Trowbridge — Magnetic Field and Coronal Streamers. 195 



The results are as follows: 



1. When the anode in an X-ray bulb is also the end of 

 a powerful electromagnet the application of the magnetic 

 field results in the production of X-rays from a bulb which 

 cannot be excited without the application of heat. 



2. When the cathode forms the magnetic pole a violet 



brush-like light appears on the cathode, on the side away 

 from the electromagnet; while the fluorescent light is forced 

 somewhat beyond the cathode. 



3. The use of Leyden jars in the case of low potential 

 coils greatly modilies the effect of the application of the 

 magnetic field, while with coils giving sparks over 20 cm. 

 with comparatively large Leyden jars in circuit the applica- 

 tion of the magnetic field to either anode or cathode results 

 in greatly increased production of X-rays. 



4. The application of a strong magnetic field at the anode 

 with lines of force along the line of electric discharge forms 

 a safe and useful method of regulation of X-ray bulbs. 



5. An electrometer connected to the terminals of the 

 exhausted tube shows a diminution of the apparent resistance 

 of the tube when the anode is made the magnetic pole ; and a 

 rise in resistance when the cathode constitutes this pole. With 

 Leyden jars in circuit the magnetic pole separates the oscilla- 

 tions, and rectifies the discharge to a certain extent. 



