is the curve which mathematicians call the curve of contra-flexure, and which is known amongst architecturalists as the Ogee.

WILSFORD.

The flowing nature of this curve imparted to the Tracery a grace and an ease which the rigid outline of the Circle denied it: and affords us a strong point of contrast whereby to distinguish the Architecture of the two Periods. The sinuosity of form which characterises the tracery, pervades also the mouldings, the carved work, and all the details of this Period, and enables us to designate it appropriately as the CURVILINEAR PERIOD.

WINCHESTER.

In the latter part of this Period, a horizontal bar, or transom, as it is called, was occasionally used in the lower part of the window. Whether this bar was introduced for the purpose of strengthening the mullions, or for the sake of proportion, it speedily grew into frequent use. At the same time also vertical lines presented themselves occasionally in the Tracery; a new principle, in fact, had made its appearance, which rapidly overran not only the windows, but the doorways, the arcades, and every part of the building. The straight line, when once introduced, quickly superseded the curved line; square panels covered the walls; angularity of form pervaded even the mouldings and minor details, and to the round finish, the square edge was preferred.

This, the last of the four Periods of Gothic Architecture which extended over a term of nearly two Centuries, we propose accordingly to call the RECTILINEAR PERIOD.

The History of our National Architecture will thus be divided into Seven Periods, the order and duration of which are as follows:—

INTERIOR COMPARTMENT.

CLERE-STORY.

27 Boss.
26 Vaulting Ribs (Transverse).
25        do.         (Longitudinal).
24 Vault.
23 Sill of C. Window.
22 Mullion of   do.
21 Tracery of   do.
20 Arch-mouldings of C. Arch.
19 Bases of Jamb of       do.
18 Capitals of                 do.
17 Jamb-mouldings of     do.
16 Clere-story String.

BLIND-STORY.
(Triforium.)

15 Capitals of Vaulting Shaft.
14 Tracery of Triforium.
13 Triforium-Arch.
12 Bases of T. Piers.
11 Capitals of   do.
10 Pier of T. (Secondary).
  9     do.      (Primary).
  8 Triforium String.

GROUND-STORY.

7 Corbel.
6 Vaulting-Shaft.
5 Pier-Arch.
4  do.  Band.
3  do.  Base.
2  do.  Capital.
1 Pier.

EXTERIOR COMPARTMENT.

CLERE-STORY.

28 Parapet.
27 Cornice.
26 Clere-story Buttress.
25 Flying Buttress.
24 Tracery of C. Window.
23 Window Arch.
22 Mullions of C. Window.
21 Sill of                do.
20 Jambs of           do.
19 Weather Table.

AISLE COMPARTMENT.

18 Aisle Roof.
17 Capping to Buttress.
16 Parapet.
15 Cornice.
14 Gurgoyle.
13 Canopied Set-off.
12 Plain Set-off.
11 Tracery.
10 Window Arch.
9 Mullion.
8 Sill.
7 Bases of Window Shafts.
6 Capitals of       do.
5 Jambs.
4 Canopied Niche.
3 String-Course.
2 Buttress.
1 Base-Course.

CHAPTER III.

EXTERIOR AND INTERIOR COMPARTMENTS.

The most perfect type of a church built in England, during the best ages of Church Architecture, may be said to contain the following essentials:—

1. The Ground Plan is after the form of the Latin Cross, and is divisible longitudinally into three portions; namely,

• The Choir,
• The Transepts,
• The Nave.

2. The Choir and the Nave, and occasionally the Transepts, are divided, by means of columns and