h. Line of the profiles of ancient tufa piers of arches. (These are represented by dotted lines only, as if transparent, to shew the consoles of the Flavian Emperor inserted in them.) i*. Line of second arcade of tufa. A. Plan. B. Section. The same letters of reference are used in the plan of this section. THE COLOSSEUM. PLATE XIX. VIEW IN PART OF THE SUBSTRUCTURE, WITH PLAN AND SECTION. [Illustration: VIEW IN THE SUBSTRUCTURES.] DESCRIPTION OF PLATE XIX. VIEW IN PART OF THE SUBSTRUCTURE, WITH PLAN AND SECTION. E E. The consoles. F F. The podium. a. Entrance to the descent to feed the animals. b. One of the dens. c. The stream of water in front of the dens. f f. The sockets for pivots for the capstan to work in. g g. The original pavement. h h. Piers of tufa in front of the dens. k k. Long and lofty chamber under the gallery, in which are seven sockets for the pivots of the capstan to work in. y. Mouth of the great drain, with the iron grating. z. Site of the sluice-gate, and groove for it to work in, as a portcullis. A. The Plan of this part. B. The Section of it. THE COLOSSEUM. PLATE XX. PORTION OF THE SUPERSTRUCTURE IN THE PRINCIPAL GALLERY. [Illustration: PORTION OF THE SUPERSTRUCTURE IN THE PRINCIPAL GALLERY.] DESCRIPTION OF PLATE XX. PORTION OF THE SUPERSTRUCTURE IN THE PRINCIPAL GALLERY. A A. Walls of brick, dividing the different bays of the gallery. B B. Arches of construction, to make the brick facing adhere better to the mass of tufa concrete behind it. C C. A void space from which a pier of travertine has been carried away for building purposes[249]. D D. The great pier of travertine on one of the arches of the corridor of the Flavian Emperors. THE COLOSSEUM. PLATE XXI. VIEW IN THE UPPER PART. DETAILS. [Illustration: COLOSSEUM DETAILS IN UPPER PART] DESCRIPTION OF PLATE XXI. VIEW IN THE UPPER PART. DETAILS. A A. Piers of the great corridor. a a. Aperture from which a pier of travertine has been removed for building material, by the Barberini (?). b b. Wall of brick, with arch of construction standing equally well without the support of the travertine pier. c c. Wall of tufa, of a lower storey. d d. Vault of a third storey, below. e e. Remains of the vault of the stairs to the upper storey. f f. Floor of the second corridor. g g. Floor of the principal gallery. The object of this plate is to make it still more clear that the brick arches of construction did not _really_ rest on the piers of travertine, although at first sight they appear to do so. The Roman bricks of the first century are two feet square and one inch thick, but in these arches they are cut down from two feet to three or four inches at the impost, or springing of each arch, just where the greatest strength would have been required. They have evidently been cut through to admit the stone piers, which were required to carry the upper gallery, when that was built of stone instead of wood. THE COLOSSEUM.