The originators of many great reforms in law and religion, in working to establish principles applicable and needful to local issues, have thereby, unconsciously to themselves, established principles which have proved beneficial and applicable to the whole human race. In the stress of trying times we have discovered in the constitution of our country latent powers which its framers never dreamed were there. Thus it is with the humble occupation of road-building. A road constructed for the convenience of some primitive community or to gratify the caprice of some rich man or lordly ruler becomes often in after years an Appian Way for public travel and commercial intercourse.
A road may be located in one of three ways. It may be laid out in a straight line by crossing lowlands in the mud and going over hills at steep grades. The ancient Britons, like the early settlers in this country, established their homesteads and villages on commanding situations, and ran their roads and bridle-paths in direct courses by their habitations. The Romans, possessors of great wealth and abundant slave-labor, built their military and public roads in direct lines from place to place, regardless of expense. In this way they shortened distances somewhat, but their roads must have been constructed at enormous expense in money and labor. Their roads were marvels of engineering skill and workmanship, which even now, after the lapse of eighteen centuries, impress every thoughtful observer with the idea that he is in the presence of the work of the immortals. They threw arched bridges of solid masonry over rivers and across ravines; they cut tunnels through mountains, and sometimes carried their roads underground for the sole purpose of shelter from the sun; they levelled heights and made deep cuts through hills; and when they came to a marsh they built a causeway high enough and strong enough to make it safe and dry at all seasons of the year. This mode of location is still followed in the Latin countries of Italy, France, and Spain, where many of the roads are identical with the old Roman roads.
The other mode of locating a highway is to seek the best attainable grade the country will permit of by winding through valleys and around and across hills. There is obviously one advantage to a perfectly straight road between two places: it is the nearest route. But this is about the only advantage a straight road has over a curved one. In a hilly country a straight road is frequently no shorter than a curved one, because the distance around a hill is generally no greater than over it, as the length of a pail-handle is the same whether it is vertical or in a horizontal position. In an uneven country a straight road with anything like the same grade as the curved road can only be constructed at enormous and unnecessary expense and labor. Even in a level country a road curved sufficiently to give variety of view and to conform to Hogarth's "line of beauty" is preferable to a perfectly straight road, which is always tedious to the traveller.
"The road the human being travels,
That on which blessing comes and goes, doth follow
The river's course, the valley's playful windings,
Curves round the corn-field and the hill of vines."
Moreover, we are told by competent engineers that the difference in length between a straight and a slightly curved road is very small. Thus, if a road between two places ten miles apart was made to curve so that the eye could nowhere see farther than a quarter of a mile of it at once, its length would exceed that of a perfectly straight road between the same points by only about one hundred and fifty yards.
But, in any event, in road-making mere straightness should always yield to a level grade, even if thereby the distance is greatly increased; for on a good grade a horse can draw rapidly and easily a load which it would be impossible for him to draw on a steep grade. It is an accepted maxim by road-engineers that the horizontal length of a road may be advantageously increased, to avoid an ascent, by at least twenty times the perpendicular height which is to be thus saved; that is, to escape a hill a hundred feet high, it would be proper for the road to make such a circuit as would increase its length to two thousand feet.
Hence it is apparent that the ordinary road in a hilly and uneven country should follow the streams as far as possible, as Nature has located them in the places best adapted for highways; and when hills are found on the line of a road they should be surmounted by passing around and across them at the easiest grades possible rather than over them at steep grades.