CHAPTER IV. ARC RECTIFICATION. 249 

16. The rectifying character of the arc. 249 

17. Mercury arc rectifier. Constant-potential and constant- 

current type. 250 

18. Mode of operation of mercury arc rectifier: Angle of 

over-lap. 252 

19. Constant-current rectifier: Arrangement of apparatus. 255 

20. Theory and calculation: Differential equations. 256 

21. Integral equations. 258 

22. Terminal conditions and final equations. 260 

23. Calculation of numerical example. 262 

24. Performance curves and oscillograms. Transient term. 263 

25. Equivalent sine waves: their derivation. 267 

26. 25 Continued. 269 

27. Equations of the equivalent sine waves of the mercury arc 

rectifier. Numerical example. 271 

SECTION III. TRANSIENTS IN SPACE.