laugh of the light-hearted middies, enchanted with the uproar, make a
fine concert. The sedative effect of two or three hours of this work
exceeds fresh-water belief; so that in a day or two, Messrs. Neptune,
Boreas, First Lieutenant, and Co., have re-established their
legitimate authority so completely, that neither servants, nor any
other passengers, ever afterwards venture to indulge in those
liberties which, at first coming on board, they fancied might be taken
with impunity.




CHAPTER V.

THE TROPICAL REGIONS AT SEA.


There sailed along with us in the Volage, from Spithead, the Princess
Caroline, 74, and the Theban frigate, to aid in protecting a fleet of
East India Company's ships, all for China direct.[2] As these ships
were of the largest class, well manned, well commanded, and were
likewise pretty well armed, and got up to look like men-of war, our
force had not only an imposing appearance, but was capable of baffling
an enemy, even in considerable strength. There is, indeed, one signal
instance on record in which a fleet of East India Company's ships
actually beat off, unassisted, a French squadron of very powerful
vessels. These striking incidents, peeping out from time to time, show
what is called the true blood, and are extremely valuable, proving how
essential it is that an officer in command should "Never say die while
there is a shot in the locker!" a pithy old phrase, which will apply
to many situations in life, civil as well as military. Had the gallant
commander alluded to, Sir Nathaniel Dance, yielded when the French
Admiral Linois, and his squadron, consisting of the Marengo, a
line-of-battle ship of 84 guns, and the Belle Poule and Semillante
frigates, each of 44, bore down on the China fleet, not less than six
millions of English property, and some of the noblest trading ships
that float on the ocean, must have been carried into the Isle of
France.

This memorable affair took place near Pulo Aor, in the China seas, and
by a very interesting, and no doubt useful coincidence, on the 14th of
February, 1804, the seventh anniversary of the glorious action off
Cape St. Vincent. Had the enemy only known the real force of his
opponents, which he most certainly ought to have found out before he
quitted them, the bold front these ships put forward might indeed have
served them nothing. A less resolute man than Captain Dance might have
said this good fortune was hardly to be calculated upon; but it is the
duty of a commander, at all times and under all circumstances, to
afford himself every possible chance, and never to give up while there
is one of these chances left.

A useful chapter in naval history and tactics could be written on the
defence of convoys, by which it might perhaps be made manifest that a
determined bearing, accompanied by a certain degree of force, and a
vigorous resolution to exert that force to the utmost, would, in most
cases, save the greater part of the convoy, even against powerful
odds. In the well-known instance, in which Captain Richard Budd
Vincent sacrificed his ship, in a contest where he was from the first
sure to be overpowered, he gained sufficient time for most of his
flock of merchant-ships to escape.

In February, 1805, this gallant officer, in the Arrow, of 18
twenty-four pounders, ably supported by Captain Arthur Farquhar, in
the Acheron bomb, carrying not half that number, actually engaged two
large French frigates, mounting in all 90 guns and 1300 men, while the
English force was only 26 guns and 90 men. The damage and delay caused
to the enemy by this spirited resistance enabled the convoy to
disperse, and all get off but three, out of thirty-two. The English
ships did not strike till they were so much cut up that one sunk
immediately afterwards, and the other was burned by the captors as
useless.

On the occasion of our voyage in 1812, however, the fortitude and
skill of our East India ships were put to no such proof, as our most
interesting evolutions were confined to the interchange of good
dinners; for your Indiamen know as well how to eat, drink, and be
merry, as to fight, if need be. Their chief business is to trade; but
their trading is a widely different thing from that of the ordinary
merchant service. The East India Company's officers are bred in many
respects like naval men, and they feel in the same manner. Being
sprung from as good a stock as the officers of the Navy, they possess
a kindred gentleman-like spirit, and are in every respect suitable
allies in battle.

In fine weather, during our whole voyage, there scarcely occurred a
day on which, in the course of the morning, if the sea were tolerably
smooth, and the wind not too strong, the dinner invitation signal was
not displayed from the commodore, or from some of his flock. When
there was a breeze, and the ships were making way through the water,
some technical address was necessary to avoid delay. This will easily
be understood, without going into minute details, when it is
remembered, that there must always in a convoy be found certain ships
which sail worse than others, and that, although these tubs, as they
are most deservedly called, crowd all their canvas, the rest are
obliged to shorten sail in order to keep them company; as Lightfoot,
in the fairy tale, was obliged to tie his feet in the race. If it be
the commodore who gives the dinner, he either heaves to, while the
boats of the several captains come on board, or he edges down to the
different ships in succession, passes them at the distance of a
quarter of a cable's length, picks up his guests, and resumes his
station ahead, or to windward, or wherever it may suit him to place
himself so as best to guard his charge. If any of the fast sailers
have occasion to heave to, either before or after dinner, to lower
down or to hoist up the boat which carries the captain backwards and
forwards to the ship in which the entertainment is given, and in
consequence of this detention any way has been lost, that ship has
only to set a little more sail that she may shoot ahead, and regain
her position in the line.

The bad sailers of all fleets or convoys are daily and hourly
execrated in every note of the gamut; and it must be owned that the
detention they cause, when a fine fresh breeze is blowing, is
excessively provoking to all the rest, and mortifying to themselves.
Sometimes the progress of one haystack of a vessel is so slow that a
fast-sailing ship is directed to take her in tow, and fairly lug her
along. As this troublesome operation requires for its proper execution
no small degree of nautical knowledge, as well as dexterity, and must
be performed in the face of the whole squadron, it is always exposed
to much sharp criticism. The celerity with which sail is set, or taken
in, by the respective ships, or the skill with which broken spars are
shifted, likewise furnish such abundant scope for technical
table-talk, that there is seldom any want of topic in the convoy.
Sailors, indeed, are about as restless as the element on which they
float; and their hands are generally kept pretty full by the necessity
of studying the fluctuating circumstances of wind and weather,
together with due attention to the navigation.

These occupations served to give a high degree of interest to this
Indian voyage, which, to most of us, was the first; the mere
circumstance of having to pass successively and quickly through a
number of different climates, first in the order of increasing warmth,
and then in the reverse order of increasing cold, was of itself most
striking. The change of latitude being the chief cause of these
phenomena, a succession of astronomical variations were necessarily
attendant upon the progress of the voyage; easily explained by
reasonings, and the actual, practical exhibition, as it may be termed,
of the truths of astronomical science failed not to strike the
unfamiliarised imagination as both wonderful and beautiful.

When we sailed from England the weather was very cold, raw, and
uncomfortable; and although we had a couple of days' fair wind at
starting, we were met in the very chops of the channel by hard-hearted
southerly and south-westerly winds, which tried our patience sorely.
On the evening of the tenth day we caught a glimpse of the north coast
of Spain; and the rugged shore of Galicia was the last which most of
us saw of Europe for many years. It was not till after a fortnight's
hard struggling against these tiresome south-westers that we anchored
in Funchal Roads, having by the way dropped several of our convoy.
These stray sheep came in during the few days we remained to refresh
ourselves at this most charming of resting-places. After nearly a
week's enjoyment, we proceeded on our course to the southward; within
three days we came in sight of Palma, the most northern of the Canary
Island group. It was thirty miles distant in the south-east quarter;
and Teneriffe, the sea "monarch of mountains," lay too far off for us
to perceive even his "diadem of snow," which at that season (April), I
presume, he always wears. Some years after the period in question,
when I paid him a visit, in the month of August, the very tip-top was
bare, and the thermometer at 70 deg..

Under more favourable circumstances, we might possibly have seen
Teneriffe from the Volage, for our distance was not above a hundred
miles. This, however, it must be owned, is a long way to see the land,
unless it form a continuous ridge of great elevation, like the Andes;
and even then, to be distinguished well, it requires to be interposed
between a bright sky and the ship. At day-break, and for about half an
hour before sunrise, if the weather be clear, even sharp peaks, like
the cone of Teneriffe, may be seen with a degree of distinctness which
is very remarkable, when viewed from the distance of a hundred miles
and upwards, as I have several times experienced when navigating in
the Pacific. But when the full splendour of the sun's light begins to
fill the air, these gigantic forms gradually fade away amongst the
clouds, or melt into the sky, even when no clouds are visible. I have
likewise been told, that, in sailing directly away from Teneriffe (or
other high insulated peaks), and keeping the eye pretty constantly
fixed in the proper direction, it may be retained in sight at much
greater distance than it can be discovered on approaching. I am
disposed to consider this very probable, but have never had a good
opportunity of trying the experiment.

It was late in April, as we were stealing slowly past these distant
Canary Islands, when the first real puff of the Trade-wind caught our
sleeping sails, and made the braces, haulyards, and all the other
ropes connected with the yards, crack again. This breeze served more
effectually to detach our thoughts from European interests than
anything which had occurred since our leaving England. At the very
moment, however, when we were chuckling at this disentanglement of our
feelings from domestic anxieties, and all the varied agitation of home
concerns, we observed a ship crossing our path at some distance.
Signal being made to chase, we instantly darted off from the convoy to
examine the stranger, which proved to be an English ship from Lisbon.
We hailed, and asked, "What news?"

"Badajoz has fallen," replied the other, "after a terrible siege."

This was received with a general buzz of joyous congratulation along
the decks. In answer to further questions, we were told of some three
or four thousand men killed and wounded in the trenches and breach.
Then, indeed, the glorious intelligence was greeted by three jolly
huzzas from every ship in the convoy!

Nothing so startling as this occurred to us again; but the serenity of
our thoughts was in some degree interrupted, a few days afterwards, by
the north-easterly Trade-wind dying away, and a gentle south-wester
springing up in its place. This occurred in latitude 25-1/2 deg. N.,
where, according to our inexperienced conception of these singular
winds, we ought to have found a regular breeze from the very opposite
quarter! Nor was it till long afterwards that I learned how much the
force and direction of the Trade-winds are liable to modification by
the particular position which the sun occupies in the heavens; or how
far the rotatory motion of the earth, combined with the power which
the sun possesses of heating certain portions of the circumambient
air, are the regulating causes of the Trades, Monsoons, and, indeed,
of all the other winds by which we are driven about. It is by no means
an easy problem in meteorology to show how these causes act in every
case; and perhaps it is one which will never be so fully solved as to
admit of very popular enunciation applicable to all climates. In the
most important and useful class of these aerial currents, called, _par
excellence_, and with so much picturesque truth, "the Trade-winds,"
the explanation is not difficult. But before entering on this curious
and copious theme, I feel anxious to carry our convoy fairly across
the tropical regions; after which an account of the Trades will be
better understood.

I have just mentioned that the changes of temperature, on a voyage to
India, are most remarkable. We set sail, for instance, in the month
of March, when it was bitterly cold in England; then we came off the
coast of Spain, where it was a little more moderate; next to Madeira,
which is always agreeable. Then we passed the Canaries; after which we
sailed over the tropic of Cancer, and got well toasted in the torrid
zone; steered down upon the equinoctial line, passed the tropic of
Capricorn, and again became conscious of the weakened influence of the
sun; till, at length, off the Cape of Good Hope, we were once more
nipped with the cold. Anon, having rounded the south point of Africa,
we put our heads towards the line, and a second time, within a few
weeks, emerged from the depth of winter into the height of summer.

The proximate cause of all these vicissitudes was, of course, our
approach towards and removal from the direct influence of the great
source of light and heat. At one time, the sun, even at noon, was seen
creeping stealthily along, low down in the horizon, at another his
jolly countenance was blazing away right overhead. On the 5th of May,
when our latitude was 17-1/2 deg. N., the sun's declination was 16-1/4 deg.
N., his centre being only one degree from our zenith: shadows we had
none. On that day we saw St. Antonio, the north-westernmost of the
Cape de Verde Islands, the summit of which is about seven thousand
feet above the sea.

On the next day I well remember going on deck with a certain flutter
of spirits, to see, for the first time in my life, the sun to the
northward, and moving through the heavens from right to left, instead
of from left to right. No one doubts that the earth is round; yet
these conspicuous and actual proofs of its rotundity always amuse the
fancy, and frequently interest the judgment, almost as much as if they
were unexpected. The gradual rise, night after night, of new stars and
new constellations, belongs to a still higher order of curiosity; for
it not merely places well-known objects in strange positions, but
brings totally new subjects of contemplation before our eyes, and
leads us to feel, perhaps more strongly than upon any other occasion,
the full gratification which novelty on the grandest scale is capable
of producing. I shall never forget the impatience with which I have
often watched the approach of darkness after a long day's run to the
south, knowing that, in a few moments, I was to discover celestial
phenomena heretofore concealed from my view.

After slanting through the north-east Trade-wind, we reached that
well-known but troublesome stage in the voyage, so difficult to get
over, called the Variables. This region has acquired its title from
the regular Trades not being found there, but in their place unsteady
breezes, long calms, heavy squalls, and sometimes smart winds from the
south and south-westward. These Variables, which sorely perplex all
mariners, even those of most experience, while they drive young ones
almost out of their senses, are not less under the dominion of the
causes which regulate those great perennial breezes the Trades,
blowing to the northward and southward of them. Their laws, however,
are not quite so readily understood, and consequently are not so
easily allowed for in the practice of navigation.

When we actually encounter, on the spot, and for the first time, a
crowd of new circumstances, of which, previously, we have only known
the names, or have merely heard them described by others, we feel so
much confused and bewildered, that we fly eagerly to the nearest
authority to help us out of the scrape. It generally happens, in these
cases, that the reference does not prove very satisfactory, because
the actual circumstances with which we are engaged are rarely similar
in all their bearings to those with which we compare them; and when
this is not the case, the blindfold method of proceeding in the beaten
path is very apt to mislead.

As an illustration of this kind of deception, it may be stated that
navigators, whose actual experience has not extended to the tropical
regions, are very apt, in poring over the voyages of others, to
acquire, insensibly, a very confident notion that each of the great
Trade-winds blowing on different sides of the Line (the North-east and
the South-east by name), are quite steady in their direction; and
that, in the equatorial interval which lies between them, only calms
and light winds are to be found. Moreover, inexperienced persons
generally believe this interval to be equally divided by the equator,
and that both the breadth and the position of this calm region
continue unchanged throughout the whole year. Now, here are four
important mistakes,--important both in a scientific and in a practical
point of view. For, 1st, Not calms and squalls alone, but occasionally
fresh and steady winds, are found between the Trades; 2ndly, The belt
called the Variables is by no means equally divided by the equator;
neither, 3rdly, is that belt stationary in its position; nor, 4thly,
is it uniform in its breadth. It will thence be easily understood,
even by a person who has never quitted one of the midland counties in
England, and to whom the ocean is an unseen wonder, that a new-comer
to the tropical regions, his head loaded with these false views, will
be very apt to mistake his own ignorance for the caprice of Nature,
and perhaps call out, as I once heard a man do, in all the agony of
impatience caused by a protracted head-wind,--"Now, this is really
scandalous usage of the clerk of the weather-office!" The scandal,
however, lay not so much with the clerk's usage as with his own
limited knowledge; for if, at the very time of his imprecation,
instead of abusing the foul wind, and keeping his yards braced sharp
up, and making his sails stand like a board, the grumbler had known
how to take advantage of it, and had kept away two or three points,
set his fore-topmast studding-sail, and flanked across or through the
breeze which he had in vain tried to beat against, he might not only
have saved his temper, but have made his passage in half the time.

I am not sure that, in the whole range of this extensive subject,
there could be picked out an instance more in point to what has just
been said, than these interesting phenomena of the Trade-winds. To
sailors of every age and rank, and especially to naval officers, an
acquaintance with the laws which regulate these extraordinary aerial
currents must be of great importance. For a commander may be ordered,
at a moment's warning, either to carry his own ship, or to lead a
squadron, or to guard a convoy, from the northern to the southern
hemisphere, or perhaps from the West to the East Indies. If, however,
he have not previously made a tropical voyage or two, or have not
studied the subject in its genuine theoretical spirit, as well as in
the log-books of his predecessors, he may expect to find himself most
wofully embarrassed, both on entering and on leaving the Trades.

Independently of all such public objects concerned in these inquiries,
there appears to exist a very general interest in the Trade-winds,
sufficiently strong to engage the attention even of unprofessional
persons. These vast currents of air, which sweep round and round the
globe, in huge strips of more than twelve hundred miles in width, are
in a manner forced on every one's notice, from contributing to that
boundless interchange of the productions of distant regions by which
modern times are so agreeably distinguished from the old.

The great Monsoons, again, of the Indian and China oceans play almost
as important a part in this grand nautical drama along the coasts of
those remote countries. These great phenomena will be found to obey
precisely the same laws as their less fluctuating brethren the mighty
Trades; and hence springs one of the chief delights of science when
its study is conducted in a proper spirit. If the pursuit of truth be
engaged in with sincerity, phenomena apparently the most opposite in
character, for example, winds in different parts of the earth, but in
the same latitude, blowing in totally different directions at the same
season of the year, will always prove in the end illustrative of one
another, and of their common theory.

FOOTNOTES:

[2] On the renewal of their Charter, in 1833, the East India Company
ceased to be traders, and these noble ships no longer sail under the
Company's flag.




CHAPTER VI.

THE TRADE WINDS.


There are few things more curious in the history of human knowledge
than the establishment of extensive errors as to matters of fact, and
the perverse tenacity with which they retain their hold on the public
mind. In some cases it would almost seem that the pleasure which
springs from genuine philosophical inquiry is subordinate to that
which arises from the indolent process of taking things for granted.
This applies peculiarly to the phenomena of the Trade-winds,
respecting which many erroneous ideas are generally entertained. To
professional men these fallacies are calculated to prove extremely
mischievous; while even to persons not directly connected with the
sea, the existence of error may often be injurious: and, although it
is not very easy to explain these things in a popular way, I shall
attempt to give a description of the facts as they really exist.

The main characteristics may easily be described.

The great belt of the earth's surface, nearly three thousand miles in
width, lying between the tropics (from 23-1/2 deg. north to 23-1/2 deg. south
latitude), is the chief region of the Trade-winds; though in some
parts of the world they extend to the latitude of 28 deg. both north and
south of the equator; while at other places well within the tropics,
and even close to the line, totally different winds prevail. It is
only in the open parts of the Pacific and Atlantic oceans that the
true Trade-winds blow. In the Indian and China seas, and in many other
portions of the great tropical belt, periodical winds, called
Monsoons, are found. These shifting Trades exact the closest study
from the practical navigator, in consequence of their extensive
variety and seeming complication. But they are not less deserving the
attention of merely curious inquirers, from the beautiful manner in
which these modifications of the regular breezes obey the same general
laws which direct the grand phenomena of the Trades. Indeed, the most
extensive observation serves only to link the whole into one
harmonious chain or series of explanations, exhibiting the uniformity
as well as the exquisite adaptability of Nature, even in those
departments called "inconstant," where she is supposed to be most
capricious.

The only general assertion that can safely be made with respect to the
Trade-winds is, that they blow more or less from the eastern half of
the compass towards the western. On the north side of the equator, the
north-east Trade-winds blow; and on the south side, the south-east
Trade-winds. These two names have undoubtedly contributed to mystify
the subject by naturally suggesting to the imagination currents of air
blowing respectively from the north-east and the south-east, or at an
angle of 45 deg. with the meridian. And I have even seen sailors (old
sailors too) quite surprised, and rather provoked, when they have
encountered very different winds in those parts of their voyage,
where, being misled by the force of names alone, they had taught
themselves to expect a regular breeze from a particular quarter. But,
in point of fact, the Trade-winds do very seldom blow directly from
north-east and south-east; neither are they uniform in their direction
on the same spot at different seasons of the year, nor is their
strength uniform from month to month. I may add, that the equatorial
limits, or bounding lines, of the trades, are not steadily confined to
the same latitude. In short, so far from these winds being perfectly
fixed in direction, force, and position, they are subject to very
considerable mutations, dependent on the position of the sun. Their
vast nautical value, in fact, as well as philosophical curiosity,
turns mainly on their uniformity, which, in spite of all the
fluctuations alluded to, gives them a very distinctive character.

Dr. Young and Hadley, the great authorities on the subject, are both
wrong in their conclusions.[3] Where Hadley obtains his "experience"
he does not tell; but certain it is, that no sailor who ever crossed
the equinoctial line could possibly have furnished him with two of his
principal statements. The Trades are not strongest near the equator,
as he states, nor when they reach that district do they blow along it,
or in a parallel direction, but almost always at right angles to it.

If the earth had no motion on its axis, but were surrounded as at
present with an atmosphere, and if the sun moved round and round it
exactly above the equator, without varying his declination, the
following effects would ensue: That portion of the earth lying, say
thirty degrees, on each side of the equator, being more exposed to the
action of the sun than those further from it, would become much
warmer; while the superincumbent air, being greatly heated by the
contact, would expand, or become specifically lighter, and would
consequently rise. The adjacent air, both on the north and south,
being cooler, and, of course, heavier, would rush in to supply the
place of the heated air. This air coming from the regions beyond the
tropics would, in its turn, be heated, and rise on reaching the warmer
equatorial regions, giving place to a fresh supply, which, it is easy
to see, must be furnished by the descent of that portion of air
formerly heated at the equator, raised into the cold regions of the
sky, and forced into a regular circuit by fresh elevations of heated
air. All these and many other interesting results are clearly
developed in Daniell's Meteorological Essays, a book which every one
at all interested in such inquiries will find it advantageous to
study. The first edition of this work was published in 1823, some
years after these speculations had been forced upon my notice by a
long course of service between the tropics.

It will be understood, that, as long as we imagine the globe at rest
while this circulation is going on, the course of the lower air along
the surface would be directly towards the equator, from due north in
one hemisphere, and from due south in the other; while in the upper
regions the currents would follow the opposite directions, and stream
towards the poles. But the instant we conceive the earth put into
rotatory motion from west to east, a change would take place in the
course of these aerial currents, both above and below. It must be
recollected that a volume of air, when once put in motion, will move
on, like any other body, by the mere force of its own momentum, till
that motion is destroyed by its friction against the substances along
or through which it is impelled. Any one who has observed the ring of
smoke sometimes projected from the mouth of a cannon will be sensible
that this is true.

It may likewise be of use, before going further, to consider, that, if
the globe, instead of being unequally heated; were equally heated at
all parts, from pole to pole, and being surrounded by an atmosphere,
were then made to revolve on its axis, it would carry the atmosphere
round with it exactly at the rate at which it was itself going. That
portion of the air in contact with the equator would move about 1000
miles in one hour, while that in latitude 90 deg. would be as motionless
as the poles themselves.

From this it will be seen, that, while the equator moves at the rate
of 1000 miles an hour, the district about the latitude 30 deg. moves only
860, or 140 miles slower. The average whirling velocity of the earth's
easterly motion, in the space between the equator and latitude 30 deg.,
may be stated at 950 miles an hour; and that of the belt lying between
30 deg. and 40 deg., at about 800 miles.

In the hypothetical case, above suggested, of the whole surface being
equally heated, and consequently the whole atmosphere at the same
temperature, there would be a universal calm, whatever might be the
rotatory motion impressed upon the earth. If, however, we next
suppose, what really is the case, that the air over the tropical
region is more heated than that which is farther from the equator,
this rarefied air will instantly ascend, and occupy a place above the
colder and denser air, which will flow in from the belts lying beyond
the tropics.

When the comparatively slow-moving air of the temperate zone, lying
beyond the tropics, first comes in contact with those quicker-moving
parts of the earth forming the tropical edges of the torrid zone, the
apparent motion of the air from the east, caused by the relative
difference of the rotatory velocity between the air and earth, is
great, compared to the other motion of the air, caused by its being
drawn directly towards the equator, to supply the place of the heated
portions raised into the sky. Consequently, at the tropical borders of
both Trades the wind is found to blow very nearly from the east point.

Since the cool air of the temperate and comparatively slow-moving
zones beyond the tropics is thus drawn towards the equator, and comes
successively in contact with parallels of latitude moving faster and
faster towards the east, there must be gradually imparted to it, by
the increased friction, a considerable degree of the increased
rotatory velocity belonging to the low latitudes it has now reached;
that is to say, there will be less and less difference of velocity
between the easterly motion of this temperate air and the easterly
motion of the earth; and, consequently, the wind, as it approaches the
equator, will appear to blow less and less directly from the
eastward. But, while the earth's rotation within the tropics is thus
acting on the slower-moving air which has travelled to it from beyond
the tropics, with increased friction at every successive moment, there
has been no such powerful counteracting influence in operation to
diminish the meridional motion impressed on the air in question; for,
although in proceeding from the tropics towards the equator, the wind
might, at first sight, be supposed to have its speed somewhat lessened
by friction along the earth's surface, the retardation due to this
cause, if there be any at all, must be inconsiderable, compared to
that which affects the motion caused by the difference in the rotatory
velocity of the earth at the different parallels. It must be
recollected, also, that there is a constant demand for fresh air from
the north and south, to occupy the place of the heated and rarefied
air which is raised up in the torrid zone; and this demand being
pretty equal, the motion it produces on the air in the direction of
the meridian must likewise be uniform.

If it be admitted that all the easterly character of the Trade-winds
is due to the difference of velocity between the rotation of the
torrid zone of the earth from west to east, and that of the air
impressed only with the slower rotatory motion to the east of the
temperate zone, it will follow, that, if this difference of velocities
between the earth and the air in contact with it be diminished or
annihilated, the easterly character of these winds will be diminished
or annihilated likewise. At the same time, there is no cause in
operation, that I can discover, to alter the direction of the
meridional motion, as it may be called, of the Trade-winds, or that
by which they are impelled directly towards the equator.

At first starting from the temperate zone, on its voyage to the
equator, the cold air of that slow-moving region is impressed with a
rotatory velocity of only 800 miles per hour to the eastward, but it
soon comes over parts of the earth moving more than 100 miles per hour
faster to the eastward than itself. The difference of velocity in the
earth's rotation between latitudes 30 deg. and 20 deg. is 74 miles an hour,
while between 20 deg. and 10 deg. it is only 45 miles, and in the next ten
degrees the difference in rate per hour is reduced to 15 miles.

The velocity with which the air drawn from beyond the tropics travels
along the sea towards the equator is probably not above twenty miles
an hour, a rate slow enough to allow time for the
constantly-increasing friction of the earth's rotation to act upon it,
and draw it more and more entirely to the east. By the time it has
reached the equatorial regions, the friction of the earth's surface
has operated long enough to carry the air completely along with it;
and, of course, all relative motion being done away with, everything
easterly in the character of the Trade-winds will be at an end.

But, although this constantly-increasing friction of the earth's
rotation has thus annihilated all relative easterly motion between the
air and earth, that air still retains its motion towards the equator;
and accordingly we do find the Trade-winds, at their equatorial
limits, blowing, not from the east, as Hadley, Dr. Young, and others,
conceived, but directly from the north and from the south
respectively. The strength and velocity of the Trades at these places
is, in general, considerably diminished, chiefly, perhaps, by the air
becoming heated, and rising up rather than flowing along; and also, no
doubt, by the meeting of the two opposite currents of air--one from
the north, the other from the south--which produces the intermediate
space called the Calms, or the Variables.

In strict conformity with these theoretical views, the clouds above
the Trades are almost invariably observed to proceed in the contrary
direction to the winds below. On the top of the Peak of Teneriffe I
found a gentle breeze blowing from the south-westward, directly
opposite to the course of the Trade-wind.

The more detailed circumstances usually met with in that part of a
voyage to India which lies between 30 deg. north and 30 deg. south, and which
I am about to describe, will now, I imagine, be readily understood.
Before setting out, however, I must strongly recommend any one wishing
to see these matters clearly, to have them fixed in his mind to useful
purpose, to follow both the theoretical and the practical parts of
this explanation with the assistance of a terrestrial globe.

Most ships touch at Madeira, either to take in a stock of wine, to get
fruit and vegetables, or to form a pleasant break in the early and
most disagreeable part of the voyage. Some ships pass barely in sight
of the high mountain which rises above the town of Funchal, and
satisfy themselves with taking sights for verifying the rates of their
chronometers when on the meridian of the island; while others
tantalise their passengers still more by sweeping through the roads,
without anchoring, or communicating with the shore. The captains by
such ships are pretty deeply, if not very loudly, abused by all hands,
passengers especially, who are perhaps the most dissatisfied, because
the most idle, of mortals. Shortly after leaving Madeira, which is in
32-1/2 deg. north latitude, a ship may expect to meet the Trades; but she
cannot calculate with any certainty upon catching them till she
arrives at the parallel of 28 deg.. On first reaching the Trade-wind it
will be found to blow very nearly from due east, and with this a
course is easily steered past or amongst the Canaries, and thence for
the Cape de Verdes. Some navigators pass within this group, others
keep so far out as barely to make San Antonio; and this, I think, is
considered the best route. As the ship proceeds to the southward, the
wind draws gradually round from the east to north-east, and eventually
to north-north-east, and even to north, at the southern margin of the
north-east Trade-wind.

The position of this margin or southern edge, which in technical
language is called the equatorial limit of the Trade, varies
considerably with the season of the year. From December to May
inclusive it frequently reaches as far as the 3rd degree of north
latitude, though it ranges about 5 deg. and 6 deg. north. From June to
November it is shifted back as far, sometimes, as 13 deg. north, but it
seldom extends as far south as 8 deg. north. Subjects which are treated of
in a series of tables showing the equatorial limits of both
Trade-winds, deduced by the late Captain James Horsburgh, hydrographer
of the East India Company, from the observations of 238 ships. These
tables show very clearly the effect of the absence or presence of the
sun in shifting the limits of the Trades, drawing them after him, as
it were. The presence of the sun in either hemisphere obstructs
considerably the regularity and strength of the Trade-winds in that
hemisphere, and _vice versa_.

The great difficulty experienced in making the outward-bound voyage
commences after the ship has been deserted by the north-east Trade,
for she has then to fight her way to the southward across the region
of Calms and Variables. But as these Variables blow generally from the
southward and westward, from a cause afterwards to be explained, it is
obvious enough why this part of the homeward voyage is always more
easily made than the outward passage. These southerly breezes, which
are met with in the Variables, blow at times with considerable force,
and greatly perplex the young navigator, who, trusting perhaps to some
of the erroneous published accounts, not unnaturally reckons upon
meeting the regular Trade-wind, blowing, as he supposes, from the east
near the equator, not from the south; still less is he prepared or
pleased to find it blowing from the south-westward.

This troublesome range, intervening between the two Trades, varies in
width from 150 to more than 500 miles. It is widest in September, and
narrowest in December or January. I now speak more particularly of
what happens in the Atlantic. In the wide Pacific, far from land,
fewer modifying circumstances interfere with the regular course of the
phenomena, than in the comparatively narrow sea formed by the opposite
shoulders of Africa and South America.

Calms, also, are met with in this intermediate region, or purgatory of
the outward-bound voyage, and occasionally violent tornados or
squalls, which in a moment tear away every rag of canvas from a ship's
yards. For several hours at a time, also, rain falls down in absolute
torrents. Even when the weather clears up, and a fresh breeze comes,
it is generally from the southward, directly in the outward-bound
navigator's teeth. He must have patience, however, and strive to make
the most of it by keeping on that tack by which most southing is to be
gained. It is now, I believe, generally held to be the best practice
to place the ship between 18 deg. and 23 deg. of west longitude on losing the
north-east Trade; and likewise to endeavour, if possible, to cross the
equator somewhere between these two longitudes. Before reaching the
line, however, the navigator will almost always be met by the
south-east Trade-wind. From January to May he may expect to meet it in
1 deg. or 2 deg. north latitude; but in summer and autumn he will find the
northern or equatorial limit of the south-east Trade a degree or two
still further to the northwards of the lines.

On first encountering the south-east Trade an outward-bound ship is
obliged to steer much more to the westward than she wishes to do, in
consequence of the wind blowing so directly towards the equator, and
not along it, as some of the books will insist on, in spite of Nature.
So that if she be a dull sailer she may have some difficulty in
weathering the coast of Brazil about Cape St. Roque. As she proceeds
onwards, however, and makes a little more southing, the wind will haul
more and more round from the south to the south-east, then
east-south-east, and eventually to east at the southern limit of the
Trade-wind. An inexperienced sailor, on first entering the south-east
Trade, is very apt to be too solicitous about making southing, and
hugs the wind much too close; whereas he ought rather to keep his ship
off a little, give her a fathom or two of the fore and main sheets,
and take a small pull of the weather topsail and top-gallant braces,
to ensure making good way through the water. Indeed, many officers go
so far as to recommend flanking across the south-east Trade with a
fore-topmast studding-sail set. Although, I think, there can be no
doubt of the soundness of this advice, I confess that it does require
no inconsiderable degree of faith to adopt a course, which,
apparently, takes the ship not directly away from her object, but very
much out of the straight road. In this respect, it may be remarked
that the scale of navigation on every Indian voyage is so great, and
the importance of getting into those parallels where favourable
breezes are certain to be met with, of so much more consequence than
the gain of mere distance, that two or three hundred miles to the
right or left, or even twice that space, is often not to be regarded.
Accordingly, in cutting or flanking across the south-east Trade-wind,
the object, it should be remembered, is not to shorten the distance,
but to reach those latitudes where strong westerly gales are to be met
with, by help of which five hundred or a thousand miles of lost
distance are speedily made up, and the rest of the passage secured.

In those regions lying beyond the southern tropic westerly winds
prevail during the greater part of the year, exactly as we find on
this side of the northern tropic. In the southern hemisphere, and far
from the land, the wind may be said to blow from the westward almost
as steadily as the Trades do from the eastward. The great object,
therefore, for an outward-bound ship is to get far enough south to
ensure this fair wind. Beyond the latitude of 30 deg., and as far as 40 deg.,
this purpose will generally be answered.

We are sufficiently familiar in England with the fact of westerly
winds prevailing in the Atlantic. From a list of the passages made by
the New York sailing packets across the Atlantic, during a period of
six years, it is shown that the average length of the voyage from
Liverpool to America, that is, towards the west, was forty days; while
the average length of the homeward passage, or that from west to east,
was only twenty-three days. And it may fix these facts more strongly
in the recollection, to mention that the passage-money from England to
America (in the days of sailing packets) was five guineas more than
that paid on the return voyage.

This prevalence of westerly winds beyond the tropics is readily
explained by the same reasoning which has been applied to the Trades
blowing within them. The swift moving air of the torrid zone, on being
rarefied and raised up, flows along towards the poles, and in a
direction from the equator, above the cooler and slower-moving air,
which, as I have already described, is drawn along the surface of the
earth from the temperate regions beyond the tropics. When the rarefied