DEGREE OF DURABILITY OF WALLS
(a) As may be seen by anyone inspecting the walls, as well as on perusing the published description of many ruins of the earliest types, the elliptical and curved form of building has proved the most durable. In many instances the elliptical structures are more or less intact, while the angular and less skilfully built additions, extensions, and alterations of a later period have largely become ruinous and chaotic.
(b) This is accounted for by the more excellent workmanship in the construction of the ruins of the elliptical type, which have far broader foundations, are more massive, have a decided batter-back both inside and outside, bonded courses, the blocks of each course being more carefully selected, and the summits tied with “throughs,” while the angular type of ruins, with their plumb walls built on straight lines, with independent faces either side and carelessly filled-in interiors, and a less superior workmanship, have caused these walls to suffer more than the older type of ruins.
(c) Walls built on curved lines are in a far better state of preservation than those built on straight lines, the curves having served to strengthen the walls.
(d) Rounded ends of walls and rounded buttresses have proved to be far more durable than angular ends or squared buttresses, though most of these latter erections are obviously of a later date.
(e) The portions of divisional walls near main walls are in a better state of preservation than the other portions which are in the open parts of the ruins. This is owing to the protection and support of the larger walls. Many of the divisional walls are practically independent, and therefore more liable to collapse, but if not independent the number of entrances passing through them practically makes them such.