116 DR. W. G. DUFFIELD, MESSRS. THOS. H. BURNHAM AND A. H. DAVIS ON 



West 



ft Amps. 10 



Fig. 8. Direct current, Series B. 



Showing the total pressures measured when the fixed carbon was placed East and West of the suspended 

 carbon. The mean curves give the values of the pressure when the effect of the earth's magnetic 

 field has been eliminated. 



TABLE IV. (BURNHAM). Direct Current. Variation of Total Pressure with Current. 

 Arc-Length Constant (3 '5 mm.). After Correction for the Earth's Field and 

 Electromagnetic Effects. 



The figures in brackets indicate the number of observations where more than one were made. 



