JOHN LOUDON, the introducer of macadamized road-making, was descended from an old and respectable family in Kirkcudbrightshire, and was born in Ayrshire, Scotland, in 1756. His plan of road improvement occurred to him when acting as trustee for a district of roads in Ayrshire, and was first carried into practice on the Bristol roads, of which he had been appointed surveyor-general in 1815. He explained his system fully in two works,—A Practical Essay on the Scientific Repair and Preservation of Public Roads, London, 1819; and Remarks on the Present State of Road-making, London, 1820. In 1827 he was appointed general surveyor of roads; and for the large sums which he expended while performing the duties of this office, he was afterwards compensated by two grants from government, amounting together to £10,000. The honour of knighthood, which he declined, was conferred upon his son in 1834. Macadam died in 1836.