June 8, 1882] 



NA TURE 



139 



sounding motion, ai d the dependence of the qualities of the tone 

 on the nature of the motion. A rar idly-rotated >haft has an 

 adjustable eccentiic with jointed rod, which at each rotation 

 pulls a large drum-skin to and fro. A bell-mouth strengthens 

 and concentrates the tones. The velocity of rotation determines 

 the pitch ; the eccentricity the strength of the tones. The 

 phonomotor acts on the opposite principle, rotatory motion being 

 got from vibration. In the elcctromagnctophone a piece of sheet- 

 iron under an electn magnet has a point dipping in mercury ; a 

 current passing through the coils and the point becomes readily 

 intermittent, and the membrane sounds. The electromagnetic 

 membrane-siren is similar, but a solid sliding contact takes the 

 place of the mercury, and a driving-wheel gives rapid interrup- 

 tion. Again, a tuning-fork is supported so as to be capable of 

 rotation before a resonance-case. According to position it gives 

 a strong resonance or a weak interference tone, the latter slightly 

 higher. On rotating, the former becomes lower, the latter 

 higher, and the dissonance ever greater. A resonance-inter- 

 Jerence-pipe is formed by connecting a caoutchouc tube with the 

 nodes of an open pipe. If the tube be shortened by pressure 

 at different parts, the tone of the pipe is raised or lowered through 

 resonance-interference, is extinguished, or lets only the first over- 

 tone be heard. These instruments are n-.ade by G. F. Weigle, 

 in Stuttgart. 



Continuing his researches on "adsorption," or condensation 

 of gases on surfaces of solids, Herr Kayser (U'icJ. Ann. No. 4) 

 has studied the influence of the adsorbing material. The pres- 

 sure was determined, which occuned in the glass vessel when 

 given volumes of gas had been in contact with the solid mate- 

 rial. The gases were carbonic acid, sulphurous acid, and 

 ammonia, and these were adsorbed in the empty glass vessel, by 

 coarse glass powder, and by turnings of brass and wrought iron. 

 'Ihe metal-turnings were quite clean and unoxidised, and before 

 each experiment they were heated in vacuo to about 300°, to 

 remove gas. It was found that pressure was greatest, and so 

 adsorption least, in the empty vessel. The order of increasing 

 ac' sorption was, in general : empty vessel, iron, brass, and glass 

 powder. By the empty vessel, S0 2 was least condensed, CO s 

 and NH a about equally. Also, on the metallic surfaces, S0 2 

 always gave greater pressure than NH 3 ; between CO s and S0 2 

 there was hardly any difference. By the glass surfaces, on the 

 other hand, CO„ was comparatively little condensed, NH 3 con- 

 siderably, and S0 2 to a large extent. 



The behaviour of mercury when polarised in contact with 

 dilute sulphuric acid (as in Lippmann's well-known experiments), 

 and with other acids and salt solutions, has been studied by Herr 

 Konig at the instance of Prof. Hehnholtz ( Wied. Ann., No. 5). 

 The surface-tension, it is shown, reaches a maximum at a mean 

 state of polarisation different for different liquids ; the values 

 diminishing on either side, as one removes from this, and both 

 w ith positive and negative charges. Prof. Helmholtz offers some 

 comments by way of theory on the phenomena. 



From experiments at WiirzLurg (Wied. Ann., No. 5), Mr. 

 William Hallock infers the correctness of the view that the 

 changes of electromotive force of the Smee element are due to 

 action of polarisation. The electromotive force of polarisation 

 is by no means independent (he affirms) of the nature of the 

 electrodes, and it considerably exceeds that necessary for visible 

 decomposition. The polarisation cannot be calculated from the 

 heat phenomena. 



To find whether the two coefficients used in equations of 

 motion of incompressible liquids— one of viscosity, the other of 

 variable adherence of the liquid to the walls — are independent of 

 velocity, M. Elie [Journ. de Phys., May) rotates a solid sphere 

 within another filled with liquid, and hung bifilarly. The smaller 

 sphere (0-04 m. diameter) is supported by a metallic wire passing 

 through an aperture in the larger (o'i2 m.) between the suspend- 

 ing wires to the vertical axis of an electric rotatory apparatus. 

 During rotation (2 to 10 turns in a second) the hollow sphere is 

 di-placed to an amount indicated by a reflected light spot, and 

 stops when the moment of the bifilar suspension balances that 

 due to friction. In all the experiments w ith water, the reactions 

 due to friction were found to increa-e more rapidly than the 

 velocity; the ratio increased a third when the velocity was 

 doubled ; hence it appears that the viscosity or adherence, or 

 both together, increase with the velocity. 



The name of rhtolystr has been given by Prof. Wartmann to 

 an apparatus (described in the Archives des Sciences for May) 



whereby the intensity of a derived electric current may be rapidly 

 varied from zero to a maximum, and which indicates exactly the 

 relation of those variations. A graduated metallic ring round a 

 tripod-supported column encloses a thick disc of glass or ebonite, 

 resting on the six radii of the ring. In the upper surface of the 

 di-c is a circular trough of mercury receiving two copper elec- 

 trodes at the bottom, at a semicircle of interval. A cross-bar 

 on the top of the column, on which it turns as axis, acts as a 

 movable Wheatstone-bridge ; it has two terminal verniers, and 

 two screws dipping in the mercury ; these latter are insulated, 

 but communicate, through central binding screws, with a mirror 

 galvanometer. The intensity of the derived current varies 

 according as the bridge is displaced. 



GEOGRAPHICAL NOTES 

 The last work by Dr. E. Regel, on the Flora of Central 

 Asia, which has recently appeared in the " Acta Horti Petro- 

 pilitani" (vol. vii.), gives to Prof. Rehring, of Berlin, the 

 opportunity of discussing the relations between the present flora 

 and fauna of the North-eastern Asiatic Steppes, and the Post- 

 glacial flora and fauna of Middle Europe. Prof. Regel, on the 

 ground of his researches in Asia, arrived at the conclusion that 

 out of the species which inhabited Central Asia during post- 

 glacial times, very few have migrated towards north-western 

 A-ia and to Europe, aud that the species now inhabiting this 

 part of A-ia have probably immigrated from Europe. The same 

 was the conclusion arrived at several years ago by Dr. Rehring, 

 when he and Dr. Liebe discovered in the Diluvium of Germany 

 (at Wes'tegeln and at Gera), a steppe-fauna much akin to the 

 West Siberian (Dipus jaculus, Arctomys bobac, Spermophilus 

 altaicus, Lcgomys pusillus, Equus laballus, &c), which facts led 

 him t ) the inference that in post-glacial times middle Germany 

 enjoyed a steppe vegetation and climate. The same steppe 

 fauna has since been discovered at many other places in Ger- 

 many, so that it may be said that the German diluvium encloses 

 an unmistakable steppe fauna. Dr. Rehring discovers in Dr. 

 Regel's work new proofs in favour of his theory of migration of 

 the diluvial fauna from Europe to Asia, in opposition to the 

 theory of the late Dr. Brandt, who considered North-western 

 Asia as the true fatherland of the European diluvial fauna. 

 We may observe that Dr. Rehring's theory would imply the 

 migration of the German steppe fauna, not only to North-western 

 Siberia, but also to Eastern Sib-ria, during the post-glacial 

 period, which would involve several important difficulties. We 

 believe that a true theory of the migrations of post-glacial faunas 

 can be established only by taking into account the history of the 

 glacial period in Asia, which history has never investigated. 



Discussing the character of the Glacial period on the Cau- 

 casus, M. Moushketoff points out (Izicstia, vol. xviii. fasc. 2), 

 those features which are common to the former glaciers of the 

 Caucasus, and those of the Zerafshan in Central Asia. He 

 observes the present comparatively small extent of glaciers and 

 snow-fields in both countries. The area now covered with per- 

 petual sno-.v on the Caucasus is very small (250 square kilo- 

 metres) compared with the extent of the same regions in the Alps 

 (more than. 3000 square kilometres). The same relations — M. 

 Moushketoff says — must have existed to some extent between both 

 countries during the Glacial period, because of the greater dry- 

 ness of climate on the Caucasus, and still more in Central Asia, 

 in comparison with Western Europe. He concludes, in accord- 

 ance with M. Abich and many others, that the ancient glaciers 

 of the Caucasus had a far greater extension than the present ones 

 (for instance, those of the Elbrouz reached, at least, down to 

 5200 feet, and the Baskan glacier united into one single mass all 

 the present small glaciers which do not now descend lower than 

 6603 to 8600 feet). Nevertheless the glaciation was not so general 

 as in Western Europe. This conclusion only must be provisional, 

 the traces of the Glacial period having not yet been the subject 

 of a thorough exploration, either on Caucasus or in Turkestan, 

 whilst-the obliteration of these traces has been far more complete 

 iu both these countries than in Europe. Taken in its « ide.st 

 sense, the supposition that the glaciation has been less intense in 

 Middle Asia than in Europe seems very probable, and has been 

 arrived at also by other explorers of Turkestan and Siberia. 



Besides the Annual Address of the President, Lord Aberdare, 

 reviewing the geographical progress of the year, the June number 

 of the Proceedings of the Royal Geographical Society contains 

 Mr. O'Donovan's paper on Merv; M. de Gorloff's account of 



