4 Trans. Acad. Sci. of St. Louis. 
gun to flow from the anode. This operation extends 
throughout the tube, up to the dark space at the cathode. 
At the cathode end the negative particles appear. In the 
are light such a cathode stream shows itself capable of 
beating a crater into the end of the positive carbon, and 
raising the temperature of that carbon a thousand de- 
grees or more above that of the negative carbon. In the 
Geissler tube this cathode stream apparently beats the 
gas molecules away from the cathode. They are beaten 
towards the positive terminal of the tube. A condition 
is thus formed around the cathode which approaches that 
in the Crookes tube. We may have then in this space a 
region of increased ‘‘resistance’’ to the passage of the 
discharge. A kind of automatic valve action may be thus 
brought about. A system of standing waves may result, 
in the air column, somewhat resembling that in an organ 
pipe. All of this would involve, at any one point in the 
tube, harmonic changes in pressure in the gas, such as 
exist in an organ pipe, and harmonic changes in the ‘‘re- 
sistance’’ offered to the discharge. If the cathode has a 
form which gives proper direction to the cathode stream 
a counter discharge of positive ions towards the cathode 
end of the tube may be brought about. 
Such periodic changes in the gas column of the Geissler 
tube would of course be attended by many complex auxil- 
iary phenomena which are not to be found in vibrations 
in the air column of an organ pipe, produced by a con- 
tinuous blast of air. It certainly seems possible that the 
cathode stream across the dark space around the cathode, 
even when a constant current source is used, may be the 
cause of the periodic vibrations of a more or less regular 
character involved in the striae and dark spaces. Why 
should such mechanical considerations not enter into the 
explanation of these long known phenomena? 
It certainly does not seem possible that the positive 
ions can emerge from within the metal conductor form- 
ing the anode. They are what is left of the atom, when 
the negative particles have been detached from atoms of 
