John McAdam was a Scottish engineer who was largely responsible for transforming road building into a science. As a youth, McAdam worked for an uncle in New York and managed to amass a considerable fortune. He returned to Scotland in 1783, and pursued other interests, including the development of a durable road surface. He held the position of turnpike trustee in several municipalities in Scotland and England. His process involved laying a base of large stones and topping them with crushed stone and gravel. The built-up road bed allowed drainage and a slightly convex surface helped to assure runoff. No bonding agent was used; the materials were forced into place by a large weighted roller at the time of construction, and later kept in place by the weight of road traffic. Most new roads in Europe in the mid-19th century were constructed in this manner, as well as many in the United States. The term "macadam" came to be applied to a variety of other road surfaces in later years.