e curve on the _outside_ of the gable, exactly so much is
lost by curves on the _inside_. The natural tendency of such an arch to
dissolution by its own mere weight renders it a feature of detestable
ugliness, wherever it occurs on a large scale. It is eminently
characteristic of Tudor work, and it is the profile of the Chinese roof
(I say on a large scale, because this as well as all other capricious
arches, may be made secure by their masonry when small, but not
otherwise). Some allowable modifications of it will be noticed in the
chapter on Roofs.

[Illustration: Fig. XXXIII.]

Sec. XVII. There is only one more form of arch which we have to notice.
When the last described arch is used, not as the principal arrangement,
but as a mere heading to a common pointed arch, we have the form _c_,
Fig. XXXIII. Now this is better than the entirely reversed arch for two
reasons; first, less of the line is weakened by reversing; secondly, the
double curve has a very high aesthetic value, not existing in the mere
segments of circles. For these reasons arches of this kind are not only
admissible, but even of great desirableness, when their scale and
masonry render them secure, but above a certain scale they are
altogether barbarous; and, with the reversed Tudor arch, wantonly
employed, are the characteristics of the worst and meanest schools of
architecture, past or present.

This double curve is called the Ogee; it is the profile of many German
leaden roofs, of many Turkish domes (there more excusable, because
associated and in sympathy with exquisitely managed arches of the same
line in the walls below), of Tudor turrets, as in Henry the Seventh's
Chapel, and it is at the bottom or top of sundry other blunders all over
the world.

Sec. XVIII. The varieties of the ogee curve are infinite, as the reversed
portion of it may be engrafted on every other form of arch, horseshoe,
round, or pointed. Whatever is generally worthy of note in these
varieties, and in other arches of caprice, we shall best discover by
examining their masonry; for it is by their good masonry only that they
are rendered either stable or beautiful. To this question, then, let us
address ourselves.

CHAPTER XI.

THE ARCH MASONRY.

Sec. I. On the subject of the stability of arches, volumes have been
written and volumes more are required. The reader will not, therefore,
expect from me any very complete explanation of its conditions within
the lim