494 MORAL AND POLITICAL 
caravan of two thousand men, with eighteen hun- 
dred camels, entirely perished. * Another source 
of destruction has been supposed to arise from the 
clouds of moving sand, which sweep occasionally 
over the surface of this immense plain. Mr 
Browne, however, is of opinion, that these are 
never of such density, as that a caravan can be 
buried beneath them ; and that the appearance of 
such a catastrophe, is produced merely by the sand 
accumulating over the bodies of men and animals, 
which have perished from other causes, t 
Cairo sends three caravans into the interior of 
Africa. One goes to Sennaar, sometimes by the 
route from Syene across the desert of Nubia to 
Gerri, which was traversed by Bruce, while at 
other times it strikes off at Monfalout, and passing 
by El-Wah, Sheb, and Selyme, rejoins the Nile at 
Moscho. Poncet accompanied this caravan. The 
second caravan goes to Darfur, and follows the 
same route as that last mentioned as far as Selyme, 
when, instead of striking off to the Nile, it con- 
tinues south, with a slight declination to the west. 
These two caravans travel only once in two or 
three years, and seldom exceed five hundred per- 
sons. The third caravan, from Cairo to Mour- 
zouk, is on a greater scale, and performs, in gene- 
* Jackson's Account of the Empire of Morocco, p. 242. 
f Travels, Ch. IV. 
