422 Prof. 0. Lodge on Absolute Velocity and 



ordinarily understood is not true ; some additional words, such 

 as those above in italics or square brackets, must be appended 

 to it as a qualification in order to make it general. Only 

 then can the potential energy of a system be expressed in 

 terms of the configuration of the matter alone ; which, as 

 Larmor points out, is the most general statement of the third 

 law (Phil. Trans, vol. cxc. p. 216). 



An immediate deduction from this and the preceding state- 

 ments is that a stress cannot exist inside a single lump of 

 matter (unless it be in a closed curve); for if it had free 

 ends they would terminate in aether, since matter is only in 

 contact with aether. A stress might indeed penetrate the space 

 inside a lump of matter on its way between two other lumps, 

 but inasmuch as the stress inside could not exceed in amount 

 the aetherial stress outside (or a portion of it would be ending 

 at the surface) it follows that the aether is the vehicle and 

 medium of all stresses that exist. 



6. Stresses exist solely in the ^Ether. 



In other words the aether is essentially the seat of all 

 potential energy. 



Furthermore, since steady aether is not subject to mechanical 

 force («. e. one end of a stress) it cannot have any kinetic energy 

 imparted to it mechanically. It is improbable that as a whole 

 it has any motion at all, but whatever mechanical motion it 

 has is entirely disconnected from us, and for all practical 

 purposes it is stationary. 



7. The JEtliev as a ivhole is at rest, and Velocities referred to 



it are Absolute velocities. 

 Thus we find that matter possesses all the kinetic or simple 

 inertia-energy there is, and aether possesses all the potential or 

 stress energy. 



8. The two fundamental Forms of Energy are distinct and are 



possessed by different bodies, viz. Potential by cether, 

 Kinetic by matter; hence whenever there is transference 

 there is transformation, and whenever there is trans- 

 formation there is transference. (It is necessary to ex- 

 clude radiant, i. e. alternating energy from this state- 

 ment, at present, but it may be found that the property 

 which enables aether to alternately receive and deliver 

 electrokinetic energy is essentially a quasi-material or 

 potentially material property.) 

 Consider for instance an action between a mass of matter 

 and the aether in contact with it : the speed of the body is 

 either increasing or decreasing or remaining constant. (1) If 

 its speed is increasing, it is gaining kinetic energy and the 

 aether is losing potential energy. This is achieved not by an 

 ordinary process of recovery from elastic strain, but as it were 



