Page:Historic highways of America (Volume 15).djvu/137

 the prepared roadbed. Such material is usually carried upon a road in wheelbarrows or dump carts, and then spread in even layers with rakes, but the latest and best device for this purpose is a spreading cart.

If a roller cannot be had, the road is thrown open to traffic until it becomes fairly well consolidated; but it is impossible properly to consolidate materials by the movement of vehicles over the road, and if this means is pursued constant watchfulness is necessary to prevent unequal wear and to keep the surface smooth and free from ruts. The work may be hastened and facilitated by the use of a horse roller or light steam roller; and of course far better results can be accomplished by this means. If the gravel be too dry to consolidate easily it should be kept moist by sprinkling. It should not, however, be made too wet, as any earthy or clayey matter in the gravel is liable to be dissolved.

As soon as the first layer has been properly consolidated, a second, third, and, if necessary, fourth layer, each three or four inches in thickness, is spread on and treated