Hi all,  The argument about ancient water organs is very fascinating.
I was struck by the water organ since the first times that I devoted
my attention to pipe organs; my logo, indeed, represents an ancient
hydraulis taken from a bas-relief of an ancient Roman sarcophagus.

I am aware of three attempts of rebuilding a hydraulic organ.  The
description of the first of them, by Rev. F.W. Galpin, can be found at
http://users.ipa.net/~tanker/organs.htm , and that description is all
that I know of, as I never found further details.

The second attempt is reported in the book, "The Organ from Its
Invention in the Hellenistic Period to the End of the Thirteenth
Century", by Jean Perrot, originally published in France in 1965,
translated from the French by Norma Deane, Oxford Univ. Press, 1971.

The book is a comprehensive collection of all literary and
archaeological evidence about the argument, with comments and
descriptions of ancient musical systems and scales.  Quite a nice
book, and still up-to-date, as almost no significantly new item has
been published later, as far as I know.  Among the other things,
the author describes, with many details, his attempt to rebuild an
hydraulis.  I don't know where the instrument is currently located.

The remains of an ancient organ, dated around 280 AD, were found at
Aquincum, near Bucharest, Hungary, in 1931, but the organ was probably
fed by bellows, as no bronze cistern was found.  It was badly
"restored" in the 1960's and is now shown in Aquincum's Museum.

An apparently faithful copy has been made by the Hungarian organ
builder Pecs; see http://www.orgona.hu/orgonaink/tuzolto_orgona_e.html
It has been made with a water wind supply system, which, although
apparently well made, is not consistent with the evidence of the
findings.  I don't know how it sounds.

As to the instruments size, according to the images in ancient
sculptures and mosaics, it appears to be very small-sized, the total
height slightly exceeding that of a person.  If you like, I could send
some scanned images.

According to the ancient writers, the sound generated by the hydraulic
organ was very loud, something like modern calliopes, so I believe
Robbie and other calliope lovers would have liked it very much.

The hydraulis was used mainly in the mundane "spectacula" in arenas,
but then it was disliked by the Fathers of the Christianity in the
early centuries.  Only in the course of the Middle Ages the organ
became the instrument of the church.

Best regards

Leonardo Perretti