John Metcalf (1717-1810), English road builder, also known as Blind Jack of Knaresborough. Although blinded at 6 by an attack of smallpox, he planned the construction of 5 kilometres of road. Having successfully completed this turnpike road (toll-paying) in 1765. He spent the next 30 years building a total of 290 kilometres, for which he was paid ?65,000. Metcalf always performed a survey of the route on his own, regardless of the terrain. He adapted the viameter, which measured distances, so that he could read it by touch. His roads were even constructed across marshy areas, using a base of vegetation.