24 BENJ. PIKE S, JR., DESCRIPTIVE CATALOGUE. 



Fig. 443. 



Vibrating Magic Circle. (Fig. 443, as above.) This 

 instrument consists of an electro-magnet, mounted on a 

 mahogany base, and supported in a horizontal position by a 

 stout short pillar ; the wires or terminators of the electro- 

 magnet being soldered, beneath the base, to a cup with 

 binding screw on the base, and the end of a long brass 

 pillar, which pillar supports a plate at the top, and from 

 which is suspended, by a small spindle, a coil of wire in the 

 form of a magic circle, hanging in front of one of the poles 

 of the electro-magnet ; the ends of the coil dip into mercury 

 cups on the top of the plate. The circuit with the battery 

 is formed by. connecting one of the poles with the cup hav- 

 ing a binding screw, and the other with the pillar support- 

 ing the circle, causing the circle to be attracted over the 

 pole of the magnet, by which the wires in the mercury cup 

 are drawn out and the contact broken, the coil falling back ; 

 when the wires again dipping in the mercury, the contact is 

 renewed, and thus a constant vibrating of a circle over the 

 pole of the magnet takes place. Price, $6.00 



Electro- Magnet with Three Poles. (Fig. 444, next page.) 

 This consists of an iron rod, wound with insulated copper 

 wire ; the wire being wound in one direction through one 

 half of the rod, and then turning and being wound in the 

 contrary direction ; the extremities of the wires being con- 

 nected with cups having binding screws on the base of the 



