First performance of the reproduction Hydraulis Organ at Bath

Video

Alexander Henshaw plays the reproduction Roman Hydraulis, assisted by designer Richard Ellam. The apparently authentic tune is 'Aulos et Hydraulis' by German ensemble Musica Romana.
The water in the chamber holds back a smoothly-regulated reservoir of high pressure air to feed the pipes. The idea is to prevent the cyclical pulses from the bellows spoiling the steady notes of the organ, although a distinct 'beat' can be heard as the organ plays, made less obtrusive by Richard pumping in time with the music.
So - rather disappointingly - the water element doesn't actually help to create the pressure, which comes entirely from the 'manumatic' bellows on the back.