352 HELL SYSTEM TECHNICAL JOURNAL 



advantages. On the philosophical side, there is the prospect of greater 

 unilication of the basic theory through a reduction in the number of inde- 

 pendent assum])tions. Matter and radiation appear as wave motions which 

 satisfy the same equations. The apparent conflicts between current concepts 

 appear to be reconcilable through a more exact determination of the con- 

 ditions under which each applies. On the more practical side, the ether 

 model provides a difTerent approach and technique. It has the advantage 

 inherent in all models that, once one is found which fits one set of condi- 

 tions, a study of its properties under widely different conditions may bring 

 out relations which it would be difficult to postulate solely on the basis of 

 observations made under the second conditions. The suggested existence 

 of particles having negative inertia, as discussed near the end of the paper, 

 should it lead to anything of value, would be an example of such a relation. 

 Also it makes available the added relationships which are characteristic of 

 non-linear equations, without encountering those difficulties with respect 

 to absolute motion which may arise when non-linearity is introduced ar- 

 bitrarily. While the working out of the quantitative relations involved is 

 a rather formidable undertaking, any effort in that direction may well 

 throw new light on those problems which have not yielded to other methods. 



The Gyrostatic Ether 



As stated above the specific form of gyrostatic medium on which the 

 present discussion is based is the ether model proposed by Kelvin. This is 

 discussed in detail in a companion paper. ^ It is there shown that, for in- 

 finitesimal displacements, it is characterized by the wave equations: 



vx(f)=.f 



where po is the density, tjo is a generalized stiffness determined by the con- 

 stants of the medium, q is the vector velocity, and T is a vector torque per 

 unit volume, which has its origin in the torque with which a gyrostat op- 

 poses an angular displacement of its axis. For a plane polarized plane wave, 



T . 



the quantity can be interpreted as a surface tractive force per unit area, 



which a layer of the medium normal to the direction of propagation exerts 

 on the layer just ahead. Its direction lies in the surface of separation, and 

 is parallel to that of the velocity q. 



' R. V. I.. Hartley, "'J'hc Rctlcction of Diverging Waves by a Gyrostatic Medium" — 

 this issue of The Bell Svstem Technical JournaL 



