plicated by the fact that the sun also has an 

 attraction for the earth as well as the moon. 

 But from the fact that the sun is something 

 like 400 times further from the earth than the 

 moon is, and also the fact that the attraction 

 of one body for another varies inversely as the 

 square of the distance, the moon has an im- 

 mense advantage over the sun, although so 

 much smaller. If the power of the moon were 

 entirely suspended, or if the moon were blotted 

 out of existence, there would still be a tide. 

 The fluctuation between high and low tide 

 would not be nearly so great as it is at pres- 

 ent, but it would occur at the same time each 

 day, because it would be wholly a product of 

 the sun. 



It will be easily seen that these two forces 

 acting upon the water at the same time will 

 cause a complicated condition in the move- 

 ment of the waters of the ocean. There will 

 come a time once in twenty-eight days when 

 tLe sun and the moon will act conjointly, and 

 both will pull in the same direction at the 

 same time upon the water. This joint action 

 of the sun and moon produces the highest tide, 

 which is called the " spring " tide. From this 

 point, however, the tides will grow less each 

 day, because the relation of the sun and moon 

 is constantly changing, owing to the fact that 

 it requires 365 days for the sun to complete 

 his apparent revolution around the earth, 



