Friedrich Hopfner (28 October 1881 – 5 September 1949) was an Austrian

geodesist Geodesy ( ) is the Earth science of accurately measuring and understanding Earth's figure (geometric shape and size), orientation in space, and gravity. The field also incorporates studies of how these properties change over time and equivale ...

geophysicist Geophysics () is a subject of natural science concerned with the physical processes and physical properties of the Earth and its surrounding space environment, and the use of quantitative methods for their analysis. The term ''geophysics'' so ...

and

planetary scientist Planetary science (or more rarely, planetology) is the scientific study of planets (including Earth), celestial bodies (such as moons, asteroids, comets) and planetary systems (in particular those of the Solar System) and the processes of th ...

. As an officer of the

Austro-Hungarian Empire Austria-Hungary, often referred to as the Austro-Hungarian Empire,, the Dual Monarchy, or Austria, was a constitutional monarchy and great power in Central Europe#Before World War I, Central Europe between 1867 and 1918. It was formed with t ...

he began his scientific work at the Bureau of

Meteorology Meteorology is a branch of the atmospheric sciences (which include atmospheric chemistry and physics) with a major focus on weather forecasting. The study of meteorology dates back millennia, though significant progress in meteorology did no ...

. In 1921 he became Chief

Astronomer An astronomer is a scientist in the field of astronomy who focuses their studies on a specific question or field outside the scope of Earth. They observe astronomical objects such as stars, planets, moons, comets and galaxies – in either o ...

at the new Geodetic Survey of Austria ( Federal Office for Metrology and Survey or ''Bundesamt für Eich- und Vermessungswesen''). From 1936 to 1942 and from 1945 to 1949 he was a professor at the

Vienna University of Technology TU Wien (TUW; german: Technische Universität Wien; still known in English as the Vienna University of Technology from 1975–2014) is one of the major universities in Vienna, Austria. The university finds high international and domestic recogn ...

(TU Wien) and over the 1948-9 term he was the university's

rector Rector (Latin for the member of a vessel's crew who steers) may refer to: Style or title *Rector (ecclesiastical), a cleric who functions as an administrative leader in some Christian denominations *Rector (academia), a senior official in an edu ...

Life

He was born on 28 October 1881 in Trautenau, northern Bohemia (now

Trutnov Trutnov (; german: Trautenau) is a town in the Hradec Králové Region of the Czech Republic. It has about 29,000 inhabitants. The town centre is well preserved and is protected by law as an urban monument zone. Administrative parts Trutnov is ...

Czech Republic The Czech Republic, or simply Czechia, is a landlocked country in Central Europe. Historically known as Bohemia, it is bordered by Austria to the south, Germany to the west, Poland to the northeast, and Slovakia to the southeast. Th ...

). He studied mathematics,

physics Physics is the natural science that studies matter, its fundamental constituents, its motion and behavior through space and time, and the related entities of energy and force. "Physical science is that department of knowledge which rel ...

geophysics Geophysics () is a subject of natural science concerned with the physical processes and physical properties of the Earth and its surrounding space environment, and the use of quantitative methods for their analysis. The term ''geophysics'' som ...

and

astronomy Astronomy () is a natural science that studies astronomical object, celestial objects and phenomena. It uses mathematics, physics, and chemistry in order to explain their origin and chronology of the Universe, evolution. Objects of interest ...

at the University of Prague and the

University of Munich The Ludwig Maximilian University of Munich (simply University of Munich or LMU; german: link=no, Ludwig-Maximilians-Universität München) is a public research university in Munich, Bavaria, Germany. Originally established as the University of ...

between 1899 and 1904. In 1905 at the

Charles University in Prague ) , image_name = Carolinum_Logo.svg , image_size = 200px , established = , type = Public, Ancient , budget = 8.9 billion CZK , rector = Milena Králíčková , faculty = 4,057 , administrative_staff = 4,026 , students = 51,438 , undergr ...

he delivered his dissertation on "The average and relative distribution of temperature on the Earth's surface." His first job was as an assistant at the

Prague Observatory Prague ( ; cs, Praha ; german: Prag, ; la, Praga) is the capital and largest city in the Czech Republic, and the historical capital of Bohemia. On the Vltava river, Prague is home to about 1.3 million people. The city has a temperate ...

, and then at the Bureaux of Meteorology in

Berlin Berlin is Capital of Germany, the capital and largest city of Germany, both by area and List of cities in Germany by population, by population. Its more than 3.85 million inhabitants make it the European Union's List of cities in the European U ...

, Innsbruck and

Vienna en, Viennese , iso_code = AT-9 , registration_plate = W , postal_code_type = Postal code , postal_code = , timezone = CET , utc_offset = +1 , timezone_DST ...

. In 1908 he transferred to the Maritime Observatory in

Trieste Trieste ( , ; sl, Trst ; german: Triest ) is a city and seaport in northeastern Italy. It is the capital city, and largest city, of the autonomous region of Friuli Venezia Giulia, one of two autonomous regions which are not subdivided into pr ...

(now the ''Istituto Talassografico di Trieste'' or ITT), then in 1912 to the Bureau of Geodesy (''Gradmessungsbüro'') in Vienna. During

World War I World War I (28 July 1914 11 November 1918), often abbreviated as WWI, was List of wars and anthropogenic disasters by death toll, one of the deadliest global conflicts in history. Belligerents included much of Europe, the Russian Empire, ...

he was head of the meteorological service for the Isonzo Army of

Austria-Hungary Austria-Hungary, often referred to as the Austro-Hungarian Empire,, the Dual Monarchy, or Austria, was a constitutional monarchy and great power in Central Europe between 1867 and 1918. It was formed with the Austro-Hungarian Compromise of ...

. In 1921 he became Chief

at the new Geodetic Survey of Austria ("Bureau of Weights, Measures and Surveying" or ''Bundesamt für Eich- und Vermessungswesen''). In 1936 he was appointed Professor of Theoretical

Geodesy Geodesy ( ) is the Earth science of accurately measuring and understanding Earth's figure (geometric shape and size), Earth rotation, orientation in space, and Earth's gravity, gravity. The field also incorporates studies of how these properti ...

and

Spherical astronomy Spherical astronomy, or positional astronomy, is a branch of observational astronomy used to locate astronomical objects on the celestial sphere, as seen at a particular date, time, and location on Earth. It relies on the mathematical methods of ...

at the

, as successor to

Richard Schumann Richard is a male given name. It originates, via Old French, from Frankish language, Old Frankish and is a Compound (linguistics), compound of the words descending from Proto-Germanic language, Proto-Germanic ''*rīk-'' 'ruler, leader, king' an ...

. In autumn 1942 he declined Hitler's invitation into his newly created Academy of Sciences (''Akademie der Wissenschaften'') in Prague, and was forced into retirement, moving with his family to Schönbühel on the

Danube The Danube ( ; ) is a river that was once a long-standing frontier of the Roman Empire and today connects 10 European countries, running through their territories or being a border. Originating in Germany, the Danube flows southeast for , ...

, where he devoted himself exclusively to research. After the war he was restored to his position in Vienna, and was later elected Dean of the Faculty of Applied Maths and Physics. His pleasant friendliness made him popular with colleagues and students, and in the 1948-9 term he was voted ''

Rector magnificus A rector (Latin for 'ruler') is a senior official in an educational institution, and can refer to an official in either a university or a secondary school. Outside the English-speaking world the rector is often the most senior official in a u ...

'' at the Technical High School of Vienna. In the last month of his incumbency, he drowned in a boating accident on the

Hintersteiner See Hintersteiner See is a mountain lake in the Wilder Kaiser Austrian national park and belongs to the administrative region of Scheffau in the Austrian federal state of Tirol. The , lake was created during the last ice age and is at a height of 88 ...

, near

Kufstein Kufstein (; Central Bavarian: ''Kufstoa'') is a town in the Austrian state of Tyrol, the administrative seat of Kufstein District. With a population of about 19,600 it is the second largest Tyrolean town after the state capital Innsbruck. The gr ...

Work

From the very beginning of his career he made valuable contributions to

geodesy Geodesy ( ) is the Earth science of accurately measuring and understanding Earth's figure (geometric shape and size), Earth rotation, orientation in space, and Earth's gravity, gravity. The field also incorporates studies of how these properti ...

and

meteorology Meteorology is a branch of the atmospheric sciences (which include atmospheric chemistry and physics) with a major focus on weather forecasting. The study of meteorology dates back millennia, though significant progress in meteorology did no ...

, in the applied fields as well as the theoretical, and published a great deal on all four subjects. He wrote three well-known textbooks.

Trajectories of planetoids

Hopfner's early work was mostly concerned with astronomy and meteorology. In collaboration with

Johann Palisa Johann Palisa (6 December 1848 – 2 May 1925) was an Austrian astronomer, born in Troppau, Austrian Silesia, now Czech Republic. He was a prolific discoverer of asteroids, discovering 122 in all, from 136 Austria in 1874 to 1073 Ge ...

, he determined the

trajectories A trajectory or flight path is the path that an object with mass in motion follows through space as a function of time. In classical mechanics, a trajectory is defined by Hamiltonian mechanics via canonical coordinates; hence, a complete traj ...

and

ephemerides In astronomy and celestial navigation, an ephemeris (pl. ephemerides; ) is a book with tables that gives the trajectory of naturally occurring astronomical objects as well as artificial satellites in the sky, i.e., the position (and possibly v ...

of a number of

planetoid According to the International Astronomical Union (IAU), a minor planet is an astronomical object in direct orbit around the Sun that is exclusively classified as neither a planet nor a comet. Before 2006, the IAU officially used the term '' ...

Mathematical foundations of a theory of climatology

In 1906 he began researching problems bordering both astronomy and geophysics, starting with the warming of the Earth by the Sun. We owe mainly to Hopfner the sharp distinction he made between the daily and seasonal average irradiation. In 1927 he went into the subject in more detail, laying out his discoveries in his ''Mathematical Foundations of an Astronomical Theory of Climatic Variation'' (''Mathematische Grundlagen zu einer astronomischen Theorie der Klimaschwankungen''), which won him the ''Seegenpreis''.

Research on tides

His work at the Maritime Observatory in

led him to study oceanographical questions, for example on tides and the determination of water levels in Trieste harbour, both very important practical problems.

Geodesy and geophysics

With his entry to the ''Gradmessungsbüro'' in 1921 he turned to

and

, in particular his work on the

meridian arc measurement Arc measurement, sometimes degree measurement (german: Gradmessung), is the astrogeodetic technique of determining of the radius of Earth – more specifically, the local Earth radius of curvature of the figure of the Earth – by relating the l ...

Großenhain Großenhain (also written as Grossenhain; hsb, Wulki Hojn) is a Große Kreisstadt (German for major district town) in the district of Meissen, Saxony, Germany. It was originally known as Hayne. The current name simply means "big Hayne" History ...

Kremsmünster Kremsmünster is a town in Kirchdorf an der Krems District, in the Austrian state of Upper Austria. Settled in 777, it is home to the Kremsmünster Abbey. The Abbey was founded 777 by Duke Tassilo III of Bavaria and is one of the oldest abbeys o ...

- Pola, which detailed the use of comparisons of

vertical deflection The vertical deflection (VD) or deflection of the vertical (DoV), also known as deflection of the plumb line and astro-geodetic deflection, is a measure of how far the gravity direction at a given point of interest is rotated by local mass anom ...

s. Later he studied the important problem of the

geoid The geoid () is the shape that the ocean surface would take under the influence of the gravity of Earth, including gravitational attraction and Earth's rotation, if other influences such as winds and tides were absent. This surface is exten ...

(the Earth's shape), for example through the reduction of observations of weight and the subject known as

isostasy Isostasy (Greek ''ísos'' "equal", ''stásis'' "standstill") or isostatic equilibrium is the state of gravitational equilibrium between Earth's crust (or lithosphere) and mantle such that the crust "floats" at an elevation that depends on it ...

(the study of gravitational equilibrium within the Earth). From the 1930s he concentrated on the study of the

reference ellipsoid An Earth ellipsoid or Earth spheroid is a mathematical figure approximating the Earth's form, used as a reference frame for computations in geodesy, astronomy, and the geosciences. Various different ellipsoids have been used as approximatio ...

and phase diagrams, as well as the elliptical shape of the Equator, the level spheroid, and the triaxial

Jacobi ellipsoid A Jacobi ellipsoid is a triaxial (i.e. scalene) ellipsoid under hydrostatic equilibrium which arises when a self-gravitating fluid body of uniform density rotates with a constant angular velocity. It is named after the German mathematician Car ...

Contributions to Austrian science

Hopfner did pioneering work on the determination of geographical distances without the use of wires (the first employment of time-signals), as well as on

gravimetry Gravimetry is the measurement of the strength of a gravitational field. Gravimetry may be used when either the magnitude of a gravitational field or the properties of matter responsible for its creation are of interest. Units of measurement Gr ...

. His study of the Earth's magnetic field helped make a name for the ZAMG, or Central Institute for Meteorology and Geodynamics (''Zentralanstalt für Meteorologie und Geodynamik'') in Vienna.

Memberships and responsibilities

* Member of the Austrian Academy of Sciences * President of the Austrian Geodetic Commission (ÖKIE, now ÖGK) * Correspondent to the Central Institute for Meteorology and Geodynamics (ZMG) * Corresponding member of the German Society for Science and the Arts in the Republic of Czechoslovakia * Member of the Mathematical Society of Vienna

Awards

* 1912 ''Oskar Freiherr von Rothschild-Preis'' for astronomy, from the Vienna Academy of Sciences * 1923 ''Seegenpreis'' from the Society for the Promotion of German Science, Art and Literature in Bohemia * 1931 Given the title ''Hofrat'' (Counsellor) * 1977 The Austrian Geodetic Commission begins awarding the ''Friedrich Hopfner-Medaille'' in his honour; it is given every four years for outstanding work in the field of geodesy

Bibliography

Hopfner published a total of eighty-one works. In this partial list, the three textbooks are indicated with bold type. * 1905 "Die Verteilung der solaren Wärmestrahlung auf der Erde", ''Monthly Weather Review'' (1906). * 1907 "Untersuchungen über die Bestrahlung der Erde durch die Sonne mit Berücksichtigung der Absorption der Wärmestrahlen durch die Atmosphärische Luft nach dem Lambert'schen Gesetz. Erste Mitteilung: Analytische Behandlung des Problems." (pp. 167–234) in: ''Über das Vorkommender seltenen Erden auf der

Sonne Sonne may refer to: Surname * Alma Sonne (1884–1977), general authority of The Church of Jesus Christ of Latter-day Saints (LDS Church) * Brett Sonne (born 1989), Canadian professional ice hockey centre for Dornbirner EC of the Austrian Hockey ...

'', Wien, Verlag Hölder * 1913 "Die

Gezeiten ''Gezeiten'' (German German(s) may refer to: * Germany (of or related to) **Germania (historical use) * Germans, citizens of Germany, people of German ancestry, or native speakers of the German language ** For citizens of Germany, see also Ger ...

im Hafen von Triest", Wien, Verlag Hölder, in: ''Sitzungsberichte der Akademie der Wissenschaften'', Math.-Nat. Klasse, Abt.2a; Bd.122, Heft 9, Wien * 1922 "Der :de:Meridianbogen Großenhain-

-Pola" (with R. Schumann), ''Astro-geodätische Arbeiten Österreichs'', Neue Folge Bd.1 * 1927 ''Mathematische Grundlagen zu einer astronomischen Theorie der Klimaschwankungen'' * 1927 Die Figur der Erde, Bundesverlag Wien * 1931 "Neue Wege zur Bestimmung der Erdfigur." (Ergebnisse der Kosm. Physik Bd.1), Leipzig * 1931 "Die Gezeiten der Meere" in ''Handbuch der Experimentalphysik'' * 1933 "Die Gezeiten der festen Erde" in Gutenberg's ''Handbuch der Geophysik'' * 1933 Physikalische Geodäsie (''Mathematik und ihre Anwendungen'', Bd. 14), Akademischer Druck, Leipzig * 1936 "Figur der Erde, Dichte und Druck im Erdinnern" in Gutenberg's ''Handbuch der Geophysik'' Bd.1, pp. 139–308, Berlin * 1949 Grundlagen der Höheren Geodäsie (

Erdmessung Geodesy ( ) is the Earth science of accurately measuring and understanding Earth's figure (geometric shape and size), orientation in space, and gravity. The field also incorporates studies of how these properties change over time and equivale ...

), Wien, Springer-Verlag.

External links

Österreich-Lexikon

F. Hopfner in der Deutschen Enzyklopädie

Ehrungen: Österreiche Geodätische Kommission, Friedrich Hopfner-Medaille

{{DEFAULTSORT:Hopfner, Friedrich 1881 births 1949 deaths Deaths by drowning Ludwig Maximilian University of Munich alumni Austrian geodesists 20th-century Austrian astronomers Accidental deaths in Austria Charles University alumni Academics of TU Wien German Bohemian people People from Trutnov