20 
STRENGTH OF THE CURRENTS. 
on this direction, and in this parallel the waters, of which 
we have followed the course frnn the coasts of Honduras to 
those of Africa, mingle with the great current of the tropics 
to resume then- tour from cast to west. Several hundred 
•eagues westward of the Canary Islands, the motion pecu- 
liar to the equinoctial waters is felt in the temperate zone 
from the 28th and 29th degrees of north latitude; but on 
the meridian of tho island of Ferro, vessels sail southward 
«is iar as the tropic ol Cancer, before they find themselves 
by their reckoning, eastward of their right course.* 
We have just seen that between the parallels of 11 and 
43 degrees, the waters of the Atlantic arc driven by the 
currents in a continual whirlpool. Supposing that a mole- 
cule of water returns to tho same place from which it de- 
parted, we can estimate, from our present knowledge of the 
swiftness of currents, than this circuit of 3S00 leamies is 
not terminated in less than two years and ten months. V 
boat, which may he supposed to receive no impulsion from 
the winds, would require thirteen months to go from the 
tanary Islands to the coast of Caracas, ten months to make 
the tour of tho gulf of Mexico and reach Tortoise Shoals 
opposite the port of the Tlavannah, while forty or fifty davs 
might be sufficient to carry it from the straits of Florida to 
the bank ov Newfoundland. It would be difficult to fix the 
rapidity of the retrograde current from this bank to the 
shores of Africa; estimating the mean velocity of the waters 
at seven or eight miles in twenty-four hours, we may allow 
ten or eleven months for this last distance. Such are the 
effects of the slow but regular motion which agitates the 
waters of the Atlantic. Those of the river Amazon take 
Para lorty ' fivC dilyB to flow lVom Tomependa to Grand 
A short time before my arrival at Teneriffe, the sea had 
left m the road of Santa Cruz the trunk of a cedrela odo- 
rata covered with the bark. This American tree vegetates 
within the tropics, or in the neighbouring regions. If 
had no doubt been torn up ou the coast, of the continent, or 
of that of Honduras. The nature of tho wood, and the 
lichens which covered its bark, bore evidence that this 
trun K had not belonged to these submarine forests which 
* Sec HamboltlTs Cosmos, vol.-i., p. 312. Bohn’e edition. 
