A few days’ sail brought us into the “Gulf stream,” the influence of which is felt as high as the 43 deg. north latitude.  We saw a considerable quantity of fucus natans, or gulf weed, but it generally was so far from the vessel, that I could not contrive to procure a sprig.  Mr. Luccock, in his Notes on Brazil, says, that “if a nodule of this weed, taken fresh from the water at night, is hung up in a small cabin, it emits phosphorescent light enough to render objects visible.”  He describes the leaves of this plant as springing from the joints of the branches, oblong, indented at the edges, about an inch and a half long, and a quarter of an inch broad.  Humboldt’s description is somewhat different:  he calls it the “vine-leaved fucus;” says, “the leaves are circular, of a tender green, and indented at the edges, stem brown, and three inches long.”—­What I saw of this weed rather agrees with that described by Humboldt—­the leaves were shaped like the vine leaf, and of a rusty-green colour.  That portion of the Atlantic between the 22d and 34th parallels of latitude, and 26th and 58th meridians of longitude, is generally covered with fuci, and is termed by the Portuguese, mar do sargasso, or grassy sea.  It was supposed by many, from the large quantities of this weed seen in the Gulf stream, that it grew on the Florida rocks, and by the influence and extension of the current, was detached and carried into this part of the Atlantic.  However, this position is not tenable, as a single branch of fucus has never been found on the Florida reef.  Humboldt, and other scientific men, are of opinion that this weed vegetates at the bottom of the ocean—­that being detached from its root, it rises to the surface; and that such portion of it as is found in the stream, is drawn thither by the sweeping of the current along the edge of the weedy sea.  Moreover, the fuci that are found in the northern extremity of the Florida stream are generally decayed, while those which are seen in the southern extremity appear quite fresh—­this difference would not exist if they emanated from the Gulf.

We stood to the north of the Azores, with rather unfavourable winds, and at length came between the coast of Africa and Cape St. Vincent.  Here we had a dead calm for four entire days.  The sky was perfectly cloudless, and the surface of the ocean was like oil.  Not being able to do better, we got out the boat and went turtle fishing, or rather catching, in company with a very fine shark, which thought proper to attend us during our excursion.  In such weather the turtles come to the surface of the water to sleep and enjoy the solar heat, and if you can approach without waking them, they fall an easy prey, being rendered incapable of resistance by their shelly armour.  We took six.  Attached to the breast of one was a remora, or “sucking fish.”  The length of this animal is from six to eight inches—­colour blackish—­body, scaleless and oily—­head