The ocean is subdivided into portions, which are known by different
names, viz. the Atlantic, Pacific, Indian, Arctic or Northern, and
Antarctic or Southern oceans. The situation of these may be seen by
reference to the map of the world.
The Atlantic ocean varies in extent, from seven hundred to four
thousand miles in breadth from west to east, and is nine thousand miles
in length.
The Pacific ocean extends from north to south about eight thousand
miles, and from west to east about eleven thousand miles,—almost half
round the globe.
The Indian ocean extends from north to south about four thousand miles,
and from west to east varies from twenty-five hundred to six thousand
miles.
The Northern ocean is encircled by the coasts of the two continents.
Its greatest extent in one direction is computed to be three thousand
miles.
The Southern ocean lies south from the Atlantic, Pacific, and Indian
oceans, and surrounds the south pole.
The most remarkable phenomenon which occurs throughout the extent of
the ocean is the Maelstrom. This is a whirlpool by which a ship or any
thing which comes within the reach of the circling current is swallowed
up.
[Illustration: THE MAELSTROM.]
This whirlpool is in the Atlantic ocean, near the coast of Norway,
Europe.
MOUNTAINS, &c.
Mountains form the principal feature which presents itself on viewing
the surface of the _land_. These immense heights have their descents,
more or less steep, and their exteriors greatly diversified. Some
of them present a surface of naked and rugged rocks piled one upon
another; others show an abrupt and almost perpendicular surface, which
conveys to an observer an idea that the mountain has been cut from top
to bottom, so as to show the interior. Sometimes mountains seem, when
viewed from particular points, to show the form of the head of a tiger,
a bear, a man’s face, &c.
Some are composed of columns of basaltic rock, so regularly formed and
disposed that they seem to have been formed by art. The columns are
five or six sided, and appear to be divided into joints, at intervals
of about thirty feet. The Giant’s Causeway in Ireland, is a remarkable
instance of this natural curiosity.
[Illustration: GIANT’S CAUSEWAY.]
At this place there are ranges of these columns which extend into
the sea several hundred feet, and their tops present an almost level
surface of pavement.
Mountains have often large cavities in their interiors. In Norway,
Europe, there is a remarkable instance of a singular natural formation
of a mountain. Mount Torghat is pierced through with an opening one
hundred and fifty feet high, and three thousand long; at certain
seasons of the year the sun lights up the interior of this passage from
one end to the other.
Defiles or passes are narrow natural openings or roads through a chain
of mountains, and often form the only communication from one part of a
country to the other. There is a famous defile of this kind at the Cape
of Good Hope, Africa, which is called Holland’s Kloffe.
[Illustration: HOLLAND’S KLOFFE.]
This pass is so situated that it forms the _only_ communication from
the country of the Hottentots to the country beyond the mountains. One
hundred men could here successfully oppose the march of an immense army.
A defile sometimes forms the bed of a river, by which means the stream
passes through a chain of mountains. In the United States there is an
instance of this, where the opposite sides of the defile are connected
together at the top by a natural bridge of rock.
[Illustration: NATURAL BRIDGE, VIRGINIA, U.S.]
A PLATEAU is a plain of immense extent, which is formed of an extensive
surface of elevated land. Some plateaus are eight thousand feet above
the level of the sea. Lofty mountains often rise from these plateaus,
many of which are volcanic.
VOLCANO is a word taken from the name which the Romans gave to the
God of Fire. It now designates those mountains which are subject to
eruptions of fire, smoke, stones, and lava. The irruption of a volcano
is a most awful and majestic phenomenon. The earth is shaken, and
rumbling noises are heard, which sound like thunder. Smoke and fire
begin to issue from the top of the mountain.
Suddenly the fire becomes extinguished, and red-hot stones are thrown
out; then the crater is filled with a burning liquid called lava,
which looks like metal in a melted state. At last, the lava overflows
the sides of the crater, and runs down the sides of the mountain,
destroying every thing which lies in its path, and covering cities and
cultivated fields with a sea of burning matter. Sometimes the lava is
too heavy to be elevated to the summit, and bursts out from the side of
the mountain.
[Illustration: CRATER OF MOUNT ETNA.]
The cities Herculaneum and Pompeii, in Italy, were entirely destroyed,
A. D. 79, by an irruption of Vesuvius.
Herculaneum was discovered by digging away the ashes and lava, in the
year 1713. Pompeii was discovered about forty years afterwards.
The _height of mountains_ is measured from the level of the sea.
The highest mountains in the world are the _Himmaleh mountains_, in
Asia.
The second in point of elevation are the _Andes mountains_, in South
America; _Chimborazo_ is the highest peak.
The highest mountain in North America is _Mount Elias_,—in Europe,
_Mont Blanc_,—in Africa, the _Atlas mountains_.
A traveller in South America has lately asserted, that he has
discovered a mountain in Peru, which is higher than the Himmaleh
mountains in Asia. If this be a fact, it will probably soon be
confirmed by the testimony of other travellers.
The highest volcanic mountain in the world is _Cotopaxi_, one of the
Andes, in South America. Other celebrated volcanoes are _Popocatepetl_,
in North America,—_Mount Etna_, _Stromboli_, and _Vesuvius_, in
Europe,—and _Mount Hecla_, in Iceland.
Mountains are sometimes found standing alone; but generally many of
them are united in a _range_, or ridge, which extends many miles, and,
in some instances, through the whole extent of a continent.
In ascending mountains it will be found, that as you proceed towards
the top, the climate grows continually colder; and after passing beyond
the height of about 17,000 feet from the level of the sea, you arrive
at a region where snow and ice cover the ground during the whole year.
This contributes much to the coolness and salubrity of the climate of
countries where such high mountains are found.
[Illustration: COMPARATIVE HEIGHTS OF MOUNTAINS.]
───────────────────────────────────────────────────────────────
SCALE OF
FEET. ENGLISH
MILES.
───────────────────────────────────────────────────────────────
5 Highest Peak, ┐
26,000 Second Peak, │ Himmaleh
25,000 Third Peak, │ Mountains,
Fourth Peak, ┘_Asia_.
24,000
23,000
22,000
4 Chimborazo, _South America_.
21,000
20,000 Antisana, _South America_.
19,000 Mount Elias, _North America_.
Cotopaxi, _South America_.
18,000 Popocatepetl, _North America_.
Perpetual snow.
17,000 Mowna Roa, _Owhyhee_.
16,000 3 Mont Blanc, Alps, _Europe_.
15,000
14,000
Atlas, _Africa_.
13,000 Teneriffe, _Canary Isles_.
Rocky Mountains, _N. America_.
12,000 Mount Ararat, _Asia_.
11,000 2 Mt. Etna, _Sicily Islands, Europe_.
10,000 Quito city, _South America_.
9,000 Pyrenees, _Spain, Europe_.
Carpathian, _Austria, Europe_.
8,000 Apennines, _Italy, Europe_.
7,000
6,000 White Mts. _N. Hampshire, U. S._
1
5,000 Mount Hecla, _Iceland_.
Green Mountains, _Vermont, U. S._
4,000
3,000 Vesuvius, _Italy, Europe_.
Alleghany, _Virginia, U. States_.
2,000
Rock of Gibraltar, _Spain, Europe_.
1,000
Mount Tom, _Massachusetts, U. S._
500 St. Peter’s Church, _Rome, Italy_.
───────────────────────────────────────────────────────────────
LEVEL OF THE SEA.
───────────────────────────────────────────────────────────────
[Illustration: COMPARATIVE LENGTHS OF RANGES OF MOUNTAINS.]
═══════════════════════════════════════════════════════════════════
Dofrafeld Mountains, xxxxxxx COMPARATIVE LENGTHS
United States range, xxxxxxxxx OF RANGES
Atlas range, xxxxxxxxxxx OF MOUNTAINS.
Ural range, xxxxxxxxxx
Mountains of the Moon, xxxxxxxxxxxx
Altay range, xxxxxxxxxxxxxxxxxxxxxxxxxxxxx✠
Rocky Mountains, N. A. xxxxxxxxxxxxxxxxxxxxxxxxxxx✠
Andes, South America. xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx✠
│ │ │ │ │ │ │
══════════════════════════════╧═════╧═════╧═════╧═════╧═════╧═════╧═
MILES. 1000 2000 3000 4000 5000 6000 7000
✠(Whole length of the American range is 11,500 miles.)
Small streams are called _Brooks_, _Rivulets_, and sometimes _Creeks_.
In the study of the maps they are called _branches_ of rivers.
Many small streams, being formed in the mountainous and other elevated
parts of a country, flow together, and form a large current of water
which takes the name of a _river_, and is constantly augmented in its
course, by other _brooks_, &c. and by rain, until it discharges itself
into an ocean, sea, lake, or some other river.
The _length of rivers_ has not been so definitely ascertained as
the height of mountains. The length of the same river varies in the
statements of different geographers, and this difference is owing to
the principles on which their measurements are made, some measuring the
windings of the river, and others only the valleys through which they
flow.
The longest and largest river in the world is the AMAZON, in South
America. It is more than 150 miles wide at its junction with the
Atlantic ocean. The body of water is so great that it constantly flows
into the ocean, and is not affected by tides. The commotion caused by
the meeting of the tide and the current of the river, sometimes renders
navigation dangerous.
The longest rivers in North America are the MISSOURI and MISSISSIPPI.
The longest river in Asia is the KIAN KU. In Europe, the VOLGA. In
Africa, the NILE.
The Missouri flows into the Mississippi about 1300 miles from its
mouth, and is, in fact, the main river. And the length of the Missouri
is given, in the opposite table, from its source to the mouth of the
Mississippi.
The Missouri and Mississippi rivers, taken together, have no rival
in the world, for length of course, the size and number of their
tributaries, and the vast extent of country through which they flow.
The Mississippi is called by the native Indians the ‘Father of Waters,’
and the Missouri, the ‘Mother of Floods.’
[Illustration: COMPARATIVE LENGTHS OF RIVERS, ACCORDING TO THE BEST
AUTHORITIES.]
COMPARATIVE LENGTHS OF │ 4,500
RIVERS, ACCORDING TO │ │
THE BEST AUTHORITIES. │ │ 4,000
│ │
│ │ 3,500
│ │ │
│ │ │ │ 3,000
│ │ │ │ │ │
│ │ │ │ │ │ │ 2,500
│ │ │ │ │ │ │
│ │ │ │ │ │ │ │ 2,000
│ │ │ │ │ │ │ │ │ │
│ │ │ │ │ │ │ │ │ │ │ 1,500
│ │ │ │ │ │ │ │ │ ├─┘ │
│ │ │ │ │ │ │ │ │ │ │ │ 1,000
│ │ │ │ │ │ │ │ │ │ │ │
│ │ │ │ │ │ │ │ │ │ │ │ 500
│ │ │ │ │ │ │ │ │ │ │ │ │
──────────────────────────────┼─┼─┼─┼─┼─┼─┼─┼─┼─┼─┼─┼─┬─┤ SCALE OF
│ │ │ │ │ │ │ │ │ │ │ │ │ │ MILES
Connecticut, _U. States_, 410 │ │ │ │ │ │ │ │ │ │ │ │ │
Tennessee, _do._ 1,100 ┘ │ │ │ │ │ │ │ │ │ │ │ │
Ohio, _do._ 1,350 ──┘ │ │ │ │ │ │ │ │ │ │ │
Danube, _Europe_, 1,700 ────┘ │ │ │ │ │ │ │ │ │ │
Orinoco, _S. America_, 1,800 ──────┘ │ │ │ │ │ │ │ │ │
St. Lawrence, _N. Amer._ 2,000 ────────┘ │ │ │ │ │ │ │ │
Volga, _Europe_, 2,040 ──────────┘ │ │ │ │ │ │ │
La Plata, _S. America_, 2,600 ────────────┘ │ │ │ │ │ │
Nile, _Africa_, 2,687 ──────────────┘ │ │ │ │ │
Hoang Ho, _Asia_, 2,900 ────────────────┘ │ │ │ │
Kian Ku, _Asia_, 3,330 ──────────────────┘ │ │ │
Mississippi, _U. States_, 3,000 ────────────────────┘ │ │
Missouri, _U. States_, 4,400 ──────────────────────┘ │
Amazon, _S. America_, 4,500 ────────────────────────┘
Rivers are supplied with water principally from springs, and the
melting of snow upon high mountains. Mountains attract clouds around
their tops and sides, and by this means become saturated with water,
which, finding its way through the fissures of the rocks, forms
springs. In this manner probably all springs are formed, whether they
are found on mountains or plains. Heavy rains also augment the quantity
of water, and often after a heavy fall of rain, many rivers are so
swollen that the water overflows their banks, and the flood sweeps away
every thing that is within its reach.
The Mississippi is subject to inundations during the spring, and the
banks of the river being higher than the adjacent country, the water
never returns to the river, but seeks other channels. These inundations
greatly enrich the lands.
The banks or shores of rivers present very different appearances,
according to the formation of the land through which they pass. The
banks of some rivers are but little elevated above their level,
and slope gently down to the water’s edge; others flow through
rocky channels, and are walled on each side with high and almost
perpendicular precipices.
[Illustration: PASSAIC FALLS, NEW JERSEY, U. S.]
Sometimes a precipice occurs immediately across the course of a river,
and the water falling nearly perpendicularly over, forms a cataract or
falls.
They are often obstructed by rapids which render navigation difficult
and sometimes impracticable. A rapid is a gradual descent in the bed of
a river, where the current is swift, and the water shallow.
Some rivers suddenly disappear, by flowing into a chasm, and are lost
in the earth. Some of these again issue from the earth at a great
distance from where they disappeared.
Rivers present obstacles to the route of roads, and many expedients
have been invented by the ingenuity of man to obviate them. In many
places bridges are built of wood, stone or iron; and where the current
is too swift, or the channel too deep to permit a bridge to be built,
the passage is made in boats. But the most astonishing project that has
been undertaken for this purpose is the Tunnel under the river Thames,
at London, England. A road is here dug out _under_ the river, and is
nearly completed. A view of the work is given in the cut.
[Illustration: THAMES TUNNEL.]
The tunnel consists of two brick archways for carriages, and two foot
paths. The passages are divided by a line of arches, between the
pillars of which are placed gas lights. This undertaking was commenced
in the year 1825. The whole length is thirteen hundred feet, and each
archway is about fourteen feet in width. The thickness of the earth
between the bed of the river and the tunnel is about fifteen feet.
A country, possessed of large and navigable rivers, enjoys a great
blessing. They form a means of internal communication, by which the
productions of the inland country are brought to the city and seaport.
Their currents are made use of, by the aid of machinery, to manufacture
many of the necessaries and luxuries of life.
Many rivers whose waters are pure, afford water for the use of the
inhabitants of neighboring cities.
London and Westminster, England, are supplied from the New river;
the water is here brought thirty-eight miles through a canal. The
Schuylkill river in Pennsylvania, United States, supplies the city
Philadelphia with good and wholesome water, for the use of the
inhabitants.
[Illustration: VIEW OF THE PHILADELPHIA WATERWORKS.]
These works are ingeniously constructed at Fair Mount on
the eastern bank of the river. The water is raised by the
action of an engine, moved by the water power of the river
itself, and deposited in large reservoirs, from whence
it is conveyed by iron pipes to every part of the city.
The aggregate length of the pipes already laid exceeds
63 miles. Three reservoirs have already been constructed
which contain ten millions of gallons, and a fourth has
been commenced which will contain ten millions more, being
a quantity sufficient for the use of the city Philadelphia
ten days.