698 



Prof. 0. Kinsley on 

 Fig. 4. 



4-0 



AM 













































/^ 



















"\ W 2 0.^ 3 



\^ 9*^ T/ME / 



4 



V MINUTES 



50 















Table for fig. 4. 



Drift of zero obtained just after resetting the discharge- 

 surfaces. 



Time in Minutes. 



Zt;ro Position. 



In Fringes. 



In Mfi . 





 6 



15 

 19 

 30 

 39 

 49 







-o-i 



-01 

 -0-05 

 4- 0-05 

 4-0-15 

 4-0-25 





 -2-86 

 -2-86 

 -1-43 

 4-143 

 +4-29 

 +715 



The accompanying curve (fig. 4) shows a characteristic 

 variation of the zero, i. e„ the point at which the surfaces 

 break contact. This may be explained as follows : — 



The handling of the instrument in readjusting the discharge- 

 surfaces causes a rise of temperature. The subsequent fall of 

 temperature was shown by a shift of the zero in such a direction 

 as to open the gap. As the effect of handling gradually dis- 

 appeared, the instrument returned to its normal condition, 

 when the steadily rising curve indicated a rising temperature. 

 It often required six or eight hours of careful testing and 

 adjustment of room-temperatures to find the correct tempe- 

 rature at which the apparatus must be used. As an hour was 

 required to complete each observation, it was found advisable 

 to do most of the work at night, when the temperature could 

 most easily be kept constant during the long period required 

 for a complete series. 



