MR. PALMER ON THE MOTIONS OF SHINGLE BEACHES. 575 



By extending the walls a sufficient distance into the sea, it was expected that a 

 commodious harbour would be formed, and the shingles diverted so far into deep 

 water, that they could not again appear above the surface until they were removed 

 beyond the harbour's mouth. 



The accumulation, however, immediately commenced, and continued as the work 

 advanced until it became apparent that no other effect was produced upon it than a 

 comparatively slight change of direction. The entrance of the harbour being much 

 encumbered with shingle, an additional pier or jetty was erected, and extended 

 about two hundred feet further into the sea without having approached the effect 

 intended. It is true that some advantage was derived from the extended pier, by in- 

 creasing the distance between the most violent action of the breakers and the still 

 water of the harbour. The shingles, therefore, pass the mouth in a more dispersed 

 form than they originally did, and hence they do not so readily form a barrier, neither 

 does its perpendicular height become so great. 



Much valuable information on this part of the subject is recorded in Lyon's History 

 of Dover, which, as it may at any time be consulted, is not repeated here. I shall 

 only remark, that from the succession of experiments made at that place, the general 

 result has been in a considerable acquisition of new land, which, although valuable 

 in itself, is not the object intended to be obtained. 



If, then, it be admitted that projecting piers will not prevent the encumbrance about 

 the mouth of a harbour, situated as those referred to in the tract of the restless beach, 

 it remains to be seen how far such works may be otherwise injurious. 



While the accumulative action is going on, every abrupt projection from the coast 

 is an impediment to the progressive motion of the beach until its angle is filled up. 

 Such abrupt projections offer no protection against the destructive action ; when, 

 therefore, by the increase of wind, the action of the sea becomes violent, an accumu- 

 lation previously caused by a projecting pier is rapidly removed, and again is rapidly 

 deposited where it is not resisted. And there is perhaps no combination of circum- 

 stances less capable of resisting, or more favourable to the deposition of, the shingle, 

 than is found in artificial harbours, shielded by an abrupt weather pier in a line of 

 beach. 



With a long continuance of violent winds from the same quarter, every accumu- 

 lation of loose shingle is broken down, and is hurried forward, while it unremittingly 

 appears to seek protection. During the recent gales every inlet within the tract of 

 the beach was seriously encumbered with it ; commenced with the heap accumu- 

 lated by the very pier that was intended to prevent such an effect (where such ex- 

 isted), and increased by the successive arrivals of those more remote, together with 

 that quantity commonly passing along the sloping plane, but now brought down by 

 the destructive action and forced along with accelerated motion. 



The ordinary state of the beach at Folkestone harbour is represented in Plate XXVII. 



4 E 2 



