November 23, 1899] 



NA TURE 



75 



anena which come under its scope, even omitting (as 

 he does) thermo-electric phenomena and thermo-elasti- 

 city, cannot fail to attract students to this fascinating 

 branch of mathematical physics. G. H. Bryan. 



THE CONTINUITY OF THE ERYTHKEAN 

 RIFT VALLEY. 



Seconda Spedizione Bottego. VOmo. Viaggio d^Espior- 

 azione nelV Africa Orientale. By L. Vannutelli and C. 

 Citerni. Pp. xvi + 650 ; 1 1 plates, 9 maps, and 

 numerous illustrations. (Milano : Hoepli, 1899.) 



THE Erythrean Rift Valley has been proved con- 

 tinuous across forty degrees of latitude from the 

 Jordan to the south of Kilima Njaro, except for a 

 possible break of about 250 miles between Lake Rudolf 

 and the basin of the Havvash. Whether the valley is 

 broken in that district depends on the course of the Omo 

 and its relations to the river known as the Nianam, 

 which flows into the northern end of Lake Rudolf. The 

 name Omo was introduced into geography by Leon des 

 Avanchers in 1858, for a river which drains part of the 

 southern slope of Abyssinia, a little to the west of 

 Menelik's capital at Addis Abeba. The river had been 

 known long before, for it is the Zeb^ of the seventeenth- 

 century Jesuit missionaries. The upper part of its course 

 was described by Ludolf in his "New History of 

 Ethiopia" (1681) from information supplied by the Abba 

 Gregorius. But the lower course of the river was quite 

 unknown. Ludolf believed that it flowed eastward and 

 entered the Indian Ocean near Mombasa. 



Bruce in the following century accepted this hypo- 

 thesis and called the river the " Zebe or Quilimancy," 

 the latter being an old name for the Ozi, a river which is 

 a parasite of the Tana.^ 



But in the present century Frederick Ayrton and 

 Antoine d'Abbadie claimed the Zeb^ as one of the head- 

 streams of the Nile. This view was supported by 

 Petermann, who held the Zebe to be a tributary of the 

 Sobat, and by Bonala, who believed that it flowed into the 

 X'ictoria Nyanza, and was therefore the remotest source 

 of the Nile. Harris, McQueen, Schweinfurth and Cecchi 

 on the contrary supported the theory that the Zebd 

 belonged to the Indian ocean drainage, and rendered 

 this view more plausible by identifying the Omo as one 

 of the sources of the Juba. In 1889 and 1890 a fresh 

 explanation was introduced by Teleki and von Hohnel's 

 discovery of Lake Rudolf, and Borelli's descent of the 

 Omo towards that lake, into which native rumour 

 asserted that the river flowed. The work of these 

 travellers seemed to disprove both the old theories ; 

 but Dr. Donaldson Smith, after his important journey 

 to Lake Rudolf in 1895-6 again advocated the con- 

 nection of the Omo and the Juba. What was known of 

 the levels of the three rivers seemed fetal to this idea, 

 and in a review of Donaldson Smith's book in Nature 

 (July I, 1897) It was maintained that the Omo and the 

 Juba could not be connected, and that "the Omo must 

 continue as the Nianam and flow into Lake Rudolf." 



1 Bruce is quoted on p. 4 of the present work as having regarded the ZeW 

 as one of the head-streams of the Nile ; but that was only the view of some 

 of his editors. Bruce himself did not reach the Zebfe ; he does not appear 

 to mention it in his narrative, and his map marks it as separated from the 

 Nile tributaries. 



In order to settle this long controversy Vittorio 

 Bottego, an explorer well known from his work in the 

 Juba basin in 1891-2, proposed an expedition which was 

 fitted out under the auspices of the Italian Geographical 

 Society. Thanks to the energy of this Society, Bottego 

 started in October 1895 ^^^^ Barawa on the Somali 

 coast at the head of a powerful caravan of four European 

 officers, 250 natives, 120 camels, and 300 mules. 



The expedition left Barawa in October 1895, and 

 marched across Italian Somaliland, along a route 

 parallel to the river known to geographers as the Juba. 

 The authors, however, speak of it as the Fiume Ganana, 

 which being interpreted is the " River River." 



The first long halt was at Logh, the principal com- 

 mercial centre in the Juba valley. After building a fort 

 and a trading station at that town the expedition crossed 

 the " Fiume Ueb " (which also means " River River "), and 

 marched north-westward up the course of the principal 

 tributary of the Juba. The explorers found that this 

 river dwindled rapidly, and long before they reached its 

 head found that it could have no connection} with the 

 Omo. Leaving the Juba basin, the expedition care- 

 fully explored Lake Abbaia, which it is proposed to call 

 Lagho Regina Margherita, and then proceeded to its 

 main objective the Omo. The river was reached near 

 the point to which Borelli had tracked it from the north. 

 Bottego, after his former expedition, inclined to the view 

 that the Omo was one of the Nile tributaries ; but after 

 following the river for some distance westward it suddenly 

 bent southward, became the Nianam of von Hohnel, and 

 entered Lake Rudolf The Omo problem was settled. 



While resting in the food country at the northern end 

 of Lake Rudolf, the expedition mapped its western 

 shores, and collected much fresh information regarding 

 the Reshiat, who are described under the name of the 

 Gheleba. This interesting tribe was first described by 

 von Hohnel. From the facts and figures given by 

 Vannutelli and Citerni it appears probable that the 

 people are Nilotic negroes, allied to the Njempsians, and 

 altered by Galla intermixture. 



After mapping the western shores of Lake Rudolf the 

 expedition proceeded up the second river, which von 

 Hohnel had described as entering the northern end of 

 the lake. The existence of this river has, however, been 

 denied. Bottego's party followed the river, which it is 

 proposed to rename the Fiume Maurizio Sacchi, to the 

 north-west ; but its course is short, and the expedition 

 climbed the water-shed into one of the tributaries of the 

 Sobat, For this tributary the authors propose to restrict 

 the name of Juba. They followed this river to the 

 north-west until it left the Ethiopian highlands near its 

 junction with the group of rivers that unite to form the 

 Sobat. They traversed the swamps of this region to a 

 point some forty miles from the old Egyptian station ot 

 Nassur. Having thus settled the relations of the Sobat- 

 Juba, the expedition returned to the Abyssinian high- 

 lands on the home trail. They entered the Sajo country, 

 which is ruled by one of Menelik's governors. Bottego 

 sent a polite request for permission to return to Massowah 

 either across the Amhara province around Lake Tsana, 

 or through Shoa, or by any route which might be 

 suggested. The expedition was invited to visit the 



NO. 1569, VOL. 61] 



