June i6, 1904] 



NATURE 



167 



The experiments of the author were devoted to forcing 

 water through woody stems, but references to the work of 

 earlier investigators are not given. 



Mathematical Society, June g. — Prof. H. Lamb, presi- 

 dent, in the chair. — The following papers were communi- 

 cated : — Note on the application of Poisson's formula to 

 discontinuous disturbances : Lord Rayleigrh. Poisson's 

 solution of the equation 



32* „ „ 

 4 = "-^^ 

 has the form 



where 0(, and 0„ denote initial values of ij> and d(p/d/ 

 on a sphere of radius at, and the integration refers to 

 angular space about the centre of the sphere. When the 

 initial disturbance is continuous at the surface bounding 

 the initially disturbed portion of the medium, the solution 

 mav be written in the form 



^i,IJi 



<p = 



/•Po + t'o + r 



.S'Po 



7°) " 



It is pointed out in the paper that, when there is discon- 

 tinuity, the subject of integration in the latter form becomes 

 infinite, and it is shown by an example how the integral 

 may be interpreted so as to yield the correct result. — Wave 

 fronts considered as the characteristics of partial differential 

 equations ; T. H. Havelock. It is shown that a wave 

 front can be defined as a surface satisfying the principal 

 equation of the characteristics of the equation of wave 

 motion, and that, owing to the linearity of the latter equa- 

 tion, there is no necessity for the continuity of the first 

 differential coefficients of the function expressing the dis- 

 turbance, provided the function itself is continuous. The 

 theory is extended to systems of partial differential equations, 

 and, in particular, to the equations of propagation of electric 

 waves. .An invariantive property of characteristics is 

 proved, and is applied to the theory of wave fronts and rays 

 in moving media. — Illustrations of perpetuants : J. H. 

 Grace. The quantic of infinite order being equivalent to 

 a power series, the perpetuants are expressed as the results 

 of performing certain operations of differentiation upon 

 analytic functions represented by such series. It is shown 

 that certain ones of the known analytic functions, such as 

 the exponential function and the Weierstrassian sigma 

 function, are determined by the vanishing of the simpler 

 perpetuants. — Types of covariants of any degree in the 

 coefficients of each of any number of binary quantics : P. W. 

 Wood. A method is given for determining the type forms 

 (if the complete system mod {ab}*-". The method consists 

 in carrying out systematically a process indicated by Jordan, 

 and previously applied to perpetuants by Grace. — Some ex- 

 pansions for the periods of the Jacobian elliptic functions : 

 H. Bateman. 



DUBLI.V. 



Royal Dublin Society, May 17.— Prof. J. A. McClelland 

 in the chair. — Mr. J. H. Pollok read a paper on the extrac- 

 tion of glucina from beryl by fusion with caustic soda, 

 solution in hydrochloric acid and saturation with hydrogen 

 chloride to precipitate the alumina, the glucina and iron 

 being afterwards separated by ammonium carbonate and 

 sulphide. Analyses of carbonates, sulphates, and chlorides 

 were also given that differed somewhat from theory. — Mr. 

 F. E. Hackett read a paper on the n-rays. Some estim- 

 ations of the magnitude of the subjective effects in the dark- 

 adapted eye are given in this paper. It was found that 

 bodies under strain produced an effect on a phosphorescent 

 screen which could not be assigned to eye effects or the 

 emission of heat. 



Paris. 



Academy of Sciences, June 6. — M. Mascart in the chair. — 

 On the parallax of the sun : Bouquet de la Grye. An 

 account of the mode of working up the data from the 

 photographic plates obtained in the French expedition for 

 the observation of the transit of Venus in 1882. — On the 



photography of the superposed layers which constitute the 

 solar atmosphere : H. Deslandres. A discussion of the 

 work done with the large refractor at the Yerkes Observ- 

 atory in relation to earlier results, together with some 

 suggestions as to future work. — The accidental production 

 of an intraliberian generating layer in the roots of Mono- 

 cotyledons : Gaston Bonnier. A wound may provoke in 

 the roots of certain Monocotyledons the commencement of 

 secondary formations organised in the same manner as in 

 a root of a Dicotyledon. — The physiological action of the 

 emanation of radium : Ch. Bouchard, P. Curie, and 

 V. Balthazard. The introduction of the radium eman- 

 ations into the lungs of animals gives rise to toxic effects, 

 the dominant lesion observed on post mortem examination 

 being an intense pulmonary congestion. The tissues of the 

 animals which have died under the action of the radiations 

 are radio-active. — The radium emanation, exradio, its 

 properties and changes : Sir William Ramsay. The eman- 

 ation which escapes from radium bromide possesses the 

 properties of a gas ; it obeys Boyle's law, can be con- 

 densed at low temperature, and possesses an appreciable 

 vapour pressure at the temperature of liquid air. The 

 quantities available were extremely minute, about 00254 

 cubic millimetre, but this was found sufficient to prove the 

 relation between volume and pressure, and also to obtain 

 the spectrum. The gas is strongly luminous, but this grows 

 weaker with time, and at the end of a month disappears. 

 The gas appears to belong to the argon group, and has a 

 density of about 80. If the molecule is monoatomic, the 

 atomic weight would be 160, from which it would follow 

 that one atom of the emanation is produced from one atom 

 of radiuiTli — The action exercised by the n-rays upon the 

 intensity of the light emitted by a small electric spark, and 

 upon some other feeble sources of light : R. Blondlot. 

 A discussion of the views of M. Jean Becquerel as to the 

 action of the n-rays upon the luminosity of a calcium 

 sulphide screen, and an extension to the cases of a small 

 electric spark and of a piece of platinum foil at a dull red 

 heat. — On the emission of the n-rays and the n,-rays : E. 

 Bichat. — On the emission of the n-rays and n,-rays by 

 crystallised bodies : E. Bichat. — On the fifth scientific cam- 

 paign of the Princesse Alice : Prince Albert of Monaco. — On 

 e.xpressions formed of superposed radicals : Paul' Wierns- 

 bergBr. — On the movements of solids with spherical 

 trajectories : Jules Andrade. — On a variant of the universal 

 joint : L. Lecornu. — On the critical velocity of directable 

 balloons : Ch. Rcnard. It is shown that a balloon of the 

 Santos-Dumont type must become ungovernable when the 

 velocity approaches a certain critical value. — On the 

 kathode rays : P. Villard. It is shown that the properties 

 of the magneto-kathodic rays are inverse to those of the 

 Hittorf rays; an electric field acts on the first like a mag- 

 netic field does on the second. — On a method of measuring 

 coefficients of self-induction : M. Iliovici. — On the pheno- 

 mena which accompany the contemplation in a dark room 

 of feebly luminous surfaces illuminated by special kinds of 

 light. The case of spots of phosphorescent sulphide ; the 

 effects of anesthetics : F. P. Le Roux. — On the anaesthesia 

 of metals : Jean Becquerel. Aluminium and copper lose 

 their transparency to the n-rays when the surface which 

 receives the radiation is submitted to the action of an 

 anaesthetic ; quartz appears to possess the same property. 

 Glass, wood, and cardboard, on the other hand, always allow 

 the radiation to pass through. — A method for the continuous 

 registration of the state of ionisation of a gas : Ch. 

 Nordmann. — The influence of the frequency in electrolysis 

 by alternating currents : Andr^ Brochet and Joseph Petit. 

 The electrolytic properties of alternating currents appear to 

 be altogether different from those of continuous currents. 

 The results obtained depend on the frequency of the 

 alternations. — On the use of the n-rays in chemistry : 

 Albert Colson. — On the reduction of o-nitrobenzyl alcohol. 

 General remarks on the formation of indazyl derivatives : 

 P. Freundler. The principal reduction products of 

 o-nitrobenzyl alcohol are indazyl-o-benzyl alcohol, indazyl-o- 

 benzoic acid, and anthranilic acid. — A new method for the 

 preparation of anilides : F. Bodroux. The alkyl- 

 magnesium compound is treated with an amine, and to the 

 product an alkyl ester is added. From this, hydrochloric 

 acid gives the anilide in a nearly theoretical yield. Details 



NO. 1807, VOL. 70] 



