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DEFENDANT'S EXHIBIT U 



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Polarization Phenomena in X-Ray Bulbs. 193 



circuit) is irreversible, so that for certain values of tliis 

 parameter the amplitude may be either zero or finite 

 according to rhe method of approach to the set of conditions 

 in question. 



It is shown theoretically that in such cases of irreversibility 

 it should be possible to cause the amplitude to jump from 

 the zero to the finite value by means of an electrical impulse 

 greater than a certain amount. Experimental confirmation 

 of this was obtained by using the transient electromotive 

 force from a coil and moving bar magnet. 



The relation between the critical parameters for starting 

 and stopping oscillations and the maintained electrode 

 potentials has been investigated experimentally, and it is 

 found that there is usually a region of grid potential in 

 which the amplitude is a single-valued function of the circuit 

 parameters, so that here the conditions for starting and 

 stopping oscillations are the same. For such values of grid 

 potential it may be concluded that the- oscillation character- 

 istic may be approximately represented by a simple power 

 series of three terms. 



For other values of grid potential a difference in the 

 critical circuit constants is found, always accompanied by 

 the possibility of oscillation-hysteresis. A simple power 

 series of five terms for the oscillation characteristic must 

 be used to account for the phenomena in such cases. 



Experimental evidence of the possibility of two stable 

 amplitudes, both differing from zero, has also been obtained 

 This is a phenomenon depending on the seventh differential 

 coefficient of the oscillation characteristic. 



Teyler's Stichting, 



Haarlem, Holland. 



XVI J. Polarization Phenomena in X-Ray Bulhs. By 

 S. Katner, University of Manchester* . 



Introductory. 



1. XT IT H E RT the sparking potential in well exhausted 

 JZL vacuum tubes has been considered to be the property 

 of the gas in the tube, being determined entirely by the 

 nature and the pressure of the gas. It has been noticed 

 that gases occluded by the electrodes facilitate the dis- 

 charge, but only in so far as they increase the pressure 



* Communicated by the Author. 

 Phil. Mag. S. 6. Vol. 43. No. 253. Jan. 1922. 



