of Edinburgh, Session 1882-83. 
67 
have on the mighty energy of an all hut irresistible ocean wave ? 
They indeed seem to have hut little relation to each other. Before 
coming to any conclusion on this point it will he necessary for us 
narrowly to examine what really is the effect of oil on already formed 
waves. 
Let us therefore examine any small sheet of water over which 
there is passing a series of well-formed waves, and see if the explana- 
tion we have given of the formation of small waves or ripples applies 
here to the effect of oil. As we look upon the waves as they pass us, 
we observe that their surface is very far from being smooth ; on the 
contrary, a regular series of waves are being formed by the wind on 
the surface of the large ones. These waves are small at the bottom 
of the large waves, and grow in size as they approach the top. In 
fact, the wind is repeating on the waves very much the same process 
as when it first begins to blow on calm water. This action on the 
large waves is, however, infinitely more rapid than on the calm water, 
as the wind is blowing with far greater violence than ever it does on 
calm waters ; and further, the slope of the surface of the water on 
large waves being towards the wind, causes its action to be much 
more powerful than on a horizontal surface. Now, the breaking of 
large waves is very evidently connected with the formation of these 
smaller ones which form on them, and grow in strength towards their 
tops, where they form crests and break, thereby adding dangerous 
qualities to the wave. 
We have already seen that oil prevents the formation of small 
waves on calm water ; it will therefore prevent the formation of 
small waves on the surface of large ones, and will thereby prevent 
the formation and breaking of their crests. In order to test whether 
this conclusion is correct or not, let us again examine the surface 
of the small sheet of wind-driven water, and, while watching the 
waves as they glide past, let us pour over them a little oil. At once 
a change takes place j small waves no longer form on the already 
made waves, the latter simply continue on their course smoothed 
and rounded on their surface. We see that the oil by precluding 
the formation of small waves, has prevented the roughness and the 
pointed crests which previously formed on the waves and which 
break when the wind is sufficiently violent. Further, it seems 
probable that the smoothness of the large waves, produced by the 
