Page:Vitruvius the Ten Books on Architecture.djvu/154

122 their height one third of the width of the temple, and the dimi­nution of a column at the top, one fourth of its thickness at the bottom.

3. The height of their bases should be one half of that thick­ness. The plinth of their bases should be circular, and in height one half the height of the bases, the torus above it and congé being of the same height as the plinth. The height of the capital is one half the thickness of a column. The abacus has a width equivalent to the thickness of the bottom of a column. Let the height of the capital be divided into three parts, and give one to the plinth (that is, the abacus), the second to the echinus, and the third to the necking with its congé.

4. Upon the columns lay the main beams, fastened together, to a height commensurate with the requirements of the size of the building. These beams fastened together should be laid so as to be equivalent in thickness to the necking at the top of a column, and should be fastened together by means of dowels and dove-tailed tenons in such a way that there shall be a space two fingers broad between them at the fastening. For if they touch one another, and so do not leave airholes and admit draughts of air to blow between them, they get heated and soon begin to rot.

5. Above the beams and walls let the mutules project to a dis­tance equal to one quarter of the height of a column; along the front of them nail casings; above, build the tympanum of the pediment either in masonry or in wood. The pediment with its ridgepole, principal rafters, and purlines are to be built in such a way that the eaves shall be equivalent to one third of the com­pleted roof.

1. are also circular temples, some of which are con­structed in monopteral form, surrounded by columns but without