Livingstone, in the lake region of Central Africa, have so Ummer Rebia, and the Tensift, from the Atlas range, are
narrowed the space within which the sources of the Nile permanent rivers flowing across the fertile plain of Western
can exist, that, though no traveller has yet reached the Marocco, which they serve to irrigate. Next is the Wady
ultimate feeders of the great river, their position can now Draa, a water-course which has its rise on the inner slope of
be predicated almost with certainty. The limit of the the high land in Marocco, and which bends round through
Nile basin on the south is formed by the high mountains the Maroccan Sahara to the Atlantic, near the 28th parallel.
which rise to westward of the Albert Lake, and which divide Its channel, of not less than 500 miles in length, forms a long
between this great reservoir and the Tanganyika, extend-oasis in the partly desert country through which it flows,
ing eastward to the plateau of Unyamuezi, on the northern and water remains in its bed nearly throughout the year.
side of which the Victoria Nyanza lies. The ultimate A stretch of 1100 miles of waterless coast, where the
sources must then be the feeders of these great equatorial desert belt touches on the Atlantic, intervenes between
lakes, the Victoria and Albert. The river issuing from the Draa and the Senegal river, at the beginning of the
the former lake, at the Ripon Falls, 3300 feet above the pastoral belt in lat. 15° N.
sea, to join the northern end of the Albert Nyanza, may The Senegal rises in the northern portion of the belt of Senegal.
be considered as the first appearance of the Nile as a river. mountains which skirt the Guinea coast, and has a north-
At the Ripon Falls the overflow is from 400 to 500 feet in westerly course to the sea. During the rainy season it is
breadth, and the descent of 12 feet is broken in three navigable for 500 miles, from its mouth to the cataract of
places by rocks. Further down, where the river turns Feloo, for vessels drawing 12 feet of water, but at other
westward to join the Albert Lake, it forms the Karuma | times it is not passable for more than a third part of this
and Murchison Falls, the latter being 120 feet in height. distance. The Gambia has its sources near those of the Gambia.
From the Albert Lake, the Nile, called the Kir in this Senegal, and flows westward in a tortuous bed over the
part, begins its almost due northward course to the plain country, giving a navigable channel of 400 miles, up
Mediterranean, and has no further lake expansion. Be to the Falls of Barra Kunda. The Rio Grande, from the
tween the Albert and Gondokoro, in 5° N. lat., which lies same heights, is also a considerable river.
at 2000 feet above the sea, the Nile descends at least 500 The Niger is the third African river in point of area Niger.
feet in a series of rapids and cataracts. Beyond Gondokoro, of drainage and volume; it is formed by the union of
up to which point it is navigable, it enters the northern two great tributaries, the Quorra and Benue,—the former
lower land of Africa, which is here a region of swamps from the west, the latter from the country in the east of
and forests, and several tributaries join it from the west. the river basin. The Quorra, called the Joliba in its upper

The largest of these, named the Bahr-el-Ghazal, unites course, has its springs in the inner slope of the mountains
with the main stream below the 10th parallel; and, not which give rise to the Senegal and Gambia, not far from
much further on, a main tributary, the Sobat river, joins the Atlantic coast. At first its course is north-eastward to
the Nile from the unknown region which lies to the south as far as the city of Timbuctu, on the border of the desert
east. Hence, onward, the Nile is known as the Bahr-el-zone; then it turns due east, and afterwards south-east to
Abiad or White River. The two remaining great tribu- its confluence with the Benue, at a point 200 miles north
tary rivers descend from the high land of Abyssinia on the from the coast of the Gulf of Guinea. The chief tributary
east. The first of these, the Bahr-el-Azrek or Blue River, of the Quorra is the Sokoto river, coming from the elevated
its waters being pure in comparison with those of the Nile, country which forms the water-parting between the Niger
has its source near Lake Dembea or Tzana, through which basin and that of Lake Chad on the east, and its confluence
it flows, in the western side of the Abyssinian plateau, is near the middle of the portion of the channel of the
6000 feet above the sea ; forming a semicircular curve in Quorra which bends to south-east.
the plateau, the Blue Nile runs north-westward to the At a distance of about 100 miles from its sources, the
confluence at Khartum, 1345 feet above the sea. Between traveller Park, the first European who reached the Joliba,
this point and the union of the next tributary, the Nile found it flowing in a wide fertile valley, and navigated by
forms the cataract which is known as the sixth from its canoes which kept up a constant traffic. Above Timbuc-
mouth. In about 18° N. it is joined by the Atbara or tu' the commerce of the river is busily carried on in barges
Black River, the head stream of which is the Takkazze, of 60 to 80 tons burden; further on, where the river
flowing in a deep cut valley of the high land. This tribu- touches upon the desert belt in the most northerly portion
tary is named from the dark mud which it carries from the of its course, its fertile banks form the most marked con.
high land, brought down to it by streams which swell into trast to the arid desert lands beyond. From the confluence
rushing torrents in the rainy season. It is to these rivers of the Sokoto to the union with the Benue, the river course
that the fertility of Lower Egypt is mainly due, for each is only navigable after the rainy season, since at other
year a vast quantity of Abyssinian mud is borne down to be times rocks and shoals interrupt the passage. The sources
spread over the delta. Hence the Nile pursues its way of the Benue are unknown as yet, but it is believed to
in a single line through the dry belt of desert to the have its rise in the northern edge of the great plateau of
Mediterranean without a single tributary, descending by Southern Africa, almost due south of Lake Chad; its known
five cataracts, at considerable distances apart. The delta course is westward, and at the furthest point to which it was
of the Nile, in which the river divides into two main easily navigated by the traveller Baikie, nearly 400 miles
branches, from which a multitude of canals are drawn off, from its confluence with the Kawara or Quorra, it was still
is a wide low plain, occupying an area of about 9000 square half a mile in width and about 10 feet in average depth, flow-
miles. The most remarkable circumstance connected with ing through rich plains. From the confluence of the Quorra
the delta is the annual rise and overflow of the river, which and Benue the Niger has a due south course to its delta,
takes place with the greatest regularity in time and equality and the united river has an average width of about a mile.
in amount, beginning at the end of June, and subsiding At a distance of 100 miles from the sea, minor branches
completely before the end of November, leaving over the which enclose the delta separate from the main stream on
whole delta a layer of rich fertilising slime.

each side. The delta is much more extensive than that of The Sheliff in Algeria, and the Muluya in Eastern the Nile, and measures about 14,000 square miles of low Com the Marocco, are the chief streams flowing to the Mediterranean alluvial plain, covered with forest and jungle, and comlateau of from the high land of Barbary.

pletely intersected by branches from the main river, the arbary.

Passing round to the Atlantic system, the Sebu, the outmost of which reach the sea not less than 200 miles






apart. Unlike the Nile, the Niger possesses one main | Coanza, and its course is south-westward, forming the
channel through the centre of the delta, called at its mouth southern limit of the territory of Mossamedes. It is the
the Nun river.

most southerly river of the central fertile zones of Africa on
Old Calabar river, the Camaroon river, and the Gaboon, this side of the continent, and appears to be suitable for
are the best known of a number of wide inlets or estuaries navigation throughout the greater part of its length-rising
of the sea, which occur on the west coast immediately from 15 to 20 feet at times of flood, but having such a depth,
north of the equator; but these are merely the receptacles at its lowest stage, as to be only passable by canoes.
of a number of minor streams, not the mouths of great From the Cunene, in lat. 17° S., to the Orange river
rivers, as at one time supposed.

in 29° S., the dry belt of the South African desert zone
The Ogowai (pron. Ogowee) river, the delta of which intervenes, and there are no permanent rivers on the land
forms Cape Lopez, immedaitely S. of the equator, is a great sloping to the sea. The coast lands from the edge of the
stream which is believed to drain a large area of the forest plateau are, however, furrowed by numerous water-courses,
zone between the Niger and the Congo; as yet, its lower which are filled only after the occasional rainfalls.
coast is only known to a distance of 200 miles from the The Orange river also belongs for the greater part of its Orange

Above the delta the main stream of the river, named lower course to the water-courses of the arid belt, but it the Okanda, breaks through the edge of the plateau, and receives such a constant supply from its head streams, is joined by the Onango, a tributary from the coast range which descend from the high lands near the east coast of of the Sierra Complida. Below this confluence the river the continent, as to be able to maintain a perennial flow in is a mile and a half in average width, its depth varying from its channel, which, however, is so shallow as to be of no 15 to 50 feet. The delta is formed by the two main branches value for navigation. Its main head streams are the Vaal into which the Ogowai divides at about 30 miles from the and Nu Gariep or Orange, which rise on the opposite slopes coast, and is a swampy flat, covered with mangroves. of one of the summits of the Drakenberg range, called the

The Congo or Zaire must be considered the second river Mont aux Sources. After encircling the Orange River of Africa in point of area of drainage, and it is the first in Free State, these rivers unite near the centre of this part respect of the volume of water which it discharges to the of the continent to form the Orange, which continues westocean. There remains but little doubt that the head streams ward to the Atlantic, but without receiving any permanent of this vast river are those which supply the great lacustrine tributary. The chief water channels which periodically system discovered by Dr Livingstone in his recent journeys carry supplies to it from the south are Brak and the Great south and west of Lake Tanganyika. Through these lakes Hartebeeste; from the Kalahari region in the north come the river, which rises in the upland north of Lake Nyassa, the Molopo and Nosob channels. Midway between the named in different parts of its course the Chambeze, Lua- union of the head streams and the ocean the river forms pula, or Lualaba, flows in great bends to west and north- a great fall of 150 feet in height. ward, to where it passes into the unknown country still to The rivers which flow down from the terraces of the Drainage be explored in the heart of the continent. The Lualaba Cape Colony are numerous, but have little permanent depth to the has a great tributary named the Lufira, from the south; of water, shrinking almost to dryness excepting after rains, and it is almost certain that the Kassabi river, which when they become impetuous torrents; some have cut deep springs in the Mossamba Mountains, in the interior borders channels, much beneath the level of the country, and the of Angola, is also one of the feeders of this great river. banks of these cañons are choked with dense vegetation. The Guango river, rising in the same mountains, nearer Passing round to Natal and Zulu Land, the coast country is Angola, must also join the Congo lower down in its valley. well watered by frequent streams which descend from the At the furthest point on the Lualaba reached by Living- base of the cliff-wall of the Drakenberg; these have genestone, in about lat. 6° S. and long. 25° E., the great rally the character of mountain torrents, with rapid flow river had a breadth of from 2000 to 6000 yards, and could between high banks and changing volume, and are almost not be forded at any season of the year. Every circum- without exception closed at their mouths by sand bars, which stance connected with this river—its direction, the time of in most instances shut in considerable lagoons. One of these, its annual rising, and the volume of its water which could the lake of Santa Lucia, is more than 40 miles in length. be discharged by the Congo mouth alone-point to its The first large river of the Indian Ocean system is the Limpopo. identity with this river. The explorer Tuckey, who, in Limpopo or Crocodile river, so named from the great num1816, followed up the Congo from its mouth on the west ber of these animals found in its bed. Its basin lies coast further than any one, found it, above the cataracts centrally in the southern tropic, also in the desert belt, which it forms in breaking through the coast range, to and on this account it barely maintains a shallow flow of have a width of from 2 to 4 English miles, and with a water throughout the year. Its sources are in that part of current of from 2 to 3 miles an hour; and his statement the plateau edge in the Transvaal Republic which is known that at the lowest stage of its waters it discharges 2,000,000 as the Hooge Veldt and Magalies Berg; from this it forms of cubic feet of water per second, has been confirmed by a wide semicircular sweep to north-east and south, reaching more recent surveys. Forty miles out from its mouth the ocean not far north of Delagoa Bay, in 250 S. Its its waters are only partially mingled with that of the sea, chief tributary, the Olifant or Lepalule, has its rise in a and some nine miles from the coast they are still perfectly part of the Hooge Veldt which is nearer coast. Many fresh. The Congo is the only one of the large African of its minor tributaries in its lower course are periodical rivers which has any approach to an estuary, contrasting in streams known as sand rivers, only filled after heavy rains. this respect with those which have delta mouths.

The Zambeze is the great river of the pastoral belt of Zambeze. The Coanza, the most important river of Angola, in South Africa, and the fourth in point of size in the conrespect of its affording a navigable channel for 120 miles tinent, draining nearly 600,000 square miles. As far as from its mouth, rises in a broad valley formed by the its basin has yet been explored, the Zambeze has three Mossamba Mountains in the interior of Benguela, and head streams from the great water-parting ridge which curves north-westward to the ocean. Its upper course is extends from the Mossamba Mountains of inner Angola rapid, and its navigation only begins after the last of its to the high lands north of Nyassa Lake, about the 12th cataracts has been passed; the mouth is closed by a bar. parallel of S. latitude. There are the Lungebungo river The Cunene river has its rise in the opposite watershed of from the Mossamba Mountains, the Leeba river from the mountains, its springs being close to those of the Lake Dilolo, on the water-parting which separates be

Indian Ocean.


tween the Zambeze and the Kassabi river, and the Lize- | most varied directions. From the inner slopes of the
ambye or Jambaji, probably the main-source stream, plateau of Barbary numerous wadys take a direction to-
coming from the unknown lands south-west of the Cazembe's wards the great sand-belt of the Erg, in which they ter-
territory. From the union of these streams the general minate; a great series of channels appears to radiate from
course of the Zambeze is in two wide curves eastward, the higher portion of the Sahara, which lies immediately
through the plateau and over its edge to the Indian north of the tropic of Cancer and in about 5° E. of Green-
Ocean, in about 19° S. lat. From the north its main wich; another cluster radiates from the Mountains of
tributaries are the Kafue and Loangwa or Aruangoa rivers, Tibesti, in the eastern Sahara.
and the Shire river, flowing out of Lake Nyassa. Above Lake Chad, on the margin of the pastoral belt, is sup-
this point, on its middle course, where it forms the great plied by a large river named the Shari, coming from the
Victoria Falls, the Zambeze receives the Chobe from the moist forest country which lies nearer the equator; and the
north-west; and from southward numerous minor tribu- lake, which till recently was believed to have no outlet,
taries join its lower channel. The Zambeze forms a delta overflows to north-eastward, fertilising a great wady, in
with many mouths, the outmost of which are nearly 100 which the waters become lost by evaporation as they are
miles apart, and their entrances are generally barred by sand led towards the more arid country of the Sahara.
banks; but if these be passed, the main river is continuously The southern area of continental drainage is of much
navigable for 320 miles to the town of Teté, and its tribu- smaller extent, and occupies the space of the desert zone
tary the Shire may also be followed up for nearly 150 which lies between the middle of the Zambeze basin and
miles, to where its cataracts stop navigation. At the Damara Land. It centres in Lake Ngami, to which the
Victoria Falls the great river contracts from its general Tioge river flows from the pastoral belt on the north-
width of nearly a mile, to 60 or 80 feet, and plunges over west. Several water-courses from the high Damara Land
a height of 100 feet, into a remarkable zig-zag gorge rent also take a direction toward this lake. The river Zuga
in the hard basalt rocks.

carries off the overflow of Lake Ngami towards a series of Rovuma. The Rovuma, which has its chief tributaries from the salt lagoons which lie eastward near the edge of the

plateau edge on the eastern side of Lake Nyassa, is the plateau; but it becomes narrower and less in volume as it
next great river of the drainage to the Indian Ocean. It approaches these, and in some seasons scarcely reaches
has been navigated by Livingstone for 150 miles from the their bed.
coast, and formed part of his route in entering the con Smaller spaces of continental drainage exist at various
tinent on the journey from which he has not yet returned, points near the eastern side of the continent. One of
but its basin has not yet been explored.

these occupies the depressed area between the base of the Rufiji. Still farther north the mouths of a great river named Abyssinian highland and the Red Sea, and is properly a

the Rufiji are known, on the coast opposite the island of continuation of the Sahara desert belt beyond the inter-
Monfia, south of Zanzibar; but no part of its course has vening plateau. In this

space the Hawash river, descend-
yet been traced by any European.

ing from the plateau, terminates before reaching the sea. The Kingani and the Wami are two streams from the Another interior basin lies in the plateau between the plateau edge, in the country of Usagara, and reach the sea edge on which mountains Kenia and Kilima-njaro rise and in the channel formed by Zanzibar island. The Pangani the country east of the Victoria Lake, and includes several

river, further north, rises in the snowy mountain Kilima- salt lakes. It is probable that the great Tanganyika Lake Dana. njaro. The Sabaki and Dana, which embouch on the is the centre of a third basin of no outflow on this side of

opposite side of Formosa Bay, in 3° S., flow over the same the great plateau; and Lake Shirwa, south-east of the
coast plains, having their head springs in the spurs of Nyassa, constitutes a fourth.
Mount Kenia. The latter river might be navigated during The great lakes, which form such a prominent feature in Lakes.
the rainy season for 100 miles from the coast.

African hydrography, are found chiefly in the southern and
Juba.. The Juba river is the most considerable on the eastern eastern regions of the continent, but they are distributed

side north of the equator. It is believed to have its rise over all the systems of drainage. The Victoria and Albert
in the high lands inmediately south of Abyssinia, and its Lakes of the Nile basin are great seas of fresh water; and
general direction is south-eastward to the Indian Ocean ; if their extent should ultimately prove to be nearly that
but nothing is known of its higher course except by report which is at present believed, they rival the great Ame-
The ill-fated expedition under Baron von der Decken rican lakes for the place of the greatest expanse of fresh Nile lakes.
explored this river for about 180 miles upwards from its water on the globe. The former, the Victoria Lake, is at
mouth, but as yet no traffic is carried on by its means. an elevation of about 3300 feet above the sea ; and its

The Webbe or Haines river flows down from the high outline, as at present sketched on our maps, occupies an
lands in a direction nearly parallel to the Juba, a little area of not less than 30,000 square miles. The Albert
farther north, but its outlet on the coast is completely Lake, 2500 feet above the sea, is believed to have an
barred by sand dunes of from 400 to 500 feet in height, extent not far short of this. Lake Baringo, north-east of
behind which it forms a lagoon of varying extent. The the Victoria, is reported to be a great fresh lake, discharg-
desert zone is now again reached, and the water supply ing towards the Nile_by a river which is possibly the
fails. No permanent rivers reach the Red Sea from the Sobat tributary. Lake Tzana or Dembea, 60 miles in length,
Abyssinian highlands or from the heights of Nubia which at a level of 6000 feet above the sea, on the Abyssinian
continue these northward; the largest water-course is that plateau, is the only remaining great lake of the Nile basin,
of the Barca, which is periodically filled by its tributaries The great expansions of the Chambeze-Lualaba river, Congo
in the northern part of the Abyssinian plateau.

presumably belonging to the river Congo, are the only lakes. Areas of Turning now to the great areas of continental drainage, other considerable lakes of the Atlantic drainage. The continen- it is observed that in North Africa there is a vast space of highest of them, Lake Bangweolo or Bemba, is described tal drain

upwards of four millions of square miles, extending from as being 150 miles in length from east to west, and at an
the Nile valley westward to the Atlantic coast, and from elevation of 4000 feet; Lake Moero, the next, extends
the plateau of Barbary in the north to the extremities of through 60 miles ; Lakes Kamalondo or Ulenge, and the
the basin of Lake Chad in the uth, from which no single yet unvisited lakes of the same drainage, are described as
river finds its way to the sea. The whole of this space, of vast extent, and lie at an elevation of about 2000 feet
however, appears to be furrowed by water channels in the above the sea.




Zambeze Belonging to the drainage system of the Indian Ocean | mountains of the Cape Colony, and most remarkably in
Lake. are, Lake Nyassa, 1500 feet above the sea, and stretching the lofty summits of Mounts Kenia and Kilima-njaro,

meridionally over an area of nearly 9000 square miles in which rise on the plateau directly beneath the equator. The
the basin of the Zambeze; and Lake Samburu, a reported intensity of radiation and its influence upon the tempera-
lake of great extent, lying in the plateau edge north of ture are very great in Northern Africa; while in the day
Mount Kenia, and probably belonging to the basin of the time the soil of the Sahara rapidly absorbs the solar rays,
Juba river. The great Lake Tanganyika, upwards of 10,000 during the night it cools so rapidly that the formation of
square miles in area, and united by a broad channel with ice has often been known to occur.
Lake Liemba in the south, occupies a deep longitudinal The observed average temperatures of the extreme
basin, girt with mountains; it is 2800 feet above the sea months of the year at various points of Africa, from N. to
level. As yet no outlet has been discovered for this vast S., are given in the following table :-
lake, and the question whether it has or has not an over-
flowing river, is still undecided ; but its waters are not


Jan. July. perfectly fresh, the drainage to it is small, and the proba

Las Palmas, Can

67.1878 Continen- bility is that the Tanganyika is a continental lake. Lake

619 73.6 Kobbé, Darfur, ary Islands,

Ankobar, Abyssinia, 52.0 58.1 tal lakes. Shirwa, enclosed by mountains on the plateau edge south Santa Cruz, Tene

63.7 77-2 Elmina, Gold Coast, 79.7 76-7

riffe, east of Lake Nyassa, and 2000 feet above the sea, has

81.0 76.5


Funchal, Madeira, 63.5 72.5 Niger Mouth (5° 86.0 80-2 brackish water, and no outlet.

Casa Blanca, Ma


9' N.), Lake Chad, the greatest lake of the continental system


Gondokoro (5° n.), 89.3 78-5 of North Africa, is a shallow lagoon of very variable La Calle, Algeria,' | 54:6 78.4 || Zanzibar,

83.3 77.1 extent, with numerous islands : it lies at about 1100 feet Algiers,

Ascension I. (7° 55.8 | 76.3

77.0 75.0 (37° N.)

30' S.), :
above the sea; its waters are fresh and clear, and its over-

56.2 76-9 || St Helena,

73.6 65.8 flow is carried off to north-eastward by the wady named Constantine, ,

446 81.0 || Tete, on the Zam

82.972-4 Bahr-el-Ghazal.


54:2 | 98.9 beze (16° S.),
Lake Ngami, the corresponding lake in the southern

57.277.2 || Port Louis, Mau-


continental system, at an elevation of about 2900 feet,

Alexandria, Egypt, 57°4 | 78.5

St Denis, Bourbon, | 79.7 71.8 is also a shallow reedy lagoon, varying in extent according (30° N.)


Durban, Natal, . 74.262.4 to the season. The Zuga river carries off its surplus water to Kenneh,

62-4 943 Pietermaritzburg

71.4 55.2 Salt lakes. eastward. Salt lakes are of frequent occurrence in the areas Freetown, Sierra ,

(30° S.), Leone,

82.0 77.5 of continental drainage; perhaps the most remarkable of

Cape Town (34°S.), | 74.3 57.6 Kuka, Bornu

Stellenbosch, . 77.0 57.0 these is the Assal lake, which lies in a depression east of

75.683.8 (13° N.),

Swellendam, . 72.7 59.9 Abyssinia comparable with that of the Dead Sea, 600 feet beneath the level of the Red Sea; the Sebka-el-Faroon Africa is not much under the influence of the regular Winds or Schott Kebir, south of Tunis, is a great salt lagoon, 100 winds, except the monsoons of the Indian Ocean, the great miles in length, dried up in summer, when its bed is found movement of the atmosphere depending chiefly on the to be thickly encrusted with salt, and in winter covered oscillation of the continent beneath the sun during the seawith water to a depth of two or three feet. It lies several sons, as will be afterwards explained. The wind currents feet beneath the level of the Mediterranean.

over the whole continent have a prevailing direction from Climate. Africa lies almost entirely in the torrid zone, and is the the east. There are the trade winds, modified by inter

hottest continent of all. The greatest heat, however, is not ruptions of changing heat and elevation of the land surfound under the equator, since the whole of the central belt face. In the northern part of the Indian Ocean the year of the continent is protected by a dense covering of forest is divided between the south-west monsoon, blowing from vegetation, supported by the heavy rainfall, and has in March till September, away from Africa, towards the then consequence a more equable climate, but in the dry, bare heated continent of Asia; and the north-east monsoon, or exposed desert belts, which lie on the margins of the rather the normal trade wind, blowing towards the African tropics, the Sahara in the north and the Kalahari in the coasts, from October till February. It will be seen in the south, where the climate is extreme. The highest tempera- next paragraph, that the monsoons, although they extend ture is found throughout the Sahara, particularly in its only to about a third portion of the East African shores, eastern portions towards the Red Sea. In Upper Egypt have an extremely important bearing upon the physical and Nubia eggs may be baked in the hot sands; and the economy of the whole African continent. From hurricanes saying of the Arabs is, “in Nubia the soil is like fire Africa is nearly exempt, except in its south-eastern extremity, and the wind like a flame." The regions along the to which at times the Mauritius hurricanes extend. At Mediterranean and Atlantic coasts are rendered more tem rare intervals these have visited the east coast as far as perate by the influence of the sea. To the south of the Zanzibar. Northern Africa is much exposed to the hot Great Desert the temperature decreases, chiefly on account winds and storms from the Sahara, which are called in of the increasing moisture and protection of the land sur- Egypt Khamsin, in the Mediterranean Scirocco, Shume face from extreme heating by its tree growth, but also or Asshume in Marocco, and Harmattan on the west coasts because of the greater elevation of the land as the great of the Sahara and in the countries bordering on the Gulf southern plateau is approached. Both on account of its of Guinea. These always blow directly across the coast elevation and its narrower form, which gives greater access from the interior, and seem to move round the compass to the equalising influence of the surrounding ocean, the during the year, beginning in Egypt in April, in Algeria southern half of the African continent has a less high in July, in Marocco in August, in Senegambia in November. temperature than the northern, though the same gradations Similar dry electrical winds are experienced in the Kalahari of climate outward from the centre belt are clearly marked | desert in the south. Whirlwinds, frequently carrying sand in each division. Regular snowfall does not occur even up into the atmosphere, are of frequent occurrence in in the most southern or northern regions; and this pheno- these deserts, and are also known in the dry region of menon is only known in the most elevated points of the Unyamuezi, between Zanzibar and the Tanganyika, and in continent, as in the Atlas Mountains in the north, the the Limpopo basin farther south. Extreme heat and drysummits of which retain patches of snow even in summer, ness are the characteristics of these winds, which, raising in the Abyssinian peaks, in the highest points of the the sand, filling the air with dust, and prodigiously favour

ing the powers of evaporation, are often fatal to the vege- | in September and October. Whils the north-east mon- In the

table and animal creation in the regions visited by them. soon is blowing the sky remains of a cloudless blue. In interior. Rains

In Africa the dependence of the winds and rains upon the interior of the continent, between these tropical coasts, within the the movement of the land beneath the sun is more clearly the rainy seasons appear rather to precede than follow the tropics.

marked than in any other intertropical region of the globe. advancing sun. In the region of the central Zambeze the

The high temperature caused by the vertical heat of the greater rains last through February, March, and April, sun over a particular area induces an indraught of air to the lesser occurring in October and November. The worst that place, an ascending current is produced which carries droughts are experienced in December and January. up with it the warm and moist air; condensed in the Nearer the centre of the continent the two rainy seasons higher regions of the atmosphere, the moisture falls as become so lengthened as almost to merge into one period rain, and the condensation makes way for a further in- of rains, extending over about eight months of the year. draught. It is thus that in Africa the winds and rains In the newly-explored country south-west of the Tanganyika, follow as a rule the pendulating movement of the continent Dr Livingstone found that the rains began in October, and beneath the sun, and the rainy season of any space begins that the last showers fell in May; but there is probably a almost immediately after the sun has reached its zenith. drier period between these limits. At the Tanganyika Lake Between the tropics and the equator the sun comes twice the rainy season begins in September, lasting till May, and to the zenith of each belt during the year, at the tropical | the same rainy reason has been observed in the interior lines the sun is only once in the zenith; thus it follows country of the west coast immediately north of tho that a double rainy season is observed in all places lying equator. Between these points, in Manuyema country, in the central belt of the tropics, and a single rainy season Dr Livingstone found that the rains continued till July, in those which are nearer the skirts of the zone. These or almost through the year. Northward in the interior the wet and dry seasons correspond to the cooler and hotter rainy seasons are again clearly divided into a greater and periods of the year, and take the place of the summer and lesser, and in the regions west of the Upper Nile between winter of the temperate regions. Various circumstances 50 and 10° N. lat., the stronger rains occur from August tend to interfere with and modify the working of this till October, the weaker come with the northing sun in general rule of the rotation of seasons. In Southern April and May. The plateau of Abyssinia, rising high Africa that rainy season which follows the apparent move above the general level of the north of Africa, and interment of the sup northward, is greater than that which cepting and condensing the moist winds, has also a double ensues after his passage south, since in the former case the rainy season,-a greater from June to September, when the winds are drawn inwards from the ocean and carry greater sun is passing southward; a lesser in February and April, quantities of moisture, whereas in the latter the winds are with the northing sun. The rainy seasons in Central Africa drawn from the land north of the equator, and their mois are ushered in and accompanied by violent thunderstorms

ture is already in great part spent. In the northern and and by occasional falls of hail. The quantity of the rainOn the eastern regions of Africa the winds and rains are governed fall, which is excessive in the regions near the equator,

as much by the heating and cooling of the Asiatic con diminishes rapidly to north and south of this belt as tho tinent as by that of Africa itself, but in the central and dry regions on the borders of the tropics are approached. western portions of the continent the rule is well exem The Sahara, and also the Kalahari of Southern Africa, are plified. Thus in Damara Land, bordering on the southern almost rainless regions, but wherever a sufficient elevation tropic, there is one short rainy season from February till occurs to intercept a cooler stratum of the atmosphere, rain April, beginning only with the northing sun; at Loanda is not wanting, even in the midst of the Great Desert. A in Angola the greater rains last from February till May, striking instance of this is related by Mr Richardson. That the lesser rainy season, when the sun has passed this place traveller relates that when on the borders of the mountain going south, occurs in November only At Annobon knot of “ Aïr, in about latitude 19° N., on the 30th Sept. island, surrounded by wide sea, April and May are the 1850, there was a cry in the encampment, 'Tho wady is rainy months of the northing sun, October and November coming.' Going out to look, I saw a broad white sheet of of the southing: The Guinea coast, facing the sea to foam advancing from the south between the trees of the southward, has its greater rainy season from March to valley. In ten minutes after a river of water came pouring June, when the northing sun draws the ocean winds on to along, and spread all around us, converting the place of our the coast; and its lesser rains occur in October and encampment into an isle of the valley. The current in its November, when the sun has passed southward from the deepest part was very powerful, capable of carrying away land. Nearing the northern tropical line, the coast-land sheep and cattle, and of uprooting trees. This is one of from Sierra Leone to the Senegal river has a simple wet the most interesting phenomena I have witnessed during and dry season during the year.

my present tour in Africa. The scene, indeed, was perOn the eastern coast-land the rains are more dependant on fectly African. Rain had been observed falling in the the direction of the monsoon winds; about the mouths of the south ; black clouds and darkness covered that zone of the Zambeze and on the Mozambique coast the rains begin in heavens, and an hour afterwards came pouring down this November, after the north-east monsoon wind has set in over river of water into the dry parched-up valley.” the northern part of the Indian Ocean, bringing with it the The causes of want rainfall in the vast region of the Dry revapours drawn from the sea to condense on the coast slopes. Sahara appear to be mainly these—that the winds advanc- gions.

The rains continue here till March, when the south-westing towards it come from a cooler and moister to a warmer monsoon begins to blow away from the land towards the and drier region, indeed to the hottest and driest of all, then heated surface of Asia. At Zanzibar there is a double and so are constantly losing in moisture and gaining in rainy season, a stronger in the months of March, April, temperature as they approach ; the high plateau of and May, with the northing sun, beginning immediately Abyssinia forms an effective screen from the winds of the after the south-west monsoon has set in, and a weaker in Indian Ocean, wringing out their moisture before the September and October with the southing sun. Under Sahara is reached, and on the Atlantic side the north-east the equator on the east coast the rains begin in April with trade wind constantly blows away from the land ; a the south-west monsoon, continuing till June, and during barrier of mountains also deprives the Sahara of min from this period the sky is obscured by heavy clouds. The the south-west. Another cause of dryness is the low level second rainy season here is only marked by a few showers of great areas of the Sahara. We have seen that wherever


« ElőzőTovább »