Chap. IV.

HOMAN.

116

of the first precinct, and the foundation of the parapet wall of the second, arrived at the greatcircular inner aqueduct. Twelve of these discharges sufficed for carrying off the water ofthe first precinct, which was only composed of four rows of seats.

The second being protected like the first by a parapet, the same method for dischargingthe water as those already explained was adopted, this second precinct receiving also thewater from the cornice of the attic. Twenty-four discharges at the level of the step of thisprecinct carried the water behind the wall of the second podium, and through the middle ofthe vault which covered the chamber through which the great circular aqueduct passes. Atthe summit of this vault, against the wall of the second podium, a large stone pierced witha hole four inches in diameter received the collected waters. These holes have led some topresume that they received the posts intended to support the tent which covered the amphi-theatre. Their nearly horizontal position, and their conical opening, at once show theirdestination.

The water which fell on the arena and seats of the amphitheatre was conducted into twocircular aqueducts, that of the arena, and that of the interior. The latter, which followedthe contour of the building, is 30 inches wide; its base, on the same general level asthe foundation, is formed of two walls, faced with dressed stone 6 feet 6 inches high,having its course through the chambers which receive the water of the first and secondprecinct: it is arched in the thickness of each wall, under the issues of the vomitories ofthe first and second precinct, corresponding to the inner gallery of the ground floor, andunder the passages of the north and south doors. It also communicates with, and emptiesitself into, the aqueduct of the arena, under the two great passages of the east and westdoors, by two square openings, 30 inches wide by 20 inches high. The aqueduct underthe great east and west passages is covered with large landings resting on walls built oneach side.

The inner aqueduct received all the water which fell through the openings of the thirty-two vomitories of the first and second precinct, the entrances of which corresponded to theinner gallery of the ground floor. This water, which during storms is abundant, was stoppedon the landing of the passage of each vomitory by a step whose tread was hollowed out to adepth of half an inch. A hole two inches in diameter, opened at each extremity of this stepin the recesses of the vomitories, served as a urinal, as well as received the rain water, andthen passed into the aqueduct immediately below. By this means the water falling throughthe openings of the vomitories could never come into the inner gallery on the ground floor.

The rain water driven by the wind into the outer gallery of the ground floor through theopenings of the sixty arches of the facade would soon have inundated this gallery if meansbad not been provided for getting rid of it by a rapid and successive discharge. The pavingof the outer gallery, and that of all the passages of communication, had a fall of 6 inchestowards the inner gallery, so that the rain which the wind blew into the outer gallery ran intothe second. At the foot of the piers which divide the passages of the vomitories, it metwith a discharge into a small aqueduct, which conducted it into the great inner circularaqueduct: the smaller opening into the larger by a hole 3 feet high, 18 inches wide, and Hiinches above the base of the great aqueduct. A similar discharge remains in the middleand at the foot of the first step of the great staircases, which admits under the paving of theouter gallery, a part of the waters of this same gallery.

The inner circular aqueduct received all the water of the seats and steps from the attic tothe podium, that of the thirty-two vomitories whose entrances corresponded to the innergallery of the ground floor, and that which the wind carried into the outer gallery throughthe openings of the entrance porticoes : all this water united formed a considerable quantityduring storms; but it was so divided, and so well directed, that it was impossible anystoppage could take place, or that it could ever inundate the galleries and passages, muchless injure the solidity of the masonry. By such means the Roman engineers, who weremasters in the art of construction, effectually drained the upper galleries and vomitories.

The inconvenience arising from the chance of the water penetrating into the passages andgalleries through the openings of the thirty-two vomitories of the first and second precincts,was obviated at all the upper stages to which the issues of the other vomitories correspond,the same pains being taken to get rid of it quickly. The gallery of the half story of thefirst floor could easily be inundated by the openings of the thirty-two upper vomitories ofthe second precinct, to which this mezzonine gallery was solely destined, but the first stepof the stairs of each vomitory was slightly hollowed and pierced in the middle with a verticalhole, an inch in diameter. Below this step and hole is a stone cut in the form of a cistern5 inches deep, 12 long, and 8 wide. At the end of this cistern is a gargouille 4 incheswide, closed at one extremity, and pierced with a perpendicular hole. The pavement of thehalf-story gallery, which throughout is tooled, is formed opposite each vomitory by astone similar in all respects to the tread of the first step of the staircase of the vomitory :this is slightly hollowed and pierced with an aperture which corresponds with a small holemade through the vault, which carries the inclined winder and the second revolution of thegreat staircase of the ground floor. The water which fell in the passages of the vomitories, on

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