March 9, 1922] 



NA TURE 



307 



criticised by his enemies for things which were de- 

 serving of highest praise and especially praised by 

 his friends for things which were unfortunate lapses 

 from scientific accuracy. I should consider it both 

 unwise and imfair to him to specially rest his reputa- 

 tion in aerodynamics upon the so-called Langley Law, 

 or upon the computation which gave rise to it, as 

 they do not seem to represent his best work. The 

 particular computations which led him to enunciate 

 this law are found on pages 63-67, ' Experiments in 

 Aerodynamics.' A careful reading shows that he 

 never actually tried the experiments of which he 

 professed to give the result. ... It is clear from the 

 Doctor's statement that he never demonstrated by 

 direct experiment that weight could be carried at 

 the rate of 200 pounds per horse-power at 20 meters 

 per second, nor that the power consumed decreased 

 with increase of speed up to some remote limit not 

 attained in experiment. He merely assumed that 

 he could have done it by varying the experiments a 

 trifle and based the so-called Langley Law on this 

 mistaken assumption." 



The Regents of the Smithsonian Institution adopted 

 this suggestion and the Langley Law was not inscribed 

 on the tablet. 



The article in Nature of November 3 states that 

 " the Wright Brothers are equally clear in their 

 acknowledgment of Langley 's work," and gives a 

 quotation from them to support this idea. This 

 quotation, taken in connection with the suggestion 

 of the writer in Nature, may have carried to some 

 readers the erroneous impression that the Wright 

 Brothers acknowledged an indebtness to Langley for 

 his scientific work. This was not the fact. The 

 quotation given makes no reference whatever to 

 Langley 's scientific work. It is simply a generous 

 acknowledgment by the Wrights at the time of 

 Langley 's death for the inspiration received from his 

 faith in the possibility of human flight, and contain- 

 ing an expression of gratitude for information as 

 to books on the subject of flight other than those 

 they had already read. The Wright Brothers have 

 also acknowledged their indebtedness to Chanute, 

 Mouillard and others, but have always made it clear 

 that tlieir greatest debt was to Lilienthal. 



k Griffith Brewer. 



33 Chancery Lane, London, W.C.2. 

 Some difficulty is felt in continuing a discussion of 

 the relative merits of the great pioneers in aviation, 

 Prof. Langley and the Wright Brothers, since they 

 are all entitled to our esteem, and comparison seems 

 to be unnecessary. Mr. Griffith Brewer does not 

 appear to dissent from such a general statement, but 

 one suspects that his enthusiastic admiration for the 

 work of the Wright Brothers has led him to make 

 extravagant claims. 



It is very surprising to hear that " the Wright 

 Brothers first established a scientific basis for aero- 

 plane design," and that their laboratory measure- 

 ments " covered a field many times greater than had 

 been covered by the work of all other experimenters 

 together." The only publication cited in support 

 of this contention occurs in two pages of the Century 

 Magazine in 1908, and readers of scientific literature 

 in aeronautics will realise that they do not know 

 where to look for data based on the work of the 

 Wright Brothers. Indeed, Mr. Brewer indicates that 

 this must be so when he says, " While in Dayton (in 

 1914) I was allowed to examine, with the privilege 

 of copying, much of the personal correspondence and 

 diaries, as well as the records of the early puiely 

 scientific work of the Wright Brothers " ; apparently 



NO. 2732, VOL. 109] 



the work was not publicly available. Is it then 

 strange that one should look to Langley as the 

 scientific pioneer, since he took the normal steps of a 

 man of science and pubUshed complete accounts of 

 his results as he obtained them ? 



Mr. Brewer refers to the " Langley Law " that the 

 faster an aeroplane be flown the less will be the power 

 required to sustain it. He says: "The fallacy of 

 this law is well known to all aeronautical engineers 

 to-day, but up to 1910 this was generally accepted 

 as Langley 's chief contiibution to the science of 

 aerodynamics." The inadequacy of the law is 

 evident now, but it is still at least partly true ; in 

 the case of the most modem aeroplanes the horse- 

 power for flight decreases as the speed increases from 

 the least at which support can be obtained. The 

 increase of power required to increase the speed of 

 the modem aeroplane above a certain limit is due to 

 the light-weight engine, a factor which did not come 

 into consideration in early practice. The error of 

 unsound extrapolation outside the experience of the 

 day was made, but only superficial observers could 

 regard the enunciation of the law as " Langley 's 

 chief contribution " to aeronautical research. 



One can only disagree with Mr. Brewer in his review 

 of the situation and regret that this aspect of pioneer 

 work in aviation was introduced in the tone of the 

 paper on ' ' The Langley Machine and the Hammonds- 

 port Trials." The point of the paper was not so 

 rnuch missed, as suggested by Mr. Brewer, as countered 

 owing to the fact that the statements therein did 

 not carry conviction. One of the articles in Nature 

 intimated this in the suggestion that the Royal 

 Aeronautical Society should take up the matter and 

 after full investigation issue an official report. The 

 views on the Langley aeroplane expressed by Mi. 

 Brewer cannot be accepted as final although given 

 in all good faith. 



The Writer of the Articles. 



Some Biological Problems. 



Dr. Cunningham (Nature, February 9, p. 173) 

 cannot be more weary of this discussion than I. It 

 is many years since I, becoming doubtful, first tried 

 to discover the precise meaning of certain biological 

 key-words. To this daj'^ I have not succeeded. It has 

 been my misfortune to encounter authoritative people 

 who, instead of perceiving that I was genuinely 

 puzzled, thought I might do " much harm by leading 

 many who have no special knowledge of heredity and 

 evolution " — e.g. Professors Goodrich and Bayliss — 

 " to distrust the work of those who are engaged in 

 research on these subjects." May I suggest that in 

 this matter authority and regard for public opinion 

 are out of place. Most biologists profess to know 

 the meanings of their terms ; but there is no agree- 

 ment, and no definitions can be framed which cover 

 the whole of common and accepted usage. A science 

 which lacks a precise and significant means of expres- 

 sion labours under paralysing difiiculties. 



Dr. Ruggles Gates thinks that a variation is a 

 character. Surely he is mistaken. When one in- 

 dividual varies from another [e.g. child from parent) 

 the difference is revealed in a character. If this new 

 character becomes established in the species, it re- 

 mains a character ; but, even colloquially, it ceases 

 to be a variation. How then can a variation be a 

 cliaracter ? A variation cannot be thought of without 

 a comparison, explicit or implicit, between two sep- 

 arate individuals ; a character can always be thought 

 of without such comparison. Evidently, then, a varia- 

 tion is not a character, but an unlikeness between two 

 individuals which is displayed in a character. When we 



