38 THE OCEAN WORLD. 



The tide is retarded every day about fifty minutes, the lunar day 

 being twenty-four hours fifty minutes of mean time. If, for instance, 

 it is high water to-day at two o'clock in the morning, that of the next 

 day will take place at fifty minutes past two. Low water does not 

 occur, however, at the half of the intermediate time ; the flux is more 

 rapid than the reflux : thus at Havre, Boulogne, and at corresponding 

 places- on this side of the Channel, it takes two hours and eight 

 minutes more in retiring ; at Brest, the difference is only sixteen minutes 

 more than the flux. The daily retardation of high water by the passage 

 of the moon in the meridian, at the equinoxes, is a constant quantity 

 for the same locality, which can be determined by direct observation. 



The height of the tide varies in the different regions of the globe, 

 according to local circumstances. The eastern coast of Asia and the 

 western coast of Europe are exposed to extremely high tides ; while in 

 the South Sea Islands, where they are very regular, they scarcely reach 

 the height of twenty inches. On the western coast of South America? 

 the tides rarely reach three yards; on the western coast of India 

 they reach the height of six or seven ; and in the Gulf of Cambay it 

 ranges from five to six fathoms. This great difference makes itself 

 felt in our own and adjoining countries : thus, the tide, which at 

 Cherbourg is seven and eight yards high, attains the height of fourteen 

 yards at Saint Malo, while it reaches the height of ten yards at 

 Swansea, at the mouth of the Bristol Channel, increasing to double 

 that height at Chepstow, higher up the river. In general, the tide 

 is higher at the bottom of a gulf than at its mouth. 



The highest tide which is known occurs in the Bay of Fundy, which 

 opens up to the south of the isthmus uniting Nova Scotia and New 

 Brunswick. There the tide reaches forty, fifty, and even sixty feet, 

 while it only attains the height of seven or eight in the bay to the north 

 of the same isthmus. It is related that a ship was cast ashore upon 

 a rock during the night, so high, that at daybreak the crew found 

 themselves and their ship suspended in mid-air far above the water ! 



In the Mediterranean, which only communicates with the ocean by a 

 narrow channel, the phenomenon of tides is scarcely felt, and from this 

 cause that the moon acts at the same time upon its whole surface, 

 which are not sufficiently abundant to increase the swelling mass of 

 waters formed by the moon's attraction; consequently, the swelling 



