Piscina in Morning Chapel, Lincoln Cathedral
A piscina is a shallow basin usually located in an architectural niche of a church. It is used by the priest to wash his hands before celebration of the eucharist and for washing the chalice after the celebration. More often located in the sacristy than in the sanctuary.
William Dwight Whitney, PhD, LLD The Century Dictionary and Cyclopedia (New York, New York: The Century Co, 1902) 4510