Subject to Law 



sun comes from an immense distance, it follows 

 that it has much less effect than the small attrac- 

 tion of the moon, which comes from very near 

 at hand. 



Her influence over our earth is exerted far 

 more strongly with respect to those ocean-waters 

 lying just under herself, and far less with respect 

 to those waters on the farther side of the globe. 

 The effect of these different pullings is to raise a 

 double wave or swell, — one on the surface of 

 the ocean just below the moon, and one on the 

 opposite side of the earth. The waves mean 

 high tides ; and low tides occur at places half- 

 way between them. 



Were the whole Earth covered by one con- 

 tinuous sheet of water, these tidal waves would 

 travel round and round the globe, in a fashion 

 easy and pleasant for students of the subject. 

 Unfortunately for the said students, their motions 

 are very complicated. In the northern hemi- 

 sphere, where land is abundant, the tidal waves 

 are greatly interfered with by continents and 

 islands. Often the most that each can do, as 

 it sweeps along, is to send side-waves and 

 currents journeying northward into channels and 

 bays, estuaries and lesser seas. 



Through the open ocean the tidal wave has no 

 D 33 



