Gitt— Theory of the Stratified Discharge in Geissler Tubes. 417 
evident that the strata can also be attributed to the presence of the 
causes which produce this “rib-like ” structure described by Lord 
Rayleigh. That is to say, that while in certain cases the strata 
may be explained as being due to the Kundt-tube effect, in others 
it seems necessary to attribute them to this secondary Kundt effect. 
So that the present note is not to be taken as a change in the 
explanation already suggested, but asa more developed form of 
the same. 
In the present Paper I propose to describe some ways in which 
this rib-like appearance is produced. Some of these I have already 
noticed elsewhere, and some are new.! 
Ie. 
IIT. 
VI. 
i 
| 
eae So 
I. Effect produced on powder when a reed pipe was sounded at its open end. 
II. Stiff paper stretched tightly over the end of the tube and tapped. 
III. Sketch of the effect produced on smoke in a tube when a reed pipe was sounded at 
its extremity. 
IV. Result produced by passing an electric spark near the extremity of a tube in which 
some powder had been sprinkled. 
V. Effect due to a small spark inside a tube in which the pressure of the air was 
about 10 mm. 
VI. This drawing represents the formation of the rib-like powder heaps in a Geissler 
tube in which the discharge which produced them was stratified. 
1 The records of the effects thus produced, shown in the figure, were obtained as 
follows:—A strip of photographic paper was placed inside the tube, and some lycopo- 
dium was sprinkled over its surface. When the effect of the spark was obtained, the 
whole was exposed to the light, and the trace of the powder was thus registered. 
Nos. III. and VI. are sketches. The various strips of photographic paper were then 
all mounted together, and a photograph was taken of the whole, thus giving a record 
of the results, which is practically full-size. 
