Driven 1697-98 from the east side of Mill Brook south of Speedwell Mill. The lower part of the sough collapsed in the 18th century and the flow of water came to the surface in a field to the east of Speedwell Mill forming a feature known as the Boiling Pot which persisted until the early 19th century, perhaps ended by the driving of Cromford Sough's south extension. The sough ended a short way beyond the climbing shaft situated about 300 yards south of the end of the metalled part of Summer Lane.