Читать книгу Inventors at Work, with Chapters on Discovery - George Iles - Страница 68

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Inventors have taken a hint from nature as she carries a burden of mud and pebbles in a rapid stream of water. A modern method of deepening a water course is to reduce to fine silt the surface of its bed, and then remove this silt with a powerful stream. Water in swift eddies both lifts and bears away not only clay, but stone and gravel when these are small enough. In placer-mining streams of water much more powerful are directed against hill-slopes of earth and stone, which disappear a great deal faster than by means of spades and shovels. One of our Northwestern railroads runs for some miles along the base of a steep ridge, from which at times heavy rains wash down masses of earth, sand and gravel to the track. A powerful steam pump forcing a stream through hose removes the obstructions from the line with amazing rapidity. Work a good deal commoner and vastly more important consists in taking a process begun by nature and carrying it many steps further, so as to break up masses of earth again and again. The plow, the harrow, the sharp-toothed cultivator, divide and subdivide the soil of farm and garden so as to offer rootlets new surfaces at which rain may be drunk in with its nourishing food. When a garden patch is to be fertilized by bones, these serve best when reduced to meal, so as to be quickly and widely absorbed.