496 



NATURE 



{March 22, 1888 



Star. 



U Cephei 



S Piscium ... 



Algol 



R Canis Majoris. 



S Cancri ... . 

 5 Librae 



U Coronas ... . 

 U Ophiuchi... 



W Sagittarii 



R Scuti 



R Delphini ... 

 T Vulpeculae 



5 Cephei 



Mercury in conjunction with and o° 2' north 



of Mars. 

 Mars in conjunction with and 2° 35' south 



of the Moon. 

 Mercury at greatest elongation from the 



Sun 28° west. 

 Saturn stationary. 

 Jupiter in conjunction with and 3° 32' south 



of the Moon. 



Mar. 



17 57-9 



18 41-5 

 20 9-5 



20 467 



29 35 S. 

 5 SoS. 



8 4S N., 

 27 50 N, 



... 22 25-0 ... 57 51 N. ... ,, 

 M signifies maximum ; ni minimum. 



Meteor- Showers. 

 R.A. Decl. 



Near y3 Draconis ... 

 ,, ^Draconis .. 



263 

 260 



49 N. 

 63 N. 



March 28. 

 slow. 



Rather 



GEOGRAPHICAL NOTES. 



In a previous number we referred to the return of M. Edouard 

 Dupont, Director of the Brusse's Natural History Museum, from 

 his visit to the Congo for the purpose of scientific exploration. 

 Some of the results of his visit he described the other day to the 

 Belgian Society of Engineers. M. Dupont pointed out that the 

 African interior is drained mainly by four great rivers — the Nile, 

 the Niger, the Zambezi, and the Congo — each of which has to 

 break through the low range that bounds the interior somewhat 

 saucer-shaped tab^e land. The Congo, before making its great 

 final effort, is to some extent dammed back into the reservoir 

 known as Stanley Pool. M. Dupont's journey extended from the 

 mouth of the river to the embouchure of the Kassai. The sub- 

 soil of the Lower Congo he found to be a soft and impure lime- 

 stone covered with sand and clay. The mountainous region 

 begins before arriving at Boma, and may be divided into three 

 sections, according to the composition and aspect of the rocks. 

 There is in the first place granite, gneiss, mica-schist, quartzite, 

 and amphibolic rocks, in strongly inclined beds, and extending 

 from Fetish Rock, below Boma, to the neighbourhood of 

 Isanghila. The river from Vivi rushes in a series of cataracts 

 through a gorge 55 miles long. Then follow schists and sand- 

 stones ; and a little beyond Isanghila, at the great bend of the 

 Congo, appear masses of limestone, very similar to those of the 

 Meuse, and which alternate with the schists for about 35 miles. 

 Then folio vv schists and red sandstones to beyond Manyanga. At 

 Isanghila the banks rise into walls, some 700 feet high, of rough- 

 grained, almost horizontal sandstone. This ends at Stanley Pool, 

 where begins the Upper Congo. There is an immediate change 

 in the strata. Some coherent sandstones show themselves at the 

 base of the new deposits, and are topped by a great mass of soft 

 sandstone, of the whiteness of chalk. M. Dupont traced these 

 new rocks to the mouth of the Kassai, where there was nothing 

 to indicate that they soon came to an end. He believes, on the 

 contrary, that they constitute the subsoil of the greater part of 

 the Upper Congo. M. Dupont is convinced, from his observa- 

 tions on the Congo, that the waters in the interior of Central 

 Africa were at one time accum.ulated in a great lake, of which 

 Stanley Pool is the last remnant. Gradually rising to the height 



of the mountains that bordered the plateau, they at last overtopped 

 them, and, rushing down towards the Atlantic, gradually scooped 

 out the channel now occupied by the Lower Congo. Stanley 

 Pool, he considers, is the final stage of this supposed great 

 internal lake. 



A Brussels telegram announces that Lieut. Van Gele has 

 at last succeeded in tracing the connection between the Mobangi 

 and the Welle, proving that the latter flows into the Congo, and 

 is not the upper course of the Shari, thus solving one of the 

 few remaining hydrographical problems in Africa. 



In Erganzungsheft No. 89 of Petermami s Mitteihmgen, 

 Prof. R. Credner concludes his veiy valuible monograph on 

 " Keliktenseen," — lakes which have remained behind after the 

 departure of the sea from a particular area, as contrasted with 

 continental lakes, which have from their origin been altogether 

 independent of the sea. In the present instalment Prof. Credner 

 deals in detail with the geological evidence, and with the various 

 classes of " Reliktenseen " and the mode of their formation. He 

 divides such lakes into three great classes : (i) such as have been 

 formed through the damming up and isolation of parts of the 

 sea through the elevation of the land above sea-level, as in the 

 case of Lake Pontchartrain and the Kurische Haff ; (2) such as 

 are due to the isolation of basin-formed depths of the ocean-bed 

 as a result of "negative changes in level " — emersion lakes, as 

 Loch Lomond and Lakes Wetter and Wenner ; (3) those caused 

 by the retirement or shrinking of mediterranean seas, as the 

 Caspian and Lake Aral. 



At the last meeting of the Royal Geographical Society, Mr. 

 Douglas W. Freshfield read a paper giving the results of his 

 visit to the Caucasus last summer in company with M. de 

 Dechy, Mr. Freshfield dealt at great length with the orography, 

 the glaciation, geology, and ethnology of the Caucasus, and it 

 is impossible to give an adequate idea of his important paper in 

 a note. We can only refer to one or two important corrections 

 which he made in the prevalent statements about the Caucasus. 

 Some existing misconceptions are due to the fact that the 

 Russian staff map embraces only the lower features, the liigher 

 ranges being unmapped. Mr. Freshfield dealt mainly with the 

 part of the chain between Elbruz and Kazbek — the Central 

 Caucasus. The geological structure of the chain has been re- 

 presented with general accuracy by M. Ernest Favre, a son of 

 the well-known Genevese geologist, who visited it in 1868. 

 The backbone, composed of two or more ridges closely parallel, 

 with many short spurs, is in great part gneiss or granite mixed 

 up with crystalline slates. By what seems a strange freak of 

 Nature, it is, east of Adai Choch, rent over and over again to 

 its base by gorges, the watershed being transferred to a parallel 

 chain of clay slates ("Palaeozoic schists"), which has followed it 

 from the Black Sea. There are clay-slate formations north as 

 well as south of the granite backbone ; but on the north they 

 take the form of rolling downs — of any peaks they ever had 

 they have long been denuded. What the mountain climber 

 looking out from any northern outlier of the granite chain sees 

 is a limestone crest, turning its precipitous face towards the 

 snows, sinking gradually to the low fo^t-hills which fringe the 

 steppe. It is pierced by deep romantic defiles through which 

 the glacier torrents make their escape. South of the Caucasus, 

 parallel to, but much further from the main chain, runs a line of 

 limestone heights, the most conspicuous summits of which are 

 the Quamli, close to the Rion, and the Nakerale range, the 

 limit of theRadsha. At the foot of the latter lie the coal-mines of 

 Khebouli, recently connected with Kutais by a railway. Over the 

 summit plateau spreads one of the noblest beech forests in the 

 world, varied by an undergrowth of azaleas, laurels, and box, such 

 as we try vainly to imitate in our English parks. Parallel chains 

 and longitudinal valleys characterize this portion of the chain. 

 In the most reputable treatises it is stated that there are not 

 50 square miles of glaciers in the Caucasus altogether. Mr. 

 Freshfield shows that such a statement is ludicrously absurd. 

 The glaciers of the main chain are many, and some of them are 

 enormous. Among those .that have the largest basins Mr. 

 Freshfield mentions, between the Djiper Pass and the Mamisson 

 on the south side, the Betsho, the Ushba, the Gvalda, the 

 Thuber, the Zanner, Tetnuld, and Adish, the Sopchetura at the 

 western and at the eastern source of the Rion. On the north 

 side there is a great glacier in every glen ; the Karagam and the 

 Bezingi are the largest ; next come the Dychsu, the Zea, the 

 Adyrsu, and Adylsu, and a host of others lying not only on the 

 main chain, but on its spurs, which are glaciated to an extent of 



