250 Sir David Salomons on the Electric 



will disappear altogether and no current will pass. This stage 

 will be referred to later. In such an event raise the E.M.F. 

 until the bands are plainly seen. It will then be noticed that 

 the bands which at first extended across the tube have now 

 divided into two columns, and are very much smaller 

 than before, their position being equatorial. It will further 

 be noticed that the convex sides are all one way in one 

 column of bands and in the opposite direction in the other 

 column of bands, indicating that the two currents have been 

 completely separated and travel through the tube at opposite 

 sides, meeting only at the electrodes. Moreover, the bands 

 are smaller where the field is strongest. Also they will here 

 be placed closer together and be more numerous. In fact, 

 the condition of things can be made such, that where the field 

 is most powerful the bands disappear and a line of light only 

 is visible. But a low-power microscope will resolve this 

 line of light into bands, that is to say, they are so close 

 together that the eye alone does not appreciate their 

 existence. 



Probably the best way to make the experiment is to place 

 the tube between the poles of the magnet when excited. 

 Then cut off the exciting current, and watch the tube during 

 the time that the magnetism is falling. The various stages 

 can be seen better this way, as they take place slowly. Fig. 4 



Fig. 4. 



4< 



S 



shows the tube with the divided current appearing as two 

 lines of light. Fig. 5 illustrates one line of bands when the 



Fig. 5. 



4j (((((( HI in!.'...".,! <((((((( (^ o 



magnetism is less strong. Fig. 6 shows two lines of bands 



Fig. 6. 



v^ 



Fig. 7. 



€ 



in the tube, w T hen looked at from another point of view. 

 Fig. 7 shows the bands filling the tube, the magnetism 



