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Construction. drawing (Fig. 27) shows the possible construction of the which stood over the Palace of Xerxes at Persepolis, where we find a column of close upon twenty metres in height. The architrave is composed of three beams put one upon the other, and two deep. Above are the joists^ the projecting ends of which look like a row of dentels ; whilst in the interior of the edifice they form the Boor and the ceilings* as well as compartments of the latter. Then comes a second row of beams, parallel to the architrave, supporting struts upon which rests a second floor. The latter, covered perhaps with metal, prevented the rain from percolating the clay bed, and thence the ceilings. We have taken advantage of this arrangement to contrive, on the left side of the . facade, a kind of patrol walk, in line with the bottom of the crenelation that runs round the roof. Struts and horizontal beams make up the framework of the flat covering. This is supported by the lower floor, which is much stronger than the upper, and extends over the entire building. Above it was a brick floor, and over it again a bed of earth or sand. Our sketch exhibits the two processes which could be employed to make the roof water-tight ; namely, a brick or tile flooring. The waters would have no effect upon this cuirass, and, as the sides were slightly inclined, they would rush down the polished surface and discharge themselves either directly, or run into gutters which would pour them out at some distance from the foot of the wall. Imposing though these lofts may be, both from their salience, their massiveness, and the enormous fields they yield for decora- tion, their elements are precisely the same as those of smaller buildings. Oblique and curvilinear pieces are conspicuously absent from both ; the lines are all horizontal or vertical, and the joining of the timbers is done by halving ; that is to say, by cutting away an equal portion in depth of each, so as to let them into each other, as will be seen by reference to our illustration (Pig. 27). Our restitution of the attic in the Hall of a Hundred Columns (Fig. 28) is carried out on this sani<' principle of lavish display of woods. In it we show how. without complicating the timber frame, vertical lights could be devised when the windows and doors pierced in the wall surrounding the vast editice were inadequate to let in sufficient light. 1 o do this it only required slightly to raise the central part of the roof, and contrive slits in the squared beams intervening between the two Uoors, when through these open Digitized by Google