this being the first device of the modern era to significantly enhance productivity. But by September 1733 the Colchester weavers, were so concerned for their livelihoods that they petitioned the King to stop Kay's inventions. The flying shuttle was to create a particular imbalance by doubling weaving productivity without changing the rate at which thread could be spun, disrupting spinners and weavers alike. Kay tried to promote the fly-shuttle in Bury, but could not convince the woollen manufacturers that it was sufficiently robust; he spent the next two years improving the technology, until it had several advantages over the device specified in the 1733 patent. This was to be one of his difficulties in the coming patent disputes. In 1738 Kay went to Leeds, where his problem had become royalty collection (the annual licence fee was 15 Shillings per shuttle). He continued to invent, patenting some machines in the same year, though these were not taken up industrially. The Shuttle Club Kay (and, initially, his partners) launched numerous patent infringement lawsuits, but if any of these cases were successful, compensation was below the cost of prosecution. Rather than capitulate, the manufacturers formed "the Shuttle Club", a syndicate which paid the costs of any member brought to court; their strategy of patent piracy and mutual indemnification nearly bankrupted Kay. In 1745, he and Joseph Stell patented a machine for cloth ribbon weaving, which they anticipated might be worked by water wheel, but they were unable to advance their plans because of Kay's legal costs. Impoverished and harassed, Kay was compelled to leave Leeds, and he returned to Bury. Also in 1745, John's twelfth, and final, child, William, was born. Kay remained inventive; in 1746 he was working on an efficient method of salt production, and designing improvements to spinning technology: but that made him unpopular among Bury spinners. Also, fly-shuttle use was becoming widespread in weaving, increasing cotton yarn demand and its price; and Kay was blamed. Life in France He had suffered violent treatment in England, but he did not leave the country on that account, but because of his inability to enforce (or profit from) his patent rights. Trudaine's Bureau de Commerce was known to support textile innovations (and would later actively recruit immigrant inventors). Probably encouraged by the prospect of state support, in 1747, Kay left England for France (where he had never been before, and did not