current and also its depth are considerably diminished through the numerous canals that form an outlet for its waters. Of its entire length, 1780 miles, it is navigable only for a small distance, cataracts forming a hindrance in its northern course and sandbanks in the south. In consequence, it never became at any time an important avenue for commerce, and besides rafts, which could be floated down to a certain distance, the only means of communication ever used were wicker baskets coated within and without with bitumen, or some form of a primitive ferry for passing from one shore to another. An entirely different stream is the Tigris--a corrupted form of 'Idiklat.' It is only 1146 miles in length, and is marked, as the native name indicates, by the 'swiftness' of its flow. Starting, like the Euphrates, in the rugged regions of Armenia, it continues its course through mountain clefts for a longer period, and joined at frequent intervals by tributaries, both before it merges into the plain and after doing so, the volume of its waters is steadily increased. Even when it approaches the alluvial soil of the south, it does not lose its character until well advanced in its course to the gulf. Advancing towards the Euphrates and again receding from it, it at last joins the latter at Korna, and together they pour their waters through the Persian Gulf into the great ocean. It is navigable from Diabekr in the north, for its entire length. Large rafts may be floated down from Mosul to Baghdad and Basra, and even small steamers have ascended as far north as Nimrud. The Tigris, then, in contrast to the Euphrates, is the avenue of commerce for Mesopotamia, forming the connecting bond between it and the rest of the ancient world,--Egypt, India, and the lands of the Mediterranean. Owing, however, to the imperfect character of the means of transportation in ancient and, for that matter, in modern times, the voyage up the stream was impracticable. The rafts, resting on inflated bags of goat or sheep skin, can make no headway against the rapid stream, and so, upon reaching Baghdad or Basra, they are broken up, and the bags sent back by the shore route to the north. The contrast presented by the two rivers is paralleled by the traits distinguishing Upper from Lower Mesopotamia. Shut off to the north and northeast by the Armenian range, to the northwest by the Taurus, Upper Mesopotamia retains, for a considerable extent, and especially on the eastern side, a rugged aspect. The Kurdish mountains run close to the Tigris' bed for some distance below Mosul, while between the Tigris and the Euphrates proper, small ranges and promontories stretch as far as the end of the Taurus chain, well on towards Mosul.