December 23, 1920] 



NATURE 



553 



it is hoped will be as useful and interesting to manu- 

 facturers as to men of science. Sixteen lectures of a 

 popular nature dealing with various aspects of recent 

 researches on the structure of matter and on the origin 

 and characteristics of radiation will be delivered by- 

 Prof. J. C. McLennan, who will deal chiefly with 

 the results of the experimental investigations which 

 have been made in numerous branches of the subject, 

 concluding with an account of the production and 

 uses of helium. The conference will be opened on 

 Wednesday, January 5, by Sir Robert Falconer, 

 president of the University of Toronto. 



Societies and Academies. 



Lo.NUO.S'. 



Royal Society, December 9. — Prof. C. S. Sherring- 

 ton, president, in the chair. ^Lord Rayleigh : Double 

 refraction and crystalline structure of silica glass. 

 .Mthough glasses in general have no double refraction, 

 except that due to bad annealing, yet silica glass is 

 found to have a doubly rcfractmg structure which 

 cannot be so accounted for, and must rather be 

 regarded as crystalline. The double refraction is very 

 weak, of the order of 1/60 that of crystalline quartz. 

 In a mass of silica which has been melted, but not 

 drawn or blown, the structure consists of doubly 

 refracting grains with dimensions of about \ mm., 

 oriented at random. If the grained niaterial is drawn 

 out while soft, the grains are elongated into cTvstal- 

 line fibres or ribbons. Fused silica sometimes con- 

 tains isolated, small inclusions of quartz with angular 

 outlines which have escaped vitrification. These are 

 conspicuous in the polariscope by the strain effects 

 thev produce in the surrounding glass. — Prof. J. \V. 

 NicboiMn and Prof. T. R. Merlon : The effect of 

 asymmetry on wave-length determinations, (i) The 

 apparent displacement of an unsymmetrical spectrum 

 line caused by the finite resolving power of the 

 spectroscope can be calculated on certain simple 

 a-isumptions. (2) The displacement is independent of 

 the actual widths of the lines. (3) It is considered 

 that the general practice of measuring spectrum lines 

 to a degree of accuracy far transcending the resolving 

 power is not justified. --Prof. T. R. Merlon : The effect 

 of concentration on the spectra of luminous gases, 

 ("erlain spectroscopic phenomena appear to be asso- 

 ciated with the concentration of the radiating atoms 

 in the source. .An increase in concentration may 

 result in a broadening of the lines, a change in the 

 structure of the lines, and changes in the relative 

 intensities. Sources containinp lithium exhibit these 

 three phenomena, and the broadening is familiar in 

 sodium flames. !< study has been made of the be- 

 haviour of sources containing sodium and lithium. 

 The results seem to exriudi- a temporary association 

 of atoms as the cause of the changes, for the nddition 

 of large quantities of sodium to a source containing a 

 trace of lithium produces no change in the lithium 

 ipectra. Mixtures of hv<lrogen and helium have also 

 been investigated. The broadened lines of both these 

 elements from vacuum tubes excited by condensed dis. 

 charges are arcounted for romplelelv bv the electrical 

 resolution of the lines bv the electric fields of neii'h- 

 lK)uring charged particles. -Prof. K. W0»o« : The 

 measurement of low magnetic susceptibility bv 

 an instrument of new type. The paper deals 

 with the design, construction, and working of 

 an instrument for the measurement of sus- 

 ceptibilitv (of low order) over a wide range of mat!- 

 netir force, and thus avoids the diffirultv met with 

 in the Curie balance, the defections of which follow 

 the square law, and. in fart, limit the measurement 

 of suscentibllitv of a given "inecimen to a verv narrow 

 range of magnetic force. The force due to torsion in 



NO. 2669, VOL. IO6I 



a suspending fibre is replaced by an electromagnetic 

 system in which the mechanical force is due to two 

 components — one proportional to the magnetic force 

 impressed upon the specimen and the other variable 

 if the susceptibility varies. The expression for the 

 susceptibility is that of the reciprocal of a resistance 

 multiplied by a constant, and thus the instrument 

 lends itself to great accuracy in the detection of varia- 

 tions in susceptibility.— Prof. \V. T. David : The 

 internal energy of inflammable mixtures of coal-gas 

 and air after explosion. In the first part of this paper 

 an empirical law of cooling of exploded mixtures of 

 coal-gas and air contained in a closed vessel has been 

 formulated. This is based upon measurements of the 

 heat loss bv conduction and by radiation made during 

 the explosion and later cooling of the inflammable 

 mixtures. In the second part the heat-loss measure- 

 ments have been applied to the estimation of the 

 internal energv of the gaseous mixtures at the moment 

 of maximum temperature and at various stages during 

 cooling. — Prof. \. McAnlay : Multenions and differen- 

 tial invariants. The paper is a summary of the pro- 

 perties of a linear associative algebra suitable for 

 electromagnetic relations, differential invariants, and 

 relativity. There are n fundamental units, otherwise 

 it is the same algebra as that considered in a p.iper 

 by VV. J. Johnson and read to the Royal Society on 

 November 20, iqig. 



Arlilolelian Society, December 6.— Prof. T. P. Nunn 

 in the chair.- Prof. W. P. Montague: Variation, 

 heredity, and consciousness : a mechanist answer to 

 the vitalist challenge. It was attempted to show that 

 it is possible to point out a solution of the problems 

 of phvlogeny, ontogeny, and consciousness, statable 

 in mechanistic terms, which provides full satisfaction 

 to the demand of the vitalist that the purposive and 

 psvchic characters of life shall not be reduced to an 

 ep'iphenomenal status of dependence upon blind pro- 

 cesses. The occurrence of useful variations in the 

 germ-plasm in greater frequency than is explicable 

 on recognisable mechanistic principles may be ex- 

 plained bv the conception of biological vectors, 

 according to which the unpurposed, yet purposeful, 

 products of telogenesis in the germ-plasm and in the 

 brain, when occupied with creative imagination, are 

 results of a system of protoplasmic stresses. The 

 problem of the many hereditary determinants in the 

 minute germ-cell may be met by conceiving the germ 

 as a system of superforces or superimposed stresses 

 which are the embodiinents of a manifold of in- 

 visible intensive determinants equal in richness to 

 the serial events of (he germ's ancestral past, and 

 capable of reproducint; its pattern by induction during 

 embryonic growth. The problem of explaining mind 

 in physical terms was met by suggesting that the 

 structure of conscious life is analojjous to the struc- 

 ture of life in general, except that the system of 

 cerebral superforces in which the past is stored up in 

 the present is composed of traces of potential energy 

 acquired by the brain through the transformation of 

 the kinetic'energies of sensory nerve-currents. S new 

 rntegory, "nnergv," was proposed ns a measure of 

 the form of durational being produce<l whenever the 

 energv of motion is tr.in-furm.il into Ihr invisihte or 

 potential phase. 



LInncan Society. Derenilier <).- Dr. \. Siniili U'lxxl- 

 ward, presidi-nt. in the chair.— Prof. E. S. Goodrich: 

 Hymenopterous parasites of grain-infesting insects.— 

 I,. ^'. Lcder-tiarland : Plants from Dnrfur collected by 

 Capt. l.ynes, R.N., with remarks on their geo- 

 graphical distribution. Dr. B. Daydon Jackion : The 

 Norsemen in Cnn.ida in A.t>. looo, with the pl.ints 

 they re|)orte«l. The course followed by the Not 

 wa« narrated, from their colonies in Greenland, 1 



