160 IRE LIFE OF TILE FLKLD&, 



MIND UNDER WATER. 



THE thud, thud of a horse's hoof does not alarm fish. 

 Basking in the sun under the bank, a jack or pike 

 lying close to the surface of the water will remain 

 unmoved, however heavy the sound may be. The 

 vibrations reach the fish in several ways. There is 

 what we should ourselves call the noise as conveyed 

 by the air, and which in the case of a jack actually 

 at the surface may be supposed to reach him direct. 

 Next there is the vibration passing through the water, 

 which is usually pronounced to be a good medium. 

 Lastly, there is the bodily movement of the substance 

 of the water. When the bank is hard and dry this 

 latter amounts only to a slight shaking, but it 

 frequently happens that the side of a brook or pond 

 is soft, and "gives" under a heavy weight. Some- 

 times the edge is even pushed into the water, and the 

 brook in a manner squeezed. You can see this when 

 cattle walk by the margin ; the grassy edge is pushed 

 out, and in a minute way they may be said to con- 

 tract the stream. It is in too small a degree to have 

 the least apparent effect upon the water, but it is 

 different with the sense of hearing, which is so delicate 

 that the bodily movement thus caused may be reason- 



