Chap. IV.

ROMAN.

113

"1

fr

alternately placed square and jutting out, the better to unite them with the adjoiningmasonry; almost all the latter formed the thickness of the walls, within which'werethe pipes. The upper bed of eachstone, 6 inches round the opening,is cut in the form of an invertedcone, as is the lower bed, the otherpart of the bed being level : allthese beds or joints, being placed onewithin the other, formed an ascend-ing joint 2 inches in height, and pre-vented any filtration of water into thebody of the masonry. These drainscarried off all the urine and rain water.

A hole, 2 inches in diameter, sunkin the middle of a stone, slightlydished, formed the entrance of allthe drains of the lower stories, fromwhich it is concluded they were usedfor a similar purpose. Besides theupper openings of these fifty-sixdrains, in the landings above the gal-lery of the first story, there was asimilar number, and also in the pas- Fig. 127. drains.

sages of communication with the two corridors of the ground floor; they are at 1 foot 9inches above the ground, and might serve to cleanse the issue of the gargouille whichpoured forth the waters into the outer aqueduct.

The drains communicated by a gutter or channel offreestone to a well or cesspool, 2 feet 4 inches in dia-meter, under the stairs of the ground floor, in themass of masonry which supported them; the bottomof this well communicated with a small aqueduct, 13inches wide by 18 high, having a considerable fall,the lining formed with the greatest care in moellonand mortar : the base and covering being executed withlarge stones. This aqueduct conducted diagonallyto the middle of the under side of the stairs, where itunited with that of the corresponding drain; at thispoint the two emptied themselves into one of 18inches in width by 22 in height, the issue of whichwas made under the pavement of the exterior corridor,in the centre of the portico, which carried the greatstairs of the lower floor, and at 3 feet below the pave-ment of this same gallery: this issue was formed bya large stone, so placed against the covering of theaqueduct, that at the two sides a passage was left forthe water. The external gallery of the ground floor,under which the drains discharged themselves, and allthe passages which communicated from the two gal-leries, were entirely filled up with chippings of largepieces of freestone, from the level of the foundations,to within 6 inches below the plinths. This latterheight was occupied by an inclined floor of cement,serving as a pavement to the two corridors as well asthe other passages. The waters easily filtered throughthin chippings of freestone, and the humidity anddisagreeable odour was prevented from affecting thegalleries, by the interposition of the bed of cementwhich covered these fragments. The water and urineran off by infiltration into the drains, which couldonly serve for the purposes indicated, particularly astheir entrances, still preserved in the vomitories of thefirst and second precincts, are only an inch and aquarter in diameter.

Sixty-four other drains, found in the passages of the Fi S- 12 $*vomitories of the first and second precinct, corresponding with the interior gallery of theground floor, were for the same purpose. A drain placed on each side of the set-off ofthese passages, with a hole 2 inches in diameter, formed in freestone, slightly dished out.

T

UPRIGHT DRAINS.