342 



Reciprocating Magnetic Attraction. 



and the gnlvanlc communication formed Ijy the amalgamated ends of 

 the wires dipping into cups of mercury. 



The whole will be more readily understood by a reference to the 

 annexed drawing ; A B is the horizontal magnet, about seven inches 

 lonz, and moveable on an axis at the center : its two extremities when 

 placed in a horizontal line, are about one inch from the north poles 

 of the upright magnets C and D. G and F are two large tumblers 

 containing diluted acid, in each of which is immersed a plate of zinc 

 surrounded with coppej:. I, m, s, t, are four brass thimbles soldered 

 to the zinc and popper of the batteries and filled with mercury. 



The galvanic magnet AB is wound with three strands of copper 

 bell wire, each about twenty five feet long ; the similar ends of these 

 are twisted together so as to form two stifi' wires, which project be- 

 yond the extremity B, and dip into the thimbles 5, t. 



To the wires q, r, two other wires are soldered so as to project in 

 an opposite direction, and dip into tlie thimbles I, in. The wires of 

 the galvanic magnet have thus, as it were, four projecting ends j and 

 by inspecting the figure it will be seen that the extremity m, wliiclf 

 dips into the cup attached to the copper of the battery in G corre- 

 sponds to the extremity ^ connecdng with the zinc F. 



When the batteries are in action, if the end B is depressed until 

 q, r dips into the cups s, t, AU instantly becomes a powerful mag- 

 net, liaving its north pole at B; this of course is repelled by the 

 north pole D, while at the same time it is attracted by C, the posi- 

 tion is consequendy changed, and o, p comes in contact with, the 

 mercury in I, m ; as soon as the communication is formed, the poles 

 are reversed, and the position again changed. If the tumblers be 



