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During the two ascents and descents of the Rio Negro and Vaupés in 1850–1852 I took observations with a prismatic compass, not only of the course of the canoe, but also of every visible point, hill, house, or channel between the islands, so as to be able to map this little known river. For the distances I timed our journey by a good watch, and estimated the rate of travel up or down the river, and whether paddling or sailing. With my sextant I determined several latitudes by altitudes of the sun, or of some of the fixed stars. The longitudes of Barra and of San Carlos, near the mouth of the Cassiquiare, had been determined by previous travellers, and my aim was to give a tolerable idea of the course and width of the river between these points, and to map the almost unknown river Uaupés for the first four hundred miles of its course. From these observations I made a large map to illustrate a paper which I read before the Royal Geographical Society. This map was reduced and lithographed to accompany the paper, and as it contains a good deal of information as to the nature of the country along the banks of the rivers, the isolated granite mountains and peaks, with an enlarged map of the river Uaupés, showing the position of the various cataracts I ascended, the Indian tribes that inhabit it, with some of the more important vegetable products of the surrounding forests, it is here given to illustrate this and the two preceding chapters (see p. 320). It will also be of interest to readers who possess my “Travels on the Amazon and Rio Negro," which was published before the map was available.
The great feature of this river is its enormous width, often fifteen or twenty miles, and its being so crowded with islands, all densely forest-clad and often of great extent, that for a distance of nearly five hundred miles it is only at rare intervals that the northern bank is visible from the southern, or vice verså. For the first four hundred and fifty miles of its course the country is a great forest plain, the banks mostly of alluvial clays and sands, though there are occasional patches of sandstone. Then commences the great granitic plateau of the upper river, with isolated mountains and rock-pillars, extending over the watershed to the cataracts of the Orinoko, to the mountains of Guiana, and, perhaps, in some parts up to the foot of the Andes. The other great peculiarity of the river is its dark brown, or nearly black, waters, which are yet perfectly clear and pleasant to drink. This is due, no doubt, to the greater part of the river's basin being an enormous forestcovered plain, and its chief tributaries flowing over granite rocks. It is, in fact, of the same nature as the coffee-coloured waters of our Welsh and Highland streams, which have their sources among peat-bogs. A delightful peculiarity of all these black or clear water rivers is that their shores are entirely free from mosquitoes, as is amusingly referred to in my brother's letter, already quoted in Chapter XVIII.
After my journey the river Vaupés remained unknown to the world for thirty years, when, in 1881 and 1882, Count Ermanno Stradelli, after spending two years in various parts of the Amazon valley, ascending the Purus and Jurua rivers, visited this river to beyond the first cataracts. Having fever he returned to Manaos (Barra), and joined an expedition to determine the boundary between Brazil and Venezuela through an unknown region, and descended the Rio Branco to Manaos. He then went a voyage up the Madeira river, returning home in 1884. In 1887 he again visited South America, ascending the Orinoko, passed through the Cassiquiare to the Rio Negro, and having become much interested in the rock-pictures he had met with in various parts of these rivers, he again made a voyage up the Uaupés, this time penetrating to the Jurupari cataract, which I had failed to reach, and going about a hundred miles beyond it. This last voyage was made in 1890–1891. His only objects seem to have been geographical and anthropological explorations, and he has probably explored a larger number of the great tributaries of the Amazon and Orinoko than any other European.
For a knowledge of this great traveller I am indebted to Mr. Heawood, the librarian of the Royal Geographical Society, who, in reply to my inquiry as to any ascents of the Vaupés since my journey, sent me two volumes of the Bolletino della Societa Geographica Italiana (1887 and 1900), which give, so far as he can ascertain, all that is known of Count Stradelli's work. This is most scanty. In the 1887 volume there is a very short abstract of his earlier explorations, with a portion of his journey up the Orinoko in that year. In the volume for 1900 is an article by the Count, almost entirely devoted to a description, with drawings, of all the rock inscriptions which he found in the Uaupés. These drawings are very carefully made, and are twelve in number, each representing a whole rock surface, often containing several groups of forty or fifty distinct figures. It is rather curious that several of the groups in my two plates do not appear in any of the twelve plates of Count Stradelli. Besides these drawings there are several large scale sketch-plans of the portions of the river where they were found, mostly at cataracts or rapids where there are large exposed rock surfaces. The map showing the first three cataracts well illustrates the description of them given at p. 197 of my “Travels.” But besides these sketch-plans there is a large folding map of the Uaupés, drawn by Count Stradelli from “compass” bearings during this last journey. There is no reference whatever to this map by the Count himself, except the statement on the title that it is by "compass” observations, as was mine. And as there is no reference to any determinations of longitude the distances could only have been ascertained by estimated rates of canoetravel, such as I used myself. I therefore compared the two maps with much interest, and found some discrepancies of considerable amount. His map is on a scale rather more than four times that of mine ; but my original map, now in the possession of the Geographical Society, is on a larger scale than his. His longitude of the river's mouth is 67° 5', mine being 68°, more accurate determinations having now been made than were available at the time I prepared my map, more than fifty years ago. On comparing the two maps we see at once a very close agreement in the various curves, sharp bends, loops, and other irregularities of the river's course, so that, omitting the minuter details, the two correspond very satisfactorily. But when we compare the total length of the river to my furthest point, close to the mouth of the Codiary, there is a large difference. The difference of the longitudes of these two points on the count's map is 2° 22', whereas on mine it is 3° 45'; my estimate being about 60 per cent. more than his. By measuring carefully with compasses in lengths of five miles, with a little allowance for the minuter bends, his distance is 315 miles, mine 494, mine being thus 55 per cent. more.
It is unfortunate that Count Stradelli has given us no information as to how he estimated his distances. In a river flowing through a densely wooded country, with nowhere more than a few hundred yards of clear ground on its banks, with a very crooked and twisted course, and with a current varying from being scarcely perceptible to such rapidity that a whole crew of paddlers can hardly make way against it, it is exceedingly difficult to ascertain the rate of motion in miles per hour.
Canoes of different sizes do not travel at very different rates, when each has its complement of men, and I had taken many opportunities to ascertain this rate in still water. Then, by noting the time occupied for a particular distance, say between two of the cataracts, both during the ascent and descent of the river, the mean of the two would be the time if there were no current. Making a little allowance for the load in the canoe, the number or the quality of the rowers, etc., this time multiplied by the rate of travel in still water would give the distance, This was the plan I adopted in making my map of the Uaupés. It is, of course, a mere approximation, and liable to considerable errors, but I did not think they would lead to such a large difference of distance as that between the Count's map and my own. We have no doubt erred in opposite directions, and the truth lies somewhere between us; but until some traveller takes a good chronometer up the river with a sextant for determining local time, or a telescope of sufficient size to observe eclipses of Jupiter's satellites, the true length of the river will not be settled.
In one of the latest atlases, “The Twentieth Century Citizens' Atlas,” by Bartholomew, the position of the Jurupari fall is 62 per cent. further from the mouth of the river than
on Stradelli's map, which seems to show either that some other traveller has determined the longitude, or that they consider my distances more correct than his.
Another traveller, Dr. T. Koch, only last year (1904) ascended the Vaupés to beyond the Jurupari fall, and also went up the Codiary branch, where he reached an elevated plateau. But it is not stated whether he made any observations to determine the true positions of his farthest point (The Geographical Journal, July, 1905, p. 89).
It seems probable, therefore, that the upper course of this great river for a distance of two or three hundred miles is quite unknown. But this is only one indication of the enormous area of country in the central plains of South America, which, except the banks of a few of the larger rivers, is occupied only by widely scattered tribes of Indians, and is as absolutely unknown to civilized man as any portion of the globe. From the Meta river on the north, to the Juambari and Beni rivers on the south, a distance of about twelve hundred miles, and to an equal average distance from the lower slopes of the Andes eastward, is one vast, nearly level, tropical forest, only known or utilized for a few miles from the banks of comparatively few of the rivers that everywhere permeate it. It is to be hoped that in the not remote future this grand and luxuriant country will be utilized, not for the creation of wealth for speculators, but to provide happy homes for millions of families.
As my collections had now made my name well known to the authorities of the Zoological and Entomological Societies, I received a ticket from the former, giving me admission to their gardens while I remained in England, and I was a welcome visitor at the scientific meetings of both societies, which I attended very regularly, and thus made the acquaintance of most of the London zoologists and entomologists. I also went frequently to examine the insect and bird collections in the British Museum (then in Great Russell Street), and also to the Linnean Society, and to the Kew Herbarium to consult works on botany, in order to name my palms.