1. ALBERTI, De Re Aedificatoria, VII ( 1450)

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The columnar pattern comprises the following: the pedestal and, on top of that, the base; on the base, the column, followed by the capital, then the beam, and on top of the beam, the rafters, their cut-off ends either terminated or concealed by the frieze; finally, at the very top comes the cornice.
I feel that we should begin with the capital, being the element that varies the most.
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It was Necessity who instructed that a capital should sit on top of the column, to serve as a base for the joints of the beam timbers; originally it was a shapeless piece of roughly squared wood. The inhabitants of Doron (if the Greeks are to believed in everything) were the first to put it to the lathe, and to make it look like a round dish set under a quadrangular lid; because this seemed too cramped, they raised it on a slightly higher neck.
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8. To return now to the subject of the capital. The Dorians gave their capital the same height as the base, and divided it into thirds, the first being occupied by the abacus, the second by the echinus, and the third and last by the collar of the capital, which lay below the echinus.
The abacus has a width and depth one and one twelfth times the diameter at the base of the column. The abacus contains a border and a die. the border is formed by a gullet, and takes up two fifths of the abacus. The upper edge of the echinus meets the end of the abacus. Running around the bottom of the echinus there are either three tiny rings or a gullet, serving as ornament and taking up no more than a third of the height. The collar (the bottom part of the capital), as in the case of all capitals, is no wider than the column itself.
In other cases - as we have observed in the lineaments of ancient buildings - the height of the Doric capital has been made three quarters the diameter of the base of the column, and the overall height of the capital has been divided into elevenths, four being allotted to the abacus, and also to the echinus, but three to the colla. The abacus has then been divided in two, the top being a gullet and the bottom a fascia; the echinus is then also divided in two, the bottom being given over either to rings or to a gullet, running around the base of the echinus. To the collar are attached either roses or leaves in relief. So much for the Doric.

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9. The beam is set on top of the capitals, once they have been placed in position, and on top of the beam are set the cross-beams, boards, and other parts that make up the roof.

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The Dorians made their beam at least as wide as half the diameter at the base of the column. They gave their beam three fascias; below the top one, severals short battens were attached; on the underside of each of these were fixed six nails, intended to hold in place the cross-beams, which projected from the wall to the level of the battens: clearly this device was to prevent them from slipping inward. The overall height of the beam was divided into seven units, from which were derived all the measurements of the elements described below. The lowest fascia was four units high, the middle one, next to it, six, and the top one took up the remaining two units. Of the six units of the middle fascia, one was taken up by the battens, and another by the nails fixed beneath. The battens were twice six units in length. The blank spaces between the ends of the battens were twenty minus two units wide. Over the beams are set the cross-beams, whose ends are cut at right angles, and which stand out half a unit. The width of these cross-beams should equal the the thickness of the beam, and their height should be half as much again, or twice nine. Up the face of the cross-beams are incised three straight grooves, cut at right angles equidistant, set at intervals of one unit. The edges on either side were chamfered to a depth of half a unit. The gaps between the cross-beams in more elegant work are filled with tablets, as broad as they are high. The cross-beams are set vertically above the solid of each column. The faces of the cross-beams stand out half a unit from the tablets; the tablets, meanwhile, are flush with the lower fascia of the beam below. In these tablets are sculpted calves' skulls, roundels, rosettes, and so on. Each of the cross-beams and tablets has, as a border, a platband two units high.
Above this there is a plank, two units thick, its lineaments those of a channel. In its thickness there extends a pavement - as I might describe it - three units wide, its ornament of small eggs based, unless I am mistaken, on the stones shat stand out from the mortar in paving. On this are set mutules, of equal width to the cross-beams, projecting out twelve units and cut perpendicularly to the level. The mutules are bordered by a gullet three quarters of a unit thick. On the underside, between the mutules, were carved rosettes and acanthus.
Above the mutules sits the cornice, four units in height. This consists of a platband with a gullet border. The latter takes up one and a half untis. If the work is to have a pediment, every layer op the cornice is to be repeated in it, and within each layer each particular element should be set at the corner angle and be aligned exactly with the others along the plumb. the difference between the pediment and the top of the cornice, however, is that at the top of a pediment there is always a border of a wave, four units high in the case of the doric order, to act as a rainwater drip; but in a cornice it is only included when there is to be no pediment above. But more about pediments later. So much for the Dorians.

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Cannels run down the column in either a straight line or a spiral. In the Dorian one, the channels run straight down the column and are referred to as 'flutes' by the architects; the Dorians have twenty such flutes. In the other orders there are twenty-four; these are separated one from another by fillets, no more than a third and no less than a quarter the width of the groove. The groove itself has a semicircular lineament. The Dorians, ont he other hand, have no fillets: the flutes are simple, sometimes straight, more often with grooves no greater than a quarter circle, and meeting continuously along an edge.

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Here below is a list of dimensions op particular use to the workman in setting out the columns. The method is based on the number of columns to be contained in the work. To begin with the Doric: if there are to be four columns, the front of the elevation is divided into twenty-seven parts; if there are to be six, it is divided into forty-one; but if there are eight, it is divided into fifty-six. Each column takes up two of these parts.