Athanasius Kircher was a 17th century German jesuit scholar who produced many publications on machinery. One of them, Musurgia Universalis, was written in 1650 and described ways of creating automatic music. The machine shown above, a water organ, is from Book 9 of that work. Water and air are introduced at the right side into a vessel termed a camera aeolis. The rate of water flow introduces a displacement of air which exits into the vertical pipes comprising the musical organ. The control of which notes are produced, and when, is achieved through barrel rotation. The water not only displaces air for the organ, but also drives the barrel. The barrel has protrusions that interact with the keys as the levers interact with the protrusions. There is a separate mechanism shown in the upper left of the illustration.