GENEVA, LAKE OF, the largest lake in central Europe. It is Lacus Lemannus of classical writers, but from the 16th century onwards Lac de Geneve, though from the end of the 18th century the name Lac Leman was revived. Its area is 223 sq.m., of which about 140 sq.m. are Swiss and 83 sq.m. French. The French part takes in nearly the whole of the south shore, save its west and east ends, which belong respectively to Geneva and to Valais.
The lake is formed by the Rhone, which enters it at its east end, between Villeneuve and St. Gingolph and quits it at its west end, flowing through the city of Geneva. The only important tributaries are the Drance (S.), the Venoge (N.) and the Veveyse (N.) . The direct length from Chillon to Geneva is 392 m., the maximum depth is ft., mean depth Soo ft., greatest width (between Morges and Amphion) 8; m., normal width 5 miles. The lake forms two well-marked divisions separated by the strait of Promenthoux, and as a bar, divides the Grand Lac from the Petit Lac. The "Grand Lac" is to the east and the "Petit Lac" (W.) is the special Genevese portion. The unusual blueness of the waters has long been remarked, and transparency increases away from the Rhone entry as the river-borne mud sinks to the bottom. The lake level is highest in summer. There are remark able temporary disturbances of level known as seiches both longi tudinal and transverse, in which the whole mass of water in the lake rhythmically swings from shore to shore. The currents are irregular. The principal winds that blow over the lake are the bise (north-east), the vaudaire or Fohn (south-east), the sudois or vent de pluie (south-west) and the joran (north-west). The storm winds are molan (from the Arve valley) and the bornan (from the Drance valley). The lake is not as rich in fish as the other Swiss lakes. Prof. Forel knows of but 20 indigenous species (of which the Fera, or Coregonus f era, is the principal) and six that have been introduced by man in the 19th century. Lake dwellings, of varying dates, have been found on the shores.
Despite steamers first placed on the lake in 1823, and railways along each shore, the red lateen sails of minor craft still brighten the landscape. The railway along the northern shore runs from Geneva past Nyon, Rolle, Morges, Ouchy (the port of Lausanne), Vevey and Montreux to Villeneuve (562 miles). That on the south shore gains the edge of the lake at Thonon only (22-1- m. from Geneva), and then runs past Evian and St. Gingolph to Le Bouveret (2o m. from Thonon). In the harbour of Geneva two erratic granite boulders project above the water, and are named Pierres du Niton (supposed to be altars of Neptune). The lower of the two has been taken as the basis of the triangulation of Switzerland.