356 



On the use of the Dynamic Multiplier. 



out the magnets, merely by the action of the coil. The pieces of 

 wood separating the mercury floods, or poles of the battery, should 

 be arranged in the direction of the radius of the coil, as that is the 

 position of equilibrium for the magnet. The opposite poles of a 

 magnet, conspiring with the action of the coil, make the revolution 

 extremely rapid. The interruption occurs twice in each revolution, 

 but it may be made more frequent if the number of partitions in the 

 cells be increased, and the magnetic poles in like manner. This 

 instrument is liable to one objection. The mercury is often dragged 

 across the partitions and the revolution ceases. This may in part 

 be obviated by pouring a little water upon its surface. 



Fig, 1, is a representation of a vibrating interruptor of my own in- 

 vention. A piece of soft iron wire one eighth of an inch in diameter, 

 and three inches long, is covered with copper wire, and made to vi- 

 brate rapidly between the poles of a horse shoe magnet. It should 

 be carefully suspended and well balanced. Its motion is increased if 

 the poles just touch the wires, to give the bar a spring. The cups 

 for mercury (p and n) are sections of glass tubes ; r is a thumb screw 

 for regulating the vibrations of the bar. If the four ends of the wires 

 be carefully adjusted near the surface of the mercury, by bringing 

 down the screw upon the bar, the vibrations may be rendered incon- 

 ceivably rapid. 



3 1 



