I 8 Divellers of the Sea and Shore 



on the earth and Its oceans than has the moon. What 

 is It, then, that gives the latter its apparent precedence 

 over the sun in the regulation of the tides? 



To conceive this clearly, we must take into account 

 the relative distances of these two bodies from the 

 earth. Our globe is about eight thousand miles in 

 diameter. Yet this is a very small fraction of the dis- 

 tance to the sun which, roughly speaking, is ninety- 

 three million miles away. Consequently the pull on the 

 earth is about the same throughout its entire mass; or, 

 to put it another way, the attraction for that side of the 

 earth nearest the sun is but slightly more than for the 

 side more remote. A quite different aspect presents 

 itself, however, when we consider the moon. The dis- 

 tance of our satellite from the earth being only a quar- 

 ter of a million miles, it will be seen that the diameter 

 of the earth at once becomes a very considerable frac- 

 tion. The result is that the side of the earth facing the 

 moon is subjected to a much stronger pull than the op- 

 posite side. Now the waters of the ocean respond 

 more readily to the attraction of the moon than does 

 the hard crust of the earth, and as a consequence they 

 are caused to bulge out on that side nearest the moon. 

 Again, since the attractive force of the moon is weakest 

 of all at the opposite side, and since the waters on that 

 side are attracted less than the solid earth — the latter 

 being pulled away, so to speak — they bulge outward on 

 the side away from the moon also. 



From this it will be seen that we get a condition 

 wherein two high tides are produced simultaneously 

 on opposite sides of the earth. It must be borne in 

 mind, however, that the earth is continually turning on 



