"And what are the trade-winds, which I heard poor Captain Osborn talking
about after we left Madeira?"

"The trade-winds blow on the equator, and several degrees north and
south of it, from the east to the west, following the course of the
sun."

"Is it the sun which produces these winds?"

"Yes, the extreme heat of the sun between the tropics rarefies the air
as the earth turns round, and the trade-winds are produced by the
rushing in of the less heated air."

"Yes, William; and the trade-winds produce what they call the Gulf
Stream," observed Ready.

"How is that? I have heard it spoken of, papa."

"The winds, constantly following the sun across the Atlantic Ocean, and
blowing from east to west, have great effect upon the sea, which is
forced up into the Gulf of Mexico (where it is stopped by the shores of
America), so that it is many feet higher in the Gulf than in the eastern
part of the Atlantic. This accumulation of water must of course find a
vent somewhere, and it does in what is called the Gulf Stream, by which
the waters are poured out, running very strong to the northward, along
the shores of America, and then [westward] eastward, passing not far
from Newfoundland, until its strength is spent somewhere to the
northward of the Azores."

"The Gulf Stream, William," said Ready, "is always several degrees
warmer than the sea in general, which is, they say, owing to its waters
remaining in the Gulf of Mexico so long, where the heat of the sun is so
great."

"What do you mean by the land and sea breezes in the West Indies, and
other hot climates, papa?"

"It is the wind first blowing off from the shore, and then blowing from
the sea towards the shore, during certain hours of the day, which it
does regularly every twenty-four hours. This is also the effect of the
heat of the sun. The sea breeze commences in the morning, and in the
afternoon it dies away, when the land breeze commences, which lasts till
midnight."

"There are latitudes close to the trade-winds," said Ready, "where the
wind is not certain, where ships have been becalmed for weeks; the crews
have exhausted the water on board, and they have suffered dreadfully.
We call them the Horse latitudes--why, I do not know. But it is time
for us to leave off, and for Master William to go into the house."

They returned home, and after supper Ready went on with his narrative.

"I left off at the time that I was sent on board of the man-of-war,