The piscina is very common in churches even where the sedilia or stone seats are wanting, and not only in the chancel, but also in the south walls at the east end of the north and south aisles, and in mortuary chapels, as will be presently noticed; it appears, in short, to have been an indispensable appendage to an altar. Sometimes the piscina is double, and contains two basins with drains, the one for receiving the water in which the hands had been washed, the other for the reception of the water with which the chalice was rinsed after the communion[189-*]. In Rothwell Church, Northamptonshire, on the south side of the chancel, are the vestiges of a triple piscina; the fenestella has been destroyed, but the three basins with their drains remain. Across the _fenestella_, or niche which contains the piscina, a shelf of stone or wood may be frequently found: this was the _credence_[190-*], or table on which the chalice, paten, ampullæ, and other things necessary for the celebration of mass were, before consecration, placed in a state of readiness on a clean linen cloth; and this originated from the πρόθεσις, or side table of preparation, used in the early church; a recurrence to which ancient and primitive custom by some of the divines of the Anglican church, after the Reformation, occasioned great offence to be taken by the Puritan seceders. In some instances a side table of stone or wood was used for this purpose; and a fine credence table of stone, the sides of which are covered with panelled compartments, is still remaining on the south side of the choir, St. Cross Church, near Winchester[190-†]. [Illustration: Ambrie or Locker, Chaddesden Church, Derbyshire.] The credence table, or shelf above the piscina, must not be confounded with the _ambrie_ or _locker_, a small square and plain recess usually contained in the east or north wall, near the altar. In this the chalice, paten, and other articles pertaining to the altar were kept when not in use. The wooden doors formerly affixed to these ambries have for the most part either fallen into decay or been removed, but traces of the hinges may be frequently perceived; and a locker in the north wall of the chancel of Aston Church, Northamptonshire, still retains the two-leaved wooden door. Sometimes shelves are set across the lockers. In the east wall of Earls Barton Church, Northamptonshire, is a large locker divided into two unequal parts by a stone shelf inserted in it; and in the north aisle of Salisbury Cathedral are two large triangular-headed lockers or ambries, each which[TN-6] contains two shelves.