The Lake of Geneva is a crescent shaped lake which covers 224 square miles of both Switzerland and France. The largest Alpine lake in Europe, Lake Geneva is known for its transparent water and for its two divisions, the Grand Lac and the Petit Lac, which are separated by the strait of Promenthoux. Notable fluctuations of the lake, or seiches, move the mass of the water rhythmically from shore to shore. Ruskin uses it in Modern Painters as an example of the effect of distance on perception of reflections on water. Elsewhere he uses it as an example in describing the apparent colour of water ( Works, 3.658).