§ 53. Wainscot partitions divided the dorter internally into a series of cubicles with a passage down the centre. Each cubicle was lighted by a window, and at Durham each contained a desk at which monks could work, if, as for example at the mid-day _siesta_ in summer, they were unable to go to sleep. This was the ordinary late arrangement: it is probable that in early monasteries the beds stood against the wall between the windows without any partitions. Although several monastic dorters are still roofed, as at Westminster and Durham, where they are in use as chapter libraries, at the Cistercian abbeys of Cleeve, Ford (where the dorter is now divided into many small rooms) and Valle Crucis, and at the Premonstratensian abbey of Beeleigh, the internal partitions have disappeared. At the further end of the dorter or at right angles to the further wall from the cloister, there was always a building known as _domus necessaria_, _necessarium_, or in English the rere-dorter, which was a long gallery with a row of seats against one wall, each lighted by a window and divided by a partition from the next. Beneath the seats was a drain or running stream, above which the partitions were carried by transverse arches: on the ground-floor the drain was shut off by a wall from the vaulted undercroft of the gallery. The _necessarium_ at Canterbury, known as the third dorter, was 145 feet long: it opened from the north-east corner of the great dorter, and was at right angles to the east wall, parallel to the second dorter, in which the obedientiaries or officers of the house slept. It contained 55 seats at first, 50 later. At Lewes the later _necessarium_, a separate building on lower ground than the dorter and connected with it by a bridge and stair, was 158 feet long and contained 66 seats. At Furness the _necessarium_ stood east of the dorter and parallel to it, with a two-storied building connecting the two. Here the seats were arranged back to back against a middle wall, with a passage at either side.