c.,
and more of the Perp. period. The roof of Westminster Hall (Perp.,
erected 1397) shows how fine an architectural object such a roof may
become. The roof of the hall of Eltham Palace (Fig. 22) is another
good example. Wooden ceilings, often very rich, are not uncommon,
especially in the churches of Norfolk and Suffolk, but greater
interest attaches to the stone vaults with which the majority of
Gothic buildings were erected, than to any other description of
covering to the interiors of buildings.

The vault was a feature rarely absent from important churches, and the
structural requirements of the Gothic vault were among the most
influential of the elements which determined both the plan and the
section of a mediaeval church. There was a regular growth in Gothic
vaults. Those of the thirteenth century are comparatively simple;
those of the fourteenth are much richer and more elaborate, and often
involve very great structural difficulties. Those of the fifteenth are
more systematic, and consequently more simple in principle than the
ones which preceded them, but are such marvels of workmanship, and so
enriched by an infinity of parts, that they astonish the beholder,
and it appears, till the secret is known, impossible to imagine how
they can be made to stand.

[Illustration: FIG. 22.--ROOF OF HALL AT ELTHAM PALACE. (15TH
CENTURY.)]

It has been held by some very good authorities that the pointed arch
was first introduced into Gothic architecture to solve difficulties
which presented themselves in the vaulting. In all probability the
desire to give to everything, arches included, a more lofty appearance
and more slender proportions may have had as much to do with the
adoption of the pointed arch as any structural considerations, but
there can be no doubt that it was used for structural arches from the
very first, even when window heads and wall arcades were semicircular,
and that the introduction of it cleared the way for the use of stone
vaults of large span to a wonderful extent. It is not easy to explain
this without being more technical than is perhaps desirable in the
present volume, but the subject is one of too much importance for it
to be possible to avoid making the attempt.

Churches, it will be recollected, were commonly built with a wide nave
and narrower aisles, and it was in the Norman period customary to
vault the aisles and cover the nave with a ceiling. There was no
difficulty in so spac