Water Organ - Mechanics

Mechanics

Typically, water is supplied from some height above the instrument through a pipe, and air is introduced into the water stream by aspiration (using the Bernoulli effect) into the main pipe from a side-pipe holding its top above the water source. Both water and air arrive together in the camera aeolis (wind chamber). Here, water and air separate and the compressed air is driven into a wind-trunk on top of the camera aeolis, to blow the organ pipes. Two perforated ‘splash plates’ or ‘diaphragms’ prevent water spray from getting into the organ pipes.

The water, having been separated from the air, leaves the camera aeolis at the same rate as it enters. It then drives a water wheel, which in turn drives the musical cylinder and the movements attached. To start the organ, the tap above the entry pipe is turned on and, given a continuous flow of water, the organ plays until the tap is closed again.

Many water organs had simple water-pressure regulating devices. At the Palazzo del Quirinale, the water flows from a hilltop spring (once abundant, now only sufficient to play the organ for about 30 minutes at a time), coursing through the palace itself into a stabilizing ‘room’ some 18 metres above the camera aeolis in the organ grotto. This drop provides sufficient wind to power the restored six-stop instrument.

Among Renaissance writers on the water organ, Salomon de Caus was particularly informative. His book of 1615 includes a short treatise on making water organs, advice on tuning and registration, and many fine engravings showing the instruments, their mechanisms and scenes in which they were used. It also includes an example of suitable music for water organ, the madrigal Chi farà fed' al cielo by Alessandro Striggio, arranged by Peter Philips.