264 



Scientific Proceedings, Royal Dublin Society. 



south of E.S.E. (if they impinge on the beach at all) will tend 

 to drive the shingle to the north, and vice versa. In every case 

 winds impinging on the beach from the southward have longer 

 drifts than those impinging on it from the northward : — 



In the course of the autumn of 1882 I made a series of obser- 

 vations at Oddicombe, roughly measuring the strand on each 

 occasion, and noting the change in the shingle-ridges. At the ex- 

 treme north-eastern end a cove is partially divided off from the 

 main beach by some large isolated rocks, and in this cove the strand 

 was always composed of shingle (chiefly limestone), extending from 

 low-water mark to the foot of the cliffs, which cliffs bound the 

 beach on the land side, and are only reached by the water in 

 exceptional gales. For the purpose of measuring the strand in 

 this cove, on the 14th October, 1882, I placed together three of 

 the largest beach-stones I could find, just above the reach of the 

 waves. The tide was low and on the turn, and the waves, during 

 the time the level of repose of the water was stationary, had ac- 

 cumulated a ridge, or bank, of small stones. On completing my 

 measurements, I found that with the rising tide the waves had 

 struck my three mark-stones, and that they were nov/ in line, one 

 behind another. Thinking it a good opportunity to observe the 

 action of waves on shingle of different sizes, I stood, watch in hand, 

 to record their action on these three mark-stones. In three minutes 

 the first stone (the one nearest the sea) had fallen down the slope 



