1506 THE BELL SYSTEM TECHNICAL JOURNAL, NOVEMBER 1953 



ever, has to be made. All these measurements, although made at a 

 voltage range between 50 and 400 volts corresponding to a contact 

 separation range between 1500 and 100,000A, had high maximum cur- 

 rents above 1.5 amperes. The energy dissipated in each arc was of the 

 order of thousands of ergs. This reservation is made because recent 

 studies of metal transfer have indicated a reversal in the direction of 

 transfer between the anode and the cathode depending on the rate of 

 energy dissipation in the arc. 



ACKNOWLEDGEMENTS 



I am indebted to L. H. Germer, P. Kisliuk and F. H. Haworth for 

 much valuable discussion and to A. S. Timms for assistance with many 

 of the experiments reported here. 



