Page:Collier's New Encyclopedia v. 08.djvu/87

RIVAS 61 RIVER contention are those which involve the adoration of Christ as present on the altar under the forms of bread and wine. Other points are: The E. position of the priest at consecration; lights on the holy table; the use of various vestments; the use of incense; mixing water with wine for communion; fasting before commu- nion from previous midnight; regular confession to a priest, with absolution and penance, etc. The legal position of the Ritualists is that the first Book of Common Prayer, issued in the second year of Edward VI. (1549, with altera- tions made in 1552, 1604, and 1662), is still the guide of the Church in all mat- ters pertaining to ritual, the present prayer-book not being in itself complete, but referring to this first prayer-book in its opening rubric. Various judgments have been given in ecclesiastical courts against extreme Ritualists, and some of their proceedings have been pronounced illegal. Ritualistic practices have been generally condemned by the bishops, and an act of Parliament giving them power to restrain innovations of this kind came into force on Aug. 7, 1874. The ritual- istic movement in the Church of England arose out of the High Church movement inaugurated by the Tractarians. RIVAS, capital of the department of Rivas, Nicaragua, 49 miles S. E. of Managua. The town is picturesque and is a development of the older Indian town of Nicarao, which was of impor- tance as a stronghold and center of traf- fic. The surrounding region is agricul- tural, the chief produce being cacao, the production of which gives employment to many. Pop. about 15,000. RIVER. Water falling on the land in the form of rain, or resulting from melting snow, or rising to the surface in springs, flows over the surface to a lower level. Where two slopes of land dip together the surface drainage col- lects to form a stream, and when evap- oration is not very rapid several such streams ultimately unite and the volume of water they carry flows to the sea or to a salt lake. Small streams are termed runnels, rivulets, rills, brooks, becks, or burns; large streams are termed rivers, but the word has no precise reference to the magnitude of the stream to which it is applied. The beginning of a stream — whether brook or river — is called its source, and may be a spring issuing from under- ground, a lake or marsh in which rain- fall accumulates, melting snow, or sim- ply the gathering tricklings from falling rain. The path of a stream is its course, and is the line of lowest level from the E— < source to the end, which if occurring in a lake or the sea is termed its mouth. The connected streams which unite in one river form a river system. The series of convergent slopes down which a river system flows — the land which it drains — forming its basin or catchment area, and the name watershed is also sometimes erroneously applied to it. The names watershed, waterparting, and di- vide are used to designate the boundary line separating adjacent basins. A wa- tershed is always the meeting-place of the highest part of divergent slopes, and from the characteristic form of conti- nents the main watershed of a continent is almost always the crest of a range of mountains. In many cases, however, the diverging slopes meet in a low plain the summit of which may be occupied by a great marsh whence rivers creep away in opposite directions. The basins of all the rivers draining into the same ocean are called collectively the drainage area of that ocean. The main river to which the others are said to be tributary gives its name to the whole river system. It is often difficult to decide which of sev- eral converging streams is entitled to carry the name of the main river to its source. Some geographers give this dis- tinction to the longest, others to that with the highest source, and others to that with the most direct course. The course of a typical river has been di- vided into three parts, though these are not represented in all cases. The tor- rential or mountain track is the steepest, its gradient usually exceeding 50 feet in a mile, and the velocity of its current being very great. The valley or middle track has a gradient which is rarely greater than 10 feet and often less than 2 feet in a mile. The plain track near- est the mouth of a river has a gradient of only a few inches in a mile. Rivers such as the Amazon, Mississippi, Gan- ges, Volga, and the long rivers of Si- beria, in which the plain track is of very great length, are the most valuable for navigation, the limit of easy navigabil- ity being a gradient of about 1 foot in a mile. The velocity of a river is proportional to the slope of the bed, but it also bears a relation to the depth of the channel and the volume of water flowing in it. On account of friction on the bottom and sides of the channel retarding the stream, the water flows fastest on the surface and in the middle. The carry- ing power of a river for suspended solid particles and for stones and gravel pushed along the bed depends on the velocity alone. The following table shows how rapidly the carrying power falls off as the velocity diminishes. Cyc Vol 8