First attempts to construct steamboats--All attempts fail until Watt’s condensing engine invented--The locomotive of Watt and Murdock--William Symington--His model locomotive--Symington at Edinburgh--Steam-engine for canal-boats proposed by Symington--Miller’s paddle-boats--Symington, Miller, and Taylor co-operate to produce a steamboat--Sir John Dalrymple’s inquiries of Boulton on the same subject--Boulton’s reply--Symington’s engine finished and fitted in Miller’s boat--Successful experiment--Symington makes another engine, further experiments--Miller applies to Boulton and Watt to join speculation--Watt’s reply--Symington’s engine for the ‘Charlotte Dundas’--Symington’s success frustrated--Fulton and Bell inspect the ‘Charlotte Dundas’--Fulton’s steamboat on the Seine--His ‘Nautilus’--His application to James Watt, jun.--Boulton’s caution, his letter to Lord Hawkesbury--Fulton orders an engine from Soho for the ‘Clermont’--Its success--Henry Bell’s steamboat ‘Comet’--Development of steam-navigation--First rendered practicable through Watt’s inventions 434–455 CHAPTER XXII. Watt withdraws from Soho--Boulton continues his interest in business--His patent for raising water--The burglary at Soho--Sir Walter Scott and Boulton--Watt in retirement--Search for investments--Purchases land--Makes a foreign tour--Death of Mrs. Keir--Painful bereavements--Death of Dr. Black--Deaths of members of the Lunar Society--Watt’s family bereavements--Watt’s studies on the inhalation of gas--Gregory Watt, his brilliant talents--His friendship with Humphry Davy--His excursions and tours--His scientific pursuits--His illness and death--Davy on Gregory’s death--Death of Professor Robison--Watt’s estimate of Robison--Boulton’s last days, his death and funeral--His character--Opinions of his contemporaries, Boswell and others, concerning him--Attachment of the workmen--His Mutual Assurance Society for the workmen--His powers of organisation--His business qualities--His strength, courage, and perseverance in fighting the battle of the steam-engine--Watt’s estimate of Boulton--Boulton’s generosity 456–487 CHAPTER XXIII.