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Page:Popular Science Monthly Volume 24.djvu/556

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THE POPULAR SCIENCE MONTHLY.

is so short that it does not become warm enough to be used with advantage. The same objection is alleged against snow-water. The glacier-water, however, which is exposed to the sun for hours while running down the flumes, reaches the fields at an agreeable temperature, and ready for immediate application. This water is here free from oxide of iron, and is entirely fertilizing; but additional richness is sometimes given to it by carrying it around through the barn-yards, and making it the means for transporting manure directly to the fields.

The chief canals which bring the water down from the mountains vary in length from one thousand to fifty-five thousand metres; or, measured by the time it takes the water to run through them, from a quarter of an hour to six hours. The total length of the canals in the canton is one million five hundred thousand metres, or two hundred and fifty hours. The skill with which they have been located and constructed excites an admiration that is increased when it is remembered that they date from a remote antiquity and are the work of a simple country-people. Beginning often in the immediate neighborhood of the glaciers, crossing treacherous hills and lofty precipices, and spanning deep abysses, passing through tunnels and cuts, led along artificial terraces, that sometimes require additional embankments or walls to support them, these canals are really formidable works. They furnish the life-blood of civilization to the canton, and stand for a capital of incalculable value. They have been built and are kept up by the villages; and a badly kept one is an exception.

In most of the valley-slopes they lie in groups of three or four, the uppermost one being the longest, and reaching far up toward the glacier-source, and have an average descent of about 0.5 per cent. The subordinate ditches are of a simpler character, till finally a mere mark on the ground is all that directs the water to the particular spot where it is wanted.

The application of the water begins at about the first of April in the valleys, and later as the height of the locality increases, till, on the highest cultivated grounds, it is delayed till the middle of June, and is continued for from two and a half to three months. The right to draw off the water is apportioned out by village officers into turns, of which there are from four to twelve in the season, of from eight to twenty-one days or more each, according to the number of land-owners claiming to share in it.

Among the most remarkable of the main aqueducts are those of the Gradetsch Valley, where the water is led down by eleven canals, the highest of which starts from an altitude of 2,300 metres, or nearly 7,500 feet above the sea. Some of the canals require wooden conduits three or four thousand metres long, that have at times to be supported by poles for six hundred metres at a stretch. To reach them for repairs the workmen have in some places to be let down the perpendicular rock-walls with ropes.