September 13, 1917] 



NATURE 



37 



A valuable paper describing the factors influencing 

 the sex ratio in poultry was read by Dr. Raymond 

 Pearl, of the Maine Agricultural Station. In the pre- 

 sent war conditions any information which would 

 make it possible for the poultryman or farmer to 

 produce a larger number of pullets to lay eggs, with 

 out producing so many cockerels to eat up costly food, 

 would be of very great value. This study, which is 

 based on eight years' experiments and more than 

 :i,ooo individuals, demonstrates, first, that the deter- 

 nination of sex in poultry is primarily a matter of 

 a definite, hereditary mechanism, just as it is in in- 

 sects and other forms which have been studied. At 

 the same time, it is demonstrated, however, that in 

 certain physiological circumstances the operation of 

 this mechanism may be mod,ified in such a way as to 

 lead to the production of more females in proportion 

 10 the number of males. The chief factor in bringing 

 about the modification in the direction of a larger pro- 

 duction of females is the fecundity of laying ability of 

 the hens used as breeders. The larger the number 

 of eggs which a hen lays before being put into the 

 breeding pen, the larger will be the proportion of 

 females and the smaller the proportion of males pro- 

 iced by her eggs. Some yeirs ago it was shown by 

 speaker that the ability to lay eggs (fecundity) in 

 >ultry is a matter of definite Mendelian inheritance. 

 Ls a result of this knowledge, it is possible to breed 

 rains of hens in which productivity is a definitely 

 ted characteristic. The present results, taken in 

 >nnection with the earlier ones, show that when the 

 )ultryman breeds along the right lines for increased 

 fg production, he will at the same time be producing 

 strain in which profit-making pullets preponderate 

 place of the less profitable cockerels. 

 The session on Saturday afternoon (April 14) was set 

 3art for a special symposium on aeronautics, the 

 >eakers including Dr. A. G. Webster, of Clark Uni- 

 rsity, a member of the Naval Advisory Board, and 

 \t. W. F. Durand, chairman of the National Advisory 

 >mmittee for Aeronautics. 

 On Friday evening (April 13) a reception was he'd 

 the hall of the Historical Society of Pennsylvania, 

 ^hen Prof. G. E. Hale, director of the Solar Observa- 

 ry at Mount Wilson, CaHfornia, gave a most in- 

 jresting address on "The Work of the Mount Wilson 

 )bservatory." 



A very pleasant feature of the Saturday afternoon 

 »ssion was the presentation of a portrait of Dr. T. 

 linis Hays, dean of the Wistar Association, by Joseph 

 r. Rosengarten. LL.D., on behalf of the association, 

 the centennial anniversary of its organisation ,_ and 

 the twenty-first year of Dr. Hays's secretaryship of 

 le American Philosophical Society. 



Arthur W. Goodspeed. 



EXPERIMENTAL WORK IN 

 AERONAUTICS.'^ 



THE report to Parliament of the Advisory Com- 

 mittee for Aeronautics for 1916-17 has just been 

 jsued, and is a further vindication of the foresight 

 lown when this committee was inaugurated in 1909 

 inder the presidency of Lord Rayleigh. Since that 

 le funds have been continuously placed at the dis- 

 )sal of the Royal Society for the development of 

 le experimental investigations at the National 

 Physical Laboratory, the aeronautical work of which 

 f?n all its branches is controlled by the Advisory Com- 

 mittee for Aeronautics. 



Although less directly responsible to the Advisory 

 Committee than the National Physical Laboratory, the 



' Report of the Advisory Committee for Aeronautics for the Year 1916-17. 

 (Cd. 8629.) (London : H.M. Stationery Office.) Price irf. net. 



Royal Aircraft Factory carries on its experimental 

 work in close co-operation, as does also the Meteoro- 

 logical Oflice in its aeronautical work. Other institu- 

 tions and private bodies find the Advisory Committee 

 for Aeronautics a suitable body to receive and review 

 their communications. 



In normal times approved reports and papers are 

 collected annually into a technical report issued for 

 sale, but for obvious reasons publication has not taken 

 place since the opening of hostilities. The yolume of 

 material collected is now very large, and special 

 arrangements have been made to render it available 

 to British designers, to whom it is of incalculable 

 value. As the brief report now issued appears to have 

 been framed to give as much information as is pei-- 

 missible and is >f very general interest, it is repro- 

 duced below almost in full. 



NO. 2498, VOL. 100] 



The experimental investigations carried out under 

 the control of the Advisory Committee for Aeronautics 

 into the many problems affecting the development of 

 aircraft have been continued and extended during the 

 past year. 



Owing to the growth of the work of the committee 

 in certain directions, sub-committees have been formed 

 to advise in regard to special matters. An Internal- 

 Combustion Engine Sub-Committee has been appointed 

 under the chairmanship of Dr. Dugald Clerk, while 

 Mr. H. Fowler is chairman of a Light Alloys Sub- 

 Committee. Other sub-committees have been con- 

 stituted from time to time to investigate particular 

 problems. 



Many changes and developments in the design and 

 construction of aircraft have taken place as the result 

 of the continued and varied experience gained from 

 their use in warfare under modern conditions. An 

 increasing number of special problems is thus con- 

 stantly presented for investigation, and these have 

 very closely occupied throughout the year the atten- 

 tion of the staffs engaged in experimental work, both 

 at the National Physical Laboratory and at the Royal 

 Aircraft Factory. In addition to aerodynamical re- 

 search, much attention has been given to questions 

 relating to engines, materials of construction, strength 

 of construction and design, instruments and acces- 

 sories, as well as to methods of attack from aircraft, 

 and other matters. 



Equipment for Experimental Work at the National 

 Physical Laboratory: — Reference was made in the 

 report for last year to the additional equipment pro- 

 vided for experimental work. The wind channels 

 now available comprise two 7-ft. channels, two 4-ft., 

 and one 3-ft. The new 7-ft. channel was completed 

 and brought into use early in the year 1916-17. No 

 important departure has been made in its design 

 from that of the earlier 7-ft. channel, but some rninor 

 modifications have been introduced which experience 

 had indicated as tending to greater convenience in 

 working. An air-speed of 85 ft. per second can be 

 reached in this channel with an expenditure of 160 h.p. 

 It is doubtful whether further increase in size of 

 channel or in speed of air-current would advance 

 existing knowledge to an extent suf!icient to outweigh 

 the greatly increased cost and other disadvantages 

 involved. If it should prove necessary, for certain 

 purposes, to conduct experiments on a larger scale 

 and at higher speeds, it would appear, therefore, to 

 be necessary to employ a method in which the model 

 is moved through the air. .-Xs is well known, this 

 procedure presents various difficulties, and the securing 

 of even moderately accurate data in this manner is, 

 at the best, extremely laborious. Probably the least 

 troublesome way of applying this method is by in- 

 stalling measuring apparatus on the aeroplane itself, 

 and it seems probable that only in this way can an 



