Chad, Tchad, or Tsad, Lake, a lake in the Soudan, Northern Africa, with an estimated area of 10,000 sq. m. in the dry season, and four or five times that extent during the rainy months. The western half contains the real lake; the eastern is generally a complex of low islands, separated by shallow canals, and inhabited by a race of semi-amphibious Negroes. The few streams that reach the lake are all small, except the Shari, which comes from the south-east. Lake Chad, whose waters are perfectly fresh, has no regular outlet. It sometimes overflows towards a great depressed plain 300 miles to the north-east. The first Europeans to see it were Denham, Clapper-ton, and Oudney; Nachtigal explored it in 1870. The lake is surrounded by the states of Bornu, Kanem, Wadai, and Bagirmi. Wadai is a strong, independent state, with Kanem and Bagirmi as its vassal states. The line that divides the sphere of French influence from the British sphere runs from Say on the Niger to Barrua on the west shore of Chad, leaving Sokoto and Bornu in the English sphere. The treaty agreed on by England and Germany in 1893 made the line between the English sphere and the German run from the Bight of Biafra to Yola on the Benue, and thence to the SW. corner of Lake Chad, leaving the southern shore of Chad, with most of Adamawa and part of Bagirmi and the mouth of the Shari, in the German sphere as the ' Hinterland' of Cameroon. This the French hotly contested on the score of treaties made with Adamawa by Mizon. The French have of late done much exploration hereabouts, with a view of extending their influence. See the work on the travels of the unfortunate explorer Crampel by Alis, .A la Conquete du Tchad (1892); and Dybowski, La Route du Tchad (1893).