ARCHITECTURE. 
port their own entablatures, which must be 
the consequence in insulated columns. 
When the front of a building is to have 
two or more orders in the altitude, the suc- 
cession ought to be complete, otherwise the 
harmony will be destroyed by the violent 
contrast of the parts. When columns are 
attached, a recedure of the superior order 
will not offend the eye in any great degree, 
nor will the solidity of the structure be im- 
paired : this is to be seen in the theatre of 
Marcellus ; but when the stories of orders 
are insulated, it is necessary that the axis of 
the superior and inferior columns should be 
in the same vertical lines. If the upper or- 
der only insists in the middle of that below 
in two equidistant parts from the middle, 
the portions of the entablature of the lower 
order in which there is no superior order 
are generally finished with a balustrade, 
level with the sills of the windows. 
In England we have few examples of 
more than two ranges of columns in the 
same front ; for when there are three, it is 
difficult to preserve the character of each 
order in the intercolumnial decorations, 
without some striking defects. The first 
and second orders should stand upon a 
plinth, and the third also when there is one ; 
the point of view regulating the two upper 
plinths. In this case pedestals should be 
omitted in the upper orders, and if there 
is one, or a balustrade under the windows, 
the base and cornice should have but a small 
projection, and should be continued to pro- 
file upon the sides of the columns. In raising 
stories of arcades upon each other, with or- 
ders decorating the piers, the inferior co- 
lumns should be placed upon a plinth, and the 
superior ones upon a pedestal, in order that 
the arches may obtain a just proportion. 
Pediments. A pediment is a part of a 
building having a horizontal cornice below, 
and two equally inclined ones, or an arched 
cornice above, joined at the extremities of 
the horizontal one ; the cornices including a 
plane surface within, called the tympanum, 
which is therefore either a triangle or the 
segment of a circle. 
This definition does not comprehend 
every species of pediments which have been 
absurdly introduced; but it may be said to 
be tire only genuine one, as pediments re- 
present the ends of roofs, and were origi- 
nally intended to discharge the rain from 
the middle of the building, by compelling it 
to descend and fall over the flanks or ex- 
tremes, and not over the front, which must 
be the case with every other, figure that 
can be introduced except those of a' poly- 
gonal form, which present their interior 
angles to the horizontal cornice, or the exte- 
rior ones upwards. To find the pitch of the 
pediment Vitruvius directs as follows : di- 
vide between the extremities of the cyma- 
tium of the corona into nine equal parts, 
and one makes the height of the tympanum ; 
but this rule is not correct, as the tympa- 
num will vary its angles according as there 
are more or less mouldings of the inclined 
cornices within the extremities of the cy- 
matium of the corona; for since the mid- 
dle part by this rule is invariable, and the 
broader the parts are of the inclined cor- 
nices within each extremity of the cyma- 
tium of the corona, or rather within the 
under edge of the fillet of the sima upon 
each inclined cornice, the less is the base of 
the tympanum, and consequently the ver- 
tical angle less obtuse, and the base angles 
less acute ; but if this height extended to 
the meeting of the two under sides of the 
fillets of the sima, or crowning moulding, 
then the figure of the tympanum would be 
invariable. The Vitruvian rule has been 
thought by many to be too low ; but it is to 
be recollected, that that of the Parthenon 
at Athens, which has an octostyle portico, is 
nearly of this propor tion ; that of the temple 
of Theseus, which has an hexastyle portico, 
is about one- eighth; that of the Ionic 
temple on the Ilyssus, and of the Doric 
portico, which are both tetrastyle, are about 
one-seventh; the tympanum of the pedi- 
ment of the door on the Tower of the 
Winds is about one-fifth of the span. The 
edifices here mentioned are all Athenian 
buildings. From this comparison it would 
appear, that a kind of reciprocal ratio sub- 
sists between the extension of the base of 
the tympanum, and its height. Indeed, if 
a fixed ratio were applied to windows, the 
pediment would frequently consist of a 
cornice without the tympanum. It is there- 
fore with great reason that we often make 
the pitch of pediments of windows more 
than those which crown porticos, or the 
fronts of buildings. The plinths by which 
pediments are sometimes decorated are 
called acroterions, or acroters: the two 
which present triangular faces at the ex- 
tremes, have their heights, according to 
Vitruvius, half of that of the tympanum, and 
the middle one saddled on the summit is 
one-eighth part higher than those at the ex- 
tremes. Pediments owe their origin most 
probably to the inclined roofs of primitive 
huts. Among the Romans they were only 
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