=The Decoration of the Vaults.=--The floors of the corridors are laid in mosaic of varying patterns. The ceilings are uniformly a barrel vault, with pendentives--the same, that is, as those of the North, East, and South Corridors below. The vaults are covered with a painted decoration of Renaissance ornament which for variety and interest is hardly surpassed anywhere else in the building. The decorative scheme which has been adopted was planned throughout by Mr. Casey, and elaborated, especially in the matter of color, and carried into effect, by Mr. Garnsey, working under Mr. Casey’s direction. In addition, each corridor contains, as a distinctive accent of color and design, a series of paintings by a specially commissioned artist--in the West Corridor by Mr. Walter Shirlaw, in the North Corridor by Mr. Robert Reid, in the East Corridor by Mr. George R. Barse, Jr., and in the South Corridor by Mr. Frank W. Benson. In the side corridors, also, at the west end, the arch of the vault is spanned by a broad band of stucco ornament containing a series of octagonal coffers, ornamented in relief by Mr. Hinton Perry. The decoration is varied, of course, from corridor to corridor, in order to prevent any monotony of impression, but the main principles on which it is based are everywhere the same. Thus the color scheme--which was suggested in part by the beautiful Library in Sienna--comprises in every corridor blue in the pendentives, golden yellow in the penetrations, and a grayish white in the body of the vault. The only exception to this rule is in the West and East Corridors, which are terminated by double arches instead of ending directly upon a wall. Here the end penetrations are red and the pendentive yellow. The others remain as before. The delineation of the spaces is at bottom very simple, and though more elaborate, a good deal like that already noted in describing the mosaic in the lower corridors. The penetrations are outlined by a bright colored border, on which, where the lines converge to a point at the top, rests a border of greater width, enclosing the entire vault in a single great rectangle. This, in turn, is divided into compartments by bands of ornament, varying in number according to the requirements of the decoration, but always occurring immediately over the columns of the arcade. These bands, coming where they do, perform a vital service for the decoration in continually reminding the visitor, if only by a painted arabesque, of the importance of the arch in such a piece of construction as a vault. In the spaces between them are garlands and wreaths, and panels for paintings and inscriptions--the whole making part of one great arabesque, which is as easily intelligible and coherent as it is various, but which would have been bewildering in its wealth of ornament and color if it had not been for the fundamental service performed by these various bands and borders and broad masses of color.