The sacristy (or vestry) adjoined the south
transept of the church. A stair in the south wall of the transept
led to two small rooms, with the library on the west and the sacristy
on the east. Liturgical vessels, vestments and books used in the
Mass and Canonical
Offices were stored for safekeeping in the sacristy,
under the watchful eye of the sacrist. The sacristy was also used
by ordained members of the community to robe in vestments for services,
and it was thus necessary that this room was close to the church.