Originally published as:
Torge, W. (2012): 150 Years of International Cooperation in Geodesy: Precursors and the Development of Baeyer’s Project to a Scientific Organisation. ‐ Zeitschrift für Geodäsie, Geoinformation und Landmanagement (zfv), 137, 3/2012
Fachbeitra Torge, 150 Years of International Cooperation in Geodesy ...
150 Years of International Cooperation · in Geode.sy: Precursors and the Development of Baeyer's Project to a Scientific Organisation*
Wolfgang Torge
Summary ternationaler Kooperation wird ausführlicher eingegangen, Geodesy commemorates th is year the founda tion of the abschließend wird auf die spätere Erweiterung zur globalen "Mitteleuropäisc he Gradmessung", which started its activi Wissenschaftsorganisation und die immer stärker werdende ties 150 years ago. Originated from an initiative of the Prus Einbindung in die interdisziplinäre Geoforschung hingewiesen. sian General Baeyer, this regional geodetic project required international cooperation. Outstanding organization soon led Keywords: Are measurements, Earth figure, Genera l Baeyer, to a scientific body which continuously extended over the International Association of Geodesy, Mitteleuropäische globe and fin ally built a global network of geodetic scien ce, Gradmessu ng represented today by the "Internationa l Association of Geo desy" (lAG). The following paper first remembers the start of international The Origin of Modern Geodesy and Early cooperation at the beginning of modern geodesy, as real International Cooperation : 18th Century ized through the arc measurements of the 18th and the early 19th century. First attempts for arc measu rements covering Geodesy, by definition, requires in te rn ational collabora cen tral Europe then are fou nd in the firsthalf of the 19th cen tion on a global scale. Thi s becomes clearly visib le with tury - connected with the names of Zach, Schumacher, Gauß, the beginning of modern geoclesy, wh ich may be reck Müffl ing, Bessel and Struve, among others. Ba sed upon a onecl from the 171h century. The heli ocentric world system memorandum presented 1861, Baeyer proposed a coordinat with the annual revolution of the Earth araund the Sun ed proceeding and clearly defined the problemstobe solved. and the daily rotation of the Earth ha cl been accepted at This idea soo n led to a governmen tal supported project and an that time, and physics ancl astronomy postulate an Earth orga nization wh ich rapidly extended beyond the boundaries fi gure flattenecl at the poles (Perrier 1939, Bi alas 1982). of central Europe. Th is early phase of international coopera The corresponding Earth mo clel is basecl on the theory of tion is di scussed in more detail. Finally, the later extension of hycl rostatic equilibrium (Newton** 1687, Huygens 1690), this early structure to a global scientific organization and the the observecl polar flattening of Jupiter (Jean-Dominique increasing incorporation into interdiscipl inary geoscientific Cassini 1666). ancl the latitucle-clepenclence of gravity research is shortly described. found by pendulum measurements (Richer 1672/73, Hal ley 1677/78). This is a great challenge for geoclesy: to Zusammenfassung prove the polar flattening by geometric methocls and to in diesem Jahr gedenkt die Geodäsie der Entstehung ihrer in cl etermine the parameters of such an Earth moclel! For ternationalen wissenschaftlichen Vereinigung vor 150 Jahren. a rotational elli psoid, these parameters woulcl be the Auf Initiative des preußischen Generals Baeyer entstand die semi-major axis and the geometric flatteni ng. The arc 11Mitteleuropäische Gradmessung((, ein zunächst räumlich be measurement methocl known since an tiqui ty is avail grenztes Projekt. Die hierzu notwendige internationale Zusam ab le for this purpose. Triangulation introcluced by Snel menarbeit wird effektiv organisiert und führt- bei laufender lius ( 1614/15) offers an efficient proceclure to determine Erweiterung der Aufgabenstellung - schließlich zur globalen geocletic (ell ipsoiclal) differences in length, wh ile the cle Vernetzung der geodä tischen Wissenschaft, heute repräsen• tennination of latitucle, longitucle and azim uth can be tiert durch die 11 /nternationa/ Association of Geodesy(( (lAG). basecl on well-known astronomical methods. A First at Der folgende Beitrag erinnert zunächst an die mit Beginn der tempt in this direction is carried out by J.-D. Cassini and modernen Geodäsie einsetzende länderübergreifende Zu his son Jacques carrying out a triangulation ( 1683 - 1718) sammenarbeit bei den Gradmessungen des 18. und des frü• along the meridian of Paris. Dividing this meridian arc of hen 19. Jahrhunderts. Erste Gradmessungen in Mitteleuropa a·2o' extension into a northern and a southern patt and oder Ansätze hierzu finden sich dann in der ersten Hälfte des 19. Jahrhunderts- verbunden u. a. mit den Namen Zach, * Modifizierte und ins Englische übersetzte Fassung eines Vor Schumacher. Gauß, Miiffling, Besse/ und Struve. Baeyers Idee trages im Ra hmen des Festkolloquiums ., 150 Jahre Mitteleuro eines koordinierten Vorgehens mit klarer Aufgabendefinition päische Gradmessung in Sachsen• am 1. Juni 20 12 in Dresden. führt schließlich - auf der Grundlage einer 1861 vorgelegten •• Names written in italics refer to historical persons, with rel Denkschrift - zu einer zwischenstaatlichen Zusammenarbeit, evant years of important publications or surveys, and not to Iist die bald über Europa hinausreicht. Auf diese frühe Phase in- of references.
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separate evaluation led to an Earth model elongated at 2 Central Europe at the Turn of the 19th Century: th e poles, with a negative· fl attening of - 1/95. Thi s result Military Triangulations and the Beginning of was in agreement with a few older arc measurements, Are Measurements bu t contradicted the hypothesis of an Earth ll attened at th e poles. The poli tical situation in centrat Europe is less favour This is the .beginning of the well -known dispute be able for large-scale triangulations of high standard. This tween the fo llowers of Newton (llattening at the poles) is due to the strong separation into local territorial units, and the Cassi nis (elongation at the poles) which is solved which is especially pronounced in Germany; for the his by the famous arc measuret1lents in Lapland (Maupertuis, tOty of geodesy in Germany we refer to Torge (2009). Cla irnut et al. 1736/37) .and in the Spanish Vice-Kingdom Among the remarkable exceptions are the triangul a of Peru - today Ecuador (La Co11dami11e, Bouguer, Godi 11 tions carried out in the dukedo m of Oldenbu rg (Georg et al. 1735- 1744), ini tiated and organized by the French Christiall vo 11 Oeder, 1781- 1785) and in th e princi pali ty, Academy of Sciences. The early co mbination of the Lap and later kingdom, of Saxony (Friedrich Ludwig Aster, land arc with the Pa ri ~ ri1eridian arc revised by Cassi 11 i 1780-18 11), both fo llowing the example of the geodetic de Thu1y and La Caille ( 1739/40) already yields a polar sutvey of Denmark ( 1762 - 1779) un der Thomas Bugg e. fl attening of 1/304. This is co nfirmed by th e combina An important intermedi ate phase occurs at the turn of the tio n of further arc measurements, although the ll atten ing 19'" ce ntu ry, with the extension of French influence over values vaty between 1/1 44 and 1/352. These grea t French centrat Europe through the Napoleonic wars. The military arc measurements not only require political agreements sutveys carried out by th e well -trained French engi neer between the countries in volved, but also are the begin geogra phers are based on triangulation, and shall extend ning of international participation at large-scale geodetic the French map of scale I : 86400 on the occup ied or al projects. The Lap land expedi tion, fo r instance, included lied countries. Triangul ation of the occupied German re the Swedish astronomer Celsius, and the Spanish navy gions left of the Rhine ( 1802- 1809) is connected with the officers Jorge Juan and A ntonio de Ulloa active ly co n name of Trc111c hot. The upper Rhine area is sutveyed by tributed to the measurements and the evalu ation of the He111y ( 1804), while Epailly performs a rapid triangul a Peruvian arc measurement. tion of Hannover ( 1805 - 1806), and Bo1111e establishes a The !arge differences found for th e tlattening (and nat first trigonometric network in the allied Bavaria ( 1801- ura lly also fo r the semi-major axis) of an Ea tt h ell ipsoid 1807). The Batavian Republic is triangulated by Krnye11 - led to first discussions on the figure of the Earth, starting l10jj ( 1802- 181 1) . All these triangulations are co nnected already in the 18'" century. ln the beginning it is tried to to the new arc measurement along the Pa ris mericlian keep the ellipsoidal Earth model, and to ex pl ain loca l and ( 1792 - 1798) carri ed out by Dela mbre and M echain in or later also large-scale deviati ons through the effects of der to defin e the metre as a natural unit of length, and topography, geology, and co ntinent-ocean distribution. thus refer to the geodeti c datum provid ed by the Paris Different strategies are proposed in order to solve this obsetvatoty. This is also va lid fo r the Prussian mi litary problem, including the red uction of loca l anomali es and triangulation of Westphalia ( 1795 - 1805) ca rried out un the introduction of a latitude- or longi tude-dependent der the direction of Colonel 110 11 Lecoq, in a period when tl attening parameter. Araund 1·800, the time is ri pe for Prussia had withd rawn from th e coalition against France. a new definition of the Ea rth fi gure, whi ch is introduced At the end of the Napoleo nic wa rs, Prussia reo rganized soo n after by Gauß, Besse/, ancl oth ers (see below). Th is its mapping organizations and concentrated them on th e coincides with national geodeti c surveys organizecl or General Staff(Torge 2002). Un de r the directi on ofGeneral sponso red by the respecti ve governments, followin g th e 110 11 Miijj7i11g, Traneiioi 's tri angul ati on of the Rh ineland cou ntty-wide triangul ation carriecl out fo r the "Carte de is continued since 1814, and continued th rough Hesse France" (Cass i11i de Thtuy, 1733-1750). We also recog and Thu ringia to Prussia's eastern provinces, reaching nize sign ifica nt improvements in the measurement tech ßerlin in 1820 and ßreslau in 1828, East Prussia fina lly niques, characterized by the bimetal baseline apparatus, is connected in 1832. Müffling had already participated the Borda repetition circl e, and the R(IIIISden second the in Lecoq's triangulation of no rth-western Germ any and odoli te. These technica l develop ments are accompanied the triangul ation ofThuringia, and he ea rly develops the by a remark able progress in th eo ry, as the transition idea of a longitude arc measurement between Dunkirk from the plane or spheri cal computation to the ell ipsoi (no tt hern -most baseline of the Paris meridian arc) and the dal one (Lege11dre, Lagra 11ge, Laplace, Gauß, and others), Seeberg baseline near Gotha (see below). Fo r this purpose and the introduction of the Ieast-squares method (Gauß, Müffling (being governor of Pa ris, which was occupied by Legendre). Another exa mp le fo r ea rly in ternational col allied troops) contacted Delambre in 1815, but the project laboration then is th e trigonometric con nection be tween failed for obvious reasons. the astronomic observatories in Paris and Gree nwich Here, we have to refer to the activity and th e innuence ( 1784- 1787), which also represe nts the beginning of the of the astronomer Franz Xa/Jer IJOn Zach, who - at the geodetic survey of Great ßritain und er the direction of the turn from the 18'" to the 19'" century - developed Go Ord nance Survey (Roy, M udge, Colby, Jam es). tha to a centre of scientific exchange in astronomy and
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geodesy (Brosche 200 I). Zach had been asked in 1802 by the king of Prussia to perform a triangulation ofTh uri ngia, and from thi s develops th e plan of an arc measurement in the centre of Germany, covering a difference of 4° in latitude and 6° in longitude, respectively. Among others, Fig. 1: Ga uß and Miiffling take part in the fo ll owing astronomic Carl Friedrich Gauß and geodetic Observations, and in the measurement of ' (1777-1855). the Seeberg baseline ( 1803 - 1805). With the revival of the Oi l-painting by Gottli eb war between Prussia and France, this first scientific geo Bi ermann (1887), after deti c enterprise in Gennany abruptly ends in 1806. Nev an original portrait by ertheless, Miiffling holds th e Seeberg baseline (which was Christian Albrecht Jensen. partly measured only) for suited to proviel e the scale of Copy Gö tting
3 First Half of the 19th Century: "... Der König hat mir die nötigen Fo nds lll einer Grad Are Measurements and New Definition of mess ung von Skagen bis Lauenbu rg ... bewilligt ... wäre the Earth Figure es nicht möglich, da ss Sie ... durch Ha1111 011er fort bis gegen Gotha, oder bis an die bayeriscll en Dreiecke The first half of the 19111 century is characterized by a führten ... ". refin ed defi ni tion of the Earth figure and by state geo detic swveys of hi gh quality, which are often also related Gauß immediately responds very positively: to the global problem. Thi s again requires international collabo ration, which is differently marked acco rding to ".. . Diese Gradmessung in den k. dänischen Staaten personal engagement, scientific networks, and poli tical wird uns ... über die Gestalt der Erde schöne Aufscllliis strategies. se geben. Ic/1 zweifle indessen gar nicht, dass es in Zu At the century 's beginning is the new state survey of kunft ZLI I/lachen sein wird, Illre Messungen durch das Bavari a ( 1808 - 1828), wh ich is outstanding in original Königreich Hanno ver südlich fortwsetzen ... ". ity and quality, and connected with the name of Jollann Georg 110 11 So /dn er. lt links up with the previous French ßy order of King George IV ( 1820), Gauß gets the permis work, but is distinguished significantly through the qual sion to co ntinue the Danish arc measurement through ity of the measurements (new survey instrumenlation de Hannover. Reconnaissa nce,. angle measurements and veloped by the Bavarian workshop of Reicllenbacll), the computations of the tri ~ n gul at i o n chain connecting the introducti on of the Soldner-coordinates, and the devel observatories Göttingen and Altona are carried out by opment of a complete theo ry of a geodetic survey. The Gauß himself, and it is this projec t where he inve nts Bavarian state survey is intended to serve as geometrical the heliotrope, and applies the method of Ieast-squares bas is forareal estate cadastre and for topographica lmap developed by him. From the very begin ning he co nsid ping, a strategy reaching fa r into Future! The ex pl oitati on ers the arc measurement (which later wi ll be extended
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to a triangul ation of the whole kingdom) as a part of a Future trigonometric network covering Europe. This be comes visible in a Ietter ( 182 1) directed to his scholar Gerfing (Professor in Marburg and si nce 182 1 Director of the trigonometric bureau, and as such responsible for the Fig . 3: trianguladon of the electorate of Hesse): Fried rich Wilhelm Bessel (1784-1846). Portrait by "... Es wäre gewiß äußerst wichtig, wen n der größte Christian Albrecht Jensen Teil IJO n Europa vo llstä ndig mit ein em Netz überzogen (1839) wäre, und nach und nach werden wir dahin komm en; http ://en. wi ki pedi a.org/wi ki/Fri ed rich_ j eder Staat sollt e es sielt zur Ehre rechnen, seinen An Wilhelm_Bmel teil daran so gut zu tiefem, da ss er würdig sei, neben den besten zu stellen" (Lehmann 1955). Russia suggests in 1829, to connect th e tri angulation Consequently, Gauß connects his arc measurement not in the Baltic provinces with the trigonometric chains of only to the Danish meridian· arc in the north, and - after the Prussian general staff, which meanwh ile had reached proper extension - to the Krayen/w.fftriangulation of th e West Prussia. Friedricll Willl eim Bessel (Fig. 3), Profes Netherlands, but also to the triangulation of Miiffling and sor at the University of Königsberg and director of the to the geodeti c survey of Hesse. He also thinks to include astronomic observatoty, strongly promotes the Russia n the triangul ati ons ca rried out by Bo l111 enberger in Wi.irt proposal and emphasizes the importa nce of such a con temberg and by Eck lwrdt in the grancl duchy of Hessen nection for global geodesy: Darmstadt into a Future European network. Gauß' inten tion obviously is the common acUustment of a central "... dureil die Vergleiclnwg der geodätischen Verbin European arc from Denmark to Italy, using th e original dung IJOn Königsberg und Dorpat, mit derjenigen wel data. Unfortunately, his endeavours to get the Observa che durch astronomische Beobachtungen gegeben tvor tions of Soldner from the Bavarian government Iead to den ist, ein neues Res ultat für die Figur der Erde zu a success only in 1827 - at that time Gauß had already erlangen ... ". given up his plan of a large-scale computalion (Groß mann 1955). By i.ncluding a baseline and astronomical Observations, the proposed pure trigonometric connection is widened to a proper arc measurement ( 183 1- 1836), with (now) Ma jor Baeyer participating as representative of the Prussian General Staff (H amel and Buschmann 1996). The coll abo ration between the ingenious astronomer Besse/ - his geo detic work has signif1 cantly promoted theory ancl practi ce Fig. 2: at the developing science of geodesy - and the geoclesist Wilhelm Struve (1793- Ba eyer, weil ex peri encecl in tri angulation, prove cl to be 1864). Portrait by Eduard cxtremely successful (Eggert 19 11). The high quality of Hau (1837) th is arc measurement set new Standards fo r geodeti c http://commons.wikimed ia.org/wiki/ ,.,,.,, , ,,., N, .:. ~ •-'•.w" , I File:Wilhelm_Struve._183 7.jpg work, and gave rise to a scicntillcally based renewal of !/. ~ the tri angul ati on in Prussia, with Ba eyer as responsibl e personage. The final report ( 1838) on the arc measure The Ru ssian-Sca ndinavian latitude arc measurement ment in East Prussia is ecl ited by Bessel and Ba eyer, and ( 1816 - 1852) along the 27" E meridian represe nts another aga in cl ea rly states the idea of a European contribution international geodetic enterprise ofthat tim e, with rele to the determination of the fi gure of the Ea rth: vance to the later project of Baeyer (e. g., Pettersen and Müller 2009, Lemke 2011). lt starts from two arcs inde "... eine Verbindung, welclle, indem sie auch die meis pendently established in the Baltic provinces of Russia, ten europäischen Stemwarten berührt und also, durch onc by the Co lonel (later General) Carl Tenner, and the die Vergleichung häufiger und über den größten Tlteil other one by Professor Friedriclt Georg Willt elm Struve tJon Europa vertlt eilten astronomisclten Beobachtun (Fig. 2), Di rector of the astronomic observatory in Ta rtu, gen, mit der beziehungsweisen Lage für die Bestim Estonia (then Dorpat). ln 1828 the two arcs were con mung der Figur der Erde, wenigsteiiS in dem Umfange nected and extended to the north ancl to the so uth, f1n ally dieses We/ttileils w erhalten, welche den darauf zu reaching a length of about 2800 km between the Arctic griindenden Scflliissen IJiel größeres Gewicht tJe rltiess, Ocea n ancl the Black Sea. In 2005, this arc with more als die abgesonderten Gradm essungen bisher haben ge than 30 still existing monuments has been incl uded in wä II ren können ... ". the UN ESCO worlcl heri tage Ii st.
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Parallel with these arc measurements, the discussion on le11. Die vorhandenen Messungeil 110 11 Meridianbögen the fi gure of the Earth - assumed to be a rotational el zeigen 11iimlich entsclriedene U11 regelmiißigkeiten des li pso id - co nti nues and finally converges to a refi ned Fortschreiteils der Polhöhen, welche ma11 als Folgen definiti on. This is ca used not only by the discrepancies kleiner Erhöhungen der Oberfläche der Erde iiber, oder between the results of different arc measurements, but ihrer Vertieju11gen wrter der Obe1jliiclre des zur Ve r also by a first evalu ation of globally distribu ted pendu gleich 1111g genommenen Rota I ionssphii roides ansehen lum measurements. Laplace, e. g., publishes fl attening mu ß ... ". values between 1/3 21 and 1/336 in the "Mechanique Ce les te" ( 1799), as derived from pendulum observations. The determinati on of the deviations of the geo id from Th e new defin iti on of the "mathematical" fi gure of the a reference ell ipso id thus has become the funda mental Earth then is especial ly connected with the names of problem of global geodesy. This is j ustifi ed all the more Ga uß and Bessel. as the elli psoids co mputed by Delambre ( 1810), Wal lJ eck ln a Ietter to Scl111macher ( 1823), Gauß, e. g., di scusses ( 18 19), Ai1y (1830), E11erest ( 1830), Bessel ( 184 1) and the defl ection of the verti cal of 5.5'' observed between others have proved to be a solid basis for the computa Göttingen and Alto na and states: ti on of national geodetic surveys (Straßer 1957).
"... so beweiset dies nur, dass im Kleinen die Erde gar kein Ellipsoid ist, so ndern gleichsam wellenförmig 11o n dem die Erde im Großen darstellenden Ellipsoid ab 4 The "Mitteleuropäische Gradmessung" : weicllt ... ". Baeyer's ldea and its Realiza tion
In the repo rt on th e arc measurement in Hannover (G auß After the East Prussian arc measurement ßaeyer promotes 1828) we then find the definition: rapidly, and fin ally Ieads the trigonometri c department of the Gene ral Staff ( 1843- 1857). Un d er his direction, new "... was wir im geo metrischen Sinn Ob erflä che der Erde tri angulation chains are spread out over Prussia, which nennen, ist nichts anderes als diejenige Fläch e, welche now fo ll ow the high Standards se t by Bessel. Further on, überall die Richtung der Schwere senkrecht schneidet, proper connections to neighbourin g countries play an und 110n der die Obe1jliiche des Weltm eeres ein en Theil important rote. The "Küstenvermessung" ( 1837 -1842) ausmacht ... ". connects the trigonometric network in East Prussia wi th the Danish triangulation, and the later fu ndamental sta Thi s means the introduction of a physica lly de fined fi gure tion Rauenberg origina tes from a chain to the triangula of the Ea rth, later by Listing call ed "geoid": the grav ity tion araund Berlin ( 1842 -1845). The scale of the Prussian fi eld now becomes an essential part of geodesy! The el first ord er triangulation is improved by additional base lipsoid now plays the ro Je of a geometri ca lly simp le Earth lines, and th e co nnection to the Russian triangulation is model, approxim ating the geoid: strengthened by furt her ties. Scale comparisons between the Russian and the Prussian baselin es and studies on "... Bei dieser Lage der Sache hindert aber noch nichts, the mean sea Ievel of the Baltic Sea already indicate fo die Erde im ganzen als ein Re!Jo lution ssphiiroid zu be cal points of the later "Mitteleuropäische Gradmessung", tracllten, 110 n dem die wirkliche (geometrische} Ober co ming into ex istence with the approval of Baeyer's "Ent fläche übera ll bald in schwiich em, bald in kiirzem , wurf zu ei ner mitteleuropiiisclren Gradmessung" ( 1861), bald i11 lii 11gem Undulatio11e11 abweicht ... ". see below. The idea to this proposal certain ly builds up on the well -known considerations of Zach, Ga uß, Miiffling, Gauß also exp resses the idea of a Europea n arc measure ment, as later rea lized by ßaeyer:
"... 11 ielleicht ist die Aussicht 11icht chimiirisch, dass ei 11st alle Stemwarte11 11011 Europa trigo11o metrisch un ter ei11a 11der 11erbu11den sein werde11 ... ". ln co nnection with the arc measurement in East Prussia, Fig. 4: Bessel also states that the real "mathematica l" Earth fi g Johann Jacob Baeyer ure may significa ntly dev iate from a rotational ellipso id: (1794-1885), faund er of the "Mitteleuropäische "... We1111 111 011 auch diese Obe1jliiche der Erde im ga nzen Gradmessung". Oil als der Obe1jläche ei11 es elliptischen RotatiOIISSphiiroi pa int ing by Stankiewicz Deu tsches Geofo rsc hungszentrum des nahe komme11 d betrachtet, so ka1111 man doch 11icht Potsdam. from Buschmann (1994) liiugnen, dass beide nicht r1ollkommen z rr sa11nn enjal-
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Struve ancl Bessel, bu t refinement and realization are af ~dv.~l' fected by different additional events and factors (Dick 1994, Dick 1996, Torge 2005). r, ~:~~ //bdd~/Y- ~-Ju.._,.~ Starting point for the development of this proposal is Bayers retirement in 1857, which is con nected wi th a far-reaching discordance with the Prussian General Staff. The quarre! originates from fu nd amentally differ ent opinions on the survey of a state, but is also touched by perso nal problems. Baeyer had meanwhile reached the rank of a Major-General, and could no t further adva nce within the General Staff (Fig. 4). A return to the practi cal military service as chief of a brigade was planned, although Alexallder voll Hu mboldt argued that "the King of Prussia owns sufficient officers fo r co mmand ing a brigade, but only one Baeyer". Th e appoin tment of HelmutiJ voll Moltke (being younger than Baeye r) as ch ief of the General Staff finally led to an only short-li ved construction - under "characterizing" (i. e. obtaining the corresponding rank but remaining wi th the wages of the previous position) as Lieutenant-General, Baeyer is put to the disposition of the new chi ef. The further devel opment is positi vely influenced by the fact that Wi/helm Fi g. 5: Hand-written draft (first and last lines) of Stru lle, now di rector of the recently established Pulkova Baeyer's memorandum (1861) for the foundation of a observatory, thi s year travels through Europe in order to "Mitteleuropäische Gradmessung", from Dick (1994) advertise his plan of a longitude arc measu rement, run ning along 52• latitude fro m Omsk/Ural to Va lencia/Ire land. Following a proposal from Struve, Baeyer is charged with the Prussian part of this international project. With respect to the necessary support, he unfo rtunately de pends on the good wi ll of the General Staff - the of llcl.ar olic fi cers detached to him are withdrawn agai n and agai n. Additionally, in 1859 there arises a c:on fli ct with Otto Griissc und Figur tlcr Et·dc. Stru ve who had followed his father Wi/he/m at Pulkova observatory. The younger Stnwe intends to take over the direction of the longitude arc measurement and its evalu ation - this is not acceptable for the elder an d far more ex perienced Baeyer. Ab out 1860, Baeyer probably reflects lhe first time upon an arc measurement in central Europe, for the prese nt concentrated on Germany. Th is becomes visible through a dedicated voyage to Munich where he
c i 11 c r meets an obvious interest at the Bavarian General Staff and the cadastral adm inistra ti on, lhe idea of a memoran dum fo r rea lizing such a project ori ginates here (P ieper J, ,lJ, !11\c ycr,
{;fOIIU IIo•oo""Utl t lt ; ~.... ,..,i,:n,. \ll(lo~.l J~r li:unld. •.-lo•t,IJo,h~• 1 ..-t .t,.-,,J~ , 1996). .;..,,...,,,Jhh.Uof,..,•,.,",I'....," '"''..,""'' •"''I'W ._.,..,,,""~'\l•.l'••t'>!rr\\o. • .-lo~nr .. , .. !Ct I'""'.Iot''"', t:s....-.. ,..,,c...., ·•·• " t: (,.. ,,,1-s.: .. r. .... ,;,,,tr,. • • u '" \l o•lt 1111ol Wol; 137. Jg. 3/2012 zfv 1 71 Fachbeitrag Torg e, 150 Years of International Cooperation in Geod esy ... ".. . Die beiliegende Übersichtskarte giebt ein anschau liches Bild 110 11 der Vertll eilung der astronomisch fest gelegten Punkte, an denen die Krüm11tung der Erd obetjläclle ... ermittelt werden kann. Innerha lb dieses Rahmens köntten noch etwa 10 Meridianbögen unter 11erscltiedenen Längen und noch mehr Parallel-Bögen unter 11erschiedene11 Breiten berec/111et werden; ... Kurz, es bietet sielt ein weites Feld 110 11 wisse11 selwftliche11 U11 tersuchunge11 dar; ... die ullzweifellwft zu ebe11 so i11teressa11te11 als wichtigeil Ergeb11issen führeil miis sell ... Ei11 solches Werk ka 111 t aber ... 11icllt das Werk eines ei 11 zel11 e11 Staates sei11 ; ... Wa s aber der Ei11zel11e 11icht tJemwg, da s geli11gt 11ielen! ... Wenn daher Mittef Europa sielt 1m·ei11igt ... so ka1111 es ein bedeulullgsllol les, grossartiges Werk i11 s Lebeil rufeil ... ". The proposed project contai ns about 30 astronomic ob ~--r---1 . t _____.. servatories which already are or should be geodetically co nnected through triangulation chai ns, and it covers an ·~~~~~~~~==~-~- --- · area of about 13° of difference in longitude and 29° dif 1 ferences in la titude, respectively (Fig. 7). The main objec \ tive - determination of the curvature anomalies of the Ea rth figure - is exten ded by including the interpretation ~~~ r of th e results. This is speci fi ed by examp les, as the ef \ . fect of the Alps on the deflections of the vertical, and an eventually anomalous gravity fiele! behaviour at the \ .J ,. European border seas: the geo physical-geological inter \ pretation of the geodeti c results is a component part of .. the project! __.L l· On 20'11 June 186 1 - only two months after presenting his memorandum! - Baeyer's plan is approved by order Fig. 7: Network sketch of the "Mitteleuropäische of the Prussian royal cabinet, and the Prussian Foreign Gradmessun g": Astronomi cal observatories and geodesics Ministry asks the governments of the other central Eu to be computed from tria ngulation (Baeyer 1861) ropean countries fo r collaboration. This rapid positive decision is to a !arge part due to the protection of Fürst [all ows the use of data necessary for the project). Italy, Ca rl A11to11 110 11 Hoh ell zollem-Sigmarillgell , pres ident of The Netherlands, Polami [through Russia), Sweden and the State Ministry (Dick 1996). Already in April 1862 No rway (in personal union), and Switzerland. This is a First negotiations betwee n representatives of the states of great success: an international collaboration fo r a scien Pruss ia, Austria and Saxony take place in Berlin, with the tific project reaching far beye nd ce ntral Europe has bee n fo llowing participants: Jolwtllt Ja cob Baeyer, Li eutenant approved by the respective governments, and is carried General z. D., Prussia; August 110 11 Flige/y, Major-General by leading representatives of science and military geog and Director of the Mi litary-Geographie Institute Vienn a, raphy. The next step to be taken co mp rises the Formation Austria; Carl IJOII Littrow, Di rector of the Astronomie of an effective organization and a more specified def1n i Observ atory Vi enna, Austria; Josef Herr, Professor for tion of the problems to be attacked. Spherical Astronomy an d Higher Geodesy, Po lytechnical School Vienna, Austria; Julius Ludwig Weisbach, Profes sor fo r Mathematics at the Royal Montanistic Academy 5 Orga ni za tion and Scientific Prog ra m: Freiberg, Saxony; Christiall August Nagel, Professor of the 'Baeyer' Epoch 1862-1886 Geodesy, Polytechnical School Dresden, Saxo ny; Carl Christiall Bru h11 s, Professor of Astronomy, University of In hi s ge nera l report ( 1862}, Ba eyer had already plan ned Leipzig, Saxony. to subdivide his project into internal, borAer crossing, At the end of 1862, Baeyer presents a "General-Bericht and comm on work. Special and general conferences are üb er den Sta nd der mitteleuropäischen Gradmessung", proposed for discussion, and a central bureau shall be es where he is able to identi fy 16 states or co un tri es that had tablished in Berlin, being responsible for compilation and entered the project. These are the seven German states reporting of the results. In 1864, the Arst "General Co n Baden, Bavaria, Hannover, Mecklenburg, Prussia, Saxony ference of the Representati ves to the Ce ntral European and Saxe-Gotha, and Austria, Belgium, Denmark, France Are Measurement" takes place in Berli n, and fi xes the or- 172 zfv 3/2012 137. Jg. Torge, 150 Years of Internationa l Cooperation in Geodesy ... Fachbeitrag ga nizational structure as weil as the research programm e. Further achievements of this first phase of internation The organization includes the Permanent Co mmission, al co ll aboration may be described by the words "Metric meeting annually and responsible fo r the scientific man System and International Bureau for Weights and Mea agement, the Central Bu reau as an executive, and General sures", "precise leveling and determination of mean sea Co nferences at three-yearly intervals - a structure which Ievel", "European longitude network", "Greenwich zero is still visible today at the International Association of meridian and universal time", and "absolute gravity mea Geodesy. The work is divided into th ree secti ons, related surements with the Repsold pendulum apparatus" (Torge to organi zational affairs, astronomic and physical prob 2005) . A remarkable step Forward at geodetic theory is lems, and geodetic tasks. Among the probl ems to be at due to Em st Hei11ricll Bn111s, Professor of Mathematics at tacked we find the regulation of the unit of length, grav the Un iversity ofBerlin and later (since 188 1) Professor of ity measurements, and a unified height system. Astronomy at the University of Leipzig. Triggered by the The membership Iist of the first Genera l Co nference geodetic activities of the "Mitteleuropäische Gradmes naturally shows the predominance of the representatives sung", he publishes a study on the fundamental problem of the German states, and until the 1880's the German of geodesy which Iooks far into the Future and contains influence is also visible in the location of the General concl usions fo r the scientific programme of the Are Mea Co nferences. Bu t already in 1867, after Po1t ugal, Spain surement organization (Bruns 1878). and Russia had joined th e project, the name of the or The death of Baeyer ( 1885) finishes the first phase ga nization was changed to "Europäische Gradmessung". of an organized coll aboration in scientific geodesy. His With Baeyer as president, th e Central Bureau starts work achi evement for the creation of an international (govern in 1866. ln 1870 the Prussian Geodetic Institute is estab mental) geodetic organization has been acknowledged lished in Berlin and entrusted with the operation of the several times already during his li fetime. At the General Central Bureau, Baeyer becomes its fi rst director (Lait Co nference held in Rome 1883, the Italian Are Measure ko 1996) . Although this first period of the lAG is gov ment Co mmission honoured him with a gold medal car erned by the outstanding personage of Baeyer, the work rying the Iaudation : of the presidents of the Perm anent Commission should also be acknowledged. These were Peter A 11dreas Ha11 se 11 "J.J. ßaeyero qui ad terrae me11 suras co mmu11i studio ( 1864 - 1868), Director of the Gotha Observa t01y, August enteildas 11atio11um sodalitium e.rcitaiJit ltali labon1111 vo 11 Fligely ( 1869 - 187 4), General (see above), and Carlo s socii i11 co 11 ve11 tu septimo Romae MDCCCLX.XXl/1" lbci1i ez e lbci1iez de fb ero ( 1874-1886), Generaland Direc ("Dem J. J. Baeyer, der die Ge meinschaft der Nationen tor of the Geograph ical and Statistkai Institute, Mad rid. zur Erforschung der Erdmessungen im gemeinschaft Fo ll owing the program of the "Mitteleuropäisc he lichen Studium anregte, di e italieni schen Arbeitskolle Gradmessung", triangul ation is progressing rapidly in gen auf der 7. Konferenz in Rom 1883" - Übersetzung the European countries. A remarkable enterprise is th e E. Knobloch, Pieper 1996). connection of the Spanish triangulation with Al geria ( 1879), where triangles with a maximum siele length of Geo rges Perrier, the long-standing secretary genera l of 270 km are observed from mountain stati ons, under the the successor organization "Association In ternationale de direction of General lbci 1iez and Major F. Perrier, Chief of Geodesie" apprecia tes him with the wo rds: the geodetic section of the French General Staff. We also mention the new tri angul ation of the Kingdom of Sax "Als Baeyer starb, hatte er, da11k ei11 er ziill e11 Arbeit, ony ( 1867- 1878) ca rried out by Nagel (see above), setting fii r sei11 La11d ei11 e11 erste11 Platz i11 der Geodäsie er new standards with respect to the quali ty of measurement obert ... " (Tardi 1963). and computation. In Prussia, curiously enough, severe proble111S arise at rea lizing the demands of the project. This is due to theseparate responsibility fo r the triangu lati on of the state (remains at the General Sta ff) and of 6 From the "Europäische Grad messung" to the arc measurement project (Geodetic Institute). In this the "International Association of Geodesy": co nn ection, Baeyer declares that all measurements of the Global Extension and Strengthening of General Staff ca rried out since 1858 (Ba eyer had retired lnterd isciplinary Relation in 1857 !} did not satisfy th e scientific demands of the arc measurement project. The follo wi ng confrontation with The fu rther development of the scientific organiza the General Staff also involves several mem bers of the tion fo unded by Baeyer can be sepa ra ted in to several Permanent Commission, and lasts until Baeyer's death phases, and a number of repo rts is available describing (Pieper 1996). On the other hand, as the Prussian army thc changes and the scientifi c achi evements which oc was not too popular in the co untries around Germany, curred after the "Baeyer" epoch (e.g. 1-Ielmert 1913, Hun due to the wars th at led to th e unification of Germany ger 1962, Levallois 1980, To rge 1996, Adam 2008). The in 1871, Baeyercertainly gained a Iot ofsympathy, espe "Helmert" epoch ( 1886 - 191 6) is governed by "einem der cia lly with the mili ta1y representatives ofthose countries. beJiihm testen Geodäten de r modern en Zeit" (Tarcl i 1963). 137. Jg. 3/2012 zfv 173 Fachbeitra Torge, 150 Years of International Cooperation in Geodesy ... Friedriclt Robert Helliiert held the chair of Geodesy at H. G. va 11 de Sa 11de Baklwyze 11 , Directors of the Geneva the Technical University of Aachen sin ce 1870, hi s two ancl the Leyclen Observato ry, respectively, who organize voltllne book "Die mathematischen und physikalischen an "Association Geodesique reduite entre Etats Neu Theorien der höheren Geodäsie" ( 1880/ 1884) arguably tres" (Torge 2005). After the First World War, interna establi shed geodesy as a proper science (Wolf 1993). He tional science organizecl itself within the Frame of non became Director of the Prussian Geodetic Institute and govern mental organiza tions, amo ng them is the "Un ion the Central Bureau in 1886, and held this position un Geodesique et Geop hysique Internationale", founded in til his death in 1917. The arc measurement organization 1919. A Section ofGeodesy is constituted in 192 2, which is immediately extended to a globa l association call ed in 1932 adopts the name "International Association of "Intern ationale Erdmessung" ("Intern ational Geodetic As Geodesy". As the central powers (G ermany and its al sociation"), and th e scientific programme is significantly lies) originally remain exclud ed fro m this organization, enlarged (Torge 1993, Torge 2005) . Until 18 89, the United Germany becomes a member country only in 1937 . The States of America, Mexico, Chil e, Arge ntine and Japan Seco ncl World War again interrupts in ternational col agreed with the new convention, and Great Bri ta in joined laboration, but now the Fecleral Republic of Germany is the Association in 1898. An annual financial contribu admitted as a member of the "In ternational Un ion of Ge tion from the countries strengthened the power of the oclesy and Geophysics" (IUGG) already in 1951, follo wed Association, and the change of the voti ng procedure at by the Germ an Democ ratic Repub lic in 1964. the General Co nferences (one voice per coun try) reduced Embeclded in the wide spectrum of geophysical dis the overwhelming influence of the Germ an states. The ciplines, the scientific work of lAG especially since the more international character of the Association can be 1950's not only Fellows classical directions, but increas seen also from the location of the General Co nferences, ingly co ntributes to an interdiscip li nary unclerstand ing with Paris (1889), Brussels (1892), Berlin (1895), Stuttgart of the system Earth. The fund amental problems of ge ( 1898), Paris ( 1900), Copen hagen ( 1903), Budapest ( 1906), odesy, i. e. the determination of the Earth figure, gravity London and Cambridge ( 1909), and Ham burg ( 1912). fi ele!, and rotation, are now mainly attacked by means The scientific program naturally further on includes of geodetic space methocls and mi ssions. The focal point the determination of the geo id curvature, but the collec of research and service has sh ifted more and more to the tion and evaluation of the corresponding data is extended measurement, interpretation, and eventually prediction on the whole globe. The geodetic problem of deriving a of temporal vari ations (e.g. Beutler et al. 2004, Plag and geometric and gravimetric Ea rth model is supp lemented Pearlman 2009, Drewes 2012). But lAG, looking back now by investigati ons on isostasy. Precise leveling is available on a history of 150 years, still remembers with pride and now fo r !arger areas and exploited for the investigation gratitude its origin and the foundation initiated and rea l of sea Ievel slope and vertical crustal movements. The ized by Joha1111 Jacob Baeyer. A special session on the mtmber of gravity measurements increases significantly, history and development of lAG is scheduled at the lAG due to the development of a relative pendulum apparatus Scientific Assembly tobe held in Potselam in 201 3. by R. v. Stemeck. This raised th e problem of a gravity reference system, solved by a th orough absolute grav ity determination at the Geodetic Institute Potselam and References the introducti on of the "Potsdam Gravity System", valid Adam, J. (2008): The International Association of Geodesy (lAG). until 197 1. Gravity measurements on the aceans give a J. Geodesy 82: 662 - 674. Baeyer, J.J. I 1861): Über die Größe und Figur der Erde, eine Denkschrift Fi rst impression on the isostatic behaviour of the ocean zur Begründung einer mittel -europäischen Gradmessung. G. Reimer, areas. Gravity fi ele! modeling starts but is still restrict Berlin. ed on small er and weil surveyed test areas, as the Harz Beitr. Baeyer-Symp. I 1996): Beiträge zum J. J. Baeyer-Symposium, Ber mountains. The related problem of gravity reduction to lin- Köpenick, 5.- 6.11 . 1994. Deutsche Geod. Komm., Reihe E, Nr. 25, Frankfurt a. M. the geoid is investigated intensively, with several solu Beutler, G., Drewes, H., Verdu n, A. (2004): The new structure of the tions valid until today. The time component of the geo International Association ofGeodesy (lAG) viewed fromthe perspec detic measurements and th e inherent infonnation fo r as tive of history. J. Geod. 77: 566- 575. tronomy and geophysics is also clea rly recognized in thi s Bia las, V. (1 982): Enlgestalt. Kosmologie und Weltanschauung. K. Will wer, Stuugart. epoch. Among the outstanding examples of this arisi ng Brosche, P. (2001): Der Astronom der Herzogin - Leben und Werk von "four-dimensional" geodesy is the observation of polar Franz Xaver von Zach. 1-larri Deutsch, Frankfurt a. M. motion which Ieads to the establishm ent of the Inter Bruns. H. 11878): Die Figur der Erde - Ein Beitrag zur europäischen national Latitude Service, as weil as First measurements Gradmessung. P. Stankiewicz, Berlin. Buschmann. E. • Hg. ( 1994): Aus Leben und Werk von Johann Jacob of the solid Ea rth tides. Baeyer. Institut fiir Augewandte Geodäsie, Frankfun a. M. The convention on the "Internationale Erdmessung" Dick, W.R. (1994): Die Vorgesch ichte von Johann Jacob Baeyers "Em expired at the end of 1916, and was not extencled du e wmf zu einer Mittckmopäischen Gradmessung·: ln: Buschmann to the First Warlei War. Fo rtunately some activities of 11994): 105-144. Dick, W. R. ( 1996): Zur Vorgeschichte der Mitteleuropäischen Grad the Association co uld be co ntinued, especially the Lati messung. ln: Beiträge zum J. J. Baeyer- Symposium. Deutsche Geod. tude Service. This is clue to the efforts of R. Ga utier and Komm., Reihe E, Nr. 25: 15- 27, Frankfurt a. M. 17 4 zfv 3/2012 137. Jg. Drewes, Cu rren t Activi ties of th e International Associa tion of Geodesy (lAG) ... Fachbeitrag Drewes. H. (2012): Current Activities of the lmernational Association of Pe11e rsen, B. R.. Müller, J. (2009): Small Instrument - Big Task. A Histo Geodesy (l AG ) as the Successor Organisation of the Mitleieuropäi rical Accou nt of how a Repsold Universal lnstrumem came to serve sche Grad messung. zfv 137 : 175- 164. at the Arctic End of thc Struve Geodetic Are. zfv 134: 348- 357. Eggen, 0. (1 911 ): Bessel als Geodät. Z. f. Verm.wcsen 40:301 - 310. Pieper. H. (1 996): Johann Jacob Baeyer. In : Beit r. Baeyer-Symp. ( 1996): Gauß und die Landesvermessung in Niedersachsen ( 1955): Herausg. von 69- 11 9. der Nicders. Vermessungs- und KatasteJverwaltung. Nieders. Lan Plag. 1-1 .-P., Pearlman. M.. eds. (2009): Global Geodetic Obse1ving Sys desvermessungsann Han nover. tem. Springer, Berl in- Heidelberg. Gauß, C. F. ( 16 26) : Bestimmung des Breitenumerschiedes zwischen den Soldner, J. (1610) : Theorie der Landesvermessung. Herausg. von J. Fri Sternwarten von GöHingen und Altona. in: C. F. Gauss Werke, neun schauf, Ostwaids Klassi ker der Exakten Wissenschaften Nr. I 64, ter Band. Herausg. v. d. Königl. Gesellsch. d. Wissensdt. zu Göllin W. Engelmann, Leipzig 1911. gen, B.G. Teubner. Leipzig 1903. Strasser, G. ( 1957): Elli psoidische Parameter der Erdfigur (I 800- 1950). Großmann, W. ( 1955): Niedersächsische Vermessungsgeschichte im Deutsche Geod . Komm .• Reihe A, Nr. 19, München. 16. und 19. Jahrhundert. in: Gauß und die Landesvermessung in Tanli, P. (1963): Hundert Jahre Internationale Erdmessung. Z. r. Verm. Niedersachsen ( 1955): 17- 59. wesen 88: 2- 10. 1-i amel, J., Buschmann, E. (1 996): Friedrich Wil helm Bessels und Johann Torge, W. ( 1993): Von der mitteleuropäischen Gradmessung zur Interna Jacob Baeyers Zusammenwirken bei der .. Ostpreußischen Gradmes tionalen Assoziation für Geodäsie. Z. f. Ve rm .wesen 116: 595- 605. sung.. 1630- 1636. 1n: ßeitr. ßaeyer-Symp. (1 996): 45- 57. Torge, W. ( 1996): The International Association ofGeodesy (l AG) - More I-leimen, F. R. ( 1913): Die Internationale Erdmessung in den ersten fün f than 130 years ofinternational cooperation. J. Geodesy 70:640- 845. zig Jahren ihres ßestehens. lmernat. Monatsschri ft für Wissenschaft, Torgc, W. (2002): Müfnings geodätisches Wirken in der Umbmchepoche Ku nst und Technik, ßerlin: 397- 424. vom 18. zu m 19. Jahrhundert. Z. f. Verm.wesen 127: 97- 108. Hunge r, F. (1962): Hundert Jahre lmernationale Erdmessung. Z. f. Verm. Torge, W. (2005): The lmernational Association of Geodesy I 662 to wesen 67: 117 - 125. 1922: from a regional project to an international organization. Laitko, H. ( 1996): Johann Jacob ßaeyer, die internationa le Stellung des J. Geodcsy 78: 558- 568. Preußischen Vermessungswesens und die Mitteleuropäische Grad Torge, W. (2009): Geschichte der Geodäsie in Deutschland. 2. Aun., de messung. Dahlemer Archivgespräche, Band I: 56- 76, ßerli n. Gruyter, ßerlin-New York. Lehmann, G. (1955): Gauß' theoretische geodätische Arbeiten. In: Gauß Wolf, H. (1 993): Friedrich Roben Helmert - sein Leben und Wirken. Z. F. und die Landesvermessung in Niedersachsen ( 1955): 60- 62. Vcrm .wesen 118:582- 590. Lemke, D. (20 11): Die Vermessung der Erde. Sterne und Weltraum Nr. 6: 42- 50. Levall ois, J.J. (1960): The history of the International Association of Geodesy. The Geodesist's Handbook - ßull. Geod. 54: 249- 313. Author's adress Perrier, G. ( 1939): Petite Histoi re de Ia Geodesic. Comment l'homme Prof. (em.) Dr.-lng. Wolfga ng Torge a mesun' ct pese Ia Terrc. Alcan, Presses Univers,i taires de France, Institut für Erdmessung, Lei bniz Universität Hannover Paris. German translation by E. Gigas (1950) : Wie der Mensch die Schneiderberg 50, 30167 Hannover Erde gemessen und gewogen hat - Kurze Geschichte der Geodäsie. Bamberger Verlagshaus Meisenbach, Bamberg. Current Activities of the International Association of Geodesy (lAG) as the Successor Organisation of the Mitteleuropäische Gradmessung* Hermann Drewes Summa ry Zusammenfassung Th e Internati onal Association of Geodesy (lAG) is a consti Die Internationale Assoziation für Geodäsie (lAG) ist eine kon tuent Association of the International Union of Geo.desy and stituierende Assoziation der Internationalen Union für Geo Geophysics (IUGG) since 1922, and the successor organi zation däsie und Geophysik {IUGG) und die Nachfolgeorganisation of the Mitteleuropäische Gradmessung. lts activities have der Mitteleuropäischen Gradmessung. Ihre Aktivitäten haben changed dramatically from its beginning in 1862 till today. sich seit dem Beginn im Jahre 1862 bis heute dramatisch ver Whi le it started with the aim of determining th e regional ändert. Während das Ziel anfangs die Bestimmung regiona anomalies of the Earth's curvature in Europ e by co nnecting ler Anomalien der Erdkrümmung in Europa durch Verbindung astronom ical observa tori es throu gh triangu lation networks, der astronomischen Observatorien mit Triangulationsnetzen it concentrates now on the Observation and modelling of the war, konzentrieren sich die Arbeiten heute auf die Beob ph enomena and effects of physical processes in the System achtung und Modeliierung der Erscheinungen und Effekte Ea rth emp loying mainly spa ce techniqu es. Th e structura l and scientific developm ents over time are summari sed, and the present structure and activities are described in detail. • Modifi zierte und ins Englische übersetzte Fassung eines Vor trages im Rahmen des Festkolloq uiums • 150 Jahre Mi tteleuro päische Gradmessung in Sachsen• am I. Juni 20 12 in Dresden. 137. Jg. 312012 zfv 175