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where the beams meet, which afford them great support:they also obviate the necessity of using beams of aconsiderable length, and relieve them from the pressure ofthe diagonal timbers.

The cavaedium displuviatum is that kind in which thetimbers, supporting the gutters, are so inclined, that thewater dripping from the eaves is thrown back towards thewalls \ This kind is favourable to the admission of lightinto the winter triclinia, because the compluvium is elevated:but on the other hand, great inconvenience arises from thenecessity of constant repairs; for the pipes which conveyaway the water flowing from the eaves and from the gutterssurrounding the walls, do not always discharge themselvessufficiently fast. The water, therefore, overflowing thegutters, decays the wood-work and injures the walls.

The cavaedium testudinatum is used where the width ofthe court is not very great: and spacious apartments areconstructed over them.

1 Various conjectures have been offered as to the manner in which the porticoessurrounding the court were roofed; none of which will answer in every respect tothe context. There cannot be any doubt that the roofs of the cavaediumdispluviatum, in contradistinction to those of the other kinds of cavaedia, wereinclined towards the walls of the court; by which means the rain, falling from the eavesabove upon the roofs of the porticoes, was reflected towards the walls. The words ofVitruvius are as follows: Cf Displuviata autem sunt in quibus deliquiae, arcamsustinentes, stillicidia rejiciunt.” The foregoing supposition is confirmed by asubsequent passage, in which an objection to this mode is stated to arise from theprobability of the gutters overflowing, and damaging the walls: whence it is evidentthat the gutters must have been adjoining the walls. See the explanation of Plate I.