NATURAL ELECTRIC CURRENTS. 97 



The terrestrial electric currents from east to 

 west about the earth are represented by the cur- 

 rent / n, and will cause the wire frame, while 

 transmitting a current, to turn in a conformable 

 direction east and west, and to manifest all the 

 characteristic properties of a compass needle, with 

 a north and south polarity. 



Considering the extended conducting wire/ , 

 in Fig. 19, to represent the direction of the terres- 

 trial currents from east to west, and the diago- 

 nally directed currents 2 3 4, 6 7 8, the directions 

 of currents approaching to and receding from the 

 horizontal terrestrial current, the short lateral 

 arrows would designate the resultant movements, 

 all at right angles to the linear direction of the 

 short wires, according to principles previously 

 explained. In Fig. 20, the vertical descent of the 

 current at E, toward / n, develops the resultant 

 movement denoted by the short lateral arrow No. 3 

 in Fig. 19, which tends to swing the end of the 

 frame E horizontally around ; while the ascent of 

 the current, at w, represents the relative direction 

 corresponding with No. 7 in Fig. 19. The result- 

 ant movement indicated by the short, dotted, lat- 

 eral arrows, Nos. 3-7, turn it to correspond in 

 direction with the current p n. 



To illustrate the identity of the reciprocal 

 action between electric currents circulating around 

 conducting wires, and the natural currents circu- 

 lating about loadstones, and all other magnetSi 



