ROADS, are pathways formed through a country, by which passengers and com modities may travel, or be transported, with more or less facility and expedition, from one place to another. Roads are of various kinds, according to the state of civilization and wealth of the country through which they are constructed, and according to the nature and extent of the traffic to be carried on upon them, from the rude paths of the aboriginal people, carried in direct lines over the natural surface of the country, passable only by foot passengers or pack-horses, to the comparatively perfect modern road, car ried on an artificial causeway, and re duced to a nearly level surface at enor mous expense by means of vast excava tions, extensive embankments, bridges, viaducts, tunnels, and other expedients supplied by the skill and ingenuity of the civil engineer.
Advantages of Roads.There is no ex pedient which more powerfully conduces to the advancement of a people in civiliza tion, or to the extension of their pros perity and national wealth, than the con struction of good roads, connecting the various centres of commerce and of in dustry about which they may have col lected themselves. The invention of printing, the expedient of money, the adoption of a unitbrm system of weights and measures, would severally be ineffec tual, or productive of advantages of a very limited extent, if the intercommu nication of those whose feelings and ideas are expressed and conveyed in print, and among whom money is made to cir culate, and whose commerce is stimulat ed and facilitated by the uniform module of quantity supplied by weights and measures, were not facilitated and expe dited by the means of conveyance sup plied by roads. Without roads, the in terchange of advantages, moral, intellec tual, and physical, which now takes place in all highly civilized countries between the rural and the urbane population, could not be maintained ; without them, indeed, large towns or cities could not continue to exist. The supply of the population collected in such places, with the various products of agriculture, ne cessary to their physical existence, could not be sustained. Nor, on the other hand, would the rural population afford ing that supply be benefited by a return in exchange of the refinements of the town, and the various articles of luxury and necessity obtained by commerce from every part of the globe.
But roads are not less necessary for the. advancement of agriculture itself, than for the due maintenance of the necessary relations between the towns and the country. Without the aid of roads, it would be impossible to applythose arts to the soil by which increased powers of production are given to it. Without roads, the various kinds of manure, by which the scientific farmer knows how to raise augmented crops, could not be trans ported to his fields from the place, often distant and difficult of access, where such manures are found. Roads may then, in fact, be considered as a system of veins and arteries, by which all those plea necessary for the maintenance of the prosperity of a country are kept in circu lation.
The Art of Roac1=naA:ing.—When it is proposed to construct a line of road ex tending between two places, the engineer upon whom such a duty' evolves, first makes himself well acquainted with the surface of the country lying between the two places, so as. to obtain an acquaint ance with the face of the country, some what approaching to that which would be supplied by a superficial model of it, which would exhibit all its inequalities and undulations of surface. Iie is then to select what he considers, all circum stances being taken into account, the best general route for the proposed road. But, previously to laying it out with ac curacy, it is necessary to make an instru mental survey of the country along the route thus selected; taking the levels from point to point throughout the whole distance, and making borings in all places where excavations are required, to deter mine the strata through which such cut tings are to be carried, and the requisite inclinations of the slopes or slanting sides, as well of the cuttings as of the embankments to be formed by the mate rial thus obtained. It is also requisite, in the selection of the route for the propos ed road, to have regard to the supply of materials, not only for first constructing it, but for maintaining it in repair ; thus, the position of gravel pits and quarries in the neighborhood of the proposed line, and the modes of access to them, should be well ascertained.