November 28, 1912] 



NATURE 



369 



any existing drift of the asther relatively to the sun. 

 The existence of such molecules in space may be 

 accounted for by their continual expulsion from the 

 sun and stars, and it is obvious that, if the aether 

 is at all capable of offering any resistance to the 

 passage of such materials, the molecules would even- 

 tually take up the motion of the aether relative to the 

 sun. Then to determine the motion of the resisting 

 medium would bo, in any case, to determine the rela- 

 tive motion of the ather. Owing to their very small 

 density comets would be the most likely celestial 

 bodies to indicate the existence of the resisting 

 medium. 



."Vssuming that the majority of comets really have 

 elliptic orbits, and are therefore following the sun 

 through space, the effect of a resisting medium would 

 be to drag their aphelia to the rear of the sun, i.e. 

 towards the anti-apex of the sun's path. 



.'\s bright comets probably owe their conspicuous- 

 ness to the fact that they are surrounded by enormous, 

 verv tenuous envelopes of gaseous material, the re- 

 sisting action should be more evident on them, and 

 on plotting the aphelia of a number of comets Prof. 

 Pickering finds that this is the case. The aphelia of 

 the brighter elliptical comets do appear to concen- 

 trate in a particular region of the sky, and this anti- 

 apex in regard to the resisting medium coincides 

 prettv closelv with the solar anti-apex. There are 

 some inconsistencies still to be accounted for, but on 

 the whole it would appear that these cometary aphelia 

 are drap'Sed to the rearward of the sun, thus indicat- 

 ing a drift of the resisting medium, and therefore of 

 the aether, in regard to the sun. 



Observations of Comets. — The Coinptes rendus 

 for November ii (No. 20) contain reports, from many 

 observatories, of observations of comets 1912b (Tut- 

 tle'sl and 1912c (Borrelly's). M. Borrelly states that 

 on November 3 the nucleus of his comet appeared to 

 be asymmetricallv nlaced in the coma, while M. Coggia 

 on Nov-ember 4 and 8 could detect no definite nucleus 

 but only a gradual brightening towards the centre; 

 in this he is confirmed by M. Esmiol, of the Mar- 

 seilles Observatory. Generally the comet is reported 

 as a round nebulosity, with a very indistinct or no 

 nucleus, and no tail ; during the early part of the 

 month the magnitude was about 9 or 10, and accord- 

 ing to the ephemeris it is now about two-thirds as 

 blight, and will continue to decrease. 



METEOROLOGY AT THE BRITISH 

 ASSOCIATION. 



THE leading feature of meteorological interest in 

 the proceedings at Dundee was the joint dis- 

 cussion with Section M, .Agriculture, on the applica- 

 tion of meteorological information to agricultural 

 practice. 



Dr. Shaw said that the annual loss to this country 

 through unfavourable weather might be put at 

 20,000,000?., and as forecasts must ultimately be fore- 

 casts for the whole globe, the amount of the loss 

 some portion of which meteorologists aimed at saving 

 for the British Empire far exceeded the estimate men- 

 tioned. But apart from forecasts, which aimed at 

 saving by preventive precautions, there was probably 

 much to be done in increasing efficiency by the 

 application of our present knowledge of climate. In 

 this connection the meteorologist wished to learn from 

 the agriculturist if he could make use of meteoro- 

 logical statistics, and in what form he wished the 

 statistics to be presented to him. There were, more- 

 over, certain questions the answers to which would 

 render possible considerable economies, and perhaps 

 save the aspiring farmer many disastrous experiences. 



NO. 2248, VOL. 90] 



Such questions were : " VVliat is the effect of climate 

 on crops?" "What deviations from the normal values 

 of the meteorological elements constitute a good or 

 bad farmer's year?" Mr. R. H. Hooker had made 

 some progress towards providing an answer to the 

 first question in his paper on correlation between 

 weather and crops, and he himself had investigated 

 the relation between autumn rainfall and yield of 

 wheat. Recently also Unstead had reached interesting 

 conclusions in connection with the world's wheat crop, 

 the polar limit of which depended upon the accumu- 

 lated temperature and the duration of daylight in the 

 summer months. 



Mr. Watt communicated some results which he had 

 obtained for the connection between rainfall and tem- 

 perature, and the yield of crops in Forfarshire. He 

 found that a dry June and July were favourable to 

 the potato crop, and warmth during that period was 

 also desirable. For oats, however, a cool June was 

 decidedly favourable. 



Dr. E. J. Russell spoke of the effect of climate on 

 plant life by direct action on the plant itself, and 

 indirectly through its action on the quality and texture 

 of the soil. Heavy rain washed out the nitrates in 

 the soil, while hot dry weather and frost conserved 

 them. At the end of the summer of 19 11 the soil 

 contained 3^ times the usual amount of nitrates, but 

 the heavy rains of the succeeding autumn and winter 

 washed out nine-tenths of them. 



Mr. R. M. Barrington, speaking as a practical 

 farmer, testified to the great utility of local observa- 

 tions in conjunction with the reports of the Meteoro- 

 logical Ofiice, and expressed the opinion that meteoro- 

 logy ought to be taught to every budding farmer. 



On the Tuesday morning Prof. Turner gave an 

 account of his investigation of periodicities in earth- 

 quake phenomena. He found evidence of a real period 

 of about 15 months and indications of a period of ii'76 

 months, which was also found in the rainfall at 

 Greenwich. He communicated also a paper by Mr. 

 J. I. Craig, in which the author showed that 

 Schuster's method of the periodogram and the method 

 of correlation were practically identical. 



Mr. E. M. Wedderburn gave an account of his 

 investigations of the temperature conditions in the 

 Madiisee in Pomerania and in Loch Earn. In both 

 cases the temperature changes were found to be 

 oscillatory and capable of explanation on the assump- 

 tion that the motion of the water in the lake was in 

 opposite directions above and below the level of 

 maximum rate of change of density. 



Miss White read two papers on the results for wind 

 and temperature obtained at the upper air station at 

 Glossop Moor during 1908, 1909. 



She found that the average velocity of the wind 

 changed from 5*0 m.p.s. (metres per second) at ground 

 level (335 m.), to ir8 m.p.s. at 1000 m., and to 

 i3"6 m.p.s. at 2000 m. above mean sea-level. The 

 velocities at all heights were greater in winter than 

 in summer, and greater also for occasions when the 

 surface pressure was below the average than for 

 occasions when it was above. The rate of increase 

 of velocity was greater for westerly than for easterly 

 winds. .At the surface it was approximately the same, 

 5 m.D.s. in both cases, but at 2000 m. altitude the 

 velocity was 16 m.p.s. for westerly winds compared 

 with 12 m.p.s. for easterlv. On the average, the 

 theoretical value of the gradient wind calculated from 

 the pressure distribution was reached by the actual 

 wind at an altitude of 650 m., or 300 m. above ground 

 level. 



In the second paper on temperature, the rate of 

 f.-ill with height was found to diminish from 8',° C. 

 per km. near the surface to 4^3° C. per km. at 



