Two Sirens Circa 1850-1880. In perfect working condition. It comprises a small air-chest at bottom with an oblique-perforated rotor and worm drive above. When air from a bellows is forced into the bottom, it blows out from a series of oblique several holes in the top of the air chest. These holes coincide with others in the rotor and cause it to rotate at high velocity, emiting and very loud wailing sound. By sliding the headgear to one side causes the worm on the rotor to engage with a pinion which in turn on the dials to revolve, indicating the speed of rotation. Measurements: 15 cm by 12 cm and the one with the rules 23 cm high by 12 cm ( the wooden base isn’t original
