Trowbridge — Magnetic Field and Coronal Streamers. 191 



electromotive force and great current density, one can observe 

 phenomena of rotation which cannot be photographed yet 

 which present to the eye a strong analogy to the appearance of 

 coronal streamers. 



I arranged a number of collections of bristles on a disc 

 which was then set in rapid rotation. Fig. 2 is a photograph 

 of' the appearance of such revolving streamers, which repre- 



sent fairly well what may be seen at the terminal of a dis- 

 charge tube in a magnetic field. 



There is, however, another magnetic phenomenon which 

 may have a bearing upon the coronal streamers at the poles of 

 the sun. When the lines of magnetic force are at right angles, 

 or transverse to the direction of the electric discharge, at com- 

 paratively high pressures, one to two centimeters, with currents 



