10. Conclusions.

Geographical Results.—In the course of this lengthy statement I have set forth in their respective places the principal geographical results obtained during the last five years of my stay in Central Africa; but it will perhaps be convenient to group them in a separate paragraph.

In the first place, the great geographical problem of ancient fluvial communication between the basins of the Chad and the Nile is definitely solved; the mountainous barrier encircles the basin of the Chad from the Toummo Mountains on the north to the Djebel Marra on the south-east, passing through the massif of Tibesti, the plateau of Jef-Jef, the tablelands of Erdi and Ennedi, the hills of Zagawa, and the mountains of western Dar Four.

In the second place, the lowest altitudes of the Chad basin are found in the plains of the low-lying region situated to the north-east of Lake Chad, which we have designated as “the Lowlands of the Chad.” The lowest altitude, of 160 metres (about 520 feet), was found in the ancient lake of Kirri, at a distance of about 250 miles from Lake Chad.

It is towards this low-lying zone that all the great valleys of the hydrographic system of the Western Sahara seem to converge. It is to be presumed that, such being the conditions, the tracing of a hypsometric curve of 250 or 260 metres of altitude (that is to say, slightly superior to that of the actual Chad) would fix the limits, in the region of the Chad, the Lowlands of the Chad, and Borkou, of the ancient Central African lake zone, the existence of which is proved by the agreement of the geological, topographical, ichthyological, malacological, and other observations made in these regions in the course of the last twenty years. Are we to see in the remains of this former Caspian of the Sahara the Chelonide marshes of the geographers of the ancient world? To do so would not be altogether unreasonable if it be taken into account that, so far as I am aware, there is not to be found in the south-west of the Lybian desert any other low-lying region combining conditions so favourable to the existence of a vast zone of lake or marsh.

Again, if we bear in mind certain local traditions declaring that towards the beginning of the nineteenth century native navigators were able to go in boats from the Chad to the Lowlands of the Chad by the Bahr el Ghazal (an assertion that the present appearance of Lake Kirri, recently dried up, makes sufficiently probable), one may conclude that until the early centuries of the Christian era this low-lying and now completely waterless region of the lowlands of the Chad may have been a great zone of lakes and marshes dotted with sandy or rocky archipelagoes.

Other facts may equally be noted in corroboration of this hypothesis. Firstly, the numerous layers of shells of river molluscs and the large quantity of fish-bones to be met with there: among the latter a fragment of a skull and vertebræ examined by M. J. Pellegrin, which he thought were to be attributed to a Nile perch (Lates Niloticus, L.) of about 6 or 7 feet in length (in the Comptes Rendus de l’Académie des Sciences, tome 168, No. 19, p. 963. Séance de 12 May 1919); and the discovery of an elephant skeleton in a region where neither grass nor water is any longer to be found. Attention might also be drawn to the rock-drawings of Yarda, where hippopotami are represented among horses, camels, dogs, and ostriches; or to the numerous ruins of settled villages found all up and down, especially where the Bahr el Ghazal falls into the Djourab. Lastly, it may be mentioned that on the platform of certain rocks in Borkou may be found great cemeteries that a native chief attributes to a completely vanished race of “black Christians.” But our researches revealed to us no trace or vestige of Christian religion, perhaps because we could not devote enough time to them.

A third important result has been to reveal the geographical form of important mountain masses like Tibesti and Ennedi, hitherto shown in a very imperfect fashion on the maps of Africa, and the existence of another important massif called that of Erdi, connecting the two above mentioned. Moreover, the information we received permits us to reveal to geographers the existence in the centre of the Lybian desert of yet another mountain mass, the Djebel El Aouinat, situated about 150 miles south-east of the oasis of Koufra, and of which the altitude probably exceeds 4000 feet.

A fourth interesting result has been the precise determination of the difference of longitude Paris-Faya by direct hearing of the wireless time-signals of the Eiffel Tower. Numerous rectifications of the positions attributed to various important points have resulted, the most notable being that which throws more than 50 miles to the N.N.W. the positions attributed by Nachtigal to Bardaï, the peak of Toussidé, the valley of Zouar, etc.

A fifth important result is furnished by the discovery in northern Borkou of the Harlania Harlani, which authorizes us to affirm the Upper Silurian age of all the sandstone sedimentary formations of Tibesti, Erdi, and Ennedi.

A sixth point will also, no doubt, be remarked by geographers: from the peak of Toussidé that dominates the north-west of the Tibestian massif to the Djebel Marra overlooking the plains of south-western Dar Four, that is to say, for more than 800 miles in a straight line, numerous hypsometric determinations have been effected which modify—sometimes by several thousand feet—the altitudes of the chief summits of the mountain chain that separates the basin of the Chad from that of the Mediterranean: in Tibesti, Toussidé, 10,700 feet instead of 8200, Emi Koussi, 11,200 feet; in Ennedi, the plateau of Erdébé, 4300 feet; in Tama, the peak of Niéré, 4700 feet; in Dar Four, the peak of Dourboullé, 7200 feet, the Djebel Marra, 9800 feet instead of 6000. These figures are given merely as an indication subject to the rectifications that will follow the revision now proceeding of the summary calculations rapidly effected during my journey.

Lastly, the establishment of the geographical liaison between the Niger, the Chad, and the Nile, by a chain of astronomical positions determined with very satisfactory exactitude, constitutes a seventh result, all the more interesting in that it will permit the drawing up of four sheets of the international map of the world, thanks to the 10,000 kilometres of surveys traced by my collaborators and myself during this long expedition.

From this geographical liaison allow me to pass to another kind of liaison and say a few words on a subject I have particularly at heart, and which is the conclusion not only of this five years’ journey but also of all the journeys I have had the opportunity of making in Central Africa since the beginning of the twentieth century,—I mean the importance, I will even say the necessity, of Franco-British collaboration in the great work of African civilization.

When I first set foot on the Dark Continent, in 1896, tropical and still mysterious Africa was a subject of discussions and rivalries between French and British colonials; but at the present time twenty years of fruitful emulation have ended in a definite and final division of our various possessions, and it seems to me that henceforth Africa is destined to be the tangible pledge of the union of our two countries.

I believe that in England as in France a considerable number of thoughtful men hold that it is above all to the African continent that we must look in a very large proportion for the supply of raw material and foodstuffs that we need. The question is whether it is more to the advantage of France and England to co-operate as closely as possible in developing these vast and practically unworked regions, or whether it is preferable for them to pursue this object separately, each country limiting its means of action to its own sphere of influence.

For my part, I hold that the answer is not doubtful: our two countries should unite their resources for a loyal collaboration in this essential work, so as to assure its complete success as rapidly as possible. I know that the problem is no very simple one; but have we not solved harder ones in the course of these last years, when for both our countries the question was “to be or not to be”? And since it would appear that the great and formidable economic struggle that is beginning on the morrow of the victory is destined to be as keen, if not keener, than the military struggle, it seems to me that the hearty, loyal, and complete union of our efforts can alone assure us of success.

The Trans-Sudanese.—It is an axiom henceforth beyond argument that the utilization of the riches running to waste in Tropical Africa cannot be seriously taken in hand until an adequate system of railways is constructed. Allow me, in bringing this lecture to an end, to explain what seems to me the most rational way of conceiving the general programme of the African railways north of the equator.

In the first place, we must endow Africa with a great transcontinental line from west to east, destined to ensure rapid communication between the different French and British colonies bordering on the Sudan. I have proposed for this railway the name “Transsudanese” (Comptes Rendus of the Academy of Sciences, vol. 169, p. 418. Sitting of 1 September 1919 (Gauthier Villars, Paris)); and its main lines, roughly indicated by the natural features of Africa, and following the 13th degree of north latitude, should include the following points:—

(a) Dakar and Konakry, starting-points on the Atlantic Ocean;

(b) Ouagadougou, Sokoto, Kano, Fort Lamy, Khartoum, crossing the French Sudan, British Nigeria, the French territory of the Chad, and the Anglo-Egyptian Sudan;

(c) Port-Sudan and Djibouti, termini on the Red Sea.

Secondly, along this “Transsudanese” would be formed junctions at the most suitable points, with local branch lines from the different French and British colonies that succeed one another along the Atlantic coast from the mouth of the Senegal to that of the Congo.

Thirdly, this railway system would be connected with the Mediterranean ports—on the east by the Nile valley railway from Khartoum to Cairo; on the west by a French “Transsaharian,” starting from the great bend of the Niger and connecting with the railway systems of Tunis, Algeria, and Morocco, and at some future time with that of Europe by a tunnel under the Straits of Gibraltar, or simply by train-ferry.

Among the many reasons urgently in favour of the construction of the Transsudanese, I will confine myself to stating what seems to me the most important and perhaps the least known, the question of labour. For it is generally agreed that the opening up of Tropical Africa cannot be undertaken without the large co-operation of black labour. Now, for long years to come four-fifths of that labour will have to be supplied by the Sudanese populations, much less wild and much less indolent than the great majority of the coast populations, and consequently better fitted to lend useful aid to European enterprises. This Sudanese population, which may be estimated at some fifteen millions at the lowest count, is spread over more than a million square miles (4000 miles from west to east from the Atlantic to the Red Sea, and 250 to 300 miles from north to south, between the 11th and the 15th degrees of north latitude).

To recruit workmen scattered over such vast distances and convey them without loss of time to the points where European enterprises are ready to employ them, it is evident that an unbroken line of railway must pass through the total length of the inhabited zone—that is to say, of Sudanese Africa. And it is of supreme importance that this railway should not have to take into account the political frontiers of the various colonies passed through, and that its one concern should be to traverse the regions in which the population is densest.

Such is one of the main considerations that fix the choice of the itinerary and bring me to the conclusion that the Transsudanese—a work of general interest in Africa, and more particularly a work of specially Franco-British interest—ought to be undertaken without delay, and pushed forward as actively as may be by the cordial co-operation of France and Great Britain.

These remarks do not apply to the local railways of the different colonies, though they may be expected to participate largely in the traffic of the Transsudanese, either by carrying down the products of the interior to the ports of the coast or by giving access to the regions in need of development, and in which Sudanese labour will be required. I am of opinion that these railways, limited as they are to the particular territories of the several colonies whose economic development they ensure, should continue to be constructed and managed, as hitherto, by the colonies they serve: those colonies should bear the expense of such local lines by their own financial resources, or by those placed at their disposal by the mother-country.

As for the Transsaharian, destined to connect the railways of North Africa (Morocco, Algeria, Tunis) with those of the Niger basin, I have had the opportunity of saying in another place that it has become a vital necessity of French colonial policy in Africa—a necessity that the great war has proved to demonstration. For this reason I hold that its construction should be regarded as a work of strictly national interest. Still, a glance at the map will convince the observer of the profit that will accrue to the British West African colonies, especially when it becomes possible to cross from Europe to Africa without the inconvenience of a sea-passage. I have often been met by the objection that the Transsaharian “will not pay”; that it will be almost exclusively a strategic railway, very laborious to construct, and very costly to keep in working order. Such is not my opinion. The Transsaharian, once the junction effected with the Transsudanese, will connect two exceedingly rich regions—the Africa of the Arab and Berber races and Black Africa. Between these regions a considerable commercial traffic will arise, which will have an influence as great or even greater than that of the Transsudanese itself on the economic development of Africa; its receipts per kilometre will be as large if not larger than those of the most favoured of the railways running from the colonies along the coast inland towards the Sudan, for the Transsaharian will be the direct means of penetration into the richest regions of tropical Africa, not only from North Africa, but also from the whole of Western Europe.