In obedience to the law which compels liquids to seek the same level in all connected reservoirs, a rivulet of water will never fail to dart forth as a spring as soon as it finds an outlet below the caverns in which the water is collected from which it proceeds. Likewise, if the spot where the gushing out takes place is on a much lower level than that of the feeding reservoirs situated above, the liquid jet must necessarily shoot up in a column above the surface of the ground. This is the case at Châtagna, in the department of the Jura, where a natural _jet d’eau_ springs up to a height of 10 or 12 feet. In the grotto of Male-Mort, near Saint-Etienne, in Dauphiné, the jet of water is not less than 23 to 26 feet in height. But the water of the fountains being always more or less charged with sediment, the deposit accumulates in the form of a circular hillock around the orifice, thus almost always ultimately raising it to the level of the top of the liquid column. As an instance of these rising fountains, we may mention the famous springs of Moses (_Aïn Musa_), which gush out in a charming oasis not far from the shores of the Gulf of Suez. These springs, the temperature of which varies from 70° to 84° (Fahr.), now flow from the top of several small cones of sandy and slimy débris which they have gradually thrown up above the level of the plain. They are also shaded by olive and tamarind trees. In the innumerable multitude of springs, either cold or thermal, which rise from the earth, we may observe the whole range of possible temperatures from freezing-point up to the boiling-point. A spring which flows from the side of the Hangerer, in the Oetzthal, at a height of 6,742 feet, is only 1° warmer than ice. On the Alps, the Pyrenees, and all the other chains of snow-clad mountains, near the summits small rills of water are very frequently met with, the temperature of which is scarcely higher than that of melting snow. Even at the bases of mountains, and especially those of a calcareous nature, a great number of springs are found which are much colder than the surrounding soil. This is so because, in addition to the water, the air also enters the subterranean channels and circulates in all the network of clefts and crevices, and, by incessantly gliding over the wet sides of the channels, produces a rapid evaporation of moisture, and, in consequence, refrigerates the surface of the rocks and even the stream itself. The temperature, therefore, of springs which proceed from the interior of cavernous mountains is always several degrees lower than the normal temperature of the soil. Springs which have a higher temperature than the soil are called _thermal_ springs.