52 



BENJ. PIKE S, JR., DESCRIPTIVE CATALOGUE. 



brass pillars, over the middle of the spring (which screw can 

 be moved to the proper distance, to cause the vibrations to 

 continue with the best effect) ; the current from the battery 

 is carried through the helix, spring, and electro-magnet, by 

 connecting wires fastened in the brass cups, with binding 

 screws at the side of the machine. The fine wires are con- 

 nected with cups at the end of the machine, and in which 

 are secured wires connecting with handles, or other con- 

 ductors, for communicating the effect. 



Fig. 472. 



B.PIKEJ? 

 294- BROADWAY N.V. 



The galvanic battery consists of an oblong square vessel, 

 or box of copper, having a space all around of about an inch 

 inclosed with copper for the liquid, and within which is sus- 

 pended a square frame of zinc, so arranged as not to be in 

 contact with the copper, it being supported by a cross-bar 

 of metal, under which wood is fastened to insulate it from 

 the copper. There is a small tube in one of the corners of 

 the zinc, and also of the copper vessel, to insert the connect- 

 ing wires from the machine. There is a projecting piece 

 within each end of the inner apartment of the battery to set 

 the zinc on when not in use. The liquid employed is blue 

 vitriol (sulphate of copper), dissolved in hot water, about two 

 ounces to a quart of water, left to cool before using. The 

 liquid requires to be renewed when the acid is entirely taken 

 up by the zinc, which will be known by there being no de- 

 posit on the zinc, after being immersed for a few minutes ; 

 in which case the liquid is poured out, and a new solution 

 made, also any sediment cleaned out. The zinc frame 



