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BELL SYSTEM TECHNICAL JOURNAL 



twenty per cent. On Lassen's curves (hollow circles of Fig. 13), there 

 are indications that beyond the drop the curve again becomes hori- 

 zontal ; these are borne out by curves earlier obtained by Reukema with 

 6.25-cm. spheres (black dots of Fig. 13), although there are clashes 

 between the two sets of data which may or may not be entirely due to 

 the difTerence in the sizes of the spheres. 



Fig. 13 — Curves of sparking-potential vs. frequency, in atmospheric air, between 

 spherical electrodes. (Data from Lassen and Reukema; the various curves corres- 

 pond to the indicated gap-widths.) 



