BIENNE, LAKE OF, or Bielersee, a lake in Switzerland, S.W. of the town of Bienne, and extending along the southern foot of the Jura range. It is 712 m. in length, 212 m. broad and 249 ft. in depth, while its surface is 1424 ft. above the sea-level, and its area 16 sq. m. In it is the Île de St Pierre, where Rousseau resided for a short time in 1765. Many traces of lake-dwellings have been discovered on the shores of the lake. It receives the river Suze or Scheuss at its north-east end, while the Hagneck canal leads the waters of the Aar into the lake, as that of Nidau conducts them out again. At the southwestern end the river Thièle or Zihl flows into this lake from that of Neuchâtel. (W. A. B. C.)