96 



NATURE 



[May 28, 1891 



found a reduction of the temperature below 57° to produce no 

 effect, whereas in Mr. Fenn's experiments the temperature must 

 have been below 40°. — The Secretary also read a letter which 

 Lord Walsingham had received from Sir Arthur Blackwood, 

 the Secretary of the Post Office, in answer to the memorial 

 virhich, on behalf of the Society, had been submitted to the 

 Postmaster-General, asking that small parcels containing scien- 

 tific specimens might be sent to places abroad at the reduced 

 rates of postage applicable to packets oi bond fide trade patterns 

 and samples. The letter intimated that, so far as the English 

 Post Office was concerned, scientific specimens sent by sample 

 post to places abroad would not be stopped in future. 



Mathematical Society, May 14. —Prof. Greenhill, F.R.S., 

 President, in the chair. — The following communications were 

 made : — Relations between the divisors of the first « numbers, 

 by Dr. Glaisher, F. R.S. — Wave motion in a heterogeneous 

 heavy liquid, by Mr. Love, — Disturbance produced by an 

 element of a plane wave of sound or light, by Mr. Basset, 

 F.R. S. — On functions determined from their discontinuities and 

 a certain form of boundary condition, and on a certain Riemann's 

 surface, by Prof. W. Burnside. — Messrs. MacMahon, Larmor, 

 Bryan, and the President took part in the discussions on the 

 papers. 



Cambridge. 



Philosophical Society, May 4. — Prof. G. H. Darwin, 

 President, in the chair. —The following communications were 

 made : — The most general type of electrical waves in dielectric 

 media that is consistent with ascertained laws, by Mr. J. 

 Larmor. — -A mechahical representation of a vibrating electrical 

 system and its radiation, lay Mr. J. Larmor. — The theory of 

 ■discontinuous fluid motion in two dimensions, by Mr. A. E, H. 

 Love. The paper contains an account of a modification of Mr. 

 Michell's method. It is shown that, in all problems where the 

 fixed boundaries consist of parts of straight lines, a figure can 

 be constructed whose conformable representation upon a half 

 plane gives rise to the equation of transformation which contains 

 in itself the solution of the problem. The relation by which 

 the representation is effected can in each problem be determined 

 by known methods. The whole subject is thus reduced to integral 

 ■calculus. Several new cases of the resistance offered by 

 obstacles to the motion of fluids are solved. These include 

 the determination of the mean pressure on a disk with an 

 elevated rim, and of the mean pressure on a pier or other 

 obstruction in a canal of finite breadth, — On thin rotating 

 isotropic disks, by Mr. C. Chree. The subject treated is that 

 ■of the rotation about their axes of thin disks whose section 

 parallel to the plane faces consists of a circle or the area between 

 two concentric circles. The paper aims at providing a solution 

 which is not open to the objections recently urged by Prof. 

 Pearson in Nature against previous solutions. 



Paris, 

 Academy of Sciences, May 19.— M. Duchartre in the 

 chair. — Determination of the constant of aberration ; numerical 

 values deduced from two groups of four stars, by MM. Loewy 

 and Puiseux. — On the transit of Mercury, by M. J. Janssen. 

 It is remarked that a conclusive confirmation of the solar origin 

 of the corona would be obtained if Mercury were photographed 

 when at a short distance from the edge of the sun, and appeared 

 in the negative projected upon a luminous background. — On 

 the physical explanation of fluidity, by M. Boussinesq.— The 

 heat of combustion and formation of some chlorine compounds, 

 by MM. Berthelot and Matignon. The experiments indicate 

 that for each equivalent of hydrogen replaced by chlorine in a 

 series of compounds from 30 to 32 calories is disengaged. Cl^ 

 substituted for H„ thus disengages about 30« calories.— On a 

 double halo with parhelia observed on May 15, 1891, by M. A. 

 Cornu.— On a memoir, by Herr W. von Bezold, relative to the 

 theory of cyclones, by M. Faye. — Remarks on the employment 

 of carbon bisulphide in the treatment of phylloxerous vines, by 

 M. A. F. Marion and G. Gastine.— On the intermediate inte- 

 grals of equations from derived partials of the second order, by 

 M. E. Goursat.— On an elementary method of establishing 

 differential equations of which 8 functions form the integral, 

 by M. F. Caspary.— On a class of complex numbers, by M. 

 Andre Markoff. — Quantitative studies of the chemical action of 

 light; Part iii. influence of dilution, by M. Georges Lemoine. 

 Experiments with mixtures of oxalic acid and ferric chloride 

 taken in equivalent proportions but with different quantities of 



NO. I 126, VOL, 



44] 



water indicate that the chemical action of light upon them in- . 

 creases with the excess of water. The action of heat upon the ; 

 mixtures appears to follow the same laws as that of light. — Cal- 

 culation of the temperatures of fusion and ebullition of normal 

 paraffins, by M. G. Hinrichs. A comparison is given of the 

 observed and calculated melting and boiling points of the 

 normal paraffins. The method of calculation is contained in 

 Comptes rendtis. May 4, 1891.— On the action exercised by 

 alkaline bases on the solubility of alkaline salts, by M. Engel. — 

 On the detection of silica in the presence of iron, by M. Leclere. 

 — On the constitution and heat of formation of bibasic erythrates, 

 by M. de Forcrand. — Thermal data relative to propionic acid 

 and the propionates of potash and soda, by M. G. Massol. Facts 

 are stated which prove that propionic acid, in combining with 

 potash or soda, disengages as much heat as its superior and 

 inferior homologues, acetic and butyric acids. — On the heat of 

 dissolution and the solubility of some organic acids in methyl-, 

 ethyl- and propyl-alcohols, by M. Timofeiew. The results indi- 

 cate that there is a relation between the molecular solubility and 

 heat of dissolution, the variation of molecular solubility carrying 

 with it a variation, in the opposite sense, of the heat of disso- 

 lution. — Action of chlorides of bibasic acids on cyanacetic ethers, 

 by M, P, T. Mullen — On the formation of nitrates in the earth, 

 by M, A, Muntz. — Considerations of abysmal waters, by M. J. 

 Thoulet. — On the genus Royena of the family Ebenacese, by 

 M. Paul Parmentier. — On an inferior Basidiomycete parasite of 

 grapes, by MM. Pierre Viala and G. Boyer. — On a particular 

 appearance of the Cretaceous formation in the Bou-Thaleb group, 

 Algeria, by M. E. Ficheur.— A bed of nephritis found in 

 China, in the Nan Chan mountain-chain, by M. Martin. — 

 Correction to a note on a recently described fossil, by M. 

 Stanislas Meunier. — Discovery of a human skeleton contem- 

 porary with the Quaternary volcanic eruptions of Gravenoire 

 (Puy-de-D6me), by MM. Paul Girod and Paul Gautier, — 

 Chemical and physiological researches on microbic secretions ; 

 transformation and elimination of organic matter by the 

 pyocyanic bacillus, by MM. A. Arnaud and A. Charrin. 



CONTENTS. PACK 



Medical Research at Edinburgh. |By J. George 



Adami 73 



The Chemical and Bacteriological Examination of 



Potable Waters. By P. F. F 74 



Our Book Shelf:— 



Johnstone : "Botany : a Concise Manual for Students 



of Medicine and Science." — C. H. W. 75 



Sim : " Hand-book of the Ferns of Kaffraria," — ^J. G. 



Baker, F.R.S 75 



Deakin : " Rider Papers on Euclid " 76 



Lehmann : " Die Krystallanalyse " 76 



Letters to the Editor : — 



The University of London. — Prof. E. Ray Lan- 

 kester, F.R.S. ; Prof, William Ramsay, 



F.R.S. ; Dr. Irving 76 



Quaternions and the " Ausdehnungslehre." — Prof. J. 



Willard Gibbs 79 



The Flying to Pieces of a Whirling Ring.— G. Chree . 82 

 A Comet observed from Sunrise to Noon. — Captain 



Wm. EUacott 82 



Graphic Daily Record of the Magnetic Declination or 

 Variation of the Compass at Washington. — Richard- 

 son Clooer 82 



The Alpine Flora.— J. Lovel 83 



Magnetic Anomalies in Russia. — General A. de 



Tillo 83 



The Rejuvenescence of Crystals. By Prof. John W. 



Judd, F.R.S 83 



British Institute of Preventive Medicine 86 



Notes 86 



Our Astronomical Column :— 



The Draper Catalogue of Stellar Spectra 89 



Solar Observations from January to March 1891 ... 90 



The Constant of Aberration 90 



Animal Life on a Coral Reef. By Dr. S. J. Hickson 90 



Washington Magnetic Observations, 1886 91 



University and Educational Intelligence 91 



Scientific Serials gi 



Societies and Academies 92 



