put the transformer and the galvanometer in electrical con- 

 nection. 



The noise of the discharge of the cannon could just be 

 heard at L, and at every discharge the galvanometer would 

 throw before the noise of the discharge could reach the ear. 



The charge of powder and weight of bullet were the same 

 as in the first experiment. One side of the scale of the gal- 

 vanometer is marked by red figures and the other side by 

 black ones, so that it is convenient to indicate the direction of 

 the deflection by "red" and "black." 



A copper wire was stretched over the transformer, see Fig. 

 3, E, and the ends were connected to the poles of a crowfoot 

 cell, the wire from the copper pole being conducted over the 

 transformer in the same direction in which the bullet was fired. 

 AVhen the circuit was completed, the galvanometer deflected 

 to the black. If the current flows from the copper to the zinc, 

 then the induced current in the transformer would flow in the 

 opposite direction as indicated by the arrow H. 



If the galvanometer deflected to the black when the bullet 

 was fired, then it would be acting like a stream of negative 

 charges. If it deflected oppositely then it would indicate a 

 stream of positive charges. 



Under these conditions the following data were obtained, 

 on November 17, 1011. The firing commenced at 3 :30 P. M. 

 and closed at 4 :30 P. M. 



TABLE I. 



An examination of the table shows that the discharge of 

 the bullet caused the galvanometer to throw in a direction op- 

 posite to that caused by the closing of the circuit of the crow- 

 foot battery, which indicates that the current caused by the 

 bullet and the battery current are flowing in the same direc- 

 tion. Thus the bullet induced a current flowing in the same 

 direction in which it was moving. This result was decidedly 

 unexpected and an explanation will be offered later. 



It is to be noted that a wooden bullet gave a strong de- 

 flection. This shows that the deflection is not caused by eddy 

 currents due to the bullet, cutting the earth's field. The data 

 also indicate that we are not dealing with inertia effects. 



62 



