MAGNETO-ELECTRIC INSTRUMENT. 



currents which are produced upon the conducting wire, while N 

 makes the half revolution N'" M' N ; and the arrows directed to 



Fig. 63. 

 M, 



\ 



M' 



left express the direction of the two currents produced, while sr 

 makes the half revolution N' M N". 



Thus it appears that in each revolution of the magnet, N o s, 

 four momentary currents are produced in the wire, two in one 

 direction during one semi-revolution, and two in the contrary 

 direction during the other semi-revolution. In the intervals 

 between these momentary currents there is a suspension of voltaic 

 action. 



164. It has been already shown how electric currents may be 

 instantaneously suspended, re-established, and reversed in their 

 direction by means of commutators (111). By such an expedient 

 properly adapted, it is easy to understand that by suspending the 

 currents in one of the two contrary directions, while the other is 

 allowed to pass, an intermitting current always running in the 

 same direction may be obtained. Or if the commutator be so 

 adapted that while the momentary currents in one direction are 

 allowed to run without interruption, those in the other direction 

 shall be reversed, we shall then have in each revolution four 

 momentary currents flowing in a common direction. The current 

 thus produced will be intermitting, that is, it will pass upon the., 

 wire by a succession of pulsations or intervals of transmission and 

 suspension, but since in each revolution of the magnet there are 

 two pulsations, that is, two intervals of transmission and two of 



B 2 3 



