eastern, in a north-eastwardly direction, and that, as they approach the shores of this ocean on the east, they again turn down for lower latitudes and warmer climates. This feature in them indicates, more surely than any direct observations upon the currents can do, the presence, along the African shores in the North Atlantic, of a large volume of cooler waters. These are the waters which, having been first heated up in the caldron (§ 726) of St. Roque, in the Caribbean Sea, and Gulf of Mexico, have been made to run to the north, charged with heat and electricity to temper and regulate climates there. Having performed their offices, they have cooled down; but, obedient still to the "Mighty Voice" which the winds and the waves obey, they now return by this channel along the African shore to be again replenished with warmth, and to keep up the system of beneficent and wholesome circulation designed for the ocean.
CHAPTER XVIII.
§ 740-772. TIDE-RIPS AND THE SEA DRIFT.
740. The glories of the sea, and the destiny of the nautilus.—We never tire of the sea; like the atmosphere, it is a laboratory; in which wonders by processes the most exquisite are continually going on. Its flora and its fauna, its weaves and its tides, its currents and its salts, all in themselves afford profitable subjects of study and charming themes for thought. But as interesting as they are individually, and as marvellous too, they are not half so marvellous, nor nearly so wonderful as the offices which, with their aid, the sea performs in the physical economy of our planet. In this aspect the sea, with its insects, its salts, and its vapours, is a machine of the most beautiful construction. Its powers are vast, multitudinous, and varied. It is so stable and true in its work that nothing can throw it out of gearing, and yet its compensations are so delicate that the task of preserving them is assigned to the tiniest of its inhabitants, and to agents apparently the most subtle and fickle. They preserve its harmonies and make its adjustments, in beauty and sublimity of effect, to vie with the glories of the heavens. Take the tiny little nautilus, one of the oldest families in the sea, for example. Where, inquires M. Lucien Dubois, do they go in such fleets with their purple
