The lluwenzori Kange. 



at first siglit l)e 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. ('^) 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 Rhaptum (^•^) : "After this he (Maiiuus) says that 

 in the voyage between the Aromata and Rhaptum promontories a certain 

 Diogenes . . . was in the neighbourhood of the Aromata, driven by the 

 northern winds, and having on his right hand the Troglodytica arrived in 

 five days at the lakes where the Nile rises, these lakes being someAvhat more 

 to the north than Rhapta." (^'') 



In this the geographer of Tyre is conti-adicted Ijy 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 Rhapta, a 

 place of great consequence and spoken of by Ptolemy as a metropolis ('Pa-rà 

 /(*/7/jo-o\<v), is placed 1)y him under the latitude of 7" S. {^•), while, on the 

 other hand, he was naturally inclined to believe that the two lakes lay due 

 west of Rhapta, or nearly so, he accordingly gave to the eastern lake the same 

 latitude of 7' 8. and to the western 6' S. And I may here remark that, 

 the position assigned l)y Ptolemy to Rhapta being almost exact (^*^), 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 Rhapta is 71', and that of the eastern lake is 

 given as 65 ', the diiierence (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'). Tha 14 degrees of longitude that 

 extend from the western lake (longitude 57" according to Ptolemy) to Rhapta 

 (71') are reduced to IT 40', and this scarcely exceeds the real difference 

 (39-29° 30') by r 10'. 



The almost identical results at which we arrive by taking as centres of 



293 



