524 Luminous Discharges in Electrodeless Vacuum-Tubes. 



discharge in the bulb, and act similarly to an exhausted bulb 

 secondary. In the second experiment a low resistance se- 

 condary behaves in the reverse manner to an exhausted bulb 

 secondary, while (c) and (e) show that a high resistance put 

 externally into the secondary circuit, and (d) that a secondary 

 having a high resistance in itself, act in a similar manner to 

 an exhausted bulb secondary. (b) shows that if the ends of 

 the secondary be attached to a capacity it behaves like the 

 bulb. 



The most probable explanation seems to be the following: — 

 The amount of energy in the jars when charged is a fixed 

 quantity for a given spark-gap ; this energy will be mostly 

 expended in the coil ft and the single turn and bulb (the 

 second experiment). If, now, we can make energy be ex- 

 pended elsewhere, as in a secondary, we shall have diminished 

 the energy received by the bulb, and this will in general dim 

 it or altogether extinguish it. This will explain what happens 

 when an exhausted bulb secondary is used ; also experiments 

 (a), (c), (d), and (e). With regard to experiment (b), energy 

 may have been expended in heating the glass of the jar on 

 account of electric hysteresis. Moreover, this secondary did 

 not dim the bulb so much as the others, but was found to be 

 capable of improvement in this respect by including some 

 resistance (in the shape of the glow-lamp or a strip of gilt 

 paper) in its circuii. 



In the case of a low- resistance secondarj^ the energy dissi- 

 pated in it will be small, since its impedance will not be much 

 lessened by its being of low resistance on account of the high 

 frequency. This does not explain, however, why the dis- 

 charge in the bulb is brighter when a low-resistance secondary 

 is used*. 



A further experiment was then made. The coil R in the 

 second experiment had a similar secondary S placed in it ; 

 this was connected to another similar coil T. The spark-gap 

 was lengthened until a brilliant luminous ring was produced 

 in a bulb placed in T. The bulb in A was then moved away 

 from A until there was a very faint luminous ring in it. On 

 removing the bulb from T a very slight brightening of the 



* Tnis energy explanation is probably not a complete one. Working 

 out the frequency in the cases of no secondary, a secondary of four turns 

 short-circuited, and the same with its ends joined through 100 w ; 

 the author finds that the damping-torm is increased when either secondary 

 is used, but more so with tho 100" in circuit. The frequency is much 

 the same with the 100"> in circuit as when there is no secondary, hut 

 with the secondary short-circuited the frequency is about doubled. " This 

 may account for the increase in brightness of the discharge in the bulb. 



