331 



galvanometers at the extremities of the wire should have acted simul- 

 taneously, as in the second experiment, and as would have been the 

 case had a short wire united the two extremities which proceeded 

 to the earth. 



Third Series. 



Exp. 6. One pole of the battery was connected with the earth, and 

 the opposite pole with one extremity of the 660 miles of wire, the 

 qther end remaining insulated; a delicate galvanometer was interposed 

 near the battery. Notwithstanding there was no circuit formed, the 

 needle showed a constant deflection of 33^; the feeble current 

 thus rendered evident is not so much to be attributed to imperfect 

 insulation, as to the uniform and continual dispersion of the static 

 electricity with which the wire is charged throughout its entire 

 length, in the same manner as would take place in any other 

 charged body placed in an insulating medium. The strength of 

 the current thus occasioned appears to be nearly, if not exactly, 

 proportional to the length of the wire added, as the following table 

 will show : the first column indicates the number of miles of wire 

 subjoined beyond the galvanometer, and the second the correspond- 

 ing deflections of the needle : 



miles. 







110 6 



220 12 



330 18 



440 23| 



550 28 



660 31 



Exp. 7. One end of the 660 miles of wire was now allowed to 

 remain constantly in contact with one of the poles of the battery ; 

 but the galvanometer was successively shifted to different distances 

 from the battery. The strength of the current was now shown to 

 be inversely as the distance of the galvanometer from the battery, 

 becoming null at its extremity, as shown in the following table. The 

 first column shows the distance from the battery at which the gal- 

 vanometer was placed, and the second column the corresponding 

 deflection of the needle. 



