The second volume starts with Watt?s move from Glasgow to Birmingham where he finally succeeded in perfecting his steam pumping machine at the Matthew Boulton?s Soho Manufactory. The potential for this engine caused Boulton to persuade Watt in 1775 to ask Parliament to extend his 1769 patent which was granted to 1800. This led to the formation of the famous partnership of Boulton and Watt. Watt?s engine quickly replaced earlier Newcomen engines in the Cornish copper mines with seemingly rich prospects. But the patent premiums charged soon roused the hostility of the mine owners so that rival engineers such as Jonathan Hornblower developed alternative types of engines, leading to disputes over the validity of Watt?s patent. Watt?s second marriage to Ann McGregor and the hopes and tribulations of his growing family are covered. His interest in chemistry is not neglected for this is the period when he developed his successful letter copying machine. He was elected to the Royal Society of London in 1785 for his essay on the composition of water and this was the year when he, at last, paid off all of his outstanding debts, so could look forward, hopefully, to a prosperous future.