SPRINGS.

The origin of springs, from which rivers have their source, though involved in much obscurity, may be said, generally, to proceed from the condensation of atmospherical vapours, the ascent of subterraneous exhalations, the filtering of water from the sea, and the melting of ice and snow. Atmospherical vapours are raised from the sea and from the earth by the heat of the sun; and, being condensed, by changes in the temperature of the air, descend again upon the earth in dew and rain. The coldness of elevated regions is well known, and whenever a current of wind carries the air of the sea, or of the plains, loaded with moisture, against mountains and mountain-chains, the invisible vapour in it becomes precipitated by the cold, either in the shape of snow or rain; owing to which beautiful arrangement of Providence, the sources of Rivers are always found in high grounds, from whence they flow, by a gradual descent, towards the sea; and the continents of the world are formed much higher in the interior than towards the coast: otherwise the falling rain would have produced unwholesome, uninhabitable marshes, in those countries which are now the delightful abodes of man, and supply the means of his subsistence. The source of the Rhine, for instance, is about 6000 feet above the level of the German Ocean, into which it falls after a course of 840 miles. The sources of the Danube are in the same mountains, and may be traced up to about the same level; and this river flows 1833 miles eastward to the Black Sea. The Rhone flows southward from the same chain 510 miles; and the various branches of the Po descend from the other declivity of this mountainous region, and, after a course of 430 miles, reach the Adriatic Sea, or Gulf of Venice, at no great distance from that celebrated city.

Springs are merely the outbreaking of water that has fallen upon the earth and sunk through the surface, where it was absorbed; so that when the earth is fully charged with water, they are most abundant; and after a season of drought they become exhausted, and in elevated parts of the country they entirely cease to flow, and the wells become dry, as has been very generally the case in this country during the latter part of the present summer. The difference in the fall of rain in elevated and in low regions, is remarkably shown even in this country; for by experiments, continued for a period of years, it has been found that in Westmoreland, which is mountainous, the average of rain is sixty-three inches perpendicular depth per annum; while in Middlesex and Hertfordshire, which are nearly level, the fall does not much exceed twenty inches. The periodical overflow of the Nile, which covers the land of Egypt, is well known; but all this water comes from a range of mountains in the centre of Africa, 3000 miles distant from the Delta of Egypt.

Rivers are very much supplied by the melting of snows in summer, which have fallen on mountainous ranges during the preceding winter; and when the changes of temperature in the spring of the year are very considerable, the effects upon rivers flowing out of these regions, are sometimes quite surprising: for instance, in the present year, the River Ohio, a considerable branch of the Mississippi, rose seventy-eight feet in perpendicular height above its ordinary level, and in the flat country adjoining the Mississippi caused an overflow of the water 150 miles wide.

Besides these collections of water from external causes, springs and fountains have an extensive origin in an internal formation, caused by the combination of oxygen and hydrogen gases, which, whenever they meet, decompose each other, and produce water.

Springs are of several kinds, according to the preponderating cause of their origins; as perennial, temporary, intermitting, or reciprocating. The first, or perennial springs, seem to be supplied by the gases just mentioned; they flow continually, with little or no variation in the quantity of water they emit. Temporary springs flow only during certain seasons of the year, and are probably supplied by rain and melted snow. Intermitting springs flow and stop alternately, in consequence, it is presumed, of their connexion with the sea. Reciprocating springs flow constantly, but in a variable manner as to quantity; of which the cause has not been well explained.

In the formation of lakes, we see another instance of the consideration of Providence, for they operate, in most cases, like immense cisterns for receiving these sudden accumu lations of waters; so that the rivers forming their outlet are not increased, by sudden falls of rain or melting of snow, in any thing like the degree they otherwise would be, because the quantity of water which is sufficient to raise suddenly the surface of a lake one foot, would, perhaps, raise the river fifty feet, if it were not so spread out over a large space. The winding of rivers, which adds so much to their beauty and to their fertilizing effects, has also another most important effect, which is evidently the work of the Parent of Good, that is to say, it retards the flow, and preserves the water in them three or four times as long as it would otherwise remain in the channel; but for this, the formation of lakes, and the deposit of water in the earth itself, the upper part of the course of rivers would be entirely dry after a few weeks' cessation of rain, and the elevated regions of the earth would be infinitely less habitable then they are

at present.

COURSES OF RIVERS.

Rivers usually rise in elevated regions; and the origin of the largest may generally be traced to a small rill, oozing from a bed of sand, or clay, and descending from nearly the summit of some mountainous chain. This insignificant stream receives in its course the tributary waters of numerous brooks and rivulets; so that by the time it reaches the plain, it becomes a tolerably broad river. In its progress to the place where it discharges its waters, either into the ocean, or into some river more considerable than itself, it is increased by many smaller streams: thus, the Volga receives the waters of more than two hundred rivers and brooks, before it falls into the Caspian; and the Danube is enriched with an equal number, in its way to the Black Sea.

It sometimes happens that two or more rivers have their springs upon, or near, the summit of the same mountain or chain, but flow down in different directions; which has led to an erroneous notion that they have but one common

source.

The course, or run, of rivers, is of variable length; ex tending from a few to some hundreds, or even thousands, of miles. It is determined by the several circumstances of distance from the source to the sea, or other mouth; the nature and arrangement of the country which it traverses; the number and magnitude of its tributary streams; and the peculiarities of the climate, in respect of temperature, seasons, &c. Generally, the extent is in pro portion to the height of its source; and it always bears a relation to the surface of the valley, of which it receives the auxiliary waters.

The beds, or channels, of rivers, are partly owing to those revolutions, as earthquakes and volcanic eruptions, which, at different times, have altered the face of the earth, and partly to the natural action of the rivers themselves. To the former may be ascribed the remarkable examples of rocks and large beds of compact strata penetrated by rivers, of which the velocity and weight are far from being considerable. The latter may be naturally expected in loose and soft soil, which readily gives way to a gentle pressure of long continuance, assisted by the soaking of the parts acted upon. Great alterations are made in the sides and bottoms of the beds in the course of time; some parts being depressed, or worn down, by the force of the current, while others are raised by the gradual deposition of mud and other products of the soil brought down from a distance. Hence it happens, that the entire course of a river is sometimes changed, more especially towards its mouth. As rivers proceed from their sources to their terminations, their channels are usually increased in breadth, excep when they flow through narrow passes between rocks or

mountains, which give the current an increase of velocity proportioned to the compression they occasion at its sides. When obstacles of this nature stretch across a valley, so as to leave no immediate outlet for the waters, a lake is formed, into which the stream continues to flow, till, rising above the interposing dam, it rushes down the opposite side in a cataract, and resumes its progress through the lower parts of the succeeding valley.

The rapidity with which a river flows depends upon the quantity of its waters, the breadth of its channel, and the declivity of its bed: for, as the breadth of the channel is greatest in a plain country, the current will be there slower than in a sloping mountainous district. The mouths of rivers are various in their appearances. In some cases, the water glides smoothly into the sea, mixing almost immediately with its waves; in others, the force of the river and the volume of its waters are so considerable, as to preserve a well-marked distinction between the fresh water and the salt, to a great distance from the place where they meet. Such is the case with the rivers Maranon and La Plata; the former of which sends an immense body of water into the ocean with such force, that it remains unmixed with the briny wave to the distance of eighty leagues. When the current of a river aimost stagnates in a level country, its course is disturbed by every trifling obstacle, and a variety of outlets is the consequence. This diminished velocity also allows the waters to deposit the earthy particles which the current had brought down from the higher and more rapid parts of its course; and alluvial tracts are formed at the outlet, as in the cases of the Rhine, the Volga, the Ganges, the Nile, the Niger, the Oronoco, and many other large rivers. Sometimes, these sluggish streams deposit banks of sand, of greater or less extent, through which the water seems scarcely to find a passage into the ocean. Lastly, there are some rivers, whose currents are, for a time, so retarded by the tides of the sea, that their waters are thrown back, so

that they overflow their banks, and inundate the surrounding plains to a great extent.

The greatest velocity of a river is usually about the middle of its breadth and depth, and the least towards the bottom and sides.

PECULIARITIES OF RIVERS.

Several of the rivers in the following list consist of two or more streams, bearing various names in the countries through which they respectively flow. But the measurement, commencing at the fountain-head and continuing to the entrance of the river into the sea, is to be understood as comprising the whole, under whatever denomination the parts may be geographically known. Some rivers, which preserve their name from beginning to end, are in themselves inconsiderable; but receiving in their progress the waters of larger rivers, they become magnificent streams, and, by retaining their own title, cast a shade over others to which they are indebted for their importance. In some cases, as of the Nile, two streams contribute by have two sources; and it seems difficult to decide which of their union to form one large river, which thus appears to the two is the main channel.

COMPARATIVE SIZE OF RIVERS.

In comparing the sizes of different rivers, and the masses of water they contain, we must take into account the length of their course, their breadth, and depth; together with their velocity at various parts. This is obviously a difficult, and, it may be added, almost an unattempted task. It is easy enough, on the whole, to compare many of them together, as to their length, or breadth, or depth, &c., separately; but all these require to be combined, in order to exhibit their true relative magnitudes and proportions. Major Rennell, in his Memoir on Hindoostan, has given a list of the relative lengths of rivers, the Thames being taken as unity, from which the following scale is constructed ::

According to this scale, the Rhône is three-fourths longer than the Thames; the Seine twice and a half as long; the Tagus three times; and so of the rest. The length of the Thames is assumed to be about forty-five leagues, or nearly one hundred and fifty-six miles; the multiplication of which by the number standing against any given river, will show its length in English miles. But the Major's computations do not exactly accord with the existing amount of information on the subject. Hence the Plate at the head of this article will be found to differ materially from him. Till lately, the Maranon, or River of Amazons, was supposed to be the longest river in the world; but it is now ascertained that the Mississippi (an Indian name, signifying Father of Waters) and Enesei exceed it. Major Rennell also estimates the extent of the Thames too low; its length being, according to the latest admeasurements, two hundred and fifteen miles.

With this explanation, the reader will be able to appreciate the motives by which we have been guided in the construction of our CHART OF THE PRINCIPAL RIVERS IN THE FOUR QUARTERS OF THE WORLD. It is formed from

the best recent authorities, and is at least an approach to the truth; subject, nevertheless, to correction from future observations and discoveries.

The Chart exhibits the rivers as drawn out in straight lines, or nearly so, for the purpose of comparison; and some remarkable places, as cities or towns, on their banks, and lakes through which they run, are inserted at their respective distances from the mouth of the river to which they belong. In the following Table, which may be considered as an Appendix to the Chart, the rivers are set down in their relative proportions, the Thames being taken as unity; that is, being reckoned as the number one. This will be found convenient for the memory, which more readily receives and retains a comparative measurement, than a series of abstract numbers. In addition to this general method, the measurements are given in English miles; together with the countries through which the rivers flow, the sites of their origins, principal towns, &c., by which they pass, and the ocean, &c., into which they discharge their waters. The names in italics have been omitted on the Chart, for the sake of clearness.

Tay.

.......

Dundee.

Trent

......

185

Humber.

Staines, North Sea, at 215

Sheppy Isle.

mosa.

Halifaia, Goos, Mograt, Merawe, Don- Mediterranean, gola, Essouan, Edfou, Esneh,Ghennah, betw. Alexandria Es-Siout, Minich, Benisouef, Cairo and Damietta.

York.

more.

3240

600

between Elton and Bellair.

... Columbia

15 Maranon, or Amazon Brazil

171

1600

site Whale Isle.

Atlantic, between 2400 Capes St. Antonio and Maria.

Atlantic, opposite 3350

Isle Caviana,

Natchez, New Orléans.

THE SHANNON.

The Shannon, in Ireland, originates in a small lake, a few miles south of Sligo; and, soon afterwards, falls into Lough Allen. Here it seems to be lost; but it comes out from the southern extremity, with an increase of water, and passes successively, with similar advantages, through Loughs Esk and Ree, into which, also, several considerable rivers and brooks empty themselves. The Shannon, thus increased, now becomes a noble river, and after flowing through Lough Derg, where it receives fresh accessions, it passes Limerick, and expands into a grand æstuary, or arm of the sea, opening into the Atlantic Ocean. The Shannon is, therefore, a collective stream, rather than an original river.

THE THAMES.

The same may be said of our Thames, which rises on the south-eastern side of the Cotswold hills, in Gloucestershire, in which spring the four rivulets of the Lech, the Coln, the Chiron, and the Isis; each of which is so small, that a man may check its progress with his foot. The first three fall into the Isis, by which name the river is known till it has passed Abingdon, in Berkshire. By this time, from the junction of several streams, some of them larger than itself, it becomes a broad river. At Dorchester, about seven miles below Abingdon, it is joined by the Thame, a moderately broad stream formed by the union of many rivulets in the centre of Buckinghamshire. This junction, though with a stream of less size, is fatal to the Isis, so far as its name is concerned; for, during the remainder of its progress, it is known by the appellation of Thames, formed, as is believed, by a combination of the two titles Thame-Isis. From this point, it proceeds by a very circuitous course to London, and thence, in a general easterly direction, to the North Sea, of which it forms a grand æstuary between the Kentish and Essex coasts.

OF EUROPE.

easterly course through Montgomeryshire, receiving in its way several rivulets, and reaches Shrewsbury, in Shropshire: it then makes a bold sweep through the counties of Worcester and Gloucester, and, suddenly widening below Bristol, opens into the Bristol Channel. This river has more of an original character than many others; for, though enriched by other streams, it retains its name from the fountain-head till it enters the ocean, and is uninterrupted by lakes. It is remarkable for the impetuosity of its tide, which sometimes rushes in, with a head of water, called a bore, at a height of three or four feet, accompanied with an astounding noise. This is occasioned by the sudden contraction which the river gives, at its mouth, to the waters of the Atlantic, as they flow in.

THE SEINE.

The Seine, one of the most picturesque rivers in France, is more indebted for magnitude to its tributary streams, than to the resources of its spring. All the rivers are considerable, and have their auxiliaries, the waters of which fall into one common channel, called the Seine, from one of the lesser rivulets which contribute to the supply.

THE GARONNE.

The Garonne, another river of France, issuing from the Pyrenées, is a small stream, till joined by the Arriège, the Tarn, the Aveiron, and the Lot; after which it becomes a large river. Below Bordeaux, it is further increased by the Dordogne: it then obtains the name of Gironde, and opens into a large æstuary of the Bay of Biscay.

THE RHÔNE.

The Rhône affords an instance of an auxiliary superseding its principal, and giving name to a river, to which, naturally, it is tributary. From a vast mass of ice, in an Alp, rising ten thousand feet above the level of the sea, between the canton of Uri and the Valais, gushes the Rhône; and as it rolls about 90 or 100 miles across Switzerland, its waters are augmented by an almost infinite number of torrents and streams, from the adjacent mountains. At length, it pours its vast volume of water into the lake of Geneva; and re-issuing from the opposite extremity,

enters France. There it joins the Saône, and, according | to the direction of the two streams, the one flowing in nearly a straight direction, from north to south, and the other joining it from the east, it ought to lose its name; but, being the most powerful, it retains its original appellation till it enters the Mediterranean, by several mouths, a few miles west of Marseilles. THE RHINE.

The Rhine affords an instance of a large river losing its name before it reaches the ocean. It arises amidst deserts of ice and snow, near the summit of the Alps, in the Grisons' country, and being quickly joined by two other streams, called the Middle and Upper Rhine, which descend from the same mountainous regions, from heights exceeding 6000 feet, the united waters work their way through the solitary valley of Rhinewald, sometimes flowing secretly beneath arches of perpetual ice, at others, descending with impetuosity over rocks of granite, and appearing to gain new strength from every opposing obstacle. After quitting the Rhinewald, and receiving various torrents, the Rhine passes through the Lake of Constance, and forms the

northern boundary of Switzerland, as far as Basle. It then assumes a northerly course, forms a boundary between France and Baden, and reaches Mentz and Cologne, whence it pro ceeds to Cleves, and enters the Netherlands, where it divides into several branches, each of which receives a particular denomination, and enters the North Sea at a different place; but the name of the Rhine is lost.

THE VOLGA.

THE ENESEI.

The Enesei, or Yenesei, consists of a series of streams, one of the least important of which gives name to the whole. The Enesei, properly so called, rises among the Altai Mountains, in the high lands of Mongolia, and penetrating between the hills, takes a northerly course through the governments of Kholyvan and Tobolsk, to the Arctic Ocean. During its course, which deviates but little from a straight line, it receives several rivers, more considerable than itself, besides some rivulets; so that from being a mere brook, it becomes, at Eneseisk, a broad river. For this accession, it is mainly indebted to the Angara, which flows into it a few miles above Eneseisk, and is, indeed, the stream by which the length of the river is measured, agreeably to the opinion of many oriental writers, who, observing its superior extent and magnitude, say the Angara receives the Enesei, and afterwards flows into the Arctic Sea. This river, the Angara, rises on the south side of the Altai Mountains, or rather on the broad summits of that range, and, flowing in a westerly direction till it finds a declivity, enters the province of Irkoutsk, where it falls into the Lake Baikal, on the south-east side. During this course, it receives the waters of two streams which issue from small lakes on the south-west. From the north-west side of the Baikal Lake, but about fifty miles south of the confluence of the river just described, flows out the Angara, which is considered a continuation of the same stream; this takes a zig-zag direction, receiving in its progress the waters of the adjoining high lands, and at length falls into the Enesei, above Eneseisk, where it loses its name. In the measurement of the Enesei, therefore, it must be remembered, that the length of the Angara is included, and that from the place of its junction, the original river is neglected.

THE OBI.

The Obi presents a nearly similar instance of irregularity in the estimate of length, but in a contrary order. A small stream, called the Dschabekan, formed by the junction of the Sira and some other rivulets, which issue from the Great Altai range, in Mongolia, passes, first by an underground channel, and afterwards through an opening of the Lesser Altai Mountains, into the Altyn or Teletskoe Lake, from which, on the northern extremity, issues another river, called the Byia. These are considered as one and the same river, under different names. As it proceeds, it receives several other streams, and obtains the name of Obi, between Barnaul and Kholyvan. It then flows in a serpentine direction towards the north and north-west, continually increased by other rivers, till it meets the Irtisch, which rivals it in magnitude; but the Obi still preserves its name; though it is evident that the stream, from this point, is a continuation of the Irtisch. After this junction, the river, which is now several miles in breadth, flows northward, with a curve towards the west, and forms the Sea of Obi, in the Arctic Ocean. Its whole length is estimated at 2180 miles, the greater part of which is navigable. But this is not the river measured by geographers in their comparative scales of rivers: from its junction with the Irtisch, they abandon the Obi, and proceed with the former stream, which, at the point of union, is in a more direct line, though, above Tobolsk, it flows in nearly the same direction as the Obi, at the distance of a few degrees

to the westward. Like the Obi, it rises in the Great Altaian chain; it passes through the Lake Zaizan, and enters Siberia Numerous about two hundred miles from its source. tributary streams afterwards swell its waters; among which are the large rivers Issim and Tobol: so that when it joins the Obi, at Samarova, it fully equals it in magnitude; and, from its direction, seems naturally entitled to retain its name to its confluence with the ocean.

THE YANG-TSE-KIANG, or SON OF THE SEA. Of the Chinese rivers, the Yang-tse-kiang, or Son of the Sea, deserves particular notice; the grandeur of its stream having struck all travellers. It originates in the Desert of Cobi, whence it makes its way between the Kola Mountains, into Tibet, the eastern side of which it traverses, under the name of Kintcha-kiang, in a southerly direction, collecting, in its way, the waters of many streams. On entering China, it is joined by the large river Yalong-kiang, and then takes a circuitous course, nearly across the middle of the country, towards the west, receiving, as it rolls along, the tribute of many rivers, and connecting itself with, or forming, several lakes of considerable size. Its whole length is computed at 3290 miles; its average breadth is upwards of two miles; and its numerous tributary streams, in some instances, equal the Thames for magnitude. In its course through the central parts of China Proper, it waters several cities; and, after passing Nankin, forms a kind of Delta, and falls into the Yellow Sca, nearly one hundred and forty miles east of that city.

THE GANGES.

The Ganges, one of the largest, though not the longest, rivers of Asia, and the most sacred stream of the Hindoos, issues from an opening, called by the natives Gangoutri, or the Cow's Mouth, situated among the perpetual snows of the Himalay chain, from whence it descends for a considerable distance among the mountains. This is the Bhagirathi, or most sacred branch of the Ganges; but the Dauli, being much longer, should be considered the principal source. This river proceeds from the immediate base of the highest part of the chain; and from Hurdwar to Allahabad, where it receives the Jumna, its width is from a mile to a mile and a quarter. After this junction, its course becomes more winding, and its bed wider, from various rivers which flow into it: so that its channel is sometimes three miles across, and frequently divided by islands. For about five hundred miles above its junction with the sea, its depth, when least, is about thirty feet. Previously to entering the ocean, its breadth suddenly expands, and the current, from being rapid, becomes so weak that it has not power to disperse the banks of mud and sand at its mouth: hence a Delta is formed, which commences about two hundred miles in a direct line from the sea, or three hundred by the course of the stream; and the western branch constitutes the Hooghly river, on the east bank of which stands Calcutta. Between the moun tains and the sea, the Ganges receives the waters of eleven large rivers; some of which are equal to the Rhine, and none less than the Thames. Like other large rivers, in or near the torrid zone, the Ganges is subject to periodical floods, by which, in the latter end of July, all the lower parts of Bengal are overflowed for a hundred miles in width • the villages and trees only being seen above the water,