More recently a bath chamber has been found in Cannon Street built of tiles which on the illustration are indicated in alternate courses of red and yellow. In the description in _Archæologia_, it is remarked: “It would appear that the yellow was preferred, the red being employed where they were not visible.” Years ago Charles Knight observed that the tiles used in the City Wall at America Square varied from “bright red to palish yellow.” This has been confirmed by more recent accounts in _Archæologia_. Finally, Roach Smith, describing the discovery of a part of the South or River Wall of the City (_Archæological Journal_, vol. i.), says that the tiles used as bonding bands were straight and curved-edged (that is, flanged roof tiles), red and yellow in colour. At the Guildhall there are a roof tile and a flue tile of yellow colour. Building with tiles may for long have been customary, but the use of red and yellow tiles in the way described would probably have been a fashion during a limited time only, and in that case it follows that the buildings erected with red and yellow tiles are likely to be nearly contemporary; the date would, I suppose, be the fourth century. Specially made tiles were used for columns. At the Guildhall are several round tiles 8 in. diameter, suitable for the piers of a hypocaust. Also some semicircular tiles 12 in. in diameter. In Rochester Museum are some quadrants making up a circle about 1½ ft. in diameter. Tiles, eight of which made up a circle, have lately been found at Colchester, and in the Guildhall Museum is a course of a round column made up of twelve tiles around a small central circle. A large number of columns were evidently of such bricks plastered. [Illustration: FIG. 4. ] _Arches and Vaults._—The arches in the City Wall, where it passed across the Walbrook, described by Roach Smith, were of no great span (3¼ ft.). They were constructed of ordinary tiles and were of a roughly-pointed shape. Arches of this form were not infrequently used in Roman works; they were not the result of inaccurate building. About a dozen years ago a well-built pointed arch of alternate tile and tufa, found at Naples, was described in _Archæologia_. The tiles, although thin, were sometimes made slightly wedge-shaped, and the city gates at Silchester seem to have had arches of such bricks.