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Show Vi va V".-.j,,n?"V. fMv. '' s &VL feT t CM . , ., j MEMBERSHIPNo. 1531. When John Louden Macadam, in 1810, began to experiment with broken brok-en stone for building roads, he met with much opposition from the "standpat" road builders, who con tended that the expense would be prohibitive pro-hibitive and that anyway, broken stone in courses of assorted sizes was no better than broken stone of one size in one course. Time proved the merit of Macadam's Macad-am's idea, although the century and nine years which have elapsed since his first practical experiment was tried at Bristol, England, in 1815, have greatly altered the practice of macadamized road building. Up to the advent of the automobile, Macadam's principles were employed in their entirety, the broken stone being bonded with rock dust and water, the former replaced by the impact im-pact of iron shod vehicles and hoofs, the latter by the rain. When the automobile, with its rapid movement and broad rubber tires, sucked the rock dust from between be-tween the stones in spite of the gentle bonding effort of the water, it was realized that something was lacking in. the roads used for fast, soft-shod traffic, which lack was not felt under slow and steel-shod trajffic. That "something" was a better bond than water. It was found in oils and tars and bituminous compounds. Luckily for the millions of dollars invested in macadamized roads, an oil, tar, or bituminous binder could, and was, applied ap-plied with success to existing roads, thus saving to the taxpayer miles of highways which were otherwise doomed. ' Today, all macadamized roads are built with the bituminous oil or tar binder applied during the building, but the basic principles of larger foundation and smaller upper course, topped by a wearing surface of fine crushed rock and dust, bound in place by something, is still employed. Macadam's Ma-cadam's greatest monument is the dropping of the capital letter in his name and making it the label for all roads built of crushed rock laid in courses of different sizes. |