352 



NATURE 



[November 26, 19 14 



light, and probably the action of the kathode rays is 

 not direct, but is due to the radiation of ultra-violet 

 light by molecules struck by them. The destruction 

 by the longer waves of daylight of effects produced by 

 the light of short wave-length is a phenomenon of 

 which many other examples occur. The paper was 

 illustrated by specimens of the coloured salts. 



Prof. Hicks spoke on the magneton as a scattering 

 agent for a and y8 particles. The paper dealt with 

 the orbits of charged particles coming into the field 

 of the magneton and the nature of the scattering was 

 explained. Prof. T. R. Lyle gave a demonstration of 

 a mechanical analogue of wireless telegraph circuits. 



On Wednesday morning a discussion took place on 

 the problems of Antarctic meteorology. The meeting 

 was fortunate in having the attendance of a number 

 of men of science who were personally familiar with 

 the Antarctic regions. Dr. G. C. Simpson, who 

 opened the discussion, dealt with the main problem 

 of the general circulation of the atmosphere in the 

 southern hemisphere. Dr. Lockyer has suggested 

 that there is an intense anticyclone over the Antarctic 

 continent from which cold air feeds into a ring of 

 large cyclones having their centres about 60° S., and 

 extending northwards as far as 40° S. Prof. Mein- 

 ardus also has postulated a series of cyclones over 

 the Southern Ocean travelling from west to east; but 

 he finds it difficult to accept anticyclonic conditions 

 over the continent, owing to the great excess of pre- 

 cipitation there which gives rise to the glaciers and 

 snowfields. From a detailed discussion of the condi- 

 tions in the Ross Sea area Dr. Simpson deduces that 

 the conditions over the continent are anticyclonic. 

 In the lower atmosphere the strong south-easterly 

 blizzards are the result of the large differences of 

 temperature between the barrier and the Ross Sea. 

 In the upper atmosphere the air feeds in again to the 

 Antarctic, as is shown by the cloud observations. 

 Meinardus's objection that in such a circulation the 

 precipitation would not exceed the evaporation is met 

 by a consideration of the great cooling of the air due 

 to radiation. With regard to the existence of a belt 

 of cyclones over the ocean, it appears quite impossible 

 to reconcile wind and barometer observations with 

 any circulation of wind about a low-pressure centre 

 moving from west to east. Further the simultaneous 

 barometer readings at Melbourne, New Zealand, and 

 Cape Adare give no certain indication of the same 

 cyclone affecting the northern and southern stations. 

 Dr. Simpson pointed out an important negative cor- 

 relation between the pressure at Cape Evans and in 

 Australasia, and urged the importance for Australian 

 meteorology of extensive observations on the Antarctic 

 continent. 



Mr. Griffiths Taylor pointed out the importance of 

 the proximity to Australia of this colossal source of 

 cold energy. The Antarctic continent is a much 

 greater land-mass than the Tibetan Plateau ; the latter 

 controls the monsoons and has an enormous effect on 

 the Indian climate. Meteorologically the influence of 

 the Antarctic tableland must be a most important 

 fact. Mr. Hunt. Captain Davis, Mr. H. T. Ferrar, 

 Prof. Rudmose Brown, and Mr. Gold also took part 

 briefly in the discussion. 



Prof. H. H. Turner then gave an account of the 

 work of the Seismological Committee, referring par- 

 ticularly to the situation of difficulty and anxiety 

 created by the death of Prof. Milne. Progress has 

 been made in the study of the distribution of earth- 

 quake centres, and Prof. Turner exhibited a map 

 showing^ the geometrical relation of these to the land 

 distribution on the globe. 



The sitting terminated early, as the members had 

 to leave for Sydney in the afternoon. 



The meeting at Sydney opened on Fridav, August 21. 

 NO. 2352, VOL. 94] 



Sir E. Rutherford spoke first on the origin and nature 

 of the -y rays from radium. Dr. Dyson then read a 

 paper on the stars near the north pole. So far a^ 

 proper motion is concerned, the area within 9° of the 

 pole is more thoroughly known than any other parr 

 of the sky, since the stars down to a faint limit of mag- 

 nitude, 3700 in number, were observed by Carrington 

 about 1^55, and have been re-observed at Greenwich 

 forty-five years later. This region has also been well 

 studied as regards magnitudes, both photographic and 

 visual, the photographic determinations having been 

 made at Greenwich and the visual determinations at 

 Potsdam. From the difference between the photo- 

 graphic and visual magnitudes (called the colour- 

 index) a classification according to spectral type is 

 possible. The proper motions of these stars have 

 been discussed by a statistical method with the view of 

 finding the distribution of the stars in space, particu- 

 lar attention being paid to the differences shown when 

 the stars are grouped according to colour-index. The 

 results which were given by Dr. Dyson are too com- 

 plex to be summarised here. They bring out in a 

 very striking way the fact that the reddest stars are 

 in the mean at a great distance from us — farther even 

 than the white stars — and that it is the stars in the 

 middle of the spectral series (types F and G) that 

 are closest to the sun. There is good evidence of a 

 considerable diminution in the density of the distribu- 

 tion of the stars between the distances of 100 and 500 

 parsecs, and the numerical results agree substantially 

 with the diminution found by Kapteyn. 



Messrs. Petrie and Chapman gave an account of a 

 curious actinic effect of the juice of Euphorbia peplus. 

 The dried juice acts on a sensitive photographic plate 

 in the dark. The effect can be transmitted through 

 black paper impervious to light or through thin 

 aluminium or gold foil. Yet no action on ionised air 

 can be detected with an electrometer. The property 

 is retained after prolonged heating, and a sample 

 dried five years ago is still as active as ever. The 

 juices of many other species of Euphorbia and similar 

 plants have been tested, and have been found to have 

 no comparable action. 



Prof. A. Gray read a paper on the attractions of 

 ellipsoidal shells. The principal theorems in the attrac- 

 tions of ellipsoids were deduced by a new and elegant 

 geometrical method. 



Papers were also read by Prof. O. U. Vonwiller on 

 the photo-electric effect in selenium, and by Prof. 

 W. G. Duffield on the pressure upon the poles of a 

 carbon arc. 



The next meeting was on Monday afternoon, August 

 24. Prof. Turner gave a paper on discontinuities in 

 meteorological phenomena. The usual methods of 

 harmonic analysis proceed on the assumption that the 

 periodicities looked for persist through the time 

 covered by the observational data. In the case of 

 certain astronomical phenomena, particularly the sun- 

 spot cycle, Prof. Turner had arrived at the conclusion 

 that abrupt discontinuities took place from time to 

 time, a change of period taking place at the dis- 

 continuity. A simple method was described by which 

 such discontinuities could be detected, and the evidence 

 suitably exhibited. The method was illustrated by 

 applying it to rainfall and other meteorological data 

 for which long records were available. Breaks in the 

 period are found to occur about every seven years. 

 These critical years were determined independently 

 from three separate sets of data, and a good general 

 agreement exists between them. 



Prof. Eddington gave an account of a determination 

 of the oblateness of the stellar system. It is well- 

 known that the distribution of the stars is decidedly 

 flattened towards the plane of the Milky Way, and 

 recent counts of stars, made by Chapman and Melotte 



