September 8, 192 1] 



NATURE 



61 



interests, and to develop a sense of comradeship 

 and co-operation, and this can be done only if we 

 are all made free of the company — if our musical 

 education is such that we can meet each other as 

 frankly and openly in this field as educated men 

 are accustomed to do in the discussion of science 

 or poetry. 



Agricultural Economics. 



The address of Mr. C. S, Orwin to Section M 

 (Agriculture) deals with the importance of 

 the study of ag^ricultural economics. It points 

 out the overriding- influence of the economic factor 

 in all matters affecting the management and de- 

 velopment of land. Soil, climate, and other factors 

 have their importance, but the farmer can grow 

 anything if there is a market for it, and his main 

 consideration must be in all cases, not what will 

 the land grow, but what can he sell at a profit to 

 himself. Examples are given to illustrate the rela- 

 tively small importance of soils and climate in crop 

 production and the dominating influence of the 

 market in combination with transport facilities. 



Attention is also directed to the need for econ- 

 omic study in the organisation of farm manage- 

 ment so as to prevent the wasteful application of 

 one or more of the factors of production : land, 

 capital, and labour. Thus a small farm may be 

 made highly productive by a prodigal use of 

 manual labour, but the same amount of labour 

 applied to a larger area of land in conjunction with 

 a bigger capital outlay on machinery equipment 

 will increase the output per man employed, and 

 it is suggested that production can be directed 

 scientifically and to the general advantage only by 

 a study of the three factors so as to use them in 

 proper relation to each other. 



The address aims at directing attention to the 

 fact that the scientific research work in agricul- 

 ture, which was first inaugurated publicly about 

 twenty-five years ago, has taken no account of the 

 need for the study of agricultural economics, and 

 that agricultural research can never bear its proper 

 fruit until investigations conducted along the lines 

 1 of natural science are balanced by research work 

 on an equal scale in agricultural economics. 



Science and Citizenship. 

 Sir Richard Gregory's "Message of Science," 

 I delivered to the Conference of Delegates of Corre- 



I sponding Societies, is a plea for closer associa- 

 tion between scientific workers and the rest of the 



! community, as a means of promoting social well- 



I* being. 



Civilised man has proved himself unworthy of 

 the gifts which science has placed at his disposal, 

 with the result that squalid surroundings and 

 squandered life are the characteristics of modern 



; Western civilisation instead of social conditions 

 and ethical ideals superior to those of any other 

 epoch. Responsibility for this does not lie with 

 scientific discoverers, but with statesmen and 

 democracy. Like the gifts of God, those of 

 science can be made either a blessing or a curse, 

 to glorify the human race or to destroy it; and 



I upon civilised man rests the decision as to the 



I course to follow. With science as an alh % and 

 the citadels of ignorance and self as the objective, 

 he can transform the earth ; but if he neglects 

 the guidance which knowledge can give, and pre- 

 fers to accept the phrases of rhetoricians, this 

 world will become a place of dust and ashes. 



Unsatisfactory social conditions are not a neces- 

 sary consequence of the advance of science, but 

 of incapacity to use it rightly. Whatever may 

 be said of captains of industry and princes of 

 commerce, men of science cannot be accused of 

 amassing riches at the expense of labour, or of 

 having neglected to put into force the laws of 

 healthy social life. Power — financial and political 

 ^has been in the hands of people who know 

 nothing of science, not even that of man himself, 

 and it is they who should be arraigned at the bar 

 of public justice for their failure to use for the 

 welfare of all the scientific knowledge offered to 

 all- Science should dissociate itself entirely from 

 those who have thus abused its favours, and not 

 permit the public to believe it is the emblem of 

 all that is gross and material and destructive in 

 modern civilisation. It is the pituitary body of 

 the social organism, and without it there can be 

 no healthy growth, mentally or physically. 



The Conference of Delegates provides an appro- 

 priate platform for this message of exhortation. 

 There are now 130 Corresponding Societies of the 

 Association, with a total membership of about 

 52,000, and their representatives should every 

 year go back, not only strong with zeal for new- 

 knowledge, but also as ministers filled with the 

 sense of duty to inspire others to trust in it. 



The Present Position of the Wave Theory of Light.^ 

 Bv Dr. R. a. Houstoun. 



II. 

 AVTE come now to the fundamental difficulties. 

 They have been stated very clearly by 

 Dr. G. W. C. Kaye in his book on X-rays, and 

 we shall borrow his method of presenting them :— 

 (i) When X-rays encounter a gas, only an ex- 

 ceedingly small fraction of its molecules becomes 

 ionised. 



1 Continued from p. 15. 

 NO. 2706, VOL. 108] 



(2) The extent of this ionisation is unaffected 

 by temperature. 



(3) \Vhen X-rays encounter a metal, the cor- 

 puscles ejected have a velocity which 



(a) does not depend on the intensity of the X- 

 rays, and so is independent of the distance of the 

 metal from the X-ray bulb; 



(b) increases continuously with the hardness, 

 i.e. frequency, of the X-rays; 



