Rivers in running into the sea present a great variety of interesting phenomena; many form _sand-banks_, as the Senegal and the Nile; others, like the Danube, run with such force into the sea, that one can for a certain space distinguish the waters of the river from those of the sea. The waters of the little river Syre in Norway are discernable for a considerable distance in the sea. It is only by a very large mouth, like that of the Loire, the Elbe, or the Plata, that a river can peacefully mingle with the sea. Rivers even of this nature, however, sometimes experience the superior influence of the sea, which repels the waters into their bed. Thus the Seine forms at its mouth a _bar_ of considerable extent; and the Garonne, unable to discharge with sufficient rapidity the waters which it accumulates in a kind of gulf between Bordeaux and its mouth, exhibits this aquatic mountain, stopped by the flow of the tide rolling backwards, inundating the banks, and stopping vessels in their progress both up and down. This phenomenon, termed the _Mascaret_, is only the collision of two bodies of water moving in opposite directions. The most sublime phenomenon of this kind which presents itself is that of the giant of rivers Orellana, called the river of the Amazons. Twice a day it pours out its imprisoned waves into the bosom of the ocean. A liquid mountain is thus raised to the height of one hundred and eighty feet; it frequently meets the flowing tide of the sea, and the shock of these two bodies of water is so dreadful that it makes all the neighboring islands tremble; the fishermen and navigators fly from it in the utmost terror. The next day, or the second day after every new or full moon, the time when the tides are highest, the river also seems to redouble its power and energy; its waters and those of the ocean rush against each other like the onset of two armies. The banks are inundated with their foaming waves; the rocks drawn along like light vessels, dash against each other, almost upon the surface of the water which bears them on. Loud roarings echo from island to island. It has been said that the Genius of the River and the God of the Ocean contended in battle for the empire of the waves. The Indians call this phenomenon _Pororoca_. COMPARATIVE VIEW OF THE RIVERS OF THE WORLD. NORTH AMERICA.