Roever — Geometrical Properties of Lines of Force. 279 



2. The system having electric charges of like signs corre- 



1 X XI • I • 1 y-»ni S left handed ) 



sponds to the case in which Oi^has < .,,,,_,> rotation 



and PD has a motion to the < ,^ 



I left 



:-ight handed 

 Fig. 2. 



Fig. 3 shows the lines of force proceeding from a system 



consisting of one electrified plane AB and an electrified line 



A, V 



O parallel to this plane.* In the figure — = — = r^ = 01. 



air nir 



These are the curves that would be seen b}-- looking at the 



wheel of a passing wagon through a picket fence. In this 



Fig. 3. 



case, however, the concave portions of the curves would be 

 upward regardless of the direction in which the Wiigon is mov- 

 ing, so long as the wheel receives its rotary motion by rolling 

 on the ground. 



* The lines of force do not extend beyond (below in Fig 3 ) the elec- 

 trified plane, but terminate in it. The equations, however, represe' t curves 

 Which extend indefinitely beyond the electrified plane. 



