RECENT ADVANCES IN SCIENCE 547 



hydrodynamics. The mathematical treatment by Berry is 

 applied by Bairstow to the discussion of some particular 

 problems. Other papers on this and allied subjects are : 



WEBB, H. A., and Lang, E. D., Struts of Conical Taper, Aer. Journ. 1919, xxiii. 

 179-86, where it is proved that in the best form of such a strut the cylindrical 

 part is one half of the whole length, and the diameter of each end is one half 

 of the maximum diameter. 



Cowley, W. L., and Levy, H., Vibration and Strength of Struts and Continuous 

 Beams under End Thrusts, Proc. Roy. Soc. 1919, 95, A, 440-57, the results of 

 which are applicable to the wing spar of an aeroplane in actual flight, with a 

 throbbing engine. 



LE Cocq, G. L., Sur une propriete tres generate des cables servant aux transports 

 aeriens, Comptes Rendus, 1919, 168, 761-4. 



Seegar, M., and PEARSON, K., De Saint- Venant Solution for the Flexure of 

 Cantilevers of Cross-Section in the form of Complete and Curtate Circular 

 Sectors, and on the Influence of the Manner of Fixing the Built-in End of the 

 Cantilever on its Deflection, Proc. Roy. Soc. 1919, 96, A, 211-32. 



Mesnager, M., Valeurs maxima de la tension pres de la face inferieure d'une 

 plaque carree supportant une charge unique concentree en son centre, 

 Comptes Rendus, 1919, 168, 392-5. 



Leblanc, M., Sur les rotations tres rapides, ibid. 1919, 169, 627-33. 



JEFFCOTT, H. H., The Lateral Vibration of Loaded Shafts in the Neighbourhood 

 of a Whirling Speed— The Effect of Want of Balance, Phil. Mag. (6), 1919, 



37, 304-14- 

 Lees, S., The Whirling of an Eccentrically-loaded Overhung Shaft, ibid. (6) 



1919,37, 515-23- 

 Eason, A. B., Critical Speeds of Machinery placed on Upper Floors of Buildings, 

 as Related to Vibration, ibid. (6), 1919, 38, 395-402. 



An aerial trailing from an aeroplane in flight takes up a 

 position of relative equilibrium depending on the weight and 

 the air resistance. The form is investigated by J. Holling- 

 worth : " On a New Form of Catenary " {Phil. Mag. (6), 1919, 

 38, 452-63). In its essentials the problem is that of a flexible 

 string suspended from a fixed point and in equilibrium under 

 its weight and the pressure of a steady wind. The author 

 assumes that on each element of the string there acts a normal 

 force due to the air resistance, and proportional to the square 

 of the normal component of the velocity. The results are 

 compared with the observed forms of aerials (in so far as such 

 observation is at all possible), and the agreement is not un- 

 satisfactory. It would be useful to consider other values of 

 the normal wind force. The present writer has during the 

 last two or three years worked out a number of such cases as 

 lecture exercises, and has obtained some really interesting results. 

 Sound detection has played an important part in war 

 strategy, and is of perennial interest as a means of safety at 

 sea. The subject is investigated by L. V. King : " On the 



