oersted's announcement, 21st July, 1820.
© Science Museum / Science & Society Picture Library
Pamphlet written by the Danish physicist Hans Christian oersted (1777-1851), announcing his discovery of electromagnetism (the interaction between electricity and magnetism). According to oersted's own account, the discovery of electromagnetism occured whilst he was conducting a lecture in the spring of 1820. The results of his discovery were published (first in Latin) later the same year, on 21st July 1820. oersted's findings were widely read throughout Europe, and led to Andre Marie Ampere developing electrodynamics.