The Ituwenzori Range. 
at first sight be explained by admitting that those notions about the hydro- 
graphic relations might have been gathered by Ptolemy with the help of 
itineraries made along the valley of the river itself and generally in the 
direction from north to south. ( u ) Only, as Ptolemy himself says, these 
particulars were extant, at least in part, in the work of Marinus of Tyre, 
who in his turn had derived them from one of the then recent reports of the 
first Greek navigators of Egypt, who frequented the markets of East Africa 
from Cape Aromata to Cape Ehaptum ( 15 ): “ After this he (Marinus) says that 
in the voyage between the Aromata and Ehaptum promontories a certain 
Diogenes . . . was in the neighbourhood of the Aromata, driven by the 
northern winds, and having on his right hand the Troglodvtica arrived in 
five days at the lakes where the Nile rises, these lakes being somewhat more 
to the north than Ehapta.” ( lli ) 
In this the geographer of Tyre is contradicted by Ptolemy, who a little 
further on says : “ The lakes whence rises the Nile are not near the sea, but far 
more inland on the Continent.” This is an important correction very probably 
suggested to Ptolemy by the reports of those Greek seafarers, since the places 
from time to time visited by them on the east coast of Africa were not only 
important from the commercial standpoint, but also as so many centres 
whither fresh and numerous particulars could not fail to come to hand about 
the geographical and natural conditions of the inland regions. No wonder, 
therefore, if amongst those particulars was also that most important one 
regarding the existences of two lakes; and as the emporium of Ehapta, a 
place of great consequence and spoken of by Ptolemy as a metropolis ('P«7 j-t4 
fupjjo-oXi'i), is placed by him under the latitude of 7 S. ( K ), while, on the 
other hand, he was naturally inclined to believe that the two lakes lay due 
west of Ehapta, or nearly so, he accordingly gave to the eastern lake the same 
latitude of 7° S. and to the western 6° S. And I may here remark that, 
the position assigned by Ptolemy to Ehapta being almost exact ( ls ), we may 
consider this place as a second centre of observations, such as those above 
described as having been carried out for Alexandria. Now, according to the 
tables, the longitude of Ehapta is 71°, and that of the eastern lake is 
given as 65°, the difference (6 degrees) being with the reduction 5 , and that 
is the difference between the mean longitude of the mouth of the Pangani 
(39 ) and that of Lake Victoria (33° 15'). The 14 degrees of longitude that 
extend from the western lake (longitude 57 J according to Ptolemy) to Ehapta 
(71°) are reduced to 11° 40', and this scarcely exceeds the real difference 
(39 -29° 30') by 2° 10'. 
The almost identical results at which we arrive by taking as centres of 
293 
