in the Motion of the Magnetic Field. 331 



But in the case of deformations produced by exterior forces 

 f SF is, in natural conditions, either nil or a positive quantity. 

 Therefore fl<iH is a negative quantity, and magnetization 

 proceeds along the curve in a direction opposite to that in 

 which clock-hands move; and the work performed by the mag- 

 netic field is positive, and leaves the body in the form of heat. 



Thus, in conclusion, we see that, from the point of view of 

 the hypothesis which considers the magnetic induction as a 

 hind of motion of cether communicated also to matter, we can 

 explain the phenomenon of magnetization as a simple re- 

 flexion of tubes of induction from matter, where this reflexion 

 appears with or without a change of sign, with this or 

 that intensity, depending on the forces of reaction of matter 

 which exist at the moment of reflexion. These forces of 

 reaction depend, in their turn, firstly, on the inertia of 

 matter in relation to the magnetic motion and on the coeffi- 

 cient of connexion of aether and matter, which determine the 

 sign of reflexion; secondly, also on the elastic forces in these 

 substances in which magnetic motion is accompanied by 

 magnetic deformations. In those bodies which have a 

 comparatively large magnetic inertia, the reflexion takes place 

 with change of sign and the intensity of reflected induction is 

 greater, the less the inertia and other forces of resistance ; this 

 is a normal magnetization, and these bodies are so-called dia- 

 magnetic bodies. In others where the inertia is less than a 

 certain quantity, the reflexion takes place without change of 

 sign, and every increase of resistance of matter is accompanied 

 by increase of reflexion. These are so-called paramagnetic 

 bodies. 



By following in this way the hypothesis treated of here, 

 one can reduce to the same principles the phenomena observed 

 at rapid and alternate magnetization and find an answer to the 

 very important question of the existence of magnetic inertia 

 and viscosity, and of their role in the magnetic circuit. This 

 question, however, necessitates very minute study, and we 

 shall return to it in the future. At present we will only 

 remark that the results to which this hypothesis brings us are 

 directly opposed to those which are arrived at from the point of 

 view of Weber-E wing's theory. In opposition to this theory, 

 the magnetization of iron here rises with the increase of 

 resistance offered by the forces of inertia or viscosity. In 

 this way inertia, when the magnetizing current is closed 

 rapidly, must involve a greater magnetization; the same is to 

 be said concerning viscosity; on the other hand, when mag- 

 netizing current is alternate, viscosity alone increases it ; 

 whereas inertia lessens it ; and as in all probability, owing to 



