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. Liais45 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. Hann46 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.47 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.