4 PROPERTIES OF AN ELECTRIC CHARGE [CH. I. 



other rotational, or vortex-like motion, but, if so, it is 

 indestructible and unproducible by any known means, 

 and has not yet been discovered. 



The effect of the motion of the body, then, is to 

 relieve the strain of the ether at one place and to 

 generate it at another ; the state of strain travels 

 with the body, but through the ether. 



Regarding the matter from the point of view of 

 the ether, we might say that the field of force is 

 constantly being destroyed and regenerated as the 

 body moves. Regarding it from the point of view 

 of the moving body, we should say that it carries its 

 field with it. 



The question now arises and it is far from being 

 an easy question what sort of occurrences go on in 

 the ether when this decay and regeneration of an 

 electrostatic field is occurring, or when a field of force 

 is moving through it ? Can it adapt itself instantly 

 to the new conditions, or does it require time ? This 

 matter has been studied, closely and exhaustively, by 

 Mr. Oliver Heaviside. 



Fix the eye upon a point a mile distant from the 

 body ; does the information about the motion of the 

 body reach that point instantaneously, so that all the 

 lines of force move like absolutely rigid spokes, every 

 part simultaneously ? If so, how is the communi- 

 cation carried on, so that the distant parts of the 

 medium can be thus instantaneously affected ? Or 

 does the disturbance only arrive at the distant point 

 after the lapse of a small but appreciable time ; in 

 other words, has there to be an adjustment to the 

 new conditions an adjustment which reaches the 

 nearest parts first and the further parts later ; and if 

 so, what additional phenomena can be observed 

 during the unsettled period ? 



