ARCHITECTURE. 



with an archivolt ; sometimes interrupted 

 at the summit with a key-stone, in the 

 form of a console, or marsh, or some 

 other appropriate sculptured ornament. 

 The archivolt rises sometimes from a plat- 

 band, or impost, placed on the top of the 



less than one quarter, nor more thanon*- 

 third of the breadth of the arcade. When, 

 the arcades form blank recesses, the 

 backs of which are pierced with doors or 

 windows, or recessed with niches, the 

 recesses should be at least so deep, as to 



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Piers -and at other times from an enta-T'keep the most prominent parts of the 

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blature, supported by columns on each 

 side of the arch. In some instances the 

 arches of arcades are supported entirely 



dressings entirely within their surface. 

 In the upper stories of the theatres and 

 amphitheatres of the Romans, the arcades 



by single or coupled columns, without stood upon the podia, or inner-pedestals, 

 the entablature ; as in the temple of 

 Faunus at Rome. This form is far trom 

 being agreeable to the eye ; it wants sta- 

 bility, as the columns would be incapable 

 of resisting the lateral pressure of the 

 arches, were they not placed within an- 

 other walled inciosure, or in a circular 

 colonade. In large arches the key-stones 

 should never be omitted, and should be 

 carried to the soffit of the architrave, 

 where they will be useful in supporting 

 the middle of the entablature, which 

 otherwise would have too great a bear- 



ing. 



When columns are detached, as in the 

 triumphal arches of Septimius Severus 

 and Constantino, at Rome, it becomes ne- 

 cessary to break the entablature, making 

 its projection over the intercolumns the 

 same as if pilasters had been used instead 

 of columns: or so much as is just suffi- 

 cient to relieve it from the nakedness of 

 the wall. This is necessary in all inter- 

 columns of great width, but should be 

 practised as little as possible, as it des- 

 troys the genuine use of the entablature. 

 W T hen columns are without pedestals, 

 they should stand upon a plinth, in order 

 to keep the bases dry and clean, and pre- 

 vent them from being broken. 



Arcades should never be much more, 

 nor much less, than double their breadth. 

 The breadth of the pier should seldom 

 exceed two-thirds, nor be less than one- 

 third, of that of the arcade ; and the an- 

 gular pier should have an addition of a 

 third, or a half, as the nature of the de- 

 sign may require. The impost should 

 not be more than one-seventh, nor less 

 than a ninth, of the breadth of the arch ; 

 and the archivolt not more than one- 

 eighth, nor less than one-tenth, of that 

 breadth. The breadth of the bottom of 

 the key-stone should be equal to that of 

 the archivolt ; and its length not less than 

 one and a half of its bottom breadth, nor 

 more than double. In groined porticos, 

 the thickness of the piers depends on the 

 width of the portico, and the superincum- 

 bent building ; but with respect to the 

 beauty of the building-, it should not be 



of the columns : perhaps as much for the 

 purpose of proportioning the apertures, 

 as to form a proper parapet for leaning 

 over. 



Colonades. A colonade is a range of 

 attached or insulated columns, supporting 1 

 an entablature. The interval between 

 the columns, measured by the inferior 

 diameter of the column, is called the in- 

 tercolumniation ; and the whole, area be- 

 tween every two columns is called an in- 

 tercolumn. When the intercolumniation 

 is one diameter and a half, it is called 

 pycnostile, or columns thick set ; when 

 two diameters, systyle ; when two and a 

 quarter, custyle ; when three, diastyle ; 

 and when four, araeostyle, or columns thin 

 set. A colonade is also named according 

 to the number of columns which support 

 the entablature, or fastigium:when there 

 are four columns, it is called tetrastyle ; 

 when six, hexastyle ; when eight, octo- 

 style ; and when ten, decastyle. The 

 intercolumniations of the Doric order are 

 regulated by the number of triglyphs, 

 placing one over every intermediate co- 

 lumn : when there is one triglyph over 

 the interval, it is called monotriglyph ; 

 when there are two, it is called ditri- 

 glyph ; and so on, according to the pro- 

 gressive order of the Greek numerals. 

 The intercolumniation of the Grecian Do- 

 ric is almost constantly the monotriglyph; 

 from this practice there are only two de- 

 viations to be met with at Athens, the one 

 in the Doric Portico, and the other in the 

 Propyl;ea; but these intervals only be- 

 long to the middle intercolumniations, 

 which are both ditriglyph, and became 

 necessary, on account of their being op- 

 posite to the principal entrances. As the 

 character of the Grecian Doric is more 

 massy and dignified than that of the Ro- 

 man, the monotriglyphic succeeds best; 

 but in the Roman it is not so convenient, 

 for the passage through the intercolumns 

 would be too narrow, particularly in small 

 buildings, the ditriglyph is therefore 

 more generally adopted. The arxostyle 

 is only applied to rustic structures of 

 Tuscan intercolumniations, where th,o 



