APPLIED MATHEMATICS 183 



On the question whether it is possible to find observational 

 means of discriminating between the classical and the relativity- 

 dynamics as applied to planetary motion, other than that 

 referring to the perihelion of mercury, J. Trousset {Comptes 

 Rendus, 174, 1922, 1160-1) shows that apart from the motion 

 of the perihelion of mercury, observational accuracy of one- 

 thousandth of a second of arc would be required in order to 

 distinguish between the gravitational theories of Newton and 

 of Einstein. 



The " crucial phenomena " are the subject of further 

 investigations. A paper by L. Lecornu {Comptes Rendus, 

 174, 1922, 337-42) is mainly an attempt to explain the motion 

 of the perihelion of mercury and the bending of a ray of light 

 moving past the sun, by means of additional forces perpen- 

 dicular to the path, forces that " can be regarded as mani- 

 festations of the presence of the ether, and by means of which 

 astronomical phenomena can be explained . . . without forcing 

 human intelligence to sacrifice its intuitive notions of space 

 and time." It is of interest to note that Lecornu takes the 

 view that the path of a ray of light is also a planetary path. 

 Further, G. Bertrand {ibid., 174, 1922, 1687-9) shows that by 

 using Riemann's electromagnetic law of action results are 

 obtained for the motion of perihelion and the bending of light 

 similar to Einstein's. M. Ferrier {ibid., 174, 1922, 1404-7) 

 discusses the explanation of the bending of light by means of 

 an atmosphere on the moon. 



Other recent papers that should interest applied mathe- 

 maticians are : 



DiENES, P., Sur la connexion du champ tensoriel, Comptes Rendus, 174, 

 1922, 1167-70, where the author objects to Weyl's and Eddington's 

 generaUsed tensorial geometry. 



Jaffe, G., Bemerkungen iiber die relativistischen KeplerelHpsen, Ann. 

 der Phys., 67, 1922, 212-26. The author considers the motion of a 

 body of small mass and small charge in the field due to a body of large 

 mass and large charge, on the basis of the general theory of relativity. 

 He explains why we must use the generalised equations in dealing with 

 the motion of the perihehon of mercury, while the restricted theory is 

 sufficient in dealing with the motion of an electron in an atom. 



Sagnac, G., Les invariants newtoniens de la matiere et de I'energie radiante, 

 at I'ether raecanique des ondes variables, Comptes Rendtis, 174, 1922, 

 29-32. 



Wrinch, D., The Theory of Relativity in Relation to Scientific Method, 

 Nature, 109, 1922, 381-2. 



Brillouin, M., Champ isotrope : Sphere fluide h^terogdne, Comptes Rendus, 

 174, 1922, 1585-9, who extends Schwarzschild's solution of Einstein's 

 equations to the case of a sphere in which the matter is in the form of 

 concentric layers of different densities. 



Sanger, M., Sur une coincidence remarquable dans la theorie de relativite, 

 ibid., 174, 1922, 1002-3. The coincidence is that Schwarzschild's 

 solution for empty space round a point mass can be derived from the 

 Lorentz transformation. 



