October 14, 1915] 



NATURE 



^1^ 



Distances at which Sounds of Heavy Gun-firing are 

 Heard. 



In Nature of September 30 1 see a letter from 



r. Henry de Varigny on the above subject. It re- 



inds me of September 2 last year, when I noted 



my diary: — "The day here (400 ft. elevation on 



arp of the Lower Greensand overlooking- the Weald) 



IS brilliantly fine and warm, without a cloud, South 



Dwns misty, a gentle wind from the south-eastward. 



y sistdr heard very distant continuous rumbling, 



[« guns, all the morning up to 1.30, and several 



nes mentioned it when sitting in the garden ; my 



achman and a maid-servant also heard it. What 



IS going on that day in France it would be interest- 



g to know ; there was no gun-firing on the coast of 



issex." I wrote, after taking bearing on map : — 



[t may possibly be as far as 150 miles to Amiens." 



find twice since, and only a fortnight ago, similar 



continuous rumbling has been heard, but unfortunately 



the date not noted. I am much too deaf to hear such 



ds myself. H. H. Godwin-Austen. 



re, Godalming, October i. 



The only papers on this subject with which I am 

 Kuuninted are the following: — (i) The distance to 

 h the firing of heavy guns is heard. Nature, vol. 

 . 1900, pp. 377;79; (2) the audibility of the minute- 

 guns fired at Spithead on February' i. Knowledge, 

 vol. xxiv., 1901, pp. 124-25. Reference might also be 

 made to Nature, vol. xli., 1890, p. 369, and vol. Ix., 

 , p. 139. The firing during the funeral procession 

 -o late Queen Victoria was heard to a distance of 

 ... miles from Spithead. There is therefore no reason 

 wliy firing along the Belgian coast should not, with 

 fa'.ouring winds, be heard for many miles inland 

 ! our coasts. The air-vibrations affect pheasants 

 other birds (probably by swaying the branches of 

 -I for some distance after they cease to be per- 

 CL[)iible to the human ear, as was widely observed 

 on the occasion of the North Sea battle on January 24. 

 ' uld suggest that observations of this kind should 

 i)e forwarded to Dr. de Varigny. 

 nay add that the literature relating to explosions 

 're extensive and much more valuable than the 

 Prof. Omori's memoirs on the eruptions of the 

 iia-yama (Bull. Imp. Earthquake Inves. Com., 

 1' icyo, vol. vi., 1912, pp. 1-147, and vol. vii., 1914, 

 nt' 1-2 15) contain many interesting observations. A 

 rases of recent explosions in factories are noticed 

 \ture, vol. Ixi., 1899, PP- Qi-02. and Kuowledge, 

 i.. 1904, pp. 94-95. Mr. S. Fujiwhara has lately 

 published a valuable memoir on the abnormal pro- 

 pairntion of sound in the atmosphere (Bull, of the 

 '^ ■ T. Meteor. Obs. of Japan, vol. ii., pp. 1-143). 

 contains a mathematical discussion of the problem, 

 special reference to the observations recorded by 

 Omori. References to recent German literature 

 10 subject are also to be found in this memoir. 

 Charles Davison. 

 Manor Road, Birmingham. 



The late Prof. E. A. Minchin on "The Evolution of 

 the Cell." 



I'K'or. E. .\. Minchin was looking forward with 

 St at the time of his death to distributing the 



I a prints " of his Manchester address, which was 

 times as long as will appear in Nature. These 



ras" are now in my possession, but I have no 



ns of getting Prof. Minchin's "list." I shall be 

 happy to send a copy to anyone who will send 



I postcard asking for it. 



Edward Heron-.\llen. 



uge .\cres, Selsey Bill, Sussex. October 12. 



NO. 2398. VOL. 96] 



DEATH FROM STATIC CHANGES IN 

 ATMOSPHERIC PRESSURE. 

 A S mentioned in a note in Nature of July S 

 ^^ (p. 515), M. R. Arnoux has found that a 

 momentary diminution of at least 350 mm. of 

 mercury in barometric pressure may be produced 

 within three metres of a bursting high-explosive 

 shell; and he suggests that the sudden diminution 

 of pressure may cause death by the liberation of 

 gas-bubbles in the blood, and consequent blocking 

 of the circulation. 



In his book on "La Pression Barometrique," 

 published nearly forty years ago, Paul Bert 

 proved that the various symptoms which often 

 follow decompression from high atmospheric 

 pressure are due to liberation of gas-bubbles in 

 the blood or tissues. In diving work, and various 

 kinds of engineering work under water or in 

 water-bearing strata, men are exposed to high 

 atmospheric pressure. During the exposure the 

 blood passing through the lungs takes up in 

 simple solution an extra amount of gas in pro- 

 portion to the increased partial pressure of each 

 gas present in the lung air. The gases present 

 are oxygen, carbon dioxide, and nitrogen. The 

 extra free oxygen taken up is, however, very 

 small in amount as compared with the total free 

 and combined oxygen taken up at normal atmo- 

 spheric pressure ; and since much of this total 

 is used up as the blood passes through the tissues, 

 there is no appreciable rise in the very low partial 

 pressure of oxygen in the blood of the systemic 

 capillaries or veins or in the tissues. There is 

 also no rise in the low partial pressure of carbon 

 dioxide in the lung air or blood, since the breathing 

 is so regulated as to maintain a practically con- 

 stant partial pressure of carbon dioxide in the 

 lung air. On the other hand, the partial pressure 

 of nitrogen in the blood leaving the lungs rises 

 in proportion to the increased atmospheric 

 pressure, and as no free nitrogen is used up, 

 every part of the body becomes gradually satu- 

 rated with nitrogen at this increased partial 

 pressure. If, now, the atmospheric pressure is 

 again reduced to normal, the blood and semi- 

 liquid tissues of the body are left in a condition 

 of super-saturation with nitrogen, and as a con- 

 sequence bubbles, consisting almost entirely of 

 nitrogen, are apt to form, and to cause very 

 serious effects. Death may result from blockage 

 of the circulation through the lungs or heart- 

 muscle ; paralytic attacks may be caused by 

 blockage in the brain or spinal cord ; while char- 

 acteristic localised pain (so-called "bends") may 

 be produced by the presence of bubbles elsewhere. 



It is clear that if the atmospheric pressure is 

 considerably diminished from normal, a similar 

 condition of super-saturation of the body with 

 nitrogen will exist, so that bubbles may be 

 formed; and it is natural to suspect that a sudden, 

 though only momentary, diminution, due to the 

 bursting of a shell, might liberate bubbles. There 

 are, however, facts which tell strongly against 

 this hypothesis. 



In the first place, it must be pointed out that 



