Page:The American Cyclopædia (1879) Volume XII.djvu/461

 NILE 447 S. of the Tzana or Dembea lake in Abys- sinia, in lat. 10 58' N., Ion. 36 50' E., at an altitude of 6,000 ft. above the sea. level. Thence the river flows about 80 m. N. W. into the lake itself on its W. side, through it, and out again on its S. E. side. Its current is so rapid that it scarcely mingles its waters with those of the lake. Flowing southward in many cataracts, it winds around the moun- tainous region of Gojam till by a bend ' to the northwest it returns to within about 70 m. of its source. While forming this remark- able curve, which makes Gojam a peninsula, the Abai receives numerous streams from the mountains of that peninsula. The total length of the Blue Nile, measured from the sources of the Abai, is supposed to be about 800 m. The river is navigable as far as the district of Fazogle, between the llth and 12th paral- lels of latitude, about 1,500 m. from the Medi- terranean. The superior magnitude of the Bahr el-Abiad unquestionably entitles it to be considered the Nile proper ; and a correct de- termination of the sources of this river has justly been regarded as the greatest geograph- ical problem of modern times. It has been at least approximately solved by the discovery of two great lakes lying side by side directly under the equator, and known respectively as the Victoria N'yanza and the Albert N'yanza. The first of these equatorial fresh-water basins was discovered on July 30, 1858, by Capt. J. H. Speke of the British Indian army, who in 1862 explored its western and northern margin, in company with Capt. (now Col.) J. W. Grant. According to his observations, it is 3,308 ft. above the sea level, and extends from lat. 2 24' S. to 21' N., a distance of nearly 200 m., with its westernmost shore in about Ion. 31 30' E., although by far the largest portion of the lake lies E. of the 32d meridian. The mea- surements taken on his first journey, however, showed an elevation of 3,740 ft. above the ocean. From these observations those of Ba- ker, who visited the Victoria Nile in 1864, dif- fer materially. (See N'YANZA.) The width of the lake is unknown. Its outlet, the Somerset river or Victoria Nile, supposed by Speke to be the Bahr el-Abiad itself, flows northward and westward into the Albert N'yanza, in lat. 2 16' N., on the E. shore of that lake, about 30 m. S. of its N. E. extremity. On March 14, 1864, Mr. (now Sir) Samuel Baker discovered this second great lake, the Albert N'yanza, whose outlet is the White Nile of Egypt, of which the lake had hitherto been supposed from native report to be merely an extensive but sluggish backwater. The most southerly point which he visited on its E. shore is proba- bly not more than 100 m. N. W. of the Victo- ria N'yanza. The Albert N'yanza is 2,720 ft. above the ocean, according to Baker's corrected observations. The width of the northern por- tion is estimated at 60 m. ; it narrows to 17 m. near the exit of the Nile, which is not far from lat. 2 45' N., Ion. 31 30' E. From this 606 VOL. xii. 29 point the lake extends some distance N. W., but how far is not known. The only knowl- edge of its prolongation southward which we possess is derived from native accounts, which represent it as extending to between lat. 1 and 2 S., where it is said to bend W. Its shores so far as known are for the most part rocky and mountainous. The existence of these lakes confirms to some extent the notions of the geographer Claudius Ptolemy, who in the 2d century of our era stated the sources of the" Nile to be in two lakes lying N. of a snowy range which he calls the mountains of the Moon, and which he describes as extending for 10 of longitude along the parallel of lat. 12 30' S. From the snows of these moun- tains were principally derived the waters of the two lakes, which were due N. of the moun- tains, the western lake in lat. 6 and the east- ern in 7 S., with a distance between them of 8 of longitude. Owing to the imperfection of astronomical science in his day, his lati- tudes and longitudes are incorrectly given. Notwithstanding 'the discovery, however, that from the Albert N'yanza comes the Nile proper, and that the Somerset river, flowing from the Victoria N'yanza into this more northern lake, must be regarded as at least an important trib- utary, if not the upper course of the veritable Nile, the ultimate sources of the great river still remain undetermined. There is every in- dication that they lie S. of the two great equa- torial lakes, and the probability that a channel exists between one of these lakes and Lake Tanganyika was long ago suggested. The alti- tude of Tanganyika above the level of the sea is 1,844 ft. according to Burton and Speke, 2,586 ft. according to Livingstone, and 2,711-2 ft. as measured by Lieut. L. V. Cameron of the British navy, in 1874. The largest of these results is not equal to the elevation -of the Albert N'yanza, itself far below the level of the Victoria lake ; so that if we assume as correct the maximum altitude obtained for Lake Tanganyika, it is still impossible that its waters should flow into the Albert N'yanza, unless Baker's measurement of the height of that lake was erroneous. Under the be- lief, however, that an outlet existed, forming such a communication, Livingstone, accompa- nied by Mr. H. M. Stanley, explored the north- ern end of Tanganyika in 1871. Contrary to previous supposition, the Lusize" or Eusizi river, at this extremity of the lake, proved to be an affluent, and the travellers were unable to find any outflow whatever to the north ; ^the other streams of the region also flowed into the lake, none of them out of it. The weight of opinion among European geographers is opposed to the conclusion reached by Living- stone, that the vast lacustrine river system W. of the Tanganyika lake, which he discovered during his final sojourn in Africa, is connected with the basin of the Nile. The Lualaba, which appears to be the principal stream of this vast network, rises directly S. of Lake Tanganyika,