"Our beneficent Maker undoubtedly formed it for the benefit of his creatures," returned the captain; "but, as I have often told you, he brings about his purposes by the laws or causes which he himself has established.  There may be several causes in operation to form this ocean-stream, though up to this moment learned men have been unable to decide what they are.  Now one theory is advanced, now another.  The shape of the Gulf Stream may have something to do with it.  It appears that it is higher than the rest of the surface, for it is more bulky. Water will always seek its level.  It has thus a tendency to flow towards the colder and lower water of the poles, feeling at the same time the effect of the diurnal motion of the globe; while the water of the poles, to supply its place, flows towards the equator, subject to the same disturbing cause.  Thus the water of the globe is set in motion.  These being hot, tropical waters, remain on the surface, and a portion of them is forced into the Gulf of Mexico.  Here, though they lose somewhat of their saltness from the fresh waters of the Mississippi and Orinoco, they gain more heat from these hot streams, and are still much Salter than the rest of the ocean.  Perhaps the impetus may be given them by the pressure of the currents from the poles.  The diurnal motion of the globe will account for the drift-wood and sea-weed being cast off on the east or left bank of the stream.  There is another cause for this.  From the stream being roof-shaped, any drift which its left portion took up would have to go up hill to get to the northward. Therefore, though trees and other produce of the West Indies are found on the shores of Europe, none are ever picked up on those of America. And this brings me to the point from which I set out--the cause of the Sargasso Sea, the centre, it may be called, of this wondrous and almost inexplicable Gulf Stream."