28 



HARBOUR CONSTRUCTION. 



the position of the bank being indicated for hours, or even days 

 together, by a patch of white foam. The general depth of water 

 upon this bank at low water is 10 fathoms, only one isolated 

 point rising to within 6 fathoms of the surface. 



TABLE 1. LENGTH OP WAVE EQUAL TO DEPTH OF WATEB. 



TABLE 2. LENGTH OF WAVE TEN TIMES AS GREAT AS DEPTH OF WATEU. 



During strong gales waves break upon the south-west end 

 of the Dogger Bank, off the coast of Yorkshire, the depth of 

 water upon that part of the bank varying from 7 to 10 fathoms. 



As a further indication of the depth and extent to which 

 storm-waves are felt, Sir John Coode states that he found the 

 shingle of the Chesil Bank disturbed by wave action, during the 

 heaviest winter gales, at a depth of 8 fathoms, the shingle thus 

 disturbed being of large size. 1 



Captain Calver, R.N., observed that in gales of wind off the 



1 Minutes of Evidence, Select Committee on Harbours of Refuge, 1857. 



