Hunt — On the Action of Waves on 8ea-heaches, 8fc. 263 



(1). A flow of water from the margin of repose to meet the ad- 

 vancing wave- crest. 



(2) . A return of the water to the margin of repose. 

 (3). A flow up the beach above the level of repose. 

 (4). A return to the said level from the point of furthest reach. 

 Numbers (1) and (2) seem to be the equivalents of the ordinary 

 primary and secondary wave-currents, whilst (3) and (4) seem to 

 represent the amount of wave force that has not been expended in 

 the plunge on the bottom. 



So far as their action on the beach is concerned, numbers (2) 

 and (3) combined may be regarded as forming one current from 

 the plunging point to that of furthest reach ; and numbers (1) and 

 (4) as forming one current from the point of furthest reach to that 

 of plunging. 



The flow of water down a beach is occasionally spoken of as 

 though it were the recoil of a wave that had previously broken on 

 the shore, whereas the united downward current must be referred to 

 two waves, the lower portion to the approaching wave, the upper 

 portion to the one that has preceded it. 



I shall endeavour to show that in their action on beach- 

 material these combined forward and backward currents are nicely 

 balanced. 



I shall approach this part of my subject by a description of 

 some observations made on the beach at Oddicombe, in Babbicombe 

 Bay, South Devon. 



This beach is well suited for observations on the action of 

 waves free from tidal complications, as, owing to its position in a 

 sheltered inlet in the north-western shores of Lyme Bay, it is 

 protected from all strong tidal currents. It is exposed to heavy 

 seas from only one quarter, viz. between E.S.E. \ E., and S.S.E. | E. 

 When the wind blows from any other direction, it is either oif-shore, 

 or blows off the land between Oddicombe and Portland, with a 

 maximum drift of about 40 miles. In the case of an E. S. E. wind 

 the drift is about 191 nautical miles. The general trend of the 

 beach is about N.N.E. and S. S.W. 



The following table will indicate the winds to which one part or 

 another is exposed, with their corresponding drifts, in nautical miles. 

 It will be seen that the E. S. E. wind, with the long drift of 191 

 miles, blows dead on shore. The winds blowing from any point 



