1911 Encyclopædia Britannica/McAdam, John Loudon
McADAM, JOHN LOUDON (1756–1836), Scottish inventor, who gave his name to the system of road-making known as “macadamizing,” was born at Ayr, Scotland, on the 21st of September 1756, being descended on his father’s side from the clan of the McGregors. While at school he constructed a model road-section. In 1770 he went to New York, entering the counting-house of a merchant uncle. He returned to Scotland with a considerable fortune in 1783, and purchased an estate at Sauhrie, Ayrshire. Among other public offices he held that of road trustee. The highways of Great Britain were at this time in a very bad condition, and McAdam at once began to consider how to effect reforms. At his own expense he began at Sauhrie, despite much opposition, a series of experiments in road-making. In 1798 he removed to Falmouth, where he had received a government appointment, and continued his experiments there. His general conclusion was that roads should be constructed of broken stone (see Roads). In 1815, having been appointed surveyor-general of the Bristol roads, he was able to put his theories into practice. In 1819 he published a Practical Essay on the Scientific Repair and Preservation of Roads, followed, in 1820, by the Present State of Road-making. As the result of a parliamentary inquiry in 1823 into the whole question of road-making, his views were adopted by the public authorities, and in 1827 he was appointed general surveyor of roads. In pursuing his investigations he had travelled over thirty thousand miles of road and expended over £5000. Parliament recouped him for his expenses and gave him a handsome gratuity, but he declined a proffered knighthood. He died at Moffat, Dumfriesshire, on the 26th of November 1836.