M. Arago's Biographical Memoir of James Wall. 255 



ness of purpose, which, in the long run, defeat the most wily 

 intrigues, are seldom united with an inventive genius. Watt, 

 were it necessary, might be quoted as a convincing proof of 

 the fact. His grand invention and most felicitous conception, 

 that steam might be condensed in a vessel quite separated 

 fi'om the cylinder in which the mechanical action is going for- 

 ward, was completed in the year 1765 ; and in two years, scarcely 

 any progress was made to try its applicability upon the great 

 scale. At length, however, his friends put him in communica- 

 tion with Dr Roebuck, the founder of the great establishment 

 at CaiTon, so celebrated even at the present time. The en- 

 gineer and the projector now associated themselves together, 

 Watt yielding to him two-thirds of his patent. A machine 

 was speedily constructed upon the new principles ; it confirmed 

 all the anticipations of theory ; its success was complete, al- 

 though, in the mean time, Dr Roebuck's fortune was injured. 

 The invention of Watt would, without doubt, have repaired it ; 

 all that was required, was to apply to money lenders ; but our 

 brother associate thought it more simple to renounce his dis- 

 covery, and to change his career. In the year 1767, when Mr 

 Smeaton was executing the surveys and levellings between the 

 rivers Forth and Clyde, preparatory to those gigantic works 

 which were about to be executed in this part of Scotland, we 

 find Watt conducting analogous operations along a rival line. 

 Still later, he furnished a plan for the Monkland Canal, and ex- 

 ecuted it. Many projects of a similar kind, continued to occupy 

 the attention of our associate till the close of the year 1773. 

 Among these, we may mention the Crinan Canal, which was 

 subsequently formed by Mr Rennie ; also improvements in the 

 harbours of Ayr, Port-Glasgow, and Greenock ;* the building 

 of bridges at Hamilton and Rutherglen ; and the surveying the 

 district of the celebrated Caledonian Canal, upon which he made 

 a report, with plans and sections, subsequently referred to by 

 Mr Telford. Without depreciating the importance of these 

 labours I may still be permitted to add, that their interest 



* "We may also mention the deepening tlie river Clyde ; the improving 

 the navigation of the Forth and Devon, and the Water of Leven; the mak- 

 ing a canal from MacUrihanish Bay to Campbeltown, and another be- 

 tween the graad canal and the harbour of Borrowstownness. — Edit. 



