The hydraulic automaton of the “chirping birds” and of the “returning owl”

 An exceptional automatism of repetitive spectacle with motion and sound production.
It was a conception of Philon of Byzantium (which was improved by Heron of Alexandria) depicting birds chirping, when an owl turned away from them and they stopped frightened, when it turned towards them. Automatically, the theme was repeated continuously. For the operation of the automaton, water from a spring was driven inside the upper airtight container forcing the air to leave through a pipe. Because the pipe led to water, the vibrating wavelength produced a chirp with notes of different frequency. Then, when the water level exceeded the curved siphon of the container, it emptied through it to the intermediate container, diverting a yoke to its side. This forced the built-in rotating shaft supporting the owl to turn towards the birds that then stopped chirping. When the water level exceeded the axial siphon of the intermediate container, it emptied through to the lower container, diverting the yoke towards its counterweight, which caused the owl to turn away from the birds that then began to sing again, etc