NATURE 



[August 25, 1910 



of very varied forms, and furnished, as a rule, with 

 eight cusps, four of which correspond to grazing inci- 

 dence of the air on one or other plane. Into 

 the relative uses of statical and dynamical 

 methods of approaching' the problem of stability 

 it is not necessary to enter at great length, 

 although Prof. Brillouin refers to this question 

 in the introduction. It must be pretty evident 

 to anyone who has studied the problem that 

 both methods must be pushed to their ultimate con- 

 clusions before aviation is reduced to an e.^act science; 

 and further, our 1004 papers on dynamical stability 

 were never intended to be final. What Prof. Bril- 

 louin has done is to reduce materially the amount of 

 work still remaining to be done in a field of investiga- 

 tion of a new and difficult character. 



Exactly the same remarks apply to Prof. Reissner's 

 article (q). The steering of aeroplanes in turning 

 curves is a difficult problem, which up to the present 

 has not received the attention that it deserves, with 

 the result that a great deal of an aviator's attention 

 is devoted to counteracting the tendency of aeroplanes 

 to turn in circles, or sometimes, not improbably, to 

 describe spirals with decreasing convolutions until, if 

 unchecked, they would twizzle round and fall like the 

 seeds of certain trees. In fact, as Dr. Reissner him- 

 self points out in his introduction, 



"on the motion in a curved path we find only meagre 

 references, in which it is only attempted to satisfy 

 one equation of equilibrium, instead of considering 

 the six, as is necessary with every body moving in 

 free space." 



Dr. Reissner has used approximate methods ; for 

 example, in places he assumes the radius of the curve 

 to be large. Anyone working at problems of this class 

 will realise the necessity of employing such methods 

 of approximation in order to reduce the mathematical 

 work to a minimum in the early stages of the inves- 

 tigation. When one is thoroughly familiar with the 

 simplest solutions, it becomes much easier to take 

 account of modifications in which some of the terms 

 previously neglected are re-introduced. 



While on the subject of steering, it is interesting to 

 refer to the Dunne biplane, of which a short account 

 is given in the Aeronautical Journal for July, and of 

 which a noticeable feature is that the planes actually 

 have a negative angle of attack near the tips, so as to 

 receive a downward pressure there. It is evident that 

 by such a method it is possible to counteract the tend- 

 ency of most aeroplanes to heel over excessively to the 

 inside when rounding curves without making the lift 

 vanish. 



The report is before us (10) of the fourth International 

 Congress of Aeronautics, which met at Nancy from 

 September 18 to 23, 1909. The attendance at this 

 congress was smaller than one might have expected, 

 the membership list containing just over seventy 

 names, but including Government delegates from the 

 United States, Belgium, France, Italy, and Russia. 

 The congress was divided into three sections, of which 

 the first, devoted to aerostation, appears to have 

 given considerable attention to aeronautical carto- 

 graphy and navigation proper. In the reports of the 

 NO. 2130, VOL. 84] 



second section (aviation) we find discussions of pro- 

 peller-thrust, laws of air resistance, the efficiency of 

 motors, and other matters of like character, while the 

 third section was devoted to scientific and other ques- 

 tions of a somewhat more miscellaneous nature. 



The interest of the Smithsonian Institution in 

 aeronautics dates almost from the commencement of 

 its work, and this interest has been greatly stimu- 

 lated through the secretaryship of the late Dr. Samuel 

 Pierpont Langlev, who brought with him to the insti- 

 tution the nucleus of a library of aeronautical litera- 

 ture. A most fitting memorial or tribute to his ser- 

 vices to aeronautics is afforded by Mr. Paul Brockett's 

 "Bibliography of Aeronautics" (11). While primarily 

 intended as a catalogue of the material contained in 

 the Smithsonian collection, this volume of 940 pages 

 will prove a valuable — perhaps an indispensable — work 

 of reference in the hands of every student of aero- 

 nautics. 



A work of reference of a rather more popular char- 

 acter is M. Ventou-Duclaux's "Petite Encyclopedic 

 aeronautique " (12). The reader who wishes to follow 

 intelligently the records in the daily Press of aviation 

 meetings and fatalities requires some information re- 

 garding the meaning of such terms as Gnome motor, 

 carburettor, Curtiss biplane, Panhard motor, centre 

 of pressure. All such expressions he will find ex- 

 plained if he consults this little dictionary. For some 

 reason " Virage " does not occur. 



The "Encyclopaedia of Sport" (13), which is to be 

 completed in thirty parts, opens with an article by 

 Lord Montagu of Beaulieu on aeronautics. It con- 

 tains a good, popular account of the subject, well 

 illustrated by photographic reproductions of the chief 

 aeroplanes and dirigibles, and of most of the " record " 

 flights, such as BWriot's Channel flight, Paulhan's 

 Manchester flight, and the flights of the principal 

 French and German military dirigibles. The other 

 articles in this number are on "Alligator," "Ammuni- 

 tion," "Angling," "Antelopes" (the last unfinished). 



In the Revue des Sciences for June, 1908, Captain 

 Paul Renard discussed the problem of the dirigible 

 balloon. In the issues for April last he has given a 

 couple of general articles on the problems of aviation. 



Mr. Walter Child, of 35 Alfred Place West, London, 

 S.W., has printed on a small card a diagram showing 

 graphically the results of a new determination of the 

 position of the centre of pressure of a lamina (a 

 rectangular plate of magnalium) for varying angles 

 of attack. According to him the centre of pressure 

 approaches the front edge when the angle of attack 

 vanishes. The method employed was to poise the 

 plate on any assumed axis, to revolve it on a whirling 

 table, and to read off the angle after the plate has 

 come to the position of equilibrium. It may be men- 

 tioned that a rough and ready way of demonstrating' 

 the shift of the centre of pressure is by loading a 

 rectangular glider and balancing it upon a finger, so 

 that the centre of gravity occupies a known position, 

 and then ascertaining by trial at about what angle 

 the glider will fly if suitably projected. Mr. Child 

 would have been wise to state the length and breadth 

 of his lamina, and in view of the divergence of opinion 



