862 



NA TURE 



[December 23, 1922 



that of the a-particle emitted immediately afterwards 

 by the resulting thorium-A atom. Some remarkable 

 features on these tracks were explained as due to 

 the action of previously formed tracks in robbing 

 the air of its excess oi water vapour. (2) Photographs 

 of a-ray tracks showing short-range /i-rays radiating 

 from them — Bumstead's o-rays, of which photographs 

 were obtained by him in hydrogen. From the range 

 of the longest S-rays their velocity reaches values 

 twice that of the a-particle. The o-rays do not 

 appear on the last two centimetres of the a-ray 

 tracks. In the neighbourhood of the initial portions 

 of the a-tracks minute detached cloudlets are visible 

 — probably the tracks of /3-particles produced by 

 soft X-rays (K-radiations from atoms traversed by 

 the a-particle). — A. B. Appleton : The interpretation 

 of the pelvic region and thigh of Monotremata. An 

 extensive comparison of thigh musculature forms 

 an essential preliminary to the tracing of changes 

 in the form of the femur and pelvis among Tetrapoda. 

 The destination of nerve-fibres and their course in 

 regard to pelvic-girdle and muscles provide the best 

 guide to the identification of muscles. The myology 

 and nerve-distribution of various mammalian and 

 other tetrapod groups has been carried out as a 

 preliminary to the identification of Monotreme 

 muscles. Monotremata exhibit most of the character- 

 istics of the mammalian thigh. A somewhat divergent 

 evolution has taken place with retention of certain 

 reptilian features. The lesser trochanter of mam- 

 malia is a different structure from the internal 

 trochanter of reptilia. — A. B. Appleton and F. Goldby : 

 Observations on the innervation of the pubi-tibialis 

 (sartorius) muscle of Reptilia. In some species of 

 Lacertilia it is innervated from two nerve-trunks, 

 as in Sphenodon. This is regarded as due to fusion 

 of two muscle-elements. Certain Mammalia, Mono- 

 tremata and certain Carnivora almost reproduce 

 this form. In most other Mammalia, the pubi- 

 tibialis muscle is represented only by the sartorius 

 muscle (possibly also by the gracilis muscle), and the 

 function has changed. — W. Burnside : The axioms 

 of elliptic geometry. — W. M. H. Greaves : The 

 periodic solutions of the differential equation for 

 the triode oscillator. — C. G. F. James : Complexes 

 of cubics in ordinary space. 



Edinburgh. 



Royal Society, December 4. — Prof. J. W. Gregory, 

 vice-president, in the chair. — Sir J. A. Ewing : The 

 atomic process in magnetisation : further notes. A 

 modified form of atomic model has been made which 

 reproduces the distinctive features of both ferro- 

 and paramagnetism. Taken in conjunction with 

 Langevin's theory of diamagnetism, the new model 

 appears to offer a general clue to the process of 

 magnetisation in any solid body, whether ferro- 

 magnetic, paramagnetic, or diamagnetic. It is now 

 generally recognised that the electrons, in consequence 

 of orbital motion or otherwise, are in some wav 

 magnetic di-poles. If their grouping is not rigid 

 and allows individual electrons to have their magnetic 

 axes reversibly deflected against a strong controlling 

 force, we find the phenomena of paramagnetism. 

 As regards ferromagnetism, the group might be 

 initially unsymmetrical, having a resultant moment, 

 so that it could serve as the Weber element in a 

 ferromagnetic process. In that case the phenomena 

 of hysteresis are found when the group as a whole 

 turns from one position of stability to another. 

 The control under which such irreversible turning 

 lakes place is probably partly in the mutual action 

 between the outer shell of electrons of any one atom 

 and those of its next neighbours in the space-lattice, 



NO. 2773. VOL. I 10] 



as well as in the mutual action from atom to atom 

 of the groups which constituted the Weber elements. 

 The magnetic axes of the groups tend to orient 

 themselves in rows. At first, the group of electrons 

 in each atom is deflected reversibly through a small 

 range, after which there is a break away, and new 

 rows are formed with a more favourable orientation. 

 The control which causes the range of reversible 

 deflection to be verv narrow (as, for example, in 

 iron) is ascribed to the forces (not exclusively magnetic) 

 between electrons in juxtaposition in the outer 

 shells of atoms. The contiguous atoms are regarded 

 as turning simultaneously under the influence of 

 the applied field, first reversibly through a small 

 angle, and then irreversibly into new lines, which, 

 in an iron crystal, are inclined at 90 ° or 180 to the 

 old ones. When all the groups are turned in one 

 direction, the magnetism is what is called saturated, 

 but there may be a further increase of the magnetism 

 through the reversible turning of the individual 

 electron axes within any group. — A. P. Laurie : 

 Experiments with a model to illustrate the com- 

 bination of two atoms consisting of magnetons 

 round a positive nucleus. If two atoms composed 

 of rings of magnetons placed radiallv round a positive 

 nucleus approach each other, then the magnetic lines 

 of force between the two atoms are such that there 

 must be two places of equilibrium for the two nearest 

 magnetons — one in which they are when the atoms 

 approach, and the other the position at right angles 

 to this holding the two atoms together by means 

 of the outer electrons. A model to illustrate this (Figs. 

 1 and 2) was constructed with four fixed coils to repre- 

 sent two of the outer magnetons of two separate atoms 



— » - - 



• i \ 



I l 



Fig. i. Fig. =. 



Two atoms before combination. Two atonic after combination. 



and with two moving coils, each able to turn on its 

 own centre and on a common centre between them. 

 On passing an electric current through the svstem 

 the moving coils always arranged themselves in one 

 position or another at right angles according to the 

 placing of the four fixed coils. This suggests a new 

 theory of valency — a valency not depending on the 

 number of magnetons in the outer shell, but on the 

 number of groups of three magnetons. There would 

 be primary, secondary, and tertiary valencies, the 

 combination of two atoms at once producing fresh 

 groups of three electrons which lead to new valencies. 

 An explanation of chemical combination is offered. 

 — A. E. M. Geddes : Observations on the structure 

 of the hydrogen lines Ha and Hp. Sommerfeld's 

 theory demands a constant frequency separation of 

 the components of spectral lines. The results 

 obtained tend to indicate a gradual decrease in the 

 separation. This appears to support M'Lennan's 

 idea that the frequency separation gradually 

 diminishes and vanishes at the limit of the Balmer 

 series. — D. M. V. Sommerville : Division of space 

 by congruent triangles and tetrahedra. The various 

 ways in which it is possible to divide the plane into 

 congruent triangles, and space of three dimensions 

 into congruent tetrahedra, is discussed. — Sir Thomas 

 Muir : The theory of alternants from 1896 to 191 7. — 

 H. W. Turnbull : Double binary forms. The (m, n) 

 form -(",,) (".)a hk z m ~ h z 1 "~ k , o'(h'(m, o'<.k'<n is binary in 

 both independent variables z, z l . Relative to the 

 independent linear transformations from z to z lt 



