Cyrill Demian (1772–1847) made his living as an organ and piano maker, with his two sons Karl and Guido, in Mariahilfer Straße No. 43 in Vienna, Austria. On May 6, 1829, Cyrill and his two sons presented a new instrument to the authorities for patent - the accordion. The patent was officially granted on May 23, 1829.
Read more about Cyrill Demian: Modern References, Demian's Accordion Description, The First Accordion Debate, The Accordion Assembly