who wishes to take advantage of them, or to
avoid them altogether, is no longer in any doubt
as to when and where they may be found.

The inhabitants of the sea-shore in tropical
countries wait every morning with impatience
the coming of the sea breeze. It usually sets
in about ten o'clock. Then the sultry heat of
the oppressive morning is dissipated, and there
is a delightful freshness in the air which seems
to give new life to all for their daily labours.
About sunset there is again another calm. The
sea breeze is now done, and in a short time the
land breeze sets in. This alternation of the
land and sea breeze—a wind from the sea by
day and from the land—by night is so regular
in intertropical countries, that they are looked
for by the people with as much confidence as
the rising and setting of the sun.

In extra-tropical countries, this phenomenon
is presented only in summer and fall. In the
summer of the southern hemisphere, the sea
breeze is more powerfully developed at
Valparaiso than at any other place known to Captain
Maury. Here, regularly in the afternoon, at
this season, the sea breeze blows furiously;
pebbles are torn up from the walks and whirled
about the streets; people seek shelter; the
Almendral is deserted, business interrupted,
and all communication from the shipping to the
shore is cut off. Suddenly the winds and the
sea, as if they had again heard the voice of
rebuke, are hushed, and there is a great calm.
The lull that follows is delightful. The sky
is without a cloud; the atmosphere is
transparency itself; the Andes seem to draw near;
the climate, always mild and soft, becomes now
doubly sweet by the contrast. The evening
invites abroad, and the population sally forth—
the ladies in ball costume, for now there is not
wind enough to disarrange the lightest curl.
In the southern summer, this change takes place
day after day with the utmost regularity; and
yet the calm always seems to surprise, and to
come before one has time to realise that the
furious sea wind could so soon be hushed.

The cause of land and sea breezes is obvious.
When a fire is kindled on the hearth, we may,
if we will observe the motes floating in the
room, see that those nearest to the chimney are
tlie first to feel the draught and to obey it—
they are drawn into the blaze. The circle of
inflowing air is gradually enlarged, until it is
scarcely perceived in the remote parts of the
room. Now the land is the hearth; the rays
of the sun, the fire; and the sea, with its cool
and calm air, the room: we have thus at our
firesides the sea breeze in miniature. When
the sun goes down, the fire ceases; then the
dry land commences to give off its surplus heat
by radiation, so that by dew-fall it and the air
above it are cooled below the sea temperature.
The atmosphere on the land thus becomes
heavier than on the sea, and consequently there
is a wind seaward which we call the land
breeze.

One of the causes which make the west coast
of Africa so very unhealthy, when compared
with places in corresponding latitudes on the
opposite side of the Atlantic, as in Brazil, is no
doubt owing to the difference of the land and
sea breezes on the two sides. On the coast of
Africa, the land breeze is universally scorching
hot. There, the land breeze is the trade wind.
It has traversed the continent, sucking up by
the way disease and pestilence from the dank
places of the interior. Reeking with miasm, it
reaches the coast. Peru is also within the
trade wind region, and the winds reach the west
coast of South America, as they do the west
coast of Africa, by an overland path; but, in the
former case, instead of sweeping over dank
places, they come cool and fresh from the pure
snows of the Andes. Between this range and
the coast, instead of marshes and a jungle, there
is a desert, a rainless country, upon which the
rays of the sun play with sufficient force not
only to counteract the trade wind power, but
to turn the scale and draw the air back from
the sea, and so cause the sea breeze to blow
regularly.

Amongst Captain Maury's most brilliant
passages are those which explain the importance of
the salts of the sea. The brine of the ocean is
the ley of the earth. From it the sea derives
dynamical power and its currents their main
strength. Hence, to understand the dynamics of
the ocean, it is necessary to study the effects of
their saltness upon the equilibrium of its waters.
Why was the sea made salt? It is the salts of
the sea that impart to its waters its curious
anomalies in the laws of freezing and of thermal
dilatation. It is the salts of the sea that assist
the rays of heat to penetrate its bosom; the
power of salt water to transmit heat is very
much greater than that of fresh. Were the sea
fresh and not salt, Ireland would never have
presented those ever-green shores which have
won for her the name of the Emerald Isle, and
the climate of England would have vied with
Labrador for inhospitality. Had not the sea
been salt, the torrid zone would have been
hotter and the frigid zone colder, for lack of
aqueous circulation; had the sea not been salt,
intertropical seas would have been at a constant
temperature higher than blood heat, and the
polar oceans would have been sealed up in
everlasting fetters of ice, while certain parts of the
earth would have been deluged with rain. Had
the seas been of fresh water, the amount of
evaporation, the quantity of rain, the volume
and size of our rivers, would all have been
different from what they are; thunderstorms
would be feeble contrivances, flashing only with
such sparks as the vegetable kingdom might
lend to the clouds, when the juices of its plants
are converted into vapour. It may seem strange
that the sheet-lightning of the clouds and the
forked flashes of the storm should have their
genesis chiefly in the salts of the sea; but true
it is that were there no salts in the waters
of the ocean, the sound of thunder would
scarcely be heard in the sky, there would he
no Gulf Stream, and no open sea within the
Arctic circle.