48 BENJ. PIKE'S, JR., DESCRIPTIVE CATALOGUE. 



hammer attached to a silver spring, having a platina centre 

 on that part in contact with the point, and the end sup- 

 ported from one of the poles of the electro-magnet, the 

 hammer vibrating between the other poles and the platina 

 point. The point is supported from a milled -head screw, 

 having a milled-head nut to tighten it, and entering the top 

 of a brass frame, supported by two brass pillars. The screw 

 may be turned to vary the vibrations. 



The electro-magnet being charged by the battery current 

 attracts the hammer, or armature, but the current being 

 immediately interrupted thereby, in consequence of the 

 separation of the platina point from the spring, the arma- 

 ture flies back, and the contact being removed, is again at- 

 tracted and loosened, and thus a rapid vibration is carried 

 on, the shocks succeeding each other with such rapidity, as 

 to occasion only the sensation of numbness and powerful 

 contraction of the muscles. This instrument is packed in a 

 neat case with pot battery, pair of handles, pair of insulated 

 conductors, foot-plate, and the necessary wires, with a 

 quantity of blue vitriol wrapped in papers, each one contain- 

 ing the right quantity for charging the battery. 



Price, $14.00; or the instrument only, $10.00. 



Fig. 470. 



Magnetic Machine Vibrating from both Poles. (Fig. 470, 

 as above.) This instrument is the same as the preceding 

 one, but the armature vibrating from both poles of the mag- 

 net ; the spring being supported by a brass pillar fixed on 

 one of the brass bands that secure the helix to the board. 

 This instrument vibrates with great force, but the former 

 instrument is the least liable to derangement. The wires 



