For galleries and terraces open to the sky, they were devised by the Greeks, who, enjoying a warm climate, used to cover their houses with them; but where the rain waters freeze, pavements of this sort are not to be trusted. To make a terrace of this sort, it is necessary to lay two courses of boards, one athwart the other, the ends of which ought to be nailed, that they should not twist nor warp; which done take two parts of new rubbish, and one of tiles stamped to powder; then with other three parts of old rubbish mix two parts of lime, and herewith lay a bed of a foot thickness, taking care to ram it hard together. Over this must be laid a bed of mortar, six fingers thick, and upon this middle couch, large paving-tiles, at least two fingers deep. This sort of pavement is to be made to rise to the center in the proportion of one inch and a-half to ten feet. Being thus laid, it is to be planed and polished diligently with some hard stone; but, above all, regard is to be had that the boarded floor be made of oak. As for such as do start or warp any way, they be thought naught. Moreover, it were better to lay a course of flint or chaff between it and the lime, to the end that the lime may not have so much force to hurt the board underneath it. It were also well to put at the bottom a bed of round pebbles.
APOLLO CHARMING NATURE.[ToList]
And here we must not forget another kind of these pavements which are called Græcanica, the manner of which is this: Upon a floor well beaten with rammers, is laid a bed of rubbish, or else broken tile-shards, and then upon it a couch of charcoal, well beaten, and driven close together, with sand, and lime, and small cinders, well mixed together, to the thickness of half a foot, well leveled; and this has the appearance of an earthen floor; but, if it be polished with a hard smooth stone, the whole pavement will seem all black. As for those pavements called lithostrota, which are made of divers colored squares or dice, they came into use in Sylla's time, who made one at Præneste, in the temple of Fortune, which pavement remains to be seen at this day.
It may be remarked here, that the Roman villa at Northleigh, in Oxfordshire, examined and described by Mr. Hakewill, abounded with beautiful pavements. The substratum of one of these, which had been broken, was investigated, when it was found that the natural soil had been removed to a depth of near seven feet, and the space filled up with materials which bear a near resemblance to those which Pliny recommends.
A specimen of the coarser sort of mosaic pavement is to be seen in the Townley Gallery, in the British Museum.
