July i, 1922] 



NA TURE 



2 3 



Quantum Mechanism in the Atom. 



AT a meeting of the Royal Society of Edinburgh 

 on Ma)- 8 Prof. E. T. Whittaker read a paper 

 on the quantum mechanism in the atom (since 

 published in Proc. Roy. Soc. Edin., vol. xlii. pp. 

 129-142). 



Prof. Whittaker shows that it is possible to explain 

 quantum phenomena satisfactorily in terms of the 

 classical electrodynamics without postulating any 

 structure in the atom beyond that by which it 

 is customary to explain induced magnetisation. 

 The author considers the effect of an approaching 

 electron in producing a " magnetic current " in the 

 atom ; up to a certain velocity of approach the electron 

 does not get beyond the atom but suffers an " elastic 

 impact" which repels it without loss of energy. When, 

 however, the velocity of approach exceeds this critical 

 value the electron passes through the magnetic atom 

 and gives to it energy of exactly that amount or 

 quantum which corresponds with the critical velocity. 

 The transformation of this energy into radiant energy 

 can be explained by generalising the conception ; 

 thus the magnetic current becomes equivalent to a 

 charged condenser, partaking of the nature of a 

 Hertzian oscillator. By a simple mathematical 

 process, combined with the assumption that the 

 oscillators in the atoms are similar to each other in 

 structure and differ only in scale, the equation liv = U 

 can be established, giving Planck's relation connecting 

 the frequency, ", of the emitted radiation with the 

 amount of kinetic energy, U, absorbed from the 

 bombarding electron. A more definite form to the 

 quantum mechanism is given by linking a conducting 

 circuit with the magnetic structure. Photo-electric 

 phenomena can be interpreted on the basis of this 

 theory, and Bohr's theory of series-spectra likewise 

 finds an explanation. 



Sir Alfred Ewing suggested that instead of follow- 

 ing Prof. Whittaker in leaving the magnetic atomic 

 model at a certain point there is perhaps an advantage 

 in not dropping the model, especially as it seems to 

 give an immediate explanation of the manner in 

 which oscillations are set up as the electron parts 

 with its quantum of energy. In the Ewing magnetic 

 model the central magnetic system or wheel is 

 controlled by an outer system or ring. When an 

 electron passes through and escapes it gives an 

 impulse producing relative angular displacement of 



inner wheel and outer ring, and the mutual magnetic 

 forces tend to restore the original configuration. 

 Oscillations are set up which expend their energy 

 in emitted radiation. Conversely, in an atom in 

 which oscillations are going on, an electron may be 

 ejected (photo-electric effect). In being ejected it 

 exerts an angular impulse which stops the oscillation 

 and deprives the atom of the quantum of energy 

 originally absorbed through resonance. 



Dr. H. S. Allen directed attention to the fact that 

 in Prof. Whittaker's " calamoids," or four-dimensional 

 tubes of electromagnetic force, as well as in the 

 Ewing magnetic model, magnetic forces rank on an 

 equality with electrostatic forces. The number of 

 magnetic tubes associated with Prof. Whittaker's 

 magneton must be an integral number of times the 

 unit quantum tube of magnetic induction. More 

 satisfactory is a modified form of the quantum 

 mechanism, in which two ring electrons are placed 

 near together on the same axis, the electromagnetic 

 force between them being repulsive. Such models 

 cannot, in Dr. Allen's opinion, " reconcile " quantum 

 dynamics with classical dynamics. 



Dr. R. A. Houstoun suggested the advisability of 

 testing Prof. Whittaker's theory by an appeal to 

 numerical calculation, introducing, for example, 

 definite values of the frequency and calculating the 

 corresponding size of the molecule. The results 

 appear to be satisfactory considering the simple 

 nature of the assumptions made. It seems that the 

 reciprocity which exists between electric and magnetic 

 quantities in the electromagnetic wave must be 

 extended to atomic structure. 



Prof. Peddie remarked that the value of Prof. 

 Whittaker's idea does not lie in its being an " only 

 possible " one, for other possibilities exist. Its 

 importance rests on the fact that the idea is a new 

 one, giving for the first time an action on an electron 

 which is not reversed in direction when the electron 

 passes through an atom. A " perfectly elastic " 

 collision seems to be attainable only by implicitly 

 denying collisional radiation, which leaves part of 

 the essential mechanism undescribed. The inter- 

 actions of the atomic charges, ether and the 

 " magnetic currents," may perhaps introduce diffi- 

 culty regarding atomic subjection to the Newtonian 

 first law of motion. 



The Second Royal Society Conversazione. 



'THE second conversazione of the Royal Society 

 * this year was held in the rooms of the Society 

 at Burlington House on the evening of June 20, when 

 the president, Sir Charles Sherrington, with Lady 

 Sherrington, and the officers of the Society, received 

 a large number of fellows and guests. Many interest- 

 ing scientific instruments and specimens were shown, 

 several of which were exhibited at the first con- 

 versazione held on May 1 7, and some were briefly 

 described in Nature of May 27, p. 693. Below are 

 brief descriptions of other noteworthy exhibits. 



Some selections from the contents of large pre- 

 historic cooking-places at Buckenham, Tofts Park, 

 Norfolk, were shown by Miss Nina F. Layard. The 

 specimens were found by Miss Layard and Miss M. F. 

 Outram in 1921-1922, and they include hearth-stones, 

 heating-stones, bones and teeth of animals, fragments 

 of pottery, flint flakes and implements. Mrs. Clayton 

 exhibited a Roman bronze measure of capacity, made 

 under Domitian, which was found during draining 



NO. 2748, VOL. I IO] 



works in the vicinity of the Roman Wall, three miles 

 east of Gilsland, Northumberland. 



A simple form of respiration meter was exhibited 

 by Mr. H. F. Pierce. Two bellows are mounted on 

 a vertical shaft, one of which measures the volume 

 of inspired air, the other the volume of expired air. 

 The latter is measured at a temperature of 37-2° C. to 

 avoid error due to condensation of contained moisture. 

 Respiration is recorded quantitatively upon a smoked 

 drum. The moving parts are made very light and 

 valves are operated electrically. 



Mr. G. C. Robson had an exhibit showing that a 

 highly differentiated character which appears dis- 

 continuously in the parthenogenetic gastropod, 

 Paludestrina jenkinsi, does not reappear in two 

 generations bred from parents showing this character. 

 There is evidence that this character cannot be com- 

 pared with an ordinary " fluctuating " variation. 

 The Royal Botanic Gardens, Kew, showed a double 

 coconut, or Coco de Mer, from the Seychelles, which 



