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THE PHYSICAL GEOGRAPHY 
OF THE SEA. 


BY 


LIEUTENANT M. F. MAURY, LL.D. 


LONDON: 
T., NELSON AND SONS, PATERNOSTER ROW; 


EDINBURGH; AND NEW YORK, 


1873. 


3 
_ if s 


Digitized by the Internet Archive 
in 2010 with funding from 
University of Toronto 


http://www.archive.org/details/physicalgeograp00maur 


INTRODUCTION TO THE FIRST EDITION—1855. 


ee ee 


THE primary object of “ The Wind and Current Charts,” out of 
which has grown this Treatise on the Physical Geography of the 
Sea, was to collect the experience of every navigator as to the winds 
and currents of the ocean, to discuss his observations upon them, 
and then to present the world with the results on charts for the 
improvement of commerce and navigation. 

By putting down on a chart the tracks of many vessels on the 
same voyage, but at different times, in different years, and during all 
seasons, and by projecting along each track the winds and currents 
daily encountered, it was plain that navigators hereafter, by consult- 
ing this chart, would have for their guide the results of the combined 

_experience of all whose tracks were thus pointed out. 

Perhaps it might be the first voyage of a young navigator to the 
given port, when his own personal experience of the winds to be 
expected, the currents to be encountered by the way, would itself be 
blank If so, there would be the Wind and Current Chart. It would 
spread out before him the tracks of a thousand vessels that had pre- 
ceded him on the same voyage, wherever it might be, and that, too, 
at the same season of the year. Such a chart, it was held, would 
show him not only the tracks of the vessels, but the experience also 
of each master as to the winds and currents by the way, the tem- 
perature of the ocean, and the variation of the needle. All this could 
be taken in at a glance, and thus the young mariner, instead of grop- 
ing his way along until the lights of experience should come to him 
by the slow teachings of the dearest of all schools, would here find 
at once that he had already the experience of a thousand navigators 
to guide him on his voyage. He might, therefore, set out upon his 
first voyage with as much confidence in his knowledge as to the winds 
and currents he might expect to meet with, as though he himself had 
already been that. way a thousand times before. 


lV INTRODUCTION TO FIRST EDITION. 


Such a chart could not fail to commend itself to intelligent ship- 
masters, and such a chart was constructed for them. They took it 
to sea, they tried it, and to their surprise and delight they found that, 
with the knowledge it afforded, the remote corners of the earth were 
brought closer together, in some instances by many days’ sail. The 
passage hence to the equator alone was shortened ten days. Before 
the commencement of this undertaking, the average passage to Cali- 
fornia was 183 days; but with these charts for their guide, navigators 
have reduced that average, and brought it down to 135 days. 

Between England and Australia, the average time going, without 
these charts, is ascertained to be 124 days, and coming, about the 
same; making the round voyage one of about 250 days on the 
average. These charts, and the system of research to which they 
have given rise, bid fair to bring that colony and the mother country 
nearer by many days,—reducing in no small measure the average 
duration of the round voyage.* 

At the meeting of the British Association of 1853, it was stated by 
a distinguished member,—and the statement was again repeated at 
its meeting in 1854,—that in Bombay, whence he came, it was esti- 
mated that this system of research, if extended to the Indian Ocean, 
and embodied in a set of charts for that sea, such as I have been 
describing, would produce an annual saving to British commerce, in 
those waters alone, of one or two millions of dollars ;+ and in all seas, 
of ten millions.£ 


* The outward passage, it has since been ascertained, has been reduced to 97 days on the 
average, and the homeward passage has been made in 63. 

+ See Inaugural Address of the Earl of Harrowby, President of the British Association, at 
its twenty-fourth meeting. Liverpool, 1854. 

t. . . ‘‘Now let us make a calculation of the annual saving to the commerce of the 
United States effected by those charts and sailing directions. According to Mr. Maury, the 
average freight from the United States to Rio Janeiro is 17.7 cts. per ton per day; to Aus- 
tralia. 20 cts.; to California, also, about 20 cts. The mean of this is a little over 19 cents 
per ton per day; but to be within the mark, we will take it at 15, and include all the ports 
of South America, China, and the East Indies. 

‘The sailing directions have shortened the passages to California 30 days, to Australia 20, 
to Rio Janeiro 10. The mean of this is 20, but we will take it at 15, and also include the 
above-named ports of South America, China, and the East Indies. 

“We estimate the tonnage of the United States engaged in trade with these places at 
1,600,000 tons per annum. 

“With these data, we see that there has been effected a saving for each one of these tons 


INTRODUCTION TO FIRST EDITION. Vv 


A system of philosophical research which is so rich with fruits 
and abundant with promise, could not fail to attract the attention 
and commend itself to the consideration of the seafaring community 
of the whole civilized world. It was founded on observation; it 
was the result of the experience of many observant men, now 
brought together for the first time, and patiently discussed. The 
results tended to increase human knowledge with regard to the sea 
and its wonders, and therefore the system of research could not be 
wanting in attractions to right-minded men. 

The results of the first chart, however, though meagre and unsatis- 
factory, were brought to the notice of navigators; their attention 
was called to the blank spaces, and the importance of more and bet- 
ter observations than the old sea-logs generally contained was urged 
upon them. 

They were told that if each one would agree to co-operate in a 
general plan of observations at sea, and would send regularly, at the 
end of every cruise, an abstract log of their voyage to the National 
Observatory at Washington, he should, for so doing, be furnished, 
free of cost, with a copy of the charts and sailing directions that 
_ might be founded upon those observations. 

The quick, practical mind of the American shipmaster took hold 
of the proposition at once. To him the field was inviting, for he 
saw in it the promise of a rich harvest, and of many useful results. 

So, in a little while, there were more than a thousand navigators 
engaged day and night, and in all parts of the ocean, in making and 
recording observations according to a uniform plan, and in further- 
ing this attempt to increase our knowledge as to the winds and 
currents of the sea, and other phenomena that relate to its safe navi- 
gation and physical geography. 

To enlist the service of such a large corps of observers, and to 
have the attention of so many clever and observant men directed tc 


of 15 cents per day for a period of 15 days, which will give an aggregate of 2,250,000 dollars 
Saved per annum. This is on the outward voyage alone, and the tonnage trading with all 
other parts of tlie world is also left out of the calculation. Take these into consideration, 
and also the fact that there is a vast amount of foreign tonnage trading between these places 
and the United States, and it will be seen that the annual sum saved will swell to an enormous 
amount.”— Ertract from Hunt's Merchant's Magazine, May, 1854. 


v1 INTRODUCTION TO FIRST EDITION. 


the same subject, was a great point gained : it was a giant stride in 
the advancement of knowledge, and a great step toward its spread 
upon the waters. 

Important results soon followed, and great discoveries were made, 
These attracted the attention of the commercial world, and did not 
escape the notice of philosophers everywhere. 

The field was immense, the harvest was plenteous, and there were 
both need and room for more labourers. Whatever the reapers 
should gather, or the merest gleaner collect, was to go to the benefit 
of commerce and navigation—the increase of knowledge—the good 
of all. 

Therefore, all who use the sea were equally interested in the 
undertaking. The Government of the United States, so considering 
the matter, proposed a uniform system of observations at sea, and 
invited all the maritime states of Christendom to a conference upon 
the subject. 

This conference, consisting of representatives from France, England, 
and Russia, from Sweden and Norway, Holland, Denmark, Belgium, 
Portugal, and the United States, met in Brussels, August 23, 1853, 
and recommended a plan of observations which should be followed 
on board the vessels of all friendly nations, and especially of those 
there present in the persons of their representatives. 

Prussia, Spain, Sardinia, the Holy See, the free city of Ham- 
burg, the republics of Bremen and Chili, and the empires of Austria 
and Brazil, have since offered their co-operation also in the same plan. 

Thus the sea has been brought regularly within the domains of 
philosophical research, and crowded with observers. 

In peace and in war these observations are to be carried on; and, 
in case any of the vessels on board of which they are conducted may 
be captured, the abstract log—as the journal which contains these 
observations is called—is to be held sacred. 

Baron Humboldt is of opinion that the results already obtained 
from this system of research are sufficient to give rise to a new 
department of science, which he has called the PHystcat Gxro- 
GRAPHY OF THE SEA. If so much has already been accomplished 
hy one nation, what may we not expect, in the course of a few years, 
from the joint co-operation of so many? 


INTRODUCTION TO FIRST EDITION. Vil 


Rarely before has there been such a sublime spectacle presented 
to the scientific world: all nations agreeing to unite and co-ope- 
rate in carrying out one system of philosophical research with regard 
to the sea. Though they may be enemies in all else, here they are 
to be friends. Every ship that navigates the high seas, with these 
charts and blank abstract logs on board, may henceforth be regarded 
as a floating observatory, a temple of science. The instruments 
used by every co-operating vessel are to be compared with stand- 
ards that are common to all; so that an observation that is made 
anywhere, and in any ship, may be referred to and compared with 
all similar observations by all other ships in all parts of the world. 

But these meteorological observations which this extensive and 
admirable system includes will relate only to the sea. This is not 
enough. The plan should include the land also, and be universal. 
Other great interests of society are to be benefited by such extension 
no less than commerce and navigation have been. A series of sys- 
tematic observations, directed over large districts of country, nay, 
over continents, to the improvement of agricultural and sanitary 
meteorology, would, I have no doubt, tend to a development of 
many interesting, important, and valuable results. 

The agricultural societies of many states of the Union have 
addressed memorials to the American Congress, asking for such 
extension; and it is hoped that that enlightened body will not fail 
favourably to respond. 

This plan contemplates the co-operation of all the states of Chris- 
tendom, at least so far as the form, method, subjects of observations, 
time of making them, and the interchange of results are concerned. 
I hope that my fellow-citizens will not fail to second and co-operate 
in such a humane, wise, and noble scheme. The Secretary of the 
Navy, taking the enlarged and enlightened views which do honour 
to great statesmen, has officially recommended the adoption of such 
a system, and the President has asked the favourable consideration 
thereof by Congress. These researches for the land look not only to 
the advancement of the great interests of sanitary and agricultural 
meteorology, but they involve also a study of the laws which regu- 
late the atmosphere, and a careful investigation of all its phenomena. 

Another beautiful feature in this system is, that it costs nothing 


vill INTRODUCTION TO FIRST EDITION. 


additional. The instruments that these observations at sea call for 
are such as are already in use on board of every well-conditioned 
ship, and the observations that are required are precisely those which 
are necessary for her safe and proper navigation. 

Great as is the value attached to what has been accomplished 
by these researches, in the way of shortening passages and lessening 
the dangers of the sea, a good of higher value is, in the opinion of 
many seamen, yet to come, out of the moral, the educational in- 
fluence which they are calculated to exert upon the seafaring com- 
munity of the world. A very clever English shipmaster, speaking 
recently of the advantages of educational influences among those 
who intend to follow the sea, remarks :— 

“To the cultivated lad there is a new world spread out when he 
enters on his first voyage. As his education has fitted, so will he 
perceive, year by year, that his profession makes him acquainted 
with things new and instructive. His intelligence will enable him 
to appreciate the contrasts of each country, in its general aspect, 
manners, and productions, and in modes of navigation adapted to 
the character of coast, climate, and rivers. He will dwell with in- 
terest on the phases of the ocean,—the storm, the calm, and the 
breeze, and will look for traces of the laws which regulate them. 
All this will induce a serious earnestness in his work, and teach him 
to view lightly those irksome and often offensive duties incident to 
the beginner.”* 

And that these researches have such an effect, many noble- 
hearted mariners have testified. Captain Phinney, of the American 
ship Gertrude, writing from Callao, January 1855, thus expresses 
himself :— 

“Having to proceed from this to the Chincha Islands, and remain 
three months, I avail myself of the present opportunity to forward to 
you abstracts of my two passages over your southern routes, although 
not required to do so until my own return to the United States next 


* “The Log of a Merchant Officer, viewed with reference to the Education of Young 
Officers and the Youth of the Merchant Service. By Robert Methren, commander in the 
Peninsular and Oriental Company, and author of the ‘ Narrative of the Blenheim Hurricane 
of 1851.""" Londun: John Weale, 59 High Holborn; Smith, Elder, and Co., Cornhill; 
Ackerman and Co., Strand. 1854. 


INTRODUCTION TO FIRST EDITION. 18 


summer, knowing that you are less amply supplied with abstracts of 
voyages over these regions than of many other parts of the ocean ; 
and, such as it is, I am happy to contribute my mite toward furnish- 
ing you with material to work out still farther toward perfection 
your great and glorious task, not only of pointing out the most 
speedy routes for ships to follow over the ocean, but also of teaching 
us sailors to look about us, and see by what wonderful manifestations 
of the wisdom and goodness of the great God we are continually sur- 
rounded. 

“For myself, I am free to confess that for many years I com- 
manded a ship, and, although never insensible to the beauties of 
nature upon the sea or land, I yet feel that, until I took up your 
work, I had been traversing the ocean blindfolded. I did not think ; 
I did not know the amazing and beautiful combination of all the 
works of Him whom you so beautifully term ‘The Great First 
Thought.’ 

“T feel that, aside from any pecuniary profit to myself from your 
labours, you have done me good asa man. You have taught me to 
look above, around, and beneath me, and recognise God’s hand in 
every element by which I am surrounded. I am grateful for this 
personal benefit. Your remarks on this subject, so frequently made 
in your work, cause in me feelings of the greatest admiration, 
although my capacity to comprehend your beautiful theory is very 
limited. 

“The man of such sentiments as you express will not be displeased 
with, or, at least, will know how to excuse, so much of what (in ¢ 
letter of this kind) might be termed irrelevant matter. I have there- 
fore spoken as I feel, and with sentiments of the greatest respect.” 

Sentiments like these cannot fail to meet with a hearty response 
from all good men, whether ashore or afloat. 

Never before has such a corps of observers been enlisted in the 
cause of any department of physical science as is that which is now 
about to be engaged in advancing our knowledge of the Physical 
Geography of the Sea, and never before have men felt such an interest 
with regard to this knowledge. 

Under this term will be included a philosophical account of the 
wiuds and currents of the sea; of the circulation of the atmosphere 


xX INTRODUCTION TO FIRST EDITION. 


and ocean ; of the temperature and depth of the sea ; of the wonders 
that lie hidden in its depths; and of the phenomena that display 
themselves at its surface. In short, I shall treat of the economy of 
the sea and its adaptations—of its salts, its waters, its climates, and 
its inhabitants, and of whatever there may be of general interest in 
its commercial uses or industrial pursuits, for all such things pertain 
to its PaysicaL GEOGRAPHY. 

The object of this little book, moreover, is to show the present 
state, and from time to time the progress, of this new and beautiful 
system of research, as well as of this interesting department of 
science ; and the aim of the author is to present the gleanings from 
this new field in a manner that may be interesting and instructive 
to all, whether old or young, ashore or afloat, who desire a closer 
look into “the wonders of the great deep,” or a better knowledge as 
to its winds, its adaptations, or its Physical Geography.* 


* There is an old and very rare book which treats upon some of the subjects to which 
this little work relates: it is by Count L. F. Marsigli, a Frenchman, and is called ‘‘ Natural 
Descripticn of the Seas." The copy to which I refer was translated into Dutch by Boer- 
haave, in 1786. 

The French count made his observations along the coast of Provence and Languedoc. 
The description only relates to that part of the Mediterranean. The book is divided into 
four chapters ;—the first, on the bottom and shape of the sea; the second, of sea water; the 
third, on the movements of sea water; and the fourth, of sea plants. 

He divides sea water into surface and deep-sea water; because, when he makes salt from 
surface water (not more than half a foot below the upper strata), this salt will give a red 
colour to blue paper, whereas the sait from deep-sea water will not alter the colour at all. 
The blue paper can only change its colour by the action of an acid. The reason why this 
acid (iodine?) is found in surface and not in deep-sea water is, it is derived from the air; 
but he supposes that the saltpetre that is found in sea water, by the action of the sun’s rays 
and the motion of the waves, is deprived of its coarse parts, and, by evaporation, embodied 
in the air, to be conveyed to beasts or plants for their existence, or deposited upon the 
earth’s crust, as it occurs on the plains of Hungary, where the earth absorbs so much of this 
saltpetre vapour. 

Donati, also, was a valuable labourer in this field. His inquiries enabled Mr. Trembley! 
to conclude that there are, ‘tat the bottom of the water, mountains, plains, valleys, and 
caverns, just as upon the land.” 

But by far the most interesting and valuable book touching the physical geography of 
the Mediterranean is Admiral Smyth's last work, entitled ‘The Mediterranean ; a Memoir, 
Physical, Historical, and Nautical. By Rear-Admiral William Henry Smyth, K.S.F., D.C.L.,” 
&c. London: John W. Parker and Son. 1854. 


1 Philosophical Transactions. 


INTRODUCTION TO THE SIXTH EDITION. 


ee 


THE department of the Physical Geography of the Sea is a new field 
of research: there is great activity in it; and it is the aim of the 
author of this work to keep its readers posted up with the improve- 
ments, the developments, and the contributions that are made in 
this interesting field from time to time. 

The present edition contains much that is new; for the fifth edition 
has been most carefully revised,—much of it has been recast and 
some parts omitted. 

The desire is, that this work shall keep pace with the progress of 
research. As it may be supposed, facts are sometimes misinterpreted 
or not understood when first developed. Whenever subsequent 
research shows such to have been the case, I have not hesitated to 
tear down whatever of conjecture or theory may have been built on 
unstable foundations, and to reconstruct according to the best lights. 

It is proper to say, that, in accounting for the various phenomena 
that present themselves, 1 am wedded to no theories, and do not 
advocate the doctrines of any particular school. Truth is my object. 
Therefore, when the explanation which I may have at any time 
offered touching any facts fails to satisfy further developments, it is 
given up the moment one is suggested which will account for the 
new, and equally as well for the old, system of facts. In every 
instance that theory is preferred which is reconcilable with the 
greatest number of known facts. The chapter of the Gulf Stream 
has been enriched with the results of recent investigation, and the 
theory of it further developed ; so, also, that on the Salts of the Sea, 
the Open Sea in the Arctic Ocean, the Basin of the Atlantic, and 
several others ; but these especially have been greatly improved. 


xu INTRODUCTION TO SIXTH EDITION. 


A separate chapter is now devoted to the Land and Sea Breezes, 
and extensive contributions have been made to that on Monsoons, 
Trade Winds, and Cyclones. Lieutenant Jansen. of the Dutch Navy, 
has helped me to enrich these with his fine thoughts. The reader 
will, I am sure, feel as I do, deeply indebted to him for so much 
instructive matter, set forth in his very delightful and pleasing 
manner. 


NATIONAL OBSERVATORY, WASHINGTON, 
April, 1856. 


Since the above date, explorations have been made in this 
interesting department of science, and new veins of precious ore 
have been hit upon. We have not yet gone deep enough into 
them to justify a final report.t 

In 1849 Congress passed an Act requiring the Secretary of the 
Navy to employ three small vessels in assisting me to perfect my 
discoveries. A few weeks ago, Lieutenant Berryman put to sea 
in the “ Arctic” on this duty. His attention was especially 
directed to deep-sea soundings along the great telegraphic plateau 
stretching from Newfoundland to Ireland. The results, so far, 
are of the highest interest. Among them is the discovery of a 
line of volcanic cinders along a line a thousand miles in length, 
and reaching entirely across the Gulf Stream where the submarine 
telegraph is to cross it. 

There is also Lieutenant Jansen’s experiments upon Ozone, 
which cast unexpected light upon the circulation of the atmo- 
sphere. 

Matter of more general or higher scientific importance than 
that contained in this new Edition is seldom gathered from any 
fields of research. 


December, 1856. 


1 Vide subsequent additions in the present Edition, Chapters xxi. xxii. 


EXPLANATION OF THE PLATES. 


Puate I. isa diagram to illustrate the circulation of the atmosphere (Chap. 
III.). The arrows and bands within the circumference of the circle are 
intended to show the calm belts, and prevailing direction of the wind on each 
section of those belts. The arrows exterior to the periphery of the circle— 
which is a section of the earth supposed to be made in the plane of the meridian 
—are intended to show the direction of the upper and lower strata of winds in 
the general system of atmospherical circulation; and also to illustrate how the 
air brought by each stratum to the calm belts there ascends or descends, as the 
case may be; and then, continuing to flow on, how it crosses over in the direc- 
tion in which it was travelling when it arrived at the calm zone. 

Puates II. and III. are drawings of Brooke’s Deep-sea Sounding Apparatus, 
for bringing up specimens of the bottom (§ 701). 

Puate LV. is intended to illustrate the extreme movements of the isotherms 
50°, 60°, 70°, &c., in the Atlantic Ocean during the year. The connection be- 
tween the law of this motion and the climates of the sea is exceedingly interesting. 

Prats V. is a section taken from one of the manuscript charts at the Obser- 
vatory. It illustrates the method adopted there for co-ordinating for the Pilot 
Charts the winds as reported in the abstract logs. For this purpose the ocean 
is divided into convenient sections,—usually five degrees of latitude by five de- 
grees of longitude: These parallelograms are then subdivided into a system of 
engraved squares, the months of the year being the ordinates, and the points of 
the compass being the abscisse. As the wind is reported by a vessel that passes 
through any part of the parallelogram, so it is assumed to have been at that time 
all over the parallelogram. From such investigations as this the Pilot Charts 
(§ 929) are constructed. 

Puave VI. illustrates the position of the channel of the Gulf Stream (Chap. I.) 
for summer and winter. The diagram A shows a thermometrical profile presented 
by cross-sections of the Gulf Stream, according to observations made by the 
hydrographical parties of the United States’ Coast Survey. The elements for 
this diagram were kindly furnished me by the superintendent of that work. 
They are from a paper on the Gulf Stream, read by him before the American 
Association for the Advancement of Science, at its meeting in Washington, 1854. 
Imagine a vessel to sail from the Capes of Virginia straight out to sea, crossing 
the Gulf Stream at right angles, and taking the temperature of its waters at the 
surface and at various depths. The diagram shows the elevation and depression 
of the thermometer across this section as they were actually observed by such a 
vessel. 

The black lines x, y, z, in the Gulf Stream, show the course which those 
threads of warm waters take (§ 57). The lines a, 6, show the computed drift 
route that the unfortunate steamer San Francisco would take after her terrible 
disaster in December 1853. 

Puate VII. is intended to show how the winds may become geological agents. 
It shows where the winds that, in the general system of atmospherical circula- 
tion, blow over the deserts and thirsty lands in Asia and Africa (where the 
annual amount of precipitation is small) are supposed to get their vapour; 
where, as surface winds, they are supposed to condense portions of it; and 
whither they are supposed to transport the residue thereof through the upper 
regions, retaining it until they again become surface winds. 

Puarg VIII. shows the prevailing direction of the wind during the year in all] 


XIV EXPLANATION OF THE PLATES. 


varts of the ocean, as derived from the series of investigations illustrated on 
Plate VII. It also shows the principal routes across the seas to various places. 
Where the cross-lines representing the yards are oblique to the keel of the vessel, 
they indicate that the winds are, for the most part, ahead; when perpendicular 
or square, that the winds are, for the most part, fair. The figures on or near 
the diagrams representing the vessels, show the average length of the passage in 
days. 

The arrows denote the prevailing direction of the wind; they are supposed to 
fly with it; so that the wind is going as the arrows point. The half-bearded and 
half-feathered arrows represent monsoons (§ 763), and the stippled or shaded 
belts the calm zones. 

In the regions on the polar side of the calms of Capricorn and of Cancer, 
where the arrows are flying both from the north-west and the south-west, the idea 
intended to be conveyed is, that the prevailing direction of the winds is Letween 
the uorth-west and the south-west, and that their frequency is from these two 
quarters in proportion to the number of arrows. 

Pate IX. is intended to show the present state of our knowledge with regard 
to the drift of the ocean, or, more properly, with regard to the great flow of polar 
and equatorial waters, and their channels of circulation as indicated by the ther- 
mometer (§ 889). Further researches will enable us to improve this chart. The 
most favourite places of resort for the whale—right in cold, and sperm in warm 
water—are also exhibited on this chart. 

Puiate X. exhibits the actual path of a storm, which is a type (§ 85) of the 
West Indian hurricanes. Mr. Redfield, Colonel Reid, and others, have traced 
out the paths of a number of such storms. All of this class appear to make for 
the Gulf Stream: after reaching it, they turn about and follow it in their course 
(§ 95). 

Mr. Piddington of Calcutta has made the East Indian hurricanes, which are 
similar to these, the object of special, patient, and laborious investigation. He 
calls them cyclones, and has elicited much valuable information concerning them, 
which may be found embraced in his ‘‘Sailor’s Horn-bvok,” ‘‘ Conversations 
about Hurricanes,” and numerous papers published from time to time in the 
Journal of the Asiatic Society. 

Pirates XI. and XII. speak for themselves. They are orographic for the 
North Atlantic Ocean, and exhibit completely the present state of our kuow- 
ledge with regard to the elevations and depressions in the bed of the sea; Plate 
XII. exhibiting a vertical section of the Atlantic, and showing the contrasts of 
its bottom with the sea-level in a line from Mexico across Yucatan, Cuba, San 
Domingo, and the Cape de Verds, to the coast of Africa, marked A on Plate XI. 

Puate XIII.—The data for this Plate are furnished by Maury’s Storm and 
Rain Charts, including observations for 107,277 days in the North Atlantic, and 
158,025 in the South; collated by Lieutenant J. J. Guthrie, at the Washington 
Observatory, in 1855. 

The heavy vertical lines, 5°, 10°, 15°, &c., represent parallels of latitude; the 
other vertical lines, months; and the horizontal lines, per cents., or the number 
of days in a hundred. 

The continuous curve line stands for phenomena in the North, and the 
broken curve line for phenomena in the South Atlantic. Thus the Gales’ Curve 
shows that in every hundred days, and on the average, in the month of January 
of different years, there have been observed, in the northern hemisphere, 36 
gales (36 per cent.) between the parallels of 50° and 55°; whereas during the same 
time and between the same parallels in the southern hemisphere, only 10 gales 
on the average (10 per cent.) have been reported. 

The fact is here developed that the atmosphere is in a more unstable condition 
in the North than in the South Atlantic; that we have more calms, more rains, 
more fogs, more gales, and more thunder in the northern than in the southern 
hemisphere, particularly between the equator and the 55th parallel. Beyond 
that the influence of Cape Horn becomes manifest. 


Chapter 
I. 


Il. 
III. 
IV. 
We 
VI. 


VII. 
Vill. 
IX. 
X. 
XI. 
XII. 
XIII. 
xO 
XV. 
XVI. 
XVII. 
XVIII. 
XIX. 
XX. 


XXI. 


CONTENTS. 


Tur GULF STREAM Pe wes aoe sie Rae 


INFLUENCE OF THE GULF STREAM UPON CLIMATES... eee 


Tur ATMOSPHERE aes “eS see ae5 ase 
LAND AND SEA BREEZES ... ses ns aes aes 
Rep Foes anp Sea Dust ... a ase ses Ses 


ON THE PROBABLE RELATION BETWEEN MAGNETISM AND THE 


CIRCULATION OF THE ATMOSPHERE ay wes ize 
CURRENTS OF THE SEA a ie ee aoe one 
Tuer Open Sea IN THE Arctic OCEAN Se sae Soe 
Tue SALTSOF THE SEA ... aes ae aoe a 
Tue EquaTorIAL CLoup-RinG sas owe aco ees 
On THE GEOLOGICAL AGENCY OF THE WINDS on eee 
Tur DEprus oF THE OCEAN — ee a “ds a 
Tur Basin oF THE ATLANTIC wes ese wee el 
THE WINDS Be me ob aco eae oor 
CLIMATES OF THE OCEAN ... S59 Sas aoe bor 
Tur DRIFT OF THE SEA ... ate one see eee 
STORMS ... eee 506 aco xe aes n68 
Routes ... nee occ eee vee uae oes 
BrussELS CONFERENCE, ETC. ab an ncn res 


Force oF THE TRADE WINDS OF THE SOUTHERN HEMISPHERE— 
PECULIARITIES IN ITS ATMOSPHERIC CIRCULATION ee 


THe SUBMARINE TELEGRAPH OF THE ATLANTIC se Mes 


THE 


PHYSICAL GEOGRAPHY OF THE SEA. 


CHAPTER I. 
THE GULF STREAM. 


Its Colour, § 2.—Theories, 5.—Captain Livingston’s, 6.—Dr. Franklin’s, 7.— 
Admiral Smyth and Mediterranean Currents, 8.—Trade Winds not the Cause 
of the Gulf Stream, 9.—Drift of Bottles, 12.—Sargasso Sea, 13.—Hypothetical 
System of Currents, 19.—Galvanic Properties of the Gulf Stream, 26.—Salt- 
ness of ditto, 29.—Effects produced upon Currents by Evaporation, 32.—Gulf 
Stream Roof-shaped, 39.—Effects of Diurnal Rotation upon Running Water, 
42.—Course of the Gulf Stream not altered by Nantucket Shoals, 52.—The 
Trough in the Sea through which the Gulf Stream flows has a Vibratory Mo- 
tion, 54.—Streaks of Warm and Cold Water in the Gulf Stream, 57.—Runs 
up Hill, 59.—A Cushion of Cold Water, 60. 

THERE is a river in the ocean. In the severest droughts 

it never fails, and in the mightiest floods it never over- 

flows. Its banks and its bottoms are of cold water, while 
its current is of warm. The Gulf of Mexico is its foun- 
tain, and its mouth is in the Arctic Seas. It is the Gulf 

Stream. There is in the world no other such majestic 

flow of waters. Its current is more rapid than the Missis- 

sippi or the Amazon, and its volume more than a thousand 
times greater. 

Its waters, as far out from the Gulf as the Carolina 
coasts, are of an indigo blue. ‘They are so distinctly 


marked, that their line of junction with the common sea 
A 


OHAPTER 
1G 


$1 
Gulf 
Stream 


§ 2 


Colour of 
ite waters 


bo 


THE PHYSICAL GEOGRAPHY OF THE SEA. 


oartaz water may be traced by the eye. Often one half of the 
a 


—_ 


Galtnewa, 


2 
3 
3 


Co are 


a) 


4 


r 
o 


vessel may be perceived floating in Gulf Stream water, 
while the other half is in common water of the sea; so 
sharp is the line, and such the want of affinity between 
those waters, and such, too, the reluctance, so to speak, 
on the part of those of the Gulf Stream to mingle with 
the common water of the sea. 

At the salt-works in France, and along the shores 
of the Adriatic, where the “salines” are carried on by 
the process of solar evaporation, there is a series of vats 
or pools through which the water is passed as it comes 
from the sea, and is reduced to the briny state. The 
longer it is exposed to evaporation the salter it grows, 
and the deeper is the hue of its blue, until crystallization 
is about to commence, when the now deep blue water 
puts on a reddish tint. Now the waters of the Gulf 
Stream are salter’ than the waters of the sea through 
which they flow, and hence we can account for the deep 
indigo blue which all navigators observe off the Carolina 
coasts. 

These salt-makers are in the habit of judging of 
the richness of the sea water in salt by its colour—the 
greener the hue, the fresher the water. We have in this, 
_ perhaps, an explanation of the contrasts which the waters 
of the Gulf Stream present with-those of the Atlantic, as 
well as of the light green of the North Sea and other 
Polar waters; also of the dark blue of the trade-wind 
regions, and especially of the Indian Ocean, which poets 
have described as the “black waters.” 

What is the cause of the Gulf Stream has always 
puzzled philosophers. Many are the theories and numer- 


THE GULF STREAM. 3 


ous the speculations that have been advanced with regard 
to it. Modern investigations and examinations are be- 
ginning to throw some light upon the subject, though all 
is not yet clear. 

Early writers maintained that the Mississippi River 
was the father of the Gulf Stream. Its floods, they said, 
produce it; for its velocity, it was held, could be com- 
puted by the rate of the current of the river. 

Captain Livingston overturned this hypothesis by show- 
ing that the volume of water which the Mississippi River 
empties into the Gulf of Mexico is not equal to the three- 
thousandth part of that which escapes from it through 
the Gulf Stream. 

Moreover, the water of the Gulf Stream is salt—that 
of the Mississippi fresh; and those philosophers’ forgot 
that just as much salt as escapes from the Gulf of Mexico 
through this stream, must enter the Gulf through some 
other channel from the main ocean ; for, if it did not, the 
Gulf of Mexico, in process of time, unless it had a salt 
bed at the bottom, or was fed with salt springs from 
below—neither of which is probable—would become a 
fresh water basin. 

The above quoted argument of Captain Livingston, 
however, was held to be conclusive ; and upon the remains 
of the hypothesis which he had so completely overturned 
he set up another, which, in turn, has been upset. In it 
he ascribed the velocity of the Gulf Stream as depending 
“on the motion of the sun in the ecliptic, and the influ- 
ence he has on the waters of the Atlantic.” 


eet 


Theories 
as to its 
cause. 


$6 


Captain 
Livingston 


But the opinion that came to be the most generally § 7 


received and deep rooted in the mind of seafaring people 


CHAPTER 
I. 


Dr. Frank- 
lin's opin- 
ion about 

the trade- 
winds. 


Not con- 
clusive. 


38 


Strait of 
Eonifaccio 


{ts differ- 
ence from 
the Gulf 


Stream. 


4 THE PHYSICAL GEOGRAPHY OF THE SEA. 


was the one repeated by Dr. Franklin, and which held 
that the Gulf Stream is the escaping of the waters that 
have been forced into the Caribbean Sea by the trade- 
winds, and that it is the pressure of those winds upon 
the water which forces up into that sea a head, as it 
were, for this stream. 

We know of instances in which waters have been ac- 
cumulated on one side of a lake, or in one end of a canal, 
at the expense of the other. The pressure of the trade- 
winds may assist to give the Gulf Stream its initial 
velocity, but are they of themselves adequate to such an 
effect? Too my mind, the laws of Hydrostatics, as at 
present expounded, appear by no means to warrant the 
conclusion that it is, unless the aid of other agents also 
be brought to bear. 

Admiral Smyth, in his valuable memoir on the Medi- 
terranean (p. 162), mentions that a continuance in the 
Sea of Tuscany of “gusty gales” from the south-west 
has been known to raise its surface no less than twelve 
feet above its ordinary level. This, he says, occasions a 
strong surface drift through the Strait of Bonifaccio. But 
in this we have nothing like the Gulf Stream; no deep 
and narrow channel-way to conduct these waters off like 
a miniature river even in that sea, but a mere surface 
fiow, such as usually follows the piling up of water in 
any pond or gulf above the ordinary level. The Boni- 
faccio current does not flow like a “river in the sea” 
across the Mediterranean, but it spreads itself out as soon 
as it passes the Straits, and, like a circle on the water, 
loses itself by broad spreading as soon as it finds sea- 
room, 


THE GULF STREAM. 5 


Supposing the pressure of the waters that are forced 
into the Caribbean Sea by the trade-winds to be the sole 
cause of the Gulf Stream, that Sea and the Mexican Gulf 
should have a much higher level than the Atlantic. 
Accordingly, the advocates of this theory require for its 
support “a great degree of elevation.” Major Rennell 
likens the stream to “an immense river descending from 
a higher level into a plain.” Now, we know very nearly 
the average breadth and velocity of the Gulf Stream in 
the Florida Pass. We also know, with a like degree of 
approximation, the velocity and breadth of the same 
waters off Cape Hatteras. Their breadth here is about 
seventy-five miles against thirty-two in the “ Narrows” 
of the Straits, and their mean velocity is three knots off 
Hatteras against four in the “Narrows.” This being the 
case, it is easy to show that the depth of the Gulf Stream 
off Hatteras is not so great as it is in the “ Narrows” of 
Gemini by nearly 50 per cent., and that, consequently, 
instead of descending, its bed represents the surface of 
an inclined plane, with its descent inclined from the north 
toward the south, wp which plane the lower depths of 
the stream must ascend. If we assume its depth off 
Bemini* to be two hundred fathoms, which are thought 
to be within limits, the above rates of breadth and velo- 
city will give one hundred and fourteen fathoms for its 
depth off Hatteras. The waters, therefore, which in the 
Straits are below the level of the Hatteras depth, so far 
from descending, are actually forced up an inclined plane, 


* Professor Bache reports that the officers of the Coast Survey have sounded 


with the deep sea lead, and ascertained its depth here to be 370 fathoms (Janu- 
ary, 1856), 


CHAPTER 


Breadth 
and veio- 
city in the 
Florida 
Pass. 


Off Cape 
Hatteraa 


Its depth 
off Bemini 


Its watera 
ascend 


6 THE PHYSICAL GEOGRAPHY OF THE SEA, 


onarren Whose submarine ascent is not less than ten inches to the 


§ 10 


The Nia- 
fara con- 
trasted 
with the 
Gulf 
Stream. 


$11 


Currents 
meeting 
St. 


mile. 

The Niagara is an “immense river descending into 
a plain.” But instead of preserving its characler in 
Lake Ontario as a distinct and well-defined stream for 
several hundred miles, it spreads itself out, and its waters 
are immediately lost in those of the lake. Why should 
not the Gulf Stream do the same? It gradually enlarges 
itself, it is true; but, instead of mingling with the ocean 
by broad spreading, as the “immense rivers” descending 
into the northern lakes do, its waters, like a stream of oil 
in the ocean, preserve a distinctive character for more 
than three thousand miles. 

Moreover, while the Gulf Stream is running to the 
north from its supposed elevated level at the south, 
there is a cold current coming down from the north ; 
meeting the warm waters of the Gulf midway the ocean, 
it divides itself, and runs by the side of them right back 
into those very reservoirs at the south, to which theory 
gives an elevation sufficient to send out entirely across 
the Atlantic a jet of warm water said to be more than three 
thousand times greater in volume than the Mississippi River, 
This current from Baffin’s Bay has not only no trade- 
winds to give it a head, but the prevailing winds are 
unfavourable to it, and for a great part of the way it is 
below the surface, and far beyond the propelling reach of 
any wind. And there is every reason to believe that 
this, with other polar currents, is quite equal in volume 
to the Gulf Stream. Are they not the effects of like 
causes? If so, what have the trade winds to do with 
the one more than the other ? 


THE GULF STREAM, ff 


It is a custom often practised by seafaring people 
to throw a bottle overboard, with a paper, stating the 


{ime and place at which it is done. In the absence of § 


other information as to currents, that afforded by these 
mute little navigators is of great value. They leave no 
tracks behind them, it is true, and their routes can not 
be ascertained. But knowing where they were cast, and 
seeing where they are found, some idea may be formed 
as to their course. Straight lines may at least be drawn, 
showing the shortest distance from the beginning to the 
end of their voyage, with the time elapsed. Admiral 
Beechey, R.N., has prepared a chart, representing, in this 
way, the tracks of more than one hundred bottles. From 
it, it appears that the waters from every quarter of the 
Atlantic tend toward the Gulf of Mexico and its stream. 
Bottles cast into the sea midway between the Old and 
the New Worlds, near the coasts of Europe, Africa, and 
America, at the extreme north or farthest south, have 
been found either in the West Indies, or the British 
Isles, or within the well-known range of Gulf Stream 
waters. 

Of two cast out together in south latitude on the coast 
of Africa, one was fotind on the island of Trinidad; the 
other on Guernsey, in the English Channel. In the ab- 
sence of positive information on the subject, the circum- 
stantial evidence that the latter performed the tour of 
the Gulf is all but conclusive. And there is reason to 
suppose that some of the bottles of the admiral’s chart 
have also performed the tour of the Gulf Stream ; then, 
without being cast ashore, have returned with the drift 
along the coast of Africa into the inter-tropical region ; 


CHAPTER 


Informa- 
tion de- 
rived from 
bottles. 


Admiral 
Beechey's 
cher: 


8 THE PHYSICAL GEOGRAPHY OF THE SEA. 


ouarter thence through the Caribbean Sea, and so on with the 
Gulf Stream again. (Plate VI.) 

Another bottle, thrown over off Cape Horn by an 
American master, in 1837, has been recently picked up 
on the coast of Ireland. An inspection of the chart, and 
of the drift of the other bottles, seems to force the con- 
clusion, that this bottle too went even from that remote 
region to the so-called higher level of the Gulf Stream 
reservoir. 

§13 Midway the Atlantic, in the triangular space between 
the Azores, Canaries, and the Cape de Verd Islands, 

Sargasso is the Sargasso Sea. (Plate VI.) Covering an area 
equal in extent to the Mississippi Valley, it is so thickly 
matted over with Gulf Weeds (fucus natuns), that the 

speed of vessels passing through it is often much retarded. 

When the companions of Columbus saw it, they thought, 

it marked the limits of navigation, and became alarmed. 

To the eye, at a little distance, it seems substantial enough 

to walk upon. Patches of the weed are always to be 

seen floating along the outer edge of the Gulf Stream. 

Now, if bits of cork or chaff, or any floating substance, 

be put into a basin, and a circular motion be given to 

to the water, all the light substances will be found 
crowding together near the centre of the pool, where 
there is the least motion. Just such a basin is the 

Atlantic Ocean to the Gulf Stream; and the Sargasso 

ae Sea is the centre of the whirl Columbus first found 
Columbus this weedy sea in his voyage of discovery; there it has 
remained to this day, moving up and down, and changing 
its position like the calms of Cancer, according to the 
seasons, the storms, and the winds. Exact observations 


THE GULF STREAM. 9 


as to its limits and their range, extending back for fifty 
years, assure us that its mean position has not been 
altered since that time. This indication of a circular 
motion by the Gulf Stream is corroborated by the bottle 
chart, by Plate VI., and other sources of information. If, 
therefore, this be so, why give the endless current a higher 
level in one part of its course than another ? 

Nay, more ; at the very season of the year when 
the Gulf Stream is rushing in greatest volume through 
the Straits of Florida, and hastening to the north with 
the greatest rapidity, there is a cold stream from Baftin’s 
Bay, Labrador, and the coasts of the north, running to 
the south with equal velocity. Where is the trade-wind 
that gives the higher level to Baffin’s Bay, or that even 
presses upon, or assists to put this current in motion ? 
The agency of winds in producing currents in the deep 
sea must be very partial. These two currents meet off 
the Grand Banks, where the latter is divided. One part 
of it underruns the Gulf Stream, as is shown by the ice- 
bergs, which are carried in a direction tending across its 
course. The probability is, that this “fork” flows on 
toward the south, and runs into the Caribbean Sea, for 
the temperature of the water at a little depth there kas 
been found far below the mean temperature of the earth’s 
crust, and quite as cold as at a corresponding depth off 
the Arctic shores of Spitzbergen. 

More water can not run from the equator or the 
pole than to it. If we make the trade-winds to cause 
the Gulf Stream, we ought to have some other wind to 
produce the Polar flow; but these currents, for the most 
part, and for great distances, are submarine, and there- 


CHAPTEL 
I. 


Its limits 
and posi- 
tion. 


14 


wn 


Cold 
stream 
from 
Baffie:'a 
Bay. 


Its direo 
tion. 


§ 15 


Currents 
not influ- 
enced by 
winds. 


CHAPTER 
I. 


— 


§ 16 


Resistance 
to the Gult 
Stream. 


§17 


10 THE PHYSICAL GEOGRAPHY OF THE SEA. 


fore beyond the influence of winds. Hence it should 
appear that winds have little to do with the general 
system of aqueous circulation in the ocean. 

The other “fork” runs between us and the Gulf 
Stream to the south, as already described. As far as it 
has been traced, it warrants the belief that it, too, runs 
up to seek the so-called higher level of the Mexican Gulf. . 

The power necessary to overcome the resistance 
opposed to such a body of water as that of the Gulf 
Stream, running several thousand miles without any 
renewal of impulse from the forces of gravitation or any 
other known cause, is truly surprising. It so happens 
that we have an argument for determining, with consi- 
derable accuracy, the resistance which the waters of this 
stream meet with in their motion toward the east. Owing 
to the diurnal rotation, they are carried around with the 
earth on its axis toward the east with an hourly velocity 
ot one hundred and fifty-seven* miles greater when they 
enter the Atlantic than when they arrive off the Banks 
of Newfoundland ; for, in consequence of the difference 
of latitude between the parallels of these two places, their 
rate of motion around the axis of the earth is reduced 
from nine bundred and fifteen+ to seven hundred and 
fifty-eight miles the hour. 

Therefore this immense volume of water would, if 
Wwe suppose it to pass from the Bahamas to the Grand 
Banks in an hour, meet with an opposing force in the 


* In this calculation the earth is treated as a perfect sphere, with a diameter 
of 7925°56 miles. 

+ Or 915°26 to 758°60. On the latter parallel, the current has an east set of 
about one and a half miles the hour, making the true velocity to the east ; and 
on the axis of the earth, about seven hundred and sixty miles an hour at the 
Grand Banks. 


THE GULF STREAM. ia 


shape of resistance sufficient, in the aggregate, to retard 
it two miles and a half the minute in its eastwardly rate. 
If the actual resistance be calculated according to received 
laws, it will be found equal to several atmospheres. And 
by analogy, how inadequate must the pressure of the 
gentle trade-winds be to such resistance, and to the effect 
assigned them? If, therefore, in the proposed inquiry, 
we search for a propelling power nowhere but in the 
higher level of the Gulf, we must admit, in the head of 
water there, the existence of a force capable of putting in 
motion, and of driving over a plain at the rate of four 
miles the hour, all the waters, as fast as they can be 
brought down by three thousand’ such streams as the 
Mississippi River, 


a power at least sufficient to over- 
come the resistance required to reduce from two miles 
and a half to a few feet per minute the velocity of a 
stream that keeps in perpetual motion one fourth of all 
the waters in the Atlantic Ocean. 

The facts, from observation on this interesting sub- 
ject, afford us at best but a mere glimmer of light, by 
no means sufficient to make any mind clear as to a 
higher level of the Gulf, or as to the sufficiency of any 
other of the causes generally assigned for this wonderful 
stream. If it be necessary to resort to a higher level in 
the Gulf to account for the velocity off Hatteras, I cannot 
perceive why we should not, with like reasoning, resort 
to a higher level off Hatteras also to account for the velo- 
city off the Grand Banks, and thus make the Gulf Stream, 
throughout its circuit, a descending current, and, by the 
reductio ad absurdum, show that the trade-winds are 
not adequate to the effect ascribed. Moreover, the top 


1 86, 


CHAPTER 
I. 


_— 


§ 18 


No cer- 
tainty as 
to the 
cause of 
the Gulf 
Stream. 


ie THE PHYSICAL GEOGRAPHY OF THE SEA. 


cuartzr Of the Guif Stream runs on a level with the ccean, there- 


§ 19 


Hvypothe- 


&15s. 


§ 20 


§ 21 


fore we know it is not a descending current. 

When facts are wanting, it often happens that hypo- 
thesis will serve, in their stead, the purposes of ilus- 
tration. Let us, therefore, suppose a globe of the earth’s 
size, having a solid nucleus, and covered ail over 
with water two hundred fathoms deep, and that every 
source of heat and cause of radiation be removed, so 
that its fluid temperature becomes constant and uniform 
throughout. On such a globe, the equilibrium remain- 
ing undisturbed, there would be neither wind nor cur- 
rent. 

Let us now suppose that all the water within the 
tropics, to the depth of one hundred fathoms, suddenly 
becomes oil. The aqueous equilibrium of the planet 
would thereby be disturbed, and a general system of cur- 
rents and counter currents would be immediately com- 
menced—the oil, in an unbroken sheet on the surface, 
running toward the poles, and the water, in an under 
current, toward the equator. The oil is supposed, as it 
reaches the polar basin, to be reconverted into water, and 
the water to become oil as it crosses Cancer and Capri- 
corn, rising to the surface in the intertropical regions, and 
returning as before. 

Thus, without wind, we should have a perpetual and 
uniform system of tropical and polar currents. In con- 
sequence of diurnal rotation of the planet on its axis, 
each particle of oil, were resistance small, would approach 
the poles on a spiral turning to the east, with a relative 
velocity greater and greater, until finally it would reach 
the pole, and whirl about it at the rate of nearly a thou- 


THE GULF STREAM. 13 


gand miles the hour. Becoming water and losing its cnaprea 
velocity, it would approach the tropics by a similar but kits 
inverted spiral, turning toward the west. Owing to the 
principle here alluded to, all currents from the equator to 

the poles should have an eastward tendency, and all from 

the poles toward the equator a westward. 

Let us now suppose the solid nucleus of this hypo- § 22 
thetical globe to assume the exact form and shape of the 
bottom of our seas, and in all respects, as to figure and 
size, to represent the shoals and islands of the sea, as well 
as the coast lines and continents of the earth. The 
uniform system of currents just described would now be Sarees 
interrupted by obstructions and local causes of various 
kinds, such as unequal depth of water, contour of shore- 
lines, &c. ; and we should have at certain places currents 
greater in volume and velocity than at others. But still 
there would be a system of currents and counter currents 
to and from either pole and the equator. Now, do not 
the cold waters of the north, and the warm waters of the 
Gulf, made specifically lighter by tropical heat, and which 
we see actually preserving such a system of counter cur- 
rents, hold, at least in some degree, the relation of the 
supposed water and oil? 

In obedience to the laws here hinted at, there is a § 23 
constant tendency'of polar waters toward the tropics, and Tendency 


of tropical waters toward the poles. Captain Wilkes, of Sat 
the United States Exploring Expedition, crossed one of kas 
these hyperborean under-currents two hundred miles in 
breadth at the equator. 

Assuming the maximum velocity of the Gulf Stream § 24 


at five knots, and its depth and breadth in the Narrows cata 


1 Plate IX. 


CHAPTER 


—— 


Difference 
of specific 
gravity. 


§ 25 


Author's 
opinion. 


14 THE PHYSICAL GEOGRAPHY OF THE SEA. 


of Bemini as before, the vertical section across would 
present an area of two hundred millions of square feet 
moving at the rate of seven feet three inches per second. 
The difference of specific gravity between the volume 
of Gulf water that crosses this sectional line in one 
second, and an equal volume of water at the ocean 
temperature of the latitude, supposing the two volumes 
to be equally salt, is fifteen millions of pounds. If 
these estimated dimensions (assumed merely for the pur- 
poses of illustration) be within limits, then the force per 
second operating here to propel the waters of the Gulf 
toward the pole is the equilibrating tendency due to 
fifteen millions of pounds of water in the latitude of 
Bemini. This is in one scale of the balance. In the 
other, the polar scale, there is the difference of specific 
gravity due an equal volume of water in the polar basin, 
on account of its degree of temperature as well as of salt- 
ness. 

In investigating the currents of the seas, such agencies 
should be taken into account. As a cause, I doubt 
whether this one is sufficient of itself to produce a 
stream of such velocity and compactness as that of the 
Gulf; for, assuming its estimated discharge to be correct, 
the proposition is almost susceptible of mathematical de- 
monstration, that to overcome the resistance opposed in 
consequence of its velocity would require a force at least 
sufficient to drive, at the rate of three miles the hour, 
ninety thousand millions of tons up an inelined plane 
having an ascent of three inches to the mile.* Yet heat, 
the very principle from which one of these agents is de- 


ee 


* Supposing there be no resistance from frictiva. 
25 '9: 


THE GULF STREAM. 15 


rived, is admitted to be one of the chief causes of those cuaprza 
. . . 5 I. 
winds which are said to be the sole cause of this current. — 
The chemical properties, or, if the expression be admis- § 26 
sible, the galvanic properties of the Gulf Stream waters, Chemical 
: E . properties 
as they come from their fountains, are different, or rather °f its 


more intense, than they are in sea water generally. If ine 
so, they may have a peculiar molecular arrangement or 
viscosity that resists the admixture of other sea waters 
differing in temperature and saltness. It is a well known 

fact, that waters of different temperatures, when put in 

the same vessel, do not readily mix of themselves, but 
require the process of agitation. Nor do large volumes 

of water in motion readily admit of the admixture of 
water at rest. 

In 1843 the Secretary of the Navy took measures for Expert- 
procuring a series of observations and experiments with ee 
regard to the corrosive effects of sea water upon the cop- 
per sheathing of ships. With patience, care, and labour, 
these researches were carried on for a period of ten years; 
and it is said the fact has been established, that the cop- 
per on the bottom of ships cruising in the Caribbean Sea 
and Gulf of Mexico suffers more from the action of sea 
water upon it, than does the copper of ships cruising in 
any other part of the ocean. In other words, the salts Vata 
of these waters create the most powerful galvanic battery 
that is found in the ocean. 

Now, it may be supposed—other things being equal § 27 
—that the strength of this galvanic battery in the sea 
depends in some measure upon the proportion of salts 
that the sea waters hold in solution, and also upon tem- 
jera ture. 


CHAPTER 


§ 28 


Chemical 
affinities, 


§ 29 


Dr. Tho- 
massy’8 
experi- 
ments, 


§ 30 


16 THE PHYSICAL GEOGRAPHY OF THE SEA, 


If, therefore, in the absence of better information, 
this suggestion be taken as a probability as to the origin 
of these galvanic properties, we may go a step farther, 
and draw the inference that the waters of the Gulf 
Stream, as they rush out in such volume and with such 
velocity into the Atlantic, have not only chemical afiini- 
ties peculiar to themselves, but, having more salts, higher 
temperature, and a high velocity, they are not so per- 
meable to water differing from them in all these respects, 
and, consequently, the line of meeting between them and 
the other water of the ocean becomes marked. This is 
the case with almost all waters in rapid motion. Where | 
the Mississippi and Missouri rivers come together, there 
is a similar reluctance on the part of their waters to mingle, 
for the line of meeting between them can be traced for 
miles below the junction of the two rivers. 

The story told by the copper’ and the blue colour’ 
indicates a higher point of saturation with salts than 
sea water generally, and the salometer confirms it. Dr. 
Thomassy, a French savant, who has been extensively 
engaged in the manufacture of salt by solar evapora- 
tion, informs me that on his passage to the United 
States he tried the saltness of the water with a most 
delicate instrument: he found it in the Bay of Biscay to 
contain 34 per cent. of salt; in the trade-wind region, 
4s per cent. ; and in the Gulf Stream, off Charleston, 4 
per cent., notwithstanding the Amazon and the Missis- 
sippi, with all the intermediate rivers, and the clouds of 
the West Indies, had lent their fresh water to dilute the 
saltness of this basin. 

Now, the question may be asked, What should make 


1 2 26. 7§3 


THE GULF STREAM. 17 


the waters of the Mexican Gulf and Caribbean Sea salter cuapren 
than the waters of like temperature in those parts of the —_ 
ocean through which the Gulf Stream flows ? 

There are physical agents that are known to be at work g 31 
in different parts of the ocean, the tendency of which physica 
is to make the waters in one part of the ocean salter “~~ 
and heavier, and in another part lighter and less salt 
than the average of sea water. These agents are those 
employed by sea-shells in secreting solid matter for their 
structures ; they are also heat* and radiation, evaporation 
and precipitation. 

In the trade-wind regions at sea,’ evaporation is gener- § 32 
ally in excess of precipitation, while in the extra-tropical vapors 
regions the reverse is the case; that is, the clouds let Ps 
down more water there than the winds take up again ; 
and these are the regions in which the Gulf Stream 
enters the Atlantic. 

Along the shores of India, where experiments have been § 33 
carefully made, the evaporation from the sea amounts 
to three-fourths of an inch daily. Suppose it in the trade- 
wind region of the Atlantic to amount to only half an 
inch, that would give an annual evaporation of fifteen 
feet. In the process of evaporation from the sea, fresh 
water only is taken up, the salts are left behind. 

Now, a layer of sea water fifteen feet deep, and as 
broad as the trade-wind belts of the Atlantic, and reach- 

- ing across the ocean, contains an immense amount of salts. 

The great equatorial current (Plate VI.) which sweeps § 34 
from the shores of Africa across the Atlantic into the 
Caribbean Sea is a surface current; and may it not bear 


* According to Dr. Marcet, sea water contracts down to 28°, 
1 Plate VIII. 
2 


18 THE PHYSICAL GEOGRAPHY OF THE SEA. 


cnapTeR into that sea a large portion of those waters that have 


satisfied the thirsty trade-winds with saltless vapour? 


Reason for Tf so—and it probably does—have we not detected here 


saltness of 


Garithese the foot-prints of an agent that does tend to make the 
ea, 


Effects of 


avapora- 


tion. 


waters of the Caribbean Sea salter, and therefore heavier 
than the average of sea water at a given temperature ? 

It is immaterial, so far as the correctness of the prin- 
ciple upon which this reasoning depends is concerned, 
whether the annual evaporation from the trade-wind 
regions of the Atlantic be fifteen, ten, or five feet. The 
layer of water, whatever be its thickness, that is evapo- 
rated from this part of the ocean, is not all poured back 
by the clouds in the same place whence it came. But 
they take it and pour it down in showers upon the extra- 
tropical regions of the earth—on the land as well as in 
the sea—and on the land more water is let down than 
is taken up into the clouds again. The rest sinks down 
through the soil to feed the springs, and return through 
the rivers to the sea. Suppose the excess of precipi- 
tation in these extra-tropical regions of the sea to amount 
to but twelve inches, or even to but two—it is twelve 
inches or two inches, as the case may be, of fresh water 
added to the sea in those parts, and which therefore tends 
to lessen the specific gravity of sea water there to that 
extent, and to produce a double effect, for the simple 
reason that what is taken from one scale, by being put 
into the other, doubles the difference. 

Now that we may form some idea as to the influ- 
ence which the salts left by the vapour that the trade- 
winds, north-east and south-east, take up from sea water, 
is calculated to exert in creating currents, let us make a 


THE GULF STREAM. 19 


partial calculation to show how much salt this vapour held cuaprzr 
in solution before it was taken up, and, of course, while mate 
it was yet in the state of sea water. The north-east 
trade-wind regions of the Atlantic embrace an area of at 

least three million square miles; and the yearly evapora- supposed 


6 bio : ; evapora- 

tion from it is* we will suppose, fifteen feet. The salt tion inthe 
. : : . trade-wind 

that is contained in a mass of sea water covering to regions, 


the depth of fifteen feet an area of three million square 
miles in superficial extent, would be sufficient to cover 
the British islands to the depth of fourteen feet. As this 
water supplies the trade-winds with vapour, it therefore 
becomes salter, and as it becomes salter the forces of 
aggregation among its particles are increased, as we may 
infer from the fact? that the waters of the Gulf Stream 
are reluctant to mix with those of the ocean. 

Whatever be the cause that enables these trade-wind § 36 
waters to remain on the surface, whether it be from Sea 
the fact just stated, and in consequence of which the evap 
waters of the Gulf Stream are held together in their current 
channel ; or whether it be from the fact that the expan- 
sion from the heat of the torrid zone is sufficient to 
compensate for this increased saltness; or whether it be 
from the low temperature and high saturation of the 
submarine waters of the inter-tropical ocean ; or whether 
it be owing to all of these influences together that these 
waters are kept on the surface, suffice it to say, we 
do know that they go into the Caribbean Sea’ as a 
surface current. On their passage to and through it, 
they intermingle with the fresh waters that are emptied 
into the sea from the Amazon, the Oronoco, and the 
Mississippi, and from the clouds, and the rivers of the 


1 § 33. dS 20 3 § 34. 


20 THE PHYSICAL GEOGRAPHY OF THE SEA. 


cuaPTeR coasts round about. An immense volume of fresh water 
Beg supplied from these sources. It tends to make the 
Peinte: bes water, that the trade-winds have been playing upon 
rie and driving along, less briny, warmer, and lighter; for 


the waters of these large inter-tropical streams are warmer 
than sea water. This admixture of fresh water still leaves 
the Gulf Stream a brine stronger than that of the extra- 
tropical sea generally, but not quite so strong as that of 
the trade-wind regions.’ 

Bestel It is safe to assume that the trade-winds, by their 

wind. constant force, do assist to skim the Atlantic of the water 
that has supplied them with vapour, driving it into the 
Caribbean Sea, whence, for causes unknown, it escapes 
by the channel of the Gulf Stream in preference to any 
other.* 

§37 In the present state of our knowledge concerning 
this wonderful phenomenon—for the Gulf Stream is one 
of the most marvellous things in the ocean—we can do 
little more than conjecture. But we have two causes in 
operation which we may safely assume are among those 

Saltness of concerned in producing the Gulf Stream. One of these 


Balticand . , F ‘ 
North is in the increased saltness of its water after the trade- 


a winds have been supplied with vapour from it, be it much 
or little; and the other is in the diminished quantum of 
salt which the Baltic and the Northern Seas contain. 
The waters of the Baltic are nearly fresh ; they are said 
to contain only about half as much salt as sea water does 
generally. 


338 Now here we have, on one side, the Caribbean Sea 


* The tact is familiar to all concerned in the manufacture of salt by solar eva- 
poration, ui at the first show of crystallization commences at the surface, 


1 § 29, 


THE GULF STREAM. 21 


and Gulf of Mexico, with their waters of brine; on the cuaprsa 
other, the great Polar basin, the Baltic and the North —~— 
Sea, the two latter with waters that are but little more 

than brackish.+ In one set of these sea-basins the water 

is heavy; in the other it is light. Between them the 

ocean intervenes; but water is bound to seek and to 
maintain its level; and here, therefore, we unmask one One agent 


concerned 


of the agents concerned in causing the Gulf Stream. in causing 
What is the influence of this agent—that is, how great penne 
is it, and to what extent does it go—we can not say; only 

it is at least one of the agents concerned. Moreover, 
speculate as we may as to all the agencies concerned in 
collecting these waters, that have supplied the trade- 
winds with vapour, into the Caribbean Sea, and then in 
driving them across the Atlantic—of this we may be 

sure, that the salt which the trade-wind vapour leaves 
behind in the tropics has to be conveyed away from the 
trade-wind region, to be mixed up again in due propor- 

tion with the other water of the sea—the Baltic Sea and 

the Arctic Ocean included—and that these are some of 

the waters at least which we see running off through the 

Gulf Stream. To convey them away is doubtless one of 

the offices which, in the economy of the ocean, has been 
assigned to it. 


As to the temperature of the Gulf Stream, there is, in tempera 
a winter’s day, off Hatteras, and even as high up as the ™* 
Grand Banks of Newfoundland in mid ocean, a difference 


+ The Polar basin has a known water area of 3,000,000 square miles, and an 
unexplored area, including land and water, of 1,500,000 square miles. Whether 
the water in this basin be more or less salt than that of the inter-tropical seas, 
we know it is quite different in temperature, and difference of temperature will 
beget currents quite as readily as difference in saltness, for change in specific 
gravity follows either. 


bo 


2 THE PHYSICAL GEOGRAPHY OF THE SEA. 


cRAPTER between its waters and those of the ocean near by of 20°, 
I. 


—_ 


§ 39 


and even 30°. Water, we know, expands by heat, and 
here the difference of temperature may more than com- 
pensate for the difference in saltness, and leave, therefore, 
the waters of the Gulf Stream lighter by reason of their 
warmth. 

If they be lighter, they should therefore occupy a 
higher level than those through which they flow. As- 
suming the depth off Hatteras to be one hundred and 


Expansion fourteen fathoms, and allowing the usual rates of expan- 


§ 40 


Surface 
current. 


sion for sea water, figures show that the middle or axis of 
the Gulf Stream there should be nearly two feet higher 
than the contiguous waters of the Atlantic. Hence the 
surface of the stream should present a double inclined 
plane, from which the water would be running down on 
either side as from the roof of a house. As this runs off 
at the top, the same weight of colder water runs in at the 
bottom, and so raises up the cold water bed of the Gulf 
Stream, and causes it to become shallower and shallower 
as it goes north. That the Gulf Stream is therefore roof- 
shaped, causing the waters on its surface to flow off to 
either side from the middle, we have not only circum- 
stantial evidence to show, but observations to prove. 
Navigators, while drifting along with the Gulf Stream, 
have lowered a boat to try the surface current. In 
such cases, the boat would drift either to the east or 
to the west, as it happened to be on one side or the other 
of the axis of the stream, while the vessel herself would 
drift along with the stream in the direction of its course ; 
thus showing the existence of a shallow roof-current from 
the middle toward either edge, which would carry the 


THE GULF STREAM. 723) 


boat along, but which, being superficial, does not extend cuapres 
deep enough to affect the drift of the vessel. = 

That such is the case’ is also indicated by the cireum- § 41 
stance that the sea-weed and drift-wood which are found 
in such large quantities along the outer edge’ of the 
Gulf Stream, are never, even with the prevalence of 
easterly winds, found along its inner edge—and for the 
simple reason that to cross the Gulf Stream, and to 
pass over from that side to this, they would have 
to drift up an inclined plane, as it were; that is, they Diredtion 
would have to stem this roof-current until they reached woog, &e 
the middle of the stream. We rarely hear of planks, or 
wrecks, or of any floating substance which is cast into 
the sea on the other side of the Gulf Stream being found 
along the coast of the United States. Drift-wood, trees, 
and seeds from the West India islands, are said to have 
been cast up on the shores of Europe, but never, that I 
ever heard, on the Atlantic shores of this country. 

We are treating now of the effects of physical causes, 
The question to which I ask attention is, Why does the Causes of 


the direc- 
Gulf Stream slough off and cast upon its outer edge, sea- tion of 


weed, drift-wood, and all other solid bodies that are found acta 
floating upon it? 
One cause has been shown to be in its roof-shaped g 42 
current ; but there is another which tends to produce the 
same effect ; and because it is a physical agent, it should 
not, in a treatise of this kind, be overlooked, be its action 
never so slight. I allude now to the effects produced 
upon the drift matter of the stream by the diurnal rota- 
tion of the earth. 
Take, for illustration, a railroad that runs north and § 43 


1 § 39, anes, 


24 THE PHYSICAL GEOGRAPHY OF THE SEA. 


czapter south. It is well known to engineers that when the cars 
tare going north on such a road, their tendency is to 
run off on the east side; but when the train is going 
south, their tendency is to run off on the west side of 
the track—i. e., always on the right-hand side in our 
niustras hemisphere. Whether the road be one mile or one hun- 
‘is dred miles in length, the effect of diurnal rotation is the 
same, and the tendency to run off, as you cross a given 
parallel at a stated rate of speed, is the same; whether 
the road be long or short, the tendency to fly off the 
track being in proportion to the speed of the trains, and 
not at all in proportion to the length of the road. 
§44 Now, vis imertic and velocity being taken into the 
Diurnal account, the tendency to obey the force of this diurnal 
i rotation, and to trend to the right, is proportionably as 
oreat in the case of a patch of sea-weed as it drifts along 
the Gulf Stream, as it is in the case of the train of cars 
as they speed to the north along the iron track of the 
Hudson River railway, or any other railway that les 
north and south. The rails restrain the cars and prevent 
them from flying off;- but there are no rails to restrain 
the sea-weed, and nothing to prevent the drift-matter of 
the Gulf Stream from going off in obedience to this 
force. The slightest impulse tending to turn aside bodies 
moving freely in water is immediately felt and implicitly 
obeyed. 
g45 It is in consequence of this diurnal rotation that 
drift-wood coming down the Mississippi is so very apt 
to be cast upon the west or right bank. This is the 
reverse of what obtains upon the Gulf Stream, for it 
flows to the north ; it therefore sloughs off'to the east. 


1 § 43. 


THE GULF STREAM. 25 


The effect of diurnal rotation upon the winds and cuarrer 
upon the currents of the sea is admitted by all—the she 


. . . ° . ° Its effects 
trade-winds derive their easting from it—it must, there- onthe 


fore, extend to all the matter which these currents bear ii i 
with them, to the largest iceberg as well as to the merest 
spire of grass that floats upon the waters, or the minut- 
est organism that the most powerful microscope can 
detect among the impalpable particles of sea-dust. This 
effect of diurnal rotation upon drift will be frequently 
alluded to in the pages of this work. 

In its course to the north, the Gulf Stream gradually g 4¢ 
trends more and more to the eastward, until it arrives 
off the Banks of Newfoundland, where its course becomes 
nearly due east. These banks, it has been thought, Bee 
deflect it from its proper course, and cause it to take this lana 
turn. Examination will prove, I think, that they are 
an effect, certainly not the cause. It is here that the 
frigid current already spoken of, with its icebergs from 
the north, are met and melted by the warm waters 
of the Gulf. Of-course the loads of earth, stones, and 
gravel brought down upon them are here deposited. Cap- 
tain Scoresby, far away in the north, counted five hun- 
dred icebergs setting out from the same vicinity upon this 
cold current for the south. Many of therm, loaded with 
earth, have been seen aground on the Banks. This pro- 
cess of transferring deposits from the north for these 
shoals, and of snowing down upon them the infusoria 
and the corpses of “living creatures” that are spawned 
so abundantly in the warm waters of the Gulf Stream, 
and sloughed off in myriads for burial where the conflict 
between it and the great Polar current’ takes place, 


§11. a $14. 


CHAPTER 
I. 


—— 


Their 
formation. 


§ 47 


Course of 
the Gulf 
Stream. 


§ 48 


Diurnal 
rotation 
affects its 
course, 


26 THE PHYSICAL GEOGRAPHY OF THE SEA. 


is everlastingly going on. - These agencies, with time, 
seem altogether adequate to the formation of extensive 
bars or banks. 

The deep sea soundings that have been made by ves- 
sels of the navy’ tend to confirm this view as to the 
formation of these Banks. The greatest contrast in the 
bottom of the Atlantic is just to the south of these 
Banks. Nowhere in the open sea has the water been 
found to deepen so suddenly as here. Coming from the 
north, the bottom of the sea is shelving; but suddenly, 
after passing these Banks, its depth increases by almost a 
precipitous descent for many thousand feet, thus indicat- 
ing that the debris which forms the Grand Banks comes 
from the north. 

From the Straits of Bemini the course of the Gulf 
Stream (Plate VI.) describes (as far as it can be traced 
over toward the British Islands which are in the midst 
of its waters) the arc of a great circle as nearly as may 
be. Such a course as the Gulf Stream takes is very 
nearly the course that a cannon ball, could it be shot 
from these straits to those islands, would describe. 

If it were possible to see Ireland from Bemini, and to 
get a cannon that would reach that far, the person stand- 
ing on Bemini and taking aim, intending to shoot at 
Treland as a target, would, if the earth were at rest, sight 
direct, and make no allowance for difference of motion 
between marksman and target. 

But there is diurnal rotation ; the earth does re- 
volve on its axis; and since Bemini is nearer to the 
equator than Ireland is, the gun would be moving in 
diurnal rotation? faster than the target, and therefore 


1 Plate XI. 2 § 16. 


THE GULF STREAM. yTh 


the marksman, taking aim point blank at his target, 
would miss. He would find, on examination, that he 
had shot south—that is, to the right’ of his mark. In 
other words, that the path actually described by the 
ball would be the resultant of this difference in the rate 
of rotation and the trajectile force ; the former, impelling 
to the east, would cause the ball to describe a great circle, 
but one with too much obliquity to pass through the tar- 
get. Like a ray of light from the stars, the ball would 
be affected by aberration. 

It is the case of the passenger in the railroad car 
throwing an apple, as the train sweeps by, to a boy stand- 
ing by the wayside. If he throw straight at the boy, he 
will miss, for the apple, partaking of the motion of the 
cars, will go ahead of the boy, and for the very reason 
that the shot will pass in advance of the target, for both 
the marksman and the passenger are going faster than 
the object at which they aim. 

Hence we may assume it as a law, that the natural 
tendency of all currents in the sea, like the natural 
tendency of all projectiles through the air, is to describe 
their curves of flight in the planes of great circles. The 
natural tendency of all matter, when put in motion, is to 
go from point to point by the shortest distance, and it 
requires force to overcome this tendency. Light, heat, 
and electricity, running water, and all substances, whether 
ponderable or imponderable, seek, when in motion, to 
obey this law. Electricity may be turned aside from its 
course, and so may the cannon ball or running water ; 
but remove every obstruction, and leave the current or 
the shot free to continue on in the direction of the first 


CHAPTER 
I. 


——s 


§ 49 


Tilustra- 
tion. 


§ 50 


Natural 
tendency 
of currents 
to describe 
curves. 


28 THE PHYSICAL GEOGRAPHY OF THE SEA. 


cnapter impulse, or to turn aside of its own volition, so to speak, 
ae erand straight it will go, and continue to go—if on a 
plane, in a straight line; if on a sphere, in the are of a 
great circle—thus showing that it has no volition except 
to obey impulse, and the physical requirements to take 

the shortest way to its point of destination. 
-§51 The waters of the Gulf Stream, as they escape from 
the Gulf are bound for the British Islands, to the North 
inree of Sea, and Frozen Ocean.” Accordingly, they take,’ in 
Streamthe Obedience to this physical law, the most direct course 
San by which nature will permit them to reach their destina- 
oe tion. And this course, as already remarked, is nearly 
that of the great circle, and exactly that of the supposed 

cannon. ball. 

§52 Many philosophers have expressed the opinion—in- 
anes deed, the belief*is common among mariners—that the 
Shoals of coasts of the United States and the Shoals of Nantucket 
tnt turn the Gulf Stream toward the east; but if the 
eastward. 


view I have been endeavouring to make clear be 
correct 


and I think it is—it appears that the course 
of the Gulf Stream is fixed and prescribed by exactly 
the same laws that require the planets to revolve in 
orbits, the planes of which shall pass through the centre 
of the sun; and that, were the Nantucket Shoals not 
in existence, the course of the Gulf Stream, in the main, 
would be exactly as it is and where it is. The Gulf 
Stream is bound over to the North Sea and Bay of 
Biscay partly for the reason, perhaps, that the waters 
there are lighter than those of the Mexican Gulf ;’ and if 
the Shoals of Nantucket were not in existence, it could 
not pursue a more direct route. The Grand Banks, 


1 § 87, 2 Plate IX. 3 8 47, «$46, 5 § 37, 


THE GULF STREAM. 29 


‘and cold currents from the cuapres 


however, are encroaching, 
north come down upon it: they may, and probably do, pic 
assist now and then to turn it aside. 

Now if this explanation as to the course of the Gulf § 53 
Stream and its eastward tendency hold good, a current Facts 
setting from the north toward the south should’ have a this belie 
westward tendency. It should also move in a circle of 
trajection, or such as would be described by a trajectile 
moving through the air without resistance and for a great 
distance. Accordingly, and in obedience to the propelling 
powers, derived from the rate at which different parallels 
are whirled around in diurnal motion? we find the current 
from the north, which meets the Gulf Stream, on the 
Grand Banks, taking a south-westwardly direction, as 
already described.” It runs down to the tropics by the 
side of the Gulf Stream, and stretches as far to the west 
as our own shores will allow. Yet, in the face of these Opinion ot 


facts, and in spite of this force, both Major Rennel and nel tnd 
M. Arago make the coasts of the United States and the 

Shoals of Nantucket to turn the Gulf Stream toward the 

east. 

But there are other forces operating upon the Gulf $ 54 
Stream. They are derived from the effect of changes in eeeucs 
the waters of the whole ocean, as produced by changes forces 
in their temperature from time to time. As the Gulf 
Stream leaves the coasts of the United States, it begins 
to vary its position according to the seasons; the limit 
of its northern edge, as it passes the meridian of Cape 
Race (Plate VI.), being in winter about latitude 40-412, 
and in September, when the sea is hottest, about latitude 


45-46°. The trough of the Gulf Stream, therefore, may 


1 § 46, 2 $3 21. SESEG: * Plate IX. 5 § 45. 


CHAPTER 
L 


— 


§ 55 


Changes 
in the tem- 
perature 
of the 
ocean. 


30 THE PHYSICAL GEOGRAPHY OF THE SEA. 


be supposed to waver about in the ocean not unlike a 
pennon in the breeze. Its head is confined between the 
shoals of the Bahamahs and the Carolinas; but that part 
of it which stretches over toward the Grand Banks of 
Newfoundland is, as the temperature of the waters of the 
ocean changes, first pressed down toward the south, and 
then again up toward the north, according to the season 
of the year. 

To appreciate the extent of the force by which it 
is so pressed, let us imagine the waters of the Gulf 
Stream to extend all the way to the bottom of the sea, 
so as completely to separate, by an impenetrable liquid 
wall, if you please, the waters of the ocean on the right 
from the waters in the ocean on the left of the stream. 
It is the height of summer: the waters of the sea on 
either hand are for the most part in a liquid state, and 
the Gulf Stream, let it be supposed, has assumed a nor- 
mal condition between the two divisions, adjusting itself 
to the pressure on either side, so as to balance them 
exactly and be in equilibrium. Now, again, it is the 
dead of winter, and the temperature of the waters over 
an area of millions of square miles in the North Atlantic 
has been changed many degrees, and this change of tem- 
perature has been followed by a change in the specific 
gravity of those waters, amounting, no doubt, in the 
aggregate, to many hundred millions of tons, over the 
whole ocean ; for sea water, unlike fresh,’ contracts 
to freezing. Now, is it probable that, in passing from 
their summer to their winter temperature, the sea waters 
to the right of the Gulf Stream should change their spe- 
cific gravity exactly as much in the aggregate as do the 


1 § 31, 


THE GULF STREAM. ot 


waters in the whole ocean to the left of it? If not, the 
difference must be compensated by some means. Sparks 
are not more prone to fly upward, nor water to seek its 
level, than Nature is sure with her efforts to restore equi- 
librium in both sea and air whenever, wherever, and by 
whatever it be disturbed. Therefore, though the waters of 
the Gulf Stream do not extend to the bottom, and though 
they be not impenetrable to the waters on either hand, 
yet, seeing that they have a waste of waters on the right, 
and a waste of waters on the left, to which’ they offer a 
sort of resisting permeability, we are enabled to compre- 
hend how the waters on either hand, as their specific 
gravity is increased or diminished, will impart to the 
trough of this stream a vibratory motion, pressing it now 
to the right, now to the left, according to the seasons and 
the consequent changes of temperature in the sea. 

Plate VI. shows the limits of the Gulf Stream for 
March and September. The reason for this change of 
position is obvious. The banks of the Gulf Stream are 
cold water. In winter, the volume of cold water on 
the American, or left side of the stream, is greatly in- 
creased. It must have room, and gains it by pressing 
the warmer waters of the stream farther to the south, or 
right. In September, the temperature of these cold 
waters is modified; there is not such an extent of them, 
and then the warmer waters, in turn, press them back, 
and so the pendulum-like motion is preserved. 

The observations made by the United States Coast 
Survey indicate that there are in the Gulf Stream 
threads of warmer, separated by streaks of cooler water. 
See Plate VI., in which these are shown; they are marked 


wm 
i) 


CHAPTER 
I. 


Vibratory 
motion. 


§ 56 


Its limits 
in March 
and Sep- 
tember. 


SB 
Streaks of 


warm and 
cold water 


CHAPTER 
I. 


Supposed 
CaUss. 


oo THE PHYSICAL GEOGRAPHY OF THE SEA. 


x, y,%. Figure A may be taken to represent a thermo- 
metrical cross section of the stream opposite the Capes of 
Virginia, for instance; the top of the curve representing 
the thermometer in the threads of the warmer water, and 
the depressions the height of the same instrument in the 
streaks of cooler water between; thus exhibiting, as one 
sails from America across the Gulf Stream, a remarkable 
series of thermometrical elevations and depressions in the 
surface temperature of this mighty river in the sea. 
These streaks, z, y, z, are not found in the Gulf Stream 
as it issues from its fountain, and I have thought them 
to be an incident of the process by which the waters 
of the Stream gradually grow cool. Suppose a perfect 
calm over this stream, and that all the water on the 
top of it to the depth of ten feet were suddenly, as 
it runs along in a winter's day, to be stricken by the 
wand of some magician, and reduced from the tempera- 
ture of 75° to that of 32°, the water below the depth of 
ten feet remaining at 75° as before. How would this 
cold and heavy water sink? Like a great water-tight 
floor or field of ice as broad as the Gulf Stream, and 
loaded to sinking? And how would the warm water 
rise to the top? By running out under this floor or 
field, rising up over the edges, and flowing back to the 
middle? I think not; on the contrary, I suppose the 
warm water would rise up here and there in streaks, and 
that the cold would go down in streaks or seams. The 
process would be not unlike what we see going on in a 
fountain which is fed by one or more bubbling springs 
from below. We can see the warm water rising up in a 
column from the orifice below, and in winter the water 


THE GULF STREAM. 33 


on the top first grows cool and then sinks, Now, ima- 
gine the fountain to be a long and narrow stream, and 
this orifice to be a fissure running along at the bottom in 
the middle of it, and feeding it with warm water. We 
can well imagine that there would be a seam of water 
rising up all the way in the middle of the stream, and 
that a delicate thermometer would, in cold weather, show 
a marked difference of temperature between the water as 
it rises up in this seam, and that going down on either 
side after it has been cooled. Now, if we make our ima- 
ginary stream broader, and place at a little distance an- 
other fissure parallel with the first, and also supplying 
warm water, there would be between the two a streak of 
cooler water descending after having parted with a cer- 
tain degree of heat at the surface, and thus we would 
have repeated the ribbons of cold and warm water which 
the Coast Survey has found in the Gulf Stream. 

The hottest water in the Gulf Stream is also the 
lightest ; as it rises to the top, it is cooled both by eva- 
poration and exposure, when the surface is replenished 
by fresh supplies of hot water from below. Thus, in a 
winter's day, the waters at the surface of the Gulf 
Stream off Cape Hatteras may be at 80°, and at the 
depth of five hundred fathoms—three thousand feet—as 
actual observations show, the thermometer will stand at 
57°. Following the stream thence off the Capes of Vir- 
ginia, one hundred and twenty miles, it will be found— 
the water-thermometer having been carefully noted all 
the way—that it now stands a degree or two less at the 
surface, while all below is cooler. In other words, the 
stratum of water at 57°, Wee was three thousand feet 


CHAPTER 
I, 


Tempera- 
ture of Gulf 
Streain. 


34 THE PHYSICAL GEOGRAPHY OF THE SEA. 


ezarter below the surface off Hatteras, has, in a course of one 


—— 


§ 60 


Its effect 
on the 
climate of 
Western 
Europe. 


hundred and twenty or one hundred and thirty miles in 
a horizontal direction, ascended, vertically, six hundred 
feet ; that is, this stratum has run up hill with an ascent 
of five or six feet to the mile. 

As a rule, the hottest water of the Gulf Stream is at 
or near the surface; and as the deep-sea thermometer 
is sent down, it shows that these waters, though still far 
warmer than the water on either side at corresponding 
depths, gradually become less and less warm until the 
bottom of the current is reached. There is reason to be- 
lieve that the warm waters of the Gulf Stream are no- 
where permitted, in the oceanic economy, to touch the 
bottom of the sea. There is everywhere a cushion of 
cool water between them and the solid parts of the 
earth’s crust. This arrangement is suggestive, and strik- 
ingly beautiful. One of the benign offices of the Gulf 
Stream is to convey heat from the Gulf of Mexico, where 
otherwise it would become excessive, and to dispense it 
in regions beyond the Atlantic, for the amelioration of 
the climates of the British Islands and of all Western 
Europe. Now, cold water is one of the best non-conduc- 
tors of heat, and if the warm water of the Gulf Stream 
was sent across the Atlantic in contact with the solid 
crust of the earth—comparatively a good conductor of 
heat—instead of being sent across, as it is, in contact 
with a cool, non-conducting cushion of cool water to fend 
it from the bottom, all its heat would be lost in the first 
part of the way, and the soft climates of both France 
and England would be as that of Labrador, severe in the 
extreme, and ice-bound. | 


INFLUENCE OF THE GULF STREAM UPON CLIMATES. $35 


CHAPTER II. 


INFLUENCE OF THE GULF STREAM UPON CLIMATES, 


How the Climate of England is regulated by it, § 61.—Isothermal Lines of the 
Atlantic, 65.—Deep-sea Temperatures under the Gulf Stream, 68.—Currents 
indicated by the Fish, 70.—Sea-nettles, 73.—Climates of the Sea, 75.—Offices 
of the Sea, 76.—Influence of the Gulf Stream upon the Meteorology of the 
Ocean, 78.—Furious Storms, 80.—Dampness of the English Climate due to the 
Gulf Stream, 83.—Its Influence upon Storms, 85.—Wreck of the Steamer San 
Francisco, 88.—Influence of the Gulf Stream upon Commerce and Navigation, 
96.—Used for finding Longitude, 103.—Commerce in 1769, 106. 


MopDERN ingenuity has suggested a beautiful mode of 
warming houses in winter. It is done by means of hot 
water. The furnace and the ecaldron are sometimes 
placed at a distance from the apartments to be warmed. 
It is so at the Observatory. In this case, pipes are used 
to conduct the heated water from the caldron under the 
superintendent’s dwelling over into one of the basement 
rooms of the Observatory, a distance of one hundred feet. 
These pipes are then flared out so as to present a large 
cooling surface; after which they are united into one 
again, through which the water, being now cooled, returns 
of its own accord to the caldron. Thus cool water is re- 
turning all the time and flowing in at the bottom of the 
caldron, while hot water is continually flowing out at the 
top. 

The ventilation of the Observatory is so arranged that 
the circulation of the atmosphere through it is led from 
this basement room, where the pipes are, to all other 
parts of the building ; and in the process of this circulation, 


CHAPTER 
Il. 


§ 61 
Principle 


of heating 
apparatus, 


CHAPTER 


§ 62 


Similarity 
to the Gulf 
Stream. 


§ 63 


Effect on 
European 
climate, 


36 THE PHYSICAL GEOGRAPHY OF THE SEA. 


the warmth conveyed by the water to the basement is 
taken thence by the air and distributed over all the 
rooms. Now, to compare small things with great, we 
have, in the warm waters which are confined in the Gulf 
of Mexico, just such a heating apparatus for Great Britain, 
the North Atlantic, and Western Europe. 

The furnace is the torrid zone; the Mexican Gulf and 
Caribbean Sea are the caldrons; the Gulf Stream is 
the conducting pipe. From the Grand Banks of New- 
foundland to the shores of Europe is the basement—the 
hot-air chamber—in which this pipe is flared out so as 
to present a large cooling surface. Here the circulation 
of the atmosphere is arranged by nature ; and it is such, 
that the warmth thus conveyed into this warm-air cham- 
ber of mid-ocean is taken up by the genial west winds, 
and dispensed, in the most benign manner, throughout 
Great Britain and the west of Europe. 

The maximum temperature of the water-heated air- 
chamber of the Observatory is about 90°. The maxi- 
mum temperature of the Gulf Stream is 86°, or about 9° 
above the ocean temperature due the latitude. Increasing 
its latitude 10°, it loses but 2° of temperature ; and, after 
having run three thousand miles toward the north, it still 
preserves, even in winter, the heat of summer. With 
this temperature, it crosses the 40th degree of north lati- 
tude, and there, overflowing its liquid banks, it spreads 
itself out for thousands of square leagues over the cold 
waters around, and covers the ocean with a mantle of 
warmth that serves so much to mitigate in Europe the 
rigours of winter. Moving now more slowly, but dis- 
pensing its genial influences more freely, it finally meets 


INFLUENCE OF THE GULF STREAM UPON CLIMATES. 37 


the British Islands. By these it is divided,’ one part cmaprer 
going into the polar basin of Spitzbergen, the other oat 


O : 3 Its effect 
entering the Bay of Biscay, but each with a warmth onthe 

E . climate of 

considerably above the ocean temperature. Such an im- the pritisn 
Islands. 


mense volume of heated water cannot fail to carry with 
it beyond the seas a mild and moist atmosphere. And 
this it is which so much softens climate there. 

We know not, except approximately in one or two places, § 64 

what the depth or the under temperature of the Gulf Stream 
may be; but assuming the temperature and velocity at the 
depth of two hundred fathoms to be those of the surface, Caleala- 
and taking the well-known difference between the capacity *” 
of air and of water for specific heat as the argument, 
a simple calculation will show that the quantity of heat 
discharged over the Atlantic from the waters of the Gulf 
Stream in a winter’s day, would be sufficient to raise the 
whole column of atmosphere that rests upon France and 
the British Islands from the freezing point to summer 
heat. 

Every west wind that blows crosses the stream on its Weat, 
way to Europe, and carries with it a portion of this heat affected 
to temper there the northern winds of winter. It is the we 
influence of this stream upon climate that makes Erin the 
“Emerald Isle of the Sea,’ and that clothes the shores of 
Albion in evergreen robes; while in the same latitude, on 
this side, the coasts of Labrador are fast bound in fetters 
of ice. Ina valuable paper on currents,* Mr. Redfield mr. rea- 
states that in 1831 the harbour of St. John’s, Newfound- mee on 
Jand, was closed with ice as late as the month of June; ""* 
yet who ever heard of the port of Liverpool, on the other 


* American Journal of Science, vol. xiv., p. 293. 
1 Plate IX. 


38 THE PHYSICAL GEOGRAPHY OF THE SEA. 


cuarrer Side, though 2° farther north, being closed with ice even 
— in the dead of winter? 

§65 The Thermal Chart (Plate IV.) shows this. The iso- 
ee thermal lines of 60°, 50°, &c, starting off from the 
Atlantic. parallel of 40° near the coasts of the United States, run 

off in a north-eastwardly direction, showing the same 
oceanic temperature on the European side of the Atlantic 
in latitude 55° or 60°, that we have on the western side 
in latitude 40° Scott, in one of his beautiful novels, 
tells us that the ponds in the Orkneys (latitude near 60°) 
are not frozen in winter. The people there owe their 
soft climate to this grand heating apparatus, for driftwood 
from the West Indies is occasionally cast ashore there by 
the Gulf Stream. 

§66 Nor do the beneficial influences of this stream upon 
Beneficial climate end here. ‘The West Indian Archipelago is en- 


influence : : : 
ofthe  compassed on one side by its chain of islands, and on 


onsoutn the other by the Cordilleras of the Andes, contracting 
aimate, With the Isthmus of Darien, and stretching themselves 
out over the plains of Central America and Mexico, Be- 
ginning on the summit of this range, we leave the regions 
of perpetual snow, and descend first into the tierra tem- 
plada, and then into the tierra caliente, or burning land. 
Descending still lower, we reach both the level and the 
surface of the Mexican seas, where, were it not for this 
beautiful and benign system of aqueous circulation, the 
peculiar features of the surrounding country assure us we 
should have the hottest, if not the most pestilential 
climate in the world) As the waters in these two 
caldrons become heated, they are borne off by the Gulf 
Stream, and are replaced by cooler currents through the 


INFLUENCE OF THE GULF STREAM UPON CLIMATES, 39 


Caribbean Sea ; the surface water, as it enters here, being 
3° or 4°, and that in depth 40% cooler than when it 
escapes from the Gulf. ‘Taking only this difference in 
surface temperature as an index of the heat accumulated 
there, a simple caiculation will show that the quantity 
of heat daily carried off by the Gulf Stream from those 
regions, and discharged over the Atlantic, is sufficient to 
raise mountains of iron from zero to the melting point, 
and to keep in flow from them a molten stream of metal 
greater in volume than the waters daily discharged from 
the Mississippi River. Who, therefore can calculate the 
benign influence of this wonderful current upon the 
climate of the South? In the pursuit of this subject, 
the mind is led from nature up to the great Architect of 
nature ; and what mind will the study of this subject not 
fill with profitable emotions? Unchanged and unchang- 
ing alone, of all created things, the ocean is the great 
emblem of its everlasting Creator. “He treadeth upon 
the waves of the sea,” and is seen in the wonders of the 
deep. Yea, “He calleth for its waters, and poureth them 
out upon the face of the earth.” 

In obedience to this call, the aqueous portion of our 
planet preserves its beautiful system of circulation, By 
it heat and warmth are dispensed to the extra-tropical 
regions; clouds and rain are sent to refresh the dry 
land ; and by it cooling streams are brought from Polar 
Seas to temper the heat of the torrid zone. At the 
depth of two hundred and forty fathoms, the temperature 


* Temperature of the Caribbean Sea (from the journals of Mr. Dunsterville): 
Surface temperature: 83°, September; 84°, July; 83°-863°, Mosquito Coast. 
Temperature in depth: 48°, 240 fathoms; 43°, 886 fathoms; 42°, 450 fathoms; 
43°, 500 fathoms. 


SHAPTER 
Il. 


— 


§ 67 


40 THE PHYSICAL GEOGRAPHY OF THE SKA. 


carter Of the currents setting into the Caribbean Sea has been 


found as low as 48°, while that of the surface was 85. 

Ree Another cast with three hundred and eighty-six fathoms 
etal gave 43° below against 83° at the surface. The hurri- 
s."" canes of those regions agitate the sea to great depths ; 
that of 1780 tore rocks up from the bottom seven fathoms 

deep, and cast them ashore. They therefore cannot fail 

to bring to the surface portions of the cooler water below. 

§68 At the very bottom of the Gulf Stream, when its sur- 
Atthe face temperature was 80°, the deep-sea thermometer of 


bottom 
ofGuf the Coast Survey has recorded a temperature as low as 


Stream. 
35° Fahrenheit. 

§69 These cold waters doubtless come down from the north 
we eree bo replace the warm water sent through the Gulf Stream 
Cirle to moderate the cold of Spitzbergen; for within the 

Arctic Circle the temperature at corresponding depths off 
the shores of that island is said to be only one degree 
colder than in the Caribbean Sea, while on the coasts of 
Seater Labrador, and in the Polar Seas, the temperature of the 
Seas. water beneath the ice was invariably found by Lieutenant 
De Haven at 28°, or 4° below the melting point of fresh- 
ce att water ice. Captain Scoresby relates, that on the coast 
land. of Greenland, in latitude 72°, the temperature of the air 
was 42°; of the water, 84°; and 29° at the depth of 
one hundred and eighteen fathoms. He there found a 
surface current setting to the south, and bearing with it 
this extremely cold water, with vast numbers of icebergs, 
whose centres, perhaps, were far below zero. It would 
be curious to ascertain the routes of these under currents 
on their way to the tropical regions, which they are in- 


tended to cool. One has been found at the equator’ two 


1 g 23, 


INFLUENCE OF THE GULF STREAM UPON CLIMATES, 41 


hundred miles broad, and 23° colder than the surface cuarrea 
water. Unless the land or shoals intervene, it no doubt anc 
comes down in a spiral curve, approaching in its course 

the great circle route. 

Perhaps the best indication as to these cold currents § 70 
may be derived from the fish of the sea. The whales currents 
first pointed out the existence of the Gulf Stream by by fish 
avoiding its warm waters. Along our own coasts, all 
those delicate animals and marine productions which de- 
light in warmer waters are wanting; thus indicating, by 
their absence, the cold current from the north now known 
to exist there. In the genial warmth of the sea about 
the Bermudas on one hand, and Africa on the other, we 
tind in great abundance those delicate shell-fish and coral 
formations which are altogether wanting in the same lati- 
tudes along the shores of South Carolina. The same 
obtains in the west coast of South America; for there the 
cold current almost reaches the line before the first sprig 
of coral is found to grow. 

A few years ago, great numbers of bonita and alber- § 71 
core—tropical fish—following the Gulf Stream, entered 
the English Channel, and alarmed the fishermen of Corn- 
wall and Devonshire by the havoc which they created 
among the pilchards there. 

It may well be questioned if our Atlantic cities and g 79 
towns do not owe their excellent fish-markets, as well as 
our watering-places their refreshing sea-bathing in sum- 
mer, to this stream of cold water. The temperature of 
the Mediterranean is 4° or 5° above the ocean tempera- 
ture of the same latitude, and the fish there are, for the 
most part, very indifferent. On the other hand, the tem- 


42 THE PHYSICAL GEOGRAPHY OF THE SEA. 


cuapter perature along our coast is several degrees below that of 
Il. 


Effects of 
tempera- 
ture on 
fish. 


the ocean, and from Maine to Florida our tables are sup- 
plied with the most excellent of fish, The sheep’s-head, 
so much esteemed in Virginia and the Carolinas, when 
taken on the warm coral banks of the Bahamas, loses its 
flavour, and is held in no esteem. The same is the case 
with other fish: when taken in the cold water of that 
coast, they have a delicious flavour, and are highly 
esteemed ; but when taken in the warm water on the 
other edge of the Gulf Stream, though but a few miles 
distant, their flesh is soft, and unfit for the table. The 
temperature of the water at the Balize reaches 90°. The 
fish taken there are not to be compared with those of the 
same latitude in this cold stream. New Orleans, there- 
fore, resorts to the cool waters on the Florida coasts for 
her choicest fish. The same is the case in the Pacific. 
A current of cold water’ from the south sweeps the 
shores of Chili, Peru, and Columbia, and reaches the Galli- 
pagos Islands under the line. Throughout this whole 
distance, the world does not afford a more abundant or 
excellent supply of fish, Yet out in the Pacific, at the 
Society Islands, where coral abounds, and the water pre- 
serves a higher temperature, the fish, though they vie in 
gorgeousness of colouring with the birds, and plants, and 
insects of the tropics, are held in no esteem as an article 
of food. I have known sailors, even after long voyages, 
still to prefer their salt beef and pork to a mess of fish 
taken there. The few facts which we have bearing upon 
this subject seem to suggest it as a point of the inquiry 
to be made, whether the habitat of certain fish does not 
indicate the temperature of the water, and whether these 


2 § 455. 


INFLUENCE OF THE GULF STREAM UPON CLIMATES, 43 


cold and warm currents of the ocean do not constitute the cnaprsa 
great highways through which migratory fishes travel ee 
from one region to another. Why should not fish be as 
much the creatures of climate as plants, or as birds, and 
other animals of land, sea, and air? Indeed, we know 

that some kinds of fish are found only in certain climates. 

In other words, they live where the temperature of the 
water ranges between certain degrees. 

Navigators have often met with vast numbers of ¢§ 73 
young sea-nettles (medusw) drifting along with the Gulf sea-netties 
Stream. They are known to constitute the principal 
food for the whale; but whither bound by this route has 
caused much speculation, for it is well known that the 
habits of the right whale are averse to the warm waters 
of this stream. An intelligent sea-captain informs me 
that, several years ago, in the Gulf Stream on the coast 
of Florida, he fell in with such a “school of young sea- 
nettles as had never before been heard of.” The sea was 
covered with them for many leagues. He likened them, 
in appearance on the water, to acorns floating on a 
stream; but they were so thick as to completely cover 
the sea. He was bound to England, and was five or six Anecdote 
days in sailing through them. In about sixty days after- 
ward, on his return, he fell in with the same school off 
the Western Islands, and here he was three or four days 
in passing them again. He recognized them as the same, 
for he had never before seen any like them; and on both 
occasions he frequently hauled up bucketfuls and ex- 
amined them. 

Now, the Western Islands is the great place of resort § 74 
for whales: and at first there is something curious to vs 


44 THE PHYSICAL GEOGRAPHY OF THE SEA. 


cuapter in the idea that the Gulf of Mexico is the harvest-field, 


Il. 


— 


§ 75 


and the Gulf Stream the gleaner which collects the fruit- 
age planted there, and conveys it thousands of miles off 
to the hungry whale at sea. But how perfectly in unison 
is it with the kind and providential care of that great 
and good Being which feeds the young ravens when they 
ery, and caters for the sparrow ! 

The sea has its climates as well as the land. They 


Climatesot hoth change with the latitude; but one varies with the 


the sea. 


Offices of 
the sea 


elevation above, the other with the depression below the 
sea level. The climates in each are regulated by circula- 
ition; but the regulators are, on the one hand, winds; on 
the other, currents. 

The inhabitants of the ocean are as much the creatures 
of climate as are those of the dry land; for the same 
Almighty hand which decked the lily and cares for the 
sparrow, fashioned also the pearl and feeds the great 
whale, and adapted each to the physical conditions by 
which his providence has surrounded it. Whether of the 
land or the sea, the inhabitants are all his creatures, 
subjects of his laws, and agents in his economy. ‘The 
sea, therefore, we may safely infer, has its offices and 
duties to perform; so, may we infer, have its currents, 
and so, too, its inhabitants ; consequently, he who under- 
takes to study its phenomena must cease to regard it as 
a waste of waters. He must look upon it as a part of 
that exquisite machinery by which the harmonies of 
nature are preserved, and then he will begin to perceive 
the developments of order and the evidences of design ; 
these make it a most beautiful and interesting subject for 
contemplation. 


INFLUENCE OF THE GULF STREAM UPON CLIMATES. 45 


To one who has never studied the mechanism of a 
watch, its main-spring or the balance-wheel is a mere 
piece of metal. He may have looked at the face of the 
watch, and, while he admires the motion of its hands, and 
the time it keeps, or the tune it plays, he may have 
wondered in idle amazement as to the character of the 
machinery which is concealed within. Take it to pieces, 
and show him each part separately, he will recognize 
neither design, nor adaptation, nor relation between them; 
but put them together, set them to work, point out the 
offices of each spring, wheel, and cog, explain their move- 
ments, and then show him the result; now he perceives 
that it is all one design; that, notwithstanding the num- 
ber of parts, their diverse forms and various offices, and 
the agents concerned, the whole piece is of one thought, 
the expression of one idea. He now rightly concludes that 
when the main-spring was fashioned and tempered, its 
relation to all the other parts must have been considered ; 
that the cogs on this wheel are cut and regulated— 
adapted—to the ravhets on that, &c.; and his final con- 
clusion will be, that such a piece of mechanism could not 
have been produced by chance; for the adaptation of the 
parts is such as to show it to be according to design, and 
obedient to the will of one intelligence. So, too, when 
one looks out upon the face of this beautiful world, he 
may admire its lovely scenery, but his admiration can 
never grow into adoration unless he will take the trouble 
to look behind and study, in some of its details at least, 
the exquisite system of machinery by which such beauti- 
ful results are brought about. To him who does this, 
the sea, with its physical geography, becomes as the main- 


CHAPTER 
Ii. 


$7 


Reflec- 
tions, 


CHAPTER 


§ 78 


Influence 
of the Gulf 
Stream on 
the meteo- 
rology of 
the sea. 


46 THE PHYSICAL GEOGRAPHY OF THE SEA. 


spring of a watch; its waters, and its currents, and its 
salts, and its inhabitants, with their adaptations, as balance- 
wheels, cogs and pinions, and jewels. Thus he perceives 
that they, too, are according to design; that they are the 
expression of One Thought, a unity with harmonies which 
One Intelligence, and One Intelligence alone, could utter. 
And when he has arrived at this point, then he feels that 
the study of the sea, in its physical aspect, is truly su- 
blime. It elevates the mind and ennobles the man. The 
Gulf Stream is now no longer, therefore, to be regarded 
by such an one merely as an immense current of warm 
water running across the ocean, but as a balance~-wheel— 
a part of that grand machinery by which air and water 
are adapted to each other, and by which this earth itself 
is adapted to the well-being of its inhabitants—of the 
flora which decks, and the fauna which enlivens its 
surface. 

Let us now consider the influence of the Gulf Stream 
upon the meteorology of the ocean. 

To use a sailor expression, the Gulf Stream is the great 
“weather breeder” of the North Atlantic Ocean. The 
most furious gales of wind sweep along with it; and the 
fogs of Newfoundland, which so much endanger navi- 
gation in winter, doubtless owe their existence to the 
presence, in that cold sea, of immense volumes of warm 
water brought by the Gulf Stream. Sir Philip Brooke 
found the air on each side of it at the freezing point, 
while that of its waters was 80° “The heavy, warm, 
damp air over the current produced great irregularities 
in his chronometers.” The excess of heat daily brought 
into such a region by the waters of the Gulf Stream 


INFLUENCE OF THE GULF STREAM UPON CLIMATES. 47 


wouid, if suddenly stricken from them, be sufficient to onarrza 
make the column of superincumbent atmosphere hotter —— 
than melted iron. 

With such an element of atmospherical disturbance in g 79 
its bosom, we might expect storms of the most violent Itsiiavility 
kind to accompany it in its course. Accordingly, the ae 
most terrific that rage on the ocean have been known to 
spend their fury within or near its borders. 

Our nautical works tell us of a storm which forced this g gg 

stream back to its sources, and piled up the water in the 
Gulf to the height of thirty feet. The Ledbury Snow 
attempted to ride it out. When it abated, she found her- 
self high up on the dry land, and discovered that she had 
let go her anchor among the tree-tops on Elliott’s Key. 
The Florida Keys were inundated many feet; and, it is 
said, the scene presented in the Gulf Stream was never 
surpassed in awful sublimity on the ocean. The water 
thus dammed up is said to have rushed out with wonder- 
ful velocity against the fury of the gale, producing a sea 
that beggared description. 

The “great hurricaue” of 1780 commenced at Bar- g g1 
badoes. In it the bark was blown from the trees, and Great pur 
the fruits of the earth destroyed; the very bottom and ae 
depths of the sea were uprooted, and the waves rose to 
such a height that forts and castles were washed away, 
and their great guns carried about in the air like chaff; 
houses were razed, ships were wrecked, and the bodies of 
men and beasts lifted up in the air and dashed to pieces 
in the storm. At the different islands, not less than 
twenty thousand persons lost their lives on shore; while 
farther to the north, the “ Stirling Castle” and the “ Dover 


CHAPTER 


— 


§ 82 


British 
Admiralty 
investiga- 
tion. 


§ 83 


Dampness 
of English 
climate 
due to the 
Gulf 
Stream. 


§ 84 


2 85 


48 THE PHYSICAL GEOGRAPHY OF THE SEA. 


Castle” men-of-war went down at sea, and fifty sail were 
driven on shore at the Bermudas. 

Several years ago, the British Admiralty set on foot 
inquiries as to the cause of the storms in certain parts 
of the Atlantic, which so often rage with diastrous effects 
to navigation. The result may be summed up in the 
conclusion to which the investigation led: that they are 
occasioned by the irregularity between the temperature 
of the Gulf Stream and of the neighbouring regions, both 
in the air and water. 

The habitual dampness of the climate of the British 
Islands, as well as the occasional dampness of that along 
the Atlantic coasts of the United States when easterly 
winds prevail, is attributable also to the Gulf Stream. 
These winds come to us loaded with vapours gathered from 
its warm and smoking waters. The Gulf Stream carries 
the temperature of summer, even in the dead of winter, 
as far north as the Grand Banks of Newfoundland. 

One of the poles of maximum cold is, according to 
theory, situated in latitude 80° north, longitude 100° west. 
It is distant but little more than two thousand miles, in 
a north-westwardly direction, from the summer-heated 
waters of this stream. This proximity of extremes of 
greatest cold and summer heat will, as observations are 
multiplied and discussed, be probably found to have much 
to do with the storms that rage with such fury on the 
left side of the Gulf Stream. 

I am not prepared to maintain that the Gulf Stream 
is really the “ Storm King” of the Atlantic, which has 
power to control the march of every gale that is raised 
there; but the course of many gales has been traced 
from the place of their origin directly to the Gulf 
Stream. Gales that take their rise on the coast of Africa, 


INFLUENCE OF THE GULF STREAM UPON CLIMATES. 49 


and even as far down on that side as the parallel of cartes 
10° or 15° north latitude, have, it has been shown by = 


an examination of log-books, made straight for the Gulf aitacat 
Stream; joining it, they have then been known to turn Sa 
about, and, travelling with this stream, to recross the 
Atlantic, and so reach the shores of Europe. In this way 

the tracks of storms have been traced out and followed 

for a week or ten days. Their path is marked by wreck 

and disaster. 

Plate X. was prepared by Lieutenant B. 8. Porter, from § 86 
data furnished by the log-books at the Observatory. It 
represents one of these storms that commenced in August 
1848. It commenced more than a thousand miles from 
the Gulf Stream, made a straight course for it, and tra- 
velled with it for many days. 

The dark shading shows the space covered by the gale, 
and the white line in the middle shows the axis of the 
gale, or the line of minimum barometric pressure. There 
are many other instances of similar gales. Professor Espy 
informs us that he also has traced many a gale from the 
land out toward the Gulf Stream. 

Now, what should attract these terrific storms to the § 87 
Gulf Stream? Sailors dread storms in the Gulf Stream 
more than they do in any other part of the ocean. It is 
not the fury of the storm alone that they dread, but it is 
the “ugly sea” which these storms raise. The current of 
the stream running in one direction, and the wind blow- 
ing in another, creates a sea that is often frightful. 

In the month of December 1853, the fine new steam § 88 
ship San Francisco sailed from New York with a regi seis 
ment of United States troops on board, bound around Francisco. 
Cape Horn for California. She was overtaken, while 
crossing the Gulf Stream, by a gale of wind, in which 


a 


CHAPTER 
TI, 


— 


Apprehen- 
sions for 
those on 
board. 


§ 89 


§ 90 


Search 
made for 


50 THE PHYSICAL GEOGRAPHY OF THE SEA. 


she was dreadfully crippled. Her decks were swept, and 
by one single blow of those terrible seas that the storms 
there raise, one hundred and seyventy-nine souls, officers 
and soldiers, were washed overboard and drowned. 

The day after this disaster she was seen by one vessel, 
and again the next day, December 26th, by another, but 
neither of them could render her any assistance. 

When these two vessels arrived in the United States, 
and reported what they had seen, the most painful appre- 
hensions were entertained by friends for the safety of 
those on board the steamer. Vessels were sent out to 
search for and relieve her. But which way should these 
vessels go? Where should they look ? 

An appeal was made to know what light the systera 
of researches carried on at the National Observatory con- 
cerning winds and currents could throw upon the sub- 
ject. 

The materials that had been discussed were examined, 
and a chart was prepared to show the course of the Gulf 
Stream at that season of the year. (See the limits of 
the Gulf Stream for March, Plate VI.) Upon the sup- 
position that the steamer had been completely disabled, 
the lines a b were drawn to define the limits of her 
drift. Between these two lines, it was said, the steamer, 
if she could neither steam nor sail after the gale, had 
drifted. 

By request, I prepared instructions for two revenue 
cutters that were sent to search for her. One of them 
being at New London, was told to go along the dotted 
track leading to ¢, expecting thereby to keep inside of the 
line along which the steamer had drifted. with the view 
of intercepting and speaking homeward-bound vessels 
that might have seen the wreck. 


INFLUENCE OF THE’GULF STREAM UPON CLIMATES. 51 


The cutter was to proceed to c, where she might cnapres 
expect to fall in with the line of drift taken by the pe 
steamer. The last that was seen of that ill-fated vessel ° ie 
was when she was at 0, but a few miles from ¢. So, if 
the cutter had been in time, she had instructions that 
would have taken her in sight of the object of her 
search. 

It is true that, before the cutter sailed, the Kilby, § 92 
the Three Bells, and the Antarctic, unknown to anxious 
friends at home, had fallen in with and relieved the 
wreck; but that does not detract from the system of 
observations, of the results of which, and their practical 
application, it is the object of this work to treat. 

A beautiful illustration of their usefulness is the fact § 93 
that, though the bark Kilby lost sight of the wreck at 
night, and the next morning did not know which way 
to look for it, and could not find it, yet, by a system 
of philosophical deduction, we on shore could point out 
the whereabouts of the disabled steamer so closely, that 
vessels could be directed to look for her exactly where 
she was to be seen. 

These storms, for which the Gulf Stream has such § 94 

attraction, and over which it seems to exercise so much jel 
control, are said to be, for the most part, whirlwinds. 
All boys are familiar with miniature whirlwinds on 
shore. They are seen, especially in the autumn, sweep- 
ing along the roads and streets, raising columns of dust, 
leaves, &c., which rise up like inverted cones in the air, 
and gyrate about the centre or axis of the storm. Thus, 
while the axis, and the dust, and the leaves, and all 
those things which mark the course of the whirlwind, are 
travelling in one direction, it may be seen that the wind 
is blowing around this axis in all directions. 


52 THE PHYSICAL GEOGRAPHY OF THE SEA. 


CHAPTER Just so with some of these Gulf Stream storms. That 
represented on Plate X. is such a one. It was a rotary 


Cyclones storm. Mr. Piddington, an eminent meteorologist of Cal- 
cutta, calls them Cyclones. 

§95 Now, what should make these storms travel toward 
the Gulf Stream, and then, joining it, travel along 
with its current? It is the high temperature of its 
waters, say mariners. But why, or wherefore, should 
the spirits of the storm obey in this manner the influence 
of these high temperatures, philosophers have not been 
able to explain. 

§96 The influence of the Gulf Stream upon commerce and 
navigation. 

ynuenes Formerly the Gulf Stream controlled commerce across 
Streamon the Atlantic by governing vessels in their routes through 
and navi this ocean to a greater extent than it does now, and 
aes simply for the reason that ships are faster, nautical instru- 
ments better, and navigators are more skilful now than 
formerly they were. 

§97 Up to the close of the last century, the navigator 
Improve. guessed as much as he calculated the place of his ship : 
navigation vessels from Europe to Boston frequently made New 

York, and thought the landfall by no means bad. Chro- 
nometors, now so accurate, were then an experiment. 
The Nautical Ephemeris itself was faulty, and gave tables 
which involved errors of thirty miles in the longitude. 
The instruments of navigation erred by degrees quite as 
much as they now do by minutes ; for the rude “ cross 
staff” and “back staff,’ the “sea-ring” and “ mariner’s 
bow,” had not yet given place to the nicer sextant and 
circle of reflection of the present day. Instances are 
numerous of vessels navigating the Atlantic in those 


INFLUENCE OF THE GULF STREAM UPUN COMMERCE. 53 


times being 6°, 8°, and even 10° of longitude out of their cuaprex 
reckoning in as many days from port. pats 

Though navigators had been in the habit of crossing § 98 
and recrossing the Gulf Stream almost daily for three on 
centuries, it never occurred to them to make use of it as means of 
a means of giving them their longitude, and of warning tangitaae 
them of their approach to the shores of this continent. 

Dr. Franklin was the first to suggest this use of it. § 99 
The contrast afforded by the temperature of its waters Dr. Frank 


and that of the sea between the Stream and the shores of Rate: 


America was striking. The dividing lne between the da 
warm and the cool waters was sharp; and this dividing 
line, especially that on the western side of the stream, 
never changed its position as much in longitude as mari- 
ners erred in their reckoning. 

When he was in London in 1770, he happened to g 109 
be consulted as to a memorial which the Board of Cus- 
toms at Boston sent to the Lords of the Treasury, stat- 
ing that the Falmouth packets were generally a fort- 
night longer to Boston than common traders were from 
London to Providence, Rhode Island. They therefore 
asked that the Falmouth packets might be sent to Provi- 
dence instead of to Boston. This appeared strange to 
the doctor, for London was much farther than Falmouth, 
and from Falmouth the routes were the same, and the 
difference should have been the other way. He, how- seenlisot 
ever, consulted Captain Folger, a Nantucket whaler, who ledge of 
chanced to be in London also; the fisherman explained aie 
to him that the difference arose from the circumstance 
that the Rhode Island captains were acquainted with the 


Gulf Stream, while those of the English packets were 


1 §2, 


54 THE PHYSICAL GEOGRAPHY OF THE SEA, 


cuarten not. The latter kept in it, and were set back sixty or 

ct seventy miles a day, while the former avoided it alto- 

gether. He had been made acquainted with it by the 

whales which were found on either side of it, but never 

Chartof in it.’ At the request of the doctor, he then traced on a 

ieeie | chart the course of this stream from the Straits of Flo- 

sue vida, The doctor had it engraved at Tower Hill, and 

sent copies of it to the Falmouth captains, who paid no 

attention to it. The course of the Gulf Stream, as laid 

down by that fisherman from his general recollection of 

it, has been retained and quoted on the charts for navi- 
gation, we may say, until the present day. 

But the investigations of which we are treating are 
beginning to throw more light upon this subject; they 
are giving us more correct knowledge in every respect 
with regard to it, and to many other new and striking 
features in the physical geography of the sea. 

§101 No part of the world affords a more difficult or dan- 
naveation gerous navigation than the approaches of our northern 
ofour coast in winter. Before the warmth of the Gulf Stream 
coasts. = was known, a voyage at this season from Europe to New 

England, New York, and even to the Capes of the Dela- 
ware or Chesapeake, was many times more trying, diffi- 
ete cult, and dangerous than it now is. In making this 
part of the coast, vessels are frequently met by snow- 
storms and gales which mock the seaman’s strength, and 
set at naught his skill. In a little while his bark becomes 
a mass of ice; with her crew frosted and helpless, she 
remains obedient only to her helm, and is kept away for 
the Gulf Stream. After a few hours’ run, she reaches its 


edge, and almost at the next bound passes from the 


1 § 70, 


INFLUENCE OF THE GULF STREAM UPON COMMERCE. 9595 


midst of winter into a sea at summer heat. Now the 
ice disappears from her apparel; the sailor bathes his 
stiffened limbs in tepid waters; feeling himself invigo- 
rated and refreshed with the genial warmth about him, 
he realizes, out there at sea, the fable of Antzeus and his 
mother Earth. He rises up and attempts to make hes 
port again, and is again, perhaps, as rudely met and beat 
back from the north-west; but each time that he is 
driven off from the contest, he comes forth from this 
stream, like the ancient son of Neptune, stronger and 
stronger, until, after many days, his freshened strength 
prevails, and he at last triumphs and enters his haven in 
safety, though in this contest he sometimes falls to rise 
no more, for it is often terrible. Many ships annually 
founder in these gales; and I might name instances, for 
they are not uncommon, in which vessels bound to Nor- 
folk or Baltimore, with their crews enervated in tropical 
climates, have encountered, as far down as the Capes of 
Virginia, snow-storms that have driven them back into 
the Gulf Stream time and again, and have kept them out 
for forty, fifty, and even for sixty days, trying to make 
an anchorage. 

Nevertheless, the presence of the warm waters of the 
Gulf Stream, with their summer heat in mid-winter, off 
the shores of New England, is a great boon to navigation. 
At this season of the year especially, the number of wrecks 
and the loss of life along the Atlantic sea-front are fright- 
ful. The month’s average of wrecks has been as high as 
three a day. How inany escape by seeking refuge from the 
cold in the warm waters of the Gulf Stream is matter of 
conjecture. Suffice it to say, that before their temperature 


CHAPTER 
Il. 


Sudden 
change. 


§ 102 


The warm 
waters of 
the Streain 
a boon to 
navigation. 


CHAPTER 
II. 


§ 103 


Import- 

ance of Dr. 
Franklin's 
discovery. 


56 THE PHYSICAL GEOGRAPHY OF THE SEA. 


was known, vessels thus distressed knew of no place of 
refuge short of the West Indies; and the newspapers of 
that day—Franklin’s Pennsylvania Gazette among them 
—inform us that it was no uncommon occurrence for ves- 
sels, bound for the Capes of the Delaware in winter, to 
be blown off and to go to the West Indies, and there 
wait for the return of spring before they would attempt 
another approach to this part of the coast. 

Accordingly, Dr. Franklin’s discovery with regard to 
the Gulf Stream temperature was looked upon as one of 
great importance, not only on account of its affording to 
the frosted mariner in winter a convenient refuge from 
the snow-storm, but because of its serving the navigator 
with an excellent land-mark or beacon for our coast in 
all weathers. And so viewing it, the doctor, through 
political considerations, concealed his discovery for a while. 
It was then not uncommon for vessels to be as much as 
10° out in their reckoning. He himself was 5°. The 
prize of £20,000, which had been offered, and partly paid 
to Harrison, the chronometer maker, for improving the 
means of finding longitude at sea, was fresh in the minds 
of navigators. And here it was thought a solution of 
the grand problem—for longitude at sea was a grand 
problem—had been stumbled upon by chance; for, on 
approaching the coast, the current of warm water in the 
Gulf Stream, and of cold water on this side of it, if tried 
with the thermometer, would enable the mariner to judge 
with great certainty, and in the worst of weather, as to 
his position, Jonathan Williams afterward, in speaking 
of the importance which the discovery of these warm and 
cold currents would prove to navigation, pertinently asked 


INFLUENCE OF THE GULF STREAM UPON COMMERCE. 57 


the question, “If these stripes of water had been distin- cuaprer 
guished by the colours of red, white, and blue, could they uae 
be more distinctly discovered than they are by the con- 
stant use of the thermometer?” And he might have 
added, could they have marked the position of the ship 
more clearly ? 

When his work on Thermometrical Navigation ap-¢ 104 
peared, Commodore Truxton wrote to him: “ Your pub- commo- 


dore Trux- 


lication will be of use to navigation, by rendering sea ton’sopin- 
voyages secure far beyond what even you yourself will coca 
immediately calculate, for I have proved the utility of 
the thermometer very often since we sailed together. 

“Tt will be found a most valuable instrument in the 
hands of mariners, and particularly as to those who are 
unacquainted with astronomical observations; ..... 
these particularly stand in need of a simple method of 
ascertaining the approach to or distance from the coast, 
especially in the winter season; for it is then that pas- 
sages are often prolonged, and ships blown off the coast 
by hard westerly winds, and vessels get into the Gulf 
Stream without its being known ; on which account they 
are often hove to by the captains’ supposing themselves 
near the coast when they are very far off (having been 
drifted by the currents). On the other hand, ships are 
often cast on the coast by sailing in the eddy of the 
Stream, which causes them to outrun their common reck- 
oning. Every year produces new proofs of these facts, 
and of the calamities incident thereto.” 

Though Dr. Franklin’s discovery was made in 1775, § 105 
yet, for political reasons, it was not generally made known 
till 1790. Its immediate effect in navigation was to 


CHAPTER 
II. 


Effect of 
Dr. Frank- 
lin’s dis- 
covery on 
navigation 


Decline 
of the 
Southern 
trade. 


§ 106 


58 THE PHYSICAL GEOGRAPHY OF THE SEA. 


make the ports of the North as accessible in winter as in 
summer. What agency this circumstance had in the 
decline of the direct trade of the South, which followed 
this discovery, would be, at least to the political econo- 
mist, a subject for much curious and interesting speculation. 
I have referred to the commercial tables of the time, and 
have compared the trade of Charleston with that of the 
northern cities for several years, both before and after 
the discovery of Dr. Franklin became generally known 
to navigators. The comparison shows an immediate 
decline in the Southern trade, and a wonderful increase 
in that of the North. But whether this discovery in 
navigation, and this revolution in trade, stand in the 
relation of cause and effect, or be merely a coincidence, 
let others judge. 

In 1769, the commerce of the two Carolinas equalled 
that of all the New England States together; it was 
more than double that of New York, and exceeded that 
of Pennsylvania by one-third.* In 1792, the exports 
from New York amounted in value to two millions and 


* From M‘Pherson’s Annals of Commerce.—Exports and Imports in 1769, 
valued in Sterling Money. 


EXPORTS. 
| To Gr. Britain. | So. of Europe. West Indies. Africa. Total. 

ese PACAP ees ee CA ck GA) EE at 
New England...../142,775 12 9} 81,173 16 2/308,427 9 6] 17,713 0 9 {550,089 19 2 
ING WaniOlKrccsesess 113,282 8 8| 50,885 13 0] 66,324 17 5] 1,818 2 6/281,906 17 
Pennsylvania.... 28,112 6 9/208,762 11 11|178,331 7 8 560 9 9 /410,756 16 1 

North and South 
Carolina.........(405,014 18 1/ 76,119 12 10] 87,758 19 3 691 12 1 569,584 17 3 


IMPORTS. 
New England...../228,695 11 25,408 17 9 |314,749 14 5 180 0 0[|564,084 38 
New York......... 75,930 19 14,927 7 0/)|897,420 4 697 10 0|188,976 1 
Pennsylvania..-..|204,979 17 4) 14,249 8 4/180,591 12 4 399,830 18 0 
North and South 


Carolina....+0.1827,084 8 6] 7,099 5 10! 76,269 17 11/137,620 10 0]|535,714 2 3] 


a D> 
—) 
wo oo 


INFLUENCE OF THE GULF STREAM UPON COMMERCE. 59 


a half; from Pennsylvania to 3,820,000 dollars; and cuarren 

from Charleston alone to 3,834,000 dollars. ass 
But in 1795—by which time the Gulf Stream began § 107 

to be as well understood by navigators as it now is, and Increase 


of the 
the average passages from Europe to the North were Northen 


shortened nearly one-half, while those to the South re- es 
mained about the same—the customs at Philadelphia 
alone amounted to 2,941,000 dollars,* or more than one- 
half of those collected in all the states together. 

Nor did the effect of the doctor’s discovery end here. g 198 
Before it was made, the Gulf Stream was altogether insi- Further 
dious in its effects. By it vessels were often drifted many Baca 
miles out of their course without knowing it; and in bad “” 
and cloudy weather, when many days would intervene 
from one observation to another, the set of the current, 
though really felt for but a few hours during the interval, 
could only be proportioned out equally among the whole 
number of days, Therefore navigators could have only 
very vague ideas either as to the strength or the actual 


limits of the Gulf Stream, until they were marked out to 


* Value of Exports in Dollars.} 


1791. 1792. 1793. 1794. 1795. 1796. 
Massachusetts...........000. 2,519,651] 2,888,104) 3,755,847) 5,292,441) 7,117,907) 9,949,345 
New York see} 2,505,465} 2,535,790) 2,932,370) 5,442,000]10,504,000) 12,208,027 
Pennsylvania ...c0..c.sc00- 3,436,000} 3,820,000) 6,958,000} 6,643,000]11,518,000!17,513,866 


South Carolina.............. 2,695,000} 2,428,000} 3,191,000! 3,868,000} 5,998,000) 7,620,000 


Duties on Imports in Dollars. 


1793. 1794. 1795. 


Massachusetts ..|1,006,000 723,000} 1,044,000} 1,121,000] 1,520,000) 1,460,000) 3,055,000 
New: York....... 1,834,000) 1,173,000) 1,204,000) 1,878,000} 2,028,000] 2,187,000)10,712,000 
Pennsylvania,...!1,466,000) 1,100,000} 1,823,000] 1,498,000] 2,300,000] 2,050,000) 2,207,000 
South Carolina..| 523,000 359,000] 360,000] 661,000 722,000 66,000] 389,000 


2 Doc. No. 330, H. R., 2d Session, 25th Congress. Some of its statements do not agree 
with those taken from M‘Pherson, and previously quoted. 


60 THE PHYSICAL GEOGRAPHY OF THE SEA. 


onartzr the Nantucket fishermen by the whales, or made known 

ae by Captain Folger to Dr. Franklin. The discovery, there- 

fore, of its high temperature assured the navigator of the 

presence of a current of surprising velocity, and which, 

now turned to certain account, would hasten, as it had 
retarded his voyage in a wonderful degree. 

§109 Such, at the present day, is the degree of perfection to 
Ealueare which nautical tables and instruments have been brought, 
nautical that the navigator may now detect, and with great cer- 
a tainty, every current that thwarts his way. He makes 
cate great use of them. Colonel Sabine, in his passage, a few 
years ago, from Sierra Leone to New York, was drifted 
one thousand six hundred miles of his way by the force 
of currents alone; and, since the application of the ther- 
mometer to the Gulf Stream, the average passage from 
England has been reduced from upwards of eight weeks 
to a little more than four. 

§ 110 Some political economists of America have ascribed the 
Decline of oyeat decline of Southern commerce which followed the 


Southern 


pomnietee adoption of the Constitution of the United States to the 
ascribed to 
legislation. protection given by legislation to Northern interests. But 


sea I think these statements and figures show that this decline 

was in no small degree owing to the Gulf Stream and the 

water thermometer; for they changed the relations of 

Charleston—the great Southern emporium of the times— 

removing it from its position as a half-way house, and 
placing it in the category of an outside station. 

§111 The plan of our work takes us necessarily into the air, 

Necessity for the sea derives from the winds some of the most 


for aknow- 


pals striking features in its physical geography. Without a 
the winds. 


knowledge of the winds, we can neither understand the 


INFLUENCE OF THE GULF STREAM UPON COMMERCE. 61 


navigation of the ocean, nor make ourselves intelligently 
acquainted with the great highways across it. As with 
the land, so with the sea; some parts of it are as untra- 
velied and as unknown as the great Amazonian wilder- 
ness of Brazil, or the inland basins of Central Africa. To 
the south of a line extending from Cape Horn to the 
Cape of Good Hope* is an immense waste of waters. 
None of the commercial thoroughfares of the ocean lead 
through it; only the adventurous whaleman finds his way 
there now and then in pursuit of his game; but for all the 
purposes of science and navigation, it is a vast unknown 
region. Now, were the prevailing winds of the South At- 
lantic northerly or southerly, instead of easterly or westerly, 
this unploughed sea would be an oft-used thoroughfare. 

Nay, more, the sea supplies the winds with food for 
the rain which these busy messengers convey away from 
the ocean to “the springs in the valleys which run among 
the hills” To the philosopher the places which supply 
the vapours are as suggestive and as interesting for the 
instruction they afford, as the places are upon which the 
vapours are showered down. Therefore, as he who studies 
the physical geography of the land is expected to make 
himself acquainted with the regions of precipitation, so 
he who looks into the physical geography of the sea 
should search for the regions of evaporation, and for those 
springs in the ocean which supply the reservoirs among 
the mountains with water to feed the rivers; and, in order 
to conduct this search properly, he must consult the winds, 
and make himself acquainted with their “circuits.” Hence, 
in a work on the Physical Geography of the Sea, we treat 
also of the ATMOSPHERE, 


2 Plate VIII. 


ae 


—_— 


§ 112 


How this 
subject 
ought to 
be studied 


62 THE PHYSICAL GEOGRAPHY OF THE SEA. 


CHAPTER IIL. 


THE ATMOSPHERE. 


Its Connection with the Physical Geography of the Sea, § 113.—Description, 
114.—Order in Sea and Air, 119.—The Language and Eloquence of Nature, 
120.—The Trade Winds, 122.—Plate I., Circulation of the Atmosphere, 128. 
—An Illustration, 126.—Theory, 128.— Where and why the Barometer stands 
highest, 133.—The Pleiades, 142.—Trade-wind Clouds, 146.—Forces con- 
cerned, 149.—Heat and Cold, 150.—How the Winds turn about the Poles, 155, 
—Offices of the Atmosphere, 159.—Mechanical Power of, 167.—Whence come 
the Rains for the Northern Hemisphere? 169.—Quantity of Rain in each 
Hemisphere, 175.—The Saltest Portion of the Sea, 179.—The North-east Trade- 
winds take up Vapours for the Southern Hemisphere, 181.—Rainy Seasons, 
187.—In Oregon, 189.—California, 191.—Panama, 193.—Rainless Regions, 
194.—Rainy Side of Mountains, 199.—The Ghauts, 200.—The greatest Preci- 
pitation—where it takes place, 203.—Evaporation, 207.—Rate of, in India, 
210.—Adaptations of the Atmosphere, 219. 


oxapten A PHILOSOPHER of the East,” with a richness of imagery 


Ill. 


truly Oriental, describes the atmosphere as “a spherical 


§ 113 shell which surrounds our planet to a depth which is un 


The At- 
mosphere. 


known to us, by reason of its growing tenuity, as it is 
released from the pressure of its own superincumbent 
mass. Its upper surface cannot be nearer to us than 
fifty, and can scarcely be more remote than five hundred 
miles. It surrounds us on all sides, yet we see it not; it 
presses on us with a load of fifteen pounds on every 
square inch of surface of our bodies, or from seventy to 
one hundred tons on us in all, yet we do not so much as 
feel its weight. Softer than the softest down—more 
impalpable than the finest gossamer—it leaves the cob- 
web undisturbed, and scarcely stirs the lightest flower 
that feeds on the dew it supplies; yet it bears the fleets 
of nations on its wings around the world, and crushes 


* Dr, Buist, of Bombay. 


THE ATMOSPHERE. 63 


the mest refractory substances with its weight. When cuaprzs 
in motion, its force is sufficient to level the most stately aus 
forests and stable buildings with the earth—to raise the sie 


waters of the ovean into ridges like mountains, and dash ear: 
the strongest. ships to pieces like toys. It warms and 
cools by turns the earth and the living creatures that in- 
- habit it. It draws up vapours from the sea and land, 
retains them dissolved in itself, or suspended in cisterns 
of clouds, and throws them down again as rain or dew 
when they are required. It bends the rays of the sun 
from their path, to give us the twilight of evening and 
of dawn; it disperses and refracts their various tints to 
beautify the approach and the retreat of the orb of day. 
But for the atmosphere, sunshine would burst on us and 
fail us at once, and at once remove us from midnight 
darkness to the blaze of noon. We should have no twi- 
light to soften and beautify the landscape; no clouds to 
shade us from the scorching heat, but the bald earth, as 
it revolved on its axis, would turn its tanned and weak- 
ened front to the full and unmitigated rays of the lord 
of day. It affords the gas which vivifies and warms our 
frames, and receives into itself that which has been pol- 
luted by use, and is thrown off as noxious. It feeds the 
flame of life exactly as it-does that of the fire—it is in 
both cases consumed, and affords the food of consumption 
—in both cases it becomes combined with charcoal, which 
requires it for combustion, and is removed by it when 
this is over.” 

“Tt is only the girdling encircling air,” says another § 114 
philosopher,* “that flows above and around all, that 


* Vide North British Review. 


64 THE PHYSICAL GEOGRAPHY OF THE SEA. 


CHAPTER makes the whole world kin. The earbonic acid with 
III. 


Its use to 
the whole 
world. 


§ 115 


which to-day our breathing fills the air, to-morrow seeks 
its way round the world. The date-trees that grow 
round the falls of the Nile will drink it in by their leaves ; 
the cedars of Lebanon will take of it to add to their 
stature ; the cocoa-nuts of Tahiti will grow rapidly upon 
it, and the palms and bananas of Japan will change it 
into flowers. The oxygen we are breathing was distilled 
for us some short time ago by the magnolias of the Sus- 
quehanna, and the great trees that skirt the Orinoco and 
the Amazon—the giant rhododendrons of the Himalayas 
contributed to it, and the roses and myrtles of Cashmere. 
the cinnamon-tree of Ceylon, and the forest older than 
the flood, buried deep in the heart of Africa, far behind 
the Mountains of the Moon. The rain we see descending 
was thawed for us out of the icebergs which have watched 
the polar star for ages, and the lotus lilies have soaked 
up from the Nile, and exhaled as vapour, snows that 
rested on the summits of the Alps.” 

“The atmosphere,” continues Maun, “which forms the 


As ae of outer surface of the habitable world, is a vast reservoir, 
anh 


€ 116 


into which the supply of food designed for living creatures 
is thrown; or, in one word, it is itself the food, in its 
simpie form, of all living creatures. The animal grinds 
down the fibre and the tissue of the plant, or the nutri- 
tious store that has been laid up within its cells, and 
converts these into the substance of which its own organs 
are composed. The plant acquires the organs and nutri- 
tious store thus yielded up as food to the animal, from 
the invulnerable air surrounding it.” 

“But animals are furnished with the means of loco 


THE ATMOSPHERE. 65 


motion and of seizure—they can approach their food, and 
lay hold of and swallow it; plants must wait till their 
food comes to them. No solid particles find access to 
their frames; the restless ambient air which rushes past 
them loaded with the carbon, the hydrogen, the oxygen, 
the water—everything they need in the shape of supplies, 
is constantly at hand to minister to their wants, not only 
to afford them food in due season, but in the shape and 
fashion in which alone it can avail them.” 


CHAPTER 
III. 


Of plants 


There is no employment more ennobling to man and g 117 


his intellect than to trace the evidences of design and 
purpose in the Creator, which are visible in many parts 


of the creation. Hence, to the right-minded mariner, General 


and to him who studies the physical relations of earth, 
sea, and air, the atmosphere is something more than a 
shoreless ocean, at the bottom of which he creeps along. 
It is an envelope or covering for the dispersion of light 
-and heat over the surface of the earth; it is a sewer into 
which, with every breath we draw, we cast vast quantities 
of dead animal matter ; it is a laboratory for purification, 
in which that matter is recompounded, and wrought 
again into wholesome and healthful shapes ; it is a machine 
for pumping up all the rivers from the sea, and conveying 
the waters for their fountains on the ocean to their 
sources in the mountains ; it is an inexhaustible magazine, 
marvellously adapted for many benign and_ beneficent 
purposes. 

Upon the proper working of this machine depends the 
well-being of every plant and animal that inhabits the 
earth ; therefore the management of it, its movements, 
and the performance of its offices, cannot be left to 


—— ee 


uses. 


§ 118 


CHAPTER 
II. 


§ 119 


Order in 
sea and air 


g 120 


Language 
of Nature. 


66 THE PHYSICAL GEOGRAPHY OF THE SEA. 


chance. They are, we may rely upon it, guided by laws 
that make all parts, functions, and movements of the 
machinery as obedient to order and as harmonious as ate 
the planets in their orbits. 

An examination into the economy of the universe will 
be sufficient to satisfy the well-balanced minds of obsery- 
ant men, that the laws which govern the atmosphere and 
the laws which govern the ocean’ are laws which were 
put in force by the Creator when the foundations of the 
earth were laid, and that therefore they are laws of order ; 
else, why should the Gulf Stream, for instance, be always 
where it is, and running from the Gulf of Mexico, and 
not somewhere else, and sometimes running into it? 
Why should there be a perpetual drought in one part of 
the world, and continual showers in another? Or why 
should the winds and “ waves of the sea ever clap their 
hands with joy,” or obey the voice of rebuke ? 

To one who looks abroad to contemplate the agents of 
nature, as he sees them at work upon our planet, no ex- 
pression uttered nor act performed by them is without 
meaning. By such an one, the wind and rain, the va- 
pour and the cloud, the tide, the current, the saltness, 
and depth, and warmth, and colour of the sea, the shade 
of the sky, the temperature of the air, the tint and shape 
of the clouds, the height of the tree on the shore, the 
size of its leaves, the brilliancy of its flowers—each and 
all may be regarded as the exponent of certain physical 
combinations, and therefore as the expression in which 
Nature chooses to announce her own doings, or, if we 
please, as the language in which she writes down or 
chooses to make known her own laws. To understand 


2 § 76. 


THE ATMOSPHERE. 67 


that language and to interpret aright those laws is the cnaprne 
object of the undertaking which we now have in hand. —— 
No fact gathered in such a field as the one before us can 
therefore come amiss to those who tread the walks of 
inductive philosophy ; for, in the hand-book of nature, 
every such fact is a syllable; and it is by patiently col- 
lecting fact after fact, and by joining together syllable 
after syllable, that we may finally seek to read aright 
from the great volume which the mariner at sea as well 

as the philosopher on the mountain each sees spread out 
before him. 

OF ITS CIRCULATION.—We have seen’ that there are § 121 
constant currents in the ocean; we shall now see that 
there are also regular currents in the atmosphere. 

From the parallel of about 30° north and south, nearly g 122 
to the equator, we have, extending entirely around the The trace. 
earth, two zones of perpetual winds, namely, the zone of 
north-east trades on this side, and of south-east on that. 
With slight interruptions, they blow perpetually, and are 
as steady and as constant as the currents of the Mississippi 
River, always moving in the same direction (Plate 1.) 
except when they are turned aside by a desert here and 
there to blow as monsoons, or as land and sea _ breezes. 

As these two main currents of air are constantly flowing 
from the poles toward the equator, we are safe in assum- 
ing that the air which they keep in motion must return 
by some channel to the place toward the poles whence it 
came in order to supply the trades. If this were not so, 
these winds would soon exhaust the Polar regions of 
atmosphere, and pile it up about the equator, and then 
cease to blow for the want of air to make more wind of. 


19g 31. 


CHAPTER 
III. 


§ 123 


Their 
currents. 


§ 124 


Cause of 
north-east 
wind. 


§ 125 


Tlustra- 
tion. 


68 THE PHYSICAL GEOGRAPHY OF THE SEA. 


This return current, therefore, must be in the upper 
regions of the atmosphere, at least until it passes over 
those parallels between which the trade-winds are always 
blowing on the surface. The return current must also 
move in the direction opposite to that wind the place of 
which it is intended to supply. These direct and counter 
currents are also made to move in a sort of spiral or loxo- 
dromic curve, turning to the west as they go from the 
poles to the equator, and in the opposite direction as they 
move from the equator toward the poles. This turning is 
caused by the rotation of the earth on its axis. 

The earth, we know, moves from west to east. Now, 
if we imagine a particle of atmosphere at the north pole, 
where it is at rest, to be put in motion in a straight line 
toward the equator, we can easily see how this particle of 
air, coming from the very axis of diurnal rotation, where 
it did not partake of the diurnal motion of the earth, 
would, in consequence of its vis inertia, find, as it travels 
south, the earth slipping from under it, as it were, and 
thus it would appear to be coming from the north-east 
and going toward the south-west; in other words, it would 
be a north-east wind. 

The better to explain, let us take a common terrestrial 
globe for the illustration. Bring the island of Madeira, 
or any other place about the same parallel, under the 
brazen meridian ; put a finger of the left hand on the 
place; then, moving the finger down along the meridian 
to the south, to represent the particle of air, turn the globe 
on its axis from west to east, to represent the diurnal 
rotation of the earth, and when the finger reaches the 
equator, stop. It will now be seen that the place on the 


THE ATMOSPHERE. 69 


globe under the finger is to the southward and westward BEE 
of the place from which the finger started ; in other words, — 
the track of the finger over the surface of the globe, like 

the track of the particle of air upon the earth, has been 

from the northward and eastward. 

On the other hand, we can perceive how a like particle § 126 
of atmosphere that starts from the equator, to take the CaO 
place of the other at the pole, would, as it travels north, wina. 
in consequence of its vis inertie, be going toward the east 
faster than the earth. It would therefore appear to be 
blowing from the south-west, and going toward the north- 
east, and exactly in the opposite direction to the other. 
Writing south for north, the same takes place between the 
south pole and the equator. 

Such is the process which is actually going on in nature; § 127 
and if we take the motions of these two particles as the TWO eos 
type of the motion of all, we shall have an illustration curents 
of the great currents in the air, the equator being near 
one of the nodes, and there being at least two systems of 
currents, an upper and an under, between it and each 
pole. 

Halley, in his theory of the trade-winds, pointed out § 128 
the key to the explanation so far, of the atmospherical Hattey's 
circulation ; but, were the explanation to rest here, a eiieaive 
north-east trade-wind extending from the pole to the 
equator would satisfy it; and were this so, we should 
have, on the surface, no winds but the north-east trade- 
winds on this side, and none but south-east trade-winds 
on the other side, of the equator. 

Let us return now to our northern particle (Plate I.), § 129 
and follow it in a round from the north pole across the Theory. 


70 THE PHYSICAL GEOGRAPHY OF THE SEA. 


cuaprer equator to the south pole, and back again. Setting off 
from the polar regions, this particle of air, for some rea- 
son which does not appear to have been very satisfac- 
torily explained by philosophers, instead of travelling’ on 
the surface all the way from the pole to the equator, 
travels in the upper regions of the atmosphere until it 
gets near the parallel of 30°. Here it meets, also in the 
clouds, the hypothetical particle that is coming from the 

south, and going north to take its place. 

§130 About this parallel of 30° north, then, these two par- 
Cause of ticles press against each other with the whole amount of 
~ their motive power, and produce a calm and an accumu- 

lation of atmosphere: this accumulation is sufficient to 
balance the pressure of the two winds from the north and 
south. 

§151 From under this bank of calms, which seamen call the 
pata 5“ horse lattitudes” (I have called them the calms of 

Cancer), two surface currents of wind are ejected; one 
toward the equator, as the north-east trades, the other 
toward the pole, as the south-west passage-winds. 

$132 These winds come out at the lower surface of the calm 
Pownward region, and consequently the place of the air borne away 

in this manner must be supplied, we may infer, by down- 
ward currents from the superincumbent air of the calm 
region, Like the case of a vessel of water which has 
two streams from opposite directions running in at the 
top, and two of equal capacity discharging in opposite 
directions at the bottom, the motion of the water would 
be downward, so is the motion of the air in this calm 
zone, 


§133 The barometer, in this calm region, is said to stand 


1 § 128 


THE ATMOSPHERE. v1 


higher than it does either to the north or to the south of cnarrza 


it; and this is another proof as to the banking up here 
of the atmosphere, and pressure from its downward mo- 
tion. We can understand why there should be an up- 
rising of the air which the two systems of trade-winds 
pour into the equatorial calms. But when this air com- 
mences to flow toward the poles as an upper current, we 
cannot understand why it should not continue gradually 
to descend and turn back’ all the way from the equator 
to the poles, nor as far as investigation has gone, hag 
any explanation been suggested for the calm belts of the 
tropics ; nor can we tell why the upper currents should 
meet at one parallel in preference to another. But the 
fact of a meeting and a preference is certain. 

Following our imaginary particle of air, however, from 
the north across this calm belt of Cancer, we now feel it 
moving on the surface of the earth as the north-east 
trade-wind; and as such it continues, till it arrives near 
the equator, where it meets a like hypothetical particle, 
which, starting from the south at the same time the other 
started from the north pole, has blown as the south-east 
trade-wind. 

Here, at this equatorial place of meeting, there is an- 
other conflict of winds, and another calm region, for a 
north-east and south-east wind cannot blow at the same 
time in the same place. The two particles have been 
put in motion by the same power; they meet with equal 
force; and, therefore, at their place of meeting, are 
stopped in their course. Here, therefore, there is a calm 


belt. 
Warmed now by the heat of the sun, and pressed on 


1 § 144, 


Ill. 


Effect of 
ealm 
region on 
barometer. 


Causes not 
under- 
stood. 


$134 


Theory 
continued 


$135 


Cause of 
calm. 


$ 136 


v2 THE PHYSICAL GEOGRAPHY OF THE-SEA. 


cuarter each side by the whole force of the north-east and south- 
III. 


east trades, these two hypothetical particles, taken as the 
tae type of the whole, cease to move onward and ascend. 
This operation is the reverse of that which took place at 
the méeting’ near the parallel of 30°. 
$137 This imaginary particle, then, having ascended to the 
Calm of upper regions of the atmosphere again, travels there coun- 
Capricom. | or to the south-east trades, until it meets, near the calm 
belt of Capricorn, another particle from the south pole ; 
here there is a descent as before; it then’ flows on toward 
the south pole as a surface wind from the north-west. 
§138 Entering the polar regions obliquely, it is pressed upon 
Conclusion by similar particles flowing in oblique currents across 
as every meridian ; and here again is a calm place or node ; 
for, as our imaginary particle approaches the parallels 
near the polar calms more and more obliquely, it, with 
all the rest, is whirled about the pole in a continued 
circular gale; finally, reaching the vortex or the calm 
place, it is carried upward to the regions of atmosphere 
above, whence it commences again its circuit to the north 
as an upper current, as far as the calm belt of Capricorn; 
here it encounters’ its fellow from the north ;° they stop, 
descend, and flow out as surface currents,’ the one with 
which the imagination is travelling, to the equatorial 
calm as the south-east trade-wind ; here’ it ascends, tra- 
velling thence to the calm belt of Cancer as an upper 
current counter to the north-east trades. Here*it ceases 
to be an upper current, but, descending,” travels on with 
the south-west passage-winds toward the pole. 
s 139 Now the course we have imagined an atom of air to 


take is this (Plate I.): an ascent in a place of calms 


§ 126. 5 § 126. 7 § 135. ° § 131. 
$1 6s] 2g 13 


THE ATMOSPHERE. 13 


about the north pole at P; an efflux thence as an upper cHarrns 
III. 


current’ until it meets G (also an upper current) over the 
2 . Course 
calms of Cancer. Here*there is supposed to be a descent, of the 
. 3 imaginary 
as shown by the arrows along the wavy lines which en- atom ot 
velop the circle. This upper current from the pole’ now 


becomes the north-east trade-wind, B, on the surface, 


air. 


until it meets the south-east trades in the equatorial 
calms, when it ascends and travels as C with the upper 
current to the calms of Capricorn, then as D with the 
prevailing north-west surface current to the south pole, 
thence up with the arrow P, and around with the hands 
of a watch, and back, as indicated by the arrows along 
Ee, G, and H, 

The Bible frequently makes allusions to the laws of § 140 
nature, their operation and effects. But such allusions a 
are often so wrapped in the folds of the peculiar and to laws of 
eraceful drapery with which its language is occasionally 
clothed, that the meaning, though peeping out from its 
thin covering all the while, yet lies in some sense con- 
cealed, until the lights and revelations of science are 
thrown upon it; then it bursts out and strikes us with 
exquisite force and beauty. 

As our knowledge of nature and her laws has in- § 141 
creased, so has our understanding of many passages in Lites 
the Bible been improved. The Psalmist called the earth the sivie 
“the round world;” yet for ages it was the most dam- Donates 
nable heresy for Christian men to say the world is round; Was 
and, finally, sailors circumnavigated the globe, proved the 
Bible to be right, and saved Christian men of science 
from the stake. 


“Canst thou tell the sweet influences of the Pleiades?” g 142 


1 § 129, 2 § 130. 8 § 124, * § 134, 


CHAPTER 
Ill. 


Remarks 
on the 
Pleiaces. 


§ 143 
The Bible 
in refer- 
ence to 
winds. 


§ 144 


“Slough- 


ing off” of 


winds on 
approach- 
ing the 
poles. 


§ 145 


Trade- 
winds 
on the 
Atlantic 


74 THE PHYSICAL GEOGRAPHY OF THE SEA. 


Astronomers of the present day, if they have not an- 
swered this question, have thrown so much light upon it 
as to show that, if ever it be answered by man, he must 
consult the science of astronomy. It has been recently 
all but proved, that the earth and sun, with their splendid 
retinue of comets, satellites, and planets, are all in motion 
around some point or centre of attraction inconceivably 
remote, and that that point is in the direction of the 
star Aleyon, one of the Pleiades! Who but the astrono- 
mer, then, could tell their “ sweet influences 2” 

And as for the general system of atmospherical circu- 
lation which I have been so long endeavouring to de- 
scribe, the Bible tells it all in a single sentence: “The 
wind goeth toward the south, and turneth about unto 
the north ; it whirleth about continually, and the wind 
returneth again according to his circuits.”—Eccl. i. 6. 

Of course, as the surface winds H and D (Plate 1) 
approach the poles, there must be a sloughing off, if I 
may be allowed the expression, of air from the surface 
winds, in consequence of their approaching the poles; 
for as they near the poles, the parallels become smaller 
and smaller, and the surface current must either extend 
much higher up, and blow with greater rapidity as it 
approaches the poles, or else a part of it must be sloughed 
off above, and so turn back before reaching the calms 
about the poles. The latter is probably the case. 

Our investigations show that the south-east trade-wind 
region is much larger than the north-east (I speak now 
of its extent over the Atlantic Ocean only); that the 
south-east trades are the fresher, and that they often 
push themselves up to 10° or 15° of north latitude ; 


THE ATMOSPHERE. 75 


whereas the north-east trade-wind seldom gets south of cnaprer 
the equator. ina 

The peculiar clouds of the trade-winds are formed be- § 146 
tween the upper and lower currents of air. They are Cloaaesof 
probably formed of vapour condensed from the upper winas. 
current, and evaporated as it descends by the lower and 
dry current from the poles. It is the same phenomenon 
up there which is so often observed here below; when a 
cool and dry current of air meets a warm and wet one, 
an evolution of vapour or fog ensues. 

We now see the general course of the “wind in his ¢ 147 
circuits,” as we see the general course of the water in a Genera! 
river. There are many abrading surfaces, irregularities, winds” 
&e., which produce a thousand eddies in the main stream; 
yet, nevertheless, the general direction of the whole is 
not disturbed nor affected by those counter currents ; so 
with the atmosphere and the variable winds which we 
find here in this latitude. 

Have I not, therefore, very good grounds for the § 148 
opinion’ that the “wind in his circuits,’ though appa- ObeRtent 
rently to us never so wayward, is as obedient to law and 
as subservient to order as were the morning stars when 
they “sang together?” 

There are at least two forces concerned in driving the § 149 
wind through its circuits. We have seen” whence that two forces 
force is derived which gives easting to the winds as they ante 
approach the equator, and westing as they approach the ae 
poles, and allusion, without explanation, has been made” 
to the source whence they derive their northing and their 
southing.- The trade-winds are caused, it is said, by the crue 


inter-tropical heat of the sun, which, expanding the air, winds con- 
sidered 


1 § 118. a § 124, $ § 186, 


CHA!'TER 
Hil. 


— 


§ 150 


Tilustra- 
tion. 


76 THE PHYSICAL GEOGRAPHY OF THE SEA. 


causes it to rise up near the equator; it then flows off in 
the upper currents north and south, and there is a rush 


of air at the surface both from the north and the south 
to restore the equilibrium—hence the trade-winds. But 
to the north side of the trade-wind belt in the northern, 
and on the south side in the southern hemisphere, the 
prevailing direction of the winds is not toward the source 
of heat about the equator, but exactly in the opposite 
direction. In the extra-tropical region of each hemis- 
phere the prevailing winds blow from the equator toward 
the poles. It therefore at first appears paradoxical to 
say that heat makes the easterly winds of the tornd 
zone blow toward the equator, and the westerly winds of 
the temperate zones to blow toward the poles. Let us 
illustrate : 

The primum mobile of the extra-tropical winds toward 
the equator is, as just intimated, generally ascribed to 
heat, and in this wise, namely: Suppose, for the moment, 
the earth to have no diurnal rotation ; that it is at rest ; 
that the rays of the sun have been cut off from it; that 
the atmosphere has assumed a mean uniformity of tem- 
perature, the thermometer at the equator and the ther- 
mometer at the poles giving the same reading; that the 
winds are still, and that the whole aerial ocean is in 
equilibrium and at rest. Now imagine the screen which 
is supposed to have shut off the influence of the sun to 
be removed, and the whole atmosphere to assume the 
various temperatures in the various parts of the world 
that it actually has at this moment, what would take 
place, supposing the uniform temperature to be a mean 
between that at the equator and that at the poles? 


THE ATMOSPHERE. Oa 


Why, this would take place: a swelling up of the atmos- cus 
phere about the equator by the expansive force of inter- — 
tropical heat, and a contraction of it about the poles in 
consequence of the cold. These two forces, considering 
them under their most obvious effects, would disturb the 
supposed atmospherical equilibrium by altering the level 

of the great aerial ocean; the expansive force of heat 
elevating it about the equator, and the contracting powers 

of cold depressing it about the poles. And forthwith two 
systems of winds would commence to blow, namely, one in 

the upper regions from the equator toward the poles, and 

as this warm and expanded air should flow toward either 

pole, seeking its level, a wind would blow on the surface 

from either pole to restore the air to the equator which 

the upper current had carried off. 

These two winds would blow due north and south; § 151 
the effects of heat at the equator, and cold at the poles, taste 
would cause them so to do. Now suppose the earth to tinuea 
commence its diurnal rotation ; then, instead of having 
these winds north and south winds, they will, for reasons 
already explained,’ approach the equator on both sides 
with easting in them, and each pole with westing. 

The circumference of the earth measured on the g 152 
parallel of 60° is only half what it is when measured on 
the equator. Therefore, supposing velocity to be the 
same, only half the volume of atmosphere’ that sets off 
from the equator as an upper current toward the poles 
can cross the parallel of 60° north or south, The other 
moiety has been gradually drawn in and carried back’ 
by the current which is moving in the opposite direction. 

Such, and such only, would be the extent of the power § 153 


1 § 124, 2 § 149, 2 § 144, 


CHAPTER 
Ill. 


Power of 
sun on the 
air under 
supposed 
circum- 
stances, 


Specific 
gravity of 
air. 


§ 154 


Con- 
clusions. 


78 THE PHYSICAL GEOGRAPHY OF THE SEA. 


of the sun to create a polar and equatorial flow of air, 
were its power confined simply to a change of level But 
the atmosphere has been invested with another property 
which increases its mobility, and gives the heat of the 
sun still more power to put it in motion, and it is this: 
as heat changes the atmospherical level, it changes also 
the specific gravity of the air acted upon. If, therefore, 
the level of the great aerial ocean were undisturbed by 
the sun’s rays, and if the air were adapted to a change 
of specific gravity alone, without any change in volume, 
this quality would also be the source of at least two 
systems of currents in the air, namely, an upper and a 
lower. The two agents combined, namely, that which 
changes level or volume, and that which changes specific 
gravity, give us the general currents under consideration. 
Hence we say that the primum mobile of the air is 
derived from change of specific gravity duced by the 
freezing temperature of the polar regions, as well as from 
change of specific gravity due the expanding force of the 
sun’s rays within the tropics. 

Therefore, fairly to appreciate the extent of the influence 
due the heat of the sun in causing the winds, it should be 
recollected that we may with as much reason ascribe to 
the inter-tropical heat of the sun the north-west winds, 
which are the prevailing winds of the extra-tropical 
regions of the southern hemisphere, or the south-west 
winds, which are the prevailing winds of the extra-tropical 
regions of the northern hemisphere, as we may the trade- 
winds, which blow in the opposite directions. Paradoxi- 
cal, therefore, as it seems for us to say that the heat of 
the sun causes the winds between the parallels of 25° or 


THE ATMOSPHERE. 79 


80° north and south to blow toward the equator, and 
that it also causes the prevailing winds on the polar sides 
of these same parallels to blow toward the poles, yet the 
paradox ceases when we come to recollect that by the 
process of equatorial heating and polar cooling which is 
going on in the atmosphere, the specific gravity of the air 
is changed as well as its level, Nevertheless, as Halley 
said, in his paper read before the Royal Society in London 
in 1686, and as we also have said} “it is likewise very 
hard to conceive why the limits of the trade-wind should 
be fixed about the parallel of latitude 30° all around the 
globe, and that they should so seldom exceed or fall short 
of those bounds.” 

Operated upon by the equilibrating tendency of the 
atmosphere and by diurnal rotation, the wind approaches 
the north pole, for example, by a series of spirals from the 
south-west. If we draw a circle about this pole on a 
common terrestrial globe, and intersect it by spirals to 
represent the direction of the wind, we shall see that the 
wind enters all parts of this circle from the south-west, 
and that, consequently, there should be about the poles a 
dise or circular space of calms, in which the air ceases to 
move forward as wind, and ascends as in a calm; about 
this calm disc, therefore, there should be a whirl, in which 
the ascending column of air revolves from right to left, 
or against the hands of a watch. At the south pole the 
winds come from the north-west, and consequently there 
they revolve about it with the hands of a watch. 

That this should be so will be obvious to any one who 
will look at the arrows on the polar sides of the calms 
Cancer and Capricorn (Plate I.) These arrows are 


1 § 133. 2 § 187. 


CHAPTER 
Ill. 


Halley's 
remarks. 


§ 155 


How 
wind ap- 
proaches 
north 
pole. 


South pole 


80 THE PHYSICAL GEOGRAPHY OF THE SEA. 


cnaprer intended to represent the prevailing direction of the wind 
“at the surface of the earth on the polar side of these calms. 
$156 It is a singular coincidence between these two facts 
Brews thus deduced, and other facts which have been observed 


enceree and which have been set forth by Redfield, Reid, Pidding- 


se ton, and others, namely, that many of the rotatory storms 
‘uit in the northern hemisphere revolve as do the whirlwinds 
mes about the north pole, namely, from right to left, and that 
all circular gales in the southern hemisphere revolve in the 
opposite direction, as does the whirl about the south pole. 

§157 How can there be any connection between the rotary 
motion of the wind about the pole, and the rotary motion 
of it in a gale caused here by local agents ? 

§158 That there is probably such a connection has been 
suggested by other facts and circumstances, and perhaps I 
shall be enabled to make myself clearer when we come to 
treat of these facts and circumstances, and to inquire 
farther' into the relations between magnetism and the 

Heat not circulation of the atmosphere; for, although the theory 


the sole 


eeent of of heat satisfies the conditions of the problem, and though 
heat, doubtless, is one of the chief agents in keeping up 
the circulation of the atmosphere, yet it can be made to 
appear that it is not the sole agent. 

§159 Some oF ITS METEOROLOGICAL AGENCIES.—So far, we 
pees of see how the atmosphere moves; but the atmosphere, like 
sphere every other department in the economy of nature, has its 

offices to perform, and they are many. I have already 
alluded to some of them; but I only propose, at this 
time, to consider some of the meteorological agencies at 
sea, which, in the grand design of creation, have probably 


been assigned to this wonderful machine. 


1 As at § 299, 


THE ATMOSPHERE. ro | 


To distribute moisture over the surface of the earth, 
and to temper the climate of different latitudes, it would 
seem, are two great offices assigned by their Creator to 
the ocean and the air. 

When the north-east and south-east trades meet and 
produce the equatorial calms,’ the air, by the time it 
reaches this calm belt, is heavily laden with moisture, for 
in each hemisphere it has travelled obliquely over a large 
space of the ocean. It has no room for escape but in the 
upward direction.” It expands as it ascends, and becomes 
cooler; a portion of its vapour is thus condensed, and 
comes down in the shape of rain. Therefore it is that, 
under these calms, we have a region of constant precipita- 
tion. Old sailors tell us of such dead calms of long con- 
tinuance here, of such heavy and constant rains, that they 
have scooped up fresh water from the surface of the sea. 

The conditions to which this air is exposed here under 
the equator are probably not such as to cause it to preci- 
pitate all the moisture that it has taken up in its long 
sweep across the waters. Let us see what becomes of the 
rest ; for Nature, in her economy, permits nothing to be 
taken away from the earth which is not to be restored 
to it again in some form, and at some time or other. 

Consider the great rivers—the Amazon and the Missis- 
sippi, for example. We see them day after day, and 
year after year, discharging immense volumes of water 
into the ocean, 

“ All the rivers run into the sea, yet the sea is not full” 
(Eccl. 1. 7). Where do the waters so discharged go, and 
where do they come from ? They come from their sources, 
you will say. But whence are their sources supplied ? for, 


7 § 135. a § 136. 


CHAPTER 
III. 


$ 160 
On mois- 
ture and 
climate. 


§ 161 


Constant 
precipita- 
tion in 
calm belts 


Singwar 
fact. 


§ 162 


§ 163 


Amazon 
and Missis+ 
sippL 


Whence 
are their 
sources 

supplied 


82 THE PHYSICAL GEOGRAPHY OF THE SEA. 


cnapter unless what the fountain sends forth be returned to it 
saute again, it will fail and be dry. 

§164 We see simply, in the waters that are discharged by 
Brecipitae these rivers, the amount by which the precipitation exceeds 
ceeds eva- the evaporation throughout the whole extent of valley 
ee drained by them ; and by precipitation I mean the total 

amount of water that falls from, or is deposited by the 
atmosphere, whether as dew, rain, hail, or snow. 

$165 The springs of these rivers' are supplied from the rains 

of heaven, and these rains are formed of vapours which 
are taken up from the sea, that “it be not full,” and 
carried up to the mountains through the air. 

“Note the place whence the rivers come, thither they 
return again.” 

$166 Behold how the waters of the Amazon, of the Mississippi, 
Waters of the St. Lawrence, and all the great rivers of America, 


rivers car- 


ried back Europe, and Asia, lifted up by the atmosphere, and 
el flowing in invisible streams back through the air to their 
sources among the hills,* and that through channels so 
regular, certain, and well defined, that the quantity thus 
conveyed one year with the other is nearly the same: 
for that is the quantity which we see running down to 
the ocean through these rivers ; and the quantity discharged 
annually by each river is, as far as we can judge, nearly 

a constant. 
§167 We now begin to conceive what a powerful machine 
Order and the atmosphere must be; and, though it is apparently so 


arrange- in pee : A 

mentin Gapricious and wayward in its movements, here is evidence 

the offices : . 

ofamo- Of order and arrangement which we must admit, and 

where : - . : . 
proof which we cannot aeny, that it performs this mighty 


office with regularity and certainty, and is, therefore, as 


1 § 112, 2 $112. 


THE ATMOSPHERE. 83 


obedient to law as is the steam-engine to the will of its 
builder. 

It, too, is an engine. The South Seas themselves, in 
all their vast inter-tropical extent, are the boiler for it, 
and the northern hemisphere is its condenser. The 
mechanical power exerted by the air and the sun in lift- 
ing water from the earth, in transporting it from one 
place to another, and in letting it down again, is incon- 
ceivably great. The utilitarian who compares the water- 
power that the Falls of Niagara would afford if applied 
to machinery, is astonished at the number of figures 
which are required to express its equivalent in horse-power. 
Yet what is the horse-power of the Niagara, falling a few 
steps, in comparison with the horse-power that is required 
to lift up as high as the clouds and let down again all 
the water that is discharged into the sea, not only by this 
river, but by all other rivers in the world. The cal- 
culation has been made by engineers, and, according to it, 
the force for making and lifting vapour from each area of 
one acre that is included on the surface of the earth is 
equal to the power of 30 horses, and for the whole area 
of the earth it is 800 times greater than all the water- 
power in Europe. 

Where does the vapour that makes the rains which 
feed the rivers of the northern hemisphere come from ? 

The proportion between the land and water in the 
northern hemisphere is very different from the proportion 
that obtains between them in the southern. In the 
northern hemisphere, the land and water are nearly equally 
divided. In the southern, there is several times more 
water than land. All the great rivers in the world are 


CHAPTER 
Il. 


§ 168 


Compari- 
son with 
the steam 
engine. 


Calcula- 
tion of 
force re- 
quired for 
lifting va- 
pour from 
the earth. 


§ 169 


Difference 
of propor- 
tion be- 
tween land 
and water 
in north- 
ern and 
southern 
hemi- 
spheres. 


84 THE PHYSICAL GEOGRAPHY OF THE SEA. 


cuartex in the northern hemisphere, where there is less ocean to 
ke supply them. Whence, then, are their sources replenished? 
ver Those of the Amazon are supplied with rains from the 
equatorial calms and trade-winds of the Atlantic. That 

river runs east, its branches come from the north and south ; 

it is always the rainy season on one side or the other of it ; 
consequently, it is a river without periodic stages of a 

very marked character. It is always near its high-water 

mark. For one half of the year its northern tributaries 

are flooded, and its southern for the other half. It dis- 
charges under the line, and as its tributaries come from 

both hemispheres, it cannot be said to belong exclusively 

to either. It is supplied with water made of vapour 

that is taken up from the Atlantic Ocean. Taking the 

Riodela Amazon, therefore, out of the count, the Rio de la Plata 


Platathe , 7 " 3 
only great is the only great river of the southern hemisphere. There is 


Baile 0 large river in New Holland. The South Sea Islands 
ate give rise to none, nor is there one in South Africa entitled 
to be called great that we know of. 
s1790 The great rivers of North America and North Africa, 
and all the rivers of Europe and Asia, lie wholly within 
the northern hemisphere. How is it, then, considering 
that the evaporating surface les mainly in the southern 
hemisphere—how is it, I say, that we should have the 
evaporation to take place in one hemisphere and the con- 
Greater ensation in the other? The total amount of rain which 
sews. falls in the northern hemisphere is much greater, meteorol- 
citem. ogists tell us, than that which falls in the southern, The 
speve 12 annual amount of rain in the north temperate zone is 
half as much again as that of the south temperate. 


:171  Howis it, then, that this vapour gets, as stated; from the 


2 § 170. 


THE ATMOSPHERE. 85 


southern into the northern hemisphere, and comes with 
such regularity that our rivers never go dry and our 
springs fail not? It is because of the beautiful operations 
and the exquisite compensation of this grand machine, 
the atmosphere. It is exquisitely and wonderfully coun- 
terpoised. Late in the autumn of the north, throughout 
its winter, and in early spring, the sun is pouring his rays 
with the greatest intensity down upon the seas of the 
southern hemisphere, and tnis powerful engine which we 
are contemplating is pumping up the water there’ for our 
rivers with the greatest activity. At this time, the mean 
temperature of the entire southern hemisphere is said to 
be about 10° higher than the northern. 

The heat which this heavy evaporation absorbs becomes 
latent, and, with the moisture, is carried through the 
upper regions of the atmosphere until it reaches our climates. 
Here the vapour is formed into clouds, condensed, and 
precipitated. The heat which held this water in the 
state of vapour is set free, it becomes sensible heat, and 
it is that which contributes so much to temper our winter 
climate. It clouds up in winter, turns warm, and we say 
we are going to have falling weather. That is because 
the process of condensation has already commenced, 
though no rain or snow may have fallen: thus we feel 
this southern heat that has been collected from the rays 
of the sun by the sea, been bottled away by the winds 
im the clouds of a southern summer, and set free in the 
process of condensation in our northern winter. 

If Plate I. fairly represent the course of the winds, 
the south-east {rade-winds would enter the northern hemi- 
sphere, and, as an upper current, bear into it all their 


1 § 169. 


CHAPTER 
III. 


How the 
atmo- 
sphere 
supplies 
the north- 
ern rivers 
from the 
southern 
seas. 


Process of 
condensa- 
tion. 


§ 173 
South-east 
trade- 
winds bear 
their mois- 
ture inta 
northern 
hemi- 
sphere. 


86 THE PHYSICAL GEOGRAPHY OF THE SEA. 


cuapTeR moisture, except that which is precipitated in the region of 
ees equatorial calms. 
$174 The South Seas, then, should supply mainly the water 
Pore for this engine, while the northern hemisphere condenses 
it; we should, therefore, have more rain in the northern 
hemisphere. The rivers tell us that we have—at least 
on the land: for the great water-courses of the globe, and 
half the fresh water in the world, are found on our side 
of the equator. This fact alone is strongly corroborative 
of this hypothesis. 
$175 The rain gauge tells us also the same story. The 
Confirmed yearly average of rain in the north temperate zone is, 
sae according to Johnston, thirty-seven inches. He gives 
but twenty-six in the south temperate. The observations 
of mariners are also corroborative of the same. Log- 
books, containing altogether the records for upward of 
260,000 days in the Atlantic Ocean north and south; 
have been carefully examined for the purpose of ascer- 
taining, for comparison, the number of calms, rains, and 
Result of gales, therein recorded for each hemisphere.  Propor- 
Eoidae: tionally the number of each is given as decidedly greater 
“eS for the north than it is for the south. The result of this 
examination is very instructive, for it shows the status 
of the atmosphere to be much more unstable in the 
northern hemisphere, with its excess of land, than in the 
southern, with its excess of water. Rains, and fogs, and 
thunder, and calms, and storms, all occur much more 
frequently, and are more irregular also as to the time 
and place of their occurrence on this side, than they are 
on the other side of the equator. 
$176 Moisture is never extracted from the air by subjecting 


1 According to § 168. 2 Plate XIII. 


THE ATMOSPHERE. S87 


it from a low to a higher temperature, but the reverse. cHarrex 
5 3 ° A Ill. 
Thus all the air which comes loaded with moisture from 


. . . . ° Moisture 

the other hemisphere, and is borne into this with tke never ex- 
F C1 5 tracted by 

south-east trade-winds, travels in the upper regions of the ujecting 


the air 


atmosphere’ until it reaches the calms of Cancer; here it from aiow 
becomes the surface wind that prevails from the south- eee 
ward and westward. As it goes north it grows cocler, “"° 
and the process of condensation commences. 

We may now liken it to the wet sponge, and the g 177 
decrease of temperature to the hand that squeezes that 
sponge. Finally reaching the cold latitudes, all the mois- 
ture that a dew-point of zero, and even far below, can 
extract, is wrung from it; and this air then commences 
“to return according to his circuits” as dry atmosphere. 

And here we can quote Scripture again: “ The north mportant 
wind driveth away rain.” ‘This is a meteorological fact tontealiae 
of high authority and great importance in the study of 

the circulation of the atmosphere. 

By reasoning in this manner and from such facts, we g 178 
are led to the conclusion that our rivers are supplied with conclusion 
their waters principally from the trade-wind regions, the ae 
extra-tropical northern rivers from the southern trades, 
and the extra-tropical southern rivers from the north- 
ern trade-winds, for the trade-winds are the evaporating 
winds. 

Taking for our guide such faint glimmerings of light § 179 
as we can catch from these facts, and supposing these saltest 

: F portion of 
views to be correct, then the saltest portion of the sea tne sea 
should be in the trade-wind regions, where the water for ee 
regions, 


all the rivers is evaporated ; and there the saltest portions 
are found. ‘There, too, the rains fall less frequently.” 


a § 130. 2 Plate XIII. 


58 THE PHYSICAL GEOGRAPHY OF THE SEA, 


exapteR Dr, Ruschenberger, of the navy, on his last voyage to 
Ill. : : 
— India, was kind enough to conduct a series of observa- 


§ 180 
Dr. Rusch- 


coverer'S narallel of 17° north and south—midway of the trade- 


eae wind regions—he found the heaviest water. Though so 
gravity of warm, the water there was heavier than the cold water 
to the south of the Cape of Good Hope. Lieutenant D. 
D. Porter, in the steam-ship Golden Age, found the 


heaviest water about the parallels of 20° north and 17° 


tions on the specific gravity of sea water. In about the 


south. 
§181 In summing up the evidence in favour of this view of 
How itis the general system of atmospherical circulation, it remains 


that there Cin, 8 e ° 
are small. to be shown how it is, if the view be correct, there should 
er rivers 


andless be smaller rivers and less rain in the southern hemisphere. 
rain in © C 
The winds that are to blow as the north-east trade-winds, 


southern 
hemi- 


spuere, returning from the polar regions, where the moisture’ has 


been compressed out of them, remain, as we have seen, 
dry winds until they cross the calm zone of Cancer, and 
are felt on the surface as the north-east trades. About 
two-thirds of them only can then blow over the ocean ; 
the rest blow over the land—over Asia, Africa, and North 
America, where there is but comparatively a small portion 
of evaporating surface exposed to their action. 

§182 The zone of the north-east trades extends, on an aver- 


Zoneof age, from about 29° north to 7° north. Now, if we 


tratewind examine the globe, to see how much of this zone is land 
and how much water, we shall find, commencing with 
China and coming over Asia, the broad part of Africa, 
and so on, across the continent of America to the Pacific, 
land enough to fill up, as nearly as may be, just one third 


of it. This land, if thrown into one body between these 


1 § 176, 


THE ATMOSPHERE. 89 


parallels, would make a belt equal to 120° of longitude 
by 22° of latitude, and comprise an area of about twelve 
and a half millions of square miles, thus leaving an eva- 
porating surface of about twenty-five millions of square 
miles in the northern against about seventy-five millions in 
the southern hemisphere. 

According to the hypothesis, illustrated by Plate L., 
as to the circulation of the atmosphere, it is these north- 
east trade-winds that take up and carry over, after they 
rise up in the belt of equatorial calms, the vapours which 
make the rains that feed the rivers in the extra-tropical 
regions of the southern hemisphere. 

Upon this supposition, then, two-thirds only of the 
north-east trade-winds are fully charged with moisture, 
and only two-thirds of the amount of rain that falls in the 
northern hemisphere should fall in the southern, and this 
is just about the proportion’ that observation gives. 

In like manner, the south-east trade-winds take up the 
vapours which make our rivers, and as they prevail to a 
much greater extent at sea, and have exposed to their 
action about three times as much ocean as the north-east 
trade-winds have, we might expect, according to this 


hypothesis, more rains in the northern—and consequently 
more and larger rivers—than in the southern hemisphere. 
That part of the ocean over which the south-east trades 
prevail is very much larger than that portion where the 
north-east trades blow. 

This estimate as to the quantity of rain in the two 
hemispheres is one which is not capable of verification by 
any more than the rudest approximations ; for the greater 


extent of south-east trades on one side, and of high moun- 


1 § 178, 


CHAPTER 
Ill. 


§ 184 


Only two- 
thirds fully 
charged 
with moi+ 
ture. 


§ 185 


South-east 
trade- 
winds pre- 
vailtoa 
greater 
extent at 
sea. 


§ 186 


Difficulty 
of estimat- 
ing the 
quantity of 
rain in the 
two hemi- 
spheres. 


CHAPTER 
III. 


§ 187 


§ 188 


Rainy 
seasons. 


§ 189 


In Oregon. 


§ 190 


System of 
zones fol- 
lows the 
sun. 


90 THE PHYSICAL GEOGRAPHY OF THE SEA. 


tains on the other, must each of necessity, and indepen- 
dent of other agents, have their effects. Nevertheless, 
this estimate gives as close an approximation as we can 
make out from our data. 

The rainy seasons, how caused.—The calm and trade- 
wind regions or belts move up and down the earth 
annually, in latitude nearly a thousand miles. In July 
and August, the zone of equatorial calms is found between 
7° north and 12° north, sometimes higher; in March and 
April, between latitude 5° south and 2° north. 

With this fact, and these points of view before us, it is 
easy to perceive why it is that we have a rainy season in 
Oregon, a rainy and dry season in California, another at 
Panama, two at Bogot&, none in Peru, and one in Chili. 

In Oregon it rains every month, but about five times 
more in the winter than in the summer months. 

The winter there is the summer of the southern hemi- 
sphere, when this steam-engine’is working with the great- 
est pressure. The vapour that is taken up by the south- 
east trades is borne along over the region of north-east 
trades to latitude 35° or 40° north, where it descends and 
appears on the surface with the south-west winds of those 
latitudes. Driving upon the highlands of the continent, 
this vapour is condensed and precipitated, during this 
part of the year, almost in constant showers, and to the 
depth of about thirty inches in three months. 

In the winter, the calm belt of Cancer approaches the 
equator. This whole system of zones, namely, of trades, 
calms, and westerly winds, follows the sun; and they of 
our hemisphere are nearer the equator in the winter and 
spring months than at any other season, 


TS SeLG8: 


THE ATMOSPHERE. 9] 


The south-west winds commence at this season to pre- 
vail as far down as the lower part of California. In 
winter and spring, the land in California is cooler than 
the sea air, and is quite cold enough to extract moisture 
from it. But in summer and autumn the land is the 
warmer, and cannot condense the vapours of water held 
by the air. So the same cause which made it rain in 
Oregon now makes it rain in California. As the sun 
returns to the north, he brings the calm belt of Cancer 
and the north-east trades along with him; and now, at 
places where, six months before, the south-west winds 
were the prevailing winds, the north-east trades are 
found to blow. This is the case in the latitude of Cali- 
fornia. The prevailing winds, then, instead of going 
from a warmer to a cooler climate, as before, are going 
the opposite way. Consequently, if, under these circum- 
stances, they have the moisture in them to make rains of, 
they cannot precipitate it. 

Proof, if proof were wanting, that the prevailing winds 
in the latitude of California are from the westward, is 
obvious to all who cross the Rocky Mountains or ascend 
the Sierra Madre. In the pass south of the Great Salt 
Lake basin those west winds have worn away the hills 
and polished the rock by their ceaseless abrasion and the 
scouring effects of the driving sand. Those who have 
crossed this pass are astonished at the force of the wind 
and the marks there exhibited of its GEOLOGICAL AGENCIES. 

Panama is in the region of equatorial calms. This belt 
of calms travels during the year, back and forth, over 
about 17° of latitude, coming farther north in the summer, 
where it tarries for several months, and then returning 


CHAPTER 
III. 


STS 


Rainy 
season in 
California, 


Cause, 


§ 192 


Proof that 
west winds 
prevail in 

California. 


§ 193 


Equatoriaj 
calms, 


CHAPTER 
IIT. 


Rainy 
season at 
Panama. 


Move- 
ments of 
the belt of 
calms. 


§ 194 


Rainless 
regions. 


92 THE PHYSICAL GEOGRAPHY OF THE SEA. 


so as to reach its extreme southern latitude some time in 
March or April. Where these calms are it is always 
raining, and the chart* shows that they hang over the 
latitude of Panama from June to November, consequently 
from June to November is the rainy season at Panama. 
The rest of the year that place is in the region of the 
north-east trades, which, before they arrive there, have 
to cross the mountains of the isthmus, on the cool tops of 
which they deposit their moisture, and leave Panama 
rainless and pleasant until the sun returns north with 
the belt of equatorial calms after him. They then push 
the belt of north-east trades farther to the north, occupy 
a part of the winter zone, and refresh that part of the 
earth with summer rains. This belt of calms moves over 
more than double of its breadth, and nearly the entire 
motion from south to north is accomplished generally in 
two months, May and June. ‘Take the parallel of 4° 
north as an illustration: during these two months the 
entire belt of calms crosses this parallel, and then leaves 
it in the region of the south-east trades. During these 
two months it was pouring down rain on that parallel. 
After the calm belt passes it, the rains cease, and the 
people in that latitude have no more wet weather till the 
fall, when the belt of calms recrosses this parallel on 
its way to the south. By examining the “ Trade-wind 
Chart,” it may be seen what the latitudes are that have 
two rainy seasons, and that Bogota is within the bi-rainy 
latitudes. 

The Rainless Regions.—The coast of Peru is within 
the region of perpetual south-east trade-winds. Though 


* Vide Trade-wind Chart (Maury’s Wind and Current). 


THE ATMOSPHERE. 93 


the Peruvian shores are on the verge of the great South cnapres 
Sea boiler, yet it never rains there. The reason is ine 
plain. 

The south-east trade-winds in the Atlantic Ocean first § 195 
strike the water on the coast of Africa. Travelling to suena 
the north-west, they blow obliquely across the ocean winas. 
until they reach the coast of Brazil. By this time they 
are heavily laden with vapour, which they continue to 
bear along across the continent, depositing it as they go, 
and supplying with it the sources of the Rio de la Plata 
and the southern tributaries of the Amazon. Finally, 
they reach the snow-capped Andes, and here is wrung 
from them the last particle of moisture that that very 
low temperature can extract. 

Reaching the summit of that range, they now tumble Peruvian 
down as cool and dry winds on the Pacific slopes beyond. ane 
Meeting with no evaporating surface, and with no tem- vehour 
perature colder than that to which they were subjected °7"""™ 
on the mountain-tops, they reach the ocean before they 
again become charged with fresh vapour, and before, 
therefore, they have any which the Peruvian climate can 
extract. The last they had to spare was deposited as 
snow on the tops of the Cordiileras, to feed mountain 
streams under the heat of the sun, and irrigate the val- 
leys on the western slopes. Thus we see how the top of 
the Andes becomes the reservoir from which are supplied 
the rivers of Chili and Peru. 

The other rainless or almost rainless regions are the § 196 
western coasts of Mexico, the deserts of Africa, Asia, oe 


North America, and Australia. regions. 
We have a rainless region about the Red Sea, because g 197 


CHAPTER 
DLs 


— 


§ 198 


Difference 
between 
Australia 
and South 
America. 


§ 199 


9 4 THE PHYSICAL GEOGRAPHY OF THE SEA. 


the Red Sea, for the most part, lies within the north-east 
trade-wind region, and these winds, when they reach that 
region, are dry winds, for they have as yet, in their 
course, crossed no wide sheets of water from which they 
could take up a supply of vapour. 

Most of New Holland lies within the south-east trade- 
wind region; so does most of inter-tropical South Ame- 
rica, But inter-tropical South America is the land of 
showers. The largest rivers, and most copiously watered 
country in the world are to be found there, whereas 
almost exactly the reverse is the case in Australia. 
Whence this difference? “Examine the direction of the 
winds with regard to the shore-line of these two regions, 
and the explanation will at once be suggested. In Aus- 
tralia—east coast—the shore-line is stretched out in the 
direction of the trades; in South America—east coast— 
it is perpendicular to their direction. In Australia, they 
fringe this shore only with their vapour, and so stint 
that thirsty land with showers that the trees cannot 
afford to spread their leaves out to the sun, for it evapo- 
rates all the moisture from them; their instincts, there- 
fore, teach them to turn their edges to his rays. In 
inter-tropical South America, the trade-winds blow per- 
pendicularly upon the shore, penetrating the very heart 
of the country with their moisture. Here the leaves, 
measuring many feet square 


as the plantain, &e.—turn 
their broad sides up to the sun, and court his rays. 

Why there is more rain on one side of a mountain than 
on the other. 

We may now, from what has been said, see why the 
Andes, and all other mountains which lie athwart the 


THE ATMOSPHERE. 95 


course of the winds, have a dry and a rainy side, and 
how the prevailing winds of the latitude determine which 
is the rainy and which the dry side. 

Thus, let us take the southern coast of Chili for illus- 
tration. In our summer time, when the sun comes north, 
and drags after him his belts of perpetual winds and 
calms, that coast is left within the regions of the north- 
west winds—the winds that are counter to the south- 
east trades—which, cooled by the winter temperature of 
the highlands of Chili, deposit their moisture copiously. 
During the rest of the year, the most of Chili is in the 
region of the south-east trades, and the same causes 
which operate in California to prevent rain there, operate 
in Chili; only the dry season in one place is the rainy 
season of the other. 

Hence we see that the weather side of all such moun- 
tains as the Andes is the wet side, and the lee side the 
dry. 


CHAPTER 
Ill. 


Reason 
why one 
side of a 
mountain 
is wet and 
the other 
dry. 


The same phenomenon, from a like cause, is repeated § 200 


in inter-tropical India, only in that country each side of 
the mountain is made alternately the wet and the dry 
side by a change in the prevailing direction of the wind. 


India is in one of the monsoon regions 2 it is the most India the 


most fam- 


famous of them all From October to April the north- ons ofthe 


monsoon 


east trades prevail. - They evaporate from the Bay of regions. 


Bengal water enough to feed with rains, during this sea- 
son, the western shores of this bay and the Ghauts range 
of mountains. This range holds the relation to these 
winds that the Andes of Peru’ hold to the south-east 
trades ; it first cools and then relieves them of their 
moisture, and they tumble down on the western slopes 


1 Plate WILL. 2 § 194. 


CHAPTER 
III. 


§ 201 


How the 
south-east 
trades in 
certain 
parts of the 
Todian 
Ocean 
hecome 
south-west 
monsoons. 


96 THE PHYSICAL GEOGRAPHY OF THE SEA. 


of the Ghauts, Peruvian-like,’ cool, rainless, and dry ; 
wherefore that narrow strip of country between the 
Ghauts and the Arabian Sea would, lke that in Peru 
between the Andes and the Pacific, remain without rain 
for ever, were it not for other agents which are at work 
about India, and not about Peru. The work of the 
agents to which I allude is felt in the monsoons, and 
these prevail in India, and not in Peru. 

After the north-east trades have blown out their sea- 
son, which in India ends in April,* the great arid plains 
of Central Asia, of Tartary, Thibet, and Mongolia, become 
heated up; they rarefy the air of the north-east trades, 
and cause it to ascend. This rarefaction and ascent, by 
their demand for an indraught, are felt by the air which, 
the south-east trade-winds bring to the equatorial Dol- 
drums of the Indian Ocean; it rushes over into the 
northern hemisphere to supply the upward draught from 
the heated plains as the south-west monsoons, The 
forces of diurnal rotation assist®* to give these winds their 
westing. Thus the south-east trades, in certain parts 
of the Indian Ocean, are converted, during the summer 
and early autumn, into south-west monsoons, These, 
then, come from the Indian Ocean and Sea of Arabia 
loaded with moisture, and striking with it perpendicu- 
larly upon the Ghauts, precipitate upon that narrow strip 
of land between this range and the Arabian Sea an 
amount of water that is truly astonishing. Here, then, 
are not only the conditions for causing more rain, now on 
the west, now on the east side of this mountain range, 
but the conditions also for the most copious precipitation. 
Accordingly, when we come to consult rain gauges, and 


1 $199, 2 § 200, 8 § 44, 


THE ATMOSPHERE. 97 


to ask meteorological observers in India about the fall of 
rain, they tell us that on the western slopes of the Ghauts 
it sometimes reaches the enormous depth of twelve or 
fifteen inches in one day.* Were the Andes stretched 
along the eastern instead of the western coast of America, 
we should have an amount of precipitation on their east- 
ern slopes that would be truly astonishing ; for the water 
which the Amazon and the other majestic streams of 
South America return to the ocean would still be preci- 
pitated between the sea-shore and the crest of these 
mountains. 

These winds of India then continue their course to the 
Himalaya range as dry winds. In crossing this range, 
they are subjected to a lower temperature than that to 
which they were exposed in crossing the Ghauts. Here 
they drop more of their moisture in the shape of snow 
and rain, and then pass over into the thirsty lands beyond 
with scarcely enough vapour in them to make even a 
cloud. Thence they ascend into the upper air, there to 
_ become counter-currents in the general system of atmos- 
pherical circulation. 

The Regions of Greatest Precipitation.—We shall 
now be enabled to determine, if the views which I have 
been endeavouring to present be correct, what parts of 
the earth are subject to the greatest fall of rain. They 
should be on the slopes of those mountains which the 
trade-winds first strike, after having blown across the 
greatest tract of ocean. The more abrupt the elevation, 
and the shorter the distance between the mountain top 
and the ocean,’ the greater the amount of precipitation. 


* Keith Johnston. 
1 § 199. 
7 


OHAPTER 
III. 


Enormous 
depth of 
rain on the 
Ghauts. 


§ 202 


Dry winds 
on the 
Himalayas 


§ 203 


The 
regions of 
greatest 
precipita- 
tion. 


98 THE PHYSICAL GEOGRAPHY OF THE SEA. 


caapter If, therefore, we commence at the parallel of about 30° 
aa north in the Pacific, where the north-east trade-winds 
first strike that ocean, and trace them through their cir- 
cuits till they first strike high land, we ought to find 

such a place of heavy rains. 
¢204 Commencing at this parallel of 30°, therefore, in the 
Course of North Pacific, and tracing thence the course of the north- 
tate east trade-winds, we shall find that they blow thence, 
“mand reach the region of equatorial calms near the Caro- 
line Islands. Here they rise up; but, instead of pursu- 
ing the same course in the upper stratum of winds 
through the southern hemisphere, they, in consequence of 
the rotation of the earth, are made to take a south-east 
course. They keep in this upper stratum until they 
reach the calms of Capricorn, between the parallels of 
30° and 40°, after which they become the prevailing 
north-west winds of the southern hemisphere, which cor- 
respond to the south-west of the northern. Continuing 
on to the south-east, they are now the surface winds ; 
they are going from warmer to cooler latitudes; they 
Astonish- become as the wet sponge; and are abruptly intercepted 


ing fall of 


eee. by the Andes of Patagonia, whose cold summit com- 

presses them, and with its low dew-point squeezes the 

water out of them. Captain King found the astonishing 

fall of water here of nearly thirteen feet (one hundred 

and fifty-one inches) in forty-one days; and Mr. Darwin 

reports that the sea-water along this part of the South 

American coast is sometimes quite fresh, from the vast 
quantity of rain that falls. 

§205 We ought to expect a corresponding rainy region to 

be found to the north of Oregon; but there the moun- 


——y 


1 ¢ 126. as 197, 


THE ATMOSPHERE. 99 


tains are not so high, the obstruction to the south-west 
winds is not so abrupt, the highlands are farther from 
the coast, and the air which these winds carry in their 
circulation to that part of the coast, though it be as 
-heavily charged with moisture as at Patagonia, has a 
greater extent of country over which to deposit its rain, 
and consequently, the fall to the square inch will not be 
as great.* 

In like manner, we should be enabled to say in what 
part of the world the most equable climates are to be 
found. They are to be found in the equatorial calms, 
where the north-east and south-east trades meet fresh 
from the ocean, and keep the temperature uniform under 
a canopy of perpetual clouds. 

Amount of Evaporation.—The mean annual fall of 
rain on the entire surface of the earth is estimated at 
about five feet. 

To evaporate water enough annually from the ocean 
to cover the earth, on the average, five feet deep with 
rain; to transport it from one zone to another; and to 
precipitate it in the right places, at suitable times, and in 
the proportions due, is oue of the offices of the grand 
atmospherical machine. This water is evaporated princi- 
pally from the torrid zone. Supposing it all to come 
thence, we shall have, encircling the earth, a belt of 
ocean three thousand miles in breadth, from which this 
atmosphere evaporates a layer of water anually sixteen 


* IT have, through the kindness of A. Holbrook, Esq., United States Attorney 
for Oregon, received the Oregon Spectator of February 13, 1851, containing the 
Rey. G. H. Atkinson’s Meteorological Journal, kept in Oregon city during the 
month of January 1851. The quantity of rain and snow for that month is 13.63 


inches, or about one third the average quantity that falls at Washington during 
the year, 


CHAPTER 
III. 


Why 
greater 
than” 
Oregon. 


§ 206 
Most 


equable 
climates. 


§ 207 


$ 208 


Evapora- 


tion. 


100 THE PHYSICAL GEOGRAPHY OF THE SEA. 


onapter feet in depth. And to hoist up as high as the clouds, an 


III. 


aa lower down again all the water in a lake sixteen feet deep, 

machinery and three thousand miles broad, and twenty-four thou- 

; ae sand long, is the yearly business of this invisible ma- 
chinery. What a powerful engine is the atmosphere ! 
and how nicely adjusted must be all the cogs, and wheels, 
and springs, and compensations of this exquisite piece of 
machinery, that it never wears out nor breaks down, nor 
fails to do its work at the right time, and in the right 
way ! 

§209 In his annual report to the Society (Transactions of the 
La Bombay Geographical Society from May, 1849, to 
erapora- August, 1850, vol. ix.), Dr. Buist, the secretary, states, 

on the authority of Mr. Laidly, the evaporation at Cal- 
entta to be “about fifteen feet annually; that between the 
Cape and Calcutta it averages, in October and November, 
nearly three-fourths of an inch daily; between 10° and 
20° in the Bay of Bengal, it was found to exceed an inch 
daily. Supposing this to be double the average through- 
out the year, we should,” continues the doctor, “have 
eighteen feet of evaporation annually.” 

§210 If, in considering the direct observations upon the 
Evapora daily rate of evaporation in India, it be remembered that 
Indian. the seasons there are divided into wet and dry; that in 

the dry season, evaporation in the Indian Ocean, because 
of its high temperature, and also of the high temperature 
and dry state of the wind, probably goes on as rapidly as 
it does any where else in the world; if, moreover, we re- 
Estimate’ member that the regular trade-wind regions proper at 


wind su- sea are regions of small precipitation ;' that evaporation 
ace. 
is going on from them all the year round, we shall have 


THE ATMOSPHERE, 101 


reason to consider the estimate of sixteen feet annually 
for the trade-wind surface of the ocean not too high. 

We see the light beginning to break upon us, for we 
now begin to perceive why it is that the proportions be- 
tween the land and water were made as we find them in 
nature. If there had been more water and less land, we 
should have had more rain, and vice versa; and then 
climates would have been different from what they now 
are, and the inhabitants, animal or vegetable, would 
not have been as they are. And as they are, that wise 
Being who, in his kind providence, so watches over and 
regards the things of this world that he takes notice of 
the sparrow’s fall, and numbers the very hairs of our 
head, doubtless designed them to be. 

The mind is delighted, and the imagination charmed, 
by contemplating the physical arrangements of the earth 
from such points of view as this is which we now have 
before us; from it the sea, and the air, and the land, 
appear each as a part of that grand machinery upon 
which the well-being of all the inhabitants of earth, sea, 
and air depends ; and which, in the beautiful adaptations 
that we are pointing out, affords new and striking evi- 
dence that they all have their origin in ONE omniscient 
idea, just as the different parts of a watch may be consi- 
dered to have been constructed and arranged according 
to one human design. 

In some parts of the earth, the precipitation is greater 
than the evaporation; thus the amount of water borne 
down by every river that runs into the sea may be con- 
sidered as the excess of the precipitation over the evapo- 
ration that takes place in the valley drained by that river. 


OHAPTER 
Iil, 


§ 211 
Why the 
propor- 
tions of 
land and 
water are 
as we find 
them. 


§ 212 
Beauty of 
physical 
arrange- 
ments of 
the earth. 


§ 213 


Precipita- 


tion 
sometimes 
greater 
than eva- 
poration, 


CHAPTER 
III. 


§ 214 


§ 215 
In other 
parts 
exactly 
equal. 


§$ 216 


Valley of 
Caspian 
Sea. 


§ 217 


§ 218 
In others 
neither e- 
vaporation 
nor preci- 
pitation 
takes place 


§ 219 


Terrestrial] 
adapta- 
tions. 


102 THE PHYSICAL GEOGRAPHY OF THE SEA. 


This excess comes from the sea; the winds convey it 
to the interior ; and the forces of gravity, dashing it along 
in mountain torrents or gentle streams, hurry it back to 
the sea again. 

In other parts of the earth, the evaporation and preci- 
pitation are exactly equal, as in those inland basins such 
as that in which the city of Mexico, Lake Titicaca, the 
Caspian Sea, &c., are situated, which basins have no ocean 
drainage. 

If more rain fell in the valley of the Caspian Sea than 
is evaporated from it, that sea would finally get full and 
overflow the whole of that great basin. If less fell than 
is evaporated from it again, then that sea, in the course 
of time, would dry up, and plants and animals there 


- would all perish for the want of water. 


In the sheets of water which we find distributed over 
that and every other inhabitable inland basin, we see 
reservoirs, or evaporating surfaces, just sufficient for the 
supply of that degree of moisture which is best adapted 
to the well-being of the plants and animals that people 
such basins. 

In other parts of the earth still, we find places, as the 
Desert of Sahara, in which neither evaporation nor pre- 
cipitation takes place, and in which we find neither plant 
nor animal. 

ADAPTATIONS.—In contemplating the system of terres- 
trial adaptations, these researches teach one to regard the 
mountain ranges and the great deserts of the earth as the 
astronomer does the counterpoises to his telescope—though 
they be mere dead weights, they are, nevertheless, neces- 
sary to make the balance complete, the adjustments of 


THE ATMOSPHERE. 1038 


his machine perfect. These counterpoises give ease to onaprex 
the motions, stability to the performance, and accuracy se! 
to the workings of the instrument. They are “ compen- 
sations.” 

Whenever I turn to contemplate the works of nature, g 999 
T am struck with the admirable system of compensation, System of 
with the beauty and nicety with which every department "hie en 
is poised by the others; things and principles are meted 
out in directions apparently the most opposite, but in 
proportions so exactly balanced and nicely adjusted that 
results the most harmonious are produced. 

It is by the action of opposite and compensating forces § 221 
that the earth is kept in its orbit, and the stars are held By it the 


earth is 


suspended in the azure vault of heaven; and these forces pan its 
are so exquisitely adjusted, that, at the end of a thousand 
years, the earth, the sun, and moon, and every star in 
the firmament, is found to come and stand in its proper 
place at the proper moment. 
Nay, philosophy teaches us that when the little snow- § 992 


drop, which in our garden-walks we see raising its beau- whee 
tiful head at “the singing of birds,” to remind us that teaches by 
“the winter is passed and gone,” was created, the whole aoe 
mass of the earth, from pole to pole, and from circum- 
ference to centre, must have been taken into account and 
weighed, in order that the proper degree of strength 

might be given to its tiny fibres. 

Botanists tell us that the constitution of this plant is § 223 

such as to require that, at a certain stage of its growth, 

the stalk shouid bend, and the flower should bow its 

head, that an operation may take place which is necessary 


in order that the herb should produce seed after its kind ; 


CHAPTER 
III. 


Its consti- 
tution. 


$ 224 


Perfect 


adaptation 


§ 225 


Effects of 
east wind. 


104 THE PHYSICAL GEOGRAPHY OF THE SEA. 


and that, after this fecundation, its vegetable health re- 
quires that it should lift its head again and stand erect. 
Now, if the mass of the earth had been greater or less, 
the force of gravity would have been different; in that 
case, the strength of fibre in the snow-drop, as it is, would 
have been too much or too little; the plant could not 
bow or raise its head at the right time, fecundation could 
not take place, and its family would have become extinct 
with the first individual that was planted, because its 
“seed” would not have been “in itself,” and therefore it 
could not have reproduced itself, and its creation would 
have been a failure. 

Now, if we see such perfect adaptation, such exquisite 
adjustment, in the case of one of the smallest flowers of 
the field, how much more may we not expect “compen- 
sation” in the atmosphere and the ocean, upon the right 
adjustment and due performance of which depends not 
only the life of that plant, but the well-being of every in- 
dividual that is found in the entire vegetable and animal 
kingdoms of the world ? 

When the east winds blow along the Atlantic coast for 
a little while, they bring us air saturated with moisture 
from the Gulf Stream, and we complain of the sultry, op- 
pressive, heavy atmosphere ; the invalid grows worse, and 
the well man feels ill, because, when he takes this atmo- 
sphere into his lungs, it is already so charged with mois- 
ture that it cannot take up and carry off that which 
encumbers his lungs, and which nature has caused his 
blood to bring and leave there, that respiration may take 
up and carry off. At other times the air is dry and hot; 
he feels that it is conveying off matter from the lungs 


THE ATMOSPHERE. 105 


too fast; he realizes the idea that it is consuming him, 
and he calls the sensation burning. 

Therefore, in considering the general laws which govern 
the physical agents of the universe, and regulate them in 
the due performance of their offices, I have felt myself 
constrained to set out with the assumption that, if the 
atmosphere had had a greater or less capacity for mois- 
ture, or if the proportion of land and water had been 
different—if the earth, air, and water had not been in 
exact counterpoise—the whole arrangement of the animal 
and vegetable kingdoms would have varied from their 
present state. But God, for reasons which man may 
never know, chose to make those kingdoms what they 
are ; for this purpose it was necessary, in his judgment, 
to establish the proportions between the land and water 
and the desert just as they are, and to make the capacity 
of the air to circulate heat and moisture just what it is, 
and to have it to do all its work in obedience to law and 
in subservience to order. If it were not so, why was 
power given to the winds to lift up and transport mois- 
ture, and to feed the plants with nourishment? or why 
was the property given to the sea by which its waters 
may become first vapour, and then fruitful showers or 
gentle dews? If the proportions and properties of land, 
sea, and air were not adjusted according to the reciprocal 
capacities of all to perform the functions required by each, 
why should we be told that Hr “measured the waters in 
the hollow of his hand, and comprehended the dust in a 
measure, and weighed the mountains in scales, and the 
hills in a balance?” Why did he span the heavens, but 
that he might mete out the atmosphere in exact propor- 


CHAPTER 
Ill. 


§ 226 


Assump- 
tion. 


106 THE PHYSICAL GEOGRAPHY OF THE SEA. 


cuarrer tion to all the rest, and impart to it those properties and 


§ 227 


Lessons 
taught by 
sea and 
air. 


powers which it was necessary for it to have, in order 
that it might perform all those offices and duties for 
which he designed it ? 

Harmonious in their action, the air and sea are obe- 
dient to law and subject to order in all their movements ; 
when we consult them in the performance of their mani- 
fold and marvellous offices, they teach us lessons concern- 
ing the wonders of the deep, the mysteries of the sky, 
the greatness, and the wisdom, and goodness of the Crea- 
tor, which make us wiser and better men. The investi- 
gations into the broad-spreading circle of phenomena 
connected with the winds of heaven and the waves of 
the sea are second to none for the good which they do 
and the lessons which they teach. The astronomer is 
said to see the hand of God in the sky ; but does not the 
right-minded mariner, who looks aloft as he ponders over 
these things, hear his voice in every wave of the sea that 
“claps its hands,” and feel his presence in every breeze 
that blows ? 


LAND AND SEA BREEZES. 107 


CHAPTER IV. 


LAND AND SEA BREEZES. 


Lieutenant Jansen, § 228.—His Contributions, 229.—The Sea-breeze, 230.—An 
Illustration, 231.—The Land-breeze, 232.—Jansen’s Account of the Land and 
Sea Breeze in the East Indies, 234.—A Morning Scene, 235.—The Calm, 237. 
The Inhabitants of the Sea going to Work, 289.— Noon, 240.—The Sea-breeze 
dies, 245.—The Land-breeze, 247.—A Discussion, 248.—Why Land and Sea 
Breezes are not of equal Freshness on the Sea-shore of all Countries, 252.— 
The Sea-breeze at Valparaiso, 255.—The Night, 258.—A Contrast, 263. 


I] HAVE been assisted in my investigations into these cuarrea 


phenomena of the sea by many thinking minds; among 
those whose debtor I am, stands first and foremost the 
clear head and warm heart of a foreign officer, Lieutenant Lienten- 
Marin Jansen, of the Dutch navy, whom I am proud ie 
to call my friend. He is an ornament to his profession ; 

and a more accomplished officer it has never been my 

good fortune to meet in any service. He has entered 

this magnificent field of research con amore, and has 
proved to be a most zealous and efficient fellow-labourer. 
Promotion in the Dutch navy unfortunately goes by 
seniority ; if it went by merit, I should I am sure, have 

the pleasure of writing of him as admiral. 

Jansen has served many years in the East Indies. He g 229 
observed minutely and well. He has enriched my humble His conti. 
contributions to the “Physical Geography of the Sea” pre 
with contributions from the storehouse of his knowledge, 
set off and presented in many fine pictures, and has 
appended them to a translation of the first edition of 
this work into the Dutch language. He has added a 
chapter on the land and sea breezes; another on the 


CHAPTER 


Lic 


§ 230 


The sea- 
breeze. 


§ 231 


Tllustra- 
tion. 


108 THE PHYSICAL GEOGRAPHY OF.THE SEA, 


changing of the monsoons in the East Indian Archi- 
pelago: he has also extended his remarks to the north- 
west monsoon, to hurricanes, the south-east trades of the 
South Atlantic, and to winds and currents generally, 


In many parts of the world the oppressive heat of 
summer is modified, and the climate of the sea-shore is 


made refreshing and healthful, by the alternation of winds 
which come from the sea by day and from the land by night. 
About ten in the morning the heat of the sun has played 
upon the land with sufficient intensity to raise its tem- 
perature above that of the water. A portion of this heat, 
being imparted to the superincumbent air, causes it to 
rise, when the air, first from the beach, then from the 
sea, to the distance of several miles, begins to flow in 
with a most delightful and invigorating freshness. 

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 the 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; and 
thus we have 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 nine or ten o’clock it and the air above it are 
cooled below the sea temperature. The atmosphere on 
the land thus becomes heavier than that on the sea, and, 
consequently, there is a wind seaward which we call the 
land-breeze. 


LAND AND SEA BREEZES. 109 


Jansen thus describes this phenomenon in the East curren 
DY 


Indies, where one must live fully to appreciate its benign 
influences. ee 
JANSEN’S AccountT.*—“ A long residence in the East § 234 
Indian Archipelago, and, consequently, in that part of the cue 
world where the investigations of the Observatory at tions 
Washington have not extended, has given me the oppor- 
tunity of studying the phenomena which there occur in 
the atmosphere, and to these phenomena my attention 
was, in the first place, directed. I was involuntarily led 
from one research to another, and it is the result of these 
investigations to which I would modestly give a place at 
the conclusion of Maury’s ‘ Physical Geography of the Sea,’ 
with the hope that these first-fruits of the log-books of 
the Netherlands may be speedily followed by more and 
better. 
“ Upon the northern coast of Java, the phenomenon of § 235 
daily land and sea breezes is finely developed. There, as Land 


and sea 


the gorgeous ‘ eye of day’ rises almost perpendicularly biseist ca 
from the sea with fiery ardour, in a cloudless sky, it is ern coast 
greeted by the volcanoes with a column of white smoke, mee 
which, ascending from the conical summits high in the 
firmament above, forms a crown, or assumes the shape 

of an immense bouquet,} that they seem to offer to the 

dawn; then the joyful land-breeze plays over the flood, Lana- 
which, in the torrid zone, furnishes, with its fresh breath, Bene 


so much enjoyment to the inhabitants of that. sultry belt 


* Jansen’s Appendix to the ‘‘ Physical Geography of the Sea,” translated from 
the Dutch by Mrs. Dr. Breed, Washington. 

+ Upon the coast of Java I saw daily, during the east monsoon, such a column 
of smoke ascending at sunrise from Bromo, Lamongan, and Smiro. Probably 
there is then no wind above.—J ANsEN. 


CHAPTER 
TVs 


It effects. 


§ 236 


§ 237 
It dies 
away. 


§ 238 


110 THE PHYSICAL GEOGRAPHY OF THE SEA, 


of earth, for, by meaps of it, everything is refreshed and 
beautified. Then, under the influence of the glorious 
accompaniments of the break of day, the silence of the 
night is awakened, and we hear commencing everywhere 
the morning hymn of mute nature, whose gesticulation is 
so expressive and sublime. All that lives feels the neces- 
sity of pouring forth, each in its way, and in various 
tones and accents, from the depths of inspiration, a song 
of praise. 

“The air, still filled with the freshness of the evening 
dew, bears aloft the enraptured song, as, mingled with 
the jubilee tones which the contemplation of nature 
everywhere forces from the soul, it gushes forth in deep 
earnestness to convey the daily thank-offering over the 
sea, over hill and dale.* 

“As the sun ascends the sky, the azure vault is bathed 
in dazzling light; now the land-breeze, wearied with play, 
goes to rest. Here and there it still plays over the 
water, as if it could not sleep; but finally becoming 
exhausted, it sinks to repose in the stillness of the calm. 
But not so with the atmosphere: it sparkles, and glitters, 
and twinkles, becoming clear under the increasing heat, 
while the gentle swelling of the now polished waves, 
reflects, like a thousand mirrors, the rays of lght which 
dance and leap to the tremulous but vertical movements 
of the atmosphere. 

“Like pleasant visions of the night, that pass before 
the mind in sleep, so do sweet phantoms hover about the 
land-breeze as it slumbers upon the sea. The shore seems 


* In the very fine mist of the morning, a noise—for example, the firing of 
cannon—at a short distance is scarcely heard, while at mid-day, with the sea- 
breeze, it penetrates for miles with great distinctness. —J ANSEN. 


LAND AND SEA BREEZES. (ea 


to approach and to display all its charms to the mariner omaprss 
in the offing. All objects become distinct and more ae 


: ; . ¢ Descrip- 
clearly delineated,* while, upon the sea, small fishing- tion. 


boats loom up like large vessels. The seaman, drifting 
along the coast, and misled by the increasing clearness 
and mirage, believes that he has been driven by a current 
toward the land; he casts the lead, and looks anxiously 
out for the sea-breeze, in order to escape from what he 
believes to be threatening danger.; The planks burn 
under his feet; in vain he spreads the awning to shelter 
himself from the broiling sun. Its rays are oppressive; 
repose does not refresh; motion is not agreeable. 

“The inhabitants of the deep, awakened by the clear § 239 
light of day, prepare themselves for labour. Corals, and 
thousands of crustacea, await, perhaps impatiently, the 
coming of the sea-breeze, which shall cause evaporation 
to take place more rapidly, and thus provide them with a 
bountiful store of building material for their picturesque 
and artfully constructed dwellings: these they know how 
to paint and to polish in the depths of the sea more 
beautifully than can be accomplished by any human art. 
Like them, also, the plants of the sea are dependent upon 
the winds, upon the clouds, and upon the sunshine; for 
upon these depend the vapour and the rains which feed 
the streams that bring nourishment. for them into the sea. 


* The transparency of the atmosphere is so great that we can sometimes dis- 
cover Venus in the sky in the middle of the day.—J aNsEN. 

+ Especially in the rainy season the land looms very greatly; then we see 
mountains which are from 5000 to 6000 feet high at a distance of 80 or 100 Eng- 
lish miles, 

t The archipelago of coral islands on the north side of the Straits of Sunda is 
remarkable. Before the salt water flowed from the Straits, it was deprived of 
the solid matter of which the Thousand Islands are constructed. A similar 
group of islands is found between the Straits of Macassar and Balie.—JAvsEn. 


112 THE PHYSICAL GEOGRAPHY OF THE SEA, 


cuarter “ When the sun reaches the zenith, and his stern eye, 
ae with burning glare, is turned more and more upon the 
§ 240 

Descrip- 


tion con” even as the magnetizer exercises his will upon his subject, 


Java Sea, the air seems to fall into a magnetic sleep; yet, 


and the latter, with uncertain and changeable gestures, 
gradually puts himself in motion, and, sleeping, obeys that 
will, so also we see the slow efforts of the sea-breeze to 
repress the vertical movements of the air, and to obey the 
will which calls it to the land. This vertical movement 
appears to be not easily overcome by the horizontal, 
which we call wind. Yonder, far out upon the sea, arises 
and disappears alternately a darker tint upon the other- 
wise shining sea-carpet; finally, that tint remains and 
approaches; that is the long-wished-for sea-breeze; and 
yet it is sometimes one, yes, even two hours, before that 
darker tint is permanent, before the sea-breeze has regu- 
larly set in. : 

§ 241 “Now small white clouds begin to rise above the hori- 
zon; to the experienced seaman they are a prelude to a 
fresh sea-breeze. We welcome the first breath from 
the sea; it is cooling, but it soon ceases; presently it is 
succeeded by other grateful puffs of air, which continue 
longer; presently they settle down into the regular sea- 
breeze, with its cooling and refreshing breath. 

§ 242 “The sun declines, and the sea-wind—that is, the 

Sea-wind. common trade-wind or monsoon which is drawn toward 

the land—is awakened. It blows right earnestly, as if 
it would perform its daily task with the greatest possibie 
ado. 

§ 243 “The air, itself refreshed upon the deep, becomes gray 
from the vapour which envelopes the promontories in 


LAND AND SEA BREEZES, Males 


mist, and curtains the inland with dark clouds. The 
land, relieved by the darker tint which it gives to the 
mist, looms up beautifully; the distance cannot be esti- 
mated. The sailor thinks himself farther from shore than 
he really is, and steers on his course carelessly, while the 
capricious wind lashes the waters, and makes a short and 
broken sea, from the white caps of which light curls are 
torn, with sportive hand, to float away like party-coloured 
streamers in the sunbeam. In the meanwhile clouds 
appear now and then high in air, yet it is too misty to 
see far. 

“The sun approaches the horizon, Far over the land 
the clouds continue to heap up; already the thunder is 
heard among the distant hills; the thunder-bolts rever- 
berate from hill-side to hill-side, while through the mist 
the sheets of lightning are seen.* 

“Finally, the ‘king of day’ sinks to rest; now the 
mist gradually disappears, and as soon as the wind has 
laid down the lash, the sea, which, chafing and fretting, 
had with curled mane resisted its violence, begins to go 
down also. Presently both winds and waves are hushed, 
and all is again still. Above the sea, the air is clearer 
or slightly clouded; above the land, it is thick, dark, 
and swollen. To the feelings, this stillness is pleasant. 
The sea-breeze, the driving brine that has made a salt- 
pan of the face, the short, restless sea, the dampness—all 
have grown wearisome, and welcome is the calm. There 
is, however, a somewhat of dimness in the air, an uncer- 
tain but threatening appearance. Presently, from the 


* At Buitenzorg, near Batavia, 40 English miles from the shore, 500 feet 
above the sea, with high hills around, these thunder-storms occur between 4 p.u. 
and 8 P.M. 


8 


CHAPTER 
Iv. 


Descrip- 
tion con- 
tinued. 


OFAPTER 
vs 


§ 246 


§ 247 


Land- 

breeze in 
dava not 
to be de- 


pended on. 


114 THE PHYSICAL GEOGRAPHY OF THE SEA. 


dark mass of clouds, which hastens the change of day 
into night, the thunder-storm peals forth. The rain falls 
in torrents in the mountains, and the clouds gradually 
overspread the whole sky. But for the wind, which 
again springs up, it would be alarming to the sailor, who 
is helpless in a calm. What change will take place in 
the air? The experienced seaman, who has to work 
against the trade-wind or against the monsoon, is off the 
coast, in order to take advantage of the land-breeze (the 
destroyer of the trade) so soon as it shall come. He 
rejoices when the air is released from the land, and the 
breeze comes, at first feebly, but afterward growing 
stronger, as usual, during the whole night. If the land- 
breeze meets with a squall, then it is brief, and becomes 
feeble and uncertain. We sometimes find then the per- 
manent sea-breeze close to the coast, which otherwise 
remains twenty or more English miles from it. 

“One is not always certain to get the land-breeze at 
the fixed time. It sometimes suffers itself to be waited 
for ; sometimes it tarries the whole night long. 

“During the greatest part of the rainy season, the 
land-breeze in the Java Sea cannot be depended upon. 
This is readily explained according to the theory which 
ascribes the origin of the sea and land breezes to the 
heating of the soil by day, and the cooling by means of 
radiation by night; for, during the rainy season, the 
clouds extend over land and sea, interrupting the sun's 
rays by day, and the radiation of heat by night, thus 
preventing the variations of temperature ; and from these 
variations, according to this theory, the land and sea 
breezes arise. Yet there are other tropical regions where 


LAND AND SEA BREEZES. Ths 


the land and sea breezes, even in the rainy season, regu- 
larly succeed each other. 

“The warming and the radiation alone are therefore 
not sufficient to explain all the phenomena of land and 
sea breezes, and other causes—electricity, rain, &c., appear 
to have an influence upon the regularity of the land 
winds, * 

“Upon the coast of Africa, the land-breeze is univer- 
sally scorching hot, but the sea-breeze is cool and refresh- 
ing. When this is the case, the land-breeze certainly 
cannot be occasioned by the cooling of the earth by 
radiation. When we shall have brought together all the 
observations upon the various phenomena which the land 
and sea breezes afford, then we shall be able to begin to 
found upon facts a theory which shall explain the varied 
phenomena. Thus, among other things, upon the west 
coast of Africa, from 0° 27’ 8. to 15° 24'S, according 
to Thomas Miller,+ from June to October, and, above all, 
in July, there are heavy dews, and when the dews are 
very heavy, then the land and sea breezes are invariably 
feeble—sometimes very faint.” 

[Lieutenant Jansen’s remarks are both instructive and 
suggestive. It is true that a given difference of tem- 


* My observations lead me to suspect that the position of the moon is also 
herein concerned. In the eastern outlet of Sourabaya, during the east monsoon, 
there is at full moon little land-breeze, and at new moon little sea-breeze. I 
afterward made the same observation in the Gulf of Darien. Feb. 4, 1852.—At 
the Road of Carthagena (New Grenada), full moon, sea-breeze north, under 
reefed top-sail, fresh gale; at 11 p.m., feeble and easterly. Feb. 5.—11 a.m., 
sea-breeze grows faint. 1 p.m., stronger, and between 5 and 6 p.m. fresh gale; 
double-reefed top-sail. Hach day somewhat later and less hard. Thermometer 
varying between 79° and 80°, Barometer varying between 763° and 759°, Upon 
leaving Chagres, with new moon, it was by day mostly feeble.-—J ANSEN. 

+ Nautical Magazine for June 1855.—J anseEn. 


CHAPTER 
Lie 


—— 


§ 248 


§ 249 


Land- 

breeze on 
the coast 
of Africa. 


Observa- 
tions by 
Thomas 

Miller. 


§ 250 


CHAPTER 
IV. 


§ 251 
Philoso- 
phical rea- 
son why 
causes of 
land and 
sea- 
breezes at 
one place 
will not 
produce 
them at 
another. 


$ 252 


Scorching 
land- 
breeze on 
west coast 
of Africa. 


§ 253 


Sea-breeze 
prevails on 
the coast of 
Brazil. 


116 THE PHYSICAL GEOGRAPHY OF THE SEA, 


perature between land and water, though it may be suf 
ficient to produce the phenomena of land and sea breezes 
at one place, will not be adequate to the same effect at 
another; and the reason is perfectly philosophical. 

It is easier to obstruct and turn back the current in a 
sluggish than in a rapid stream. So, also, in turning a 
current of air first upon the land, then upon the sea— 
very slight alterations of temperature would suffice for 
this on the coast of Africa, in and about the equatorial 
calms, for instance; there the air is in a state of rest, 
and will obey the slightest call in any direction—not so 
in regions where the trades blow over the land, and are 
strong. It requires, under such circumstances, a con- 
siderable degree of rarefaction to check them, and produce 
a calm, and a still farther rarefaction to turn them back, 
and convert them into a regular sea-breeze. 

Hence the scorching land-breeze on the west coast of 
Africa: the heat there may not have been intense enough 
to produce the degree of rarefaction required to check 
and turn back the south-east trades. In that part of the 
world, their natural course is from the land to the sea, 
and therefore, if this view be correct, the sea-breeze 
should be more feeble than the land-breeze, neither should 
it last so long. 

But on the opposite side—on the coast of Brazil, as at 
Pernambuco, for instance—where the trade-wind comes 
from the sea, we should have this condition of things 
reversed, and the sea-breeze will prevail for most of the 


time—then it is the land-breeze which is feeble and of 


short duration: it is rarely felt. 
Again, the land and sea breezes in Cuba, and along 


LAND AND SEA BREEZES. ihaby/ 


the Gulf shores of the United States, will he more regular 
in their alternations than they are along the shores of 
Brazil or South Africa, and for the simple reason that 
the shore-wind named in North American waters lies 
nearly parallel with the course of the winds in their pre- 
vailing direction. In Rio de Janeiro, the sea-breeze is 
the regular trade-wind, made fresher by the daily action 
of the sun on the land. It is worthy of remark, also, 
that, for the reason stated by Jansen, the land and sea 
breezes in the winter time are almost unknown in coun- 
tries of severe cold, though, in the summer, the alterna- 
tion of wind from land to sea, and sea to land, may be 
well marked. 

ein Valparaiso, the phenomenon of the sea-breeze is 
finely developed. Valparaiso is situated near the south- 
ern border of the calm belt of Capricorn, when it is at 
its farthest southern reach, which happens in our late 
winter and early spring—the Southern summer and 
autumn. This is the dry season, when the sky is singu- 
larly clear and bright. The atmosphere, being nearly in 
a state of equilibrium, is then ready to obey even the 
most feeble impulse, and to hasten toward the place of 
any, the slightest rarefaction. 

At about ten in the morning, at this season of the 
year, the land begins to feel the sun, and there is a move- 
ment in the air. By 3 or 4 P.M, the sea-breeze comes 
rushing in from the southward and westward, and 
strikes the shipping in the harbour with the force of a 
gale. Vessels sometimes drag before it, and communica- 
tion with the shore is suspended. By 6 P.M, however, 
the wind has spent its fury, and there is a perfect calm. ] 


CHAPTER 
IV. 


Cuba. 


Rio de 
Janeiro. 


§ 255 


Phenome- 
non of sea- 
breeze 
finely de- 
veloped in 
Valparaiso 


§ 256 


Begins at 
3 or 4 p.m 


CHAPTER 
TiVic 
S200 
Quotation 
from 
Jansen. 


§ 258 


Descrip- 
tion by 
Jansen 
of land 
and sea 
breezes in 
the Java 
Sea. 


118 THE PHYSICAL GEOGRAPHY OF THE SEA. 


“ Happy he,” continues Jansen, “ who, in the Java Sea 


at evening, seeking the land-breeze off the coast, finds 


it there, after the salt-bearing, roaring sea-wind, and 
can, in the magnificent nights of the tropics, breathe 
the refreshing land-breeze, ofttimes laden with delicious 
odours.* 

“The veil of clouds, either after a squall, with or 
without rain, or after the coming of the land-breeze, is 
speedily withdrawn, and leaves the sky clearer during 
the night, only now and then flecked with dark clouds 
floating over from the land. Without these floating 
clouds the land-breeze is feeble. When the clouds float 
away from the sea, the land-breeze does not go far out 
from the coast, or is wholly replaced by the sea-breeze, 
or, rather, by the trade-wind. If the land-breeze con- 
tinues, then the stars loom forth, as if to free themselves 
from the dark vault of the heavens, but their light does 
not wholly vanquish its deep blue, though the dark fleck- 
ing of clouds comes out more distinctly near the Southern 
Cross, which smiles consolingly upon us, while Scorpio, 
the emblem of the tropical climate, stands ike a warning 
in the heavens. The starlight, which is reflected by the 
mirrored waters, causes the nights to vie in clearness 
with the early twilight in high latitudes. Numerous 
shooting stars weary the eye, although they break the 
monotony of the sparkling firmament. Their unceasing 
motion in the unfathomable ocean affords a great contrast 
to the seeming quiet of the gently-flowing aerial current 
of the land-breeze. But at times, when, 30° or 40° above 
the horizon, a fire-ball arises, which suddenly illumines 


* In the roads of Batavia, however, they are not very agreeable. —J ANSEN. 


LAND AND SEA BREEZES. 119 


the whole horizon, appearing to the eye the size of the 
fist, and fading away as suddenly as it appeared, falling 
into fiery nodules, then we perceive that, in the apparent 
calm of nature, various forces are constantly active, 
in order to cause, even in the invisible air, such com- 
binations and combustions, the appearance of which 
amazes the crews of ships. 

“When the slender keel glides quickly over the mir- 
rored waters upon the wings of the wind, it cuts for itself 
a sparkling way, and disturbs in their sleep the monsters 
of the deep, which whirl and dart quicker than an eight- 
knot ship; sweeping and turning around their disturber, 
they suddenly clothe the dark surface of the water in 
briluaney. Again, when we go beyond the limits of the 
land-breeze, and come into the continuous trade-wind, we 
occasionally see from the low-moving, round black clouds 
(unless it thunders), light blue sparks collected upon the 
extreme points of the iron belaying-pins, &c. ;* then the 
crew appear to fear a new danger, against which courage 
is unavailing, and which the mind can find no power to 
endure. The fervent, fiery nature inspires the traveller 
with deep awe. They who, under the beating of the 
storm and terrible violence of the ocean, look danger 
courageously in the face, feel, in the presence of these 
phenoma, insignificant, feeble, anxious. Then they per- 
ceive the mighty power of the Creator over the works of 
his creation. 

“ And how can the uncertain, the undetermined sensa- 
tions arise which are produced by the clear yet sad light 


* T have seen this in a remarkable degree upon the south coast of Java; these 
sparks were then seen six feet above the deck, upon the frames of timber, (hous- 
sen der blokken), in the implements, &¢.—JANSEN. 


CHAPTER 
Iv. 


§ 259 


Phospho- 
ric light. 


Electricity 


§ 260 


120 THE PHYSICAL GHOGRAPHY OF THE SEA. 


cuapten Of the moon?—she who has always great tears in her 
pera eyes, while the stars look sweetly at her, as if they loved 
to trust her and to share her affliction ?* 

§261 “In the latter part of the night, the land-breeze*sinks 
Fickleness to sleep, for it seldom continues to blow with strength, 
breeze but is always fickle and capricious. With the break of 

day it again awakes, to sport a while, and then gradually 
dies away as the sun rises, The time at which it becomes 
calm after the land and sea breezes is indefinite, and the 
calms are of unequal duration. 

s2¢2  “ Generally, those which precede the sea-breeze are 
Camsthat rather longer than those which precede the land-breeze. 
ana 'The temperature of the land, the direction of the coast- 
breezes line with respect to the prevailing direction of the trade- 

wind in which the land is situated, the clearness of the 
atmosphere, the position of the sun, perhaps also that of 
the moon, the surface over which the sea-breeze blows, 
possibly also the degree of moisture and the electrical 
state of the air, the heights of the mountains, their extent, 
and their distance from the coast, all have influence 
thereon. Local observations in regard to these can afford 
Limit. much light, as well as determine the distance at which 
the land-breeze blows from the coast, and beyond which 
the regular trade-wind or monsoon continues uninter- 
ruptedly to blow. The direction of land and sea winds 
must also be determined by local observations, for the 
idea is incorrect that they should always blow perpendi- 


cular to the coast-line. 


* Some one has ventured the remark, that at full moon, near the equator, more 
and darker dew falls than at new moon, and to this are ascribed the moonheads 
(maan hoofden), which I have seen, however, but once during all the years which 
I have spent between-tlie tropics. —JANSEN. 


LAND AND SEA BREEZES. IPA 


“Scarcely has one left the Java Sea,—which is, as it 
were, an inland sea between Sumatra, Borneo, J ava, and 
the archipelago of small islands between both of the last- 
naméd,—than, in the blue waters of the easterly part of 
the East Indian archipelago, nature assumes a_ bolder 
aspect, more in harmony with the great depth of the 
ocean. The beauty of the Java Sea, and the delightful 
phenomena which air and ocean display, have here ceased. 
The scene becomes more earnest. The coasts of the 
eastern islands rise boldly out of the water, far in whose 
depths they have planted their feet. The south-east 
wind, which blows upon the southern coasts of the chain 
of islands, is sometimes violent, always strong through 
the straits which separate them from each other, and this 
appears to be more and more the case as we go eastward. 
Here, also, upon the northern coast, we find land-breezes, 
yet the trade-wind often blows so violently that they have 
not sufficient power to force it beyond the coast. 

“ Owing to the obstruction which the chain of islands 
presents to the south-east trade-wind, it happens that it 
blows with violence away over the mountains, apparently 
as the land breeze does upon the north coast ;* yet this 
wind, which only rises when it blows hard from the 
south-east upon the south coast, is easily distinguished 
from the gentle land-breeze. 

“The regularity of the land and sea breezes in the Java 
Sea and upon the coasts of the northern range of islands, 
Banea, Borneo, Celebes, &e, during the east monsoon, 
must in part be ascribed to the hindrances which the 


* Such is the case, among others, in the Strait Madura, upon the heights of 
Bezoekie. 


CHAPTER 


§ 263 
Easterly 
part of 
Kast 
Indian 
archipel- 


ar 
ago. 


§ 264 


Effects of 
the ob- 
struction 
of islands 


§ 265 


Cause of 
regularity 
of Jand 
and sea 
breezes in 
Java Sea. 


CHAPTER 
IV. 


R22 THE PHYSICAL GEOGRAPHY OF THE SEA. 


south-east trade-wind meets in the islands which lie 
directly in its way; in part to the inclination toward 
the east monsoon which the trade-wind undergoes after 
it has come within the archipelago; and, finally, to its 
abatement as it approaches the equator. The causes 
which produce the land-breezes thus appear collectively 
not sufficiently powerful to be able to turn back a strong 
trade-wind in the ocean.” 


RED FOGS AND SEA DUST. 1238 


CHAPTER V. 


RED FOGS AND SEA DUST. 


Where found, § 266.—Tallies on the Wind, 272.—Where taken up, 278.—Hum- 
boldt’s Description, 282.—Questions to be answered, 284.—What Effects the 
Deserts have upon the General Circulation of the Air, 286.—Information 
derived from Sea Dust, 288.—Limits of Trade-winds, 289.—Breadth of Calm 
Belts, 290. 


SEAMEN tell us of “red fogs” which they sometimes cnarrer 
Vv. 

encounter, especially in the vicinity of the Cape de Verd —— 

Islands. In other parts of the sea, also, they meet nee 


Red fogs 
showers of dust. What these showers precipitate in the *{** 


dust. 
Mediterranean is called “sirocco dust,” and in other 
parts “ African dust,” because the winds which accom- 
pany them are supposed to come from the Sirocco desert, 
or some other parched land of the continent of Africa. 
It is of a brick-red or cinnamon colour, and it sometimes 
comes down in such quantities as to cover the sails and 
rigging, though the vessel may be hundreds of miles from 
the land. 

Now, the patient reader who has had the heart to g 267 

follow me, in the preceding chapter, around with “ the Proof 


wanted 


wind in his circuits,” will perceive that proof is yet tnat te 
wanting to establish it as a fact, that the north-east and zee 
south-east trades, after meeting and rising up in the gyoiane 
equatorial calms, do cross over and take the paths repre- bese 
sented by C and G, Plate I. eee 
Statements and reasons and arguments enough have § 268 
already been made and adduced to make it highly pro- 


bable, according to human reasoning, that such is the 


CHAPTER 


§ 269 
Difficulty 
of finding 
such proof. 


§ 270 


§ 271 
Eliren- 
berg’s dis- 
covery. 


§ 272 


124 THE PHYSICAL GEOGRAPHY OF THE SEA. 


ease ; and though the theoretical deductions, showing such 
to be the case, be never so plausible, positive proof that 
they are true cannot fail to be received with delight and 
satisfaction. 

Were it possible to take a portion of this air, repre- 
senting, as it travels along with the south-east trades, the 
general course of atmospherical circulation, and to put a 
tally on it by which we could follow it in its circuits and 
always recognise it, then we might hope actually to 
prove, by evidence the most positive, the channels through 
which the air of the trade-winds, after ascending at the 
equator, returns whence it came. 

But the air is invisible ; and it is not easily perceived 
how either marks or tallies may be put upon it, that it 
may be traced in its paths through the clouds. The 
sceptic, therefore, who finds it hard to believe that the 
general circulation is such as Plate I. represents it to be, 
might consider himself safe in his unbelief were he to 
declare his willingness to give it up the moment any one 
should put tallies on the wings of the wind, which would 
enable him to recognise that air again, and those tallies, 
when found at other parts of the earth’s surface. 

As difficult as this seems to be, it has actually been 
done. Ehrenberg, with his microscope, has established, 
almost beyond a doubt, that the air which the south-east 
trade-winds bring to the equator does rise up there and 
pass over into the northern hemisphere. 

The Sirocco, or African dust, which he has been ob- 


Tallies put gerving so closely, has turned out to be tallies put upon 


on the 
wind. 


the wind in the other hemisphere; and this beautiful 
instrument of his enables us to detect the marks on these 


RED FOGS AND SEA DUST. 25 


little tallies as plainly as though those marks had been cnaprer 
written upon labels of wood and tied to the wings of the wea 
wind, 

This dust, when subjected to microscopic examination, § 273 
is found to consist of infusoria and organisms whose ha- ahead 
bitat is not Africa, but South America, and in the south- neem 
east trade-wind region of South America. Professor 
Ehrenberg has examined specimens of sea dust from the 
Cape de Verds and the regions thereabout, from Malta, 
Genoa, Lyons, and the Tyrol; and he has found a simi- 
larity among them as striking as it would have been had 
these specimens been all taken from the same pile. South Resutts. 
American forms he recognises in all of them; indeed 
they are the prevailing forms in every specimen he has 
examined. 

It may, I think, be now regarded as an established g 274 
fact, that there is a perpetual upper current of air from DESH ear 
South America to North Africa; and that the volume of tromsoutn 
air which flows to the northward in these upper currents is ames 
nearly equal to the volume which flows to the southward 
with the north-east trade-winds, there can be no doubt. 

The “rain dust” has been observed most frequently s 275 
to fall in spring and autumn ; that is, the fall has occurred rain aust 
after the equinoxes, but at intervals from them varying para 
from thirty to sixty days, more or less. To account for aan eo 
this sort of periodical occurrence of the falls of this dust, “““”” 
Ehrenberg thinks it “necessary to suppose @ dust-clowd rnren- 
to be held constantly swimming in the atmosphere by nies 
continuous currents of air, and lying in the region of 
the trade-winds, but suffering partial and periodical 
deviations.” 


126 THE PHYSICAL GEOGRAPHY OF THE SEA. 


cuapteR It has already been shown} that the rain or calm belt 

between the trades travels up and down the earth from 

> 276 north to south, making the rainy season wherever it goes. 
The reason of this will be explained in another place. 

977 ‘This dust is probably taken up in the dry and not in 

This dust the wet season. Instead, therefore, of its being “ held 


probably 


takenup in clouds suffering partial and periodical deviations,” as 
in the dry, 


and not in Ehrenberg suggests, it more probably comes from one 
ee place about the vernal, and from another about the 
autumnal equinox ; for places which have their rainy 
season at one equinox have their dry season at the other. 

§278 At the time of the vernal equinox, the valley of the 
Valley of Lower Oronoco is then in its dry season; everything is 


Oronoco parched up with the drought; the pools are dry, and the 


during 


vernal marshes and plains become arid wastes. All vegetation 


equinox 


parched has ceased; the great serpents and reptiles have buried 
pen themselves for hibernation ;* the hum of insect life is 
hushed, and the stillness of death reigns through the valley. 
Under these circumstances, the light breeze, raising 
dust from lakes that are dried up, and lifting motes from 
the brown savannas, will bear them away like clouds in 
the air. 

¢279 ‘This is the period of the year when the surface of the 
see earth in this region, strewed with impalpable and feather- 
bernie light remains of animal and vegetable organisms, is swept 
over by whirlwinds, gales, and tornadoes of terrific force. 
This is the period for the general atmospheric disturbances 
which have made characteristic the equinoxes. Do not 
these conditions appear sufficient to afford the “rain dust” 

for the spring showers ? 


* Humboldt. 
2 § 188. 


RED FOGS AND SEA DUST. 127 


At the period of the autumnal equinox, another por- 
tion of the Amazonian basin is parched with drought, and 
liable to winds that fill the air with dust, and with the 
remains of dead animal and vegetable matter ; these im- 
palpable organisms, which each rainy season calls into 
being, to perish the succeeding season of drought, are 
perhaps distended and made even lighter by the gases of 
decomposition which has been going on in the period of 
drought. 

May not, therefore, the whirlwinds which accompany 
the vernal equinox, and sweep over the lifeless plains of 
the Lower Oronoco, take up the “rain dust” which de- 
scends in the northern hemisphere in April and May? 
and may it not be the atmospherical disturbances which 
accompany the autumnal equinox that take up the micro- 
scopic organisms from the Upper Oronoco and the great 
Amazonian basin for the showers of October ? 

The Baron von Humboldt, in his Aspects of Nature, 
thus contrasts the wet and the dry seasons there : 

“When, under the vertical rays of the never-clouded 
sun, the carbonized turfy covering falls into dust, the 
indurated soil cracks asunder as if from the shock of an 
earthquake. If at such times two opposing currents of 
air, whose conflict produces a rotary motion, come in 
contact with the soil, the plain assumes a strange and 
singular aspect. Like conical-shaped clouds, the points 
of which descend to the earth, the sand rises through the 
rarefied air on the electrically-charged centre of the 
whirling current, resembling the loud water-spout, dreaded 
by the experienced mariner, The lowering sky sheds a 
dim, almost straw-coloured light on the desolate plain. 


CHAPTER 
Vv. 
§ 280 
During 
the autum. 
nal equi- 
nox an- 
other part 
of the 
Amazon- 
jan basin 
is parched 


We | 


May not 
these 
whirl- 
winds take 
up the 
Tain dust. 


282 


ee) 


Contrast 
of the wet 
and dry 
season by 
Von Humes 
boldt. 


CHAPTER 
Vv. 


Contrast 
continued. 


128 THE PHYSICAL GEOGRAPHY OF THE SEA. 


The horizon draws suddenly nearer, the steppe seems to 
contract. and with it the heart of the wanderer. The 
hot, dusty particles which fill the air increase its suffo- 
cating heat, and the east wind, blowing over the long- 
heated soil, brings with it no refreshment, but rather a 
still more burning glow. The pools which the yellow, 
fading branches of the fan-palm had protected from eva- 
poration, now gradually disappear. As in the icy north 
the animals become torpid with cold, so here, under the 
influence of the parching drought, the crocodile and the 
boa become motionless and fall asleep, deeply buried in 
the dry mud..... 

“The distant palm-bush, apparently raised by the in- 
fluence of the contact of unequally heated and therefore 
unequally dense strata of air, hovers above the ground, 
from which it is separated by a narrow intervening mar- 
gin. Half-concealed by the dense clouds of dust, restless 
with the pain of thirst and hunger, the horses and cattle 
roam around, the cattle lowing dismally, and the horses 
stretching out their long necks and snuffing the wind, 
if haply a moister current may betray the neighbourhood 
of a not wholly dried-up pool..... 

“At length, after the long drought, the welcome sea- 
son of the rain arrives; and then how suddenly is the 


“Hardly has the surface of the earth received the re- 
freshing moisture, when the previously barren steppe 
begins to exhale sweet odours, and to clothe itself with 
killingias, the many panicles of the paspulum, and a 
variety of grasses. The herbaceous mimosas, with re- 
newed sensibility to the influence of light, unfold their 


RED FOGS AND SEA DUST. 129 


drooping, slumbering leaves to greet the rising sun; and 
the early song of birds and the opening blossoms of the 
water-plants join to salute the morning.” 

The arid plains and deserts, as well as high moun- 
tain ranges, have, it may well be supposed, an influence 
upon the movements of the great aerial ocean, as shoals 
and other obstructions have upon the channels of circu- 
lation in the sea. The deserts of Asia, for instance, pro- 
duce’a disturbance upon the grand system of atmospheri- 
eal circulation, which, in summer and autumn, is felt in 
Europe, in Liberia, and away out upon the Indian Ocean, 
as far to the south as the equinoctial line. There is an 
indraught from all these regions toward these deserts. 
These indraughts are known as monsoons at sea; on the 
land, as the prevailing winds of the season. 

Imagine the area within which this indraught is felt, 
and let us ask a question or two, hoping for answers. 
The air which the indraught brings into the desert 
places, and which, being heated, rises up there, whither 
does it go? It rises up in a column a few miles high 
and many in circumference, we know, and we can imagine 
that it is like a shaft many times thicker than it is tall, 
but how is it crowned? Is it crowned like the stem of 
a mushroom, with an efflorescence or ebullition of heated 
air flaring over and spreading out in all directions, and 
then gradually thinning out as an upper current, extend- 
ing even unto the verge of the area whence the indraught 
is drawn? If so, does it then descend and return to the 
desert plains as an indraught again? Then these desert 
places would constitute centres of circulation for the mon- 
soon period ; and if they were such centres, whence would 


2 ¢ 203, 


E) 


CHAPTER 


Effects of 
the deserts 
on atmo- 
spherical 
circulation 


§ 284 


Questions 
to be 
answered. 


CSAPTER 


§ 285 


§ 286 


Colour of 
rain dust. 


§ 287 


A clew. 


§ 288 


130 THE PHYSICAL GEOGRAPHY OF THE SEA, 


these winds get the vapour for their rains in Europe and 
Asia? 

Or, instead of the mushroom shape, and the flare at 
the top in all directions from centre to circumference, does 
the uprising column, like one of those submarine foun- 
tains which are said to be in the Gulf Stream off the 
coast of Florida, bubble up and join in with the flow of 
the upper current? The right answers and explanations 
to these questions would add greatly to our knowledge 
concerning the general circulation of the atmosphere. It 
may be in the power of the microscope to give lght 
here. Let us hope. 

The colour of the “rain dust,” when collected in parcels 
and sent to Ehrenberg, is “ brick-red,” or “ yellow ochre;” 
when seen by Humboldt in the air, it was less deeply 
shaded, and is described by him as imparting a “straw 
colour” to the atmosphere. In the search of spider lines 
for the diaphragm of my telescopes, I procured the finest 
and best threads from a cocoon of a mud-red colour; but 
the threads of this cocoon, as seen singly in the diaphragm, 
were of a golden colour; there would seem, therefore, no 
difficulty in reconciling the difference between the colours 
of the rain dust when viewed in little piles by the micro- 
scopist, and when seen attenuated and floating in the wind 
by the great traveller. 

It appears, therefore, that we here have placed in our 
hands a clew, which, attenuated and gossamer-like though 
it at first appears, is nevertheless palpable and strong 
enough to guide us along through the “circuits of the 
wind” even unto “ the chambers of the south.” 

The frequency of the fall of “rain dust” between the 


RED FOGS AND SEA DUST. 151 


parallels of 17° and 25° north, and in the vicinity of the omarres 
Cape Verd Islands, is remarked upon with emphasis by ie 


5 5 ° - Frequency 
the microscopist. It is worthy of remark, because, in of fail of 

= : = * 6 -. rain dust 
connection with the investigations at the Observatory, it pear the 
. = : Cape Verd 
1s significant. Islands. 


The latitudinal limits of the northern edge of the g 289 
north-east trade-winds are variable. In the spring they tatituai 
are nearest to the equator, extending sometimes at this reac 
season not farther from the equator than the parallel of vats 
15° north. 

The breadth of the calms of Cancer is also variable ; § 290 
so also are their limits. The extreme vibration of this Breaath of 
zone is between the parallels of 17° and 38° north, ac- Caiteen, 
cording to the season of the year. eae 

According to the hypothesis suggested by my researches, § 291 
this is the zone in which the upper currents of atmosphere 
that ascended in the equatorial calms, and flowed off to 
the northward and eastward, are supposed to descend. 

This, therefore, is the zone in which the atmosphere that Confrma- 


tion of 
bears the “rain dust,” or “ African sand,” descends to the theory as 


surface; and this, therefore, is the zone, it might be sup- ea 
posed, which would be the most lable to showers of this Pee 
“dust.” This is the zone in which the Cape Verd Islands 

are situated; they are in the direction which theory gives 

to the upper current of air from the Oronoco and Ama- 

zon with its “rain dust,’ and they are in the region of 

the most frequent showers of “rain dust,” all of which, 
though they do not absolutely prove, are nevertheless 
strikingly in conformity with, this theory as to the circu- 

lation of the atmosphere. 

~ It is true that, in the present state of our information, § 292 


1 § 130. 


CHAPTER 


Vv. 


—_— 


§ 293 


Fall of 
rain dust 
always 
occurs in 
same at- 
mospheri- 
cal vein. 


§ 294 


General 

regularit 
of upper 
currents. 


§ 295 


132 THE PHYSICAL GEOGRAPHY OF THE SEA. 


we cannot tell why this “rain dust” should not be gra- 
dually precipitated from this upper current, and descend 
into the stratum of trade-winds, as it passes from the equa- 
tor to higher northern latitudes; neither can we tell why 
the vapour which the same winds carry along should not, 
in like manner, be precipitated on the way; nor why we 
should have a thunder-storm, a gale of wind, or the dis- 
play of any other atmospherical phenomenon to-morrow, 


and not to-day: all that we can say is, that the condi- 


tions of to-day are not such as the phenomenon requires 
for its own development. 

Therefore, though we cannot tell why the “ sea-dust” 
should not fall always in the same place, we may never- 
theless suppose that it is not always in the atmosphere, 
for the storms that take it up occur only occasionally, and 
that when up, and in passing the same parallels, it does 
not, any more than the vapour from a given part of the 
sea, always meet with the conditions—electrical and 
others—favourable to its descent, and that these condi- 
tions, as with the vapour, may occur now in this place, 
now in that. But that the fall does occur always in the 
same atmospherical vein or general direction, my inves- 
tigations would suggest, and Ehrenberg’s researches prove. 

Judging by the fall of sea or rain dust, we may sup- 
pose that the currents in the upper regions of the atmo- 


y : ‘ 
sphere are remarkable for their general regularity, as well 


as for their general direction and sharpness of limits, so to 
speak, 

We may imagine that certain electrical conditions are 
necessary to a shower of “ sea-dust,” as well as to a thun- 
der-storm; and that the interval between the time of the 


RED FOGS AND SEA DUST. isa 


equinoctial disturbances in the atmosphere and the occur- cuaprex 
rence of these showers, though it does not enable us to 3 
determine the true rate of motion in the general system of 
atmospherical circulation, yet assures us that it is not less 

on the average than a certain rate. 

I do not offer these remarks as an explanation with § 296 
which we ought to rest satisfied, provided other proof can Authors 
be obtained; I rather offer them in the true philosophical jaa 
spirit of the distinguished microscopist himself, simply as 
affording, as far as they are entitled to be called an ex- 
planation, that explanation which is most in conformity 
with the facts before us, and which is suggested by the 
results of a novel and beautiful system of philosophical 
research. It is not, however, my province, or that of any 
other philosopher, to dictate belief. Any one may found 
hypotheses if he will state his facts and the reasoning by 
which he derives the conclusions which constitute the 
hypothesis. Having done this, he should patiently wait 
for time, farther research, and the judgment of his peers, 
to expand, confirm, or reject the doctrine which he may 
have conceived it his duty to proclaim. 

Thus, though we have tallied the air, and put labels on g 297 
the wind, to “ tell whence it cometh and whither it another 


Q 5 . agent con- 
goeth,” yet there evidently is an agent concerned in the Ses 


circulation of the atmosphere whose functions are mani- 927 Pn 
fest, but whose presence has never yet been clearly recog- fon: 
nized, 

When the air which the north-east trade-winds bring § 298 
down meets in the equatorial calms that which the south- 
east trade-winds convey, and the two rise up together, 


what is it that makes them cross? Where is the power 


134 THE PHYSICAL GEOGRAPHY OF THE SEA. 


cuarter that guides that from the north over to the south, and 
that from the south up to the north? 

The conjectures in the next chapter as to “the relation 
between magnetism and the circulation of the atmosphere” 
may perhaps throw some light upon the answer to this 
question. 


MAGNETISM AND CIRCULATION OF THE ATMOSPHERE. 135 


CHAPTER. VI. 


ON THE PROBABLE RELATION BETWEEN MAGNETISM AND 
THE CIRCULATION OF THE ATMOSPHERE. 


Faraday’s Discoveries, § 299.—Is there a crossing of Air at the Calm Belts? 
801.—Whence comes the Vapour for Rains in extra-tropical Regions? 305.— 
Significant Facts, 310.—Wet and dry Winds, 311.—Regions of Precipitation 
and Evaporation, 312.—What guides the Wind in his Circulations? 313.— 
Distribution of Rains and Winds not left to Chance, 315.—A Conjecture about 
Magnetism, 318.—Circumstantial Evidence, 328.—More Evaporating Surface 
in the Southern than in the Northern Hemisphere, 326.—Whence come the 
Vapours that feed the great Rivers with Rains? 829.—Rain and Thermal 
Maps, 330.—The Dry Season in California, the Wet in the Mississippi Valley, 
332.—Importanee of Meteorological Observations in British America, 333.— 
Importance of extending the System from the Sea to the Land, 334.— Climate 
of the Interior, 335.—The extra-tropical Regions of the Northern Hemisphere 
Condenser for the Trade-winds of the Southern, 336.—Plate VII., 339.— 
Countries most favourable for having Rains, 343.—How does the Air of the 
North-east and South-east Trades cross in the Equatorial Calms, 350.—Rain 
for the Mississippi Valley, 357.—Blood Rains, 872.—Track of the Passat- 
Staub on Plate VII., 874. —The Theory of Ampére, 378.—Calm Regions about 
the Poles, 380.—The Pole of maximum Cold, 381. 


OXYGEN, philosophers say, comprises one-fifth part of the 
atmosphere, and Faraday has discovered that it is magnetic. 

This discovery presents itself to the mind as a great 
physical fact, which is perhaps to serve as the keystone 
for some of the grand and beautiful structures which phi- 
losophy is building up for monuments to the genius of the 
age. 

Certain facts and deductions elicited in the course of 
these investigations had directed my mind to the work- 
ings in the atmosphere of some agent, as to whose cha- 
racter and nature I was ignorant. Heat, and the diurnal 
rotation of the earth on its axis, were not, it appeared to 
me, sufficient to account for all the currents of both sea 
and air which investigation was bringing to light. 


CHAPTER 
Vi. 


§ 299 
Oxygen is 
magnetic. 


§ 300 


Heat and 

diurnal ro- 
tation not 
sufficient 

to account 
for all the 
enrrents of 
sea and ail 


CHAPTER 
VE 


$301 
Reason to 
suppose 
that the 
trade- 
winds 
crossatthe 
calm belts. 


§ 303 


Evidence 
in favour 
of this sup- 
position. 


156 THE PHYSICAL GEOGRAPHY OF THE SEA. 


For instance, there was reason to suppose that there is 
a crossing of winds at the three calm belts; that is, that 
the south-east trade-winds, when they arrive at the belt 
of equatorial calms and ascend, cross over and continue 
their course as an upper current to the calms of Cancer, 
while the air that the north-east trade-winds discharge 
into the equatorial calm belt continues to go south, as an 
upper current bound for the calms of Capricorn. But 
what should cause this wind to cross over? Why should 
there not be a general mingling in this calm belt of the 
air brought by the two trade-winds, and why should not 
that which the south-east winds convey there be left, after 
its ascent, to flow off either to the north or to the south, 
as chance directs ? 

In the first place, it was at variance with my faith in 
the grand design; for I could not bring myself to believe 
that the operations of such an important machine as the 
atmosphere should be left to chance, even for a moment. 
Yet I knew of no agent which should guide the wind 
across these calm belts, and lead it out always on the 
side opposite to that on which it entered ; nevertheless, 
certain circumstances seemed to indicate that such a ecross- 
ing does take place. 

Evidence in favour of it seemed to be afforded by this 
circumstance, namely, our researches enabled us to trace 
from the belt of calms, near the tropic of Cancer, which 
extends entirely across the seas, an efflux of air both to 
the north and to the south; from the south side of this 
belt the air flows in a never-ceasing breeze, called the 
north-east trade-winds, toward the equator. (Plate L) 

On the north side of it, the prevailing winds come 


Td 


MAGNETISM AND CIRCULATION OF THE ATMOSPHERE, 157 


from it also, but they go toward the north-east. They 
are the well-known south-westerly winds which prevail 
along the route from this country to England, in the ratio 
of two to one. But why should we suppose a crossing to 
take place here? 

We suppose so, because these last-named winds are 
going from a warmer to a colder climate, and therefore it 
may be inferred that nature exacts from them what we 
know she exacts from the air under similar circumstances, 
but on a smaller scale, before our eyes, namely, more pre- 
cipitation than evaporation. 

But where, it may be asked, does the vapour which 
these winds carry along, for the replenishing of the whole 
extra-tropical regions of the north, come from? They did 
not get it as they came along in the upper regions, a 
counter-current to the north-east trades, unless they eva- 
porated the trade-wind clouds, and so robbed those winds 
of their vapour. They certainly did not get it from the 
surface of the sea in the calm belt of Cancer, for they did 
not tarry long enough there to become saturated with 
moisture. Thus circumstances again pointed to the south- 
east trade-wind regions as the place of supply. 

Moreover, these researches afforded grounds for the 
supposition that the air of which the north-east trade- 
winds are composed, and which comes out of the same 
zone of calms as do these south-westerly winds, so far 
from being saturated with vapour at its exodus, is dry; 
for near their polar edge, the north-east trade winds are, 
for the most part, dry winds. Reason suggests, and phi- 
losophy teaches, that, going from a lower to a higher 
temperature, the evaporating powers of these winds are 


CHAPTER 
VI. 


— 


§ 304 


§ 305 


Whence 
comes the 
vapour for 
replenish- 
ing the ex- 
tra-tropi- 
eal regions 


§ 306 


North-east 
trade- 
winds for 
the most 
part dry. 


CHAPTER 
VI. 


§ 307 


By what 
agency is 


138 THE PHYSICAL GEOGRAPHY OF THE SEA. 


increased; that they have to travel, in their oblique 
course toward the equator, a distance of nearly three 
thousand miles; that, as a general rule, they evaporate 
all the time, and all the way, and precipitate little or 
none on their route; investigations have proved that they 
are not saturated with moisture until they have arrived 
fully up to the regions of equatorial calms, a zone of con- 
stant precipitation. 

This calm zone of Cancer borders also, it was perceived, 
upon a rainy region, 

Where does the vapour which here, on the northern 
edge of this zone of Cancer, is condensed into rains, come 


the vapour from ?—and where, also—was the oft-repeated question— 


conveyed 
across the 
calm belt. 


§ 308 


does the vapour which is condensed into rains for the 
extra-tropical regions of the north generally come from ? 
By what agency is it conveyed across this calm belt from 
its birth-place between the tropics # 

I know of no law of nature or rule of philosophy which 
would forbid the supposition that the air which has been 
brought along as the north-east trade-winds to the equa- 
torial calms does, after ascending there, return by the 
counter and upper currents to the calm zone of Cancer, 
here descend and re-appear on the surface as the north- 
east trade-winds again. I know of no agent in nature 
which would prevent it from taking this circuit, nor do I 
know of any which would compel it to take this circuit ; 
but while I know of no agent in nature that would pre- 
vent it from taking this circuit, I know, on the other 
hand, of circumstances which rendered it probable that 
such, in general, is not the course of atmospherical circu- 
lation—that it does not take this circuit. Ispeak of the 


MAGNETISM AND CIRCULATION OF THE ATMOSPHERE. 139 


rule, not of the exceptions; these are infinite, and, for the 
most part, are caused by the land. 

And I moreover know of facts which go to strengthen 
the supposition that the winds which have come in the 
upper regions of the atmosphere from the equator, do not, 
after arriving at the calms of Cancer, and descending, re- 
turn to the equator on the surface, but that they continue 
on the surface toward the pole. But why should they? 
What agent in nature is there that can compel these, ra- 
ther than any other winds, to take such a circuit ? 

The following are some of the facts and circumstances 
which give strength to the supposition that these winds 
do continue from the calm belt of Cancer toward the 
pole as the prevailing south-westerly winds of the extra- 
tropical north : 

We have seen (Plate I.) that, on the north side of this 
calm zone of Cancer, the prevailing winds on the surface 
are from this zone toward the pole, and that these winds 
return as A through the upper regions from the pole; 
that, arriving at the calms of Cancer, this upper current 
A meets another upper current G from the equator, where 
they neutralize each other, produce a calm, descend, and 
come out as surface winds, namely, A as B, or the trade 
winds; and G as H, or the variable winds. 

Now, observations have shown that the winds repre- 
sented by H are rain winds; those represented by B, dry 
winds; and it is evident that A could not bring any 
vapours to these calms to serve for H to make rains of ; 
for the winds represented by A have already performed 
the circuit of surface winds as far as the pole, during 
which journey they parted with all their moisture, and, 


CHAPTER 
VI. 


§ 309 


There 

are facts 
which 
strengthen 
the suppo- 
sition that 
the winds 
cross. 


§ 310 


Some of 
the facts. 


§ 311 


Wet and 
dry winds 


140 THE PHYSICAL GEOGRAPHY OF THE SEA. 


carter returning through the upper regions of the air to the 

“calm belt of Cancer, they arrived there as dry winds. 
The winds represented by B are dry winds; therefore 
it was supposed that these are but a continuation of the 
winds A. 

§ 312 On the other hand, if the winds A, after descending, 
Noevapo- do turn about and become the surface winds H, they 
resionon would first have to remain a long time in contact with 
ride of the the sea, in order to be supplied with vapour enough to 
Ganeer. feed the great rivers, and supply the rains for the whole 

earth between us and the north pole. In this case we 
should have an evaporating region on the north as well 
as on the south side of this zone of Cancer; but investi- 
gation shows no such region; I speak exclusively of the 
ocean. 

$313 Hence it was inferred that A and G do come out on 

the surface as represented by Plate I. But what is the 

agent that should lead them out by such opposite paths ? 

¢ 314 According to this mode of reasoning, the vapours which 
supply the rains for H would be taken up in the south- 

east trade-wind region by F, and conveyed thence along 

the route G to H. And if this mode of reasoning be 
Conjecture admitted as plausible—if it be true that G have the 
eacae vapour which, by condensation, is to water with showers 
“tthe extra-tropical regions of the northern hemisphere, 
Nature, we may be sure, has provided a guide for con- 
ducting G across this belt of calms, and for sending it on 

in the right way. Here it was, then, at this crossing of 

the winds, that I thought I first saw the foot-prints of 

an agent whose character I could not comprehend. Could 


it be the magnetism that resides in the oxygen of the air? 


MAGNETISM AND CIRCULATION OF THE ATMOSPHERE. 141 


Heat and cold, the early and the latter rain, clouds and 
sunshine, are not, we may rely upon it, distributed over 
the earth by chance; they are distributed in obedience to 
laws that are as certain and as sure in their operations as 
the seasons in their rounds. If it depended upon chance 
whether the dry air should come out on this side or on 
that of this calm belt, or whether the moist air should 
return or not whence it came—if such were the case in 
nature, we perceive that, so far from any regularity as to 
seasons, we should have, or might have, years of droughts 
the most excessive, and then again seasons of rains the 
most destructive; but, so far from this, we find for each 
place a mean annual proportion of both, and that so regu- 
lated withal, that year after year the quantity is preserved 
with remarkable regularity. 

Having thus shown that there is no reason for suppos- 
ing that the upper currents of air, when they meet over 
the calms of Cancer and Capricorn, are turned back to 
the equator, but having shown that there is reason for 
supposing that the air of each current, after descending, 
continues on in the direction towards which it was tra- 
velling before it descended, we may go farther, and, by a 
similar train of circumstantial evidence, afforded by these 
researches and other sources of information, show that the 
air, kept in motion on the surface by the two systems of 
trade-winds, when it arrives at the belt of equatorial 
calms, and ascends, continues on thence, each current to- 
ward the pole which it was approaching while on the 
surface. 

In a problem like this, demonstration in the positive 
way is difficult, if not impossible. We must rely for our 


CHAPTER 
WA 
§ 315 
Distribu- 
tion of 
rain and 
wind not 
left to 
chance. 


§ 316 


No reason 
for suppos- 
ing the 
winds turn 
back to the 
equator. 


§ 317 


142 THE PHYSICAL GEOGRAPHY OF THE SEA. 


ces proof upon philosophical deduction, guided by the lights 

— of reason; and in all cases in which positive proof can- 

not be adduced, it is permitted to bring in circumstantial 
evidence. 

§318 Iam endeavouring, let it be borne in mind, to show 

Cause for cause for the conjecture that the magnetism of the oxygen 


conjectur- 
ingthe of the atmosphere is concerned in conducting the air which 


ee has blown as the south-east trade-winds—and after it has 

“arrived at the belt of equatorial calms and risen up— 
over into the northern hemisphere, and so on through its 
channels of circulation, as traced on Plate I. 

§ 319 But, in order to show reasonable grounds for this con- 
Een jecture, I want to establish, by circumstantial evidence 
evidence. and such indirect proof as my investigations afford, that 

such is the course of the “ wind in his circuits,” and that 
the winds represented by F, Plate L, do become those 
represented by G, H, A, B, C, D, and E successively. 
¢320 In the first place, F represents the south-east trade- 
The atmo- Winds—.é., all the winds of the southern hemisphere as 
Ses they approach the equator; and is there any reason for 
one hemi. SUpposing that the atmosphere does not pass freely from 
pen OnE hemisphere to another? On the contrary, many rea- 
sons present themselves for supposing that it does. 

§ 321 If it did not, the proportion of land and water, and 
Its effect consequently of plants and warm-blooded animals, being 
didnt, So different in the two hemispheres, we might imagine 

that the constituents of the atmosphere in them would, 
in the course of ages, probably become different, and that 
consequently, in such a case, man could not safely pass 
from one hemisphere to the other. 


322 Consider the manifold beauties in the whole system of 


Ze) 


MAGNETISM AND CIRCULATION OF THE ATMOSPHERE 143 


terrestrial adaptations; remember what a perfect and 
wonderful machine’ is this atmosphere ; how exquisitely 
balanced and beautifully compensated it is in all its parts. 
We know that it is perfect; that in the performance of 
its various offices it is never left to the guidance of chance 
—no, not for a moment. Therefore I was led to ask 
myself why the air of the south-east trades, when arrived 
at the zone of equatorial calms, should not, after ascend- 
ing, rather return to the south than go on to the north ? 
Where and what is the agency by which its course is 
decided ? 

Here I found circumstances which again induced me 
to suppose it probable that it neither turned back to the 
south nor mingled with the air which came from the 
regions of the north-east trades, ascended, and then flowed 
indiscriminately to the north or the south. 

But I saw reasons for supposing that what came to the 
equatorial calms as the south-east trade-winds continued 
to the north as an upper current, and that what had 
come to the same zone as north-east trade-winds ascended 
and continued over into the southern hemisphere as an 
upper current, bound for the calm zone of Capricorn. 

And these are the principal reasons and conjectures 
upon which these suppositions were based: 


CHAPTER 
VI. 


Perfect 
machinery 
of the at- 
mosphere. 


§ 323 


§ 324 


Supposi- 
tion. 


' At the seasons of the year when the area covered by § 325 


the south-east trade-winds is large, and when they are 


pares 


evaporating most rapidly in the southern hemisphere, precipita 
ti 
even up to the equator, the most rain is falling in the i 


northern. Therefore it is fair to suppose that much of 
the vapour which is taken up on that side of the equator 
is precipitated on this. 


2 § 169, 


CHAFTER 
VI. 


§ 326 
More eya- 
porating 
surface in 
southern 
than north 
ern hemi- 
sphere. 

§ 327 
Tempera- 
ture of 
tropical 
regions 
higher in 
the north- 
ern hemi- 
sphere. 


§ 328 


§ 329 


Whence 
come the 
vapours 
that feed 
the great 
rivers. 


§ 330 


144 THE PHYSICAL GEOGRAPHY OF THE SEA. 


The evaporating surface in the southern hemisphere is 
greater, much greater, than it is in the northern ; still, 
all the great rivers are in the northern hemisphere, the 
Amazon being regarded as common to both; and this fact, 
as far as it goes, tends to corroborate the suggestion as to 
the crossing of the trade-winds at the equatorial calms. 

Independently of other sources of information, my 
investigations also taught me to believe that the mean 
temperature of the tropical regions was higher in the 
northern than in the southern hemisphere ; for they show 
that the difference is such as to draw the equatorial edge 
of the south-east trades far over on this side of the equa- 
tor, and to give them force enough to keep the north- 
east trade-winds out of the southern hemisphere almost 
entirely. 

Consequently, as before stated, the south-east trade- 
winds being in contact with a more extended evaporat- 
ing surface, and continuing in contact with it for a 
longer time or through a greater distance, they would 
probably arrive at the trade-wind place of meeting more 
heavily laden with moisture than the others. 

Taking the laws and rates of evaporation into con- 
sideration, I could find no part of the ocean of the north- 
ern hemisphere from which the sources of the Mississippi, 
the St. Lawrence, and the other great rivers of our hemi- 
sphere could be supplied. 


A regular series of meteorological observations has 


Rain mays heen carried on at the military posts of the United 


States since 1819. Rain maps of the whole country* 
have been prepared from these observations by Mr. Lorin 


* See Army Meteorological Observations, published 18565. 


MAGNETISM AND CIRCULATION OF THE ATMOSPHERE. 145 


Blodget at the surgeon general’s office, and under the OHAPTER 
direction of Dr. Cooledge, U.S. A. These maps, as far —— 
as they go, sustain these views in a remarkable manner ; 
for they bring out facts in a most striking way to show 
that the dry season in California and Oregon is the wet 
season in the Mississippi Valley. 

The winds coming from the south-west, and striking g 331 
upon the coasts of California and Oregon in winter, pre- wera 


cipitate there copiously. They then pass over the moun- gons in 
tains robbed in part of their moisture. Of course, after 


California 
and Missis- 
sippi Val- 


watering the Pacific shores, they have not as much vapour {2 


to make rains of, especially for the upper Mississippi 
Valley, as they had in the summer time, when they dis- 
pensed their moisture, in the shape of rains, most sparingly 
upon the Pacific coasts. 

According to these views, the dry season on the Pacific § 332 
slopes should be the wet, especially in the upper Mis- 
sissippi Valley, and vice versa. Blodget’s maps show 
that such is actually the case. 

Meteorological observations in the “ Red River country,” § 333 
and other parts of British America, would throw farther 
light, and give farther confirmation, I doubt not, both to 
these views and to this interesting question. 

These army observations, as expressed in Blodget’s § 334 
maps, reveal other interesting features also, touching the teers 
physical geography of the country. I allude to the two 
isothermal lines 45° and 65°) which include between them 
all places that have a mean annual temperature between 
45° and 65°. 

I have drawn similar lines on the authority of Dove § 335 
and Johnston (A. K., of Edinburgh), across Europe and 


1 Plate VIII. 
10 


146 THE PHYSICAL GEOGRAPHY OF THE SEA. 


caarrer Asia, for the sake of comparison. The isotherm of 657 
“skirts the northern limits of the sugar-cane, and separates 
the inter-tropical from the extra-tropical plants and pro- 

Climates ductions. I have drawn these two lines across America, 


not to be 
reckoned gnd the result shows how much we err when we reckon 


according 


borane climates accord to parallels of latitude. The space that 
these two isotherms of 45° and 65° comprehend between 

the Mississippi and the Rocky Mountains, owing to the 
singular effect of those mountains upon the climate, is 

larger than the space they comprehend between the Mis- 
sissippi and the Atlantic. 
Hyetographically it is also different, being dryer, and 
possessing a purer atmosphere. In this grand range of 
climate between the meridians of 100° and 110° W., the 
amount of precipitation is just about one half of what it is 
between those two isotherms east of the Mississippi. In 

this new country west of it, winter is the dry, and spring 

Hum- the rainy season. It includes the climates of the Caspian 


boldt’s 


opinion Sea, which Humboldt regards as the most salubrious in 
of the 


climates the world, and where he found the most delicious fruits 
bigia’ that he saw during his travels. Such was the purity of 
— the air there, that polished steel would not tarnish even 
by night exposure. These two isotherms, with the re- 
markable loop which they make to the north-west, beyond 
the Mississippi, embrace the most choice climates for the 
olive, the vine, and the poppy; for the melon, the peach, 
and almond. The finest of wool may be grown there, 
and the potato, with hemp, tobacco, maize, and all the 
cereals, may be cultivated there in great perfection. No 
climate of the temperate zone will be found to surpass in 


salubrity that of this Piedmont trans-Mississippi country. 


MAGNETISM AND CIRCULATION OF THE ATMOSPHERE. 147 


By such trains of thought and reasoning as are here omaprer 
. VI. 
sketched, and by such facts and circumstances as are — 


6 
stated above, I have been brought to regard the extra- baie 
tropical regions of the northern hemisphere as standing in Pic@! te 
‘S) = gions of 
the relation of a condenser to a grand steam machine, the eee 
condenser 
boiler of which is in the region of the south-east trade- feine 
rade- 
winds, and to consider the trade-winds of this hemisphere winds ot 


‘ 3 A , the south- 
as performing the like office for the regions beyond Capri- ern nemi- 


sphere. 
corn. 

The calm zone of Capricorn is the duplicate of that of g 337 
Cancer, and the winds flow from it as they do from that, caim 
both north and south; but with this difference: that on“ 
the polar side of the Capricorn belt they prevail from the 
north-west instead of the south-west, and on the equa- 
torial side from the south-east instead of the north-east. 

Now, if it be true that the vapour of the north-east § 338 
trade-winds is condensed in the extra-tropical regions of Mea ee 
the southern hemisphere, the following path, on account of pene 
the effect of diurnal rotation of the earth upon the course sphere. 
of the winds, would represent the mean circuit of a por- 
tion of the atmosphere moving according to the general 
system of its circulation over the Pacific Ocean, namely, 
coming down from the north as an upper current, and 
appearing on the surface of the earth in about longitude 
120° west, and near the tropic of Cancer, it would here 
commence to blow the north-east trade-winds of that 
region. 

To make this clear, see Plate VII., on which I have g 339 
marked the course of such vapour-bearing winds ; A being course of 


a breadth or swath of winds in the north-east trades; B, ee 


. ind 
the same wind as the upper and counter-current to the ""~ 


1 § 168. 


148 THE PHYSICAL GEOGRAPHY OF THE SEA. 


cnaprer south-east trades; and ©, the same wind after it has 
“descended in the calm belt of Capricorn, and come out on 
the polar side thereof, as the rain-winds and prevailing 
north-west winds of the extra-tropical regions of the 
south-western hemisphere. 

§340 This, as the north-east trades, is the evaporating wind. 
North-east AS the north-east trade-wind, it sweeps over a great waste 
wind of waters lying between the tropic of Cancer and the 

equator. 

§341 Meeting no land in this long oblique track over the 
Its route tepid waters of a tropical sea, 1t would, if such were its 

route, arrive somewhere about the meridian of 140° or 
150° west, at the belt of equatorial calms, which always 
divides the north-east from the south-east trade-winds. 
Here, depositing a portion of its vapour as it ascends, it 
would, with the residuum, take, on account of diurnal 
rotation, a course in the upper region of the atmosphere 
to the south-east, as far as the calms of Capricorn. Here 
it descends and continues on toward the coast of South 
America, in the same direction, appearing now as the pre- 
vailing north-west wind of the extra-tropical regions of 
the southern hemisphere. Travelling on the surface from 
warmer to colder regions, it must, in this part of the cir- 
cuit, precipitate more than it evaporates. 

§ 342 Now, it is a coincidence, at least, that this is the route 
Coincid- by which, on account of the land in the northern hemi- 
as sphere, the north-east trade-winds have the fairest sweep 

over that ocean. This is the route by which they are 
longest in contact with an evaporating surface; the 
route by which all circumstances are most favourable to 
complete saturation ; and this is the route by which they 


MAGNETISM AND CIRCULATION OF THE ATMOSPHERE, 149 


can pass over into the southern hemisphere most heavily cuaprza 
laden with vapours for the extra-tropical regions of that Ze 
half of the globe; and this is the supposed route which 

the north-east trade-winds of the Pacific take to reach 

the equator, and to pass from it. 

Accordingly, if this process of reasoning be good, that § 343 
portion of South America between the calms of Capricorn Region of 
and Cape Horn, upon the mountain ranges of which this eral 
part of the atmosphere, whose circuit I am considering as 
a type, first impinges, ought to be a region of copious 
precipitation. 

Now, let us turn to the works on Physical Geography, § 344 
and see what we can find upon this subject. In Berghaus Patagonia. 
and Johnston—department Hyetography— it is stated, 
on the authority of Captain King, R.N., that upward of 
twelve feet (one hundred and fifty-three inches) of rain fell 
in forty-one days on that part of the coast of Patagonia 
which lies within the sweep of the winds just described. 

So much rain falls there, navigators say, that they some- 
times find the water on the top of the sea fresh and sweet. 

After impinging upon the cold hill-tops of the Pata- g 345 
gonian coast, and passing the snow-clad summits of the Becomes a 
Andes, this same wind tumbles down upon the eastern ae 
slopes of the range as a dry wind; as such, it traverses aes 
the almost rainless and barren regions of cis-Andean Pata- 
gonia and South Buenos Ayres. 

These conditions, the direction of the prevailing winds, § 346 
and the amount of precipitation, may be regarded as evi- Bridence 
dence afforded by nature, if not in favour of, certainly not of conjec 
against, the conjecture that such may have been the nik 


voyage of this vapour through the air. At any rate, 


150 THE PHYSICAL GEOGRAPHY OF THE SEA. 


cuapren here is proof of the immense quantity of vapour which 
these winds of the extra-tropical regions carry along with 
them toward the poles; and I can imagine no other place 
than that suggested, whence these winds could get so 

much vapour. 

Theory. I am not unaware of the theory, or of the weight 
attached to it, which requires precipitation to take place 
in the upper regions of the atmosphere on account of the 
cold there, irrespective of proximity to mountain tops and 
snow-clad hills. 

§347 But the facts and conditions developed by this system 

Facts irre- of research upon the high seas are in many respects irre- 


concil- 


amet concileable with that theory. With a new system of facts 


before me, I have, independent of all preconceived notions 
and opinions, set about to seek among them for explana- 
tions and reconciliations. 


§ 348 These may not in all cases be satisfactory to every one; 


How do 
the cur- 


rentsof dence that has already been brought to show that the air 


air cross 


eachother which the north-east and the south-east trade-winds. 
discharge into the belts of equatorial calms, does, in 


indeed, notwithstanding the amount of circumstantial evi- 


ascending, cross—that from the southern passing over 
into the northern, and that from the northern passing 
over into the southern hemisphere (see F and G, B and 
C, Plate I.)—yet some have implied doubt by asking the 
question, “ How are two such currents of air to pass each 
other?” And, for the want of light upon this point, the 
correctness of reasoning, facts, inferences, and deductions 
have been questioned. 

§ 349 In the first place, it may be said in reply, the belt of 


Breadth of . 5 s 
calm belt, equatorial calms is often several hundred miles across, 


MAGNETISM AND CIRCULATION OF THE ATMOSPHERE. 151 


seldom less than sixty ; whereas the depth of the volume cuapren 
of air that the trade-winds pour into it is only about three nest 
miles, for that is supposed to be about the height to which ontace: 
the trade-winds extend. ae 
Thus we have the air passing into these calms by an § 350 
opening on the north side for the north-east trades, and Cokin 
another on the south for the south-east trades, having a eon pie 


out inter- 


cross section of three miles vertically to each opening. It fering 
then escapes by an opening upward, the cross section of Moe 
which is sixty or one hundred, or even three hundred 

miles. A very slow motion upward there will carry off 

the air in that direction as fast as the two systems of 
trade-winds, with their motion of twenty miles an hour, 

can pour it in; and that curds or columns of air can 
readily cross each other and pass in different directions 
without interfering the one with the other, or at least to 

that degree which obstructs or prevents, we all know. 

For example, open the window of a warm room in § 351 
winter, and immediately there are two currents of air Masts: 
ready at once to set through it, namely, a current of warm 
air flowing out at the top, and one of cold coming in below. 

But the brown fields in summer afford evidence on a g 352 
larger scale, and in a still more striking manner, of the Striking 
fact that, in nature, columns, or streamlets, or curdles of are 
air do really move among each other without obstruction. 
That tremulous motion which we so often observe above 
stubble-fields, barren wastes, or above any heated surface, 
is caused by the ascent and descent, at one and the same 
time, of columns of air at different temperatures, the cool 
coming down, the warm going up. They do not readily 


commingle, for the astronomer, long after nightfall, when 


152 THE PHYSICAL GEOGRAPHY OF THE SEA. 


cuapter he turns his telescope upon the heavens, perceives and 
—* Jaments the unsteadiness they produce in the sky. 

§ 353 If the air brought down by the north-east trade-winds 
Diferenee differ in temperature (and why not?) from that brought 


perature by the south-east trades, we have the authority of nature 
of trade- 


Benes DOR saying that the two currents would not readily com- 
would pre- 


vent them mingle. Proof is daily afforded that they would not, and 
mingling. there is reason to believe that the air of each current, in 
streaks, or patches, or curdles, does thread its way through 
the air of the other without difficulty. Now, if the air of 
these two currents differs as to magnetism, might not that 
be an additional reason for their not mixing, and for their 

taking the direction of opposite poles after ascending ? 
§ 354 Therefore we may assume it as a postulate which nature 
Assiip- concedes, that there is no difficulty as to the two currents 
of air, which come into those calm belts from different 
directions, crossing over, each in its proper direction, with- 
out mingling. 
§355 Thus, having shown that there is nothing to prevent 
Additional the crossing of the air in these calm belts, I return to 


evidence 


that they the process of reasoning by induction, and offer additional 

~~ circumstantial evidence to prove that such a crossing does 
take place. Let us therefore catechise, on this head, the 
waters which the Mississippi pours into the sea, inquiring 
of them as to the channels among the clouds through 
which they were brought from the ocean to the fountains 
of that mighty river. 

§356 It rains more in the valley drained by that river than 
ee is evaporated from it again. The difference for a year is — 
Valley. the volume of water annually discharged by that river 

into the sea. 


MAGNETISM AND CIRCULATION OF THE ATMOSPHERE, 153 


At the time and place that the vapour which supplies cuaptrs 


this immense volume of water was lifted by the atmos- ae 
307 


an 


phere up from the sea, the thermometer, we may infer, 
stood higher than it did at the time and place where this 
vapour was condensed and fell down as rain in the Mis- 
sissipp1 Valley. 

I looked to the south for the springs in the Atlantic § 358 
which supply the fountains of this river with rain. But nage 
I could not find spare evaporating surface enough for it, come eon 
in the first place; and if the vapour, I could not find the 
winds which would convey it thence to the right place. 

The prevailing winds in the Caribbean Sea and southern $ 359 

parts of the Gulf of Mexico are the north-east trade-winds. 
They have their offices to perform in the river basins of 
inter-tropical America, and the rains which they may 
discharge into the Mississippi Valley now and then are 
exceptions, not the rule. 

The winds from the north cannot bring vapours from ¢ 340 
the great lakes to make rains for the Mississippi, for two seas 
reasons: Ist, The basin of the great lakes receives from the north, 
the atmosphere more water in the shape of rain than they penta 
give back in the shape of vapour. The St. Lawrence 
River carries off the excess. 2d, The mean climate of 
the lake country is colder than that of the Mississippi 
Valley, and therefore, as a general rule, the temperature 
of the Mississippi Valley is unfavourable for condensing 
vapour from that quarter. 

It cannot come from the Atlantic, because the greater g 3¢1 
part of the Mississippi Valley is to the windward of the Nor from 
Atlantic. The winds that blow across this ocean go to are 
Kurope with their vapours; and in the Pacific, from the 


154 THE PHYSICAL GEOGRAPHY OF THE SEA. 


onarter parallels of California down to the equator, the direction 
"of the wind at the surface is from, not toward the basin 
of the Mississippi. Therefore it seemed to be established 
with some degree of probability, or, if that expression be 
too strong, with something like apparent plausibility, that 
the rain winds of the Mississippi Valley do not, as a 
general rule, get their vapours from the North Atlantic 
Ocean, nor from the Gulf of Mexico, nor from the great 
lakes, nor from that part of the Pacific Ocean over which 

the north-east trade-winds prevail. 

§ 362 The same process of reasoning which conducted us’ 
Notuust into the trade-wind region of the northern hemisphere for 
sn the sources of the Patagonian rains, now invites us into 

the trade-wind regions of the South Pacific Ocean to look 
for the vapour springs of the Mississippi. 

$363 Ifthe rain winds of the Mississippi Valley come from 
Reasons. the east, then we should have reason to suppose that their 

vapours were taken up from the Atlantic Ocean and Gulf 
Stream ; if the rain winds come from the south, then the 
vapour springs might, perhaps, be in the Gulf of Mexico; 
if the rain winds come from the north, then the great 
lakes might be supposed to feed the air with moisture for 
the fountains of that river; but if the rains come from 
the west, where, short of the great Pacific Ocean, should 
we look for the place of evaporation ? 

Wondering where, I addressed a circular letter to 
farmers and planters of the Mississippi Valley, requesting 
to be informed as to the direction of their rain winds. 

§364 I received replies from Virginia, Mississippi, Tennessee, 
pera Missouri, Indiana, and Ohio ; and, subsequently, from Col. 
wind. W, A, Bird, Buffalo, New York, who says, “The south- 


1 § 342, 


MAGNETISM AND CIRCULATION OF THE ATMOSPHERE. 155 


west winds are our fair-weather winds; we seldom have cuarrzr 
rain from the south-west.” Buffalo may get much of its —~ 
rains from the Gulf Stream with easterly winds. But I Seen 
speak of the Mississippi Valley ; all the respondents there," “” 
with the exception of one in Missouri, said, “The south- 

west winds bring us our rains,” 


These winds certainly cannot get their vapours from § 365 
the Rocky Mountains, nor from the Salt Lake, for they They can- 


s é not get 

rain quite as much upon that basin as they evaporate eres 
: from Salt 

from it again ; if they did not, they would, in the process Lake or 


. the Rocky 
of time, have evaporated all the water there, and the mountains 


lake would now be dry. 
These winds, that feed the sources of the Mississippi § 366 
with rain, like those between the same parallels upon the These 


winds go 

ocean, are going from a higher to a lower temperature ; froma 
. . Ru eee : . . higher to 

and these winds in the Mississippi Valley, not being in a tower 


- . a tempera- 
contact with the ocean, or with any other evaporating ture. 


surface to supply them with moisture, must bring with 
them from some sea or another that which they deposit. 
Therefore, though it may be urged, inasmuch as the g 367 

winds which brought the rains to Patagonia’came direct 
from the sea, that they therefore took up their vapours 
as they came along, yet it cannot be so urged in this 
case ; and if these winds could pass with their vapours 
from the equatorial calms through the upper regions of 
the atmosphere to the calms of Cancer, and then as surface 
winds into the Mississippi Valley, it was not perceived 
why the Patagonian rain winds should not bring their 
moisture by a similar route. These last are from the 
north-west, from warmer to colder latitudes; therefore, 
being once charged with vapours, they must precipitate 


+ § 344, 


ge Hes 


Alterna- 
tion of 
rainy 
and dry 
seasons. 


§ 368 


§ 369 


American 
Arctic ex- 
pedition. 


{nfusoria 


§ 370 


156 THE PHYSICAL GEOGRAPHY OF THE SEA. 


as they go, and take up less moisture than they deposit. 
The circumstance that the rainy season in the Mississippi 
Valley alternates with the dry season on the coast of 
California and Oregon, indicates that the two regions 
derive vapour for their rains from the same fountains. 

This, however, could be regarded only as circumstantial 
evidence. Not a fact had yet been elicited to prove that 
the course of atmospherical circulation suggested by my 
investigations is the actual course in nature. It is a case 
in which I could yet hope for nothing more direct than 
such conclusions as might legitimately flow from circum- 
stances. 

My friend Lieutenant De Haven was about to sail in 
command of the American Arctic Expedition in search of 
Sir John Franklin. Infusoria are sometimes found in sea- 
dust, rain-drops, hail-stones, or snow-flakes; and if by 
any chance it should so turn out that the locus of any of 
the microscopic infusoria which might be found descending 
with the precipitation of the Arctic regions should be 
identified as belonging to the regions of the south-east 
trade-winds, we should thus add somewhat to the strength 
of the many clews by which we have been seeking to 
enter into the chambers of the wind, and to “tell whence 
it cometh and whither it goeth.” 

It is not for man to follow the “wind in his circuits;” 
and all that could be hoped was, after a close examination 
of all the facts and circumstances which these researches 
upon the sea have placed within my reach, to point out 
that course which seemed to be most in accordance with 
them ; and then, having established a probability, or even 
a possibility, as to the true course of the atmospheric 


1 $ 330. 


MAGNETISM AND CIRCULATION OF THE ATMOSPHERE. 157 


circulation, to make it known, and leave it for future 
investigations to confirm or set aside. 

It was at this stage of the matter that my friend 
Baron von Gerolt, the Prussian minister, had the kindness 
to place in my hand Ehrenberg’s work, “ Passat-Staub 
und Blut-Regen.” 

Here I found the clew which.I hoped, almost against 
hope, De Haven would place in my hands’ from the north 
pole. 

That celebrated microscopist reports that he found 
South American infusoria in the blood-rains and sea-dust 


of the Cape Verd Islands, Lyons, Genoa, and other places’ 


Thus confirming, as far as such evidence can, the indi- 
cations of our observations, and increasing the probability 
that the general course of atmospherical circulation is in 
conformity with the suggestions of the facts gathered 
from the sea as I had interpreted them, namely, that the 
trade-winds of the southern hemisphere, after arriving at 
the belt of equatorial calms, ascend and continue in their 
course toward the calms of Cancer as an upper current 


from the south-west, and that, after passing this zone of 


calms, they are felt on the surface as the prevailing south- 
west winds of the extra-tropical parts of our hemisphere ; 
and that, for the most part, they bring their moisture 
with them from the trade-wind regions of the opposite 
hemisphere. 


CHAPTER 
VI. 


» $371 


Clew 
‘ound in 
Ehren- 
berg’s 
work. 


§ 372 
Blood-rain 
and sea- 
dust. 


§ 373 


Increased 
probabi- 
lity that 
the trade- 
winds 
cross in 
calms of 
Cancer. 


I have marked on Plate VII. the supposed track of the § 374 


“ Passat-Staub,” showing where it was taken up in South pene 


America, as at P, P, and where it was found, as at S, S; 
the part of the line in dots denoting where it was in the 
upper current, and the unbroken line where it was wafted 


1 § 369. 2 § 273, 


of 


the ‘‘ Pas- 
” sat-Staub" 


158 THE PHYSICAL GEOGRAPHY OF THE SEA. 


eusrtes by a surface current; also on the same plate is designated 
= the part of the South Pacific in which the vapour-springs 
for the Mississippi rains are supposed to be. The hands 
(gq) point out the direction of the wind. Where the 
shading is light, the vapour is supposed to be carried by 

an upper current. 

§375 Such is the character of the circumstantial evidence 
Suspicion which induced me to suspect that some agent, whose 
ta office in the grand system of atmospherical circulation is 

neither understood nor recognised, was at work in these 
calm belts. 

§376 Dr. Faraday has shown that, as the temperature of 
Faralay’s oxygen is raised, its paramagnetic force diminishes, being 

resumed as the temperature falls again. 

“These properties it carries into the atmosphere, so 
that the latter is, in reality, a magnetic medium, ever 
varying, from the influence of natural circumstances, in 
its magnetic power. If a mass of air be cooled, it be- 
comes more paramagnetic ; if heated, it becomes less para- 
magnetic (or diamagnetic), as compared with the air in a 
mean or normal condition.” * 

§377 Now, is it not more than probable that here we have, 
ity tne © the magnetism of the atmosphere, that agent which 
mazne- guides the air from the south’ through the calms of Capri- 
ageat. corn, of the equator, and of Cancer, and conducts it into 

the north ; that agent which causes the atmosphere, with 
its vapours and infusoria, to flow above the clouds from 
one hemisphere into the other, and whose footprints had 
become so palpable ? 


* Philosophical Magazine and Journal of Science, 4th Series, No. I., January, 
1851, page 73. 
1 § 373. 


MAGNETISM AND CIRCULATION OF THE ATMOSPHERE. 159 


Taking up the theory of Ampére with regard to the caaprza 
VI. 


§ 378 
Theory of 
the sun, and expanding it in conformity with the dis- 4™*T® 


magnetic polarity induced by an electrical current, accord- 
ing as it passes through wire coiled with or coiled against 


coveries of Faraday and the experiments of a Prussian 
philosopher,” we perceive a series of facts and principles 
which, being applied to the circulation of the atmosphere, 
make the conclusions to which I have been led touching 
these crossings in the air, and the continual “ whirl” of 
the wind in the Arctic regions against, and in the Ant- Beaidennt 
arctic with the hands of a watch, very significant. 

In this view of the subject, we see light springing up § 379 
from various sources, by which the shadows of approach- 
ing confirmation are clearly perceived. One such source 
of light comes from the observations of my excellent Observa- 


friend Quetelet, at Brussels, which show that the great Quetelet a 
electrical reservoir of the atmosphere is in the upper re- 
gions of the air. It is filled with positive electricity, 
which increases as the temperature diminishes. 

May we not look, therefore, to find about the north and § 380 
south magnetic poles these atmospherical nodes or calm Supposed 


calm 
regions which I have theoretically pointed out there? In _resions at 


other words, are not the magnetic poles of the earth in are 
those atmospherical nodes, the two standing in the rela- 
tion of cause and effect, the one to the other? 

This question was first asked several years ago,} and 
I was then moved to propound it by the inductions of 
theoretical reasoning. 


Observers, perhaps, will never reach those inhospitable $ 381 


* Professor Von Feilitzsch, of the University of Griefswald. Philosophicai 
Magazine, January, 1851. 
+ Maury’s Sailing Directions. 


CHAPTER 
VI. 


Opinions 
of Parry 
and Bar- 
Tow. 


Professor 
Coffin’s 
conclusion 


Position of 
the poles. 


Sir David 
Brewster. 


§ 382 
Difficulty 
of defining 
their exact 
position. 


Philoso- 
phers as- 
sign nearly 
the same 
position to 
them all 


160 THE PHYSICAL GEOGRAPHY OF THE SEA. 


regions with their instruments to shed light upon this 
subject ; but Parry and Barrow have found reasons to 
believe in the existence of a perpetual calm about the 
north pole, and, later, Bellot has reported the existence 
of a calm region within the frigid zone. Professor J. H. 
Coffin, in an elaborate and valuable paper* on the 
“WINDS OF THE NORTHERN HEMISPHERE,” arrives by 
deduction at a like conclusion. In that paper he has 
discussed the records at no less than five hundred and 
seventy-nine meteorological stations, embracing a totality 
of observations for two thousand eight hundred and 
twenty-nine years. He places his “ meteorological pole” 
—pole of the winds—near latitude 84° north, longitude 
105° west. The pole of maximum cold, by another school 
of philosophers, Sir David Brewster among them, has been 
placed in latitude 80° north, longitude 100° west; and 
the magnetic pole, by still another school,+ in latitude 73° 
35’ north, longitude 95° 39’ west. 

Neither of these poles is a point susceptible of definite 
and exact position. The polar calms are no more a point 
than the equatorial calms are a line ; and, considering that 
these poles are areas or discs, not points, it is a little 
curious that philosophers in different parts of the world, 
using different data, and following up investigation each 
through a separate and independent system of research, 
and each aiming at the solution of different problems, 
should nevertheless agree in assigning very nearly the 
same position to them all? Are these three poles grouped 
together by chance, or by some physical cause? By the 


* Smithsonian Contributions to Knowledge, vol. vi., 1854, 
+ Gauss. 


MAGNETISM AND CIRCULATION OF THE ATMOSPHERE, 161 


latter undoubtedly. Here, then, we have another of those 
gossamer-like clews, that sometimes seem almost palpable 
enough for the mind, in its happiest mood, to lay hold_of, 
and follow up to the very portals of knowledge, where, 
pausing to knock, we may boldly demand that the cham- 
bers of hidden things be thrown wide open, that we may 
see and understand the mysteries of the winds, the frost, 
and the trembling needle. 

In the polar calms there is’ an ascent of air; if an 
ascent, a diminution of pressure and an expansion; and 
if expansion, a decrease of temperature. Therefore we 
have palpably enough a connecting link here between the 
polar calms and the polar place of maximum cold. Thus 
we establish a relation between the pole of the winds and 
the pole of cold, with evident indications that there is 
also a physical connection between these and the mag- 
netic pole. Here the outcroppings of the relation between 
magnetism and the circulation of the atmosphere again 
appear. 

May we not find in such evidence as this threads, 
attenuated and almost air-drawn though they be when 
taken singly and alone, yet nevertheless proving, when 
brought together, to have a consistency sufficient, with 
the lights of reason, to guide us as we seek to trace the 
wind in his circuits? The winds approach these polar 
calms* by a circular or spiral motion, travelling in the 
northern hemisphere against, and in the southern with, 
the hands of a watch. The circular gales of the northern 
hemisphere are said also to revolve in like manner against 
the hands ofa watch, while those in the southern hemi- 
sphere travel the other way. Now, should not this dis- 


2 $139, 2 § 155, 
1] 


CHAPTER 
Wi. 


A ciew. 


§ 383 

Relation 
between 
the poles 


§ 384 


Evidence 
to guide 
us in 
tracing 
the wind. 


Winds 
approach 
polar 
calms with 
a spiral 
motion. 


162 THE PHYSICAL GEOGRAPHY OF THE SEA. 


caapter covery of these three poles, this coincidence of revolving 
VI. ° . . 
winds, with the other circumstances that have been 


Encour- ° : 
azement brought to light, encourage us to look to the magnetism 
to look at . : ys 
maguet- Of the air for the key to these mysterious but striking 


sm 54 coincidences ? 
§ 385 Indeed, so wide is the field for speculation presented 
Becealae by these discoveries, that we may in some respects regard 
this great globe itself, with its “cups” and spiral wires 
of air, earth, and water, as an immense “pile” and helix, 
which, being excited by the natural batteries in the sea 
and atmosphere of the tropics, excites in turn its oxygen, 
and imparts to atmospherical matter the properties of 
magnetism. 
§ 386 With the lights which these discoveries cast, we see 
Sepposed (Plate I.) why air, which has completed its circuit to the 


effect of 
magnet- whirl* about the Antarctic regions, should then, according 


the trae to the laws of magnetism, be repelled from the south, and 
attracted by the opposite pole toward the north. 
¢387 And when the south-east and the north-east trade-winds 
meet in the equatorial calms of the Pacific, would not 
these magnetic forces be sufficient to determine the course 
of each current, bringing the former, with its vapours of 
the southern hemisphere, over into this, by the courses 
already suggested ? 
$388 This force, and the heat of the sun, would propel it to 
the north. The diurnal rotation of the earth propels it 
to the east; consequently its course, first through the 
upper regions of the atmosphere and then on the surface 
of the earth, after being conducted by this newly-disco- 
vered agent across the calms of Cancer, would be from 


* “Tt whirleth about continually.”—Brsue. 


MAGNETISM AND CIRCULATION OF THE ATMOSPHERE. 163 


the southward and westward to the northward and east- cHaprus 
ward. a 

These are the winds’ which, on their way to the north g§ 3389 
from the South Pacific, would pass over the Mississippi Bains 
Valley, and they appear* to be the rain winds there. asesstunt 
Whence, then, if not from the trade-wind regions of the =~ 
South Pacific, can the vapours for those rains come ? 

According to this view, and not taking into account s 390 
any of the exceptions produced by the land and other ce 
circumstances upon the general circulation of the atmo- 
sphere over the ocean, the south-east trade-winds, which 
reach the shores of Brazil near the parallel of Rio, and 
which blow thence for the most part over the land, 
should be the winds which, in the general course of 
circulation, would be carried, after crossing the Andes 
and rising up in the belt of equatorial calms, toward 
Northern Africa, Spain, and the South of Europe. : 

They might carry with them the infusoria of Ehrenberg,’ § 3/1 
but, according to this theory, they would be wanting in 
moisture. Now, are not those portions of the Old World, 
for the most part, dry countries, receiving but a small 
— amount of precipitation ? 

Hence the general rule. Those countries to the north § 392 
of the calms of Cancer, which have large bodies of land cere 
situated to the southward and westward of them, in the 
south-east trade-wind region of the earth, should have a 
scanty supply of rain, and vice versa. 

Let us try this rule: The extra-tropical part of New § 393 
Holland comprises a portion of land thus situated in the ee 


southern hemisphere. Tropical India is to the northward rue. 
and westward of it; and tropical India is in the north- 


2 § 181, 2 $ 364. 3 § 273. 


CHAPTER 
VI. 


— 


§ 394 
Great pro- 
bability 
that mag- 
netism is 
an agent 
uw) atmo- 
spherical 
circulation 


§ 395 


164 THE PHYSICAL GEOGRAPHY OF THE SEA. 


east trade-wind region, and should give extra-tropical 
New Holland a slender supply of rain. But what modi- 
fications the monsoons of the Indian Ocean may make to 
this rule, or what effect they may have upon the rains 
in New Holland, my investigations in that part of the 
ocean have not been carried far enough for final decision, 
though New Holland is a dry country. Referring back 
to page 80 for what has been already said concerning 
the “ METEOROLOGICAL AGENCIES” of the atmosphere, it 
will be observed that cases are there brought forward 
which afford trials for this rule, every one of which holds 
good. 

Thus, though it be not proved as a mathematical truth 
that magnetism is the power which guides the storm from 
right to left and from left to right, which conducts the 
moist and the dry air each in its appointed paths, and 
which regulates the “wind in his circuits,” yet that it 
is such a power is rendered very probable ; for, under the 
supposition that there is such a crossing of the air at the 
tive calm places, as Plate I. represents, we can reconcile a 
greater number of known facts and phenomena than we 
can under the supposition that there is no such crossing. 
The rules of scientific investigation always require us, 
when we enter the domains of conjecture, to adopt that 
hypothesis by which the greatest number of known facts 
and phenomena may be reconciled ; and, therefore, we are 
entitled to assume, that this crossing probably does take 
place, and to hold fast to the theory so maintaining until 
it is shown not to be sound.” 

That the magnetism of the atmosphere is the agent 
which guides the air across the calm belts, and prevents 


1 § 159. 3 § 1003. 


MAGNETISM AND CIRCULATION OF THE ATMOSPHERE. 165 


that which enters them from escaping on the side upon cuaprea 
which it entered, we cannot, of our own knowledge, ME 
positively affirm. Suffice it to say, that we recognise in eae 
this property of the oxygen of air an agent that, for aught rae 
we as yet know to the contrary, may serve as such a guide; (me. 
and we do not know of the existence of any other agent 

in the atmosphere that can perform the offices which the 
hypothesis requires. Hence the suspicion that magnetism 

and electricity are among the forces concerned in the cir- 


culation of the atmosphere. 


166 THE PHYSICAL GEOGRAPHY OF THE SEA. 


CHAPTER VII. 


CURRENTS OF THE SEA. 


Governed by Laws, § 396.—The Capacity of Water to convey Heat, 399.—The 
Red Sea Current, 404.—The per centum of Salt in Sea Water, 418.—The 
Mediterranean Current, 423.—Under Current from, 424.—Admiral Smyth’s 
Soundings, 426.—Lyell’s Views, 429.—Admiral Smyth’s Views, 436.—Cur- 
rents of the Indian Ocean, 439.—Gulf Stream of the Pacific, 441.—Its resem- 
blance to that of the Atlantic, 442.—An ice-bearing Current between Africa 
and Australia, 449.—Currents of the Pacific, 451.—A Sargossa Sea in the 
Pacific, 452.—Drift-wood upon the Aleutian Islands, 453.—Cold Ochotsk, 454. 
—Humboldt’s Current, 455.—Warm Current in the South Pacific, 456.—Equa- 
torial Currents in the South Pacific, 458.—The Effect of Rain and Evaporation 
upon Currents, 459.—Under Currents of the Atlantic, 461.—Equilibrium of 
the Sea maintained by Currents, 467.—The Brazil Current, 469. 


cuarrer LET us, in this chapter, set out with the postulate that 
the sea, as well as the air, has its system of circulation, 


Wi and that this system, whatever it be, and wherever its 
ofthe sea Channels lie, whether in the waters at or below the sur- 
face, is in obedience to physical laws. The sea, by the 
circulation of its waters, doubtless has its offices to per- 
form in the terrestrial economy ; and when we see the 
currents in the ocean running hither and thither, we feel 
Theymove that they were not put in motion without a cause. On the 


in obedi- 


encetothe contrary, reason assures us that they move in obedience 

nature. to some law of nature, be it recorded down in the depths 

below, never so far beyond the reach of human ken; and 

being a law of nature, we know who gave it, and that 

neither chance nor accident had anything to do with its 
enactment. 

$397 Nature grants us all that this postulate demands, re- 


peating it to us in many forms of expression; she utters 


CURRENTS OF THE SEA. 167 


it in the blade of green grass which she causes to grow in onapren 
. . . . Vil. 
climates and soils made kind and genial by warmth and —— 

: : Nature 
moisture that some current of the sea or air has conveyed proclaims 
: : this. 
far away from under a tropical sun. She murmurs it out 
in the cooling current of the north ; the whales of the sea 

ere . . . . . 
tell of it, and all its inhabitants proclaim it. 
The fauna and the flora of the sea are as much the ¢ 398 


creatures of climate, and are as dependent for their well- The fawa 


and flora 
being upon temperature as are the fauna and the flora of ofthe sca 
" . as depen- 

the dry land. Were it not so, we should find the fish dent on 
. A . : tempera- 

and the algze, the marine insect and the coral, distributed ture as 


equally and alike in all parts of the ocean. The polar che land. 


whale would delight in the torrid zone, and the habitat 
of the pearl oyster would be also under the iceberg, or in 
frigid waters colder than the melting ice. 

Now water, while its capacities for heat are scarcely § 399 
exceeded by those of any other substance, is one of the Watera 
most complete of non-conductors. Heat does not per- ductor. 
meate water as it does iron, for instance, or other good 
conductors. Heat the top of an iron plate, and the bottom 
becomes warm; but heat the top of a sheet of water, as 
in a pool or basin, and that at the bottom remains cool. 

The heat passes through iron by conduction, but to get 
through water it requires to be conveyed by a motion, 
which in fluids we call currents. 

Therefore the study of the climates of the sea involves § 400 


a knowledge of its currents, both cold and warm. They jiiceori:s 


currents 
necessary 


are the channels through which the waters circulate, and 


by means of which the harmonies of old ocean are pre- aro 
served ; climates of 
; the sea. 


Hence, in studying the system of oceanic circulation, § 401 


1 § 70. 2 $76 


CHAPTER 
Vil. 


Assump- 
tion on 
which is 
based the 
system of 
currents. 


§ 402 


Whirl- 
pools. 


Rotatory 
streams in 
English 
Channel 


§ 4038 


Currents 
of the sea 
can run up 
hill. 


Gulf 
Stream 
one of 
these. 


§ 404 


Those run- 
ting into 
the Red 
Sea and 
Mediter- 
ranean are 
the reverse 


168 THE PHYSICAL GEOGRAPHY OF THE SEA. 


we set out with the very simple assumption, namely, that 
from whatever part of the ocean a current is found to 
run, to the same part a current of equal volume is bound 
to return; for upon this principle is based the whole sys- 
tem of currents and counter-currents of the air as well as 
of the water. 

Currents of water, like currents of air, meeting from 
various directions, create gyrations, which in some parts 
of the sea, as on the coast of Norway, assume the appear- 
ance of whirlpools, as though the water were drawn into 
a chasm below. The celebrated Maelstrom is caused by 
such a conflict of tidal or other streams. Admiral 
Beechey, R.N.,* has given diagrams illustrative of many 
“rotatory streams in the English Channel, a number of 
which occur between the outer extremities of the channel 
tide and the stream of the oceanic or parent wave.” “They 
are clearly to be accounted for,” says he, “by the streams 
acting obliquely upon each other.” 

It is not necessary to associate with oceanic currents 
the idea that they must of necessity, as on land, run from 
a higher to a lower level. So far from this being the 
case, some currents of the sea actually run up hill, while 
others run on a level. 

The Gulf Stream is of the first class.’ 

The currents which run from the Atlantic into the 
Mediterranean, and from the Indian Ocean into the Red 
Sea, are the reverse of this. Here the bottom of the cur- 
rent is probably a water-level, and the top an inclined 
plane, running down hill. Take the Red Sea current as 

* See an interesting paper by him on Tidal Streams of the North Sea and 


English Channel, pp. 703; Phil. Transactions, Part ii., 1851. 
2 § 9. 


CURRENTS OF THE SEA. 169 


an illustration. That sea lies, for the most part, within cuaprur 
vil. 


a rainless and riverless district. It may be compared to 
a long and narrow trough. Being in a rainless district, citer 
the evaporation from it is immense; none of the water 
thus taken up is returned to it either by rivers or rains. 
It is about one thousand miles long; it lies nearly north me 
and south, and extends from latitude 13° to the parallel 

of 30° north. 

From May to October, the water in the upper part of § 405 
this sea is said to be two feet lower than it is near the Diference 
mouth.* This change or difference of level is ascribed to it 
the effect of the wind, which, prevailing from the north 
at that season, is supposed to blow the water out. 

But from May to October is also the hot season; it is § 406 
the season when evaporation is going on most rapidly; ane 
and when we consider how dry and how hot the winds to. 
are which blow upon this sea at this season of the year, 
we may suppose the daily evaporation to be immense; 
not less, certainly, than half an inch, and probably twice 
that amount. We know that the waste from canals by 
evaporation, in the summer time, is an element which 
the engineer, when taking the capacity of his feeders into 
calculation, has to consider. With him it isan important 
element; how much more so must the waste by evapora- 
tion from this sea be, when we consider the physical con- 
ditions under which it is placed. Its feeder, the Arabian 7s ?h?*. 
Sea, is a thousand miles from its head; its shores are "> 
burning sands; the evaporation is ceaseless; and none of 
the vapours, which the scorching winds that blow over it 


earry away, are returned to it again in the shape of rains. 


* Johnston’s Physical Atlas. 


170 THE PHYSICAL GEOGRAPHY OF THE SEA. 


cuavrer ‘The Red Sea vapours are carried off and precipitated 


Vil. . . . 

—— elsewhere. The depression in the level of its head waters 

§ 407 
Cause of 
depression 
in its level 


in the summer time, therefore, it appears, is owing to the 
effect of evaporation as well as to that of the wind blow- 
ing the waters back. 

$408 The evaporation in certain parts of the Indian Ocean’ 
Supposed js from three-fourths of an inch to an inch daily. Suppose 


evapo it for the Red Sea in the summer time to average only 
half an inch a day. 

§ 409 Now, if we suppose the velocity of the current which 
Average runs into that sea to average, from mouth to head twenty 
current miles a day, it would take the water fifty days to reach 
into. the head of it. If it lose half an inch from its surface 

by evaporation daily, it would, by the time it reaches 
the Isthmus of Suez, lose twenty-five inches from its 
surface. 

$410 Thus the waters of the Red Sea ought to be lower at 
is waters the Isthmus of Suez than they are at the Straits of Babel- 
sez than mandeb. Independently of the waters forced out by the 
oa wind, they ought to be lower from two other causes, 

namely, evaporation and temperature, for the temperature 
of that sea is necessarily lower at Suez, in latitude 30°, 
than it is at Babelmandeb, in latitude 13°. 

$411 To make it quite clear that the surface of the Red 
str Sea is not a sea level, but is an inclined plane, suppose 

the channel] of the Red Sea to have a perfectly smooth 
and level floor, with no water in it, and a wave ten feet 
high to enter the Straits of Babelmandeb, and to flow up 
the channel at the rate of twenty miles a day for fifty 
days, losing daily, by evaporation, half an inch; it is easy 
to perceive that, at the end of the fiftieth day, this wave 


2 § 38. 


CURRENTS OF THE SEA. 7k 


would not be so high, by two feet (twenty-five inches), as cuarrzs 
it was the first day it commenced to flow. aise 
The top of that sea, therefore, may be regarded as an g 412 
inclined plane, made so by evaporation. 
But the salt water, which has lost so much of its fresh- § 413 
ness by evaporation, becomes salter, and therefore heavier. 
The lighter water at the Straits cannot balance the heavier 
water at the Isthmus, and the colder and salter, and there- 
fore heavier water, must either run out as an under cur- 
rent, or it must deposit its surplus salt in the shape of 
crystals, and thus gradually make the bottom of the Red 
Sea a salt-bed, or it must abstract all the salt from the 
ocean to make the Red Sea brine—and we know that 
neither the one process nor the other is going on. Hence Mrrnce 
we infer that there is from the Red Sea an under or outer unter 
current, as there is from the Mediterranean through the ES 
Straits of Gibraltar, and that the surface waters near 
Suez are salter than those near the mouth of the Red 
Sea. 
And, to show why there should be an outer and under § 414 
current from each of these two seas, let us suppose the Piss 


n of 
case of a long trough, opening into a vat of oil, with a unre and 


partition to keep the oil from running into the trough. rents 
Now suppose the trough to be filled up with wine on 
one side of the partition to the level of the oil on the 
other. The oil is introduced to represent the lighter 
water as it enters either of these seas from the ocean, 
and the wine the same water after it has lost some of its 
freshness by evaporation, and therefore has become salter 
and heavier. Now suppose the partition to be raised, 
what would take place? Why, the oil would run in as 


172 THE PHYSICAL GEOGRAPHY OF THE SEA, 


cuspter aN upper current, overflowing the wine, and the wine 
“* would run out as an under current. 
$415 The rivers which discharge in the Mediterranean are 
Beautiful not sufficient to supply the waste of evaporation, and it 
ame Te by a process similar to this that the salt which is car- 


ee ried in from the ocean is returned to the ocean again; 

biumot were it not so, the bed of that sea would be a mass of 

mes ‘solid salt. The equilibrium of the seas is preserved, 
beyond a doubt, by a system of compensation as exqui- 
sitely adjusted as are those by which the “ music of the 
spheres” is maintained. 

$416 It is difficult to form an adequate conception of the 

immense quantities of solid matter, in solution, which the 
current from the Atlantic carries into the Mediterranean. 
In the abstract log for March 8th, 1855, Mr. William 
Grenville Temple, master of the United States ship Levant, 
homeward bound, has described the indraught there: 

Extract “Weather fine; made 1} pt. lee-way. At noon, 

oa stood in to Almiria Bay, and anchored off the village of 

ae Roguetas. Found a great number of vessels waiting for 
a chance to get to the westward, and learned from them 
that at least a thousand sail are weather-bound between 
this and Gibraltar. Some of them have been so for six 
weeks, and have even got as far as Malaga, only to 
be swept back by the current. Indeed, no vessel has 
been able to get out into the Atlantic for three months 
past.” 

$417. Now, suppose this current, which baffled and beat 
Strong hack this fleet for so many days, ran no faster than two 


current in- 


tothe knots the hour. Assuming its depth to be 400 feet only, 


Mediter- ts ‘ cC A . 5 . 
ranean. and its width seven miles, and that it carried in with it 


CURRENTS OF THE SEA. Vis 


the average proportion of solid matter—say one thirtieth 
—contained in sea water; and admitting these postu- 
lates into calculation as the basis of the computation, it 
appears that salts enough to make no less than 88 cubic 
miles of solid matter, of the density of water, were car- 
ried into the Mediterranean during these 90 days. Now, 
unless there were some escape for all this solid matter, 
which has been running into that sea, not for 90 days 
merely, but for ages, it is very clear that the Mediter- 
ranean would, ere this, have been a vat of very strong 
brine, or a bed of cubic crystals. 

Let us see the results of actual observation upon the 
density of water in the Red Sea and the Mediterranean, 
and upon the under currents that run out from these 
seas. 

Four or five years ago, Mr. Morris, chief engineer of 
the Oriental Company’s steam-ship Ajdaha, collected spe- 
cimens of Red Sea water all the way from Suez to the 
Straits of Babelmandeb, which were afterward examined 
by Dr. Giraud, who reported the following results :* 


Latitude. Longitude. Spec. Grav. Saline Cont. 
D-grees. Degrees. 1000 parts, 
No. 1. Sea at Suez — — 1027 41.0 
No. 2. Gulf of Suez 27.49 33.44 1026 40.0 
No. 3. Red Sea 24.29 36. 1024 39.2 
No. 4 do. 20.55 38.18 1026 40.5 
Now: do: 20.43 40.03 1024 39.8 
No. 6. do. 14.34 42.43 1024 39.9 
No. 7 do. 12.39 44.45 1023 39.2 


These observations agree with the theoretical deduc- 
tions just announced, and show that the surface waters 
at the head are heavier and salter than the surface waters 
at the mouth of the Red Sea. 


* Transact. of the Bombay Geograph. Soc., vol. ix., May 1849 to August 1850. 


CHAPTER 
VII. 
Computa- 
tion as to 
amount of 

salt car- 
ried in by 
this cur- 
Tent. 


$418 


Density of 
water in 
Red Sea 
and Medi- 
terranean. 


§ 419 


Results 
reported 
by Dr. 
Giraud. 


CHAPTER 
VTS 


§ 421 
Tempera- 
ture of air 
between 
Suez and 
Aden. 


Average 
evapora- 
tion, 


Assump- 
tion of Dr. 
Buist. 


§ 422 
Red Sea is 
three 
thousand 
years old. 


§ 423 
Mediter- 
ranean 
currents, 


174 THE PHYSICAL GEOGRAPHY OF THE SEA. 


In the same paper, the temperature of the air between 
Suez and Aden often rises, it is said, to 90°, “and pro- 
bably averages little less than 75° day and night all the 
year round. ‘The surface of this sea varies in heat from 
65° to 85°, and the difference between the wet and dry 
bulb thermometers often amounts to 25°—in the kamsin, 
or desert winds, to from 30° to 40°; the average evapo- 
ration at Aden is about eight feet for the year.” “ Now, 
assuming,” says Dr. Buist, “the evaporation of the Red 
Sea to be no greater than that of Aden, a sheet of water 
eight feet thick, equal in area to the whole expanse of 
that sea, will be carried off annually in vapour ; or, assum- 
ing the Red Sea to be eight hundred feet in depth at an 
average—and this, most assuredly, is more than double 
the fact—the whole of it would be dried up, were no 
water to enter from the ocean, in one hundred years. 
The waters of the Red Sea, throughout, contain some 
four per cent. of salt by weight—or, as salt is a half 
heavier than water, some 2.7 per cent. in bulk—or, in 
round numbers, say three per cent. In the course of 
three thousand years, on the assumptions just made, the 
Red Sea ought to have been one mass of solid salt, if 
there were no current running out.” 

Now we know the Red Sea is more than three thou- 
sand years old, and that it is not filled with salt; and 
the reason is, that as fast as the upper currents bring the 
salt in at the top, the under currents carry it out at the 
bottom. 

MEDITERRANEAN CURRENTS.—With regard to an under 
current from the Mediterranean, we may begin by remark- 
ing that we know that there is a current always setting 


CURRENTS OF THE SEA, Vis 


in at the surface from the Atlantic, and that this is a salt- cmapres 
water current, which carries an immense amount of salt es 
into that sea. We know, moreover, that that sea is not 
salting up; and therefore, independently of the postulate, 


and of observations, we might infer the existence of an Existence 


of an 
under current, through which this salt finds its way out under 

current 
into the broad ocean again.* inferred. 


With regard to this outer and under current, we have 0bvserva- 


tions re- 

observations telling of its existence as long ago as 1712. garding it 
“Tn the year 1712,” says Dr. Hudson, in a paper com- § 424 
municated to the Philosophical Society in 1724, “ Mon- Extract 


from a 


sieur du L’Aigle, that fortunate and generous commander bipey by 
Te A1d- 


of the privateer called the Phoenix, of Marseilles, giving se. 
chase near Ceuta Point to a Dutch ship bound to Holland, 
came up with her in the middle of the Gut between Tariffa 
and Tangier, and there gave her one broadside, which 
directly sunk her, all her men being saved by Monsieur 
du L’Aigle; and a few days after, the Dutch ship, with 


* Dr. Smith appears to have been the first to conjecture this explanation, which 
he did in 1683 (vide Philosophical Transactions), This continual indranght into 
the Mediterranean appears to have been a vexed question among the navigators 
and philosophers even of those times. Dr. Smith alludes to several hypotheses 
which had been invented to solve these phenomena, such as subterraneous vents, 
cavities, exhalation by the sun’s beams, &c., and then offers his conjecture, 
which, in his own words, is, ‘‘ that there is an under current, by which as great 
a quantity of water is carried out as comes flowing in. To confirm which, besides 
what I have said above about the difference of tides in the offing and at the shore 
in the Downs, which necessarily supposes an under current, I shall present you 
with an instance of the like nature in the Baltic Sound, as I received it from an 
able seaman, who was at the making of the trial. He told me that, being there 
in one of the king’s frigates, they went with their pinnace into the mid stream, 
aud were carried violently by the current; that, soon after this, they sunk a 
bucket with a heavy cannon ball to a certain depth of water, which gave a check 
to the boat’s motion; and, sinking it still lower and lower, the boat was driven 
ahead to the windward against the upper current: the current aloft, as he added, 
not being over four or five fathoms deep, and that the lower the bucket was 
let fal, they found the under current the stronger.” 

1 $ 401. 


176 THE PHYSICAL GEOGRAPHY OF THE SEA, 


cnaprer her cargo of brandy and oil, arose on the shore near Tan- 

= gier, which is at least four leagues to the westward of the 

place where she sunk, and directly against the strength of 

the current, which has persuaded many men that there is 

a recurrency in the deep water in the middle of the Gut 

that sets outward to the grand ocean, which this accident 

very much demonstrates ; and, possibly, a great part of 

the water which runs into the Straits returns that way, 

and along the two coasts before mentioned ; otherwise, 

this ship must, of course, have been driven towards Ceuta, 

and so upward. The water in the Gut must be very deep, 

several of the commanders of our ships of war having 

attempted to sound it with the longest lines they could 
contrive, but could never find any bottom.” 

§425 In 1828, Dr. Wollaston, in a paper before the Philo- 

Dr. Wol-  sophical Society, stated that he found the specific gravity 


laston’s 


observa of a specimen of sea water, from a depth of six hundred 

density. and seventy fathoms, fifty miles within the Straits, to 

have a “density exceeding that of distilled water by 

more than four times the usual excess, and accordingly 

leaves, upon evaporation, more than four times the usual 

quantity of saline residuum. Hence it is clear that an 

under current ontward of such denser water, if of equal 

breadth and depth with the current inward near the sur- 

face, would carry out as much salt below as is brought 

in above, although it moved with less than one-fourth 

part of the velocity, and would thus prevent a perpetual 

increase of saltness in the Mediterranean Sea beyond that 
existing in the Atlantic.” 

$426 The doctor obtained this specimen of sea water from 

Captain, now Admiral Smyth, of the English navy, who 


CURRENTS OF THE SEA. Lae 


had collected it for Dr. Marcet. Dr. Marcet died before 
receiving it, and it had remained in the admiral’s hands 
some time before it came into those of Wollaston. 

It may, therefore, have lost something by evaporation; 
for it is difficult to conceive that all the river water, and 
three-fourths of the sea water which runs into the Medi- 
terranean, is evaporated from it, leaving a brine for the 
under current having four times as much salt as the water 
at the surface of the sea usually contains. Very recently, 
M. Coupvent des Bois is said to have shown, by actual 
observation, the existence of an outer and under current 
from the Mediterranean. 

However that may be, these facts, and the statements 


of the Secretary of the Geographical Society of Bombay; 


seem to leave no room to doubt as to the existence of an 
under current both from the Red Sea and Mediterranean, 
and as to the cause of the surface current which flows 
into them. I think it a matter of demonstration. It is 
accounted for" by the salts of the sea. 

Writers whose opinions are entitled to great respect 
differ with me as to the conclusiveness of this demonstra- 
tion. Among these writers are Admiral Smyth, of the 
British navy, and Sir Charles Lyell, who also differ with 
each other. In 1820, Dr. Marcet, being then engaged 
in studying the chemical composition of sea water, the 
admiral, with his usual alacrity for doing “a kind turn,” 
undertook to collect for the doctor specimens of Mediter- 
ranean water from various depths, especially in and about 
the Straits of Gibraltar. Among these was the one’ taken 
fifty miles within the Straits from the depth of six hun- 
dred and seventy fathoms (four thousand and twenty 


1 § 421, * § 413, 8 § 495, 
1Z 


CHAPTER 
vil. 


Observa- 
tion of M. 
Coupvent 
des Bois. 


§ 428 


Factsleave 
no doubt 
as to the 
existence 
ofan under 
current. 


§ 429 


Difference 
of opinion 
in regard 
to it. 


Specimens 
of water 
collected 
by Admi- 
ral Smyth. 


CHAPTER 


§ 430 


Depth in 
the Straits. 


Sir Charles 
Lyell’s de- 
auctions. 


§ 431 
His rea- 
soning not 
conclusive 


178 THE PHYSICAL GEOGRAPHY OF THE SEA. 


feet), which, being four times salter than common sea 
water, left, as we have just seen, no doubt in the mind of 
Dr. Wollaston as to the existence of this under current of 
brine. 

But the indefatigable admiral, in the course of his cele- 
brated survey of the Mediterranean, discovered that, while 
inside of the Straits the depth was upwards of nine hun- 
dred fathoms, yet in the Straits themselves the depth 
across the shoalest section is not more than one hundred 
and sixty* fathoms. 

“Such being the case, we can now prove,” exclaims 
Sir Charles Lyell, “ that the vast amount of salt brought 
into the Mediterranean does not pass out again by the 
Straits; for it appears by Captain Smyth’s soundings, 
which Dr. Wollaston had not seen, that between the 
Capes of Trafalgar and Spartel, which are twenty-two 
miles apart, and where the Straits are shallowest, the 
deepest part, which is on the side of Cape Spartel, is only 
two hundred and twenty fathoms.+ It is therefore evi- 
dent, that if water sinks in certain parts of the Mediter- 
ranean, in consequence of the increase of its specitic 
gravity, to greater depths than two hundred and twenty 
fathoms, it can never flow out again into the Atlantic, 
since it must be stopped by the submarine barrier which 
crosses the shallowest part of the Straits of Gibraltar.” t 

According to this reasoning, all the cavities, the hollows 
and the valleys at the bottom of the sea, especially in 
the trade-wind region, where evaporation is so constant 
and great, ought to be salting up or filling up with brine. 


* «The Mediterranean.” + One hundred and sixty, Smyth. 
t Lyel’s Principles of Geology, p. 334-5, ninth edition. London, 1853. 
1 § 425 
> . 


CURRENTS OF THE SEA, 179 


Is it probable that such a process is actually going on? 
No. 

According to this reasoning, the water at the bottom 
of the great American lakes ought to be salt, for the 
rivers and the rains, it is admitted, bring salts from the 
land continually and empty them into the sea. It is 
also admitted that the great lakes would from this cause 
be salt, if they had no sea drainage. The Niagara river 
passes these river salts from the upper lakes into Ontario, 
and the St. Lawrence conveys them thence to the sea. 
Now the basins or bottoms of all these upper lakes are 
far below the top of the rock over which the Niagara 
pitches its flood. And, were the position assumed by 
this writer correct, namely, that if the water in any of 
these lakes should, in consequence of its specific gravity, 
once sink below the level of the shoals in the rivers and 
straits which connect them, it never could flow out again, 
and consequently must remain there for ever*—were this 
principle physically correct, would not the water at the 
bottom of the lakes gradually have received salt sufficient, 
during the countless ages that they have been sending it 
off to the sea, to make this everlastingly pent-up water 
briny, or at least quite different in its constituents from 
that of the surface? We may presume that the water 
at the bottom of every extensive and quiet sheet of 
water, whether salt or fresh, is at the bottom by reason 
of specific gravity ; but that it does not remain there for 
ever we have abundant proof. If so, the Niagara River 
would be fed by Lake Erie only from that layer of water 
which is above the level of the top of the rock at the 


* See paragraph quoted (p. 178) from “ Lyell’s Principles of Geology.” 


CHAPTER 
Vil. 


§ 432 
What 
would be 
the effects 
on the 
great 
American 
lakes if 
this rea- 
soning 
were cor- 
rect. 


CHAPTER 
VII. 


§ 433 


Assump- 
tion on 
which Sir 
Charles 
Lyell’s 
opinion 
was 


founded. 


Rate at 
which the 
bar of the 
Mississippi 
travels out 
to sea. 


§ 434 


180 THE PHYSICAL GEOGRAPHY OF THE SEA. 


Falls. Consequently, wherever the breadth of that river 
is no greater than it is at the Falls, we should have a 
current as rapid as it is at the moment of passing the 
top of the rock to make the leap. To see that such is 
not the way of Nature, we have but to look at any com- 
mon mill pond when the water is running over the dam. 
The current in the pond that feeds the overflow is scarcely 
perceptible, for “still water runs deep.” Moreover, we 
know it is not such a skimming current as the geologist 
would make, which runs from one lake to another ; for, 
wherever above the Niagara Falls the water is deep, there 
we are sure to find the current sluggish in comparison 
with the rate it assumes as it approaches the Falls; and 
it is sluggish in deep places, rapid in shallow ones, be- 
cause it is fed from below. The common “ wastes” in 
our canals teach us this fact. 

The reasoning of this celebrated geologist appears to 
be founded upen the assumption that when water, in con- 
sequence of its specific gravity, once sinks below the 
bottom of a current where it is shallowest, there is no 
force of traction in fluids, nor any other power, which 
can draw this heavy water up again. If such were the 
case, we could not have deep water immediately inside 
of the bars which obstruct the passage of the great rivers 
into the sea. Thus the bar at the mouth of the Missis- 
sippi, with only fifteen feet of water on it, is estimated 
to travel out to sea at rates varying from one hundred 
to twenty yards a year. 

In the place where that bar was when it was one 
thousand yards nearer to New Orleans than it now is, 
whether it were fifteen years ago or a century ago, with 


CURRENTS OF THE SEA. 181 


only fifteen or sixteen feet of water on it, we have now 
four or five times that depth. As new bars were succes- 
sively formed seaward from the old, what dug up the 
sediment which formed the old, and lifted it up from 
where specific gravity had placed it, and carried it out to 
sea over a barrier not more than a few feet from the sur- 
face? Indeed, Sir Charles himself makes this majestic 
stream to tear up its own bottom to depths far below the 
top of the bar at its mouth. He describes the Mississippi 
as-a river having nearly a uniform breadth to the dis- 
tance of two thousand miles from the sea.* He makes 
it cut a bed for itself out of the soil, which is heavier 
than Admiral Smyth’s deep sea water, to the depth of 
more than two hundred feet+ below the top of the bar 
which obstructs its entrance into the sea. Could not the 
same power which scoops out this solid matter for the 
Mississippi, draw the brine up from the pool in the Medi- 
terranean, and pass it out across the barrier in the 
Straits ? 

The traction of locomotives on rail-roads, and the force 
of that traction, is well understood. Now, have not 
currents in the deep sea power derived from some such 
force? Suppose this under current from the Mediter- 
ranean to extend one hundred and sixty fathoms down, 
so as to chafe the barrier across the Straits. Upon the 
bottom of this current, then, there is a pressure of more 
than fifty atmospheres. Have we not here a source of 


* «From near its mouth at the Balize, a steamboat may ascend for two thou- 
sand miles with scarcely any perceptible difference in the width of the river.” — 
Lyell, p. 263. 

+ ““The Mississippi is continually shifting its course in the great alluvial 
plain, cutting frequently to the depth of one hundred, and even sometimes to the 
depth of two hundred and fifty feet.”—Zyel?, p. 273. 


CHAPTRH2 
Vil. 


New bars 
formed. 


§ 435 


Force of 
traction on 
rail-roads. 


May not 
deep-sea 
currents 
have 
power 
derived 
from a 
like force 


CHAPTER 
VII. 


§ 436 


Admiral 
Smyth's 
pug gestion 


§ 437 


If Sir 
Charles 
Lyell’s 
principle 
be admit- 
ted, the 
harmonies 
of the sei 
bre gone. 


182 THE PHYSICAL GEOGRAPHY OF THE SEA. 


power that would be capable of drawing up, by almost 
an insensibly slow motion, water from almost any depth ? 
At any rate, it appears that the effect of currents by 
traction, or friction, or whatever force, does extend far 
below the level of their beds in shallow places. Were it 
not so—were the brine not drawn out again—it would 
be easy to prove that this indraught into the Mediter- 
ranean has taken, even during the period assigned by Sir 
Charles to the formation of the Delta of the Mississippi 
—one of the newest formations—salt enough to fill up 
the whole basin of the Mediterranean with crystals. 
Admiral Smyth brought up bottom with his briny sample 
of deep sea water (six hundred and seventy fathoms), but 
no salt crystals. 

The gallant admiral—appearing to withhold his assent 
both from Dr. Wollaston in his conclusions as to this 
under current, and from the geologist in his inferences as 
to the effect of the barrier in the Straits—suggests the 
probability that, in sounding for the heavy specimen of 
sea water, he struck a brine spring. But the specimen, 
according to analysis, was of sea water, and how did a 
brine spring of sea water get under the sea but through 
the process of evaporation on the surface, or by parting 
with a portion of its fresh water in some other way ? 

If we admit the principle assumed by Sir Charles 
Lyell, that water from the great pools and basins of the 
sea can never ascend to cross the ridges which form these 
pools and basins, then the harmonies of the sea are gone, 
and we are forced to conclude they never existed. Every 
particle of water that sinks below a submarine ridge is, 
ipso facto, by his reasoning, stricken from the channels 


o> 


C>) 


CURRENTS OF THE SEA. 183 


of circulation, to become thenceforward for ever motionless 
matter. The consequence would be “cold obstruction ” 
in the depths of the sea, and a system of circulation be- 
tween different seas of the waters only that float above 
the shoalest reefs and barriers. I do not believe in the 
existence of any such imperfect terrestrial mechanism, or 
in any such failures of design, To my mind, the proofs 
—the theoretical proofs—the proofs derived exclusively 
from reason and analogy—are as clear in favour of this 
under current from the Mediterranean as they were in 
favour of the existence of Leverrier’s planet before it was 
seen through the telescope at Berlin. 

Now suppose, as Sir Charles Lyell maintains, that none 
of these vast quantities of salt which this surface current 
takes into the Mediterranean find their way out again. 
It would not be difficult to show, even to the satisfaction 
of that eminent geologist, that this indraught conveys 
salt away from the Atlantic faster than all the fresh-water 
rivers empty fresh supplies of salt into the ocean. Now, 
besides this drain, vast quantities of salts are extracted 
from sea water for madrepores, coral reefs, shell banks, 
and marl beds; and by such reasoning as this, which is 
perfectly sound and good, we establish the existence of 
this under current, or else we are forced to the very un- 
philosophical conclusion that the sea must be losing its 
salts, and becoming less and less briny. 

THE CURRENTS OF THE INDIAN OCEAN. 
examining the physical features of this sea; and study- 


By carefully 


ing its conditions, we are led to look for warm currents 
that have their genesis in this ocean, and that carry from 
it volumes of overheated water, probably exceeding in 


1 Plates VIII and IX. 


CHAPTER 
WIT: 


— 


Author's 
opinion. 


Salt is 
extracted 
from sea- 
water for 
the forma- 
tion of 
shells, 
corals, &¢ 


§ 439 


Warm curs 
Tents in 
Indian 
Ocean. 


Facts 
show their 
existence 


Mozam- 
bique 
current. 


§ 441 
Another 
current 
escapes 
through 
the Straits 
of Malacca 


§ 442 


Points of 
resem- 
blance be- 
tween this 
current 
and the 
Gulf 
Stream. 


184 THE PHYSICAL GEOGRAPHY OF THE SEA. 


quantity many times that which is discharged by the 
Gulf Stream from its fountains (Plate VI.). 

The Atlantic Ocean is open at the north, but tropical 
countries bound the Indian Ocean in that direction. 
The waters of this ocean are hotter than those of the 
Caribbean Sea, and the evaporating force there’ is much 
greater. That it is greater we might, without observa- 
tion, infer from the fact of a higher temperature and a 
greater amount of precipitation on the neighbouring 
shores.* These two facts, taken together, tend, it would 
seem, to show that large currents of warm water have 
their genesis in the Indian Ocean. One of them is the 
well-known Mozambique current, called at the Cape of 
Good Hope the Lagullas current. 

Another of these currents makes its escape through 
the Straits of Malacca, and, being joined by other warm 
streams from the Java and China Seas, flows out into 
the Pacific, like another Gulf Stream, between the Philip- 
pines and the shores of Asia. Thence it attempts the 
great circle route*for the Aleutian Islands, tempering cli- 
mates, and losing itself in the sea on its route toward the 
north-west coast of America. 

Between the physical features of this current and the 
Gulf Stream of the Atlantic there are several points of 
resemblance. Sumatra and Malacca correspond to Florida 
and Cuba; Borneo to the Bahammas, with the Old Provi- 
dence Channel to the south, and the Florida pass to the 
west. The coasts of China answer to those of the United 
States, the Philippines to the Bermudas, the Japan Islands 
to Newfoundland. As with the Gulf Stream, so also 
here with this China current, there is a counter-current 


1 § 210. 2g 202, 2 § 53. 


CURRENTS OF THE SEA. 185 


of cold water between it and the shore. The climates of cuaprex 
the Asiatic coast correspond with those of America along vat 
the Atlantic, and those of Columbia, Washington, and 
Vancouver, are duplicates of those of Western Europe 

and the British Islands; the climate of California (State) 
resembling that of Spain; the sandy plains and rainless 
regions of Lower California reminding one of Africa, with 

its deserts between the same parallels, &c. 

Moreover, the North Pacific, like the North Atlantic, § 443 
is enveloped, where these warm waters go, with mists eons an3 
and fogs, and streaked with lightning. The Aleutian 
Islands are almost as renowned for fogs and mists as are 
the Grand Banks of Newfoundland. 

A surface current flows north through Behring’s Strait § 444 
into the Arctic Sea; but in the Atlantic the current is Curent 


through 


from, not into the Arctic Sea: it flows south on the sur- Behring’: 
face, north below ; Behring’s Strait being too shallow to rea 
admit of mighty under currents, or to permit the intro- 
duction from the polar basin of any large icebergs into 
the Pacific. 

Behring’s Strait, in geographical position, answers to § 445 
Davis's Strait in the Atlantic; and Alaska, with its Behrine’s 


Strait and 
Aleutian chain of islands, to Greenland. But instead of cnen ys 
comparet 
there being to the east of Alaska, as there is to the east sath those 
of Davis's 


of Greenland, an escape into the polar basin for these Strait. 
warm waters of the Pacific, a shore-line intervenes, and 
turns them down through a sort of North Sea along the 
western coast of the continent toward Mexico. They 
appear here as a cold current. The effect of this body of 
cool water upon the littoral climate of California is very 
marked. Being cool, it gives freshness and strength 


186 THE PHYSICAL GEOGRAPHY OF THE SEA. 


cuarrer to the sea-breeze of that coast in summer time, when the 
piste | cooling sea-breeze” is most grateful. 
$446 These contrasts show the principal points of resem- 
Puss blance and of difference between the currents and aque- 


carents ous circulation in the two oceans. The ice-bearing cur- 
oft Nor 


Atiantic rents of the North Atlantic are not repeated as to volume 


wat in the North Pacific, for there is no nursery for ice- 
“5 bergs like the frozen ocean and its arms. The seas of 
Okotsk and Kamschatka alone, and not the frozen seas 

of the Arctic, cradle the icebergs for the North Pacific. 
$447 There is, at times at least, another current of warm 
Current water from the Indian Ocean. It finds its way south 


of warm 


water midway between Africa and Australia, and appears to 


from the 


Indian lose itself in a sort of Sargasso Sea, thinly strewed with 

>: patches of weed. The whales also’ give indications of it. 
Nor need we be surprised at such a vast flow of warm 
water as these three currents indicate from the Indian 
Ocean, when we recollect that this ocean’ is land-locked 
on the north, and that the temperature of its waters 
is frequently as high as 90° Fahr. 

§ 448 There must, therefore, be immense volumes of water 
flowing into the Indian Ocean to supply the waste created 
by these warm currents, and the fifteen or twenty feet of 
water that observations’ tell us are yearly carried off from 
this ocean by evaporation. 

§449 On either side of this warm current that escapes from 
iceveat- the inter-tropical parts of the Indian Ocean,’ midway 
rents between Africa and Australia, an ice-bearing current’ is 

found wending its way from the Antarctic regions with 
supplies of cold water to modify climates, and restore the 


aqueous equilibrium in that part of the world. The cur- 


1 Plate LX. 289489. 2888. «$447. © Plate IX. 


CURRENTS OF THE SEA. . 187 


rent that flows up to the west of this weedy sea is the cnarzer 
greatest ice-bearer. Its bergs occasionally interfere with Bee 
vessels bound to Australia by the new route; those of 

the other seldom. The former sometimes drifts its ice as 

far north as the parallel of 40° south. The Gulf Stream 
seldom permits them to get so near the equator as that 

in the North Atlantic, but I have known the ice-bear- Nearest 
ing current which passes east of Cape Horn into the shebon 
South Atlantic to convey its bergs as far as the parallel ey 
of 37° south latitude. This is the nearest approach of 
icebergs to the equator. 

These currents which run out from the inter-tropical § 450 
basin of that immense sea—Indian Ocean—are active P™ 
currents. They convey along immense volumes of water ernts. 
containing vast quantities of salt, and we know that sea 
water enough to convey back equal quantities of salt, 
and salt to keep up supplies for the outgoing currents, 
must flow into or return to the inter-tropical regions 
of the same sea; therefore, if observations were silent 
upon the subject, reason would teach us to look for 
currents here that keep in motion immense volumes of 
water. 

THE CURRENTS OF THE PaciFic.—The contrast has been § 451 
drawn’ between the China or “ Gulf Stream” of the North Come 
Pacific, and the Gulf Stream of the North Atlantic. The Pacific. 
course of the China Stream has never been satisfactorily anes 
traced out. There is’ along the coast of California and 
Mexico, a southwardly movement of waters, as there is 
along the west coast of Africa toward the Cape de Verd 
Islands. 


In the open space west of this southwardly set along g 452 


1 § 442, 2 Plate IX. 


CHAPTER 
Vil. 


Pool in 
Pacific 
similar to 
Sargasso 
Sea. 


§ 453 


Evidence 
regarding 
the China 
Stream. 


§ 454 


Cold cur- 
rent of 
Okotsk. 


188 THE PHYSICAL GEOGRAPHY OF THE SEA. 


the African coast, there is the famous Sargasso Sea, which 
is the general receptacle of the drift-wood and sea-weed 
of the Atlantic. So, in like manner, to the west from 
California of this other southwardly set, lies the pool into 
which the drift-wood and sea-weed of the North Pacific 
are generally gathered, but in small quantities. 

The natives of the Aleutian Islands, where no trees 
grow, depend upon the drift-wood cast ashore there for 
all the timber used in the construction of their boats, 
fishing-tacle, and household gear. Among this timber, 
the camphor-tree, and other woods of China and Japan, 
are said to be often recognised. In this fact we have 
additional evidence touching this China Stream, as to 
which’ but little at best is known. “The Japanese,” says 
Lieutenant Bent,* in a paper read before the American 
Geographical Society, January, 1856, “are well aware of 
its existence, and have given it the name of ‘ Kuro-Siwo,’ 
or Black Stream, which is undoubtedly derived from the 
deep blue colour of its water, when compared with that 
of the adjacent ocean.” From this we may infer*that the 
blue waters of this China Stream also contain more salt 
than the neighbouring waters of the sea. 

THE CoLD CURRENT OF OxotskK.—Inshore of, but coun- 
ter to the China current, along the eastern shores of Asia, 
is found‘ a streak, or layer, or current of cold water answer- 
ing to that between the Gulf Stream and the American 
coast. This current, like its fellow in the Atlantic, is not 
strong enough at all times sensibly to affect the course of 
navigation ; but, like that in the Atlantic, it is the nur- 


* Lieutenant Bent was in the Japan Expedition with Commodore Perry, and 
used the opportunities thus afforded to study the phenomena of this stream. 
1 Plate 1X. 2 $461, 8 § 4. * § 442. 


CURRENTS OF THE SEA. 189 


sery'of most valuable fisheries. The fisheries of Japan 
are quite as extensive as those of Newfoundland, and the 
people of each country are indebted for their valuable 
supplies of excellent fish to the cold waters which the 
currents of the sea bring down to their shores. 
HUMBOLDT’S CURRENT.—The currents of the Pacific are 
but little understood. Among those about which most is 
thought to be known is the Humboldt Current of Peru, 
which the great man whose name it bears was the first to 
discover. It has been traced on Plate IX. according to 
the best information—defective at best—upon the sub- 
ject. This current is felt as far as the equator, miti- 
gating the rainless climate of Peru as it goes, and making 
it delightful The Andes, with their snow-caps, on one 
side of the narrow Pacific slopes of this inter-tropical 
republic, and the current from the Antarctic regions on the 
other, make its climate one of the most remarkable in the 
world ; for, though torrid as to latitude, it is such as to 
temperature that cloth clothes are seldom felt as oppressive 
during any time of the year, especially after nightfall. 
Between Humboldt’s Current and the great equatorial 
flow there is an area which may be called the “ desolate 
region.” It was observed that this part of the ocean was 
rarely visited by the whale, either sperm or right; why, 
it did not appear; but observations asserted the fact. 
Formerly, this part of the ocean was seldom whitened by 
the sails of a ship, or enlivened by the presence of man. 
Neither the industrial pursuits of the sea nor the high- 
ways of commerce called him into it. Now and then a 
roving cruiser or an enterprising whaleman passed that 
way; but to all else it was an unfrequented part of the 


aS 00: 2 Plate 1X, 


CHAPTER 
Vil. 


Fisheries 
of Japan. 


§ 455 
Hum- 


boldt s 
current. 


§ 456 


The 
‘desolate 
region.’ 


190 THE PHYSICAL GEOGRAPHY OF THE SEA. 


cuaprer Ocean, and so remained until the gold-fields of Australia 

Vil, o . 
— and the guano islands of Peru made it a thoroughfare. 
All vessels bound from Australia to South America now 


pass through it, and in the journals of some of them it is 


fllow described as a region almost void of the signs of life in 

™“?* both sea and air. In the South Pacific Ocean especially, 
where there is such a wide expanse of water, sea-birds 
often exhibit a companionship with a vessel, and will 
follow and keep company with it through storm and calm 
for weeks together. Even those kinds, as the albatross 
and Cape pigeon, that delight in the stormy regions of 
Cape Horn and the inhospitable climates of the Antarctic 
regions, not unfrequently accompany vessels into the per- 
petual summer of the tropics. 

tnerecon Lhe sea-birds that join the ship as she clears Australia 


will, it is said, follow her to this region, and then dis- 
appear. Even the chirp of the stormy-petrel ceases to 
be heard here, and the sea itself is said to be singularly 

barren of “ moving creatures that have life.” 
§457 I have, I believe, discovered the existence of a warm 
Awarm eyrrent from the inter-tropical regions of the Pacific, mid- 


current 
discovered way between the American coast and the shore-lines of 


flowing 


fromthe Australia. This region affords an immense surface for 


pl evaporation. No rivers empty into it; the annual fall of 
thePacifie rain, except in the “ Equatorial Doldrums,” is small, and 
the evaporation is all that both the north-east and the 
south-east trade-winds can take up and carry off I 
have marked on Plate IX. the direction of the supposed 
warm water current which conducts these overheated and 
briny waters from the tropics in mid ocean to the extra- 
tropical regions where precipitation is in excess. Here, 
being cooled, and agitated, and mixed up with waters 
that are less salt, these over-heated and over-salted 


2 


CURRENTS OF THE SEA. 191 


waters from the tropics may be replenished and restored 
to their rounds in the wonderful system of oceanic circu- 
lation. 

There are also about the equator in this ocean some 
curious currents which I do not understand, and as to 
which observations are not sufficient yet to afford the 
proper explanation or description. There are many of 
them, some of which, at times, run with great force. On 
a voyage from the Society to the Sandwich Islands, I 
encountered one running at the rate of ninety-six miles 
a day. 

And what else should we expect in this ocean but a 
system of currents and counter-currents apparently the 
most uncertain and complicated? The Pacific Ocean and 
the Indian Ocean may, in the view we are about to take, 
be considered as one sheet of water. This sheet of water 
covers an area quite equal in extent to one half of that 
embraced by the whole surface of the earth ; and, accord- 
ing to Alexander Keith Johnston, who has thus stated 
it in the new edition of his splendid Physical Atlas, the 
total annual fall of rain on the earth’s surface is one hun- 
dred and eighty-six thousand, two hundred and forty 
cubic imperial miles. Not less than three-fourths of the 
vapour which makes this rain comes from this waste of 
waters ; but supposing that only half of this quantity, 7. e., 
ninety-three thousand, one hundred and twenty cubic 
miles of rain falls upon this sea, and that that much, at 
least, is taken up from it again as vapour, this would give 
two hundred and fifty-five cubic miles as the quantity of 
water which is daily lifted up and poured back again into 
this expanse. It is taken up at one place and rained 
down at another, and in this place, therefore, we have 


OHAPTER 
WIT. 


§ 458 


Curious 
currents, 
not under 
stood. 


§ 459 


Complicat- 
ed system 
of currents 


Causes of 
such. 


CHAFTER 
WIE: 


§ 460 


Supposed 
case. 


Atmosphe- 
rical 
agency. 


192 THE PHYSICAL GEOGRAPHY OF THE SEA. 


agencies for multitudes of partial and conflicting currents, 
all, in their set and strength, apparently as uncertain as 
the winds. 

The better to appreciate the operation of such agencies 
in producing currents in the sea, now here, now there, 
first this way, and then that, let us, by way of illus- 
tration, imagine a district of two hundred and fifty-five 
square miles in extent to be set apart, in the midst of 
the Pacific Ocean, as the scene of operations for one day. 
We must now conceive a machine capable of pumping 
up, in the twenty-four hours, all the water to the depth 
of one mile in this district. The machine must not only 
pump up and bear off this immense quantity of water, 
but it must discharge it again into the sea on the same 
day, but at some other place. Now here is a force for 
creating currents that is equivalent in its results to the 
effects that would be produced by bailing up, in twenty- 
four hours, two hundred and fifty-five cubic miles of 
water from one part of the Pacific Ocean, and emptying 
it out again upon another part. The currents that 
would be created by such an operation would overwhelm 
navigation, and desolate the sea; and, happily for the 
human race, the great atmospherical machine which 
actually does perform every day, on the average, all this 
lifting up, transporting, and letting down of water upon 
the face of the grand ocean, does not confine itself to 
an area of two hundred and fifty-five square miles, but 
to an area three hundred thousand times as great; yet, 
nevertheless, the same quantity of water is kept in 
motion, and the currents, in the aggregate, transport as 
much water to restore the eqwlibrium as they would 


CURRENTS OF THE SEA. 193 


have to do were all the disturbance to take place upon 
our hypothetical area of one mile deep over the space of 
two hundred and fifty-five square miles. Now, when 
we come to recollect that evaporation is lifting up, that 
the winds are transporting, and that the clouds are letting 
down every day actually such a body of water, we are 
reminded that it is done by little and little at a place, 
and by hair’s breadths at a time, not by parallelopipedons 
one mile thick—that the evaporation is most rapid and 
the rains most copious, not always at the same place, 
but now here, now there. We thus see actually existing 
in nature a force perhaps quite sufficient to give rise 
to just such a system of currents as that which mariners 
find in the Pacific—currents which appear to rise in mid 
ocean, run at unequal rates, sometimes east, sometimes 
west, but which always lose themselves where they rise, 
namely, in mid ocean. 

UNDER CURRENTS.—Lieutenant J. C. Walsh, in the 
U.S. schooner “Taney,” and Lieutenant 8S. P. Lee, in 
the U. S. brig “ Dolphin,” both, while they were carrying 
on a system of observations in connection with the WIND 
AND CURRENT CHARTS, had their attention directed to 
the subject of submarine currents. 

They made some interesting experiments upon the 
subject. A block of wood was loaded to sinking, and, 
by means of a fishing-line or a bit of twine, let down to 
the depth of one hundred or five hundred fathoms, at 
the will of the experimenter. A small barrel as a float, 
just sufficient to keep the block from sinking farther, 
was then tied to the line, and the whole let go from the 
boat. 

13 


CHAPTER 
WT 


Conclud- 
ing obser: 
vations. 


§ 461 


Under 
currents. 


§ 462 
Experi- 
ment. 


194 THE PHYSICAL GEOGRAPHY OF THE SEA. 


cuaptrR To use their own expressions, “ It was wonderful, 
VII. 
indeed, to see this barrega move off, against wind, and 


§ 463 
surprising 8€a, and surface current, at the rate of over one knot an 


result hour, as was generally the case, and on one occasion as 
much as 1? knots. The men in the boat could not repress 
exclamations of surprise, fer it really appeared as if some 
monster of the deep had hold of the weight below, and 
was walking off with it.”* Both officers and men were 
amazed at the sight. 

§ 464 ‘The experiments in deep-sea soundings have also thrown 
Experi much light upon the subject of under currents. There is 


ments in 


a _ Teason to believe that they exist in all, or almost all parts 
- of the deep sea, for never in any instance yet has the 
deep-sea line ceased to run out, even after the plummet 

had reached the bottom. 

§465 If the line be held fast in the boat, it invariably parts, 
Bounding: showing, when two or three miles of it are out, that the 
broken. under-currents are sweeping against the bight of it with 

what seamen call a swigging force, that no sounding 
twine has yet proved strong enough to withstand. 

§466 Lieutenant J. P. Parker of the United States frigate 
Lieuten- « Conoress,” attempted, in 1852, a deep-sea sounding off 


ant Park- 
ersex- the coast of South America. He was engaged with the 


aie experiment eight or nine hours, during which time a line 
nearly ten miles long was paid out. Night coming on, 
he had to part the line (which he did simply by attempt- 
ing to haul it in) and return on board. Examination 
proved that the ocean there, instead of being over ten 
miles in depth, was not over three, and that the line was 


swept out by the force of one or more under currents. 


* Lieutenant Walsh. 


CURRENTS OF THE SEA, 195 
But in what direction these currents were running is not 
known. 

It may, therefore, without doing any violence to the 
rules of philosophical investigation, be conjectured, that 
the equilibrium of all the seas is preserved, to a greater 
or less extent, by this system of currents and counter- 
currents at and below the surface. 

If we except the tides, and the partial currents of the 
sea, such as those that may be created by the wind, we 
may lay it down as a rule’ that all the currents of the 
ocean owe their origin to the difference of specific gravity 
between sea water at one place and sea water at another; 
for wherever there is such a difference, whether it be 
owing to difference of temperature or to difference of 
saltness, &., it is a difference that disturbs equilibrium, 
and currents are the consequence. The heavier water 
goes toward the lighter, and the lighter whence the hea- 
vier comes; for two fluids differing in specific gravity, 
and standing at the same level, can no more balance each 
other than unequal weights in opposite scales. It is 
immaterial, as before stated, whether this difference of 
specific gravity be caused by temperature, by the matter 
held in solution, or by any other thing; the effect is the 
same, namely, a current. 

That the sea, in all parts, holds in solution the same 
kind of solid matter; that its waters in this place, where 
it never rains, are not salter than the strongest brine ; 
and that in another place, where the rain is incessant, 
they are not entirely without salt, may be taken as evi- 
dence in proof of a system of currents or of circulation in 
the sea, by which its waters are shaken up and kept 


cai 2 § 36. 


CHAPTERS 
VII. 


§ 467 


Conjec- 
ture re- 
garding 
equili- 
brium of 
all seas. 


Rule laid 
down, that 
ocean cur- 
rents owe 
their ori- 
gin to dif- 
ference of 
specific 
gravity of 
sea-water 
at different 
places. 


§ 468 


Proofs 
that wa 
ters of the 
sea are 
shaken up 
and mixed 


196 THE PHYSICAL GEOGRAPHY OF THE SEA. 


cnarrer mixed together as though they were in a phial. More- 
VII, 


over, we may lay it down as a law in the system of 
Every A 3 i 3 * 
ewrent oceanic circulation, that every current in the sea has its 


has its 


counter Counter current; in other words, that the currents of the 

sumer sea are, like the nerves of the human system, arranged 

in pairs; for wherever one current is found carrying off 

water from this or that part of the sea, to the same part 

must some other current convey an equal volume of water, 

or else the first would, in the course of time, cease for the 
want of water to supply it. 

§ 469 CURRENTS OF THE ATLANTIC.—The principal currents 

Curent of the Atlantic have been described in the chapter on the 

Gulf Stream. Besides this, its eddies and its offsets, are 

Equatorial the equatorial current (Plate VI.), and the St. Roque or 

“Brazil current. Their fountain-head is the same. It is in 

the warm waters about the equator, between Africa and 

America. The former, receiving the Amazon and the 

Oronoco as tributaries by the way, flows into the Carib- 

bean Sea, and becomes, with the waters’ in which the 

vapours of the trade-winds leave their salts, the feeder of 

Brazil the Gulf Stream. The Brazil current, coming from the 

me same fountain, is supposed to be divided by Cape St. 

Roque, one branch going to the south under this name,’ 

the other to the westward. This last has been a great 

bugbear to navigators, principally on account of the diffi- 

culties which a few dull vessels falling to leeward of St. 

Roque have found in beating up against it. It was said 

to have caused the loss of some English transports in the 

last century, which fell to leeward of the Cape on a voyage 

to the other hemisphere ; and navigators, accordingly, were 


advised to shun it as a danger. 


1 § 34, 2 Plate IX. 


CURRENTS OF THE SEA. oT. 


e 


This current has been an object of special investigation cuaprss 
. . . Vil. 
during my researches connected with the Wind and Cur- —— 
A é oS Aa 

rent Charts, and the result has satisfied me that it is Seto 


neither a dangerous nor a constant current, notwithstand- ae Bese 
ing older writers. Horsburgh, in his East India Directory, sated 
eautions navigators against it ; and Keith Johnston, in his 

grand Physical Atlas, published in 1848, thus speaks of it :— 

“This current greatly impedes the progress of those Extract 
vessels which cross the equator west of 23° west longi- ree re 
tude, impelling them beyond Cape St. Roque, when they 
are drawn toward the northern coast of Brazil, and can- 
not regain their course till after weeks or months of delay 
and exertion.” 

So far from this being the case, my researches abun- g 471 
dantly prove that vessels which cross the equator five Author's 
hundred miles to the west of longitude 23° have no diffi- regard to 
culty on account of this current in clearing that cape. 1 iG 
receive almost daily the abstract logs of vessels that cross 
the equator west of 30° west, and in three days from 
that crossing they are generally clear of that cape. <A 
few of them report the current in their favour; most of 
them experience no current at all; but, now and then, 
some do find a current setting to the northward and 
westward, and operating against them at the rate of 
twenty miles a day. The intertropical regions of the currents 
Atlantic, like those of the other oceans} abound with con- {fe '™ 


ter-tropi- 
flicting currents, which no researches yet have enabled yet” 
the mariner to unravel so that he may at all times know 
where they are and tell how they run, in order that he 
may be certain of their help when favourable, or sure of 


avoiding them if adverse. 


198 THE PHYSICAL GEOGRAPHY OF THE SEA. 


cnapteR J may here remark, that there seems to be a larger flow 
“of Polar waters into the Atlantic than of other waters from 
Seale it, and I cannot account for the preservation of the equi- 
currents Jibrium of this ocean by any other hypothesis than that 


probably 
helpto which calls in the aid of under currents. They, I have 


preserve 

eqatli- Le doubt, bear an important part in the system of oceanic 
orlum 0 

Atlantic. circulation. 


THE OPEN SEA IN THE ARCTIC OCEAN. 199 


CHAPTER VIII. 


THE OPEN SEA IN THE ARCTIC OCEAN. 


The Habit of Whalemen, § 473.—Right Whales cannot cross the Equator, $75. 
—An Under Current into the Polar Basin, 478.—Indications of a Warm Cli- 
mate, 481.—De Haven’s Water Sky, 482.—The open Sea of Dr. Kane, 484.— 
Drift of an abandoned Ship, 487. 


Ir is the custom among whalers to have their harpoons cuaprer 
. . VIII. 
marked with date and the name of the ship; and Dr. —— 


1 § 473 


Custom 


Scoresby, in his work on Arctic voyages, mentions severa 

instances of whales that have been taken near the Behr- #ers 

ing’s Strait side with harpoons in them bearing the stamp 

of ships that were known to cruise on the Baffin’s Bay 

side of the American continent ; and as, in one or two in- 

stances, a very short time had elapsed between the date 

of capture in the Pacific and the date when the fish must 

have been struck on the Atlantic side, it was argued, whales, it 
is argued, 


therefore, that there was a north-west passage by which phaye prov. 


. . d ist- 
the whales passed from one side to the other, since the once ora 


north-west 
passage. 


stricken animal could not have had the harpoon in him 
long enough to admit of a passage around either Cape 
Horn or the Cape of Good Hope. 

The whale-fishing is, among the industrial pursuits of § 474 
the sea, one of no little importance ; and when the system Whsle 


fishing 
of investigation out of which the “wind and current sse- 

vient [0 
charts” have grown was commenced, the haunts of this scientific 

investiga- 


animal did not escape attention or examination. The tionofthe 
sea. 

log-books of whalers were collected in great numbers, 

and patiently examined, co-ordinated, and discussed, in 


order to find out what parts of the ocean are frequented 


200 .THE PHYSICAL GEOGRAPHY OF THE SEA, 


cuaprer by this kind of whale, what parts by that, and what parts 
ae by neither.’ 
§475 Log-books containing the records by different ships for 
ves hundreds of thousands of days were examined, and the 
examined, Observations in them co-ordinated for this chart. And 
this investigation, as Plate IX. shows, led to the discovery 
that the tropical regions of the ocean are to the right 
whale as a sea of fire, through which he cannot pass, and 
into which he never enters. The fact was also brought 

ees “out that the same kind of whale that is found off the 

concern. shores of Greenland, in Baffin’s Bay, &e., is found also in 

eee the North Pacific, and about Behring’s Strait, and that 
the right whale of the northern hemisphere is a different 
animal from that of the southern. 

$476 Thus the fact was established that the harpooned whales 

did not pass around Cape Horn or the Cape of Good 
Hope, for they were of the class that could not cross the 
Proof of equator. In this way we were furnished with circum- 
hope stantial evidence affording the most irrefragable proof that 


times, there is, at times at least, open water communication 


through ° : ° 
the Arctie through the Arctic Sea from one side of the continent to 


te the other, for it is known that the whales cannot travel 
under the ice for such a great distance as is that from 
one side of this continent to the other. 
$477 But this did not prove the existence of an open sea 
Butoh there ; it only established the existence—the occasional 
proofofan existence, if you please—of a channel through which 
ee whales had passed. Therefore we felt bound to introduce 
other evidence before we could expect the reader to admit 
cour proof, and to believe with us in the existence of an 


open sea in the Arctic Ocean. 


1 See Plate IX. 


THE OPEN SEA IN THE ARCTIC OCEAN. 201 


There is an under current setting from the Atlantic 
through Davis’s Strait into the Arctic Ocean, and there 
is a surface current setting out. Observations have 
pointed out the existence of this under current there, for 
navigators tell of immense icebergs which they have seen 
drifting rapidly to the north, and against a strong surface 
current. These icebergs were high above the water, and 
their depth below, supposing them to be parallelopipeds, 
was seven times greater than their height above. No 
doubt they were drifted by a powerful under current. 

Now this under current comes from the south, where 
it is warm, and the temperature of its waters is perhaps 
not below 82°; at any rate, they are comparatively warm. 
There must be a place somewhere in the Arctic seas where 
this under current ceases to flow north, and begins to 
flow south as a surface current; for the surface current, 
though its waters are mixed with the fresh waters of 
the rivers and of precipitation in the Polar basin, never- 
theless bears out vast quantities of salt, which is furnished 
neither by the rivers nor the rains. 

These salts are supplied by the under current; for as 
much salt as one current brings in, other currents must 
take out, else the Polar basin would become a basin of 
salt; and where the under current transfers its waters to 
the surface, there is, it is supposed, a basin in which the 
waters, as they rise to the surface, are at 30°, or what- 
ever be the temperature of the under current, which we 
know must be above the freezing point, for the current is 
of water in a fluid, not in a solid state. 

An arrangement in nature, by which a basin of con- 
siderable area in the frozen ocean could be supplied by 


CHAPTER 
VAIL, 

§ 478 

Currents 

through 

Davis's 

Strait. 


$ 479 


Place in 
Arctic seas 
where 
under cur- 
rent ceases 
to flow. 


Salt sup- 
plied by 
under 
current. 


§ 480 


202 THE PHYSICAL GEOGRAPHY OF THE SEA. 


charter water coming in at the bottom and rising up at the top, 

— with a temperature not below 30°, or even 28°—the 

freezing point of sea water—would go far to mitigate the 
climate in the regions round about. 

¢ 481 And that there is a warmer climate somewhere in that 

A warm jnhospitable sea, the observations of many of the ex- 


climate 
exists plorers who have visited it indicate. Its existence may 


where in be inferred also from the well known fact that the birds 

Ocean, and animals are found at certain seasons migrating to the 

spore by north, evidently in search of milder climates, The in- 
stincts of these dumb creatures are unerring, and we can 
imagine no mitigation of the climate in that direction, 
unless it arise from the proximity or the presence there 
of a large body of open water. It is another furnace’ in 
the beautiful economy of Nature for tempering climates 
there. 

8482 Relying upon a process of reasoning like this, and the 
Instrue- deductions flowing therefrom, Lieutenant De Haven, when 
riewen- he went in command of the American expedition in search 
Haven, of Sir John Franklin and his companions, was told, in his 

letter of instructions, to look, when he should get well up 
into Wellington Channel, for an open sea to the north- 
ward and westward. He looked, and saw in that direc- 


Captain Penny afterward went there, 


? 


tion a “water sky.’ 

found open water, and sailed upon it. 
§483 The open sea in the Arctic Ocean is probably not 
Orensea always in the same place, as the Gulf Stream* is not 


in Arctic 

Ocean not always in one place. It probably is always where the 

always in ; 

same place Waters of the under current are brought to the surface ; 
and this, we may imagine, would depend upon the free- 


dom of ingress for the under current. Its course may, 


~ 
or 
S. 
ro 
» 
Ww. 
or 
for) 


THE OPEN SEA IN THE ARCTIC OCEAN, 203 


perhaps, be modified more or less by the ice on the sur- 
face, by changes, from whatever cause, in the course or 
velocity of the surface current, for obviously the under 
current could not bring more water into the frozen ocean 
than the surface current would carry out again, either as 
ice or water. 

Every winter, an example of how very close warm 
water in the sea and a very severe climate on the land or 
the ice may be to each other, is afforded to us in the case 
of the Gulf Stream and the Labrador-like climate of New 
England, Nova Scotia, and Newfoundland. In these 
countries, in winter, the thermometer frequently sinks far 
below zero, notwithstanding that the tepid waters of the 
Gulf Stream may be found with their summer tempera- 
ture within one good day’s sail of these very, very cold 
places. 

Dr. Kane reports an open sea north of the parallel of 
82°. To reach it, his party crossed a barrier of ice 80 or 
100 miles broad. Before gaining this open water, he 
found the thermometer to show the extreme temperature 
of—60°. Passing this ice-bound region by travelling 
north, he stood on the shores of an iceless sea, extending 
in an unbroken sheet of water as far as the eye could 
reach toward the pole. Its waves were dashing on the 
beach with the swell of a boundless ocean. The tides 
ebbed and flowed in it, and I apprehend that the tidal 
wave from the Atlantic can no more pass under this icy 
barrier to be propagated in seas beyond, than the vibra- 
tions of a musical string can pass with its notes a fret 
upon which the musician has placed his finger. The swell 
of the sea cannot pass wide fields or extensive barriers of 


CHAPTER 
Vill. 


Close 
proximity 
of warm 
water in 
the sea 
and a cold 
climate on 
land. 


§ 484 


Dr. Kane's 
report of 
open sea. 


Swell of 
sea cannot 
pass wide 
fields of 
ice. 


OHAPTER 
VIII. 


Inference: 
that most 
of regions 
about the 
pole are 
covered 
with deep 
water. 


Conjectur- 
ed nursery 
of the 
whale. 


§ 485 


Character- 
istics of 
Dr. Kane's 
open sea, 


204 THE PHYSICAL GEOGRAPHY OF THE SEA. 


ice, for De Haven, during his long imprisonment and 
drift} found the ice so firm that he observed regularly 
from an artificial horizon placed upon it, and found the 
mercury always “ perfectly steady.” These tides, there- 
fore, must have been born in that cold sea, having their 
cradle about the North Pole. If these statements and 
deductions be correct, then we infer that most, if not all 
the unexplored regions about the pole are covered with 
deep water; for, were this unexpected area mostly land 
or shallow water, it could not give birth to regular tides. 
Indeed, the existence of these tides, with the immense 
flow and drift which annually take place from the Polar 
Seas into the Atlantic, suggests many conjectures concern- 
ing the condition of these unexplored regions. Whale- 
men have always been puzzled as to the place of breed- 
ing for the right whale. It is a cold-water animal, and, 
following up this train of thought, the question is 
prompted, Is the nursery for the great whale in this Polar 
sea, which has been so set about and hemmed in with a 
hedge of ice, that man may not trespass there? This 
providential economy is still farther suggestive, prompt- 
ing us to ask, Whence comes the food for the young 
whales there? Do the teeming waters of the Gulf 
Stream* convey it there also, and in channels so far down 
in the depths of the sea that no enemy may waylay and 
spoil it on the long journey ? 

Seals were sporting and water-fowl feeding in this 
open sea of Dr. Kane’s. Its waves came rolling in at 
his feet, and dashed with measured tread, like the ma- 
jestic billows of old ocean, against the shore. Solitude, 
the cold and boundless expanse, and the mysterious heay- 


THE OPEN SEA IN THE ARCTIC OCEAN. 205 


ings of its green waters, lent their charm to the scene. 
They suggested fancied myths, and kindled in the ardent 
imagination of the daring mariners many longings. 

The temperature of its waters was only 36°! Such 
warm water could get there from the south only as a cur- 
rent far down in the depths below. The bottom of the 
ice of this eighty miles of barrier was no doubt many— 
perhaps hundreds of feet below the surface level. Un- 
der this ice there was also doubtless water above the 
freezing point. 

Nor need the presence of warm water within the 
Arctic circle excite surprise, when we recollect that the 
cold waters of the frigid zone are transferred to the torrid 
without changing their temperature perhaps more than 
7° or 8° by the way. This transfer of cold waters for a 
part of the way may take place on the surface, and until 
the Polar flow’ dips down and becomes submarine. At 
any rate, Professor Bache reports that his assistants on 
the Coast Survey have found water at the bottom of the 
Gulf Stream, in latitude 25° 30’ N., as low in tempera- 
ture, as 35°. Now, if water flowing out of the Polar 
basin at the temperature of 28° may, by passing along 
the secret paths of the sea, reach the Gulf of Mexico in 
summer at a temperature of only 3° above the freezing 
point, why may not water, leaving the torrid zone at a 
temperature of 85°, and travelling by the same hidden 
ways, reach the frigid zone at the temperature of 36°? 

At the very time that the doctor was gazing with 
longing eyes upon these strange, green waters, there is 
known to have been a powerful drift setting out from 
another part of this Polar sea, and carrying with it from 


1g 14. 


CHAPTER 
Vill. 


§ 486 


Its tem- 
perature. 


Warm wa- 
ter within 
the Arctic 
circle need 
not excite 
surprise. 


Professor 
Bache. 


§ 487 


Drift set- 
ting out 
from Arec- 
tic Sea. 


206 THE PHYSICAL GEOGRAPHY OF THE SEA. 


cuarrer its mooring the English exploring ship Resolute, which 
ee Captain Kellett had abandoned fast bound in the ice 
E tects of several winters before. This drift carried a field of ice, 
that covered an area not less than 300,000 square miles, 
through a distance of a thousand miles to the south. The 
drift of this ship was a repetition of De Haven’s celebrated 
drift ;* for in each case the ice in which the vessel was 
fastened floated out and carried the vessel along with it: 
by which I mean to be understood as wishing to convey 
the idea that the vessel was not drifted through a line or 
an opening in the ice, but, remaining fast in the ice, she 

was carried along with the whole icy field or waste. 
§488 This field of ice averaged a thickness of not less than 
Dimen- seven feet ; at least that was the case with De Haven. 


sions and 


weight of A field of ice covering to the depth of seven feet an area 


ice drifted 
out of Po- of 300,000 square miles, would weigh not less than 


lar s 


throu 18,000,000,000 tons. This, then, is the quantity of 
Straits solid matter that is drifted out of the Polar Seas through 
one opening—Davis’ Straits alone—and during a part 
of the year only. The quantity of water which was re- 
quired to float and drive this solid matter out was pro- 
bably many times greater than this. A quantity of water 
equal in weight to these two masses had to goin. The 
basin to receive these inflowing waters—that is, the unex- 
plored basin about the North Pole—includes an area of a 
million and a half square miles; and as the outflowing 
ice and water are at the surface, the return current must 
Immense be Submarine. A part of the water that it bears pro- 


masnituc’ bably flows in beneath Dr. Kane’s barrier of ice.” 


between 
Temperate 
and Polar 
Kegions. 


These two currents, therefore, it may be perceived, 
keep in motion between the Temperate and Polar Regions 


* $ 530 2S 48 


THE OPEN SEA IN THE ARCTIC OCEAN. ZO7 


of the earth a volume of water, in comparison with which cxapres 
the mighty Mississippi, in its greatest floods, sinks down ie 
to a mere rill. 

On the borders of this ice-bound sea Dr. Kane found § 489 
subsistence for his party—another proof of the high tem- Pr Ksve. 


perature and comparative mildness of its climate. 


208 THE PHYSICAL GEOGRAPHY OF THE SEA. 


CHAPTER IX. 


THE SALTS OF THE SEA. 


Why is the Sea Salt? § 491.—An Hypothesis, 494.—The Adaptations of the Sea, 
498.—Components of Sea Water everywhere alike, 500.—Proportion of Solid 
Contents, 502.—The Influence of Wind upon the Circulation of the Sea, 508. 
—The Influence of Heat, 511.—The Influence of Evaporation, 517.—The In- 
fluence of Precipitation, 519.—Under Current from the Mediterranean and 
Red Sea due to the Salts of, 523.—Space that the Salts of the Sea would oceupy 
in a Solid State, 527.—De Haven’s Drift from the Arctic Ocean, 530.—An 
Under Current flowing into it, 534.—The Water Sky, 540.—Sea Shells, 545.— 
Their Agency in the System of Oceanic Circulation, 548.— They assist to regu- 
late Climate, 557.—Compensation in the Sea, 563.—Insects of the Sea, 565.— 
Geological Records concerning the Salts of the Sea, 568.—Light from the Bible, 
571.—Whence come the Salts of the Sea? 574.—Professor Chapman’s Experi- 
ments, 579. 


cuarteR IN order to comprehend aright the currents of the sea, and 
IX. . . . . : 
— to study with advantage its physical adaptations, it is 


Effect of necessary to understand the effects produced by the salts 
the salts of 
the sea 

on equili- 
brium of 


its waters. 14 1g restored by motion, and motion among fluid particles 


of the sea upon the equilibrium of its waters ; for where- 
ever equilibrium be destroyed, whether in the air or water, 


gives rise to currents, which, in turn, constitute circula- 
tion. 

This chapter is therefore added as a sort of supplement, 
which will assist us in elucidating what has been advanced 
concerning the currents of the sea. 

§ 491 The question is often asked, “ Why is the sea salt?” 
Cireula- J think it can be shown that the circulation of the ocean 


tion of 


ocean de- depends, in a great measure, upon the salts of sea-water ; 
pends on 


saltsof certainly its influences upon climate are greatly extended 
bea-water. 


by reason of its saltness. 
§ 492 Asa general rule, the sea is nearly of a uniform degree 


THE SALTS OF THE SEA. 209 


of saltness, and the constituents of sea water are as con- 
stant in their proportions as are the components of the 
atmosphere. It is true that we sometimes come across 
arms of the sea, or places in the ocean, where we find 
the water more salt or less salt than sea water is gene- 
rally ; but this circumstance is due to local causes of easy 
explanation. For instance: when we come to an arm of 
the sea, as the Red Sea; upon which it never rains, and 
from which the atmosphere is continually abstracting, by 
evaporation, fresh water from the salt, we may naturally 
expect to find a greater proportion of salt in the sea water 
that remains than we do near the mouth of some great 
river, as the Amazon, or in the regions of constant preci- 
pitation, or other parts where it rains more than it eva- 
porates. Therefore we do not find sea water from all 
parts of the ocean actually of the same degree of saltness ; 
yet we do find, as in the case of the Red Sea, sea water 
that is continually giving off to evaporation fresh water 
in large quantities ; nevertheless, for such water there is a 
degree, and a very moderate degree, of saltness which is a 
maximum ; and we moreover find that, though the con- 
stituents of sea water, like those of the atmosphere, are 
not for every place invariably the same as to their pro- 
portions, yet they are the same, or nearly the same, as to 
their character. 

When, therefore, we take into consideration the fact 
that, as a general rule, sea water is, with the exceptions 
above stated, everywhere and always the same, and that 
it can only be made so by being well shaken together, we 
find grounds on which to base the conjecture that the 
ocean has its system of circulation, which is probably as 


2 § 404, 
14 


CHAPTER 
IX. 


As a gene- 
ralrnlethe 
sea is uni- 
formly salt 


Excep- 
tions. 


§ 493 


Grounds 
for beliey 
ing that 
the ocean 
has a sys- 
tem of cir- 
culation. 


CHAPTER 
IX. 


$ 494 


Hypothe- 
sis neces- 
sary to 
progress 
in investi- 
gation. 


§ 495 


Hypothe- 
sis with re- 
gard to the 
silts of sea 
imparting 
dynamical 
force to its 
waters, 


210 THE PHYSICAL GEOGRAPHY OF THE SEA. 


complete, and not less wonderful, than is the circulation of 
blood through the human system. 

In order to investigate the currents of the sea, and to 
catch a glimpse of the laws by which the circulation of 
its waters is governed, hypothesis, in the present meagre 
state of absolute knowledge with regard to the subject, 
seems to be as necessary to progress as is a corner-stone 
to a building. ‘To make progress with such investiga- 
tions, we want something to build upon. In the absence 
of facts, we are sometimes permitted to suppose them: 
only, in supposing them, we should take not only the 
possible, but the probable; and in making the selection 
of the various hypotheses which are suggested, we are 
bound to prefer that one by which the greatest number 
of phenomena can be reconciled. When we have found, 
tried, and offered such an one, we are entitled to claim 
for it a respectful consideration at least, until we discover 
it leading us into some palpable absurdity, or until some 
other hypothesis be suggested which will account equally 
as well, but for a greater number of phenomena. ‘Then, 
as honest searchers after truth, we should be ready to give 
up the former, adopt the latter, and hold it until some 
other better than either of the two be offered. 

With this understanding, I venture to offer an hypo- 
thesis with regard to the agency of the salts or solid 
matter of the sea in imparting dynamical force to the 
waters of the ocean, and to suggest that one of the pur- 
poses which, in tne grand design, it was probably intended 
to accomplish by having the sea salt, and not fresh, was 
to impart to its waters the forces and powers necessary to 
make their circulation complete. 


THE SALTS OF THE SEA. ila 


In the first place, we do but conjecture when we say caaprra 


IX. 
that there is a set of currents in the sea by which its 

496 
waters are conveyed from place to place with regularity, Nee ie 


certainty, and order. But this conjecture appears to be °° 


rents, hav- 


founded on reason; for if we take a sample of water ims rese- 


which shall fairly represent, in the proportion of its con- ai. 
stituents, the average water of the Pacific Ocean, and 
nnalyze it, and if we do the same by a similar sample 
from the Atlantic, we shall find the analysis of the one 
to resemble that of the other as closely as though the two 
samples had been taken from the same bottle after having 
been well shaken. How, then, shall we account for this, 
unless upon the supposition that sea water from one part 
of the world is, in the process of time, brought into con- 
tact and mixed up with sea water from all other parts of 
the world? Agents, therefore, it would seem, are at 
work, which shake up the waters of the sea as though Waters in 


they were in a bottle, and which, in the course of time, tiesen 
mingle those that are in one part of the ocean with those gether. 
that are in another as thoroughly and completely as it is 
possible for man to do in a vessel of his own construction. 

This fact, as to uniformity of components, appears to § 497 
eal’ for the hypothesis that sea water, which to-day is in 
one part of the ocean, will, in the process of time, be 
found in another part the most remote. It must, there- seawater 
fore, be carried about by currents; and as these currents ee 
have their offices to perform in the terrestrial economy, ae 
they probably do not flow by chance, but in obedience to 
physical laws; they no doubt, therefore, maintain the 
order and preserve the harmony which characterize every 


department of God’s handiwork, upon the threshold of 


22 THE PHYSICAL GEOGRAPHY OF THE SEA. 


cnapter Which man has as yet been permitted to stand, to observe, 
4 eehe comprehend. 
$498 Nay, having reached this threshold, and taken a sur- 
The sea yey of the surrounding ocean, we are ready to assert, with 


has a sys- 


bemiof on all the confidence of knowledge, that the sea has a system 
of circulation for its waters. We rest this assertion upon 
our faith in the physical adaptations with which the sea 
is invested. Take, for example, the coral islands, reefs, 
beds, and atolls, with which the Pacific Ocean is studded 
and garnished. They were built up of materials which 
a certain kind of insect quarried from the sea water. The 
currents of the sea ministered to this little insect—they 
were its hod carriers. When fresh supplies of solid 
coral matter were wanted for the coral rock upon which the 
me foundations of the Polynesian Islands were laid, these 
hod carriers brought them in unfailing streams of sea 
water, loaded with food and building materials for the 
coralline. The obedient currents thread the widest and 
the deepest seas. They never fail to come at the right 
time, nor refuse to go; for, unless the currents of the sea 
were employed to carry off from this insect the waters 
that have been emptied by it of their lime, and to bring 
to it others charged with more, it is evident the litle 
creature would have perished for want of food long before 
Effects of its task was half completed. But for currents, it would 
Bigeye: have been impaled in a nook of the very drop of water 
ve in which it was spawned ; for it would soon have secreted 
the lime contained in this drop of water, and then, with- 
out the ministering aid of currents to bring it more, it 
would have perished for the want of food for itself and 


materials for its edifice: and thus, but for the benign 


THE SALTS OF THE SEA. iis 


currents which took this exhausted water away, there we 
perceive this emptied drop would have remained, not only 
us the grave of the little architect, but as a monument in 
attestation of the shocking monstrosity that there had 
been a failure in the sublime system of terrestrial adap- 
tations—that the sea had not been adapted by its Creator 
to the well-being of all its inhabitants. Now we do 
know that its adaptations are suited to all the wants of 
every one of its inhabitants—to the wants of the coral 
insect as well as tu those of the whale. Hence we say 
we know that the sea has its system of circulation, for it 
transports materials for the coral rock from one part of 
the world to another ; its currents receive them from the 
rivers, and hand them over to the little mason for the 
structure of the most stupendous works of solid masonry 
that man has ever seen—the coral islands of the sea. 
Thus, by a process of reasoning which is perfectly phi- 
losophical, we are irresistibly led to conjecture that there 
are regular and certain, if not appointed channels, through 
which the water travels from one part of the ocean to 
another ; and that those channels belong to an arrange- 
ment which may make, and, for aught we know to the 
contrary, which does make, the system of oceanic circula- 
tion as complete, as perfect, and as harmonious, as is that 
of the atmosphere or the blood. Every drop of water in 
the sea is as obedient to law and order as are the mem- 
bers of the heavenly host in the remotest regions of space. 
For when the morning stars sang together in the almighty 
anthem, “the waves, also, lifted up their voice ;” and 
doubtless, therefore, the harmony in the depths of the 
ocean is in tune with that which comes from the spheres 


» 


CHAPTER 
Ix. 


§ 499 


Trresisti- 
ble con- 
clusion. 


CHAPTER 
IX. 


Author's 
opinion. 


$ 500 
[llustra- 


tion of the 
Red Sea. 


§ 501 
Tilustra- 
tion of the 
Mediter- 
ranean. 


ae THE PHYSICAL GEOGRAPHY OF THE SEA. 


above. We cannot doubt it: for, were it not so, were 
there no channels of circulation from one ocean to another, 
and if, accordingly, the waters of the Atlantic were 
confined to the Atlantic, or if the waters of the arms and 
seas of the Atlantic were confined to those arms and 
seas, and had no channels of circulation by which they 
could pass out into the ocean, and traverse different 
latitudes and climates—if this were so, then the machinery 
of the ocean would be as incomplete as that of a watch 
without a balance-wheel; for the waters of these arms 
and seas would, as to their constituents, become, in the 
process of time, very different from the sea waters in 
other parts of the world, and their inhabitants would 
perish for the want of brine of the right strength, or of 
water of the right temperature. 

For instance, take the Red Sea and the Mediterranean 
by way of illustration. Upon the Red Sea there is no 
precipitation ; it is a rainless region; not a river runs 
down to it, not a brook empties into it: therefore there 
is no process by which the salts and washings of the 
earth, which are taken up and held in solution by rain 
or river water, can be brought down into the Red Sea. 
Its salts come from the ocean, and the air takes up from 
it, in the process of evaporation, fresh water, leaving 
behind, for the currents to carry away, the solid matter 
which, as sea water, it held in solution. 

On the other hand, numerous rivers discharge them- 
selves into the Mediterranean, some of which are filtered 
through soils and among minerals which yield one kind 
of salt or soluble matter; another river runs through a 
limestone or voleanic region of country, and brings down 


THE SALTS OF THE SEA. Des 


in solution sod matter—it may be common salt, sulphate 
or carbonate of lime, magnesia, soda, potash, or iron— 
either or all may be in its waters. Still, the constituents 
of sea water from the Mediterranean, and of sea water 
from the Red Sea, are quite the same. But the waters 
of the Dead Sea have no connection with those of the 
ocean ; they are cut off from its channels of circulation, 
and are, therefore, quite different, as to their components, 
from any arm, frith, or gulf of the broad ocean. Its 
inhabitants are also different from those of the high 
seas. 

“The solid constituents of sea water amount to about 
three and a half per cent. of its weight, or nearly half an 
ounce to the pound. Its saltness may be considered as a 
necessary result of the present order of things. Rivers 
which are constantly flowing into the ocean contain salts, 
varying from ten to fifty, and even one hundred grains 
per gallon. They are chiefly common salt, sulphate and 
carbonate of lime, magnesia,* soda, potash, and iron; and 
these are found to constitute the distinguishing character- 
istics of sea water. The water which evaporates from 
the sea is nearly pure, containing but very minute traces 
of salts, Falling as rain upon the land, it washes the 
soil, percolates through the rocky layers, and becomes 
charged with saline substances, which are borne sea-ward 
by the returning currents. The ocean, therefore, is the 
great depository of everything that water can dissolve 
and carry down from the surface of the continents; and, 
as there is no channel for their escape, they, of course, 

* It is the chloride of magnesium which gives that damp, sticky feelirg to the 
clothes of sailors that are washed or wetted with salt water. 


» 


CHAPTER 
Ix. 


§ 502 
Solid con- 


stituents of 
sea-water, 


Water eva- 
porated 
from sea 
nearly 
pure. 


CHAPTER 
Ix. 


RAs 

§ 503 
Fowner’s 
remarks 

on the sea 


§ 504 


Constitu- 
ents of at- 
mosphere 
the same 
every- 
where. 


§ 505 


Agents 
concerned 
in giving 
circulation 
to the at- 
mosphere. 


216 THE PHYSICAL GEOGRAPHY OF THE SEA 


consequently accumulate.”* They would constantly ac- 
curoulate, as this very shrewd author remarks, were it 
not for the shells and insects of the sea and other agents 
mentioned. 

“The case of the sea,” says Fowner, “is but a magni- 
fied representation of what occurs in every lake into 
which rivers flow, but from which there is no outlet 
except by evaporation. Such a lake is invariably a salt 
lake. It is impossible that it can be otherwise; and it 
is curious to observe that this condition disappears when 
an artificial outlet is produced for the waters.” 

How, therefore, shall we account for this sameness of 
compound, this structure of coral, this stability as to 
animal life in the sea, but upon the supposition of a 
general system of circulation in the ocean, by which, in 
process of time, water from one part is conveyed to another 
part the most remote, and by which a general interchange 
and commingling of the waters take place? In like 
manner, the constituents of the atmosphere, whether it 
be analyzed at the equator or the poles, are the same. 
By cutting off and shutting up from the general channels 
of circulation any portion of sea water, as in the Dead 
Sea; or of atmospheric air, as in mines or wells; we can 
easily fill either with gases or other matter that shall 
very much affect its character, or alter the proportion of 
its ingredients, and affect the health of its inhabitants : 
but in the open sea or open air, no. 

The principal agents that are supposed to be concerned 
in giving circulation to the atmosphere, and in preserving 
the ratio among its components, are, light, heat, electricity, 


* Youman’s Chemistry. 
1 g 498, 


THE SALTS OF THE SEA. 277 


and magnetism. But with regard to the sea, it is not 
known what office is performed by electricity and magnet- 
ism, In giving dynamical force to its waters in their 
system of circulation. The chief motive power from which 
marine currents derive their velocity has been ascribed 
to heat ; but a close study of the agents concerned has 
suggested that an important, nay, a powerful and active 
agency, in the system of oceanic circulation, is derived 
from the salts of the sea water, through the instrumentality 
of the winds, of marine plants and animals. These give 
the ocean great dynamical force. 

Let us, for the sake of illustrating and explaining this 
force, suppose the sea in all its parts—in its depths and 
at the surface, at the equator and about the poles—to be 
of one uniform temperature, and to be all of fresh water ; 
and, moreover, that there be neither wind to disturb its 
surface, nor tides nor rains to raise the level in this part, 
or to depress it in that. In this case, there would be 
nothing of heat to disturb its equilibrium, and there 
would be no motive power’ to beget currents, or to set 
the water in motion by reason of the difference of level 
or of specific gravity due to water at different densities 
and temperatures. 

Now let us suppose the winds, for the first time since 
the creation, to commence to blow upon this quiescent sea, 
and to ruffle its surface ; they, by their force, would create 
partial surface currents, and thus agitating the waters, as 
they do, but only for a little way below the surface, 
would give rise to a feeble and partial aqueous circulation 
in the supposed sea of fresh water. 

This, then, is one of the sources whence power is given 


1 ¢ 490, 


CHAPTER 
IX. 


Salts, 
through 
instru- 
mentality 
of winds, 
marine 
animals, 
and plants, 
give dyna- 
mical fores 
to the 
ocean. 


§ 506 


Tllustra- 
tion. 


§ 507 


Winds. 


$ 508 


CHAPTPR 
Ix. 


§ 509 


Evapora- 
tion and 
precipita- 
tion—heat 
and cold. 


$510 


Eyapora- 
tion. 


§ 511 


Heat and 
cold. 


218 THE PHYSICAL GEOGRAPHY OF THE SEA. 


to the system of oceanic circulation; but though a feeble 
one, it is one which exists in reality, and, therefore, need 
not be regarded as hypothetical. 

Let us next call in evaporation and _ precipitation, 
with heat and cold—more powerful agents. Suppose 
the evaporation to commence from this imaginary fresh 
water ocean, and to go on as it does from the seas as 
they are. In those regions, as in the trade-wind 
regions, where evaporation is in excess of precipitation, 
the general level of this supposed sea would be altered, 
and, immediately, as much water as is carried off by 
evaporation would commence to flow in from north and 
south toward the trade-wind or evaporating region, to 
restore the level. 

On the other hand, the winds have taken this vapour, 
borne it off to the extra-tropical regions, and precipitated 
it, we will suppose, where precipitation is in excess of 
evaporation. Here is another alteration of sea level 
by elevation instead of by depression; and hence we 
have the motive power for a surface-current from each 
pole toward the equator, the object of which is only 
to supply the demand for evaporation in the trade-wind 
regions—demand for evaporation being taken here to 
mean the difference between evaporation and _ precipi- 
tation for any part of the sea. 

Now, imagine this sea of uniform temperature’ to be 
suddenly stricken with the invisible wand of heat and 
cold, and its waters brought to the various temperatures 
at which they at this instant are standing. This change 
of temperature would make a change of specific gravity 
in the waters, which would destroy the equilibrium of 


2 § 178. 25 506. 


THE SALTS OF THE SEA. 219 


the whole ocean, upon which a set of currents would cuaprrr 
immediately commence to flow, namely, a current of cold cae 
and heavy water to the warm, and a current of warm 
and lighter to the cold. 
The motive power of these would be difference of spe- Motive 
cific gravity due to difference of temperature in fresh water. tiga 
We have now traced’ the effect of two agents, which, § 512 
in a sea of fresh water, would tend to create currents, 
and to beget a system of aqueous circulation; but a set 
of currents and a system of circulation which, it is 
readily perceived, would be quite feeble in comparison 
with those which we find in the salt sea. One of these Employ- 


ment of 
agents would be employed’in restoring, by means of one the two 


or more Polar currents, the water that is taken from one ects to 
part of the ocean by evaporation, and deposited in an- rena tt 
other by precipitation. The other agent would be San 
employed in restoring, by the force’s due difference of 
specific gravity, the equilibrium, which has been dis- 
turbed by heating, and of course expanding, the waters 

of the torrid zone on the one hand, and by cooling, and 
consequently contracting, those of the frigid zone on the 

other. This agency would, if it were not modified by 
others, find expression in a system of currents and coun- 

ter currents, or rather in a set of surface currents, of 

warm and light water, from the equator toward the 
poles; and in another set of under currents of cooler, 

dense, and heavy water, from the poles toward the 
equator. 

Such, keeping out of view the influence of the winds, § 513 

which we may suppose would be the same whether the 


sea were salt or fresh, would be the system of oceanic 


1 § 507 and § 511. 2 509. 8 § 511. 


220 THE PHYSICAL GEOGRAPHY OF THE SEA. 


cnaptzr circulation were the sea all of fresh water. But fresh 

“* water, in cooling, begins to expand near the temperature 

of 40°, and expands more and more till it reaches the 

cere freezing point, and ceases to be fluid. This law of expan- 
ache 


culation of Sion by cooling would impart a peculiar feature to the 
a fresh- 2 ° : 

water System of oceanic circulation were the waters all fresh, 
ocean . . . . . 
whichean- Which it is not necessary to notice further than to say it 


not exist 


In seas of cannot exist in seas of salt water, for salt water’ contracts 
satwate os its temperature is lowered to its freezing point. 
Hence, in consequence of its salts, changes of tempera- 
ture derive increased power to disturb the equilibrium 
of the ocean. 
g§514 (If this train of reasoning be good, we may infer that, 
Inference. jn a system of oceanic circulation, the dynamical force to 
be derived from difference of temperature, where the 
waters are all fresh, would be quite feeble; and that, 
were the sea not salt, we should probably have no such 
current in it as the Gulf Stream. 
$515 So far we have been reasoning hypothetically, to show 
what would be the chief agents, exclusive of the winds, 
in disturbing the equilibrium of the ocean, were its 
waters fresh, and not salt. And whatever disturbs equi- 
librium there may be regarded as the primum mobile in 
any system of marine currents. 
¢51¢6 Let us now proceed another step in the process of 
Another e=piaiane and illustrating we efied - the salts o the 
tion. sea in the system of oceanic circulation. To this end, 
. let us suppose the imaginary ocean of fresh water sud- 
denly to become that which we have, namely, an ocean 
of salt water, which contracts as its temperature is low- 
ered till it reaches 28° or thereabout. 


§ 31. 2 $ 513. 


© 


THE SALTS OF THE SBA. BOA | 


Let evaporation now commence in the trade-wind 
region, as it was supposed to do’ in the case of the fresh 


water seas, and as it actually goes on in nature—and 


what takes place? Why, a lowering of the sea-level, 
as before. But as the vapour of salt water is fresh, or 
nearly so, fresh water only is taken up from the ocean ; 
that which remains behind is therefore more salt. Thus, 
while the leve! is lowered in the salt sea, the equilibrium 
is destroyed because of the saltness of the water; for the 
water that remains after the evaporation takes place is, 
on account of the solid matter held in solution, specifi- 
eally heavier than it was before any portion of it was 
converted into vapour. 


The vapour is taken from the surface water; the sur- 


face water thereby becomes more salt, and, under certain 
conditions, heavier. When it becomes heavier, it sinks; 
and hence we have, due to the salts of the sea, a vertical 
circulation, namely, a descent of heavier—because salter 
and cooler—water from the surface, and an ascent of 
water that is lighter—because it is not so salt—from the 
depths below. 

This vapour, then, which is taken up from the evapo- 
rating regions, is carried by the winds through their 
channels of circulation, and poured back into the ocean 
where the regions of precipitation are ; and by the regions 
of precipitation I mean those parts of the ocean, as in 
the Polar basins, where the ocean receives more fresh 
water, in the shape of rain, snow, &c., than it returns to 
the atmosphere in the shape of vapour. 

In the precipitating regions, therefore, the level is de- 
stroyed, as before explained, by elevation; and in the 


1 § 509, 2 $179, 


CHAPTER 
Ix. 


mm 
or 
— 


7 


Evapova- 
tion of salt 
water. 


§ 519 
Vapour 
carried 
away by 
winds, and 
poured 
back into 
other parts 
of the sea. 


$ 520 


Cause of 
surtace 
currents 


CHAPTER 
Ix. 


§ 521 


The fresh 
water eva- 
porated 
supposed 
(for illus- 
tration) to 
be deposit- 
edin north 
Polar 
basin. 


§ 522 
Effect of 


the fresh 
water, 


§ 523 


Currents 
of Medi- 

terranean 
aud Red 

REA, 


299 THE PHYSICAL GEOGRAPHY OF THE SEA. 


evaporating regions, by depression; which, as already 
stated; gives rise to a system of surface currents, moved 
by gravity alone, from the poles toward the equator. 

But we are now considering the effects of evaporation 
and precipitation in giving impulse to the circulation of 
the ocean where its waters are salt. The fresh water 
that has been taken from the evaporating regions is de- 
posited upon those of precipitation ; which, for illustration 
merely, we will locate in the north Polar basin. Among 
the sources of supply of fresh water for this basin, we 
must include not only the precipitation which takes place 
over the basin itself, but also the amount of fresh water 
discharged into it by the rivers of the great hydrographi- 
cal basins of Arctic Europe, Asia, and America. 

This fresh water, being emptied into the Polar Sea and 
agitated by the winds, becomes mixed with the salt; but 
as the agitation of the sea by the winds is supposed to 
extend to no great depth; it is only the upper layer of 
salt water, and that to a moderate depth, which becomes 
mixed with the fresh. The specific gravity of this upper 
layer, therefore, is diminished just as much as the specific 
gravity of the sea water in the evaporating regions was 
increased, And thus we have a surface current of saltish 
water from the poles toward the equator, and an under 
current of water salter and heavier from the equator to 
the poles. This under current supplies, in a great measure, 
the salt which the upper current, freighted with fresh 
water from the clouds and rivers, carries back. 

Thus it is to the salts of the sea that we owe that 
feature in the system of oceanic circulation which causes 
an under current to flow from the Mediterranean into 


THE SALTS OF THE SEA, 225 


the Atlantic,’ and another? from the Red Sea into the 
Indian Ocean. And it is evident, since neither of these 
seas is filling up, that just as much, or nearly just as 
much salt as the under current brings out, just so much 
the upper currents carry in. 

We now begin to perceive what a powerful impulse is 
derived from the salts of the sea in giving effective and 
active circulation to its waters. 

Hence we infer that the currents of the sea, by reason 
of its saltness, attain their maximum of volume and velo- 
city. Hence, too, we infer that the transportation of 
warm water from the equator toward the frozen regions 
of the poles, and of cold water from the frigid toward 
the torrid zone, is facilitated ; and consequently here, in 
the saltness of the sea, have we not an agent by which 
climates are mitigated—by which they are softened and 
rendered much more salubrious than it would be possible 
for them to be were the waters of the ocean deprived of 
their property of saltness ? 

This property of saltness imparts to the waters of the 
ocean another peculiarity, by which the sea is stili better 
adapted for the regulation of climates, and it is this: By 
evaporating fresh water from the salt in the tropics, the 
surface water becomes heavier than the average of sea 
water.’ This heavy water is also warm water; it sinks, 
and being a good retainer, but a bad conductor of heat, 
this warm water is employed in transporting through 
under currents heat for the mitigation of climates in far- 
distant regions. Now this also is a property which a 
sea of fresh water could not have. Let the winds take 
up their vapour from a sheet of fresh water, and that at 


1 § 495, 2 $413. 3 § 181, 


CHAPTER 
1X, 


§ 524 


§ 525 


Tnferences, 


§ 526 
Another 
peculiarity 
imparted 
to the 
waters of 
the sea by 
their salts 


no 


24 THE PHYSICAL GEOGRAPHY OF THE SEA. 


carrer the bottom is not disturbed, for there is no change in the 
Ix. 


specific gravity of that at the surface, by which that at 


Specific 


gravity. the bottom may be brought to the top; but let evapora- 
tion go on, though never so gently, from salt water, and 
the specific gravity of that at the top will soon be so 
changed as to bring that from the very lowest depths of 
the sea to the top. 

§ 527 If all the salts of the sea were precipitated and spread 
eusuaty out equally over the northern half of this continent, it 
the sea would, it has been computed, cover th> ground one mile 

deep. What force could move such a mass of matter on 
the dry land? Yet the machinery of the ocean, of which 
it forms a part, is so wisely, marvellously, and wonder- 
fully compensated, that the most gentle breeze that plays 
on its bosom, the tiniest insect that secretes solid matter 
for its sea-shell, is capable of putting it instantly in mo- 
Remarks tion, Still, when solidified and placed in a heap, all the 


on the in- 


ee mechanical contrivances of man, aided by the tremendous 

man. forces of all the steam and water power of the world, 

could not move even so much as an inch in centuries 

of time this matter, which the sunbeam, the zephyr, 

and the infusorial insect, keep in perpetual motion and 
activity. 

§ 528 If these inferences as to the influence of the salts upon 

see the currents of the sea be correct, the same cause which 

produces an under current from the Mediterranean and 

an under current from the Red Sea into the ocean, should 

produce an under current from the ocean into the north 

Polar basin. In each case, the hypothesis with regard 

to the part performed by the salt, in giving vigour to the 


system of oceanic circulation, requires that, counter to the 


Ls) 


THE SALTS OF THE SEA. 225 


surface current of water with less salt, there should be 
an under current of water with more salt in it. 


That such is the case with regard both to the Mediter- § ; 


ranean and the Red Sea has been amply shown in other 
parts of this work, and abundantly proved by other ob- 


servers. 


That there is a constant current setting out of the g; 


Arctie Ocean through Davis’ and other straits thereabout, 
which connect it with the Atlantic Ocean, is generally 
admitted. Lieutenant De Haven, United States navy, 
when in command of the American expedition in search 
of Sir John Franklin, was frozen up with his vessels in 
mid-channel near Wellington Straits ; and during the nine 
months that he was so frozen, his vessels, like H. B. M. 
ship Resolute,” each holding its place in the ice, were 
drifted with it bodily for more than a thousand miles 
toward the south. 


The ice in which they were bound was of sea water, § 


and the currents by which they were drifted were of sea 
water ; only, it may be supposed, the latter were not 
quite so salt as the sea water generally is. The same 
phenomenon is repeated in the Baltic, where’ an under 
current of salt water runs in, and an upper current of 
brackish water‘*runs out. 

Then, since there is salt always flowing out of the 
Polar basin, we infer that there must be salt always flow- 
ing into it, else it would either become fresh, or the whole 
Atlantic Ocean would be finally filled up with salt. 

It might be supposed, were there no evidence to the 
contrary, that this salt was supplied to the Polar Seas 
from the Atlantic around North Cape, and from the 


1 § 523. 2 § 487. + § 423. * § 37. 


1d 


CHAPTER 
IX. 


A constant 
ewrent 
Setting out 
of the 
Arctic 
Ocean. 


Currents 
in the 
Baltic. 


$ 532 


Inference 


CHAPTER 
Ix. 


§ 534 


Proof af- 
forded by 
Arctic 
voyagers. 


$9539 


Midship- 
man 
Griffin. 


Iceberg 
drifting 
against the 
current. 


§ 536 


226 THE PHYSICAT. GEOGRAPHY OF THE SEA. 


Pacific through Behring’s Straits, and through no other 
channels. 

But, fortunately, Arctic voyagers, who have cruised in 
the direction of Davis’ Straits, have afforded us, by their 
observations, proof positive as to the fact of this other 
source for supplying the Polar Seas with salt. They tell 
us of an under current setting from the Atlantic toward 
the Polar basin. They describe huge icebergs, with tops 
high up in the air, and of course the bases of which ex- 
tend far down into the depths of the ocean, ripping and 
tearing their way with terrific force and awful violence 
through the surface ice, or against a surface current, on 
their way into the Polar basin. 

Passed Midshipman S. P. Griffin, who commanded the 
brig Rescue in the American searching expedition after 
Sir John Franklin, informs me that, on one occasion the 
two vessels were endeavouring, when in Baffin’s Bay, to 
warp up to the northward against a strong surface cur- 
rent, which of course was setting to the south; and that 
while so engaged, an iceberg, with its top many feet above 
the water, came “ drifting up” from the south, and passed 
by them “like a shot.” Although they were stemming 
a surface current against both the berg and themselves, 
such was the force and velocity of the under current, that 
it carried the berg to the northward faster than the crew 
could warp the vessel against a surface but counter current. 

Captain Duncan, master of the English whale-ship 
Dundee, says, at page 76 of his interesting little nar- 
rative :—* 

* Arctic Regions; Voyage to Davis’ Straits, by Dorea Duncan, Master of the 


Ship Dundee, 1826, 1827. 
1 § 478. 


THE SALTS OF THE SEA. paar 


“ Dec. 18th [1826]. It was awful to behold the 
immense icebergs working their way to the north-east 
from us, and not one drop of water to be seen; they were 
working themselves right through the middle of the ice.” 

And again, at page 92, &c. :— 

“ Feb. 23d. Latitude 68° 37’ north, longitude about 
63° west. 

“The dreadful apprehensions that assailed us yester- 
day, by the near approach of the iceberg, were this day 
most awfully verified. About three pM. the iceberg 
came in contact with our floe, and in less than one minute 
it broke the ice. We were frozen in quite close to the 
shore; the floe was shivered to pieces for several miles, 
causing an explosion like an earthquake, or one hundred 
pieces of heavy ordnance fired at the same moment. The 
iceberg, with awful but majestic grandeur (in height and 
dimensions resembling a vast mountain) came almost up 
to our stern, and every one expected it would have run 
over the ship..... j 

“The iceberg, as before observed, came up very near 
to the stern of our ship; the intermediate space between 
the berg and the vessel was filled with heavy masses of 
ice, which, though they had been previously broken by 
the immense weight of the berg, were again formed into 
a compact body by its pressure. The berg was drifting 
at the rate of about four knots, and by its force on the 
mass of ice, was pushing the ship before it, as it appeared, 
to inevitable destruction. 

“Feb. 24th. The iceberg still in sight, but driving 
away fast to the north-east. 

“Feb 25th. The iceberg that so lately threatened our 


CHAPTEK2 
Ix. 
Captain 
Duncan's 
remarks 
on ice- 
bergs. 


Continued 


Continued 


CHAPTER 


3 537 
Author's 
opinion. 


e = 

$ 538 
Tempera- 
ture of 
under cur- 
rent 


Tempera- 
ture of sur- 
face water. 


Tempera- 
ture of 
Arctic 
Ocean. 


228 THE PHYSICAL GEOGRAPHY OF THE SEA. 


destruction had driven completely out of sight to the 
north-east from us.” 

Now, then, whence, unless from the difference of spe- 
cific gravity due sea water of different degrees of saltness 
and temperature, can we derive a motive power with 
force sufficient to give such tremendous masses of ice such 
a velocity ? 

What is the temperature of this under current? Be 
that what it may, it is probably above the freezing point 
of sea water. Suppose it to be at 32° Break through 
the ice in the northern seas, and the temperature of the 
surface water is always 28°; at least Lieutenant De 
Haven so found it in his long imprisonment, and it may — 
be supposed that, as it was with him, so it generally is. 
Assuming, then, the water of the surface current which 
runs out with the ice to be all at 28°, we observe that it 
is not unreasonable to suppose that the water of the under 
current, inasmuch as it comes from the south, and there- 
fore from warmer latitudes, is probably not so cold; and 
if it be not so cold, its temperature, before it comes out 
again, must be reduced to 28°, or whatever be the aver- 
age temperature of the outer but surface current. Dr. 
Kane found the temperature of the open sea in the Arctic 
Ocean’ as high as 36°. Can water flow in the depths 
below from the mild climate of the temperate zones to 
the severe climate of the frigid zones without falling below 
36°? To what, in the depths of the sea, can a warm 
current of large volume impart its heat? 

Moreover, if it be true, as some philosophers have sug- 
gested, that there is in the depths of the ocean a floor or 
plane from the equator to the poles along which the water 


1 § 486, 


THE SALTS OF THE SEA. 229 


is of the same temperature all the way, then the question 
may be asked, Should we not have in the depths of the 
ocean a sort of isothermal floor, as it were, on the upper 
side of which all the changes of temperature are due to 
agents acting from above, and on the lower side of which, 
the changes, if any, are due to agents acting from below? 

This under Polar current water, then, as it rises to the 
top, and is brought to the surface by the agitation of the 
sea in the Arctic Regions, gives out its surplus heat and 
warms the atmosphere there till the temperature of this 
warm under current water is lowered to the requisite 
degree for going out on the surface. Hence the water- 
sky of those regions. 

And the heat that it loses in falling from its normal 
temperature, be that what it may, till it reaches the tem- 
perature of 28°, is so much caloric set free in the Polar 
Regions, to temper the air and mitigate the climate there. 
Now, is not this one of those modifications of climate 
which may be fairly traced back to the effect of the salt- 
ness of the sea in giving energy to its circulation ? 

Moreover, if there be a deep sea in the Polar basin, 
which serves as a receptacle for the waters brought into 
it by this under current, which, because it comes from 
toward the equatorial regions, comes from a milder climate, 
and is therefore warmer, we can easily imagine why there 
might be an open sea in the Polar Regions; why Lieu- 
tenant De Haven, in his instructions, was directed to look 
for it; and why both he and Captain Penny, of one of the 
English searching vessels, and afterward Dr. Kane, found 
it there. 

And in accounting for this polynia, we see that its 


2 § 482. 


CHAPTER 
IX. 


Isothermal 
floorin the 
ocean. 


§ 540 


Cause of 
the water- 
sky of 
Polar 
regions. 


§ 541 


Cause of 
modifica- 
tion of 
Polar 
climate. 


§ 542 
Easy to 
imagine 
why there 
might be 
an open 
sea in 
Polar 
regions. 


§ 543 


"HAPTER 
IX. 


Effects 
produced 
by the 
salts of sea 
on mobili- 
ty and cir- 
culation of 
its waters 


§ 544 
Conclud- 


ing re- 
marks. 


§ 545 
Sea shells. 
Lime em- 
ployed in 
their for- 
mation. 


Office of 
the in- 
habitants 
of the 
deep. 


§$ 546 


230 THE PHYSICAL GEOGRAPHY OF THE SEA. 


existence is not only consistent with the hypothesis with 
which we set out, touching a perfect system of oceanic 
circulation, but that it may be ascribed, in a great degree 
at least, if not wholly, to the effect produced by the 
salts of the sea upon the mobility and circulation of its 
waters. 

Here, then, is an office which the sea performs in the 
economy of the universe by virtue of its saltness, and 
which it could not perform were its waters altogether fresh. 
And thus philosophers have a clew placed in their hands 
which will probably guide them to one of the many hid- 
den reasons that are embraced in the true answer to the 
question, “ Why is the sea salt?” 

SeA SHELLS.—We find in sea water other matter besides 
common salt. Lime is dissolved by the rains and the 
rivers, and emptied in vast quantities into the ocean. Out 
of it, coral islands and coral reefs of great extent, marl- 
beds, shell-banks, and infusorial deposits of enormous mag- 
nitude, have been constructed by the inhabitants of the 
deep. These creatures are endowed with the power of 
secreting, apparently for their own purposes only, solid 
matter, which the waters of the sea hold in solution. But 
this power was given to them that they also might fulfil 
the part assigned them in the economy of the universe. 
For to them, probably, has been allotted the important 
office of assisting in giving circulation to the ocean, of 
helping to regulate the climates of the earth, and of pre- 
serving the purity of the sea. 

The better to comprehend how such creatures may in- 
fluence currents and climates, let us suppose the ocean to 
be perfectly at rest; that throughout, it is in a state of 


THE SALTS OF THE SEA. 231 


complete equilibrium ; that, with the exception of those 
tenants of the deep which have the power of extracting 
from it the solid matter held in solution, there is no agent 
in nature capable of disturbing that equilibrium; and 
that all these fish, &c., have suspended their secretions, in 
order that this state of a perfect aqueous equilibrium and 
repose throughout the sea might be attained. 

In this state of things—the waters of the sea being in 
perfect equilibrium—a single mollusc or coralline, we will 
suppose, commences his secretions, and abstracts from the 
sea water’ solid matter for his cell. In that act, this 
animal has destroyed the equilibrium of the whole ocean; 
for the specific gravity of that portion of water from 
which this solid matter has been abstracted is altered. 
Having lost a portion of its solid contents, it has become 
specifically lighter than it was before; it must, therefore, 
give place to the pressure which the heavier water exerts 
to push it aside and to occupy its place, and it must con- 
sequently travel about and mingle with the waters of the 
other parts of the ocean until its proportion of solid mat- 
ter is returned to it, and until it attains the exact degree 
of specific gravity due sea water generally. 

How much solid matter does the whole host of marine 
plants and animals abstract from sea water daily? Is it 
a thousand pounds, or a thousand millions of tons? No 
one can say. But, whatever be its weight, it is so much 
of the power of gravity applied to the dynamical forces 
of the ocean. And this power is derived from the salts 
of the sea, through the agency of sea shells and other 
marine animals, that of themselves scarcely possess the 
power of locomotion. Yet they have power to put the 


1 § 498, 


CHAPTER 
IX. 


Supposi- 
tion 


§ 547 
Effect of 
the opera- 
tions of a 
single 
coralline. 


§ 548 


Solid 
matter abe 
stracted 
from sea 
by marine 
animals. 


Zon THE PHYSICAL GEOGRAPHY OF THE SRA. 


cxapter Whole sea in motion, from the equator to the poles, and 
—~ from top to bottom. 
$549 Those powerful and strange equatorial currents’ which 
Provable navigators tell us they encounter in the Pacific Ocean, to 


cause of 


enroute in what are they due? Coming from sources unknown, 

they are lost in the midst of the ocean. They are due, 

no doubt, to some extent, to the effects of precipitation 

and evaporation, and the change of heat produced thereby. 

But we have yet to inquire how far they may be due to 

the derangement of equilibrium arising from the change 

of specific gravity caused by the secretions of the myriads 

of marine animals that are continually at work in those 

parts of the ocean. These abstract from sea water solid 

matter enough to build continents of. And also we have 

to inquire as to the extent to which equilibrium in the 

sew is disturbed by the salts which evaporation leaves 
behind. 

§550 #Thus, when we consider the salts of the sea in one 

Principles point of view, we see the winds and the marine animals 


vs operating upon the waters, and, in certain parts of the 
ocean, deriving from the solid contents of the same those 
very principles of antagonistic forces which hold the earth 
in its orbit, and preserve the harmonies of the universe. 
Soll In another point of view, we see the sea breeze and 
ayeenieal the sea shell, in performing their appointed offices, acting 
so as to give rise to a reciprocating motion in the waters; 
and thus they impart to the ocean dynamical forces also 
for its circulation. 
$552 The sea breeze plays upon the surface ; it converts only 
Thesea fresh water into vapour, and leaves the solid matter be- 


breeze. 


hind. The surface water thus becomes specifically heavier, 


1 $ 438. 


THE SALTS OF THE SEA. 233 


and sinks. On the other hand, the little marine architect 
below, as he works upon his coral edifice at the bottom, 
abstracts from the water there a portion of its solid con- 
tents; it therefore becomes specifically lighter, and up it 
goes, ascending to the top with increased velocity, to take 
the place of the descending column, which, by the action 
of the winds, has been sent down loaded with fresh food 
and materials for the busy little mason in the depths 
below. 

Seeing, then, that the inhabitants of the sea, with their 
powers of secretion, are competent to exercise at least 
some degree of influence in disturbing equilibrium, are 
not these creatures entitled to be regarded as agents 
which have their offices to perform in the system of 
oceanic circulation, and do not they belong to its physical 
geography? It is immaterial how great or how small 
that influence may be supposed to be; for, be it great or 
small, we may rest assured it is not a chance influence, 
but it is an influence exercised—if exercised at all—by 
design, and according to the commandment of Him whose 
“voice the winds and the sea obey.” Thus God speaks 
through sea shells to the ocean. 

It may therefore be supposed that the arrangements 
in the economy of nature are such as to require that the 
various kinds of marine animals, whose secretions are 
calculated to alter the specific gravity of sea water, to 
destroy its equilibrium, to beget currents in the ocean, 
and to control its circulation, should be distributed ac- 
cording to order. 

Upon this supposition—the like of which nature war- 
rants throughout her whole domain—we may conceive 


CHAPTER 
1X. 


Its effects 
and coun- 
ter effects. 


§ 552 
Position 
assigned 
to inhabit- 
ants of the 
Sea, 


God speaks 
to ocean 
through 


its shells. 


§ 553 


Marine 
animals 
distributed 
according 
to order. 


J 7) 
or 
Or 
ves 


CHAPTER 

LD.& 
Marine 
animals 
may im- 
press other 
features on 
fhe physi- 
eal rela- 
tions of the 
Mea. 


§ 555 
No coral 
islands if 
sea were 
not salt. 


§ 556 
Under 
current 
freighted 
with heat. 


234 THE PHYSICAL GEOGRAPHY OF THE SEA. 


how the marine animals of which we have been speaking 
may impress other features upon the physical relations of 
the sea, by assisting also to regulate climates and to adjust 
the temperature of certain latitudes. For instance, let us 
suppose the waters in a certain part of the torrid zone to 
be 90°, but, by reason of the fresh water which has been 
taken from them in a state of vapour, and consequently 
by reason of the proportionate increase of salts, these 
waters are heavier than waters that may be cooler, but 
not so salt." This being the case, the tendency would be 
for this warm, but salt and heavy water, to flow off as 
an under current towards the Polar or some other regions 
of lighter water. 

Now, if the sea were not salt, there would be no coral 
islands to beautify its landscape and give variety to its 
features ; sea shells and marine insects could not operate 
upon the specific gravity of its waters, nor give diversity 
to its climates ; neither could evaporation give dynamical 
force to its circulation, and its waters, ceasing to contract 
as their temperature falls below 39°, would give but little 
impulse to its currents, and thus its circulation would be 
torpid, and its bosom lack animation. 

This under current may be freighted with heat to 
temper some hyperborean region or to soften some extra- 
tropical climate, for we know that such is among the 
effects of marine currents. At starting, it might have 
been, if you please, so loaded with solid matter, that, 
though its temperature were 90°, yet, by reason of the 
quantity of such matter held in solution, its specific 
gravity might have been greater even than that of extra- 
tropical sea water generally at 28°. 


THE SALTS OF THE SEA. DZ 


Notwithstanding this, it may be brought into contact, 
by the way, with those kinds and quantities of marine 
organisms that shall abstract solid matter enough to re- 
duce its specific gravity, and, instead of leaving it greater 
than common sea water at 28°, make it less than common 
sea water at 39°; consequently, in such a case, this warm 
sea water, when it comes to the cold latitudes, would be 
brought to the surface through the instrumentality of 
shell-fish, and various other tribes that dwell far down in 
the depths of the ocean. Thus we perceive that these 
creatures, though they are regarded as being so low in 
the scale of creation, may nevertheless be regarded as 
agents of much importapce in the terrestrial economy ; 
for we now comprehend how they are capable of spread- 
ing over certain parts of the ocean those benign mantles 
of warmth which temper the winds, and modify, more or 
less, all the marine climates of the earth. 

The makers of nice astronomical instruments, when 
they have put the different parts of their machinery to- 
gether, and set it to work, find, as in the chronometer, 
for instance, that it is subject in its performance to many 
irregularities and imperfections; that in one state of 
things there is expansion, and in another state contrac- 
tion, among cogs, springs, and wheels, with an increase or 
diminution of rate. This defect the makers have sought 
to overcome ; and, with a beautiful display of ingenuity, 
they have attached to the works of the instrument a 
contrivance which has had the effect of correcting these 
irregularities, by counteracting the tendency of the in- 
strument to change its performance with the changing 
influences of temperature. 


CHAPTER 
IX. 


§ 557 


This warn 
water, 
when it 
reaches 
cold lati- 
tudes, 
would be 
brought to 
the surface 
by sheli- 


fish. 


§ 538 
3eautiful 
and simple 

contriv- 
ance to re- 
gulate 
chronoine- 
ters. 


CHAPTER 
[X. 
§,599 
Compen- 
sation. 


§ 560 


Analogy 
in the 
machinery 
of the uni- 
verse. 


§ 561 


Also in the 
machinery 
of the 
ocean, 


§ 562 


Result if 
there were 
no com- 
pensation. 


§ 563 


Compen- 
sation 
found in 
sea shells 
and the 
works of 
marine in- 
sects. 


236 THE PHYSICAL GEOGRAPHY OF THE SEA. 


This contrivance is called a compensation ; and a chro. 
nometer that is well regulated and properly compensated 
will perform its office with certainty, and preserve its 
rate under all the vicissitudes of heat and cold to which 
it may be exposed. 

In the clock-work of the ocean and the machinery of 
the universe, order and regularity are maintained by a 
system of compensations. A celestial body, as it revolves 
around its sun, flies off under the influence of centrifugal 
force ; but immediately the forces of compensation begin 
to act; the planet is brought back to its elliptical path, 
and held in the orbit for which its mass, its motions, and 
its distance, were adjusted. Its compensation is perfect. 

So, too, with the salts and the shells of the sea in the 
machinery of the ocean; from them are derived principles 
of compensation the most perfect ; through their agency 
the undue effects of heat and cold, of storm and rain, in 
disturbing the equilibrium, and producing thereby cur- 
rents in the sea, are compensated, regulated, and con- 
trolled. 

The dews, the rains, and the rivers, are continually 
dissolving certain minerals of the earth, and carrying 
them off to the sea. This is an accumulative process ; 
and if it were not compensated, the sea would finally 
become, as the Dead Sea is, saturated with salt, and 
therefore unsuitable for the habitation of many fish of 
the sea. 

The sea shells and marine insects afford the required 
compensation. They are the conservators of the ocean. 
As the salts are emptied into the sea, these creatures 
scerete them again, and pile them up in solid masses, to 


THE SALTS OF THE SEA. 237 


serve as the bases of islands and continents, to be in the 
process of ages upheaved into dry land, and then again 
dissolved by the dews and rains, and washed by the rivers 
away into the sea. 

The question as to whence the salts of the sea were 
originally derived, of course has not escaped the attention 
of philosophers. 

I once thought with Darwin and those other philoso- 
phers who hold that the sea derived its salts originally 
from the washings of the rains and rivers. I now ques- 
tion that opinion; for, in the course of the researches 
connected with the “ Wind and Current Charts,” I have 
found evidence, from the sea and in the Bible, which 
seems to cast doubt upon it. The account given in the 
first chapter of Genesis, and that contained in the hiero- 
glyphics which are traced by the hand of Nature on the 
geological column as to the order of creation, are marvel- 
lously accordant. The Christian man of science regards 
them both as true; and he never overlooks the fact that, 
while they differ in the mode and manner as well as in 
the things they teach, yet they never conflict ; and they 
contain no evidence going to show that the sea was ever 
fresh ; on the contrary, they both afford circumstantial 
evidence sufficient for the belief that the sea was salt as 
far back as the morning of creation, or at least as the 
evening and the morning of the day when the dry land 
appeared. 

That the rains and the rivers do dissolve salts of vari- 
ous kinds from the rocks and soil, and empty them into 
the sea, there is no doubt. These salts cannot be eva- 
porated, we know ; and we also know that many of the 


CHAPTER 
IX. 


§ 564 
Sea salts, 
whence 
derived. 


Darwin's 
opinion. 


The Bible 


The sea 
was salt 
from the 
beginning. 


§ 565 
Salts can- 
not be eva- 
porated, 


CHAPTER 


LX. 


Solids of 


the sea 
tracted 


ex- 
by 


other pro- 
cesses than 
evapora- 


Sion, 


§5 


66 


Proofs that 


these ope- 


rations 
still go 


on. 


238 THE PHYSICAL GEOGRAPHY OF THE SEA. 


lakes, as the Dead Sea, which receive rivers and have no 
outlet, are salt. Hence the inference by some philoso- 
phers' that these inland water-basins received their salts 
from the washings of the soil; and consequently the con- 
jecture arose that the great sea derived its salts from the 
same source and by the same process. But, and per 
contra, though these solid ingredients cannot be taken 
out of the sea by evaporation, they can be extracted by 
other processes. We know that the insects of the sea do 
take out a portion of them; and that the salt ponds and 
arms which, from time to time in the geological calendar, 
have been separated from the sea, afford an escape by 
which the quantity of chloride of sodium in its waters— 
the most abundant of its solid ingredients—is regulated. 
The insects of the sea cannot build their structures of 
this salt, for it would dissolve again, and as fast as they 
could separate it. But here the ever-ready atmosphere 
comes into play, and assists the insects in regulating the 
salts. It cannot take them up from the sea, it is true, 
but it can take the sea away from them; for it pumps 
up the water from these pools that have been barred off, 
transfers it to the clouds, and they deliver it back to the 
sea as fresh water, leaving the salts it contained in a solid 
state behind. 

These are operations that have been going on for ages : 
proof that they are still going on is continually before 
our eyes; for the “hard water” of our fountains, the 
marl-banks of the valleys, the salt-beds of the plains, 
Albion’s challxy cliffs, and the coral islands of the sea, are 
monuments in attestation. 


There is no proof, nor is there any reason for the belief, 


THE SALTS OF THE SEA 239 


that the sea is growing salter or fresher. Hence we infer 
that the operations of addition and extraction are reci- 
procal and equal,—that the effect of rains and rivers in 
washing down is compensated by the processes of evapo- 
ration and secretion in taking out. 

If the sea derived its salts originally from the rivers, 
the geological records of the past would show that river 
beds were scored out in the crust of our planet before the 
sea had deposited any of its fossi! shells and infusorial 
remains upon it. If, therefore, we admit the Darwin 
theory, we must also admit that there was a period when 
the sea was without salt, and consequently without shells 
or animals either of the silicious or calcareous kind. If 
ever there were such a time, it must have been when the 
rivers were collecting and pouring in the salts which now 
make the brine of the ocean. But while the paleeonto- 
logical records of the earth, on one hand, afford no evidence 
of any such fresh-water period, the Mosaic aceount is far 
from being negative with its testimony on the other. 
According to it, we infer that the sea was salt as early, 
at least, as the fifth day ; for it was on that day of crea- 
tion that the waters were commanded to “ bring forth 
abundantly the moving creature that hath life.” It is in 
obedience to that command that the sea now teems with 
organisms ; and it is marvellous how abundantly the obe- 
dient waters do bring forth, and how wonderful for variety 
as well as multitude their progeny is. All who pause to 
look are astonished to see how the prolific ocean teems 
and swarms with life. The moving creatures in the sea 
constitute in their myriads of multitudes one of the “ won- 
ders of the deep.” 


CHAPTER 
Ix, 


Sea grows 
neither 
salter nor 
fresher. 


§ 568 
Inference. 
Objections 
to the 
Darwin 
theory 


Deduc- 
tions from 
Mosaic ac- 
count 


CHAPTER 
IX. 
$ 569 
Captain 
Foster's 
observa- 
tions. 


“Wonders 
of the 
deep.” 


Animal- 
cule. 


§ 571 
The two 
records 
agree. 


240 THE PHYSICAL GEOGRAPHY OF THE SEA, 


It is the custom of Captain Foster, of the American 
ship Garrick, who is one of my most patient of ob- 
servers, to amuse himself by making drawings in his 
abstract log of the curious animalcule which, with the 
microscope, he finds in the surface water alongside; and 
though he has been following the sea for many years, he 
never fails to express his wonder and amazement at the 
immense numbers of living creatures that the microscope 
reveals to him in sea water. Hitherto his examinations 
related only to the surface waters, but in the log now 
before me he went into the depths, and he was more 
amazed than ever to see how abundantly the waters even 
there bring forth. 

“ Jan. 28th, 1855.—In examining animalcule in 
sea water, I have,” says he, “ heretofore used surface 
water. This afternoon, after pumping for some time 
from the stern pump seven feet below the surface, I 
examined the water, and was surprised to find that the 
fluid was literally alive with animated matter, embracing 
beautiful varieties.” Of some he says, “ Numerous heads, 
purple, red, and variegated.” | 

There is wonderful meaning in that word ABUNDANTLY, 
as it stands recorded in that Book, and as it is even at 
this day repeated by the great waters. 

So far the two records agree; and the evidence is clear 
that the sea was salt when it received this command. 
Do they afford any testimony as to its condition previ- 
ously? Let us examine. 

On the third day of creation the waters were gathered 
together unto one place, and the dry land appeared. 
Before that period, therefore, there were no rivers, and 


THE SALTS OF THE SEA. 241 


consequently no washings of brine, by mists, nor dew, nor 
rains, from the valleys among the hills. The water covered 
the earth. This is the account of Revelation; and the 
aecount which Nature has written, in her own peculiar 
characters, on the mountain and in the plain, on the rock 
and in the sea, as to the early condition of our planet, 
indicates the same. The inscriptions on the geological 
column tell that there was a period when the solid parts 
of the earth’s crust, which now stand high in the air, 
were covered by water. The geological evidence that it 
was so, with perhaps the exception of a solitary mountain 
peak here and there, is conclusive; and when we come 
to examine the fossil remains that are buried in the 
mountains and scattered over the plains, we have as 
much reason to say that the sea was salt when it covered, 
or nearly covered, the earth, as the naturalist, when he 
sees a skull or bone whitening on the wayside, has to 
say that it was once covered with flesh. 

Therefore we have reason for the conjecture, that the 
sea was salt “in the beginning,” when “the waters 
under heaven were gathered together unto one place,” 
and the dry land first appeared. For, go back as far as 
we may in the dim records which young Nature has left 
inscribed upon the geological column of her early pro- 
cesses, and there we find the fossil shell and the remains 
of marine organisms to inform us that, when the founda- 
tions of our mountains were laid with granite, and imme- 
diately succeeding that remote period when the primary 
formations were completed, the sea was, as it is now, 
salt: for, had it not been salt, whence could those creep- 


ing things which fashioned the sea shells that cover the 
16 


CHAPTER 
IX. 


Deduc- 
tions from 
Revelation 
and Na- 
ture. 


§ 572 
Conjecture 
that the 
sea was 
salt from 
the begin 
ning. 


Reasons 
for this. 


CHAPTER 
IX, 


Effects of 
marine 
salts on 
eultiva- 
tion. 


§ 573 
Self-ad- 
justing 
principle 
of nature. 


§ 574 


242 THE PHYSICAL GEOGRAPHY OF THE SEA. 


tops of the Andes, or those madrepores that stiew the 
earth with solid matter that has been secreted from briny 
waters, or those infusorial deposits which astound the 
geologist with their magnitude and extent, or those fossil 
remains of the sea which have astonished, puzzled, and 
bewildered man in all ages; whence, had not the sea 
been salt when its metes and bounds were set, could these 
creatures have obtained solid matter for their edifices and 
structures? Much of that part of the earth’s crust which 
man stirs up in cultivation, and which yields him bread, 
has been made fruitful by these “salts,” which all man- 
ner of marine insects, aqueous organisms, and sea shells, 
have secreted from the ocean. Much of this portion of 
our planet has been filtered through the sea; and its 
insects and creeping things are doing now precisely what 
they were set about when the dry land appeared,— 
namely, preserving the purity of the ocean, and regulating 
it in the due performance of its great offices. As fast as 
the rains dissolve the salts of the earth, and send them 
down through the rivers to the sea, these faithful and 
everlasting agents of the Creator elaborate them into 
pearls, shells, corals, and precious things ; and so, while 
they are preserving the sea, they are also embellishing 
the land, by imparting new adaptations to its soil, fresh 
beauty and variety to its landscapes. 

In every department of nature there is to be found 
this self-adjusting principle, this beautiful and exquisite 
system of compensation, by which the operations of the 
grand machinery of the universe are maintained in the 
most perfect order. 


Whence came the salts of the sea originally, is a ques- 


THE SALTS OF THE SEA. 243 
tion which, perhaps, never will be settled satisfactorily to 
every philosophic mind; but it is sufficient for the Chris- 
tian philosopher to recollect that the salts of the sea, like 


its waters and the granite of the hills, are composed of 


substances which, when reduced to their simple state, are 
found, for the most part, to be mere gaseous or volatile 
matter of some kind or other. Thus we say that granite 
is generally composed of felspar, mica, and quartz; yet 
these three minerals are made of substances more or less 
volatile in combination with oxygen gas. Iron, of which 
there is merely a trace, is the only ingredient which, in 
its uncombined and simple state, is not gaseous or vola- 
tile. Now, was the felspar of the granite originally 
formed in one heap, the mica in another, and the quartz 
in a third, and then the three brought together by some 
mighty power, and welded into the granitic rock for the 
everlasting hills to stand upon; or were they made into 
rock as they were formed of the chaotic matter ? 

Sea water is composed of oxygen and hydrogen ; and 
its salts, hke the granite, also consist of gases and vola- 
tile matters. But whether the constituents of sea water, 
like those of the primitive rocks, were brought together 
in the process of formation, and united in combination as 
we now find them in the ocean, or whether the sea was 
fresh “in the beginning,” and became salt by some sub- 
sequent process, is not material to our present purpose. 
Some geologists suppose that in the chalk period, when 
the ammonites, with their huge chambered shells, lived 
in the sea, the carbonaceous material required by these 
creatures for their habitations must have been more abun- 
dant in its waters than it now is; but, though the con- 


CHAPTER 
Ix. 


Composi- 
tion of the 
salts of the 
sca. 


§ 575 


Supposi- 
tion re- 
garding 
the chalk 
period. 


CHAPTER 
IX. 


§ 576 
The cuttle- 
fish. 


The nauti- 
lus and 
coral in- 
sect. 


§ 577 


Computa- 
tion of 
solid mat- 
ter held in 
solution as 
falts. 


244 THE PHYSICAL GEOGRAPHY OF THE SEA. 


stituents of sea water may have varied as to proportions, 
they probably were never, at least since “its waters 
commenced to bring forth,” widely different from what 
they now are. 

It is true, the strange cuttle-fish, with its shell twelve 
feet in circumference, is no longer found alive in the sea ; 
it died out with the chalk period: but then its compa- 
nion, the tiny nautilus, remains to tell us that even in 
that remote period the proportion of salt in sea water 
was not unsuited to its health ; for it and the coral insect 
have lived through all the changes that our planet has 
undergone since the sea was inhabited, and they tell us 
that its waters were salt as far back, at least, as their 
records extend, for they now build their edifices and 
make their habitations of the same materials, collected 
in the same way, that they did then; and had the sea 
been fresh in the interim, they too would have perished, 
and their family would have become extinct, like that of 
the great ammonite, which perhaps ceased to find the 
climates of the sea, not the proportion of its salts, suited 
to its well-being. 

Did any one, who maintains that the salts of the sea 
were originally washed down into it by the rivers and 
the rains, ever take the trouble to compute the quantity 
of solid matter that the sea holds in solution as salts? 
Taking the average depth of the ocean at two miles, and 
its average saltness at 3% per cent., it appears that there 
is salt enough in the sea to cover to the thickness of one 
mile an area of seven millions of square miles. Admit a 
transfer of such a quantity of matter from an average of 
half a mile above to one below the sea level, and astro- 


THE SALTS OF THE SEA. 245 


nomers will show, by calculation, that it would alter the cxarree 
IX. 
length of the day. sae 
These seven millions of cubic miles of crystal salt have This does 


not in- 


not made the sea any fuller. All this solid matter has crease the 
heen received into the interstices of sea water without water 
swelling the mass; for chemists tell us that water is not 
increased in volume by the salt it dissolves. Here is, 
therefore, started up before us an economy of space cal- 
culated to surprise even the learned author himself of the 

“ Plurality of Worlds.” 

There has been another question raised which bears § 578 
upon what has already been said concerning the offices 
which, in the sublime system of terrestrial arrangements, 
have been assigned to the salts of the sea. 

On the 20th of January, 1855, Professor Chapman, of § 579 
the University College, Toronto, communicated to the Cae 


Canadian Institute a paper on the “Object of the Salt v's 


theory on 


Condition of the Sea ;” which, he maintains, is “mainly Heian 
of the salt 


intended to regulate evaporation.” To establish this ness of the 
hypothesis, he shows, by a simple but carefully conducted a 

set of experiments, that the salter the water, the slower 

the evaporation from it; and that the evaporation which 

takes place in twenty-four hours from water about as salt 

as the average of sea water, is 0.54 per cent. less in 
quantity than from fresh water. 

“ This suggestion, and these experiments, give additiona! 
interest to our investigations into. the manifold and mar- 
vellous offices which, in the economy of our planet, have 
been assigned by the Creator to the salts of the sea. It 
is difficult to say what, in the divine arrangement, was 
the main object of making the sea salt, and not fresh. 


THAPTER 
1X. 


Thoughts 
suggested 
by the Pro- 
fessor’s 
theory. 


246 THE PHYSICAL GEOGRAPHY OF THE SEA. 


Whether it was to assist in the regulation of climates, or 
in the circulation of the ocean, or in re-adapting the earth 
for new conditions, by transferring solid portions of its 
crust from one part to another, and giving employment 
to the corallines and insects of the sea in collecting this 
solid matter into new forms, and presenting it under 
different climates and conditions; or whether the main 
object was, as the distinguished Professor suggests, to 
regulate evaporation, it is not necessary now or here to 
discuss. I think we may regard all the objects of the 
salts of the sea as main objects. 

“But we see in the Professor’s experiments the dawn 
of more new beauties, and the appearance of other exqui- 
site compensations, which, in studying the ‘wonders of 
the deep,’ we have so often paused to contemplate and 
admire. As the trade-wind region feeds the air with the 
vapour of fresh water, the process of evaporation is 
checked, for the water which remains, being salter, parts 
with its vapour less readily ; and thus, by the salts of the 
sea, floods may be prevented. But again; if the evapo- 
rating surface were to. grow salter and salter, whence 
would the winds derive vapour duly to replenish the 
earth with showers? for the salter the surface, the more 
scanty the evaporation. Here is compensation, again, 
the most exquisite; and we perceive how, by reason of 
the salts of the sea, drought and famine, if not prevented, 
may be, and probably are, regulated and controlled: for 
that compensation which assists to regulate the amount 
of evaporation, is surely concerned in adjusting also the 
quantity of rain. Were the salts of the sea lighter in- 
stead of heavier than the water, they would, as they feed 


THE SALTS OF THE SEA. 247 


the winds with moisture for the cloud and the rain, re- 
main at its surface, and become more niggardly in their 
supplies, and finally, the winds would howl over the sea 
in very emptiness ; and instead of cool and refreshing sea 
breezes to fan the invalid and nourish the plants, we 
should have the gentle trade-wind coming from the sea 
in frightful blasts of parched, and thirsty, and blighting 
air. But the salts, with their manifold and marvellous 
adaptations, come in here as a counterpoise, and, as the 
waters attain a certain degree of saltness, they become 
too heavy to remain longer in contact with the thirsty 
trade-winds, and are carried down, because of their salts, 
into the depths of the ocean; and thus the winds are 
dieted with vapour in due and wholesome quantities. 
“In this view of the subject, and for the purpose of 
earrying on the investigations which Professor Chapman’s 
interesting paper suggests, observations upon the specific 
gravity of sea water become still more interesting. It is 
to be hoped, therefore, that my fellow-labourers at sea 
will not slight the specific gravity column of the man-of- 
—Mavry’s Sailing Directions, 7th ed, 


2 


war abstract log.’ 
p. 857. 

Thus we behold sea shells and animalcule in a new 
light. May we not now cease to regard them as beings 
which have little or nothing to do in maintaining the 
harmonies of creation? On the contrary, do we not see 
in them the principles of the most admirable compensa- 
tion in the system of oceanic circulation? We may even 
regard them as regulators, to some extent, of climates in 
parts of the earth far removed from their presence. There 
is something suggestive both of the grand and the beau- 


CHAPTER 
IX. 


Value of 
observa- 
tions onthe 
specific 
gavity of 
sea wafer. 


$ 580 


Uses of 
shells and 
animal- 
cule. 


CHAPTER 
Ix. 


$ 581 


248 THE PHYSICAL GEOGRAPHY OF THE SEA. 


tiful, in the idea that, while the insects of the sea are 
building up their coral islands in the perpetual summer 
of the tropics, they are also engaged in dispensing warmth 
to distant parts of the earth, and in mitigating the severe 
cold of the Polar winter. 

Surely an hypothesis which, being followed out, sug- 
gests so much design, such perfect order and arrangement, 
and so many beauties for contemplation and admiration, 
as does this, which, for the want of a better, I have 
ventured to offer with regard to the solid matter of the 
sea water, its salts and its shells—surely such an hypo- 
thesis, though it be not based entirely on the results of 
actual observation, cannot be regarded as wholly vain, 
or as altogether profitless. 


THE EQUATORIAL CLOUD-RING. 249 


CHAPTER X. 


THE EQUATORIAL CLOUD-RING. 


The “ Doldrums,” § 583.—Oppressive Weather, 586.—Offices of the Clouds, 
587.—Weight for the Wind, 589.—Galileo and the Pump-maker, 590.—Tem- 
perature and Pressure under the Cloud-ring, 591.—Its effect upon Climate, 
596.—Its Offices, 599.—Whence come the Vapours that form the Cloud-ring ? 
602.—Its appearance, 605. 


SEAFARING people have, as if by common consent, divided 
the ocean off into regions, and characterized them accord- 
ing to the winds: e. g., there are the “ trade-wind regions,” 
the “variables,” the “horse latitudes,” the “doldrums,” 
&e. The “horse latitudes” are the belts of calms and 
light airs' which border the Polar edge of the north-east 
trades. They were so called from the circumstance that 
vessels formerly bound from New England to the West 
Indies, with a deck-load of horses, were often so delayed 
in this calm belt of Cancer, that, for the want of water 
for their animals, they were compelled to throw a portion 
of them overboard. 

The “equatorial doldrums” is another of these calm 
places.” Besides being a region of calms and baffling 
winds, it is a region noted for its rains and clouds, 
which make it one of the most oppressive and disagree- 
able places at sea. The emigrant ships from Europe for 
Australia have to cross it. They are often bafHed in it 
for two or three weeks ; then the children, and the pas- 
sengers who are of delicate health, suffer most. It is 
a frightful graveyard on the way-side to that golden 
land. 


7 § 131. 2 $135. 


CHAPTER 
X. 


§ 582 


The horse 
latitudes. 


$ 583 


The dol- 
drums. 


Its bad 
climate. 


250 THE PHYSICAL GEOGRAPHY OF THE SEA. 


A vessel bound into the southern hemisphere from 
Europe or America, after clearing the region of variable 
winds and crossing the “horse latitudes,” enters the 
north-east trades. Here the mariner finds the sky some- 
times mottled with clouds, but for the most part clear. 
Here, too, he finds his barometer rising and falling under 
the ebb and flow of a regular atmospherical tide, which 
gives a high and low barometer every day with such 
regularity, that the hour, within a few minutes, may be 
told by it. The rise and fall of this tide, measured by 
the barometer, amounts to about one-tenth (0.1) of an 
inch, and it occurs daily, and everywhere between the 
tropics; the maximum about ]0h. 30m. A.M, the mini- 
mum between 4h. and 5h. P.M. with a second maximum 
and minimum about 10 P.M. and 5 AmM* The diurnal 
variation of the needle changes also with the turning of 
these invisible tides. Continuing his course toward the 
equinoctial line, the navigator observes his thermometer 
to rise higher and higher as he approaches it; at last, 
entering the region of equatorial calms and rains, he feels 
the weather to become singularly close and oppressive ; 
he discovers here that the elasticity of feeling which he 
breathed from the trade-wind air has forsaken him; he 
has entered the doldrums, and is under the “ cloud-ring.” 

Escaping from this gloomy region, and entering the 
south-east trades beyond, his spirits revive, and he turns 
to his log-book to see what changes are recorded there. 
He is surprised to find that, notwithstanding the oppres- 
sive weather of the rainy latitudes, both his thermometer 


* See paper on Meteorological Observations in India, by Colonel Sykes, Philo- 
sophical Transactions for 1850, part ii., page 297. 


THE EQUATORIAL CLOUD-RING. ay] 


and barometer stood, while in them, lower than in the carrer 
clear weather on either side of them; that just before en- ee 
tering, and just before leaving the rainy parallels, the 
mercury of the thermometer and barometer invariably 
stands higher than it does when within them, even 
though they include the equator. In crossing the equa- 
torial doldrums, he has passed a ring of clouds that 
encircles the earth. 

I find in the journal of the late Commodore Arthur § 586 
Sinclair, kept on board the United States frigate Con- Peserip- 


tion of it 
gress, during a cruise to South America in 1817-18, a by Com 


picture of the weather under this cloud-ring that is sin- Sinclat i 
gularly graphic and striking. He encountered it in the Th 
month of January 1818, between the parallel of 4° north 
and the equator, and between the meridians of 19° and 
23° west. He says of it:— 

“This is certainly one of the most unpleasant regions 
in our globe. A dense, close atmosphere, except for a few 
hours after a thunder-storm, during which time torrents 
of rain fall, when the air becomes a little refreshed ; but 
a hot, glowing sun soon heats it again, and but for 
your awnings, and the little air put in circulation by the 
continual flapping of the ship’s sails, it would be almost 
insufferable. No person who has not crossed this region 
can form an adequate idea of its unpleasant effects. You 
feel a degree of lassitude unconquerable, which not even 
the sea-bathing, which everywhere else proves so salutary 
and renovating, can dispel. Except when in actual dan- 
ver of shipwreck, I never spent twelve more disagreeable 
days in the professional part of my life than in these 
calm latitudes. 


CHAPTER 
X. 


§ 587 
Various 
offices per- 
formed by 
clouds. 


Vhey mo- 
slerate ex- 
tremes of 
heat and 
cold, 


Zoi2 THE PHYSICAL GEOGRAPHY OF THE SEA. 


“T crossed the line on the 17th of January, at eicht 
AM. in longitude 21° 20’, and soon found I had sur- 
mounted all the difficulties consequent to that event ; that 
the breeze continued to freshen and draw round to the 
south south-east, bringing with it a clear sky and most 
heavenly temperature, renovating and refreshing beyond 
description. Nothing was now to be seen but cheerful 
countenances, exchanged as by enchantment from that 
sleepy sluggishness which had borne us all down for the 
last two weeks.” 

One need not go to sea to perceive the grand work 
which the clouds perform in collecting moisture from the 
crystal vaults of the sky, in sprinkling it upon the fields, 
and making the hills glad with showers of rain. Winter 
and summer, “the clouds drop fatness upon the earth.” 
This part of their office is obvious to all, and I do not 
propose to consider it now. But the sailor at sea observes 
phenomena and witnesses operations in the terrestrial 
economy which tell him that, in the beautiful and ex- 
quisite adjustments of the grand machinery of the atmo- 
sphere, the clouds have other important offices to perform 
besides those merely of dispensing showers, of producing 
the rains, and of weaving mantles of snow for the pro- 
tection of our fields in winter. As important as are these 
offices, the philosophical mariner, as he changes his sky, 
is reminded that the clouds have commandments to fulfil, 
which, though less obvious, are not therefore the less 
benign in their influences, or the less worthy of his notice. 
He beholds them at work in moderating the extremes of 
heat and cold, and in mitigating climates. At one time 


they spread themselves out ; they cover the earth as with 


THE EQUATORIAL CLOUD-RING. 253 


a mantle; they prevent radiation from its crust, and keep 
it warm. At another time, they interpose between it 
and the sun; they screen it from his scorching rays, and 
protect the tender plants from his heat, the land from the 
drought ; or, ike a garment, they overshadow the sea, 
defending its waters from the intense forces of evaporation. 
Having performed these offices for one place, they are 
evaporated, and given up to the sunbeam and the winds 
again, to be borne on their wings away to other places 
which stand in need of like offices. 

Familiar with clouds and sunshine, the storm and the 
calm, and all the phenomena which find expression in the 
physical geography of the sea, the right-minded mariner, 
as he contemplates “the cloud without rain,” ceases to 
regard it as an empty thing ; he perceives that it performs 
many important offices; he regards it as a great mode- 
rator of heat and cold—as a “compensation” in the at- 
mospherical mechanism which makes the performance of 
the grand machine perfect. 

Marvellous are the offices, and wonderful is the consti- 
tution, of the atmosphere. Indeed, I know of no subject 
more fit for profitable thought on the part of the truth- 
loving, knowledge-seeking student, be he seaman or lands- 
man, than that afforded by the atmosphere and its offices. 
Of all parts of the physical machinery, of all the con- 
trivances in the mechanism of the universe, the atmosphere, 
with its offices and its adaptations, appears to me to be 
the most wonderful, sublime, and beautiful. In its con- 
struction, the perfection of knowledge is involved. The 
perfect man of Uz, in a moment of inspiration, thus 
bursts forth in laudation of this part of God’s handiwork, 


CHAPTER 
x. 


§ 588 


§ 589 


Wonderful 
constitu- 
tion of the 
atmo- 
sphere. 


CHAPTER 
xX. 


§ 590 
Galileo 
and the 


pump- 
maker. 


§ 591 


Os + THE PHYSICAL GEOGRAPHY OF THE SEA. 


demanding of his comforters: “ But where shall wisdom 
be found? and where is the place of understanding? The 
depth saith, It is not in me; and the sea saith, It is not 
with me. It cannot Le gotten for gold, neither shall 
silver be weighed for the price thereof. No mention 
shall be made of coral, or of pearls: for the price of 
wisdom is above rubies. Whence then cometh wisdom ? 
and where is the place of understanding? Destruction 
and death say, We have heard the fame thereof with our 
ears. God understandeth the way thereof, and he knoweth 
the place thereof. For he looketh to the ends of the 
earth, and seeth under the whole heaven; to make the 
weight for the winds; and he weigheth the waters by 
measure. When he made a decree for the rain, and a 
way for the lightning of the thunder; then did he see 
it, and declare it; he prepared it, yea, and searched it 
out.”* 

When the pump-maker came to ask Galileo to explain 
how it was that his pump would not lift water higher 
than thirty-two feet, the philosopher thought, but was 
afraid to say, it was owing to “ weight of the winds ;” 
and though the fact that the air has weight is here so 
distinctly announced, philosophers never recognised the 
fact until within comparatively a recent period, and then 
it was proclaimed by them as a ‘great discovery. Never- 
theless, the fact was set forth as distinctly in the book of 
nature as it is in the book of revelation; for the infant, 
in availing itself of atmospherical pressure to draw milk 
from its mother’s breast, unconsciously proclaimed it. 

Both the thermometer and the barometer’ stand lower 


* Job, chap. xxviii. 
1 § 585. 


THE EQUATORIAL CLOUD-RING. Ze 


under this cloud-ring than they do on either side of it. 
After having crossed it, and referred to the log-book to 
refresh his mind as to the observations there entered with 
regard to it, the attentive navigator may perceive how 
this belt of clouds, by screening the parallels over which 
he may have found it to hang from the sun’s rays, not 
only promotes the precipitation which takes place within 
these parallels at certain periods, but how, also, the rains 
are made to change the places upon which they are to 
fall; and how, by travelling with the calm belt of the 
equator up and down the earth, this cloud-ring shifts the 
surface from which the heating rays of the sun are to be 
excluded ; and how, by this operation, tone is given to 
the atmospherical circulation of the world, and vigour to 
its vegetation. 

Having travelled with the calm belt to the north or 
south, the cloud-ring leaves the sky about the equator 
clear ; the rays of the torrid sun pour down upon the 
crust of the earth there, and raise its temperature to a 
scorching heat. , The atmosphere dances, and the air is 
seen trembling in ascending and descending columns, with 
busy eagerness to conduct the heat off, and deliver it to 
the regions aloft, where it is required to give momentum 
to the air in its general channels of circulation. The dry 
season continues; the sun is vertical; and finally the 
earth becomes parched and dry; the heat accumulates 
faster than the air can carry it away; the plants begin 
to wither, and the animals to perish. Then comes the 
mitigating cloud-ring. The burning rays of the sun are 
intercepted by it: the place for the absorption and reflec- 
tion, and the delivery to the atmosphere of the solar heat, 


1 § 352, 


CHAPTER 
x. 


Thermo- 
meter and 
barometer 
stand 
lower in 
cloud-ring 
than on 
either side 
of it. 


§ 592 


Tempera- 

ture unde 
the cloud- 
ring. 


CHAPTER 
x. 


$ 593 


Radiation. 


§$ 594 


Operations 
of the 
trade- 
winds in 
this 
cloud-belt. 


Vapours 
condensed 
on the 
lower side. 


§ 595 
Process on 


the upper 
side. 


256 THE PHYSICAL GEOGRAPHY OF THE SEA. 


is changed ; it is transferred from the upper surface of tlie 
earth to the upper surface of the clouds. 

Radiation from land and sea below the cloud-belt is thus 
interrupted, and the excess of heat in the earth is delivered 
to the air, and by absorption carried up to the clouds, and 
there transferred to their vapours to prevent excess of 
preciptation. 

In the meantime, the trade-winds, north and south, are 
pouring into this cloud-covered receiver, as the calm and 
rain-belt of the equator may be called, fresh supplies in 
the shape of ceaseless volumes of heated air, which, load- 
ed to saturation with vapour, has to rise above and get 
clear of the clouds before it can commence the process of 
cooling by radiation. In the meantime, also, the vapours 
which the trade-winds bring from the north and the 
south, expanding and growing cooler as they ascend, are 
being condensed on the lower side of the cloud stratum, 
and their latent heat is set free, to check precipitation 
and prevent a flood. 

While this process and these operations are going on 
upon the nether side of the cloud-ring, one not less 
important is, we may imagine, going on upon the upper 
side. There, from sunrise to sunset, the rays of the sun 
are pouring down without intermission. Every day, and 
all day long, they play with ceaseless activity upon the 
upper surface of the cloud stratum. When they become 
too powerful, and convey more heat to the cloud vapours 
than the cloud vapours can reflect and give off to the 
air above them, then, with a beautiful elasticity of 
character, the clouds absorb the surplus heat. They meli 
away, become invisible, and retain, in a latent and harm- 


THE EQUATORIAL CLOUD-RING. VAS 


less state, until it is wanted at some other place, and on 
some other occasion, the heat thus imparted. 

We thus have an insight into the operations which are 
going on in the equatorial belt of precipitation, and this 
insight is sufficient to enable us to perceive that exquisite 
indeed are the arrangements which Nature has provided 
for supplying this calm belt with heat, and for pushing 
the snow-line there high up above the clouds, in order 
that the atmosphere may have room to expand, to rise 
up, overflow, and course back into its channels of health- 
ful circulation. As the vapour is condensed and formed 
into drops of rain, a twofold object is accomplished: coming 
from the cooler regions of the clouds, the rain-drops are 
evoler than the air and earth below; they descend, and 
by absorption take up the heat which has been accumu- 
lating in the earth’s crust during the dry season, and 
which cannot now escape by radiation. Thus this cloud- 
ring modifies the climate of all places beneath it; over- 
shadowing, at different seasons, all parallels from 5° south 
to 15° north. 

In the process of condensation, these rain-drops, on the 
other hand, have set free a vast quantity of latent heat, 
which has been gathered up with the vapour from the 
sea by the trade-winds and brought hither. The caloric 
thus liberated is taken by the air and carried up aloft 
still farther, to keep, at the proper distance from the 
earth, the line of perpetual congelation. Were it possible 
to trace a thermal curve in the upper regions of the air 
to represent this line, we should no doubt find it mounting 
sometimes at the equator, sometimes on this side, and 


sometimes on that of it, but always so mounting as to 
17 


CHAPTER 


§ 596 

Beautiful 
arrange- 
ments of 


nature for 
supplying 


this calm 
belt with 
heat. 


It modifies 


climate. 


Supposed 
thermal 
curve. 


» 
- 


CHAPTER 
xX. 


Its course. 


§ 598 


§ 599 
Contem- 
plation of 
the offices 
of the 
cloud-belt. 


§ 600 


It regu- 
lates heat 
uud ad- 
justs the 
winds. 


258 THE PHYSICAL GEOGRAPHY OF THE SEA. 


overleap this cloud-ring. This thermal line would not 
ascend always over the same parallels: it would ascend 
over those between which this ring happens to be: and 
the distance of this ring from the equator, north or south, 
is regulated according to the seasons. 

If we imagine the atmospherical equator to be always 
where the calm belt is, which separates the north-east from 
the south-east trade-winds, then the loop in the thermal 
curve, which should represent the line of perpetual con- 
gelation in the air, would be always found to stride this 
equator; and it may be supposed that a thermometer, 
kept sliding on the surface of the earth so as always to 
be in the middle of this rain-belt, would show very nearly 
the same temperature all the year round; and so, too, 
would a barometer the same pressure. 

Returning and taking up the train of contemplation as 
to the office which this belt of clouds, as it encircles the 
earth, performs in the system of oceanic adaptations, we 
may see how the cloud-ring and calm zone which it over- 
shadows perform the office both of ventricle and auricle 
in the immense atmospherical heart, where the heat and 
the forces which give vitality and power to the system 
are brought into play—where dynamical strength is 
gathered, and an impulse given to the air sufficient to 
send it thence through its long and tortuous channels of 
circulation. 


Thus this ring, or band, or belt of clouds, is stretched 


oO 
around our planet to regulate the quantity of precipita- 
tion in the rain-belt beneath it; to preserve the due 
quantum of heat on the face of the earth; to adjust the 


winds, and send out for distribution to the four corners, 


THE EQUATORIAL CLOUD-RING. 259 


vapours in proper quantities to make up to each river- 
basin, climate, and season, its quota of sunshine, cloud, 
and moisture. Like the balance-wheel of a well con- 
- constructed chronometer, this cloud-ring affords the grand 
atmospherical machine the most exquisitely-arranged self- 
compensation. If the sun fail in his supply of heat to 
this region, more of its vapours are condensed, and heat is 
discharged from its latent store-houses in quantities just 
sufficient to keep the machine in the most perfect com- 
pensation. If, on the other hand, too much heat be 
found to accompany the rays of the sun as they impinge 
upon the upper circumference of this belt, then again on 
that side the means of self-compensation are ready at 
hand ; so much of the cloud-surface as may be requisite 
is then resolved into invisible vapour—for of invisible 
vapour are made the vessels wherein the surplus heat from 
the sun is stored away and held in the latent state until 
it is called for, when instantly it is set free, and becomes 
a palpable and active agent in the grand design. 

That the thermometer stands invariably lower'beneath 
this cloud-belt than it does on either side of it, has not, 
so far as my researches are concerned, been made _ to 
appear by actual observation, for the observations in my 
possession have not yet been fully discussed concerning 
the temperature of the air. But that the temperature of 
the air at the surface under this cloud-ring is lower, is a 
theoretical deduction as susceptible of demonstration as is 
the rotation of the earth on its axis. Indeed, Nature 
herself has hung a thermometer under this cloud-belt that 
is more perfect than any that man can construct, and its 
indications are not to be mistaken. 


591, 


CHAPTER 
xX. 


It affords 
self-com- 
pensation 
to the 
great at- 
mospheric 
machine. 


§ 601 


Nature has 
hung a 
thermom- 
eter under 
the cloud- 
belt. 


CHAPTER 
x 


§ 602 
Whence 
come the 
vapours 
forming 
this cloud- 
ring? 


§ 603 


Constant 
precipita- 
tion under 
it. 


260 THE PHYSICAL GEOGRAPHY OF THE SEA. 


Where do the vapours which form this cloud-ring, and 
which are here condensed and poured down into the sea 
as rain, come from? They come from the trade-wind 
regions ; under the cloud-ring they rise up; as they rise 
up they expand; and as they expand they grow cool, 
form clouds, and then are condensed into rains; more- 
over, it requires no mercurial instrument of human device 
to satisfy us that the air which brings the vapour for these 
clouds cannot take it up and let it down at the same 
temperature. Precipitation and evaporation are the con- 
verse of each other, and the same air cannot precipitate 
and evaporate, take up and let down water, at one and 
the same temperature. As the temperature of the air is 
raised, its capacity for receiving and retaining water in 
the state of vapour is increased ; as the temperature of the 
air is lessened, its capacity for retaining that moisture is 
diminished. These are physical laws, and_ therefore, 
when we see water dripping from the atmosphere, we 
need no instrument to tell us that the elasticity of the 
vapour so condensed, and falling in drops, is less than was 
its elasticity when it was taken up from the surface of 
the ocean as water, and went up into the clouds as 
vapour. 

Hence we infer, that when the vapours of sea water 
are condensed, the heat which was necessary to sustain 
them in the vapour state, and which was borrowed from 
the ocean, is parted with, and that therefore they were 
subjected, in the act of condensation, to a lower tempera- 
ture than they were in the act of evaporation. Ceaseless 
precipitation goes on under this cloud-ring. | Evaporation 
under it is suspended almost entirely. We know that 


THE EQUATORIAL CLOUD-RING. 261 


the trade-winds encircle the earth; that they blow per- 
petually ; that they come from the north and the south, 
and meet each other near the equator; therefore we in- 
fer that this line of meeting extends around the world. 
By the rainy seasons of the torrid zone, except where it 
may be broken by the continents, we can trace the de- 
clination of this cloud-ring, stretched like a girdle around 
our planet, up and down the earth; it travels up and 
down the ocean, as from north to south and back. 

It is broader than the belt of calms out of which it 
rises. As the air, with its vapours, rises up in this calm 
belt and ascends, these vapours are condensed into clouds} 
and this condensation is followed by a turgid intu- 
mescence, which causes the clouds to overflow the calm 
belt, as it were, both to the north and the south. The 
air flowing off in the same direction assumes the cha- 
racter of winds that form the upper currents that are 
counter (Plate I.) to the trade-winds. These currents 
carry the clouds still farther to the north and south, and 
thus make the cloud-ring broader ; at least we infer such 
to be the case, for the rains are found to extend out into 
the trade-winds, and often to a considerable distance both 
to the north and the south of the calm belt. 

Were this cloud-ring luminous, and could it be seen by 
an observer from one of the planets, it would present to 
him an appearance not unlike the rings of Saturn to 
us. Such an observer would remark that this cloud-ring 
of the earth has a motion contrary to that of the axis of 
our planet itself—that while the earth was revolving 
rapidly from west to east, he would observe the cloud- 
ring to go slowly, but only relatively, from east to west. 


-— 


1 § 602. 


CHAPTER 
X. 


The cloud- 
ring forms 
a girdle 
round the 
earth. 


§ 604 


Condenss 
tion. 


§ 605 


Supposed 
appear- 
ance of the 
cloud-ring 


SHAPTER 
x. 


its motion, 


$ 606 


$ 607 
Effect of 
sun rays 
on it. 


§ 608 


hunder. 


§ 609 


262 THE PHYSICAL GEOGRAPHY OF THE SEA. 


As the winds which bring this cloud- vapour to this region 
of calms rise up with it, the earth is slipping from under 
them; and thus the cloud-ring, thongh really moving 
from west to east with the earth, goes relatively slower 
than the earth, and would therefore appear to require a 
longer time to complete a revolution. 

But, unlike the rings of Saturn through the telescope, 
the outer surface, or the upper side to us, of this cloud- 
ring, would appear exceedingly jagged, rough, and un- 
even, 

The rays of the sun, playing upon this peak and then 
upon that of the upper cloud-surface, melt away one set 
of elevations, and create another set of depressions. The 
whole stratum is, it may be imagined, in the most turgid 
state ; it is in continued throes when viewed from above; 
the heait which is liberated from below in the process of 
condensation, the currents of warm air ascending from 
the earth, and of cool descending from the sky, all, we 
may well conceive, tend to keep the upper cloud-surface 
in a perpetual state of agitation, upheaval, and depression. 

Imagine in such a cloud-stratum an electrical discharge 
to take place; the report, being caught up by the cloud- 
ridges above, is passed from peak to peak, and repeated 
from valley to valley, until the last echo dies away in 
the mutterings of the distant thunder. How often do 
we hear the voice of the loud thunder rumbling and roll- 
ing away above the cloud-surface, like the echo of artillery 
discharged among the hills ! 

Hence we perceive or infer that the clouds intercept 
the progress of sound, as well as of light and heat, through 
the atmosphere, and that this upper surface is often like 


THE EQUATORIAL CLOUD-RING. 263 


Alpine regions, which echo back and roll along with 
rumbling noise the mutterings of the distant thunder. 

It is by trains of reasoning like this that we are con- 
tinually reminded of the interest which attaches to the 
observations which the mariner is called on to make. 
There is no expression uttered by nature which is un- 
worthy of our most attentive consideration —for no physi- 
eal fact is too bald for observation—and mariners, by 


registering in their logs the kind of Lghtning, whether 


S 
sheet, forked, or streaked, and the kind of thunder, 
whether rolling, muttering, or sharp, may be furnishing 
facts which will throw much light on the features and 
character of the clouds in different latitudes and seasons. 
Physical facts are the language of Nature, and every 
expression uttered by her is worthy of our most attentive 


consideration, for it is the voice of WISDOM. 


CHAPTEN 
xX. 


§ 610 
Import- 
ance of 
observing 
physica) 
facts. 


CHAPTER 
XI. 

§ 611 
How to 
regard 
nature. 


§ 612 


Connec- 
tion of geo- 
logy with 
naviga- 
tion, &c 


§ 613 


Astrono- 
my. 


264 THE PHYSICAL GEOGRAPHY OF THE SEA. 


CHAPTER XI. 


ON THE GEOLOGICAL AGENCY OF THE WINDS. 


Nature regarded as a Whole, § 611.—The Dead Sea, 614.—Annual fall of Rain 
upon, less now than formerly, 615.—The Caspian, 617.—The great American 
Lakes, 622.—Gulf of Mexico, its Depth, 624.—The Effect of cutting off the 
(culf Stream, 625.—U prising of Continents, 627.—The Causes that change the 
Water-level of a country, 633.—Foot-prints of the Clouds, 638.—Andes rising 
from the Sea, 640.—Rains for Europe, 651.—Terrestrial Adaptations, 655.— 
Kvaporating Force in the Mediterranean, 661.—Display of Harmony, 663.— 
The Age of the Andes and Dead Sea compared, 671, 

PROPERLY to appreciate the various offices which the 
winds and the waves perform, we must regard nature as 
a whole, for all the departments thereof are intimately 
connected. If we attempt to study in one of them, we 
often find ourselves tracing clews which lead us off insen- 
sibly into others, and, before we are aware, we discover 
ourselves exploring the chambers of some other depart- 
ment. 

The study of drift takes the geologist out to sea, and 
reminds him that a knowledge of waves, winds, and cur- 
rents, of navigation and hydrography, are closely and 
intimately connected with his favourite pursuit. 

The astronomer directs his telescope to the most remote 
star, or to the nearest planet in the sky, and makes an 
observation upon it. He cannot reduce this observation, 
nor make any use of it, until he has availed himself of 
certain principles of optics; until he has consulted the 
thermometer, gauged the atmosphere, and considered the 
effect of heat in changing its powers of refraction. In 
order to adjust the pendulum of his clock to the right 


; 


ON THE GEOLOGICAL AGENCY OF THE WINDS. ZOD 


length, he has to measure the water of the sea and weigh cnaprea 
the earth. He, too, must therefore go into the study of an 


Connec- 


the tides; he must examine the earth’s crust, and con- tion of one 
sider the matter of which it is composed, from pole to vin 
pole, circumference to centre: and in doing this, he finds ae 
himself, in his researches, right alongside of the navigator, 

the geologist, and the meteorologist, with a host of other 
good fellows, each one holding by the same thread, and 
following it up into the same labyrinth—all, it may be, 

with different objects in view, but nevertheless each thread 

will be sure to lead them where there are stores of know- 
ledge for all, and instruction for each one in particular. 

And thus, in undertaking to explore the physical geo- 
graphy of the sea, I have found myself standing side by 
side with the geologist on the land, and with him, far 
away from the sea-shore, engaged in considering some of 

the phenomena which the inland basins of the earth— 
those immense indentations on its surface that have no 

sea drainage—present for contemplation and study. 

Among the most interesting of these is that of the s 614 
Dead Sea. Lieutenant Lynch, of the United States Navy, ie Dexa 
has run a level from that sea to the Mediterranean, and 
finds the former to be about one thousand three hundred 
feet below the general sea-level of the earth. In seeking iperents 
to account for this great difference of water-level, the once 
geologist examines the neighbouring region, and calls to ranean. 
his aid the forces of elevation and depression which are 
supposed to have resided in the neighbourhood ; he then 
points to them as the agents which did the work. Truly causes 
they are mighty agents, and they have diversified the 
surface of the earth with the most towering monuments 


266 THE PHYSICAL GEOGRAPHY OF THE SEA. 


cnarter Of their power. But is it necessary to suppose that they 
XI. . . siewate . . 
resided in the vicinity of this region? May they not 
Author's : . . 
pai have come from the sea, and been, if not in this case, at 


tion. 


least in the case of other inland basins, as far removed as 
the other hemisphere? This is a question which I do not 
pretend to answer definitely. But the inquiry as to the 
geological agency of the winds in such cases is a question 
which my investigations have suggested. It has its seat 
in the sea, and therefore I propound it as one which, in 
accounting for the formation of this or that inland basin, 
is worthy, at least, of consideration. 

§615 Is there any evidence that the annual amount of pre- 
Wasthe ¢ipitation upon the water-shed of the Dead Sea, at some 


precipita- 


tion on it former period, was greater than the annual amount of 


greater at 


aformer evaporation from it now is? If yea, from what part of 

than now? the sea did the vapour that supplied the excess of that 
precipitation come, and what has cut off that supply ? 
The mere elevation of the rim and depression of the lake 
basin’ would not cut it off. 

§ 616 If we establish the fact that the Dead Sea at a former 
period did send a river to the ocean, we carry along with 
this fact the admission that when that sea overflowed into 
that river, then the water that fell from the clouds over 
the Dead Sea basin was more than the winds could con- 
vert into vapour and carry away again; the river carried 
off the excess to the ocean whence it came.’ 

¢ 617. In the basin of the Dead Sea, in the basin of the 

Precipitae Caspian, of the Sea of Aral, and in the other inland 


tion and 


evapora- basins of Asia, we are entitled to infer that the precipi- 


tion equal 


now. tation and evaporation are at this time exactly equal. 
Were it not so, the level of these seas would be rising or 


ON THE GEOLOGICAL AGENCY OF THE WINDS. 267 


sinking. If the precipitation were in excess, these seas 
would be gradually becoming fuller; and if the evapora- 
tion were in excess, they would be gradually drying up ; 
but observation does not show, nor history tell us, that 
either is the case. As far as we know, the level of these 
seas is as permanent as that of the ocean, and it is diffi- 
eult to realize the existence of subterranean channels 
between them and the great ocean. Were there such 
a channel, the Dead Sea being the lower, it would be the 
recipient of ocean waters; and we cannot conceive how 
it should be such a recipient without ultimately rising to 
the level of its feeder. 

It may be that the question suggested by my researches 
has no bearing upon the Dead Sea; that local elevations 
and subsidences alone were concerned in placing the level 
of its waters where it is. But is it probable that, through- 
out all the geological periods, during all the changes that 
have taken place in the distribution of land and water 
surface over the earth, the winds which, in the general 
channels of circulation, pass over the Dead Sea have 
alone been unchanged? Throughout all ages, periods, 
and formations, is it probable that the winds have brought 
just as much moisture to that sea as they now bring, 
and have just taken up as much water from it as they 
now carry off? Obviously and clearly not. The salt- 
beds, the water-marks, the geological formations, and 
other facts traced by Nature’s own hand upon the tab- 
lets of the rock, all indicate plainly enough that not 
only the Dead Sea, but the Caspian also, had upon them, 
in former periods, more abundant rains than they now 
have. Where did the vapour for those rains come from? 


CHAPTER 
XI. 


Proofs of 
this. 


§ 618 


Proba- 
bility that 
there were 
more 
abundant 
rains at a 
former 
period. 


Whence 
came the 
vapour for 
them ? 


CHAPTER 
XT. 


§ 619 
South- 
west trades 
the rain- 
winds for 
Europe. 


$ 620 


ae ors 
op 


268 THE PHYSICAL GEOGRAPHY OF THE SEA. 


and what has stopped the supply? Surely not the ele- 
vation or depression of the Dead Sea basin. 

My researches with regard to the winds have sug- 
gested the probability’ that the vapour which is condensed 
into rains for the lake valley, and which the St. Law- 
rence carries off to the Atlantic Ocean, is taken up by 
the south-east trade-winds of the Pacific Ocean. Suppose 
this to be the case, and that the winds which bring this 
vapour arrive with it in the lake country at a mean dew- 
point of 50°. This would make the south-west winds 
the rain winds for the lakes generally, as well as for 
the Mississippi Valley ; they are also, speaking generally, 
the rain winds of Europe, and, I have no doubt, of extra- 
tropical Asia also. 

Now, suppose a certain mountain range, hundreds of 
miles to the south-west of the lakes, but across the path 
of these winds, were to be suddenly elevated, and its 
crest pushed into the regions of snow, having a mean 
temperature at its summit of 30° Fahrenheit. The winds, 
in passing that range, would be subjected to a mean dew- 
point of 30°; and, not meeting” with any more evaporat- 
ing surface between such range and the lakes, they would 
have no longer any moisture to deposit at the supposed 
lake temperature of 50°; for they could not yield their 
moisture to anything above 30° Consequently, the 
amount of precipitation in the lake country would fall 
off; the winds which feed the lakes would cease to bring 
as much water as the lakes now give to the St. Law- 
rence. In such a case, that river and the Niagara would 
drain them to the level of their bed; evaporation would 
be increased by reason of the dryness of the atmosphere 


¥ § 172. 2 § 196. 


ON THE GEOLOGICAL AGENCY OF THE WINDS. 269 


and the want of rain, and the lakes would sink to that 
level at which, as in the case of the Caspian Sea, the 
precipitation and evaporation would finally become equal. 

There is a self-regulating principle that would bring 
about this equality ; for as the water in the lakes becomes 
lower, the area of its surface would be diminished, and 
the amount of vapour taken from it would consequently 
become less and less as the surface was lowered, until 
the amount of water evaporated would become equal to 
the amount rained down again, precisely in the same 
way that the amount of water evaporated from the sea 
is exactly equal to the whole amount poured back into it 
by the rains, the fogs, and the dews.* Thus the great 
lakes of this continent would remain inland seas at a 
permanent level; the salt brought from the soil by the 
washings of the rivers and rains would cease to be taken 
off to the ocean as it now is; and finally, too, the great 
American lakes, in the process of ages, would become 
first brackish, and then briny. 

Now, suppose the water-basins which hold the lakes 
to be over a thousand fathoms (six thousand feet) deep. 
We know they are not more than four hundred and twenty 
feet deep; but suppose them to be six thousand feet 
deep. The process of evaporation, after the St. Lawrence 
had gone dry, might go on until one or two thousand 
feet or more were lost from the surface; and we should 
then have another instance of the level of an inland 
water-basin being far below the sea-level, as in the case 
of the Dead Sea; or it would become a rainless district, 
when the lakes themselves would go dry. 


* ‘The quantity of dew in Ergland is about five inches Inring a year. —Glacsher. 


CHAPTER 
XI. 


$ 621 


Continued 


§ 622 


Tlustra- 
tion. 


270 THE PHYSICAL GEOGRAPHY OF THE SEA. 


cuspter Or let us take another case for illustration. Corallines 
Xi. 


§ 623 
Supposed 


obstrue- =the other. Suppose they should build up a dam across 
tion of the 


eo the Florida Pass, and obstruct the Gulf Stream ; and that, 


Stream. 


are at work about the Gulf Stream ; they have built up 
the Florida Reefs on one side, and the Bahama Banks on 


in like manner, they were to connect Cuba with Yucatan 
by damming up the Yucatan Pass, so that the waters of 
the Atlantic should cease to flow into the Gulf of Mexico. 
What should we have? 

§ 624 The depth of the marine basin which holds the waters 
of that Gulf is, in the deepest part, about three quarters 
of a mile. The officers of the United States ship Albany 
have run a line of deep-sea soundings from west to east 
across the Gulf; the greatest depth they reported was 
about six thousand feet. Subsequent experiments, how- 
ever, induce the belief that the depth is not quite so great. 

§ 625 We should therefore have, by stopping up the channels 

ue Bee between the Gulf and the Atlantic, not a sea level in the 
Gulf, but we should have a mean level between evapo- 
ration and precipitation. If the former were in excess, 
the level of the Gulf waters would sink down until the 
surface exposed to the air would be just sufficient to 
return to the atmosphere, as vapour, the amount of water 
discharged by the rivers, the Mississippi and others, 
into the Gulf As the waters were lowered, the extent 
of evaporating surface would grow less and less, until 
Nature should establish the proper ratio between the 
ability of the air to take up and the capacity of the 
clouds to let down. Thus we might have a sea whose 
ievel would be much farther below the water-level of the 
ocean than is the Dead Sea. 


ON THE GEOLOGICAL AGENCY OF THE WINDS. 27] 


There is still another process, besides the two already cuavrex 
alluded to, by which the drainage of these inland basins cas 


may, through the agency of the winds, have been cut off ea 
from the great salt seas; and that is by the elevation of Pires Ps 


which in- 


continents from the bottom of the sea in distant regions nd basi 


of the earth, and the substitution caused thereby of dry benoit 

land instead of water for the winds to blow upon. the seus. 
Now suppose that a continent should rise up in that § 627 

part of the ocean, wherever it may be, that supplies the Supposed 


result of a 


clouds with the vapour that makes the rain for the continent 
hydrographic basin of the great American lakes. What in the 
would be the result? Why, surely, fewer clouds and less ie 
rain, which would involve a change of climate in the lake 
country ; an increase of evaporation from it, because a 
decrease of precipitation upon it; and consequently, a 
diminution of cloudy screens to protect the waters of the 

lakes from being sucked up by the rays of the sun ; and 
consequently, too, there would follow a low stage for 
water-courses, and a lowering of the lake-level would 
ensue. 

So far, I have instanced these cases only hypothetically; § 628 
but, both in regard to the hydrographical basins of the 
Mexican Gulf and American lakes, I have confined myself 
strictly to analogies. Mountain ranges have been up- 
heaved across the course of the winds, and continents 
have been raised from the bottom of the sea; and, no 
doubt, the influence of such upheavals has been felt in 
remote regions by means of the winds, and the effects 
which a greater or less amount of moisture brought by 
them would produce. 


In the case of the Salt Lake of Utah we have an § 629 


cHAPTER 
xI. 


Salt lake of 
Utah an 
illustra- 
tion of how 
nature 
equalizes 
evapora- 
tion and 
precipita- 
ton. 


Former 
connection 
between 
the great 
American 
lakes and 
the Gulf of 
Mexico. 


§ 630 


Y 


72 THE PHYSICAL GEOGRAPHY OF THE SEA. 


i 


example of drainage that has been cut off, and an illustra- 
tion of the process by which Nature equalizes the eva 
poration and precipitation. To do this, in this instance, 
she is salting up the basin which received the drainage 
of this inland water-shed. Here we have the appearance, 
I am told, of an old channel by which the water used to 
flow from this basin to the sea. Supposing there was 
such a time and such a water-course, the water returned 
through it to the ocean was the amount by which the 
precipitation used to exceed the evaporation over the 
whole extent of country drained through this now dry 
bed of a river. The winds have had something to do 
with this; they are the agents which used to bring more 
moisture from the sea to this water-shed than they carried 
away ; and they are the agents which now carry off from 
that valley more moisture than is brought to it, and 
which, therefore, are making a salt-bed of places that used 
to be covered by water. In like manner, there is evidence 
that the great American lakes formerly had a drainage 
with the Gulf of Mexico, for boats or canoes have been 
actually known, in former years, and in times of freshets, 
to pass from the Mississippi River over into the lakes. 
At low water, the bed of a dry river can be traced between 
them. Now the Salt Lake of Utah is to the southward 
and westward of our northern lake basin; that is the 
quarter’ whence the rain-winds have been supposed to 
come. May not the same cause which lessened the 
precipitation, or increased the evaporation in the Salt 
Lake water-shed, have done the same for the water-shed 
of the great American system of lakes ? 

If the mountains to the west—the Sierra Nevada, for 


~ 
un 


ON THE GEOLOGICAL AGENCY OF THE WINDS. 273 


instance—stand higher now than they formerly did; and 


if the winds which fed the Salt Lake valley with precipi- 


tation had, as’ I suppose they have, to pass the summits 
of the mountains ; it is easy to perceive why the winds 
should not convey as much vapour across them now as 
they did when the summit of the range was lower and 
not so cool. 

The Andes, in the trade-wind region of South America, 
stand up so high, that the wind, in order to cross them, has 
to part with all its moisture ;*and consequently there is, on 
the west side, a rainless region. Now, suppose a range of 
such mountains as these to be elevated across the track of 
the winds which supply the lake country with rains ; it is 
easy to perceive how the whole country to the leeward 
of such range, and now watered by the vapour which 
such winds bring, would be converted into a rainless 
region. 

I have used these hypothetical cases to illustrate a 
position which any philosopher, who considers the geo- 
logical agency of the winds, may with propriety consult, 
when he is told of an inland basin, the water-level of 
which, it is evident, was once higher than it now is ; and 
that position is, that, though the evidences of a higher 
water-level be unmistakable and conclusive, it does not 
follow, therefore, that there has been a subsidence of the 
lake basin itself, or an upheaval of the water-shed drained 
by it. 

The cause which has produced this change in the water- 
level, instead of being local and near, may be remote ; 
it may have its seat in the obstructions to “the wind in 
his circuits,” which have been interposed in some other 


2 § 361. 2 § 196. 
18 


CHAPTER 
XI. 
How 
mountains 
intercept 
the winds. 


§ 631 
The Andes 


§ 632 
Position 
which may 
be con- 
sulted 
when an 
inland 
basin 
shows a 
former 
high level 


§ 633 
The cause 
of the 
change 
may be re- 
mote, 


CHAPTER 


§ 634 


Has the 
elevation 
of the 
South 
American 
continent 
any effect 
on the 
level of the 
Dead Sea 
and Cas- 
pian ? 


They once 
had a 
higher 
level. 


§ 635 


Evidence 
contained 
in previous 
chapters. 


274 THE PHYSICAL GEOGRAPHY OF THE SEA. 


quarter of the world; which obstructions may prevent the 
winds from taking up, or from bearing off, their wonted 
supplies of moisture for the region whose water-level has 
been lowered. 

Having therefore, I hope, made clear the meaning of 
the question proposed, by showing the manner in which 
winds may become important geological agents; and 
having explained how the upheaving of a mountain range 
in one part of the world may, through the winds, bear 
upon the physical geography of the sea, affect climates, 
and produce geological phenomena in another; I return 
to the Dead Sea and the great inland basins of Asia, and 
ask, How far is it possible for the elevation of the South 
American continent, and the upheaval of its mountains, 
to have had any effect upon the water-level of those seas? 
There are indications’ that they all once had a higher 
water-level than they now have, and that formerly the 
amount of precipitation was greater than it now is; then 
what has become of the sources of vapour? what has 
diminished its supply? Its supply would be diminished” 
either by the substitution of dry land for water-surface 
in those parts of the ocean which used to supply that 
vapour ; or the quantity of vapour deposited in the hydro- 
graphical basins of those seas would have been lessened if 
a snow-capped range of mountains® had been elevated 
across the path of these winds, between the places where 
they were supplied with vapour and these basins. 

A chain of evidence which it would be difficult to set 
aside is contained in the chapters beginning severally at 
p. 62, 135, and 249, going to show that the vapour 
which supplies the extra-tropical regions of the north 


1 § 618. 2 $627, * § 620. 


ON THE GEOLOGICAL AGENCY OF THE WINDS. 275 


with rains comes, in all probability, from the trade-wind cxarres 
regions of the southern hemisphere. ae 
Now, if it be true that the trade-winds from that part § 636 
of the world take up there the water which is to be Cos: of 
rained in the extra-tropical north, the path ascribed to »inas. 
the south-east trades of Africa and America, after they 
descend and become the prevailing south-west winds of 
the northern hemisphere, should pass over a region of 
less precipitation generally than they would do if, while 
performing the office of south-east trades, they had blown 
over water instead of land. The south-east trade-winds, 
with their load of vapour, whether great or small, take, 
after ascending in the equatorial calms, a north-easterly 
direction ; they continue to flow in the upper regions of 
the air in that direction until they cross the tropic of 
Cancer. The places of least rain, then, between this Theory. 
tropic and the pole, should be precisely those places — 
which depend for their rains upon the vapour which the 
winds that blow over south-east trade-wind Africa and 
America convey. 
Now, if we could trace the path of the winds through § 637 
the extra-tropical regions of the northern hemisphere, we peeks 


hese 


should be able to identify the track of these Andean ves 
winds by the foot-prints of the clouds; for the path of 

the winds which depend for their moisture upon such 
sources of supply as the dry land of Central South Ame- 

rica and Africa cannot lie through a country that is 
watered well. 

It is a remarkable coincidence, at least, that the coun- § 638 

tries in the extra-tropical regions of the north that are Remars- 


able coin- 


situated to the north-east of the south-east trade-winds ‘idence 


confirming 
theory. 


CHAPTER 
xI. 


“Lee 
country.” 


$ 639 
Its supply 
of mois- 
ture. 


$ 640 


The Andes 
once co- 
vered by 
the sea. 


276 THE PHYSICAL GEOGRAPHY OF THE SEA. 


of South Africa and America—that these countries, over 
which theory makes these winds to blow, include all the 
great deserts of Asia, and the districts of least precipita- 
tion in Europe. <A line from the Galapagos Islands 
through Florence in Italy, another from the mouth of 
the Amazon through Aleppo in the Holy Land (Plate VIJ), 
would, after passing the tropic of Cancer, mark upon the 
surface of the earth the route of these winds; this is 
that “lee country” which, if such be the system of 
atmospherical circulation, ought to be scantily supplied 
with rains. Now, the hyetographic map of Europe, in 
Johnston’s beautiful Physical Atlas, places the region of 
least precipitation between these two lines. (Plate VIL) 

It would seem that nature, as if to reclaim this “lee” 
land from the desert, had stationed by the wayside of 
these winds a succession of inland seas, to serve them 
as relays for supplying them with moisture. There is 
the Mediterranean, with its arms, the Caspian Sea, and 
the Sea of Aral, all of which are situated exactly in 
this direction, as though these sheets of water were 
designed, in the grand system of aqueous arrangements, 
to supply with fresh vapour, winds that had already left 
rain enough behind them to make an Amazon and an 
Oronoco of. 

Now, that there has been such an elevation of land 
out of the water, we infer from the fact that the Andes 
were once covered by the sea, for their tops are now 
crowned with the remains of marine animals. When 
they and their continent were submerged—admitting 
that Europe in general outline was then as it now is— 
it cannot be supposed, if the circulation of vapour were 


1 ¢ 200, 


ON THE GEOLOGICAL AGENCY OF THE WINDS. 270 


then such as it is suppused now to be, that the climates 
ef that part of the Old World which is under the lee 
of those mountains were then as scantily supplied with 
moisture as they now are. When the sea covered South 
America, the winds had nearly all the waters which now 
make the Amazon to bring away with them, and to dis- 
tribute among the countries situated along the route 
(Plate VII.) ascribed to them. 

If ever the Caspian Sea exposed a larger surface for 
and no doubt it did; if 
the precipitation in that valley ever exceeded the evapo- 


evaporation than it now does 


ration from it, as it does in all valleys drained into the 
open sea; then there must have been a change of hygro- 
metrical conditions there. And admitting the vapour 
springs for that valley to be situated in the direction 
supposed, the rising up of a continent from the bottom 
of the sea, or the upheaval of a range of mountains in 
certain parts of America, Africa, or Spain, across the 
route of the winds which brought the rain for the Cas- 
pian water-shed, might have been sufficient to rob them 
of the moisture which they were wont to carry away 
and precipitate upon this great inland basin. See how 
the Andes have made Atacama a desert, and of Western 
Peru a rainless country ; these regions have been made 
rainless simply by the rising up of a mountain range 
between them and the vapour springs in the ocean which 
feed with moisture the winds that blow over those now 
rainless regions. 


CHAPTER 
XT. 


Supposed 
effect of 
this on the 
countries 
now scan- 
tily sup- 
plied with 
water. 


$ 641 


Change in 
the valley 
of the Cas- 
pian Sea. 


Climate 
modified 
by moun- 
tain 
ranges. 


Tustance. 


That part of Asia, then, which is under the lee of $ 642 


southern trade-wind Africa, lies to the north of the tropic 


Lines re- 
presenting 


of Cancer, and between two lines, the one passing ue 
ry.” 


CHAPTER 


§ 643 


Reference 
to Plate IL 


$ 644 


278 THE PHYSICAL GEOGRAPHY OF THE SEA. 


through Cape Palmas and Medina, the other through 
Aden and Delhi. Being extended to the equator, they 
will include that part of it which is crossed by the conti- 
nental south-east trade winds of Africa, after they have 
traversed the greatest extent of land surface. (Plate VII.) 

The range which lies between the two lines that repre- 
sent the course of the American winds with their vapours, 
and the two lines which represent the course of the 
African winds with their vapours, is the range which is 
under the lee of winds that have, for the most part, tra- 
versed water surface, or the ocean, in their circuit as 
south-east trade-winds. Buta bare inspection of Plate VII. 
will show that the south-east trade-winds which cross the 
equator between longitude 15° and 50° west, and which 
are supposed to blow over into this hemisphere between 
these two ranges, have traversed land as well as water ; 
and the Trade-wind Chart* shows that it is precisely 
those winds which, in summer and autumn, are converted 
into south-west monsoons for supplying the whole extent 
of Guinea with rains to make rivers of. Those winds, 
therefore, it would seem, leave much of their moisture 
behind them, and pass along to their channels in the 
grand system of circulation, for the most part, as dry 
winds. Moreover, it is not to be supposed that the chan- 
nels through which the winds blow that cross the equator 
at the several places named are as sharply defined in 
nature as the lines suggested, or as Plate VII. would repre- 
sent them to be. 

The whole region of the extra-tropical Old World that 
is included within the ranges marked, is the region which 


* Series of Maury’s Wind and Current Charts. 


ON THE GEOLOGICAL AGENCY OF THE WINDS. 279 


has most land to windward of it in the southern hemis- 
phere. Now it is a curious coincidence, at least, that all 
the great extra-tropical deserts of the earth, with those 
regions in Europe and Asia which have the least amount 
of precipitation upon them, should lie within this range. 
That they are situated under the lee of the southern con- 
tinents, and have but little rain, may be a coincidence, I 
admit ; but that these deserts of the Old World are placed 
where they are is no coincidence—no accident: they are 
placed where they are, and as they are, by design ; and 
in being so placed, it was intended that they should sub- 
serve some grand purpose in the terrestrial economy. 
Let us see, therefore, if we can discover any other marks 
of that design 


any of the purposes to be subserved by 
such an arrangement—and trace any connection between 
that arrangement and the supposition which I maintain 
as to the place where the winds that blow over these re- 
gions derive their vapours. 

It will be remarked at once that all the inland seas of 
Asia, and all those of Europe except the semi-fresh-water 
gulfs of the north, are within this range. The Persian 
Gulf and the Red Sea, the Mediterranean, the Black, 
and the Caspian, all fall within it. And why are they 
planted there? Why are they arranged to the north- 
east and south-west under this lee, and in the very 
direction in which theory makes this breadth of thirsty 
winds to prevail? Clearly and obviously, one of the 
purposes in the divine economy was, that they might re- 
plenish with vapour the winds which are almost vapour- 
less when they arrive at these regions in the general sys- 
tem of circulation. And why should these winds Le 


CHAPTER 
XI. 


Curious co 
incidence. 


Design in 
situation 
of the 
deserts. 


Endeavour 
to trace it. 


§ 645 
Arrance- 
ment of 
the inland 
seas, 


Their use. 


CEAPTER 
XI. 


§ 646 


Mediter- 
ranean 
and Red 
Sea. 


Winds 
which 
blow over 
them come 
from a dry 
country. 


$ 647 


Evapora- 
tion ex- 
ceeds pre- 
cipitation 
in the 
Mediter- 
ranean. 


280 THE PHYSICAL GEOGRAPHY OF THE SEA. 


almost vapourless? They are almost vapourless because 
their route, in the general system of circulation, is such, 
that they are not brought into contact with a water- 
surface from which the needful supplies of vapour are to 
be had; or, being obtained, the supplies have since been 
taken away by the cool tops of mountain ranges over 
which these winds have had to pass. 

In the Mediterranean, the evaporation is greater than 
the precipitation. Upon the Red Sea there never falls a 
drop of rain; it is all evaporation. Are we not, there- 
fore, entitled to regard the Red Sea as a make-weight, 
thrown in to regulate the proportion of cloud and sun- 
shine, and to dispense rain to certain parts of the earth 
in due season and in proper quantities? Have we not, 
in these two facts, evidence conclusive that the winds 
which blow over these two seas come, for the most part, 
from a dry country—from regions which contain few 
or no pools to furnish supplies of vapour ? 

Indeed, so scantily supplied with vapour are the winds 
which pass in the general channels of circulation over the 
water-shed and sea-basin of the Mediterranean, that they 
take up there more water as vapour than they deposit. 
But, throwing out of the question what is taken up from 
the surface of the Mediterranean itself, these winds de- 
posit more water on the water-shed whose drainage leads 
into that sea than they take up from it again. The ex- 
cess is to be found in the rivers which discharge them- 
selves into the Mediterranean; but so thirsty are the 
winds which blow across the bosom of that sea, that they 
not only take up again all the water that those rivers 
pour into it, but they are supposed by philosophers to 


ON THE GEOLOGICAL AGENCY OF THE WINDS. 281 


create a demand for an immense current from the Atlantic cmspres 
to supply the waste. ae 

It is estimated that three* times as much water as the § 648 
Mediterranean receives from its rivers 1s evaporated from Estimate 
its surface. This may be an over-estimate, but the fact 
that evaporation from it is in excess of the precipitation, 
is made obvious by the current which the Atlantic sends 
into it through the Straits of Gibraltar ; and the differ- 
ence, we may rest assured, whether it be much or little, 
is carried off to modify climate elsewhere—to refresh 
with showers and make fruitful some other parts of the 
earth. 

The great inland basin of Asia, in which are Aral and § 649 
the Caspian Seas, is situated on the route which this # an 
hypothesis requires these thirsty winds from south-east Pi” Seas 
trade-wind Africa and America to take: and so scant of 
vapour are these winds when they arrive in this basin, 
that they have no moisture to leave behind ; just as much 
as they pour down they take up again and carry off. We 
know'that the volume of water returned by the rivers, 
the rains, and the dews, into the whole ocean, is exactly 
equal to the volume which the whole ocean gives back to 
the atmosphere. As far as our knowledge extends, the 
level of each of these two seas is as permanent as that of 
the great ocean itself; therefore, the volume of water 
discharged by rivers, the rains, and the dews, into these 
two seas, is exactly equal to the volume which these two 
seas give back as vapour to the atmosphere. 

These winds, therefore, do not begin permanently to § 650 
lay down their load of moisture, be it great or small, 


* Vide article “ Physical Geography,” Encyclopedia Britannica. 
18166 
§ 1be, 


no 


82 THE PHYSICAL GEOGRAPHY OF THE SEA. 


cnEEIER until they cross the Oural Mountains. On the steppes of 


am Issam, after they have supplied the Amazon and the other 

winds great equatorial rivers of the south, we find them first 

hind them beginning to lay down more moisture than they take up 

es again. In the Obi, the Yenesi, and the Lena, is to be 

a **° found the volume which contains the expression for the 
load of water which these winds have brought from the 
southern hemisphere, from the Mediterranean and the 
Red Sea; for in these almost hyperborean river-basins do 
we find the first instance in which, throughout the entire 
range assigned these winds, they have, after supplying 
the Amazon, &c., left more water behind them than they 
have taken up again and carried off. The low tempera- 
tures of Siberian Asia are quite sufficient to extract from 
these winds the remnants of vapour which the cool moun- 
tain-tops and mighty rivers of the southern hemisphere 
have left in them. 


§651 Here I may be permitted to pause, that I may call 
Perfec 
saat of 
eae the marks of design, the beautiful and exquisite adjust- 


andatmos- ments that we see here provided, to insure the perfect 


pherical 


machine. working of the great aqueous and atmospherical ma- 


attention to another remarkable coincidence, and admire 


chine. This coincidence—may I not call it cause and 
effect 7—is between the hygrometrical conditions of all 
the countries within, and the hygrometrical conditions of 
all the countries without, the range included within the 
lines which I have drawn (Plate VIL.) to represent the 
route in the northern hemisphere of the south-east trade- 
winds, after they have blown their course over the land 
in South Africa and America. Both to the right and 
left of this range are countries included between the same 


ON THE GEOLOGICAL AGENCY OF THE WINDS. 283 


parallels in which it is, yet these countries all receive 
more water from the atmosphere than they give back to 
it again,—they all have river srunning into the sea. On 
the one hand, there is in Europe the Rhine, the Elbe, 
and all the great rivers that empty into the Atlantic; on 
the other hand, there are in Asia the Ganges, and all the 
great rivers of China; and in North America, in the 
latitude of the Caspian Sea, is our great system of fresh- 
water lakes: all of these receive from the atmosphere 
immense volumes of water, and pour it back into the sea 
in streams the most magnificent. 

It is remarkable that none of these copiously-supplied 
water-sheds have to the south-west of them, in the trade- 
wind regions of the southern hemisphere, any considerable 


CHAPTER 
xXxI. 


§ 652 


Remark- 
able fact in 
regard to 
the water- 


body of land; they are, all of them, under the lee of sheds 


evaporating surfaces, of ocean waters in the trade-wind 
regions of the south. Only those countries in the extra- 
tropical north, which I have described as lying under the 
lee of trade-wind South America and Africa, are scantily 
supplied with rains. Pray examine Plate VII. in this 
connection. It tends to confirm the views taken in 
Chapter VI. 

The surface of the Caspian Sea is about equal to that 
of our lakes; in it, evaporation is just equal to the pre- 
cipitation. Our lakes are between the same parallels, 


g ro 

S 653 
Compari- 
son be- 
tween Cas- 
pian Sea 


and about the same distance from the western coast of andCana- 


America that the Caspian Sea is from the western coast 
of Europe; and yet the waters discharged by the St. 
Lawrence give us an idea of how greatly the precipitation 
upon it is in excess of the evaporation, To windward 
of the lakes, and in the trade-wind regions of the southern 


dian lakes 


CHAPTER 
XI. 


§ 654 


New Hol- 
land and 
South 
Africa. 


§ 655 


Evidence 
of design. 


284 THE PHYSICAL GEOGRAPHY OF THE SEA. 


hemisphere, is no land; but to windward of the Caspian 
Sea, and in the trade-wind region of the southern hemi- 
sphere, there is land. Therefore, supposing the course of 
the vapour-distributing winds to be such as I maintain 
it to be, ought they not to carry more water from 
the ocean to the American lakes than it is possible for 
them to carry from the land—from the interior of 
South Africa and America 
Sea ? 


In like manner, extra-tropical New Holland and South 


to the valley of the Caspian 


Africa have each land—not water—to the windward of 
them in the trade-wind regions of the northern hemi- 
sphere, where, according to this hypothesis, the vapour 
for their rains ought to be taken up. They are both 
countries of little rain. But extra-tropical South America 
has, in the trade-wind region to windward of it in the 
northern hemisphere, a great extent of ocean, and the 
amount of precipitation” in extra-tropical South America 
is wonderful. The coincidence, therefore, is remarkable, 
that the countries in the extra-tropical regions of this 
hemisphere, which le to the north-east of large districts 
of land in the trade-wind regions of the other hemisphere, 
should be scantily supplied with rains; and likewise, 
that those so situated in the extra-tropical south, with 
regard to land in the trade-wind region of the north, 
should be scantily supplied with rains. 

Having thus remarked upon the coincidence, let us 
turn to the evidences of design, and contemplate the 
beautiful harmony displayed in the arrangement of the 
land and water, as we find them along this conjectural 
“ wind-road.” (Plate VIL.) 


1 § 393. a § 205 


ON THE GEOLOGICAL AGENCY OF THE WINDS. 285 


Those who admit design among terrestrial adaptations, 
or have studied the economy of cosmical arrangements, 
will not be loth to grant that by design the atmosphere 
keeps in circulation a certain amount of moisture, that 
the water of which this moisture is made is supplied by 
the aqueous surface of the earth, and that it is to be 
returned to the seas again through rivers and the pro- 
cess of precipitation ; for, were it not so, there would be 
a permanent increase or decrease of the quantity of water 
thus put and kept in circulation by the winds, which 
would be followed by a corresponding change of hygro- 
metrical conditions, which, in turn, would draw after it 
permanent changes of climate; and permanent changes 
of climate would involve the ultimate well-being of 
myriads of organisms, both in the vegetable and animal 
kingdoms. 

The quantity of moisture that the atmosphere keeps 
in circulation is, no doubt, just that quantity which is 
best suited to the well-being, and most adapted to the 
proper development of, the vegetable and amimal king- 
doms ; and that quantity is dependent upon the arrange- 
ment and the proportions that we see in nature between 
the land and the water—between mountain and desert, 
river and sea. If the seas and evaporating surfaces were 
changed, and removed from the places they occupy to 
other places, the principal places of precipitation probably 
would also be changed; whole families of plants would 
wither and die for want of cloud and sunshine, dry and 
wet, in proper proportions and in due season ; and, with 
the blight of plants, whole tribes of animals would also 
perish. Under such a chance arrangement, man would 


CHAPTER 
XI. 

$ 656 

Design in 

the circu- 

lation of 

moisture. 


§ 657 
Quantity 
ofmoisture 
kept in cir- 
culation. 


CHAPTER 
xI, 


—- 


§ 658 


South-east 
trade- 
winds 
overleap 
the north- 
east trade- 
winds, 


§ 659 


The Tigris. 


286 THE PHYSICAL GEOGRAPHY OF THE SEA. 


no longer be able to rely upon the early and the latter 
rain, or to count with certainty upon the rains being 
sent in due season for seed-time and harvest. And that 
the rain will be sent in due season, we are assured from 
on high ; and when we recollect who it is that “ sendeth ” 
it, we feel the conviction strong within us, that He that 
sendeth the rain has the winds for his messengers ; and, 
that they may do his bidding, the land and the sea were 
arranged, both as to position and relative proportions, 
where they are, and as they are. 

It should be borne in mind that by this hypothesis, 
the south-east trade-winds, after they rise up at the equa- 
tor (Plate I.), have to overleap the north-east trade-winds. 
Consequently, they do not touch the earth until near 
the tropic of Cancer (see the bearded arrows, Plate VII.), 
more frequently to the north than to the south of it; but 
for a part of every year, the place where these vaulting 
south-east trades first strike the earth, after leaving the 
other hemisphere, is very near this tropic. On the equa- 
torial side of it, be it remembered, the north-east trade- 
winds blow; on the Polar side, what were the south-east 
trades, and what are now the prevailing south-westerly — 
winds of our hemisphere, prevail. Now examine Plate 
VIT.,and it will be seen that the upper half of the Red Sea 
is north of the tropic of Cancer; the lower half is to the 
south of it ; that the latter is within the north-east trade- 
wind region ; the former, in the region where the south- 
west passage winds are the prevailing winds. 

The River Tigris is probably evaporated from the upper 
half of this sea by these winds ; while the north-east trade- 
winds take up from the lower half those vapours which 


ON THE GEOLOGICAL AGENCY OF THE WINDS. 287 


feed the Nile with rain, and which the clouds deliver to cuaprer 
the cold demands of the Mountains of the Moon. Thus —— 
there are two “wind-roads” crossing this sea: to the Lees 
windward of it, each road runs through a rainless region; roads.” 
to the leeward there is, in each case, a river rained 

down. 

The Persian Gulf les, for the most part, in the track § 660 
of the south-west winds ; to the windward of the Persian F°"*" 
Gulf is a desert; to the leeward, the River Indus. This Pe¢ Ses 
is the route by which theory would require the vapour 
from the Red Sea and Persian Gulf to be conveyed, and 
this is the direction in which we find indications that it 
is conveyed. For to leeward do we find, in each case, 

a river, telling to us by signs not to be mistaken, that it 
receives more water from the clouds than it gives back to 
the winds. 

Is it not a curious circumstance, that the winds which § 661 
travel the road suggested from the southern hemisphere, $7" 
should, when they touch the earth on the Polar side of ‘°° 
the tropic of Cancer, be so thirsty, more thirsty, much 
more than those which travel on either side of their path, 
and which are supposed to have come from southern seas, 
not from southern lands ? 


The Mediterranean has to give those winds three § 662 


. . . 1 ° 

times as much vapour as it receives from them; the Nee ae 
Red Sea gives them as much as they can take, and received 
ck by 


receives nothing back in return but a iittle dew * the us 
Persian Gulf also gives more than it receives. What 
becomes of the rest? Doubtless it is given to the winds, 

that they may bear it off to distant regions, and make 


lands fruitful, that, but for these sources of supply, 


1 § 648. 2 § 407, 


CHAPTEX 
XI. 


§ 663 
Counter- 
poises in 
the hygro- 
metrical 
machinery 
of the 
earth. 


§ 664 


Harmony 
in earth, 
sea, and 
sky 


§ 665 


Exquisite 
adjust- 
ment of 
Caspian 
Sea. 


288 THE PHYSICAL GEOGRAPHY OF THE SEA. 


would be almost rainless, if not entirely arid, waste, and 
barren. 

These seas and arms of the ocean now present them- 
selves to the mind as counterpoises in the great hygro- 
metrical machinery of our planet ;—as sheets of water, 
placed where they are to balance the land in the trade- 
wind region of South America and South Africa, they 
now present themselves. When the foundations of the 
earth were laid, we know who it was that ‘“ measured 
the waters in the hollow of his hand, and meted out the 
heavens with a span, and comprehended the dust of the 
earth in a measure, and weighed the mountains in scales, 
and the hills in a balance ;’ and hence we know also 
that they are arranged both according to proportion and 
to place. 

Here, then, we see harmony in the winds, design in 
the mountains, order in the sea, arrangement in the dust, 
and form for the desert. Here are signs of beauty and 
works of grandeur; and we may now fancy that, in this 
exquisite system of adaptations and compensations, we 
ean almost behold in the Red and Mediterranean Seas, 
the very waters that were held in the hollow of the 
Almighty hand when he weighed the Andes, and balanced 
the hills of Africa in the comprehensive scales. 

In that great inland basin of Asia which holds the 
Caspian Sea, and embraces an area of one million and a 
half of geographical square miles, we see the water- 
surface so exquisitely adjusted that it is just sufficient, 
and no more, to return to the atmosphere as vapour 
exactly as much moisture as the atmosphere lends in rain 
to the rivers of that basin; a beautiful illustration of the 


ON THE GEOLOGICAL AGENCY OF THE WINDS. 289 


fact that the span of the heavens was meted out according 
to the measure of the waters. 

Thus we are entitled to regard’the Mediterranean, the 
Red Sea, and Persian Gulf, as relays, distributed along the 
route of these thirsty winds from the continents of the 
other hemisphere, to supply them with vapours, or to 
restore to them that which they have left behind to feed 
the sources of the Amazon, the Niger, and the Congo, 

The hypothesis that the winds from South Africa and 
America do take the course through Europe and Asia 
which I have marked out for them (Plate VIT.), is supported 
by so many coincidences, to say the least, that we are 
entitled to regard it as probably correct, until a train of 
coincidences, at least as striking, can be adduced to show 
that such is not the case. 

Returning once more to a consideration of the geological 
agency of the winds in accounting for the depression of 
the Dead Sea, we now see the fact palpably brought out 
before us, that if the Straits of Gibraltar were to be barred 
up, so that no water could pass through them, we should 
have a great depression of water-level in the Mediterranean, 
Three times as much water’ is evaporated from that sea 
as is returned to it through the rivers. <A portion of 
water evaporated from it is probably rained down and 
returned to it through the rivers; but, supposing it to 
be barred up, as the demand upon it for vapour would 
exceed the supply by rains and rivers, it would commence 
to dry up; as it sinks down, the area exposed for eva- 
poration would decrease, and the supplies to the rivers 
diminish, until, finally, there would be established between 
the evaporation and precipitation an equilibrium, as in 


2 § 639, - 2 § 648, 


CHAPTER 
XI. 


$ 666 
Offices of 
the Medi- 
terranean 
Sea, &c. 


§ 667 


Course of 
winds. 


§ 668 


Geological 
agency of 
winds on 
Dead Sea, 
«ec. 


Mediter- 
ranean. 


CHAPTER 


§ 669 


Lake Tad- an equilibrium, There are connected with it the remains 


jura. 


§ 670 
Winds are 
geological 
agents. 


§ 671 
Winds not 
a type of 
instability. 


§ 672 


290 THE PHYSICAL GEOGRAPHY OF THE SEA. 


the Dead and Caspian Seas. But, for aught we know, 
the water-level of the Mediterranean might, before this 
equilibrium were attained, have to reach a stage far below 
that of the Dead Sea level. 


The Lake Tadjura is now in the act of attaining such 


of a channel by which the water ran into the sea; but 
the surface of the lake is now five hundred feet below 
the sea-level, and it is salting up. If not in the Dead 
Sea, do we not, in the valley of this lake, find outcrop- 
ping some reason for the question, What have the winds 
had to do with the phenomena before us. 

The winds, in this sense, are geological agents of great 
power. It is not impossible but that they may afford us 
the means of comparing directly geological events which 
have taken place in one hemisphere, with geological 
events in another: e.g., the tops of the Andes were once 
at the hottom of the sea. Which is the oldest formation, 
that of the Dead Sea or the Andes? If the former be 
the older, then the climate of the Dead Sea must have 
been hygrometrically very different from what it now is. 

In regarding the winds as geological agents, we can 
no longer consider them as the type of instability. We 
should rather treat them in the light of ancient and 
faithful chroniclers, which, upon being rightly consulted, 
will reveal to us truths that Nature has written upon 
their wings in characters as legible and enduring as any 
with which she has ever engraved the history of geologi- 
cal events upon the tablet of the rock. 

The waters of Lake Titicaca, which receives the drain- 
age of the great inland basin of the Andes, are only 


ON THE GEOLOGICAL AGENCY OF THE WINDS. 291 


brackish, not salt. Hence we may infer that this lake 
has not been standing long enough to become briny, like 
the waters of the Dead Sea; consequently, it belongs to 
a more recent period. On the other hand, it will also be 
interesting to hear that my friend, Captain Lynch, informs 
me that, in his exploration of the Dead Sea, he saw what 
he took to be the dry bed of a river that once flowed from 
it. And thus we have two more links, stout and strong, 
to add to the chain of circumstantial evidence going to 
sustain the testimony of this strange and fickle witness 
which I have called up from the sea to testify in this 
presence concerning the works of Nature, and to tell us 
which be the older—the Andes, watching the stars with 
their hoary heads, or the Dead Sea, sleeping upon its an- 
cient beds of crystal salt. 


CHAPTER 
xI. 


Lake Titi- 
caca. 


nw 
ice) 
bo 


THE PHYSICAL GEOGRAPHY OF THE SEA. 


CHAPTER XII. 


THE DEPTHS OF THE OCEAN. 


Soundings by other Nations, § 676.—Contrivances for Deep Soundings, 678.— 
Clock-work, 679.—Torpedo, 680.—Magnetic Telegraph, 681.—The Myths of 
the Sea, 683.—Attempts to Sound, 688.—The Observatory Plan for Sounding, 
690.—Practical Difficulties, 692.—Oceanie Circulation, 695.—Law of Plum- 
met’s Descent, 698.—Brooke’s Sounding Apparatus, 700.—Greatest Depths 
yet reached, 701.—Specimens from the Pacific, 702. 


cuarterR “ WE dive,” says Schleiden,* “into the liquid crystal of 


xi. 


— 


Wonders 
of the 
Indian 
Ocean. 


the Indian Ocean, and it opens to us the most wondrous 
enchantments of the fairy tales of our childhood’s dreams. 
The strangely branching thickets bear living flowers. 
Dense masses of Meandrinas and Astrzas contrast with 
the leafy, cup-shaped expansions of the Explanarias, the 
variously-ramified Madrepores, which are now spread out 
like fingers, now rise in trunk-like branches, and now 
display the most elegant array of interlacing branches. 
The colouring surpasses everything: vivid green alter- 
nates with brown or yellow; rich tints of purple, from 
pale red-brown to the deepest blue. Brilliant rosy, yel- 
low, or peach-coloured Nullipores overgrow the decaying 
masses, and are themselves interwoven with the pearl- 
coloured plates of the Retipores, resembling the most 
delicate ivory carvings. Close by wave the yellow and 
lilac fans, perforated like trellis-work, of the Gorgonias. 
The clear sand of the bottom is covered with the thousand 
strange forms and tints of the sea-urchins and star-fishes. 
The leaf-like Flustras and Escharas adhere like mosses 


mic hese antes 


THE DEPTHS OF THE OCEAN. 293 


and lichens to the branches of the corals; the yellow, 
ereen, and purple-striped Limpets cling like monstrous 
cochineal insects upon their trunks. Like gigantic cactus- 
blossoms, sparkling in the most ardent colours, the Sea 
Anemones expand their crowns of tentacles upon the 
broken rocks, or more modestly embellish the flat bottom, 
looking like beds of variegated Ranunculuses. Around 
the blossoms of the coral shrubs play the humming-birds 
of the ocean, little fish sparkling with red or blue metallic 
clitter, or gleaming in golden green, or in the brightest 
silvery lustre. 

“ Softly, like spirits of the deep, the delicate milk-white 
or bluish bells of the jelly-fishes float through this charmed 
world. Here the gleaming violet and gold-green Isabelle, 
and the flaming yellow, black, and vermilion-striped 
Coquette, chase their prey; there the band-fish shoots, 
snake-like, through the thicket, like a long silver ribbon, 
glittering with rosy and azure hues. Then come the 
fabulous cuttle-fish, decked in all colours of the rainbow, 
but marked by no definite outline, appearing and disap- 
pearing, intercrossing, joining company and parting again, 
in most fantastic ways; and all this in the most rapid 
change, and amid the most wonderful play of light and 
shade, altered by every breath of wind, and every slight 
curling of the surface of the ocean. When day declines, 
and the shades of night lay hold upon the deep, this fan- 
tastic garden is lighted up in new splendour. Millions 
of glowing sparks, little microscopic Medusas and Crusta- 
ceans, dance like glow-worms through the gloom. The 
sea-feather, which by daylight is vermilion-coloured, waves 
in a greenish, phosphorescent light. Every corner of it is 


CHAPTER 
xIl. 


§$ 674 


Beauties ct 
the Indian 
Ocean. 


294 THE PHYSICAL GEOGRAPHY OF THE SEA. 


cnarter lustrous. Parts which by day were perhaps dull and 

= brown, and retreated from the sight amid the universal 

brillianey of colour, are now radiant in the most wonder- 

ful play of green, yellow, and red light ; and to complete 

the wonders of the enchanted night, the silver disc, six 

feet across, of the moon-fish,* moves, slightly luminous, 
among the crowd of little sparkling stars. 

§675 “The most luxuriant vegetation of a tropical landscape 


Continned cannot unfold as great wealth of form, while in the variety 


oo" gen, 2d splendour of colour it would stand far behind this 
garden landscape, which is strangely composed exclusively 
of animals, and not of plants; for, characteristic as the 
luxuriant development of vegetation of the temperate 
zones is of the sea bottom, the fulness and multiplicity 
of the marine Fauna is just as prominent in the regions 
of the tropics. Whatever is beautiful, wondrous, or un- 
common in the great classes of fish and Echinoderms, 
jelly-fishes and polypes, and the molluscs of all kinds, is 
crowded into the warm and crystal waters of the tropical 
ovean—rests in the white sands, clothes the rough cliffs, 
clings, where the room is already occupied, like a para- 
site, upon the first comers, or swims through the shallows 
and depths of the elements—while the mass of the vege- 
tation is of a far inferior magnitude. It is peculiar in 
relation to this, that the law valid on land, according to 
which the animal kingdom, being better adapted to ac- 
commodate itself to outward circumstances, has a greater 
diffusion than the vegetable kingdom ; for the Polar Seas 
swarm with whales, seals, sea-birds, fishes, and countless 
numbers of the lower animals, even where every trace of 


* Orthagoriscus mola. 


THE DEPTHS OF THE OCEAN. 295 


vezetation has long vanished in the eternally frozen ice, 
and the cooled sea fosters no sea-weed—that this law, 
I say, holds good also for the sea, in the direction of its 
depth; for when we descend, vegetable life vanishes 
much sooner than the animal, and, even from the depths 
to which no ray of light is capable of penetrating, the 
sounding-lead brings up news at least of living infusoria.” 
—SCHLEIDEN’S Lectures, p. 403-406. 

Until the commencement of the plan of deep-sea sound- 
ings, as now conducted in the American Navy, the bot- 
tom of what the sailors call “ blue water” was as unknown 
to us as is the interior of any of the planets of our 
system. Ross and Dupetit Thouars, with other officers 
of the English, French, and Dutch navies, had attempted 
to fathom the deep sea, some with silk threads, some with 
spun-yarn (coarse hemp threads twisted together), and 
some with the common lead and line of navigation. All 
of these attempts were made upon the supposition, that 
when the lead reached the bottom, either a shock would 
be felt, or the line, becoming slack, would cease to run out. 

The series of systematic experiments recently made 
upon this subject, shows that there is no reliance to be 
placed on such a supposition; for the shock caused by 
striking bottom cannot be communicated through very 
great depths. Furthermore, the lights of experience show 
that, as a general rule, the under currents of the deep sea 
have force enough to take the line out long after the plum- 
met has ceased to do so. Consequently, there is but little 
reliance to be placed upon deep-sea soundings of former 
methods, when the depths reported exceeded eight or ten 
thousand feet. 


CHAPTER 
X11. 


$ 676 
Deep-sea 
soundings 


§ 677 


Mistaken 
notions. 


296 THE PHYSICAL GEOGRAPHY OF THE SEA. 


csarrer Attempts to fathom the ocean, both by sound and 
xIL 
$ 678 

Failure of 


attemptsto and beautiful contrivances for deep-sea soundings were 


pressure, had been made; but out in “blue water” every 
trial was only a failure repeated. The most ingenious 


ecean, — yegorted to. By exploding heavy charges of powder in 
the deep sea, when the winds were hushed and all was 
still, the echo or reverberation from the bottom might, it 
was held, be heard, and the depth determined from the 
rate at which sound travels through water. But though 
the explosion took place many feet below the surface, echo 
was silent, and no answer was received from the bottom. 
Ericsson and others constructed deep-sea leads having a 
column of air in them, which, by compression, would show 
the aqueous pressure to which they might be subjected. 
This was found to answer well for ordinary purposes; but 
in the depths of the sea, where the pressure would be 
equal to several hundred atmospheres, the trial was more 
than this instrument could stand. 
§679 Mr. Baur, an ingenious mechanician of New York, 
Ingenious eonstructed, according to a plan which I furnished him, a 


apparatus 


tor sound- deep-sea sounding apparatus. ‘To the lead was attached, 


ing in 


v bine: Upon the principle of the screw propeller, a small piece of 
clock-work for registering the number of revolutions made 
by the little screw during the descent; and it having 
been ascertained, by experiment in shoal water, that the 
apparatus, in descending, would cause the propeller to 
make one revolution for every fathom of perpendicular 
descent, hands, provided with the power of self-registra- 
tion, were attached to a dial, and the instrument was 
complete. It worked beautifully in moderate depths, but 


failed in “blue water,” from the difficulty of hauling it up 


THE DEPTHS OF THE OCEAN. 297 


if the line used were small, and from the difficulty of 
getting it down if the line used were large enough to 
give the requisite strength for hauling it up. 

An old sea-captain proposed a torpedo, such as is some- 
times used in the whale fishery for blowing up the mon- 
sters of the deep; only this one was intended to explode 
on touching the bottom. It was proposed first to ascer- 
tain by actual experiment the rate at which the torpedo 
would sink, and the rate at which the sound or the gas 
would ascend, and so, by tuming the interval, to deter- 
mine the depth. This plan would afford no specimens of 
the bottom, and its adoption was opposed by other ob- 
stacles. 

One gentleman proposed to use the magnetic telegraph. 
The wire, properly coated, was to be laid up in the sound- 
ing-line, and to the plummet was attached machinery, so 
contrived, that at the increase of every hundred fathoms, 
and by means of the additional pressure, the circuit would 
be restored, somewhat after the manner of Dr. Locke’s 
electro-chronograph, and a message would come up to 
tell how many hundred fathoms up and down the plum- 
met had sunk. As beautiful as this idea was, it was not 
simple enough in practical application to answer our pur- 
poses, 

Greater difficulties than any presented by the problem 
of deep-sea soundings had been overcome in other depart- 
ments of physical research. These plans and attempts 
served to encourage ; nor were they fruitless, though they 
proved barren of practical results. | Astronomers had 
measured the volumes and weighed the masses of the 
most distant planets, and increased thereby the stock of 


CHAPTER 
XII, 


$ 680 
Proposal 
of an old 
sea-cap- 
tain. 


§ 681 


Another 
} voposal, 


§ 682 
These fail 


ures not 
fruitless. 


298 THE PHYSICAL GEOGRAPHY OF THE SEA. 


cuarter human knowledge. Was it creditable to the age that the 

a depths of the sea should remain in the category of an un- 
solved problem? Its “ ooze and bottom” was a sealed 
volume, rich with ancient and eloquent legends, and sug- 
gestive of many an instructive lesson that might be use- 
ful and profitable to man. The seal which covered it 
was of rolling waves many thousand feet in thickness. 
Could it not be broken? Curiosity had always been 
great; yet neither the enterprise nor the ingenuity of 
man had as yet proved itself equal to the task. No one 
had succeeded in penetrating, and bringing up from be- 
yond the depth of two or three hundred fathoms below 
the aqueous covering of the earth any specimens of solid 
matter for the study of philosophers. 

§683 The sea, with its myths, has suggested attractive 
The seaat themes to all people in all ages. Like the heavens, it 
“tect to affords an almost endless variety of subjects for pleasing 

and profitable contemplation ; and there has remained in 
the human mind a longing to learn more of its wonders, 
and to understand its mysteries. The Bible often alludes 
to them. Are they past finding out? How deep is it? 
and what is at the bottom of it? Could not the in- 
genuity and appliances of the age throw some light upon 
these questions ? 

§684 The government was liberal and enlightened; times 
seemed propitious ; but when or how to begin, after all 
these failures, with this interesting problem, was one of 
the difficulties first to be overcome. 

$685 It was a common opinion, derived chiefly from a sup- 
Compt posed physical relation, that the depths of the sea are 

about equal to the heights of the mountains. But this 


THE DEPTHS OF THE OCEAN. 299 


conjecture was, at best, only a speculation. Though as 
plausible, it did not satisfy. There were, in the depths —— 
of the sea, untold wonders and inexplicable mysteries : 
therefore the contemplative mariner, as in mid-ocean he 
looked down upon its gentle bosom, continued to expe- 

rience sentiments akin to those which fill the mind of the 
devout astronomer when, in the stillness of the night, he 

looks out upon the stars, and wonders. 

Nevertheless, the depths of the sea still remained as § 686 
fathomless and as mysterious as the firmament above. Depth ot 
Indeed, telescopes of huge proportions and of vast space- Cease 
penetrating powers had been erected here and there by terious 
the munificence of individuals, and attempts made with 
them to gauge the heavens and sound out the regions of 
space. Could it be more difficult to sound out the sea 
than to gauge the blue ether and fathom the vaults of 
the sky? The result of the astronomical undertakings* 
lies in the discovery that what, through other instruments 
of less power, appeared as clusters of stars, were, by those 
of larger powers, separated into groups, and what had 
been reported as nebulze could now be resolved into clus- 
ters ; that, in certain directions, the abyss beyond these 
faint objects is decked with other nebulee, which these 
great instruments may bring to light, but cannot resolve ; 
and that there are still regions and realms beyond, which 
the rays of the brightest sun in the sky have neither the 
intensity nor the force to reach, much less to penetrate. 

And what is more, these monster instruments have re- 
vealed to us, in those distant regions, forms or aggrega- 
tions of matter which suggest to some the idea of the 


* See the works of Herschel and Rosse, and their telescopes. 


300 THE PHYSICAL GEOGRAPHY OF THE SEA. 


nzarter existence of physical forces there that we do not under- 
** stand, and which raise the question in speculative minds, 
Is gravitation a universal thing, and do its forces pene- 
trate every abyss of space ? 
§ 687 Could we not gauge the sea as well as the sky, and 
wana't, devise an instrument for penetrating the depths of the 
the ocean. Ocean as well as the depths of space? Mariners were 
curious concerning the bottom of the sea. Though no- 
thing thence had been brought to light, exploration had 
invested the subject with additional interest, and in- 
creased the desire to know more. In this state of thie 
case, the idea of a common twine thread for a sounding- 
line, and a cannon-ball for a sinker, was suggested. It 
was a beautiful conception ; for, besides its simplicity, it 
had in its favour the greatest of recommendations—it 
could be readily put into practice. 

ieee Well-directed attempts to fathom the ocean began now 
to be made with such a line and plummet, and the public 
mind was astonished at the vast depths that were at first 
reported. 

$688 Lieutenant Walsh, of the United States schooner 
various Taney, reported a cast with the deep-sea lead at thirty- 
eddepths. four thousand feet without bottom. His sounding-line 

was an iron wire more than eleven miles in length. 
Lieutenant Berryman, of the United States brig Dol- 
phin, reported another unsuecessful attempt to fathom 
mid-ocean with a line thirty-nine thousand feet in length. 
Captain Denham, of her Britannic Majesty’s ship Herald, 
reported bottom in the South Atlantic at the depth of 
forty-six thousand feet ; and Lieutenant J. P. Parker, of 


the United States frigate Congress, afterward, in at- 


THE DEPTHS OF THE OCEAN. 301 


tempting to sound near the same region, let go his plum- 
met, and saw it run out a line fifty thousand feet long, as 
though the bottom had not been reached. 

The three last-named attempts were made with the 
sounding-twine of the American Navy, which has been 
introduced in conformity with a very simple plan for 
sounding out the depths of the ocean. It involved for 
each cast only the expenditure of a cannon-ball, and twine 
enough to reach the bottom. This plan was introduced 
as a part of the researches conducted at the National 
Observatory, and which have proved so fruitful and bene- 
ficial, concerning the winds and currents, and other pheno- 
mena of the ocean. These researches had already received 
the approbation of the Congress of the United States ; 
for that body, in a spirit worthy of the representatives of 
a free and enlightened people, had authorized the Secre- 
tary of the Navy to employ three public vessels to assis* 
in perfecting the discoveries, and in conducting the inves- 
tigations connected therewith. 

The plan of deep-sea soundings finally adopted, and now 
in practice, is this: Every vessel of the navy, when she 
puts to sea, is, if she desires it, furnished with a sufficient 
quantity of sounding-twine, carefully marked at every 
length of one hundred fathoms—six hundred feet—and 
wound on reels of ten thousand fathoms each. It is made 
the duty of the commander to avail himself of every 
favourable opportunity to try the depth of the ocean, 
whenever he may find himself out upon “blue water.” 
For this purpose he is to use a cannon-ball of thirty-two 
or sixty-eight pounds asa plummet. Having one end of 
the twine attached to it, the cannon-ball is to be thrown 


CHAPTER 
XII. 


§ 689 
American 
sounding 
plummets, 
&e, 


§ 690 
Plan of 
deep-sea 
soundings 
now in 
practice. 


CHAPTER 
XII. 


¢ 691 


Imple- 
ment used. 


§ 692 


Practical 
ditticulties. 


Renewed 
attempts. 


S02 THE PHYSICAL GEOGRAPHY OF THE SEA. 


overboard from a boat, and suffered to take the twine 
from the reel as fast as it will. 

The reel is made to turn easily. A silk thread, or 
the common wrapping-twine of the shops, would, it was 
thought, be strong enough for this purpose; for it was 
supposed there would be no strain upon the line, except 
the very sight one required to drag it down; and the 
twine having nearly the specific gravity of sea water, this 
strain would, it was imagined, be very slight. Moreover, 
when the shot reached the bottom, the line, it was thought, 
would cease to run out; then breaking it off, and seeing 
how much remained upon the reel, the depth of the sea 
could be ascertained at any place and time, simply at the 
expense of one cannon-ball and a few pounds of common 
twine. 

But practical difficulties that were not expected at all 
were lurking in the way, and afterward showed themselves 
at every attempt to sound; and it was before these prac- 
tical difficulties had been fairly overcome that the great 
soundings’ were reported. In the first place, it was dis- 
covered that the line, once started and dragged down 
into the depths of the ocean, never would cease to run 
out, and, consequently, that there was no means of know- 
ing when, if ever, the shot had reached the bottom. And 
in the next place, it was ascertained that the ordinary 
twine‘would not do; that the sounding-line, in going down, 
was really subjected to quite a heavy strain, and that, con- 
sequently, the twine to be used must be strong. It was 
therefore subjected to a test which required it to bear a 
weight of at least sixty pounds freely suspended in the 
air. So we had to go to work anew, and make several 


1 § 676. 2 9 G33. 3 $ O77. * § 687, 


THE DEPTHS OF THE OCEAN. 303 


bundred thousand fathoms of sounding-twine especially oaeee 
for the purpose. It was small, and stood the test re- — 
quired, a pound of it measuring about six hundred feet in 
length. 

The officers intrusted with the duty soon found that § 693 
the soundings could not be made from the vessel with any Yeh!" 
certainty as to the depth. It was necessary that a boat 
should be lowered, and the trial be made from it; the men 
with their oars keeping the boat from drifting, and main- 
taining it in such a position that the line should be “up 
and down” the while. 


That the line would continue to run out after the can- § 694 


Supposed 
cause of 


non-ball had reached bottom, was explained by the con- 
jecture, that there is in the ocean, as in the air, a system Ui. 
of currents and counter-currents, one above the other, and 
that it was one or more of these submarine currents, 
operating upon the bight of the line, which caused it to 
continue to run out after the shot had reached the bot- 
tom. In corroboration of this conjecture, it was urged, 
with a truth-like force of argument, that it was these 
under-currents, operating with a swigging force upon the 
bights of the line—for there might be several currents 
running in different directions, and operating upon it at 
the same time—which caused it to part whenever the reel 
was stopped and the line held fast in the boat. 

A powerful train of circumstantial evidence was this, § 695 
(and it was derived from a source wholly unexpected,) Ocea'e 


circulatior 
going to prove the existence of that system of oceanic imdrectiy 
. 5 - x proved. 
circulation which the climates, and the offices and the 
s . . . . ° 1 
adaptations of the sea require; and which its inhabitants, 


in their mute way, tell us of. 


1 § 498. 


304 THE PHYSICAL GEOGRAPHY OF THE SEA, 


cnarteR This system of circulation commenced on the third day 
XII. ee F ; : : 
— of creation, with the “ gathering together of the waters,” 
§ 696 


Time of 
crculation Tong as sea water shall possess the properties of saltness 


commenc- 


ane and fluidity. 


which were “ called seas,” and doubtless will continue as 


$697 In making these deep-sea soundings, the practice is to 


we wot time the hundred fathom marks as they successively go 


estetlish- out; and by always using a line of the same size and 
“make,” and a sinker of the same shape and weight, we 
at last established the law of descent. Thus the mean 


of our experiments gave us, for the sinker and twine 


used— 
2m. 21s. as the average time of descent from 400 to 500 fathoms. 
3m. 26s. is 5S +, 1) LODO) LOOT SS 
4m. 29s. 5 se 3 800;to T900N a: 


§ 698 Now, by aid of the law here indicated, we could tell 
very nearly when the ball ceased to carry the line out, 
and when, of course, it began to go out in obedience to 
the current and drift alone ; for currents would sweep the 
line out at a uniform rate, while the cannon-ball would 
drag it out at a decreasing rate. 

§ 699 The development of this law was certainly an achieve 

Advan- ment, for it enabled us to show that the depth of the sea 


tages of 


the diss at the places named’ was not so great as reports made it. 
covery ot 


the law of "|"hese researches were interesting; the problem in hand 


was important, and it deserved every effort that in- 

genuity could suggest for reducing it to a satisfactory 
solution. 

§700 As yet, no specimens of the bottom had been brought 

No spe’ up. The line was too small, the shot was too heavy, and 


mens of 


porte it could not be weighed; and if we could reach the bot- 


tom, why should we not know its character? In this 


1 § 688. 


THE DEPTHS OF THE OCEAN. 305 


state of the case, Passed Midshipman J. M. Brooke, 
United States Navy, who at the time was associated with 
me on duty at the Observatory, proposed a contrivance 
by which the shot, on striking the bottom, would detach 
itself from the line, and send up a specimen of the bottom. 
This beautiful contrivance, called Brooke’s Deep-sea Sound- 
ing Apparatus, is represented in Plates II. and III. 

A is a cannon ball, having a hole through it for the rod 
B. Plate II. represents the rod, B; the slings, D D, with 
the shot slung, and in the act of being lowered down. 
Plate III. represents the apparatus in the act of stmking 
the bottom, and shows how the shot is detached, and how 
specimens of the bottom are brought up, by adhering to 


> 


a little soap or tallow,* called “arming,” in the cup, C, 
at the lower end of the rod, B. With this contrivance, 
specimens of the bottom have been brought up from the 
depth of more than two miles. 

The greatest depths at which the bottom of the sea has 
been reached with the plummet are in the North Atlantic 
Ocean, and the places where it has been fathomed do not 
show it to be deeper than twenty-five thousand feet. 

The deepest place in this ocean’ is probably between 
the parallels of 35° and 40° north latitude, and imme- 
diately to the southward of the Grand Banks of New- 
foundland. The first specimens have been received from 
the coral sea of the Indian Archipelago and from the 
North Pacific. They were collected by the surveying 
expedition employed in those seas. A few soundings 
have been made in the South Atlantic, but not enough to 
justify deduction as to its depths or the shape of its floor. 


* The barrel of a common quill attached to the rod hag been found to answer 
better. 1 Plate XI. 
20 


CHAPTER 
xIJ, 


Brooke's 
new con- 
trivance. 


§ 701 
Greatest 
depths at- 
tained. 


§ 702 
Greatest 
probable 
depth. 


306 THE PHYSICAL GEOGRAPHY OF THE SEA. 


CHAPTER XIII. 


THE BASIN OF THE ATLANTIC. 


Tts Shape, § 704.—Plate XI., 709.—The Deepest Part of the Atlantic, 710.— 
The Use of Deep-sea Soundings, 7183.—The Telegraphic Plateau, 714.—It ex- 
tends around the Earth as a Ridge, 715.—The first Specimens with Brooke's 
Lead, 717.—The Bottom of the Seaa Burial-place, 724.—The levelling Agencies 
at work there, 730.—Marine Insects presented in a new Light, 734.—Conser- 
vators of the Sea, 739.—Calcareous Shells, 742.—Tallying marine Currents, 
745.—A Cast of 7000 Fathoms in the Indian Ocean, 750.—Bottom from the 
Coral Sea, 751.—Microscopic Examination of, 753.—The Bed of the Ocean, 761. 


curren ‘THE BASIN OF THE ATLANTIC, according to the deep-sea 
Sie soundings made by the American Navy, in the manner 
hasin of Gescribed in the foregoing chapter, is shown on Plate VI. 
Ausntc “This plate refers chiefly to that part of the Atlantic which 
is included within our hemisphere. 

§704 In its entire length, the basin of this sea is a long 
trough, separating the Old World from the New, and ex- 
tending probably from pole to pole. 

§705 This ocean-furrow was scored into the solid crust of 
our planet by the almighty hand, that there the waters 
which “he called seas” might be gathered together, so as 
to “let the dry land appear,” and fit the earth for the 
habitation of man. 

§706 From the top of Chimborazo to the bottom of the Atlan- 
tic, at the deepest place yet reached by the plummet in the 
North Atlantic, the distance, in a vertical line, is nine miles. 

$707 Could the waters of the Atlantic be drawn off, so as 

hance to expose to view this great sea-gash, which separates 
continents, and extends from the Arctic to the Antarctic, 
it would present a scene the most rugged, grand, and im- 


THE BASIN OF THE ATLANTIC. 307 


posing. The very ribs of the solid earth, with the foun- cuapree 
dations of the sea, would be brought to light, and we =~ 
should have presented to us at one view, in the empty 
cradle of the ocean, “a thousand fearful wrecks,’ with 
that dreadful array of dead men’s skulls, great anchors, 
heaps of pearls and inestimable stones, which, in the 
dreamer’s eye, lie scattered on the bottom of the sea, 
making it hideous with sights of ugly death. 

To measure the elevation of the mountain-top above § 708 
the sea, and to lay down upon our maps the mountain M™pert- 


ance of tha 
5 ar = 5 ~ . aay = = hysical 
ranges of the earth, is regarded in geography as an im pene. 


portant thing, and rightly so. Equally important is it, of the sea. 
in bringing the physical geography of the sea regularly 
within the domains of science, to present its orography, 

by mapping out the bottom of the ocean, so as to show 

the depressions of the solid parts of the earth’s crust there 

below the sea-level. 

Plate XI. presents the second attempt at such a map. $ 709 
It relates exclusively to the bottom of that part of the Rewws 
Atlantic Ocean which lies north of 10° south. It is stip- *! 
pled with four shades; the darkest (that which is near- 
est the shore-line) shows where the water is less than six 
thousand feet deep ; the next, where it is less than twelve 
thousand feet; the third, where it is less than eighteen 
thousand feet ; and the fourth, or lightest, where it is not 
over twenty-four thousand feet deep. The blank space 
south of Nova Scotia and the Grand Banks includes a 
district within which very deep water has been reported, 
but, from casts of the deep-sea lead, which, upon discussion, 
do not appear satisfactory. 

The deepest part of the North Atlantic’ is probably § 710 


U § 702, 


on 


308 THE PHYSICAL GEOGRAPHY OF THE SEA. 


onaprer somewhere between the Bermudas and the Grand Banks, 
xu put how deep it may be yet remains for the cannon-ball 
and sounding-twine to determine. 

§711 The waters of the Gulf of Mexico are held in a basin 
Nuc, about a mile deep in the deepest part. 

¢712 THE BorromM OF THE ATLANTIC, or its depressions below 
B efiaan ot the sea-level, are given, perhaps, on this plate, with as 

much accuracy as the best geographers have been enabled 
to show on a map the elevations above the sea-level of 
the interior either of Africa or Australia. 

§713 “What is to be the use of these deep-sea soundings ?” 
ae is a question that often occurs; and it is as difficult to 
soundings he answered in categorical terms as Franklin’s question, 

“What is the use of a new-born babe?” Every physical 

fact, every expression of nature, every feature of the 
earth, the work of any and all of those agents which 
make the face of the world what it is and as we see it, 

is interesting and instructive. Until we get hold of a 
group of physical facts, we do not know what practical 
bearings they may have, though right-minded men know 

that they contain many precious jewels, which science, or 

the expert hand of philosophy, will not fail to bring out, 
polished and bright, and beautifully adapted to man’s 
purposes. Already we are obtaining practical answers to 

this question as to the use of deep-sea soundings ; for, as 

soon as they were announced to the public, they forthwith 
assumed a practical bearing in the minds of men with regard 

to the question of a submarine telegraph across the Atlantic. 

$714 There is at the bottom of this sea, between Cape Race 
Plateau jn Newfoundland and Cape Clear in Ireland, a remark- 


between 


eland able steppe, which is already known as the telegraphic 


and New- 
foundland 


THE BASIN OF THE ATLANTIC. 309 


plateau.’ A company is now engaged with the project CHAPTER 
of a submarine telegraph across the Atlantic. It is pro- — 

° . Atlantic 
posed to carry the wires along this plateau, from the Telegrapn 


eastern shores of Newfoundland to the western shores of 7 ?"” 
Treland. The great-circle distance between these two 
shore-lines is one thousand six hundred and forty miles, 
and the sea along the route is probably nowhere more 
than ten or twelve thousand feet deep. This company, 
it is understood, consists of men of enterprise and wealth, 
who have satisfied themselves as to the practicability of 
the scheme. They have made a contract with a party 
in England, who have agreed to deliver to them, by June 
1858, a telegraphic cable, stretched from Ireland, upon 
this plateau, to Newfoundland. It was this company 
that attempted to stretch a telegraphic cable from Port au 
Basque, in Newfoundland, to Cape Breton, and lost it. It 
is hoped that no such failure will happen to the great line, 
for, with proper precaution and management, success is 
certain. 
There appears to be, corresponding to this elevation of § 715 

the bottom of the sea, a ridge on the land which runs 4 ridge on 


land corre- 


nearly, if not entirely, around the earth. Leaving this pogtdine 
continent between the parallels of 45° and 50° north, the in the sea. 
British Islands are within its range. Passing thence to 
the Continent, we recognise it in the great “ divide” which 
separates the drainage of the Arctic Ocean from the 
drainage south. In Asia it rises up into a chain of 
steppes and mountains, extending across that continent 
from west to east, and disappearing on the shores of the 
Pacific. We do not know how it is at the bottom of the 
“Grand Ocean ;” but the chain of Aleutian Islands, rising 


1 § 1025, 


310 THE PHYSICAL GEOGRAPHY OF THE SEA. 


cnarrer Out of the water midway between Asia and America, 
~~ seems to suggest that it is there also. However, if we 
run the eye along to America, we shall perceive again, 

as soon as we come to this continent, indications of 

this ridge, which here divides the waters that flow north 

from those that seek the ocean in more southern latitudes: 

§716 It was upon this ridge or plateau, as it crosses the 
Specimens Atlantic, that Brooke’s sounding apparatus brought up 


brought up 
from this jts first trophies from the bottom of the sea. These 


Pri specimens Lieutenant Berryman and his officers judged 
to be clay; but they took the precaution to label them, 
carefully to preserve them, and, on their return to the 
United States, to send them to the proper bureau. 
They were divided; a part was sent for examination to 
Professor Ehrenberg of Berlin, and a part to Professor 
Bailey of West Point, eminent microscopists both. I 
have not heard from the former, but the latter, in No- 
vember 1853, thus responded :— 

$717 “Tam greatly obliged to you for the deep soundings 


Professor 
Bailey’s 


remarkson oreat interest. They are exactly what I have wanted to 
tpecimens. 


get hold of. The bottom of the ocean at the depth of 
more than two miles I hardly hoped ever to have a chance 


you sent me Jast week, and I have looked at them with 


of examining; yet, thanks to Brooke’s contrivance, we 
have it clean and free from grease, so that it can at once 
be put under the microscope. I was greatly delighted 
to find that all these deep soundings are filled with 
microscopic shells ; not a particle of sand or gravel exists 
in them, They are chiefly made up of perfect little cal- 
eareous shells (Foraminiferw), and contain also a small 
number of silicious shells (Diatomacee). 


~~ 


THE BASIN OF THE ATLANTIC. 311 


“Tt is not probable that these animals lived at the 
depths where these shells are found; but I rather think 
that they inhabit the waters near the surface, and, when 
they die, their shells settle to the bottom. With refer- 
ence to this point, I shall be very glad to examine bottles 
of water from various depths which were brought home 
by the Dolphin, and any similar materials, either ‘ bottom ’ 
or water from other localities. I shall study them care- 
1 The results already obtained are of very great 
interest, and have many important bearings on geology 
and zoology..... 

“T hope you will induce as many as possible to collect 
soundings with Brooke’s lead in all parts of the world, so 
that we can map out the animalculze as you have the 
whales. Get your whalers also to collect mud from pan- 
cake ice, &., in the Polar Regions; this is always full of 
interesting microscopic forms.” 

These little mites of shells seem to form but a slender 
clew indeed by which the chambers of the deep are to be 
threaded, and mysteries of the ocean revealed; yet the 
results are suggestive : in right hands, and to right minds, 
they are guides to both light and knowledge. 

The first noticeable thing the microscope gives of these 
specimens is, that all of them are of the animal, not one 
of the mineral kingdom. 

The ocean teems with life, we know. Of the four 
elements of the old philosophers—fire, earth, air, and 
water—perhaps the sea most of all abounds with living 
creatures. The space occupied on the surface of our 
planet by the different families of animals and their re- 
mains is inversely as the size of the individual,—the 


CHAPTER 
XIII. 


Remarks 
continued. 


§ 718 


Use of lit- 
tle shells. 


§ 719 


§ 720 


The ocean 
teems with 
life. 


CHAPTER 
XIII. 
Space oc- 
eupied by 
different 
animals. 


§ 721 


No sand 
among the 
small 
shells. 


Inference. 


S22 
Professor 
Bailey's 
remarks 
on the 
animal- 
culx. 


3l2 THE PHYSICAL GEOGRAPHY OF THE SEA. 


smaller the animal, the greater the space occupied by his 
remains. Though not invariably the case, yet this rule 
to a certain extent is true, and will therefore answer our 
present purposes, which are simply those of illustration : 
Take the elephant and his remains, or a microscopic 
animal and his, and compare them. The contrast, as to 
space occupied, is as striking as that of the coral reef or 
island with the dimensions of the whale. The grave-yard 
that would hold the corallines is larger than the grave- 
yard that would hold the elephants. 

We notice another practical bearing in this group of 
physical facts that Brooke’s apparatus fished up from the 
bottom of the deep sea. Bailey, with his microscope, 
could not detect a single particle of sand or gravel among 
these little mites of shells) They were from the great 
telegraphic plateau ;? and the inference is, that there, if 
anywhere, the waters of the sea are at rest. There was 
not motion enough there to abrade these very delicate 
organisms, nor current enough to sweep them about and 
mix up with them a grain of the finest sand, nor the 
smallest particle of gravel torn from the loose beds of 
debris that here and there strew the bottom of the sea. 
This plateau is not too deep for the wire to smk down 
and rest upon; yet it is not so shallow that currents, or 
icebergs, or any abrading force, can derange the wire after 
it is once lodged upon it. 

As Professor Bailey remarks, the animalcule, whose 
remains Brooke’s lead has brought up from the bottom 
of the deep sea, probably did not live or die there. They 
would have had no light there ; and, had they lived there, 
their frail little textures would have been subjected in 


DSA Siar 


THE BASIN OF THE ATLANTIC. ales 


their growth to a pressure upon them of a column of cmaprra 
XIII. 


water twelve thousand feet high, equal to the weight of —— 
four hundred atmospheres. They probably lived and 
sported near the surface, where they could feel the genial 
influence of both light and heat, and were buried in the 
lichen caves below after death. 

Brooke’s lead and the microscope, therefore, it would g 723 
seem, are about to teach us to regard the ocean in a new New views 


of ocean 


light. Its bosom, which so teems with animal life ; itg opened 
i Es 3 7 up by 
face, upon which time writes no wrinkles—makes no Brooke's 
° > ° 3 lead and 
impression ; are, it would now seem, as obedient to the micro- 
scope. 


oreat law of change as is any department whatever, either 
of the animal or the vegetable kingdom. It is now sug- 
gested that henceforward we should view the surface of 
the sea as a nursery teeming with nascent organisms, its 
depths as the cemetery for families of living creatures 
that outnumber the sands on the sea-shore for muititude. 
Where there is a nursery, hard by there will be found § 724 
also a grave-yard: such is the condition of the animal Sue of 


the sea a 


world. But it never occurred to us before to consider nS 


the surface of the sea as one wide nursery, its every ac 
yard. 


ripple as a cradle, and its bottom one vast burial-place. 
On those parts of the solid portions of the earth’s crust § 725 
which are at the bottom of the atmosphere, various Wasting 


agents on 


agents are at work, levelling both upward and down- eaten 
ward. Heat and cold, rain and sunshine, the winds and 
the streams, all, assisted by the force of gravitation, are 
unceasingly wasting away the high places on the land, 


and as perpetually filling up the low. 


~] 
bo 
fon) 


But in contemplating the levelling agencies that are at § 
work upon the solid portions of the crust of our planet, 


OHAPTER 
XIII. 


§ 727 
No abrad- 
ing pro- 
cesses in 
the sea. 


§ 728 


§ 729 
Specula- 
tions. 


§ 730 
Effects of 
animal- 
cule on 
the bottom 
of ocean. 


314 THE PHYSICAL GEOGRAPHY OF THE SEA. 


one is led, at first thought, almost to the conclusion that 
the levelling agents, however active they may be at the 
bottom of the atmosphere, are comparatively powerless 
at the bottom of the sea. 

In the deep sea there are no abrading processes at 
work; neither frosts nor rains are felt there, and the 
force of gravitation is so paralyzed down there, that it 
cannot use half its power, as on the dry land, in tearing 
the overhanging rock from the precipice, and casting it 
down into the valley below. . 

When considering the bottom of the ocean, we have, 
in the imagination, been disposed to regard the waters of 
the sea as a great cushion, placed between the air and 
the bed of the ocean to protect and defend it from these 
abrading agencies of the atmosphere. 

The geological clock may, we thought, strike new 
periods; its hands may point to era after era; but, so 
long as the ocean remains in its basin—sv long as its 
bottom is covered with blue water—so long must the 
deep furrows and strong contrasts in the solid crust below 
stand out bold, ragged, and grand. Nothing can fill up 
the hollows there ; no agent now at work, that we know 
of, can descend into its depths, and level off the floors of 
the sea. 

But it now seems that we forgot these oceans of ani- 
maleule, that make the surface of the sea sparkle and | 
glow with life. They are secreting from its surface solid 
matter for the very purpose of filling up those cavities 
below. These little marine insects are building their 
habitations at the surface and when they die, their 
remains, in vast multitudes, sink down and settle upon 


THE BASIN OF THE ATLANTIC. ols 


the bottom. They are the atoms of which mountains 
are formed and plains spread out. Our marl-beds, the 
clay in our river-bottoms, large portions of many of the 
great basins of the earth, are composed of the remains of 
just such little creatures as these, which the ingenuity of 
Brooke and the industry of Berryman have enabled us to 
fish up from the depth of more than two miles (twelve 
thousand feet) below the sea-level. 

These foraminifere, therefore, when living, may have 
been preparing the ingredients for the fruitful soil of a 
land that some earthquake or upheaval, in ages far away 
in the future, may be sent to cast up from the bottom of 
the sea for man’s use. 

The study of these “sunless treasures,” recovered with so 
much ingenuity from the rich bottom of the sea, suggests 
new views concerning the physical economy of the ocean. 

In the chapter on the Salts of the Sea, p. 208, I endea- 
voured to show how sea-shells and marine insects may, 
by reason of the offices which they perform, be regarded 
as compensations in that exquisite system of physical 
machinery by which the harmonies of nature are pre- 
served, 

But the treasures of the lead and revelations of the 
microscope present the insects of the sea in a new and 
still more striking light. We behold them now serving 
not only as compensations by which the motions of the 
water in its channels of circulation are regulated and cli- 
mates softened, but acting also as checks and balances 
by which the equipoise between the solid and the fluid 
matter of the earth is preserved. 

Should it be established that these microscopic crea- 


CHAPTER 
XIII. 


a! 
§ 73 


Specula- 
tion. 


§ 732 


New views 


733 


mn 


§ 734 
Effects 
produced 
by animal- 
cue. 


$ 735 


CHAPTER 
XIII. 


Conserva- 
tors of the 
ocean. 


§ 736 


Substances 
discharged 
into sea by 
rivers. 


§ 738 


Micro- 
scopic or- 
ganisms 
work on 
the sur- 
face. 


§ 739 
What re- 
gulates the 


316 THE PHYSICAL GEOGRAPHY OF THE SEA. 


tures live at the surface, and are only buried at the bot- 
tom of the sea, we may then view them as conservators 
of the ocean; for, in the offices which they perform, they 
assist to preserve its status by secreting the salts which 
the rivers and the rains bring down to the sea, and thus 
maintain the purity of its waters. 

The waters of the Mississippi and the Amazon, toge- 
ther with all the streams and rivers of the world, both 
great and small, hold in solution large quantities of lime, 
soda, iron, and other matter. They discharge annually 
into the sea an amount of this soluble matter which, if 
precipitated and collected into one solid mass, would no 
doubt surprise and astonish the boldest speculator with 
its magnitude. 

This soluble matter cannot be evaporated. Once in 
the ocean, there it must remain; and as the rivers are 
continually pouring in fresh supplies of it, the sea, it has 
been argued, must continue to become more and more salt. 

Now, the rivers convey to the sea this solid matter 
mixed with fresh water, which, being lighter than that 
of the ocean, remains for a considerable time at or near 
the surface. Here the microscopic organisms of the deep- 
sea lead are continually at work, secreting this same lime 
and soda, &e., and extracting from the sea water all this 
solid mater, as fast as the rivers bring it down and empty 
it into the sea. They live and die at the surface, then 
sinking, the bottom of the sea is strewed with them. 

Thus we haul up from the deep sea specimens of dead 
animals, and recognise in them the remains of creatures 


saltness of which, though invisible to the naked eye, have neverthe- 


the sea. 


less assigned to them a most important office in the phy- 


THE BASIN OF THE ATLANTIC. oe 


sical economy of the Eee namely, that of regulating cnaprrer 
the saltness of the sea.’ ees 

This view suggests many contemplations. Among § 740 
them, one in which the ocean is presented as a vast che- ccna 
mical bath, where the solid parts of the earth are washed, micalbath. 
filtered, and precipitated again as solid matter, but in a 
new form, and with fresh properties. 

Doubtless it is only a re-adaptation—though it may be 
in an improved form—of old, and perhaps effete matter, to 
the uses and well-being of man. 

These are speculations merely ; they may be fancies g 741 
without foundation, but idle they are not, I am sure: for eee 
when we come to consider the agents by which the phy- lation 
sical economy of this our earth is regulated, by which 
this or that result is brought about and accomplished in 
this beautiful system of terrestrial arrangements, we are 
utterly amazed at the offices which have been performed, 
the work which has been done, by the animalculze of the 
water. 

But whence come the little calcareous shells which § 742 
Brooke’s lead has brought up, in proof of its sounding, Where 


from the depth of two miles and a quarter? Did they ite 7 
live in the surface waters immediately above? or is their 
habitat in some remote part of the sea, whence, at their 

death, the currents were sent forth as pall-bearers, with 

the command to deposit their remains where the plummet 

found them ? 

In this view, these little organisms become doubly § 743 

interesting. When dead, the descent of the shell to its Descent 


final resting-place would not, it may be supposed, be very “4 
rapid. It would partake of the motion of the sea water 


1 § 563. 


315 THE PHYSICAL GEOGRAPHY OF THE SEA. 


evartzer in Which it lived and died, and probably be carried along 
“with it in its channels of circulation for many a long mile. 
744 The microscope, under the eye of Ehrenberg, has en- 
abled us'to put tallies on the wings of the wind, to learn 

of them somewhat concerning its “ circuits.” 
§745 Now, may not these shells, which were so fine and 
hated impalpable that the officers of the Dolphin took them to 
tothe be amass of unctuous clay—may not, I say, these, with 


course of 


eo other specimens of soundings yet to be collected, be all 

tion. converted by the microscope into tallies for the waters of 
the different parts of the sea, by which the channels 
through which the circulation of the ocean is carried on 
are to be revealed ? 

§746 Suppose, for instance, that the dwelling-place of the 

Sspposed’ little shells which compose this specimen from that part 
of the ocean be ascertained, by referring to living types, 
to be the Gulf of Mexico, or some other remote region,— 
that the habitat and the burial-place, in every instance, 
be far removed from each other ; by what agency, except 
through that of currents, can we suppose these little crea- 
tures—themselves not having the powers for more than 
a very restricted locomotion—to come from the place of 
their birth, or to travel to that of their burial ? 

$747 Man can never see, he can only touch the bottom of 

Soverane’ the deep sea, and then only with the plummet. What- 

escent ever it brings up thence is to the philosopher matter of 

Cees powerful interest ; for by such information alone as he 
may gather from a most careful examination of such 
matter, the amount of human knowledge concerning 
nearly all that portion of our planet which is covered by 
the sea must depend. 


THE BASIN OF THE ATLANTIC. 319 


Every specimen of bottom from the deep sea is, there- 
fore, to be regarded as probably containing something 


2 
. . . . PS) 
precious in the way of contribution to the sources of 


human knowledge; and each as it is brought up will be 
viewed with increasing interest, and will suggest to us 
thoughts more and more profitable concerning the wonders 
of the deep. 

“There has been sent,” says Brooke, in a letter from 
the Surveying Expedition of the North Pacific, “a table 
of temperatures at various depths, from one hundred to 
five hundred fathoms, and two reports of experiments in 
deep-sea soundings. Several unsuccessful attempts to 
sound from the ship were made under the direction of 
Captain Ringgold, but were considered unworthy of a 
remark—in which opinion I coincide; for, at consider- 
able depths, one is entirely dependent upon the times of 
the hundred fathoms. As a general thing, I suppose a 
hundred thousand fathoms would all be eventually taken 
from the reel by the drift of the ship. On one of these 
occasions a breeze sprang up on the quarter, shooting the 
ship ahead in such a manner as to render the cast utterly 
worthless. 


CHAPTER 
XIII, 


§ 749 
Brooke's 
remarks 
on tem- 
perature 
and sound- 


ings, 


“From our experience in the Indian Ocean and Coral gs 750 


Sea, I am inclined to believe that there is no depth from 
which specimens of the bottom may not be obtained. It 
will ever be a source of regret that, owing to circum- 
stances beyond my control, we were unsuccessful in 
recovering the line and specimen after reaching bottom 
with 7040 fathoms in the Indian Ocean. Such oppor- 
tunities are rare in that locality; yet, owing to the 
current of sixty miles, it will be a difficult matter to 


Remarks 
continued 
Indian 
Ocean. 


CHAPTER 
XIII. 


§ 751 


Cast in the 
Coral Sea. 


SP 

~] 
qn 
bo 


§ 753 
Professor 
Bailey's 
remarks 
on speci- 

. mens. 


320 THE PHYSICAL GEOGRAPHY OF THE SEA. 


determine the absolute depth. That current was not as 
superficial as one might at first suppose, for it was during 
the latter part of the operation that the boat experienced 
its effect, and it would seem that, had the current been 
superficial, the line would have given indication by tend- 
ing ahead, whereas it ran right down. Moreover, that 
current was local, which adds to the probability of its 
depth. 

“The cast made in the Coral Sea was satisfactory in 
every respect. The arming-rod came up with its lower 
extremity completely coated with what appeared to be a 
calcareous clay of such adhesive and tenacious character 
as to preserve the marks of the shot made in slipping off. 
Tn fact, we had fallen upon one of those beds which evi- 
dently present the characteristic formations of England.” 

This specimen from the Coral Sea, lat. 13° south, 
long. 162° east, was brought up by Brooke’s sounding- 
rod from the reported depth of 2150 fathoms. 

Professor Bailey, to whom the specimen was sent for 
microscopic examination, replied: “ You may be sure I 
was not backward in taking a look at the specimens you 
sent me, which, from their locality, promised to be so 
interesting. The sounding from 2150 fathoms, although 
small in quantity, is not bad in quality, yielding repre- 
sentatives of most of the great groups of microscopic 
organisms usually found in marine sediments. 

“The predominant forms are silicious spicules of sponges. 
Various forms of these occur; some long and spindle- 
shaped or acicular, others pin-headed, some three-spined, 
&e., &e. 


“The Diatoms (silicious infusoria of Ehrenberg) are 


THE BASIN OF THE ATLANTIC. Beal 


very few in number, and mostly fragmentary. I found, 
howeyer, some perfect valves of a Coscinodiscus. 

“The Foraminiferze (Polythalamia of Ehrenberg) are 
very rare, only one perfect shell being seen, with a few 
fragments of others. 

“The Polycistiniz are present, and some species of 
Haliomma were quite perfect. Fragments of other forms 
of this group indicate that various interesting species 
might be obtained if we had more of the material. 

“You see by the above that this deep-sounding differs 
considerably from those obtained in the Atlantic. The 
Atlantic soundings were almost wholly composed of cal- 
careous shells of the Foraminifera ; these, on the contrary, 
contain very few Foraminiferee, and are of a silicious 
rather than of a calcareous nature. This only makes the 
condition of things in the northern Atlantic the more inter- 
esting, because,” says this philosopher, “they prove that 
deep water is not necessarily underlaid by foraminiferous 
deposits, and that some peculiar local conditions of tem- 
perature, currents, or geological substratum, have made the 
North Atlantica perfect vivarium for the calcareous forms. 

“The chart’ you send is very interesting, and combines 
a wonderful amount of interesting phenomena. I have 
little doubt that the history of the bottom of the ocean, 
as recorded by the sediments, would show a close relation 
to the facts determined for the surface, besides many 
unexpected relations. J am very anxious to get some 
soundings from the great ocean current that, as shown in 
your chart, sweeps in through the Caribbean Sea and 
along the coast of Mexico and Texas. 


CHAPTER 
XI. 


§ 754 
Specimens 
different 
from those 
of the 
Atlantic. 


§ 755 
Reference 


to Plate 
10.4 


“T observe on your chart something which looks like § 756 


1 Plate IX. 
By! 


CHAPTER 
XIII. 


Sargasso 
Beas. 


§ 757 
Division of 
labour 
among 
animal- 
cule. 


§ 758 
Specimens 
obtained 
from a 
depth of 
2700 
fathoms. 


$2, THE PHYSICAL GEOGRAPHY OF THE SEA. 


a sargasso sea south-east of Madagascar. Is it su? Get 
soundings, if possible, in these sargasso seas. Get sound- 
ings anywhere—everywhere. Even when they yield 
nothing, the negative fact is of value.” ; 

Here, again, we perceive these little conservators of the 
sea at work. This specimen that Brooke has obtained for 
us comes from the coral regions, and the task of secreting 
the calcareous matter from the sea water appears to have 
been left by these little mites of creatures* to the madre- 
pore and shell-fish, while these mites themselves under- 
took the hard task of getting the silicious matter out. 
The division of labour among the organisms of the sea 
is wonderful. It is a great work-shop, in which the 
machinery is so perfect that nothing ever goes wrong. 

Specimens of the “ooze and bottom of the sea” have 
also been obtained by the ingenuity of Brooke from the 
depth of 2700 fathoms in the North Pacific, and ex- 
amined by Professor Bailey.+ 


* Mauvry’s Sailing Directions, Seventh Edition, p. 155. 

+ “West Pornt, N. Y., January 29, 1856. 

“My Dear Sir,—I have examined with mucli pleasure the highly interesting 
specimens collected by Lieutenant Brooke, of the United States Navy, which you 
kindly sent me for microscopic analysis, and I will now briefly report to you the 
results of general interest which I have obtained, leaving the enumeration of the 
organic contents and the description of new species for a more complete account, 
which I hope soon to publish. The specimens examined by me were as follows, 
namely :— 

“No. 1. Sea bottom, 2700 fathoms ; lat. 56° 46’ N., long. 168° 18’ E. ; brought 
up July 19, 1855, by Lieutenant Brooke, with Brooke’s lead. 

“No. 2. Sea bottom, 1700 fathoms ; lat. 60° 15’ N., long. 170° 53’ E. ; brought 
up as above, July 26, 1855. 

“No. 3. Sea bottom, 900 fathoms ; temperature (deep sea), 82°, Saxton; lat. 
60° 30’ N., long. 175° E. 

“A careful study of the above specimens gave the following results :-— 

“st. All the specimens contain some mineral matter, which diminishes in 
proportion to the depth, and which consists of minute angular particles of quartz, 
hornblend, felspar, and mica. 

“2d. In the deepest soundings (No. 1 and No. 2) there is the least mineral 


THE BASIN OF THE ATLANTIC. S20 


We have now had specimens from the bottom of “ blue 
water” in the narrow Coral Sea, the broad Pacific, and 
the long Atlantic, and they all tell the same story, namely, 
that the bed of the ocean is a vast cemetery. The ocean’s 
bed has been found everywhere, wherever Brooke’s sound- 


matter, the organic contents, which are the same in all, predominating, while the 
reverse is true of No. 3. 

“3d. All these specimens are very rich in the silicious shells of the Diatomacez, 
which are in an admirable state of preservation, frequently wath the valves united, 
and even retaining the remains of the sof: par ts. 

“Ath, Among ne Diatoms the most conspicuous forms are the large and beau- 
tiful discs of several species of Coscinodiscus. There is also, besides many others, 
a large number of a new species of Rhizosolenia, a new Syndendrium, a curious 
species of Chzetoceros, with furcate horns, and a beautiful species of Asterom- 
phalus, which I propose to call Asteromphalus Brookei, in honour of Lieutenant 
Brooke, to whose ingenious device for obtaining deep soundings, and to whose 
industry and zeal in using it, we are indebted for these and many other treasures 
of the deep. 

“Sth. The specimens contain a considerable number of silicious spicules of 
sponges, and of the beautiful silicious shells of the Polycistinee. Among the 
latter I have noticed Cornutella Clathrata of Ehrenberg, a form occurring fre- 
quently in the Atlantic soundings. I have also noticed in all these soundings, 
and shall hereafter describe and figure, several species of Eucyrtidium, Hali- 
calyptra, a Perichlarmidium, a Stylodictya, and many others. 

“6th. Ihave not been able to detect even a fragment of any of the calcareous 
shells of the Polythalamia. This is remarkable, from the striking contrast it 
presents to the deep soundings of the Atlantic, which are chietly made up of 
these calcareous forms. This difference cannot be due to temperature, as it is 
well known that Polythalamia are abundant in the Arctic Seas. 

“7th, These deposits of microscopic organisins, in their richness, extent, and 
the high latitudes at which they occur, resemble those of the Antarctic regions, 
whose existence has been proved by Ehrenberg, and the occurrence in these 
northern soundings of species of Asteromphalus and Cheetoceros is another strik- 
ing point of resemblance. These genera, however, are not exclusively polar forms, 
but, as IT have recently determined, occur also in the Gulf of Mexico and along 
the Gulf Stream. 

“8th. The perfect condition of the organisms in these soundings, and the fact 
that some of them retain their soft portions, indicate that they were very recently 
in a living condition ; but it does not follow that they were living when collected 
at such immense depths. As among them are forms which are known to live 
along the shores as parasites upon the Algex, &c., it is certain that a portion, at 
least, have been carried by oceanic currents, by drift ice, by animals which have 
fed upon them, or by other agents, to their present position. It is hence pro- 
bable that all were removed from shallower waters in which they once lived. 
These forms are so minute, and would float so far when buoyed up by the gases 
evolved during decomposition, that there would be nothing surprising in finding 


CHAPTER 
xiil. 


§ 759 
Specimens 
all tell the 
same 
story. 


8324 THE PHYSICAL GEOGRAPHY OF THE SEA. 


cnaprer ing-rod has touched, to be soft, consisting almost entirely 
XIII. ° . . . 
: of the remains of infusoria. The Gulf Stream has literally 
Gul 
Stream. strewed the bottom of the Atlantic with these microscopic 


shells ; for the Coast Survey has caught up the same in- 
fusoria in the Gulf of Mexico and at the bottom of the 
Gulf Stream off the shores of the Carolinas, that Brooke’s 
apparatus brought up from the bottom of the Atlantic off 

the Irish coast. 
§760 The unabraded appearance of these shells, and the 
Perfect re- almost total absence of the mixture of any detritus from 


pose at the 
bottom of the sea or foreign matter, suggest most forcibly the idea 


fo) 
me of perfect repose at the bottom of the deep sea. 

§761 Some of the specimens that Brooke’s apparatus has 
brought up are as pure and as free from the sand of the 
sea as the snow-flake that falls, when it is calm, upon the 
lea, is from the dust of the earth. Indeed, these sound- 
ings suggest the idea that the sea, like the snow-cloud 
with its flakes in a calm, is always letting fall upon its 

showers of hed showers of these microscopic shells; and then we 


shells.  yeadily imagine that the “sunless wrecks,” which strew 
its bottom, are, in the process of ages, hid under this 


them in any part of the ocean, even if they were not transported, as it is certain 
they often are, by the agents above referred to. 

“9th. In conclusion, it is to be hoped that the example set by Lieutenant 
Brooke will be followed by others, and that, in all attempts to make deep sound- 
ings, the effort to bring up a portion of the bottom will be made. The soundings 
from any part of the ocean are sure to yield something of interest to the micro- 
scopic analysis, and it is as yet impossible to tell what important results may flow 
from their study 

“The above is only a preliminary notice of the soundings referred to. I shall 
proceed without delay to describe and figure the highly interesting and novel 
forms which I have detected, and I hope soon to have them ready for publication. 

“‘ Yours, very respectfull 
en ee a “J. W. Barrey. 
“LIEUTENANT M. F. Mary, 
“ National Observatory, Washington City, D. C.” 


THE BASIN OF THE ATLANTIC. 325 


fleecy covering, presenting the rounded appearance which cnaptss 
. “i XIII. 
is seen over the body of the traveller who. has perished 


. . - 2 How, and 
in the snow-storm. The ocean, especially within and near with’ wnat 


. . : . . 5 the bottom 
the tropics, swarms with life. The remains of its myriads ortne 


ocean is 
covered. 


of moving things are conveyed by currents, and scattered 
and lodged in the course of time all over its bottom. This 
process, continued for ages, has covered the depths of the 
ocean as with a mantle, consisting of organisms as deli- 
cate as the macled frost, and as light as the undrifted 
snow-flake on the mountain! 


1 § 1025. 


326 THE PHYSICAL GEOGRAPHY OF THE SEA. 


CHAPTER XIV. 
THE WINDS. 


Belt of South-east broader than North-east, § 764.—Tracks of Vessels across the 
South-east Trades, 767.—Scenes in the Trade-wind Regions, 770.—The Effect 
of South Africa and America upon the Winds, 779.—Monsoons, 787.—Dove’s 
Theory, 789.—Proof that the South-west Monsoons are the South-east Trades 
deflected, 797.—How the South-west Monsoons march toward the Equator, 806. 
—How the Monsoon Season may be known, 809.—Influence of Deserts upon the 
Winds, 810.—Changing of the Monsoons, 819.—West Monsoon in Java Sea, 823 
—Water-spouts, 826.—Influence of Currents upon Winds, 829.—The Calm 
Belts, 835.—The Equatorial Calms, 837.—The Horse Latitudes, 840.—The 
Westerly Winds, 843.—The brave West Winds of the Southern Hemisphere, 846. 


cnarpreR PLATE VIII. is a chart of the winds, based on information 
= derived from the Pilot Charts, one of the series of Maury’s 
» 762 Wind and Current Charts. The object of this chart is to 
make the student acquainted with the prevailing direction 

of the wind in every part of the ocean. 

The arrows of the plate are supposed to fly with the 
wind; the half-bearded and half-feathered arrows denoting 
monsoons or periodic winds; the dotted bands, the regions 
of calm and baffling winds. 

ee Monsoons, properly speaking, are winds which blow 
one half of the year from one direction, and the other 
half from an opposite, or nearly an opposite direction. 

Let us commence the study of Plate VIII. by examin- 
ing the trade-wind region; that, also, is the region in 
which monsoons are most apt to be found. 

$764 The belt or zone of the south-east trade-winds is 
zoneof broader than the belt or zone of north-east trades. This 


south-east 


tade- phenomenon is explained by the fact that there is more 
broader land in the northern hemisphere, and that most of the 
lan 

north-east. deserts of the earth—as the great deserts of Asia and 


Africa 


are situated in the rear, or behind the north-east 


THE WINDS. 327. 


trades; so that, as these deserts become more or less ciaprex 
. . . XIV. 
heated, there is a call—a pulling back, if you please— 


upon these trades to turn about and restore the equili- 
brium which the deserts destroy. There being few or no 
such regions in the rear of the south-east trades, the 
south-east trade-wind force prevails, and carries them over 
into the northern hemisphere. 

By resolving the forces which it is supposed are the § 765 
principal forces that put these winds in motion, namely, ‘he forces 
calorific action of the sun and diurnal rotation of the Sn 
earth, we are led to the conclusion that the latter is much og 
the greater of the two in its effects upon those of the 
northern hemisphere. But not to such an extent is it 
greater in its effects upon those of the southern. We 
see by the plate that those two opposing currents of eae 
wind are so unequally balanced that the one recedes balance 
before the other, and that the current from the southern 
hemisphere is larger in volume; 7. e., it moves a greater 
zone or belt of air. The south-east trade-winds dis- 
charge themselves over the equator —v. €., across a 
great circle—into the region of equatorial calms; while 
the north-east trade-winds discharge themselves into the 
same region over a parallel of latitude, and consequently 
over a small circle. If, therefore, we take what obtains 
in the Atlantic as the type of what obtains entirely 
around the earth, as it regards the trade-winds, we shall 
see that the south-east, trade-winds keep in motion more South-east 
air than the north-east do, by a quantity at least propor- gerne 
tioned to the difference between the circumference of the 
earth at the equator and at the parallel of latitude of 9° 
north. For if we suppose that these two perpetual cur- 
rents of air extend the same distance from the surface of 
the earth, and move with the same velocity, a greater 


328 THE PHYSICAL GEOGRAPHY OF THE SEA. 


carter Volume from the south would flow across the equator in 
aE given time than would flow from the north over the 
parallel of 9° in the same time; the ratio between the 

two quantities would be as radius to the secant of 9° 
Besides this, the quantity of land lying within and to the 

north of the region of the north-east trade-winds is much 
greater than the quantity within and to the south of the 

region of the south-east trade-winds. In consequence of 

this, the mean level of the earth’s surface within the 
region of the north-east trade-winds is, it may reasonably 

be supposed, somewhat above the mean level of that part 

which is within the region of the south-east trade-winds. 

Ovstrucee And as the north-east trade-winds blow under the influ- 


tions to 
north-east ence of a greater extent of land surface than the south- 


cat east trades do, the former are more obstructed in their 

course than the latter, by the forests, the mountain 

ranges, unequally: heated surfaces, and other such like in- 
equalities. 

§766 As already stated, the investigations show that the 

Effect of momentum of the south-east trade-winds is sufficient to 


momen- 


oan push the equatorial limits of their northern congeners 
trades. back into the northern hemisphere, and to keep them, at 
a mean, as far north as the ninth parallel of north lati- 
tude. Besides this fact, they also indicate that while the 
north-east trade-winds, so called, make an angle in their 
general course of about 23° with the equator (east-north- 
east), those of the south-east make an angle of 30° or 
more with the equator (south-east by east),—I speak of 
those in the Atlantic ;—thus indicating that the latter 
approach the equator more directly in their course than 
South-east do the others, and that, consequently, the effect of the 
fesher diurnal rotation of the earth being the same for like 


than 


north-east. parallels north and south, the ealorific influence of the 


THE WINDS. 829 


sun exerts more power in giving motion to the southern cuyapree 
. . . XIV. 
than to the northern system of Atlantic trade-winds ; in 


other words, the south-east trade-winds are, on the aver- 
age, fresher than the north-east. 

The south-east trade-winds of the Atlantic, particularly § 767 
in our summer and autumn months, haul more and more 


toward the south as they approach the equator. The 


Tracks of 
vessels to 


tracks of vessels bound to India from Europe show this 
in a very striking manner. They cross the equator Ml 
generally about the meridian of 20° west; there they 
find the wind from south-east, frequently from south- 
south-east, which forces the vessel off upon a course west 
of south. As the vessel gets south, the winds haul more 
and more to the east, so that, before clearing the belt of 
the south-east trades, the India-bound trader is steering 
to the east of south. 

That the land of the northern hemisphere does assist $ 768 


to turn these winds, is rendered still more probable from 4"! 

this circumstance : All the great deserts are in the northern aoe 

hemisphere, and the land-surface is also much greater on 2ssists te 
y 2) turn thesa 


our side of the equator. The action of the sun upon winds 
these unequally-absorbing and radiating surfaces in and 
behind, or to the northward, of the north-east trades, 
tends to check these winds, and to draw in large volumes 
of the atmosphere, that otherwise would be moved by 
them, to supply the partial vacuum made by the heat of 
the sun, as it pours down its rays upon the vast plains of 
burning sands and unequally heated land-surfaces in our 
overheated hemisphere. The north-west winds of the 
southern are also, it may be inferred, stronger than the 
south-west winds of the northern hemisphere. 

“A ship leaving the English Channel to go to the § 769 
equator generally aims,” says Jansen, “to come too soon 


CHAPTER 
XIV. 


Jansen’s 
remarks 
on ships 
and winds. 


§ 770 
Dutch 
shipssteer- 
ing for 
Cape Verd 
Islands. 


Beauties of 
the sea. 


5 


9 


530 THE PHYSICAL GEOGRAPHY OF THE SEA. 


& 


into the north-east trade. The winds which prevail most, 
northward of the calm belt of Cancer, are the south-west. 
Wind and weather, in this part of the Atlantic Ocean, 
are very unreliable and changeable; nevertheless, in the 
summer months, we find permanent north winds along 
the coast of Portugal. These north winds are worthy of 
attention, the more so from the fact that they occur 
simultaneously with the African monsoon, and because 
we then find northerly winds also in the Mediterranean, 
and in the Red Sea, and farther eastward to the north 
of the Indian monsoon. 

“When, between the months of May and November, 
during which the African monsoon prevails, the Dutch 
ships, which have lingered in the calm belt of Cancer, run 
with the north-east trade and direct their course for the 
Cape Verd Islands, then it seems as if they were in 
another world. The sombre skies and changeable— 
alternately chilly and sultry—weather of our latitudes 
are replaced by a regular temperature and good settled 
weather. Each one rejoices in the glorious heavens, in 
which none save the little trade-clouds are to be seen; 
which clouds in the trade-wind region make the sunset 
so enchanting. The dark blue water, in which many 
and strange kinds of echinas sport in the sunlight, and, 
when seen at a distance, make the sea appear like one 
vast field adorned with flowers; the regular swellings of 
the waves with their silvery foam, through which the 
flying-fishes flutter; the beautifully-coloured dolphins ; 
the diving schools of tunnies ;—all these banish afar the 
monotony of the sea,* awake the love of life in the youth- 


* When we, as our forefathers did, preserve in the journals all that we observe 
at sea, then we shall have abundant material with which to keep ourselves 
pleasantly oceupied. 


THE WINDS. sol 


ful seaman, and attune his heart to goodness. Every- 
thing around him fixes his attention and increases his 
astonishment. 

“Tf all the outbreathings of heartfelt emotion which 
the contemplation of nature forces from the sailor were 
recorded in the log-books, how much farther should we 
be advanced in the knowledge of the natural state of the 
sea! Once wandering over the ocean, he begins to be 
impressed, by the grand natural tableau around him, with 
feelings deep and abiding. The most splendid forecastle 
is lost in the viewless surface, and brings home to us the 
knowledge of our nothingness; the greatest ship is a 
plaything for the billows, and the slender keel seems to 
threaten our existence every moment. . But when the 
eye of the mind is permitted to wander through space 
and into the depths of the ocean, and is able to form a 
conception of Infinity and of Omnipotence, then it knows 
no danger; it is elevated—it comprehends itself. The 
distances of the heavenly bodies are correctly estimated ; 
and, enlightened by astronomy, with the aid of the art of 
navigation, of which Maury’s Wind and Current Charts 
form an important part, the shipmaster marks out his 
way over the ocean just as securely as any one can over 
an extended heath. He directs his course toward the 
Cape Verd Islands, and is carried there by the lively 
trade-wind. Yet beyond the islands, sooner or later, 
according to what month it is, the clear skies begin to be 
clouded, the trade-wind abates and becomes unsteady, the 
clouds heap up, the thunder is heard, heavy rains fall ; 
finally, the stillness is death-like, and we have entered 
the belt of calms. This belt moves toward the north 
from May to September. It is a remarkable phenomenon 
that the annual movements of the trades and calm belts 


CHAPTER 
XIY. 


Stir 
Refiec- 
tions on 
ocean 8 
grandeur. 


The sail- 
or’s cer- 
tainty in 
traversing 
the sea. 


The belt of 
culms. 


Sor THE PHYSICAL GEOGRAPHY OF THE SEA. 


oxapter from south to north, and back again, do not directly follow 
**' the sun in its declination, but appear to wait until the 


temperature of the sea water puts it in motion. The 
trades and the belt of calms do not decline before the 
temperature of 80° of the water in the North Atlantic 
Ocean turns it southward; and in the spring they do not 
go northward until the temperature of 80° returns it 
atmo nq thence. Is it not as if the atmosphere and the ocean 


sphereand 


ocean’ __ were united in marriage, and go hand in hand to stand 
united in f=) 


marriage. by and to care for each other, so that they may fulfil all 
their duties together ? 
$772 “Tf a ship which has come into the belt of calms, 


Move- 
ments of 
the belt of 
calms. 


between May and September, can he still in the place 
where it came into this belt,—cast anchor, for example,— 
then it would perceive a turning of the monsoon or of the 
trade-wind. It would see the belt of calms draw away 
to the north, and afterward get the south-west monsoon, 
or, standing more westerly, perhaps the south-east trade. 
On the contrary, later than September, this ship lying at 
anchor will see the north-east gradually awake. The 
belt of calms then moves toward the south, and removes 
from the ship, which remains there anchored on the north 
side.’* 

§773 ‘The investigations that have taken place at the Observa- 
Influence tory show that the influence of the land upon the normal 


of land on 


See directions of the wind at sea is an immense influence. 
at winds, 


It is frequently traced for a thousand miles or more out 
upon the ocean. For instance, the action of the sun’s 


rays upon the great deserts and arid plains of Africa, in 


* Natuurkiindige Beschrijving der zeeén, door M. F. Maury, LL.D., Luitenant 
der Nord-Amerikaansche Marine, vertaald door M. H. Jansen, Luitenant dez 
Zee (Bijdrage). Dordrecht, P. K. Braat. 1855 


THE WINDS. 313 }8) 


the summer and autumnal months, is such as to be feit 
nearly across the Atlantic Ocean between the equator and 
the parallel of 13° north. Between this parallel and the 
equator, the north-east trade-winds, during these seasons, 
are arrested in their course by the heated plains of Africa ; 
instead of “blowing home” to the equator, they stop and 
ascend over the desert sands of the continent. The south- 
east trade-winds, arriving at the equator during this 
period, and finding no north-east trades there to contest 
their crossing the line, continue their course, and blow 
home as a south-west monsoon to the deserts where they 
ascend. These southwardly monsoons bring the rains 
which divide the seasons in these parts of the African 
coast. The region of the ocean embraced by these mon- 
soons is cuneiform in its shape, having its base resting 
upon Africa, and its apex stretching over till within 10° 
or 15° of the mouth of the Amazon. 

Indeed, when we come to study the effects of South 
America and Africa (as developed by the Wind and Cur- 
rent Charts) upon the winds at sea, we should be led to 
the conclusion, had the foot of civilized man never trod 
the interior of these two continents, that the climate of 
one is humid,—that its valleys are, for the most part, 
covered with vegetation, which protects its surface from 
the sun’s rays; while the plains of the other are arid and 
naked, and, for the most part, act like furnaces in drawing 
the winds from the sea to supply air for the ascending 
columns which rise from its over-heated plains. 

Pushing these facts and arguments still farther, these 
beautiful and interesting researches seem already sufficient 
almost to justify the assertion, that, were it not for the 
Great Desert of Sahara and other arid plains of Africa, 


CHAPTER 
XIV. 


Monsoons 


§ 774 
Effects of 
South 
America 
and Africa 
on winds 
at sea. 


§.775 
Effects of 
Great 
Desert of 
Sahara, &e 


354 THE PHYSICAL GEOGRAPHY OF THE SEA. 


cuaprer the western shores of that continent, within the trade- 
as owind region, would be almost, if not altogether, as rainless 
and sterile as the desert itself. 

§776 Lieutenant Jansen has called my attention to a vein 
A yemark- of wind which forms a current in the air as remarkable 
rentofair. as that of the Gulf Stream is in the sea. This atmosphe- 

rical Gulf Stream is in the south-east trade-winds of the 
Atlantic. It extends from near the Cape of Good Hope 
in a direct line to the equator, on the meridian of Cape 
St. Roque." The homeward route from the Cape of Good 
Hope lies in the middle of this vein; in it the winds are 
more steady than in any other part of the Atlantic On 
the edges of this remarkable aerial current the wind is 
variable, and often fitful. The homeward-bound Indiaman 
resorts to and uses this stream in the atmosphere as the 
European-bound American does the Gulf Stream. It is 
shaded on the plate. 


§777 These investigations, with their beautiful developments, 
Value of 
arid de- 


serts ane ation, they teach us to regard the sandy deserts and arid 


sandy 


plains. plains, and the inland basins of the earth as compensa- 


eagerly captivate the mind; giving wings to the imagin- 


tions in the great,system of atmospherical circulation. 
Like counterpoises to the telescope, which the ignorant 
regard as encumbrances to the instrument, these wastes 
serve as make-weights, to give certainty and smoothness 
of motion, facility and accuracy to the workings of the 
machine. 

$778 When we travel out upon the ocean, and get beyond 


The ocean . - 

the best the influence of the land upon the winds, we find our- 
field for . P q 
ovserving Selves in a field particularly favourable for studying the 
aerial plie- 2 3 ‘ 

nomena general laws of atmospherical circulation. Here, beyond 


And laws. 


EEN 


1 Plate VIIL. 


THE WINDS. ra) 


the reach of the great equatorial and polar currents of 
the sea, there are no unduly-heated surfaces, no mountain 
ranges, or other obstructions to the circulation of the 
atmosphere,—nothing to disturb it in its natural courses. 
The sea, therefore, is the field for observing the opera- 
tions of the general laws which govern the movements of 
the great aerial ocean. Observations on the land will 
enable us to discover the exceptions, but from the sea we 
shall get the rule. Each valley, every mountain range 
and local district, may be said to have its own peculiar 
system of calms, winds, rains, and droughts. But not so 
the surface of the broad ocean ; over it the agents which 
are at work are of a uniform character. 

RAIN-WINDS are the winds which convey the vapour 
from the sea, where it is taken up, to other parts of the 
earth, where it is let down, either as snow, hail, or rain. 
As a general rule, the trade-winds may be regarded as 
the evaporating winds ; and when, in the course of their 
circuit, they are converted into monsoons, or the variables 
of either hemisphere, they then generally become also the 
rain-winds—especially the nionsoons—for certain locali- 
ties. Thus the south-west monsoons of the Indian Ocean 
are the rain-winds for the west coast of Hindostan.* In 
like manner the African monsoons of the Atlantic are the 
winds which feed the springs of the Niger and the Senegal 
with rains. 

Upon every water-shed which is drained into the sea, 
the precipitation, for the whole extent of the shed so 
drained, may be considered as greater than the evapora- 
tion by the amount of water which runs off through the 
river into the sea. In this view, all rivers may be 


1 ¢ 202. 


CHAPTER 
xXIy. 


§ lordard 
dic 
Rain- 
winds. 


§ 780 


Precipita- 
tion com- 
pared with 
evapora- 
tion, 


CHAPTER 
XIV. 


§ 781 
The 
sourees 
whence 
the Ama- 
zon and 
Mississippi 
get their 
water. 


336 THE PHYSICAL GEOGRAPHY OF THE SEA. 


regarded as immense rain-gauges, and the volume of 
water annually discharged by any one as an expression 
of the quantity which is annually evaporated from the 
sea, carried back by the winds, and precipitated through- 
out the whole extent of the valley that is drained by it. 
Now, if we knew the rain-winds from the dry for each 
locality and season generally throughout such a basin, we 
should be enabled to determine, with some degree of pro- 
bability at least, as to the part of the ocean from which 
such rains were evaporated. And thus, notwithstanding 
all the eddies caused by mountain chains and other un- 
even surfaces, we might detect the general course of the 
atmospherical circulation over the land as well as the sea, 
and make the general courses of circulation in each valley 
as obvious to the mind of the philosopher as is the cur- 
rent of the Mississippi, or of any other great river, to his 
senses. . 

These investigations as to the rain-winds at sea indi- 
cate that the vapours which supply the sources of the 
Amazon with rain are taken up from the Atlantic Ocean 
by the north-east and south-east trade-winds ; and many 
circumstances, some of which have already been detailed; 
tend to show that the winds which feed the Mississippi 
with rains get their vapour in the south-east trade-wind 
region of the other hemisphere. For instance, we know 
from observation that the trade-wind regions of the ocean, 
beyond the immediate vicinity of the land, are, for the 
most part, rainless regions; and that the trade-wind 
zones may be described, in a hyetographic sense, as the 
evaporating regions, They also show, or rather indicate, 
as a general rule, that, leaving the polar limits of the two 


THE WINDS. 35 


trade-wind systems, and approaching the nearest pole, the 
precipitation is greater than the evaporation until the 
point of maximum cold is reached. 

And we know also that, as a general rule, the south- 
east and north-east trade-winds, which come from a lower 
and go to a higher temperature, are the evaporating 
winds,—7.¢., they evaporate more than they precipitate ; 
while those winds which come from a higher and go to a 
lower temperature are the rain-winds,—. e., they precipi- 
tate more than they evaporate. That such is the case, 
not only do researches indicate, but reason teaches and 
philosophy intimates. 

These views, therefore, suggest the inquiry as to the 


CHAPTER 
XIV. 


§ 782 


South-east 
and north- 
east trade- 
winds are 
evaporat- 
ing winds. 


§ 783 


sufficiency of the Atlantic, after supplying the sources of Query re- 


the Amazon and its tributaries with their waters, to sup- 
ply also the sources of the Mississippi and the St. Law- 
rence, and of all the rivers, great and small, of North 
America and Europe. 

A careful study of the rain-winds, in connection with 
the Wind and Current Charts, will probably indicate to 
us the “springs in the ocean” which supply the vapours 
for the rains that are carried off by those great rivers. 
‘All the rivers run into the sea, yet the sea is not full; 
unto the place from whence the rivers come, thither they 
return again.” 

Mownsoons’ are, for the most part, formed of trade- 
winds. When, at stated seasons of the year, a trade-wind 
is deflected in its regular course from one quadrant to an- 
other, or drawn in by over-heated districts, it is regarded 
as a monsoon. Thus the African monsoons of the Atlan- 
tic, the monsoons of the Gulf of Mexico, and the Central 


1 £32, 2 § 763. 3 Plate VIII. 
22 


garding 
the Atlan- 
tic. 


§ 786 


Springs in 
the ocean. 


§ 787 


Monsoons 


CHAPTER 
XIy. 


§ 788 


Monsoons 
of the 
Indian 
Ocean. 


§ 789 


Dove's 
opinion, 


§ 790 


338 THE PHYSICAL GEOGRAPHY OF THE SEA. 


American monsoons of the Pacific, are, for the most part, 
formed of the trade-winds, which are turned back or de- 
flected to restore the equilibrium which the over-heated 
plains of Africa, Utah, Texas, and New Mexico, have dis- 
turbed. When the monsoons prevail for five months at 
a time—for it takes about a month for them to change 
and become settled—then both they and the trade-winds, 
which they replace, are called monsoons. 

The north-east and the south-west monsoons of the 
Indian Ocean afford an example of this kind. A force is 
exerted upon the north-east trade-winds of that sea by 
the disturbance which the heat of summer creates in the 
atmosphere over the interior plains of Asia, which is more 
than sufficient to neutralize the forces which cause those 
winds to blow as trade-winds ; it arrests them, and were 
it not for the peculiar conditions of the land about that 
ocean, what are now called the north-east monsoons would 
blow the year round. There would be no south-west 
monsoons there; and the north-east winds, being per- 
petual, would become all the year what in reality for 
several months they are, namely, north-east trade-winds. 

As long ago as 1831, Dove* maintained that the 
south-west monsoon was the south-east trade-wind rush- 
ing forward to fill the vacant places over the northern 
deserts. Dove admits the proofs of this to be indirect, 
and acknowledges the difficulty of finding out and de- 
monstrating the problem.-+ 

I had been studying the wind in his circuits, and 


* Vide Poaa, Ann. xxi. 
+ Annalen der Physik, No. 94. Translated by Dr. Rosengarten for the 
American Journal of Science, vol. xx., No. 60. 


THE WINDS. 339 


hundreds of sailors were watching the vane for me ; and omaprzr 
my good friend Jansen encouraged me, by his reasoning ae 
and suggestions, to undertake the task of proving this 
difficult proposition of Mr. Dove. 

The north-east and south-east trade-winds meet, we g§ 791 
know, near the equator, where they produce’ the belt of Bett of 
equatorial calms. All vessels that pass from one system cae 
of trade-winds to the other have to cross this calm belt. 
Sometimes they clear it in a few hours, sometimes they 
are delayed in it for weeks; and the calm is so still, and 
the rain so copious, that the fresh water is sometimes 
found standing in pools on the sea. 

If it be true, as Dove maintains, that the south-west § 792 
monsoons of the Indian Ocean are the south-east trade- cena 
winds of that sea pressing up toward the desert regions opinion. 
of Asia, then a vessel bound hence to Calcutta, for in- 
stance, and entering the Indian Ocean at the time of the 
south-west monsoon, should find no belt of equatorial 
calms there at all, but, on the contrary, she should find 
the south-east trade-wind to haul more and more to the 
south, until finally, without having crossed any belt of 
equatorial calms, she would find her sails trimmed to the 
south-west monsoon. 

In like manner, Jansen maintains that the north-west § 793 
monsoon is a similar deflection of the north-east trade- Jansen’s 
wind. cae 

I had many log-books relating to the Indian Ocean, § 794 
and I had already, at the commencement of my labours Frets: 
on the Wind and Current Charts, essayed an examination sation. 
into the monsoons of the Indian Ocean; but the mate- 


rials on hand at that time proved insufficient. They 


1 g 122. 2 § 162, 


CHAPTER 
XIV. 


§ 790 


Result. 


§ 796 


Causes of 
the mon- 
soons. 


340 THE PHYSICAL GEOGRAPHY OF THE SEA. 


have been accumulating ever since; and though not yet 
ample enough to settle definitively such a question, they 
are, nevertheless, sufficient to throw some valuable and 
certain light upon the subject. Encouraged by Jansen, 
and the number of log-books, I have recently put the 
materials in the hands of Lieutenant West for co-ordina- 
tion. 

The result is, they GIVE NO INDICATION of ANY cali 
belt between the south-east trade-wind and the south-west 
monsoon of the Indian Ocean. 

The Desert of Cobi and the arid wastes of Asia‘are the 
causes of these monsoons. When the sun is north of the 
equator, the force of his rays, beating down upon these 
wide and thirsty plains, is such as to cause the vast 
superincumbent body of air to expand and ascend. Con- 
sequently, there is an indraught of air from the surround- 
ing regions to supply the ascending column. The air 
that is going to feed the north-east trades is thus arrested, 
drawn in, heated, and caused to ascend; and so, the 
north-east trade-winds are first weakened, then “ killed,” 
and afterward drawn into the vortex of ascending air 
over the burning sands of the deserts. On the other 
hand, the south-east trade-wind, failing, when it arrives 
at the place where the equatorial Doldrums were wont to 
be, to meet with them or any opposing force. from the 
north-east trades, are drawn over into the northern hemi- 
sphere. Going now from the equator toward the poles, 
their tendency is*to obey the forces of diurnal rotation, as 
well as those of the indraught for the heated plains; and 
thus the south-east trades become south-west monsoans. 
In this view, the “equatorial Doldrums” of the Indian 


1 § 202, 2 § 126, 


THE WINDS. 341 


Ocean are transferred, as it were, during the south-west 
monsoons, to the deserts of Central Asia. 

It may be asked by some saying, Since we cannot 
always tally the air, how do we know that these south- 
west monsoons are the south-east trades of the Indian 
Ocean? The reply is, We infer that they are, because, in 
co-ordinating for the Pilot Chart of that sea, we have 
found’ no belt of calms between the south-east trades and 
the south-west monsoons, but a gradual change, so to 
speak, of the one wind into the other. Thus, confining 
ourselves to August,—one of the south-west monsoon 
months,—and to the strip of ocean between 85° and 90° 
east, the investigation gives as follows for calms and 
winds in the field between— 

10° S. and 5° S. 133 observations. (calms. Wind S.E. 
5: S. and 0°, | 102 3 8 


0° and 6° N. 99 See. aa Sane 
5° N. and 10° N. 77 2 OMS nap SBA 

These monsoons do not, as we are generally taught to 
suppose, commence or end at the same time all over the 
Indian Ocean. 

The Pilot Charts (Plate V.) have brought this fact 
out in very bold relief. Take, as an illustration, the 
strip of ocean between the meridians of 85° and 90° east, 
south of Calcutta, and as far as the equator. Let us 
divide it into “fields” (Plate V.), by drawing across it 
lines to represent the parallels of 5°, 10°, 15°, and 20° 
north. 

In the first “field” below Calcutta,—7. e., between the 
land and 20° north,—the north-east trade-winds, toward 
the latter part of January, begin their conflict with the 
south-west monsoons. The conflict rages in February, 


CHAPTER 
XIV. 


§ 797 


Reply to 
objection. 


§ 798 


§ 799 
Pilot 
Charts. 


§ 800 


References 
to Plate V. 


CHAPTER 
XIV. 


Causesand 
courses of 
monsoons 
and trade- 
winds. 


§ 801 


The same 
continued. 


$ 802 


Os 


42 THE PHYSICAL GEOGRAPHY OF THE SEA. 


and by March the south-west monsoons in that “field” 
are considered to have regularly set in, They now re- 
main the dominant wind for upwards of six months, 
until some time in the early part of September. The 
north-east monsoons or trades now renew the conflict, 
which is carried on with more and more vigour until the 
latter part of November, when they obtain the ascend- 
ency, and prevail until the latter part of January, when, 
as before stated, the south-west monsoons commence their 
annual struggle for the mastery. 

In the next “field” below,—. e., between 15° and 20° 
north latitude,—the north-east monsoons begin to grow 
light and variable, and to have conflicts with the south- 
west in February. The period of this conflict, or change, 
as it is called, frequently lasts until some time in March, 
when the force that is calling in and driving the mon- 
soons from the south-west finally gains the ascendant. 
They then blow steadily until late in September, when 
the north-east trade-wind forces begin again to assert 
their ascendency, and to renew the conflict on this side 
through October, by which time the north-east trades or 
monsoons become the prevailing winds. ‘Thus, by going 
two or three hundred miles farther from the supposed 
place of heat and rarefaction that give rise to this system 
of winds, the duration of the north-east monsoons is pro- 
longed nearly a month: for in this “ field” they prevail 
from November to January inclusive, three months; while 
the south-west last from about the middle of March to 
the middle of September, say six months. 

In the next “field” below,—4. e., between the parallels 
of 10° and 15°,—the south-west monsoons blow about five 


THE WINDS. 343 


months, perhaps not quite so long. They do not com- cnarner 
mence as early, nor blow so late, as in the “ field” above. ane 
They begin the conflict with the north-east trade-wind continuea 
forces in the latter part of March, and gain the ascendant 
in May. They then prevail till October, when the north- 
east trade-wind forces, escaping from the heated plains of 


the interior, begin to renew the annual combat which is 
to get them the victory. They soon achieve it, and main- 
tain the mastery undisputed till the last of March or first 
of April. 

In the next “ field” below,—namely, that between 5° § 803 
and 10° north,—the north-east trades or monsoons do not eee 
begin to feel the heating-up of the deserts until the month 
of April has set in. The battle now, as it may well be 
supposed, is not to last long; for the sun is vigorously at 
work, heating-up the brown wastes, and calling upon the 
north-east trades to stop and supply the ascending column 
with fresh air. By the end of April, the south-west mon- 
soons are found to be decidedly in the ascendant, and they 
so continue for nearly five months. In October, but not 
before the middle, the conflict again commences ; feebly 
at first and by fitful gusts it rages all through November, 
and is not fairly over before the end of December. Here 
signs of the south-east trade-winds begin to appear. They 
come in on the side, now of the north-east, now of the 
south-west monsoons, and so prolong the contest. 

In the next “ field,’-—between 0° and 5° north,—the § 804 
south-west monsoon is decidedly marked only for a short TOS eee 
time. This conflict ends in May; the other begins in 
August, leaving the north-east trade-winds decidedly in 
the ascendant for only about three months,—January to 


S44 THE PHYSICAL GEOGRAPHY OF THE SEA. 


cxapteR March: so that in this “field” we have, during the year, 
~~ six months of conflicting winds, and three months only 
for each monsoon. 
$805 If a ship were stationed in each one of these five 
euDLores “ fields,” to observe the setting in, continuance, and 
epietee: changing of the monsoons, the one in the northern “ field,” 
between the land and 20° north, would report that the 
south-west monsoons had been observed to have regularly 
set in before the first of March, after a conflict which 
lasted perhaps six weeks. The observer in the next 
“field” below—~. e., between 15° and 20° north—would 
report that he found the south-west monsoons to set in 
about the middle of March, and after a conflict that com- 
menced in February, instead of January, as in the “ field” 
above. The vessel in the “field” next below—10° and 
15°—would report them early in May, after a conflict of 
four or five weeks. The ship between 5° and 10° would 
not find them to set in regularly until the first of May; 
and still later would the vessel in the last “ field”—0° 
and 5° north—report them. Thus we perceive that the 
south-west monsoons extend from the land out to the sea 
at a progressive rate, and that they spread from a centre 
Aereniof s08 point like a circle on the water. According to the 
monsoons. Pilot Chart, which gives 11,800 observations for the five 
“fields” above, the march of the south-west monsoons 
from Calcutta toward the equator is at the rate of fifteen 
or twenty miles a day. 
§806 In other words, if a vessel in latitude 23° north, between 
Suppos’t|, the meridians 85° and 90° east, were to commence about 


vessel. the first of March to steer due south, and sailed fifteen or 
twenty miles a day on that course, till she reached the 


THE WINDS. 345 


equator, she would, at the end of each day’s sail, arrive 
with the regular setting in of the south-west monsoons 
at that place. 

We thus perceive how a desert land spreads its influ- 
ence through the distance upon the winds. The first 
effects of heating-up the plains are necessarily felt by the 
air nearest at hand, and by that farther off at a later 
period ; so that the south-west monsoon influence is, in 
this part of the ocean, propagated from the land out upon 
the sea at the rate above stated. 

Of course, the vast plains of Asia are not brought up 
to monsoon heat per saltwm, or in a day. They require 
time, both to be heated up to this point and to be cooled 
down again. 

The monsoon season may be always known by referring 
to the cause which produces these winds. Thus, by recol- 
lecting where the thirsty and over-heated plains are which 
cause the monsoons, we know at once that these winds 
are rushing with greatest force toward these plains at 
the time that is the hottest season of the year upon 
them. 

The influence of these heated plains upon the winds 
at sea is felt for a thousand miles or more. Thus, though 
the Desert of Cobi and the sun-burned plains of Asia 
are, for the most part, north of latitude 30°, their influ- 


CHAPTER 
XIV. 


§ 807 
Influence 


of a desert 
land. 


$ 808 


Plains of 
Asia. 


$ 809 


How the 
monsoon 
seasons 
may be 
known. 


§ 810 


Influence 
of heated 
plains felt 
far out at 
sea. 


. . . 3 
ence in making monsoons’ is felt south of the equator. | 


So, too, with the great Desert of Sahara and the African 
monsoons of the Atlantic; also, with the Salt Lake 
country and the Mexican monsoons on one side, and those 
of Central America in the Pacific on the other. The 
influence*of the deserts of Arabia upon the winds is felt 


IS fe 2 Plate VIII. = § 202. 


CHAPTER 
MV 


§ 811 


Society 
and Sand- 
wich 
Tslands 
have sin- 
gular 
effect on 
winds. 


§ 812 


Influence 
of islands 
on Pacific 
trade- 
winds. 


§ 813 
Clouds on 
the Pacific, 


346 THE PHYSICAL GEOGRAPHY OF THE SEA, 


in Austria and other parts of Europe, as the observations 
of Kriel, Lamont, and others, show. 

So also the islands, such as the Society and Sand- 
wich, that stand far away from any large extent of land, 
have a very singular but marked effect upon the wind. 
They interfere with the trades very often, and turn them 
back ; for westerly and equatorial winds are common at 
both these groups, in their winter time. Some hydro- 
graphers have taken those westerly winds of the Society 
Islands to be an extension of the monsoons of the Indian 
Ocean. Not so: they are local, and do not extend a 
great way either from the Sandwich or Society Islands. 

That they are local about the former group, an examina- 
tion of sheet No. 5, Pilot Chart North Pacific, will instantly 
show. 

It is a curious thing this influence of islands in the 
trade-wind region upon the winds in the Pacific. Every 
navigator who has cruised in those parts of that ocean 
has often turned with wonder and delight to admire the 
gorgeous piles of cumuli, heaped up and arranged in the 
most delicate and exquisitely beautiful masses that it is 
possible for fleecy matter to assume. Not only are these 
piles found capping the hills among the islands, but they 
are often seen to overhang the lowest islet of the tropics, 
and even to stand above coral patches and hidden reefs, 
“a cloud by day,” to serve as a beacon to the lonely 
mariner out there at sea, and to warn him of shoals and 
dangers which no lead nor seaman’s eye has ever seen or 
sounded out. ; 

These clouds, under favourable circumstances, may be 
seen gathering above the low coral island, and performing 
their office in preparing it for vegetation and fruitfulness 
in a very striking manner, As they are condensed into 


THE WINDS. 347 


showers, one fancies that they are a sponge of the most cHarren 
exquisite and delicately-elaborated material, and that he ——~ 
can see, as they “drop down their fatness,” the invisible 

but bountiful hand aloft that is pressing and squeezing it 
out.—Maury’s Sailing Directions, 7th ed., p. 820. 

It would appear, therefore, that these desert countries § 814 
exercise a powerful influence in checking and overcoming No exten- 
the force of the north-east trade-winds. There are no fuenees 
such extensive influences at work checking the south-east south-east 
trades. On the contrary, these are accelerated; for the eth 
same forces that serve to destroy the north-east trade- 
winds, or retard them, tend also to draw the south-east 
trade-winds on, or to accelerate them. Hence the ability 
of the south-east trade-winds to push themselves over into 
the northern hemisphere. 

Hence, also, we infer that, between certain parallels of § 815 
latitude in the northern hemisphere, the sun’s rays, by Méference. 
reason of the great extent of land surface, operate with 
much more intensity than they do between corresponding 
parallels in the southern; and that, consequently, the 
mean summer temperature on shore north of the equator 
is higher than it is south: a beautiful physical fact which 
the winds have revealed, in corroboration of what ob- 
servations with the thermometer had already induced 
meteorologists to suspect. 

It appears, from what has been said, that it is the rays § 816 
of the sun operating upon the land, not upon the water, ae 
which causes the monsoons. Now let us turn to 
Plate VIII., and examine into this view. The mon- 
soon regions are marked with half-bearded and _half- 
feathered arrows; and we perceive, looking at the 
northern hemisphere, that all of Europe, some of Africa, 


most of Asia, and nearly the whole of North America, 


CHAPTER 
XIV. 


§$ 817 


Remarks 
on inter- 
ference of 
land. 


§ 818 


Force at 
work on 


trade-wind 


zoues. 


348 THE PHYSICAL GEOGRAPHY OF THE SEA. 


are to the north, or on the polar side of the north-east 
trade-wind zone; whereas but a small part of Australia, 
less of South America, and still less of South Africa, 
are situated on the polar side of the zone of south-east 
rade-winds. In other words, there are on the polar 
side of the south-east trade-winds no great plains, except 
in Australia, upon which the rays of the sun, in the 
summer of the other hemisphere, can play with force 
enough to rarefy the air sufficiently to materially interrupt 
these winds in their course. But, besides the vast area 
of such plains in the northern hemisphere, on the polar 
side of its trade-wind belt, the heat of which is sufficient” 
to draw these trade-winds back, there are numerous other 
districts in the extra-tropical regions of our hemisphere, 
the summer heat of which, though it be not sufficient to 
turn the north-east trade-winds back, and make a mon- 
soon of them, yet may be sufficient to weaken them in 
their force, and, by retarding them, draw the south-east 
trade-winds over into the northern hemisphere. 

Now, as this interference from the land takes place in 
the summer only, we might infer, without appealing to 
actual observation, that the position of these trade-wind 
zones is variable; that is, that the equatorial edge of the 
south-east trade-wind zone is farther to the north in our 
summer, when the north-east trades are most feeble, than 
it is in winter, when they are strongest. 

We have here, then, at work upon these trade-wind 
zones, a force now weak, now strong, which, of course, 
would cause these zones to vibrate up and down the 
ocean, and within certain limits, according to the season 
of the year. These limits are given on Plate VIII. for 


1 ¢ 810. 2 § 815. 


THE WINDS. 349 


spring and autumn. During the latter season these zones 
reach their extreme northern declination, and in our 
spring their utmost limits toward the south. 

Changing of the Monsoons.—Lieutenant Jansen, in 
his appendix to the Dutch edition of this work, thus 
describes this phenomenon :— 

“ We have seen’that the calms which precede the sea- 
breeze generally continue longer, and are accompanied 
with an upward motion of the air; that, on the contrary, 
those which precede the land-breeze are, in the Java Sea, 
generally of shorter duration, accompanied by a heavy 
atmosphere; and that there is also an evident difference 
between the conversion of the land-breeze into the sea- 
breeze and of the latter into the former. 

“Even as the calms vary, so there appears to be a 
marked difference between the changing of the monsoons 
in the spring and in the autumn in the Java Sea, As 
soon as the sun has crossed the equator, and its vertical 
rays begin to play more and more perpendicularly upon 
the northern hemisphere, the inland plains of Asia, North 
Africa, and of North America, are so heated, as to give 
birth to the south-west monsoons in the China Sea, in the 
North Indian Ocean, in the North Atlantic, and upon the 
west coast of Central America: then the north-west mon- 
soon disappears from the East Indian Archipelago, and gives 
place to the south-east trade-wind, which is known as the 
east monsoon ; just as the north-west wind, which prevails 
during the southern summer, is called the west monsoon, 

“This is the only monsoon which is found in the 
southern hemisphere, while in the northern hemisphere the 
north-east trade-wind blows in the China Sea and in the 


1 § 262, 


CHAPTER 
xIY. 


§ 819 


Jansen on 
the chang: 
ing of 

monsoons. 


§ 820 


Monsoons 
in Java 
Sea. 


§ 821 
Monsoons 
in differ- 
ent hemi- 
spheres, 


350 THE PHYSICAL GEOGRAPHY OF THE SEA. 


exapter Tndian Ocean; in the East Indian Archipelago the west 

ou monsoon prevails ; and here, when the south-east trade 

blows as the east monsoon, we find the south-west mon- 

soon in the adjacent seas of the northern hemisphere. 

Generally the westerly monsoons blow during the summer 
months of the hemisphere wherein they are found. 

§ 822 “As the land-breeze daily destroys in miniature the 
ees regular flow of the trade-wind, so does the latter the west 
other. monsoon in larger measure; and observations will be able to 

decide whether monthly disturbances do not also take place. 

§ 823 “In the Java Sea, during the month of February, the 
Monsoons west monsoon blows strong almost continually ; in March 
Sea it blows intermittingly, and with hard squalls; but in 

April the squalls become less frequent and less severe. 
Now the changing commences. All at once gusts begin to 
spring up from the east: they are often followed by 
calms. The clouds which crowd themselves upon the 
clear sky give warning of the combat in the upper air 
which the currents there are about to wage with each other. 

§ 824 “The electricity, driven thereby out of its natural 
Electricity channels, in which, unobserved, it has been performing 

silently, but with the full consciousness of its power, the 
mysterious task appointed to it, now displays itself with 
dazzling majesty ; its sheen and its voice fill with as- 
tonishment and deep reverence the mind of the sailor— 
so susceptible, in the presence of storm and darkness, to 
impressions that inspire feelings both of dread and 
anxiety, which by pretended occupations he strives in 
vain to conceal.* 


* No phenomenon in nature makes a deeper impression upon the sailor than a 
dark thunder-storm in a calm at sea,—J ANSEN, 


THE WINDS. 351 


“Day and night we now have thunder-storms. The cuaprea 
XIV. 

§ 825 

Thunder- 


The combat which the clouds seem to court and to dread ‘°"™* 


clouds are in continual movement, and the darkened air, 


laden with vapour, flies in all directions through the skies. 


appears to make them more thirsty than ever. They re- 
sort to extraordinary means to refresh themselves: in 
tunnel form, when time and opportunity fail to allow 
them to quench their thirst from the surrounding atmos- 
phere in the usual manner, they descend near the surface 
of the sea, and appear to lap the water directly up with 
their black mouths. Water-spouts, thus created, are often alee 
seen in the changing season, especially among small 
groups of islands, which appear to give rise to them.* 
The water-spouts are not always accompanied by strong 
winds ; frequently more than one is seen at a time, where- 
upon the clouds whence they proceed disperse in various 
directions, and the ends of the water-spouts bending over 
finally causes them to break in the middle, although the 
water which is now seen foaming around their bases has 
suffered little or no movement laterally. 

“ Yet often the wind prevents the formation of water- § 826 

spouts. In their stead the wind-spout shoots up like an a 
arrow, and the sea seems to try in vain to keep it back. 
The sea, lashed into fury, marks with foam the path 
along which the conflict rages, and roars with the noise 
of its water-spouts; and woe to the rash mariner who 
ventures therein !+ 


* T neyer saw more water-spouts than in the Archipelago of Bioun Singen, 
during the changing. Almost daily we saw one or more.—J ANSEN. 

+ The air-spouts near the equator always appear to me to be more dangerous 
than the water-spouts. I have once had one of the latter to pass a ship’s length 
ahead of me, but I perceived little else than a water-fall in which I thought to 
come, yet no wind, Yet the water-spouts there also are not to be trusted. I 


CHAPTER 
XIV. 


Height of 
spouts. 


Duration. 


Bi THE PHYSICAL GEOGRAPHY OF THE SEA. 


“The height of the spouts is usually somewhat less 
than 200 yards, and their diameter not more than 20 
feet, yet they are often taller and thicker; when the 
opportunity of correctly measuring them has been favour- 
able, however, as it generally was when they passed be- 
tween the islands, so that the distance of their bases could 
be accurately determined, I have never found them 
higher than 700 ells, nor thicker than 50 ells. In Octo- 
ber, in the Archipelago of Bioun, they travel from south- 
west to north-east. They seldom last longer than five 
minutes; generally they are dissipated in less time. As 
they are going away, the bulbous tube, which is as pal- 
pable as that of a thermometer, becomes broader at the 
base, and little clouds, like steam from the pipe of a loco- 
motive, are continually thrown off from the circumference 
of the spout, and gradually the water is released, and the 
cloud whence the spout came again closes its mouth.* 


have seen such spouts go up out of the water upon the shore, where they over- 
threw strong isolated frame-houses. I have, however, never been in a situation 
to observe in what direction they revolved.—J ANSEN, 

* Miniature water-spouts may be produced artificially by means of electricity, 
and those in nature are supposed to be caused by the display of electrical pheno- 
mena. ‘‘ From the conductor of an electrical machine,” says Dr. Bonzano of 
New Orleans, ‘‘ suspend by a wire or chain a small metallic ball (one of wood 
covered with tinfoil), and under the ball place a rather wide metallic basin con- 
taining some oil of turpentine, at the distance of about three quarters of an inch. 
If the handle of the machine be now turned slowly, the liquid in the basin will 
begin to move in different directions, and form whirlpools. As the electricity on 
the conductor accumulates, the troubled liquid will elevate itself in the centre, 
and at last become attached to the ball. Draw off the electricity from the con- 
ductor to let the liquid resume its position: a portion of the turpentine remains 
attached to the ball. Turn the handle again very slowly, and observe now the 
few drops adhering to the ball assume a conical shape, with the apex downward, 
while the liquid under it assumes also a conical shape, the apex upward, until 
both meet. As the liquid does not accumulate on the ball, there must neces- 
sarily be as great a current downward as upward, giving the column of liquid a 
rapid circular motion, which continues until the electricity from the conductor 
ig nearly all discharged silently, or until it is discharged by a spark descending 


THE WINDS. 353 


“During the changing of the monsoons, it is mostly 
calm or cool, with gentle breezes, varied with rain-storms 
and light gales from all points of the compass. They are 
harassing to the crew, who, with burning faces under the 
clouded skies,* impatiently trim the sails to the changing 
winds. However, the atmosphere generally becomes clear, 
and, contrary to expectation, the north-west wind comes 
from a clear sky: about the coming of the monsoon it is 
northerly. Now the clouds are again packed together ; 
the wind dies away, but it will soon be waked up, to 
come again from another point. Finally, the regular 
land and sea breezes gradually replace rain and tempests, 
calms and gentle gales. The rain holds up during the 
day, and in the Java Sea we have the east monsoon. It 
is then May. Farther to the south than the Java Sea 
the east monsoon commences in April. + 

“This monsoon prevails in September and October, 
when it turns to become the west monsoon. It has 
seemed to me that the east monsoon does not blow the 
same in every month; that its direction becomes more 


into the liquid. The same phenomena take place with oil or water. Using the 
latter liquid, the ball must be brought much nearer, or a much greater quantity 
of electricity is necessary to raise it. 

“Tf, in this experiment, we let the ball swing to and fro, the little water-spout 
will travel over its miniature sea, carrying its whirlpools along with it. When 
it breaks up, a portion of the liquid, and with it anything it may contain, re- 
mains attached to the ball. The fish, seeds, leaves, &c., that have fallen to 
the earth in rain-squalls, may have owed their elevation to the clouds to the 
same cause that attaches a few drops of the liquid, with its particles of impuri- 
ties, to the ball.” 

* At sea the face and hands burn (change the skin) much quicker under a 
clouded than under a clear sky.—J ANSEN. 

+ In the north-east part of the Archipelago the east monsoon is the rainy mon- 
soon. ‘he phenomena in the north-east part are thus wholly different from those 
in the Java Sea.—J anseEn. 

1 § 851. 
23 


CHAPTER 
xIy. 


§ 827 
The wea- 
ther dur- 
ing the 
changes of 
monsoons 


§ 828 


East mon- 
soon. 


et 


Effects of 
monsoon 
in straits of 
the Archi- 
pelago. 


Moon pass- 
ing mevi- 


§ 830 


Change of 
monsoons 
on Java 
coast. 


354 THE PHYSICAL GEOGRAPHY OF THE SEA. 


southerly, and its power greater, after it has prevailed for 
some time.* 

“It is sufficiently important to fix the attention, seeing 
that these circumstances have great influence upon the 
winds in the many straits of the Archipelago, in which 
strong currents run most of the time. Especially in the 
straits to the east of Java, these currents are very strong. 
I have been unable to stem the current with eight-mile 
speed. However, they do not always flow equally strong, 
nor always in the same direction. They are probably the 
strongest when the tidal current and the equatorial cur- 
rent meet together. It is said that the currents in the 
straits during the east monsoon run eighteen hours to the 
north, and six hours to the south, and the reverse during 
the west monsoon. ‘The passing of the meridian by the 
moon appears to be the fixed point of time for the turn- 
ing of the currents. It is probable that the heated water 
of the Archipelago is discharged to the north during the 
east monsoon, and to the south during the west monsoon. 

“ As the sea makes the coming of the southern summer 
known to the inhabitants of the Java coast,+ the turning 
of the east monsoon into the west monsoon commences. 
After the sun has finished its yearly task in the northern 
hemisphere, and brings its powerful influence to operate 

* As is well known, the Strait of Soerabaya forms an elbow whose easterly 
outlet opens to the east, while the westerly outlet opens to the north. In the 
beginning of the east monsoon the sea-wind (east monsoon) blows through the 
westerly entrance as far as Grissee (in the elbow); in the latter part of this mon- 
soon, the sea-wind blows, on the contrary, through the easterly entrance as far 
as Sambilangan (the narrow passage where the westerly outlet opens into the 
sea).—J ANSEN, 

+ In the Archipelago we have generally high water but once a day, and, with 


the equinoxes, the tides also turn. The places which have high water by day in 
one monsoon get it at night in the other. —JanNsEN. 


THE WINDS. ODD 


in the southern hemisphere, a change is at once perceived 
in the constant fine weather of the east monsoon of the 
Java Sea. As soon as it is at its height upon the Java 
Sea (6° south), then the true turning of the monsoon 
begins, and is accomplished much more rapidly than the 
spring turning. The calms then are not so continuous. 
The combat in the upper atmosphere appears to be less 
violent; the south-east trade, which has blown as the 
east monsoon, does not seem to have sufficient strength 
to resist the aggressors, who, with wild storms from the 
north-west and west, make their superiority known. 
Upon and in the neighbourhood of the land, thunder- 
storms occur, but at sea they are less frequent. 

“The atmosphere, alternately clear and cloudy, moves 
more definitely over from the north-west, so that it 
appears as if no combat were there waged, and the south- 
east gives place without a contest. 

“The land-breezes become less frequent, and the phe- 
nomena by day and by night become, in a certain sense, 
more accordant with each other. Storms of wind and 
rain beneath a clouded sky alternate with severe gales 
and steady winds. In the last of November the west 
monsoon is permanent. 

“Such are the shiftings. But what have they to do 
with the general system of the circulation of the atmos- 
phere? Whenever we read attentively the beautiful 
meditations of the founder of the Meteorology of the 
Sea, and follow him in the development of his hypothesis, 
which lays open to view the wheels whereby the atmos- 
phere performs its varied and comprehensive task with 
order and regularity, then it will not be necessary to furnish 


CHAPTER 
xiv. 


_ 


§ 831 


Movement 
of atmo- 
sphere. 


§ 832 
Land- 
breezes 
less fre- 
quent. 


§ 835 
What the 
** shift- 
ings” have 
to do with 
general 
systein of 
circulation 


896 THE PHYSICAL GEOGRAPHY OF THE SEA. 


cuarter proof that these turnings are nothing else than the pass- 
ea ing of a belt of calms which separates the monsoons from 
each other, and which, as we know, goes annually with 
the sun from the south to the north, and back over the 

torrid zone to and fro. 
§ 834 “So also the calms, which precede the land and sea 
Theealms winds, are turned back. If, at the coming of the land- 


which pre- 


cede land wind in the hills, we go with it to the coast—to the sea, 
breezes, we shall perceive that it shoves away the calms which 
preceded it from the hills to the coast, and so far upon 
the sea as the land-wind extends. Here, upon the limits 
of the permanent monsoon, the place for the calms remains 
for the night, to be turned back to the land and to the 
hills the following day by the sea-wind. In every place 
where these calms go, the land and sea winds turn back. 
If various observers, placed between the hills and the sea, 
and between the coast and the farthest limit of the land- 
wind, noted the moment when they perceived the calms, 
and that when they perceived the land-wind, then by 
this means they would learn how broad the belt of calms 
has been, and with what rapidity they are pushed over 
the sea and over the land. And even though the results 
one day should be found not to agree very well with 
those of another, they would at least obtain an average 
The calms thereof which would be of value. So, on a larger scale, 
which 


separate the belt of calms which separates the monsoons from each 


monsoons 


from each Other presses in the spring from the south to the north, 
other. 


and in autumn from the north to the south, and changes 
the monsoons in every place where it presses.” * 


* Bijdrage Natuurkiindige Beschrijving der zeén, vertaald door M. H. Jansen, 
Luitenant ter zee. 


THE WINDS. 335) 7 


Tue Catm Betts.—There is between the two systems 
of trade-winds a region of calms, known as the equatorial 
calms. It has a mean average breadth of about six 
degrees of latitude. In this region, the air which is 
brought to the equator by the north-east and south-east 
trades ascends. This belt of calms always separates 
these two trade-wind zones, and travels up and down 
with them. If we liken this belt of equatorial calms to 
an immense atmospherical trough, extending, as it does, 
entirely around the earth; and if we liken the north-east 
and south-east trade-winds to two streams discharging 
themselves into it; we shall see that we have two currents 
perpetually running in at the bottom, and that, therefore, 
we must have as much air as the two currents bring in 
at the bottom to flow out at the top. What flows out 
at the top is carried back north and south by these upper 
currents, which are thus proved to exist, and to flow 
counter to the trade-winds. 

Using still further this mode of illustration: if we 
liken the calm belt of Cancer and the calm belt of Capri- 
corn each to a great atmospherical trough extending 
around the earth also, we shall see that in this case the 
currents are running in at the top and out at the 
bottom.’ 

The belt of equatorial calms is a belt of constant pre- 
cipitation, Captain Wilkes, of the Exploring Expedition, 
when he crossed it in 1838, found it to extend from 4° 
north to 12° north. He was ten days in crossing it, and 
during those ten days rain fell to the depth of 6.15 inches, 
or at the rate of eighteen feet and upwards during the 
year. In the summer months this belt of calms is found 


es 


1 § 132, 


CHAPTER 
XIV. 

§ 835 

Equatorial} 

calins. 


§ 836 


Calm belts 
of Cancer 
and Capri- 
corn. 


§ 837 


Equatorial 
calms a 

belt of pre- 
cipitation. 


358 THE PHYSICAL GEOGRAPHY OF THE SEA. 


Cnet between the parallels of 8° and 14° of north latitude, and 


in the spring between 5° south and 4° north.’ 
§ 838 This calm belt, in its motions from south to north and 


Regular 
motion of 
calm belt. 


back, carries with it the rainy seasons of the torrid zone, 
always arriving at certain parallels at stated periods of 
the year; consequently, by attentively considering Plate 
VIIL., one can tell what places within the range of this 
zone have, during the year, two rainy seasons, what one, 
and what are the rainy months for each locality. 


$839 Were the north-east and the south-east trades, with 
Appear- 
ance that 
trades and 
calms 


would pre- hy the motion of these belts or girdles alone, tell the 


sent to an 


the belt of equatorial calms, of different colours, and 
visible to an astronomer in one of the planets, he might, 


astrono- seasons with us. He would see them at one season 


mer in one 


ee going north, then appearing stationary, and then com- 
mencing their return to the south, But though he 
would observe’ that they follow the sun in his annual 
course, he would remark that they do not change their 
latitude as much as the sun does his declination; he 
would, therefore, discover that their extremes of declina- 
tion are not so far asunder as the tropics of Cancer and 
Capricorn, though in certain seasons the changes from 
day to day are very great. He would observe that these 
zones of winds and calms have their tropics or stationary 
nodes, about which they linger near three months at a 
time ; and that they pass from one of their tropics to the 
other in a little less than another three months, Thus he 
would observe the whole system of belts to go north from 
the latter part of May till some time in August; then 
they would stop and remain stationary till winter, in 
December, when again they would commence to move 


1 See Plate VIII. 2 $ 188. 


THE WINDS. 359 


“ 


rapidly over the ocean, and down toward the south, until 
the last of February or the first of March; then again 
they would become stationary, and remain about this, 
their southern tropic, till May again. 

THE Horse LATITUDES.—Having completed the physi- 
eal examination of the equatorial calms and winds, if the 
supposed observer should now turn his telescope toward 
the poles of our earth, he would observe a zone of calms 
bordering the north-east trade-winds on the north, and 
another bordering the south-east trade-winds on the south? 
These calm zones also would be observed to vibrate up 
and down with the trade-wind zones, partaking® of their 
motions, and following the declination of the sun. 

On the polar side of each of these two calm zones 
there would be a broad band extending up into the 
Polar Regions, the prevailing winds within which are the 
opposites of the trade-winds, namely, south-west in the 
northern and north-west in the southern hemisphere. The 
equatorial edge of these calm belts is near the tropics, 
and their average breadth is 10° or 12° On one side of 
these belts* the winds blow perpetually toward the equa- 
tor ; on the other, their prevailing direction is toward the 
poles. They are called’the “horse latitudes” by seamen. 

Along the polar borders of these two calm belts’ we 
have another region of precipitatior, though generally 
the rains here are not so constant as they are in the 
equatorial calms, The precipitation near the tropical 
calms is nevertheless sufficient to mark the seasons; for 
whenever these calm zones, as they go from north to 
south with the sun, leave a given parallel, the rainy 
season of that parallel, if it be in winter, is said to com- 


ie 131, 2 § 137, 2 $191, 
48131: 5 $131, ® § 190. 


CHAPTER 
D.B  fes 


§$ 840 


The horse 
latitudes, 


§ 841 


Polar calm 
belts. 


§ 842 


Polar re- 
gion of 
precipita 
tion. 


CHAPTER 
XIV. 


§ 843 
Westerly 
winds. 


§ 844 


South-west 
passage 
winds. 


§ 845 
Necessity 
for an 
upper cur- 
rent, 


§ 846 


360 THE PHYSICAL GEOGRAPHY OF THE SEA. 


mence. Hence we may explain the rainy season in Chili 
at the south, and in California at the north. 

Tur WESTERLY WINDS.—To complete the physical 
examination of the earth’s atmosphere which we have 
supposed an astronomer in one of the planets to have 
undertaken according to the facts developed by the Wind 
and Current Charts, it remains for him to turn his tele- 
scope upon the south-west passage winds of the northern 
hemisphere, pursue them into the Arctic Regions, and see 
theoretically how they get there, and, being there, what 
becomes of them. 

From the parallel of 40° up toward the north pole, 
the prevailing winds, as already remarked, are the south- 
west passage winds, or, as they are more generally called 
by inariners, the “ westerly” winds ; these, in the Atlantic, 
prevail over the “easterly” winds in the ratio of about 
two to one. 

Now if we suppose, and such is probably the case, these 
“westerly” winds to convey in two days a greater volume 
of atmosphere toward the arctic circle than those “easterly” 
winds can bring back in one, we establish the necessity 
for an upper current by which this difference may be 
returned to the tropical calms of our hemisphere. There- 
fore there must be some place in the Polar Regions’ at 
which these south-west winds cease to go north, and from 
which they commence their return to the south, and this 
locality must be in a region peculiarly Hable to calms. 
It is another atmospherical node in which the motion of 
the air is upward, with a decrease of barometric pressure. 
It is marked P, Plate I. 

To appreciate the force and volume of these polar-bound 


1 Plate VIII. 2 § 154. 


THE WINDS. 361 


winds in the svuthern hemisphere, it is necessary that cuarrTer 
XIV. 


one should “run them down” in that waste of waters 


beyond the parallel of 40° south, where “ the winds howl ae ro 
and the seas roar.” The billows there lift themselves up cane ee 


bound 


in long ridges with deep hollows between them. They winus 
run high and fast, tossing their white caps aloft in the 
air, looking like the green hills of a rolling prairie capped 
with snow, and chasing each other in sport. Still their 
march is stately and their roll majestic. The scenery 
among them is grand, and the Australian-bound trader, 
after doubling the Cape of Good Hope, finds herself 
followed for weeks at a time by these magnificent rolling 
swells, driven and lashed by the “brave west winds” 
furiously. A sailor’s bride, performing this voyage with 
her gallant husband, thus alludes in her “abstract log” to 
these rolling seas :— 

“We had some magnificent gales off the Cape, when § 847 
the colouring of the waves, the transition from gray to Abstract 


from the 
clear brilliant green, with the milky-white foam, struck 1s ofa 


me as most exquisite. And then in rough weather the bride, 
moral picture is so fine, the calmness and activity required 
is such an exhibition of the power of mind over the 
elements, that I admired the sailors fully as much as the 
sea,—and, of course, the sailor in command most of all ; 


indeed, a sea voyage more than fulfils my expectations.” 


CHAPTER 
XV. 


§ 848 


Thermal 
Charts. 


Tsothermal 
lines. 


362 THE PHYSICAL GEOGRAPHY OF THE SEA, 


CHAPTER XY. 


CLIMATES OF THE OCEAN. 


Milky Way of the Sea, § 848.—Contrasted with Climates Ashore, 852. —Move- 
ments of Isotherms, 854.—Mean Temperature of Sea and Air, 860.—Rain in 
high Latitudes at Sea, 863.—Climate of England affected by Coast Line of 
Brazil, 871.—The Gulf of Guinea, 875.—Summer in the Northern Hemisphere 
hotter than in the Southern, 883.—A Harbour for Icebergs, 884.—Course of 
the Isothermal] Line across the Atlantic, 8&7. 


THERMAL Charts, showing the temperature of the surface 
of the Atlantic Ocean by actual observations made indis- 
criminately all over it, and at all times of the year, have 
been published by the National Observatory. The iso- 
thermal lines which these charts enable us to draw, and 
some of which are traced on Plate IV., afford the navigator 
and the philosopher much valuable and interesting infor- 
mation touching the circulation of the oceanic waters, 
including the phenomena of the cold and warm sea 
currents; they also cast light upon the climatology of the 
sea, its hyetographic peculiarities, and the climatic condi- 
tions of various regions of the earth,—they show that the 
vrofile of the coast-line of intertropical America assists to 
give expression to the mild climate of Southern Europe ; 
they also increase our knowledge concerning the Gulf 
Stream, for it enables us to mark out, for the mariner’s 
guidance, that “ Milky Way” in the ocean, the waters of 
which teem, and sparkle, and glow with life and incipient 
organisms as they run across the Atlantic. In them are 
found the clusters and nebulz of the sea which stud and 
deck the great highway of ships on their voyage between 


CLIMATES OF THE OCEAN. 363 


the Old World and the New; and these lines assist to cmarrer 
point out for the navigator their limits and his way. ee 
They show this via lactea to have a vibratory motion 

in the sea that calls to mind the graceful wavings of a 
pennon as it floats gently to the breeze. Indeed, if we 
imagine the head of the Gulf Stream to be hemmed in 

by the land in the Straits of Bemini, and to be stationary 
there, and then liken the tail of the Stream itself to an 
immense pennon floating gently in the current, such a 
motion as such a streamer may be imagined to have— 
very much such a motion—do my researches show the 

tail of the Gulf Stream to have. Running between 
banks of cold water; it is pressed now from the north, 

now from the south, according as the great masses of sea 
water on either hand may change or fluctuate in tempera- 

ture. 

In September, when the waters in the cold regions of § 849 
the north have been tempered and made warm and light fefrence 
by the heat of summer, its limits on the left (Plate VI.) v: 
are as denoted by the line of arrows; but after this great 
sun-swing, the waters on the left side begin to lose their 
heat, grow cold, become heavy, and press the hot waters 
of this stream into the channel marked out for them. 

Thus it acts like a pendulum, slowly propelled by heat § 850 


on one side and repelled by cold on the other. In this onrono- 
graph for 


view, it becomes a chronograph for the sea, keeping time the sea 


for its inhabitants, and marking the seasons for the great 
whales ; and there it has been, for all time, vibrating to 
and fro, once every year, swinging from north to south, 
and from south to north again, a great self-regulating, 
self-compensating pendulum. 


ASN 


564 THE PHYSICAL GEOGRAPHY OF THE SEA. 


cuapteR In seeking information concerning the climates of the 

~~ ocean, it is well not to forget this remarkable contrast 
mee | between its climatology and that of the land—namely, on 
lvey ofthe the Jand, February and August are considered the coldest 


Ofean con- 


tasted, and the hottest months; but to the inhabitants of the 
ofland. sea the annual extremes of cold and heat occur in the 
months of March and September. On the dry land, after 

the ‘winter is past and gone,” the solid parts of the 

earth continue to receive from the sun more heat in the 

day than they radiate at night; consequently there is an 
accumulation of caloric, which continues to increase until 
August. The summer is now at its height; for, with 

the close of this month, the solid parts of the earth’s 

crust and the atmosphere above begin to dispense with 

their heat faster than the rays of the sun can impart fresh 
supplies, and, consequently, the climates which they regu- 

late grow cooler and cooler until the dead of winter again. 

$852 Butatsea a different rule seems to prevail. Its waters 
Seawater are the store-houses in which the surplus heat of summer 


a store- 


bens tne is stored away against the severity of winter, and its 
suumer, Waters continue to grow warmer for a month after the 
weather on shore has begun to get cool This brings the 
highest temperature to the sea in September, the lowest 
in March. Plate IV. is intended to show the extremes of 
heat and cold to which the waters, not the ice of the sea, 
are annually subjected; and therefore the isotherms of 
40°, 50°, 60°, 70°, and 80°, have been drawn for March 
and September, the months of extreme heat and extreme 
cold to the inhabitants of the “ great deep.” Corre- 
sponding isotherms for any other month will fall between 
these, taken by pairs. Thus the isotherm of 70° for 


CLIMATES OF THE OCEAN. 3865 


July will fall nearly midway between the same isotherms 
(70°) for March and September. 

A careful study of this plate, and the contemplation of 
the benign influences of the sea upon the climates which 
we enjoy, suggest many beautiful thoughts; for by such 
study we get a glimpse into the arrangements and the 
details of that exquisite machinery in the ocean which 
enables it to perform all its offices, and to answer with 
fidelity its marvellous adaptations. 

How, let us inquire, does the isotherm of 80°, for 
instance, get from its position in March to its position in 
September? Is it wafted along by currents; that is, by 
water which, after having been heated near the equator 
to 80°, then flows to the north with this temperature ? 
or is it carried there simply by the rays of the sun, as 
the snow-line is carried up the mountain in summer? 
We have reason to believe that it is carried from one 
parallel to another by each of these agents acting together, 
but mostly through the instrumentality of currents, for 
currents are the chief agents for distributing heat to the 
various parts of the ocean, The sun with his rays would, 
were it not for currents, raise the water in the torrid zone 
to blood heat; but before that can be done, they run off 
with it toward the poles, softening, and mitigating, and 
tempering climates by the way. The provision for this 
is as beautiful as it is benign: for, to answer a physical 
adaptation, it is provided by a law of nature that, when 
the temperature of water is raised, it shall expand ; as it 
expands it must become lighter; and just in proportion 
as its specific gravity is altered, just in that proportion 
is equilibrium in the sea destroyed, Arrived at this 


CHAPTER 
XY. 


§ 853 
Benign in- 
fluence of 
sea on 
cliinates, 


§ 854 


Alteration 
of position 
of iso- 
therms, 


Advan- 
tages of 
currenta. 


CHAPTER 
XV. 


Remarks 
on iso- 
therms. 


§ 855 


Tsotherm 
of 80° 


§ 856 


Isotherm 
of 60° 


366 THE PHYSICAL GEOGRAPHY OF THE SEA, 


condition, it is ordained that this hot water shall obey 
another law of nature, which requires it to run away and 
hasten to restore that equilibrium. Were these isothermal 
lines moved only by the rays of the sun, they would slide 
up and down the ocean like so many parallels of latitude; 
at least there would be no breaks in them, like that which 
we see in the isotherm of 80° for September. It appears, 
from this line, that there is a part of the ocean near the 
equator, and about midway the Atlantic, which, with its 
waters, never does attain the temperature of 80° in Sep- 
tember. Moreover, this isotherm of 80° will pass, in the 
North Atlantic, from its extreme southern to its extreme 
northern declination, nearly two thousand miles, in about 
three months. Thus it travels at the rate of about 
twenty-two miles a day. Surely, without the aid of 
currents, the rays of the sun could not drive it along 
that fast. 

Being now left to the gradual process of cooling, by 
evaporation, atmospherical contact, and radiation, it occu- 
pies the other eight or nine months of the year in slowly 
returning south to the parallel whence it commenced to 
flow northward. As it does not cool as rapidly as it 
was heated, the disturbance of equilibrium by alteration 
of specific gravity is not so sudden, nor the current which 
is required to restore it so rapid. Hence the slow rate 
of movement at which this line travels on its march 
south. 

Between the meridians of 25° and 30° west, the iso- 
therm of 60° in September ascends as high as the parallel 
of 56°; in October it reaches the parallel of 50° north ; 
in November it is found between the parallels of 45° 


CLIMATES OF THE OCEAN. 367 


and 47°; and by December it has nearly reached its ex- 
treme southern descent between these meridians, which it 
accomplishes in January, standing then near the parallel 
of 40° It is all the rest of the year in returning north- 
ward to the parallel whence it commenced its flow to the 
south in September. 

Now it will be observed that this is the season (from 
September to December) immediately succeeding that in 
which the heat of the sun has been playing with greatest 
activity upon the polar ice. Its melted waters, which 
are thus put in motion in June, July, and August, would 
probably occupy the autumn months in reaching the pa- 
rallels indicated. These waters, though cold, and rising 
cradually in temperature as they flow south, are probably 
fresher, and, if so, probably lighter, than the sea water ; 
and therefore it may well be that both the warmer and 
cooler systems of these isothermal lines are made to vibrate 
up and down the ocean principally by a gentle surface 
current in the season of quick motion, and in the season 
of the slow motion principally by a gradual process of 
calorific absorption on the one hand, and by a gradual 
process of cooling on the other. 

We have precisely such phenomena exhibited by the 
waters of the Chesapeake Bay as they spread themselves 
over the sea in winter. At this season of the year, the 
charts show that water of very low temperature is found 
projecting out and overlapping the usual limits of the 
Gulf Stream. The outer edge of this cold water, though 
jagged, is circular in its shape, having its centre near the 
mouth of the bay. The waters of the bay, being fresher 
than those of the sea, may, therefore, though colder, be 


CHAPTER 
xv. 


§ 857 


Motions of 
isothermal 
lines. 


§ 858 


Waters of 
Chesa- 
peake Bay 


CHAFTER 
xv. 


$ 859 
Effect of 
changes in 
depth of 
water and 
shape of 
bottom. 


§ 860 


Inference 
in regard 
to mean 
tempera- 
ture of 
atmo- 
sphere. 


§ 861 


Causes 
which in- 
fluence the 
isotherm 
of 60°. 


9 


368 THE PHYSICAL GEOGRAPHY OF THE SEA, 


lighter than the warmer waters of the ocean. And thus 
we have repeated here, though on a smaller scale, the 
phenomenon as to the flow of cold waters from the north, 
which force the surface isotherm of 60° from latitude 56° 
to 40° during three or four months. 

Changes in the colour or depth of the water, and the 
shape of the bottom, &c., would also cause changes in the 
temperature of certain parts of the ocean, by increasing 
or diminishing the capacities of such parts to absorb or 
radiate heat; and this, to some extent, would cause a 
bending, or produce irregular curves in the isothermal 
lines. 

After a careful study of this plate, and the Thermal 
Charts of the Atlantic Ocean, from which the materials 
for the former were derived, I am led to infer that the 
mean temperature of the atmosphere between the paral- 
lels of 56° and 40° north, for instance, and over that part 
of the ocean in which we have been considering the 
fluctuations of the isothermal line of 60°, is at least 60° 
of Fahrenheit, and upward, from January to August, and 
that the heat which the waters of the ocean derive from 
this souree—atmospherical contact and radiation—is one 
of the causes which move the isotherm of 60° from its 
January to its September parallel. 

It is well to consider another of the causes which are 
at work upon the currents in this part of the ocean, and 
which tend to give the rapid southwardly motion to the 
isotherm of 60°. We know the mean dew-point must 
always be below the mean temperature of any given 
place, and that, consequently, as a general rule, at sea the 
mean dew-point due the isotherm of 60° is higher than 


CLIMATES OF THE OCEAN, 369 


the mean dew-point along the isotherm of 50°, and this, 
again, higher than that of 40°, this than 30°, and so on. 
Now suppose, merely for the sake of illustration, that the 
mean dew-point for each isotherm be 5° lower than the 
mean temperature, we should then have the atmosphere 
which crosses the isotherm of 60°, with a mean dew- 
point of 55°, gradually precipitating its vapours until it 
reaches the isotherm of 50°, with a mean dew-point of 
45°; by which difference of dew-point the total amount 
of precipitation over the entire zone between the isotherms 
of 60° and 50° has exceeded the total amount of evapo- 
ration from the same surface. The prevailing direction 
of the winds to the north of the fortieth parallel of north 
latitude is from the southward and westward ;’ in other 
words, it is from the higher to the lower isotherms. 
Passing, therefore, from a higher to a lower temperature 
over the ocean, the total amount of vapour deposited by 
any given volume of atmosphere, as it is blown from the 
vicinity of the tropical toward that of the polar regions, 
is greater than that which is taken up again. 

The area comprehended on Plate VIII. between the iso- 
therms of 40° and 50° Fahrenheit is less than the area com- 
vrehended between the isotherms 50° and 60°; and this, 
again, less than the area between this last and 70°; for the 
same reason that the area between the parallels of latitude 
50° and 60° is less than the area between the parallels of 
latitude 40° and 50°; therefore, more rain to the square 
inch ought to fall upon the ocean between the colder 
isotherms of 10° difference than between the warmer 
isotherms of the same difference. This is an interesting 
and an important view, therefore let me make myself 


————= en 
—_———- — 


1 Plate VIII. 
24 


CHAPTER 
Ve 


Prevailing 
direction 
of the 
winds 
north of 
fortieth 
parallel of 
north lati 
tude. 


$ 862 


Area be- 
tween iso- 
therms of 
40° and 
50°. 


CHAPTER 
XV. 


Remarks 
on rain in 
connection 
with iso- 
therms. 


§ 863 
Rain in 
high lati- 
tudes, 


§ 864 


370 THE PHYSICAL GEOGRAPHY OF THE SEA. 


clear: The aqueous isotherm of 50°, in its extreme 
northern reach, touches the parallel of 60° north. Now, 
between this and the equator there are but three iso- 
therms,—60°, 70°, and 80°,—with the common difference 
of 10°; but between the isotherm of 40° and the pole 
there are at least five others,—namely, 40°, 30°, 20°, 10°, 
0°—with a common difference of 10°. Thus, to the 
north of the isotherm 50°, the vapour which would satu- 
rate the atmosphere from zero, and perhaps far below, to 
near 40°, is deposited; while to the south of 50°, the 
vapour which would saturate it from the temperature of 
50° up to that of 80° can only be deposited : at least, 
such would be the case if there were no irregularities 
of heated plains, mountain ranges, land, &c., to disturb 
the laws of atmospherical circulation as they apply to the 
ocean, 

Having, therefore, theoretically, at sea more rain in 
high latitudes, we should have more clouds ; and therefore 
it would require a longer time for the sun, with his feeble 
rays, to raise the temperature of the cold water, which, 
from September to January, has brought the isotherm of 
60° from latitude 56° to 40°, than it did for these cool 
surface-currents to float it down. After this southward 
motion of the isotherm of 60° has been checked in Decem- 
ber by the cold, and after the sources of the current which 
brought it down have been bound in fetters of ice, it 
pauses in the long nights of the northern winter, and 
scarcely commences its return till the sun recrosses the 
equator, and increases its power as well in intensity as in 
duration. 

Thus, in studying the physical geography of the sea, 


CLIMATES OF THE OCEAN. oul 


we have the effects of night and day, of clouds and sun- cuaprer 
shine, upon its currents and its climates, beautifully de- pa 
veloped. These effects are modified by the operations of 
certain powerful agents which reside upon the land; 
nevertheless, feeble though those of the former class may 
be, they surely exist. 

Now, returning toward the south: we may, on the § 865 
other hand, infer that the mean atmospherical tempera- ference 


in regard 
ture for the parallels between which the isotherm of 80° to mean 


atmo- 


fluctuates is below 80°, at least for the nine months of its shel 
slow motion. This vibratory motion suggests the idea ture. 
that there is, probably somewhere between the isotherm 
of 80° in August and the isotherm of 60° in J anuary, a 
line or belt of invariable or nearly invariable tempera- 
ture, which extends on the surface of the ocean from one 
side of the Atlantic to the other. This line or band may 
have its cycles also, but they are probably of long and 
uncertain periods. 

The fact has been pretty clearly established, by the dis- § 866 
coveries to which the Wind and Current Charts have led, Weste 


halt of 


that the western half of the Atlantic Ocean is heated up, Sees 


not by the Gulf Stream alone, as is generally supposed, ein 
but by the great equatorial caldron to the west of longi- calaron. 
tude 35°, and to the north of Cape St. Roque, in Brazil. 

The lowest reach of the 80° isotherm for September,—if 

we except the remarkable equatorial flexure (Plate IV.) 
which actually extends from 40° north to the line,—to 

the west of the meridian of Cape St. Roque, is above its 
highest reach to the east of that meridian. And now 

that we have the fact, how obvious, beautiful, and striking 

is the cause! 


372 THE PHYSICAL GEOGRAPHY OF THE SEA, 


~O 


cuarTER Cape St. Roque is in 5° 30° south. Now, study the 
configuration of the Southern American Continent, from 

south this cape to the Windward Islands of the West Indies, 

pacers and take into account also certain physical conditions of 
these regions: The Amazon, always at a high tempera- 
ture, because it runs from west to east, is pouring an 
immense volume of warm water into this part of the 
ocean, As this water and the heat of the sun raise the 
temperature of the ocean along the equatorial sea-front 
of this coast, there is no escape for the liquid element, as 
it grows warmer and lighter, except to the north. The 
land on the south prevents the tepid waters from spread- 
ing out in that direction as they do to the east of 35° 
west, for here there is a space, about 18° of longitude 
broad, in which the sea is clear both to the north and 
south, 

§ 868 They must consequently flow north. A mere inspec- 
warm tion of the plate is sufficient to make obvious the fact 
east ofthe that the warm waters which are found east of the usual 
Sueam limits assigned the Gulf Stream, and between the paral- 

lels of 30° and 40° north, do not come from the Gulf 
Stream, but from this great equatorial caldron, which 
Cape St. Roque blocks up on the south, and which forces 
its overheated waters up to the fortieth degree of north 
latitude, not through the Caribbean Sea and Gulf Stream, 
but over the broad surface of the left bosom of the 
Atlantic Ocean. 

§869 Here we are again tempted to pause and admire the 
Redections heautiful revelations which, in the benign system of 

terrestrial adaptation, these researches into the physics 
of the sea unfold and spread out before us for contem- 


CLIMATES OF THE OCEAN. vie 


plation. In doing this, we shall have a free pardon from 
those at least who delight “to look through nature up to 
nature’s God.” 

What two things in nature can be apparently more 
remote in their physical relations to each other than the 
climate of Western Europe and the profile of a coast-line 
in South America? Yet this plate reveals to us not only 
the fact that these relations between the two are the 
most intimate, but makes us acquainted with the arrange- 
ments by which such relations are established. 

The barrier which the South American shore-line op- 
poses to the escape, on the south, of the hot waters from 
this great equatorial caldron of St. Roque, causes them 
to flow north, and in September, as the winter approaches, 
to heat up the western half of the Atlantic Ocean, and to 
cover it with a mantle of warmth above summer heat as 
far up as the parallel of 40°. Here heat to temper the 
winter climate of Western Europe is stored away as in 
an air-chamber to furnace-heated apartments ; and during 
the winter, when the fire of the solar rays sinks down, 
the westwardly winds and eastwardly currents are sent 
to perform their office in this benign arrangement. 
Though unstable and capricious to us they seem to be, 
they nevertheless “ fulfil His commandments” with regu- 
larity, and perform their offices with certainty. In 
tempering the climates of Europe with heat in winter 
that has been bottled away in the waters of the ocean 
during summer, these winds and currents are to be 
regarded as the flues and regulators for distributing it 
at the right time, and at the right places, in the right 
quantities, 


CHAPTER 
XV. 


—- 


§ 870 
Effect of 
South 
American 
coast line 
on West- 
erm Eu- 
rope 


§ 871 


Great cal- 
dron of 
St. Roque. 


Winds and 
currents 
regulators 
ot heat. 


CHAPTER 
xv 
§ 872 
Cooling 
down of 
the fur- 
nace. 


§ 873 


Isotherm 
f 80°. 


§ 874 
Another 
process of 
raising the 
tempera- 
ture of 
Europe. 


374 THE PHYSICAL GEOGRAPHY OF THE SEA. 


By March, when “the winter is past and gone,” the 
furnace which had been started by the rays of the sun 
in the previous summer, and which, by autumn, had 
heated up the ocean in our hemisphere, has cooled down. 
The caldron of St. Roque, ceasing in activity, has failed 
in its supplies, and the chambers of warmth upon the 
Northern Sea, having been exhausted of their heated water, 
which has been expended in the manner already explained, 
have contracted their limits. The surface of heated water 
which, in September, was spread out over the western half 
of the Atlantic, from the equator to the parallel of 40° 
north, and which raised this immense area to the tem- 
perature of 80° and upward, is not to be found in early 
spring on this side of the parallel of 8° north. 

The isotherm of 80° in March, after quitting the Ca- 
ribbean Sea, runs parallel with the South American coast 
toward Cape St. Roque, keeping some eight or ten de- 
erees from it. Therefore the heat dispensed over Europe 
from this caldron falls off in March. But at this season 
the sun comes forth with fresh supplies; he then crosses 
the line, and passes over into the northern hemisphere ; 
observations show that the process of heating the water 
in this great caldron for the next winter is now about 
to commence. 

In the meantime, so benign is the system of cosmical 
arrangements, another process of raising the temperature 
of Europe commences. The land is more readily im- 
pressed than the sea by the heat of the solar rays; at 
this season, then, the summer climate due these trans- 
atlantic latitudes is modified by the action of the sun’s 
rays directly upon the land. The land receives heat 


CLIMATES OF THE OCEAN. 375 


from them, but, instead of having the capacity of water 
for retaining it, it imparts it straightway to the air; and 
thus the proper climate, because it is the climate which 
the Creator has, for his own wise purposes, allotted to 
this portion of the earth, is maintained until the marine 
ealdron of Cape St. Roque and the tropics is again 
heated and brought into the state for supplying the 
means of maintaining the needful temperature in Europe 
auring the absence of the sun in the other hemisphere. 

In like manner, the Gulf of Guinea forms a caldron 
and a furnace, and spreads out over the South Atlantic 
an air-chamber for heating up in winter and keeping 
warm the extra-tropical regions of South America. Every 
traveller has remarked upon the mild climate of Patagonia 
and the Falkland Islands. 

“Temperature in high southern latitudes,” says a very 
close observer, who is co-operating with me in collecting 
materials, “differs greatly from the temperature in north- 
ern. In southern latitudes there seem to be no extremes 
of heat and cold, as at the north. Newport, Rhode 
Island, for instance, latitude 41° north, longitude 71° 
west, and Rio Negro, latitude 41° south, and longitude 
€3° west, as a comparison: in the former, cattle have to 
be stabled and fed during the winter, not being able to 
get a living in the fields on account of snow and ice. 
In the latter, the cattle feed in the fields all winter, there 
being plenty of vegetation and no use of hay. On the 
Falkland Islands (latitude 51-2° south), thousands of 
bullocks, sheep, and horses, are running wild over the 
country, gathering a living all through the winter.” 


CHAPTER 
xv. 


— 


§ 875 
Gulf of 
Guinea. 


§ 876 
Difference 
of tem- 
perature 
in high 
southern 
and north 
ern Jati- 
tudes. 


The water in the equatorial caldron of Guinea cannot § 877 


376 THE PHYSICAL GEOGRAPHY OF THE SEA. 


CHAPTER escape north—the shore-line will not permit it. It must, 
— therefore, overflow to the south, as that of St. Roque does 
to the north, carrying to Patagonia and the Falkland 
Islands, beyond 50° south, the winter climate of Charles- 
ton, South Carolina, on our side of the North Atlantic, 

or of the “ Emerald Island” on the other. 
$878 All geographers have noticed, and philosophers have 


Shore line 


of equator. frequently remarked upon the conformity, as to the shore- 


fal Ame- : : : . . 
rieaara line profile, of equatorial America and equatorial Africa. 


nS 879 It is true, we cannot now tell the reason, though 

explanations founded upon mere conjecture have been 

offered, why there should be this sort of jutting in and 

jutting out of the shore-line, as at Cape St. Roque and 

the Gulf of Guinea, on opposite sides of the Atlantic ; 

but one of the purposes, at least, which this peculiar con- 

figuration was intended to subserve, is without doubt now 
revealed to us. 

§880 We see that, by this configuration, two cisterns of hot 

Two cis- water are formed in this ocean; one of which distributes 


ternsof hot 


waterin heat and warmth to Western Europe; the other, at the 


ps. opposite season, tempers the climate of eastern Patagonia. 

§881  Phlegmatic must be the mind that is not impressed 
Bee with ideas of grandeur and simplicity as it contemplates 
eae that exquisite design, those benign and beautiful arrange- 
design by ments, by which the climate of one hemisphere is made 
teas to depend upon the curve of that line against which the 
fe. sea is made to dash its waves in the other. Impressed 


with the perfection of terrestrial adaptations, he who 
studies the economy of the great cosmical arrangements 
is reminded that not only is there design in giving shore- 
lines their profile, the land and the water their propor- 


CLIMATES OF THE OCEAN. ott 


tions, and in placing the desert and the pool where they cuaprer 
are, but the conviction is forced upon him also, that every sa 
hill and valley, with the grass upon its sides, have each 
its offices to perform in the grand design. 

March is, in the southern hemisphere, the first month § 882 
of autumn, as September is with us; consequently, we Fist 


month of 
should expect to find in the South Atlantic as large an autumn in 


area of water of 80° and upward in March, as we should hee 
find in the North Atlantic for September. But do we ? 
By no means. The area on this side of the equator is 
nearly double that on the other. 

Thus we have the sea as a witness to the fact that the § 883 
winds' had proclaimed, namely, that summer in the north- Semmes 


northern 


ern hemisphere is hotter than summer in the southern, be 


sphere is 


for the rays of the sun raise on this side of the equator hotter 
double the quantity of sea-surface to a given temperature te > 
that they do on the other side; at least this is the case 

in the Atlantic. Perhaps the breadth of the Pacific 
Ocean, the absence of large islands in the temperate 
regions north, the presence of New Holland, with Poly- 

nesia, in the South Pacific, may make a difference there ; 

but of this I cannot now speak, for thermal charts of 

that ocean have not yet been prepared. 

Pursuing the study of the climates of the sea, let us § 884 
now turn to Plate VI. Here we see how the cold waters, Rettrence 
as they come down from the Arctic Ocean through Davis’ V4 
Straits, press upon the warm waters of the Gulf Stream, 
and curve their channel somewhat into the form of a 
norse-shoe. Navigators have often been struck with the 
great and sudden changes in the temperature of the water 


hereabouts. In the course of a single day’s sail in this 


1 § 327. 


CHAPTER 
XV. 


—— 


Great re- 
ceptacle of 
icebergs. 


- The seat of 
the agent 
that causes 
the New- 
foundland 
fogs. 


§ 885 


Ofclimates 
in the 
ocean, 


378 THE PHYSICAL GEOGRAPHY OF THE SEA. 


part of the ocean, changes of 15°, or 20°, and even of 30°, 
have been observed to take place in the temperature of 
the sea. The cause has puzzled navigators long; but 
how obvious is it now made to appear! This “bend ” 
is the great receptacle of the icebergs which drift down 
from the north; covering frequently an area of hundreds 
of miles in extent, its waters differ as much as 20° 25°, 
and, in rare cases, even as much as 30° of temperature 
from those about it. Its shape and place are variable. 
Sometimes it is like a peninsula, or toncue of cold water, 
projected far down into the waters of the Gulf Stream. 
Sometimes the meridian upon which it is inserted into 
these is to the east of 40°, sometimes to the west of 50°, 
longitude. By its discovery we have clearly unmasked 
the very seat of that agent which produces the New- 
foundland fogs. It is spread out over an area frequently 
embracing several thousand square miles in extent, covered 
with cold water, and surrounded on three sides, at least, 
with an immense body of warm. May it not be that 
the proximity to each other of these two very unequally 
heated surfaces out upon the ocean would be attended by 
atmospherical phenomena not unlike those of the land 
and sea breezes? These warm currents of the sea are 
powerful meteorological agents. I have been enabled to 
trace, in thunder and lightning, the influence of the Gulf 
Stream in the eastern half of the Atlantic, as far north 
as the parallel of 55° north; for there, in the dead of 
winter, a thunder-storm is not unusual. 

These isothermal lines of 50°, 60°, 70°, 80°, &., may 
illustrate for us the manner in which the climates in 
the ocean are regulated. Like the sun in the ecliptic, 


CLIMATES OF THE OCEAN. 379 


they travel up and down the sea in declination, and serve cuarrer 
the monsters of the deep for signs and for seasons. ae 

It should be borne in mind that the lines of separation, § 886 

as drawn on Plate IX., between the cool and warm waters, zene 
or, more properly speaking, between the channels repre- 1% 
senting the great polar and equatorial flux and reflux, are 
not so sharp in nature as this plate would represent them. 
In the first place, the plate represents the mean or aver- 
age limits of these constant flows—polar and equatorial; 
whereas, with almost every wind that blows, and at every 
change of season, the line of meeting between their waters 
is shifted. In the next place, this line of meeting is 
drawn with a free hand on the plate, as if to represent 
an average; whereas there is reason to believe that this 
line in nature is variable and unstable as to position, and 
as to shape rough and jagged, and oftentimes deeply 
articulated. In the sea, the line of meeting between 
waters of different temperatures and density is not un- 
like the sutures of the skull-bone on a grand scale— 
very rough and jagged; but on the plate it is a line 
drawn with a free hand, for the purpose of showing the 
general direction and position of the channels in the sea 
through which its great polar and equatorial circulation 
is carried on. 

Now, continuing for a moment our examination of § 887 
Plate IV., we are struck with the fact that most of the ete 
thermal lines there drawn run from the western side of !V. 
the Atlantic toward the eastern, in a north-eastwardly 
direction; and that, as they approach the shores of this 
ocean on the east, they again turn down for lower lati- 
tudes and warmer climates. This feature in them indi- 
cates, more surely than any direct observations upon the 


380 THE PHYSICAL GEOGRAPHY OF THE SEA. 


carter currents can do, the presence, along the African shores 
=“. in the North Atlantic, of a large volume of cooler waters. 
Course of These are the waters which, having been first heated up 
fom st, in the caldron of St. Roque,! in the Caribbean Sea and 
fie “ Gulf of Mexico, have been made to run to the north, 
charged with heat and electricity to temper and regulate 
climates there. Having performed their offices, they 

have cooled down; but, obedient still to the “ Mighty 
Voice” which the winds and the waves obey, they now 
return by this channel along the African shore to be 

again replenished with warmth, and to keep up the 
system of beneficent and wholesome circulation designed 


tor the ocean. 


1 § 366. 


THE DRIFT OF THE SEA. 381 


CHAPTER XVI. 


THE DRIFT OF THE SEA. 


Data used for Plate IX., § 893.—The Antarctic Flow, 896.—A large Flow from 
the Indian Ocean, 902.—Patches of Coloured Water, 905. —The Lagullas Cur- 
rent, 909.—An immense Current, 911.—Tide Rips, 914.—Pulse of the Sea, 
920.—Diurnal Change of Sea Temperature, 922.—The Fisheries, 925.—The 
Sperm Whale, 926. 


THERE is a movement of the waters of the ocean which, cyaprus 
though it be a translation, yet does not amount to what ay 
is known to the mariner as current; for our nautical § 857 
instruments and the art of navigation have not been ean 
brought to that state of perfection which will enable 
navigators generally to detect as currents the flow to 

which I allude as drift. 

If we imagine an object to be set adrift in the ocean § 888 
at the equator, and if we suppose that it be of such a Suprosed 
nature that it would obey only the influence of sea water, ead set 
and not of the winds, this object, I imagine, would, in 
the course of time, find its way to the icy barriers about 
the poles, and again back among the tepid waters of the 
tropics. Such an object would illustrate the drift of the 
sea, and by its course would indicate the route which the 
surface-waters of the sea follow in their general channels 
of circulation to and fro between the equator and the 
poles. 

The object of Plate IX., therefore, is to illustrate, as § 889 
far as the present state of my researches enables me to Belen 
do, the circulation of the ocean, as influenced by heat and 


cold, and to indicate the routes by which the overheated 


382 THE PHYSICAL GEOGRAPHY OF THE SEA 


cnarter waters of the torrid zone escape to cooler regions on one 


XVI. 


— 


§ 890 


Gulf 
Stream. 


§ 891 


Extract 
from the 
log of the 
Herculean 


hand, and, on the other, the great channel-ways through 
which the same waters, after having been deprived of 
this heat in the extra-tropical or polar regions, return 
again toward the equator; it being assumed that the 
drift or flow is from the poles when the temperature of 
the surface water is below, and from the equatorial regions 
when it is above that due the latitude. Therefore, in a 
mere diagram, as this plate is, the numerous eddies and 
local currents which are found at sea are disregarded. 

Of all the currents in the sea, the Gulf Stream is the 
best defined; its limits, especially those of the left bank, 
are always well marked, and, as a rule, those of the right 
bank, as high as the parallel of the thirty-fifth degree of 
latitude, are quite distinct, being often visible to the eye. 
The Gulf Stream shifts its channel,’ but nevertheless its 
banks are often very distinct. As I write these remarks, 
the abstract log of the ship Herculean (William M. Cham- 
berlain), from Callao to Hampton Roads, in May 1854, is 
received, On the 11th of that month, being in latitude 
33° 39’ north, longitude 74° 56’ west (about one hun- 
dred and thirty miles east of Cape Fear), he remarks :— 

“ Moderate breezes, smooth sea, and fine weather. At 
ten o'clock fifty minutes, entered into the southern (right) 
edge of the stream, and in eight minutes the water rose 
six degrees. The edge of the stream was visible, as far 
as the eye could see, by the great rippling and large 
quantities of Gulf weed—more ‘ weed’ than I ever saw 
before, and J have been many times along this route in 
the last twenty years.” 


1§ 4. 


THE DRIFT OF THE SEA. 383 


In this diagram, therefore, I have thought it useless to cmaprme 
attempt a delineation of any of those currents, as the ae 
Rennell Current of the North Atlantic, the “ Connecting § o2 
Current” of the South, “ Mentor’s Counter Drift,” “ Ros- 
sel’s Drift of the South Pacific,” ete., which run now this 
way, now that, and which are frequently not felt by 
navigators at all. 

In overhauling the log-books for data for this chart, I § 893 
have followed vessels with the water thermometer to and Mode of 


ascertains 


fro across the seas, and taken the registrations of it ee 
exclusively for my guide, without regard to the reported rents 
set of the currents. When, in any latitude, the tempera- 
ture of the water has appeared too high or too low for 
that latitude, the inference has been that such water was 
warmed or cooled, as the case may be, in other latitudes, 
and that it has been conveyed to the place where found 
through the great channels of circulation in the ocean. 

If too warm, it is supposed’ that it had its temperature 
raised in warmer latitudes, and therefore the channel in 
which it is found leads from the equatorial regions. 

On the other hand, if the water be too cool for the § 894 
latitude, then the inference is that it has lost its heat in 
colder climates, and therefore is found in channels which 
lead from the polar regions, 

The arrow heads point to the direction in which the § 895 
waters are supposed to flow. Their rate, according to potest 
the best information that I have obtained, is, at a mean, 
only about four knots a day—rather less than more. 

Accordingly, therefore, as the immense volume of water § 896 
in the Antarctic regions is cooled down, it commences to 


1 § 889, 


384 THE PHYSICAL GEOGRAPHY OF THE SEA. 


cuarteR flow north. As indicated by the arrow heads, it strikes 
om, against Cape Horn, and is divided by the continent, one 
offiow portion going along the west coast as Humboldt’s Cur- 
avticre, rent;' the other, entering the South Atlantic, flows up 
ens into the Gulf of Guinea, on the coast of Africa. Now, 
as the waters of this polar flow approach the torrid zone, 
they grow warmer and warmer, and finally themselves 
become tropical in their temperature. They do not then, 
it may be supposed, stop their flow; on the contrary, they 
keep moving, for the very cause which brought them 
from the extra-tropical regions now operates to send them 
Effects of back. This cause is to be found in the difference of the 
Bante specific gravity at the two places. If, for instance, these 
waters, when they commence their flow from the hyper- 
borean regions, were at 50°, their specific gravity will 
correspond to that of sea water at 30°. But when they 
arrive in the Gulf of Guinea, or the Bay of Panama, 
having risen by the way to 80°, or perhaps 85°, their 
specific gravity becomes such as is due sea water of this 
temperature; and, since fluids differing in specific gra- 
vity can no more balance each other on the same level 
than can unequal weights in opposite scales, this hot 
water must now return to restore that equilibrium which 
it has destroyed in the sea by rising from 30° to 80° or 


85°. 
§897 Hence it will be perceived that those masses of water 
oa which are marked as cold are not always cold. They 


waters not 
always  oradually pass into warm; for in travelling from the poles 


old. 
; to the equator they partake of the temperature of the 
latitudes through which they flow, and grow warm. 


1 § 455, 


THE DRIFT OF THE SEA. 385 


Plate IX., therefore, is only introduced to give general 
ideas; nevertheless it is very instructive. See how the 
influx of cold water into the South Atlantic appears to 
divide the warm water, and squeeze it out at the sides, 
along the coasts of South Africa and Brazil. So, too, in 
the North Indian Ocean, the cold water again compelling 
the warm to escape along the land at the sides, as well 
as occasionally in the middle. 

In the North Atlantic and North Pacific, on the con- 
trary, the warm water appears to divide the cold, and to 
squeeze it out along the land at the sides. The impres- 
sion made by the cold current from Baffin’s Bay upon the 
Gulf Stream is strikingly beautiful. 

Why is it that these polar and equatorial waters should 
appear now to divide, and now to be divided? The Gulf 
Stream has revealed to us a fact in which the answer is 
involved. We learn from that stream that cold and 
warm sea waters are, in a measure, like oil and vine- 
‘gar; that is, there is among the particles of sea water 
at a high temperature, and among the particles of sea 
water at a low temperature, a peculiar molecular arrange- 
ment that is antagonistic to the free mixing up of cold 
and hot together. At any rate, that salt waters of dif- 
ferent temperatures do not readily intermingle at sea is 
obvious. 

Does not this same repugnance exist, at least in degree, 
between these bodies of cold and warm water of the plate? 
And if so, does not the phenomenon we are considering re- 
solve itself into a question of masses? The volume of warm 
water in the North Atlantic is greater than the volume 


1 § 28, 
25 


CHAPTER 
XVI. 


§ 898 


Influences 
of the cold 
flow. 


§ 899 


Of the 
warm flow 


$ 900 


Informa- 
tion 
gathered 
from the 
Gulf 
Stream. 


§ 901 


CHAPTER 
XVI. 


Counter- 
effects of 
hot and 
cold vol- 
umes of 
water 


§ 902 
Reflection 
of shore- 
line in the 
tempera- 
ture of the 
water. 


Toebergs. 


§ 903 


386 THE PHYSICAL GEOGRAPHY OF THE SEA. 


of cold water that meets and opposes it; consequently, 
the warm thrusts the cold aside, dividing and compel- 
ling it to go round. The same thing is repeated in 
the North Pacific, whereas the converse obtains in the 
South Atlantic. Here the great polar flow, after having 
been divided by the American continent, enters the At- 
lantic, and filling up nearly the whole of the immense 
space between South America and Africa, seems to press 
the warm waters of the tropics aside, compelling them to 
drift along the coast on either hand. 

Another feature of the sea is a sort of reflection or 
recast of the shore-line in the temperature of the water. 
This feature is most striking in the North Pacific and 
Indian Oceans. The remarkable intrusion of the cool 
into the volume of warm waters to the southward of 
the Aleutian Islands, is not unlike that which the cool 
waters from Davis’ Straits make in the Atlantic upon 
the Gulf Stream. In sailing through this “ horse-shoe,” 
or bend in the Gulf Stream, Captain N. B. Grant, of 
the American ship Lady Arbella, bound from Hamburg 
to New York, in May 1854, passed, from daylight to 
noon, twenty-four large “ bergs,” besides several small 
ones, “the whole ocean, as far as the eye could reach, 
being literally covered with them. I should,” he con- 
tinues, “judge the average height of them above the 
surface of the sea to be about sixty feet ; some five or six 
of them were at least twice that height, and, with their 
frozen peaks jutting up in the most fantastic shapes, pre- 
sented a truly sublime spectacle.” 

This “horse-shoe” of cold in the warm water of the 
North Pacific, though extending five degrees farther to- 


——— eee nh ROOD 


1 §$ $$4. 


THE DRIFT OF THE SEA, 387 


ward the south, cannot be the harbour for such icebergs, 
The cradle of those of the Atlantic was perhaps in the 
Frozen Ocean, for they may have come thence through 
Baffin’s Bay. But in the Pacific there is no nursery for 
them. The water in Behring’s Strait is too shallow to 
let them pass from that ocean into the Pacific, and the 
climates of Russian America do not favour the formation 
of large bergs. But, though we do not find in the North 
Pacific the physical conditions which generate icebergs 
like those of the Atlantic, we find them as abundant with 
fogs. The line of separation between the warm and cold 
water assures us of these conditions. 

What beautiful, grand, and benign ideas do we not see 
expressed in that immense body of warm waters which 
are gathered together in the middle of the Pacific and 
Indian Oceans! It is the womb of the sea. In it 
coral islands innumerable have been fashioned, and pearls 
formed in “great heaps;” there, multitudes of living 
things, countless in number and infinite in variety, are 
hourly conceived. With space enough to hold the four 
continents and to spare, its tepid waters teem with nascent 
organisms.* They sometimes swarm so thickly there 
that they change the colour of the sea, making it crim- 
son, brown, black, or white, according to their own hues. 
These patches of coloured water sometimes extend, espe- 


* “Tt is the realm of reef-building corals, and of the wondrously beautiful 
assemblage of animals, vertebrate and invertebrate, that live among them or 
prey upon them. The brightest and most definite arrangements of colour are 
here displayed. It is the seat of maximum development of the majority of 
marine genera. It has but few relations of identity with other provinces. The 
Red Sea and Persian Gulf are its offsets.’—From Professor Forbes’s Paper on 
the “* Distribution of Marine Life.” Plate 31, Johnston's Physical Atlas, 2d 
edit.; Wm. Blackwood and Sons, Edinburgh and London, 1854. 


CHAPTER 
XVI. 


The cradle 
of icebergs 


8 904 


Body of 
warm 
waters in 
the middle 
of the 
Pacific and 
Indian 
Oceans. 


Coloured 
sea-water. 


CHAPTER 
xvi. 


§ 905 


Remark- 
able white 
patch. 


Abstract 
from Capt. 
Kingman's 
log. 


Remark- 
able and 
splendid 
appear- 
ance of 
trater. 


388 THE PHYSICAL GEOGRAPHY OF THE SEA. 


cially in the Indian Ocean, as far as the ‘eye can reach. 
The question, “ What produces them?” is one that has 
elicited much discussion in seafaring circles. The Brus- 
sels Conference deemed them an object worthy of atten- 
tion, and recommended special observations with regard 
to them. 

Captain W. E. Kingman, of the American clipper ship 
the Shooting Star, reports in his last abstract log a re- 
markable white patch, in lat. 8° 46’ south, long. 105° $0’ 
east, and which, in a letter to me, he thus describes :— 

“Thursday, July 27, 1854.—At 7h. 45m. P.M, my 
attention was called to notice the colour of the water, 
which was rapidly growing white. Knowing that we 
were in a much frequented part of the ocean, and having 
never heard of such an appearance being observed before 
in this vicinity, I could not account for it. I imme- 
diately hove the ship to, and cast the lead; had no 
bottom at 60 fathoms. I then kept on our course, tried 
the water by thermometer, and found it to be 78%, the 
same as at 8 AM. We filled a tub, containing some 60 
gallons, with the water, and found that it was filled 
with small luminous particles, which, when stirred, pre- 
sented a most remarkable appearance. The whole tub 
seemed to be active with worms and insects, and looked 
like a grand display of rockets and serpents seen at a 
oreat distance in a dark night; some of the serpents 
appeared to be six inches in Jength, and very luminous. 
We caught, and could feel them in our hands, and they 
would emit light until brought within a few feet of a 
lamp, when, upon looking to see what we had, behold 
nothing was visible! but, by the aid of a sextant’s 


THE DRIFT OF THE SEA. 359 


magnifier, we could plainly see a jelly-like substance 
without colour. At last, a specimen was obtained of 
about two inches in length, and plainly visible to the 
naked eye; it was about the size of a large hair, and 
tapered at the ends. By bringing one end within about 
one-fourth of an inch of a lighted lamp, the flame was 
attracted toward it, and burned with a red light; the 
substance crisped in burning, something like a hair, or 
appeared of a red heat before being consumed. In a glass 
of the water there were several small, round substances 
(say one-sixteenth of an inch in diameter), which had the 
power of expanding to more that twice their ordinary 
size and then contracting again; when expanded, the 
outer rim appeared like a circular saw, only that the 
teeth pointed toward the centre. 

“This patch of white water was about 23 miles in 
Yength north and south, divided near its centre by an 
irregular strip of dark water half a mile wide ; its east 
aud west extent I can say nothing about. 

“JT have seen what is called white water in about all 
the known oceans and seas in the world, but nothing 
that would compare to this in extent or whiteness.  Al- 
though we were going at the rate of nine knots, the ship 
made no noise either at the bow or stern. The whole 
appearance of the ocean was like a plain covered with 
snow. There was scarce a cloud in the heavens, yet the 
sky, for about ten degrees above the horizon, appeared as 
black as if a storm was raging; the stars of the first 
magnitude shone with a feeble light, and the ‘Milky 
Way’ of the heavens was almost entirely eclipsed by that 
through which we were sailing. The scene was one of 


CHAPTER 
xVI1. 


Curious 
animal- 
cule 


Length of 
the pateh 


Its great 
whiteness 


CHAPTER 
XVI. 


Appear- 
ance of the 
sky. 


§ 906 
Causes of 
discolora- 
tion. 


390 THE PHYSICAL GEOGRAPHY OF THE SEA. 


awful grandeur; the sea having turned to phosphorus, 
and the heavens being hung in blackness, and the stars 
going out, seemed to indicate that all nature was prepar- 
ing for that last grand conflagration which we are taught 
to believe is to annihilate this material world. 

“ After passing through the patch, we noticed that the 
sky, for four or five degrees above the horizon, was con- 
siderably illuminated,—something like a faint aurora 
borealis, We soon passed out of sight of the whole con- 
cern, and had a fine night, without any conflagration 
(except of midnight oil, in trying to find out what was 
in the water). I send you this, because I believe you 
request your corps of ‘one thousand assistants’ to furnish 
you with all such items, and I trust it will be acceptable. 
But as to its furnishing you with much, if any, infor- 
mation relative to the insects or animals that inhabit 
the mighty deep, time only will tell; I cannot think it 
will.” 

These discolorations are no doubt caused by organisms 
of the sea, but whether wholly animal or wholly vegetable, 
or whether sometimes the one and sometimes the other, 
has not been satisfactorily ascertained. I have had speci- 


-mens of the colouring matter sent to me from the pink- 


stained patches of the sea, They were animalculz well 
detined. The tints which have given to the Red Sea its 
name may, perhaps, be in some measure due to agencies 
similar to those which, in the salt-makers’ ponds, give a 
reddish cast'to the brine just before it reaches that point 
of concentration when crystallization is to commence. 
Some microscopists maintain that this tinge is imparted 
by the shells and other remains of infusoria which have 


THE DRIFT OF THE SEA. 391 


perished in the growing saltness of the water. The Red 
Sea may be regarded, in a certain light, as the scene of 
natural salt-works on a grand scale. The process is by 
solar evaporation. No rains interfere, for that sea‘is in a 
riverless district, and the evaporation goes on-unceasingly, 
day and night, the year round. The shores are lined with 
incrustations of salt, and the same causes which tinge 
with red’ the brine in the vats of the salt-makers probably 
impart a like hue to the arms and ponds along the shore 
of this sea. Quantities, also, of slimy, red colouring matter 
are, at certain seasons of the year, washed up along the 
shores of the Red Sea; which Dr. Ehrenberg, after an 
examination under the microscope, pronounces to be a 
very delicate kind of sea-weed, From this matter that 
sea derives its name. So also the Yellow Sea. Along 
the coasts of China, yellowish-coloured spots are said not 
to be uncommon. I know of no examination of this 
colouring matter, however. In the Pacific Ocean I have 


CHAPTER 
XVI. 


Red Sea 
a natural 
salt work. 


The Yel- 
low Sea 


often observed these discolorations of the sea. Red - 


patches of water are most frequently met with, but I have 
also observed white or milky appearances, which at night 
I have known greatly to alarm navigators by their being 
taken for shoals, 

These teeming waters bear off through their several 
channels the surplus heat of the tropics, and disperse it 
among the icebergs of the Antarctic. See the immense 
equatorial flow to the east of New Holland. It is bound 
for the icy barriers of that unknown sea, there to temper 
climates, grow cool, and return again, retreshing man and 
beast by the way, either as the Humboldt Current, or the 
ice-bearing current which enters the Atlantic around Cape 


1 § 404, 2 


(74) 
oo 


§ 907 


Equatorial 
flow east of 
New Hol- 
land. 


w) 


392 THE PHYSICAL GEOGRAPHY OF THE SEA. 


© 


cxapter Horn, and changes into warm again as it enters the Gulf 
xVI. 


‘ of Guinea. It was owing to this great southern flow 
he waters 


by which from the coral regions that Captain Ross was enabled to 
the far- 


thestsouth penetrate so much farther south than Captain Wilkes, on 
rearnen. his voyage to the Antarctic; and it is upon these waters 
that that sea is to be penetrated, if ever. The North 
Pacific, except in the narrow passage between Asia and 
America, is closed to the escape of these warm waters 
into the Arctic Ocean. - The only outlet for them is to 
the south. They go down toward the Antarctic re- 
gions to dispense their heat and get cool; and the cold 
of the Antarctic, therefore, it may be inferred, is not so 
bitter as is the extreme cold of the Frozen Ocean of the 

north. 
§908 The warm flow to the south from the middle of the 
Warmflow Tndian Ocean is remarkable. Masters who return their 


mt of abstract logs to me mention sea-weed, which I suppose 
Ocean. to be brought down by this current, as far as 45° south. 
There it is generally, but not always, about 5° warmer 

than the ocean along the same parallel on either side. 
§909 But the most unexpected discovery of all is that of the 
vonw wea Warm flow along the west coast of South Africa, its 
ees junction with the Lagullas current,—called, higher up, the 
Africa Mozambique, —and then their starting off as one stream to 
the southward. The prevalent opinion used to be, that 
the Lagullas current, which has its genesis in the Red 
Sea, doubled the Cape of Good Hope, and then joined the 
great equatorial current of the Atlantic to feed the Gulf 
Stream. But my excellent friend, Lieutenant Marin 
Jansen, of the Dutch Navy, suggested that this was 


probably not the case. This induced a special investiga- 


1 § 440. 


ety | oh tre + 


THE DRIFT OF THE SEA. 393 


tion, and J found as he suggested, and as is represented 
on Plate IX. Captain N. B. Grant, in the admirably well- 
kept abstract log of his voyage from New York to Aus- 
tralia, found this current remarkably.developed. He was 
astonished at the temperature of its waters, and did not 
know how to account for such a body of warm water in 
such a place. Being in longitude 14° east, and latitude 
39° south, he thus writes in his abstract log :— 

“That there is a current setting to the eastward across 
the South Atlantic and Indian Oceans is, I believe, 
admitted by all navigators. The prevailing westerly 
winds seem to offer a sufficient reason for the existence of 
such a current, and the almost constant south-west swell 
would naturally give it a northerly direction, But why 
the water should be warmer here (38° 40’ south) than 
between the parallels of 35° and 37° south, is a problem 
that, in my mind, admits not of so easy solution, especially 
if my suspicions are true in regard to the northerly set. 
I shall look with much interest for a description of the 
‘currents’ in this part of the ocean.” 

In latitude 38° south, longitude 6° east, he found the 
water at 56°. His course thence was a little to the south 
of east, to the meridian of 41° east, at its intersection 
with the parallel of 42° south. Here his water ther- 
mometer stood at 50°, but between these two places it 
ranged at 60°, and upward, being as high on the parallel 
of 39° as 73°. Here, therefore, was a stream—a mighty 
“river in the ocean’—one thousand six hundred miles 
across from east to west, having water in the middle of it 
23° higher than at the sides, This is truly a Gulf 
Stream contrast. What an immense escape of heat from 
the Indian Ocean, and what an influx of warm water into 


CHAPTER 
xvi. 


§ 910 


Remarks 
of Captain 
N.B. Grant 


§ 911 


Indica- 

tions of 
thermo- 
meter, 


CHAPTER 
D-GVLE 


§ 912 


Spasmodie 
efforts of 
the sea. 


§ 913 


Commo- 
tion of the 
sea at un- 
certain in- 
tervals. 


394 THE PHYSICAL GEOGRAPHY OF THE SEA. 


the frozen regions of the south! This streain is not 
always as broad nor as warm as Captain Grant found it. 
At its mean stage it conforms more nearly to the limits 
assigned it in the diagram (Plate IX.). 

Ve have, in the volume of heated water reported by 
Captain Grant, who is a close and accurate observer, an 
illustration of the sort of spasmodic efforts—the heaves 
and throes—which the sea, in the performance of its 
ceaseless task, has sometimes to make. By some means 
the equilibrium of its waters, at the time of Captain 
Grant’s passage, December—the southern summer—1$52, 
appears to have been disturbed to an unusual extent ; 
hence this mighty rush of overheated waters from the 
great inter-tropical caldron of the two oceans down toward 
the south. 

Instances of commotion in the sea at uncertain inter- 
vals—the making, as it were, of efforts by fits and starts 
to keep up to time in the performance of its manifold 


offices—are not unfrequent, nor are they inaptly likened 
to spasms. There are some remarkable throes in the sea, 
which I have not been able wholly to account for. Near 
the equator, and especially on this side of it in the 
Atlantic, mention is made, in the “abstract log,” by 
almost every observer that passes that way, of “ tide- 
rips ;”? which are a commotion in the water not unlike 
that produced by a conflict of tides, or of other powerful 
currents. These “tide-rips” sometimes move along with 
a roaring noise, and the inexperienced navigator always 
expects to find his vessel drifted by them a long way out 
of her course ; but when he comes to cast up his reckoning 
the next day at noon, he remarks with surprise that no 


current has been felt. 


THE DRIFT OF THE SEA. 395 


These tide-rips are usually found in the neighbourhood 
of the equatorial calms, that region of constant precipita- 
tion. And hence, if currents at all,—if so, they are very 
superficial—I have thought they might be streams of 
rain water, which old seamen tell us they have dipped 
up there fresh from the sea, running off. This conjecture, 
however, does not satisfy the phenomenon in all of its 
aspects. It is sometimes described as starting up in a 
calm, and then approaching the vessel with great waves 
and a great noise: it seems threatening enough to excite 
a feeling of apprehension in the minds of seamen, for it 
looks as if it would dash over their frail bark as it lies 
wallowing in the sea, and helplessly flapping its sails 
against the masts. 

Captain Higgins, of the Maria, when bound from New 


o, one of 


York to Brazil, thus describes, in his abstract log, 


these “tide-rips,” as seen by him 10th October 1855, in 
N. lat. 14° W. long. 34° :— 

“At 3 P.M. saw a tide-rip; in the centre, temp. air 
S0°, water 81°. From the time it was seen to wind- 
ward, about three to five miles, until it had passed to 
leeward out of sight, it was not five minutes. I should 
judge it travelled at not less than sixty miles per hour, 
or as fast as the bores of India. Although we have 
passed through several during the night, we do not 
find they have set the ship to the westward any. It 
may be that they are so soon passed that. they have 
no influence on the ship; but they certainly beat very 
hard against the ship’s sides, and jarred her all over. 
They are felt even when below, and will wake one out 
of sleep.” 


CHAPTER 


§ 914 


Tide-rips. 


§ 915 


Descrip- 
tion of 
tide-rip by 
Captain 
Higgins. 


CHAPTER 

XVI. 

§ 916 
Disruption 
of ice, ice- 
bergs, &e. 


396 THE PHYSICAL GEOGRAPHY OF THE SEA. 


But, besides tide-rips, bores, and eagres,* there are the 
sudden disruption of the ice which arctic voyagers tell of, 


* The bores of India, of the Bay of Fundy, and the Amazon, are the most 
celebrated, They are a tremulous tidal-wave, which, at stated periods, comes 
rolling in from the sea, threatening to overwhelm and engulf everything that 
moves on the beach. This wave is described, especially in the Bay of Fundy, as 
being many feet high; and it is said oftentimes to overtake deer, swine, and 
other wild beasts that feed or lick on the beach, and to swallow them up before 
the swiftest of foot among them have time to escape. The swine, as they feed on 
mussels at low water, are said to snuff the ‘‘ bore,” either by sound or smell, 
and sometimes to dash off to the cliffs before it rolls in. 

The eagre is the bore of Tsien-Tang river. It is thus described by Dr. Mac- 
gowan, ina paper before the Royal Asiatic Society, 12th January, 1853, and as 
seen by him from the city of Hang-chau in 1848 :— 

“ At the upper part of the bay, and about the mouth of the river, the eagre is 
scarcely observable ; but, owing to the very gradual descent of the shore and tlie 
rapidity of the great flood and ebb, the tidal phenomena even here present 
a remarkable appearance. Vessels which, a few moments before, were afloat, 
are suddenly left high and dry on a strand nearly two miles in width, which the 
returning wave as quickly floods. It is not until the tide rushes beyond thie 
mouth of the river that it becomes elevated to a lofty wave constituting the eagre, 
which attains its greatest magnitude opposite the city of Hang-chau. Generally 
there is nothing in its aspect, except on the third day of the second month and 
on the eighteenth of the eighth, or at the spring-tide, about the period of tlie 
vernal and autumnal equinoxes, its great intensity being at the latter season. 
Sometimes, however, during the prevalence of easterly winds, on the third day, 
after the sun and moon are in conjunction, or in opposition, the eagre courses up 
the river with hardly less majesty than when paying its ordinary periodical visit. 
On one of these unusual occasions, when I was travelling in native costume, I 
had an opportunity of witnessing it, on December 14th, 1848, at about 2 p.m. 

“ Between the river and the city walls, which are a mile distant, dense suburbs 
extend several miles along the banks. As the hour of flood-tide approached, 
crowds gathered in the streets, running at right angles with the Tsien-Tang, but 
at safe distances. My position was a terrace in front of the Tr1-wave Temple, 
which afforded a good view of the entire scene. Ona sudden all traffic in the 
thronged mart was suspended, porters cleared the front street of every descrip- 
tion of merchandise, boatmen ceased lading and unlading their vessels, and put 
out in the middle of the stream ; so that a few moments sufficed to give a deserted 
appearance to the busiest part of one of the busiest cities of Asia. The centre 
of the river teemed with craft, from small boats to huge barges, including the 
gay ‘flower-hoats.’ Loud shouting from the fleet announced the appearance of 
the flood, which seemed like a glistening white cable, stretched athwart the river 
at its mouth, as far down as the eye could reach. Its noise, compared by Chinese 
poets to that of thunder, speedily drowned that of the boatmen ; and, as it ad- 
vanced with prodigious velocity,—at the rate, I should judge, of twenty-five miles 
an hour,—it assumed the appearance of an alabaster wall, or, rather, of a cata- 
ract four or five miles across aud about thirty feet high, moving bodily onward. 


THE DRIFT OF THE SEA. 397 


the immense bergs which occasionally appear in groups carrer 
. : . AVI. 
near certain latitudes, the variable character of all the — 


Soon it reached the advanced guard of the immense assemblage of vessels awaiting 
its approach. Knowing that the bore of the Hooghly, which scarcely deserved 
mention in connection with the one before me, invariably overturned boats which 
were not skilfully managed, I could not but feel apprehensive for the lives of the 
floating multitude. As the foaming wall of water dashed impetuously onward, 
they were silenced, all being intently occupied in keeping their prows toward the 
wave, which threatened to submerge everything afloat ; but they all vaulted, as it 
were, to the summit with perfect safety. The spectacle was of greatest interest 
when the eagre had passed about one half way among the craft. On one side 
they were quietly reposing on the surface of the unruffled stream, while those on 
the nether portion were pitching and heaving in tumultuous confusion on the 
flood; others were scaling with the agility of salmon the formidable cascade. 
This grand and exciting scene was but of a moment’s duration,—it passed up the 
river in an instant; but from this point with gradually diminishing force, size, 
and velocity, until it ceased to be perceptible, which Chinese accounts represent 
to be eighty miles distant from the city. From ebb to flood tide the change was 
almost instantaneous: a slight flood continued after the passage of the wave, but 
it soon began to ebb. Having lost my memoranda, I am obliged to write from 
recollection. My impression is, that the fall was about twenty feet; the Chi- 
nese say that the rise and fall is sometimes forty feet at Hang-chau. The maxi- 
mum rise and fall at spring-tides is probably at the mouth of the river, or upper 
part of the bay, where the eagre is hardly discoverable. In the Bay of Fundy, 
where the tides rush in with amazing velocity, there is at one place a rise of 
seventy feet ; but there the magnificent phenomenon in question does not appear 
to be known at all. It is not, therefore, where tides attain their greatest rapi- 
dity, or maximum rise and fall, that this wave is met with, but where a river 
and its estuary both present a peculiar configuration. 

“‘ Dryden’s definition of an eagre, appended in a note to the verse above quoted 
from the Threnodia Augustalis, is, ‘a tide swelling above another tide,’ which he 
says he had himself observed in the River Trent. Such, according to Chinese oral 
accounts, is the character of the Tsien-Tang tides: a wave of considerable height 
rushes suddenly in from the bay, which is soon followed by one much larger. 
Other accounts represent three successive waves riding in; hence the name of the 
temple mentioned, that of the Three Waves. Both here and on the Hooghly I 
observed but one wave; my attention, however, was not particularly directed to 
this feature of the eagre. The term should, perhaps, be more comprehensive, 
and express ‘the instantaneous rise and advance of a tidal wave ;’ the Indian 
barbarism, ‘bore,’ should be discarded altogether. 

“A very short period elapsed between the passage of the eagre and the 
resumption of traffic. The vessels were soon attached to the shore again; women 
and children were occupied in gathering articles which the careless or unskilful 
had lost in the aquatic melée. The streets were drenched with spray, and a 
considerable volume of water splashed over the banks into the head of the grand 
canal, a few feet distant.”—Vide Zransactions of Chinese Branch of the Royal 
Asiatic Society. 


CHAPTER 
XVI. 


Recession 
of the sea. 


Sa 


The Gulf 
Stream a 
pulse ir. 
the sea. 


§ 918 


Warm wa- 


ter flows 
compared 


to circula- 
tion of the __ 


blond. 


398 THE PHYSICAL GEOGRAPHY OF THE SEA 


currents of the sea,—now fast, now slow, now running 
this way, then that,—all of which may be taken as so 
many signs of the tremendous throes which occur in the 
bosom of the ocean. Sometimes the sea recedes from 
the shore, as if to gather strength for a great rush against 
its barriers ; as it did when it fled back to join with the 
earthquake and overwhelm Callao in 1746, and again 
Lisbon nine years afterward. The tide-rips in mid ocean, 
the waves dashing against the shore, the ebb and flow of 
the tides, may be regarded, in some sense, as the throb- 
bings of the great sea pulse. 

The motions of the Gulf Stream; beating time for the 
ocean and telling the seasons for the whales, also suggest 
the idea of a pulse in the sea, which may assist us in 
explaining some of its phenomena. At one beat there 
is a rush of warm water from the equator toward the 
poles, at the next beat a flow from the poles toward the 
equator. This sort of pulsatior. is heard also in the 
howling of the storm and the whistling of the wind; 
the needle trembles unceasingly to it, and tells us of 
magnetic storms of great violence, which at times extend 
over large portions of the earth’s surface; and when we 
come to consult the records of those exquisitely sensitive 
anemometers, which the science and ingenuity of the age 
have placed at the service of philosophers, we find there 
that the pulse of the atmosphere is never still: in what 
appears to us the most perfect calm, the recording pens of 
the automatic machine are moving to the pulses of the air. 

Now, if we may be permitted to apply to the Gulf 
Stream, and to the warm flows of water from the Indian 
Ocean, an idea suggested by the functions of the human 


— ——  —eeEeEeEeeEEEeeEeeeeEeEeESEeEee 


THE DRIFT OF THE SEA. 399 


heart in the circulation of the blood, we perceive how 
these pulsations of the great sea-heart may perhaps assist 
in giving circulation to its waters through the immense 
system of aqueous veins and arteries that run between 
the equatorial and polar regions. The waters of the Gulf 
Stream, moving together in a body’ through such an 
extent of ocean, and being almost impenetrable to the 
cold waters on either side,—which are, indeed, the banks 
of this mighty river,—may be compared to a wedge- 
shaped cushion placed between a wall of waters on the 
right and a wall of waters on the left. If now we ima- 
gine the equilibrium of the sea to be disturbed by the 
heating or cooling of its waters to the right or the left 
of this stream, or the freezing or thawing of them in any 
part; or if we imagine the disturbance to take place by 
the action of any of those agencies which give rise to the 
motions which we have called the pulsations of the sea; 
we may conceive how it might be possible for them 
to force the wall of waters on the left to press this 
cushion down toward the south, and then again for the 
wall on the right to press it back again to the north, as 
we have seen that it is.” 

Now the Gulf Stream, with its head in the Straits of 
Florida, and its tail in the midst of the ocean, is wedge- 
shaped ; its waters cling together, and are pushed to and 
fro—squeezed, if you please—by a pressure, now from 
the right, then from the left, so as to work-the whole 
wedge along between the cold liquid walls which contain 
it. May not the velocity of this stream, therefore, be in 
some sort the result of this working and twisting, this 
peristaltic force in the sea ? 


~ 
un 
— 
2 
vez) 
oO 
— 
7) 
“rR 
bait 
or 


CHAPTER 
XVI. 


Gulf 
Streaun 


§ 919 


Continued 


CHAPTER 
XVI. 


§ 920 
Two lobes 
of polar 
water 
stretching 
up from 
the south 
into Indian 
Ocean. 


Compari- 
son to 
functions 
of the hu- 
man heart. 


400 THE PHYSICAL GEOGRAPHY OF THE SEA, 


In carrying out the views suggested by the idea of 
pulsations in the sea, and their effects in giving dynami- 
cal force to the circulation of its waters, attention may 
be called to the two lobes of polar waters that stretch 
up from the south into the Indian Ocean, and which are 
separated by a feeble flow of tropical waters. Icebergs 
are sometimes met with in these polar waters as high up 
as the parallel of the fortieth degree of latitude. Now, 
considering that this tropical flow in mid-ocean is not 
constant,—that many navigators cross the path assigned 
to it in the plate without finding their thermometer to 
indicate any increase of heat in the sea; and considering, 
therefore, that any unusual flow of polar waters, any 
sudden and extensive disruption of the ice there, sufficient 
to cause a rush of waters thence, would have the effect of 
closing for the time this mid-ocean flow of tropical waters ; 
we are entitled to infer that there is a sort of conflict at 
times going on in this ocean between its polar and equa- 
torial flows of water. For instance, a rush of waters 
takes place from the poles toward the equator. The 
two lobes close, cut off the equatorial flow between them, 
and crowd the Indian Ocean with polar waters. They 
press out the overheated waters ; hence the great equa- 
torial flow encountered by Captain Grant. 

Thus this opening between the cold-water lobes ap- 
pears to hold to the chambers of the Indian Ocean, with 
their heated waters, the relations which the valves and 
the ventricles of the human heart hold to the circulation 
of the blood. The closing of these lobes at certain times 
prevents regurgitation of the warm waters, and compels 
them to pass through their appointed channels. 


THE DRIFT OF THE SEA. 401 


From this point of view, how many new beauties 


CHAPTER 
XVI1. 


now begin to present themselves in the machinery of _— 


the ocean! its great heart not only beating time to the 
seasons, but palpitating also to the winds and the rains, 
to the cloud and the sunshine, to day and night.’ Few 
persons have ever taken the trouble to compute how 
much the fall of a single inch of rain over an extensive 
region in the sea, or how much the change even of two 
or three degrees of temperature over a few thousand 
square miles of its surface, tends to disturb its equili- 
brium, and consequently to cause an aqueous palpitation 
that is felt from the equator to the poles. Let us illus- 
trate by an example: The surface of the Atlantic Ocean 
covers an area of about twenty-five millions of square 
miles. Now, let us take one-fifth of this area, and sup- 
pose a fall of rain one inch deep to take place over it. 
This rain would weigh three hundred and sixty thousand 
millions of tons; and the salt which, as water, it held in 
solution in the sea, and which, when that water was 
taken up as vapour, was left behind to disturb equili- 
brium, weighed sixteen millions more of tons, or nearly 
twice as much as all the ships in the world could carry 
at a cargo each. It might fall in an hour, or it might 
fall in a day; but, occupy what time it might in falling, 
this rain is calculated to exert so much force—which is 
inconceivably great—in disturbing the equilibrium of the 
ocean. If all the water discharged by the Mississippi 
River during the year were taken up in one mighty 
measure, and cast into the ocean at one effort, it would 
not make a greater disturbance in the equilibrium of the 
sea than would the fall of rain supposed. Now this is 


1 § 864. 
26 


§ 921 
Refiec- 
tions. 


Great 
effects pro- 
duced by 
apparently 
slight 
causes. 


Tilustra- 
tien. 


Mississippi, 


CHAPTER 
XVI. 


Arca of the 
Atlantic. 


§ 922 


Effects of 
diurnal 
changes in 
tempera- 
ture. 


4.()2 THE PHYSICAL GEOGRAPHY OF THE SEA. 


for but one-fifth of the Atlantic, and the area of the 
Atlantic is about one-fifth of the sea-area of the world; 
and the estimated fall of rain was but one inch, whereas 
the average for the year is’ sixty inches, but we will 
assume it for the sea to be no more than thirty inches. 
In the ageregate, and on an average, then, such a dis- 
turbance in the equilibrium of the whole ocean as is here 
supposed occurs seven hundred and fifty times a year, or 
at the rate of once in twelve hours. Moreover, when it 
is recollected that these rains take place now here, now 
there ; that the vapour of which they were formed was 
taken up at still other places; we shall be enabled to 
appreciate the better the force and the effect of these 
pulsations in the sea. 

Between the hottest hour of the day and the coldest 
hour of the night there is frequently a change of four 
degrees in the temperature of the sea.* Let us, there- 
fore, the more thoroughly to appreciate the throbbings of 
the sea-heart which take place in consequence of the 
diurnal changes in its temperature, call in the sunshine, 
the cloud without rain, with day and night, and their 
heating and radiating processes. And to make the case 
as strong as to be true to nature we may, let us again 
select one-fifth of the Atlantic Ocean for the scene of 
operation, The day over it is clear, and the sun pours 
down his rays with their greatest intensity, and raises 
the temperature two degrees. At night the clouds inter- 
pose, and prevent radiation from this fifth; whereas the 
remaining four-fifths, which are supposed to have been 
screened by clouds, so as to cut off the heat from the sun 


* Vide Admiral Smyth’s Memoir of the Mediterranean, p. 125. 
1 § 208. 


THE DRIFT OF THE SEA. 403 


during the day, are now looking up to the stars in a omapren 
cloudless sky, and serve to lower the temperature of the aoe 
surface-waters, by radiation, two degrees. Here, then, is 

a difference of four degrees, which we will suppose extends 

only ten feet below the surface. The total and absolute 
change made in such a mass of sea water, by altering its 
temperature two degrees, is equivalent to a change in its 
volume of three hundred and ninety thousand millions of 

cubic feet. 

Do not the clouds, night and day, now present them- § 923 
selves to us in a new light? They are cogs, and rachets, ©ouds 
and wheels, in that grand and exquisite machinery which 
governs the sea, and which, amid all the jarring of the 
elements, preserves in harmony the exquisite adaptations 
of the ocean. 

It seems to be a physical law, that cold-water fish are § 924 
more edible than those of warm water. Bearing this fact Coltwater 


fish are 


in mind as we study Plate IX., we see at a glance the™r 
ediblethan 


places which are most favoured with good fish markets. tos ef 
Both shores of North America, the east coast of China, with water. 
the west coasts of Europe and South America, are all washed 
by cold waters; and therefore we may infer that their mav- 
kets abound with the most excellent fish. The fisheries 
of Newfoundland and New England, over which nations 
have wrangled for centuries, are in the cold water from 
Davis’ Strait. The fisheries of Japan and Eastern China, 
which almost, if not quite, rival these, are situated also 
in the cold water. 

Neither India, nor the east coasts of Africa and South 
America, where the warm waters are, are celebrated for 


their fish. 


Three thousand American vessels, it is said, are en- § 925 


404 THE PHYSICAL GEOGRAPHY OF THE SEA. 


carrer gaged in the fisheries. If to these we add the Dutch, 


xvVI. 


soak French, and English, we shall have a grand total, per- 

gaged in haps, of not less than six or eight thousand, of all sizes 

eae Sind flags, engaged in this one pursuit. Of all the indus- 
trial pursuits of the sea, however, the whale fishery is 

Map tar the most valuable. Wherefore, in treating of the physi- 
cal geography of the sea, a map for the whales would be 
useful. 

§926 The sperm whale is a warm-water fish. The right 
Watersin whale delights in cold water. An immense number of 
whats ar@ log-books of whalers have been discussed at the National 

Observatory, with the view of detecting the parts of the 
ocean in which the whales are to be found at the differ- 
ent seasons of the year. Charts showing the result have 
been published ; they form a part of the series of Maury’s 
Wind and Current Charts. 


§927 In the course of these investigations, the discovery was 
Conse- 
quences of 


tempera- of fire, through which he cannot pass; that the right 
ture in re- f=) 


gard to whale of the northern hemisphere, and that of the south- 


made that the torrid zone is, to the right whale, as a sea 


ern, are two different animals ; and that the sperm whale 
has never been known to double the Cape of Good Hope 
—he doubles Cape Horn. 

§ 928 With these remarks, and the explanations given on 
Plate IX., the parts of the ocean to which the right 
whale most resorts, and the parts in which the sperm 
are found, may be seen at a glance. 


STCRMS. 405 


CHAPTER XVII. 


STORMS. 


Data for Plate V., § 929.—Typhoons, 936.—Monsoons in the China Sea, 937.— 
Mauritius Hurricanes, 938.—West India ditto, 939.—Jansen on Hurricanes 
and Cyclones, 940.—Extra-tropical Gales, 950.—The Steamer San Franciseo’s 
Gale, 951.—More Rains, Gales, &c., in the North than in the South Atlantic 
(Plate XIII.), 956. 


PLATE V. is constructed from data furnished by the omaprer 
3 : XVII. 

Pilot Charts, as far as they go, that are in process of con- _— 

struction at the National Observatory. For the Pilot Seas 


Charts, the whole ocean is divided off into “ fields” or Pit’ 
‘ Pilot 


districts of five degrees square; 7. e., five degrees of lati- C™s" 
ude by five degrees of longitude, as already explained on 

page xii. Now in getting out from the log-books materials 

for showing, in every district of the ocean, and for every 
month, how navigators have found the winds to blow, it 

has been assumed that, in whatever part of one of these 
districts a navigator may be when he records the direc- 

tion of the wind in his log, from that direction the wind 

was blowing at that time all over that district; and this 

is the only assumption that is permitted in the whole 
course of investigation. 

Now, if the navigator will draw, or imagine to be § 930 

drawn, in any such district, twelve vertical columns for “!nvesti- 


i e gating 
the twelve months, and then sixteen horizontal lines eae 
of whic 
through the same for the sixteen points of the compass,— “Pilot 
Charts” 


i. €. for N., N.N.E., N.E, E.N.E,, and so on, omitting were 

the by-points,—he will have before him a picture of the aie 
“ Investigating Chart,” out of which the “ Pilot Charts” 
are constructed. In this case, the alternate points of the 


compass only are used, because, when sailing free, the 


CHAPTER 
XVII. 


§ 931 


Explana- 
tion of 

“ fives and 
tallies.” 


§ 932 


Reference 


_ to Plate V. 


406 THE PHYSICAL GEOGRAPHY OF THE SEA. 


direction of the wind is seldom given for such points as 
N. by E.,, W. by 8., &c. Moreover, any attempt, for the 
present, at greater nicety would be over-refinement ; for 
navigators do not always make allowance for the aber- 
ration of the wind; in other words, they do not allow 
for the apparent change in the direction of the wind 
caused by the rate at which the vessel may be moving 
through the water, and the angle which her course makes 
with the true direction of the wind. JBearing this ex- 
planation in mind, the intelligent navigator will have no 
difficulty in understanding the wind diagram (Plate V.), 
and in forming a correct opinion as to the degree of credit 
due to the fidelity with which the prevailing winds of 
the year are represented on Plate VIII. 

As the compiler wades through log-book after log-book, 
and scores down in column after column, and upon line 
after line, mark upon mark, he at last finds that, under 
the month, and from the course upon which he is about 
to make an entry, he has already made four marks or 
scores, thus ({{1]). The one that he has now to enter 
will make the fifth; and he “scores and tallies,” and so 
on, until all the abstracts relating to that part of the 
ocean upon which he is at work have been gone over, and 
his materials exhausted. These “ fives and tallies” are 
exhibited on Plate V. 

Now, with this explanation, it will be seen that in the 
district marked A (Plate V.), there have been examined 
the logs of vessels that, giving the direction of the wind 
for every eight hours, have altogether spent days enough 
to enable me to record the calms and the prevailing direc- 
tion of the winds for eight hours, 2144 times: of these, 
285 were for the month of September ; and of these 285 
observations for September the wind is reported as pre- 


STORMS. 407 


vailing for as much as eight hours at a time: from N., cnarrer 
seemed trom NIN 1; NE 2; EN.E., 1; BE, 0; rab 
Poel Sh, 45° SS:HS 23°8.,°25; SSW. 45; 

5.W., 935 W.S.W., 24.; W., 47; W.N.W., 17; N.W,, 15; 
N.N.W., 1; Calms, 5 ;—total, 285 for this month in this 
district. 

The number expressed in figures denotes the whole 
number of observations of calms and winds together that 
are recorded for each month and district. 

In C, the wind in May sets one-third of the time from § 934 
west. But in A, which is between the same parallels, eo 
the favourite quarter for the same month is from south 
to south-west, the wind setting one-third of the time for 
that quarter, and only 10 out of 221 times from the 
west ; or, on the average, it blows from the west only 
13 day during the month of May. 

In B, notice the great “Sun Swing” of the winds in § 935 
September, indicating that the change from summer to {Su 


Swing "’o 
winter, in that region, is sudden and violent ; from winter wins i 
to summer, gentle and gradual. 

In some districts of the ocean, more than a thousand Names of 
observations have been discussed for a single month ; tions mace 
whereas, with regard to others, not a single record is to 
be found in any of the numerous log-books at the National 
Observatory. | 

TypHoons.—The China Seas are celebrated for their § 936 
furious gales of wind, known among seamen_as typhoons Tsphoons 
and white squalls. These seas are included on the plate Se 
(VIII.) as within the region of the monsoons of the Indian 
Ocean. But the monsoons of the China Sea are not five- 
month monsoons;’ they do not prevail from the west of 


south for more than two or three months, 


2 § 788. 


CHAPTER 
XVII. 


§$ 937 
Monsoons 
as ex- 
hibited on 
Plate V. 


Arid plains 
ot Asia. 


§ 938 


Time of 
Mauritius 
hurricanes 
and 
cyclones 
of Indian 
Ocean. 


§ 939 
West and 
East India 
hurricanes 


408 THE PHYSICAL GEOGRAPHY OF THE SEA. 


Plate V. exhibits the monsoons very clearly in a part 
of this sea. In the square between 15° and 20° north, 
110° and 115° east, there appears to be a system of three 
monsoons ; that is, one from north-east in October, Novem- 
ber, December, and January ; one from east in March and 
April, changing in May ; and another from the southward 
in June, July, and August, changing in September. The 
great disturber of the atmospheric equilibrium appears to 
be situated among the arid plains of Asia ; their influence 
extends to the China Seas, and about the changes of the 
monsoons these awful gales, called typhoons and white 
squalls, are experienced. 

In like manner, the Mauritius hurricanes, or the 
cyclones of the Indian Ocean, occur during the unsettled 
state of the atmospheric equilibrium which takes place at 
that debatable period during the contest between the 
trade-wind force and the monsoon force; and which 
debatable period occurs at the changing of the monsoon, 
and before either force has completely gained or lost the 
ascendency. At this period of the year, the winds, break- 
ing loose from their controlling forces, seem to rage with 
a fury that would break up the very fountains of the 
deep. 

So, too, with the West India hurricanes of the Atlantic. 
These winds are most apt to occur during the months of 
August and September. There is, therefore, this remark- 
able difference between these gales and those of the East 
Indies: the latter occur about the changing of the mon- 
soons, the former during their height. In August and 
September, the south-west monsoons of Africa’ and the 
south-east monsoons of the West Indies’ are at their 


§ 796. 2 $810, 8 § 787. 


STORMS. 409 


height; the agent of one drawing the north-east trade- cuarren 
winds from the Atlantic into the interior of New Mexico —~ 
and Texas, the agent of the other drawing them into the 
interior of Africa, Its two forces, pulling in opposite 
directions, assist now and then to disturb the atmospheric 
equilibrium to such an extent that the most powerful re- 
vulsions in the air are required to restore it. 

“The hurricane season in the North Atlantic Ocean,” § 940 
says Jansen, “ occurs simultaneously with the African goneals 
monsoons ; and in the same season of the year in which Gain 
the monsoons prevail in the North Indian Ocean, in the 
China Sea, and upon the western coast of Central America, 
all the seas of the northern hemisphere have the hurri- 
cane season, On the contrary, the South Indian Ocean 
has its hurricane season in the opposite season of the 
year, and when the north-west monsoon prevails in the 
East Indian Archipelago. 

“Tn the South Pacific and in the South Atlantic, so § 941 
far as I know, rotatory storms are never known, and these ee 
seas have no monsoons. Such a coincidence of hurricanes 24 South 


with monsoons, and of the hurricane-season with the mon- eo 
soon-season, is not without signification. It ever gives 
rise to the thought that the one disturbance causes the 
other ; and however terrible the hurricanes may be to us, 
however disastrous they may appear, yet we are compelled 
to acknowledge therein the healthful working of Nature, 
which is compensating over all and in all. We need 
not, then, doubt that these revolving storms have a 
determinate task to perform in the economy of nature 
—a task which they cannot otherwise fulfil save by 
rotations ; and certainly it is good that they restore in 


Revolving 
storms. 


410 THE PHYSICAL GEOGRAPHY OF THE SEA, 


cnaprer proportion to the terrible power wherewith they are 
XVII. 


intrusted. 

§94g “We do not know all the disturbances which are 
pe caused by the land in the condition of the atmosphere. 
thunder. The way of the lightning of the thunder’ is to us all 
unknown. ‘The circulating channels of electricity are as 
yet hidden in a deep night. 


§943 “Neither do we know what influence the land and the 


Remarks warm currents in the sea have thereon,—even less than we 


on the 
usesof know what operations are appointed for the hurricanes in 


a the economy of nature ; but that they, in their way, have 
important services to perform, cannot be doubted. The 
almighty and merciful Wisdom, whom we find universally 
in all the operations of nature, assures us thereof—is to 
us a pledge. The fact that the hurricanes prefer to place 
their feet in warm water, and that in all seas where they 
prevail warm settled currents are also found, which appear 
to arise from the disturbance which the solid crust of the 
earth causes in the regular flowing of the waters of the 
sea, causes us to suspect that there is a certain relation 
between the hurricanes and the warm currents; and, 

Hurri- finally, that in the economy of nature the hurricanes in 


canes and 


warm the atmosphere and the warm ‘rivers in the sea’ work 
water cur- 


rents work together to restore the disturbed equilibrium in nature, 
hes which can be done in no other way than this, and along 
the way which they, as it were, mutually agree to follow 
together. Thus we see the hurricanes beyond the tropics 
follow the most prevailing current of air along the 
surface, on one side from the south-west, on the other 
side from the north-west; just as the Gulf Stream flows 


to the north and east, and the warm currents of the South 


STORMS. 411 


Indian Ocean to the south and east, and, again, the China cuarrer 
current to the north and east. In this we see, again, the dts 
universal laws by which all matter is governed: very 
touching is the simplicity of the divine plan. 

“When the hurricanes and the ‘rivers in the sea,’ § 944 
upon their way to the poles, have reached the parallel of Ffect of 


diurnal re- 
latitude upon which the effort of the diurnal revolution eee of 


of the earth upon her axis causes air and water to be a ste 
forced in a north-easterly or south-easterly direction, then | 
they bow themselves submissively to the law, and go 
together, often hand in hand, to accomplish their appointed 
tasks. And now, if we suppose that by the diurnal 
revolution everything which moves from the equator to 
this parallel of latitude is bent more gradually to the 
east, then it is remarkable that the first part of the course 
of circulating storms often stands perpendicular to these 
supposed movements of the air, and in the North Atlantic 
Ocean runs nearly W.N.W.; in the South Indian Ocean, 
Wes. Ww, 


“Hurricanes are sometimes observed upon the limits § 945 


of the African monsoon, and upon the limits of the mon- Wer 24 
} . Ake s x *  ricanes 
soon of the East Indian Archipelago. In this Archi- ORe 


pelago hurricanes or right heavy spouts are seldom seen, °*'¥¢4- 
However, hurricanes have been observed in the southern 
hemisphere, between 88° and 90° east longitude. They 
are also found in September in 13° north latitude and 
29° west longitude, and in 16° 33’ north latitude and 
24° 20’ west longitude; the latter also in 18° north lati- 
tude and 25° west longitude, and in 16° 80’ north lati- 
tude and 26° 40’ west longitude;* yet not in the mon- 


* Redfield. 


OHAPTER 
XVII. 


— 


§ 946 


Combats 
in the air 
conse- 
quent 

on the 
changing 
of spring 
and 
autumn. 


Cause of 
Whirlwind 


412 THE PHYSICAL GEOGRAPHY OF THE SEA. 


soon—so much is known to me—but right upon its 
limits; also 7m the equatorial belt which wavers about 
the monsoon, and which becomes narrower and narrower 
as it recedes from the equator. 

“ Now, when we remember what is said’ of the spring 
changing in the southern hemisphere, which agrees with 
the autumnal changing in the northern hemisphere, and 
think of the combat which is then so manifestly waged 
between the various currents of air and the numerous 
spouts which arise in the East Indian Archipelago by the 
aid of small groups of islands, then we shall be less sur- 
prised to find a similar effect produced upon the limit of 
the African monsoon, especially when it pushes the equa- 
torial belt of calms quite over to a portion of the Cape 
Verd Islands. When we take into account that this belt 
becomes narrower and narrower as it is removed from 
the equator ; that also the different currents of air, which 
draw in opposite directions, lie closer to each other; that 
the south-west and north-west winds approach very near 
to each other, and that the latter, in August and Sep- 
tember, are deflected out of their course by the heights 
of the Cape Verd Islands ;—then not much more is neces- 
sary to enable one to comprehend why a wind which, 
coming from the north-east, and veering by the north 
around to the north-west, should, as it meets the south- 
west winds, make a complete revolution, and in so doing 
form a whirlwind, which would go travelling through 
the north-east and south-east trade-winds, especially when 
the moisture and electricity of these air-currents are dif- 
ferent, as is generally the case. And seeing also that 
the north-east trade-wind, as it draws more and more 


1 § 820. 


STORMS. 413 


toward the north, lies to the left of the south-west 
monsoon, it may be readily conceived why the motion 
of this whirl should be from the right hand to the 
left, or contrary to the movements of the hands of a 
watch. 

“Thus, when upon the limit of the African monsoon a 
circular motion in the air arises, we may infer, from the 
situation of the currents of air, and their relation to each 
other, that the movement will be from the right side to 
the left. For the same reason, the motion in the south- 
ern hemisphere, in the South Indian Ocean, is from ‘the 
left hand to the right. Near the north pole we find the 
currents of air just the other way; the south-east, or the 
south-west turned back south-east, is to the left of the 
north-west monsoon. Therefore, when a circular motion 
there takes place upon the limit of the monsoon, it must 
go from the left hand to the right, or with the hands of 
a watch. 

“The want of knowledge prevents me from venturing 
to penetrate into the ‘hidden chambers out of which the 
whirlwind comes,’ for the circulation of the atmosphere 
must, like the revolutions of human society, bring all the 
natural forces into commotion, and they, in the strife 
which they wage, become renewed and strengthened to 
perform their appointed work for the universal welfare, 
and pass away like the all-destroying meteor, after having 
accomplished its terror-awaking mission, The strife—if, 
indeed, I may call the opposite workings in nature strife 
—is violent, terrible. The monsoon has attained its 
greatest strength, the disturbance in the circulation of 
the atmosphere has reached its utmost limits, the vapour 


CHAPTER 
XVII. 


§ 947 


Circular 
motions of 
the winds 
in various 
circum- 
stances, 


§ 948 


Tmpossi- 
bility of 
arriving at 
definite 
conclu- 
sions, 


414 THE PHYSICAL GEOGRAPHY OF THE SEA. 


cuapter and the heavy clouds act in harmony no longer, and with 

a wild violence the uproar, nursed in silence, breaks forth. 

‘The way for the lightning of the thunder’ appears to be 
broken up. 

§949 “Inthe South Indian Ocean (25° south latitude), a 
pias hurricane, accompanied by hail, was observed,* by which 
Suit several of the crew were made blind, others had their 
Ocean, faces cut open, and those who were in the rigging had 

their clothes torn off from them. The master of the ship 
compares the sea ‘to a hilly landscape in winter, covered 
with snow.’ Does it not appear as if the ‘treasures of 
the hail’ were opened, which were ‘reserved against the 
time of trouble, against the day of battle and war?’ ”+ 

§950 ExTraA-TROPICAL GALES.—TIn the extra-tropical regions 
Furious of each hemisphere furious gales of wind also occur. 


gales in : 7 
the extra- One of these, remarkable for its violent effects, was en- 


waite countered on the 24th of December 1853, about three 

hundred miles from Sandy Hook, latitude 39° north, 

Wreck. longitude 70° west, by the San Francisco steam-ship- 

That ship was made a complete wreck in a few moments, 

and she was abandoned by the survivors, after incredible 

hardships, exertions, and sufferings. Some months after 

this disaster, I received by the California mail the abstract 

log of the fine clipper-ship Eagle Wing (Ebenezer H. Lin- 

nell), from Boston to San Francisco. She encountered the 
ill-fated steamer’s gale, and thus describes it :— 

§951 “December 24, 1853—Latitude 39° 15’ north, longi- 


Extract tude 62° 32’ west. First part threatening weather; short- 
from log of EE ee 


Sle ae * The Rhijin, Captain Brandligt. 
+ Natuurkiindige Beschryving der Zeeén, door M. F. Maury, LL.D., Luiten- 
ant der Nord Amerikaansche Marine, vertaald door M. H. Jansen, Luitenant 


ter Zee. Dordrecht, P. K. Braat, 1855. 


~ 
wm 
i 


STORMS. 415 


ened sail. At 4 P.M. close-reefed the top-sails and furled 
the courses. At 8 P.M. took in fore and mizzen top-sails; 
hove to under close-reefed main top-sail and spencer, the 
ship lying with her lee rail under water, nearly on her 
beam-ends, At 1 30 AM. the fore and main top-gallant- 
masts went over the side, it blowing a perfect hurricane. 
At 8 A.M. moderated; a sea took away jib-boom and 
bowsprit-cap. In my thirty-one years’ experience at sea, 
I have never seen a typhoon or hurricane so severe. Lost 
two men overboard; saved one. Stove sky-light, broke 
my barometer, &., &ec.” 

Severe gales in this part of the Atlantic—. ¢., on the 
polar side of the calm belt of Cancer—rarely occur during 
the months of June, July, August, and September. This 
appears to be the time when the fiends of the storm are 
most busily at work in the West Indies. During the 
remainder of the year, these extra-tropical gales, for the 
most part, come from the north-west; but the winter is 
the most famous season for these gales. That is the 
time when the Gulf Stream has brought the heat of sum- 
mer, and placed it'in closest proximity to the extremest 
eold of the north; and there would, therefore, it would 
seem, be a conflict between these extremes; consequently, 
great disturbances in the air, and a violent rush from the 
cold to the warm. 

In like manner, the gales that most prevail in the 
extra-tropics of the southern hemisphere come from the 
pole and the west,—4. e., south-west. 

Storm and Rain Charts for the Atlantic Ocean have 
already been published by the Observatory, and others 
for the whole seas are in process of construction. The 


1 § 84, 


CHAPTER 
XVII. 


—— 


§ 952 


Time when 
severe 
gales sel- 
dom occur 
in particu- 
lar part of 
Atlantic. 


§ 953 


§ 954 - 
Storm and 
Rain 
Charts for 
the Atlan- 


_ tic. 


416 THE PHYSICAL GEOGRAPHY OF THE SEA. 


cnarter Object of such charts is to show the directions and relative 
salen frequency of gales in all parts of the sea; the relative 
frequency of cals, fogs, rain, thunder, and lightning. 

§955 These charts are very instructive. They show that 
wist that half of the atmospherical coating of the earth which 
carts covers the northern hemisphere—if we may take as a 
type of the whole what occurs on either side of the equa- 
tor in the Atlantic Ocean—is in a much less stable con- 

dition than that which covers the southern. 
§956 There are, as a rule, more rains, more gales of wind, 
vee more calms, more fogs, and more thunder and lightning, 


storms and 


camsin in the North than in the South Atlantic. These pheno- 


North and 
South At- mena, at equal distances from the equator north and 


ioe south, and for every 5° of latitude, have been compared ;' 
—that is, all the storms, calms, rains, &c., between the 
parallels of 25° and 30° north, for instance, have been 
compared with the same between the parallels of 25° and 
30° south ; those for January north being compared with 
those for January south, and so on for each month, be- 
tween all the five degree (5°, 10°, 15°, &c.) parallels from 

the equator to 60°, north and south. 
$957 In some places here and there, and in some months 
cP. now and then, there may be more gales, as in the neigh- 
tases: ~~ bourhood of Cape Horn, in the South than in the North 
Atlantic ; but such cases constitute the exceptions, they 
are by no means the rule. Cape Horn in the South 
Atlantic, and the Gulf Stream in the North, furnish seats 
for agents which are very marked in their workings. This 
Plate brings out the fact that, as a rule, rains and calms go 
together in the tropics; but beyond, rains and gales are 
more apt to occur at the same time, or to follow each other, 


1 Plate XIII. 


STORMS. A417 


With regard to the disturbing agents which are let loose 
from Cape Horn and the Gulf Stream upon the atmo- 
sphere, I beg leave to quote a remark of Jansen’s:— 
“In contemplating Nature in her universal aspect, in 
which all is so perfectly ordered that all the parts with 
mutual kindness support each other by the complaisant 
interposition of air and water, we cannot possibly reject 
the idea of unanimity of action; and we may conjecture 
that when, impeded or prevented by external local causes, 
their bond of union is broken, then are observed the 
terrible efforts of Nature, by which its almighty power 
is shown in combating that disturbance of which we know 
so little, and in renewing and perfecting those broken 
bonds. Forces which are otherwise working beyond the 
reach of human vision then come forth in the combat for 
the restoration of the disturbed equilibrium. They cause 
the earth to tremble to her centre, and man to stand 
anxious and dismayed. Yet Omniscience watches, a Pro- 
vidence cares, and the Almighty is love. The delightful 
land that is given us as a dwelling-place is, at the same 
time, the cause of all the disturbances in the air and in 
the ocean, whence the hurricanes and the ‘rivers in the 
sea” arise, which in turn are for the universal good ; 
where they are not found, we may be certain that the 
currents of the air and of the water work undisturbed, 
harmoniously together. And is not this the case in the 
south-east trade-wind of the South Atlantic Ocean ?” 


CHAPTER 
xVII. 


§ 958 


Jansen’s 
remarks 
on dis- 
turbing 
agents let 
loose upon 
the atmo- 
sphere. 


418 THE PHYSICAL GEOGRAPHY OF THE SEA. 


CHAPTER XVIIL 


ROUTES. 


How Passages have been Shortened, § 959.—How closely Vessels follow each 
other’s Track, 961.—The Archer and the Flying Cloud, 962. The great 
Race-course upon the Ocean, 964.—Description of a Ship-race, 966.—Present 
Knowledge of the Winds enables the Navigator to compute his Detour, 991. 


cuarter THE principal routes across the ocean are exhibited on 
XVIII. 


— Plate VIII; the great end and aim of all this labour and 


§ 959 - ona : 
the great YeSearch are in these, and consist in the shortening of 


aim and : c a S = p 4 
ent ofthe P2ssages—the improvement of navigation. Other in- 
aushor's terests and other objects are promoted thereby, but these 


labours 
last, in the mind of a practical people, who, by their 


and re- 
searches. 


habits of thought and modes of action, mark the age in 

which we live as eminently utilitarian, do not stand out 

in relief half so grand and imposing as do those achieve- 

ments by which the distant isles and marts of the sea 

have been lifted up, as it were, and brought closer toge- 

ther, for the convenience of commerce, by many days’ sail. 

$960 We have been told in the foregoing pages how the 
Adsan- winds blow and the currents flow in all parts of the 


knowidze ocean. These control the mariner in his course; and to 
and ewr- Know how to steer his ship on this or that voyage so as 
ae always to make the most of them, is the perfection of 
navigation. The figures representing the vessels are so 
marked as to show whether the prevailing direction of 

the wind be adverse or fair. 
$961 When one looks seaward from the shore, and sees a 
Popular ship disappear in the horizon, as she gains an offing on a 


error. 


voyage to India, or the Antipodes perhaps, the common 


ROUTES. 419 


idea is that she is bound over a trackless waste, and the 
chances of another ship, sailing with the same destination 
the next day, or the next week, coming up and speaking 
with her on the “pathless ocean,” would, to most minds, 
seem slender indeed. Yet the truth is, the winds and 
the currents are now becoming to be so well understood, 
that the navigator, like the backwoodsman in the wilder- 
ness, is enabled literally “to blaze his way” across the 
ocean ; not indeed upon trees, as in the wilderness, but 
upon the wings of the wind. The results of scientific 
inquiry have so taught him how to use these invisible 
couriers, that they, with the calm belts of the air, serve 
as sign-boards to indicate to him the turnings, and forks, 
and crossings by the way. 

Let a ship sail from New York to California, and the 
next week let a faster one follow after: they will cross 
each other’s path many times, and are almost sure to see 
each other by the way. Thus a case in point happens to 
be before me. It is the case of the Archer and the 
Flying Cloud on a recent voyage to California. They 
are both fine clipper ships, ably commanded. But it was 
not until the ninth day after the Archer had sailed 
from New York that the Flying Cloud put to sea, 
California-bound also. She was running against time, 
and so was the Archer, but without reference to each 
other. The Archer, with Wind and Current Charts in 
hand, went blazing her way across the calms of Cancer, 
and along the new route, down through the north-east 
trades to the equator; the Cloud followed after, cross- 
ing the equator upon the trail of Thomas of the Archer. 
Off Cape Horn she came up with him, spoke him, handed 
him the latest New York dates, and invited him to dine 


CHAPTER 
XVIII. 


Winds and 
currents 
are guides 
to the 
mariner. 


$ 962 


Case of twa 
vessels 
bound for 
California. 


Thev meet 
off Cape 
Horn. 


420 THE PHYSICAL GEOGRAPHY OF THE SEA. 


crapterR On board the Cloud; “which invitation,” says he of the 

a Archer, “I was reluctantly compelled to decline.” 

$963 The Flying Cloud finally ranged ahead, made her 
ie adieus, and disappeared among the clouds that lowered 
eee. upon the western horizon, being destined to reach her 

port a week or more in advance of her Cape Horn consort. 
Though sighting no land from the time of their separation 
until they gained the offing of San Francisco—some six 
or eight thousand miles off—the tracks of the two vessels 
were so nearly the same, that, being projected on Plate 
IX., they would appear almost as one. 

§964 This is the great race-course of the ocean; it is fifteen 
The great thousand miles in length. Some of the most glorious 
coun of : trials of speed and of prowess that the world ever 

witnessed, among ships that “walk the waters,” have 
taken place over it. Here the modern clipper ship—the 
noblest work that has ever come from the hands of man— 
has been sent, guided by the lights of science, to contend 
with the elements, to outstrip steam, and astonish the 
world. 

§965 The most celebrated and famous ship-race that has ever 
canvas, been run came off upon this course : it was in the autumn 
of 1862, of 1852, when navigators were beginning fully to reap 

the benefits of these researches with regard to the winds 
and currents, and other facts connected with the physical 
geography of the sea, that four splendid new clipper 
ships put to sea from New York, bound for California. 
They were ably commanded, and as they passed the bar 
at Sandy Hook, one by one, and at various intervals of 
time, they presented really a most magnificent spectacle. 
The names of these noble ships and their master were, 
—the Wild Pigeon, Captain Putnam; the John Gilpin, 


ROUTES. 421 


Captain Doane—alas! now no more; the Flying Fish, 
Captain Nickels; and the Trade Wind, Captain Webber. 
Like steeds that know their riders, they were handled 
with the most exquisite skill and judgment, and in such 
hands they bounded out upon the “glad waters” most 
eracefully. Each being put upon her mettle from the 
start, was driven, under the seaman’s whip and spur, at 
full speed over a course that it would take them three 
long months to run. 

The Wild Pigeon sailed October 12; the John 
Gilpin, October 29; the Flying Fish, November 1; 
and the Trade Wind, November 14. It was the season 
for the best passages. Each one was provided with the 
Wind and Current Charts ; each one had evidently 
studied them attentively ; and each one was resolved to 
make the most of them, and do his best. All ran against 
time; but the John Gilpin and the Flying Fish for 
the whole course, and the Wild Pigeon for part of it, 
ran neck and neck, the one against the other, and each 
against all. It was a sweepstake with these ships around 
Cape Horn, and through both hemispheres. 

Wild Pigeon led the other two out of New York, the 
one by seventeen, the other by twenty days. But luck 
and chances of the winds seem to have been against her 
from the start. As soon as she had taken her departure, 
she fell into a streak of baffling winds, and then into a 
gale, which she fought against and contended with for a 
week, making but little progress the while; she then had 
a time of it in crossing the horse latitudes. After having 
been nineteen days out, she had logged no less than 
thirteen of them as days of calms and baflling winds; 


CHAPTER 
XVIU. 


§ 966 
The vessela 
set sail. 


§ 967 
The start 
of the 
“Wild 
Pigeon.” 


422 THE PHYSICAL GEOGRAPHY OF THE SEA. 


enapter these had brought her no farther on her way than the 

ey parallel of 26° north in the Atlantic. Thence she had a 
fine run to the equator, crossing it between 33° and 34° 
west, the thirty-second day out. She was unavoidably 
forced to cross it so far west; for only two days before, 
she crossed 5° north in 30°—an excellent position. 

§968 In proof that the Pigeon had accomplished all that 
rau skill could do, and the chances against her would permit, 
Pollard. we have the testimony of the barque Hazard, Captain 

Pollard. This vessel, being bound to Rio at the same 
time, followed close after the Pigeon. The Hazard is an 
old hand with the charts; she had already made six 
voyages to Rio, with them for her guide. ‘This was the 
longest of the six, the mean of which was twenty-six 
and a half days. She crossed the line this time in 
34° 30’, also by compulsion, having crossed 5° north in 
31°. But, the fourth day after crossing the equator, she 
was clear of Cape St. Roque, while the Pigeon cleared it 
in three days.* 

$969 So far, therefore, chances had turned up against the 


Better for- 2 ° : me ae pee 
pte, Eigeon, in spite of the skill displayed by Putnam as a 


other ves- 


i navigator, for the Gilpin and the Fish came booming 


along, not under better management, indeed, but with a 
better run of luck and fairer courses before them. In 
this stretch they gained upon her—the Gilpin seven and 
the Fish ten days; so that now the abstract logs show 
the Pigeon to be but ten days ahead. 
§970 Evidently the Fish was most confident that she had 
Conrse the heels of her competitors; she felt her strength, and 


the of 
“Fish” was proud of it; she was most anxious for a quick run, 


* According to the received opinion, this was impossible. 


ROUTES. 423 


and eager withal for a trial. She dashed down south- cmapren 
wardly from Sandy Hook, looking occasionally at the a= 
charts; but feeling strong in her sweep of wing, and 
trusting confidently in the judgment of her master, she 
kept, on the average, two hundred miles to leeward of 
the right track. Rejoicing in her many noble and fine 
qualities, she crowded on her canvas to its utmost stretch, 
trusting quite as much to her heels as to the charts, and 
performed the extraordinary feat of crossing, the sixteenth 
day out from New York, the parallel of 5° north. 

The next day she was well south of 4° north, and in § 971 
the doldrums, longitude 34° west. 

Now her heels became paralyzed, for Fortune seems to Fortune 


seems to 


have deserted her a while,—-at least her master, as the ae 
winds failed him, feared so; they gave him his motive 
power; they were fickle, and he was helplessly battled 
by them. The bugbear of a north-west current off Cape 
St. Roque’ began to loom up in his imagination, and to 
look alarming ; then the dread of falling to leeward came 
upon him; chances and luck seemed to conspire against 
him, and the mere possibility of finding his fine ship 
back-strapped filled the mind of Nickels with evil fore- 
bodings, and shook his faith in his guide. He doubted 
the charts, and committed the mistake of the passage. 

The Sailing Directions had cautioned the navigator, § 972 
again and again, not to attempt to fan along to the east- is 
ward in the equatorial doldrums; for, by so doing, he greats 
would himself engage in a fruitless strife with bafiling 
airs, sometimes re-enforced in their weakness by westerly 
currents. But the winds had failed, and so too, the 
smart captain of the Flying Fish evidently thought, had 


1 § 470. 


CHAPTER 
XVIII, 


— 


Time lost. 


§ 973 
The cap- 
tain sees 
and ac- 
know- 
ledges his 
error. 


§ 974 


The “ Haz- 
ard.” 


4294 THE PHYSICAL GEOGRAPHY OF THE SEA. 


the Sailing Directions. They advise the navigator, in 
all such cases, to dash right across this calm streak, stand 
boldly on, take advantage of slants in the wind, and, 
by this device, make easting enough to clear the land. 
So, forgetting that the charts are founded on the expe- 
rience of great numbers who had gone before him, Nickels, 
being tempted, turned a deaf ear to the caution, and flung 
away three whole days, and more, of most precious time, 
dallying in the doldrums. 

He spent four days about the parallel of 3° north, 
and his ship left the doldrums, after this waste of time, 
nearly upon the same meridian at which she entered 
them. 

She was still in 34°, the current keeping her back just 
as fast as she could fan east. After so great a loss, her 
very clever master, doubting his own judgment, became 
sensible of his error, Leaving the spell-bound calms 
behind him, where he had undergone such trials, he wrote 
in his log as follows: “I now regret that, after making 
so fine a run to 5° north, I did not dash on, and work 
my way to windward to the northward of St. Roque, as 
I have experienced little or no westerly set since passing 
the equator, while three or four days have been lost in 
working to the eastward, between the latitude of 5° and 


90° 


3° north, against a strong westerly set ; 


2” 


and he might 
have added, “ with little or no wind.” 

In three days after this he was clear of St. Roque. 
Just five days before him, the Hazard had passed exactly 
in the same place, and gained two days on the Fish, by 
cutting straight across the doldrums, as the Sailing Direc- 
tions advised him to do. 


ROUTES. 425 


The Wild Pigeon, crossing the equator also in 33°, cnapres 
VIll. 
had passed along there ten days before, as did also the = 


Trade Wind twelve days after. The latter also crossed ple ame 


the line to the west of 34°, and in four days after had *'8°°"" 
cleared St. Roque. 

But, notwithstanding this loss of three days by the § 976 
Fish, who so regretted it, and who afterward so hand- eee 
somely retrieved it, she found herself, on the 24th of ore 
November, alongside of the Gilpin, her competitor. They pin.” 
were then both on the parallel of 5° south, the Gilpin 
being thirty-seven miles to the eastward, and of course in 
a better position, for the Fish had yet to take advantage 
of slants, and stand off shore to clear the land. They had 
not seen each other. 

The charts showed the Gilpin now to be in the best § 977 
position, and the subsequent events proved the charts Pritence 
to be right, for thence to 53° south the Gilpin gained charts. 
on the Pigeon two days, and the Pigeon on the Fish 
one. 

By dashing through the Straits of Le Maire, the Fish § 978 
gained three days on the Gilpin ; but here Fortune again Pater 


tune of the 
deserted the Pigeon, or rather the winds turned against “Wil 


her; for as she appeared upon the parallel of Cape Horn, etn 
and was about to double round, a westerly gale struck 
her “in the teeth,” and kept her at bay for ten days, 
making little or no way, except alternately fighting in a 
calm or buffeting with a gale, while her pursuers were 
coming up, “ hand over fist,” with fine winds and flowing 
sheets. 

They finally overtook her, bringing along with them § 979 
propitious gales, when all three swept past the Cape, and 


496 THE PHYSICAL GEOGRAPHY OF THE SEA. 


cHapter crossed the parallel of 51° south on the other side of the 
XVIII. 

4 “ Horn,” the Fish and the Pigeon one day each ahead of 

aoubie the Gilpin. 


Cape Horn 


The Pigeon was now, according to the charts, in the 
best position, the Gilpin next, and the Fish last; but all 
were doing well. 

§980 From this parallel to the south-east trades of the Pa- 
Prevailing cific, the prevailing winds are from the north-west. The 

position of the Fish, therefore, did not seem as good as 
the others, because she did not have the sea-room in case 
of an obstinate north-west gale. 

§981 But the winds favoured her. On the 30th of De- 
rosition f cember the three ships crossed the parallel of 35° south, 
on gor, the Fish recognising the Pigeon; the Pigeon saw only a 

“clipper ship,” for she could not conceive how the ship 
in sight could possibly be the Flying Fish, as that vessel 
was not to leave New York for some three weeks after 
she did: the Gilpin was only thirty or forty miles off at 
the same time. 

$982 The race was now wing and wing, and had become 
Excite. exciting. With fair winds and an open sea, the compe- 
therace. titors had now a clear stretch to the equator of two 

thousand five hundred miles before them. 

§983 The Flying Fish led the way, the Wild Pigeon pressing 
her hard, and both dropping the Gilpin quite rapidly, who 
was edging off to the westward. 

The two foremost reached the equator on the 13th of 
January, the Fish leading just twenty-five miles in lati- 

tude, and crossing in 112° 17’;* the Pigeon forty miles 


* Twenty-five days after that the Trade Wind clipper came along, crossed in 
112°, and had a passage of sixteen days thence into San Francisco, 


ROUTES. 427 


farther to the east. At this time the John Gilpin had onaprer 
dropped two hundred and sixty miles astern, and had see 
sagged off several degrees to the westward. 

Here Putnam, of the Pigeon, again displayed his tact § 984 
as a navigator, and again the fickle winds deceived him. ee of oe 
The belt of north-east trades had yet to be passed: it eee 
was winter: and, by crossing where she did, she would 
have an opportunity of making a fair wind of them, 
without being much to the west of her port when she 
should lose them. Moreover, it was exactly one year 
since she had passed this way before: she then crossed 
in 109°, and had a capital run thence of seventeen days 
to San Francisco, 

Why should she not cross here again? She saw that § 985 
the fourth edition of Saaling Directions, which she had Minck 
on board, did not discountenance it, and her own expe- “Pigeon 
rience approved it. Could she have imagined that, in 
consequence of this difference of forty miles in the crossing 
of the equator, and of the two hours’ time behind her 
competitor, she would fall into a streak of wind which 
would enable the Fish to lead her into port one whole 
week? Certainly it was nothing but what sailors call 
“a streak of ill luck” that could have made such a 
cifference. 

But by this time John Gilpin had got his mettle up again. § 986 
He crossed the line in 116°,—exactly two days after the Run of the 


John “ Gil- 


other two,—and made the glorious run of fifteen days pin” 


thence to the pilot grounds of San Francisco. 

Thus end the abstract logs of this exciting race and 
these remarkable passages :— 

The Flying Fish beat. She made the passage in 92 § 987 


CHAPTER 
XVIII. 
The “ Fly- 
ing Fish” 
wins the 

race. 


§ 988 


§ 989 


Result of 
the races 
shows the 
value of 
wind and 
current 
charts, and 
how well 
they are 
under- 
stood. 


§ 990 


§ 991 


Author's 
computa- 
tion borne 
out by 
facts. 


428 THE PHYSICAL GEOGRAPHY OF THE SEA, 


days and 4 hours from port to anchor; the Gilpin in 93 
days and 20 hours from port to pilot ;* the Wild Pigeon 
had, 118. The Trade Wind followed, with 102 days, 
having taken fire and burned for eight hours on the way. 

The result of this race may be taken as an illustration 
as to how well navigators are now brought to understand 
the winds and the currents of the sea. 

Here are three ships sailing on different days, bound 
over a trackless waste of ocean for some fifteen thousand 
miles or more, and depending alone on the fickle winds 
of heaven, as they are called, to waft them along; yet, 
like travellers on the land bound upon the same journey, 
they pass and repass, fall in with and recognise each 
other by the way; and what, perhaps, is still more 
remarkable, is the fact, that these ships should each, 
throughout that great distance, and under the wonderful 
vicissitudes of climates, winds, and currents, which they 
encountered, have been so skilfully navigated, that, in 
looking back at their management, now that what is past 
is before me, I do not find a single occasion, except the 
one already mentioned, on which they could have been 
better handled. 

There is another circumstance which is worthy of 
notice in this connection, as illustrative of the accuracy 
of the knowledge which these investigations afford con- 
cerning the force, set, and direction both of winds and 
currents, and it is this :— 

I had computed the detour which these vessels would 
have to make, on account of adverse winds, between 
New York and their place of crossing the equator. The 


* The abstract log of the Gilpin is silent after the pilot came on board. 


ROUTES. 4.99 


whole distance, including detour, to be sailed to reach 
this crossing at that season of the year, was, according to 
calculation, 4115 miles. The Gilpin and the Hazard 
only kept an account of the distance actually sailed,— 
the former reaching the equator after sailing 4099 miles, 
the latter 4077; thus accomplishing that part of the 
voyage by sailing, the one within thirty-eight, the other 
within sixteen miles of the detour which calculation 
showed they would be compelled to make on account of 
head-winds. With his way blazed through the forest, 
the most experienced backwoodsman would have to make 
a detour greater than this on account of floods in the 
rivers. Am I far wrong, therefore, when I say that the 
present state of our knowledge, with regard to the phy- 
sical geography of the sea, has enabled the navigator to 
blaze his way among the winds and currents of the sea, 
and so mark his path that others, using his signs as 
finger-boards, may follow in the same track ? 


CHAPTER 
XVIII. 


Result of 
our pre- 
sent know- 
ledge of 
physical 
geography 
of the sea 


430 THE PHYSICAL GEOGRAPHY OF THE SEA. 


CHAPTER XIX. 


BRUSSELS CONFERENCE, ETC, 


Brussels Conference, § 996.—How Navigators may obtain a Set of the Maury 
Charts, 997.—The Abstract Log, 998. 


cuarter ] HAVE, I am aware, not done more in this little book 
XIX. 


— than given only a table or two of contents from the 


§ 992 


Authors interesting volume which the physical geography of the 

rem’ sea is destined some day to open up to us. The subject 

work. is a comprehensive one: there is room for more labourers, 
and help is wanted. 

Nations, no less than individuals; “stay-at-home tra- 
vellers,” as well as those who “go down to the sea in 
ships,” are concerned in the successful prosecution of the 
labours we have in hand. 

We are now about to turn over a new leaf in naviga- 
tion, on which we may confidently expect to see recorded 
much information that will tend to lessen the dangers of 
the sea, and to shorten the passages of vessels trading up- 
on it. 

§ 993 We are about to open in the volume of Nature a new 
Anew chapter, under the head of Marine MereoroLocy. In 


chapter in 

thal it are written the laws that govern those agents which 

Nature “the winds and the sea obey.” In the true interpreta- 
tion of these laws, and the correct reading of this chapter, 
the planter as well as the merchant, the husbandman as 
well as the mariner, and states as well as individuals, are 


concerned. All have a deep interest in these laws; for 


BRUSSELS CONFERENCE. 431 


with the hygrometrical conditions of the atmosphere the cmaprer 
well-being of plants and animals is involved. The health we 
of the invalid is often dependent upon a dry or a damp 
atmosphere, a cold blast or a warm wind. 

The atmosphere pumps up our rivers from the sea, and § 994 
transports them through the clouds to their sources among Effect of 


the atmo- 


the hills; and upon the regularity with which this ma- sphere on 
chine, whose motions, parts, and offices, we now wish to Se 
study, lets down that moisture, and the seasonable supply 
of rain which it furnishes to each region of country, to 
every planter, and upon all cultivated fields, depend the 
fruitfulness of this country, the sterility of that. 

The principal maritime nations, therefore, have done § 995 


well by agreeing to unite upon one plan of observation, no uae 


time na- 

is : . Cae : tions have 

and to co-operate with their ships upon the high seas (0.1) 
with the view of finding out all that patient research, eee 


systematic, laborious investigation, may reveal to us 0fobseve 


concerning the winds and the waves; and philosophical 
travellers, and every sailor that has a ship under his foot, 
may do even better by joining in this system. 

By the recommendations of the Brussels Conference, $ 996 
every one who uses the sea is commanded or invited to Recom- 


mendation 


make certain observations; or, in other words, to pro- aes 
Ss: 


pound certain queries to Nature, and to give us a faithful Cont 


statement of the replies she may make. 


Instru- 
ments. 


Now, unless we have accurate instruments, instruments 
that will themselves tell the truth, it is evident that we 
cannot get at the real meaning of the answers that 
Nature may give us. 

An incorrect observation is not only useless of itself, 
but, when it passes undetected among others that are 


432 THE PHYSICAL GEOGRAPHY OF THE SEA, 


cuapteR correct, it becomes worse than useless; nay, it is mis- 
=  chievous there, for it vitiates results that are accurate, 
places before us wrong premises, and thus renders the good 

of no value. 
§997 Those ship-masters who, entering this field as fellow- 
Ship-  Jabourers, will co-operate in the mode and manner recom- 


masters 


whoo. mended by the Brussels Conference, and keep, voyage 
operate 


ee fo after voyage, and as long as required, a journal of observa- 
saline tions and results according to a prescribed form—and 
which form is annexed, under the title of Abstract Log— 

are entitled, by sending the same, at the end of the voy- 

age, to the Superintendent of the National Observatory, 

to a copy of my Sailing Directions, and such sheets of the 

charts as relate to the cruising-ground of the co-operator. 

§ 998 There are two forms of abstract logs: one, the more 
roe’ elaborate, for men-of-war; the other for merchantmen. 
loge The observations called for by the latter are a minimum, 
the least which will entitle the co-operator to claim the 
proffered bounty. It must give, at least, the latitude 

and longitude of the ship daily; the height of the 
barometer, and the readings of both the air and the water 
thermometer, at least once a day; the direction and force 

of the wind three times a-day—first, middle, and latter — 
part—at the hours eight p.m, four AM., and noon; the 
variation of the compass occasionally ; and the set of the 

Ovserva- Current whenever encountered. These observations, to 


tions must 

heaceue be worth having, must be accurately made ; and as every 
thermometer and every barometer has its sources of error, 
consequently every ship-master who undertakes hereafter 
to co-operate with us, and keep an abstract log, should 


have his barometer and thermometer accurately compared 


THE ABSTRACT LOG. 433 


with standard instruments, the errors of which have been 
accurately determined. 

These errors the master should enter in the log. The 
instruments should be numbered, and he should so keep 
the log as to show what instrument is in use. For in- 
stance, a master goes to sea with thermometers Nos. 4719, 
1, 12, &c., their errors having been ascertained and en- 
tered on the blank page for the purpose in the abstract log. 
He first uses No. 12. Let it be so stated in the column 
of remarks, when the first observation is recorded, thus: 
Thermometer No. 12. During the voyage, No. 12 gets 
broken, or for some reason is laid aside, and another, say 
4719, is brought into use. So state when the first observa- 
tion with it is recorded, and quote in the column of remarks 
the errors both of No. 12 and 4719. Now with such a 
statement of errors given in the log for each of the instru- 
ments, according to the number, the observations may be 
properly corrected when they come up here for discussion. 

It is rare to find a barometer or a thermometer that 
has no error, as it is to find a chronometer without error. 
A good thermometer, the error of which the maker should 
guarantee not to exceed in any part of the scale one 
degree, will cost, in the United States, not less than two 
dollars, perhaps two and a half dollars. 

The errors of thermometers sometimes are owing to in- 
equalities in the bore of the tube, sometimes to errors of 
division on the scale, &c, Therefore, in comparing ther- 
mometers with a standard, they should be compared, at 
least, for every degree between melting ice and blood heat. 


28 


CHAPTER 
XIX. 


§.999 


How the 
abstract 
log ought 
to be kept 


§ 1000 


Instru- 
ments 
rarely 
without 
error. 


§ 1001 


How thers 
mometers 
ought to 
be com- 
pared. 


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TRADE-WINDS OF THE SOUTHERN HEMISPHERE. 409 


CHAPTER XX. 


FORCE OF THE TRADE-WINDS OF THE SOUTHERN HEMISPHERE, 
—PECULIARITIES IN ITS ATMOSPHERIC CIRCULATION. 


The spirit in which the Researches touching the Physics of the Sea have been 
conducted, § 1002.—Reasons for supposing Crossings of the Air in the Calm 
Belts, 1003.—The “‘ Brave West Winds” of the Southern Hemisphere; their 
Strength and Regularity, 1004. —Counter-trades, 1005.—Measuring the Strength 
of the Trade-winds, 1006.—The S.E. stronger than the N.E. Trade-winds, 
1007.—Waves, 1008.—New Facts in Meteorology, 1009. —Calms and Gales on 
opposite Sides of the Equator compared, 1010.—The Propelling Power of 
the Winds of the Southern Hemisphere; whence derived, 1011.— Why do the 
Counter-trades blow toward the Poles? 1012.—Precipitation between the 
Parallels of 55° and 60° N. and S. compared, 1013.—A heavy Rain-fall, 1014. 
—-The Counter-trades of the Southern Hemisphere vapour-bearing Winds, 1015. 
—The latent Heat of Vapour, 1016.—Its Amount, 1017.—Icebergs, their 
Offices, &e., 1018.—The Physical Features of the Antarctic Continent, 1019.— 
Precipitation the Cause of the Low Barometer in High Southern Latitudes, 
1020.—A Perpetual Cyclone, 1021.—Conclusion, 1022.—Dr. Jilek’s Descrip- 
tion of the Antarctic Regions, 1023. 


WHENEVER, in the course of my investigations touching 
the physics of sea and air, new facts have been elicited, I 
have, if they appeared consistent enough to be suggestive, 
never hesitated to follow them up with suggestions, espe- 
cially if hypothesis seemed to be called for. The prin- 
ciple by which I have sought to be governed is this: 
fairly to weigh the facts under discussion, and then to offer 
in explanation that hypothesis which would apparently 
best reconcile them. In case I could not reconcile all by 
any one supposition, the preference has been given to that 
hypothesis which would reconcile the greatest number. 
Then, as additional facts were developed, the hypothesis 
was, if necessary, discarded or amended, as the new lights 
seemed to require. 


CHAPTER 
xx. 
$ 1002 
Hypothe- 
sis ought 
to be 
founded 
on facts. 


CHAPTER 


Spirit in 
which in- 
vestiga- 
tion 
should be 
couducted. 


Crossings 
of air at 
the calm 
belts 


456 THE PHYSICAL GEOGRAPHY OF THE SEA. 


As an investigator in the particular field to which 
much of my labour is directed, I do not consider that 1 
should content myself by merely stating observations and 
facts. It is the business of the investigator to let those 
who labour with him have the benefit of his thoughts 
and conclusions as well as a fair statement of his facts. 
Such thoughts, though they be founded in misapprehen- 
sion, rarely fail to help the cause of progress and of truth; 
for, though wrong in themselves, they impart interest to 
the subject, set others to thinking, and often suggest 
what is right. Moreover, by such a course discussion is 
encouraged; and scientific discussion, when philosophically 
directed and properly conducted, is always profitable. 

It was in this spirit that this work has, from its com- 
mencement, been conducted, and it was in this spirit that, 
in treating of the general circulation of the atmosphere, 
the crossings at the calm belts (chap. vi.), were suggested. 
Take, as an illustration of this crossing, the calm belt of 
Capricorn, Near this tropic there is a band encircling 
the earth, from which the wind on one side is perpetually 
blowing toward the Equator, and on the other almost as 
perpetually blowing toward the Pole. These winds are 
on the surface; and to supply air for such winds there 


must be a regular influx—a pouring in—at the top of 
this calm belt. As the surface currents carry away this 
air both toward the north and the south, it must return 
by counter currents both from the north and the south to 
keep up the supply. These counter currents are admit- 
ted to be upper currents. The same in-pouring and out- 
flowing take place at the calm belt of the Equator and 
the calm belt of Cancer, only at the Equator the in-pour 


ing currents are at the surface of the earth, while at the 


TRADE-WINDS OF THE SOUTHERN HEMISPHERE, 457 


two tropical calm belts they are in the regions of the cuarres 
. xX. 
upper air. 


In consequence of diurnal rotation these currents, as ritect of 


diurnal 


they come from toward the Pole and approach the Equa- rotation 


on the 
tor, whether as upper or as surface currents, have much gj cur- 


easting in them ; and, in like manner, they acquire west- ""* 
ing as they return toward the Poles. 

Arrived with my investigations at this stage in the 
construction of a theory, a question of this sort arose: 
Does the air which is poured into these calm belts from 
the north, for instance, return to the north as it flows 
out, or does it keep on its circuit toward the south ? 

There seemed to be reasons for supposing that the air reasons 


G for st 
which enters the calm belts from the north flows out Sain 


crossings 
of the air 
in the 
calm belts. 


toward the south,’ and vice versa ; consequently, it was 
held that the construction of the atmospherical machinery 
is such as to require a crossing of air in those calm belts. 
The circumstances and considerations which seemed to § 1003 
be in favour of this conjecture are there stated in detail, 
but briefly they are these :— 
Ist. Opposite seasons in the hemispheres : The identity 1st, oppo- 


. ‘ . site sea- 
of atmospherical constituents in all parts of the earth, sonsinthe 


hemi- 


notwithstanding the unequal distribution over its surface, gheres 
L 


both as to place, numbers, and kind, of the agents which 
corrupt and of those which purify the air. This identity 
of constituents seemed to favour the idea of a general and 
regular intermingling ; nay, the principles of adjustment 
which obtain in that exquisite system of compensations 
which is displayed in the workings of the physical 
machinery of our planet, seem to call for such regular and 


1 See chapter vi. 


2d. Aque- 
ous area 
of south- 
ern hemi- 
sphere 
greater 
than that 
of north- 
ern. 


3d. The 
sea Water 
of the 
southern 
hemi- 
sphere 
heavier 
than that 
of the 
northern. 


438 THE PHYSICAL GEOGRAPHY OF THE SEA. 


active intermingling of the fluid covering, both aerial and 
aqueous, of the earth as would keep each element pure 
and make it homogeneous. Were it not so, we know of 
physical agents which, in process of time, would make 
both the air and the water of the two hemispheres quite 
different those of the one from those of the other. Con- 
sequently, if the atmosphere of one hemisphere were to 
become different from that of the other, the air of the 
north would not be suited to the flora or the fauna of the 
southern hemisphere, and conversely. 

2d. The aqueous area of the southern hemisphere is 
much greater than that of the northern, Pat, notwith- 
standing the evaporating surface of the former so much 
exceeds that of the latter, the amount of precipitation 
upon the land is very much greater in the one that ex- 
poses the smallest sea surface or source of vapour. 

This circumstance had induced meteorologists, in treat- 
ing of the exquisite workmanship displayed in the atmos- 
pherical machinery that surrounds our planet, to liken 
the southern hemisphere to the boiler, the northern to the 
condenser of the steam-engine. How, then, without a 
crossing of the winds at the calm places, could the vapour 
be transported from one side of the Equator to the other ? 

3d. Another link in this chain of circumstantial evi- 
dence suggesting a crossing, is in the fact that the sea 
water of the southern hemisphere is, parallel for parallel, 
specifically heavier than sea-water of the northern hemi- 
sphere. 

As a rule, parallel for parallel, the former is the cooler, 
but at the same temperature it is specifically heavier, and, 
therefore, salter. That the waters of trans-equatorial 
seas are salter had been pointed out by Daubeney, 


TRADE-WINDS OF THE SOU'IHFRN HEMISPHERE. 439 


Dove, ef al. But, with a view of determining by actual 
measurement a value for the difference of saltness, I pro- 
cured from Captain. John Rodgers, of the North Pacific 
Surveying Expedition,a series of hydrometricaland thermal 
observations, for every degree of latitude, on a voyage in 
the United States ship “ Vincennes,” from 71° north down 
through Behring’s Strait, around Cape Horn in 57° south, 
and thence through the Atlantic Ocean up to New York. 
These observations show that the mean specific gravity 
of sea-water is about .0007 greater in the southern than 
in the northern hemisphere. 
he hypothesis which requires a crossing of the winds 
at the calm belts is consistent with this fact. Half the 
quantity of fresh water that it would take to dilute the 
brine of southern oceans so as to reduce the specific 
gravity of their waters to the average of cis-equatorial 
seas, suggests the amount of fresh water which the winds 
of the southern hemisphere take up as vapour, carry away, 
and do not rain down again on that side of the Equator. 
The water which is thus transported in clouds and rained 
upon northern fields has to find its way back to the seas 
of the south through the currents of the ocean. Hence 
the difference in saltness suggests the amount of fresh 
water which is perpetually in transitu between the two 
hemispheres, as vapour through the clouds from the 
southern, and as rain through the drainage of the land 
and currents of the sea from the northern. This half 
difference would, to be exact, require a further correction 
on account of the inequality in the distribution of land 
and water in the two hemispheres. 
The vapour which gives excess of precipitation to the 
northern hemisphere is supplied from the southern, and 


CHAPTER 
XxX. 


Difference 
of saltness 
in sea 
water de- 
termined 
by mea- 
surement, 


Mean spe- 
Cifie gra- 
vity of sea 
water. 


Amount of 
fresh 
water car- 
ried north- 
ward by 
the winds 


CHAPTER 
XX. 


Agents 
which 
guide 
these 
crossings 
unknown. 


4th. Eh- 
renberg’s 
discover- 
ies with 
the micro- 
scope. 


440 THE PHYSICAL GEOGRAPHY OF THE SEA. 


it can be conveyed through no other channel but the air, 
nor brought by any other carriers but the winds. If any 
portion of the air which the south-east trades pour into 
the belt of the equatorial calms passes, after rising up, 
over into the northern hemisphere, it is axiomatic that a 
portion of like volume of that which the north-east trades 
pour into the same belt should pass over into the south- 
ern hemisphere. What may be the kind or the character 
of the agents to guide these crossings, and lead the air 
from one hemisphere to the other, it may not be easy to 
discover; it may be magnetism; it may be electricity 
that is concerned in it; but because we cannot detect 
them that is no proof of their non-existence. IPf there be 
a crossing, there is a power to guide the air through its 
mazes ; for, rely upon it, the wind in its circuit is left no 
more to chance than is the earth in its orbit. There are 
forces to restrain each and to keep it within its limits. 

4th. Ehrenberg’s discoveries with the microscope: In 
the sea-dust and red fogs of the North Atlantic he recog- 
nises organisms from South America. This dust has been 
collected for his microscope on the polar side of the north- 
east trades, and the inference is, that it was conveyed 
first to the equatorial calm belt by the surface wind, and 
was carried thence to the calms of Cancer by the upper 
currents. 

Thus this hypothesis concerning the crossing at the 
calm belts, and the flowing of the air over from one hemi- 
sphere to the other, seems to be consistent with all the 
facts and circumstances mentioned in 1, 2, 3, and 4. 

So far, however, the evidence seemed more specific touch- 
ing the crossings at the equatorial calm belt than at the 
tropical. The vapour that is brought over into the northern 


TRADE-WINDS OF THE SOUTHERN HEMISPHERE, 441 


hemisphere is probably taken up by the south-east trade- cuaprea 


. . Bye0 : XX. 
winds. This supposition and Ehrenberg’s “tallies” to the ** 
wind, as his sea-dust has been called, suggests the idea of a pier 


crossing at the calms of Cancer. But the circumstances /8hes” 
going to show the crossing at the calms of Capricorn did "+ 
not amount to evidence ; the crossing was only inference 
drawn by analogy. 

My own observations, and the experience of mariners § 1004 
who are acting as observers in these researches touching 
sea and air, show that the westerly winds which blow 
counter to the trades on the polar side of the tropical 
calms are much more steady, strong, and constant in the 
southern than in the northern hemisphere. 

The former have won for themselves, among mariners, the 
the name of the “brave west winds” of the extra-tropical Benes 

winds” 


south, They are quite as constant from the west as in ofthe 
the North Atlantic the trades are from the east. Sailing 


southern 
hemi- 


with them to and from Australia, ships under canvas ?"° 


alone have attained a speed and accomplished runs which 
steam has never enabled any vessel to reach. In two 
months’ time and less, sailing vessels have performed 
voyages of complete circumnavigation before these brave 
winds. 

Since, then, these winds are so much more constant and stronger 


and more 


brave than those of corresponding latitudes in our hemi- constant 


than those 


sphere, how is it with the south-east trades as compared of tie 

for strength with the north-east trades ? =a 
For convenience of description we will hereafter § 1005 

allude to the “brave west winds,” or rather to the 

westerly winds which prevail on the polar side of Cancer 

and Capricorn in both hemispheres, as the “ counter- 


trades,” 


CHAPTER 
XX. 


Compari- 
son be- 
tween the 
counter- 
trades of 
the two 
hemi- 
spheres. 


§ 1006 


4} 


>) 


_ 


THE PHYSICAL GEOGRAPHY CF THE SEA. 


Since the counter-trades of the southern are stronger 


and steadier than the counter-trades of the northern hemi- 


sphere, we should establish another link in the chain of 


circumstances tending to show the calm belt crossings of 


the wind, if it should turn out that the south-east trades 


are also fresher than the north-east. - 


To settle this question, the knots run per hour by 


299 


2235 vessels through the south-east trades of the Indian 


Ocean, and through both systems of the Atlantic, were 


compared. 


The average speed of ships propelled by these 


winds is expressed in the following tabular statement. 


The comparison is confined to the rate of sailing between 
the parallels of 10° and 25°, because this is the belt of 


steadiest 


trades. 


Average Average Speed through the Trade-winds of the North Atlantic and 
South Indian Ocean. 


speed of 
the trade-= 
wiids. 


Jannuary, 
February, 
March, ... 
| Apri, 

| May, 
June, 
July, 
August, ... 
September, 
October, ... 
November, 
December, 


Means, 


KNOTS PER HOUR, FROM 


10° to 15°|15° to 20° 
Zils £lZ sla s 
18 | 63/72) 7. | 6 
Rei 6 (65005 
PS WET OWE A it by 
ON tek 3} D8) Ee 
| St, 8 | 6% 1 74 | 63 
Ore 8. Fae BE 
| 53]8 |8 | 8} | 64 
4317316 | 8} | 43 
53 | 84,6 |8 | 4 
74! 8} | 63/8 | 6 
hGciese iO afr, wae 
6 | 63 | 63 | 6% j 53 
fel Waleed al ve lod 


aed 


hee 


bees 


DD? OVO DB HTN OS II 


wa 
2 
c 
a 


20° to 25°! AVERAGE. 


S.E. 


rades. 


i, 


te 


Pin bho 


Dd SITS AT SI AT ST DO ODD 
Die BIC BIRO 


=| 


COURSE STEERED 


THROUGH. 

N.E. S.E. 
Trades, Trades. 
N. 49° W.|S. 69° W. 

N.46 W. do. 
N. 47 | do. 
N. 48 W.fS. 70° W. 
N. 46 W.) do. 
N. 43 W.| do. 
IN. 46 W. do. 
N.40 W.|S. 69° W. 
N. 50° W.! do. 
N.45 W.! do. 
N.49 W./ do. 
N.48 W,| do. 
N 


_ 47° W.'8.694 °W. 


Average course steered through the N.E, Trades, N.W. } W. 
S.E. Trades, W.S.W. 


” ” 


” 


TRADE-WINDS OF THE SOUTHERN HEMISPHERE. 443 


Average Speed through the Trade-winds of the North and South 
Atlantic Oceans. 


KNOTS PER HOUR, FROM 


15° to 10°) averaGeE. COURSE STEERED 
a | . - THROUGH, 


Sis 
= 


= ; S.E. N.E. 
Trades. Trades, 


Trades 


i | 


[Sd 


January, 
February, 
March, ... 
|} April, 
May, 
June, 
July, 
August, ... 
September, ... 
October, ... 
November, 
December, 


ore 1 
tipo os 
PENI 

=p 
thee 


RAK Lot tol te 


Piece 


ad 


ERB KE DESI ISI 
Pe 


bh 


Cain 


DOD OVD D HD HD GN On Od 
tren 


Old ed 


DOr & Oy D OID MD DD 
Pe dt bet dt tt et 


Ot D3 Od D3 G1 TD GS} Or Ot O32 On Or 
ston 
ele we eo Bod 


DOH C1 D NID DD MD Dn 
D2 D2 QUAI D2 DMT D3 DDD Oy 


+ 
To Oe ONT AI AT AT AT 
toe 


PRO b A DKS 


6 
+ 
| 6 
eo 
ly 
5 
5 
5 
5 
5 
6 
5 


LOHR te 
Sh 


A) AnnnnnnnnmnA 
: , 


fon) 
for] 
a 
te 


Means, 


Average course steered through the S.E. Trades, N.W. by W. 
N.E. Trades, 8.8. E. 


” a) a? 


It is well to observe, that on each of these three oceans, 
though the direction of the wind is the same, the course 
steered by each fleet is different; consequently, these 
unemometers are at different angles with the wind; 
through the south-east trades the wind is nearly aft in 
the Atlantic, and quartering in the Indian Ocean ; giving 
an average sailing speed of 7 knots an hour in the 
former, and of 6 in the latter; while through the north- 
east trades the average speed is 64 knots an hour one 
way (N.W. 2 W..)s with the wind just abaft the beam, 
and 5% the other (S.S.E.), with the wind at a point not 
so favourable for speed. Indeed, most of the ships which 
average a 8.S.E. course through this part of the north- 
east trade-wind belt are close hauled; therefore the 


CHAPTER 
xX. 


Effect of 
the differ- 
ent course 
steered by 
the fleets 
on the 
measur2- 
ment of 
speed. 


CHAPTER 
xx. 


— 


Correct 
method 

of measur- 
ing the 
compara- 
tive 
strength 
of wind 


§ 1007. 


Mean 
speed ofa 
ship sail- 
ing with 
average 
trades. 


South-east 
trades 
stronger 
than the 
Oils east. 


A444 THE PHYSICAL GEOGRAPHY OF THE SEA. 


average strength of the trades here cannot be fairly com- 
pared with the average strength where the fleet have free 
winds. What is the difference in the strength of such winds, 
which, impinging upon the sails, each at the particular 
angle indicated above, imparts the aforesaid velocities ? 
Moderate winds, such as these are, give a ship her highest 
speed generally when they are just abaft the beam, as 
they are for a north-west course through the north-east 
trades. So, to treat these ships as anemometers that will 
really enable us to measure the comparative strength of 
the winds, we should reduce the average knots per hour 
to the average speed of a mean ship sailing through 
average “trades” in each ocean, with the wind imping- 
ing upon her sails at the same angle for all three, as, for 
example, just abaft the beam, as in the North Atlantic. 
Let us apply to the average speed through the South 
Atlantic and Indian Ocean such a correction. Through 
the former the wind is aft; through the latter quarter- 
ing. If we allow two knots for the one, and one for the 
other, we shall not be greatly out. Applying this correc- 
tion, we may state the speed of a mean ship sailing with 
average trades just abaft the beam to be as follows :-— 
Through the N.E. of the Atlantic, et pS 6} knots per hour. 


Through the S.K. of the Atlantic, Me Ke 8 
Through the 8.E. of the Indian Ocean, ae 8 


” ”? 


”) ”? 


I do not take into this comparison the force of the 
north-east trades on a south-south-east course (p. 442), 
because the winds along this route are known not to be 
as steady as they are further away from the African coast. 
Thus it is clearly established that the south-east trades are 
stronger than the north-east, and so they should be, if 
there be a crossing of winds in the calm belt of Capricorn. 


TRADE-WLNDS OF THE SOUTHERN HEMISPHERE, 445 


The counter-trades of the southern hemisphere move, 
as before stated, toward their pole more steadily and 
briskly than do the counter-trades of the northern hemi- 
sphere. ‘To give an idea of the difference of the strength 
of these two winds, I cite the fact that vessels sailing 
through the latter, as from New York to England, average 
150 miles a-day. Along the corresponding latitudes 
through the former, as on a voyage to Australia, the 
average speed is upward of 200 miles a-day. Conse- 
quently, the counter-trades of the southern hemisphere 
transport in given times larger volumes of air toward the 
south than our counter-trades do toward the north. This 
air returns to the tropical calm belts as an upper current. 
If, descending there, it feeds the trade-winds, then, the 
supply being more abundant for the south-east trades 
than for the north-east, the south-east trades must be the 
stronger ; and so they are; observations prove them so 
to be. 

Thus, the crossing of the air at the calm belts, though 
it may not be proved, yet it is shown to be so very pro- 
bable that the onus of proof is shifted. It now rests with 
those who dispute the crossing to prove their theory the 
true one. 

Arrived at this point, another view in the field of con- 
jecture is presented, which it is proper we should pause 
to consider, 

The movements of the atmosphere on the polar side 
of 40° north are, let it be repeated, by no means so 
constant from the west, nor is the strength of the wes- 
terly winds there nearly so great on the average as it is 
in the extra-tropical regions of the south. This fact is 
well known among mariners. Every one who has sailed 


CHAPTER 
xX. 


——. 


Difference 
of strength 
of the 
counter- 
trades of 
the south 
and north, 


The cross- 
ing of the 
air at the 
calm belts 
if not 
proved is 
yet pro- 
bable. 


$ 1008. 


Move- 
ments 
of the at- 
mosphere 
on the 
polar side 
of 40° 
north 


GHAPTER 
XX. 


Mountain 
billows 
raised by 
the “brave 
west 
winds.” 


Cause of 
the rapid 
runs of 
Australian 
elipper- 
ships. 


446 THE PHYSICAL GEOGRAPHY OF THE SKA. 


in that southern girdle of waters which belt the earth, 
on the polar side of 40°, has been struck with the force 
and trade-like regularity of the westerly winds which 
prevail there. The waves driven before these winds 
assume in their regularity of form, in the magnitude of 
their proportions, and in the stateliness of their march, an 
aspect of majestic grandeur that the billows of the sea 
never attain elsewhere. 

No such waves are found in the trade-winds, for, 
though the south-east trades are quite as constant, yet 
they have not the force to pile the water in such heaps, 
nor to arrange the waves so orderly, nor to drive them 
so rapidly as those “ brave” winds do. There the billows, 
following each other with measured tread, look, with 
their rounded crests and deep hollows, more like moun- 
tains rolling over a plain than the waves which we are 
accustomed to see, 

Many days of constant blowing over a wide expanse 
of ocean are required to get up such waves. It is these 
winds and waves which, on the voyage to and from_ 
Australia, have enabled the modern clipper-ship to attain 
a speed, and, day after day, to accomplish runs which at 
first were considered, even by the nautical world, as 
fabulous, and are yet regarded by all with wonder and 
admiration. 

Seeing, therefore, that we can bring in such a variety 
of facts and circumstances, all tending to show that the 
south-east trade-winds are stronger than the north-east, 
and that the westerly winds which prevail on the polar 
side of 40° south, are stronger and more constant than 
their antcecian fellows of the north, we may consider it 
as an established fact that the general system of atmo- 


TRADE-WINDS OF THE SOUTHERN HEMISPHERES. 447 


spherical circulation is more active in the southern than it 
is in the northern hemisphere. And, seeing that it blows 
with more strength and regularity from the west in the 
extra-tropical regions of the southern than it does in the 
extra-tropical regions of the northern hemisphere, we 
should deduce, by way of corollary, that the counter- 


trades of the south are not so easily arrested in their 


CHAPTER 
XX. 


Tie ge- 
neral sys- 
tem of ut- 
mospheri- 
cal circu- 
lation is 
more 
active in 
the south 
ern than 


course, or turned back in their circuits, as are those of im the 


the north. Consequently, moreover, we should not, 
either in the trades or the counter-trades of the southern 
hemisphere, look for as many calms as in those of the 
northern systems. 

Therefore, holding to this coroliary, we may con- 
sider the following as established facts in meteoro- 
logy :— 

That the south-east trade-winds are stronger than the 
north-east ; that the north-west passage-winds — the 
counter-trades of the south—are stronger and less hable 
to interruption in their circuits than the south-west, the 
counter-trades of the north; that the atmospherical cir- 
culation is more regular and brisk in the southern than 
it is in the northern hemisphere; and, to repeat, since 
the wind moves in its circuits more briskly through the 
southern than it does through the northern hemisphere, 
it consequently has less time to tarry or dally by the way 
in the south than in the north; hence the corollary just 
stated. But observations also, as well as mathematically 
drawn inferences, show that calms are much less preva- 
lent in the southern hemisphere. For this observations 
are ample; they are grouped together by thousands and 
tens of thousands, both on the Pilot and the Storm 
and Rain Charts. These charts have not been completed 


northern 
hemi- 
sphere. 


§ 1009 


New facts 
in meteor: 


ology. 


4438 THE PHYSICAL GEOGRAPHY OF THE SEA. 


cuarter for all parts of the ocean, but as far as they have been 

=“ constructed, the facts they utter are in perfect agreement 
with the terms of this corollary. 

$1010 These premises being admitted, we may ascend another 


Inference : : 
Fe round on this ladder, and argue that, since the atmo- 


drawn . . 
from the Sphere moves more briskly and in more constant streams 


preeeté through its general channels of circulation in the south- 
ern than it does through them in the northern hemi- 
sphere; and that, since it is not arrested in its courses by 
calms as often in the former as it is in the latter, neither 
should it be turned back by the way, so as to blow in 
gales from the direction opposite to that in which the 
general circulation carries it. 

The atmosphere, in its movements along its regular 
channels of circulation, may be likened, that in the 
southern hemisphere to a fast railway train; that of the 
northern to a slow. The slow train may, when “steam 
is up,’ run as fast as the fast train, but it is not obliged 
to get through so quick; therefore, it may dally by the 
way, stop, run back, and still be through in time. Not 
so the fast; it has not time to stop often or to run back 
far; neither have the counter-trades of the south time to 
blow backward; consequently, such being the conditiuns, 
we should also expect to find in the extra-tropical south 
a gale with easting in it much more seldom than in the 
extra-tropical north. 

We shall appeal to observations for the correctness of 
this conjecture, and claim for it, also, as presently will 
appear, the dignity of an established truth, 


TRADE-WINDS OF THE SOUTHERN HEMISPHERE. 449 


CHAPTER 
Average Number of Gales to the 1000 Observations, with Easting xx. 
and with Westing in them, between corresponding Parallels i sverage 
the North and South Atlantic, as shown by the Storm and Rain number of 


gales in 
Charts. the North 
North. | South. and South 
¢ Number of observations... ... «. 17,274 | 8756 Ailantic. 

Between 40° and 45° ~ Gales in 1000, with easting... ... 23 12 
u y westing... ... 66 82 
( Number of observations... ... «+. 11,425] 5548 
Between 45° and 50° ~ Gales in 1000, with easting... .. 24 1 
( i D westing... ... 106 61 
Number of observations... ... - .. 4816] 5169 
Between 50° and 55° | ates in 1000, with easting ... ... 24 10 
" M Westing ... see 144 97 


Thus the Storm and Rain Charts show that between 
the parallels of 40° and 55° there were in the northern 
hemisphere 33,515 observations, and that for every 1000 
observations there were 24 gales with easting, and 105 
with westing. In the southern there were 19,473 ob- 
servations, and for every 1000 of these there were 5 
gales with easting, and 80 with westing in them. 

Those for the southern hemisphere are only for that part spher» of 
of the ocean through which vessels pass on their way to and Genin the 
fro around Cape Horn. That part of this route which lies foe 
between 40° and 55° south, is under the lee of South °””* 
America; and Patagonia, that lies east of the Andes, is 
almost a rainless region; consequently, we might expect 
to find more unsteady winds and fewer rains in that part 
of the ocean where the observations for the southern part 
of the tables were made than we should expect to meet 
with well out to sea, as at the distance of two or three 
thousand miles to the eastward of Patagonia. So that 
the contrast presented by the above statement would 
probably be much greater did our observations extend 
entirely across the South, as they do across the North, 


Atlantic. But, as it is, the contrast is very striking. In 
29 


450 THE PHYSICAL GEOGRAPHY OF THE SRA. 


cuarrer some aspects, the meteorological agents of the two hemi- 
xx. 


—-s 


spheres, especially those forces which control the winds 
and the weather, differ very much. The difference is so 
wide as to suggest greater regularity and rapidity of cir- 
culation on one side of the Equator than on the other. 


Averace Average Number of Calms to the 1000 Observations, between the 

taine Parallels of 30° and 55°, in the North and South Atlantic, and 
between the Parallels of 30° and 60° in the North and South 
Pacific Oceans, as shown by the Pilot Charts, 


calms. 


ATLANTIC. 


North. South. | North. South. 


PACIFIC. 
BETWEEN THE PARALLELS OF 


30° and 35°, No. of observations... ... ---| 12,935 | 15,842 | 22,730 | 44,886 
Galms'to the LO00}do: © ccc) sxc, se 20 46 26 34 35 
35° and 40°, No. of observations... ... .-.| 22,136 | 23,439 | 18,939 | 66,275 
Calmstoithe LOO0O(GOs) sss) ccac cacuhene 37 24 31 23 
40° and 55°, No. of observations... ... ... 16,363 | 8,203 | 12,400 | 31,889 
Galmsito the 1000 GOs. s-; fan ccop cee 45 2 53 23 
45° and 50°, No. of observations... ... ...| 8,097 4,183 | 15,897 | 4,940 
Calms to the 1000 do. a... 2s aus one 38 25 35 21 
50° and 55°, No. of observations... ... ...! 3,519 3,660 | 382,804 | 9,728 
Calms to the 1000 do. ak eee wee ne 40 16 32) gi 
55° and 60°, No. of observations... ...  .. 15,470 9,111 
Calms to the 1000 do. aa. cee nee 4 21 


Total No. of observations ... ...| 63,050 | 55,327 113,240 166,829 


Average calms to the 1000 do. ... 41 | 24 39 25 


Periods Each one of these observations embraces a period of 
of the 2 5 . 
foregoing Cl@ht hours; the grand total, if arranged consecutively, 


tina ©With the observations drawn cut, each to occupy its 
period separately, would be equal to 373 years, They 
exhibit several curious and suggestive facts concerning 
the difference of the atmospherical stability in the two 
hemispheres. 

§1011 If we would discover the seat of those forces which 

Faust produce this difference in the dynamical status of the two 

ence or great aerial oceans that envelop our planet, we should 


force tn 


the winds search for them in the unequal distribution of land and 


TRADE-WINDS OF THE SOUTHERN HEMISPHERE. 451 


water over the two hemispheres. In one the wind is 
interrupted in its circuits by the continental masses, with 
their wooded plains, their snowy mantles in winter, their 
sandy deserts in summer, and their mountain ranges 
always. In the other there is but little land and less snow. 
On the polar side of 40° south especially, if we except the 
small remnant of this continent that protrudes beyond 
that parallel in the direction of Cape Horn, there is scarcely 
an island. All is sea. There the air is never dry; it is 
always in contact with a vapour-giving surface; conse- 
quently, the winds there are loaded with moisture, which, 
with every change of temperature, is either increased by 
further evaporation or diminished by temporary condensa- 
tion. The propelling power of the winds in the southern 
hemisphere resides chiefly wm the latent heat of the 
vapour which they suck up from the engirdling sea on 
the polar side of Capricorn. 

The Storm and Rain Charts show that within the 
trade-wind regions of both hemispheres the calm and rain 
curves are symmetrical; that in the extra-tropical regions 
the symmetry is between the calm and fog curves; and 
also, especially in the southern hemisphere, between the 
gale and rain curves. 

Lieutenant Van Gogh, of the Dutch navy, in an in- 
teresting paper on the connection between storms near 
the Cape of Good Hope and the temperature of the sea, 
presents a storm and rain chart for that region. It is 
founded on 17,810 observations, made by 500 ships, 
upon wind and weather, between 14° and 32° east and 
33° and 37° south. 


' De Stérmen nabij de Kaap de Goede Hoop in verband beschouwd met de 
Temperateur der Zee. 


CHAPTER 
xx. 


— 


Reason of 
the great- 
er propell- 
ing power 
of the 
winds of 
the south- 
ern hemi- 
sphere. 


Connec- 
tion be- 
tween 
stormsand 
the tem- 
perature 
of the sea 


CHAPTER 
xx. 


— 


§$ 1012 


Cause of 
the coun- 
ter trade- 
winds of 
the south- 
ern hemi- 
sphere. 


Average 
amount of 
precipita- 
tion. 


452 THE PHYSICAL GEOGRAPHY OF THE SEA, 


By that chart the gale and rain curves are so sym- 
metrical that the phenomena of rains and gales in the 
extra-tropical seas present themselves suggestively as 
cause and effect. The general storm and rain charts of 
the Atlantic Ocean, prepared at the National Observatory, 
hold out the same idea. Let us examine, expand, and 
explain this fact. 

We ascribe the trade-winds to the latent heat which 
is set free from the condensation of aqueous vapour in 
the equatorial calm-belt. But to what shall we ascribe 
the counter-trades, particularly of the southern hemi- 
sphere, which blow with as much regularity toward the 
Pole as the north-east trades of the Atlantic do toward 
the Equator? Shall we say that those winds are drawn 
toward the South Pole by eat, which causes them to 
expand and ascend in the Antarctic regions? It sounds 
somewhat paradoxical to say that heat causes the winds 
to blow toward the Poles as well as toward the Equator; 
but, after a little explanation, and the passing in review 
of a few facts and circumstances, perhaps the paradox 
may disappear. 

It is held as an established fact by meteorologists that 
the average amount of precipitation is greater in the 
northern than in the southern hemisphere; but this, I 
imagine, applies rather to the land than the sea. On the 
polar side of 40°, it is mostly water in the southern, 
mostly land in the northern hemisphere. It is only now 
and then, and on rare occasions, that ships carry rain- 
gauges to sea. We can determine by quantitive measure- 
ments the difference in amount of precipitation on the 
land of the two hemispheres; and it is the result of this 
determination, I imagine, that has given rise to the 


TRADE-WINDS OF THE SOUTHERN HEMISPHERE. 453 


general remark that the rain-fall is greater for the northern 
than it is for the southern hemisphere. But we have 
few hyetographic measurements for quantity at sea; 
there the determinations are mostly numerical. Our 
observers report the “times” of precipitation, which, 
whether it be in the form of rain, hail, or snow, is called 
by the charts, and in this discussion, rain. Among such 
a large corps of observers, rain is sometimes, no doubt, 
omitted in the log; so that in all probability the charts 
do not show as many “times” with rain as there are 
“times” actually with rain at sea. This omission, how- 
ever, is as likely to occur in one hemisphere as in the 
other. Still, we may safely assume that it rains oftener 
in all parts of the sea than our observations or the rain 
charts that are founded on them indicate. 

With the view of comparing the rains at sea between 
the parallels of 55° and 60°, both in the North and South 
Atlantic, we have taken from the charts the following 
fioures :— 


South—Observations, 8410; gales, 1228; rains, 1105. 


North— a3 OR YA LORE a5 64, 
Gales to the 1000 observations.....S. 146 ; N. 256. 
Rains op of ereeaweeloles N. 121. 


That is, for every 10 gales, there are in the southern 
hemisphere 9 rains, and in the northern 4.7. In which 
hemisphere does most water fall on the average during a 
rain at sea? Observations do not tell; but there seems 
to be a philosophical reason why it should rain not only 
oftener but more copiously at sea, especially in the extra- 
tropical regions, in the southern hemisphere, than in those 
of the northern. On the polar side of 40° north, for 
example, the land is stretched out in continental masses, 


CHAPTEB 
xX. 


$1013 


Compari- 
son of 
rains at 
sea, 


Reason 
why more 
rain 
should fall 
in the 
southern 
than in 
the north. 
ern hemi- 
sphere. 


454 THE PHYSICAL GEOGRAPHY OF THE SEA. 


cuarteR upon the thirsty bosom of which, when the air drops 
“down its load of moisture, only a portion of it can be 
ae * taken up again; the rest is absorbed by the earth to 
vrecn tne feed the springs. On the polar side of 40° south we have 
crews, & Water instead of a land surface, and as fast as precipita- 
tion takes place there, the ocean replenishes the air with 
moisture again. It may, consequently, be assumed that a 
high dew-point, at least one as high as the ocean can 
maintain in contact with winds blowing over it and 
going from warmer to cooler latitudes all the time, is the 
normal condition of the air on the polar side of 40° south, 
whereas on the polar side of 40° north a low dew-point 
prevails, The rivers to the north of 40° could not, if 
they were all converted into steam, supply vapour enough 
to make up this average difference of dew-point between 

the two hemispheres. 


Inference The symmetry of the rain and storm curves on the 


nnehs polar side of 40° south suggests that it is the condensation 

ee" of this vapour which, with the liberation of its latent 

m= heat, gives such activity and regularity to the circulation 
of the atmosphere in the other hemisphere. 

§1014 On the polar side of 40° south, near Cape Horn, the 
gauge of Captains King and Fitzroy showed a rain-fall of 
153.75 inches in 41 days. 

There is no other place except Cherraponjie where the 
precipitation approaches this in amount. Cherraponjie is 
a mountain station in India, 4500 feet high, which, in 
latitude 25° north, acts as a condenser for the monsoons 
fresh from the sea. But on the polar side of latitude 
45° in the northern hemisphere it is, except along the 
American shores of the North Pacific, a physical impossi- 
bility that there should be a region of such precipitation 


TRADE-WINDS OF THE SOUTHERN HEMISPHERE. 455 


as King and Fitzroy found on the western slopes of cHarrez 
XX. 


Patagonia—a physical impossibility, because the peculiar 
combination of conditions required to produce a Pata- 
gonian rain-fall is wanting on the polar side of 45° 
north. 

There is not in the North Atlantic water surface Causes 


why more 


enough to afford vapour for such an amount of precipita- rain fails 


tion. In the North Pacific the water surface may be scuba 
broad and ample enough to afford the vapour, but in sortie 
neither of these two northern sheets of water are the 
winds continuous enough from the westward to bring in 

the requisite quantities of vapour from the sea. More- 
over, if the westerly winds of the extra-tropical north 
were as steady and as strong as are those of the south, 
there is lacking in the north that continental relief— 
mountain ranges rising abruptly out of the sea, or sepa- 
rated from it only by lowlands—that seems to be necessary 

to bring down the rain in such floods. 


Colonel Sykes' quotes the rain-fall of Cherraponjie at Compari- 


son be- 
605.25 inches for the 214 days from April to October, tween the 
= rain-fall at 
the season of the south-west monsoons. Computing the cherra- 
5 ° . . ci ponjie 
Cape Horn rains according to the ratio given by King ancin pa 
tagonia, 


and Fitzroy for their 41 days of observation, we should 
have a rain-fall in Patagonia of 825 inches in 214 days, 
or a yearly amount of 1368.7 inches. Neither the Cape 
Horn rains nor the rains anywhere at sea on the polar 
side of 45° south are periodical. They are continuous ; 
more copious perhaps at some seasons than at others, but 
abundant at all. 

Now, considering the extent of water-surface on the § 1015 


1 “ Report of the British Association for 1852,” p. 256, 


CHAPTER 


Effect of 
tne moun- 
tains on 
the rains 
fall 


Effect of 
precipita- 
tion on 
the winds. 


§ 1016 


456 THE PHYSICAL GEOGRAPHY OF THE SEA. 


polar side of the south-east trade-wind belt, we see no 
reason why, on these parallels, the engirdling air of 
that great watery zone of the south should not, entirely 
around the earth, be as heavily charged with vapour 
as was that which dropped this flood upon the Pata- 
gonian hills. 

If those mountains had not been there, the condensa- 
tion and the consequent precipitation would probably not 
have been as great, because the conditions at sea are less 
apt to produce rain; but the quantity of vapour in the 
air would have been none the less, which vapour was 
being borne in the channels of circulation toward the 
Antarctic regions for condensation and the liberation of 
its latent heat; and we make, as we shall proceed to 
show, no violent supposition if, in attempting to explain 
this activity of circulation south of the Equator, we sup- 
pose a cloud region, a combination of conditions in the 
Antarctic Circle peculiarly favourable to heavy and almost 
incessant precipitation. ; 

But before describing these conditions, let us turn 
aside to inquire how far precipitation in the sup- 
posed cloud region of the south may assist in giving 
force and regularity to the winds of the southern hemi- 
sphere. 

If we take a measure, as a cubic foot, of ice at zero, 
and apply heat to it by means of a steady flame that 
will give off heat at a uniform rate, and in such quanti- 
ties that just enough heat may be imparted to the ice to 
raise its temperature 1° a minute, we shall find that at 
the end of 32 minutes the ice will be at 32°. The ice 
will now begin to melt, but it and its water will remain 
at 32° for 140 minutes, when all the ice will have become 


TRADE-WINDS OF THE SOUTHERN HEMISPHERE. 457 


water at 32°! This 140° of heat, which is enough to cuaprer 
fo) 


raise the temperature of 140 cubic feet of ice one degree 
from any point below 32°, has been rendered latent in the 
process of liquefaction. Freeze this water again, and 
this latent heat will become sensible heat; for heat no 
more than ponderable matter cannot be annihilated. 

But if, after the cubic foot of ice has been converted 
into water at 32°, we continue the uniform supply of 
heat as before, and at the same rate, the water will, at 
the expiration of 180 minutes more, reach the tempera- 
ture of 212°—the boiling-point ; and at this temperature 
it will remain for 1030 minutes, notwithstanding the con- 
tinuous supply of heat during the interval. At the 
expiration of this 10380 minutes of boiling heat, the last 
drop of water will have been converted into steam ; but 
the temperature of the steam will be that only of the 
boiling water: thus, in the evaporation of every measure 
of water, heat enough is rendered latent during the pro- 
cess to raise the temperature of 1030 such measures 
one degree. If this vapour be now condensed, this 
latent heat will be set free, and become sensible heat 
again. 

Hence we perceive that every rain-drop that falls from 
the sky had in its process of condensation evolved heat 
enough to raise one degree the temperature of 1030 
rain-drops. But if, instead of the liquid state, as rain, it 
come down in the solid state, as hail or snow, then the 
heat of fluidity, amounting to enough to raise the tem- 
perature of 140 additional drops one degree, is also 
set free. 


1 See Espy’s ‘‘ Philosophy of Storms.” 


xXx. 


Heat 
evolved by 
every rain 
drop in its 
precipita- 
tion, 
whether 
as rain or 
slow. 


458 THE PHYSICAL GEOGRAPHY OF THE SEA. 


cuarter = We have in this fact a clue to the violent wind which 
usually accompanies hail-storms. In the hail-storm, con- 


Cause of : ° : . 
the vio. gelation takes place immediately after condensation, and 
lent wind : ‘ 

whien SO quickly, that the heat evolved during the two pro- 
sual] . . 

acm cesses may be considered as of one evolution. Con- 
panies 
haii- 
storms, 


sequently, the upper air has its temperature raised much 
higher than could be done by the condensing only. 

But this is digressive ; therefore let us take up the 
broken thread, and suppose, merely for illustration, such 
a rain-fall as King and Fitzroy encountered in Patagonia 
to have taken place under the supposed cloud region of 
the Antarctic Circle, and to have been hail or snow, in- 
stead of rain; then the total amount of caloric set free 
among the clouds, in those 41 days of such a flood, 
would be enough to raise from freezing to boiling 64 
times as much water as fell. But if the supposed 
Antarctic precipitation come down in the shape of rain, 
then the heat set free would be sufficient only to raise 
from freezing to boiling about 53 as much water as the 
flood brought down. 

§ 1017 We shall have perhaps a better idea of the amount 
heat et Of heat that would be set free, in the condensation 
eae and congelation in the Antarctic regions of as much 
conde. Vapour as it took to make the Patagonian rain-fall, if 
vapour, We vary the illustration by supposing this rain-fall of 

153.75 inches to extend over an area of 1000 square 
miles, and that it fell as snow or hail. The latent heat 
set free among the clouds during these 41 days would 
have been sufficient to raise from the freezing to the 
boiling point all the water in a lake 1000 square miles 
in area and 83% feet in depth. We now see how the 
cold of the Poles, by facilitating precipitation, is made to 


TRADE-WINDS OF THE SOUTHERN HEMISPHERE, 459 


react and develop heat, to expand the air and give cuarrer 
. XX. 
force to the winds. size 
Thus we obtain another point of view from which § 1018 
we may contemplate in a new aspect the icebergs 


which the antarctic region sends forth in such masses and 


numbers. 
They are a part of the meteorological machinery of osicss 
5 performed 
our planet. The offices which they perform as such are py ice- 


most important, and oh, how exquisite! While they are 


in the process of congelation, the heat of fluidity is set 
free, which, whether it be liberated by the freezing of 
water at the surface of the earth, or of the rain-drop in 
the sky, helps in either case to give activity and energy 
to the southern system of circulation, by warming and 
expanding the air at its place of ascent. 

Thus the water, which, by parting with its heat of use of ice. 
liquefaction, has expended its meteorological energy in coejite 


water froin 


civing dynamical force to the air, is like the exhausted north to 
steam of the engine; it has exerted its power, and °"™ 
become inert. It is, therefore, to be got out of the way. 
In the grand meteorological engine which drives the 
wind through his circuits, and tempers it to beast, bird, 
and plant, this waste water is collected into antarctic 
icebergs, and borne away by the currents to more genial 
climes, where the latent heat of fluidity which they dis- 
pense to the air in the frigid zone is restored, and where 
they are again resolved into water, which, approaching 
the torrid zone in cooling streams, again joins in the 
work, and helps to cool the air of the trade-winds, to 
mitigate climate, and moderate the gale. For if the 
water of southern seas were warmer, evaporation would 
be greater; then the south-east trade-winds would de- 


460 THE PHYSICAL GEOGRAPHY OF THE SEA 


cuarter liver vapour more abundantly to the equatorial calm 
=** belts. This would make precipitation there more copious, 
and the additional quantity of heat set free would give 
additional velocity to the in-rushing trade-winds. Thus 
it is, as has already been stated, that, parallel for parallel, 
trans-equatorial seas are cooler than cis-equatorial ; thus 
Effect of 1t is that icebergs are employed to push forward the 
cnwini, winds in the polar regions, to hold them back in the 
equatorial; and thus it is that, in contemplating the 
machinery of the air, we perceive how icebergs are 
“coupled on,” and made to perform the work of a 
reguiator, with adjustments the most beautiful, and com- 
pensations the most exquisite, in the grand machinery of 

the atmosphere. 
§1019 With this illustration concerning the dynamical force 
cate Which the winds derive from the vapour taken up in 


which the . 
windsde- Oe Climate and transported to another, we may pro- 


ive fr 5 C ; 
vapour, ceed to sketch those physical features, which, being found 
in the antarctic circle, would be most favourable to heavy 
and constant precipitation, and, consequently, to the de- 
velopment of a system of aerial circulation peculiarly active, 
vigorous, and regular for the aqueous hemisphere, as the 
southern, in contrast with the northern one, may be called. 
Thecoun- ‘These vapour-bearing winds, which brought the rains 
ter-trade 5 C ° . 
windsof to Patagonia are—I wish to keep this fact in the 
the south- ) 5 ; . 
ern hemis Teader’s mind—the counter-trades of the southern hemi- 
sphere are : x: 
viene sphere. As such they have to perform their round in the 
bearing : ° ° : 
wing grand system of aerial circulation; and as in every 
system of circulation there must be some point or place 
at which motion ceases to be direct, and commences to 
be retrograde, so there must be a place somewhere on 


the surface of our planet where these winds cease to go 


TRADE-WINDS OF THE SOUTHERN HEMISPHERE. 461 


forward, stop, and commence their return to the north; cnaprer 
and that place is, in all probability, within the antarctic ** 
regions. Its precise locality has not been determined, oer 
but I suppose it to be a band or disk within the polar tHe wisda 
circle, which, could it be explored, would be found, like 

the equatorial calm belts, a place of light airs and calms, 

of ascending columns of air, a region of clouds and of 
constant precipitation. 

But, be that as it may, the air which these vapour- 

bearing winds—vapour-bearing, because they blow over 
such an immense tract of ocean—pour into this stopping- 
place has to ascend and flow off as an upper current, to 
make room for that which is continually flowing in 
below. In ascending it expands and grows cool, and, as 
it grows cool, condensation of its vapour commences. 
With this vast quantities of latent heat, which converted 
the water out at sea into vapour for these winds, are set 
free in the upper air. There it reacts by warming the 
ascending columns, causing them still further to expand, 
and so to rise higher and higher. 

This reasoning is suggested not only by the facts § 1020 
and circumstances already stated as well known, but it 
derives additional plausibility for correctness by the 
low barometer of these regions. 

In the equatorial calm belts the mean barometric pres- pitterence 


of barome- 


sure is about 0.2 inch less than it is in the trade-winds, tric pres- 
and this diminution of pressure is enough to create a tam belts 
perpetual influx of the air from either side, and tof" "" 
produce the trade-winds. Off Cape Horn the mean “* 


barometric pressure’ is 9.75 inch less than in the trade- 


1“ Maury’s Sailing Directions,” 6th ed., 1854, p. 692; ditto, 8th ed., 1859, 
vol. li. p. 450. 


CHAPTER 
xx. 


Diminu- 
tion of at- 
mospheri- 
cal pres- 
sure in 
high south 
latitudes, 


462 THE PHYSICAL GEOGRAPHY OF THE SEA, 


wind regions. This is for the parallel say of 57°—8° 
south, According to the mean of 2472 barometric 
observations made along that part only of the route to 
Australia which lies between the meridians of the Cape 
of Good Hope and Melbourne, the mean barometric pres- 
sure on the polar side of 42° south has been shown by 
Lieutenant Van Gogh, of the Dutch navy, to be 0.383 
inch less than it is in the trade-winds. The mean pres- 
sure in this part of the South Indian Ocean is, under 
winds with easting in them, 29.8 inches; ditto, under 
winds with westing, 29.6 inches. This gives a supposed 
mean pressure in the polar calms of 29.7 inches. 

To what, if not to the effects of the condensation of 
vapour borne by those surcharged winds, and to the 
immense precipitation in the Austral regions, shall we 
ascribe this diminution of the atmospherical pressure in 
high south latitudes? It is not so in high north lati- 
tudes, except about the Alentian Islands of the Pacific, 
where the sea to windward is also wide, and where 
precipitation is frequent, but not so heavy. The steady 
flow of “brave” winds toward the south would seem to 
eall for a combination of physical conditions about their 
stopping-place exceedingly favourable to rapid and heavy 
and constant precipitation. The rain-fall at Cherraponjie, 
and on the slopes of the Patagonian Andes, reminds us 
what those conditions are. There mountain masses seem 
to perform, in the chambers of the upper air, the office 
which the jet of cold water does for the exhausted steam 
in the condenser of the engine. ‘The presence of land, 
not water, about this south polar stopping-place is, there- 
fore, suggested ; for the sea is not so favourable as the 
mountains are for aqueous condensation. 


TRADE-WINDS OF THE SOUTHERN HEMISPHIRE. 468 


By the terms in which our proposition has been sae 
stated, and by the manner in which the demonstration — 
has been conducted, the presence of land in large masses 
there is called for; and, if we imagine it to be relieved 
by high mountains and lofty peaks, we shall have in 
the antarctic continent a most active and powerful 
condenser. 

If, again, we tax imagination a little further, we may, 
without transcending the limits of legitimate speculation, 
invest that unexplored land with numerous and active 
volcanoes. If we suppose this also to be the case, then 
we certainly shall be at no loss for sources of dynamical 
force sufficient to give that freshness and vigour to the 
atmospherical circulation which observations have abun- 
dantly shown to be peculiar to the southern hemisphere. 
Neither under such physical aspects need it be any longer Cause of 


* : . the polar 
considered paradoxical to ascribe the polar tendency of tendency 


the “ brave west winds” to rarefaction by heat in the tae 
Antarctic Circle. This heat is relative, and though it be ¥inis» 
imparted to air far below the freezing-point, raising its 
temperature only a few degrees, its expansive power for 

that change is as great when those few degrees are low 
down as it is when they are high up on the scale. 

If such condensation of vapour do take place, then 
liberation of heat and expansion of air must follow, and Alteration 
consequently the oblateness of the atmospherical cover- eee 
ing of our planet will be altered; the flattening about See 
the Poles will be relieved by the intumescence of the crour 
expanded and ascending air, which, protruding above the?" 
general level of the aerial ocean, will receive an impulse 
equatorially, as well from the mere derangement of equi- 


librium as from the centrifugal forces of the revolving 


CHAPTER 
xx, 


§ 1021 


An ever- 
lasting cy- 
clone ona 
gigantic 
scale. 


The pur- 
poses 
which God 
designs to 
accome- 
plish seen 
in his ar- 
range-= 
ments. 


464 THE PHYSICAL GEOGRAPHY OF THE SEA. 


globe. And so this air, having parted with its moisture, 
and having received the expansive force of all the latent 
heat evolved in the process of vaporous condensation, 
will commence its return toward the Equator as an 
upper current of dry air. 

Arrived at this point of the investigation, we may 
contemplate the whole system of these “brave west 
winds” in the light of an everlasting cyclone on a 
gigantic scale. The antarctic continent is in its vortex, 
about which the wind, in the great atmospherical ocean 
all around the world, from the Pole to the edge of the 
calm belt of Capricorn, is revolving in spiral curves, con- 
tinually going with the hands of a watch, and twisting 
from left to right. 

In studying the workings of the various parts of the 
physical machinery that surrounds our planet, it is 
always refreshing and profitable to detect, even by glim- 
merings never so faint, the slightest tracings of the 
purpose which the omnipotent Architect of the universe 
designed to accomplish by any particular arrangement 
among its various parts. Thus it is in this instance. 
Whether the train of reasoning which we have been 
endeavouring to follow up, or whether the arguments 
which we have been adducing to sustain it be entirely 
correct or not, we may from all the facts and circumstances 
that we have passed in review, find reasons sufficient for 
regarding in an instructive, if not in a new light, that 
vast waste of waters which surrounds the unexplored 
regions of the Antarctic Circle. 

It is a reservoir of dynamical force for the winds, 


a regulator in the grand meteorological machinery of the 
garth. 


TRADE-WINDS OF THE SOUTHERN HEMISPHERE. 465 


The heat which is transported by the vapours with carrer 
. . . ee A xx, 
which that sea loads its superincumbent air is the chief — 
: : 22 
source of the motive power which gives to the winds of s 1022 


Heat the 


the southern hemisphere, as they move through their ‘"* 
source of 


channels of circulation, their high speed, great regularity, the mote 
P 5 7d 5 ? power of 


and consistency of volume. And this insight into the the winds 
workings of the wonderful machinery of sea and air we south 
obtain from comparing together the relative speed of 
vessels as they sail to and fro upon inter-tropical seas. 

Such is the picture which, after no little labour, much § 1023 
research, and some thought, the winds have enabled us 
to draw of certain unexplored portions of our planet. 
As we have drawn the picture, so, from the workings of 
the meteorological machinery of the southern hemisphere, 
we judge it to be. The evidence which has been intro- Evidence 
duced is meteorological in its nature, circumstantial in eee 
its character, we admit; but it shows the idea of land in es 
the antarctic regions—of much land, and high land—to rnin 
be plausible at least. Not only so: it suggests that a "°"* 
group of active volcanoes there would be by no means 
inconsistent with the meteorological phenomena which 
we have been investigating. True, volcanoes in such 
a place may not be a meteorological necessity. We 
cannot say that they are; yet the force and regularity of 
the winds remind us that their presence there would not be 
inconsistent with known laws. According to these laws, 
we may as well imagine the Antarctic Circle to encompass 
land as to encompass water. We know ocularly but 
little more of its topographical features than we do of 
those of one of the planets; but, if they be continental, 
we surely may, without any unwarrantable stretch of the 


imagination, relieve the face of nature there with snow- 
30 


466 THE PHYSICAL GEOGRAPHY OF THE SEA. 


ee clad mountains, and diversify the landscape with flaming 
— volcanoes. 

None of these features are inconsistent with the 
phenomena displayed by the winds. Let us apply to 
other departments of physics, and seek testimony from 
other sources of information. None of the evidence to 
be gathered there will appear contradictory, it is rather in 

Testimony corroboration. Southern explorers, as far as they have 

eee penetrated within the Antarctic Circle, tell us of high 
lands and mountains of ice; and Ross, who went furthest 
of all, saw volcanoes burning in the distance. 

§ 1024 The unexplored area around the South Pole is 


Extent of : C < 
the unexe about twice as large as Europe. This untravelled region 


lored . . . o = 
trea ofthe 18 Circular in shape, the circumference of which does not 


south el measure less than 7000 miles. Its edges have been 
penetrated here and there, and land, wherever seen, has 
been high and rugged. 

Navigators on the voyage from the Cape of Good Hope 
to Melbourne, and from Melbourne to Cape Horn, scarcely 
ever venture, except while passing Cape Horn, to go on 
the polar side of 55° south. The fear of icebergs deters 
Icebergs them. These may be seen there drifting up towards the 


in the 
southera ~Hquator in large numbers and large masses all the year 


“round. I have encountered them myself as high up as 
the parallel of 37° south. 

The belt of ocean that encircles this globe on the polar 
side of 55° south is never free from icebergs. They are 
found in all parts of it the year round. Many of them 
are miles in extent, and hundreds of feet thick. The 
area on the polar side of the 55th parallel of south 
latitude comprehends a space of 17,784,600 square miles. 


The nursery fer the bergs, to fill such a field, must be an 


TRADE-WINDS OF THE SOUTHERN HEMISPHERE. 467 


immense one; such a nursery cannot be on the sea, for cuarrer 
icebergs require to be fastened firmly to the shore until a 
they attain full size. They, therefore, in their mute 
way, are loud with evidence in favour of antarctic shove 
lines of great extent, of deep bays where they may be 
formed, and of lofty cliffs whence they may be launched. 

There is another physical circumstance which obtains pProbavi- 
generally with regard to the distribution of land and tienes af 


an antarc- 


water over the surface of the earth, and which, as far as tic conti. 
it goes, seems to favour the hypothesis of much land" 
about the South Pole; and that circumstance is this: It 
seems to be a physical necessity that land should not be 
antipodal to land. Except a small portion of South 
America and Asia, land is always opposite to water. 
The belief is, that on the polar side of 70° north we have 
mostly water, not land. This law of distribution, so far 

as it applies, is in favour of land in the opposite zone. 
Finally, geographers are agreed that, irrespective of the 
particular facts and phenomena which we have been con- 
sidering, the probabilities are in favour of an antarctic 
continent rather than of an antarctic ocean. 

“There is now no doubt,” says Dr. Jilek, in his pr. siteks 
“Lehrbuch der Oceanographie,” “that around the South ee 
Pole there is extended a great continent mainly within ’** 
the polar circle, since, although we do not know it in its 
whole extent, yet the portions with which we have 
become acquainted, and the investigations made, furnish 
sufficient evidences to infer the existence of such with 
certainty. This southern or antarctic continent advances 
furthest northward in a peninsula south-south-east of the 
southern end of America, reaching in Trinity Land almost 
to 62° south latitude. Outwardly these lands exhibit a 


468 THE PHYSICAL GEOGRAPHY OF THE SEA. 


cnarrer naked, rocky, partly volcanic desert, with high rocks 
destitute of vegetation, always covered with ice and 
snow, and so surrounded with ice that it is difficult or 
impossible to examine the coasts very closely. .... 
Bittore2 “The principal discoveries of these coasts are (Wilkes), 
ee” Dumont d’Urville, and Ross (the younger), of whom the 
sonth pole. Jatter in 1842 followed a coast over 100 miles between 
72° and 79° south latitude, and 160° and 170° east 
longitude, to which he gave the name Victoria Land, and 
on which he discovered a volcano (Erebus) 10,200 feet 
high, in 167° east longitude, and 77° south latitude, as 
well as another extinct one (Terror) 10,200 feet high, 
and then discovered the magnetic South Pole.’'—Obser- 
vatory, Washington, April, 1859. 


1“ Text-book of Oceanography for the Use of the Imperial Naval Academy,” 
by Dr. August Jilek, Vienna, 1857. 


THE ATLANTIC TELEGRAPH. 469 


CHAPTER XXI. 


THE SUBMARINE TELEGRAPH OF THE ATLANTIC. 


Its History, § 1025.—Attempt to be renewed, 1026.—Causes of Failure, 1027. 
—The Probabilities of Success, 1028.—The real Question, 1029. 


THE Atlantic Telegraph quietly rests on its plateau, cuarrer 


. . XXII. 

after having performed its office as a channel of —_ 
Rie : = -, § 1025 
communication only for a short time. The laying of it}. 3.0". 


was celebrated with a pomp and circumstance in New pa 
York seldom, if ever, witnessed. Though short-lived it 
was a grand achievement. It demonstrated the possibility 
of uniting, by a telegraph across the Atlantic, the New 
World with the Old. Everything that contributed 
toward the accomplishment of this achievement is 
possessed of that peculiar interest which attaches to the 
history of great events. 

It is in some sort a result arising from these researches 
concerning the physics of the sea, and a short account of 
it may be given here without prejudice to the specialties 
of this work. 

On the Ist of September, before an immense assembly ttsnistory. 
of people in the Crystal Palace of New York, the history 
of this telegraphic enterprise was given, in a speech of 
much beauty and eloquence, by David Dudley Field, for 
and in behalf of the Company—he being one of the 
original projectors. 

In 1854, he and his associates had under consideration First sus. 
a line from our own shores to Newfoundland, when the ea 
idea of extending it across the Atlantic was suggested ; 


470 THE PHYSICAL GEOGRAPHY OF THE SEA. 


cuarter but before they decided upon anything they wrote, said 

** the orator, “to Lieutenant Maury, to inquire about the 
hectare sex practicability of submerging a cable, and consulted Pro- 
Lieuten- fessor Morse about the possibility of telegraphing through 


ant Mau- 
ry'sopin’ it, Their answers were favourable. On receiving them 


ion, which  * 


is favour it was decided to ‘go ahead.’ ” 
It thus appears that this new department of science, 

embodied in the term “ Physical Geography of the Sea,” 
has already contributed to the advancement of one of the 
grandest and most interesting practical problems which 
this age of mind and intelligence has been called on to 
demonstrate. 

Steamers In the summer of 1857, the United States steamer 

BreGe “Niagara” and H. B. M. steamer “Agamemnon” were 

catie. assigned by their respective governments to the duty of re- 
ceiving on board and laying the Submarine Atlantic Cable. 
Other vessels were sent with them as pilots, consorts, and 
tenders. The plan was, for the “Niagara” to begin at 
Queenstown, Ireland, pay out her cable as far as it would 
reach, then pass the end in mid-ocean to the “Agamemnon,” 
when it would be spliced, and when that ship would 
proceed with it to Newfoundland. After reaching deep 
water, the “Niagara” having paid out about 344 miles of 

First fail- cable, it parted August 11th, 1857. This failure post- 

ae poned further trial till the summer of 1858. 

second at- In the summer of 1858, the same two ships, having 

"EP the cable again on board, proceeded together to mid- 
ocean, where the two ends were joined, and they then 
commenced to “pay and go,” each toward her own land. 
The “Niagara” had 1488 miles of cable on board, the 
“Agamemnon” 1477. Total, 2965 miles. 


After three unsuccessful attempts to lay the cable, and 


THE ATLANTIC TELEGRAPH. 471 


after the loss of about 400 miles of it, the fleet returned cnarre 
to Ireland. It put to sea again for a last trial, July 17, 2 
with about 1274 miles of cable on board each of the 
paying-out vessels. 

They met in mid-ocean, joined cables, and set out,— 
the “Niagara” for her terminus in Trinity Bay, and the 
“Agamemnon” for hers in Valentia Harbour,—at 1 P.M, 
July 29th, and successfully landed each vessel her end of Suscesiat 
the cable on the 5th of August. One week after that a 


messages of congratulation were passed through the First mes 
cable between the Queen of England and the President = 
of the United States. 

The part which the Observatory has played in the The con- 
history of submarine telegraphy, and of this line between he Oe 
the Old World and the New, is a quiet and an humble With ine 
part ; nevertheless, it now appears to have been an im- aa 
portant and useful part. But, whatever it may have 
been, it has grown out of that beautiful system of 
research concerning the physics of the sea, which, having 
its commencement here in 1842, has expanded and 
blossomed, and fruited, giving among its fruits for man’s 
benefit charts of the winds and currents of the sea, and 
secrets snatched from its depths. The present, therefore, 
seems to be a proper time for placing on record a state- 
ment showing the connection of the Observatory with 
this enterprise, and the part borne in it by each one who 
has helped this institution to render good service in such 
a field. 

In 1849 the labours of the Observatory in the hydro- 
graphical department of its duties appear to have attracted 
the favourable consideration of Congress; for in March 
of that year a law was passed directing the secretary of 


472 THE PHYSICAL GEOGRAPHY OF THE SEA. 


cuarter the navy “to detail three suitable vessels of the navy in 
XXL . . . . 
testing new routes and perfecting the discoveries made 


Law pa . . ont tye . ° 
iby by Lieutenant Maury in the course of his investigations 
Congress 
to aid the 
investiga- 
tions of the 


Ovserva- for such investigations, in so far as said co-operation may 


of the winds and currents of the ocean ; and to cause the 
vessels of the navy to co-operate in procuring materials 


tory. 

not be incompatible with the public interest.” 
The Under this law the United States schooner “Taney,” 
schooner 


“Taney” Lieutenant J. C. Walsh commanding, was sent to sea in 
make 1849. She was directed, among other things, to make 
emne™ series of deep-sea soundings. She was _ provided, 
therefore, with fourteen thousand fathoms of steel wire, and 
a self-registering deep-sea sounding apparatus, made by 
Mr. Baur, of New York, from drawings and according to 
a plan designed in this office. She got a cast with 5700 
fathoms of line out, when it parted, losing the apparatus. 
She then proved unseaworthy, was condemned, and sent 
back under escort. 
Longing This reported sounding served to stimulate that longing 
enone which is implanted in the human breast touching the 
nee mysteries and the wonders of the great deep; for up to 
this time no systematic attempt had ever been made to 
fathom the deep sea. Sporadic casts of the lead had 
been made here and there in “blue water,” but though 
the reported depths had been great, yet, as with that of 
the “Taney,” there always remained a doubt as to whether 
bottom had been reached or not, and at what depth. Up 
to this time we were as ignorant as to the real depths of 
the ocean, and the true character of that portion of the 
solid crust of our planet which constitutes its bed, as we 
are at this moment of tle interior of one of the satellites 


of Jupiter. Using astronomical elements, the mean depth 


THE ATLANTIC TELEGRAPH. 473 


of the ocean had been calculated to be, according to carrer 
theory, about 23 miles. arin 

My excellent friend, the late Commodore Warrington, 

who was then the chief of the Bureau of Ordnance and 
Hydrography, of which the Observatory is a branch, took, 
as was his wont, liberal and enlightened views touching 
the plan of deep-sea soundings now proposed. The 
secretary of the navy regarded it with a lively interest ; 
he was ready to afford every facility that the law 
required, and the law itself was liberal enough. Under 
such auspices, it was decided to inaugurate a regular plan a regular 
of deep-sea sounding for the American navy. <Accord- iene 
ingly, formule were arranged, methods prescribed, and ae 
our men-of-war were furnished with the requisite twine, 
&c., and commanded to use every suitable and convenient 
opportunity while at sea to try the depths of its deep 
waters. Each vessel was allowed a number of reels of 
this twine, according to her cruising ground, each reel 
containing ten thousand fathoms, weighing about one 
hundred pounds. 

Under this order, Lieutenant William Rogers Taylor, A series of 
the 1st of the “Albany,” Captain Platt, commenced a series cee 
of soundings in and about the gulf of Mexico; Captain cai 
Barron, of the “John Adams,” ran a line across the Atlantic; 
and Captain Walker, of the “Saratoga,” gota cast in the 
South Atlantic. 

All these soundings required verification; and in 1851 
the “Dolphin,” Lieutenant-commanding §. P. Lee, was fitted 
out, under the act of 1849, especially to assist me with 
observations and experiments. After many trials, and as 
many failures, she at last succeeded in getting good 


casts, which, being reliable, enabled me to establish a law 


4°7 4 THE PHYSICAL GEOGRAPHY OF THE SEA. 


cuapter Of descent for the plummet, and so prove the soundings 
= of other vessels. 

Suecessof Lieutenant Lee, having thus “made the egg stand on 

nant ie 168 end,” returned home, bringing with him the best series 
of deep-sea soundings that up to that time had ever been 
made; and they have not been surpassed by any up to 
this day. 

The “Dolphin” was then placed under the command of 

Lieutenant O. H. Berryman, to continue this service. 
With Lee’s plans and experience to guide him, he put to 
sea from New York, October 1852, sounding as he went 
as far as the meridian of 40° west, where he was over- 
taken by a gale, damaged, and forced into the Tagus for 
repairs. Here he remained till December 19th, and then 
returned home by the southern route, sounding and look- 
ing for “vigias” as he came. 

An oro- With Lee’s soundings in the “Dolphin,” together with 

graphic 


map con- those already obtained from the regular cruisers in the 


structed of ° . 
the bed of NAVY, 1 was enabled, with the assistance of Professor 


Atuatic Elye, to construct, in the fall of 1852, an orographic map 

Orca of the bed of the North Atlantic Ocean, and to give a 
profile representing a vertical section of its bottom 
between this country and Europe near the parallel of 39° 
north. 

The mate. Lhe materials used for this map? and profile were the 

forthe deep-sea soundings already mentioned as made by Walsh, 

a Taylor, Lee, and Barron, together with others which had 
been received from the “Congress,” Commodore M‘Keever ; 
the “Portsmouth,” Captain Dornin ; the “Cyane,” Captain 


Paine; the“St. Louis,” Captain Ingraham; the “Plymouth,” 


1 See Plates XIV. and XY., ‘‘ Maury’s Sailing Directions,” 5th edition. 


THE ATLANTIC TELEGRAPH. 475 


Captain Kelly; the “Germantown,” Captain Knight ; the cuaprer 
“Susquehanna,” Captain Inman ; and Lieutenant Warley, ae 
of the “Jamestown,” Captain Downing. These were the 

first maps of the kind ever attempted for “blue water.” 
Their object was to show the depressions of the solid 
crust of our planet below, as geographers seek to repre- . 
sent its elevations above the sea-level The “ telegraphic 
plateau” is there delineated on Plate XIV., very much as 

the subsequent deep-sea soundings have shown it to be. 

This attempt to map out the bottom of the deep sea was 
regarded with exceeding interest by the learned. Hum- Hum- 


boldt’s in- 
boldt gave it high praise ; it opened the freshest and most terest in 


interesting field that remained to him for contemplation foc 
in the domains of science. 

Up to this time, however, nothing had ever been 
brought up from the deep sea. The plummet wasa can- 
non-ball, and the sounding-line a bit of small twine which 
was broken off when the cannon-ball reached the bottom, 
so that ball and twine remained behind ; consequently, 
every cast of the deep-sea plummet involved the loss of 
a shot and of as much twine as it took to reach the 
bottom. It was desirable to bring up soundings, not 
only that we might learn what the bottom and bed of 
the ocean were made of, but that we might know of a 
verity and have the proof that the bottom had been 
reached. 

Under these circumstances, the attention of Lieutenant contriy- 
J. M. Brooke, who was at the time stationed at the Ob- aueee 

up speci- 


servatory, was called to the subject, when he made, for mens fiom 


° e e . the bott 
bringing up specimens from the bottom, the beautiful and ¢rine 


————— een ae 
‘See p. 239, 240, 5th ed. ‘‘ Maury’s Sailing Directions,” printed by C. 
Alexander, Washington, and published in February 1853, 


476 THE PHYSICAL GEOGRAPHY OF THE SEA, 


cuarter simple contrivance known as “ Brooke’s deep-sea sounding 
apparatus.” 

the“pok When the “Dolphin” returned from the Tagus, which she 

eae to aid in March 1858, arriving at Norfolk on the 7th of 

sea to ob- that month, she was ordered to sea again under Berry- 


mets man, to assist still further “in perfecting the discoveries 
made by Lieutenant Maury in the course of his investiga- 
tion of the winds and currents of the ocean.” And that 
I might procure specimens of the bottom, this apparatus 
of Brooke was put on board the “Dolphin;” and this was 
the first time that it was put on board any vessel. The 
first time it was used was at 1.20 p.m, July 7, 1853, in 
latitude 54°17’ north, longitude 20° 33’ west, by J. G. 
Mitchell, then a midshipman on board that brig. This 
sounding, as were all since Lee’s time, was made from a 
boat; it occupied six hours. The depth was 2000 
fathoms, and the rod came up, its arming loaded with 
precious trophies. This promising young officer made 
every deep-sea sounding that was made in the “Dolphin” 
during that cruise, save one only, and to him belongs the 

Thefirst honour of bringing up the first specimen that was ever 

obtained, Obtained from the bottom of the deep sea. Subsequently, 
during this cruise, several other specimens were obtained; 
but the first was described by Mitchell as “a fine chalky 
clay.” 

The “Dolphin” returned in November 1853. Her 
soundings during these two cruises with Brooke’s ap- 
paratus were first published in the sixth edition of “ Sail- 
ing Directions,” March 1854, The specimens from the 
bottom were forwarded to the Observatory, and by me 
sent to that charming man of science, the late Professor 
Bailey, of West Point, for examination under his micro- 


THE ATLANTIC TELEGRAPH. 477 


scope. He examined them, and found those specimens cmarter 
XXI. 

from the bottom of the great deep not to have “a par- 

ticle of sand or gravel mixed with them,” but to be mites 


The speci- 
mens from 
the bed of 
the ocean 


of sea-shells, perfect in form, and as unworn and un- 
triturated as they were when alive. en 
This discovery of the miscroscope at once suggested ‘sre 
the idea that there is no running water, no abrading 
forces at play upon the bottom and bed of the deep sea ; 
and consequently that, if an electric cord were ever 
lodged upon the telegraphic plateau, there it would lie in 
cold obstruction, without anything to fret, chafe, or wear, 
save alone the tooth of time. 
Accordingly, when, in February 1854, the projectors of 
the Atlantic Telegraph inquired of me “about the prac- 
ticability of submerging the cable,” I was enabled to 
reply as follows:— 
“ From Newfoundland to Ireland the distance between tieu- 
the nearest points is about sixteen hundred miles, and iacae 


opinion 


the bottom of the sea between the two places is a plateau, about ine 
which seems to have been placed there especially for the ars 
purpose of holding the wires of a submarine telegraph 
and of keeping them out of harm’s way. It is neither ¢t" 
too deep-nor too shallow ; yet it is so deep that the wires 
being once landed, will remain for ever beyond the reach 
of vessels’ anchors, icebergs, and drift of any kind, and 
so shallow that the wires may be readily lodged upon the 
bottom. 

“The depth of this plateau is quite regular, gradually 
increasing from the shores of Newfoundland to the depth 
of from fifteen hundred to two thousand fathoms as you 
approach the other side. 

“ Whether it be better to lead the wires from New- 


submergs 
ing the 


478 THE PHYSICAL GEOGRAPHY OF THE SEA. 


carrer foundland or Labrador is not now the question; nor do I 


The 
American 
system of 
deep sea 
soundings 
adopted 
by other 
gavies, 


pretend to consider the question as to the possibility of 
finding a time calm enough, the sea smooth enough, a 
wire long enough, and a ship big enough to carry and lay 
a coil of wire 1600 miles in length. I simply address 
myself at this time to the question in so far as the bottom of 
the sea is concerned ; and as for that, the greatest practical 
difficulty will, I apprehend, be found after reaching sound- 
ings at either end of the line, and not in the deep sea. 

“A wire laid across from either of the above-named 
places on this side would pass to the north of the Grand 
Banks and rest on that beautiful plateau to which I have 
alluded, and where the water of the sea appears to be as 
quiet and as completely at rest as it is at the bottom of 
a mill-pond. 

“Therefore, so far as the bottom of the deep sea be- 
tween Newfoundland or the mouth of the St. Lawrence 
and Ireland is concerned, the practicability of a submarine 
telegraph across the Atlantic is proved.” 

The letter from which these extracts are taken is dated 
at the Observatory, 23d February 1854, and was ad- 
dressed to Professor Morse. 

The system of deep-sea soundings thus inaugurated has 
been adopted by the English, Dutch, Austrian, and all 
other navies that have since entered with us in this new 
field. From this simple beginning and in this short time, 
more knowledge has been gained for man concerning the 
depths and bottom of the ocean than he had acquired in 
all previous time. The English and French by their 
deep-sea soundings have given us materials for orographic 
maps of the basins which hold the Mediterranean and the 
Red Sea; and, by order of the Admiralty, Lieutenant 


THE ATLANTIC TELEGRAPH. 479 


Dayman, of H.B.M. ship “Cyclops,” ran last year a beauti- cnaprer 
ful line of deep-sea soundings along the telegraphic plateau. 

By that excellent work Lieutenant Dayman confirmed Ae 

what, in February 1854, I had told Professor Morse con- t2o. sea 


cerning this plateau." soundings 


When the deep-sea soundings came to be studied under 
the microscope, it was discovered that many of these little 
mites of shells still retained in them the fleshy parts of 
their inhabitants ! 

This circumstance of shells with fleshy matter in them 
from the bottom of the deep sea is one of the most beauti- 
ful and suggestive facts that this new system of deep-sea 
soundings has revealed. 

We roam with it through the realms of conjecture, go Thess 
a step further in this direction, and fancy that the sea its dead 
embalms its dead—that all the corpses which, with 
weights attached, have been committed to the deep in 
blue water, are now standing on the bottom, their linea- 
ments and features as perfect as they were the day their 
comrades were called to “bury the dead.” ? 

The projectors of the Atlantic Telegraph, having acted [Pc ha 
upon the information derived from these researches con- Gane 
cerning the bottom and bed of the ocean, formed their formed. 
company, and ordered their cable, sought other informa- 
tion from the Observatory. I received, in March 1857, 


1 Vide Plate XI., now (1859) corrected accordingly. 

* When a person dies on board of a man-of-war, and is to be buried at sea, his 
body is sewed up in his hammock, with one or two cannon-balls secured to his 
feet. When it is ready for the burial, it is placed on a plank at the gangway, 
and all hands are mustered on deck by the boatswain’s call to ‘‘ bury the dead.” 
After reading the burial service, the plank is tilted, and the body slides off, feet 
foremost, into the sea. In this position the body sinks, in this position it 
reaches the hottom, and in this position it may remain, beyond the reach of 
aecay, a perfect human form for ages. 


480 THE PHYSICAL GEOGRAPHY OF THE SEA. 


carter a letter from Cyrus W. Field, asking, in behalf of the 
“company, for the best route and time for laying the cable. 


Best route 
and time 
for laying 
the cable. 


Considering the practical difficulties of actually steering 
along an are of such a great circle as that which passes 
through the ends of the Atlantic cable, Professor Hub- 
bard was requested to compute the perimeter of a polygon, 
described in such a manner that every side between 
Valentia and Trinity Bay should be trisected by the are 
of the great circle between the two ends of the cable, and 
that a ship in steering along this perimeter should, to 
pass from one side to the next, have to change her course 
but the qnarter of a point. Thus a polygonal route was 
given by which each ship, by increasing her great circle 
distance only three hundred and fifty fathoms, and chang- 
ing her course only six times after joining cables, would 
be enabled to reach her port by steering straight courses. 
Lieutenant Aulick projected in duplicate the sides of this 
polygon on charts, which were sent to the company for 
the paying-out vessels to steer by. 
Esvorions Lieutenant Bennett was called on to assist in the in- 
tions, vestigations necessary to enable me to answer the ques- 
ticn as to the best time for laying the cable. For this the 
results of 260,000 days of observation at sea were con- 
sulted, and, after a laborious investigation, the company 
was informed of the result, which was, that the “ most pro- 
Bore: pitious time for their undertaking was the last of July and 
the first of August,” and that “the steamer with the 
western end of the telegraph cord on board would be less 
liable than the other to encounter a gale.” This proved 


> 


true; for the “Agamemnon” came near losing her end of 
the cable, owing to the violence of wind and waves, while 


- the “Niagara” was sailing with the western end in smooth 


THE ATLANTIC TELEGRAPH. 481 


water and a tranquil sea; and it also turned out that carrer 
“between the 20th of July and 10th of August” was the 2" 
time which proved the best. 

The attempt again to span the Atlantic Ocean § 1026 
with an electrical cord will probably be made in the (ery 
summer of 1860. Let us consider the true nature of the ae 
Neptunian difficulties in the way; for it appears to me {0 )3 
that the obstacles which the sea opposed to the attempt 
of 1857-8 are not rightly appreciated. 


I leave out of view, at present, all questions re- § 1027 


. . syite Neptunian 
lating to the electrical conditions of the problem, and gieuues 
in the 


address myself exclusively to the Neptunian difficulties 
with which the projectors of any line of telegraph across 
the Atlantic Ocean will have to contend; for, had the 
true nature and extent of these difficulties been properly 
considered by the London Company, I have no doubt but 
that the Atlantic Telegraph wouid have, at this day, been 
in successful operation. 


way. 


The facts which our system of deep-sea soundings has 
brought to light concerning the status of the deep sea are 
such that, when properly considered by the hydro-tele- 
eraphic engineer, will render lines of submarine telegraphs 
as cheap, if not cheaper, than our overland lines are. A 
full account has been given of these discoveries in this 
work, and in Vol. I., 8th edition, -“ Maury’s Sailing 
Directions.” 

In repeating these facts here, and the results derived Sat 
therefrom, let us, in the first place, confine our attention at theboe 
to “blue water.” It is an established fact that there is aeep sea 
no running water at the bottom of the deep sea. The 
agents which disturb the equilibrium of the sea, giving 
violence to its waves and force to its currents, all reside 


3] 


CHAPTER 
XXI. 


—— 


No change 
of tem- 
perature 
in the 
depths of 
the ocean. 


Disturb- 
ance by 
the winds 
only at the 
surface. 


Stillness 
at the bot- 
tom. 


482 THE PHYSICAL GEOGRAPHY OF THE SEA. 


near or above its surface; none of them have their home 
in its depths. These agents are its inhabitants, the 
moon, the winds, evaporation and precipitation, with 
changes of temperature—such as heating here, and cool- 
ing there. 

The rays of the sun cannot penetrate into the depths 
of the ocean, and radiation cannot take place thence ; 
consequently, the change of the temperature in the 
depths of the sea, from summer to winter, and from 
winter to summer, must be almost, if not entirely, unap- 
preciable. This is a generally admitted fact. 

The winds take up water from the surface, and not 
from the depth, and in so doing they disturb the equili- 
brium of the water at the top, not the equilibrium of the 
water at the bottom; by evaporation, the water on top 
becomes salter and heavier than it was before ; the vapour 
thus taken up is condensed into rain and precipitated on 
other parts of the sea, thus both raising the sea-level, and 
making the surface water lighter and less salt than it was 
before. Thus we have the genesis of horizontal circula- 
tion, or an interchange of water called currents. If, by 
the process of evaporation, the surface water becomes so 
salt as to be heavier than the water at the bottom, the 
water at the bottom and the water at the top will 
change places. This may give rise to a vertical circula- 
tion, but one so feeble that it cannot be felt by even the 
tiny little shells which strew the bed of the ocean, and 
which lie there as lightly as gossamer under the dew of 
the morning; practically, therefore, the water at the 
bottom is still. 

It is also generally admitted that the waves, even in 
their most angry moods, are incapable of reaching far 


THE ATLANTIC TELEGRAPH. 483 


down in the sea, or of disturbing the quiet and repose cnaprer 
which reign in its depths. an 

In short, there is reason to believe that the bottom of me waves 
the deep sea is everywhere protected from the violence of cant Ietse 
its waves, the abrading action of its currents, and the a 
rage of the forces which are ever at play on its surface 
by a cushion of still water. 

The grounds for this belief are contained in these Grounas 
pages; but, to recapitulate briefly, they are afforded by beliet 
these circumstances: everywhere, whencesoever specimens 
of bottom have been obtained by the deep-sea plummet, 
they have been found to consist of the untriturated re- 
mains of the microscopic organisms of the sea. Some of 
these have the flesh of the little creature still in them. 

Now these feculences of the sea, as the remains of its 
microscopic inhabitants may be called, are relatively as 
light in the water as motes in the air; and, if the 
bottom of the sea were scoured by its currents, those sew Themicro- 


. e F A scopic in- 

motes would be swept away into drifts like snow, or into habitants 
* . fthe dee 

dunes like sand; they would be scratched, their sharp ae ieee 


quiet and 


corners and the edges would be broken off and rounded. gninjurea 
Moreover, were they drifted about, then sand and other 
scourings of the ocean would be found mixed with them. 

But not so; the specimens brought up from the deep sea 

show no such mixture, and the infusoria thence bear no 

marks of abrasion upon even their most delicate parts. 
Indeed, some of them are so fresh, still having the meat 

of the animal in them, that Professor Ehrenberg, of the Biotie 
Berlin, with others of the Biotic school, maintains that See 
these shells live at the bottom of the deep sea, whence the sa tes 
sounding-rod recovered them. The anti-Biotics, on the 
eontrary, maintain that they live and die at or near the 


484 THE PHYSICAL GEOGRAPHY OF THE SEA. 


cuapTer Surface, and are buried on the bottom and bed of the 
= ocean; that the antiseptic properties of sea-water tend to 
prevent decay in the first instance, and as the dead 
animalculz continue to sink, the pressure of the superin- 
cumbent water prevents chemical decomposition ; and, 
consequently, they of this school hold, and rightly hold, 
I think, that so far from admitting that any of the 
abrading forces of water, which are so familiar to us, are 
harboured in the depths of the ocean, or that they can 
Trehand find room for play there, the hand of decay itself becomes, 
ae when stretched forth in the chambers of the deep, so 
ee palsied as scarcely to be able to make itself felt, even 
upon the most perishable things, when once lodged on the 
bottom of the deep sea. 
Amountof The pressure on the telegraphic plateau varies from 
onthe te. 200° to 300 atmospheres; that is, from 430,000 to 
ee 650,000 Ibs. the square foot. Chemical forces may be 
measured, and consequently overcome by pressure, for the 
gases generated by chemical decomposition are themselves 
capable, so the chemists tell us, of exerting in the process 
of that decomposition only so much pressure; hence, if 
we subject them to a greater pressure, they cannot 
separate, and decomposition cannot take place. 
eee In proof of this, I refer to a recent discovery of Ehren- 
eentais- berg. In the specimens obtained at a great depth from 
See Fae Mediterranean, that celebrated microscopist has dis- 
tinctly recognised fresh-water cells with meat in them. 
From this beautiful little fact we may infer that the very 
volatile gases which enter into composition for the for- 
mation of the fleshy parts of marine animalculee are sub- 
jected to such a pressure upon the deep bed of the ocean 


that they cannot separate. If this inference be correct, 


id 


THE ATLANTIC TELEGRAPH. 485 


and it doubtless is, may we not proceed a step further, cuarrer 
and conclude with reason, that with the pressure of the = 
deep sea upon it, the gutta-percha used for insulating 
submarine wires becomes impervious to decay ? 

With a due appreciation of these facts and circum- 
stances, we are now prepared for the question which in- 
volves most of the Neptunian difficulties with which the 
Atlantic Telegraph Company has been contending with 
their cable; and the question, such being the facts, may 
be thus stated :—Is not any cable that is heavy enough Question 
to sink, strong enough to lie on the bottom of the deep scree etiot 
sea? If yea, then, it may be asked, why have any see 
Atlantic “cable” at all?—why serve gutta-percha cords 
for the deep sea with iron wire at all? I am not speak- 
ing of the shore ends, where the water is shallow, where 
abrading forces do work, and where the iron service’ 7s 
required ; but, as I said, my remarks relate to the deep 
sea, and I speak of the cable for that. 

Of what use to the cable, it may be again asked, was wiat was 


the use of 
t 


that iron coat of mail in which the insulated conductor the iron 


was incased? Was it to make the cable sink? Why in 
the Company found the cable so heavy when they began ‘°° 
to pay it out into the deep sea that they were constrained 

to postpone the undertaking from 1857 to 1858, that 
they might tax the ingenuity of the world for brakes 

and paying-out machinery that would prevent the cable 
from parting by its own weight when running out 

in deep water. Without the iron coating it was heavy 
enough to sink, and if it were not so, a little larger 
conducting wire would have made it so, without any 
wyury, I apprehend, to the electrical capacity of the 
cord, 


CHAPTER 
xxi. 


A substi- 
tute for 
buoys pro- 
posed. 


Inquiries 
as to the 
use of the 
iron wrap- 
ping for 
the cable. 


486 THE PHYSICAL GEOGRAPHY OF THE SEA, 


Many have proposed buoys for the cable. 

What a simple substitute for buoys would it be to 
leave off the coating of iron wire? Had that been left 
off the cable, there would have been no need of brakes, 
and of much other machinery rendered necessary by the 
cumbrous coat of mail. 

Bearing in mind the quiet which reigns at the bottom 
of the deep sea; that the bed of the ocean is protected 
from the abrading action of its currents by a cushion of 
still water; that there is no running water down there; 
and that the pressure is such as to obstruct, if not for 
ever to prevent, the decomposition of all animal and 
vegetable matter when once lodged there, let us inquire 
a little more minutely as to the use of that iron wrapping 
for the deep-sea cable. 

It was not to protect the cable from abrasion after it 
was lodged on the bottom, for we have discovered that 
there are no abrading forces there to fret it. 

It could not have been to keep the cable down, for 
we have seen that the slightest dregs that float in the 
water are, when allowed to settle on the bottom of 
the deep sea, heavy enough and stout enough to remain 
there. 

It could not have been on the score of economy, for 
the cost of the cable must have been nearly, if not quite 
doubled on account of the iron wrapping. 

The wrapping of iron wire without does not, I imagine, 
tend to improve the conducting powers of the copper 
wire within; and—besides the cost and the difficulty of 
manipulation, owing to increase of both size and weight 
which this iron wrapping gives the cable—that increased 
size and weight had something to do with the electrical 


THE ATLANTIC TELEGRAPH. 487 


_ difficulties of the cable. What the real nature of these cuarter 
difficulties is must be matter of conjecture, but the con- = 


. . ° e « Fo tion 
jecture which seems to be most plausible is one of this o¢ aa’ 


sort: the conducting wire is a strand of seven copper “”* 
threads twisted together; this strand is then coated with 
gutta-percha, making a straight cord about the size of a 
lady’s finger; this cord is then served with eighteen 
strands of iron wire, consisting of seven threads each, 
wrapped spirally about it. Now, in the process of paying 
out in the deep sea, and in holding back, the strain of 
the two or three thousand pounds which was brought to 
bear upon the cable, in order to prevent it from running 
out too fast, was first borne principally by the straight 
cord, consisting of gutta-percha and the conducting wires, 
rather than by the spirally-laid iron wires. 
To illustrate this proposition, namely, that the strain Te strain 


was borne 


was brought to bear upon the straight centre-piece OF principally 


. . ° . by the 
heart, as the conducting wire and its coating of gutta- Senin 


centre- 


percha may be called, rather than the spirally-served iron jicce or 


wire, it is only necessary to refer to rigging on board °"* 
ship that is laid up with a heart-piece or centre strand. 
The strands of the rope, like those of the iron wire, are 
laid spirally about the heart, and when the rope has been 
subjected to a strain, “ Jack,’ to use his own language, 
always finds “the life gone out of the heart.” Certainly 
a spirally-laid rope will stretch more than the straight 
centre-piece about which it is so laid. Such was the 
strain brought by the brakes upon the cable on board 
the “Niagara,” says an eye-witness, that “large quantities 
of tar are pressed out of the cable as it enters and leaves the 
machine, and falls into tubs which are left near the machine 
for its reception. Of this stuff a couple of ordinary-sized 


488 THE PHYSICAL GEOGRAPHY OF THE SEA. 


cuarter barrelfuls are collected each day and thrown over- 
> (poard 7 
The con- Here was force enough to impair insulation by stretch- 
ee re- Ing the gutta-percha, or to injure conducting powers by 
setching Stretchin g or breaking the threads of the conducting wire; 
mgthe f0r, as I said, when the “Niagara” and “Agamemnon” were 
inewire, Paying out this cable last summer in the deep sea, and 
when the brakes were holding back with a strain of 2000 
or 38000 lbs. on the cable, the heart suffered first. The 
gutta-percha would outstretch the copper, and then the 
seven small copper threads composing the conducting 
wire were attacked in detail, and thus the strength of the 
conducting wire was often tried without any perceptible 
giving way. It was impossible to have the strain to 
come upon all the threads of the conductor exactly alike; 
probably, therefore, first one parted and then another, so 
that in the whole distance each one of the seven may 
have parted many times; sometimes one alone, and 
sometimes several, perhaps all, or all but one or two at 
the same place ; for the parting of any one facilitated the 
parting of the rest, and all in the same place. One 
conducting wire would have been better, both in an 


economical, electrical, mechanical, and Neptunian point 


of view. 
One con- At first the fractured surfaces, with their crystalline 
ducting A 


wire better points, were, it may be supposed, bright, and the galvanic 
eae current could leap the little chasms with comparative 
facility ; but use tarnished them, and the leaps became 
more and more deficient. Hence the passage of intelli- 


gible messages at first, and their gradual cessation, and 


1 Mullaly’s ‘ Telegraph Cable,’ page 264. 


THE ATLANTIC TELEGRAPH. 489 


the subsequent failure of the cable to give any signs of cuarrex 


. XXxI. 
life. 
: : : f : ., Conjecture 
This, however, is, as I said, mere matter of conjecture; shout the 


but it is the most plausible answer that I have heard to (8° "1Y 


the question, “ Why has the cable stopped working?” BLonHed 
working. 
The first step, therefore, toward success in the estab- § 1028 
lishment of submarine lines of telegraph across oceans ae 
is to get rid of the idea of iron ropes and great cables for cess te set 


the deep sea—limit these to shallow water; to divert ee ui 
ingenuity from brakes and buoys, and to direct it to 
cords that will require neither. 

But some will say that the heat in a ship’s hold is 
often such as to melt the gutta-percha, and therefore an 
iron wrapping, to hold it together, and so preserve the 
insulation, is, necessary. 

The Rogers cord is a complete answer to this objection. The Rog- 
After insulation, he braids the conducting wire whip-cord coe 
fashion with bobbin or twine, and then protects the whole uae 
with a pigment, gum or cement, which shields the gutta- 
percha, securing it against chafes, bruises, melting, &c., 
and still leaves the cord so small and manipulable that 
one ship may carry the whole of it, and “pay and go” 
with it across the Atlantic as though she were making 
an ordinary passage. . 

The specific gravity of this Rogers cord is such as to Its specif 
carry it down at the rate of only a mile or two an hour. pee 
Now, it is evident that pieces of such a cord, if cut into 
lengths of ten miles long, for instance, and thrown into 
the sea, would find their way to the bottom as readily as 
pieces of one mile or of a few fathoms in length would ; 
and since, at the greatest speed of the paying-out vessel 


not more than about ten miles of this cord will, at any 


490 THE PHYSICAL GEOGRAPHY OF THE SEA. 


carrer one time, be between the stern of the vessel and the bot~ 
** tom of the sea, the feat of laying it in lengths of ten miles 

may be practically accomplished by an artifice, and that 
artifice consists in paying out the cord with slack enough 
in every ten miles of it to feed the currents and to 
spare. 

ee The common operation of “heaving the log” may be 

Rogers referred to in illustration of the manner in which the 

welaaed Rogers cord may be laid. In heaving the log, a certain 
quantity of what is called “stray line,” or slack, is always 
paid out. This new cord is not larger than a common 
log line; and the line between Varna and Balaklava, 
which worked so well in the Black Sea, was, I have 
understood, paid out by hand. It was simply a copper 
wire insulated by gutta-percha, and without any other 
covering. If such a wire could be laid in the Black 
Sea, one could be laid in the deep sea as well, for 
there is reason to believe that the currents of the 
ocean do not extend beyond a few hundred fathoms in 
its depths. 

Amountof ‘There seems to be a sort of general impression that 

eauired the amount of slack cable required to feed the currents 

heres of the sea is very considerable. A little reflection will 
show that this is not the case, especially along the tele- 
graphic plateau. 

The current which requires the greatest proportion of 
slack is one which sweeps across the cable at right 
angles; whereas the great circle along which the Atlantic 
Cable was laid crosses the Gulf-Stream so obliquely that 
a vessel running along from Newfoundland to Ireland 
may be considered as running with that stream for much 


of the way. 


THE ATLANTIC TELEGRAPH. 491 


The current along the telegraphic plateau seldom ex- cuapren 
. XXI. 
ceeds two knots an hour; it rarely amounts to that. 
But, to present the strongest case against the view I am re 
: E rent along 
advocating, let us suppose that the current runs all the po ya2 
way across at the rate of two knots, and at right angles #7" 


ies 
to the cable, and that a vessel with the proper length can 
the Rogers cord on board were to set of, to “pay and 
go” with it from Newfoundland to Ireland. The cord, rime 
being paid over with 10 per cent. of slack, is heavy eel 
enough to sink at the rate of two miles an hour; the” *"“"* 
current, let it be supposed, descends to the maximum 
depth of half a mile; any given part of the cord, there- 
fore, as it goes out and sinks at the rate of two miles an 
hour, occupies fifteen minutes in sinking the first half 
mile. During these fifteen minutes only it is exposed 
to the current, by which it is swept half a mile to the 
right or left of the track of the ship; then reaching the 
still water below, it settles down through it until it 
reaches bottom. 

Thus, in the case supposed, the cord would not le in 
a zigzag, but more in a straight line all the way across, 
and only half a mile to the right or left of the path act- 
ually made by the keel of the ship. The difference in 
distance by such a path and such a line would be prac- 
tically inappreciable, and yet the case supposed is an 
exaggeration of the case that is actually presented. For 
a part, if not for the whole distance, there is an under 
current which would bring the cable back toward the 
wake of the ship, thus tending to counteract the effect of 
the upper current in sweeping it off. 

In confirmation of these views as to the existence of a 
cushion of still water at the bottom, I bring in for furthe 


CHAPTER 
XXI. 


A cushion 
of still 
water at 
the bot- 
tom of the 
ocean. 


No doubt 
of the ulti- 
mate suc- 
cess of the 
Atlantic 
Telegraph. 


492 THE PHYSICAT, GEOGRAPHY OF THE SEA, 


evidence the testimony afforded by Commander Dayman, 
R.N., while running his line of deep-sea soundings along 
the telegraphic plateau, in H. B. M.S. Cyclops. On one 
occasion he hauled up from the bottom a coil of two 
hundred fathoms of deep-sea line. It had been laid at 
the bottom round and round in a coil with as much 
regularity as it could have been coiled on deck by hand, 
thus showing either that there was no current there at 
all, or that the upper and the under currents so nearly 
counteracted each other that the line passed perpendicu- 
larly through the still water. 

The tiny nautilus rides out the hurricane, and weathers 
storms in which the stoutest men-of-war have foundered; 
and, in order to make progress in submarine telegraphy, 
we must proceed upon the principle that a slack line vm 
the sea will hold longer than a taut cable, for the forces 
of its waves and its currents are not to be overcome by 
such powers of resistance as human fabrics have the 
strength to offer. | 

I have no doubt whatever as to the ultimate success 
of a telegraph across the Atlantic. Indeed, the only 
limit to our power to establish at pleasure lines of sub- 
marine telegraph is the limit, if any, which Nature herself 
may have imposed upon the galvanic current. The sea 
offers no obstructions on account of its depths or its 
currents to lines of any length. 

A line with an unbroken conducting wire across the 
Atlantic or Pacific is as practicable as one across the 
Alps or the Andes. In the long run, and mile for mile, 
I do not think there would be much, if any, difference as 
to cost between the transmontane and the submarine 
line. 


THE ATLANTIC TELEGRAPH. 493 


The veal question for future projectors of lines of cuarter 
xXi. 


submarine telegraph is not how deep, or how boister- —_ 
ous, or how wide the sea is, but what are the electrical $ 1029 


The real 


linvits to the length of submarine lines." question 


for projec- 
tors of 
lines of 


1 See ‘ Journal of the Royal Dublin Society,’ Nos. XII and XIII.: ‘‘ Letter submarine 
to John Locke, Esq., on the Atlantic Telegraph Cable: Causes of Failure and telegraphs 
Probabilities of ultimate Success, by M. F. Maury.” Read Friday evening, 

January 28, 1859. 


Observatory, May 1859. 


PEATE: 


Calms of Cancer. 


Calms of Capricorn 


DIAGRAM OF THE WINDS. 


— vv 
wrt 
a 
f 
= 
— 
ALA 
» = 
‘ 


oe oP e 


TEE ATE, AL : PEATE HT. 


BROOKE'S DEEP-SEA SOUNDING APPARATUS 


a 


. 
~ ere 


ISOTHERMAL CHART or tut ATLANTIC OCEAN 


for March and September. 


} es 
oye 


es 


z |_PoRTUGaL 7, ee ef SAS 
j zi bMEDITER, 0) 
Le etn. 


| oS 
Azores 
oe 


aaa ; ria 6 
Madeira » | ° rae | 
j | | 


Canary (I? -,|- 


aie | | 
= 
RT. 


Pane SON BA, 
= Reals vt 


| Gulf of Guimea } 


Cape f 
‘aE Good Tope ti 


— September 


__ | 20°North. 


ae ar | 


} mi 


| | 362] 
TRUTH ORT] TAD AWD TIT | ARTA) TRY WAT fe 
| | 


} OA Ud UA) IN 
jit | | 


| 

1128 

PSI 
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TRCN RT OTN ROTA 
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South 


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Mi 


S.S.W. 
| 


_S.W. || 


_W.S.W. 


_ West| 


Ww. | 


NNW. | (as ae a | 


NW. | | ne | 
| | 
cule | 


168 |o0e _|eor [exo pee [r 


76 | | | ‘North 


+ te — t | 4 
il| May June)July | Aug. Oct.iNov. 


10°North 


ee [Real ] ; 
||Dee! Jan. Feb. Mardhdpril July\Aug. ; 
ea FT Tf 5 aii S See eal aics 


Wale be be 


LN.E. | 
ok te NNR) 
axe IST ed wo 
Seer VL LN LRG 
i 


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Ir} 


: peso peE UK San Se FRC fF — 


tM lial 


tee I en 


| | | | 1am 
TT RT TTA AOE CTT 
| Uk | jm i mm | | 


TTT A TACT CT 1} 
| |W hel | wm | mt 


| | | | 
RAO SORTS ae Ta a FTATT- 
| TRUTW TO td 00 Ww |v | 


| 124 | | WJ l 
a a aL ay 


ts 5 ‘North 
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A 
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GULF STREAM AND DRIFT. 


EXPLANATION. 

4 a The place of the San Francisco alter the wreck Dec. 26% 
0 Where she was abandoned Jan. 4h 

ab Computed linats of Drift 

ce Where the searching vessel was directed to loole tor her 
| wyz The hot streaks of Fig. A. 
| — Direction of low and Dyitt 
i i), Flow, not steady in any direction. 


| 


f 
| 
} 
| 
| 


sage. SAO <= 
WSMNe,, = Tite Musles 
gaa taal Say, —abboe 
4 |, = 


atu 
wut 


he witty, 


ug 


Fig.A. Thermal Section of the Gulf Stream. 
n— Mean of 0,5,10,20 & 30 Fath? — s Mean of 200, 500 &-400 Fath? 
50, 70,100 &150 _ — . J00 Fath? 


} 


90 50 


—— 


eG 


<9 
i 


+ 


GEOLOGICAL AGENCY OF THE WINDS. 


Teopie of |C 


Explanation. Note. 


ri aly cesta Wimatahe ited The Wind , represented ty the Arrows in the Southern Hemisphere ax Monsoons 


feed: Mississippi wi [ns , 3 , . y 
That veds the Mississippi with rains and) Tradas, ix supposed, whan it mocts the HE. trades, to rise up and. Flow to 
ts supposed to be taken up: The Hands | 3 


inting to the direction to which | the Northward and Eastward as an upper current, until Uh passes the NE. trade 
pointing to the direction to whic: 


| 0 7 , r uce as the prevailing 8.Wowind of the 
| tt iv wafted. The Waht shading A shows f j wind region. It ten appears on the surface a P 7 


|where it is supposed to pass as an upper iS - : extra-tropical regions of the Northern Hemisphere, as per the Arrows to the 


current ; and. the shading C, where it is North of the Tropte of Cancer un Europe and Asia, 


preetpitated . The Arrows in the North : The feathered Arrows in the North extra-tropical region i the 
Pacific show where the vapour that supplies : 2, coer supposed route of the air (SW. Passage Winds | in that region, which has 
Southern Chili and Western Patagonia | passed over South America as the SE. trade winds and the monsoons ; and 
with rains, is supposed to be taken up; the untvathered Arrows in the same region are intended to represent the route 


and the Arrows in the South Pacific show of the SE. trades and monsoons of Africa, as indicated bu similar Arrows. 


the direction of the surface winds which ; : 
waft this vapour after it has crossed the 


shading B, as an upper current. 


1 . . TNELSON,& SONS, LONDON, EDINBURGH & NEW YORK. P| 

‘te - . : : ” 

m4 —_ , we } 
A A in ie a - — =. \ P - = 


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a LLL LL DE © 6p = age ee 


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a ae ia = - os “ 7 = ° —_— wa 
ae. a © i 
ROUTES 


EXPLANATION 


4 
LP North Bast Trades 


. ~ South Bast Trades 


South Bast & South West Monsoons 


 SeRLARD 
L- 


NO RT 


eee B 


B ais Anny 5, 
bs 
Bia 


> 
< 
s 
* 


NE ZUELA 


6[LANAD Am « 


wADon 


Peas AS ; sleeved | 


<b Routes and average passage in daus Place of Doldrums for 


<a Fair Winds 2 iia) Desert March dus 
an Head Winds Intand Basin September 


SEA DRIFT AND WHALES; on which the movements of the Sea as indicated by the THERMOMETER are shevn. 


EXPLANATION 


— Folar limits of Sperm Whale ground 
—— — Equatorial limits of Right Whale ground. 


“4 
A (xups ox's 
- 


BAY 


Ss | 


* 


lEniand |Basin 
| 


WTICMAM, 
val 


Wie Me 
Nd 
Aaja at “%)) 
el ae 
. 


ae 


esse eee ee ee ee eee eee 


30 


Ss. LOS) iON, EDINBURGH & NEW YCRK. 


y., 6. 2@ 


hein pale has pee 
inte Gee Panter ghee 


i 7 ‘ ry 


PLATE N. 


20} 


5 
“+. 
A 

| 

| 

£ 
al 


‘Warcella” 


+ Shift From 
pi S.to WV. Sudden 


SW to 8 


1130 p.m, 
7h 


B. 28.63% 
eS NE Marton 
a 


Se 


J Uh.a.m 


AUGUST AND 


SEPTEMBER HURRICANE OF 1846. 


4 am.5.5.¥. to NNW 
1 


2 29 Sept. 1846 


“1 oon 


ft ff aim, SSW, ta SB. 


1 
Mary Ann 
2”, od 
ie 
Noon => 
<2) 


SW.to Woam, 4 


(<= = +" oe ae a nnn ne a | | en 
50 ag 438 a7 46 45 44 45 Creole YW vA 40 39 55 oh 
45 ii <<<." ¢ ~ 2 ea =; T 
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1yf 4 yo 
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Marseilles 


| In the later 8.2. by 3, to comply with | the 


| 
| 
| 


The course of the Starm trom the Beazeillero’ 
to the "Marion." is Tt. by N. From. the Marion. 
NE. ta 2. In the former course the chkinge of 
wind should be trom S.bu E. towards the West, 


| 
tao 


— leo 


Ss aaa Q Whirlwind Diagram . 
So The unteathered Arrow to the Lett of thesteathered. 
‘Nay AZORES pointing Northerly indicates that the witd should 
Ss 7 ai have changed to the Lett. * 
a ° Mary pAnin TL, hh. stand tov Lhunder, Lightning and Rain 
¥ ay) * ae a! 7 Tf, tor Hurricane. iN 
U N ] N Y + Lo comply with the Whirlwind Diagram. i 
1o 
Be, ke MAPEIRA _ & 
pues le haus ~ 31 
: 585 AM og lee ! * ag1° | 
is sil i 1 x ~Kathleen 30 
50 RoN eae ain ASI 
RY \ tN 7 49:0 CANARY |I? 
| . Orbit \30 Ne « [30-0 Sah L 
Ee alles | > i ae o es 
Shes \yGlean g The White Tine jd the Tralek is the 
GUL F OF Te a LAs path of miniraun pressure . 
26h — ce aT = 7 WV at the endl of the drrow denote 
nes Z! losephaine the Wind's fofee, La gale, 2 fresh wind, 
"ee |3 moderates 1 light, calm. | 
25's. fe B. for Harometer. 
o , 
BS 
fs 2 
20 =p es t ; al y 
Kirkland. } C! ’ 
a land ee oe PN | a te 
19 Bar. 29-4 eG 4 
ae 
25 Cc el dug Bar. 29 be iE jo | 
2 Bar. 29-3 
IR Gardner 4 — Vi Light 
24h oat y 
’ pares mee ; | 9 
| 9° ee R. f 
28 : 
126 
At 1:30 p.m.B, 29-2 
F. going up very fast to 20-6 
A ‘Rh, ‘Ep eee SSW. Lam, ( a 
IR TEE 5 O T AU) MO BIR, Td! A . 
70 60 50 40 


T.NELSON & SONS, LONDON, EDINBURGH & NEW YORK. 


ao 85 80 
f aie 
Explanation 


less than 1000 Fathams 
from 2000 to 2000 
2000 . 3000 hi 2 
3000. #000 . os xe , : . 
(Bland) more than 4000 e : eae 5 pgeo 
“Ss Banks = S 


Hote, "1208 


} weaa | 
1760, i 
| i 
1520, 1500) 
See UIE Soy Niemen Ser 
1560 | (01500 
| 1570 
1850, | 


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Boston> 3: Se f g ) I eat L rig00 Boars 
‘3 ° ‘ J E { if H 


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New York d , te She | ©2050 


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e1800 


5 AZORES | 
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450° Ss 8 
= 

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28 2500 

2750 


54 G: Charles 


° { pas : y 
“ a £1460 j 5070! : | Straits of Gibraltar, | 
Bf. Hatteras / | = iB ; 2290 a) 


x j 
©1800 MADEIRA 
©2250 
@ ©2080 — 
2500 


22700 


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| 2025 
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WEARS Hea So a J z ‘ 2B i eas %% tA i 2 2560__ S8IR 
6530 ‘ a? aa | = 


~aye, VE RD 8 
OF a “1012 r3 


© i'l 1570 91580 
2460 bes 


| 
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| | 3 i 
| | 


Vertical 


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| 


fi 620 | 


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2000 € Lay) 
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T.NELSON & SONS, LONDON, EDINBURGH & NFW YORK. 


er LL, 


VERTICAL SECTION — NORTH ATLANTIC PLATE XU 


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7 $ | (i Bie f = 


10 W. Longitude 90 60 70 60 50 LO 


PLATE XT 


ATLANTIC. 


‘ORTH AND SOUTH 


IN WN 


STORMS AND RAINS 


Wast Indies not included 


60° 


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T NELSON & SONS, LONDON EDINBURGH & NEW YORK 


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EQUATO 


THUNDER 


South 


Vorth 
South 
South 

South 


caeecnen ten roms) on meena semis esrcnal | 


North 
South 


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