Page:Popular Science Monthly Volume 19.djvu/852

832 less." The departments of the Upper and Lower Alps actually lost thirty thousand inhabitants, or one ninth of their population, between 1851 and 1876. A law for recovering the mountains with wood, which had been prepared by M. Forçade de Rouguet, director-general of the administration of the forests, was adopted by the legislative bodies in 1860, and was put in operation shortly afterward.

In some cases, the work of planting woods is left optional, but is encouraged by the offer of rewards to the communes or individuals who undertake it. In other cases, where the public interest is at stake, the state determines the area of land to be planted, and allows the proprietors to perform the work if they will; if they refuse to do so, it attends to the matter itself, taking care that its proceedings shall be as inoffensive to the people as they can be made, and be at the same time effective.

The first question that is presented in dealing with a hill that has been cut up with ravines is to determine the perimeter of the lands to be restored. The area should not be limited to the banks of the torrent and its branches, for these banks, being continually undermined and always changing, would continue, by giving way, to enlarge the basin if they were not themselves fixed by vegetation. The justice of the rules which M. Surrell laid down on this point in 1841 has been confirmed by experience. We should begin, he said, to trace along either bank of the torrent a continuous line which shall pursue all the inflections of its course, from its remote origin till it issues from the gorge upon the lower valley. The tract included between each of these lines and the crest of the banks would form what I would call a zone of defense. The zones of the two banks would meet at the upper end, following the contour of the basin, and would thus surround the torrent, like a belt, in its whole extent. Their width, which should vary with the degree of the slope and the consistency of the soil, may be as little as fifty yards at the lower end, but should increase rapidly as the zone rises up the mountain, and should end by including spaces of five or six hundred yards. This delineation is applicable not only to the principal branch of the torrent, but also to the secondary torrents that empty into it, and to the smaller ravines departing from each of these torrents, and thus, pursuing one branch after another, should not stop till it reaches the source of the most remote rill. As these zones of defense go on enlarging up the mountain, they will join, and even merge into each other toward the summit, so as to form a continuous band around the upper part, leaving no void in it.

The perimeter of the land to be rewooded having been determined, the next step is to prohibit pasturage, in order to prevent further disintegration of the soil by the feet of the sheep, and allow the grass to recover. The ultimate result is assisted by cutting the bushes down to the stump, and planting willow-cuttings in horizontal rows about two yards apart, to hold the earth on the almost vertical slopes, and