b. 21 September 1756 Ayr, Ayrshire, Scotland
d. 26 November 1836 Moffat, Dumfriesshire, Scotland
McAdam was the son of one of the founder of the first bank in Ayr. As an infant, he nearly died in a fire which destroyed the family's house of Laywyne, in Carsphairn parish; the family then moved to Blairquhan, near Straiton. Thence he went to the parish school in Maybole, where he is said to have made a model section of a local road. In 1770, when his father died, he was sent to America where he was brought up by an uncle who was a merchant in New York. He stayed in America until the close of the revolution, becoming an agent for the sale of prizes and managing to amass a considerable fortune. He returned to Scotland where he settled at Sauchrie in Ayrshire. There he was a magistrate, Deputy-Lieutenant of the county and a road trustee, spending thirteen years there. In 1798 he moved to Falmouth in Devon, England, on his appointment as agent for revictualling of the Royal Navy in western ports.
He continued the series of experiments started in Ayrshire on the construction of roads. From these he concluded that a road should be built on a raised foundation with drains formed on either side, and should be composed of a number of layers of hard stone broken into angular fragments of roughly cubical shape; the bottom layer would be larger rocks, with layers of progressively smaller rocks above, all bound together with fine gravel. This would become compacted and almost impermeable to water by the action of the traffic passing over it. In 1815 he was appointed Surveyor-General of Bristol's roads and put his theories to the test.
In 1823 a Committee of the House of Commons was appointed to consider the use of 'macadamized' roads in larger towns; McAdam gave evidence to this committee, and it voted to give him £10,000 for his past work. In 1827 he was appointed Surveyor-General of Roads and moved to Hoddesdon, Hertfordshire. From there he made yearly visits to Scotland and it was while returning from one of these that he died, at Moffat in the Scottish Borders. He had married twice, both times to American women; his first wife was the mother of all seven of his children.
McAdam's method of road construction was much cheaper than that of Thomas Telford, and did much to ease travel and communications; it was therefore adopted by the majority of Turnpike Trusts in Britain, and the macadamization process quickly spread to other countries.
b. December 1856 Hutchesontown, Glasgow, Scotland
d. 16 March 1920 Pollokshields, Glasgow, Scotland
MacArthur served his apprenticeship in the laboratory ofTennant's Tharsis Sulphur and Copper Company in Glasgow. In 1886 he was appointed Technical Manager of the Tennant-run Cassel Gold Extracting Company. By 1888 he was advocating a treatment scheme in which gold was dissolved from crushed rock by a dilute solution of alkali cyanide and then precipitated onto finely divided zinc. During the next few years, with several assistants, he was extremely active in promoting the new gold-extraction