56 



NATURE 



[Septembers, 1921 



army, free from epidemic and communicable 

 disease, from 100,000 men to a million. "Pre- 

 ventive medicine has made it possible to maintain 

 20,000,000 men under arms and abnormally free 

 from disease, and so provided greater scope for 

 the killing activities of the other military weapons. 

 . . . Whilst the surprise effects of chemical war- 

 fare aroused anger as being contrary to riiilitary 

 tradition, they were minute compared with those 

 of preventive medicine. The former slew its thou- 

 sands, whilst the latter slew its millions and is 

 still reaping the harvest." This argument carries 

 no conviction. Poison gas is not merely contrary 

 to European military tradition ; it is repugnant to 

 the right feeling of civilised humanity. It in no 

 wise displaces or supplants existing instruments 

 of war, but creates a new kind of weapon, of 

 limitless power and deadliness. " Mustard gas " 

 may be a comparatively innocuous product as 

 lethal substances go. It certainly was not intended 

 to be such by our enemies. Nor, presumably, 

 were the Allies any more considerate when they 

 retaliated with it. Its effects, indeed, were suffi- 

 ciently terrible to destroy the German moral. The 

 knowledge that the Allies were preparing to em- 

 ploy it to an almost boundless extent was one of 

 the factors that determined our enemies to sue 

 for the armistice. But if poisonous chemicals are 

 henceforth to be regarded as a regular means of 



offence in warfare, is it at all likely that their use 

 will be confined to "mustard gas," or, indeed, to 

 any other of the various substances which were 

 employed up to the date of the armistice? To one. 

 who, after the peace, inquired in Germany con- 

 cerning the German methods of making "mustard 

 gas," the reply was: "Why are you worrying 

 about this when you know perfectly well that this 

 is not the gas we shall use in the next war? " 



I hold no brief for preventive medicine, which is 

 well able to fight its own case. I would only say 

 that it is the legitimate business of preventive 

 medicine to preserve by all known means the 

 health of any body of men, however large or 

 small, committed to its care. It is not to its dis 

 credit if, by knowledge and skill, the numbers so 

 maintained run into millions instead of being 

 limited to thousands. On the other hand, "an 

 educated public opinion" will refuse to give 

 credit to any body of men of science who employ 

 their talents in devising means to develop and 

 perpetuate a mode of warfare which is abhorrent 

 to the higher instincts of humanity. 



This Association, I trust, will set its face against 

 the continued degradation of science in thus aug- 

 menting the horrors of war. It could have no 

 loftier task than to use its great influence in 

 arresting a course which is the very negation of 

 civilisation. 



The British Association at Edinburgh. 



Abstracts of Presidential Addresses. 



THE presidential addresses delivered at a rneet- 

 ing of the British Association are now pub- 

 lished in volume form, thus providing a convenient 

 annual record of authoritative thought and opinion 

 upon a wide range of scientific subjects. The title 

 of the volume just issued is "The Advancement 

 of Sgience, 1921"; the publisher is Mr. John 

 Murray, and the price 65., or to members attend- 

 ing the Edinburgh meeting 45. 6d.' The address 

 of the president of the Association, Sir Edward 

 Thorpe, is also on sale separately, price 15. Fol- 

 lowing our usual custom, we print this address 

 in full in the present issue, and we hope, in suc- 

 ceeding issues, to publish the parts of addresses 

 of presidents of sections of interest to scientific 

 readers generally. The subjects dealt with in 

 these addresses are described in the subjoinea 

 abstracts. 



Problems of Physics. 



In Section A (Mathematics and Physics) Prof. 

 O. W. Richardson will revie^y in his address 

 the present state of a number of lead- 

 ing problems now engaging the attention of 

 physicists. After a brief reference to relativity, 

 the far-reaching importance of the discoveries re- 

 lating to the nature of the nuclei of atoms being 

 made at Cambridge by Sir Ernest Rutherford will 

 first be emphasised. The conditions which govern 

 the emission of electrons by matter will then be 



NO. 2706, VOL. 108] 



considered broadly. This involves a review of the 

 present state of our knowledge of thermionic 

 emission and of photoelectric action. These two 

 groups of phenomena are shown to be very 

 closely, perhaps inseparably, connected. Never- 

 theless, the claim that thermionic emission is 

 merely a manifestation of the photoelectric activity 

 of a body under its own thermal radiation will not 

 withstand a critical examination. The same is true 

 of the wider claim which has been put forward 

 that all chemical action is a similar and immediate 

 effect of radiant activity. There is not, in either 

 case, enough radiation to produce the observed 

 results. The controversy w^hich has lasted more 

 than a century as to the origin of contact potential 

 differences will be referred to, and it will be 

 shown that the new phenomena supply the material 

 required to settle this dispute. All three groups 

 of phenomena are, in fact, closely related, and 

 have undergone similar vicissitudes. In con- 

 clusion, attention will be directed to the rapid 

 unification of light and X-ray phenomena as the 

 result of recent investigations. 



Chemistry and Life. 

 Four years of warfare having given the public 

 some insight into the relation between chemistry 

 and industry,, with perhaps undue stress on 

 utilitarian aspects of the science, it appears desir- 

 able to e^aphasise also the fundamental part played 



