as Conductors of Electricity . 



299 



one another and with P ; this charged the condenser. Since 

 the quadrants were connected, the spot of light stood initially 

 at zero. The two pairs of quadrants were then disconnected 

 from each other, and discharge by the flame showed itself on 

 the electrometer-scale by a motion of the spot of light oat 

 over the scale from the zero. 



Each set of readings had of course to be concluded when 

 the light moved off the scale — that is, when the difference of 

 potential between the pairs of quadrants had increased to 

 about that of 4 Leclanches. 



The mean distance between the pieces of platinum-foil was 

 # 75 centim. ; the height of the flame was approximately 

 0*4 centim. Readings were made at intervals of 20 seconds, 

 time being given by the laboratory chronometer. 



There are given in detail in the tables (a), (b), (c), id) 

 below the results of observations, using batteries of 8 and 6 

 Leclanches respectively. The curves («), (/3), (7), (8) (Plate 

 VIII.) are obtained by plotting-out the numbers in the first two 

 columns of these tables, taking the observed scale-reading as 

 ordinate and time as abscissa ; the agreement with one another 

 of the observations is well shown by the smoothness of the 

 curves. In the tables the columns headed " calculated deflec- 

 tion " are obtained from the equations which were found, by 

 trial, to suit the curves best. The scale of readings is such 

 that 134 divisions = 2 volts, nearly. 



To find the constant for the apparatus, leakage was allowed 

 to go on for an hour without a flame. The potential fell from 

 715 scale-divisions to 637 in that time. 



+ quadrant insulated, 



(a) 



8 Leclanches^ 



715 divisions. 





Deflection. 





Deflection. 



Time. 





Time. 





Observed. 



Calculated. 



Observed. 



Calculated. 



m s 







m s 











697 



697 



4 



497-5 



496 



20 



678 





20 



484-5 





40 



659 





40 



470 





1 



640 



640 



5 



457 



455 



20 



622 





20 



444 





40 



604-5 





40 



431 





2 



588 



589 



6 



419 



418 



20 



571 





20 



407-5 





40 



555 





40 



395-5 





3 



540 



540 



7 



384 



384 



20 



525 "5 





20 



373 





40 



5105 





40 



362-5 











8 



352-5 



352-5 



X2 



