234 



DISCHARGE OF ELECTRICITY. 



It will be useful to consider here the dispositiou aud motion of the 

 tubes of electrostatic induction in the arrangement used to produce 

 these electrodeless discharges. We shall take the case where two jars 

 are used, as in fS, Fig. 1, as being the more symmetrical. 



Just before the discharge of the Jar, the tubes of electrostatic induc- 

 tion will be arranged somewhat as follows : There will be some tubes 

 stretching from one terminal of the electric machine to the other; others 

 will go frcmi the terminals to the neigliboring conductors, the table on 

 which the machine is placed, the floor and walls of the room, etc. The 

 great majority of the tubes will, however, be short tubes passing through 

 the glass between the coatings of the jars. Let us now consider the 

 behavior of two of these tubes, one from the jar A, the other from B, 

 when a spark passes between the terminals of the machine. Whilst the 

 spark is passing these may be regarded as connected by a conductor; 

 the tubes which originally stretched between them now contract, the 

 repulsion they exerted on the surrounding tubes is destroyed so that 

 these now crowd into the space between the terminals, the two short 

 tubes under consideration now taking somewhat the form shown in Fig. 

 2. These tubes, being of opposite sign, tend to run together; they do 



so until they meet as in Fig. 3, when the tubes break up as in Fig. 4.^ the 

 upper portion running into the spark gap, where it contracts, while 

 the lower portion rushes through the dielectric to discharge itself into 

 the wire connecting the coatings of the jars, an intermediate position 

 being shown in Fig. 5. These tubes while rushing through the dielec- 

 tric produce, as already stated, magnetic forces; some of them on their 

 way to the discharging wire will pass through the discharge tube; if 

 they congregate there in sntflcicnt density, discharge will take place 

 through the rarefied gas, , 



The discharge of the jar is oscillatory, and we have only followed the 



