The end arcade, abutting on the church proper, was used by penitents and called the _narthex_. The body of the church was divided, as in the basilica halls, into central nave and side aisles--the latter sometimes double. Across the end of the nave extended the _bema_ or sanctuary, corresponding to the space raised and enclosed for litigants and lawyers in the basilica. Its ends projected beyond the line of the main building, forming rudimentary transepts, which may have been used as sacristies for the robing of the clergy and the preservation of the sacred vessels and other ritual objects. The central part of the bema was elevated and occupied by the altar which was surmounted by a _baldachino_ or canopy, supported on four columns. Behind the altar was the apse, lined with seats; those of the Roman assessors being now occupied by the presbyters, while the centre one of the quæster or praetor became the bishop’s throne. For the transference of the latter to the side of the choir was of later date. The officiating priest stood behind the altar, facing the congregation and the east. For as yet the main façade was not the western, a fact of interest when we recall that while the Hellenic architects built facing the four points of the compass and made the chief entrance on the east, the Romans were indifferent to the matter of orientation. In certain instances as that of =S. Clemente=, in =Rome=, the accommodation for the choir projected from the bema into the nave. It was enclosed with low screen walls called _Cancelli_ (whence was derived the word chancel); the side walls projecting to afford space for two reading desks, or _ambones_; respectively, the Gospel _ambo_ and the Epistle _ambo_. =Treatment of Columns.=--There were two ways of treating the columns. In the earlier type of churches, the aisles were spanned by arches, while those of the nave supported an entablature. But this necessitated a narrow intercolumniation, considerably obstructing the view. Accordingly, the practice ensued of placing the columns further apart and surmounting them with arches. The first example of this use of _arcades_ in a nave is believed to occur in the northern gallery of the =Palace of Diocletian= in =Spalato, Dalmatia=. Both methods continued to be employed and were sometimes combined in the same building. Over the entablature or arches, as the case might be, was a high stretch of wall, rising above the level of the aisle roof, pierced with a row of _clerestory_ windows. The nave and aisles terminated in arches, that of the former, the principal entrance to the sanctuary, being called the Arch of Triumph. The roofs were of timber; that of the nave rising to a ridge and finishing at each end in a gable, while a slope from below the clerestory covered the side aisles. The construction work of the roofs was usually hidden in the interior by flat ceilings, beamed and coffered.