ERSE SECTION OF THE NAVE OF SALISBURY
CATHEDRAL. (A.D. 1217).]

The arrangement and construction of a Gothic cathedral were
customarily as follows:--(See Fig. 2.) The main axis of the building
was always east and west, the principal entrance being at the west
end, usually under a grand porch or portal, and the high altar stood
at the east end. The plan (or main floor) of the building almost
always displays the form of a cross. The stem of the cross is the part
from the west entrance to the crossing, and is called the nave. The
arms of the cross are called transepts, and point respectively north
and south. Their crossing with the nave is often called the
intersection. The remaining arm, which prolongs the stem eastwards, is
ordinarily called the choir, but sometimes the presbytery, and
sometimes the chancel. All these names really refer to the position of
the internal fittings of the church, and it is often more accurate
simply to employ the term eastern arm for this portion of a church.

The nave is flanked by two avenues running parallel to it, narrower
and lower than itself, called aisles. They are separated from it by
rows of columns or piers, connected together by arches. Thus the nave
has an arcade on each side of it, and each aisle has an arcade on one
side, and a main external wall on the other. The aisle walls are
usually pierced by windows. The arches of the arcade carry walls which
rise above the roofs of the aisles, and light the nave. These walls
are usually subdivided internally into two heights or stories; the
lower story consists of a series of small arches, to which the name of
triforium is given. This arcade usually opens into the dark space
above the ceiling or vault of the aisle, and hence it is sometimes
called the blind story. The upper story is the range of windows
already alluded to as lighting the nave, and is called the clerestory.
Thus a spectator standing in the nave, and looking towards the side
(Figs. 4 and 5), will see opposite him the main arcade, and over that
the triforium, and over that the clerestory, crowned by the nave vault
or roof; and looking through the arches of the nave arcade, he will
see the side windows of the aisle. Above the clerestory of the nave,
and the side windows of the aisles, come the vaults or roofs. In some
instances double aisles (two on each side) have been employed.

The transepts usually consist of well-marked limbs, divided like the
nave into a cent