In 1764, James Hargreaves is credited as inventor of the spinning jenny which multiplied the spun thread production capacity of a single worker — initially eightfold and subsequently much further. Others credit the invention to Thomas Highs. Industrial unrest and a failure to patent the invention until 1770 forced Hargreaves from Blackburn, but his lack of protection of the idea allowed the concept to be exploited by others. As a result, there were over 20,000 spinning jennies in use by the time of his death. Also in 1764, Thorp Mill, the first water-powered cotton mill in the world was constructed at Royton, Lancashire, and was used for carding cotton. With the spinning and weaving process now mechanized, cotton mills cropped up all over the North West of England.