Swedish-American inventor Henry Konrad Sandell designed this device, the Mills Violano Virtuoso. It's like a mechanical player piano, but it plays a violin. He patented it in 1905 along with Henry S. Mills of the Mills Novelty Company, a firm that made a wide variety of coin operated machines. Later designs added a piano in order to make the music more enjoyable than a solo violin could manage. Here's how the violin component functioned:
The strings are bowed by four small wheels made of discs of celluloid clamped together, applying just the right pressure to the strings. These are driven by a delicate variable speed controlled motor to vary the volume of sound produced. The vibrato is produced by shaking the tailpiece of the violin with a series of pneumatic pistons operated by a vacuum pump.
Some models had not just 1, but 2 violins. You can watch a video below of one of these Double Deluxe Violano Virtuosos.
-via The Presurfer