i88 



NATURE 



[M. 



iQi; 



from any questions as to how best to deal with 

 the gust problem, the study of the forced 

 oscillations of an aeroplane is a problem pro- 

 posed for solution many years ago, which has 

 to be solved sooner or later in the development of 

 the aeroplane, and the sooner the better. Of course, 

 the treatment is limited to the consideration of 

 small disturbances, 'but we believe it was Mr. 

 Bairstow who, in the earlier days of his experi- 

 ments, pointed out that a theory so formed might 

 give useful approximations for practical purposes, 

 just as our knowledge of the pendulum was largely 

 based in the first instance on the study of oscilla- 

 tions of small amplitude. It will be seen that both 

 longitudinal and lateral disturbances are considered, 

 although the inconvenient notation renders it a 

 little difficult to know what is longitudinal and 

 what lateral, or even whether the aeroplane is sup- 

 posed to be flying forwards or backwards. An 

 alternative method of treating gusts has been 

 developed and worked out by Mr. Brodetsky in 

 this country, although only his first paper has yet 

 appeared in print. 



The value of mathematical work of this kind has 

 been called in question by certain meteorologists 

 who have claimed that theirs was the proper 

 method of solving the problems of aviation. A 

 study of the present collection of papers, however, 

 shows that while meteorological investigations are 

 required to ascertain the conditions under which 

 flights are made, it is necessary to resort to very 

 long, hard mathematical calculations in order to 

 ascertain how these conditions can be met in the 

 construction of a flying machine. Of course, work 

 such as that of Prof. Wilson requires developing 

 from the experimental side, but the mathematics 

 must be done previously. G. H. B. 



NOTES. 



The present position of nitrogen fixation in this 

 country was stated in the House of Commons on 

 May 2 by Mr. Kellaway, Parliamentary Secretary to 

 the Ministry of Munitions, in reply to a question by 

 Sir William Beale. The various proposals for fixing 

 nitrogen have been examined in detail by the Nitrogen 

 Products Committee of the Munitions Inventions De- 

 partment, and, as a result, intensive research has 

 been concentrated upon the Haber process. A research 

 staff composed endrely of young British scientific 

 workers has accumulated the knowledge requisite to 

 the translation of the vague outlines of this process 

 of ammonia synthesis, as revealed in the patents of 

 the German industrial concerns, Into a commerciallv 

 practicable process. This has involved two years of 

 unremitting laboratory research, during which period 

 numerous departmental patents have been taken out 

 for improvements in ammonia synthesis, as well as 

 in the subsidiary branches of the problem, such as 

 hydrogen manufacture. These patents are held in 

 the names of the members of the research staff, and 

 are assigned to the Secretary of State for War. The 

 research work of the staff of the Munitions Inventions 

 Department is now far advanced, so that the results 

 have been placed at the disposal of the Explosives 

 Department for application on a factory scale. The 

 manufacturing operations will be conducted at present 

 for war purposes, the production of synthetic ammonia 

 being applicable to the manufacture of explosives, as 

 NO. 2532, VOL. lOl] 



well as to the production of ammonium sulphate for 

 agriculture. The results of the research work on syn- 

 thetic ammonia have not been made public, but may 

 be communicated confidentially to concerns proposing 

 to erect plant under financial arrangements approved 

 by the Treasury. The availability to manufacturers, 

 of the general research work of the staff of the Muni- 

 tions Inventions Department is now being considered 

 by committees representing the several departments 

 concerned. 



The Gas Traction Committee, appointed in Novem- 

 ber last to consider the employment of coal-gas as a 

 substitute for petrol and petroleum pioducts in motors,. 

 its general safety, and conditions lor use, has issued 

 an interim report (H.M. Petroleum Executive, price 

 id.). This deals chiefly with the present use of gas» 

 mainly at low pressures, in suitable fabric bags ; the 

 work is to be continued to cover its use under higher 

 compressions when the necessary appliances and plant 

 are obtainable. The Committee is satisfied that gas can 

 be efficiently, safely, and promptly substituted for motor- 

 spirit (only two minor accidents have been reported). 

 Two hundred and fifty cubic feet are considered equiva- 

 lent to one gallon of petrol, so that gas at 4s. per 

 1000 cub. ft. is equivalent in cost to petrol at is. per 

 gallon. No restrictions, except in so far as the 

 shortage of coal or other war conditions may demand, 

 should be imposed on the vise of gas in suitable con- 

 tainers. A specification for the bags is given ; the 

 material should be two-ply diagonally doubled, and 

 proofed with 6 oz. per square yard of proofing con- 

 taining 90 per cent, of high-class rubber, this being 

 vulcanised by the hot process. The permeability of 

 prepared fabric to hydrogen must not be more than 

 to litres per square metre per twenty-four hours 

 (0-3 cub. ft. per square yard per twenty-four hours). 

 The working life of such containers would normally 

 be eight months. Top ventilation should be provided 

 in any garage, and a container should be completely 

 deflated after standing idle for two weeks. For use 

 under higher compression it is undesirable that semi- 

 rigid containers of rubbered canvas should at present 

 be charged to a greater gas pressure than 90 lb., or 

 be of greater internal diameter than 4 in. Encourage- 

 ment should be given to the construction of semi- 

 rigid containers of rubber and woven wire up to a 

 working pressure of 300 lb., and it is considered desir- 

 able to encourage experiments with rigid metal 

 cylinders working up to 1800 lb., particularly in con- 

 nection with their application to motor-oinnibus use 

 and for the transport departments of municipal' 

 authorities. 



A LETTER to the Press on the subject of food crops 

 and the protection of birds, recently issued by the 

 Royal Society for the Protection of Birds, directs 

 attention to the serious diminution in the numbers of 

 our resident insectivorous birds, due to the severe 

 winter of 19 16-17, and also to the widespread destruc- 

 tion of birds and eggs, which is a cause of grave 

 anxietv at the present time. That everything possible 

 should be done to protect and preserve such species is 

 bevond dispute. As the signatories of this letter point 

 out, all are agreed that insect-eating and vermin- 

 eating species of wild birds are invaluable to man. 

 Further, the farmer and fruit-grower have everything 

 to gain by responding to the present appeal to take 

 the matter up promptly with the view of checking 

 the destruction of these birds and their nests and 

 eggs. Plagues of various species of injurious insects 

 have alreadv been reported from different parts of the 

 country, and but for the services of our resident and 

 migrant insectivorous birds these would each year 

 grow worse. As it is, they already inflict ver^' serious 



