“Ye toppling crags of ice, Ye avalanches, whom a breath draws down In mountainous o’erwhelming.” The cutting away of trees, at one time a common cause of avalanches, is forbidden by a federal law: “Altdorf long ago had been Submerged beneath the avalanches’ weight, Did not the forest there above the town Stand like a bulwark to arrest their fall.” There is a distinction between summer and winter avalanches. The former are solid avalanches formed of old snow that has acquired almost the solidity of ice. The warmth of spring softens it, loosens it from the rocks, and it slides down into the valleys; these are called “melting avalanches,” and they regularly follow certain tracks which are embanked like the course of a river with wood or bundles of branches. The most dreaded and terrible avalanches--those of dry powdery snow--occur only in winter, when sudden squalls and hurricanes of snow throw the whole atmosphere into chaos. They come down in sudden whirlwinds, with the violence of a waterspout, and in a few minutes work great destruction. The most memorable avalanche in Switzerland occurred in 1806, when one of the strata of Mount Rossberg, composed of limestone and flint pebbles, nearly three miles long, one thousand feet broad, and one hundred feet thick, precipitated from a height of three thousand feet and annihilated the three prosperous villages of Goldau, Busingen, and Lowerz, and killed four hundred persons. Enormous blocks, some of them still covered with trees, shot through the air as if sent from a projectile or tossed about like grains of dust. In 1501 a company of soldiers were swallowed up by an avalanche near the St. Bernard. At Fontana, in the Canton of Ticino, in 1879, the church and town-hall were destroyed and many lives lost. On this occasion, within a space of five minutes, no less than three hundred and fifty thousand cubic metres of earth and rock came down from a height of four thousand three hundred feet. In the same year an avalanche came rushing down the westerly slope of the Jungfrau into Lauterbrunnen valley, a distance of about seven thousand feet. Its peculiar feature was that, not only along its course, but even on the opposite side of the valley, twelve hundred feet away, the atmospheric pressure, which its rapid movement generated, was so great as to level entire forests. In the Rhone valley, in 1720, a single avalanche destroyed one hundred and twenty houses at Ober-Gestalen, killing eighty-eight persons and four hundred head of cattle. The victims were buried in a trench in the churchyard, where an inscription, still existing, records the event in these words: “God! what a grief, eight and eighty in one grave!” In the Grisons, the whole village of Selva was buried, nothing remained visible but the top of the church-steeple, and Val Vergasca was covered for several months by an avalanche one thousand feet in length and fifty in depth.