848 



NATURE 



[February 24, 192 1 



Societies and Academies. 



London. 



Royal Society, February 3. — Prof. C. S. Sherrington, 

 president, in the chair. — Dr. G. B. Jeffery : The field 

 of an electron on Einstein's theory of gravitation. 

 Equations are obtained for the motion of a single 

 electron about an atomic nucleus. If a ray of light 

 passes through the field of the electron, provided that 

 the distance of closest approach is not too small, the 

 ray is deflected towards the electron. For closer 

 approach the sense of the deflection is reversed until 

 in the limit the ray is reflected back again along its 

 original path. These results are used to ascertain 

 whether any possible electric field of the sun would 

 produce a measurable effect on the crucial phenomena 

 of Einstein's theory. It is found that, while the 

 sun's electric field would tend to diminish the dis- 

 placement of the spectrum lines, the field required 

 to oroduce compensation is of the order of 10" volts 

 per cm. at the sun's surface. — Dr. M. N. Saha : A 

 physical theory of stellar spectra. Elsewhere a theory 

 of thermal ionisation (and partly of thermal radia- 

 tion) of gaseous elements has been developed and 

 applied to the explanation of the ionisation observed 

 in the solar chromosphere, and the absence of certain 

 elements from the Fraunhofer spectrum. In the 

 present paper the theorv has been extended towards a 

 physical explanation of the ordered gradation in the 

 spectra of stars. The stellar data, particularly those 

 accumulated by the Harvard College Observatory, are 

 discussed from the point of view of the present theory, 

 and it has been shown that the varying spectra of 

 stars can be explained as functions of a single physical 

 variable, viz. the temperature of the stellar atmo- 

 sphere.— W. F. Darke, J. W. McBaIn, and C. S. 

 Salmon : The ultra-microscopic structure of soaps. 

 The ultra-microscopic observations of Zsigmondy and 

 Bachmann on soan-curds have been confirmed, inter- 

 preted, and extended. The kinematograph has been 

 employed as an aid in elucidating the formation and 

 disaopearance of the various structures observed. The 

 curds of sodium, notassium. and hydroeen soaps are 

 described and discussed. — Dr. J- Mercer : Linear 

 transformations and functions of positive type. The 

 paper contains dovelonments of the theory of linear 

 functional transformations as developed by F. Riesz 

 in his paper " Untersuchunp'en uber Systeme inte- 

 grierb.aur Funktionen " (Math. Annalen, vol. Ixix., 

 pp. 440-97)- 



Mineralogical Society, January 18. — Mr. A. Hutchin- 

 son, vice-president, in the chair. — A. F. Hallimond : 

 The olivine group. Since the discussion of the densi- 

 ties by Thadd(5ef in 1S96, and of the optical constants 

 by Backlund in igog, numerous additions have been 

 made to the published data. These have been col- 

 lected and the most probable values for the pure corn- 

 pounds obtained. The molecular volume of monti- 

 cellite is slightlv greater than the mean between 

 forsterite and y-CajSiO,. For the complex mixtures 

 the density and mean refractive index yield additive 

 relationships, but the birefringence and axial ratios 

 follow no additive law. The conditions of plotting 

 which must be observed if the variation of an addi- 

 tive property with composition is to be expressed by a 

 straight line were briefly summarised. — W. A. 

 Ricliardgon : A method of rock-analysis diagrams 

 based on statistics. Oxide variation diagrams, similar 

 to those employed bv Dr. Harker, can be used for 

 expressing the chemical relations of rock groups and 

 individuals. The diagrams obtained from plotting 

 Iddings's selected analyses rave the maximum varia- 

 tion for all rocks.— L.' J. Spencer; Identity of Trech- 



NO. 2678, VOL. 106] 



mann's "/S-tin" with stannous sulphide. A re- 

 examination of the original material described by 

 C. O. Trechmann in 1879 as an orthorhombic modi- 

 fication of tin proved that he made his crystallographic 

 determinations on crystals of one kind (viz. stannous 

 sulphide), whilst the chemical analysis was made on 

 crystals of another kind (viz. metallic tin). Tin is, 

 therefore, dimorphous and not trimorphous, "white 

 tin" being tetragonal and "grey tin" cubic. Ortho- 

 rhombic crystals of stannous sulphide (SnS) and tetra- 

 gonal crystals of iron stannide (FeSnj) from tin fur- 

 naces and rhombohedral crystals of tin arsenide 

 (SnjAsj) isolated from a tin-arsenic alloy were 

 described. 



Linnean Society, January 20.— Dr. A. Smith Wood- 

 ward, president, in the chair.^E. H. C. Wal«li : 

 Lhasa and Central Tibet. The lecturer gave first a 

 brief description of the country, the people, the 

 religion, and the government. The country extends 

 1600 miles in its greatest breadth, and 800 miles 

 in its greatest width, from the Koko Nor to the 

 southern bend of the Takiang or Blue River ; the 

 superficial area is more than a million square miles, 

 comprises the highest portion of the earth's sur- 

 face, and is bounded on its southern frontier by the 

 Himalayas, the loftiest chain of mountains in the 

 world. The Tibetans are a Turco-Mongolian race and 

 speak a monosyllabic language ; it is believed that 

 they originally lived in China, but were driven out by 

 conquering races. They are mentioned as early as 

 770 B.C., when they were at war with the Chinese. 

 There are two acknowledged forms of religion, the 

 Buddhist and the Bon, pronounced Pon ; the latter 

 has adopted some of the formulas of the former, 

 but reversed them, as in the case of the 

 "Swastika" or fyle-fot cross; also the Buddhist 

 prayer- wheel , with its invocation "Om mani padme 

 hum." The two sects lived peaceably side by side. 

 The Dalai Lama, the Pope of the Lamaist Church, is 

 believed to be a continuous incarnation of previous 

 Dalai Lamas, and of the Deity Avalokiteswara upon 

 earth. When a Dalai Lama dies his reincarnation 

 has to be looked for in some infant born shortly 

 afterwards, and this is ascertained by the chief oracle 

 indicating the part of the country and some clues, and 

 the result of local inquiries is then reported to the 

 leading Lamas, who decide by lot the actual child to 

 be educated as the Dalai Lama. 



Physical Society, January 28. — Sir W. H. Bragg, 

 president, in the chair.— Prof. H. Nagaolia : The 

 magnetic separation of neon lines and Runge's rule. 

 The results of an investigation of the Zeeman effect 

 for neon lines are given. The departures from 

 Runge's rule — that the magnetic separation of the 

 lines are aliquot parts of the separation of the normal 

 triplet — are discussed. It is concluded that such dis- 

 crepancies are due to variations of the ratio ejm. — 

 E. V. Appleton : A method of demonstrating- the retro- 

 active property of a triode oscillator. The author, 

 following Vallauri, gives an approximate treatment of 

 the conditions which give rise to retro-action between 

 the grid and anode circuits of a triode valve, and 

 describes an arrangement of circuits whereby the 

 property can easily be demonstrated to a large audi- 

 ence. — Dr. D. Owen and R. M. Arclier : The quick- 

 ness of response of current to voltage in a thermionic 

 tube. Steady voltages were applied between the hot 

 and cold electrodes of a thermionic tube for intervals 

 of time varying from oooooi second to a minute or 

 longer. The mean current during the interval was 

 measured by the Wheatstone bridge, using a null 

 ballistic method. Two types of theimionic tube were 

 employed, one at a high gas pressure and the other 



