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NATURE 



[March 24, 192 1 



The statutes of the council exclude members of 

 "enemy " countries from every "international " union 

 formed under its auspices until 193 1. After that date 

 the statutes may be amended, but only by a two-thirds 

 majority; and amendment is not within the compet- 

 ence of any particular union concerned. "Once an 

 international union is established," says Sir Arthur 

 Schuster, "it become autonomous" except "in a few 

 matters in which a common pohcy is desirable." He 

 might perhaps have added, that these "few matters " 

 include the one and only matter about which there is 

 any difference of opinion ; and that, so far as co- 

 operation with "enemy" countries is concerned, any 

 science which contents to form a union loses its 

 autonomy completely. Einstein may attend a congress 

 of physics after 193 1 if more than two-thirds, not of 

 the physicists of the world, but of the members of 

 the council, consider it advisable to allow him. 



I have some experience of the working of the 

 statutes myself, for I was a member of the committee 

 appointed to consider the formation of a Union of 

 Mathematics. When this committee met I moved, 

 on behalf of the society of which I was a representa- 

 tive, that it was desirable " that any union which 

 should be formed should be thrown open to the mathe- 

 maticians of all nations at the earliest practicable 

 opportunity." This resolution was rejected, not on 

 the ground that it did not represent the general opinion 

 of mathematicians (as beyond doubt it did), but on the 

 ground that it conflicted with the statutes of the 

 council. 



The object of this council is not to promote inter- 

 national co-operation, but to exclude the Germans 

 from it. I do not know who wrote the article in the 

 Times of which Sir Arthur Schuster complains, nor 

 have I any direct information as to the decisions of 

 English biologists; but if indeed they have refused 

 to join on the ground that the formation of a union 

 " would perpetuate differences which should be left to 

 time to heal," then they deserve the thanks of every 

 English man of science ; and so, too, does the corre- 

 spondent of the Times, who has blurted out what so 

 many of us have been feeling and so few have had the 

 courage or the energy to say. G. H. Hardy. 



New College, Oxford, March 21. 



Solar Radiation in Relation to Faculae. 



In my letter published in Nature of January 13, 

 p. 630, it was suggested that the apparent relation 

 between increased solar radiation and sun-spots was 

 due to outbursts of heated gases accompanying the 

 spots. This conclusion seems confirmed by later 

 observations furnished from the Observatory of La 

 Plata by Mr. Bernhard H. Dawson. 



Since September there have been eleven cases in 

 which outbursts of faculae were observed on the east 

 edffe of the sun, and eight in which they were 

 observed on the west edge. The accompanying table 

 shows the mean values of solar radiation preceding 

 and following the appearance of these faculae. Zero 

 dav indicates the day of observation and the numbers 

 are the amounts exceeding 1-900 calories per sq. cm. 

 per minute. 



Faculae on East Limb of Sun. 



Before Days after 



I o I 2 3 4 5 6 7 8 9 10 n 12 13 14 

 Solar radiation 38 60 42 38 52 49 49 54 49 50 50 44 56 60 59 51 



These results show a marked maximum of solar 

 radiation on the day of observation whether the 

 faculae were on the east limb or the west limb. After 

 their appearance on the east limb there was a second 

 maximum twelve days later, and there was also a 

 maximum ten to eleven days preceding the observa- 

 tion of faculae on the west limb. 



The results are plotted in the accompanying 

 diagram (Fig. i). It would seem from these results 



1.960 - - 



Faculae on West Lim,l) of Sun. 



Days be ore 



13 12 II 10 9 8 7 6 5 

 Solar radiation 58 44 56 58 49 56 56 56 53 



NO. 2682, VOL. 107] 



After 



51 46 54 62 



1.950- 



Fig. 



that outbreaks of heated gases on the edge of the 

 sun result in increasing the effective radiative surface 

 of the sun, and thus intensify the solar radiation. 



H. H. Clayton. 

 Buenos Aires, February 19. 



The Sound of Distant Gun-fire. 



Father Schaffers's letter in Nature of March 10 

 on the audibility of gun-fire sounds when travelling 

 through air prompts me to ask if observations have 

 ever been made upon such sound-waves when passing 

 through the earth's crust. In 1917 I commenced 

 to dig gravel in my garden here. The pit finally 

 reached a depth of 12 ft., and was about 7 ft. long 

 by 6 ft. wide. When I had reached a depth of about 

 6 ft., and from that point downwards, I constantly 

 heard the sounds of gun-fire, while at the surface 

 they were quite inaudible. The digging out of gravel 

 was carried on at intervals during a period of many 

 months, and I must have heard the sounds dozens 

 of times. C. Carus-Wilson. 



Strawberrv Hill. 



Many observations similar to the interesting one 

 recorded by Mr. Carus-Wilson were made during the 

 war. The sounds of gun-fire were heard plainly. in 

 excavations, though they were inaudible on the 

 ground above. They were even heard by persons 

 lying with their heads on the ground, but not when 

 sitting up. Mallet remarks that the noise of the 

 firing at the Battle of Jena in 1806 was heard as a 

 low murmur in the fields about Dresden, at a dis- 

 tance of 92 miles, but he adds that " it is almost 

 certain that in this case the noise was transmitted 

 through the earth " (Brit. Assoc. Rep., 1851, p. 283). 

 Grouchy and his officers at Sart-les-Walhain are said 

 to have heard the firing at Waterloo. They "placed 

 their ears to the ground and thus detected plainly the 

 muffled boom of distant guns." 



Charles Davison. 



"Dunster," Cavendish Avenue, 

 Cambridge. 



