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Immanuel Kant - "The Critique of Practical Reason"

L. Muhlbach - "Joseph II. and His Court"

Myrtle Reed - "Old Rose and Silver"

New Philadelphia Book Publisher Highlights Local Talent
Book and Publishing News from Publishers Newswire(tm)

Looking for Child to be on Cover of a New Book, 'The Model Child'
PHILADELPHIA, Pa. -- The Philadelphia literary world will celebrate the launch of two new players today, April 10th: Kay Square Press, a new publishing company focused on Philadelphia-area artists, their stories, and their art; and Kay Square's first release, 'With the Rich and Mighty: Emlen Etting of Philadelphia' (ISBN: 978-0-9815129-0-7), a critical biography by Kenneth C. Kaleta.

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Books: Equinoctial Regions of America V2

A >> Alexander von Humboldt >> Equinoctial Regions of America V2



Produced by Sue Asscher asschers@bigpond.com




BOHN'S SCIENTIFIC LIBRARY.


HUMBOLDT'S PERSONAL NARRATIVE

VOLUME 2.

PERSONAL NARRATIVE OF TRAVELS TO THE EQUINOCTIAL REGIONS OF AMERICA
DURING THE YEARS 1799-1804

BY

ALEXANDER VON HUMBOLDT AND AIME BONPLAND.

TRANSLATED FROM THE FRENCH OF

ALEXANDER VON HUMBOLDT

AND EDITED BY

THOMASINA ROSS.

IN THREE VOLUMES

VOLUME 2.


LONDON.

GEORGE BELL & SONS.
1907.
LONDON: PORTUGAL ST., LINCOLN'S INN.
CAMBRIDGE: DEIGHTON, BELL AND CO.
NEW YORK: THE MACMILLAN CO.
BOMBAY: A.H. WHEELER AND CO.


***

A tablon, equal to 1849 square toises, contains nearly an acre and
one-fifth: a legal acre has 1344 square toises, and 1.95 legal acre is
equal to one hectare.

A torta weighs three quarters of a pound, and three tortas cost
generally in the province of Caracas one silver rial, or one-eighth of
a piastre.

It is sufficient to mention, that the cubic foot contains 2,985,984
cubic lines.

Foot (old measure of France) about five feet three inches English
measure.



VOLUME 2.


CONTENTS.


CHAPTER 2.16.

LAKE OF TACARIGUA.--HOT SPRINGS OF MARIARA.--TOWN OF NUEVA VALENCIA
DEL REY.--DESCENT TOWARDS THE COASTS OF PORTO CABELLO.


CHAPTER 2.17.

MOUNTAINS WHICH SEPARATE THE VALLEYS OF ARAGUA FROM THE LLANOS OF
CARACAS.--VILLA DE CURA.--PARAPARA.--LLANOS OR STEPPES.--CALABOZO.


CHAPTER 2.18.

SAN FERNANDO DE APURE.--INTERTWININGS AND BIFURCATIONS OF THE RIVERS
APURE AND ARAUCA.--NAVIGATION ON THE RIO APURE.


CHAPTER 2.19.

JUNCTION OF THE APURE AND THE ORINOCO.--MOUNTAINS OF
ENCARAMADA.--URUANA.--BARAGUAN.--CARICHANA.--MOUTH OF THE
META.--ISLAND OF PANUMANA.


CHAPTER 2.20.

THE MOUTH OF THE RIO ANAVENI.--PEAK OF UNIANA.--MISSION OF
ATURES.--CATARACT, OR RAUDAL OF MAPARA.--ISLETS OF SURUPAMANA AND
UIRAPURI.


CHAPTER 2.21.

RAUDAL OF GARCITA.--MAYPURES.--CATARACTS OF QUITUNA.--MOUTH OF THE
VICHADA AND THE ZAMA.--ROCK OF ARICAGUA.--SIQUITA.


CHAPTER 2.22.

SAN FERNANDO DE ATABAPO.--SAN BALTHASAR.--THE RIVERS TEMI AND
TUAMINI.--JAVITA.--PORTAGE FROM THE TUAMINI TO THE RIO NEGRO.


CHAPTER 2.23.

THE RIO NEGRO.--BOUNDARIES OF BRAZIL.--THE CASSIQUIARE.--BIFURCATION
OF THE ORINOCO.


CHAPTER 2.24.

THE UPPER ORINOCO, FROM THE ESMERALDA TO THE CONFLUENCE OF THE
GUAVIARE.--SECOND PASSAGE ACROSS THE CATARACTS OF ATURES AND
MAYPURES.--THE LOWER ORINOCO, BETWEEN THE MOUTH OF THE RIO APURE, AND
ANGOSTURA THE CAPITAL OF SPANISH GUIANA.


***

PERSONAL NARRATIVE OF A JOURNEY TO THE EQUINOCTIAL REGIONS OF THE NEW
CONTINENT.

VOLUME 2.


CHAPTER 2.16.

LAKE OF TACARIGUA.
HOT SPRINGS OF MARIARA.
TOWN OF NUEVA VALENCIA DEL REY.
DESCENT TOWARDS THE COASTS OF PORTO CABELLO.

The valleys of Aragua form a narrow basin between granitic and
calcareous mountains of unequal height. On the north, they are
separated by the Sierra Mariara from the sea-coast; and towards the
south, the chain of Guacimo and Yusma serves them as a rampart against
the heated air of the steppes. Groups of hills, high enough to
determine the course of the waters, close this basin on the east and
west like transverse dykes. We find these hills between the Tuy and La
Victoria, as well as on the road from Valencia to Nirgua, and at the
mountains of Torito.* (* The lofty mountains of Los Teques, where the
Tuy takes its source, may be looked upon as the eastern boundary of
the valleys of Aragua. The level of the ground continues, in fact, to
rise from La Victoria to the Hacienda de Tuy; but the river Tuy,
turning southward in the direction of the sierras of Guairaima and
Tiara has found an issue on the east; and it is more natural to
consider as the limits of the basin of Aragua a line drawn through the
sources of the streams flowing into the lake of Valencia. The charts
and sections I have traced of the road from Caracas to Nueva Valencia,
and from Porto Cabello to Villa de Cura, exhibit the whole of these
geological relations.) From this extraordinary configuration of the
land, the little rivers of the valleys of Aragua form a peculiar
system, and direct their course towards a basin closed on all sides.
These rivers do not bear their waters to the ocean; they are collected
in a lake; and subject to the peculiar influence of evaporation, they
lose themselves, if we may use the expression, in the atmosphere. On
the existence of rivers and lakes, the fertility of the soil and the
produce of cultivation in these valleys depend. The aspect of the
spot, and the experience of half a century, have proved that the level
of the waters is not invariable; the waste by evaporation, and the
increase from the waters running into the lake, do not uninterruptedly
balance each other. The lake being elevated one thousand feet above
the neighbouring steppes of Calabozo, and one thousand three hundred
and thirty-two feet above the level of the ocean, it has been
suspected that there are subterranean communications and filtrations.
The appearance of new islands, and the gradual retreat of the waters,
have led to the belief that the lake may perhaps, in time, become
entirely dry. An assemblage of physical circumstances so remarkable
was well fitted to fix my attention on those valleys where the wild
beauty of nature is embellished by agricultural industry, and the arts
of rising civilization.

The lake of Valencia, called Tacarigua by the Indians, exceeds in
magnitude the lake of Neufchatel in Switzerland; but its general form
has more resemblance to the lake of Geneva, which is nearly at the
same height above the level of the sea. As the slope of the ground in
the valleys of Aragua tends towards the south and the west, that part
of the basin still covered with water is the nearest to the southern
chain of the mountains of Guigue, of Yusma, and of Guacimo, which
stretch towards the high savannahs of Ocumare. The opposite banks of
the lake of Valencia display a singular contrast; those on the south
are desert, and almost uninhabited, and a screen of high mountains
gives them a gloomy and monotonous aspect. The northern shore on the
contrary, is cheerful, pastoral, and decked with the rich cultivation
of the sugar-cane, coffee-tree, and cotton. Paths bordered with
cestrums, azedaracs, and other shrubs always in flower, cross the
plain, and join the scattered farms. Every house is surrounded by
clumps of trees. The ceiba with its large yellow flowers* (* Carnes
tollendas, Bombax hibiscifolius.) gives a peculiar character to the
landscape, mingling its branches with those of the purple erythrina.
This mixture of vivid vegetable colours contrasts finely with the
uniform tint of an unclouded sky. In the season of drought, where the
burning soil is covered with an undulating vapour, artificial
irrigations preserve verdure and promote fertility. Here and there the
granite rock pierces through the cultivated ground. Enormous stony
masses rise abruptly in the midst of the valley. Bare and forked, they
nourish a few succulent plants, which prepare mould for future ages.
Often on the summit of these lonely hills may be seen a fig-tree or a
clusia with fleshy leaves, which has fixed its roots in the rock, and
towers over the landscape. With their dead and withered branches,
these trees look like signals erected on a steep cliff. The form of
these mounts unfolds the secret of their ancient origin; for when the
whole of this valley was filled with water, and the waves beat at the
foot of the peaks of Mariara (the Devil's Nook* (* El Rincon del
Diablo.)) and the chain of the coast, these rocky hills were shoals or
islets.

These features of a rich landscape, these contrasts between the two
banks of the lake of Valencia, often reminded me of the Pays de Vaud,
where the soil, everywhere cultivated, and everywhere fertile, offers
the husbandman, the shepherd, and the vine-dresser, the secure fruit
of their labours, while, on the opposite side, Chablais presents only
a mountainous and half-desert country. In these distant climes
surrounded by exotic productions, I loved to recall to mind the
enchanting descriptions with which the aspect of the Leman lake and
the rocks of La Meillerie inspired a great writer. Now, while in the
centre of civilized Europe, I endeavour in my turn to paint the scenes
of the New World, I do not imagine I present the reader with clearer
images, or more precise ideas, by comparing our landscapes with those
of the equinoctial regions. It cannot be too often repeated that
nature, in every zone, whether wild or cultivated, smiling or
majestic, has an individual character. The impressions which she
excites are infinitely varied, like the emotions produced by works of
genius, according to the age in which they were conceived, and the
diversity of language from which they in part derive their charm. We
must limit our comparisons merely to dimensions and external form. We
may institute a parallel between the colossal summit of Mont Blanc and
the Himalaya Mountains; the cascades of the Pyrenees and those of the
Cordilleras: but these comparisons, useful with respect to science,
fail to convey an idea of the characteristics of nature in the
temperate and torrid zones. On the banks of a lake, in a vast forest,
at the foot of summits covered with eternal snow, it is not the mere
magnitude of the objects which excites our admiration. That which
speaks to the soul, which causes such profound and varied emotions,
escapes our measurements as it does the forms of language. Those who
feel powerfully the charms of nature cannot venture on comparing one
with another, scenes totally different in character.

But it is not alone the picturesque beauties of the lake of Valencia
that have given celebrity to its banks. This basin presents several
other phenomena, and suggests questions, the solution of which is
interesting alike to physical science and to the well-being of the
inhabitants. What are the causes of the diminution of the waters of
the lake? Is this diminution more rapid now than in former ages? Can
we presume that an equilibrium between the waters flowing in and the
waters lost will be shortly re-established, or may we apprehend that
the lake will entirely disappear?

According to astronomical observations made at La Victoria, Hacienda
de Cura, Nueva Valencia, and Guigue, the length of the lake in its
present state from Cagua to Guayos, is ten leagues, or twenty-eight
thousand eight hundred toises. Its breadth is very unequal. If we
judge from the latitudes of the mouth of the Rio Cura and the village
of Guigue, it nowhere surpasses 2.3 leagues, or six thousand five
hundred toises; most commonly it is but four or five miles. The
dimensions, as deduced from my observations are much less than those
hitherto adopted by the natives. It might be thought that, to form a
precise idea of the progressive diminution of the waters, it would be
sufficient to compare the present dimensions of the lake with those
attributed to it by ancient chroniclers; by Oviedo for instance, in
his History of the Province of Venezuela, published about the year
1723. This writer in his emphatic style, assigns to "this inland sea,
this monstruoso cuerpo de la laguna de Valencia"* (* "Enormous body of
the lake of Valencia."), fourteen leagues in length and six in
breadth. He affirms that at a small distance from the shore the lead
finds no bottom; and that large floating islands cover the surface of
the waters, which are constantly agitated by the winds. No importance
can be attached to estimates which, without being founded on any
measurement, are expressed in leagues (leguas) reckoned in the
colonies at three thousand, five thousand, and six thousand six
hundred and fifty varas.* (* Seamen being the first, and for a long
time the only, persons who introduced into the Spanish colonies any
precise ideas on the astronomical position and distances of places,
the legua nautica of 6650 varas, or of 2854 toises (20 in a degree),
was originally used in Mexico and throughout South America; but this
legua nautica has been gradually reduced to one-half or one-third, on
account of the slowness of travelling across steep mountains, or dry
and burning plains. The common people measure only time directly; and
then, by arbitrary hypotheses, infer from the time the space of ground
travelled over. In the course of my geographical researches, I have
had frequent opportunities of examining the real value of these
leagues, by comparing the itinerary distances between points lying
under the same meridian with the difference of latitudes.) Oviedo, who
must so often have passed over the valleys of Aragua, asserts that the
town of Nueva Valencia del Rey was built in 1555, at the distance of
half a league from the lake; and that the proportion between the
length of the lake and its breadth, is as seven to three. At present,
the town of Valencia is separated from the lake by level ground of
more than two thousand seven hundred toises (which Oviedo would no
doubt have estimated as a space of a league and a half); and the
length of the basin of the lake is to its breadth as 10 to 2.3, or as
7 to 1.6. The appearance of the soil between Valencia and Guigue, the
little hills rising abruptly in the plain east of the Cano de Cambury,
some of which (el Islote and la Isla de la Negra or Caratapona) have
even preserved the name of islands, sufficiently prove that the waters
have retired considerably since the time of Oviedo. With respect to
the change in the general form of the lake, it appears to me
improbable that in the seventeenth century its breadth was nearly the
half of its length. The situation of the granite mountains of Mariara
and of Guigue, the slope of the ground which rises more rapidly
towards the north and south than towards the east and west, are alike
repugnant to this supposition.

In treating the long-discussed question of the diminution of the
waters, I conceive we must distinguish between the different periods
at which the sinking of their level has taken place. Wherever we
examine the valleys of rivers, or the basins of lakes, we see the
ancient shore at great distances. No doubt seems now to be
entertained, that our rivers and lakes have undergone immense
diminutions; but many geological facts remind us also, that these
great changes in the distribution of the waters have preceded all
historical times; and that for many thousand years most lakes have
attained a permanent equilibrium between the produce of the water
flowing in, and that of evaporation and filtration. Whenever we find
this equilibrium broken, it will be well rather to examine whether the
rupture be not owing to causes merely local, and of very recent date,
than to admit an uninterrupted diminution of the water. This reasoning
is conformable to the more circumspect method of modern science. At a
time when the physical history of the world, traced by the genius of
some eloquent writers, borrowed all its charms from the fictions of
imagination, the phenomenon of which we are treating would have been
adduced as a new proof of the contrast these writers sought to
establish between the two continents. To demonstrate that America rose
later than Asia and Europe from the bosom of the waters, the lake of
Tacarigua would have been described as one of those interior basins
which have not yet become dry by the effects of slow and gradual
evaporation. I have no doubt that, in very remote times, the whole
valley, from the foot of the mountains of Cocuyza to those of Torito
and Nirgua, and from La Sierra de Mariara to the chain of Guigue, of
Guacimo, and La Palma, was filled with water. Everywhere the form of
the promontories, and their steep declivities, seem to indicate the
shore of an alpine lake, similar to those of Styria and Tyrol. The
same little helicites, the same valvatae, which now live in the lake
of Valencia, are found in layers of three or four feet thick as far
inland as Turmero and La Concesion near La Victoria. These facts
undoubtedly prove a retreat of the waters; but nothing indicates that
this retreat has continued from a very remote period to our days. The
valleys of Aragua are among the portions of Venezuela most anciently
peopled; and yet there is no mention in Oviedo, or any other old
chronicler, of a sensible diminution of the lake. Must we suppose,
that this phenomenon escaped their observation, at a time when the
Indians far exceeded the white population, and when the banks of the
lake were less inhabited? Within half a century, and particularly
within these thirty years, the natural desiccation of this great basin
has excited general attention. We find vast tracts of land which were
formerly inundated, now dry, and already cultivated with plantains,
sugar-canes, or cotton. Wherever a hut is erected on the bank of the
lake, we see the shore receding from year to year. We discover
islands, which, in consequence of the retreat of the waters, are just
beginning to be joined to the continent, as for instance the rocky
island of Culebra, in the direction of Guigue; other islands already
form promontories, as the Morro, between Guigue and Nueva Valencia,
and La Cabrera, south-east of Mariara; others again are now rising in
the islands themselves like scattered hills. Among these last, so
easily recognised at a distance, some are only a quarter of a mile,
others a league from the present shore. I may cite as the most
remarkable three granite islands, thirty or forty toises high, on the
road from the Hacienda de Cura to Aguas Calientes; and at the western
extremity of the lake, the Serrito de Don Pedro, Islote, and
Caratapona. On visiting two islands entirely surrounded by water, we
found in the midst of brushwood, on small flats (four, six, and even
eight toises height above the surface of the lake,) fine sand mixed
with helicites, anciently deposited by the waters. (Isla de Cura and
Cabo Blanco. The promontory of Cabrera has been connected with the
shore ever since the year 1750 or 1760 by a little valley, which bears
the name of Portachuelo.) In each of these islands may be perceived
the most certain traces of the gradual sinking of the waters. But
still farther (and this accident is regarded by the inhabitants as a
marvellous phenomenon) in 1796 three new islands appeared to the east
of the island Caiguira, in the same direction as the islands Burro,
Otama, and Zorro. These new islands, called by the people Los nuevos
Penones, or Los Aparecidos,* (* Los Nuevos Penones, the New Rocks. Los
Aparecidos, the Unexpectedly-appeared.) form a kind of banks with
surfaces quite flat. They rose, in 1800, more than a foot above the
mean level of the water.

It has already been observed that the lake of Valencia, like the lakes
of the valley of Mexico, forms the centre of a little system of
rivers, none of which have any communication with the ocean. These
rivers, most of which deserve only the name of torrents, or brooks,*
are twelve or fourteen in number. (* The following are their names:
Rios de Aragua, Turmero, Maracay, Tapatapa, Agnes Calientes, Mariara,
Cura, Guacara, Guataparo, Valencia, Cano Grande de Cambury, etc.) The
inhabitants, little acquainted with the effects of evaporation, have
long imagined that the lake has a subterranean outlet, by which a
quantity of water runs out equal to that which flows in by the rivers.
Some suppose that this outlet communicates with grottos, supposed to
be at great depth; others believe that the water flows through an
oblique channel into the basin of the ocean. These bold hypotheses on
the communication between two neighbouring basins have presented
themselves in every zone to the imagination of the ignorant, as well
as to that of the learned; for the latter, without confessing it,
sometimes repeat popular opinions in scientific language. We hear of
subterranean gulfs and outlets in the New World, as on the shores of
the Caspian sea, though the lake of Tacarigua is two hundred and
twenty-two toises higher, and the Caspian sea fifty-four toises lower,
than the sea; and though it is well known, that fluids find the same
level, when they communicate by a lateral channel.

The changes which the destruction of forests, the clearing of plains,
and the cultivation of indigo, have produced within half a century in
the quantity of water flowing in on the one hand, and on the other the
evaporation of the soil, and the dryness of the atmosphere, present
causes sufficiently powerful to explain the progressive diminution of
the lake of Valencia. I cannot concur in the opinion of M. Depons*
(who visited these countries since I was there) "that to set the mind
at rest, and for the honour of science," a subterranean issue must be
admitted. (* In his Voyage a la Terre Ferme M. Depons says, "The small
extent of the surface of the lake renders impossible the supposition
that evaporation alone, however considerable within the tropics, could
remove as much water as the rivers furnish." In the sequel, the author
himself seems to abandon what he terms "this occult case, the
hypothesis of an aperture.") By felling the trees which cover the tops
and the sides of mountains, men in every climate prepare at once two
calamities for future generations; want of fuel and scarcity of water.
Trees, by the nature of their perspiration, and the radiation from
their leaves in a sky without clouds, surround themselves with an
atmosphere constantly cold and misty. They affect the copiousness of
springs, not, as was long believed, by a peculiar attraction for the
vapours diffused through the air, but because, by sheltering the soil
from the direct action of the sun, they diminish the evaporation of
water produced by rain. When forests are destroyed, as they are
everywhere in America by the European planters, with imprudent
precipitancy, the springs are entirely dried up, or become less
abundant. The beds of the rivers, remaining dry during a part of the
year, are converted into torrents whenever great rains fall on the
heights. As the sward and moss disappear with the brushwood from the
sides of the mountains, the waters falling in rain are no longer
impeded in their course; and instead of slowly augmenting the level of
the rivers by progressive filtrations, they furrow, during heavy
showers, the sides of the hills, bearing down the loosened soil, and
forming sudden and destructive inundations. Hence it results, that the
clearing of forests, the want of permanent springs, and the existence
of torrents, are three phenomena closely connected together. Countries
situated in opposite hemispheres, as, for example, Lombardy bordered
by the Alps, and Lower Peru inclosed between the Pacific and the
Cordillera of the Andes, afford striking proofs of the justness of
this assertion.

Till the middle of the last century, the mountains round the valleys
of Aragua were covered with forests. Great trees of the families of
mimosa, ceiba, and the fig-tree, shaded and spread coolness along the
banks of the lake. The plain, then thinly inhabited, was filled with
brushwood, interspersed with trunks of scattered trees and parasite
plants, enveloped with a thick sward, less capable of emitting radiant
caloric than the soil that is cultivated and consequently not
sheltered from the rays of the sun. With the destruction of the trees,
and the increase of the cultivation of sugar, indigo, and cotton, the
springs, and all the natural supplies of the lake of Valencia, have
diminished from year to year. It is difficult to form a just idea of
the enormous quantity of evaporation which takes place under the
torrid zone, in a valley surrounded with steep declivities, where a
regular breeze and descending currents of air are felt towards
evening, and the bottom of which is flat, and looks as if levelled by
the waters. It has been remarked, that the heat which prevails
throughout the year at Cura, Guacara, Nueva Valencia, and on the
borders of the lake, is the same as that felt at midsummer in Naples
and Sicily. The mean annual temperature of the valleys of Aragua is
nearly 25.5 degrees; my hygrometrical observations of the month of
February, taking the mean of day and night, gave 71.4 degrees of the
hair hygrometer. As the words great drought and great humidity have no
determinate signification, and air that would be called very dry in
the lower regions of the tropics would be regarded as humid in Europe,
we can judge of these relations between climates only by comparing
spots situated in the same zone. Now at Cumana, where it sometimes
does not rain during a whole year, and where I had the means of
collecting a great number of hygrometric observations made at
different hours of the day and night, the mean humidity of the air is
86 degrees; corresponding to the mean temperature of 27.7 degrees.
Taking into account the influence of the rainy months, that is to say,
estimating the difference observed in other parts of South America
between the mean humidity of the dry months and that of the whole
year; an annual mean humidity is obtained, for the valleys of Aragua,
at farthest of 74 degrees, the temperature being 25.5 degrees. In this
air, so hot, and at the same time so little humid, the quantity of
water evaporated is enormous. The theory of Dalton estimates, under
the conditions just stated, for the thickness of the sheet of water
evaporated in an hour's time, 0.36 mill., or 3.8 lines in twenty-four
hours. Assuming for the temperate zone, for instance at Paris, the
mean temperature to be 10.6 degrees, and the mean humidity 82 degrees,
we find, according to the same formulae, 0.10 mill., an hour, and 1
line for twenty-four hours. If we prefer substituting for the
uncertainty of these theoretical deductions the direct results of
observation, we may recollect that in Paris, and at Montmorency, the
mean annual evaporation was found by Sedileau and Cotte, to be from 32
in. 1 line to 38 in. 4 lines. Two able engineers in the south of
France, Messrs. Clausade and Pin, found, that in subtracting the
effects of filtrations, the waters of the canal of Languedoc, and the
basin of Saint Ferreol lose every year from 0.758 met. to 0.812 met.,
or from 336 to 360 lines. M. de Prony found nearly similar results in
the Pontine marshes. The whole of these experiments, made in the
latitudes of 41 and 49 degrees, and at 10.5 and 16 degrees of mean
temperature, indicate a mean evaporation of one line, or one and
three-tenths a day. In the torrid zone, in the West India Islands for
instance, the effect of evaporation is three times as much, according
to Le Gaux, and double according to Cassan. At Cumana, in a place
where the atmosphere is far more loaded with humidity than in the
valley of Aragua, I have often seen evaporate during twelve hours, in
the sun, 8.8 mill., in the shade 3.4 mill.; and I believe, that the
annual produce of evaporation in the rivers near Cumana is not less
than one hundred and thirty inches. Experiments of this kind are
extremely delicate, but what I have stated will suffice to demonstrate
how great must be the quantity of vapour that rises from the lake of
Valencia, and from the surrounding country, the waters of which flow
into the lake. I shall have occasion elsewhere to resume this subject;
for, in a work which displays the great laws of nature in different
zones, we must endeavour to solve the problem of the mean tension of
the vapours contained in the atmosphere in different latitudes, and at
different heights above the surface of the ocean.