172 



KENNIE'S BRIDGES. 



PART VII. 



enabling it better to resist the lateral thrust. Dr. Ro- 

 bison had much discussion with Mr. Rennie on these 

 and many other points, and the information he obtained 

 was shortly after worked up into numerous original con- 

 tributions of great value ; amongst which may be men- 

 tioned his articles in the ' Encyclopedia ' on the Arch, 

 Carpentry, Roof, Waterworks, Resistance of Fluids, and 

 Running of Rivers l on all of which subjects Mr. 

 Rennie had much original information to impart. It 

 may readily be imagined that the evenings devoted by 

 Dr. Robison to conversation and discussion on such 

 topics at Rennie' s house were of interest and advantage 

 to both ; and when the Doctor returned to his Edinburgh 

 labours, he carried with him the cordial affection and 

 respect of the engineer, who continued to keep up a 

 correspondence with him until the close of his life. 



In the early part of his career Mr. Rennie was called 

 upon to furnish designs of many bridges, principally in 

 Scotland, which, however, were not carried out, in most 

 cases because the requisite funds could not be raised to 

 build them. Thus, in 1798, he designed one of eight 

 cast iron arches to span the river Don at Aberdeen. 

 Four years later he was called upon to furnish further 

 designs, when he supplied three several plans, two of 

 granite bridges ; but the structures were of too costly a 

 character for the people of Aberdeen then to carry out. 

 The first important bridge which Mr. Rennie was autho- 

 rised to execute was that across the Tweed at Kelso, and 

 it afforded a very favourable specimen of his skill as an 

 architect. It was designed in 1799 and opened in 1803. 

 It consists of five semi-elliptical arches of 72 feet span, 

 each rising 28 feet, and four piers each 12 feet thick, 



1 Dr. Robison was the first contri- 

 butor to the ' Encyclopedia ' who was 

 really a man of science, and whose 

 articles were above the rank of mere 

 compilations. He sought information 

 from all quarters searched the works 



of foreign writers, and consulted men 

 of practical eminence, such as Rennie, 

 to whom he could obtain access, and 

 extraordinary value was thus im- 

 parted to his articles. 



