VOLTA  , the largest

river of the coast of Upper Guinea, between the Gambia and the Niger, with a length of about goo m . Its mouth and the greater part of its course are in British territory . Its lower course had been known since the discoveries of the Portuguese, from whom it received (15th century) its name on account of the winding nature of its stream . It was not, however, until the last fifteen years of the loth century that the extent of its basin—extending far north within the bend of the Niger- -was made known . There are two main upper branches, the Black and the White Volta . Their sources lie on the grassy plateaus north of the forest belt of the Guinea coast, the Black Volta rising (as the Baule) in about 11° N . 4° 5o' W . Its course is at first E. and N.E., to 12° 25' N., at which point, after receiving a tributary from nearly 14° N.—the most northerly point of the basin,—it turns sharply south . From the eleventh to the ninth parallel the river forms the boundary between the Northern Territories of the Gold Coast (British) and the French Ivory Coast colony . The southerly course of the stream ceases at 8° 15' N. where it is deflected E., and even N., by a mountain range composed of sandstone and granite, which it finally breaks through by a narrow pass, in which its width is only some 6o yds . Elsewhere it has a general width of 15o to 20o yds . In o° 50' W. it receives the White Volta, which flows generally south from about 13° N. and likewise breaks through a narrow gap in the plateau escarpment .

Both

rivers shrink greatly in the dry season, reaching their lowest level at the end of January . Below the junction the Volta flows S.E. and S., turning, however, E. for 4o m. just north of 6° . In 7° 37' N. it receives on the left bank a large tributary, the Oti, coming from 12° N . In its lower course, through the forest belt, the river has often a width of over half a mile, with a depth in places of .lo to 5o ft. in the rains, but in 6° 18' N. it traverses a pass in which its width is narrowed to 3o yds . Its use as a water-way is limited by a number of rapids, the lowest of which occur in 6° 7' N., above the trading port of Akuse . Its mouth is also obstructed during the greater part of the year by a bar . The river is usually navigable by small vessels from its mouth for about 6o m . The lower Volta was explored by M . J . Bonnat in 1875, but the upper basin was first traversed by the German traveller G . A . Krause (1886–87) and the French captain L .

G . Binger (1888) . It has since been explored by a number of colonial officials—German, French and British . Between 6° 41' and 8° 8' N. the Volta forms the boundary between the Gold Coast and

Togoland .