ARCHITECTURAL PROPORTIONS
_Introduction_
In architectural drawing concise draughtsmanship is essential, the
profiles of mouldings in particular should be well defined.
Architectural designs, which should always be drawn to scale, are
expressed geometrically, that is in plan, elevation and section. The
actual effect is therefore a matter of conjecture only to be grasped by
those familiar with the arbitrary form of expression. Perspectives are
generally made with a view to depicting the appearance to the
uninitiated, but are practically useless as working drawings.
The student is advised to take advantage of every opportunity of
studying existing examples in museums and elsewhere. This study should
not be confined to geometric drawings, but these should be supplemented
by sketches and careful observation. Attention should also be paid to
the profiles of mouldings.
A practice should be made also of making freehand sketches of the
various features, indicating broadly the effects of light and shade.
The study of architectural proportions should be methodical, and the
general divisions given here might advantageously be committed to
memory. When this is accomplished attention may be devoted to individual
features.
_System of Proportion_
It is customary, when any of the orders of Architecture are employed, to
adopt a system of proportions which has been evolved from the best
traditions of the past, and is generally accepted as the most
satisfactory.
Naturally these proportions are subject to modification to suit special
conditions or personal treatment. According to the academic method, the
diameter of the column is divided into two parts, which are called
Modules, and each of these is again subdivided into thirty divisions
called parts. This gives a scale by means of which all dimensions of
height and projection are obtained. Since the diameter of the column
forms the standard of measurement, the proportions of the relative parts
are constant and in no way influenced by the size of the structure.
This method, although very complete, is--owing to its multiplicity of
dimensions--somewhat laborious in practice, and the method here proposed
in its stead, though not claimed to be exact, will yet be found to be
sufficiently accurate for ordinary requirements.
It is proposed to deal here with the orders commonly employed in
Renaissance architecture. These were based by the early exponents of the
style on Roman examples. The Doric selected is that of Vignola, and is a
refined version of the order used in the Theatre of Marcellus at Rome.
The Ionic closely resembles the Roman Ionic order in the same building.
The Corinthian is the Roman example from the Pantheon.
_The Order_
An Order consists of a vertical column and a horizontal entablature,
while in some instances the column rests on a pedestal.
It is desirable before dealing with proportions to enumerate the various
parts of which an order is composed.
The column consists of a shaft, base and capital.
The shaft is circular on plan and invariably tapered.
The base is composed of mouldings, which are circular on plan, and a
rectangular block or plinth.
The capital is circular on plan, and in the Doric and Corinthian orders
is divided from the shaft by a necking moulding. The capital is
surmounted by a feature known as the abacus, which is rectangular on
plan, but varies in detail in the different orders.
Columns may be isolated or engaged, that is, built into walls so that
they form projections from the surface.
[Illustration: No. 153. Doric Order with Pedestal.]
The pilaster is always engaged, and is rectangular on plan, but
otherwise it has the same general features and proportions as the
column.
The entablature is the superstructure supported by the columns. It
consists of an architrave, which is the lowest part, a frieze, the
intermediate part, and a series of projecting mouldings known as the
cornice.
The pedestal, which occasionally forms a support for the columns,
consists of a plinth, die and capping. The lower part or plinth is
separated from the die by mouldings, and the capping is a projecting
course of mouldings forming a simple cornice.
To sum up a simple classification, which may be termed the triology of
the orders, will be found to assist the memory.
The Orders commonly employed are three--the Doric, Ionic and Corinthian.
(There are two others which are less used, and are really derived from
the other three: they are the Tuscan, which is a form of debased Doric,
and the Composite, which is made up of the Ionic and Corinthian).
The Order may be divided into three parts:
Pedestal, Column and Entablature.
These may again be sub-divided.
The Pedestal into Plinth, Die and Capping.
The Column into Base, Shaft and Capital.
The Entablature into Architrave, Frieze and Cornice.
The method of arriving at the proportions of the order is as follows. In
this division the pedestal is not taken into account, but is reserved
for later consideration.
_Doric Order_
Divide the total height into five equal parts. Then the upper fifth will
give the height of the entablature and an eighth of the remaining
four-fifths the diameter of the column. From this it will be seen that
the column is eight diameters high and the entablature two diameters. In
using the term diameter it must be understood that it is always the
lower diameter of the column that is referred to.
[Illustration: No. 154. General Proportions of the Orders.]
The capital is half a diameter high exclusive of the necking moulding,
and the base also is half a diameter. In all the orders the column is
tapered; the upper diameter is in each case five-sixths of the lower or
major diameter. The taper is not in a straight line, but a slight
curve, which is known as entasis. It is obtained by drawing the lower
third of the shaft vertical and from these lines springing a curve to
the upper diameter, which may readily be done by slightly altering the
angle of the pencil in ruling them.
The entablature is divided as follows: the architrave is half a
diameter, the frieze and cornice each three-quarters of a diameter.
_Ionic Order_
The total height should be divided into six parts. Then the upper sixth
will be the entablature, and one ninth of the remainder the diameter of
the column, hence the column will be nine diameters high.
The capital is half a diameter high; the base also is half a diameter.
The total height of the entablature is divided into ten parts, three of
these should be taken as the height of the architrave, three that of the
frieze and the remaining four that of the cornice.
_Corinthian Order_
The total height should be divided into six parts. Then the upper sixth
is the height of the entablature. A tenth of the remainder will be the
diameter of the column.
The capital is one diameter and one-sixth in height exclusive of the
necking moulding, and the base is half a diameter high, exclusive of the
top fillet.
The division of the entablature is the same as that of the Ionic, and
the mouldings, although more elaborate, are similar in character. The
architrave and frieze are each three-tenths of the height and the
cornice four-tenths.
It will be seen from the foregoing that the diameters of the three
orders are respectively one-eighth, one-ninth and one-tenth the heights
of the columns, and that the entablature is, in the Doric, two diameters
high or one fourth the height of the column; in the Corinthian also two
diameters or one-fifth the height of the column. The Ionic is
intermediate between the two.
_Doric Entablatures_
The Doric cornice is three-quarters of a diameter in height and one
diameter in projection from the face of the frieze, which should always
be in vertical alignment with the architrave.
It is convenient to divide the cornice height into three. The upper
third consists of a crowning cavetto moulding, supported by a cyma
reversa, under which is a facia or corona, in turn supported by a dentil
course. The lower third should be taken as the centre of the dentil
course, and if the height from the top of the cavetto to the underside
of the corona be bisected, the point of bisection should fall in the
centre of the intervening reversa.
_Mutules_
In orthodox examples of the order the underside or soffit of the corona
is decorated with a series of sunk panels. Those immediately over the
triglyphs of the frieze are occupied by rows of conical drops. A
variation of this and a treatment frequently employed is a series of
brackets known as mutules. They consist of a facia and a reversa, which
is carried round the upper edge to support the corona. When mutules are
used the dentil course is omitted.
[Illustration: No. 155. Doric Entablature, Vignola.]
The dentils are rectilinear blocks on a flat projecting band, and they
are supported by a cyma reversa moulding. A fillet beneath this moulding
completes the cornice. The reversa is about the same height as the
fillet, and the dentil course is about twice this height, but owing to
the soffit of the corona sloping slightly upward and inwards the full
height of the dentil facia is not apparent when drawn in elevation.
[Illustration: No. 156. Doric Entablature, with Mutules.]
Above the dentil facia is a small cavetto moulding and a fillet. These
are directly beneath the corona, and are carried round to form the
panels on its soffit.
The Doric frieze is three-quarters of a diameter high. It is divided
into panels technically known as metopes, by projecting features half a
diameter in width which are called triglyphs.
The metopes should be square, and one of the triglyphs is always placed
immediately over each column, having the same central axis, hence the
spacing of the columns apart is regulated by the triglyphs and metopes.
Examples of various spacings of columns will be given later.
The frieze is bounded above and below by rectilinear projecting bands or
fillets; that at the top breaks round or follows the projection of the
triglyphs.
The triglyphs are so named because they are channelled vertically with
grooves or glyphs, V shaped in section, with intervening spaces or
inter-glyphs. The width of the triglyph should be divided into twelve
parts--then the half glyphs which are placed at the angles will each be
one of these parts, and the remaining two glyphs and three inter-glyphs
are each two of them. The glyphs terminate at the base on the fillet
band, but at the top are cut off a little below the upper fillet,
invariably in a straight line, thus forming a triangular heading with
the apex of the triangle sloping backwards and downwards in conformity
with the V shaped section of the glyphs.
Under the lower fillet band, and immediately below the triglyph, is a
small fillet and six pendant drops of conical form known as guttae.
[Illustration: No. 157. Ionic Entablature.]
The architrave is half a diameter high, inclusive of the fillet band,
which is roughly a sixth of this height. The small fillet and guttae are
together equal in height to the fillet band.
It may be taken as an invariable rule that whatever order is used, the
face of the architrave must be in vertical alignment with the upper part
of the shaft of the column.
_Ionic Entablature_
The total height of the entablature is divided into ten parts; three of
these should be taken as the height of the architrave, three that of the
frieze, and the remaining four that of the cornice.
To find the projection of the cornice a line should be drawn at an angle
of 45 degrees from the top of the frieze, and the profiles of the
mouldings composing the cornice will fall within this line.
The lowest member is a small reversa moulding, with a fillet supporting
a dentil course, above which is an ovolo; these occupy half the height
of the cornice. The remaining half is composed of the facia, surmounted
by a reversa and the crowning cyma moulding, rather more than half of
the height being allotted to these two.
The frieze of the Ionic order has no characteristic detail as the Doric,
and may be plain or decorated according to conditions, and should be in
vertical alignment with the lowest member of the architrave. In some of
the later Renaissance examples the profile of the Ionic frieze is a
segmental curve of about a third of a circle.
The architrave is usually formed of three facias, which may be either
vertical or slightly inclined.
[Illustration: No. 158. Corinthian Entablature.]
A fifth of the total height is taken for the upper moulding, which is a
reversa with its accompanying fillet.
A point bisecting the underside of the fillet and bottom of architrave
will give the line of the lower edge of the top facia. The other two
facias should be taken in a decreasing ratio, the lower being the
shorter.
_Corinthian Entablature_
The division of the entablature is the same as that of the Ionic. The
total height is divided into ten. Three of these parts form the
architrave, three the frieze and four the cornice.
An angle of 45 degrees set off from the top of the frieze will determine
the general contour and projection of the cornice.
The cornice is more complex than in the other styles, but a division of
eleven will help to determine, three being the height to underside of
bead moulding and seven that of the main facia. The lowest moulding of
the cornice is a cyma reversa supporting a dentil course with a bead
moulding above it. Above the bead there is an ovolo, which forms the bed
of a series of brackets known as modillions. The height of the
modillions is about one-fifth including the reversa moulding, which,
besides completing the modillions, is carried round between them as a
support for the upper facia.
The modillions have a profile of ogee form. They are about a sixth of a
diameter in width and project about twice their width, and are so spaced
as to leave squares between them on the soffit or underside of the
corona. The frieze, which may or may not be decorated, is in vertical
alignment with the lowest member of the architrave.
The architrave is made up of three facias with intervening mouldings. If
the height be divided into two, the upper half is devoted to the first
facia and reversa moulding, which latter occupies rather more than
one-third; the remaining half is taken up by the other two facias in a
diminishing ratio.
_The Column--The Shaft_
The general proportions of the column have already been given. The shaft
is invariably tapered for two-thirds of its height, the lower third
being cylindrical, and the taper terminates at the necking moulding. In
all three orders the difference between the upper and lower diameters is
the same, that is, the upper is five-sixths of the lower, but although
the amount of taper is numerically the same, the different ratios of the
diameters to the heights produce naturally very different results.
The shaft of the Doric column may be plain or channelled with vertical
grooves called flutes. There are twenty of these flutes round the
circumference. On plan they are shallow, and may be formed of arcs of a
third of a circle. The curves meet without intervening fillets. The
flutes are finished off in segmental curves at the top and bottom,
leaving a small plain space below the necking and above the base.
The Ionic and Corinthian columns may have plain or decorated shafts. If
decorated they have twenty-four flutes round the circumference. These
are semi-circular on plan, and are spaced with fillets between them.
_The Capital_
The Capital is the culminating feature of the column in which horizontal
lines predominate in æsthetic contrast to the vertical lines of the
shaft. In all the orders there is some form of crowning block or
moulding known as the abacus.[A]
[A] Though the proportions given are approximately accurate for
general division, it will be found necessary in detailing to adopt a
more intimate system of measurement. In the following diagrams the
diameter is divided into 36 parts, which are expressed in figures,
giving heights, etc., of the various features.
_Doric Capital_
The Doric abacus consists of a rectangular slab, square on plan, which
in detail consists of a fillet and reversa moulding surmounting a facia.
Its extreme width is one and a half times the upper diameter. The square
abacus is supported by an ovolo, which is circular on plan, and is
connected with the necking by three small fillets.
[Illustration: No. 159. Doric Capital.]
The capital is half a diameter in height, exclusive of the mouldings
between the necking and the shaft, and the upper part to the underside
of the ovolo occupies rather more than half.
[Illustration: No. 160. Ionic Capital.]
The necking is a vertical extension of the upper diameter of the column,
and is separated from the shaft by a boldly projecting moulding, which
in height should be about equal to the three small fillets below the
ovolo. The moulding consists of a torus and a fillet, and a cavetto
curve is carried from the underside of the fillet and dies into the line
of the shaft of the column.
Sometimes the ovolo is decorated with its characteristic egg and tongue
detail, and occasionally the reversa of the abacus is also enriched.
The necking is sometimes ornamented with four rosettes, which are placed
centrally under the square faces of the abacus.
_Ionic Capital_
The Ionic capital is half a diameter high, and is readily distinguished
by its bolster-like form with voluted ends. This bolster is rectangular
on plan, and measures laterally rather more than one and a half
diameters, while from back to front it is slightly less than a diameter.
The shaft terminates in a cavetto curve, and is surmounted by a fillet,
a small torus and an ovolo moulding, which is invariably decorated with
egg and tongue detail. These mouldings all conform to the circular plan
of the shaft. On the ovolo rests the voluted bolster.
The abacus, which is square on plan, consists of a reversa moulding and
fillet.
From the top of the abacus to the base of the ovolo the height is about
a third of a diameter, and one-fourth of this height will give the
height of the abacus.
The centre or eye of the volute can readily be found by dropping a
perpendicular from the lower edge of the reversa to intersect the
horizontal line defining the base of the ovolo. This point of
intersection is the required centre.
_To Draw the Volute_
From this as centre and one part as radius describe a circle. Within
this circle draw a square, having for a diagonal the diameter of the
circle. Bisect the sides of the square and draw the diameters by joining
the points of bi-section. Divide these diameters of the square into six
and these points will be the centres for the segments of circles which
form the volute. Vertical and horizontal lines drawn from the centres
will define the extent of each segment.
[Illustration: No. 161. Ionic Capital, with angular volutes.]
For small scale drawings the volutes are drawn free-hand, but for larger
working drawings it is necessary to use some method such as that given
here.
The angle formed by the meeting of the ovolo and the volute is masked by
a detail of anthemion form.
The ends of the bolster between the volutes consist of concave or ogee
curves, which are symmetrically arranged from a centre line; moulded
ridges or conventional leaf detail decorate the centre.
The form of the Ionic capital, while suitable for a façade, requires
some modification if it is to be carried round the side of a building,
owing to the great dissimilarity in the front and side views. In this
case the end volute of the capital at the angle of the building is
projected forward at an angle of 45 degrees, and the side is then
treated in the same way as the front.
In late Renaissance buildings this difficulty was overcome by making all
the volutes project at angles of 45 degrees, so that the four faces of
the capital were uniform. This entails the bolster being dispensed with,
and the volutes, no longer connected laterally, spring directly from the
top of the ovolo moulding, and the space between the springing lines is
occupied by a husk.
[Illustration: No. 162. Ionic Capital. Detail of Angular Volute.]
As the volutes make equal angles they conform more or less to a square
plan. The plan of the abacus is composed of four concave curves with
small straight intervals at the meeting angles. The general proportions
for this form of capital are the same as for the bolster type.
_Corinthian Capital_
The Corinthian capital differs widely from those of the preceding orders
in proportion and detail.
Its general form may be described as a bell, which is circular on plan.
It springs from the upper extremity of the shaft, from which it is
separated by a necking moulding.
Under the abacus it terminates in a fillet.
The bell is one diameter high. The height of the abacus is one-sixth of
a diameter in addition; on plan the abacus falls within a square, having
four concave faces with short straight lines at the angles. The distance
across the diagonal is two diameters. The bell is clothed with leaves of
acanthus type, which are arranged in two tiers of eight leaves each.
Between the upper leaves are eight stems with husks and branching
scrolls, which terminate in volutes at the angles and centres.
The necking moulding consists of a small torus and fillet.
Although the arrangement of the principal features of the Corinthian
capital is horizontal, yet owing to the channelling of the leaves and
the firmly springing scrolls the vertical direction appears to
predominate.
This verticality emphasises the function of the capital as a supporting
feature, and is æsthetically satisfactory, being in harmony with the
flutings of the shaft.
[Illustration: No. 163. Corinthian Capital.]
The effect produced by the capitals of the other two orders is
horizontal, and suggests the idea of binding. They are equally
satisfactory as giving contrast of direction.
[Illustration: No. 164. Corinthian Capital.
Detail giving divisions of height, and profiles.]
_The Base_
In all the orders a square plinth is the lowest member of the base of
the column. On this plinth rests a series of mouldings which follow the
circular plan of the shaft. The shaft invariably terminates in a
fillet, the diameter of which exceeds that of the column, and on to
which the line of the shaft is carried by means of a curve.
[Illustration: No. 165. Doric Base.]
_Doric Base_
The Doric base is extremely simple. It consists of the square plinth on
which rests a torus moulding surmounted by a smaller moulding of the
same section and a fillet above.
The width of the plinth is one and a third the diameter of the column,
and its height a quarter diameter or half the total height of the base.
The other half is made up of the large torus, the small torus and
fillet. The torus moulding should be bold in projection, practically
semi-circular and at the fullest part of its curvature in vertical
alignment with the centres of the horizontal faces of the plinth block.
The small torus and fillet are about equal in height.
_Ionic Base_
[Illustration: No. 166. Ionic Base.]
The Ionic base differs from the Doric in the introduction of a hollow or
scotia moulding between the two torus mouldings. Æsthetically it may be
considered more satisfactory in that the strong shadow obtained by the
use of the scotia produces an effect of binding which adds to the
impression of strength. The type is technically known as the Attic base.
The total width is one and a third diameter.
The height of half a diameter may be divided into three. One of these
divisions will give the height of the plinth, one the large torus and
the fillet above it, and the other the scotia and small torus with the
fillets above and below. The fillets either side of the upper torus may
be in the same vertical alignment.
[Illustration: No. 167. Corinthian Base.]
The smallest diameter of the base, which will be in the hollow of the
scotia, should exceed the diameter of the shaft, or an effect of
weakness will be imparted.
As in the Doric base a curve of a quarter circle connects the shaft with
the upper fillet.
_Corinthian Base_
The orthodox base of the Corinthian order is similar to that of the
Ionic, with an additional scotia and small torus with its accompanying
fillets.
The width of the plinth is one and a third diameter.
The height of half a diameter does not include the top fillet. The
proportions may be approximated by dividing the height into four. One of
these parts will be the height of the plinth, another that of the large
torus and its fillet, the third--the upper edge of fillet of top scotia,
and the fourth that of the upper scotia and torus with the intervening
fillet. Vertically the uppermost fillet is in alignment with that of the
upper scotia, and the extremity of the upper torus with the small bead
mouldings dividing this from the lower scotia.
Although this is the orthodox Corinthian base, it is not used as
frequently as the Ionic type, but when the order is on a large scale the
more elaborate version is justified.
_The Arch_
When the arch is used in conjunction with the column it is supported on
pilasters which are attached to the columns. The columns and pilasters
thus form piers.
In the Doric order the columns are placed five diameters apart from
centre to centre, in the Ionic five and a quarter, and in the Corinthian
five and a half.
The necking moulding of the capital is generally carried through above
the arch, the outer line of which is struck so as to nearly touch the
underside.
The projection of the pilasters which carry the arch is half a diameter
from the outer lines of the column, and is measured on the same level as
the springing point of the arch.
The centre from which the arch is struck is sometimes in the same
horizontal line as the springing points, but more frequently a little
above the line and thereby a rather better effect is produced.
The arch-band or archivolt is the same width as the pilaster supporting
it, and a series of mouldings known as the impost is placed at the top
of the pilaster. The base of the pilaster consists of a plain plinth of
slight projection equal in height to the base of the column.
From the spacing of the columns and the proportions here given it will
be seen that the height and width of the aperture made by the arch and
pilasters are arrived at automatically, but if measured, the height will
be found to be about twice the width and the top of the impost about
two-thirds the height of the column. These proportions may be accepted
as giving satisfactory results under ordinary conditions.
As a general rule, in all the orders the impost is half a diameter high,
and so is the same as the projection of the pilaster and the width of
the archivolt.
This rule is not always adhered to, however, but in any case the width
of the archivolt should never be more than one-eighth or less than
one-tenth of the diameter of the arch, and should always be the same as
the width of the pilaster.
_Doric Impost_
The mouldings of the Doric Impost are as follows:
At the top there is a fillet and a bold ovolo, below which there is a
bead-moulding or small torus with fillet and two facias. The lower
facia, which is of slight projection is one-fourth of the total height.
The upper facia and fillet are half the remainder.
[Illustration: No. 168. Detail of Archivolts and Imposts.]
_Archivolt_
The archivolt mouldings are in the Doric order, the same as those of the
impost.
_Ionic Impost_
The total height of half a diameter may be divided into two, and the
upper half sub-divided into three. Then the upper division will be the
height of the top fillet and a reversa moulding; the second the height
of a facia and the third an ovolo and small torus.
The lower half of the impost consists of two facias, the upper of which
is broader than the lower.
_Ionic Archivolt_
The archivolt, commencing at the outer rim, consists of a fillet and
bold reversa moulding which occupies rather less than a fourth of the
total width, and two facias of unequal widths. The width of the inner
facia is nearly one-third more than that of the reversa moulding.
_Corinthian Impost_
The Corinthian impost differs from those of the other two orders in
having a necking and necking moulding in place of the two unequal
facias.
The total height should be divided into two, and the upper half divided
into four. Then the top fillet and reversa moulding will be one of these
divisions, the facia two, and the supporting ovolo will occupy the
remaining one.
The lower half of the impost consists of a small torus and fillet
beneath the ovolo, the necking, and the torus and fillet which form the
necking moulding.
_Corinthian Archivolt_
The archivolt, commencing at the outer rim, consists of a fillet and
reversa and three unequal facias.
If the total width is divided into two, the point of bisection will be
the centre of a small reversa moulding between the two outer facias. The
outer reversa and the inner facia are each about one-sixth of the total
width and the small reversa is about two-thirds of the inner facia.
_The Keystone_
A projecting block, or keystone, is sometimes used at the centre of the
arch. The face width of its lowest edge should not be less than the
width of the archivolt. Its height is not often less than one and a half
times or more than twice this width.
It may be decorated in various ways, and is frequently in the shape of a
console. This form is especially suitable when the keystone comes in
contact with the architrave of the entablature, in which case it is
capped with a moulded abacus.
_The Pedestal_
The height of the pedestal is a fourth that of the column and
entablature together, though this proportion may be varied to suit
different conditions. For instance, when the pedestal forms part of the
structure of a balcony or balustrading the height must be modified to
suit the special requirements of the position.
The pedestal is composed of plinth, die and capping.
The width of the die is the same as the plinth of the base of the column
above it, that is, one and one-third diameter. The projection of the
capping, which is the same for all three orders is obtained by drawing a
line at an angle of 30 degrees with the vertical from the top of the
die.
The width of the plinth corresponds to the projection of the capping,
and is determined by dropping perpendiculars from the top fillet.
The height of the mouldings between the die and plinth is determined by
a line drawn from the bottom of the die at an angle of 45 degrees to
intersect the vertical face of the plinth. The angle is the same for all
the orders.
_Doric Pedestal_
In the Doric order the height of the capping is one-third diameter. The
face of the die is square, and this determines the height of the plinth.
[Illustration: No. 169. Detail of Pedestals.]
The capping mouldings consist of a fillet, facia, ovolo, fillet and
cavetto. The facia is carried to the underside of the fillet in a curve,
and its height is half the total height of the capping. The facia is
supported by the ovolo, and a fillet and cavetto complete the capping.
The height of the course of mouldings at the top of the plinth should be
divided into three, then the upper third will contain a cavetto moulding
and fillet, and the remaining two-thirds an ogee and final fillet.
_Ionic Pedestal_
In the Ionic pedestal the plinth with its mouldings should occupy
one-third the height and the capping one-fifth the remainder.
The mouldings are similar to those of the Doric pedestal, but a little
more elaborate. In the capping a reversa is used under the top fillet
and a small torus or bead is placed between the ovolo and the cavetto.
In the mouldings of the plinth a similar bead is introduced above the
ogee moulding.
_Corinthian Pedestal_
The same general divisions as the Ionic will give the proportions of the
Corinthian pedestal, the difference being that of the scale and the
detail of the mouldings.
The capping may be divided into two. The top half consists of a fillet,
reversa and facia, and the lower half a supporting cyma recta, a bead
and a cavetto curve. The plinth mouldings are the same as those of the
Ionic pedestal with the addition of a torus beneath the ogee. The height
of this torus is one-fourth the total height and is about equal to that
of the cavetto and bead together.
When the pedestal is employed the arch becomes proportionately larger.
In the Doric order the columns are then spaced seven and a half
diameters apart; in the Ionic seven and three quarters, and in the
Corinthian eight diameters centre to centre.
The archivolt, the radius of which is determined by the above spacing,
is supported as before by an impost and pilaster. The base of the
pilaster consists of a slightly projecting block equal in height to the
plinth block of the pedestal.
The height of the arch varies slightly, inasmuch as the inner curve may
be about a diameter from the architrave, but in the Corinthian order
should not fall below the level of the necking moulding of the capital.
_The Baluster_
As already stated, the pedestal may be used as a part of a balustrading
associated with balusters, and must conform to the proportions
necessitated by the conditions. The usual height for balustradings,
whether to steps, balconies, or before windows, is three feet two
inches, though in special cases it may be slightly more.
The baluster is a species of small column. Its usual form is bulbous or
vase-shaped, and it is furnished with a capital and base. A series of
balusters is technically known as a balustrade.
The balusters are raised on a plinth, which corresponds to the plinth of
the pedestal, and surmounted by a rail of horizontal mouldings, which
correspond to the capping of the pedestal; hence the baluster is of the
same height as the die.
The height of the baluster should be divided into five, then one-fifth
will be the height of the base, and the capital exclusive of the necking
will be another fifth. The extreme diameter of the bulbous shaft is
one-third the total height of the baluster, and the diameter of the
necking and the top of the shaft is about one-sixth. The capital has a
square abacus slightly less in width than the plinth of the base. Below
the abacus is
[Illustration: No. 170. Detail of Balusters.]
an ovolo and fillet, which are circular on plan. The necking is
separated from the shaft by a small torus and fillet. The base has for
its lowest member a square plinth, which occupies rather less than half
the height and is equal in width to the extreme diameter of the bulbous
shaft. Above the plinth is a scotia and a necking moulding, which are
circular on plan.
_Spacing of Balusters_
The balusters should be spaced with not more than half their diameters
or less than a third between their bases, except when employed on the
rake of steps, when they may be slightly closer.
_Balustrading_
In a balustrading an unequal number of balusters should always be used,
and not less than five in one group exclusive of the half balusters
which are attached to the flanking or dividing dies. Seven and nine form
very satisfactory groups, but if more than nine are necessary for the
space to be filled, intermediate dies must be interposed, and these may
vary from two-thirds to three-quarters the width of the principal dies.
In some cases, when a large number of balusters are to be grouped, the
dies are flanked by half dies, which are less in projection than the
dies themselves.
Balustrades are sometimes used above the cornice of a building, and
their height should not be more than four-fifths or less than two-thirds
the height of the entablature. This height would be exclusive of the
plinth on which the balusters are raised. The height of the plinth is
determined by the height of the building, and the projection of the
cornice, as its purpose is to raise the balusters so that they may be
seen from the ordinary point of view. The principal dies may be placed
over columns or pilasters and should be equal in width to the upper
diameters of these, though flanking half dies may be used in addition to
avoid an appearance of thinness. The plinth and capping mouldings always
follow the plan of the principal dies, and are carried in unbroken lines
across each interval.
When the height of the balustrade does not conform to the orthodox
proportions the method of determining the relative proportions is as
follows:--The height is divided into seven parts; of these one part
gives the height of the capping, four the baluster and two the plinth.
The mouldings in character and detail are the same as those of the
pedestal, and should be in harmony with the order used.
When balustrading forms part of a stair, the height on landings should
be three feet two inches. On the rake two feet ten inches from the step
at a line vertical with the face of the riser. The plinth is invariably
used as a string enclosing the ends of the steps and following the rake
or angle in a straight line, and carried to the levels by means of
curving ramps.
In interior work the bulbous shafts of balusters are often decorated
with carved detail, and the mouldings also may be enriched.
_Use of Columns_
Columns were originally used in the porticos and courts of temples and
other buildings, and sometimes to form supports for vaulted roofs.
Wherever employed their function was directly structural, but this was
not the case at the time of the Renaissance. The requirements demanded
by widely different social conditions led to their being used more as
decorative than structural features.
The use of engaged columns and pilasters in a façade can be justified to
some extent. Although such columns and pilasters may not be absolutely
essential for support, yet they act as buttresses and add to the
strength of the structure with a certain economy of material. Also they
are æsthetically satisfactory in their effect of light and shade.
_Disposition and Spacing in Colonnades_
The disposition of columns either in a façade or a colonnade is
controlled by proportions which have been found to be desirable or are
necessitated by special features of the order itself. The latter is the
case with the Doric order, the spacing being determined by the trigylphs
and metopes. If the triglyphs are placed centrally over the columns or
pilasters the spacing of these apart will be two and a half diameters
centre to centre, three and three-quarters, or five diameters, with two,
three or four metopes respectively between them in the frieze. With the
wider spacing of five diameters it is usual to employ coupled columns to
add to the appearance of strength. As the triglyphs are one and a
quarter diameters apart centre to centre, the coupled columns are
brought very close together, entailing a slight modification of the
bases. Since the ordinary projection of the plinth of a sixth of a
diameter beyond the line of the shaft is not possible between the two
columns, the plinth-blocks are united, and the torus moulding made
slightly less in projection.
[Illustration: No. 171. Spacing of Columns.]
The capitals being less in width are not affected, a small interval is
left between the crowning reversa mouldings.
In the Ionic order the columns are spaced three and a quarter, three and
three-quarters and four and a quarter diameters centre to centre. The
coupled columns used with the wide spacing are one and a half diameters
centre to centre or half a diameter apart at the lower extremity of the
shafts.
The Corinthian spacing is slightly wider, three and a half diameters,
four diameters, or with coupled columns four and a half diameters centre
to centre. The coupled columns are placed as in the Ionic order one and
a half diameters centre to centre.
It is desirable that attention should be given to the vertical alignment
of the principal features. Dentils and modillions and indeed all
strongly marked features should centre with the columns, and be equally
spaced in the intervals.
_Orders Above Orders_
Occasionally in façades orders are used above one another. The Colosseum
is an antique Roman example of this, and it was a treatment often
adopted by the architects of the early Renaissance. It is desirable that
the simpler order should be the lower one. Ionic may be used over Doric,
or Corinthian over Ionic.
It is obvious that the central axes of the columns or pilasters of each
order used should be in vertical alignment, not only when seen from the
front, but in the case of detached columns, from the side view also.
When engaged columns or pilasters are employed, the upper tier may be
set back slightly from the face of the lower order which supports it; an
example of this is to be found in the Theatre of Marcellus at Rome.
The proportions of the upper order are obtained by making the lower
diameter of the upper tier of columns or pilasters equal to the upper
diameter of those
[Illustration: No. 172. Order above Order.]
of the supporting order, and an effect of continuous tapering is
produced.
It is usual to place above the entablature of the lower order a plinth
on which the bases of the upper columns rest. The height of the plinth
is regulated by the point of view, as its purpose is to display the
bases of the imposed order above the projecting cornice. Generally this
height will be about half a diameter.
In many historical examples the upper columns are placed on pedestals,
but this treatment, although useful when a balcony is desired, is not to
be recommended as the extra width and projection which the use of the
pedestal entails, gives an appearance of undue weight to be borne by the
supporting columns. If balconies are necessary they may terminate with
their own pedestals, which can be kept clear of the columns and should
not exceed them in projection.
_The Pilaster_
It may be as well to deal here with the treatment of pilasters, which
may be defined as columns in bas-relief. Their projection may vary from
one-half to about one-sixth their face width, though in antique examples
it is sometimes much less than this. In the pilasters of the Pantheon at
Rome it is one-tenth.
The projection is, however, partly determined by the order with which
the pilaster is used, as an appearance of mutilation might easily be
produced in the capitals of the Ionic and Corinthian orders. The Doric
capital, being composed of moulded profiles, is not in any way affected
by the amount of projection. Nor does the Ionic capital suffer when the
volutes are in one plane except when used on an angle. But if the later
Renaissance type with the volutes arranged at angles of 45 degrees is
employed, the projection of the pilaster must not be less than half its
upper diameter, so that the volute on the return face may be complete.
The Corinthian capital would be affected in the same way, and should
also be not less than half a diameter in projection in order to obtain a
satisfactory result.
The pilaster is usually tapered, and when associated with columns and
supporting the same entablature it is essential to preserve universal
alignment in the upper extremities and the architrave, but when used by
itself the pilaster is often not tapered. At the angle of buildings,
where both faces are displayed, it is an invariable rule that pilasters
should be straight.
The details of capitals and bases are the same as those of the columns.
When fluting is employed an odd number of channels should be used,
usually seven on the front face.
[Illustration: No. 173. Doric Order. Treatment of coupled Column and
Pilaster.]
_Arcades_
Arcades, as already suggested, may be composed of a series of arches,
supported on pilasters which flank the columns. The backs of the piers
thus formed may be treated with pilasters, which can be repeated on the
opposite wall, with the architrave frieze and cornice above.
There are several alternative treatments for the ceilings of arcades.
They may be flat and panelled by beams carried across in a line with the
pilasters and with a cornice moulding carried round the sides of the
beams.
[Illustration: No. 174. Doric Arcading.]
The interior can also be vaulted by means of archivolts springing from
the line of the imposts. The archivolts should be supported by pilasters
at the back of the piers and on the opposite wall, and a cornice may be
carried round between the vaults. Cross vaulting also may be employed,
and in this case the entablature is no longer necessary.
The proportions already given determine the width of piers when an order
is used, but when an order is not used some further general rules for
proportions are necessary.
The height of the opening formed by arches, which may spring from
piers--with or without an impost--should be about twice the width. The
supporting piers should not be less than a third or more than
two-thirds the width of the aperture. In any form of arcading, piers
must be employed at the angles, and these should be wider than the
intermediate ones by a half, a third, or a fourth.
[Illustration: No. 175. Doric Arch, with pedestal.]
_Subsidiary Order_
A secondary or subsidiary order is sometimes used in an arcading. The
height of the arch should then be twice its width, and the height of the
small order two-thirds the height of the column of the principal order.
This height of two-thirds the column should be sub-divided into nine
parts, of which eight will give the height of the column and the
remaining one that of the entablature. The entablature consists of
architrave and cornice, the frieze being omitted, and a division into
five will give the relative proportions. Two-fifths may be taken as the
height of the architrave and three that of the cornice.
[Illustration: No. 176. Employment of the Subsidiary Order.]
Pilasters are used with the columns of the subsidiary order with a space
of half a diameter between them and the columns.
[Illustration: No. 177. Subsidiary Order. Division of Entablature.]
The archivolt should be equal in width to the upper diameter of the
column, and the width of the lower edge of the keystone should also be
of the same dimension.
The subsidiary order may be the same as the principal order, but more
often the Ionic is used in conjunction with the Doric, or the Corinthian
with the Ionic.
As regards the treatment of the bases, the horizontal alignment must be
maintained. It is obvious that if the height of the base of the large
column is adopted for the subsidiary one it will be very much out of
proportion. This can be obviated by carrying through the plinth of the
larger column to form a step on which the base of the smaller rests, and
always the top line of the smaller bases should agree with that of the
larger.
_Superimposed Orders_
When arcades are used one above the other, the lower order is usually
mounted on a plinth, and the upper furnished with a pedestal. The height
of the pedestal is determined by the balustrading or balcony, the height
of which is governed by its use.
If the Doric is taken as the lower order the centres of the columns are
six and a quarter diameters apart, which gives a frieze of five metopes
with intervening triglyphs. The plinth on which the order stands is
three-quarters of a diameter high. The pilaster supporting the archivolt
projects half a diameter, and the height of the arch is determined by
the impost, which is two-thirds the height of the column inclusive of
the plinth. The base of the pilaster may be moulded, but the top line
should coincide with the top of the plinth.
Above the Doric an Ionic order might be placed, and the die and plinth
of the superimposed order should be kept as narrow as possible so as to
reduce the impression of weight. The pilasters carrying the arch rest on
the plinth of the pedestal, and the plinth mouldings are carried round
the bases. The plinth and rail of the balustrading should not project
but be kept between the pilasters.
The centres of the arches of both tiers are in a line with the tops of
the imposts, and the outer edges of the archivolts may nearly reach the
lower lines of the architraves.
When the Ionic is used as the lower order it may be surmounted by the
Corinthian. The distance between the centres of the lower columns should
then be six and a half diameters. The other proportions can be obtained
in the same way as the preceding.
If a subsidiary order is employed the columns of the principal order are
placed further apart. In the case of the Doric the distance is seven and
a half diameters, and the other orders are increased in proportion.
_Rustication_
The joints of the material used must necessarily be considered, and when
plain piers or plain wall surfaces occur the joints may readily be
accentuated and so turned to decorative account. The edges of the stones
forming the separate courses may be chamfered or moulded. The joints may
also be worked so as to form a square recess.
[Illustration: No. 178. Rustication.]
The surface of the stone is sometimes roughly tooled or frosted, or
worked in an arbitrary pattern, which is termed “vermiculated.” This
treatment probably gave rise to the word rustication.
When rusticated work is used with an order the height of each course of
stone should not be less than half a diameter, and when square recessed
joints are used they can be one-eighth or one-tenth the height of the
course.
Occasionally only the horizontal courses are thus marked, and this has
been objected to as producing a boarded appearance, though undoubtedly
the horizontal effect is at times agreeably in contrast to the vertical
features. A much more usual treatment in Renaissance examples was to
emphasise the vertical joints also.
The length of each stone should be from one and a half to three times
the height.
Rustication may be used in the formation of the arch, which frequently
has at its springing line a slightly projecting course, in which the
vertical joints are not emphasised.
[Illustration: No. 179. Rusticated Arcade.]
Rustication is also used in columns, either square on plan or conforming
to the plan of the column.
Its most legitimate employment is in basements and to emphasise the
angles of buildings.
_Basement_
A basement is really a continuous pedestal on which an order rests. It
necessarily varies in height according to conditions, thus if its
purpose is merely to raise the ground floor it may be no more than three
to six feet high, but if it is required to form a storey, it should not
exceed the height of the order employed or be less than one half.
The joints of the work in basements are generally accentuated by some
form of rustication, and the heights of the horizontal courses should
not be less than half a diameter of the column of the order above.
When a high basement is used it is sometimes crowned with a cornice, or
more frequently with a slightly projecting facia technically known as a
plat-band. In either case, the height should be equal to that of the
courses exclusive of moulded edges or chamfers. Also a plinth is placed
at the base of the same height as the plat-band or a little more. When a
cornice is used the plinth should be moulded and may then exceed the
height of the courses.
_Attic_
An attic storey is sometimes used instead of a second order, and this
may vary from one-third to one-tenth the height of the order beneath it.
The attic may be quite plain, but it often has breakings or projections
on its face corresponding to the vertical features of the supporting
order.
It usually forms a storey in a building, and then is of necessity
pierced with windows.
In architectural design the character and requirements of the building
must, of course, be the first consideration, but the basement may
constitute the ground floor, the height occupied by the order may
contain two stories and the attic may be an upper floor.
When an order is not employed the divisions and proportions already
stated may still be applied, the heights and widths should govern each
other as would be the case if the façade were divided into bays by
columns or pilasters.
In the absence of the order a cornice is substituted for the
entablature, and this, according to different authorities, may be from
one-twelfth to one-sixteenth the total height from the ground, but
one-fourteenth or one-fifteenth will be found a safe mean.
_The Pediment_
The pediment in its original and orthodox employment was a gable
conforming to the pitch of the roof. It is framed with mouldings, and
the enclosed space is technically known as the tympanum.
[Illustration: No. 180. Cornice where order is not employed.]
The use made of the pediment by the architects of the Renaissance was
not always justified in the strictest sense. It was often used to vary
the sky line, and to form door and window heads. Although the latter use
can be to some extent justified in exterior work, a similar employment
in interiors may be open to question.
The sloping lines of the pediment are not always straight, sometimes
they are in the form of a curve composed of a segment of a circle. The
triangular and curved forms are often used alternately in a row of
windows with good effect.
The lines of the pediment mouldings are not always continuous; sometimes
the sloping or the horizontal lines or both are broken. This is a
treatment that cannot readily be justified as the pediment is a feature
that implies shelter.
Sometimes ogee curves take the place of the straight sloping lines, and
these terminate towards the centre, with scroll ends, leaving an
interval between them.
[Illustration: DETAIL OF PEDIMENT
No. 181.]
The mouldings of the pediment are the same as those of the cornice, the
crowning moulding of which is carried round and omitted in the
horizontal course forming the base of the pediment.
Beneath the cyma the mouldings of the cornice are repeated in their
proper order, detailing at the lower angles on the top of the horizontal
cornice, which terminates with the fillet above the facia.
When dentils and modillions are introduced in the cornice they are
invariably repeated in the mouldings of the pediment.
The tympanum or face of the pediment should be in vertical alignment
with the face of the frieze. When this space is small it is best left
plain, but on a large scale the tympanum affords a very suitable
position in which to place sculpture.
The height of the pediment varies according to the width. Thus where the
base is short, as in door and window heads, it will be comparatively
higher than when used in a façade. The height may vary from a fourth to
a fifth of the width of the base.
_Doors_
Obviously door openings should be of sufficient size to admit the free
passage of a tall person. The minimum height for ordinary doors in
domestic buildings should be six feet nine inches, and the width two
feet nine inches. For entrance doors under similar conditions the width
may be three feet six, but when it is more than this the door should be
in two halves.
[Illustration: No. 182. General proportions of doors and windows.]
The size of doors should be proportioned to the building, and should be
designed to meet probable requirements, thus in public buildings door
openings should not be less than six feet wide.
Generally a satisfactory proportion may be obtained by making the height
twice the width, and the framing architrave one-sixth the width of the
opening.
If a frieze and cornice are carried over the door the height inclusive
of architrave should be half the width of the opening.
[Illustration: No. 183. Door Treatment.
A. Architrave with simple pilasters and consoles.
B. Ionic order rusticated, with pediment.
C. Doric order with pediment.
D. Doric order rusticated.
]
In addition to the framing architrave narrow pilasters bearing consoles
supporting the cornice are sometimes used. The total width of architrave
and pilaster may be about one-third the width, and the entire
entablature one-third the height of the opening.
The mouldings and decorations used should be in harmony with the general
structure and in character with the order if one is used.
Occasionally columns or pilasters are introduced, with or without the
arch, but the same general proportions apply, the aperture being two
squares.
When doors are placed under arches the top line of the entablature
should agree with that of the impost.
When a pediment is used, the height should be one-fourth the width of
the base.
_Windows_
The general proportions and treatments of doors apply also to windows,
and if doors and windows are placed in the same line the heads of the
openings should be in horizontal alignment. If this is not possible the
top of the cornice may agree with the inner line of the window openings.
Windows terminate below in a sill, or sometimes in a balcony, and as a
general rule those on the same level should be similar in treatment, but
an alternation such as already suggested with curved and straight lined
pediments is quite satisfactory.
The frieze and consoles of doors and windows are often decorated with
relief ornament.
When a façade is divided by columns or pilasters the bays are pierced
with windows ranged above each
[Illustration: No. 184. Windows.
A. Rusticated Architrave.
B. Rusticated Ionic Columns.
C. & D. Rustication with Horizontal and Vertical Joints Defined.
]
other, the heights varying with the different floors. Those on the first
storey are usually of full height, and those above less in height and
simpler in treatment. The width of apertures should be the same for the
different levels, except in the case of basements, where they may be
narrower.
When an order is not employed in a façade variety may be obtained by
grouping the windows; or three-light windows may be introduced. The
centre light, which may be treated with an arched head, should be twice
the width of the side lights.
[Illustration: No. 185. Three-Light Window.]
The number of windows in a façade should be odd, so that there may be a
centre one, and the end windows of a range should be kept well clear of
the angles of the building.