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that could be proposed. Henceforward the term Natural Religion must be confined either to the primeval stock of beliefs, however generated, which can be extracted from the earliest languages and monuments of mankind. Few, however, would uphold this period in the history of our race as a true standard of nature. Or, secondly, it must denote such stages of development as are confirmed by the history and observation of religions, irrespective of their claims to truth or of any supposed rivalry in regard to Revelation.

Mr. Max Müller has also, as we think, done good service by proving on new grounds, and from fresh data, the following facts in connexion with the early history of mankind; facts which, in view of the materialistic tendencies of the age, can - hardly be too highly estimated. He seems to us to have raised an additional argument for the unity of the human race; to have shown successfully that man was clearly in his earliest days a religious animal, conscious of his own dependence, with a sense of infinity, exhibiting in the most savage races an idea of a Divine Power, exercising a belief in an invisible yet omniscient God, the Creator, Author of good if also of physical ills ; one who punishes the wicked here and hereafter, who hears prayer, who absolves from sin : to Him sacrifice is due from the creature, worship, thanksgiving, and intercession; and He holds communion with the souls of men. Man, then, is distinguished from the brutes, his congeners, not only by his power of language, as a specific faculty, and by his capacity of generalisation, but most by his religious ideas. For these are of all the most important, not only in that they are the most characteristic and differential (for there is not the smallest ground to attribute them to any other, past or present, order of animals); but further as guaranteeing an existence hereafter correspondent to our present consciousness that we form part of a system which includes a state of probation and trial. Such conceptions-and their continuance throughout the history of our race has now been demonstrated-are altogether incompatible with theories of existence which terminate'in blank materialism ; in' a stream of tendency by which all things fulfil * the law of their being ;' in a self-contained cycle of evolution ; or in a pantheism of which we are indeed the elements, but which only, because we perish, never dies.

ART. VI.-The Paraná, the Uruguay, and the La Plata

Estuaries. By J. J. RÉVY, Memb. Inst. C. E. Vienna, &c.

London: 1874. IT I would be difficult to point out any part of the world, in

which it is of more importance that the laws which regulate the flow and escape of water should be thoroughly understood, than in Great Britain. The question comes practically home to us all. In our stormy and uncertain climate, the very aspect of our architecture betrays the fact that protection from rain and snow is one of the first objects of the builder. On the capricious character of our rainfall, the growth and the ingathering of our crops primarily depend. The course of commerce, filling with its wealth our noble and numerous harbours, is intimately dependent on the hydrographical advantages which they afford. For a large area of fen district in the Eastern Counties, man yet maintains a struggle with the sea, and with the land floods, hardly less precarious than that which has so long taxed the resolution of the sturdy Dutch. For the comfort of our homes, for the yield of our harvest, for the supply of our towns and cities with a prime necessary of life, and for the security of our commerce, we depend on the hydraulic skill of our engineers,

It may be naturally assumed by those who have not been led to make any special study of the subject, that the countrymen of Watt, of Telford, and of Stephenson have, at all events, been the pioneers of the engineering of the present century. To England is due the honour, not only of being the cradle of the steam-engine and the nurse of the railway, but also of being the originator of the steam-boat. Hydraulic operations, of a magnitude never contemplated until actually taken in hand by our miners, have long drained those deep mines, of metal and of coal, which rank among the most precious sources of our national wealth. In England, moreover, to an extent only partially attempted in the great cities of the Continent, a domestic hydraulic service has been long organised. The best form of apparatus, which supplies both cold and hot water on every floor, and furnishes a bath at a minute's notice, has become more common, in houses of a moderate size, in Liverpool than in London-a matter as to which that great Lancashire port may feel justly proud. A fourth part of the low-water supply of the River Thames (according to one estimate, which we take, however, to be underrating the river) is daily pumped out by the Metropolitan water companies; led, under gentle but adequate pressure, to every house in the district, and carried back to the natural channels of drainage, laden with all the refuse that would otherwise accumulate in our great city. Certainly it may well be thought the English are a people, amongst whom the science and the practice of hydraulics have been carried to the utmost extent.

As a practical question, indeed, it cannot be denied that our experience is very large. The very necessities of our climate have rendered this fact indisputable. If we compare the aspect of any great building-palace, or church, or hall-with that of the masterpieces of classical antiquity, we shall find that a peculiar stamp is set on our native architecture by the exigencies of the weather. A lion's mouth, or some similar simple outlet, vomits forth the rapid downfall that sweeps the flat roofs of temple or tower in Italy or Greece. But gutters, rain-water heads, and down-pipes, in complex and not always ornamental arrangement, form as distinctive features of our buildings as the chimneys themselves. It is only in very out-of-the-way districts that the water shot off from the snugly thatched roof finds its own unaided way to the ground.

We shall be safe, at all events, in assuming the position, that it is highly essential that hydraulics should be thoroughly understood in this country. The question, how far this is actually the case, is, however, altogether different. It is one to which a reply is, manifestly, important. But that reply should not be lightly hazarded. it is one as to which it is worth while to take some degree of trouble, in order to arrive at certitude. Our health, our comfort, our prosperity ; the amelioration of our climate; the yield of our agriculture; the facilities for our manufactures; the requirements of our commerce; are all so intimately dependent on a thorough knowledge of hydraulic law, as well as of hydraulic practice, on the part of our engineers and architects, that the question whether our command of the subject is really the best attainable by the human mind, is one of great interest to us all.

We have good grounds for forming the opinion that the laws of hydraulic action are far from being thus thoroughly understood, even by the professional and scientific men of England. We may be challenged, as we are of course aware, for a scientific justification of this doubt. But before entering into an inquiry that may tend to become somewhat technical in its nature, we will offer a reason why, at the first glance, it is not unlikely that our knowledge is imperfect.

In all natural science there exists a broad distinction be

tween phenomena of a delicate and exact nature, that may be made the subject of careful experiment; and phenomena on a scale of magnitude and grandeur that can be the object of observation alone. We may weigh, to the fraction of a grain, the water absorbed by a plant; we can only look on with awe at the sudden inrush of a great tidal wave. To a certain extent all our physical knowledge is experimental. However searching and comprehensive may be the action of physical force (as in the simplest and sublimest case, that of the great force of Gravity), careful experiment is a necessary preliminary to the determination of the uncontrolled applicability of that force in each instance. It is only when we obtain mathematical proof, that we are justified in ascribing the course of phenomena to the sole action of any great primary law.

Now when the laws investigated are of great magnitude, and of corresponding simplicity, much inconvenience may result from drawing inferences from experiments made on a scale that is comparatively small. It is far safer to reduce than to enlarge. From good observations, in cases where bulk, weight, and velocity are all very high (as in the movement of the planetary bodies), we may deduce rules applicable to cases of minor magnitude and movement, with much greater accuracy and safety than can be attained by the reversal of the process. It is far safer to predict the course of a small stream, or the effect of a small tide, from observations of a great river or a rapid sea, than it is to estimate the movements of the Atlantic from observations, of the Mediterranean, or to gauge the flow of the Plata according to our experience of the Thames.

It is precisely here that the matter is brought home to our notice. M. Révy, a member of the Institute of Civil Engineers of Vienna, has been consulted on hydrographic and hydraulic questions arising in the dominions of the Argentine Republic. There he found himself launched on one of the largest rivers of the world. Second only to that regina fluviorum, the Amazon, the Paraná and its affluents form the main outfall of a vast triangular area, bounded by the Andes on the west, by the southern watershed of the basin of the Amazon on the north, and by the mountain chains and ridges that flank the Atlantic coast of South America on the east. From the delta of the Amazon to that of the Plata, a range of thirtyfive degrees of latitude, the rivers that enter the Atlantic derive their waters from a succession of broken and interrupted versants (the total area of which is but small when compared to the great central district, with its numerous ramifications) the unevaporated rainfall of which tends to the estuary of the Plata. The basin' of the Amazon, with its embouchure lying on the equator itself, attracts a heavier rainfall than that which visits any other portion of the surface of our planet. But its area is inferior to that of the water-, sheds converging on the Plata. It is to the greater depth of the equatorial rainfall, that the superiority of the volume of the Amazon, as compared with that of its southern sister, must be principally attributed.

The estuary of the Rio de La Plata, if we consider it to fall into the Atlantic at Monte Video, is nearly seventy geographical miles in width. Trending from the north-west, in a distance of 150 miles, it narrows irregularly, to a width of about thirty miles. ' At this point, the broad, deep channel of the Uruguay, lying on the meridian, makes a far more imposing show, as far as the map is concerned, than do the two sess variable streams, or rather river mouths, by which, under the names of the Paraná Guayazu and the Paraná de las Palmas, the mighty central flood, stealing through its own delta for a distance of sixty miles from the division of the streams, enters the common frith.

The Uruguay, however, is rather a colossal 'torrent than a gigantic river. Its volume presents extraordinary fluctuations. It is at its lowest in December. About 200 miles above its mouth, or last contraction of width, at Higueritas, the Uruguay flows through a rocky channel, called the Corralito. The length of this natural canal is stated at about 700 feet; its width at 145; and a current of six feet deep, flowing at the rate of five miles an hour, represents the volume and flow of the river. This is rather more than two-and-a-half times the estimated summer flow of the Thames. But in the great periodical rise of the river, this fair-weather channel is completely submerged and lost to view. The great flood, which occurs in September and October, rises at the rate of three feet per diem, till it attains a height of from forty-five to fifty feet above the low-water line at Salto, a port two miles above the Corralito. The cross-section of the river, during flood, is more than five times that above estimated. But this proportion gives no idea of the increase of volume, which is due, not only to the enlargement of the water-way, but to a more than tenfold increase in the velocity of the current.

The steady and constant flow of the Paraná forms a remarkable contrast to the violent fluctuations in the supply of the Uruguay. An immense body of water is constantly thrown into the Atlantic by the former noble stream, and its low-water supply never sinks, we are told, below the half of its food.

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