348 Trowbridge — Electric Discharges through Hydrogen. 



possible to employ the revolving mirror. The only method 

 which seemed to promise any results in detection of possible 

 stratifications was the employment of a portrait lens of large 

 aperture — four inches — in photographing single discharges. 

 Accordingly a discharge tube was filled with hydrogen and 

 exhausted to the striae stage. A condenser of *02 mf. capacity 

 was charged to a difference of potential of 10,000 volts and 

 discharged through the rarefied tube by flat copper bands of 

 inappreciable self-induction. The photographs showed unmis- 

 takable strise, superposed upon the general illumination of the 

 tube. It is difficult to reproduce the photographs by half 

 tones. 



With an anode consisting of a rim of wire placed in a cylin- 

 drical tube '6 mm internal diameter a striation is formed at a 

 short distance from the anode by condenser discharges and there 

 are traces of similar striations at greater distances along the 

 tube. If these striations are formed by ionization by collision, 

 the time of ionization is that of the duration of the pilot spark, 

 a time which at present is beyond our power of measurement. 



Doppler effect. 



When two anodes and two cathodes are employed in the 

 form of tube represented in tig. 7, there are two canalstrahlen 

 which emanate from orifices in the cathodes in opposite 

 directions. One might suppose that the Doppler effect would 

 be modified by collision of the particles in these rays and that 

 the effect would certainly be less than when only one anode and 

 one cathode were employed — the current thus passing through 

 but one branch of the U-tube. It is true that the difference of 

 potential is less between A and D when the tube is coupled in 

 multiple circuit than when only one branch of the tube is 

 connected to the battery ; but this difference in the case I 

 studied was comparatively small. With both branches of the 

 tube constituting a multiple circuit there were two strong 

 canalstrahlen passing through the orifices in D which were 

 undistorted and which gave the same Doppler effect which 

 was obtained when only one branch of the tube was excited. 

 It seems difficult to reconcile this result with any theory of 

 flow. 



Conclusions. 



1. The striae in Geissler tubes are analogous to waves set up 

 in narrow channels by opposite pulsations of different periods. 



2. Strige are greatly influenced by the direction of cathode 

 rays. 



