>In your note you mentioned the piscina, as part of the medieval church.
>"Danmarks kirker", the ongoing inventory of Danish churches published by the
>National Museum in Denmark, includes the piscina in the inventory of the
>church.  Just for my own information, I checked 108 churches in Soroe Amt
>(County). Soroe Cathedral was built in 1160 by the Benedictines. There was
>one piscina and a possible second in that inventory. In only one other
>church in the county was the presence of a piscina noted. Since most of
>these churches were built 1100-1250, the question arises in my mind, when
>did the piscina become a liturgical requirement?

Since a piscina is a structural feature rather than a moveable possession, I
wonder if it would normally be included in an inventory?  You keep an
inventory as the record of the property of a church, lest anything be
mislaid or stolen;  but nobody could walk off with a piscina.

The liturgical washing of hands is the most ancient feature of the Christian
liturgy; indeed it is pre-Christian, going back to the Jewish Passover
celebration.  St Cyril of Jerusalem mentions it in the fourth century.
However, the priest does not need to use a piscina for the purpose;  it can
be done, as it originally was and is normally done now, with a pitcher of
water and a bowl, which the server can carry away and empty at his
convenience.  I quote from the article in the Oxford Dictionary of the
Christian Church:

"The piscina is of medieval origin;  in a few English parish churches and in
the crypt of Gloucester Cathedral, piscinas date back to the Norman period.
Sometimes two piscinas were set side by side, the one perhaps being reserved
for the washing of the priest's hands, the other for the cleansing of the
sacred vessels.  They are often richly decorated."