Nov. II, iSSo] 



NA TURE 



45 



direction of their Professor of Natiual History, M. Slielting, 

 made an excursion in the Ala taou Mountains. Numerous 

 measiu'ements of heights were made during the journey, good 

 zoological, botanical, and geological collections, for the Museum 

 of the College, -were made, and a detailed diary of the excursion 

 was kept by the scholars. The students of the Tashkent 

 Normal School, as well as the pupils of the College of Verny, 

 have also made scientific journeys for the exploration of the 

 neighbourhood, and we learn that the College of Orenburg lias 

 requested tickets at reduced rates from the railway company for 

 undertaking next summer a series of explorations in that little 

 known but very interesting province. We cannot but «ish that 

 the colleges and schools of Western Europe would follow these 

 examples ; what an excellent training in natural science might 

 thus be given, and what a mass of valuable information might 

 be collected. 



The members of the scientific expedition which was sent 

 out by the St. Petersburg and Moscow Societies of Naturalists 

 for the exploration of the White .Sea and of the Murmanian 

 coast of the Arctic Ocean, and v\hich con-isted of Professors 

 Wagner, Bogdanoff, Tsenkovsky, and eight students of the 

 University, have returned after having done some very successful 

 work ; they bring home very rich zoological and geological col- 

 lections. Professors Wagner and Tsenkovsky stayed throughout 

 the summer at the Solovetsky Islands ; M. Lavroff in Kanda- 

 laksha Bay ; Prof. Bogdanoff travelled along the \;hole coast 

 to Vadso ; MM. Koudravtreff and Pleske, geologists, have 

 travelled from Kandalaksha to Kola ; others have explored the 

 flora and the fauna of the ocean ; Prof. Bogdanoff has also 

 studied the fishing. 



Baron A. von Hugel is now engaged in writing a work 

 upon Fiji, where he travelled and spent some time, making 

 extremely extensive and complete anthropological collections. 

 The work will be more particularly an ethnological one, and 

 most of the weapons, fabrics, and other ethnographic articles 

 are being figured to accompany the text. The crania collected 

 by Baron von Hugel have already been acquired liy the Koyal 

 College of Surgeons, and exhaustively described by Prof. 

 Flower. 



We notice the appearance of an important work published by 

 the Russian Geographical and Economical Societies in the first 

 volume of a "Collection of Materials for the Knowledge of the 

 Rus,-ian Commune." It contains detailed descriptions of the 

 communes of the Governments Ryazan, by M. .Semenoff, pre- 

 sident of the Russian Geographical Society, MM. Litochenko, 

 Zlatovratsky, Mme. Yakouchkin, &c. ; a very complete biblio- 

 gi-aphical index of the literature concerning the communes of 

 Russia and of Western Europe. 



A TELEGitAM has been received at St. Petersburg from Col. 

 Prejevalsky, dated from Urga, the 1st inst., stating that during 

 the spring and summer of this year he surveyed a part of the 

 basin of the Upper Hoang-ho and the Lake Koko Nor. He 

 also passed through Alashan, in the centre of the Gobi desert, to 

 Urga. Col. Prejevalsky states that during the expedition he 

 traversed a distance of 7200 versts, and that he has succeeded in 

 obtaining valuable scientific results. 



The death is announced, on his passage home from West 

 Africa, of Count de Semelle, who has been recently exploring on 

 the Lower Niger. 



The new Bulletin of the Societe Khediviale de Ge'ographie 

 contains a paper by General Purdy- Pacha on the country between 

 Dara and Henfiah El Nabass, together with a map of that 

 portion of Darfur, and another on Medina twenty years ago, 

 by Col. Mohamed Sadik-Bey, illustrated by two engravings. 



The Church Missionary Society have received news that the 

 Rev. P. O'Flaherty, their new agent in Uganda, and Mr. C. 

 Stokes, with the Wagauda chiefs and a large caravan, started 

 from Saadaui for the interior on August 9, but in little more 

 than three weeks Mr. O'Flaherty was taken ill at Kidete, and 

 will be unable to proceed to the Victoria Nyanza at present. 



The same Society have also received letters from various 

 members of the Nyanza mission, giving a much more favourable 

 report of their position in Uganda than had reached England 

 some time back. Rev. G. Litchfield had in consequence of ill- 

 health made an attempt to push northwards to Lado, in order to 

 consult Dr. Emin Effendi. In this he unfo'tunately failed, 

 being stopped by Kabba Rega, the king of Unporo, who has 



seized M'ruli and other posts vacated by the Egyptians since 

 Col. Gordon's departure. Mr. Litchfield accordingly returned 

 to Rubaga, and, crossing the lake, proceeded to Upui, hoping 

 eventually to get to Upwapwa, where Dr. Baxter is stationed. 



Messrs. Cameron and Pigott, of the China Inland Mission, 

 have made a journey of eight months through a great part of 

 Manchuria and a portion of Mongolia. From the treaty port of 

 Newchwang Mr. Pigott went on to Moukden, while Mr. Cameron 

 proceeded along the coast in an easterly direction by the borders 

 of Corea, and then northwards to Moukden. They next journeyed 

 through part of Mongolia into Kirin, which at first they found 

 fertile and well-wooded, but afterwards the country became wild, 

 poor, and sparsely populated. The city of Kirin was reached 

 by a long steep descent through fine scenery. Fine teams of 

 oxen were here met \\ith, comparing favourably with some of 

 our best breeds. After spending a few days at Kirin the two 

 missionaries returned overland to Peking, passing the Great 

 Wall at Shan-hai-kwan or Ling-yii-hsien. 



Messrs. Riley and Clarke, of the same Society's station 

 at Chungking, have recently paid a visit to some Lolo villages 

 in Southern Szechuen. These mountaineers for the most part 

 live in inaccessible fastnesses beyond the reach of the Chinese 

 authorities, and are not confined to Szechuen and Yiinnan, but 

 under the designations of Laos and sundry other names are 

 found throughout the extensive regions of Annam, Siam, and 

 Burmah. Flardly anything is yet known of the Chinese Lolos 

 and their manners and customs, but before long the agents of 

 the China Inland Mission in the south-west will, it may be 

 hoped, find means to collect information regarding them. 



ON A DISTURBING INFINITY IN LORD 

 RAVLEIGH'S SOLUTION FOR WAVES IN 

 A PLANE VORTEX STRATUM^ 



T ORD RAYLEIGH'S solution involves a formula equivalent 



dy" 



df 





Where v denotes the maximum value of the ^-compotient of 

 velocity ; 



m ,, a constant such that — is the wave-length ; 

 m 

 ,, T ,, the translational velocity of the vortex- 

 stratum when undisturbed, which Is in the .^-direction, and is a 

 function of jj* ; 



„ n ,, the vibrational speed, or a constant such that 



— is the period. 



Now a vortex stratum is stable, if on one side it is bounded 



by a fixed plane, and if the vorticity (or value of --^) diminishes 



as we travel (ideally) from this plane, except in places (if any) 

 where it is constant. 

 To fulfil this condition, suppose a fixed bounding plane to 



contain x and be perpendicular to oy ; and let -^— have its 



greatest value when y — 0, and decrease continuously, or by one 

 or more abrupt changes, from this value, to zero sX y = a and 

 for all greater values of ^. 



It is easily proved that the wave-velocity, whatever be the 

 wave-length, is intermediate between the greatest and least 

 values of T. Hence for a certain value of y between o and a, 

 the translational velocity is equal to the wave velocity, or 

 T — —. Hence for this value of y the second term within the 



bracket in Lord Rayleigh's formula is infinite unless, for the 



d^ T 

 same value of j, —-r vanishes. 

 d y^ 

 We evade entirely the consideration of this infinity if we take 



only the case of a layer of constant vorticity [—— = constant 



from !■ = otoy = a), as for this case the formula is simply 



■ By Sir William Thomson. British Association, Swansea, Section A. 



