June 22, 19 16] 



NATURE 



somewhat purer sugar than was the case in the pre- 

 vious work; the results extend over the range alreadv 

 covered by Prof. Morse and his co-workers, and the 

 two sets of numbers are found to differ slightlv at the 

 lower concentrations. For the ionised substances 

 examined it may be stated that, with the exception of 

 one salt, all those having a molecule made up of a dyad 

 base combined with a dyad acid radicle are associated 

 in aqueous solution. The "dynamic" method of 

 measuring osmotic pressures is developed so as to 

 afford a means of rapidly estimating molecular weights 

 to a considerable degree of accuracv even in ver\- 

 dilute solution.— Prof. E. Wilson and Prof. J. W. 

 Nicholson : The magnetic shielding of large spaces and 

 fts experimental measurement, (i) The magnetic 

 shielding of a large space is a problem wholly different 

 in practice from that of a small space, and in view 

 of important applications the efficiency to which much 

 shielding can be raised is a matter of importance. 

 Considerations of mobility of the apparatus and weight 

 of iron required necessitate the solution of the problem 

 of maximum shielding for a given weight of iron and 

 more than two shells, together with an examination of 

 the limitations of utility of lamination. These problems 

 are discussed in the paper. (2) A field of order as 

 low as 3 X 10-^ has been obtained in a space of radius 

 30 cm. by the use of 1273 kilos (2806 lb.) of high- 

 permeabilit}.- dynamo magnetic steel, and an accurate 

 method designed for the measurement of fields of 

 lower order. (3) The leakage through air spaces in a 

 magnetic shield has been studied. (4) It is now pos- 

 sible to examine the behaviour of iron under prac- 

 tically no magnetic force.— G. I. Taylor : Motion of 

 solids and fluids when the flow is not irrotational. 

 The paper deals with the motion of solids in rotation- 

 ally moving fluids, a problem which has not appar- 

 ently engaged the attention of mathematicians before. 

 The motion of cylindrical solids in rotating fluids is 

 discussed, and it is shown that a solid cylinder of the 

 same density- as the fluid will move through a rotating 

 fluid exactly as if the fluid were not rotating. On 

 the other hand, a solid sphere of the same density as 

 the fluid will be deflected to the right if the fluid is 

 rotating anti-clockwise, and to the left if it is rotating 

 clockwise. This property of rotating fluids is demon- 

 strated experimentally by means of experiments per- 

 formed with a rotating tank full of water. It is 

 shown experimentallv that vortex ring.s move in circles 

 through a rotating fluid. 



Mattiematical Society, June 8. — Sir J. Larmor, presi- 

 dent, in the chair.— Prof. M. J. M. Hill : The classifi- 

 cation of the integrals of a linear partial differential 

 equation of the first order.^Prof. W. H. Yonng : (i) 

 Non-absolutely convergent, not necessarily continuous, 

 integrals. (2) The convergence of Fourier series and 

 of their derived series. — Dr. S. Brodetsky : The general 

 linear differential equation. — A. E. Jollilfe : A note on 

 the series ^a^ sin nB and Sa, ^^s nB, where (a,) is a 

 sequence of positive numbers tending steadily to zero. 

 — -T. C. Lewis : Circles connected with " four Tucker 

 circles."— F. J. \V. Whipple : A symmetrical relation 

 between Legcndre's functions with parameters cosh a 

 and cotho." — H. T. J. Norton: A problem in Diophan- 

 tine approximation^ 



CAMBRIDGE. 



Philosophical Society, May 22. — Prof. Xewall, presi- 

 dent, in the chair. — Dr. Willis : Some considerations 

 on the geographical distribution of species. In some 

 recent papers it has been sought to show that the 

 dispersal of species (so long as no barriers inter\-ene) 

 depends simply upon their age within the country- con- 

 cerned, and is independent of natural selection. A 

 general account was given of the results so far ob- 

 tained by a study of the floras of Ceylon and New 



NO. 2434, VOL. 97] 



' Zealand. — C. P. Dntt : A preliminarj- note on the 

 internal structure of Pityostrobus {Pinites) macro- 

 cephalus from the Lower Eocene. A brief description 

 is given of the general anatomy of two forms of cone 

 from the Lower Eocene of the London basin, attention 

 being drawn to certain unrecorded or characteristic 

 features. The structure of the seeds is described for 

 the first time, and the presence of fossil embr>os is 

 recorded. Pollen grains are found occurring at the 

 apex of a peculiar nucellar column. Evidence is 

 given that the two forms are specifically identical, and 

 are related to an existing species, Pintis excelsa. 



Edinburgh, 

 Royal Society, May 15.— Dr. J. Home, president, in 

 the chair.— Dr. D. Ellis : The Jurassic fossil fungus, 

 Phycomycites Frodinghamii, Ellis. The paper brings 

 forward fresh evidence of the true biological nature 

 of this fossil fungus, found by the author in the 

 Frodingham Ironstone of Lincolnshire. It is the first 

 recorded instance of fossil fungi from Jurassic rocks. 

 The probable reason for its preservation was the 

 absorption within the organism of iron from the sur- 

 rounding water. The members thus became impreg- 

 nated with ferric oxide, as in the case of modern 

 iron-bacteria. The most significant feature is that the 

 fossil threads show the same variations in nature of 

 membrane as in these bacteria. Although no traces 

 were found of the cellular tissues of the animal host 

 in the Frodingham Ironstone, such traces were found 

 in combination with fungal threads in the Dunliath 

 ferruginous limestone. It is interesting to note that 

 this fossil fungus was found in a marine deposit. — 

 Dr. R. A. Honstonn : A possible explanation of the 

 satellites of spectral lines. Many bright lines in the 

 spectra of gases are accompanied by fainter lines 

 loiown as satellites. The usual way of regarding 

 these is to consider them as due to independent elec- 

 trons or degrees of freedom in the molecule. The 

 view presented in this paper and worked out mathe- 

 matically was that thej' might be regarded as due to 

 the same degree of freedom as the main line, being 

 caused merely by the manner in which the vibrations 

 are started or stopped. 



Paris. 

 Academy of Sciences, June 5. — M. Camille Jordan in 

 the chair. — H. Le ChateUer : The devitrification 

 of glass (cristai). Devitrification has hitherto 

 been noticed only in glasses containing lime 

 and calcium monosilicate, CaSiOj separating out. 

 Details are given of a case of devitrification in a lead 

 glass. The separated crystals in this case were found 

 to be tridymite, and this is the first example of a 

 crystallisation of silica in the devitrification of a glass. 

 — A. Chanvean : Dr. Lucien Jacquet and tuberculosis 

 j in the employes in Parisian wine-bars. Important 

 hj-gienic consequences of the new facts obtained in 

 this study. — A. Blondel and J. Rey : The comparison, 

 from the point of view of range, of short light signals 

 produced by a rotating apparatus, by sources of light 

 giving different periods of impression. The conditions 

 of maximum efficacity of the light flux utilised. The 

 e.xperiments described prove that in the utilisation of a 

 source of light for the production of light flashes suc- 

 ceeding each other at fixed intervals, and produced by 

 the rotation of an optical apparatus, it is better that 

 the flashes should be as short as possible. — A. Denjoy : 

 Certain classes of functions of real, variables.— M. 

 Frechet : The equivalence of two fundamental proper- 

 ties of linear ensembles. — G. Hall-Hamilton : Study of 

 the planet Mars at the Flagstaff Observatory, .Arizona. 

 .\ map of the markings on the planet is given. The 

 atmosphere proved to be exceptionally favourable for 



