and give place to an arid plain, featureless as the open sea. From this point to Kut, 145 miles, there is a gradual enlargement in the size of the river-bed, though the stream, except in the flood season, does not perceptibly: increase in volume. Sinuosity varies, but in places, such as the neighbourhood of Filaifilah, is very marked. Above Kut, from which the distance to Baghdad by water is no less than 220 miles, though at normal seasons the volume of the stream remains fairly constant, the channel grows steadily larger. The sinuosity is extraordinary, taking the form of series after series of extravagant loops, quite rhythmic in their alternation. In brief, the Tigris in its lower stages-the four hundred miles or so which it traverses between Baghdad and Ezra's Tomb-differs from all other rivers, except its twin-sister the Euphrates, in that while it receives only two tributaries, one considerable stream, the Diyalah, just below Baghdad, the other the insignificant Wadi, below Kut-it throws off five huge effluents, besides innumerable minor channels, and the further it advances the smaller it becomes.

The Euphrates in the same portion of its length receives no tributary and reaches an even more pronounced state of degeneration. In two areas it breaks down altogether and ceases to be a river. The first of these is the tract known as Shamiyah, which lies between Kufa and Samawah. Here the Euphrates disintegrates into a thousand petty waterways, which are constantly shifting. They run between great marshes and huge stretches of open water, until near Samawah the remnants of the streams reunite, only to part again about 80 miles further down, in the Muntafik country below Nasiriyah, where they form the Hammar Lake. This lake is a waste of shallow water, even in the lowwater season exceeding 1000 square miles in extent; and from it one arm comes to join the Tigris at Qurnah, while the other and far larger branch, known as the Qurmat 'Ali, enters the Shatt-al-'Arab just above Basrah. In the reaches immediately above Qurnah both rivers are considerably fortified by return streams from the marshes. But the water which comes back returns clear, having dropped its silt in the marshes, where also it undergoes an enormous loss through evaporation.

The present courses of both rivers are no doubt

recent, but their degeneration is no new thing. Archæological discovery, historical record, and Mesopotamian topography concur in testifying to the recurrence of similar conditions and to the uniformly capricious behaviour of the two rivers throughout the centuries since man first became a dweller in Mesopotamia. In more recent times we have glimpses of the same activities. It will suffice to quote two examples. In 1837 Colonel Chesney, of the Royal Engineers, searching for a mail-route between India and England, made a voyage of scientific exploration on the twin rivers. He took Soundings wherever he went, and made accurate measurements of each day's run. In what are now the Narrows, Chesney records a depth of from 2 to 6 fathoms and a width of from 200 to 400 yards. He also speaks of 'high and well-wooded banks' in the same region. Moreover, the distance from Qurnah to Baghdad by water, as measured by Chesney, was less by 22 miles than it is now. This last difference, it may be noted, is chiefly in the reaches between Kut and Baghdad, and may no doubt in a large measure be ascribed to the action of Midhat Pasha, Wali of Baghdad, who in the early seventies dammed the Saklawiyah channel, which leads from the Euphrates above Fallujah to the Tigris opposite Baghdad and used to take off a large portion of the annual flood from the one river to the other. This well-intentioned act, designed to keep the capital from being flooded, caused incalculable damage lower down in the Euphrates, and by suddenly depriving the Tigris of supplies, to which its bed had adapted itself, caused the channel to shrink in capacity, rise in level, and increase in length.

To return to the Narrows-the late Mr J. G. Lorimer, LC.S., for some years British Resident in Turkish Arabia, a singularly careful and accurate observer, writing in or about 1907, says of the Tigris:

'In the swampy tract from Qurnah up to 'Azair (Ezra's Tomb) there is a depth of not less than 12 feet, but some of the turns are so sharp that a vessel more than 220 feet in length could not negotiate them. In the marshes proper, from 'Azair to Qal'at Salih, the river is at its narrowest with a navigable channel of only 25 to 50 yards; in this section. there is no place where a steamer of 220 feet could go about,

and two steamers cannot pass one another without one tying up to the bank. The channel here is shallow in a low river. The unsatisfactory character of this reach is due to the numerous canals-some of them 20 to 30 yards across at the head-between Qal'at Salih and 'Amarah town, which, after the river has lost nearly half its water above 'Amarah, absorb perhaps one-third of the remainder; conversely the improvement below the marshes is due, as already indicated, to the return of part of the water by circuitous courses to the parent stream. The channel through the marshes is deteriorating and has lost about one-fourth of its breadth during the last ten years. Above the marshes the depth and width of the channel are both as a rule satisfactory, and from 'Amarah town to 'Ali-ash-Sharqi there is always 8 feet of water even with a low river.'

The mention of eight feet of water as constituting a satisfactory river above 'Amarah proves that the shallow river, below Qal'at Salih, had a less depth; indeed, in 1915 our boats had to contend with depths of four feet and less in many parts of the Narrows. The measurements of our engineers, too, taken in 1915 and subsequent years, showed that the effluents were then taking considerably larger fractions of the total supply than those named by Mr Lorimer. In other words, the process of deterioration had continued after he wrote,

The contrast between this and the conditions depicted by Chesney as obtaining in the same region cannot fail to strike the imagination. As for the well-wooded banks of which Chesney speaks, we know how they became denuded. The wood went into the maw of Lynch's steamers, the pioneers of British trade. But Chesney also calls the banks high. How did they become low, as they now are, almost awash with the waters of the river at all seasons? There can have been no general subsidence of the country. The only alternative is that the river has silted up, and in so doing has raised its bed-level until its waters, even in the low season, are always lipping over the banks. Indeed, in this region the flood makes little difference to the size of the stream, though it affects enormously the area of the adjacent marsh. All the extra water that the flood brings, or nearly all, has already slipped out into the marshes before the river reaches Qal'at Salih, and the

residue remaining in the shrunken bed is in volume, though not in rate of flow, nearly constant.

The phenomenon above described is, I believe, unique. For we have here no ordinary delta such as many rivers, for example the Nile in Egypt, the Po¡ and the Adige in Italy, have made for themselves in their last lap to the sea. On the contrary, the rivers of Mesopotamia, after disintegrating and reuniting many miles inland, pour the remnant of their waters into the Persian Gulf by a single mouth. The explanation of this peculiarity, though possibly not the whole explanation, is, doubtless, that given by Mr Lorimer. It is the effluents which have caused and are causing the disintegration of the rivers. But how come they to have this effect? For it is obvious that unless there were something peculiar in Mesopotamian conditions, the mere digging of sidechannels out of the river bed would have no more serious consequences in the valley of the Tigris than it would have in the valley of the Thames. This peculiarity, as contrasted with the Egyptian Nile, is vigorously described by Sir William Willcocks in his book on the 'Irrigation of Mesopotamia,' though his obiter dictum on the growing of cotton has been falsified by subsequent experiment.

'The problems,' writes Sir William Willcocks, 'whose successful solution will restore Babylonia to its ancient prosperity are far more difficult of solution than those which faced the irrigation engineers in the Nile Valley. Of all the rivers in the world the Nile is the most gentlemanly. It gives ample warning of its rise and fall; is never abrupt; carries enough of sediment in flood to enrich the land without choking the canals; is itself free of salt; has its annual flood in August, September, and October, securing both summer and winter crops; traverses a valley with a climate mild enough to allow of Egyptian clover in winter and Egyptian cotton in summer; and flows between sandstone and limestone hills, which provide an abundance of building materials. 'The Tigris and Euphrates rise without warning; are always abrupt; carry five times the sediment of the Nile; have their annual flood in March, April, and May, too late for the winter and too soon for the summer crops; traverse a country where the temperature rises to 120 degrees in summer and falls to 20 degrees in winter, and where both Egyptian cotton and Egyptian clover are out of the question;

have a considerable quantity of salt in solution; and flow between degraded deserts of gypsum and salted marl. . .

'The Tigris-Euphrates delta is strangely flat. Baghdad,TM removed 500 miles from the sea, is only 120 feet above sealevel. Opposite Baghdad the Euphrates is 25 feet higher than the Tigris. Between the two rivers runs a regular valley, across which are carried the giant banks of the ancient canals. Though the slope of the country longitudinally is very slight, the traverse slopes away from the rivers are one in a thousand, or five times as steep as those of the Nile Valley. If the Nile breaches its banks in flood, it can be ti brought back after the flood to its old channel without serious difficulty; while a very serious breach on the Tigris or Euphrates has been followed by the river completely leaving its channel and forming a new one miles away, after inundating the whole country. Such was Noah's flood in the early days of the world's history.

'In the Tigris-Euphrates delta we must never forget that we are in the country of Noah's flood; and as in antiquity, so to-day, the foundation on which will be laid the structure of Babylonian prosperity will be the protection of the country from floods; and the more thorough the protection, the more substantial will be the prosperity.'

The Mesopotamian rivers in fact, with their gentle longitudinal and steep transverse slopes, run upon causeways of their own making, as any one who takes his stand upon their banks may see for himself with the unaided eye. Other rivers, no doubt, do this in their deltas. But is the whole vast expanse of Mesopotamia south of Hit and Samarrah correctly described as a delta? And if not, why and how have the rivers behaved in so strange a fashion? Among the irrigation engineers who worked in the country during the British military occupation another explanation has been put forward. The following extracts are taken from a report by Major Walton, of the Indian Public Works Department, who was employed in Mesopotamia from 1915 to 1918:

'For the last six thousand years-or maybe more,' he writes, since irrigation of any sort was first practised in the country, the hand of man has been applied, not scientifically, but very unscientifically, to the rivers. It has been the continuous application of effort and not necessarily any sudden concentration that has brought about the present

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