CHAP. VII. PRINCIPLES OF HARBOUR CONSTRUCTION. 



217 



of Forth, in the year 1807, he very clearly laid down 

 the Lroad principles on which he held that such works 

 should be designed : " Every harbour," he said, " should 

 be so constructed as to have its mouth as much ex- 

 posed as possible to the direction from whence vessels 

 can most conveniently enter in stormy weather when 

 they are least manageable ; but the Heads should be 

 made of such a form as to admit of the least sea entering 

 it, or so as to occasion as little swell within the haven as 

 possible. This cannot by any practicable construction 

 be entirely avoided ; but means should be provided within 

 the harbour so as to reduce the recoil of the waves to a 

 minimum, for it is the undertow or retiring sea, after 

 the breaking of a wave, that renders vessels most un- 

 manageable by making the helm lose its effect. At such 

 a time the mariner is at a loss what to do, or how to 

 manage his vessel ; and for the want of due attention to 

 these particulars many of the most considerable artificial 

 harbours in the kingdom are exceedingly difficult of 

 access, and some of them are most unsafe even when 

 entered." The great point, he held, was not only to 

 make a harbour to keep out the sea, but to do so in 

 such a manner as not to render its entrance from the 

 most exposed or dangerous quarter difficult in stormy 

 weather, when its shelter was most needed ; and while it 

 must be so designed as to afford a safe shelter for ship- 

 ping, it must also be easy to enter and easy to get 

 out of. 1 That so many modern harbours, constructed 



1 From the following brief descrip- 

 tion it will be observed how skilfully 

 he carried out these views in laying 

 out the intended harbour at Charles- 

 ton. He proposed to construct two 

 great piers, one placed at the western 

 extremity of the little inlet, to which 

 :i railway was being laid down the 

 straight part extending outwards about 

 154 yards, from which there were to 

 be two kants of about 64 yards each, 

 the last going 57 yards below low- 



water mark. From thence there was 

 to be a return bend about 70 yards 

 long, in a direction considerably to the 

 north of east. At 50 yards from the 

 extremity of this pier, another of the 

 same length was proposed to be made, 

 forming an angle with it of about 120 

 degrees, with two other kants similar 

 to the former, and a larger one ex- 

 tending to the shore ; the entrance 

 being 50 yards wide, and the outer 

 arm or kant of the east pier making 



