CHAP. VII. GHIMSBY DOCK WALLS. 207 



At the opposite end of the island he was consulted (in 

 1796) as to the best method of improving the harbour 

 of Torbay, and submitted a series of able plans, only a 

 small part of which were carried into effect. Shortly 

 after (in 1797) we find him inspecting the sluicing 

 arrangements of the harbour then under construction at 

 Grimsby, when he furnished a plan of the great lock 

 which it was necessary to place at the entrance of the 

 canal leading to the dock, and which was in his opinion 

 indispensable for scouring the harbour entrance and 

 keeping it clear of silt. This lock was executed according 

 to his plans by the local engineer ; but it appeared that 

 sufficient precautions had not been taken in founding and 

 proportioning the dimensions of the retaining walls, on 

 which Mr. Rennie had not been requested to give an 

 opinion, the work appearing to be of so simple and 

 ordinary a character. But shortly after the building 

 was begun, a considerable portion gave way, and he 

 was again sent for to inquire and report as to the cause 

 of the failure. He found that the defect lay in the 

 nature of the ground on which the foundation was built, 

 which was so soft that it would not bear the weight of 

 solid walls of the ordinary construction. Always ready 

 with an expedient to meet a difficulty, he directed that, 

 without diminishing the quantity of material employed, 

 it should be distributed over a greater base, for the 

 purpose of securing a larger bearing surface. With 

 this object he prepared his plan of the requisite 

 structure, adopting the expedient of hollow walls, which 

 he afterwards employed so extensively in his pier and 

 harbour works. They not only bore upon a larger base, 



ample accommodation, at an esti- 

 mated capital cost (at the time the 

 plans were made) of only 130,000?. 

 What would not Glasgow give now 

 to have the benefit of Rennie's docks ? 

 Indeed it is remarkable that, to this 

 <lay, so little has been done to realize 



his idea, and provide dock accommo- 

 dation for the trade of the Clyde, 

 which is now quite as much needed 

 as the same kind of accommodation 

 was in the Thames at the beginning 

 of the present century. 



