[Illustration: Fig. 353.--Interior of the Chapter-house, Westminster
Abbey.]
there is a choice between two methods of effecting it: either by
supposing the main vault to span from _wall to pillar_ or from _angle to
pillar_ (Figs. 351, 352).
The former is, on a _primâ facie_ view, the more natural, but it has the
disadvantages of breaking the chief side of the vaulting compartment
which rises from the corners into a resalient angle, and also of
rendering the main ribs from these angles across to the pillar, in one
half of their length _diagonal_ ribs, and in the other _transverse_; and
of making one half represent a _projecting_ and the other a _receding_
angle, while the _angle_ ribs of the outer half meet the _transverse_
ribs of the inner half of the vault.
These objections are entirely removed by supposing the main vaults to
run directly from the angle to the pillar. In either case the ridge
which surrounds that half of the vault which springs from the pillar
takes the form of an inner octagon.
In the first case, the sides of this are parallel to the walls, while in
the second they take an intermediate direction; the angles of the inner
octagon being opposite the centres of the sides of the outer one, and
_vice versâ_.
The vaulting compartments which rise from the angles of the great
octagon are precisely similar to the opposite ones which rise from the
pillar, and the ribs which rise from the angles to the pillar are
throughout _transverse_ ribs, while the angle ribs from each side duly
meet one another.
I exhibit a view of the interior of the Chapter-house, Westminster (Fig.
353), to show the beauty of this form of vaulting. Few forms, in fact,
in any style of architecture present such beauties as an octagon
vaulted in this manner; and I am happy to think that our London
specimen, which has been lost for the last century or more, will now
very shortly be restored to its original form and condition.
I have already mentioned that in all these forms of vaulting,--that is
to say, those with level ridges,--owing to a geometrical error resulting
from the use of circular curves for all the ribs, the filling in of the
vaulted spaces must be artificially shaped to fit those curves.
The use, however, of a form of vaulting analogous to that before
described as having _raised_ ridges would obviate this inaccuracy.
Suppose, for example, an oblong compartment with pointed arches of
similar proportions on all its sides and on its diagonals, and the
vaults of each cell generated by the motion of the curve of the
surrounding arches towards the point of intersection, guided by the
diagonals, we obtain at once a vault with pointed arches and raised
ridges, the precise correlative of that before described with round
arches and raised ridges, and one in which the filling of the vaulted
spaces assumes a systematic and accurately geometrical form (Fig. 354).
[Illustration: Fig. 354.]
The proportions of the arches are not essentials, but where the narrower
arches approach the height of the wider ones, a curious effect is
produced on the form of the ridge, which, always elliptical, becomes
then so obviously so as to be unpleasing.
This form of vault was of very frequent use, though the exact method of
filling in the spaces was not rigidly adhered to. Its disadvantages are,
that it either limits the height of the walls available for windows, or
runs up so high into the roof as to interfere with its construction. It
is in many cases, however, a very convenient, as it is a very sightly,
form of vaulting.
Even the simple form of vaulting with level ridges is not always
convenient for windows, particularly in clerestories, where they have
often to fill the whole space. This led to the practice of stilting the
wall-rib to such a degree, as to have the effect of twisting the groined
surface of the cross vault to an extraordinary extent. This may be seen
in the vaulting of the cells adjoining the clerestory at Westminster
Abbey, and at St. Saviour’s, Southwark (Fig. 355). This twisting of the
surface has received the very appropriate name of _ploughshare_
vaulting.
[Illustration: Fig. 355.--St. Saviour’s, Southwark. Vaulting of cells
adjoining the clerestory.]
The liberty which was felt in dealing with the surfaces of
vaulting-spaces, when once the salient lines became emphasised by ribs,
led to the practice of the “doming up,” as it is called, of those
spaces, whether the ridges were raised or level; that is to say, that
each course of the filling-in stonework was often laid on a curve, so as
to increase the strength of the work, by rendering every course a kind
of arch from rib to rib.
I must, however, reserve to my next lecture a description of many of the
forms which the vaulting of this period assumed, and a number of
practical facts relating to it; as well as the pursuit of the subject
into its more advanced history; where, instead of limiting its features
to such as originated in obvious and functional utility, others were
added for purely decorative purposes. The subject is so extensive that I
am compelled to divide my lecture upon it abruptly.
Let us, then, pause here and consider for a moment the artistic
sentiment and character of the stage at which we have arrived. I will
suggest, in passing, that this stage, in which no architectural features
were introduced for mere purposes of decoration, and which consequently
leaves wide vaulting-spaces, is peculiarly suited to the extensive
introduction of the works of the sister arts of painting and mosaic,
which may be used almost as freely here as in the Byzantine domes. The
point to which, however, I desire to direct your attention is rather the
_purely architectural_ sentiment.
Small as is the difference of principle between the later Norman
vaulting and that under consideration, the impression produced upon the
mind is entirely changed. The one suggests weight and pressure
systematically met and resisted; in the other those forces appear to
have vanished; and the effect suggested is rather a shooting boldly
upwards, like the growth of a tree, than any downward pressure towards
the earth. True it is that, in the decorative treatment, a colonnette is
placed under every rib or group of ribs as its artistic support; yet, in
its effect upon the imagination, the action is reversed. It is not the
column bearing the weight of the arched ribs, but the latter springing
vigorously upward from the column.
Who, while viewing a stately tree in the pride of its growth, ever
thinks of its _weight_, or of the pressure of its boughs upon the stem?
It is with its _upward soaring_ that the mind becomes impressed; and
just so it is with the interior of a Gothic cathedral. The perfection
with which all physical forces are met has to the mind the effect, not
merely of having annihilated, but of having actually _reversed_ them. So
that upward striving, stately growth, and heavenward aspiration are the
ideas customarily suggested as illustrating the impressions produced.
The lofty avenue, with its intersecting branches, has become the chosen
similitude to which it is popularly likened, and it has been universally
received as the form of architecture most expressive of the heavenward
soarings of our religion.
No one who contemplates our glorious Abbey Church of Westminster, and
lays his soul open to its inspiration, can fail to feel sentiments in
harmony with those suggested by the cognisance of its saintly
founder--selected as if in anticipation of its future glories--the
symbol of our religion surrounded by martlets, whose feet are erased in
token that they have lost all tendency to rest on earth, but, like the
aspirations of Christian worship, ever mounting on the wing towards the
supreme object of adoration, and
“Flying up to Heaven gate ascend,
Bear on their wings and in their notes His praise.”