OPTICAL ILLUSION IN THE DESERT. ^41 
expanse of its bed, we saw that its more usual current must flow 
at treble the width. After gaining its western shore we again 
rose upon the sandy plain, which we crossed in a direction 
south 80° west; and continued to that point till after four hours’ 
travelling we stopped at a half-erected khaun, about four far- 
sangs from Bacoubi, to rest our invalids and beasts of burthen. 
Our carpets were spread under arched recesses, yawning with 
many a yet undefended aperture through which the wild prowl¬ 
ers of the waste, or more ready whirlwinds of burning sand which 
often sweep these solar regions, might find unobstructed ingress. 
However, our sojourn was not disturbed by either ; and those 
who required it, enjoyed a repose of four hours. This unfinished, 
half ruinous structure was begun by order of Mahmoud AJi 
Mirza, for the convenience of his Persian pilgrims journeying to 
the shrines of Ali and Hossein ; and it is to be lamented, that 
so good a commencement has proceeded no further. 
October 14th.—At two o’clock this morning we resumed our 
march, lit by the stars and moon. The bright concave above, 
and the far-spread Chaldean plain below, without other visible 
object to distract the eye from contemplating the planetary 
heavens, possessed a sublime monotony, which seemed to tell 
the same divine tale to the present traveller under its arch, that 
it told some thousand years ago to the first astronomers of man¬ 
kind. In the midst of these meditations, a little before morning 
broke, I observed, in a direction north-west, an elevated stream 
of water, which, from its situation, must be the Tigris. Its sur¬ 
face was brilliantly illuminated by the moon ; but the longer I 
kept my eye fixed on this noble river of many interests, the 
more my surprise became excited at the extraordinary height of 
its waters above the level of the desert, till at last I began to 
i i 
VOL. II. 
