COMMENCEMENT OF WORKS. 



35 



of the dam, other temporary works, such as timber viaducts, etc., 

 were constructed. 



By means of these timber viaducts, which carried the rail- 

 ways over and through the mud until firm ground was reached, 

 access to large areas otherwise inaccessible was obtained, and 

 the general excavations proceeded with. 



The foundations within the shallow were excavated partly 

 in open cutting and partly in timbered trenches, and all between 

 the outer and inner dams within timbered trenches. 



Southampton Tidal Dock. 1 The site of this dock (Fig. 15), 

 being on the foreshore, was entirely covered at every tide, the 

 average level of the mud being 11 feet below high water of 

 springs. 



To reclaim it, an embankment, 3000 feet in length and not 

 less than 20 feet wide at the top, was therefore formed to enclose 

 the whole area amounting to 42 acres of mud land. 



The material used for this purpose consisted chiefly of chalk 

 and a little gravel tipped into a trench previously excavated 

 in the mud by grabs working from a barge. The trench varied 

 from 5 to 20 feet in depth below the mud surface, and from 20 

 to 25 feet wide. 



The work was puddled with mud excavated from the sites 

 of the work run out upon the embankment in trucks, where 

 it was cast out and assumed its natural slopes, which was 

 occasionally as much as 1 in 40. This formed an efficient 

 Cuddle, and made the bank thoroughly water-tight. After 

 completion, the bank withstood unusually powerful gales and 

 high seas without sustaining damage. 



1 Engineering, vol. 1. p. 308. 



