THE SOURCE OF THE NILE. 675 
floods; and therefore, on the firft confideration, this annual 
and equal increafe muft be impofirble. 
At Bafboch, before the Nile enters Sennaar, I made feve- 
ral hundred trials upon its fediment, as it then:came down 
from the cultivated country of Abyffinia; I thereby found 
this fediment furprifingly fmall, being a mixture of fat 
earth, and a fmall quantity of fand. At the junction of the 
Nile and Aftaboras I did the fame, taking up the water 
from the middle of the ftream, and, having evaporated it 
afterwards, I found little more fediment than at Sennaar; 
the water was indeed whiter, and the greateft part of the 
fediment was fand. I repeated this experiment at Syené 
with the utmoft attention, where the Nile leaves Nubia, and 
enters Egypt, and I found the quantity of fediment fully 
nine times increafed from what it was at Sennaar, and in 
it only a trifle of black earth, all the reft being fand. The 
experiment at Rofetto was not fo often repeated as the 
others; but the refult was, that, in the ftrength of the in- 
undation, the fediment confifted moftly of fand, and, to- 
wards the end, was much the greater part of earth. I think 
thefe experiments conclufive, as neither the Nile coming 
frefh from Abyffinia, nor the Atbara, though joined by the 
Mareb, likewife from the fame country, brought any great 
quantity of foil from thence. 
Ir was at Syené that the water fhould have been moft 
charged with mud, for all the acceilion it was to bring to 
Egypt was then in its ftream ; butthere the chief part of the 
fediment was fand, fanned and ventilated with perpetual 
hot winds, and fpread on the furface of the burning defert, 
never refrefhed with the dew of heaven. In that dreary 
4Q2 defert, 
