The spinning jenny is a multi-spool spinning wheel. It was invented circa 1764 by James Hargreaves in Stanhill, near Blackburn, in Lancashire in the north west of England. The device dramatically reduced the amount of work needed to produce yarn, with a single worker able to work eight or more spools at once.

James Hargreaves was born in Oswaldtwistle, near Blackburn, in 1720. He received no formal education and was never taught how to read or write. He moved to Stanhill looking for work and raised a family there, working as a spinner and carpenter.

Blackburn was known for the production of Blackburn greys, a type of fabric that combined linen warp and cotton weft. At the time cotton production could not keep up with demand, and Hargreaves spent some time considering how to improve the process. The most common story told about the invention of the device is that his daughter, Jenny, knocked over one of their own spinning wheels. The device kept working as normal, with the spindle now pointed upright. Hargreaves realized there was no particular reason the spindles had to be horizontal, as they always had been, and he could place them vertically in a row.

Whatever the inspiration, the basic idea was developed as a machine with eight spindles at one end, spun from a larger than normal wheel at the other. A set of eight rovings were attached to a beam that could roll from the spindle end to the wheel end on a horizontal frame, and the operator could roll it back and forth over the yarn to draw it out to the proper thickness. A clamp-like device in the roving beam allowed the operator to then release all the threads at once, to be collected on spools.

The flying shuttle had increased yarn demand by the weavers by doubling their productivity, and now the spinning jenny could supply that demand by increasing the spinner's productivity even more. The machines were often operated by children, who could more easily move about them. The machine produced coarse yarn that lacked strength, but it was still suitable for filling out the weft of fabric, using stronger yarn for the warp. Later developments improved the quality of the yarn, and increased the number of spindles to eighty or more.

Hargreaves kept the machine secret for some time, but produced a number for his own growing industry. The price of yarn fell, angering the large spinning community in Blackburn. Eventually they broke into his house and smashed his machines, forcing him to flee to Nottingham in 1767. There he set up shop producing jennies in secret for one Mr. Shipley, with the assistance of a joiner named James.

Eventually Hargreaves applied for a patent on the jenny in July 1770. By this time a number of spinners in Lancashire were already using copies of the machine, and Hargreaves sent notice that he was taking legal action against them. The manufacturers met, and offered Hargreaves £3000. He at first demanded £7000, and at last stood out for £4000, but the case eventually fell apart when it was learned he had already sold several in the past.

The partnership with Shipley carried on "with moderate success" Hargreaves' death on April 22nd, 1778. That year Samuel Crompton invented the spinning mule , combining the spinning jenny with Richard Arkwright's spinning frame and again dramatically increasing yarn production.

See also

• Timeline of clothing and textiles technology