Yool stood
there.

"Well, if that is not land, I do not know what is!" I replied. But
still Ben only laughed at me. I was arguing the point, when the
captain, who was on deck, called me aft. I found him with a chart,
which he was showing to Gerard.

"You are not the first person, Harry, who has taken that collection of
sea-weed for land," he observed. "That is the Sargasso Sea. When the
companions of Columbus sighted it, they thought that it marked the
extreme limits of the navigable ocean. We are at the southern edge of
it. Look at this chart; it extends in a triangular form between the
groups of the Azores, Canaries, and Cape de Verds. It is caused by the
Gulf Stream, which, circling round the Atlantic, sends off towards the
centre all the sea-weed and drift-wood collected in its course. Throw
some chips into that tub; now, set the water in motion with your hand.
The current you have created sends off all the chips into the centre of
the tub. You need never forget how this Sargasso Sea becomes covered
with weed. But you will wish to know something about this wonderful
Gulf Stream, which not only produces the effect I have described, but
exerts a very powerful influence, on the climate of many countries, and
on the navigation of the Atlantic, besides causing many other important
results. It is, indeed, one of the most wonderful of all the phenomena
of the ocean. Consider it as a mighty river of warm water flowing for
three thousand miles with scarcely diminished volume, never dying, never
overflowing, over a bottom and between banks of cold water. So little
affinity have its waters with the common water of the ocean, and so
different is their colour, that a distinct line can often be traced
where they pass along. See where it takes its rise in the Gulf of
Mexico, whence it is called the Gulf Stream. Now, mark its course, and
note its effects. Remember, that not only is it warm itself, but it
warms the air which passes over it. It likewise contains much more salt
than the common sea-water. The salt gives it its peculiar deep
indigo-like colour. It runs at the rate of between three and five miles
an hour. It is roof-shaped--that is, higher in the centre than on
either side. This is proved by placing a boat on either side of the
centre, when it drifts off towards the edge nearest to which it is cast
loose. Another peculiarity exists in connection with it. Water
radiates heat far more slowly than