
DISRUPTIVE DISCHARGE OF ELECTRICITY. 687 
readings indicate a straight line so exactly, that we may safely infer that the 
deflections of the image from zero are strictly proportional to the charge on 
the inducing balls. 
We had arranged to complete the calibration of the electrometer on Thurs- 
day forenoon (27th June); but as the deflection on the scale, when the dividing 
ball was brought into contact, always fell rapidly in the negative direction, and 
went to a great distance beyond the proper zero, it was impossible to proceed. 
The indications were the same as when negative electricity is escaping into the 
surrounding air; and that such was the case then was evidenced by the severe 
thunderstorm which came on soon after. 
Our thanks are due to Professor Tarr, in whose laboratory these experi- 
ments were made, for many valuable suggestions. 
VOL. XXVIII. PART Ii. : 8Q 
