00000105 |
Previous | 105 of 595 | Next |
|
small (250x250 max)
medium (500x500 max)
Large
Extra Large
large ( > 500x500)
Full Resolution
All (PDF)
|
92 THE OCEAN.
The Red Sea is therefore only an immense basin of evaporation, and the
annual loss is all the greater that*the rays of the sun shine almost always
from a cloudless sky. The portion of fluid transformed into vapor is estimated at about eight-tenths of an inch per 24 hours—that is to say,
nearly 23 feet per year; so that if the gulf was completely closed, the water, whose mean depth does not exceed 220 fathoms, would be entirely
dried up in the space of sixty years. Owing to their higher level, the
waves of the Indian Ocean are carried into the Arabian Gulf by the Straits
of Babel-Mandeb; and this flow, superficial or submarine, must make itself
felt with all the more force, because during eight months of the year the
winds blow from the north to the south precisely in the axis of the Red
Sea, and would thus tend to empty the gulf, if the laws of gravity per
mitted. But whatever be the swiftness of the current coming from the
Indian Ocean, a portion of its water evaporates on the way, and, in consequence, the liquid mass, diminished by a certain quantity from evaporation, must become Salter and Salter in proportion as it advances to the
north. In fact, it has been established by direct analyses that the quantity of salt contained in the same volume of water increases gradually
from Aden to Suez. From a little more than 39 parts in a 'thousand at
the entrance to the gulf, it rises to 41 and even 43 parts in the thousand
at the northern extremity.* Dr. Buist, a scholar of Bombay, has calculated that if the Red Sea did not return to the ocean the salt that is
concentrated there in consequence of evaporation, it would end in being
changed into a solid mass of salt in a space of time certainly less than
three thousand years, and perhaps in only fifteen or twenty centuries,f
Now the Red Sea has already existed for thousands and thousands of
years, and its waters (more salt than those of other seas, it is true) are
still very far from being in a state of saturation. We therefore come
to this inevitable conclusion, that a very salt submarine current flows
through the Straits of Babel-Mandeb into the Indian Ocean in an opposite direction, and below the superficial current which supplies the Arabian Gulf. As in houses each door serves at the same time as a passage
for two contrary currents—that of the warmer and lighter air which escapes above, and that of the colder and heavier air penetrating below—so
in the seas each strait is traversed by two streams different in temperature and in their saline contents.
All these phenomena of exchange, which occur in such a striking manner at the entrance to the Red Sea, the Mediterranean, and the Baltic,
are reproduced in the vast space of the seas wherever the equilibrium of
level, warmth, or saltness is disturbed by any cause whatever. Thus
the Atlantic, much better supplied than the South Sea as regards rains
and affluents, is nevertheless not more elevated; and on its side the Pacific does not contain a greater quantity of salt than the other oceans.
On all parts of the planet, seas bathing the shores of countries most diverse in appearance and geological formation have a tendency to resem-
* See p. 36. f Maury, Geography of the Sea.
| Title | The ocean, atmosphere, and life |
| Creator | Reclus, Elisée |
| Publisher | Harper |
| Place of Publication | New York |
| Date | 1873 |
| Language | eng |
| Type | Books/Pamphlets |
| Title | 00000105 |
| Type | Books/Pamphlets |
| Transcript | 92 THE OCEAN. The Red Sea is therefore only an immense basin of evaporation, and the annual loss is all the greater that*the rays of the sun shine almost always from a cloudless sky. The portion of fluid transformed into vapor is estimated at about eight-tenths of an inch per 24 hours—that is to say, nearly 23 feet per year; so that if the gulf was completely closed, the water, whose mean depth does not exceed 220 fathoms, would be entirely dried up in the space of sixty years. Owing to their higher level, the waves of the Indian Ocean are carried into the Arabian Gulf by the Straits of Babel-Mandeb; and this flow, superficial or submarine, must make itself felt with all the more force, because during eight months of the year the winds blow from the north to the south precisely in the axis of the Red Sea, and would thus tend to empty the gulf, if the laws of gravity per mitted. But whatever be the swiftness of the current coming from the Indian Ocean, a portion of its water evaporates on the way, and, in consequence, the liquid mass, diminished by a certain quantity from evaporation, must become Salter and Salter in proportion as it advances to the north. In fact, it has been established by direct analyses that the quantity of salt contained in the same volume of water increases gradually from Aden to Suez. From a little more than 39 parts in a 'thousand at the entrance to the gulf, it rises to 41 and even 43 parts in the thousand at the northern extremity.* Dr. Buist, a scholar of Bombay, has calculated that if the Red Sea did not return to the ocean the salt that is concentrated there in consequence of evaporation, it would end in being changed into a solid mass of salt in a space of time certainly less than three thousand years, and perhaps in only fifteen or twenty centuries,f Now the Red Sea has already existed for thousands and thousands of years, and its waters (more salt than those of other seas, it is true) are still very far from being in a state of saturation. We therefore come to this inevitable conclusion, that a very salt submarine current flows through the Straits of Babel-Mandeb into the Indian Ocean in an opposite direction, and below the superficial current which supplies the Arabian Gulf. As in houses each door serves at the same time as a passage for two contrary currents—that of the warmer and lighter air which escapes above, and that of the colder and heavier air penetrating below—so in the seas each strait is traversed by two streams different in temperature and in their saline contents. All these phenomena of exchange, which occur in such a striking manner at the entrance to the Red Sea, the Mediterranean, and the Baltic, are reproduced in the vast space of the seas wherever the equilibrium of level, warmth, or saltness is disturbed by any cause whatever. Thus the Atlantic, much better supplied than the South Sea as regards rains and affluents, is nevertheless not more elevated; and on its side the Pacific does not contain a greater quantity of salt than the other oceans. On all parts of the planet, seas bathing the shores of countries most diverse in appearance and geological formation have a tendency to resem- * See p. 36. f Maury, Geography of the Sea. |
|
|
|
|
|
|
| B |
|
| C |
|
| G |
|
| H |
|
| M |
|
| T |
|
| U |
|
| Y |
|
|
|
