Skip to main content
Select Source:

Penck, Albrecht

PENCK, ALBRECHT

(b. Reuditz [near Leipzig], Germany, 25 September 1858; d. Prague, Czechoslovakia, 7 March 1945)

geomorphology, geology, paleoclimatology, hydrology, cartography.

Born near the outer limit of the maximum southward advance of the Quaternary Scandinavian ice sheet, Penck took a lifelong interest in glacial deposits. In 1875 he entered the University of Leipzig to study natural sciences. In the same year Otto Torell delivered a forceful lecture at Berlin, which persuaded his audience that the boulder clay of the north European plain had been carried by a continental ice sheet and not by floating ice; he thus vindicated and perpetuated the ideas of A. Bernhardi (1832). Shortly thereafter Penck found and wrote about a northern “basalt” erratic embedded in the diluvium near Leipzig.

At Leipzig, Penck studied chemistry under Adolf Kolbe, geology under Hermann Credner, mineralogy and petrography under Ferdinand Zirkel, and botany under August Schcnk. In I877 Credner chose him to assist in a geological survey of Saxony, and Penck mapped on a scale of 1:25,000 the Grimma-Colditz area southeast of Leipzig. In 1879, from the detailed analysis of a sequence of glacial sedimentation (Geschiebeformation) that showed alternations of unbedded glacial clay (Geschiebelehm) and laminated sands and clays, he postulated at least three main ice advances, or glacial phases, interspersed with two interglacial periods during which rivers had laid down normal, bedded deposits. In the following year Penck worked under the geologist Karl von Zittel at Munich, which was near the outer (northern) limit of the maximum advance of the Alpine ice sheets. Penck’s subsequent investigations into Quaternary geology were especially concerned with Alpine glaciation.

In 1882 Penck summarized his local fieldwork in Die Vergletscherung der deutschen Alpen... which soon became a standard reference and was his Habilitationsschrift as Privatdozent in geography at the University of Munich (1883). Two years later Penck was elected to the chair of physical geography at the University of Vienna, where he stayed for nearly twenty years, developing a well-equipped geographical institute and achieving an international reputation. When not lecturing or writing, he collaborated with Eduard Brückner on extensive field studies in the Alpine valleys undertaken with a view to perfecting a chronology of ice sheet advances and retreats. The immediate result was a series of articles on the influence of glaciers on valley development and valley forms; the ultimate result was the classic three-volume Die Alpen im Eiszeitalter (1901–1909). During this period Penck traveled to England several times from 1883, to the Pyrenees (1884), and to Norway (1892) to study glacial features and other landform types for a general work on morphology. Reflected in numerous articles dealing with erosion and denudation, these travels culminated in his two-volume Morphologie der Erdoberfläche (1894). Penck subsequently made several journeys through Western Europe and visited Canada and the United States in 1898, the Balkans and Australia in 1900, and the United States and Mexico in 1904. Before leaving Vienna, he had taught many German and foreign scholars.

In 1906 Penck succeeded Ferdinand von Richthofen in the chair of geography at the Geographisches Institut of the University of Berlin. His inaugural lecture dealt with the fundamental importance of fieldwork in geographical studies (“Beobachtung als Grundlage der Geographie”), and as director of the institute for the next twenty years he set a fine example. In the winter of 1908–1909 he and his family visited the United States. Penck taught at Columbia University and lectured at Yale and other universities; he also met G. K. Gilbert in California. They returned to Germany via Hawaii, Japan, North China, and Siberia. (In the same scholar exchange program, W. M. Davis lectured on landforms at Berlin). The last part of Die Alpen im Eiszeitalter appeared in 1909; up to this time, and for a few more years, his work at Berlin was virtually an extension of his studies at Vienna.

The outbreak of World War I was a turning point in Penck’s thought rather than in his life. Apart from Quaternary problems, which had always interested him, his thinking became more geographical and less geomorphological. Directing more effort to sociopolitical themes, he showed an increasing interest in ethnographic, cultural, and nationalistic topics. In 1917–1918 he served as rector of the University of Berlin; and his inaugural discourse, “Über politische Grenzen”, was a study of frontiers, especially European. The best frontiers, he thought, coincided with the living space (Lebensraum) indispenable to the life and security of a state. Germany had in part acquired Lebansram but unfortunately had failed to retain the entire mineral basin of Lorraine. Now in 1917 Penck hoped that Germany would keep all the territories currently occupied so far as they were indispensable, and that it would further acquire colonies to furnish essential raw materials.

These and similar views led his friend Davis to write in a review of the Festband (1918) that was presented to Penck by his former students on his sixtieth birthday: “He used to be liked as much as admired but during the war some of his statements have lessened the esteem formerly felt for him” (Geographical Review, 10 [1920], 249). Penck played a considerable role in the revival of German nationalism after World War I; he was, for example, one of the chief advocates of the foundation of the Berlin Volkshochschule. The Lebensraum concepts (Reichboden, Sprachboden, Volksboden, and Kulturboden)and the ethnographic, cultural, and social surveys fostered and undertaken by Penck and others later proved disastrous but were then highly popular in Germany and had honored antecedents in the work of Friedrich Ratzel. Penck thus enjoyed great national esteem and achieved membership in the Berlin Mittwochsgesellschaft. His success was dimmed when his brilliant son Walther died of cancer in September 1923 at the age of 35. He supervised the publication (1924–1928) of his son’s literary remains, including four articles, and Die morphologische Analyse (Stuttgart, 1924), an important contribution to the study of landforms.

About this time Penck’s interests in oceanography yielded their best results. As director of the Institut für Meereskunde he was responsible for extending the oceanographic museum at the University of Berlin and was involved in the arrangements for the Meteor Expedition (1925), which, under A. Merz, made several sounding traverses in the South Atlantic. In 1926 Penck retired from the chair of geography at Berlin and was succeeded by his former student Norbert Krebs. Penck continued to live in Berlin, however, where he worked on geographical and editorial problems in connection with the geographical institute of the university.

By 1927 much of the wartime breach of friendship with Davis had been healed—largely owing to the death of Walther Penck, whom Davis greatly admired—and Penck spent some time lecturing in the United States, with the University of Arizona as his base. In 1928 he presided with distinction over both the centennial celebrations of the Berlin Gesellschaft für Erdkunde and the meetings of the Oceanic Conference. Most of his biographers consider 1928 “the peak of his career,” but from a scientific viewpoint there can be no doubt that he reached his peak in 1909 or 1910. His Austrian work was full of scientific innovations and included his concepts for an international map on the scale of 1:1,000,000; his Berlin work was full of the less scientific branches of geography. In fact, for the last thirty years of his life he was more a regional geographer and demographer than an earth scientist.

The majority of Penck’s approximately sixty-five articles and books written after his retirement concern Quaternary chronology, cartography, and population problems. There remained withal more than a hint of Lebensraum—evident in his description in 1934 of Krebs’s important atlas Deutsches Lebensraum in Mitteleuropa, which Penck had intiated, and in his associated interest in political boundaries—as well as a tinge of regional geography (Länderkunde). Penck also wrote several competent biographies, including those of Brüuckner (1928), Gilbert (1929), J. Partsch (1928), Richthofen (1930, 1933), and F. von Wieser (1929). His last projects involved the study, with a group of students, of the relationship between the potential productivity and possible number of inhabitants per unit area of land mass. During World War II, his house was damaged by bombs and he moved to Prague.

The assessment of Penck’s contributions to the earth sciences is complicated by the change in his views. He did not hesitate to accept new theories or to recant his ideas. This development can be illustrated clearly from three facets of his work. First, in his concepts of regional geography he was an early follower of Richthofen. Thus, his “Das deutsche Reich” (1887) superimposed spatial distribution of various phenomena upon a detailed physical base, with the use of new physiographic terms such as Alpenvorland (foreland). But after 1914 his regional concepts changed rapidly to unit areas of landscape in which the visible repercussion of the naturla and sociocultural environment allowed the establishment of core and fringe areas. Man’sd activities and his acquired traits and inherited characteristics entered more strongly into the spatial relationships. The concept of Lebensram loomed large with what might be considered a regrettable chauvinistic veneer, and with strong hints at possible expansion and regrets at the noncoincidence of pollitical social economis and culture distrbutions. Second, Penck changed his views considerably on the descriptive analysis of landforms. At first his elaborate empirical descriptions lacked any notable sequential development among the individual forms; but under teh infulence of Davis, Penck recognized the value of a “cycile” or sequential progress. After 1918, he rejected Davis’ theory and, with his son Walther, he placed the rate and nature of uplift as dominant factors in the analysis of certain landforms. Third, Penck quite early agreed with Suess on the leading principl that secular variations in the relative altitude of land and sea were due to worldwide fluctuations of sea level (eustasism) rather than to crustal movements. By 1900 Penck had modified his views and had accepted independent crustal movement (regional or local) as a concomitant factor in elevating or depressing coastlines.

Assessing his contribution is complicated also by the wide range of geographical topics that he discussed. He published more than 400 books and articles, and many of the latter were issued separately in book form. Yet his chief scientific writings concerned four branches of the natural sciences: Quarternary geology and chronology gemorphology hydrology, and cartography.

In his Quarternary studies Penck’s early work on the superficial deposits of the north German lowlands and of the Alpine valleys and piedmont plains increased the number of distinct epochs fo glaciation to three or four. Prior to Penck’s work only two such epochs were commonly accepted in continental Europe. Although James Geikie had enumerated five ice advances and James Croll (on climates theories) had enumerated seven, Penck’s suggestions were the first to be based on firm geological evidence. Following the publication fo Die Alpan in Eiszeitalter the sedimentation evidence for at least four main ice advances in the Alps was indisputable They were named Günz, Mindel, Riss, and Würm the first three being right bank alpine tributaries of the Danube and the last a tributary of the Isar River near Munich. Penck used for refrences the capital letters in a wide spaced alphabetical sequence, which could, if necessary, incorporate future discoveries of ice advances in a mnemonic oder.

For nearly half a century this scheme provided a nomenclature and a time scale for European Pleistocene studies. Die Alpen in Eiszeitalter was a milestone in the history of the investigation of teh Quaternary; its results, according to Davis (Geographical Journal, 34 , [1909], 651), formed “an indispensable guide for all future progress must be measured.” The findings revealed the great length of the Riss Wurm interglacial and its mildness as compared with the present, as shown by the plant bearing Hotting breccia near Innsbruck. The Wurm (or last ice advances) had, on moraine evidence, experienced at last three significant pauses or stages of retreat. During glaciation, the permanent snowline of the Alps had advanced 1,200 meters; and its lowering was caused, Penck and Bruckner believed by a moderate decrease in the mean annual temperature and consequent increase in proportion of snow fall to total precipitation, rather than by an increase in the total precipitation.

Penck lived to see significant modification to his scheme: an older (Donau) advance was subsequently added, which allowed the scheme to conform to postulated variations in insolation: varies local terminologies not based on the Alps were adopted for Scandinavian and British ice advances; and the main glaciations, particularly the Wurm, were more rigorously divided into stadials and interstadials Among Penck’s other contribution ot glacial geology was the term “tillite” whcih he conied in 1906 for the ancident Dwyka moraines of the Permo caarboniferous glacitions in South Africa.

Penck’s main contributions in geomorphology were to the general classification of landforms to knowledge of individual landform types and to the signification of climatic change in landforms analysis Morphologie der Erdoberfläche the first unified test of geomorpholoy followed inn the tradition of Suess’s Das Antlitz der Erde (1883–1909) and Richthofen’s Führer für Forschungsresisende (1886) Penck acknowleged his dept to each and also to James Dana. Penck work is divided into three parts The first part deals mathematically—with the aid of numberous formulas and equations—with general surface morphology and with Penck work concets of morphography. The swecond part describes in detail the various forms (landforms that are recognizable upon the various process endogenous and exogenus at works in their genesis. Most of the principles stated here were basically familiar to students but much of the information was new adn the presention was unified ingenious and scientific. The thrids inculde teh study of occeans coastline and island The arrangement of particular sections in his work is similar to Ricthofen Forschungsreisende but he battalion of faces evidence and computations more closely resembles Dnaa’s geological manuals. As Carles Lapworth admiringly (Geolographical journal5 , [1895], 580) “the work is an encyclopaedia fo face and conclusion admirably classified adn digested and affords at the same time a complete index ot the literature of the subject.”

Penck’s attempt to construct a unified system of landforms analysis and classification was of out standing importance. he emphasized form ro shape in relation ot genetic process rather than to function process and he state that fundaemntal types could be formed by many different processes This Penckian system creasted nurtured the German as dirtinct form the American (Davisian), sysytem of landform analysis Penck’s system was expounded more widely in 1885 at the Sixth International Geographical Congress in London with a masterly summary in English It stated that changes on the earth’s surface results from erosion (ture eriosion and denudation), accumulation and dislocation whcih cause the foramtion of new surface and the destruction and altreation of existing surface. Thus the character of the surface relief depends parthly on the geological structure may be of a startified nature “(particalloy horizotal, undulation or warped, intensely folded fractured) or of an igneous nature (extrusive or volcanic adn intrusive)Erosien dendation and accumulation affect these geological structural types and results in the creation of six fundamental forms the plain the escarpemt the valleys the mount the cup shaped hollow and the cavan. The forms are differenctiated by their slopes; and the forms eleemnts combine to build up funfametal forms which usaully occru in association ro groups ot compose a special landscape The formel ements fundamental forms and landscape. The forms elements fundamental forms and landscape are the three minor morphological elements of the earth’s surface. The three higher categories are the extends area fo eqaual elevation (a combination of landscape)the systems ( a grouping of such areas) and finally the continental block and agencies of changes there is one realtions hip teh amjor forms are due excluivrely to dislocations while the minor forms arsien in a varieyt of ways.

The same fundametal from can from either erosion accumulation or dislocation and with six fundamental forms Penck suggested the term “homogeetic” for thpose with the same orgin But a uniform and clear terminology he believed sa well sa a knowledge of the gensis of alndforms superior to that existing already had to be acquired Penck state that each fundamental forms (except the plain) inculde three group of homogenetic features and that each group falls into various subdivision sccording to the special knid of erosien accumulation or dislocation that has operated By naming the homogenetic members of each fundamental from according to its genesis relation (plain of accumulation). The definition could be amde more explicit by the addition mof adjective (plain of amrine accumulartion).

One of the most significant features of geomorphology is the contrast between this system of ladmnfroms description and the cycle concept of Davis who postulated a sequence of development in each landscape and based landforms analysis mainly on structure process and stage Penck recognized and used some of Davis sequentila ideas; but as Walther Penck from 1912 on, became intrigued with the intense folding of the Alps he and his farther increasingly emphasized the important fo rate of upolift on valleys-side slopes.

In 1919 Penck published in important article on the summit levels of the Apls “Die Gipfelflur der Aplen” In direct opposition ot FDavis theory that peaks were eroded uplifted peneplains Penck development the concept that emchical disintegration rapidly increasing with altitude and thatn in each region there exists a maxmuim altitutde above whcih the highest relif will not rise explained the existence of amture or flattened surface at great heights in the intreior ranges of the Alps by assuming that the massif was uplifted slowly at first and then more rapidly The spaecing of the valleys dissection and the natural of the valleys side slopes reflection this accelerating uplif. At an intermediate stage the sharp ridge creats (where the steep valleys side slopes interest)will mainin a contant, aboslute altitude and constant relief ebcause the rate of upheaval and rate of deeping of the master valleys are balanced Davis replied at length in “The Cycle of Erosion and the Summit Level of the Apls” (Journal of Geology, 31 [1923], 1–14). Althought he admitted Penck’s exceptional stature as a geographer and a “unquestionably large” value of the “Gipfelfur” essay he considered in necessary to “correct Penck’s so-called correction of the Davis cycle concept adn by 1928 he had already abandoned the idea of the sequential development of landfroms in favor of a schems based on the ratio between rates of erosien and uplift (“Die Geographie under den erdkundlien Wissenschften” in Naturwissenschaften16 [1928], 33–41)

Penck’s chief contribution to knowledge of individual landforms types were to glacial forms especially in Die Alpn im Eiszeitalter, In this work as well as in eariler article he stressed the importance of the overdeepeing of glacial valleys. he was also instrumental in poining out the general association between till sheets terminal moraines and outwash gravles and sand thet develop on bording lowland outside the overdeepeing piedmont baisn at the end of an Alpine valleys This association was later equally applied to the peripheries of contineral ice sheets.

To climate geomorphology as distant from paleoclimateology Penck ande tow significant conttribution. He recognized and aeral classification of surface morphology bade on correlation with humid subhmid semiaried ariod and nival (glacial climate areas he was one of the first ot insist that “we see on the earth’s surface not only the feature of the present cliamte but also those fo a past climate” (American Journal fo Science, 19 [1905], 169)

“Die Donau” (1891), the Oder River (1899) were among the earilst scienctific analysis of the water budget and the flow regime of CentralEuropean rivers His interest in cateogrpahy was responsible for initating amny distribution amps and at least one influential atlas on socioculutral themes, Krebs’s Deutsches Loebensreum in mitteleuropa. He Advocated the production of Prussian amps on the scale of 1;1,000,000, for general purpose and of a standards series of goble maps on a scale of 1;1,000,000, Penck introduced this idea in 1981 at the Fifth International Goegraphical Congress in Brene. The matter was raised at each successive congress; and at the eight congress in Washington(1904), Penck again address the delegates and presented maps complied on that scale by the French German andn British International conferences were subsequently held in 1908 and 1913 to resolve outstanding problems with regard to standard specifications spelling and production of the 1;1,000,000, world sheets (IMW). Of the estimated 840 sheets needed to cover the alnd areas of the worlds only 97had been published by 1931. Within a few years of Penck death the greater part of the land areas had been covered by standard IMW maps

BIBLIOGRAPHY

I. Original Works. Penck’s published works comprise about 410books and articles. The selective list given here include works referred to in the texst and other taht exemplif his contribution to major themes. His works on Peistocene geology inculde Die Vergletscherung der deutschen Alpan. . . (Leipzig, 1882); Die Aplan im Eiszeitarltar, 3 vols, (Leipzig 1901–1909), written with E. Britckner; and “European im Eiszeitaler” in Geographische Zeitchrif43 (1937) pt. 1, On geomorphology see Morphologie der Erdoberflach 2vols (Suttgart 1894); “Die Gemorphologie als genetische Wissenschalft” in Report of the Sixth International Geographical Congress London 1895(1896), 735–757; and “Die Gipfeflur der Alpen,” in Sitzungsberichet der Preussischen Akademie der Wissenschaften17 (1919), 265–263. On hydrogaphy see “Die Donau,” in Schriften des vreeins zur Verbreiturng naturwissensschaftlicher Kenntnisse in Wien, 31 (1819) 1–101; and “Der Oderstrom,” in Geographische Zeitschrift5 (1899), 19–47; 84–94; and on cartography “The Cobnstruction of a Map of thje World on a Scale of 1;1,000,000,” in Geographical Journal1 (1893) 253–261.

Other works on geography include “Das deutsche Reich,” in A Kirchhoff’s Landerkunde vou Europa I (Leipizg (1887) 115–596; “Die osterreichische Alpan grenze” in Zeitschrift der Geselleschaft fur Erdkunde zu Berlin (1915); 329–368, 417–448; Uber politische Grenzen (Berlin 1917) “Die Starke der Verbreitung des Menschen” in Mitteilungen der Geographischen Gesellschaft in Wien(1924), 241–269; Beobachtung als Grundlage der Georaphie (Berlin 1906) and “Geography Among the Earth Sciences” in Proceesings of the American philosophical Society66 (1927), 621–644.

II. Secondary Literature. The chief biographies and bibliographies of Penck arte; 1877–1903; Drucksriften vou Albrecht Penck (Vienna, a list of 162items compiled by A. E. Forster Erich Wunderlin, “Albrect Penck Zu seinem 70 Geburtstage am 25 septemper 1928” in Geographischer Anzeiger, 29 (1928) 297–306; 1’877–1928 Druckschriften uou Albrecht Penck. . . (Berlin 1928) with bibliography of 350 items ot early 1928 Nobert Krebes, “Nachurf auf Albrech Penck” in Jahrbuch der Deutxhen Akademie der Wissenschaften zu Berlin (1946–1949), 202–212; Johann Solch “Albrecht Penck” inMitteilungen der Geographischen Gecellschalft in Wine,89 (1946) Heft 7–12, 88–122 Walter Behrmann “Albrecht Penck” in Quartar (1951); 190–139; Edgar Lehmann “Albrecht Penck” in Deutsche Akademie der Wissenschalft zu Berlin64 (1959) Herbert Louis “Albrect Penck und sein Einfluss auf Geographie und Eiszeitforschung” in Die Erde98 (9158) Heft 3–4, 161–182(extends bibliography of 1928 Druckschriften to a total of 406items) and G. Engleman “Bibliographies Albrech Penck” in Wissenschaftliche Veroff d. Deutschen Insite fur Landerkunde (1960) 331–447; For Penck’s contributions to cartography see Walter Behrman “Die Bedeutung Albrecht Pencks für die Kartographie” in Blätter d. Dt. Kartogr. Ges., no.2 (1938) 22pp.

Robert P. Beckinsale

Cite this article
Pick a style below, and copy the text for your bibliography.

  • MLA
  • Chicago
  • APA

"Penck, Albrecht." Complete Dictionary of Scientific Biography. . Encyclopedia.com. 23 Aug. 2017 <http://www.encyclopedia.com>.

"Penck, Albrecht." Complete Dictionary of Scientific Biography. . Encyclopedia.com. (August 23, 2017). http://www.encyclopedia.com/science/dictionaries-thesauruses-pictures-and-press-releases/penck-albrecht-0

"Penck, Albrecht." Complete Dictionary of Scientific Biography. . Retrieved August 23, 2017 from Encyclopedia.com: http://www.encyclopedia.com/science/dictionaries-thesauruses-pictures-and-press-releases/penck-albrecht-0

Penck, Albrecht

Albrecht Penck (äl´brĕkht pĕngk), 1858–1945, German geographer and geologist. He was professor at the Univ. of Vienna (1885–1906) and at the Univ. of Berlin (1906–26) and was director (1906–22) of the institutes of oceanography and of geography, Berlin. He is noted for his study of glaciation (especially in the Alps), for his pioneer classification of land forms, and for his work in the development of modern regional geography. Outstanding among his many works is Morphologie der Erdoberfläche [morphology of the earth's surface] (1894, rev. ed. 1928).

Cite this article
Pick a style below, and copy the text for your bibliography.

  • MLA
  • Chicago
  • APA

"Penck, Albrecht." The Columbia Encyclopedia, 6th ed.. . Encyclopedia.com. 23 Aug. 2017 <http://www.encyclopedia.com>.

"Penck, Albrecht." The Columbia Encyclopedia, 6th ed.. . Encyclopedia.com. (August 23, 2017). http://www.encyclopedia.com/reference/encyclopedias-almanacs-transcripts-and-maps/penck-albrecht

"Penck, Albrecht." The Columbia Encyclopedia, 6th ed.. . Retrieved August 23, 2017 from Encyclopedia.com: http://www.encyclopedia.com/reference/encyclopedias-almanacs-transcripts-and-maps/penck-albrecht

Penck, Albrecht

Penck, Albrecht (1858–1945) A German mineralogist from the University of Berlin, Penck's main interest was in Quaternary glacial land-forms, which he classified according to shape. Some of his work was done in co-operation with his son Walther Penck.

Cite this article
Pick a style below, and copy the text for your bibliography.

  • MLA
  • Chicago
  • APA

"Penck, Albrecht." A Dictionary of Earth Sciences. . Encyclopedia.com. 23 Aug. 2017 <http://www.encyclopedia.com>.

"Penck, Albrecht." A Dictionary of Earth Sciences. . Encyclopedia.com. (August 23, 2017). http://www.encyclopedia.com/science/dictionaries-thesauruses-pictures-and-press-releases/penck-albrecht

"Penck, Albrecht." A Dictionary of Earth Sciences. . Retrieved August 23, 2017 from Encyclopedia.com: http://www.encyclopedia.com/science/dictionaries-thesauruses-pictures-and-press-releases/penck-albrecht

Penck, Walther

Penck, Walther (1888–1923) A German geologist, Penck assisted his father Albrecht Penck in his studies of land-forms. Independently, he worked on the structure of mountain regions, especially the Alps, modifying Suess's ideas on continental uplift.

Cite this article
Pick a style below, and copy the text for your bibliography.

  • MLA
  • Chicago
  • APA

"Penck, Walther." A Dictionary of Earth Sciences. . Encyclopedia.com. 23 Aug. 2017 <http://www.encyclopedia.com>.

"Penck, Walther." A Dictionary of Earth Sciences. . Encyclopedia.com. (August 23, 2017). http://www.encyclopedia.com/science/dictionaries-thesauruses-pictures-and-press-releases/penck-walther

"Penck, Walther." A Dictionary of Earth Sciences. . Retrieved August 23, 2017 from Encyclopedia.com: http://www.encyclopedia.com/science/dictionaries-thesauruses-pictures-and-press-releases/penck-walther