June 22, 1911J 



NATURE 



557 



failure of the writers to take account of sufficient data, 

 and in particular to appreciate the interdependence of 

 the equations of motion, and this is the less easy to 

 understand as this interdependence in the case of 

 lateral stability is clearly pointed out in Lanchester's 

 " Aerodonetics." 



The report on electrification of balloons is followed 

 by brief accounts of experiments by Messrs. G. W. 

 Walker and W. Makower. The subject is an impor- 

 tant one, the neglect of which may be responsible for 

 at least one serious dirigible fatality in Germany. 

 Rear-Admiral Bacon gives a translation and abstract 

 of the programmes of the German Society for the 

 Study of Airships. 



Passing, however, to the articles dealing with "re- 

 searches," we find voluminous descriptions of apparatus 

 and diagrams of experimental details, none too easy 

 to follow, which may well suggest to the uninitiated 

 reader to ask, " What has all this to do with 

 aeronautics?" A doubt may readily arise as to 

 whether the structural details of a wind tower, experi- 

 ments on a lish-shaped body moving in water, or a 

 diagram showing the weather conditions prevailing 

 on a certain day at Portsmouth or Berwick will in any 

 way reduce the record of a score of people killed, 

 besides those wounded by accidents during the first 

 fcur months of the present year. The inclusion of 

 unnecessary minutiae will only tend to strengthen the 

 violent attacks which were made recently on the work 

 of the committee by a well-known motorist writing 

 in a popular magazine. The writer in question took 

 up the well-known "practical" attitude, and sug- 

 gested that if the Government wanted to do any good 

 they should buy a commercial aeroplane; they should 

 keep their committee muzzled (so to speak), and should 

 only consult them when the machine got out of order, 

 in which case they should be expected to rectify the 

 mischief, presumably, at a few hours' notice. This, 

 according to the writer, was the condition under which 

 experts in English commercial firms labour, and he 

 was shocked at the idea of a Government committee 

 having any free will as to what they were to do. 



It is hardly necessary to point out in Nature that 

 no body of scientific men would consent to serve on a 

 committee under conditions so detrimental to efficiency, 

 or to direct attention to the waste of money which 

 occurs when experts are called on to patch up defects 

 which, under more favourable conditions, they could 

 have anticipated previously. But it does appear that 

 the bearing of many of these researches on aerial navi- 

 gation has been considerably obscured by the inclusion 

 of unnecessary matter which would have been better 

 filed for future reference instead of being published. 



At the present time, apart from stability and the con- 

 struction of light motors, the most important problem 

 of aerial navigation is the behaviour of aeroplanes and 

 dirigibles in gusty winds, the determination of the 

 maximum fluctuations, of the stresses these set up in 

 the various surfaces and frameworks, and of the 

 changes of motion they produce, and whether these 

 involve loss of control. Now Dr. W. N. Shaw, F.R.S., 

 of the Meteorological Office, has drawn up a report 

 of about sixteen pages on " Details of Wind Structure," 

 in which he states at the beginning, " In drawing up 

 this statement, endeavour has been made to summarise 

 briefly. Additional details can be supplied in further 

 illustration if required." After the concise and lucid 

 exposition which the author gives, it is rather a striking 

 contrast to find more than forty sheets of diagram- 

 matic details of records taken at particular places. 

 These greatlv increase the bulk of the volume, and 

 in view of the previous work by Langley on "The 

 Internal Work of the Wind." the provisions stated on 

 p. 10 for enabling the records to be consulted might 



NO. 2173, VOL. 86] 



well have been utilised to save the cost of printing 

 all these diagrams. Moreover, the scale of time is too 

 small to show the intervals between the gusts, a detail 

 of some importance. 



The sections dealing with the measurement of pres- 

 sures also contain a profusion of diagrams and mechan- 

 ical details of a purely subsidiary character, and the 

 general conclusions are not well stated. A good deal 

 of space is taken up with the details of experiments 

 in water, which would find a more natural place in 

 the transactions of the Institution of Naval Architects 

 than in a report on aeronautics. 



The splendid equipment of the National Physical 

 Laboratory at Teddington is described in six pages of 

 letterpress by Dr. T. E. Stanton, but here again the 

 diagrams are unnecessarily large and bulky, and a 

 more useful purpose would have been served if these 

 had been reduced, and the space used for a fuller 

 exposition of the bearing of the experiments on aerial 

 locomotion. 



We notice that for experiments on the pressure on 

 planes the use of a whirling table is not considered 

 satisfactory, and that a wind tunnel has been preferred 

 for the purpose. The main objection to this plan is 

 that no attempts have been made so far to investigate 

 the pressure distribution on a plate which has a move- 

 ment of rotation as well as of translation. The results 

 therefore can only apply to an aeroplane driven steadily 

 through calm air, since when either free or forced 

 oscillations take place rotation plays an important part 

 in them. The experimental determination of these 

 rotational effects will necessarily be difficult, and a 

 whirling table suggests a possible method ; at the same 

 time results possessing even a very rough degree of 

 accuracy are better than no results at all, and their 

 absence limits the systematic investigation of aeroplane 

 motions to machines the supporting surfaces of which 

 are narrow. No reference to rotating planes is made 

 in the programme of the committee. 



If the committee instead of confining its attention 

 to ideal surfaces, had discussed the application of 

 its conclusions to the successful types of aeroplane 

 and dirigible of the present day, the report would 

 have better corresponded with its title. 



The interim report on the Motor Prize Competition 

 offered by Mr. P. Y. Alexander in 1909, which 

 took place last July, exhibits the same features as 

 the other reports. It contains details and diagrams 

 of the friction dynamometers used for testing the 

 motors, particulars as to the mode of estimating the 

 weight of the latter, the quality and price of the 

 petrol, the insurance of the maker's servants for 

 employer's liability, the number of representatives 

 allowed to be present at the tests, the temperature 

 of the room, the times of day at which two pints of 

 water were added to the radiators, and other details 

 carried to the same degree of elaborateness; in short, 

 everything except a statement of tlie general conclu- 

 sions of a scientific character to be derived from the 

 tests, as apart from mere statistics. 



Sir George Greenhill's report is essentially a mathe- 

 matical treatise on discontinuous motion, covering all 

 the problems which have up to the present been 

 solved. An important improvement has been made on 

 the treatment given in the earlier text-books, by the 

 introduction of constants. Old students of hydro- 

 dynamics will remember a difficulty that suggested 

 itself arising from the fact that a solution might 

 apply to a stream flowing past a lamina of breadth » 

 with velocity i, but it was not obvious what could 

 bo done if the breadth of the lamina were a and the 

 velocity v. This treatise will be of great use to 

 workers in our universities who are seeking to extend 

 the applications of pure mathematics to physical 



