520 



NATURE 



[September 20, 1900 



the proper mathematical formulation of these sundry con- 

 ditions so as to obtain a system of equations which can be 

 readily solved. The paper is illustrated by diagrams which put 

 the problems discussed in a clear light. — " Ueber systeme von 

 differentialgleichungen dessen vierfach periodische functionen 

 geniige leisten," by M. Krause, was presented at the Chicago 

 (April) meeting of the present year. References are given to 

 Ilermite (" Sur quelques applications de la theorie des fonctions 

 elliptiques," 1885), and to a paper by Picard {Comp'es rendus, 

 Band 89), and 10 previous work by the author. — E. B. van 

 Vleck follows with a paper on linear criteria for the determination 

 of the radius of convergence of a power series. Its object is to 

 establish criteria for the convergence of a power series when the 

 («+i)th coefficient A„ is connected with the preceding co- 

 efficients by a linear relation which tends to take a limiting form 

 as n increases indefinitely. The criteria include Cauchy's ratio- 

 test as a special case, and may be looked upon as an extension 

 of the test, and are applicable in cases in which the simple ratio- 

 test fails. The paper closes with two theorems which are an 

 extension for the case of two variables, criteria for the converg- 

 ence of power series in such a case are stated to be very rare. — On 

 the existence of the Green's function for the most general simply 

 connected plane region, by W. F. Osgood. — A short but suggestive 

 note — " D " lines on quadrics, by A. Pell. These lines, so 

 named by Cosserat, were originally considered by Darboux. 

 They are the lines drawn upon a surface in such a way that the 

 osculating sphere at every point is tangent to the surface at that 

 point. In addition to the above, the lines have been studied by 

 Enneper and Ribaucour (for surfaces in general). In the present 

 paper the author appliee the theory 01 elliptic functions to the 

 integration of Darboux's differential equation, and obtains an 

 idea of the appearance of the lines and also some of their 

 properties. — Starting from an article, by Prof. F. Morley, in the 

 previous number of the Transactions, F. H. Loud gives sundry 

 metric theorems concerning n lines in a plane. By giving a 

 different interpretation to formuke got by Prof. Morley, Mr. 

 Loud obtains a new series of theorems and other results of some 

 interest. — An application of group theory to hydrodynamics, by 

 E. J. Wilczynski. It was observed by Sophus Lie that the 

 stationary motion of a fluid can serve as a perfect picture of a 

 one-parameter group in three variables. Apparently this fact 

 has not been utilised for the purposes of hydrodynamics. This 

 f)aper does this. Amongst other advantages, the treatment, 

 from the new standpoint, leads to special cases of exceptional 

 interest and importance, which otherwise appear to be difficult 

 and unpromising.— Dr. L E. Dickson, following up work 

 recently published in the Proceedings of the London Mathe- 

 matical Society (vol. xxxi. pp. 30, 351), contributes an article 

 on the determination of an abstract simple group of order 

 2'''3'*'5'7, holohedrically isomorphic with a certain orthogonal 

 group and with a certain hyperabelian group (contributed to the 

 Chicago [April] meeting of the society). 



In Vne Journal of the Royal Microscopical Society for August, 

 Mr. E. M. Nelson has one of his useful technical articles on the 

 " lag " in microscopic vision, as well as a historical account of the 

 improvements in the structure of the microscope introduced by the 

 firm of Ross. Mr. E. B. Stringer describes a new form of fine 

 adjustment. Miss A. Lorrain Smith gives a description of 

 some new microscopic fungi, including a new species of Ento- 

 mophthora, not parasitic, but saprophytic on dead animal tissues. 

 There is, in addition, the usual summary of current researches 

 relating to zoology, botany and microscopy. 



In \.\\Q Journal of Botany for August, Messrs. W. and G. S. 

 West have a second instalment of their notes on freshwater 

 algae, in which some new species and varieties are described. 

 The remaining papers are descriptive or geographical. 



SOCIETIES AND ACADEMIES. 



Paris. 

 Academy of Sciences, September 10.— M. Maurice Levy 

 in the chair. — Occultation of Saturn by the moon on September 

 3 observed at the Observatory of Lyons, by MM. J. Guillaume, 

 G. Le Cadet and M. Luizet. — On differential systems with a 

 general uniform integral, by M. Paul Painleve. Four types of 

 systems are examined, problems in mechanics such as the- move- 

 ment of a heavy body fixed by a point, the inversion of total 

 differentials, the case where the general integral of a differential 

 system does not admit of transcendental singularities, and the 



NO. 16 I 2, VOL. 62 1 



study of the integrals of a differential system in a real field. — On 

 the liquefaction of air by expansion with production of external 

 work, by M. Georges Claude. — On the dielectric cohesion of 

 gases and vapours, by M. E. Bouty. The experiments previously 

 described upon the relation existing between the distance at which 

 insulation breaks down and the pressure of the gas have been 

 extended to vapours of liquids. Results of measurements for 

 water, and eleven organic liquids, are given in the present paper. 

 — On the modification of the electrical and organic properties of 

 cables under the prolonged action of currents, by M. Georges- 

 Rheins. When a cable is submitted to the action of an alter- 

 nating current it preserves its electrical and organic properties- 

 intact. With a continuous current in one direction the cable 

 gradually loses its electrical properties, this effect being pro- 

 duced by the slow penetration of the copper from the wire into- 

 the sheath. The effect is similar with both gutta and paper 

 coatings. — New researches on the absorptive power of haemo- 

 globin for oxygen and carbonic acid, by M. L. G. de Saint- 

 Martin. As the result of numerous experiments quoted, the 

 author is of opinion that, contrary to the views generally held, 

 it is impossible, especially in pathological cases, to estimate 

 haemoglobin by means of the absorbing power of the 

 blood. — On the nitrocelluloses, by M. Leo Vignon. Both the 

 nitrocelluloses and the nitro-oxycelluloses energetically reduce 

 Fehling's solution, their reducing power being apparently inde- 

 pendent of the degree of nitration. The reducing powers of the 

 nitration products of cellulose and oxyceliulose are of the same 

 order, about one-fifth that of inverted sugar. — On the wood of 

 the Conifers of peat bogs, by M. L. Geneau de Lamarliere. In 

 the wood of Conifers taken from a peat bog, the intercellular 

 layer formed of lignin and pectic comjjounds is intact, whilst 

 the internal portion has been strongly attacked by microbial 

 action. The lignin and cellulose have disappeared, an amor- 

 phous substance remaining behind which is soluble in potasli 

 after the action of chlorine. The material resembles callose. — 

 Influence of a dry or moist medium upon the structure of plants, 

 by M. Eberhardt. Compared with normal air, the effect of dry 

 air is to increase the thickness of the epidermal cuticle and the 

 number of stomata, to make the cork layer form earlier, to 

 increase the production of ligneous tissue, and to cause an 

 increase in the amount of pallisade tissue in the leaf. 



CONTENTS. PAGE 



A Magnetic Theory of the Universe. By Prof. R. 



Meldola, F.R.S 493 



Our Book Shelf: — 



Horovitz : " Untersuchungen iiber Pliilons und 



Platons Lehre von der Weltschopfung." — H. W. B. 494 

 McAlpine : " Fungus Diseases of Citrus Trees in 



Australia, and their Treatment " 494 



".Missouri Botanical Garden. Eleventh Annual 



Report" 495 



Letters to the Editor: — 



Atmospheric Electricity and Dew-ponds.— Arthur 



Marshall 495 



Huxley and his Work.— C. Simmonds 495 



A Large Tasmanian Crab. {Illustrated.) — Alex. 



Morton 496 



Large PufT Balls.— W. A. Sanford ....... 496 



"A Tour through Great Britain in 1727." — S. L. 



Petty 496 



Prof. Henry Sidgwick 496 



Prof. James Edward Keeler 497 



Notes 497 



Our Astronomical Column:— 



Ephemeris for Observations of Eros 501 



Swift's Comet (1892 I.) 501 



Ths Bradford Meetmg of the British Association :— 

 Section D.— Zoology. — Opening Address by Dr. 



Ramsay H. Traquair, F.R.S 502 



Section F. — Economic Science and Statistics. — 

 Opening Address by Major P. G. Craigie, 



President of the Section 509 



Section H. — Anthropology. — Opening Address by 

 Prof. John Rhys, President of the Section . . 513 

 The International Congress of Applied Chemistry 519 



University and Educational Intelligence 519 



Scientific Serials 519 



Societies and Academies 520 



