Turning back towards the infirmary entrance we come to #the Lavatory Tower#, which stands out from the west end of the substructure of the Prior's Chapel. The chapel itself was pulled down at the close of the seventeenth century, and a brick-built library was erected on its site. The lavatory tower is now more commonly called the baptistery, but this name gives a false impression, and only came into use because the building now contains a font, given to the cathedral by Bishop Warner. The lower part of the tower is late Norman in style, and was built in the latter half of the twelfth century, when the monastery was supplied with a system of works by which water was drawn from some distant springs, which still supply the cathedral and precincts. The water was distributed from this tower to the various buildings. The original designs of the engineer are preserved at Trinity College, Cambridge. The upper part of the tower was rebuilt by Prior Chillenden. From the lavatory tower a covered passage leads into the great cloister, which can also be approached from a door in the north-west transept. The cloister, though it stands upon the space covered by that built by Lanfranc, is largely the work of the indefatigable Prior Chillenden. It shows traces of many architectural periods. The east walk contains a door, leading into the transept, embellished with a triple arcade of early English; under the central arch of the arcade is the doorway itself, a later addition in Perpendicular. There is also a Norman doorway which once communicated with the monks' dormitory: after the Reformation it was walled up, but in 1813 the plaster which concealed it was taken away, and since then it has been carefully restored. The rest of the work in this part of the cloister is chiefly Perpendicular. The north walk is adorned with an Early English arcade, against which the shafts which support Chillenden's vaulting work are placed with rather unsatisfactory effect. Towards the western end of this walk is the door of the refectory. [Illustration: TURRET OF SOUTH-WEST TRANSEPT.] The cellarer's quarters were outside the west walk, and they were connected with the cloister by a doorway at the north-west corner: opposite this entrance was a door leading to the archbishop's palace, and through this Becket made his way towards the cathedral when his murderers were in pursuit of him.