half to more than four miles per hour. It is at length turned
westward by the Lagullas bank, which rises from a sea of great depth to
within one hundred fathoms of the surface. It must therefore be
inferred, says Rennell, that the current here is more than one hundred
fathoms deep, otherwise the main body of it would pass across the bank,
instead of being deflected westward, so as to flow round the Cape of
Good Hope. From this cape it flows northward, as before stated, along
the western coast of Africa, taking the name of the South Atlantic
current. It then enters the Bight, or Bay of Benin, and is turned
westward, partly by the form of the coast there, and partly, perhaps, by
the Guinea current, which runs from the north into the same great bay.
From the centre of this bay proceeds the equatorial current already
mentioned, holding a westerly direction across the Atlantic, which it
traverses, from the coast of Guinea to that of Brazil, flowing
afterwards by the shores of Guiana to the West Indies. The breadth of
this current varies from 160 to 450 geographical miles, and its velocity
is from twenty-five to seventy-nine miles per day, the mean rate being
about thirty miles. The length of its whole course is about 4000 miles.
As it skirts the coast of Guiana, it is increased by the influx of the
waters of the Amazon and Orinoco, and by their junction acquires
accelerated velocity. After passing the island of Trinidad it expands,
and is almost lost in the Caribbean Sea; but there appears to be a
general movement of that sea towards the Mexican Gulf, which discharges
the most powerful of all currents through the Straits of Florida, where
the waters run in the northern part with a velocity of four or five
miles an hour, having a breadth of from thirty-five to fifty miles.[383]

The temperature of the Gulf of Mexico is 86 degrees F. in summer, or 6
degrees higher than that of the ocean, in the same parallel (25 degrees
N. lat.), and a large proportion of this warmth is retained, even where
the stream reaches the 43 degrees N. lat. After issuing from the Straits
of Florida, the current runs in a northerly direction to Cape Hatteras,
in North Carolina, about 35 degrees N. lat., where it is more than
seventy miles broad, and still moves at the rate of seventy-five miles
per day. In about the 40 degrees N. lat., it is turned more towards the
Atlantic by the extensive banks of Nantucket and St. George, which are
from 200 to 300 fe