222 THE POPULAR SCIENCE MONTHLY. 



about seventy feet liigh, mounds strewed with brolien pottery, and a 

 vast number of water-cisterns now choked with earth. 



In Africa, Lieutenant Cameron, of the Livingstone Relief Exi)edi- 

 tion, has made an important discovery which fixes the source of the 

 Nile within known limits, and which, there is every reason to think, 

 will connect the net-work of lakes and rivers of the water-system that 

 Livingstone was investigating, with the great rivers that flow to the 

 western coast of Africa, and probably with the Congo. Livingstone 

 and Stanley had settled the fact of Lake Tanganyika's being con- 

 nected with Lake Albert N'yanza on the north by a river flowing into 

 Tanganyika. The natives informed them that a river flowed out of 

 Tanganyika at its southern extremity, which, if true, showed that Lake 

 Tanganyika had no connection with the Nile. This oiitlet Lieutenant 

 Cameron has found on the western side of the lake, about a third of 

 the way up its length. He went into the river about five miles, when 

 Ijis boat was stopped by grass and rushes. The natives informed him 

 that this river flowed into the Lualaba, the river that Livingstone had 

 been following up when Stanley found him. From information got 

 from the natives, Lieutenant Cameron believes that the Lualaba is 

 connected with the Congo, and has started to ascertain the fact. If 

 he should be successful, and return through the Congo to the western 

 coast, it will be one of the most important geographical achievements 

 ever accomplished in Africa. He ascertained the elevation of Lake 

 Tanganyika to be 2,710 feet above the sea. Dr. Nachtigal has re- 

 turned from an exploration of five years in Central and Eastern Sou- 

 dan. He says the curse of the country he traversed is the internal 

 slave-trade. It has depopulated large tracts, and the wretched fugi- 

 tives are now driven to sell each other as a means of subsistence. He 

 saw a caravan of 1,000 of these unhappy wretches chained, while they 

 were driven to the distant market of Kuka on Lake Tchad, the drivers 

 mercilessly cutting the throats of those who were, even under the 

 lash, unable, from exhaustion, to continue their terrible march. The 

 Libyan Desert has been explored and found to be the most sterile part 

 of the Sahara, beiirg a dried-up l)asin of a shallow sea below the level 

 of the Mediterranean, the present surface of which was found to be a 

 dry chalk plateau, like the Swabian Alps. A French expedition is 

 making preliminary investigations as to the feasibility of M. Lesseps's 

 project for creating an inland sea south of Tunis. The project is op- 

 posed by many familiar with this part of Africa, not only as useless, 

 but it would have an injmious efiect on the climate of the south of Eu- 

 rope, and also destroy the great source of wealth in this part of Africa, 

 the cultivation of the date-tree. The existing commerce can be suffi- 

 ciently carried on by caravans, so that the commercial results of the 

 undertaking would never justify the enormous expenditure, which is 

 estimated at 24,000,000. Along the western coast of Africa, explora- 

 tions have been unusually active. Dr. Giissfeldt made a journey up 



