The waters of the northern part of the Atlantic between Europe, Northern Africa, and the New Continent, are agitated by a continually recurring gyratory movement. Under the tropics the general current to which the term rotation-stream might appropriately be given in consideration of the cause from which it arises, moves, as is well known, like the trade wind from east to west. It accelerates the navigation of vessels sailing from the Canary Isles to South America; while it is nearly impossible to pursue a straight course against the current from Carthagena de Indias to Cumana. This bend to the west, attributed to the trade winds, is accelerated in the Caribbean Sea by a much stronger movement, which originates in a very remote cause, discovered as early as 1560 by Sir Humphrey Gilbert,[[FE]] and confirmed in 1832 by Rennell. The Mozambique current, flowing from north to south between Madagascar and the eastern coast of Africa, sets on the Lagullas Bank, and bends to the north of it round the southern point of Africa. After advancing with much violence along the western coast of Africa beyond the equator to the island of St. Thomas, it gives a north-westerly direction to a portion of the waters of the South Atlantic, causing them to strike Cape St. Augustin, and follow the shores of Guiana beyond the mouth of the Orinoco, the Boca del Drago, and the coast of Paria.[[FF]] The New Continent from the Isthmus of Panama to the northern part of Mexico forms a dam or barrier against the movements of the sea. Owing to this obstruction the current is necessarily deflected in a northerly direction at Veragua, and made to follow the sinuosities of the coast-line from Costa Rica, Mosquitos, Campeche, and Tabasco. The waters which enter the Mexican Gulf between Cape Catoche of Yucatan, and Cape San Antonio de Cuba, force their way back into the open ocean north of the Straits of Bahama, after they have been agitated by a great rotatory movement between Vera Cruz, Tamiagna, the mouth of the Rio Bravo del Norte, and the Mississippi. Here they form a warm, rapid current, known to mariners as the Gulf Stream, which deflects in a diagonal direction further and further from the shores of North America. Ships bound for this coast from Europe, and uncertain of their geographical longitude, are enabled by this oblique direction of the current to regulate their course as soon as they reach the Gulf Stream by observations of latitude only. The bearings of this current were first accurately determined by Franklin, Williams, and Pownall.
From the parallel of 41° north lat. this stream of warm water follows an easterly direction, gradually diminishing in rapidity as it increases in breadth. It almost touches the southern edge of the Great Newfoundland Bank, where I found the greatest amount of difference between the temperature of the waters of the Gulf Stream and those exposed to the cooling action of the banks. Before the warm current reaches the Western Azores it separates into two branches, one of which turns at certain seasons of the year towards Ireland and Norway, while the other flows in the direction of the Canary Isles and the western coast of Northern Africa.
The course of this Atlantic current, which I have described more fully in the first volume of my travels in the regions of the tropics, affords an explanation of the manner in which, notwithstanding the action of the trade winds, stems of the South American and West Indian dicotyledons have been found on the coasts of the Canary Islands. I made many observations on the temperature of the Gulf Stream in the vicinity of the Newfoundland Bank. This current bears the warmer water of lower latitudes with great rapidity into more northern regions. The temperature of the stream is therefore from about 4°½ to 7° Fahr. higher than that of the contiguous and unmoved water which constitutes the shore as it were of the warm oceanic current.
The flying-fish of the equinoctial zone (Exocetus volitans), is borne by its predilection for the warmth of the water of the Gulf Stream far to the north of the temperate zone. Floating sea-weed (Fucus natans), chiefly taken up by the stream in the Mexican Gulf, makes it easy for the navigator to recognize when he has entered the Gulf Stream, whilst the position of the branches of the sea-weed indicate the direction of the current. The mainmast of the English ship of war, the Tilbury, which was destroyed by fire in the seven years’ war on the coasts of Saint Domingo, was carried by the Gulf Stream to the northern coasts of Scotland: and casks filled with palm-oil, the remains of the cargo of an English ship wrecked on a rock off Cape Lopez in Africa, were in like manner carried to Scotland, after having twice traversed the Atlantic Ocean, once from east to west between 2° and 12° north lat., following the course of the equinoctial current, and once from west to east between 45° and 55° north lat. by help of the Gulf Stream. Rennell, in the work already referred to, p. 347, relates the voyage of a bottle inclosing a written paper which had been thrown from the English ship Newcastle in 38° 52′ north lat., and 63° 58′ west long., on the 20th of January, 1819, and which was first seen on the 2nd of June, 1820, at the Rosses in the north-west of Ireland, near the Island of Arran. Shortly before my arrival at Teneriffe a stem of South American cedar-wood (Cedrela odorata), thickly covered with lichens, was cast ashore near the harbour of Santa Cruz.
The effects of the Gulf Stream in stranding on the Azorean Islands of Fayal, Flores, and Corvo, bamboos, artificially cut pieces of wood, trunks of an unknown species of pine from Mexico or the West Indies, and corpses of men of a peculiar race, having very broad faces, have mainly contributed to the discovery of America, as they confirmed Columbus in his belief of the existence of Asiatic countries and islands situated in the west. The great discoverer even heard from a settler on the Cap de la Verga in the Azores “that persons in sailing westward had met with covered barks, which were managed by men of foreign appearance, and appeared to be constructed in such a manner that they could not sink, almadias con casa movediza que nunca se hunden.” There are well authenticated proofs, however much the facts may have been called in question, that natives of America (probably Esquimaux from Greenland or Labrador), were carried by currents or streams from the north-west to our own continent. James Wallace[[FG]] relates that in the year 1682 a Greenlander in his canoe was seen on the southern extremity of the Island of Eda by many persons, who could not, however, succeed in reaching him. In 1684 a Greenland fisherman appeared near the Island of Westram. In the church at Burra there was suspended an Esquimaux boat, which had been driven on shore by currents and storms. The inhabitants of the Orkneys call the Greenlanders who have appeared amongst them Finnmen.
In Cardinal Bembo’s History of Venice I find it stated, that in the year 1508 a small boat, manned by seven persons of a foreign aspect, was captured near the English coast by a French ship. The description given of them applies perfectly to the form of the Esquimaux (homines erant septem mediocri statura, colore subobscuro, lato et patente vultu, cicatriceque una violacea signato). No one understood their language. Their clothing was made of fish skins sewn together. On their heads they wore coronam e culmo pictam, septem quasi auriculis intextam. They ate raw flesh, and drank blood as we would wine. Six of these men perished during the voyage, and the seventh, a youth, was presented to the King of France, who was then at Orleans.[[FH]]
The appearance of men called Indians on the coasts of Germany under the Othos and Frederic Barbarossa in the tenth and twelfth centuries, and as Cornelius Nepos (in his Fragments),[[FI]] Pomponius Mela,[[FJ]] and Pliny[[FK]] relate, when Quintus Metellus Celer was Proconsul in Gaul, may be explained by similar effects of oceanic currents and by the long continuance of north-westerly winds. A king of the Boii, or, as others say, of the Suevi, gave these stranded dark-coloured men to Metellus Celer. Gomara[[FL]] regards these Indian subjects of the King of the Boii as natives of Labrador. He writes, Si ya no fuesen de Tierra del Labrador, y los tuviesen los Romanos por Indianos engañados en el color. It may be inferred that the appearance of Esquimaux on the northern shores of Europe was more frequent in earlier times, for we learn from the investigations of Bask and Finn Magnusen, that this race had spread in the eleventh and twelfth century in considerable numbers, under the name of Skrälingers, from Labrador as far south as the Good Vinland, i.e. the shore of Massachussets and Connecticut.[[FM]]
As the winter cold of the most northern part of Scandinavia is ameliorated by the action of the Gulf Stream, which carries American tropical fruits (as cocoa-nuts, seeds of Mimosa scandens and Anacardium occidentale) beyond 62° north lat.; so also Iceland enjoys from time to time the genial influence of the diffusion of the warm waters of the Gulf Stream far to the northward. The sea coasts of Iceland, like those of the Faroe Isles, receive a large number of trunks of trees, driven thither from America; and this drift-wood, which formerly came in greater abundance, was used for the purposes of building, and cut into boards and laths. The fruits of tropical plants collected on the Icelandic shores, especially between Raufarhaven and Vapnafiord, show that the movement of the water is from a southerly direction.[[FN]]
[25]. p. 10.—“Lecideæ and other Lichens.”
In northern regions, the absence of plants is compensated for by the covering of Bœomyces roseus, Cenomyce rangiferinus, Lecidea muscorum, Lecidea icmadophila, and other cryptogamia which are spread over the earth, and which may be said to prepare the way for the growth of grasses and other herbaceous plants. In the tropical world, where mosses and lichens are only observed to abound in shady places, some few oily plants supply the place of the lowly lichen.