and it would not be difficult to give additional examples. Before proceeding to a minute description of the principal objects of interest outside the church, we may say a few words about the =walls=, which, however, have been so patched and repaired in successive ages, that they have lost all signs of uniformity. The thickness of the walls is, on an average, about 2 ft., and this dimension is noticeable, because we meet with it over and over again in Roman villas. The materials, too, are similar, and resemble what have been found in villas--a mass of rather rough walling, partly of brick, partly of stone, evidently intended to be plastered on both sides, and, to a great extent, built with hard "sea-shore" mortar. This mortar is composed of pebbles, small shells, etc., and is of such remarkable solidity and strength that, although the walls of the church are thin and lofty, they have sustained without any injury, and with comparatively low buttresses, the thrust of a high-pitched Gothic roof. It was not uncommon for churches to be erected on the site of, and using part of the structure of, Roman secular buildings, or temples. And we give for what it is worth the opinion of Mr Roach Smith, an experienced antiquary, who gave special attention to Roman work, and who states in a letter written on January 6, 1883: "There are many examples of churches being built upon the remains of Roman buildings, no doubt often _temples_, and not unfrequently of a small size. Some instances are very remarkable, as that of Britford, near Salisbury, at old Verulam, etc. I have ever had a belief that St. Martin's Church is founded upon, or built upon, or built into, a Roman temple." The walls of the church form an interesting study, not only for their venerable aspect, but also for their irregularity. The brick courses in the =Nave= are pretty general throughout, sometimes at 9 inches apart, sometimes as much as 20 inches, or even more. A great deal of old plaster is found externally in the middle of the south wall of the _nave_, and there are masses of Roman bricks congregated at the east and west ends of the same wall (the angles of the walls in public buildings being often composed entirely of bricks); and we find also, in parts, large blocks of grey stone, as well as pieces of travertine, tertiary sandstone, Kentish rag, red sandstone, Purbeck marble, chalk, and many other geological specimens. Here and there, interspersed with Roman bricks, are patches of "chequy" masonry, the stones being placed at wide intervals, notably on the south-east corner, and on the north side.