362 PHYSICAL GEOGRAPHY. 



The other and principal branch, known by the name of the Guiana current, is properly 

 a direct continuation of the equatorial. It runs from off Cape St. Roque, across the mouth 

 of the Amazon ; and after skirting the low coast of Guiana, and passing through the 

 Caribbean Sea, it enters the Gulf of Mexico, where a course is commenced in a fresh 

 direction. Mention has previously been made of the gulf stream. This originates in 

 the Mexican Gulf, and is the efflux of the waters accumulated there by the equatorial 

 current. The stream is first clearly perceptible to the north-west of the island of Cuba, 

 where it flows weakly to the east ; but upon being turned from that direction by the 

 opposition of immense sand-banks, it proceeds northward, and, owing to the narrowness 

 of the channel, rushes with great velocity through the Strait of Florida. Obeying the 

 impulse there given to its waters, the gulf stream runs along the coast of the United 

 States ; and, being there free from obstruction, it gradually expands in volume, and dimi- 

 nishes in rapidity. On striking the banks of Newfoundland it sets again to the east, and 

 to the south-east upon joining the north polar current. It then traverses the basin of the 

 Atlantic to the Azores, enters the , equatorial current on the coast of Africa, and is con- 

 ducted again to the west, to re-enter into itself in the Gulf of Mexico. 



The equatorial current and the gulf stream thus constitute a whirlpool of prodigious 

 extent in the Atlantic Ocean, which cuts laterally the gorge between Africa and the 

 Brazils, scours round the indentation of Central America, recrosses the bed of the Atlantic 

 following an opposite direction, and is perpetually circulating in the same route. Hum- 

 boldt remarks, that supposing a particle of water returns to the same place from which it 

 departed, our present knowledge of the swiftness of currents will enable us to estimate, 

 that this circuit of 3800 leagues will require not less than two years and ten months for its 

 accomplishment. " A boat which may be supposed to receive no impression from the 

 winds, would require thirteen months from the Canary Islands to reach the coast of 

 Caraccas ; ten months to make the tour of the Gulf of Mexico, and reach Tortoise Shoals 

 opposite the port of the Havannah ; while forty or fifty days might be sufficient to carry 

 it from the Straits of Florida to the bank of Newfoundland. It would be difficult to fix 

 the rapidity of the retrograde current from this bank to the coasts of Africa: but estimating 

 the mean velocity of the waters at seven or eight miles in twenty-four hours, we find ten 

 or eleven months for this last distance. A short time," he continues, " before my arrival 

 at TenerifFe, the sea had left in the road of St. Croix a trunk of a Cedrela odorata covered 

 with the bark. This American tree vegetates exclusively under the tropics, or in the 

 neighbouring regions, and it had no doubt been torn up on the coast of the continent, or of 

 that of Honduras. The nature of the wood, and the lichens which covered its bark, were 

 evident proofs that this trunk did not belong to those submarine forests which ancient 

 revolutions of the globe have deposited in lands transported from the polar regions. If 

 the Cedrela, instead of having been thrown on the strand of TenerifFe, had been carried 

 farther south, it would probably have made the whole tour of the Atlantic, and returned 

 to its native soil with the general current of the tropics." The conjecture in the last pas- 

 sage is supported by a fact recorded in the history of the Canaries by the Abbe Viera. 

 In the year 1770 a small vessel laden with corn, and bound from the island of Lancerotte 

 to Vera Cruz in TenerifFe, was driven to sea while none of the crew were on board, and 

 was carried by the westward motion of the waters across the bed of the Atlantic, where 

 it went ashore at La Guayra, near Caraccas. It was the equatorial current that conveyed 

 the fragment of the vessel to Guadaloupe which Columbus found floating near the island ; 

 and the gulf stream brought those productions of the New World to the Canaries, upon 

 which he seized as indications of the existence of western regions, before the discovery of 

 them had been efFected. A complete view of this great water-course would require a 

 notice of several subordinate currents; but it may be sufficient to observe, that the 



