Hunt — 0)i. the Action of Waves on Sea-beaches, 8fc. 259 



Having endeavoured to show that there is no evidence that a 

 wave of oscillation is transformed into a wave of translation on near- 

 ing the shore (although it gives rise to two distinct currents of trans- 

 lation in opposite directions), I will proceed to discuss the action of 

 these currents : firstly, on objects floating on the surface ; secondly, 

 on movable objects resting on the bottom. It seems clear that, if 

 these currents are equal and opposite, an object under their influ- 

 ence will travel with the one that is applied to the best advantage. 



In the case of floating objects, the application of the two wave- 

 currents is influenced by the form that the wave assumes on entering 

 shallow water. The steep anterior wave-slope acts diversely on 

 different objects according to their form and weight. 



This fact was brought to my notice by accident. Whilst 

 watching some waves running over a shelving bottom in my tank 

 I observed that a chip of wood dropped into the water at a certain 

 point would recede from the shore, that the cork of a phial dropped 

 in in the same place would go towards the shore, but that a small 

 piece of water-soaked wood would go from the shore with the chip. 

 On this occasion there was a slight surface cm-rent from the shore 

 outward, which explained the motion of the light chip ; but this 

 current did not account for the cork going one way, and the water- 

 soaked wood the other. The explanation is as follows : — The out- 

 ward current, which carried the light chip over the steep slopes of 

 the advancing waves, was unequal to the task of carrying the cork 

 outwards so fast as the latter slid down the wave-slopes shorewards. 

 The cork, by hanging on the anterior wave-slopes, was under the 

 influence of the forward wave- current in each wave longer than 

 under that of the backward, and thus by the mere accident of weight 

 travelled in a contrary direction to that of the chip. The water- 

 soaked piece of wood, though heavier than either chip or cork, did 

 not attempt to surmount the waves. Its specific gravity approxi- 

 mating to that of water, it had little buoyancy, and the waves ac- 

 cordingly broke over it. Thus, whilst exposed to the full force of 

 the backward wave-currents, it partially evaded the forward currents, 

 and in consequence travelled away from the shore, under the 

 influence of the said backward currents. On another occasion I 

 found that when the waves acted on a deep narrow toy-boat sunk 

 to the water's edge, end on, the boat travelled with them ; but that 



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