1 : 31680 This drawing covers part of Lincolnshire, showing drains across the fens highlighted in blue. These date from the 17th century, when James I appointed Dutch engineer Cornelius Vermuyden to direct the drainage of the wetlands. Many local people opposed the scheme as the plan involved commonland on which they grazed cattle. As a result of Vermuyden's work, the fens changed radically in appearance, from an area of flooded marshes to one of extensively farmed agricultural land. In the middle of the sheet is a series of decoy ponds, built in the 17th and 18th centuries to lure wildlife. Yeakell, Thomas Jr.