366 



NATURE 



\Feb. I, 1877 



accompanied by a map on the scale of i : 1,000,000, constructed 

 after that of M, Jagor (" Reise in den Philippinen ") and by 

 some views and geological sections. The volcanoes of the Taal 

 district, the Majajai, the Monte Labo, and Sierra Corasi, the 

 Ysarog, Buhi, and Mayon, or Albay, were visited by the author, 

 and are shortly described. Among other interesting observations 

 we notice the very steep slopes (32°) on which lava-floods may 

 flow sometimes without being interrupted for distances of more 

 than 300 feet, observed on the Mayon. The height of this last 

 being 2,374 metres (7,787 feet). Dr. Drasche points out the error 

 in the index of volcanoes, given in the late Mr. Poulett Scrope's 

 work, where the height of the Mayon is given as 3,200 English 

 feet. Another error of the Index is that an active volcano is 

 reported to exist on " the little island Mindoro," whilst on this 

 rather large island (250 square geographical miles) there are no 

 volcanoes at all, neither active nor extinct. 



In a communication to the Vienna Academy on the nature of 

 gas molecules, M. Boltzmann abandons the notion that they be- 

 have like aggregates of material points (the atoms). He considers 

 that in estimating the impact action of the molecules, we may 

 almost regard the whole aggregate, which we denote as an indi- 

 vidual gas molecule, and which may consist of different sub- 

 stances, perhaps even ether atoms, as rigid. It is found that then 

 the ratio of the heat- capacities of the gas must be if, when the 

 gas molecules have ball-form. The ratio of the heat-capacities 

 will be I "4 if the molecules have the form of rigid bodies of rota- 

 tion, but which are not balls ; and 1 3 if they are of any other 

 form of rigid bodies. These numbers at least seem to agree so 

 far with those found experimentally, that one cannot say that 

 experiment furnishes a contradiction of the theory thus modified. 

 It is further shown that the values experimentally got for the 

 heat- capacity, under this view, are in satisfactory agreement with 

 the heat-capacities of solid bodies. Of course the gas molecules 

 cannot be absolutely rigid bodies ; this is already disproved by 

 spectral analysis, but it may be that the vibrations producing gas 

 spectra are merely brief shiverings during the shock of two mole- 

 cules, comparable to the sound perceived on the shock of two 

 ivory balls. 



The current opinion as to the Ural range not bearing any 

 traces of former glaciers, is now contradicted by M. Poliakoff. 

 This explorer, who has had during the last ten years many 

 opportunities of making a close acquaintance with glacial forma- 

 tions in Southern Finland, in the basin of Lake Onego, and on 

 the Valdai plateau, reports that, while the lower parts of the 

 Ural ridge are connected under large alluvial deposits, its upper 

 parts, especially east of the water-parting, exhibit unmistakable 

 morainic deposits with scratched boulders. The rocks bear 

 also, sometimes, true glacial striae running from north-west to 

 south-east, and certainly such striae would be found more nume- 

 rous, were the localities more thoroughly explored than M. 

 Poliakoff could do as he crossed the ridge on his way to the Obi. 

 A lower secondary ridge, the last crossed by the highway before 

 Ekaterinburg, exhibits also many trainees of immense boulders 

 running in parallel directions, such as are found in Finland, 

 Erthonia, and northern Russia. Further east, on the shores of 

 the Obi (near to the mouth of the Irtysh), the lowest parts of the 

 loose deposits, which are roughly stratified sands, contain a good 

 deal of well-polished and striated boulders of glacial origin. 

 These observations make it very desirable that the Ural were 

 thoroughly explored by a geologist well acquainted with glacial 

 formations . 



The Gottingen Academy announces the following subject for 

 prize competition in the physical class till November, 1878 : — 

 The question what special actions (if such there be) breathing in 

 pure oxygen gas of the ordinary density of atmospheric^ air has 

 on the animal organism, has not hitherto been answered by 



researches with sufficient agreement Further researches, there- 

 fore, are desired, both on homoiothermal and, as far as practi- 

 cable, on poikilothermal animals ; in these should be shown, quite 

 specially, along with the phenomena externally observable in the 

 animals, the nature of the change of blood and material (excre- 

 tion of carbonic acid, nature of urine). In the view of certain 

 data, the purity of the oxygen from all foreign matters occurring 

 in its preparation must be carefully looked to, while a mixture of 

 atmospheric nitrogen within narrow limits, hardly to be avoided, 

 would not essentially vitiate the results. In the mathematical 

 class of the same Academy, new researches are desired on the 

 nature of the unpolarised light-ray, calculated to bring the ideas 

 regarding natural light from any source, near to those which 

 theory connects with the different kinds of polarised light. 



We have received the Fourth Report of the New Cross 

 Microscopical and Natural History Society, which, we are glad 

 to see, continues to prosper. It contains an address by the pre- 

 sident, Dr. F. T. Taylor, on "Spontaneous Generation." 



From the Seventh Annual Report of the Wolverhampton Free 

 Library Committee, we are glad to learn that a Naturalists' and 

 Archaeological Department has been established in connection 

 with that institution. 



In 1875 a Bedfordshire Natural History Society was formed, 

 and it has just issued its first Abstract of Proceedings. It has 

 made a very fair beginning both as to numbers and as to the 

 quality of the papers read. We hope it will receive more en- 

 couragement from residents in the county than it appears to have 

 done, and that it will work diligently at local natural history. 

 One of the papers, accompanied by a map, is ' ' On the Botani- 

 cal Division of Bedfordshire," by Mr. W. Hillhouse, F.L.S. 



Among the papers in the Proceedings of the Belfast Natural 

 History and Philosophical Society for 1875-6, is one by Mr. J. 

 J. Murphy on the Glacial Climate and the Polar Ice-cap. Mr. 

 R. Lloyd Patterson has a concluding note on some of the swim- 

 ming birds of Belfast Lough. 



The additions to the Zoological Society's Gardens during the 

 past week include two Vervet Monkeys ( CercopUheeus lalandii) 

 from South Africa, presented by Mr. T. G. Butler ; two Arctic 

 Foxes ( Cams lagopus) from the Arctic Regions, presented by 

 Sir Thomas Erskine, Bart, F.Z.S. ; a Ring-Necked Parrakeet 

 {Palccornis torquata) from India, presented by Miss Smith ; 

 three Silky Marmosets {Midas rosalia) from Brazil, purchased. 



SOCIETIES AND ACADEMIES 



London 



Royal Society, December 21, 1876. — "On the Rotation of 

 the Plane of Polarisation of Light, by Reflection from the Pole 

 of a Magnet," by George Francis Fitzgerald, M.A. Communi- 

 cated by G. Johnstone Stoney, F.R.S. 



At the last meeting of the British Association, the Rev. j. 

 Ker described a delicate and very remarkable experiment, from 

 which it appeared that when plane polarised light is reflected 

 from the polished surface of the end of a powerful magnet, the 

 plane of polarisation is rotated. Mr. Geo. F. Fitzgerald has 

 recentlycommunicatedtothe Royal Society an explanation of this 

 curious phenomenon, of which the following is an abstract : — 



It is known from Faraday's and Verdet's experiments that 

 when plane polarised light is transmitted through transparent 

 diamagnetic or ferro-magnetic media, while under the influence of 

 a powerful magnet, the plane of polarisation will l^e rotated, sO 

 that the plane of polarisation of the emergent beam will differ 

 from that of the incident light. This action is most powerful 

 when the direction of transmission coincides with the direction of 

 the streams of magnetic influence, and in general the rotation is 

 in opposite directions in diamagnetic and in ferro-magnetic media. 

 Now, if we regard the incident light as formed of the two circu- 

 larly polarised beams which are equivalent to it, we learn from 

 Faraday's and Verdet's experiments that one of these beams is 



