8 THE LAW OF DEPOSIT VI. 



press in towards the shore. When running round sharply-turning headlands, they 

 may be deflected for a moment ; but the inward pressure from the sea soon carries 

 them back to the coast. In like manner, the ebb tide falls off from the shore. 



This inward tendency of the flood tide carries all floating objects, or matter held 

 in suspension, either into the harbors, bays, and other recesses of the coast, or upon 

 the outer searcoast, where it comes under the influence of the wave action. In the 

 first case, the water comes to a state of repose in the interior of the bay, which is 

 very favorable to deposit. But it is the second case which we are to consider, and 

 with regard to which this general statement is correct. It is, if I may so say, the 

 prevailing law or result. 



Now, having brought the suspended matter within the reach of the wave action, 

 we are to investigate the nature of that action, by means of which this matter is cast 

 upon the shore, and forced to remain there. To ascertain this, I have had recourse 

 to the experiments of John Scott Kussell, Esq., detailed in his Report on Waves, in 

 the proceedings of the British Association for 1844. 



In order to discover the motion of water particles during wave transmission, 

 Mr. Russell made an experiment, or series of experiments, which exactly resemble 

 the case we are considering. He studied the motion of small particles visible in 

 the water, of the same or nearly the same specific gravity as water; and of small 

 globules of wax connected by very slender stems, so as to float at required depths. 

 (P. 340.) " The motions of these were observed from above on a minutely divided 

 surface on the bottom of the channel, and from the side through glass windows, 

 themselves accurately graduated, the side of the channel opposite to the window 

 being covered with lines precisely equal to those on the window, and similarly 

 situated." He calls the visible motion of the wave form, along the surface, the 

 motion of transmission, the actual motion of the particles themselves, the motion of 

 traTislation} 



The wave form is caused by the successive displacement of given masses of water, 

 by a mass preceding them, which has been set in motion by some active force. The 

 moving mass presses upon that before it dislodges it, and occupies its place. " The 

 water particles crowd upon one another in the act of going out of their old places into 

 the new; the crowd forms a temporary heap, visible upon the surface of the fluid ; and, 

 as each successive mass is displacing its successor, there is always one such heap, 

 and this heap travels apparently along the channel at that point where the process 

 of displacement is going on; and, although there may be only one crowd, yet it 

 consists successively of always another and another set of migrating particles. The 

 visible moving heap of crowding particles is the true wave." (P. 314.) 



" Let us select from the crowd of water particles an individual particle, and watch 

 its behavior during its migration. The progressive agitation first reaches it while 

 in a state of perfect repose ; the crowd behind it pushes it forward, and new par- 

 ticles take its place. One particle is urged forward on that before it, and being 

 still urged on from behind, by the crowd still swelling and increasing, it is raised 



* An apparatus similar to that described by Mr. Russell has been constructed for the purpose of 

 repeating his experiments on waves of the first order. 



