikely premise for such an undertaking. Moreover, this relocation of the time of separation of the northern continents back into the Tertiary really did unseat the original areas of agreement between Wegener and Köppen in 1918. Köppen had found Wegener’s theory of continents compelling not least because the clustering of Northern Hemisphere continents allowed a reconstruction of the southern borders (the terminal moraines) of the Quaternary ice sheets as a continuous line around a single northern paleocontinent. In Wegener’s new construction of continental displacements, there had been considerable dispersal of the various Northern Hemisphere continental fragments before the ice age even began.
Köppen and Wegener’s graphical rendering of Milankovich’s calculations of the amount of sunlight reaching Earth in summer in high latitudes. Milankovich calculated the amounts for latitudes 55°, 60°, and 65° north at 10,000-year intervals from 650,000 BP to the present. These curves are shown as I, II, and III at the top of the map. Curves IV and V show (once again), in the dark line, the approximate value of solar radiation at 65° in the Northern and Southern Hemispheres, respectively. This line is superimposed on curves for the ecliptic angle (dashed line) and the eccentricity of the orbit times the longitude at perihelion (lighter solid line). The diagram aims to show that the last four glacial maxima coincide with the last four minima of summer sunshine, based on the reinforcing effect of the astronomical parameters, visible in the diagram. From Köppen and Wegener, Die Klimate der geologischen Vorzeit.
Wegener probably made these changes in the spring or summer of 1923. He would not by then have been finished with his mapping of Earth history, but Milankovich had completed his calculations in the late winter and early spring of 1923, and Wegener, Köppen, and Milankovich would have been working out the best way to graph the results at about this time. Milankovich’s results were breathtaking when mapped against the geological record of advance and retreat of the ice sheet prepared by Albrecht Penck and Eduard Brückner (1862–1927)—the correspondences between ice maxima and “astronomically forced” solar minima were nearly perfect.
Wegener, ready as usual to surrender a theoretical idea in the face of convincing data, was willing to allow that during the Quaternary, for some reason or another, oscillations of the pole had been damped out over a period of a half-million years. In his larger scheme, this was no problem, because the earlier great excursions of the pole in the Tertiary were, he surmised, a response to the “flight from the poles” of continental fragments which had caused the great equatorial compression producing the Alps, Himalayas, and other mountains. His theory was flexible enough to encompass this change. As Argand had said, Wegener’s theory reflected “the protean resistance of a plastic universe” to any general refutation.
The Call to Graz
In the winter of 1923, Heinrich von Ficker made good his promise of the previous autumn and resigned his professorship in Graz in order to accept the professorship in Berlin as Hellmann’s succesor. The Graz
faculty commission met on 9 March 1923 and recommended that Wegener be listed first as Ficker’s successor. Their report speaks of Wegener’s versatility, his success in many fields, his comprehensive training in physics and astronomy, his astonishing industry (erstaunlichen Fleiße), and his aptitude and productivity in the realm of meteorology.92 It was at this meeting that it was decided not to list Victor Conrad, because of the growing anti-Semitic feeling in Graz and the near certainty that when the list was announced for the “call,” if Conrad’s name were on it, student groups would rise up in public opposition.
There were complications with the appointment, however, on Wegener’s side. There was some difficulty over whether the call would go out as an appointment for an ordinary (full) professor or an extraordinary (associate) professor at a lower salary, with a contractual promise that within a few years the professorship would be converted via promotion to a full professorship. Wegener seems to have balked at this, though there’s some confusion about the issue. Helmut Flügel, the leading authority on Wegener’s tenure in Graz, says that Wegener actually wanted the call as extraordinary professor so that he could avoid administrative work. This seems improbable, in light of Wegener’s letter in July 1923 to the Education Ministry in Vienna, in which he said he had serious reservations about accepting a call at that rank, “since I already occupy such a position at the University of Hamburg.” Moreover, the salary offered was less than his salary as head of the meteorological division at the German Marine Observatory.93
The negotiations dragged on for the rest of 1923, while Wegener worked on the climate book with Köppen—when he could find the time away from his punishing schedule at the observatory and his teaching at the university. In the winter semester 1922/1923 he had given a course on the thermodynamics of the atmosphere, and in the summer semester 1923 a course on introduction to meteorology. These were offered in anticipation of the call to Graz and his need to have lectures in hand that were up to date. The difficulty of the negotiations with Graz is perhaps expressed in his turn away from introductory meteorology for the semester beginning in fall 1923 at Hamburg, with a return to a course in climatology. Wegener would not go to Graz except on his own terms, and things looked rather dark in the fall of 1923. If he were not going to Graz, he could at least support his climate research with his teaching at Hamburg.94
Wegener insisted that he be appointed as a full professor and that his salary be adjusted to reflect that he had already been (at Marburg, Dorpat, and Hamburg) an extraordinary professor for six years, and he insisted that for purposes of calculating his pension all his years of government service be counted back to his first year as an assistant at the Lindenberg Observatory eighteen years before. Else thought he was crazy to insist on this, and Felix Exner and Eduard Brückner in Vienna pleaded with him to back off on his demands, since his rank and salary would automatically rise within a year or two, saying that if he continued to be so “stiff-necked” about this he would ruin everything (die ganze Sache aufs Spiel setze).95
Negotiations between Wegener and the Austrian Education Ministry in Vienna had dragged on for nearly a year when in March 1924, to everyone’s surprise, the ministry gave into all of Wegener’s demands: a full professorship, a higher salary, and a pension benefit calculated from the time of Wegener’s assistantship in Lindenberg in 1906.96 The matter of the pension was of greater psychological import than even the salary for Wegener. He could remember that in 1906, when he had decided to go to Greenland with Mylius-Erichsen, his father had railed at him that instead of flying around in balloons and running off to the North Pole, he should be finding “pensioned employment,” marrying, settling down, and starting his career. The other parts had come first: he had married, he had pursued his career relentlessly, and now he would finally be settled down, a full professor, pensioned at the same level as if he had taken his father’s advice in 1906.
Alfred and Else were elated; the appointment would begin almost immediately, on 1 April 1924. Alfred would travel to Berlin to deliver his resignation from the Naval Observatory, and he wrote ahead to Ficker to tell him that he wanted to stop by and thank him in person. “This is the fulfillment of a wish I have had for as long as I can remember. If the education ministry knew how much I wanted the job in Graz, they wouldn’t have given me even 12 years worth of pension benefit.”97
Else accompanied him to Berlin and on the trip south to Graz. When they arrived in Graz, Else was stunned. Spring was so much farther ahead than it had been in Hamburg. The city was full of trees, the trees were full of birds, and there were parks everywhere. They climbed the clock tower and looked out over the city, and everywhere they looked they saw gardens. The Karl-Franzens University campus, unlike its brash, makeshift counterpart in Hamburg in the early 1920s, was architecturally unified, graceful, peaceful, and calm.98
They began immediately to look for a place to live, in the residential neighborhoods closest to the university. After years of train and streetcar travel, Alfred was determined to walk to work, as he had in Marburg. They hoped to buy a detached house but had no luck finding one in the first few days. Most of the owners were interested in a sale that contained a “swap” in which most of the cost of purchase would be made up by title to another house; there was considerable uncertainty about the stability of currency and a consequent conservatism among those who held real property.99
They needed a detached house with a lot of space rather than an apartment. During the protracted negotiations for the professorship, Alfred and Else had long discussions with her parents about what would happen if they should move. The Köppens had a large family, and the Hamburg house had long been a refuge for those having trouble, as well as a site for happy homecoming on holidays. But the unexpected death of one of Else’s brothers and the decision of one of her sisters to move her family south to Bulgaria would leave the elder Köppens quite alone in Hamburg, if the Wegener family were to move away. They decided that if Alfred should win the professorship in Graz, they would all move together. Alfred and his father-in-law had a friendship and collaboration they were unwilling to sever, and having the grandparents around gave Alfred and Else a freedom of movement they could never achieve otherwise.
After a few days of looking, it was clear that nothing was available in April 1924, and Alfred moved into furnished rooms and began to write his lectures; to receive the salary of a professor beginning 1 April, he had to be in residence in Graz, though he thought he would not begin his full program of teaching until the fall of 1924. There was nothing to do but for Else to return to Hamburg without him and to set about finding a buyer for the house in the Violastraße. Summer was not too far away, and they would soon be back together. They were used to such separations and had spent as many years apart as together since their marriage. Graz looked like a way to bring that to an end, and Else returned to Hamburg full of hope for the future. Professor Wegener went to his rented rooms, spread his papers on his desk, lit a cigar, and began to write.
18
The Professor
GRAZ, 1924–1928
[Wegener] reached his conclusions principally by instinctive, inner intuition and never, or very rarely, through a formal deduction from a formula, although he was certainly able to do that as well with great ease. I was often amazed at the reliability of his judgment, especially when he considered physical questions that lay far outside his particular area of expertise. He used to say, after a rather long pause lost in thought, “Yes, I think that’s the case” [Ja, ich glaube, die Sache ist so], and most of the time it was so, even though it often took us many days afterward to find the evidence for it. He had an instinct for the truth that was rarely off the mark.
HANS BENNDORF (1931)
After Else departed for Hamburg, Wegener turned his mind to his lectures and waited for the final proofs of Klimate der geologischen Vorzeit to arrive. He still had the notebook in which he had recorded material for the book, and after he and Köppen had sent off the manuscript, he cr
oss-hatched in blue pencil page 152 of that notebook and wrote (also in blue) on the next page “Notizen für die 4 Aufl d Entstehung d Kontinente u Ozeane.” The blue pencil, in place of his normal graphite penciling, suggests that he was correcting proof at the time, which would put this in the late winter or early spring of 1924. While he (clearly) had planned a fourth edition immediately after the third—just as he had begun work on the third, even before the second was complete—Wegener would begin to collect data in this new division of the notebook only in the spring of 1927.1
In April 1924 he was poised once again between his career as an atmospheric physicist and his career as a theorist of continental displacements. Even the title of his professorship seemed to reflect this duality: “Meteorology and Geophysics.” He was also, for the first time in almost a decade, in a pleasant and relaxed state of mind; except for a brief period of convalescent leave in 1915 and a few cold months in the winter of 1919, it had been nearly ten years since he had been able to work on his own science without administrative responsibilities and without supervising other men. Since 1914 he had been a combat infantry officer, an adjutant, an instructor in aerial navigation for zeppelin pilots, the head of a Field Weather Service outpost, the head of the Domestic Weather Service (Hauptwetterwart für Heimat), and then head of the Field Weather Service for the Balkans.
After demobilization in the winter of 1919, he had enjoyed a few cold, intense, solitary months in Marburg, during which he had done fundamental work on lunar craters, the first original experimental/observational research since his traverse of Greenland in 1912–1913. This short sabbatical had been swallowed immediately, in April 1919, by five years of burdensome administrative and supervisory work at the German Marine Observatory. Almost all of the research and writing on continental displacements and the climates of the past he had accomplished in his “spare time” on evenings and weekends, on a schedule so grueling he swore that it was going to kill him.
Alfred Wegener Page 92
