THE TIDES. 109 



the first time we trod the beach and picked up 

 the shells and pebbles or ran with youthful glee 

 " along the golden sand ? " Do we not picture to 

 ourselves the huge delight with which we saw the 

 flowing tide gradually advance over the far extend- 

 ing and level sands, covering the boulders festooned 

 with algae that were here and there scattered over 

 it, till at last they were all submerged ; and how 

 again we watched with intense interest the ebbing 

 waves as they retreated once more, permitting us 

 with naked feet to ramble over the wet expanse 

 of newly covered sand, to search for some fancied 

 treasure that the sea might have left behind? 

 How pleasant, how charming, were it possible in 

 mature years, to look with the wonder and delight 

 of childhood on those natural phenomena which 

 in the fresh morning of life filled us with those 

 strange emotions with which we behold novel and 

 marvellous things ! 



The theory of the tides comprehends several 

 problems which are very abstruse, in consequence 

 of the number and variety of circumstances to be 

 taken into account. We require not only to con- 

 sider the action of the sun and the moon upon 

 the earth and the ocean, but the modifications of 

 this action arising from the position of the earth 

 in relation to the sun and moon, the influence of 

 the diurnal motion of the earth on its axis, as 

 well as its form and density, the figure of con- 

 tinents, the position of islands, the irregularities 

 occasioned by the character of the bottom of the 

 sea, and the laws of motion in fluid bodies and 



