Paul Melchior was born in September 1925 in Mont-sur-Marchienne (Charleroi) and died on 15 September 2004 following complications arising after a hip operation. During his lifetime, Baron Paul Melchior was considered the specialist in the phenomenon of earth tides and questions concerning the earth's rotation. (1) He was co-founder of the Underground Laboratory for Geodynamics in Walferdange (LSGW), which enabled research into geophysics to be developed and expanded in the Grand Duchy of Luxembourg, and a room at the LSGW was officially named the "Laboratory for Absolute Gravimetry, Baron Paul Melchior" on 21 June 2007.

Situated in the side tunnel of a gypsum mine, the LSGW is currently managed by scientists from the European Centre for Geodynamics and Seismology (ECGS) (2). Its principal objective is to develop European cooperation in the realm of scientific research into geodynamics and seismology, applied to the prevention of natural disasters. Now of world renown, the LSGW reflects the truly remarkable character of one of its founders, Baron Paul Melchior.

Stages of a life dedicated to research and publication

Having undertaken his military service at the Institut Géographique Militaire, Paul Melchior took up a post as assistant at the Royal Observatory of Belgium in Brussels-Uccle in 1949. Two years later, he gained a doctorate in mathematical sciences at the Free University of Brussels with the highest possible distinction.

During his long professional career, Paul Melchior was head of the Meridian and Geodynamic Astronomy Department at the Royal Observatory of Belgium from 1969 to 1981, then Director of the Observatory from 1984 to 1990. He was Professor at the Catholic University of Louvain from 1972 to 1990, and he also held the following posts: Secretary-General of the International Union of Geodesy and Geophysics from 1973 to 1991, Director of the International Centre for Earth Tides from 1958 to 1995, President of Commission 19 (Earth Rotation) of the International Astronomical Union from 1967 to 1970, and President of CODATA (Committee on Data for Science and Technology) from 1974 to 1978. Although very busy in his numerous positions, Paul Melchior directed or contributed to the publication of around 300 articles, plus a series of books in French on physics and planetary dynamics, as well as 3 monographs in English. The 1st, which appeared in 1978, was dedicated to earth tides, and still remains the only complete book on the subject.

This unparalleled scientific career was accompanied by numerous honorary and academic distinctions from Belgium and other countries. Besides the title of Baron, which was conferred upon him by Belgian King Baudouin I st in 1993, his election as Fellow of the American Geophysical Union in 1979 stands out, an honour rarely given to a European national. Among other distinctions are his nomination as honorary professor of the Institute of Geodesy and Geophysics at the Chinese Sinica Academy, his nomination as foreign member of the Finnish Academies of Sciences and Arts in 1974, the Spanish Royal Academy of Sciences in 1985, the Dutch Royal Academy of Sciences in 1988 and the Romanian Academy of Sciences in 1992. Five years later, he became the 1 st medal holder of the Commission of Earth Tides.

Exceptional work on stars and tides

Beginning his career as an astronomer, Paul Melchior spent long nights observing at the Askania Great Meridian Circle in Brussels-Uccle between 1950 and 1957. This led to the publication of the most precise catalogue of stars of its time in 1966. He had meanwhile become interested in the earth's rotation, and developed a complete theory of the movements of the earth's rotational axis and the link between these movements and earth tides. As a result, he began measuring earth tides using quartz Verbaandert-Melchior tiltmeters (instruments used for measuring angles in relation to the line of the horizon) from 1957. While studying earth tides, Paul Melchior was also involved in gravimetry. His skills in the field were such that, in 1973, the US Air Force allocated him a substantial proportion of the funds needed to develop a global gravimetric profile.

Over 20 years or so, 127 stations were established throughout the world. Their observations enabled refinement of the oceanic models for all the oceans which, under the influence of the tides, contribute to deformation of the earth's crust.

Station at Walferdange in collaboration with Johnny Flick

In 1962, Professor Melchior contacted the Luxembourg Minister for Arts and Sciences, Pierre Grégoire, regarding the possibility of installing a gravimeter in Luxembourg. In 1963, Paul Melchior and Luxembourg engineer Jean ("Johnny") Flick set up Luxembourg's 1st geophysics station in the blockhouses of Saint-Esprit (Kanounenhiwel) in the City of Luxembourg. In view of the challenges posed by a scientific research station, the 2 scientists were quickly forced to leave these premises in order to set up the Underground Laboratory for Geodynamics in Walferdange in 1968. Equipped with 2 high-tech instruments – an absolute gravimeter and a supraconducting gravimeter – the LSGW is today one of the world's leading centres for precision gravimetry.

In a bid to promote cooperation between scientists working within the various disciplines of geodynamics, Paul Melchior, Johnny Flick and French astronomer François Barlier created the Journées Luxembourgeoises de Géodynamique (JLG) in 1970, of which Paul Melchior was the 1st president. Very soon, numerous figures from the scientific arena in various countries were attending and contributing to the event. Later, when Paul Melchior co-founded the ECGS in 1988, it led to new scientific and educational activities, such as international workshops. In this way, the Grand Duchy has remained a centre for debating and refining theoretical views and experimental results in the field of geodynamics.

Text: © Christophe Knebeler, WORT

Photo: © Tessy Hansen

Photo: A scientist is honoured: Just a few days before National Day in Luxembourg 2007, a room at the Underground Laboratory for Geodynamics in Walferdange is named after Baron Melchior.

(1) Besides the domains of seismology and magnetism, geophysics (internal), includes the branches of gravimetry and geodesy. Gravimetry is the science of measuring and studying gravity, i.e. the acceleration which a body undergoes when falling to the earth's surface, while geodesy is the science which aims to determine the form of the earth, the measurement of its dimensions and the preparation of maps.

(2) Geodynamics is the study of natural events to which our planet is subject.