3i8 TRAVELS IN AFRICA, 
itfelf to them, but of topical applications to remove a local com- 
plaint. If any thing be applied in thefe JiiiJ[io7ii (dyfophthalmia) 
it is generally kohhel (calx of tin mixed with fheep's fat) or 
tuttij a ftill more powerful aftringent, applied in coarfe powder, 
and naturally tending to increafe rather than to allay the irri- 
tation. 
When thus incommoded, the Egyptians of the lower clafs 
efteem water pernicious, and therefore rarely wafh their eyes ; 
but as the collected duft begins to caufe an uneafy fenfation, 
apply their fingers or a coarfe cotton cloth to remove it. The 
higher orders, who are neat in their perfons, and regular in their 
ablutions, are rarely obferved to be greatly harafTed by this com- 
plaint. And the progrefs of the diforder, when in its nafcent 
ftate, has feveral times been flopped, under my obfervation, by 
the ufe of rofe-water, folution of facchar. faturn. &c. as in other 
places. 
But as no fmgle one of thefe caufes, nor even all of them 
together, appear fufficient to account for all the phenomena, 
another, more powerful, is to be fought ; and none fuggefts 
itfelf more opportunely than that alleged by Savary, who ima- 
gines that the defedt of vifion is principally brought about by 
the habit of being expofed to the noQurnal air during the fum- 
mer, at which feafon a heavy dew falls, and a great tranfition 
happens from the heats of the day. In faft, if the face of thofe 
who lleep expofed be not completely covered, an itching and 
unpleafant fenfation is always felt in the eyes at rifmg. 
It 
