250 ADVANCED ELECTRICITY AND MAGNETISM. 



* I 



Fig. 1926. 



Figure 193 represents a tapering magnetic field the intensity of 

 which at any place along the line AB is represented by the 

 ordinate y of the inclined straight line CD. Looking endwise 

 at the lines of force of the magnetic field one may, as it were, 



B 



lines of force 



of magnetic 



field 



> side view 



}end view 

 (from below 

 in upper 

 part of 

 figure) 



axis of v reference_ 



Fig. 193. 



see the ether cells rotating as shown by the curved arrows in the 

 end view, Fig. 193, cell a rotating at high speed and cell b 

 being stationary. The result of this difference of speed is to 



