an Electromagnetic Effect. 



reversing 



201 



the 



reverse the press ure-effect produced. Also 

 field did not reverse the pressure-effect produced. 



I again used a horizontal field as in fig. 4, the stand-pipe 

 showing now the side-pressure in the tube parallel to the field. 

 It was my intention to let fig. 4 really represent fig. 3 turned 

 through a right angle, and again the mercury always rose in 

 the stand-pipe, whatever the direction of the current or 

 field. 



Pic. I 



Re. 3. 



Fig 4 



Fie 5 



Lastly, I let four stand-pipes communicate with the middle 

 of the iube. The current passing in one direction, the mer- 

 cury in B rose, in C fell, and in A and D rose only momen- 

 tarily during the starting of the current. When the current 

 was reversed, the mercury in B fell and in C rose, and rose 

 momentarily in A and D. 



The non-reversible effects of figs. 3, 4, and in the tubes A 

 and D of fig. 5 are probably due to curious motions of the 

 mercury, but it seems difficult to understand how. They do 

 not occur when the tube is far away from the magnetic field. 



Phil. Mag. S. 5. Vol. 40. No, 243. Aug. 1895. P 



