through Exhausted Tubes without Electrodes. 447 



There is no discharge through the secondary, if it is of such 

 a kind that, considering a closed curve drawn in it, the electro- 

 motive intensity as we travel along the curve tends to 

 polarize the particles in one half of the chain in one direction, 

 and in the other half in the opposite direction, the direction 

 being reckoned relative to the direction we are travelling 

 round the curve. Thus, for example, if we take a tube whose 

 axis is bent back on itself, as in the figure, the electromotive 

 intensity will tend to polarize the particles in one part of the 

 chain in the direction of the arrow, and those in the other 

 in the opposite direction ; it is impossible to get a discharge 

 through a tube of this kind. 



Fig. 9. 



Fiff. 10. 



On the other hand, the molecules exhibit remarkable powers 

 of making closed chains for themselves when not 

 actually prevented by the action of the electro- 

 motive intensity. Thus the discharge will pass 

 through a great length of tubing in the secondary, 

 even if it is bent up as in fig. 10, where the 

 vertical piece in the upper part of the secondary 

 is at right angles to the direction of the electric 

 force, and where the molecules will receive no 

 help in forming closed chains from the action of 

 the external electromotive forces. I have suc- 

 ceeded in sending discharges through tubes of 

 this kind 12 to 14 feet in length. 



Screening Effects due to the Currents in the Tubes. 



One very noticeable feature of these discharges is the well- 

 defined character of the ring, if the pressure is not too low. 

 If a large bulb is used for the secondary with the primary 

 just outside it, when the sparks pass between the jars a 



