Miss P. G. Fawcett. 2he Electric Strength of [June 21, 



The results (p. 265) were obtained when no grease* was present, 

 and the spark was not able to pass except between the opposed sur- 

 faces of the plates. 



Distance between the plates = 0'047 in. 



These results are represented by the continuous curves figs. 1 7, 

 in which the abscissae represent the pressure in millimetres of 

 mercury, and the ordinates the E.M.F. in volts. The dotted curves 

 in the same figures represent the means of the results of several 

 series of observations with the earlier arrangement of the apparatus, 

 in which grease was present, and no precautions were taken to 

 prevent the discharge passing otherwise than between the plates. 



FIG. 1. 



Fio. 2. 



400 



300 



20 



ZQm.m. 



* There was always a small amount of grease on the stop-cock of the air-pump, 

 but it does not seem probable that such a small quantity would have an appreciable 

 effect. 



