Alfred Wegener

by Mott T. Greene

  Next at the podium was Albrecht Penck, and he was condescending and intransigent. As we all know (he began), almost all the evidence we see is of vertical movement. As for this business about continental and ocean crust being different, he did not think it established. It could just be that the continental crust that covers the ocean floor has been cooled by ocean water and shrunk down, thus producing these gravity readings.51 He did not believe that the continents could plow through the Sima and at the same time be upthrust and folded on their leading edge. This was just intuitively impossible for him to imagine. From his perspective, the second edition of Wegener’s book did not solve the problems left by the first edition.

  He liked Diener’s solution to the problem of getting animals and plants across the North Atlantic by island arcs, and he said that Wegener’s hypothesis did not rule this out.52 As for coastline similarity, that did not mean a former connection, and maybe there were mountain ranges transverse across the floor of the Atlantic which we just hadn’t found yet.53 The continental shelf is not a vertical wall but a stepwise descent, so coastline matching at the edge of the continental shelf doesn’t really mean anything more than coastline matching at sea level.54

  He then went on to question the accuracy of the longitude measurements of Koch. Here he moved not in vague generality, as above, but in effective detail, pointing out that Wegener’s account of what Koch had said and what Koch had himself said were different, that the uncertainties were gigantic, and that what Koch had proposed as a possibility Wegener had transformed into a revolutionary certainty that did not exist. Penck was on excellent ground here and scored heavily against Wegener, given Wegener’s challenge that proof of displacement was a final test his hypothesis had already passed.55

  However, Penck still had to deal with the problem of the Southern Hemisphere, and here he quickly went from a definitive demolition of Wegener’s measurement claims to vague arm waving against the reassembly of the southern continents. This is, he said, “beset with many difficulties,” and “our knowledge of the details is sketchy,” and “we have to be cautious.”56 Wegener’s idea of the horizontal motion of continents is a plausible explanation for a range of quite various and differentiated data, he admitted, and this makes it extremely “seductive,” but there is more evidence for sinking than for splitting and drifting. He concluded by raising an entirely different issue and saying that no matter how much evidence one collects in favor of a hypothesis like this, no matter how seductive it is and how well it functions, one really cannot accept it until we know the mechanism.57

  Penck sat down, and it was time for Schweydar to discuss the geophysical implications of Wegener’s hypothesis. His remarks did not seem to start well for Wegener, because he began by pointing out that Wegener’s hypothesis depended crucially not just on isostasy but on a particular interpretation of gravity differences associated with the British astronomer George Airy, whereby gravity deficits and excesses are removed by assuming that mountains (and in Wegener’s case continents) have deep “roots” of light material. He then went on to say that he had looked into this question rather deeply in his own research and had become convinced that the approach taken by Wegener to the interpretation of the gravity data was the right one.58

  After this brief scare for Wegener, everything else in Schweydar’s remarks was smooth sailing. Geodesy supports Wegener’s idea of floating continents, Schweydar said, and our knowledge of the strength of materials makes it plausible that they could plow through the Sima. Whether there could be currents in the Sima is another and more difficult matter to establish, but even that cannot be ruled out. As for Penck’s claim that the lack of accurate measurement data for the motion of continents counts against Wegener—that Koch or others did not establish this motion—this was not, said Schweydar, the case. The measurements do not count for him, but neither do the lack of same count against him.59

  Schweydar went on to say that the idea of a pole-fleeing force, or at least the tendency for continental masses on a fluid Earth to move from the poles toward the equator, was perfectly well established, and given that Earth does behave as a fluid on appropriate timescales, both the continents and the poles might move. Not only that, said Schweydar, but “in any case it must be taken as likely that the continents, under the influence of a pole fleeing force, suffer displacement towards the equator.”60 Schweydar was uneasy about the linkage of the pole-fleeing force to the westward motion of the continents, and he wondered about the size of forces generated in the movement toward the equator and the velocity of the continents. Finally, he expressed doubts about the ability of the displacement of continents, even large continents moving through several tens of degrees of latitude, to force the pole of Earth more than 2°–3° away from its current position. This, however, was a matter for investigation.61

  When Schweydar concluded, Wegener was offered, as was customary in such symposia, a final word, and he did not conceal his satisfaction with the outcome for his theory. “Anyone,” he began, “who has followed the geological literature on continental displacements from the first heated review by Semper, to the remarks before you by Koßmat, cannot help but see a slow but continuous transformation from complete rejection, to at least partial consent. Such an accommodation I see especially in Koßmat’s unreserved affirmation of the necessity of accepting large horizontal displacement of portions of Earth’s crust as well as large displacements of the pole. The remaining differences, I believe, we can now eliminate.”62

  He spoke first to Koßmat’s arguments and made a respectable claim: that geological opinions contrary to Koßmat’s assertions existed in most cases, and particularly that with regard to the connection between the Appalachians and the mountains in Europe Koßmat was swimming upstream against the preponderant geological opinion. What remained was a mild difference of opinion on specific geological facts, and Wegener ended by saying that he thought he had been able to answer most of the objections and did not doubt that Koßmat and his colleagues would come in the course of time to agree that this was the case.63

  Penck came in for much rougher treatment. He would not, said Wegener, even touch Penck’s notion that he can make a free choice between the geophysical data and his alternative explanation for the difference between the continental and the ocean crust. Similarly, Wegener said, he found himself unable to make any sense of Penck’s notion that the statement “land bridges, or permanence of oceans, it is just one assertion against another” is somehow a point against my hypothesis: “That was exactly my point!”64 The displacement hypothesis is what allows us to move beyond these dueling assertions, “as anyone would know who had read the first chapter of my book.”65 When, Wegener continued, Penck cites only negative opinions about former connections across the Atlantic, he could easily give the impression that this represents some sort of geological consensus, but this isn’t so. And when he cites Diener’s work, on which his rejection of such links depends, he has had to resort to assertions that a simple review of the literature would show have already been stamped as “grotesque misunderstanding” and thoroughly refuted.66 Wegener went on in this tone and in this vein, pounding Penck on point after point for about twenty minutes, and one is left with the impression of Penck as a senior scholar who thought he could get away with a casual dismissal, instead of a serious argument, and who paid a heavy price.

  Wegener’s response to Schweydar was but a single paragraph. Wegener said that he was looking forward to Schweydar’s future publications on the topic, that he had found Schweydar’s comments on the pole-fleeing force extremely interesting, but that nothing he had said had surprised him, as he had never yet met a geophysicist who opposed the possibility of displacements. Wegener ended with a general thanks to the group for all the objections brought against the displacement theory, as the only way forward to clarify and improve it. He made a single reservation: “However, I think that any unprejudiced observer will be able to reconcile any of the facts brought forward by Penck wit
h my presentation of the displacement theory.”67

  One can imagine that Wegener would have been excited and even elated by this outcome. Schweydar, as the representative of geophysics, had supported him in every single assertion in the displacement hypothesis, though urging some revisions in Wegener’s characterization of the action of the pole-fleeing force. Schweydar had stated that he intended to work on the problem himself, thus underlining Wegener’s contention that a community of investigators was already using the displacement hypothesis as a way to guide their research. Moreover, Wegener had been able to represent Koßmat’s remarks not as a thoroughgoing critique of the displacement hypothesis but as a major step forward in the willingness of geologists to accept both large lateral displacements of the continental crust and large displacements of the pole as absolutely necessary in order to explain the data at hand. Finally, he had come up just short of accusing Penck of intellectual dishonesty in representing his own opinion as the consensus of the field and in using an already-discredited publication by Diener to support his claims.

  There was something larger at stake than this “victory” over Penck. Winning some war of words with a critic was something that Wegener cared little about, and had he not been goaded by Penck’s attitude in the symposium, he might never have responded as he did. Much more important to him was the realization that the status of his ideas about continental displacement was now really as he had described it: a working hypothesis guiding an identifiable and growing community of investigators from a number of different disciplines.

  Yet a victory it was. Otto Baschin (1865–1933), a geographer and meteorologist who had been to Greenland with Drygalski, attended the session and wrote a glowing summary of it for Die Naturwissenschaften, which appeared in early April. He said that Wegener’s presentation had been brilliant and that the large audience was swept away with enthusiasm for the idea and for the astonishing number of facts that Wegener was able to bring together. Wegener’s critics, he concluded, had not been able to marshal one single secure fact to challenge the central premises of the theory of continental displacements.68

  It is a major step forward when a hypothesis becomes severed from the name of its proposer and takes on a life of its own. So it was now with Wegener, with his displacement theory launched into the world, and with a community of investigators moving this hypothesis where it would go, not because he told them to, but because that is what happened to the hypothesis as they wrote and published scientific work. He could help inform the community, he could continue to contribute on his own, and his work would always be of prime importance to those attracted to working in terms of the idea, but he was not any longer in charge.

  Still, in the mind of the public and the scientific establishment, in the spring of 1921 this was “Wegener’s theory.” Scarcely a week after Otto Baschin had previewed the proceedings of the Berlin symposium in Die Naturwissenschaften, the same magazine devoted an entire issue (other than news and book reviews) to an extensive review of Wegener’s hypothesis by Bruno Schulz (1888–1944), an oceanographer at the Deutsche Seewarte in Hamburg. It was less a review than a summary of the hypothesis, but Schulz concluded with the following judgment: “As we look at the elaborate structure of the displacement theory and its manifold connections, it is hard to avoid the impression that the theory possesses an inner core of truth, especially since no one has, as yet, been able to bring forward any convincing counter-evidence.”69

  When Wegener returned to Hamburg, buoyed by his Berlin reception, he could see that he needed to begin immediately on the new edition of the book. His strategy in Berlin of avoiding a mixture of hypothesis and fact in his presentation, as well as his decision to group the evidence in a series of modular categories emphasizing their independence from one another, had paid a huge intellectual and rhetorical dividend. He was stung—but convinced—by Penck’s remark that the second edition of his book had not solved the problems of the first edition. Wegener had rejected and overcome the specific criticisms that Penck had in mind, but he had to agree with the overall judgment. The strength of the hypothesis would not, in future, lie in a firm integration of every bit of evidence into a seamless whole, but in the production of a summary digest of what different investigative communities, not in direct touch with one another, were producing.

  Wegener had known even before the second edition was out that there would be a third edition, and he had already begun to make provision for it in 1920. In December of that year, Wegener had purchased a quadrille-ruled, clothbound notebook, about 13 centimeters × 19 centimeters (5 inches × 7 inches), and had written on the cover “Kontinental-Verschiebungen.” Beginning in late November 1920, he had begun to make notes and extracts from books and papers. This is the same process he had followed in preparing the second edition. Then, his materials had been organized in a different way, within the covers of the first edition rebound with interleaved blank sheets. He would not repeat this strategy this time with a copy of the second edition; perhaps money was tight, and perhaps he realized that he had tied the structure of the second edition too much to the critiques of the first. He was prepared now to move to a new structure for the book in its third incarnation, and thus the notes would find their home in the appropriate sections of the new edition of the book and would not need to be married to any specific portion of the second edition.70

  There was unexpected time and opportunity to move forward with research on continental displacements in spring 1921: Wegener returned to Hamburg to discover that his ambitious meteorological program had been effectively canceled by Germany’s growing budget crisis. The plans for the expansion of the kite and balloon station at Großborstel, long since approved by the ministry, had now been shelved for lack of money. Without the buildings, offices, and machine shops, there could be no large-scale experimentation with new instrument designs and no regular program to fly them.

  Wegener would still be able to carry out a modest but steady program investigating ways to improve meteorological instruments; with the promise of meteorological flights using fixed-wing aircraft, Wegener worked hard on the problem of finding ways to keep recording instruments, especially their clockwork, from freezing up: this was important both for polar meteorology and for atmospheric research.71

  Working with Eric Kuhlbrodt, he was trying to modify the design of theodolites for tracking balloons. This was a problem that dated from his days in Lindenberg and his very first solo publication there on a theodolite designed by Alfred de Quervain. Wegener’s seagoing trip in late 1909 and early 1910—to track upper-level winds across the South Atlantic—had failed to produce results for a number of reasons, but especially because the balloons he sent up were too small to be easily followed with a theodolite, and the controls adjusting this telescopic instrument were so fine that once a balloon was lost to view, it was very difficult to locate it again. Wegener and Kuhlbrodt wanted to find a mechanical way to allow very fine adjustments and very large adjustments of altitude on the same instrument.

  These plans notwithstanding, the budgetary news was still a catastrophe. Kurt and Alfred’s program to turn Hamburg into Germany’s new center for atmospheric research had ended, they realized, before it even began. Kurt had worked hard through 1920 to obtain surplus warplanes to convert to meteorological use, and these planes arrived in Hamburg in April 1921. However, by the time they arrived, Kurt had already decided to leave the observatory and move to Berlin, where there were more planes and, more importantly, the gasoline to fly them. Although the Hamburg aircraft did fly throughout 1921, there was only enough gasoline for two flights per month of about one hour duration each.72

  Alfred would also be able to continue a very limited program of aerology in the context of his university teaching, and he scheduled a course in that subject at the university for the Easter term 1921 (April–July).73 However, it appeared to him that his days of active data gathering in meteorology and atmospheric physics might be over, and that more and more he would be
a teacher and mentor to younger colleagues.

  At the observatory he was not a selfish or distant leader, nor did he misuse subordinates. Johannes Georgi, Wegener’s former student at Marburg and now his assistant at Hamburg, recalled,

  I observed how cautiously Wegener made use of his intellectual superiority. We were walking along the corridors of the Seewarte one day when Wegener talked about various experimental equipment, and also wanted to hear my suggestions. Although a meteorologist, I happened to have read about some hydrodynamic experiments with pulsating balls in water, which had been described in 1876 by the father of the famous meteorologist Wilhelm Bjerknes. Wegener listened with interest, and I was flattering myself that I had told him about something new when, without any unkind intent on his part, he showed in the course of conversation that I had not mentioned all the facts of the matter—in short that he knew far more about these old and rather off-track experiments than I did. That was not the only occasion during the course of the next ten years that I came away red in the face after conversations with him, shamed by his more extensive knowledge and at the same time by his kindheartedness.74

  In addition to this downsizing of his meteorological work, there were other decisions pending in spring 1921. He and Köppen had to sit down and decide how they were going to proceed together. Köppen’s paper “Migrations of the Pole, Displacements of the Continents, and the History of Climate,” prepared in January and February 1920, finally appeared a year later in the January/February and the March 1921 issues of Petermanns. The delay was frustrating but unavoidable; paper was still scarce, and the journal was much reduced in size, with each monthly number about one-third the size of its prewar counterpart. Köppen’s second paper, “Causes and Effect of Continental Displacements and Migrations of the Pole,” had been postponed again and again and was now scheduled to be published, also in two parts, in July/August and September 1921. This second paper, worked out with Wegener, and partly written by him, was a mathematical discussion of the pole-fleeing force, in which they had actually attempted a calculation of the size of the force. Using data from Krümmel’s Handbuch der Ozeanographie plotting the relative area of land and water on Earth’s surface for every 5° interval of latitude (in thousands of square kilometers), they tried to estimate the moment of inertia of the amount of continental mass at each latitude, but they found the calculation too hard.75 Indeed, Wegener had said in the second edition of his book that someone, someday would carry out the numerical integration, but not him, and not now.