110 SEASIDE DIVINITY. 



waves. The variety and number of causes and 

 effects thus to be taken into view, render the 

 theory of the tides one of the most complicated 

 subjects in natural science, and has called forth 

 the genius and taxed the powers of the ablest 

 investigators. All that can be done in a work of 

 this kind, is to present a general view of the 

 subject, as plain and lucid as possible without 

 mathematical calculations. 



That the ebbing and flowing of the tides depend 

 on solar and lunar influences there can be no 

 doubt, for at every return of new and full moon 

 we have high tides, while at half moon the tides 

 are low. The moon is in a line with the sun 

 both when about to appear as new moon, and 

 when at full moon. At those periods, therefore, the 

 attraction of the moon and the sun upon the 

 earth acts in one and the same direction, and the 

 united influence causes what are called the spring 

 tides. On the other hand, when the moon has 

 completed her first quarter, and her third quarter, 

 her attractive power at those points in her course 

 is exercised at right angles to that of the sun, and 

 thus, by preventing the waters from rising as 

 high as before, the neap or lower tides take 

 place. Nothing can be more obvious, therefore, 

 than the effect of solar and lunar attraction on 

 the phenomena of the tides. 



But, along with this general explanation, the 

 motion of the earth on its axis must, as already 

 hinted, be taken into view, and this will be 

 found greatly to influence the tidal phenomena. 



