OP ARTS AND SCIENCES. 131 



limit of the scale (25 scale divisions), and until stopped by the side 

 of the case of the instrument. The deflection indicated a very high 

 positive potential for the air in the vicinity of the kite. To decrease 

 the sensibility of the instrument, the battery charging the needle was 

 reduced from 100 cells to 10 cells, and finally to a single cell. The 

 Beetz battery of 100 cells has a difference of potential between its 

 plus and minus poles of about 100 volts. The needle-pointer being 

 at 0, the plus pole of the battery being connected to one set of quad- 

 rants, caused a deflection of 5.5 scale divisions. Connecting the insu- 

 lated kite-string to the same terminal, the aluminium pointer was 

 deflected with force to the side of the case. The least value of the 

 difference between the kite potential and tlie ground was about 

 500 volts. The wind at tliis time was blowing freshly from the 

 northwest, and the kite was seemingly stationary. Touching the 

 ground wire, for a second, to the kite wire, a small spark about 

 one twentieth of an inch in length was obtained. This, of course, 

 discharged the wire, and the pointer returned to 0, returning, how- 

 ever, almost at once, again to the side of the case. In the hope of 

 getting the deflection within the limits of the scale of the instrument, 

 the quadrants connected with the ground were instead connected 

 with the plus pole of the 100-cell Beetz battery. The deflection 

 under this arrangement would represent the excess value of the air 

 potential over that of the battery terminal. The deflection, however, 

 still remained off the scale, though evidently not very distant. This 

 deflection was maintained all the forenoon. The sky was covered 

 with a low pallium of dark stratus clouds, and the weather was gener- 

 ally muggy and threatening. At three p. m. the kite was sent up as 

 before. The same character of deflection prevailed, and the sparks 

 obtained on connecting the ground with the kite wire were larger 

 and as frequent as in the morning. The shock felt on touching these 

 two wires with the fingers slightly moistened was about the same as 

 one gets from a small -sized Leyden jar. The weather had cleared up, 

 and it was now a clear and pleasant June afternoon. The wind was 

 less steady than in the morning, coming more in pufTs. In conse- 

 quence of this, the kite was less steady, and kept rising and falling. 

 Every time, without exception, when tiie kite would ri-^e, the needle 

 indicated an increase in the potential ; and, on tlie other hand, as 

 regularly as the kite fell the deflection decreased. Wlieii the kite 

 would get apparently within 100 feet of the ground, tlie deflection 

 would often fill to 8, 10, and sometimes less, of the scale divisions. 

 Tlie movements of the kite were told frt)m watching the movements 



