After his revolutionary discovery of electromagnetism in 1820 H.C. Oersted quickly published his findings in a small treatise in Latin for the scholars of Europe. Soon after the treatise was translated into French, Italian, German, English and Danish, and reprinted in a number of scientific journals. This new publication contains photographic reproductions of all these texts. Søren Absalon Larsen, professor at the College of Advanced Technology founded by Oersted in 1829, currently DTU (Technical University of Denmark) published the texts in facsimile in 1920, the hundred-year anniversary for Oersteds discovery. It is this 1920 edition which is now reprinted, supplemented by a new postscript by Carl Henrik Koch.