00000358 |
Previous | 358 of 595 | Next |
|
small (250x250 max)
medium (500x500 max)
Large
Extra Large
large ( > 500x500)
Full Resolution
All (PDF)
|
THE MAGNETIC POLES. 327
terrestrial equator to the east of the Carolinas, traverses the islands of
Sunda, Hindoostan, Ethiopia, and Soudan, then passes to the south of the
equinoctial line not far from the island of St. Thomas, and lies in America
above Brazil and Peru. We may say generally that the magnetic equator
curves toward the north in the continents-of the Old World, and toward
the south in the New World. At the present time this line is slowly moving its points of intersection ofthe terrestrial equator from east to west.
The two magnetic poles occupy in relation to the earth's axis a position
quite oblique, since one is situated in the American polar archipelago,
while the other is found under the meridian of Australia. It results from
this, that the currents are themselves propagated obliquely to the surface
ofthe globe. Instead of advancing in the direction from north to south,
the mysterious force moves according to curves not parallel, which on the
Atlantic face of the earth bend toward the west, and on the opposite side
for the most part diverge toward the east. The lines of separation between
these two zones of western and eastern declination are the only parts of
the earth' where the compass points directly to the north. In order to indicate clearly the average direction of the magnetic needle for any year
whatever in various countries, other lines, called isogones, are drawn on
the map to the right and left of those marking no declination, where the
compass forms one and the same angle with the terrestrial meridian.
These curves, connecting all the points of the earth where the mean inclination ofthe needle remains sensibly equal, are much less regular than
the magnetic meridians. Some are directed from the north to the south,
others run partly from the east to the west; others, again, bend in the
form of circles and ovals.
At present, the line without declination which traverses the ancient
world passes to the -east of Spitzbergen, touches Russia in the environs
of Archangel, gains the Caspian depression by the valley of the Volga,
crosses Persia obliquely, then, after having coasted Hindoostan and the
islands pf Sunda, as if to mark the general outlines of the Asiatic continent, it is directed abruptly toward the southern magnetic pole across the
centre of Australia. To the west of this line, as far as the other side of
the shores of the continental group which constitutes Europe and Africa,
the declination of the compass toward the west increases gradually, and
then diminishes above the basin of the Atlantic, and is reduced to zero on
the eastern coasts of the New World. The second line without declination, which one might call the American line, descends from the magnetic
pole to the west of Hudson's Bay, traverses the great lakes, passes the environs of Philadelphia and Washington, and then curves round the Antilles, as the other line without declination is curved around the archipelago of Sunda, and cuts the extremity of Brazil from the mouths of the
Amazon to Rio de Janeiro, and crosses the Atlantic toward the south
pole. To the west of this line the deviation of the compass becomes
easterly, increasing rapidly above America, then much more slowly across
the Pacific, and diminishing to the east of China arid Siberia, so as to in-
| Title | The ocean, atmosphere, and life |
| Creator | Reclus, Elisée |
| Publisher | Harper |
| Place of Publication | New York |
| Date | 1873 |
| Language | eng |
| Type | Books/Pamphlets |
| Title | 00000358 |
| Type | Books/Pamphlets |
| Transcript | THE MAGNETIC POLES. 327 terrestrial equator to the east of the Carolinas, traverses the islands of Sunda, Hindoostan, Ethiopia, and Soudan, then passes to the south of the equinoctial line not far from the island of St. Thomas, and lies in America above Brazil and Peru. We may say generally that the magnetic equator curves toward the north in the continents-of the Old World, and toward the south in the New World. At the present time this line is slowly moving its points of intersection ofthe terrestrial equator from east to west. The two magnetic poles occupy in relation to the earth's axis a position quite oblique, since one is situated in the American polar archipelago, while the other is found under the meridian of Australia. It results from this, that the currents are themselves propagated obliquely to the surface ofthe globe. Instead of advancing in the direction from north to south, the mysterious force moves according to curves not parallel, which on the Atlantic face of the earth bend toward the west, and on the opposite side for the most part diverge toward the east. The lines of separation between these two zones of western and eastern declination are the only parts of the earth' where the compass points directly to the north. In order to indicate clearly the average direction of the magnetic needle for any year whatever in various countries, other lines, called isogones, are drawn on the map to the right and left of those marking no declination, where the compass forms one and the same angle with the terrestrial meridian. These curves, connecting all the points of the earth where the mean inclination ofthe needle remains sensibly equal, are much less regular than the magnetic meridians. Some are directed from the north to the south, others run partly from the east to the west; others, again, bend in the form of circles and ovals. At present, the line without declination which traverses the ancient world passes to the -east of Spitzbergen, touches Russia in the environs of Archangel, gains the Caspian depression by the valley of the Volga, crosses Persia obliquely, then, after having coasted Hindoostan and the islands pf Sunda, as if to mark the general outlines of the Asiatic continent, it is directed abruptly toward the southern magnetic pole across the centre of Australia. To the west of this line, as far as the other side of the shores of the continental group which constitutes Europe and Africa, the declination of the compass toward the west increases gradually, and then diminishes above the basin of the Atlantic, and is reduced to zero on the eastern coasts of the New World. The second line without declination, which one might call the American line, descends from the magnetic pole to the west of Hudson's Bay, traverses the great lakes, passes the environs of Philadelphia and Washington, and then curves round the Antilles, as the other line without declination is curved around the archipelago of Sunda, and cuts the extremity of Brazil from the mouths of the Amazon to Rio de Janeiro, and crosses the Atlantic toward the south pole. To the west of this line the deviation of the compass becomes easterly, increasing rapidly above America, then much more slowly across the Pacific, and diminishing to the east of China arid Siberia, so as to in- |
|
|
|
|
|
|
| B |
|
| C |
|
| G |
|
| H |
|
| M |
|
| T |
|
| U |
|
| Y |
|
|
|
