ORANGE, the longest river of South Africa, almost travers ing the continent from ocean to ocean. It rises in Basutoland, less than 200 m. from the Indian ocean, and flows west, with wide sweeps south and north, to the Atlantic. It drains, with its tribu taries, an area estimated at over 400,000 sq.m., passing through more than twelve degrees of longitude or 75o m. in a straight line from source to mouth. The valley of the river exceeds i,000 m., and the stream has a length of not less than 1,300 m. Its head streams are in the highest part of the Drakensberg range, the principal source, the Sinqu, rising, at an elevation of more than 10,000 ft., on the Mont aux Sources in 28° 48' E., 28° 5o' S.
Rising on the inner slopes of the hills these rivulets all join the Sinqu, which receives from the north several streams which rise in the Maluti Mountains. Of these the largest are the Semene and Sinqunyane (little Sinqu) and the best known the Maletsunyane, by reason of its magnificent waterfall—an unbroken leap of 63o ft. Increased by the perennial waters of these numerous torrents the Sinqu makes its way S.W. across the upland valleys between the Maluti and Drakensberg ranges. After a course of some zoo m., the Sinqu, already known as the Orange, receives the Makhaleng, or Kornet Spruit (90 m.), which rises in Machacha Mountain. The Orange here enters the great inner plateau of South Africa, which at Aliwal North, the first town of any size on the banks of the river, 8o m. below the Kornet Spruit confluence, has an eleva tion of 4,300 feet. Forty miles lower down the Orange is joined by the first of its large tributaries the Caledon (23o m.), which, rising on the western side of the Mont aux Sources, flows, first west and then south, through a broad and fertile valley. At the confluence the united stream has a width of 35o yards. Thirty miles lower down the Orange reaches, in 25° 4o' E., its southern most point-3o° 4o' S., approaching within 20 m. of the Zuurberg range. In this part of its course the river receives from the south the streams, often intermittent, which rise on the northern slopes of the Stormberg, Zuurberg and Sneeuwberg ranges. Of these the chief are the Kraal, which joins the Orange near Aliwal North, the Stormberg and the Zeekoe (Sea Cow), the last named having a length of 120 miles.
From its most southern point the Orange turns sharply N.W. for 200 m., when having reached 3' S., 36' E. it is joined by its second great affluent, the Vaal (q.v.). Here it bends south again, and with many a zigzag continues its general westerly direction, crossing the arid plains of Bechuana, Bushman and Namaqualands. Flowing between steep banks, considerably below the general level of the country, here about 3,00o ft., it receives, between the Vaal confluence and the Atlantic, a distance of more than 400 m. in a direct line, no perennial tributary but on the contrary loses a great deal of its water by evaporation. In this region, nevertheless, skeleton river systems cover the country north and south. These
usually dry sandy beds, which on many maps appear rivers of im posing length, for a few hours or days following rare but violent thunder-storms, are deep and turbulent streams.
In 28° 35' S., 20' E., are the great waterfalls of the Orange, where in cataracts, and cascades the river drops 400 ft. in 16 miles. The Aughrabies or Hundred falls, as they are called, are divided by ledges, reefs and islets, the last named often assuming fantastic shapes. Below the falls the river rushes through a rocky gorge, and openings in the cliffs to the water are rare. These openings are usually the sandy beds of dried-up or intermittent affluents, such as the Bak, Ham, Houm, Aub (or Great Fish) rivers of Great Nama qualand. Crossing the narrow coastal plain the river, with a south westerly sweep, enters the ocean by a single mouth, studded with small islands, in 28° 37' S., 16° 3o' E. A large sand bar obstructs the entrance to the river, which is not quite 1 m. wide. The river when in flood, at which time it has a depth of 4o ft., scours a channel through the bar, but the Orange is at all times inaccessi ble to sea-going vessels. Above the bar it is navigable by small vessels for 3o or 4o miles.
Captain Henry Hop first crossed the Orange in Septem ber 1761, but shortly afterwards returned. In 1777 Captain (af terwards Colonel) R. J. Gordon, a Dutch officer of Scottish extrac tion, who commanded the garrison at Cape Town, reached the river in its middle course and named it the Orange in honor of the Prince of Orange. Next year Lieut. W. Paterson, an English traveller, reached the river in its lower course, and in 1779 Pater son and Gordon journeyed along the west coast of the colony and explored the mouth of the river. F. Le Vaillant also visited the Orange near its mouth in 1784. Mission stations north of the Orange were established a few days later, and in 1813 the Rev. John Campbell, after visiting Griqualand West for the London Missionary Society, traced the Harts River, and from its junc tion with the Vaal followed the latter stream to its confluence with the Orange, journeying thence by the banks of the Orange as far as Pella, in Little Namaqualand, discovering the great falls. These falls were in 1885 visited and described by G. A. Farini, from whom they received the name of the Hundred Falls. The source of the Orange was first reached by the French Protestant mission aries T. Arbousset and F. Daumas in 1836.