With the exception of the drainage of the Ghazni river, which collects in the Abistada marsh, and the drainage of the Calát tablelands, which flow to the desert north of the Mushti range, all the rivers within the area indicated flow towards the Sistan basin, at the south-western extremity of the Kandahar plain, though they do not all reach it. All the rivers and rivulets from the eastward and southward flow to the stream of the Helmand, whilst those of Sabzwár and Ghor flow in separate streams, all to meet in the Sistan basin. So it is in the Afghanistan half of the region; and a similar system, though on a much less extensive scale, is found to hold in the Persian half. Thus all the streams between the Alwand range of Hamadán on the west, and the Alburz on the north-east, converge to the south-east corner of the Persian tableland, where they expand themselves on the surface of the great salt desert north of Kirmán. At least, such is the case if any reliance is to be placed on the statements of my Persian informants, whose testimony I am willing to believe from my own observations as to the general course of the streams and the lie of the land; for I have not seen this shown on any map. The river Khusp of Birjand, the Yúnasi river, the Kál Shor of Nishabor and Sabzwár, the Kál Abresham and others on to Tehran, all flow direct on to the salt desert, and the streams crossed on the road from Tehran to Hamadán all flowed in the same direction. The great salt desert of Persia, called the Daryáe Kabír, or “the vast sea,” extends all along the western side of the Khorassan hills, from Nishabor in the north to Kirmán in the south, and sinks to its lowest level in the latter direction, opposite to the Sistan basin, on the other side of the intervening mountain range. So that the water systems of the two countries converge towards each other, and at some remote period probably formed lakes or swamps on either side of the mountain range dividing them, where it joins the great southern border of the region. The water system of the country, to the north of this dividing range, belongs to the hydrographic system of Turkistan, and is beyond the limits of the region I am describing. Its rivers all flow towards the lowest part of the desert tract lying between the lower course of the Oxus and the Caspian, and there end in the swamps of Tajand and Marv. The principal of these streams are the Murgháb, the Hari Rúd, and the river of Mashhad. With the exception of the Helmand and Farráh Rúd in Afghanistan, none of these streams always reach their destination. They only do so in periods of excessive flood; usually their waters are dissipated by evaporation, absorption by the porous soil, and by diversions for purposes of irrigation, long before they can reach their terminal receptacles.