Alfred Wegener

by Mott T. Greene

  By the following week he had recovered enough to finish the page proofs of his Greenland manuscript (working from his bed) and to send them on to Copenhagen, but he was still extremely weak. He wrote to Professor Richarz asking whether his formal inaugural lecture scheduled for 20 April might be postponed a week, as his doctor had urged him. This was good advice: it was the pattern with this particular influenza (like that of 1899 and even more so in the Spanish Influenza of 1918) that victims would feel better, return to work, and then relapse and die suddenly—a pattern noted by a number of Berlin physicians in 1909.

  Professor Richarz obligingly postponed the lecture until 7 May, which was fortunate for Wegener, because recovery was slow.53 By the end of April he was able to make the long-postponed trip to Copenhagen to help see his complex manuscript to the press.54 The pace was depressingly slow, and even this trip did not solve all the difficulties in formatting the tables and graphs.55 Spending the first few days of May packing his belongings for shipment to Marburg, he traveled there on 6 May and the next day delivered his lecture. It was the easiest of subjects for him, his history of astronomy from the pre-Socratics to the present, and, like his demonstration lecture in March, it was shaped to appeal to a broad audience.

  Here it was, then—the transition from scientific laborer to university instructor, the path so strenuously advocated by his father. Wegener’s appointment was official on 8 May, but there were no duties in the offing until October, when the Michaelis semester (winter semester, from October to April) would begin. He unrolled his polar bear rug in his study at Rosestrasse 9 and, with the coughing from his flu nearly abated and smoking cigar after cigar, set again to work.

  His illness and convalescence in March and April had put a crimp in his ability to write and smoke, but not in his ability to think, and since the lecture on 8 March, he had been increasingly drawn to the problem he had proposed in that lecture as the prime question in atmospheric physics: the causes of the major fundamental layers of the atmosphere. Their existence was not in question, but there was no physical explanation: what caused these inversions and discontinuities? Was the “upper inversion” (tropopause) really a unique layer in its prominence and solidity, or were there others? Was the “upper inversion,” in fact, really a permanent feature of atmospheric structure?

  Thoughts on the Tropopause

  This last question, the permanence and stability of the upper inversion (tropopause), had occurred to him while working in January on his paper “Layering of the Atmosphere.” Then, in March, he had noted in his Marburg lecture that the altitude of the upper inversion shifted with latitude: it was high in the equatorial regions and lower near the poles. This suggested that there was a link between the altitude of the tropopause and the prevailing average temperature at the surface. If this were so, he asked himself, would there not be a marked seasonal effect? Should it not be higher in summer and lower in winter, especially in temperate latitudes?

  The immediate spur to continue this work came to him in the June issue of Meteorologische Zeitschrift, containing two papers summarizing the work of August Schmauß (1877–1954) and Teisserenc de Bort on the “upper inversion.” These papers were electrifying for Wegener: “the first really excellent overview of the striking law-like behavior of this phenomenon.” Even so, Wegener continued, “I find missing here, as well as in all other similar work I have seen on this theme, an assessment of the simple fact that the temperature on the underside of the ‘upper inversion’ or, following Teisserenc de Bort, on the boundary surface between the troposphere and stratosphere, is lower in direct proportion to the altitude at which this surface lies.”56

  Wegener was looking here at data that (for him) were not only law conformable but begging to be expressed in law-like form. The relationship between temperature and altitude for the location of the tropopause had led Schmauß to postulate three mean “central temperatures” for the upper inversion, at their different altitudes (low, middle, high), leading to three empirically generated state curves for the atmosphere expressing the decline in temperature with altitude. “However,” Wegener plunged on, “the law I have just articulated [the greater the altitude the lower the boundary temperature of the tropopause] finds expression in the three mean ‘initial temperatures’ [given by Schmauß], but to my knowledge the investigation of this initial temperature as a direct function of the altitude, has never been carried out by Schmauß or anyone else who has studied the problem until now, and yet it seems to me that this statistical methodology is quite suitable as a means to produce law-like behavior.”57

  Wegener’s attitude expressed here is as interesting as it is characteristic of him. It is not so much his impatience (though that is there) as an astonishment that such well-respected researchers could produce such exciting and trustworthy work and then fail to make the “obvious” connections, connections (to him) as plain as day, leading directly to explanatory hypotheses and even to scientific laws.

  The paper that Wegener wrote in June 1909 on the upper inversion is almost a template for what would become his standard method of attack in all his theoretical work. It goes something like this: “I have just read something. It immediately occurred to me that such and such a relation followed from the ideas presented—but I cannot find any hint of this relation stated here.” Then a quick search of the relevant literature shows him that no one has produced such a relation. Then follows a speculative foray using whatever fragmentary data he can get his hands on. He develops a hypothetical relation and tests it using the data he has found. His hypothesis does not come from these supplementary data, but as an intuition based on the initial reading of the inspirational article or articles by others. He then works through the available data and finds, in spite of the sparseness and the fragmentary and provisional character of such studies as exist, that the relationship hypothesized has a clear signature in the data. A working scientist would today describe the sort of relationship Wegener thinks he has found as “robust,” a major structural fact of the world, insensitive to detailed departures from the central tendencies of the data. Wegener then proposes his relation be accepted provisionally and urges others to produce supporting studies, giving a clear formulation of what sort of measurements would provide confirming or disconfirming instances.

  He would think, write, and speak in this specific manner for the rest of his career. This method of work and of attacking problems had its roots in his training in astronomy in Berlin, where he had been taught to calculate cometary orbits from no more than three observations; it also expressed his own speculative and sometimes reckless cast of mind. It was, at this time in his career, certainly also an artifact of his playing “catch-up” with the major advances in aerology while he had been gone. Finally, it was also an expression of ambition (always with him) to discover something really important. In atmospheric physics as in Arctic travel, his chosen role and his great love were exploration, reconnaissance, and the mapping of new territory.

  Wegener’s analysis of the seasonal alteration in the height of the tropopause. While the data here are from Munich, the dashed line separating the circles and plus signs (different temperature regimes) is from the Lindenberg data. The point is that the line that separated the Lindenberg data also neatly divides the Munich data. See discussion in the text. From Alfred Wegener, “Über eine eigentümliche Gesetzmässigkeit der oberen Inversion,” Beiträge zur Physik der freien Atmosphäre 3 (1910): 206.

  If we now return, in light of this imaginative strategy, to the contents of the paper he wrote in June 1909 on the upper inversion, the following elements fall into place both logically and rhetorically. The material “just read” is the three-level temperature scheme in the paper by Schmauß. The “missing conclusion” is the determination of the precise relationship of temperature and altitude with the location of the lower surface of the inversion layer (the tropopause). The “fragmentary data” at hand are reports of pilot balloon ascents from Berlin and Lindenberg.

&
nbsp; Wegener’s approach also consisted of three parts: First he graphed the data, plotting altitude versus temperature in a scatter plot. Wegener then analyzed his plot by drawing a line at 45° as the mean line of the data points, passing through −50°C (−58°F), at 10,000 meters (32,808 feet) (or very nearly) dividing the data points into two groups. He used the standard value for the lapse of temperature with altitude (0.5°C per 100 meters) established by Hann in 1903. The data points then fell into a band 3,600 meters (11,811 feet) wide, across a span of temperatures of about 18°C (64°F). The altitude of the tropopause could (thus) vary by about 3.5 kilometers (2.2 miles) and (thus) exhibit a temperature variation of 18°C.

  Here it becomes interesting. Wegener contingently, and not quite arbitrarily, divided the data in another way. Beginning again with the Lindenberg results, he identified winter ascents with a small circle and summer ascents with a small cross. He knew, from reading Schmauß and Teisserenc de Bort, that the height of the tropopause was measurably different in winter and summer. He defined winter as an Earth surface temperature on average below +9.0°C (48.2°F), and summer as an Earth surface temperature above +8.9°C (48.0°F).

  He then generated the temperature at the altitude of the tropopause as follows: T = −50° − (h − 10,000) × 0.005 ± 9°C. That is, the temperature at the tropopause will be −50°C, minus the variation in the altitude from 10,000 meters, times a coefficient for the lapse rate, ± 9°C—the latter representing the width of the strip of tropopause temperatures clustered around the mean line at 10,000 meters.

  With the data set thus divided, one saw the frequency maximum for tropopause altitudes in the summer above the mean line and its maximum altitude in winter below the mean line. These maxima were there in the Lindenberg data, but not enough to support the argument by themselves. To strengthen the argument, Wegener took the Munich data and, rather than plotting a mean line of the data for Munich, used the mean line of the data for Lindenberg (10,000 meters, −50°C) superimposed on the Munich data. Here the result was striking: almost all the winter points are below the mean and the summer points above it. Once again, the zone of variation in altitude is approximately 3,600 meters wide, and there are clear frequency maxima for the summer and winter altitudes as well. Finally, once again using the Lindenberg mean across a chart of scanty data for three other stations at latitudes 38°, 45°, and 51° north, he established that the data points also lie within a 3,600-meter-wide stripe.

  Wegener concluded that in spite of the fragmentary data, there is a clear signature: records from six aerological stations show that “it seems accordingly, that this broad stripe is produced by an annual parallel displacement (Parallelverschiebung) of the mean line [of the altitude of the tropopause].”58 Wegener was buoyed in his conclusion by the knowledge that the data sets available for his inspection were accidental, and he had no choice among them as they were the only data that existed: “the results of this purely accidental compilation in which there was no choice, seems to me to be interesting enough to publish in spite of its intrinsic uncertainty.”59

  Then to complete the “template,” he noted that confirmation of his relationship would await further studies at the pole and at the equator concentrating on both the spread of temperature and altitude and trying to determine whether his formula would apply to the whole globe and not only to the middle latitudes. He concluded, “Unfortunately I have not been able to examine the values which Herr Berson has recently obtained in equatorial Africa. It would have been very interesting to see whether they would have fit (or not) the schematic pattern set out here.”60

  The presentation, then, is that of an open-minded but percipient observer who has used up all the available data in establishing a hypothetical relationship that he urges be treated as hypothetical until further studies can confirm it. This sort of formulation ends every speculative paper he ever wrote, and there are a great number of them. The remark about Berson’s refusal to show him the data reveals that Wegener was still smarting from their dispute. Quite coincidentally, an explanation of Berson’s refusal was unexpectedly forthcoming just as he had sent his paper off to Aßmann for publication, on 18 July 1909.

  An Unexpected Offer

  On 20 July Wegener received a long and astonishing reply from Aßmann. Aßmann had found the paper, on an initial reading, extremely interesting: “so far as I can see in a quick overview of [your paper] no one has ever before carried out an analogous study concerning the upper inversion.”61 Wegener’s astonishment stemmed not from this comment but from what followed: Aßmann was actually writing to offer Wegener Berson’s job at Lindenberg!

  “Since October or November,” wrote Aßmann, “Berson has been in the grip of a rapidly worsening neurasthenia, and I am in great need of finding his successor, for which I must, by all means have a theoretician, because the current theoretician, Coym, does not have the capacity to reach a sufficient level of care and exactitude.”62 Arthur Coym, who had joined the staff at Lindenberg during Wegener’s short tenure there, was the person who Wegener had come to believe stood in the way of his obtaining permanent employment at a higher level than a mere technical assistant. Now it appeared that his work had been found unsatisfactory, and with Berson’s illness, the door was once again open at Lindenberg for him.

  “Neurasthenia,” Berson’s complaint, is a diagnosis (no longer generally in use) for a variety of symptoms that in the nineteenth century were thought to be a disorder of the nervous system. But when a man like Berson returns from equatorial Africa and begins to manifest fever, lassitude, aches and pains, and inability to concentrate, it is easy to imagine that he had contracted one of the chronic diseases of the tropics, most likely malaria. In any case, Berson, who would yet live another thirty years, was incapacitated and imminently taking a disability leave or retirement; the job was now open and waiting.

  Aßmann made a persuasive case, running through the other likely candidates and rejecting them one by one: this one wanted too much money, that one is a social democrat, another is not enough of a theoretician. “I know it will not be easy for me to persuade you, my dear Dr. Wegener, but I believe that you are the right man for me and the right man for the job.”63

  If Wegener were to return to Lindenberg, Aßmann would raise the salary from 2,700 to 3,200 marks. “Of course as my first assistant, you would no longer have to work the [kite] winch, and, aside from some unavoidable administrative duties, you would be free to pursue your purely scientific work without interruption.” Moreover, Aßmann continued, “you can see that this is an opportunity that will not likely occur again … obviously other [meteorological] stations—first at Danzig—will one day be established, and the post of Director-Superintendent would open up—and Danzig has a Technical University!”64 Aßmann was as much as offering him the directorship of the new station at Danzig when it opened, if he would take the job of Observator at Lindenberg now.

  It was a stunning and completely unexpected offer that, if accepted, would throw Wegener into an entirely different life and career track. Most of the other young meteorologists (including Kurt) were in technical universities or at observing stations, not at regular university posts. The job was clearly a way up into official rank in government service, rather than university life.

  The day after receiving this letter, Wegener left for Göttingen to give a lecture at the Aeronautical Club there, his head spinning. The morning after the lecture (23 July) he wrote to his parents and asked for their advice. He told them he had asked Aßmann for time to think and would ask Köppen, his brother Kurt, Richarz, and others about their assessment of future prospects and positions before deciding.65

  Yet he had no sooner returned to Marburg than it seemed clear to him that this was not the path he wished to follow. His parents’ reply has not survived, but we know how strongly Richard Wegener had championed university positions over government ones and “real” universities over the technical institutes. On 27 July Wegener wrote to Aßmann thanking him for the
opportunity but urging instead that Aßmann pursue Friedrich Bidlingsmaier (1875–1914), a geophysicist and specialist in geomagnetism who had aided Wegener in 1906 to prepare himself for Greenland.66 Bidlingsmaier was a docent in Berlin and had shown some interest in coming to Lindenberg, but he was reluctant to give up his Berlin appointment. Moreover, he had been called up for a term of naval service. Wegener pointed out to Aßmann that he himself had been called up and would be on maneuvers with his regiment from August until late September.67

  Aßmann persisted, however, and again appealed to Wegener to take the job. Wegener wrote to him on 18 August from the military barracks at Charlottenburg, profusely thanking him, and asking him to specify the conditions for his entry into the employ of the observatory at Lindenberg once more. Wegener could see, he thought, that a year or so hence when the Greenland results were published, his position would be quite different, and that the conditions of employment would have to be extremely favorable to overcome his reservations.68 He was in a quandary, not knowing which way to go, and asked for yet more time to consider. At this juncture both men appear to have decided to let the matter rest for a time.

  At the end of September, following his military course at Charlottenburg, Wegener visited his parents and Tony briefly at die Hütte before returning to Marburg. Much of his attention was taken up with ballooning. His experience as a balloonist was one of the main reasons that Richarz had wanted him at Marburg. Richarz had access to a balloon free of metal in its rigging which could fly cross-country trailing a magnetometer and produce profiles of Earth’s magnetic field. Marburg was becoming in 1909 (and continues today to be) a center for civil aviation, both scientific and recreational, and had just established its first airfield and aerodrome.