A. The general ground plan of cathedral and conventual churches was after the form of a cross, and the edifice consisted of a central tower, with transepts running north and south; westward of the tower was the nave or main body of the structure, with lateral aisles; and the west front contained the principal entrance, and was often flanked by towers. Eastward of the central tower was the choir, where the principal service was performed, with aisles on each side, and beyond this was the lady chapel. Sometimes the design also comprehended other chapels. On the north or south side was the chapter house, in early times quadrangular, but afterwards octagonal in plan; and on the same side, in most instances, though not always, were the cloisters, which communicated immediately with the church, and surrounded a quadrangular court. The chapter house and cloisters we still find remaining as adjuncts to most cathedral churches, though the conventual buildings of a domestic nature, with which the cloisters formerly also communicated, have generally been destroyed. Mere parochial churches have commonly a tower at the west end, a nave with lateral aisles, and a chancel. Some churches have transepts; and small side chapels or additional aisles have been annexed to many, erected at the costs of individuals, to serve for burial and as chantries. The smallest class of churches have a nave and chancel only, with a small bell-turret formed of wooden shingles, or an open arch of stonework, appearing above the roof at the west end. [Illustration: SEDILIA, St. Martin’s, Leicester, circa A. D. 1250.] CHAPTER II. OF THE DIFFERENT KINDS OF ARCHES. Q. Do the distinctions of the different styles, as they differ from each other, depend at all upon the form of the arch? A. To a certain extent the form of the arch may be considered as a criterion of style; too much dependence, however, must not be placed on this rule, inasmuch as there are many exceptions. Q. How are arches divided generally, as to form? A. Into the triangular-headed or straight-lined pointed arch, the round-headed arch, and the curved-pointed arch; and the latter are again subdivided. Q. How is the triangular-headed or straight-lined pointed arch formed, and when did it prevail? A. It may be described as formed by the two upper sides of a triangle, more or less obtuse or acute. It is generally considered as one of the characteristics of the Anglo-Saxon style, where it is often to be met with of plain and rude construction. But instances of this form of arch, though they are not frequent, are to be met with in the Norman and subsequent styles. Arches, however, of this description, of late date, may be generally known by some moulding or other feature peculiar to the style in which it is used. [Illustration] Q. What different kinds of round-headed arches are there? A. The semicircular arch (fig. 1), the stilted arch (fig. 2), the segmental arch (fig. 3), and the horse-shoe arch (fig. 4).