windows, doors, and other features in Gothic buildings.

PERP. } The Gothic architecture of the fifteenth century
PERPENDICULAR. } in England. _Abbreviated_ Perp.

PIER.--(1) A mass of walling, either a detached portion of
a wall or a distinct structure of masonry, taking the place
of a column in the arcade of a church or elsewhere; (2) a
group or cluster of shafts substituted for a column.

[Illustration: FIG. _C C_.--EARLY ENGLISH PIERS.]

[Illustration: FIG. _D D_.--LATE DECORATED AND PERPENDICULAR
PIERS.]

PILASTER.--A square column, usually attached to a wall;
frequently used in Classic and Renaissance architecture in
combination with columns.

PINNACLE (in Gothic architecture).--A small turret, or
ornament, usually with a pointed top, employed to mark the
summit of gables, buttresses, and other tall features.

PITCH.--The degree of slope given to a roof, gable, or
pediment.

PLAN.--(1) A map of the floor of a building, showing the
piers, if any, and the walls which inclose and divide it,
with the openings in them; (2) the actual arrangement and
disposition of the floors, piers, and walls of the building
itself.

PLANE.--The imaginary surface within which a series of
mouldings lies, and which coincides with the salient and
important points of that series. Mouldings are said to be on
an oblique plane when their plane forms an angle less than a
right angle with the face of the wall; and in receding
planes, when they can be divided into a series of groups of
more or less stepped outline, each within and behind the
other, and each partly bounded by a plane parallel with the
face of the wall.

PLASTER.--The plastic material, of which the groundwork is
lime and sand, used to cover walls internally and to form
ceilings. Sometimes employed as a covering to walls
externally.

PLINTH.--The base of a wall or of a column or range of
columns.

PORTAL.--A dignified and important entrance doorway.

PORTICO.--A range of columns with their entablature (and
usually covered by a pediment), marking the entrance to a
Renaissance or Classic building.

PRISMATIC RUSTICATION.--In Elizabethan architecture
rusticated masonry with diamond-shaped projections worked on
the face of each stone.

PROFILE.--The contour or