RECENT ADVANCES IN SCIENCE 529 



has least potential energy {Comptes Rendus, 170, 1920, 510-11). 

 K. Sen investigates the potentials of elUptic cyHnders and of 

 incomplete ellipsoids and elliptic discs {Bull. Calc. Math. Soc, 

 1919, 11-27, 157-78), whilst G. Prasad takes the case of a 

 surface distribution having a discontinuity {ibid., 1919, i-n), 

 and S. C. Dhar considers Joachimstahl's Attraction Problem 

 {ibid., 1919, 151-6), Of a more theoretical nature are the note 

 by G. Bouliyaud, " Sur le probleme de Dirichlet par un domain 

 infini " {Comptes Rendus, 169, 191 9, 1020-3), and the paper by 

 P. Levy, " Sur Failure des fonctions de Green et de Neumann 

 dans le voisinage du contour " {Acta Math., ^2-2, 1919,207-67). 

 Other recent papers, dealing with various branches of applied 

 mathematics, are : 



Statics and Dynamics 



Fawdry, R. C, The Teaching of Mechanics to Beginners, Math. Gaz., x, 

 1920, 30-4, containing a discussion of interest to teachers of mechanics 

 in schools. 



Thebault, v.. Distance du centre de la sphere circonscrite au centre de 

 gravite du tetraedre, Nouv. Ann. Math., 1919, 424-6. 



BiMBi, J. L., Principio de los trabajos virtuales. Applicaciones, Cont. Estud. 

 Cienc. fis. y mat., 1919, 9-71. 



Marton, W. B., and Tobin, T. C, Note on the Construction of a Parabolic 

 Trajectory and a Property of the Parabola used by Archimedes, Phil. 

 Mag. (vi), 39, 1920, 157-60. 



Hadamard, J., Rapport sur les travaux examines et retenus par la Com- 

 mission de Ballistique pendant la duree de la guerre, Comptes Rendus, 

 170, 1920, 436-45 ; these investigations included the discussion of the 

 cases where integration by quadratures is possible for the motion of a 

 projectile in air for various laws of resistance, the actual calculation 

 of paths and the perturbations of paths, the relation between the density 

 of air and altitude, as well as internal ballistics and experimental work. 



Le Rolland, P., De I'influence de la deformation du couteau et du plan de 

 suspension sur la dur^e des oscillations du pendule, ibid., 170, 1920, 455-7- 



Jackson, L. C, Variably Coupled Vibrations, Gravity-Elastic Combinations, 

 Masses and Periods Equal, Phil. Mag. (vi), 39, 294-304, a continuation 

 of Browning and Barton's work. 



Milne, J. R., A Duplex Form of Harmonic Synthetiser and its Mathematical 

 Theory, Proc. Roy. Soc. Edin., xxxix, 1920, 234-42 ; it is claimed that 

 this obviates the obliquity error that troubled Lord Kelvin. 



Andrade, J., Sur le controle experimental des vibrations pendulaires 

 doublement amorties, Comptes Rendus, 170, 1920, 42-4, deals with 

 harmonic motion in which there is a resistance varying as the speed 

 and a constant frictional force. 



Andrade, J., Sur le mouvement de I'axe d'un solide homogene pesant de 

 revolution qui a un point fixe sur cet axe, ibid., 170, 1920, 1156. 



Brown, S. G., The Brown Gyro Compass, Nature, 105, 1920, 44-8, 77-80. 



Graumel, R, {Phys. Zeit., xx, 1919, 398-400), discusses the nutation of the 

 unsymmetrical gyroscope. 



DE Fontviolant, B., Calcul des ponts circulaires, comportant un seul con- 

 treventement et des entretoisements dans toute leur longeur, Comptes 

 Rendus, 170, 1920, 376-9, 796-8. 



Raman, C. V., Forced Vibrations of Strings, Phys. Rev., 14, 1919. 446-9- 



Raman, C. V., Partial Tones of Bowed Strings, Phil. Mag. (vi), 38, 1919. 

 573-81. 



