ROADS AND ROAD-MAKING. Roads form a primary element in the material advance ment of a nation, being essential to the development of the mann] resources of the country. Canals and railways have no doubt, in modern times, superseded to some extent the common highways; still these retain their importance were it only as essential auxiliaries.
The Romans-were great constructers of roads, and regarded them as of vital impor tance for conquest and the maintenance of their empire. They are said to have learned the art from the Carthaginians. Except where some natural barrier made it impossible, the Roman roads were almost invariably in a straight line; probably because the chief means of transport then in use were beasts of burden, and not wheeled vehicles, which made the preservation of the level of less consequence. The substantial character of the Roman roads is well demonstrated by the fact that they have in some instances borne the traffic of 2,000 years without material injury. The plan of construction was pretty uniform, being that described in the article on the APPIAN WAY, one of the earliest and most famous of them. They varied in breadth from 15 to 8 ft., and had often raised footpaths at. the sides and blocks of .:tones r./1 intervals to enable travelers to mount on horseback.
The roads made by the Romans in Great Britain gradually fell into decay, and the attempts that were-now and then made to repair them were institheie»t to prevent Eng land falling into a worse state with respect to its highways than most other European countries. In 1285 one of the earliest laws on the subject of roads was passed. It directed that all trees and shrubs be cut down to the distance of 200 ft. ou either side of roads between market-towns, to prevent the concealment of robbers in them. The first toll for the repair of roads was levied by the authority of Edward III. in 1346 on roads which now form part of the streets of London. In 1555 an act was passed requir ing each parish to elect two surveyors of highways to keep them in repair by compulsory labor; at a later period, in place of the compulsory labor the " statute labor-tax" wzr.:; substituted. But long after this, the roads even in the neighborhood of London were wretchedly bad, and in tire other parts of the country they were still worse. For the
most part, indeed, they were mere horse-tracks; the chief advantage in following them being that they led along the higher grounds and so avoided bogs. These trackways were usually impassable in narrow, and in many places so deep and 'airy as to he liker ditches titan roads. So late as 1736 the roads in the neighborhood of Lou don were so bad that in wet weather a carriage could not be driven from Kensington to St. James's palace in less than two hours, and sometimes stuck in the anti altogether. Much curious information on the state of the roads and means of conveyance in England during the long period which elapsed from the decay of the Roman roads to the middle of the last century will be found in vol. i. of Smiles's Lives of Engineers.
In laying out a new line of road the skill and ingenuity of the engineer axe taxed to make the gradients easy with as little expense as possible in excavating and embanking (see EMBANKMENT), and to do this without deviating much from the direct course between the fixed points through which the road must pass. In order to do this an accurate survey of the tract, including the relative levels of its different parts and the nature of the strata, is a necessary preliminary. The formation of an extended line of road often involves the construction of extensive bridges, viaducts, and the like, which require the greatest engineering skill.
The importance of easy gradients or inclinations in roads is well understood in a gen eral way; but it gives a more precise idea of it to state that while, for example, the force requisite to draw a wagon weighing 6 tons along a level macadamized road is 264 lbs., on a road with an ascent of 1 in 70 the force required is 456 lbs., i. e., part of tons over and above 264 lbs. The greatest declivity which can be given to a road, so that horses may move down it with safety in a fast trot, varies according to its nature; for paved roads, 1 in 63—for those which are macadamized, 1 in 35—anti for those laid with gravel, 1 in 15, have been considered the limit.