H. C.

1
H. C. Ørsted (1777-1851)
Highlights of Ørsteds Life and Pioneering Works
Prologue. Hans Christian Ørsted was born on 14
August 1777 in Rudkøbing, a small city at the
small Danish island Langeland. He was the first
of 8 children of the chemist Søren Ørsted and his
wife Karen. Hans Christian in 1797 passed the
final University examination for the
pharmaceutical degree and only 2 years later he
became doctor of philosophy on a thesis with the
title Basic features of the metaphysics in
nature. Earlier, in 1798, he had earned a gold
medal reward from Copenhagen University for a
dissertation on The origin and benefit of
amniotic fluid. In 1800 he started as lecturer
in physics at the University.
Foundation of Danish Technical University Through
the initiative from H.C. Ørsted the Polytechnical
High School (Technical University) was founded in
1829. He became its first director. In the
charter for the institution the first article
reads 1.The Polytechnical High School opens
for all estates the access to education and
excercise in mathemathics and experimental
natural sciences with paricular emphasis on
applications. Here he conducted many physics
experiments for the students and constructed a
range of elaborate instruments.
Travels around in Europe. In 1801-04 Hans
Christian Ørsted traveled to Germany (Berlin) and
France (Paris) and established profound contact
with the european scientific communities. He was
strongly influenced by the romantic philosophy
and developments in natural sciences at that
time. At his return to Copenhagen he continued
teaching and was in 1806 appointed extraordinary
professor at Copenhagen University. In these
years he was strongly inspired by the appearance
of sonorous (Chladni) figures formed in fine
grane dispersed at a plate stroken by the bow.
Such experiments whereby musical tones were
converted into stringent mathematical shapes
indicated to Ørsted the beauty and unity in
nature and science and gave inspiration to some
of his significant philosophical works.
H. C. Ørsted and J. C. F. Gauss In 1834 H.C.
Ørsted visited J. C. F.Gauss (1777-1855) in
Göttingen and studied the geomagnetic instruments
and the measuring methods developed there. Among
other he noted an instrument consisting of a
heavy (4 pound) magnet bar suspended in a silk
wire. At the magnet bar was mounted a mirror
which in combination with a light beam and a
distant display will allow for sensitive
detection of attitude changes.
First geomagnetic observations Upon his return
he had made a geomagnetic observatory with
similar instrumentation at the Polytechnical High
School and used students to regularly observe the
deflections. Through comparison of simultaneous
recordings made in Copenhagen and Milano (at 1100
kms distance) he discovered that during a
magnetic storm the deflections at these widely
separated sites had the same appearance. This
observation was published in Magnetiske
Iagttagelser i Kjøbenhavn. (1834-35)
Inspiration from Germany and France. H.C. Ørsted
was also strongly interested in physics and
chemistry. In 1812-13 he again made a study
excursion to Germany and France and was deeply
impressed by the new trends in experimental
physics which were developing there, particularly
at the Polytechnical Universities in France.
During the stay in Germany he issued a
dissertation Ansicht der chemischen
Naturgesetze. (Berlin 1812) which caused strong
attention in the scientific community. In France
he published his ideas in Recherches sur
lidentité des forces chimiques et électriques
(Paris 1813). Two essential theories were
forwarded in this work. One was a postulate that
electricity can generate magnetism the other was
a postulate that light is electrical
oscillations. Both were revolutionary and in
strong contrast to the commonly agreed Laplacian
concept that light, heat, electricity, and
magnetism were different independent agents. At
this time Ørsted had no experimental evidence to
support the hypotheses.
Routine Geomagnetic observations In 1842, on H.C.
Ørsteds initiative a geomagnetic observatory was
built at Gyldenløves Bastion, one of the
fortresses in the fortification of Copenhagen.
Routine observations of the magnetic declination
and field strength were performed from this
location through more than 20 years. The
observations were moved to Rosenborg Bastion in
1862 but then they ceased and were stopped for
some years. In 1889 a new magnetic observatory
was built by the Danish Meteorological Institute
and the routine geomagnetic observations were
resumed by DMI in 1891 to continue the work
initiated by H.C. Ørsted.
Aurora and magnetism Auroras are occasionally
observed from Denmark. During the first solar
maximum in 1705-06 following the extended Maunder
minimum around 1600-1700 a number of large
magnetic storms occurred during which auroras
were observed from Copenhagen. Drawings of the
aurora were made by the Danish astronomer Ole
Rømer (1640-1710). Later in the century Olof
Peter Hiorter (1696-1750) observed the relations
between active auroral displays and geomagnetic
disturbances. The connection between aurora and
magnetism was further substantiated by the works
of Christopher Hansteen (1784-1873), professor at
the University of Christiania (Oslo), Norway.
Discovery of Electromagnetism. In April 1820
during a lecture given to students at the
University of Copenhagen Ørsted observed the
effect from electric currents in a wire on a
compas needle. In June 1820, 3 months later, he
repeated the experiment in presence of official
vitnesses. When the electric current in a wire
held over a compas needle was turned on then the
needle was deflected to the side. The
electromagnetic effect was discovered. H.C.
Ørsted published his observation in the paper
Experimenta circa effectum conflictus electrici
in acum magneticam. (Hafniæ 1820).
Ørsteds Compass
Ørsteds Contribution to Auroral Research H.C.
Ørsted was interested in auroras and aware of the
magnetic effects from aurora. He suggested in
1824 that the magnetic variations observed during
auroras could be caused by electrical currents in
the upper atmosphere along the auroral curtains.
His theory, which at that time was revolutionary,
was published in Bemærkninger over Nordlysets
Theorie (1823-24) Reflections over the theory
of auroras
Aurora observed over Copenhagen on 1 February
1707. Drawing by Ole Rømer.
H.C. Ørsted and Meteorology Ørsted had a profound
interest in Meteorology. In 1827 the Danish Royal
Society for Science and Letters, on Ørsteds
initiative, founded a permanent Meteorological
Committee. The Committee encouraged
meteorological sciences and initiated
meteorological observations at various places in
Denmark and in the Danish oversea colonial
territories. H. C. Ørsted issued several
publications on meteorological topics, among
other, Over Skypompen (Copenhagen, 1836)
Above the waterspout.
Ørsteds Barometer and Thermometer
Ørsteds setup to demonstrate the magnetic effect
of electric currents
H.C. Ørsted Painting A painting of Ørsted made by
the renowned Danish painter Eckersberg now
resides at the National Museum at Frederiksborg
Castle in Hillerød. In the painting is included
reference to some of the most important
accomplishments by H.C. Ørsted. In the foreground
to the right is seen a compass with an electrical
wire stretched across it. At the table to the
left is seen a plate with sonorous figures. In
the background is seen the instrument used for
compressional experiments and some chemists
tubings. The globe may symbolise Ørsteds interest
in geography and geomagnetism and his many
travels to other European countries. The pile of
books just behind his arm may signal his immense
scientific publication activity. It is worth
noting that H.C. Ørsted mastered German, French,
English and Latin (in addition to Danish) and
wrote his many publications in any of this
variety of languages.
Important Experimental Works H.C.Ørsted conducted
many experiments to study the chemical and
physical nature of various elements and
compounds. He studied the compressibility of
fluids and gases through a series of
comprehensive and accurate experiments published
e.g. in Ueber die Zusammendrückung des Wassers.
(Copenhagen 1817), On the relative
compressibilities of different fluids at high
temperatures (1827) Ørsted studied the
electricity from galvanic elements, e.g.
Versuch über Zambonis zweigliedrige galvanische
Kette (Copenhagen 1821), and thermoelectricity,
e.g., Thermo-electricity. (Copenhagen 1830)
In 1925 he produced the worlds first sample of
Aluminium metal from Alumina (Clay soil) and
published his results in Vorläufige Notiz über
die Darstellung des Argillium, des
Chlor-Argillium und Chlor-Silicium. (Copenhagen
1825)
Ørsteds Piezometer
Peter Stauning. Danish Meteorological Institute.
September 2002. pst_at_dmi.dk