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DISTURBANCES OF THE SEA-LEVEL. 33
million billions of cubic yards, that is to say, the 560th part of the planet
itself. Sir John Herschel* gives much higher figures for the same volume
of water; but he has taken, as the basis of his calculation, the probable
maximum of the depth of the seas, that is to say, four English miles, more
than 3738 fathoms. We can not speak yet with certainty, but one day,
thanks to the new observations which are added every year to those
which science already possesses, it will be possible to give figures more
relatively exact for the depth of the marine abysses, and the mass of water that fills them. One thing is certain, that the highest part of the
continent raised above the surface of the waters is of much less elevation
than the depth of the sea; and we can estimate the land above the level
Of the sea at only about a fortieth part of the mass of waters. Besides
which, the land itself contains within it-an enormous quantity of water
united either chemically or mechanically with all rocks.
The water of the seas, urged by the force of gravitation, constantly
seeks its level, like the water of rivers and lakes. When, in consequence
of very rapid evaporation, or of a succession of tempests blowing from
the same quarter of the horizon, the surface of the sea is lowered in any
gulf, the waters from the adjacent parts mkh toward the impoverished
space, to fill the void. In the same way, when great rains, the swelling
of large rivers, or the action of winds have raised the level of the sea in
one point, this local swelling soon subsides, and its superfluity is dispersed over the surrounding surfaces. We may, therefore, consider the
mean height of the sea as the same in every ocean, since the. natural
movement of water tends ever to re-establish an equality of surface in all
parts where an accidental disturbance has occurred.
Nevertheless, the diversity of climates, of winds, and of currents, is
such, that certain seas, separated from one another by a narrow isthmus,
present permanently unequal levels. Thus several German engineers believe that they have established the fact that the Baltic Sea, into which a
great number of considerable rivers discharge themselves, is on an average some inches higher (?) than the North Sea.f In the same manner the
Atlantic, whose waters spread out on one side into the North Sea, and on
the other into the Mediterranean, would have a mean level scarcely higher than that of the two basins which it supplies; while the Black Sea
and the Gulf of Yenice, receiving, like the Baltic, several large rivers,
would, like the latter, be proportionably elevated. On the two sides of
the Isthmus of Suez the waters are also found at slightly unequal heights.
According to the engineer Bourdaloue, the mean level of the Red Sea at
Suez exceeds by 31^ inches that of the Mediterranean near Port Said; at
low tides the two sheets of water are perceptibly of the same level, while
at high-water the sea is sometimes higher by 3£ feet in the Bay of Suez
than at the northern extremity of the maritime canal. A similar difference, too, occurs between the Bay of Colon and the Gulf of Panama, and
* Physical Geography, p. 17.
t Woltmann; Von Hoff, Veranderungen der Erdoberfldche, t. iii., p. 328.
| Title | The ocean, atmosphere, and life |
| Creator | Reclus, Elisée |
| Publisher | Harper |
| Place of Publication | New York |
| Date | 1873 |
| Language | eng |
| Type | Books/Pamphlets |
| Title | 00000040 |
| Type | Books/Pamphlets |
| Transcript | DISTURBANCES OF THE SEA-LEVEL. 33 million billions of cubic yards, that is to say, the 560th part of the planet itself. Sir John Herschel* gives much higher figures for the same volume of water; but he has taken, as the basis of his calculation, the probable maximum of the depth of the seas, that is to say, four English miles, more than 3738 fathoms. We can not speak yet with certainty, but one day, thanks to the new observations which are added every year to those which science already possesses, it will be possible to give figures more relatively exact for the depth of the marine abysses, and the mass of water that fills them. One thing is certain, that the highest part of the continent raised above the surface of the waters is of much less elevation than the depth of the sea; and we can estimate the land above the level Of the sea at only about a fortieth part of the mass of waters. Besides which, the land itself contains within it-an enormous quantity of water united either chemically or mechanically with all rocks. The water of the seas, urged by the force of gravitation, constantly seeks its level, like the water of rivers and lakes. When, in consequence of very rapid evaporation, or of a succession of tempests blowing from the same quarter of the horizon, the surface of the sea is lowered in any gulf, the waters from the adjacent parts mkh toward the impoverished space, to fill the void. In the same way, when great rains, the swelling of large rivers, or the action of winds have raised the level of the sea in one point, this local swelling soon subsides, and its superfluity is dispersed over the surrounding surfaces. We may, therefore, consider the mean height of the sea as the same in every ocean, since the. natural movement of water tends ever to re-establish an equality of surface in all parts where an accidental disturbance has occurred. Nevertheless, the diversity of climates, of winds, and of currents, is such, that certain seas, separated from one another by a narrow isthmus, present permanently unequal levels. Thus several German engineers believe that they have established the fact that the Baltic Sea, into which a great number of considerable rivers discharge themselves, is on an average some inches higher (?) than the North Sea.f In the same manner the Atlantic, whose waters spread out on one side into the North Sea, and on the other into the Mediterranean, would have a mean level scarcely higher than that of the two basins which it supplies; while the Black Sea and the Gulf of Yenice, receiving, like the Baltic, several large rivers, would, like the latter, be proportionably elevated. On the two sides of the Isthmus of Suez the waters are also found at slightly unequal heights. According to the engineer Bourdaloue, the mean level of the Red Sea at Suez exceeds by 31^ inches that of the Mediterranean near Port Said; at low tides the two sheets of water are perceptibly of the same level, while at high-water the sea is sometimes higher by 3£ feet in the Bay of Suez than at the northern extremity of the maritime canal. A similar difference, too, occurs between the Bay of Colon and the Gulf of Panama, and * Physical Geography, p. 17. t Woltmann; Von Hoff, Veranderungen der Erdoberfldche, t. iii., p. 328. |
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