^{page 41 note a} The richly illustrated folio volumes of Canina are simply works of imagination; and worse than useless to the real student. Almost the same might be said of the handsome work by Choisy, L'art de bâtir chez les Romains.

^{page 43 note a} There is no truth in the statement that these tufa blocks were split with wedges: many of them bear distinct marks of chisels from a quarter to half an inch in width. Tufa is not laminated in structure, and a wedge only shatters it to pieces.

^{page 44 note a} A wonderful example of the perfect jointing of peperino blocks can be seen in the recently exposed angle of the podium of the Temple of Faustina, near the bottom, where accumulations of earth have preserved the surface ever since its marble lining was torn away. Here the beds and joints are so close as to be imperceptible except with the closest examination.

^{page 44 note b} The Roman foot was about a quarter of an inch shorter than an English foot.

^{page 45 note a} Mommsen is mistaken in his assertion that travertine is employed in the barrel vault of the Cloaca Maxima: see Middleton, Ancient Borne in 1885, p. 76.

^{page 53 note a} The tops of old walls in Rome are now often protected by a covering of square bricks made to look like old ones, and this gives the wall a delusive appearance of being formed of solid brickwork.

^{page 53 note a} This column now stands in the piazza at the east end of S. Maria Maggiore, forming the pedestal of a very poor statue of the Virgin.

^{page 53 note a} As for example in Nero's Aqueduct for the Aqua Claudia, and in the great hemi-cycle of shops in Trajan's Forum.