Alfred Wegener

by Mott T. Greene

  Wegener’s first course with Bauschinger was “Celestial Mechanics: Older Theories.” He had missed “Introduction to Celestial Mechanics” (summer 1900), and there was almost nothing else he was equipped to take. He did sign up for another year of geographical position finding and celestial navigation with Marcuse, and this looked to be valuable. It consisted of both demonstrations and exercises, and Marcuse had designed the exercises specifically to simulate the kinds of problems one would be likely to run into on a scientific expedition. After selecting this course, Wegener ran out of reasonable choices in astronomy. Förster was teaching a popular course on the history of astronomy and a course on the mathematical reduction of astronomical measurements; the first was too elementary for Wegener, and the second too advanced. Bauschinger was also teaching a course in chronology and one on the construction and use of planetary tables, but both were too specialized for someone with—so far—only a summer-semester introduction to general astronomy.

  Bauschinger’s “Older Theories” course began with Johannes Kepler (1571–1630), who made the first determination of the laws of planetary motion, and Isaac Newton (1642–1727), who had spent much effort on determination of cometary orbits. It then passed through the elaboration of celestial mechanics by Pierre Simon de Laplace (1749–1827), Joseph Louis Lagrange (1736–1813), and Wilhelm Olbers (1758–1840) and finished with the methods of Karl Friedrich Gauss (1777–1855). In all, it covered the period from 1600 to about 1850. This approach allowed Bauschinger to develop the course as a history of orbital calculation and error reduction. He was in the midst of writing what would become the standard text on orbital determinations, Die Bahnbestimmung der Himmelskörper (1906), and was also spending much time documenting the history of the field in Germany and producing translations of hard-to-find earlier works, especially those of Johann Heinrich Lambert (1728–1777) and Johann Franz Enke (1791–1865).22

  Bauschinger was a prodigiously active observer and generator of planetary tables and ephemerides and of mathematical tables for the use of astronomical calculators. His most famous work, coauthored with Jean Peters (1869–1941) and regularly reprinted, was Logarithmic-Trigonometrical Tables to Eight Decimal Places, Containing the Logarithms of All Numbers from 1 to 200000 and the Logarithms of the Trigonometrical Functions for Every Sexagesimal Second of the Quadrant (1911).23 The number of decimal places in the tables was a signal of the lengths to which it was necessary to go when questing for accuracy in orbital determinations; the late date of its last reprinting (1970) indicates also that with Bauschinger’s work the quest had nearly reached its practical limit.

  The fundamental problem in this branch of celestial mechanics was to find the orbit (and thus the position relative to Earth at any given time) of an object such as a comet or an asteroid that was moving around the Sun, and to find it with a minimum number of observations—usually three. Restricting observations to the absolute minimum also minimized the immense amount of trigonometric calculation required to solve the equations involved in the problem. One took the celestial latitude and longitude (actually the right ascension and declination) of a celestial object on three successive occasions and, using these coordinates and the time of observation, generated a total of nine equations that had to be solved for nine unknowns.

  There were three principal approaches to the problem, all treated in Bauschinger’s course: Wegener was obliged to learn the theory and the methods and to perform the calculations in a variety of ways. Each approach had strengths and weaknesses, depending on the character of the orbit being studied, especially its eccentricity and the number and character of perturbations. Multiple methods were required of students, as one may observe in a sample problem of the period: “Take three observations of an asteroid not separated from one another by more than 15 days, or three of a comet not separated from one another by more than 6 days, and compute the elements of the orbit by both the method of Laplace, and also that of Gauss.”24

  As the academic year progressed, it seemed to fall into two quite distinct parts. The mathematics, physics, and celestial mechanics courses were mutually reinforcing and had considerable overlap, and they also shared the sense of mature, finished endeavors, nearly complete before Alfred had arrived in them. Their historical orientation, reaching back hundreds of years, seemed to include in its roster of predecessors nearly every great name in physical science. The other part of the year’s program, however, felt much less finished. If there was nothing new in the contents of Marcuse’s navigation and position-finding course, it had at least the sense of the possibility of novelty and adventure in its deliberate assumption that the skills being learned were for the use of explorers on expeditions. Alfred was gaining an instrumental technique that might help him find something really new—somewhere. On this same side of the line, the unfinished side, also came his final course enrollment for that year: Bezold’s course in general meteorology.

  Wilhelm von Bezold (1837–1907) was near the end of his career but still very active. He was the first professor of meteorology in Germany, the head of the Prussian Meteorological Institute, president of the German Physical Society, and past president of the German Meteorological Society. He had worked with Helmholtz and Planck and was a pioneer, along with Heinrich Hertz (1857–1894), in the study of the dynamics and thermodynamics of the atmosphere. He was an international leader in the establishment of meteorological station networks and of the exchange by telegraph of information about pressure, temperature, and wind observations. He was a leader in creating and interpreting daily weather charts as a basis for forecasting. He had a prominent place in every meteorological success of the past twenty-five years. Yet the story he told of his science was not at all like the triumphal narratives of the physics and astronomy classes. It was the story of something that was just coming into being. For this newborn science Bezold was a crusader, a recruiter, and a prophet. For all the tremendous attention paid to the atmosphere in the second half of the nineteenth century, he argued, all the major questions remained unanswered. What drives storms—what is their energetic, their thermodynamic foundation? How do centers of high and low atmospheric pressure interact? How do clouds form, why are there different kinds of clouds and cloud shapes, and why does it rain and snow and hail? Are there rhythms and cycles longer than the seasonal year? Where do tornadoes and waterspouts come from? The questions went on and on.

  Meteorology as presented by Bezold was about not weather forecasting but the struggle to create a physics of the atmosphere. One of the strongest claims to public (and government) attention for this new field was the role of manned flight in attaining the necessary data for atmospheric physics. Bezold was president of the Verein der Berliner Luftschiffahrt (Berlin Aeronautical Society) and was an enthusiastic promoter of manned ballooning for scientific purposes.25 Working together with Richard Aßmann (1845–1918) and Arthur Berson (1859–1942), Bezold had requested a grant from the kaiser of 25,000 marks in 1892 to support manned flights from Berlin; the young kaiser, enthused by the project, gave him 50,000 marks instead. Most of these flights were eventually made by Berson between 1892 and 1898 using Aßmann’s instruments.26

  With few exceptions, meteorology in the previous fifty years had tried to study the three-dimensional structure of the atmosphere using only two-dimensional methods of observation. There was, by 1900, a globe-girdling network of meteorological stations in the Northern Hemisphere, but the information it gathered was information about what was happening at the surface of Earth or at best a few meters above it. It had been possible to expand this network vertically by building and manning meteorological mountain stations, as advocated by the Austrian meteorologist and climatologist Julius Hann (1839–1921), who had an observatory on the peak of Sonnblick (3,106 meters [10,190 feet]) in Southern Austria, but few observers had as much success as Hann in adapting the results obtained to the understanding of storm systems. Manned balloon flights would and did allow the investigation of the three-dimensional structu
re of the atmosphere up to very great heights in the free air—away from the topographical and thermal effects of mountains. Bezold was certain that this information would allow the theoretical unification of meteorology as a physics of the ocean of air—all that was required was for young men of vision and courage to step forward and carry the program out.

  Wegener was yet in no position, and also under no pressure, to make any decisive move toward meteorology. He belonged at Berlin to a varied group of students who made their university home in the Akademisch-Astronomischen Verein (Academic Astronomical Society). The A2 V, as it was known, was one of the “black” scientific associations, in contrast to the “color-bearing” fraternities of the sort Wegener had joined in Heidelberg. It was affiliated with the Mathematics Society, though it was much smaller. The members were so close that, as Wegener’s friend Walther Lietzmann later remembered, it seemed more like a real fraternity than a scientific club. The members of A2 V were well-enough known for their liberal hospitality and gregariousness that members of the Mathematics Society often used to attend their evening lectures and social hours. Lietzmann recalled, tongue in cheek perhaps, that Wegener already exhibited an inclination toward polar matters—he was always willing to oblige the group with a lusty rendition of “Von dem Eskimann und von der Eskifrau.”

  Alfred was finding his way, acquiring friends and peers, but there is little doubt that this Berlin life was making him restless and that he was once again feeling constrained. At Christmas, he and Kurt hatched a plan: they would take the 1901 summer semester together at the University of Innsbruck, in Austria. They would register for field geology and botany and go exploring. When the term ended in April, they were packed and ready to go immediately. That summer there would be no hiking at die Hütte; they were headed for the Alps.

  Innsbruck

  Innsbruck is the capital of the province of Tirol, in southern Austria close to the Italian border. It sits in the middle of the wide plain of the River Inn at an altitude of about 600 meters (1,969 feet) and is completely surrounded by high mountains that seem to come right up to the edge of the town. In 1900 it had a population of about 28,000 and a university student body of just over 1,000. The mountains that surround Innsbruck are part of the central chain of the Eastern Alps, a 400-kilometer (249-mile) series of peaks from the Swiss border to the outskirts of Vienna. These mountains, largely of crystalline rock and covered with snow, ice, and some large glaciers, include more than fifty peaks above 3,048 meters (10,000 feet) and are the cradle of European alpine mountaineering.

  Innsbruck, Austria, where Alfred and Kurt Wegener studied botany and field geology in the summer semester of 1901, and where they learned Alpine mountaineering and climbed extensively. From a contemporary postcard in the author’s collection.

  Kurt and Alfred arrived in Innsbruck and registered for the summer term. Their program had a strong sense of purpose and place: it was not just in Innsbruck and the Alps, but about them, and it was a liberal cross between a university term and a summer scientific field camp. They registered for “General Botany” (lecture) and “Exercises in Identification of Flowering Plants, with Special Attention to Medicinal Plants” (lab), both taught by Emil Heinricher (1856–1934), an authority on wild iris and primroses growing at altitude. His lecture and laboratory were preludes to his course “Botanical Excursions,” in which students learned field identification and collecting of common and rare alpine wildflowers.27 Alfred and Kurt also registered for “Geological Tour of the Tirolean Alps” with Josef Blaas (1851–1930), who had spent his entire life hiking, exploring, and mapping the Alps and had just sent to press his seven-volume Geological Guide to the Tirolean and Vorarlberg Alps (1902).28 The microscale of geology was handled by Alois Cathrein (1853–1936), a specialist in crystal symmetry who taught an introduction to mineralogy, followed by a mineralogical field course: “Mineralogical and Petrographic Excursions.”

  Alpine botany is a surprise even for those who have some experience in plant identification, as Kurt and Alfred both had. As a very rough rule of thumb, every 200 meters (656 feet) of elevation is equal to a degree of latitude when considering the environment of the flowering plants. That is, in the continental interiors, a plant found near sea level at a given latitude will, for each degree of latitude one moves south, appear 200 meters higher in the landscape (and thus in the same approximate temperature conditions). Innsbruck was located 600 kilometers (373 miles) south of Berlin, so the plants within Innsbruck and its immediate environs on the flood plain of the Inn still contained wild species familiar to Alfred from summers at die Hütte. But a hike of 300–400 meters (984–1,312 feet) in elevation brought plants with no counterparts in North Germany at all, and a further 600–700 meters (1,969–2,297 feet) brought a whole new flora, whose nearest relatives at sea level would be found in Bergen or Stockholm. At the tree line, 1,000 meters (3,281 feet) higher up, one attained a tundra environment similar to that at sea level at the Arctic Circle, found in lowland Europe only at the North Cape of Norway and Sweden.

  In the course of a day hike one might pass through a number of vegetation zones, often very sharply demarcated. In early spring to midsummer one actually walked through time as well, for spring moves up the hillsides slowly and steadily, with summer in the valley, late spring in the high pastures, and early spring above the passes, with the dwarf and miniature trees and plants rushing to flower in their short season of growth, and where a chill hangs in the air, even on the sunniest days, with the slightest flush of wind.

  Field geology in alpine terrain offered a similar range of contrasts with the lowlands of the North. To begin with, most of Prussia had no other geology than the glacial geology and geomorphology of unconsolidated tills, sands, and other glacial outwash, all of it recent. The only sizable rocks available for view were the large, erratic boulders carried south from Scandinavia with the great ice sheets. In Innsbruck, except for the alluvium of the valley floor, the alpine pastures, and the moraines of the living glaciers, this dirt was out of the way and the rocks available for inspection.

  Alfred and Kurt’s principal field guide, Josef Blaas, was an expert on the Brenner Pass region immediately to the south of Innsbruck, a place combining ease of access and amenities, with exposures of fresh rock created by blasting to widen the road on this major trade route to Italy. Because Blaas and his colleague Alois Cathrein worked in crystalline (metamorphic) rocks as opposed to sediments, the field trips did not stop when the strata were overtopped. Even into the 1920s many classical geological field trips involving the traverse of a mountain chain would stop instruction for the day when the crystalline rocks near the crest were reached. The students would hike up over the summit ridge and descend, to begin the “geology” again the next day when the sedimentary rocks resumed.29

  Swiss, Austrian, and French geologists in the preceding twenty-five years (1875–1900) had made sensational discoveries in the Western Alps of massive folds and overthrusts (nappes in French, Decken in German) on scales of tens and hundreds of kilometers. These were structures so huge and so physically improbable (how could rocks maintain coherence thrust over such distances?) that most geologists disbelieved the published field reports and had to be convinced, as it were, on pilgrimage—literally taken to the top of the mountain to undergo conversion. Whereas all the excitement in European geology even a decade before had been in glacial geology, by the turn of the century the hottest topic was Alpine tectonics—the folding and thrusting of these huge mountain ranges. For introductory geology students to be introduced to dynamical and global theorizing was not as common 100 years ago as it is today, but in the Alps it was inescapable—there was almost nothing else to talk about. The Eastern Alps were puzzling, complex, contradictory, and still to be unraveled. Even if Alfred and Kurt could not grasp all the implications, there was a sense here of something new happening on a large scale, of major new interpretations, of great discoveries.

  In between the field trips, Alfred and Kurt went
hiking, scrambling, and climbing on their own. They arrived in Innsbruck severely underequipped and had to buy a complete mountain kit.30 Out of their quite modest allowances they procured the necessaries. First, they bought climbing boots with soles 15 millimeters (0.6 inches) thick (for rigidity) nailed with “triple-hobs.” Hobnailed boots provide traction on rock and are ancestral to the Vibram sole found today on almost all hiking and climbing boots. Because hobnails cannot find good purchase on hard snow and ice, Alfred and Kurt also each acquired crampons—sets of spikes that can be strapped underneath the boots. To this equipment they added ice axes and climbing rope. The ice axes they used are what today would be called “Alpenstocks,” staves of hardwood about the size and length of a broom handle, shod at the bottom with an iron spike and capped by a cast metal head with a pick at one end and an adze at the other. It was a multipurpose tool: it provided stability when hiking with a heavy pack, it served as a probe for crevasses, its adze blade could be used to cut steps, and the pick could be dug into the ice to arrest a fall.

  They started climbing during the Whitsun (Pfingsten) vacation, which in 1901 came in the last week of May, so on their first “Alpine tour” they encountered glaciers still deeply covered with snow. The planned sequence in which they explored the region indicates they had either good advice or immense good luck.31

  Climbing in the Austrian Alps in those early days before mountaineering became a popular sport was a wild and isolated pursuit, even if this sort of Tirolean trekking was not technically difficult by modern standards. Alfred and Kurt were on a series of expeditions and explorations, since they often followed trails and climbing routes that were scantily marked or not marked at all. They had their footgear and ropes and ice axes, but no climbing aids—no pitons, anchor bolts, ice screws, chocks, or wedges. They had access to few of the fixed cables and ladders available on these routes today, nor had they hard hats to protect them from falling rock and ice, nor slings and harnesses or any other of the wonderful devices modern alpinists enjoy.32 In return, they got the solitude, the sense of being alone, the wonderful (surely false but wonderful) feeling that perhaps no one had ever stepped here before, and the joy of self-reliance, of their own pace, of unscheduled progress, and of simple living.