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XXVII. Observations on the Motions of Shingle Beaches. By Henry R. Palmer, Esq. 



F.R.S. Civil Engineer. 



"C 



Received March 12, — Read April 10, 1834. 



The extraordinary prevalence of tempestuous weather during the last autumn 

 having occasioned numerous disasters on our coast, the public attention was directed 

 in an unusual degree to the imperfections of many of the harbours, and more parti- 

 cularly to those which are encumbered with accunmlations of shingle. The access to 

 harbours thus circumstanced is generally uncertain, and in tempestuous weather is 

 frequently dangerous, or even impossible. 



The action of the sea, which gives motion to the shingles and produces the evils 

 complained of, has long been a subject of speculation ; but I have not found that it 

 has been systematically investigated. Indeed, the contrariety of opinions advanced 

 upon the subject, sufficiently indicates an entire absence of that satisfactory mode of 

 inquiry which is essential to the foundation of a safe and practical deduction. 



Very little has been written upon the subject ; and such facts as have been men- 

 tioned have only been referred to incidentally, or with a view to geological science. 

 My present object is exclusively practical in its nature, and my observations have 

 been limited to such facts as would assist in establishing certain and fixed rules for 

 controuling the motions of the beach, so far as to enable us to preserve a clear channel 

 through it in all seasons, and in every variety of weather ; and to accumulate and pre- 

 serve the shingles, where it is needful to do so. 



The subject at first sight appears greatly complicated ; and were it necessary to 

 discuss minutely all the modifications arising from the variety of forms and local cir- 

 cumstances, it would perhaps be too much so for general description. I have, how- 

 ever, limited my investigation to those simple and unvarying laws to which nature 

 always adlieres ; and therefore the following observations must be considered as re- 

 stricted only to certain general principles, subject to a variety of modifications. 



The principles which I propose to illustrate will (under similar circumstances) at 

 all times exhibit the same phenomena, but for the sake of perspicuity I shall now 

 only refer to the coasts of Kent and Sussex. 



Section 1. 



That the pebbles which compose the shingle beaches on these coasts are kept in 

 continual motion by the action of the sea, and that their ultimate progress is in an 

 easterly direction, are facts long known and commonly observed. The following 



4 D 2 



