The oldest of the canals date unquestionably from pre-Roman times. The "Roth" Canal supplies three villages with water, and is 19,200 metres (more than eleven miles), or four hours and twenty-three minutes long. It starts from "La Plaine Morte" glacier, on the Weisshorn, 2,673 metres above the sea, crosses several clefts, is conducted through a tunnel more than three hundred metres long, is covered for 9,600 metres, exhibits other features of high engineering skill, has an average section of a metre and three tenths, and delivers nearly a cubic metre of water a second. An artificial lake, or reservoir, has been built in the same district, to hold the water that is not wanted for immediate use. Its water, however, has not the same value as that taken directly from the glaciers, because it has lost most of its mineral constituents by settling; but, as it has become thoroughly warmed, it is admirably adapted to those applications in which water is wanted simply to refresh vegetation, and make the soil more friable.
The villages of Ried and Bietsch have three aqueducts (Kehrwasser, Bietscherrinne, and Riederrinne), severally 8,400, 2,400, and 12,000 metres long, to bring down the muddy water from the great Aletsch glacier, which are led for long distances along vertical cliffs and over giddy chasms. At one point on the "Kehrwasser" three men have been killed, within twenty-five years, by falling into the gorge. The water of the Bietscherrinne issues foaming from a fearful-looking chasm. The canal, having a border formed of stones laid with sods, and masked by bushes from the Massa ravine that yawns beneath it, is safe to walk along at first. The bushes soon disappear, and the aqueduct becomes simply a wooden conduit, made of planks that have to be drawn to the place, and adjusted there with great danger, while the narrow, slippery gang-plank, which is the only walk, offers but the most precarious footing to one who has to look down through the high trestles or into the steep ravine of the wild Massa, on one side, while he must watch on the other side lest he hit his head against the overhanging rocks and lose his balance. The highest of the three canals, the Riederrinne, is distinguished from the others by its loftier rock-walls and deeper chasms. It reaches to the foot of the Aletsch glacier, and draws the water from its source. Near it may be seen older, abandoned canals.
Near where these three canals start is the Marjälen Lake, having its surface covered, even in summer, with floating ice. Its natural outlet is by the valley of Viesch into the Rhône, but occasionally, in seasons of extraordinarily high water, it overflows in the opposite direction, and pours its floods into the Massa, causing breaks in the canals and stopping the conveyance of water. The existence of the villages of Bietsch and Ried depends upon their obviating the mischievous effects of these overflows, and it is customary to give a pair of shoes to the mountaineer who first notifies the dwellers in the