August 17, 19 16] 



NATURE 



509 



on his wheat, that has inspired the German farmer to 

 greater efforts during the last ten years. The need 

 for well-educated men as managers of estates is more 

 commonly recognised in Germany than in England ; 

 hence a career is open to successful students from the 

 training institutions of Prussia, while the English 

 student who lacks the capital to farm on his own 

 account must look abroad for an outlet for his know- 

 ledge of practical agriculture. 



Mr. Middleton believes that our system of education, 

 though starting thirty years behind that of Germany, 

 mainly wants time to grow. It is unfortunate that it 

 had only just started before the war and that results 

 will be sought at a time when patience will be neces- 

 sar\' but very difficult to exercise. The chief imme- 

 diate cause of the increased productivity of German soil 

 is the increase in the use of artificial manures. The 

 German farmer is no more skilful than the British, 

 but his natural obedience to authority leads him to 

 apply artificial manures in such quantities as his in- 

 structors, relying on the systematic work of the ex- 

 periment stations, may from time to time direct. 

 Twice as much nitrogen, one-third more phosphate, 

 and five times as much potash are used in Germany 

 as on an equal area of our cultivated land.' As regards 

 the two former manures, we import nearly three tons 

 more feeding stuffs per one hundred acres than the 

 Germans, and this should balance to some extent the 

 smaller amounts of nitrogen and phosphate applied 

 direct to the soil ; but careless storage of farmyard 

 manure results in the loss of some 50 per cent, of the 

 nitrogen and a good deal of the phosphate, so that far 

 less than the theoretical amount ever gets to the grow- 

 ing crop. Germany is fortunate in that she has not 

 only immense deposits of potash salts, but also vast 

 i areas of light soils able to give abundant returns from 

 I these manures when skilfully applied. This combina- 

 I tion plays an important part in the recent progress of 

 1 German farming. 



IHE ROYAL AIRCRAFT FACTORY 

 INQUIRY. 



npHE whole question of the Royal Aircraft Factory 

 ■■■ administration and cost seems to turn on 

 i whether it is to be regarded as an experimental or a 

 j productive concern. If it is to be regarded as a fac- 

 I tor}- for the production of service machines, then there 

 ' is little doubt that it is not administered as efficiently 

 as it might be. But if it is to be regarded as a purely, 

 I or at least chiefly, experimental establishment, then 

 1 the case is completely altered. In the development of 

 I a new industry, such as aeronautics, there must be 

 I a certain amount of experiment, and in modem times 

 I the tendency is to arrive at a satisfactory result by 

 the application of science to the fullest possible extent, 

 ; rather than to attain that result by a lengthy process 

 , of trial and error. The inevitable result of the scien- 

 tific method is that it appears as though a consider- 

 able amount of money is being wasted with no appre- 

 I ciable result, but in reality the money is being well 

 ; spent if it leads to scientific results of a widely useful 

 I nature. The Royal Aircraft Facton,- should therefore 

 be judged by its achievements in the advance of aero- 

 : nautical science rather than by its actual output of 

 i machines for service use. There can be no doubt at 

 I all that the work done at the factory, in conjunction 

 ' vyith the model experiments and mathematical inves- 

 tigations at the National Physical Laboratory, has 

 I elucidated many questions of vast importance concern- 

 ing the design and stabilit}' of aeroplanes in a way 

 I which would perhaps never have been done by private 

 j firms, where output is the primary consideration. 

 ' Once it is admitted that this scientific information 

 XO. 2442, VOL. 



97] 



is needed, the Royal Aircraft Factory stands justified 

 by its past work. By all means reorganise, if by such 

 reorganisation increased efficiency can be obtained, 

 but let it not be at the expense of the exceedingly 

 valuable experimental work which is being done, and 

 which can be done in no other way at the present 

 time. 



It is often argued that private firms can produce 

 machines equal to those of the Factory, without spend- 

 ing so much time and money on the experimental side. 

 This is by no means true, since the results of such 

 experimental work at the Factor^' and elsewhere have 

 always been available to a large extent to any who 

 cared to avail themselves of them, and many good points 

 in proprietary machines are indirectly due to this fact. 

 There is still an inclination on the part of some firms 

 to view the scientific side of the subject with suspicion, 

 and even to depreciate experimental aeronautics alto- 

 gether, but surely the sooner experimental results be- 

 come more widely known the better it will be for the 

 future development of the aeronautical industry. In 

 the provision of these scientific fundamentals of aero- 

 nautics the Royal Aircraft Factory has played, and is 

 playing, an important part, and any attempt at re- 

 organisation which would impair its utility as an 

 experimental establishment, and reduce it to the level 

 of a productive factory for existing designs, would be 

 a great mistake at the present early stage of aero- 

 nautical development. 



LORD KELVIN AND TERRESTRIAL 

 MAGNETISM.^ 

 T IKE most branches of physics, terrestrial mag- 

 ^-^ netism has associations w^ith the name of Kelvin, 

 and, characteristically enough, these associations are 

 at the two confines of the subject, the immediately 

 practical, and the speculative. Lord Kelvin, I need 

 scarcely remind you, introduced important changes of 

 design into compasses, and the construction of com- 

 passes was an important object of the Glasgow firm 

 which eventually bore his name. 



The other point of contact between Lord Kelvin and 

 terrestrial magnetism, as already mentioned, relates to 

 theory. All here know that there occur from time to 

 time phenomena known as magnetic storms, during 

 which there are difficulties in carrv'ing on ordinarv 

 telegraphy. There has long been a belief that the sun 

 is the principal, if not the only, source of magnetic 

 storms, and of the less striking regular changes every 

 day visible. Lord Kelvin directed attention to the 

 difficulties in the way of accepting any sensible direct 

 magnetic action between the sun and the earth. His 

 earliest remarks on the subject, to which I shall refer, 

 are contained in a short note on p. 154 of vol. iv. of 

 his "Mathematical and Physical Papers." "The 

 sun's magnetisation," he said, "would . . . need to 

 be 120 times as intense as the earth's to produce a 

 disturbance of i' in declination even by a complete 

 reversal in the most favourable circumstances." 



The much later communication, to which I ne.xt 

 refer, was made in 1892 to the Royal Society, on an 

 occasion — a presidential address — when original con- 

 tributions to science are unusual. Lord Kelvin, how- 

 ever, devoted fully half his address to terrestrial mag- 

 netism. After referring to various solar and terrestrial 

 magnetic phenomena he adds (loc. cit., p. 307) : — "But 

 now let us consider . . . the work which must be 

 done at the sun to produce a terrestrial magnetic 

 storm." He then quotes from a paper by the late 

 Prof. W. G. Adams data relating to a magnetic storm 

 of June 25, 1885, and proceeds :—" To produce such 

 changes as these by any possible dynamical actioa 



i Abridged from the Seventh Ketvin Lecture delivered be/br» the Instita 

 tion of Electrical Engineers on February 17, by Dr. C. Chree, F.R.S. 



