WATER. 653 



tral Pacific, the height is two to four feet ; and at Tahiti, high tide 

 occurs always at noon. 



2. Translation character of the tidal waves. — The tidal waves which 

 succeed one another around the globe become appreciably trans- 

 lation or propelling waves on soundings ; and directly upon a 

 coast, especially along its deeper bays or inlets, they constitute a 

 force of great energy. The borders of all the continents and 

 islands feel this power and exhibit its effects. 



3. In-fiowing tidal currents. — The in-coming tide generally strikes 

 one part of a coast before another, owing to its trend with refer- 

 ence to the wave, and, consequently, has a progressing movement 

 along it. This is very marked on the shores of southern New 

 England. 



The tidal current becomes one of great strength where there are 

 narrow channels to receive and discharge the waters. 



The movement may have the violence of a river-torrent when 

 the entrance to bays is of a kind to temporarily dam up the waters 

 until the far-advanced tide has so accumulated them that they 

 overcome the resistance and pass on in a body. 



In the Bay of Fundy, the waters of the in-coming tide are raised 

 high above their natural elevation, so that as they advance they 

 seem to be pouring down a slope, making a turbid waterfall of 

 majestic extent and power, without foam. The tide at Bristol. 

 England, has a height of forty feet. 



In some cases the whole tide moves in all at once, in a few great 

 waves. This happens especially at the mouths of rivers where there 

 is obstruction from sand-bars, and other favoring circumstances 

 about the entrance. The phenomenon is called an eagre or bore. 

 The flow of the tides at the Bay of Fundy has something of the 

 character of an eagre. But the most perfect examples are afforded 

 at the mouths of the rivers Amazon, Hoogly (one of the mouths of 

 the Ganges), and Tsien-tang in China. In the case of the last- 

 mentioned river the wave plunges on like an advancing cataract, 

 four or five miles in breadth and thirty feet high, and thus passes 

 up the stream, to a distance of eighty miles, at a rate of twenty-five 

 miles an hour. The change from ebb to flood tide is almost instan- 

 taneous. Among the Chusan Islands, just south of the bay, the 

 tidal currents run through the funnel-shaped firth with a velocity 

 of sixteen miles an hour. (Macgowan.) ' 



In the eagre of the Amazon, the whole tide passes up the stream 

 in five or six waves, following one another in rapid succession, and 

 each twelve to fifteen feet high. 



4. Oui-jlowiny currents. — The ebbing tide causes an out-flowing 



