High Quality Content by WIKIPEDIA articles! The spinning mule is a machine used to spin cotton and other fibres in the mills of Lancashire and elsewhere. They were used extensively from the late eighteenth to the early twentieth century. Mules were worked in pairs by a minder, with the help of two boys: the little piecer and the big or side piecer. The carriage carried up to 1320 spindles and could be 150 feet (46 m) long, and would move forward and back a distance of 5 feet (1.5 m) four times a minute.. It was invented between 1775 and 1779 by Samuel Crompton. The self-acting (automatic) mule was patented by Richard Roberts in 1825. At its peak there were 50,000,000 mule spindles in Lancashire alone. Modern versions are still in production and are used to spin woollen and alpaca.