Geneva, Lake Of

The lake is formed by the Rhone, which enters it at its east end, between Villeneuve (E.) and St Gingolph (W.), 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 form of the lake is that of a crescent, of which the east end is broad and rounded, while the west end tapers towards the city of Geneva. The bird’s eye length of the whole lake, from Chillon to Geneva, is 39½ m., but along its axis 45 m. The coast-line of the north shore is 59 m. in length and that of the south shore 44¾ m. The maximum depth is 1015½ ft., but the mean depth only 500 ft. The surface is 1231¼ ft. (Swiss Topog. Bureau) or 1220 ft. (Forel) above sea-level. The greatest width (between Morges and Amphion) is 8½ m., but the normal width is 5 m. The lake forms two well-marked divisions, separated by the strait of Promenthoux, which is 216½ ft. in depth, as a bar divides the Grand Lac from the Petit Lac. The Grand Lac includes the greater portion of the lake, the Petit Lac (to the west of the strait or bar) being the special Genevese portion of the lake, and having an area of but 30½ sq. m. The unusual blueness of the waters has long been remarked, and the transparency increases the farther we get from the point where the Rhone enters it, the deposits which the river brings down from the Alps gradually sinking to the bottom of the lake. At Geneva we recall Byron’s phrase, “the blue rushing of the arrowy Rhone” (Childe Harold, canto iii. stanza 71). The limit of visibility of a white disk is 33 ft. in winter (in February 1891 Prof. Forel observed an extreme of 70½ ft.) and 21¼ ft. in summer. Apart from the seasonal changes in the level of the lake (which is highest in summer, no doubt because of the melting of the Alpine snows that feed the Rhone), there are also the remarkable temporary disturbances of level known as the seiches, in which the whole mass of water in the lake rhythmically swings from shore to shore. According to Prof. Forel there are both longitudinal and transverse seiches. The effect of the longitudinal seiches at Geneva is four times as great as at Chillon, at the other end of the lake, while the extreme duration of this phenomenon is 73 minutes for the uninodal longitudinal seiches (35½ minutes for the binodal) and 10 minutes for the transverse seiches (5 minutes for the binodal). The maximum height of a recorded seiche at Geneva is rather over 6 ft. (October 1841). The currents in the water itself are irregular. The principal winds that blow over the lake are the bise (from the N.E.), the vaudaire or Föhn (from the S.E.), the sudois or vent de pluie (from the S.W.) and the joran (from the N.W.). The storm winds are the molan (from the Arve valley towards Geneva) and the bornan (from the Drance valley towards the central portion of the lake). The lake is not as rich in fish as the other Swiss lakes, one reason being the obstacle opposed by the Perte du Rhône to fish seeking to ascend that river. Prof. Forel knows of but twenty indigenous species (of which the Féra, or Coregonus fera, is the principal) and six that have been introduced by man in the 19th century. A number of lake dwellings, of varying dates, have been found on the shores of the lake. The first steamer placed on the lake was the “Guillaume Tell,” built in 1823 at Geneva by an Englishman named Church, while in 1873 the present Compagnie générale de navigation sur le lac Léman was formed, and in 1875 constructed the first saloon steamer, the “Mont Blanc.” But despite this service and the 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 (56½ m.). That on the south shore gains the edge of the lake at Thonon only (22¼ m. from Geneva), and then runs past Evian and St Gingolph to Le Bouveret (20 m. from Thonon). In the harbour of Geneva two erratic boulders of granite project above the surface of the water, and are named Pierres du Niton (supposed to be altars to Neptune). The lower of the two, which is also the farthest from the shore, has been taken as the basis of the triangulation of Switzerland: the official height is 376.86 mètres, which in 1891 was reduced to 373.54 mètres, though 376.6 mètres is now said to be the real figure. Of course the heights given on the Swiss Government map vary with these different estimates of the point taken as basis.

For all matters relating to the lake, see Prof. F.A. Forel’s monumental work, Le Léman (3 vols. Lausanne, 1892-1904); also (with fine illustrations) G. Fatio and F. Boissonnas, Autour du lac Léman (Geneva, 1902).