Quotation from: General ScienceWritten by: Bertha M. Clark |
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The more intelligent races among men soon learned to help themselves in these tasks. For example, our ancestors in the field soon learned to pry stones out of the ground (Fig. 91) rather than to undertake the almost impossible task of lifting them out of the earth in which they were embedded; to swing fallen trees away from a path by means of rope attached to one end rather than to attempt to remove them single-handed; to pitch hay rather than to lift it; to clear a field with a rake rather than with the hands; to carry heavy loads in wheelbarrows (Fig. 92) rather than on the shoulders; to roll barrels up a plank (Fig. 93) and to raise weights by ropes. In every case, whether in the lifting of stones, or the felling of trees, or the transportation of heavy weights, or the digging of the ground, man used his brain in the invention of mechanical devices which would relieve muscular strain and lighten physical labor.
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