49 s 



NATURE 



[October 12, 191 1 



T 1 



MATHEMATICS AND PHYSICS AT THE 

 BRITISH ASSOCIATION. 

 "HE address of the president of Section A, Prof. H. H. 

 Turner, has been already printed in this journal 

 (August 31, p. 289). 



Cosmical Physics and Astronomy. 



The address was followed by a meteorological paper by 

 Prof. VV. J. Humphreys (of the U.S. Weather Bureau) on 

 the earth as a radiator. Since our climates arc not now 

 perceptibly growing either colder or warmer, the total 

 amount of heat received by the earth is substantially equal 

 to the loss during the same time. But this statement 

 does not apply to limited regions; and therefore to map 

 the earth as a radiator it is necessary first to obtain 

 temperature records within the isothermal region, where 

 radiation alone is the controlling factor. From the experi- 

 mental results the author deduces that the outward radia- 

 tion is least near the equator, where the inward radiation 

 is greatest, and greatest in temperate latitudes, a secondary 

 minimum at the pole being indicated by the ascents in 

 high latitudes. In the discussion it was pointed out that 

 the results depend largely on the assumption that the 

 atmosphere acts as a "grey" body. The values might 

 be subject to considerable correction for irregularities °in 

 the absorbing power for different spectral regions. Dr 

 Shaw directed attention to the need for examining the 

 influence of different thicknesses of water vapour in the 

 atmosphere, and considered that reflection from cirrus 

 clouds would introduce a considerable disturbing influence 

 A suggestion by Prof. Hicks that possibly the results were 

 a consequence of the preponderating amount of ocean near 

 the equator was met by Dr. Humphreys replying that the 

 same results were obtained over ocean as over land. 



Mr. L. Vegard, of Christiania, contributed a sug- 

 gestive paper on the radiation producing aurora 

 boreahs, m which he starts from Birkeland's view that 

 aurora; are caused by electric solar radiations, and 

 endeavours to deduce the properties of these radiations, 

 r-rom the form and structure of the luminosity he infers 

 that the electric radiations behave as though they are 

 a rays. It is found, from the relation between range and 

 velocity, that a rays will get down to heights varying 

 between 70 and 300 km., which agrees with observation? 

 I-urther, calculations show that a ravs will strike the 

 atmosphere at an angular distance from the magnetic 

 axis of about 17 , which gives the right position of the 

 auroral zone. The equidistant bands so characteristic of 

 the draperies he explains by assuming groups of homo- 

 geneous rays, starting under the same initial conditions, 

 such as would be provided bv radium and its disintegra- 

 tion products in the sun. The author made a strong cW 

 for his explanation of these interesting phenomena. 



Dr. W. N. Shaw communicated an account of the 

 thunderstorms of July 28 and 29. The London storm on 

 July 28 was accompanied by a squall of wind which 

 reached fifty-four miles an hour at South Kensington, and 

 the storms on July 29, which occurred over nearly the 

 whole of England and Ireland, were preceded by violent 

 squalls which raised clouds of dust, particularly notice- 

 able m South Wales. At Watlington (Mr. W. H. Dines) 

 the disturbance occurred while the passage of a depression 

 was in progress, and the barograph curve took an M form 

 instead of the usual • The records of temperature, 

 wind direction, and rainfall have still to be examined with 

 the object of tracing the physical processes underlying the 

 disturbance. 



In the same department Commander Campbell Hep- 

 worth communicated a paper on the effect of the 

 Labrador current upon the surface temperature of the 

 North Atlantic, and of the latter upon the air tempera- 

 ture and barometric pressure over the British IsIps. The 

 purpose of the paper was to show the importance of the 

 Labrador current in modifying the influence of the Gulf 

 Stream. 



Dr. Shaw showed models representing air currents up to 

 heights of 10 kilometres which had been obtained from the 

 'lions of pilot balloons made at Ditchnm Park by 

 Mr. _ Cave. _ The models showed some of the types of 

 motion which occur, and were very instructive to those 

 unfamiliar with the details of upper-air observations. 

 NO. 2189, VOL. 87! 



Dr. Humphreys read a paper on the water vapour in the 



atmosphere on clear days, a quantity of great importance 



in the determination of the solar constant. He found a 



value of 87 per cent, of the value found by Hann from 



ions made in all kinds of weather. 



-Mr. Gold gave a brief account of the results obtained 

 from the ascents in Ireland, undertaken by the committee 

 for the investigation of the upper atmosphere. Three 

 successful ascents had been made from Mungret College, 

 Limerick, in the present year, and on July 6 values for 

 the temperature had been obtained up to 21 km. 



Dr. Dickson put forward the suggestion that the treat- 

 ment of general atmospheric circulation might be simplified 

 by taking the equatorial circulation to form a system by 

 itself. It was pointed out in the discussion that general 

 dynamical considerations rendered such an hvpothesis un- 

 tenable. 



Mr. Craig read a paper by Dr. Ball and himself on 

 the use of diagrams in the classification of climate. The 

 diagrams dealt with temperature and humidity, and showed 

 the annual course of these elements by a' single closed 

 figure for each of a selection of places from different parts 

 of the world. The shape and orientation of the figure 

 varied with the climate, and showed at once its principal 

 features. Mr. Craig pointed out how they could be used 

 not only by the man who was considering his health, but 

 also in connection with such problems as cotton-growing. 



Prof. J. Milne presented the sixteenth report of the com- 

 mittee on seismological investigations. Of the many 

 interesting things in this report we may instance the 

 observations on tidal load at Ryde in the'lsle of Wight. 

 By means of an instrument installed in a cellar in the 

 Royal Victoria Yacht Club at Ryde and with its boom 

 oriented east and west, a 10-foot tide in the Solent is 

 found to produce an angular deflection of 085". At 

 Bidston a 10-foot tide gives at a distance of two miles a 

 tilt of 02". A curious feature of the Ryde photograms is 

 the flatness of many of the crests and hollows of the 

 deflections, which seems to indicate that from time to time 

 the water remains high (or low) for several hours. When 

 the boom was pointed north, or toward the advancing and 

 retreating tide, the resulting photograms were practically 

 straight lines. 



Prof. H. H. Turner read a note on the periodogram of 

 earthquake frequency from seven to twenty years, in which 

 he investigated by Schuster's methods the possibility of 

 periodicities in earthquakes, making use of the data in the 

 " Catalogue of Large Earthquakes " recently edited by 

 Prof. Milne. Within the range of periods examined, the 

 only chance of a real periodicity is one of nineteen years, 

 suggesting a nutational effect depending on the moon's 

 nodes. 



A paper by Mr. F. Napier Denison, on horizontal 

 pendulum movements in relation to certain phenomena, 

 was read by Prof. Milne, who also read one on the solar 

 cycle, the Jamaica rainfall, and earthquakes cycles, bv 

 Mr. Maxwell Hall, dealing with observations extending 

 from 1S70 to iqio. Excepting a rainfall minimum in 

 the minima for rainfall follow sun-spot maxima and 

 minima by il- or 2 years. The rainfall maxima are more 

 irregular. The earthquake maxima follow solar maxima 

 by 2 years, while the minima follow solar minima bv 

 2 or 3 years. Prof. O. Pettersson followed with a very 

 interesting paper on parallactic tides set up in the bottom 

 layers of the sea by the moon (see report of Section E). 



Stellar Distribution. 



The proceedings on Tuesday. September 5, commenced 

 with a discussion on stellar distribution and movements, 

 opened by Mr. A. S. Eddington, who stated that in attempt 

 ing to form a conception of the structure of the univi rse 

 as revealed by modern researches, we have to take into 

 account the following principal phenomena. The great 

 mass of the stars are distributed in a lens- or bun-shaped 

 system, in which our sun occupies a nearly central posi- 

 tion ; round this, and in the same plane, are coiled the 

 clusters, which make up the Milky Way. In the central 

 parts of this the stars form two great streams moving in 

 opposite directions; this is most easily explained as being 

 the result of two more or 1 .endi nt systems of stars 



