Friends of Boulton and Watt--The Lunar Society--Provincial scientific societies--Distinguished associates of the Lunar Society--Dr. Darwin--Dr. Priestley, his gifts and accomplishments--Josiah Wedgwood--Meetings and discussions of the Lunar Society--Dr. Priestley’s speculations and experiments--Composition of water, Watt and Cavendish--Bleaching by chlorine--Sun-pictures--Saint-Fond at Birmingham, his descriptions of Watt and Priestley--Decline of the Lunar Society 367–385 CHAPTER XIX. Increasing debasement of the coinage--Punishments for counterfeiting--Birmingham coiners--Boulton refuses orders for base money--Executes a contract for coin for the East India Company--Applies the steam-engine to coining--Improves the coining apparatus--Political action in relation to base coin--Strikes model coins for inspection of the Privy Council--Opposed by the Mint authorities--Presents model coins to the king--Executes coinage orders for foreign governments--His success--Medalling--Description of the Soho mint--Large consumption of copper in coining--Threatened attack on Soho by a mob--Boulton executes the new copper coinage for Great Britain--Erects the new Government Mint on Tower Hill, and mints for foreign countries--Watt’s estimate of Boulton’s improvements in coining 386–399 CHAPTER XX. Prosperity of Soho--Relaxed strain upon Boulton and Watt--Watt’s pleasure tours--His interview with the king at Windsor--Matthew Robinson Boulton, and James Watt, jun., join their fathers in the business--Their character and attainments--Boulton and young Watt--Young Boulton’s return from Paris--The French revolution--The Birmingham riots--Priestley’s house destroyed--Unpopularity of the “Philosophers”--Young Watt and the Jacobins--Watt’s flight from Paris--Denounced by Burke--Mr. Watt’s fear for his son’s safety--The sons join their fathers in partnership--Important services of the young partners--Evasion of engine-dues, resistance of the Cornish mining companies--Legal proceedings and favourable judgments--Progress of the engine business--William Murdock--His valuable services--His engine improvements--Return to Soho--Invents gas-lighting--Winsor’s wonderful schemes--Murdock’s various inventions--Substitute for isinglass, his idea of power wasted in streets, atmospheric railway, &c.--His death 400–433 CHAPTER XXI.