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magnetism, are presented in four pictures. Before the announce-
ment of his discovery (July 21, 1820) Oersted had been working
on and piepaiing his experiments keeping a journal o f his research
work. The latter was put before the six men after having been
thoroughly informed.
In 1820 Oersted formulated his discovery of electromagnetism,
a Nobel Prize Effect in modern terminology. A portrait o f Oer
sted made at that time is shown in a frontispiece. The voltaic bat-
tery which forms the background of the picture is made up some
of the 20 exterior copper electrodes which also serve as acid recei
ver to an interior zinc electrode in his direct current source. For
his discovery Oersted also made use of a wire connected to the
two terminals of the battery, and he gave an accurate description
of the various effects produced when this wire was held in various
ways in relation to the compass on the table in the right-hand side
of the picture.
Under the marking I-IV Oersted’s explanation of his discovery
is commented on in connection with his frontispiece portrait. H. C.
Oersted discovered piperin 1819 in Nørregade.
6
Other H. C. Oersted, publications, 1820.
On the very day o f Oersted’s Latin report (on 21’ July, 1820) he
issued two notices o f his discovery to the Danish press. They are
shown in facsimile.
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Pasteur’s and Håber s evaluation of Oersted’s discovery.
It has often been said that Oersted’s discovery was made “by acci
dent” . It would be more correct to say that the discovery was made
“unexpectedly” . Oersted did not work haphazardedly. He worked
extremely carefully and systematically. One has, however, to keep
a watchful eye on any unexpected possibility.
Professor Pasteur mentions this, and stresses the importance of
being able to snatch and catch “the unexpected” , and he points to
Oersted’s discovery as an example, in his inaugural leeture at “La
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