[120] It is well known that the Romans constructed with great solidity, and maintained with constant care, roads diverging from the capital to the extremities of the empire. The good condition of these was thought to be of such importance, that the charge was only entrusted to persons of the highest dignity, and Augustus himself assumed the care of those in the neighbourhood of Rome. The expense of their construction was enormous, but they were built to last for ever, and to this day remain entire and level, in many parts of the world, where they have not been exposed to destructive violence. They usually were raised some height above the ground which they traversed, and proceeded in as straight a line as possible, running over hill and valley with a sovereign contempt for all the principles of engineering. They consisted of three distinct layers of materials; the lowest, stones mixed with cement, (statumen); the middle, gravel or small stones, (rudera), to prepare a level and unyielding surface to receive the upper and most important structure, which consisted of large masses accurately fitted together. It is curious to observe that, after many ages of imperfect paving, we have returned to the same plan. The new pavement of Cheapside and Holborn is based in the same way upon broken granite, instead of loose earth which is constantly working through the interstices, and vitiating the solid bearing which the stones should possess. A further security against its working into holes is given by dressing each stone accurately to the same breadth, and into the form of a wedge, like the voussoirs of an arch, so that each tier of stones spans the street like a bridge. This is an improvement on the Roman system: they depended for the solidity of their construction on the size of their blocks, which were irregularly shaped, although carefully and firmly fitted. These roads, especially in the neighbourhood of cities, had, on both sides, raised footways (margines), protected by curb-stones, which defined the extent of the central part (agger) for carriages. The latter was barrelled, that no water might lie upon it.—Gell.
[121] Knight.
[122] Knight.
[123] Knight.
[124] Brewster.
[125] Chambers.
[126] Anon.
[127] Chambers.
[128] Chambers.
[129] Anon.