From the south-west comes a long and heavy swell; a strong breeze is blowing from the east, and threatening clouds spring upwards from the north.

These omens have a meaning.

Down to the southward, somewhere off Cape Horn, there blows a furious gale.

The wind will draw round shortly to the northward.

That is the interpretation and the reading.
A swell like this one can only witness off the Cape of Good Hope.