RECENT ADVANCES IN SCIENCE 527 



Another paper on the subject of propellers is by A. Plateau, 

 entitled " Theorie des helices propulsives marines et aeriennes et 

 des avions en vol rectiligne," Comptes Rendus, 170, 1920, 1360-2. 



The problem of fluid-resistance presents several difficulties. 

 On the one hand, there is the difficulty of finding the pressure 

 on any given type of barrier past which air is flowing. On the 

 other hand, the elasticity of the air introduces effects which 

 are no doubt considerable in the case of air-screws, whilst the 

 viscosity too needs investigation. Theory must be combined 

 with experiment, and several attempts to solve such problems 

 are recorded in recent papers. The following are a selection 

 on this and kindred topics : 



Bairstow, L., Towler, R. H., and Hartree, D. R., The Pressure Distribu- 

 tion on the Head of a Shell moving at High Velocities, Proc. Roy. Soc, 

 97, 1920, 202-18. 



Thurston, A. P., Distribution of Air Pressure round the Funnel of a Vessel 

 at Sea, Engineering, 119, 1920, 134-5. 



Thery, R., Sur un problfime hydrodynamique admettant une infinite de 

 solutions, Comptes Rendus, 170, 1920, 656-8. 



Fournier, F. E., Formes de car^nes de moindre resistance k leur translation 

 a air libre ci toutes les vitesses, ibid., 170, 1920, 547-52, 694-9. 



Whittemore, J. K., The Starting of a Ship, Proc. Nat. Acad. Sci., U.S.A., 

 vi, 3, 1920, 182-5 ; the author discusses the motion of a particle moving 

 under tangential forces depending only on the velocity of the particle, 

 showing its application to marine engineering and to the study of 

 resistance. 



NoGUES, P., Le vol k voile par vent horizontal de vitesse et de direction 

 invariables, Comptes Rendus, 170, 1920, 65-8, where the author tries to 

 show how such a wind can be a source of energy to enable a bird to 

 fly like a sailing-boat. The argument and result are controverted by 

 ViLLEY, J., and Volmerange, A., ibid., 170, 1920, 838-41. 



Darwin, Sir H., The Static Head Turn Indicator for Aeroplanes, Aer. Journ., 

 xxiii, 1920, 617-31. 



Rateau, a., Sur les plus grandes distances franchissables par les avions et 

 les plus grandes vitesses realisables, Comptes Rendus, 170, 1920, 364-70 ; 

 the author comes to the conclusion that a single flight of 5,000 or 6,000 

 kilometres is possible, but he is doubtful whether a flight of 7,000 

 kilometres can be attained. 



Rateau, A., Sur I'altitude de vol qui correspond au minimum de consomma- 

 tion kilometrique, et sur le calcul de la raeilleure h61ice pour un avion 

 donn6, ibid., 170, 1920, 491-7. 



Marvin, C. F., Flight of Aircraft and Deflective Influence of the Earth's 

 Rotation, Monthly Weath. Rev., 47, 1919, 75-7- 



Brewer, G., Some Kite Balloon Experiments, Aer. Journ., xxiv, 1920, 15-36. 



Cave, C. J. P., and Dynes, J. S., Further Measurements on the Rate of 

 Ascent of Pilot Balloons, Quart. Journ. Roy. Met. Soc, 45, 1919, 277-83. 



In addition there is a paper by H. Haedicke {Zeit. Ver. 

 Deutsch. Ing., 63, 19 19, 983-5), dealing with forces due to 

 oblique air-streams ; one by F. Neeson {Deutsch. Phys. GeselL, 

 21, 1 9 19, 589-93), dealing with the laws of relative motion in 

 connection with the flight of projectiles in air ; and one by 



