'The Expedition for the survey of the rivers Euphrates and Tigris, carried on by order of the British government, in the years 1835, 1836, and 1837; preceded by geographical and historical notices of the regions situated between the rivers Nile and Indus. In four volumes. With fourteen maps and charts, and embellished with ninety-seven plates, besides numerous wood-cuts. Volume the first.' [‎572] (663/905)

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RIVERS OF ARABIA.
[CHAP, XXII.
a body of fresh water, and even salt lakes are almost equally
rare, the Bahr-el-Merj, eastward of Damascus, the lake near
Palmyra, and one or two elsewhere, being all that are known
to us at present.
Except the Euphrates, which washes Arabia for about 977
miles, and a stream rising eastward of San'a, which is said to
The Sayi or pass through Hadramaut to the sea at Kaijah, also the Sayl
or Bicheh, which flows from the province of Asir eastward
through the valley of pawasir, and onward into lake Salome,
it may be said that there is no other considerable river within
its limits, and there are comparatively few rivulets. It is
true that the valleys now and then have large streams which
are fed by the mountain dews, but for the most part these
exist only in the winter season, and they are confined chiefly to
the western side of the great range forming the watershed The boundary between adjacent drainage basins.
which so unequally divides the territory. On the other side,
as at Nedjd, they are lost in plains, marshes, or lakes. 1
Wadis. The workings of such winter torrents produce valleys, and
these, whether dry or containing water, whether barren or
cultivated, the Arabs call either ghadirs or wadis ; they are
very numerous, and are altogether the most remarkable fea
tures of the country. The wadis have hills on both sides,
rising above the surface of the adjacent plain ; the ghadir, on
the contrary, is only a hollow in the plain. 2
Mirage. The distress occasioned in Arabia by a deficiency of water is
frequently increased by the tantalizing appearance presented
by the sirab or mirage in that country. The light refracted
in the rarified air immediately above the heated ground gives
rise to the resemblance of an extensive lake, and the thirsty
traveller, advancing towards it, finds the flattering delusion
recede before him. In the early part of the morning, while
some dew remains on the ground, the perception is remarkably
strong; every object is then also magnified, so that shrubs
appear as trees, and under them frequently appear their images
inverted, as if reflected from the surface of water.
With the exceptions of the mountains of Yemen those of
1 Captain Sadleir's Journey, vol. III., p. 464-469, Bombay Literary Society.
2 Burckhardt's Travels in Syria, p. 666.