280 Prof. J. J. Thomson. The Resistance of [Jan. 17, 



If we suppose that the rate of propagation of the electrostatic 

 potential is exceedingly small, q and q' will be very large, so that 

 unless v'cf vq, the denominator of the right hand of (15) will be 

 exceedingly large, so that the case is the same as when v = v, and 

 therefore the rate of propagation of a disturbance through a wire the 

 same as that of electrodynamic action through air. 



We shall now investigate the time of vibration of a system con- 

 sisting of a straight wire connecting two spherical balls. Let us 

 take the middle of the wire as the origin, and suppose that the flow 

 of electricity is symmetrical about this point; at points equidistant 

 from the origin the electrostatic potential will be equal and opposite. 



Using the same notation as before, let 



= C(e imz e- Lmz )e i P t J Q (tqr) in the wire, 



gV) in the dielectric, 



H = A(e^+e- l z )e^J Or) + - in the wire, 



ip dz 



B(e tmz + e- lwia )e l P*I (//ca) -f - ^ in the dielectric. 



ip dz 



If w is the intensity of the current parallel to the axis of z, 



= Atp(e l - mz +e- imz )e'-P t J (mr) (V l)Cw?(e twl2 -f e- 



The quantity of electricity Q which has passed across any section 

 at right angles to the axis is given by 



= I 



dt 



J o 



snce 



r dr 



r3 Q (mr)dr = amJ '(ma) = ~ J '(ma), 



we see that 

 ~dT~ 



