In 1829, the accordion was invented in Vienna, and it had spread to Switzerland by 1836. The accordion was popular because it was relatively easy to play and cheap to acquire, and took only one musician to play the melody and accompaniment. By the 1850s, the accordion was an integral part of Swiss folk music, and semi-professional ensembles were appearing to play at large social dances. Alongside the brass bands came string instruments like the violin and double bass; string bands soon began to displace the older brass bands. The accordion, however, did not make an appearance in these dance bands until about 1903, and it eventually replaced the two violins which had become standard.