640 PROCEEDINGS OP THE AMERICAN ACADEMY. 



In Experiment 3 the formation of the rings indicates a superior pres- 

 sure of the positive particles shot out from the positive pointed terminal 

 against a diminished pressure of the discharge from the plate terminal 

 of the cathode. This manner of formation is analogous to that of smoke 

 rings. 



In Experiment 8 the revolving factor is greater than the progression 

 factor for both the positive and the negative ions, and the effect of the 

 field is to retard the discharge. The field seems to oppose an obstacle 

 like that of a rock in a running stream producing ripples. 



The theory of positive and negative ions moving with different veloci- 

 ties and colliding according to Townshend's Hypothesis, — an hypothesis 

 which is illuminating in regard to electric discharges in general, — does 

 not throw much light upon the phenomenon of striae. It does not seem 

 possible to form striae by the indiscriminate projection of colliding par- 

 ticles. Such striae, or stratifications, are analogous to standing waves in 

 a liquid, and if we suppose electric pulsations issuing both from the 

 cathode and the anode we can perhaps conceive of the method of forma- 

 tion of the stratifications. Even with the employment of the steady 

 current from a storage battery a high note is heard in a telephone in- 

 tercalated in the circuit which is not due to crepitations in the liquid 

 resistance employed. 



The unipolar rotation described in Experiment 6 leads my mind to 

 connect the phenomenon of coronal streamers seen at the poles of the 

 sun in an eclipse with the effect of a magnetic field on possible electrical 

 discharges between the equatorial regions of the sun and the poles of the 

 sun. If we suppose that a difference of electrical potential can arise 

 between the swiftly moving strata of gases or from the eruptions which 

 take place mainly along the equatorial belt and the polar regions, the 

 magnetic poles of the sun would undoubtedly tend to cause the resulting 

 electric discharges to revolve about the pole. On account of the vast 

 circumferential area about the poles a number of discharges could 

 occur at different points around the pole and each discharge would 

 revolve under the effect of the pole. In observing the effect of a strong 

 magnetic pole on plate terminals in wide tubes of rarefied air at compara- 

 tively high pressure of air under conditions of high 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 have arranged a number of collections of bristles on a disc, which 

 was then set in rapid rotation. Figure § is a photograph of the appear- 



