230 On a new Action of the Magnet on Electric Currents. 



except an induction-current at the moment of making or break- 

 ing the magnet circuit. 



It has been stated above that in the experiments thus far 

 tried the current apparently tends to move, without actually 

 moving, toward the side of the conductor. I have in mind a 

 form of apparatus which will, I think, allow the current to 

 follow this tendency, and move across the lines of magnetic 

 force. If this experiment succeeds,/>ne or two others imme- 

 diately suggest themselves. 



To make a more complete and accurate study of the phe- 

 nomenon described in the preceding pages, availing myself 

 of the advice and assistance of Prof. Rowland, will probably 

 occupy me for some months to come. 



Baltimore, Nov. 19th, 1879. 



It is perhaps allowable to speak of the action of the magnet 

 as setting up in the strip of gold-leaf a new electromotive 

 force at right angles to the primary electromotive force. 



This new electromotive force cannot under ordinary con- 

 ditions manifest itself, the circuit in which it might work 

 being incomplete. When the circuit is completed by means 

 of the Thomson galvanometer, a current flows. 



The actual current through this galvanometer depends of 

 course upon the resistance of the galvanometer and its con- 

 nexions, as well as upon the distance between the two points 

 of the gold-leaf at which the ends of the wires from the gal- 

 vanometer are applied. We cannot, therefore, take the ratio 

 of C and c above as the ratio of the primary and the trans- 

 verse electromotive forces just mentioned. 



If we represent by E' the difference of potential of two 

 points a centimetre apart on the transverse diameter of the 

 strip of gold-leaf, and by E the difference of potential of two 

 points a centimetre apart on the longitudinal diameter of the 

 same, a rough and hasty calculation for the experiments 



E 



already made shows the ratio ^ to have varied from about 



3000 to about 6500. 



The transverse electromotive force E r seems to be, under 

 ordinary circumstances, proportional to Mv, where M is the 

 intensity of the magnetic field and v is the velocity of the 

 electricity in the gold-leaf. Writing for v the equivalent ex- 

 pression — , where C is the primary current through a strip of 

 s 



the gold-leaf 1 centim. wide, and s the area of section of the 



i, w MC 

 same, we nave E' oc . 



November 22nd, 1879. 



