Lewis Paul had invented a machine for carding in 1748. Richard Arkwright made improvements to this machine and in 1775 took out a patent for a new carding engine, which converted raw cotton buds into a continuous skein of cotton fibres which could then be spun into yarn. Arkwright and John Smalley set up a small horse-driven factory at Nottingham. Needing more capital to expand, Arkwright partnered with Jedediah Strutt and Samuel Need, wealthy hosiery manufacturers, who were nonconformists. In 1771, the partners built the world's first water-powered mill at Cromford, employing 200 people mainly women and children. Arkwright spent £12,000 perfecting his machine, which contained the "crank and comb" for removing the cotton web from carding engines. He had mechanised all the preparatory and spinning processes, and he began to set up water-powered cotton mills as far away as Scotland. His success encouraged many others to copy him, so he had great difficulty in enforcing the patent he was granted in 1775. His spinning frame was a significant technical advance over the spinning jenny of James Hargreaves, in that very little training was required of his operatives, and it produced a strong yarn suitable for the warp of the cloth. Samuel Crompton was later to combine the two to form the spinning mule.