Numbers of water-courses do not reappear on the surface of the soil after being swallowed up in the earth, but flow straight to the sea by means of subterranean channels. On nearly the whole extent of the continental shores, and principally in localities where the coasts are of a calcareous nature, the outlets of submarine tributaries may be noticed, some of which are perfect rivers. Most of the springs of the department of Bouches du Rhone jet up from the bottom of the sea, but at various distances from the shore. One of them, that of Porte Miou, near Cassis, forms on the surface of the sea a considerable current, which drifts any floating bodies to a great distance. At Saint Nazaire, Ciotat, Cannes, San Remo, and Spezzia, other streams also issue from the midst of the salt waves, and attempts have even been made to measure approximately their discharge. M. Villeneuve-Flayosc estimates at 24 cubic yards a second the quantity of water discharged into the sea by all the hidden affluents of the Mediterranean between Nice and Genoa. Some of the submarine springs of Provence and Liguria proceed from enormous depths. The orifice of the spring of Cannes is 531 feet below the level of the sea; that of San Remo rises from a depth of 954 feet; lastly, at four miles to the south of Cape Saint Martin, between Monaco and Mentone, another stream of fresh water empties itself under a bed of salt water, near 2,296 feet deep. The coasts of Algeria, Istria, Dalmatia, and the Herzegovina also present numerous instances of submarine streams; on the eastern shores of the Adriatic the traveler may even have the pleasure of contemplating the delta of a considerable river, the Trebintchitza, visible through the sea-water at the depth of a yard. The abundant springs of fresh water which pour out into the open sea to the southwest of the Cuban port of Batabano are well known, since Humboldt described them, and it is observed that the lamantins, or sea-cows, which dread salt water, delight in frequenting these parts. Lastly, the Red Sea, which does not throughout its immense circumference receive a single permanent stream flowing on the surface of the ground, nevertheless receives some which spring from the bottom of its bed. The shores of the United States, the calcareous soil of which is probably pierced with caverns from the very centre of the continent, perhaps are the coasts which pour into the sea the most abundant subterranean rivers. Near the mouth of the stream of St. John, a submarine stream of perfectly pure water spouts in bubbles as far as one to two yards above the level of the sea. Off the Carolinas, and Florida, salt water has been known to change into brackish water under the influence of the sudden increase of its subterranean affluents. In the month of January, 1857, all that part of the sea which is adjacent to the southern point of Florida was the scene of an immense eruption of fresh water. Muddy and yellowish