124 Prof. Pliicker on the Action of the Magnet 



12. "When the tuhe was slipped along parallel to itself, so that 

 the ellipsoid moved in an axial direction from the point of maxi- 

 mum action above the approximated armatures towards either 

 one side or the other, the plane in which the attraction or re- 

 pulsion of the electrical hght-stream occun-ed no longer remained 

 vertical, but became more and more inclined, its inclination 

 being always determined by the relative positions of the axis of 

 the tube and the place of greatest action. 



13. A perfectly similarly-shaped tube, containing a small 

 quantity of hydrogen instead of the trace of phosphorus, showed 

 exactly the same appearances, with the single exception that the 

 light, instead of being red, was bright violet. 



14. When these same two tubes were so placed upon the 

 armatures that the electrical current passed through them in an 

 axial direction, the light-streams which entered the ellipsoid 

 from both sides underwent horizontal aberrations in opposite 

 directions. The stream proceeding from the light-pole termi- 

 nated as before in a brightly luminous point, which coincided 

 in position with one of the two extremities of the horizontal 

 equatorial diameters of the ellipsoid. The light-stream enter- 

 ing the ellipsoid from the warmth-pole was driven towards and 

 concentrated at the opposite side of the bulb, whence continually- 

 undulating flames were directed towards the side of the luminous 

 point. This appearance was especially beautiful when, instead 

 of the bulb-tubes described, simple cylindrical tubes of greater 

 width were taken (270 millims. long and 18 miUims. wide). The 

 undulating flames extended then for a distance greater than 

 10 centims. 



Both on reversing the electric current and on inverting the 

 magnetic polarity, the phsenomenon underwent simple inversion 

 more quickly in the first case than in the second, the luminous 

 point and the undulating light changing places. 



15. In the phsenomena just described, the direction of the 

 horizontal aberration of the light-stream is determined as in the 

 case of the moveable conducting wire. From the consideration 

 of the same case, the breaking of the light-stream above the 

 point of greatest action might have been predicted. In the pre- 

 viously described phsenomenon, however, where the light-stream 

 throughout its whole length is only attracted, such a rupture of 

 the stream by the magnet was in no way to be anticipated. 



16. I may as well mention here an isolated phsenomenon or 

 two which were observed in connexion with the action of the 

 magnet upon the electrical light-discharge through Geissler's 

 tubes. 



When the light in such tubes, especially at their widened 

 portions, is diflFused, showing no trace of stratification, the dark 



