Ti'gris (Τίγρις; Vuig. Tygris, Tigris) is used in the Sept. as the Greek equivalent of the Hebrew Chiddekel (חַדֶּקֶל) among the rivers of Eden (Ge 2; Ge 14), and is there described (so some render) as "running eastward to Assyria." After this we hear no more of it, if we except one doubtful allusion in Nahum (2, 6), until the Captivity, when it becomes well known to the prophet Daniel, who had to cross it in his journeys to and from Susa (Shushan). With Daniel it is "the Great River" הִנָּהָר הִגָּדוֹל — an expression commonly applied to the Euphrates; and by its side he sees some of his most important visions (Daniel 10-12). No other mention of the Tigris seems to occur except in the Apocryphal books, and there it is unconnected with any real history, as in Tobit (6, 1), Judith (1, 6), and Ecclesiasticus (24, 25). The meaning and various forms of the word have been considered under HIDDEKEL SEE HIDDEKEL (q.v.). It only remains, therefore, in the present article, to describe more particularly the course, character, and historical relations of the stream.
1. The Tigris, like the Euphrates, rises from two principal sources. The most distant, and therefore the true, source is the western one, which is in lat. 38° 10', long. 39° 20'nearly, a little to the south of the high mountain lake called Goljik, or Golenjik, in the peninsula formed by the Euphrates, where it sweeps round between Palou and Telek. The Tigris's source is near the south-western angle of the lake, and cannot be more than two or three miles from the channel of the Euphrates. The course of the Tigris is somewhat north of east, but, after pursuing this direction for about twenty- five miles, it makes a sweep round to the south and descends by Arghani Maden upon Diarbekr. Here it is already a river of considerable size, and is crossed by a bridge of ten arches a little below that city (Niebuhr, Voyage en Arabie, p. 326). It then turns suddenly to the east and flows in this direction past Osman Kieui to Til, where it once more alters its course and takes that south-easterly direction which it pursues, with certain slight variations, to its final junction with the Euphrates. At Osman Kieui it receives the second, or Eastern, Tigris which descends from Niphates (the modern Ala-Tagh) with a course almost due south, and, collecting on its way the waters of a large number of streams, unites with the Tigris half- way between Diarbekr and Til, in long. 41° nearly. The courses of the two streams to the point of junction are respectively 150 and 100 miles. A little below the junction, and before any other tributary of importance is received, the Tigris is 150 yards wide and from three to four feet deep. Near Til, a large stream flows into it from the north-east, bringing almost as much water as the main channel ordinarily holds (Layard, Nineveh and Babylon, p. 49). This branch rises near Billi, in northern Kurdistan, and runs at first to the north-east, but presently sweeps round to the north and proceeds through the districts of Shattak and Boktan with a general westerly course, crossing and re-crossing the line of the 38th parallel, nearly to Sert, whence it flows south-west and south to Til. From Til the Tigris runs southward for 20 miles through a long, narrow, and deep gorge, at the end of which it emerges upon the comparatively low, but still hilly, country of Mesopotamia, near Jezireh. Through this it flows with a course which is south-southeast to Mosul, thence nearly south to Kileh- Sherghat, and again south-southeast to Samara, where the hills end and the river enters on the great alluvium. The course is now more irregular. Between Samara and Baghdad a considerable bend is made to the east; and, after the Shat el-Hie is thrown off in lat. 32° 30', a second bend is made to the north, the regular southeasterly course being only resumed a little above the 32nd parallel, from which point the Tigris runs in a tolerably direct line to its junction with the Euphrates at Kurnah. The length of the whole stream, exclusive of, meanders, is reckoned at 1146 miles. It can be descended on rafts during the flood season from Diarbekr, which is only 150 miles from its source; and it has been navigated by steamers of small draught nearly up to Mosul. From Diarbekr to Samara the navigation is much impeded by rapids, rocks, and shallows, as well as by artificial bunds, or dams, which in ancient times were thrown across the stream, probably for purposes of irrigation. Below Samara there are no obstructions; the river is deep, with a bottom of soft mud, the stream moderate, and the course very meandering. The average width of the Tigris in this part of its course is 200 yards, while its depth is very considerable.
Besides the three head-streams of the Tigris which have already been described, the river receives, along its middle and lower course, no fewer than five important tributaries. These are, the river of Zakko, or Eastern Ktabfir, the Great Zab (Zab Ala), the Lesser Zab (Zab Asfal), the Adhem, and the Diyaleh, or ancient Gyndes. All these rivers flow from the high range of Zagros, which shuts in the Mesopotamian valley on the east, and is able to sustain so large a number-of great streams from its inexhaustible springs and abundant snows. From the west the Tigris obtains no tributary of the slightest importance, for the Tharthar, which is said to have once reached it, now ends in a salt lake a little below Tekrit. Its volume, however, is continually increasing as it descends in consequence of the great bulk of water brought into it from the east, particularly by the Great Zab and the Diyaleh; and in its lower course it is said to be a larger stream and to carry a greater body than the Euphrates (Chesney, Euphrates Expedition, 1, 62).
2. The Tigris, like the Euphrates, has a flood season. Early in the month of March, in consequence of the melting of the snows on the southern flank of Niphates, the river rises rapidly,. Its breadth gradually increases at Diarbekr from 100 or 120 to 250 yards. The stream is swift and turbid. The rise continues through March and April, reaching its full height generally in the first or second week of May. At this time the country about Baghdad is often extensively flooded, not, however, so much from the Tigris as from the overflow of the Euphrates, which is here poured into the eastern stream through a canal. Farther down the river, in the territory of the Beni-Lam Arabs, between the 32nd and 3ist parallels, there is a great annual inundation on both banks. About the middle of May the Tigris begins to fall, and by midsummer it has reached its natural level. In October and November there is another rise and fall in consequence of the autumnal rains; but, compared with the spring flood, that of autumn is insignificant.
The water of the Tigris, in its lower course, is yellowish, and is regarded as unwholesome. The stream abounds with fish of many kinds, which are often of a large size (see Tobit 6:11, and comp. Strabo, 11:14, 8). Abundant water-fowl 'float on the waters. The banks are fringed with palm-trees and pomegranates, or clothed with jungle and reeds, the haunt of the wild boar and the lion.
3. The Tigris, in its upper course, anciently ran through Armenia and Assyria. Lower down, from about the point where it enters on the alluvial plain, it separated Babylonia from Susiana. In the wars between the Romans and the Parthians we find it constituting for a short time (from A.D. 114 to 117) the boundary line between these two empires. Otherwise it has scarcely been of any political importance. The great chain of Zagros is the main natural boundary between Western and Central Asia; and beyond this the next defensible line is the Euphrates. Historically it is found that either the central power pushes itself westward to that river, or the power ruling the west advances eastward to the mountain barrier.
The Tigris is at present better fitted for purposes of traffic than the Euphrates (Layard, Nineveh and Babylon, p. 475), but in ancient times it does not seem to have been much used as a line of trade. The Assyrians probably floated down it the timber, which they were in the habit of cutting in Amanus and Lebanon to be used for building purposes in their capital; but the general line of communication between the Mediterranean and the Persian Gulf was by the Euphrates. According to the historians of Alexander (Arrian, Exp. Alex. 7:7; comp. Strabo, 15:3, 4), the Persians purposely obstructed the navigation of the Lower Tigris by a series of dams which they threw across from bank to bank between the embouchure and the city of Opis, and such trade as there was along its course proceeded by land (Strabo, ibid.). It is probable that the dams were in reality made for another purpose, namely, to raise the level of the waters for the sake of irrigation; but they would undoubtedly have also the effect ascribed to them, unless in the spring flood-time, when they might have been shot by boats descending the river. Thus there may always have been a certain amount of traffic down the stream; but up it trade would scarcely have been practicable at any time farther than Samara or Tekrit, on account of the natural obstructions and of the great force of the stream. The lower part of the course was opened by Alexander (Arrian, 7:7); and Opis, near the mouth of the Diyaleh, became thenceforth known as a mart (ἐμπόριον), from which the neighboring districts drew the merchandise of India and Arabia (Strabo, 16:1, 9). Seleucia, too, which grew up soon after Alexander, derived, no doubt, a portion of its prosperity from the facilities for trade offered by this great stream.
4. The most important notices of the Tigris to be found in the classical writers are the following: Strabo, 11:14, 8, and 16:1, 9-13; Arrian, Exped. Alex. 7:7; Pliny, Hist. Nat. 6:27. See also Smith, Dict. of Gr. and Romans Geog. s.v. Among modern writers may be mentioned Layard, Nineveh and Babylon, p. 49-51,464476; Loftus, Chaldaea and Susiana, p. 3-8; Jones, in, Transactions of the Geog. Soc. of Bombay, vol. 9; Lynch, in Journ. of Geog. Soc. vol. 9; Rawlinson, Herodotus, 1, 552, 553. SEE EUPHRATES.