Roads, which were formerly of the utmost importance as the only means
of communication between distant places, and on which an enormous
amount of labour and capital have been expended, are now becoming
rapidly subordinate to railways; however this may be, it is quite
clear that roads can never be superseded by the latter. The numerous
streets of great towns are so many short roads, and on some of them
the amount of traffic is so very great, that the utmost skill of the
engineer is required to resist the consequent wear and tear.
The Roman roads, which have been the means of civilisation to the
greater part of Europe, were constructed in a very solid and durable
manner, by first laying down a layer of rough stone set in cement,
and upon this, stones either squared or nicely fitted together and
also cemented; the whole formed a solid mass of masonry, not unlike
the wall of an old castle laid horizontally. Basalt (a volcanic
product) was the stone used for this purpose, where it could be
procured. These roads were generally raised above the surrounding
ground, but excavations, bridges, and tunnels were made where these
were found necessary to continue the road in a direct course.