November 24, 192 1] 



NATURE 



421 



Societies and Academies. 



London. 

 Royal Society, November 17.— Prof. C. S. Sherring- 

 ton, president, in the chair. — P. A. MacMahon and 

 W. P. D. MacMahon : The design of repeating pat- 

 terns. The study and classification of repeating pat- 

 terns in space of two dimensions is founded upon the 

 simplest geometrical forms which happen to be re- 

 -ats. These are employed as bases and are sub- 

 -cted to specified transformations which depend upon 

 certain ccKitact systems between the sides which are 

 in contact in the assemblage. Repeats are of three 

 varieties: the block, the "stencil," and the "archi- 

 pelago." There is a further broad division into 

 normal and abnormal repeats. .\ thecwv of "com- 

 plementary repeats "' is established. A contour can 

 be drawn around ever\- normal repeat in an infinite 

 number of ways, such that the area within the con- 

 tour, which does not belong to the repeat, is itself a 

 repeat. The contour under specified conditions is 

 irself the boundary of a repeal, which is therefore a 

 >mbination of the original repeat and its comple- 

 mentary. Mr. G. T. Bennett finds that 'eveni- 

 Muadrilateral figure " is a repeat. — J. W. Nicholson : 

 A problem in the theon,- of heat conduction. The tem- 

 i>erature at any point in the external medium, and 

 the rate of loss of heat from a cylinder, the surface of 

 which is maintained, from some specified instant, at 

 a constant temperature for all subsequent time, is 

 found for anv instant bv the use of a generalised form 

 of the Bessel-Fourier double integral. A solution can 

 be obtained in a similar way when the temperature 

 maintained on the cvlindrical surface is not constant. 

 C. H. Lees : The thermal stresses in spherical 

 lells concentrically heated. Thermal stresses in the 

 aterial of a furnace of approximate spherical form 

 cue to differences of temperature, and the stresses due 

 "> pressures on the inside and outside surfaces, mav 

 '^ expressed in terms of the volume of the soherical 

 -urfnce through any rx^int or of its reciorocal. The 

 whole problem can be treated graphicallv. The in- 

 crease of stress due to sudden changes of temperature 

 of the inside surface is discus=ed. — R. .\. Fisher : The 

 mathematical foundations of theoretical statistics. 

 The most efficient statistic has the least standard 

 deviation ; the efficiency of any other statistic is the 

 ttio of number of observations required bv the most 

 rficient to that required by statistic under consideration 

 in order to obtain a value of the same accuracy. The 

 criterion of consistency applied to a method of estima- 

 tion is a special case of criterion of sufficiency, which 

 quires that the sufficient statistic shall include the 

 -vhole relevant information provided bv sample. Statis- 

 tics obtained by the method of maximum likelihood 

 nre always sufficient statistics. Their standard devia- 

 ion being easily calculated, the efficiency of any other 

 statistic of known probable error mav be found. — 

 F. P. White : The diffraction of plane electromagnetic 

 waves by a perfectly reflecting sphere. The series 

 ilution is transformed into a contour integral along 

 path of "steepest descents." and the value of this 

 integral is determined approximately. The results 

 obtained are in agreement with those obtained bv 

 other workers. — C. V. Raman and G. A. Sutherland': 

 The Whispering Galler\- phenomenon. Observations 

 made in the Whispering Galler\- at St. Paul's Cathe- 

 dral and in laboratory- experiments show that Ray- 

 leigh's theorv- of the phenomenon does not offer a 

 complete explanation. The single belt of maximum 

 intensity close to the wall contemplated by Rayleigh 

 is obtained only in the limiting case when the radius 

 of the reflecting circle is practically infinite in com- 

 parison with the wave-length. For more moderate 

 NO. 2717. VOL. 108] 



values of the radius of curvature there is a succession 

 of belts of alternately great and small intensir\-. The 

 slight deviation from the condition of strictly circuin- 

 ferential wave-propagation postulated by Rayleigh 

 gives rise to such effects. 



Linnean Society, November 3. — Dr. A. Smith Wood- 

 ward, president, in the chair. — J. Groves: Charophyta 

 collected by Mr. T. B. Blow in Ceylon. The col- 

 lection consisted of thirteen species, one of which was 

 regarded as new ; only one ot them occurred in 

 Europe. Manv of the specimens were obtained from 

 tanks which had been in use when large tracts of 

 countrv, which are now lying waste, were in cul- 

 tivation. 



Zoological Society, November 8. — Dr. A. Smith 

 Woodward, vice-president, in the chair. — R. 1. 

 Pocock : The external characters and classification of 

 the Mustelidae.— W. R. SherriB : Evolution within 

 the genus. Part i. Dendronephthya (Spongodes), 

 with descriptions of a number of species. 

 Part 2. Description of species (Alcyonaria) taken by 

 the Siboga expedition. — C. F. Sonntag : The com- 

 parative anatomy of the tongues of the mammalia. — 

 V. Lemuroidea and Tarsoidea. VI. Summarj- and 

 classification of the tongues of the Primates. — E. P. 

 Chance : Investigation of the laying-habits of the 

 cuckoo {Cuculus cauorus) and the life of the young 

 cuckoo. This communication was illustrated by a 

 striking series of kinematograph films and photo- 

 graphs. 



Cambridge. 



Philosophical Society, October 31. --Prof. Seward, 

 president, in the chair. — H. Hartridge : A new 

 method of testing microscope objectives. The focus- 

 sing points of rays from different zones, or the lateral 

 i displacements of an image formed by the rays from 

 different zones, are determined. For the latter method 

 either direct visual obser\ation may be used or the 

 displacements as recorded in a photographic plate can 

 be afterwards measured. — J. E. P. Wagstaff : (i) 

 Determination of the coefficient of viscosity of mer- 

 cury. (2) A laboratory method of determining Young's 

 modulus for a microscopic cover-slip. — J. L. Glasson : 

 Some peculiarities of the Wilson ionisation tracks and 

 a suggested explanation. The tracks of /3-particles 

 in the Wilson photographs form circular arcs of 

 random radii length and direction. This may be due 

 to magnetic fields produced by transient quasi-crystal- 

 line aggregations of water molecules. The existence 

 of many cases in which two or more tracks have 

 similar shapes supports these conclusions, as does 

 the periodicity of the ionisation and the curvature of 

 the o-ray tracks. Peculiar distributions of the a-rays 

 emitted from radium emanation suggest that the 

 atoms of emanation are polar, and that the field 

 is polarised. — ^W. Bumside : (i) Convex solids in 

 higher space. (2) Certain simply transitive permuta- 

 tion-groups. — G. H. Hardy and J. E. Littlewood : Some 

 problems of diophantine approximation. — W. J. 

 Harrison : The stability- of the steady motion of viscous 

 liquid contained between two rotating coaxial circular 

 cvlinders. — R. Whiddington : (i) Note on the velocity 

 of X-ray electrons. (2) A laboratory valve-method few- 

 determining the specific inductive capacities of liquids. 

 — Sir George Greenhill : Tides in the Bristol Channel. 

 — M. J. M. Hill: The fifth book of Euclid's 

 ■' Elements." — W. Wirtinger : A general infinitesimal 

 geometry-, in reference to the theory of relativity. 



Dublin. 

 Royal Irish Academy. November 14.— Prof. Sydnev 

 Young, president, in the rfiair. — T. Alexander and J. T. 

 Jackson : Polygons to generate diagrams of maximum 



