“That lions exist in the desert,” says M. Carette, “is a myth popularised by the dreams of artists and poets, and has no foundation but in their imagination. This animal does not quit the mountains where it finds shelter, food, and drink. When the traveller questions the natives concerning these wild beasts, which Europeans suppose to be their companions in the desert, they reply, with imperturbable sang froid, ‘Have you, then, lions in your country which can drink air and eat leaves? With us lions require running water and living flesh; and therefore they only appear where there are wooded hills and water. We fear only the viper (lefa), and, in humid spots, the innumerable swarms of mosquitoes which abound there.[[DK]]’”
While Dr. Oudney, in his long journey from Tripoli to Lake Tschad, estimated the elevation of the Southern Sahara at 1637 feet, and German geographers even ventured to add an additional thousand feet, Fournel, the engineer, has, by careful barometric measurements, based on corresponding observations, made it tolerably probable that a part of the northern desert is below the sea’s level. The portion of the desert which is now called “Le Zahara d’Algérie,” advances to the chains of hills of Metlili and el-Gaous, where lies the most northern of all the Oases, el-Kantara, fruitful in dates. This low basin, which reaches the parallel of 34° lat., receives the radiant heat of a stratum of chalk, inclined at an angle of 65° towards the south, and which is full of the shells of Inoceramus[[DL]]. “Arrived at Biscara (Biskra),” says Fournel, “an indefinite horizon, like that of the sea, lay spread before us.” Between Biscara and Sidi Ocba the land is only 243 feet above the sea’s level. The inclination increases considerably towards the south. In another work[[DM]], where I have brought together all the points that refer to the depression of some portions of continents below the level of the sea, I have already noticed that, according to Le Père, the bitter lakes (lacs amers) on the isthmus of Suez, when they have but little water, and, according to General Andréossy, the Natron lakes of Fayoum, are also lower than the level of the Mediterranean.
Among other manuscript notices of M. Fournel, I possess a geognostic vertical profile, with all the inflexions and inclinations of the strata, representing the surface the whole way from the coast near Philippeville to a spot near the Oasis of Biscara in the Desert of Sahara. The direction of the line on which the barometric measurements were taken is south 20° west; but the points of elevation determined are projected, as in my Mexican profiles, on a different plane, one from N. to S. Ascending uninterruptedly from Constantine, whose elevation is 2123 feet, the highest point is found between Batnah and Tizur, at only 3581 feet. In the part of the desert which lies between Biscara and Tuggurt, Fournel has succeeded in digging a series of artesian wells[[DN]]. We learn from the old accounts of Shaw, that the inhabitants of the country were acquainted with a subterranean supply of water, and related fabulous tales of a “sea under the earth (bahr tôhl el-erd).” Fresh waters, which flow between clay and marl strata of the old chalk and other sedimentary formations, under the action of hydrostatic pressure, form gushing fountains when the strata are pierced[[DO]]. The phenomenon of fresh water being often found near beds of rock salt, need not surprise the geognosist, acquainted with mining operations, since Europe offers many analogous phenomena.
The riches of the desert in rock-salt, and its employment for purposes of building, have been known since the time of Herodotus. The salt zone of the Sahara (zone salifère du désert) is the most southern of the three zones which pass through Northern Africa from south-west to north-east, and is believed to be connected with the beds of rock-salt in Sicily and Palestine described by Friedrich Hoffman, and by Robinson[[DP]].
The trade in salt with Sudan, and the possibility of cultivating the date-tree in the many Oasis-like depressions, caused probably by earth-slips in the beds of tertiary chalk or Keuper-gypsum, have equally contributed to animate the desert, at various parts, by human intercourse. The high temperature of the air, which renders the day’s march so oppressive across the Sahara, makes the coolness of the night (of which Denham and Sir Alexander Burnes frequently complained in the African and Asiatic deserts) so much the more remarkable. Melloni[[DQ]] ascribes this coolness (which is probably produced by the radiation of heat from the ground), not to the great purity of the heavens (irraggiamento calorifico per la grande serenità di cielo nell’ immensa e deserta pianura dell’ Africa centrale), but to the extreme calm, and the absence of all movement in the air throughout the whole night[[DR]].
The river Quad-Dra (Wadi Dra), which is almost dry the greater part of the year, and which, according to Renou[[DS]], is one-sixth longer than the Rhine, flows into the Sahara in 32° north latitude, from the southern declivity of the Atlas of Morocco. It runs at first from north to south, until in 29° north lat., and 5° 8′ west long., it deflects at right angles to the west, and traversing the great fresh-water lake of Debaid, flows into the sea at Cape Nun, in lat. 28° 46′, and long. 11° 8′. This region, which was first rendered celebrated by the Portuguese discoveries of the fifteenth century, and whose geography has subsequently been shrouded in the deepest obscurity, is now known on the coast as the country of the Scheik of Beirouk (whose dominions are independent of the Emperor of Morocco). It was explored, in the months of July and August, 1840, by the French Count, Captain de Bouet-Villaumez, under the orders of his government. From manuscript and official reports it would appear that the mouth of the Quad-Dra is at present so much blocked up by sand as to have an open channel of only about 190 feet. The Saguiel-el-Hamra,—still very little known,—which comes from the south, and is supposed to have a course of at least 600 miles, flows into the same mouth at a point somewhat farther eastward. The length of these deep, but generally dry, river-beds is astonishing. They are ancient furrows, similar to those which I observed in the Peruvian desert at the foot of the Cordilleras, between the latter and the shores of the Pacific. In Bouet’s manuscript narrative[[DT]], the mountains which rise to the north of Cape Nun are estimated at the great height of 9,186 feet.
It is generally supposed that Cape Nun was discovered in 1433 by the Knight Gilianez, despatched under the order of the celebrated Infante, Henry, Duke of Viseo, and founder of the Academy of Sagres, which was presided over by the pilot and cosmographer, Mestre Jacomè, of Majorca; but the Portulano Mediceo,—the work of a Genoese navigator of the year 1351,—already contains the name of “Cavo di Non.” The doubling of this Cape was as much dreaded as has been since then the passage round Cape Horn; although it is only 23′ north of the parallel of Teneriffe, and might be reached by a few days’ sail from Cadiz. The Portuguese adage, “Quem passa o Cabo de Num, ou tornarà ou não,” could not intimidate the Infante, whose heraldic French motto of “Talent de bien faire,” well expressed his noble, enterprising, and vigorous character. The name of this Cape, which has long been supposed to originate in a play of words on the negative particle, does not appear to me to be of Portuguese origin. Ptolemy placed on the north-west coast of Africa a river Nuius, in the Latin version Nunii ostia. Edrisi refers to a town, Nul, or Wadi Nun, somewhat further south, and about three days’ journey in the interior, named by Leo Africanus Belad de Non. Several European navigators had penetrated far to the south of Cape Nun before the Portuguese squadron under Gilianez. The Catalan, Don Jayme Ferrer, in 1346, as we learn from the Atlas Catalan, published at Paris by Buchon, had advanced as far as the Gold River (Rio do Ouro), in 23° 56′ north lat.; while the Normans, at the close of the fourteenth century, reached Sierra Leone in 8° 30′ north latitude. The merit of having been the first to cross the equator in the Western Ocean incontrovertibly belongs, like so many other great achievements, to the Portuguese.
[17]. p. 7.—“As a grassy plain, resembling many of the Steppes of Central Asia.”
The Llanos of Caracas, of the Rio Apure and the Meta, which are the abode of numerous herds of cattle, are, in the strictest sense of the word, grassy plains. The two families of the Cyperaceæ and the Gramineæ, which are the principal representatives of the vegetation, yield numerous forms of Paspalum (Paspalum leptostachyum, P. lenticulare), of Kyllingia (Kyllingia monocephala (Rottb.), K. odorata), of Panicum (Panicum granuliferum, P. micranthum), of Antephora, Aristida, Vilfa, and Anthisteria (Anthisteria reflexa, A. foliosa). It is only here and there that any herbaceous dicotyledon, as the low-growing species of Mimosa intermedia and M. dormiens, which are so grateful to the wild horses and cattle, are found interspersed among the Gramineæ. The natives very characteristically apply to this group the name of “Dormideras,” or sleepy plants, because the delicate and feathery leaves close on being touched. For many square miles not a tree is to be seen; but where a few solitary trees are found, they are, in humid districts, the Mauritia Palm, and, in arid spots, a Proteacea described by Bonpland and myself, the Rhopala complicata (Chaparro bobo), which Willdenow regarded as an Embothrium; also the useful Palma de Covija or de Sombrero; and our Corypha inermis, an umbrella palm allied to Chamærops, and used by the natives for the covering of their huts. How much more varied and rich is the aspect of the Asiatic plains! In a great portion of the Kirghis and Kalmuck Steppes which I have traversed (extending over a space of 40 degrees of longitude), from the Don, the Caspian Sea and the Orenburg-Ural river Jaik, to the Obi and the Upper Irtysch, near the Lake Dsaisang, the extreme range of view is never bounded by a horizon in which the vault of heaven appears to rest on an unbroken sea-like plain, as is so frequently the case in the Llanos, Pampas, and Prairies of America. I have, indeed, never observed anything approaching to this phenomenon, excepting, perhaps, where I have looked only towards one quarter of the heavens, for the Asiatic plains are frequently intersected by chains of hills, or clothed with coniferous woods. The Asiatic vegetation, too, in the most fruitful pasture lands, is by no means limited to the family of the Cyperaceæ, but is enriched by a great variety of herbaceous plants and shrubs. In the season of spring, small snowy white and red flowering Rosaceæ and Amygdaleæ (Spiræa, Cratægus, Prunus spinosa, Amygdalus nana), present a pleasing appearance. I have elsewhere spoken of the tall and luxuriant Synanthereæ (Saussurea amara, S. salsa, Artemisiæ, and Centaureæ), and of leguminous plants, (species of the Astragalus, Cytisus and Caragana). Crown Imperials (Fritillaria ruthenica and F. meleagroides), Cypripediæ and tulips gladden the eye with their varied and bright hues.
A contrast is presented to this charming vegetation of the Asiatic plains by the dreary Salt Steppes, especially by that portion of the Barabinski Steppe which lies at the base of the Altai Mountains, between Barnaul and the Serpent Mountain, and by the country to the east of the Caspian. Here the social Chenopodiæ, species of Salsola, Atriplex, Salicorniæ, and Halimocnemis crassifolia[[DU]], cover the clayey soil with patches of verdure. Among the five hundred phanerogamic species which Claus and Göbel collected on the Steppes, Synanthereæ, Chenopodiæ, and Cruciferæ were more numerous than the grasses; the latter constituting only ¹⁄₁₁th of the whole, and the two former ⅐th and ⅑th. In Germany, owing to the alternation of hills and plains, the Glumaceæ (comprising the Gramineæ, Cyperaceæ, and Juncaceæ) constitute ⅐th, the Synanthereæ (Compositæ) ⅛th, and the Cruciferæ ¹⁄₁₈th of all the German Phanerogamic species. In the most northern part of the flat land of Siberia, the extreme limit of tree and shrub vegetation (Coniferæ and Amentaceæ) is, according to Admiral Wrangell’s fine map, 67° 15′ north lat., in the districts contiguous to Behring’s Straits, while more to the west, towards the banks of the Lena, it is 71°, which is the parallel of the North Cape of Lapland. The plains bordering on the Polar Sea are the domain of Cryptogamic plants. They are called Tundra (Tuntur in Finnish), and are vast swampy districts, covered partly with a thick mantle of Sphagnum palustre and other Liverworts, and partly with a dry snowy-white carpet of Cenomyce rangiferina (Reindeer-moss), Stereocaulon paschale, and other lichens. “These Tundra,” says Admiral Wrangell, in his perilous expedition to the Islands of New Siberia, so rich in fossil wood, “accompanied me to the extremest Arctic coast. Their soil is composed of earth that has been frozen for thousands of years. In the dreary uniformity of the landscape, and surrounded by reindeer, the eye of the traveller rests with pleasure on the smallest patch of green turf that shows itself on a moist spot.”