RIVER

(Lat. rivus.) In Physical Geography, an inland current of water, formed within a certain portion of the earth's surface by the confluence of brooks, small streams, or mountain torrents, and discharging itself into the ocean, a lake, marsh, or other river. 'There are few subjects in physical geography which present so wide a field for speculation as rivers, whether we regard them in an historical, political, economical, or scientific point of view. They are a ociated with the earliest efforts of mankind to emerge from a state of barbarism; but they are no le serviceable to nations which have reached the acme of civilization. In the earliest ages they were regarded with veneration, and became the objects of a grateful adoration surpa ed only by that paid to the sun and the host of heaven. Nor is this surprising; for in countries where the labours of the husbaftdman and shepherd depended for a succe ful i ue on the falling of periodical rains, or the melting of the collected snows in a far-distant country, such rivers as the Nile, the Ganges, and the Indus were the visible agents of nature in bestowing on the inhabitants of their banks all the ble ings of a rich and spontaneous fertility; and hence their waters were held sacred, and they received, and to this day retain, the adoration of tlie countries through which they flow. But it is by countries which have already made progre in civilization (to which, indeed, they largely contribute) that the advantages of rivers are best appreciated, in their adaptation to the purposes of navigation, and in their application to the useful arts. Like the veins and arteries of the human body which convey life and strength to its remotest extremities, rivers vivify, maintain, and excite the efforts of human industry; whether we regard them near their source as the humble instruments of turning a mill, in their progre as facilitating tlie transport of agricultural or manufacturing produce from one district to another, or as enriching the countries at their mouths with the varied products of distant lands. This has been so adfnirably expre ed by Pliny, tliat we cannot refrain from embodying his words in our pages. " The beginnings of a river," he says, " are insigniflcant, and its infancy is frivolous: it plays among the flowers of a meadow; it waters a garden, or turns a little mill. Gathering strength, in its youth it becomes wild and impetuous. Impatient of the restraints which it still meets with in the hollows among the mountains, it is restle and fretful; quick in its turning, and unsteady in its course. Now it is a roaring cataract, tearing up and overturning whatever opposes its progre , and it shoots headlong down from a rock; then it becomes a sullen and gloomy pool, buried in the bottom of a glen. Recovering breath by repose, it again dashes along, till, tired of uproar and mischief, it quits all that it has swept along, and leaves the opening of the valley strewed with the rejected waste. Now quitting its retirement, it comes abroad into the world, journeying with more prudence and discretion through cultivated fields, yielding to circumstances, and winding round what would trouble it to overwhelm or remove. It pa es through the populous cities, and all the busy haunts of man, tendering its services on every side, and becomes the support and ornament of the country. Increased by numerous alliances, and advanced in its course, it becomes grave and stately in its motions, loves peace and quiet, 1057 RIVERS. and in majestic silence rolls on its mighty waters till it is laid to rest in the vast aby ." Most large rivers have their origin in very elevated mountains, or on high table lands, the height and direction of which chiefly determine their size and course. For full information on the various points involved in this subject, we beg to refer the reader to the article " Rivers" in the Ency. Brit.; and we shall in this place confine our remarks to some of their most striking peculiarities,— periodical inundations, occtUlations, and reappearntice. The periodical inundations of rivers depend on great falls of rain in mountainous regions, or on the melting of snows in the neighbourhood of their source. The period depends on the return of these seasons in different places. Within the tropics, the rainy season occurs usually about the time when the sun pa es the meridian towards the tropics; and continues until his return to the same place. The rise of the Orinoco commences in May, its inundation begins in June, and the waters return to their channel in September; from which time they decrease until April of the succeeding year. In the Lower Mi i ippi, whose inundations begin in March, and are at their height in June, are found those enormous rafts of driftwood (formed during the inundations), which sometimes extend for ten or twelve miles in one ma , rise and fall with the stream, yet have a luxurious vegetation on their summits. The great rivers of Asia — the Ganges, the Indus, the Tigris, and Euphrates —have also their periods of inundation, depending on the circumstances determining the setting in of the rains on the mountains in which they originate. In the Ganges the waters begin to increase in April, and at the end of July the country, for an liundred miles along its banks, presents the appearance of a vast lake interspersed with msulated villages and woods. But of all inundations, those of the Nile are the most celebrated; nor is it po ible to find any where among terrestrial objects a more striking instance of the stability of the laws of nature, than the periodical rise and fall of this mighty river. We know by the testimony of antiquity that the inundations of the Nile have been the same, with respect to their season and duration, for three you sand years. Indeed, their certainty regulates the public revenue; for when by means of nilometers it is ascertained that the waters promise an unusually prosperous season, the taxes are proportionally increased. Shortly after the commencement of the rains of Aby in i a, in June, the river begins to rise, and attains its greatest height in August. At Cairo the greatest rise is twenty-eight feet; but in the valley of the Nile, with a mean breadth of three or four leagues, it is only four feet. It decreases gradually until the following May; and as soon as the waters are within their usual channel, the soil, moistened and enriched by the sediment deposited from the inundation, is diligently cultivated by the natives. Pliny thus speaks of the inundation:— "Justum inc remen tum est cubitorum 16, minores aquae non omnia rigant: ampliores detinent tardius recedendo. Heec serendi tempera absumunt: illae non dant sitiente. Utrumque reputat provincise. In duodecim cubit is famem sentiant, in tredecim etiamnura esurit; quatuordecim cubit a hilaritatem afferant, quindecim securitatem, sexdecim delicias." (Hist. Nat. lib. v. 9.) The engulphmcnl and reappearance oi some rivers have attracted attention in every age; nor has any satisfactory explanation been yet a igned for this extraordinary phenomenon. In the Memoir of the Abb^ Guettard, the phenomenon in question is accounted for by the spongy nature of the soil through which such rivers flow; thus the Guadiana, one of the largest rivers in Spain, suddenly disappears in the marshes near the village of Castillo de Cerrera, and after pursuing a subterraneous course for twelve or fourteen miles bursts again into day. Limestone districts afford many specimens of this phenomenon; one of the most striking of which is the occultation of the Rhone near the gorge called the Parte. There are also some curious instances in Derby shire and Yorkshire. But no country surpa es Greece in the number of its subterranean streams, the peculiarities of which are often clothed in splendid mythological fictions by her ancient bards. The waters of many valleys in the Peloponnesus have no other outlets than Cs?^^?*, or chasms, which engulph them; such are the outlets of the valleys of Tegea, Mantinea, Asasa, Stymphalus, Peneus, . A familiarity with such phenomena, and a poetical temperament, readily led the ancient Greeks to conceive still more distant secret communications; and the imagination which peopled every grove, and animated every stream with presiding deities, could easily reconcile itself to the story of the river god Alpheus, who was said to pursue his favourite nymph Arethusa beneath the bed of the ocean from Greece to the shores of Sicily.. {Traill's Physical Geography.) We subjoin, from Dr. Traill's valuable Treatise on Physical Geography, a table showing the length of the course of twenty-two of the principal rivers of tije 3 Y  [s. 1070]