S T S U 277 the subject of this article has nothing in common but the name with Sosigenes the Peripatetic philosopher, author of a work on restituent spheres (2.u>ffi-y4vi]s irepl r<av dveKirrova-Siv [(r(f>aipS>i']), which is referred to by Proclus (Hypotyp., p. Ill, ed. Halma) and followed by Simplicius in his Commentary on the treatise of Aristotle, De Ceelo, author also of some other works, and master of Alexander of Aphrodisias, who lived at the end of the 2d and beginning of the 3d century after Christ, and who was the most celebrated of the commentators on Aristotle. SOTO. See DE SOTO. SOUBISE, BENJAMIN DE ROHAN, Due DE (c. 1589- 1641), was the second son of Rene 1 II., Vicomte de Rohan, and Catherine de Parthenay, and the younger brother of the soldier- writer Henri de ROHAN (q.v.). The seigneury of Soubisc came to the Rohans through Catherine, and Benjamin took the title as her second son. The exact date of his birth does not seem to be known, but it is believed to be 1589. He served his apprentice- ship as a soldier under Prince Maurice of Orange in the Low Countries. But he hardly becomes an historical character before 1621, when the religious wars once more broke out in France. He and his brother Rohan were the soul of the Huguenot party, the elder brother chiefly taking command on land and in the south, Soubise in the west and along the sea-coast. His exploits in the conflict have been sympathetically related by his brother, who, if he was not quite an impartial witness, was one of the best military critics of the time. Soubise's chief performance was a singularly bold and well-conducted attack (in 1625) on the royalist fleet in the river Blavet (which included the cutting of a boom in the face of superior numbers after a style suggestive of the best days of the English navy) and the occupation of Oleron. Soubise commanded at Rochelle during the famous siege, and if we may believe his brother the failure of the defence and of the English attack on Rlie" was mainly due to the alternate obstinacy of the townsfolk and the English commanders in refus- ing to listen to Soubise's advice. When surrender became inevitable he fled to England, which he had previously visited in quest of succour. He died in 1641, and his title afterwards served as the chief second designation (not for heirs-apparent, but for the chief collateral branch for the time being) of the house of Rohan-Chabot, into which the older Rohan honours were carried by his niece Marguerite four years after his death. SOUBISE, CHARLES DE ROHAN, PRINCE DE (1715- 1787), peer and marshal of France, grandson of the Prin- cesse de Soubise, who is known to history as one of the mistresses of Louis XIV., was born in Paris on July 15, 1715. He accompanied Louis XV. in the campaign of 1744-48, and attained high military rank, which he owed more to his courtiership than to his generalship. Soon after the beginning of the Seven Years' War, through the influence of Madame de Pompadour, he was put in com- mand of a corps of 24,000 men, and on 4th November 1757 he sustained the crushing defeat of Rossbach (see vol. ix. pp. 588-591, where also some subsequent and more favourable episodes of his military career are briefly indicated). After 1763 he lived the life of an ordinary courtier in Paris, dying on July 4, 1787. SOUDAN, or Stf DAN (Bilad es-Siidan, " Country of the Blacks "), a term applied by mediaeval Arab geographers to the region of Africa south of the Sahara mainly inhabited by peoples of Negro blood, hence corresponding to the ex- pressions Nigritia, Negroland, at one time current amongst European writers. It lies mainly between 5 and 18 N. lat., consequently entirely within the tropics, and in its widest sense stretches right across the continent from Cape Verd on the Atlantic to Massowah on the Red Sea. But the term is more usually restricted to the region bounded N. by the Sahara, S. by Upper Guinea and the lands draining to the Congo basin, W. and E. by Sene- gambia and the Abyssinian highlands respectively (see vol. i. plate II.). Within these limits it has an extreme length of about 3000 miles between the Senegal river and Abyssinia, extending southwards at some points 660 miles, with a total area of perhaps 2,000,000 square miles, and a population approximately estimated at from 80 to 90 millions. From the arid and sandy northern wastes to the well-watered and arable Soudanese lands the transi- tion is effected by an intermediate zone of level grassy steppes, partly overgrown with mimosas and acacias, with a mean breadth of about 60 miles, between 17 and 18 N. lat., but towards the centre reaching as far south as 15 N. Excluding this somewhat uniform transitional zone, the Soudan, properly so called, may be described as a moderately elevated region, diversified with extensive open or rolling plains, level plateaus, and even true high- lands, especially in the south-west. It constitutes three distinct hydrographic systems, corresponding to the three main physical divisions of Western Soudan, draining through the Niger southwards to the Atlantic ; Central Soudan, draining to the great central depression and land- locked basin of Lake Tchad; and Eastern (Egyptian) Soudan, draining through the Nile northwards to the Mediterranean. Between these systems the chief water- partings are (1) the Marrah Mountains of Dar-Fur, whence flow the Bahr es-Salamat west to the Shari, and numerous intermittent wadies east to the Nile ; (2) the Monbuttu uplands (Mount Baginze), separating the western head- streams of the White Nile from the Welle (Bahr Kuta), which, according to the latest information, flows, not to the Shari as Schweinfurth supposed, but to the Congo through the Mbangi; (3) the so-called "Kong" Moun- tains, dividing the Niger basin from the Volta and other streams flowing in independent channels south to the Gulf of Guinea. The Adamawa highlands, culminating in Mount Alantika (9000 to 10,000 feet), do not form a divide, as was supposed, between the Binue (the main eastern tributary of the Niger) and the Logon and other streams flowing east to the Shari (the great southern afflu- ent of Lake Tchad). Flegel, who has recently explored the upper course of the Binue, found that it sweeps right round the east foot of Mount Alantika, and is even navigable round this bend and some way southwards. On the other hand, the central hydrographic system of Lake Tchad has been greatly reduced in size since Lupton, Grenfell, and other recent explorers have made it evident that the Bahr- Kuta (Welle) flows not to the Shari but to the Congo basin. The Shari basin, which is now known not to reach farther south than about 6 N. lat., may even be almost considered, physically as well as politically, as subsidiary to the Niger hydrographic system, for there are indications that the Logon once flowed into the Binue by the Mayo- Kebbi. The Mayo-Kebbi is a long flat trough or valley in 9 30' N. lat., with a level swamp at the bottom receiving as a backwater the overflow of the Logon, and also draining through the Binue to the Niger. By canalizing the Mayo- Kebbi the Binue and Shari basins might be permanently connected, in which case the Niger system would afford a navigable waterway from the Gulf of Guinea to the southernmost limits of Baghirmi. From the Kong highlands, some of whose peaks appear to attain elevations of 6000 to 7000 feet, Western Soudan falls gradually towards the north and north-east down to the Great Desert, where the city of Timbuktu still main- tains an altitude of 770 feet above sea-level (Lenz). South- east of the Niger the land rises in terraces of 1000 and even 3000 feet, above which isolated crests range from 5000 to 9000 feet. This little-known western highland region, comprised between the Binue and the lower Niger,
