June i8, 1896] 



NATURE 



16- 



other <letails ascertained in order to facilitate the laying of the 

 cable. 



This preliminary survey took place in October of last year 

 during the hottest season, when the river was at its lowest ; 

 while the cable was laid during January and February of this 

 year, when the rainy season had commenced and the river was 

 rising. 



It is extremely difficult to realise the true proportions of this 

 river, but the subjoined comparative table, in which the dimensions 

 of the principal rivers of the various continents are contrasted 

 with those of the Amazon, will help to show the importance of 

 this great system of natural waterways. 



With several other large rivers the .\inazon shares the fate 

 that its name changes several times durinj; its long course, and 

 that at various times diflferent affluents base been considered to 

 be the true source of the main stream. 



-Most geographers, however, regard tlie Maraiion as the 

 principal river, a branch of which, called Tunguragua, ri.ses in 

 Lake Lauric<x:ha in I'eru in lo' 30' S. lat., and 76" 10' W. long. ; 

 although the Ucayale, where it unites with the Marafion at 

 Xauta (4° S. lat., 73' W. long), is quite as important as the 

 Maraiion. 



1 43001 



(i) To source of Mi 



(2) .\t Saratoff. 



(3) Exclusive of tributaries. 



(4) At Teddington. 



(5) To source of .'\purimac 3415 miles. 



(6) According to Dr. John Murray. 



(7) .\ccording to Dar-by, the American hydrographer. 

 .According to Encyc. Bfitt. 



Area of fVreat Britain and Ireland 120,626 



,, British India 1,560,160 



., Brazil ... ... ... ... ... ... " ... 3,219,000 



,, Europe ... 3,790,000 



If the greatest distance from the mouth is to decide the ques- 

 tion, then the source of the .\purimac, an affluent of the Ucayale, 

 can lay claim to being the origin of the .\mazon, rising in Peru 

 in 16° .S. lat., and 72" W. long. 



Along the whole course of the Amazon, commencing at the 

 foot of the .\ndes, a network of Lslands and canals is formed on 

 both sides of the river, as the whole country is almost level, and 

 is consequently inundated during the rainy season for hundreds 

 of miles by the rivers flowing through it The most notable excep- 

 tion to this general state of things occurs at Obidos, where the 

 whole volume of water is compressed into one channel a little 

 over a mile wide, and said to be about forty fathoms in average 

 depth A sounding taken opposite Obidos, about a third of the 

 distance across the river, showed a depth of fifty-eight fathoms, 

 measured by a steel wire and Lord Kelvin's sounding- 

 ni.achine. .\s the current of the river averages three knots in 

 the main channel, it is not easy to take .soundings by an ordinary 

 lead line ; and even with the steel wire an extra heavy weight 

 (33 lb.) has to be employed, or the results are not trustworthy. 



Besides the wire sounding-machine a submarine .sentinel was 

 used on the preliminary voyage, wherever serious doubts existed 

 about a channel through which the cable was to be laid. This 

 apparatus consists of a small winch from which a wire leads into 

 the water and drags at a short distance l)ehind a piece of wood, 

 shaped like an angle-iron, in a nearly upright position. The 

 wire is not attached directly to the piece of wood, but to a string 

 kite-fashion, and the wood is fitted with an iron foot which, on 

 coming in contact with the bottom of the water, releases one end 

 of the kite-string, .so that the wood remains attached to the winch 

 wire with one end only. The consequence is that the strain on 

 the wire is suddenly reduced to a very small amount, and the 



NO. 1390, VOL. 54] 



piece of wood appears on the .surface of the river. It depends 

 on the quantity of wire paid out how deep the kite or the sentinel 

 floats, and its action is quite trustworthy, so that it is unneces.sary to 

 take soundings by the line or by wire while the sentinel is being 

 dragged by the ship. Usually the sentinel was set at five 

 fathoms, and when it struck a bar the ship was stopped, and a 

 series of soundings taken to ascertain the exact depth of water, 

 and the extent of the shallow place. 



A further difficulty in sounding originated from the .soft nature 

 of the soil, which for the greater part of the Amazon valley is 

 alluvial clay, and allows the lead to sink into it for several feet. 

 In the narrows there appears, however, a bank of hard clay 

 (called Tabainga) which, unfortunately, blocks nearly all the 

 branches of the narrows, and creates bars all along the course of 

 the Tajipuru, the main westerly waterway connecting to the 

 Gurupa branch of the main river. Occasionally the same hard 

 clay forms shallows in the main river, but as a rule the section of 

 all the channels resembles the capital letter U, i.e. the sides are 

 very steep and the bottom flat. In this respect, as in many 

 others, the Amazon differs entirely from the Indian rivers, which 

 build up their beds above the surrounding country, occ.a.sionally 

 breaking through their natural banks and seeking a new bed. 

 The Amazon, on the other hand, carries with it only the light 

 clay sediment which forms the soil of the whole valley ; and the 

 inducement for the main stream to alter its course is therefore 

 very small, and long straight reaches are the result. 



Under these circumstances the largest vessels can ascend 

 the river nearly to the foot of the Andes, but the con- 

 stantly-changing sandbanks at the mouth of the Amazon 

 proper make this approach of the river dangerous, and the 

 State of Para is, for obvious reasons, not over-anxious to 

 have the deep channels properly buoyed and surveyed. This 

 forces all the shipping to enter the Para River, and to pass 

 the narrows if the Amazon is the goal of the journey. In doing 

 the latter, the choice for large ships lies between one of the 

 channels (called Furos) with a bar, where it joins the Tajipuru, 

 and a furo (the Macajubim) which has plenty of water, but 

 which winds about in such a serpentine fashion that only ships 

 with twin screws can pass it unassisted. 



These difficulties are, however, much diminished during the 

 rainy season, when the river rises to such an extent as to drive 

 all the inhabitants of its banks into the towns, which have been 

 built wherever a natural eminence secured the inhabitants against 

 the flood. Near the mouth the difference is naturally not so 

 great as higher up, where the influence of the tide is felt less ; 

 but at Manaos the difference in level between low river and high 

 river exceeds forty feet. 



With all rivers carrying sediment the Amazon shares the 

 peculiarity that its immediate banks are higher than the country 

 lying behind them, and thus we have in the rainy season the 

 spectacle of the main river flowing between two banks covered 

 with dense forest, and immense lakes stretching out on either 

 side of these banks. These do not entirely dry up during the 

 remainder of the year, so that the whole of the Amazon valley 

 really forms a huge swamp covered with a most luxuriant forest, 

 which below Manaos narrows to a broad belt close to the main 

 river with prairies, called Campos, at the back of the forest 

 stretching out to the hills, where the forest recommences. In 

 such a country no land communication of any sort can be 

 attempted, as the tropical vegetation and the annual inundations 

 of the rivers destroy everything that man places in the way of 

 the natural forces. By water, on the other hand, the intercourse 

 between all habitable parts of the country is easy and expedi- 

 tious since steamers were introduced in the year 1853. Belem, 

 the capital of the State of Para, lies on a branch of the Para 

 River, called Guajara, which unfortunately does not share the 

 characteristic shape of the Amazon and the furos, but forms a 

 rather shallow basin in front of the town. 



The first station on the main cable is Breves, the centre of the 

 rubber trade of the islands of the lower Amazon, situate in the 

 centre of "the narrows." 



In Gurupa, the second station of the main line, the inhabitants 

 expressed their joy at being put in communication with the rest 

 of the world by actively helping in the landing of the first shore 

 end. 



During an enforced sojourn near the mouth of the Boinasu, 

 in the midst of the most wonderful combination of islands and 

 rivers, the two naturalists, which the British Museum authorities 

 had kindly sent with the expedition, took full advantage of the 

 opportunity to explore the locality in all directions. 



