Voyage from Buenos Ayres to Santos--Tropical vegetation in
Brazil--Visit to San Paulo--Journey from San Paulo to Rio
Janeiro--Valley of the Parahyba do Sul--Ancient mountains
of Brazil--Rio Janeiro--Visit to Petropolis--Falls of
Itamariti--Struggle for existence in a tropical forest--The
hermit of Petropolis--Morning view over the Bay of Rio--A
gorgeous flowering shrub--Visit to Tijuca--Yellow fever
in Brazil--A giant of the forest--Voyage to Bahia and
Pernambuco--Equatorial rains--Fernando Noronha--St. Vincent
in the Cape de Verde Islands--Trade winds of the North
Atlantic--Lisbon--Return to England.
[_EMBARCATION AT BUENOS AYRES._]
About midday on June 30, I took my departure from Buenos Ayres. The
operation was not altogether simple or to be quickly accomplished.
Jolting heavily over the ill-paved streets, a hackney coach carried me
and a fellow-traveller with our luggage to the riverbank. The sight was
very strange. It was a busy day, and there were literally hundreds of
high-wheeled carts engaged in carrying passengers and goods out to the
boats, which lay fully half a mile from the shore. When, after a delay
that seemed excessive, we were installed in a boat, this was pulled in
a leisurely fashion to the steam-tender, which lay more than a mile
farther out. When the hour fixed for the departure of the tender was
long past, we at length got under way, and finally reached the Neva
steamship of the Royal Mail Company, about fourteen miles below the
city, at five o’clock.
With iron punctuality dinner was served at the regular hour, although
none of the passengers were ready, and the luggage was not brought on
board till after dinner. There was, in truth, no reason for haste, as
we were appointed to call at Monte Video on the following morning. My
chief business at that place was to recover possession of the chest
containing my botanical collections, which I had deposited at the
custom-house.
Impressed with the attractions of Brazil, and feeling the strict limits
of time to which I was bound, I asked myself if I should not have done
better to have omitted a visit to the Plata region, and saved nine
days by proceeding direct to Brazil in the _Iberia_, which started
on the 22nd of June. I should certainly recommend that course to any
naturalist travelling under similar circumstances at the same season;
but I am sure that, if I had done so, I should have felt regret at
having missed an opportunity, and should have fancied that I had lost
new and interesting experiences.
At four p.m. on the 1st of July the big ship began to move from her
moorings opposite Monte Video, and for about sixty miles kept a due
easterly course. Somewhere near the port of Maldonado we passed a
bright light on an island which shows as a bold headland. I was told
that this is known as Cape Frio, because of the cold often encountered
here by those arriving from Brazil. It may be supposed that the force
of the south-west wind which prevails in winter is more felt as the
wide opening of the great estuary is reached. During my own short stay,
the wind never rose beyond a gentle breeze, and the temperature on land
was no more than agreeably cool, usually between 55° and 60° Fahr.
during the day.
[_VOYAGE TO SANTOS._]
The distance from Monte Video to Santos, which is reckoned at 970 sea
miles, was accomplished in about three days and eighteen hours. The
voyage was uneventful. On the 3rd we approached the Brazilian coast,
but the land lay low, and no objects could be distinguished. The
weather was all that could be desired by the most delicate passengers,
the barometer remaining almost stationary at about 30·2 inches,[42]
and the temperature by day rising gradually from 57° at Monte Video
to 62° in lat. 25° south. Before sunrise on the morning of July 5, we
entered the bay through which the Santos river discharges itself into
the Atlantic, and found ourselves in a new region. The richness of the
green and the luxuriance of the foliage recalled the aspect of the
coast at Jacmel, in Hayti, and as the morning advanced, while we slowly
steamed towards the head of the bay, I had no difficulty in deciding
on a course which had already suggested itself to my mind. I knew that
Santos is connected by railway with São Paulo (better known in the
form San Paulo), the chief town of this part of Brazil, and that the
railway between that place and the capital was also completed; and I
accordingly determined to leave the steamer, and find my way by land
to Rio Janeiro.
Santos is an ancient place which had long remained obscure, until
the great development of coffee-cultivation in South Brazil, and the
construction of a railway to the interior, have made it the most
advantageous port for the shipment to Europe of that important product.
It lies at the mouth of an inconsiderable stream that enters the head
of the bay. Seen from the sea, it appears to be backed by a range of
lofty, flat-topped hills, but, in truth, these are no more than the
seaward face of the great plateau which extends through a considerable
part of the province of San Paulo. Although Santos is placed a few
miles south of the Tropic of Capricorn, the aspect of the vegetation
is completely tropical; and if a stranger were in doubt, the fringe of
cocoa-nut palms on the shores of the bay would completely reassure him.
Although the thermometer on board ship did not rise above 67°, the air
seemed to us, arriving from the south, very warm, and we were surprised
to hear the company’s agent, when he came on board, complain that he
had found the water in his bath uncomfortably chilly.
I landed with a young German fellow-traveller who, like myself,
intended to proceed to San Paulo; and, as we found that the train was
not to start for three hours, we occupied the time in ascending the
nearest hill. It was now nearly three months since I had enjoyed a
glimpse of true tropical vegetation in the forest of Buenaventura,
and the interest and delight of this renewed experience can never be
forgotten. It was clear that on the slopes about Santos the native
forests had been cleared, but on all the steeper parts, not reclaimed
for cultivation, the indigenous vegetation had resumed the mastery.
Trees and shrubs in wonderful variety contended for the mastery, and
maintained, as they best could, a precarious struggle for existence
with a crowd of climbers and parasites. So dense was the mass of
vegetation that it was impossible to penetrate in any direction farther
than a few yards, and there was no choice but to follow the track that
led to the summit of the slope, on which stood a pretty house with an
adjoining coffee-plantation. Among the many new forms of vegetation
here seen, the most singular was that of the _Tillandsia_.[43] Long,
whitish, smooth cords hang from the branches of the taller trees, and
at eight or ten feet from the ground abruptly produce a rosette of
stiff leaves, like those of a miniature pine-apple, with a central
spike of flowers. But the most brilliant ornament of this season was
a species of trumpet-flower (_Bignonia venusta_, Ker = _Pyrostegia
ignea_, Presl), which, partly supporting itself, and partly climbing
over the shrubs and small trees, covered them with dense masses of
brilliant orange or flame-coloured flowers.
[_TROPICAL VEGETATION AT SANTOS._]
Laden with specimens, I returned to the town just in time for the
afternoon train to San Paulo. The railway was constructed by an English
company, and is so far remarkable that a somewhat difficult problem has
been solved in an efficient and probably economical fashion. The object
is, within a distance of a few miles, to raise a railway train about
2500 feet. This is done by four stationary engines. The line is laid on
four rather steep inclines, with nearly level intermediate spaces, each
ascending train being counterpoised by one descending in the opposite
direction, and the loss of time in effecting the connections is quite
inconsiderable.
On every map of Brazil that I have seen, the Serra do Mar, which we
were here ascending, is represented as a range of mountains running
parallel to the coast, and extending from near Rio Janeiro to the Bay
of Paranagua in South Brazil, apparently dividing the strip of coast
from the low country of the interior. Most travellers would probably
have expected, as I did, that on reaching the summit we should descend
considerably before reaching San Paulo, and it was with surprise that
from the summit I saw before me what appeared to be a vast level plain,
with some distant hills or mountains in the dim horizon. It is true
that the drainage of the whole tract is carried westward and ultimately
reaches the Paranà; but the slope is quite insensible, and I do not
think that, in the space of about sixty miles that lay between us and
San Paulo, the descent can exceed two or three hundred feet. There was
a complete change in the aspect of the vegetation, and open tracts of
moorland recalled scenes of Northern Germany.
Night had closed before we reached the station at San Paulo. There was
a difficulty about a carriage to convey us to the hotel. Perhaps the
demands were unreasonable, or perhaps we were too unfamiliar with the
coinage of Brazil, which is that of the mother country; but on hearing
from the driver a demand for several thousand rees, we indignantly
resolved to walk, and engaged a man to convey our luggage to the hotel.
We were favourably impressed by the appearance of this provincial
capital. In the space of a mile we passed through several good streets,
well lighted with gas, and better paved than any I had seen in South
America. Many handsome houses with adjoining gardens were passed on the
way, and, on reaching the Grand Hotel, nice clean rooms, and good food
provided for the evening meal, further conduced to favourable first
impressions of Brazil.
[_GERMAN COMMERCIAL TRAVELLERS._]
My young German companion, a traveller for a commercial house, was
returning from a visit to the interior of Brazil. By steamer on the
Paranà and Paraguay he had gone from Buenos Ayres to Cuyabà, the
capital of the province of Matto Grosso, a vast region with undefined
boundaries, probably larger than most of the European states. I have
often been struck by the results of superior education among Germans
engaged in business, as compared with men of the same class in
other countries. It is not that they often merit the designation of
intellectual men, and still more rarely do they show active interest in
scientific inquiry; but they retain a respect for the studies they have
abandoned, are ready to talk intelligently on such subjects, and, as a
rule, have a regard for accuracy as to facts which is so uncommon in
the world, as much because the majority are too ignorant to appreciate
their importance as owing to deliberate disregard of truth. I did not
learn much as to the progress of inner Brazil, but my fellow-traveller
mentioned a few particulars that had struck him as singular. He found
the civil population of Cuyabà solicitous in their adherence to
European fashions in dress, and, as a special note of respectability,
the men always appearing in what are vulgarly called chimneypot hats.
The current coin in all but small transactions consisted in English
sovereigns, but he was unable to explain how these have reached a
region which can have so few commercial relations with this country. He
departed on the following morning, while I resolved to spend a day in
visiting the neighbourhood of the city.
Although San Paulo lies exactly on the southern tropic, the winter
climate is positively cool, and at sunrise on July 6 the thermometer
stood at 58° Fahr. On a rough estimate from a single barometric
observation it stands about 2400 feet above the sea. Its appearance
was altogether unlike that of all the towns seen in Spanish America.
The somewhat wearisome monotony of regular square blocks gave place to
the irregular arrangement of some of the provincial towns in England,
several streets running out into the country and ending in detached
villas. The general impression was that of comfort and prosperity.
Several well-appointed private carriages were seen in the streets, and
the shops were as good as one commonly sees in a European town of the
same class.
I was much interested by the short country excursion, which occupied
most of the day, and by an aspect of vegetation entirely new to me. The
plants, with scarcely an exception, belonged to genera prevailing in
tropical America, many of them now seen by me for the first time; but
the species were nearly all different from those of the coast region,
and the general aspect of the flora still more markedly different.
There was no trace of that luxuriance which we commonly expect in
tropical vegetation; monocotyledonous plants, except grasses, were very
few, and, in place of the large ferns that abounded at Santos, I found
but a single _Gleichenia_, allied to a species that I had gathered in
the Straits of Magellan.
[_FLORA OF THE BRAZILIAN PLATEAU._]
Although a fair number of plants were still in flower, I soon came
to the conclusion that night frosts must be not unfrequent at this
season, and that a considerable proportion of the vegetation must be
annually renewed. I found several groups of small trees, chiefly of the
laurel family, and for the first time saw the _Araucaria brasiliensis_,
possibly in a wild state; but none of the trees attained considerable
height, and I doubt whether in a state of nature this plateau has
ever been a forest region. I was rejoiced to see again, growing in
some abundance, the splendid _Bignonia venusta_, and was led to doubt
whether its real home may not be in the interior, and its appearance at
Santos due to introduction by man.
We possess a fair amount of information as to the climate of the
Brazilian coasts, but our knowledge of the meteorology of the interior
provinces is miserably scanty. I was led to conjecture that, although
the district surrounding San Paulo is not divided by a mountain range
from the neighbouring coast region, the climate must be very much
drier, and that the rainfall is mainly limited to the summer season.
In the course of my walk, I unexpectedly approached a country house
about three miles from the town, and was somewhat surprised by meeting
a carriage with ladies on their way to the house. As far as my
experience has gone in the country parts of Portugal or Spain, such an
encounter would there be regarded as a very unusual phenomenon.
The railway from San Paulo to Rio Janeiro appears to be a well-managed
and prosperous concern, paying to its shareholders dividends of from
ten to twelve per cent. The distance is about 380 miles, and the trains
perform the distance in about thirteen and a half hours. Leaving
my hotel in the dark, I found at the station a crowd of passengers
contending for tickets; but good order was maintained, and we started
punctually at six o’clock. For some way the line is carried at an
apparent level over the plain, with occasional distant views of high
hills to the north, and crosses two or three inconsiderable streams,
whose waters run to the Paranà. A slight but continuous ascent,
scarcely noticed by the passing, traveller, leads to the watershed
which, in this direction, limits the vast basin of the Paranà. After a
long but very gentle descent, we reached a stream flowing westward. I
at first supposed it, like those already seen, to be a tributary of the
Paranà which made its way through some depression in the low ridge over
which we had passed; but I soon ascertained that this was an error.
Near the spot where the railway crosses it, the stream makes a sharp
turn, and thenceforth proceeds in a direction little north of east for
about four hundred miles, till it falls into the Atlantic at São João
da Barra, north-east of Rio Janeiro. This is the Rio Parahyba do Sul,
not to be confounded with the Rio Parahyba north of Pernambuco, nor yet
with the more important river Paranahyba in the province of Piauhy.
[_GEOLOGY OF EASTERN BRAZIL._]
For the greater part of the way to Rio the railway runs parallel with
the river. As laid down on the maps, the valley lies between a mountain
range called the Serra da Mantiqueira on the left, and a minor range,
which divides the upper course of the river from the middle part, where
it flows in the opposite direction. The appearance of the country
through which I now passed forcibly suggested to me views respecting
its geological history, which were confirmed and extended by what I
afterwards saw in the neighbourhood of Rio, and by all that I have
since been able to learn on the subject.
I had already been struck by what little I had seen of the plateau
region of the province of San Paulo. Beneath the superficial crust
of vegetable soil, the plateau appears to be formed of more or less
red arenaceous deposits, such as would result from the erosion and
decomposition of the gneiss or granite which is the only rock I had
seen in the country. In the valley of the Parahyba, the connection
was unmistakable. Every section in the valley showed thick beds of
the same coarse-grained, red arenaceous deposits, and on the slopes
the same material lay at the base of whatever masses of granite we
approached. But what especially struck me were the forms and appearance
of the mountains on either hand, if that designation could properly
be given to them. I saw nothing that would elsewhere be called a
mountain range. The outlines were in most places rounded and covered
with vegetation, but at intervals occurred steep conical masses, of
the same general type as the sugar-loaf peaks surrounding the Bay of
Rio Janeiro. However steep, the rocks nowhere showed angular peaks or
edges, these being always more or less rounded.
It would be rash to generalize from the partial observations of a
passing traveller; but the broad outlines of the geology of Brazil,
or, at least, of the eastern provinces, have now been well traced,[44]
and some general conclusions may safely be drawn. It is true that
large districts of the interior have been but partially explored, and
remain blanks on the geological map; but the eastern half of Brazil
is undoubtedly ancient land; presenting no trace of secondary strata
except in small detached areas near the coast, and where more recent
tertiary deposits are to be found only in a portion of the great valley
of the Amazons. A mountain range, having various local designations,
but which may best be called the Serra da Mantiqueira, extends from
the neighbourhood of San Paulo to the lower course of the Rio San
Francisco, for a distance of twelve hundred miles, and this is mainly
composed of gneiss, sometimes passing into true granite, syenite, or
mica schist; and the same may be said of the Serra do Mar, a less
considerable range lying between the main chain and the coast. The
southern limits of the Serra do Mar do not appear to be well-defined,
but we may estimate its length at from five to six hundred miles. The
other mountain systems of the empire are less well known; but I believe
that the ranges dividing the province of Minas Geraes from Goyaz, and
the so-called Cordillera Grande of the province of Goyaz, lying between
the two main branches of the great river Tocantins, are largely formed
of ancient sedimentary rocks of the Laurentian and Huronian groups.
[_DISINTEGRATION OF GRANITE._]
The granite of the Serra da Mantiqueira and Serra do Mar is
coarse-grained, with large crystals of felspar, and is therefore
much exposed to disintegration. So far as I know, the vast masses of
detritus forming the plateaux of this region show no other materials
than such as would be produced by the disintegration of the crystalline
rocks, and there is strong reason to believe that these have never been
overlaid by sedimentary deposits.
Let us now consider what must have been the past history of a region
formed of such materials, exposed, during a large part of the past
history of the earth, to the action of the elements. In such an inquiry
one of the chief points for consideration is the amount of rainfall.
The direct effect, both mechanical and chemical, of rain falling on a
rock surface is perhaps not the most important. Still more essential is
its action in removing the disintegrated matter, and thereby exposing
a fresh surface to renewed action. The difference in the absolute
result due to abundant or deficient rainfall would be found, if we
could calculate it accurately, to be enormous. In a nearly rainless
country, such as Egypt or Peru, we see a slope covered with _débris_,
and are apt to conclude that the rock is being rapidly disintegrated;
but, in truth, what we see is the work of many, perhaps many hundred,
centuries, which remains _in situ_ because there is no agency to remove
it. In a land of heavy rainfall the _débris_ is speedily carried to
lower levels, and the work of destruction is constantly renewed.
We have scarcely any observations of rainfall in the mountain districts
of Brazil. The only reliable return that I have seen is that of one
year’s rainfall at Gongo Seco, in Goyaz, which amounted to more than
a hundred and thirty inches; but we may safely conclude that it is
everywhere very great. It is also important to note that if, as most
geologists now believe, the Atlantic valley has existed since an early
period of the earth’s history, Eastern Brazil must always have been a
land of heavy rainfall. A great mountain range on the eastern side of
the continent might have created a desert region in the interior, but
would have received in the past as much aqueous precipitation as it
does at the present time.
We have, therefore, to consider what must have been the ancient
condition of a region subjected throughout vast periods of geological
time to the utmost force of disintegrating agencies applied to a
rock very liable to yield to them, and where, without reckoning the
large proportion which must have been carried by rivers to the sea,
we see such vast deposits of the disintegrated materials formed out
of the same matrix. To my mind the conclusion is irresistible that
ancient Brazil was one of the greatest mountain regions of the earth,
and that its summits may very probably have exceeded in height any
now existing in the world. What we now behold are the ruins of the
ancient mountains, and the singular conical peaks are, as Liais has
explained, the remains of some harder masses of metamorphic gneiss,
of which the strata were tilted at a high angle. As the same writer
has remarked, although the crystalline rocks are for the most part
easily disintegrated, some portions are formed of much more resisting
materials, and these have to some extent survived the incessant action
of destructive forces.
[_RUINS OF THE ANCIENT MOUNTAINS._]
We are far from possessing the materials for a rational estimate of
the probable extent and elevation of the ancient mountain ranges of
Brazil. In the first place, we have a plateau region occupying a large
part of the upper basin of the Paranà, with an area of fully 100,000
square miles, covered with detritus to an unknown, but certainly
considerable, depth. In addition to this, it cannot be doubted that the
finer constituents carried down by that river, and its tributary the
Paraguay, from the same original home, have largely contributed to the
formation of the Argentine pampas and Paraguay, including the northern
portion of the Gran Chaco. Borings and chemical analysis of the soil
may hereafter give us reliable data; but in the mean time we may safely
reckon that an area of 200,000 square miles has been mainly formed
from the materials derived from the ancient mountains whose importance
I endeavour to point out. In addition to all this, we should further
reckon the soluble matter and fine silt carried to the ocean during
the long course of geological history, and take into account that the
same great mountain region also furnished materials to streams which
flowed northward and eastward.
In attempting to speculate on the past history of this region it is
important to remark that, so far as evidence is available, there is
reason to believe that Brazil has undergone less considerable changes
of level than most other parts of the earth’s surface. Even if we go
back to the period of the earlier secondary rocks, there is no evidence
to show that movements of elevation or depression have exceeded a few
hundred feet.
I have attempted elsewhere[45] to give a sketch of the views which I
hold as to the probable origin of the chief types of phanerogamous
vegetation. I there pointed out that, at a period when physical
conditions in the lower regions of the earth’s surface were widely
different, and the proportion of carbonic acid gas present in the
atmosphere was very much greater than it has been since the deposition
of the coal measures, it was only in the higher region of great
mountain countries that conditions prevailed at all similar to those
now existing. I further argued that, if the early types of flowering
plants were confined, as I believe they were, to the high mountains, we
could not expect to find their remains in deposits formed in shallow
lakes and estuaries until after the probably long period during
which they were gradually modified to adapt them to altered physical
conditions.
[_VALLEY OF THE PARAHYBA._]
A general survey of the South American flora shows, along with elements
derived from distant regions, a large number of types either absolutely
peculiar to that continent, or which, in some cases, appear to have
spread from that centre to other areas. Of these peculiar types some
may probably have originated in the Andean chain, but as to the
majority, it seems far more probable that their primitive home was in
Brazil; and it is precisely on the ancient mountains of this region
that I should look for the ancestors of many forms of vegetation which
have stamped their character on the vegetation of the continent.
I should be the first to admit that the views here expressed have no
claim to rank as more than probable conjectures; but I hold that these,
when resting on some positive basis of facts, are often serviceable to
the progress of science, by stimulating inquiry and leading observers
to co-ordinate facts whose connection had not previously been apparent.
In following the valley, in places where the siliceous soil supported
only a scanty vegetation, I was struck by the singular appearance
of scattered piles, usually about four feet in height, having much
the appearance of rude milestones, occurring here and there in some
abundance, but never very near each other. I was often able to avail
myself of the short halts of the train at wayside stations to secure
specimens of interesting plants, but I was not able to approach near
to these unknown objects. I have no doubt, however, that they were
habitations of termites, or, as they are commonly called, white ants.
I have never been able to conjecture the origin of the instinct that
induces so many species of termites in different parts of the world to
construct dwellings in this form, nor what advantage they can derive
from it.
As the Parahyba appeared to be a rapid-flowing stream, it is probable
that in following the valley the railway descends considerably before
it reaches the point, about eighty miles north of Rio, where it
abruptly turns away from the river to make its way to the capital.
The appearance of the vegetation announced a change of climate, but I
did not notice any palms by the way. The country between the Parahyba
valley and the coast appears to be an irregular mountain tract, nowhere
of any great height, with projecting summits rising here and there
of the same general character as those already described, and the
railway follows a sinuous course so as to select the lowest depressions
between the neighbouring bosses of granite. As we wound to and fro,
constantly changing our direction amid scenes of increasing loveliness,
night closed with that suddenness to which one becomes accustomed in
the tropics, and the last part of the way was unfortunately passed in
darkness. The approach to Rio must be surpassingly beautiful, but,
beyond the fantastic outlines of the surrounding mountains, little
could be discerned save the lights of the city, visible for many miles
before we reached the railway station.
After a long drive through paved streets, I reached the English hotel
(Carson’s), and was curtly informed that the house was full. The next
in rank is the Fonda dos Estrangeiros, to which I proceeded, and found
quarters in a rather shabby room, not overclean. The general style of
the establishment and the food provided answered the same description.
It is generally admitted that the accommodation for strangers in the
capital of Brazil does not come up to the reasonable expectations of
travellers.
[_THE BAY OF RIO JANEIRO._]
By quitting the steamer at Santos, and travelling to Rio by land,
I had gained some slight acquaintance with a new region, but I was
well aware that I had suffered a considerable loss. The view on first
entering the Bay of Rio Janeiro is one of those spectacles that leave
an ineffaceable impression even on persons not very sensitive to
natural beauty, and one on which my fancy from early youth onwards
had most often dwelt. The pursuits of a naturalist, besides their
own fascination, offer additional rewards to all who worship in the
temple of Nature, but they also sometimes exact a sacrifice. Sallying
forth on the morning of July 8, a little under the impression of
the unattractive quarters of the night, I had but very moderate
expectations as to what might be enjoyed of the scenery in the midst of
a large city and its surroundings, but I was speedily disabused. Man
has certainly done little to set off the unequalled fascinations of the
place, but he has been powerless to conceal them. I passed a delightful
day, partly strolling much at random on foot, and occasionally availing
myself of the street-cars, which are frequented by all classes, and
afford a stranger the best opportunity for seeing something of the very
mixed population.
The famous Bay of Rio Janeiro may properly be described as a salt-water
lake, so completely is it landlocked and cut off from the open sea.
About thirty miles long and twenty in breadth, it is large enough
to allow of spacious views, yet not so large as to lose in distance
the marvellous background that is presented in every direction by
the fantastic peaks that surround it. Numerous islands stud the
surface, the larger telling their history in piles of huge blocks,
either simulating rude Cyclopean architecture, or lying in wild
confusion--granite pinnacles, half-decayed or fallen into utter ruin.
The shores are everywhere a maze of coves and inlets, in which land
and water are interlaced; and over all--the mainland and the islands
alike--the wild riot of tropical vegetation holds its sway, defying
the efforts of man to tame it to trimness. Even within the limits of
the city, which stretches for about four miles along the shore, four
or five coves present a ceaseless variety of outline. Of necessity the
plan is completely irregular. Where a space of level ground opens out
between the shore and the rocks, the city has spread out; where the
rocks approach the water’s edge, it is narrowed in places to a single
street. In architecture, since the great era of Alcobaça and Batalha,
the Portuguese have not achieved much, and their descendants in South
America have done little to adorn the capital of their great empire.
The largest building, the imperial palace, might easily be taken for a
barrack. Nature has undertaken the decoration of the city, and, amid
the palms, and under the shade of large-leaved tropical trees in the
public walks and gardens, the absence of sightly buildings is not felt.
The suburb of Botafogo, which is the fashionable quarter, lies on
the shores of the most beautiful of the coves round which the city
has grown up. It mainly consists of a range of handsome villas facing
the sea, each with a charming garden, and, in this season, must be a
delightful residence. But it is generally admitted that the climate
of Rio is debilitating to European constitutions. As compared with
most coast stations in the tropics the heat is not excessive--the mean
temperature of the warmest month (February) is not quite 80° Fahr.,
and that of the coldest (July) about 70°; but most Europeans, and
especially those of Germanic stock, require to be braced by intervals
of cold, if they are to endure a hot climate with impunity. The annual
appearance of yellow fever in the city supplies a still stronger
motive to many of the foreign residents for fixing their abode amongst
the hills. The chief resort, which in summer is frequented by most
of the wealthier classes, is the well-known Petropolis, in the Organ
Mountains, or Serra dos Orgãos, that rise beyond the northern shores of
the bay.
[_THE AVENUE OF PALMS._]
From Botafogo I directed my steps towards the Botanic Garden, and, as
usual among people of Portuguese descent, found great readiness in
giving information to strangers. Following a road that turned away from
the shore, I seemed to have left the city far behind, and be quite in
the country; but presently another beautiful dark blue cove opened
out before me, and again turning inland I reached the garden. I must
confess to a feeling of something like disappointment at the famous
avenue of palms. It has been correctly described as reproducing the
effect of the aisle of a great Gothic cathedral, and the defect, as
it seemed to me, is that the reproduction is too faithful. The trees
of _Oreodoxa regia_, which are about a hundred feet in height, are
all exactly of the same form and dimensions, so much alike that they
appear to have been cast in the same mould, and it is difficult to
persuade one’s self that they are not artificial productions. It may
not be easy to say why the same uniformity which satisfies the eye in
a construction of stone, should fail to do so when similar forms are
represented by natural objects. I suppose the fact to be that in all
æsthetic judgments the mind is unconsciously influenced by trains of
association. Our admiration is aroused not merely by given combinations
of colour or form--by the mere visual image formed on the retina--but
is controlled by our sense of fitness. We should resent as a caprice
of the architect an irregularity in a vista of arches: among objects
endowed with life we expect some manifestation of the universal
tendency to variation.
With an intention, never fulfilled, to make a second visit to the
garden, and, under the guidance of the director, Dr. Glaziou, to make
nearer acquaintance with some of the vegetable wonders there brought
together, I returned to my hotel. Before reaching Rio, I had decided
to devote most of my short remaining time to a visit to the Organ
Mountains, and to make Petropolis my head-quarters. As there was no
especial reason for delay, I started for that place on the morning of
the following day, July 9.
I shall make no attempt to describe the beauties of the bay as they
were successively unfolded during the short passage to and from
Petropolis. From early youth the Bay of Naples has ever appeared to
me so perfectly beautiful that I was very reluctant to admit the
pretensions of a rival. Even now I can well understand that some may
find the pictures presented to the eye on the charmed coasts of our
Mediterranean bay more complete, and the tints of the shores and
sea and sky more harmonious; but there could be no doubt as to the
gorgeous vesture that everywhere adorns this land. The vegetation of
the Mediterranean coasts seems but poor and homely after the eye has
dwelt on the luxuriance of tropical life, as though one were to compare
a garb of homespun with trappings of velvet and embroidery. The islands
of the bay present a ceaseless variety. Some are mere rocks, on which
sea-birds of unknown aspect stood perched. Many of the larger are
inhabited, and one, as I heard, has a population of thirteen hundred
souls, and several charming villas showed it to be a favourite resort.
[_THE ORGAN MOUNTAINS._]
In about an hour and a half from the city, the little steamer ran
alongside of a wooden jetty at a spot on the northern side of the bay
facing the bold range of the Organ Mountains, which extend for over
twenty miles in an easterly direction. Between the northern shore and
the foot of the mountains is a level swampy tract, evidently filled up
by the detritus borne down by the numerous streams, and beyond this
the mountain range rises very abruptly from the plain. Somewhat to my
disappointment, I ascertained that Petropolis lies at a considerable
distance from the higher part of the Organ range to which my attention
had hitherto been directed. It is towards its eastern extremity that
the Serra shows that remarkable series of granitic pinnacles of nearly
equal height, appearing vertical from a distance, that suggested the
likeness to the pipes of an organ whence these mountains obtained their
name. The height of the loftier part has been estimated at 7500 feet
above sea-level. I do not think that any of the summits near Petropolis
can surpass the level of 5000 feet.
A short train with a small locomotive carried passengers for Petropolis
across the low tract to the point where the ascent abruptly commences,
a distance of nine or ten miles. The marshy plain is doubtless
fever-stricken, and we passed very few houses on the way to the
terminus, which is appropriately named Raiz da Serra. The construction
of a railway on the slope leading thence to Petropolis, up which trains
should be drawn by a wire rope, had been commenced, but at the time
of my visit passengers were conveyed in carriages, each drawn by six
or eight mules. A well-kept and well-engineered road--by far the best
mountain road that I have seen in any part of America--leads to the
pass or summit of the ridge that divides Petropolis from the Bay of
Rio. The views during the ascent, especially in looking back over the
bay, were entrancing, and new and strange forms of vegetation showed
themselves at each turn of the road. From the summit, a gentle descent
of a couple of miles leads to the main street of Petropolis.
The place lies about 2900 feet above the sea, in a basin or depression
amidst forest-covered hills. The abundant rains of this region have
carved the surface into a multitude of little dells and recesses,
separated by hills and knolls of various size and height, leaving in
their midst one comparatively broad space, where most of the buildings
are grouped. The streamlets that issue from every nook in the mountains
are finally united in two streams that flow in opposite directions, but
both, I believe, ultimately find their way northward to the Parahyba.
The streamlets have been turned to account by the inhabitants, for
on each side of the main streets a rivulet of crystal water serves
to maintain the vigour of a line of trees supplying the one need of
the long summer--shelter from the vertical midday sun. In the present
season (mid-winter) only one hotel was open; but in summer, when all
who can do so escape from the oppressive heat of Rio, two or three
others are generally crowded. It is at once apparent that Petropolis
is a place for rest and enjoyment, not for business. The few shops and
hotels are all in the main street, Rua do Imperador; the other streets,
or roads, lie between ranges of detached villas, each with a garden,
and here and there some more secluded habitation is withdrawn into some
nook on the margin of the forest.
[_ATTRACTIONS OF PETROPOLIS._]
The large majority of the trees and shrubs of this region have
persistent leaves, but a few lose their foliage annually in winter, and
a few others, I believe, during the heat of summer. The only prominent
reminder of the fact that we were in winter was the appearance of
the _Bombax_ trees that line the main street, now completely bare
of foliage. The tree commonly planted in this part of Brazil is, I
believe, the _Bombax pubescens_ of botanists. The fruit, with its
copious silky appendage to the seeds, alone remained at this season;
but when covered with a mass of large white flowers, it must have a
gorgeous appearance.
I cannot feel sure that every naturalist will approve of the
resolution, which I very soon formed, to remain as long as was possible
at Petropolis. To reach the higher summits of the Organ Mountains would
have required at least three or four days’ travel, and at this season
I could expect to see very little of the vegetation of the higher
zone. In the mean time, I found in the immediate neighbourhood, within
a radius of four or five miles, an unexhausted variety of objects of
interest, and the attractions of the place were doubtless heightened by
the fortunate circumstances in which I found myself. It is certain that
the ten days that I spent at this fascinating spot remain in my memory
as the nearest approach to a visit to the terrestrial paradise that I
can expect to realize. Besides the British minister, Mr. Corbett, I
was fortunate enough to make the acquaintance of two English families,
whose constant kindness and hospitality largely contributed to the
enjoyment of my stay. To find in the midst of the marvels of tropical
nature the charms of cultivated society, was a combination that I had
not ventured to promise to myself.
Although I never went farther than five or six miles from my
head-quarters, the variety of delightful walks in every direction
seemed to be inexhaustible; go where one would, it seemed certain
that one could not go wrong. I soon ascertained, indeed, that it is
useless to attempt to penetrate the forests, except by following a
road or cleared path. My first lesson was on the slope of a little
hill some three hundred feet in height that overlooks the town. I was
told that there was a path on the farther side, but, seeing the ground
partly open, with trees of small stature not much crowded together, I
resolved to follow the straight course. The ascent cost me over two
hours of hard work, and I accomplished it only with the help of a sharp
knife, by which to cut through the tangle of vegetation. In the midst
of this I was surprised to find tall fronds of our common English
bracken (_Pteris aquilina_), a fern that has been able to adapt its
constitution to all but the most extreme climates of the world. The
little hill that cost me so much labour had been completely cleared ten
years before, so that all the trees and shrubs had grown up since that
time.
[_THE STRUGGLE FOR EXISTENCE._]
The first excursion recommended to every stranger at Petropolis is that
to the Falls of Itamariti. I went there twice, varying somewhat my
course--the first time with a horse, which I found quite unnecessary
and rather an incumbrance; the second time alone. The falls are not
very considerable. A stream so slender that it can be passed by
stepping-stones falls over two ledges of granite rock, together about
forty feet in height; but, framed in a mass of the most luxuriant
tropical vegetation, the whole forms a lovely picture. For some reason
which I did not learn, the forest on the slopes of the lower part of
the glen below the falls had been felled just before my visit, and
its beauty had vanished, but fortunately the arm of the destroyer was
arrested before reaching the falls.
As happens to every stranger in a tropical forest, I was bewildered
amidst the great variety of trees that struggle for supremacy, the
one condition for victory being to get a full share of the glorious
sunshine overhead. By vigorous tugging at one of the _lianes_ that hung
like a rope from a branch sixty feet above my head, I succeeded in
breaking off a fragment, and identifying one of the larger trees as a
species of fig, with large, oval, leathery leaves somewhat like those
of a magnolia. It is needless to say that each tree is invaded by a
host of enemies--parasites that fatten on its substance, comparatively
harmless epiphytes that cling to the branches, and hosts of climbing
lianes that mount to the topmost branches, robbing them of their share
of sunlight, and hang down, often twined together, and in the deep
shade are generally mere bare flexible stems. It was strange to observe
that one of the deadliest enemies, a small parasite, fixing itself
near the ground on the trunks of the larger trees, is a species of
fig, belonging to the same genus as some of the giants of the forest,
and doubtless tracing its descent from a common ancestor. It is in the
tropical forest that one feels the force of Darwin’s phrase “struggle
for existence,” as applied to the vegetable world. In our latitudes
it is by an effort of the imagination that we realize the fact that
in our fields and woodlands there is a contest going on between rival
claimants for the necessary conditions of life. Here we see ourselves
in the midst of a scene of savage warfare. The great climbers, like
monstrous boas, that twine round and strangle the branch, remind one
of the Laocoon; the obscure parasite that eats into the trunk of a
mighty tree till a great cavity prepares its downfall, testifies to the
destructive power of an insidious enemy.
[_THE HERMIT OF PETROPOLIS._]
It is only in the more open spots that a botanist is able to make
close acquaintance with the smaller trees and shrubs. Near to the
stream I was able to hook down a branch and secure flowering specimens
of a _Begonia_ that grew to a height of over twenty feet. In such
situations _Melastomaceæ_ were everywhere abundant, but for variety
of forms the ferns surpassed any of the families of flowering plants.
I was surprised to find that the beautiful tree ferns, that add so
much to the charm of the tropical flora, were rarely to be found
with fructification, and the huge fronds being of quite unmanageable
dimensions, I did not attempt to collect specimens. Of the smaller
kinds, when I was able, with the kind assistance of Mr. Baker, of Kew,
to name my specimens, I found that I had collected thirty-five species
in the neighbourhood of Petropolis.
During my stay here I visited a German gentleman whose singular
manner of life excites the interest and curiosity of the European
residents. I am ignorant of the motives that have led Mr. Doer,
evidently an educated and cultivated man, to lead the life of a
hermit far from his native country. He has built for himself a small
house in the forest, on one of the hills that enclose the basin of
Petropolis, and lives quite alone, except for the daily visit of a
boy who carries the provisions that satisfy his very moderate wants.
He seems to be entirely occupied in studying the habits of the native
animals of the country, and especially those of the Lepidopterous
insects--butterflies and moths--that adorn this region. By attention
to the habitual food of the various species, he has succeeded in
keeping in his house the caterpillars that in due time produce the
perfect insect, and has preserved in cabinets large collections of fine
specimens.
At the suggestion of the friend who accompanied me, Mr. Doer was good
enough to introduce me to the family of small monkeys which he has
raised and domesticated. The senior members had been brought from
some place in Northern Brazil, but they had multiplied, some of the
offspring being born in his house, and now formed a rather numerous
party. The creatures habitually passed the day in the forest, never,
in Mr. Doer’s belief, wandering to a distance from the house, and at
night came in and nestled among the rafters of the roof. The call was
by a peculiar note, somewhat resembling a low whistle, repeated two or
three times, and before a minute had elapsed the little creatures came
swarming about the open window. They were decidedly pretty, their large
black eyes giving an impression of intelligence, but I did not detect
any indication of attachment to their master. I cannot say to what
species they belonged. They had large ears like those of the marmoset,
but differed in having a prehensile tail. One of them hung with his
head downward, suspended by the tail from some projection above the
window. After receiving some fragments of sweetmeat they soon departed,
returning to their favourite haunts among the trees of the forest.
Starting early one morning, and reaching the crest of the range that
divides Petropolis from the Bay of Rio Janeiro, I enjoyed in great
perfection a spectacle that is commonly visible at this season when the
weather is clear and settled. Before sunrise a stratum of mist extends
over the bay and the low country surrounding it. As I saw it, this
may have been about a thousand feet in thickness when the sun first
reached it, and the fantastic summits of the mountains rose like islets
from a sea of dazzling white. As the sun’s rays began to act, the mist
appeared to melt away from above; the lower hills and the rocky islands
of the bay emerged in succession, and finally the veil completely
disappeared, and the whole wondrous view was completely disclosed.
[_A SEA OF MIST._]
The beautiful effects displayed in the gradual disappearance of mist
as seen from a height in early morning must be familiar to every
genuine mountaineer, and may be enjoyed amongst the hills of the
British Islands. Among my own recollections, a certain morning, when
I stood alone at sunrise on the highest peak of the Pilatus, near
Lucerne, showed the phenomenon in a most striking way, accompanied as
it was by the coloured halo that surrounds the shadow of the observer
thrown on the cloud-stratum below. But in my previous experience the
disappearance of the mist was always accompanied by the upward movement
of some portions of the mass. The surface appears to heave under the
action of force acting from below, and some masses are generally
carried up so as temporarily to envelope the observer. In the view over
the Bay of Rio I was much farther away from the surface of the mist
than in previous experiences of the kind, and I may have been misled by
distance from the scene of action, but, though watching attentively, I
saw no appearance of heaving of the surface or any break in its regular
form. The waste seemed to proceed altogether from the upper surface,
and the emergence of the prominent objects in regular succession gave
direct evidence to that effect.
During the first five days of my visit the weather at Petropolis was
perfectly enjoyable. The temperature varied from about 60° Fahr. at
sunrise to about 70° in the afternoon; but the effect of radiation must
have been intense, as in an exposed situation a minimum thermometer
descended on one night to 46°, and on the next to 44°, and the dew was
heavier than I have ever seen it elsewhere, so that in some places
the quantity fallen from the leaves of the trees made the ground
perfectly wet in the morning. The barometer varied very little, even
after the weather changed, and stood as nearly as possible three inches
lower than at Rio, showing a difference of level of about 2900 feet.
On the 16th of July the sky became overcast, and some rain fell in
the afternoon, the thermometer rising at two p.m. to 73° Fahr., and
moderate rain fell on each succeeding day until the evening of the
19th, but scarcely any movement of the air was perceptible. There is
a remarkable difference in the distribution of rainfall between the
part of Brazil lying within about fifteen degrees of the equator and
the region south of that limit. At Pernambuco (south lat. 8° 4′), out
of an annual rainfall of about a hundred and ten inches, nearly ninety
inches fall during the six months from March to August, and at Bahia,
with less total rainfall, the proportion is nearly the same. But at
Rio Janeiro the rainy season falls in summer, from November to March,
and winter is the dry season. Of an annual rainfall of forty-eight and
a half inches, only five and a half inches fall in the winter months,
June, July, and August, and less than an inch and a half in July. No
doubt the amount of rain is greater at a mountain station such as
Petropolis, while the proportion falling in the different seasons must
be about the same.
[_THE DEVELOPMENT OF INDOLENCE._]
At Petropolis, as well as elsewhere in South America, I was struck by
the fact that the children of European parents born in the country
speedily acquire the indolent habits of the native population of
Spanish or Portuguese origin. The direct influence of climate is
doubtless one cause of the change of disposition, but I suspect that
the chief share is due to the great difference in the conditions of
life which are the indirect results of climate. Where mere existence is
so enjoyable, where physical wants are so few and so easily supplied,
the chief stimulus to exertion is wanting, and the natural distaste for
labour prevails over the hope of gain. A boy will prefer to pick up a
few pence by collecting flowers, or roots, or butterflies in the forest
near his home, to earning ten times as much by walking to a distance,
especially if expected to carry a light weight. On my first visit to
Itamariti I took with me a German boy, whom I left in charge of the
superfluous horse that I had been advised to take with me. Finding the
occupation a bore, and probably fearing that he would have to carry
back the portfolio and vasculum that I had taken for plant-collecting,
he fastened the bridle to a tree and disappeared, never coming to
claim the pay promised for his unaccomplished day’s work.
All delightful times come to an end, and, as I resolved to visit Tijuca
before departing from Brazil, I quitted Petropolis on the morning of
July 20, and made my return to Rio amid brilliant sunshine, in which
the glorious scenery of the bay renewed its indelible impression on
my memory. In passing over the tract of low land between Raiz da
Serra and the shore, partly overgrown by shrubs or small trees ten
or twelve feet in height, I found them covered with masses of large
flowers of the most brilliant purple hue, where ten days before not
a single flower had been visible. The train halted for half a minute
at a solitary half-way house, and I was able to break off a branch
from the nearest plant. It belonged, as I suspected, to the family of
_Melastomaceæ_, and is known to botanists as _Pleroma granulosum_ of
Don; but one seeing dried specimens in a European herbarium, could
form no conception of the gorgeous effect of the masses of rich colour
that were here displayed, outshining the splendours of the Indian
rhododendrons now familiar to European eyes. I again found the same
species at Tijuca; but the soil and situation were, I suppose, less
favourable, and the show of bloom was neither so rich nor so abundant.
I was told that the local name of this splendid plant is _quaresma_,
because it flowers in Lent, which in Brazil falls in autumn; but I
afterwards ascertained that the same name is given to several other
species of _Melastomaceæ_ having brilliant flowers, and it seems
improbable that the same species which I found bursting into flower in
mid-winter should have also flowered three or four months before. The
only remains of fruit that I found were dry, empty capsules that had
apparently survived the preceding summer.
[_THE EMPEROR DOM PEDRO._]
Although I reached Rio some time before midday, so many matters
required my attention that I found it impossible to return for a
fuller visit to the Botanic Garden. Mr. Corbett had kindly offered to
present me to the emperor, and, if time had permitted, I should have
gladly taken the opportunity of making the personal acquaintance of
a sovereign who stands alone among living rulers for the extent and
variety of his scientific attainments, and for the active interest he
has shown in the progress of natural knowledge. Irrespective of the
qualities that appeal to the sympathies of men of science, Dom Pedro
is evidently one of the remarkable men of our time. His exceptional
energies, physical and mental, are incessantly devoted to every branch
of public affairs, and it is said that he has even succeeded in
inspiring some of his subjects with a share of his own zeal. But, so
far as I could learn, he cannot be said to have achieved popularity.
Among indolent and listless people, indefatigable industry produces an
unpleasant effect. Improvements may or may not be desirable, but they
are certain to give some trouble: it would be far pleasanter to let
things remain as they are. Perhaps, whenever the time comes for Brazil
to be deprived of the guidance of the present emperor, its people will
become sensible of the loss they have sustained.
The steamer of the Royal Mail Company was to depart on July 24, so that
no time was to be lost in making my visit to Tijuca. That place lies
among the hills north-west of the city, about nine hundred feet above
the sea, and the distance is quite inconsiderable; but the arrangements
for visitors are inconvenient. A tramway runs over the flat country
to the foot of the hill, and from the terminus the remainder of the
way is accomplished by carriage or omnibus. But no luggage is taken by
the tramway, and this has to be forwarded on the previous day. When I
reached the station, about eleven a.m. on the 21st, I had an unpleasant
quarter of an hour, during which it appeared that the case containing
most of my Petropolis collections was lost or mislaid. At length it
was found lying in an outhouse; no omnibus was available, but I soon
succeeded in hiring a carriage to convey me to Tijuca.
The country between the city and the lower slopes of the hills is
covered with the villas of wealthy natives, many of them large and
handsome houses, each surrounded by a garden or pleasure-ground. In
these grounds the mango, bread-fruit tree, and others, with large thick
leaves giving dense shade, were invariably planted; and here and there
palms, of which I thought I could distinguish four or five species,
gave to the whole the aspect of completely tropical vegetation.
Amidst the mass of trees, it was rarely possible to get a glimpse of
the exquisite scenery surrounding Rio on every side, and it was only
towards the top of the hill that I gained a view of the bay. Tijuca
lies on the farther, or westward, slope, nearly surrounded by forest,
and consists of only a few houses, of which the chief is White’s Hotel.
As I afterwards learned, Mr. White, who is engaged in business in the
city, was in the habit of hospitably entertaining his friends at a spot
which naturally attracted frequent visits, and at length judiciously
turned his house into an hotel, where a moderate number of guests find
charming scenery, comparative coolness in the hot season, and far more
of creature-comforts than are to be had in the hotels of Rio.
[_TREATMENT OF YELLOW FEVER._]
Time allowed me no more than a short stroll in the immediate
neighbourhood before the hour of dinner, at which I met several
intelligent and well-informed gentlemen, and amongst them three English
engineers, from whom I received much information as to the country
which they have made their home.
Amongst other questions discussed was that, so important to Europeans,
regarding the annual visitation of yellow fever and the best method of
treatment. I was especially struck by the experiences of the youngest
of the party, who had come out from England a few years before to
superintend some considerable new works for the drainage of Rio. For
two years he lived altogether in the city, constantly requiring to go
below, and sometimes remaining for hours in the main sewers. During
that time he was never attacked by the fever, and no fatal cases arose
among the workmen engaged in the same work. Since its completion this
gentleman had been engaged on other works of a more ordinary character,
and had habitually slept in the country during the hot season; but,
under conditions apparently more favourable, he had been twice stricken
by the fever. The first attack, which was probably slight, was at once
cut short by a large dose of castor oil and aconite administered by a
friend. In the following year he experienced a more serious attack, and
had been treated by a doctor of good repute, mainly with tartar emetic.
It appears that professors of the healing art in Brazil regulate their
charges, not by the amount of time or labour which they give, but
by the estimated value of the patient’s life. If he survives, it is
considered that the remuneration should be in the nature of salvage--a
considerable percentage on the amount of his income. In the present
case the young engineer had been required to pay a fee of £180. In
some cases, where the doctor’s demand appeared utterly unreasonable,
foreigners have attempted to appeal to the tribunals, but it appears
that the results of litigation have not encouraged others to resort to
the protection of the law.
In answer to my inquiries, most of my informants made light of the
difficulties of exploring the interior of Brazil, but they agreed in
the opinion that much time must be given by any traveller wishing to
break new ground. Even in the more or less fully settled provinces, the
spaces to be traversed are so great, and the means of communication so
imperfect, that a large margin must be left for unexpected delays. One
gentleman, who had travelled far in Goyaz and Matto Grosso, assured me
that he had never encountered any difficulty as to provisions. Three
articles of European origin are to be found, so he assured me, at every
inhabited place in the interior--Huntley and Palmer’s biscuits, French
sardines, and Bass’s pale ale.
[_VEGETATION OF TIJUCA._]
July 22 was a day of great enjoyment, devoted to the immediate
neighbourhood of Tijuca, where objects of interest were so abundant
as to furnish ample occupation for many days. I have said that the
place is almost surrounded by the forest which spreads over the
adjoining hills. I now learned that less than fifty years before, at
a time when coffee-planting in Brazil became a mania, and was counted
on as everywhere a certain source of wealth, the aboriginal forest
which covered the country was completely cleared, and coffee-planting
commenced on the largest scale. Experience soon proved that the
conditions either of soil or climate were unfavourable, and after
a few years the land was again abandoned to the native vegetation.
About thirty-five years had sufficed to produce a new forest, which in
other lands might be supposed to be the growth of centuries. The trees
averaged from two to three feet in diameter, and many were at least
seventy feet in height. One of the largest is locally called _ipa_; it
belongs to the leguminous family, has a trunk nearly quite bare, and
the upper branches bore masses of cream-coloured flowers; but, finding
it impossible to obtain flower or fruit, I have been unable to identify
it. The vegetation here appeared to be even more luxuriant than that
of Petropolis, and to indicate a somewhat higher mean temperature.
The proportion of tree ferns was decidedly greater, and a good many
conspicuous plants not seen there were here abundant. Some of these,
such as _Bignonia venusta_, _Allamanda_, etc., may have strayed from
the gardens; but many more appeared to be certainly indigenous.
Of flowering plants the family of _Melastomaceæ_ was decidedly
predominant, and within a small area I collected fifteen species, eight
of which belonged to the beautiful genus _Pleroma_. One of these (_P.
arboreum_ of Gardner) is a tree growing to a height of forty feet; but
the species of this family are more commonly shrubs not exceeding ten
or twelve feet in height.
I was unfortunately not acquainted at that time with the observations
made near Tijuca by Professor Alexander Agassiz, which appear to him
to give evidence of glacial action in this part of Brazil. It would be
rash, especially for one who has not been able to examine the deposits
referred to, to controvert conclusions resting on such high authority;
but I may remark that the evidence is confessedly very imperfect, and
that the characteristic striations, either on the live rock or on the
transported blocks, which are commonly seen in the theatre of glacial
action, have not been observed. I lean to the opinion that the deposits
seen near Tijuca are of the same character as those described by M.
Liais[46] as frequent in Brazil. The crystalline rocks are of very
unequal hardness, and while some portions are rapidly disintegrated,
the harder parts resist. The disintegrated matter is washed away, and
the result is to leave a pile of blocks of unequal dimensions lying in
a confused mass.
On the following day, my last in Brazil, one of my new acquaintances
was kind enough to guide me on a short excursion in the forest, which
enabled me to approach one of the giants of the vegetable kingdom. At
the time of the clearing of the aboriginal forest two great trees were
spared. One of these had been blown down some years before my visit,
and but one now remained. It was easily recognized from a distance, as
it presented a great dome of verdure that rose high above the other
trees of the forest. The greater part of the way was perfectly easy.
A broad track, smooth enough to be passable in a carriage, has been
cleared for a distance of many miles over the forest-covered hills.
[_A GIANT TREE._]
Following this amid delightful scenery, we reached a point scarcely
two hundred yards distant from the great tree. I had already learned
that even two hundred yards in a Brazilian forest are not very easily
accomplished, but I was assured that a path had been cut a year or two
before which allowed easy access to the foot of the tree. We found the
path, but it was soon apparent that it had been neglected during the
past season, and in this country a few months suffice to produce a
tangle of vegetation not easily traversed.
When at length we effected our object, we found ourselves at the
base of a cylindrical column or tower, with very smooth and uniform
surface, tapering very slightly up to the lowest branch, which was
about eighty feet over our heads. We measured the girth, and found it
just twenty-nine feet at five feet from the ground. It is needless to
say that I could form no conjecture as to the species, or even the
family, to which this giant belongs, as I was quite unable to make out
the character of the foliage. While near to it we could form no guess
as to the height; but my companion, whose profession made him used
to accurate estimates, and who had observed it from many points of
view, reckoned the height at between 180 and 200 feet. I had not then
seen the giant conifers of western North America, but, excluding the
two Sequoias, I have not found any single tree to equal this. In the
valleys of the Alleghany Mountains in Tennessee, I have indeed beheld
not unworthy rivals. The _Liriodendron_ there sends up a stem more than
seven feet in diameter, and frequently exceeds 150 feet in height.
To diminish my regret at quitting this beautiful region, the morning
of July 24 broke amid dark clouds and heavy rain, which continued till
the afternoon. I had counted on enjoying a few hours in Rio before my
departure, but, that being impossible, I went directly from Tijuca to
the landing-place, and thence on board the steamer of the Royal Mail
Company, which was to take me back to England. This was the _Tagus_,
and I had much pleasure in finding her under the command of Captain
Gillies, with whom I had made the voyage from Southampton to Colon.
In the afternoon we slowly steamed out of the bay. Its glories were
veiled, heavy clouds rested on the Organ Mountains; but the Corcovado
and the other nearer summits appeared from time to time, and the last
impression was that of fleeting images of beauty the like of which I
cannot hope again to behold.
The course for steamers from Rio Janeiro to England is as nearly as
possible direct. The coast of Brazil from Rio to Pernambuco runs
from south-south-west to north-north-east, in the same direction
that leads to Europe; and from the headland of Cabo Frio to the
entrance of the English Channel at Ushant, a distance of about 72° of
latitude and 38° of longitude, the helm is scarcely varied from the
same course. It is somewhat remarkable that in so long a voyage, in
which one passes from the Tropic of Capricorn to the region of the
variable anti-trade-winds of the northern hemisphere, it not very
rarely happens, as I was assured by our experienced captain, that
north-north-east winds are encountered throughout the entire distance.
This was nearly verified in the present case. For comparatively short
periods the wind shifted occasionally to the north and north-west;
more rarely, and at brief intervals, light breezes from the south and
south-east were experienced; but the north-east and north-north-east
winds predominated, even on the Brazilian coast, until we reached the
latitude of Lisbon.
[_WINDS OF THE ATLANTIC._]
It is an admitted fact in meteorology, that the trade-winds of the
northern are--at least in the Atlantic--stronger than those of the
southern hemisphere; but at the winter season of the south, the
south-east trade-winds prevail in the equatorial zone, and are not
rarely felt as far as eight or even ten degrees north of the equator.
But in investigating the extremely complex causes that determine the
direction of air currents, and especially those slight movements that
make what is called a breeze, it is difficult to trace the separate
effect of each agent. The neighbourhood of a coast constantly brings
local causes into play, and it may well be that the rapid condensation
of large masses of vapour, such as occurs at each heavy fall of rain,
may determine temporary currents in the air in directions opposed to
the general and ordinary march of the winds. Irrespective, however, of
any such local causes, we must bear in mind the general tendency of
air currents towards motion of a circular or spiral character. When we
meet a breeze blowing in a direction contrary to that which ordinary
experience leads us to expect, we must not forget the possibility that
it may be a portion of the ordinary current which has formed an eddy.
The main facts of meteorology are now well established, but the local
deviations may give room for prolonged study.
Although I knew that the delay at both places would be short, I looked
forward with much interest to the prospect of landing at Bahia and
Pernambuco. The latter place especially is known to be the chief mart
for the natural productions of Equatorial America. Skins of animals,
birds living and dead, gorgeous butterflies and shells, are easily
procurable; and a mere visit to the fish and vegetable markets is
sure to make a visitor acquainted with objects of interest. But my
expectations were doomed to disappointment.
We reached Bahia on the morning of July 27. The city stands on a point
of land north of the entrance to an extensive bay, called by the
Portuguese Bahia de Todos Santos, and the proper name of the city is
São Salvador; but the concurrent practice of foreigners has established
the name now in general use. The steamer lay in the roadstead nearly
a mile from the shore, and the heavy boats, carrying some passengers
for Europe, moved slowly as they pitched to and fro in the swell of
the sea. Just as they came alongside, rain suddenly burst in a torrent
from the clouds, which had formed in the course of a few minutes.
For the first time in my journey, I regretted the omission to have
supplied myself with a waterproof cloak. A thorough wetting in tropical
countries usually entails an attack of fever, and for that I was not
prepared; so, along with two or three other passengers who wished to go
ashore, I remained in the main deck. The rain ceased, and there was an
interval of sunshine; but the torrential showers were renewed two or
three times before we resumed our voyage in the afternoon.
[_COAST CLIMATE OF BRAZIL._]
I have already noticed the contrast that exists between the winter
and summer climate of this part of Brazil and that of Rio and the
southern provinces. In the latter the rainy season is in summer, while
nearer the equator, although no season can be called dry, the chief
rainfall occurs in winter--that is to say, in the season when the sun
is farthest from the zenith. While passing through the equatorial
zone, when intervals of bright weather alternated with extremely heavy
rain, I frequently consulted the barometer, but was unable to trace
the slightest connection between atmospheric pressure and rainfall,
the slight oscillations observed being due to the diurnal variation
everywhere sensible in the tropics.
The temperature on this part of the coast was only moderately warm,
varying from 76° to 78° Fahr. on this and the following day, when we
called at Maceio, a place of increasing commercial importance. Our
stay was so short that no one attempted to go ashore, although the
weather was favourable. Several whales were seen both on the 27th and
28th, but I failed to ascertain to what species they belonged.
On the evening of the 28th we experienced a decided rise of
temperature; three hours after sunset the thermometer still stood at
81° Fahr., and, with two remarkable intervals, it did not fall below
80° during the following eight days. During that time my attention
was often directed to the physiological effects of heat on the human
economy, and both my own experience and the conflicting testimony
of travellers lead me to conclude that there are many facts not yet
satisfactorily explained.
On the enfeebling effect of moist tropical climates there is a general
agreement, both as to the fact and the chief cause; but, as I have
remarked in a preceding page, the circumstance that this is little or
not at all experienced at sea is apparently anomalous. With regard to
the direct effect of the sun’s rays on the surface of the body, and
especially in the production of sun-stroke, the evidence of scientific
travellers is conflicting, and the explanations offered are by no means
satisfactory. On the one hand, it is asserted on good authority that in
the equatorial zone the direct effect of the sun is far greater than
it is in Europe at the same elevation above the horizon. The rapid
reddening and blistering of the skin where exposed, and sun-stroke
from exposure of the head, are said to be the ordinary effects. Being
extremely sensitive to solar heat, I have always carefully protected
my head, and have avoided rash experiments. Of the reddening and
blistering of the skin I have had very frequent experience in Europe,
upon the Alps and other mountains; but I observed none but very slight
effects of this kind in the tropics, even with a nearly vertical sun,
either on land or while at sea. Dr. Hann[47] cites many statements on
the subject. In the West Indies cases of sun-stroke are rare, and the
inhabitants expose themselves without danger. In nearly all parts of
British India, as is too well known, the danger of exposing the head to
the sun is notorious, and the same is certainly true of most parts of
tropical Africa.
[_SUN-STROKE._]
The most obvious suggestion is that, inasmuch as dry air absorbs less
of the solar heat than air charged with aqueous vapour, the injurious
effects should be more felt in dry climates than in damp ones. But,
so far as what is called sun-stroke is concerned, the balance of
evidence is opposed to this conclusion. Sir Joseph Fayrer, who has had
wide experience in India, expressly asserts that the hot dry winds
in Upper India induce less cases of sun-stroke than the moist though
cooler climate of Bengal and Southern India. Dr. Hann quotes Borius
for a statement that in Senegambia the rainy season is that in which
sun-stroke commonly occurs, while he further asserts that on the Loango
coast, in very similar climatal conditions, the affection is almost
unknown, and that Europeans even expose the head to the sun with
impunity.
My own conclusion, fortified by that of eminent authorities, is
that the phenomena here discussed are of a very complex nature; that
different physical agencies are concerned in the various effects
produced on the body; and that most probably there are many different
pathological affections which have been classed together, but which,
when more fully studied, will be recognized as distinct.
In the first place, I apprehend that the action of the sun which causes
discolouration and blistering of the skin has no relation to that
which causes sun-stroke. It is a local effect confined to the surfaces
actually exposed, and, if it could be accurately registered, would
serve the purpose of an actinometer, depending as it does on the amount
of radiant heat reaching the surface in a unit of time.
Sun-stroke proper is, I believe, an affection of the cerebro-spinal
system arising from the overheating of those parts of the body. It
is by no means confined to the tropics, or to very hot countries, as
many cases occur annually in Europe, and still more frequently in the
eastern states of North America.
Nearly allied to sun-stroke, but perhaps sufficiently different to
deserve separate classification, are those attacks which some writers
style cases of thermic fever, which arise mainly in places where the
body is for a continuance exposed to temperatures exceeding the normal
amount of the human body. In producing thermic fever, it would appear
that the depressing effect of a hot moist climate acts powerfully as a
predisposing cause, and such cases not uncommonly arise where there has
been no exposure whatever to the direct rays of the sun.
[_PERNAMBUCO._]
It is easy to understand that, as a general rule, seamen are less
exposed than other classes to any of the injurious effects of heat, but
it is remarkable that they should enjoy complete exemption. Cases are
not very uncommon among seamen going ashore in hot countries, but I
have not found a well-authenticated case of sun-stroke arising on board
ship; and cases of thermic fever in the Red Sea usually arise in the
engine-room of a steamer rather than among the men on deck.
On the morning of July 29 we reached Pernambuco, to which I had looked
forward as the last Brazilian city that I was likely to see. It had
been described to me as the Venice of South America, and the comparison
is to a slight extent justified by its position on a lagoon of smooth
water, separated from the open roadstead by a coral reef several miles
in length. It enjoys the further distinction, unusual in a place within
eight degrees of the equator, of being remarkably healthy. But on this
occasion fortune was against me.
No doubt for some sufficient reason, we did not enter the rather
intricate passage leading inside the reef, but lay to in rough water
outside. For a short time the scene was brilliant. The hot sun beat
down on the deep blue water, and lit up the foam on the crests of the
dancing waves, and the sky overhead showed such a pure azure that one
could not suppose the air to be saturated with vapour. Before long
boats were seen approaching, tossed to and fro in the broken water; but
before they drew near, heavy clouds had gathered in the course of a few
minutes, and a torrent of water was discharged such as I had never
experienced except in passing under a waterfall. As each boat came
alongside, a seat was let down from the upper deck, and the passengers
were hoisted up in turn, those who had not efficient waterproofs being
as thoroughly drenched as if they had been dipped in the sea. Four or
five times during the day the sky cleared, the blazing sun returned,
and the decks were nearly dry, when another downpour of torrential rain
drove us all to seek shelter, each shower lasting only from ten to
fifteen minutes.
During the hotter hours of the day a rather strong breeze set in
towards the shore, and I have no doubt that it is to its full exposure
to this ordinary sea-breeze that the city owes its comparative
healthiness. It was interesting to watch the manœuvres of the
_catamarans_, in which the native fishermen were pursuing their
avocations. This most primitive of sea-craft is formed of two or three
logs well spliced together, with some weight to serve as ballast
fastened underneath. In the forepart a stout stick some ten feet long
stands up as a mast and supports a small sail, and amid-ships a short
rail, supported on two uprights, enabled the two men who form the crew
to hold on when much knocked about by the waves. A single paddle seems
to serve as a rudder, but it is not easy to understand how such a rude
substitute for a boat is able to work out to sea against the breeze
which commonly sets towards the shore.
A large proportion of the steerage passengers who came on board at
Bahia and Pernambuco were Portuguese returning to their native country
after a residence, either as artisans or as agricultural settlers,
in Brazil. My command of the language is unfortunately so limited
that I failed to extract from these fellow-passengers any interesting
information. With scarcely an exception, each carried at least one
parrot, usually intended for sale at Lisbon, where it appears that they
are in some request. Comparatively high prices are given for birds that
freely simulate human speech.
[_THE ANEROID BAROMETER._]
We were under steam in the afternoon of the 29th, and soon lost to
view the South American continent. On the following day the barometer
for the first time showed the diminution of pressure which is normally
found in the equatorial zone. Between nine a.m. and four p.m. the
ship’s mercurial barometer fell about a quarter of an inch from 30·30
to 30·06 inches, and my aneroid showed nearly the same amount of
difference. It must be remembered, however, that nearly one-half of the
effect (at least one-tenth of an inch) must be set down to the daily
oscillation of the height of the barometer, which so constantly occurs
within the tropics, the highest pressures recurring at ten a.m. and ten
p.m., and the lowest about four p.m. and four a.m.
I carried with me on this journey only a single aneroid barometer,
an excellent instrument by Casella, whose performance was very
satisfactory, and which in a very short time returned to its normal
indication after exposure to diminished pressure in the Andes; but
it had the defect, which, so far as I know, is common to the aneroid
instruments by the best makers, that the temperature at which the
scale is originally laid down by comparison with a standard mercurial
barometer is not indicated on the face of the instrument. Assuming that
the aneroid is compensated for variations of temperature, and I have
found this to be the case within ordinary limits in good instruments,
there remains the question to what height of mercury at what
temperature a given reading of the aneroid corresponds. For scientific
purposes it is customary to reduce the reading of the mercurial
barometer to the temperature of the freezing-point of water, and it is
often supposed that the aneroid reading corresponds to that figure. But
we may feel pretty confident that the maker, in laying down the scale,
did not work in a room at freezing-point. I have been accustomed to
assume 15° Cent., or 59° Fahr., as about the probable temperature with
instruments made in our climate.
In the present case, the barometer-reading of 30·06 inches at the
temperature of 84° Fahr. would (neglecting the small correction for
capillarity) be reduced by about fourteen-hundredths of an inch, in
order to give the correct figure at freezing-point; but for comparison
with an aneroid, supposed to have been laid down at 59° Fahr., the
correction would be a fraction over seven-hundredths of an inch. As
a matter of fact, my aneroid marked at four p.m. 29·89 inches, or,
allowing for the correction, just one-tenth of an inch less than the
ship’s mercurial barometer, and, as I believe, was more nearly correct.
As the sun was declining on the evening of July 30, we sighted the
remarkable island of Fernando Noronha. It lies about four degrees south
of the equator, and more than two hundred miles from the nearest
point of the Brazilian coast. The outline is singular, for the rough
hills which cover most of the surface terminate at the western end
of the island in a peak surmounted by a column, in the form of a
gigantic lighthouse, which must rise over a thousand feet above the
sea-level.[48] Although Darwin passed some hours on the island in 1832,
it remains to the present day one of the least known of the Atlantic
islands, so far as regards its natural productions. A fellow-passenger
who had landed there assured me that he had found granite; but I have
no doubt that the island is exclusively of volcanic origin, for such is
the opinion of the few scientific men who have visited it.
[_FERNANDO NORONHA._]
The island has been converted by the Brazilian Government into a
convict station, and in consequence access by strangers has become
very difficult. Such information as we possess is mainly to be found
in Professor Moseley’s account of the voyage of the _Challenger_. On
landing there with Sir G. Nares, he at first obtained permission from
the governor to visit the island and to collect natural objects; but
the permission was very soon retracted, and he was unable to obtain
specimens of several singular shrubs that abound and give the island
the appearance of being covered with forest.
Now that the attention of naturalists has been directed to the especial
interest attaching to the fauna and flora of oceanic islands, and their
liability to extinction owing to competition from species introduced
by settlers, it may be hoped that the exploration of this small but
remarkable island will before long be undertaken by a competent
naturalist. For that purpose it would be, in the first place, necessary
to obtain the permission of the Brazilian Government, and to secure the
means of existence during a stay of ten or twelve days on the island.
The most effectual means would be through direct personal application
to the emperor, who is well known to take a lively interest in all
branches of natural science.
With the thermometer standing about 82°, the passengers naturally
preferred the upper deck to the close air of the saloon, and were
resting in their ship-chairs between nine and ten p.m., when suddenly
there came an outburst of coughing and sneezing, followed by demands
for muffling of every kind. There was no sensible movement in the air,
but I found that the thermometer had fallen to 79° Fahr., and there was
a feeling of chilliness which was not easily explained by that slight
fall of temperature.
The mystery was explained on consulting the chief officer, who
throughout the voyage paid much attention to the temperature of the
sea. Since leaving Pernambuco, the thermometer in buckets brought
up from the surface had varied only between 82° and 83°. On this
evening we had abruptly encountered a relatively cold current, with a
temperature somewhat below 76°, and the effect of being surrounded by
a body of cool water when the skin was in the condition usual in the
tropics was felt by nearly all the passengers.
[_M. GEORGES CLARAZ._]
With slight variation, this comparatively cool current must have
extended over a large area on both sides of the equator, as the
temperature of the water remained nearly the same for about forty-eight
hours.
Throughout the voyage from Brazil to Europe, I was fortunate in
enjoying the society of a man of remarkable intelligence, who has
been a diligent and accurate observer of nature in a region still
imperfectly known. M. Georges Claraz, by birth a Swiss, belonging to a
family of small proprietors in the Canton of Fribourg, had gone out as
a young man to improve his fortune in South America. He had received a
fair scientific education, having followed the lectures of the eminent
men who have adorned the Polytechnic School at Zurich; but, what is
much more rare, he appeared to have retained everything that he had
ever learned, and to have had a clear perception of the scientific
value of the observations that a stranger may make in a little-known
region. After passing some time in the state of Entrerios, he had
settled at Bahia Blanca, close to the northern border of Patagonia. He
had established friendly relations with the Indians, and made frequent
excursions in the interior of Patagonia and southward as far as, and
even beyond, the river Chubat.
During the entire time, although engaged in the work of a settler, M.
Claraz seems to have made careful notes of his observations--on the
native Indians and their customs; on the indigenous and the domestic
animals; on the plants and their uses; on the mineral structure of the
country, not omitting to take specimens of the mud brought down by the
different rivers; and on general physics. Of his large collections
I trust that the greater part have safely reached Switzerland. A
considerable collection of dried plants, sent home while he resided at
Bahia Blanca, was unfortunately lost. He was good enough, after his
return, to send me a smaller collection remaining in his hands, of
which I gave an account in the _Journal of the Linnæan Society_ for
1884.
As I trust that the great store of information collected by M.
Claraz will before long be given to the world, I should not wish to
anticipate the appearance of his work, but I may say that among many
interesting particulars, several of which I noted at the time, I was
especially struck by the evidence collected among the Indians, which
seemed to prove that the _Glyptodon_ survived in Patagonia down to a
comparatively recent period, and that the tradition of its presence is
preserved in the stories and songs of the natives.
Early on July 31 we passed the equator, but it was not till ten p.m.
on the following day that we escaped from the area of cool water and
found the ordinary equatorial temperature of 82·5°. During the three
following days the weather was hot and relaxing, the thermometer
ranging by day between 84° and 85°. For some hours on the 2nd of
August the wind came from south-south-east, but before evening it
backed to west, and blew from that point rather freshly at night. On
the following day we appeared to have met the north-east trade-wind,
which was, however, a gentle breeze, and occasionally veered to the
north-west.
[_ISLAND OF ST. VINCENT._]
In the afternoon of August 4 we made out the picturesque outline of the
Cape Verde Islands, and before sunset entered the channel between St.
Vincent and St. Antão, finally dropping anchor for the night in the
outer part of the fine harbour of St. Vincent. Having been selected as
a coaling station, this has become the chief resort of steamers plying
between Europe and the Southern Atlantic, and we were led to expect
that the operation would take up great part of the following day. Here
a fresh disappointment awaited me. I had confidently reckoned upon
spending several hours ashore, and seeing something of the curious
vegetation of the island, which includes a scanty representation of
tropical African types, with several forms allied to the characteristic
plants of the Canary Islands.
I had not duly taken account of the perverse temper of the officers of
health, whose chief object in life seems everywhere to be to make their
authority felt by the needless annoyance they cause to unoffending
fellow-creatures. We had left Rio with a clean bill of health; not
a single case of yellow fever had occurred for months before our
departure; but Brazil is regarded as permanently “suspected,” and
quarantine regulations were strictly enforced in our case.
I am far from believing that in certain conditions, and as regards
certain diseases, judicious quarantine regulations may not be
effective; but, reckoning up all the loss and inconvenience, and the
positive damage to health, arising from the sanitary regulations now
enforced, I question whether it would not be better for the world if
the system were entirely abolished.
The view of St. Vincent, backed by a bold and stern mountain mass, on
which scarcely a trace of vegetation is visible from a distance, was
for some time sufficiently interesting; but as the day wore on, and the
sun beat down more fiercely, life on board became less agreeable. To
keep out the penetrating coal dust all the ports were closed, and, with
the thermometer at 90°, the air below was stifling, and the passengers
generally preferred to remain on deck, and breathe the hot air mixed
with the coal dust that arose from the open bunkers.
I offered two of the boatmen who hung about the ship three milreis if
they would land on an uninhabited part of the bay, which I pointed
out to them, and collect for me every plant they found growing, and I
was well pleased when, after two or three hours, they returned with a
respectable bundle of green foliage. Under the vigilant eyes of the
officers of health the specimens were hauled up to the deck, while the
three dollars were thrown into the boat. It is remarkable that coin is
nowhere supposed to convey contagion.
When I came to examine it, I found to my disgust that the bouquet
included only the leaves of two species, with no trace of flower or
fruit. One was most probably _Nicotiana glauca_, introduced from
tropical America; the other a leguminous shrub, possibly a _Cassia_,
but quite uncertain.
The rest of the passengers spent most of the day in bargaining with the
hucksters who flocked round the ship. Ornaments made from palm leaves,
sweetmeats of very suspicious appearance, photographs, and tobacco in
various forms, were the chief articles of traffic, and the main object
seemed to be to prolong the chaffering and bargaining over each article
so as to kill as much time as possible. More attractive in appearance
were the tropical fruits, of which those suitable to a dry climate
grow here in perfection. In spite of persevering efforts, I have never
developed much appreciation of the banana as an article of diet, but I
thought those obtained here much the best that I have anywhere eaten.
[_ATLANTIC TRADE WINDS._]
General satisfaction was felt when, the work of coaling being finished,
the ship was again in motion, with her head set towards Europe. On
returning to the channel between the islands, and still more when we
had got well out to sea, we encountered a rather strong breeze right
ahead, which with varying force continued for the next four days. This
was, of course, the regular trade-wind of the North Atlantic, and had
the agreeable effect of lowering the temperature, which at once fell
to 78°. Along with the trade-wind, the sea-current apparently travels
in the same direction. It is certain that the temperature of the water
was here much lower. Before reaching St. Vincent we found it between
80° and 81° Fahr., while after leaving the islands it had fallen to
74°. This temperature remained nearly constant for three days, but
on the evening of the 9th, in about 27° north latitude, we abruptly
encountered another current of still cooler water, in which the
thermometer fell to 69°.
The force of the wind never, I think, exceeded what seamen describe
as a fresh breeze, but it sufficed to cause at times considerable
disturbance of the surface; and on the afternoon of the 6th we shipped
some heavy seas, so that it was found expedient to slacken speed for a
time.
I have alluded in a former page to the ordinary observation that in the
track of the trade-winds the breeze usually falls off about sunset.
It is more difficult to account for the opposite phenomenon, which we
experienced on three successive evenings from the 7th to the 9th of
August, when the force of the wind increased in a marked degree after
nightfall.
I was also struck by the fact that the temperature of the air
throughout the voyage from St. Vincent to the mouth of the Tagus seemed
to be unaffected either by the varying force of the wind or by the fall
in surface-temperature of the sea, to which I have above referred.
On board ship in clear weather it is very difficult to ascertain the
true shade temperature when the sun is much above the horizon, but the
observations made at sunrise and after nightfall from the evening of
the 5th to the morning of the 11th varied very slightly, the utmost
range being from 77·5° to 73°.
Some points in the Canary Islands are often visible in the voyage from
Brazil to Europe, especially the lofty peak of Palma; but we passed
this part of the course at night, and nothing was seen. As we drew near
to Europe, the wind, through keeping the same direction, gradually fell
off to a gentle breeze, and the surface of the water became glassy
smooth, heaving gently in long undulations. The relative effect of
smooth or rough water on the speed of steamers is remarkable, and was
shown by the fact that during the twenty-four hours ending at noon on
the 11th of August the _Tagus_ accomplished a run of 295 knots, while
three days before, with only a gentle breeze but rougher water, the run
to noon was only 240 knots.
[_THE TOWER OF BELEM._]
Early in the afternoon of the 11th, the Rock of Lisbon at the mouth
of the Tagus was distinctly visible, and we slowly entered the river
and cast anchor at the quarantine station below Belem. Our captain,
after the experience of St. Vincent, did not expect to obtain pratique
at Lisbon, and with more or less grumbling the passengers had made up
their minds to remain on board, when, after a long deliberation, the
unexpected news, “admitted to pratique,” was rapidly spread through
the ship, and we moved up to the anchorage opposite the picturesque
old tower of Belem, which the true mariner must always regard as one
of his holy places. It marks the spot wherefrom Vasco de Gama and his
companions, after a night spent in prayer in the adjoining chapel,
embarked on their memorable voyage, and here, after years of anxious
uncertainty, King Manuel greeted the survivors on their return to their
country.
The sun was sinking when such passengers as wished to see something
of Lisbon took the opportunity for going ashore, while others, like
myself, preferred to remain on board. Hoping to receive letters at
the post-office, I landed early next morning, and found a tramcar to
carry me to the centre of the town. Early hours are not in much honour
at Lisbon. I found the post-office closed, and, after several vain
efforts, was informed that letters could not be delivered until ten
o’clock, the precise hour fixed for our departure from the anchorage at
Belem.
The voyage from Lisbon along the coasts of Portugal and Galicia is
usually enjoyed, even by fair-weather sailors. The case is often
otherwise with the Bay of Biscay, but on this occasion there was
nothing of which the most fastidious could complain. I have sometimes
doubted whether injustice has not been done to that much-abused bay,
which, in truth, is not rightly so called by those bound from the north
to the coast of Portugal. It is simply a part of the Atlantic Ocean,
adjoining the coast of Europe between latitudes 43° 46′ and 48° 28′.
I have not been able to ascertain that the wind blows harder, or that
the sea runs higher there than elsewhere in the same latitudes, and
am inclined to rank the prejudice against that particular tract of
sea-water among vulgar errors.
The adventurer who has attempted to open up a trade with some distant
region is accustomed, as he returns home, to count up the profits of
his expedition; and in somewhat the same spirit the man who pursues
natural knowledge can scarcely fail to take stock of the results of a
journey. It is his happy privilege to reckon up none but gains, and
those of a kind that bring abiding satisfaction. He may feel some
regret that outer circumstance or his own shortcoming have allowed
opportunities to escape, and lessened the store that he has been able
to accumulate; but as for the positive drawbacks, which seemed but
trivial at the time, they absolutely disappear in the recollection
of his experiences. Thinking of these things as the journey drew to
a close, I could not help feeling how great are the rewards that a
traveller reaps, even irrespective of anything he may learn, or of the
suggestions to thought that a voyage of this kind cannot fail to bear
with it. How much is life made fuller and richer by the stock of images
laid up in the marvellous storehouse of the brain, to be summoned, one
knows not when or how, by some hidden train of association--shifting
scenes that serve to beautify many a common and prosaic moment of life!
[_PSEUDO-PESSIMISM._]
Often during this return voyage my thoughts recurred to an article in
some periodical lent to me by my kind friends at Petropolis, wherein
the writer, with seeming gravity, discussed the question _whether life
is worth living_. My first impression, as I well remember, was somewhat
contemptuous pity for the man whose mind could be so profoundly
diseased as even to ask such a question, as for a soldier who, with
the trumpet-call sounding in his ear, should stop to inquire whether
the battle was worth fighting. When one remembers how full life is of
appeals to the active faculties of man, and how the exertion of each of
these brings its correlative satisfaction; how the world, in the first
place, needs the daily labour of the majority of our race; how much
there is yet to be learned, and how much to be taught to the ignorant;
what constant demand there is for the spirit of sympathy to alleviate
suffering in our fellows; how much beauty exists to be enjoyed, and, it
may be, to be brought home to others;--one is tempted to ask if the man
who halts to discuss whether life is worth living can have a mind to
care for truth, or a heart to feel for others, or a soul accessible to
the sense of beauty.
Recurring to the subject, as I sometimes did during the homeward
voyage, it seemed to me that I had perhaps treated the matter too
seriously, and that the article I had read was an elaborate hoax,
by which the writer, while in truth laughing at his readers, sought
merely to astonish and to gain repute as an original thinker. However
the fact may be, when taken in connection with the shallow pessimism
which, through various channels, has of late filtered into much modern
literature, there does appear to be some real danger that the disease
may spread among the weaker portion of the young generation. A new
fashion, however absurd or mischievous, is sure to have attractions
for the feebler forms of human vanity. It is true that there is
little danger that the genuine doctrine will spread widely, but the
mere masquerade of pessimism may do unimagined mischief. The better
instincts of man’s nature are not so firmly rooted that we should wish
to see the spread of any influence that directly allies itself with his
selfish and cowardly tendencies.
To any young man who has been touched by the contagion of such
doctrines, I should recommend a journey long enough and distant enough
to bring him into contact with new and varied aspects of nature and of
human society. Removed from the daily round of monotonous occupation,
or, far worse, of monotonous idleness, life is thus presented in larger
and truer proportions, and in a nature not quite worthless some chord
must be touched that will stir the springs of healthy action. If there
be in truth such beings as genuine and incurable pessimists, the stern
believer in progress will be tempted to say that the sooner they carry
out their doctrine to its logical result the better it will be for the
race. Their continued existence, where it is not merely useless, must
be altogether a mischief to their fellow-creatures.
[_RETURN TO ENGLAND._]
On the morning of the 16th of August, all but completing five months
since I quitted her shores, the coast of England was dimly descried
amid gusts of cold wind and showers of drizzling rain. My winter
experiences in the Straits of Magellan were forcibly recalled to my
mind, and I felt some partial satisfaction in the seeming confirmation
of the conclusion which I had already reached--that the physical
differences between the conditions of life in the northern and southern
hemispheres are not nearly so great as has generally been supposed.
APPENDIX A.
ON THE FALL OF TEMPERATURE IN ASCENDING TO HEIGHTS ABOVE THE SEA-LEVEL.
The remarkable features of the climate of Western Peru referred to in
the text seem to me to admit of a partial explanation from the local
conditions affecting that region. The most important of these are the
prevalence of a relatively cold oceanic current, and of accompanying
southerly breezes along the Peruvian coast. These not only directly
affect the temperature of the air and the soil in the coast-zone, but,
by causing fogs throughout a considerable part of the year, intercept
a large share of solar radiation. It has been found in Northern Chili,
some fifteen degrees farther south than Lima, but under similar
climatal conditions, that, although the land rises rather rapidly in
receding from the coast, the mean temperature increases with increasing
height for a considerable distance. It is stated on good authority[49]
that at Potrero Grande, a place about fifty miles distant, and 850
metres above the sea, the mean annual temperature is higher by 2·5° C.
than at Copiapò, or at the adjoining port of Caldera. It is probable
that in the valley of the Rimac the mean temperature at a height of
1000 metres is at least as high as it is at Lima. Taking the mean
temperature of the lower station at 19·2° C., and that of Chicla at
12·2° C., that would give a fall of 7° for a difference of level of
2724 metres, or an average fall of 1° for 387 metres, instead of 1° for
512 metres, as given in the text.
A further peculiarity in the climate, which tends to diminish
below the normal amount the rate of decrease of temperature, is
the comparative absence of strong winds, and the feebleness of the
sea-breezes which are usually so conspicuous in the tropics. For
reasons that will be further noticed, the fall in temperature in
ascending mountain ranges is largely due to currents of air carried
up from the lower region. In mountain countries an air-current,
encountering a range transverse to its own direction, is mechanically
forced to rise along the slopes, and thus raises large masses of air to
a higher level; the same effect in a less degree occurs with isolated
peaks. But in the Peruvian Andes, as well as in many other parts of the
great range, although storms arise from local causes on the plateau,
westerly winds from the ocean are infrequent and feeble; and the
sea-breezes, due to the heating of the soil by day, much less sensible
than usual in warm countries.
Making full allowance for the operation of the two causes here
specified, it yet appears that the difference of temperature between
the coast and the higher slopes of the Peruvian Andes is exceptionally
small. It is not merely due to the abnormal cooling of the coast-zone,
but to the exceptionally high temperature found in the zone ranging
from 3500 to 4000 metres. I should not have attached much importance to
the few observations of the thermometer that I was able to make during
a hurried visit, if the conclusion which they suggest had not been
strongly confirmed by the character and aspect of the vegetation.
When I found that the table given by Humboldt, which has been
copied and adopted by so many writers on physics, in which the mean
temperature at a height of 2000 toises, or 3898 metres, in the
Andes of Ecuador, close to the equator, is set down at 7°, while at
Chicla, thirteen degrees of latitude south, at a height less only by
174 metres, there is reason to believe that we find a mean annual
temperature of not less than 12°, I was led to enter more fully into
the subject.
The result of somewhat careful study has been to convince me that,
while the physical principles involved in the attempt to discover
the vertical distribution of temperature in the atmosphere prove
the problem to be one of extreme complexity, the results hitherto
obtained from observation are altogether insufficient to guide us to an
approximate law of distribution. I may remark that the problem has not
merely a general interest in connection with the physics of the globe,
but has a direct bearing on two practical applications of science. The
observations of the astronomer and the surveyor require a knowledge of
the amount of atmospheric refraction, by which the apparent positions
of the heavenly bodies, or of distant terrestrial objects, are made to
differ from the true direction; and to determine accurately the amount
of refraction we should know the temperature of the successive strata
of air intervening between the observer and the object. In determining
heights by means of the barometer, or any other instrument for
measuring the pressure of the air, it is equally necessary for accuracy
to know the variations of temperature in the space between the higher
and the lower station.
Three different opinions have prevailed among physicists as to the law,
or supposed law, of the rate of variation of temperature in ascending
from the sea-level. The simplest supposition, and the most convenient
in practice, is that the fall of temperature is directly proportional
to the height, and this has been adopted in several physical treatises.
In English works the rate has been stated at a fall of 1° Fahr. for
300 feet of ascent, and by French writers the not quite equivalent
rate of 1° C. for 170 metres has been adopted. The formula proposed by
Laplace for the determination of heights from barometric observations,
which has been very generally adopted by travellers and men of science,
implicitly assumes that the rate of decrease of temperature is more
rapid as we ascend to the higher regions than it is near the sea-level,
and this opinion was explicitly affirmed by Biot in his memoirs
on atmospheric refraction. A third hypothesis may be said to have
originated when, in 1862, Mr. Glaisher made his report of the results
of the famous balloon ascents effected by him and Mr. Coxwell,[50]
and among others exhibited a table showing the average decline of
temperature corresponding to each successive thousand feet increase of
elevation from the sea-level to a height of 29,000 English feet.
As Mr. Glaisher’s tables showed a gradual decline in the rate of fall
of temperature with increasing height, they clearly did not accord
with the ordinary assumption of an uniform rate, and still less with
the hypothesis of Laplace and Biot. In February, 1864, Count Paul de
St. Robert, of Turin, communicated to the _Philosophical Magazine_ a
short paper, in which he showed the incompatibility of Mr. Glaisher’s
results with the ordinary formulæ for the reduction of barometric
observations, and proposed a new formula based on a law of decrement
of heat based upon Mr. Glaisher’s tables. In the following June, M. de
St. Robert published in the same journal a further paper, in which,
still accepting Mr. Glaisher’s results as accurate, he investigated the
subject in a masterly manner, as well with reference to the measurement
of heights, as in its connection with the determination of the amount
of atmospheric refraction. The formula proposed by M. de St. Robert,
and the tables subsequently published by him for its adaptation to use,
appearing to be at once the most accurate and the most convenient,
have been adopted by myself and by many other travellers;[51] but it
is evident that their value depends on the correctness of the results,
above referred to, deduced by Mr. Glaisher, and their conformity with
observation in mountain countries.
Before we inquire into the conclusions to be drawn from observation,
it may be well to point out how incomplete is our knowledge of the
physical agencies which regulate the distribution of temperature in the
atmosphere.
The primary source of temperature is solar radiation, and its effect
at any given point on the earth’s surface depends on the absolute
amount of heating power in the sun’s rays, irrespective of absorption,
commonly designated the _solar constant_, and on the proportion of heat
which is lost by absorption in passing through the atmosphere. The
temperature of the air at any point will, in the first place, depend
on the amount of solar radiation and of heat radiated from terrestrial
objects directly absorbed, and next on the heating of the strata near
the surface by convection. The amount of heat received from the sun,
directly or indirectly, varies of course with the sun’s declination at
the time, and the length of the day at the place of observation. When
the sun is below the horizon the air loses heat by radiation, and still
more, in the strata near the surface, by convection to surfaces cooled
by radiation.
It was until lately believed that the experiments of Herschel and
Pouillet had given an approximate measure of the absolute intensity of
solar radiation, and that the proportion absorbed by the atmosphere
at the sea-level at a vertical incidence might be estimated at about
one-fourth of the whole. It is not too much to say that the recent
researches of Mr. Langley, especially those detailed in his _Report of
the Mount Whitney expedition_,[52] have completely revolutionized this
department of physics. It now appears that the true value of the solar
constant is not much less than twice as great as the previous estimate,
and that rather more than one-third is absorbed by the atmosphere
before reaching the sea-level. Mr. Langley has further proved that the
absorptive action of the atmosphere varies with the wave-length of
the rays, and that, omitting the “cold bands” which correspond to the
dark bands in the visible spectrum, it diminishes as the wave-length
increases. It further appears highly probable that the larger part of
the absorptive action of the atmosphere is due to the aqueous vapour,
the carbonic acid gas, and the minute floating particles of solid
matter, which are present in variable proportions. Allowing for the
probable extension of our knowledge by further research, it is yet
evident that, even if we had not to take into account the further
elements of the problem next to be specified, the distribution of heat
in the atmosphere, as dependent on solar radiation, is a question of
extreme complexity.
The action of winds has an important effect in modifying the
temperature of the air. It is not possible to draw a distinct line
between the great air-currents, which affect large areas, and slight
breezes, depending on local causes, and limited to the lower strata of
the atmosphere; but in relation to the present subject it is necessary
to distinguish between them. There is a general circulation in the
aërial envelope covering the earth, caused by unequal heating of
different parts of the surface. Heated air rises in the equatorial
zone, and its place is filled by currents from the temperate and
subtropical zones. The heated air from the equator flows at first as
an upper current towards the poles, but as it gradually loses its
high temperature, it becomes mixed with the currents setting from the
poles towards the equator, causing the atmospheric disturbances and
variable winds characteristic of the cooler temperate zones. As a
rule, bodies of air of different temperatures do not very quickly mix,
but tend to arrange themselves in layers or strata in which masses
of unequal temperature are superposed. It is obvious that in such a
condition, where a layer of colder air lies between two having a higher
temperature, the whole cannot be in a state of equilibrium. But in
nature we constantly find that equilibrium is never attained. There is
a continual tendency towards equilibrium, along with fresh disturbances
which alter the conditions.
As Professor Stokes remarks in a letter on this subject with which he
favoured me, “to know the temperature of the successive strata as we
ascend in a balloon, we should know the biographies of the different
strata.” Those which are now superposed may have been hundreds of miles
apart twenty-four hours before. It follows that without a knowledge
of the course and velocity of the higher currents existing in the
atmosphere, we cannot expect to learn the vertical distribution of
temperature.
Apart from the effects of the great movements of the air, there is
another effect of air-currents to be considered, which tends especially
to modify the temperature found at or near the earth’s surface. The
heating of the surface by day, and the cooling by night, determine
the existence of local currents of ascending or descending air. In
rising, the air encounters diminished pressure, and therefore expands,
and in so doing overcomes resistance. The molecular work involved in
dilatation is performed at the expense of the other form of molecular
work which we call heat. In other words, the air in ascending loses
heat. It is found that the amount of decrement of temperature due to
the ascent of a body of air is nearly exactly 1° C. for 100 metres.
As a general rule, ascending currents arise from the surfaces exposed
to the sun during the day, and must largely contribute to produce the
rapid decrement of heat which is found in the lower strata near the
surface, as compared with the rate of change in the higher regions;
but it will be obvious that the amount of effect produced by this cause
is subject to continual variation from changes in local conditions.
The nature of the soil, the extent and character of the vegetation,
the form of the surface, are all elements which modify the amount of
disturbance in the equilibrium of the surrounding atmosphere. As above
remarked, in discussing the climate of Western Peru, prevailing winds
which impinge upon a range of mountains may indirectly affect the
temperature of the higher region by mechanically forcing masses of air
to rise along the slopes, and ultimately, by expansion, to be cooled
much below the temperature which they possessed when they originally
flowed against the slopes.
One of the most important agencies affecting the distribution of
temperature in the atmosphere arises from the presence of aqueous
vapour. In its invisible condition it affects the absorptive power of
the air on the solar rays, and, when condensed in the form of cloud,
it acts as a screen, intercepting most of the calorific rays which
would otherwise reach the earth. But it is especially through the
large amount of heat consumed in converting water into vapour, and
set free when vapour returns to the fluid state, that the temperature
of the air is largely modified. When we consider that in converting
a given volume--say, one cubic metre--of water into vapour, enough
heat is consumed to lower about 1,650,000 cubic metres of air by 1°
C. in temperature, and that the same amount of heat is liberated when
the vapour so produced returns to the liquid state, we perceive how
powerfully the ordinary processes of evaporation and condensation must
affect the temperature of the air.
It is needless to analyze further the several agencies which, sometimes
co-operating, and sometimes in mutual opposition, determine the
vertical distribution of temperature in the atmosphere. It is but
too obvious that no approach to uniformity can be expected, and it
might even be anticipated that any approximation to a regular law of
distribution that should be found under one set of conditions--as, for
instance, in serene weather by day--would be altogether inapplicable
under different conditions, such as exist in stormy weather, or by
night.
The need for practical application of some empirical rule, or law, of
vertical distribution has made it necessary to appeal to the results
of observation, and for this object the only existing materials are to
be found in the records of balloon ascents, and in the observations
made on high mountains. In balloon ascents the temperature at any
considerable height is free from the disturbances caused by the
vicinity of the earth’s surface, and the results might be expected
to contribute to the more accurate determination of the amount
of atmospheric refraction. For the measurement of heights by the
barometer, it would appear safer to rely on such information as may be
gleaned from mountain observations.
Of balloon ascents by far the most important are those achieved in
1862 by Messrs. Glaisher and Coxwell, to which I have referred in a
preceding page. Mr. Glaisher has given in his report a full record of
the actual observations made in the course of his eight ascents, and
has explained the processes by which he constructed the successive
tables, from which he deduced as the final result a continuous decline
(unbroken save in a single instance) in the rate of decrement of
temperature found in passing through each successive zone of 1000 feet,
in ascending from the sea-level to a height of 29,000 English feet.
I am not aware that the processes employed by Mr. Glaisher in obtaining
these results have ever been subjected to such close scrutiny as their
importance demands, and as I have found on careful examination that
his results are not borne out by the actual observations, I am forced
to express my dissent from his conclusions. The admiration due to the
courage, skill, and perseverance displayed by Mr. Glaisher throughout
these memorable ascents will not be lessened if we should find it
necessary to modify the inferences which he has drawn from them.
The full discussion of Mr. Glaisher’s observations involves an
inconvenient amount of detail, and such readers as may be disposed to
enter more fully into the subject I must refer to an article in the
_London, Edinburgh, and Dublin Philosophical Magazine_.
The general conclusions to which I have arrived from the observations
made under a clear or partially clear sky is, that the average results
show a rapid fall of temperature in the zone extending to about 5000
feet, or 1500 metres, above the earth’s surface, and that, within that
limit, the rate of fall diminishes as the height increases. Above
the height specified the observations prove that in each ascent the
balloon passed through successive strata of air whose temperature
varied in a completely irregular manner, the fall of temperature being
sometimes very rapid for an ascent of a few hundred feet, and sometimes
very slight in a much longer interval. In each of the higher ascents
we even find instances in which the thermometer rose in ascending
from a lower to a higher station, reversing the ordinary progression.
These alternations occurred at various heights from 5000 to 25,000
or 26,000 feet above the sea-level.[53] It seems to me very doubtful
whether any safe conclusions can be drawn from averages deduced from
separate series of observations so discordant, but, in any case, I may
confidently assert that the results of actual observations do not bear
out the conclusions deduced by Mr. Glaisher.
I desire further to point out that these balloon ascents were all
executed by day, in summer, and in weather as serene as can ordinarily
be found in our climate. If they did authorize us to derive from them
an empirical law regulating the vertical distribution of temperature,
this might, at the best, serve to approximate to the true amount of
atmospheric refraction found by day in geodetical observations, but
would be no guide to the conditions obtaining by night, which are those
important to the astronomer.
Mr. Glaisher has not failed to notice the great difference shown by the
observations made when the sky was overclouded as compared with those
under a clear or partially clear sky, and has given a table showing
that the mean results up to a height of 4000 feet above the sea show
a nearly uniform decline of 1° Fahr. for each 244 feet at ascent. The
numerical results of observations made under, or amidst, cloud appear
to me of no practical value, as they depend upon conditions which are
subject to constant variation.
If it be true that observations in balloon ascents, which are free from
the disturbances caused by the vicinity of the earth’s surface, have
hitherto failed to lead to any general results indicating a normal
rate of decrease of temperature with increasing elevation, it could
scarcely be hoped that observations on mountains should contribute
farther to enlighten us. From what has been already said, it is
apparent that the fact that the place of observation is close to the
surface causes disturbances the nature and amount of which must vary
with each particular spot, and with the season and the condition of the
atmosphere at the moment of observation.
The intensity of solar radiation increases rapidly with increasing
elevation,[54] so that when the sky is clear surfaces exposed to the
sun are heated much above the normal temperature. Owing to its slight
absorptive power the free atmosphere is little affected; but the strata
nearest the surface are heated by convection, while a contrary effect
follows when the surface is no longer exposed to the sun, and radiates
freely to the sky.
The air in mountain countries is rarely at rest. Even when there is no
sensible breeze, the unequal heating of the surface causes ascending
and descending currents, which lose or gain heat by expansion or
contraction. More commonly winds are experienced which, by impinging on
the inclined surfaces, force bodies of air to higher elevations, and
thereby directly cause a fall of temperature.
All these causes of disturbance are complicated by the action of
aqueous vapour, which, in most mountain countries, is supplied from the
surface, as well as borne upwards by ascending currents. Besides the
effect of raising the temperature where condensation takes place, and
lowering it where clouds are dissolved in strata of dry air, the amount
of aqueous vapour present at a given place affects the intensity of
solar radiation, and the consequent amount of heating of the surface.
In spite of these obstacles to the attainment of accurate numerical
results from which to infer the distribution of temperature in the
atmosphere, we are yet, for the larger part of the earth, forced to
rely on mountain observations as the only available source from which
any indications of a law of distribution can be gleaned. Balloon
observations have hitherto, so far as I know, been confined to a few
places in Europe; and, even if the results were more conclusive than
they have hitherto been, we should not be entitled to infer that they
held good for all parts of the earth. In countries where the course
of the seasons is more uniform, and the direction and force of the
winds less inconstant, it might be expected that the distribution of
temperature would exhibit some nearer approach to uniformity; and the
possibility of making observations at mountain stations by night might
enable us to form some conjecture as to a condition of the atmosphere
very different from that which obtains when the influence of the sun is
present.
It cannot be said that the observations hitherto made on mountains have
done as much as they might do, if properly conducted, to contribute to
our knowledge; but a few leading facts may be derived from them, and it
is worth while to point them out.
The most important of these is, perhaps, the influence of plateaux of
elevated land in raising the temperature of the adjacent air. This is
established by observation in all parts of the world, and it would
appear that the rapid fall of temperature in the strata near the
surface which is found at or near the level of the sea, is equally
marked when we ascend from a plateau to an isolated summit. Both these
conclusions, however, apply only to observations made in the summer of
temperate regions, or in the warmer parts of the earth. Apart from this
effect of a relatively heated surface which appears to extend above the
surface to a height of about 1500 metres, or, in round numbers, 5000
English feet, mountain observations give but slight confirmation to the
belief that the rate of decrease of temperature, in normal conditions
of the atmosphere, diminishes as the elevation increases.
In endeavouring to use the available materials one difficulty arises
from the fact that, in comparing the temperature of the upper with the
lower stations, observers have rarely been supplied with simultaneous
observations at the lower station, or that, when these have been
available, the distance has been so great that the results throw
little light on the probable condition of a vertical column of air
near the higher station. In parts of the world where the daily range
of temperature near the coast is very slight, we may with small risk
of error use the mean temperature of the season at the lower station
as the element of comparison, and, in places near the equator, the
mean annual temperature. For this reason, observations in the Andes of
Ecuador, Peru, and Bolivia present great advantages, and I think it may
be useful to discuss the results so far as they are now available.
It is scarcely necessary to examine critically the results of
the earlier explorations. Humboldt has given in the “Recueil des
Observations Astronomiques,” etc., and in the “Memoires de la Société
d’Arcueil,” vol. iii. p. 579, and elsewhere, the observations made by
himself in Mexico, Colombia, and Peru, and also those of Caldas and
Boussingault, and has derived from them a table which, with more or
less modification, has been adopted in many physical treatises. It
exhibits the mean differences of temperature found in successive zones
differing in height by 500 toises, the interval corresponding to 974·6
metres, or very nearly 3000 English feet.
----------+-----------------+------------------+--------------------
Height in |Mean temperature.|Number of metres |Number of metres
toises. | |corresponding to a|corresponding to a
| |fall of 1°C. from |fall of 1°C. between
| |the sea-level. |successive zones of
| | |500 toises.
----------+-----------------+------------------+--------------------
Sea-level | 27·5 | -- | --
500 | 21·8 | 171 | 171
1000 | 18·4 | 216 | 287
1500 | 14·3 | 221 | 238
2000 | 7·0 | 190 | 133
2500 | 1·5 | 187 | 177
----------+-----------------+------------------+--------------------
The first remark to be made about this table is that the observations
on which it is founded are not properly comparable, being partly single
observations made during an ascent, and partly the mean of numerous
observations made at certain places, such as Mexico, Quito, etc. It may
further be remarked that many of the heights determined by Humboldt
have been considerably modified by the results obtained by more recent
travellers, and cannot now be regarded as correct. The influence of
plateaux is, however, very apparent, as nearly all the observations
from which the estimated temperatures for 1000 and 1500 toises were
derived were made at places situated on open elevated valleys or
plateaux. At the utmost, the results can be regarded merely as rough
approximations to the truth.
By far the most important available observations in the Andes are those
of Mr. Whymper, made during his remarkable explorations in 1880; but,
unfortunately, the details have not yet been given to the world, and,
in endeavouring to make use of them, I have been forced to content
myself with the brief summary published in the _Proceedings of the
Royal Geographical Society_ for 1881. Mr. Whymper was able to secure
a register of the temperatures observed at Guayaquil during his stay
in Ecuador, which will doubtless be published along with the record
of his own observations; but it does not appear that he was able to
obtain observations at Quito during his ascents to the higher peaks;
and it seems that, in comparing the temperatures for the purpose of
reducing his barometrical observations, he was forced to assume for
Quito a mean temperature of 57·9 Fahr., or 14·4 C., obtained from a
series of thermometric observations made during his stay at that place.
There is reason to believe that the daily range of the thermometer at
Quito is very moderate; and at the equator the differences of season
are comparatively slight; nevertheless, the absence of simultaneous
observations at that place diminishes the value of the results shown
in the following table, in which Mr. Whymper’s results are reduced to
metrical measure.
I have adopted the heights determined by Mr. Whymper as those deserving
most confidence. They agree very well with those published by MM.
Reiss and Stubel, so that the limits of error from this cause are
inconsiderable. I have also adopted the height assigned to Quito--9350
feet, or 2848 metres. Where Mr. Whymper remained long enough on any
summit to observe notable variations in the reading of the thermometer,
I have taken the mean of the observed temperatures; but I have entered
separately the results of the ascents of Chimborazo, one being made in
January, the other in July, and in a separate line I have entered the
mean results of the two.
In the following table I have entered in the first column the names
of the peaks ascended by Mr. Whymper; in the second, the height of
each as given by him; in the third, the observed temperature in
degrees Centigrade; in the fourth, the difference between the observed
temperature and 27° C.--that assumed for Guayaquil; in the fifth, the
average number of metres corresponding to a fall of 1° C. in rising
from the sea-level to the higher station; in the sixth, the difference
between the observed temperatures and that assumed for Quito--14·4°;
and in the seventh, the average number of metres corresponding to a
fall of 1° C. in rising from Quito to the higher station. It is obvious
that the more rapid the fall the less will be the number in columns 5
and 7.
Key:
A: Name of Mountain.
B: Height above sea-level.
C: Observed temperature.
D: Difference of temperature at sea-level.
E: Average number of metres for fall of 1° C. from sea-level.
F: Difference of temperature at Quito.
G: Average number of metres for fall of 1° C. from Quito.
---+---------------------+------+--------+-------+-------+-------+------
| A | B | C | D | E | F | G
---+---------------------+------+--------+-------+-------+-------+------
1 | Chimborazo (Jan.) | 6253 | -6·1 | 33·1 | 189 | 20·5 | 166
2 | Chimborazo (July) | 6253 | -8·06 | 35·06 | 178 | 22·46 | 151
3 | Mean of (1) and (2) | 6253 | -7·08 | 34·08 | 183·5 | 21·48 | 158·5
4 | Cotopaxi | 5959 | -8·4 | 35·4 | 168 | 22·8 | 136·5
5 | Antisana | 5870 | +11·1 | 15·9 | 369 | 3·3 | 916
6 | Cayambe | 5852 | +2·5 | 24·5 | 239 | 11·9 | 252
7 | Cahihuairazo | 5035 | +4·44 | 22·56 | 223 | 9·96 | 220
8 | Cotocachi | 4965 | +2·2 | 24·8 | 202 | 12·2 | 173·5
9 | Pichincha | 4851 | +7·77 | 19·23 | 255 | 6·63 | 302
10 | Corazon | 4837 | +4·44 | 22·56 | 214 | 9·96 | 200
11 | Sara Urcu | 4718 | +10·0 | 17·00 | 284 | 4·4 | 425
---+---------------------+------+--------+-------+-------+-------+------
It will at once be seen that the temperatures observed on Antisana,
Pichincha, and Sara Urcu were altogether exceptional, probably due
to rapid condensation of vapour; and these may best be excluded from
any discussion of the general results. The temperatures noted in the
second ascent of Chimborazo were probably below the mean, or at least
below the mean for the hours at which most of the other observations
were made. But, as opinions may differ on that point, I have also given
below the results of comparison with the mean for the two ascents of
Chimborazo. For a similar reason I regard the figures for Cotopaxi,
where Mr. Whymper remained for twenty-six hours on the summit, as
giving too low a temperature, while that observed on Cayambe is
certainly too high. The mean result for these two summits is probably a
near approximation to the average for that height.
In attempting to draw conclusions from the above table, we must
first remark that, in consequence of its position on a plateau, the
temperature of Quito is considerably higher than it would probably be
if the higher peaks descended with an uniform slope to the sea-level.
The difference between the means for that place and Guayaquil is
only 12·6° C.; whereas, on the supposition of an uniform decrease in
ascending from the sea-level, it should be 14·2°, and still greater if
we supposed that the rate of fall of temperature gradually diminishes
as the elevation increases. Omitting altogether the results for numbers
5, 9, and 11 in the above table, we perceive that the observations fall
into three groups: (1) those for Chimborazo, at 6253 metres; (2) those
for Cotopaxi and Cayambe, with a mean height of 5905 metres; (3) those
for Cahihuairazo, Cotocachi, and Corazon, whose mean height is 4950
metres. To these it may be well to compare the mean of the results for
the entire series, and also the rate of decrease between the sea-level
and Quito. I shall designate observations included hereunder by numbers
corresponding to the lines in the preceding table. The number of metres
of ascent corresponding to a fall of 1° C. gives the most convenient
measure of the rate of decrease.
Key:
A: Mean height.
B: Difference of temperature at sea-level.
C: Metres for fall of 1° C. from sea-level.
D: Difference of temperature at Quito.
E: Metres for fall of 1° C. from Quito.
------------------------------+--------+-------+-------+-------+------
| A | B | C | D | E
------------------------------+--------+-------+-------+-------+------
Quito | 2848 | 12·6 | 226 | 0 | 0
Mean of 1, 4, 6, 7, 8, and 10 | 5483·5 | 27·19 | 201·5 | 14·59 | 180·6
” 3, 4, 6, 7, 8, and 10 | 5483·5 | 27·35 | 200·5 | 14·75 | 178·7
” 7, 8, and 10 | 4946 | 23·37 | 212 | 10·77 | 195
” 4 and 6 | 5905 | 29·95 | 197 | 17·35 | 176
------------------------------+--------+-------+-------+-------+------
We see from this table that, in ascending from the coast to the highest
peaks of Ecuador, the average fall of the thermometer was, in round
numbers, 1° C. for every 200 metres of ascent, while in ascending from
the sea-level to the plateau of Quito the fall was proportionately
less, being at the rate of 1° C. for 226 metres. On the other hand,
the fall of temperature was more rapid in ascending from Quito to the
higher peaks. On an average of all the ascents, we may reckon the rate
of 1° for 180 metres. But it is remarkable that, taking the average of
the three peaks which rise about 2000 metres above the level of Quito,
the temperature fell only at the rate of 1° for 195 metres, while in
ascending to peaks higher by nearly 1000 metres, the rate of fall was
1° for 176 metres, and if we take the still higher summit of Chimborazo
we may reckon the rate of fall at about 1° for 160 metres.
The apparent increase in the rate of decline of temperature in the
higher region is still more clearly shown if we compare the mean of the
three peaks whose average height is 4946 metres, with that of the two
whose average height is 5905. For a difference in the mean height of
959 metres, we find an average fall of 6·58° C., or a fall of 1° for
145 metres. Taking the first ascent of Chimborazo as giving the most
probable results, we find that between this peak and the mean of the
three lower summits, with a difference in height of 1307 metres, the
difference of temperature is 9·73°, or a fall of 1° for 134 metres.
Again, comparing Chimborazo with the mean of Cotopaxi and Cayambe,
we find, for a difference of height of 348 metres, a difference of
temperature of 3·15°, or a fall of 1° for 110 metres.
I am fully aware that these observations are not numerous enough
to lead to any safe general conclusions; the comparatively high
temperatures found at the height of about 5000 metres may be due to
exceptional local conditions, such, for instance, as the ordinary
formation of clouds at about that level; but, so far as they go, the
observations tend to negative the supposition that in the tropics the
rate of decrease of temperature diminishes as we ascend to the higher
regions of the atmosphere.
MM. Reiss and Stubel made numerous observations in the Andes of Ecuador
and Peru, during a prolonged visit to that region. Lists of heights
obtained by reduction from their observations have appeared in various
German scientific periodicals, and more fully in the _American Journal
of Science_, vol. ii. pp. 268, 269; but, so far as I can ascertain,
the record of their observations of the barometer and thermometer has
never been given to the world.
In “Copernicus,” vol. iii. p. 193, _et seq._, Mr. Ralph Copeland has
published a summary of the results of a series of meteorological
observations made by him at various stations on the line of railway
connecting Mollendo on the Pacific coast with Puno in Bolivia, near
the lake of Titicaca, and also at La Paz and at Tacna. Two series
of observations were made at Vincocaya, the summit station of the
railway, 4377 metres above the sea. All the other stations are either
on elevated plateaux, or on open slopes inclining gently towards the
coast. The temperatures are partly derived from numerous observations
and partly by taking the mean of the maxima and minima, with
corrections for each station, the reasons for which are assigned by Mr.
Copeland. In most of these I am inclined to concur, but there are two
from which I am forced to dissent. In reducing Mr. Copeland’s tables to
metrical measure, I have therefore ventured to make some corrections,
which do not, however, much alter the results.
I give below the heights above the sea, in metres, with the corrected
mean temperature for each place, and the dates for each set of
observations.
-----------------+--------------+-------+----------------+------------
| | | | Mean
Places. | Latitude. |Height.| Dates of |temperature,
| | | observation. | corrected.
-----------------+--------------+-------+----------------+------------
Mollendo | 17° 2′ 54″ | 20 | July 2 | 16·7° C.
Tacna | 18° 1′ 21″ | 560 | July 7-10 | 14·2°
Arequipa Hotel | 16° 25′ 20″ | 2346 | Feb. 2-8 | 16·2°
Arequipa railway | | | |
station | ---- | 2300 | June 29-30 | 9·0°
Vincocaya, I. | 15° 53′ 56″ | 4377 |Feb. 28-March 4 | 2·83°
Vincocaya, II. | ---- | -- | June 6-27 | -2·2°
Puno, I. | 15° 50′ 2″ | 3840 |March 20-April 4| 9·2°
Puno, II. | ---- | -- |April 15-June 2 | 7·8°
La Paz | 16° 27′ 0″ | 3645 | Feb. 12-25 | 10·7°
-----------------+--------------+-------+----------------+------------
Without entering into minute details, or discussing the small
corrections for changes in the sun’s declination to be allowed for
latitude and for the dates of observation, we perceive that on the
western slope of the Cordillera the rate of decrease of temperature in
this region is much below the ordinary average. Estimating the mean
temperature of Mollendo at 22° at the beginning of February, we find
between Mollendo and Arequipa a difference of 5·8° C., or a fall in
summer of 1° for an ascent of 401 metres; while in mid-winter we obtain
a difference of 7·7°, showing that an ascent of 364 metres is necessary
to cause a fall of 1°. This abnormal condition is, no doubt, mainly
due to the exceptionally low temperature of the coast-zone. Between
Arequipa and Vincocaya we may reckon the fall of temperature on the 1st
of March at 14·2° for an ascent of 2031 metres, giving the proportion
of 1° to 143 metres; but in winter the decrease is less rapid, as we
have at the end of June a difference of about 11·5° for an ascent of
2077 metres, or about 181 metres for a fall of 1°.
A remarkable contrast is shown when we compare the temperature at
Vincocaya with that of places on the plateau surrounding the great
lake of Titicaca. From Mr. Copeland’s observations we may estimate the
mean annual temperature of Vincocaya at 1° C., that of Puno at 8·5°,
and that of La Paz at 8·8°. These figures would give a mean difference
of 7·5° for a difference in height of 537 metres between Vincocaya
and Puno, or a decrease of 1° for 72 metres. Between Vincocaya and La
Paz we have a difference of 7·8° for a difference in height of 732
metres, or a fall of 1° for 94 metres. The mean of the two comparisons
gives a fall of 1° for 83 metres, or about twice as rapid a change as
the average of the comparison between Arequipa and Vincocaya. I am
not disposed to attribute this remarkable difference of atmospheric
conditions exclusively to the influence of plateaux in raising the mean
temperature.
In my own slight experience in the Peruvian Andes, in ascending from
Chicla, at about 3700 metres, to Casapalta, at about 4200 metres, I
observed so complete and rapid a change in the character and aspect of
the vegetation as to satisfy me that the difference in the annual mean
temperature must be even greater than that observed by Mr. Copeland for
a somewhat greater difference of height between Vincocaya and Puno. It
may be that, in this comparatively dry region of the Andes, the higher
stations receive more frequent, though not copious, falls of rain or
snow, the evaporation of which maintains a constant low temperature in
the surface and the surrounding air.
In comparing observations in Peru, Bolivia, or Chili with those made
in the Andes of Ecuador, it must not be forgotten that the climatal
conditions are essentially different. Owing to the fact that in the
latter the range of the Andes is much narrower, and on one side the
main valleys descend in a nearly due easterly direction, the hot,
vapour-laden, easterly winds reach the plateaux still charged with
moisture, and at all seasons rain is frequent and abundant. Farther
south, the winds from the Atlantic have deposited the greater part
of their moisture before they arrive at the western side of the main
range, and the annual rainfall must be comparatively trifling.